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Sample records for cell surface interaction

  1. Multi-scale cell/surface interaction on modified titanium aluminum vanadium surfaces

    Science.gov (United States)

    Chen, Jianbo

    This dissertation presents a series of experimental studies of the effects of multi-scale cell/surface interactions on modified Ti-6Al-4V surfaces. These include laser-grooved surfaces; porous structures and RGD-coated laser-grooved surfaces. A nano-second DPSS UV lasers with a Gaussian pulse energy profile was used to introduce the desired micro-groove geometries onto Ti-6Al-4V surfaces. This was done without inducing micro-cracks or significant changes in surface chemistry within the heat affected zones. The desired 8-12 mum groove depths and widths were achieved by the control of pulse frequency, scan speed, and the lens focal length that controls spot size. The interactions between human osteosarcoma (HOS) cells and laser-grooved Ti-6Al-4V surfaces were investigated after 48 hours of cell culture. The cell behavior, including cell spreading, alignment and adhesion, was elucidated using scanning electronic microscopy (SEM), immuno-fluorescence staining and enzymatic detachment. Contact guidance was shown to increase as grooved spacing decreased. For the range of micro-groove geometries studied, micro-grooves with groove spacings of 20 mum provided the best combination of cell orientation and adhesion. Short-term adhesion experiments (15 mins to 1 day) also revealed that there is a positive correlation between cell orientation and cell adhesion. Contact guidance on the micro-grooved surfaces is shown to be enhanced by nano- and micro-scale asperities that provide sites for the attachment of lamellopodia during cell locomotion and spreading. Contact guidance is also promoted by the geometrical confinement provided by laser grooves. An experimental study of initial cell spreading and ingrowth into Ti-6Al-4V porous structures was also carried out on porous structures with different pore sizes and geometries. A combination of SEM, the tetrazolium salt (MTT) colorimetric assay and enzymatic detachment were used to study cell spreading and adhesion. The extent of cell

  2. Microarrays for the evaluation of cell-biomaterial surface interactions

    Science.gov (United States)

    Thissen, H.; Johnson, G.; McFarland, G.; Verbiest, B. C. H.; Gengenbach, T.; Voelcker, N. H.

    2007-01-01

    The evaluation of cell-material surface interactions is important for the design of novel biomaterials which are used in a variety of biomedical applications. While traditional in vitro test methods have routinely used samples of relatively large size, microarrays representing different biomaterials offer many advantages, including high throughput and reduced sample handling. Here, we describe the simultaneous cell-based testing of matrices of polymeric biomaterials, arrayed on glass slides with a low cell-attachment background coating. Arrays were constructed using a microarray robot at 6 fold redundancy with solid pins having a diameter of 375 μm. Printed solutions contained at least one monomer, an initiator and a bifunctional crosslinker. After subsequent UV polymerisation, the arrays were washed and characterised by X-ray photoelectron spectroscopy. Cell culture experiments were carried out over 24 hours using HeLa cells. After labelling with CellTracker ® Green for the final hour of incubation and subsequent fixation, the arrays were scanned. In addition, individual spots were also viewed by fluorescence microscopy. The evaluation of cell-surface interactions in high-throughput assays as demonstrated here is a key enabling technology for the effective development of future biomaterials.

  3. Bacteria-surface interactions.

    Science.gov (United States)

    Tuson, Hannah H; Weibel, Douglas B

    2013-05-14

    The interaction of bacteria with surfaces has important implications in a range of areas, including bioenergy, biofouling, biofilm formation, and the infection of plants and animals. Many of the interactions of bacteria with surfaces produce changes in the expression of genes that influence cell morphology and behavior, including genes essential for motility and surface attachment. Despite the attention that these phenotypes have garnered, the bacterial systems used for sensing and responding to surfaces are still not well understood. An understanding of these mechanisms will guide the development of new classes of materials that inhibit and promote cell growth, and complement studies of the physiology of bacteria in contact with surfaces. Recent studies from a range of fields in science and engineering are poised to guide future investigations in this area. This review summarizes recent studies on bacteria-surface interactions, discusses mechanisms of surface sensing and consequences of cell attachment, provides an overview of surfaces that have been used in bacterial studies, and highlights unanswered questions in this field.

  4. Surface modification of hydrophobic polymers for improvement of endothelial cell-surface interactions

    NARCIS (Netherlands)

    Dekker, A.; Dekker, A.; Reitsma, K.; Beugeling, T.; Beugeling, T.; Bantjes, A.; Bantjes, A.; Feijen, Jan; Kirkpatrick, C.J.; van Aken, W.G.

    1992-01-01

    The aim of this study is to improve the interaction of endothelial cells with polymers used in vascular prostheses. Polytetrafluoroethylene (PTFE; Teflon) films were treated by means of nitrogen and oxygen plasmas. Depending on the plasma exposure time, modified PTFE surfaces showed water-contact

  5. Remote Control of Tissue Interactions via Engineered Photo-switchable Cell Surfaces

    Science.gov (United States)

    Luo, Wei; Pulsipher, Abigail; Dutta, Debjit; Lamb, Brian M.; Yousaf, Muhammad N.

    2014-09-01

    We report a general cell surface molecular engineering strategy via liposome fusion delivery to create a dual photo-active and bio-orthogonal cell surface for remote controlled spatial and temporal manipulation of microtissue assembly and disassembly. Cell surface tailoring of chemoselective functional groups was achieved by a liposome fusion delivery method and quantified by flow cytometry and characterized by a new cell surface lipid pull down mass spectrometry strategy. Dynamic co-culture spheroid tissue assembly in solution and co-culture tissue multilayer assembly on materials was demonstrated by an intercellular photo-oxime ligation that could be remotely cleaved and disassembled on demand. Spatial and temporal control of microtissue structures containing multiple cell types was demonstrated by the generation of patterned multilayers for controlling stem cell differentiation. Remote control of cell interactions via cell surface engineering that allows for real-time manipulation of tissue dynamics may provide tools with the scope to answer fundamental questions of cell communication and initiate new biotechnologies ranging from imaging probes to drug delivery vehicles to regenerative medicine, inexpensive bioreactor technology and tissue engineering therapies.

  6. Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces.

    Science.gov (United States)

    Ziebart, Thomas; Schnell, Anne; Walter, Christian; Kämmerer, Peer W; Pabst, Andreas; Lehmann, Karl M; Ziebart, Johanna; Klein, Marc O; Al-Nawas, Bilal

    2013-01-01

    Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces. EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction. Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces. The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities. In

  7. Interaction of KSHV with Host Cell Surface Receptors and Cell Entry

    Directory of Open Access Journals (Sweden)

    Mohanan Valiya Veettil

    2014-10-01

    Full Text Available Virus entry is a complex process characterized by a sequence of events. Since the discovery of KSHV in 1994, tremendous progress has been made in our understanding of KSHV entry into its in vitro target cells. KSHV entry is a complex multistep process involving viral envelope glycoproteins and several cell surface molecules that is utilized by KSHV for its attachment and entry. KSHV has a broad cell tropism and the attachment and receptor engagement on target cells have an important role in determining the cell type-specific mode of entry. KSHV utilizes heparan sulfate, integrins and EphrinA2 molecules as receptors which results in the activation of host cell pre-existing signal pathways that facilitate the subsequent cascade of events resulting in the rapid entry of virus particles, trafficking towards the nucleus followed by viral and host gene expression. KSHV enters human fibroblast cells by dynamin dependant clathrin mediated endocytosis and by dynamin independent macropinocytosis in dermal endothelial cells. Once internalized into endosomes, fusion of the viral envelope with the endosomal membranes in an acidification dependent manner results in the release of capsids which subsequently reaches the nuclear pore vicinity leading to the delivery of viral DNA into the nucleus. In this review, we discuss the principal mechanisms that enable KSHV to interact with the host cell surface receptors as well as the mechanisms that are required to modulate cell signaling machinery for a successful entry.

  8. Surface modified superparamagnetic nanoparticles: Interaction with fibroblasts in primary cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Chapa Gonzalez, Christian; Roacho Pérez, Jorge A.; Martínez Pérez, Carlos A.; Olivas Armendáriz, Imelda [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro #610 norte, Col. Partido Romero, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico); Jimenez Vega, Florinda [Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Anillo envolvente del PRONAF y Estocolmo, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico); Castrejon Parga, Karen Y. [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro #610 norte, Col. Partido Romero, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico); Garcia Casillas, Perla E., E-mail: pegarcia@uacj.mx [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro #610 norte, Col. Partido Romero, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico)

    2014-12-05

    Highlights: • An inorganic layer before an organic material shell onto MNPs improves cell viability. • The coating type and the concentration of nanoparticles directly affect cell viability. • Modified magnetite nanoparticles with organic and inorganic materials was developed. - Abstract: The development of a variety of medical applications such as drug delivery, cell labeling, and medical imaging have been possible owing to the unique features exhibited by magnetic nanoparticles. Nanoparticle–cell interaction is related to the surface aspects of nanoparticle, which may be described based on their chemistry or inorganic/organic characteristics. The coating on particle surface reduces the inter-particle interactions and provides properties such as biocompatibility. Among the coating materials used for nanoparticles employed in biomedical applications, oleic acid is one of the most utilized due to its biocompatibility. However, a major drawback with this naturally occurring fatty acid is that it is easily oxidized by cells and this reduces their performance in biomedical applications. In order to avoid the direct contact of the cell with the magnetite particle, coating with an inorganic material prior to the oleic acid shell would be effective. This would retard the magnetite dissociation thereby improve the cell viability. Here we report our investigation on the effect of surface modified magnetite nanoparticles (MNPs) on the cell viability using primary cultures incubated with those particles. We prepared magnetite nanoparticles by chemical co-precipitation method; nanoparticle surface was first modified by silanol condensation followed by chemisorption of oleic acid. All nanostructures have a particle size less than 100 nm, depending on the material coating and superparamagnetic behavior. The saturated magnetizations (M{sub s}) of the magnetite samples coated with oleic acid (MAO; 49.15 emu/g) and double shell silica-oleic acid (MSAO; 46.16 emu/g) are

  9. Fibronectin-cell interactions

    DEFF Research Database (Denmark)

    Couchman, J R; Austria, M R; Woods, A

    1990-01-01

    Fibronectins are widespread extracellular matrix and body fluid glycoproteins, capable of multiple interactions with cell surfaces and other matrix components. Their structure at a molecular level has been resolved, yet there are still many unanswered questions regarding their biologic activity...... in vivo. Much data suggests that fibronectins may promote extracellular matrix assembly, and cell adhesion to those matrices. However, one outstanding enigma is that fibronectins may, under different circumstances, promote both cell migration and anchorage. An analysis of the interaction of fibroblasts...... with proteolytically derived and purified domains of plasma fibronectin revealed that the type of adhesion and the correlated cytoskeletal organization depended on multiple interactions of fibronectin domains with the cell surface. Human dermal fibroblasts were capable of interacting with the integrin-binding domain...

  10. The Non-Specific Binding of Fluorescent-Labeled MiRNAs on Cell Surface by Hydrophobic Interaction.

    Science.gov (United States)

    Lu, Ting; Lin, Zongwei; Ren, Jianwei; Yao, Peng; Wang, Xiaowei; Wang, Zhe; Zhang, Qunye

    2016-01-01

    MicroRNAs are small noncoding RNAs about 22 nt long that play key roles in almost all biological processes and diseases. The fluorescent labeling and lipofection are two common methods for changing the levels and locating the position of cellular miRNAs. Despite many studies about the mechanism of DNA/RNA lipofection, little is known about the characteristics, mechanisms and specificity of lipofection of fluorescent-labeled miRNAs. Therefore, miRNAs labeled with different fluorescent dyes were transfected into adherent and suspension cells using lipofection reagent. Then, the non-specific binding and its mechanism were investigated by flow cytometer and laser confocal microscopy. The results showed that miRNAs labeled with Cy5 (cyanine fluorescent dye) could firmly bind to the surface of adherent cells (Hela) and suspended cells (K562) even without lipofection reagent. The binding of miRNAs labeled with FAM (carboxyl fluorescein) to K562 cells was obvious, but it was not significant in Hela cells. After lipofectamine reagent was added, most of the fluorescently labeled miRNAs binding to the surface of Hela cells were transfected into intra-cell because of the high transfection efficiency, however, most of them were still binding to the surface of K562 cells. Moreover, the high-salt buffer which could destroy the electrostatic interactions did not affect the above-mentioned non-specific binding, but the organic solvent which could destroy the hydrophobic interactions eliminated it. These results implied that the fluorescent-labeled miRNAs could non-specifically bind to the cell surface by hydrophobic interaction. It would lead to significant errors in the estimation of transfection efficiency only according to the cellular fluorescence intensity. Therefore, other methods to evaluate the transfection efficiency and more appropriate fluorescent dyes should be used according to the cell types for the accuracy of results.

  11. The Non-Specific Binding of Fluorescent-Labeled MiRNAs on Cell Surface by Hydrophobic Interaction.

    Directory of Open Access Journals (Sweden)

    Ting Lu

    Full Text Available MicroRNAs are small noncoding RNAs about 22 nt long that play key roles in almost all biological processes and diseases. The fluorescent labeling and lipofection are two common methods for changing the levels and locating the position of cellular miRNAs. Despite many studies about the mechanism of DNA/RNA lipofection, little is known about the characteristics, mechanisms and specificity of lipofection of fluorescent-labeled miRNAs.Therefore, miRNAs labeled with different fluorescent dyes were transfected into adherent and suspension cells using lipofection reagent. Then, the non-specific binding and its mechanism were investigated by flow cytometer and laser confocal microscopy. The results showed that miRNAs labeled with Cy5 (cyanine fluorescent dye could firmly bind to the surface of adherent cells (Hela and suspended cells (K562 even without lipofection reagent. The binding of miRNAs labeled with FAM (carboxyl fluorescein to K562 cells was obvious, but it was not significant in Hela cells. After lipofectamine reagent was added, most of the fluorescently labeled miRNAs binding to the surface of Hela cells were transfected into intra-cell because of the high transfection efficiency, however, most of them were still binding to the surface of K562 cells. Moreover, the high-salt buffer which could destroy the electrostatic interactions did not affect the above-mentioned non-specific binding, but the organic solvent which could destroy the hydrophobic interactions eliminated it.These results implied that the fluorescent-labeled miRNAs could non-specifically bind to the cell surface by hydrophobic interaction. It would lead to significant errors in the estimation of transfection efficiency only according to the cellular fluorescence intensity. Therefore, other methods to evaluate the transfection efficiency and more appropriate fluorescent dyes should be used according to the cell types for the accuracy of results.

  12. Interaction between tumor cell surface receptor RAGE and proteinase 3 mediates prostate cancer metastasis to bone

    Science.gov (United States)

    Kolonin, Mikhail G.; Sergeeva, Anna; Staquicini, Daniela I.; Smith, Tracey L.; Tarleton, Christy A.; Molldrem, Jeffrey J.; Sidman, Richard L.; Marchiò, Serena; Pasqualini, Renata; Arap, Wadih

    2017-01-01

    Human prostate cancer often metastasizes to bone, but the biological basis for such site-specific tropism remains largely unresolved. Recent work led us to hypothesize that this tropism may reflect pathogenic interactions between RAGE, a cell surface receptor expressed on malignant cells in advanced prostate cancer, and proteinase 3 (PR3), a serine protease present in inflammatory neutrophils and hematopoietic cells within the bone marrow microenvironment. In this study, we establish that RAGE-PR3 interaction mediates homing of prostate cancer cells to the bone marrow. PR3 bound to RAGE on the surface of prostate cancer cells in vitro, inducing tumor cell motility through a non-proteolytic signal transduction cascade involving activation and phosphorylation of ERK1/2 and JNK1. In preclinical models of experimental metastasis, ectopic expression of RAGE on human prostate cancer cells was sufficient to promote bone marrow homing within a short time frame. Our findings demonstrate how RAGE-PR3 interactions between human prostate cancer cells and the bone marrow microenvironment mediate bone metastasis during prostate cancer progression, with potential implications for prognosis and therapeutic intervention. PMID:28428279

  13. Nano Petri dishes: a new polystyrene platform for studying cell-nanoengineered surface interactions

    Science.gov (United States)

    Cha, Kyoung Je; Na, Moon-Hee; Kim, Hyung Woo; Kim, Dong Sung

    2014-05-01

    In this study, we fabricated and fully characterized a new type of polystyrene (PS) cell-culture platform containing nanoengineered surfaces (NES), referred to as a nano Petri dish, which can be used at the transition stage of basic cell-NES interaction studies for clinical applications. Nano-injection molding in this study was used for the mass production of the nano Petri dish having nanopore arrays. The effects of processing parameters of the injection molding on the replication quality of the nanopore arrays were quantitatively evaluated by means of design of experiments based on the Taguchi method. This allowed efficient and reliable cell culture studies by providing large numbers of the same dishes, in addition to removing the fixation step of the NES plates inside the cell-culture container. Physical, chemical and mechanical properties of the NES, as well as cell behavior including attachment and proliferation of human osteosarcoma MG-63 cells on the NES, were then characterized, with and without the oxygen plasma surface treatment.

  14. Real-time and label-free analysis of binding thermodynamics of carbohydrate-protein interactions on unfixed cancer cell surfaces using a QCM biosensor

    Science.gov (United States)

    Li, Xueming; Song, Siyu; Shuai, Qi; Pei, Yihan; Aastrup, Teodor; Pei, Yuxin; Pei, Zhichao

    2015-01-01

    A novel approach to the study of binding thermodynamics and kinetics of carbohydrate-protein interactions on unfixed cancer cell surfaces using a quartz crystal microbalance (QCM) biosensor was developed, in which binding events take place at the cell surface, more closely mimicking a biologically relevant environment. In this study, colon adenocarcinoma cells (KM-12) and ovary adenocarcinoma cells (SKOV-3) grew on the optimized polystyrene-coated biosensor chip without fixation. The association and dissociation between the cell surface carbohydrates and a range of lectins, including WGA, Con A, UEA-I, GS-II, PNA and SBA, were monitored in real time and without label for evaluation of cell surface glycosylation. Furthermore, the thermodynamic and kinetic parameters of the interaction between lectins and cell surface glycan were studied, providing detailed information about the interactions, such as the association rate constant, dissociation rate constant, affinity constant, as well as the changes of entropy, enthalpy and Gibbs free energy. This application provides an insight into the cell surface glycosylation and the complex molecular recognition on the intact cell surface, which may have impacts on disease diagnosis and drug discovery. PMID:26369583

  15. Nano Petri dishes: a new polystyrene platform for studying cell-nanoengineered surface interactions

    International Nuclear Information System (INIS)

    Cha, Kyoung Je; Na, Moon-Hee; Kim, Hyung Woo; Kim, Dong Sung

    2014-01-01

    In this study, we fabricated and fully characterized a new type of polystyrene (PS) cell-culture platform containing nanoengineered surfaces (NES), referred to as a nano Petri dish, which can be used at the transition stage of basic cell–NES interaction studies for clinical applications. Nano-injection molding in this study was used for the mass production of the nano Petri dish having nanopore arrays. The effects of processing parameters of the injection molding on the replication quality of the nanopore arrays were quantitatively evaluated by means of design of experiments based on the Taguchi method. This allowed efficient and reliable cell culture studies by providing large numbers of the same dishes, in addition to removing the fixation step of the NES plates inside the cell-culture container. Physical, chemical and mechanical properties of the NES, as well as cell behavior including attachment and proliferation of human osteosarcoma MG-63 cells on the NES, were then characterized, with and without the oxygen plasma surface treatment. (paper)

  16. Fibrillar Structure and Charge Determine the Interaction of Polyglutamine Protein Aggregates with the Cell Surface*

    Science.gov (United States)

    Trevino, R. Sean; Lauckner, Jane E.; Sourigues, Yannick; Pearce, Margaret M.; Bousset, Luc; Melki, Ronald; Kopito, Ron R.

    2012-01-01

    The pathogenesis of most neurodegenerative diseases, including transmissible diseases like prion encephalopathy, inherited disorders like Huntington disease, and sporadic diseases like Alzheimer and Parkinson diseases, is intimately linked to the formation of fibrillar protein aggregates. It is becoming increasingly appreciated that prion-like intercellular transmission of protein aggregates can contribute to the stereotypical spread of disease pathology within the brain, but the mechanisms underlying the binding and uptake of protein aggregates by mammalian cells are largely uninvestigated. We have investigated the properties of polyglutamine (polyQ) aggregates that endow them with the ability to bind to mammalian cells in culture and the properties of the cell surface that facilitate such uptake. Binding and internalization of polyQ aggregates are common features of mammalian cells and depend upon both trypsin-sensitive and trypsin-resistant saturable sites on the cell surface, suggesting the involvement of cell surface proteins in this process. polyQ aggregate binding depends upon the presence of a fibrillar amyloid-like structure and does not depend upon electrostatic interaction of fibrils with the cell surface. Sequences in the huntingtin protein that flank the amyloid-forming polyQ tract also influence the extent to which aggregates are able to bind to cell surfaces. PMID:22753412

  17. The interaction between LYVE-1 with hyaluronan on the cell surface may play a role in the diversity of adhesion to cancer cells.

    Science.gov (United States)

    Du, Yan; Liu, Hua; He, Yiqing; Liu, Yiwen; Yang, Cuixia; Zhou, Muqing; Wang, Wenjuan; Cui, Lian; Hu, Jiajie; Gao, Feng

    2013-01-01

    Hyaluronan (HA), a simple disaccharide unit, can polymerize and is considered a primary component of the extracellular matrix, which has a wide range of biological functions. In recent years, HA was found on the surface of tumor cells. According to previous reports, differing HA content on the cell surface of tumor cells is closely related to lymph node metastases, but the mechanisms mediating this process remained unclear. This research intended to study the surface content of HA on tumor cells and analyze cell adhesive changes caused by the interaction between HA and its lymphatic endothelial receptor (LYVE-1). We screened and observed high HA content on HS-578T breast cells and low HA content on MCF-7 breast cells through particle exclusion, immunofluorescence and flow cytometry experiments. The expression of LYVE-1, the lymph-vessel specific HA receptor, was consistent with our previous report and enhanced the adhesion of HA(high)-HS-578T cells to COS-7(LYVE-1(+)) through HA in cell static adhesion and dynamic parallel plate flow chamber experiments. MCF-7 breast cells contain little HA on the surface; however, our results showed little adhesion difference between MCF-7 cells and COS-7(LYVE-1(+)) and COS-7(LYVE-1(-)) cells. Similar results were observed concerning the adhesion of HS-578T cells or MCF-7 cells to SVEC4-10 cells. Furthermore, we observed for the first time that the cell surface HA content of high transfer tumor cells was rich, and we visualized the cross-linking of HA cable structures, which may activate LYVE-1 on lymphatic endothelial cells, promoting tumor adhesion. In summary, high-low cell surface HA content of tumor cells through the interaction with LYVE-1 leads to adhesion differences.

  18. Surface modification for interaction study with bacteria and preosteoblast cells

    Science.gov (United States)

    Song, Qing

    Surface modification plays a pivotal role in bioengineering. Polymer coatings can provide biocompatibility and biofunctionalities to biomaterials through surface modification. In this dissertation, initiated chemical vapor deposition (iCVD) was utilized to coat two-dimensional (2D) and three-dimensional (3D) substrates with differently charged polyelectrolytes in order to generate antimicrobial and osteocompatible biomaterials. ICVD is a modified CVD technique that enables surface modification in an all-dry condition without substrate damage and solvent contamination. The free-radical polymerization allows the vinyl polymers to conformally coat on various micro- and nano-structured substrates and maintains the delicate structure of the functional groups. The vapor deposition of polycations provided antimicrobial activity to planar and porous substrates through destroying the negatively charged bacterial membrane and brought about high contact-killing efficiency (99.99%) against Gram-positive Bacillus subtilis and Gram-negative Escherichia coli. Additionally, the polyampholytes synthesized by iCVD exhibited excellent antifouling performance against the adhesion of Gram-positive Listeria innocua and Gram-negative E. coli in phosphate buffered saline (PBS). Their antifouling activities were attributed to the electrostatic interaction and hydration layers that served as physical and energetic barriers to prevent bacterial adhesion. The contact-killing and antifouling polymers synthesized by iCVD can be applied to surface modification of food processing equipment and medical devices with the aim of reducing foodborne diseases and medical infections. Moreover, the charged polyelectrolyte modified 2D polystyrene surfaces displayed good osteocompatibility and enhanced osteogenesis of preosteoblast cells than the un-modified polystyrene surface. In order to promote osteoinduction of hydroxyapatite (HA) scaffolds, bioinspired polymer-controlled mineralization was conducted

  19. Dynamic Morphological Changes Induced By GM1 and Protein Interactions on the Surface of Cell-Sized Liposomes

    Directory of Open Access Journals (Sweden)

    Masahiro Takagi

    2013-06-01

    Full Text Available It is important to understand the physicochemical mechanisms that are responsible for the morphological changes in the cell membrane in the presence of various stimuli such as osmotic pressure. Lipid rafts are believed to play a crucial role in various cellular processes. It is well established that Ctb (Cholera toxin B subunit recognizes and binds to GM1 (monosialotetrahexosylganglioside on the cell surface with high specificity and affinity. Taking advantage of Ctb-GM1 interaction, we examined how Ctb and GM1 molecules affect the dynamic movement of liposomes. GM1 a natural ligand for cholera toxin, was incorporated into liposome and the interaction between fluorescent Ctb and the liposome was analyzed. The interaction plays an important role in determining the various surface interaction phenomena. Incorporation of GM1 into membrane leads to an increase of the line tension leading to either rupture of liposome membrane or change in the morphology of the membrane. This change in morphology was found to be GM1 concentration specific. The interaction between Ctb-GM1 leads to fast and easy rupture or to morphological changes of the liposome. The interactions of Ctb and the glycosyl chain are believed to affect the surface and the curvature of the membrane. Thus, the results are highly beneficial in the study of signal transduction processes.

  20. Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

    Science.gov (United States)

    Kulkarni, Sayali; Misra, Chitra Seetharam; Gupta, Alka; Ballal, Anand

    2016-01-01

    ABSTRACT Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6- to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. IMPORTANCE The present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous

  1. Oxygen Modulates Human Decidual Natural Killer Cell Surface Receptor Expression and Interactions with Trophoblasts1

    Science.gov (United States)

    Wallace, Alison E.; Goulwara, Sonu S.; Whitley, Guy S.; Cartwright, Judith E.

    2014-01-01

    Decidual natural killer (dNK) cells have been shown to both promote and inhibit trophoblast behavior important for decidual remodeling in pregnancy and have a distinct phenotype compared to peripheral blood NK cells. We investigated whether different levels of oxygen tension, mimicking the physiological conditions of the decidua in early pregnancy, altered cell surface receptor expression and activity of dNK cells and their interactions with trophoblast. dNK cells were isolated from terminated first-trimester pregnancies and cultured in oxygen tensions of 3%, 10%, and 21% for 24 h. Cell surface receptor expression was examined by flow cytometry, and the effects of secreted factors in conditioned medium (CM) on the trophoblast cell line SGHPL-4 were assessed in vitro. SGHPL-4 cells treated with dNK cell CM incubated in oxygen tensions of 10% were significantly more invasive (P cells treated with dNK cell CM incubated in oxygen tensions of 3% or 21%. After 24 h, a lower percentage of dNK cells expressed CD56 at 21% oxygen (P cells expressed NKG2D at 10% oxygen (P oxygen tensions, with large patient variation. This study demonstrates dNK cell phenotype and secreted factors are modulated by oxygen tension, which induces changes in trophoblast invasion and endovascular-like differentiation. Alterations in dNK cell surface receptor expression and secreted factors at different oxygen tensions may represent regulation of function within the decidua during the first trimester of pregnancy. PMID:25232021

  2. Regulatory CD4 T cells inhibit HIV-1 expression of other CD4 T cell subsets via interactions with cell surface regulatory proteins.

    Science.gov (United States)

    Zhang, Mingce; Robinson, Tanya O; Duverger, Alexandra; Kutsch, Olaf; Heath, Sonya L; Cron, Randy Q

    2018-03-01

    During chronic HIV-1 infection, regulatory CD4 T cells (Tregs) frequently represent the largest subpopulation of CD4 T cell subsets, implying relative resistant to HIV-1. When HIV-1 infection of CD4 T cells was explored in vitro and ex vivo from patient samples, Tregs possessed lower levels of HIV-1 DNA and RNA in comparison with conventional effector and memory CD4 T cells. Moreover, Tregs suppressed HIV-1 expression in other CD4 T cells in an in vitro co-culture system. This suppression was mediated in part via multiple inhibitory surface proteins expressed on Tregs. Antibody blockade of CTLA-4, PD-1, and GARP on Tregs resulted in increased HIV-1 DNA integration and mRNA expression in neighboring CD4 T cells. Moreover, antibody blockade of Tregs inhibitory proteins resulted in increased HIV-1 LTR transcription in co-cultured CD4 T cells. Thus, Tregs inhibit HIV-1 infection of other CD4 T cell subsets via interactions with inhibitory cell surface proteins. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Interaction of progenitor bone cells with different surface modifications of titanium implant

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wen-Cheng, E-mail: wencchen@fcu.edu.tw [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Chen, Ya-Shun [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Ko, Chia-Ling [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Dental Medical Devices and Materials Research Center, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Lin, Yi; Kuo, Tzu-Huang; Kuo, Hsien-Nan [Medical Device Development Division, Metal Industries Research and Development Centre, Kaohsiung 82151, Taiwan (China)

    2014-04-01

    Changes in the physical and chemical properties of Ti surfaces can be attributed to cell performance, which improves surface biocompatibility. The cell proliferation, mineralization ability, and gene expression of progenitor bone cells (D1 cell) were compared on five different Ti surfaces, namely, mechanical grinding (M), electrochemical modification through potentiostatic anodization (ECH), sandblasting and acid etching (SLA), sandblasting, hydrogen peroxide treatment, and heating (SAOH), and sandblasting, alkali heating, and etching (SMART). SAOH treatment produced the most hydrophilic surface, whereas SLA produced the most hydrophobic surface. Cell activity indicated that SLA and SMART produced significantly rougher surfaces and promoted D1 cell attachment within 1 day of culturing, whereas SAOH treatment produced moderate roughness (Ra = 1.26 μm) and accelerated the D1 cell proliferation up to 7 days after culturing. The ECH surface significantly promoted alkaline phosphatase (ALP) expression and osteocalcin (OCN) secretion in the D1 cells compared with the other surface groups. The ECH and SMART-treated Ti surfaces resulted in maximum ALP and OCN expressions during the D1 cell culture. SLA, SAOH, and SMART substrate surfaces were rougher and exhibited better cell metabolic responses during the early stage of cell attachment, proliferation, and morphologic expressions within 1 day of D1 cell culture. The D1 cells cultured on the ECH and SMART substrates exhibited higher differentiation, and higher ALP and OCN expressions after 10 days of culture. Thus, the ECH and SMART treatments promote better ability of cell mineralization in vitro, which demonstrate their great potential for clinical use. - Highlights: • Progenitor bone cells onto Ti with different modifications are characterized. • Surface roughness and hydrophilicity encourage early stage cell attachment. • Composition and surface treatments are more vital in bone cell mineralization.

  4. Interaction of progenitor bone cells with different surface modifications of titanium implant

    International Nuclear Information System (INIS)

    Chen, Wen-Cheng; Chen, Ya-Shun; Ko, Chia-Ling; Lin, Yi; Kuo, Tzu-Huang; Kuo, Hsien-Nan

    2014-01-01

    Changes in the physical and chemical properties of Ti surfaces can be attributed to cell performance, which improves surface biocompatibility. The cell proliferation, mineralization ability, and gene expression of progenitor bone cells (D1 cell) were compared on five different Ti surfaces, namely, mechanical grinding (M), electrochemical modification through potentiostatic anodization (ECH), sandblasting and acid etching (SLA), sandblasting, hydrogen peroxide treatment, and heating (SAOH), and sandblasting, alkali heating, and etching (SMART). SAOH treatment produced the most hydrophilic surface, whereas SLA produced the most hydrophobic surface. Cell activity indicated that SLA and SMART produced significantly rougher surfaces and promoted D1 cell attachment within 1 day of culturing, whereas SAOH treatment produced moderate roughness (Ra = 1.26 μm) and accelerated the D1 cell proliferation up to 7 days after culturing. The ECH surface significantly promoted alkaline phosphatase (ALP) expression and osteocalcin (OCN) secretion in the D1 cells compared with the other surface groups. The ECH and SMART-treated Ti surfaces resulted in maximum ALP and OCN expressions during the D1 cell culture. SLA, SAOH, and SMART substrate surfaces were rougher and exhibited better cell metabolic responses during the early stage of cell attachment, proliferation, and morphologic expressions within 1 day of D1 cell culture. The D1 cells cultured on the ECH and SMART substrates exhibited higher differentiation, and higher ALP and OCN expressions after 10 days of culture. Thus, the ECH and SMART treatments promote better ability of cell mineralization in vitro, which demonstrate their great potential for clinical use. - Highlights: • Progenitor bone cells onto Ti with different modifications are characterized. • Surface roughness and hydrophilicity encourage early stage cell attachment. • Composition and surface treatments are more vital in bone cell mineralization.

  5. The involvement of proteoglycans in the human plasma prekallikrein interaction with the cell surface.

    Directory of Open Access Journals (Sweden)

    Camila Lopes Veronez

    Full Text Available INTRODUCTION: The aim of this work was to evaluate the role of human plasma prekallikrein assembly and processing in cells and to determine whether proteoglycans, along with high molecular weight kininogen (H-kininogen, influence this interaction. METHODS: We used the endothelial cell line ECV304 and the epithelial cell lines CHO-K1 (wild type and CHO-745 (deficient in proteoglycans. Prekallikrein endocytosis was studied using confocal microscopy, and prekallikrein cleavage/activation was determined by immunoblotting using an antibody directed to the prekallikrein sequence C364TTKTSTR371 and an antibody directed to the entire H-kininogen molecule. RESULTS: At 37°C, prekallikrein endocytosis was assessed in the absence and presence of exogenously applied H-kininogen and found to be 1,418.4±0.010 and 1,070.3±0.001 pixels/cell, respectively, for ECV304 and 1,319.1±0.003 and 631.3±0.001 pixels/cell, respectively, for CHO-K1. No prekallikrein internalization was observed in CHO-745 in either condition. Prekallikrein colocalized with LysoTracker in the absence and presence of exogenous H-kininogen at levels of 76.0% and 88.5%, respectively, for ECV304 and at levels of 40.7% and 57.0%, respectively, for CHO-K1. After assembly on the cell surface, a plasma kallikrein fragment of 53 kDa was predominant in the incubation buffer of all the cell lines studied, indicating specific proteolysis; plasma kallikrein fragments of 48-44 kDa and 34-32 kDa were also detected in the incubation buffer, indicating non-specific cleavage. Bradykinin free H-kininogen internalization was not detected in CHO-K1 or CHO-745 cells at 37°C. CONCLUSION: The prekallikrein interaction with the cell surface is temperature-dependent and independent of exogenously applied H-kininogen, which results in prekallikrein endocytosis promoted by proteoglycans. Prekallikrein proteolysis/activation is influenced by H-kininogen/glycosaminoglycans assembly and controls plasma kallikrein

  6. Curcumin induced nanoscale CD44 molecular redistribution and antigen-antibody interaction on HepG2 cell surface

    Energy Technology Data Exchange (ETDEWEB)

    Wang Mu [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Ruan Yuxia [Department of Ophthalmology, The First Affiliated Hospital, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Xing Xiaobo; Chen Qian; Peng, Yuan [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Cai Jiye, E-mail: tjycai@jnu.edu.cn [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China)

    2011-07-04

    Graphical abstract: Highlights: > In this study, we investigate the changes of CD44 expression and distribution on HepG2 cells after curcumin treatment. > We find curcumin is able to change the morphology and ultrastructure of HepG2 cells. > Curcumin can reduce the expression of CD44 molecules and induce the nanoscale molecular redistribution on cell surface. > The binding force between CD44-modified AFM tip and the HepG2 cell surface decreases after curcumin-treatment. - Abstract: The cell surface glycoprotein CD44 was implicated in the progression, metastasis and apoptosis of certain human tumors. In this study, we used atomic force microscope (AFM) to monitor the effect of curcumin on human hepatocellular carcinoma (HepG2) cell surface nanoscale structure. High-resolution imaging revealed that cell morphology and ultrastructure changed a lot after being treated with curcumin. The membrane average roughness increased (10.88 {+-} 4.62 nm to 129.70 {+-} 43.72 nm) and the expression of CD44 decreased (99.79 {+-} 0.16% to 75.14 {+-} 8.37%). Laser scanning confocal microscope (LSCM) imaging showed that CD44 molecules were located on the cell membrane. The florescence intensity in control group was weaker than that in curcumin treated cells. Most of the binding forces between CD44 antibodies and untreated HepG2 cell membrane were around 120-220 pN. After being incubated with curcumin, the major forces focused on 70-150 pN (10 {mu}M curcumin-treated) and 50-120 pN (20 {mu}M curcumin-treated). These results suggested that, as result of nanoscale molecular redistribution, changes of the cell surface were in response to external treatment of curcumin. The combination of AFM and LSCM could be a powerful method to detect the distribution of cell surface molecules and interactions between molecules and their ligands.

  7. Curcumin induced nanoscale CD44 molecular redistribution and antigen-antibody interaction on HepG2 cell surface

    International Nuclear Information System (INIS)

    Wang Mu; Ruan Yuxia; Xing Xiaobo; Chen Qian; Peng, Yuan; Cai Jiye

    2011-01-01

    Graphical abstract: Highlights: → In this study, we investigate the changes of CD44 expression and distribution on HepG2 cells after curcumin treatment. → We find curcumin is able to change the morphology and ultrastructure of HepG2 cells. → Curcumin can reduce the expression of CD44 molecules and induce the nanoscale molecular redistribution on cell surface. → The binding force between CD44-modified AFM tip and the HepG2 cell surface decreases after curcumin-treatment. - Abstract: The cell surface glycoprotein CD44 was implicated in the progression, metastasis and apoptosis of certain human tumors. In this study, we used atomic force microscope (AFM) to monitor the effect of curcumin on human hepatocellular carcinoma (HepG2) cell surface nanoscale structure. High-resolution imaging revealed that cell morphology and ultrastructure changed a lot after being treated with curcumin. The membrane average roughness increased (10.88 ± 4.62 nm to 129.70 ± 43.72 nm) and the expression of CD44 decreased (99.79 ± 0.16% to 75.14 ± 8.37%). Laser scanning confocal microscope (LSCM) imaging showed that CD44 molecules were located on the cell membrane. The florescence intensity in control group was weaker than that in curcumin treated cells. Most of the binding forces between CD44 antibodies and untreated HepG2 cell membrane were around 120-220 pN. After being incubated with curcumin, the major forces focused on 70-150 pN (10 μM curcumin-treated) and 50-120 pN (20 μM curcumin-treated). These results suggested that, as result of nanoscale molecular redistribution, changes of the cell surface were in response to external treatment of curcumin. The combination of AFM and LSCM could be a powerful method to detect the distribution of cell surface molecules and interactions between molecules and their ligands.

  8. Correlation of cell surface proteins of distinct Beauveria bassiana cell types and adaption to varied environment and interaction with the host insect.

    Science.gov (United States)

    Yang, Zhi; Jiang, Hongyan; Zhao, Xin; Lu, Zhuoyue; Luo, Zhibing; Li, Xuebing; Zhao, Jing; Zhang, Yongjun

    2017-02-01

    The insect fungal pathogen Beauveria bassiana produces a number of distinct cell types that include aerial conidia, blastospores and haemolymph-derived cells, termed hyphal bodies, to adapt varied environment niches and within the host insect. These cells display distinct biochemical properties and surface structures, and a highly ordered outermost brush-like structure uniquely present on hyphal bodies, but not on any in vitro cells. Here, we found that the outermost structure on the hyphal bodies mainly consisted of proteins associated to structural wall components in that most of it could be removed by dithiothreitol (DTT) or proteinase K. DTT-treatment also caused delayed germination, decreased tolerance to ultraviolet irradiation and virulence of conidia or blastospores, with decreased adherence and alternated carbohydrate epitopes, suggesting involvement in fungal development, stress responses and virulence. To characterize these cell surface molecules, proteins were released from the living cells using DTT, and identified and quantitated using label-free quantitative mass spectrometry. Thereafter, a series of bioinformatics programs were used to predict cell surface-associated proteins (CSAPs), and 96, 166 and 54 CSAPs were predicted from the identified protein pools of conidia, blastospores and hyphal bodies, respectively, which were involved in utilization of carbohydrate, nitrogen, and lipid, detoxification, pathogen-host interaction, and likely other cellular processes. Thirteen, sixty-nine and six CSAPs were exclusive in conidia, blastospores and hyphal bodies, respectively, which were verified by eGFP-tagged proteins at their N-terminus. Our data provide a crucial cue to understand mechanism of B. bassiana to adapt to varied environment and interaction with insect host. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Investigating biomolecular recognition at the cell surface using atomic force microscopy.

    Science.gov (United States)

    Wang, Congzhou; Yadavalli, Vamsi K

    2014-05-01

    Probing the interaction forces that drive biomolecular recognition on cell surfaces is essential for understanding diverse biological processes. Force spectroscopy has been a widely used dynamic analytical technique, allowing measurement of such interactions at the molecular and cellular level. The capabilities of working under near physiological environments, combined with excellent force and lateral resolution make atomic force microscopy (AFM)-based force spectroscopy a powerful approach to measure biomolecular interaction forces not only on non-biological substrates, but also on soft, dynamic cell surfaces. Over the last few years, AFM-based force spectroscopy has provided biophysical insight into how biomolecules on cell surfaces interact with each other and induce relevant biological processes. In this review, we focus on describing the technique of force spectroscopy using the AFM, specifically in the context of probing cell surfaces. We summarize recent progress in understanding the recognition and interactions between macromolecules that may be found at cell surfaces from a force spectroscopy perspective. We further discuss the challenges and future prospects of the application of this versatile technique. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Focal adhesions and cell-matrix interactions

    DEFF Research Database (Denmark)

    Woods, A; Couchman, J R

    1988-01-01

    Focal adhesions are areas of cell surfaces where specializations of cytoskeletal, membrane and extracellular components combine to produce stable cell-matrix interactions. The morphology of these adhesions and the components identified in them are discussed together with possible mechanisms...

  11. The influence of surface integrin binding patterns on specific biomaterial-cell interactions

    Science.gov (United States)

    Beranek, Maggi Marie

    As the future of biomaterials progresses toward bioactivity, the biomaterial surface must control non-specific protein adsorption and encourage selective protein and cell adsorption. Integrins alphavbeta3, alpha 1beta1, alpha5beta1 and alpha Mbeta2 are expressed on cells involved in endothelialization, inflammation, and intimal hyperplasia. These cellular events play a vital role in biomaterial biocompatibility, especially in the vascular environment. The overall hypothesis of these studies is that biomaterial surfaces exhibit selective integrin binding, which then specifies differential cell binding. To test this hypothesis, four specific aims were developed. The first aim was designed to determine whether metal and polymeric biomaterials exhibit selective integrin binding. The tested materials included 316L stainless steel, nitinol, gold, Elgiloy RTM, poly(D, L-lactide-co-glycolide), polycarbonate urethane and expanded polytetrafluoroethylene. Discrete integrin binding patterns were detected microscopically using integrin specific fluorescent antibodies. Stainless steel exhibited high level integrin alpha1beta 1 and low level integrin alphaMbeta2 binding pattern. This suggests that this metal surface should selectively encourage endothelial cell to inflammatory cell binding. In contrast, gold bound ten times the amount of integrin alphaMbeta2 compared to integrin alpha1beta1, which should encourage inflammatory cell adhesion. The 65/35 poly(D, L-lactide-co-glycolide) was the only polymeric biomaterial tested that had integrin binding levels comparable to metal biomaterials. Based on these observations, a combinational biomaterial with a surface pattern of 65/35 poly(D, L-lactide-co-glycolide) dots on a 316L stainless steel background was created. A pattern of high level integrin alpha1beta1 binding and low level integrin alpha Mbeta2 binding on this combinational surface indicates that this surface should selectively favor endothelial cell binding. In the second

  12. Cell Surface Enzymatic Engineering-Based Approaches to Improve Cellular Therapies

    KAUST Repository

    AbuElela, Ayman; Sakashita, Kosuke; Merzaban, Jasmeen

    2014-01-01

    The cell surface represents the interface between the cell and its environment. As such, the cell surface controls cell–cell interactions and functions such as adhesion and migration, and will transfer external cues to regulate processes

  13. Attachment of Salmonella strains to a plant cell wall model is modulated by surface characteristics and not by specific carbohydrate interactions.

    Science.gov (United States)

    Tan, Michelle Sze-Fan; Moore, Sean C; Tabor, Rico F; Fegan, Narelle; Rahman, Sadequr; Dykes, Gary A

    2016-09-15

    Processing of fresh produce exposes cut surfaces of plant cell walls that then become vulnerable to human foodborne pathogen attachment and contamination, particularly by Salmonella enterica. Plant cell walls are mainly composed of the polysaccharides cellulose, pectin and hemicelluloses (predominantly xyloglucan). Our previous work used bacterial cellulose-based plant cell wall models to study the interaction between Salmonella and the various plant cell wall components. We demonstrated that Salmonella attachment was favoured in the presence of pectin while xyloglucan had no effect on its attachment. Xyloglucan significantly increased the attachment of Salmonella cells to the plant cell wall model only when it was in association with pectin. In this study, we investigate whether the plant cell wall polysaccharides mediate Salmonella attachment to the bacterial cellulose-based plant cell wall models through specific carbohydrate interactions or through the effects of carbohydrates on the physical characteristics of the attachment surface. We found that none of the monosaccharides that make up the plant cell wall polysaccharides specifically inhibit Salmonella attachment to the bacterial cellulose-based plant cell wall models. Confocal laser scanning microscopy showed that Salmonella cells can penetrate and attach within the tightly arranged bacterial cellulose network. Analysis of images obtained from atomic force microscopy revealed that the bacterial cellulose-pectin-xyloglucan composite with 0.3 % (w/v) xyloglucan, previously shown to have the highest number of Salmonella cells attached to it, had significantly thicker cellulose fibrils compared to other composites. Scanning electron microscopy images also showed that the bacterial cellulose and bacterial cellulose-xyloglucan composites were more porous when compared to the other composites containing pectin. Our study found that the attachment of Salmonella cells to cut plant cell walls was not mediated by

  14. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Sourav, E-mail: sourav.bhattacharjee@wur.nl [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Opstal, Edward J. van; Alink, Gerrit M. [Wageningen University, Division of Toxicology (Netherlands); Marcelis, Antonius T. M.; Zuilhof, Han [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Rietjens, Ivonne M. C. M. [Wageningen University, Division of Toxicology (Netherlands)

    2013-06-15

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size {approx}45 nm) and polystyrene nanoparticles (PSNPs/size {approx}50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  15. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Science.gov (United States)

    Bhattacharjee, Sourav; van Opstal, Edward J.; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

    2013-06-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size 45 nm) and polystyrene nanoparticles (PSNPs/size 50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  16. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    International Nuclear Information System (INIS)

    Bhattacharjee, Sourav; Opstal, Edward J. van; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

    2013-01-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size ∼45 nm) and polystyrene nanoparticles (PSNPs/size ∼50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  17. Tumor cell surface proteins

    International Nuclear Information System (INIS)

    Kennel, S.J.; Braslawsky, G.R.; Flynn, K.; Foote, L.J.; Friedman, E.; Hotchkiss, J.A.; Huang, A.H.L.; Lankford, P.K.

    1982-01-01

    Cell surface proteins mediate interaction between cells and their environment. Unique tumor cell surface proteins are being identified and quantified in several tumor systems to address the following questions: (i) how do tumor-specific proteins arise during cell transformation; (ii) can these proteins be used as markers of tumor cell distribution in vivo; (iii) can cytotoxic drugs be targeted specifically to tumor cells using antibody; and (iv) can solid state radioimmunoassay of these proteins provide a means to quantify transformation frequencies. A tumor surface protein of 180,000 M/sub r/ (TSP-180) has been identified on cells of several lung carcinomas of BALB/c mice. TSP-180 was not detected on normal lung tissue, embryonic tissue, or other epithelial or sarcoma tumors, but it was found on lung carcinomas of other strains of mice. Considerable amino acid sequence homology exists among TSP-180's from several cell sources, indicating that TSP-180 synthesis is directed by normal cellular genes although it is not expressed in normal cells. The regulation of synthesis of TSP-180 and its relationship to normal cell surface proteins are being studied. Monoclonal antibodies (MoAb) to TSP-180 have been developed. The antibodies have been used in immunoaffinity chromatography to isolate TSP-180 from tumor cell sources. This purified tumor antigen was used to immunize rats. Antibody produced by these animals reacted at different sites (epitopes) on the TSP-180 molecule than did the original MoAb. These sera and MoAb from these animals are being used to identify normal cell components related to the TSP-180 molecule

  18. Interaction of Mycobacterium leprae with human airway epithelial cells: adherence, entry, survival, and identification of potential adhesins by surface proteome analysis.

    Science.gov (United States)

    Silva, Carlos A M; Danelishvili, Lia; McNamara, Michael; Berredo-Pinho, Márcia; Bildfell, Robert; Biet, Franck; Rodrigues, Luciana S; Oliveira, Albanita V; Bermudez, Luiz E; Pessolani, Maria C V

    2013-07-01

    This study examined the in vitro interaction between Mycobacterium leprae, the causative agent of leprosy, and human alveolar and nasal epithelial cells, demonstrating that M. leprae can enter both cell types and that both are capable of sustaining bacterial survival. Moreover, delivery of M. leprae to the nasal septum of mice resulted in macrophage and epithelial cell infection in the lung tissue, sustaining the idea that the airways constitute an important M. leprae entry route into the human body. Since critical aspects in understanding the mechanisms of infection are the identification and characterization of the adhesins involved in pathogen-host cell interaction, the nude mouse-derived M. leprae cell surface-exposed proteome was studied to uncover potentially relevant adhesin candidates. A total of 279 cell surface-exposed proteins were identified based on selective biotinylation, streptavidin-affinity purification, and shotgun mass spectrometry; 11 of those proteins have been previously described as potential adhesins. In vitro assays with the recombinant forms of the histone-like protein (Hlp) and the heparin-binding hemagglutinin (HBHA), considered to be major mycobacterial adhesins, confirmed their capacity to promote bacterial attachment to epithelial cells. Taking our data together, they suggest that the airway epithelium may act as a reservoir and/or portal of entry for M. leprae in humans. Moreover, our report sheds light on the potentially critical adhesins involved in M. leprae-epithelial cell interaction that may be useful in designing more effective tools for leprosy control.

  19. Tritium-surface interactions

    International Nuclear Information System (INIS)

    Kirkaldy, J.S.

    1983-06-01

    The report deals broadly with tritium-surface interactions as they relate to a fusion power reactor enterprise, viz., the vacuum chamber, first wall, peripherals, pumping, fuel recycling, isotope separation, repair and maintenance, decontamination and safety. The main emphasis is on plasma-surface interactions and the selection of materials for fusion chamber duty. A comprehensive review of the international (particularly U.S.) research and development is presented based upon a literature review (about 1 000 reports and papers) and upon visits to key laboratories, Sandia, Albuquerque, Sandia, Livermore and EGβG Idaho. An inventory of Canadian expertise and facilities for RβD on tritium-surface interactions is also presented. A number of proposals are made for the direction of an optimal Canadian RβD program, emphasizing the importance of building on strength in both the technological and fundamental areas. A compendium of specific projects and project areas is presented dealing primarily with plasma-wall interactions and permeation, anti-permeation materials and surfaces and health, safety and environmental considerations. Potential areas of industrial spinoff are identified

  20. Charge carrier dynamics and surface plasmon interaction in gold nanorod-blended organic solar cell

    International Nuclear Information System (INIS)

    Rana, Aniket; Lochan, Abhiram; Chand, Suresh; Kumar, Mahesh; Singh, Rajiv K.; Gupta, Neeraj; Sharma, G. D.

    2016-01-01

    The inclusion of plasmonic nanoparticles into organic solar cell enhances the light harvesting properties that lead to higher power conversion efficiency without altering the device configuration. This work defines the consequences of the nanoparticle overloading amount and energy transfer process between gold nanorod and polymer (active matrix) in organic solar cells. We have studied the hole population decay dynamics coupled with gold nanorods loading amount which provides better understanding about device performance limiting factors. The exciton and plasmon together act as an interacting dipole; however, the energy exchange between these two has been elucidated via plasmon resonance energy transfer (PRET) mechanism. Further, the charge species have been identified specifically with respect to their energy levels appearing in ultrafast time domain. The specific interaction of these charge species with respective surface plasmon resonance mode, i.e., exciton to transverse mode of oscillation and polaron pair to longitudinal mode of oscillations, has been explained. Thus, our analysis reveals that PRET enhances the carrier population density in polymer via non-radiative process beyond the concurrence of a particular plasmon resonance oscillation mode and polymer absorption range. These findings give new insight and reveal specifically the factors that enhance and control the performance of gold nanorods blended organic solar cells. This work would lead in the emergence of future plasmon based efficient organic electronic devices.

  1. Charge carrier dynamics and surface plasmon interaction in gold nanorod-blended organic solar cell

    Science.gov (United States)

    Rana, Aniket; Gupta, Neeraj; Lochan, Abhiram; Sharma, G. D.; Chand, Suresh; Kumar, Mahesh; Singh, Rajiv K.

    2016-08-01

    The inclusion of plasmonic nanoparticles into organic solar cell enhances the light harvesting properties that lead to higher power conversion efficiency without altering the device configuration. This work defines the consequences of the nanoparticle overloading amount and energy transfer process between gold nanorod and polymer (active matrix) in organic solar cells. We have studied the hole population decay dynamics coupled with gold nanorods loading amount which provides better understanding about device performance limiting factors. The exciton and plasmon together act as an interacting dipole; however, the energy exchange between these two has been elucidated via plasmon resonance energy transfer (PRET) mechanism. Further, the charge species have been identified specifically with respect to their energy levels appearing in ultrafast time domain. The specific interaction of these charge species with respective surface plasmon resonance mode, i.e., exciton to transverse mode of oscillation and polaron pair to longitudinal mode of oscillations, has been explained. Thus, our analysis reveals that PRET enhances the carrier population density in polymer via non-radiative process beyond the concurrence of a particular plasmon resonance oscillation mode and polymer absorption range. These findings give new insight and reveal specifically the factors that enhance and control the performance of gold nanorods blended organic solar cells. This work would lead in the emergence of future plasmon based efficient organic electronic devices.

  2. Regulation of epithelial and lymphocyte cell adhesion by adenosine deaminase-CD26 interaction.

    Science.gov (United States)

    Ginés, Silvia; Mariño, Marta; Mallol, Josefa; Canela, Enric I; Morimoto, Chikao; Callebaut, Christian; Hovanessian, Ara; Casadó, Vicent; Lluis, Carmen; Franco, Rafael

    2002-01-01

    The extra-enzymic function of cell-surface adenosine deaminase (ADA), an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes, B cells and T cells, has lately been the subject of numerous studies. Cell-surface ADA is able to transduce co-stimulatory signals in T cells via its interaction with CD26, an integral membrane protein that acts as ADA-binding protein. The aim of the present study was to explore whether ADA-CD26 interaction plays a role in the adhesion of lymphocyte cells to human epithelial cells. To meet this aim, different lymphocyte cell lines (Jurkat and CEM T) expressing endogenous, or overexpressing human, CD26 protein were tested in adhesion assays to monolayers of colon adenocarcinoma human epithelial cells, Caco-2, which express high levels of cell-surface ADA. Interestingly, the adhesion of Jurkat and CEM T cells to a monolayer of Caco-2 cells was greatly dependent on CD26. An increase by 50% in the cell-to-cell adhesion was found in cells containing higher levels of CD26. Incubation with an anti-CD26 antibody raised against the ADA-binding site or with exogenous ADA resulted in a significant reduction (50-70%) of T-cell adhesion to monolayers of epithelial cells. The role of ADA-CD26 interaction in the lymphocyte-epithelial cell adhesion appears to be mediated by CD26 molecules that are not interacting with endogenous ADA (ADA-free CD26), since SKW6.4 (B cells) that express more cell-surface ADA showed lower adhesion than T cells. Adhesion stimulated by CD26 and ADA is mediated by T cell lymphocyte function-associated antigen. A role for ADA-CD26 interaction in cell-to-cell adhesion was confirmed further in integrin activation assays. FACS analysis revealed a higher expression of activated integrins on T cell lines in the presence of increasing amounts of exogenous ADA. Taken together, these results suggest that the ADA-CD26 interaction on the cell surface has a role in lymphocyte-epithelial cell adhesion. PMID

  3. The RSV F and G glycoproteins interact to form a complex on the surface of infected cells

    International Nuclear Information System (INIS)

    Low, Kit-Wei; Tan, Timothy; Ng, Ken; Tan, Boon-Huan; Sugrue, Richard J.

    2008-01-01

    In this study, the interaction between the respiratory syncytial virus (RSV) fusion (F) protein, attachment (G) protein, and small hydrophobic (SH) proteins was examined. Immunoprecipitation analysis suggested that the F and G proteins exist as a protein complex on the surface of RSV-infected cells, and this conclusion was supported by ultracentrifugation analysis that demonstrated co-migration of surface-expressed F and G proteins. Although our analysis provided evidence for an interaction between the G and SH proteins, no evidence was obtained for a single protein complex involving all three of the virus proteins. These data suggest the existence of multiple virus glycoprotein complexes within the RSV envelope. Although the stimulus that drives RSV-mediated membrane fusion is unknown, the association between the G and F proteins suggest an indirect role for the G protein in this process

  4. Cell patterning without chemical surface modification: Cell cell interactions between printed bovine aortic endothelial cells (BAEC) on a homogeneous cell-adherent hydrogel

    Science.gov (United States)

    Chen, C. Y.; Barron, J. A.; Ringeisen, B. R.

    2006-10-01

    Cell printing offers the unique ability to directly deposit one or multiple cell types directly onto a surface without the need to chemically pre-treat the surface with lithographic methods. We utilize biological laser printing (BioLP ™) to form patterns of bovine aortic endothelial cells (BAECs) onto a homogeneous cell adherent hydrogel surface. These normal cells are shown to retain near-100% viability post-printing. In order to determine whether BAECs encountered shear and/or heat stress during printing, immunocytochemical staining experiments were performed to detect potential expression of heat shock proteins (HSP) by the deposited cells. Printed BAECs expressed HSP at levels similar to negative control cells, indicating that the BioLP process does not expose cells to damaging levels of stress. However, HSP expression was slightly higher at the highest laser energy studied, suggesting more stress was present under these extreme conditions. Printed BAECs also showed preferential asymmetric growth and migration towards each other and away from the originally printed pattern, demonstrating a retained ability for the cells to communicate post-printing.

  5. A nucleation theory of cell surface capping

    International Nuclear Information System (INIS)

    Coutsias, E.A.; Wester, M.J.; Perelson, A.S.

    1997-01-01

    We propose a new theory of cell surface capping based on the principles of nucleation. When antibody interacts with cell surface molecules, the molecules initially form small aggregates called patches that later coalesce into a large aggregate called a cap. While a cap can form by patches being pulled together by action of the cell''s cytoskeleton, in the case of some molecules, disruption of the cytoskeleton does not prevent cap formation. Diffusion of large aggregates on a cell surface is slow, and thus we propose that a cap can form solely through the diffusion of small aggregates containing just one or a few cell surface molecules. Here we consider the extreme case in which single molecules are mobile, but aggregates of all larger sizes are immobile. We show that a set of patches in equilibrium with a open-quotes seaclose quotes of free cell surface molecules can undergo a nucleation-type phase transition in which the largest patch will bind free cell surface molecules, deplete the concentration of such molecules in the open-quotes seaclose quotes and thus cause the other patches to shrink in size. We therefore show that a cap can form without patches having to move, collide with each other, and aggregate

  6. Osteoblast cell response to surface-modified carbon nanotubes

    International Nuclear Information System (INIS)

    Zhang Faming; Weidmann, Arne; Nebe, J. Barbara; Burkel, Eberhard

    2012-01-01

    In order to investigate the interaction of cells with modified multi-walled carbon nanotubes (MWCNTs) for their potential biomedical applications, the MWCNTs were chemically modified with carboxylic acid groups (–COOH), polyvinyl alcohol (PVA) polymer and biomimetic apatite on their surfaces. Additionally, human osteoblast MG-63 cells were cultured in the presence of the surface-modified MWCNTs. The metabolic activities of osteoblastic cells, cell proliferation properties, as well as cell morphology were studied. The surface modification of MWCNTs with biomimetic apatite exhibited a significant increase in the cell viability of osteoblasts, up to 67.23%. In the proliferation phases, there were many more cells in the biomimetic apatite-modified MWCNT samples than in the MWCNTs–COOH. There were no obvious changes in cell morphology in osteoblastic MG-63 cells cultured in the presence of these chemically-modified MWCNTs. The surface modification of MWCNTs with apatite achieves an effective enhancement of their biocompatibility.

  7. Electrostatic behavior of the charge-regulated bacterial cell surface.

    Science.gov (United States)

    Hong, Yongsuk; Brown, Derick G

    2008-05-06

    The electrostatic behavior of the charge-regulated surfaces of Gram-negative Escherichia coli and Gram-positive Bacillus brevis was studied using numerical modeling in conjunction with potentiometric titration and electrophoretic mobility data as a function of solution pH and electrolyte composition. Assuming a polyelectrolytic polymeric bacterial cell surface, these experimental and numerical analyses were used to determine the effective site numbers of cell surface acid-base functional groups and Ca(2+) sorption coefficients. Using effective site concentrations determined from 1:1 electrolyte (NaCl) experimental data, the charge-regulation model was able to replicate the effects of 2:1 electrolyte (CaCl(2)), both alone and as a mixture with NaCl, on the measured zeta potential using a single Ca(2+) surface binding constant for each of the bacterial species. This knowledge is vital for understanding how cells respond to changes in solution pH and electrolyte composition as well as how they interact with other surfaces. The latter is especially important due to the widespread use of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory in the interpretation of bacterial adhesion. As surface charge and surface potential both vary on a charge-regulated surface, accurate modeling of bacterial interactions with surfaces ultimately requires use of an electrostatic model that accounts for the charge-regulated nature of the cell surface.

  8. Cell Surface Enzymatic Engineering-Based Approaches to Improve Cellular Therapies

    KAUST Repository

    AbuElela, Ayman

    2014-06-06

    The cell surface represents the interface between the cell and its environment. As such, the cell surface controls cell–cell interactions and functions such as adhesion and migration, and will transfer external cues to regulate processes such as survival, death, and differentiation. Redefining the cell surface by temporarily (or permanently) modifying the molecular landscape of the plasma membrane affects the way in which the cell interacts with its environment and influences the information that is relayed into the cell along downstream signaling pathways. This chapter outlines the role of key enzymes, the glycosyltransferases, in posttranslationally modifying proteins and lipids to fine-tune cells, ability to migrate. These enzymes are critical in controlling the formation of a platform structure, sialyl Lewis x (sLex), on circulating cells that plays a central role in the recognition and recruitment by selectin counter receptors on endothelial cells that line blood vessels of tissues throughout the body. By developing methods to manipulate the activity of these enzymes and hence the cell surface structures that result, treatments can be envisioned that direct the migration of therapeutic cells to specific locations throughout the body and also to inhibit metastasis of detrimental cells such as circulating tumor cells.

  9. Response of cells on surface-induced nanopatterns: fibroblasts and mesenchymal progenitor cells.

    Science.gov (United States)

    Khor, Hwei Ling; Kuan, Yujun; Kukula, Hildegard; Tamada, Kaoru; Knoll, Wolfgang; Moeller, Martin; Hutmacher, Dietmar W

    2007-05-01

    Ultrathin films of a poly(styrene)-block-poly(2-vinylpyrindine) diblock copolymer (PS-b-P2VP) and poly(styrene)-block-poly(4-vinylpyrindine) diblock copolymer (PS-b-P4VP) were used to form surface-induced nanopattern (SINPAT) on mica. Surface interaction controlled microphase separation led to the formation of chemically heterogeneous surface nanopatterns on dry ultrathin films. Two distinct nanopatterned surfaces, namely, wormlike and dotlike patterns, were used to investigate the influence of topography in the nanometer range on cell adhesion, proliferation, and migration. Atomic force microscopy was used to confirm that SINPAT was stable under cell culture conditions. Fibroblasts and mesenchymal progenitor cells were cultured on the nanopatterned surfaces. Phase contrast and confocal laser microscopy showed that fibroblasts and mesenchymal progenitor cells preferred the densely spaced wormlike patterns. Atomic force microscopy showed that the cells remodelled the extracellular matrix differently as they migrate over the two distinctly different nanopatterns.

  10. Pheochromocytoma (PC12 Cell Response on Mechanobactericidal Titanium Surfaces

    Directory of Open Access Journals (Sweden)

    Jason V. Wandiyanto

    2018-04-01

    Full Text Available Titanium is a biocompatible material that is frequently used for making implantable medical devices. Nanoengineering of the surface is the common method for increasing material biocompatibility, and while the nanostructured materials are well-known to represent attractive substrata for eukaryotic cells, very little information has been documented about the interaction between mammalian cells and bactericidal nanostructured surfaces. In this study, we investigated the effect of bactericidal titanium nanostructures on PC12 cell attachment and differentiation—a cell line which has become a widely used in vitro model to study neuronal differentiation. The effects of the nanostructures on the cells were then compared to effects observed when the cells were placed in contact with non-structured titanium. It was found that bactericidal nanostructured surfaces enhanced the attachment of neuron-like cells. In addition, the PC12 cells were able to differentiate on nanostructured surfaces, while the cells on non-structured surfaces were not able to do so. These promising results demonstrate the potential application of bactericidal nanostructured surfaces in biomedical applications such as cochlear and neuronal implants.

  11. Role of Cytokine-Induced Glycosylation Changes in Regulating Cell Interactions and Cell Signaling in Inflammatory Diseases and Cancer

    Directory of Open Access Journals (Sweden)

    Justine H. Dewald

    2016-11-01

    Full Text Available Glycosylation is one of the most important modifications of proteins and lipids, and cell surface glycoconjugates are thought to play important roles in a variety of biological functions including cell-cell and cell-substrate interactions, bacterial adhesion, cell immunogenicity and cell signaling. Alterations of glycosylation are observed in number of diseases such as cancer and chronic inflammation. In that context, pro-inflammatory cytokines have been shown to modulate cell surface glycosylation by regulating the expression of glycosyltransferases involved in the biosynthesis of carbohydrate chains. These changes in cell surface glycosylation are also known to regulate cell signaling and could contribute to disease pathogenesis. This review summarizes our current knowledge of the glycosylation changes induced by pro-inflammatory cytokines, with a particular focus on cancer and cystic fibrosis, and their consequences on cell interactions and signaling.

  12. Interactions between β-catenin and the HSlo potassium channel regulates HSlo surface expression.

    Directory of Open Access Journals (Sweden)

    Shumin Bian

    Full Text Available The large conductance calcium-activated potassium channel alpha-subunit (Slo is widely distributed throughout the body and plays an important role in a number of diseases. Prior work has shown that Slo, through its S10 region, interacts with β-catenin, a key component of the cytoskeleton framework and the Wnt signaling pathway. However, the physiological significance of this interaction was not clear.Using a combination of proteomic and cell biology tools we show the existence of additional multiple binding sites in Slo, and explore in detail β-catenin interactions with the S10 region. We demonstrate that deletion of this region reduces Slo surface expression in HEK cells, which indicates that interaction with beta-catenin is important for Slo surface expression. This is confirmed by reduced expression of Slo in HEK cells and chicken (Gallus gallus domesticus leghorn white hair cells treated with siRNA to β-catenin. HSlo reciprocally co-immunoprecipitates with β-catenin, indicating a stable binding between these two proteins, with the S10 deletion mutant having reduced binding with β-catenin. We also observed that mutations of the two putative GSK phosphorylation sites within the S10 region affect both the surface expression of Slo and the channel's voltage and calcium sensitivities. Interestingly, expression of exogenous Slo in HEK cells inhibits β-catenin-dependent canonical Wnt signaling.These studies identify for the first time a central role for β-catenin in mediating Slo surface expression. Additionally we show that Slo overexpression can lead to downregulation of Wnt signaling.

  13. MEMS-based dynamic cell-to-cell culture platforms using electrochemical surface modifications

    International Nuclear Information System (INIS)

    Chang, Jiyoung; Lin, Liwei; Yoon, Sang-Hee; Mofrad, Mohammad R K

    2011-01-01

    MEMS-based biological platforms with the capability of both spatial placements and time releases of living cells for cell-to-cell culture experiments have been designed and demonstrated utilizing electrochemical surface modification effects. The spatial placement is accomplished by electrochemical surface modification of substrate surfaces to be either adhesive or non-adhesive for living cells. The time control is achieved by the electrical activation of the selective indium tin oxide co-culture electrode to allow the migration of living cells onto the electrode to start the cell-to-cell culture studies. Prototype devices have a three-electrode design with an electrode size of 50 × 50 µm 2 and the separation gaps of 2 µm between them. An electrical voltage of −1.5 V has been used to activate the electrodes independently and sequentially to demonstrate the dynamic cell-to-cell culture experiments of NIH 3T3 fibroblast and Madin Darby canine kidney cells. As such, this MEMS platform could be a basic yet versatile tool to characterize transient cell-to-cell interactions

  14. Assessing the Nano-Dynamics of the Cell Surface

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Chil Man [Dept. of Physiology and Biophysics, State University of New York, Buffalo (United States); Park, Ik Keun [Mechanical Engineering, Seoul National University of Technology, Seoul (Korea, Republic of); Bulter, Peter J. [Dept. of Bioengineering, The Pennsylvania State University, University Park (United States)

    2012-06-15

    It is important to know the mechanism of cell membrane fluctuation because it can be readout for the nanomechanical interaction between cytoskeleton and plasma membrane. Traditional techniques, however, have drawbacks such as probe contact with the cell surface, complicate analysis, and limit spatial and temporal resolution. In this study, we developed a new system for non-contact measurement of nano-scale localized-cell surface dynamics using modified-scanning ion-conductance microscopy. With 2 nm resolution, we determined that endothelial cells have local membrane fluctuations of -20 nm, actin depolymerization causes increase in fluctuation amplitude, and ATP depletion abolishes all membrane fluctuations.

  15. Chemical and Enzymatic Strategies for Bacterial and Mammalian Cell Surface Engineering.

    Science.gov (United States)

    Bi, Xiaobao; Yin, Juan; Chen Guanbang, Ashley; Liu, Chuan-Fa

    2018-06-07

    The cell surface serves important functions such as the regulation of cell-cell and cell-environment interactions. The understanding and manipulation of the cell surface is important for a wide range of fundamental studies of cellular behavior and for biotechnological and medical applications. With the rapid advance of biology, chemistry and materials science, many strategies have been developed for the functionalization of bacterial and mammalian cell surfaces. Here, we review the recent development of chemical and enzymatic approaches to cell surface engineering with particular emphasis on discussing the advantages and limitations of each of these strategies. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Single Cell Force Spectroscopy for Quantification of Cellular Adhesion on Surfaces

    Science.gov (United States)

    Christenson, Wayne B.

    Cell adhesion is an important aspect of many biological processes. The atomic force microscope (AFM) has made it possible to quantify the forces involved in cellular adhesion using a technique called single cell force spectroscopy (SCFS). AFM based SCFS offers versatile control over experimental conditions for probing directly the interaction between specific cell types and specific proteins, surfaces, or other cells. Transmembrane integrins are the primary proteins involved in cellular adhesion to the extra cellular matix (ECM). One of the chief integrins involved in the adhesion of leukocyte cells is alpha Mbeta2 (Mac-1). The experiments in this dissertation quantify the adhesion of Mac-1 expressing human embryonic kidney (HEK Mac-1), platelets, and neutrophils cells on substrates with different concentrations of fibrinogen and on fibrin gels and multi-layered fibrinogen coated fibrin gels. It was shown that multi-layered fibrinogen reduces the adhesion force of these cells considerably. A novel method was developed as part of this research combining total internal reflection microscopy (TIRFM) with SCFS allowing for optical microscopy of HEK Mac-1 cells interacting with bovine serum albumin (BSA) coated glass after interacting with multi-layered fibrinogen. HEK Mac-1 cells are able to remove fibrinogen molecules from the multi-layered fibrinogen matrix. An analysis methodology for quantifying the kinetic parameters of integrin-ligand interactions from SCFS experiments is proposed, and the kinetic parameters of the Mac-1 fibrinogen bond are quantified. Additional SCFS experiments quantify the adhesion of macrophages and HEK Mac-1 cells on functionalized glass surfaces and normal glass surfaces. Both cell types show highest adhesion on a novel functionalized glass surface that was prepared to induce macrophage fusion. These experiments demonstrate the versatility of AFM based SCFS, and how it can be applied to address many questions in cellular biology offering

  17. Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM.

    Science.gov (United States)

    Zhang, Wen; Stack, Andrew G; Chen, Yongsheng

    2011-02-01

    To better understand environmental behaviors of nanoparticles (NPs), we used the atomic force microscopy (AFM) to measure interaction forces between E. coli cells and NPs immobilized on surfaces in an aqueous environment. The results showed that adhesion force strength was significantly influenced by particle size for both hematite (α-Fe(2)O(3)) and corundum (α-Al(2)O(3)) NPs whereas the effect on the repulsive force was not observed. The adhesion force decreased from 6.3±0.7nN to 0.8±0.4nN as hematite NPs increased from 26nm to 98nm in diameter. Corundum NPs exhibited a similar dependence of adhesion force on particle size. The Johnson-Kendall-Roberts (JKR) model was employed to estimate the contact area between E. coli cells and NPs, and based on the JKR model a new model that considers local effective contact area was developed. The prediction of the new model matched the size dependence of adhesion force in experimental results. Size effects on adhesion forces may originate from the difference in local effective contact areas as supported by our model. These findings provide fundamental information for interpreting the environmental behaviors and biological interactions of NPs, which barely have been addressed. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Surface cell immobilization within perfluoroalkoxy microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Stojkovič, Gorazd; Krivec, Matic [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia); Vesel, Alenka [Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Marinšek, Marjan [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia); Žnidaršič-Plazl, Polona, E-mail: polona.znidarsic@fkkt.uni-lj.si [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia)

    2014-11-30

    Graphical abstract: - Highlights: • A very efficient approach for immobilization of cells into microreactors is presented. • It is applicable to various materials, including PFA and cyclic olefin (co)polymers. • It was used to immobilize different prokaryotic and eukaryotic microbes. • Cells were immobilized on the surface in high density and showed good stability. • Mechanisms of APTES interactions with target materials are proposed. - Abstract: Perfluoroalkoxy (PFA) is one of the most promising materials for the fabrication of cheap, solvent resistant and reusable microfluidic chips, which have been recently recognized as effective tools for biocatalytic process development. The application of biocatalysts significantly depends on efficient immobilization of enzymes or cells within the reactor enabling long-term biocatalyst use. Functionalization of PFA microchannels by 3-aminopropyltriethoxysilane (ATPES) and glutaraldehyde was used for rapid preparation of microbioreactors with surface-immobilized cells. X-ray photoelectron spectroscopy and scanning electron microscopy were used to accurately monitor individual treatment steps and to select conditions for cell immobilization. The optimized protocol for Saccharomyces cerevisiae immobilization on PFA microchannel walls comprised ethanol surface pretreatment, 4 h contacting with 10% APTES aqueous solution, 10 min treatment with 1% glutaraldehyde and 20 min contacting with cells in deionized water. The same protocol enabled also immobilization of Escherichia coli, Pseudomonas putida and Bacillus subtilis cells on PFA surface in high densities. Furthermore, the developed procedure has been proved to be very efficient also for surface immobilization of tested cells on other materials that are used for microreactor fabrication, including glass, polystyrene, poly (methyl methacrylate), polycarbonate, and two olefin-based polymers, namely Zeonor{sup ®} and Topas{sup ®}.

  19. Inverting adherent cells for visualizing ECM interactions at the basal cell side

    Energy Technology Data Exchange (ETDEWEB)

    Gudzenko, Tetyana [DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1a, 76131 Karlsruhe (Germany); Franz, Clemens M., E-mail: clemens.franz@kit.edu [DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1a, 76131 Karlsruhe (Germany)

    2013-05-15

    Interactions with the extracellular matrix (ECM) govern a wide range of cellular functions, including survival, migration and invasion. However, in adherent cells these interactions occur primarily on the basal cell side, making them inaccessible to high-resolution, surface-scanning imaging techniques such as atomic force microscopy (AFM) or scanning electron microscopy (SEM). Here we describe a fast and reliable method for inverting adherent cells, exposing the basal cell membrane for direct analysis by AFM or SEM in combination with fluorescence microscopy. Cells including their matrix adhesion sites remain intact during the inversion process and are transferred together with the complete array of basally associated ECM proteins. Molecular features of ECM proteins, such as the characteristic 67 nm collagen D-periodicity, are well preserved after inversion. To demonstrate the versatility of the method, we compared basal interactions of fibroblasts with fibrillar collagen I and fibronectin matrices. While fibroblasts remodel the fibronectin layer exclusively from above, they actively invade even thin collagen layers by contacting individual collagen nanofibrils both basally and apically through a network of cellular extensions. Cell–matrix entanglement coincides with enhanced cell spreading and flattening, indicating that nanoscale ECM interactions govern macroscopic changes in cell morphology. The presented cell inversion technique can thus provide novel insight into nanoscale cell–matrix interactions at the basal cell side. - Highlights: ► We present a novel method for inverting adherent cells to expose the basal cell side. ► Basal cell sides can be imaged at high resolution by AFM and SEM. ► Cells can be inverted together with the underlying extracellular matrix. ► AFM images of inverted cells provide a nanoscale look at basal cell–ECM interactions.

  20. Adhesion defective BHK cell mutant has cell surface heparan sulfate proteoglycan of altered properties

    DEFF Research Database (Denmark)

    Couchman, J R; Austria, R; Woods, A

    1988-01-01

    In the light of accumulating data that implicate cell surface heparan sulfate proteoglycans (HSPGs) with a role in cell interactions with extracellular matrix molecules such as fibronectin, we have compared the properties of these molecules in wild-type BHK cells and an adhesion-defective ricin......-resistant mutant (RicR14). Our results showed that the mutant, unlike BHK cells, cannot form focal adhesions when adherent to planar substrates in the presence of serum. Furthermore, while both cell lines possess similar amounts of cell surface HSPG with hydrophobic properties, that of RicR14 cells had decreased...... sulfation, reduced affinity for fibronectin and decreased half-life on the cell surface when compared to the normal counterpart. Our conclusions based on this data are that these altered properties may, in part, account for the adhesion defect in the ricin-resistant mutant. Whether this results from...

  1. Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions.

    Science.gov (United States)

    Khayet, Mohamed; Fernández, Victoria

    2012-11-14

    Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions.

  2. Human Skin Is the Largest Epithelial Surface for Interaction with Microbes.

    Science.gov (United States)

    Gallo, Richard L

    2017-06-01

    Human skin contains an abundant and diverse population of microbial organisms. Many of these microbes inhabit follicular structures of the skin. Furthermore, numerous studies have shown that the interaction of some members of the skin microbiome with host cells will result in changes in cell function. However, estimates of the potential for the microbiome to influence human health through skin have ignored the inner follicular surface, and therefore vastly underestimated the potential of the skin microbiome to have a systemic effect on the human body. By calculating the surface area of follicular and the interfollicular epithelial surface it is shown that skin provides a vast interface for interactions with the microbiome. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

  3. Secreted NS1 of dengue virus attaches to the surface of cells via interactions with heparan sulfate and chondroitin sulfate E.

    Directory of Open Access Journals (Sweden)

    Panisadee Avirutnan

    2007-11-01

    Full Text Available Dengue virus (DENV nonstructural protein-1 (NS1 is a secreted glycoprotein that is absent from viral particles but accumulates in the supernatant and on the plasma membrane of cells during infection. Immune recognition of cell surface NS1 on endothelial cells has been hypothesized as a mechanism for the vascular leakage that occurs during severe DENV infection. However, it has remained unclear how NS1 becomes associated with the plasma membrane, as it contains no membrane-spanning sequence motif. Using flow cytometric and ELISA-based binding assays and mutant cell lines lacking selective glycosaminoglycans, we show that soluble NS1 binds back to the surface of uninfected cells primarily via interactions with heparan sulfate and chondroitin sulfate E. DENV NS1 binds directly to the surface of many types of epithelial and mesenchymal cells yet attaches poorly to most peripheral blood cells. Moreover, DENV NS1 preferentially binds to cultured human microvascular compared to aortic or umbilical cord vein endothelial cells. This binding specificity was confirmed in situ as DENV NS1 bound to lung and liver but not intestine or brain endothelium of mouse tissues. Differential binding of soluble NS1 by tissue endothelium and subsequent recognition by anti-NS1 antibodies could contribute to the selective vascular leakage syndrome that occurs during severe secondary DENV infection.

  4. Cell surface N-glycans influence the level of functional E-cadherin at the cell–cell border

    Directory of Open Access Journals (Sweden)

    M. Kristen Hall

    2014-01-01

    Full Text Available E-cadherin is crucial for adhesion of cells to each other and thereby development and maintenance of tissue. While it is has been established that N-glycans inside the cell impact the level of E-cadherin at the cell surface of epithelial-derived cells, it is unclear whether N-glycans outside the cell control the clustering of E-cadherin at the cell–cell border. Here, we demonstrate reduction of N-glycans at the cell surface weakened the recruitment and retention of E-cadherin at the cell–cell border, and consequently reduced the strength of cell–cell interactions. We conclude that N-glycans at the cell surface are tightly linked to the placement of E-cadherin at the cell–cell border and thereby control E-cadherin mediated cell–cell adhesion.

  5. Autonomous molecular cascades for evaluation of cell surfaces

    Science.gov (United States)

    Rudchenko, Maria; Taylor, Steven; Pallavi, Payal; Dechkovskaia, Alesia; Khan, Safana; Butler, Vincent P., Jr.; Rudchenko, Sergei; Stojanovic, Milan N.

    2013-08-01

    Molecular automata are mixtures of molecules that undergo precisely defined structural changes in response to sequential interactions with inputs. Previously studied nucleic acid-based automata include game-playing molecular devices (MAYA automata) and finite-state automata for the analysis of nucleic acids, with the latter inspiring circuits for the analysis of RNA species inside cells. Here, we describe automata based on strand-displacement cascades directed by antibodies that can analyse cells by using their surface markers as inputs. The final output of a molecular automaton that successfully completes its analysis is the presence of a unique molecular tag on the cell surface of a specific subpopulation of lymphocytes within human blood cells.

  6. PREFACE: Cell-substrate interactions Cell-substrate interactions

    Science.gov (United States)

    Gardel, Margaret; Schwarz, Ulrich

    2010-05-01

    One of the most striking achievements of evolution is the ability to build cellular systems that are both robust and dynamic. Taken by themselves, both properties are obvious requirements: robustness reflects the fact that cells are there to survive, and dynamics is required to adapt to changing environments. However, it is by no means trivial to understand how these two requirements can be implemented simultaneously in a physical system. The long and difficult quest to build adaptive materials is testimony to the inherent difficulty of this goal. Here materials science can learn a lot from nature, because cellular systems show that robustness and dynamics can be achieved in a synergetic fashion. For example, the capabilities of tissues to repair and regenerate are still unsurpassed in the world of synthetic materials. One of the most important aspects of the way biological cells adapt to their environment is their adhesive interaction with the substrate. Numerous aspects of the physiology of metazoan cells, including survival, proliferation, differentiation and migration, require the formation of adhesions to the cell substrate, typically an extracellular matrix protein. Adhesions guide these diverse processes both by mediating force transmission from the cell to the substrate and by controlling biochemical signaling pathways. While the study of cell-substrate adhesions is a mature field in cell biology, a quantitative biophysical understanding of how the interactions of the individual molecular components give rise to the rich dynamics and mechanical behaviors observed for cell-substrate adhesions has started to emerge only over the last decade or so. The recent growth of research activities on cell-substrate interactions was strongly driven by the introduction of new physical techniques for surface engineering into traditional cell biological work with cell culture. For example, microcontact printing of adhesive patterns was used to show that cell fate depends

  7. Human mammary progenitor cell fate decisions are productsof interactions with combinatorial microenvironments

    DEFF Research Database (Denmark)

    LaBarge, Mark A.; Nelson, Celeste M.; Villadsen, René

    2009-01-01

    factors, ECM, and other cells, as well as physical properties of the ECM. To understand regulation of fate decisions, therefore, would require a means of understanding carefully choreographed combinatorial interactions. Here we used microenvironment protein microarrays to functionally identify...... combinations of cell-extrinsic mammary gland proteins and ECM molecules that imposed specific cell fates on bipotent human mammary progenitor cells.Micropatterned cell culture surfaces were fabricated to distinguish between the instructive effects of cell-cell versus cell-ECM interactions, as well...

  8. Identifying plant cell-surface receptors: combining 'classical' techniques with novel methods.

    Science.gov (United States)

    Uebler, Susanne; Dresselhaus, Thomas

    2014-04-01

    Cell-cell communication during development and reproduction in plants depends largely on a few phytohormones and many diverse classes of polymorphic secreted peptides. The peptide ligands are bound at the cell surface of target cells by their membranous interaction partners representing, in most cases, either receptor-like kinases or ion channels. Although knowledge of both the extracellular ligand and its corresponding receptor(s) is necessary to describe the downstream signalling pathway(s), to date only a few ligand-receptor pairs have been identified. Several methods, such as affinity purification and yeast two-hybrid screens, have been used very successfully to elucidate interactions between soluble proteins, but most of these methods cannot be applied to membranous proteins. Experimental obstacles such as low concentration and poor solubility of membrane receptors, as well as instable transient interactions, often hamper the use of these 'classical' approaches. However, over the last few years, a lot of progress has been made to overcome these problems by combining classical techniques with new methodologies. In the present article, we review the most promising recent methods in identifying cell-surface receptor interactions, with an emphasis on success stories outside the field of plant research.

  9. The interaction of bacteria and metal surfaces

    International Nuclear Information System (INIS)

    Mansfeld, Florian

    2007-01-01

    This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E corr became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V)-current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions

  10. The interaction of bacteria and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mansfeld, Florian [Corrosion and Environmental Effects Laboratory (CEEL), The Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241 (United States)

    2007-10-10

    This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E{sub corr} became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V) - current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions. (author)

  11. Layilin, a cell surface hyaluronan receptor, interacts with merlin and radixin

    International Nuclear Information System (INIS)

    Bono, Petri; Cordero, Etchell; Johnson, Kristen; Borowsky, Mark; Ramesh, Vijaya; Jacks, Tyler; Hynes, Richard O.

    2005-01-01

    Layilin is a widely expressed integral membrane hyaluronan receptor, originally identified as a binding partner of talin located in membrane ruffles. We have identified merlin, the neurofibromatosis type 2 tumor suppressor protein and radixin, as other interactors with the carboxy-terminal domain of layilin. We show that the carboxy-terminal domain of layilin is capable of binding to the amino-terminal domain of radixin. An interdomain interaction between the amino- and the carboxy-terminal domains of radixin inhibits its ability to bind to layilin. In the presence of acidic phospholipids, the interdomain interaction of radixin is inhibited and layilin can bind to full-length radixin. In contrast, layilin binds both full-length and amino-terminal merlin-GST fusion proteins without a requirement for phospholipids. Furthermore, layilin antibody can immunoprecipitate merlin, confirming association in vivo between these two proteins, which also display similar subcellular localizations in ruffling membranes. No interaction was observed between layilin and ezrin or layilin and moesin. These findings expand the known binding partners of layilin to include other members of the talin/band 4.1/ERM (ezrin, radixin, and moesin) family of cytoskeletal-membrane linker molecules. This in turn suggests that layilin may mediate signals from extracellular matrix to the cell cytoskeleton via interaction with different intracellular binding partners and thereby be involved in the modulation of cortical structures in the cell

  12. The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation

    KAUST Repository

    Naganuma, Tamaki

    2014-05-01

    Understanding and controlling cell proliferation on biomaterial surfaces is critical for scaffold/artificial-niche design in tissue engineering. The mechanism by which underlying integrin ligates with functionalized biomaterials to induce cell proliferation is still not completely understood. In this study, poly-l-lactide (PL) scaffold surfaces were functionalized using layers of cerium oxide nanoparticles (CNPs), which have recently attracted attention for use in therapeutic application due to their catalytic ability of Ce4+ and Ce3+ sites. To isolate the influence of Ce valance states of CNPs on cell proliferation, human mesenchymal stem cells (hMSCs) and osteoblast-like cells (MG63) were cultured on the PL/CNP surfaces with dominant Ce4+ and Ce3+ regions. Despite cell type (hMSCs and MG63 cells), different surface features of Ce4+ and Ce3+ regions clearly promoted and inhibited cell spreading, migration and adhesion behavior, resulting in rapid and slow cell proliferation, respectively. Cell proliferation results of various modified CNPs with different surface charge and hydrophobicity/hydrophilicity, indicate that Ce valence states closely correlated with the specific cell morphologies and cell-material interactions that trigger cell proliferation. This finding suggests that the cell-material interactions, which influence cell proliferation, may be controlled by introduction of metal elements with different valence states onto the biomaterial surface. © 2014 Elsevier Ltd.

  13. Surface free energy predominates in cell adhesion to hydroxyapatite through wettability.

    Science.gov (United States)

    Nakamura, Miho; Hori, Naoko; Ando, Hiroshi; Namba, Saki; Toyama, Takeshi; Nishimiya, Nobuyuki; Yamashita, Kimihiro

    2016-05-01

    The initial adhesion of cells to biomaterials is critical in the regulation of subsequent cell behaviors. The purpose of this study was to investigate a mechanism through which the surface wettability of biomaterials can be improved and determine the effects of biomaterial surface characteristics on cellular behaviors. We investigated the surface characteristics of various types of hydroxyapatite after sintering in different atmospheres and examined the effects of various surface characteristics on cell adhesion to study cell-biomaterial interactions. Sintering atmosphere affects the polarization capacity of hydroxyapatite by changing hydroxide ion content and grain size. Compared with hydroxyapatite sintered in air, hydroxyapatite sintered in saturated water vapor had a higher polarization capacity that increased surface free energy and improved wettability, which in turn accelerated cell adhesion. We determined the optimal conditions of hydroxyapatite polarization for the improvement of surface wettability and acceleration of cell adhesion. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Interaction of VLA-5 Molecule With Rheumatoid Articular Cartilage Surface : An Electron Microscopic Evidence of Expression of VLA-5 on Pannus Invading Cells

    OpenAIRE

    Ishikawa, Hitoshi; Hirata, Souichirou; Saura, Ryuuichi; Andoh, Yoshihiro; Mizuno, Kosaku

    1998-01-01

    Pannus is made up mainly of fibroblasts, macrophages and lymphocytes. VLA-5 positive cells are present in the pannus in large numbers. It is likely that the tissue distribution of infiltrated cells derived from post-capillary venules is influenced by the ECM of the pannus and the ability of these cells to interact with the ECM through surface receptor expression. VLA-5 molecules are the predominant (31 integrins expressed by synovial pannus. Since the VLA integrins function as fibronectin rec...

  15. Basigin-2 Is a Cell Surface Receptor for Soluble Basigin Ligand*S⃞

    Science.gov (United States)

    Belton, Robert J.; Chen, Li; Mesquita, Fernando S.; Nowak, Romana A.

    2008-01-01

    The metastatic spread of a tumor is dependent upon the ability of the tumor to stimulate surrounding stromal cells to express enzymes required for tissue remodeling. The immunoglobulin superfamily protein basigin (EMMPRIN/CD147) is a cell surface glycoprotein expressed by tumor cells that stimulates matrix metalloproteinase and vascular endothelial growth factor expression in stromal cells. The ability of basigin to stimulate expression of molecules involved in tissue remodeling and angiogenesis makes basigin a potential target for the development of strategies to block metastasis. However, the identity of the cell surface receptor for basigin remains controversial. The goal of this study was to determine the identity of the receptor for basigin. Using a novel recombinant basigin protein (rBSG) corresponding to the extracellular domain of basigin, it was demonstrated that the native, nonglycosylated rBSG protein forms dimers in solution. Furthermore, rBSG binds to the surface of uterine fibroblasts, activates the ERK1/2 signaling pathway, and induces expression of matrix metalloproteinases 1, 2, and 3. Proteins that interact with rBSG were isolated using a biotin label transfer technique and sequenced by matrix-assisted laser desorption ionization tandem mass spectrophotometry. The results demonstrate that rBSG interacts with basigin expressed on the surface of fibroblasts and is subsequently internalized. During internalization, rBSG associates with a novel form of human basigin (basigin-3). It was concluded that cell surface basigin functions as a membrane receptor for soluble basigin and this homophilic interaction is not dependent upon glycosylation of the basigin ligand. PMID:18434307

  16. The effect of cell surface components on adhesion ability of Lactobacillus rhamnosus.

    Science.gov (United States)

    Polak-Berecka, Magdalena; Waśko, Adam; Paduch, Roman; Skrzypek, Tomasz; Sroka-Bartnicka, Anna

    2014-10-01

    The aim of this study was to analyze the cell envelope components and surface properties of two phenotypes of Lactobacillus rhamnosus isolated from the human gastrointestinal tract. The ability of the bacteria to adhere to human intestinal cells and to aggregate with other bacteria was determined. L. rhamnosus strains E/N and PEN differed with regard to the presence of exopolysaccharides (EPS) and specific surface proteins. Transmission electron microscopy showed differences in the structure of the outer cell surface of the strains tested. Bacterial surface properties were analyzed by Fourier transform infrared spectroscopy, fatty acid methyl esters and hydrophobicity assays. Aggregation capacity and adhesion of the tested strains to the human colon adenocarcinoma cell line HT29 was determined. The results indicated a high adhesion and aggregation ability of L. rhamnosus PEN, which possessed specific surface proteins, had a unique fatty acid content, and did not synthesize EPS. Adherence of L. rhamnosus was dependent on specific interactions and was promoted by surface proteins (42-114 kDa) and specific fatty acids. Polysaccharides likely hindered bacterial adhesion and aggregation by masking protein receptors. This study provides information on the cell envelope constituents of lactobacilli that influence bacterial aggregation and adhesion to intestinal cells. This knowledge will help to understand better their specific contribution in commensal-host interactions and adaptation to this ecological niche.

  17. Influence of surfaces modified with biomimetic extracellular matrices on adhesion and proliferation of mesenchymal stem cells and osteosarcoma cells.

    Science.gov (United States)

    Cai, Rong; Kawazoe, Naoki; Chen, Guoping

    2015-02-01

    Preparation of surfaces modified with biomimetic extracellular matrices (ECMs) is important for investigation of the interaction between ECMs and cells. In the present study, surfaces modified with ECMs from normal somatic cells, stem cells and tumor cells were prepared by cell culture method. The ECMs derived from bone marrow-derived mesenchymal stem cells (MSCs), dermal fibroblasts (FBs), osteoblasts (OBs) and MG63 osteosarcoma cells were deposited on the surfaces of cell-culture polystyrene plates (TCPS). The ECMs from different cell types had different compositions. The effects of the ECM-deposited surfaces on the adhesion, spreading and proliferation of MSCs and MG63 human osteosarcoma cells were dependent on the type of both ECMs and cells. The surfaces deposited with ECMs from MSCs, FBs and OBs promoted cell adhesion more strongly than surfaces deposited with ECMs from MG63 cells and TCPS. Compared to TCPS, the ECM-deposited surfaces promoted proliferation of MSCs while they inhibited the proliferation of MG63 cells. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Efficient Isolation and Quantitative Proteomic Analysis of Cancer Cell Plasma Membrane Proteins for Identification of Metastasis-Associated Cell Surface Markers

    DEFF Research Database (Denmark)

    Lund, Rikke; Leth-Larsen, Rikke; Jensen, Ole N

    2009-01-01

    Cell surface membrane proteins are involved in central processes such as cell signaling, cell-cell interactions, ion and solute transport, and they seem to play a pivotal role in several steps of the metastatic process of cancer cells. The low abundance and hydrophobic nature of cell surface...... membrane proteins complicate their purification and identification by MS. We used two isogenic cell lines with opposite metastatic capabilities in nude mice to optimize cell surface membrane protein purification and to identify potential novel markers of metastatic cancer. The cell surface membrane...... proteins were isolated by centrifugation/ultracentrifugation steps, followed by membrane separation using a Percoll/sucrose density gradient. The gradient fractions containing the cell surface membrane proteins were identified by enzymatic assays. Stable isotope labeling of the proteome of the metastatic...

  19. MICROBIAL CELL-SURFACE HYDROPHOBICITY - THE INVOLVEMENT OF ELECTROSTATIC INTERACTIONS IN MICROBIAL ADHESION TO HYDROCARBONS (MATH)

    NARCIS (Netherlands)

    GEERTSEMADOORNBUSCH, GI; VANDERMEI, HC; BUSSCHER, HJ

    Microbial adhesion to hydrocarbons (MATH) is the most commonly used method to determine microbial cell surface hydrophobicity. Since, however, the assay is based on adhesion, it is questionable whether the results reflect only the cell surface hydrophobicity or an interplay of hydrophobicity and

  20. Interacting boson model with surface delta interaction between nucleons

    International Nuclear Information System (INIS)

    Druce, C.; Moszkowski, S.A.

    1984-01-01

    The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. The authors have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson proton-boson interaction for the case of degenerate orbits

  1. InterProSurf: a web server for predicting interacting sites on protein surfaces

    Science.gov (United States)

    Negi, Surendra S.; Schein, Catherine H.; Oezguen, Numan; Power, Trevor D.; Braun, Werner

    2009-01-01

    Summary A new web server, InterProSurf, predicts interacting amino acid residues in proteins that are most likely to interact with other proteins, given the 3D structures of subunits of a protein complex. The prediction method is based on solvent accessible surface area of residues in the isolated subunits, a propensity scale for interface residues and a clustering algorithm to identify surface regions with residues of high interface propensities. Here we illustrate the application of InterProSurf to determine which areas of Bacillus anthracis toxins and measles virus hemagglutinin protein interact with their respective cell surface receptors. The computationally predicted regions overlap with those regions previously identified as interface regions by sequence analysis and mutagenesis experiments. PMID:17933856

  2. Bone cell-material interactions on metal-ion doped polarized hydroxyapatite

    International Nuclear Information System (INIS)

    Bodhak, Subhadip; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    The objective of this work is to study the influence of Mg 2+ and Sr 2+ dopants on in vitro bone cell-material interactions of electrically polarized hydroxyapatite [HAp, Ca 10 (PO 4 ) 6 (OH) 2 ] ceramics with an aim to achieve additional advantage of matching bone chemistry along with the original benefits of electrical polarization treatment relevant to biomedical applications. To achieve our research objective, commercial phase pure HAp has been doped with MgO, and SrO in single, and binary compositions. All samples have been sintered at 1200 deg. C for 2 h and subsequently polarized using an external d.c. field (2.0 kV/cm) at 400 deg. C for 1 h. Combined addition of 1 wt.% MgO/1 wt.% SrO in HAp has been most beneficial in enhancing the polarizability in which stored charge was 4.19 μC/cm 2 compared to pure HAp of 2.23 μC/cm 2 . Bone cell-material interaction has been studied by culturing with human fetal osteoblast cells (hFOB) for a maximum of 7 days. Scanning electron microscope (SEM) images of cell morphology reveal that favorable surface properties and dopant chemistry lead to good cellular adherence and spreading on negatively charged surfaces of both Sr 2+ and Mg 2+ doped HAp samples over undoped HAp. MTT assay results at 7 days show the highest viable cell densities on the negatively charged surfaces of binary doped HAp samples, while positive charged doped HAp surfaces exhibit limited cellular growth in comparison to neutral surfaces.

  3. Interaction of human mesenchymal stem cells with osteopontin coated hydroxyapatite surfaces

    DEFF Research Database (Denmark)

    Jensen, Thomas; Dolatshahi-Pirouz, Alireza; Foss, Morten

    2010-01-01

    In vitro studies of the initial attachment, spreading and motility of human bone mesenchymal stem cells have been carried out on bovine osteopontin (OPN) coated hydroxyapatite (HA) and gold (Au) model surfaces. The adsorption of OPN extracted from bovine milk was monitored by the quartz crystal...

  4. Effects of Surface Morphology ZnAl2O4 of Ceramic Materials on Osteoblastic Cells Responses

    International Nuclear Information System (INIS)

    Suarez-Franco, J.L.; Fernandez-Pedrero, J.A.; Ivarez-Perez, M.A.; Garcia-Hipolito, M.; Surarez-Rosales, M.; Fregoso, O.; Juarez-Islas, J.A.; Ivarez-Perez, M.A.

    2013-01-01

    Ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. The purpose of this study was to investigate the effect of surface morphology of nano structure thin films of ZnAl 2 O 4 prepared by spray pyrolysis and bulk pellets of polycrystalline ZnAl 2 O 4 prepared by chemical coprecipitation reaction on the in vitro cell adhesion, viability, and cell-material interactions of osteoblastic cells. Our result showed that cell attachment was significantly enhanced from 60 to 80% on the ZnAl 2 O 4 nano structured material surface when compared with bulk ceramic surfaces. Moreover, our results showed that the balance of morphological properties of the thin film nano structure ceramic improves cell-material interaction with enhanced spreading and filopodia with multiple cellular extensions on the surface of the ceramic and enhancing cell viability/proliferation in comparison with bulk ceramic surfaces used as control. Altogether, these results suggest that zinc aluminate nano structured materials have a great potential to be used in dental implant and bone substitute applications.Ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. The purpose of this study was to investigate the effect of surface morphology of nano structure thin films of ZnAl 2 O 4 prepared by spray pyrolysis and bulk pellets of polycrystalline ZnAl 2 O 4 prepared by chemical coprecipitation reaction on the in vitro cell adhesion, viability, and cell-material interactions of osteoblastic cells. Our result showed that cell attachment was significantly enhanced from 60 to 80% on the ZnAl 2 O 4 nano structured material surface when compared with bulk ceramic surfaces. Moreover, our results showed that the balance of morphological properties of the thin film nano structure ceramic improves

  5. Numerical simulation of ion-surface interactions

    International Nuclear Information System (INIS)

    Hou, M.

    1994-01-01

    This paper, based on examples from the author's contribution, aims to illustrate the role of ballistic simulations of the interaction between an ion beam and a surface in the characterization of surface properties. Several aspects of the ion-surface interaction have been modelled to various levels of sophistication by computer simulation. Particular emphasis is given to the ion scattering in the impact mode, in the multiple scattering regime and at grazing incidence, as well as to the Auger emission resulting from electronic excitation. Some examples are then given in order to illustrate the use of the combination between simulation and experiment to study the ion-surface interaction and surface properties. Ion-induced Auger emission, the determination of potentials and of overlay structures are discusse. The possibility to tackle dynamical surface properties by menas of a combination between molecular dynamics, ballistic simulations and ion scattering measurements in then briefly discussed. (orig.)

  6. CbtA toxin of Escherichia coli inhibits cell division and cell elongation via direct and independent interactions with FtsZ and MreB.

    Science.gov (United States)

    Heller, Danielle M; Tavag, Mrinalini; Hochschild, Ann

    2017-09-01

    The toxin components of toxin-antitoxin modules, found in bacterial plasmids, phages, and chromosomes, typically target a single macromolecule to interfere with an essential cellular process. An apparent exception is the chromosomally encoded toxin component of the E. coli CbtA/CbeA toxin-antitoxin module, which can inhibit both cell division and cell elongation. A small protein of only 124 amino acids, CbtA, was previously proposed to interact with both FtsZ, a tubulin homolog that is essential for cell division, and MreB, an actin homolog that is essential for cell elongation. However, whether or not the toxic effects of CbtA are due to direct interactions with these predicted targets is not known. Here, we genetically separate the effects of CbtA on cell elongation and cell division, showing that CbtA interacts directly and independently with FtsZ and MreB. Using complementary genetic approaches, we identify the functionally relevant target surfaces on FtsZ and MreB, revealing that in both cases, CbtA binds to surfaces involved in essential cytoskeletal filament architecture. We show further that each interaction contributes independently to CbtA-mediated toxicity and that disruption of both interactions is required to alleviate the observed toxicity. Although several other protein modulators are known to target FtsZ, the CbtA-interacting surface we identify represents a novel inhibitory target. Our findings establish CbtA as a dual function toxin that inhibits both cell division and cell elongation via direct and independent interactions with FtsZ and MreB.

  7. Interactions between cells and ionized dendritic biomaterials: Flow cytometry and fluorescence spectroscopic studies

    Science.gov (United States)

    Kannan, R. M.; Kolhe, Parag; Khandare, Jayant; Kannan, Sujatha; Lieh-Lai, Mary

    2004-03-01

    Dendrimers and hyperbranched polymers are a new class of macromolecules characterized by large density of "tunable" peripheral functional groups. Therefore dendrimers can serve as a model macromolecular system to study the influence of molecular geometry and charge density on transport across biological barriers, especially cellular interfaces. The effect of size, end-functionality, surface charge (pH), and the nature of the cell surface are expected to play an important role in transport, and are investigated using flow cytometry, fluorescene microscopy and UV/Vis spectroscopy. Our results suggest that at physiological pH, cationic polyamidoamine (PAMAM) dendrimers can enter the A549 cancer lung epithelial cells within 5 minutes, perhaps due to the favorable interaction between anionic surface receptors of cells and cationic PAMAM dendrimer, through adsorptive endocytosis. On the other hand, hyperbranched polyol, which is a neutral polymer at physiological pH, enters cells at a much slower rate. The entry of hyperbranched polyol may be because of fluid-phase pinocytosis. Our results also indicate that the dendritic polymers enter the cell surface much more rapidly than linear polymers, and some small drugs, suggesting that the high density of functional groups plays a key role in the interaction with the cell surface, and the subsequent transport inside.

  8. Characterization of the aspects of osteoprogenitor cell interactions with physical tetracalcium phosphate anchorage on titanium implant surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Chia-Ling [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, Feng Chia University, Taichung 40724, Taiwan (China); Dental Medical Devices and Materials Research Center, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Chang, Ya-Yuan; Liou, Cian-Hua [Alliance Global Technology Co., Ltd., Kaohsiung Medical Device Special Zone in Southern Taiwan Science Park, Kaohsiung 82151, Taiwan (China); Chen, Wen-Cheng, E-mail: wencchen@fcu.edu.tw [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, Feng Chia University, Taichung 40724, Taiwan (China)

    2015-04-01

    Well-designed implants are used not only to modify the geometry of the implant but also to change the chemical properties of its surfaces. The present study aims to assess the biofunctional effects of tetracalcium phosphate (TTCP) particles as a physical anchor on the implant surface derived through sandblasting. The characteristics of the surface, cell viability, and alkaline phosphatase (ALP) activity toward osteoprogenitor cells (D1) were obtained. D1 cells were cultured on a plain surface that underwent sandblasting and acid etching (SLA) (control SLA group) and on different SLA surfaces with different anchoring TTCP rates (new test groups, M and H). The mean anchoring rates were 57% (M) and 74% (H), and the anchored thickness was estimated to range from 12.6 μm to 18.3 μm. Compared with the control SLA surface on Ti substrate, the new test groups with different TTCP anchoring rates (M and H) failed to improve cell proliferation significantly but had a well-differentiated D1 cell phenotype that enhanced ALP expression in the early stage of cell cultures, specifically, at day 7. Results suggest that the SLA surface with anchored TTCP can accelerate progenitor bone cell mineralization. This study shows the potential clinical application of the constructed geometry in TTCP anchorage on Ti for dental implant surface modification. - Highlights: • TTCP (tetracalcium phosphate) as a physical anchorage on implant is characterized. • Theoretical values of anchored thickness and capping areas were estimated. • TTCP anchored by sandblasting can accelerate progenitor bone cell mineralization. • TTCP anchored on SLA (sandblasting and acid etching) surface is a promising method.

  9. Characterization of the aspects of osteoprogenitor cell interactions with physical tetracalcium phosphate anchorage on titanium implant surfaces

    International Nuclear Information System (INIS)

    Ko, Chia-Ling; Chang, Ya-Yuan; Liou, Cian-Hua; Chen, Wen-Cheng

    2015-01-01

    Well-designed implants are used not only to modify the geometry of the implant but also to change the chemical properties of its surfaces. The present study aims to assess the biofunctional effects of tetracalcium phosphate (TTCP) particles as a physical anchor on the implant surface derived through sandblasting. The characteristics of the surface, cell viability, and alkaline phosphatase (ALP) activity toward osteoprogenitor cells (D1) were obtained. D1 cells were cultured on a plain surface that underwent sandblasting and acid etching (SLA) (control SLA group) and on different SLA surfaces with different anchoring TTCP rates (new test groups, M and H). The mean anchoring rates were 57% (M) and 74% (H), and the anchored thickness was estimated to range from 12.6 μm to 18.3 μm. Compared with the control SLA surface on Ti substrate, the new test groups with different TTCP anchoring rates (M and H) failed to improve cell proliferation significantly but had a well-differentiated D1 cell phenotype that enhanced ALP expression in the early stage of cell cultures, specifically, at day 7. Results suggest that the SLA surface with anchored TTCP can accelerate progenitor bone cell mineralization. This study shows the potential clinical application of the constructed geometry in TTCP anchorage on Ti for dental implant surface modification. - Highlights: • TTCP (tetracalcium phosphate) as a physical anchorage on implant is characterized. • Theoretical values of anchored thickness and capping areas were estimated. • TTCP anchored by sandblasting can accelerate progenitor bone cell mineralization. • TTCP anchored on SLA (sandblasting and acid etching) surface is a promising method

  10. The interaction of bacterial magnetosomes and human liver cancer cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Pingping, E-mail: wangpp@mail.iee.ac.cn [Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Chuanfang [Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Changyou [Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Yue; Pan, Weidong; Song, Tao [Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-04-01

    As the biogenic magnetic nanomaterial, bacterial magnetic nanoparticles, namely magnetosomes, provide many advantages for potential biomedical applications. As such, interactions among magnetosomes and target cells should be elucidated to develop their bioapplications and evaluate their biocompatibilities. In this study, the interaction of magnetosomes and human liver cancer HepG2 cells was examined. Prussian blue staining revealed numerous stained particles in or on the cells. Intracellular iron concentrations, measured through inductively coupled plasma optical emission spectroscopy, increased with the increasing concentration of the magnetosomes. Transmission electron microscopy images showed that magnetosomes could be internalized in cells, mainly encapsulated in membrane vesicles, such as endosomes and lysosomes, and partly found as free particles in the cytosol. Some of the magnetosomes on cellular surfaces were encapsulated through cell membrane ruffling, which is the initiating process of endocytosis. Applying low temperature treatment and using specific endocytic inhibitors, we validated that macropinocytosis and clathrin-mediated endocytosis were involved in magnetosome uptake by HepG2 cells. Consequently, we revealed the interaction and intrinsic endocytic mechanisms of magnetosomes and HepG2 cells. This study provides a basis for the further research on bacterial magnetosome applications in liver diseases. - Highlights: • Bacterial magnetosomes interact with HepG2 cells in a dose-dependent manner. • Magnetosomes are wrapped by membrane ruffling on cell surface. • Internalized magnetosomes mainly localize in endosomes and lysosomes. • Macropinocytosis and CME are involved in the cellular uptake of magnetosomes.

  11. A cell surface chondroitin sulfate proteoglycan, immunologically related to CD44, is involved in type I collagen-mediated melanoma cell motility and invasion

    DEFF Research Database (Denmark)

    Faassen, A E; Schrager, J A; Klein, D J

    1992-01-01

    The metastatic spread of tumor cells occurs through a complex series of events, one of which involves the adhesion of tumor cells to extracellular matrix (ECM) components. Multiple interactions between cell surface receptors of an adherent tumor cell and the surrounding ECM contribute to cell...... collagen could also be inhibited by removing cell surface chondroitin sulfate with chondroitinase. In contrast, type I collagen-mediated melanoma cell adhesion and spreading were not affected by either beta-D-xyloside or chondroitinase treatments. These results suggest that mouse melanoma CSPG...... was shown to be mediated, at least in part, by chondroitin sulfate. Additionally we have determined that mouse melanoma CSPG is composed of a 110-kD core protein that is recognized by anti-CD44 antibodies on Western blots. Collectively, our data suggests that interactions between a cell surface CD44-related...

  12. Planetary Surface-Atmosphere Interactions

    Science.gov (United States)

    Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.

    2013-09-01

    Planetary bodies having an accessible solid surface and significant atmosphere, such as Earth, Mars, Venus, Titan, share common phenomenology. Specifically wind induced transport of surface materials, subsequent erosion, the generation and transport of solid aerosols which leads both to chemical and electrostatic interaction with the atmosphere. How these processes affect the evolution of the atmosphere and surface will be discussed in the context of general planetology and the latest laboratory studies will be presented.

  13. The role of c-Src in the invasion and metastasis of hepatocellular carcinoma cells induced by association of cell surface GRP78 with activated α2M

    International Nuclear Information System (INIS)

    Zhao, Song; Li, Hongdan; Wang, Qingjun; Su, Chang; Wang, Guan; Song, Huijuan; Zhao, Liang; Luan, Zhidong; Su, Rongjian

    2015-01-01

    Emerging data have suggested that cell surface GRP78 is a multifunctional receptor and has been linked to proliferative and antiapoptotic signaling cascades. Activated α 2− macroglobin (α 2 M*) is a natural circulating ligand of cell surface GRP78. Association of cell surface GRP78 with α 2 M* is involved in the regulation of cell proliferation, survival and apoptosis in human cancers. The invasion and metastasis of HCC cells were examined using transwell and wound healing assay; Cell surface expression of GRP78 was detected by in cell western assay. Translocation of GRP78 from cytosol to cell surface was observed by transfection of GRP78-EGFP plus TRIRC-WGA staining. The levels of Src, phosphor-Src, FAK, phospho-FAK, EGFR, phospho-EGFR, phospho-Cortactin, phospho-Paxillin were determined by western blot. Cell surface expression of GRP78 in HCC tissue samples was observed by immunofluorescence. The distribution of Paxillin and Cortactin in HCC cells was also observed by immunofluorescence. The interaction between GRP78 and Src were detected by far-western blot, co-immunoprecipitation and GST pulldown. GRP78 mRNA was detected by RT-PCR. In the current study, we showed that association of cell surface GRP78 with α 2 M* stimulated the invasion and metastasis of HCC. Cell surface GRP78 could interact directly with c-Src, promoted the phosphorylation of c-Src at Y416. Inhibition of the tyrosine kinase activity of c-Src with PP2 reverted the stimulatory effect caused by association of cell surface GRP78 with α 2 M*. Moreover, association of cell surface GRP78 with α 2 M* facilitates the interaction between EGFR and c-Src and consequently phosphorylated EGFR at Y1101 and Y845, promoting the invasion and metastasis of HCCs. However, inhibition of the tyrosine kinase of c-Src do not affect the interaction between EGFR and Src. c-Src plays a critical role in the invasion and metastasis of HCC induced by association of cell surface GRP78 with α 2 M*. Cell surface GRP

  14. Nanomaterials modulate stem cell differentiation: biological interaction and underlying mechanisms.

    Science.gov (United States)

    Wei, Min; Li, Song; Le, Weidong

    2017-10-25

    Stem cells are unspecialized cells that have the potential for self-renewal and differentiation into more specialized cell types. The chemical and physical properties of surrounding microenvironment contribute to the growth and differentiation of stem cells and consequently play crucial roles in the regulation of stem cells' fate. Nanomaterials hold great promise in biological and biomedical fields owing to their unique properties, such as controllable particle size, facile synthesis, large surface-to-volume ratio, tunable surface chemistry, and biocompatibility. Over the recent years, accumulating evidence has shown that nanomaterials can facilitate stem cell proliferation and differentiation, and great effort is undertaken to explore their possible modulating manners and mechanisms on stem cell differentiation. In present review, we summarize recent progress in the regulating potential of various nanomaterials on stem cell differentiation and discuss the possible cell uptake, biological interaction and underlying mechanisms.

  15. Immuno-biosensor for Detection of CD20-Positive Cells Using Surface Plasmon Resonance

    Science.gov (United States)

    Shanehbandi, Dariush; Majidi, Jafar; Kazemi, Tohid; Baradaran, Behzad; Aghebati-Maleki, Leili; Fathi, Farzaneh; Ezzati Nazhad Dolatabadi, Jafar

    2017-01-01

    Purpose: Surface plasmon resonance (SPR) sensing confers a real-time assessment of molecular interactions between biomolecules and their ligands. This approach is highly sensitive and reproducible and could be employed to confirm the successful binding of drugs to cell surface targets. The specific affinity of monoclonal antibodies (MAb) for their target antigens is being utilized for development of immuno-sensors and therapeutic agents. CD20 is a surface protein of B lymphocytes which has been widely employed for immuno-targeting of B-cell related disorders. In the present study, binding ability of an anti-CD20 MAb to surface antigens of intact target cells was investigated by SPR technique. Methods: Two distinct strategies were used for immobilization of the anti-CD20 MAb onto gold (Au) chips. MUA (11-mercaptoundecanoic acid) and Staphylococcus aureus protein A (SpA) were the two systems used for this purpose. A suspension of CD20-positive Raji cells was injected in the analyte phase and the resulting interactions were analyzed and compared to those of MOLT-4 cell line as CD20-negative control. Results: Efficient binding of anti-CD20 MAb to the surface antigens of Raji cell line was confirmed by both immobilizing methods, whereas this MAb had not a noticeable affinity to the MOLT-4 cells. Conclusion: According to the outcomes, the investigated MAb had acceptable affinity and specificity to the target antigens on the cell surface and could be utilized for immuno-detection of CD20-positive intact cells by SPR method. PMID:28761820

  16. Surface strategies for control of neuronal cell adhesion: A review

    Science.gov (United States)

    Roach, P.; Parker, T.; Gadegaard, N.; Alexander, M. R.

    2010-06-01

    Material engineering methods have been used for many years to develop biomedical devices for use within the body to augment, repair or replace damaged tissues ranging from contact lenses to heart valves. Here we review the findings gathered from the wide and varied surface analytical approaches applied to study the interaction between biology and man-made materials. The key material characteristics identified to be important for biological recognition are surface chemistry, topography and compliance. Model surfaces with controlled chemistry and topography have provided insight into biological response to various types of topographical features over a wide range of length scales from nano to micrometres, along with 3D matrices that have been used as scaffolds to support cells for tissue formation. The cellular response to surfaces with localised areas of patterned chemistry and to those presenting gradually changing chemistry are discussed. Where previous reviews have been structured around specific classes of surface modification, e.g. self-assembly, or have broadly examined the response of various cells to numerous surfaces, we aim in this article to focus in particular on the tissues involved in the nervous system whilst providing a broad overview of key issues from the field of cell and protein surface interactions with surfaces. The goal of repair and treatment of diseases related to the central and peripheral nervous systems rely on understanding the local interfacial environment and controlling responses at the cellular level. The role of the protein layer deposited from serum containing media onto man-made surfaces is discussed. We highlight the particular problems associated with the repair of the nervous system, and review how neuronal attachment and axon guidance can be accomplished using various surface cues when cultured with single and multiple cell types. We include a brief glossary of techniques discussed in the body of this article aimed at the

  17. Interactions of Model Cell Membranes with Nanoparticles

    Science.gov (United States)

    D'Angelo, S. M.; Camesano, T. A.; Nagarajan, R.

    2011-12-01

    The same properties that give nanoparticles their enhanced function, such as high surface area, small size, and better conductivity, can also alter the cytotoxicity of nanomaterials. Ultimately, many of these nanomaterials will be released into the environment, and can cause cytotoxic effects to environmental bacteria, aquatic organisms, and humans. Previous results from our laboratory suggest that nanoparticles can have a detrimental effect on cells, depending on nanoparticle size. It is our goal to characterize the properties of nanomaterials that can result in membrane destabilization. We tested the effects of nanoparticle size and chemical functionalization on nanoparticle-membrane interactions. Gold nanoparticles at 2, 5,10, and 80 nm were investigated, with a concentration of 1.1x1010 particles/mL. Model cell membranes were constructed of of L-α-phosphatidylcholine (egg PC), which has negatively charged lipid headgroups. A quartz crystal microbalance with dissipation (QCM-D) was used to measure frequency changes at different overtones, which were related to mass changes corresponding to nanoparticle interaction with the model membrane. In QCM-D, a lipid bilayer is constructed on a silicon dioxide crystal. The crystals, oscillate at different harmonic frequencies depending upon changes in mass or energy dissipation. When mass is added to the crystal surface, such as through addition of a lipid vesicle solution, the frequency change decreases. By monitoring the frequency and dissipation, we could verify that a supported lipid bilayer (SLB) formed on the silica surface. After formation of the SLB, the nanoparticles can be added to the system, and the changes in frequency and dissipation are monitored in order to build a mechanistic understanding of nanoparticle-cell membrane interactions. For all of the smaller nanoparticles (2, 5, and 10 nm), nanoparticle addition caused a loss of mass from the lipid bilayer, which appears to be due to the formation of holes

  18. Collaboration Meets Interactive Surfaces (CMIS)

    DEFF Research Database (Denmark)

    Anslow, Craig; Campos, Pedro; Grisoni, Laurent

    2015-01-01

    This workshop proposes to bring together researchers who are interested in improving collaborative experiences through the combination of multiple interaction surfaces with diverse sizes and formats, ranging from large-scale walls, to tables, mobiles, and wearables. The opportunities for innovation...... exist, but the ITS, CHI, CSCW, and other HCI communities have not yet thoroughly addressed the problem of bringing effective collaboration activities together using multiple interactive surfaces, especially in complex work domains. Of particular interest is the potential synergy that one can obtain...

  19. Regulating DNA Self-assembly by DNA-Surface Interactions.

    Science.gov (United States)

    Liu, Longfei; Li, Yulin; Wang, Yong; Zheng, Jianwei; Mao, Chengde

    2017-12-14

    DNA self-assembly provides a powerful approach for preparation of nanostructures. It is often studied in bulk solution and involves only DNA-DNA interactions. When confined to surfaces, DNA-surface interactions become an additional, important factor to DNA self-assembly. However, the way in which DNA-surface interactions influence DNA self-assembly is not well studied. In this study, we showed that weak DNA-DNA interactions could be stabilized by DNA-surface interactions to allow large DNA nanostructures to form. In addition, the assembly can be conducted isothermally at room temperature in as little as 5 seconds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Extractable Bacterial Surface Proteins in Probiotic–Host Interaction

    Directory of Open Access Journals (Sweden)

    Fillipe L. R. do Carmo

    2018-04-01

    Full Text Available Some Gram-positive bacteria, including probiotic ones, are covered with an external proteinaceous layer called a surface-layer. Described as a paracrystalline layer and formed by the self-assembly of a surface-layer-protein (Slp, this optional structure is peculiar. The surface layer per se is conserved and encountered in many prokaryotes. However, the sequence of the corresponding Slp protein is highly variable among bacterial species, or even among strains of the same species. Other proteins, including surface layer associated proteins (SLAPs, and other non-covalently surface-bound proteins may also be extracted with this surface structure. They can be involved a various functions. In probiotic Gram-positives, they were shown by different authors and experimental approaches to play a role in key interactions with the host. Depending on the species, and sometime on the strain, they can be involved in stress tolerance, in survival within the host digestive tract, in adhesion to host cells or mucus, or in the modulation of intestinal inflammation. Future trends include the valorization of their properties in the formation of nanoparticles, coating and encapsulation, and in the development of new vaccines.

  1. Interaction of human endothelial cells and nickel-titanium materials modified with silicon ions

    Energy Technology Data Exchange (ETDEWEB)

    Lotkov, Aleksandr I., E-mail: lotkov@ispms.tsc.ru; Kashin, Oleg A., E-mail: okashin@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Kudryavtseva, Yuliya A., E-mail: yulia-k1970@mail.ru; Antonova, Larisa V., E-mail: antonova.la@mail.ru; Matveeva, Vera G., E-mail: matveeva-vg@mail.ru; Sergeeva, Evgeniya A., E-mail: sergeewa.ew@yandex.ru [Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, 650002 (Russian Federation); Kudryashov, Andrey N., E-mail: kudryashov@angioline.ru [Angioline Interventional Device Ltd, Novosibirsk, 630090 (Russian Federation)

    2015-10-27

    The paper studies the influence of chemical and phase compositions of NiTi surface layers modified with Si ions by plasma immersion implantation on their interaction with endothelial cells. It is shown that certain technological modes of Si ion implantation enhance the adhesion, proliferation, and viability of endothelial cells. It is found that the Si-modified NiTi surface is capable of stimulating the formation of capillary-like structures in the cell culture.

  2. Glycoprotein on cell surfaces

    International Nuclear Information System (INIS)

    Muramatsu, T.

    1975-01-01

    There are conjugated polysaccharides in cell membranes and outside of animal cells, and they play important role in the control of cell behavior. In this paper, the studies on the glycoprotein on cell surfaces are reported. It was found that the glycoprotein on cell surfaces have both N-glycoside type and O-glycoside type saccharic chains. Therefore it can be concluded that the basic structure of the saccharic chains in the glycoprotein on cell surfaces is similar to that of blood serum and body fluid. The main glycoprotein in the membranes of red blood corpuscles has been studied most in detail, and it also has both types of saccharic chains. The glycoprotein in liver cell membranes was found to have only the saccharic chains of acid type and to be in different pattern from that in endoplasmic reticula and nuclear membranes, which also has the saccharic chains of neutral type. The structure of the saccharic chains of H-2 antigen, i.e. the peculiar glycoprotein on the surfaces of lymph system cells, has been studied, and it is similar to the saccharic chains of glycoprotein in blood serum. The saccharic chain structures of H-2 antigen and TL antigen are different. TL, H-2 (D), Lna and H-2 (K) are the glycoprotein on cell surfaces, and are independent molecules. The analysis of the saccharic chain patterns on cell surfaces was carried out, and it was shown that the acid type saccharic chains were similar to those of ordinary glycoprotein, because the enzyme of pneumococci hydrolyzed most of the acid type saccharic chains. The change of the saccharic chain patterns of glycoprotein on cell surfaces owing to canceration and multiplication is complex matter. (Kako, I.)

  3. Surface grafting of carboxylic groups onto thermoplastic polyurethanes to reduce cell adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Alves, P., E-mail: palves@eq.uc.pt [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Ferreira, P. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Kaiser, Jean-Pierre [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Salk, Natalie [Mikrofertigung – Micro Engineering, Fraunhofer IFAM, Wiener Strasse 12, D-288359 Bremen (Germany); Bruinink, Arie [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Sousa, Hermínio C. de; Gil, M.H. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal)

    2013-10-15

    The interaction of polymers with other materials is an important issue, being their surface properties clearly crucial. For some important polymer applications, their surfaces have to be modified. Surface modification aims to tailor the surface characteristics of a material for a specific application without affecting its bulk properties. Materials can be surface modified by using biological, chemical or physical methods. The aim of this work was to improve the reactivity of the thermoplastic polyurethane (TPU) material (Elastollan{sup ®}) surface and to make its surface cell repellent by grafting carboxylic groups onto its surface. Two TPU materials were studied: a polyether-based TPU and a polyester-based TPU. The grafting efficiency was evaluated by contact angle measurements and by analytical determination of the COOH groups. Scanning electron microscopy (SEM) of the membranes surface was performed as well as cell adhesion tests. It was proved that the surfaces of the TPUs membranes were successfully modified and that cell adhesion was remarkably reduced.

  4. Cell surface binding and uptake of arginine- and lysine-rich penetratin peptides in absence and presence of proteoglycans

    KAUST Repository

    Åmand, Helene L.

    2012-11-01

    Cell surface proteoglycans (PGs) appear to promote uptake of arginine-rich cell-penetrating peptides (CPPs), but their exact functions are unclear. To address if there is specificity in the interactions of arginines and PGs leading to improved internalization, we used flow cytometry to examine uptake in relation to cell surface binding for penetratin and two arginine/lysine substituted variants (PenArg and PenLys) in wildtype CHO-K1 and PG-deficient A745 cells. All peptides were more efficiently internalized into CHO-K1 than into A745, but their cell surface binding was independent of cell type. Thus, PGs promote internalization of cationic peptides, irrespective of the chemical nature of their positive charges. Uptake of each peptide was linearly dependent on its cell surface binding, and affinity is thus important for efficiency. However, the gradients of these linear dependencies varied significantly. Thus each peptide\\'s ability to stimulate uptake once bound to the cell surface is reliant on formation of specific uptake-promoting interactions. Heparin affinity chromatography and clustering experiments showed that penetratin and PenArg binding to sulfated sugars is stabilized by hydrophobic interactions and result in clustering, whereas PenLys only interacts through electrostatic attraction. This may have implications for the molecular mechanisms behind arginine-specific uptake stimulation as penetratin and PenArg are more efficiently internalized than PenLys upon interaction with PGs. However, PenArg is also least affected by removal of PGs. This indicates that an increased arginine content not only improve PG-dependent uptake but also that PenArg is more adaptable as it can use several portals of entry into the cell. © 2012 Elsevier B.V.

  5. N-sulfation of heparan sulfate is critical for syndecan-4-mediated podocyte cell-matrix interactions

    NARCIS (Netherlands)

    Sugar, T.; Wassenhove-McCarthy, D.J.; Orr, A.W.; Green, J.; Kuppevelt, T.H. van; McCarthy, K.J.

    2016-01-01

    Previous research has shown that podocytes unable to assemble heparan sulfate on cell surface proteoglycan core proteins have compromised cell-matrix interactions. This report further explores the role of N-sulfation of intact heparan chains in podocyte-matrix interactions. For the purposes of this

  6. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    Science.gov (United States)

    Sandoval Amador, A.; Carreño Garcia, H.; Escobar Rivero, P.; Peña Ballesteros, D. Y.; Estupiñán Duran, H. A.

    2016-02-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti6Al4V surfaces were evaluated. Ti6Al4V surfaces were textured using a CO2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment.

  7. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    International Nuclear Information System (INIS)

    Sandoval Amador, A; Carreño Garcia, H; Escobar Rivero, P; Peña Ballesteros, D Y; Estupiñán Duran, H A

    2016-01-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti 6 Al 4 V surfaces were evaluated. Ti 6 Al 4 V surfaces were textured using a CO 2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment. (paper)

  8. Nucleic acid interactions with pyrite surfaces

    International Nuclear Information System (INIS)

    Mateo-Marti, E.; Briones, C.; Rogero, C.; Gomez-Navarro, C.; Methivier, Ch.; Pradier, C.M.; Martin-Gago, J.A.

    2008-01-01

    The study of the interaction of nucleic acid molecules with mineral surfaces is a field of growing interest in organic chemistry, origin of life, material science and biotechnology. We have characterized the adsorption of single-stranded peptide nucleic acid (ssPNA) on a natural pyrite surface, as well as the further adsorption of ssDNA on a PNA-modified pyrite surface. The characterization has been performed by means of reflection absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM) and X-ray photoemission spectroscopy (XPS) techniques. The N(1s) and S(2p) XPS core level peaks of PNA and PNA + DNA have been decomposed in curve-components that we have assigned to different chemical species. RAIRS spectra recorded for different concentrations show the presence of positive and negative adsorption bands, related to the semiconducting nature of the surface. The combination of the information gathered by these techniques confirms that PNA adsorbs on pyrite surface, interacting through nitrogen-containing groups of the nucleobases and the iron atoms of the surface, instead of the thiol group of the molecule. The strong PNA/pyrite interaction inhibits further hybridization of PNA with complementary ssDNA, contrary to the behavior reported on gold surfaces

  9. Nucleic acid interactions with pyrite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mateo-Marti, E. [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850-Torrejon de Ardoz, Madrid (Spain)], E-mail: mateome@inta.es; Briones, C.; Rogero, C. [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850-Torrejon de Ardoz, Madrid (Spain); Gomez-Navarro, C. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049-Madrid (Spain); Methivier, Ch.; Pradier, C.M. [Laboratoire de Reactivite de Surface, UMR CNRS 7609. Universite Pierre et Marie Curie, 4, Pl Jussieu, 75005-Paris (France); Martin-Gago, J.A. [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850-Torrejon de Ardoz, Madrid (Spain); Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049-Madrid (Spain)

    2008-09-03

    The study of the interaction of nucleic acid molecules with mineral surfaces is a field of growing interest in organic chemistry, origin of life, material science and biotechnology. We have characterized the adsorption of single-stranded peptide nucleic acid (ssPNA) on a natural pyrite surface, as well as the further adsorption of ssDNA on a PNA-modified pyrite surface. The characterization has been performed by means of reflection absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM) and X-ray photoemission spectroscopy (XPS) techniques. The N(1s) and S(2p) XPS core level peaks of PNA and PNA + DNA have been decomposed in curve-components that we have assigned to different chemical species. RAIRS spectra recorded for different concentrations show the presence of positive and negative adsorption bands, related to the semiconducting nature of the surface. The combination of the information gathered by these techniques confirms that PNA adsorbs on pyrite surface, interacting through nitrogen-containing groups of the nucleobases and the iron atoms of the surface, instead of the thiol group of the molecule. The strong PNA/pyrite interaction inhibits further hybridization of PNA with complementary ssDNA, contrary to the behavior reported on gold surfaces.

  10. The hydroxyflavone, fisetin, suppresses mast cell activation induced by interaction with activated T cell membranes

    Science.gov (United States)

    Nagai, K; Takahashi, Y; Mikami, I; Fukusima, T; Oike, H; Kobori, M

    2009-01-01

    Background and purpose: Cell-to-cell interactions between mast cells and activated T cells are increasingly recognized as a possible mechanism in the aetiology of allergic or non-allergic inflammatory disorders. To determine the anti-allergic effect of fisetin, we examined the ability of fisetin to suppress activation of the human mast cell line, HMC-1, induced by activated Jurkat T cell membranes. Experimental approach: HMC-1 cells were incubated with or without fisetin for 15 min and then co-cultured with Jurkat T cell membranes activated by phorbol-12-myristate 13-acetate for 16 h. We determined gene expression in activated HMC-1 cells by DNA microarray and quantitative reverse transcription (RT)-PCR analysis. We also examined activation of the transcription factor NF-κB and MAP kinases (MAPKs) in activated HMC-1 cells. Key results: Fisetin suppresses cell spreading and gene expression in HMC-1 cells stimulated by activated T cell membranes. Additionally, we show that these stimulated HMC-1 cells expressed granzyme B. The stimulatory interaction also induced activation of NF-κB and MAPKs; these activations were suppressed by fisetin. Fisetin also reduced the amount of cell surface antigen CD40 and intercellular adhesion molecule-1 (ICAM-1) on activated HMC-1 cells. Conclusions and implications: Fisetin suppressed activation of HMC-1 cells by activated T cell membranes by interfering with cell-to-cell interaction and inhibiting the activity of NF-κB and MAPKs and thereby suppressing gene expression. Fisetin may protect against the progression of inflammatory diseases by limiting interactions between mast cells and activated T cells. PMID:19702784

  11. Syndecans as cell surface receptors: Unique structure equates with functional diversity

    DEFF Research Database (Denmark)

    Choi, Youngsil; Chung, Heesung; Jung, Heyjung

    2011-01-01

    An increasing number of functions for syndecan cell surface heparan sulfate proteoglycans have been proposed over the last decade. Moreover, aberrant syndecan regulation has been found to play a critical role in multiple pathologies, including cancers, as well as wound healing and inflammation....... As receptors, they have much in common with other molecules on the cell surface. Syndecans are type I transmembrane molecules with cytoplasmic domains that link to the actin cytoskeleton and can interact with a number of regulators. However, they are also highly complex by virtue of their external...... glycosaminoglycan chains, especially heparan sulfate. This heterodisperse polysaccharide has the potential to interact with many ligands from diverse protein families. Here, we relate the structural features of syndecans to some of their known functions....

  12. Is there a predictable relationship between surface physical-chemical properties and cell behaviour at the interface?

    Directory of Open Access Journals (Sweden)

    Vitte J.

    2004-06-01

    Full Text Available There is much interest in predicting and controlling the outcome of interaction between artificial surfaces and living cells. However, although there is an impressive amount of information on the behaviour of many cell populations deposited on a variety of surfaces, there is presently no available theory to explain or even summarize these data. Indeed, it is not even obvious that such a theory may exist. The aim of the present review is to emphasize the problems encountered when one attempts to build such a theory. Three sequential steps of cell surface interactions are considered: 1 protein adsorption is a preliminary step liable to involve irreversible interaction between the surface and several hundreds of molecular species occurring in blood or plasma. 2 the second step is the formation of adhesive bonds. Several theoretical frameworks were suggested to account for this step, including DLVO theory, physical chemistry of surfaces, and formation of specific ligandreceptor bonds. It is concluded that present evidence supports the latter approach, although this involves serious difficulties. 3 The last step is the triggering of a specific cell program such as apoptosis, proliferation, migration, differentiation or activation. Recent evidence suggests that in addition to the nature and amount of stimulated surface receptors, additional cues such as substratum mechanical or topographical properties may significantly affect cell behaviour.

  13. Nanostructured Surfaces to Target and Kill Circulating Tumor Cells While Repelling Leukocytes

    Directory of Open Access Journals (Sweden)

    Michael J. Mitchell

    2012-01-01

    Full Text Available Hematogenous metastasis, the process of cancer cell migration from a primary to distal location via the bloodstream, typically leads to a poor patient prognosis. Selectin proteins hold promise in delivering drug-containing nanocarriers to circulating tumor cells (CTCs in the bloodstream, due to their rapid, force-dependent binding kinetics. However, it is challenging to deliver such nanocarriers while avoiding toxic effects on healthy blood cells, as many possess ligands that adhesively interact with selectins. Herein, we describe a nanostructured surface to capture flowing cancer cells, while preventing human neutrophil adhesion. Microtube surfaces with immobilized halloysite nanotubes (HNTs and E-selectin functionalized liposomal doxorubicin (ES-PEG L-DXR significantly increased the number of breast adenocarcinoma MCF7 cells captured from flow, yet also significantly reduced the number of captured neutrophils. Neutrophils firmly adhered and projected pseudopods on surfaces coated only with liposomes, while neutrophils adherent to HNT-liposome surfaces maintained a round morphology. Perfusion of both MCF7 cells and neutrophils resulted in primarily cancer cell adhesion to the HNT-liposome surface, and induced significant cancer cell death. This work demonstrates that nanostructured surfaces consisting of HNTs and ES-PEG L-DXR can increase CTC recruitment for chemotherapeutic delivery, while also preventing healthy cell adhesion and uptake of therapeutic intended for CTCs.

  14. Quantification of the number of EP3 receptors on a living CHO cell surface by the AFM

    International Nuclear Information System (INIS)

    Kim, Hyonchol; Arakawa, Hideo; Hatae, Noriyuki; Sugimoto, Yukihiko; Matsumoto, Osamu; Osada, Toshiya; Ichikawa, Atsushi; Ikai, Atsushi

    2006-01-01

    The distribution of EP3 receptors on a living cell surface was quantitatively studied by atomic force microscopy (AFM). Green fluorescent protein (GFP) was introduced to the extracellular region of the EP3 receptor on a CHO cell. A microbead was used as a probe to ensure certain contact area, whose surface was coated with anti-GFP antibody. The interactions between the antibodies and GFP molecules on the cell surface were recorded to observe the distribution of the receptors. The result indicated that EP3 receptors were distributed on the CHO cell surface not uniformly but in small patches coincident with immunohistochemical observation. Repeated measurements on the same area of cell surface gave confirmation that it was unlikely that the receptors were extracted from the cell membrane during the experiments. The measurement of single molecular interaction between GFP and the anti-GFP antibody was succeeded on the cell surface using compression-free force spectroscopy. The value of separation work required to break a single molecular pair was estimated to be about 1.5x10 -18 J. The number of EP3 receptor on the CHO cell surface was estimated using this value to be about 1x10 4 under the assumption that the area of the cell surface was about 5000 μm 2 . These results indicated that the number of receptors on a living cell surface could be quantified through the force measurement by the AFM

  15. Impact of 4 Lactobacillus plantarum capsular polysaccharide clusters on surface glycan composition and host cell signaling

    NARCIS (Netherlands)

    Remus, D.M.; Kranenburg, van R.; Swam, van I.I.; Taverne, N.; Bongers, R.S.; Wels, M.; Wells, J.; Bron, P.A.; Kleerebezem, M.

    2012-01-01

    Background - Bacterial cell surface-associated polysaccharides are involved in the interactions of bacteria with their environment and play an important role in the communication between pathogenic bacteria and their host organisms. Cell surface polysaccharides of probiotic species are far less well

  16. Using continuous porous silicon gradients to study the influence of surface topography on the behaviour of neuroblastoma cells

    International Nuclear Information System (INIS)

    Khung, Y.L.; Barritt, G.; Voelcker, N.H.

    2008-01-01

    The effects of surface topography on cell behaviour are the subject of intense research in cell biology. These effects have so far only been studied using substrate surfaces of discretely different topography. In this paper, we present a new approach to characterise cell growth on porous silicon gradients displaying pore sizes from several thousands to a few nanometers. This widely applicable format has the potential to significantly reduce sample numbers and hence analysis time and cost. Our gradient format was applied here to the culture of neuroblastoma cells in order to determine the effects of topography on cell growth parameters. Cell viability, morphology, length and area were characterised by fluorescence and scanning electron microscopy. We observed a dramatic influence of changes in surface topography on the density and morphology of adherent neuroblastoma cells. For example, pore size regimes where cell attachment is strongly discouraged were identified providing cues for the design of low-fouling surfaces. On pore size regimes more conducive to cell attachment, lateral cell-cell interactions crosslinked the cell layer to the substratum surface, while direct substrate-cell interactions were scarce. Finally, our study revealed that cells were sensitive to nanoscale surface topography with feature sizes of < 20 nm

  17. Microbe-surface interactions in biofouling and biocorrosion processes.

    Science.gov (United States)

    Beech, Iwona B; Sunner, Jan A; Hiraoka, Kenzo

    2005-09-01

    The presence of microorganisms on material surfaces can have a profound effect on materials performance. Surface-associated microbial growth, i.e. a biofilm, is known to instigate biofouling. The presence of biofilms may promote interfacial physico-chemical reactions that are not favored under abiotic conditions. In the case of metallic materials, undesirable changes in material properties due to a biofilm (or a biofouling layer) are referred to as biocorrosion or microbially influenced corrosion (MIC). Biofouling and biocorrosion occur in aquatic and terrestrial habitats varying in nutrient content, temperature, pressure and pH. Interfacial chemistry in such systems reflects a wide variety of physiological activities carried out by diverse microbial populations thriving within biofilms. Biocorrosion can be viewed as a consequence of coupled biological and abiotic electron-transfer reactions, i.e. redox reactions of metals, enabled by microbial ecology. Microbially produced extracellular polymeric substances (EPS), which comprise different macromolecules, mediate initial cell adhesion to the material surface and constitute a biofilm matrix. Despite their unquestionable importance in biofilm development, the extent to which EPS contribute to biocorrosion is not well-understood. This review offers a current perspective on material/microbe interactions pertinent to biocorrosion and biofouling, with EPS as a focal point, while emphasizing the role atomic force spectroscopy and mass spectrometry techniques can play in elucidating such interactions.

  18. Lunar dusty plasma: A result of interaction of the solar wind flux and ultraviolet radiation with the lunar surface

    International Nuclear Information System (INIS)

    Lisin, E A; Tarakanov, V P; Petrov, O F; Popel, S I

    2015-01-01

    One of the main problems of future missions to the Moon is associated with lunar dust. Solar wind flux and ultraviolet radiation interact with the lunar surface. As a result, there is a substantial surface change and a near-surface plasma sheath. Dust particles from the lunar regolith, which turned in this plasma because of any mechanical processes, can levitate above the surface, forming dust clouds. In preparing of the space experiments “Luna-Glob” and “Luna-Resource” particle-in-cell calculations of the near-surface plasma sheath parameters are carried out. Here we present some new results of particle-in-cell simulation of the plasma sheath formed near the surface of the moon as a result of interaction of the solar wind and ultraviolet radiation with the lunar surface. The conditions of charging and stable levitation of dust particles in plasma above the lunar surface are also considered. (paper)

  19. Using Force to Probe Single-Molecule Receptor-Cytoskeletal Anchoring Beneath the Surface of a Living Cell

    DEFF Research Database (Denmark)

    Evans, Evan; Kinoshita, Koji

    2007-01-01

    -cytoskeletal unbinding increased exponentially with the level of force, suggesting disruption at a site of single-molecule interaction. Since many important enzymes and signaling molecules are closely associated with a membrane receptor-cytoskeletal linkage, pulling on a receptor could alter interactions among its......The ligation of cell surface receptors often communicates a signal that initiates a cytoplasmic chemical cascade to implement an important cell function. Less well understood is how physical stress applied to a cell surface adhesive bond propagates throughout the cytostructure to catalyze...... or trigger important steps in these chemical processes. Probing the nanoscale impact of pulling on cell surface bonds, we discovered that receptors frequently detach prematurely from the interior cytostructure prior to failure of the exterior adhesive bond [Evans, E., Heinrich, V., Leung, A., and Kinoshita...

  20. Surface plasmon resonance sensing: from purified biomolecules to intact cells.

    Science.gov (United States)

    Su, Yu-Wen; Wang, Wei

    2018-04-12

    Surface plasmon resonance (SPR) has become a well-recognized label-free technique for measuring the binding kinetics between biomolecules since the invention of the first SPR-based immunosensor in 1980s. The most popular and traditional format for SPR analysis is to monitor the real-time optical signals when a solution containing ligand molecules is flowing over a sensor substrate functionalized with purified receptor molecules. In recent years, rapid development of several kinds of SPR imaging techniques have allowed for mapping the dynamic distribution of local mass density within single living cells with high spatial and temporal resolutions and reliable sensitivity. Such capability immediately enabled one to investigate the interaction between important biomolecules and intact cells in a label-free, quantitative, and single cell manner, leading to an exciting new trend of cell-based SPR bioanalysis. In this Trend Article, we first describe the principle and technical features of two types of SPR imaging techniques based on prism and objective, respectively. Then we survey the intact cell-based applications in both fundamental cell biology and drug discovery. We conclude the article with comments and perspectives on the future developments. Graphical abstract Recent developments in surface plasmon resonance (SPR) imaging techniques allow for label-free mapping the mass-distribution within single living cells, leading to great expansions in biomolecular interactions studies from homogeneous substrates functionalized with purified biomolecules to heterogeneous substrates containing individual living cells.

  1. Cell for studying electron-adsorbed gas interactions; Cellule d'etudes des interactions electron-gaz adsorbe

    Energy Technology Data Exchange (ETDEWEB)

    Golowacz, H; Degras, D A [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires, Deptartement de Physique des Plasmas et de la Fusion Controlee, Service de Physique Appliquee, Service de Physique des Interractions Electroniques, Section d' Etude des Interactions Gaz-Solides

    1967-07-01

    The geometry and the technology of a cell used for investigations on electron-adsorbed gas interactions are described. The resonance frequencies of the surface ions which are created by the electron impact on the adsorbed gas are predicted by simplified calculations. The experimental data relative to carbon monoxide and neon are in good agreement with these predictions. (authors) [French] Les caracteristiques geometriques et technologiques generales d'une cellule d'etude des interactions entre un faisceau d'electrons et un gaz adsorbe sont donnees. Un calcul simplifie permet de prevoir les frequences de resonance des ions de surface crees par l'impact des electrons sur le gaz adsorbe. Les donnees experimentales sur l'oxyde de carbone et le neon confirment les previsions du calcul. (auteurs)

  2. Potential effect of cationic liposomes on interactions with oral bacterial cells and biofilms.

    Science.gov (United States)

    Sugano, Marika; Morisaki, Hirobumi; Negishi, Yoichi; Endo-Takahashi, Yoko; Kuwata, Hirotaka; Miyazaki, Takashi; Yamamoto, Matsuo

    2016-01-01

    Although oral infectious diseases have been attributed to bacteria, drug treatments remain ineffective because bacteria and their products exist as biofilms. Cationic liposomes have been suggested to electrostatically interact with the negative charge on the bacterial surface, thereby improving the effects of conventional drug therapies. However, the electrostatic interaction between oral bacteria and cationic liposomes has not yet been examined in detail. The aim of the present study was to examine the behavior of cationic liposomes and Streptococcus mutans in planktonic cells and biofilms. Liposomes with or without cationic lipid were prepared using a reverse-phase evaporation method. The zeta potentials of conventional liposomes (without cationic lipid) and cationic liposomes were -13 and 8 mV, respectively, and both had a mean particle size of approximately 180 nm. We first assessed the interaction between liposomes and planktonic bacterial cells with a flow cytometer. We then used a surface plasmon resonance method to examine the binding of liposomes to biofilms. We confirmed the binding behavior of liposomes with biofilms using confocal laser scanning microscopy. The interactions between cationic liposomes and S. mutans cells and biofilms were stronger than those of conventional liposomes. Microscopic observations revealed that many cationic liposomes interacted with the bacterial mass and penetrated the deep layers of biofilms. In this study, we demonstrated that cationic liposomes had higher affinity not only to oral bacterial cells, but also biofilms than conventional liposomes. This electrostatic interaction may be useful as a potential drug delivery system to biofilms.

  3. Cluster structures influenced by interaction with a surface.

    Science.gov (United States)

    Witt, Christopher; Dieterich, Johannes M; Hartke, Bernd

    2018-05-30

    Clusters on surfaces are vitally important for nanotechnological applications. Clearly, cluster-surface interactions heavily influence the preferred cluster structures, compared to clusters in vacuum. Nevertheless, systematic explorations and an in-depth understanding of these interactions and how they determine the cluster structures are still lacking. Here we present an extension of our well-established non-deterministic global optimization package OGOLEM from isolated clusters to clusters on surfaces. Applying this approach to intentionally simple Lennard-Jones test systems, we produce a first systematic exploration that relates changes in cluster-surface interactions to resulting changes in adsorbed cluster structures.

  4. Isthmin targets cell-surface GRP78 and triggers apoptosis via induction of mitochondrial dysfunction.

    Science.gov (United States)

    Chen, M; Zhang, Y; Yu, V C; Chong, Y-S; Yoshioka, T; Ge, R

    2014-05-01

    Isthmin (ISM) is a secreted 60-kDa protein that potently induces endothelial cell (EC) apoptosis. It suppresses tumor growth and angiogenesis in mice when stably overexpressed in cancer cells. Although αvβ5 integrin serves as a low-affinity receptor for ISM, the mechanism by which ISM mediates antiangiogenesis and apoptosis in ECs remain to be fully resolved. In this work, we report the identification of cell-surface glucose-regulated protein 78 kDa (GRP78) as a high-affinity receptor for ISM (Kd=8.6 nM). We demonstrated that ISM-GRP78 interaction triggers apoptosis not only in activated ECs but also in cancer cells expressing high level of cell-surface GRP78. Normal cells and benign tumor cells tend to express low level of cell-surface GRP78 and are resistant to ISM-induced apoptosis. Upon binding to GRP78, ISM is internalized into ECs through clathrin-dependent endocytosis that is essential for its proapoptotic activity. Once inside the cell, ISM co-targets with GRP78 to mitochondria where it interacts with ADP/ATP carriers on the inner membrane and blocks ATP transport from mitochondria to cytosol, thereby causing apoptosis. Hence, ISM is a novel proapoptotic ligand that targets cell-surface GRP78 to trigger apoptosis by inducing mitochondrial dysfunction. The restricted and high-level expression of cell-surface GRP78 on cancer cells and cancer ECs make them uniquely susceptible to ISM-targeted apoptosis. Indeed, systemic delivery of recombinant ISM potently suppressed subcutaneous 4T1 breast carcinoma and B16 melanoma growth in mice by eliciting apoptosis selectively in the cancer cells and cancer ECs. Together, this work reveals a novel ISM-GRP78 apoptosis pathway and demonstrates the potential of ISM as a cancer-specific and dual-targeting anticancer agent.

  5. Isthmin targets cell-surface GRP78 and triggers apoptosis via induction of mitochondrial dysfunction

    Science.gov (United States)

    Chen, M; Zhang, Y; Yu, V C; Chong, Y-S; Yoshioka, T; Ge, R

    2014-01-01

    Isthmin (ISM) is a secreted 60-kDa protein that potently induces endothelial cell (EC) apoptosis. It suppresses tumor growth and angiogenesis in mice when stably overexpressed in cancer cells. Although αvβ5 integrin serves as a low-affinity receptor for ISM, the mechanism by which ISM mediates antiangiogenesis and apoptosis in ECs remain to be fully resolved. In this work, we report the identification of cell-surface glucose-regulated protein 78 kDa (GRP78) as a high-affinity receptor for ISM (Kd=8.6 nM). We demonstrated that ISM-GRP78 interaction triggers apoptosis not only in activated ECs but also in cancer cells expressing high level of cell-surface GRP78. Normal cells and benign tumor cells tend to express low level of cell-surface GRP78 and are resistant to ISM-induced apoptosis. Upon binding to GRP78, ISM is internalized into ECs through clathrin-dependent endocytosis that is essential for its proapoptotic activity. Once inside the cell, ISM co-targets with GRP78 to mitochondria where it interacts with ADP/ATP carriers on the inner membrane and blocks ATP transport from mitochondria to cytosol, thereby causing apoptosis. Hence, ISM is a novel proapoptotic ligand that targets cell-surface GRP78 to trigger apoptosis by inducing mitochondrial dysfunction. The restricted and high-level expression of cell-surface GRP78 on cancer cells and cancer ECs make them uniquely susceptible to ISM-targeted apoptosis. Indeed, systemic delivery of recombinant ISM potently suppressed subcutaneous 4T1 breast carcinoma and B16 melanoma growth in mice by eliciting apoptosis selectively in the cancer cells and cancer ECs. Together, this work reveals a novel ISM-GRP78 apoptosis pathway and demonstrates the potential of ISM as a cancer-specific and dual-targeting anticancer agent. PMID:24464222

  6. Plasma surface interaction processes and possible synergisms

    International Nuclear Information System (INIS)

    Behrisch, R.; Roberto, J.B.

    1984-08-01

    The process determining the plasma surface interaction in today's high temperature plasma experiments are investigated following several lines. First, in plasma devices, the particle and energy fluxes to the different first wall areas the fluxes from the walls back into the plasma are measured and the boundary plasma parameters are determined. The surface composition and structure of the walls, limiters and divertor plates are analyzed following exposure to many discharges. Secondly, the different surface processes which are expected to contribute to the plasma surface interaction (particularly to hydrogen particle balance and impurity introduction) are studied in simulation experiments using well defined particle beams

  7. High hydrostatic pressure inactivation of Lactobacillus plantarum cells in (O/W)-emulsions is independent from cell surface hydrophobicity and lipid phase parameters

    Science.gov (United States)

    Kafka, T. A.; Reitermayer, D.; Lenz, C. A.; Vogel, R. F.

    2017-07-01

    Inactivation efficiency of high hydrostatic pressure (HHP) processing of food is strongly affected by food matrix composition. We investigated effects of fat on HHP inactivation of spoilage-associated Lactobacillus (L.) plantarum strains using defined oil-in-water (O/W)-emulsion model systems. Since fat-mediated effects on HHP inactivation could be dependent on interactions between lipid phase and microbial cells, three major factors possibly influencing such interactions were considered, that is, cell surface hydrophobicity, presence and type of surfactants, and oil droplet size. Pressure tolerance varied noticeably among L. plantarum strains and was independent of cell surface hydrophobicity. We showed that HHP inactivation of all strains tended to be more effective in presence of fat. The observation in both, surfactant-stabilized and surfactant-free (O/W)-emulsion, indicates that cell surface hydrophobicity is no intrinsic pressure resistance factor. In contrast to the presence of fat per se, surfactant type and oil droplet size did not affect inactivation efficiency.

  8. Interaction of Cowpea Mosaic Virus (CPMV) Nanoparticles with Antigen Presenting Cells In Vitro and In Vivo

    Science.gov (United States)

    Rae, Chris S.; Manchester, Marianne

    2009-01-01

    Background Plant viruses such as Cowpea mosaic virus (CPMV) are increasingly being developed for applications in nanobiotechnology including vaccine development because of their potential for producing large quantities of antigenic material in plant hosts. In order to improve efficacy of viral nanoparticles in these types of roles, an investigation of the individual cell types that interact with the particles is critical. In particular, it is important to understand the interactions of a potential vaccine with antigen presenting cells (APCs) of the immune system. CPMV was previously shown to interact with vimentin displayed on cell surfaces to mediate cell entry, but the expression of surface vimentin on APCs has not been characterized. Methodology The binding and internalization of CPMV by several populations of APCs was investigated both in vitro and in vivo by flow cytometry and fluorescence confocal microscopy. The association of the particles with mouse gastrointestinal epithelium and Peyer's patches was also examined by confocal microscopy. The expression of surface vimentin on APCs was also measured. Conclusions We found that CPMV is bound and internalized by subsets of several populations of APCs both in vitro and in vivo following intravenous, intraperitoneal, and oral administration, and also by cells isolated from the Peyer's patch following gastrointestinal delivery. Surface vimentin was also expressed on APC populations that could internalize CPMV. These experiments demonstrate that APCs capture CPMV particles in vivo, and that further tuning the interaction with surface vimentin may facilitate increased uptake by APCs and priming of antibody responses. These studies also indicate that CPMV particles likely access the systemic circulation following oral delivery via the Peyer's patch. PMID:19956734

  9. ProFASTA: a pipeline web server for fungal protein scanning with integration of cell surface prediction software

    NARCIS (Netherlands)

    de Groot, P.W.J.; Brandt, B.W.

    2012-01-01

    Surface proteins, such as those located in the cell wall of fungi, play an important role in the interaction with the surrounding environment. For instance, they mediate primary host-pathogen interactions and are crucial to the establishment of biofilms and fungal infections. Surface localization of

  10. Facile method to stain the bacterial cell surface for super-resolution fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gunsolus, Ian L.; Hu, Dehong; Mihai, Cosmin; Lohse, Samuel E.; Lee, Chang-Soo; Torelli, Marco; Hamers, Robert J.; Murphy, Catherine; Orr, Galya; Haynes, Christy L.

    2014-01-01

    A method to fluorescently stain the surfaces of both Gram-negative and Gram-positive bacterial cells compatible with super-resolution fluorescence microscopy is presented. This method utilizes a commercially-available fluorescent probe to label primary amines at the surface of the cell. We demonstrate efficient staining of two bacterial strains, the Gram-negative Shewanella oneidensis MR-1 and the Gram-positive Bacillus subtilis 168. Using structured illumination microscopy and stochastic optical reconstruction microscopy, which require high quantum yield or specialized dyes, we show that this staining method may be used to resolve the bacterial cell surface with sub-diffraction-limited resolution. We further use this method to identify localization patterns of nanomaterials, specifically cadmium selenide quantum dots, following interaction with bacterial cells.

  11. A simplified model for dynamics of cell rolling and cell-surface adhesion

    International Nuclear Information System (INIS)

    Cimrák, Ivan

    2015-01-01

    We propose a three dimensional model for the adhesion and rolling of biological cells on surfaces. We study cells moving in shear flow above a wall to which they can adhere via specific receptor-ligand bonds based on receptors from selectin as well as integrin family. The computational fluid dynamics are governed by the lattice-Boltzmann method. The movement and the deformation of the cells is described by the immersed boundary method. Both methods are fully coupled by implementing a two-way fluid-structure interaction. The adhesion mechanism is modelled by adhesive bonds including stochastic rules for their creation and rupture. We explore a simplified model with dissociation rate independent of the length of the bonds. We demonstrate that this model is able to resemble the mesoscopic properties, such as velocity of rolling cells

  12. Direct observation of nanoparticle-cancer cell nucleus interactions.

    Science.gov (United States)

    Dam, Duncan Hieu M; Lee, Jung Heon; Sisco, Patrick N; Co, Dick T; Zhang, Ming; Wasielewski, Michael R; Odom, Teri W

    2012-04-24

    We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultrafast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy.

  13. Bimanual Interaction with Interscopic Multi-Touch Surfaces

    Science.gov (United States)

    Schöning, Johannes; Steinicke, Frank; Krüger, Antonio; Hinrichs, Klaus; Valkov, Dimitar

    Multi-touch interaction has received considerable attention in the last few years, in particular for natural two-dimensional (2D) interaction. However, many application areas deal with three-dimensional (3D) data and require intuitive 3D interaction techniques therefore. Indeed, virtual reality (VR) systems provide sophisticated 3D user interface, but then lack efficient 2D interaction, and are therefore rarely adopted by ordinary users or even by experts. Since multi-touch interfaces represent a good trade-off between intuitive, constrained interaction on a touch surface providing tangible feedback, and unrestricted natural interaction without any instrumentation, they have the potential to form the foundation of the next generation user interface for 2D as well as 3D interaction. In particular, stereoscopic display of 3D data provides an additional depth cue, but until now the challenges and limitations for multi-touch interaction in this context have not been considered. In this paper we present new multi-touch paradigms and interactions that combine both traditional 2D interaction and novel 3D interaction on a touch surface to form a new class of multi-touch systems, which we refer to as interscopic multi-touch surfaces (iMUTS). We discuss iMUTS-based user interfaces that support interaction with 2D content displayed in monoscopic mode and 3D content usually displayed stereoscopically. In order to underline the potential of the proposed iMUTS setup, we have developed and evaluated two example interaction metaphors for different domains. First, we present intuitive navigation techniques for virtual 3D city models, and then we describe a natural metaphor for deforming volumetric datasets in a medical context.

  14. T cell-B cell interactions in primary immunodeficiencies.

    Science.gov (United States)

    Tangye, Stuart G; Deenick, Elissa K; Palendira, Umaimainthan; Ma, Cindy S

    2012-02-01

    Regulated interactions between cells of the immune system facilitate the generation of successful immune responses, thereby enabling efficient neutralization and clearance of pathogens and the establishment of both cell- and humoral-mediated immunological memory. The corollary of this is that impediments to efficient cell-cell interactions, normally necessary for differentiation and effector functions of immune cells, underly the clinical features and disease pathogenesis of primary immunodeficiencies. In affected individuals, these defects manifest as impaired long-term humoral immunity and susceptibility to infection by specific pathogens. In this review, we discuss the importance of, and requirements for, effective interactions between B cells and T cells during the formation of CD4(+) T follicular helper cells and the elicitation of cytotoxic function of virus-specific CD8(+) T cells, as well as how these processes are abrogated in primary immunodeficiencies due to loss-of-function mutations in defined genes. © 2012 New York Academy of Sciences.

  15. Cellular interaction of a layer-by-layer based drug delivery system depending on material properties and cell types.

    Science.gov (United States)

    Brueckner, Mandy; Jankuhn, Steffen; Jülke, Eva-Maria; Reibetanz, Uta

    2018-01-01

    Drug delivery systems (DDS) and their interaction with cells are a controversial topic in the development of therapeutic concepts and approaches. On one hand, DDS are very useful for protected and targeted transport of defined dosages of active agents. On the other hand, their physicochemical properties such as material, size, shape, charge, or stiffness have a huge impact on cellular uptake and intracellular processing. Additionally, even identical DDS can undergo a completely diverse interaction with different cell types. However, quite often in in vitro DDS/cell interaction experiments, those aspects are not considered and DDS and cells are randomly chosen. Hence, our investigations provide an insight into layer-by-layer designed microcarriers with modifications of only some of the most important parameters (surface charge, stiffness, and applied microcarrier/cell ratio) and their influence on cellular uptake and viability. We also considered the interaction of these differently equipped DDS with several cell types and investigated professional phagocytes (neutrophil granulocytes; macrophages) as well as non-professional phagocytes (epithelial cells) under comparable conditions. We found that even small modifications such as layer-by-layer (LbL)-microcarriers with positive or negative surface charge, or LbL-microcarriers with solid core or as hollow capsules but equipped with the same surface properties, show significant differences in interaction and viability, and several cell types react very differently to the offered DDS. As a consequence, the properties of the DDS have to be carefully chosen with respect to the addressed cell type with the aim to efficiently transport a desired agent.

  16. Diffusion of MMPs on the surface of collagen fibrils: the mobile cell surface-collagen substratum interface.

    Directory of Open Access Journals (Sweden)

    Ivan E Collier

    Full Text Available Remodeling of the extracellular matrix catalyzed by MMPs is central to morphogenetic phenomena during development and wound healing as well as in numerous pathologic conditions such as fibrosis and cancer. We have previously demonstrated that secreted MMP-2 is tethered to the cell surface and activated by MT1-MMP/TIMP-2-dependent mechanism. The resulting cell-surface collagenolytic complex (MT1-MMP(2/TIMP-2/MMP-2 can initiate (MT1-MMP and complete (MMP-2 degradation of an underlying collagen fibril. The following question remained: What is the mechanism of substrate recognition involving the two structures of relatively restricted mobility, the cell surface enzymatic complex and a collagen fibril embedded in the ECM? Here we demonstrate that all the components of the complex are capable of processive movement on a surface of the collagen fibril. The mechanism of MT1-MMP movement is a biased diffusion with the bias component dependent on the proteolysis of its substrate, not adenosine triphosphate (ATP hydrolysis. It is similar to that of the MMP-1 Brownian ratchet we described earlier. In addition, both MMP-2 and MMP-9 as well as their respective complexes with TIMP-1 and -2 are capable of Brownian diffusion on the surface of native collagen fibrils without noticeable dissociation while the dimerization of MMP-9 renders the enzyme immobile. Most instructive is the finding that the inactivation of the enzymatic activity of MT1-MMP has a detectable negative effect on the cell force developed in miniaturized 3D tissue constructs. We propose that the collagenolytic complex (MT1-MMP(2/TIMP-2/MMP-2 represents a Mobile Cell Surface-Collagen Substratum Interface. The biological implications of MT1-MMP acting as a molecular ratchet tethered to the cell surface in complex with MMP-2 suggest a new mechanism for the role of spatially regulated peri-cellular proteolysis in cell-matrix interactions.

  17. Interacting boson model with surface delta interaction between nucleons: Structure and interaction of bosons

    International Nuclear Information System (INIS)

    Druce, C.H.; Moszkowski, S.A.

    1986-01-01

    The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. We have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson-proton-boson interaction for the case of degenerate orbits. A connection is made between these coefficients and the parameters of the interaction boson model Hamiltonian. A link between the latter parameters and the single boson energies is suggested

  18. Interacting boson model with surface delta interaction between nucleons: Structure and interaction of bosons

    Energy Technology Data Exchange (ETDEWEB)

    Druce, C.H.; Moszkowski, S.A.

    1986-01-01

    The surface delta interaction is used as an effective nucleon-nucleon interaction to investigate the structure and interaction of the bosons in the interacting boson model. We have obtained analytical expressions for the coefficients of a multipole expansion of the neutron-boson-proton-boson interaction for the case of degenerate orbits. A connection is made between these coefficients and the parameters of the interaction boson model Hamiltonian. A link between the latter parameters and the single boson energies is suggested.

  19. Stem cell autotomy and niche interaction in different systems.

    Science.gov (United States)

    Dorn, David C; Dorn, August

    2015-07-26

    The best known cases of cell autotomy are the formation of erythrocytes and thrombocytes (platelets) from progenitor cells that reside in special niches. Recently, autotomy of stem cells and its enigmatic interaction with the niche has been reported from male germline stem cells (GSCs) in several insect species. First described in lepidopterans, the silkmoth, followed by the gipsy moth and consecutively in hemipterans, foremost the milkweed bug. In both, moths and the milkweed bug, GSCs form finger-like projections toward the niche, the apical cells (homologs of the hub cells in Drosophila). Whereas in the milkweed bug the projection terminals remain at the surface of the niche cells, in the gipsy moth they protrude deeply into the singular niche cell. In both cases, the projections undergo serial retrograde fragmentation with progressing signs of autophagy. In the gipsy moth, the autotomized vesicles are phagocytized and digested by the niche cell. In the milkweed bug the autotomized vesicles accumulate at the niche surface and disintegrate. Autotomy and sprouting of new projections appears to occur continuously. The significance of the GSC-niche interactions, however, remains enigmatic. Our concept on the signaling relationship between stem cell-niche in general and GSC and niche (hub cells and cyst stem cells) in particular has been greatly shaped by Drosophila melanogaster. In comparing the interactions of GSCs with their niche in Drosophila with those in species exhibiting GSC autotomy it is obvious that additional or alternative modes of stem cell-niche communication exist. Thus, essential signaling pathways, including niche-stem cell adhesion (E-cadherin) and the direction of asymmetrical GSC division - as they were found in Drosophila - can hardly be translated into the systems where GSC autotomy was reported. It is shown here that the serial autotomy of GSC projections shows remarkable similarities with Wallerian axonal destruction, developmental axon

  20. Stem cell autotomy and niche interaction in different systems

    Science.gov (United States)

    Dorn, David C; Dorn, August

    2015-01-01

    The best known cases of cell autotomy are the formation of erythrocytes and thrombocytes (platelets) from progenitor cells that reside in special niches. Recently, autotomy of stem cells and its enigmatic interaction with the niche has been reported from male germline stem cells (GSCs) in several insect species. First described in lepidopterans, the silkmoth, followed by the gipsy moth and consecutively in hemipterans, foremost the milkweed bug. In both, moths and the milkweed bug, GSCs form finger-like projections toward the niche, the apical cells (homologs of the hub cells in Drosophila). Whereas in the milkweed bug the projection terminals remain at the surface of the niche cells, in the gipsy moth they protrude deeply into the singular niche cell. In both cases, the projections undergo serial retrograde fragmentation with progressing signs of autophagy. In the gipsy moth, the autotomized vesicles are phagocytized and digested by the niche cell. In the milkweed bug the autotomized vesicles accumulate at the niche surface and disintegrate. Autotomy and sprouting of new projections appears to occur continuously. The significance of the GSC-niche interactions, however, remains enigmatic. Our concept on the signaling relationship between stem cell-niche in general and GSC and niche (hub cells and cyst stem cells) in particular has been greatly shaped by Drosophila melanogaster. In comparing the interactions of GSCs with their niche in Drosophila with those in species exhibiting GSC autotomy it is obvious that additional or alternative modes of stem cell-niche communication exist. Thus, essential signaling pathways, including niche-stem cell adhesion (E-cadherin) and the direction of asymmetrical GSC division - as they were found in Drosophila - can hardly be translated into the systems where GSC autotomy was reported. It is shown here that the serial autotomy of GSC projections shows remarkable similarities with Wallerian axonal destruction, developmental axon

  1. Cells behaviors and genotoxicity on topological surface

    International Nuclear Information System (INIS)

    Yang, N.; Yang, M.K.; Bi, S.X.; Chen, L.; Zhu, Z.Y.; Gao, Y.T.; Du, Z.

    2013-01-01

    To investigate different cells behaviors and genotoxicity, which were driven by specific microenvironments, three patterned surfaces (pillars, wide grooves and narrow grooves) and one smooth surface were prepared by template-based technique. Vinculin is a membrane-cytoskeletal protein in focal adhesion plaques and associates with cell–cell and cell–matrix junctions, which can promote cell adhesion and spreading. The immunofluorescence staining of vinculin revealed that the narrow grooves patterned substrate was favorable for L929 cell adhesion. For cell multiplication, the narrow grooves surface was fitted for the proliferation of L929, L02 and MSC cells, the pillars surface was only in favor of L929 cells to proliferate during 7 days of cell cultivation. Cell genetic toxicity was evaluated by cellular micronuclei test (MNT). The results indicated that topological surfaces were more suitable for L929 cells to proliferate and maintain the stability of genome. On the contrary, the narrow grooves surface induced higher micronuclei ratio of L02 and MSC cells than other surfaces. With the comprehensive results of cell multiplication and MNT, it was concluded that the wide grooves surface was best fitted for L02 cells to proliferate and have less DNA damages, and the smooth surface was optimum for the research of MSC cells in vitro. - Highlights: • Different cells behaviors on microstructure surfaces were discussed in this paper. • The expression of cell protein of Vinculin was studied in this research. • Cellular micronuclei test was applied to evaluate cells' genotoxicity. • Cell genotoxicity was first studied in the research field of topological surfaces

  2. Time-Domain Modeling of RF Antennas and Plasma-Surface Interactions

    Directory of Open Access Journals (Sweden)

    Jenkins Thomas G.

    2017-01-01

    Full Text Available Recent advances in finite-difference time-domain (FDTD modeling techniques allow plasma-surface interactions such as sheath formation and sputtering to be modeled concurrently with the physics of antenna near- and far-field behavior and ICRF power flow. Although typical sheath length scales (micrometers are much smaller than the wavelengths of fast (tens of cm and slow (millimeter waves excited by the antenna, sheath behavior near plasma-facing antenna components can be represented by a sub-grid kinetic sheath boundary condition, from which RF-rectified sheath potential variation over the surface is computed as a function of current flow and local plasma parameters near the wall. These local time-varying sheath potentials can then be used, in tandem with particle-in-cell (PIC models of the edge plasma, to study sputtering effects. Particle strike energies at the wall can be computed more accurately, consistent with their passage through the known potential of the sheath, such that correspondingly increased accuracy of sputtering yields and heat/particle fluxes to antenna surfaces is obtained. The new simulation capabilities enable time-domain modeling of plasma-surface interactions and ICRF physics in realistic experimental configurations at unprecedented spatial resolution. We will present results/animations from high-performance (10k-100k core FDTD/PIC simulations of Alcator C-Mod antenna operation.

  3. The S-layer Associated Serine Protease Homolog PrtX Impacts Cell Surface-Mediated Microbe-Host Interactions of Lactobacillus acidophilus NCFM

    Directory of Open Access Journals (Sweden)

    Brant R. Johnson

    2017-06-01

    Full Text Available Health-promoting aspects attributed to probiotic microorganisms, including adhesion to intestinal epithelia and modulation of the host mucosal immune system, are mediated by proteins found on the bacterial cell surface. Notably, certain probiotic and commensal bacteria contain a surface (S- layer as the outermost stratum of the cell wall. S-layers are non-covalently bound semi-porous, crystalline arrays of self-assembling, proteinaceous subunits called S-layer proteins (SLPs. Recent evidence has shown that multiple proteins are non-covalently co-localized within the S-layer, designated S-layer associated proteins (SLAPs. In Lactobacillus acidophilus NCFM, SLP and SLAPs have been implicated in both mucosal immunomodulation and adhesion to the host intestinal epithelium. In this study, a S-layer associated serine protease homolog, PrtX (prtX, lba1578, was deleted from the chromosome of L. acidophilus NCFM. Compared to the parent strain, the PrtX-deficient strain (ΔprtX demonstrated increased autoaggregation, an altered cellular morphology, and pleiotropic increases in adhesion to mucin and fibronectin, in vitro. Furthermore, ΔprtX demonstrated increased in vitro immune stimulation of IL-6, IL-12, and IL-10 compared to wild-type, when exposed to mouse dendritic cells. Finally, in vivo colonization of germ-free mice with ΔprtX led to an increase in epithelial barrier integrity. The absence of PrtX within the exoproteome of a ΔprtX strain caused morphological changes, resulting in a pleiotropic increase of the organisms’ immunomodulatory properties and interactions with some intestinal epithelial cell components.

  4. Plasma-surface interactions under high heat and particle fluxes

    NARCIS (Netherlands)

    De Temmerman, G.; Bystrov, K.; Liu, F.; Liu, W.; Morgan, T.; Tanyeli, I.; van den Berg, M.; Xu, H.; Zielinski, J.

    2013-01-01

    The plasma-surface interactions expected in the divertor of a future fusion reactor are characterized by extreme heat and particle fluxes interacting with the plasma-facing surfaces. Powerful linear plasma generators are used to reproduce the expected plasma conditions and allow plasma-surface

  5. Cell shape and spreading of stromal (mesenchymal) stem cells cultured on fibronectin coated gold and hydroxyapatite surfaces

    DEFF Research Database (Denmark)

    Dolatshahi-Pirouz, A; Jensen, Thomas Hartvig Lindkjær; Kolind, Kristian

    2011-01-01

    In order to identify the cellular mechanisms leading to the biocompatibility of hydroxyapatite implants, we studied the interaction of human bone marrow derived stromal (mesenchymal) stem cells (hMSCs) with fibronectin-coated gold (Au) and hydroxyapatite (HA) surfaces. The adsorption of fibronectin...

  6. Human mammary progenitor cell fate decisions are products of interactions with combinatorial microenvironments

    Energy Technology Data Exchange (ETDEWEB)

    LaBarge, Mark A; Nelson, Celeste M; Villadsen, Rene; Fridriksdottir, Agla; Ruth, Jason R; Stampfer, Martha R; Petersen, Ole W; Bissell, Mina J

    2008-09-19

    In adult tissues, multi-potent progenitor cells are some of the most primitive members of the developmental hierarchies that maintain homeostasis. That progenitors and their more mature progeny share identical genomes, suggests that fate decisions are directed by interactions with extrinsic soluble factors, ECM, and other cells, as well as physical properties of the ECM. To understand regulation of fate decisions, therefore, would require a means of understanding carefully choreographed combinatorial interactions. Here we used microenvironment protein microarrays to functionally identify combinations of cell-extrinsic mammary gland proteins and ECM molecules that imposed specific cell fates on bipotent human mammary progenitor cells. Micropatterned cell culture surfaces were fabricated to distinguish between the instructive effects of cell-cell versus cell-ECM interactions, as well as constellations of signaling molecules; and these were used in conjunction with physiologically relevant 3 dimensional human breast cultures. Both immortalized and primary human breast progenitors were analyzed. We report on the functional ability of those proteins of the mammary gland that maintain quiescence, maintain the progenitor state, and guide progenitor differentiation towards myoepithelial and luminal lineages.

  7. Spatio-temporal Characterization of Ligand-Receptor Interactions in Blood Stem-Cell Rolling

    KAUST Repository

    Al Alwan, Bader

    2017-08-16

    One of the most important issues in the research on hematopoietic stem/progenitor cells (HSPCs) is to understand the mechanism of the homing process of these cells to the bone marrow after being transplanted into patients and establish the production of various blood cell types. The HSPCs first come in contact with the endothelial cells. This contact is known as adhesion and occurs through a multi-step paradigm ending with transmigration to the bone marrow niche. The initial step of the homing, tethering and rolling of HSPCs is mediated by P- and E-Selectins expressed on the endothelial cell surface through their interactions with the ligands expressed by HSPCs. Here we developed a novel experimental method to unravel the molecular mechanisms of the selectin-ligands interactions in vitro at the single molecule level by combining microfluidics and single-molecule fluorescence imaging. Our method enables direct visualization of the nanoscale spatiotemporal dynamics of the E-selectin-ligand (PSGL-1) interactions under conditions of shear stress acting on the cells at the molecular level in real time.

  8. Glycosaminoglycans mediate retention of the poxvirus type I interferon binding protein at the cell surface to locally block interferon antiviral responses

    Science.gov (United States)

    Montanuy, Imma; Alejo, Ali; Alcami, Antonio

    2011-01-01

    Eradication of smallpox was accomplished 30 yr ago, but poxviral infections still represent a public health concern due to the potential release of variola virus or the emergence of zoonotic poxviruses, such as monkeypox virus. A critical determinant of poxvirus virulence is the inhibition of interferons (IFNs) by the virus-encoded type I IFN-binding protein (IFNα/βBP). This immunomodulatory protein is secreted and has the unique property of interacting with the cell surface in order to prevent IFN-mediated antiviral responses. However, the mechanism of its attachment to the cell surface remains unknown. Using surface plasmon resonance and cell-binding assays, we report that the IFNα/βBP from vaccinia virus, the smallpox vaccine, interacts with cell surface glycosaminoglycans (GAGs). Analysis of the contribution of different regions of the protein to cell surface binding demonstrated that clusters of basic residues in the first immunoglobulin domain mediate GAG interactions. Furthermore, mutation of the GAG-interaction motifs does not affect its IFN-binding and -blocking capacity. Functional conservation of GAG-binding sites is demonstrated for the IFNα/βBP from variola and monkeypox viruses, extending our understanding of immune modulation by the most virulent human poxviruses. These results are relevant for the design of improved vaccines and intervention strategies.—Montanuy, I., Alejo, A., Alcami, A. Glycosaminoglycans mediate retention of the poxvirus type I interferon binding protein at the cell surface to locally block interferon antiviral responses. PMID:21372110

  9. A model system for carbohydrates interactions on single-crystalline Ru surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thanh Nam

    2015-07-01

    In this thesis, I present a model system for carbohydrate interactions with single-crystalline Ru surfaces. Geometric and electronic properties of copper phthalocyanine (CuPc) on top of graphene on hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10) surfaces have been studied. First, the Fermi surfaces and band structures of the three Ru surfaces were investigated by high-resolution angle-resolved photoemission spectroscopy. The experimental data and theoretical calculations allow to derive detailed information about the momentum-resolved electronic structure. The results can be used as a reference to understand the chemical and catalytic properties of Ru surfaces. Second, graphene layers were prepared on the three different Ru surfaces. Using low-energy electron diffraction and scanning tunneling microscopy, it was found that graphene can be grown in well-ordered structures on all three surfaces, hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10), although they have different surface symmetries. Evidence for a strong interaction between graphene and Ru surfaces is a 1.3-1.7 eV increase in the graphene π-bands binding energy with respect to free-standing graphene sheets. This energy variation is due to the hybridization between the graphene pi bands and the Ru 4d electrons, while the lattice mismatch does not play an important role in the bonding between graphene and Ru surfaces. Finally, the geometric and electronic structures of CuPc on Ru(10 anti 10), graphene/Ru(10 anti 10), and graphene/Ru(0001) have been studied in detail. CuPc molecules can be grown well-ordered on Ru(10 anti 10) but not on Ru(0001). The growth of CuPc on graphene/Ru(10 anti 10) and Ru(0001) is dominated by the Moire pattern of graphene. CuPc molecules form well-ordered structures with rectangular unit cells on graphene/Ru(10 anti 10) and Ru(0001). The distance of adjacent CuPc molecules is 15±0.5 Aa and 13±0.5 Aa on graphene/Ru(0001

  10. Magnetic capture of polydopamine-encapsulated Hela cells for the analysis of cell surface proteins.

    Science.gov (United States)

    Liu, Yiying; Yan, Guoquan; Gao, Mingxia; Zhang, Xiangmin

    2018-02-10

    A novel method to characterize cell surface proteins and complexes has been developed. Polydopamine (PDA)-encapsulated Hela cells were prepared for plasma membrane proteome research. Since the PDA protection, the encapsulated cells could be maintained for more than two weeks. Amino groups functionalized magnetic nanoparticles were also used for cell capture by the reaction with the PDA coatings. Plasma membrane fragments were isolated and enriched with assistance of an external magnetic field after disruption of the coated cells by ultrasonic treatment. Plasma membrane proteins (PMPs) and complexes were well preserved on the fragments and identified by shot-gun proteomic analytical strategy. 385 PMPs and 1411 non-PMPs were identified using the method. 85.2% of these PMPs were lipid-raft associated proteins. Ingenuity Pathway Analysis was employed for bio-information extraction from the identified proteins. It was found that 653 non-PMPs had interactions with 140 PMPs. Among them, epidermal growth factor receptor and its complexes, and a series of important pathways including STAT3 pathway were observed. All these results demonstrated that the new approach is of great importance in applying to the research of physiological function and mechanism of the plasma membrane proteins. This work developed a novel strategy for the proteomic analysis of cell surface proteins. According to the results, 73.3% of total identified proteins were lipid-raft associated proteins, which imply that the proposed method is of great potential in the identification of lipid-raft associated proteins. In addition, a series of protein-protein interactions and pathways related to Hela cells were pointed out. All these results demonstrated that our proposed approach is of great importance and could well be applied to the physiological function and mechanism research of plasma membrane proteins. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Cardiomyocyte differentiation of embryonic stem cells on the surface of organic semiconductors.

    Science.gov (United States)

    Caserta, Sergio; Barra, Mario; Manganelli, Genesia; Tomaiuolo, Giovanna; Filosa, Stefania; Cassinese, Antonio; Guido, Stefano

    2013-06-25

    Electrically active supports provide new horizons for bio-sensing and artificial organ design. Cell-based electrochemical biosensors can be used as bio-microactuators, applied to the biorobotics. Microchip-based bioassay systems can provide real-time cell analysis for preclinical drug design or for intelligent drug delivery devices. In regenerative medicine, electrically active supports can be used as bio-reactors to monitor cell activity, optimize the stem cell differentiation and control cell and tissue morphology. Biocompatibility and direct interaction of the electrically active surface with the cell surface is a critical aspect of this technology.
 In this work embryonic stem cells (AK7 ES) have been cultivated on the surface of thin films achieved through the evaporation of two aromatic compounds (T6 and PDI-8CN2 ) of particular interest for the fabrication of organic field-effect transistors (OFET). One of the potential advantages offered by the application of OFETs as bio-electronic supports is that they represent a powerful tool for the detection of bio-signals because their electrically active surface is an organic film.
 The cell morphology on T6 and PDI-8CN2 surface shows to be similar to the usual cell appearance, as obtained when standard culture support (petri dish) are employed. Moreover, our experimental results demonstrate that stem cells can be lead to differentiation up to "beating" cardiomyocytes even on these electrically-active organic films.
 This investigation encourages the perspective to develop OFET-based biosensors in order to accurately characterize stem cells during the cardiac differentiation process and eventually increase their differentiation efficiency.

  12. Non-interacting surface solvation and dynamics in protein-protein interactions

    NARCIS (Netherlands)

    Visscher, Koen M.; Kastritis, Panagiotis L.|info:eu-repo/dai/nl/315886668; Bonvin, Alexandre M J J|info:eu-repo/dai/nl/113691238

    2015-01-01

    Protein-protein interactions control a plethora of cellular processes, including cell proliferation, differentiation, apoptosis, and signal transduction. Understanding how and why proteins interact will inevitably lead to novel structure-based drug design methods, as well as design of de novo

  13. Different cell fates from cell-cell interactions: core architectures of two-cell bistable networks.

    Science.gov (United States)

    Rouault, Hervé; Hakim, Vincent

    2012-02-08

    The acquisition of different fates by cells that are initially in the same state is central to development. Here, we investigate the possible structures of bistable genetic networks that can allow two identical cells to acquire different fates through cell-cell interactions. Cell-autonomous bistable networks have been previously sampled using an evolutionary algorithm. We extend this evolutionary procedure to take into account interactions between cells. We obtain a variety of simple bistable networks that we classify into major subtypes. Some have long been proposed in the context of lateral inhibition through the Notch-Delta pathway, some have been more recently considered and others appear to be new and based on mechanisms not previously considered. The results highlight the role of posttranscriptional interactions and particularly of protein complexation and sequestration, which can replace cooperativity in transcriptional interactions. Some bistable networks are entirely based on posttranscriptional interactions and the simplest of these is found to lead, upon a single parameter change, to oscillations in the two cells with opposite phases. We provide qualitative explanations as well as mathematical analyses of the dynamical behaviors of various created networks. The results should help to identify and understand genetic structures implicated in cell-cell interactions and differentiation. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  14. Pancreatic hormones are expressed on the surfaces of human and rat islet cells through exocytotic sites

    DEFF Research Database (Denmark)

    Larsson, L I; Hutton, J C; Madsen, O D

    1989-01-01

    . Electron microscopy reveals the labeling to occur at sites of exocytotic granule release, involving the surfaces of extruded granule cores. The surfaces of islet cells were labeled both by polyclonal and monoclonal antibodies, excluding that receptor-interacting, anti-idiotypic hormone antibodies were...... for these results. It is concluded that the staining reflects interactions between the appropriate antibodies and exocytotic sites of hormone release....

  15. Interaction of multi-walled carbon nanotubes with perfluorinated sulfonic acid ionomers and surface treatment studies

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Dhiman, Rajnish; Borghei, Maryam

    2014-01-01

    The interaction between high surface area nano-carbon catalyst supports for proton exchange membrane fuel cells (PEMFCs) and perfluorinated sulfonic acid (Nafion®) ionomer was studied 19 fluorine nuclear magnetic resonance spectroscopy (19F-NMR). The method was developed and improved for more...

  16. The anticancer activity of lytic peptides is inhibited by heparan sulfate on the surface of the tumor cells

    Science.gov (United States)

    2009-01-01

    Background Cationic antimicrobial peptides (CAPs) with antitumor activity constitute a promising group of novel anticancer agents. These peptides induce lysis of cancer cells through interactions with the plasma membrane. It is not known which cancer cell membrane components influence their susceptibility to CAPs. We have previously shown that CAPs interact with the two glycosaminoglycans (GAGs), heparan sulfate (HS) and chondroitin sulfate (CS), which are present on the surface of most cells. The purpose of this study was to investigate the role of the two GAGs in the cytotoxic activity of CAPs. Methods Various cell lines, expressing different levels of cell surface GAGs, were exposed to bovine lactoferricin (LfcinB) and the designer peptide, KW5. The cytotoxic effect of the peptides was investigated by use of the colorimetric MTT viability assay. The cytotoxic effect on wild type CHO cells, expressing normal amounts of GAGs on the cell surface, and the mutant pgsA-745, that has no expression of GAGs on the cell surface, was also investigated. Results We show that cells not expressing HS were more susceptible to CAPs than cells expressing HS at the cell surface. Further, exogenously added heparin inhibited the cytotoxic effect of the peptides. Chondroitin sulfate had no effect on the cytotoxic activity of KW5 and only minor effects on LfcinB cytotoxicity. Conclusion Our results show for the first time that negatively charged molecules at the surface of cancer cells inhibit the cytotoxic activity of CAPs. Our results indicate that HS at the surface of cancer cells sequesters CAPs away from the phospholipid bilayer and thereby impede their ability to induce cytolysis. PMID:19527490

  17. The anticancer activity of lytic peptides is inhibited by heparan sulfate on the surface of the tumor cells

    Directory of Open Access Journals (Sweden)

    Rekdal Øystein

    2009-06-01

    Full Text Available Abstract Background Cationic antimicrobial peptides (CAPs with antitumor activity constitute a promising group of novel anticancer agents. These peptides induce lysis of cancer cells through interactions with the plasma membrane. It is not known which cancer cell membrane components influence their susceptibility to CAPs. We have previously shown that CAPs interact with the two glycosaminoglycans (GAGs, heparan sulfate (HS and chondroitin sulfate (CS, which are present on the surface of most cells. The purpose of this study was to investigate the role of the two GAGs in the cytotoxic activity of CAPs. Methods Various cell lines, expressing different levels of cell surface GAGs, were exposed to bovine lactoferricin (LfcinB and the designer peptide, KW5. The cytotoxic effect of the peptides was investigated by use of the colorimetric MTT viability assay. The cytotoxic effect on wild type CHO cells, expressing normal amounts of GAGs on the cell surface, and the mutant pgsA-745, that has no expression of GAGs on the cell surface, was also investigated. Results We show that cells not expressing HS were more susceptible to CAPs than cells expressing HS at the cell surface. Further, exogenously added heparin inhibited the cytotoxic effect of the peptides. Chondroitin sulfate had no effect on the cytotoxic activity of KW5 and only minor effects on LfcinB cytotoxicity. Conclusion Our results show for the first time that negatively charged molecules at the surface of cancer cells inhibit the cytotoxic activity of CAPs. Our results indicate that HS at the surface of cancer cells sequesters CAPs away from the phospholipid bilayer and thereby impede their ability to induce cytolysis.

  18. Study of the adhesion interaction using 51Cr labelling method between the myeloma cell lines and the endothelial cells

    International Nuclear Information System (INIS)

    Zhang Xueguang; Wang Jiangfang; Mao Zijun

    1995-06-01

    Using 51 Cr labelled multiple myeloma (MM) cell lines U266/XG-7, the regulatory effect of cytokines on the adhesive interaction between myeloma-cell lines U266/XG-7 and the endothelial cells, and the effects of these cytokines on expression of adhesion molecules and secretion of other cytokines were studied. The experimental results were as follows: (1) IL-6 and IL-6 Rgp 130-associated growth factors (such as GM-CSF) are not only myeloma cell growth factors, but also can enhance the adhesion between MM cells and endothelial cells and thus facilitated the metastasis of tumor cells. (2) Cytokines could induce increase in the expression of CD54 and CD44 on the endothelial cells and the secretion of IL-6 and TNF by the endothelial cells. On the other hand, the adhesion could also cause the change of CD11a, CD54, CD44 and VLA-4 on surface of myeloma cells XG-7. Finally, the interaction between MM cells and stromal cells from murine bone marrow could rapidly induce autocrine of IL-6 in human IL-6-dependent MM cells. (3) The interaction between stromal cells and tumor cells regulated by the cytokines and adhesion molecules was a key element in the pathogenesis and development of human MM. Among these factors, VLA-4 might be one of the molecules involved in U266/XG-7-EC interaction. (5 tabs., 8 figs.)

  19. Diffusion of MMPs on the Surface of Collagen Fibrils: The Mobile Cell Surface – Collagen Substratum Interface

    Science.gov (United States)

    Collier, Ivan E.; Legant, Wesley; Marmer, Barry; Lubman, Olga; Saffarian, Saveez; Wakatsuki, Tetsuro; Elson, Elliot; Goldberg, Gregory I.

    2011-01-01

    Remodeling of the extracellular matrix catalyzed by MMPs is central to morphogenetic phenomena during development and wound healing as well as in numerous pathologic conditions such as fibrosis and cancer. We have previously demonstrated that secreted MMP-2 is tethered to the cell surface and activated by MT1-MMP/TIMP-2-dependent mechanism. The resulting cell-surface collagenolytic complex (MT1-MMP)2/TIMP-2/MMP-2 can initiate (MT1-MMP) and complete (MMP-2) degradation of an underlying collagen fibril. The following question remained: What is the mechanism of substrate recognition involving the two structures of relatively restricted mobility, the cell surface enzymatic complex and a collagen fibril embedded in the ECM? Here we demonstrate that all the components of the complex are capable of processive movement on a surface of the collagen fibril. The mechanism of MT1-MMP movement is a biased diffusion with the bias component dependent on the proteolysis of its substrate, not adenosine triphosphate (ATP) hydrolysis. It is similar to that of the MMP-1 Brownian ratchet we described earlier. In addition, both MMP-2 and MMP-9 as well as their respective complexes with TIMP-1 and -2 are capable of Brownian diffusion on the surface of native collagen fibrils without noticeable dissociation while the dimerization of MMP-9 renders the enzyme immobile. Most instructive is the finding that the inactivation of the enzymatic activity of MT1-MMP has a detectable negative effect on the cell force developed in miniaturized 3D tissue constructs. We propose that the collagenolytic complex (MT1-MMP)2/TIMP-2/MMP-2 represents a Mobile Cell Surface – Collagen Substratum Interface. The biological implications of MT1-MMP acting as a molecular ratchet tethered to the cell surface in complex with MMP-2 suggest a new mechanism for the role of spatially regulated peri-cellular proteolysis in cell-matrix interactions. PMID:21912660

  20. Well-Controlled Cell-Trapping Systems for Investigating Heterogeneous Cell-Cell Interactions.

    Science.gov (United States)

    Kamiya, Koki; Abe, Yuta; Inoue, Kosuke; Osaki, Toshihisa; Kawano, Ryuji; Miki, Norihisa; Takeuchi, Shoji

    2018-03-01

    Microfluidic systems have been developed for patterning single cells to study cell-cell interactions. However, patterning multiple types of cells to understand heterogeneous cell-cell interactions remains difficult. Here, it is aimed to develop a cell-trapping device to assemble multiple types of cells in the well-controlled order and morphology. This device mainly comprises a parylene sheet for assembling cells and a microcomb for controlling the cell-trapping area. The cell-trapping area is controlled by moving the parylene sheet on an SU-8 microcomb using tweezers. Gentle downward flow is used as a driving force for the cell-trapping. The assembly of cells on a parylene sheet with round and line-shaped apertures is demonstrated. The cell-cell contacts of the trapped cells are then investigated by direct cell-cell transfer of calcein via connexin nanopores. Finally, using the device with a system for controlling the cell-trapping area, three different types of cells in the well-controlled order are assembled. The correct cell order rate obtained using the device is 27.9%, which is higher than that obtained without the sliding parylene system (0.74%). Furthermore, the occurrence of cell-cell contact between the three cell types assembled is verified. This cell-patterning device will be a useful tool for investigating heterogeneous cell-cell interactions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Cell Surface Properties of Lactococcus lactis Reveal Milk Protein Binding Specifically Evolved in Dairy Isolates

    Directory of Open Access Journals (Sweden)

    Mariya Tarazanova

    2017-09-01

    Full Text Available Surface properties of bacteria are determined by the molecular composition of the cell wall and they are important for interactions of cells with their environment. Well-known examples of bacterial interactions with surfaces are biofilm formation and the fermentation of solid materials like food and feed. Lactococcus lactis is broadly used for the fermentation of cheese and buttermilk and it is primarily isolated from either plant material or the dairy environment. In this study, we characterized surface hydrophobicity, charge, emulsification properties, and the attachment to milk proteins of 55 L. lactis strains in stationary and exponential growth phases. The attachment to milk protein was assessed through a newly developed flow cytometry-based protocol. Besides finding a high degree of biodiversity, phenotype-genotype matching allowed the identification of candidate genes involved in the modification of the cell surface. Overexpression and gene deletion analysis allowed to verify the predictions for three identified proteins that altered surface hydrophobicity and attachment of milk proteins. The data also showed that lactococci isolated from a dairy environment bind higher amounts of milk proteins when compared to plant isolates. It remains to be determined whether the alteration of surface properties also has potential to alter starter culture functionalities.

  2. Cell Surface Properties of Lactococcus lactis Reveal Milk Protein Binding Specifically Evolved in Dairy Isolates

    Science.gov (United States)

    Tarazanova, Mariya; Huppertz, Thom; Beerthuyzen, Marke; van Schalkwijk, Saskia; Janssen, Patrick; Wels, Michiel; Kok, Jan; Bachmann, Herwig

    2017-01-01

    Surface properties of bacteria are determined by the molecular composition of the cell wall and they are important for interactions of cells with their environment. Well-known examples of bacterial interactions with surfaces are biofilm formation and the fermentation of solid materials like food and feed. Lactococcus lactis is broadly used for the fermentation of cheese and buttermilk and it is primarily isolated from either plant material or the dairy environment. In this study, we characterized surface hydrophobicity, charge, emulsification properties, and the attachment to milk proteins of 55 L. lactis strains in stationary and exponential growth phases. The attachment to milk protein was assessed through a newly developed flow cytometry-based protocol. Besides finding a high degree of biodiversity, phenotype-genotype matching allowed the identification of candidate genes involved in the modification of the cell surface. Overexpression and gene deletion analysis allowed to verify the predictions for three identified proteins that altered surface hydrophobicity and attachment of milk proteins. The data also showed that lactococci isolated from a dairy environment bind higher amounts of milk proteins when compared to plant isolates. It remains to be determined whether the alteration of surface properties also has potential to alter starter culture functionalities. PMID:28936202

  3. Asperity interaction in adhesive contact of metallic rough surfaces

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    The analysis of adhesive contact of metallic rough surfaces considering the effect of asperity interaction is the subject of this investigation. The micro-contact model of asperity interactions developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64) is combined with the elastic plastic adhesive contact model developed by Chang et al (1988 Trans. ASME: J. Tribol. 110 50-6) to consider the asperity interaction and elastic-plastic deformation in the presence of surface forces simultaneously. The well-established elastic adhesion index and plasticity index are used to consider the different contact conditions. Results show that asperity interaction influences the load-separation behaviour in elastic-plastic adhesive contact of metallic rough surfaces significantly and, in general, adhesion is reduced due to asperity interactions

  4. Heparanase facilitates cell adhesion and spreading by clustering of cell surface heparan sulfate proteoglycans.

    Directory of Open Access Journals (Sweden)

    Flonia Levy-Adam

    2008-06-01

    Full Text Available Heparanase is a heparan sulfate (HS degrading endoglycosidase participating in extracellular matrix degradation and remodeling. Apart of its well characterized enzymatic activity, heparanase was noted to exert also enzymatic-independent functions. Non-enzymatic activities of heparanase include enhanced adhesion of tumor-derived cells and primary T-cells. Attempting to identify functional domains of heparanase that would serve as targets for drug development, we have identified heparin binding domains of heparanase. A corresponding peptide (residues Lys(158-Asp(171, termed KKDC was demonstrated to physically associate with heparin and HS, and to inhibit heparanase enzymatic activity. We hypothesized that the pro-adhesive properties of heparanase are mediated by its interaction with cell surface HS proteoglycans, and utilized the KKDC peptide to examine this possibility. We provide evidence that the KKDC peptide interacts with cell membrane HS, resulting in clustering of syndecan-1 and syndecan-4. We applied classical analysis of cell morphology, fluorescent and time-lapse microscopy and demonstrated that the KKDC peptide efficiently stimulates the adhesion and spreading of various cell types, mediated by PKC, Src, and the small GTPase Rac1. These results support, and further substantiate the notion that heparanase function is not limited to its enzymatic activity.

  5. Plasma–Surface Interactions Under High Heat and Particle Fluxes

    Directory of Open Access Journals (Sweden)

    Gregory De Temmerman

    2013-01-01

    Full Text Available The plasma-surface interactions expected in the divertor of a future fusion reactor are characterized by extreme heat and particle fluxes interacting with the plasma-facing surfaces. Powerful linear plasma generators are used to reproduce the expected plasma conditions and allow plasma-surface interactions studies under those very harsh conditions. While the ion energies on the divertor surfaces of a fusion device are comparable to those used in various plasma-assited deposition and etching techniques, the ion (and energy fluxes are up to four orders of magnitude higher. This large upscale in particle flux maintains the surface under highly non-equilibrium conditions and bring new effects to light, some of which will be described in this paper.

  6. Large-Scale Investigation of Leishmania Interaction Networks with Host Extracellular Matrix by Surface Plasmon Resonance Imaging

    Science.gov (United States)

    Fatoux-Ardore, Marie; Peysselon, Franck; Weiss, Anthony; Bastien, Patrick; Pratlong, Francine

    2014-01-01

    We have set up an assay to study the interactions of live pathogens with their hosts by using protein and glycosaminoglycan arrays probed by surface plasmon resonance imaging. We have used this assay to characterize the interactions of Leishmania promastigotes with ∼70 mammalian host biomolecules (extracellular proteins, glycosaminoglycans, growth factors, cell surface receptors). We have identified, in total, 27 new partners (23 proteins, 4 glycosaminoglycans) of procyclic promastigotes of six Leishmania species and 18 partners (15 proteins, 3 glycosaminoglycans) of three species of stationary-phase promastigotes for all the strains tested. The diversity of the interaction repertoires of Leishmania parasites reflects their dynamic and complex interplay with their mammalian hosts, which depends mostly on the species and strains of Leishmania. Stationary-phase Leishmania parasites target extracellular matrix proteins and glycosaminoglycans, which are highly connected in the extracellular interaction network. Heparin and heparan sulfate bind to most Leishmania strains tested, and 6-O-sulfate groups play a crucial role in these interactions. Numerous Leishmania strains bind to tropoelastin, and some strains are even able to degrade it. Several strains interact with collagen VI, which is expressed by macrophages. Most Leishmania promastigotes interact with several regulators of angiogenesis, including antiangiogenic factors (endostatin, anastellin) and proangiogenic factors (ECM-1, VEGF, and TEM8 [also known as anthrax toxin receptor 1]), which are regulated by hypoxia. Since hypoxia modulates the infection of macrophages by the parasites, these interactions might influence the infection of host cells by Leishmania. PMID:24478075

  7. Computational design of protein interactions: designing proteins that neutralize influenza by inhibiting its hemagglutinin surface protein

    Science.gov (United States)

    Fleishman, Sarel

    2012-02-01

    Molecular recognition underlies all life processes. Design of interactions not seen in nature is a test of our understanding of molecular recognition and could unlock the vast potential of subtle control over molecular interaction networks, allowing the design of novel diagnostics and therapeutics for basic and applied research. We developed the first general method for designing protein interactions. The method starts by computing a region of high affinity interactions between dismembered amino acid residues and the target surface and then identifying proteins that can harbor these residues. Designs are tested experimentally for binding the target surface and successful ones are affinity matured using yeast cell surface display. Applied to the conserved stem region of influenza hemagglutinin we designed two unrelated proteins that, following affinity maturation, bound hemagglutinin at subnanomolar dissociation constants. Co-crystal structures of hemagglutinin bound to the two designed binders were within 1Angstrom RMSd of their models, validating the accuracy of the design strategy. One of the designed proteins inhibits the conformational changes that underlie hemagglutinin's cell-invasion functions and blocks virus infectivity in cell culture, suggesting that such proteins may in future serve as diagnostics and antivirals against a wide range of pathogenic influenza strains. We have used this method to obtain experimentally validated binders of several other target proteins, demonstrating the generality of the approach. We discuss the combination of modeling and high-throughput characterization of design variants which has been key to the success of this approach, as well as how we have used the data obtained in this project to enhance our understanding of molecular recognition. References: Science 332:816 JMB, in press Protein Sci 20:753

  8. Interactions between kaolinite Al−OH surface and sodium hexametaphosphate

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yonghua, E-mail: hyh19891102@163.com [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Liu, Wenli; Zhou, Jia [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chen, Jianhua [College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China)

    2016-11-30

    Highlights: • Sodium hexametaphosphate (NaHMP) can adsorb on kaolinite Al−OH terminated (001) surface easily. • The oxygen atoms of hexametaphosphate form strong hydrogen bonds with the hydrogen atoms of kaolinite Al−OH surface. • The electrostatic force is the main interaction between NaHMP and Al−OH surface. • The linear hexaphosphate −[PO{sub 3}]{sub m}− chains adsorb stably than −[HPO{sub 3}]{sub m}− chains. - Abstract: To investigate the dispersion mechanism of sodium hexametaphosphate on kaolinite particles, we simulated the interaction between linear polyphosphate chains and kaolinite Al−OH terminated surface by molecular dynamics, as well as the interaction between the [HPO{sub 4}]{sup 2−} anion and kaolinite Al−OH surface by density functional theory (DFT). The calculated results demonstrate that hexametaphosphate can be adsorbed by the kaolinite Al−OH surface. The oxygen atoms of hexametaphosphate anions may receive many electrons from the Al−OH surface and form hydrogen bonds with the hydrogen atoms of surface hydroxyl groups. Moreover, electrostatic force dominates the interactions between hexametaphosphate anions and kaolinite Al−OH surface. Therefore, after the adsorption of hexametaphosphate on kaolinite Al−OH surface, the kaolinite particles carry more negative charge and the electrostatic repulsion between particles increases. In addition, the adsorption of −[PO{sub 3}]{sub m}− species on the Al−OH surface should be more stable than the adsorption of −[HPO{sub 3}]{sub m}− species.

  9. Tolerogenic interactions between CD8+ dendritic cells and NKT cells prevent rejection of bone marrow and organ grafts.

    Science.gov (United States)

    Hongo, David; Tang, Xiaobin; Zhang, Xiangyue; Engleman, Edgar G; Strober, Samuel

    2017-03-23

    The combination of total lymphoid irradiation and anti-T-cell antibodies safely induces immune tolerance to combined hematopoietic cell and organ allografts in humans. Our mouse model required host natural killer T (NKT) cells to induce tolerance. Because NKT cells normally depend on signals from CD8 + dendritic cells (DCs) for their activation, we used the mouse model to test the hypothesis that, after lymphoid irradiation, host CD8 + DCs play a requisite role in tolerance induction through interactions with NKT cells. Selective deficiency of either CD8 + DCs or NKT cells abrogated chimerism and organ graft acceptance. After radiation, the CD8 + DCs increased expression of surface molecules required for NKT and apoptotic cell interactions and developed suppressive immune functions, including production of indoleamine 2,3-deoxygenase. Injection of naive mice with apoptotic spleen cells generated by irradiation led to DC changes similar to those induced by lymphoid radiation, suggesting that apoptotic body ingestion by CD8 + DCs initiates tolerance induction. Tolerogenic CD8 + DCs induced the development of tolerogenic NKT cells with a marked T helper 2 cell bias that, in turn, regulated the differentiation of the DCs and suppressed rejection of the transplants. Thus, reciprocal interactions between CD8 + DCs and invariant NKT cells are required for tolerance induction in this system that was translated into a successful clinical protocol. © 2017 by The American Society of Hematology.

  10. Microfluidic biofunctionalisation protocols to form multi-valent interactions for cell rolling and phenotype modification investigations

    KAUST Repository

    Perozziello, Gerardo

    2013-07-01

    In this study, we propose a fast, simple method to biofunctionalise microfluidic systems for cellomic investigations based on micro-fluidic protocols. Many available processes either require expensive and time-consuming protocols or are incompatible with the fabrication of microfluidic systems. Our method differs from the existing since it is applicable to an assembled system, uses few microlitres of reagents and it is based on the use of microbeads. The microbeads have specific surface moieties to link the biomolecules and couple cell receptors. Furthermore, the microbeads serve as arm spacer and offer the benefit of the multi-valent interaction. Microfluidics was adapted together with topology and biochemistry surface modifications to offer the microenvironment for cellomic studies. Based on this principle, we exploit the streptavidin-biotin interaction to couple antibodies to the biofunctionalised microfluidic environment within 5 h using 200 μL of reagents and biomolecules. We selected the antibodies able to form complexes with the MHC class I (MHC-I) molecules present on the cell membrane and involved in the immune surveillance. To test the microfluidic system, tumour cell lines (RMA) were rolled across the coupled antibodies to recognise and strip MHC-I molecules. As result, we show that cell rolling performed inside a microfluidic chamber functionalised with beads and the opportune antibody facilitate the removal of MHC class I molecules. We showed that the level of median fluorescent intensity of the MHC-I molecules is 300 for cells treated in a not biofunctionalised surface. It decreased to 275 for cells treated in a flat biofunctionalised surface and to 250 for cells treated on a surface where biofunctionalised microbeads were immobilised. The cells with reduced expression of MHC-I molecules showed, after cytotoxicity tests, susceptibility 3.5 times higher than normal cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Free-zone electrophoresis of animal cells. 1: Experiments on cell-cell interactions

    Science.gov (United States)

    Todd, P. W.; Hjerten, S.

    1985-01-01

    The electrophoretically migrating zones wasa monitored. The absence of fluid flows in the direction of migration permits direct measurement of electrophoretic velocities of any material. Sedimentation is orthogonal to electrokinetic motion and the effects of particle-particle interaction on electrophoretic mobility is studied by free zone electrophoresis. Fixed erythrocytes at high concentrations, mixtures of fixed erythrocytes from different animal species, and mixtures of cultured human cells were studied in low ionic strength buffers. The electrophoretic velocity of fixed erythrocytes was not altered by increasing cell concentration or by the mixing of erythrocytes from different species. When zones containing cultured human glial cells and neuroblastoma cells are permitted to interact during electrophoresis, altered migration patterns occur. It is found that cell-cell interactions depends upon cell type.

  12. Multilayer Choline Phosphate Molecule Modified Surface with Enhanced Cell Adhesion but Resistance to Protein Adsorption.

    Science.gov (United States)

    Chen, Xingyu; Yang, Ming; Liu, Botao; Li, Zhiqiang; Tan, Hong; Li, Jianshu

    2017-08-22

    Choline phosphate (CP), which is a new zwitterionic molecule, and has the reverse order of phosphate choline (PC) and could bind to the cell membrane though the unique CP-PC interaction. Here we modified a glass surface with multilayer CP molecules using surface-initiated atom-transfer radical polymerization (SI-ATRP) and the ring-opening method. Polymeric brushes of (dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by SI-ATRP from the glass surface. Then the grafted PDMAEMA brushes were used to introduce CP groups to fabricate the multilayer CP molecule modified surface. The protein adsorption experiment and cell culture test were used to evaluate the biocompatibility of the modified surfaces by using human umbilical veinendothelial cells (HUVECs). The protein adsorption results demonstrated that the multilayer CP molecule decorated surface could prevent the adsorption of fibrinogen and serum protein. The adhesion and proliferation of cells were improved significantly on the multilayer CP molecule modified surface. Therefore, the biocompatibility of the material surface could be improved by the modified multilayer CP molecule, which exhibits great potential for biomedical applications, e.g., scaffolds in tissue engineering.

  13. Surface Hydrophilicity of Poly(l-Lactide Acid Polymer Film Changes the Human Adult Adipose Stem Cell Architecture

    Directory of Open Access Journals (Sweden)

    Chiara Argentati

    2018-02-01

    Full Text Available Current knowledge indicates that the molecular cross-talk between stem cells and biomaterials guides the stem cells’ fate within a tissue engineering system. In this work, we have explored the effects of the interaction between the poly(l-lactide acid (PLLA polymer film and human adult adipose stem cells (hASCs, focusing on the events correlating the materials’ surface characteristics and the cells’ plasma membrane. hASCs were seeded on films of pristine PLLA polymer and on a PLLA surface modified by the radiofrequency plasma method under oxygen flow (PLLA+O2. Comparative experiments were performed using human bone-marrow mesenchymal stem cells (hBM-MSCs and human umbilical matrix stem cells (hUCMSCs. After treatment with oxygen-plasma, the surface of PLLA films became hydrophilic, whereas the bulk properties were not affected. hASCs cultured on pristine PLLA polymer films acquired a spheroid conformation. On the contrary, hASCs seeded on PLLA+O2 film surface maintained the fibroblast-like morphology typically observed on tissue culture polystyrene. This suggests that the surface hydrophilicity is involved in the acquisition of the spheroid conformation. Noteworthy, the oxygen treatment had no effects on hBM-MSC and hUCMSC cultures and both stem cells maintained the same shape observed on PLLA films. This different behavior suggests that the biomaterial-interaction is stem cell specific.

  14. Inclusion of gold nanoparticles in meso-porous silicon for the SERS analysis of cell adhesion on nano-structured surfaces

    KAUST Repository

    Coluccio, M.L.

    2016-03-25

    The study and the comprehension of the mechanism of cell adhesion and cell interaction with a substrate is a key point when biology and medicine meet engineering. This is the case of several biomedical applications, from regenerative medicine and tissue engineering to lab on chip and many others, in which the realization of the appropriate artificial surface allows the control of cell adhesion and proliferation. In this context, we aimed to design and develop a fabrication method of mesoporous (MeP) silicon substrates, doped with gold nanoparticles, in which we combine the capability of porous surfaces to support cell adhesion with the SERS capabilities of gold nanoparticles, to understand the chemical mechanisms of cell/surface interaction. MeP Si surfaces were realized by anodization of a Si wafer, creating the device for cell adhesion and growth. Gold nanoparticles were deposited on porous silicon by an electroless technique. We thus obtained devices with superior SERS capabilities, whereby cell activity may be controlled using Raman spectroscopy. MCF-7 breast cancer cells were cultured on the described substrates and SERS maps revealing the different expression and distribution of adhesion molecules were obtained by Raman spectroscopic analyses.

  15. Identification of novel direct protein-protein interactions by irradiating living cells with femtosecond UV laser pulses.

    Science.gov (United States)

    Itri, Francesco; Monti, Daria Maria; Chino, Marco; Vinciguerra, Roberto; Altucci, Carlo; Lombardi, Angela; Piccoli, Renata; Birolo, Leila; Arciello, Angela

    2017-10-07

    The identification of protein-protein interaction networks in living cells is becoming increasingly fundamental to elucidate main biological processes and to understand disease molecular bases on a system-wide level. We recently described a method (LUCK, Laser UV Cross-linKing) to cross-link interacting protein surfaces in living cells by UV laser irradiation. By using this innovative methodology, that does not require any protein modification or cell engineering, here we demonstrate that, upon UV laser irradiation of HeLa cells, a direct interaction between GAPDH and alpha-enolase was "frozen" by a cross-linking event. We validated the occurrence of this direct interaction by co-immunoprecipitation and Immuno-FRET analyses. This represents a proof of principle of the LUCK capability to reveal direct protein interactions in their physiological environment. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Interactive Design of Developable Surfaces

    KAUST Repository

    Tang, Chengcheng

    2016-01-15

    We present a new approach to geometric modeling with developable surfaces and the design of curved-creased origami. We represent developables as splines and express the nonlinear conditions relating to developability and curved folds as quadratic equations. This allows us to utilize a constraint solver, which may be described as energy-guided projection onto the constraint manifold, and which is fast enough for interactive modeling. Further, a combined primal-dual surface representation enables us to robustly and quickly solve approximation problems.

  17. Interactive Design of Developable Surfaces

    KAUST Repository

    Tang, Chengcheng; Bo, Pengbo; Wallner, Johannes; Pottmann, Helmut

    2016-01-01

    We present a new approach to geometric modeling with developable surfaces and the design of curved-creased origami. We represent developables as splines and express the nonlinear conditions relating to developability and curved folds as quadratic equations. This allows us to utilize a constraint solver, which may be described as energy-guided projection onto the constraint manifold, and which is fast enough for interactive modeling. Further, a combined primal-dual surface representation enables us to robustly and quickly solve approximation problems.

  18. Interactions of the cell-wall glycopolymers of lactic acid bacteria with their bacteriophages

    Directory of Open Access Journals (Sweden)

    Marie-Pierre eChapot-Chartier

    2014-05-01

    Full Text Available Lactic acid bacteria (LAB are Gram positive bacteria widely used in the production of fermented food in particular cheese and yoghurts. Bacteriophage infections during fermentation processes have been for many years a major industrial concern and have stimulated numerous research efforts. Better understanding of the molecular mechanisms of bacteriophage interactions with their host bacteria is required for the development of efficient strategies to fight against infections. The bacterial cell wall plays key roles in these interactions. First, bacteriophages must adsorb at the bacterial surface through specific interactions with receptors that are cell wall components. At next step, phages must overcome the barrier constituted by cell wall peptidoglycan to inject DNA inside bacterial cell. Also at the end of the infection cycle, phages synthesize endolysins able to hydrolyze peptidoglycan and lyse bacterial cells to release phage progeny. In the last decade, concomitant development of genomics and structural analysis of cell wall components allowed considerable advances in the knowledge of their structure and function in several model LAB. Here, we describe the present knowledge on the structure of the cell wall glycopolymers of the best characterized LAB emphasizing their structural variations and we present the available data regarding their role in bacteria-phage specific interactions at the different steps of the infection cycle.

  19. Heparan sulfate proteoglycans on the cell surface: versatile coordinators of cellular functions

    DEFF Research Database (Denmark)

    Tumova, S; Woods, A; Couchman, J R

    2000-01-01

    Heparan sulfate proteoglycans are complex molecules composed of a core protein with covalently attached glycosaminoglycan chains. While the protein part determines localization of the proteoglycan on the cell surfaces or in the extracellular matrix, the glycosaminoglycan component, heparan sulfate......, mediates interactions with a variety of extracellular ligands such as growth factors and adhesion molecules. Through these interactions, heparan sulfate proteoglycans participate in many events during cell adhesion, migration, proliferation and differentiation. We are determining the multitude...... of proteoglycan functions, as their intricate roles in many pathways are revealed. They act as coreceptors for growth factors, participate in signalling during cell adhesion, modulate the activity of a broad range of molecules, and partake in many developmental and pathological processes, including tumorigenesis...

  20. Multicellular tumor spheroid interactions with bone cells and bone

    International Nuclear Information System (INIS)

    Wezeman, F.H.; Guzzino, K.M.; Waxler, B.

    1985-01-01

    In vitro coculture techniques were used to study HSDM1C1 murine fibrosarcoma multicellular tumor spheroid (HSDM1C1-MTS) interactions with mouse calvarial bone cells having osteoblastic characteristics and mouse bone explants. HSDM1C1-MTS attached to confluent bone cell monolayers and their attachment rate was quantified. HSDM1C1-MTS interaction with bone cells was further demonstrated by the release of 3 H-deoxyuridine from prelabeled bone cells during coculture with multicellular tumor spheroids. HSDM1C1-MTS-induced cytotoxicity was mimicked by the addition of 10(-5) M prostaglandin E2 (PGE2) to 3 H-deoxyuridine-labeled bone cells. The effects of low (10(-9) M) and high (10(-5) M) concentrations of PGE2 on bone cell proliferation were also studied. Higher concentrations of PGE2 inhibited bone cell proliferation. HSDM1C1-MTS resorbed living explants in the presence of indomethacin, suggesting that other tumor cell products may also participate in bone resorption. HSDM1C1-MTS caused direct bone resorption as measured by the significantly elevated release of 45 Ca from prelabeled, devitalized calvaria. However, the growth of a confluent bone cell layer on devitalized, 45 Ca-prelabeled calvaria resulted in a significant reduction in the amount of 45 Ca released subsequent to the seeding of HSDM1C1-MTS onto the explants. Bone cells at the bone surface may act as a barrier against invasion and tumor cell-mediated bone resorption. Violation of this cellular barrier is achieved, in part, by tumor cell products

  1. Local cell metrics: a novel method for analysis of cell-cell interactions

    Directory of Open Access Journals (Sweden)

    Chen Chien-Chiang

    2009-10-01

    Full Text Available Abstract Background The regulation of many cell functions is inherently linked to cell-cell contact interactions. However, effects of contact interactions among adherent cells can be difficult to detect with global summary statistics due to the localized nature and noise inherent to cell-cell interactions. The lack of informatics approaches specific for detecting cell-cell interactions is a limitation in the analysis of large sets of cell image data, including traditional and combinatorial or high-throughput studies. Here we introduce a novel histogram-based data analysis strategy, termed local cell metrics (LCMs, which addresses this shortcoming. Results The new LCM method is demonstrated via a study of contact inhibition of proliferation of MC3T3-E1 osteoblasts. We describe how LCMs can be used to quantify the local environment of cells and how LCMs are decomposed mathematically into metrics specific to each cell type in a culture, e.g., differently-labelled cells in fluorescence imaging. Using this approach, a quantitative, probabilistic description of the contact inhibition effects in MC3T3-E1 cultures has been achieved. We also show how LCMs are related to the naïve Bayes model. Namely, LCMs are Bayes class-conditional probability functions, suggesting their use for data mining and classification. Conclusion LCMs are successful in robust detection of cell contact inhibition in situations where conventional global statistics fail to do so. The noise due to the random features of cell behavior was suppressed significantly as a result of the focus on local distances, providing sensitive detection of cell-cell contact effects. The methodology can be extended to any quantifiable feature that can be obtained from imaging of cell cultures or tissue samples, including optical, fluorescent, and confocal microscopy. This approach may prove useful in interpreting culture and histological data in fields where cell-cell interactions play a critical

  2. Local cell metrics: a novel method for analysis of cell-cell interactions.

    Science.gov (United States)

    Su, Jing; Zapata, Pedro J; Chen, Chien-Chiang; Meredith, J Carson

    2009-10-23

    The regulation of many cell functions is inherently linked to cell-cell contact interactions. However, effects of contact interactions among adherent cells can be difficult to detect with global summary statistics due to the localized nature and noise inherent to cell-cell interactions. The lack of informatics approaches specific for detecting cell-cell interactions is a limitation in the analysis of large sets of cell image data, including traditional and combinatorial or high-throughput studies. Here we introduce a novel histogram-based data analysis strategy, termed local cell metrics (LCMs), which addresses this shortcoming. The new LCM method is demonstrated via a study of contact inhibition of proliferation of MC3T3-E1 osteoblasts. We describe how LCMs can be used to quantify the local environment of cells and how LCMs are decomposed mathematically into metrics specific to each cell type in a culture, e.g., differently-labelled cells in fluorescence imaging. Using this approach, a quantitative, probabilistic description of the contact inhibition effects in MC3T3-E1 cultures has been achieved. We also show how LCMs are related to the naïve Bayes model. Namely, LCMs are Bayes class-conditional probability functions, suggesting their use for data mining and classification. LCMs are successful in robust detection of cell contact inhibition in situations where conventional global statistics fail to do so. The noise due to the random features of cell behavior was suppressed significantly as a result of the focus on local distances, providing sensitive detection of cell-cell contact effects. The methodology can be extended to any quantifiable feature that can be obtained from imaging of cell cultures or tissue samples, including optical, fluorescent, and confocal microscopy. This approach may prove useful in interpreting culture and histological data in fields where cell-cell interactions play a critical role in determining cell fate, e.g., cancer, developmental

  3. Investigation of integrin expression on the surface of osteoblast-like cells by atomic force microscopy

    International Nuclear Information System (INIS)

    Caneva Soumetz, Federico; Saenz, Jose F.; Pastorino, Laura; Ruggiero, Carmelina; Nosi, Daniele; Raiteri, Roberto

    2010-01-01

    The transforming growth factor β1 (TGF-β1) is a human cytokine which has been demonstrated to modulate cell surface integrin repertoire. In this work integrin expression in response to TGF-β1 stimulation has been investigated on the surface of human osteoblast-like cells. We used atomic force microscopy (AFM) and confocal laser scanning microscopy to assess integrin expression and to evaluate their distribution over the dorsal side of the plasma membrane. AFM probes have been covalently functionalised with monoclonal antibodies specific to the β1 integrin subunit. Force curves have been collected in order to obtain maps of the interaction between the immobilized antibody and the respective cell membrane receptors. Adhesion peaks have been automatically detected by means of an ad hoc developed data analysis software. The specificity of the detected interactions has been assessed by adding free antibody in the solution and monitoring the dramatic decrease in the recorded interactions. In addition, the effect of TGF-β1 treatment on both the fluorescence signal and the adhesion events has been tested. The level of expression of the β1 integrin subunit was enhanced by TGF-β1. As a further analysis, the adhesion force of the single living cells to the substrate was measured by laterally pushing the cell with the AFM tip and measuring the force necessary to displace it. The treatment with TGF-β1 resulted in a decrease of the cell/substrate adhesion force. Results obtained by AFM have been validated by confocal laser scanning microscopy thus demonstrating the high potential of the AFM technique for the investigation of cell surface receptors distribution and trafficking at the nanoscale.

  4. Investigation of integrin expression on the surface of osteoblast-like cells by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Caneva Soumetz, Federico [Department of Communication, Computer and System Sciences, University of Genova, Via Opera Pia, 13-16145 Genova (Italy); Saenz, Jose F. [Biophysical and Electronic Engineering Department, University of Genova, Via All' Opera Pia 11a, 16145 Genova (Italy); Pastorino, Laura; Ruggiero, Carmelina [Department of Communication, Computer and System Sciences, University of Genova, Via Opera Pia, 13-16145 Genova (Italy); Nosi, Daniele [Department of Anatomy, Histology and Forensic Medicine, Bio-photonic Laboratory, University of Florence, viale Morgagni, 85 Firenze, CAP 50134 Florence (Italy); Raiteri, Roberto, E-mail: rr@unige.it [Biophysical and Electronic Engineering Department, University of Genova, Via All' Opera Pia 11a, 16145 Genova (Italy)

    2010-03-15

    The transforming growth factor {beta}1 (TGF-{beta}1) is a human cytokine which has been demonstrated to modulate cell surface integrin repertoire. In this work integrin expression in response to TGF-{beta}1 stimulation has been investigated on the surface of human osteoblast-like cells. We used atomic force microscopy (AFM) and confocal laser scanning microscopy to assess integrin expression and to evaluate their distribution over the dorsal side of the plasma membrane. AFM probes have been covalently functionalised with monoclonal antibodies specific to the {beta}1 integrin subunit. Force curves have been collected in order to obtain maps of the interaction between the immobilized antibody and the respective cell membrane receptors. Adhesion peaks have been automatically detected by means of an ad hoc developed data analysis software. The specificity of the detected interactions has been assessed by adding free antibody in the solution and monitoring the dramatic decrease in the recorded interactions. In addition, the effect of TGF-{beta}1 treatment on both the fluorescence signal and the adhesion events has been tested. The level of expression of the {beta}1 integrin subunit was enhanced by TGF-{beta}1. As a further analysis, the adhesion force of the single living cells to the substrate was measured by laterally pushing the cell with the AFM tip and measuring the force necessary to displace it. The treatment with TGF-{beta}1 resulted in a decrease of the cell/substrate adhesion force. Results obtained by AFM have been validated by confocal laser scanning microscopy thus demonstrating the high potential of the AFM technique for the investigation of cell surface receptors distribution and trafficking at the nanoscale.

  5. Platelet-tumor cell interaction with the subendothelial extracellular matrix: relationship to cancer metastasis

    Energy Technology Data Exchange (ETDEWEB)

    Yahalom, J; Biran, S; Fuks, Z; Vlodavsky, I [Hadassah University Hospital, Jerusalem (Israel). Dept. of Radiation and Clinical Oncology; Eldor, A [Hadassah University Hospital, Jerusalem (Israel). Dept. of Hematology

    1985-04-01

    Dissemination of neoplastic cells within the body involves invasion of blood vessels by tumor cells. This requires adhesion of blood-borne cells to the luminal surface of the vascular endothelium, invasion through the endothelial cell layer and local dissolution of the subendothelial basement membrane. The authors studied the interaction of platelets and tumor cells with cultured vascular endothelial cells and their secreted basement membrane-like extracellular matrix (ECM). Interaction of platelets with this ECM was associated with platelet activation, aggregation and degradation of heparan sulfate in the ECM by means of the platelet heparitinase. Biochemical and scanning electron microscopy (SEM) studies have demonstrated that platelets may detect even minor gaps between adjacent endothelial cells and degrade the ECM heparan sulfate. Platelets were also shown to recruit lymphoma cells into minor gaps in the vascular endothelium. It is suggested that the platelet heparitinase is involved in the impairment of the integrity of the vessel wall and thus play a role in tumor cell metastasis.

  6. Magnetization of individual yeast cells by in situ formation of iron oxide on cell surfaces

    Science.gov (United States)

    Choi, Jinsu; Lee, Hojae; Choi, Insung S.; Yang, Sung Ho

    2017-09-01

    Magnetic functionalization of living cells has intensively been investigated with the aim of various bioapplications such as selective separation, targeting, and localization of the cells by using an external magnetic field. However, the magnetism has not been introduced to individual living cells through the in situ chemical reactions because of harsh conditions required for synthesis of magnetic materials. In this work, magnetic iron oxide was formed on the surface of living cells by optimizing reactions conditions to be mild sufficiently enough to sustain cell viability. Specifically, the reactive LbL strategy led to formation of magnetically responsive yeast cells with iron oxide shells. This facile and direct post-magnetization method would be a useful tool for remote manipulation of living cells with magnetic interactions, which is an important technique for the integration of cell-based circuits and the isolation of cell in microfluidic devices.

  7. VIGO: Instrumental Interaction in Multi-Surface Environments

    DEFF Research Database (Denmark)

    Klokmose, Clemens Nylandsted; Beaudouin-Lafon, Michel

    2009-01-01

    This paper addresses interaction in multi-surface environments and questions whether the current application-centric approaches to user interfaces are adequate in this context, and presents an alternative approach based on instrumental interaction. The paper presents the VIGO (Views, Instruments...

  8. Organic chemistry on Titan: Surface interactions

    Science.gov (United States)

    Thompson, W. Reid; Sagan, Carl

    1992-01-01

    The interaction of Titan's organic sediments with the surface (solubility in nonpolar fluids) is discussed. How Titan's sediments can be exposed to an aqueous medium for short, but perhaps significant, periods of time is also discussed. Interactions with hydrocarbons and with volcanic magmas are considered. The alteration of Titan's organic sediments over geologic time by the impacts of meteorites and comets is discussed.

  9. Cell behaviour on chemically microstructured surfaces

    International Nuclear Information System (INIS)

    Magnani, Agnese; Priamo, Alfredo; Pasqui, Daniela; Barbucci, Rolando

    2003-01-01

    Micropatterned surfaces with different chemical topographies were synthesised in order to investigate the influence of surface chemistry and topography on cell behaviour. The microstructured materials were synthesised by photoimmobilising natural Hyaluronan (Hyal) and its sulphated derivative (HyalS), both adequately functionalised with a photorective moiety, on glass substrates. Four different grating patterns (10, 25, 50 and 100 μm) were used to pattern the hyaluronan. The micropatterned samples were analysed by Secondary Ions Mass Spectrometry, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy to investigate the chemistry and the topography of the surfaces. The spectroscopic and microscopic analysis of the microstructured surfaces revealed that the photoimmobilisation process was successful, demonstrating that the photomask patterns were well reproduced on the sample surface. The influence of chemical topographies on the cell behaviour was then analysed. Human and 3T3 fibroblasts, bovine aortic and human (HGTFN line) endothelial cells were used and their behaviour on the micropatterned surfaces was analysed in terms of adhesion, proliferation, locomotion and orientation. Both chemical and topographical controls were found to be important for cell guidance. By decreasing the stripe dimensions, a more fusiform shape of cell was observed. At the same time, the cell locomotion and orientation parallel to the structure increased. However, differences in cell behaviour were detected according to both cell type and micropattern dimensions

  10. The neuronal Ca(2+) -binding protein 2 (NECAB2) interacts with the adenosine A(2A) receptor and modulates the cell surface expression and function of the receptor.

    Science.gov (United States)

    Canela, Laia; Luján, Rafael; Lluís, Carme; Burgueño, Javier; Mallol, Josefa; Canela, Enric I; Franco, Rafael; Ciruela, Francisco

    2007-09-01

    Heptaspanning membrane also known as G protein-coupled receptors (GPCR) do interact with a variety of intracellular proteins whose function is regulate receptor traffic and/or signaling. Using a yeast two-hybrid screen, NECAB2, a neuronal calcium binding protein, was identified as a binding partner for the adenosine A(2A) receptor (A(2A)R) interacting with its C-terminal domain. Co-localization, co-immunoprecipitation and pull-down experiments showed a close and specific interaction between A(2A)R and NECAB2 in both transfected HEK-293 cells and also in rat striatum. Immunoelectron microscopy detection of NECAB2 and A(2A)R in the rat striatopallidal structures indicated that both proteins are co-distributed in the same glutamatergic nerve terminals. The interaction of NECAB2 with A(2A)R modulated the cell surface expression, the ligand-dependent internalization and the receptor-mediated activation of the MAPK pathway. Overall, these results show that A(2A)R interacts with NECAB2 in striatal neurones co-expressing the two proteins and that the interaction is relevant for A(2A)R function.

  11. Monitoring peptide-surface interaction by means of molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Nonella, Marco, E-mail: mnonella@pci.uzh.ch [Physikalisch-Chemisches Institut, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland); Seeger, Stefan, E-mail: sseeger@pci.uzh.ch [Physikalisch-Chemisches Institut, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland)

    2010-12-09

    Graphical abstract: Protein-surface interactions play a crucial role in a wide field of research areas like biology, biotechnology, or pharmacology. Only recently, it has been shown that not only peptide adsorption represents an important process but also spreading and clustering of adsorbed proteins. By means of classical molecular dynamics, peptide adsorption as well as the dynamics of adsorbed peptides have been investigated in order to gain deeper insight into such processes. The picture shows a snapshot of an adsorbed peptide on a silica surface showing strong direct hydrogen bonding. Research highlights: {yields} Simulation of peptide surface interaction. {yields} Dynamics of hydrogen bond formation and destruction. {yields} Internal flexibility of adsorbed peptides. - Abstract: Protein adsorption and protein surface interactions have become an important research topic in recent years. Very recently, for example, it has been shown that protein clusters can undergo a surface-induced spreading after adsorption. Such phenomena emphasize the need of a more detailed insight into protein-silica interaction at an atomic level. Therefore, we have studied a model system consisting of a short peptide, a silica slab, and water molecules by means of classical molecular dynamics simulations. The study reveals that, besides of electrostatic interactions caused by the chosen charge distribution, the peptide interacts with the silica surface through formation of direct peptide-surface hydrogen bonds as well as indirect peptide-water-surface hydrogen bonds. The number of created hydrogen bonds varies considerably among the simulated structures. The strength of hydrogen bonding determines the mobility of the peptide on the surface and the internal flexibility of the adsorbed peptide.

  12. Linear response theory of activated surface diffusion with interacting adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Marti' nez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Sanz, A.S.; Vega, J.L. [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rojas-Lorenzo, G. [Instituto Superior de Tecnologi' as y Ciencias Aplicadas, Ave. Salvador Allende, esq. Luaces, 10400 La Habana (Cuba); Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain); Miret-Artes, S., E-mail: s.miret@imaff.cfmac.csic.es [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain)

    2010-05-12

    Graphical abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed. - Abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.

  13. Bio-Orthogonal Mediated Nucleic Acid Transfection of Cells via Cell Surface Engineering.

    Science.gov (United States)

    O'Brien, Paul J; Elahipanah, Sina; Rogozhnikov, Dmitry; Yousaf, Muhammad N

    2017-05-24

    The efficient delivery of foreign nucleic acids (transfection) into cells is a critical tool for fundamental biomedical research and a pillar of several biotechnology industries. There are currently three main strategies for transfection including reagent, instrument, and viral based methods. Each technology has significantly advanced cell transfection; however, reagent based methods have captured the majority of the transfection market due to their relatively low cost and ease of use. This general method relies on the efficient packaging of a reagent with nucleic acids to form a stable complex that is subsequently associated and delivered to cells via nonspecific electrostatic targeting. Reagent transfection methods generally use various polyamine cationic type molecules to condense with negatively charged nucleic acids into a highly positively charged complex, which is subsequently delivered to negatively charged cells in culture for association, internalization, release, and expression. Although this appears to be a straightforward procedure, there are several major issues including toxicity, low efficiency, sorting of viable transfected from nontransfected cells, and limited scope of transfectable cell types. Herein, we report a new strategy (SnapFect) for nucleic acid transfection to cells that does not rely on electrostatic interactions but instead uses an integrated approach combining bio-orthogonal liposome fusion, click chemistry, and cell surface engineering. We show that a target cell population is rapidly and efficiently engineered to present a bio-orthogonal functional group on its cell surface through nanoparticle liposome delivery and fusion. A complementary bio-orthogonal nucleic acid complex is then formed and delivered to which chemoselective click chemistry induced transfection occurs to the primed cell. This new strategy requires minimal time, steps, and reagents and leads to superior transfection results for a broad range of cell types

  14. Adhesive interaction measured between AFM probe and lung epithelial type II cells

    International Nuclear Information System (INIS)

    Leonenko, Zoya; Finot, Eric; Amrein, Matthias

    2007-01-01

    The toxicity of inhaled nanoparticles entering the body through the lung is thought to be initially defined by the electrostatic and adhesive interaction of the particles with lung's wall. Here, we investigated the first step of the interaction of nanoparticles with lung epithelial cells using atomic force microscope (AFM) as a force apparatus. Nanoparticles were modeled by the apex of the AFM tip and the forces of interaction between the tip and the cell analyzed over time. The adhesive force and work of adhesion strongly increased for the first 100 s of contact and then leveled out. During this time, the tip was penetrating deeply into the cell. It first crossed a stiff region of the cell and then entered a much more compliant cell region. The work of adhesion and its progression over time were not dependent on the load with which the tip was brought into contact with the cell. We conclude that the initial thermodynamic aspects and the time course of the uptake of nanoparticles by lung epithelial cells can be studied using our experimental approach. It is discussed how the potential health threat posed by nanoparticles of different size and surface characteristics can be evaluated using the method presented

  15. In-cell thermodynamics and a new role for protein surfaces.

    Science.gov (United States)

    Smith, Austin E; Zhou, Larry Z; Gorensek, Annelise H; Senske, Michael; Pielak, Gary J

    2016-02-16

    There is abundant, physiologically relevant knowledge about protein cores; they are hydrophobic, exquisitely well packed, and nearly all hydrogen bonds are satisfied. An equivalent understanding of protein surfaces has remained elusive because proteins are almost exclusively studied in vitro in simple aqueous solutions. Here, we establish the essential physiological roles played by protein surfaces by measuring the equilibrium thermodynamics and kinetics of protein folding in the complex environment of living Escherichia coli cells, and under physiologically relevant in vitro conditions. Fluorine NMR data on the 7-kDa globular N-terminal SH3 domain of Drosophila signal transduction protein drk (SH3) show that charge-charge interactions are fundamental to protein stability and folding kinetics in cells. Our results contradict predictions from accepted theories of macromolecular crowding and show that cosolutes commonly used to mimic the cellular interior do not yield physiologically relevant information. As such, we provide the foundation for a complete picture of protein chemistry in cells.

  16. Micro- and nanostructured Al{sub 2}O{sub 3} surfaces for controlled vascular endothelial and smooth muscle cell adhesion and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Aktas, Cenk, E-mail: cenk.aktas@inm-gmbh.de [INM - Leibniz Institute for New Materials, CVD/Biosurfaces Division, 66123 Saarbruecken (Germany); Doerrschuck, Eva; Schuh, Cathrin [Clinic of Paediatric Cardiology, Saarland University, Building 9, 66424 Homburg (Germany); Miro, Marina Martinez; Lee, Juseok [INM - Leibniz Institute for New Materials, CVD/Biosurfaces Division, 66123 Saarbruecken (Germany); Puetz, Norbert; Wennemuth, Gunther [Department of Anatomy and Cell Biology, Saarland University, Building 61, 66424 Homburg (Germany); Metzger, Wolfgang; Oberringer, Martin [Department of Trauma-, Hand- and Reconstructive Surgery, Saarland University, Building 57, 66424 Homburg (Germany); Veith, Michael [INM - Leibniz Institute for New Materials, CVD/Biosurfaces Division, 66123 Saarbruecken (Germany); Department of Inorganic Chemistry, University of Saarland, Building C 4 1, 66123 Saarbruecken (Germany); Abdul-Khaliq, Hashim [Clinic of Paediatric Cardiology, Saarland University, Building 9, 66424 Homburg (Germany)

    2012-07-01

    The effect of the micro- and nanotopography on vascular cell-surface interaction is investigated using nano- and microstructured Al{sub 2}O{sub 3} as model substrate. Two different nanostructured Al{sub 2}O{sub 3} surfaces composed of low density (LD) and high density (HD) nanowires (NWs) were synthesized by chemical vapour deposition (CVD) and commercially available microstructured Al{sub 2}O{sub 3} plates were used for comparison. A clear diverging response of human umbilical vein endothelial cells (HUVEC) and human umbilical vein smooth muscle cells (HUVSMC) was observed on these nano- and microstructured surfaces. LD Al{sub 2}O{sub 3} NWs seem to enhance the proliferation of HUVECs selectively. This selective control of the cell-surface interaction by topography may represent a key issue for the future stent material design. - Highlights: Black-Right-Pointing-Pointer Nanostructured alumina surfaces triggers selective adhesion and proliferation of endothelial cells. Black-Right-Pointing-Pointer Catalyst free synthesis of nanowires. Black-Right-Pointing-Pointer Topography induces selective cell response.

  17. SU-F-SPS-08: Measuring the Interaction Of DDR Cell Receptors and Extracellular Matrix Collagen in Prostate Cells

    Energy Technology Data Exchange (ETDEWEB)

    Dong, J; Sarkar, A; Hoffmann, P [Wayne State University, Detroit, MI (United States); Suhail, A; Fridman, R [Wayne State University School of Medicine, Detroit, MI (United States)

    2016-06-15

    Purpose: Discoidin domain receptors (DDR) have recently been recognized as important players in cancer progression. DDRs are cell receptors that interact with collagen, an extracellular matrix (ECM) protein. However the detailed mechanism of their interaction is unclear. Here we attempted to examine their interaction in terms of structural (surface topography), mechanical (rupture force), and kinetic (binding probability) information on the single molecular scale with the use of atomic force microscopy (AFM). Methods: The Quantitative Nano-mechanical property Mapping (QNM) mode of AFM allowed to assess the cells in liquid growth media at their optimal physiological while being viable. Human benign prostate hyperplasia (BPH-1) cell line was genetically regulated to suppress DDR expression (DDR- cells) and was compared with naturally DDR expressing cells (DDR+). Results: Binding force measurements (n = 1000) were obtained before and after the two groups were treated with fibronectin (FN), an integrin-inhibiting antibody to block the binding of integrin. The quantification indicates that cells containing DDR bind with collagen at a most probable force of 80.3–83.0 ±7.6 pN. The probability of them binding is 0.167 when other interactions (mainly due to integrin-collagen binding) are minimized. Conclusion: Together with further force measurements at different pulling speeds will determine dissociation rate, binding distance and activation barrier. These parameters in benign cells provides some groundwork in understanding DDR’s behavior in various cell microenvironments such as in malignant tumor cells. Funding supported by Richard Barber Interdisciplinary Research Program of Wayne State University.

  18. SU-F-SPS-08: Measuring the Interaction Of DDR Cell Receptors and Extracellular Matrix Collagen in Prostate Cells

    International Nuclear Information System (INIS)

    Dong, J; Sarkar, A; Hoffmann, P; Suhail, A; Fridman, R

    2016-01-01

    Purpose: Discoidin domain receptors (DDR) have recently been recognized as important players in cancer progression. DDRs are cell receptors that interact with collagen, an extracellular matrix (ECM) protein. However the detailed mechanism of their interaction is unclear. Here we attempted to examine their interaction in terms of structural (surface topography), mechanical (rupture force), and kinetic (binding probability) information on the single molecular scale with the use of atomic force microscopy (AFM). Methods: The Quantitative Nano-mechanical property Mapping (QNM) mode of AFM allowed to assess the cells in liquid growth media at their optimal physiological while being viable. Human benign prostate hyperplasia (BPH-1) cell line was genetically regulated to suppress DDR expression (DDR- cells) and was compared with naturally DDR expressing cells (DDR+). Results: Binding force measurements (n = 1000) were obtained before and after the two groups were treated with fibronectin (FN), an integrin-inhibiting antibody to block the binding of integrin. The quantification indicates that cells containing DDR bind with collagen at a most probable force of 80.3–83.0 ±7.6 pN. The probability of them binding is 0.167 when other interactions (mainly due to integrin-collagen binding) are minimized. Conclusion: Together with further force measurements at different pulling speeds will determine dissociation rate, binding distance and activation barrier. These parameters in benign cells provides some groundwork in understanding DDR’s behavior in various cell microenvironments such as in malignant tumor cells. Funding supported by Richard Barber Interdisciplinary Research Program of Wayne State University

  19. Human mast cell and airway smooth muscle cell interactions: implications for asthma.

    Science.gov (United States)

    Page, S; Ammit, A J; Black, J L; Armour, C L

    2001-12-01

    Asthma is characterized by inflammation, hyperresponsiveness, and remodeling of the airway. Human mast cells (HMCs) play a central role in all of these changes by releasing mediators that cause exaggerated bronchoconstriction, induce human airway smooth muscle (HASM) cell proliferation, and recruit and activate inflammatory cells. Moreover, the number of HMCs present on asthmatic HASM is increased compared with that on nonasthmatic HASM. HASM cells also have the potential to actively participate in the inflammatory process by synthesizing cytokines and chemokines and expressing surface molecules, which have the capacity to perpetuate the inflammatory mechanisms present in asthma. This review specifically examines how the mediators of HMCs have the capacity to modulate many functions of HASM; how the synthetic function of HASM, particularly through the release and expression of stem cell factor, has the potential to influence HMC number and activation in an extraordinarily potent and proinflammatory manner; and how these interactions between HMCs and HASM have potential consequences for airway structure and inflammation relevant to the disease process of asthma.

  20. Hsc70 regulates cell surface ASIC2 expression and vascular smooth muscle cell migration.

    Science.gov (United States)

    Grifoni, Samira C; McKey, Susan E; Drummond, Heather A

    2008-05-01

    Recent studies suggest members of the degenerin (DEG)/epithelial Na(+) channel (ENaC)/acid-sensing ion channel (ASIC) protein family play an important role in vascular smooth muscle cell (VSMC) migration. In a previous investigation, we found suppression of a certain DEG/ENaC/ASIC member, ASIC2, increased VSMC chemotactic migration, raising the possibility that ASIC2 may play an inhibitory role. Because ASIC2 protein was retained in the cytoplasm, we reasoned increasing surface expression of ASIC2 might unmask the inhibitory role of ASIC2 in VSMC migration so we could test the hypothesis that ASIC2 inhibits VSMC migration. Therefore, we used the chemical chaperone glycerol to enhance ASIC2 expression. Glycerol 1) increased cytoplasm ASIC2 expression, 2) permitted detection of ASIC2 at the cell surface, and 3) inhibited platelet-derived growth factor (PDGF)-bb mediated VSMC migration. Furthermore, ASIC2 silencing completely abolished the inhibitory effect of glycerol on migration, suggesting upregulation of ASIC2 is responsible for glycerol-induced inhibition of VSMC migration. Because other investigators have shown that glycerol regulates ENaC/ASIC via interactions with a certain heat shock protein, heat shock protein 70 (Hsc70), we wanted to determine the importance of Hsc70 on ASIC2 expression in VSMCs. We found that Hsc70 silencing increases ASIC2 cell surface expression and inhibits VSMC migration, which is abolished by cosilencing ASIC2. These data demonstrate that Hsc70 inhibits ASIC2 expression, and, when the inhibitory effect of Hsc70 is removed, ASIC2 expression increases, resulting in reduced VSMC migration. Because VSMC migration contributes to vasculogenesis and remodeling following vascular injury, our findings raise the possibility that ASIC2-Hsc70 interactions may play a role in these processes.

  1. A cell-surface-anchored ratiometric i-motif sensor for extracellular pH detection.

    Science.gov (United States)

    Ying, Le; Xie, Nuli; Yang, Yanjing; Yang, Xiaohai; Zhou, Qifeng; Yin, Bincheng; Huang, Jin; Wang, Kemin

    2016-06-14

    A FRET-based sensor is anchored on the cell surface through streptavidin-biotin interactions. Due to the excellent properties of the pH-sensitive i-motif structure, the sensor can detect extracellular pH with high sensitivity and excellent reversibility.

  2. Cell-biomaterial mechanical interaction in the framework of tissue engineering: insights, computational modeling and perspectives.

    Science.gov (United States)

    Sanz-Herrera, Jose A; Reina-Romo, Esther

    2011-01-01

    Tissue engineering is an emerging field of research which combines the use of cell-seeded biomaterials both in vitro and/or in vivo with the aim of promoting new tissue formation or regeneration. In this context, how cells colonize and interact with the biomaterial is critical in order to get a functional tissue engineering product. Cell-biomaterial interaction is referred to here as the phenomenon involved in adherent cells attachment to the biomaterial surface, and their related cell functions such as growth, differentiation, migration or apoptosis. This process is inherently complex in nature involving many physico-chemical events which take place at different scales ranging from molecular to cell body (organelle) levels. Moreover, it has been demonstrated that the mechanical environment at the cell-biomaterial location may play an important role in the subsequent cell function, which remains to be elucidated. In this paper, the state-of-the-art research in the physics and mechanics of cell-biomaterial interaction is reviewed with an emphasis on focal adhesions. The paper is focused on the different models developed at different scales available to simulate certain features of cell-biomaterial interaction. A proper understanding of cell-biomaterial interaction, as well as the development of predictive models in this sense, may add some light in tissue engineering and regenerative medicine fields.

  3. Stochastic Description of Activated Surface Diffusion with Interacting Adsorbates

    Science.gov (United States)

    Martínez-Casado, Ruth; Vega, José Luis; Sanz, Ángel S.; Miret-Artés, Salvador

    Activated surface diffusion on metal surfaces is receiving much attention both experimentally and theoretically. One of the main theoretical problems in this field is to explain the line-shape broadening observed when the surface coverage is increased. Recently, we have proposed a fully stochastic model, the interacting single adsorbate (ISA) model, aimed at explaining and understanding this type of experiments, which essentially consists of considering the classical Langevin formulation with two types of noise forces: (i) a Gaussian white noise accounting for the substrate friction, and (ii) a shot noise simulating the interacting adsorbates at different coverages. No interaction potential between adsorbates is included because any trace of microscopic interaction seems to be wiped out in a Markovian regime. This model describes in a good approximation, and at a very low computational cost, the line-shape broadening observed experimentally. Furthermore, its mathematical simplicity also allows to derive some analytical expressions which are of much help in the interpretation of the physics underlying surface diffusion processes.

  4. Interactions between bone cells and biomaterials: An update.

    Science.gov (United States)

    Beauvais, Sabrina; Drevelle, Olivier; Jann, Jessica; Lauzon, Marc-Antoine; Foruzanmehr, Mohammadreza; Grenier, Guillaume; Roux, Sophie; Faucheux, Nathalie

    2016-06-01

    As the populations of the Western world become older, they will suffer more and more from bone defects related to osteoporosis (non-union fractures, vertebral damages), cancers (malignant osteolysis) and infections (osteomyelitis). Autografts are usually used to fill these defects, but they have several drawbacks such as morbidity at the donor site and the amount and quality of bone that can be harvested. Recent scientific milestones made in biomaterials development were shown to be promising to overcome these limitations. Cell interactions with biomaterials can be improved by adding at their surface functional groups such as adhesive peptides and/or growth factors. The development of such biomimetic materials able to control bone cell responses can only proceed if it is based on a sound understanding of bone cell behavior and regulation. This review focuses on bone physiology and the regulation of bone cell differentiation and function, and how the latest advances in biomimetic materials can be translated within promising clinical outcomes.

  5. Localized Modeling of Biochemical and Flow Interactions during Cancer Cell Adhesion.

    Directory of Open Access Journals (Sweden)

    Julie Behr

    Full Text Available This work focuses on one component of a larger research effort to develop a simulation tool to model populations of flowing cells. Specifically, in this study a local model of the biochemical interactions between circulating melanoma tumor cells (TC and substrate adherent polymorphonuclear neutrophils (PMN is developed. This model provides realistic three-dimensional distributions of bond formation and attendant attraction and repulsion forces that are consistent with the time dependent Computational Fluid Dynamics (CFD framework of the full system model which accounts local pressure, shear and repulsion forces. The resulting full dynamics model enables exploration of TC adhesion to adherent PMNs, which is a known participating mechanism in melanoma cell metastasis. The model defines the adhesion molecules present on the TC and PMN cell surfaces, and calculates their interactions as the melanoma cell flows past the PMN. Biochemical rates of reactions between individual molecules are determined based on their local properties. The melanoma cell in the model expresses ICAM-1 molecules on its surface, and the PMN expresses the β-2 integrins LFA-1 and Mac-1. In this work the PMN is fixed to the substrate and is assumed fully rigid and of a prescribed shear-rate dependent shape obtained from micro-PIV experiments. The melanoma cell is transported with full six-degrees-of-freedom dynamics. Adhesion models, which represent the ability of molecules to bond and adhere the cells to each other, and repulsion models, which represent the various physical mechanisms of cellular repulsion, are incorporated with the CFD solver. All models are general enough to allow for future extensions, including arbitrary adhesion molecule types, and the ability to redefine the values of parameters to represent various cell types. The model presented in this study will be part of a clinical tool for development of personalized medical treatment programs.

  6. Localized Modeling of Biochemical and Flow Interactions during Cancer Cell Adhesion.

    Science.gov (United States)

    Behr, Julie; Gaskin, Byron; Fu, Changliang; Dong, Cheng; Kunz, Robert

    2015-01-01

    This work focuses on one component of a larger research effort to develop a simulation tool to model populations of flowing cells. Specifically, in this study a local model of the biochemical interactions between circulating melanoma tumor cells (TC) and substrate adherent polymorphonuclear neutrophils (PMN) is developed. This model provides realistic three-dimensional distributions of bond formation and attendant attraction and repulsion forces that are consistent with the time dependent Computational Fluid Dynamics (CFD) framework of the full system model which accounts local pressure, shear and repulsion forces. The resulting full dynamics model enables exploration of TC adhesion to adherent PMNs, which is a known participating mechanism in melanoma cell metastasis. The model defines the adhesion molecules present on the TC and PMN cell surfaces, and calculates their interactions as the melanoma cell flows past the PMN. Biochemical rates of reactions between individual molecules are determined based on their local properties. The melanoma cell in the model expresses ICAM-1 molecules on its surface, and the PMN expresses the β-2 integrins LFA-1 and Mac-1. In this work the PMN is fixed to the substrate and is assumed fully rigid and of a prescribed shear-rate dependent shape obtained from micro-PIV experiments. The melanoma cell is transported with full six-degrees-of-freedom dynamics. Adhesion models, which represent the ability of molecules to bond and adhere the cells to each other, and repulsion models, which represent the various physical mechanisms of cellular repulsion, are incorporated with the CFD solver. All models are general enough to allow for future extensions, including arbitrary adhesion molecule types, and the ability to redefine the values of parameters to represent various cell types. The model presented in this study will be part of a clinical tool for development of personalized medical treatment programs.

  7. Designed Surface Topographies Control ICAM-1 Expression in Tonsil-Derived Human Stromal Cells

    Directory of Open Access Journals (Sweden)

    Aliaksei S. Vasilevich

    2018-06-01

    Full Text Available Fibroblastic reticular cells (FRCs, the T-cell zone stromal cell subtype in the lymph nodes, create a scaffold for adhesion and migration of immune cells, thus allowing them to communicate. Although known to be important for the initiation of immune responses, studies about FRCs and their interactions have been impeded because FRCs are limited in availability and lose their function upon culture expansion. To circumvent these limitations, stromal cell precursors can be mechanotranduced to form mature FRCs. Here, we used a library of designed surface topographies to trigger FRC differentiation from tonsil-derived stromal cells (TSCs. Undifferentiated TSCs were seeded on a TopoChip containing 2176 different topographies in culture medium without differentiation factors, then monitored cell morphology and the levels of ICAM-1, a marker of FRC differentiation. We identified 112 and 72 surfaces that upregulated and downregulated, respectively, ICAM-1 expression. By monitoring cell morphology, and expression of the FRC differentiation marker ICAM-1 via image analysis and machine learning, we discovered correlations between ICAM-1 expression, cell shape and design of surface topographies and confirmed our findings by using flow cytometry. Our findings confirmed that TSCs are mechano-responsive cells and identified particular topographies that can be used to improve FRC differentiation protocols.

  8. Nucleolin: acharan sulfate–binding protein on the surface of cancer cells

    Science.gov (United States)

    Joo, Eun Ji; ten Dam, Gerdy B.; van Kuppevelt, Toin H.; Toida, Toshihiko; Linhardt, Robert J.; Kim, Yeong Shik

    2005-01-01

    Glycosaminoglycans (GAGs) are complex polysaccharides that participate in the regulation of physiological processes through the interactions with a wide variety of proteins. Acharan sulfate (AS), isolated from the giant African snail Achatina fulica, primarily consists of the repeating disaccharide structure α-D-N-acetylglucosaminyl (1→4) 2-sulfoiduronic acid. Exogenous AS was injected subcutaneously near the tumor tissue in C57BL/6 mice that had been implanted with Lewis lung carcinoma cells (LLCs). The location of AS in the tumor was assessed by staining of sectioned tissues with alcian blue and periodic acid–Schiff (PAS) reagent. In vitro assays indicated binding of cells to 50 μg/ml AS (or heparin) after a 5-h incubation. Immunofluorescence assays, using anti-AS antibody, detected AS at the cell surface. The outer-surface of LLCs were next biotinylated to identify the AS-binding proteins. Biotinylated cells were lysed, and the lysates were fractionated on the AS affinity column using a stepwise salt gradient (0, 0.1, 0.3, 0.5, 0.7, 1.0, and 2.0 M). The fractions were analyzed by SDS–PAGE with silver staining and western blotting. We focused on the proteins with high affinity for AS (eluting at 1 M NaCl) and detected only two bands by western blotting. ESI Q-TOF MS analysis of one of these bands, molecular weight ~110 kDa, showed it to be nucleolin. A phosphorylated form of nucleolin on the surface of cells acts as a cell surface receptor for a variety of ligands, including growth factors (i.e., basic fibroblast growth factor) and chemokines (i.e., midkine). These results show that nucleolin is one of several AS-binding proteins and suggest that AS might demonstrate its tumor growth inhibitory activity by binding the nucleolin receptor protein on the surface of cancer cells. PMID:15329357

  9. Electroreflectance and the problem of studying plasma-surface interactions

    International Nuclear Information System (INIS)

    Preppernau, B.L.

    1995-01-01

    A long standing problem in low-temperature plasma discharge physics is to understand in detail the mutual interaction of real exposed surfaces (electrodes) with the reactive plasma environment. In particular, one wishes to discern the influence of these surfaces on the plasma parameters given their contributions from secondary electrons and ions. This paper briefly reviews the known surface interaction processes as well as currently available diagnostics to study the interface between plasmas and surfaces. Next comes a discussion describing the application of plasma-modulated electroreflectance to this research and some potential experimental techniques

  10. Glial cell adhesion and protein adsorption on SAM coated semiconductor and glass surfaces of a microfluidic structure

    Science.gov (United States)

    Sasaki, Darryl Y.; Cox, Jimmy D.; Follstaedt, Susan C.; Curry, Mark S.; Skirboll, Steven K.; Gourley, Paul L.

    2001-05-01

    The development of microsystems that merge biological materials with microfabricated structures is highly dependent on the successful interfacial interactions between these innately incompatible materials. Surface passivation of semiconductor and glass surfaces with thin organic films can attenuate the adhesion of proteins and cells that lead to biofilm formation and biofouling of fluidic structures. We have examined the adhesion of glial cells and serum albumin proteins to microfabricated glass and semiconductor surfaces coated with self-assembled monolayers of octadecyltrimethoxysilane and N-(triethoxysilylpropyl)-O- polyethylene oxide urethane, to evaluate the biocompatibility and surface passivation those coatings provide.

  11. Secret handshakes: cell-cell interactions and cellular mimics.

    Science.gov (United States)

    Cohen, Daniel J; Nelson, W James

    2018-02-01

    Cell-cell junctions, acting as 'secret handshakes', mediate cell-cell interactions and make multicellularity possible. Work over the previous century illuminated key players comprising these junctions including the cadherin superfamily, nectins, CAMs, connexins, notch/delta, lectins, and eph/Ephrins. Recent work has focused on elucidating how interactions between these complex and often contradictory cues can ultimately give rise to large-scale organization in tissues. This effort, in turn, has enabled bioengineering advances such as cell-mimetic interfaces that allow us to better probe junction biology and to develop new biomaterials. This review details exciting, recent developments in these areas as well as providing both historical context and a discussion of some topical challenges and opportunities for the future. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Interaction of Stellate Cells with Pancreatic Carcinoma Cells

    Directory of Open Access Journals (Sweden)

    Marco Siech

    2010-09-01

    Full Text Available Pancreatic cancer is characterized by its late detection, aggressive growth, intense infiltration into adjacent tissue, early metastasis, resistance to chemo- and radiotherapy and a strong “desmoplastic reaction”. The dense stroma surrounding carcinoma cells is composed of fibroblasts, activated stellate cells (myofibroblast-like cells, various inflammatory cells, proliferating vascular structures, collagens and fibronectin. In particular the cellular components of the stroma produce the tumor microenvironment, which plays a critical role in tumor growth, invasion, spreading, metastasis, angiogenesis, inhibition of anoikis, and chemoresistance. Fibroblasts, myofibroblasts and activated stellate cells produce the extracellular matrix components and are thought to interact actively with tumor cells, thereby promoting cancer progression. In this review, we discuss our current understanding of the role of pancreatic stellate cells (PSC in the desmoplastic response of pancreas cancer and the effects of PSC on tumor progression, metastasis and drug resistance. Finally we present some novel ideas for tumor therapy by interfering with the cancer cell-host interaction.

  13. Interactions of planetary magnetospheres with icy satellite surfaces

    International Nuclear Information System (INIS)

    Cheng, A.F.; Haff, P.K.; Johnson, R.E.; Lanzerotti, L.J.

    1986-01-01

    When natural satellites and ring particles are embedded within magnetospheric plasmas, the charged particles interact with the surfaces of these solid bodies. These interactions have important implications for the surface, the atmosphere of the parent body, and the magnetosphere as a whole. Significant erosion of the surface by sputtering, as well as redeposition of sputter ejecta, can occur over geologic time. The surface can also be chemically modified. Sputter ejecta can make important contributions to the atmosphere; sputtering provides a lower limit to the atmospheric column density even for arbitrarily cold satellite surfaces. Sputter ejecta escaping from the parent body can form extensive neutral clouds within the magnetosphere. Ionization and dissociation within these neutral clouds can be dominant sources of low-energy plasma. The importance of these processes is discussed for the satellites and magnetospheres of Jupiter, Saturn and Uranus

  14. Morphology, proliferation, and osteogenic differentiation of mesenchymal stem cells cultured on titanium, tantalum, and chromium surfaces

    DEFF Research Database (Denmark)

    Stiehler, Maik; Lind, M.; Mygind, Tina

    2007-01-01

    the interactions between human mesenchymal stem cells (MSCs) and smooth surfaces of titanium (Ti), tantalum (Ta), and chromium (Cr). Mean cellular area was quantified using fluorescence microscopy (4 h). Cellular proliferation was assessed by (3)H-thymidine incorporation and methylene blue cell counting assays (4...

  15. Current Understanding of Physicochemical Mechanisms for Cell Membrane Penetration of Arginine-rich Cell Penetrating Peptides: Role of Glycosaminoglycan Interactions.

    Science.gov (United States)

    Takechi-Haraya, Yuki; Saito, Hiroyuki

    2018-01-01

    Arginine-rich cell penetrating peptides (CPPs) are very promising drug carriers to deliver membrane-impermeable pharmaceuticals, such as siRNA, bioactive peptides and proteins. CPPs directly penetrate into cells across cell membranes via a spontaneous energy-independent process, in which CPPs appear to interact with acidic lipids in the outer leaflet of the cell membrane. However, acidic lipids represent only 10 to 20% of the total membrane lipid content and in mammalian cell membranes they are predominantly located in the inner leaflet. Alternatively, CPPs favorably bind in a charge density- dependent manner to negatively charged, sulfated glycosaminoglycans (GAGs), such as heparan sulfate and chondroitin sulfate, which are abundant on the cell surface and are involved in many biological functions. We have recently demonstrated that the interaction of CPPs with sulfated GAGs plays a critical role in their direct cell membrane penetration: the favorable enthalpy contribution drives the high-affinity binding of arginine-rich CPPs to sulfated GAGs, initiating an efficient cell membrane penetration. The favorable enthalpy gain is presumably mainly derived from a unique property of the guanidino group of arginine residues forming multidentate hydrogen bonding with sulfate and carboxylate groups in GAGs. Such interactions can be accompanied with charge neutralization of arginine-rich CPPs, promoting their partition into cell membranes. This review summarizes the current understanding of the physicochemical mechanism for lipid membrane penetration of CPPs, and discusses the role of the GAG interactions on the cell membrane penetration of CPPs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Cell behavior on microparticles with different surface morphology

    International Nuclear Information System (INIS)

    Huang Sha; Fu Xiaobing

    2010-01-01

    Microparticles can serve as substrates for cell amplification and deliver the cell aggregation to the site of the defect for tissue regeneration. To develop favorable microparticles for cell delivery application, we fabricated and evaluated three types of microparticles that differ in surface properties. The microparticles with varied surface morphology (smooth, pitted and multicavity) were created from chemically crosslinked gelatin particles that underwent various drying treatments. Three types of microparticles were characterized and assessed in terms of the cell behavior of human keratinocytes and fibroblasts seeded on them. The cells could attach, spread and proliferate on all types of microparticles but spread and populated more slowly on the microparticles with smooth surfaces than on those with pitted or multicavity surfaces. Microparticles with a multicavity surface demonstrated the highest cell attachment and growth rate. Furthermore, cells tested on microparticles with a multicavity surface exhibited better morphology and induced the earlier formation of extracellular-based cell-microparticle aggregation than those on microparticles with other surface morphology (smooth and pitted). Thus, microparticles with a multicavity surface show promise for attachment and proliferation of cells in tissue engineering.

  17. The Role of Cell Surface Architecture of Lactobacilli in Host-Microbe Interactions in the Gastrointestinal Tract

    Directory of Open Access Journals (Sweden)

    Ranjita Sengupta

    2013-01-01

    Full Text Available Lactobacillus species can exert health promoting effects in the gastrointestinal tract (GIT through many mechanisms, which include pathogen inhibition, maintenance of microbial balance, immunomodulation, and enhancement of the epithelial barrier function. Different species of the genus Lactobacillus can evoke different responses in the host, and not all strains of the same species can be considered beneficial. Strain variations may be related to diversity of the cell surface architecture of lactobacilli and the bacteria's ability to express certain surface components or secrete specific compounds in response to the host environment. Lactobacilli are known to modify their surface structures in response to stress factors such as bile and low pH, and these adaptations may help their survival in the face of harsh environmental conditions encountered in the GIT. In recent years, multiple cell surface-associated molecules have been implicated in the adherence of lactobacilli to the GIT lining, immunomodulation, and protective effects on intestinal epithelial barrier function. Identification of the relevant bacterial ligands and their host receptors is imperative for a better understanding of the mechanisms through which lactobacilli exert their beneficial effects on human health.

  18. Gold cleaning methods for preparation of cell culture surfaces for self-assembled monolayers of zwitterionic oligopeptides.

    Science.gov (United States)

    Enomoto, Junko; Kageyama, Tatsuto; Myasnikova, Dina; Onishi, Kisaki; Kobayashi, Yuka; Taruno, Yoko; Kanai, Takahiro; Fukuda, Junji

    2018-05-01

    Self-assembled monolayers (SAMs) have been used to elucidate interactions between cells and material surface chemistry. Gold surfaces modified with oligopeptide SAMs exhibit several unique characteristics, such as cell-repulsive surfaces, micropatterns of cell adhesion and non-adhesion regions for control over cell microenvironments, and dynamic release of cells upon external stimuli under culture conditions. However, basic procedures for the preparation of oligopeptide SAMs, including appropriate cleaning methods of the gold surface before modification, have not been fully established. Because gold surfaces are readily contaminated with organic compounds in the air, cleaning methods may be critical for SAM formation. In this study, we examined the effects of four gold cleaning methods: dilute aqua regia, an ozone water, atmospheric plasma, and UV irradiation. Among the methods, UV irradiation most significantly improved the formation of oligopeptide SAMs in terms of repulsion of cells on the surfaces. We fabricated an apparatus with a UV light source, a rotation table, and HEPA filter, to treat a number of gold substrates simultaneously. Furthermore, UV-cleaned gold substrates were capable of detaching cell sheets without serious cell injury. This may potentially provide a stable and robust approach to oligopeptide SAM-based experiments for biomedical studies. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  19. Surface Aggregation of Candida albicans on Glass in the Absence and Presence of Adhering Streptococcus gordonii in a Parallel-Plate Flow Chamber: A Surface Thermodynamical Analysis Based on Acid-Base Interactions.

    Science.gov (United States)

    Millsap; Bos; Busscher; van der Mei HC

    1999-04-15

    Adhesive interactions between yeasts and bacteria are important in the maintenance of infectious mixed biofilms on natural and biomaterial surfaces in the human body. In this study, the extended DLVO (Derjaguin-Landau-Verwey-Overbeek) approach has been applied to explain adhesive interactions between C. albicans ATCC 10261 and S. gordonii NCTC 7869 adhering on glass. Contact angles with different liquids and the zeta potentials of both the yeasts and bacteria were determined and their adhesive interactions were measured in a parallel-plate flow chamber.Streptococci were first allowed to adhere to the bottom glass plate of the flow chamber to different seeding densities, and subsequently deposition of yeasts was monitored with an image analysis system, yielding the degree of initial surface aggregation of the adhering yeasts and their spatial arrangement in a stationary end point. Irrespective of growth temperature, the yeast cells appeared uncharged in TNMC buffer, but yeasts grown at 37 degrees C were intrinsically more hydrophilic and had an increased electron-donating character than cells grown at 30 degrees C. All yeasts showed surface aggregation due to attractive Lifshitz-van der Waals forces. In addition, acid-base interactions between yeasts, yeasts and the glass substratum, and yeasts and the streptococci were attractive for yeasts grown at 30 degrees C, but yeasts grown at 37 degrees C only had favorable acid-base interactions with the bacteria, explaining the positive relationship between the surface coverage of the glass by streptococci and the surface aggregation of the yeasts. Copyright 1999 Academic Press.

  20. Flavonoid-membrane Interactions: A Protective Role of Flavonoids at the Membrane Surface?

    Directory of Open Access Journals (Sweden)

    Patricia I. Oteiza

    2005-01-01

    Full Text Available Flavonoids can exert beneficial health effects through multiple mechanisms. In this paper, we address the important, although not fully understood, capacity of flavonoids to interact with cell membranes. The interactions of polyphenols with bilayers include: (a the partition of the more non-polar compounds in the hydrophobic interior of the membrane, and (b the formation of hydrogen bonds between the polar head groups of lipids and the more hydrophilic flavonoids at the membrane interface. The consequences of these interactions are discussed. The induction of changes in membrane physical properties can affect the rates of membrane lipid and protein oxidation. The partition of certain flavonoids in the hydrophobic core can result in a chain breaking antioxidant activity. We suggest that interactions of polyphenols at the surface of bilayers through hydrogen bonding, can act to reduce the access of deleterious molecules (i.e. oxidants, thus protecting the structure and function of membranes.

  1. Structural Basis of the Interaction of a Trypanosoma cruzi Surface Molecule Implicated in Oral Infection with Host Cells and Gastric Mucin

    Science.gov (United States)

    Cortez, Cristian; Yoshida, Nobuko; Bahia, Diana; Sobreira, Tiago J.P.

    2012-01-01

    Host cell invasion and dissemination within the host are hallmarks of virulence for many pathogenic microorganisms. As concerns Trypanosoma cruzi, which causes Chagas disease, the insect vector-derived metacyclic trypomastigotes (MT) initiate infection by invading host cells, and later blood trypomastigotes disseminate to diverse organs and tissues. Studies with MT generated in vitro and tissue culture-derived trypomastigotes (TCT), as counterparts of insect-borne and bloodstream parasites, have implicated members of the gp85/trans-sialidase superfamily, MT gp82 and TCT Tc85-11, in cell invasion and interaction with host factors. Here we analyzed the gp82 structure/function characteristics and compared them with those previously reported for Tc85-11. One of the gp82 sequences identified as a cell binding site consisted of an α-helix, which connects the N-terminal β-propeller domain to the C-terminal β-sandwich domain where the second binding site is nested. In the gp82 structure model, both sites were exposed at the surface. Unlike gp82, the Tc85-11 cell adhesion sites are located in the N-terminal β-propeller region. The gp82 sequence corresponding to the epitope for a monoclonal antibody that inhibits MT entry into target cells was exposed on the surface, upstream and contiguous to the α-helix. Located downstream and close to the α-helix was the gp82 gastric mucin binding site, which plays a central role in oral T. cruzi infection. The sequences equivalent to Tc85-11 laminin-binding sites, which have been associated with the parasite ability to overcome extracellular matrices and basal laminae, was poorly conserved in gp82, compatible with its reduced capacity to bind laminin. Our study indicates that gp82 is structurally suited for MT to initiate infection by the oral route, whereas Tc85-11, with its affinity for laminin, would facilitate the parasite dissemination through diverse organs and tissues. PMID:22860068

  2. Targeting and molecular imaging of HepG2 cells using surface-functionalized gold nanoparticles

    International Nuclear Information System (INIS)

    Rathinaraj, Pierson; Lee, Kyubae; Choi, Yuri; Park, Soo-Young; Kwon, Oh Hyeong; Kang, Inn-Kyu

    2015-01-01

    Mercaptosuccinic acid (M)-conjugated gold nanoparticles (GM) were prepared and characterized by transmission electron microscope and dynamic light scattering. M was used to improve the monodispersity and non-specific intracellular uptake of nanoparticles. Lactobionic acid (L) was subsequently conjugated to the GM to target preferentially HepG2 cells (liver cancer cells) that express asialoglycoprotein receptors (ASGPR) on their membrane surfaces and facilitate the transit of nanoparticles across the cell membrane. The mean size of lactobionic acid-conjugated gold nanoparticle (GL) was approximately 10 ± 0.2 nm. Finally, the Atto 680 dye (A6) was coupled to the nanoparticles to visualize their internalization into HepG2 cells. The interaction of surface-modified gold nanoparticles with HepG2 cells was studied after culturing cells in media containing the GM or L-conjugated GM (GL)

  3. Targeting and molecular imaging of HepG2 cells using surface-functionalized gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rathinaraj, Pierson [Auckland University of Technology, Institute of Biomedical Technologies (New Zealand); Lee, Kyubae; Choi, Yuri; Park, Soo-Young [Kyungpook National University, School of Applied Chemical Engineering, Graduate School (Korea, Republic of); Kwon, Oh Hyeong [Kumoh National Institute of Technology, Department of Polymer Science and Engineering (Korea, Republic of); Kang, Inn-Kyu, E-mail: ikkang@knu.ac.kr [Kyungpook National University, School of Applied Chemical Engineering, Graduate School (Korea, Republic of)

    2015-07-15

    Mercaptosuccinic acid (M)-conjugated gold nanoparticles (GM) were prepared and characterized by transmission electron microscope and dynamic light scattering. M was used to improve the monodispersity and non-specific intracellular uptake of nanoparticles. Lactobionic acid (L) was subsequently conjugated to the GM to target preferentially HepG2 cells (liver cancer cells) that express asialoglycoprotein receptors (ASGPR) on their membrane surfaces and facilitate the transit of nanoparticles across the cell membrane. The mean size of lactobionic acid-conjugated gold nanoparticle (GL) was approximately 10 ± 0.2 nm. Finally, the Atto 680 dye (A6) was coupled to the nanoparticles to visualize their internalization into HepG2 cells. The interaction of surface-modified gold nanoparticles with HepG2 cells was studied after culturing cells in media containing the GM or L-conjugated GM (GL)

  4. On the role of Nb-related sites of an oxidized β-TiNb alloy surface in its interaction with osteoblast-like MG-63 cells

    Energy Technology Data Exchange (ETDEWEB)

    Jirka, Ivan, E-mail: Ivan.Jirka@jh-inst.cas.cz [J. Heyrovský Institute of Physical Chemistry, Acad. Sci. CR, v.v.i. Dolejškova 3, 182 23 Prague 8 (Czech Republic); Vandrovcová, Marta [Institute of Physiology, Acad. Sci. CR, v.v.i., Vídeňská 1083, Prague 4 (Czech Republic); Frank, Otakar [J. Heyrovský Institute of Physical Chemistry, Acad. Sci. CR, v.v.i. Dolejškova 3, 182 23 Prague 8 (Czech Republic); Tolde, Zdeněk [Faculty of Mechanical Engineering, Czech Technical University in Prague, Institute of Materials Engineering, Karlovo nám. 13, Prague 2 (Czech Republic); Plšek, Jan [J. Heyrovský Institute of Physical Chemistry, Acad. Sci. CR, v.v.i. Dolejškova 3, 182 23 Prague 8 (Czech Republic); Luxbacher, Thomas [Anton Paar GmbH, Anton Paar Str. 20, 8054 Graz (Austria); Bačáková, Lucie [Institute of Physiology, Acad. Sci. CR, v.v.i., Vídeňská 1083, Prague 4 (Czech Republic); Starý, Vladimír [Faculty of Mechanical Engineering, Czech Technical University in Prague, Institute of Materials Engineering, Karlovo nám. 13, Prague 2 (Czech Republic)

    2013-04-01

    β-Stabilized titanium (Ti) alloys containing non-toxic elements, particularly niobium (Nb), are promising materials for the construction of bone implants. Their biocompatibility can be further increased by oxidation of their surface. Therefore, in this study, the adhesion, growth and viability of human osteoblast-like MG 63 cells in cultures on oxidized surfaces of a β-TiNb alloy were investigated and compared with the cell behavior on thermally oxidized Ti, i.e. a metal commonly used for constructing bone implants. Four experimental groups of samples were prepared: Ti or TiNb samples annealed to 600 °C for 60 min in a stream of dry air, and Ti and TiNb samples treated in Piranha solution prior to annealing. We found that on all TiNb-based samples, the cell population densities on days 1, 3 and 7 after seeding were higher than on the corresponding Ti-based samples. As revealed by XPS and Raman spectroscopy, and also by isoelectric point measurements, these results can be attributed to the presence of T-Nb{sub 2}O{sub 5} oxide phase in the surface of the alloy sample, which decreased its negative zeta (ζ)-potential in comparison with zeta (ζ)-potential of the Ti sample at physiological pH. This effect was tentatively explained by the presence of positively charged defects acting as Lewis sites of the surface Nb{sub 2}O{sub 5} phase. Piranha treatment slightly decreases the biocompatibility of the samples, which for the alloy samples may be explained by a decrease in the number of defective sites with this treatment. Thus, the presence of Nb and thermal oxidation of β-stabilized Ti alloys play a significant role in the increased biocompatibility of TiNb alloys. - Highlights: ► T-Nb{sub 2}O{sub 5} and rutile are the main components of the oxidized β-TiNb alloy surface. ► Negative value of ζ potential is reduced by presence of Nb in the alloy surface. ► Less negative ζ potential is beneficial for interaction of the alloy with cells. ► The β-TiNb alloy

  5. Surfaceome and Proteosurfaceome in Parietal Monoderm Bacteria: Focus on Protein Cell-Surface Display

    Directory of Open Access Journals (Sweden)

    Mickaël Desvaux

    2018-02-01

    Full Text Available The cell envelope of parietal monoderm bacteria (archetypal Gram-positive bacteria is formed of a cytoplasmic membrane (CM and a cell wall (CW. While the CM is composed of phospholipids, the CW is composed at least of peptidoglycan (PG covalently linked to other biopolymers, such as teichoic acids, polysaccharides, and/or polyglutamate. Considering the CW is a porous structure with low selective permeability contrary to the CM, the bacterial cell surface hugs the molecular figure of the CW components as a well of the external side of the CM. While the surfaceome corresponds to the totality of the molecules found at the bacterial cell surface, the proteinaceous complement of the surfaceome is the proteosurfaceome. Once translocated across the CM, secreted proteins can either be released in the extracellular milieu or exposed at the cell surface by associating to the CM or the CW. Following the gene ontology (GO for cellular components, cell-surface proteins at the CM can either be integral (GO: 0031226, i.e., the integral membrane proteins, or anchored to the membrane (GO: 0046658, i.e., the lipoproteins. At the CW (GO: 0009275, cell-surface proteins can be covalently bound, i.e., the LPXTG-proteins, or bound through weak interactions to the PG or wall polysaccharides, i.e., the cell wall binding proteins. Besides monopolypeptides, some proteins can associate to each other to form supramolecular protein structures of high molecular weight, namely the S-layer, pili, flagella, and cellulosomes. After reviewing the cell envelope components and the different molecular mechanisms involved in protein attachment to the cell envelope, perspectives in investigating the proteosurfaceome in parietal monoderm bacteria are further discussed.

  6. Biocompatibility of the titanium-based implant surfaces: Effect of the calcium dihydrogen phosphate on osteoblast cells

    Directory of Open Access Journals (Sweden)

    Kaluđerović Milena R.

    2016-01-01

    Full Text Available The influence of the presence of calcium dihydrogen phosphate in acid media on titanium-based implant surfaces, Ticer, employed in clinics, and its white form (Ticer white, on osteoblast cells was investigated. Novel surfaces M1 and M2 were obtained by immersing Ticer and Ticer white surfaces in calcium dihydrogen phosphate solution at pH 3.5. The surfaces were characterized by SEM, EDS and X-ray diffraction. The results related to interaction of investigated surfaces and human osteoblast cells from indirect biocompatibility (MTT and SRB assays, proliferation (DAPI assay and mode of cell death (acridine orange/ethidium bromide (AO/EB double staining were found to be in good agreement, as well as findings from osteocalcin (OC and bone sialoprotein (BSP expression. Surfaces were obtained by employing anodic plasma-electrochemical oxidation with spark discharges without subsequent surface modifications were found to be more compatible. Soaking of Ticer and Ticer white in phosphate solution gave toxic materials (M1 and M2 which induced apoptosis and secondary necrosis in osteoblast cells.

  7. Cellular Homeostasis and Antioxidant Response in Epithelial HT29 Cells on Titania Nanotube Arrays Surface

    Directory of Open Access Journals (Sweden)

    Rabiatul Basria SMN Mydin

    2017-01-01

    Full Text Available Cell growth and proliferative activities on titania nanotube arrays (TNA have raised alerts on genotoxicity risk. Present toxicogenomic approach focused on epithelial HT29 cells with TNA surface. Fledgling cell-TNA interaction has triggered G0/G1 cell cycle arrests and initiates DNA damage surveillance checkpoint, which possibly indicated the cellular stress stimuli. A profound gene regulation was observed to be involved in cellular growth and survival signals such as p53 and AKT expressions. Interestingly, the activation of redox regulator pathways (antioxidant defense was observed through the cascade interactions of GADD45, MYC, CHECK1, and ATR genes. These mechanisms furnish to protect DNA during cellular division from an oxidative challenge, set in motion with XRRC5 and RAD50 genes for DNA damage and repair activities. The cell fate decision on TNA-nanoenvironment has been reported to possibly regulate proliferative activities via expression of p27 and BCL2 tumor suppressor proteins, cogent with SKP2 and BCL2 oncogenic proteins suppression. Findings suggested that epithelial HT29 cells on the surface of TNA may have a positive regulation via cell-homeostasis mechanisms: a careful circadian orchestration between cell proliferation, survival, and death. This nanomolecular knowledge could be beneficial for advanced medical applications such as in nanomedicine and nanotherapeutics.

  8. Surface glycosaminoglycans mediate adherence between HeLa cells and Lactobacillus salivarius Lv72.

    Science.gov (United States)

    Martín, Rebeca; Martín, Carla; Escobedo, Susana; Suárez, Juan E; Quirós, Luis M

    2013-09-17

    The adhesion of lactobacilli to the vaginal surface is of paramount importance to develop their probiotic functions. For this reason, the role of HeLa cell surface proteoglycans in the attachment of Lactobacillus salivarius Lv72, a mutualistic strain of vaginal origin, was investigated. Incubation of cultures with a variety of glycosaminoglycans (chondroitin sulfate A and C, heparin and heparan sulfate) resulted in marked binding interference. However, no single glycosaminoglycan was able to completely abolish cell binding, the sum of all having an additive effect that suggests cooperation between them and recognition of specific adhesins on the bacterial surface. In contrast, chondroitin sulfate B enhanced cell to cell attachment, showing the relevance of the stereochemistry of the uronic acid and the sulfation pattern on binding. Elimination of the HeLa surface glycosaminoglycans with lyases also resulted in severe adherence impairment. Advantage was taken of the Lactobacillus-glycosaminoglycans interaction to identify an adhesin from the bacterial surface. This protein, identify as a soluble binding protein of an ABC transporter system (OppA) by MALDI-TOF/(MS), was overproduced in Escherichia coli, purified and shown to interfere with L. salivarius Lv72 adhesion to HeLa cells. These data suggest that glycosaminoglycans play a fundamental role in attachment of mutualistic bacteria to the epithelium that lines the cavities where the normal microbiota thrives, OppA being a bacterial adhesin involved in the process.

  9. A molecular smart surface for spatio-temporal studies of cell mobility.

    Science.gov (United States)

    Lee, Eun-ju; Luo, Wei; Chan, Eugene W L; Yousaf, Muhammad N

    2015-01-01

    Active migration in both healthy and malignant cells requires the integration of information derived from soluble signaling molecules with positional information gained from interactions with the extracellular matrix and with other cells. How a cell responds and moves involves complex signaling cascades that guide the directional functions of the cytoskeleton as well as the synthesis and release of proteases that facilitate movement through tissues. The biochemical events of the signaling cascades occur in a spatially and temporally coordinated manner then dynamically shape the cytoskeleton in specific subcellular regions. Therefore, cell migration and invasion involve a precise but constantly changing subcellular nano-architecture. A multidisciplinary effort that combines new surface chemistry and cell biological tools is required to understand the reorganization of cytoskeleton triggered by complex signaling during migration. Here we generate a class of model substrates that modulate the dynamic environment for a variety of cell adhesion and migration experiments. In particular, we use these dynamic substrates to probe in real-time how the interplay between the population of cells, the initial pattern geometry, ligand density, ligand affinity and integrin composition affects cell migration and growth. Whole genome microarray analysis indicates that several classes of genes ranging from signal transduction to cytoskeletal reorganization are differentially regulated depending on the nature of the surface conditions.

  10. Interactions between whey proteins and kaolinite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Barral, S. [Department of Chemical Engineering and Environmental Technology, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain); Villa-Garcia, M.A. [Department of Organic and Inorganic Chemistry, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain)], E-mail: mavg@uniovi.es; Rendueles, M. [Project Management Area, University of Oviedo, Independencia 13, 33004 Oviedo (Spain); Diaz, M. [Department of Chemical Engineering and Environmental Technology, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain)

    2008-07-15

    The nature of the interactions between whey proteins and kaolinite surfaces was investigated by adsorption-desorption experiments at room temperature, performed at the isoelectric point (IEP) of the proteins and at pH 7. It was found that kaolinite is a strong adsorbent for proteins, reaching the maximum adsorption capacity at the IEP of each protein. At pH 7.0, the retention capacity decreased considerably. The adsorption isotherms showed typical Langmuir characteristics. X-ray diffraction data for the protein-kaolinite complexes showed that protein molecules were not intercalated in the mineral structure, but immobilized at the external surfaces and the edges of the kaolinite. Fourier transform IR results indicate the absence of hydrogen bonding between kaolinite surfaces and the polypeptide chain. The adsorption patterns appear to be related to electrostatic interactions, although steric effects should be also considered.

  11. Interactions between whey proteins and kaolinite surfaces

    International Nuclear Information System (INIS)

    Barral, S.; Villa-Garcia, M.A.; Rendueles, M.; Diaz, M.

    2008-01-01

    The nature of the interactions between whey proteins and kaolinite surfaces was investigated by adsorption-desorption experiments at room temperature, performed at the isoelectric point (IEP) of the proteins and at pH 7. It was found that kaolinite is a strong adsorbent for proteins, reaching the maximum adsorption capacity at the IEP of each protein. At pH 7.0, the retention capacity decreased considerably. The adsorption isotherms showed typical Langmuir characteristics. X-ray diffraction data for the protein-kaolinite complexes showed that protein molecules were not intercalated in the mineral structure, but immobilized at the external surfaces and the edges of the kaolinite. Fourier transform IR results indicate the absence of hydrogen bonding between kaolinite surfaces and the polypeptide chain. The adsorption patterns appear to be related to electrostatic interactions, although steric effects should be also considered

  12. Combined Contamination and Space Environmental Effects on Solar Cells and Thermal Control Surfaces

    Science.gov (United States)

    Dever, Joyce A.; Bruckner, Eric J.; Scheiman, David A.; Stidham, Curtis R.

    1994-01-01

    For spacecraft in low Earth orbit (LEO), contamination can occur from thruster fuel, sputter contamination products and from products of silicone degradation. This paper describes laboratory testing in which solar cell materials and thermal control surfaces were exposed to simulated spacecraft environmental effects including contamination, atomic oxygen, ultraviolet radiation and thermal cycling. The objective of these experiments was to determine how the interaction of the natural LEO environmental effects with contaminated spacecraft surfaces impacts the performance of these materials. Optical properties of samples were measured and solar cell performance data was obtained. In general, exposure to contamination by thruster fuel resulted in degradation of solar absorptance for fused silica and various thermal control surfaces and degradation of solar cell performance. Fused silica samples which were subsequently exposed to an atomic oxygen/vacuum ultraviolet radiation environment showed reversal of this degradation. These results imply that solar cells and thermal control surfaces which are susceptible to thruster fuel contamination and which also receive atomic oxygen exposure may not undergo significant performance degradation. Materials which were exposed to only vacuum ultraviolet radiation subsequent to contamination showed slight additional degradation in solar absorptance.

  13. Surface plasmon effects in the absorption enhancements of amorphous silicon solar cells with periodical metal nanowall and nanopillar structures.

    Science.gov (United States)

    Lin, Hung-Yu; Kuo, Yang; Liao, Cheng-Yuan; Yang, C C; Kiang, Yean-Woei

    2012-01-02

    The authors numerically investigate the absorption enhancement of an amorphous Si solar cell, in which a periodical one-dimensional nanowall or two-dimensional nanopillar structure of the Ag back-reflector is fabricated such that a dome-shaped grating geometry is formed after Si deposition and indium-tin-oxide coating. In this investigation, the effects of surface plasmon (SP) interaction in such a metal nanostructure are of major concern. Absorption enhancement in most of the solar spectral range of significant amorphous Si absorption (320-800 nm) is observed in a grating solar cell. In the short-wavelength range of high amorphous Si absorption, the weakly wavelength-dependent absorption enhancement is mainly caused by the broadband anti-reflection effect, which is produced through the surface nano-grating structures. In the long-wavelength range of diminishing amorphous Si absorption, the highly wavelength-sensitive absorption enhancement is mainly caused by Fabry-Perot resonance and SP interaction. The SP interaction includes the contributions of surface plasmon polariton and localized surface plasmon.

  14. Cross-Surface: Workshop on Interacting with Multi-Device Ecologies in the Wild

    DEFF Research Database (Denmark)

    Houben, Steven; Vermeulen, Jo; Klokmose, Clemens Nylandsted

    2015-01-01

    In this workshop, we will review and discuss opportunities, technical challenges and problems with cross-device interactions in interactive multi-surface and multi-device ecologies. We aim to bring together researchers and practitioners currently working on novel techniques for cross......-surface interactions, identify application domains and enabling technologies for cross-surface interactions in the wild, and establish a research community to develop effective strategies for successful design of cross-device interactions....

  15. Biomolecular strategies for cell surface engineering

    Science.gov (United States)

    Wilson, John Tanner

    Islet transplantation has emerged as a promising cell-based therapy for the treatment of diabetes, but its clinical efficacy remains limited by deleterious host responses that underlie islet destruction. In this dissertation, we describe the assembly of ultrathin conformal coatings that confer molecular-level control over the composition and biophysicochemical properties of the islet surface with implications for improving islet engraftment. Significantly, this work provides novel biomolecular strategies for cell surface engineering with broad biomedical and biotechnological applications in cell-based therapeutics and beyond. Encapsulation of cells and tissue offers a rational approach for attenuating deleterious host responses towards transplanted cells, but a need exists to develop cell encapsulation strategies that minimize transplant volume. Towards this end, we endeavored to generate nanothin films of diverse architecture with tunable properties on the extracellular surface of individual pancreatic islets through a process of layer-by-layer (LbL) self assembly. We first describe the formation of poly(ethylene glycol) (PEG)-rich conformal coatings on islets via LbL self assembly of poly(L-lysine)-g-PEG(biotin) and streptavidin. Multilayer thin films conformed to the geometrically and chemically heterogeneous islet surface, and could be assembled without loss of islet viability or function. Significantly, coated islets performed comparably to untreated controls in a murine model of allogenic intraportal islet transplantation, and, to our knowledge, this is the first study to report in vivo survival and function of nanoencapsulated cells or cell aggregates. Based on these findings, we next postulated that structurally similar PLL-g-PEG copolymers comprised of shorter PEG grafts might be used to initiate and propagate the assembly of polyelectrolyte multilayer (PEM) films on pancreatic islets, while simultaneously preserving islet viability. Through control of PLL

  16. Cell Adhesion on Surface-Functionalized Magnesium.

    Science.gov (United States)

    Wagener, Victoria; Schilling, Achim; Mainka, Astrid; Hennig, Diana; Gerum, Richard; Kelch, Marie-Luise; Keim, Simon; Fabry, Ben; Virtanen, Sannakaisa

    2016-05-18

    The biocompatibility of commercially pure magnesium-based (cp Mg) biodegradable implants is compromised of strong hydrogen evolution and surface alkalization due to high initial corrosion rates of cp Mg in the physiological environment. To mitigate this problem, the addition of corrosion-retarding alloying elements or coating of implant surfaces has been suggested. In the following work, we explored the effect of organic coatings on long-term cell growth. cp Mg was coated with aminopropyltriehtoxysilane + vitamin C (AV), carbonyldiimidazole (CDI), or stearic acid (SA). All three coatings have been previously suggested to reduce initial corrosion and to enhance protein adsorption and hence cell adhesion on magnesium surfaces. Endothelial cells (DH1+/+) and osteosarcoma cells (MG63) were cultured on coated samples for up to 20 days. To quantify Mg corrosion, electrochemical impedance spectroscopy (EIS) was measured after 1, 3, and 5 days of cell culture. We also investigated the speed of initial cell spreading after seeding using fluorescently labeled fibroblasts (NIH/3T3). Hydrogen evolution after contact with cell culture medium was markedly decreased on AV- and SA-coated Mg compared to uncoated Mg. These coatings also showed improved cell adhesion and spreading after 24 h of culture comparable to tissue-treated plastic surfaces. On AV-coated cp Mg, a confluent layer of endothelial cells formed after 5 days and remained intact for up to 20 days. Together, these data demonstrate that surface coating with AV is a viable strategy for improving long-term biocompatibility of cp Mg-based implants. EIS measurements confirmed that the presence of a confluent cell layer increased the corrosion resistance.

  17. Nanoparticle-Cell Interaction: A Cell Mechanics Perspective.

    Science.gov (United States)

    Septiadi, Dedy; Crippa, Federica; Moore, Thomas Lee; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

    2018-05-01

    Progress in the field of nanoparticles has enabled the rapid development of multiple products and technologies; however, some nanoparticles can pose both a threat to the environment and human health. To enable their safe implementation, a comprehensive knowledge of nanoparticles and their biological interactions is needed. In vitro and in vivo toxicity tests have been considered the gold standard to evaluate nanoparticle safety, but it is becoming necessary to understand the impact of nanosystems on cell mechanics. Here, the interaction between particles and cells, from the point of view of cell mechanics (i.e., bionanomechanics), is highlighted and put in perspective. Specifically, the ability of intracellular and extracellular nanoparticles to impair cell adhesion, cytoskeletal organization, stiffness, and migration are discussed. Furthermore, the development of cutting-edge, nanotechnology-driven tools based on the use of particles allowing the determination of cell mechanics is emphasized. These include traction force microscopy, colloidal probe atomic force microscopy, optical tweezers, magnetic manipulation, and particle tracking microrheology. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Cell surface binding and uptake of arginine- and lysine-rich penetratin peptides in absence and presence of proteoglycans

    KAUST Repository

    Å mand, Helene L.; Rydberg, Hanna A.; Fornander, Louise H.; Lincoln, Per; Nordé n, Bengt; Esbjö rner, Elin K.

    2012-01-01

    Cell surface proteoglycans (PGs) appear to promote uptake of arginine-rich cell-penetrating peptides (CPPs), but their exact functions are unclear. To address if there is specificity in the interactions of arginines and PGs leading to improved

  19. Biocompatibility of Ir/Ti-oxide coatings: Interaction with platelets, endothelial and smooth muscle cells

    Science.gov (United States)

    Habibzadeh, Sajjad; Li, Ling; Omanovic, Sasha; Shum-Tim, Dominique; Davis, Elaine C.

    2014-05-01

    Applying surface coatings on a biomedical implant is a promising modification technique which can enhance the implant's biocompatibility via controlling blood constituents- or/and cell-surface interaction. In this study, the influence of composition of IrxTi1-x-oxide coatings (x = 0, 0.2, 0.4, 0.6, 0.8, 1) formed on a titanium (Ti) substrate on the responses of platelets, endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. The results showed that a significant decrease in platelet adhesion and activation was obtained on Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, rendering the surfaces more blood compatible, in comparison to the control (316L stainless steel, 316L-SS) and other coating compositions. Further, a substantial increase in the EC/SMC surface count ratio after 4 h of cell attachment to the Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, relative to the 316L-SS control and the other coating compositions, indicated high potential of these coatings for the enhancement of surface endothelialization. This indicates the capability of the corresponding coating compositions to promote EC proliferation on the surface, while inhibiting that of SMCs, which is important in cardiovascular stents applications.

  20. Cell surface GRP78 facilitates hepatoma cells proliferation and migration by activating IGF-IR.

    Science.gov (United States)

    Yin, Yancun; Chen, Chen; Chen, Jinliang; Zhan, Renhui; Zhang, Qiang; Xu, Xiaoyan; Li, Defang; Li, Minjing

    2017-07-01

    The 78kDa glucose regulated protein (GRP78) is a multifunctional chaperone that is involved in a variety of cellular processes. Insulin like growth factor I receptor (IGF-IR) often aberrant expresses in many types of tumor cells. The IGF-IR signaling plays key roles in carcinogenesis and maintenance of the malignant phenotype. The crosstalk between GRP78 and IGF-IR molecules has not well been illuminated. Here, we demonstrated a reciprocal regulation of GRP78 expression and IGF-IR pathway activation. IGF-I induced GRP78 expression in hepatoma cells. IGF-IR knockdown or IGF-IR inhibitor repressed GRP78 expression. Both phosphatidylinositol 3-kianase (PI3K) and mitogen-activated protein kinase (MAPK) pathways involved in IGF-I induction of GRP78 expression. Interestingly, treatment of hepatoma cells with IGF-I re-distributes GRP78 from endoplasmic reticulum (ER) to cell surface and promotes its physical interaction with IGF-IR. Also, GRP78 promotes IGF-IR phosphorylation and activation. Blocked of GRP78 by small interfering RNA or inhibition of GRP78 function by (-)-epigallocatechin gallate (EGCG) blocks IGF-I induced IGF-IR phosphorylation and its downstream signaling. Further, blocked cell surface GRP78 with antibody inhibits IGF-I stimulated cellular proliferation and migration. These data reveal an essential role for the molecular chaperone GRP78 in IGF-IR signaling and implicate the use of GRP78 inhibitors in blocking IGF-IR signaling in hepatoma cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Diverse Profiles of Ricin-Cell Interactions in the Lung Following Intranasal Exposure to Ricin

    Directory of Open Access Journals (Sweden)

    Anita Sapoznikov

    2015-11-01

    Full Text Available Ricin, a plant-derived exotoxin, inhibits protein synthesis by ribosomal inactivation. Due to its wide availability and ease of preparation, ricin is considered a biothreat, foremost by respiratory exposure. We examined the in vivo interactions between ricin and cells of the lungs in mice intranasally exposed to the toxin and revealed multi-phasic cell-type-dependent binding profiles. While macrophages (MΦs and dendritic cells (DCs displayed biphasic binding to ricin, monophasic binding patterns were observed for other cell types; epithelial cells displayed early binding, while B cells and endothelial cells bound toxin late after intoxication. Neutrophils, which were massively recruited to the intoxicated lung, were refractive to toxin binding. Although epithelial cells bound ricin as early as MΦs and DCs, their rates of elimination differed considerably; a reduction in epithelial cell counts occurred late after intoxication and was restricted to alveolar type II cells only. The differential binding and cell-elimination patterns observed may stem from dissimilar accessibility of the toxin to different cells in the lung and may also reflect unequal interactions of the toxin with different cell-surface receptors. The multifaceted interactions observed in this study between ricin and the various cells of the target organ should be considered in the future development of efficient post-exposure countermeasures against ricin intoxication.

  2. Understanding and exploiting nanoscale surface heterogeneity for particle and cell manipulation

    Science.gov (United States)

    Kalasin, Surachate

    signatures. Following the approach taken by biophysicists for describing the interactions of leukocytes with the endothelial vasculature near an injury, the state spaces in this thesis map regimes of free particle motion, immediate firm arrest, and persistent rolling against macroscopic average patch density, Debye length, particle size, and shear rate. Surprisingly, the electrostatic heterogeneity state space resembles that for selectin-mediated leukocyte motion, and reasons are put forth. This finding is important because it demonstrates how synthetic nanoscale constructs can be exploited to achieve the selective cell capture mechanism previously attributed only to specialized cell adhesion molecules. This thesis initiates studies that extend these fundamental principles, developed for a tunable and well-characterized synthetic model to biological systems. For instance, it is demonstrated that general behaviors seen with the electrostatic model are observed when fibrinogen proteins are substituted for the electrostatic patches. This shows that the nature of the attractions is immaterial to adhesion, and that the effect of added salt primarily alters the range of the electrostatic repulsion and, correspondingly, the contact area. Also, studies with Staphylococcus aureus run parallel to those employing 1 mum silica spheres, further translating the concepts. Inaugural studies with mammalian cells, in the future work section, indicate that application of the surface heterogeneity approach to cell manipulation holds much future promise.

  3. Interaction between liquid droplets and heated surface

    Energy Technology Data Exchange (ETDEWEB)

    Nigmatulin, B I [Research and Engineering Centre, LWR Nuclear Plants Safety, Elektrogorsk (Russian Federation); Vasiliev, N I [Research and Engineering Centre, LWR Nuclear Plants Safety, Elektrogorsk (Russian Federation); Guguchkin, V V [Research and Engineering Centre, LWR Nuclear Plants Safety, Elektrogorsk (Russian Federation)

    1993-06-01

    In this paper, experimental methods and investigation results of interaction between droplets of different liquids and a heated surface are presented. Wetted area, contact time period and transition boundary from wetted to non-wetted interaction regimes are experimentally evaluated. A simple connection of the wetted area value and contact time period with the heat removal efficiency is shown. (orig.)

  4. Vp130, a chloroviral surface protein that interacts with the host Chlorella cell wall

    International Nuclear Information System (INIS)

    Onimatsu, Hideki; Sugimoto, Ichiro; Fujie, Makoto; Usami, Shoji; Yamada, Takashi

    2004-01-01

    A protein, Vp130, that interacts with the host cell wall was isolated from Chlorovirus CVK2. From its peptide sequence, the gene for Vp130 was identified on the PBCV-1 genomic sequence as an ORF combining A140R and A145R. In Vp130, the N-terminus was somehow modified and the C-terminus was occupied by 23-26 tandem repeats of a PAPK motif. In the internal region, Vp130 contained seven repeats of 70-73 amino acids, each copy of which was separated by PAPK sequences. This protein was well conserved among NC64A viruses. A recombinant rVp130N protein formed in Escherichia coli was shown not only to bind directly to the host cell wall in vitro but also to specifically bind to the host cells, as demonstrated by fluorescence microscopy. Because externally added rVp130N competed with CVK2 to bind to host cells, Vp130 is most likely to be a host-recognizing protein on the virion

  5. Effects of Titanium Surface Microtopography and Simvastatin on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells in Estrogen-Deprived Cell Culture.

    Science.gov (United States)

    Arpornmaeklong, Premjit; Pripatnanont, Prisana; Chookiatsiri, Chonticha; Tangtrakulwanich, Boonsin

    This study aimed to investigate the effects of titanium surface topography and simvastatin on growth and osteogenic differentiation of human bone marrow stromal cells (hBMSCs) in estrogen-deprived (ED) cell culture. Human BMSCs were seeded on cell culture plates, smooth-surface titanium (Ti) disks, and sandblasted with large grits and acid etched (SLA)-surface Ti disks; and subsequently cultured in regular (fetal bovine serum [FBS]), ED, and ED-with 100 nM simvastatin (ED-SIM) culture media for 14 to 21 days. Live/dead cell staining, scanning electron microscope examination, and cell viability assay were performed to determine cell attachment, morphology, and growth. Expression levels of osteoblast-associated genes, Runx2 and bone sialoprotein and levels of alkaline phosphatase (ALP) activity, calcium content, and osteocalcin in culture media were measured to determine osteoblastic differentiation. Expression levels of bone morphogenetic protein-2 (BMP-2) were investigated to examine stimulating effects of simvastatin (n = 4 to 5, mean ± SD). In vitro mineralization was verified by calcein staining. Human BMSCs exhibited different attachment and shapes on smooth and SLA titanium surfaces. Estrogen-deprived cell culture decreased cell attachment and growth, particularly on the SLA titanium surface, but cells were able to grow to reach confluence on day 21 in the ED-osteogenic (OS) culture medium. Promoting effects of the SLA titanium surface in ED-OS were significantly decreased. Simvastatin significantly increased osteogenic differentiation of human BMSCs on the SLA titanium surface in the ED-OS medium, and the promoting effects of simvastatin corresponded with the increasing of BMP-2 gene expression on the SLA titanium surface in ED-OS-SIM culture medium. The ED cell culture model provided a well-defined platform for investigating the effects of hormones and growth factors on cells and titanium surface interaction. Titanium, the SLA surface, and simvastatin

  6. Electron emission during multicharged ion-metal surface interactions

    International Nuclear Information System (INIS)

    Zeijlmans van Emmichoven, P.A.; Havener, C.C.; Hughes, I.G.; Overbury, S.H.; Robinson, M.T.; Zehner, D.M.; Meyer, F.W.

    1992-01-01

    The electron emission during multicharged ion-metal surface interactions will be discussed. The interactions lead to the emission of a significant number of electrons. Most of these electrons have energies below 30 eV. For incident ions with innershell vacancies the emission of Auger electrons that fill these vacancies has been found to occur mainly below the surface. We will present recently measured electron energy distributions which will be used to discuss the mechanisms that lead to the emission of Auger and of low-energy electrons

  7. Surface complexation of neptunium (V) onto whole cells and cell componets of Shewanella alga

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Donald Timothy [Los Alamos National Laboratory; Deo, Randhir P [ASU; Rittmann, Bruce E [ASU; Songkasiri, Warinthorn [UNAFFILIATED

    2008-01-01

    We systematically quantified surface complexation of neptunium(V) onto whole cells of Shewanella alga strain BrY and onto cell wall and extracellular polymeric substances (EPS) of S. alga. We first performed acid and base titrations and used the mathematical model FITEQL with constant-capacitance surface-complexation to determine the concentrations and deprotonation constants of specific surface functional groups. Deprotonation constants most likely corresponded to a carboxyl site associated with amino acids (pK{sub a} {approx} 2.4), a carboxyl group not associated with amino acids (pK{sub a} {approx} 5), a phosphoryl site (pK{sub a} {approx} 7.2), and an amine site (pK{sub a} > 10). We then carried out batch sorption experiments with Np(V) and each of the S. alga components at different pHs. Results show that solution pH influenced the speciation of Np(V) and each of the surface functional groups. We used the speciation sub-model of the biogeochemical model CCBATCH to compute the stability constants for Np(V) complexation to each surface functional group. The stability constants were similar for each functional group on S. alga bacterial whole cells, cell walls, and EPS, and they explain the complicated sorption patterns when they are combined with the aqueous-phase speciation of Np(V). For pH < 8, NpO{sub 2}{sup +} was the dominant form of Np(V), and its log K values for the low-pK{sub a} carboxyl, other carboxyl, and phosphoryl groups were 1.75, 1.75, and 2.5 to 3.1, respectively. For pH greater than 8, the key surface ligand was amine >XNH3+, which complexed with NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-}. The log K for NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-} complexed onto the amine groups was 3.1 to 3.6. All of the log K values are similar to those of Np(V) complexes with aqueous carboxyl and N-containing carboxyl ligands. These results point towards the important role of surface complexation in defining key actinide-microbiological interactions in the subsurface.

  8. The angiogenic behaviors of human umbilical vein endothelial cells (HUVEC) in co-culture with osteoblast-like cells (MG-63) on different titanium surfaces.

    Science.gov (United States)

    Shi, Bin; Andrukhov, Oleh; Berner, Simon; Schedle, Andreas; Rausch-Fan, Xiaohui

    2014-08-01

    Interaction between osteogenesis and angiogenesis plays an important role in implant osseointegration. In the present study we investigated the influence of titanium surface properties on the angiogenic behaviors of endothelial cells grown in direct contact co-culture with osteoblasts. Human umbilical vein endothelial cells (HUVECs) and osteoblast-like cells (MG-63 cells) were grown in direct co-culture on the following titanium surfaces: acid-etched (A), hydrophilic A (modA), coarse-gritblasted and acid-etched (SLA) and hydrophilic SLA (SLActive). Cell proliferation was evaluated by cell counting combined with flow cytometry. The expression of von Willebrand Factor (vWF), thrombomodulin (TM), endothelial cell protein C receptor (EPCR), E-Selectin, as well as vascular endothelial growth factor (VEGF) receptors Flt-1 and KDR in HUVECs and VEGF in MG-63 were measured by qPCR. The dynamic behavior of endothelial cells was recorded by time-lapse microscopy. Proliferation of HUVECs was highest on A, followed by SLA, modA and SLActive surfaces. The expression of vWF, TM, EPCR, E-Selectin and Flt-1 in HUVECs was significantly higher on A than on all other surfaces. The expression of KDR in HUVECs grown on A surface was below detection limit. VEGF expression in MG-63 cells was significantly higher on SLActive vs SLA and modA vs A surfaces. Time-lapse microscopy revealed that HUVECs moved quickest and formed cell clusters earlier on A surface, followed by SLA, modA and SLActive surface. In co-culture conditions, proliferation and expression of angiogenesis associated genes in HUVECs are promoted by smooth hydrophobic Ti surface, which is in contrast to previous mono-culture studies. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Osteopontin adsorption to Gram-positive cells reduces adhesion forces and attachment to surfaces under flow

    DEFF Research Database (Denmark)

    Kristensen, M F; Zeng, G; Neu, T R

    2017-01-01

    caries or medical device-related infections. It further investigated if OPN's effect on adhesion is caused by blocking the accessibility of glycoconjugates on bacterial surfaces. Bacterial adhesion was determined in a shear-controlled flow cell system in the presence of different concentrations of OPN......The bovine milk protein osteopontin (OPN) may be an efficient means to prevent bacterial adhesion to dental tissues and control biofilm formation. This study sought to determine to what extent OPN impacts adhesion forces and surface attachment of different bacterial strains involved in dental......, and interaction forces of single bacteria were quantified using single-cell force spectroscopy before and after OPN exposure. Moreover, the study investigated OPN's effect on the accessibility of cell surface glycoconjugates through fluorescence lectin-binding analysis. OPN strongly affected bacterial adhesion...

  10. Improvement of Polypropylene Biological Interactions by using Superhydrophobic Surface Modification

    Directory of Open Access Journals (Sweden)

    E. Shirani

    2018-03-01

    Full Text Available The significance of producing superhydrophobic surfaces through modification of surface chemistry and structure is in preventing or delaying biofilm formation. This is done to improve biocompatibility and chemical and biological properties of the surface by creating micro-nano multilevel rough structure; and to decrease surface free energy by Fault Tolerant Control Strategy (FTCS . Here, we produced a superhydrophobic surface through TiO2 coating and flurosilanization methods. Then, in order to evaluate the physicochemical properties of the modified surfaces, they were characterized by Scanning Electron Microscope (SEM, Fourier Transform Infrared Spectroscopy (FTIR, Contact Angle (CA, cell viability assay (using Hela and MCF-7 cancer cell lines as well as non-cancerous human fibroblast cells by MTT, Bovine Serum Abumin (BSA protein adsorption using Bradford and bacterial adhesion assay (Staphylococcus aureus and Staphylococcus epidermidis using microtiter. Results showed that contact angle and surface energey of superhydrophobic modified surface increased to 150° and decreased to 5.51 mj/m2, respectively due to physicochemical modifications of the surface. In addition, the results showed a substantial reduction in protein adsorption and bacterial cell adhesion in superhydrophobic surface.

  11. Elastic interaction between surface and spherical pore

    International Nuclear Information System (INIS)

    Ganeev, G.Z.; Kadyrzhanov, K.K.; Kislitsyn, S.B.; Turkebaev, T.Eh.

    2000-01-01

    The energy of elastic interaction of a gas-filled spherical cavity with a boundary of an elastic isotropic half-space is determined. The elastic field of a system of a spherical cavity - boundary is represented as an expansion in series of potential functions. The factors of expansions are determined by boundary conditions on a free surface of an elastic half-space and on a spherical surface of a cavity with pressure of gas P. Function of a Tresca-Miesesa on a surface of elastic surface is defined additionally with purpose creep condition determination caused by gas pressure in the cavity. (author)

  12. Structure and interactions of the human programmed cell death 1 receptor.

    Science.gov (United States)

    Cheng, Xiaoxiao; Veverka, Vaclav; Radhakrishnan, Anand; Waters, Lorna C; Muskett, Frederick W; Morgan, Sara H; Huo, Jiandong; Yu, Chao; Evans, Edward J; Leslie, Alasdair J; Griffiths, Meryn; Stubberfield, Colin; Griffin, Robert; Henry, Alistair J; Jansson, Andreas; Ladbury, John E; Ikemizu, Shinji; Carr, Mark D; Davis, Simon J

    2013-04-26

    PD-1, a receptor expressed by T cells, B cells, and monocytes, is a potent regulator of immune responses and a promising therapeutic target. The structure and interactions of human PD-1 are, however, incompletely characterized. We present the solution nuclear magnetic resonance (NMR)-based structure of the human PD-1 extracellular region and detailed analyses of its interactions with its ligands, PD-L1 and PD-L2. PD-1 has typical immunoglobulin superfamily topology but differs at the edge of the GFCC' sheet, which is flexible and completely lacks a C" strand. Changes in PD-1 backbone NMR signals induced by ligand binding suggest that, whereas binding is centered on the GFCC' sheet, PD-1 is engaged by its two ligands differently and in ways incompletely explained by crystal structures of mouse PD-1 · ligand complexes. The affinities of these interactions and that of PD-L1 with the costimulatory protein B7-1, measured using surface plasmon resonance, are significantly weaker than expected. The 3-4-fold greater affinity of PD-L2 versus PD-L1 for human PD-1 is principally due to the 3-fold smaller dissociation rate for PD-L2 binding. Isothermal titration calorimetry revealed that the PD-1/PD-L1 interaction is entropically driven, whereas PD-1/PD-L2 binding has a large enthalpic component. Mathematical simulations based on the biophysical data and quantitative expression data suggest an unexpectedly limited contribution of PD-L2 to PD-1 ligation during interactions of activated T cells with antigen-presenting cells. These findings provide a rigorous structural and biophysical framework for interpreting the important functions of PD-1 and reveal that potent inhibitory signaling can be initiated by weakly interacting receptors.

  13. Influence of World and Gravity Model Selection on Surface Interacting Vehicle Simulations

    Science.gov (United States)

    Madden, Michael M.

    2007-01-01

    A vehicle simulation is surface-interacting if the state of the vehicle (position, velocity, and acceleration) relative to the surface is important. Surface-interacting simulations perform ascent, entry, descent, landing, surface travel, or atmospheric flight. Modeling of gravity is an influential environmental factor for surface-interacting simulations. Gravity is the free-fall acceleration observed from a world-fixed frame that rotates with the world. Thus, gravity is the sum of gravitation and the centrifugal acceleration due to the world s rotation. In surface-interacting simulations, the fidelity of gravity at heights above the surface is more significant than gravity fidelity at locations in inertial space. A surface-interacting simulation cannot treat the gravity model separately from the world model, which simulates the motion and shape of the world. The world model's simulation of the world's rotation, or lack thereof, produces the centrifugal acceleration component of gravity. The world model s reproduction of the world's shape will produce different positions relative to the world center for a given height above the surface. These differences produce variations in the gravitation component of gravity. This paper examines the actual performance of world and gravity/gravitation pairs in a simulation using the Earth.

  14. Cell Adhesions: Actin-Based Modules that Mediate Cell-Extracellular Matrix and Cell-Cell Interactions

    Science.gov (United States)

    Bachir, Alexia; Horwitz, Alan Rick; Nelson, W. James; Bianchini, Julie M.

    2018-01-01

    Cell adhesions link cells to the extracellular matrix (ECM) and to each other, and depend on interactions with the actin cytoskeleton. Both cell-ECM and cell-cell adhesion sites contain discrete, yet overlapping functional modules. These modules establish physical association with the actin cytoskeleton, locally modulate actin organization and dynamics, and trigger intracellular signaling pathways. Interplay between these modules generates distinct actin architectures that underlie different stages, types, and functions of cell-ECM and cell-cell adhesions. Actomyosin contractility is required to generate mature, stable adhesions, as well as sense and translate the mechanical properties of the cellular environment to changes in cell organization and behavior. In this chapter we discuss the organization and function of different adhesion modules and how they interact with the actin cytoskeleton. We highlight the molecular mechanisms of mechanotransduction in adhesions, and how adhesion molecules mediate crosstalk between cell-ECM and cell-cell adhesion sites. PMID:28679638

  15. Basic Surface Properties of Mononuclear Cells from Didelphis marsupialis

    Directory of Open Access Journals (Sweden)

    Nacife Valéria Pereira

    1998-01-01

    Full Text Available The electrostatic surface charge and surface tension of mononuclear cells/monocytes obtained from young and adult marsupials (Didelphis marsupialis were investigated by using cationized ferritin and colloidal iron hydroxyde, whole cell electrophoresis, and measurements of contact angles. Anionic sites were found distributed throughout the entire investigated cell surfaces. The results revealed that the anionic character of the cells is given by electrostatic charges corresponding to -18.8 mV (cells from young animals and -29.3 mV (cells from adult animals. The surface electrostatic charge decreased from 10 to 65.2% after treatment of the cells with each one of trypsin, neuraminidase and phospholipase C. The hydrophobic nature of the mononuclear cell surfaces studied by using the contact angle method revealed that both young and adult cells possess cell surfaces of high hidrofilicity since the angles formed with drops of saline water were 42.5°and 40.8°, respectively. Treatment of the cells with trypsin or neuraminidase rendered their surfaces more hydrophobic, suggesting that sialic acid-containing glycoproteins are responsible for most of the hydrophilicity observed in the mononuclear cell surfaces from D. marsupialis.

  16. Lactoperoxidase catalyzed radioiodination of cell surface immunoglobulin: incorporated radioactivity may not reflect relative cell surface Ig density

    International Nuclear Information System (INIS)

    Wilder, R.L.; Yuen, C.C.; Mage, R.G.

    1979-01-01

    Rabbit and mouse splenic lymphocytes were radioiodinated by the lactoperoxidase technique, extracted with non-ionic detergent, immunoprecipitated with high titered rabbit anti-kappa antisera, and compared by SDS-PAGE. Mouse sIg peaks were reproducibly larger in size than rabbit sIg peaks (often greater than 10 times). Neither differences in incorporation of label into the rabbit cell surface, nor differences in average sIg density explain this result. Total TCA-precipitable radioactivity was similar in each species. Estimation of the relative amounts of sIg in the mouse and rabbit showed similar average sIg densities. Differences in detergent solubility, proteolytic lability, or antisera used also do not adequately account for this difference. Thus, these data indicate that radioactivity incorporated after lactoperoxidase catalyzed cell surface radioiodination may not reflect cell surface Ig density. Conclusions about cell surface density based upon relative incorporation of radioactivity should be confirmed by other approaches

  17. Multijunction Solar Cell Technology for Mars Surface Applications

    Science.gov (United States)

    Stella, Paul M.; Mardesich, Nick; Ewell, Richard C.; Mueller, Robert L.; Endicter, Scott; Aiken, Daniel; Edmondson, Kenneth; Fetze, Chris

    2006-01-01

    Solar cells used for Mars surface applications have been commercial space qualified AM0 optimized devices. Due to the Martian atmosphere, these cells are not optimized for the Mars surface and as a result operate at a reduced efficiency. A multi-year program, MOST (Mars Optimized Solar Cell Technology), managed by JPL and funded by NASA Code S, was initiated in 2004, to develop tools to modify commercial AM0 cells for the Mars surface solar spectrum and to fabricate Mars optimized devices for verification. This effort required defining the surface incident spectrum, developing an appropriate laboratory solar simulator measurement capability, and to develop and test commercial cells modified for the Mars surface spectrum. This paper discusses the program, including results for the initial modified cells. Simulated Mars surface measurements of MER cells and Phoenix Lander cells (2007 launch) are provided to characterize the performance loss for those missions. In addition, the performance of the MER rover solar arrays is updated to reflect their more than two (2) year operation.

  18. Interactions between nano-TiO2 and the oral cavity: impact of nanomaterial surface hydrophilicity/hydrophobicity.

    Science.gov (United States)

    Teubl, Birgit J; Schimpel, Christa; Leitinger, Gerd; Bauer, Bettina; Fröhlich, Eleonore; Zimmer, Andreas; Roblegg, Eva

    2015-04-09

    Titanium dioxide (TiO2) nanoparticles are available in a variety of oral applications, such as food additives and cosmetic products. Thus, questions about their potential impact on the oro-gastrointestinal route rise. The oral cavity represents the first portal of entry and is known to rapidly interact with nanoparticles. Surface charge and size contribute actively to the particle-cell interactions, but the influence of surface hydrophilicity/hydrophobicity has never been shown before. This study addresses the biological impact of hydrophilic (NM 103, rutile, 20 nm) and hydrophobic (NM 104, rutile, 20 nm) TiO2 particles within the buccal mucosa. Particle characterization was addressed with dynamic light scattering and laser diffraction. Despite a high agglomeration tendency, 10% of the particles/agglomerates were present in the nanosized range and penetrated into the mucosa, independent of the surface properties. However, significant differences were observed in intracellular particle localization. NM 104 particles were found freely distributed in the cytoplasm, whereas their hydrophobic counterparts were engulfed in vesicular structures. Although cell viability/membrane integrity was not affected negatively, screening assays demonstrated that NM 104 particles showed a higher potential to decrease the physiological mitochondrial membrane potential than NM 103, resulting in a pronounced generation of reactive oxygen species. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Sikorsky interactive graphics surface design/manufacturing system

    Science.gov (United States)

    Robbins, R.

    1975-01-01

    An interactive graphics system conceived to be used in the design, analysis, and manufacturing of aircraft components with free form surfaces was described. In addition to the basic surface definition and viewing capabilities inherent in such a system, numerous other features are present: surface editing, automated smoothing of control curves, variable milling patch boundary definitions, surface intersection definition and viewing, automatic creation of true offset surfaces, digitizer and drafting machine interfaces, and cutter path optimization. Documented costs and time savings of better than six to one are being realized with this system. The system was written in FORTRAN and GSP for use on IBM 2250 CRT's in conjunction with an IBM 370/158 computer.

  20. Improving surface acousto-optical interaction by high aspect ratio electrodes

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2009-01-01

    The acousto-optical interaction of an optical wave confined inside a waveguide and a surface acoustic wave launched by an interdigital transducer (IDT) at the surface of a piezoelectric material is considered. The IDT with high aspect ratio electrodes supports several acoustic modes that are stro......The acousto-optical interaction of an optical wave confined inside a waveguide and a surface acoustic wave launched by an interdigital transducer (IDT) at the surface of a piezoelectric material is considered. The IDT with high aspect ratio electrodes supports several acoustic modes...

  1. Anomalous water dynamics at surfaces and interfaces: synergistic effects of confinement and surface interactions

    Science.gov (United States)

    Biswas, Rajib; Bagchi, Biman

    2018-01-01

    In nature, water is often found in contact with surfaces that are extended on the scale of molecule size but small on a macroscopic scale. Examples include lipid bilayers and reverse micelles as well as biomolecules like proteins, DNA and zeolites, to name a few. While the presence of surfaces and interfaces interrupts the continuous hydrogen bond network of liquid water, confinement on a mesoscopic scale introduces new features. Even when extended on a molecular scale, natural and biological surfaces often have features (like charge, hydrophobicity) that vary on the scale of the molecular diameter of water. As a result, many new and exotic features, which are not seen in the bulk, appear in the dynamics of water close to the surface. These different behaviors bear the signature of both water-surface interactions and of confinement. In other words, the altered properties are the result of the synergistic effects of surface-water interactions and confinement. Ultrafast spectroscopy, theoretical modeling and computer simulations together form powerful synergistic approaches towards an understanding of the properties of confined water in such systems as nanocavities, reverse micelles (RMs), water inside and outside biomolecules like proteins and DNA, and also between two hydrophobic walls. We shall review the experimental results and place them in the context of theory and simulations. For water confined within RMs, we discuss the possible interference effects propagating from opposite surfaces. Similar interference is found to give rise to an effective attractive force between two hydrophobic surfaces immersed and kept fixed at a separation of d, with the force showing an exponential dependence on this distance. For protein and DNA hydration, we shall examine a multitude of timescales that arise from frustration effects due to the inherent heterogeneity of these surfaces. We pay particular attention to the role of orientational correlations and modification of the

  2. Jet-Surface Interaction - High Aspect Ratio Nozzle Test: Test Summary

    Science.gov (United States)

    Brown, Clifford A.

    2016-01-01

    The Jet-Surface Interaction High Aspect Ratio Nozzle Test was conducted in the Aero-Acoustic Propulsion Laboratory at the NASA Glenn Research Center in the fall of 2015. There were four primary goals specified for this test: (1) extend the current noise database for rectangular nozzles to higher aspect ratios, (2) verify data previously acquired at small-scale with data from a larger model, (3) acquired jet-surface interaction noise data suitable for creating verifying empirical noise models and (4) investigate the effect of nozzle septa on the jet-mixing and jet-surface interaction noise. These slides give a summary of the test with representative results for each goal.

  3. Functional Elements on SIRPα IgV domain Mediate Cell Surface Binding to CD47

    OpenAIRE

    Liu, Yuan; Tong, Qiao; Zhou, Yubin; Lee, Hsiau-Wei; Yang, Jenny J.; Bühring, Hans-Jörg; Chen, Yi-Tien; Ha, Binh; Chen, Celia X-J.; Zen, Ke

    2006-01-01

    SIRPα and SIRPβ1, the two major isoforms of the signal regulatory protein (SIRP) family, are co-expressed in human leukocytes but mediate distinct extracellular binding interactions and divergent cell signaling responses. Previous studies have demonstrated that binding of SIRPα with CD47, another important cell surface molecule, through the extracellular IgV domain regulates important leukocyte functions including macrophage recognition, leukocyte adhesion and transmigration. Although SIRPβ1 ...

  4. Effects of pre- and post-electrospinning plasma treatments on electrospun PCL nanofibers to improve cell interactions

    International Nuclear Information System (INIS)

    Asadian, M; Grande, S; Morent, R; Nikiforov, A; De Geyter, N; Declercq, H

    2017-01-01

    In this study, liquid plasma treatment was used to improve the morphology of Poly-ε-CaproLactone (PCL) NanoFibers (NFs), followed by performing a Dielectric Barrier Discharge (DBD) plasma surface modification to enhance the hydrophilicity of electrospun mats generated from plasma-modified PCL solutions. Cell interaction studies performed after 1 day and 7 days clearly revealed the highly increased cellular interactions on the double plasma-treated nanofibers compared to the pristine ones due to the combination of (1) a better NF morphology and (2) an increased surface hydrophilicity. (paper)

  5. Atmosphere-surface interactions over polar oceans and heterogeneous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Vihma, T.

    1995-12-31

    Processes of interaction between the atmospheric boundary layer and the planetary surface have been studied with special emphasis on polar ocean surfaces: the open ocean, leads, polynyas and sea ice. The local exchange of momentum, heat and moisture has been studied experimentally both in the Weddell Sea and in the Greenland Sea. Exchange processes over heterogeneous surfaces are addressed by modelling studies. Over a homogeneous surface, the local turbulent fluxes can be reasonably well estimated using an iterative flux-profile scheme based on the Monin-Obukhov similarity theory. In the Greenland Sea, the near-surface air temperature and the generally small turbulent fluxes over the open ocean were affected by the sea surface temperature fronts. Over the sea ice cover in the Weddell Sea, the turbulent sensible heat flux was generally downwards, and together with an upward oceanic heat flux through the ice it compensated the heat loss from the surface via long-wave radiation. The wind dominated on time scales of days, while the current became important on longer time scales. The drift dynamics showed apparent spatial differences between the eastern and western regions, as well as between the Antarctic Circumpolar Current and the rest of the Weddell Sea. Inertial motion was present in regions of low ice concentration. The surface heterogeneity, arising e.g. from roughness or temperature distribution, poses a problem for the parameterization of surface exchange processes in large-scale models. In the case of neutral flow over a heterogeneous terrain, an effective roughness length can be used to parameterize the roughness effects

  6. Atmosphere-surface interactions over polar oceans and heterogeneous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Vihma, T

    1996-12-31

    Processes of interaction between the atmospheric boundary layer and the planetary surface have been studied with special emphasis on polar ocean surfaces: the open ocean, leads, polynyas and sea ice. The local exchange of momentum, heat and moisture has been studied experimentally both in the Weddell Sea and in the Greenland Sea. Exchange processes over heterogeneous surfaces are addressed by modelling studies. Over a homogeneous surface, the local turbulent fluxes can be reasonably well estimated using an iterative flux-profile scheme based on the Monin-Obukhov similarity theory. In the Greenland Sea, the near-surface air temperature and the generally small turbulent fluxes over the open ocean were affected by the sea surface temperature fronts. Over the sea ice cover in the Weddell Sea, the turbulent sensible heat flux was generally downwards, and together with an upward oceanic heat flux through the ice it compensated the heat loss from the surface via long-wave radiation. The wind dominated on time scales of days, while the current became important on longer time scales. The drift dynamics showed apparent spatial differences between the eastern and western regions, as well as between the Antarctic Circumpolar Current and the rest of the Weddell Sea. Inertial motion was present in regions of low ice concentration. The surface heterogeneity, arising e.g. from roughness or temperature distribution, poses a problem for the parameterization of surface exchange processes in large-scale models. In the case of neutral flow over a heterogeneous terrain, an effective roughness length can be used to parameterize the roughness effects

  7. Interaction of energetic particles with polymer surfaces: surface morphology development and sputtered polymer-fragment ion analysis

    International Nuclear Information System (INIS)

    Michael, R.S.

    1987-01-01

    The core of this thesis is based on a series of papers that have been published or will soon be published in which the various processes taking place in the energetic particle-polymer surface interaction scene is investigated. Results presented show different developments on polymer surfaces when compared to the vast experimental data on energetic particle-metal surface interactions. The surface morphology development depends on the physical characteristics of the polymer. Sputtering yields of fluoropolymers were several orders higher than the sputtering yields of aliphatic and aromatic polymers. Depending on the chemical nature of the polymer, the surface morphology development was dependent upon the extent of radiation-damage accumulation. Fast Atom Bombardment Mass Spectrometry at low and high resolution was applied to the characterization of sputtered polymer fragment ions. Fragment ions and their intensities were used to identify polymer samples, observe radiation damage accumulation and probe polymer-polymer interface of a polymer-polymer sandwich structure. A model was proposed which attempts to explain the nature of processes involved in the energetic particle-polymer surface interaction region

  8. Cell-cell interactions mediate cytoskeleton organization and collective endothelial cell chemotaxis.

    Science.gov (United States)

    Shamloo, Amir

    2014-09-01

    This study investigates the role of cell-cell and cell-ligand interactions in cytoskeleton organization of endothelial cells (ECs) and their directional migration within a microfluidic device. The migration of ECs in response to a biochemical factor was studied. Mathematical analysis of the cell migration pathways and cellular cytoskeleton revealed that directional migration, migration persistence length, migration speed, and cytoskeletal stress fiber alignment can be mediated by the level of cell contacts as well as the presence or absence of a biochemical polarizing factor. It was shown that in the presence of a biochemical polarizing factor, higher cell density and more frequent cell contacts has a reinforcing effect on collective cell chemotaxis. In contrast, in the absence of a polarizing factor, high cell density can decrease or suppress the ability of the cells to migrate. Also, the correlation of actin stress fiber organization and alignment with directional migration of ECs was investigated. It was shown that in the presence of a biochemical polarizing factor, stress fibers within the cytoskeleton of ECs can be significantly aligned parallel to the gradient direction when the cells have higher level of contacts. The results also show that the organization and alignment of actin stress fibers is mediated by cell adhesion junctions during collective cell migration and introduce cell-cell interactions as a key factor during collective cell chemotaxis. © 2014 Wiley Periodicals, Inc.

  9. Protein-surface interactions on stimuli-responsive polymeric biomaterials.

    Science.gov (United States)

    Cross, Michael C; Toomey, Ryan G; Gallant, Nathan D

    2016-03-04

    Responsive surfaces: a review of the dependence of protein adsorption on the reversible volume phase transition in stimuli-responsive polymers. Specifically addressed are a widely studied subset: thermoresponsive polymers. Findings are also generalizable to other materials which undergo a similarly reversible volume phase transition. As of 2015, over 100,000 articles have been published on stimuli-responsive polymers and many more on protein-biomaterial interactions. Significantly, fewer than 100 of these have focused specifically on protein interactions with stimuli-responsive polymers. These report a clear trend of increased protein adsorption in the collapsed state compared to the swollen state. This control over protein interactions makes stimuli-responsive polymers highly useful in biomedical applications such as wound repair scaffolds, on-demand drug delivery, and antifouling surfaces. Outstanding questions are whether the protein adsorption is reversible with the volume phase transition and whether there is a time-dependence. A clear understanding of protein interactions with stimuli-responsive polymers will advance theoretical models, experimental results, and biomedical applications.

  10. Cell Surface Proteome of Dental Pulp Stem Cells Identified by Label-Free Mass Spectrometry.

    Directory of Open Access Journals (Sweden)

    Christian Niehage

    Full Text Available Multipotent mesenchymal stromal cells (MSCs are promising tools for regenerative medicine. They can be isolated from different sources based on their plastic-adherence property. The identification of reliable cell surface markers thus becomes the Holy Grail for their prospective isolation. Here, we determine the cell surface proteomes of human dental pulp-derived MSCs isolated from single donors after culture expansion in low (2% or high (10% serum-containing media. Cell surface proteins were tagged on intact cells using cell impermeable, cleavable sulfo-NHS-SS-biotin, which allows their enrichment by streptavidin pull-down. For the proteomic analyses, we first compared label-free methods to analyze cell surface proteomes i.e. composition, enrichment and proteomic differences, and we developed a new mathematical model to determine cell surface protein enrichment using a combinatorial gene ontology query. Using this workflow, we identified 101 cluster of differentiation (CD markers and 286 non-CD cell surface proteins. Based on this proteome profiling, we identified 14 cell surface proteins, which varied consistently in abundance when cells were cultured under low or high serum conditions. Collectively, our analytical methods provide a basis for identifying the cell surface proteome of dental pulp stem cells isolated from single donors and its evolution during culture or differentiation. Our data provide a comprehensive cell surface proteome for the precise identification of dental pulp-derived MSC populations and their isolation for potential therapeutic intervention.

  11. In silico characterization of cell-cell interactions using a cellular automata model of cell culture.

    Science.gov (United States)

    Kihara, Takanori; Kashitani, Kosuke; Miyake, Jun

    2017-07-14

    Cell proliferation is a key characteristic of eukaryotic cells. During cell proliferation, cells interact with each other. In this study, we developed a cellular automata model to estimate cell-cell interactions using experimentally obtained images of cultured cells. We used four types of cells; HeLa cells, human osteosarcoma (HOS) cells, rat mesenchymal stem cells (MSCs), and rat smooth muscle A7r5 cells. These cells were cultured and stained daily. The obtained cell images were binarized and clipped into squares containing about 10 4 cells. These cells showed characteristic cell proliferation patterns. The growth curves of these cells were generated from the cell proliferation images and we determined the doubling time of these cells from the growth curves. We developed a simple cellular automata system with an easily accessible graphical user interface. This system has five variable parameters, namely, initial cell number, doubling time, motility, cell-cell adhesion, and cell-cell contact inhibition (of proliferation). Within these parameters, we obtained initial cell numbers and doubling times experimentally. We set the motility at a constant value because the effect of the parameter for our simulation was restricted. Therefore, we simulated cell proliferation behavior with cell-cell adhesion and cell-cell contact inhibition as variables. By comparing growth curves and proliferation cell images, we succeeded in determining the cell-cell interaction properties of each cell. Simulated HeLa and HOS cells exhibited low cell-cell adhesion and weak cell-cell contact inhibition. Simulated MSCs exhibited high cell-cell adhesion and positive cell-cell contact inhibition. Simulated A7r5 cells exhibited low cell-cell adhesion and strong cell-cell contact inhibition. These simulated results correlated with the experimental growth curves and proliferation images. Our simulation approach is an easy method for evaluating the cell-cell interaction properties of cells.

  12. Subcellular distribution of uranium in the roots of Spirodela punctata and surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Xiaoqin, E-mail: xiaoqin_nie@163.com [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China); Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Dong, Faqin, E-mail: fqdong2004@163.com [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China); Liu, Ning [Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Liu, Mingxue [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China); Zhang, Dong; Kang, Wu [Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics, Mianyang 621900 (China); Sun, Shiyong; Zhang, Wei; Yang, Jie [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China)

    2015-08-30

    Graphical abstract: - Highlights: • The proportion of uranium concentration approximate as 8:2:1 in the cell wall organelle and cytosol fractions of roots of S. punctata. • The particles including 35% Fe (wt%) released from the cells after 100 mg/L U treatment 48 h. • Most of the uranium bound onto the root surface and contacted with phosphorus ligands and formed as nano-scales U-P lamellar crystal. • FTIR and XPS analyses result indicates the uranium changed the band position and shapes of phosphate group, and the region of characteristic peak belongs to U(VI) and U(IV) were also observed. - Abstract: The subcellular distribution of uranium in roots of Spirodela punctata (duckweed) and the process of surface interaction were studied upon exposure to U (0, 5–200 mg/L) at pH 5. The concentration of uranium in each subcelluar fraction increased significantly with increasing solution U level, after 200 mg/L uranium solution treatment 120 h, the proportion of uranium concentration approximate as 8:2:1 in the cell wall organelle and cytosol fractions of roots of S. punctata. OM SEM and EDS showed after 5–200 mg/L U treatment 4–24 h, some intracellular fluid released from the root cells, after 100 mg/L U treatment 48 h, the particles including 35% Fe (wt%) and other organic matters such as EPS released from the cells, most of the uranium bound onto the root surface and contacted with phosphorus ligands and formed as nano-scales U-P lamellar crystal, similar crystal has been found in the cell wall and organelle fractions after 50 mg/L U treatment 120 h. FTIR and XPS analyses result indicates the uranium changed the band position and shapes of phosphate group, and the region of characteristic peak belongs to U(VI) and U(IV) were also observed.

  13. The Role of Hydrophobicity and Surface Receptors at Hyphae of Lyophyllum sp. Strain Karsten in the Interaction with Burkholderia terrae BS001 – Implications for Interactions in Soil

    Science.gov (United States)

    Vila, Taissa; Nazir, Rashid; Rozental, Sonia; dos Santos, Giulia M. P.; Calixto, Renata O. R.; Barreto-Bergter, Eliana; Wick, Lukas Y.; van Elsas, Jan Dirk

    2016-01-01

    The soil bacterium Burkholderia terrae strain BS001 can interact with varying soil fungi, using mechanisms that range from the utilization of carbon/energy sources such as glycerol to the ability to reach novel territories in soil via co-migration with growing fungal mycelia. Here, we investigate the intrinsic properties of the B. terrae BS001 interaction with the basidiomycetous soil fungus Lyophyllum sp. strain Karsten. In some experiments, the ascomycetous Trichoderma asperellum 302 was also used. The hyphae of Lyophyllum sp. strain Karsten were largely hydrophilic on water-containing media versus hydrophobic when aerial, as evidenced by contact angle analyses (CA). Co-migration of B. terrae strain BS001 cells with the hyphae of the two fungi occurred preferentially along the - presumably hydrophilic - soil-dwelling hyphae, whereas aerial hyphae did not allow efficient migration, due to reduced thickness of their surrounding mucous films. Moreover, the cell numbers over the length of the hyphae in soil showed an uneven distribution, i.e., the CFU numbers increased from minima at the inoculation point to maximal numbers in the middle of the extended hyphae, then decreasing toward the terminal side. Microscopic analyses of the strain BS001 associations with the Lyophyllum sp. strain Karsten hyphae in the microcosms confirmed the presence of B. terrae BS001 cells on the mucous matter that was present at the hyphal surfaces of the fungi used. Cell agglomerates were found to accumulate at defined sites on the hyphal surfaces, which were coined ‘fungal-interactive’ hot spots. Evidence was further obtained for the contention that receptors for a physical bacterium-fungus interaction occur at the Lyophyllum sp. strain Karsten hyphal surface, in which the specific glycosphingolipid ceramide monohexoside (CMH) plays an important role. Thus, bacterial adherence may be mediated by heterogeneously distributed fungal-specific receptors, implying the CMH moieties. This

  14. Construction of Hydrophobic Wood Surface and Mechanical Property of Wood Cell Wall on Nanoscale Modified by Dimethyldichlorosilane

    Science.gov (United States)

    Yang, Rui; Wang, Siqun; Zhou, Dingguo; Zhang, Jie; Lan, Ping; Jia, Chong

    2018-01-01

    Dimethyldichlorosilane was used to improve the hydrophobicity of wood surface. The water contact angle of the treated wood surface increased from 85° to 143°, which indicated increased hydrophobicity. The nanomechanical properties of the wood cell wall were evaluated using a nanoindentation test to analyse the hydrophobic mechanism on the nano scale. The elastic modulus of the cell wall was significantly affected by the concentration but the influence of treatment time is insignificant. The hardness of the cell wall for treated samples was significantly affected by both treatment time and concentration. The interaction between treatment time and concentration was extremely significant for the elastic modulus of the wood cell wall.

  15. Interaction of oxygen with zirconia surface

    International Nuclear Information System (INIS)

    Ivankiv, L.I.; Ketsman, I.V.

    1999-01-01

    The influence of surface heat treatment, electron (50-800) eV irradiation and UV (180-300) nM illumination of adsorption system on the state of oxygen adsorbed on zirconia surface have been investigated. On the basis of experimental results obtained by investigation of photon emission accompanying oxygen adsorption (AL) and TPD data existence of adsorption sites on the surface is suggested on which irreversible dissociative adsorption of oxygen occurs. These very sites are associated with emission processes Conclusion is made that the only type of adsorption sites connected with anion vacancy is present on zirconia surface and this is its charge state that determines the state of adsorbed oxygen. One of the important mechanisms by which the electron and UV photon excitation affects the adsorption interaction is the change of the charge state of the adsorption site

  16. Secondary structure of cell-penetrating peptides during interaction with fungal cells.

    Science.gov (United States)

    Gong, Zifan; Ikonomova, Svetlana P; Karlsson, Amy J

    2018-03-01

    Cell-penetrating peptides (CPPs) are peptides that cross cell membranes, either alone or while carrying molecular cargo. Although their interactions with mammalian cells have been widely studied, much less is known about their interactions with fungal cells, particularly at the biophysical level. We analyzed the interactions of seven CPPs (penetratin, Pep-1, MPG, pVEC, TP-10, MAP, and cecropin B) with the fungal pathogen Candida albicans using experiments and molecular simulations. Circular dichroism (CD) of the peptides revealed a structural transition from a random coil or weak helix to an α-helix occurs for all peptides when the solvent is changed from aqueous to hydrophobic. However, CD performed in the presence of C. albicans cells showed that proximity to the cell membrane is not necessarily sufficient to induce this structural transition, as penetratin, Pep-1, and MPG did not display a structural shift in the presence of cells. Monte Carlo simulations were performed to further probe the molecular-level interaction with the cell membrane, and these simulations suggested that pVEC, TP-10, MAP, and cecropin B strongly penetrate into the hydrophobic domain of the membrane lipid bilayer, inducing a transition to an α-helical conformation. In contrast, penetratin, Pep-1 and MPG remained in the hydrophilic region without a shift in conformation. The experimental data and MC simulations combine to explain how peptide structure affects their interaction with cells and their mechanism of translocation into cells (direct translocation vs. endocytosis). Our work also highlights the utility of combining biophysical experiments, biological experiments, and molecular modeling to understand biological phenomena. © 2017 The Protein Society.

  17. Cell behavior related to implant surfaces with different microstructure and chemical composition: an in vitro analysis.

    Science.gov (United States)

    Conserva, Enrico; Lanuti, Anna; Menini, Maria

    2010-01-01

    This paper reports on an in vitro comparison of osteoblast and mesenchymal stem cell (MSC) adhesion, proliferation, and differentiation related to two different surface treatments applied to the same implant design to determine whether the interaction between cells and implants is influenced by surface structure and chemical composition of the implants. Thirty-nine implants with a sandblasted (SB) surface and 39 implants with a grit-blasted and high-temperature acid-etched (GBAE) surface were used. The implant macrostructures and microstructures were analyzed by high- and low-voltage scanning electron microscopy (SEM) and by stereo-SEM. The surface chemical composition was investigated by energy dispersive analysis and x-ray photoemission spectroscopy. SaOS-2 osteoblasts and human MSCs were used for the evaluation of cell proliferation and alkaline phosphatase enzymatic activity in contact with the two surfaces. The GBAE surface showed fewer contaminants and a very high percentage of titanium (19.7%) compared to the SB surface (14.2%). The two surfaces showed similar mean roughness (Ra), but the depth (Rz) and density (RSm) of the porosity were significantly increased in the GBAE surface. The GBAE surface presented more osteoblast and MSC proliferation than the SB surface. No statistically significant differences in alkaline phosphatase activity were found between surfaces for either cellular line. The GBAE surface showed less surface contaminants and a higher percentage of titanium (19.7%) than the SB surface. The macro/micropore structured design and chemical composition of the GBAE surface allowed greater cell adhesion and proliferation and an earlier cell spreading but did not play an obvious role in in vitro cellular differentiation.

  18. Dual-responsive surfaces modified with phenylboronic acid-containing polymer brush to reversibly capture and release cancer cells.

    Science.gov (United States)

    Liu, Hongliang; Li, Yingying; Sun, Kang; Fan, Junbing; Zhang, Pengchao; Meng, Jingxin; Wang, Shutao; Jiang, Lei

    2013-05-22

    Artificial stimuli-responsive surfaces that can mimic the dynamic function of living systems have attracted much attention. However, there exist few artificial systems capable of responding to dual- or multistimulation as the natural system does. Herein, we synthesize a pH and glucose dual-responsive surface by grafting poly(acrylamidophenylboronic acid) (polyAAPBA) brush from aligned silicon nanowire (SiNW) array. The as-prepared surface can reversibly capture and release targeted cancer cells by precisely controlling pH and glucose concentration, exhibiting dual-responsive AND logic. In the presence of 70 mM glucose, the surface is pH responsive, which can vary from a cell-adhesive state to a cell-repulsive state by changing the pH from 6.8 to 7.8. While keeping the pH at 7.8, the surface becomes glucose responsive--capturing cells in the absence of glucose and releasing cells by adding 70 mM glucose. Through simultaneously changing the pH and glucose concentration from pH 6.8/0 mM glucose to pH 7.8/70 mM glucose, the surface is dual responsive with the capability to switch between cell capture and release for at least 5 cycles. The cell capture and release process on this dual-responsive surface is noninvasive with cell viability higher than 95%. Moreover, topographical interaction between the aligned SiNW array and cell protrusions greatly amplifies the responsiveness and accelerates the response rate of the dual-responsive surface between cell capture and release. The responsive mechanism of the dual-responsive surface is systematically studied using a quartz crystal microbalance, which shows that the competitive binding between polyAAPBA/sialic acid and polyAAPBA/glucose contributes to the dual response. Such dual-responsive surface can significantly impact biomedical and biological applications including cell-based diagnostics, in vivo drug delivery, etc.

  19. Enhanced cell disruption strategy in the release of recombinant hepatitis B surface antigen from Pichia pastoris using response surface methodology

    Science.gov (United States)

    2012-01-01

    Background Cell disruption strategies by high pressure homogenizer for the release of recombinant Hepatitis B surface antigen (HBsAg) from Pichia pastoris expression cells were optimized using response surface methodology (RSM) based on the central composite design (CCD). The factors studied include number of passes, biomass concentration and pulse pressure. Polynomial models were used to correlate the above mentioned factors to project the cell disruption capability and specific protein release of HBsAg from P. pastoris cells. Results The proposed cell disruption strategy consisted of a number of passes set at 20 times, biomass concentration of 7.70 g/L of dry cell weight (DCW) and pulse pressure at 1,029 bar. The optimized cell disruption strategy was shown to increase cell disruption efficiency by 2-fold and 4-fold for specific protein release of HBsAg when compared to glass bead method yielding 75.68% cell disruption rate (CDR) and HBsAg concentration of 29.20 mg/L respectively. Conclusions The model equation generated from RSM on cell disruption of P. pastoris was found adequate to determine the significant factors and its interactions among the process variables and the optimum conditions in releasing HBsAg when validated against a glass bead cell disruption method. The findings from the study can open up a promising strategy for better recovery of HBsAg recombinant protein during downstream processing. PMID:23039947

  20. Self assembled temperature responsive surfaces for generation of cell patches for bone tissue engineering

    International Nuclear Information System (INIS)

    Valmikinathan, Chandra M; ChangWei; Xu Jiahua; Yu Xiaojun

    2012-01-01

    One of the major challenges in the fabrication of tissue engineered scaffolds is the ability of the scaffold to biologically mimic autograft-like tissues. One of the alternate approaches to achieve this is by the application of cell seeded scaffolds with optimal porosity and mechanical properties. However, the current approaches for seeding cells on scaffolds are not optimal in terms of seeding efficiencies, cell penetration into the scaffold and more importantly uniform distribution of cells on the scaffold. Also, recent developments in scaffold geometries to enhance surface areas, pore sizes and porosities tend to further complicate the scenario. Cell sheet-based approaches for cell seeding have demonstrated a successful approach to generate scaffold-free tissue engineering approaches. However, the method of generating the temperature responsive surface is quite challenging and requires carcinogenic reagents and gamma rays. Therefore, here, we have developed temperature responsive substrates by layer-by-layer self assembly of smart polymers. Multilayer thin films prepared from tannic acid and poly N-isopropylacrylamide were fabricated based on their electrostatic and hydrogen bonding interactions. Cell attachment and proliferation studies on these thin films showed uniform cell attachment on the substrate, matching tissue culture plates. Also, the cells could be harvested as cell patches and sheets from the scaffolds, by reducing the temperature for a short period of time, and seeded onto porous scaffolds for tissue engineering applications. An enhanced cell seeding efficiency on scaffolds was observed using the cell patch-based technique as compared to seeding cells in suspension. Owing to the already pre-existent cell–cell and cell–extracellular matrix interactions, the cell patch showed the ability to reattach rapidly onto scaffolds and showed enhanced ability to proliferate and differentiate into a bone-like matrix. (paper)

  1. Synergistic interactions of blood-borne immune cells, fibroblasts and extracellular matrix drive repair in an in vitro peri-implant wound healing model

    Science.gov (United States)

    Burkhardt, Melanie A.; Waser, Jasmin; Milleret, Vincent; Gerber, Isabel; Emmert, Maximilian Y.; Foolen, Jasper; Hoerstrup, Simon P.; Schlottig, Falko; Vogel, Viola

    2016-02-01

    Low correlations of cell culture data with clinical outcomes pose major medical challenges with costly consequences. While the majority of biomaterials are tested using in vitro cell monocultures, the importance of synergistic interactions between different cell types on paracrine signalling has recently been highlighted. In this proof-of-concept study, we asked whether the first contact of surfaces with whole human blood could steer the tissue healing response. This hypothesis was tested using alkali-treatment of rough titanium (Ti) surfaces since they have clinically been shown to improve early implant integration and stability, yet blood-free in vitro cell cultures poorly correlated with in vivo tissue healing. We show that alkali-treatment, compared to native Ti surfaces, increased blood clot thickness, including platelet adhesion. Strikingly, blood clots with entrapped blood cells in synergistic interactions with fibroblasts, but not fibroblasts alone, upregulated the secretion of major factors associated with fast healing. This includes matrix metalloproteinases (MMPs) to break down extracellular matrix and the growth factor VEGF, known for its angiogenic potential. Consequently, in vitro test platforms, which consider whole blood-implant interactions, might be superior in predicting wound healing in response to biomaterial properties.

  2. XIX Conference on Plasma Surface Interactions

    International Nuclear Information System (INIS)

    Kurnaev, V A; Gasparyan, Yu M

    2016-01-01

    The 19 th Conference on Plasma Surface Interactions (PSI-2016) was held at National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) on 28-29 January 2016. This is a traditional annual meeting organized by MEPhI for many years and devoted to the recent achievements of Russian scientists and foreign colleagues in experimental and computer simulations of plasma and its components' interactions with plasma faced materials (PFM) for fusion devices and plasma technologies. The conference agenda covered a broad list of topics including: • plasma induced erosion and modification of materials; • radiation damage in materials; • lithium and liquid metals as PFM; • modeling of plasma surface interaction and processes in SOL of tokamak plasma; • diagnostics of plasma-surface interaction. The aim of the conference was to present and discuss new results in PSI in a wide audience with different areas of expertise. The important feature of the conference is to give PhD and undergraduate students the opportunity for approbation of results of their scientific activity and improve their knowledge in the novel directions of R and D in the field of fusion and plasma technologies. In total, more than 80 experienced and young researchers participated in the conference. These Proceedings contain 21 papers selected for publication, which were reviewed by the invited international team of editors (T. Tanabe, S. Petrovich, Ch. Grisolia, Yu. Martynenko, S. Krasheninnikov, L. Begrambekov, A. Pisarev). The Conference as well as editing of this issue were supported by National Research Nuclear University MEPhI in the framework of the Russian Academic Excellence Project (contract No. 02.a03.21.0005, 27.08.2013). Finally, we would like to thank all of the speakers, participants and organizing committee members for their contribution to the conference. Acknowledgements The organizers of the conference would like to thank for the support from National Research

  3. Protein-protein interaction site predictions with three-dimensional probability distributions of interacting atoms on protein surfaces.

    Directory of Open Access Journals (Sweden)

    Ching-Tai Chen

    Full Text Available Protein-protein interactions are key to many biological processes. Computational methodologies devised to predict protein-protein interaction (PPI sites on protein surfaces are important tools in providing insights into the biological functions of proteins and in developing therapeutics targeting the protein-protein interaction sites. One of the general features of PPI sites is that the core regions from the two interacting protein surfaces are complementary to each other, similar to the interior of proteins in packing density and in the physicochemical nature of the amino acid composition. In this work, we simulated the physicochemical complementarities by constructing three-dimensional probability density maps of non-covalent interacting atoms on the protein surfaces. The interacting probabilities were derived from the interior of known structures. Machine learning algorithms were applied to learn the characteristic patterns of the probability density maps specific to the PPI sites. The trained predictors for PPI sites were cross-validated with the training cases (consisting of 432 proteins and were tested on an independent dataset (consisting of 142 proteins. The residue-based Matthews correlation coefficient for the independent test set was 0.423; the accuracy, precision, sensitivity, specificity were 0.753, 0.519, 0.677, and 0.779 respectively. The benchmark results indicate that the optimized machine learning models are among the best predictors in identifying PPI sites on protein surfaces. In particular, the PPI site prediction accuracy increases with increasing size of the PPI site and with increasing hydrophobicity in amino acid composition of the PPI interface; the core interface regions are more likely to be recognized with high prediction confidence. The results indicate that the physicochemical complementarity patterns on protein surfaces are important determinants in PPIs, and a substantial portion of the PPI sites can be predicted

  4. Protein-Protein Interaction Site Predictions with Three-Dimensional Probability Distributions of Interacting Atoms on Protein Surfaces

    Science.gov (United States)

    Chen, Ching-Tai; Peng, Hung-Pin; Jian, Jhih-Wei; Tsai, Keng-Chang; Chang, Jeng-Yih; Yang, Ei-Wen; Chen, Jun-Bo; Ho, Shinn-Ying; Hsu, Wen-Lian; Yang, An-Suei

    2012-01-01

    Protein-protein interactions are key to many biological processes. Computational methodologies devised to predict protein-protein interaction (PPI) sites on protein surfaces are important tools in providing insights into the biological functions of proteins and in developing therapeutics targeting the protein-protein interaction sites. One of the general features of PPI sites is that the core regions from the two interacting protein surfaces are complementary to each other, similar to the interior of proteins in packing density and in the physicochemical nature of the amino acid composition. In this work, we simulated the physicochemical complementarities by constructing three-dimensional probability density maps of non-covalent interacting atoms on the protein surfaces. The interacting probabilities were derived from the interior of known structures. Machine learning algorithms were applied to learn the characteristic patterns of the probability density maps specific to the PPI sites. The trained predictors for PPI sites were cross-validated with the training cases (consisting of 432 proteins) and were tested on an independent dataset (consisting of 142 proteins). The residue-based Matthews correlation coefficient for the independent test set was 0.423; the accuracy, precision, sensitivity, specificity were 0.753, 0.519, 0.677, and 0.779 respectively. The benchmark results indicate that the optimized machine learning models are among the best predictors in identifying PPI sites on protein surfaces. In particular, the PPI site prediction accuracy increases with increasing size of the PPI site and with increasing hydrophobicity in amino acid composition of the PPI interface; the core interface regions are more likely to be recognized with high prediction confidence. The results indicate that the physicochemical complementarity patterns on protein surfaces are important determinants in PPIs, and a substantial portion of the PPI sites can be predicted correctly with

  5. Cell surface of sea urchin micromeres and primary mesenchyme

    International Nuclear Information System (INIS)

    DeSimone, D.W.

    1985-01-01

    The cell surface and extracellular matrix (ECM) of the sea urchin embryo were studied during the early morphogenetic events involved in the differentiation of the micromere cell lineage. Sixteen-cell and early cleavage stage blastomeres were isolated and the protein composition of their cell surfaces examined by 125 I-labelling followed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Micromere-specific cell surface proteins are reported for Arbacia punctulata, Strongylocentrotus droebachiensis, and Strongylocentrotus purpuratus. Cell surface glycoproteins were characterized on the basis of lectin binding specificity with a novel lectin affinity transfer technique. Using this procedure, cell-type specific surface proteins, which are also lectin-binding specific, can be detected. In addition, fluorescein conjugated lectins were microinjected into the blastocoels of living S. drobachiensis and Lytechinus pictus embryos and the patterns of lectin bindings observed by fluorescence microscopy. The evidence presented in this thesis suggests that the differentiation of the primary mesenchyme cells is correlated with changes in the molecular composition of the cell-surface and the ECM

  6. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    representation of groundwater in the hydrological model is found to important and this imply resolving the small river valleys. Because, the important shallow groundwater is found in the river valleys. If the model does not represent the shallow groundwater then the area mean surface flux calculation......The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...... by the hydrological model is found to be insensitive to model resolution. Furthermore, this study highlights the effect of bias precipitation by regional climate model and it implications for hydrological modelling....

  7. Interaction of alcohols with the calcite surface

    DEFF Research Database (Denmark)

    Bovet, Nicolas Emile; Yang, Mingjun; Javadi, Meshkat Sadat

    2015-01-01

    . Controlling their growth requires complex polysaccharides. Polysaccharide activity depends on the functionality of OH groups, so to simplify the system in order to get closer to a molecular level understanding, we investigated the interaction of OH from a suite of alcohols with clean, freshly cleaved calcite...... surfaces. X-ray photoelectron spectroscopy (XPS) provided binding energies and revealed the extent of surface coverage. Molecular dynamics (MD) simulations supplemented with information about molecule ordering, orientation and packing density. The results show that all alcohols studied bond...... with the calcite surface through the OH group, with their carbon chains sticking away in a standing-up orientation. Alcohol molecules are closely packed and form a well-ordered monolayer on the surface....

  8. Interactions between semiconductor nanowires and living cells.

    Science.gov (United States)

    Prinz, Christelle N

    2015-06-17

    Semiconductor nanowires are increasingly used for biological applications and their small dimensions make them a promising tool for sensing and manipulating cells with minimal perturbation. In order to interface cells with nanowires in a controlled fashion, it is essential to understand the interactions between nanowires and living cells. The present paper reviews current progress in the understanding of these interactions, with knowledge gathered from studies where living cells were interfaced with vertical nanowire arrays. The effect of nanowires on cells is reported in terms of viability, cell-nanowire interface morphology, cell behavior, changes in gene expression as well as cellular stress markers. Unexplored issues and unanswered questions are discussed.

  9. Glioblastoma progression is assisted by induction of immunosuppressive function of pericytes through interaction with tumor cells

    Science.gov (United States)

    Valdor, Rut; García-Bernal, David; Bueno, Carlos; Ródenas, Mónica; Moraleda, José M.; Macian, Fernando; Martínez, Salvador

    2017-01-01

    The establishment of immune tolerance during Glioblastoma Multiforme (GBM) progression, is characterized by high levels expression of anti-inflammatory cytokines, which suppress the function of tumor assocciated myeloid cells, and the activation and expansion of tumor antigen specific T cells. However, the mechanisms underlying the failed anti-tumor immune response around the blood vessels during GBM, are poorly understood. The consequences of possible interactions between cancer cells and the perivascular compartment might affect the tumor growth. In this work we show for the first time that GBM cells induce immunomodulatory changes in pericytes in a cell interaction-dependent manner, acquiring an immunosuppresive function that possibly assists the evasion of the anti-tumor immune response and consequently participates in tumor growth promotion. Expression of high levels of anti-inflammatory cytokines was detected in vitro and in vivo in brain pericytes that interacted with GBM cells (GBC-PC). Furthermore, reduction of surface expression of co-stimulatory molecules and major histocompatibility complex molecules in GBC-PC correlated with a failure of antigen presentation to T cells and the acquisition of the ability to supress T cell responses. In vivo, orthotopic xenotransplant of human glioblastoma in an immunocompetent mouse model showed significant GBM cell proliferation and tumor growth after the establishment of interspecific immunotolerance that followed GMB interaction with pericytes. PMID:28978142

  10. Computer simulation of biomolecule–biomaterial interactions at surfaces and interfaces

    International Nuclear Information System (INIS)

    Wang, Qun; Wang, Meng-hao; Lu, Xiong; Wang, Ke-feng; Zhang, Xing-dong; Liu, Yaling; Zhang, Hong-ping

    2015-01-01

    Biomaterial surfaces and interfaces are intrinsically complicated systems because they involve biomolecules, implanted biomaterials, and complex biological environments. It is difficult to understand the interaction mechanism between biomaterials and biomolecules through conventional experimental methods. Computer simulation is an effective way to study the interaction mechanism at the atomic and molecular levels. In this review, we summarized the recent studies on the interaction behaviors of biomolecules with three types of the most widely used biomaterials: hydroxyapatite (HA), titanium oxide (TiO 2 ), and graphene(G)/graphene oxide(GO). The effects of crystal forms, crystallographic planes, surface defects, doping atoms, and water environments on biomolecules adsorption are discussed in detail. This review provides valuable theoretical guidance for biomaterial designing and surface modification. (topical review)

  11. Cell-substrate interaction with cell-membrane-stress dependent adhesion.

    Science.gov (United States)

    Jiang, H; Yang, B

    2012-01-10

    Cell-substrate interaction is examined in a two-dimensional mechanics model. The cell and substrate are treated as a shell and an elastic solid, respectively. Their interaction through adhesion is treated using nonlinear springs. Compared to previous cell mechanics models, the present model introduces a cohesive force law that is dependent not only on cell-substrate distance but also on internal cell-membrane stress. It is postulated that a living cell would establish focal adhesion sites with density dependent on the cell-membrane stress. The formulated mechanics problem is numerically solved using coupled finite elements and boundary elements for the cell and the substrate, respectively. The nodes in the adhesion zone from either side are linked by the cohesive springs. The specific cases of a cell adhering to a homogeneous substrate and a heterogeneous bimaterial substrate are examined. The analyses show that the substrate stiffness affects the adhesion behavior significantly and regulates the direction of cell adhesion, in good agreement with the experimental results in the literature. By introducing a reactive parameter (i.e., cell-membrane stress) linking biological responses of a living cell to a mechanical environment, the present model offers a unified mechanistic vehicle for characterization and prediction of living cell responses to various kinds of mechanical stimuli including local extracellular matrix and neighboring cells. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Interaction of β-sheet folds with a gold surface.

    Directory of Open Access Journals (Sweden)

    Martin Hoefling

    Full Text Available The adsorption of proteins on inorganic surfaces is of fundamental biological importance. Further, biomedical and nanotechnological applications increasingly use interfaces between inorganic material and polypeptides. Yet, the underlying adsorption mechanism of polypeptides on surfaces is not well understood and experimentally difficult to analyze. Therefore, we investigate here the interactions of polypeptides with a gold(111 surface using computational molecular dynamics (MD simulations with a polarizable gold model in explicit water. Our focus in this paper is the investigation of the interaction of polypeptides with β-sheet folds. First, we concentrate on a β-sheet forming model peptide. Second, we investigate the interactions of two domains with high β-sheet content of the biologically important extracellular matrix protein fibronectin (FN. We find that adsorption occurs in a stepwise mechanism both for the model peptide and the protein. The positively charged amino acid Arg facilitates the initial contact formation between protein and gold surface. Our results suggest that an effective gold-binding surface patch is overall uncharged, but contains Arg for contact initiation. The polypeptides do not unfold on the gold surface within the simulation time. However, for the two FN domains, the relative domain-domain orientation changes. The observation of a very fast and strong adsorption indicates that in a biological matrix, no bare gold surfaces will be present. Hence, the bioactivity of gold surfaces (like bare gold nanoparticles will critically depend on the history of particle administration and the proteins present during initial contact between gold and biological material. Further, gold particles may act as seeds for protein aggregation. Structural re-organization and protein aggregation are potentially of immunological importance.

  13. Investigations on the micro-scale surface interactions at the tool and workpiece interface in micro-manufacturing of bipolar plates for proton exchange membrane fuel cells

    Science.gov (United States)

    Peker, Mevlut Fatih

    Micro-forming studies have been more attractive in recent years because of miniaturization trend. One of the promising metal forming processes, micro-stamping, provides durability, strength, surface finish, and low cost for metal products. Hence, it is considered a prominent method for fabricating bipolar plates (BPP) with micro-channel arrays on large metallic surfaces to be used in Proton Exchange Membrane Fuel Cells (PEMFC). Major concerns in micro-stamping of high volume BPPs are surface interactions between micro-stamping dies and blank metal plates, and tribological changes. These concerns play a critical role in determining the surface quality, channel formation, and dimensional precision of bipolar plates. The surface quality of BPP is highly dependent on the micro-stamping die surface, and process conditions due to large ratios of surface area to volume (size effect) that cause an increased level of friction and wear issues at the contact interface. Due to the high volume and fast production rates, BPP surface characteristics such as surface roughness, hardness, and stiffness may change because of repeated interactions between tool (micro-forming die) and workpiece (sheet blank of interest). Since the surface characteristics of BPPs have a strong effect on corrosion and contact resistance of bipolar plates, and consequently overall fuel cell performance, evolution of surface characteristics at the tool and workpiece should be monitored, controlled, and kept in acceptable ranges throughout the long production cycles to maintain the surface quality. Compared to macro-forming operations, tribological changes in micro-forming process are bigger challenges due to their dominance and criticality. Therefore, tribological size effect should be considered for better understanding of tribological changes in micro-scale. The integrity of process simulation to the experiments, on the other hand, is essential. This study describes an approach that aims to investigate

  14. Electrostatic energy and screened charge interaction near the surface of metals with different Fermi surface shape

    Science.gov (United States)

    Gabovich, A. M.; Il'chenko, L. G.; Pashitskii, E. A.; Romanov, Yu. A.

    1980-04-01

    Using the Poisson equation Green function for a self-consistent field in a spatially inhomogeneous system, expressions for the electrostatic energy and screened charge interaction near the surface of a semi-infinite metal and a thin quantizing film are derived. It is shown that the decrease law and Friedel oscillation amplitude of adsorbed atom indirect interaction are determined by the electron spectrum character and the Fermi surface shape. The results obtained enable us to explain, in particular, the submonolayer adsorbed film structure on the W and Mo surfaces.

  15. Dendritic Cells in the Gut: Interaction with Intestinal Helminths

    Directory of Open Access Journals (Sweden)

    Fela Mendlovic

    2010-01-01

    Full Text Available The mucosal environment in mammals is highly tolerogenic; however, after exposure to pathogens or danger signals, it is able to shift towards an inflammatory response. Dendritic cells (DCs orchestrate immune responses and are highly responsible, through the secretion of cytokines and expression of surface markers, for the outcome of such immune response. In particular, the DC subsets found in the intestine have specialized functions and interact with different immune as well as nonimmune cells. Intestinal helminths primarily induce Th2 responses where DCs have an important yet not completely understood role. In addition, this cross-talk results in the induction of regulatory T cells (T regs as a result of the homeostatic mucosal environment. This review highlights the importance of studying the particular relation “helminth-DC-milieu” in view of the significance that each of these factors plays. Elucidating the mechanisms that trigger Th2 responses may provide the understanding of how we might modulate inflammatory processes.

  16. Interaction of lectins with membrane receptors on erythrocyte surfaces.

    Science.gov (United States)

    Sung, L A; Kabat, E A; Chien, S

    1985-08-01

    The interactions of human genotype AO erythrocytes (red blood cells) (RBCs) with N-acetylgalactosamine-reactive lectins isolated from Helix pomatia (HPA) and from Dolichos biflorus (DBA) were studied. Binding curves obtained with the use of tritium-labeled lectins showed that the maximal numbers of lectin molecules capable of binding to human genotype AO RBCs were 3.8 X 10(5) and 2.7 X 10(5) molecules/RBC for HPA and DBA, respectively. The binding of one type of lectin may influence the binding of another type. HPA was found to inhibit the binding of DBA, but not vice versa. The binding of HPA was weakly inhibited by a beta-D-galactose-reactive lectin isolated from Ricinus communis (designated RCA1). Limulus polyphemus lectin (LPA), with specificity for N-acetylneuraminic acid, did not influence the binding of HPA but enhanced the binding of DBA. About 80% of LPA receptors (N-acetylneuraminic acid) were removed from RBC surfaces by neuraminidase treatment. Neuraminidase treatment of RBCs resulted in increases of binding of both HPA and DBA, but through different mechanisms. An equal number (7.6 X 10(5) of new HPA sites were generated on genotypes AO and OO RBCs by neuraminidase treatment, and these new sites accounted for the enhancement (AO cells) and appearance (OO cells) of hemagglutinability by HPA. Neuraminidase treatment did not generate new DBA sites, but increased the DBA affinity for the existing receptors; as a result, genotype AO cells increased their hemagglutinability by DBA, while OO cells remained unagglutinable. The use of RBCs of different genotypes in binding assays with 3H-labeled lectins of known specificities provides an experimental system for studying cell-cell recognition and association.

  17. 52nd colloid and surface science symposium. Proceedings volume

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, E.L. Jr.; Corbett, H.G.

    1978-05-01

    Abstracts are presented under the headings: cell/surface interactions, surface properties and reactions of catalysts, solution chemistry of surfactants, dynamic systems, microorganism/surface interactions, gas-solid interactions, biological surfaces, solid sorbents, lung surfactant and intestinal absorption, pigments, and liquid systems. (DLC)

  18. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES

    Science.gov (United States)

    Non-bonded interactions between model pesticides and organo-mineral surfaces have been studied using molecular mechanical conformational calculations and molecular dynamics simulations. The minimum energy conformations and relative binding energies for the interaction of atrazine...

  19. Modelling of energetic molecule-surface interactions

    International Nuclear Information System (INIS)

    Kerford, M.

    2000-09-01

    This thesis contains the results of molecular dynamics simulations of molecule-surface interactions, looking particularly at fullerene molecules and carbon surfaces. Energetic impacts of fullerene molecules on graphite create defect craters. The relationship between the parameters of the impacting molecule and the parameters of the crater axe examined and found to be a function of the energy and velocity of the impacting molecule. Less energetic fullerene molecules can be scattered from a graphite surface and the partitioning of energy after a scattering event is investigated. It is found that a large fraction of the kinetic energy retained after impact is translational energy, with a small fraction of rotational energy and a number of vibrational modes. At impact energies where the surface is not broken and at normal incidence, surface waves axe seen to occur. These waves axe used to develop a method of desorbing molecules from a graphite surface without damage to either the surface or the molecules being desorbed. A number of fullerene molecules are investigated and ways to increase the desorption yield are examined. It is found that this is a successful technique for desorbing large numbers of intact molecules from graphite. This technique could be used for desorbing intact molecules into a gas phase for mass spectrometric analysis. (author)

  20. Biomaterials surface science

    CERN Document Server

    Taubert, Andreas; Rodriguez-Cabello, José Carlos

    2013-01-01

    The book provides an overview of the highly interdisciplinary field of surface science in the context of biological and biomedical applications. The covered topics range from micro- and nanostructuring for imparting functionality in a top-down manner to the bottom-up fabrication of gradient surfaces by self-assembly, from interfaces between biomaterials and living matter to smart, stimuli-responsive surfaces, and from cell and surface mechanics to the elucidation of cell-chip interactions in biomedical devices.

  1. Spectral asymptotics of a strong δ′ interaction supported by a surface

    International Nuclear Information System (INIS)

    Exner, Pavel; Jex, Michal

    2014-01-01

    Highlights: • Attractive δ ′ interactions supported by a smooth surface are considered. • Surfaces can be either infinite and asymptotically planar, or compact and closed. • Spectral asymptotics is determined by the geometry of the interaction support. - Abstract: We derive asymptotic expansion for the spectrum of Hamiltonians with a strong attractive δ ′ interaction supported by a smooth surface in R 3 , either infinite and asymptotically planar, or compact and closed. Its second term is found to be determined by a Schrödinger type operator with an effective potential expressed in terms of the interaction support curvatures

  2. Interaction of the effects of hyperthermia and ionizing radiation on cell survival

    International Nuclear Information System (INIS)

    Loshek, D.D.

    1976-09-01

    The literature concerning the effects of hyperthermia and radiation on cellular reproductive integrity is reviewed. The cell line and the physical and biological aspects of the experiments are described. Preliminary experiments revealed that the experimental stability was adequate for inter-experiment comparisons, provided that sufficient control data were obtained. Further experiments provided a cursory examination of several aspects of the interaction between radiation and hyperthermia. A simple sensitization model that would account for the observed results for any single value of the perturbing radiation or hyperthermia dose was developed. Using the concept of the survival surface, this simple model was expanded to describe simultaneously survivals for any combination of the radiation and hyperthermia dose. The interaction component of this model is first order in both hyperthermia exposure and radiation dose. The mechanism by which radiation contributes to the interaction was investigated by altering the radiation quality. The results suggest that high LET events contribute to the interaction. The mechanism by which hyperthermia contributes to the interaction was investigated by altering the hyperthermia temperature. A thermodynamic analysis of the data reveals parallels with the effects of hyperthermia and radiation on protein, suggesting a possible involvement of protein denaturation in cell inactivation. (author)

  3. Element-specific density profiles in interacting biomembrane models

    International Nuclear Information System (INIS)

    Schneck, Emanuel; Rodriguez-Loureiro, Ignacio; Bertinetti, Luca; Gochev, Georgi; Marin, Egor; Novikov, Dmitri; Konovalov, Oleg

    2017-01-01

    Surface interactions involving biomembranes, such as cell–cell interactions or membrane contacts inside cells play important roles in numerous biological processes. Structural insight into the interacting surfaces is a prerequisite to understand the interaction characteristics as well as the underlying physical mechanisms. Here, we work with simplified planar experimental models of membrane surfaces, composed of lipids and lipopolymers. Their interaction is quantified in terms of pressure–distance curves using ellipsometry at controlled dehydrating (interaction) pressures. For selected pressures, their internal structure is investigated by standing-wave x-ray fluorescence (SWXF). This technique yields specific density profiles of the chemical elements P and S belonging to lipid headgroups and polymer chains, as well as counter-ion profiles for charged surfaces. (paper)

  4. Interaction of Proteins Identified in Human Thyroid Cells

    Science.gov (United States)

    Pietsch, Jessica; Riwaldt, Stefan; Bauer, Johann; Sickmann, Albert; Weber, Gerhard; Grosse, Jirka; Infanger, Manfred; Eilles, Christoph; Grimm, Daniela

    2013-01-01

    Influence of gravity forces on the regulation of protein expression by healthy and malignant thyroid cells was studied with the aim to identify protein interactions. Western blot analyses of a limited number of proteins suggested a time-dependent regulation of protein expression by simulated microgravity. After applying free flow isoelectric focusing and mass spectrometry to search for differently expressed proteins by thyroid cells exposed to simulated microgravity for three days, a considerable number of candidates for gravi-sensitive proteins were detected. In order to show how proteins sensitive to microgravity could directly influence other proteins, we investigated all polypeptide chains identified with Mascot scores above 100, looking for groups of interacting proteins. Hence, UniProtKB entry numbers of all detected proteins were entered into the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and processed. The program indicated that we had detected various groups of interacting proteins in each of the three cell lines studied. The major groups of interacting proteins play a role in pathways of carbohydrate and protein metabolism, regulation of cell growth and cell membrane structuring. Analyzing these groups, networks of interaction could be established which show how a punctual influence of simulated microgravity may propagate via various members of interaction chains. PMID:23303277

  5. Interaction of Proteins Identified in Human Thyroid Cells

    Directory of Open Access Journals (Sweden)

    Jessica Pietsch

    2013-01-01

    Full Text Available Influence of gravity forces on the regulation of protein expression by healthy and malignant thyroid cells was studied with the aim to identify protein interactions. Western blot analyses of a limited number of proteins suggested a time-dependent regulation of protein expression by simulated microgravity. After applying free flow isoelectric focusing and mass spectrometry to search for differently expressed proteins by thyroid cells exposed to simulated microgravity for three days, a considerable number of candidates for gravi-sensitive proteins were detected. In order to show how proteins sensitive to microgravity could directly influence other proteins, we investigated all polypeptide chains identified with Mascot scores above 100, looking for groups of interacting proteins. Hence, UniProtKB entry numbers of all detected proteins were entered into the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING and processed. The program indicated that we had detected various groups of interacting proteins in each of the three cell lines studied. The major groups of interacting proteins play a role in pathways of carbohydrate and protein metabolism, regulation of cell growth and cell membrane structuring. Analyzing these groups, networks of interaction could be established which show how a punctual influence of simulated microgravity may propagate via various members of interaction chains.

  6. Electric double layer interactions in bacterial adhesion to surfaces

    NARCIS (Netherlands)

    Poortinga, AT; Norde, W; Busscher, HJ; Bos, R.R.M.

    2002-01-01

    The DLVO (Derjaguin, Landau, Verwey, Overbeek) theory was originally developed to describe interactions between non-biological lyophobic colloids such as polystyrene particles, but is also used to describe bacterial adhesion to surfaces. Despite the differences between the surface of bacteria and

  7. CD28-CD80 interactions control regulatory T cell motility and immunological synapse formation1,2

    Science.gov (United States)

    Thauland, Timothy J.; Koguchi, Yoshinobu; Dustin, Michael L.; Parker, David C.

    2014-01-01

    Regulatory T cells (Tregs) are essential for tolerance to self and environmental antigens, acting in part by downmodulating costimulatory molecules on the surface of dendritic cells (DCs) and altering naïve CD4 T cell-DC interactions. Here, we show that Tregs form stable conjugates with DCs before, but not after, they decrease surface expression of the costimulatory molecule CD80 on the DCs. We use supported planar bilayers to show that Tregs dramatically slow down, but maintain a highly polarized and motile phenotype after recognizing antigen in the absence of costimulation. These motile cells are characterized by distinct accumulations of LFA-1-ICAM-1 in the lamella and TCR-MHC in the uropod, consistent with a motile immunological synapse or ‘kinapse’. However, in the presence of high, but not low, concentrations of CD80, Tregs form stationary, symmetrical synapses. Using blocking antibodies, we show that, while CTLA-4 is required for CD80 downmodulation, CD28-CD80 interactions are critical for modulating Treg motility in the presence of antigen. Together, these results support the hypothesis that Tregs are tuned to alter their motility depending on costimulatory signals. PMID:25355918

  8. Effect of surface organic coatings of cellulose nanocrystals on the viability of mammalian cell lines

    Directory of Open Access Journals (Sweden)

    Jimenez AS

    2017-09-01

    Full Text Available Ambar S Jimenez,1 Francesca Jaramillo,1 Usha D Hemraz,2 Yaman Boluk,3 Karina Ckless,1 Rajesh Sunasee1 1Department of Chemistry, State University of New York at Plattsburgh, Plattsburgh, NY, USA; 2National Research Council, Montreal, QC, Canada, 3Department of Civil & Environmental Engineering, University of Alberta and National Institute for Nanotechnology, National Research Council, Edmonton, AB, Canada Abstract: Cellulose nanocrystals (CNCs have emerged as promising candidates for a number of bio-applications. Surface modification of CNCs continues to gain significant research interest as it imparts new properties to the surface of the nanocrystals for the design of multifunctional CNCs-based materials. A small chemical surface modification can potentially lead to drastic behavioral changes of cell-material interactions thereby affecting the intended bio-application. In this work, unmodified CNCs were covalently decorated with four different organic moieties such as a diaminobutane fragment, a cyclic oligosaccharide (β-cyclodextrin, a thermoresponsive polymer (poly[N-isopropylacrylamide], and a cationic aminomethacrylamide-based polymer using different synthetic covalent methods. The effect of surface coatings of CNCs and the respective dose-response of the above organic moieties on the cell viability were evaluated on mammalian cell cultures (J774A.1 and MFC-7, using 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays. Overall, the results indicated that cells exposed to surface-coated CNCs for 24 h did not display major changes in cell viability, membrane permeability as well as cell morphology. However, with longer exposure, all these parameters were somewhat affected, which appears not to be correlated with either anionic or cationic surface coatings of CNCs used in this study. Keywords: cellulose nanocrystals, surface coating, cell viability, MTT, LDH

  9. Interaction of ethanol and water with the {1014} surface of calcite

    DEFF Research Database (Denmark)

    Cooke, David; Gray, R J; Sand, K K

    2010-01-01

    Molecular dynamics simulations have been used to model the interaction between ethanol, water, and the {1014} surface of calcite. Our results demonstrate that a single ethanol molecule is able to form two interactions with the mineral surface (both Ca-O and O-H), resulting in a highly ordered, st...

  10. The Character of the Solar Wind, Surface Interactions, and Water

    Science.gov (United States)

    Farrell, William M.

    2011-01-01

    We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

  11. Comparative of fibroblast and osteoblast cells adhesion on surface modified nanofibrous substrates based on polycaprolactone

    OpenAIRE

    Sharifi, Fereshteh; Irani, Shiva; Zandi, Mojgan; Soleimani, Masoud; Atyabi, Seyed Mohammad

    2016-01-01

    One of the determinant factors for successful bioengineering is to achieve appropriate nano-topography and three-dimensional substrate. In this research, polycaprolactone (PCL) nano-fibrous mat with different roughness modified with O2 plasma was fabricated via electrospinning. The purpose of this study was to evaluate the effect of plasma modification along with surface nano-topography of mats on the quality of human fibroblast (HDFs) and osteoblast cells (OSTs)-substrate interaction. Surfac...

  12. Interaction of the Helium, Hydrogen, Air, Argon, and Nitrogen Bubbles with Graphite Surface in Water.

    Science.gov (United States)

    Bartali, Ruben; Otyepka, Michal; Pykal, Martin; Lazar, Petr; Micheli, Victor; Gottardi, Gloria; Laidani, Nadhira

    2017-05-24

    The interaction of the confined gas with solid surface immersed in water is a common theme of many important fields such as self-cleaning surface, gas storage, and sensing. For that reason, we investigated the gas-graphite interaction in the water medium. The graphite surface was prepared by mechanical exfoliation of highly oriented pyrolytic graphite (HOPG). The surface chemistry and morphology were studied by X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy. The surface energy of HOPG was estimated by contact angle measurements using the Owens-Wendt method. The interaction of gases (Ar, He, H 2 , N 2 , and air) with graphite was studied by a captive bubble method, in which the gas bubble was in contact with the exfoliated graphite surface in water media. The experimental data were corroborated by molecular dynamics simulations and density functional theory calculations. The surface energy of HOPG equaled to 52.8 mJ/m 2 and more of 95% of the surface energy was attributed to dispersion interactions. The results on gas-surface interaction indicated that HOPG surface had gasphilic behavior for helium and hydrogen, while gasphobic behavior for argon and nitrogen. The results showed that the variation of the gas contact angle was related to the balance between the gas-surface and gas-gas interaction potentials. For helium and hydrogen the gas-surface interaction was particularly high compared to gas-gas interaction and this promoted the favorable interaction with graphite surface.

  13. A Simple Hydrophilic Treatment of SU-8 Surfaces for Cell Culturing and Cell Patterning

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Stangegaard, Michael; Dufva, Hans Martin

    2005-01-01

    SU-8, an epoxy-based photoresist, widely used in constitution different mTAS systems, is incompatible with mammalian cell adhesion and culture in its native form. Here, we demonstrate a simple, cheap and robust two-step method to render a SU-8 surface hydrophilic and compatible with cell culture........ The contact angle of SU-8 surface was significantly reduced from 90° to 25° after the surface modification. The treated SU-8 surfaces provided a cell culture environment that was comparable with cell culture flask surface in terms of generation time and morphology....

  14. Self-energies and the interactions of particles with surfaces

    International Nuclear Information System (INIS)

    Manson, J.R.; Ritchie, R.H.; Echenique, P.M.; Gras-Marti, A.

    1987-01-01

    We have in this paper reviewed the method of treating many-body problems by means of an effective interaction self-energy. We have developed an alternatvie approach to the self-energy which is simpler and more straight-forward than standard methods, and we have illustrated its use with two examples of a charge interacting with a metal surface. In each case the self-energy produces the classical image potential together with corrections due to quantum mechanical effects. This method has also been successfully applied to the problem of an atom interacting with a surface. Corrections to the Van der Waals dispersion force are obtained, and via the non-conservative imaginary parts to /summation//sub i/(z) we discuss transition rates and energy exchange. 14 refs., 1 fig

  15. Interaction of phosphorylcholine with fibronectin coatings: Surface characterization and biological performances

    Energy Technology Data Exchange (ETDEWEB)

    Montaño-Machado, Vanessa, E-mail: vanessa.montano-machado.1@ulaval.ca [Laboratory for Biomaterials and Bioengineering, Dept. of Min-Met-Materials Eng., & University Hospital Research Center, Laval University, University Campus, PLT-1745G, Québec, Québec, G1 V 0A6 (Canada); ERRMECe, University of Cergy-Pontoise, Site Saint-Martin, 2 Avenue Adolphe Chauvin, 95302 Cergy-Pontoise Cedex (France); Noël, Céline, E-mail: celine.noel@unamur.be [Research Centre in Physics of Matter and Radiation (PMR), Université de Namur, 61 rue de Bruxelles, B-5000 Namur (Belgium); Chevallier, Pascale, E-mail: pascale.chevallier@crchudequebec.ulaval.ca [Laboratory for Biomaterials and Bioengineering, Dept. of Min-Met-Materials Eng., & University Hospital Research Center, Laval University, University Campus, PLT-1745G, Québec, Québec, G1 V 0A6 (Canada); Turgeon, Stéphane, E-mail: stephane.turgeon@crchudequebec.ulaval.ca [Laboratory for Biomaterials and Bioengineering, Dept. of Min-Met-Materials Eng., & University Hospital Research Center, Laval University, University Campus, PLT-1745G, Québec, Québec, G1 V 0A6 (Canada); Houssiau, Laurent, E-mail: laurent.houssiau@unamur.be [Research Centre in Physics of Matter and Radiation (PMR), Université de Namur, 61 rue de Bruxelles, B-5000 Namur (Belgium); Pauthe, Emmanuel, E-mail: emmanuel.pauthe@u-cergy.fr [ERRMECe, University of Cergy-Pontoise, Site Saint-Martin, 2 Avenue Adolphe Chauvin, 95302 Cergy-Pontoise Cedex (France); and others

    2017-02-28

    Highlights: • Fibronectin/phosphorylcholine coatings on plasma deposited fluorocarbon films were created. • The effect of several coating techniques on the surface biological performances was evaluated. • XPS, DWCA, immunostaining and ToF-SIMS (imaging and depth profiling) techniques were applied. • Potential for cardiovascular applications was showed by endothelial cell and blood interactions. - Abstract: Coating medical devices with several bioactive molecules is an interesting approach to achieve specific biological targets upon the interaction of the biomaterial with the living environment. In this work, a fluorocarbon polymer (CF{sub x}) was first deposited by plasma treatment on stainless steel (SS) substrate and thereafter, coatings containing fibronectin (FN) and phosphorylcholine (PRC) were created for cardiovascular applications. These two biomolecules were chosen to promote endothelialization and to avoid thrombus formation, respectively. Adsorption and grafting techniques were applied – and combined – to accomplish 4 different coatings containing both molecules. However, big challenge was found to characterize a small molecule (PRC: 184 g/mol) interacting with a protein (FN: 450 kD). For the first time XPS, dynamic water contact angle, immunostaining and ToF-SIMS (imaging and depth profiling) analyses were combined to accomplish the characterization of such a coating. The most encouraging biological performances were obtained for samples where FN was grafted to the CF{sub x} film followed by the adsorption of PRC: proliferation of endothelial cells and hemocompatibility properties were observed. Promising coatings for cardiovascular applications were developed. The relevance of characterizing the coatings with high sensitive techniques and the further correlation with their biological performances were evidenced.

  16. Development and Application of a Flow Reactor Cell for Studies of Surface Chemistry

    Science.gov (United States)

    Algrim, L. B.; Pagonis, D.; Price, D.; Day, D. A.; De Gouw, J. A.; Jimenez, J. L.; Ziemann, P. J.

    2017-12-01

    We have designed, constructed, characterized, and employed a flow reactor cell that can be used to investigate the interaction of gaseous species such as volatile organic compounds (VOCs), oxidants, acids, and water vapor with authentic and model surfaces that are present in indoor and outdoor environments. The 3.9 L rectangular cell is made of FEP-coated aluminum and has one open face that can be sealed to the surface of interest. An internal plunger is raised (lowered) to expose (cover) the surface while various probe chemicals are added to the flow. To date we have exposed painted surfaces to O3, OH radicals (made from reaction of O3 with tetramethylethene and from photolysis of methyl nitrate/NO mixtures), and NO3 radicals (made from thermal decomposition N2O5) and analyzed the emitted oxidation products with a proton transfer reaction mass spectrometer (PTR-MS) and chemical ionization mass spectrometer (CIMS) equipped with an iodide reagent ion source. Further studies have included the reaction of oxidants with surfaces coated with organic films such as squalene and polyethylene glycol, as well as uptake of ketones and acids from the gas-phase to painted surfaces. The cell was also recently deployed at the University of Colorado-Boulder Art Museum during spring of 2017 to investigate the oxidation products released from the museum walls and floors. Results from all of these studies will be presented.

  17. Mapping the Complex Morphology of Cell Interactions with Nanowire Substrates Using FIB-SEM

    DEFF Research Database (Denmark)

    Wierzbicki, Rafal; Købler, Carsten; Jensen, Mikkel Ravn Boye

    2013-01-01

    Using high resolution focused ion beam scanning electron microscopy (FIB-SEM) we study the details of cell-nanostructure interactions using serial block face imaging. 3T3 Fibroblast cellular monolayers are cultured on flat glass as a control surface and on two types of nanostructured scaffold...... substrates made from silicon black (Nanograss) with low- and high nanowire density. After culturing for 72 hours the cells were fixed, heavy metal stained, embedded in resin, and processed with FIB-SEM block face imaging without removing the substrate. The sample preparation procedure, image acquisition...

  18. Effects of diffusion and surface interactions on the line shape of electron paramagnetic resonances in the presence of a magnetic field gradient

    International Nuclear Information System (INIS)

    Schaden, M.; Zhao, K. F.; Wu, Z.

    2007-01-01

    In an evanescent wave magnetometer the Zeeman polarization is probed at micrometer to submicrometer distances from the cell surface. The electron paramagnetic resonance lines of an evanescent wave magnetometer in the presence of a magnetic field gradient exhibit edge enhancement seen previously in nuclear magnetic resonance lines. We present a theoretical model that describes quantitatively the shape of the magnetic resonance lines of an evanescent wave magnetometer under a wide range of experimental conditions. It accounts for diffusion broadening in the presence of a magnetic field gradient as well as interactions of spin polarized Rb atoms with the coated Pyrex glass surfaces. Depending on the field gradient, cell thickness, and buffer gas pressure, the resonance line may have the form of a single asymmetric peak or two peaks localized near the front and back surfaces in frequency space. The double-peaked response depends on average characteristics of the surface interactions. Its shape is sensitive to the dwell time, relaxation probability, and average phase shift of adsorbed spin polarized Rb atoms

  19. Electron microscopy study of antioxidant interaction with bacterial cells

    Science.gov (United States)

    Plotnikov, Oleg P.; Novikova, Olga V.; Konnov, Nikolai P.; Korsukov, Vladimir N.; Gunkin, Ivan F.; Volkov, Uryi P.

    2000-10-01

    To maintain native microorganisms genotype and phenotype features a lyophylization technique is widely used. However in this case cells are affected by influences of vacuum and low temperature that cause a part of the cells population to be destruction. Another factor reduced microorganisms vitality is formation of reactive oxygen forms that damage certain biological targets (such as DNA, membranes etc.) Recently to raise microorganism's resistance against adverse condition natural and synthetic antioxidants are used. Antioxidant- are antagonists of free radicals. Introduction of antioxidants in protective medium for lyophylization increase bacteria storage life about 2,0-4,8 fold in comparison with reference samples. In the article the main results of our investigation of antioxidants interaction with microorganism cells is described. As bacteria cells we use vaccine strain yersinia pestis EV, that were grown for 48 h at 28 degree(s)C on the Hottinger agar (pH 7,2). Antioxidants are inserted on the agar surface in specimen under test. To investigate a localization of antioxidants for electron microscopy investigation, thallium organic antioxidants were used. The thallium organic compounds have an antioxidant features if thallium is in low concentration (about 1(mu) g/ml). The localization of the thallium organic antioxidants on bacteria Y. pestis EV is visible in electron microscopy images, thallium being heavy metal with high electron density. The negatively stained bacteria and bacteria thin sections with thallium organic compounds were investigated by means of transmission electron microscopy. The localization of the thallium organic compounds is clearly visible in electron micrographs as small dark spots with size about 10-80nm. Probably mechanisms of interaction of antioxidants with bacteria cells are discussed.

  20. CH-π Interaction Driven Macroscopic Property Transition on Smart Polymer Surface

    Science.gov (United States)

    Li, Minmin; Qing, Guangyan; Xiong, Yuting; Lai, Yuekun; Sun, Taolei

    2015-10-01

    Life systems have evolved to utilize weak noncovalent interactions, particularly CH-π interaction, to achieve various biofunctions, for example cellular communication, immune response, and protein folding. However, for artificial materials, it remains a great challenge to recognize such weak interaction, further transform it into tunable macroscopic properties and realize special functions. Here we integrate monosaccharide-based CH-π receptor capable of recognizing aromatic peptides into a smart polymer with three-component “Recognition-Mediating-Function” design, and report the CH-π interaction driven surface property switching on smart polymer film, including wettability, adhesion, viscoelasticity and stiffness. Detailed studies indicate that, the CH-π interaction induces the complexation between saccharide unit and aromatic peptide, which breaks the initial amphiphilic balance of the polymer network, resulting in contraction-swelling conformational transition for polymer chains and subsequent dramatic switching in surface properties. This work not only presents a new approach to control the surface property of materials, but also points to a broader research prospect on CH-π interaction at a macroscopic level.

  1. New Monoclonal Antibodies to Defined Cell Surface Proteins on Human Pluripotent Stem Cells.

    Science.gov (United States)

    O'Brien, Carmel M; Chy, Hun S; Zhou, Qi; Blumenfeld, Shiri; Lambshead, Jack W; Liu, Xiaodong; Kie, Joshua; Capaldo, Bianca D; Chung, Tung-Liang; Adams, Timothy E; Phan, Tram; Bentley, John D; McKinstry, William J; Oliva, Karen; McMurrick, Paul J; Wang, Yu-Chieh; Rossello, Fernando J; Lindeman, Geoffrey J; Chen, Di; Jarde, Thierry; Clark, Amander T; Abud, Helen E; Visvader, Jane E; Nefzger, Christian M; Polo, Jose M; Loring, Jeanne F; Laslett, Andrew L

    2017-03-01

    The study and application of human pluripotent stem cells (hPSCs) will be enhanced by the availability of well-characterized monoclonal antibodies (mAbs) detecting cell-surface epitopes. Here, we report generation of seven new mAbs that detect cell surface proteins present on live and fixed human ES cells (hESCs) and human iPS cells (hiPSCs), confirming our previous prediction that these proteins were present on the cell surface of hPSCs. The mAbs all show a high correlation with POU5F1 (OCT4) expression and other hPSC surface markers (TRA-160 and SSEA-4) in hPSC cultures and detect rare OCT4 positive cells in differentiated cell cultures. These mAbs are immunoreactive to cell surface protein epitopes on both primed and naive state hPSCs, providing useful research tools to investigate the cellular mechanisms underlying human pluripotency and states of cellular reprogramming. In addition, we report that subsets of the seven new mAbs are also immunoreactive to human bone marrow-derived mesenchymal stem cells (MSCs), normal human breast subsets and both normal and tumorigenic colorectal cell populations. The mAbs reported here should accelerate the investigation of the nature of pluripotency, and enable development of robust cell separation and tracing technologies to enrich or deplete for hPSCs and other human stem and somatic cell types. Stem Cells 2017;35:626-640. © 2016 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

  2. Taking advantage of reduced droplet-surface interaction to optimize transport of bioanalytes in digital microfluidics.

    Science.gov (United States)

    Freire, Sergio L S; Thorne, Nathaniel; Wutkowski, Michael; Dao, Selina

    2014-11-10

    Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of "lab-on-a-chip" platforms. Often, droplet motion relies on the wetting of a surface, directly associated with the application of an electric field; surface interactions, however, make motion dependent on droplet contents, limiting the breadth of applications of the technique. Some alternatives have been presented to minimize this dependence. However, they rely on the addition of extra chemical species to the droplet or its surroundings, which could potentially interact with droplet moieties. Addressing this challenge, our group recently developed Field-DW devices to allow the transport of cells and proteins in DMF, without extra additives. Here, the protocol for device fabrication and operation is provided, including the electronic interface for motion control. We also continue the studies with the devices, showing that multicellular, relatively large, model organisms can also be transported, arguably unaffected by the electric fields required for device operation.

  3. A cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing.

    Science.gov (United States)

    Ke, Guoliang; Zhu, Zhi; Wang, Wei; Zou, Yuan; Guan, Zhichao; Jia, Shasha; Zhang, Huimin; Wu, Xuemeng; Yang, Chaoyong James

    2014-09-10

    Accurate sensing of the extracellular pH is a very important yet challenging task in biological and clinical applications. This paper describes the development of an amphiphilic lipid-DNA molecule as a simple yet useful cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing. The lipid-DNA probe, which consists of a hydrophobic diacyllipid tail and a hydrophilic DNA strand, is modified with two fluorescent dyes; one is pH-sensitive as pH indicator and the other is pH-insensitive as an internal reference. The lipid-DNA probe showed sensitive and reversible response to pH change in the range of 6.0-8.0, which is suitable for most extracellular studies. In addition, based on simple hydrophobic interactions with the cell membrane, the lipid-DNA probe can be easily anchored on the cell surface with negligible cytotoxicity, excellent stability, and unique ratiometric readout, thus ensuring its accurate sensing of extracellular pH. Finally, this lipid-DNA-based ratiometric pH indicator was successfully used for extracellular pH sensing of cells in 3D culture environment, demonstrating the potential applications of the sensor in biological and medical studies.

  4. Enhancing Efficiency of Perovskite Solar Cells via Surface Passivation with Graphene Oxide Interlayer.

    Science.gov (United States)

    Li, Hao; Tao, Leiming; Huang, Feihong; Sun, Qiang; Zhao, Xiaojuan; Han, Junbo; Shen, Yan; Wang, Mingkui

    2017-11-08

    Perovskite solar cells have been demonstrated as promising low-cost and highly efficient next-generation solar cells. Enhancing V OC by minimization the interfacial recombination kinetics can further improve device performance. In this work, we for the first time reported on surface passivation of perovskite layers with chemical modified graphene oxides, which act as efficient interlayer to reduce interfacial recombination and enhance hole extraction as well. Our modeling points out that the passivation effect mainly comes from the interaction between functional group (4-fluorophenyl) and under-coordinated Pb ions. The resulting perovskite solar cells achieved high efficient power conversion efficiency of 18.75% with enhanced high open circuit V OC of 1.11 V. Ultrafast spectroscopy, photovoltage/photocurrent transient decay, and electronic impedance spectroscopy characterizations reveal the effective passivation effect and the energy loss mechanism. This work sheds light on the importance of interfacial engineering on the surface of perovskite layers and provides possible ways to improve device efficiency.

  5. The role of surface charge on the uptake and biocompatibility of hydroxyapatite nanoparticles with osteoblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen Liang; Mccrate, Joseph M; Li Hao [Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211 (United States); Lee, James C-M, E-mail: liha@missouri.edu [Department of Biological Engineering, University of Missouri, Columbia, MO 65211 (United States)

    2011-03-11

    The objective of this study is to evaluate the effect of hydroxyapatite (HAP) nanoparticles with different surface charges on the cellular uptake behavior and in vitro cell viability and proliferation of MC3T3-E1 cell lines (osteoblast). The nanoparticles' surface charge was varied by surface modification with two carboxylic acids: 12-aminododecanoic acid (positive) and dodecanedioic acid (negative). The untreated HAP nanoparticles and dodecanoic acid modified HAP nanoparticles (neutral) were used as the control. X-ray diffraction (XRD) revealed that surface modifications by the three carboxylic acids did not change the crystal structure of HAP nanoparticles; Fourier transform infrared spectroscopy (FT-IR) confirmed the adsorption and binding of the carboxylic acids on the HAP nanoparticles' surfaces; and zeta potential measurement confirmed that the chemicals successfully modified the surface charge of HAP nanoparticles in water based solution. Transmission electron microscopy (TEM) images showed that positively charged, negatively charged and untreated HAP nanoparticles, with similar size and shape, all penetrated into the cells and cells had more uptake of HAP nanoparticles with positive charge compared to those with negative charge, which might be attributed to the attractive or repulsive interaction between the negatively charged cell membrane and positively/negatively charged HAP nanoparticles. The neutral HAP nanoparticles could not penetrate the cell membrane due to their larger size. MTT assay and LDH assay results indicated that as compared with the polystyrene control, greater cell viability and cell proliferation were measured on MC3T3-E1 cells treated with the three kinds of HAP nanoparticles (neutral, positive, and untreated), among which positively charged HAP nanoparticles showed the strongest improvement for cell viability and cell proliferation. In summary, the surface charge of HAP nanoparticles can be modified to influence the cellular

  6. The role of surface charge on the uptake and biocompatibility of hydroxyapatite nanoparticles with osteoblast cells

    International Nuclear Information System (INIS)

    Chen Liang; Mccrate, Joseph M; Li Hao; Lee, James C-M

    2011-01-01

    The objective of this study is to evaluate the effect of hydroxyapatite (HAP) nanoparticles with different surface charges on the cellular uptake behavior and in vitro cell viability and proliferation of MC3T3-E1 cell lines (osteoblast). The nanoparticles' surface charge was varied by surface modification with two carboxylic acids: 12-aminododecanoic acid (positive) and dodecanedioic acid (negative). The untreated HAP nanoparticles and dodecanoic acid modified HAP nanoparticles (neutral) were used as the control. X-ray diffraction (XRD) revealed that surface modifications by the three carboxylic acids did not change the crystal structure of HAP nanoparticles; Fourier transform infrared spectroscopy (FT-IR) confirmed the adsorption and binding of the carboxylic acids on the HAP nanoparticles' surfaces; and zeta potential measurement confirmed that the chemicals successfully modified the surface charge of HAP nanoparticles in water based solution. Transmission electron microscopy (TEM) images showed that positively charged, negatively charged and untreated HAP nanoparticles, with similar size and shape, all penetrated into the cells and cells had more uptake of HAP nanoparticles with positive charge compared to those with negative charge, which might be attributed to the attractive or repulsive interaction between the negatively charged cell membrane and positively/negatively charged HAP nanoparticles. The neutral HAP nanoparticles could not penetrate the cell membrane due to their larger size. MTT assay and LDH assay results indicated that as compared with the polystyrene control, greater cell viability and cell proliferation were measured on MC3T3-E1 cells treated with the three kinds of HAP nanoparticles (neutral, positive, and untreated), among which positively charged HAP nanoparticles showed the strongest improvement for cell viability and cell proliferation. In summary, the surface charge of HAP nanoparticles can be modified to influence the cellular uptake of

  7. Fibroblast receptor for cell-substratum adhesion: studies on the interaction of baby hamster kidney cells with latex beads coated by cold insoluble globulin (plasma fibronectin)

    OpenAIRE

    1980-01-01

    Studies were carried out on the interactions of uncharged latex beads (0.76 micrometer) with baby hamster kidney cells. Binding of beads to the cells occurred if the beads were coated by cold insoluble globulin (CIG) (plasma fibronectin) but not if the beads were coated by bovine albumin. Bovine albumin-coated beads did not bind to the cells even in the presence of excess CIG in the incubation medium. Binding of beads occurred randomly over the entire surfaces of cells in suspension. However,...

  8. Strong coupling electrostatics for randomly charged surfaces: antifragility and effective interactions.

    Science.gov (United States)

    Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf

    2015-05-07

    We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to

  9. Green tea polyphenol tailors cell adhesivity of RGD displaying surfaces: multicomponent models monitored optically.

    Science.gov (United States)

    Peter, Beatrix; Farkas, Eniko; Forgacs, Eniko; Saftics, Andras; Kovacs, Boglarka; Kurunczi, Sandor; Szekacs, Inna; Csampai, Antal; Bosze, Szilvia; Horvath, Robert

    2017-02-10

    The interaction of the anti-adhesive coating, poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its Arg-Gly-Asp (RGD) functionalized form, PLL-g-PEG-RGD, with the green tea polyphenol, epigallocatechin-gallate (EGCg) was in situ monitored. After, the kinetics of cellular adhesion on the EGCg exposed coatings were recorded in real-time. The employed plate-based waveguide biosensor is applicable to monitor small molecule binding and sensitive to sub-nanometer scale changes in cell membrane position and cell mass distribution; while detecting the signals of thousands of adhering cells. The combination of this remarkable sensitivity and throughput opens up new avenues in testing complicated models of cell-surface interactions. The systematic studies revealed that, despite the reported excellent antifouling properties of the coatings, EGCg strongly interacted with them, and affected their cell adhesivity in a concentration dependent manner. Moreover, the differences between the effects of the fresh and oxidized EGCg solutions were first demonstrated. Using a semiempirical quantumchemical method we showed that EGCg binds to the PEG chains of PLL-g-PEG-RGD and effectively blocks the RGD sites by hydrogen bonds. The calculations supported the experimental finding that the binding is stronger for the oxidative products. Our work lead to a new model of polyphenol action on cell adhesion ligand accessibility and matrix rigidity.

  10. Short-lived, transitory cell-cell interactions foster migration-dependent aggregation.

    Directory of Open Access Journals (Sweden)

    Melissa D Pope

    Full Text Available During embryonic development, motile cells aggregate into cohesive groups, which give rise to tissues and organs. The role of cell migration in regulating aggregation is unclear. The current paradigm for aggregation is based on an equilibrium model of differential cell adhesivity to neighboring cells versus the underlying substratum. In many biological contexts, however, dynamics is critical. Here, we provide evidence that multicellular aggregation dynamics involves both local adhesive interactions and transport by cell migration. Using time-lapse video microscopy, we quantified the duration of cell-cell contacts among migrating cells that collided and adhered to another cell. This lifetime of cell-cell interactions exhibited a monotonic decreasing dependence on substratum adhesivity. Parallel quantitative measurements of cell migration speed revealed that across the tested range of adhesive substrata, the mean time needed for cells to migrate and encounter another cell was greater than the mean adhesion lifetime, suggesting that aggregation dynamics may depend on cell motility instead of the local differential adhesivity of cells. Consistent with this hypothesis, aggregate size exhibited a biphasic dependence on substratum adhesivity, matching the trend we observed for cell migration speed. Our findings suggest a new role for cell motility, alongside differential adhesion, in regulating developmental aggregation events and motivate new design principles for tuning aggregation dynamics in tissue engineering applications.

  11. Biocompatibility of Ir/Ti-oxide coatings: Interaction with platelets, endothelial and smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Habibzadeh, Sajjad [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Li, Ling [Department of Anatomy and Cell Biology, McGill University, Montreal, QC (Canada); Omanovic, Sasha [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Shum-Tim, Dominique [Divisions of Cardiac Surgery and Surgical Research, Department of Surgery, McGill University, Montreal, QC (Canada); Davis, Elaine C., E-mail: elaine.davis@mcgill.ca [Department of Anatomy and Cell Biology, McGill University, Montreal, QC (Canada)

    2014-05-01

    Graphical abstract: - Highlights: • Ir/Ti-oxide coated surfaces are characterized by the so-called “cracked-mud” morphology. • 40% Ir in the coating material results in a morphologically uniform coating. • ECs and SMCs showed a desirable response to the Ir/Ti-oxide coated surfaces. • Ir/Ti-oxide coated surfaces are more bio/hemocompatible than the untreated 316L stainless steel. - Abstract: Applying surface coatings on a biomedical implant is a promising modification technique which can enhance the implant's biocompatibility via controlling blood constituents- or/and cell-surface interaction. In this study, the influence of composition of Ir{sub x}Ti{sub 1−x}-oxide coatings (x = 0, 0.2, 0.4, 0.6, 0.8, 1) formed on a titanium (Ti) substrate on the responses of platelets, endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. The results showed that a significant decrease in platelet adhesion and activation was obtained on Ir{sub 0.2}Ti{sub 0.8}-oxide and Ir{sub 0.4}Ti{sub 0.6}-oxide coatings, rendering the surfaces more blood compatible, in comparison to the control (316L stainless steel, 316L-SS) and other coating compositions. Further, a substantial increase in the EC/SMC surface count ratio after 4 h of cell attachment to the Ir{sub 0.2}Ti{sub 0.8}-oxide and Ir{sub 0.4}Ti{sub 0.6}-oxide coatings, relative to the 316L-SS control and the other coating compositions, indicated high potential of these coatings for the enhancement of surface endothelialization. This indicates the capability of the corresponding coating compositions to promote EC proliferation on the surface, while inhibiting that of SMCs, which is important in cardiovascular stents applications.

  12. Plasma surface interactions in controlled fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Ghendrih, Ph.; Becoulet, M.; Costanzo, L. [and others

    2000-07-01

    This report brings together all the contributions of EURATOM/CEA association to the 14. international conference on plasma surface interactions in controlled fusion devices. 24 papers are presented and they deal mainly with the ergodic divertor and the first wall of Tore-supra tokamak.

  13. Plasma surface interactions in controlled fusion devices

    International Nuclear Information System (INIS)

    Ghendrih, Ph.; Becoulet, M.; Costanzo, L.

    2000-07-01

    This report brings together all the contributions of EURATOM/CEA association to the 14. international conference on plasma surface interactions in controlled fusion devices. 24 papers are presented and they deal mainly with the ergodic divertor and the first wall of Tore-supra tokamak

  14. Adhesive friction for elastic-plastic contacting rough surfaces considering asperity interaction

    International Nuclear Information System (INIS)

    Sahoo, Prasanta

    2006-01-01

    The paper describes a theoretical study of adhesive friction at the contact between rough surfaces taking asperity interaction into consideration and using an elastic-plastic model of contact deformation that is based on an accurate finite element analysis of an elastic-plastic single asperity contact. The micro-contact model of asperity interactions, developed by Zhao and Chang, is integrated into the improved elastic-plastic rough surface adhesive contact analysis to consider the adhesive friction behaviour of rough surfaces. The model considers a large range of interference values from fully elastic through elastic-plastic to fully plastic regimes of contacting asperities. Two well-established adhesion indices are used to consider different conditions that arise as a result of varying load, surface and material parameters. Results are obtained for the coefficient of friction against applied load for various combinations of these parameters. The results show that the coefficient of friction depends strongly on the applied load for the no-interaction case while it becomes insensitive to the load for interaction consideration. Moreover, the inclusion of elastic-plastic asperities further reduces the friction coefficient

  15. DFT study on the galvanic interaction between pyrite (100) and galena (100) surfaces

    International Nuclear Information System (INIS)

    Ke, Baolin; Li, Yuqiong; Chen, Jianhua; Zhao, Cuihua; Chen, Ye

    2016-01-01

    Graphical abstract: - Highlights: • Galvanic interaction is weakened with the increase of contact distance. • Electronic transfer mainly occurs on the contact layers. • Galvanic effect enhances nucleophilicity of galena and electrophilicity of pyrite. • Presence of H_2O increases the galvanic interaction. - Abstract: The galvanic interaction between pyrite and galena surface has been investigated using density functional theory (DFT) method. The calculated results show that galvanic interactions between pyrite and galena surface are decreased with the increase of contact distance. The galvanic interactions still occurs even the distance larger than the sum of two atoms radius (≈2.8 Å), and the limit distance of galvanic interaction between galena and pyrite surface is about 10 Å, which is consistent with the quantum tunneling effect. Through Mulliken charge population calculation, it is found that electrons transfer from galena to pyrite. For galena surface, Pb 6s and 6p states lose electrons and S 3p state loses a small amount of electrons, which causes the electron loss of galena. For pyrite surface, Fe 4p state obtains large numbers of electrons, resulting in the decrease of positive charge of Fe atom. However, the 3p state of S atom loses a small numbers of electrons. The reactivity of mineral surface has also been studied by calculating the frontier orbitals of minerals. Results suggest that the highest occupied molecular orbital (HOMO) coefficients of galena are increased whereas those of pyrite are decreased with the enhancing galvanic interaction, indicating that the oxidation of galena surface would be enhanced due to the galvanic interaction. The Fukui indices and dual descriptor values of surface atoms suggest that the nucleophilicity of the galena surface increases, meanwhile, the electrophilicity of pyrite surface increases with the decrease of the contact distance. In addition, the density of states (DOS) of atoms results show that the

  16. Soluble extracellular matrix metalloproteinase inducer (EMMPRIN, EMN) regulates cancer-related cellular functions by homotypic interactions with surface CD147.

    Science.gov (United States)

    Knutti, Nadine; Kuepper, Michael; Friedrich, Karlheinz

    2015-11-01

    EMMPRIN (extracellular matrix metalloproteinase inducer) is a widely expressed glycoprotein and a member of the immunoglobulin superfamily which exists in both a membrane-spanning and a soluble form. Homotypic interactions of EMMPRIN underlie its multiple roles in normal development and pathological situations such as viral infections, Alzheimer's disease and cancer. This study employed a recombinant soluble, fully glycosylated EMMPRIN domain (rhsEMN) as a tool to characterize the structural basis of EMMPRIN-EMMPRIN receptor (EMNR) contacts and their functional effects on MCF-7 breast carcinoma cells. rhsEMN did not form dimers in solution but bound to surface EMMPRIN (EMN) on MCF-7 cells with high affinity and was readily internalized. The interaction interface for the homotypic contact was localized to the N-terminal Ig domain. rhsEMN exerted a stimulatory effect on proliferation of MCF-7 cells whereas it reduced cell migration in a dose-dependent manner. These effects were accompanied by an upregulation of endogenous EMMPRIN as well as of matrix metalloproteinase-14 (MMP-14), a membrane-bound protease involved in the extracellular release of soluble EMMPRIN, indicating a regulatory feedback mechanism. The proliferation-promoting activity of rhsEMN was mimicked by a novel functional antibody directed to EMMPRIN, underscoring that crosslinking of cell surface EMMPRIN (EMNR) is crucial for eliciting intracellular signalling. Addressing malignancy-related signal transduction in HEK-293 cells, we could show that rhsEMN triggers the oncogenic Wnt pathway. © 2015 FEBS.

  17. Surface-modified gold nanorods for specific cell targeting

    Science.gov (United States)

    Wang, Chan-Ung; Arai, Yoshie; Kim, Insun; Jang, Wonhee; Lee, Seonghyun; Hafner, Jason H.; Jeoung, Eunhee; Jung, Deokho; Kwon, Youngeun

    2012-05-01

    Gold nanoparticles (GNPs) have unique properties that make them highly attractive materials for developing functional reagents for various biomedical applications including photothermal therapy, targeted drug delivery, and molecular imaging. For in vivo applications, GNPs need to be prepared with very little or negligible cytotoxicitiy. Most GNPs are, however, prepared using growth-directing surfactants such as cetyl trimethylammonium bromide (CTAB), which are known to have considerable cytotoxicity. In this paper, we describe an approach to remove CTAB to a non-toxic concentration. We optimized the conditions for surface modification with methoxypolyethylene glycol thiol (mPEG), which replaced CTAB and formed a protective layer on the surface of gold nanorods (GNRs). The cytotoxicities of pristine and surface-modified GNRs were measured in primary human umbilical vein endothelial cells and human cell lines derived from hepatic carcinoma cells, embryonic kidney cells, and thyroid papillary carcinoma cells. Cytotoxicity assays revealed that treating cells with GNRs did not significantly affect cell viability except for thyroid papillary carcinoma cells. Thyroid cancer cells were more susceptible to residual CTAB, so CTAB had to be further removed by dialysis in order to use GNRs for thyroid cell targeting. PEGylated GNRs are further modified to present monoclonal antibodies that recognize a specific surface marker, Na-I symporter, for thyroid cells. Antibody-conjugated GNRs specifically targeted human thyroid cells in vitro.

  18. Analysis of 4-dimethylaminopyridine (DMAP)-gold nanoparticles behaviour in solution and of their interaction with calf thymus DNA and living cells

    Energy Technology Data Exchange (ETDEWEB)

    Biver, T., E-mail: tarita@dcci.unipi.it [University of Pisa, Chemistry and Industrial Chemistry Department (Italy); Corti, A. [University of Pisa, Experimental Pathology Department BMIE (Italy); Eltugral, N. [University of Pisa, Chemistry and Industrial Chemistry Department (Italy); Lorenzini, E.; Masini, M.; Paolicchi, A. [University of Pisa, Experimental Pathology Department BMIE (Italy); Pucci, A.; Ruggeri, G.; Secco, F.; Venturini, M. [University of Pisa, Chemistry and Industrial Chemistry Department (Italy)

    2012-02-15

    4-(Dimethylamino)pyridine-coated gold nanoparticles (DMAP-Au NPs) were synthesized, characterised and their interaction with DNA and living cells was analysed. Concerning the interaction of the DMAP-Au NPs with DNA, absorbance titrations indicate that a non-covalent interaction between DNA and the external surface of the NPs does take place. The binding constant was evaluated to be (2.8 {+-} 0.8) Multiplication-Sign 10{sup 5} M{sup -1}. Exposure of cultured cells to NPs revealed a dose-dependent effect on cell proliferation which was increased or reduced in dependence of DMAP-Au NPs concentrations. Subcellular localisation by transmission electron microscopy showed mitochondrial and nuclear localisations of NPs, thus suggesting their direct involvement in the mitochondrial alterations observed and a possible direct interaction with cell DNA. These findings clearly indicate that DMAP-Au NPs can strongly interact with living cells and confirm the importance of systematic evaluations of NPs properties, also in the perspective of their arising diagnostic and therapeutic applications.

  19. Attractive interaction between an atom and a surface

    International Nuclear Information System (INIS)

    Manson, J.R.; Ritchie, R.H.

    1983-01-01

    Using a general self-energy formalism we examine the interaction between an atom and a surface. Considered in detail are deviations from the Van der Waals force due to recoil and finite velocity of the particle. Calculations for positronium near a metal surface show that for such systems recoil and velocity effects are significant even at very low energies. We also examine the mechanisms for energy exchange with the surface and calculations show that single quantum events do not always dominate the exchange rates. 8 references, 2 figures

  20. Residues essential for Panton-Valentine leukocidin S component binding to its cell receptor suggest both plasticity and adaptability in its interaction surface.

    Directory of Open Access Journals (Sweden)

    Benoit-Joseph Laventie

    Full Text Available Panton-Valentine leukocidin (PVL, a bicomponent staphylococcal leukotoxin, is involved in the poor prognosis of necrotizing pneumonia. The present study aimed to elucidate the binding mechanism of PVL and in particular its cell-binding domain. The class S component of PVL, LukS-PV, is known to ensure cell targeting and exhibits the highest affinity for the neutrophil membrane (Kd∼10(-10 M compared to the class F component of PVL, LukF-PV (Kd∼10(-9 M. Alanine scanning mutagenesis was used to identify the residues involved in LukS-PV binding to the neutrophil surface. Nineteen single alanine mutations were performed in the rim domain previously described as implicated in cell membrane interactions. Positions were chosen in order to replace polar or exposed charged residues and according to conservation between leukotoxin class S components. Characterization studies enabled to identify a cluster of residues essential for LukS-PV binding, localized on two loops of the rim domain. The mutations R73A, Y184A, T244A, H245A and Y250A led to dramatically reduced binding affinities for both human leukocytes and undifferentiated U937 cells expressing the C5a receptor. The three-dimensional structure of five of the mutants was determined using X-ray crystallography. Structure analysis identified residues Y184 and Y250 as crucial in providing structural flexibility in the receptor-binding domain of LukS-PV.

  1. Cell Adhesion on RGD-Displaying Knottins with Varying Numbers of Tryptophan Amino Acids to Tune the Affinity for Assembly on Cucurbit[8]uril Surfaces.

    Science.gov (United States)

    Sankaran, Shrikrishnan; Cavatorta, Emanuela; Huskens, Jurriaan; Jonkheijm, Pascal

    2017-09-05

    Cell adhesion is studied on multivalent knottins, displaying RGD ligands with a high affinity for integrin receptors, that are assembled on CB[8]-methylviologen-modified surfaces. The multivalency in the knottins stems from the number of tryptophan amino acid moieties, between 0 and 4, that can form a heteroternary complex with cucurbit[8]uril (CB[8]) and surface-tethered methylviologen (MV 2+ ). The binding affinity of the knottins with CB[8] and MV 2+ surfaces was evaluated using surface plasmon resonance spectroscopy. Specific binding occurred, and the affinity increased with the valency of tryptophans on the knottin. Additionally, increased multilayer formation was observed, attributed to homoternary complex formation between tryptophan residues of different knottins and CB[8]. Thus, we were able to control the surface coverage of the knottins by valency and concentration. Cell experiments with mouse myoblast (C2C12) cells on the self-assembled knottin surfaces showed specific integrin recognition by the RGD-displaying knottins. Moreover, cells were observed to elongate more on the supramolecular knottin surfaces with a higher valency, and in addition, more pronounced focal adhesion formation was observed on the higher-valency knottin surfaces. We attribute this effect to the enhanced coverage and the enhanced affinity of the knottins in their interaction with the CB[8] surface. Collectively, these results are promising for the development of biomaterials including knottins via CB[8] ternary complexes for tunable interactions with cells.

  2. Interaction between dendritic cells and natural killer cells during pregnancy in mice.

    Science.gov (United States)

    Blois, Sandra M; Barrientos, Gabriela; Garcia, Mariana G; Orsal, Arif S; Tometten, Mareike; Cordo-Russo, Rosalia I; Klapp, Burghard F; Santoni, Angela; Fernández, Nelson; Terness, Peter; Arck, Petra C

    2008-07-01

    A complex regulation of innate and adaptive immune responses at the maternal fetal interface promotes tolerance of trophoblast cells carrying paternally derived antigens. Such regulatory functions involve uterine dendritic cells (uDC) and natural killer (uNK) cells. The existence of a NK and DC "cross talk" has been revealed in various experimental settings; its biological significance ranging from cooperative stimulation to cell lysis. Little is known about the presence or role of NK and DC cross talk at the maternal fetal interface. The present study shows that mouse NK and DC interactions are subject to modulation by trophoblast cells in vitro. This interaction promotes a tolerogenic microenvironment characterized by downregulation of the expression of activation markers on uNK cells and uDC and dominance of Th2 cytokines. NK and DC interactions would also influence uterine cell proliferation and this process would be strongly modulated by trophoblast-derived signals. Indeed; while low proliferation rates were observed upon regular coculture allowing direct contact between uterine cells and trophoblasts, incubation in a transwell culture system markedly increased uterine cell proliferation suggesting that soluble factors are key mediators in the molecular "dialog" between the mother and the conceptus during the establishment of mouse pregnancy. Our data further reveal that the regulatory functions of trophoblast cells associated with tolerance induction are impaired in high abortion murine matings. Interestingly, we observed that secretion of interleukin-12p70 by uDC is dramatically abrogated in the presence of uNK cells. Taken together, our results provide the first evidence that a delicate balance of interactions involving NK cells, DC, and trophoblasts at the mouse maternal fetal interface supports a successful pregnancy outcome.

  3. Cell-surface engineering by a conjugation-and-release approach based on the formation and cleavage of oxime linkages upon mild electrochemical oxidation and reduction.

    Science.gov (United States)

    Pulsipher, Abigail; Dutta, Debjit; Luo, Wei; Yousaf, Muhammad N

    2014-09-01

    We report a strategy to rewire cell surfaces for the dynamic control of ligand composition on cell membranes and the modulation of cell-cell interactions to generate three-dimensional (3D) tissue structures applied to stem-cell differentiation, cell-surface tailoring, and tissue engineering. We tailored cell surfaces with bioorthogonal chemical groups on the basis of a liposome-fusion and -delivery method to create dynamic, electroactive, and switchable cell-tissue assemblies through chemistry involving chemoselective conjugation and release. Each step to modify the cell surface: activation, conjugation, release, and regeneration, can be monitored and modulated by noninvasive, label-free analytical techniques. We demonstrate the utility of this methodology by the conjugation and release of small molecules to and from cell surfaces and by the generation of 3D coculture spheroids and multilayered cell tissues that can be programmed to undergo assembly and disassembly on demand. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Ru-decorated Pt surfaces as model fuel cell electrocatalysts for CO electrooxidation.

    Science.gov (United States)

    Maillard, F; Lu, G-Q; Wieckowski, A; Stimming, U

    2005-09-01

    This feature article concerns Pt surfaces modified (decorated) by ruthenium as model fuel cell electrocatalysts for electrooxidation processes. This work reveals the role of ruthenium promoters in enhancing electrocatalytic activity toward organic fuels for fuel cells, and it particularly concerns the methanol decomposition product, surface CO. A special focus is on surface mobility of the CO as it is catalytically oxidized to CO(2). Different methods used to prepare Ru-decorated Pt single crystal surfaces as well as Ru-decorated Pt nanoparticles are reviewed, and the methods of characterization and testing of their activity are discussed. The focus is on the origin of peak splitting involved in the voltammetric electrooxidation of CO on Ru-decorated Pt surfaces, and on the interpretative consequences of the splitting for single crystal and nanoparticle Pt/Ru bimetallic surfaces. Apparently, screening through the literature allows formulating several models of the CO stripping reaction, and the validity of these models is discussed. Major efforts are made in this article to compare the results reported by the Urbana-Champaign group and the Munich group, but also by other groups. As electrocatalysis is progressively more and more driven by theory, our review of the experimental findings may serve to summarize the state of the art and clarify the roads ahead. Future studies will deal with highly dispersed and reactive nanoscale surfaces and other more advanced catalytic materials for fuel cell catalysis and related energy applications. It is expected that the metal/metal and metal/substrate interactions will be increasingly investigated on atomic and electronic levels, with likewise increasing participation of theory, and the structure and reactivity of various monolayer catalytic systems involving more than two metals (that is ternary and quaternary systems) will be interrogated.

  5. Engineering systems for the generation of patterned co-cultures for controlling cell-cell interactions.

    Science.gov (United States)

    Kaji, Hirokazu; Camci-Unal, Gulden; Langer, Robert; Khademhosseini, Ali

    2011-03-01

    Inside the body, cells lie in direct contact or in close proximity to other cell types in a tightly controlled architecture that often regulates the resulting tissue function. Therefore, tissue engineering constructs that aim to reproduce the architecture and the geometry of tissues will benefit from methods of controlling cell-cell interactions with microscale resolution. We discuss the use of microfabrication technologies for generating patterned co-cultures. In addition, we categorize patterned co-culture systems by cell type and discuss the implications of regulating cell-cell interactions in the resulting biological function of the tissues. Patterned co-cultures are a useful tool for fabricating tissue engineered constructs and for studying cell-cell interactions in vitro, because they can be used to control the degree of homotypic and heterotypic cell-cell contact. In addition, this approach can be manipulated to elucidate important factors involved in cell-matrix interactions. Patterned co-culture strategies hold significant potential to develop biomimetic structures for tissue engineering. It is expected that they would create opportunities to develop artificial tissues in the future. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine. 2010 Elsevier B.V. All rights reserved.

  6. HER/ErbB Receptor Interactions and Signaling Patterns in Human Mammary Epithelial Cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yi; Opresko, Lee K.; Shankaran, Harish; Chrisler, William B.; Wiley, H. S.; Resat, Haluk

    2009-10-31

    Knowledge about signaling pathways is typically compiled based on data gathered using different cell lines. This approach implicitly assumes that cell line dependence is not important, which can be misleading because different cell lines do not always respond to a particular stimulus in the same way. The lack of coherent data collected from closely related cellular systems can be detrimental to the efforts to understand the regulation of biological processes. In this study, we report the development of a library of human mammary epithelial (HME) cell lines which express endogenous levels of the cell surface receptor EGFR/HER1, and different levels of HER2 and HER3. Using our clone library, we have quantified the interactions among the HER1-3 receptors and systematically investigated the existing hypotheses about their interaction patterns. Contrary to earlier suggestions, we find that lateral interactions with HER2 do not lead to strong transactivation between EGFR and HER3. Our study identified HER2 as the dominant dimerization partner for both EGFR and HER3, and revealed that EGFR and HER3 activations are only weakly linked in HME cells. We have also quantified the time-dependent activation patterns of the downstream effectors Erk and Akt. We found that HER3 signaling makes the strongest contribution to Akt activation and that, stimulation of either EGFR or HER3 pathways activate Erk at significant levels. Our study shows that cell libraries formed from closely related clones can be a powerful resource for pursuing the quantitative investigations that are necessary for developing a systems level understanding of cell signaling.

  7. Synthesis of 3-O-sulfonated heparan sulfate octasaccharides that inhibit the herpes simplex virus type 1 host-cell interaction

    Science.gov (United States)

    Hu, Yu-Peng; Lin, Shu-Yi; Huang, Cheng-Yen; Zulueta, Medel Manuel L.; Liu, Jing-Yuan; Chang, Wen; Hung, Shang-Cheng

    2011-07-01

    Cell surface carbohydrates play significant roles in a number of biologically important processes. Heparan sulfate, for instance, is a ubiquitously distributed polysulfated polysaccharide that is involved, among other things, in the initial step of herpes simplex virus type 1 (HSV-1) infection. The virus interacts with cell-surface heparan sulfate to facilitate host-cell attachment and entry. 3-O-Sulfonated heparan sulfate has been found to function as an HSV-1 entry receptor. Achieving a complete understanding of these interactions requires the chemical synthesis of such oligosaccharides, but this remains challenging. Here, we present a convenient approach for the synthesis of two irregular 3-O-sulfonated heparan sulfate octasaccharides, making use of a key disaccharide intermediate to acquire different building blocks for the oligosaccharide chain assembly. Despite substantial structural differences, the prepared 3-O-sulfonated sugars blocked viral infection in a dosage-dependent manner with remarkable similarity to one another.

  8. Toward stimulated interaction of surface phonon polaritons

    Energy Technology Data Exchange (ETDEWEB)

    Kong, B. D.; Trew, R. J.; Kim, K. W., E-mail: kwk@ncsu.edu [Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695-7911 (United States)

    2013-12-21

    Thermal emission spectra mediated by surface phonon polariton are examined by using a theoretical model that accounts for generation processes. Specifically, the acoustic phonon fusion mechanism is introduced to remedy theoretical deficiencies of the near thermal equilibrium treatments. The model clarifies the thermal excitation mechanism of surface phonon polaritons and the energy transfer path under non-zero energy flow. When applied to GaAs and SiC semi-infinite surfaces, the nonequilibrium model predicts that the temperature dependence of the quasi-monochromatic peak can exhibit distinctly different characteristics of either sharp increase or slow saturation depending on the materials, which is in direct contrast with the estimate made by the near-equilibrium model. The proposed theoretical tool can accurately analyze the nonequilibrium steady states, potentially paving a pathway to demonstrate stimulated interaction/emission of thermally excited surface phonon polaritons.

  9. T cell motility as modulator of interactions with dendritic cells

    Directory of Open Access Journals (Sweden)

    Jens Volker Stein

    2015-11-01

    Full Text Available It is well established that the balance of costimulatory and inhibitory signals during interactions with dendritic cells (DCs determines T cell transition from a naïve to an activated or tolerant/anergic status. While many of these molecular interactions are well reproduced in reductionist in vitro assays, the highly dynamic motility of naïve T cells in lymphoid tissue acts as an additional lever to fine-tune their activation threshold. T cell detachment from DCs providing suboptimal stimulation allows them to search for DCs with higher levels of stimulatory signals, while storing a transient memory of short encounters. In turn, adhesion of weakly reactive T cells to DCs presenting pMHC with low affinity is prevented by lipid mediators. Finally, controlled recruitment of CD8+ T cells to cognate DC – CD4+ T cell clusters shapes memory T cell formation and the quality of the immune response. Dynamic physiological lymphocyte motility therefore constitutes a mechanism to mitigate low avidity T cell activation and to improve the search for optimal DCs, while contributing to peripheral tolerance induction in the absence of inflammation.

  10. Functional dynamics of cell surface membrane proteins.

    Science.gov (United States)

    Nishida, Noritaka; Osawa, Masanori; Takeuchi, Koh; Imai, Shunsuke; Stampoulis, Pavlos; Kofuku, Yutaka; Ueda, Takumi; Shimada, Ichio

    2014-04-01

    Cell surface receptors are integral membrane proteins that receive external stimuli, and transmit signals across plasma membranes. In the conventional view of receptor activation, ligand binding to the extracellular side of the receptor induces conformational changes, which convert the structure of the receptor into an active conformation. However, recent NMR studies of cell surface membrane proteins have revealed that their structures are more dynamic than previously envisioned, and they fluctuate between multiple conformations in an equilibrium on various timescales. In addition, NMR analyses, along with biochemical and cell biological experiments indicated that such dynamical properties are critical for the proper functions of the receptors. In this review, we will describe several NMR studies that revealed direct linkage between the structural dynamics and the functions of the cell surface membrane proteins, such as G-protein coupled receptors (GPCRs), ion channels, membrane transporters, and cell adhesion molecules. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Interaction of tumor cells with the microenvironment

    Directory of Open Access Journals (Sweden)

    Lehnert Hendrik

    2011-09-01

    Full Text Available Abstract Recent advances in tumor biology have revealed that a detailed analysis of the complex interactions of tumor cells with their adjacent microenvironment (tumor stroma is mandatory in order to understand the various mechanisms involved in tumor growth and the development of metastasis. The mutual interactions between tumor cells and cellular and non-cellular components (extracellular matrix = ECM of the tumor microenvironment will eventually lead to a loss of tissue homeostasis and promote tumor development and progression. Thus, interactions of genetically altered tumor cells and the ECM on the one hand and reactive non-neoplastic cells on the other hand essentially control most aspects of tumorigenesis such as epithelial-mesenchymal-transition (EMT, migration, invasion (i.e. migration through connective tissue, metastasis formation, neovascularisation, apoptosis and chemotherapeutic drug resistance. In this mini-review we will focus on these issues that were recently raised by two review articles in CCS.

  12. Crotamine and crotoxin interact with tumor cells and trigger cell death

    International Nuclear Information System (INIS)

    Soares, Marcella Araugio; Pujatti, Priscilla Brunelli; Santos, Raquel Gouvea dos; Dias, Consuelo Latorre Fortes; Chavez Olortegui, Carlos Delfin; Santos, Wagner Gouvea dos

    2007-01-01

    Crotoxin (Crtx) and Crotamine (Crota) are polypeptides isolated from Crotalus durissus terrificus snake venom (CV). Previous reports have been shown therapeutic effects of Crotalus durissus terrificus venom and Crtx on skin, breast and lung tumours, although, the mechanisms of this antitumoral effect are still unknown. The aim of this work was to investigate the antitumoral effect of Crtx and Crota on brain tumours cells (GH3 and RT2) in vitro and their capacity of interaction with these tumour cells membranes. Cell survival after Crtx and Crota treatment was evaluated by MTT assay in different times post-treatment and apoptosis was evaluated by DAPI staining. In order to evaluate the specific interaction of Crtx and Crota, these polypeptides were radiolabelled, using 125 I as radiotracer and binding assays were performed. The results were compared with the binding in nontumoral brain tissue. Crtx and Crota induced apoptosis on both tumour cells lineages but, Crota was more powerful than Crtx 90% and 20% cell death for RT2 cells; 80% and 20% cell death for GH3 cells, respectively). Both 125 I-Crtx and 125 I-Crota bound specifically in glioblastoma membranes. Nonetheless, CV polypeptides recognised glioblastoma cells with higher specificity than normal brain tissue. These results suggest that the Crtx and Crota interactions with the plasmatic membrane of tumour cells may be the first step of the cascade of signalling that trigger their antitumoral effect. (author)

  13. Asperity interaction in elastic-plastic contact of rough surfaces in presence of adhesion

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    This paper presents an analysis of the effect of asperity interaction in elastic-plastic contact of rough surfaces in the presence of adhesion. The micro-contact model of asperity interactions, developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64), is integrated into the elastic-plastic contact model developed by Roy Chowdhury and Ghosh (1994 Wear 174 9-19) to allow the asperity interaction and elastic-plastic deformation in the presence of surface forces to be considered simultaneously. The well-established elastic and plastic adhesion indices are used to consider the different conditions that arise as a result of varying load and material parameters. Results show that asperity interaction influences the loading-unloading behaviour in elastic-plastic adhesive contact of rough surfaces and in general asperity interactions reduce the effect of surface forces

  14. Interaction of hydrogen and oxygen with bulk defects and surfaces of metals

    International Nuclear Information System (INIS)

    Besenbacher, F.

    1994-05-01

    The thesis deals with the interaction of hydrogen with defects in metals and the interaction of hydrogen and oxygen with metal surfaces studied by ion-beam techniques and scanning tunneling microscopy (STM), respectively. The first part of the thesis discusses the interaction of hydrogen with simple defects in transition metals. The trap-binding enthalpies and the lattice location of hydrogen trapped to vacancies have been determined, and an extremely simple and versatile picture of the hydrogen-metal interaction has evolved, in which the trap strength is mainly determined by the local electron density. Any dilution of the lattice will lead to a trap, vacancies and voids being the strongest trap. It is found that hydrogen trapped to vacancies in fcc metals is quantum-mechanically delocalized, and the excitation energies for the hydrogen in the vacancy potential are a few MeV only. The interaction of hydrogen with metal surfaces is studied by the transmission channeling (TC) technique. It is found that hydrogen chemisorbs in the highest-coordinated sites on the surfaces, and that there is a direct relationship between the hydrogen-metal bond length and the coordination number for the hydrogen. In the final part of the thesis the dynamics of the chemisorption process for oxygen and hydrogen on metal surfaces is studied by STM, a fascinating and powerful technique for exploring the atomic-scale realm of surfaces. It is found that there is a strong coupling between the chemisorption process and the distortion of the metal surface. The adsorbates induce a surface reconstruction, i.e. metal-metal bond breaks and metal-adsorbate bounds form. Whereas hydrogen interacts weakly with the metals and induces reconstructions where only nnn metals bonds are broken, oxygen interacts strongly with the metal, and the driving force for the O-induced reconstructions appears to be the formation of low-coordinated metal-O rows, formed by breaking of nn metal bonds. Finally it is shown

  15. CD147 stimulates hepatoma cells escaping from immune surveillance of T cells by interaction with Cyclophilin A.

    Science.gov (United States)

    Ren, Yi-Xin; Wang, Shu-Jing; Fan, Jian-Hui; Sun, Shi-Jie; Li, Xia; Padhiar, Arshad Ahmed; Zhang, Jia-Ning

    2016-05-01

    T cells play an important role in tumor immune surveillance. CD147 is a member of immunoglobulin superfamily present on the surface of many tumor cells and mediates malignant cell behaviors. Cyclophilin A (CypA) is an intracellular protein promoting inflammation when released from cells. CypA is a natural ligand for CD147. In this study, CD147 specific short hairpin RNAs (shRNA) were transfected into murine hepatocellular carcinoma Hepa1-6 cells to assess the effects of CD147 on hepatoma cells escaping from immune surveillance of T cells. We found extracellular CypA stimulated cell proliferation through CD147 by activating ERK1/2 signaling pathway. Downregulation of CD147 expression on Hepa1-6 cells significantly suppressed tumor progression in vivo, and decreased cell viability when co-cultured with T cells in vitro. Importantly, knockdown of CD147 on Hepa1-6 cells resulted in significantly increased T cells chemotaxis induced by CypA both in vivo and in vitro. These findings provide novel mechanisms how tumor cells escaping from immune surveillance of T cells. We provide a potential therapy for hepatocellular carcinoma by targeting CD147 or CD147-CypA interactions. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  16. Interactions with nanoscale topography: adhesion quantification and signal transduction in cells of osteogenic and multipotent lineage.

    Science.gov (United States)

    Biggs, Manus J P; Richards, R Geoff; Gadegaard, Nikolaj; McMurray, Rebecca J; Affrossman, Stanley; Wilkinson, Chris D W; Oreffo, Richard O C; Dalby, Mathew J

    2009-10-01

    Polymeric medical devices widely used in orthopedic surgery play key roles in fracture fixation and orthopedic implant design. Topographical modification and surface micro-roughness of these devices regulate cellular adhesion, a process fundamental in the initiation of osteoinduction and osteogenesis. Advances in fabrication techniques have evolved the field of surface modification; in particular, nanotechnology has allowed the development of nanoscale substrates for the investigation into cell-nanofeature interactions. In this study human osteoblasts (HOBs) were cultured on ordered nanoscale pits and random nano "craters" and "islands". Adhesion subtypes were quantified by immunofluorescent microscopy and cell-substrate interactions investigated via immuno-scanning electron microscopy. To investigate the effects of these substrates on cellular function 1.7 k microarray analysis was used to establish gene profiles of enriched STRO-1+ progenitor cell populations cultured on these nanotopographies. Nanotopographies affected the formation of adhesions on experimental substrates. Adhesion formation was prominent on planar control substrates and reduced on nanocrater and nanoisland topographies; nanopits, however, were shown to inhibit directly the formation of large adhesions. STRO-1+ progenitor cells cultured on experimental substrates revealed significant changes in genetic expression. This study implicates nanotopographical modification as a significant modulator of osteoblast adhesion and cellular function in mesenchymal populations.

  17. The interaction of water and hydrogen with nickel surfaces

    NARCIS (Netherlands)

    Shan, Junjun

    2009-01-01

    As nickel and platinum are in the same group of the periodic table, the Ni(111) and Pt(111) surfaces may be expected to show similar interaction with water and hydrogen. However in this thesis, we show these interactions for Ni(111) are quite different from those of Pt(111). Moreover, our results

  18. Control of cell behavior on PTFE surface using ion beam irradiation

    International Nuclear Information System (INIS)

    Kitamura, Akane; Kobayashi, Tomohiro; Meguro, Takashi; Suzuki, Akihiro; Terai, Takayuki

    2009-01-01

    A polytetrafluoroethylene (PTFE) surface is smooth and biologically inert, so that cells cannot attach to it. Ion beam irradiation of the PTFE surface forms micropores and a melted layer, and the surface is finally covered with a large number of small protrusions. Recently, we found that cells could adhere to this irradiated PTFE surface and spread over the surface. Because of their peculiar attachment behavior, these surfaces can be used as biological tools. However, the factors regulating cell adhesion are still unclear, although some new functional groups formed by irradiation seem to contribute to this adhesion. To control cell behavior on PTFE surfaces, we must determine the effects of the outermost irradiated surface on cell adhesion. In this study, we removed the thin melted surface layer by postirradiation annealing and investigated cell behavior on the surface. On the surface irradiated with 3 x 10 16 ions/cm 2 , cells spread only on the remaining parts of the melted layer. From these results, it is clear that the melted layer had a capacity for cell attachment. When the surface covered with protrusions was irradiated with a fluence of 1 x 10 17 ions/cm 2 , the distribution of cells changed after the annealing process from 'sheet shaped' into multicellular aggregates with diameters of around 50 μm. These results indicate that we can control cell behavior on PTFE surfaces covered with protrusions using irradiation and subsequent annealing. Multicellular spheroids can be fabricated for tissue engineering using this surface.

  19. Biomaterials that promote cell-cell interactions enhance the paracrine function of MSCs.

    Science.gov (United States)

    Qazi, Taimoor H; Mooney, David J; Duda, Georg N; Geissler, Sven

    2017-09-01

    Mesenchymal stromal cells (MSCs) secrete paracrine factors that play crucial roles during tissue regeneration. Whether this paracrine function is influenced by the properties of biomaterials in general, and those used for cell delivery in particular, largely remains unexplored. Here, we investigated if three-dimensional culture in distinct microenvironments - nanoporous hydrogels (mean pore size ∼5 nm) and macroporous scaffolds (mean pore size ∼120 μm) - affects the secretion pattern of MSCs, and consequently leads to differential paracrine effects on target progenitor cells such as myoblasts. We report that compared to MSCs encapsulated in hydrogels, scaffold seeded MSCs show an enhanced secretion profile and exert beneficial paracrine effects on various myoblast functions including migration and proliferation. Additionally, we show that the heightened paracrine effects of scaffold seeded cells can in part be attributed to N-cadherin mediated cell-cell interactions during culture. In hydrogels, this physical interaction between cells is prevented by the encapsulating matrix. Functionally blocking N-cadherin negatively affected the secretion profile and paracrine effects of MSCs on myoblasts, with stronger effects observed for scaffold seeded compared to hydrogel encapsulated cells. Together, these findings demonstrate that the therapeutic potency of MSCs can be enhanced by biomaterials that promote cell-cell interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Plasma surface interactions in Q-enhanced mirror systems

    International Nuclear Information System (INIS)

    Post, R.F.

    1978-01-01

    Two approaches to enhancement of the Q (energy gain) factor of mirror systems are under study at Livermore. These include the Tandem Mirror and the Field Reversed Mirror. Both of these new ideas preserve features of conventional mirror systems as far as plasma-wall interactions are concerned. Specifically in both approaches field lines exit from the ends of the system and impinge on walls located at a distance from the confinement chamber. It is possible to predict some aspects of the plasma/surface interactions of TM and FRM systems from experience obtained in the Livermore 2XIIB experiment. In particular, as observed in 2XIIB, effective isolation of the plasma from thermal contact with the ends owing to the development of sheath-like regions is to be expected. Studies presently underway directed toward still further enhancing the decoupling of the plasma from the effects of plasma surface interactions at the walls will be discussed, with particular reference to the problem of minimizing the effects of refluxing secondary electrons produced by plasma impact on the end walls

  1. Integration of statistical modeling and high-content microscopy to systematically investigate cell-substrate interactions.

    Science.gov (United States)

    Chen, Wen Li Kelly; Likhitpanichkul, Morakot; Ho, Anthony; Simmons, Craig A

    2010-03-01

    Cell-substrate interactions are multifaceted, involving the integration of various physical and biochemical signals. The interactions among these microenvironmental factors cannot be facilely elucidated and quantified by conventional experimentation, and necessitate multifactorial strategies. Here we describe an approach that integrates statistical design and analysis of experiments with automated microscopy to systematically investigate the combinatorial effects of substrate-derived stimuli (substrate stiffness and matrix protein concentration) on mesenchymal stem cell (MSC) spreading, proliferation and osteogenic differentiation. C3H10T1/2 cells were grown on type I collagen- or fibronectin-coated polyacrylamide hydrogels with tunable mechanical properties. Experimental conditions, which were defined according to central composite design, consisted of specific permutations of substrate stiffness (3-144 kPa) and adhesion protein concentration (7-520 microg/mL). Spreading area, BrdU incorporation and Runx2 nuclear translocation were quantified using high-content microscopy and modeled as mathematical functions of substrate stiffness and protein concentration. The resulting response surfaces revealed distinct patterns of protein-specific, substrate stiffness-dependent modulation of MSC proliferation and differentiation, demonstrating the advantage of statistical modeling in the detection and description of higher-order cellular responses. In a broader context, this approach can be adapted to study other types of cell-material interactions and can facilitate the efficient screening and optimization of substrate properties for applications involving cell-material interfaces. Copyright 2009 Elsevier Ltd. All rights reserved.

  2. The impact of different nanoparticle surface chemistry and size on uptake and toxicity in a murine macrophage cell line

    International Nuclear Information System (INIS)

    Clift, Martin J.D.; Rothen-Rutishauser, Barbara; Brown, David M.; Duffin, Rodger; Donaldson, Ken; Proudfoot, Lorna; Guy, Keith; Stone, Vicki

    2008-01-01

    This study investigated the uptake, kinetics and cellular distribution of different surface coated quantum dots (QDs) before relating this to their toxicity. J774.A1 cells were treated with organic, COOH and NH 2 (PEG) surface coated QDs (40 nM). Model 20 nm and 200 nm COOH-modified coated polystyrene beads (PBs) were also examined (50 μg ml -1 ). The potential for uptake of QDs was examined by both fixed and live cell confocal microscopy as well as by flow cytometry over 2 h. Both the COOH 20 nm and 200 nm PBs were clearly and rapidly taken up by the J774.A1 cells, with uptake of 20 nm PBs being relatively quicker and more extensive. Similarly, COOH QDs were clearly taken up by the macrophages. Uptake of NH 2 (PEG) QDs was not detectable by live cell imaging however, was observed following 3D reconstruction of fixed cells, as well as by flow cytometry. Cells treated with organic QDs, monitored by live cell imaging, showed only a small amount of uptake in a relatively small number of cells. This uptake was insufficient to be detected by flow cytometry. Imaging of fixed cells was not possible due to a loss in cell integrity related to cytotoxicity. A significant reduction (p 2 (PEG) QDs, 20 nm and 200 nm PBs at pH 4.0 (indicative of an endosome) after 2 h, suggesting reduced stability. No evidence of exocytosis was found over 2 h. These findings confirm that surface coating has a significant influence on the mode of NP interaction with cells, as well as the subsequent consequences of that interaction

  3. Water's Interfacial Hydrogen Bonding Structure Reveals the Effective Strength of Surface-Water Interactions.

    Science.gov (United States)

    Shin, Sucheol; Willard, Adam P

    2018-06-05

    We combine all-atom molecular dynamics simulations with a mean field model of interfacial hydrogen bonding to analyze the effect of surface-water interactions on the structural and energetic properties of the liquid water interface. We show that the molecular structure of water at a weakly interacting ( i.e., hydrophobic) surface is resistant to change unless the strength of surface-water interactions are above a certain threshold. We find that below this threshold water's interfacial structure is homogeneous and insensitive to the details of the disordered surface, however, above this threshold water's interfacial structure is heterogeneous. Despite this heterogeneity, we demonstrate that the equilibrium distribution of molecular orientations can be used to quantify the energetic component of the surface-water interactions that contribute specifically to modifying the interfacial hydrogen bonding network. We identify this specific energetic component as a new measure of hydrophilicity, which we refer to as the intrinsic hydropathy.

  4. Surface force analysis of molecular interfacial interactions of proteins and lipids with polymeric biomaterials

    International Nuclear Information System (INIS)

    Hamilton-Brown, P.; Griesser, H.J.; Meagher, L.

    2001-01-01

    Full text: Adverse biological responses to biomedical devices are often caused by the irreversible accumulation of biological deposits onto the surfaces of devices. Such deposits cause blocking of artificial blood vessels, fibrous encapsulation of soft tissue regenerative devices, 'fouling' of contact lenses, secondary cataracts on intraocular lenses, and other undesirable events that interfere with the intended functions of biomedical devices. The formation of deposits is triggered by an initial stage in which various proteins and lipids rapidly adsorb onto the synthetic material surface; further biological molecules and ultimately cellular entities (e.g., host cells, bacteria) then settle onto the initial adsorbed layer. Hence, to avoid or control the accumulation of biological deposits, molecular understanding is required of the initial adsorption processes. Such adsorption is caused by attractive interfacial forces, which we are characterising by the use of a novel method. In the present study, polymeric thin film coatings, polyethylene oxide (PEO), and polysaccharide coatings have been analysed in terms of their surface forces and the ensuing propensity for protein and lipid adsorption. Interfacial forces are measured using atomic force microscopy (AFM) with a colloid-modified tip in a liquid cell using solutions of physiological pH and ionic strength. The chemical composition and uniformity of the coatings was characterised by X-ray Photon Spectroscopy (XPS). For a polymeric solid coating, repulsive forces have been measured against a silica colloid probe, and the dominant surface force is electrostatic. For the highly hydrated, 'soft' PEO and polysaccharide coatings, on the other hand, steric/entropic forces are also significant and contribute to interfacial interactions with proteins and lipids. In one system we have observed a time dependence of the electrostatic surface potential, which affects interaction with charged proteins. Force measurements were

  5. Groundwater-surface water interaction

    International Nuclear Information System (INIS)

    White, P.A.; Clausen, B.; Hunt, B.; Cameron, S.; Weir, J.J.

    2001-01-01

    This chapter discusses natural and modified interactions between groundwater and surface water. Theory on recharge to groundwater from rivers is introduced, and the relative importance of groundwater recharge from rivers is illustrated with an example from the Ngaruroro River, Hawke's Bay. Some of the techniques used to identify and measure recharge to groundwater from gravel-bed rivers will be outlined, with examples from the Ngaruroro River, where the recharge reach is relatively well defined, and from the Rakaia River, where it is poorly defined. Groundwater recharged from rivers can have characteristic chemical and isotopic signatures, as shown by Waimakariri River water in the Christchurch-West Melton groundwater system. The incorporation of groundwater-river interaction in a regional groundwater flow model is outlined for the Waimea Plains, and relationships between river scour and groundwater recharge are examined for the Waimakariri River. Springs are the result of natural discharge from groundwater systems and are important water sources. The interactions between groundwater systems, springs, and river flow for the Avon River in New Zealand will be outlined. The theory of depletion of stream flow by groundwater pumpage will be introduced with a case study from Canterbury, and salt-water intrusion into groundwater systems with examples from Nelson and Christchurch. The theory of artificial recharge to groundwater systems is introduced with a case study from Hawke's Bay. Wetlands are important to flora, and the relationship of the wetland environment to groundwater hydrology will be discussed, with an example from the South Taupo wetland. (author). 56 refs., 25 figs., 3 tabs

  6. Real-time sensing of epithelial cell-cell and cell-substrate interactions by impedance spectroscopy on porous substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, D.; RoyChaudhuri, C., E-mail: chirosreepram@yahoo.com [Department of Electronics and Telecommunication Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Pal, D. [Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India)

    2015-07-28

    Oxidized porous silicon (PS) is a common topographical biocompatible substrate that potentially provides a distinct in vitro environment for better understanding of in vivo behavior. But in the reported studies on oxidized PS, cell-cell and cell-substrate interactions have been detected only by fluorescent labeling. This paper is the first attempt to investigate real-time sensing of these interactions on HaCaT cells by label-free impedance spectroscopy on oxidized PS of two pore diameters (50 and 500 nm). One of the major requirements for successful impedance spectroscopy measurement is to restrict the channeling of electric field lines through the pores. To satisfy this criterion, we have designed the pore depths after analyzing the penetration of the medium by using computational fluid dynamics simulation. A distributed electrical model was also developed for estimating the various cellular attributes by considering a pseudorandom distribution of pores. It is observed from the impedance measurements and from the model that the proliferation rate increases for 50 nm pores but decreases for 500 nm pores compared to that for planar substrates. The rate of decrease in cell substrate separation (h) in the initial stage is more than the rate of increase in cell-cell junction resistance (R{sub b}) corresponding to the initial adhesion phase of cells. It is observed that R{sub b} and h are higher for 50 nm pores than those for planar substrates, corresponding to the fact that substrates more conducive toward cell adhesion encourage cell-cell interactions than direct cell-substrate interactions. Thus, the impedance spectroscopy coupled with the proposed theoretical framework for PS substrates can sense and quantify the cellular interactions.

  7. Real-time sensing of epithelial cell-cell and cell-substrate interactions by impedance spectroscopy on porous substrates

    International Nuclear Information System (INIS)

    Mondal, D.; RoyChaudhuri, C.; Pal, D.

    2015-01-01

    Oxidized porous silicon (PS) is a common topographical biocompatible substrate that potentially provides a distinct in vitro environment for better understanding of in vivo behavior. But in the reported studies on oxidized PS, cell-cell and cell-substrate interactions have been detected only by fluorescent labeling. This paper is the first attempt to investigate real-time sensing of these interactions on HaCaT cells by label-free impedance spectroscopy on oxidized PS of two pore diameters (50 and 500 nm). One of the major requirements for successful impedance spectroscopy measurement is to restrict the channeling of electric field lines through the pores. To satisfy this criterion, we have designed the pore depths after analyzing the penetration of the medium by using computational fluid dynamics simulation. A distributed electrical model was also developed for estimating the various cellular attributes by considering a pseudorandom distribution of pores. It is observed from the impedance measurements and from the model that the proliferation rate increases for 50 nm pores but decreases for 500 nm pores compared to that for planar substrates. The rate of decrease in cell substrate separation (h) in the initial stage is more than the rate of increase in cell-cell junction resistance (R b ) corresponding to the initial adhesion phase of cells. It is observed that R b and h are higher for 50 nm pores than those for planar substrates, corresponding to the fact that substrates more conducive toward cell adhesion encourage cell-cell interactions than direct cell-substrate interactions. Thus, the impedance spectroscopy coupled with the proposed theoretical framework for PS substrates can sense and quantify the cellular interactions

  8. Interaction of SO2 with the Surface of a Water Nanodroplet.

    Science.gov (United States)

    Zhong, Jie; Zhu, Chongqin; Li, Lei; Richmond, Geraldine L; Francisco, Joseph S; Zeng, Xiao Cheng

    2017-11-29

    We present a comprehensive computational study of interaction of a SO 2 with water molecules in the gas phase and with the surface of various sized water nanodroplets to investigate the solvation behavior of SO 2 in different atmospheric environments. Born-Oppenheimer molecular dynamics (BOMD) simulation shows that, in the gas phase and at a temperature of 300 K, the dominant interaction between SO 2 and H 2 O is (SO 2 ) S···O (H 2 O) , consistent with previous density-functional theory (DFT) computation at 0 K. However, at the surface of a water nanodroplet, BOMD simulation shows that the hydrogen-bonding interaction of (SO 2 ) O···H (H 2 O) becomes increasingly important with the increase of droplet size, reflecting a marked effect of the water surface on the SO 2 solvation. This conclusion is in good accordance with spectroscopy evidence obtained previously (J. Am. Chem. Soc. 2005, 127, 16806; J. Am. Chem. Soc. 2006, 128, 3256). The prevailing interaction (SO 2 ) O···H (H 2 O) on a large droplet is mainly due to favorable exposure of H atoms of H 2 O at the air-water interface. Indeed, the conversion of the dominant interaction in the gas phase (SO 2 ) S···O (H 2 O) to the dominant interaction on the water nanodroplet (SO 2 ) O···H (H 2 O) may incur effects on the SO 2 chemistry in atmospheric aerosols because the solvation of SO 2 at the water surface can affect the reactive sites and electrophilicity of SO 2 . Hence, the solvation of SO 2 on the aerosol surface may have new implications when studying SO 2 chemistry in the aerosol-containing troposphere.

  9. Curcumin targets fibroblast–tumor cell interactions in oral squamous cell carcinoma

    International Nuclear Information System (INIS)

    Dudás, József; Fullár, Alexandra; Romani, Angela; Pritz, Christian; Kovalszky, Ilona; Hans Schartinger, Volker; Mathias Sprinzl, Georg; Riechelmann, Herbert

    2013-01-01

    Co-culture of periodontal ligament fibroblasts (PDLs) and SCC-25 oral squamous carcinoma cells (OSCC) results in conversion of PDLs into carcinoma-associated fibroblasts (CAFs) and induces epithelial-to mesenchymal transition (EMT) of OSCC tumor cells. We hypothesized that Curcumin targets this dynamic mutual interaction between CAFs and tumor cells. Normal and 2 μM Curcumin-treated co-culture were performed for 4 days, followed by analysis of tumor cell invasivity, mRNA/protein expression of EMT-markers and mediators, activity measure of matrix metalloproteinase 9 (MMP-9), and western blot analysis of signal transduction in tumor cells and fibroblasts. In Curcumin-treated co-culture, in tumor cells, the levels of nuclear factor κB (NFκBα) and early response kinase (ERK)—decreased, in fibroblasts, integrin αv protein synthesis decreased compared to corresponding cells in normal co-culture. The signal modulatory changes induced by Curcumin caused decreased release of EMT-mediators in CAFs and reversal of EMT in tumor cells, which was associated with decreased invasion. These data confirm the palliative potential of Curcumin in clinical application. - Graphical abstract: Co-culture of periodontal ligament fibroblasts (PDLs) and SCC-25 oral squamous carcinoma cells (OSCC) results in conversion of PDLs into carcinoma-associated fibroblasts (CAFs) and induces epithelial-to mesenchymal transition (EMT) of tumor cells. Curcumin targets this dynamic mutual interaction between CAFs and tumor cells by inhibiting the production of EMT mediators in CAFs and by modification of intracellular signaling in tumor cells. This causes less invasivity and reversal of EMT in tumor cells. Highlights: ► Curcumin targets tumor–fibroblast interaction in head and neck cancer. ► Curcumin suppresses mediators of epithelial–mesenchymal transition. ► Curcumin decreases the invasivity of tumor cells

  10. Curcumin targets fibroblast–tumor cell interactions in oral squamous cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Dudás, József, E-mail: jozsef.dudas@i-med.ac.at [Department of Otorhinolaryngology and Head and Neck Surgery, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Fullár, Alexandra, E-mail: fullarsz@gmail.com [Department of Otorhinolaryngology and Head and Neck Surgery, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Üllői út 26, 1085 Budapest (Hungary); Romani, Angela, E-mail: angela.romani@i-med.ac.at [Department of Otorhinolaryngology and Head and Neck Surgery, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Pritz, Christian, E-mail: christian.pritz@i-med.ac.at [Department of Otorhinolaryngology and Head and Neck Surgery, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Kovalszky, Ilona, E-mail: koval@korb1.sote.hu [1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Üllői út 26, 1085 Budapest (Hungary); Hans Schartinger, Volker, E-mail: volker.schartinger@i-med.ac.at [Department of Otorhinolaryngology and Head and Neck Surgery, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Mathias Sprinzl, Georg, E-mail: georg.sprinzl@i-med.ac.at [Department of Otorhinolaryngology and Head and Neck Surgery, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Riechelmann, Herbert, E-mail: herbert.riechelmann@i-med.ac.at [Department of Otorhinolaryngology and Head and Neck Surgery, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria)

    2013-04-01

    Co-culture of periodontal ligament fibroblasts (PDLs) and SCC-25 oral squamous carcinoma cells (OSCC) results in conversion of PDLs into carcinoma-associated fibroblasts (CAFs) and induces epithelial-to mesenchymal transition (EMT) of OSCC tumor cells. We hypothesized that Curcumin targets this dynamic mutual interaction between CAFs and tumor cells. Normal and 2 μM Curcumin-treated co-culture were performed for 4 days, followed by analysis of tumor cell invasivity, mRNA/protein expression of EMT-markers and mediators, activity measure of matrix metalloproteinase 9 (MMP-9), and western blot analysis of signal transduction in tumor cells and fibroblasts. In Curcumin-treated co-culture, in tumor cells, the levels of nuclear factor κB (NFκBα) and early response kinase (ERK)—decreased, in fibroblasts, integrin αv protein synthesis decreased compared to corresponding cells in normal co-culture. The signal modulatory changes induced by Curcumin caused decreased release of EMT-mediators in CAFs and reversal of EMT in tumor cells, which was associated with decreased invasion. These data confirm the palliative potential of Curcumin in clinical application. - Graphical abstract: Co-culture of periodontal ligament fibroblasts (PDLs) and SCC-25 oral squamous carcinoma cells (OSCC) results in conversion of PDLs into carcinoma-associated fibroblasts (CAFs) and induces epithelial-to mesenchymal transition (EMT) of tumor cells. Curcumin targets this dynamic mutual interaction between CAFs and tumor cells by inhibiting the production of EMT mediators in CAFs and by modification of intracellular signaling in tumor cells. This causes less invasivity and reversal of EMT in tumor cells. Highlights: ► Curcumin targets tumor–fibroblast interaction in head and neck cancer. ► Curcumin suppresses mediators of epithelial–mesenchymal transition. ► Curcumin decreases the invasivity of tumor cells.

  11. Surface deformation during an action potential in pearled cells

    Science.gov (United States)

    Mussel, Matan; Fillafer, Christian; Ben-Porath, Gal; Schneider, Matthias F.

    2017-11-01

    Electric pulses in biological cells (action potentials) have been reported to be accompanied by a propagating cell-surface deformation with a nanoscale amplitude. Typically, this cell surface is covered by external layers of polymer material (extracellular matrix, cell wall material, etc.). It was recently demonstrated in excitable plant cells (Chara braunii) that the rigid external layer (cell wall) hinders the underlying deformation. When the cell membrane was separated from the cell wall by osmosis, a mechanical deformation, in the micrometer range, was observed upon excitation of the cell. The underlying mechanism of this mechanical pulse has, to date, remained elusive. Herein we report that Chara cells can undergo a pearling instability, and when the pearled fragments were excited even larger and more regular cell shape changes were observed (˜10 -100 μ m in amplitude). These transient cellular deformations were captured by a curvature model that is based on three parameters: surface tension, bending rigidity, and pressure difference across the surface. In this paper these parameters are extracted by curve-fitting to the experimental cellular shapes at rest and during excitation. This is a necessary step to identify the mechanical parameters that change during an action potential.

  12. Surface-Enhanced Raman Scattering Nanoparticles as Optical Labels for Imaging Cell Surface Proteins

    Science.gov (United States)

    MacLaughlin, Christina M.

    Assaying the expression of cell surface proteins has widespread application for characterizing cell type, developmental stage, and monitoring disease transformation. Immunophenotyping is conducted by treating cells with labelled targeting moieties that have high affinity for relevant surface protein(s). The sensitivity and specificity of immunophenotyping is defined by the choice of contrast agent and therefore, the number of resolvable signals that can be used to simultaneously label cells. Narrow band width surface-enhanced Raman scattering (SERS) nanoparticles are proposed as optical labels for multiplexed immunophenotying. Two types of surface coatings were investigated to passivate the gold nanoparticles, incorporate SERS functionality, and to facilitate attachment of targeting antibodies. Thiolated poly(ethylene glycol) forms dative bonds with the gold surface and is compatible with multiple physisorbed Raman-active reporter molecules. Ternary lipid bilayers are used to encapsulate the gold nanoparticles particles, and incorporate three different classes of Raman reporters. TEM, UV-Visible absorbance spectroscopy, DLS, and electrophoretic light scattering were used characterize the particle coating. Colourimetric protein assay, and secondary antibody labelling were used to quantify the antibody conjugation. Three different in vitromodels were used to investigate the binding efficacy and specificity of SERS labels for their biomarker targets. Primary human CLL cells, LY10 B lymphoma, and A549 adenocarcinoma lines were targeted. Dark field imaging was used to visualize the colocalization of SERS labels with cells, and evidence of receptor clustering was obtained based on colour shifts of the particles' Rayleigh scattering. Widefield, and spatially-resolved Raman spectra were used to detect labels singly, and in combination from labelled cells. Fluorescence flow cytometry was used to test the particles' binding specificity, and SERS from labelled cells was also

  13. Surface ligand dependent toxicity of zinc oxide nanoparticles in HepG2 cell model

    International Nuclear Information System (INIS)

    Bartczak, D; Baradez, M-O; Merson, S; Goenaga-Infante, H; Marshall, D

    2013-01-01

    Physicochemical properties of nanoparticles (NP) strongly affect their influence on cell behaviour, but can be significantly distorted by interactions with the proteins present in biological solutions. In this study we show how different surface functionalities of zinc oxide (ZnO) NP lead to changes in the size distribution and dissolution of the NP in serum containing cell culture media and how this impacts on NP toxicity. NPs capped with weakly bound large proteins undergo substantial transformations due to the exchange of the original surface ligands to the components of the cell culture media. Conversely, NP capped with a tight monolayer of small organic molecules or with covalently conjugated proteins show significantly higher stability. These differences in ligand exchange also affect the toxicity of the NP to the HepG2 liver cell model, with the NP capped with small organic molecules being more toxic than those capped with large proteins. This study highlights the importance of characterising NPs in biological media and the effect the media has during in-vitro analysis.

  14. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES

    Science.gov (United States)

    The interactions between agrochemicals and organo-mineral surfaces were studied using molecular mechanical conformational calculations and molecular dynamics simulations. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), 2,4-D (1, 2-dichlorophenoxyacetic acid), and DD...

  15. Schwann cell interactions with polymer films are affected by groove geometry and film hydrophilicity

    International Nuclear Information System (INIS)

    Mobasseri, S A; Downes, S; Terenghi, G

    2014-01-01

    We have developed a biodegradable polymer scaffold made of a polycaprolactone/polylactic acid (PCL/PLA) film. Surface properties such as topography and chemistry have a vital influence on cell–material interactions. Surface modifications of PCL/PLA films were performed using topographical cues and UV–ozone treatment to improve Schwann cell organisation and behaviour. Schwann cell attachment, alignment and proliferation were evaluated on the grooved UV–ozone treated and non-treated films. Solvent casting of the polymer solution on patterned silicon substrates resulted in films with different groove shapes: V (V), sloped (SL) and square (SQ) shapes. Pitted films, with no grooves, were prepared as a negative control. The UV–ozone treatment was performed to increase hydrophilicity. The process specifications for UV–ozone treatment were evaluated and 5 min radiation time and 6 cm distance to the UV source were suggested as the optimal practise. When cultured on grooved films, Schwann cells elongated on the V and SL shape grooves without crossing over, and grew in the direction of the grooves. However, there was less elongation with more crossing over on the SQ shape grooves. The maximum cell length (511 μm) was observed on the treated V-grooved films. The cells cultured on pitted UV–ozone treated surfaces showed random arrangements with no increase in length. We have demonstrated that the synergic effects of physical cues combined with UV–ozone treatment have the potential to enhance Schwann cell morphology and alignment. (paper)

  16. Affinity flow fractionation of cells via transient interactions with asymmetric molecular patterns

    Science.gov (United States)

    Bose, Suman; Singh, Rishi; Hanewich-Hollatz, Mikhail; Shen, Chong; Lee, Chia-Hua; Dorfman, David M.; Karp, Jeffrey M.; Karnik, Rohit

    2013-07-01

    Flow fractionation of cells using physical fields to achieve lateral displacement finds wide applications, but its extension to surface molecule-specific separation requires labeling. Here we demonstrate affinity flow fractionation (AFF) where weak, short-range interactions with asymmetric molecular patterns laterally displace cells in a continuous, label-free process. We show that AFF can directly draw neutrophils out of a continuously flowing stream of blood with an unprecedented 400,000-fold depletion of red blood cells, with the sorted cells being highly viable, unactivated, and functionally intact. The lack of background erythrocytes enabled the use of AFF for direct enumeration of neutrophils by a downstream detector, which could distinguish the activation state of neutrophils in blood. The compatibility of AFF with capillary microfluidics and its ability to directly separate cells with high purity and minimal sample preparation will facilitate the design of simple and portable devices for point-of-care diagnostics and quick, cost-effective laboratory analysis.

  17. IMPLICATIONS OF MICROBIAL ADHESION TO HYDROCARBONS FOR EVALUATING CELL-SURFACE HYDROPHOBICITY .1. ZETA-POTENTIALS OF HYDROCARBON DROPLETS

    NARCIS (Netherlands)

    BUSSCHER, HJ; VANDEBELTGRITTER, B; VANDERMEI, HC

    1995-01-01

    Microbial adhesion to hydrocarbons (MATH) is generally considered to be a measure of the organisms cell surface hydrophobicity. As microbial adhesion is a complicated interplay of long-range van der Waals and electrostatic forces and various short-range interactions, the above statement only holds

  18. Probing gas-surface interactions with a molecular beam

    International Nuclear Information System (INIS)

    Spruit, M.E.M.

    1988-01-01

    The dynamics of direct scattering, trapping and sticking in molecular beam scattering is probed. The O 2 /Ag interaction was chosen, using the close-packed (111) plane of Ag as target surface. 170 refs.; 22 figs.; 3 tabs

  19. Using optical tweezers for measuring the interaction forces between human bone cells and implant surfaces: System design and force calibration

    International Nuclear Information System (INIS)

    Andersson, Martin; Madgavkar, Ashwin; Stjerndahl, Maria; Wu, Yanrong; Tan, Weihong; Duran, Randy; Niehren, Stefan; Mustafa, Kamal; Arvidson, Kristina; Wennerberg, Ann

    2007-01-01

    Optical tweezers were used to study the interaction and attachment of human bone cells to various types of medical implant materials. Ideally, the implant should facilitate cell attachment and promote migration of the progenitor cells in order to decrease the healing time. It is therefore of interest, in a controlled manner, to be able to monitor the cell adhesion process. Results from such studies would help foresee the clinical outcome of integrating medical implants. The interactions between two primary cell culture models, human gingival fibroblasts and bone forming human osteoblast cells, and three different implant materials, glass, titanium, and hydroxyapatite, were studied. A novel type of optical tweezers, which has a newly designed quadrant detector and a powerful 3 W laser was constructed and force calibrated using two different methods: one method in which the stiffness of the optical trap was obtained by monitoring the phase lag between the trap and the moved object when imposing a forced oscillation on the trapped object and another method in which the maximum trapping force was derived from the critical velocity at which the object escapes the trap. Polystyrene beads as well as cells were utilized for the calibrations. This is the first time that cells have been used directly for these types of force calibrations and, hence, direct measurements of forces exerted on cells can be performed, thus avoiding the difficulties often encountered when translating the results obtained from cell measurements to the calibrations obtained with reference materials. This more straightforward approach represents an advantage in comparison to established methods

  20. Femtosecond UV-laser pulses to unveil protein-protein interactions in living cells.

    Science.gov (United States)

    Itri, Francesco; Monti, Daria M; Della Ventura, Bartolomeo; Vinciguerra, Roberto; Chino, Marco; Gesuele, Felice; Lombardi, Angelina; Velotta, Raffaele; Altucci, Carlo; Birolo, Leila; Piccoli, Renata; Arciello, Angela

    2016-02-01

    A hallmark to decipher bioprocesses is to characterize protein-protein interactions in living cells. To do this, the development of innovative methodologies, which do not alter proteins and their natural environment, is particularly needed. Here, we report a method (LUCK, Laser UV Cross-linKing) to in vivo cross-link proteins by UV-laser irradiation of living cells. Upon irradiation of HeLa cells under controlled conditions, cross-linked products of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were detected, whose yield was found to be a linear function of the total irradiation energy. We demonstrated that stable dimers of GAPDH were formed through intersubunit cross-linking, as also observed when the pure protein was irradiated by UV-laser in vitro. We proposed a defined patch of aromatic residues located at the enzyme subunit interface as the cross-linking sites involved in dimer formation. Hence, by this technique, UV-laser is able to photofix protein surfaces that come in direct contact. Due to the ultra-short time scale of UV-laser-induced cross-linking, this technique could be extended to weld even transient protein interactions in their native context.

  1. Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

    International Nuclear Information System (INIS)

    Kado, T.; Hidaka, T.; Aita, H.; Endo, K.; Furuichi, Y.

    2012-01-01

    Highlights: ► Cell-adhesive molecules were covalently immobilized on a Ti surface. ► Immobilized cell-adhesive molecules maintained native function on the Ti surface. ► Immobilized collagen enhanced adhesion of periodontal ligament cells to the Ti. - Abstract: A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully immobilized on the titanium surface and improved the compatibility of the surface

  2. Calcium phosphate thin films enhance the response of human mesenchymal stem cells to nanostructured titanium surfaces

    Directory of Open Access Journals (Sweden)

    Mura M McCafferty

    2014-05-01

    Full Text Available The development of biomaterial surfaces possessing the topographical cues that can promote mesenchymal stem cell recruitment and, in particular, those capable of subsequently directing osteogenic differentiation is of increasing importance for the advancement of tissue engineering. While it is accepted that it is the interaction with specific nanoscale topography that induces mesenchymal stem cell differentiation, the potential for an attendant bioactive chemistry working in tandem with such nanoscale features to enhance this effect has not been considered to any great extent. This article presents a study of mesenchymal stem cell response to conformal bioactive calcium phosphate thin films sputter deposited onto a polycrystalline titanium nanostructured surface with proven capability to directly induce osteogenic differentiation in human bone marrow–derived mesenchymal stem cells. The sputter deposited surfaces supported high levels of human bone marrow–derived mesenchymal stem cell adherence and proliferation, as determined by DNA quantification. Furthermore, they were also found to be capable of directly promoting significant levels of osteogenic differentiation. Specifically, alkaline phosphatase activity, gene expression and immunocytochemical localisation of key osteogenic markers revealed that the nanostructured titanium surfaces and the bioactive calcium phosphate coatings could direct the differentiation towards an osteogenic lineage. Moreover, the addition of the calcium phosphate chemistry to the topographical profile of the titanium was found to induce increased human bone marrow–derived mesenchymal stem cell differentiation compared to that observed for either the titanium or calcium phosphate coating without an underlying nanostructure. Hence, the results presented here highlight that a clear benefit can be achieved from a surface engineering strategy that combines a defined surface topography with an attendant, conformal

  3. Anisotropic Surface State Mediated RKKY Interaction Between Adatoms on a Hexagonal Lattice

    Science.gov (United States)

    Einstein, Theodore; Patrone, Paul

    2012-02-01

    Motivated by recent numerical studies of Ag on Pt(111), we derive a far-field expression for the RKKY interaction mediated by surface states on a (111) FCC surface, considering the effect of anisotropy in the Fermi edge. The main contribution to the interaction comes from electrons whose Fermi velocity vF is parallel to the vector R connecting the interacting adatoms; we show that in general, the corresponding Fermi wave-vector kF is not parallel to R. The interaction is oscillatory; the amplitude and wavelength of oscillations have angular dependence arising from the anisotropy of the surface state band structure. The wavelength, in particular, is determined by the component of the aforementioned kF that is parallel to R. Our analysis is easily generalized to other systems. For Ag on Pt(111), our results indicate that the RKKY interaction between pairs of adatoms should be nearly isotropic and so cannot account for the anisotropy found in the studies motivating our work.

  4. Influence of Cell-Cell Interactions on the Population Growth Rate in a Tumor

    Science.gov (United States)

    Chen, Yong

    2017-12-01

    The understanding of the macroscopic phenomenological models of the population growth at a microscopic level is important to predict the population behaviors emerged from the interactions between the individuals. In this work, we consider the influence of the population growth rate R on the cell-cell interaction in a tumor system and show that, in most cases especially small proliferative probabilities, the regulative role of the interaction will be strengthened with the decline of the intrinsic proliferative probabilities. For the high replication rates of an individual and the cooperative interactions, the proliferative probability almost has no effect. We compute the dependences of R on the interactions between the cells under the approximation of the nearest neighbor in the rim of an avascular tumor. Our results are helpful to qualitatively understand the influence of the interactions between the individuals on the growth rate in population systems. Supported by the National Natural Science Foundation of China under Grant Nos. 11675008 and 21434001

  5. Aerial Neutron Detection of Cosmic-Ray Interactions with the Earth's Surface

    International Nuclear Information System (INIS)

    Richard Maurer

    2008-01-01

    We have demonstrated the ability to measure the neutron flux produced by the cosmic-ray interaction with nuclei in the ground surface using aerial neutron detection. High energy cosmic-rays (primarily muons with GeV energies) interact with the nuclei in the ground surface and produce energetic neutrons via spallation. At the air-surface interface, the neutrons produced by spallation will either scatter within the surface material, become thermalized and reabsorbed, or be emitted into the air. The mean free path of energetic neutrons in air can be hundreds of feet as opposed to a few feet in dense materials. As such, the flux of neutrons escaping into the air provides a measure of the surface nuclei composition. It has been demonstrated that this effect can be measured at long range using neutron detectors on low flying helicopters. Radiological survey measurements conducted at Government Wash in Las Vegas, Nevada, have shown that the neutron background from the cosmic-soil interactions is repeatable and directly correlated to the geological data. Government Wash has a very unique geology, spanning a wide variety of nuclide mixtures and formations. The results of the preliminary measurements are presented

  6. Cell-ECM Interactions During Cancer Invasion

    Science.gov (United States)

    Jiang, Yi

    The extracellular matrix (ECM), a fibrous material that forms a network in a tissue, significantly affects many aspects of cellular behavior, including cell movement and proliferation. Transgenic mouse tumor studies indicate that excess collagen, a major component of ECM, enhances tumor formation and invasiveness. Clinically, tumor associated collagen signatures are strong markers for breast cancer survival. However, the underlying mechanisms are unclear since the properties of ECM are complex, with diverse structural and mechanical properties depending on various biophysical parameters. We have developed a three-dimensional elastic fiber network model, and parameterized it with in vitro collagen mechanics. Using this model, we study ECM remodeling as a result of local deformation and cell migration through the ECM as a network percolation problem. We have also developed a three-dimensional, multiscale model of cell migration and interaction with ECM. Our model reproduces quantitative single cell migration experiments. This model is a first step toward a fully biomechanical cell-matrix interaction model and may shed light on tumor associated collagen signatures in breast cancer. This work was partially supported by NIH-U01CA143069.

  7. Interactions between chitosan and cells measured by AFM

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, Sheng-Wen; Thien, Doan Van Hong; Ho, Ming-Hua [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10617, Taiwan (China); Hsieh, Hsyue-Jen [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Li, Chung-Hsing [Division of Orthodontics and Pediatric Dentistry, Department of Dentistry, Tri-Service General Hospital, Taipei, Taiwan (China); Hung, Chang-Hsiang [Department of Dentistry, Kinmen Hospital Department of Health, Taiwan (China); Li, Hsi-Hsin, E-mail: mhho@mail.ntust.edu.t [Deputy Superintendent, Kinmen Hospital Department of Health, Taiwan (China)

    2010-10-01

    Chitosan, a biocompatible material that has been widely used in bone tissue engineering, is believed to have a high affinity to osteoblastic cells. This research is the first to prove this hypothesis. By using atomic force microscopy (AFM) with a chitosan-modified cantilever, quantitative evaluation of the interforce between chitosan and cells was carried out. A chitosan tip functionalized with Arg-Gly-Asp (RGD) was also used to measure the interforce between RGD-chitosan and osteoblastic cells. This research concluded by examining cell adhesion and spreading of chitosan substrates as further characterization of the interactions between cells and chitosan. The force measured by AFM showed that the interforce between chitosan and osteoblasts was the highest (209 nN). The smallest adhesion force (61.8 nN) appeared between chitosan and muscle fibroblasts, which did not demonstrate any osteoblastic properties. This result proved that there was a significant interaction between chitosan and bone cells, and correlated with the observations of cell attachment and spreading. The technique developed in this research directly quantified the adhesion between chitosan and cells. This is the first study to demonstrate that specific interaction exists between chitosan and osteoblasts.

  8. Interactions between chitosan and cells measured by AFM

    International Nuclear Information System (INIS)

    Hsiao, Sheng-Wen; Thien, Doan Van Hong; Ho, Ming-Hua; Hsieh, Hsyue-Jen; Li, Chung-Hsing; Hung, Chang-Hsiang; Li, Hsi-Hsin

    2010-01-01

    Chitosan, a biocompatible material that has been widely used in bone tissue engineering, is believed to have a high affinity to osteoblastic cells. This research is the first to prove this hypothesis. By using atomic force microscopy (AFM) with a chitosan-modified cantilever, quantitative evaluation of the interforce between chitosan and cells was carried out. A chitosan tip functionalized with Arg-Gly-Asp (RGD) was also used to measure the interforce between RGD-chitosan and osteoblastic cells. This research concluded by examining cell adhesion and spreading of chitosan substrates as further characterization of the interactions between cells and chitosan. The force measured by AFM showed that the interforce between chitosan and osteoblasts was the highest (209 nN). The smallest adhesion force (61.8 nN) appeared between chitosan and muscle fibroblasts, which did not demonstrate any osteoblastic properties. This result proved that there was a significant interaction between chitosan and bone cells, and correlated with the observations of cell attachment and spreading. The technique developed in this research directly quantified the adhesion between chitosan and cells. This is the first study to demonstrate that specific interaction exists between chitosan and osteoblasts.

  9. Materiomics: deciphering topographic cues for cell-surface interactions

    NARCIS (Netherlands)

    Unadkat, H.V.

    2012-01-01

    The technological advances in the field of material science coupled with the improved understanding of cell behaviour have brought us to the era of smart or instructive biomaterials. In contrast to the bioinert materials this new generation of materials rely on the technological advances from the

  10. Dynamics of gas-surface interactions atomic-level understanding of scattering processes at surfaces

    CERN Document Server

    Díez Muniño, Ricardo

    2013-01-01

    This book gives a representative survey of the state of the art of research on gas-surface interactions. It provides an overview of the current understanding of gas surface dynamics and, in particular, of the reactive and non-reactive processes of atoms and small molecules at surfaces. Leading scientists in the field, both from the theoretical and the experimental sides, write in this book about their most recent advances. Surface science grew as an interdisciplinary research area over the last decades, mostly because of new experimental technologies (ultra-high vacuum, for instance), as well as because of a novel paradigm, the ‘surface science’ approach. The book describes the second transformation which is now taking place pushed by the availability of powerful quantum-mechanical theoretical methods implemented numerically. In the book, experiment and theory progress hand in hand with an unprecedented degree of accuracy and control. The book presents how modern surface science targets the atomic-level u...

  11. Immobilized enzymes: understanding enzyme - surface interactions at the molecular level.

    Science.gov (United States)

    Hoarau, Marie; Badieyan, Somayesadat; Marsh, E Neil G

    2017-11-22

    Enzymes immobilized on solid supports have important and industrial and medical applications. However, their uses are limited by the significant reductions in activity and stability that often accompany the immobilization process. Here we review recent advances in our understanding of the molecular level interactions between proteins and supporting surfaces that contribute to changes in stability and activity. This understanding has been facilitated by the application of various surface-sensitive spectroscopic techniques that allow the structure and orientation of enzymes at the solid/liquid interface to be probed, often with monolayer sensitivity. An appreciation of the molecular interactions between enzyme and surface support has allowed the surface chemistry and method of enzyme attachement to be fine-tuned such that activity and stability can be greatly enhanced. These advances suggest that a much wider variety of enzymes may eventually be amenable to immobilization as green catalysts.

  12. Cell surface alteration in Epstein-Barr virus-transformed cells from patients with extreme insulin resistance

    International Nuclear Information System (INIS)

    Gorden, D.L.; Robert, A.; Moncada, V.Y.; Taylor, S.I.; Muehlhauser, J.C.; Carpentier, J.L.

    1990-01-01

    An abnormality was detected in the morphology of the cell surface of Epstein-Barr virus-transformed lymphocytes of patients with genetic forms of insulin resistance. In cells from two patients with leprechaunism and two patients with type A extreme insulin resistance, scanning electron microscopy demonstrated a decrease in the percentage of the cell surface occupied by microvilli in cells from the patients with leprechaunism and type A insulin resistance compared with control cells. When cells from a healthy control subject and one of the patients with leprechaunism (Lep/Ark-1) were incubated with 125 I-labeled insulin, there was a decrease in the percentage of 125 I-insulin associated with microvilli on the cell surface. Thus, the decreased localization of insulin receptors with the microvillous region of the cell surface was in proportion to the decrease in microvilli

  13. Interactions of Condensed Tannins with Saccharomyces cerevisiae Yeast Cells and Cell Walls: Tannin Location by Microscopy.

    Science.gov (United States)

    Mekoue Nguela, Julie; Vernhet, Aude; Sieczkowski, Nathalie; Brillouet, Jean-Marc

    2015-09-02

    Interactions between grape tannins/red wine polyphenols and yeast cells/cell walls was previously studied within the framework of red wine aging and the use of yeast-derived products as an alternative to aging on lees. Results evidenced a quite different behavior between whole cells (biomass grown to elaborate yeast-derived products, inactivated yeast, and yeast inactivated after autolysis) and yeast cell walls (obtained from mechanical disruption of the biomass). Briefly, whole cells exhibited a high capacity to irreversibly adsorb grape and wine tannins, whereas only weak interactions were observed for cell walls. This last point was quite unexpected considering the literature and called into question the real role of cell walls in yeasts' ability to fix tannins. In the present work, tannin location after interactions between grape and wine tannins and yeast cells and cell walls was studied by means of transmission electron microscopy, light epifluorescence, and confocal microscopy. Microscopy observations evidenced that if tannins interact with cell walls, and especially cell wall mannoproteins, they also diffuse freely through the walls of dead cells to interact with their plasma membrane and cytoplasmic components.

  14. Physical View on the Interactions Between Cancer Cells and the Endothelial Cell Lining During Cancer Cell Transmigration and Invasion

    Science.gov (United States)

    Mierke, Claudia T.

    There exist many reviews on the biological and biochemical interactions of cancer cells and endothelial cells during the transmigration and tissue invasion of cancer cells. For the malignant progression of cancer, the ability to metastasize is a prerequisite. In particular, this means that certain cancer cells possess the property to migrate through the endothelial lining into blood or lymph vessels, and are possibly able to transmigrate through the endothelial lining into the connective tissue and follow up their invasion path in the targeted tissue. On the molecular and biochemical level the transmigration and invasion steps are well-defined, but these signal transduction pathways are not yet clear and less understood in regards to the biophysical aspects of these processes. To functionally characterize the malignant transformation of neoplasms and subsequently reveal the underlying pathway(s) and cellular properties, which help cancer cells to facilitate cancer progression, the biomechanical properties of cancer cells and their microenvironment come into focus in the physics-of-cancer driven view on the metastasis process of cancers. Hallmarks for cancer progression have been proposed, but they still lack the inclusion of specific biomechanical properties of cancer cells and interacting surrounding endothelial cells of blood or lymph vessels. As a cancer cell is embedded in a special environment, the mechanical properties of the extracellular matrix also cannot be neglected. Therefore, in this review it is proposed that a novel hallmark of cancer that is still elusive in classical tumor biological reviews should be included, dealing with the aspect of physics in cancer disease such as the natural selection of an aggressive (highly invasive) subtype of cancer cells displaying a certain adhesion or chemokine receptor on their cell surface. Today, the physical aspects can be analyzed by using state-of-the-art biophysical methods. Thus, this review will present

  15. Cell surface engineering of industrial microorganisms for biorefining applications.

    Science.gov (United States)

    Tanaka, Tsutomu; Kondo, Akihiko

    2015-11-15

    In order to decrease carbon emissions and negative environmental impacts of various pollutants, biofuel/biochemical production should be promoted for replacing fossil-based industrial processes. Utilization of abundant lignocellulosic biomass as a feedstock has recently become an attractive option. In this review, we focus on recent efforts of cell surface display using industrial microorganisms such as Escherichia coli and yeast. Cell surface display is used primarily for endowing cellulolytic activity on the host cells, and enables direct fermentation to generate useful fuels and chemicals from lignocellulosic biomass. Cell surface display systems are systematically summarized, and the drawbacks/perspectives as well as successful application of surface display for industrial biotechnology are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Surface acoustic wave actuated cell sorting (SAWACS).

    Science.gov (United States)

    Franke, T; Braunmüller, S; Schmid, L; Wixforth, A; Weitz, D A

    2010-03-21

    We describe a novel microfluidic cell sorter which operates in continuous flow at high sorting rates. The device is based on a surface acoustic wave cell-sorting scheme and combines many advantages of fluorescence activated cell sorting (FACS) and fluorescence activated droplet sorting (FADS) in microfluidic channels. It is fully integrated on a PDMS device, and allows fast electronic control of cell diversion. We direct cells by acoustic streaming excited by a surface acoustic wave which deflects the fluid independently of the contrast in material properties of deflected objects and the continuous phase; thus the device underlying principle works without additional enhancement of the sorting by prior labelling of the cells with responsive markers such as magnetic or polarizable beads. Single cells are sorted directly from bulk media at rates as fast as several kHz without prior encapsulation into liquid droplet compartments as in traditional FACS. We have successfully directed HaCaT cells (human keratinocytes), fibroblasts from mice and MV3 melanoma cells. The low shear forces of this sorting method ensure that cells survive after sorting.

  17. Measurement of the interaction between the flow and the free surface of a liquid

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Koji [Univ. of Tokyo, Ibaraki (Japan); Schmidl, W.D.; Philip, O.G. [Texas A& M Univ., College Station, TX (United States)

    1995-09-01

    The interaction between the flow and free surface was evaluated measuring the velocity distribution and surface movement simultaneously. The test section was a rectangular tank having a free surface. A rectangular nozzle was set near the free surface, causing the wavy free surface condition. The flow under the free surface was visualized by a laser light sheet and small tracer particles. With image processing techniques, the movement of the free surface and the movement of the particles were simultaneously measured from the recorded images, resulting in the velocity distributions and surface locations. Then, the interactions between the flow and free surface were evaluated using the form of turbulent energy and surface-related turbulent values. By increasing the turbulent energy near the free surface, the fluctuations of the free surface height and the inclination of the free surface were increased. The higher fluctuation of horizontal velocity was related to the higher surface position and negative inclination. The image processing technique is found to be very useful to evaluate the interaction between free surface and flow.

  18. Measurement of the interaction between the flow and the free surface of a liquid

    International Nuclear Information System (INIS)

    Okamoto, Koji; Schmidl, W.D.; Philip, O.G.

    1995-01-01

    The interaction between the flow and free surface was evaluated measuring the velocity distribution and surface movement simultaneously. The test section was a rectangular tank having a free surface. A rectangular nozzle was set near the free surface, causing the wavy free surface condition. The flow under the free surface was visualized by a laser light sheet and small tracer particles. With image processing techniques, the movement of the free surface and the movement of the particles were simultaneously measured from the recorded images, resulting in the velocity distributions and surface locations. Then, the interactions between the flow and free surface were evaluated using the form of turbulent energy and surface-related turbulent values. By increasing the turbulent energy near the free surface, the fluctuations of the free surface height and the inclination of the free surface were increased. The higher fluctuation of horizontal velocity was related to the higher surface position and negative inclination. The image processing technique is found to be very useful to evaluate the interaction between free surface and flow

  19. Fc-receptors and surface immunoglobulins in cells of the hairy cell leukemia

    International Nuclear Information System (INIS)

    Rieber, E.P.; Linke, R.P.; Riethmueller, G.; Heyden, H.W. von; Waller, H.D.

    1976-01-01

    Using 125 I-labelled aggregated IgG in a quantitative assay a strong expression of Fc-receptors was found on the leukemic cells of a patient with hairy cell leukemia. The Fc-receptor activity on these cells was much higher than that on monocytes and B-lymphocytes from normal blood. Surface immunoglobulins were detected by radioautography using radioactively labelled (Fab') 2 -fragments of monospecific antibodies directed against immunoglobulin heavy chains. Prior to radioautography the cells were stained for the tartrate resistant acid phosphatase. It is found that all cells containing this enzyme bore delta-chains on their surface. On more than 90% of these cells a simultaneous expression of μ-chains was detected. γ-chains could only be demonstrated on cells which were negative for the tartrate resistant acid phosphatase; part of these cells, however, were hairy cells by morphological criteria. (orig.) [de

  20. Fc-receptors and surface immunoglobulins in cells of the hairy cell leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Rieber, E P; Linke, R P; Riethmueller, G [Tuebingen Univ. (Germany, F.R.). Abt. fuer Experimentelle Chirurgie und Immunologie; Heyden, H.W. von; Waller, H D [Tuebingen Univ. (Germany, F.R.). Abt. Innere Medizin 2

    1976-01-01

    Using /sup 125/I-labelled aggregated IgG in a quantitative assay a strong expression of Fc-receptors was found on the leukemic cells of a patient with hairy cell leukemia. The Fc-receptor activity on these cells was much higher than that on monocytes and B-lymphocytes from normal blood. Surface immunoglobulins were detected by radioautography using radioactively labelled (Fab')/sub 2/-fragments of monospecific antibodies directed against immunoglobulin heavy chains. Prior to radioautography the cells were stained for the tartrate resistant acid phosphatase. It is found that all cells containing this enzyme bore delta-chains on their surface. On more than 90% of these cells a simultaneous expression of ..mu..-chains was detected. ..gamma..-chains could only be demonstrated on cells which were negative for the tartrate resistant acid phosphatase; part of these cells, however, were hairy cells by morphological criteria.

  1. Tumor hypoxia modulates podoplanin/CCL21 interactions in CCR7+ NK cell recruitment and CCR7+ tumor cell mobilization.

    Science.gov (United States)

    Tejchman, Anna; Lamerant-Fayel, Nathalie; Jacquinet, Jean-Claude; Bielawska-Pohl, Aleksandra; Mleczko-Sanecka, Katarzyna; Grillon, Catherine; Chouaib, Salem; Ugorski, Maciej; Kieda, Claudine

    2017-05-09

    Podoplanin (PDPN), an O-glycosylated, transmembrane, mucin-type glycoprotein, is expressed by cancer associated fibroblasts (CAFs). In malignant transformation, PDPN is subjected to changes and its role is yet to be established. Here we show that it is involved in modulating the activity of the CCL21/CCR7 chemokine/receptor axis in a hypoxia-dependent manner. In the present model, breast cancer MDA-MB-231 cells and NKL3 cells express the surface CCR7 receptor for CCL21 chemokine which is a potent chemoattractant able to bind to PDPN. The impact of the CCL21/CCR7 axis in the molecular mechanism of the adhesion of NKL3 cells and of MDA-MB-231 breast cancer cells was reduced in a hypoxic tumor environment. In addition to its known effect on migration, CCL21/CCR7 interaction was shown to allow NK cell adhesion to endothelial cells (ECs) and its reduction by hypoxia. A PDPN expressing model of CAFs made it possible to demonstrate the same CCL21/CCR7 axis involvement in the tumor cells to CAFs recognition mechanism through PDPN binding of CCL21. PDPN was induced by hypoxia and its overexpression undergoes a reduction of adhesion, making it an anti-adhesion molecule in the absence of CCL21, in the tumor. CCL21/CCR7 modulated NK cells/ECs and MDA-MB-231 cells/CAF PDPN-dependent interactions were further shown to be linked to hypoxia-dependent microRNAs as miRs: miR-210 and specifically miR-21, miR-29b which influence PDPN expression.

  2. Electromagnetic particle-in-cell simulations of the solar wind interaction with lunar magnetic anomalies.

    Science.gov (United States)

    Deca, J; Divin, A; Lapenta, G; Lembège, B; Markidis, S; Horányi, M

    2014-04-18

    We present the first three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal magnetic anomalies (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier magnetohydrodynamics and hybrid simulations, the fully kinetic nature of iPic3D allows us to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe for the first time the interaction of a dipole model centered just below the lunar surface under plasma conditions such that only the electron population is magnetized. The fully kinetic treatment identifies electromagnetic modes that alter the magnetic field at scales determined by the electron physics. Driven by strong pressure anisotropies, the mini-magnetosphere is unstable over time, leading to only temporal shielding of the surface underneath. Future human exploration as well as lunar science in general therefore hinges on a better understanding of LMAs.

  3. The cell surface expressed nucleolin is a glycoprotein that triggers calcium entry into mammalian cells

    International Nuclear Information System (INIS)

    Losfeld, Marie-Estelle; Khoury, Diala El; Mariot, Pascal; Carpentier, Mathieu; Krust, Bernard; Briand, Jean-Paul; Mazurier, Joel; Hovanessian, Ara G.; Legrand, Dominique

    2009-01-01

    Nucleolin is an ubiquitous nucleolar phosphoprotein involved in fundamental aspects of transcription regulation, cell proliferation and growth. It has also been described as a shuttling molecule between nucleus, cytosol and the cell surface. Several studies have demonstrated that surface nucleolin serves as a receptor for various extracellular ligands implicated in cell proliferation, differentiation, adhesion, mitogenesis and angiogenesis. Previously, we reported that nucleolin in the extranuclear cell compartment is a glycoprotein containing N- and O-glycans. In the present study, we show that glycosylation is an essential requirement for surface nucleolin expression, since it is prevented when cells are cultured in the presence of tunicamycin, an inhibitor of N-glycosylation. Accordingly, surface but not nuclear nucleolin is radioactively labeled upon metabolic labeling of cells with [ 3 H]glucosamine. Besides its well-demonstrated role in the internalization of specific ligands, here we show that ligand binding to surface nucleolin could also induce Ca 2+ entry into cells. Indeed, by flow cytometry, microscopy and patch-clamp experiments, we show that the HB-19 pseudopeptide, which binds specifically surface nucleolin, triggers rapid and intense membrane Ca 2+ fluxes in various types of cells. The use of several drugs then indicated that Store-Operated Ca 2+ Entry (SOCE)-like channels are involved in the generation of these fluxes. Taken together, our findings suggest that binding of an extracellular ligand to surface nucleolin could be involved in the activation of signaling pathways by promoting Ca 2+ entry into cells

  4. Local structural ordering in surface-confined liquid crystals

    Science.gov (United States)

    Śliwa, I.; Jeżewski, W.; Zakharov, A. V.

    2017-06-01

    The effect of the interplay between attractive nonlocal surface interactions and attractive pair long-range intermolecular couplings on molecular structures of liquid crystals confined in thin cells with flat solid surfaces has been studied. Extending the McMillan mean field theory to include finite systems, it has been shown that confining surfaces can induce complex orientational and translational ordering of molecules. Typically, local smectic A, nematic, and isotropic phases have been shown to coexist in certain temperature ranges, provided that confining cells are sufficiently thick, albeit finite. Due to the nonlocality of surface interactions, the spatial arrangement of these local phases can display, in general, an unexpected complexity along the surface normal direction. In particular, molecules located in the vicinity of surfaces can still be organized in smectic layers, even though nematic and/or isotropic order can simultaneously appear in the interior of cells. The resulting surface freezing of smectic layers has been confirmed to occur even for rather weak surface interactions. The surface interactions cannot, however, prevent smectic layers from melting relatively close to system boundaries, even when molecules are still arranged in layers within the central region of the system. The internal interfaces, separating individual liquid-crystal phases, are demonstrated here to form fronts of local finite-size transitions that move across cells under temperature changes. Although the complex molecular ordering in surface confined liquid-crystal systems can essentially be controlled by temperature variations, specific thermal properties of these systems, especially the nature of the local transitions, are argued to be strongly conditioned to the degree of molecular packing.

  5. Bifidobacterial surface-exopolysaccharide facilitates commensal-host interaction through immune modulation and pathogen protection

    Science.gov (United States)

    Fanning, Saranna; Hall, Lindsay J.; Cronin, Michelle; Zomer, Aldert; MacSharry, John; Goulding, David; O'Connell Motherway, Mary; Shanahan, Fergus; Nally, Kenneth; Dougan, Gordon; van Sinderen, Douwe

    2012-01-01

    Bifidobacteria comprise a significant proportion of the human gut microbiota. Several bifidobacterial strains are currently used as therapeutic interventions, claiming various health benefits by acting as probiotics. However, the precise mechanisms by which they maintain habitation within their host and consequently provide these benefits are not fully understood. Here we show that Bifidobacterium breve UCC2003 produces a cell surface-associated exopolysaccharide (EPS), the biosynthesis of which is directed by either half of a bidirectional gene cluster, thus leading to production of one of two possible EPSs. Alternate transcription of the two opposing halves of this cluster appears to be the result of promoter reorientation. Surface EPS provided stress tolerance and promoted in vivo persistence, but not initial colonization. Marked differences were observed in host immune response: strains producing surface EPS (EPS+) failed to elicit a strong immune response compared with EPS-deficient variants. Specifically, EPS production was shown to be linked to the evasion of adaptive B-cell responses. Furthermore, presence of EPS+ B. breve reduced colonization levels of the gut pathogen Citrobacter rodentium. Our data thus assigns a pivotal and beneficial role for EPS in modulating various aspects of bifidobacterial–host interaction, including the ability of commensal bacteria to remain immunologically silent and in turn provide pathogen protection. This finding enforces the probiotic concept and provides mechanistic insights into health-promoting benefits for both animal and human hosts. PMID:22308390

  6. Plasma membrane--cortical cytoskeleton interactions: a cell biology approach with biophysical considerations.

    Science.gov (United States)

    Kapus, András; Janmey, Paul

    2013-07-01

    From a biophysical standpoint, the interface between the cell membrane and the cytoskeleton is an intriguing site where a "two-dimensional fluid" interacts with an exceedingly complex three-dimensional protein meshwork. The membrane is a key regulator of the cytoskeleton, which not only provides docking sites for cytoskeletal elements through transmembrane proteins, lipid binding-based, and electrostatic interactions, but also serves as the source of the signaling events and molecules that control cytoskeletal organization and remolding. Conversely, the cytoskeleton is a key determinant of the biophysical and biochemical properties of the membrane, including its shape, tension, movement, composition, as well as the mobility, partitioning, and recycling of its constituents. From a cell biological standpoint, the membrane-cytoskeleton interplay underlies--as a central executor and/or regulator--a multitude of complex processes including chemical and mechanical signal transduction, motility/migration, endo-/exo-/phagocytosis, and other forms of membrane traffic, cell-cell, and cell-matrix adhesion. The aim of this article is to provide an overview of the tight structural and functional coupling between the membrane and the cytoskeleton. As biophysical approaches, both theoretical and experimental, proved to be instrumental for our understanding of the membrane/cytoskeleton interplay, this review will "oscillate" between the cell biological phenomena and the corresponding biophysical principles and considerations. After describing the types of connections between the membrane and the cytoskeleton, we will focus on a few key physical parameters and processes (force generation, curvature, tension, and surface charge) and will discuss how these contribute to a variety of fundamental cell biological functions. © 2013 American Physiological Society.

  7. Ephrinb1 and Ephrinb2 Are Associated with Interleukin-7 Receptor α and Retard Its Internalization from the Cell Surface*

    Science.gov (United States)

    Luo, Hongyu; Wu, Zenghui; Qi, Shijie; Jin, Wei; Han, Bing; Wu, Jiangping

    2011-01-01

    IL-7 plays vital roles in thymocyte development, T cell homeostasis, and the survival of these cells. IL-7 receptor α (IL-7Rα) on thymocytes and T cells is rapidly internalized upon IL-7 ligation. Ephrins (Efns) are cell surface molecules and ligands of the largest receptor kinase family, Eph kinases. We discovered that T cell-specific double gene knock-out (dKO) of Efnb1 and Efnb2 in mice led to reduced IL-7Rα expression in thymocytes and T cells, and that IL-7Rα down-regulation was accelerated in dKO CD4 cells upon IL-7 treatment. On the other hand, Efnb1 and Efnb2 overexpression on T cell lymphoma EL4 cells retarded IL-7Rα down-regulation. dKO T cells manifested compromised STAT5 activation and homeostatic proliferation, an IL-7-dependent process. Fluorescence resonance energy transfer and immunoprecipitation demonstrated that Efnb1 and Efnb2 interacted physically with IL-7Rα. Such interaction likely retarded IL-7Rα internalization, as Efnb1 and Efnb2 were not internalized. Therefore, we revealed a novel function of Efnb1 and Efnb2 in stabilizing IL-7Rα expression at the post-translational level, and a previously unknown modus operandi of Efnbs in the regulation of expression of other vital cell surface receptors. PMID:22069310

  8. Surface etching technologies for monocrystalline silicon wafer solar cells

    Science.gov (United States)

    Tang, Muzhi

    With more than 200 GW of accumulated installations in 2015, photovoltaics (PV) has become an important green energy harvesting method. The PV market is dominated by solar cells made from crystalline silicon wafers. The engineering of the wafer surfaces is critical to the solar cell cost reduction and performance enhancement. Therefore, this thesis focuses on the development of surface etching technologies for monocrystalline silicon wafer solar cells. It aims to develop a more efficient alkaline texturing method and more effective surface cleaning processes. Firstly, a rapid, isopropanol alcohol free texturing method is successfully demonstrated to shorten the process time and reduce the consumption of chemicals. This method utilizes the special chemical properties of triethylamine, which can form Si-N bonds with wafer surface atoms. Secondly, a room-temperature anisotropic emitter etch-back process is developed to improve the n+ emitter passivation. Using this method, 19.0% efficient screen-printed aluminium back surface field solar cells are developed that show an efficiency gain of 0.15% (absolute) compared with conventionally made solar cells. Finally, state-of-the-art silicon surface passivation results are achieved using hydrogen plasma etching as a dry alternative to the classical hydrofluoric acid wet-chemical process. The effective native oxide removal and the hydrogenation of the silicon surface are shown to be the reasons for the excellent level of surface passivation achieved with this novel method.

  9. Studies of cell biomechanics with surface micro-/nano-technology

    International Nuclear Information System (INIS)

    Wang Dong; Zhang Wei; Jiang Xingyu

    2011-01-01

    We report the recent progress in our studies of cell biology using micro-/nano-technology. Cells have a size of several to tens of microns, which makes them easily manipulated by micro-/nano-technology. The shape of the cell influences the alignment of the actin cytoskeleton, which bears the main forces of the cell, maintains the shape,and mediates a series of biochemical reactions. We invented a stretching device and studied the real-time actin filament dynamics under stretch. We found that one stretch cycle shortened the actin filaments and promoted their reassemble process. Cell migration is a complex mechanical process. We found that cell geometry determines the cell polarity and migration direction. We fabricated three-dimensional surfaces to mimic the topography in vivo, and further built a cell culture model by integrating the three-dimensional surface, microfluidics, cell patterning,and coculturing of multiple cell types. We also investigated the neuronal guidance by surface patterning. (authors)

  10. New Module to Simulate Groundwater-Surface Water Interactions in Small-Scale Alluvial Aquifer System.

    Science.gov (United States)

    Flores, L.

    2017-12-01

    Streamflow depletion can occur when groundwater pumping wells lower water table elevations adjacent to a nearby stream. Being able to accurately model the severity of this process is of critical importance in semi-arid regions where groundwater-surface water interactions affect water rights and the sustainability of water resource practices. The finite-difference flow model MODFLOW is currently the standard for estimating groundwater-surface water interactions in many regions in the western United States. However, certain limitations of the model persist when highly-resolved spatial scales are used to represent the stream-aquifer system, e.g. when the size of computational grid cells is much less than the river width. In this study, an external module is developed and linked with MODFLOW that (1) allows for multiple computational grid cells over the width of the river; (2) computes streamflow and stream stage along the length of the river using the one-dimensional (1D) steady (over a stress period) shallow water equations, which allows for more accurate stream stages when normal flow cannot be assumed or a rating curve is not available; and (3) incorporates a process for computing streamflow loss when an unsaturated zone develops under the streambed. Use of the module not only provides highly-resolved estimates of streamflow depletion, but also of streambed hydraulic conductivity. The new module is applied to the stream-aquifer alluvial system along the South Platte River south of Denver, Colorado, with results tested against field-measured groundwater levels, streamflow, and streamflow depletion.

  11. Maize EMBRYO SAC family peptides interact differentially with pollen tubes and fungal cells.

    Science.gov (United States)

    Woriedh, Mayada; Merkl, Rainer; Dresselhaus, Thomas

    2015-08-01

    EMBRYO SAC1-4 (ES1-4) peptides belong to the defensin subgroup of cysteine-rich peptides known to mediate pollen tube burst in Zea mays (maize). ES1-4 are reported here to also be capable of inhibiting germination and growth of the maize fungal pathogens Fusarium graminearum and Ustilago maydis at higher concentrations. Dividing the peptides into smaller pieces showed that a 15-amino-acid peptide located in a highly variable loop region lacking similarity to other defensins or defensin-like peptides binds to maize pollen tube surfaces, causing swelling prior to burst. This peptide fragment and a second conserved neighbouring fragment showed suppression of fungal germination and growth. The two peptides caused swelling of fungal cells, production of reactive oxygen species, and finally the formation of big vacuoles prior to burst at high peptide concentration. Furthermore, peptide fragments were found to bind differently to fungal cells. In necrotrophic F. graminearum, a peptide fragment named ES-d bound only at cell surfaces whereas the peptide ES-c bound at cell surfaces and also accumulated inside cells. Conversely, in biotrophic U. maydis, both peptide fragments accumulated inside cells, but, if applied at higher concentration, ES-c but not ES-d accumulated mainly in vacuoles. Mapping of peptide interaction sites identified amino acids differing in pollen tube burst and fungal response reactions. In summary, these findings indicate that residues targeting pollen tube burst in maize are specific to the ES family, while residues targeting fungal growth are conserved within defensins and defensin-like peptides. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  12. Surface topography of hairy cell leukemia cells compared to other leukemias as seen by scanning electron microscopy.

    Science.gov (United States)

    Polliack, Aaron; Tadmor, Tamar

    2011-06-01

    This short review deals with the ultrastructural surface architecture of hairy cell leukemia (HCL) compared to other leukemic cells, as seen by scanning electron microscopy (SEM). The development of improved techniques for preparing blood cells for SEM in the 1970s readily enabled these features to be visualized more accurately. This review returns us to the earlier history of SEM, when the surface topography of normal and neoplastic cells was visualized and reported for the first time, in an era before the emergence and use of monoclonal antibodies and flow cytometry, now used routinely to define cells by their immunophenotype. Surface microvilli are characteristic for normal and leukemic lymphoid cells, myelo-monocytic cells lack microvilli and show surface ruffles, while leukemic plasma and myeloma cells and megakaryocytes display large surface blebs. HCL cell surfaces are complex and typically 'hybrid' in nature, displaying both lymphoid and monocytic features with florid ruffles of varying sizes interspersed with clumps of short microvilli cytoplasm. The surface features of other leukemic cells and photomicrographs of immuno-SEM labeling of cells employing antibodies and colloidal gold, reported more than 20 years ago, are shown.

  13. Yeast cell surface display for lipase whole cell catalyst and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yun; Zhang, Rui; Lian, Zhongshuai; Wang, Shihui; Wright, Aaron T.

    2014-08-01

    The cell surface display technique allows for the expression of target proteins or peptides on the microbial cell surface by fusing an appropriate protein as an anchoring motif. Yeast display systems, such as Pichia pastoris, Yarowia lipolytica and Saccharomyces cerevisiae, are ideal, alternative and extensive display systems with the advantage of simple genetic manipulation and post-translational modification of expressed heterologous proteins. Engineered yeasts show high performance characteristics and variant utilizations. Herein, we comprehensively summarize the variant factors affecting lipase whole cell catalyst activity and display efficiency, including the structure and size of target proteins, screening anchor proteins, type and chain length of linkers, and the appropriate matching rules among the above-mentioned display units. Furthermore, we also address novel approaches to enhance stability and activity of recombinant lipases, such as VHb gene co-expression, multi-enzyme co-display technique, and the micro-environmental interference and self-assembly techniques. Finally, we represent the variety of applications of whole cell surface displayed lipases on yeast cells in non-aqueous phases, including synthesis of esters, PUFA enrichment, resolution of chiral drugs, organic synthesis and biofuels. We demonstrate that the lipase surface display technique is a powerful tool for functionalizing yeasts to serve as whole cell catalysts, and increasing interest is providing an impetus for broad application of this technique.

  14. Interaction of a snake venom L-amino acid oxidase with different cell types membrane.

    Science.gov (United States)

    Abdelkafi-Koubaa, Zaineb; Aissa, Imen; Morjen, Maram; Kharrat, Nadia; El Ayeb, Mohamed; Gargouri, Youssef; Srairi-Abid, Najet; Marrakchi, Naziha

    2016-01-01

    Snake venom l-amino acid oxidases are multifunctional enzymes that exhibited a wide range of pharmacological activities. Although it has been established that these activities are primarily caused by the H2O2 generated in the enzymatic reaction, the molecular mechanism, however, has not been fully investigated. In this work, LAAO interaction with cytoplasmic membranes using different cell types and Langmuir interfacial monolayers was evaluated. The Cerastes cerastes venom LAAO (CC-LAAO) did not exhibit cytotoxic activities against erythrocytes and peripheral blood mononuclear cells (PBMC). However, CC-LAAO caused cytotoxicity on several cancer cell lines and induced platelet aggregation in dose-dependent manner. Furthermore, the enzyme showed remarkable effect against Gram-positive and Gram-negative bacteria. These activities were inhibited on the addition of catalase or substrate analogs, suggesting that H2O2 liberation× is required for these effects. Binding studies revealed that CC-LAAO binds to the cell surface and enables the production of highly localized concentration of H2O2 in or near the binding interfaces. On another hand, the interaction of CC-LAAO with a mimetic phospholipid film was evaluated, for the first time, using a monomolecular film technique. Results indicated that phospholipid/CC-LAAO interactions are not involved in their binding to membrane and in their pharmacological activities. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Interaction between D-fructose dehydrogenase and methoxy-substituent-functionalized carbon surface to increase productive orientations

    International Nuclear Information System (INIS)

    Xia, Hong-qi; Hibino, Yuya; Kitazumi, Yuki; Shirai, Osamu; Kano, Kenji

    2016-01-01

    Highlights: • Methoxy-functionalized surface improves the DET-type bioelectrocatalysis of FDH. • Methoxy-functionalized surface increases productive orientations. • The total catalytic activity of FDH is almost independent of the modification. • High current density as well as good stability is useful for biofuel cells. - Abstract: D-Fructose dehydrogenase (FDH) from Gluconobacter japonicus NBRC3260 catalyzes the two-electron oxidation of D-fructose to 5-keto-D-fructose, and it is widely used in biofuel cells and biosensors. In this study, methoxy-substituent-functionalized carbon electrodes are constructed by electrochemical oxidation of methoxy-aniline derivatives on Ketjen Black (KB)-modified electrodes to improve the immobilization and bioelectrocatalysis of FDH. It is proposed that the specific interaction between FDH, especially the heme c moiety, and methoxy substituent(s) of amines on carbon electrode increases the proportion of the productively oriented FDH molecules to the total FDHs. Consequently, the limiting catalytic current density of the D-fructose oxidation increases to as much as 23 ± 2 mA cm −2 in FDH/2,4-dimethoxyaniline/KB/glassy carbon electrode, for example.

  16. Investigation of back surface fields effect on bifacial solar cells

    Science.gov (United States)

    Sepeai, Suhaila; Sulaiman, M. Y.; Sopian, Kamaruzzaman; Zaidi, Saleem H.

    2012-11-01

    A bifacial solar cell, in contrast with a conventional monofacial solar cell, produces photo-generated current from both front and back sides. Bifacial solar cell is an attractive candidate for enhancing photovoltaic (PV) market competitiveness as well as supporting the current efforts to increase efficiency and lower material costs. This paper reports on the fabrication of bifacial solar cells using phosphorus-oxytrichloride (POCl3) emitter formation on p-type, nanotextured silicon (Si) wafer. Backside surface field was formed through Al-diffusion using conventional screen-printing process. Bifacial solar cells with a structure of n+pp+ with and without back surface field (BSF) were fabricated in which silicon nitride (SiN) anti reflection and passivation films were coated on both sides, followed by screen printing of Argentum (Ag) and Argentum/Aluminum (Ag/Al) on front and back contacts, respectively. Bifacial solar cells without BSF exhibited open circuit voltage (VOC) of 535 mV for front and 480 mV for back surface. With Al-alloyed BSF bifacial solar cells, the VOC improved to 580 mV for the front surface and 560 mV for the back surface. Simulation of bifacial solar cells using PC1D and AFORS software demonstrated good agreement with experimental results. Simulations showed that best bifacial solar cells are achieved through a combination of high lifetime wafer, low recombination back surface field, reduced contact resistance, and superior surface passivation.

  17. F2 excimer laser (157 nm) radiation modification and surface ablation of PHEMA hydrogels and the effects on bioactivity: Surface attachment and proliferation of human corneal epithelial cells

    International Nuclear Information System (INIS)

    Zainuddin; Chirila, Traian V.; Barnard, Zeke; Watson, Gregory S.; Toh, Chiong; Blakey, Idriss; Whittaker, Andrew K.; Hill, David J.T.

    2011-01-01

    Physical and chemical changes at the surface of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels modified by ablation with an F 2 excimer laser were investigated experimentally. An important observation was that only the outer exposed surface layers of the hydrogel were affected by the exposure to 157 nm radiation. The effect of the surface changes on the tendency of cells to adhere to the PHEMA was also investigated. A 0.5 cm 2 area of the hydrogel surfaces was exposed to laser irradiation at 157 nm to fluences of 0.8 and 4 J cm -2 . The changes in surface topography were analysed by light microscopy and atomic force microscopy, while the surface chemistry was characterized by attenuated total reflection infrared and X-ray photoelectron spectroscopies. Cell-interfacial interactions were examined based on the proliferation of human corneal limbal epithelial (HLE) cells cultured on the laser-modified hydrogels, and on the unexposed hydrogels and tissue culture plastic for comparison. It was observed that the surface topography of laser-exposed hydrogels showed rippled patterns with a surface roughness increasing at the higher exposure dose. The changes in surface chemistry were affected not only by an indirect effect of hydrogen and hydroxyl radicals, formed by water photolysis, on the PHEMA, but also by the direct action of laser radiation on PHEMA if the surface layers of the gel become depleted of water. The laser treatment led to a change in the surface characteristics, with a lower concentration of ester side-chains and the formation of new oxygenated species at the surface. The surface also became more hydrophobic. Most importantly, the surface chemistry and the newly created surface topographical features were able to improve the attachment, spreading and growth of HLE cells.

  18. Anisotropic surface-state-mediated RKKY interaction between adatoms on a hexagonal lattice

    Science.gov (United States)

    Patrone, Paul N.; Einstein, T. L.

    2012-01-01

    Motivated by recent numerical studies of Ag on Pt(111), we derive an expression for the RKKY interaction mediated by surface states, considering the effect of anisotropy in the Fermi edge. Our analysis is based on a stationary phase approximation. The main contribution to the interaction comes from electrons whose Fermi velocity vF is parallel to the vector R connecting the interacting adatoms; we show that, in general, the corresponding Fermi wave vector kF is not parallel to R. The interaction is oscillatory; the amplitude and wavelength of oscillations have angular dependence arising from the anisotropy of the surface-state band structure. The wavelength, in particular, is determined by the projection of this kF (corresponding to vF) onto the direction of R. Our analysis is easily generalized to other systems. For Ag on Pt(111), our results indicate that the RKKY interaction between pairs of adatoms should be nearly isotropic and so cannot account for the anisotropy found in the studies motivating our work. However, for metals with surface-state dispersions similar to Be(101¯0), we show that the RKKY interaction should have considerable anisotropy.

  19. Interactions between yeasts and bacteria in the smear surface-ripened cheeses.

    Science.gov (United States)

    Corsetti, A; Rossi, J; Gobbetti, M

    2001-09-19

    In the initial phase of ripening, the microflora of bacterial smear surface-ripened cheeses such as Limburger, Taleggio, Brick, Münster and Saint-Paulin and that of surface mould-ripened cheeses such as Camembert and Brie may be similar, but at the end of the ripening, bacteria such as Brevibacterium spp., Arthrobacter spp., Micrococcus spp., Corynebacterium spp. and moulds such as Penicillium camemberti are, respectively, the dominant microorganisms. Yeasts such as Candida spp., Cryptococcus spp., Debaryomyces spp., Geotrichum candidum, Pichia spp., Rhodotorula spp., Saccharomyces spp. and Yarrowia lipolytica are often and variably isolated from the smear surface-ripened cheeses. Although not dominant within the microorganisms of the smear surface-ripened cheeses, yeasts establish significant interactions with moulds and especially bacteria, including surface bacteria and lactic acid bacteria. Some aspects of the interactions between yeasts and bacteria in such type of cheeses are considered in this paper.

  20. Visualization and targeted disruption of protein interactions in living cells

    Science.gov (United States)

    Herce, Henry D.; Deng, Wen; Helma, Jonas; Leonhardt, Heinrich; Cardoso, M. Cristina

    2013-01-01

    Protein–protein interactions are the basis of all processes in living cells, but most studies of these interactions rely on biochemical in vitro assays. Here we present a simple and versatile fluorescent-three-hybrid (F3H) strategy to visualize and target protein–protein interactions. A high-affinity nanobody anchors a GFP-fusion protein of interest at a defined cellular structure and the enrichment of red-labelled interacting proteins is measured at these sites. With this approach, we visualize the p53–HDM2 interaction in living cells and directly monitor the disruption of this interaction by Nutlin 3, a drug developed to boost p53 activity in cancer therapy. We further use this approach to develop a cell-permeable vector that releases a highly specific peptide disrupting the p53 and HDM2 interaction. The availability of multiple anchor sites and the simple optical readout of this nanobody-based capture assay enable systematic and versatile analyses of protein–protein interactions in practically any cell type and species. PMID:24154492

  1. Plasma surface interaction studies in Japan

    International Nuclear Information System (INIS)

    Hino, T.; Hirohata, Y.; Yamashina, T.

    1994-01-01

    In order to achieve a long burning time period in a fusion reactor, the interactions between the plasma facing materials and the fusion plasma have to be well controlled. Namely, the radiation loss due to impurities and deterioration of the energy confinement time due to fuel particle recyclings have to be suppressed, in addition to the requirement of heat removal based on a high heat flux component. Recently, in Japan, the plasma facing material/component has been very actively developed for ITER and Large Helical Device (LHD). In this review paper, we briefly introduce the following issues, (1) progress of plasma surface interactions in tokamaks and helical devices, (2) development of plasma facing materials, (3) divertor development, (4) boronization, (5) selective pumping of helium ash, (6) tritium retention, and (7) neutron damage of graphite plasma facing material. (author)

  2. MILD CHOLESTEROL DEPLETION REDUCES AMYLOID-β PRODUCTION BY IMPAIRING APP TRAFFICKING TO THE CELL SURFACE

    Science.gov (United States)

    Guardia-Laguarta, Cristina; Coma, Mireia; Pera, Marta; Clarimón, Jordi; Sereno, Lidia; Agulló, José M.; Molina-Porcel, Laura; Gallardo, Eduard; Deng, Amy; Berezovska, Oksana; Hyman, Bradley T.; Blesa, Rafael; Gómez-Isla, Teresa; Lleó, Alberto

    2009-01-01

    It has been suggested that cellular cholesterol levels can modulate the metabolism of the amyloid precursor protein (APP) but the underlying mechanism remains controversial. In the current study, we investigate in detail the relationship between cholesterol reduction, APP processing and γ-secretase function in cell culture studies. We found that mild membrane cholesterol reduction led to a decrease in Aβ40 and Aβ42 in different cell types. We did not detect changes in APP intracellular domain or Notch intracellular domain generation. Western blot analyses showed a cholesterol-dependent decrease in the APP C-terminal fragments and cell surface APP. Finally, we applied a fluorescence resonance energy transfer (FRET)-based technique to study APP-Presenilin 1 (PS1) interactions and lipid rafts in intact cells. Our data indicate that cholesterol depletion reduces association of APP into lipid rafts and disrupts APP-PS1 interaction. Taken together, our results suggest that mild membrane cholesterol reduction impacts the cleavage of APP upstream of γ-secretase and appears to be mediated by changes in APP trafficking and partitioning into lipid rafts. PMID:19457132

  3. Comprehensive studies on the interactions between chitosan nanoparticles and some live cells

    International Nuclear Information System (INIS)

    Zheng Aiping; Liu Huixue; Yuan Lan; Meng Meng; Wang Jiancheng; Zhang Xuan; Zhang Qiang

    2011-01-01

    As more and more oral formulations of nanoparticles are used in clinical contexts, a comprehensive study on the mechanisms of interaction between polymer nanoparticles and live cells seems merited. Such a study was conducted and the results were compared to the polymer itself in order to demonstrate different kinds of effects that are brought into the cell by polymer and its nanoparticles, especially the effects on the biomembrane. Several techniques, including surface plasmon resonance (SPR), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, fluorescence polarization spectroscopy (FP), flow cytometry (FCM) with quantitative analysis, and confocal images with antibody staining were employed toward this end. The cytotoxicity in vitro was also evaluated. Chitosan (CS), a polycationic polymer, was used to prepare the nanoparticles. We demonstrate that chitosan nanoparticles (CS-NP) induce strong alterations in the distribution of membrane proteins, fluidity of membrane lipids, and general membrane structure. Furthermore, the uptake of CS-NP into Caco-2 cells was found to have a similar mechanism to that of CS molecules, but the differences in degree were noted. These results indicate that positive charge and nanoscale size were the factors that most significantly affected the interactions between the nanoparticles of polycationic polymers and live cells. However, no difference in cytotoxicity toward the Caco-2 cells was found between CS and CS-NP. This supports the idea that CS-NP is an effective and safe carrier for oral drug delivery.

  4. UV and IR laser radiation's interaction with metal film and teflon surfaces

    Science.gov (United States)

    Fedenev, A. V.; Alekseev, S. B.; Goncharenko, I. M.; Koval', N. N.; Lipatov, E. I.; Orlovskii, V. M.; Shulepov, M. A.; Tarasenko, V. F.

    2003-04-01

    The interaction of Xe ([lambda] [similar] 1.73 [mu]m) and XeCl (0.308 [mu]m) laser radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion versus laser-specific energy was investigated. Monitoring of laser-induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over the laser beam cross section allowing evaluation of defects and adhesion of coatings. The interaction of pulsed periodical CO2 ([lambda] [similar] 10.6 [mu]m), and Xe ([lambda] [similar] 1.73 [mu]m) laser radiation with surfaces of teflon (polytetrafluoroethylene—PTFE) has been studied. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO2-radiation interaction with teflon the sputtering of polymer with formation of submicron-size particles occurs. Dependencies of particle sizes, form, and sputtering velocity on laser pulse duration and target temperature have been obtained.

  5. Interaction of dyes CD–1 and SD–1 with the surface of oligodimethysiloxane

    Science.gov (United States)

    Chausov, D. N.

    2018-03-01

    We carried out the modeling orientation of the dyes CD–1 and SD–1 relative to the surface of oligodimethysiloxane using the atom–atom potentials method. We have discovered the dependence of the interaction energy in dyes molecules on the angles which characterizes their orientation relative to the surface of the oligodimethysiloxane crystal. It was found out that the obtained energy value of interaction with the surface can explain weak adhesive qualities of the dyes and the orientation type relative to the surface. We identified the break– loose force for the dyes on the oligodimethysiloxane crystal surface.

  6. A novel multistep method for chondroitin sulphate immobilization and its interaction with fibroblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Ozaltin, Kadir; Lehocký, Marián, E-mail: lehocky@post.cz; Kuceková, Zdenka; Humpolíček, Petr; Sáha, Petr

    2017-01-01

    Polymeric biomaterials are widely used in medical applications owing to their low cost, processability and sufficient toughness. Surface modification by creating a thin film of bioactive agents is promising technique to enhance cellular interactions, regulate the protein adsorption and/or avoid bacterial infections. Polyethylene is one of the most used polymeric biomaterial but its hydrophobic nature impedes its further chemical modifications. Plasma treatment is unique method to increase its hydrophilicity by incorporating hydrophilic oxidative functional groups and tailoring the surface by physical etching. Furthermore, grafting of polymer brushes of amine group containing monomers onto the functionalized surface lead to strongly immobilized bioactive agents at the final step. Chondroitin sulphate is natural polysaccharide mainly found in connective cartilage tissue which used as a bioactive agent to immobilize onto polyethylene surface by multistep method in this study. - Highlights: • Attachment of chondroitin sulfate to polyethylene. • A robust way to modify surfaces using multistep approach. • The modified surfaces showed improved proliferation of mouse primary fibroblast cells.

  7. Concise Review: Cell Surface N-Linked Glycoproteins as Potential Stem Cell Markers and Drug Targets.

    Science.gov (United States)

    Boheler, Kenneth R; Gundry, Rebekah L

    2017-01-01

    Stem cells and their derivatives hold great promise to advance regenerative medicine. Critical to the progression of this field is the identification and utilization of antibody-accessible cell-surface proteins for immunophenotyping and cell sorting-techniques essential for assessment and isolation of defined cell populations with known functional and therapeutic properties. Beyond their utility for cell identification and selection, cell-surface proteins are also major targets for pharmacological intervention. Although comprehensive cell-surface protein maps are highly valuable, they have been difficult to define until recently. In this review, we discuss the application of a contemporary targeted chemoproteomic-based technique for defining the cell-surface proteomes of stem and progenitor cells. In applying this approach to pluripotent stem cells (PSCs), these studies have improved the biological understanding of these cells, led to the enhanced use and development of antibodies suitable for immunophenotyping and sorting, and contributed to the repurposing of existing drugs without the need for high-throughput screening. The utility of this latter approach was first demonstrated with human PSCs (hPSCs) through the identification of small molecules that are selectively toxic to hPSCs and have the potential for eliminating confounding and tumorigenic cells in hPSC-derived progeny destined for research and transplantation. Overall, the cutting-edge technologies reviewed here will accelerate the development of novel cell-surface protein targets for immunophenotyping, new reagents to improve the isolation of therapeutically qualified cells, and pharmacological studies to advance the treatment of intractable diseases amenable to cell-replacement therapies. Stem Cells Translational Medicine 2017;6:131-138. © 2016 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

  8. Surface Traps in Colloidal Quantum Dot Solar Cells, their Mitigation and Impact on Manufacturability

    KAUST Repository

    Kirmani, Ahmad R.

    2017-07-30

    Colloidal quantum dots (CQDs) are potentially low-cost, solution-processable semiconductors which are endowed, through their nanoscale dimensions, with strong absorption, band gap tunability, high dielectric constants and enhanced stability. CQDs are contenders as a standalone PV technology as well as a potential back layer for augmenting established photovoltaic (PV) technologies, such as Si. However, owing to their small size (ca. few nanometers), CQDs are prone to surface trap states that inhibit charge transport and threaten their otherwise wonderful optoelectronic properties. Surface traps have also, indirectly, impeded scalable and industry-compatible fabrication of these solar cells, as all of the reports, to date, have relied on spin-coating with sophisticated and tedious ligand exchange schemes, some of which need to be performed in low humidity environments. In this thesis, we posit that an in-depth understanding of the process-structure-property-performance relationship in CQDs can usher in fresh insights into the nature and origin of surface traps, lead to novel ways to mitigate them, and finally help achieve scalable fabrication. To this end, we probe the CQD surfaces and their interactions with process solvents, linkers, and ambient environment employing a suite of spectroscopic techniques. These fundamental insights help us develop facile chemical and physical protocols to mitigate surface traps such as solvent engineering, remote molecular doping, and oxygen doping, directly leading to better-performing solar cells. Our efforts finally culminate in the realization of >10% efficient, air-stable CQD solar cells scalably fabricated in an ambient environment of high, uncontrolled R.H. (50-65%). As-prepared solar cells fabricated in high humidity ambient conditions are found to underperform, however, an oxygen-doping recipe is devised to mitigate the moisture-induced surface traps and recover device performances. Importantly, these solar cells are

  9. Blast wave interaction with a rigid surface

    International Nuclear Information System (INIS)

    Josey, T.; Whitehouse, D.R.; Ripley, R.C.; Dionne, J.P.

    2004-01-01

    A simple model used to investigate blast wave interactions with a rigid surface is presented. The model uses a constant volume energy source analogue to predict pressure histories at gauges located directly above the charge. A series of two-dimensional axi-symmetric CFD calculations were performed, varying the height of the charge relative to the ground. Pressure histories, along with isopycnic plots are presented to evaluate the effects of placing a charge in close proximity to a rigid surface. When a charge is placed near a solid surface the pressure histories experienced at gauges above the charge indicate the presence of two distinct pressure peaks. The first peak is caused by the primary shock and the second peak is a result of the wave reflections from the rigid surface. As the distance from the charge to the wall is increased the magnitude of the second pressure peak is reduced, provided that the distance between the charge and the gauge is maintained constant. The simple model presented is able to capture significant, predictable flow features. (author)

  10. Basic reactions of osteoblasts on structured material surfaces

    Directory of Open Access Journals (Sweden)

    U. Meyer

    2005-04-01

    Full Text Available In order to assess how bone substitute materials determine bone formation in vivo it is useful to understand the mechanisms of the material surface/tissue interaction on a cellular level. Artificial materials are used in two applications, as biomaterials alone or as a scaffold for osteoblasts in a tissue engineering approach. Recently, many efforts have been undertaken to improve bone regeneration by the use of structured material surfaces. In vitro studies of bone cell responses to artificial materials are the basic tool to determine these interactions. Surface properties of materials surfaces as well as biophysical constraints at the biomaterial surface are of major importance since these features will direct the cell responses. Studies on osteoblast-like cell reactivity towards materials will have to focus on the different steps of protein and cell reactions towards defined surface properties. The introduction of new techniques allows nowadays the fabrication of materials with ordered surface structures. This paper gives a review of present knowledge on the various stages of osteoblast reactions on material surfaces, focused on basic cell events under in vitro conditions. Special emphasis is given to cellular reactions towards ordered nano-sized topographies.

  11. Interaction Mechanisms between Air Bubble and Molybdenite Surface: Impact of Solution Salinity and Polymer Adsorption.

    Science.gov (United States)

    Xie, Lei; Wang, Jingyi; Yuan, Duowei; Shi, Chen; Cui, Xin; Zhang, Hao; Liu, Qi; Liu, Qingxia; Zeng, Hongbo

    2017-03-07

    The surface characteristics of molybdenite (MoS 2 ) such as wettability and surface interactions have attracted much research interest in a wide range of engineering applications, such as froth flotation. In this work, a bubble probe atomic force microscope (AFM) technique was employed to directly measure the interaction forces between an air bubble and molybdenite mineral surface before/after polymer (i.e., guar gum) adsorption treatment. The AFM imaging showed that the polymer coverage on the surface of molybdenite could achieve ∼5.6, ∼44.5, and ∼100% after conditioning in 1, 5, and 10 ppm polymer solution, respectively, which coincided with the polymer coverage results based on contact angle measurements. The electrolyte concentration and surface treatment by polymer adsorption were found to significantly affect bubble-mineral interaction and attachment. The experimental force results on bubble-molybdenite (without polymer treatment) agreed well with the calculations using a theoretical model based on the Reynolds lubrication theory and augmented Young-Laplace equation including the effect of disjoining pressure. The overall surface repulsion was enhanced when the NaCl concentration decreased from 100 to 1 mM, which inhibited the bubble-molybdenite attachment. After conditioning the molybdenite surface in 1 ppm polymer solution, it was more difficult for air bubbles to attach to the molybdenite surface due to the weakened hydrophobic interaction with a shorter decay length. Increasing the polymer concentration to 5 ppm effectively inhibited bubble attachment on mineral surface, which was mainly due to the much reduced hydrophobic interaction as well as the additional steric repulsion between the extended polymer chains and bubble surface. The results provide quantitative information on the interaction mechanism between air bubbles and molybdenite mineral surfaces on the nanoscale, with useful implications for the development of effective polymer

  12. Engineering bacterial surface displayed human norovirus capsid proteins: A novel system to explore interaction between norovirus and ligands

    Directory of Open Access Journals (Sweden)

    Mengya eNiu

    2015-12-01

    Full Text Available Human noroviruses (HuNoVs are major contributors to acute nonbacterial gastroenteritis outbreaks. Many aspects of HuNoVs are poorly understood due to both the current inability to culture HuNoVs, and the lack of efficient small animal models. Surrogates for HuNoVs, such as recombinant viral like particles (VLPs expressed in eukaryotic system or P particles expressed in prokaryotic system, have been used for studies in immunology and interaction between the virus and its receptors. However, it is difficult to use VLPs or P particles to collect or isolate potential ligands binding to these recombinant capsid proteins. In this study, a new strategy was used to collect HuNoVs binding ligands through the use of ice nucleation protein (INP to display recombinant capsid proteins of HuNoVs on bacterial surfaces. The viral protein-ligand complex could be easily separated by a low speed centrifugation step. This system was also used to explore interaction between recombinant capsid proteins of HuNoVs and their receptors. In this system, the VP1 capsid encoding gene (ORF2 and the protruding domain (P domain encoding gene (3’ terminal fragment of ORF2 of HuNoVs GI.1 and GII.4 were fused with 5’ terminal fragment of ice nucleation protein encoding gene (inaQn. The results demonstrated that the recombinant VP1 and P domains of HuNoVs were expressed and anchored on the surface of Escherichia coli BL21 cells after the bacteria were transformed with the corresponding plasmids. Both cell surface displayed VP1 and P domains could be recognized by HuNoVs specific antibodies and interact with the viral histo-blood group antigens receptors. In both cases, displayed P domains had better binding abilities than VP1. This new strategy of using displayed HuNoVs capsid proteins on the bacterial surface could be utilized to separate HuNoVs binding components from complex samples, to investigate interaction between the virus and its receptors, as well as to develop an

  13. Interaction of the B cell-specific transcriptional coactivator OCA-B and galectin-1 and a possible role in regulating BCR-mediated B cell proliferation.

    Science.gov (United States)

    Yu, Xin; Siegel, Rachael; Roeder, Robert G

    2006-06-02

    OCA-B is a B cell-specific transcriptional coactivator for OCT factors during the activation of immunoglobulin genes. In addition, OCA-B is crucial for B cell activation and germinal center formation. However, the molecular mechanisms for OCA-B function in these processes are not clear. Our previous studies documented two OCA-B isoforms and suggested a novel mechanism for the function of the myristoylated, membrane-bound form of OCA-B/p35 as a signaling molecule. Here, we report the identification of galectin-1, and related galectins, as a novel OCA-B-interacting protein. The interaction of OCA-B and galectin-1 can be detected both in vivo and in vitro. The galectin-1 binding domain in OCA-B has been localized to the N terminus of OCA-B. In B cells lacking OCA-B expression, increased galectin-1 expression, secretion, and cell surface association are observed. Consistent with these observations, and a reported inhibitory interaction of galectin-1 with CD45, the phosphatase activity of CD45 is reduced modestly, but significantly, in OCA-B-deficient B cells. Finally, galectin-1 is shown to negatively regulate B cell proliferation and tyrosine phosphorylation upon BCR stimulation. Together, these results raise the possibility that OCA-B may regulate BCR signaling through an association with galectin-1.

  14. Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Alan M. [School of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH (United Kingdom); Paxton, Jennifer Z.; Hung, Yi-Pei; Hadley, Martin J.; Bowen, James; Williams, Richard L. [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom); Grover, Liam M., E-mail: l.m.grover@bham.ac.uk [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom)

    2015-03-01

    Calcium phosphate coatings have been applied to the surface of metallic prostheses to mediate hard and soft tissue attachment for more than 40 years. Most coatings are formed of high purity hydroxyapatite, and coating methods are often designed to produce highly crystalline surfaces. It is likely however, that coatings of lower crystallinity can facilitate more rapid tissue attachment since the surface will exhibit a higher specific surface area and will be considerably more reactive than a comparable highly crystalline surface. Here we test this hypothesis by growing a population of MC3T3 osteoblast-like cells on the surface of two types of hip prosthesis with similar composition, but with differing crystallinity. The surfaces with lower crystallinity facilitated more rapid cell attachment and increased proliferation rate, despite having a less heterogeneous surface topography. This work highlights that the influence of the crystallinity of HA at the nano-scale is dominant over macro-scale topography for cell adhesion and growth. Furthermore, crystallinity could be easily adjusted by without compromising coating purity. These findings could facilitate designing novel coated calcium phosphate surfaces that more rapidly bond tissue following implantation. - Highlights: • Crystallinity of HA at the nano-scale was dominant over macro-scale topography. • Lower crystallinity caused rapid cell attachment and proliferation rate. • Crystallinity could be easily adjusted by without compromising coating purity.

  15. Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces

    International Nuclear Information System (INIS)

    Smith, Alan M.; Paxton, Jennifer Z.; Hung, Yi-Pei; Hadley, Martin J.; Bowen, James; Williams, Richard L.; Grover, Liam M.

    2015-01-01

    Calcium phosphate coatings have been applied to the surface of metallic prostheses to mediate hard and soft tissue attachment for more than 40 years. Most coatings are formed of high purity hydroxyapatite, and coating methods are often designed to produce highly crystalline surfaces. It is likely however, that coatings of lower crystallinity can facilitate more rapid tissue attachment since the surface will exhibit a higher specific surface area and will be considerably more reactive than a comparable highly crystalline surface. Here we test this hypothesis by growing a population of MC3T3 osteoblast-like cells on the surface of two types of hip prosthesis with similar composition, but with differing crystallinity. The surfaces with lower crystallinity facilitated more rapid cell attachment and increased proliferation rate, despite having a less heterogeneous surface topography. This work highlights that the influence of the crystallinity of HA at the nano-scale is dominant over macro-scale topography for cell adhesion and growth. Furthermore, crystallinity could be easily adjusted by without compromising coating purity. These findings could facilitate designing novel coated calcium phosphate surfaces that more rapidly bond tissue following implantation. - Highlights: • Crystallinity of HA at the nano-scale was dominant over macro-scale topography. • Lower crystallinity caused rapid cell attachment and proliferation rate. • Crystallinity could be easily adjusted by without compromising coating purity

  16. Molecular Characterization of a Novel Family of Trypanosoma cruzi Surface Membrane Proteins (TcSMP) Involved in Mammalian Host Cell Invasion.

    Science.gov (United States)

    Martins, Nadini Oliveira; Souza, Renata Torres de; Cordero, Esteban Mauricio; Maldonado, Danielle Cortez; Cortez, Cristian; Marini, Marjorie Mendes; Ferreira, Eden Ramalho; Bayer-Santos, Ethel; Almeida, Igor Correia de; Yoshida, Nobuko; Silveira, José Franco da

    2015-11-01

    The surface coat of Trypanosoma cruzi is predominantly composed of glycosylphosphatidylinositol-anchored proteins, which have been extensively characterized. However, very little is known about less abundant surface proteins and their role in host-parasite interactions. Here, we described a novel family of T. cruzi surface membrane proteins (TcSMP), which are conserved among different T. cruzi lineages and have orthologs in other Trypanosoma species. TcSMP genes are densely clustered within the genome, suggesting that they could have originated by tandem gene duplication. Several lines of evidence indicate that TcSMP is a membrane-spanning protein located at the cellular surface and is released into the extracellular milieu. TcSMP exhibited the key elements typical of surface proteins (N-terminal signal peptide or signal anchor) and a C-terminal hydrophobic sequence predicted to be a trans-membrane domain. Immunofluorescence of live parasites showed that anti-TcSMP antibodies clearly labeled the surface of all T. cruzi developmental forms. TcSMP peptides previously found in a membrane-enriched fraction were identified by proteomic analysis in membrane vesicles as well as in soluble forms in the T. cruzi secretome. TcSMP proteins were also located intracellularly likely associated with membrane-bound structures. We demonstrated that TcSMP proteins were capable of inhibiting metacyclic trypomastigote entry into host cells. TcSMP bound to mammalian cells and triggered Ca2+ signaling and lysosome exocytosis, events that are required for parasitophorous vacuole biogenesis. The effects of TcSMP were of lower magnitude compared to gp82, the major adhesion protein of metacyclic trypomastigotes, suggesting that TcSMP may play an auxiliary role in host cell invasion. We hypothesized that the productive interaction of T. cruzi with host cells that effectively results in internalization may depend on diverse adhesion molecules. In the metacyclic forms, the signaling induced by

  17. Nanophotonic force microscopy: characterizing particle-surface interactions using near-field photonics.

    Science.gov (United States)

    Schein, Perry; Kang, Pilgyu; O'Dell, Dakota; Erickson, David

    2015-02-11

    Direct measurements of particle-surface interactions are important for characterizing the stability and behavior of colloidal and nanoparticle suspensions. Current techniques are limited in their ability to measure pico-Newton scale interaction forces on submicrometer particles due to signal detection limits and thermal noise. Here we present a new technique for making measurements in this regime, which we refer to as nanophotonic force microscopy. Using a photonic crystal resonator, we generate a strongly localized region of exponentially decaying, near-field light that allows us to confine small particles close to a surface. From the statistical distribution of the light intensity scattered by the particle we are able to map out the potential well of the trap and directly quantify the repulsive force between the nanoparticle and the surface. As shown in this Letter, our technique is not limited by thermal noise, and therefore, we are able to resolve interaction forces smaller than 1 pN on dielectric particles as small as 100 nm in diameter.

  18. Particle-In-Cell Simulations of the Solar Wind Interaction with Lunar Crustal Magnetic Anomalies: Magnetic Cusp Regions

    Science.gov (United States)

    Poppe, A. R.; Halekas, J. S.; Delory, G. T.; Farrell, W. M.

    2012-01-01

    As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent magnetic fields. These magnetic fields are small-scale, highly non-dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can reflect solar wind protons via a combination of magnetic and electrostatic reflection; however, analyses of surface properties have suggested that protons may still access the lunar surface in the cusp regions of crustal magnetic fields. In this first report from a planned series of studies, we use a 1 1/2-dimensional, electrostatic particle-in-cell code to model the self-consistent interaction between the solar wind, the cusp regions of lunar crustal remanent magnetic fields, and the lunar surface. We describe the self-consistent electrostatic environment within crustal cusp regions and discuss the implications of this work for the role that crustal fields may play regulating space weathering of the lunar surface via proton bombardment.

  19. Interactions between nano-TiO2 and the oral cavity: Impact of nanomaterial surface hydrophilicity/hydrophobicity

    International Nuclear Information System (INIS)

    Teubl, Birgit J.; Schimpel, Christa; Leitinger, Gerd; Bauer, Bettina; Fröhlich, Eleonore; Zimmer, Andreas; Roblegg, Eva

    2015-01-01

    Highlights: • Hydrophilic as well as hydrophobic TiO 2 NPs agglomerated under oral physiological conditions. • Particles penetrated the upper and lower buccal epithelium, independent on the degree of hydrophilicity. • Most of the hydrophobic particles were found in vesicular structures, while hydrophilic particles were freely distributed in the cytoplasm. • Hydrophilic particles had a higher potential to trigger toxic effects (e.g., ROS) than hydrophobic particles. - Abstract: Titanium dioxide (TiO 2 ) nanoparticles are available in a variety of oral applications, such as food additives and cosmetic products. Thus, questions about their potential impact on the oro-gastrointestinal route rise. The oral cavity represents the first portal of entry and is known to rapidly interact with nanoparticles. Surface charge and size contribute actively to the particle–cell interactions, but the influence of surface hydrophilicity/hydrophobicity has never been shown before. This study addresses the biological impact of hydrophilic (NM 103, rutile, 20 nm) and hydrophobic (NM 104, rutile, 20 nm) TiO 2 particles within the buccal mucosa. Particle characterization was addressed with dynamic light scattering and laser diffraction. Despite a high agglomeration tendency, 10% of the particles/agglomerates were present in the nanosized range and penetrated into the mucosa, independent of the surface properties. However, significant differences were observed in intracellular particle localization. NM 104 particles were found freely distributed in the cytoplasm, whereas their hydrophobic counterparts were engulfed in vesicular structures. Although cell viability/membrane integrity was not affected negatively, screening assays demonstrated that NM 104 particles showed a higher potential to decrease the physiological mitochondrial membrane potential than NM 103, resulting in a pronounced generation of reactive oxygen species

  20. Spectral studies of Lanthanide interactions with membrane surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Karukstis, K.K.; Kao, M.Y.; Savin, D.A.; Bittker, R.A.; Kaphengst, K.J.; Emetarom, C.M.; Naito, N.R.; Takamoto, D.Y. [Harvey Mudd College, Claremont, CA (United States)

    1995-03-23

    We have monitored the interactions of the series of trivalent lanthanide cations with the thylakoid membrane surface of spinach chloroplasts using two complementary spectral techniques. Measurements of the fluorescence emission of the extrinsic probe 2-p-toluidinonaphthalene-6-sulfonate (TNS) and the absorbance of the intrinsic chromophore chlorophyll provide two sensitive means of characterizing the dependence of the cation-membrane interaction on the nature of the cation. In these systems, added lanthanide cations adsorb onto the membrane surface to neutralize exposed segments of membrane-embedded protein complexes. The lanthanide-induced charge neutralization increases the proximity of added TNS anion to the membrane surface as evidenced by variations in the TNS fluorescence level and wavelength of maximum emission. Our results reveal a strong dependence of TNS fluorescence parameters on both lanthanide size and total orbital angular momentum L value. Lanthanides with greater charge density (small size and/or low L value) enhance the TNS fluorescence level to a greater extent. A possible origin for the lanthanide-dependent TNS fluorescence levels is suggested in terms of a heterogeneity in the number and type of TNS binding sites. The data are consistent with the proposal that larger lanthanides with smaller enthalpies of hydration induce more significant membrane appression. 59 refs., 9 figs., 2 tabs.

  1. Stem cell responses to plasma surface modified electrospun polyurethane scaffolds.

    Science.gov (United States)

    Zandén, Carl; Hellström Erkenstam, Nina; Padel, Thomas; Wittgenstein, Julia; Liu, Johan; Kuhn, H Georg

    2014-07-01

    The topographical effects from functional materials on stem cell behavior are currently of interest in tissue engineering and regenerative medicine. Here we investigate the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell (hESC) and rat postnatal neural stem cell (NSC) responses. The plasma gases were found to induce three combinations of fiber surface functionalities and roughness textures. On randomly oriented fibers, plasma treatments lead to substantially increased hESC attachment and proliferation as compared to native fibers. Argon plasma was found to induce the most optimal combination of surface functionality and roughness for cell expansion. Contact guided migration of cells and alignment of cell processes were observed on aligned fibers. Neuronal differentiation around 5% was found for all samples and was not significantly affected by the induced variations of surface functional group distribution or individual fiber topography. In this study the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell and rat postnatal neural stem cell (NSC) responses is studied with the goal of clarifying the potential effects of functional materials on stem cell behavior, a topic of substantial interest in tissue engineering and regenerative medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Atom-surface interaction: Zero-point energy formalism

    International Nuclear Information System (INIS)

    Paranjape, V.V.

    1985-01-01

    The interaction energy between an atom and a surface formed by a polar medium is derived with use of a new approach based on the zero-point energy formalism. It is shown that the energy depends on the separation Z between the atom and the surface. With increasing Z, the energy decreases according to 1/Z 3 , while with decreasing Z the energy saturates to a finite value. It is also shown that the energy is affected by the velocity of the atom, but this correction is small. Our result for large Z is consistent with the work of Manson and Ritchie [Phys. Rev. B 29, 1084 (1984)], who follow a more traditional approach to the problem

  3. Characterization of the cell surface properties of drinking water pathogens by microbial adhesion to hydrocarbon and electrophoretic mobility measurements.

    Science.gov (United States)

    Popovici, Jonathan; White, Colin P; Hoelle, Jill; Kinkle, Brian K; Lytle, Darren A

    2014-06-01

    The surface characteristics of microbial cells directly influence their mobility and behavior within aqueous environments. The cell surface hydrophobicity (CSH) and electrophoretic mobility (EPM) of microbial cells impact a number of interactions and processes including aggregation, adhesion to surfaces, and stability of the cells within the aqueous environments. These cell characteristics are unique to the bacterial species and are a reflection of the large diversity of surface structures, proteins, and appendages of microorganisms. CSH and EPM of bacterial cells contribute substantially to the effectiveness of drinking water treatment to remove them, and therefore an investigation of these properties will be useful in predicting their removal through drinking water treatment processes and transport through drinking water distribution systems. EPM and CSH measurements of six microbiological pathogen or surrogate species suspended in phosphate-buffered water are reported in this work. Two strains of Vibrio cholerae were hydrophobic, while three strains of Escherichia coli were hydrophilic. Bacillus cereus was categorized as moderately hydrophobic. The strains of E. coli had the highest (most negative) EPM. Based on the measurements, E. coli species is predicted to be most difficult to remove from water while V. cholerae will be the easiest to remove. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Plasma diagnostics surface analysis and interactions

    CERN Document Server

    Auciello, Orlando

    2013-01-01

    Plasmas and their interaction with materials have become subjects of major interest because of their importance in modern forefront technologies such as microelectronics, fusion energy, and space. Plasmas are used in microelectronics to process semiconductors (etching of patterns for microcircuits, plasma-induced deposition of thin films, etc.); plasmas produce deleterious erosion effects on surfaces of materials used for fusion devices and spaceships exposed to the low earth environment.Diagnostics of plasmas and materials exposed to them are fundamental to the understanding of the physical a

  5. Decellularized matrix from tumorigenic human mesenchymal stem cells promotes neovascularization with galectin-1 dependent endothelial interaction.

    Directory of Open Access Journals (Sweden)

    Jorge S Burns

    Full Text Available BACKGROUND: Acquisition of a blood supply is fundamental for extensive tumor growth. We recently described vascular heterogeneity in tumours derived from cell clones of a human mesenchymal stem cell (hMSC strain (hMSC-TERT20 immortalized by retroviral vector mediated human telomerase (hTERT gene expression. Histological analysis showed that cells of the most vascularized tumorigenic clone, -BD11 had a pericyte-like alpha smooth muscle actin (ASMA+ and CD146+ positive phenotype. Upon serum withdrawal in culture, -BD11 cells formed cord-like structures mimicking capillary morphogenesis. In contrast, cells of the poorly tumorigenic clone, -BC8 did not stain for ASMA, tumours were less vascularized and serum withdrawal in culture led to cell death. By exploring the heterogeneity in hMSC-TERT20 clones we aimed to understand molecular mechanisms by which mesenchymal stem cells may promote neovascularization. METHODOLOGY/PRINCIPAL FINDINGS: Quantitative qRT-PCR analysis revealed similar mRNA levels for genes encoding the angiogenic cytokines VEGF and Angiopoietin-1 in both clones. However, clone-BD11 produced a denser extracellular matrix that supported stable ex vivo capillary morphogenesis of human endothelial cells and promoted in vivo neovascularization. Proteomic characterization of the -BD11 decellularized matrix identified 50 extracellular angiogenic proteins, including galectin-1. siRNA knock down of galectin-1 expression abrogated the ex vivo interaction between decellularized -BD11 matrix and endothelial cells. More stable shRNA knock down of galectin-1 expression did not prevent -BD11 tumorigenesis, but greatly reduced endothelial migration into -BD11 cell xenografts. CONCLUSIONS: Decellularized hMSC matrix had significant angiogenic potential with at least 50 angiogenic cell surface and extracellular proteins, implicated in attracting endothelial cells, their adhesion and activation to form tubular structures. hMSC -BD11 surface galectin-1

  6. Decellularized Matrix from Tumorigenic Human Mesenchymal Stem Cells Promotes Neovascularization with Galectin-1 Dependent Endothelial Interaction

    Science.gov (United States)

    Burns, Jorge S.; Kristiansen, Malthe; Kristensen, Lars P.; Larsen, Kenneth H.; Nielsen, Maria O.; Christiansen, Helle; Nehlin, Jan; Andersen, Jens S.; Kassem, Moustapha

    2011-01-01

    Background Acquisition of a blood supply is fundamental for extensive tumor growth. We recently described vascular heterogeneity in tumours derived from cell clones of a human mesenchymal stem cell (hMSC) strain (hMSC-TERT20) immortalized by retroviral vector mediated human telomerase (hTERT) gene expression. Histological analysis showed that cells of the most vascularized tumorigenic clone, -BD11 had a pericyte-like alpha smooth muscle actin (ASMA+) and CD146+ positive phenotype. Upon serum withdrawal in culture, -BD11 cells formed cord-like structures mimicking capillary morphogenesis. In contrast, cells of the poorly tumorigenic clone, -BC8 did not stain for ASMA, tumours were less vascularized and serum withdrawal in culture led to cell death. By exploring the heterogeneity in hMSC-TERT20 clones we aimed to understand molecular mechanisms by which mesenchymal stem cells may promote neovascularization. Methodology/Principal Findings Quantitative qRT-PCR analysis revealed similar mRNA levels for genes encoding the angiogenic cytokines VEGF and Angiopoietin-1 in both clones. However, clone-BD11 produced a denser extracellular matrix that supported stable ex vivo capillary morphogenesis of human endothelial cells and promoted in vivo neovascularization. Proteomic characterization of the -BD11 decellularized matrix identified 50 extracellular angiogenic proteins, including galectin-1. siRNA knock down of galectin-1 expression abrogated the ex vivo interaction between decellularized -BD11 matrix and endothelial cells. More stable shRNA knock down of galectin-1 expression did not prevent -BD11 tumorigenesis, but greatly reduced endothelial migration into -BD11 cell xenografts. Conclusions Decellularized hMSC matrix had significant angiogenic potential with at least 50 angiogenic cell surface and extracellular proteins, implicated in attracting endothelial cells, their adhesion and activation to form tubular structures. hMSC -BD11 surface galectin-1 expression was

  7. Interactions of bluff-body obstacles with turbulent airflows affecting evaporative fluxes from porous surfaces

    Science.gov (United States)

    Haghighi, Erfan; Or, Dani

    2015-11-01

    Bluff-body obstacles interacting with turbulent airflows are common in many natural and engineering applications (from desert pavement and shrubs over natural surfaces to cylindrical elements in compact heat exchangers). Even with obstacles of simple geometry, their interactions within turbulent airflows result in a complex and unsteady flow field that affects surface drag partitioning and transport of scalars from adjacent evaporating surfaces. Observations of spatio-temporal thermal patterns on evaporating porous surfaces adjacent to bluff-body obstacles depict well-defined and persistent zonation of evaporation rates that were used to construct a simple mechanistic model for surface-turbulence interactions. Results from evaporative drying of sand surfaces with isolated cylindrical elements (bluff bodies) subjected to constant turbulent airflows were in good agreement with model predictions for localized exchange rates. Experimental and theoretical results show persistent enhancement of evaporative fluxes from bluff-rough surfaces relative to smooth flat surfaces under similar conditions. The enhancement is attributed to formation of vortices that induce a thinner boundary layer over part of the interacting surface footprint. For a practical range of air velocities (0.5-4.0 m/s), low-aspect ratio cylindrical bluff elements placed on evaporating sand surfaces enhanced evaporative mass losses (relative to a flat surface) by up to 300% for high density of elements and high wind velocity, similar to observations reported in the literature. Concepts from drag partitioning were used to generalize the model and upscale predictions to evaporation from surfaces with multiple obstacles for potential applications to natural bluff-rough surfaces.

  8. EDITORIAL: Plasma Surface Interactions for Fusion

    Science.gov (United States)

    2006-05-01

    Because plasma-boundary physics encompasses some of the most important unresolved issues for both the International Thermonuclear Experimental Reactor (ITER) project and future fusion power reactors, there is a strong interest in the fusion community for better understanding and characterization of plasma wall interactions. Chemical and physical sputtering cause the erosion of the limiters/divertor plates and vacuum vessel walls (made of C, Be and W, for example) and degrade fusion performance by diluting the fusion fuel and excessively cooling the core, while carbon redeposition could produce long-term in-vessel tritium retention, degrading the superior thermo-mechanical properties of the carbon materials. Mixed plasma-facing materials are proposed, requiring optimization for different power and particle flux characteristics. Knowledge of material properties as well as characteristics of the plasma material interaction are prerequisites for such optimizations. Computational power will soon reach hundreds of teraflops, so that theoretical and plasma science expertise can be matched with new experimental capabilities in order to mount a strong response to these challenges. To begin to address such questions, a Workshop on New Directions for Advanced Computer Simulations and Experiments in Fusion-Related Plasma Surface Interactions for Fusion (PSIF) was held at the Oak Ridge National Laboratory from 21 to 23 March, 2005. The purpose of the workshop was to bring together researchers in fusion related plasma wall interactions in order to address these topics and to identify the most needed and promising directions for study, to exchange opinions on the present depth of knowledge of surface properties for the main fusion-related materials, e.g., C, Be and W, especially for sputtering, reflection, and deuterium (tritium) retention properties. The goal was to suggest the most important next steps needed for such basic computational and experimental work to be facilitated

  9. Functional Analysis of Lactobacillus rhamnosus GG Pili in Relation to Adhesion and Immunomodulatory Interactions with Intestinal Epithelial Cells

    Science.gov (United States)

    Claes, Ingmar; Tytgat, Hanne L. P.; Verhoeven, Tine L. A.; Marien, Eyra; von Ossowski, Ingemar; Reunanen, Justus; Palva, Airi; de Vos, Willem M.; De Keersmaecker, Sigrid C. J.; Vanderleyden, Jos

    2012-01-01

    Lactobacillus rhamnosus GG, a probiotic with good survival capacity in the human gut, has well-documented adhesion properties and health effects. Recently, spaCBA-encoded pili that bind to human intestinal mucus were identified on its cell surface. Here, we report on the phenotypic analysis of a spaCBA pilus knockout mutant in comparison with the wild type and other adhesin mutants. The SpaCBA pilus of L. rhamnosus GG showed to be key for efficient adherence to the Caco-2 intestinal epithelial cell (IEC) line and biofilm formation. Moreover, the spaCBA mutant induces an elevated level of interleukin-8 (IL-8) mRNA in Caco-2 cells compared to the wild type, possibly involving an interaction of lipoteichoic acid with Toll-like receptor 2. In contrast, an L. rhamnosus GG mutant without exopolysaccharides but with an increased exposure of pili leads to the reduced expression of IL-8. Using Transwells to partition bacteria from Caco-2 cells, IL-8 induction is blocked completely regardless of whether wild-type or mutant L. rhamnosus GG cells are used. Taken together, our data suggest that L. rhamnosus GG SpaCBA pili, while promoting strong adhesive interactions with IECs, have a functional role in balancing IL-8 mRNA expression induced by surface molecules such as lipoteichoic acid. PMID:22020518

  10. Carrier population control and surface passivation in solar cells

    KAUST Repository

    Cuevas, Andres

    2018-05-02

    Controlling the concentration of charge carriers near the surface is essential for solar cells. It permits to form regions with selective conductivity for either electrons or holes and it also helps to reduce the rate at which they recombine. Chemical passivation of the surfaces is equally important, and it can be combined with population control to implement carrier-selective, passivating contacts for solar cells. This paper discusses different approaches to suppress surface recombination and to manipulate the concentration of carriers by means of doping, work function and charge. It also describes some of the many surface-passivating contacts that are being developed for silicon solar cells, restricted to experiments performed by the authors.

  11. Mesoporous silica particles modified with graphitic carbon: interaction with human red blood cells and plasma proteins

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Diego Stefani Teodoro; Franqui, Lidiane Silva; Bettini, Jefferson; Strauss, Mathias, E-mail: diego.martinez@lnnano.cnpem.br [Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP (Brazil); Damasceno, Joao Paulo Vita; Mazali, Italo Odone [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2016-07-01

    Full text: In this work the interaction of the mesoporous silica particles (SBA-15, ∼700 nm) modified with graphitic carbon (SBA-15/C) on human red blood cells (hemolysis) and plasma proteins (protein corona formation) is studied. XPS and CHN analysis showed that the carbon content on the SBA-15/C samples varied from 2 to 10% and was tuned by the functionalization step. The formed carbon structures where associated to graphitic nanodomains coating the pores surface as verified by Raman spectroscopy and {sup 13}C NMR. Advanced TEM/EELS analysis showed that the carbon structures are distributed along the SBA-15 mesopores. SAXS and textural analyses were used to confirm that the porous structure of the silica support is kept after the modification procedure and to calculate the number of graphitic carbon stacked layers coating the mesopores. After incubation of SBA-15 with human red blood cells (RBCs), it was observed a dose-dependent hemolytic effect, probably, due to binding of the material silanol-rich surface to the phosphatidylcholine molecules from the RBC membrane. The graphitic carbon modifications have mitigated this effect, indicating that the graphitic carbon coating protected the silanol groups of the particle surface hindering the hemolysis. Considering the protein corona formation, selective biomolecular interaction of proteins was observed for the different materials using gel electrophoresis (SDS-PAGE) analysis. Besides, graphitic carbon modification decreased the amount of proteins on the corona. Together, the in vitro hemolysis and protein corona assays are promising biological models to understand the influence of silica surface functionalization on their bionano-interactions. Finally, our work contributes to the development of fundamental research on such nanomaterials chemistry in the emerging field of nanobioscience and nanotoxicology. (author)

  12. Nanolayer surface passivation schemes for silicon solar cells

    NARCIS (Netherlands)

    Dingemans, G.

    2011-01-01

    This thesis is concerned with nanolayer surface passivation schemes and corresponding deposition processes, for envisaged applications in crystalline silicon solar cells. Surface passivation, i.e. the reduction of electronic recombination processes at semiconductor surfaces, is essential for

  13. Functional Elements on SIRPα IgV domain Mediate Cell Surface Binding to CD47

    Science.gov (United States)

    Liu, Yuan; Tong, Qiao; Zhou, Yubin; Lee, Hsiau-Wei; Yang, Jenny J.; Bühring, Hans-Jörg; Chen, Yi-Tien; Ha, Binh; Chen, Celia X-J.; Zen, Ke

    2007-01-01

    Summary SIRPα and SIRPβ1, the two major isoforms of the signal regulatory protein (SIRP) family, are co-expressed in human leukocytes but mediate distinct extracellular binding interactions and divergent cell signaling responses. Previous studies have demonstrated that binding of SIRPα with CD47, another important cell surface molecule, through the extracellular IgV domain regulates important leukocyte functions including macrophage recognition, leukocyte adhesion and transmigration. Although SIRPβ1 shares highly homologous extracellular IgV structure with SIRPα, it does not bind to CD47. In this study, we defined key amino acid residues exclusively expressing in the IgV domain of SIRPα, but not SIRPβ1, which determine the extracellular binding interaction of SIRPα to CD47. These key residues include Gln67, a small hydrophobic amino acid (Ala or Val) at the 57th position and Met102. We found that Gln67 and Ala/Val57 are critical. Mutation of either of these residues abates SIRPα directly binding to CD47. Functional cell adhesion and leukocyte transmigration assays further demonstrated central roles of Gln67 and Ala/Val57 in SIRPα extracellular binding mediated cell interactions and cell migration. Another SIRPα-specific residue, Met102, appears to assist SIRPα IgV binding through Gln67 and Ala/Val57. An essential role of these amino acids in SIRPα binding to CD47 was further confirmed by introducing these residues into the SIRPβ1 IgV domain, which dramatically converts SIRPβ1 into a CD47-binding molecule. Our results thus revealed the molecular basis by which SIRPα selectively binds to CD47 and shed new light into the structural mechanisms of SIRP isoform mediated distinctive extracellular interactions and cellular responses. PMID:17070842

  14. Functional elements on SIRPalpha IgV domain mediate cell surface binding to CD47.

    Science.gov (United States)

    Liu, Yuan; Tong, Qiao; Zhou, Yubin; Lee, Hsiau-Wei; Yang, Jenny J; Bühring, Hans-Jörg; Chen, Yi-Tien; Ha, Binh; Chen, Celia X-J; Yang, Yang; Zen, Ke

    2007-01-19

    SIRPalpha and SIRPbeta1, the two major isoforms of the signal regulatory protein (SIRP) family, are co-expressed in human leukocytes but mediate distinct extracellular binding interactions and divergent cell signaling responses. Previous studies have demonstrated that binding of SIRPalpha with CD47, another important cell surface molecule, through the extracellular IgV domain regulates important leukocyte functions including macrophage recognition, leukocyte adhesion and transmigration. Although SIRPbeta1 shares highly homologous extracellular IgV structure with SIRPalpha, it does not bind to CD47. Here, we defined key amino acid residues exclusively expressing in the IgV domain of SIRPalpha, but not SIRPbeta1, which determine the extracellular binding interaction of SIRPalpha to CD47. These key residues include Gln67, a small hydrophobic amino acid (Ala or Val) at the 57th position and Met102. We found that Gln67 and Ala/Val57 are critical. Mutation of either of these residues abates SIRPalpha directly binding to CD47. Functional cell adhesion and leukocyte transmigration assays further demonstrated central roles of Gln67 and Ala/Val57 in SIRPalpha extracellular binding mediated cell interactions and cell migration. Another SIRPalpha-specific residue, Met102, appears to assist SIRPalpha IgV binding through Gln67 and Ala/Val57. An essential role of these amino acid residues in SIRPalpha binding to CD47 was further confirmed by introducing these residues into the SIRPbeta1 IgV domain, which dramatically converts SIRPbeta1 into a CD47-binding molecule. Our results thus revealed the molecular basis by which SIRPalpha binds to CD47 and shed new light into the structural mechanisms of SIRP isoform mediated distinctive extracellular interactions and cellular responses.

  15. Use of scanning electron microscopy to monitor nanofibre/cell interaction in digestive epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Millaku, Agron, E-mail: agron.mi@hotmail.com [Limnos-Company for Applied Ecology Ltd, Podlimbarskega 31, 1000 Ljubljana (Slovenia); Drobne, Damjana [University of Ljubljana, Biotechnical Faculty, Department of Biology, Večna pot 111, 1000 Ljubljana (Slovenia); Centre of Excellence, Advanced Materials and Technologies for the Future (CO NAMASTE), Jamova cesta 39, 1000 Ljubljana (Slovenia); Centre of Excellence, Nanoscience and Nanotechnology (Nanocentre), Jamova cesta 39, 1000 Ljubljana (Slovenia); Torkar, Matjaz [Institute of Metals and Technology IMT, Lepi pot 11, 1000 Ljubljana (Slovenia); Jožef Stefan Institute, Condensed Matter Physics Department, Jamova cesta 39, 1000 Ljubljana (Slovenia); Novak, Sara [University of Ljubljana, Biotechnical Faculty, Department of Biology, Večna pot 111, 1000 Ljubljana (Slovenia); Remškar, Maja [Jožef Stefan Institute, Condensed Matter Physics Department, Jamova cesta 39, 1000 Ljubljana (Slovenia); Pipan-Tkalec, Živa [University of Ljubljana, Biotechnical Faculty, Department of Biology, Večna pot 111, 1000 Ljubljana (Slovenia)

    2013-09-15

    Graphical abstract: Scanning electron microscopy is particularly well suited to the observation of nanofibre/cell interaction in the endothelial cells lining the hepatopancreas. (a) Tungsten oxide nanofibres, (b) test organism Porcellio scaber and schematic appearance of digestive tubes, (c) digestive tube (hepatopancreas) prepared for SEM investigation, (d) digestive gland cells (C) with nanofibres (NF) embedded in the cell membrane and (e) nanofibres inserted deeply in the cells and damaged nanofibres due to peristalsis. -- Highlights: • Tungsten oxide nanofibres react physically with digestive gland epithelial cells in Porcellio scaber. • Physical peristaltic forces of lead to insertion of nanofibres into the cells. • No toxic responses as measured by conventional toxicity biomarkers were detected. • Physical interactions were observed in a majority of the investigated animals. -- Abstract: We provide data obtained by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) on the interaction of ingested tungsten nanofibers with epithelial cells of the digestive tubes of a test organism Porcellio scaber. Conventional toxicity endpoints including feeding behaviour, weight loss and mortality were also measured in each investigated animal. No toxicity was detected in any of exposed animals after 14 days of feeding on tungsten nanofiber dosed food, but when nanofibers enter the digestive system they can react with epithelial cells of the digestive tubes, becoming physically inserted into the cells. In this way, nanofibers can injure the epithelial cells of digestive gland tubes when they are ingested with food. Our SEM data suggest that peristaltic forces may have an important role, not predicted by in vitro experiments, in the interactions of nanomaterials with digestive intestinal cells.

  16. Use of scanning electron microscopy to monitor nanofibre/cell interaction in digestive epithelial cells

    International Nuclear Information System (INIS)

    Millaku, Agron; Drobne, Damjana; Torkar, Matjaz; Novak, Sara; Remškar, Maja; Pipan-Tkalec, Živa

    2013-01-01

    Graphical abstract: Scanning electron microscopy is particularly well suited to the observation of nanofibre/cell interaction in the endothelial cells lining the hepatopancreas. (a) Tungsten oxide nanofibres, (b) test organism Porcellio scaber and schematic appearance of digestive tubes, (c) digestive tube (hepatopancreas) prepared for SEM investigation, (d) digestive gland cells (C) with nanofibres (NF) embedded in the cell membrane and (e) nanofibres inserted deeply in the cells and damaged nanofibres due to peristalsis. -- Highlights: • Tungsten oxide nanofibres react physically with digestive gland epithelial cells in Porcellio scaber. • Physical peristaltic forces of lead to insertion of nanofibres into the cells. • No toxic responses as measured by conventional toxicity biomarkers were detected. • Physical interactions were observed in a majority of the investigated animals. -- Abstract: We provide data obtained by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) on the interaction of ingested tungsten nanofibers with epithelial cells of the digestive tubes of a test organism Porcellio scaber. Conventional toxicity endpoints including feeding behaviour, weight loss and mortality were also measured in each investigated animal. No toxicity was detected in any of exposed animals after 14 days of feeding on tungsten nanofiber dosed food, but when nanofibers enter the digestive system they can react with epithelial cells of the digestive tubes, becoming physically inserted into the cells. In this way, nanofibers can injure the epithelial cells of digestive gland tubes when they are ingested with food. Our SEM data suggest that peristaltic forces may have an important role, not predicted by in vitro experiments, in the interactions of nanomaterials with digestive intestinal cells

  17. Hydrodynamic attraction of swimming microorganisms by surfaces

    OpenAIRE

    Berke, Allison P.; Turner, Linda; Berg, Howard C.; Lauga, Eric

    2008-01-01

    Cells swimming in confined environments are attracted by surfaces. We measure the steady-state distribution of smooth-swimming bacteria (Escherichia coli) between two glass plates. In agreement with earlier studies, we find a strong increase of the cell concentration at the boundaries. We demonstrate theoretically that hydrodynamic interactions of the swimming cells with solid surfaces lead to their re-orientation in the direction parallel to the surfaces, as well as their attraction by the c...

  18. Radioimmunoassay to quantitatively measure cell surface immunoglobulins

    International Nuclear Information System (INIS)

    Krishman, E.C.; Jewell, W.R.

    1975-01-01

    A radioimmunoassay techniques developed to quantitatively measure the presence of immunoglobulins on the surface of cells, is described. The amount of immunoglobulins found on different tumor cells varied from 200 to 1140 ng/10 6 cells. Determination of immunoglobulins on the peripheral lymphocytes obtained from different cancer patients varied between 340 to 1040 ng/10 6 cells. Cultured tumor cells, on the other hand, were found to contain negligible quantities of human IgG [pt

  19. Lactobacillus reuteri Surface Mucus Adhesins Upregulate Inflammatory Responses Through Interactions With Innate C-Type Lectin Receptors.

    Science.gov (United States)

    Bene, Krisztián P; Kavanaugh, Devon W; Leclaire, Charlotte; Gunning, Allan P; MacKenzie, Donald A; Wittmann, Alexandra; Young, Ian D; Kawasaki, Norihito; Rajnavolgyi, Eva; Juge, Nathalie

    2017-01-01

    The vertebrate gut symbiont Lactobacillus reuteri exhibits strain-specific adhesion and health-promoting properties. Here, we investigated the role of the mucus adhesins, CmbA and MUB, upon interaction of L. reuteri ATCC PTA 6475 and ATCC 53608 strains with human monocyte-derived dendritic cells (moDCs). We showed that mucus adhesins increased the capacity of L. reuteri strains to interact with moDCs and promoted phagocytosis. Our data also indicated that mucus adhesins mediate anti- and pro-inflammatory effects by the induction of interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), IL-1β, IL-6, and IL-12 cytokines. L. reuteri ATCC PTA 6475 and ATCC 53608 were exclusively able to induce moDC-mediated Th1 and Th17 immune responses. We further showed that purified MUB activates moDCs and induces Th1 polarized immune responses associated with increased IFNγ production. MUB appeared to mediate these effects via binding to C-type lectin receptors (CLRs), as shown using cell reporter assays. Blocking moDCs with antibodies against DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) or Dectin-2 did not affect the uptake of the MUB-expressing strain, but reduced the production of TNF-α and IL-6 by moDCs significantly, in line with the Th1 polarizing capacity of moDCs. The direct interaction between MUB and CLRs was further confirmed by atomic force spectroscopy. Taken together these data suggest that mucus adhesins expressed at the cell surface of L. reuteri strains may exert immunoregulatory effects in the gut through modulating the Th1-promoting capacity of DCs upon interaction with C-type lectins.

  20. Electron-phonon interaction on an Al(001) surface

    International Nuclear Information System (INIS)

    Sklyadneva, I Yu; Chulkov, E V; Echenique, P M

    2008-01-01

    We report an ab initio study of the electron-phonon (e-ph) interaction and its contribution to the lifetime broadening of excited hole (electron) surface states on Al(001). The calculations based on density-functional theory were carried out using a linear response approach in the plane-wave pseudopotential representation. The obtained results show that both the electron-phonon coupling and the linewidth experience a weak variation with the energy and momentum position of a hole (electron) surface state in the energy band. An analysis of different contributions to the e-ph coupling reveals that bulk phonon modes turn out to be more involved in the scattering processes of excited electrons and holes than surface phonon modes. It is also shown that the role of the e-ph coupling in the broadening of the Rayleigh surface phonon mode is insignificant compared to anharmonic effects

  1. Polymer microfilters with nanostructured surfaces for the culture of circulating cancer cells

    International Nuclear Information System (INIS)

    Makarova, Olga V.; Adams, Daniel L.; Divan, Ralu; Rosenmann, Daniel; Zhu, Peixuan; Li, Shuhong; Amstutz, Platte; Tang, Cha-Mei

    2016-01-01

    There is a critical need to improve the accuracy of drug screening and testing through the development of in vitro culture systems that more effectively mimic the in vivo environment. Surface topographical features on the nanoscale level, in short nanotopography, effect the cell growth patterns, and hence affect cell function in culture. We report the preliminary results on the fabrication, and subsequent cellular growth, of nanoscale surface topography on polymer microfilters using cell lines as a precursor to circulating tumor cells (CTCs). To create various nanoscale features on the microfilter surface, we used reactive ion etching (RIE) with and without an etching mask. An anodized aluminum oxide (AAO) membrane fabricated directly on the polymer surface served as an etching mask. Polymer filters with a variety of modified surfaces were used to compare the effects on the culture of cancer cell lines in blank culture wells, with untreated microfilters or with RIE-treated microfilters. We then report the differences of cell shape, phenotype and growth patterns of bladder and glioblastoma cancer cell lines after isolation on the various types of material modifications. Our data suggest that RIE modified polymer filters can isolate model cell lines while retaining ell viability, and that the RIE filter modification allows T24 monolayering cells to proliferate as a structured cluster. - Highlights: • Surface topographical effects the growth patterns and cell function of cancer cells • Nanoscale surface topography on polymer filters for circulating tumor cell culture • Membrane fabricated directly on polymer surfaces utilized for polymer etching • Nanotopography alters cell shape, phenotype and growth patterns of cancer cells • Nanoscale surface topography dictates monolayering or 3D structured cell culture

  2. Polymer microfilters with nanostructured surfaces for the culture of circulating cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Makarova, Olga V. [Creatv MicroTech, Inc., 2242 West Harrison St., Chicago 60612, IL (United States); Adams, Daniel L., E-mail: dan@creatvmicrotech.com [Creatv MicroTech, Inc., 1 Deer Park Drive, Monmouth Junction, NJ 08852 (United States); Divan, Ralu; Rosenmann, Daniel [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Ave., Argonne 60439, IL (United States); Zhu, Peixuan; Li, Shuhong; Amstutz, Platte; Tang, Cha-Mei [Creatv MicroTech, Inc., 11609 Lake Potomac Drive, Potomac 20854, MD (United States)

    2016-09-01

    There is a critical need to improve the accuracy of drug screening and testing through the development of in vitro culture systems that more effectively mimic the in vivo environment. Surface topographical features on the nanoscale level, in short nanotopography, effect the cell growth patterns, and hence affect cell function in culture. We report the preliminary results on the fabrication, and subsequent cellular growth, of nanoscale surface topography on polymer microfilters using cell lines as a precursor to circulating tumor cells (CTCs). To create various nanoscale features on the microfilter surface, we used reactive ion etching (RIE) with and without an etching mask. An anodized aluminum oxide (AAO) membrane fabricated directly on the polymer surface served as an etching mask. Polymer filters with a variety of modified surfaces were used to compare the effects on the culture of cancer cell lines in blank culture wells, with untreated microfilters or with RIE-treated microfilters. We then report the differences of cell shape, phenotype and growth patterns of bladder and glioblastoma cancer cell lines after isolation on the various types of material modifications. Our data suggest that RIE modified polymer filters can isolate model cell lines while retaining ell viability, and that the RIE filter modification allows T24 monolayering cells to proliferate as a structured cluster. - Highlights: • Surface topographical effects the growth patterns and cell function of cancer cells • Nanoscale surface topography on polymer filters for circulating tumor cell culture • Membrane fabricated directly on polymer surfaces utilized for polymer etching • Nanotopography alters cell shape, phenotype and growth patterns of cancer cells • Nanoscale surface topography dictates monolayering or 3D structured cell culture.

  3. Isthmin is a novel vascular permeability inducer that functions through cell-surface GRP78-mediated Src activation.

    Science.gov (United States)

    Venugopal, Shruthi; Chen, Mo; Liao, Wupeng; Er, Shi Yin; Wong, Wai-Shiu Fred; Ge, Ruowen

    2015-07-01

    Isthmin (ISM) is a recently identified 60 kDa secreted angiogenesis inhibitor. Two cell-surface receptors for ISM have been defined, the high-affinity glucose-regulated protein 78 kDa (GRP78) and the low-affinity αvβ5 integrin. As αvβ5 integrin plays an important role in pulmonary vascular permeability (VP) and ISM is highly expressed in mouse lung, we sought to clarify the role of ISM in VP. Recombinant ISM (rISM) dose-dependently enhances endothelial monolayer permeability in vitro and local dermal VP when administered intradermally in mice. Systemic rISM administration through intravenous injection leads to profound lung vascular hyperpermeability but not in other organs. Mechanistic investigations using molecular, biochemical approaches and specific chemical inhibitors revealed that ISM-GRP78 interaction triggers a direct interaction between GRP78 and Src, leading to Src activation and subsequent phosphorylation of adherens junction proteins and loss of junctional proteins from inter-endothelial junctions, resulting in enhanced VP. Dynamic studies of Src activation, VP and apoptosis revealed that ISM induces VP directly via Src activation while apoptosis contributes indirectly only after prolonged treatment. Furthermore, ISM is significantly up-regulated in lipopolysaccharide (LPS)-treated mouse lung. Blocking cell-surface GRP78 by systemic infusion of anti-GRP78 antibody significantly attenuates pulmonary vascular hyperpermeability in LPS-induced acute lung injury (ALI) in mice. ISM is a novel VP inducer that functions through cell-surface GRP78-mediated Src activation as well as induction of apoptosis. It induces a direct GRP78-Src interaction, leading to cytoplasmic Src activation. ISM contributes to pulmonary vascular hyperpermeability of LPS-induced ALI in mice. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  4. Surface-state mediated three-adsorbate interaction: exact and numerical results and simple asymptotic expression

    International Nuclear Information System (INIS)

    Hyldgaard, Per; Einstein, T.L.

    2003-01-01

    The interaction energy of three adsorbates on a surface consists of the sum of the three-pair interactions plus a trio contribution produced primarily by interference of electrons which traverse the entire perimeter, d 123 , of the three-adsorbate cluster. Here, we investigate this three-adatom interaction when mediated by the isotropic Shockley surface-state band found on noble-metal (1 1 1) surfaces, extending work on pair interactions. Our experimentally testable result depends on the s-wave phase-shift, characterizing the standing-wave patterns seen in scanning-tunneling microscopy (STM) images. Compared with the adsorbate-pair interactions, and in contrast to bulk-mediated interactions, the trio contribution exhibits a slightly weaker amplitude and a slightly faster asymptotic envelope decay, d 123 -5/2 . It also has a different but well-defined oscillation period dependent on d 123 and little dependence on the shape of the cluster. We finally compare the asymptotic description with exact model calculations assuming short-range interactions, which are viable even in the non-asymptotic range (when not outweighed by bulk-mediated interactions)

  5. Genetic analysis of the SARS-coronavirus spike glycoprotein functional domains involved in cell-surface expression and cell-to-cell fusion

    International Nuclear Information System (INIS)

    Petit, Chad M.; Melancon, Jeffrey M.; Chouljenko, Vladimir N.; Colgrove, Robin; Farzan, Michael; Knipe, David M.; Kousoulas, K.G.

    2005-01-01

    The SARS-coronavirus (SARS-CoV) is the etiological agent of severe acute respiratory syndrome (SARS). The SARS-CoV spike (S) glycoprotein mediates membrane fusion events during virus entry and virus-induced cell-to-cell fusion. To delineate functional domains of the SARS-CoV S glycoprotein, single point mutations, cluster-to-lysine and cluster-to-alanine mutations, as well as carboxyl-terminal truncations were investigated in transient expression experiments. Mutagenesis of either the coiled-coil domain of the S glycoprotein amino terminal heptad repeat, the predicted fusion peptide, or an adjacent but distinct region, severely compromised S-mediated cell-to-cell fusion, while intracellular transport and cell-surface expression were not adversely affected. Surprisingly, a carboxyl-terminal truncation of 17 amino acids substantially increased S glycoprotein-mediated cell-to-cell fusion suggesting that the terminal 17 amino acids regulated the S fusogenic properties. In contrast, truncation of 26 or 39 amino acids eliminating either one or both of the two endodomain cysteine-rich motifs, respectively, inhibited cell fusion in comparison to the wild-type S. The 17 and 26 amino-acid deletions did not adversely affect S cell-surface expression, while the 39 amino-acid truncation inhibited S cell-surface expression suggesting that the membrane proximal cysteine-rich motif plays an essential role in S cell-surface expression. Mutagenesis of the acidic amino-acid cluster in the carboxyl terminus of the S glycoprotein as well as modification of a predicted phosphorylation site within the acidic cluster revealed that this amino-acid motif may play a functional role in the retention of S at cell surfaces. This genetic analysis reveals that the SARS-CoV S glycoprotein contains extracellular domains that regulate cell fusion as well as distinct endodomains that function in intracellular transport, cell-surface expression, and cell fusion

  6. Human immunodeficiencies related to APC/T cell interaction

    Directory of Open Access Journals (Sweden)

    Marinos eKallikourdis

    2015-08-01

    Full Text Available The primary event for initiating adaptive immune responses is the encounter between T lymphocytes and antigen presenting cells (APC in the T cell area of secondary lymphoid organs and the formation of highly organized inter-cellular junctions referred to as the immune synapses. In vivo live-cell imaging of APC-T cell interactions combined to functional studies unveiled that T cell fate is dictated, in large part, by the stability of the initial contact. Immune cell interaction is equally important during delivery of T cell help to B cells and for the killing of target cells by cytotoxic T cells and NK cells. The critical role of contact dynamics and synapse stability on the immune response is well illustrated by human immune deficiencies in which disease pathogenesis is linked to altered adhesion or defective cross-talk between the synaptic partners. Here we will discuss in details the mechanisms of defective APC-T cell communications in Wiskott-Aldrich syndrome (WAS and in warts, hypogammaglobulinemia, infections, myelokathexis syndrome (WHIM. In addition, we will summarize the evidences pointing to a compromised conjugate formation in WIP deficiency, DOCK8 deficiency and X-linked lymphoproliferative syndrome.

  7. Microarray of neuroblastoma cells on the selectively functionalized nanocrystalline diamond thin film surface

    International Nuclear Information System (INIS)

    Park, Young-Sang; Son, Hyeong-Guk; Kim, Dae-Hoon; Oh, Hong-Gi; Lee, Da-Som; Kim, Min-Hye; Lim, Ki-Moo; Song, Kwang-Soup

    2016-01-01

    Graphical abstract: - Highlights: • The nanocrystalline diamond (NCD) surface is functionalized with F or O. • The cell adhesion and growth are evaluated on the functionalized NCD surface. • The cell adhesion and growth depend on the wettability of the surface. • Cell patterning was achieved by using of hydrophilic and hydrophobic surfaces. • Neuroblastoma cells were arrayed on the micro-patterned NCD surface. - Abstract: Nanocrystalline diamond (NCD) film surfaces were modified with fluorine or oxygen by plasma treatment in an O_2 or C_3F_8 gas environment in order to induce wettability. The oxygenated-NCD (O-NCD) film surface was hydrophilic and the fluorinated-NCD (F-NCD) surface was hydrophobic. The efficiency of early cell adhesion, which is dependent on the wettability of the cell culture plate and necessary for the growth and proliferation of cells, was 89.62 ± 3.92% on the O-NCD film and 7.78 ± 0.77% on the F-NCD film surface after 3 h of cell culture. The wettability of the NCD film surface was artificially modified using a metal mask and plasma treatment to fabricate a micro-pattern. Four types of micro-patterns were fabricated (line, circle, mesh, and word) on the NCD film surface. We precisely arrayed the neuroblastoma cells on the micro-patterned NCD film surfaces by controlling the surface wettability and cell seeding density. The neuroblastoma cells adhered and proliferated along the O-NCD film surface.

  8. Microarray of neuroblastoma cells on the selectively functionalized nanocrystalline diamond thin film surface

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young-Sang; Son, Hyeong-Guk; Kim, Dae-Hoon; Oh, Hong-Gi; Lee, Da-Som; Kim, Min-Hye; Lim, Ki-Moo; Song, Kwang-Soup, E-mail: kssong10@kumoh.ac.kr

    2016-01-15

    Graphical abstract: - Highlights: • The nanocrystalline diamond (NCD) surface is functionalized with F or O. • The cell adhesion and growth are evaluated on the functionalized NCD surface. • The cell adhesion and growth depend on the wettability of the surface. • Cell patterning was achieved by using of hydrophilic and hydrophobic surfaces. • Neuroblastoma cells were arrayed on the micro-patterned NCD surface. - Abstract: Nanocrystalline diamond (NCD) film surfaces were modified with fluorine or oxygen by plasma treatment in an O{sub 2} or C{sub 3}F{sub 8} gas environment in order to induce wettability. The oxygenated-NCD (O-NCD) film surface was hydrophilic and the fluorinated-NCD (F-NCD) surface was hydrophobic. The efficiency of early cell adhesion, which is dependent on the wettability of the cell culture plate and necessary for the growth and proliferation of cells, was 89.62 ± 3.92% on the O-NCD film and 7.78 ± 0.77% on the F-NCD film surface after 3 h of cell culture. The wettability of the NCD film surface was artificially modified using a metal mask and plasma treatment to fabricate a micro-pattern. Four types of micro-patterns were fabricated (line, circle, mesh, and word) on the NCD film surface. We precisely arrayed the neuroblastoma cells on the micro-patterned NCD film surfaces by controlling the surface wettability and cell seeding density. The neuroblastoma cells adhered and proliferated along the O-NCD film surface.

  9. Endothelial cell behaviour on gas-plasma-treated PLA surfaces: the roles of surface chemistry and roughness.

    Science.gov (United States)

    Shah, Amita; Shah, Sarita; Mani, Gopinath; Wenke, Joseph; Agrawal, Mauli

    2011-04-01

    Glow-discharge gas-plasma (GP) treatment has been shown to induce surface modifications such that cell adhesion and growth are enhanced. However, it is not known which gas used in GP treatment is optimal for endothelial cell function. Polylactic acid (PLA) films treated oxygen, argon, or nitrogen GP were characterized using contact angles, scanning electron microscopy, atomic force microscopy, optical profilometry, and x-ray photoelectron spectroscopy. All three GP treatments decreased the carbon atomic concentration and surface roughness and increased the oxygen atomic concentration. Human umbilical vein endothelial cells were cultured on the PLA films for up to 7 days. Based on proliferation and live/dead assays, surface chemistry was shown to have the greatest effect on the attachment, proliferation, and viability of these cells, while roughness did not have a significant influence. Of the different gases, endothelial cell viability, attachment and proliferation were most significantly increased on PLA surfaces treated with oxygen and argon gas plasma. Copyright © 2010 John Wiley & Sons, Ltd.

  10. Roles for SH2 and SH3 domains in Lyn kinase association with activated FcepsilonRI in RBL mast cells revealed by patterned surface analysis.

    Science.gov (United States)

    Hammond, Stephanie; Wagenknecht-Wiesner, Alice; Veatch, Sarah L; Holowka, David; Baird, Barbara

    2009-10-01

    In mast cells, antigen-mediated cross-linking of IgE bound to its high-affinity surface receptor, FcepsilonRI, initiates a signaling cascade that culminates in degranulation and release of allergic mediators. Antigen-patterned surfaces, in which the antigen is deposited in micron-sized features on a silicon substrate, were used to examine the spatial relationship between clustered IgE-FcepsilonRI complexes and Lyn, the signal-initiating tyrosine kinase. RBL mast cells expressing wild-type Lyn-EGFP showed co-redistribution of this protein with clustered IgE receptors on antigen-patterned surfaces, whereas Lyn-EGFP containing an inhibitory point mutation in its SH2 domain did not significantly accumulate with the patterned antigen, and Lyn-EGFP with an inhibitory point mutation in its SH3 domain exhibited reduced interactions. Our results using antigen-patterned surfaces and quantitative cross-correlation image analysis reveal that both the SH2 and SH3 domains contribute to interactions between Lyn kinase and cross-linked IgE receptors in stimulated mast cells.

  11. Plasminogen and angiostatin interact with heat shock proteins.

    Science.gov (United States)

    Dudani, Anil K; Mehic, Jelica; Martyres, Anthony

    2007-06-01

    Previous studies from this laboratory have demonstrated that plasminogen and angiostatin bind to endothelial cell (EC) surface-associated actin via their kringles in a specific manner. Heat shock proteins (hsps) like hsp 27 are constitutively expressed by vascular ECs and regulate actin polymerization, cell growth, and migration. Since many hsps have also been found to be highly abundant on cell surfaces and there is evidence that bacterial surface hsps may interact with human plasminogen, the purpose of this study was to determine whether human plasminogen and angiostatin would interact with human hsps. ELISAs were developed in our laboratory to assess these interactions. It was observed that plasminogen bound to hsps 27, 60, and 70. In all cases, binding was inhibited (85-90%) by excess (50 mM) lysine indicating kringle involvement. Angiostatin predominantly bound to hsp 27 and to hsp 70 in a concentration- and kringle-dependent manner. As observed previously for actin, there was concentration-dependent inhibition of angiostatin's interaction with hsp 27 by plasminogen. In addition, 30-fold molar excess actin inhibited (up to 50%), the interaction of plasminogen with all hsps. However, 30-fold molar excess actin could only inhibit the interaction of angiostatin with hsp 27 by 15-20%. Collectively, these data indicate that (i) while plasminogen interacts specifically with hsp 27, 60, and 70, angiostatin interacts predominantly with hsp 27 and to some extent with hsp 70; (ii) plasminogen only partially displaces angiostatin's binding to hsp 27 and (iii) actin only partially displaces plasminogen/angiostatin binding to hsps. It is conceivable therefore that surface-associated hsps could mediate the binding of these ligands to cells like ECs.

  12. Argon ion beam interaction on polyethylene terephthalate surface by ...

    Indian Academy of Sciences (India)

    discharge treatment and laser irradiation are used. ... vation: where the interaction of plasma with the polymer involves both gas and surface .... that of metals [17]. ... with atmospheric constituents such as oxygen, water vapour and CO2 reduce ...

  13. Modification of surface/neuron interfaces for neural cell-type specific responses: a review

    International Nuclear Information System (INIS)

    Chen, Cen; Kong, Xiangdong; Lee, In-Seop

    2016-01-01

    Surface/neuron interfaces have played an important role in neural repair including neural prostheses and tissue engineered scaffolds. This comprehensive literature review covers recent studies on the modification of surface/neuron interfaces. These interfaces are identified in cases both where the surfaces of substrates or scaffolds were in direct contact with cells and where the surfaces were modified to facilitate cell adhesion and controlling cell-type specific responses. Different sources of cells for neural repair are described, such as pheochromocytoma neuronal-like cell, neural stem cell (NSC), embryonic stem cell (ESC), mesenchymal stem cell (MSC) and induced pluripotent stem cell (iPS). Commonly modified methods are discussed including patterned surfaces at micro- or nano-scale, surface modification with conducting coatings, and functionalized surfaces with immobilized bioactive molecules. These approaches to control cell-type specific responses have enormous potential implications in neural repair. (paper)

  14. Glycosylation Alters Dimerization Properties of a Cell-surface Signaling Protein, Carcinoembryonic Antigen-related Cell Adhesion Molecule 1 (CEACAM1)*

    Science.gov (United States)

    Zhuo, You; Yang, Jeong-Yeh; Moremen, Kelley W.; Prestegard, James H.

    2016-01-01

    Human carcinoembryonic antigen-related cell adhesion molecule 1 (C?/Au: EACAM1) is a cell-surface signaling molecule involved in cell adhesion, proliferation, and immune response. It is also implicated in cancer angiogenesis, progression, and metastasis. This diverse set of effects likely arises as a result of the numerous homophilic and heterophilic interactions that CEACAM1 can have with itself and other molecules. Its N-terminal Ig variable (IgV) domain has been suggested to be a principal player in these interactions. Previous crystal structures of the β-sandwich-like IgV domain have been produced using Escherichia coli-expressed material, which lacks native glycosylation. These have led to distinctly different proposals for dimer interfaces, one involving interactions of ABED β-strands and the other involving GFCC′C″ β-strands, with the former burying one prominent glycosylation site. These structures raise questions as to which form may exist in solution and what the effect of glycosylation may have on this form. Here, we use NMR cross-correlation measurements to examine the effect of glycosylation on CEACAM1-IgV dimerization and use residual dipolar coupling (RDC) measurements to characterize the solution structure of the non-glycosylated form. Our findings demonstrate that even addition of a single N-linked GlcNAc at potential glycosylation sites inhibits dimer formation. Surprisingly, RDC data collected on E. coli expressed material in solution indicate that a dimer using the non-glycosylated GFCC′C″ interface is preferred even in the absence of glycosylation. The results open new questions about what other factors may facilitate dimerization of CEACAM1 in vivo, and what roles glycosylation may play in heterophylic interactions. PMID:27471271

  15. Coronavirus spike-receptor interactions

    NARCIS (Netherlands)

    Mou, H.

    2015-01-01

    Coronaviruses cause important diseases in humans and animals. Coronavirus infection starts with the virus binding with its spike proteins to molecules present on the surface of host cells that act as receptors. This spike-receptor interaction is highly specific and determines the virus’ cell, tissue

  16. Surface-modified polymers for cardiac tissue engineering.

    Science.gov (United States)

    Moorthi, Ambigapathi; Tyan, Yu-Chang; Chung, Tze-Wen

    2017-09-26

    Cardiovascular disease (CVD), leading to myocardial infarction and heart failure, is one of the major causes of death worldwide. The physiological system cannot significantly regenerate the capabilities of a damaged heart. The current treatment involves pharmacological and surgical interventions; however, less invasive and more cost-effective approaches are sought. Such new approaches are developed to induce tissue regeneration following injury. Hence, regenerative medicine plays a key role in treating CVD. Recently, the extrinsic stimulation of cardiac regeneration has involved the use of potential polymers to stimulate stem cells toward the differentiation of cardiomyocytes as a new therapeutic intervention in cardiac tissue engineering (CTE). The therapeutic potentiality of natural or synthetic polymers and cell surface interactive factors/polymer surface modifications for cardiac repair has been demonstrated in vitro and in vivo. This review will discuss the recent advances in CTE using polymers and cell surface interactive factors that interact strongly with stem cells to trigger the molecular aspects of the differentiation or formulation of cardiomyocytes for the functional repair of heart injuries or cardiac defects.

  17. Interaction of antihydrogen with ordinary atoms and solid surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Froelich, Piotr, E-mail: piotr.froelich@kvac.uu.se; Voronin, Alexei [P.N. Lebedev Physical Institute (Russian Federation)

    2012-12-15

    The characteristic features of cold atom-antiatom collisions and antiatom-surface interactions are discussed and illustrated by the results for hydrogen-antihydrogen scattering and for quantum reflection of ultracold antihydrogen from a metallic surface. We discuss in some detail the case of spin-exchange in ultracold H-bar - H collisions, exposing the interplay of Coulombic, strong and dispersive forces, and demonstrating the sensitivity of the spin-exchange cross sections to hypothetical violations of Charge-Parity-Time (CPT) symmetry.

  18. Experimental and numerical modelling of surface water-groundwater flow and pollution interactions under tidal forcing

    Science.gov (United States)

    Spanoudaki, Katerina; Bockelmann-Evans, Bettina; Schaefer, Florian; Kampanis, Nikolaos; Nanou-Giannarou, Aikaterini; Stamou, Anastasios; Falconer, Roger

    2015-04-01

    continuous tide on the coastal side. The integrated surface water-groundwater numerical model IRENE (Spanoudaki et al., 2009, Spanoudaki, 2010) was also used in the study, with the numerical model predictions being compared with experimental results, which provide a valuable database for model calibration and validation. IRENE couples the 3D, non-steady state Navier-Stokes equations, after Reynolds averaging and with the assumption of hydrostatic pressure distribution, to the equations describing 3D saturated groundwater flow of constant density. The model uses the finite volume method with a cell-centered structured grid providing thus flexibility and accuracy in simulating irregular boundary geometries. A semi-implicit finite difference scheme is used to solve the surface water flow equations, while a fully implicit finite difference scheme is used for the groundwater equations. Pollution interactions are simulated by coupling the advection-diffusion equation describing the fate and transport of contaminants introduced in a 3D turbulent flow field to the partial differential equation describing the fate and transport of contaminants in 3D transient groundwater flow systems. References Ebrahimi, K., Falconer, R.A. and Lin B. (2007). Flow and solute fluxes in integrated wetland and coastal systems. Environmental Modelling and Software, 22 (9), 1337-1348. Hughes, S.A. (1995). Physical Modelling and Laboratory Techniques in Coastal Engineering. World Scientific Publishing Co. Pte. Ltd., Singapore. Kuan, W.K., Jin, G., Xin, P., Robinson, C. Gibbes, B. and Li. L. (2012). Tidal influence on seawater intrusion in unconfined coastal aquifers. Water Resources Research, 48 (2), doi:10.1029/2011WR010678. Spanoudaki, K., Stamou, A.I. and Nanou-Giannarou, A. (2009). Development and verification of a 3-D integrated surface water-groundwater model. Journal of Hydrology, 375 (3-4), 410-427. Spanoudaki, K. (2010). Integrated numerical modelling of surface water groundwater systems (in Greek

  19. Probes for anionic cell surface detection

    Science.gov (United States)

    Smith, Bradley D.

    2013-03-05

    Embodiments of the present invention are generally directed to compositions comprising a class of molecular probes for detecting the presence of anionic cell surfaces. Embodiments include compositions that are enriched for these compositions and preparations, particularly preparations suitable for use as laboratory/clinical reagents and diagnostic indicators, either alone or as part of a kit. An embodiment of the invention provides for a highly selective agent useful in the discernment and identification of dead or dying cells, such as apoptotic cells, in a relatively calcium-free environment. An embodiment of the invention provides a selective agent for the identification of bacteria in a mixed population of bacterial cells and nonbacterial cells.

  20. Metabolic behavior of cell surface biotinylated proteins

    International Nuclear Information System (INIS)

    Hare, J.F.; Lee, E.

    1989-01-01

    The turnover of proteins on the surface of cultured mammalian cells was measured by a new approach. Reactive free amino or sulfhydryl groups on surface-accessible proteins were derivatized with biotinyl reagents and the proteins solubilized from culture dishes with detergent. Solubilized, biotinylated proteins were then adsorbed onto streptavidin-agarose, released with sodium dodecyl sulfate and mercaptoethanol, and separated on polyacrylamide gels. Biotin-epsilon-aminocaproic acid N-hydroxysuccinimide ester (BNHS) or N-biotinoyl-N'-(maleimidohexanoyl)hydrazine (BM) were the derivatizing agents. Only 10-12 bands were adsorbed onto streptavidin-agarose from undervatized cells or from derivatized cells treated with free avidin at 4 degrees C. Two-dimensional isoelectric focusing-sodium dodecyl sulfate gel electrophoresis resolved greater than 100 BNHS-derivatized proteins and greater than 40 BM-derivatized proteins. There appeared to be little overlap between the two groups of derivatized proteins. Short-term pulse-chase studies showed an accumulation of label into both groups of biotinylated proteins up until 1-2 h of chase and a rapid decrease over the next 1-5 h. Delayed appearance of labeled protein at the cell surface was attributed to transit time from site of synthesis. The unexpected and unexplained rapid disappearance of pulse-labeled proteins from the cell surface was invariant for all two-dimensionally resolved proteins and was sensitive to temperature reduction to 18 degrees C. Long-term pulse-chase experiments beginning 4-8 h after the initiation of chase showed the disappearance of derivatized proteins to be a simple first-order process having a half-life of 115 h in the case of BNHS-derivatized proteins and 30 h in the case of BM-derivatized proteins

  1. Cell surface hydrophobicity of dental plaque microorganisms in situ.

    OpenAIRE

    Rosenberg, M; Judes, H; Weiss, E

    1983-01-01

    The cell surface hydrophobicity of bacteria obtained directly from human tooth surfaces was assayed by measuring their adherence to liquid hydrocarbons. Fresh samples of supragingival dental plaque were washed and dispersed in buffer. Adherence of the plaque microorganisms to hexadecane, octane, and xylene was tested turbidimetrically and by direct microscopic observation. The results clearly show that the vast majority of bacteria comprising dental plaque exhibit pronounced cell surface hydr...

  2. Cytochrome c interaction with hematite ({alpha}-Fe{sub 2}O{sub 3}) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Eggleston, Carrick M. [Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071 (United States)]. E-mail: carrick@uwyo.edu; Khare, Nidhi [Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071 (United States); Lovelace, David M. [Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071 (United States)

    2006-02-15

    The interaction of metalloproteins such as cytochromes with oxides is of interest for a number of reasons, including molecular catalysis of environmentally important mineral-solution electron transfer reactions (e.g., dehalogenations) and photovoltaic applications. Iron reduction by bacteria, thought to be cytochrome mediated, is of interest for geochemical and environmental remediation reasons. As a baseline for understanding cytochrome interaction with ferric oxide surfaces, we report on the interaction of mitochondrial cytochrome c (Mcc), a well-studied protein, with hematite ({alpha}-Fe{sub 2}O{sub 3}) surfaces. Mcc sorbs strongly to hematite from aqueous solution in a narrow pH range corresponding to opposite charge on Mcc and hematite (between pH 8.5 and 10, Mcc is positively charged and hematite surfaces are negatively charged). Cyclic voltammetry of Mcc using hematite electrodes gives redox potentials characteristic of Mcc in a native conformational state, with no evidence for unfolding on the hematite surface. Atomic force microscopy imaging is consistent with a loosely attached adsorbate that is easily deformed by the AFM tip. In phosphate-containing solution, Mcc adhers to the surface more strongly. These results establish hematite as a viable material for electrochemical and spectroscopic characterization of cytochrome-mineral interaction.

  3. From single cells to tissues: interactions between the matrix and human breast cells in real time.

    Directory of Open Access Journals (Sweden)

    Clifford Barnes

    Full Text Available Mammary gland morphogenesis involves ductal elongation, branching, and budding. All of these processes are mediated by stroma--epithelium interactions. Biomechanical factors, such as matrix stiffness, have been established as important factors in these interactions. For example, epithelial cells fail to form normal acinar structures in vitro in 3D gels that exceed the stiffness of a normal mammary gland. Additionally, heterogeneity in the spatial distribution of acini and ducts within individual collagen gels suggests that local organization of the matrix may guide morphogenesis. Here, we quantified the effects of both bulk material stiffness and local collagen fiber arrangement on epithelial morphogenesis.The formation of ducts and acini from single cells and the reorganization of the collagen fiber network were quantified using time-lapse confocal microscopy. MCF10A cells organized the surrounding collagen fibers during the first twelve hours after seeding. Collagen fiber density and alignment relative to the epithelial surface significantly increased within the first twelve hours and were a major influence in the shaping of the mammary epithelium. The addition of Matrigel to the collagen fiber network impaired cell-mediated reorganization of the matrix and increased the probability of spheroidal acini rather than branching ducts. The mechanical anisotropy created by regions of highly aligned collagen fibers facilitated elongation and branching, which was significantly correlated with fiber organization. In contrast, changes in bulk stiffness were not a strong predictor of this epithelial morphology.Localized regions of collagen fiber alignment are required for ductal elongation and branching suggesting the importance of local mechanical anisotropy in mammary epithelial morphogenesis. Similar principles may govern the morphology of branching and budding in other tissues and organs.

  4. Effects of the nanotopographic surface structure of commercially pure titanium following anodization–hydrothermal treatment on gene expression and adhesion in gingival epithelial cells

    International Nuclear Information System (INIS)

    Takebe, J.; Miyata, K.; Miura, S.; Ito, S.

    2014-01-01

    The long-term stability and maintenance of endosseous implants with anodized–hydrothermally treated commercially pure titanium surfaces and a nanotopographic structure (SA-treated c.p.Ti) depend on the barrier function provided by the interface between the transmucosal portion of the implant surface and the peri-implant epithelium. This study investigated the effects of extracellular and intracellular gene expression in adherent gingival epithelial cells cultured for 1–7 days on SA-treated c.p.Ti implant surfaces compared to anodic oxide (AO) c.p.Ti and c.p.Ti disks. Scanning electron microscopy (SEM) showed filopodium-like extensions bound closely to the nanotopographic structure of SA-treated c.p.Ti at day 7 of culture. Gene expressions of focal adhesion kinase, integrin-α6β4, and laminin-5 (α3, β3, γ2) were significantly higher on SA-treated c.p.Ti than on c.p.Ti or AO c.p.Ti after 7 days (P < 0.05). Our results confirmed that gingival epithelial cells adhere to SA-treated c.p.Ti as the transmucosal portion of an implant, and that this interaction markedly improves expression of focal adhesion molecules and enhances the epithelial cell phenotype. The cellular gene expression responses driving extracellular and intracellular molecular interactions thus play an important role in maintenance at the interface between SA-treated c.p.Ti implant surfaces and the gingival epithelial cells. - Highlights: • SA-treated Ti provides a nanotopographic structure for clinical oral implants. • This could regulate integrin-mediated epithelial cell adhesion and gene expression. • FAK mRNA was significantly higher on SA-treated Ti. • Integrin-α6β4 and laminin-5 mRNA were significantly higher on SA-treated Ti. • Extracellular/intracellular molecular interactions play a key role on SA-treated Ti

  5. Interactions between Innate Lymphoid Cells and Cells of the Innate and Adaptive Immune System.

    Science.gov (United States)

    Symowski, Cornelia; Voehringer, David

    2017-01-01

    Type 2 innate lymphoid cells (ILC2s) are a major source of cytokines, which are also produced by Th2 cells and several cell types of the innate immune system. Work over the past few years indicates that ILC2s play a central role in regulating type 2 immune responses against allergens and helminths. ILC2s can interact with a variety of cells types of the innate and adaptive immune system by cell-cell contacts or by communication via soluble factors. In this review, we provide an overview about recent advances in our understanding how ILC2s orchestrate type 2 immune responses with focus on direct interactions between ILC2s and other cells of the immune system.

  6. The cell biology of T-dependent B cell activation

    DEFF Research Database (Denmark)

    Owens, T; Zeine, R

    1989-01-01

    The requirement that CD4+ helper T cells recognize antigen in association with class II Major Histocompatibility Complex (MHC) encoded molecules constrains T cells to activation through intercellular interaction. The cell biology of the interactions between CD4+ T cells and antigen-presenting cells...... includes multipoint intermolecular interactions that probably involve aggregation of both polymorphic and monomorphic T cell surface molecules. Such aggregations have been shown in vitro to markedly enhance and, in some cases, induce T cell activation. The production of T-derived lymphokines that have been...... implicated in B cell activation is dependent on the T cell receptor for antigen and its associated CD3 signalling complex. T-dependent help for B cell activation is therefore similarly MHC-restricted and involves T-B intercellular interaction. Recent reports that describe antigen-independent B cell...

  7. HAMLET interacts with histones and chromatin in tumor cell nuclei.

    Science.gov (United States)

    Düringer, Caroline; Hamiche, Ali; Gustafsson, Lotta; Kimura, Hiroshi; Svanborg, Catharina

    2003-10-24

    HAMLET is a folding variant of human alpha-lactalbumin in an active complex with oleic acid. HAMLET selectively enters tumor cells, accumulates in their nuclei and induces apoptosis-like cell death. This study examined the interactions of HAMLET with nuclear constituents and identified histones as targets. HAMLET was found to bind histone H3 strongly and to lesser extent histones H4 and H2B. The specificity of these interactions was confirmed using BIAcore technology and chromatin assembly assays. In vivo in tumor cells, HAMLET co-localized with histones and perturbed the chromatin structure; HAMLET was found associated with chromatin in an insoluble nuclear fraction resistant to salt extraction. In vitro, HAMLET bound strongly to histones and impaired their deposition on DNA. We conclude that HAMLET interacts with histones and chromatin in tumor cell nuclei and propose that this interaction locks the cells into the death pathway by irreversibly disrupting chromatin organization.

  8. A map of directional genetic interactions in a metazoan cell.

    Science.gov (United States)

    Fischer, Bernd; Sandmann, Thomas; Horn, Thomas; Billmann, Maximilian; Chaudhary, Varun; Huber, Wolfgang; Boutros, Michael

    2015-03-06

    Gene-gene interactions shape complex phenotypes and modify the effects of mutations during development and disease. The effects of statistical gene-gene interactions on phenotypes have been used to assign genes to functional modules. However, directional, epistatic interactions, which reflect regulatory relationships between genes, have been challenging to map at large-scale. Here, we used combinatorial RNA interference and automated single-cell phenotyping to generate a large genetic interaction map for 21 phenotypic features of Drosophila cells. We devised a method that combines genetic interactions on multiple phenotypes to reveal directional relationships. This network reconstructed the sequence of protein activities in mitosis. Moreover, it revealed that the Ras pathway interacts with the SWI/SNF chromatin-remodelling complex, an interaction that we show is conserved in human cancer cells. Our study presents a powerful approach for reconstructing directional regulatory networks and provides a resource for the interpretation of functional consequences of genetic alterations.

  9. Selective interaction of heparin with the variable region 3 within surface glycoprotein of laboratory-adapted feline immunodeficiency virus.

    Directory of Open Access Journals (Sweden)

    Qiong-Ying Hu

    Full Text Available Heparan sulfate proteoglycans (HSPG can act as binding receptors for certain laboratory-adapted (TCA strains of feline immunodeficiency virus (FIV and human immunodeficiency virus (HIV. Heparin, a soluble heparin sulfate (HS, can inhibit TCA HIV and FIV entry mediated by HSPG interaction in vitro. In the present study, we further determined the selective interaction of heparin with the V3 loop of TCA of FIV. Our current results indicate that heparin selectively inhibits infection by TCA strains, but not for field isolates (FS. Heparin also specifically interferes with TCA surface glycoprotein (SU binding to CXCR4, by interactions with HSPG binding sites on the V3 loop of the FIV envelope protein. Peptides representing either the N- or C-terminal side of the V3 loop and containing HSPG binding sites were able to compete away the heparin block of TCA SU binding to CXCR4. Heparin does not interfere with the interaction of SU with anti-V3 antibodies that target the CXCR4 binding region or with the interaction between FS FIV and anti-V3 antibodies since FS SU has no HSPG binding sites within the HSPG binding region. Our data show that heparin blocks TCA FIV infection or entry not only through its competition of HSPG on the cell surface interaction with SU, but also by its interference with CXCR4 binding to SU. These studies aid in the design and development of heparin derivatives or analogues that can inhibit steps in virus infection and are informative regarding the HSPG/SU interaction.

  10. Dynamic interactions of Leidenfrost droplets on liquid metal surface

    Science.gov (United States)

    Ding, Yujie; Liu, Jing

    2016-09-01

    Leidenfrost dynamic interaction effects of the isopentane droplets on the surface of heated liquid metal were disclosed. Unlike conventional rigid metal, such conductive and deformable liquid metal surface enables the levitating droplets to demonstrate rather abundant and complex dynamics. The Leidenfrost droplets at different diameters present diverse morphologies and behaviors like rotation and oscillation. Depending on the distance between the evaporating droplets, they attract and repulse each other through the curved surfaces beneath them and their vapor flows. With high boiling point up to 2000 °C, liquid metal offers a unique platform for testing the evaporating properties of a wide variety of liquid even solid.

  11. Albumin receptor effect may be due to a surface-induced conformational change in albumin

    International Nuclear Information System (INIS)

    Reed, R.G.; Burrington, C.M.

    1989-01-01

    To determine whether equilibrium binding between albumin and hepatocytes involves a cell surface receptor for albumin, we incubated freshly isolated rat hepatocytes with 125 I-albumin and determined the amount of albumin associated with the cells as a function of the total albumin concentration. The resulting two-phase binding curve showed the rat albumin-hepatocyte interaction to consist of a saturable binding interaction with a dissociation constant of 1.1 microM and 2 X 10(6) sites/cell in addition to a weak, nonsaturable binding interaction. However, the saturable binding of albumin to hepatocytes did not appear to result from the presence of an albumin receptor on the cell surface; the interaction was the same for different species of albumin, for chemically modified albumins, and for fragments of albumin representing mutually exclusive domains of the molecule. The saturable binding was, instead, found to involve a subpopulation of albumin with an enhanced affinity for the cell surface. We show that this subpopulation of albumin is generated upon contact with either solid surfaces or cell surfaces and can be transferred from one surface to another. We propose that the two-phase Scatchard binding curve and the ''albumin receptor effect'' reflect two populations of albumin that bind to the cell surface with different affinities rather than one population of albumin that binds to two classes of binding sites

  12. Quantitative comparison of a human cancer cell surface proteome between interphase and mitosis.

    Science.gov (United States)

    Özlü, Nurhan; Qureshi, Mohammad H; Toyoda, Yusuke; Renard, Bernhard Y; Mollaoglu, Gürkan; Özkan, Nazlı E; Bulbul, Selda; Poser, Ina; Timm, Wiebke; Hyman, Anthony A; Mitchison, Timothy J; Steen, Judith A

    2015-01-13

    The cell surface is the cellular compartment responsible for communication with the environment. The interior of mammalian cells undergoes dramatic reorganization when cells enter mitosis. These changes are triggered by activation of the CDK1 kinase and have been studied extensively. In contrast, very little is known of the cell surface changes during cell division. We undertook a quantitative proteomic comparison of cell surface-exposed proteins in human cancer cells that were tightly synchronized in mitosis or interphase. Six hundred and twenty-eight surface and surface-associated proteins in HeLa cells were identified; of these, 27 were significantly enriched at the cell surface in mitosis and 37 in interphase. Using imaging techniques, we confirmed the mitosis-selective cell surface localization of protocadherin PCDH7, a member of a family with anti-adhesive roles in embryos. We show that PCDH7 is required for development of full mitotic rounding pressure at the onset of mitosis. Our analysis provided basic information on how cell cycle progression affects the cell surface. It also provides potential pharmacodynamic biomarkers for anti-mitotic cancer chemotherapy. © 2014 The Authors.

  13. Analysis the complex interaction among flexible nanoparticles and materials surface in the mechanical polishing process

    Energy Technology Data Exchange (ETDEWEB)

    Han Xuesong, E-mail: hanxuesongphd@yahoo.com.cn [School of Mechanical Engineering, Tianjin University, 300072 (China); Gan, Yong X. [Department of Mechanical, Industrial and Manufacturing Engineering, University of Toledo, OH 43606 (United States)

    2011-02-01

    Mechanical polishing (MP), being the important technique of realizing the surface planarization, has already been widely applied in the area of microelectronic manufacturing and computer manufacturing technology. The surface planarization in the MP is mainly realized by mechanical process which depended on the microdynamic behavior of nanoparticle. The complex multibody interaction among nanoparticles and materials surface is different from interaction in the macroscopic multibody system which makes the traditional classical materials machining theory cannot accurately uncover the mystery of the surface generation in the MP. Large-scale classical molecular dynamic (MD) simulation of interaction among nanoparticles and solid surface has been carried out to investigate the physical essence of surface planarization. The particles with small impact angle can generate more uniform global planarization surface but the materials removal rate is lower. The shear interaction between particle and substrate may induce large friction torque and lead to the rotation of particle. The translation plus rotation makes the nanoparticle behaved like micro-milling tool. The results show that the nanoparticles may aggregrate together and form larger cluster thus deteriorate surface the quality. This MD simulation results illuminate that the f inal planarized surface can only be acquired by synergic behavior of all particles using various means such as cutting, impacting, scratching, indentation and so on.

  14. Imaging and reconstruction of cell cortex structures near the cell surface

    Science.gov (United States)

    Jin, Luhong; Zhou, Xiaoxu; Xiu, Peng; Luo, Wei; Huang, Yujia; Yu, Feng; Kuang, Cuifang; Sun, Yonghong; Liu, Xu; Xu, Yingke

    2017-11-01

    Total internal reflection fluorescence microscopy (TIRFM) provides high optical sectioning capability and superb signal-to-noise ratio for imaging of cell cortex structures. The development of multi-angle (MA)-TIRFM permits high axial resolution imaging and reconstruction of cellular structures near the cell surface. Cytoskeleton is composed of a network of filaments, which are important for maintenance of cell function. The high-resolution imaging and quantitative analysis of filament organization would contribute to our understanding of cytoskeleton regulation in cell. Here, we used a custom-developed MA-TIRFM setup, together with stochastic photobleaching and single molecule localization method, to enhance the lateral resolution of TIRFM imaging to about 100 nm. In addition, we proposed novel methods to perform filament segmentation and 3D reconstruction from MA-TIRFM images. Furthermore, we applied these methods to study the 3D localization of cortical actin and microtubule structures in U373 cancer cells. Our results showed that cortical actins localize ∼ 27 nm closer to the plasma membrane when compared with microtubules. We found that treatment of cells with chemotherapy drugs nocodazole and cytochalasin B disassembles cytoskeletal network and induces the reorganization of filaments towards the cell periphery. In summary, this study provides feasible approaches for 3D imaging and analyzing cell surface distribution of cytoskeletal network. Our established microscopy platform and image analysis toolkits would facilitate the study of cytoskeletal network in cells.

  15. Capacitance, charge dynamics, and electrolyte-surface interactions in functionalized carbide-derived carbon electrodes

    Directory of Open Access Journals (Sweden)

    Boris Dyatkin

    2015-12-01

    Full Text Available This study analyzed the dynamics of ionic liquid electrolyte inside of defunctionalized, hydrogenated, and aminated pores of carbide-derived carbon supercapacitor electrodes. The approach tailors surface functionalities and tunes nanoporous structures to decouple the influence of pore wall composition on capacitance, ionic resistance, and long-term cyclability. Quasi-elastic neutron scattering probes the self-diffusion properties and electrode-ion interactions of electrolyte molecules confined in functionalized pores. Room-temperature ionic liquid interactions in confined pores are strongest when the hydrogen-containing groups are present on the surface. This property translates into higher capacitance and greater ion transport through pores during electrochemical cycling. Unlike hydrogenated pores, aminated pores do not favorably interact with ionic liquid ions and, subsequently, are outperformed by defunctionalized surfaces.

  16. Capacitance, charge dynamics, and electrolyte-surface interactions in functionalized carbide-derived carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Dyatkin, Boris; Mamontov, Eugene; Cook, Kevin M.; Gogotsi, Yury

    2015-12-01

    This study analyzed the dynamics of ionic liquid electrolyte inside of defunctionalized, hydrogenated, and aminated pores of carbide-derived carbon supercapacitor electrodes. The approach tailors surface functionalities and tunes nanoporous structures to decouple the influence of pore wall composition on capacitance, ionic resistance, and long-term cyclability. Quasi-elastic neutron scattering probes the self-diffusion properties and electrode-ion interactions of electrolyte molecules confined in functionalized pores. Room-temperature ionic liquid interactions in confined pores are strongest when the hydrogen-containing groups are present on the surface. This property translates into higher capacitance and greater ion transport through pores during electrochemical cycling. Unlike hydrogenated pores, aminated pores do not favorably interact with ionic liquid ions and, subsequently, are outperformed by defunctionalized surfaces.

  17. Surface engineered magnetic nanoparticles for specific immunotargeting of cadherin expressing cells

    International Nuclear Information System (INIS)

    Moros, Maria; Puertas, Sara; Saez, Berta; Grazú, Valeria; Delhaes, Flavien; Feracci, Helene; De la Fuente, Jesús M

    2016-01-01

    In spite of historic advances in cancer biology and recent development of sophisticated chemotherapeutics, the outlook for patients with advanced cancer is still grim. In this sense nanoparticles (NPs), through their unique physical properties, enable the development of new approaches for cancer diagnosis and treatment. Thus far the most used active targeting scheme involves NPs functionalization with antibodies specific to molecules overexpressed on cancer cell’s surface. Therefore, such active targeting relies on differences in NPs uptake kinetics rates between tumor and healthy cells. Many cancers of epithelial origin are associated with the inappropriate expression of non-epithelial cadherins (e.g. N-, P-, -11) with concomitant loss of E-cadherin. Such phenomenon named cadherin switching favors tumor development and metastasis via interactions of tumor cells with stromal components. That is why we optimized the oriented functionalization of fluorescently labelled magnetic NPs with a novel antibody specific for the extracellular domain of cadherin-11. The obtained Ab-NPs exhibited high specificity when incubated with two cell lines used as models of tumor and healthy cells. Thus, cadherin switching offers a great opportunity for the development of active targeting strategies aimed to improve the early detection and treatment of cancer. (paper)

  18. Interactions between nano-TiO{sub 2} and the oral cavity: Impact of nanomaterial surface hydrophilicity/hydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Teubl, Birgit J.; Schimpel, Christa [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); Leitinger, Gerd [Institute of Cell Biology, Histology and Embryology, Research Unit Electron Microscopic Techniques, Medical University of Graz, 8010 (Austria); Center for Medical Research, Medical University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Bauer, Bettina [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); Fröhlich, Eleonore [Center for Medical Research, Medical University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Zimmer, Andreas [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Roblegg, Eva, E-mail: eva.roblegg@uni-graz.at [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria)

    2015-04-09

    Highlights: • Hydrophilic as well as hydrophobic TiO{sub 2} NPs agglomerated under oral physiological conditions. • Particles penetrated the upper and lower buccal epithelium, independent on the degree of hydrophilicity. • Most of the hydrophobic particles were found in vesicular structures, while hydrophilic particles were freely distributed in the cytoplasm. • Hydrophilic particles had a higher potential to trigger toxic effects (e.g., ROS) than hydrophobic particles. - Abstract: Titanium dioxide (TiO{sub 2}) nanoparticles are available in a variety of oral applications, such as food additives and cosmetic products. Thus, questions about their potential impact on the oro-gastrointestinal route rise. The oral cavity represents the first portal of entry and is known to rapidly interact with nanoparticles. Surface charge and size contribute actively to the particle–cell interactions, but the influence of surface hydrophilicity/hydrophobicity has never been shown before. This study addresses the biological impact of hydrophilic (NM 103, rutile, 20 nm) and hydrophobic (NM 104, rutile, 20 nm) TiO{sub 2} particles within the buccal mucosa. Particle characterization was addressed with dynamic light scattering and laser diffraction. Despite a high agglomeration tendency, 10% of the particles/agglomerates were present in the nanosized range and penetrated into the mucosa, independent of the surface properties. However, significant differences were observed in intracellular particle localization. NM 104 particles were found freely distributed in the cytoplasm, whereas their hydrophobic counterparts were engulfed in vesicular structures. Although cell viability/membrane integrity was not affected negatively, screening assays demonstrated that NM 104 particles showed a higher potential to decrease the physiological mitochondrial membrane potential than NM 103, resulting in a pronounced generation of reactive oxygen species.

  19. Surface Electrical Potentials of Root Cell Plasma Membranes: Implications for Ion Interactions, Rhizotoxicity, and Uptake

    Directory of Open Access Journals (Sweden)

    Yi-Min Wang

    2014-12-01

    Full Text Available Many crop plants are exposed to heavy metals and other metals that may intoxicate the crop plants themselves or consumers of the plants. The rhizotoxicity of heavy metals is influenced strongly by the root cell plasma membrane (PM surface’s electrical potential (ψ0. The usually negative ψ0 is created by negatively charged constituents of the PM. Cations in the rooting medium are attracted to the PM surface and anions are repelled. Addition of ameliorating cations (e.g., Ca2+ and Mg2+ to the rooting medium reduces the effectiveness of cationic toxicants (e.g., Cu2+ and Pb2+ and increases the effectiveness of anionic toxicants (e.g., SeO42− and H2AsO4−. Root growth responses to ions are better correlated with ion activities at PM surfaces ({IZ}0 than with activities in the bulk-phase medium ({IZ}b (IZ denotes an ion with charge Z. Therefore, electrostatic effects play a role in heavy metal toxicity that may exceed the role of site-specific competition between toxicants and ameliorants. Furthermore, ψ0 controls the transport of ions across the PM by influencing both {IZ}0 and the electrical potential difference across the PM from the outer surface to the inner surface (Em,surf. Em,surf is a component of the driving force for ion fluxes across the PM and controls ion-channel voltage gating. Incorporation of {IZ}0 and Em,surf into quantitative models for root metal toxicity and uptake improves risk assessments of toxic metals in the environment. These risk assessments will improve further with future research on the application of electrostatic theory to heavy metal phytotoxicity in natural soils and aquatic environments.

  20. Lipid vesicle-mediated affinity chromatography using magnetic activated cell sorting (LIMACS): a novel method to analyze protein-lipid interaction.

    Science.gov (United States)

    Bieberich, Erhard

    2011-04-26

    The analysis of lipid protein interaction is difficult because lipids are embedded in cell membranes and therefore, inaccessible to most purification procedures. As an alternative, lipids can be coated on flat surfaces as used for lipid ELISA and Plasmon resonance spectroscopy. However, surface coating lipids do not form microdomain structures, which may be important for the lipid binding properties. Further, these methods do not allow for the purification of larger amounts of proteins binding to their target lipids. To overcome these limitations of testing lipid protein interaction and to purify lipid binding proteins we developed a novel method termed lipid vesicle-mediated affinity chromatography using magnetic-activated cell sorting (LIMACS). In this method, lipid vesicles are prepared with the target lipid and phosphatidylserine as the anchor lipid for Annexin V MACS. Phosphatidylserine is a ubiquitous cell membrane phospholipid that shows high affinity to the protein Annexin V. Using magnetic beads conjugated to Annexin V the phosphatidylserine-containing lipid vesicles will bind to the magnetic beads. When the lipid vesicles are incubated with a cell lysate the protein binding to the target lipid will also be bound to the beads and can be co-purified using MACS. This method can also be used to test if recombinant proteins reconstitute a protein complex binding to the target lipid. We have used this method to show the interaction of atypical PKC (aPKC) with the sphingolipid ceramide and to co-purify prostate apoptosis response 4 (PAR-4), a protein binding to ceramide-associated aPKC. We have also used this method for the reconstitution of a ceramide-associated complex of recombinant aPKC with the cell polarity-related proteins Par6 and Cdc42. Since lipid vesicles can be prepared with a variety of sphingo- or phospholipids, LIMACS offers a versatile test for lipid-protein interaction in a lipid environment that resembles closely that of the cell membrane