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Sample records for surface receptor aggregates

  1. Modeling multivalent ligand-receptor interactions with steric constraints on configurations of cell surface receptor aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Monine, Michael [Los Alamos National Laboratory; Posner, Richard [TRANSLATION GENOMICS RESAEARCH INSTITUTE; Savage, Paul [BYU; Faeder, James [UNIV OF PITTSBURGH; Hlavacek, William S [UNM

    2008-01-01

    Signal transduction generally involves multivalent protein-protein interactions, which can produce various protein complexes and post-translational modifications. The reaction networks that characterize these interactions tend to be so large as to challenge conventional simulation procedures. To address this challenge, a kinetic Monte Carlo (KMC) method has been developed that can take advantage of a model specification in terms of reaction rules for molecular interactions. A set of rules implicitly defines the reactions that can occur as a result of the interactions represented by the rules. With the rule-based KMC method, explicit generation of the underlying chemical reaction network implied by rules is avoided. Here, we apply and extend this method to characterize the interactions of a trivalent ligand with a bivalent cell-surface receptor. This system is also studied experimentally. We consider the following kinetic models: an equivalent-site model, an extension of this model, which takes into account steric constraints on the configurations of receptor aggregates, and finally, a model that accounts for cyclic receptor aggregates. Simulation results for the equivalent-site model are consistent with an equilibrium continuum model. Using these models, we investigate the effects of steric constraints and the formation of cyclic aggregates on the kinetics and equilibria of small and large aggregate formation and the percolation phase transition that occurs in this system.

  2. Unbonded Aggregate Surface Roads

    Science.gov (United States)

    2006-12-01

    riding surface (DA 1990).” The grada - tions in Table 1 become finer as one proceeds from grading No. 1 to grading No. 4. Figures 1 through 4 compare...a good opportunity for quantifying changes in grada - tion under traffic. A study for this purpose, as well as for quantifying the plastic- ity of

  3. Particle aggregation during receptor-mediated endocytosis

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    Mao, Sheng; Kosmrlj, Andrej

    Receptor-mediated endocytosis of particles is driven by large binding energy between ligands on particles and receptors on a membrane, which compensates for the membrane bending energy and for the cost due to the mixing entropy of receptors. While the receptor-mediated endocytosis of individual particle is well understood, much less is known about the joint entry of multiple particles. Here, we demonstrate that the endocytosis of multiple particles leads to a kinetically driven entropic attraction, which may cause the aggregation of particles observed in experiments. During the endocytosis particles absorb nearby receptors and thus produce regions, which are depleted of receptors. When such depleted regions start overlapping, the corresponding particles experience osmotic-like attractive entropic force. If the attractive force between particles is large enough to overcome the repulsive interaction due to membrane bending, then particles tend to aggregate provided that they are sufficiently close, such that they are not completely engulfed before they come in contact. We discuss the necessary conditions for the aggregation of cylindrical particles during receptor-mediated endocytosis and comment on the generalization to spherical particles.

  4. Structural Basis for Receptor-Mediated Selective Autophagy of Aminopeptidase I Aggregates

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    Akinori Yamasaki

    2016-06-01

    Full Text Available Selective autophagy mediates the degradation of various cargoes, including protein aggregates and organelles, thereby contributing to cellular homeostasis. Cargo receptors ensure selectivity by tethering specific cargo to lipidated Atg8 at the isolation membrane. However, little is known about the structural requirements underlying receptor-mediated cargo recognition. Here, we report structural, biochemical, and cell biological analysis of the major selective cargo protein in budding yeast, aminopeptidase I (Ape1, and its complex with the receptor Atg19. The Ape1 propeptide has a trimeric coiled-coil structure, which tethers dodecameric Ape1 bodies together to form large aggregates. Atg19 disassembles the propeptide trimer and forms a 2:1 heterotrimer, which not only blankets the Ape1 aggregates but also regulates their size. These receptor activities may promote elongation of the isolation membrane along the aggregate surface, enabling sequestration of the cargo with high specificity.

  5. Cytosolic Fc receptor TRIM21 inhibits seeded tau aggregation.

    Science.gov (United States)

    McEwan, William A; Falcon, Benjamin; Vaysburd, Marina; Clift, Dean; Oblak, Adrian L; Ghetti, Bernardino; Goedert, Michel; James, Leo C

    2017-01-17

    Alzheimer's disease (AD) and other neurodegenerative disorders are associated with the cytoplasmic aggregation of microtubule-associated protein tau. Recent evidence supports transcellular transfer of tau misfolding (seeding) as the mechanism of spread within an affected brain, a process reminiscent of viral infection. However, whereas microbial pathogens can be recognized as nonself by immune receptors, misfolded protein assemblies evade detection, as they are host-derived. Here, we show that when misfolded tau assemblies enter the cell, they can be detected and neutralized via a danger response mediated by tau-associated antibodies and the cytosolic Fc receptor tripartite motif protein 21 (TRIM21). We developed fluorescent, morphology-based seeding assays that allow the formation of pathological tau aggregates to be measured in situ within 24 h in the presence of picomolar concentrations of tau seeds. We found that anti-tau antibodies accompany tau seeds into the cell, where they recruit TRIM21 shortly after entry. After binding, TRIM21 neutralizes tau seeds through the activity of the proteasome and the AAA ATPase p97/VCP in a similar manner to infectious viruses. These results establish that intracellular antiviral immunity can be redirected against host-origin endopathogens involved in neurodegeneration.

  6. Aggregation of amyloidogenic peptides near hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Brovchenko, Ivan; Singh, Gurpreet; Winter, Roland

    2009-07-21

    The general effect of surface hydrophobicity/hydrophilicity on the aggregation of peptides is studied by simulations of oversaturated aqueous solutions of hydrophobic and hydrophilic amyloidogenic peptides. Peptide aggregation was studied in bulk solution, in solutions confined between hydrophobic boundaries (smooth planar paraffin-like surfaces and liquid-vapor interfaces) and in solutions confined between hydrophilic surfaces (smooth planar silica-like surfaces). Aggregation of hydrophobic peptides strongly enhances due to the confinement between hydrophobic surfaces with all peptides adsorbed at the boundaries and aligned predominantly parallel to them. In the other three cases considered, the peptides are repelled from the walls and do not reveal orientational ordering with respect to the surface. The degree of peptide aggregation in these cases is only slightly affected by the confinement (it is enhanced for hydrophobic peptides and decreased for hydrophilic peptides). Our results show that even a single environmental factor such as water-mediated peptide-surface interaction has a drastic effect on the degree and character of peptide aggregation. A wide diversity of possible scenarios can be expected when specific peptide-surface interactions are additionally taken into account.

  7. Benefits of aggregates surface modification in concrete production

    Science.gov (United States)

    Junak, J.; Sicakova, A.

    2017-10-01

    In our study, recycled concrete aggregates (RCA), which surfaces had been modified by geopolymer material based on coal fly ash, were used to produce the concrete samples. In these samples, fraction 4/8 mm was replaced by recycled concrete aggregate with a range of 100%. To modify the surface of RCA was “Solo” and “Triple stage” modification used. On these samples real density, total water absorption and compressive strength were examined after 28, 90, 180 and 365 days of hardening. The highest compressive strength 56.8 MPa, after 365 days hardening, reached sample which had improved RCA surface by “Triple stage mixing”.

  8. From aggregative adsorption to surface depletion

    DEFF Research Database (Denmark)

    Rother, Gernot; Müter, Dirk; Bock, Henry

    2017-01-01

    Adsorption of a short-chain nonionic amphiphile (C6E3) at the surface of mesoporous silica glass (CPG) was studied by a combination of adsorption measurements and mesoscale simulations. Adsorption measurements covering a wide composition range of the C6E3 + water system show that no adsorption...... occurs up to the critical micelle concentration, at which a sharp increase of adsorption is observed that is attributed to ad-micelle formation at the pore walls. Intriguingly, as the concentration is increased further, the surface excess of the amphiphile begins to decrease and eventually becomes...... negative, which corresponds to preferential adsorption of water rather than amphiphile at high amphiphile concentrations. The existence of such a surface-azeotropic point has not previously been reported in the surfactant adsorption field. Dissipative particle dynamics simulations were performed to reveal...

  9. Peptides that form β-sheets on hydrophobic surfaces accelerate surface-induced insulin amyloidal aggregation.

    Science.gov (United States)

    Nault, Laurent; Vendrely, Charlotte; Bréchet, Yves; Bruckert, Franz; Weidenhaupt, Marianne

    2013-05-02

    Interactions between proteins and material or cellular surfaces are able to trigger protein aggregation in vitro and in vivo. The human insulin peptide segment LVEALYL is able to accelerate insulin aggregation in the presence of hydrophobic surfaces. We show that this peptide needs to be previously adsorbed on a hydrophobic surface to induce insulin aggregation. Moreover, the study of different mutant peptides proves that its sequence is less important than the secondary structure of the adsorbed peptide on the surface. Indeed, these pro-aggregative peptides act by providing stable β-sheets to incoming insulin molecules, thereby accelerating insulin adsorption locally and facilitating the conformational changes required for insulin aggregation. Conversely, a peptide known to form α-helices on hydrophobic surfaces delays insulin aggregation. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  10. Predicting the Wear of High Friction Surfacing Aggregate

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    David Woodward

    2017-05-01

    Full Text Available High friction surfacing (HFS is a specialist type of road coating with very high skid resistance. It is used in the UK at locations where there is significant risk of serious or fatal accidents. This paper considers the aggregate used in HFS. Calcined bauxite is the only aggregate that provides the highest levels of skid resistance over the longest period. No naturally occurring aggregate has been found to give a comparable level of in-service performance. This paper reviews the historical development of HFS in the UK relating to aggregate. In-service performance is predicted in the laboratory using the Wear test which subjects test specimens to an estimated 5–8 years simulated trafficking. Examples are given of Wear test data. They illustrate why calcined bauxite performs better than natural aggregate. They show how the amount of calcined bauxite can be reduced by blending with high skid resistant natural aggregates. Data from the Wear test can be related to every HFS laboratory experiment and road trial carried out in the UK for over the last 50 years. Anyone considering the prediction of HFS performance needs to carefully consider the data given in this paper with any other test method currently being considered or used to investigate HFS.

  11. Synergistic Roles for Receptor Occupancy and Aggregation in Integrin Transmembrane Function

    Science.gov (United States)

    Miyamoto, Shingo; Akiyama, Steven K.; Yamada, Kenneth M.

    1995-02-01

    Integrin receptors mediate cell adhesion, signal transduction, and cytoskeletal organization. How a single transmembrane receptor can fulfill multiple functions was clarified by comparing roles of receptor occupancy and aggregation. Integrin occupancy by monovalent ligand induced receptor redistribution, but minimal tyrosine phosphorylation signaling or cytoskeletal protein redistribution. Aggregation of integrins by noninhibitory monoclonal antibodies on beads induced intracellular accumulations of pp125FAK and tensin, as well as phosphorylation, but no accumulation of other cytoskeletal proteins such as talin. Combining antibody-mediated clustering with monovalent ligand occupancy induced accumulation of seven cytoskeletal proteins, including α-actinin, talin, and F-actin, thereby mimicking multivalent interactions with fibronectin or polyvalent peptides. Integrins therefore mediate a complex repertoire of functions through the distinct effects of receptor aggregation, receptor occupancy, or both together.

  12. Identification of aggregates for Tennessee bituminous surface courses

    Science.gov (United States)

    Sauter, Heather Jean

    Tennessee road construction is a major venue for federal and state spending. Tax dollars each year go to the maintenance and construction of roads. One aspect of highway construction that affects the public is the safety of its state roads. There are many factors that affect the safety of a given road. One factor that was focused on in this research was the polish resistance capabilities of aggregates. Several pre-evaluation methods have been used in the laboratory to predict what will happen in a field situation. A new pre-evaluation method was invented that utilized AASHTO T 304 procedure upscaled to accommodate surface bituminous aggregates. This new method, called the Tennessee Terminal Textural Condition Method (T3CM), was approved by Tennessee Department of Transportation to be used as a pre-evaluation method on bituminous surface courses. It was proven to be operator insensitive, repeatable, and an accurate indication of particle shape and texture. Further research was needed to correlate pre-evaluation methods to the current field method, ASTM E 274-85 Locked Wheel Skid Trailer. In this research, twenty-five in-place bituminous projects and eight source evaluations were investigated. The information gathered would further validate the T3CM and find the pre-evaluation method that best predicted the field method. In addition, new sources of aggregates for bituminous surface courses were revealed. The results of this research have shown T3CM to be highly repeatable with an overall coefficient of variation of 0.26% for an eight sample repeatability test. It was the best correlated pre-evaluation method with the locked wheel skid trailer method giving an R2 value of 0.3946 and a Pearson coefficient of 0.710. Being able to predict field performance of aggregates prior to construction is a powerful tool capable of saving time, money, labor, and possibly lives.

  13. Aggregation of macrophages and fibroblasts is inhibited by a monoclonal antibody to the hyaluronate receptor

    Energy Technology Data Exchange (ETDEWEB)

    Green, S.J.; Underhill, C.B. (Georgetown Univ. Medical Center, Washington, DC (USA)); Tarone, G. (Univ. of Turin (Italy))

    1988-10-01

    To examine the role of the hyaluronate receptor in cell to cell adhesion, the authors have employed the K-3 monoclonal antibody (MAb) which specifically binds to the hyaluronate receptor and blocks its ability to interact with hyaluronate. In the first set of experiments, they investigated the spontaneous aggregation of SV-3T3 cells, which involves two distinct mechanisms, one of which is dependent upon the presence of divalent cation and the other is independent. The divalent cation-independent aggregation was found to be completely inhibited by both intact and Fab fragments of the K-3 MAb. In contrast, the K-3 MAb had no effect on the divalent cation-dependent aggregation of cells. In a second set of experiments, we examined alveolar macrophages. The presence of hyaluronate receptors on alveolar macrophages was demonstrated by the fact that detergent extracts of these cells could bind ({sup 3})hyaluronate, and this binding was blocked by the K-3 MAb. Immunoblot analysis of alveolar macrophages showed that the hyaluronate receptor had a M{sub r} of 99,500, which is considerably larger than the 85,000 M{sub r} for that on BHK cells. When hyaluronate was added to suspensions of alveolar macrophages, the cells were induced to aggregate. This effect was inhibited by the K-3 MAb, suggesting that the hyaluronate-induced aggregation was mediated by the receptor.

  14. Protein structural perturbation and aggregation on homogeneous surfaces.

    Science.gov (United States)

    Sethuraman, Ananthakrishnan; Belfort, Georges

    2005-02-01

    We have demonstrated that globular proteins, such as hen egg lysozyme in phosphate buffered saline at room temperature, lose native structural stability and activity when adsorbed onto well-defined homogeneous solid surfaces. This structural loss is evident by alpha-helix to turns/random during the first 30 min and followed by a slow alpha-helix to beta-sheet transition. Increase in intramolecular and intermolecular beta-sheet content suggests conformational rearrangement and aggregation between different protein molecules, respectively. Amide I band attenuated total reflection/Fourier transformed infrared (ATR/FTIR) spectroscopy was used to quantify the secondary structure content of lysozyme adsorbed on six different self-assembled alkanethiol monolayer surfaces with -CH3, -OPh, -CF3, -CN, -OCH3, and -OH exposed functional end groups. Activity measurements of adsorbed lysozyme were in good agreement with the structural perturbations. Both surface chemistry (type of functional groups, wettability) and adsorbate concentration (i.e., lateral interactions) are responsible for the observed structural changes during adsorption. A kinetic model is proposed to describe secondary structural changes that occur in two dynamic phases. The results presented in this article demonstrate the utility of the ATR/FTIR spectroscopic technique for in situ characterization of protein secondary structures during adsorption on flat surfaces.

  15. Affinity labeling of a human platelet membrane protein with 5'-p-fluorosulfonylbenzoyl adenosine. Concomitant inhibition of ADP-induced platelet aggregation and fibrinogen receptor exposure.

    Science.gov (United States)

    Figures, W R; Niewiarowski, S; Morinelli, T A; Colman, R F; Colman, R W

    1981-08-10

    Incubation of washed human blood platelets with 5'-p-fluorosulfonylbenzoyl [3H]adenosine (FSBA) covalently labels a single polypeptide of Mr = 100,000. Protection by ADP has suggested that an ADP receptor on the platelet surface membrane was modified. The modified cells, unlike native platelets, failed to aggregate in response to ADP (100 microM) and fibrinogen (1 mg/ml). The extent of binding of 125I-fibrinogen and aggregation was inhibited to a degree related to the incorporation of 5'-p-sulfonylbenzoyl adenosine (SBA) into platelets, indicating FSBA could inhibit the exposure of fibrinogen receptors by ADP necessary for aggregation. Incubation of SBA platelets with alpha-chymotrypsin cleaved the covalently labeled polypeptide and concomitantly reversed the inhibition of aggregation and fibrinogen binding. Platelets proteolytically digested by chymotrypsin prior to exposure to FSBA did not require ADP for aggregation and fibrinogen binding. Moreover, subsequent exposure to FSBA did not inhibit aggregation or fibrinogen binding. The affinity reagent FSBA can displace fibrinogen bound to platelets in the presence of ADP, as well as promote the rapid disaggregation of the platelets. The apparent initial pseudo-first order rate constant of dissociation of fibrinogen was linearly proportional to FSBA concentrations. These studies suggest that a single polypeptide can be altered either by ADP-induced conformational changes or proteolysis by chymotrypsin to reveal latent fibrinogen receptors and promote aggregation of platelets after fibrinogen binding.

  16. Formation of aggregated nanoparticle spheres through femtosecond laser surface processing

    Science.gov (United States)

    Tsubaki, Alfred T.; Koten, Mark A.; Lucis, Michael J.; Zuhlke, Craig; Ianno, Natale; Shield, Jeffrey E.; Alexander, Dennis R.

    2017-10-01

    A detailed structural and chemical analysis of a class of self-organized surface structures, termed aggregated nanoparticle spheres (AN-spheres), created using femtosecond laser surface processing (FLSP) on silicon, silicon carbide, and aluminum is reported in this paper. AN-spheres are spherical microstructures that are 20-100 μm in diameter and are composed entirely of nanoparticles produced during femtosecond laser ablation of material. AN-spheres have an onion-like layered morphology resulting from the build-up of nanoparticle layers over multiple passes of the laser beam. The material properties and chemical composition of the AN-spheres are presented in this paper based on scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDX) analysis. There is a distinct difference in the density of nanoparticles between concentric rings of the onion-like morphology of the AN-sphere. Layers of high-density form when the laser sinters nanoparticles together and low-density layers form when nanoparticles redeposit while the laser ablates areas surrounding the AN-sphere. The dynamic nature of femtosecond laser ablation creates a variety of nanoparticles that make-up the AN-spheres including Si/C core-shell, nanoparticles that directly fragmented from the base material, nanoparticles with carbon shells that retarded oxidation, and amorphous, fully oxidized nanoparticles.

  17. Antipsychotic Drugs Inhibit Platelet Aggregation via P2Y1 and P2Y12 Receptors

    Directory of Open Access Journals (Sweden)

    Chang-Chieh Wu

    2016-01-01

    Full Text Available Antipsychotic drugs (APDs used to treat clinical psychotic syndromes cause a variety of blood dyscrasias. APDs suppress the aggregation of platelets; however, the underlying mechanism remains unknown. We first analyzed platelet aggregation and clot formation in platelets treated with APDs, risperidone, clozapine, or haloperidol, using an aggregometer and rotational thromboelastometry (ROTEM. Our data indicated that platelet aggregation was inhibited, that clot formation time was increased, and that clot firmness was decreased in platelets pretreated with APDs. We also examined the role two major adenosine diphosphate (ADP receptors, P2Y1 and P2Y12, play in ADP-mediated platelet activation and APD-mediated suppression of platelet aggregation. Our results show that P2Y1 receptor stimulation with ADP-induced calcium influx was inhibited by APDs in human and rats’ platelets, as assessed by in vitro or ex vivo approach, respectively. In contrast, APDs, risperidone and clozapine, alleviated P2Y12-mediated cAMP suppression, and the release of thromboxane A2 and arachidonic acid by activated platelets decreased after APD treatment in human and rats’ platelets. Our data demonstrate that each APD tested significantly suppressed platelet aggregation via different mechanisms.

  18. Methods for Assessing the Polishing Characteristics of Coarse Aggregates for Use in Pavement Surface Layers

    OpenAIRE

    Linbing Wang; Druta, Cristian; D. Stephen Lane

    2010-01-01

    The predominant aggregate resources located in the western parts of Virginia are carbonate rocks. The mineral components of these rocks tend to be relatively soft and subject to abrasive wear under traffic that leads to a fairly rapid smoothing of the aggregate surface and the surface of pavements containing them. This smoothing or polishing leads to a loss of surface friction and thus skid resistance of the pavement, creating potential safety issues. As a consequence, surface courses of p...

  19. Platelet receptors for the Streptococcus sanguis adhesin and aggregation-associated antigens are distinguished by anti-idiotypical monoclonal antibodies.

    Science.gov (United States)

    Gong, K; Wen, D Y; Ouyang, T; Rao, A T; Herzberg, M C

    1995-09-01

    Platelets aggregate in response to an adhesin and the platelet aggregation-associated protein (PAAP) expressed on the cell surfaces of certain strains of Streptococcus sanguis. We sought to identify the corresponding PAAP receptor and accessory adhesin binding sites on platelets. Since the adhesion(s) of S. sanguis for platelets has not been characterized, an anti-idiotype (anti-id) murine monoclonal antibody (MAb2) strategy was developed. First, MAb1s that distinguished the adhesin and PAAP antigens on the surface of S. sanguis I 133-79 were selected. Fab fragments of MAb1.2 (immunoglobulin G2b [IgG2b]; 70 pmol) reacted with 5 x 10(7) cells of S. sanguis to completely inhibit the aggregation of human platelets in plasma. Under similar conditions, MAb1.1 (IgG1) inhibited the adhesion of S. sanguis cells to platelets by a maximum of 34%, with a comparatively small effect on platelet aggregation. Together, these two MAb1s inhibited S. sanguis-platelet adhesion by 63%. In Western immunoblots, both MAb1s reacted with S. sanguis 133-79 87- and 150-kDa surface proteins and MAb1.2 also reacted with purified type I collagen. The hybridomas producing MAb1.1 and MAb1.2 were then injected into BALB/c mice. Enlarged spleens were harvested, and a panel of MAb2 hybridomas was prepared. To identify anti-ids against the specific MAb1s, the MAb2 panel was screened by enzyme-linked immunosorbent assay for reaction with rabbit polyclonal IgG antibodies against the 87- and 150-kDa antigens. The reactions between the specific rabbit antibodies and anti-ids were inhibited by the 87- and 150-kDa antigens. When preincubated with platelets, MAb2.1 (counterpart of MAb1.1) inhibited adhesion to platelets maximally by 46% and MAb2.2 (anti-MAb1.2) inhibited adhesion to platelets maximally by 35%. Together, both MAb2s inhibited the adhesion of S. sanguis to platelets by 81%. MAb2.2 also inhibited induction of platelet aggregation. MAb2.2 immunoprecipitated a biotinylated platelet membrane

  20. Role of Fc gamma receptors in the activation of neutrophils by soluble and insoluble immunoglobulin aggregates isolated from the synovial fluid of patients with rheumatoid arthritis.

    OpenAIRE

    Robinson, J J; Watson, F.; Bucknall, R. C.; Edwards, S W

    1994-01-01

    OBJECTIVES--Synovial fluid from patients with rheumatoid arthritis contains both soluble and insoluble immunoglobulin aggregates which activate reactive oxidant production in human neutrophils. The objectives were to determine the roles played by Fc gamma receptors in activation of neutrophils by these complexes. METHODS--Pronase treatment was used to remove Fc gamma RIII from the neutrophil surface and blocking monoclonal antibodies were used to prevent the binding of complexes to Fc gamma R...

  1. Adhesion Evaluation of Asphalt-Aggregate Interface Using Surface Free Energy Method

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    Jie Ji

    2017-02-01

    Full Text Available The influence of organic additives (Sasobit and RH and water on the adhesion of the asphalt-aggregate interface was studied according to the surface free energy theory. Two asphalt binders (SK-70 and SK-90, and two aggregate types (limestone and basalt were used in this study. The sessile drop method was employed to test surface free energy components of asphalt, organic additives and aggregates. The adhesion models of the asphalt-aggregate interface in dry and wet conditions were established, and the adhesion work was calculated subsequently. The energy ratios were built to evaluate the effect of organic additives and water on the adhesiveness of the asphalt-aggregate interface. The results indicate that the addition of organic additives can enhance the adhesion of the asphalt-aggregate interface in dry conditions, because organic additives reduced the surface free energy of asphalt. However, the organic additives have hydrophobic characteristics and are sensitive to water. As a result, the adhesiveness of the asphalt-aggregate interface of the asphalt containing organic additives in wet conditions sharply decreased due to water damage to asphalt and organic additives. Furthermore, the compatibility of asphalt, aggregate with organic additive was noted and discussed.

  2. The Effect of Surface Charge Saturation on Heat-induced Aggregation of Firefly Luciferase.

    Science.gov (United States)

    Gharanlar, Jamileh; Hosseinkhani, Saman; Sajedi, Reza H; Yaghmaei, Parichehr

    2015-01-01

    We present here the effect of firefly luciferase surface charge saturation and the presence of some additives on its thermal-induced aggregation. Three mutants of firefly luciferase prepared by introduction of surface Arg residues named as 2R, 3R and 5R have two, three and five additional arginine residues substituted at their surface compared to native luciferase; respectively. Turbidimetric study of heat-induced aggregation indicates that all three mutants were reproducibly aggregated at higher rates relative to wild type in spite of their higher thermostability. Among them, 2R had most evaluated propensity to heat-induced aggregation. Therefore, the hydrophilization followed by appearing of more substituted arginine residues with positive charge on the firefly luciferase surface was not reduced its thermal aggregation. Nevertheless, at the same condition in the presence of charged amino acids, e.g. Arg, Lys and Glu, as well as a hydrophobic amino acid, e.g. Val, the heat-induced aggregation of wild type and mutants of firefly luciferases was markedly decelerated than those in the absence of additives. On the basis of obtained results it seems, relinquishment of variety in charge of amino acid side chains, they via local interactions with proteins cause to decrease rate and extent of their thermal aggregation. © 2015 The American Society of Photobiology.

  3. Phenotypes of Non-Attached Pseudomonas aeruginosa Aggregates Resemble Surface Attached Biofilm

    DEFF Research Database (Denmark)

    Alhede, Morten; Kragh, Kasper Nørskov; Qvortrup, Klaus

    2011-01-01

    conditions. However, microscopic investigations of samples isolated from sites of chronic infections seem to suggest that some bacteria do not need to be attached to surfaces in order to establish chronic infections. In this study we employed scanning electron microscopy, confocal laser scanning microscopy......, RT-PCR as well as traditional culturing techniques to study the properties of Pseudomonas aeruginosa aggregates. We found that non-attached aggregates from stationary-phase cultures have comparable growth rates to surface attached biofilms. The growth rate estimations indicated that, independently...... the physiological states of the aggregates and particular matrix components. Bacterial surface-attachment and subsequent biofilm formation are considered hallmarks of the capacity of microbes to cause persistent infections. We have observed non-attached aggregates in the lungs of cystic fibrosis patients; otitis...

  4. Axisymmetric Drop Shape Analysis for Estimating the Surface Tension of Cell Aggregates by Centrifugation

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    Kalantarian, Ali; Ninomiya, Hiromasa; Saad, Sameh M.I.; David, Robert; Winklbauer, Rudolf; Neumann, A. Wilhelm

    2009-01-01

    Biological tissues behave in certain respects like liquids. Consequently, the surface tension concept can be used to explain aspects of the in vitro and in vivo behavior of multicellular aggregates. Unfortunately, conventional methods of surface tension measurement cannot be readily applied to small cell aggregates. This difficulty can be overcome by an experimentally straightforward method consisting of centrifugation followed by axisymmetric drop shape analysis (ADSA). Since the aggregates typically show roughness, standard ADSA cannot be applied and we introduce a novel numerical method called ADSA-IP (ADSA for imperfect profile) for this purpose. To examine the new methodology, embryonic tissues from the gastrula of the frog, Xenopus laevis, deformed in the centrifuge are used. It is confirmed that surface tension measurements are independent of centrifugal force and aggregate size. Surface tension is measured for ectodermal cells in four sample batches, and varies between 1.1 and 7.7 mJ/m2. Surface tension is also measured for aggregates of cells expressing cytoplasmically truncated EP/C-cadherin, and is approximately half as large. In parallel, such aggregates show a reduction in convergent extension-driven elongation after activin treatment, reflecting diminished intercellular cohesion. PMID:19217876

  5. Experimental investigation of surface modified EOF steel slag as coarse aggregate in concrete

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    Y.K. Sabapathy

    2017-10-01

    Full Text Available An experimental work was carried out to study the effect of Energy Optimizing Furnace (EOF steel slag as coarse aggregate replacement in concrete. Surface modification of slag was carried out to seal the surface voids of raw slag aggregates. Quarry dust obtained as an extractive waste from the granite stone quarries has been used as a blending material in this work. After several trials, it was found that a mix proportion of 1:6:14 (cement:quarry dust:slag aggregate was the most suitable mix ratio for the surface modification of the slag aggregates. Various mixes of concrete were prepared with different proportions of modified slag (ranging from 0% to 100% as replacements for aggregates. Three grades of concrete (20 MPa, 30 MPa and 40 MPa were used in the investigation and the concrete mixes were evaluated for compressive strength and splitting tensile strength. It was found that the compressive strength improved for 25 percent replacement of natural coarse aggregates. The splitting tensile strength was found to peak at 25 percent replacement of natural aggregates.

  6. Aggregation of selected plant growth promoting Methylobacterium strains: role of cell surface components and hydrophobicity.

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    Joe, Manoharan Melvin; Saravanan, Venkatakrishnan Sivaraj; Sa, Tongmin

    2013-03-01

    The bacterial cell surface plays a major role in the bacterial aggregation that in turn plays a positive role in affecting the bacterial dispersion and survival in soil and their ability to adhere to plant surfaces. Plant growth-promoting Methylobacterium strains, Methylobacterium goesingense CBMB5, Methylobacterium sp. CBMB12, Methylobacterium oryzae CBMB20, Methylobacterium fujisawaense CBMB37, M. oryzae CBMB110 and Methylobacterium suomiense CBMB120 were evaluated for aggregation efficiency. Aggregation occurred in all test strains under high C/N growth conditions, and the strain CBMB12 showed the highest aggregation of 53.4 % at 72 h. Disaggregation compound treatment studies revealed the role of protein-protein interaction in Methylobacterium strains except CBMB110 and CBMB120 strains, where a possible carbohydrate-protein interaction is suspected. Surface layer protein extraction by LiCl followed by SDS-PAGE analysis showed the presence of proteins at molecular weights ranging from 41 to 49 kDa. Methylobacterium strains under aggregated conditions showed increased hydrophobicity compared to the cells under standard grown conditions. A relatively higher hydrophobicity of 50.1 % as evident by the adhesion with xylene was observed with strain CBMB12 under aggregated condition. This study reports the aggregation ability in plant growth-promoting Methylobacterium strains and the possible involvement of cellular components and hydrophobicity in this phenomenon.

  7. An Amyloidogenic Sequence at the N-Terminus of the Androgen Receptor Impacts Polyglutamine Aggregation

    Science.gov (United States)

    Oppong, Emmanuel; Stier, Gunter; Gaal, Miriam; Seeger, Rebecca; Stoeck, Melanie; Delsuc, Marc-André; Cato, Andrew C. B.; Kieffer, Bruno

    2017-01-01

    The human androgen receptor (AR) is a ligand inducible transcription factor that harbors an amino terminal domain (AR-NTD) with a ligand-independent activation function. AR-NTD is intrinsically disordered and displays aggregation properties conferred by the presence of a poly-glutamine (polyQ) sequence. The length of the polyQ sequence as well as its adjacent sequence motifs modulate this aggregation property. AR-NTD also contains a conserved KELCKAVSVSM sequence motif that displays an intrinsic property to form amyloid fibrils under mild oxidative conditions. As peptide sequences with intrinsic oligomerization properties are reported to have an impact on the aggregation of polyQ tracts, we determined the effect of the KELCKAVSVSM on the polyQ stretch in the context of the AR-NTD using atomic force microscopy (AFM). Here, we present evidence for a crosstalk between the amyloidogenic properties of the KELCKAVSVSM motif and the polyQ stretch at the AR-NTD. PMID:28629183

  8. An Amyloidogenic Sequence at the N-Terminus of the Androgen Receptor Impacts Polyglutamine Aggregation

    Directory of Open Access Journals (Sweden)

    Emmanuel Oppong

    2017-06-01

    Full Text Available The human androgen receptor (AR is a ligand inducible transcription factor that harbors an amino terminal domain (AR-NTD with a ligand-independent activation function. AR-NTD is intrinsically disordered and displays aggregation properties conferred by the presence of a poly-glutamine (polyQ sequence. The length of the polyQ sequence as well as its adjacent sequence motifs modulate this aggregation property. AR-NTD also contains a conserved KELCKAVSVSM sequence motif that displays an intrinsic property to form amyloid fibrils under mild oxidative conditions. As peptide sequences with intrinsic oligomerization properties are reported to have an impact on the aggregation of polyQ tracts, we determined the effect of the KELCKAVSVSM on the polyQ stretch in the context of the AR-NTD using atomic force microscopy (AFM. Here, we present evidence for a crosstalk between the amyloidogenic properties of the KELCKAVSVSM motif and the polyQ stretch at the AR-NTD.

  9. Surface derivatization state of polystyrene latex nanoparticles determines both their potency and their mechanism of causing human platelet aggregation in vitro.

    Science.gov (United States)

    McGuinnes, Catherine; Duffin, Rodger; Brown, Simon; L Mills, Nicholas; Megson, Ian L; Macnee, William; Johnston, Shonna; Lu, Sen Lin; Tran, Lang; Li, Rufia; Wang, Xue; Newby, David E; Donaldson, Ken

    2011-02-01

    There is evidence that nanoparticles (NP) can enter the bloodstream following deposition in the lungs, where they may interact with platelets. Polystyrene latex nanoparticles (PLNP) of the same size but with different surface charge-unmodified (umPLNP), aminated (aPLNP), and carboxylated (cPLNP)-were used as model NP to study interactions with human blood and platelets. Both the cPLNP and the aPLNP caused platelet aggregation, whereas the umPLNP did not. Whereas cPLNP caused aggregation by classical upregulation of adhesion receptors, aPLNP did not upregulate adhesion receptors and appeared to act by perturbation of the platelet membrane, revealing anionic phospholipids. Neither oxidative stress generation by particles nor metal contamination was responsible for these effects, which were a result of differential surface derivatization. The study reveals that NP composed of insoluble low-toxicity material are significantly altered in their potency in causing platelet aggregation by altering the surface chemistry. The two surface modifications, aminated and carboxylated, that did cause aggregation did so by different mechanisms. The study highlights the fundamental role of surface chemistry on bioactivity of NP in a platelet activation model.

  10. Phenotypes of non-attached Pseudomonas aeruginosa aggregates resemble surface attached biofilm.

    Directory of Open Access Journals (Sweden)

    Morten Alhede

    Full Text Available For a chronic infection to be established, bacteria must be able to cope with hostile conditions such as low iron levels, oxidative stress, and clearance by the host defense, as well as antibiotic treatment. It is generally accepted that biofilm formation facilitates tolerance to these adverse conditions. However, microscopic investigations of samples isolated from sites of chronic infections seem to suggest that some bacteria do not need to be attached to surfaces in order to establish chronic infections. In this study we employed scanning electron microscopy, confocal laser scanning microscopy, RT-PCR as well as traditional culturing techniques to study the properties of Pseudomonas aeruginosa aggregates. We found that non-attached aggregates from stationary-phase cultures have comparable growth rates to surface attached biofilms. The growth rate estimations indicated that, independently of age, both aggregates and flow-cell biofilm had the same slow growth rate as a stationary phase shaking cultures. Internal structures of the aggregates matrix components and their capacity to survive otherwise lethal treatments with antibiotics (referred to as tolerance and resistance to phagocytes were also found to be strikingly similar to flow-cell biofilms. Our data indicate that the tolerance of both biofilms and non-attached aggregates towards antibiotics is reversible by physical disruption. We provide evidence that the antibiotic tolerance is likely to be dependent on both the physiological states of the aggregates and particular matrix components. Bacterial surface-attachment and subsequent biofilm formation are considered hallmarks of the capacity of microbes to cause persistent infections. We have observed non-attached aggregates in the lungs of cystic fibrosis patients; otitis media; soft tissue fillers and non-healing wounds, and we propose that aggregated cells exhibit enhanced survival in the hostile host environment, compared with non-aggregated

  11. Surface properties of heat-induced soluble soy protein aggregates of different molecular masses.

    Science.gov (United States)

    Guo, Fengxian; Xiong, Youling L; Qin, Fang; Jian, Huajun; Huang, Xiaolin; Chen, Jie

    2015-02-01

    Suspensions (2% and 5%, w/v) of soy protein isolate (SPI) were heated at 80, 90, or 100 °C for different time periods to produce soluble aggregates of different molecular sizes to investigate the relationship between particle size and surface properties (emulsions and foams). Soluble aggregates generated in these model systems were characterized by gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Heat treatment increased surface hydrophobicity, induced SPI aggregation via hydrophobic interaction and disulfide bonds, and formed soluble aggregates of different sizes. Heating of 5% SPI always promoted large-size aggregate (LA; >1000 kDa) formation irrespective of temperature, whereas the aggregate size distribution in 2% SPI was temperature dependent: the LA fraction progressively rose with temperature (80→90→100 °C), corresponding to the attenuation of medium-size aggregates (MA; 670 to 1000 kDa) initially abundant at 80 °C. Heated SPI with abundant LA (>50%) promoted foam stability. LA also exhibited excellent emulsifying activity and stabilized emulsions by promoting the formation of small oil droplets covered with a thick interfacial protein layer. However, despite a similar influence on emulsion stability, MA enhanced foaming capacity but were less capable of stabilizing emulsions than LA. The functionality variation between heated SPI samples is clearly related to the distribution of aggregates that differ in molecular size and surface activity. The findings may encourage further research to develop functional SPI aggregates for various commercial applications. © 2015 Institute of Food Technologists®

  12. Alternative aggregates and materials for high friction surface treatments.

    Science.gov (United States)

    2016-05-01

    The State of Florida has used high friction surface treatments (HFSTs) since 2006 to reduce wet weather crashes on : tight curves and intersections and to maintain bridge decks; however, the Florida Department of Transportation : (FDOT) has reported ...

  13. Competitive Protein Adsorption - Multilayer Adsorption and Surface Induced Protein Aggregation

    DEFF Research Database (Denmark)

    Holmberg, Maria; Hou, Xiaolin

    2009-01-01

    In this study, competitive adsorption of albumin and IgG (immunoglobulin G) from human serum solutions and protein mixtures onto polymer surfaces is studied by means of radioactive labeling. By using two different radiolabels (125I and 131I), albumin and IgG adsorption to polymer surfaces...... is monitored simultaneously and the influence from the presence of other human serum proteins on albumin and IgG adsorption, as well as their mutual influence during adsorption processes, is investigated. Exploring protein adsorption by combining analysis of competitive adsorption from complex solutions...... of high concentration with investigation of single protein adsorption and interdependent adsorption between two specific proteins enables us to map protein adsorption sequences during competitive protein adsorption. Our study shows that proteins can adsorb in a multilayer fashion onto the polymer surfaces...

  14. Microstructured block copolymer surfaces for control of microbe capture and aggregation

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Ryan R [ORNL; Shubert, Katherine R [ORNL; Morrell, Jennifer L. [University of Tennessee, Knoxville (UTK); Lokitz, Bradley S [ORNL; Doktycz, Mitchel John [ORNL; Retterer, Scott T [ORNL

    2014-01-01

    The capture and arrangement of surface-associated microbes is influenced by biochemical and physical properties of the substrate. In this report, we develop lectin-functionalized substrates containing patterned, three-dimensional polymeric structures of varied shapes and densities and use these to investigate the effects of topology and spatial confinement on lectin-mediated microbe capture. Films of poly(glycidyl methacrylate)-block-4,4-dimethyl-2-vinylazlactone (PGMA-b-PVDMA) were patterned on silicon surfaces into line or square grid patterns with 5 m wide features and varied edge spacing. The patterned films had three-dimensional geometries with 900 nm film thickness. After surface functionalization with wheat germ agglutinin, the size of Pseudomonas fluorescens aggregates captured was dependent on the pattern dimensions. Line patterns with edge spacing of 5 m or less led to the capture of individual microbes with minimal formation of aggregates, while grid patterns with the same spacing also captured individual microbes with further reduction in aggregation. Both geometries allowed for increases in aggregate size distribution with increased in edge spacing. These engineered surfaces combine spatial confinement with affinity-based microbe capture based on exopolysaccharide content to control the degree of microbe aggregation, and can also be used as a platform to investigate intercellular interactions and biofilm formation in microbial populations of controlled sizes.

  15. The study of pervious concrete mix proportion by the method of specific surface area of aggregate

    Science.gov (United States)

    Xiao, Liguang; Jiang, Dawei

    2017-09-01

    The purpose of this paper is to solve the shortcoming of the mix proportion of pervious concrete. So we have done the research on the measurement of the specific surface area of aggregate, and the research on the volume change of cement after hydration, and the research on the best water-binder ratio and thickness of gelled material package. The experimental results show that the equivalent method is more accurate for measuring the specific surface area of aggregate. It can better reflect the specific surface area of aggregate. Moreover, the calculation method of the mix proportion of the cementing material can improve the utilization ratio of material and the quality of pervious concrete.

  16. Ultrafast exciton migration in an HJ-aggregate: Potential surfaces and quantum dynamics

    Science.gov (United States)

    Binder, Robert; Polkehn, Matthias; Ma, Tianji; Burghardt, Irene

    2017-01-01

    Quantum dynamical and electronic structure calculations are combined to investigate the mechanism of exciton migration in an oligothiophene HJ aggregate, i.e., a combination of oligomer chains (J-type aggregates) and stacked aggregates of such chains (H-type aggregates). To this end, a Frenkel exciton model is parametrized by a recently introduced procedure [Binder et al., J. Chem. Phys. 141, 014101 (2014)] which uses oligomer excited-state calculations to perform an exact, point-wise mapping of coupled potential energy surfaces to an effective Frenkel model. Based upon this parametrization, the Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) method is employed to investigate ultrafast dynamics of exciton transfer in a small, asymmetric HJ aggregate model composed of 30 sites and 30 active modes. For a partially delocalized initial condition, it is shown that a torsional defect confines the trapped initial exciton, and planarization induces an ultrafast resonant transition between an HJ-aggregated segment and a covalently bound "dangling chain" end. This model is a minimal realization of experimentally investigated mixed systems exhibiting ultrafast exciton transfer between aggregated, highly planarized chains and neighboring disordered segments.

  17. Analysis of the evolution of the aggregate surface texture and asphalt under the effect of polishing

    OpenAIRE

    SOUDANI, Khedoudja; CEREZO, Véronique; HADDADI, Smaïl

    2015-01-01

    Skid-resistance decreases when the road surface is polished by the traffic. Skid resistance provided by the pavement surface partly depends on its surface texture that is conditioned by the road technique and its components, including petrographic and mineralogical nature of the aggregates. Moreover, the geometric profile of the road in the vertical plane is divided into different wavelength scales, megatexture, macrotexture and microtexture. Polishing by traffic predominantly affects the mic...

  18. Real-time protein aggregation monitoring with a Bloch surface wave-based approach

    Science.gov (United States)

    Santi, Sara; Barakat, Elsie; Descrovi, Emiliano; Neier, Reinhard; Herzig, Hans Peter

    2014-05-01

    The misfolding and aggregation of amyloid proteins has been associated with incurable diseases such as Alzheimer's or Parkinson's disease. In the specific case of Alzheimer's disease, recent studies have shown that cell toxicity is caused by soluble oligomeric forms of aggregates appearing in the early stages of aggregation, rather than by insoluble fibrils. Research on new strategies of diagnosis is imperative to detect the disease prior to the onset of clinical symptoms. Here, we propose the use of an optical method for protein aggregation dynamic studies using a Bloch surface wave based approach. A one dimension photonic crystal made of a periodic stack of silicon oxide and silicon nitride layers is used to excite a Bloch surface wave, which is sensitive to variation of the refractive index of an aqueous solution. The aim is to detect the early dynamic events of protein aggregation and fibrillogenesis of the amyloid-beta peptide Aβ42, which plays a central role in the onset of the Alzheimer's disease. The detection principle relies on the refractive index changes caused by the depletion of the Aβ42 monomer concentration during oligomerization and fibrillization. We demonstrate the efficacy of the Bloch surface wave approach by monitoring in real-time the first crucial steps of Aβ42 oligomerization.

  19. Influence of radioactivity on surface charging and aggregation kinetics of particles in the atmosphere.

    Science.gov (United States)

    Kim, Yong-Ha; Yiacoumi, Sotira; Lee, Ida; McFarlane, Joanna; Tsouris, Costas

    2014-01-01

    Radioactivity can influence surface interactions, but its effects on particle aggregation kinetics have not been included in transport modeling of radioactive particles. In this research, experimental and theoretical studies have been performed to investigate the influence of radioactivity on surface charging and aggregation kinetics of radioactive particles in the atmosphere. Radioactivity-induced charging mechanisms have been investigated at the microscopic level, and heterogeneous surface potential caused by radioactivity is reported. The radioactivity-induced surface charging is highly influenced by several parameters, such as rate and type of radioactive decay. A population balance model, including interparticle forces, has been employed to study the effects of radioactivity on particle aggregation kinetics in air. It has been found that radioactivity can hinder aggregation of particles because of similar surface charging caused by the decay process. Experimental and theoretical studies provide useful insights into the understanding of transport characteristics of radioactive particles emitted from severe nuclear events, such as the recent accident of Fukushima or deliberate explosions of radiological devices.

  20. Influence of mechanical stress and surface interaction on the aggregation of Aspergillus niger conidia.

    Science.gov (United States)

    Grimm, L H; Kelly, S; Völkerding, I I; Krull, R; Hempel, D C

    2005-12-30

    Productivity of fungal cultures is closely linked with their morphologic development. Morphogenesis of coagulating filamentous fungi, like Aspergillus niger, starts with aggregation of conidia, also denominated as spores. Several parameters are presumed to control this event, but little is known about their mode of action. Rational process optimization requires models that mirror the underlying reaction mechanisms. An approach in this regard is suggested and supported by experimental data. Aggregation kinetics was examined for the first 15 h of cultivation under different cultivation conditions. Mechanical stress was considered as well as pH-dependent surface interaction. Deliberations were based on a two-step aggregation mechanism. The first aggregation step is only affected by the pH-value, not by the fluid dynamic conditions in the bioreactor. The second aggregation step, in contrast, depends on the pH-value as well as on agitation and aeration induced power input. For the given experimental set-up, agitation had much more influence than aeration. In addition, hyphal growth rate was determined to be the driving force for the second aggregation step. Copyright 2005 Wiley Periodicals, Inc

  1. Microstructured Block Copolymer Surfaces for Control of Microbe Adhesion and Aggregation

    Directory of Open Access Journals (Sweden)

    Ryan R. Hansen

    2014-03-01

    Full Text Available The attachment and arrangement of microbes onto a substrate is influenced by both the biochemical and physical surface properties. In this report, we develop lectin-functionalized substrates containing patterned, three-dimensional polymeric structures of varied shapes and densities and use these to investigate the effects of topology and spatial confinement on lectin-mediated microbe immobilization. Films of poly(glycidyl methacrylate-block-4,4-dimethyl-2-vinylazlactone (PGMA-b-PVDMA were patterned on silicon surfaces into line arrays or square grid patterns with 5 μm wide features and varied pitch. The patterned films had three-dimensional geometries with 900 nm film thickness. After surface functionalization with wheat germ agglutinin, the size of Pseudomonas fluorescens aggregates immobilized was dependent on the pattern dimensions. Films patterned as parallel lines or square grids with a pitch of 10 μm or less led to the immobilization of individual microbes with minimal formation of aggregates. Both geometries allowed for incremental increases in aggregate size distribution with each increase in pitch. These engineered surfaces combine spatial confinement with affinity-based capture to control the extent of microbe adhesion and aggregation, and can also be used as a platform to investigate intercellular interactions and biofilm formation in microbial populations of controlled sizes.

  2. Involvement of cell surface TG2 in the aggregation of K562 cells triggered by gluten.

    Science.gov (United States)

    Feriotto, G; Calza, R; Bergamini, C M; Griffin, M; Wang, Z; Beninati, S; Ferretti, V; Marzola, E; Guerrini, R; Pagnoni, A; Cavazzini, A; Casciano, F; Mischiati, C

    2017-03-01

    Gluten-induced aggregation of K562 cells represents an in vitro model reproducing the early steps occurring in the small bowel of celiac patients exposed to gliadin. Despite the clear involvement of TG2 in the activation of the antigen-presenting cells, it is not yet clear in which compartment it occurs. Herein we study the calcium-dependent aggregation of these cells, using either cell-permeable or cell-impermeable TG2 inhibitors. Gluten induces efficient aggregation when calcium is absent in the extracellular environment, while TG2 inhibitors do not restore the full aggregating potential of gluten in the presence of calcium. These findings suggest that TG2 activity is not essential in the cellular aggregation mechanism. We demonstrate that gluten contacts the cells and provokes their aggregation through a mechanism involving the A-gliadin peptide 31-43. This peptide also activates the cell surface associated extracellular TG2 in the absence of calcium. Using a bioinformatics approach, we identify the possible docking sites of this peptide on the open and closed TG2 structures. Peptide docks with the closed TG2 structure near to the GTP/GDP site, by establishing molecular interactions with the same amino acids involved in stabilization of GTP binding. We suggest that it may occur through the displacement of GTP, switching the TG2 structure from the closed to the active open conformation. Furthermore, docking analysis shows peptide binding with the β-sandwich domain of the closed TG2 structure, suggesting that this region could be responsible for the different aggregating effects of gluten shown in the presence or absence of calcium. We deduce from these data a possible mechanism of action by which gluten makes contact with the cell surface, which could have possible implications in the celiac disease onset.

  3. Effects of TRA-418, a novel TP-receptor antagonist, and IP-receptor agonist, on human platelet activation and aggregation.

    Science.gov (United States)

    Miyamoto, Mitsuko; Yamada, Naohiro; Ikezawa, Shiho; Ohno, Michihiro; Otake, Atsushi; Umemura, Kazuo; Matsushita, Teruo

    2003-11-01

    [4-[2-(1,1-Diphenylethylsulfanyl)-ethyl]-3,4-dihydro-2H-benzo[1,4]oxazin-8-yloxy]-acetic acid N-Methyl-d-glucamine salt (TRA-418) has both thromboxane A2 (TP)-receptor antagonist and prostacyclin (IP)-receptor agonist properties. The present study examined the advantageous effects of TRA-418 based on the dual activities, over an agent having either activity alone and also the difference in the effects of TRA-418 and a glycoprotein alphaIIb/beta3 integrin (GPIIb/IIIa) inhibitor. TRA-418 inhibited platelet GPIIb/IIIa activation as well as P-selectin expression induced by adenosine 5'-diphosphate, thrombin receptor agonist peptide 1-6 (Ser-Phe-Leu-Leu-Arg-Asn-NH2), and U-46619 in the presence of epinephrine (U-46619+ epinephrine). TRA-418 also inhibited platelet aggregation induced by those platelet-stimulants in Ca2+ chelating anticoagulant, citrate and in nonchelating anticoagulant, d-phenylalanyl-l-prolyl-l-arginyl-chloromethyl ketone (PPACK). The TP-receptor antagonist SQ-29548 inhibited only U-46619+epinephrine-induced GPIIb/IIIa activation, P-selectin expression, and platelet aggregation. The IP-receptor agonist beraprost sodium inhibited platelet activation. Beraprost also inhibited platelet aggregation induced by platelet stimulants we tested in citrate and in PPACK. The GPIIb/IIIa inhibitor abciximab blocked GPIIb/IIIa activation and platelet aggregation. However, abciximab showed slight inhibitory effects on P-selectin expression. TRA-418 is more advantageous as an antiplatelet agent than TP-receptor antagonists or IP-receptor agonists separately used. TRA-418 showed a different inhibitory profile from abciximab in the effects on P-selectin expression.

  4. P2Y12 Receptor Blockade Augments Glycoprotein IIb‐IIIa Antagonist Inhibition of Platelet Activation, Aggregation, and Procoagulant Activity

    Science.gov (United States)

    Berny‐Lang, Michelle A.; Jakubowski, Joseph A.; Sugidachi, Atsuhiro; Barnard, Marc R.; Michelson, Alan D.; Frelinger, Andrew L.

    2013-01-01

    Background New antiplatelet agents that provide greater, more consistent inhibition of the platelet ADP receptor P2Y12 may be used in combination with glycoprotein (GP) IIb‐IIIa antagonists, but their combined effect on platelet function and procoagulant activity is not well studied. Therefore, the objective of this study was to evaluate the independent and complementary effects of P2Y12 and GPIIb‐IIIa inhibition on platelet function and procoagulant activity. Methods and Results Healthy donor blood was treated with the active metabolite of prasugrel (R‐138727 5 μmol/L), GPIIb‐IIIa antagonists (abciximab 3 μg/mL or eptifibatide 0.9 μg/mL), and combinations thereof, exposed to physiologically relevant agonists (collagen and ADP) and then evaluated for markers of platelet activation and procoagulant activity. Significant interactions between R‐138727 and GPIIb‐IIIa antagonists were observed. R‐138727 and the GPIIb‐IIIa antagonists had additive inhibitory effects on collagen‐stimulated platelet aggregation and on the collagen plus ADP–stimulated level of activated platelet surface GPIIb‐IIIa. R‐138727 and abciximab each inhibited collagen plus ADP–stimulated platelet phosphatidylserine expression and prothrombin cleavage, and the combination produced greater inhibition than achieved with abciximab alone. In contrast, eptifibatide did not inhibit, but instead enhanced, collagen plus ADP–stimulated prothrombin cleavage. Addition of R‐138727 reduced prothrombin cleavage in eptifibatide‐treated samples, suggesting a novel mechanism for potential benefit from combined prasugrel and eptifibatide treatment. Conclusions The complementary effects of abciximab and R‐138727 on platelet activation, aggregation, and procoagulant activity suggest their combined use may, to a greater degree than with either agent alone, reduce thrombus formation in vivo. PMID:23676293

  5. Influence of surface modified basalt fiber on strength of cinder lightweight aggregate concrete

    Science.gov (United States)

    Xiao, Liguang; Li, Jiheng; Liu, Qingshun

    2017-12-01

    In order to improve the bonding and bridging effect between volcanic slag lightweight aggregate concrete cement and basalt fiber, The basalt fiber was subjected to etching and roughening treatment by NaOH solution, and the surface of the basalt fiber was treated with a mixture of sodium silicate and micro-silica powder. The influence of modified basalt fiber on the strength of volcanic slag lightweight aggregate concrete was systematically studied. The experimental results show that the modified basalt fiber volcanic slag lightweight aggregate concrete has a flexural strength increased by 47%, the compressive strength is improved by 16% and the toughness is increased by 27% compared with that of the non-fiber.

  6. Response to platelet-activating factor in human platelets stored and aged in plasma. Decrease in aggregation, phosphoinositide turnover, and receptor affinity

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, S.D.; Morrison, W.J.; Klachko, D.M.

    1989-07-01

    Human platelet concentrates were stored in polyolefin bags at 22 to 24 degrees C on a horizontal shaker for up to 8 days. At different intervals, aliquots of platelet-rich plasma (PRP) were removed aseptically and five variables, i.e., platelet counts, morphology, platelet-activating factor (PAF)-stimulated aggregation, phosphoinositide turnover, and (3H)PAF binding to platelet receptors, were studied. The number of platelets did not change during the 8 days of storage. Scanning electron microscopy of the platelets revealed a gradual morphologic change from biconcave flat discs to irregular, crenated forms. The PAF-induced aggregation of platelets declined with time of storage. A decrease to 50 percent of the Day 1 aggregatory response to PAF was evident on Day 2, and there was a further decline to about 20 percent by Day 6. Similarly, PAF receptor-coupled phosphoinositide turnover, as monitored by 32P incorporation into individual phosphoinositides, decreased dramatically with storage. After 2 to 3 days of storage, the phosphoinositide turnover was reduced to 50 percent of the original response, and it continued to decline to about 25 percent of original response by Day 5 or 6. The binding of (3H)PAF to washed human platelets indicated subtle changes between Days 2 and 4, which became more noticeable by Day 6. These results have raised the possibility of changes in the number of the receptors and/or their affinity for the ligand during storage. We conclude that although the number of platelets was maintained during storage for 8 days, a general deterioration of their responses to PAF occurred at the levels of cell surface receptor, transmembrane signaling (phosphoinositide turnover), and response (aggregation).

  7. Genetic Variation in the Platelet Endothelial Aggregation Receptor 1 Gene Results in Endothelial Dysfunction.

    Directory of Open Access Journals (Sweden)

    Adam S Fisch

    Full Text Available Platelet Endothelial Aggregation Receptor 1 (PEAR1 is a newly identified membrane protein reported to be involved in multiple vascular and thrombotic processes. While most studies to date have focused on the effects of this receptor in platelets, PEAR1 is located in multiple tissues including the endothelium, where it is most highly expressed. Our first objective was to evaluate the role of PEAR1 in endothelial function by examining flow-mediated dilation of the brachial artery in 641 participants from the Heredity and Phenotype Intervention Heart Study. Our second objective was to further define the impact of PEAR1 on cardiovascular disease computationally through meta-analysis of 75,000 microarrays, yielding insights regarding PEAR1 function, and predictions of phenotypes and diseases affected by PEAR1 dysregulation. Based on the results of this meta-analysis we examined whether genetic variation in PEAR1 influences endothelial function using an ex vivo assay of endothelial cell migration. We observed a significant association between rs12041331 and flow-mediated dilation in participants of the Heredity and Phenotype Intervention Heart Study (P = 0.02. Meta-analysis results revealed that PEAR1 expression is highly correlated with several genes (e.g. ANG2, ACVRL1, ENG and phenotypes (e.g. endothelial cell migration, angiogenesis that are integral to endothelial function. Functional validation of these results revealed that PEAR1 rs12041331 is significantly associated with endothelial migration (P = 0.04. Our results suggest for the first time that genetic variation of PEAR1 is a significant determinant of endothelial function through pathways implicated in cardiovascular disease.

  8. Nucleation and growth of copper phthalocyanine aggregates deposited from solution on planar surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ghani, Fatemeh [Department of Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1 Golm, 14476 Potsdam (Germany); Gojzewski, Hubert, E-mail: hubert.gojzewski@put.poznan.pl [Department of Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1 Golm, 14476 Potsdam (Germany); Institute of Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan (Poland); Riegler, Hans [Department of Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1 Golm, 14476 Potsdam (Germany)

    2015-10-01

    Graphical abstract: - Highlights: • Copper phthalocyanine deposited on planar surfaces by 3 solution process methods. • Aggregate morphology examined for coverage extending over 3 orders of magnitude. • Morphologies vary from small individual domains to mesh-like multilayers. • Nucleation and growth model explains the observed deposit morphologies. - Abstract: Copper phthalocyanine (CuPc) dissolved in trifluoroacetic acid (TFA) is deposited on solid SiO{sub 2} surfaces by solvent evaporation. The deposited CuPc aggregates are investigated by atomic force microscopy (AFM). The CuPc deposits were prepared by spin casting, dip coating, and spray deposition. Depending on the amount of deposited CuPc the aggregate morphology ranges from small individual domains to mesh-like multilayers. Each domain/layer consists of many parallel stacks of CuPc molecules with the square, plate-like molecules piled face-wise within each stack. The parallel stacks are attached sideways (i.e., edgewise attachment molecularly) to the substrate forming “nanoribbons” with uniform thickness of about 1 nm and varying width. The thickness reflects the length of a molecular edge, the width the number of stacks. A nucleation and growth model is presented that explains the observed aggregate and multilayer morphologies as result of the combination of nucleation, transport processes and a consequence of the anisotropic intermolecular interactions due to the shape of the CuPc molecule.

  9. Discrepancies over the onset of surfactant monomer aggregation interpreted by fluorescence, conductivity and surface tension methods

    Directory of Open Access Journals (Sweden)

    Maria de Fátima Carvalho Costa

    1998-06-01

    Full Text Available Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac of polymer-surfactant complexes and the critical micellar concentration (cmc of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined, 1-butanol-sodium dodecylsulfate (SDS mixtures, solutions containing poly(ethylene oxide-SDS, poly(vinylpyrrolidone-SDS and poly(acrylic acid-alkyltrimethylammonium bromide complexes. We found differences between the cac and cmc values obtained by conductivity or surface tension and those obtained by techniques which use hydrophobic probe.

  10. Competitive protein adsorption--multilayer adsorption and surface induced protein aggregation.

    Science.gov (United States)

    Holmberg, Maria; Hou, Xiaolin

    2009-02-17

    In this study, competitive adsorption of albumin and IgG (immunoglobulin G) from human serum solutions and protein mixtures onto polymer surfaces is studied by means of radioactive labeling. By using two different radiolabels (125I and 131I), albumin and IgG adsorption to polymer surfaces is monitored simultaneously and the influence from the presence of other human serum proteins on albumin and IgG adsorption, as well as their mutual influence during adsorption processes, is investigated. Exploring protein adsorption by combining analysis of competitive adsorption from complex solutions of high concentration with investigation of single protein adsorption and interdependent adsorption between two specific proteins enables us to map protein adsorption sequences during competitive protein adsorption. Our study shows that proteins can adsorb in a multilayer fashion onto the polymer surfaces and that the outcome of IgG adsorption is much more sensitive to surface characteristics than the outcome of albumin adsorption. Using high concentrations of protein solution and hydrophobic polymer surfaces during adsorption can induce IgG aggregation, which is observed as extremely high IgG adsorptions. Besides using a more hydrophilic substrate, surface-induced IgG aggregation can be inhibited by changing the adsorption sequence of albumin and IgG.

  11. Aggregation-deficient Mutants of Streptococcus gordonii Channon Altered in Production of Cell-surface Polysaccharide and Proteins

    OpenAIRE

    McNab, R.; Jenkinson, H. F.

    2011-01-01

    Three spontaneous mutants of Streptococcus gordonii strain Channon were isolated that were deficient in cell-cell aggregation. The mutants had reduced cell-surface hydrophobicity, were impaired in saliva-mediated cell aggregation, and had greatly reduced amounts of ruthenium red stained material at their cell surfaces as visualised by electron microscopy. Alkali treatment of intact cells removed the ruthenium red-stained material together with a subset of polypeptides. One of these, a surface...

  12. Effect of mineral trioxide aggregate surface treatments on morphology and bond strength to composite resin.

    Science.gov (United States)

    Shin, Joo-Hee; Jang, Ji-Hyun; Park, Sang Hyuk; Kim, Euiseong

    2014-08-01

    The aim of this study was to evaluate the micromorphologic changes that accompany different surface treatments on mineral trioxide aggregate (MTA) and their effect on the bond strength to the composite resin with 4 adhesive systems. Three types of MTA cement, ProRoot MTA (WMTA) (Dentsply, Tulsa, OK), MTA Angelus (AMTA) (Angelus, Londrina, PR, Brazil), and Endocem MTA (EMTA) (Maruchi, Wonju, Korea), were prepared and stored for a week to encourage setting. Surface treatment was performed using phosphoric acid or self-etch primer, and an untreated MTA surface was prepared as a control. The surface changes were observed using scanning electron microscopy. MTA surfaces were bonded with 4 adhesive systems, including Scotchbond Multipurpose (3M ESPE, St Paul, MN), Single Bond 2 (3M ESPE), Clearfil SE BOND (Kuraray, Osaka, Japan), and AdheSE One F (Ivoclar Vivadent, Schaan, Liechtenstein), to evaluate the adhesive effectiveness of MTA followed by composite resin restoration. The shear bond strength of the polymerized specimens was tested. For WMTA and AMTA, untreated surfaces showed an irregular crystalline plate with clusters of globular aggregate particles. For EMTA, the untreated surface presented a reticular matrix with acicular crystals. After surface treatment, superficial crystalline structures were eroded regardless of the MTA cement and adhesive system used. WMTA bonded significantly more strongly than AMTA and EMTA, regardless of the adhesive system used. In the WMTA and AMTA groups, AdheSE One F showed the highest bond strength to the composite. For EMTA, no significant differences were found across adhesive systems. Acidic treatment of the MTA surface affected the micromorphology and the bond strength to the composite. Within the limitations of this study, using a 1-step self-etch adhesive system might result in a strong bond to WMTA when the composite resin restoration is required over MTA cement. Copyright © 2014 American Association of Endodontists

  13. Pyocyanin facilitates extracellular DNA binding to Pseudomonas aeruginosa influencing cell surface properties and aggregation.

    Science.gov (United States)

    Das, Theerthankar; Kutty, Samuel K; Kumar, Naresh; Manefield, Mike

    2013-01-01

    Pyocyanin is an electrochemically active metabolite produced by the human pathogen Pseudomonas aeruginosa. It is a recognized virulence factor and is involved in a variety of significant biological activities including gene expression, maintaining fitness of bacterial cells and biofilm formation. It is also recognized as an electron shuttle for bacterial respiration and as an antibacterial and antifungal agent. eDNA has also been demonstrated to be a major component in establishing P. aeruginosa biofilms. In this study we discovered that production of pyocyanin influences the binding of eDNA to P. aeruginosa PA14 cells, mediated through intercalation of pyocyanin with eDNA. P. aeruginosa cell surface properties including cell size (hydrodynamic diameter), hydrophobicity and attractive surface energies were influenced by eDNA in the presence of pyocyanin, affecting physico-chemical interactions and promoting aggregation. A ΔphzA-G PA14 mutant, deficient in pyocynain production, could not bind with eDNA resulting in a reduction in hydrodynamic diameter, a decrease in hydrophobicity, repulsive physico-chemical interactions and reduction in aggregation in comparison to the wildtype strain. Removal of eDNA by DNase I treatment on the PA14 wildtype strain resulted in significant reduction in aggregation, cell surface hydrophobicity and size and an increase in repulsive physico-chemical interactions, similar to the level of the ΔphzA-G mutant. The cell surface properties of the ΔphzA-G mutant were not affected by DNase I treatment. Based on these findings we propose that pyocyanin intercalation with eDNA promotes cell-to-cell interactions in P. aeruginosa cells by influencing their cell surface properties and physico-chemical interactions.

  14. Pyocyanin facilitates extracellular DNA binding to Pseudomonas aeruginosa influencing cell surface properties and aggregation.

    Directory of Open Access Journals (Sweden)

    Theerthankar Das

    Full Text Available Pyocyanin is an electrochemically active metabolite produced by the human pathogen Pseudomonas aeruginosa. It is a recognized virulence factor and is involved in a variety of significant biological activities including gene expression, maintaining fitness of bacterial cells and biofilm formation. It is also recognized as an electron shuttle for bacterial respiration and as an antibacterial and antifungal agent. eDNA has also been demonstrated to be a major component in establishing P. aeruginosa biofilms. In this study we discovered that production of pyocyanin influences the binding of eDNA to P. aeruginosa PA14 cells, mediated through intercalation of pyocyanin with eDNA. P. aeruginosa cell surface properties including cell size (hydrodynamic diameter, hydrophobicity and attractive surface energies were influenced by eDNA in the presence of pyocyanin, affecting physico-chemical interactions and promoting aggregation. A ΔphzA-G PA14 mutant, deficient in pyocynain production, could not bind with eDNA resulting in a reduction in hydrodynamic diameter, a decrease in hydrophobicity, repulsive physico-chemical interactions and reduction in aggregation in comparison to the wildtype strain. Removal of eDNA by DNase I treatment on the PA14 wildtype strain resulted in significant reduction in aggregation, cell surface hydrophobicity and size and an increase in repulsive physico-chemical interactions, similar to the level of the ΔphzA-G mutant. The cell surface properties of the ΔphzA-G mutant were not affected by DNase I treatment. Based on these findings we propose that pyocyanin intercalation with eDNA promotes cell-to-cell interactions in P. aeruginosa cells by influencing their cell surface properties and physico-chemical interactions.

  15. Self-assembled nanoparticle aggregates: Organizing disorder for high performance surface-enhanced spectroscopy

    Science.gov (United States)

    Fasolato, C.; Domenici, F.; Brasili, F.; Mura, F.; Sennato, S.; De Angelis, L.; Mazzi, E.; Bordi, F.; Postorino, P.

    2015-06-01

    The coherent oscillations of the surface electron gas, known as surface plasmons, in metal nanostructures can give rise to the localization of intense electromagnetic fields at the metal-dielectric interface. These strong fields are exploited in surface enhanced spectroscopies, such as Surface Enhanced Raman Scattering (SERS), for the detection and characterization of molecules at very low concentration. Still, the implementation of SERS-based biosensors requires a high level of reproducibility, combined with cheap and simple fabrication methods. For this purpose, SERS substrates based on self-assembled aggregates of commercial metallic nanoparticles (Nps) can meet all the above requests. Following this line, we report on a combined micro-Raman and Atomic Force Microscopy (AFM) analysis of the SERS efficiency of micrometric silver Np aggregates (enhancement factors up to 109) obtained by self-assembly. Despite the intrinsic disordered nature of these Np clusters, we were able to sort out some general rules relating the specific aggregate morphology to its plasmonic response. We found strong evidences of cooperative effects among the NPs within the cluster and namely a clear dependence of the SERS-efficiency on both the cluster area (basically linear) and the number of stacked NPs layers. A cooperative action among the superimposed layers has been proved also by electromagnetic simulations performed on simplified nanostructures consisting of stacking planes of ordered Nps. Being clear the potentialities of these disordered self-assembled clusters, in terms of both easy fabrication and signal enhancement, we developed a specific nanofabrication protocol, based on electron beam lithography and molecular functionalization, that allowed for a fine control of the Np assemblies into designed shapes fixing their area and height. In particular, we fabricated 2D ordered arrays of disordered clusters choosing gold Nps owing to their high stability. AFM measurements confirmed

  16. Self-assembled nanoparticle aggregates: Organizing disorder for high performance surface-enhanced spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fasolato, C. [Dipartimento di Fisica, Università Sapienza, Rome (Italy); Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia, Rome (Italy); Domenici, F., E-mail: fabiodomenici@gmail.com [Dipartimento di Fisica, Università Sapienza, Rome (Italy); Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Rome (Italy); Brasili, F.; Mazzi, E.; Postorino, P., E-mail: paolo.postorino@roma1.infn.it [Dipartimento di Fisica, Università Sapienza, Rome (Italy); Mura, F. [Center for Nanotechnology for Engineering (CNIS), Università Sapienza, Rome (Italy); Dipartimento di Scienze di Base Applicate all’Ingegneria, Università Sapienza, Rome (Italy); Sennato, S. [Dipartimento di Fisica, Università Sapienza, Rome (Italy); CNR-ISC UOS Sapienza, Università Sapienza, Rome (Italy); De Angelis, L. [Dipartimento di Fisica, Università Sapienza, Rome (Italy); Center for Nanophotonics, FOM Institute AMOLF, Amsterdam (Netherlands); Bordi, F. [Dipartimento di Fisica, Università Sapienza, Rome (Italy); CNR-IPCF UOS Roma, Dipartimento di Fisica, Università Sapienza, Rome (Italy)

    2015-06-23

    The coherent oscillations of the surface electron gas, known as surface plasmons, in metal nanostructures can give rise to the localization of intense electromagnetic fields at the metal-dielectric interface. These strong fields are exploited in surface enhanced spectroscopies, such as Surface Enhanced Raman Scattering (SERS), for the detection and characterization of molecules at very low concentration. Still, the implementation of SERS-based biosensors requires a high level of reproducibility, combined with cheap and simple fabrication methods. For this purpose, SERS substrates based on self-assembled aggregates of commercial metallic nanoparticles (Nps) can meet all the above requests. Following this line, we report on a combined micro-Raman and Atomic Force Microscopy (AFM) analysis of the SERS efficiency of micrometric silver Np aggregates (enhancement factors up to 10{sup 9}) obtained by self-assembly. Despite the intrinsic disordered nature of these Np clusters, we were able to sort out some general rules relating the specific aggregate morphology to its plasmonic response. We found strong evidences of cooperative effects among the NPs within the cluster and namely a clear dependence of the SERS-efficiency on both the cluster area (basically linear) and the number of stacked NPs layers. A cooperative action among the superimposed layers has been proved also by electromagnetic simulations performed on simplified nanostructures consisting of stacking planes of ordered Nps. Being clear the potentialities of these disordered self-assembled clusters, in terms of both easy fabrication and signal enhancement, we developed a specific nanofabrication protocol, based on electron beam lithography and molecular functionalization, that allowed for a fine control of the Np assemblies into designed shapes fixing their area and height. In particular, we fabricated 2D ordered arrays of disordered clusters choosing gold Nps owing to their high stability. AFM measurements

  17. Beyond the cell surface: new mechanisms of receptor function.

    Science.gov (United States)

    Ibáñez, Carlos F

    2010-05-21

    The text book view of cell surface receptors depicts them at the top of a vertical chain of command that starts with ligand binding and proceeds in a lineal fashion towards the cell nucleus. Although pedagogically useful, this view is incomplete and recent findings suggest that the extracellular domain of cell surface receptors can be a transmitter as much as a receiver in intercellular communication. GFRalpha1 is a GPI-anchored receptor for GDNF (glial cell line-derived neurotrophic factor), a neuronal growth factor with widespread functions in the developing and adult nervous system. GFRalpha1 partners with transmembrane proteins, such as the receptor tyrosine kinase RET or the cell adhesion molecule NCAM, for intracellular transmission of the GDNF signal. In addition to this canonical role, GFRalpha1 can also engage in horizontal interactions and thereby modify the function of other cell surface components. GFRalpha1 can also function as a ligand-induced adhesion cell molecule, mediating homophilic cell-cell interactions in response to GDNF. Finally, GFRalpha1 can also be released from the cell surface and act at a distance as a soluble factor together with its ligand. This plethora of unconventional mechanisms is likely to be a feature common to several other receptors and considerably expands our view of cell surface receptor function. 2010 Elsevier Inc. All rights reserved.

  18. Friction Surface Treatment Selection: Aggregate Properties, Surface Characteristics, Alternative Treatments, and Safety Effects

    OpenAIRE

    Li, Shuo; Xiong, Rui; Yu, Demei; Zhao, Guangyuan; Cong, Peiliang; Jiang, Yi

    2017-01-01

    This study aimed to evaluate the long term performance of the selected surface friction treatments, including high friction surface treatment (HFST) using calcined bauxite and steel slag, and conventional friction surfacing, in particular pavement preservation treatments such as chip seal, microsurfacing, ultrathin bonded wearing course (UBWC), and diamond grinding. This study also attempted to determine the correlation between vehicle crash and pavement surface friction, which makes it possi...

  19. Modulation of protein stability and aggregation properties by surface charge engineering.

    Science.gov (United States)

    Raghunathan, Govindan; Sokalingam, Sriram; Soundrarajan, Nagasundarapandian; Madan, Bharat; Munussami, Ganapathiraman; Lee, Sun-Gu

    2013-09-01

    An attempt to alter protein surface charges through traditional protein engineering approaches often affects the native protein structure significantly and induces misfolding. This limitation is a major hindrance in modulating protein properties through surface charge variations. In this study, as a strategy to overcome such a limitation, we attempted to co-introduce stabilizing mutations that can neutralize the destabilizing effect of protein surface charge variation. Two sets of rational mutations were designed; one to increase the number of surface charged amino acids and the other to decrease the number of surface charged amino acids by mutating surface polar uncharged amino acids and charged amino acids, respectively. These two sets of mutations were introduced into Green Fluorescent Protein (GFP) together with or without stabilizing mutations. The co-introduction of stabilizing mutations along with mutations for surface charge modification allowed us to obtain functionally active protein variants (s-GFP(+15-17) and s-GFP(+5-6)). When the protein properties such as fluorescent activity, folding rate and kinetic stability were assessed, we found the possibility that the protein stability can be modulated independently of activity and folding by engineering protein surface charges. The aggregation properties of GFP could also be altered through the surface charge engineering.

  20. In vitro effects of the glycoprotein IIb/IIIa receptor antagonists abciximab and eptifibatide on platelet aggregation in healthy cats.

    Science.gov (United States)

    Magee, Aliya N; Hogan, Daniel F; Sederquist, Kimberly A; Durham, Jaylyn A

    2014-03-01

    To determine effects of the glycoprotein IIb/IIIa receptor antagonists abciximab and eptifibatide on in vitro inhibition of cat platelets. Venous blood samples from 10 healthy cats. Blood samples were anticoagulated with hirudin. Aliquots of whole blood from each cat were allocated to 5 treatments (baseline, 50 μg of abciximab/mL, abciximab volumetric control treatment, 4 μM eptifibatide, and eptifibatide volumetric control treatment). Impedance platelet aggregometry was performed with 6.5 μM ADP or 32 μM thrombin receptor activator peptide (TRAP). Magnitude of platelet aggregation was determined by measuring the area under the curve 15 minutes after addition of ADP or TRAP. Eptifibatide caused a significant reduction in platelet aggregation, compared with baseline values, for aggregometry with both ADP (median, 50.0; range, 8 to 122 [baseline median, 306.0; baseline range, 130 to 664]) and TRAP (median, 75.5; range, 3 to 148 [baseline median, 219.0; baseline range, 97 to 578]). There was no significant difference in platelet aggregation with abciximab, the abciximab volumetric control treatment, or the eptifibatide volumetric control treatment for aggregometry with ADP or TRAP. Eptifibatide caused a significant reduction in platelet aggregation in vitro, but there was no identifiable antiplatelet effect for abciximab. Eptifibatide and abciximab have different binding and inhibitory actions; therefore, it can be hypothesized that abciximab would be ineffective in cats because of a lack of receptor binding, reduced binding kinetics, or lack of downstream signaling. Eptifibatide may be useful in identifying hyperreactive platelets in cats in an in vitro platelet inhibitory assay.

  1. NOK/STYK1 has a strong tendency towards forming aggregates and colocalises with epidermal growth factor receptor in endosomes.

    Science.gov (United States)

    Ding, Xue; Jiang, Qing-Bo; Li, Rui; Chen, Shaoyong; Zhang, Shuping

    2012-05-11

    Our previous studies showed that the overexpression of Novel Oncogene with Kinase-domain (NOK)/STYK1 led to cellular transformation, tumorigenesis and metastasis. This report characterises the subcellular distribution of NOK in HeLa cells and its localisation in early endosomes. Confocal immunolocalisation studies indicated that NOK had structural subtypes and was distributed into two distinct expression patterns: a dot pattern (DP) and an aggregation pattern (AP). The results of an immunohistochemistry (IHC) analysis of pathological tissues also showed that high expression level of endogenous NOK was expressed in an aggregate-like structure in vivo. Importantly, we found that NOK was localised in endosomes and colocalised with epidermal growth factor receptor (EGFR) in activated endosomal vesicles. However, as the stimulation time increased, NOK and EGFR began to progress through different pathways. EGFR was gradually degraded after treatment with EGF for approximately 20 min, whereas NOK levels were not reduced. This result suggests that NOK mainly plays a role in facilitating the trafficking of EGFR from early endosomes to later endosomes/lysosomes. Taken together, NOK has a strong tendency towards forming aggregates, which may have physiological implications and provide the first evidence that this novel receptor kinase is colocalised with EGFR in endosomes to participate in a post-internalisation step of EGFR. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. Design and Properties of Thin Surfacing Hot Mix Asphalt Containing Crumb Rubber as Partial Aggregate Replacement

    Science.gov (United States)

    Setyawan, Ary; Febrianto, Nugroho; Sarwono, Djoko

    2017-07-01

    Road damage caused as a result of the traffic load and environment. One method to improve the road condition is from an overlay. But the new layer on the top of the pavement structure is thick enough and elevate the surface of the pavement, so it will cause some impact on the user safety and engineering. The use of a thin layer of hot mix asphalt is an alternative to anticipate the thickness problem. Crumb rubber is a waste material that has a flexible nature, these materials are used as an aggregate replacement in the hot mix asphalt thin layer. The research was conducted to find the optimum bitumen content and optimum crumb rubber content on asphalt mixtures by the Marshall procedure. Finally, it was concluded that the addition of crumb rubber in a thin layer of hot mix asphalt indicates the better the interlocking between aggregates so that gave the better Marshall stability, the higher the flow rate, the lower the marshall quotient, reduce the void ratio. The results show that the addition of crumb rubber content as an aggregate replacement leads to the use of less optimum bitumen content.

  3. Predictive response surface model for heat-induced rheological changes and aggregation of whey protein concentrate.

    Science.gov (United States)

    Alvarez, Pedro A; Emond, Charles; Gomaa, Ahmed; Remondetto, Gabriel E; Subirade, Muriel

    2015-02-01

    Whey proteins are now far more than a by-product of cheese processing. In the last 2 decades, food manufacturers have developed them as ingredients, with the dairy industry remaining as a major user. For many applications, whey proteins are modified (denatured) to alter their structure and functional properties. The objective of this research was to study the influence of 85 to 100 °C, with protein concentration of 8% to 12%, and treatment times of 5 to 30 min, while measuring rheological properties (storage modulus, loss modulus, and complex viscosity) and aggregation (intermolecular beta-sheet formation) in dispersions of whey protein concentrate (WPC). A Box-Behnken Response Surface Methodology modeled the heat denaturation of liquid sweet WPC at 3 variables and 3 levels. The model revealed a very significant fit for viscoelastic properties, and a lesser fit for protein aggregation, at temperatures not previously studied. An exponential increase of rheological parameters was governed by protein concentration and temperature, while a modest linear relationship of aggregation was governed by temperature. Models such as these can serve as valuable guides to the ingredient and dairy industries to develop target products, as whey is a major ingredient in many functional foods. © 2015 Institute of Food Technologists®

  4. Soluble and cell surface receptors for tumor necrosis factor

    DEFF Research Database (Denmark)

    Wallach, D; Engelmann, H; Nophar, Y

    1991-01-01

    . The intracellular domains of the two receptors differ in structure, suggesting that they mediate different activities. Their extracellular domains, however, are structurally related. Both contain cysteine-rich repeats which are homologous to repeated structures found in the extracellular domains of the nerve growth...... in certain pathological situations. Release of the soluble receptors from the cells seems to occur by proteolytic cleavage of the cell surface forms and appears to be a way of down-regulating the cell response to TNF. Because of their ability to bind TNF, the soluble receptors exert an inhibitory effect...

  5. Aggregation and surface properties of F-specific RNA phages: implication for membrane filtration processes.

    Science.gov (United States)

    Langlet, Jérémie; Gaboriaud, Fabien; Duval, Jérôme F L; Gantzer, Christophe

    2008-05-01

    We report an experimental investigation of the electrokinetic properties and size variations of four F-specific bacteriophages of the types MS2, GA, Qbeta and SP (21-30 nm in diameter) over a broad range of pH values (1.5-7.5) and NaNO3 electrolyte concentrations (1-100 mM). The results obtained by dynamic light scattering show that the aggregation of SP and GA particles takes place over the whole range of pH and ionic strength conditions examined. For MS2 phages, the aggregation of MS2 particles is not observed for pH higher than the isoelectric point (pI) and large ionic strengths for which interparticular repulsive electrostatic interactions are however expected to be sufficiently screened. Aggregation of the MS2 phages, dispersed in 1 and 100 mM electrolyte concentration, occurs at pH 4, which basically corresponds to the pI as determined by electrophoresis measurements. The Qbeta particles suspended in solutions of low electrolyte concentrations aggregate at low pH values (pI approximately 3) and, unlike MS2, at large ionic strengths over the whole range of pH conditions considered in this study. These elements allow the determination of the hydrophobic sequence for the four phages SP approximately GA>Qbeta>MS2. Close inspection of the electrokinetic results reveals small to significant variations of the pI values-depending on the phage considered-with respect to the concentration of indifferent NaNO3 electrolyte. This indicates that features other than chemical and electrostatic in nature play a key role in determining the pI and more generally the electrophoretic mobility mu of viral particles. A qualitative interpretation is given and is based on the consideration of inner electro-osmotic flow within the isolated or aggregated particles. The impact of the flow properties within the particles is further in agreement with recent theoretical formalism developed for the electrokinetics of soft multiplayer particles, the phages analyzed here being some

  6. Ash aggregation enhanced by deposition and redistribution of salt on the surface of volcanic ash in eruption plumes.

    Science.gov (United States)

    Mueller, Sebastian B; Ayris, Paul M; Wadsworth, Fabian B; Kueppers, Ulrich; Casas, Ana S; Delmelle, Pierre; Taddeucci, Jacopo; Jacob, Michael; Dingwell, Donald B

    2017-03-31

    Interactions with volcanic gases in eruption plumes produce soluble salt deposits on the surface of volcanic ash. While it has been postulated that saturation-driven precipitation of salts following the dissolution of ash surfaces by condensed acidic liquids is a primary mechanism of salt formation during an eruption, it is only recently that this mechanism has been subjected to detailed study. Here we spray water and HCl droplets into a suspension of salt-doped synthetic glass or volcanic ash particles, and produce aggregates. Deposition of acidic liquid droplets on ash particles promotes dissolution of existing salts and leaches cations from the underlying material surface. The flow of liquid, due to capillary forces, will be directed to particle-particle contact points where subsequent precipitation of salts will cement the aggregate. Our data suggest that volcanically-relevant loads of surface salts can be produced by acid condensation in eruptive settings. Several minor and trace elements mobilised by surface dissolution are biologically relevant; geographic areas with aggregation-mediated ash fallout could be "hotspots" for the post-deposition release of these elements. The role of liquids in re-distributing surface salts and cementing ash aggregates also offers further insight into the mechanisms which preserve well-structured aggregates in some ash deposits.

  7. Modeling of adsorption of toxic chromium on natural and surface modified lightweight expanded clay aggregate (LECA)

    Energy Technology Data Exchange (ETDEWEB)

    Kalhori, Ebrahim Mohammadi, E-mail: zarrabi62@yahoo.com [Department of Environmental Health Engineering, Faculty of Health, Alborz University of Medical Sciences, P.O. Box No: 31485/561, Alborz, Karaj (Iran, Islamic Republic of); Yetilmezsoy, Kaan, E-mail: yetilmez@yildiz.edu.tr [Department of Environmental Engineering, Faculty of Civil Engineering, Yildiz Technical University, 34220 Davutpasa, Esenler, Istanbul (Turkey); Uygur, Nihan, E-mail: uygur.n@gmail.com [Department of Environmental Engineering, Faculty of Engineering, Adiyaman University, 02040 Altinsehir, Adiyaman (Turkey); Zarrabi, Mansur, E-mail: mansor62@gmail.com [Department of Environmental Health Engineering, Faculty of Health, Alborz University of Medical Sciences, P.O. Box No: 31485/561, Alborz, Karaj (Iran, Islamic Republic of); Shmeis, Reham M. Abu, E-mail: r.abushmeis@yahoo.com [Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Isra University, PO Box 140753, code 11814, Amman (Jordan)

    2013-12-15

    Lightweight Expanded Clay Aggregate (LECA) modified with an aqueous solution of magnesium chloride MgCl{sub 2} and hydrogen peroxide H{sub 2}O{sub 2} was used to remove Cr(VI) from aqueous solutions. The adsorption properties of the used adsorbents were investigated through batch studies, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Fluorescence Spectroscopy (XRF), and Fourier Transform Infrared (FTIR) spectroscopy. The effect created by magnesium chloride on the modification of the LECA surface was greater than that of hydrogen peroxide solution and showed a substantial increase in the specific surface area which has a value of 76.12 m{sup 2}/g for magnesium chloride modified LECA while the values of 53.72 m{sup 2}/g, and 11.53 m{sup 2}/g were found for hydrogen peroxide modified LECA and natural LECA, respectively. The extent of surface modification with enhanced porosity in modified LECA was apparent from the recorded SEM patterns. XRD and FTIR studies of themodified LECA surface did not show any structural distortion. The adsorption kinetics was found to follow the modified Freundlich kinetic model and the equilibrium data fitted the Sips and Dubinin-Radushkevich equations better than other models. Maximum sorption capacities were found to be 198.39, 218.29 and 236.24 mg/g for natural LECA, surface modified LECA with H{sub 2}O{sub 2} and surface modified LECA with MgCl{sub 2}, respectively. Adsorbents were found to have only a weak effect on conductivity and turbidity of aqueous solutions. Spent natural and surface modified LECA with MgCl{sub 2} was best regenerated with HCl solution, while LECA surface modified with H{sub 2}O{sub 2} was best regenerated with HNO{sub 3} concentrated solution. Thermal method showed a lower regeneration percentage for all spent adsorbents.

  8. Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Y. Fleger

    2009-01-01

    Full Text Available Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR and surface enhanced Raman spectroscopy (SERS are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticles evaporated on top of larger gold nanoparticles show higher SERS than gold-silver alloyed nanoparticles, in spite of the fact that the SPR peak of alloyed nanoparticles is narrower and closer to the excitation wavelength. The highest Raman enhancement was obtained for substrates with a two-peak particle size distribution for excitation wavelengths close to the SPR.

  9. Comparison of aggregating agents for the surface-enhanced Raman analysis of benzodiazepines.

    Science.gov (United States)

    Doctor, Erika L; McCord, Bruce

    2013-10-21

    Benzodiazepines are among the most prescribed compounds and are commonly present in many toxicological screens. They are also of concern forensically in cases of drug facilitated sexual assault. Currently these compounds are predominantly analyzed using immunoassay techniques; however more specific screening methods are needed. This paper demonstrates the applicability of surface enhanced Raman spectroscopy as a method for the analysis and detection of benzodiazepines. The procedure involves mixing urine extracts with gold nanoparticles and appropriate aggregating agents for trace detection of these compounds and their metabolites. In this paper we will discuss the optimization of various parameters of this technique as well as its application to screening urine samples. Eleven different benzodiazepines and metabolites were examined, including 1,2-triazolo-benzodiazepines and 1,4-benzodiazpines. Experiments were performed using four different chloride salts, MgCl2, CaCl2, KCl, and NaCl, as aggregating agents for the colloidal gold nanoparticles. Overall it was found that each aggregating agent produced different levels of signal enhancement for each drug. MgCl2 provided the lowest limit of detection at 2.5 ng mL(-1), and linearity over a wide range of concentrations for a variety of drugs chosen. It was also determined that the optimum MgCl2 concentration was 1.67 M. This method has shown the applicability of SERS for the detection of trace quantities of benzodiazepines in aqueous solutions as well as the optimization of the technique over a wide range of compounds. This technique can be utilized in the detection of trace benzodiazepines in toxicological samples following extraction of the analyte.

  10. Cultivable bacteria from bulk water, aggregates, and surface sediments of a tidal flat ecosystem

    Science.gov (United States)

    Stevens, Heike; Simon, Meinhard; Brinkhoff, Thorsten

    2009-04-01

    Most-probable-number (MPN) dilution series were used to enumerate and isolate bacteria from bulk water, suspended aggregates, the oxic layer, and the oxic-anoxic transition zone of the sediment of a tidal flat ecosystem in the southern North Sea. The heterotrophic aerobic bacteria were able to grow on agar-agar, alginate, cellulose, chitin, dried and ground Fucus vesiculosus, Marine Broth 2216, palmitate, and starch. MPN counts of bulk water and aggregate samples ranged between 0.18 × 101 and 1.1 × 106 cells per milliliter and those of the sediment surface and the transition zone between 0.8 × 101 and 5.1 × 107 cells per gram dry weight. Marine Broth and F. vesiculosus yielded the highest values of all substrates tested and corresponded to 2.3-32% of 4,6-diamidinophenyl indole cell counts. Strains of seven phylogenetic classes were obtained: Actinobacteria, Bacilli, α- and γ-Proteobacteria, Sphingobacteria, Flavobacteria, and Planctomycetacia. Only with agar-agar as substrate could organisms of all seven classes be isolated.

  11. The cytotoxic activity of amorphous silica nanoparticles is mainly influenced by surface area and not by aggregation.

    Science.gov (United States)

    Rabolli, Virginie; Thomassen, Leen C J; Uwambayinema, Francine; Martens, Johan A; Lison, Dominique

    2011-10-10

    The aggregation state of NP has been a significant source of difficulty for assessing their toxic activity and great efforts have been done to reduce aggregation of and/or to disperse NP in experimental systems. The exact impact of aggregation on toxicity has, however, not been adequately assessed. Here we compared in vitro the cytotoxic activity of stable monodisperse and aggregated silicon-based nanoparticles (SNP) without introducing a dispersing agent that may affect NP properties. SNP aggregates (180 nm) were produced by controlled electrostatic aggregation through addition of KCl to a Ludox SM sol (25 nm) followed by stabilization and extensive dialysis. The size of the preparations was characterized by TEM and DLS; specific surface area and porosity were derived from N(2) sorption measurements. Macrophage (J774) and fibroblast (3T3) cell lines were exposed to monodisperse or aggregate-enriched suspensions of SNP in DMEM in absence of serum. The cytotoxic activity of the different preparations was assessed by the WST1 assay after 24h of exposure. Parameters that determined the cytotoxic activity were traced by comparing the doses of the different preparations that induced half a maximal reduction in WST1 activity (ED(50)) in both cell lines. We found that ED(50) (6-9 μg/ml and 15-22 μg/ml, in J774 and 3T3, respectively) were hardly affected upon aggregation, which was consistent with the fact that the specific surface area of the SNP, a significant determinant of their cytotoxic activity, was unaffected upon aggregation (283-331 m(2)/g). Thus studying small aggregated NP could be as relevant as studying disperse primary NP, when aggregates keep the characteristics of NP, i.e. a high specific surface area and a nanosize dimension. This conclusion does, however, not necessarily hold true for other toxicity endpoints for which the determinants may be different and possibly modified by the aggregation process. Copyright © 2011 Elsevier Ireland Ltd. All rights

  12. DRIFTS study of surface reactivity to NO 2 by zinc nanoparticle aggregates and zinc hollow nanofibers

    Science.gov (United States)

    di Stasio, Stefano; Dal Santo, Vladimiro

    2006-12-01

    Zinc nanostructures synthesized with different morphologies from the same evaporation/condensation technique are studied with concern to surface reactivity to NO 2 by Diffuse Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS). Synthesis of nanopowders is obtained, according to previous work, by gas flow thermal evaporation at 540 °C of bulk Zn grains. Two types of Zn powders are obtained and studied in experiments. The first one is collected on the cold walls of the reactor as a deposit produced by thermophoretic effect. It is constituted by grains (˜10 μm) originated by the stratification of smaller aggregates (˜200 nm) and isolated primary particles (˜50 nm) born in the gas flow. The second type of powder is grown from the condensation of Zn chemical vapors within the expansion orifice of the quartz reactor after relatively long time (˜1 h) deposition process. It is constituted mainly by hollow Zn nanofibers with external and internal diameter about 100 and 60 nm. Preliminary characterization of the two types of powders is made by SEM, TEM, XRD. Thereafter, the two types of samples are studied by DRIFTS at variable temperature (VT). Comparison is made between the home-synthesized nanopowders with respect to commercial Zn standard dust. The Zn hollow nanofibers when exposed to NO 2 are found to exhibit dramatic reactivity, which is not observed at all either in the case of clustered aggregate zinc or of commercial Zn dust powders. Results indicate that, at increasing temperature from RT to 300 °C, the hollow nanofibers surface reacts distinctively with adsorbant gas NO 2, with contemporary formation of a progressively growing narrow absorption band at 2500 cm -1 and contemporary depression of a doublet (˜1600-1628 cm -1) band. In order to justify this striking spectral feature, we propose the occurring of a possible polymerization process at nanofibers surface where most probably as a consequence of pre-treatment and exposure to gas NO 2 a very

  13. Surface microhardness of three thicknesses of mineral trioxide aggregate in different setting conditions.

    Science.gov (United States)

    Shokouhinejad, Noushin; Jafargholizadeh, Leila; Khoshkhounejad, Mehrfam; Nekoofar, Mohammad Hossein; Raoof, Maryam

    2014-11-01

    This study aimed to compare the surface microhardness of mineral trioxide aggregate (MTA) samples having different thicknesses and exposed to human blood from one side and with or without a moist cotton pellet on the other side. Ninety cylindrical molds with three heights of 2, 4, and 6 mm were fabricated. In group 1 (dry condition), molds with heights of 2, 4, and 6 mm (10 molds of each) were filled with ProRoot MTA (Dentsply Tulsa Dental), and the upper surface of the material was not exposed to any additional moisture. In groups 2 and 3, a distilled water- or phosphate-buffered saline (PBS)-moistened cotton pellet was placed on the upper side of MTA, respectively. The lower side of the molds in all the groups was in contact with human blood-wetted foams. After 4 day, the Vickers microhardness of the upper surface of MTA was measured. In the dry condition, the 4 and 6 mm-thick MTA samples showed significantly lower microhardness than the 2 mm-thick samples (p = 0.003 and p = 0.001, respectively). However, when a distilled water- or PBS-moistened cotton pellet was placed over the MTA, no significant difference was found between the surface microhardness of samples having the abovementioned three thicknesses of the material (p = 0.210 and p = 0.112, respectively). It could be concluded that a moist cotton pellet must be placed over the 4 to 6 mm-thick MTA for better hydration of the material. However, this might not be necessary when 2 mm-thick MTA is used.

  14. Surface microhardness of three thicknesses of mineral trioxide aggregate in different setting conditions

    Directory of Open Access Journals (Sweden)

    Noushin Shokouhinejad

    2014-11-01

    Full Text Available Objectives This study aimed to compare the surface microhardness of mineral trioxide aggregate (MTA samples having different thicknesses and exposed to human blood from one side and with or without a moist cotton pellet on the other side. Materials and Methods Ninety cylindrical molds with three heights of 2, 4, and 6 mm were fabricated. In group 1 (dry condition, molds with heights of 2, 4, and 6 mm (10 molds of each were filled with ProRoot MTA (Dentsply Tulsa Dental, and the upper surface of the material was not exposed to any additional moisture. In groups 2 and 3, a distilled water- or phosphate-buffered saline (PBS-moistened cotton pellet was placed on the upper side of MTA, respectively. The lower side of the molds in all the groups was in contact with human blood-wetted foams. After 4 day, the Vickers microhardness of the upper surface of MTA was measured. Results In the dry condition, the 4 and 6 mm-thick MTA samples showed significantly lower microhardness than the 2 mm-thick samples (p = 0.003 and p = 0.001, respectively. However, when a distilled water- or PBS-moistened cotton pellet was placed over the MTA, no significant difference was found between the surface microhardness of samples having the abovementioned three thicknesses of the material (p = 0.210 and p = 0.112, respectively. Conclusions It could be concluded that a moist cotton pellet must be placed over the 4 to 6 mm-thick MTA for better hydration of the material. However, this might not be necessary when 2 mm-thick MTA is used.

  15. Can photoacoustic imaging quantify surface-localized J-aggregating nanoparticles?

    Science.gov (United States)

    Lim, Liang; Mastragostino, Robert; Ng, Kenneth; Zheng, Gang; Wilson, Brian C.

    2017-07-01

    We investigate the feasibility of photoacoustic (PA) imaging to quantify the concentration of surface-localized nanoparticles, using tissue-mimicking phantoms and imaging with a commercial PA instrument at 815 nm and a linear-array transducer at a center frequency of 40 MHz. The nanoparticles were J-aggregating porphysomes (JNP) comprising self-assembling, all-organic porphyrin-lipid micelles with a molar absorption coefficient of 8.7×108 cm-1 M-1 at this wavelength. The PA signal intensity versus JNP areal concentration followed a sigmoidal curve with a reproducible linear range of ˜17 fmol/mm2 to 11 pmol/mm2, i.e., ˜3 orders of magnitude with ±34% error. For physiologically-relevant conditions (i.e., optical scattering-dominated tissues: transport albedo >0.8) and JNP concentrations above ˜330 fmol/mm2, the PA signal depends only on the nanoparticle concentration. Otherwise, independent measurement of the optical absorption and scattering properties of the underlying tissue is required for accurate quantification. The implications for surface PA imaging, such as in the use of targeted nanoparticles applied topically to tissue as in endoscopic diagnosis, are considered.

  16. Erythrocyte Aggregation due to Surface Nanobubble Interactions During the Onset of Thermal Burn Injury

    Science.gov (United States)

    Seidner, Harrison S.

    Red Blood Cell (RBC) aggregation is an important hemorheological phenomenon especially in microcirculation. In healthy individuals, RBCs are known to aggregate and gravitate toward the faster flow in the center of vessels to increase their throughput for more efficient oxygen delivery. Their aggregation is known to occur during a variety of environmental, pathological, and physiological conditions and is reversible when aggregates are subject to the relatively high shear forces in the circulation. The likelihood that aggregates will monodisperse in flow is dependent on the conditions during which they form. In situations where such aggregates are not sheared to monodispersion their presence can impact the perfusion of microvascular networks. More specifically, aggregates subject to the low shear rates in the zone of stasis near regions of thermal burn injury are capable of occluding vessels in the microcirculation and inhibiting the delivery of oxygen and nutrients to tissue downstream. The basic mechanism leading to erythrocyte aggregation at the onset of thermal injury is unknown. This dissertation investigates parameters involved in erythrocyte aggregation, methods of measuring and testing erythrocyte aggregation, and incorporates modeling based on first principles ultimately to propose a mechanism of this phenomenon.

  17. Cell-surface acceleration of urokinase-catalyzed receptor cleavage

    DEFF Research Database (Denmark)

    Høyer-Hansen, G; Ploug, M; Behrendt, N

    1997-01-01

    The urokinase-type plasminogen activator (uPA) binds to a specific cell-surface receptor, uPAR. On several cell types uPAR is present both in the full-length form and a cleaved form, uPAR(2+3), which is devoid of binding activity. The formation of uPAR(2+3) on cultured U937 cells is either direct...

  18. GrlJ, a Dictyostelium GABAB-like receptor with roles in post-aggregation development

    Directory of Open Access Journals (Sweden)

    Anjard Christophe

    2007-05-01

    Full Text Available Abstract Background The G-protein-coupled receptor (GPCR family represents the largest and most important group of targets for chemotherapeutics. They are extremely versatile receptors that transduce signals as diverse as biogenic amines, purins, odorants, ions and pheromones from the extracellular compartment to the interior via biochemical processes involving GTP-binding proteins. Until recently, the cyclic AMP receptors (cARs were the only known G protein coupled receptors in Dictyostelium discoideum. The completed genome sequence revealed the presence of several families of GPCRs in Dictyostelium, among them members of the family 3 of GPCRs, the GABAB/glutamate like receptor family, which in higher eukaryotes is involved in neuronal signaling. Results D. discoideum has seventeen Family 3 members of GPCRs, denoted GrlA through GrlR. Their transcripts are detected throughout development with increased levels during early and late development. We have examined here GrlJ. GFP-tagged GrlJ localises to the plasmamembrane and to internal membranes. Inactivation of the grlJ gene leads to precocious development, and the mutant completes development ~6 hours earlier. Alterations were also noted at the slug stage and in spore formation. grlJ- slugs were longer and broke apart several times on their way to culmination forming smaller but proportionate fruiting bodies. Spores from grlJ- fruiting bodies were malformed and less viable, although the spore differentiation factors were synthesized and sensed normally. Expression of a GFP-tagged full length GrlJ rescued the phenotype. Conclusion Our data suggest that GrlJ acts at several stages of Dictyostelium development and that it is a negative regulator in Dictyostelium development.

  19. Fourier and granulometry methods on 3D images of soil surfaces for evaluating soil aggregate size distribution

    DEFF Research Database (Denmark)

    Jensen, T.; Green, O.; Munkholm, Lars Juhl

    2016-01-01

    The goal of this research is to present and compare two methods for evaluating soil aggregate size distribution based on high resolution 3D images of the soil surface. The methods for analyzing the images are discrete Fourier transform and granulometry. The results of these methods correlate with...

  20. Nonlinear surface dilatational rheology and foaming behavior of protein and protein fibrillar aggregates in the presence of natural surfactant

    NARCIS (Netherlands)

    Wan, Zhili; Yang, Xiaoquan; Sagis, L.M.C.

    2016-01-01

    The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein?surfactant

  1. Measurements on hydrophobic and hydrophilic surfaces using a porous gamma alumina nanoparticle aggregate mounted on Atomic Force Microscopy cantilevers

    NARCIS (Netherlands)

    Das, Theerthankar; Becker, Thomas; Nair, Balagopal N.

    2010-01-01

    Atomic Force Microscopy (AFM) measurements are extensively used for a detailed understanding of molecular and surface forces. In this study, we present a technique for measuring such forces, using an AFM cantilever attached with a porous gamma alumina nanoparticle aggregate. The modified cantilever

  2. Evaluation of 3D laser device for characterizing shape and surface properties of aggregates used in pavements

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2010-08-01

    Full Text Available A new three-dimensional (3D) laser scanning device has been acquired by CSIR Built Environment to determine rock aggregates shape and surface properties. The overall objective is to employ laser-based techniques to accurately determine...

  3. Comparison of a new P2Y12 receptor specific platelet aggregation test with other laboratory methods in stroke patients on clopidogrel monotherapy.

    Directory of Open Access Journals (Sweden)

    Zsuzsa Bagoly

    Full Text Available BACKGROUND: Clinical studies suggest that 10-50% of patients are resistant to clopidogrel therapy. ADP induced platelet aggregation, a widely used test to monitor clopidogrel therapy, is affected by aspirin and is not specific for the P2Y12 receptor inhibited by clopidogrel. OBJECTIVES: To develop a P2Y12-specific platelet aggregation test and to compare it with other methods used for monitoring clopidogrel therapy. PATIENTS/METHODS: Study population included 111 patients with the history of ischemic stroke being on clopidogrel monotherapy and 140 controls. The effect of clopidogrel was tested by a newly developed ADP(PGE1 aggregation test in which prostaglandin E1 treated platelets are used. Results of conventional ADP induced platelet aggregation, VerifyNow P2Y12 assay and ADP(PGE1 aggregation were compared to those obtained by flow cytometric analysis of vasodilator stimulated phosphoprotein (VASP phosphorylation. Reference intervals for all assays were determined according to the guidelines of Clinical Laboratory Standards Institute. RESULTS: The P2Y12-specificity of ADP(PGE1 test was proven by comparing it with ADP aggregation in the presence of P2Y1 antagonist, adenosine 3', 5'-diphosphate. The method was not influenced by aspirin treatment. Approximately 50% of patients were clopidogrel resistant by conventional ADP aggregation and VerifyNow tests. The ADP(PGE1 method and the VASP phosphorylation assay identified 25.9% and 11.7% of patients as non-responders, respectively. ADP(PGE1 aggregation showed good correlation with VASP phosphorylation and had high diagnostic efficiency. CONCLUSION: The new ADP(PGE1 method is a reliable test for monitoring P2Y12 receptor inhibition by platelet aggregation. As a subset of patients are non-responders, monitoring clopidogrel therapy by adequate methods is essential.

  4. Comparison of a New P2Y12 Receptor Specific Platelet Aggregation Test with Other Laboratory Methods in Stroke Patients on Clopidogrel Monotherapy

    Science.gov (United States)

    Bagoly, Zsuzsa; Sarkady, Ferenc; Magyar, Tünde; Kappelmayer, János; Pongrácz, Endre; Csiba, László; Muszbek, László

    2013-01-01

    Background Clinical studies suggest that 10-50% of patients are resistant to clopidogrel therapy. ADP induced platelet aggregation, a widely used test to monitor clopidogrel therapy, is affected by aspirin and is not specific for the P2Y12 receptor inhibited by clopidogrel. Objectives To develop a P2Y12-specific platelet aggregation test and to compare it with other methods used for monitoring clopidogrel therapy. Patients/Methods Study population included 111 patients with the history of ischemic stroke being on clopidogrel monotherapy and 140 controls. The effect of clopidogrel was tested by a newly developed ADP(PGE1) aggregation test in which prostaglandin E1 treated platelets are used. Results of conventional ADP induced platelet aggregation, VerifyNow P2Y12 assay and ADP(PGE1) aggregation were compared to those obtained by flow cytometric analysis of vasodilator stimulated phosphoprotein (VASP) phosphorylation. Reference intervals for all assays were determined according to the guidelines of Clinical Laboratory Standards Institute. Results The P2Y12-specificity of ADP(PGE1) test was proven by comparing it with ADP aggregation in the presence of P2Y1 antagonist, adenosine 3’, 5’-diphosphate. The method was not influenced by aspirin treatment. Approximately 50% of patients were clopidogrel resistant by conventional ADP aggregation and VerifyNow tests. The ADP(PGE1) method and the VASP phosphorylation assay identified 25.9% and 11.7% of patients as non-responders, respectively. ADP(PGE1) aggregation showed good correlation with VASP phosphorylation and had high diagnostic efficiency. Conclusion The new ADP(PGE1) method is a reliable test for monitoring P2Y12 receptor inhibition by platelet aggregation. As a subset of patients are non-responders, monitoring clopidogrel therapy by adequate methods is essential. PMID:23844259

  5. Migration-driven aggregate behaviors of human mesenchymal stem cells on a dendrimer-immobilized surface direct differentiation toward a cardiomyogenic fate commitment.

    Science.gov (United States)

    Ogawa, Yuuki; Kim, Mee-Hae; Kino-Oka, Masahiro

    2016-11-01

    Dynamic behaviors of cell aggregates on a dendrimer surface were investigated to drive the directed differentiation of human mesenchymal stem cells (hMSCs) toward a cardiomyogenic lineage. Cell aggregates on the polyamidoamine dendrimer surface with fifth-generation (G5) of dendron structure showed dynamic changes in morphology associated with repetitive stretching and contracting during migration. Spatial-temporal observations revealed cellular movement in single aggregates by their morphological change through stretching and contracting on the G5 surface, suggesting that the dynamic behavior of aggregate causes mixing of cells. However, aggregates without cell-substrate adhesions on the low-binding culture surface sustained their spherical morphology without cellular movement within a single aggregate. Furthermore, β-catenin was observed at nuclei in aggregates on the G5 surface, and expression of the cardiomyocyte marker cardiac Troponin T (cTnT) was detected. However, β-catenin localized to the nuclei only in the outer region of the aggregate on the low-binding culture surface, and cTnT expression was restricted at the exterior surface of the aggregates. These observations indicate that cell mixing within aggregates on the G5 surface induced the directed differentiation of hMSCs toward a cardiomyogenic lineage by nuclear translocation of β-catenin through dissociation of cell-cell adhesions. These results suggest that migration-driven aggregate behaviors on the dendrimer surface caused repeated morphological changes of aggregate through stretching and contracting, leading to the directed differentiation of hMSCs toward a cardiomyogenic fate commitment. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  6. G-Protein Coupled Receptors: Surface Display and Biosensor Technology

    Science.gov (United States)

    McMurchie, Edward; Leifert, Wayne

    Signal transduction by G-protein coupled receptors (GPCRs) underpins a multitude of physiological processes. Ligand recognition by the receptor leads to the activation of a generic molecular switch involving heterotrimeric G-proteins and guanine nucleotides. With growing interest and commercial investment in GPCRs in areas such as drug targets, orphan receptors, high-throughput screening of drugs and biosensors, greater attention will focus on assay development to allow for miniaturization, ultrahigh-throughput and, eventually, microarray/biochip assay formats that will require nanotechnology-based approaches. Stable, robust, cell-free signaling assemblies comprising receptor and appropriate molecular switching components will form the basis of future GPCR/G-protein platforms, which should be able to be adapted to such applications as microarrays and biosensors. This chapter focuses on cell-free GPCR assay nanotechnologies and describes some molecular biological approaches for the construction of more sophisticated, surface-immobilized, homogeneous, functional GPCR sensors. The latter points should greatly extend the range of applications to which technologies based on GPCRs could be applied.

  7. Deletion of vitamin D receptor leads to premature emphysema/COPD by increased matrix metalloproteinases and lymphoid aggregates formation

    Energy Technology Data Exchange (ETDEWEB)

    Sundar, Isaac K.; Hwang, Jae-Woong [Department of Environmental Medicine, Lung Biology and Disease Program, University of Rochester Medical Center, Box 850, 601 Elmwood Avenue, Rochester, NY 14642 (United States); Wu, Shaoping [Department of Medicine, Gastroenterology and Hepatology Division, University of Rochester Medical Center, Rochester, NY (United States); Sun, Jun [Department of Medicine, Gastroenterology and Hepatology Division, University of Rochester Medical Center, Rochester, NY (United States); The Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY (United States); The James Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY (United States); Rahman, Irfan, E-mail: irfan_rahman@urmc.rochester.edu [Department of Environmental Medicine, Lung Biology and Disease Program, University of Rochester Medical Center, Box 850, 601 Elmwood Avenue, Rochester, NY 14642 (United States)

    2011-03-04

    Research highlights: {yields} Vitamin D deficiency is linked to accelerated decline in lung function. {yields} Levels of vitamin D receptor (VDR) are decreased in lungs of patients with COPD. {yields} VDR knock-out mouse showed increased lung inflammation and emphysema. {yields} This was associated with decline in lung function and increased MMPs. {yields} VDR knock-out mouse model is useful for studying the mechanisms of lung diseases. -- Abstract: Deficiency of vitamin D is associated with accelerated decline in lung function. Vitamin D is a ligand for nuclear hormone vitamin D receptor (VDR), and upon binding it modulates various cellular functions. The level of VDR is reduced in lungs of patients with chronic obstructive pulmonary disease (COPD) which led us to hypothesize that deficiency of VDR leads to significant alterations in lung phenotype that are characteristics of COPD/emphysema associated with increased inflammatory response. We found that VDR knock-out (VDR{sup -/-}) mice had increased influx of inflammatory cells, phospho-acetylation of nuclear factor-kappaB (NF-{kappa}B) associated with increased proinflammatory mediators, and up-regulation of matrix metalloproteinases (MMPs) MMP-2, MMP-9, and MMP-12 in the lung. This was associated with emphysema and decline in lung function associated with lymphoid aggregates formation compared to WT mice. These findings suggest that deficiency of VDR in mouse lung can lead to an early onset of emphysema/COPD because of chronic inflammation, immune dysregulation, and lung destruction.

  8. Flexural strengthening of reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted GFRP bars

    Energy Technology Data Exchange (ETDEWEB)

    Tang, W.C.; Balendran, R.V.; Nadeem, A.; Leung, H.Y. [City University of Hong Kong (China). Department of Building and Construction

    2006-10-15

    Application of near-surface mounted (NSM) fibre reinforced polymer (FRP) bars is emerging as a promising technology for increasing flexural and shear strength of deficient reinforced concrete (RC) members. In order for this technique to perform effectively, the structural behaviour of RC elements strengthened with NSM FRP bars needs to be fully characterized. This paper focuses on the characterization of flexural behaviour of RC members strengthened with NSM glass-FRP bars. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam tests were type of concretes (lightweight polystyrene aggregate concrete and normal concrete), type of reinforcing bars (GFRP and steel), and type of adhesives. Flexural performance of the tested beams including modes of failure, moment-deflection response and ultimate moment capacity are presented and discussed in this paper. Results of this investigation showed that beams with NSM GFRP bars showed a reduction in ultimate deflection and an improvement in flexural stiffness and bending capacity, depending on the PA content of the beams. In general, beams strengthened with NSM GFRP bars overall showed a significant increase in ultimate moment ranging from 23% to 53% over the corresponding beams without NSM GFRP bars. The influence of epoxy type was found conspicuously dominated the moment-deflection response up to the peak moment. Besides, the ultimate moment of concrete beams reinforced with GFRP bars could be predicted satisfactorily using the equation provided in ACI 318-95 Building Code. (author)

  9. The 11S Proteasomal Activator REGγ Impacts Polyglutamine-Expanded Androgen Receptor Aggregation and Motor Neuron Viability through Distinct Mechanisms

    Directory of Open Access Journals (Sweden)

    Jill M. Yersak

    2017-05-01

    Full Text Available Spinal and bulbar muscular atrophy (SBMA is caused by expression of a polyglutamine (polyQ-expanded androgen receptor (AR. The inefficient nuclear proteasomal degradation of the mutant AR results in the formation of nuclear inclusions containing amino-terminal fragments of the mutant AR. PA28γ (also referred to as REGγ is a nuclear 11S-proteasomal activator with limited proteasome activation capabilities compared to its cytoplasmic 11S (PA28α, PA28β counterparts. To clarify the role of REGγ in polyQ-expanded AR metabolism, we carried out genetic and biochemical studies in cell models of SBMA. Overexpression of REGγ in a PC12 cell model of SBMA increased polyQ-expanded AR aggregation and contributed to polyQ-expanded AR toxicity in the presence of dihydrotestosterone (DHT. These effects of REGγ were independent of its association with the proteasome and may be due, in part, to the decreased binding of polyQ-expanded AR by the E3 ubiquitin-ligase MDM2. Unlike its effects in PC12 cells, REGγ overexpression rescued transgenic SBMA motor neurons from DHT-induced toxicity in a proteasome binding-dependent manner, suggesting that the degradation of a specific 11S proteasome substrate or substrates promotes motor neuron viability. One potential substrate that we found to play a role in mutant AR toxicity is the splicing factor SC35. These studies reveal that, depending on the cellular context, two biological roles for REGγ impact cell viability in the face of polyQ-expanded AR; a proteasome binding-independent mechanism directly promotes mutant AR aggregation while a proteasome binding-dependent mechanism promotes cell viability. The balance between these functions likely determines REGγ effects on polyQ-expanded AR-expressing cells.

  10. Phenotypic surface properties (aggregation, adhesion and biofilm formation) and presence of related genes in beneficial vaginal lactobacilli.

    Science.gov (United States)

    Leccese Terraf, M C; Mendoza, L M; Juárez Tomás, M S; Silva, C; Nader-Macías, M E F

    2014-12-01

    To evaluate the phenotypic expression of auto-aggregation, adhesion to mucin and biofilm formation of lactobacilli isolated from human vagina and the presence of related genes. Seven different strains of three Lactobacillus species (Lactobacillus gasseri, Lactobacillus rhamnosus and Lactobacillus reuteri) were evaluated. The auto-aggregation property was determined by spectrophotometric assay and flow cytometry. Adhesion and biofilm formation were assayed by crystal violet staining. The presence of the genes encoding sortases, pilin subunits and surface proteins was evaluated by polymerase chain reactions. The two Lact. reuteri strains assayed showed high auto-aggregation, adhesion to mucin and biofilm formation ability. In these strains, the genes encoding three adhesion proteins were identified. In Lact. rhamnosus CRL (Centro de Referencia para Lactobacilos Culture Collection) 1332, pilus-encoding genes were detected. In all Lact. rhamnosus strains assayed, two genes encoding for other surface proteins related to adhesion and biofilm formation were detected. The vaginal lactobacilli assayed exhibited phenotypic and genetic characteristics that were specific for each strain. This is the first study on auto-aggregation, adhesion and biofilm formation of vaginal Lactobacillus strains by phenotypic and genetic assays. © 2014 The Society for Applied Microbiology.

  11. Aggregate surface areas quantified through laser measurements for South African asphalt mixtures

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2012-02-01

    Full Text Available For several decades, efforts have been made by engineers and researchers in the road and airfield pavements, and railroads to develop methods/procedures for accurate quantification of aggregate shape and packing properties. The difficult part...

  12. Aggregate strength for bituminous surfacings for low volume roads: a heavy vehicle simulator experience

    CSIR Research Space (South Africa)

    Paige-Green, P

    2004-09-01

    Full Text Available This paper discusses an investigation using the CSIR Transportek Heavy Vehicle Simulator (HVS) to determine the impact of using aggregates softer than specified in chip seals and to propose possible relaxations in the currently specified strength...

  13. Protein aggregates stimulate macropinocytosis facilitating their propagation.

    Science.gov (United States)

    Yerbury, Justin J

    2016-03-03

    Temporal and spatial patterns of pathological changes such as loss of neurons and presence of pathological protein aggregates are characteristic of neurodegenerative diseases such as Amyotrophic Lateral Sclerosis, Frontotemporal Dementia, Alzheimer's disease and Parkinson's disease. These patterns are consistent with the propagation of protein misfolding and aggregation reminiscent of the prion diseases. There is a surge of evidence that suggests that large protein aggregates of a range of proteins are able to enter cells via macropinocytosis. Our recent work suggests that this process is activated by the binding of aggregates to the neuron cell surface. The current review considers the potential role of cell surface receptors in the triggering of macropinocytosis by protein aggregates and the possibility of utilizing macropinocytosis pathways as a therapeutic target.

  14. Pharmacological properties of the mouse neurotensin receptor 3. Maintenance of cell surface receptor during internalization of neurotensin.

    Science.gov (United States)

    Navarro, V; Martin, S; Sarret, P; Nielsen, M S; Petersen, C M; Vincent, J; Mazella, J

    2001-04-20

    We recently reported the molecular identification of a new type of receptor for the neuropeptide neurotensin (NT), the neurotensin receptor 3 (NTR3), identical to sortilin, which binds receptor-associated protein. Here, we demonstrate that the cloned mouse NTR3 is expressed on the plasma membrane of transfected COS-7 cells. The mouse NTR3 is detectable by photoaffinity labeling and immunoblotting at the cell surface as a 100 kDa N-glycosylated protein. Biochemical analysis and confocal microscopic imaging clearly indicate that NT is efficiently internalized after binding to NTR3, and that despite this internalization, the amount of receptor present on the cell surface is maintained.

  15. Surface Plasmon Resonance Based Biosensors for Exploring the Influence of Alkaloids on Aggregation of Amyloid-β Peptide

    Directory of Open Access Journals (Sweden)

    Hanna Radecka

    2011-04-01

    Full Text Available The main objective of the presented study was the development of a simple analytical tool for exploring the influence of naturally occurring compounds on the aggregation of amyloid-β peptide (Aβ40 in order to find potential anti-neurodegenerative drugs. The gold discs used for surface plasmon resonance (SPR measurements were modified with thioaliphatic acid. The surface functionalized with carboxylic groups was used for covalent attaching of Aβ40 probe by creation of amide bonds in the presence of EDC/NHS. The modified SPR gold discs were used for exploring the Aβ40 aggregation process in the presence of selected alkaloids: arecoline hydrobromide, pseudopelletierine hydrochloride, trigonelline hydrochloride and α-lobeline hydrochloride. The obtained results were discussed with other parameters which govern the phenomenon studied such as lipophilicity/ hydrophilicy and Aβ40-alkaloid association constants.

  16. Variant size- and glycoforms of the scavenger receptor cysteine-rich protein gp-340 with differential bacterial aggregation

    DEFF Research Database (Denmark)

    Eriksson, Christer; Frängsmyr, Lars; Danielsson Niemi, Liza

    2007-01-01

    glycoforms I and II/III correlate with Se(-) and Se(+) phenotypes, respectively (p Streptococcus suis) or sialic acid- (Streptococcus mutans) binding bacteria......Glycoprotein gp-340 aggregates bacteria in saliva as part of innate defence at mucosal surfaces. We have detected size- and glycoforms of gp-340 between human saliva samples (n = 7) and lung gp-340 from a proteinosis patient using antibodies and lectins in Western blots and ELISA measurements...... bands. Purified I to IV proteins all revealed a N-terminal sequence TGGWIP upon Edman degradation. Moreover, purified gp-340 from the seven donors and lung gp-340 shared N-glycans, sialylated Galbeta1-3GalNAc and (poly)lactosamine structures. However, the larger size gp-340 grouping II/III (n = 4...

  17. Soil aggregate stability and size-selective sediment transport with surface runoff as affected by organic residue amendment.

    Science.gov (United States)

    Shi, Pu; Arter, Christian; Liu, Xingyu; Keller, Martin; Schulin, Rainer

    2017-12-31

    Aggregate breakdown influences the availability of soil particles for size-selective sediment transport with surface runoff during erosive rainfall events. Organic matter management is known to affect aggregate stability against breakdown, but little is known about how this translates into rainfall-induced aggregate fragmentation and sediment transport under field conditions. In this study, we performed field experiments in which artificial rainfall was applied after pre-wetting on three pairs of arable soil plots (1.5×0.75m) six weeks after incorporating a mixture of grass and wheat straw into the topsoil of one plot in each pair (OI treatment) but not on the other plot (NI treatment). Artificial rainfall was applied for approximately 2h on each pair at an intensity of 49.1mmh-1. In both treatments, discharge and sediment concentration in the discharge were correlated and followed a similar temporal pattern after the onset of surface runoff: After a sharp increase at the beginning both approached a steady state. But the onset of runoff was more delayed on the OI plots, and the discharge and sediment concentration were in average only roughly half as high on the OI as on the NI plots. With increasing discharge the fraction of coarse sediment increased. This relationship did not differ between the two treatments. Thus, due to the lower discharge, the fraction of fine particles in the exported sediment was larger in the runoff from the OI plots than from the NI plots. The later runoff onset and lower discharge rate was related to a higher initial aggregate stability on the OI plots. Terrestrial laser scanning proved to be a very valuable method to map changes in the micro-topography of the soil surfaces. It revealed a much less profound decrease in surface roughness on the OI than on the NI plots. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. An assessment of adhesion, aggregation and surface charges of Lactobacillus strains derived from the human oral cavity.

    Science.gov (United States)

    Piwat, S; Sophatha, B; Teanpaisan, R

    2015-07-01

    There is limited information concerning the adhesion and aggregation of human oral lactobacilli. In this study, the adhesion of 10 Lactobacillus species was investigated using H357 oral keratinocyte cells as an in vitro model for oral mucosa. Coaggregation with the representative oral pathogen, Streptococcus mutans ATCC 25175, and the physicochemical cell properties was also evaluated. The results demonstrated significant variations in adhesion (42-96%) and aggregation (autoaggregation, 14-95%; coaggregation, 19-65%). All strains showed a high affinity for chloroform, and most strains had a moderate-to-high hydrophobicity. All strains, except Lactobacillus casei and Lactobacillus gasseri, showed a moderate affinity for ethyl acetate. There was a strong association of autoaggregation with coaggregation (rs = 0·883, P characteristics and aggregation were observed among the Lactobacillus fermentum and Lactobacillus paracasei strains; however, there was a variation in the strains properties within and between species. This study indicated that the Lact. gasseri, Lact. fermentum, and Lact. paracasei strains might be potential probiotics for the human oral cavity given their desirable properties. It should also be emphasized that a selective process for probiotic strains is required. Adhesion to host tissues and bacterial aggregation (auto- and coaggregation) are the highly important criteria for selecting strains with probiotic potential. These abilities are commonly involved with surface-charged characteristics. This is the first study to investigate the oral Lactobacillus species using an oral keratinocyte cell line. Significant results were found for the correlations between the adhesion and surface charge characteristics and for aggregation among certain strains of Lactobacillus gasseri, Lactobacillus fermentum and Lactobacillus paracasei. This observation could be useful when collecting background information for the selection of probiotic strains for use in oral

  19. Superhydrophobic Surfaces with Very Low Hysteresis Prepared by Aggregation of Silica Nanoparticles During In Situ Urea-Formaldehyde Polymerization.

    Science.gov (United States)

    Diwan, Anubhav; Jensen, David S; Gupta, Vipul; Johnson, Brian I; Evans, Delwyn; Telford, Clive; Linford, Matthew R

    2015-12-01

    We present a new method for the preparation of superhydrophobic materials by in situ aggregation of silica nanoparticles on a surface during a urea-formaldehyde (UF) polymerization. This is a one-step process in which a two-tier topography is obtained. The polymerization is carried out for 30, 60, 120, 180, and 240 min on silicon shards. Silicon surfaces are sintered to remove the polymer. SEM and AFM show both an increase in the area covered by the nanoparticles and their aggregation with increasing polymerization time. Chemical vapor deposition of a fluorinated silane in the presence of a basic catalyst gives these surfaces hydrophobicity. Deposition of this low surface energy silane is confirmed by the F 1s signal in XPS. The surfaces show advancing water contact angles in excess of 160 degrees with very low hysteresis (polymerization times for 7 nm and 14 nm silica, respectively. Depositions are successfully demonstrated on glass substrates after they are primed with a UF polymer layer. Superhydrophobic surfaces can also be prepared on unsintered substrates.

  20. Zinc Composite Layers, Incorporating Polymeric Nano-aggregates : Surface Analysis and Electrochemical Behavior

    NARCIS (Netherlands)

    Koleva, D.A.; Zhang, X.; Petrov, P.; Boshkov, N.; Van Breugel, K.; De Wit, J.H.W.; Mol, J.M.C.; Tsvetkova, N.

    2008-01-01

    This study reports on a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers in 5% NaCl solution. The metallic matrix of the ZnC layers incorporates nano-sized, stabilized polymeric aggregates, formed from the amphiphilic tri-block

  1. Feasibility of surface sampling in automated inspection of concrete aggregates during bulk transport on a conveyor

    NARCIS (Netherlands)

    Bakker, M.C.M.; Di Maio, F.; Lotfi, S.; Bakker, M.; Hu, M.; Vahidi, A.

    2017-01-01

    Automated optic inspection of concrete aggregates for pollutants (e.g. wood, plastics, gypsum and brick) is required to establish the suitability for reuse in new concrete products. Inspection is more efficient when directly sampling the materials on the conveyor belt instead of feeding them in a

  2. AGGREGATION AND FUSION OF PLANT-PROTOPLASTS AFTER SURFACE-LABELING WITH BIOTIN AND AVIDIN

    NARCIS (Netherlands)

    VANKESTEREN, WJP; MOLEMA, E; TEMPELAAR, MJ

    1993-01-01

    In mass electrofusion systems with aggregation of protoplasts by alignment, the yield and composition of fusion products can be predicted by a simple model. Through computer simulation, upper limits were found for the yield of binary and multi fusions. To overcome constraints on binary products,

  3. Comparative receptor surface analysis of agonists for tyramine receptor which inhibit sex-pheromone production in Plodia interpunctella.

    Science.gov (United States)

    Hirashima, A; Eiraku, T; Kuwano, E; Eto, M

    2004-03-01

    The quantitative structure-activity relationship (QSAR) of a set of 29 agonists for tyramine (TA) receptor responsible for the inhibition of sex-pheromone production in Plodia interpunctella, was analyzed using comparative receptor surface analysis (CoRSA). Using the common steric and electrostatic features of the most active members of a series of compounds, CoRSA generated a virtual receptor model, represented as points on a surface complementary to the van der Waals or Wyvill steric surface of the aligned compounds. Three-dimensional energetics descriptors were calculated from receptor surface model (RSM)/ligand interaction and these three-dimensional descriptors were used in genetic partial least squares data analysis to generate a QSAR model, giving a 3D QSAR with r(2)=0.969 for calibration and CV- r(2)=0.635 for the leave-one-out cross validation.

  4. Synaptic abnormalities and cytoplasmic glutamate receptor aggregates in contactin associated protein-like 2/Caspr2 knockout neurons.

    Science.gov (United States)

    Varea, Olga; Martin-de-Saavedra, Maria Dolores; Kopeikina, Katherine J; Schürmann, Britta; Fleming, Hunter J; Fawcett-Patel, Jessica M; Bach, Anthony; Jang, Seil; Peles, Elior; Kim, Eunjoon; Penzes, Peter

    2015-05-12

    Central glutamatergic synapses and the molecular pathways that control them are emerging as common substrates in the pathogenesis of mental disorders. Genetic variation in the contactin associated protein-like 2 (CNTNAP2) gene, including copy number variations, exon deletions, truncations, single nucleotide variants, and polymorphisms have been associated with intellectual disability, epilepsy, schizophrenia, language disorders, and autism. CNTNAP2, encoded by Cntnap2, is required for dendritic spine development and its absence causes disease-related phenotypes in mice. However, the mechanisms whereby CNTNAP2 regulates glutamatergic synapses are not known, and cellular phenotypes have not been investigated in Cntnap2 knockout neurons. Here we show that CNTNAP2 is present in dendritic spines, as well as axons and soma. Structured illumination superresolution microscopy reveals closer proximity to excitatory, rather than inhibitory synaptic markers. CNTNAP2 does not promote the formation of synapses and cultured neurons from Cntnap2 knockout mice do not show early defects in axon and dendrite outgrowth, suggesting that CNTNAP2 is not required at this stage. However, mature neurons from knockout mice show reduced spine density and levels of GluA1 subunits of AMPA receptors in spines. Unexpectedly, knockout neurons show large cytoplasmic aggregates of GluA1. Here we characterize, for the first time to our knowledge, synaptic phenotypes in Cntnap2 knockout neurons and reveal a novel role for CNTNAP2 in GluA1 trafficking. Taken together, our findings provide insight into the biological roles of CNTNAP2 and into the pathogenesis of CNTNAP2-associated neuropsychiatric disorders.

  5. cAMP-Induced Desensitization of Surface cAMP Receptors in Dictyostelium : Different Second Messengers Mediate Receptor Phosphorylation, Loss of Ligand Binding, Degradation of Receptor, and Reduction of Receptor mRNA Levels

    NARCIS (Netherlands)

    Haastert, Peter J.M. van; Wang, Mei; Bominaar, Anthony A.; Devreotes, Peter N.; Schaap, Pauline

    Surface cAMP receptors on Dictyostelium cells are linked to several second messenger systems and mediate multiple physiological responses, including chemotaxis and differentiation. Activation of the receptor also triggers events which desensitize signal transduction. These events include the

  6. N₂-BET is a Proxy for Primary Particle Size and May Not Be Representative of Available Specific Surface Area for Aggregated Nanoparticle Aerosols.

    Science.gov (United States)

    Edinger, Steven R; Gernand, Jeremy M

    2018-05-01

    The knowledge of the specific surface area of aerosolized engineered nanoparticles could be important for mechanistically understanding their toxic potential or functional characteristics. The most widely method to perform this measurement, N2-BET, however, may not accurately represent the available surface area for hetero-aggregated nanoparticles in the context of large biological molecules. This study conducted an analysis of published characterization measurements including primary particle size, aggregation state, and specific surface area made for dry aerosolized nanoparticles. Results indicate that primary particle size explains 65% of the variance in specific surface area, while aggregation (as measured by mass median aerodynamic diameter) only explains 20% of the variance. Curiously, increasing aggregation (larger MMAD) is associated with increasing SSA as measured by N2-BET, likely an artifact of the measurement method, which suggests that this technique may not be appropriate for studies investigating biological interactions with nanoparticles.

  7. Synthesis, surface modification and biological imaging of aggregation-induced emission (AIE) dye doped silica nanoparticles

    Science.gov (United States)

    Mao, Liucheng; Liu, Meiying; Xu, Dazhuang; Wan, Qing; Huang, Qiang; Jiang, Ruming; Shi, Yingge; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2017-05-01

    Fluorescent silica nanoparticles (FSNPs) have been extensively investigated for various biomedical applications in recently years. However, the aggregation of organic dyes in silica nanoparticles also leads the significant fluorescence quenching owing to the aggregation caused quenching effects of organic dyes. Herein, we developed a rather facile strategy to fabricate FSNPs with desirable fluorescent properties through non-covalent incorporation of fluorophores with aggregation-induced emission (AIE) feature into silica nanoparticles, which were subsequently modified with functional polymers. The resultant FSNPs polymer nanocomposites (named as FSNPs-poly(IA-co-PEGMA)) exhibited uniform spherical morphology, high water dispersiity, and bright red fluorescence. Cytotoxicity results indicate that FSNPs-poly(IA-co-PEGMA) possess excellent biocompatibility. Cell uptake behavior suggests FSNPs-poly(IA-co-PEGMA) are of great potential for biological imaging applications. Taken together, we have reported a facile method for the fabrication of FSNPs through non-covalent encapsulation using an AIE-active dye. These FSNPs can be further functionalized with functional polymers through ring-opening reaction and the resultant FSNPs-poly(IA-co-PEGMA) showed great potential for biological imaging. More importantly, we believe that many other functional components could also be integrated into these FSNPs through the facile ring-opening reaction. Therefore, this method should be a facile and general tool for fabrication of polymer functionalized AIE-active FSNPs.

  8. Cell Surface Binding and Internalization of Aβ Modulated by Degree of Aggregation

    Directory of Open Access Journals (Sweden)

    David A. Bateman

    2011-01-01

    Full Text Available The amyloid peptides, Aβ40 and Aβ42, are generated through endoproteolytic cleavage of the amyloid precursor protein. Here we have developed a model to investigate the interaction of living cells with various forms of aggregated Aβ40/42. After incubation at endosomal pH 6, we observed a variety of Aβ conformations after 3 (Aβ3, 24 (Aβ24, and 90 hours (Aβ90. Both Aβ4224 and Aβ4024 were observed to rapidly bind and internalize into differentiated PC12 cells, leading to accumulation in the lysosome. In contrast, Aβ40/4290 were both found to only weakly associate with cells, but were observed as the most aggregated using dynamic light scattering and thioflavin-T. Internalization of Aβ40/4224 was inhibited with treatment of monodansylcadaverine, an endocytosis inhibitor. These studies indicate that the ability of Aβ40/42 to bind and internalize into living cells increases with degree of aggregation until it reaches a maximum beyond which its ability to interact with cells diminishes drastically.

  9. Expression of surface platelet receptors (CD62P and CD41/61) in horses with recurrent airway obstruction (RAO).

    Science.gov (United States)

    Iwaszko-Simonik, Alicja; Niedzwiedz, Artur; Graczyk, Stanislaw; Slowikowska, Malwina; Pliszczak-Krol, Aleksandra

    2015-03-15

    Recurrent airway obstruction (RAO) is an allergic disease of horses similar to human asthma, which is characterized by airway inflammation and activation of neutrophils, lymphocytes and platelets. Platelet activation and an increase in circulating platelet-leukocyte aggregates may lead to airway remodeling. The aim of this study was to investigate platelet status in RAO-affected horses based on the platelet morphology and platelet surface expression of CD41/61 and CD62P. Ten RAO-affected horses and ten healthy horses were included in this study. Blood samples were obtained to determine the platelet count (PLT), mean platelet volume (MPV) and platelet large cell ratio (P-LCR). Expression of CD62P and CD41/61 was detected by flow cytometry on activated platelets. The median PLT was significantly reduced in horses with RAO compared to the controls. The MPV and the P-LCR values were significantly higher in RAO horses than controls. Expression of CD41/61 on platelets was increased in RAO horses, while CD62P expression was reduced. This study demonstrated the morphological changes in platelets and expression of platelet surface receptors. Despite the decrease of CD62P expression, the observed increased surface expression of CD41/61 on platelets in horses with RAO may contribute to the formation of platelet aggregates in their respiratory system. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. CSF-1 receptor signalling is governed by pre-requisite EHD1 mediated receptor display on the macrophage cell surface.

    Science.gov (United States)

    Cypher, Luke R; Bielecki, Timothy Alan; Huang, Lu; An, Wei; Iseka, Fany; Tom, Eric; Storck, Matthew D; Hoppe, Adam D; Band, Vimla; Band, Hamid

    2016-09-01

    Colony stimulating factor-1 receptor (CSF-1R), a receptor tyrosine kinase (RTK), is the master regulator of macrophage biology. CSF-1 can bind CSF-1R resulting in receptor activation and signalling essential for macrophage functions such as proliferation, differentiation, survival, polarization, phagocytosis, cytokine secretion, and motility. CSF-1R activation can only occur after the receptor is presented on the macrophage cell surface. This process is reliant upon the underlying macrophage receptor trafficking machinery. However, the mechanistic details governing this process are incompletely understood. C-terminal Eps15 Homology Domain-containing (EHD) proteins have recently emerged as key regulators of receptor trafficking but have not yet been studied in the context of macrophage CSF-1R signalling. In this manuscript, we utilize primary bone-marrow derived macrophages (BMDMs) to reveal a novel function of EHD1 as a regulator of CSF-1R abundance on the cell surface. We report that EHD1-knockout (EHD1-KO) macrophages cell surface and total CSF-1R levels are significantly decreased. The decline in CSF-1R levels corresponds with reduced downstream macrophage functions such as cell proliferation, migration, and spreading. In EHD1-KO macrophages, transport of newly synthesized CSF-1R to the macrophage cell surface was reduced and was associated with the shunting of the receptor to the lysosome, which resulted in receptor degradation. These findings reveal a novel and functionally important role for EHD1 in governing CSF-1R signalling via regulation of anterograde transport of CSF-1R to the macrophage cell surface. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Spatial aggregation of land surface characteristics : impact of resolution of remote sensing data on land surface modelling

    NARCIS (Netherlands)

    Pelgrum, H.

    2000-01-01

    Land surface models describe the exchange of heat, moisture and momentum between the land surface and the atmosphere. These models can be solved regionally using remote sensing measurements as input. Input variables which can be derived from remote sensing measurements are surface albedo,

  12. Surface-coating-dependent dissolution, aggregation, and reactive oxygen species (ROS) generation of silver nanoparticles under different irradiation conditions.

    Science.gov (United States)

    Li, Yang; Zhang, Wen; Niu, Junfeng; Chen, Yongsheng

    2013-09-17

    Dissolution, aggregation, and reactive oxygen species (ROS) generation are three major processes that silver nanoparticles (AgNPs) undergo in aqueous environments. In this study, the effects of AgNP surface coatings on these three processes were systematically evaluated under three irradiation conditions (UV-365, UV-254, and xenon lamp) to advance knowledge on the environmental fate and photochemical kinetics of AgNPs. The AgNPs used were (a) bare-AgNPs, (b) electrostatically stabilized citrate-AgNPs, and (c) sterically stabilized polyvinylpyrrolidone-AgNPs (PVP-AgNPs), and the light exposures greatly promoted the three processes. Both the 5-h released Ag(+) concentrations and the 2.5-h aggregation rate followed the order UV-365 > xenon lamp > UV-254 for all three types of AgNPs. For all irradiation conditions, the 5-h released Ag(+) concentration was highest for bare-AgNPs, followed by PVP-AgNPs and citrate-AgNPs; the 2.5-h aggregation rate was highest for bare-AgNPs, followed by citrate-AgNPs and PVP-AgNPs, which indicated that surface coating significantly determines the process kinetics of AgNPs. Under UV-365 irradiation, the bare-AgNPs generated superoxide and hydroxyl radicals, but the citrate-AgNPs yielded only superoxide radical, and the PVP-AgNPs did not generate any ROS. This study highlights the different fates and kinetic behaviors of AgNPs during photochemical interactions, providing important insight into the environmental implications of AgNP release.

  13. Remote spectral identification of surface aggregates by thermal imaging techniques - Progress report

    Science.gov (United States)

    Scholen, Douglas E.; Clerke, William H.; Burns, Gregory S.

    1991-01-01

    The NASA Thermal Infrared Multispectral Scanner (TIMS) has been successfully used for the remote identification of a variety of soil and aggregate deposits in vegetated areas of two states. Over three million cubic meters of gravel deposits were identified from the imagery during a two year period. Verification was accomplished by ground reconnaissance using drilling machinery and by ground instrumentation. The method has been used to differentiate between fine and coarse grained soils, and gravel deposits. The deposits were found to have been naturally sorted according to grain size by depositional processes, providing each deposit with distinct spectral qualities. It was found that the masking effects of relatively dense vegetation were largely overcome by using imagery acquired at higher altitudes above terrain than 9000 meters, due to loss of resolution of the finer detail. The mechanics of image resolution are discussed, a method of data analysis used is described, and sample spectral signatures are illustrated.

  14. Generalized paired-agent kinetic model for in vivo quantification of cancer cell-surface receptors under receptor saturation conditions

    Science.gov (United States)

    Sadeghipour, N.; Davis, S. C.; Tichauer, K. M.

    2017-01-01

    New precision medicine drugs oftentimes act through binding to specific cell-surface cancer receptors, and thus their efficacy is highly dependent on the availability of those receptors and the receptor concentration per cell. Paired-agent molecular imaging can provide quantitative information on receptor status in vivo, especially in tumor tissue; however, to date, published approaches to paired-agent quantitative imaging require that only ‘trace’ levels of imaging agent exist compared to receptor concentration. This strict requirement may limit applicability, particularly in drug binding studies, which seek to report on a biological effect in response to saturating receptors with a drug moiety. To extend the regime over which paired-agent imaging may be used, this work presents a generalized simplified reference tissue model (GSRTM) for paired-agent imaging developed to approximate receptor concentration in both non-receptor-saturated and receptor-saturated conditions. Extensive simulation studies show that tumor receptor concentration estimates recovered using the GSRTM are more accurate in receptor-saturation conditions than the standard simple reference tissue model (SRTM) (% error (mean  ±  sd): GSRTM 0  ±  1 and SRTM 50  ±  1) and match the SRTM accuracy in non-saturated conditions (% error (mean  ±  sd): GSRTM 5  ±  5 and SRTM 0  ±  5). To further test the approach, GSRTM-estimated receptor concentration was compared to SRTM-estimated values extracted from tumor xenograft in vivo mouse model data. The GSRTM estimates were observed to deviate from the SRTM in tumors with low receptor saturation (which are likely in a saturated regime). Finally, a general ‘rule-of-thumb’ algorithm is presented to estimate the expected level of receptor saturation that would be achieved in a given tissue provided dose and pharmacokinetic information about the drug or imaging agent being used, and physiological

  15. Analysis and modification of defective surface aggregates on PCDTBT:PCBM solar cell blends using combined Kelvin probe, conductive and bimodal atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Hanaul Noh

    2017-03-01

    Full Text Available Organic photovoltaic systems comprising donor polymers and acceptor fullerene derivatives are attractive for inexpensive energy harvesting. Extensive research on polymer solar cells has provided insight into the factors governing device-level efficiency and stability. However, the detailed investigation of nanoscale structures is still challenging. Here we demonstrate the analysis and modification of unidentified surface aggregates. The aggregates are characterized electrically by Kelvin probe force microscopy and conductive atomic force microscopy (C-AFM, whereby the correlation between local electrical potential and current confirms a defective charge transport. Bimodal AFM modification confirms that the aggregates exist on top of the solar cell structure, and is used to remove them and to reveal the underlying active layer. The systematic analysis of the surface aggregates suggests that the structure consists of PCBM molecules.

  16. Antibody-protein A conjugated quantum dots for multiplexed imaging of surface receptors in living cells.

    Science.gov (United States)

    Jin, Takashi; Tiwari, Dhermendra K; Tanaka, Shin-Ichi; Inouye, Yasushi; Yoshizawa, Keiko; Watanabe, Tomonobu M

    2010-11-01

    To use quantum dots (QDs) as fluorescent probes for receptor imaging, QD surface should be modified with biomolecules such as antibodies, peptides, carbohydrates, and small-molecule ligands for receptors. Among these QDs, antibody conjugated QDs are the most promising fluorescent probes. There are many kinds of coupling reactions that can be used for preparing antibody conjugated QDs. Most of the antibody coupling reactions, however, are non-selective and time-consuming. In this paper, we report a facile method for preparing antibody conjugated QDs for surface receptor imaging. We used ProteinA as an adaptor protein for binding of antibody to QDs. By using ProteinA conjugated QDs, various types of antibodies are easily attached to the surface of the QDs via non-covalent binding between the F(c) (fragment crystallization) region of antibody and ProteinA. To show the utility of ProteinA conjugated QDs, HER2 (anti-human epidermal growth factor receptor 2) in KPL-4 human breast cancer cells were stained by using anti-HER2 antibody conjugated ProteinA-QDs. In addition, multiplexed imaging of HER2 and CXCR4 (chemokine receptor) in the KPL-4 cells was performed. The result showed that CXCR4 receptors coexist with HER2 receptors in the membrane surface of KPL-4 cells. ProteinA mediated antibody conjugation to QDs is very useful to prepare fluorescent probes for multiplexed imaging of surface receptors in living cells.

  17. Effect of Blood Contamination on Marginal Adaptation and Surface Microstructure of Mineral Trioxide Aggregate: A SEM Study

    Science.gov (United States)

    Salem Milani, Amin; Rahimi, Saeed; Froughreyhani, Mohammad; Vahid Pakdel, Mahdi

    2013-01-01

    Background and aims In various clinical situations, mineral trioxide aggregate (MTA) may come into direct contact or even be mixed with blood. The aim of the present study was to evaluate the effect of exposure to blood on marginal adaptation and surface microstructure of MTA. Materials and methods Thirty extracted human single-rooted teeth were used. Standard root canal treatment was carried out. Root-ends were resected, and retrocavities were prepared. The teeth were randomly divided into two groups (n = 15): in group 1, the internal surface of the cavities was coated with fresh blood. Then, the cavities were filled with MTA. The roots were immersed in molds containing fresh blood. In group 2, the aforementioned procedures were performed except that synthetic tissue fluid (STF) was used instead of blood. To assess the marginal adaptation, “gap perimeter” and “maximum gap width” were measured under scanning electron microscope. The surface microstructure was also examined. Independent samples t-test and Mann-Whitney U test were used to analyze the data. Results Maximum gap width and gap perimeter in the blood-exposed group were significantly larger than those in the STF-exposed group (p MTA, and blood-exposed MTA has a different surface microstructure compared to STF-exposed MTA. PMID:24082987

  18. Characterization of aggregates of surface modified fullerenes by asymmetrical flow field-flow fractionation with multi angle light scattering detection

    NARCIS (Netherlands)

    Astefanei, A.; Kok, W.T.; Bäuerlein, P.; Núñez, O.; Galceran, M.T.; de Voogt, P.; Schoenmakers, P.J.

    2015-01-01

    Fullerenes are carbon nanoparticles with widespread biomedical, commercial and industrial applications. Attributes such as their tendency to aggregate and aggregate size and shape impact their ability to be transported into and through the environment and living tissues. Knowledge of these

  19. Wellcome Prize Lecture. Cell surface, ion-sensing receptors.

    Science.gov (United States)

    Riccardi, Daniela

    2002-07-01

    Changes in extracellular calcium (Ca(2+)o) concentration ([Ca2+]o) affect kidney function both under basal and hormone-stimulated conditions. The molecular identification of an extracellular Ca(2+)-sensing receptor (CaR) has confirmed a direct role of Ca(2+)o on parathyroid and kidney function (i.e. independent of calciotropic hormones) as a modulator of Ca2+ homeostasis. In addition, evidence accumulated over the last 10 years has shown that CaR is also expressed in regions outside the calcium homeostatic system where its role is largely undefined but seems to be linked to regulation of local ionic homeostasis. The parathyroid and kidney CaRs are 1081 and 1079 amino acids long, respectively, and belong to the type III family of G protein-coupled receptors (GPCRs), which includes other CaRs, metabotropic glutamate receptors and putative vomeronasal organ receptors. For the CaR, its low (millimolar) affinity for Ca2+, its positive cooperativity and its large ion-sensing extracellular domain, indicate that the receptor is more sensitive to changes in net cationic charge rather than to a specific ligand. Mg2+, trivalent cations of the lanthanide series and polyvalent cations such as spermine and aminoglycoside antibiotics can all activate the receptor in vitro with EC50 values in the micromolar range for trivalent and polyvalent cations or in the millimolar range for Ca2+ and Mg2+. In addition to true CaR agonists, CaR sensitivity to Ca(2+)o is also susceptible to allosteric modulation by ionic strength, L-amino acids and by pharmacological agents. This review will address endogenous and exogenous CaR agonists, the role of the receptor in the calcium homeostatic system and some speculation on possible role(s) of the CaR in regions not involved in mineral ion homeostasis.

  20. Priming by chemokines restricts lateral mobility of the adhesion receptor LFA-1 and restores adhesion to ICAM-1 nano-aggregates on human mature dendritic cells.

    Directory of Open Access Journals (Sweden)

    Kyra J E Borgman

    Full Text Available LFA-1 is a leukocyte specific β2 integrin that plays a major role in regulating adhesion and migration of different immune cells. Recent data suggest that LFA-1 on mature dendritic cells (mDCs may function as a chemokine-inducible anchor during homing of DCs through the afferent lymphatics into the lymph nodes, by transiently switching its molecular conformational state. However, the role of LFA-1 mobility in this process is not yet known, despite that the importance of lateral organization and dynamics for LFA-1-mediated adhesion regulation is broadly recognized. Using single particle tracking approaches we here show that LFA-1 exhibits higher mobility on resting mDCs compared to monocytes. Lymphoid chemokine CCL21 stimulation of the LFA-1 high affinity state on mDCs, led to a significant reduction of mobility and an increase on the fraction of stationary receptors, consistent with re-activation of the receptor. Addition of soluble monomeric ICAM-1 in the presence of CCL21 did not alter the diffusion profile of LFA-1 while soluble ICAM-1 nano-aggregates in the presence of CCL21 further reduced LFA-1 mobility and readily bound to the receptor. Overall, our results emphasize the importance of LFA-1 lateral mobility across the membrane on the regulation of integrin activation and its function as adhesion receptor. Importantly, our data show that chemokines alone are not sufficient to trigger the high affinity state of the integrin based on the strict definition that affinity refers to the adhesion capacity of a single receptor to its ligand in solution. Instead our data indicate that nanoclustering of the receptor, induced by multi-ligand binding, is required to maintain stable cell adhesion once LFA-1 high affinity state is transiently triggered by inside-out signals.

  1. Priming by chemokines restricts lateral mobility of the adhesion receptor LFA-1 and restores adhesion to ICAM-1 nano-aggregates on human mature dendritic cells.

    Science.gov (United States)

    Borgman, Kyra J E; van Zanten, Thomas S; Manzo, Carlo; Cabezón, Raquel; Cambi, Alessandra; Benítez-Ribas, Daniel; Garcia-Parajo, Maria F

    2014-01-01

    LFA-1 is a leukocyte specific β2 integrin that plays a major role in regulating adhesion and migration of different immune cells. Recent data suggest that LFA-1 on mature dendritic cells (mDCs) may function as a chemokine-inducible anchor during homing of DCs through the afferent lymphatics into the lymph nodes, by transiently switching its molecular conformational state. However, the role of LFA-1 mobility in this process is not yet known, despite that the importance of lateral organization and dynamics for LFA-1-mediated adhesion regulation is broadly recognized. Using single particle tracking approaches we here show that LFA-1 exhibits higher mobility on resting mDCs compared to monocytes. Lymphoid chemokine CCL21 stimulation of the LFA-1 high affinity state on mDCs, led to a significant reduction of mobility and an increase on the fraction of stationary receptors, consistent with re-activation of the receptor. Addition of soluble monomeric ICAM-1 in the presence of CCL21 did not alter the diffusion profile of LFA-1 while soluble ICAM-1 nano-aggregates in the presence of CCL21 further reduced LFA-1 mobility and readily bound to the receptor. Overall, our results emphasize the importance of LFA-1 lateral mobility across the membrane on the regulation of integrin activation and its function as adhesion receptor. Importantly, our data show that chemokines alone are not sufficient to trigger the high affinity state of the integrin based on the strict definition that affinity refers to the adhesion capacity of a single receptor to its ligand in solution. Instead our data indicate that nanoclustering of the receptor, induced by multi-ligand binding, is required to maintain stable cell adhesion once LFA-1 high affinity state is transiently triggered by inside-out signals.

  2. Identification of insulin in the tear film and insulin receptor and IGF-1 receptor on the human ocular surface.

    Science.gov (United States)

    Rocha, Eduardo M; Cunha, Daniel A; Carneiro, Everardo M; Boschero, Antonio C; Saad, Mário J A; Velloso, Lício A

    2002-04-01

    Insulin produces pleiotropic effects on sensitive tissues, including the ocular surface, through the tyrosine kinase insulin receptor. Cerebrospinal fluid and secreted fluids, such as milk and saliva, have been reported to contain insulin. In the present study, the presence of insulin was examined in tear film, and the expression of insulin and insulin-like growth factor (IGF)-1 receptor was examined in the human cornea and conjunctiva. Stimulated tear samples collected from 33 volunteers (17 men, 16 women), aged 23 to 51 years, who were fed or fasted for 12 hours, were assayed for total protein and insulin content by the biuret dye test and a radioimmunoassay, respectively. Frozen sections of human cornea (n = 4) and conjunctiva (n = 3) were incubated with anti-insulin receptor and anti-IGF-1 receptor antibodies and developed with a secondary antibody-peroxidase conjugate. Insulin was detected in all tear samples analyzed, the mean concentration being 0.404 +/- 0.129 ng/mL. There were no gender-related differences. In fed subjects, tears tended toward a higher insulin content than those in fasted individuals. There was no linear correlation between insulin and total protein content (mean, 4.61 +/- 0.79 mg/mL) in the tear film. Insulin and IGF-1 receptors were detected in the plasma membrane and cytoplasm of corneal and conjunctival epithelial cells. To the best of the authors' knowledge, this study represents the first demonstration of insulin in human tear film and the presence of insulin and IGF-1 receptor on the human ocular surface. These results suggest that the pancreatic hormone may play a metabolic and/or mitogenic role on the ocular surface.

  3. Effects of Added Salts on Surface Tension and Aggregation of Crown Ether Surfactants.

    Science.gov (United States)

    Suzuki, Maki; Fujio, Katsuhiko

    2016-01-01

    Two crown ether surfactants, dodecanoyloxymethyl- (C11Φ6) and octanoyloxymethyl-18-crown-6 (C7Φ6), were synthesized and the surface tension dependence on surfactant concentration of their aqueous solutions was measured both in the absence and presence of alkali chlorides to confirm the critical micelle concentration (CMC) is highest for the added cation that have an ionic diameter comparable to the hole size of the crown ether ring and that several break points on the surface tension vs. concentration curves occur for these crown ether surfactants. For C11Φ6 and C7Φ6, in the absence of salt, the surface tension vs. concentration curves had two break points. Using the solubilization of a water-insoluble dye as an indicator, we found that the break point at the higher concentration (m0) for C7Φ6 was due to micelle formation. Two break points were also observed for the aqueous solution of C11Φ6 in the presence of NaCl, KCl, RbCl, and CsCl salts at concentrations of 0.22 mol kg(-1) and for C7Φ6 with 0.22 mol kg(-1) KCl added. The CMC (m0) was found to be the highest for solutions containing K(+) salts because K(+) has an ionic diameter comparable to the hole size of 18-crown-6 ring. Furthermore, the CMC decreased as the ionic diameters of the added cations deviated from the hole size. The molecular areas at two break points, estimated by the Gibbs adsorption isotherm, except for that at the break point at mI of C7Φ6, were very small for an adsorbed monolayer. Further investigation is required to elucidate the reason for the break point at mI.

  4. Insights into cellular signalling by G protein coupled receptor transactivation of cell surface protein kinase receptors.

    Science.gov (United States)

    Chaplin, Rebecca; Thach, Lyna; Hollenberg, Morley D; Cao, Yingnan; Little, Peter J; Kamato, Danielle

    2017-06-01

    G protein coupled receptor (GPCR) signalling is mediated by transactivation independent and transactivation dependent pathways. GPCRs transactivate protein tyrosine kinase receptors (PTKRs) and protein serine/threonine kinase receptors (PS/TKR). Since the initial observations of transactivation dependent signalling, there has been an effort to understand the mechanisms behind this phenomena. GPCR signalling has evolved to include biased signalling. Biased signalling, whereby selected ligands can activate the same GPCR that can generate multiple signals, but drive only a unique response. To date, there has been no focus on the ability of biased agonists to activate the PTKR and PS/TKR transactivation pathways differentially. As such, this represents a novel direction for future research. This review will discuss the main mechanisms of GPCR mediated receptor transactivation and the pathways involved in intracellular responses.

  5. Effect of Blood Contamination on Marginal Adaptation and Surface Microstructure of Mineral Trioxide Aggregate: A SEM Study

    Directory of Open Access Journals (Sweden)

    Amin Salem Milani

    2013-08-01

    Full Text Available Background and aims. In various clinical situations, mineral trioxide aggregate (MTA may come into direct contact or even be mixed with blood. The aim of the present study was to evaluate the effect of exposure to blood on marginal adaptation and surface microstructure of MTA. Materials and methods. Thirty extracted human single-rooted teeth were used. Standard root canal treatment was carried out. Root-ends were resected, and retrocavities were prepared. The teeth were randomly divided into two groups (n = 15: in group 1, the internal surface of the cavities was coated with fresh blood. Then, the cavities were filled with MTA. The roots were immersed in molds containing fresh blood. In group 2, the aforementioned procedures were performed except that synthetic tissue fluid (STF was used instead of blood. To assess the marginal adaptation, “gap perimeter” and “maximum gap width” were measured under scanning electron microscope. The surface microstructure was also examined. Independent samples t-test and Mann-Whitney U test were used to analyze the data. Results. Maximum gap width and gap perimeter in the blood-exposed group were significantly larger than those in the STF-exposed group (p < 0.01. In the blood-exposed group, the crystals tended to be more rounded and less angular compared with the STF-exposed group, and there was a general lack of needle-like crystals. Conclusion. Exposure to blood during setting has a negative effect on marginal adaptation of MTA, and blood-exposed MTA has a different surface microstructure compared to STF-exposed MTA.

  6. Confined laminar flow on a super-hydrophobic surface drives the initial stages of tau protein aggregation

    KAUST Repository

    Moretti, Manola

    2018-02-01

    Super-hydrophobic micro-patterned surfaces are ideal substrates for the controlled self-assembly and substrate-free characterization of biological molecules. In this device, the tailored surface supports a micro-volume drop containing the molecules of interest. While the quasi-spherical drop is evaporating under controlled conditions, its de-wetting direction is guided by the pillared microstructure on top of the device, leading to the formation of threads between the neighboring pillars. This effect has been exploited here to elucidate the mechanism triggering the formation of amyloid fibers and oligomers in tau related neurodegenerative diseases. By using Raman spectroscopy, we demonstrate that the fiber bridging the pillars contains β-sheets, a characteristic feature of amyloid aggregation. We propose that the combination of laminar flow, shear stress and molecular crowding taking place while the drop is evaporating on the SHMS, induces the reorganization of the tau protein secondary structure and we suggest that this effect could in fact closely mimic the actual mechanism occurring in the human brain environment. Such a straightforward technique opens up new possibilities in the field of self-assembly of biomolecules and their characterization by different methods (SEM, AFM, Raman spectroscopy, TEM), in a single device.

  7. RORγt, a multitask nuclear receptor at mucosal surfaces.

    Science.gov (United States)

    Eberl, G

    2017-01-01

    RORγt is a nuclear hormone receptor that has followed an exponential success carrier. Its modest origins as an orphan receptor cloned from human pancreas blossomed within 15 years into a critical regulator of anti-microbial immunity and a major target in the fight against inflammatory pathologies. Here, I review its role as a transcription factor required for the generation of type 3 lymphoid cells, which induce the development of lymphoid tissues, provide resistance of epithelial stem cells to injury, maintain homeostasis with the symbiotic microbiota, orchestrate defense against extracellular microbes, and regulate allergic responses. RORγt is also an intriguing molecule that is regulated by the circadian rhythm and includes cholesterol metabolites as ligands. RORγt therefore links anti-microbial immunity with circadian rhythms and steroids, the logic of which remains to be understood.

  8. Evidence for leptin receptor isoforms heteromerization at the cell surface.

    Science.gov (United States)

    Bacart, Johan; Leloire, Audrey; Levoye, Angélique; Froguel, Philippe; Jockers, Ralf; Couturier, Cyril

    2010-06-03

    Leptin mediates its metabolic effects through several leptin receptor (LEP-R) isoforms. In humans, long (LEPRb) and short (LEPRa,c,d) isoforms are generated by alternative splicing. Most of leptin's effects are believed to be mediated by the OB-Rb isoform. However, the role of short LEPR isoforms and the possible existence of heteromers between different isoforms are poorly understood. Using BRET1 and optimized co-immunoprecipitation, we observed LEPRa/b and LEPRb/c heteromers located at the plasma membrane and stabilized by leptin. Given the widespread coexpression of LEPRa and LEPRb, our results suggest that LEPRa/b heteromers may represent a major receptor species in most tissues. Copyright 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  9. Inhibition of platelet aggregation by AZD6140, a reversible oral P2Y12 receptor antagonist, compared with clopidogrel in patients with acute coronary syndromes

    DEFF Research Database (Denmark)

    Storey, Robert F; Husted, Steen; Harrington, Robert A

    2007-01-01

    OBJECTIVES: In a substudy of DISPERSE (Dose confIrmation Study assessing anti-Platelet Effects of AZD6140 vs. clopidogRel in non-ST-segment Elevation myocardial infarction)-2, we compared the antiplatelet effects of AZD6140 and clopidogrel and assessed the effects of AZD6140 in clopidogrel......-pretreated patients. BACKGROUND: Clopidogrel, in combination with aspirin, reduces cardiovascular events in patients with acute coronary syndromes (ACS). However, patients with poor inhibition of platelet aggregation with clopidogrel may be less well protected. AZD6140 is a reversible oral P2Y(12) receptor antagonist...... that has been studied in ACS patients in comparison with clopidogrel (DISPERSE-2 study). METHODS: Patients were randomized to receive either AZD6140 90 mg twice a day, AZD6140 180 mg twice a day, or clopidogrel 75 mg once a day for up to 12 weeks in a double-blind, double-dummy design. One...

  10. Galactose-specific recognition system of mammalian liver: receptor distribution on the hepatocyte cell surface

    OpenAIRE

    1981-01-01

    An isolated perfused liver system was used to study the distribution of asialoglycoprotein (ASGP) binding sites on rat hepatocyte cell surfaces. The number of surface receptors was quantitated by monitoring clearance of 125I-labeled ligands from the perfusate medium under two conditions that blocked their internalization: low temperature (less than 5 degrees C) or brief formaldehyde fixation. The cell surface distribution of binding sites was visualized in the electron microscope with either ...

  11. Cell surface-associated aggregation-promoting factor from Lactobacillus gasseri SBT2055 facilitates host colonization and competitive exclusion of Campylobacter jejuni.

    Science.gov (United States)

    Nishiyama, Keita; Nakazato, Akiko; Ueno, Shintaro; Seto, Yasuyuki; Kakuda, Tsutomu; Takai, Shinji; Yamamoto, Yuji; Mukai, Takao

    2015-11-01

    Campylobacter jejuni, one of the most common causes of gastroenteritis worldwide, is transmitted to humans through poultry. We previously reported that Lactobacillus gasseri SBT2055 (LG2055) reduced C. jejuni infection in human epithelial cells in vitro and inhibited pathogen colonization of chickens in vivo. This suggested that the LG2055 adhesion and/or co-aggregation phenotype mediated by cell-surface aggregation-promoting factors (APFs) may be important for the competitive exclusion of C. jejuni. Here, we show that cell surface-associated APF1 promoted LG2055 self-aggregation and adhesion to human epithelial cells and exhibited high affinity for the extracellular matrix component fibronectin. These effects were absent in the apf1 knockout mutant, indicating the role of APF1 in LG2055-mediated inhibition of C. jejuni in epithelial cells and chicken colonization. Similar to APF1, APF2 promoted the co-aggregation of LG2055 and C. jejuni but did not inhibit C. jejuni infection. Our data suggest a pivotal role for APF1 in mediating the interaction of LG2055 with human intestinal cells and in inhibiting C. jejuni colonization of the gastrointestinal tract. We thus provide new insight into the health-promoting effects of probiotics and mechanisms of competitive exclusion in poultry. Further research is needed to determine whether the probiotic strains reach the epithelial surface. © 2015 John Wiley & Sons Ltd.

  12. Intracellular dynamics of sst5 receptors in transfected COS-7 cells: maintenance of cell surface receptors during ligand-induced endocytosis.

    Science.gov (United States)

    Stroh, T; Jackson, A C; Sarret, P; Dal Farra, C; Vincent, J P; Kreienkamp, H J; Mazella, J; Beaudet, A

    2000-01-01

    Internalization of G protein-coupled receptors is crucial for resensitization of phosphorylation-desensitized receptors, but also for their long term desensitization through sequestration. To elucidate the mechanisms regulating cell surface availability of the somatostatin (SRIF) receptor subtype sst5, we characterized its internalization properties in transfected COS-7 cells using biochemical, confocal microscopic, and electron microscopic techniques. Our results demonstrated rapid and efficient sequestration of specifically bound [125I]Tyr0-D-Trp8-SRIF (up to 45% of bound radioactivity). Combined immunocytochemical detection of sst5 and visualization of a fluorescent SRIF analog by confocal microscopy revealed that whereas the internalized ligand progressively clustered toward the cell center with time, immunoreactive receptors remained predominantly associated with the plasma membrane. The preservation of cell surface receptors was confirmed by binding experiments on whole cells revealing a lack of saturability of [125I]Tyr0-D-Trp8-SRIF binding at 37 C. Binding was rendered saturable by the drug monensin, showing that receptor recycling played a key role in the preservation of cell surface receptors. Electron microscopy demonstrated that in addition to receptor recycling, internalization of receptor-ligand complexes triggered a massive recruitment of sst5 receptor molecules from intracellular stores to the membrane. This combination of recycling and recruitment of spare receptors may protect sst5 from long term down-regulation through sequestration and, therefore, facilitate extended SRIF signaling.

  13. Cell aggregation on agar as an indicator for cell-matrix adhesion: effects of opioids.

    Science.gov (United States)

    Debruyne, Delphine; Mareel, Marc; Vanhoecke, Barbara; Bracke, Marc

    2009-09-01

    The slow aggregation assay is generally used to study the functionality of cell-cell adhesion complexes. Single cells are seeded on a semisolid agar substrate in a 96-well plate and the cells spontaneously aggregate. We used HEK FLAG-MOP cells that stably overexpress the mu opioid receptor and the mu-opioid-receptor-selective agonists DAMGO and morphine to study whether other factors than functionality of cell-cell adhesions complexes can contribute to changes in the pattern of slow aggregation on agar. HEK FLAG-MOP cells formed small compact aggregates. In the presence of DAMGO and morphine, larger and fewer aggregates were formed in comparison to the vehicle control. These aggregates were localized in the center of the agar surface, whereas in the vehicle control they were dispersed over the substrate. However, in suspension culture on a Gyrotory shaker, no stimulation of aggregation was observed by DAMGO and morphine, showing that opioids do not affect affinity. A dissociation experiment revealed that HEK FLAG-MOP aggregates formed in the absence or presence of opioids are resistant to de-adhesion. We demonstrated that the larger aggregates are neither the result of cell growth stimulation by DAMGO and morphine. Since manipulations of the substrate such as increasing the agar concentration or mixing agar with agarose induced the same changes in the pattern of slow aggregation as treatment with opioids, we suggest that cell-substrate adhesion may be involved in opioid-stimulated aggregation.

  14. Influence of combined thrombin stimulation, surface activation, and receptor occupancy on organization of GPIb/IX receptors on human platelets.

    Science.gov (United States)

    White, J G; Krumwiede, M; Cocking-Johnson, D; Escolar, G

    1994-09-01

    Down-regulation and clearance of as many as 60-80% of GPIb/IX receptors from exposed surfaces on thrombin-activated platelets to channels of the open canalicular system (OCS) is considered to be a fundamental mechanism regulating platelet adhesivity in vitro and in vivo. The present study has combined thrombin stimulation in suspension, surface activation on formvar grids, receptor occupancy by von Willebrand factor (vWF) and exposure to anti-vWF antibody in an effort to demonstrate the removal of GPIb/IX receptors from activated cells. Individually the stimuli failed to cause any change in the frequency of GPIb/IX receptors. Combined, the stimuli were no more effective than when each was used alone. The only way to cause GPIb/IX to move was to add anti-vWF to thrombin-activated platelets allowed to spread on formvar grids and covered with multimers of ristocetin-activated human or bovine vWF. Translocation of GPIb/IX-vWF-anti-vWF complexes from peripheral margins into caps over cell centres, however, did not clear the peripheral zone of vWF binding capacity. Exposure of capped platelets after fixation to a second incubation with vWF demonstrated as many multimers extending from the central cap to the peripheral margins as were seen on platelets exposed a single time to vWF. Antibodies to GPIb, but not to GPIIb/IIIA, prevented the second labelling by vWF. Down-regulation or clearance of GPIb/IX, in light of this study, does not appear to be a fundamental mechanism modulating platelet adhesivity.

  15. Temporal upregulation of host surface receptors provides a window of opportunity for bacterial adhesion and disease.

    Science.gov (United States)

    Kc, Rajendra; Shukla, Shakti D; Walters, Eugene H; O'Toole, Ronan F

    2017-04-01

    Host surface receptors provide bacteria with a foothold from which to attach, colonize and, in some cases, invade tissue and elicit human disease. In this review, we discuss several key host receptors and cognate adhesins that function in bacterial pathogenesis. In particular, we examine the elevated expression of host surface receptors such as CEACAM-1, CEACAM-6, ICAM-1 and PAFR in response to specific stimuli. We explore how upregulated receptors, in turn, expose the host to a range of bacterial infections in the respiratory tract. It is apparent that exploitation of receptor induction for bacterial adherence is not unique to one body system, but is also observed in the central nervous, gastrointestinal and urogenital systems. Prokaryotic pathogens which utilize this mechanism for their infectivity include Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis and Escherichia coli. A number of approaches have been used, in both in vitro and in vivo experimental models, to inhibit bacterial attachment to temporally expressed host receptors. Some of these novel strategies may advance future targeted interventions for the prevention and treatment of bacterial disease.

  16. Imaging of Kiss-and-Run Exocytosis of Surface Receptors in Neuronal Cultures

    Directory of Open Access Journals (Sweden)

    Cristina eRoman-Vendrell

    2014-11-01

    Full Text Available Transmembrane proteins are continuously shuttled from the endosomal compartment to the neuronal plasma membrane by highly regulated and complex trafficking steps. These events are involved in many homeostatic and physiological processes such as neuronal growth, signaling, learning and memory among others. We have previously shown that endosomal exocytosis of the B2 adrenergic receptor (B2AR and the GluR1-containing AMPA receptor to the neuronal plasma membrane is mediated by two different types of vesicular fusion. Transient events in which receptors are delivered to the plasma membrane in a single kinetic step, and persistent events in which receptors remain clustered at the insertion site for a variable period of time before delivery to the cell surface. Here, by comparing the exocytosis of multiple receptors in dissociated hippocampal and striatal cultures, we show that persistent events are a general mechanism of vesicular delivery. Persistent events were only observed after 10 days in vitro, and their frequency increased with use of the calcium ionophore A23187 and with depolarization induced by KCl. Finally, we determined that vesicles producing persistent events remain at the plasma membrane, closing and reopening their fusion pore for a consecutive release of cargo in a mechanism reminiscent of synaptic kiss-and-run. These results indicate that the delivery of transmembrane receptors to the cell surface can be dynamically regulated by kiss-and-run exocytosis.

  17. Surface expression of NMDA receptor changes during memory consolidation in the crab Neohelice granulata

    Science.gov (United States)

    Hepp, Yanil; Salles, Angeles; Carbo-Tano, Martin

    2016-01-01

    The aim of the present study was to analyze the surface expression of the NMDA-like receptors during the consolidation of contextual learning in the crab Neohelice granulata. Memory storage is based on alterations in the strength of synaptic connections between neurons. The glutamatergic synapses undergo various forms of N-methyl-D aspartate receptor (NMDAR)-dependent changes in strength, a process that affects the abundance of other receptors at the synapse and underlies some forms of learning and memory. Here we propose a direct regulation of the NMDAR. Changes in NMDAR's functionality might be induced by the modification of the subunit's expression or cellular trafficking. This trafficking does not only include NMDAR's movement between synaptic and extra-synaptic localizations but also the cycling between intracellular compartments and the plasma membrane, a process called surface expression. Consolidation of contextual learning affects the surface expression of the receptor without affecting its general expression. The surface expression of the GluN1 subunit of the NMDAR is down-regulated immediately after training, up-regulated 3 h after training and returns to naïve and control levels 24 h after training. The changes in NMDAR surface expression observed in the central brain are not seen in the thoracic ganglion. A similar increment in surface expression of GluN1 in the central brain is observed 3 h after administration of the competitive GABAA receptor antagonist, bicuculline. These consolidation changes are part of a plasticity event that first, during the down-regulation, stabilizes the trace and later, at 3-h post-training, changes the threshold for synapse activation. PMID:27421895

  18. A sensitive electrochemiluminescence cytosensor for quantitative evaluation of epidermal growth factor receptor expressed on cell surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yanjuan; Zhang, Shaolian; Wen, Qingqing; Huang, Hongxing; Yang, Peihui, E-mail: typh@jnu.edu.cn

    2015-06-30

    Highlights: • EGF-cytosensor was used for evaluating EGFR expression level on cell surfaces. • CdSQDs and EGF were coated on magnetic beads (MBs) for ECL-probe. • Good sensitivity was achieved due to the signal amplification of ECL-probe. - Abstract: A sensitive electrochemiluminescence (ECL) strategy for evaluating the epidermal growth factor receptor (EGFR) expression level on cell surfaces was designed by integrating the specific recognition of EGFR expressed on MCF-7 cell surfaces with an epidermal growth factor (EGF)-funtionalized CdS quantum dots (CdSQDs)-capped magnetic bead (MB) probe. The high sensitivity of ECL probe of EGF-funtionalized CdSQD-capped-MB was used for competitive recognition with EGFR expressed on cell surfaces with recombinant EGFR protein. The changes of ECL intensity depended on both the cell number and the expression level of EGFR receptor on cell surfaces. A wide linear response to cells ranging from 80 to 4 × 10{sup 6} cells mL{sup −1} with a detection limit of 40 cells mL{sup −1} was obtained. The EGF-cytosensor was used to evaluate EGFR expression levels on MCF-7 cells, and the average number of EGFR receptor on single MCF-7 cells was 1.35 × 10{sup 5} with the relative standard deviation of 4.3%. This strategy was further used for in-situ and real-time evaluating EGFR receptor expressed on cell surfaces in response to drugs stimulation at different concentration and incubation time. The proposed method provided potential applications in the detection of receptors on cancer cells and anticancer drugs screening.

  19. Intrabody-mediated diverting of HP1β to the cytoplasm induces co-aggregation of H3-H4 histones and lamin-B receptor.

    Science.gov (United States)

    Cardinale, Alessio; Filesi, Ilaria; Singh, Prim B; Biocca, Silvia

    2015-10-15

    Diverting a protein from its intracellular location is a unique property of intrabodies. To interfere with the intracellular traffic of heterochromatin protein 1β (HP1β) in living cells, we have generated a cytoplasmic targeted anti-HP1β intrabody, specifically directed against the C-terminal portion of the molecule. HP1β is a conserved component of mouse and human constitutive heterochromatin involved in diverse nuclear functions including gene silencing, DNA repair and nuclear membrane assembly. We found that the anti-HP1β intrabody sequesters HP1β into cytoplasmic aggregates, inhibiting its traffic to the nucleus. Lamin B receptor (LBR) and a subset of core histones (H3/H4) are also specifically co-sequestered in the cytoplasm of anti-HP1β intrabody-expressing cells. Methylated histone H3 at K9 (Me9H3), a marker of constitutive heterochromatin, is not affected by the anti-HP1β intrabody expression. Hyper-acetylating conditions completely dislodge H3 from HP1β:LBR containing aggregates. The expression of anti-HP1β scFv fragments induces apoptosis, associated with an alteration of nuclear morphology. Both these phenotypes are specifically rescued either by overexpression of recombinant full length HP1β or by HP1β mutant containing the chromoshadow domain, but not by recombinant LBR protein. The HP1β-chromodomain mutant, on the other hand, does not rescue the phenotypes, but does compete with LBR for binding to HP1β. These findings provide new insights into the mode of action of cytoplasmic-targeted intrabodies and the interaction between HP1β and its binding partners involved in peripheral heterochromatin organisation. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Surface Expression of NMDA Receptor Changes during Memory Consolidation in the Crab "Neohelice granulata"

    Science.gov (United States)

    Hepp, Yanil; Salles, Angeles; Carbo-Tano, Martin; Pedreira, Maria Eugenia; Freudenthal, Ramiro

    2016-01-01

    The aim of the present study was to analyze the surface expression of the NMDA-like receptors during the consolidation of contextual learning in the crab "Neohelice granulata". Memory storage is based on alterations in the strength of synaptic connections between neurons. The glutamatergic synapses undergo various forms of…

  1. Scratching the surface: Regulation of cell surface receptors in cholesterol metabolism

    NARCIS (Netherlands)

    Nelson, J.K.

    2016-01-01

    Elevated plasma levels of low density lipoprotein cholesterol (LDL) are an established risk factor for the development of atherosclerosis and cardiovascular diseases. The LDL-Receptor is a key determinant in regulating LDL levels in plasma, and current lipid-lowering strategies aim to increase its

  2. Characterization of aggregates of surface modified fullerenes by asymmetrical flow field-flow fractionation with multi-angle light scattering detection.

    Science.gov (United States)

    Astefanei, Alina; Kok, Wim Th; Bäuerlein, Patrick; Núñez, Oscar; Galceran, Maria Teresa; de Voogt, Pim; Schoenmakers, Peter J

    2015-08-21

    Fullerenes are carbon nanoparticles with widespread biomedical, commercial and industrial applications. Attributes such as their tendency to aggregate and aggregate size and shape impact their ability to be transported into and through the environment and living tissues. Knowledge of these properties is therefore valuable for their human and environmental risk assessment as well as to control their synthesis and manufacture. In this work, asymmetrical flow-field flow fractionation (AF4) coupled to multi-angle light scattering (MALS) was used for the first time to study the size distribution of surface modified fullerenes with both polyhydroxyl and carboxyl functional groups in aqueous solutions having different pH (6.5-11) and ionic strength values (0-200mM) of environmental relevance. Fractionation key parameters such as flow rates, flow programming, and membrane material were optimized for the selected fullerenes. The aggregation of the compounds studied appeared to be indifferent to changes in solution pH, but was affected by changes in the ionic strength. Polyhydroxy-fullerenes were found to be present mostly as 4nm aggregates in water without added salt, but showed more aggregation at high ionic strength, with an up to 10-fold increase in their mean hydrodynamic radii (200mM), due to a decrease in the electrostatic repulsion between the nanoparticles. Carboxy-fullerenes showed a much stronger aggregation degree in water (50-100nm). Their average size and recoveries decreased with the increase in the salt concentration. This behavior can be due to enhanced adsorption of the large particles to the membrane at high ionic strength, because of their higher hydrophobicity and much larger particle sizes compared to polyhydroxy-fullerenes. The method performance was evaluated by calculating the run-to-run precision of the retention time (hydrodynamic radii), and the obtained RSD values were lower than 1%. MALS measurements showed aggregate sizes that were in good

  3. The role of Rabi splitting tuning in the dynamics of strongly coupled J-aggregates and surface plasmon polaritons in nanohole arrays.

    Science.gov (United States)

    Wang, Hai; Toma, Andrea; Wang, Hai-Yu; Bozzola, Angelo; Miele, Ermanno; Haddadpour, Ali; Veronis, Georgios; De Angelis, Francesco; Wang, Lei; Chen, Qi-Dai; Xu, Huai-Liang; Sun, Hong-Bo; Zaccaria, Remo Proietti

    2016-07-21

    We have investigated the influence of Rabi splitting tuning on the dynamics of strongly coupled J-aggregate/surface plasmon polariton systems. In particular, the Rabi splitting was tuned by modifying the J-aggregate molecule concentration while a polaritonic system was provided by a nanostructure formed by holes array in a golden layer. From the periodic and concentration changes we have identified, through numerical and experimental steady-state analyses, the best geometrical configuration for maximizing Rabi splitting, which was then used for transient absorption measurements. It was found that in transient absorption spectra, under upper band excitation, two bleaching peaks appear when a nanostructured polaritonic pattern is used. Importantly, their reciprocal distance increases upon increase of J-aggregate concentration, a result confirmed by steady-state analysis. In a similar manner it was also found that the lifetime of the upper band is intimately related to the coupling strength. In particular, we argue that with strong coupling strength, i.e. high J-aggregate concentration, a short lifetime of the upper band has to be expected due to the suppression of the bottleneck effect. This result supports the idea that the dynamics of hybrid systems is profoundly dependent on Rabi splitting.

  4. Chemical-potential-dependent gap opening at the Dirac surface states of Bi2Se3 induced by aggregated substitutional Cr atoms.

    Science.gov (United States)

    Chang, Cui-Zu; Tang, Peizhe; Wang, Yi-Lin; Feng, Xiao; Li, Kang; Zhang, Zuocheng; Wang, Yayu; Wang, Li-Li; Chen, Xi; Liu, Chaoxing; Duan, Wenhui; He, Ke; Ma, Xu-Cun; Xue, Qi-Kun

    2014-02-07

    With angle-resolved photoemission spectroscopy, gap opening is resolved at up to room temperature in the Dirac surface states of molecular beam epitaxy grown Cr-doped Bi2Se3 topological insulator films, which, however, show no long-range ferromagnetic order down to 1.5 K. The gap size is found decreasing with increasing electron-doping level. Scanning tunneling microscopy and first-principles calculations demonstrate that substitutional Cr atoms aggregate into superparamagnetic multimers in the Bi2Se3 matrix, which contribute to the observed chemical-potential-dependent gap opening in the Dirac surface states without long-range ferromagnetic order.

  5. Inhibitory effects of two G protein-coupled receptor kinases on the cell surface expression and signaling of the human adrenomedullin receptor

    Energy Technology Data Exchange (ETDEWEB)

    Kuwasako, Kenji, E-mail: kuwasako@med.miyazaki-u.ac.jp [Frontier Science Research Center, University of Miyazaki, Miyazaki, 889-1692 (Japan); Sekiguchi, Toshio [Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Ishikawa, 927-0553 (Japan); Nagata, Sayaka [Division of Circulatory and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692 (Japan); Jiang, Danfeng; Hayashi, Hidetaka [Frontier Science Research Center, University of Miyazaki, Miyazaki, 889-1692 (Japan); Murakami, Manabu [Department of Pharmacology, Hirosaki University, Graduate School of Medicine, Hirosaki, 036-8562 (Japan); Hattori, Yuichi [Department of Molecular and Medical Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194 (Japan); Kitamura, Kazuo [Division of Circulatory and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692 (Japan); Kato, Johji [Frontier Science Research Center, University of Miyazaki, Miyazaki, 889-1692 (Japan)

    2016-02-19

    Receptor activity-modifying protein 2 (RAMP2) enables the calcitonin receptor-like receptor (CLR, a family B GPCR) to form the type 1 adrenomedullin receptor (AM{sub 1} receptor). Here, we investigated the effects of the five non-visual GPCR kinases (GRKs 2 through 6) on the cell surface expression of the human (h)AM{sub 1} receptor by cotransfecting each of these GRKs into HEK-293 cells that stably expressed hRAMP2. Flow cytometric analysis revealed that when coexpressed with GRK4 or GRK5, the cell surface expression of the AM{sub 1} receptor was markedly decreased prior to stimulation with AM, thereby attenuating both the specific [{sup 125}I]AM binding and AM-induced cAMP production. These inhibitory effects of both GRKs were abolished by the replacement of the cytoplasmic C-terminal tail (C-tail) of CLR with that of the calcitonin receptor (a family B GPCR) or β{sub 2}-adrenergic receptor (a family A GPCR). Among the sequentially truncated CLR C-tail mutants, those lacking the five residues 449–453 (Ser-Phe-Ser-Asn-Ser) abolished the inhibition of the cell surface expression of CLR via the overexpression of GRK4 or GRK5. Thus, we provided new insight into the function of GRKs in agonist-unstimulated GPCR trafficking using a recombinant AM{sub 1} receptor and further determined the region of the CLR C-tail responsible for this GRK function. - Highlights: • We discovered a novel function of GRKs in GPCR trafficking using human CLR/RAMP2. • GRKs 4 and 5 markedly inhibited the cell surface expression of human CLR/RAMP2. • Both GRKs exhibited highly significant receptor signaling inhibition. • Five residues of the C-terminal tail of CLR govern this function of GRKs.

  6. Enterovirus 71 uses cell surface heparan sulfate glycosaminoglycan as an attachment receptor.

    Science.gov (United States)

    Tan, Chee Wah; Poh, Chit Laa; Sam, I-Ching; Chan, Yoke Fun

    2013-01-01

    Enterovirus 71 (EV-71) infections are usually associated with mild hand, foot, and mouth disease in young children but have been reported to cause severe neurological complications with high mortality rates. To date, four EV-71 receptors have been identified, but inhibition of these receptors by antagonists did not completely abolish EV-71 infection, implying that there is an as yet undiscovered receptor(s). Since EV-71 has a wide range of tissue tropisms, we hypothesize that EV-71 infections may be facilitated by using receptors that are widely expressed in all cell types, such as heparan sulfate. In this study, heparin, polysulfated dextran sulfate, and suramin were found to significantly prevent EV-71 infection. Heparin inhibited infection by all the EV-71 strains tested, including those with a single-passage history. Neutralization of the cell surface anionic charge by polycationic poly-d-lysine and blockage of heparan sulfate by an anti-heparan sulfate peptide also inhibited EV-71 infection. Interference with heparan sulfate biosynthesis either by sodium chlorate treatment or through transient knockdown of N-deacetylase/N-sulfotransferase-1 and exostosin-1 expression reduced EV-71 infection in RD cells. Enzymatic removal of cell surface heparan sulfate by heparinase I/II/III inhibited EV-71 infection. Furthermore, the level of EV-71 attachment to CHO cell lines that are variably deficient in cell surface glycosaminoglycans was significantly lower than that to wild-type CHO cells. Direct binding of EV-71 particles to heparin-Sepharose columns under physiological salt conditions was demonstrated. We conclude that EV-71 infection requires initial binding to heparan sulfate as an attachment receptor.

  7. Morphological Specifications of the Bird Schistosome Cercariae and Surface Carbohydrates as Receptors for Lectins

    Directory of Open Access Journals (Sweden)

    I Moebedi

    2007-04-01

    Full Text Available Background: To determine the morphological specifications of the bird schistosomes cercaria from Lymnaea gedrosiana and to detect the surface carbohydrates as receptors for host lectins in the host-parasite relationship systems such as avian schistosomiasis and human cercarial dermatitis. Methods: One hundred ninety two snails collected from Dezful areas in Khuzestan Province, in the south west of Iran, during 2005-2006 were examined for cercariae using shedding and crushing methods. In addition, surface carbohydrates on the cercariae were detected by lentil (Lens culinaris lectins. Results: From the total number of Lymnaea gedrosiana, which examined for bird schistosomes cercaria, 9(4% snails were found to be infected with furcocercus cercaria of the bird schistosomes (probably Gigantobilharzia sp.. Mannose monosaccharide CH2OH (CHOH4CHO as surface carbohydrate was also detected on the cercariae. Conclusion: Mannose carbohydrate on these cercariae may be used as receptor by lectins.

  8. An entirely cell-based system to generate single-chain antibodies against cell surface receptors.

    Science.gov (United States)

    Lipes, Barbara D; Chen, Yu-Hsun; Ma, Hongzheng; Staats, Herman F; Kenan, Daniel J; Gunn, Michael Dee

    2008-05-30

    The generation of recombinant antibodies (Abs) using phage display is a proven method to obtain a large variety of Abs that bind with high affinity to a given antigen. Traditionally, the generation of single-chain Abs depends on the use of recombinant proteins in several stages of the procedure. This can be a problem, especially in the case of cell-surface receptors, because Abs generated and selected against recombinant proteins may not bind the same protein expressed on a cell surface in its native form and because the expression of some receptors as recombinant proteins is problematic. To overcome these difficulties, we developed a strategy to generate single-chain Abs that does not require the use of recombinant protein at any stage of the procedure. In this strategy, stably transfected cells are used for the immunization of mice, measuring Ab responses to immunization, panning the phage library, high-throughput screening of arrayed phage clones, and characterization of recombinant single-chain variable regions. This strategy was used to generate a panel of single-chain Abs specific for the innate immunity receptor Toll-like receptor 2. Once generated, individual single-chain variable regions were subcloned into an expression vector allowing the production of recombinant Abs in insect cells, thus avoiding the contamination of recombinant Abs with microbial products. This cell-based system efficiently generates Abs that bind to native molecules on the cell surface, bypasses the requirement of recombinant protein production, and avoids risks of microbial component contamination.

  9. Involvement of the calcium-sensing receptor in mineral trioxide aggregate-induced osteogenic gene expression in murine MC3T3-E1 cells.

    Science.gov (United States)

    Yasukawa, Takuya; Hayashi, Makoto; Tanabe, Natsuko; Tsuda, Hiromasa; Suzuki, Yusuke; Kawato, Takayuki; Suzuki, Naoto; Maeno, Masao; Ogiso, Bunnai

    2017-07-26

    Mineral trioxide aggregate (MTA) has excellent biocompatibility as well as bioactivity, including an ability to induce osteoblast differentiation. We examined the effects of the calcium-sensing receptor (CaSR) on osteogenic gene expression induced by MTA. MC3T3-E1 cells were cultured with or without (control) MTA. The expression levels of Runx2, type I collagen, and CaSR genes were analyzed by real-time polymerase chain reaction and their products were measured using enzyme-linked immunosorbent assays. The levels were increased significantly in cells exposed to MTA compared with control. Next, MC3T3-E1 cells were cultured with MTA and EGTA (a calcium chelator), because calcium ions were released continuously from MTA into the culture. Expression levels were decreased to control levels by MTA plus EGTA. NPS2143 (a CaSR antagonist) also reduced MTA-induced gene expression. These results suggest that MTA induced osteogenic gene expressions of Runx2 and type I collagen via CaSR in MC3T3-E1 cells.

  10. A model for the biosynthesis and transport of plasma membrane-associated signaling receptors to the cell surface

    Directory of Open Access Journals (Sweden)

    Sorina Claudia Popescu

    2012-04-01

    Full Text Available Intracellular protein transport is emerging as critical in determining the outcome of receptor-activated signal transduction pathways. In plants, relatively little is known about the nature of the molecular components and mechanisms involved in coordinating receptor synthesis and transport to the cell surface. Recent advances in this field indicate that signaling pathways and intracellular transport machinery converge and coordinate to render receptors competent for signaling at their plasma membrane activity sites. The biogenesis and transport to the cell surface of signaling receptors appears to require both general trafficking and receptor-specific factors. Several molecular determinants, residing or associated with compartments of the secretory pathway and known to influence aspects in receptor biogenesis, are discussed and integrated into a predictive cooperative model for the functional expression of signaling receptors at the plasma membrane.

  11. The signaling phospholipid PIP3 creates a new interaction surface on the nuclear receptor SF-1.

    Science.gov (United States)

    Blind, Raymond D; Sablin, Elena P; Kuchenbecker, Kristopher M; Chiu, Hsiu-Ju; Deacon, Ashley M; Das, Debanu; Fletterick, Robert J; Ingraham, Holly A

    2014-10-21

    The signaling phosphatidylinositol lipids PI(4,5)P2 (PIP2) and PI(3,4,5)P3 (PIP3) bind nuclear receptor 5A family (NR5As), but their regulatory mechanisms remain unknown. Here, the crystal structures of human NR5A1 (steroidogenic factor-1, SF-1) ligand binding domain (LBD) bound to PIP2 and PIP3 show the lipid hydrophobic tails sequestered in the hormone pocket, as predicted. However, unlike classic nuclear receptor hormones, the phosphoinositide head groups are fully solvent-exposed and complete the LBD fold by organizing the receptor architecture at the hormone pocket entrance. The highest affinity phosphoinositide ligand PIP3 stabilizes the coactivator binding groove and increases coactivator peptide recruitment. This receptor-ligand topology defines a previously unidentified regulatory protein-lipid surface on SF-1 with the phosphoinositide head group at its nexus and poised to interact with other proteins. This surface on SF-1 coincides with the predicted binding site of the corepressor DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region on chromosome X), and importantly harbors missense mutations associated with human endocrine disorders. Our data provide the structural basis for this poorly understood cluster of human SF-1 mutations and demonstrates how signaling phosphoinositides function as regulatory ligands for NR5As.

  12. An escort for GPCRs: implications for regulation of receptor density at the cell surface.

    Science.gov (United States)

    Achour, Lamia; Labbé-Jullié, Catherine; Scott, Mark G H; Marullo, Stefano

    2008-10-01

    G-protein-coupled receptors (GPCRs) are dynamically regulated by various mechanisms that tune their response to external stimuli. Modulation of their plasma membrane density, via trafficking between subcellular compartments, constitutes an important process in this context. Substantial information has been accumulated on cellular pathways that remove GPCRs from the cell surface for subsequent degradation or recycling. In comparison, much less is known about the mechanisms controlling trafficking of neo-synthesized GPCRs from intracellular compartments to the cell surface. Although GPCR export to the plasma membrane is commonly considered to mostly implicate the default, unregulated secretory pathway, an increasing number of observations indicate that trafficking to the plasma membrane from the endoplasmic reticulum might be tightly regulated and involve specific protein partners. Moreover, a new paradigm is emerging in some cellular contexts, in which stocks of functional receptors retained within intracellular compartments can be rapidly mobilized to the plasma membrane to maintain sustained physiological responsiveness.

  13. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.

    2014-01-01

    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

  14. Surface expression of only gamma delta and/or alpha beta T cell receptor heterodimers by cells with four (alpha, beta, gamma, delta) functional receptor chains

    NARCIS (Netherlands)

    Saito, T.; Hochstenbach, F.; Marusic-Galesic, S.; Kruisbeek, A. M.; BRENNER, M.; GERMAIN, R. N.

    1988-01-01

    Surface expression of TCR dimers by cells synthesizing three or four distinct types of receptor chains was analyzed. Cells containing intact gamma, alpha, and beta chains had only gamma delta dimers on the cell surface. In human PEER cells, addition of a functional alpha chain led to the loss of

  15. Ligand-specific regulation of the extracellular surface of a G-protein-coupled receptor

    Energy Technology Data Exchange (ETDEWEB)

    Bokoch, Michael P.; Zou, Yaozhong; Rasmussen, Søren G.F.; Liu, Corey W.; Nygaard, Rie; Rosenbaum, Daniel M.; Fung, Juan José; Choi, Hee-Jung; Thian, Foon Sun; Kobilka, Tong Sun; Puglisi, Joseph D.; Weis, William I.; Pardo, Leonardo; Prosser, R. Scott; Mueller, Luciano; Kobilka, Brian K. (Stanford-MED); (Toronto); (BMS); (UAB, Spain)

    2010-01-14

    G-protein-coupled receptors (GPCRs) are seven-transmembrane proteins that mediate most cellular responses to hormones and neurotransmitters. They are the largest group of therapeutic targets for a broad spectrum of diseases. Recent crystal structures of GPCRs have revealed structural conservation extending from the orthosteric ligand-binding site in the transmembrane core to the cytoplasmic G-protein-coupling domains. In contrast, the extracellular surface (ECS) of GPCRs is remarkably diverse and is therefore an ideal target for the discovery of subtype-selective drugs. However, little is known about the functional role of the ECS in receptor activation, or about conformational coupling of this surface to the native ligand-binding pocket. Here we use NMR spectroscopy to investigate ligand-specific conformational changes around a central structural feature in the ECS of the {beta}{sub 2} adrenergic receptor: a salt bridge linking extracellular loops 2 and 3. Small-molecule drugs that bind within the transmembrane core and exhibit different efficacies towards G-protein activation (agonist, neutral antagonist and inverse agonist) also stabilize distinct conformations of the ECS. We thereby demonstrate conformational coupling between the ECS and the orthosteric binding site, showing that drugs targeting this diverse surface could function as allosteric modulators with high subtype selectivity. Moreover, these studies provide a new insight into the dynamic behaviour of GPCRs not addressable by static, inactive-state crystal structures.

  16. Malaria inhibits surface expression of complement receptor-1 in monocyte/macrophages causing decreased immunecomplex internalization

    Science.gov (United States)

    Fernandez-Arias, Cristina; Lopez, Jean Pierre; Hernandez-Perez, Jean Nikolae; Bautista-Ojeda, Maria Dolores; Branch, OraLee; Rodriguez, Ana

    2013-01-01

    Complement receptor 1 (CR1) expressed on the surface of phagocytic cells binds complement-bound IC playing an important role in the clearance of circulating immunecomplexes (IC). This receptor is critical to prevent accumulation of IC, which can contribute to inflammatory pathology. Accumulation of circulating IC is frequently observed during malaria, although the factors contributing to this accumulation are not clearly understood. We have observed that the surface expression of CR1 on monocyte/macrophages and B cells is strongly reduced in mice infected with Plasmodium yoelii, a rodent malaria model. Monocyte/macrophages from these infected mice present a specific inhibition of complement-mediated internalization of IC caused by the decreased CR1 expression. Accordingly, mice show accumulation of circulating IC and deposition of IC in the kidneys that inversely correlates with the decrease in CR1 surface expression. Our results indicate that malaria induces a significant decrease on surface CR1 expression in the monocyte/macrophage population that results in deficient internalization of IC by monocyte/macrophages. To determine whether this phenomenon is found in human malaria patients, we have analyzed 92 patients infected with either P. falciparum (22) or P. vivax (70), the most prevalent human malaria parasites. The levels of surface CR1 on peripheral monocyte/macrophages and B cells of these patients show a significant decrease compared to uninfected control individuals in the same area. We propose that this decrease in CR1 plays an essential role in impaired IC clearance during malaria. PMID:23440418

  17. Localization of neonatal Fc receptor for IgG in aggregated lymphoid nodules area in abomasum of Bactrian camels (Camelus bactrianus of different ages

    Directory of Open Access Journals (Sweden)

    Wang-Dong Zhang

    2016-10-01

    Full Text Available Abstract Background The neonatal Fc receptor (FcRn plays a crucial role in transporting IgG and associated antigens across polarized epithelial barriers in mucosal immunity. However, it was not clear that FcRn expression in aggregated lymphoid nodules area (ALNA in abomasum, a unique and important mucosal immune structure discovered only in Bactrian camels. In the present study, 27 Alashan Bactrian camels were divided into the following five age groups: fetus (10–13 months of gestation, young (1–2 years, pubertal (3–5 years, middle-aged (6–16 years and old (17–20 years. The FcRn expressions were observed and analyzed in detail with histology, immunohistochemistry, micro-image analysis and statistical methods. Results The results showed that the FcRn was expressed in mucosal epithelial cells of ALNA from the fetus to the old group, although the expression level rapidly declined in old group; moreover, after the ALNA maturated, the FcRn expression level in the non-follicle-associated epithelium (non-FAE was significantly higher than that in FAE (P < 0.05. In addition, the FcRn was also expressed in the vessel endothelium, smooth muscle tissue, and macrophages and dendritic cells (DCs of secondary lymphoid follicles (sLFs. Conclusions It was demonstrated that FcRn was mainly expressed in non-FAE, the effector sites, although which was expressed in FAE, the inductive sites for mucosal immunity. And it was also expressed in DCs and macrophages in sLFs of all ages of Bactrian camels. The results provided a powerful evidence that IgG (including HCAb could participate in mucosal immune response and tolerance in ALNA of Bactrian camels through FcRn transmembrane transport.

  18. Selective role of sterol regulatory element binding protein isoforms in aggregated LDL-induced vascular low density lipoprotein receptor-related protein-1 expression.

    Science.gov (United States)

    Costales, P; Aledo, R; Vérnia, S; Das, A; Shah, V H; Casado, M; Badimon, L; Llorente-Cortés, V

    2010-12-01

    Low density lipoprotein receptor-related protein (LRP1) is upregulated in vascular smooth muscle cells by intravascular aggregated LDL (agLDL) - LDL trapped in the arterial intima and systemic LDL. LRP1 upregulation in hypercholesterolemic aortas is concomitant with SREBP downregulation. However, the specific role of SREBP isoforms in LRP1 transcription and LDL-induced LRP1 upregulation in human vascular smooth muscle cells (VSMC) is unknown. In the present study we report that specific silencing of either SREBP-1 or SREBP-2 enhanced LRP1 whereas overexpression of the active SREBP isoforms decreased LRP1 expression. Gel mobility shift and ChIP assays demonstrated that SREBP-1a, SREBP-1c and SREBP-2 were able to bind to three putative SRE sequences; SRE-A (-1042 to -1028), SRE-B (-115 to -101) and SRE-C (+226 to +234). ChIP assays demonstrated that agLDL (100μg/mL, 24h) significantly and specifically decreased SREBP-2 binding to the LRP1 promoter. Luciferase assays demonstrated that agLDL increased the transcriptional activity of A/B or A/C double mutants but failed to increase that of the double B/C mutant. Our results show that both SREBP-1 and SREBP-2 negatively modulated LRP1 transcription. Furthermore, agLDL exerted an upregulatory effect on LRP1 expression by decreasing SREBP-2 binding to LRP1 promoter. Two SRE-like sequences control the response of LRP1 to agLDL. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  19. Quantification of epidermal growth factor receptor expression level and binding kinetics on cell surfaces by surface plasmon resonance imaging.

    Science.gov (United States)

    Zhang, Fenni; Wang, Shaopeng; Yin, Linliang; Yang, Yunze; Guan, Yan; Wang, Wei; Xu, Han; Tao, Nongjian

    2015-10-06

    Epidermal growth factor receptor (EGFR, also known as ErbB-1 or HER-1) is a membrane bound protein that has been associated with a variety of solid tumors and the control of cell survival, proliferation, and metabolism. Quantification of the EGFR expression level in cell membranes and the interaction kinetics with drugs are thus important for cancer diagnosis and treatment. Here we report mapping of the distribution and interaction kinetics of EGFR in their native environment with the surface plasmon resonance imaging (SPRi) technique. The monoclonal anti-EGFR antibody was used as a model drug in this study. The binding of the antibody to EGFR overexpressed A431 cells was monitored in real time, which was found to follow the first-order kinetics with an association rate constant (ka) and dissociation rate constant (kd) of (2.7 ± 0.6) × 10(5) M(-1) s(-1) and (1.4 ± 0.5) × 10(-4) s(-1), respectively. The dissociation constant (KD) was determined to be 0.53 ± 0.26 nM with up to seven-fold variation among different individual A431 cells. In addition, the averaged A431 cell surface EGFR density was found to be 636/μm(2) with an estimation of 5 × 10(5) EGFR per cell. Additional measurement also revealed that different EGFR positive cell lines (A431, HeLa, and A549) show receptor density dependent anti-EGFR binding kinetics. The results demonstrate that SPRi is a valuable tool for direct quantification of membrane protein expression level and ligand binding kinetics at single cell resolution. Our findings show that the local environment affects the drug-receptor interactions, and in situ measurement of membrane protein binding kinetics is important.

  20. 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.

  1. Therapeutic opportunities for targeting the ubiquitous cell surface receptor CD47

    Science.gov (United States)

    Soto-Pantoja, David R.; Stein, Erica V.; Rogers, Natasha M.; Sharifi-Sanjani, Maryam; Isenberg, Jeffrey S.; Roberts, David D.

    2013-01-01

    Introduction CD47 is a ubiquitously expressed cell surface receptor that serves as a counter-receptor for SIRPα in recognition of self by the innate immune system. Independently, CD47 also functions as an important signaling receptor for regulating cell responses to stress. Areas covered We review the expression, molecular interactions, and pathophysiological functions of CD47 in the cardiovascular and immune systems. CD47 was first identified as a potential tumor marker, and we examine recent evidence that its dysregulation contributes to cancer progression and evasion of anti-tumor immunity. We further discuss therapeutic strategies for enhancing or inhibiting CD47 signaling and applications of such agents in preclinical models of ischemia and ischemia/reperfusion injuries, organ transplantation, pulmonary hypertension, radioprotection, and cancer. Expert opinion Ongoing studies are revealing a central role of CD47 for conveying signals from the extracellular microenvironment that limit cell and tissue survival upon exposure to various types of stress. Based on this key function, therapeutics targeting CD47 or its ligands thrombospondin-1 and SIRPα could have broad applications spanning reconstructive surgery, engineering of tissues and biocompatible surfaces, vascular diseases, diabetes, organ transplantation, radiation injuries, inflammatory diseases, and cancer. PMID:23101472

  2. Effect of surface topography on actin dynamics and receptor clustering in B cells

    Science.gov (United States)

    Ketchum, Christina; Sun, Xiaoyu; Song, Wenxia; Fourkas, John; Upadhyaya, Arpita

    2013-03-01

    B cells are activated upon binding of the B cell receptor (BCR) with antigen on the surface of antigen presenting cells (APC). Activated B cells deform and spread on the surface of APCs which may comprise of complex membrane topologies. In order to model the diverse range of topographies that B cells may encounter, substrates fabricated with vertical ridges separated by gaps ranging from hundreds of nm to microns were coated with activating antigen to enable B cell spreading. Simultaneous imaging of actin and BCR shows that the organization of both depends profoundly on the ridge spacing. On smaller ridge spacing (Cells on larger ridge spacing (>2 microns) exhibit central actin patches and peripheral actin waves and form semi-stable polymerization zones at ridges, while BCR distribution is more homogeneous. Our results indicate that surface topography may be a critical determinant of cytoskeletal dynamics and the spatiotemporal organization of signaling clusters. Biophysics Program

  3. Lysyl oxidase drives tumour progression by trapping EGF receptors at the cell surface.

    Science.gov (United States)

    Tang, HaoRan; Leung, Leo; Saturno, Grazia; Viros, Amaya; Smith, Duncan; Di Leva, Gianpiero; Morrison, Eamonn; Niculescu-Duvaz, Dan; Lopes, Filipa; Johnson, Louise; Dhomen, Nathalie; Springer, Caroline; Marais, Richard

    2017-04-18

    Lysyl oxidase (LOX) remodels the tumour microenvironment by cross-linking the extracellular matrix. LOX overexpression is associated with poor cancer outcomes. Here, we find that LOX regulates the epidermal growth factor receptor (EGFR) to drive tumour progression. We show that LOX regulates EGFR by suppressing TGFβ1 signalling through the secreted protease HTRA1. This increases the expression of Matrilin2 (MATN2), an EGF-like domain-containing protein that traps EGFR at the cell surface to facilitate its activation by EGF. We describe a pharmacological inhibitor of LOX, CCT365623, which disrupts EGFR cell surface retention and delays the growth of primary and metastatic tumour cells in vivo. Thus, we show that LOX regulates EGFR cell surface retention to drive tumour progression, and we validate the therapeutic potential of inhibiting this pathway with the small molecule inhibitor CCT365623.

  4. Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates on Mars

    Science.gov (United States)

    Schuerger, A. C.; Kern, R. G.

    2003-01-01

    In order to minimize the forward contamination of Mars, spacecraft are assembled under clean-room conditions that often require several procedures to clean and sterilize components. Surface characteristics of spacecraft materials may contribute to microbial survival by protecting spores from sterilizing agents, including UV irradiation on the surface of Mars. The primary objective of this study was to evaluate the effects of surface characteristics of several spacecraft materials on the survival of Bacillus subtilis spores under simulated Martian conditions.

  5. 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

    , K. (2005). Nano-to-micro scale dynamics of P-selectin detachment from leukocyte interfaces: I. Separation of PSGL-1 from the cell cytoskeleton. Biophys. J. 88, 2288-2298]. Retracting cells from receptor-surface attachments at many different speeds revealed that the kinetic rate for receptor......-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...... constellation of associated proteins, perhaps switching some aspect of their function. Thus, if used in conjunction with cleverly engineered cell lines targeting receptor-cytoskeletal linkages, probing the kinetics of receptor-cytoskeletal unbinding with ultrasensitve force techniques can provide unique...

  6. The role of natural processes and surface energy of inhaled engineered nanoparticles on aggregation and corona formation.

    Science.gov (United States)

    Tsuda, Akira; Venkata, Nagarjun Konduru

    2016-04-01

    The surface chemistry of engineered nanoparticles (ENPs) becomes more important as their size decreases and enters the nanometer-range. This review explains the fundamental properties of the surface chemistry of nanoparticles, and argues that their agglomeration and the formation of corona around them are natural processes that reduce surface energy. ENP agglomeration and surface corona formation are further discussed in the context of inhaled ENPs, as the lung is a major port of ENP entry to the body. The pulmonary surfactant layer, which the inhaled ENPs first encounter as they land on the lung surface, represents a unique environment with a variety of well-defined biomolecules. Many factors, such as hydrophobicity, surface charge of ENPs, protein/phospholipid concentrations of the alveolar lining fluid, etc. influence the complex processes of ENP agglomeration and corona formation in the alveolar lining fluid, and these events occur even before the ENPs reach the cells. We suggest that molecular dynamic simulations can represent a promising future direction for research of the behavior of inhaled ENPs, complementing the experimental approaches. Moreover, we want to remind biologists working on ENPs of the importance relationship between ENP surface energy and size.

  7. Immunogenicity of self-associated aggregates and chemically cross-linked conjugates of the 42 kDa Plasmodium falciparum merozoite surface protein-1.

    Directory of Open Access Journals (Sweden)

    Feng Qian

    Full Text Available Self-associated protein aggregates or cross-linked protein conjugates are, in general, more immunogenic than oligomeric or monomeric forms. In particular, the immunogenicity in mice of a recombinant malaria transmission blocking vaccine candidate, the ookinete specific Plasmodium falciparum 25 kDa protein (Pfs25, was increased more than 1000-fold when evaluated as a chemical cross-linked protein-protein conjugate as compared to a formulated monomer. Whether alternative approaches using protein complexes improve the immunogenicity of other recombinant malaria vaccine candidates is worth assessing. In this work, the immunogenicity of the recombinant 42 kDa processed form of the P. falciparum merozoite surface protein 1 (MSP1(42 was evaluated as a self-associated, non-covalent aggregate and as a chemical cross-linked protein-protein conjugate to ExoProtein A, which is a recombinant detoxified form of Pseudomonas aeruginosa exotoxin A. MSP1(42 conjugates were prepared and characterized biochemically and biophysically to determine their molar mass in solution and stoichiometry, when relevant. The immunogenicity of the MSP1(42 self-associated aggregates, cross-linked chemical conjugates and monomers were compared in BALB/c mice after adsorption to aluminum hydroxide adjuvant, and in one instance in association with the TLR9 agonist CPG7909 with an aluminum hydroxide formulation. Antibody titers were assessed by ELISA. Unlike observations made for Pfs25, no significant enhancement in MSP1(42 specific antibody titers was observed for any conjugate as compared to the formulated monomer or dimer, except for the addition of the TLR9 agonist CPG7909. Clearly, enhancing the immunogenicity of a recombinant protein vaccine candidate by the formation of protein complexes must be established on an empirical basis.

  8. Laboratory Evaluation of Aggregate Polishing as a function of Load and Velocity : Application to the Prediction of Damages on Skid Resistance of Pavement Surface due to Trucks and Passenger Cars

    OpenAIRE

    KANE, Malal; ZHAO, Dan; DE LARRARD, François; DO, Minh Tan

    2012-01-01

    Skid resistance of road surfaces depends mostly on pavement texture. This texture is usually divided to two components:microtexture and macrotexture. Microtexture refers to the smallscale texture of the road aggregate component while macrotexture refers to the large-scale texture of the road as a whole due to the aggregate particle arrangement. Both components contribute to the generation of friction between tyre and road. However, due to traffic, the firstcited component is continuously poli...

  9. A Hydrophobic Gold Surface Triggers Misfolding and Aggregation of the Amyloidogenic Josephin Domain in Monomeric Form, While Leaving the Oligomers Unaffected

    Science.gov (United States)

    Apicella, Alessandra; Soncini, Monica; Deriu, Marco Agostino; Natalello, Antonino; Bonanomi, Marcella; Dellasega, David; Tortora, Paolo; Regonesi, Maria Elena; Casari, Carlo Spartaco

    2013-01-01

    Protein misfolding and aggregation in intracellular and extracellular spaces is regarded as a main marker of the presence of degenerative disorders such as amyloidoses. To elucidate the mechanisms of protein misfolding, the interaction of proteins with inorganic surfaces is of particular relevance, since surfaces displaying different wettability properties may represent model systems of the cell membrane. Here, we unveil the role of surface hydrophobicity/hydrophilicity in the misfolding of the Josephin domain (JD), a globular-shaped domain of ataxin-3, the protein responsible for the spinocerebellar ataxia type 3. By means of a combined experimental and theoretical approach based on atomic force microscopy, Fourier transform infrared spectroscopy and molecular dynamics simulations, we reveal changes in JD morphology and secondary structure elicited by the interaction with the hydrophobic gold substrate, but not by the hydrophilic mica. Our results demonstrate that the interaction with the gold surface triggers misfolding of the JD when it is in native-like configuration, while no structural modification is observed after the protein has undergone oligomerization. This raises the possibility that biological membranes would be unable to affect amyloid oligomeric structures and toxicity. PMID:23527026

  10. A hydrophobic gold surface triggers misfolding and aggregation of the amyloidogenic Josephin domain in monomeric form, while leaving the oligomers unaffected.

    Directory of Open Access Journals (Sweden)

    Alessandra Apicella

    Full Text Available Protein misfolding and aggregation in intracellular and extracellular spaces is regarded as a main marker of the presence of degenerative disorders such as amyloidoses. To elucidate the mechanisms of protein misfolding, the interaction of proteins with inorganic surfaces is of particular relevance, since surfaces displaying different wettability properties may represent model systems of the cell membrane. Here, we unveil the role of surface hydrophobicity/hydrophilicity in the misfolding of the Josephin domain (JD, a globular-shaped domain of ataxin-3, the protein responsible for the spinocerebellar ataxia type 3. By means of a combined experimental and theoretical approach based on atomic force microscopy, Fourier transform infrared spectroscopy and molecular dynamics simulations, we reveal changes in JD morphology and secondary structure elicited by the interaction with the hydrophobic gold substrate, but not by the hydrophilic mica. Our results demonstrate that the interaction with the gold surface triggers misfolding of the JD when it is in native-like configuration, while no structural modification is observed after the protein has undergone oligomerization. This raises the possibility that biological membranes would be unable to affect amyloid oligomeric structures and toxicity.

  11. Identification and characterization of the murine cell surface receptor for the urokinase-type plasminogen activator

    DEFF Research Database (Denmark)

    Solberg, H.; Løber, D.; Eriksen, J

    1992-01-01

    Cell-binding experiments have indicated that murine cells on their surface have specific binding sites for mouse urokinase-type plasminogen activator (u-PA). In contrast to the human system, chemical cross-linking studies with an iodinated ligand did not yield any covalent adducts in the murine...... of this variant yielded a polypeptide with an apparent M(r) of about 30,000, which corresponds to the Mr calculated from the cDNA derived protein sequence of mouse u-PAR. Receptor-bound mouse u-PA could be released by phosphatidylinositol-specific phospholipase C treatment, indicating that mouse u-PAR is attached...... to the cell surface by glycosylphosphatidylinositol. Purification of the two mouse u-PAR variant proteins by diisopropylfluorophosphate-inactivated mouse u-PA-Sepharose affinity chromatography yielded two silver-stained bands when analysed by SDS/PAGE, corresponding in electrophoretic mobility to those seen...

  12. Modeling study of surface ozone source-receptor relationships in East Asia

    Science.gov (United States)

    Li, J.

    2016-12-01

    Ozone source-receptor relationships over East Asia have been quantitatively investigated using a chemical transport model including an on-line tracer-tagged procedure, with a particular focus on the source regions of different daily ozone mixing ratios.Comparison with observations showed that the model reproduced surface ozone and tropospheric nitrogen dioxide column densities.Long-range transport from outside East Asia contributed the greatest fraction to annual surface ozone over remote regions, the Korean peninsula, and Japan, reaching 50%-80% of total ozone.Self-contributions accounted for 5%-20% ozonein the Korean peninsula and Japan, whereas the contribution of trans-boundary transport from photochemical production in China was less than 5%-10%. At extra-high ozone levels, self-contributions reached 50%-60% in the Korean peninsula.Ozone source-receptor relationships showed high seasonal variability over East Asia.Significant transport was also found between sub-regions in China, which presents a great challenge to policy-makers because most current control strategies are confined to specific regions.

  13. The Cell Surface Estrogen Receptor, G Protein- Coupled Receptor 30 (GPR30, is Markedly Down Regulated During Breast Tumorigenesis

    Directory of Open Access Journals (Sweden)

    Indira Poola

    2008-01-01

    Full Text Available Background: GPR30 is a cell surface estrogen receptor that has been shown to mediate a number of non-genomic rapid effects of estrogen and appear to balance the signaling of estrogen and growth factors. In addition, progestins appear to use GPR30 for their actions. Therefore, GPR30 could play a critical role in hormonal regulation of breast epithelial cell integrity. Deregulation of the events mediated by GPR30 could contribute to tumorigenesis.Methods: To understand the role of GPR30 in the deregulation of estrogen signaling processes during breast carcinogenesis, we have undertaken this study to investigate its expression at mRNA levels in tumor tissues and their matched normal tissues. We compared its expression at mRNA levels by RT quantitative real-time PCR relative to GAPDH in ERα”—positive (n = 54 and ERα”—negative (n = 45 breast cancer tissues to their matched normal tissues.Results: We report here, for the first time, that GPR30 mRNA levels were significantly down-regulated in cancer tissues in comparison with their matched normal tissues (p 0.0001 by two sided paired t-test. The GPR30 expression levels were significantly lower in tumor tissues from patients (n = 29 who had lymph node metastasis in comparison with tumors from patients (n = 53 who were negative for lymph node metastasis (two sample t-test, p 0.02, but no association was found with ERα, PR and other tumor characteristics.Conclusions: Down-regulation of GPR30 could contribute to breast tumorigenesis and lymph node metastasis.

  14. Influence of localized surface plasmon resonance and free electrons on the optical properties of ultrathin Au films: a study of the aggregation effect.

    Science.gov (United States)

    Li, X D; Chen, T P; Liu, Y; Leong, K C

    2014-03-10

    The contributions of localized surface plasmon resonance (LSPR) and Drude (free electrons) absorption to the complex dielectric function of ultrathin Au films were investigated with spectroscopic ellipsometry. When the Au film thickness is thinner than ~10 nm, Au nanoparticles (NPs) are formed as a result of the discontinuity in the films, leading to the emergence of LSPR of Au NPs; and the LSPR exhibits a splitting when the films thinner than ~8 nm, which could be attributed to the near-field coupling of the Au NPs and/or the inhomogeneous polarizations of the Au NPs. On the other hand, the delocalization of electrons in Au NPs due to the aggregation of Au NPs in a thicker film leads to an increase in the free-electron absorption and a suppression of the LSPR.

  15. Effect of UV radiation on the surface of mammalian immunocompetent cells. 1. The change in expression of some antigens and receptors of murine spleen lymphocyte surface

    Energy Technology Data Exchange (ETDEWEB)

    Krylenkov, V.A.; Malygin, A.M. (AN SSSR, Leningrad. Inst. Tsitologii)

    1982-12-01

    Short-wave (254nm) and long-wave (365 nm) UV rays (ShUS and LUV rays) induce the increase in the expression of surface markers of T lymphocytes-THETA(Thy-1) antigens and B lymphocytes-MBLA-antigens and EAS receptors when affecting mouse spleen cells in nonlethal and small lethal doses. Total cell content with T and B lymphocyte characters in an irradiated suspension exceeds even the total cell quantity in non-irradiated suspension (100%) which points to the possibility of the expression of plasmatic membrane antigens and receptors not manifested on the surface of nonirradiated lymphocytes. In the isolethal dose range (LD/sup 15/-LD/sup 28/) ShUV rays suppress and LUV rays induce further increase of THETA and MBLA antigens expression. Among B lymphocytes surface markers the MBLA antigens are more resistant to ShUV an LUV radiation as compared with the EAC receptors.

  16. Surface rheological properties of liquid-liquid interfaces stabilized by protein fibrillar aggregates and protein-polysaccharide complexes

    NARCIS (Netherlands)

    Humblet-Hua, K.N.P.; Linden, van der E.; Sagis, L.M.C.

    2013-01-01

    In this study we have investigated the surface rheological properties of oil-water interfaces stabilized by fibrils from lysozyme (long and semi-flexible and short and rigid ones), fibrils from ovalbumin (short and semi-flexible), lysozyme-pectin complexes, or ovalbumin-pectin complexes. We have

  17. Effect of bleaching agents having a neutral pH on the surface of mineral trioxide aggregate using electron microscopy and energy dispersive X-ray microanalysis

    Science.gov (United States)

    Kazia, Nooh; Suvarna, Nithin; Shetty, Harish Kumar; Kumar, Pradeep

    2016-01-01

    Aim: To investigate the effect of bleaching agents having a neutral pH on the surface of mineral trioxide aggregate (MTA) used as a coronal seal material for nonvital bleaching, beneath the bleaching agent, with the help of energy dispersive X-ray microanalysis and scanning electron microscopy (SEM). Materials and Methods: Six samples of plastic tubes filled with white MTA (Angelus white) were kept in 100% humidity for 21 days. Each sample was divided into 2 and made into 12 samples. These were then divided into three groups. Group A was exposed to Opalescence Boost 40% hydrogen peroxide (HP) (Ultradent). Group B to Opalescence 10% carbamide peroxide (Ultradent) and Group C (control group) not exposed to any bleaching agent. After recommended period of exposure to bleaching agents according to manufacturers’ instructions, the samples were observed under SEM with an energy dispersive X-ray microanalysis system (JSM-6380 LA). Results: There were no relevant changes in color and no statistically significant surface structure changes of the MTA in both the experimental groups. Conclusion: The present findings suggest that even high concentration HP containing bleaching agents with neutral pH can be used on the surface of MTA without causing structural changes. The superior sealing ability of MTA and the high alkalinity would prevent cervical resorption postbleaching. PMID:27656061

  18. Adhesion, activation, and aggregation of blood platelets and biofilm formation on the surfaces of titanium alloys Ti6Al4V and Ti6Al7Nb.

    Science.gov (United States)

    Walkowiak-Przybyło, M; Klimek, L; Okrój, W; Jakubowski, W; Chwiłka, M; Czajka, A; Walkowiak, B

    2012-03-01

    Titanium alloys are still on the top list of fundamental materials intended for dental, orthopedics, neurological, and cardiovascular implantations. Recently, a special attention has been paid to vanadium-free titanium alloy, Ti6Al7Nb, that seems to represent higher biocompatibility than traditional Ti6Al4V alloy. Surprisingly, these data are not thoroughly elaborated in the literature; particularly there is a lack of comparative experiments conducted simultaneously and at the same conditions. Our study fills these shortcomings in the field of blood contact and microbiological colonization. To observe platelets adhesion and biofilm formation on the surfaces of compared titanium alloys, fluorescence microscope Olympus GX71 and scanning electron microscope HITACHI S-3000N were used. Additionally, flow cytometry analysis of platelets aggregation and activation in the whole blood after contact with sample surface, as an essential tool for biomaterial thrombocompatibility assessment, was proposed. As a result of our study it was demonstrated that polished surfaces of Ti6Al7Nb and Ti6Al4V alloys after contact with whole citrated blood and E. coli bacterial cells exhibit a considerable difference. Overall, it was established that Ti6Al4V has distinct tendency to higher thrombogenicity, more excessive bacterial biofilm formation and notable cytotoxic properties in comparison to Ti6Al7Nb. However, we suggest these studies should be extended for other types of cells and biological objects. Copyright © 2012 Wiley Periodicals, Inc.

  19. Cell surface estrogen receptor alpha is upregulated during subchronic metabolic stress and inhibits neuronal cell degeneration.

    Directory of Open Access Journals (Sweden)

    Cristiana Barbati

    Full Text Available In addition to the classical nuclear estrogen receptor, the expression of non-nuclear estrogen receptors localized to the cell surface membrane (mER has recently been demonstrated. Estrogen and its receptors have been implicated in the development or progression of numerous neurodegenerative disorders. Furthermore, the pathogenesis of these diseases has been associated with disturbances of two key cellular programs: apoptosis and autophagy. An excess of apoptosis or a defect in autophagy has been implicated in neurodegeneration. The aim of this study was to clarify the role of ER in determining neuronal cell fate and the possible implication of these receptors in regulating either apoptosis or autophagy. The human neuronal cell line SH-SY5Y and mouse neuronal cells in primary culture were thus exposed to chronic minimal peroxide treatment (CMP, a form of subcytotoxic minimal chronic stress previously that mimics multiple aspects of long-term cell stress and represents a limited molecular proxy for neurodegenerative processes. We actually found that either E2 or E2-bovine serum albumin construct (E2BSA, i.e. a non-permeant form of E2 was capable of modulating intracellular cell signals and regulating cell survival and death. In particular, under CMP, the up-regulation of mERα, but not mERβ, was associated with functional signals (ERK phosphorylation and p38 dephosphorylation compatible with autophagic cytoprotection triggering and leading to cell survival. The mERα trafficking appeared to be independent of the microfilament system cytoskeletal network but was seemingly associated with microtubular apparatus network, i.e., to MAP2 molecular chaperone. Importantly, antioxidant treatments, administration of siRNA to ERα, or the presence of antagonist of ERα hindered these events. These results support that the surface expression of mERα plays a pivotal role in determining cell fate, and that ligand-induced activation of mER signalling exerts a

  20. Estradiol coupling to human monocyte nitric oxide release is dependent on intracellular calcium transients: evidence for an estrogen surface receptor.

    Science.gov (United States)

    Stefano, G B; Prevot, V; Beauvillain, J C; Fimiani, C; Welters, I; Cadet, P; Breton, C; Pestel, J; Salzet, M; Bilfinger, T V

    1999-10-01

    We tested the hypothesis that estrogen acutely stimulates constitutive NO synthase (cNOS) activity in human peripheral monocytes by acting on an estrogen surface receptor. NO release was measured in real time with an amperometric probe. 17beta-estradiol exposure to monocytes stimulated NO release within seconds in a concentration-dependent manner, whereas 17alpha-estradiol had no effect. 17beta-estradiol conjugated to BSA (E2-BSA) also stimulated NO release, suggesting mediation by a membrane surface receptor. Tamoxifen, an estrogen receptor inhibitor, antagonized the action of both 17beta-estradiol and E2-BSA, whereas ICI 182,780, a selective inhibitor of the nuclear estrogen receptor, had no effect. We further showed, using a dual emission microfluorometry in a calcium-free medium, that the 17beta-estradiol-stimulated release of monocyte NO was dependent on the initial stimulation of intracellular calcium transients in a tamoxifen-sensitive process. Leeching out the intracellular calcium stores abolished the effect of 17beta-estradiol on NO release. RT-PCR analysis of RNA obtained from the cells revealed a strong estrogen receptor-alpha amplification signal and a weak beta signal. Taken together, a physiological dose of estrogen acutely stimulates NO release from human monocytes via the activation of an estrogen surface receptor that is coupled to increases in intracellular calcium.

  1. Expression of surface and intracellular Toll-like receptors by mature mast cells.

    Science.gov (United States)

    Agier, Justyna; Żelechowska, Paulina; Kozłowska, Elżbieta; Brzezińska-Błaszczyk, Ewa

    2016-01-01

    Nowadays, more and more data indicate that mast cells play an important role in host defense against pathogens. That is why it is essential to understand the expression of Toll-like receptors (TLRs) by mast cells, because these molecules play particularly significant role in initiation host defense against microorganisms as they recognize both wide range of microbial pathogen-associated molecular patterns (PAMPs) and various endogenous damage-associated molecular patterns (DAMPs) released in response to infection. Therefore, we examined the constitutive expression of both surface and endosomal TLRs in rat native fully mature tissue mast cells. By the use of qRT-PCR we found that these cells express mRNAs for TLR2, TLR3, TLR4, TLR5, TLR7, and TLR9. The expression of TLR3, TLR4, TLR5, TLR7, and TLR9 transcripts were low and comparable and only the expression of TLR2 transcript was significant. By the use of flow cytometry technique, we clearly documented that mast cells express TLR2, TLR4, and TLR5 on cell surface, while TLR3, TLR7, and TLR9 proteins are located both on the cell membrane and intracellularly. The highest expression was observed for TLR5 and the lowest for surface TLR7. These observations undoubtedly indicate that mature tissue mast cells have a broad set of TLR molecules, thus can recognize and bind bacterial, viral, and fungal PAMPs as well as various endogenous molecules generated in response to infection.

  2. Expression of surface and intracellular Toll-like receptors by mature mast cells

    Directory of Open Access Journals (Sweden)

    Justyna Agier

    2017-01-01

    Full Text Available Nowadays, more and more data indicate that mast cells play an important role in host defense against pathogens. That is why it is essential to understand the expression of Toll-like receptors (TLRs by mast cells, because these molecules play particularly significant role in initiation host defense against microorganisms as they recognize both wide range of microbial pathogen-associated molecular patterns (PAMPs and various endogenous damage-associated molecular patterns (DAMPs released in response to infection. Therefore, we examined the constitutive expression of both surface and endosomal TLRs in rat native fully mature tissue mast cells. By the use of qRT-PCR we found that these cells express mRNAs for TLR2, TLR3, TLR4, TLR5, TLR7, and TLR9. The expression of TLR3, TLR4, TLR5, TLR7, and TLR9 transcripts were low and comparable and only the expression of TLR2 transcript was significant. By the use of flow cytometry technique, we clearly documented that mast cells express TLR2, TLR4, and TLR5 on cell surface, while TLR3, TLR7, and TLR9 proteins are located both on the cell membrane and intracellularly. The highest expression was observed for TLR5 and the lowest for surface TLR7. These observations undoubtedly indicate that mature tissue mast cells have a broad set of TLR molecules, thus can recognize and bind bacterial, viral, and fungal PAMPs as well as various endogenous molecules generated in response to infection.

  3. Identification and characterization of the murine cell surface receptor for the urokinase-type plasminogen activator

    DEFF Research Database (Denmark)

    Solberg, H; Løber, D; Eriksen, J

    1992-01-01

    system, but in ligand-blotting analysis, two mouse u-PA-binding proteins could be visualized. To confirm that these proteins are the murine counterpart of the human u-PA receptor (u-PAR), a peptide was derived from the murine cDNA clone assigned to represent the murine u-PAR due to cross......Cell-binding experiments have indicated that murine cells on their surface have specific binding sites for mouse urokinase-type plasminogen activator (u-PA). In contrast to the human system, chemical cross-linking studies with an iodinated ligand did not yield any covalent adducts in the murine......-hybridization and pronounced sequence similarity with human u-PAR cDNA [Kristensen, P., Eriksen, J., Blasi, F. & Danø, K. (1991) J. Cell Biol. 115, 1763-1771]. A rabbit antiserum raised against this peptide specifically recognized two polypeptide bands with electrophoretic mobilities identical to those identified by ligand...

  4. Screening Effect of PEG on Avidin Binding to Liposome Surface Receptors

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Mouritsen, Ole G.; Jørgensen, Kent

    2000-01-01

    This study investigates the screening effect of poly(ethylene glycol)-phospholipids (PE-PEG) on the interaction of avidin with PEGylated liposomes containing surface-bound biotin ligands. The influence of grafting density and lipopolymer chain length is examined. A simple fluorescence assay...... involving a receptor-mediated fluorescence increase of BODIPY-labeled avidin upon binding to biotinylated lipids is employed to study the screening effect of submicellar concentrations of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine-N-[poly(ethylene glycol)-2000] (PE-PEG(2000)) and 1.2-dipalmitoyl......-sn-glycero-3-phosphatidylethanolamine N-[poly(ethylene glycol)-5000] (PE-PEG(5000)) incorporated into 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) liposomes. The results show that incorporation of lipopolymers into DPPC lipid bilayers reduces binding of avidin to the biotinylated liposomes...

  5. Conserved cysteine residues in the extracellular loop of the human P2X(1) receptor form disulfide bonds and are involved in receptor trafficking to the cell surface.

    Science.gov (United States)

    Ennion, Steven J; Evans, Richard J

    2002-02-01

    P2X receptors contain 10 conserved cysteines in the extracellular loop. To investigate whether these residues form disulfide bonds, we created a series of single and double cysteine-alanine mutants in the human P2X(1) receptor. Mutants were expressed in Xenopus laevis oocytes and effects on ATP potency, cell-surface expression, and N-biotinoylaminoethyl methanethiosulfonate (MTSEA-Biotin) labeling of free cysteines were determined. For the majority of single mutants, only a modest decrease (2- to 5-fold) in ATP potency was recorded. For mutants C261A and C270A, the peak current amplitudes were reduced by 93.6 +/- 2.0 and 95.0 +/- 1.0%, respectively; this was a result of low cell-surface expression of these mutant receptors. Wild-type receptors showed no labeling with MTSEA-biotin suggesting that all 10 cysteine residues in the extracellular loop are disulfide-bonded. Mutation of cysteines at positions 126, 132, 149, 159, 217, and 227 resulted in MTSEA-biotinylation of a free cysteine residue created by the disruption of a disulfide bond and provides direct biochemical evidence for at least three disulfide bonds. Based on phenotypic comparisons of single and double cysteine mutants, we propose the following disulfide bond pairs in the human P2X(1) receptor: C117-C165, C126-C149, C132-C159, C217-C227, and C261-C270. None of these bonds are individually essential for channel function. However, trafficking of the receptor to the cell membrane is severely reduced by disruption of the C261-C270 disulfide bond or disruption of C117-C165 together with another bond.

  6. Biomimetically grown apatite spheres from aggregated bioglass nanoparticles with ultrahigh porosity and surface area imply potential drug delivery and cell engineering applications.

    Science.gov (United States)

    El-Fiqi, Ahmed; Buitrago, Jennifer O; Yang, Sung Hee; Kim, Hae-Won

    2017-09-15

    Here we communicate the generation of biomimetically grown apatite spheres from aggregated bioglass nanoparticles and the potential properties applicable for drug delivery and cell/tissue engineering. Ion releasing nanoparticulates of bioglass (85%SiO 2 -15%CaO) in a mineralizing medium show an intriguing dynamic phenomenon - aggregation, mineralization to apatite, integration and growth into micron-sized (1.5-3μm) spheres. During the progressive ionic dissolution/precipitation reactions, nano-to-micro-morphology, glass-to-crystal composition, and the physico-chemical properties (porosity, surface area, and charge) change dynamically. With increasing reaction period, the apatite becomes more crystallized with increased crystallinity and crystal size, and gets a composition closer to the stoichiometry. The developed microspheres exhibit hierarchical surface nanostructure, negative charge (ς-potential of -20mV), and ultrahigh mesoporosity (mesopore size of 6.1nm, and the resultant surface area of 63.7m 2 /g and pore volume of 0.153cm 3 /g) at 14days of mineralization, which are even higher than those of its precursor bioglass nanoparticles. Thanks to these properties, the biomimetic mineral microspheres take up biological molecules effectively, i.e., loading capacity of positive-charged protein is over 10%. Of note, the release is highly sustainable at a constant rate, i.e., profiling almost 'zero-order' kinetics for 4weeks, suggesting the potential usefulness as protein delivery systems. The biomimetic mineral microspheres hold some remnant Si in the core region, and release calcium, phosphate, and silicate ions over the test period, implying the long-term ionic-related therapeutic functions. The mesenchymal stem cells favour the biomimetic spheres with an excellent viability. Due to the merit of sizes (a few micrometers), the spheres can be intercalated into cells, mediating cellular interactions in 3D cell-spheroid engineering, and also can stimulate osteogenic

  7. Up-cycling waste glass to minimal water adsorption/absorption lightweight aggregate by rapid low temperature sintering: optimization by dual process-mixture response surface methodology.

    Science.gov (United States)

    Velis, Costas A; Franco-Salinas, Claudia; O'Sullivan, Catherine; Najorka, Jens; Boccaccini, Aldo R; Cheeseman, Christopher R

    2014-07-01

    Mixed color waste glass extracted from municipal solid waste is either not recycled, in which case it is an environmental and financial liability, or it is used in relatively low value applications such as normal weight aggregate. Here, we report on converting it into a novel glass-ceramic lightweight aggregate (LWA), potentially suitable for high added value applications in structural concrete (upcycling). The artificial LWA particles were formed by rapidly sintering (glass powder with clay mixes using sodium silicate as binder and borate salt as flux. Composition and processing were optimized using response surface methodology (RSM) modeling, and specifically (i) a combined process-mixture dual RSM, and (ii) multiobjective optimization functions. The optimization considered raw materials and energy costs. Mineralogical and physical transformations occur during sintering and a cellular vesicular glass-ceramic composite microstructure is formed, with strong correlations existing between bloating/shrinkage during sintering, density and water adsorption/absorption. The diametrical expansion could be effectively modeled via the RSM and controlled to meet a wide range of specifications; here we optimized for LWA structural concrete. The optimally designed LWA is sintered in comparatively low temperatures (825-835 °C), thus potentially saving costs and lowering emissions; it had exceptionally low water adsorption/absorption (6.1-7.2% w/wd; optimization target: 1.5-7.5% w/wd); while remaining substantially lightweight (density: 1.24-1.28 g.cm(-3); target: 0.9-1.3 g.cm(-3)). This is a considerable advancement for designing effective environmentally friendly lightweight concrete constructions, and boosting resource efficiency of waste glass flows.

  8. An in vitro study to assess the setting and surface crazing of conventional glass ionomer cement when layered over partially set mineral trioxide aggregate.

    Science.gov (United States)

    Ballal, Suma; Venkateshbabu, Nagendrababu; Nandini, Suresh; Kandaswamy, Deivanayagam

    2008-04-01

    The aim of our study was to assess the setting time and surface crazing of glass ionomer cement when layered over partially set mineral trioxide aggregate (MTA). To assess setting time, 40 hollow, cylindrical stainless steel molds were taken and equally divided into 4 groups. In groups I, II, and III glass ionomer cement was layered over partially setting MTA at 45 minutes, 4 hours, and 3 days, respectively. Group IV was used as a control. An additional 50 specimens were prepared for assessment of surface crazing. Twenty specimens (groups I and II) were prepared to study normal and desiccated patterns of conventional glass ionomer cement, respectively. Thirty specimens (groups III, IV, and V) were prepared by layering glass ionomer cement over partially set MTA at various time intervals. All the specimens were stained with red ink and analyzed for craze lines by light microscopy. From our study, it was observed that there was no statistical difference in setting time of glass ionomer cement when layered over partially set MTA in comparison to that of the control group. No craze lines were observed in those specimens (groups III, IV, and V) when viewed under staining and light microscopy. It could be concluded that conventional glass ionomer cement might be layered over partially set MTA after 45 minutes and could be used for single visit procedures.

  9. Surface aggregation of urinary proteins and aspartic acid-rich peptides on the faces of calcium oxalate monohydrate investigated by in situ force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, M L; Qiu, S R; Hoyer, J R; Casey, W H; Nancollas, G H; De Yoreo, J J

    2008-05-28

    The growth of calcium oxalate monohydrate in the presence of Tamm-Horsfall protein (THP), osteopontin (OPN), and the 27-residue synthetic peptides (DDDS){sub 6}DDD and (DDDG){sub 6}DDD [where D = aspartic acid and X = S (serine) or G (glycine)] was investigated via in situ atomic force microscopy (AFM). The results show that these three growth modulators create extensive deposits on the crystal faces. Depending on the modulator and crystal face, these deposits can occur as discrete aggregates, filamentary structures, or uniform coatings. These proteinaceous films can lead to either the inhibition or increase of the step speeds (with respect to the impurity-free system) depending on a range of factors that include peptide or protein concentration, supersaturation and ionic strength. While THP and the linear peptides act, respectively, to exclusively increase and inhibit growth on the (-101) face, both exhibit dual functionality on the (010) face, inhibiting growth at low supersaturation or high modulator concentration and accelerating growth at high supersaturation or low modulator concentration. Based on analyses of growth morphologies and dependencies of step speeds on supersaturation and protein or peptide concentration, we argue for a picture of growth modulation that accounts for the observations in terms of the strength of binding to the surfaces and steps and the interplay of electrostatic and solvent-induced forces at crystal surface.

  10. CARbodies: Human Antibodies Against Cell Surface Tumor Antigens Selected From Repertoires Displayed on T Cell Chimeric Antigen Receptors

    OpenAIRE

    Alonso-Camino, Vanesa; Sánchez-Martín, David; Compte, Marta; Nuñez-Prado, Natalia; Diaz, Rosa M; Vile, Richard; Alvarez-Vallina, Luis

    2013-01-01

    A human single-chain variable fragment (scFv) antibody library was expressed on the surface of human T cells after transduction with lentiviral vectors (LVs). The repertoire was fused to a first-generation T cell receptor ζ (TCRζ)-based chimeric antigen receptor (CAR). We used this library to isolate antibodies termed CARbodies that recognize antigens expressed on the tumor cell surface in a proof-of-principle system. After three rounds of activation-selection there was a clear repertoire res...

  11. Fluorescence Techniques for Measuring Kinetics of Specific Binding of Hormone to Cell Surface Receptors.

    Science.gov (United States)

    Hellen, Edward Herbert

    This thesis presents theoretical calculations and technical advances relevant to total internal reflection/ fluorescence photobleaching recovery (tir/fpr), and results from experiments using tir/fpr to measure the dissociation rate constant of epidermal growth factor (egf) hormone interacting with its receptor molecule on A431 cells. The classical electromagnetic calculations describe fluorescence emission from fluorophores near an interface (possibly metal coated). It is well known that an interface alters the emission properties of nearby fluorophores. Most previous classical calculations model the fluorophore as a fixed-amplitude dipole oscillator. However, for fluorophores under steady illumination, a fixed-power dipole is more appropriate. This modification corresponds to normalizing the fixed-amplitude dipole's intensity by its total dissipated power. The results for the fixed-power model differ nontrivially from the fixed-amplitude model. The observation-angle -dependent intensity as a function of the fluorophore's orientation and distance from the surface is calculated. General expressions are derived for the emission power as observed through a circular-aperture collection system located on either side of the interface. A system for maintaining long-term focus of samples under high-magnification quantitative observation in an epi-illumination optical microscope is described. Focus -dependent changes in the backreflection of an off-axis HeNe laser generate negative feedback signals which drive a dc motor coupled to the fine-focus knob of the microscope. This system has several advantages: (1) it is compatible and nonobstructive with concurrent data acqusition of sample intensities; (2) it requires no alteration of the sample, stage, or objective; (3) it monitors the position of sample areas very near to those under observation; (4) it is inexpensive. The system can hold a glass coverslip sample to within 0.5 μm of its preset focus position. Prismless tir

  12. Surface clustering of metabotropic glutamate receptor 1 induced by long Homer proteins

    Directory of Open Access Journals (Sweden)

    Kammermeier Paul J

    2006-01-01

    Full Text Available Abstract Background Metabotropic glutamate receptors (mGluRs regulate neuronal excitability and synaptic strength. The group I mGluRs, mGluR1 and 5, are widespread in the brain and localize to post-synaptic sites. The Homer protein family regulates group I mGluR function and distribution. Constitutively expressed 'long' Homer proteins (Homer 1b, 1c, 2 and 3 induce dendritic localization of group I mGluRs and receptor clustering, either internally or on the plasma membrane. Short Homer proteins (Homer 1a, Ania-3 exhibit regulated expression and act as dominant negatives, producing effects on mGluR distribution and function that oppose those of the long Homer proteins. There remains some controversy over whether long Homer proteins induce receptor internalization by inducing retention in the endoplasmic reticulum, or induce mGluR clustering on the plasma membrane. Further, an exhaustive study of the effects of each long Homer isoform on mGluR distribution has not been published. Results The distribution of a GFP-tagged group I mGluR, mGluR1-GFP, was examined in the absence of Homer proteins and in the presence of several Homer isoforms expressed in sympathetic neurons from the rat superior cervical ganglion (SCG using total internal reflection fluorescence (TIRF-M and confocal microscopy. Quantitative analysis of mGluR1-GFP fluorescence using TIRF-M revealed that expression of each long Homer isoform tested (Homer 1b, 1c, 2b and 3 induced a significant degree of surface clustering. Using confocal imaging, Homer-induced mGluR clusters were observed intra-cellularly as well as on the plasma membrane. Further, in approximately 40% of neurons co-expressing mGluR1-GFP and Homer 1b, intracellular inclusions were observed, but plasma membrane clusters were also documented in some Homer 1b coexpressing cells. Conclusion All long Homer proteins examined (Homer 1b, 1c, 2b and 3 induced a significant degree of mGluR1-GFP clustering on the plasma membrane

  13. Receptor-Mediated Surface Charge Inversion Platform Based on Porous Silicon Nanoparticles for Efficient Cancer Cell Recognition and Combination Therapy.

    Science.gov (United States)

    Zhang, Feng; Correia, Alexandra; Mäkilä, Ermei; Li, Wei; Salonen, Jarno; Hirvonen, Jouni J; Zhang, Hongbo; Santos, Hélder A

    2017-03-22

    Negatively charged surface-modified drug delivery systems are promising for in vivo applications as they have more tendency to accumulate in tumor tissues. However, the inefficient cell uptake of these systems restricts their final therapeutic performance. Here, we have fabricated a receptor-mediated surface charge inversion nanoparticle made of undecylenic acid modified, thermally hydrocarbonized porous silicon (UnTHCPSi) nanoparticles core and sequentially modified with polyethylenimine (PEI), methotrexate (MTX), and DNA aptamer AS1411 (herein termed as UnTHCPSi-PEI-MTX@AS1411) for enhancing the cell uptake of nucleolin-positive cells. The efficient interaction of AS1411 and the relevant receptor nucleolin caused the disintegration of the negative-charged AS1411 surface. The subsequent surface charge inversion and exposure of the active targeting ligand, MTX, enhanced the cell uptake of the nanoparticles. On the basis of this synergistic effect, the UnTHCPSi-PEI-MTX@AS1411 (hydrodynamic diameter is 242 nm) were efficiently internalized by nucleolin-positive MDA-MB-231 breast cancer cells, with an efficiency around 5.8 times higher than that of nucleolin-negative cells (NIH 3T3 fibroblasts). The receptor competition assay demonstrated that the major mechanism (more than one-half) of the internalized nanoparticles in MDA-MB-231 cells was due to the receptor-mediated surface charge inversion process. Finally, after loading of sorafenib, the nanosystem showed efficient performance for combination therapy with an inhibition ratio of 35.6%.

  14. Multi-surface composite vs stainless steel crown restorations after mineral trioxide aggregate pulpotomy: a randomized controlled trial.

    Science.gov (United States)

    Hutcheson, Candice; Seale, N Sue; McWhorter, Alton; Kerins, Carolyn; Wright, John

    2012-01-01

    Parents increasingly request esthetic restorations for their children's teeth. This split mouth, randomized controlled trial compared primary molars treated with white MTA pulpotomies and restored with either multi-surface composites (MSC) or stainless steel crowns (SSC). Forty matched, contra-lateral pairs of molars received MTA pulpotomies and were randomly assigned to MSC or SSC restorations and evaluated clinically and radiographically at 6 and 12 months. Two calibrated, blinded examiners evaluated and scored radiographs. Thirty-seven matched pairs were evaluated at 6 months, and 31 were available at 12 months. All teeth in both groups were radiographically and clinically successful at 6 and 12 months. Dentin bridge formation was noted in 20% of the primary molars by 12 months. Although not significant, the composite group exhibited fewer intact clinical margins than the SSC group. The vast majority (94%) of teeth restored with composite displayed gray discoloration at follow-up exams, which did not appear to affect the quality of the restoration and is believed to be associated with the white MTA. The white MTA pulpotomies succeeded over 12 months regardless of the restoration; however, the teeth restored with composite were not as durable nor considered an esthetic alternative to the SSC.

  15. Locally available aggregate and sediment production

    Science.gov (United States)

    Randy B. Foltz; Mark Truebe

    2003-01-01

    Selection of suitable locally available materials to build strong and durable roads with aggregate surfaces is desired to minimize road construction and maintenance costs and to minimize the detrimental effects of sedimentation. Eighteen aggregates were selected from local sources in Idaho, Oregon, South Dakota, and Washington State. Aggregate was placed in shallow...

  16. Delineating PAS-HAMP interaction surfaces and signalling-associated changes in the aerotaxis receptor Aer.

    Science.gov (United States)

    Garcia, Darysbel; Watts, Kylie J; Johnson, Mark S; Taylor, Barry L

    2016-04-01

    The Escherichia coli aerotaxis receptor, Aer, monitors cellular oxygen and redox potential via FAD bound to a cytosolic PAS domain. Here, we show that Aer-PAS controls aerotaxis through direct, lateral interactions with a HAMP domain. This contrasts with most chemoreceptors where signals propagate along the protein backbone from an N-terminal sensor to HAMP. We mapped the interaction surfaces of the Aer PAS, HAMP and proximal signalling domains in the kinase-off state by probing the solvent accessibility of 129 cysteine substitutions. Inaccessible PAS-HAMP surfaces overlapped with a cluster of PAS kinase-on lesions and with cysteine substitutions that crosslinked the PAS β-scaffold to the HAMP AS-2 helix. A refined Aer PAS-HAMP interaction model is presented. Compared to the kinase-off state, the kinase-on state increased the accessibility of HAMP residues (apparently relaxing PAS-HAMP interactions), but decreased the accessibility of proximal signalling domain residues. These data are consistent with an alternating static-dynamic model in which oxidized Aer-PAS interacts directly with HAMP AS-2, enforcing a static HAMP domain that in turn promotes a dynamic proximal signalling domain, resulting in a kinase-off output. When PAS-FAD is reduced, PAS interaction with HAMP is relaxed and a dynamic HAMP and static proximal signalling domain convey a kinase-on output. © 2015 John Wiley & Sons Ltd.

  17. Cell cycle phase-specific surface expression of nerve growth factor receptors TrkA and p75(NTR).

    Science.gov (United States)

    Urdiales, J L; Becker, E; Andrieu, M; Thomas, A; Jullien, J; van Grunsven, L A; Menut, S; Evan, G I; Martín-Zanca, D; Rudkin, B B

    1998-09-01

    Expression of the nerve growth factor (NGF) receptors TrkA and p75(NTR) was found to vary at the surface of PC12 cells in a cell cycle phase-specific manner. This was evidenced by using flow cytometric and microscopic analysis of cell populations labeled with antibodies to the extracellular domains of both receptors. Differential expression of these receptors also was evidenced by biotinylation of surface proteins and Western analysis, using antibodies specific for the extracellular domains of TrkA and p75(NTR). TrkA is expressed most strongly at the cell surface in M and early G1 phases, whereas p75(NTR) is expressed mainly in late G1, S, and G2 phases. This expression reflects the molecular and cellular responses to NGF in specific phases of the cell cycle; in the G1 phase NGF elicits both the anti-mitogenic effect, i.e., inhibition of the G1 to S transition, and the differentiation response whereas a survival effect is provoked elsewhere in the cell cycle. A model is proposed relating these responses to the surface expression of the two receptors. These observations open the way for novel approaches to the investigation of the mechanism of NGF signal transduction.

  18. Dynamic fluctuations of protein-carbohydrate interactions promote protein aggregation.

    Directory of Open Access Journals (Sweden)

    Vladimir Voynov

    2009-12-01

    Full Text Available Protein-carbohydrate interactions are important for glycoprotein structure and function. Antibodies of the IgG class, with increasing significance as therapeutics, are glycosylated at a conserved site in the constant Fc region. We hypothesized that disruption of protein-carbohydrate interactions in the glycosylated domain of antibodies leads to the exposure of aggregation-prone motifs. Aggregation is one of the main problems in protein-based therapeutics because of immunogenicity concerns and decreased efficacy. To explore the significance of intramolecular interactions between aromatic amino acids and carbohydrates in the IgG glycosylated domain, we utilized computer simulations, fluorescence analysis, and site-directed mutagenesis. We find that the surface exposure of one aromatic amino acid increases due to dynamic fluctuations. Moreover, protein-carbohydrate interactions decrease upon stress, while protein-protein and carbohydrate-carbohydrate interactions increase. Substitution of the carbohydrate-interacting aromatic amino acids with non-aromatic residues leads to a significantly lower stability than wild type, and to compromised binding to Fc receptors. Our results support a mechanism for antibody aggregation via decreased protein-carbohydrate interactions, leading to the exposure of aggregation-prone regions, and to aggregation.

  19. Plasmin promotes foam cell formation by increasing macrophage catabolism of aggregated low density lipoprotein

    Science.gov (United States)

    Haka, Abigail S.; Grosheva, Inna; Singh, Rajesh K.; Maxfield, Frederick R.

    2013-01-01

    Objective The plasmin/plasminogen system is involved in atherosclerosis. However, the mechanisms by which it stimulates disease are not fully defined. A key event in atherogenesis is the deposition of LDL on arterial walls where it is modified, aggregated and retained. Macrophages are recruited to clear the lipoproteins, and they become foam cells. The goal of this study was to assess the role of plasmin in macrophage uptake of aggregated LDL and foam cell formation. Approach and Results Plasminogen treatment of macrophages catabolizing aggregated LDL significantly accelerated foam cell formation. Macrophage interaction with aggregated LDL increased the surface expression of urokinase-type plasminogen activator receptor and plasminogen activator activity, resulting in increased ability to generate plasmin at the cell surface. The high local level of plasmin cleaves cell-associated aggregated LDL, allowing a portion of the aggregate to become sequestered in a nearly sealed, yet extracellular, acidic compartment. The low pH in the plasmin-induced compartment allows lysosomal enzymes, delivered via lysosome exocytosis, greater activity, resulting in more efficient cholesteryl ester hydrolysis and delivery of a large cholesterol load to the macrophage, thereby promoting foam cell formation. Conclusion These findings highlight a critical role for plasmin in the catabolism of aggregated LDL by macrophages and provide a new context for considering the atherogenic role of plasmin. PMID:23702659

  20. Plasmin promotes foam cell formation by increasing macrophage catabolism of aggregated low-density lipoprotein.

    Science.gov (United States)

    Haka, Abigail S; Grosheva, Inna; Singh, Rajesh K; Maxfield, Frederick R

    2013-08-01

    The plasmin/plasminogen system is involved in atherosclerosis. However, the mechanisms by which it stimulates disease are not fully defined. A key event in atherogenesis is the deposition of low-density lipoprotein (LDL) on arterial walls where it is modified, aggregated, and retained. Macrophages are recruited to clear the lipoproteins, and they become foam cells. The goal of this study was to assess the role of plasmin in macrophage uptake of aggregated LDL and foam cell formation. Plasminogen treatment of macrophages catabolizing aggregated LDL significantly accelerated foam cell formation. Macrophage interaction with aggregated LDL increased the surface expression of urokinase-type plasminogen activator receptor and plasminogen activator activity, resulting in increased ability to generate plasmin at the cell surface. The high local level of plasmin cleaves cell-associated aggregated LDL, allowing a portion of the aggregate to become sequestered in a nearly sealed, yet extracellular, acidic compartment. The low pH in the plasmin-induced compartment allows lysosomal enzymes, delivered via lysosome exocytosis, greater activity, resulting in more efficient cholesteryl ester hydrolysis and delivery of a large cholesterol load to the macrophage, thereby promoting foam cell formation. These findings highlight a critical role for plasmin in the catabolism of aggregated LDL by macrophages and provide a new context for considering the atherogenic role of plasmin.

  1. Identification of a response regulator involved in surface attachment, cell-cell aggregation, exopolysaccharide production and virulence in the plant pathogen Xylella fastidiosa.

    Science.gov (United States)

    Voegel, Tanja M; Doddapaneni, Harshavardhan; Cheng, Davis W; Lin, Hong; Stenger, Drake C; Kirkpatrick, Bruce C; Roper, M Caroline

    2013-04-01

    Xylella fastidiosa, the causal agent of Pierce's disease of grapevine, possesses several two-component signal transduction systems that allow the bacterium to sense and respond to changes in its environment. Signals are perceived by sensor kinases that autophosphorylate and transfer the phosphate to response regulators (RRs), which direct an output response, usually by acting as transcriptional regulators. In the X. fastidiosa genome, 19 RRs were found. A site-directed knockout mutant in one unusual RR, designated XhpT, composed of a receiver domain and a histidine phosphotransferase output domain, was constructed. The resulting mutant strain was analysed for changes in phenotypic traits related to biofilm formation and gene expression using microarray analysis. We found that the xhpT mutant was altered in surface attachment, cell-cell aggregation, exopolysaccharide (EPS) production and virulence in grapevine. In addition, this mutant had an altered transcriptional profile when compared with wild-type X. fastidiosa in genes for several biofilm-related traits, such as EPS production and haemagglutinin adhesins. © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

  2. Aggregative adherence fimbriae I (AAF/I) mediate colonization of fresh produce and abiotic surface by Shiga toxigenic enteroaggregative Escherichia coli O104:H4

    Science.gov (United States)

    The Shiga toxigenic Escherichia coli O104:H4 bares the characteristics of both enterohemorrhagic (EHEC) and enteroaggregative (EAEC) E. coli. It produces plasmid encoded aggregative adherence fimbriae I (AAF/I) which mediate cell aggregation and biofilm formation in human intestine and promote Shiga...

  3. Visual and surface plasmon resonance sensor for zirconium based on zirconium-induced aggregation of adenosine triphosphate-stabilized gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Wenjing; Zhao, Jianming [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); University of the Chinese Academy of Sciences, No. 19A Yuquanlu, Beijing 100049 (China); Zhang, Wei; Liu, Zhongyuan [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Xu, Min [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); University of the Chinese Academy of Sciences, No. 19A Yuquanlu, Beijing 100049 (China); Anjum, Saima [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); University of the Chinese Academy of Sciences, No. 19A Yuquanlu, Beijing 100049 (China); Department of Chemistry, Faculty of Science, The Islamia University of Bahawalpur, 63100 (Pakistan); Majeed, Saadat [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); University of the Chinese Academy of Sciences, No. 19A Yuquanlu, Beijing 100049 (China); Department of Chemistry, Bahauddin Zakaryia University, Multan 60800 (Pakistan); Xu, Guobao, E-mail: guobaoxu@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China)

    2013-07-17

    Graphical abstract: Visual and surface plasmon resonance (SPR) sensor for Zr(IV) has been developed for the first time based on Zr(IV)-induced change of SPR absorption spectra of ATP-stabilized AuNP solutions. -- Highlights: •Visual and SPR absorption Zr{sup 4+} sensors have been developed for the first time. •The high affinity between Zr{sup 4+} and ATP makes sensor highly sensitive and selective. •A fast response to Zr{sup 4+} within 4 min. -- Abstract: Owing to its high affinity with phosphate, Zr(IV) can induce the aggregation of adenosine 5′-triphosphate (ATP)-stabilized AuNPs, leading to the change of surface plasmon resonance (SPR) absorption spectra and color of ATP-stabilized AuNP solutions. Based on these phenomena, visual and SPR sensors for Zr(IV) have been developed for the first time. The A{sub 660} {sub nm}/A{sub 518} {sub nm} values of ATP-stabilized AuNPs in SPR absorption spectra increase linearly with the concentrations of Zr(IV) from 0.5 μM to 100 μM (r = 0.9971) with a detection limit of 95 nM. A visual Zr(IV) detection is achieved with a detection limit of 30 μM. The sensor shows excellent selectivity against other metal ions, such as Cu{sup 2+}, Fe{sup 3+}, Cd{sup 2+}, and Pb{sup 2+}. The recoveries for the detection of 5 μM, 10 μM, 25 μM and 75 μM Zr(IV) in lake water samples are 96.0%, 97.0%, 95.6% and 102.4%, respectively. The recoveries of the proposed SPR method are comparable with those of ICP-OES method.

  4. receptores

    Directory of Open Access Journals (Sweden)

    Salete Regina Daronco Benetti

    2006-01-01

    Full Text Available Se trata de un estudio etnográfico, que tuvo lo objetivo de interpretar el sistema de conocimiento y del significado atribuidos a la sangre referente a la transfusión sanguínea por los donadores y receptores de un banco de sangre. Para la colecta de las informaciones se observaron los participantes y la entrevista etnográfica se realizó el análisis de dominio, taxonómicos y temáticos. Los dominios culturales fueron: la sangre es vida: fuente de vida y alimento valioso; creencias religiosas: fuentes simbólicas de apoyos; donación sanguínea: un gesto colaborador que exige cuidarse, gratifica y trae felicidad; donación sanguínea: fuente simbólica de inseguridad; estar enfermo es una condición para realizar transfusión sanguínea; transfusión sanguínea: esperanza de vida; Creencias populares: transfusión sanguínea como riesgo para la salud; donadores de sangre: personas benditas; donar y recibir sangre: como significado de felicidad. Temática: “líquido precioso que origina, sostiene, modifica la vida, provoca miedo e inseguridad”.

  5. Down-regulation of Cell Surface Cyclic AMP Receptors and Desensitization of Cyclic AMP-stimulated Adenylate Cyclase by Cyclic AMP in Dictyostelium discoideum. Kinetics and Concentration Dependence

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1987-01-01

    cAMP binds to Dictyostelium discoideum surface receptors and induces a transient activation of adenylate cyclase, which is followed by desensitization. cAMP also induces a loss of detectable surface receptors (down-regulation). Cells were incubated with constant cAMP concentrations, washed free of

  6. Structure of Viral Aggregates

    Science.gov (United States)

    Barr, Stephen; Luijten, Erik

    2010-03-01

    The aggregation of virus particles is a particular form of colloidal self-assembly, since viruses of a give type are monodisperse and have identical, anisotropic surface charge distributions. In small-angle X-ray scattering experiments, the Qbeta virus was found to organize in different crystal structures in the presence of divalent salt and non-adsorbing polymer. Since a simple isotropic potential cannot explain the occurrence of all observed phases, we employ computer simulations to investigate how the surface charge distribution affects the virus interactions. Using a detailed model of the virus particle, we find an asymmetric ion distribution around the virus which gives rise to the different phases observed.

  7. Cell-Surface and Nuclear Receptors in the Colon as Targets for Bacterial Metabolites and Its Relevance to Colon Health

    Science.gov (United States)

    Sivaprakasam, Sathish; Bhutia, Yangzom D.; Ramachandran, Sabarish; Ganapathy, Vadivel

    2017-01-01

    The symbiotic co-habitation of bacteria in the host colon is mutually beneficial to both partners. While the host provides the place and food for the bacteria to colonize and live, the bacteria in turn help the host in energy and nutritional homeostasis, development and maturation of the mucosal immune system, and protection against inflammation and carcinogenesis. In this review, we highlight the molecular mediators of the effective communication between the bacteria and the host, focusing on selective metabolites from the bacteria that serve as messengers to the host by acting through selective receptors in the host colon. These bacterial metabolites include the short-chain fatty acids acetate, propionate, and butyrate, the tryptophan degradation products indole-3-aldehyde, indole-3-acetic, acid and indole-3-propionic acid, and derivatives of endogenous bile acids. The targets for these bacterial products in the host include the cell-surface G-protein-coupled receptors GPR41, GPR43, and GPR109A and the nuclear receptors aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR), and farnesoid X receptor (FXR). The chemical communication between these bacterial metabolite messengers and the host targets collectively has the ability to impact metabolism, gene expression, and epigenetics in colonic epithelial cells as well as in mucosal immune cells. The end result, for the most part, is the maintenance of optimal colonic health. PMID:28796169

  8. Reduced curvature of ligand-binding domain free-energy surface underlies partial agonism at NMDA receptors.

    Science.gov (United States)

    Dai, Jian; Zhou, Huan-Xiang

    2015-01-06

    NMDA receptors are ligand-gated ion channels that mediate excitatory synaptic transmission in the central nervous system. Partial agonists elicit submaximal channel activation, but crystal structures of the ligand-binding domains (LBDs) bound with partial and full agonists show little difference. To uncover the molecular mechanism for partial agonism, here we computed the free-energy surfaces of the GluN1 (an obligatory subunit of NMDA receptors) LBD bound with a variety of ligands. The free-energy minima are similarly positioned for full and partial agonists, but the curvatures are significantly reduced in the latter case, indicating higher probabilities for sampling conformations with a not fully closed domain cleft. The free-energy surfaces for antagonists have both shifted minima and further reduced curvatures. Reduced curvature of free-energy surface appears to explain well the partial agonism at NMDA receptors and may present a unique paradigm in producing graded responses for receptors in general. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Molecular recognition by a polymorphic cell surface receptor governs cooperative behaviors in bacteria.

    Directory of Open Access Journals (Sweden)

    Darshankumar T Pathak

    2013-11-01

    Full Text Available Cell-cell recognition is a fundamental process that allows cells to coordinate multicellular behaviors. Some microbes, such as myxobacteria, build multicellular fruiting bodies from free-living cells. However, how bacterial cells recognize each other by contact is poorly understood. Here we show that myxobacteria engage in recognition through interactions between TraA cell surface receptors, which leads to the fusion and exchange of outer membrane (OM components. OM exchange is shown to be selective among 17 environmental isolates, as exchange partners parsed into five major recognition groups. TraA is the determinant of molecular specificity because: (i exchange partners correlated with sequence conservation within its polymorphic PA14-like domain and (ii traA allele replacements predictably changed partner specificity. Swapping traA alleles also reprogrammed social interactions among strains, including the regulation of motility and conferred immunity from inter-strain killing. We suggest that TraA helps guide the transition of single cells into a coherent bacterial community, by a proposed mechanism that is analogous to mitochondrial fusion and fission cycling that mixes contents to establish a homogenous population. In evolutionary terms, traA functions as a rare greenbeard gene that recognizes others that bear the same allele to confer beneficial treatment.

  10. A Bacterial Surface Display System Expressing Cleavable Capsid Proteins of Human Norovirus: A Novel System to Discover Candidate Receptors

    Directory of Open Access Journals (Sweden)

    Qian Xu

    2017-12-01

    Full Text Available Human noroviruses (HuNoVs are the dominant cause of food-borne outbreaks of acute gastroenteritis. However, fundamental researches on HuNoVs, such as identification of viral receptors have been limited by the currently immature system to culture HuNoVs and the lack of efficient small animal models. Previously, we demonstrated that the recombinant protruding domain (P domain of HuNoVs capsid proteins were successfully anchored on the surface of Escherichia coli BL21 cells after the bacteria were transformed with a plasmid expressing HuNoVs P protein fused with bacterial transmembrane anchor protein. The cell-surface-displayed P proteins could specifically recognize and bind to histo-blood group antigens (HBGAs, receptors of HuNoVs. In this study, an upgraded bacterial surface displayed system was developed as a new platform to discover candidate receptors of HuNoVs. A thrombin-susceptible “linker” sequence was added between the sequences of bacterial transmembrane anchor protein and P domain of HuNoV (GII.4 capsid protein in a plasmid that displays the functional P proteins on the surface of bacteria. In this new system, the surface-displayed HuNoV P proteins could be released by thrombin treatment. The released P proteins self-assembled into small particles, which were visualized by electron microscopy. The bacteria with the surface-displayed P proteins were incubated with pig stomach mucin which contained HBGAs. The bacteria-HuNoV P proteins-HBGAs complex could be collected by low speed centrifugation. The HuNoV P proteins-HBGAs complex was then separated from the recombinant bacterial surface by thrombin treatment. The released viral receptor was confirmed by using the monoclonal antibody against type A HBGA. It demonstrated that the new system was able to capture and easily isolate receptors of HuNoVs. This new strategy provides an alternative, easier approach for isolating unknown receptors/ligands of HuNoVs from different samples

  11. Functional Homomers and Heteromers of Dopamine D2L and D3 Receptors Co-exist at the Cell Surface

    Science.gov (United States)

    Pou, Chantevy; Mannoury la Cour, Clotilde; Stoddart, Leigh A.; Millan, Mark J.; Milligan, Graeme

    2012-01-01

    Human dopamine D2long and D3 receptors were modified by N-terminal addition of SNAP or CLIP forms of O6-alkylguanine-DNA-alkyltransferase plus a peptide epitope tag. Cells able to express each of these four constructs only upon addition of an antibiotic were established and used to confirm regulated and inducible control of expression, the specificity of SNAP and CLIP tag covalent labeling reagents, and based on homogenous time-resolved fluorescence resonance energy transfer, the presence of cell surface D2long and D3 receptor homomers. Following constitutive expression of reciprocal constructs, potentially capable of forming and reporting the presence of cell surface D2long-D3 heteromers, individual clones were assessed for levels of expression of the constitutively expressed protomer. This was unaffected by induction of the partner protomer and the level of expression of the partner required to generate detectable cell surface D2long–D3 heteromers was defined. Such homomers and heteromers were found to co-exist and using a reconstitution of function approach both homomers and heteromers of D2long and D3 receptors were shown to be functional, potentially via trans-activation of associated G protein. These studies demonstrate the ability of dopamine D2long and D3 receptors to form both homomers and heteromers, and show that in cells expressing each subtype a complex mixture of homomers and heteromers co-exists at steady state. These data are of potential importance both to disorders in which D2long and D3 receptors are implicated, like schizophrenia and Parkinson disease, and also to drugs exerting their actions via these sites. PMID:22291025

  12. The mannose receptor acts as hepatitis B virus surface antigen receptor mediating interaction with intrahepatic dendritic cells

    NARCIS (Netherlands)

    Op den Brouw, Marjoleine L.; Binda, Rekha S.; Geijtenbeek, Teunis B. H.; Janssen, Harry L. A.; Woltman, Andrea M.

    2009-01-01

    Dendritic cells (DC) play a key role in anti-viral immunity. Direct interactions between DC and hepatitis B virus (HBV) may explain the impaired DC function and the ineffective anti-viral response of chronic HBV patients resulting in HBV persistence. Here, the interaction between HBV surface

  13. Urokinase plasminogen activator cleaves its cell surface receptor releasing the ligand-binding domain

    DEFF Research Database (Denmark)

    Høyer-Hansen, G; Rønne, E; Solberg, H.

    1992-01-01

    The cellular receptor for urokinase-type plasminogen activator (uPAR) is a glycolipid-anchored three-domain membrane protein playing a central role in pericellular plasminogen activation. We have found that urokinase (uPA) can cleave its receptor between domains 1 and 2 generating a cell-associat...

  14. Propranolol restricts the mobility of single EGF-receptors on the cell surface before their internalization.

    Directory of Open Access Journals (Sweden)

    Carolina Otero

    Full Text Available The epidermal growth factor receptor is involved in morphogenesis, proliferation and cell migration. Its up-regulation during tumorigenesis makes this receptor an interesting therapeutic target. In the absence of the ligand, the inhibition of phosphatidic acid phosphohydrolase activity by propranolol treatment leads to internalization of empty/inactive receptors. The molecular events involved in this endocytosis remain unknown. Here, we quantified the effects of propranolol on the mobility of single quantum-dot labelled receptors before the actual internalization took place. The single receptors showed a clear stop-and-go motion; their diffusive tracks were continuously interrupted by sub-second stalling events, presumably caused by transient clustering. In the presence of propranolol we found that: i the diffusion rate reduced by 22 %, which indicates an increase in drag of the receptor. Atomic force microscopy measurements did not show an increase of the effective membrane tension, such that clustering of the receptor remains the likely mechanism for its reduced mobility. ii The receptor got frequently stalled for longer periods of multiple seconds, which may signal the first step of the internalization process.

  15. Scavenger Receptor C-Type Lectin Binds to the Leukocyte Cell Surface Glycan Lewis By a Novel Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Feinberg, H.; Taylor, M.E.; Weis, W.I.; /Stanford U., Med. School /Imperial Coll., London

    2007-07-10

    The scavenger receptor C-type lectin (SRCL) is unique in the family of class A scavenger receptors, because in addition to binding sites for oxidized lipoproteins it also contains a C-type carbohydrate-recognition domain (CRD) that interacts with specific glycans. Both human and mouse SRCL are highly specific for the Lewis(x) trisaccharide, which is commonly found on the surfaces of leukocytes and some tumor cells. Structural analysis of the CRD of mouse SRCL in complex with Lewis(x) and mutagenesis show the basis for this specificity. The interaction between mouse SRCL and Lewis(x) is analogous to the way that selectins and DC-SIGN bind to related fucosylated glycans, but the mechanism of the interaction is novel, because it is based on a primary galactose-binding site similar to the binding site in the asialoglycoprotein receptor. Crystals of the human receptor lacking bound calcium ions reveal an alternative conformation in which a glycan ligand would be released during receptor-mediated endocytosis.

  16. The thrombopoietin receptor, c-Mpl, is a selective surface marker for human hematopoietic stem cells

    Directory of Open Access Journals (Sweden)

    Kerr William G

    2006-02-01

    Full Text Available Abstract Background Thrombopoietin (TPO, the primary cytokine regulating megakaryocyte proliferation and differentiation, exerts significant influence on other hematopoietic lineages as well, including erythroid, granulocytic and lymphoid lineages. We previously demonstrated that the receptor for TPO, c-mpl, is expressed by a subset of human adult bone marrow hematopoietic stem/progenitor cells (HSC/PC that are enriched for long-term multilineage repopulating ability in the SCID-hu Bone in vivo model of human hematopoiesis. Methods Here, we employ flow cytometry and an anti-c-mpl monoclonal antibody to comprehensively define the surface expression pattern of c-mpl in four differentiation stages of human CD34+ HSC/PC (I: CD34+38--, II: CD34+38dim, III: CD34+38+, IV: CD34dim38+ for the major sources of human HSC: fetal liver (FL, umbilical cord blood (UCB, adult bone marrow (ABM, and cytokine-mobilized peripheral blood stem cells (mPBSC. We use a surrogate in vivo model of human thymopoiesis, SCID-hu Thy/Liv, to compare the capacity of c-mpl+ vs. c-mpl-- CD34+38--/dim HSC/PC for thymocyte reconstitution. Results For all tissue sources, the percentage of c-mpl+ cells was significantly highest in stage I HSC/PC (FL 72 ± 10%, UCB 67 ± 19%, ABM 82 ± 16%, mPBSC 71 ± 15%, and decreased significantly through stages II, III, and IV ((FL 3 ± 3%, UCB 8 ± 13%, ABM 0.6 ± 0.6%, mPBSC 0.2 ± 0.1% [ANOVA: P I, decreasing through stage IV [ANOVA: P + cells [P = 0.89] or intensity of c-mpl expression [P = 0.21]. Primary Thy/Liv grafts injected with CD34+38--/dimc-mpl+ cells showed slightly higher levels of donor HLA+ thymocyte reconstitution vs. CD34+38--/dimc-mpl---injected grafts and non-injected controls (c-mpl+ vs. c-mpl--: CD2+ 6.8 ± 4.5% vs. 2.8 ± 3.3%, CD4+8-- 54 ± 35% vs. 31 ± 29%, CD4--8+ 29 ± 19% vs. 18 ± 14%. Conclusion These findings support the hypothesis that the TPO receptor, c-mpl, participates in the regulation of primitive human HSC

  17. Morphological Changes Of The Root Surface And Fracture Resistance After Treatment Of Root Fracture By CO2 Laser And Glass Ionomer Or Mineral Trioxide Aggregates

    Science.gov (United States)

    Badr, Y. A.; Abd El-Gawad, L. M.; Ghaith, M. E.

    2009-09-01

    This in vitro study evaluates the morphological changes of the root surface and fracture resistance after treatment of root cracks by CO2 laser and glass Ionomer or mineral trioxide aggregates (MTA). Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5 mm2 and a depth of 1.5 mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass Ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass Ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scanning electron microscopy was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Turkey's Honestly Significant Difference (HSD) tests. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cementum and glass Ionomer and melted masses and globular like structure between cementum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Glass Ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO2 laser increase the resistance of the teeth to fracture.

  18. Down-regulation of surface receptors for TNF and IL-1 on circulating monocytes and granulocytes during human endotoxemia: effect of neutralization of endotoxin-induced TNF activity by infusion of a recombinant dimeric TNF receptor

    NARCIS (Netherlands)

    van der Poll, T.; Coyle, S. M.; Kumar, A.; Barbosa, K.; Agosti, J. M.; Lowry, S. F.

    1997-01-01

    Leukocytes rapidly lose their surface receptors for TNF and IL-1 upon exposure to various stimuli in vitro. We sought to determine by FACS analysis changes in the expression of TNF receptors (TNFR) and type II IL-1R on circulating monocytes and granulocytes during endotoxemia in vivo, and the role

  19. Adsorption properties of p-methyl red monomeric-to-pentameric dye aggregates on anatase (101) titania surfaces: first-principles calculations of dye/TiO₂ photoanode interfaces for dye-sensitized solar cells.

    Science.gov (United States)

    Zhang, Lei; Cole, Jacqueline M

    2014-09-24

    The optical and electronic properties of dye aggregates of p-methyl red on a TiO2 anatase (101) surface were modeled as a function of aggregation order (monomer to pentameric dye) via first-principles calculations. A progressive red-shifting and intensity increase toward the visible region in UV-vis absorption spectra is observed from monomeric-to-tetrameric dyes, with each molecule in a given aggregate binding to one of the four possible TiO2 (101) adsorption sites. The pentamer exhibits a blue-shifted peak wavelength in the UV-vis absorption spectra and less absorption intensity in the visible region in comparison; a corresponding manifestation of H-aggregation occurs since one of these five molecules cannot occupy an adsorption site. This finding is consistent with experiment. Calculated density of states (DOS) and partial DOS spectra reveal similar dye···TiO2 nanocomposite conduction band characteristics but different valence band features. Associated molecular orbital distributions reveal dye-to-TiO2 interfacial charge transfer in all five differing aggregate orders; meanwhile, the level of intramolecular charge transfer in the dye becomes progressively localized around its azo- and electron-donating groups, up to the tetrameric dye/TiO2 species. Dye adsorption energies and dye coverage levels are calculated and compared with experiment. Overall, the findings of this case study serve to aid the molecular design of azo dyes toward better performing DSSC devices wherein they are incorporated. In addition, they provide a helpful example reference for understanding the effects of dye aggregation on the adsorbate···TiO2 interfacial optical and electronic properties.

  20. Adsorption Properties of p -Methyl Red Monomeric-to-Pentameric Dye Aggregates on Anatase (101) Titania Surfaces: First-Principles Calculations of Dye/TiO 2 Photoanode Interfaces for Dye-Sensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei [Cavendish; Cole, Jacqueline M. [Cavendish; Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States

    2014-08-29

    The optical and electronic properties of dye aggregates of p-methyl red on a TiO2 anatase (101) surface were modeled as a function of aggregation order (monomer to pentameric dye) via first principles calculations. A progressive red-shifting and intensity increase toward the visible region in UV/vis absorption spectra is observed from monomeric-to-tetrameric dyes, with each molecule in a given aggregate binding to one of the four possible TiO2 (101) adsorption sites. The pentamer exhibits a blue-shifted peak wave- length in the UV/vis absorption spectra and less absorption intensity in the visible region in comparison; a corresponding manifestation of H-aggregation occurs since one of these five molecules cannot occupy an adsorption site. This finding is consistent with experiment. Calculated density of states (DOS) and partial DOS spectra reveal similar dye…TiO2 nanocomposite conduction band characteristics but different valence band features. Associated molecular orbital distributions reveal dye-to-TiO2 interfacial charge transfer in all five differing aggregate orders; meanwhile, the level of intramolecular charge transfer in the dye becomes progressively localized around its azo- and electron-donating groups, up to the tetrameric dye/TiO2 species. Dye adsorption energies and dye coverage levels are calculated and compared with experiment. Overall, the findings of this case study serve to aid the molecular design of azo dyes towards better performing DSSC devices wherein they are incorporated. In addition, they provide a helpful example reference for understanding the effects of dye aggregation on the adsorbate…TiO2 interfacial optical and electronic properties.

  1. The structure and function of the urokinase receptor, a membrane protein governing plasminogen activation on the cell surface

    DEFF Research Database (Denmark)

    Behrendt, N; Rønne, E; Danø, K

    1995-01-01

    PA receptor, uPAR, is a cell-surface protein which plays an important role in the localization and regulation of these processes. In the present article a number of established conclusions concerning the structure and function of uPAR are presented, and in addition various models are discussed which might...... with the continuous identification of inhibitory reagents, this knowledge should open the possibility to interfere with the resulting, degradative events....

  2. Surface TRAIL decoy receptor-4 expression is correlated with TRAIL resistance in MCF7 breast cancer cells

    Directory of Open Access Journals (Sweden)

    Aydin Cigdem

    2005-05-01

    Full Text Available Abstract Background Tumor Necrosis Factor (TNF-Related Apoptosis-Inducing Ligand (TRAIL selectively induces apoptosis in cancer cells but not in normal cells. Despite this promising feature, TRAIL resistance observed in cancer cells seriously challenged the use of TRAIL as a death ligand in gene therapy. The current dispute concerns whether or not TRAIL receptor expression pattern is the primary determinant of TRAIL sensitivity in cancer cells. This study investigates TRAIL receptor expression pattern and its connection to TRAIL resistance in breast cancer cells. In addition, a DcR2 siRNA approach and a complementary gene therapy modality involving IKK inhibition (AdIKKβKA were also tested to verify if these approaches could sensitize MCF7 breast cancer cells to adenovirus delivery of TRAIL (Ad5hTRAIL. Methods TRAIL sensitivity assays were conducted using Molecular Probe's Live/Dead Cellular Viability/Cytotoxicity Kit following the infection of breast cancer cells with Ad5hTRAIL. The molecular mechanism of TRAIL induced cell death under the setting of IKK inhibition was revealed by Annexin V binding. Novel quantitative Real Time RT-PCR and flow cytometry analysis were performed to disclose TRAIL receptor composition in breast cancer cells. Results MCF7 but not MDA-MB-231 breast cancer cells displayed strong resistance to adenovirus delivery of TRAIL. Only the combinatorial use of Ad5hTRAIL and AdIKKβKA infection sensitized MCF7 breast cancer cells to TRAIL induced cell death. Moreover, novel quantitative Real Time RT-PCR assays suggested that while the level of TRAIL Decoy Receptor-4 (TRAIL-R4 expression was the highest in MCF7 cells, it was the lowest TRAIL receptor expressed in MDA-MB-231 cells. In addition, conventional flow cytometry analysis demonstrated that TRAIL resistant MCF7 cells exhibited substantial levels of TRAIL-R4 expression but not TRAIL decoy receptor-3 (TRAIL-R3 on surface. On the contrary, TRAIL sensitive MDA-MB-231 cells

  3. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders

    2014-01-01

    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  4. SUMOylation is required for glycine-induced increases in AMPA receptor surface expression (ChemLTP in hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Nadia Jaafari

    Full Text Available Multiple pathways participate in the AMPA receptor trafficking that underlies long-term potentiation (LTP of synaptic transmission. Here we demonstrate that protein SUMOylation is required for insertion of the GluA1 AMPAR subunit following transient glycine-evoked increase in AMPA receptor surface expression (ChemLTP in dispersed neuronal cultures. ChemLTP increases co-localisation of SUMO-1 and the SUMO conjugating enzyme Ubc9 and with PSD95 consistent with the recruitment of SUMOylated proteins to dendritic spines. In addition, we show that ChemLTP increases dendritic levels of SUMO-1 and Ubc9 mRNA. Consistent with activity dependent translocation of these mRNAs to sites near synapses, levels of the mRNA binding and dendritic transport protein CPEB are also increased by ChemLTP. Importantly, reducing the extent of substrate protein SUMOylation by overexpressing the deSUMOylating enzyme SENP-1 or inhibiting SUMOylation by expressing dominant negative Ubc9 prevent the ChemLTP-induced increase in both AMPAR surface expression and dendritic SUMO-1 mRNA. Taken together these data demonstrate that SUMOylation of synaptic protein(s involved in AMPA receptor trafficking is necessary for activity-dependent increases in AMPAR surface expression.

  5. Estrogen and androgen receptor activities of hydraulic fracturing chemicals and surface and ground water in a drilling-dense region

    Science.gov (United States)

    Kassotis, Christopher D.; Tillitt, Donald E.; Davis, J. Wade; Hormann, Anette M.; Nagel, Susan C.

    2014-01-01

    The rapid rise in natural gas extraction using hydraulic fracturing increases the potential for contamination of surface and ground water from chemicals used throughout the process. Hundreds of products containing more than 750 chemicals and components are potentially used throughout the extraction process, including more than 100 known or suspected endocrine-disrupting chemicals. We hypothesized thataselected subset of chemicalsusedin natural gas drilling operationsandalso surface and ground water samples collected in a drilling-dense region of Garfield County, Colorado, would exhibit estrogen and androgen receptor activities. Water samples were collected, solid-phase extracted, and measured for estrogen and androgen receptor activities using reporter gene assays in human cell lines. Of the 39 unique water samples, 89%, 41%, 12%, and 46% exhibited estrogenic, antiestrogenic, androgenic, and antiandrogenic activities, respectively. Testing of a subset of natural gas drilling chemicals revealed novel antiestrogenic, novel antiandrogenic, and limited estrogenic activities. The Colorado River, the drainage basin for this region, exhibited moderate levels of estrogenic, antiestrogenic, and antiandrogenic activities, suggesting that higher localized activity at sites with known natural gas–related spills surrounding the river might be contributing to the multiple receptor activities observed in this water source. The majority of water samples collected from sites in a drilling-dense region of Colorado exhibited more estrogenic, antiestrogenic, or antiandrogenic activities than reference sites with limited nearby drilling operations. Our data suggest that natural gas drilling operationsmayresult in elevated endocrine-disrupting chemical activity in surface and ground water.

  6. SCALE FOR CONSTRUCTIVE AGGREGATION

    OpenAIRE

    Sujitha Mary; Alaguraj, V.; Krishnaswamy, S

    2014-01-01

    Aggregation is an inherent property of proteins. Both ordered and disordered proteins have a tendency to aggregate. Protein folding itself starts from the partially folded intermediates. The formation of native structures from these intermediates may be called as constructive aggregation. We describe the design of an intrinsic aggregation scale and its efficiency in finding hot-spots for constructive aggregation. In this paper, we are proposing a new aspect of aggregation, wherein...

  7. The growth-defense pivot: Crisis management in plants mediated by LRR-RK surface receptors

    Science.gov (United States)

    Belkhadir, Youssef; Yang, Li; Hetzel, Jonathan; Dangl, Jeffery L.; Chory, Joanne

    2014-01-01

    Plants must adapt to their environment and require mechanisms for sensing their surroundings and responding appropriately. An expanded family of greater than 200 leucine-rich repeat receptor kinases (LRR-RKs) transduces fluctuating and often contradictory signals from the environment into changes in nuclear gene expression. Two LRR-RKs, BRASSINOSTEROID INSENSITIVE 1 (BRI1), a steroid receptor, and FLAGELLIN-SENSITIVE 2 (FLS2), an innate immune receptor that recognizes bacterial flagellin, act cooperatively to partition necessary growth-defense tradeoffs. BRI1 and FLS2 share common signaling components and slightly different activation mechanisms. BRI1 and FLS2 are paradigms for understanding signaling mechanisms of LRR-containing receptors in plants. PMID:25089011

  8. Role of multicellular aggregates in biofilm formation

    DEFF Research Database (Denmark)

    Kragh, Kasper N.; Hutchison, Jaime B.; Melaugh, Gavin

    2016-01-01

    In traditional models of in vitro biofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However......, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm...... initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development of Pseudomonas aeruginosa biofilms. We find that the relative fitness of aggregates depends...

  9. Early Alterations in Ovarian Surface Epithelial Cells and Induction of Ovarian Epithelial Tumors Triggered by Loss of FSH Receptor

    Directory of Open Access Journals (Sweden)

    Xinlei Chen

    2007-06-01

    Full Text Available Little is known about the behavior of the ovarian surface epithelium (OSE, which plays a central role in ovarian cancer etiology. It has been suggested that incessant ovulation causes OSE changes leading to transformation and that high gonadotropin levels during postmenopause activate OSE receptors, inducing proliferation. We examined the chronology of OSE changes, including tumor appearance, in a mouse model where ovulation never occurs due to deletion of follitropin receptor. Changes in epithelial cells were marked by pan-cytokeratin (CK staining. Histologic changes and CK staining in the OSE increased from postnatal day 2. CK staining was observed inside the ovary by 24 days and increased thereafter in tumor-bearing animals. Ovaries from a third of aged (1 year mutant mice showed CK deep inside, indicating cell migration. These tumors resembled serous papillary adenoma of human ovaries. Weak expression of GATA-4 and elevation of PCNA, cyclooxygenase-1, cyclooxygenase-2, and plateletderived growth factor receptors α and β in mutants indicated differences in cell proliferation, differentiation, and inflammation. Thus, we report that OSE changes occur long before epithelial tumors appear in FORKO mice. Our results suggest that neither incessant ovulation nor follicle-stimulating hormone receptor presence in the OSE is required for inducing ovarian tumors; thus, other mechanisms must contribute to ovarian tumorigenesis.

  10. Making Graphene Resist Aggregation

    Science.gov (United States)

    Luo, Jiayan

    Graphene-based sheets have stimulated great interest in many scientific disciplines and shown promise for wide potential applications. Among various ways of creating single atomic layer carbon sheets, a promising route for bulk production is to first chemically exfoliate graphite powders to graphene oxide (GO) sheets, followed by reduction to form chemically modified graphene (CMG). Due to the strong van der Waals attraction between graphene sheets, CMG tends to aggregate. The restacking of sheets is largely uncontrollable and irreversible, thus it reduces their processability and compromises properties such as accessible surface area. Strategies based on colloidal chemistry have been applied to keep CMG dispersed in solvents by introducing electrostatic repulsion to overcome the van der Waals attraction or adding spacers to increase the inter-sheet spacing. In this dissertation, two very different ideas that can prevent CMG aggregation without extensively modifying the material or introducing foreign spacer materials are introduced. The van der Waals potential decreases with reduced overlapping area between sheets. For CMG, reducing the lateral dimension from micrometer to nanometer scale should greatly enhance their colloidal stability with additional advantages of increased charge density and decreased probability to interact. The enhanced colloidal stability of GO and CMG nanocolloids makes them especially promising for spectroscopy based bio-sensing applications. For potential applications in a compact bulk solid form, the sheets were converted into paper-ball like structure using capillary compression in evaporating aerosol droplets. The crumpled graphene balls are stabilized by locally folded pi-pi stacked ridges, and do not unfold or collapse during common processing steps. They can tightly pack without greatly reducing the surface area. This form of graphene leads to scalable performance in energy storage. For example, planer sheets tend to aggregate and

  11. Effect of spatial inhomogeneities on the membrane surface on receptor dimerization and signal initiation

    Directory of Open Access Journals (Sweden)

    Romica Kerketta

    2016-08-01

    Full Text Available Important signal transduction pathways originate on the plasma membrane, where microdomains may transiently entrap diffusing receptors. This results in a non-random distribution of receptors even in the resting state, which can be visualized as clusters by high resolution imaging methods. Here, we explore how spatial in-homogeneities in the plasma membrane might influence the dimerization and phosphorylation status of ErbB2 and ErbB3, two receptor tyrosine kinases that preferentially heterodimerize and are often co-expressed in cancer. This theoretical study is based upon spatial stochastic simulations of the two-dimensional membrane landscape, where variables include differential distributions and overlap of transient confinement zones (domains for the two receptor species. The in silico model is parameterized and validated using data from single particle tracking experiments. We report key differences in signaling output based on the degree of overlap between domains and the relative retention of receptors in such domains, expressed as escape probability. Results predict that a high overlap of domains, which favors transient co-confinement of both receptor species, will enhance the rate of hetero-interactions. Where domains do not overlap, simulations confirm expectations that homo-interactions are favored. Since ErbB3 is uniquely dependent on ErbB2 interactions for activation of its catalytic activity, variations in domain overlap or escape probability markedly alter the predicted patterns and time course of ErbB3 and ErbB2 phosphorylation. Taken together, these results implicate membrane domain organization as an important modulator of signal initiation, motivating the design of novel experimental approaches to measure these important parameters across a wider range of receptor systems.

  12. Engineering of PDMS surfaces for use in microsystems for capture and isolation of complex and biomedically important proteins: epidermal growth factor receptor as a model system.

    Science.gov (United States)

    Lowe, Aaron M; Ozer, Byram H; Wiepz, Gregory J; Bertics, Paul J; Abbott, Nicholas L

    2008-08-01

    Elastomers based on poly(dimethylsiloxane) (PDMS) are promising materials for fabrication of a wide range of microanalytical systems due to their mechanical and optical properties and ease of processing. To date, however, quantitative studies that demonstrate reliable and reproducible methods for attachment of binding groups that capture complex receptor proteins of relevance to biomedical applications of PDMS microsystems have not been reported. Herein we describe methods that lead to the reproducible capture of a transmembrane protein, the human epidermal growth factor (EGF) receptor, onto PDMS surfaces presenting covalently immobilized antibodies for EGF receptor, and subsequent isolation of the captured receptor by mechanical transfer of the receptor onto a chemically functionalized surface of a gold film for detection. This result is particularly significant because the physical properties of transmembrane proteins make this class of proteins a difficult one to analyze. We benchmark the performance of antibodies to the human EGF receptor covalently immobilized on PDMS against the performance of the same antibodies physisorbed to conventional surfaces utilized in ELISA assays through the use of EGF receptor that was (32)P-radiolabeled in its autophosphorylation domain. These results reveal that two pan-reactive antibodies for the EGF receptor (clones H11 and 111.6) and one phosphospecific EGF receptor antibody (clone pY1068) capture the receptor on both PDMS and ELISA plates. When using H11 antibody to capture EGF receptor and subsequent treatment with a stripping buffer (NaOH and sodium dodecylsulfate) to isolate the receptor, the signal-to-background obtained using the PDMS surface was 82 : 1, exceeding the signal-to-background measured on the ELISA plate (<48 : 1). We also characterized the isolation of captured EGF receptor by mechanical contact of the PDMS surface with a chemically functionalized gold film. The efficiency of mechanical transfer of the

  13. 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

  14. Sulforaphane prevents human platelet aggregation through inhibiting the phosphatidylinositol 3-kinase/Akt pathway.

    Science.gov (United States)

    Chuang, Wen-Ying; Kung, Po-Hsiung; Kuo, Chih-Yun; Wu, Chin-Chung

    2013-06-01

    Sulforaphane, a dietary isothiocyanate found in cruciferous vegetables, has been shown to exert beneficial effects in animal models of cardiovascular diseases. However, its effect on platelet aggregation, which is a critical factor in arterial thrombosis, is still unclear. In the present study, we show that sulforaphane inhibited human platelet aggregation caused by different receptor agonists, including collagen, U46619 (a thromboxane A2 mimic), protease-activated receptor 1 agonist peptide (PAR1-AP), and an ADP P2Y12 receptor agonist. Moreover, sulforaphane significantly reduced thrombus formation on a collagen-coated surface under whole blood flow conditions. In exploring the underlying mechanism, we found that sulforaphane specifically prevented phosphatidylinositol 3-kinase (PI3K)/Akt signalling, without markedly affecting other signlaling pathways involved in platelet aggregation, such as protein kinase C activation, calcium mobilisation, and protein tyrosine phosphorylation. Although sulforaphane did not directly inhibit the catalytic activity of PI3K, it caused ubiquitination of the regulatory p85 subunit of PI3K, and prevented PI3K translocation to membranes. In addition, sulforaphane caused ubiquitination and degradation of phosphoinositide-dependent kinase 1 (PDK1), which is required for Akt activation. Therefore, sulforaphane is able to inhibit the PI3K/Akt pathway at two distinct sites. In conclusion, we have demonstrated that sulforaphane prevented platelet aggregation and reduced thrombus formation in flow conditions; our data also support that the inhibition of the PI3K/Akt pathway by sulforaphane contributes it antiplatelet effects.

  15. A C1q domain containing protein from scallop Chlamys farreri serving as pattern recognition receptor with heat-aggregated IgG binding activity.

    Directory of Open Access Journals (Sweden)

    Leilei Wang

    Full Text Available BACKGROUND: The C1q domain containing (C1qDC proteins refer to a family of all proteins that contain the globular C1q (gC1q domain, and participate in a series of immune responses depending on their gC1q domains to bind a variety of self and non-self binding ligands. METHODOLOGY: In the present study, the mRNA expression patterns, localization, and activities of a C1qDC protein from scallop Chlamys farreri (CfC1qDC were investigated to understand its possible functions in innate immunity. The relative expression levels of CfC1qDC mRNA in hemocytes were all significantly up-regulated after four typical PAMPs (LPS, PGN, β-glucan and polyI:C stimulation. During the embryonic development of scallop, the mRNA transcripts of CfC1qDC were detected in all the stages, and the expression level was up-regulated from D-hinged larva and reached the highest at eye-spot larva. The endogenous CfC1qDC was dominantly located in the hepatopancreas, gill, kidney and gonad of adult scallop through immunofluorescence. The recombinant protein of CfC1qDC (rCfC1qDC could not only bind various PAMPs, such as LPS, PGN, β-glucan as well as polyI:C, but also enhance the phagocytic activity of scallop hemocytes towards Escherichia coli. Meanwhile, rCfC1qDC could interact with human heat-aggregated IgG, and this interaction could be inhibited by LPS. CONCLUSIONS: All these results indicated that CfC1qDC in C. farreri not only served as a PRR involved in the PAMPs recognition, but also an opsonin participating in the clearance of invaders in innate immunity. Moreover, the ability of CfC1qDC to interact with immunoglobulins provided a clue to understand the evolution of classical pathway in complement system.

  16. Targeting cell surface receptors for axon regeneration in the central nervous system

    Directory of Open Access Journals (Sweden)

    Menghon Cheah

    2016-01-01

    Full Text Available Axon regeneration in the CNS is largely unsuccessful due to excess inhibitory extrinsic factors within lesion sites together with an intrinsic inability of neurons to regrow following injury. Recent work demonstrates that forced expression of certain neuronal transmembrane receptors can recapitulate neuronal growth resulting in successful growth within and through inhibitory lesion environments. More specifically, neuronal expression of integrin receptors such as alpha9beta1 integrin which binds the extracellular matrix glycoprotein tenascin-C, trk receptors such as trkB which binds the neurotrophic factor BDNF, and receptor PTPσ which binds chondroitin sulphate proteoglycans, have all been show to significantly enhance regeneration of injured axons. We discuss how reintroduction of these receptors in damaged neurons facilitates signalling from the internal environment of the cell with the external environment of the lesion milieu, effectively resulting in growth and repair following injury. In summary, we suggest an appropriate balance of intrinsic and extrinsic factors are required to obtain substantial axon regeneration.

  17. Antibodies against amino acids 1-15 of tumor necrosis factor block its binding to cell-surface receptor.

    OpenAIRE

    Socher, S H; Riemen, M W; Martinez, D; Friedman, A; Tai, J; Quintero, J C; Garsky, V; Oliff, A

    1987-01-01

    Human tumor necrosis factor (hTNF) mediates a variety of biologic activities, which are dependent on the attachment of hTNF to cell-surface receptors. To identify regions of the hTNF protein involved in binding hTNF to its receptor, we prepared five synthetic peptides [hTNF-(1-15), hTNF-(1-31), hTNF-(65-79), hTNF-(98-111), and hTNF-(124-141)] and two hydroxylamine cleavage fragments [hTNF-(1-39) and hTNF-(40-157)] of hTNF. The hTNF-synthetic peptides and hTNF fragments were tested in hTNF rec...

  18. Ligand-specific regulation of the extracellular surface of a G-protein-coupled receptor

    DEFF Research Database (Denmark)

    Bokoch, Michael P; Zou, Yaozhong; Rasmussen, Søren Gøgsig Faarup

    2010-01-01

    G-protein-coupled receptors (GPCRs) are seven-transmembrane proteins that mediate most cellular responses to hormones and neurotransmitters. They are the largest group of therapeutic targets for a broad spectrum of diseases. Recent crystal structures of GPCRs have revealed structural conservation...... receptor: a salt bridge linking extracellular loops 2 and 3. Small-molecule drugs that bind within the transmembrane core and exhibit different efficacies towards G-protein activation (agonist, neutral antagonist and inverse agonist) also stabilize distinct conformations of the ECS. We thereby demonstrate...

  19. Evidence for the involvement of complement proteins in platelet aggregation by Streptococcus sanguis NCTC 7863.

    Science.gov (United States)

    Ford, I; Douglas, C W; Heath, J; Rees, C; Preston, F E

    1996-09-01

    We investigated the mechanisms of platelet aggregation by the type strain of Streptococcus sanguis (NCTC 7863). This species is one of the major aetiological agents of infective endocarditis. S. sanguis NCTC 7863 caused aggregation of normal human platelets in vitro following a lag period that varied between donors (7-19 min). Platelet aggregation was dependent on one or more plasma constituents and all the necessary factors gradually became bound to the bacterial surface during the lag period. The length of the lag period was determined by the plasma of the donor and not by a feature of their platelets. Platelet aggregation by S. sanguis NCTC 7863 could be inhibited by heating plasma at 56 degrees C, by treating plasma with cobra venom factor, or by incubating with soluble Complement Receptor 1, all of which inhibit or deplete complement. Complement activation required Mg2+, but not Ca2+ ions and the the cleavage fragment, Ba, of factor B was produced, indicating that the alternative pathway was operative. Zymosan- and S. sanguis-induced aggregation showed similarities, including the same variability in lag times among donors, and absorption of plasma with zymosan prevented the plasma from supporting platelet aggregation by S. sanguis, C3, C9 and vitronectin were found to bind to S. sanguis NCTC 7863, but the latter two were present at very low levels on a non-aggregating strain of S. sanguis, SK96. The rate of assembly of the C5b-9 complex on the NCTC 7863 bacterial surface correlated with the lag time. These data suggest a role for the complement pathway in platelet aggregation by the type strain of S. sanguis.

  20. Aggregation of sponge cells. XIV. Possible substitution of calcium ions by polycations.

    Science.gov (United States)

    Müller, W E; Zahn, R K; Kurelec, B; Müller, I

    1978-05-01

    Single cells from the siliceous sponge Geodia cydonium, obtained after chemical dissociation, reaggregate in the presence of the aggregation factor in Ca2+-containing medium to large aggregates. It was found that polyvalent organic cations (polylysine, spermine, spermidine, putrescine) enhance the Ca2+-mediated cell aggregation. In Ca2+-free medium these compounds also cause reaggregation; aggregates of a diameter up to 800 micron are formed within 120 min. Proteins, containing basic groups of amino acid residues have no influence on cell aggregation. Monovalent cations inhibit the reaggregation process. The enhancing effect of polyvalent organic cations on cell aggregation is dependent on the presence of the soluble aggregation factor. From the findings that polycations do not alter the duration of the lag phase (a characteristic of the aggregation factor-mediated Geodia cell reaggregation) and act in cooperation with the aggregation receptor, we assume that the polycations bind between the aggregation factor and the aggregation receptor.

  1. CARbodies: Human Antibodies Against Cell Surface Tumor Antigens Selected From Repertoires Displayed on T Cell Chimeric Antigen Receptors

    Directory of Open Access Journals (Sweden)

    Vanesa Alonso-Camino

    2013-01-01

    Full Text Available A human single-chain variable fragment (scFv antibody library was expressed on the surface of human T cells after transduction with lentiviral vectors (LVs. The repertoire was fused to a first-generation T cell receptor ζ (TCRζ-based chimeric antigen receptor (CAR. We used this library to isolate antibodies termed CARbodies that recognize antigens expressed on the tumor cell surface in a proof-of-principle system. After three rounds of activation-selection there was a clear repertoire restriction, with the emergence dominant clones. The CARbodies were purified from bacterial cultures as soluble and active proteins. Furthermore, to validate its potential application for adoptive cell therapy, human T cells were transduced with a LV encoding a second-generation costimulatory CAR (CARv2 bearing the selected CARbodies. Transduced human primary T cells expressed significant levels of the CARbodies-based CARv2 fusion protein on the cell surface, and importantly could be specifically activated, after stimulation with tumor cells. This approach is a promising tool for the generation of antibodies fully adapted to the display format (CAR and the selection context (cell synapse, which could extend the scope of current adoptive cell therapy strategies with CAR-redirected T cells.

  2. Receptor Surface Models in the Classroom: Introducing Molecular Modeling to Students in a 3-D World

    Science.gov (United States)

    Geldenhuys, Werner J.; Hayes, Michael; Van der Schyf, Cornelis J.; Allen, David D.; Malan, Sarel F.

    2007-01-01

    A simple, novel and generally applicable method to demonstrate structure-activity associations of a group of biologically interesting compounds in relation to receptor binding is described. This method is useful for undergraduates and graduate students in medicinal chemistry and computer modeling programs.

  3. A vertically resolved model for phytoplankton aggregation

    Indian Academy of Sciences (India)

    Simple experiments demonstrate the effects of aggregation on the timing and depth distribution of primary production and export. A more detailed ecological model is applied to sites in the Arabian Sea; it demonstrates that aggregation can be important for deep sedimentation even when its effect on surface concentrations ...

  4. Positive Charges on the Surface of Thaumatin Are Crucial for the Multi-Point Interaction with the Sweet Receptor

    Directory of Open Access Journals (Sweden)

    Tetsuya Masuda

    2018-02-01

    Full Text Available Thaumatin, an intensely sweet-tasting protein, elicits sweet taste with a threshold of only 50 nM. Previous studies from our laboratory suggested that the complex model between the T1R2-T1R3 sweet receptor and thaumatin depends critically on the complementarity of electrostatic potentials. In order to further validate this model, we focused on three lysine residues (Lys78, Lys106, and Lys137, which were expected to be part of the interaction sites. Three thaumatin mutants (K78A, K106A, and K137A were prepared and their threshold values of sweetness were examined. The results showed that the sweetness of K106A was reduced by about three times and those of K78A and K137A were reduced by about five times when compared to wild-type thaumatin. The three-dimensional structures of these mutants were also determined by X-ray crystallographic analyses at atomic resolutions. The overall structures of mutant proteins were similar to that of wild-type but the electrostatic potentials around the mutated sites became more negative. Since the three lysine residues are located in 20–40 Å apart each other on the surface of thaumatin molecule, these results suggest the positive charges on the surface of thaumatin play a crucial role in the interaction with the sweet receptor, and are consistent with a large surface is required for interaction with the sweet receptor, as proposed by the multipoint interaction model named wedge model.

  5. Interactions between a receptor tyrosine phosphatase and a cell surface ligand regulate axon guidance and glial-neuronal communication.

    Science.gov (United States)

    Lee, Hyung-Kook Peter; Cording, Amy; Vielmetter, Jost; Zinn, Kai

    2013-06-05

    We developed a screening method for orphan receptor ligands, in which cell-surface proteins are expressed in Drosophila embryos from GAL4-dependent insertion lines and ligand candidates identified by the presence of ectopic staining with receptor fusion proteins. Stranded at second (Sas) binds to the receptor tyrosine phosphatase Ptp10D in embryos and in vitro. Sas and Ptp10D can interact in trans when expressed in cultured cells. Interactions between Sas and Ptp10D on longitudinal axons are required to prevent them from abnormally crossing the midline. Sas is expressed on both neurons and glia, whereas Ptp10D is restricted to CNS axons. We conducted epistasis experiments by overexpressing Sas in glia and examining how the resulting phenotypes are changed by removal of Ptp10D from neurons. We find that neuronal Ptp10D restrains signaling by overexpressed glial Sas, which would otherwise produce strong glial and axonal phenotypes. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Conserved cysteine residues in the extracellular loop of the human P2X(1) receptor form disulfide bonds and are involved in receptor trafficking to the cell surface

    National Research Council Canada - National Science Library

    Ennion, Steven J; Evans, Richard J

    2002-01-01

    P2X receptors contain 10 conserved cysteines in the extracellular loop. To investigate whether these residues form disulfide bonds, we created a series of single and double cysteine-alanine mutants in the human P2X(1) receptor...

  7. Conserved Cysteine Residues in the Extracellular Loop of the Human P2X1 Receptor Form Disulfide Bonds and Are Involved in Receptor Trafficking to the Cell Surface

    National Research Council Canada - National Science Library

    Steven J. Ennion; Richard J. Evans

    2002-01-01

    P2X receptors contain 10 conserved cysteines in the extracellular loop. To investigate whether these residues form disulfide bonds, we created a series of single and double cysteine-alanine mutants in the human P2X 1 receptor...

  8. Aggregation of human platelets and adhesion of Streptococcus sanguis.

    Science.gov (United States)

    Herzberg, M C; Brintzenhofe, K L; Clawson, C C

    1983-01-01

    Platelet vegetations or thrombi are common findings in subacute bacterial endocarditis. We investigated the hypothesis that human platelets selectively bind or adhere strains of Streptococcus sanguis and Streptococcus mutans and aggregate, as a result, into an in vitro thrombus. Earlier ultrastructural studies suggested that aggregation of platelets over time by Staphylococcus aureus was preceded in order by adhesion and platelet activation. We uncoupled the adhesion step from activation and aggregation in our studies by incubating streptococci with platelet ghosts in a simple, quantitative assay. Adhesion was shown to be mediated by protease-sensitive components on the streptococci and platelet ghosts rather than cell surface carbohydrates or dextrans, plasma components, or divalent cations. The same streptococci were also studied by standard aggregometry techniques. Platelet-rich plasma was activated and aggregated by certain isolates of S. sanguis. Platelet ghosts bound the same strains selectively under Ca2+- and plasma-depleted conditions. Fresh platelets could activate after washing, but Ca2+ had to be restored. Aggregation required fresh platelets in Ca2+-restored plasma and was inducible by washed streptococcal cell walls. These reactions in the binding and aggregometry assays were confirmed by transmission electron microscopy. Surface microfibrils on intact S. sanguis were identified. These appendages appeared to bind S. sanguis to platelets. The selectivity of adhesion of the various S. sanguis strains to platelet ghosts or Ca2+- and plasma-depleted fresh washed platelets was similar for all donors. Thus, the platelet binding site was expressed widely in the population and was unlikely to be an artifact of membrane aging or preparation. Since selective adhesion of S. sanguis to platelets was apparently required for aggregation, it is suggested that functionally defined receptors for ligands on certain strains of S. sanguis may be present on human

  9. Neuraminidase-1, a Subunit of the Cell Surface Elastin Receptor, Desialylates and Functionally Inactivates Adjacent Receptors Interacting with the Mitogenic Growth Factors PDGF-BB and IGF-2

    Science.gov (United States)

    Hinek, Aleksander; Bodnaruk, Tetyana D.; Bunda, Severa; Wang, Yanting; Liu, Kela

    2008-01-01

    We recently established that the elastin-binding protein, which is identical to the spliced variant of β-galactosidase, forms a cell surface-targeted complex with two proteins considered “classic lysosomal enzymes”: protective protein/cathepsin A and neuraminidase-1 (Neu1). We also found that cell surface-residing Neu1 can desialylate neighboring microfibrillar glycoproteins and facilitate the deposition of insoluble elastin, which contributes to the maintenance of cellular quiescence. Here we provide evidence that cell surface-residing Neu1 contributes to a novel mechanism that limits cellular proliferation by desialylating cell membrane-residing sialoglycoproteins that directly propagate mitogenic signals. We demonstrated that treatment of cultured human aortic smooth muscle cells (SMCs) with either a sialidase inhibitor or an antibody that blocks Neu1 activity induced significant up-regulation in SMC proliferation in response to fetal bovine serum. Conversely, treatment with Clostridium perfringens neuraminidase (which is highly homologous to Neu1) decreased SMC proliferation, even in cultures that did not deposit elastin. Further, we found that pretreatment of aortic SMCs with exogenous neuraminidase abolished their mitogenic responses to recombinant platelet-derived growth factor (PDGF)-BB and insulin-like growth factor (IGF)-2 and that sialidosis fibroblasts (which are exclusively deficient in Neu1) were more responsive to PDGF-BB and IGF-2 compared with normal fibroblasts. Furthermore, we provide direct evidence that neuraminidase caused the desialylation of both PDGF and IGF-1 receptors and diminished the intracellular signals induced by the mitogenic ligands PDGF-BB and IGF-2. PMID:18772331

  10. Shaping the Growth Behaviour of Bacterial Aggregates in Biofilms

    CERN Document Server

    Melaugh, Gavin; Kragh, Kasper Nørskov; Irie, Yasuhiko; Roberts, Aled; Bjarnsholt, Thomas; Diggle, Steve P; Gordon, Vernita; Allen, Rosalind J

    2015-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase meaning it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the role of aggregate shape, we find that the degree of spreading of an aggregate on a surface can play a key role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding bacterial cells is low, while initially rounded aggregates perform better when competition is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the...

  11. In vivo stem cell tracking with imageable nanoparticles that bind bioorthogonal chemical receptors on the stem cell surface.

    Science.gov (United States)

    Lee, Sangmin; Yoon, Hwa In; Na, Jin Hee; Jeon, Sangmin; Lim, Seungho; Koo, Heebeom; Han, Sang-Soo; Kang, Sun-Woong; Park, Soon-Jung; Moon, Sung-Hwan; Park, Jae Hyung; Cho, Yong Woo; Kim, Byung-Soo; Kim, Sang Kyoon; Lee, Taekwan; Kim, Dongkyu; Lee, Seulki; Pomper, Martin G; Kwon, Ick Chan; Kim, Kwangmeyung

    2017-09-01

    It is urgently necessary to develop reliable non-invasive stem cell imaging technology for tracking the in vivo fate of transplanted stem cells in living subjects. Herein, we developed a simple and well controlled stem cell imaging method through a combination of metabolic glycoengineering and bioorthogonal copper-free click chemistry. Firstly, the exogenous chemical receptors containing azide (-N3) groups were generated on the surfaces of stem cells through metabolic glycoengineering using metabolic precursor, tetra-acetylated N-azidoacetyl-d-mannosamine(Ac4ManNAz). Next, bicyclo[6.1.0]nonyne-modified glycol chitosan nanoparticles (BCN-CNPs) were prepared as imageable nanoparticles to deliver different imaging agents. Cy5.5, iron oxide nanoparticles and gold nanoparticles were conjugated or encapsulated to BCN-CNPs for optical, MR and CT imaging, respectively. These imageable nanoparticles bound chemical receptors on the Ac4ManNAz-treated stem cell surface specifically via bioorthogonal copper-free click chemistry. Then they were rapidly taken up by the cell membrane turn-over mechanism resulting in higher endocytic capacity compared non-specific uptake of nanoparticles. During in vivo animal test, BCN-CNP-Cy5.5-labeled stem cells could be continuously tracked by non-invasive optical imaging over 15 days. Furthermore, BCN-CNP-IRON- and BCN-CNP-GOLD-labeled stem cells could be efficiently visualized using in vivo MR and CT imaging demonstrating utility of our stem cell labeling method using chemical receptors. These results conclude that our method based on metabolic glycoengineering and bioorthogonal copper-free click chemistry can stably label stem cells with diverse imageable nanoparticles representing great potential as new stem cell imaging technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Prostaglandin E receptor subtype EP3 expression in human conjunctival epithelium and its changes in various ocular surface disorders.

    Directory of Open Access Journals (Sweden)

    Mayumi Ueta

    Full Text Available BACKGROUND: In our earlier genome-wide association study on Stevens-Johnson Syndrome (SJS and its severe variant, toxic epidermal necrolysis (TEN, we found that in Japanese patients with these severe ocular surface complications there was an association with prostaglandin E receptor 3 (EP3 gene (PTGER3 polymorphisms. We also reported that EP3 is dominantly expressed in the ocular surface-, especially the conjunctival epithelium, and suggested that EP3 in the conjunctival epithelium may down-regulate ocular surface inflammation. In the current study we investigated the expression of EP3 protein in the conjunctiva of patients with various ocular surface diseases such as SJS/TEN, chemical eye burns, Mooren's ulcers, and ocular cicatricial pemphigoid (OCP. METHODOLOGY/PRINCIPAL FINDINGS: Conjunctival tissues were obtained from patients undergoing surgical reconstruction of the ocular surface due to SJS/TEN, chemical eye burns, and OCP, and from patients with Mooren's ulcers treated by resection of the inflammatory conjunctiva. The controls were nearly normal human conjunctival tissues acquired at surgery for conjunctivochalasis. We performed immunohistological analysis of the EP3 protein and evaluated the immunohistological staining of EP3 protein in the conjunctival epithelium of patients with ocular surface diseases. EP3 was expressed in the conjunctival epithelium of patients with chemical eye burns and Mooren's ulcer and in normal human conjunctival epithelium. However, it was markedly down-regulated in the conjunctival epithelium of SJS/TEN and OCP patients. CONCLUSIONS: We posit an association between the down-regulation of EP3 in conjunctival epithelium and the pathogenesis and pathology of SJS/TEN and OCP, and suggest a common mechanism(s in the pathology of these diseases. The examination of EP3 protein expression in conjunctival epithelium may aid in the differential diagnosis of various ocular surface diseases.

  13. Thermodynamics of Protein Aggregation

    Science.gov (United States)

    Osborne, Kenneth L.; Barz, Bogdan; Bachmann, Michael; Strodel, Birgit

    Amyloid protein aggregation characterizes many neurodegenerative disorders, including Alzheimer's, Parkinson's, and Creutz- feldt-Jakob disease. Evidence suggests that amyloid aggregates may share similar aggregation pathways, implying simulation of full-length amyloid proteins is not necessary for understanding amyloid formation. In this study we simulate GNNQQNY, the N-terminal prion-determining domain of the yeast protein Sup35 to investigate the thermodynamics of structural transitions during aggregation. We use a coarse-grained model with replica-exchange molecular dynamics to investigate the association of 3-, 6-, and 12-chain GNNQQNY systems and we determine the aggregation pathway by studying aggregation states of GN- NQQNY. We find that the aggregation of the hydrophilic GNNQQNY sequence is mainly driven by H-bond formation, leading to the formation of /3-sheets from the very beginning of the assembly process. Condensation (aggregation) and ordering take place simultaneously, which is underpinned by the occurrence of a single heat capacity peak only.

  14. Heating Techniques for Asphalt/Aggregate Mixtures.

    Science.gov (United States)

    1979-12-01

    gravel, and rock, as well as materials that require both crushing and screening, such as limestone and granite. In no case may the aggregate particles...the aggregate surfaces and the cementing action of the bitumen. PLANT-MIX HOT-LAID BITUMINOUS SURFACES Hot-mix bituminous concrete is Composed of...well-graded mineral aggre- gates, mineral filler , and bituminous material (AC or tar, depending on the 4 desired mixture). The hot-mix method of

  15. M-CSF receptor mutations in hereditary diffuse leukoencephalopathy with spheroids impair not only kinase activity but also surface expression

    Energy Technology Data Exchange (ETDEWEB)

    Hiyoshi, Masateru; Hashimoto, Michihiro; Yukihara, Mamiko; Bhuyan, Farzana; Suzu, Shinya, E-mail: ssuzu06@kumamoto-u.ac.jp

    2013-11-01

    Highlights: •Many mutations were identified in Fms as a putative genetic cause of HDLS. •All of the mutations tested severely impair the kinase activity. •Most of the mutations also impair the trafficking to the cell surface. •These defects further suggest that HDLS is caused by a loss of Fms function. -- Abstract: The tyrosine kinase Fms, the cell surface receptor for M-CSF and IL-34, is critical for microglial proliferation and differentiation in the brain. Recently, a number of mutations have been identified in Fms as a putative genetic cause of hereditary diffuse leukoencephalopathy with spheroids (HDLS), implying an important role of microglial dysfunction in HDLS pathogenesis. In this study, we initially confirmed that 11 mutations, which reside within the ATP-binding or major tyrosine kinase domain, caused a severe impairment of ligand-induced Fms auto-phosphorylation. Intriguingly, we found that 10 of the 11 mutants also showed a weak cell surface expression, which was associated with a concomitant increase in the low molecular weight hypo-N-glycosylated immature gp130Fms-like species. Indeed, the mutant proteins heavily accumulated to the Golgi-like perinuclear regions. These results indicate that all of the Fms mutations tested severely impair the kinase activity and most of the mutations also impair the trafficking to the cell surface, further suggesting that HDLS is caused by the loss of Fms function.

  16. Temperature-dependent competition between adsorption and aggregation of a cellulose ether--simultaneous use of optical and acoustical techniques for investigating surface properties.

    Science.gov (United States)

    Bodvik, Rasmus; Macakova, Lubica; Karlson, Leif; Thormann, Esben; Claesson, Per

    2012-06-26

    Adsorption of the temperature-responsive polymer hydroxypropylmethylcellulose (HPMC) from an aqueous solution onto hydrophobized silica was followed well above the bulk instability temperature (T(2)) in temperature cycle experiments. Two complementary techniques, QCM-D and ellipsometry, were utilized simultaneously to probe the same substrate immersed in polymer solution. The interfacial processes were correlated with changes in polymer aggregation and viscosity of polymer solutions, as monitored by light scattering and rheological measurements. The simultaneous use of ellipsometry and QCM-D, and the possibility to follow layer properties up to 80 °C, well above the T(2) temperature, are both novel developments. A moderate increase in adsorbed amount with temperature was found below T(2), whereas a significant increase in the adsorbed mass and changes in layer properties were observed around the T(2) temperature where the bulk viscosity increases significantly. Thus, there is a clear correlation between transition temperatures in the adsorbed layer and in bulk solution, and we discuss this in relation to a newly proposed model that considers competition between aggregation and adsorption/deposition. A much larger temperature response above the T(2) temperature was found for adsorbed layers of HPMC than for layers of methyl cellulose. Possible reasons for this are discussed.

  17. HUMAN NK CELLS: FROM SURFACE RECEPTORS TO THE THERAPY OF LEUKEMIAS AND SOLID TUMORS

    Directory of Open Access Journals (Sweden)

    LORENZO eMORETTA

    2014-03-01

    Full Text Available Natural Killer (NK cells are major effector cells of the innate immunity. The discovery, over two decades ago, of MHC-class I specific NK receptors and subsequently of activating receptors, recognizing ligands expressed by tumor or virus-infected cells, paved the way to our understanding of the mechanisms of selective recognition and killing of tumor cells. Although NK cells can efficiently kill tumor cells of different histotypes in vitro, their activity may be limited in vivo by their inefficient trafficking to tumor lesions and by the inhibition of their function induced by tumor cells themselves and by the tumor microenvironment. On the other hand, the important role of NK cells has been clearly demonstrated in the therapy of high risk leukemias in the haploidentical hematopoietic cell (HSC transplantation setting. NK cells derived from donor HSC kill leukemic cells residual after the conditioning regimen, thus preventing leukemia relapses. In addition, they also kill residual dendritic cells and T lymphocytes, thus preventing both GvHD and graft rejection.

  18. Nanostructured hydroxyapatite surfaces-mediated adsorption alters recognition of BMP receptor IA and bioactivity of bone morphogenetic protein-2.

    Science.gov (United States)

    Huang, Baolin; Yuan, Yuan; Ding, Sai; Li, Jianbo; Ren, Jie; Feng, Bo; Li, Tong; Gu, Yuantong; Liu, Changsheng

    2015-11-01

    Highly efficient loading of bone morphogenetic protein-2 (BMP-2) onto carriers with desirable performance is still a major challenge in the field of bone regeneration. Till now, the nanoscaled surface-induced changes of the structure and bioactivity of BMP-2 remains poorly understood. Here, the effect of nanoscaled surface on the adsorption and bioactivity of BMP-2 was investigated with a series of hydroxyapatite surfaces (HAPs): HAP crystal-coated surface (HAP), HAP crystal-coated polished surface (HAP-Pol), and sintered HAP crystal-coated surface (HAP-Sin). The adsorption dynamics of recombinant human BMP-2 (rhBMP-2) and the accessibility of the binding epitopes of adsorbed rhBMP-2 for BMP receptors (BMPRs) were examined by a quartz crystal microbalance with dissipation. Moreover, the bioactivity of adsorbed rhBMP-2 and the BMP-induced Smad signaling were investigated with C2C12 model cells. A noticeably high mass-uptake of rhBMP-2 and enhanced recognition of BMPR-IA to adsorbed rhBMP-2 were found on the HAP-Pol surface. For the rhBMP-2-adsorbed HAPs, both ALP activity and Smad signaling increased in the order of HAP-Sinsurface with a relative loosened conformation, but the HAP-Sin surface induced a compact conformation of BMP-2. In conclusion, the nanostructured HAPs can modulate the way of adsorption of rhBMP-2, and thus the recognition of BMPR-IA and the bioactivity of rhBMP-2. These findings can provide insightful suggestions for the future design and fabrication of rhBMP-2-based scaffolds/implants. This study provides strong evidences that nanoscaled HAPs yield extraordinary influence on the adsorption behaviors and bioactivity of rhBMP-2. It has been found that the surface roughness and crystallinity played a crucial role in governing the way of rhBMP-2 binding to HAPs, and thus the conformation, recognition of

  19. Surface Toll-like receptor 3 expression in metastatic intestinal epithelial cells induces inflammatory cytokine production and promotes invasiveness.

    Science.gov (United States)

    Bugge, Marit; Bergstrom, Bjarte; Eide, Oda K; Solli, Helene; Kjønstad, Ingrid F; Stenvik, Jørgen; Espevik, Terje; Nilsen, Nadra J

    2017-09-15

    Toll-like receptors (TLRs) are innate immune receptors for sensing microbial molecules and damage-associated molecular patterns released from host cells. Double-stranded RNA and the synthetic analog polyinosinic:polycytidylic acid (poly(I:C)) bind and activate TLR3. This stimulation leads to recruitment of the adaptor molecule TRIF (Toll/IL-1 resistance (TIR) domain-containing adapter-inducing interferon β) and activation of the transcription factors nuclear factor κB (NF-κB) and interferon regulatory factor 3 (IRF-3), classically inducing IFNβ production. Here we report that, unlike non-metastatic intestinal epithelial cells (IECs), metastatic IECs express TLR3 and that TLR3 promotes invasiveness of these cells. In response to poly(I:C) addition, the metastatic IECs also induced the chemokine CXCL10 in a TLR3-, TRIF-, and IRF3-dependent manner but failed to produce IFNβ. This was in contrast to healthy and non-metastatic IECs, which did not respond to poly(I:C) stimulation. Endolysosomal acidification and the endosomal transporter protein UNC93B1 was required for poly(I:C)-induced CXCL10 production. However, TLR3-induced CXCL10 was triggered by immobilized poly(I:C), was only modestly affected by inhibition of endocytosis, and could be blocked with an anti-TLR3 antibody, indicating that TLR3 can still signal from the cell surface of these cells. Furthermore, plasma membrane fractions from metastatic IECs contained both full-length and cleaved TLR3, demonstrating surface expression of both forms of TLR3. Our results imply that metastatic IECs express surface TLR3, allowing it to sense extracellular stimuli that trigger chemokine responses and promote invasiveness in these cells. We conclude that altered TLR3 expression and localization may have implications for cancer progression. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Molecular Aspects of HTLV-1 Entry: Functional Domains of the HTLV-1 Surface Subunit (SU and Their Relationships to the Entry Receptors

    Directory of Open Access Journals (Sweden)

    Sophie Lambert

    2011-06-01

    Full Text Available The initial step in retroviral infection involves specific interactions between viral envelope proteins (Env and specific receptors on the surface of target cells. For many years, little was known about the entry receptors for HTLV-1. During this time, however, functional domains of the HTLV-1 Env were identified by analyzing the effects of neutralizing antibodies and specific mutations in Env on HTLV-1 infectivity. More recent studies have revealed that HTLV-1 infectivity involves interactions with three different molecules: heparan sulfate proteoglycans (HSPG, the VEGF-165 receptor Neuropilin 1 (NRP-1 and glucose transporter type 1 (GLUT1. Here, we revisit previously published data on the functional domains of Env in regard to the recent knowledge acquired about this multi-receptor complex. We also discuss the similarities and differences between HTLV-1 and other deltaretroviruses in regards to receptor usage.

  1. Distinguishing aggregate formation and aggregate clearance using cell based assays

    NARCIS (Netherlands)

    E. Eenjes, E.; J.M. Dragich; H. Kampinga (Harm); A. Yamamoto, A.

    2016-01-01

    textabstractThe accumulation of ubiquitinated proteinaceous inclusions represents a complex process, reflecting the disequilibrium between aggregate formation and aggregate clearance. Although decreasing aggregate formation or augmenting aggregate clearance will ultimately lead to diminished

  2. Interplay between Dopamine and γ2- AminoButyric Acid type A receptors' surface dynamics during maturation of neurons and development of hippocampal networks.

    OpenAIRE

    Matias, Miguel Albino

    2015-01-01

    MATIAS, Miguel Albino - Interplay between Dopamine and γ2- AminoButyric Acid type A receptors' surface dynamics during maturation of neurons and development of hippocampal networks. Coimbra : [s.n.], 2015. Dissertação de Mestrado em Biologia Celular e Molecular. A dynamic synapse is crucial not only in the regulation of synaptic transmission but also for maturation and development of neurons and neuronal circuits. This is particularly important in the case of receptors, whic...

  3. Phenomenology of optical scattering from plasmonic aggregates for application to biological imaging and clinical therapeutics

    Science.gov (United States)

    Travis, Kort; Aaron, Jesse; Harrison, Nathan; Sokolov, Konstantin

    2008-02-01

    Near-field coupling between plasmonic resonant nanoparticles and the associated shifts in scattering spectra enables the accomplishment of unprecedented observation of the co-localization dynamics of in-situ biomolecules on nanometer length-scales. We have recently shown that resonant nanoparticles conjugated to antibodies for cell-surface receptors provide a sensitive probe allowing the unambiguous resolution of not only the time sequence, but also the details of the intracellular pathway, for receptor-mediated endocytosis in live cells. In terms of general principles, the classical electrodynamics determining the scattering cross-section for nanoparticle aggregates is straightforward. However, the specifics of the angular dependence of the differential cross-section at a single wavelength, the wavelength dependence of this cross-section, and the correct implementation and interpretation of statistical averages of cross-section properties over an ensemble of aggregate morphologies are generally quite complicated, and in fact are often misinterpreted in the literature. Despite this complexity, we have constructed a set of few-parameter formulae describing optical scattering from nanoparticle aggregates by judicious combination of experimental results with extensive, near-exact simulation using the T-matrix technique. These phenomenological results facilitate the practical use of nanoparticle aggregates for biological measurement and clinical therapeutic applications.

  4. Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates of Bacteria on Mars Landers

    Science.gov (United States)

    Schuerger, Andrew C.; Kern, Roger G.

    2004-01-01

    In order to minimize the forward contamination of Mars, spacecraft are assembled under cleanroom conditions that require several procedures to clean and sterilize components. Surface characteristics of spacecraft materials may contribute to microbial survival on the surface of Mars by protecting spores from sterilizing agents, including UV irradiation. The primary objective of this study was to evaluate the effects of surface characteristics of several spacecraft materials on the survival of Bacillus subtilis spores under simulated Martian conditions.

  5. Vaccination targeting surface FomA of Fusobacterium nucleatum against bacterial co-aggregation: implication for treatment of periodontal infection and halitosis

    Science.gov (United States)

    Liu, Pei-Feng; Shi, Wenyuan; Zhu, Wenhong; Smith, Jeffery W.; Hsieh, Shie-Liang; Gallo, Richard L.; Huang, Chun-Ming

    2010-01-01

    The mechanical therapy with multiple doses of antibiotics is one of modalities for treatment of periodontal diseases. However, treatments using multiple doses of antibiotics carry risks of generating resistant strains and misbalancing the resident body flora. We present an approach via immunization targeting an outer membrane protein FomA of Fusobacterium nucleatum, a central bridging organism in the architecture of oral biofilms. Neutralization of FomA considerably abrogated the enhancement of bacterial co-aggregation, biofilms and production of volatile sulfur compounds mediated by an interspecies interaction of F. nucleatum with Porphyromonas gingivalis (P. gingivalis). Vaccination targeting FomA also conferred a protective effect against co-infection-induced gum inflammation. Here, we advance a novel infectious mechanism by which F. nucleatum co-opts P. gingivalis to exacerbate gum infections. FomA is highlighted as a potential target for development of new therapeutics against periodontal infection and halitosis in humans. PMID:20189489

  6. Surface characteristics of spacecraft components affect the aggregation of microorganisms and may lead to different survival rates of bacteria on Mars landers

    Science.gov (United States)

    Schuerger, Andrew C.; Richards, Jeffrey T.; Hintze, Paul E.; Kern, Roger G.

    2005-01-01

    Layers of dormant endospores of Bacillus subtilis HA101 were applied to eight different spacecraft materials and exposed to martian conditions of low pressure (8.5 mbar), low temperature (-10 degrees C), and high CO(2) gas composition and irradiated with a Mars-normal ultraviolet (UV-visible- near-infrared spectrum. Bacterial layers were exposed to either 1 min or 1 h of Mars-normal UV irradiation, which simulated clear-sky conditions on equatorial Mars (0.1 tau). When exposed to 1 min of Mars UV irradiation, the numbers of viable endospores of B. subtilis were reduced three to four orders of magnitude for two brands of aluminum (Al), stainless steel, chemfilm-treated Al, clear-anodized Al, and black-anodized Al coupons. In contrast, bacterial survival was reduced only one to two orders of magnitude for endospores on the non-metal materials astroquartz and graphite composite when bacterial endospores were exposed to 1 min of Mars UV irradiation. When bacterial monolayers were exposed to 1 h of Mars UV irradiation, no viable bacteria were recovered from the six metal coupons listed above. In contrast, bacterial survival was reduced only two to three orders of magnitude for spore layers on astroquartz and graphite composite exposed to 1 h of Mars UV irradiation. Scanning electron microscopy images of the bacterial monolayers on all eight spacecraft materials revealed that endospores of B. subtilis formed large aggregates of multilayered spores on astroquartz and graphite composite, but not on the other six spacecraft materials. It is likely that the formation of multilayered aggregates of endospores on astroquartz and graphite composite is responsible for the enhanced survival of bacterial cells on these materials.

  7. An epirubicin-peptide conjugate with anticancer activity is dependent upon the expression level of the surface transferrin receptor.

    Science.gov (United States)

    Yang, Jiadan; Yang, Qiyu; Xu, Lu; Lou, Jie; Dong, Zhi

    2017-01-01

    Epirubicin (EPI) is one of the most widely used anticarcinogens; however, serious side effects, including cardiomyopathy and congestive heart failure, limit its long‑term administration. To overcome this problem, the HAIYPRH peptide ligand was used with EPI in the synthesis of a HAIYPRH‑EPI conjugate. The anticancer activity and cellular uptake of the conjugate were measured and evaluated. The results of the present study indicated that the cytotoxicity of HAIYPRH‑EPI was correlated with the expression of the cell surface transferrin receptor (TfR). The conjugate exerted high cytotoxicity and proapoptotic function when in an LN229 glioma cell line, which overexpresses surface TfR. It was hypothesized that transferrin (Tf) can promote cytotoxicity. Conversely, the conjugate exhibited very low cytotoxicity and proapoptotic function in a U87 glioma cell line, in which surface TfR expression was undetectable. In addition, fluorescence microscopy and flow cytometry methods were used to evaluate cellular uptake, and the results of these methods were consistent with the present hypotheses. The conjugate cellular uptake of the conjugate in LN229 cells was markedly higher compared with that in U87 cells, and it was hypothesized that Tf can enhance the uptake in LN229 cells. The cytotoxicity of HAIYPRH‑EPI was dependent upon the expression of surface TfR. Considering that the majority of cancer cells have high rates of iron uptake and surface TfR is generally overexpressed on cancer cells, it was speculated by the authors that HAIYPRH‑EPI may form part of an effective strategy for increasing the selectivity of EPI for cancer cells, as well as reducing its systemic toxicity. To confirm the hypothesis, the effects of HAIYPRH‑EPI on non‑cancerous cell lines were investigated. A future study will examine the side effects of HAIYPRH‑EPI, using a suitable delivery system in an animal model.

  8. Impact of Cell-surface Antigen Expression on Target Engagement and Function of an Epidermal Growth Factor Receptor × c-MET Bispecific Antibody.

    Science.gov (United States)

    Jarantow, Stephen W; Bushey, Barbara S; Pardinas, Jose R; Boakye, Ken; Lacy, Eilyn R; Sanders, Renouard; Sepulveda, Manuel A; Moores, Sheri L; Chiu, Mark L

    2015-10-09

    The efficacy of engaging multiple drug targets using bispecific antibodies (BsAbs) is affected by the relative cell-surface protein levels of the respective targets. In this work, the receptor density values were correlated to the in vitro activity of a BsAb (JNJ-61186372) targeting epidermal growth factor receptor (EGFR) and hepatocyte growth factor receptor (c-MET). Simultaneous binding of the BsAb to both receptors was confirmed in vitro. By using controlled Fab-arm exchange, a set of BsAbs targeting EGFR and c-MET was generated to establish an accurate receptor quantitation of a panel of lung and gastric cancer cell lines expressing heterogeneous levels of EGFR and c-MET. EGFR and c-MET receptor density levels were correlated to the respective gene expression levels as well as to the respective receptor phosphorylation inhibition values. We observed a bias in BsAb binding toward the more highly expressed of the two receptors, EGFR or c-MET, which resulted in the enhanced in vitro potency of JNJ-61186372 against the less highly expressed target. On the basis of these observations, we propose an avidity model of how JNJ-61186372 engages EGFR and c-MET with potentially broad implications for bispecific drug efficacy and design. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Renewal of the air-water interface as a critical system parameter of protein stability: aggregation of the human growth hormone and its prevention by surface-active compounds.

    Science.gov (United States)

    Wiesbauer, Johanna; Prassl, Ruth; Nidetzky, Bernd

    2013-12-10

    Soluble proteins are often highly unstable under mixing conditions that involve dynamic contacting between the main liquid phase and a gas phase. The recombinant human growth hormone (rhGH) was recently shown to undergo aggregation into micrometer-sized solid particles composed of non-native (mis- or unfolded) protein, once its solutions were stirred or shaken to generate a continuously renewed air-water interface. To gain deepened understanding and improved quantification of the air-water interface effect on rhGH stability, we analyzed the protein's aggregation rate (r(agg)) at controlled specific air-water surface areas (a(G/L)) established by stirring or bubble aeration. We show that in spite of comparable time-averaged values for a(G/L) (≈ 100 m(2)/m(3)), aeration gave a 40-fold higher r(agg) than stirring. The enhanced r(agg) under aeration was ascribed to faster macroscopic regeneration of free a(G/L) during aeration as compared to stirring. We also show that r(agg) was independent of the rhGH concentration in the range 0.67 - 6.7 mg/mL, and that it increased linearly dependent on the available a(G/L). The nonionic surfactant Pluronic F-68, added in 1.6-fold molar excess over rhGH present, resulted in complete suppression of r(agg). Foam formation was not a factor influencing r(agg). Using analysis by circular dichroism spectroscopy and small-angle X-ray scattering, we show that in the presence of Pluronic F-68 under both stirring and aeration, the soluble protein retained its original fold, featuring native-like relative composition of secondary structural elements. We further provide evidence that the efficacy of Pluronic F-68 resulted from direct, probably hydrophobic protein-surfactant interactions that prevented rhGH from becoming attached to the air-water interface. Surface-induced aggregation of rhGH is suggested to involve desorption of non-native protein from the air-water interface as the key limiting step. Proteins or protein aggregates released

  10. 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. A...

  11. Determination and Modulation of Total and Surface Calcium-Sensing Receptor Expression in Monocytes In Vivo and In Vitro

    Science.gov (United States)

    Paccou, Julien; Boudot, Cédric; Mary, Aurélien; Kamel, Said; Drüeke, Tilman Bernhard; Fardellone, Patrice; Massy, Ziad; Brazier, Michel; Mentaverri, Romuald

    2013-01-01

    Expression of the calcium-sensing receptor (CaSR) has previously been demonstrated in human circulating monocytes (HCM). The present study was designed to measure CaSR expression in HCM and to examine its potential modulation by pro-inflammatory cytokines, Ca2+, vitamin D sterols in U937 cell line. Twenty healthy volunteers underwent blood sampling with subsequent isolation of peripheral blood mononuclear cells (PBMC) at 3 visits. Flow cytometry analysis (FACS) was performed initially (V1) and 19 days later (V2) to examine intra- and intersubject fluctuations of total and surface CaSR expression in HCM and 15 weeks later (V3) to study the effect of vitamin D supplementation. In vitro experiments were conducted to assess the effects of pro-inflammatory cytokines, calcidiol, calcitriol and Ca2+ on CaSR expression in U937 cell line. By FACS analysis, more than 95% of HCM exhibited cell surface CaSR staining. In contrast, CaSR staining failed to detect surface CaSR expression in other PBMC. After cell permeabilization, total CaSR expression was observed in more than 95% of all types of PBMC. Both total and surface CaSR expression in HCM showed a high degree of intra-assay reproducibility (<3%) and a moderate intersubject fluctuation. In response to vitamin D supplementation, there was no significant change for both total and surface CaSR expression. In the in vitro study, U937 cells showed strong total and surface CaSR expression, and both were moderately increased in response to calcitriol exposure. Neither total nor surface CaSR expression was modified by increasing Ca2+ concentrations. Total CaSR expression was concentration dependently decreased by TNFα exposure. In conclusion, CaSR expression can be easily measured by flow cytometry in human circulating monocytes. In the in vitro study, total and surface CaSR expression in the U937 cell line were increased by calcitriol but total CaSR expression was decreased by TNFα stimulation. PMID:24098349

  12. Cell wall trapping of autocrine peptides for human G-protein-coupled receptors on the yeast cell surface.

    Directory of Open Access Journals (Sweden)

    Jun Ishii

    Full Text Available G-protein-coupled receptors (GPCRs regulate a wide variety of physiological processes and are important pharmaceutical targets for drug discovery. Here, we describe a unique concept based on yeast cell-surface display technology to selectively track eligible peptides with agonistic activity for human GPCRs (Cell Wall Trapping of Autocrine Peptides (CWTrAP strategy. In our strategy, individual recombinant yeast cells are able to report autocrine-positive activity for human GPCRs by expressing a candidate peptide fused to an anchoring motif. Following expression and activation, yeast cells trap autocrine peptides onto their cell walls. Because captured peptides are incapable of diffusion, they have no impact on surrounding yeast cells that express the target human GPCR and non-signaling peptides. Therefore, individual yeast cells can assemble the autonomous signaling complex and allow single-cell screening of a yeast population. Our strategy may be applied to identify eligible peptides with agonistic activity for target human GPCRs.

  13. Orthogonal flexible Rydberg aggregates

    Science.gov (United States)

    Leonhardt, K.; Wüster, S.; Rost, J. M.

    2016-02-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali-metal atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable nonadiabatic effects. A joint exciton-motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of nonadiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K. Leonhardt et al., Phys. Rev. Lett. 113, 223001 (2014), 10.1103/PhysRevLett.113.223001]. In this article we discuss the underlying complex dynamics in detail, characterize the switch, and derive our isotropic interaction model from a realistic anisotropic one with the addition of a magnetic bias field.

  14. Factor VIII interacts with the endocytic receptor low-density lipoprotein receptor-related protein 1 via an extended surface comprising "hot-spot" lysine residues

    NARCIS (Netherlands)

    Van Den Biggelaar, Maartje|info:eu-repo/dai/nl/304831433; Madsen, Jesper J.; Faber, Johan H.; Zuurveld, Marleen G.; Van Der Zwaan, Carmen; Olsen, Ole H.; Stennicke, Henning R.; Mertens, Koen|info:eu-repo/dai/nl/070940258; Meijer, Alexander B.

    2015-01-01

    Background: It is unclear how the LDL receptor family binds large protein ligands. Results: HDX and lysine scanning identified factor (F)VIII regions and specific lysine residues binding low-density lipoprotein receptor-related protein 1 (LRP1). Conclusion: FVIII-LRP1 interaction involves multiple

  15. Aryl hydrocarbon receptor (AhR) inducers and estrogen receptor (ER) activities in surface sediments of Three Gorges Reservoir, China evaluated with in vitro cell bioassays

    NARCIS (Netherlands)

    Wang, J.; Bovee, T.F.H.; Bi, Y.; Bernhöft, S.; Schramm, K.W.

    2014-01-01

    Two types of biological tests were employed for monitoring the toxicological profile of sediment cores in the Three Gorges Reservoir (TGR), China. In the present study, sediments collected in June 2010 from TGR were analyzed for estrogen receptor (ER)- and aryl hydrocarbon receptor (AhR)-mediated

  16. Attenuation of chemokine receptor function and surface expression as an immunomodulatory strategy employed by human cytomegalovirus is linked to vGPCR US28

    DEFF Research Database (Denmark)

    Frank, Theresa; Reichel, Anna; Larsen, Olav

    2016-01-01

    Background Some herpesviruses like human cytomegalovirus (HCMV) encode viral G protein-coupled receptors that cause reprogramming of cell signaling to facilitate dissemination of the virus, prevent immune surveillance and establish life-long latency. Human GPCRs are known to function in complex......-delUS28 infected cells, CXCR4 surface expression is not altered in particular at late time points of infection. Conclusions We show that the vGPCR US28 is leading to severely disturbed signaling and surface expression of the chemokine receptor CXCR4 thereby representing an effective mechanism used by vGPCRs...

  17. The urokinase receptor takes control of cell migration by recruiting integrins and FPR1 on the cell surface.

    Directory of Open Access Journals (Sweden)

    Anna Gorrasi

    Full Text Available The receptor (uPAR of the urokinase-type plasminogen activator (uPA is crucial in cell migration since it concentrates uPA proteolytic activity at the cell surface, binds vitronectin and associates to integrins. uPAR cross-talk with receptors for the formylated peptide fMLF (fMLF-Rs has been reported; however, cell-surface uPAR association to fMLF-Rs on the cell membrane has never been explored in detail. We now show that uPAR co-localizes at the cell-surface and co-immunoprecipitates with the high-affinity fMLF-R, FPR1, in uPAR-transfected HEK-293 (uPAR-293 cells. uPAR/β1 integrin and FPR1/β1 integrin co-localization was also observed. Serum or the WKYMVm peptide (W Pep, a FPR1 ligand, strongly increased all observed co-localizations in uPAR-293 cells, including FPR1/β1 integrin co-localization. By contrast, a low FPR1/β1 integrin co-localization was observed in uPAR-negative vector-transfected HEK-293 (V-293 cells, that was not increased by serum or W Pep stimulations. The role of uPAR interactions in cell migration was then explored. Both uPAR-293 and V-293 control cells efficiently migrated toward serum or purified EGF. However, cell treatments impairing uPAR interactions with fMLF-Rs or integrins, or inhibiting specific cell-signaling mediators abrogated uPAR-293 cell migration, without exerting any effect on V-293 control cells. Accordingly, uPAR depletion by a uPAR-targeting siRNA or uPAR blocking with an anti-uPAR polyclonal antibody in cells constitutively expressing high uPAR levels totally impaired their migration toward serum. Altogether, these results suggest that both uPAR-positive and uPAR-negative cells are able to migrate toward serum; however, uPAR expression renders cell migration totally and irreversibly uPAR-dependent, since it is completely inhibited by uPAR blocking. We propose that uPAR takes control of cell migration by recruiting fMLF-Rs and β1 integrins, thus promoting their co-localization at the cell-surface and

  18. Membrane Ballooning in Aggregated Platelets is Synchronised and Mediates a Surge in Microvesiculation.

    Science.gov (United States)

    Agbani, Ejaife O; Williams, Christopher M; Hers, Ingeborg; Poole, Alastair W

    2017-06-05

    Human platelet transformation into balloons is part of the haemostatic response and thrombus architecture. Here we reveal that in aggregates of platelets in plasma, ballooning in multiple platelets occurs in a synchronised manner. This suggests a mechanism of coordination between cells, previously unrecognised. We aimed to understand this mechanism, and how it may contribute to thrombus development. Using spinning-disc confocal microscopy we visualised membrane ballooning in human platelet aggregates adherent to collagen-coated surfaces. Within an aggregate, multiple platelets undergo ballooning in a synchronised fashion, dependent upon extracellular calcium, in a manner that followed peak cytosolic calcium levels in the aggregate. Synchrony was observed in platelets within but not between aggregates, suggesting a level of intra-thrombus communication. Blocking phosphatidylserine, inhibiting thrombin or blocking PAR1 receptor, largely prevented synchrony without blocking ballooning itself. In contrast, inhibition of connexins, P2Y12, P2Y1 or thromboxane formation had no effect on synchrony or ballooning. Importantly, synchronised ballooning was closely followed by a surge in microvesicle formation, which was absent when synchrony was blocked. Our data demonstrate that the mechanism underlying synchronised membrane ballooning requires thrombin generation acting effectively in a positive feedback loop, mediating a subsequent surge in procoagulant activity and microvesicle release.

  19. Area-averaged evapotranspiration over a heterogeneous land surface: aggregation of multi-point EC flux measurements with a high-resolution land-cover map and footprint analysis

    Science.gov (United States)

    Xu, Feinan; Wang, Weizhen; Wang, Jiemin; Xu, Ziwei; Qi, Yuan; Wu, Yueru

    2017-08-01

    The determination of area-averaged evapotranspiration (ET) at the satellite pixel scale/model grid scale over a heterogeneous land surface plays a significant role in developing and improving the parameterization schemes of the remote sensing based ET estimation models and general hydro-meteorological models. The Heihe Watershed Allied Telemetry Experimental Research (HiWATER) flux matrix provided a unique opportunity to build an aggregation scheme for area-averaged fluxes. On the basis of the HiWATER flux matrix dataset and high-resolution land-cover map, this study focused on estimating the area-averaged ET over a heterogeneous landscape with footprint analysis and multivariate regression. The procedure is as follows. Firstly, quality control and uncertainty estimation for the data of the flux matrix, including 17 eddy-covariance (EC) sites and four groups of large-aperture scintillometers (LASs), were carefully done. Secondly, the representativeness of each EC site was quantitatively evaluated; footprint analysis was also performed for each LAS path. Thirdly, based on the high-resolution land-cover map derived from aircraft remote sensing, a flux aggregation method was established combining footprint analysis and multiple-linear regression. Then, the area-averaged sensible heat fluxes obtained from the EC flux matrix were validated by the LAS measurements. Finally, the area-averaged ET of the kernel experimental area of HiWATER was estimated. Compared with the formerly used and rather simple approaches, such as the arithmetic average and area-weighted methods, the present scheme is not only with a much better database, but also has a solid grounding in physics and mathematics in the integration of area-averaged fluxes over a heterogeneous surface. Results from this study, both instantaneous and daily ET at the satellite pixel scale, can be used for the validation of relevant remote sensing models and land surface process models. Furthermore, this work will be

  20. Changes in surface expression of N-methyl-D-aspartate receptors in the striatum in a rat model of Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Gan J

    2014-01-01

    Full Text Available Jing Gan,1 Chen Qi,1 Li-Min Mao,2 Zhenguo Liu11Department of Neurology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China; 2Department of Basic Medical Science, University of Missouri-Kansas City School of Medicine, Kansas City, MO, USABackground: N-methyl-D-aspartate (NMDA receptors play a central role in glutamatergic synaptic transmission in the mammalian brain and are linked to the pathophysiology and symptomatology of Parkinson's disease (PD. However, changes in NMDA receptor expression in distinct subcellular compartments in PD have not been elucidated. In this study, we investigated changes in subcellular expression of NMDA receptors in striatal neurons in a rodent PD model.Methods: Intracranial injection of the neurotoxin 6-hydroxydopamine (6-OHDA was selectively lesioned into the nigrostriatal dopaminergic pathway in adult Sprague Dawley rats, which is a common rat model of PD. A surface receptor crosslinking assay was conducted to examine the response of individual NMDA receptor subunits to dopamine depletion in isolated and confined surface and intracellular compartments of striatal neurons.Results: In PD rats where 6-OHDA was selectively lesioned, surface expression of NMDA receptor GluN1 subunits as detected by surface protein crosslinking assays was increased in the striatum. In contrast, intracellular levels of GluN1 were decreased in the lesioned region. The NMDA receptor GluN2B subunit was elevated in its abundance in the surface pool of the lesioned striatum, while intracellular GluN2B levels were not altered. GluN2A subunits in both surface and intracellular fractions remained stable. In addition, total cellular levels of striatal GluN1 and GluN2A were not changed in lesioned tissue, while total GluN2B proteins showed an increase.Conclusion: These results demonstrate the differential sensitivity of principal NMDA receptor subunits to dopamine depletion. GluN1 and GluN2B

  1. Polysiloxane surface modified with bipyrazolic tripodal receptor for quantitative lead adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Radi, Smaail, E-mail: radi_smaail@yahoo.fr [Laboratoire de Chimie Organique, Macromoleculaire et Produits Naturels, Equipe de Chimie Bio-organique et Macromoleculaire, Unite Associee au CNRST URAC 25, Departement de Chimie, Faculte des Sciences, Universite Med I, BP 524, 60 000 Oujda (Morocco); Tighadouini, Said; Toubi, Yahya [Laboratoire de Chimie Organique, Macromoleculaire et Produits Naturels, Equipe de Chimie Bio-organique et Macromoleculaire, Unite Associee au CNRST URAC 25, Departement de Chimie, Faculte des Sciences, Universite Med I, BP 524, 60 000 Oujda (Morocco); Bacquet, Maryse [Universite des Sciences et Technologies de Lille, UMET: Unite Materiaux et Transformations UMR8207, Equipe Ingenierie des Systemes Polymeres, Batiment C6 salle 119-59655 Villeneuve d' Ascq (France)

    2011-01-15

    A new silica gel compound modified N,N-bis(3,5-dimethylpyrazol-1-ylmethyl) amine (SiN{sub 2}Pz) was synthesized and characterized by elemental analysis, FT-IR, {sup 13}C NMR of the solid state, nitrogen adsorption-desorption isotherm, BET surface area and BJH pore sizes. The new surface exhibits good chemical and thermal stability determined by thermogravimetry curves (TGA). The effect of pH and stirring time on the adsorption of Pb(II) were studied. The process of metal retention was followed by batch method and the optimum pH value for the quantitative adsorption of this toxic metal ion was 7. At this pH value, the new functionalized polysiloxane presents further improvements and shows higher affinity (123 mg of Pb{sup 2+}/g of silica) for the effective adsorption of Pb(II) compared to others described sorbents. The extracted amounts of Pb(II) were determined by atomic absorption measurements.

  2. A cleavable signal peptide enhances cell surface delivery and heterodimerization of Cerulean-tagged angiotensin II AT1 and bradykinin B2 receptor

    Energy Technology Data Exchange (ETDEWEB)

    Quitterer, Ursula, E-mail: ursula.quitterer@pharma.ethz.ch [Molecular Pharmacology Unit, Swiss Federal Institute of Technology and University of Zurich, Zurich (Switzerland); Pohl, Armin; Langer, Andreas; Koller, Samuel; AbdAlla, Said [Molecular Pharmacology Unit, Swiss Federal Institute of Technology and University of Zurich, Zurich (Switzerland)

    2011-06-10

    Highlights: {yields} A new FRET-based method detects AT1/B2 receptor heterodimerization. {yields} First time application of AT1-Cerulean as a FRET donor. {yields} Method relies on signal peptide-enhanced cell surface delivery of AT1-Cerulean. {yields} A high FRET efficiency revealed efficient heterodimerization of AT1/B2R proteins. {yields} AT1/B2R heterodimers were functionally coupled to desensitization mechanisms. -- Abstract: Heterodimerization of the angiotensin II AT1 receptor with the receptor for the vasodepressor bradykinin, B2R, is known to sensitize the AT1-stimulated response of hypertensive individuals in vivo. To analyze features of that prototypic receptor heterodimer in vitro, we established a new method that uses fluorescence resonance energy transfer (FRET) and applies for the first time AT1-Cerulean as a FRET donor. The Cerulean variant of the green fluorescent protein as donor fluorophore was fused to the C-terminus of AT1, and the enhanced yellow fluorescent protein (EYFP) as acceptor fluorophore was fused to B2R. In contrast to AT1-EGFP, the AT1-Cerulean fusion protein was retained intracellularly. To facilitate cell surface delivery of AT1-Cerulean, a cleavable signal sequence was fused to the receptor's amino terminus. The plasma membrane-localized AT1-Cerulean resembled the native AT1 receptor regarding ligand binding and receptor activation. A high FRET efficiency of 24.7% between membrane-localized AT1-Cerulean and B2R-EYFP was observed with intact, non-stimulated cells. Confocal FRET microscopy further revealed that the AT1/B2 receptor heterodimer was functionally coupled to receptor desensitization mechanisms because activation of the AT1-Cerulean/B2R-EYFP heterodimer with a single agonist triggered the co-internalization of AT1/B2R. Receptor co-internalization was sensitive to inhibition of G protein-coupled receptor kinases, GRKs, as evidenced by a GRK-specific peptide inhibitor. In agreement with efficient AT1/B2R

  3. Two step formation of metal aggregates by surface X-ray radiolysis under Langmuir monolayers: 2D followed by 3D growth

    Directory of Open Access Journals (Sweden)

    Smita Mukherjee

    2015-12-01

    Full Text Available In order to form a nanostructured metallic layer below a Langmuir monolayer, radiolysis synthesis was carried out in an adapted geometry that we call surface X-ray radiolysis. In this procedure, an X-ray beam produced by a synchrotron beamline intercepts the surface of an aqueous metal-ion solution covered by a Langmuir monolayer at an angle of incidence below the critical angle for total internal reflection. Underneath the organic layer, the X-ray beam induces the radiolytic synthesis of a nanostructured metal–organic layer whose ultrathin thickness is defined by the vertical X-ray penetration depth. We have shown that increasing the X-ray flux on the surface, which considerably enhances the kinetics of the silver layer formation, results in a second growth regime of silver nanocrystals. Here the formation of the oriented thin layer is followed by the appearance of a 3D powder of silver clusters.

  4. Marginal adaptation of mineral trioxide aggregate (MTA) to root dentin surface with orthograde/retrograde application techniques: A microcomputed tomographic analysis.

    Science.gov (United States)

    Al Fouzan, Khalid; Awadh, Mohammed; Badwelan, Moahmmed; Gamal, Abeer; Geevarghese, Amrita; Babhair, Samar; Al-Rejaie, Mansour; Al Hezaimi, Khalid; Rotstein, Ilan

    2015-01-01

    Achieving a good apical seal for root canals is known to be associated with good mineral trioxide aggregate (MTA) adaptation to dentin. This study aims to compare the marginal adaptation of MTA with root dentin between orthograde and retrograde application techniques using microcomputed tomography (micro-CT) analysis. Fifty-two single-rooted human teeth were divided into four equal groups: (Group 1) Retrograde MTA (RMTA), (Group 2) Orthograde MTA (OMTA), (Group 3) Etched RMTA (ERMTA), and (Group 4) Etched OMTA (EOMTA). For Group 1, 3-mm retrograde cavities were prepared and filled with MTA. For Group 2, the apical 6 mm of the canals were filled with MTA and sealed with sealer cement and warm gutta-percha. In Groups 3 and 4, canals were treated the same as Groups 1 and 2, respectively, except that before placing the MTA, canals were irrigated with 17% ethylenediaminetetraacetic acid (EDTA). After 48 hours, all the teeth were analyzed using a micro-CT scanner. Mean dentin-MTA contact and the mean length and width of each gap was analysed using one-way analysis of variance (ANOVA). Statistical significance was set at an α level of 5%. No significant difference in gap volumes was observed in the dentin-MTA adaptation in both orthograde and retrograde application techniques. However, significant difference in the gap volumes was observed between RMTA and ERMTA (P = 0.045). Etching significantly improved the MTA-Dentin adaptation (P MTA adaptation, instead with the use of 17% EDTA, a significant improvement could be achieved. Within the limitations of the present study, it concludes that MTA adaptation to dentin tooth structure is not significantly different between an orthograde and retrograde approach. However, the use of EDTA significantly improved the MTA-Dentin adaptation.

  5. Genetic Variations in the Human G Protein-coupled Receptor Class C, Group 6, Member A (GPRC6A) Control Cell Surface Expression and Function

    DEFF Research Database (Denmark)

    Jorgensen, Stine; Have, Christian Theil; Underwood, Christina Rye

    2017-01-01

    GPRC6A is a G protein-coupled receptor activated by l-amino acids, which, based on analyses of knock-out mice, has been suggested to have physiological functions in metabolism and testicular function. The human ortholog is, however, mostly retained intracellularly in contrast to the cell surface-...

  6. A Genotypic Analysis of Five P. aeruginosa Strains after Biofilm Infection by Phages Targeting Different Cell Surface Receptors

    Directory of Open Access Journals (Sweden)

    Diana P. Pires

    2017-06-01

    Full Text Available Antibiotic resistance constitutes one of the most serious threats to the global public health and urgently requires new and effective solutions. Bacteriophages are bacterial viruses increasingly recognized as being good alternatives to traditional antibiotic therapies. In this study, the efficacy of phages, targeting different cell receptors, against Pseudomonas aeruginosa PAO1 biofilm and planktonic cell cultures was evaluated over the course of 48 h. Although significant reductions in the number of viable cells were achieved for both cases, the high level of adaptability of the bacteria in response to the selective pressure caused by phage treatment resulted in the emergence of phage-resistant variants. To further investigate the genetic makeup of phage-resistant variants isolated from biofilm infection experiments, some of these bacteria were selected for phenotypic and genotypic characterization. Whole genome sequencing was performed on five phage-resistant variants and all of them carried mutations affecting the galU gene as well as one of pil genes. The sequencing analysis further revealed that three of the P. aeruginosa PAO1 variants carry large deletions (>200 kbp in their genomes. Complementation of the galU mutants with wild-type galU in trans restored LPS expression on the bacterial cell surface of these bacterial strains and rendered the complemented strains to be sensitive to phages. This provides unequivocal evidence that inactivation of galU function was associated with resistance to the phages that uses LPS as primary receptors. Overall, this work demonstrates that P. aeruginosa biofilms can survive phage attack and develop phage-resistant variants exhibiting defective LPS production and loss of type IV pili that are well adapted to the biofilm mode of growth.

  7. Corrosion performance of reinforced mortar in the presence of polymeric nano-aggregates : Electrochemical behavior, surface analysis, and properties of the steel/cement paste interface

    NARCIS (Netherlands)

    Hu, J.; Koleva, D.A.; Van Breugel, K.

    2012-01-01

    This study reports on the effect of admixed polyethylene oxide-b-polystyrene (PEO113-b-PS70)micelles on corrosion behavior of reinforced mortar. The electrochemical measurement shows that the corrosion performance of the reinforcing steel was not significantly improved. However, surface analysis and

  8. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...

  9. Enhanced Growth Inhibition of Osteosarcoma by Cytotoxic Polymerized Liposomal Nanoparticles Targeting the Alcam Cell Surface Receptor

    Directory of Open Access Journals (Sweden)

    Noah Federman

    2012-01-01

    Full Text Available Osteosarcoma is the most common primary malignancy of bone in children, adolescents, and adults. Despite extensive surgery and adjuvant aggressive high-dose systemic chemotherapy with potentially severe bystander side effects, cure is attainable in about 70% of patients with localized disease and only 20%–30% of those patients with metastatic disease. Targeted therapies clearly are warranted in improving our treatment of this adolescent killer. However, a lack of osteosarcoma-associated/specific markers has hindered development of targeted therapeutics. We describe a novel osteosarcoma-associated cell surface antigen, ALCAM. We, then, create an engineered anti-ALCAM-hybrid polymerized liposomal nanoparticle immunoconjugate (α-AL-HPLN to specifically target osteosarcoma cells and deliver a cytotoxic chemotherapeutic agent, doxorubicin. We have demonstrated that α-AL-HPLNs have significantly enhanced cytotoxicity over untargeted HPLNs and over a conventional liposomal doxorubicin formulation. In this way, α-AL-HPLNs are a promising new strategy to specifically deliver cytotoxic agents in osteosarcoma.

  10. Aggregates from mineral wastes

    Directory of Open Access Journals (Sweden)

    Baic Ireneusz

    2016-01-01

    Full Text Available The problem concerning the growing demand for natural aggregates and the need to limit costs, including transportation from remote deposits, cause the increase in growth of interest in aggregates from mineral wastes as well as in technologies of their production and recovery. The paper presents the issue related to the group of aggregates other than natural. A common name is proposed for such material: “alternative aggregates”. The name seems to be fully justified due to adequacy of this term because of this raw materials origin and role, in comparison to the meaning of natural aggregates based on gravel and sand as well as crushed stones. The paper presents characteristics of the market and basic application of aggregates produced from mineral wastes, generated in the mining, power and metallurgical industries as well as material from demolished objects.

  11. Aggregation behavior of sodium dioctylsulfosuccinate in aqueous ethylene glycol medium. A case of hydrogen bonding between surfactant and solvent and its manifestation in the surface tension isotherm.

    Science.gov (United States)

    Das, D; Dey, J; Chandra, A K; Thapa, U; Ismail, K

    2012-11-13

    The dependence of critical micelle concentration (cmc) of sodium dioctylsulfosuccinate (AOT) on the amount of ethylene glycol (EG) in water + EG medium was reported to be unusual and different from that of other surfactants to the extent that the cmc of AOT in EG is lower than in water. It is yet to be understood why AOT behaves so in water + EG medium, although AOT is known to have some special properties. Hence in the present study cmc of AOT in water + EG medium in the range from 0 to 100% (by weight) EG is measured by using surface tension and fluorescence emission methods. In contrast to what was reported, this study revealed that with respect to EG amount the cmc of AOT follows the general trend and AOT has higher cmc in EG than in water. On the other hand, it was surprisingly found that a break in the surface tension isotherm occurs in the premicellar region when the amount of EG exceeds 50% rendering a bisigmoidal shape to the surface tension isotherm. UV spectral study showed that AOT and EG undergo hydrogen bonding in the premicellar region when the EG amount is ≥50% and this hydrogen bonding becomes less on adding NaCl. The density functional theory calculations also showed formation of hydrogen bonds between EG and AOT through the sulfonate group of AOT providing thereby support to the experimental findings. The calculations predicted a highly stable AOT-EG-H(2)O trimer complex with a binding energy of -37.93 kcal mol(-1). The present system is an example, which is first of its kind, of a case where hydrogen bonding with surfactant and solvent molecules results in a surface tension break.

  12. Nuclear trafficking of secreted factors and cell-surface receptors: new pathways to regulate cell proliferation and differentiation, and involvement in cancers

    Directory of Open Access Journals (Sweden)

    Planque Nathalie

    2006-10-01

    Full Text Available Abstract Secreted factors and cell surface receptors can be internalized by endocytosis and translocated to the cytoplasm. Instead of being recycled or proteolysed, they sometimes translocate to the nucleus. Nuclear import generally involves a nuclear localization signal contained either in the secreted factor or its transmembrane receptor, that is recognized by the importins machinery. In the nucleus, these molecules regulate transcription of specific target genes by direct binding to transcription factors or general coregulators. In addition to the transcription regulation, nuclear secreted proteins and receptors seem to be involved in other important processes for cell life and cellular integrity such as DNA replication, DNA repair and RNA metabolism. Nuclear secreted proteins and transmembrane receptors now appear to induce new signaling pathways to regulate cell proliferation and differentiation. Their nuclear localization is often transient, appearing only during certain phases of the cell cycle. Nuclear secreted and transmembrane molecules regulate the proliferation and differentiation of a large panel of cell types during embryogenesis and adulthood and are also potentially involved in wound healing. Secreted factors such as CCN proteins, EGF, FGFs and their receptors are often detected in the nucleus of cancer cells. Nuclear localization of these molecules has been correlated with tumor progression and poor prognosis for patient survival. Nuclear growth factors and receptors may be responsible for resistance to radiotherapy.

  13. Glucose Evokes Rapid Ca2+ and Cyclic AMP Signals by Activating the Cell-Surface Glucose-Sensing Receptor in Pancreatic β-Cells

    Science.gov (United States)

    Nakagawa, Yuko; Nagasawa, Masahiro; Medina, Johan; Kojima, Itaru

    2015-01-01

    Glucose is a primary stimulator of insulin secretion in pancreatic β-cells. High concentration of glucose has been thought to exert its action solely through its metabolism. In this regard, we have recently reported that glucose also activates a cell-surface glucose-sensing receptor and facilitates its own metabolism. In the present study, we investigated whether glucose activates the glucose-sensing receptor and elicits receptor-mediated rapid actions. In MIN6 cells and isolated mouse β-cells, glucose induced triphasic changes in cytoplasmic Ca2+ concentration ([Ca2+]c); glucose evoked an immediate elevation of [Ca2+]c, which was followed by a decrease in [Ca2+]c, and after a certain lag period it induced large oscillatory elevations of [Ca2+]c. Initial rapid peak and subsequent reduction of [Ca2+]c were independent of glucose metabolism and reproduced by a nonmetabolizable glucose analogue. These signals were also blocked by an inhibitor of T1R3, a subunit of the glucose-sensing receptor, and by deletion of the T1R3 gene. Besides Ca2+, glucose also induced an immediate and sustained elevation of intracellular cAMP ([cAMP]c). The elevation of [cAMP]c was blocked by transduction of the dominant-negative Gs, and deletion of the T1R3 gene. These results indicate that glucose induces rapid changes in [Ca2+]c and [cAMP]c by activating the cell-surface glucose-sensing receptor. Hence, glucose generates rapid intracellular signals by activating the cell-surface receptor. PMID:26630567

  14. Surface-expressed insulin receptors as well as IGF-I receptors both contribute to the mitogenic effects of human insulin and its analogues

    DEFF Research Database (Denmark)

    Lundby, Anders; Bolvig, Pernille; Hegelund, Anne Charlotte

    2015-01-01

    therefore optimized mitogenicity assay conditions for a panel of five cell lines. All cell lines expressed insulin receptors (IR), IGF-I receptors (IGF-IR) and hybrid receptors, and in all cell lines, insulin as well as the comparator compounds X10 and IGF-I caused phosphorylation of the IR as well as IGF......There is a medical need for new insulin analogues. Yet, molecular alterations to the insulin molecule can theoretically result in analogues with carcinogenic effects. Preclinical carcinogenicity risk assessment for insulin analogues rests to a large extent on mitogenicity assays in cell lines. We......-IR. Insulin exhibited mitogenicity EC50 values in the single-digit nanomolar to picomolar range. We observed correlations across cell types between (i) mitogenic potency of insulin and IGF-IR/IR ratio, (ii) Akt phosphorylation and mitogenic potency and (iii) Akt phosphorylation and IR phosphorylation. Using...

  15. Glycoprotein IIb/IIIa and P2Y12 Induction by Oligochitosan Accelerates Platelet Aggregation

    Directory of Open Access Journals (Sweden)

    Mercy Halleluyah Periayah

    2014-01-01

    Full Text Available Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia is a receptor detected on platelets. Adenosine diphosphate (ADP activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C, and oligochitosan 53 (O-C 53]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%, followed by O-C (65.5 ± 7.17%. Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro.

  16. The receptor Slamf1 on the surface of myeloid lineage cells controls susceptibility to infection by Trypanosoma cruzi.

    Directory of Open Access Journals (Sweden)

    Jossela Calderón

    Full Text Available Trypanosoma cruzi, the protozoan parasite responsible for Chagas' disease, causes severe myocarditis often resulting in death. Here, we report that Slamf1-/- mice, which lack the hematopoietic cell surface receptor Slamf1, are completely protected from an acute lethal parasite challenge. Cardiac damage was reduced in Slamf1-/- mice compared to wild type mice, infected with the same doses of parasites, as a result of a decrease of the number of parasites in the heart even the parasitemia was only marginally less. Both in vivo and in vitro experiments reveal that Slamf1-defIcient myeloid cells are impaired in their ability to replicate the parasite and show altered production of cytokines. Importantly, IFN-γ production in the heart of Slamf1 deficient mice was much lower than in the heart of wt mice even though the number of infiltrating dendritic cells, macrophages, CD4 and CD8 T lymphocytes were comparable. Administration of an anti-Slamf1 monoclonal antibody also reduced the number of parasites and IFN-γ in the heart. These observations not only explain the reduced susceptibility to in vivo infection by the parasite, but they also suggest human Slamf1 as a potential target for therapeutic target against T. cruzi infection.

  17. Lectin receptors distribution in the surface membrane of Trypanosoma cruzi blood forms collected from mice submitted to specific treatment

    Directory of Open Access Journals (Sweden)

    Gilberto Fontes

    1991-09-01

    Full Text Available The author investigated the distribution of lectin receptors on Trypanosoma cruzi blood forms collected from mice inoculated with, respectively, the drug-resistant and drug-sensitive strains VL-10 and CL, and treated with the two standard active nitroheterocyclic compounds nifurtimox and benznidazole used for treatment of human Chagas' disease. Blood trypomastigotes purified in Fycoll-Hypaque were incubated with fluorescein-labelled lectins Con A, WGA, EE, WFA, TPA and PNA and then microscopically examined. Neither qualitative or quantitative differences in the fluorescence intensity could be detected between parasites from VL-10 and CL strains submitted or not to treatment. The results suggest that both strains do not differ in their surface membrane carbohydrate moieties. Moreover, the rapid clearance of blood forms the drug-sensitive strain in animals treated with singlo doses of both compounds is not likely to depend on membrane alterations expressed by changes in the carbohydrate components. furthermore, resistance or sensitivity to drugs is not apparently related to carbohydrate distribution on T. cruzi blood forms.

  18. Discrimination of different forms of the murine urokinase plasminogen activator receptor on the cell surface using monoclonal antibodies

    DEFF Research Database (Denmark)

    Rasch, M.G.; Pass, J.; Illemann, M.

    2008-01-01

    preformed complexes of murine pro-uPA and murine uPAR. In contrast, mR4 recognises domains II-III in uPAR and does not bind preformed pro-uPA-uPAR complexes in similar analyses. Immunofluorescence microscopy of P388D.1 cells revealed that mR3 stained the cells equally well in the presence or absence...... macrophage-like P388D.1 cells, we have now generated and characterised two high-affinity murine mAbs, mR3 and mR4, raised against murine uPAR. mR3 was found to recognise an epitope located in domain I of uPAR. Surface plasmon resonance analyses and cell binding studies revealed that this mAb was able to bind...... of saturation with the amino-terminal fragment of uPA, ATF. However, the signal intensity obtained using another uPAR domain I specific mAb, mR1, was significantly reduced upon ATF saturation. Furthermore, when adding ATF, mR4 selectively stained the cleaved receptor. Applying these newly generated mAbs, we...

  19. Migration of myeloid cells during inflammation is differentially regulated by the cell surface receptors Slamf1 and Slamf8.

    Directory of Open Access Journals (Sweden)

    Guoxing Wang

    Full Text Available Previous studies have demonstrated that the cell surface receptor Slamf1 (CD150 is requisite for optimal NADPH-oxidase (Nox2 dependent reactive oxygen species (ROS production by phagocytes in response to Gram- bacteria. By contrast, Slamf8 (CD353 is a negative regulator of ROS in response to Gram+ and Gram- bacteria. Employing in vivo migration after skin sensitization, induction of peritonitis, and repopulation of the small intestine demonstrates that in vivo migration of Slamf1-/- dendritic cells and macrophages is reduced, as compared to wt mice. By contrast, in vivo migration of Slamf8-/- dendritic cells, macrophages and neutrophils is accelerated. These opposing effects of Slamf1 and Slamf8 are cell-intrinsic as judged by in vitro migration in transwell chambers in response to CCL19, CCL21 or CSF-1. Importantly, inhibiting ROS production of Slamf8-/- macrophages by diphenyleneiodonium chloride blocks this in vitro migration. We conclude that Slamf1 and Slamf8 govern ROS-dependent innate immune responses of myeloid cells, thus modulating migration of these cells during inflammation in an opposing manner.

  20. Aggregated Computational Toxicology Online Resource

    Data.gov (United States)

    U.S. Environmental Protection Agency — Aggregated Computational Toxicology Online Resource (AcTOR) is EPA's online aggregator of all the public sources of chemical toxicity data. ACToR aggregates data...

  1. Amplification of anion sensing by disulfide functionalized ferrocene and ferrocene-calixarene receptors adsorbed onto gold surfaces.

    Science.gov (United States)

    Cormode, David P; Evans, Andrew J; Davis, Jason J; Beer, Paul D

    2010-07-28

    A disulfide functionalized bis-ferrocene urea acyclic receptor and disulfide functionalized mono- and bis-ferrocene amide and urea appended upper rim calix[4]arene receptors were prepared for the fabrication of SAM redox-active anion sensors. 1H NMR and diffusive voltammetric anion recognition investigations revealed each receptor to be capable of complexing and electrochemically sensing anions via cathodic perturbations of the respective receptor's ferrocene/ferrocenium redox couple. SAMs of a ferrocene urea receptor 3 and ferrocene urea calixarene receptor 17 exhibited significant enhanced magnitudes of cathodic response upon anion addition as compared to observed diffusive perturbations. SAMs of 17 were demonstrated to sense the perrhenate anion in aqueous solutions.

  2. Langmuir films of dipalmitoyl phosphatidylethanolamine grafted poly(ethylene glycol). In-situ evidence of surface aggregation at the air-water interface.

    Science.gov (United States)

    Clop, Eduardo M; Corvalán, Natalia A; Perillo, María A

    2016-12-01

    The molecular packing-dependent interfacial organization of polyethylene glycol grafted dipalmitoylphosphatidylethanolamine (PE-PEGs) Langmuir films was studied. The PEG chains covered a wide molecular mass range (350, 1000 and 5000Da). In surface pressure-area (π-A), isotherms PE-PEG(1000) and PE-PEG(5000) showed transitions (midpoints at πm,t1∼11mN/m, "t1"), which appeared as a long non-horizontal line region. Thus, t1 cannot be considered a first-order phase transition but may reflect a transition within the polymer, comprising its desorption from the air-water interface and compaction upon compression. This is supported by the increase in the νs(C-O-C) PM-IRRAS signal intensity and the increasing surface potentials at maximal compression, which reflect thicker polymeric layers. Furthermore, changes in hydrocarbon chain (HC) packing and tilt with respect to the surface led to reorientation in the PO2(-) group upon compression, indicated by the inversion of the νasym(PO2(-)) PM-IRRAS signal around t1. The absence of a t1 in PE-PEG(350) supports the requisite of a critical polymer chain length for this transition to occur. In-situ epifluorescence microscopy revealed 2D-domain-like structures in PE-PEG(1000) and PE-PEG(5000) around t1, possibly associated with gelation/dehydration of the polymeric layer and appearing at decreasing π as the polymeric tail became longer. Another transition, t2, appearing in PE-PEG(350) and PE-PEG(1000) at πm,t2=29.4 and 34.8mN/m, respectively, was associated with HC condensation and was impaired in PE-PEG(5000) due to steric hindrance imposed by the large size of its polymer moiety. Two critical lengths of polymer chains were found, one of which allowed the onset of polymeric-tail gelation and the other limited HC compaction. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Area-averaged evapotranspiration over a heterogeneous land surface: aggregation of multi-point EC flux measurements with a high-resolution land-cover map and footprint analysis

    Directory of Open Access Journals (Sweden)

    F. Xu

    2017-08-01

    Full Text Available The determination of area-averaged evapotranspiration (ET at the satellite pixel scale/model grid scale over a heterogeneous land surface plays a significant role in developing and improving the parameterization schemes of the remote sensing based ET estimation models and general hydro-meteorological models. The Heihe Watershed Allied Telemetry Experimental Research (HiWATER flux matrix provided a unique opportunity to build an aggregation scheme for area-averaged fluxes. On the basis of the HiWATER flux matrix dataset and high-resolution land-cover map, this study focused on estimating the area-averaged ET over a heterogeneous landscape with footprint analysis and multivariate regression. The procedure is as follows. Firstly, quality control and uncertainty estimation for the data of the flux matrix, including 17 eddy-covariance (EC sites and four groups of large-aperture scintillometers (LASs, were carefully done. Secondly, the representativeness of each EC site was quantitatively evaluated; footprint analysis was also performed for each LAS path. Thirdly, based on the high-resolution land-cover map derived from aircraft remote sensing, a flux aggregation method was established combining footprint analysis and multiple-linear regression. Then, the area-averaged sensible heat fluxes obtained from the EC flux matrix were validated by the LAS measurements. Finally, the area-averaged ET of the kernel experimental area of HiWATER was estimated. Compared with the formerly used and rather simple approaches, such as the arithmetic average and area-weighted methods, the present scheme is not only with a much better database, but also has a solid grounding in physics and mathematics in the integration of area-averaged fluxes over a heterogeneous surface. Results from this study, both instantaneous and daily ET at the satellite pixel scale, can be used for the validation of relevant remote sensing models and land surface process models. Furthermore, this

  4. Galectin-3 induces clustering of CD147 and integrin-β1 transmembrane glycoprotein receptors on the RPE cell surface.

    Directory of Open Access Journals (Sweden)

    Claudia S Priglinger

    Full Text Available Proliferative vitreoretinopathy (PVR is a blinding disease frequently occurring after retinal detachment surgery. Adhesion, migration and matrix remodeling of dedifferentiated retinal pigment epithelial (RPE cells characterize the onset of the disease. Treatment options are still restrained and identification of factors responsible for the abnormal behavior of the RPE cells will facilitate the development of novel therapeutics. Galectin-3, a carbohydrate-binding protein, was previously found to inhibit attachment and spreading of retinal pigment epithelial cells, and thus bares the potential to counteract PVR-associated cellular events. However, the identities of the corresponding cell surface glycoprotein receptor proteins on RPE cells are not known. Here we characterize RPE-specific Gal-3 containing glycoprotein complexes using a proteomic approach. Integrin-β1, integrin-α3 and CD147/EMMPRIN, a transmembrane glycoprotein implicated in regulating matrix metalloproteinase induction, were identified as potential Gal-3 interactors on RPE cell surfaces. In reciprocal immunoprecipitation experiments we confirmed that Gal-3 associated with CD147 and integrin-β1, but not with integrin-α3. Additionally, association of Gal-3 with CD147 and integrin-β1 was observed in co-localization analyses, while integrin-α3 only partially co-localized with Gal-3. Blocking of CD147 and integrin-β1 on RPE cell surfaces inhibited binding of Gal-3, whereas blocking of integrin-α3 failed to do so, suggesting that integrin-α3 is rather an indirect interactor. Importantly, Gal-3 binding promoted pronounced clustering and co-localization of CD147 and integrin-β1, with only partial association of integrin-α3. Finally, we show that RPE derived CD147 and integrin-β1, but not integrin-α3, carry predominantly β-1,6-N-actyl-D-glucosamine-branched glycans, which are high-affinity ligands for Gal-3. We conclude from these data that extracellular Gal-3 triggers

  5. Galectin-3 induces clustering of CD147 and integrin-β1 transmembrane glycoprotein receptors on the RPE cell surface.

    Science.gov (United States)

    Priglinger, Claudia S; Szober, Christoph M; Priglinger, Siegfried G; Merl, Juliane; Euler, Kerstin N; Kernt, Marcus; Gondi, Gabor; Behler, Jennifer; Geerlof, Arie; Kampik, Anselm; Ueffing, Marius; Hauck, Stefanie M

    2013-01-01

    Proliferative vitreoretinopathy (PVR) is a blinding disease frequently occurring after retinal detachment surgery. Adhesion, migration and matrix remodeling of dedifferentiated retinal pigment epithelial (RPE) cells characterize the onset of the disease. Treatment options are still restrained and identification of factors responsible for the abnormal behavior of the RPE cells will facilitate the development of novel therapeutics. Galectin-3, a carbohydrate-binding protein, was previously found to inhibit attachment and spreading of retinal pigment epithelial cells, and thus bares the potential to counteract PVR-associated cellular events. However, the identities of the corresponding cell surface glycoprotein receptor proteins on RPE cells are not known. Here we characterize RPE-specific Gal-3 containing glycoprotein complexes using a proteomic approach. Integrin-β1, integrin-α3 and CD147/EMMPRIN, a transmembrane glycoprotein implicated in regulating matrix metalloproteinase induction, were identified as potential Gal-3 interactors on RPE cell surfaces. In reciprocal immunoprecipitation experiments we confirmed that Gal-3 associated with CD147 and integrin-β1, but not with integrin-α3. Additionally, association of Gal-3 with CD147 and integrin-β1 was observed in co-localization analyses, while integrin-α3 only partially co-localized with Gal-3. Blocking of CD147 and integrin-β1 on RPE cell surfaces inhibited binding of Gal-3, whereas blocking of integrin-α3 failed to do so, suggesting that integrin-α3 is rather an indirect interactor. Importantly, Gal-3 binding promoted pronounced clustering and co-localization of CD147 and integrin-β1, with only partial association of integrin-α3. Finally, we show that RPE derived CD147 and integrin-β1, but not integrin-α3, carry predominantly β-1,6-N-actyl-D-glucosamine-branched glycans, which are high-affinity ligands for Gal-3. We conclude from these data that extracellular Gal-3 triggers clustering of CD147 and

  6. Recycled aggregates concrete: aggregate and mix properties

    Directory of Open Access Journals (Sweden)

    González-Fonteboa, B.

    2005-09-01

    Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

    Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

  7. Protein Colloidal Aggregation Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J. (Compiler)

    2014-01-01

    To investigate the pathways and kinetics of protein aggregation to allow accurate predictive modeling of the process and evaluation of potential inhibitors to prevalent diseases including cataract formation, chronic traumatic encephalopathy, Alzheimer's Disease, Parkinson's Disease and others.

  8. Seasonal variability of soil aggregate stability

    Science.gov (United States)

    Rohoskova, M.; Kodesova, R.; Jirku, V.; Zigova, A.; Kozak, J.

    2009-04-01

    Seasonal variability of soil properties measured in surface horizons of three soil types (Haplic Luvisol, Greyic Phaeozem, Haplic Cambisol) was studied in years 2007 and 2008. Undisturbed and disturbed soil samples were taken every month to evaluate field water content, bulk density, porosity, ration of gravitational and capillary pores, pHKCl and pHH2O, organic matter content and its quality, aggregate stability using WSA index. In addition, micromorphological features of soil aggregates were studied in thin soil sections that were made from undisturbed large soil aggregates. Results showed that soil aggregate stability depended on stage of the root zone development, soil management and climatic conditions. Larger aggregate stabilities and also larger ranges of measure values were obtained in the year 2007 then those measured in 2008. This was probably caused by lower precipitations and consequently lower soil water contents observed in 2007 than those measured in 2008. The highest aggregate stability was measured at the end of April in the years 2007 and 2008 in Haplic Luvisol and Greyic Phaeozem, and at the end of June in the year 2007 and at the beginning of June in 2008 in Haplic Cambisol. In all cases aggregate stability increased during the root growth and then gradually decreased due to summer rainfall events. Aggregate stability reflected aggregate structure and soil pore system development, which was documented on micromorphological images and evaluated using the ration of gravitational and capillary pores measured on the undisturbed sol samples. Acknowledgement: Authors acknowledge the financial support of the Grant Agency of the Czech Republic grant No. 526/08/0434, and the Ministry of Education, Youth and Sports grant No. MSM 6046070901.

  9. Aggregation of retail stores

    Science.gov (United States)

    Jensen, Pablo; Boisson, Jean; Larralde, Hernán

    2005-06-01

    We propose a simple model to understand the economic factors that induce aggregation of some businesses over small geographical regions. The model incorporates price competition with neighboring stores, transportation costs and the satisfaction probability of finding the desired product. We show that aggregation is more likely for stores selling expensive products and/or stores carrying only a fraction of the business variety. We illustrate our model with empirical data collected in the city of Lyon.

  10. PPARγ ligands decrease hydrostatic pressure-induced platelet aggregation and proinflammatory activity.

    Directory of Open Access Journals (Sweden)

    Fang Rao

    Full Text Available Hypertension is known to be associated with platelet overactivity, but the direct effects of hydrostatic pressure on platelet function remain unclear. The present study sought to investigate whether elevated hydrostatic pressure is responsible for platelet activation and to address the potential role of peroxisome proliferator-activated receptor-γ (PPARγ. We observed that hypertensive patients had significantly higher platelet volume and rate of ADP-induced platelets aggregation compared to the controls. In vitro, Primary human platelets were cultured under standard (0 mmHg or increased (120, 180, 240 mmHg hydrostatic pressure for 18 h. Exposure to elevated pressure was associated with morphological changes in platelets. Platelet aggregation and PAC-1 (the active confirmation of GPIIb/IIIa binding were increased, CD40L was translocated from cytoplasm to the surface of platelet and soluble CD40L (sCD40L was released into the medium in response to elevated hydrostatic pressure (180 and 240 mmHg. The PPARγ activity was up-regulated as the pressure was increased from 120 mmHg to 180 mmHg. Pressure-induced platelet aggregation, PAC-1 binding, and translocation and release of CD40L were all attenuated by the PPARγ agonist Thiazolidinediones (TZDs. These results demonstrate that platelet activation and aggregation are increased by exposure to elevated pressure and that PPARγ may modulate platelet activation induced by high hydrostatic pressure.

  11. On the friction coefficient of straight-chain aggregates.

    Science.gov (United States)

    Isella, Lorenzo; Drossinos, Yannis

    2011-04-15

    A methodology to calculate the friction coefficient of an aggregate in the continuum regime is proposed. The friction coefficient and the monomer shielding factors, aggregate-average or individual, are related to the molecule-aggregate collision rate that is obtained from the molecular diffusion equation with an absorbing boundary condition on the aggregate surface. Calculated friction coefficients of straight chains are in very good agreement with previous results, suggesting that the friction coefficients may be accurately calculated from the product of the collision rate and an average momentum transfer, the latter being independent of aggregate morphology. Langevin-dynamics simulations show that the diffusive motion of straight-chain aggregates may be described either by a monomer-dependent or an aggregate-average random force, if the shielding factors are appropriately chosen. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Generation of Soluble Advanced Glycation End Products Receptor (sRAGE)-Binding Ligands during Extensive Heat Treatment of Whey Protein/Lactose Mixtures Is Dependent on Glycation and Aggregation

    NARCIS (Netherlands)

    Liu, Fahui; Teodorowicz, Gosia; Wichers, Harry J.; Boekel, van Tiny; Hettinga, Kasper A.

    2016-01-01

    Heating of protein- and sugar-containing materials is considered the primary factor affecting the formation of advanced glycation end products (AGEs). This study aimed to investigate the influence of heating conditions, digestion, and aggregation on the binding capacity of AGEs to the soluble AGE

  13. Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol.

    Science.gov (United States)

    Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

    2016-12-13

    Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5-2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared.

  14. Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol

    Science.gov (United States)

    Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

    2016-12-01

    Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5-2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared.

  15. Enhancement of the adsorption capacity of the light-weight expanded clay aggregate surface for the metronidazole antibiotic by coating with MgO nanoparticles: Studies on the kinetic, isotherm, and effects of environmental parameters.

    Science.gov (United States)

    Kalhori, Ebrahim Mohammadi; Al-Musawi, Tariq J; Ghahramani, Esmaeil; Kazemian, Hossein; Zarrabi, Mansur

    2017-05-01

    The synthesized MgO nanoparticles were used to coat the light-weight expanded clay aggregates (LECA) and as a metronidazole (MNZ) adsorbent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transformed infrared (FTIR) techniques were employed to study the surface morphology and characteristics of the adsorbents. MgO/LECA clearly revealed the advantages of the nanocomposite particles, showing high specific surface area (76.12 m2/g), significant adsorption sites and functional groups. Between pH 5 and 9, the MNZ sorption was not significantly affected. Kinetic studies revealed that the MNZ adsorption closely followed the Avrami model, with no dominant process controlling the sorption rate. The study of the effects of foreign ions revealed that the addition of carbonate raised the MNZ removal efficiency of LECA by 8% and the total removal of MNZ by MgO/LECA. Furthermore, nitrate and hardness only marginally influenced the MNZ removal efficiency and their effects can be ranked in the order of carbonate>nitrate>hardness. The isotherm adsorption of MNZ was best fitted with the Langmuir model enlighten the monolayer MNZ adsorption on the homogeneous LECA and MgO/LECA surfaces. The maximum adsorption capacity under optimum conditions was enhanced from 56.31 to 84.55 mg/g for LECA and MgO/LECA, respectively. These findings demonstrated that the MgO/LECA nanocomposite showed potential as an efficient adsorbent for MNZ removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Differential surface density and modulatory effects of presynaptic GABAB receptors in hippocampal cholecystokinin and parvalbumin basket cells.

    Science.gov (United States)

    Booker, Sam A; Althof, Daniel; Degro, Claudius E; Watanabe, Masahiko; Kulik, Ákos; Vida, Imre

    2017-11-01

    The perisomatic domain of cortical neurons is under the control of two major GABAergic inhibitory interneuron types: regular-spiking cholecystokinin (CCK) basket cells (BCs) and fast-spiking parvalbumin (PV) BCs. CCK and PV BCs are different not only in their intrinsic physiological, anatomical and molecular characteristics, but also in their presynaptic modulation of their synaptic output. Most GABAergic terminals are known to contain GABAB receptors (GABABR), but their role in presynaptic inhibition and surface expression have not been comparatively characterized in the two BC types. To address this, we performed whole-cell recordings from CCK and PV BCs and postsynaptic pyramidal cells (PCs), as well as freeze-fracture replica-based quantitative immunogold electron microscopy of their synapses in the rat hippocampal CA1 area. Our results demonstrate that while both CCK and PV BCs contain functional presynaptic GABABRs, their modulatory effects and relative abundance are markedly different at these two synapses: GABA release is dramatically inhibited by the agonist baclofen at CCK BC synapses, whereas a moderate reduction in inhibitory transmission is observed at PV BC synapses. Furthermore, GABABR activation has divergent effects on synaptic dynamics: paired-pulse depression (PPD) is enhanced at CCK BC synapses, but abolished at PV BC synapses. Consistent with the quantitative differences in presynaptic inhibition, virtually all CCK BC terminals were found to contain GABABRs at high densities, but only 40% of PV BC axon terminals contain GABABRs at detectable levels. These findings add to an increasing list of differences between these two interneuron types, with implications for their network functions.

  17. Group A streptococcal surface GAPDH, SDH, recognizes uPAR/CD87 as its receptor on the human pharyngeal cell and mediates bacterial adherence to host cells.

    Science.gov (United States)

    Jin, Hong; Song, Youngmia P; Boel, Gregory; Kochar, Jaspreet; Pancholi, Vijay

    2005-07-01

    Streptococcal surface dehydrogenase (SDH) is a multifunctional, anchorless protein present on the surface of group A Streptococcus (GAS). It plays a regulatory role in GAS-mediated intracellular signaling events in human pharyngeal cells. Using ligand-binding assays, we have identified an approximately 55 kDa protein as an SDH-specific receptor protein on the surface of Detroit human pharyngeal cells. LC-MS/MS analyses identified this SDH-binding pharyngeal cell-surface-exposed membrane-bound protein as uPAR (urokinase plasminogen activator receptor)/CD87. Ligand-binding assays also revealed that only the N-terminal domain (D1) of uPAR bound to SDH. uPAR-D1 more specifically bound to the C-terminal alpha-helix and two immediate flanking regions of the S-loop of the SDH molecule. Site-directed mutagenesis in GAS resulting in SDH with altered C-terminal ends, and the removal of uPAR from pharyngeal cells by phosphatidylinositol-phopsholipase C treatment decreased GAS ability to adhere to pharyngeal cells. When compared to uninfected Detroit pharyngeal cells, GAS-infected pharyngeal cells showed a transient but a significant increase in the expression of uPAR-specific mRNA, and a prolonged recycling process of uPAR on the cell surface. Together, these results indicate that the specific streptococcal surface protein-pharyngeal cell receptor interaction mediated by SDH and uPAR is modulated during GAS infection of human pharyngeal cells. This interaction significantly contributes to bacterial adherence and thus may play a significant role in GAS pathogenesis by regulating intracellular signaling events in pharyngeal cells.

  18. Observing Convective Aggregation

    Science.gov (United States)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-11-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  19. Observing Convective Aggregation

    Science.gov (United States)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-06-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  20. The use of expanded clay aggregate for the pretreatment of surface waters on the example of a tributary of Lake Klasztorne Górne in Strzelce Krajeńskie

    Directory of Open Access Journals (Sweden)

    Łopata Michał

    2017-03-01

    Full Text Available The paper presents a proposal for the treatment of river water based on expanded clay (ceramsite. It is a lightweight mineral aggregate containing components relative to phosphorus adsorption (calcium, iron, manganese, aluminum. A pilot plant on a fractional technical scale was built on a nutrient rich (phosphorus up to 0.4 mg dm−3, nitrogen up to 10.0 mg dm−3, small (mean annual flow about 0.04 m3 s−1, natural watercourse (Młynówka River, a tributary of the Otok Channel, Noteć basin, the municipality of Strzelce Krajeńskie. The monitoring included quantitative and qualitative measurements of the water stream in 2014-2015. On the basis of the examinations, the calculated effectiveness of ceramsite filters in removing major contaminants from water was: for total nitrogen 5-6%, phosphorus 12-16%, and for suspensions 17-29%. The effectiveness of the treatment is highly influenced by hydraulic load, so this type application on a full-scale should occupy a sufficiently large volume. Taking into account simplicity of performance, ease of operation and low cost of construction and maintenance, such pretreatment plants based on expanded clay would seem to be a promising tool for the protection of surface waters in catchments of small rivers and streams.

  1. Analysis of the interaction between human interleukin-5 and the soluble domain of its receptor using a surface plasmon resonance biosensor.

    Science.gov (United States)

    Morton, T A; Bennett, D B; Appelbaum, E R; Cusimano, D M; Johanson, K O; Matico, R E; Young, P R; Doyle, M; Chaiken, I M

    1994-03-01

    A surface plasmon resonance (SPR) biosensor was used to study the interaction of human interleukin-5 (hIL5) with its receptor. IL5 is a major growth factor in the production and activation of eosinophils. The receptor for IL5 is composed of two subunits, alpha and beta. The alpha subunit provides the specificity for IL5 and consists of an extracellular soluble domain, a single transmembrane region and a cytoplasmic tail. We expressed the soluble domain of the human IL5 receptor alpha subunit (shIL5R alpha) and human IL5 (hIL5) in Drosophila. Both hIL5 and shIL5R alpha were immobilized separately through amine groups onto the carboxylated dextran layer of sensor chips of the BIAcore (Pharmacia) SPR biosensor after N-hydroxysuccinimide/carbodiimide activation of the chip surface. Interactions were measured for the complementary macromolecule, either shIL5R alpha or hIL5, in solution. Kinetics of binding of soluble analyte to immobilized ligand were measured and from this the association rate constant, dissociation rate constant and equilibrium dissociation constant (Kd) were derived. With immobilized shIL5R alpha and soluble hIL5, the measured Kd was 2 nM. A similar value was obtained by titration calorimetry. The Kd for Drosophila expressed receptor and IL5 is higher than the values reported for proteins expressed in different systems, likely due to differences in the methods of interaction analysis used or differences in protein glycosylation. Receptor-IL5 binding was relatively pH independent between pH 6.5 and 9.5. Outside this range, the dissociation rate increased with comparatively little increase in association rate.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Receptor sequestration in response to β-arrestin-2 phosphorylation by ERK1/2 governs steady-state levels of GPCR cell-surface expression.

    Science.gov (United States)

    Paradis, Justine S; Ly, Stevenson; Blondel-Tepaz, Élodie; Galan, Jacob A; Beautrait, Alexandre; Scott, Mark G H; Enslen, Hervé; Marullo, Stefano; Roux, Philippe P; Bouvier, Michel

    2015-09-15

    MAPKs are activated in response to G protein-coupled receptor (GPCR) stimulation and play essential roles in regulating cellular processes downstream of these receptors. However, very little is known about the reciprocal effect of MAPK activation on GPCRs. To investigate possible crosstalk between the MAPK and GPCRs, we assessed the effect of ERK1/2 on the activity of several GPCR family members. We found that ERK1/2 activation leads to a reduction in the steady-state cell-surface expression of many GPCRs because of their intracellular sequestration. This subcellular redistribution resulted in a global dampening of cell responsiveness, as illustrated by reduced ligand-mediated G-protein activation and second-messenger generation as well as blunted GPCR kinases and β-arrestin recruitment. This ERK1/2-mediated regulatory process was observed for GPCRs that can interact with β-arrestins, such as type-2 vasopressin, type-1 angiotensin, and CXC type-4 chemokine receptors, but not for the prostaglandin F receptor that cannot interact with β-arrestin, implicating this scaffolding protein in the receptor's subcellular redistribution. Complementation experiments in mouse embryonic fibroblasts lacking β-arrestins combined with in vitro kinase assays revealed that β-arrestin-2 phosphorylation on Ser14 and Thr276 is essential for the ERK1/2-promoted GPCR sequestration. This previously unidentified regulatory mechanism was observed after constitutive activation as well as after receptor tyrosine kinase- or GPCR-mediated activation of ERK1/2, suggesting that it is a central node in the tonic regulation of cell responsiveness to GPCR stimulation, acting both as an effector and a negative regulator.

  3. Single residues in the surface subunits of oncogenic sheep retrovirus envelopes distinguish receptor-mediated triggering for fusion at low pH and infection

    Energy Technology Data Exchange (ETDEWEB)

    Cote, Marceline [Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada H3A 2B4 (Canada); Zheng, Yi-Min [Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211-7310 (United States); Albritton, Lorraine M. [Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163 (United States); Liu, Shan-Lu, E-mail: liushan@missouri.edu [Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada H3A 2B4 (Canada); Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211-7310 (United States)

    2011-12-20

    Jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV) are two closely related oncogenic retroviruses that share the same cellular receptor yet exhibit distinct fusogenicity and infectivity. Here, we find that the low fusogenicity of ENTV envelope protein (Env) is not because of receptor binding, but lies in its intrinsic insensitivity to receptor-mediated triggering for fusion at low pH. Distinct from JSRV, shedding of ENTV surface (SU) subunit into culture medium was not enhanced by a soluble form of receptor, Hyal2 (sHyal2), and sHyal2 was unable to effectively inactivate the ENTV pseudovirions. Remarkably, replacing either of the two amino acid residues, N191 or S195, located in the ENTV SU with the corresponding JSRV residues, H191 or G195, markedly increased the Env-mediated membrane fusion activity and infection. Reciprocal amino acid substitutions also partly switched the sensitivities of ENTV and JSRV pseudovirions to sHyal2-mediated SU shedding and inactivation. While N191 is responsible for an extra N-linked glycosylation of ENTV SU relative to that of JSRV, S195 possibly forms a hydrogen bond with a surrounding amino acid residue. Molecular modeling of the pre-fusion structure of JSRV Env predicts that the segment of SU that contains H191 to G195 contacts the fusion peptide and suggests that the H191N and G195S changes seen in ENTV may stabilize its pre-fusion structure against receptor priming and therefore modulate fusion activation by Hyal2. In summary, our study reveals critical determinants in the SU subunits of JSRV and ENTV Env proteins that likely regulate their local structures and thereby differential receptor-mediated fusion activation at low pH, and these findings explain, at least in part, their distinct viral infectivity.

  4. Quantifying Dictyostelium discoideum Aggregation

    Science.gov (United States)

    McCann, Colin; Kriebel, Paul; Parent, Carole; Losert, Wolfgang

    2008-03-01

    Upon nutrient deprivation, the social amoebae Dictyostelium discoideum enter a developmental program causing them to aggregate into multicellular organisms. During this process cells sense and secrete chemical signals, often moving in a head-to-tail fashion called a `stream' as they assemble into larger entities. We measure Dictyostelium speed, shape, and directionality, both inside and outside of streams, and develop methods to distinguish group dynamics from behavior of individual cells. We observe an overall increase in speed during aggregation and a decrease in speed fluctuations once a cell joins a stream. Initial results indicate that when cells are in close proximity the trailing cells migrate specifically toward the backs of leading cells.

  5. Characterization of the specific interaction between the DNA aptamer sgc8c and protein tyrosine kinase-7 receptors at the surface of T-cells by biosensing AFM.

    Science.gov (United States)

    Leitner, Michael; Poturnayova, Alexandra; Lamprecht, Constanze; Weich, Sabine; Snejdarkova, Maja; Karpisova, Ivana; Hianik, Tibor; Ebner, Andreas

    2017-04-01

    We studied the interaction of the specific DNA aptamer sgc8c immobilized at the AFM tip with its corresponding receptor, the protein tyrosine kinase-7 (PTK7) embedded in the membrane of acute lymphoblastic leukemia (ALL) cells (Jurkat T-cells). Performing single molecule force spectroscopy (SMFS) experiments, we showed that the aptamer sgc8c bound with high probability (38.3 ± 7.48%) and high specificity to PTK7, as demonstrated by receptor blocking experiments and through comparison with the binding behavior of a nonspecific aptamer. The determined kinetic off-rate (koff = 5.16 s-1) indicates low dissociation of the sgc8c-PTK7 complex. In addition to the pulling force experiments, simultaneous topography and recognition imaging (TREC) experiments using AFM tips functionalized with sgc8c aptamers were realized on the outer regions surface of surface-immobilized Jurkat cells for the first time. This allowed determination of the distribution of PTK7 without any labeling and at near physiological conditions. As a result, we could show a homogeneous distribution of PTK7 molecules on the outer regions of ALL cells with a surface density of 325 ± 12 PTK7 receptors (or small receptor clusters) per μm2. Graphical Abstract The specific interaction of the DNA aptamer sgc8c and protein tyrosine kinase-7 (PTK7) on acute lymphoblastic leukemia (ALL) cells was characterized. AFM based single molecule force spectroscopy (SMFS) yielded a kinetic off-rate of 5.16 s-1 of the complex. Simultaneous topography and recognition imaging (TREC) revealed a PTK7 density of 325 ± 12 molecules or clusters per μm2 in the cell membrane.

  6. Xanthomonas citri subsp. citri surface proteome by 2D-DIGE: Ferric enterobactin receptor and other outer membrane proteins potentially involved in citric host interaction.

    Science.gov (United States)

    Carnielli, Carolina Moretto; Artier, Juliana; de Oliveira, Julio Cezar Franco; Novo-Mansur, Maria Teresa Marques

    2017-01-16

    Xanthomonas citri subsp. citri (XAC) is the causative agent of citrus canker, a disease of great economic impact around the world. Understanding the role of proteins on XAC cellular surface can provide new insights on pathogen-plant interaction. Surface proteome was performed in XAC grown in vivo (infectious) and in vitro (non-infectious) conditions, by labeling intact cells followed by cellular lysis and direct 2D-DIGE analysis. Seventy-nine differential spots were analyzed by mass spectrometry. Highest relative abundance for in vivo condition was observed for spots containing DnaK protein, 60kDa chaperonin, conserved hypothetical proteins, malate dehydrogenase, phosphomannose isomerase, and ferric enterobactin receptors. Elongation factor Tu, OmpA-related proteins, Oar proteins and some Ton-B dependent receptors were found in spots decreased in vivo. Some proteins identified on XAC's surface in infectious condition and predicted to be cytoplasmic, such as DnaK and 60KDa chaperonin, have also been previously found at cellular surface in other microorganisms. This is the first study on XAC surface proteome and results point to mediation of molecular chaperones in XAC-citrus interaction. The approach utilized here can be applied to other pathogen-host interaction systems and help to achieve new insights in bacterial pathogenicity toward promising targets of biotechnological interest. This research provides new insights for current knowledge of the Xanthomonas sp. pathogenicity. For the first time the 2D-DIGE approach was applied on intact cells to find surface proteins involved in the pathogen-plant interaction. Results point to the involvement of new surface/outer membrane proteins in the interaction between XAC and its citrus host and can provide potential targets of biotechnological interest for citrus canker control. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Depression is associated with an increase in the expression of the platelet adhesion receptor glycoprotein Ib.

    Science.gov (United States)

    Walsh, Marie-Thérèse; Dinan, Timothy G; Condren, Rita M; Ryan, Martina; Kenny, Dermot

    2002-05-17

    There is a significant association between cardiovascular disease and depression. Previous studies have documented changes in platelets in depression. It is unknown if depression causes functional changes in platelet surface receptors. Therefore, we analyzed (1) the surface expression of glycoprotein (GP)Ib and the integrin receptor alpha(IIb)beta(IIIa), receptors involved in platelet adhesion and aggregation, (2) CD62 (P-selectin) and CD63, integral granule proteins translocated during platelet activation, (3) platelet aggregation in response to ADP and (4) plasma levels of glycocalicin and von Willebrand factor (vWF), in depressed patients compared to healthy volunteers. Fifteen depressed patients with a Hamilton depression score of at least 22 and fifteen control subjects were studied. Platelets were assessed for surface expression levels of GPIb, alpha(IIb)beta(IIIa), CD62 and CD63 by flow cytometry. Genomic DNA was isolated to investigate a recently described polymorphism in the 5' untranslated region of the GPIbalpha gene. The number of GPIb receptors was significantly increased on the surface of platelets from patients with depression compared to control subjects. Surface expression of CD62 was also significantly increased in the depressed patients versus control subjects. There was no significant difference between depressed patients and healthy volunteers in the surface expression of alpha(IIb)beta(IIIa) or CD63, or in glycocalicin or vWF plasma concentration, or ADP-induced aggregation. There was no difference in allele frequency of the Kozak region polymorphism of the GPIbalpha gene, which can affect GPIb expression. The results of this study demonstrate that the number of GPIb receptors on platelets are increased in depression and suggest a novel risk factor for thrombosis in patients with depression.

  8. Novel Aggregation Promoting Factor AggE Contributes to the Probiotic Properties of Enterococcus faecium BGGO9-28

    Directory of Open Access Journals (Sweden)

    Katarina Veljović

    2017-09-01

    Full Text Available The understanding of mechanisms of interactions between various bacterial cell surface proteins and host receptors has become imperative for the study of the health promoting features of probiotic enterococci. This study, for the first time, describes a novel enterococcal aggregation protein, AggE, from Enterococcus faecium BGGO9-28, selected from a laboratory collection of enterococcal isolates with auto-aggregation phenotypes. Among them, En. faecium BGGO9-28 showed the strongest auto-aggregation, adhesion to components of ECM and biofilm formation. Novel aggregation promoting factor AggE, a protein of 178.1 kDa, belongs to the collagen-binding superfamily of proteins and shares similar architecture with previously discovered aggregation factors from lactic acid bacteria (LAB. Its expression in heterologous enterococcal and lactococcal hosts demonstrates that the aggE gene is sufficient for cell aggregation. The derivatives carrying aggE exhibited the ten times higher adhesion ability to collagen and fibronectin, possess about two times higher adhesion to mucin and contribute to the increase of biofilm formation, comparing to the control strains. Analysis for the presence of virulence factors (cytolysin and gelatinase production, antibiotic resistance (antibiotic susceptibility and genes (cylA, agg, gelE, esp, hylN, ace, efaAfs, and efaAfm showed that BGGO9-28 was sensitive to all tested antibiotics, without hemolytic or gelatinase activity. This strain does not carry any of the tested genes encoding for known virulence factors. Results showed that BGGO9-28 was resistant to low pH and high concentrations of bile salts. Also, it adhered strongly to the Caco-2 human epithelial cell line. In conclusion, the results of this study indicate that the presence of AggE protein on the cell surface in enterococci is a desirable probiotic feature.

  9. Aggregates, broccoli and cauliflower

    Science.gov (United States)

    Grey, Francois; Kjems, Jørgen K.

    1989-09-01

    Naturally grown structures with fractal characters like broccoli and cauliflower are discussed and compared with DLA-type aggregates. It is suggested that the branching density can be used to characterize the growth process and an experimental method to determine this parameter is proposed.

  10. Towards General Temporal Aggregation

    DEFF Research Database (Denmark)

    Boehlen, Michael H.; Gamper, Johann; Jensen, Christian Søndergaard

    2008-01-01

    Most database applications manage time-referenced, or temporal, data. Temporal data management is difficult when using conventional database technology, and many contributions have been made for how to better model, store, and query temporal data. Temporal aggregation illustrates well the problem...

  11. Improvement of Ligand Affinity and Thermodynamic Properties by NMR-Based Evaluation of Local Dynamics and Surface Complementarity in the Receptor-Bound State.

    Science.gov (United States)

    Mizukoshi, Yumiko; Takeuchi, Koh; Arutaki, Misa; Tokunaga, Yuji; Takizawa, Takeshi; Hanzawa, Hiroyuki; Shimada, Ichio

    2016-11-14

    The thermodynamic properties of a ligand in the bound state affect its binding specificity. Strict binding specificity can be achieved by introducing multiple spatially defined interactions, such as hydrogen bonds and van der Waals interactions, into the ligand-receptor interface. These introduced interactions are characterized by restricted local dynamics and improved surface complementarity in the bound state. In this study, we experimentally evaluated the local dynamics and the surface complementarity of weak-affinity ligands in the receptor-bound state by forbidden coherence transfer analysis in free-bound exchange systems (Ex-FCT), using the interaction between a ligand, a myocyte-enhancer factor 2A (MEF2A) docking peptide, and a receptor, p38α, as a model system. The Ex-FCT analyses successfully provided information for the rational design of a ligand with higher affinity and preferable thermodynamic properties for p38α. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Structural characterization of S100A15 reveals a novel zinc coordination site among S100 proteins and altered surface chemistry with functional implications for receptor binding

    Directory of Open Access Journals (Sweden)

    Murray Jill I

    2012-07-01

    Full Text Available Abstract Background S100 proteins are a family of small, EF-hand containing calcium-binding signaling proteins that are implicated in many cancers. While the majority of human S100 proteins share 25-65% sequence similarity, S100A7 and its recently identified paralog, S100A15, display 93% sequence identity. Intriguingly, however, S100A7 and S100A15 serve distinct roles in inflammatory skin disease; S100A7 signals through the receptor for advanced glycation products (RAGE in a zinc-dependent manner, while S100A15 signals through a yet unidentified G-protein coupled receptor in a zinc-independent manner. Of the seven divergent residues that differentiate S100A7 and S100A15, four cluster in a zinc-binding region and the remaining three localize to a predicted receptor-binding surface. Results To investigate the structural and functional consequences of these divergent clusters, we report the X-ray crystal structures of S100A15 and S100A7D24G, a hybrid variant where the zinc ligand Asp24 of S100A7 has been substituted with the glycine of S100A15, to 1.7 Å and 1.6 Å resolution, respectively. Remarkably, despite replacement of the Asp ligand, zinc binding is retained at the S100A15 dimer interface with distorted tetrahedral geometry and a chloride ion serving as an exogenous fourth ligand. Zinc binding was confirmed using anomalous difference maps and solution binding studies that revealed similar affinities of zinc for S100A15 and S100A7. Additionally, the predicted receptor-binding surface on S100A7 is substantially more basic in S100A15 without incurring structural rearrangement. Conclusions Here we demonstrate that S100A15 retains the ability to coordinate zinc through incorporation of an exogenous ligand resulting in a unique zinc-binding site among S100 proteins. The altered surface chemistry between S100A7 and S100A15 that localizes to the predicted receptor binding site is likely responsible for the differential recognition of distinct

  13. Temporal dynamics for soil aggregates determined using X-ray CT scanning

    DEFF Research Database (Denmark)

    Garbout, Amin; Munkholm, Lars Juhl; Hansen, Søren Baarsgaard

    2013-01-01

    aggregate properties such as volume, surface area and sphericity based on 3D images. We tested the methods on aggregates from different treatments and quantified changes over time. A total of 32 collections of aggregates, enclosed in mesocosms, were incubated in soil to follow the structural changes over...... time for different treatments. The aggregates had different origins (tillage and no-till), and the mesocosms were incubated in soil grown with and without plants. The aggregates were not segmented into single aggregates, but considered as an aggregate cluster. To describe the aggregate cluster shape...... of the aggregate clusters increased with time irrespective of tillage and plant treatments. The sphericity decreased with time. The structure model index (SMI) was not sensitive to effects of time and treatments. This means that with time the aggregate clusters became less round and more elongated, but they kept...

  14. Does thermophoresis reduce aggregate stability?

    Science.gov (United States)

    Sachs, Eyal; Sarah, Pariente

    2017-04-01

    Thermophoresis is mass flow driven by a thermal gradient. As a result of Seebeck effect and Soret effect, colloids can move from the hot to the cold region or vice versa, depending on the electrolyte composition and on the particle size. This migration of colloids can weaken aggregates. The effect of raindrop temperatures on runoff generation and erosion on clayey soil was investigated in sprinkling experiments with a laboratory rotating disk rain simulator. The experiments were applied to Rhodoxeralt (Terra Rossa) soil with two pre-prepared moisture contents: hygroscopic and field capacity. For each moisture content three rainfall temperatures were applied: 2, 20, and 35°C. Erosion was generally lower in the pre-wetted soil than in the dry soil (12.5 and 24.4 g m-2 per 40 mm of rain,respectively). Whereas there was no significant effect of raindrop temperature on the dry soil the soil that was pre-moistened to field capacity was affected by rainwater temperature: runoff and erosion were high when the temperature difference between rainfall and soil surface was high, sediment yields were 13.9, 5.2, and 18.3 g m-2 per 40 mm of rain, for rain temperature of 2, 20, and 35 °C, respectively. It is reasonable to conclude that thermophoresis caused by thermal gradients within the soil solution reduces the stability of aggregates and then increase the soil losses.

  15. Optimal Policies for Aggregate Recycling from Decommissioned Forest Roads

    Science.gov (United States)

    Thompson, Matthew; Sessions, John

    2008-08-01

    To mitigate the adverse environmental impact of forest roads, especially degradation of endangered salmonid habitat, many public and private land managers in the western United States are actively decommissioning roads where practical and affordable. Road decommissioning is associated with reduced long-term environmental impact. When decommissioning a road, it may be possible to recover some aggregate (crushed rock) from the road surface. Aggregate is used on many low volume forest roads to reduce wheel stresses transferred to the subgrade, reduce erosion, reduce maintenance costs, and improve driver comfort. Previous studies have demonstrated the potential for aggregate to be recovered and used elsewhere on the road network, at a reduced cost compared to purchasing aggregate from a quarry. This article investigates the potential for aggregate recycling to provide an economic incentive to decommission additional roads by reducing transport distance and aggregate procurement costs for other actively used roads. Decommissioning additional roads may, in turn, result in improved aquatic habitat. We present real-world examples of aggregate recycling and discuss the advantages of doing so. Further, we present mixed integer formulations to determine optimal levels of aggregate recycling under economic and environmental objectives. Tested on an example road network, incorporation of aggregate recycling demonstrates substantial cost-savings relative to a baseline scenario without recycling, increasing the likelihood of road decommissioning and reduced habitat degradation. We find that aggregate recycling can result in up to 24% in cost savings (economic objective) and up to 890% in additional length of roads decommissioned (environmental objective).

  16. Cell-surface trafficking and release of flt3 ligand from T lymphocytes is induced by common cytokine receptor gamma-chain signaling and inhibited by cyclosporin A.

    Science.gov (United States)

    Chklovskaia, E; Nissen, C; Landmann, L; Rahner, C; Pfister, O; Wodnar-Filipowicz, A

    2001-02-15

    The flt3 ligand (FL) is a growth and differentiation factor for primitive hematopoietic precursors, dendritic cells, and natural killer cells. Human T lymphocytes express FL constitutively, but the cytokine is retained intracellularly within the Golgi complex. FL is mobilized from the cytoplasmic stores and its serum levels are massively increased during the period of bone marrow aplasia after stem cell transplantation (SCT). Signals that trigger the release of FL by T cells remain unknown. This study shows that interleukin (IL)-2, IL-4, IL-7, and IL-15, acting through a common receptor gamma chain (gammac), but not cytokines interacting with other receptor families, are efficient inducers of cell surface expression of membrane-bound FL (mFL) and secretion of soluble FL (sFL) by human peripheral blood T lymphocytes. The gammac-mediated signaling up-regulated FL in a T-cell receptor-independent manner. IL-2 and IL-7 stimulated both FL messenger RNA (mRNA) expression and translocation of FL protein to the cell surface. Cyclosporin A (CsA) inhibited gammac-mediated trafficking of FL at the level of transition from the Golgi to the trans-Golgi network. Accordingly, serum levels of sFL and expression of mFL by T cells of CsA-treated recipients of stem cell allografts were reduced approximately 2-fold (P <.01) compared to patients receiving autologous grafts. The conclusion is that FL expression is controlled by gammac receptor signaling and that CsA interferes with FL release by T cells. The link between gammac-dependent T-cell activation and FL expression might be important for T-cell effector functions in graft acceptance and antitumor immunity after SCT.

  17. Aggregation of organic matter by pelagic tunicates

    Energy Technology Data Exchange (ETDEWEB)

    Pomeroy, L.R. (Univ. of Georgia, Athens); Deibel, D.

    1980-07-01

    Three genera of pelagic tunicates were fed concentrates of natural seston and an axenic diatom culture. Fresh and up to 4-day-old feces resemble flocculent organic aggregates containing populations of microorganisms, as described from highly productive parts of the ocean, and older feces resemble the nearly sterile flocculent aggregates which are ubiquitous in surface waters. Fresh feces consist of partially digested phytoplankton and other inclusions in an amorphous gelatinous matrix. After 18 to 36 h, a population of large bacteria develops in the matrix and in some of the remains of phytoplankton contained in the feces. From 48 to 96 h, protozoan populations arise which consume the bacteria and sometimes the remains of the phytoplankton in the feces. Thereafter only a sparse population of microorganisms remains, and the particles begin to fragment. Water samples taken in or below dense populations of salps and doliolids contained greater numbers of flocculent aggregates than did samples from adjacent stations.

  18. Aryl hydrocarbon receptor (AhR) inducers and estrogen receptor (ER) activities in surface sediments of Three Gorges Reservoir, China evaluated with in vitro cell bioassays.

    Science.gov (United States)

    Wang, Jingxian; Bovee, Toine F H; Bi, Yonghong; Bernhöft, Silke; Schramm, Karl-Werner

    2014-02-01

    Two types of biological tests were employed for monitoring the toxicological profile of sediment cores in the Three Gorges Reservoir (TGR), China. In the present study, sediments collected in June 2010 from TGR were analyzed for estrogen receptor (ER)- and aryl hydrocarbon receptor (AhR)-mediated activities. The estrogenic activity was assessed using a rapid yeast estrogen bioassay, based on the expression of a green fluorescent reporter protein. Weak anti-estrogenic activity was detected in sediments from an area close to the dam of the reservoir, and weak estrogenic activities ranging from 0.3 to 1 ng 17β-estradiol (E2) equivalents (EQ) g(-1) dry weight sediment (dw) were detected in sediments from the Wanzhou to Guojiaba areas. In the upstream areas Wanzhou and Wushan, sediments demonstrated additive effects in co-administration of 1 nM E2 in the yeast test system, while sediments from the downstream Badong and Guojiaba areas showed estrogenic activities which seemed to be more than additive (synergistic activity). There was an increasing tendency in estrogenic activity from upstream of TGR to downstream, while this tendency terminated and converted into anti-estrogenic activity in the area close to the dam. The AhR activity was detected employing rat hepatoma cell line (H4IIE). EROD activities were found homogenously distributed in sediments in TGR ranging from 200 to 311 pg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) EQ g(-1) dw for total AhR agonists and from 45 to 76 pg TCDD EQ g(-1) dw for more persistent AhR agonists. The known AhR agonists polycyclic aromatic hydrocarbon, polychlorinated biphenyl, and PCDD/F only explained up to 8 % of the more persistent AhR agonist activity in the samples, which suggests that unidentified AhR-active compounds represented a great proportion of the TCDD EQ in sediments from TGR. These findings of estrogenic potential and dioxin-like activity in TGR sediments provide possible weight-of-evidence of potential

  19. Concrete produced with recycled aggregates

    Directory of Open Access Journals (Sweden)

    J. J. L. Tenório

    Full Text Available This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW, which were divided into recycled sand (fine and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW. The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.

  20. ALTERED EXPRESSION OF SURFACE RECEPTORS AT EA.HY926 ENDOTHELIAL CELL LINE INDUCED WITH PLACENTAL SECRETORY FACTORS

    Directory of Open Access Journals (Sweden)

    O. I. Stepanova

    2012-01-01

    Full Text Available Abstract. Placental cell populations produce a great variety of angiogenic factors and cytokines than control angiogenesis in placenta. Functional regulation of endothelial cells proceeds via modulation of endothelial cell receptors for endogenous angiogenic and apoptotic signals. Endothelial phenotype alteration during normal pregnancy and in cases of preclampsia is not well understood. The goal of this investigation was to evaluate altered expression of angiogenic and cytokine receptors at EA.hy926 endothelial cells under the influence of placental tissue supernatants. Normal placental tissue supernatants from 1st and 3rd trimesters, and pre-eclamptic placental tissue supernatants (3rd trimester stimulated angiogenic and cytokine receptors expression by the cultured endothelial cells, as compared with their background expression. Tissue supernatants from placental samples of 3rd trimester caused a decreased expression of angiogenic and cytokine receptors by endothelial cells, thus reflecting maturation of placental vascular system at these terms. Supernatants from preeclamptic placental tissue induced an increase of CD119 expression, in comparison with normal placental supernatants from the 3rd trimester. This finding suggests that IFNγ may be a factor of endothelial activation in pre-eclampsia. The study was supported by grants ГК №02.740.11.0711, НШ-3594.2010.7., and МД-150.2011.7.

  1. Nanoscale organization of {beta}{sub 2}-adrenergic receptor-Venus fusion protein domains on the surface of mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Vobornik, Dusan; Rouleau, Yanouchka; Haley, Jennifer [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Bani-Yaghoub, Mahmud [Institute for Biological Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Taylor, Rod [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Johnston, Linda J., E-mail: Linda.Johnston@nrc-cnrc.gc.ca [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Pezacki, John Paul, E-mail: John.Pezacki@nrc-cnrc.gc.ca [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada)

    2009-04-24

    Adrenergic receptors are a key component of nanoscale multiprotein complexes that are responsible for controlling the beat rate in a mammalian heart. We demonstrate the ability of near-field scanning optical microscopy (NSOM) to visualize {beta}{sub 2}-adrenergic receptors ({beta}{sub 2}AR) fused to the GFP analogue Venus at the nanoscale on HEK293 cells. The expression of the {beta}{sub 2}AR-Venus fusion protein was tightly controlled using a tetracycline-induced promoter. Both the size and density of the observed nanoscale domains are dependent on the level of induction and thus the level of protein expression. At concentrations between 100 and 700 ng/ml of inducer doxycycline, the size of domains containing the {beta}{sub 2}AR-Venus fusion protein appears to remain roughly constant, but the number of domains per cell increase. At 700 ng/ml doxycycline the functional receptors are organized into domains with an average diameter of 150 nm with a density similar to that observed for the native protein on primary murine cells. By contrast, larger micron-sized domains of {beta}{sub 2}AR are observed in the membrane of the HEK293 cells that stably overexpress {beta}{sub 2}AR-GFP and {beta}{sub 2}AR-eYFP. We conclude that precise chemical control of gene expression is highly advantageous for the use {beta}{sub 2}AR-Venus fusion proteins as models for {beta}{sub 2}AR function. These observations are critical for designing future cell models and assays based on {beta}{sub 2}AR, since the receptor biology is consistent with a relatively low density of nanoscale receptor domains.

  2. Familial Aggregation of Insomnia.

    Science.gov (United States)

    Jarrin, Denise C; Morin, Charles M; Rochefort, Amélie; Ivers, Hans; Dauvilliers, Yves A; Savard, Josée; LeBlanc, Mélanie; Merette, Chantal

    2017-02-01

    There is little information about familial aggregation of insomnia; however, this type of information is important to (1) improve our understanding of insomnia risk factors and (2) to design more effective treatment and prevention programs. This study aimed to investigate evidence of familial aggregation of insomnia among first-degree relatives of probands with and without insomnia. Cases (n = 134) and controls (n = 145) enrolled in a larger epidemiological study were solicited to invite their first-degree relatives and spouses to complete a standardized sleep/insomnia survey. In total, 371 first-degree relatives (Mage = 51.9 years, SD = 18.0; 34.3% male) and 138 spouses (Mage = 55.5 years, SD = 12.2; 68.1% male) completed the survey assessing the nature, severity, and frequency of sleep disturbances. The dependent variable was insomnia in first-degree relatives and spouses. Familial aggregation was claimed if the risk of insomnia was significantly higher in the exposed (relatives of cases) compared to the unexposed cohort (relatives of controls). The risk of insomnia was also compared between spouses in the exposed (spouses of cases) and unexposed cohort (spouses of controls). The risk of insomnia in exposed and unexposed biological relatives was 18.6% and 10.4%, respectively, yielding a relative risk (RR) of 1.80 (p = .04) after controlling for age and sex. The risk of insomnia in exposed and unexposed spouses was 9.1% and 4.2%, respectively; however, corresponding RR of 2.13 (p = .28) did not differ significantly. Results demonstrate evidence of strong familial aggregation of insomnia. Additional research is warranted to further clarify and disentangle the relative contribution of genetic and environmental factors in insomnia.

  3. Concrete produced with recycled aggregates

    OpenAIRE

    Tenório,J. J. L.; Gomes,P. C. C.; Rodrigues,C. C.; Alencar,T. F. F. de

    2012-01-01

    This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC) for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW), which were d...

  4. Proteins aggregation and human diseases

    Science.gov (United States)

    Hu, Chin-Kun

    2015-04-01

    Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

  5. J-aggregation of cyanine dyes by self-assembly.

    Science.gov (United States)

    Steiger, Rolf; Pugin, Raphaël; Heier, Jakob

    2009-12-01

    The importance of highly ordered surfaces, containing adsorptive surface states, is discussed for J-aggregation by self-assembly. Such nucleating surfaces are nanometer-sized edges and corners of cubic AgBr microcrystals, or surface iodide-clusters located along edges and corners of AgBr:I microcrystals. Of particular interest are dendrimers, monoatomic steps on terraced silver halide microcrystals and fullerene derivatives as nucleating surfaces. Molecular organisation into J-aggregates by self-assembly was realized using aprotic, apolar solvents for fullerenes, and polar solvents for dendrimers and monoatomic surface steps. By using dendrimers as nucleating agents in mesopores of metal oxide nanoparticle coatings, size-controlled and stable J-aggregates with high optical densities and strong fluorescence were obtained reproducibly. Such films may be useful for sensors, opto-electronics, lighting and photovoltaics.

  6. Substance P Increases Cell-Surface Expression of CD74 (Receptor for Macrophage Migration Inhibitory Factor: In Vivo Biotinylation of Urothelial Cell-Surface Proteins

    Directory of Open Access Journals (Sweden)

    Katherine L. Meyer-Siegler

    2009-01-01

    N-hydroxysulfosuccinimide biotin ester-labeled surface urothelial proteins in rats treated either with saline or substance P (SP, 40 μg/kg. The bladder was examined by histology and confocal microscopy. Biotinylated proteins were purified by avidin agarose, immunoprecipitated with anti-MIF or anti-CD74 antibodies, and detected with strepavidin-HRP. Only superficial urothelial cells were biotinylated. These cells contained a biotinylated MIF/CD74 cell-surface complex that was increased in SP-treated animals. SP treatment increased MIF and CD74 mRNA in urothelial cells. Our data indicate that intraluminal MIF, released from urothelial cells as a consequence of SP treatment, interacts with urothelial cell-surface CD74. These results document that our previously described MIF-CD74 interaction occurs at the urothelial cell surface.

  7. Prostaglandin E2 Receptor Expression by Osteoblasts is Modulated by Implant Surface Roughness and Prostaglandin E2

    Science.gov (United States)

    2006-05-01

    CAPT CAMPBELL CASEY M 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION UNIVERSITY OF TEXAS HSC AT SAN ANTONIO REPORT...Analysis, 4. Verlag Chemica , Weinheim, 65-92. Breyer RM, Bagdassarian CK, Myers SA, Breyer MD (2001): Prostanoid receptors: subtypes and signaling...prostaglandin E2 in organ culture. Prostaglandins 8:377-385. Sabbieti MG, Marchetti L, Abreu C, Montero A, Hand AR, Raisz LG, Hurley MM (1999

  8. Binding of the urokinase-type plasminogen activator to its cell surface receptor is inhibited by low doses of suramin

    DEFF Research Database (Denmark)

    Behrendt, N; Rønne, E; Danø, K

    1993-01-01

    The multipotent drug suramin, which is currently being studied as an anticancer agent, was found to inhibit the interaction between the urokinase-type plasminogen activator (u-PA) and its cellular receptor. 50% inhibition of binding was obtained with a suramin concentration between 30 and 60...... to the anti-invasive properties of suramin by destroying the cellular potential for localized plasminogen activation and proteolytic matrix degradation....

  9. Different Use of Cell Surface Glycosaminoglycans As Adherence Receptors to Corneal Cells by Gram Positive and Gram Negative Pathogens

    Science.gov (United States)

    García, Beatriz; Merayo-Lloves, Jesús; Rodríguez, David; Alcalde, Ignacio; García-Suárez, Olivia; Alfonso, José F.; Baamonde, Begoña; Fernández-Vega, Andrés; Vazquez, Fernando; Quirós, Luis M.

    2016-01-01

    The epithelium of the cornea is continuously exposed to pathogens, and adhesion to epithelial cells is regarded as an essential first step in bacterial pathogenesis. In this article, the involvement of glycosaminoglycans in the adhesion of various pathogenic bacteria to corneal epithelial cells is analyzed. All microorganisms use glycosaminoglycans as receptors, but arranged in different patterns depending on the Gram-type of the bacterium. The heparan sulfate chains of syndecans are the main receptors, though other molecular species also seem to be involved, particularly in Gram-negative bacteria. Adherence is inhibited differentially by peptides, including heparin binding sequences, indicating the participation of various groups of Gram-positive, and -negative adhesins. The length of the saccharides produces a major effect, and low molecular weight chains inhibit the binding of Gram-negative microorganisms but increase the adherence of Gram-positives. Pathogen adhesion appears to occur preferentially through sulfated domains, and is very dependent on N- and 6-O-sulfation of the glucosamine residue and, to a lesser extent, 2-O sulfation of uronic acid. These data show the differential use of corneal receptors, which could facilitate the development of new anti-infective strategies. PMID:27965938

  10. Dynamics of fire ant aggregations

    Science.gov (United States)

    Tennenbaum, Michael; Hu, David; Fernandez-Nieves, Alberto

    Fire ant aggregations are an inherently active system. Each ant harvests its own energy and can convert it into motion. The motion of individual ants contributes non-trivially to the bulk material properties of the aggregation. We have measured some of these properties using plate-plate rheology, where the response to an applied external force or deformation is measured. In this talk, we will present data pertaining to the aggregation behavior in the absence of any external force. We quantify the aggregation dynamics by monitoring the rotation of the top plate and by measuring the normal force. We then compare the results with visualizations of 2D aggregations.

  11. Influence of aggregate gradation on hma mixes stability

    Directory of Open Access Journals (Sweden)

    Kalaitzaki Elvira

    2015-12-01

    Full Text Available The load transfer capacity of pavements is to a great extend influenced by aggregates. About 85% of the total volume of hot mix asphalt (HMA mixtures consists of aggregates; thus, they are greatly influenced by aggregate properties like angularity (shape, roughness (texture, and gradation. Aggregate gradation controls the structure of voids. Current specifications for aggregate properties in HMA pavements require the aggregate blend to fall within a specified range of gradation values. Although the abovementioned requirement has ensured the construction of high quality HMA pavements, the properties are largely empirical and they are not based on performance-related tests. Marshall Stability is in principle the resistance to plastic flow of cylindrical specimens of a bituminous mixture loaded on the lateral surface. It is the load carrying capacity of the mix at 60oC. Aggregates with different gradations from the broader area of Xanthi, Northern Greece, have been used to prepare specimens for stability testing of hot asphalt mixtures in the laboratory. The research focused on the evaluation of the influence of aggregates in the overall stability characteristics of the mixtures. The maximum stability value has been obtained with an open-graded mixture having 5% asphalt and aggregate size 2.36 mm. However, the stability of the dense graded mixture is higher than this maximum value.

  12. A surface membrane protein of Entamoeba histolytica functions as a receptor for human chemokine IL-8: its role in the attraction of trophozoites to inflammation sites.

    Science.gov (United States)

    Diaz-Valencia, J Daniel; Pérez-Yépez, Eloy Andrés; Ayala-Sumuano, Jorge Tonatiuh; Franco, Elizabeth; Meza, Isaura

    2015-12-01

    Entamoeba histolytica trophozoites respond to the presence of IL-8, moving by chemotaxis towards the source of the chemokine. IL-8 binds to the trophozoite membrane and triggers a response that activates signaling pathways that in turn regulate actin/myosin cytoskeleton organisation to initiate migration towards the chemokine, suggesting the presence of a receptor for IL-8 in the parasite. Antibodies directed to the human IL-8 receptor (CXCR1) specifically recognised a 29 kDa protein in trophozoite membrane fractions. The same protein was immunoprecipitated by this antibody from total amebic extracts. Peptide analysis of the immunoprecipitated protein revealed a sequence with high homology to a previously identified amebic outer membrane peroxiredoxin and a motif within the third loop of human CXCR1, which is an important site for IL-8 binding and activation of signaling processes. Immunodetection assays demonstrated that the anti-human CXCR1 antibody binds to the 29 kDa protein in a different but close site to where IL-8 binds to the trophozoite surface membrane, suggesting that human and amebic receptors for this chemokine share common epitopes. In the context of the human intestinal environment, a receptor for IL-8 could be a great advantage for E. histolytica trophozoite survival, as they could reach an inflammatory milieu containing abundant nutrients. In addition, it has been suggested that the high content of accessible thiol groups of the protein and its peroxidase activity could provide protection in the oxygen rich milieu of colonic lesions, allowing trophozoite invasion of other tissues and escape from the host immune response. Copyright © 2015 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  13. Ligands Binding to Cell Surface Ganglioside GD2 Cause Src-Dependent Activation of N-Methyl-D-Aspartate Receptor Signaling and Changes in Cellular Morphology.

    Directory of Open Access Journals (Sweden)

    Wenyong Tong

    Full Text Available Ganglioside GD2 is a plasma membrane glycosphinogolipid. In healthy adults it is expressed at low levels, but it is over-expressed in many cancers. For cancer therapy, GD2 is targeted with anti-GD2 monoclonal antibodies (mAbs, and one adverse side effect is severe visceral pain. Pain is not neuropathic, cannot be blocked with morphine, and stops on discontinuation of mAb therapy. Here, we provide evidence that ligand binding to cell surface GD2 induces rapid and transient activation of Src-family kinases, followed by Src-dependent phosphorylation of NMDA-receptor NR2B subunits selectively, activation of Ca++ fluxes, production of cAMP, and changes in cellular morphology. These GD2-ligand activated signals differ in kinetics and in pharmacology from activation of the same signals in the same cells by BDNF, the growth factor agonist of the TrkB receptor, suggesting biological specificity. Hence, cell surface GD2 regulates pathways that can be associated with neoplasia and with morphine-intractable pain; and this can explain why expression of GD2 correlates with these two pathologies.

  14. An integrated model for assessing the risk of TCE groundwater contamination to human receptors and surface water ecosystems

    DEFF Research Database (Denmark)

    McKnight, Ursula S.; Funder, S.G.; Rasmussen, J.J.

    2010-01-01

    The practical implementation of the European Water Framework Directive has resulted in an increased focus on the hyporheic zone. In this paper, an integrated model was developed for evaluating the impact of point sources in groundwater on human health and surface water ecosystems. This was accomp......The practical implementation of the European Water Framework Directive has resulted in an increased focus on the hyporheic zone. In this paper, an integrated model was developed for evaluating the impact of point sources in groundwater on human health and surface water ecosystems...... will not be depleted for many decades, however measured and predicted TCE concentrations in surface water were found to be below human health risk management targets. Volatilization rapidly attenuates TCE concentrations in surface water. Thus, only a 300 m stream reach fails to meet surface water quality criteria...

  15. Distinguishing aggregate formation and aggregate clearance using cell-based assays

    NARCIS (Netherlands)

    Eenjes, Evelien; Dragich, Joanna M.; Kampinga, Harm H.; Yamamoto, Ai

    2016-01-01

    The accumulation of ubiquitylated proteinaceous inclusions represents a complex process, reflecting the disequilibrium between aggregate formation and aggregate clearance. Although decreasing aggregate formation or augmenting aggregate clearance will ultimately lead to a diminished aggregate burden,

  16. Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties

    OpenAIRE

    Neeraj Jain; Mridul Garg; A. K. Minocha

    2015-01-01

    Present investigations deal with the development of green concrete (M 30 grade) using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100%) with recycled coarse aggregate on various mechanical ...

  17. Distinct domains of the CD3-gamma chain are involved in surface expression and function of the T cell antigen receptor

    DEFF Research Database (Denmark)

    Wegener, A M; Hou, X; Dietrich, J

    1995-01-01

    The T cell antigen receptor (TcR) is a multisubunit complex that consists of at least six different polypeptides. We have recently demonstrated that the CD3-delta subunit cannot substitute for the CD3-gamma subunit in TcR cell surface expression, in spite of significant amino acid homology between...... these two subunits. To identify CD3-gamma-specific domains that are required for assembly of the complete TcR and for surface expression and function of the TcR, chimeric CD3-gamma/CD3-delta molecules were constructed and expressed in T cells devoid of endogenous CD3-gamma. Substitution of the extracellular...... domain of CD3-gamma with that of CD3-delta did not allow cell surface expression of the TcR. In contrast, substitution of the transmembrane and/or the intracellular domains of CD3-gamma with those of CD3-delta did allow TcR cell surface expression. These results conclusively demonstrate...

  18. Neutrophil surface adhesion molecule and toll like receptor dynamics in crossbred cows suffering from Staphylococcus aureus subclinical and clinical mastitis

    Directory of Open Access Journals (Sweden)

    Dilip Kumar Swain

    2016-06-01

    Conclusion: Host elicits stage specific expression of surface adhesion molecules and TLR2 and TLR4 as dynamic host innate immune response against Staphylococcal mastitis. [J Adv Vet Anim Res 2016; 3(2.000: 99-105

  19. Histamine H1 and H4 receptor expression on the ocular surface of patients with chronic allergic conjunctival diseases.

    Science.gov (United States)

    Inada, Noriko; Shoji, Jun; Shiraki, Yukiko; Aso, Hiroshi; Yamagami, Satoru

    2017-10-01

    This study investigated the histamine H1 and H4 receptors mRNA (H1R and H4R, respectively) expression on the ocular surface of patients with chronic forms of allergic conjunctival diseases to determine whether they can serve as biomarkers for allergic inflammation in the conjunctiva. We examined 19 patients with vernal or atopic keratoconjunctivitis (AKC/VKC group) and 15 healthy volunteers (control group). The AKC/VKC group was divided into active and stable stage subgroups. Specimens were obtained from the upper tarsal conjunctiva of each participant using a modified impression cytology method. H1R, H4R, and eotaxin-1, -2, and -3 mRNA (eotaxin-1, eotaxin-2, eotaxin-3, respectively) expression was determined by real-time RT-PCR. Immunohistochemical analysis for eosinophil cationic protein (ECP), eosinophil major basic protein (MBP), eotaxin-2, and histamine H4 receptor (H4R) were performed using conjunctival smears. The number of H4R-positive patients was higher in the active than the stable stage subgroup and control group, whereas no difference was observed for H1R. H1R levels were higher in the active than in the stable stage subgroup, while those of H4R were higher in the active stage subgroup than in the control group. H1R and H4R levels were correlated with eotaxin-2 level. In immunohistochemical analysis, H4R revealed their expression on eosinophils in conjunctival smears of patients with AKC/VKC. H4R is useful as biomarkers of allergic inflammation on ocular surfaces. Most notably, H4R expressed on eosinophils is useful as a biomarker of eosinophilic inflammation of the ocular surface. Copyright © 2017 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

  20. Six host range variants of the xenotropic/polytropic gammaretroviruses define determinants for entry in the XPR1 cell surface receptor

    Directory of Open Access Journals (Sweden)

    Kozak Christine A

    2009-10-01

    Full Text Available Abstract Background The evolutionary interactions between retroviruses and their receptors result in adaptive selection of restriction variants that can allow natural populations to evade retrovirus infection. The mouse xenotropic/polytropic (X/PMV gammaretroviruses rely on the XPR1 cell surface receptor for entry into host cells, and polymorphic variants of this receptor have been identified in different rodent species. Results We screened a panel of X/PMVs for infectivity on rodent cells carrying 6 different XPR1 receptor variants. The X/PMVs included 5 well-characterized laboratory and wild mouse virus isolates as well as a novel cytopathic XMV-related virus, termed Cz524, isolated from an Eastern European wild mouse-derived strain, and XMRV, a xenotropic-like virus isolated from human prostate cancer. The 7 viruses define 6 distinct tropisms. Cz524 and another wild mouse isolate, CasE#1, have unique species tropisms. Among the PMVs, one Friend isolate is restricted by rat cells. Among the XMVs, two isolates, XMRV and AKR6, differ from other XMVs in their PMV-like restriction in hamster cells. We generated a set of Xpr1 mutants and chimeras, and identified critical amino acids in two extracellular loops (ECLs that mediate entry of these different viruses, including 3 residues in ECL3 that are involved in PMV entry (E500, T507, and V508 and can also influence infectivity by AKR6 and Cz524. Conclusion We used a set of natural variants and mutants of Xpr1 to define 6 distinct host range variants among naturally occurring X/PMVs (2 XMV variants, 2 PMVs, 2 different wild mouse variants. We identified critical amino acids in XPR1 that mediate entry of these viruses. These gammaretroviruses and their XPR1 receptor are thus highly functionally polymorphic, a consequence of the evolutionary pressures that favor both host resistance and virus escape mutants. This variation accounts for multiple naturally occurring virus resistance phenotypes and

  1. Exploratory observations of marine aggregates at sub-euphotic depths

    Science.gov (United States)

    Silver, Mary W.; Coale, Susan L.; Pilskaln, Cynthia H.; Chavez, Francisco P.

    1998-08-01

    Aggregates >0.25 mm were collected over a 4-year period below the euphotic zone at depths between 40-251 m and at a 400-1000 m deep station in the Monterey Submarine Canyon system using a remotely operated vehicle (ROV). The aggregates were sized and characterized to determine their origins and possible association with local production cycles at a station regularly monitored by the Monterey Bay Aquarium Research Institute's (MBARI's) ocean monitoring program. We present a first-time inventory of particle types with their size distribution for Monterey Bay. Phytoplankton-containing aggregates number about half of the total aggregates in the upper, 40-251 m layer, but decline to 5% at 400 m, possibly due to offshore transport of sinking material, input of resuspended aggregates at depth, and/or intense biological recycling of aggregates in the midwater. In the upper layer, only the abundance of the phytoplankton containing aggregates was weakly correlated with local phytoplankton abundance as measured by in situ fluorescence on that day at a near-by mooring: correlations did not exist for total numbers of aggregates. Instead, aggregates were mostly of detrital origin, with organic matter of unrecognizable origin and sometimes with conspicuous lithogenic material. Particles of fecal origin were third in abundance, and their numbers are relatively low (25 l -1) compared with aggregates, likely because of their higher sinking rates. We suggest that many of the sub-euphotic aggregates in this system may be derived from additional sources or events not directly tied to production cycles. Because particles such as these are likely responsible for the observed mass flux at this site (see Pilskaln et al., 1998), the concept of a simple, surface-driven "biological pump" may not be applicable on short-time scales in predicting material flux in dynamic continental margin systems.

  2. Prion protein dynamics before aggregation

    National Research Council Canada - National Science Library

    Srivastava, Kinshuk Raj; Lapidusa, Lisa J

    2017-01-01

      Prion diseases, like Alzheimer's disease and Parkinson disease, are rapidly progressive neurodegenerative disorders caused by misfolding followed by aggregation and accumulation of protein deposits in neuronal cells...

  3. Floating ice-algal aggregates below melting arctic sea ice.

    Directory of Open Access Journals (Sweden)

    Philipp Assmy

    Full Text Available During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year.

  4. Uric acid increases erythrocyte aggregation: Implications for cardiovascular disease.

    Science.gov (United States)

    Sloop, Gregory D; Bialczak, Jessica K; Weidman, Joseph J; St Cyr, J A

    2016-10-05

    Uric acid may be a risk factor for atherosclerotic cardiovascular disease, although the data conflict and the mechanism by which it may cause cardiovascular disease is uncertain. This study was performed to test the hypothesis that uric acid, an anion at physiologic pH, can cause erythrocyte aggregation, which itself is associated with cardiovascular disease. Normal erythrocytes and erythrocytes with a positive direct antiglobulin test for surface IgG were incubated for 15 minutes in 14.8 mg/dL uric acid. Erythrocytes without added uric acid were used as controls. Erythrocytes were then examined microscopically for aggregation. Aggregates of up to 30 erythrocytes were noted when normal erythrocytes were incubated in uric acid. Larger aggregates were noted when erythrocytes with surface IgG were incubated in uric acid. Aggregation was negligible in controls. These data show that uric acid causes erythrocyte aggregation. The most likely mechanism is decreased erythrocyte zeta potential. Erythrocyte aggregates will increase blood viscosity at low shear rates and increase the risk of atherothrombosis. In this manner, hyperuricemia and decreased zeta potential may be risk factors for atherosclerotic cardiovascular disease.

  5. 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.

  6. Surface ozone at the Devils Postpile National Monument receptor site during low and high wildland fire years

    Science.gov (United States)

    Andrzej Bytnerowicz; Joel D. Burley; Ricardo Cisneros; Haiganoush K. Preisler; Susan Schilling; Donald Schweizer; John Ray; Deanna Dulen; Christopher Beck; Bianca Auble

    2013-01-01

    Surface ozone (O3) was measured at the Devils Postpile National Monument (DEPO), eastern Sierra Nevada Mountains, California, during the 2007 (low-fire) and 2008 (high-fire) summer seasons. While mean and median values of O3 concentrations for the 2007 and 2008 summer seasons were similar, maximum O3...

  7. Influence of treated recycled concrete aggregate on concrete properties

    OpenAIRE

    Galindo, Anna; Etxeberria Larrañaga, Miren

    2017-01-01

    The amount and the quality of the old cement mortar attached to the aggregates influence the quality of the recycled concrete aggregate (RCA) produced. The characteristics of RCA adversely affect the physical, mechanical and durability properties of concretes. Due to these adverse effects, it is necessary to improve the RCA properties, not only changing their surface but also their internal microstructure. The main objective of this research work was to analyse the influence of chemically tre...

  8. Formation of fractal aggregates during green synthesis of silver nanoparticles

    Science.gov (United States)

    Singh, Manjeet; Sinha, I.; Singh, A. K.; Mandal, R. K.

    2011-01-01

    The aggregation behavior of silver nanoparticles (AgNPs) prepared by a green synthesis procedure using starch as the stabilizer was studied by the small angle X-ray scattering (SAXS) technique. The protecting ability of starch was affected by the presence of NaOH leading to different aggregation behaviors. In all the samples, mass as well as surface fractal regimes were observed. Assuming spherical form, the radii of nanoparticles were in the range of 11-17 nm.

  9. Microbial properties of soil aggregates created by earthworms and other factors: spherical and prismatic soil aggregates from unreclaimed post-mining sites

    Energy Technology Data Exchange (ETDEWEB)

    Frouz, J.; Kristufek, V.; Liveckova, M.; van Loo, D.; Jacobs, P.; Van Hoorebeke, L. [Charles University of Prague, Prague (Czech Republic). Inst. of Environmental Studies

    2011-01-15

    Soil aggregates between 2 and 5 mm from 35- and 45-year-old unreclaimed post-mining sites near Sokolov (Czech Republic) were divided into two groups: spherical and prismatic. X-ray tomography indicated that prismatic aggregates consisted of fragments of claystone bonded together by amorphous clay and roots while spherical aggregates consisted of a clay matrix and organic fragments of various sizes. Prismatic aggregates were presumed to be formed by plant roots and physical processes during weathering of Tertiary mudstone, while earthworms were presumed to contribute to the formation of spherical aggregates. The effects of drying and rewetting and glucose addition on microbial respiration, microbial biomass, and counts of bacteria in these aggregates were determined. Spherical aggregates contained a greater percentage of C and N and a higher C-to-N ratio than prismatic ones. The C content of the particulate organic matter was also higher in the spherical than in the prismatic aggregates. Although spherical aggregates had a higher microbial respiration and biomass, the growth of microbial biomass in spherical aggregates was negatively correlated with initial microbial biomass, indicating competition between bacteria. Specific respiration was negatively correlated with microbial biomass. Direct counts of bacteria were higher in spherical than in prismatic aggregates. Bacterial numbers were more stable in the center than in the surface layers of the aggregates. Transmission electron microscopy indicated that bacteria often occurred as individual cells in prismatic aggregates but as small clusters of cells in spherical aggregates. Ratios of colony forming units (cultivatable bacteria) to direct counts were higher in spherical than in prismatic aggregates. Spherical aggregates also contained faster growing bacteria.

  10. Interfacial adsorption and aggregation of amphiphilic proteins

    Science.gov (United States)

    Cheung, David

    2012-02-01

    The adsorption and aggregation on liquid interfaces of proteins is important in many biological contexts, such as the formation of aerial structures, immune response, and catalysis. Likewise the adsorption of proteins onto interfaces has applications in food technology, drug delivery, and in personal care products. As such there has been much interest in the study of a wide range of biomolecules at liquid interfaces. One class of proteins that has attracted particular attention are hydrophobins, small, fungal proteins with a distinct, amphiphilic surface structure. This makes these proteins highly surface active and they recently attracted much interest. In order to understand their potential applications a microscopic description of their interfacial and self-assembly is necessary and molecular simulation provides a powerful tool for providing this. In this presentation I will describe some recent work using coarse-grained molecular dynamics simulations to study the interfacial and aggregation behaviour of hydrophobins. Specifically this will present the calculation of their adsorption strength at oil-water and air-water interfaces, investigate the stability of hydrophobin aggregates in solution and their interaction with surfactants.

  11. Apoplastic venom allergen-like proteins of cyst nematodes modulate the activation of basal plant innate immunity by cell surface receptors.

    Directory of Open Access Journals (Sweden)

    Jose L Lozano-Torres

    2014-12-01

    Full Text Available Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes

  12. Characterization of Nanoparticle Aggregation in Biologically Relevant Fluids

    Science.gov (United States)

    McEnnis, Kathleen; Lahann, Joerg

    Nanoparticles (NPs) are often studied as drug delivery vehicles, but little is known about their behavior in blood once injected into animal models. If the NPs aggregate in blood, they will be shunted to the liver or spleen instead of reaching the intended target. The use of animals for these experiments is costly and raises ethical questions. Typically dynamic light scattering (DLS) is used to analyze aggregation behavior, but DLS cannot be used because the components of blood also scatter light. As an alternative, a method of analyzing NPs in biologically relevant fluids such as blood plasma has been developed using nanoparticle tracking analysis (NTA) with fluorescent filters. In this work, NTA was used to analyze the aggregation behavior of fluorescent polystyrene NPs with different surface modifications in blood plasma. It was expected that different surface chemistries on the particles will change the aggregation behavior. The effect of the surface modifications was investigated by quantifying the percentage of NPs in aggregates after addition to blood plasma. The use of this characterization method will allow for better understanding of particle behavior in the body, and potential problems, specifically aggregation, can be addressed before investing in in vivo studies.

  13. Copper-triggered aggregation of ubiquitin.

    Directory of Open Access Journals (Sweden)

    Fabio Arnesano

    Full Text Available Neurodegenerative disorders share common features comprising aggregation of misfolded proteins, failure of the ubiquitin-proteasome system, and increased levels of metal ions in the brain. Protein aggregates within affected cells often contain ubiquitin, however no report has focused on the aggregation propensity of this protein. Recently it was shown that copper, differently from zinc, nickel, aluminum, or cadmium, compromises ubiquitin stability and binds to the N-terminus with 0.1 micromolar affinity. This paper addresses the role of copper upon ubiquitin aggregation. In water, incubation with Cu(II leads to formation of spherical particles that can progress from dimers to larger conglomerates. These spherical oligomers are SDS-resistant and are destroyed upon Cu(II chelation or reduction to Cu(I. In water/trifluoroethanol (80:20, v/v, a mimic of the local decrease in dielectric constant experienced in proximity to a membrane surface, ubiquitin incubation with Cu(II causes time-dependent changes in circular dichroism and Fourier-transform infrared spectra, indicative of increasing beta-sheet content. Analysis by atomic force and transmission electron microscopy reveals, in the given order, formation of spherical particles consistent with the size of early oligomers detected by gel electrophoresis, clustering of these particles in straight and curved chains, formation of ring structures, growth of trigonal branches from the rings, coalescence of the trigonal branched structures in a network. Notably, none of these ubiquitin aggregates was positive to tests for amyloid and Cu(II chelation or reduction produced aggregate disassembly. The early formed Cu(II-stabilized spherical oligomers, when reconstituted in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC liposomes and in POPC planar bilayers, form annular and pore-like structures, respectively, which are common to several neurodegenerative disorders including Parkinson's, Alzheimer

  14. Dye-sensitized solar cell employing zinc oxide aggregates grown in the presence of lithium

    Science.gov (United States)

    Zhang, Qifeng; Cao, Guozhong

    2013-10-15

    Provided are a novel ZnO dye-sensitized solar cell and method of fabricating the same. In one embodiment, deliberately added lithium ions are used to mediate the growth of ZnO aggregates. The use of lithium provides ZnO aggregates that have advantageous microstructure, morphology, crystallinity, and operational characteristics. Employing lithium during aggregate synthesis results in a polydisperse collection of ZnO aggregates favorable for porosity and light scattering. The resulting nanocrystallites forming the aggregates have improved crystallinity and more favorable facets for dye molecule absorption. The lithium synthesis improves the surface stability of ZnO in acidic dyes. The procedures developed and disclosed herein also help ensure the formation of an aggregate film that has a high homogeneity of thickness, a high packing density, a high specific surface area, and good electrical contact between the film and the fluorine-doped tin oxide electrode and among the aggregate particles.

  15. An integrated model for assessing the risk of TCE groundwater contamination to human receptors and surface water ecosystems

    DEFF Research Database (Denmark)

    McKnight, Ursula S.; Funder, S.G.; Rasmussen, J.J.

    2010-01-01

    . An ecological risk assessment found that the TCE contamination did not impact the stream ecosystem. Uncertainty assessment revealed hydraulic conductivity to be the most important site-specific parameter. These results indicate that contaminant plumes with μgL-1 concentrations of TCE entering surface water......The practical implementation of the European Water Framework Directive has resulted in an increased focus on the hyporheic zone. In this paper, an integrated model was developed for evaluating the impact of point sources in groundwater on human health and surface water ecosystems....... This was accomplished by coupling the system dynamics-based decision support system CARO-PLUS to the aquatic ecosystem model AQUATOX using an analytical volatilization model for the stream. The model was applied to a case study where a TCE contaminated groundwater plume is discharging to a stream. The TCE source...

  16. Exciton dynamics in molecular aggregates

    NARCIS (Netherlands)

    Augulis, R.; Pugžlys, A.; Loosdrecht, P.H.M. van; Pugzlys, A

    2006-01-01

    The fundamental aspects of exciton dynamics in double-wall cylindrical aggregates of cyanine dyes are studied by means of frequency resolved femtosecond pump-probe spectroscopy. The collective excitations of the aggregates, resulting from intermolecular dipole-dipole interactions have the

  17. Collective Rationality in Graph Aggregation

    NARCIS (Netherlands)

    Endriss, U.; Grandi, U.; Schaub, T.; Friedrich, G.; O'Sullivan, B.

    2014-01-01

    Suppose a number of agents each provide us with a directed graph over a common set of vertices. Graph aggregation is the problem of computing a single “collective” graph that best represents the information inherent in this profile of individual graphs. We consider this aggregation problem from the

  18. Aggregating energy flexibilities under constraints

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Pedersen, Torben Bach; Abello, Alberto

    2016-01-01

    The flexibility of individual energy prosumers (producers and/or consumers) has drawn a lot of attention in recent years. Aggregation of such flexibilities provides prosumers with the opportunity to directly participate in the energy market and at the same time reduces the complexity of scheduling...... the energy units. However, aggregated flexibility should support normal grid operation. In this paper, we build on the flex-offer (FO) concept to model the inherent flexibility of a prosumer (e.g., a single flexible consumption device such as a clothes washer). An FO captures flexibility in both time...... and amount dimensions. We define the problem of aggregating FOs taking into account grid power constraints. We also propose two constraint-based aggregation techniques that efficiently aggregate FOs while retaining flexibility. We show through a comprehensive evaluation that our techniques, in contrast...

  19. Soluble forms of tumor necrosis factor receptors (TNF-Rs). The cDNA for the type I TNF-R, cloned using amino acid sequence data of its soluble form, encodes both the cell surface and a soluble form of the receptor

    DEFF Research Database (Denmark)

    Nophar, Y; Kemper, O; Brakebusch, C

    1990-01-01

    found to have effects characteristic of TNF, including stimulating phosphorylation of specific cellular proteins. Oligonucleotide probes designed on the basis of the NH2-terminal amino acid sequence of TBPI were used to clone the cDNA for the structurally related cell surface type 1 TNF-R. It is notable...... of structure, did not suggest any identity between this protein and the extracellular domain of the type I TNF-R. CHO cells transfected with type I TNF-R cDNA produced both cell surface and soluble forms of the receptor. The receptor produced by CHO cells was recognized by several monoclonal antibodies against...... in the extracellular domains of the nerve growth factor receptor and the B lymphocytes surface antigen CDw40. The amino acid composition and size of the extracellular domain of the type I TNF-R closely resemble those of TBPI. The COOH-terminal amino acid sequence of the four cysteine rich repeats within...

  20. Photoisomerization of azobenzene derivatives confined in gold nanoparticle aggregates.

    Science.gov (United States)

    Yoon, Jun Hee; Yoon, Sangwoon

    2011-07-28

    Photoisomerization is an important reaction that confers photoresponsive functionality on nanoparticles. Although photoisomerization of molecules forming self-assembled monolayers on two-dimensional surfaces or three-dimensional clusters has been studied, a detailed picture of interactions of molecules undergoing isomerization with nanoparticles is not available. In this paper, we report on the photoisomerization of azobenzene derivatives spatially confined in gold nanoparticle (AuNP) aggregates. AuNP aggregates allow us to simultaneously probe the structural changes of molecules via surface-enhanced Raman spectroscopy (SERS) and the accompanying changes in interparticle interactions via surface plasmon couplings. AuNP aggregates are formed by the adsorption of synthesized azobenzene-derivatized sulfides (Az) onto the surfaces of AuNPs. The photoisomerization of the adsorbed Az from trans to cis by excitation at 365 nm causes the AuNPs to move close to each other in the aggregates, leading to a redshift of the surface plasmon coupling band in the UV-vis spectra and a concomitant rise in SERS intensity. SERS spectra reveal that the vibrational modes containing the N=N stretching character redshift upon irradiation, suggesting that the N=N bond is significantly weakened when Az is in the cis form in the AuNP aggregates. The weakening of the N=N bond is attributed to the interaction of the N=N bond, which is more exposed to the outside in the cis conformation, with the nearby AuNPs that have come closer by the isomerization of adsorbed Az. We find that backisomerization from cis to trans occurs much faster in the AuNP aggregates (k = 1.9 × 10(-2) min(-1)) than in solution (k = 1.3 × 10(-3) min(-1)) because of the reduced N=N bond order of cis-Az in the aggregates. This journal is © the Owner Societies 2011

  1. Dabigatran reduces thrombin-induced platelet aggregation and activation in a dose-dependent manner

    DEFF Research Database (Denmark)

    Vinholt, Pernille Just; Nielsen, Christian; Söderström, Anna Cecilia

    2017-01-01

    Dabigatran is an oral anticoagulant and a reversible inhibitor of thrombin. Further, dabigatran might affect platelet function through a direct effect on platelet thrombin receptors. The aim was to investigate the effect of dabigatran on platelet activation and platelet aggregation. Healthy donor...... platelet activation and platelet thrombin receptor expression (SPAN-12 and WEDE-15 expression). Agonists were thrombin, thrombin receptor-activating peptide, protease-activated receptor-4 agonist, collagen, collagen-related peptide, arachidonic acid, and adenosine diphosphate. All concentrations...... of dabigatran fully inhibited platelet aggregation for thrombin up to 2 IU/mL, while dabigatran did not affect platelet aggregation by other agonists. Platelet activation (percentage of platelets positive for activated GPIIb/IIIa, CD63, P-selectin) was reduced after thrombin stimulation in samples...

  2. Epidermal growth factor receptor mutation type III transfected into a small cell lung cancer cell line is predominantly localized at the cell surface and enhances the malignant phenotype.

    Science.gov (United States)

    Damstrup, Lars; Wandahl Pedersen, Mikkel; Bastholm, Lone; Elling, Folmer; Skovgaard Poulsen, Hans

    2002-01-01

    In the present study we transfected the epidermal growth factor receptor (EGFR)-negative small cell lung cancer cell line, GLC3, with the type III EGFR mutation (EGFRvIII). The EGFRvIII protein could be detected by Western blot analysis as a 145-kDa protein, which by immunohistochemistry appeared to be localized at the cell surface. Ultrastructurally EGFRvIII was expressed mainly at the cell surface with clusters at cell-cell contacts. In the in vitro invasion assay, GLC3-EGFRvIII cells had a approximately 5-fold increased invasion compared with uninduced GLC3-EGFRvIII, GLC3-Tet-On and the parental cell line. GLC3-Tet-On appeared uniform in size with adherence junctions at cell-cell contacts. In uninduced GLC3-EGFRvIII cells adherence junctions were also present but less distinct. In doxycycline-pretreated GLC3-EGFRvIII cells, adherence junctions were absent. We conclude that the expression of EGFRvIII results in a more malignant phenotype. This effect appears to involve the disruption of adherence junctions. Copyright 2002 Wiley-Liss, Inc.

  3. Tick receptor for outer surface protein A from Ixodes ricinus — the first intrinsically disordered protein involved in vector-microbe recognition

    Science.gov (United States)

    Urbanowicz, Anna; Lewandowski, Dominik; Szpotkowski, Kamil; Figlerowicz, Marek

    2016-04-01

    The tick receptor for outer surface protein A (TROSPA) is the only identified factor involved in tick gut colonization by various Borrelia species. TROSPA is localized in the gut epithelium and can recognize and bind the outer surface bacterial protein OspA via an unknown mechanism. Based on earlier reports and our latest observations, we considered that TROSPA would be the first identified intrinsically disordered protein (IDP) involved in the interaction between a vector and a pathogenic microbe. To verify this hypothesis, we performed structural studies of a TROSPA mutant from Ixodes ricinus using both computational and experimental approaches. Irrespective of the method used, we observed that the secondary structure content of the TROSPA polypeptide chain is low. In addition, the collected SAXS data indicated that this protein is highly extended and exists in solution as a set of numerous conformers. These features are all commonly considered hallmarks of IDPs. Taking advantage of our SAXS data, we created structural models of TROSPA and proposed a putative mechanism for the TROSPA-OspA interaction. The disordered nature of TROSPA may explain the ability of a wide spectrum of Borrelia species to colonize the tick gut.

  4. 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

  5. Role of Site-Specific N-Glycans Expressed on GluA2 in the Regulation of Cell Surface Expression of AMPA-Type Glutamate Receptors.

    Directory of Open Access Journals (Sweden)

    Yusuke Takeuchi

    Full Text Available The AMPA-type glutamate receptor (AMPAR, which is a tetrameric complex composed of four subunits (GluA1-4 with several combinations, mediates the majority of rapid excitatory synaptic transmissions in the nervous system. Cell surface expression levels of AMPAR modulate synaptic plasticity, which is considered one of the molecular bases for learning and memory formation. To date, a unique trisaccharide (HSO3-3GlcAβ1-3Galβ1-4GlcNAc, human natural killer-1 (HNK-1 carbohydrate, was found expressed specifically on N-linked glycans of GluA2 and regulated the cell surface expression of AMPAR and the spine maturation process. However, evidence that the HNK-1 epitope on N-glycans of GluA2 directly affects these phenomena is lacking. Moreover, it is thought that other N-glycans on GluA2 also have potential roles in the regulation of AMPAR functions. In the present study, using a series of mutants lacking potential N-glycosylation sites (N256, N370, N406, and N413 within GluA2, we demonstrated that the mutant lacking the N-glycan at N370 strongly suppressed the intracellular trafficking of GluA2 from the endoplasmic reticulum (ER in HEK293 cells. Cell surface expression of GluA1, which is a major subunit of AMPAR in neurons, was also suppressed by co-expression of the GluA2 N370S mutant. The N370S mutant and wild-type GluA2 were co-immunoprecipitated with GluA1, suggesting that N370S was properly associated with GluA1. Moreover, we found that N413 was the main potential site of the HNK-1 epitope that promoted the interaction of GluA2 with N-cadherin, resulting in enhanced cell surface expression of GluA2. The HNK-1 epitope on N-glycan at the N413 of GluA2 was also involved in the cell surface expression of GluA1. Thus, our data suggested that site-specific N-glycans on GluA2 regulate the intracellular trafficking and cell surface expression of AMPAR.

  6. Distinguishing aggregate formation and aggregate clearance using cell-based assays

    NARCIS (Netherlands)

    Eenjes, E. (Evelien); Dragich, J.M. (Joanna M.); H. Kampinga (Harm); Yamamoto, A. (Ai)

    2016-01-01

    textabstractThe accumulation of ubiquitylated proteinaceous inclusions represents a complex process, reflecting the disequilibrium between aggregate formation and aggregate clearance. Although decreasing aggregate formation or augmenting aggregate clearance will ultimately lead to a diminished

  7. SHAPE ANALYSIS OF FINE AGGREGATES USED FOR CONCRETE

    Directory of Open Access Journals (Sweden)

    Huan He

    2016-12-01

    Full Text Available Fine aggregate is one of the essential components in concrete and significantly influences the material properties. As parts of natures, physical characteristics of fine aggregate are highly relevant to its behaviors in concrete. The most of previous studies are mainly focused on the physical properties of coarse aggregate due to the equipment limitations. In this paper, two typical fine aggregates, i.e. river sand and crushed rock, are selected for shape characterization. The new developed digital image analysis systems are employed as the main approaches for the purpose. Some other technical methods, e.g. sieve test, laser diffraction method are also used for the comparable references. Shape characteristics of fine aggregates with different origins but in similar size ranges are revealed by this study. Compared with coarse aggregate, fine grains of different origins generally have similar shape differences. These differences are more significant in surface texture properties, which can be easily identified by an advanced shape parameter: bluntness. The new image analysis method is then approved to be efficient for the shape characterization of fine aggregate in concrete.

  8. Physical enviroment of 2-D animal cell aggregates formed in a short pathlength ultrasound standing wave trap.

    Science.gov (United States)

    Bazou, Despina; Kuznetsova, Larisa A; Coakley, W Terence

    2005-03-01

    2-D mammalian cell aggregates can be formed and levitated in a 1.5 MHz single half wavelength ultrasound standing wave trap. The physical environment of cells in such a trap has been examined. Attention was paid to parameters such as temperature, acoustic streaming, cavitation and intercellular forces. The extent to which these factors might be intrusive to a neural cell aggregate levitated in the trap was evaluated. Neural cells were exposed to ultrasound at a pressure amplitude of 0.54 MPa for 30 s; a small aggregate had been formed at the center of the trap. The pressure amplitude was then decreased to 0.27 MPa for 2 min, at which level the aggregation process continued at a slower rate. The pressure amplitude was then decreased to 0.06 MPa for 1 h. Temperature measurements that were conducted in situ with a 200 microm thermocouple over a 30 min period showed that the maximum temperature rise was less than 0.5 K. Acoustic streaming was measured by the particle image velocimetry method (PIV). It was shown that the hydrodynamic stress imposed on cells by acoustic streaming is less than that imposed by gentle preparative centrifugation procedures. Acoustic spectrum analysis showed that cavitation activity does not occur in the cell suspensions sonicated at the above pressures. White noise was detected only at a pressure amplitude of 1.96 MPa. Finally, it was shown that the attractive acoustic force between ultrasonically agglomerated cells is small compared with the normal attractive van der Waals force that operates at close cell surface separations. It is concluded that the standing wave trap operates only to concentrate cells locally, as in tissue, and does not modify the in vitro expression of surface receptor interactions.

  9. CD3+ CD4+ and CD3+ CD8+ lymphocyte subgroups and their surface receptors NKG2D and NKG2A in patients with non-small cell lung cancer.

    Science.gov (United States)

    Yu, Da-Ping; Han, Yi; Zhao, Qiu-Yue; Liu, Zhi-Dong

    2014-01-01

    To explore the prevalence of lymphocyte subgroups CD3+ CD4+ and CD3+ CD8+ and their surface receptors NKG2D and NKG2A in patients with non-small cell lung cancer (NSCLC). A total of 40 patients with NSCLC were divided into different groups according to different clinical factors (TNM staging, pathological patterns and genders) for assessment of relations with CD3+ CD4+ and CD3+ CD8+ and the surface receptors NKG2D and NKG2A of T lymphocytes in peripheral blood by flow cytometry. Patients in the advanced group had evidently lower levels of CD3+ CD4+ but markedly higher levels of CD3+ CD8+ in peripheral blood than those with early lesions (pCD3+ CD4+ NKG2D and CD3+ CD8+ NKG2A expression rates but lower CD3+ CD4+ NKG2A and CD3+ CD8+ NKG2D expression rates (pCD3+ CD4+ and CD3+ CD8+ and their surface receptors NKG2D and NKG2A. Unbalanced expression of surface receptors NKG2D and NKG2A in CD3+ CD4+ and CD3+ CD8+ lymphocytes may be associated with a poor prognosis, greater malignancy and immunological evasion by advanced cancers, related to progression of lung cancer.

  10. Reactivation of persistent Epstein-Barr virus (EBV) causes secretion of thyrotropin receptor antibodies (TRAbs) in EBV-infected B lymphocytes with TRAbs on their surface.

    Science.gov (United States)

    Nagata, Keiko; Nakayama, Yuji; Higaki, Katsumi; Ochi, Marika; Kanai, Kyosuke; Matsushita, Michiko; Kuwamoto, Satoshi; Kato, Masako; Murakami, Ichiro; Iwasaki, Takeshi; Nanba, Eiji; Kimura, Hiroshi; Hayashi, Kazuhiko

    2015-01-01

    Epstein-Barr virus (EBV) is a ubiquitous virus that infects most adults latently. It persists in B lymphocytes and reactivates occasionally. Graves' disease is an autoimmune hyperthyroidism caused by thyrotropin receptor antibodies (TRAbs). We have reported that Graves' disease patients and healthy controls have EBV-infected lymphocytes that have TRAbs on their surface (TRAb(+)EBV(+) cells) in peripheral blood mononuclear cells (PBMCs). EBV reactivation is known to be associated with plasma cell differentiation and antibody production of B cells. In this study, we investigated whether TRAb(+)EBV(+) cells really produce TRAbs or not when persistent EBV is reactivated. We cultured PBMCs from 12 Graves' disease patients and 12 healthy controls for several days with cyclosporine A to expand the EBV-infected cell population, and then compared TRAb levels between EBV reactivation by 33 °C culture and EBV nonreactivation by 37 °C culture of PBMCs. Flow cytometry confirmed that all samples at day 0 (reactivation starting point) contained TRAb(+)EBV(+) cells. During 33 °C culture, EBV-reactivated cells with EBV-gp350/220 expression increased from about 1 to 4%. We quantified TRAb levels in culture fluids by radio-receptor assay, and detected an increased concentration for at least one sampling point at 33 °C (from days 0 to 12) for all patients and healthy controls. TRAb levels were significantly higher in supernatants of 33 °C culture than of 37 °C culture, and also significantly higher in supernatants from patients than those from controls. This study revealed TRAb production from TRAb(+)EBV(+) cells in response to reactivation induction of persistent EBV in different efficiencies between patients and controls.

  11. Identification of a ligand for tumor necrosis factor receptor from Chinese herbs by combination of surface plasmon resonance biosensor and UPLC-MS.

    Science.gov (United States)

    Cao, Yan; Li, Ying-Hua; Lv, Di-Ya; Chen, Xiao-Fei; Chen, Lang-Dong; Zhu, Zhen-Yu; Chai, Yi-Feng; Zhang, Jun-Ping

    2016-07-01

    Identification of bioactive compounds directly from complex herbal extracts is a key issue in the study of Chinese herbs. The present study describes the establishment and application of a sensitive, efficient, and convenient method based on surface plasmon resonance (SPR) biosensors for screening active ingredients targeting tumor necrosis factor receptor type 1 (TNF-R1) from Chinese herbs. Concentration-adjusted herbal extracts were subjected to SPR binding assay, and a remarkable response signal was observed in Rheum officinale extract. Then, the TNF-R1-bound ingredients were recovered, enriched, and analyzed by UPLC-QTOF/MS. As a result, physcion-8-O-β-D-monoglucoside (PMG) was identified as a bioactive compound, and the affinity constant of PMG to TNF-R1 was determined by SPR affinity analysis (K D  = 376 nM). Pharmacological assays revealed that PMG inhibited TNF-α-induced cytotoxicity and apoptosis in L929 cells via TNF-R1. Although PMG was a trace component in the chemical constituents of the R. officinale extract, it had considerable anti-inflammatory activities. It was found for the first time that PMG was a ligand for TNF receptor from herbal medicines. The proposed SPR-based screening method may prove to be an effective solution to analyzing bioactive components of Chinese herbs and other complex drug systems. Graphical abstract Scheme of the method based on SPR biosensor for screening and recovering active ingredients from complex herbal extracts and UPLC-MS for identifying them. Scheme of the method based on SPR biosensor for screening and recovering active ingredients from complex herbal extracts and UPLC-MS for identifying them.

  12. Perturbing Streaming in Dictyostelium discoidium Aggregation

    Science.gov (United States)

    Rericha, Erin; Garcia, Gene; Parent, Carole; Losert, Wolfgang

    2009-03-01

    The ability of cells to move towards environmental cues is a critical process allowing the destruction of intruders by the immune system, the formation of the vascular system and the whole scale remodeling of tissues during embryo development. We examine the initial transition from single cell to group migration in the social amoeba Dictyostelium discoidium. Upon starvation, D. discoidium cells enter into a developmental program that triggers solitary cells to aggregate into a multicellular structure. The aggregation is mediated by the small molecule, cyclic-AMP, that cells sense, synthesize, secrete and migrate towards often in a head-to-tail fashion called a stream. Using experiment and numerical simulation, we study the sensitivity of streams to perturbations in the cyclic-AMP concentration field. We find the stability of the streams requires cells to shape the cyclic-AMP field through localized secretion and degradation. In addition, we find the streaming phenotype is sensitive to changes in the substrate properties, with slicker surfaces leading to longer more branched streams that yield large initial aggregates.

  13. Multivalent scaffolds induce galectin-3 aggregation into nanoparticles

    Directory of Open Access Journals (Sweden)

    Candace K. Goodman

    2014-07-01

    Full Text Available Galectin-3 meditates cell surface glycoprotein clustering, cross linking, and lattice formation. In cancer biology, galectin-3 has been reported to play a role in aggregation processes that lead to tumor embolization and survival. Here, we show that lactose-functionalized dendrimers interact with galectin-3 in a multivalent fashion to form aggregates. The glycodendrimer–galectin aggregates were characterized by dynamic light scattering and fluorescence microscopy methodologies and were found to be discrete particles that increased in size as the dendrimer generation was increased. These results show that nucleated aggregation of galectin-3 can be regulated by the nucleating polymer and provide insights that improve the general understanding of the binding and function of sugar-binding proteins.

  14. Shaping the growth behaviour of biofilms initiated from bacterial aggregates

    DEFF Research Database (Denmark)

    Melaugh, Gavin; Hutchison, Jaime; Kragh, Kasper Nørskov

    2016-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell ag...... outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the social evolution of biofilm communities....

  15. Cloning and expression of the receptor for human urokinase plasminogen activator, a central molecule in cell surface, plasmin dependent proteolysis

    DEFF Research Database (Denmark)

    Roldan, A L; Cubellis, M V; Masucci, M T

    1990-01-01

    , and therefore the capacity of cells to migrate and invade neighboring tissues. We have isolated a 1.4 kb cDNA clone coding for the entire human uPAR. An oligonucleotide synthesized on the basis of the N-terminal sequence of the purified protein was used to screen a cDNA library made from SV40 transformed human......, a size very close to that of the cloned cDNA. Expression of the uPAR cDNA in mouse cells confirms that the clone is complete and expresses a functional uPA binding protein, located on the cell surface and with properties similar to the human uPAR. Caseinolytic plaque assay, immunofluorescence analysis...... fibroblasts [Okayama and Berg (1983) Mol. Cell Biol., 3, 280-289]. The cDNA encodes a protein of 313 amino acids, preceded by a 21 residue signal peptide. A hydrophobicity plot suggests the presence of a membrane spanning domain close to the C-terminus. The cDNA hybridizes to a 1.4 kb mRNA from human cells...

  16. Cloning and expression of the receptor for human urokinase plasminogen activator, a central molecule in cell surface, plasmin dependent proteolysis

    DEFF Research Database (Denmark)

    Roldan, A.L.; Cubellis, M.V.; Masucci, M.T.

    1990-01-01

    , and therefore the capacity of cells to migrate and invade neighboring tissues. We have isolated a 1.4 kb cDNA clone coding for the entire human uPAR. An oligonucleotide synthesized on the basis of the N-terminal sequence of the purified protein was used to screen a cDNA library made from SV40 transformed human...... fibroblasts [Okayama and Berg (1983) Mol. Cell Biol., 3, 280-289]. The cDNA encodes a protein of 313 amino acids, preceded by a 21 residue signal peptide. A hydrophobicity plot suggests the presence of a membrane spanning domain close to the C-terminus. The cDNA hybridizes to a 1.4 kb mRNA from human cells......, a size very close to that of the cloned cDNA. Expression of the uPAR cDNA in mouse cells confirms that the clone is complete and expresses a functional uPA binding protein, located on the cell surface and with properties similar to the human uPAR. Caseinolytic plaque assay, immunofluorescence analysis...

  17. Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine.

    Science.gov (United States)

    Kahler, Amy M; Cromeans, Theresa L; Metcalfe, Maureen G; Humphrey, Charles D; Hill, Vincent R

    2016-06-01

    It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with human adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.

  18. Characterization of Boron Atom Aggregation

    National Research Council Canada - National Science Library

    Maier, John P

    2005-01-01

    ... in matrices ranging from neon to those doped with hydrogen. The studies of the aggregation properties were hampered by the lack of spectroscopic knowledge on the electronic transitions of the polyatomic boron molecules and their ions...

  19. Aggregated Computational Toxicology Resource (ACTOR)

    Science.gov (United States)

    The Aggregated Computational Toxicology Resource (ACTOR) is a database on environmental chemicals that is searchable by chemical name and other identifiers, and by chemical structure. This information is consolidated from more than 200 publicly available sources of data.

  20. Cell surface-bound TIMP3 induces apoptosis in mesenchymal Cal78 cells through ligand-independent activation of death receptor signaling and blockade of survival pathways.

    Directory of Open Access Journals (Sweden)

    Christina Koers-Wunrau

    Full Text Available BACKGROUND: The matrix metalloproteinases (MMPs and their endogenous regulators, the tissue inhibitor of metalloproteinases (TIMPs 1-4 are responsible for the physiological remodeling of the extracellular matrix (ECM. Among all TIMPs, TIMP3 appears to play a unique role since TIMP3 is a secreted protein and, unlike the other TIMP family members, is tightly bound to the ECM. Moreover TIMP3 has been shown to be able to induce apoptotic cell death. As little is known about the underlying mechanisms, we set out to investigate the pro-apoptotic effect of TIMP3 in human mesenchymal cells. METHODOLOGY/PRINCIPAL FINDINGS: Lentiviral overexpression of TIMP3 in mesenchymal cells led to a strong dose-dependent induction of ligand-independent apoptosis as reflected by a five-fold increase in caspase 3 and 7 activity compared to control (pLenti6/V5-GW/lacZ or uninfected cells, whereas exogenous TIMP3 failed to induce apoptosis. Concordantly, increased cleavage of death substrate PARP and the caspases 3 and 7 was observed in TIMP3 overexpressing cultures. Notably, activation of caspase-8 but not caspase-9 was observed in TIMP3-overexpressing cells, indicating a death receptor-dependent mechanism. Moreover, overexpression of TIMP3 led to a further induction of apoptosis after stimulation with TNF-alpha, FasL and TRAIL. Most interestingly, TIMP3-overexpression was associated with a decrease in phosphorylation of cRaf, extracellular signal-regulated protein kinase (Erk1/2, ribosomal S6 kinase (RSK1 and Akt and serum deprivation of TIMP3-overexpressing cells resulted in a distinct enhancement of apoptosis, pointing to an impaired signaling of serum-derived survival factors. Finally, heparinase treatment of heparan sulfate proteoglycans led to the release of TIMP3 from the surface of overexpressing cells and to a significant decrease in apoptosis indicating that the binding of TIMP3 is necessary for apoptosis induction. CONCLUSION: The results demonstrate that

  1. N-linked glycosylation is required for transferrin-induced stabilization of transferrin receptor 2, but not for transferrin binding or trafficking to the cell surface.

    Science.gov (United States)

    Zhao, Ningning; Enns, Caroline A

    2013-05-14

    Transferrin receptor 2 (TfR2) is a member of the transferrin receptor-like family of proteins. Mutations in TfR2 can lead to a rare form of the iron overload disease, hereditary hemochromatosis. TfR2 is proposed to sense body iron levels and increase the level of expression of the iron regulatory hormone, hepcidin. Human TfR2 (hTfR2) contains four potential Asn-linked (N-linked) glycosylation sites on its ectodomain. The importance of glycosylation in TfR2 function has not been elucidated. In this study, by employing site-directed mutagenesis to remove glycosylation sites of hTfR2 individually or in combination, we found that hTfR2 was glycosylated at Asn 240, 339, and 754, while the consensus sequence for N-linked glycosylation at Asn 540 was not utilized. Cell surface protein biotinylation and biotin-labeled Tf indicated that in the absence of N-linked oligosaccharides, hTfR2 still moved to the plasma membrane and bound its ligand, holo-Tf. However, without N-linked glycosylation, hTfR2 did not form the intersubunit disulfide bonds as efficiently as the wild type (WT). Moreover, the unglycosylated form of hTfR2 could not be stabilized by holo-Tf. We further provide evidence that the unglycosylated hTfR2 behaved in manner different from that of the WT in response to holo-Tf treatment. Thus, the putative iron-sensing function of TfR2 could not be achieved in the absence of N-linked oligosaccharides. On the basis of our analyses, we conclude that unlike TfR1, N-linked glycosylation is dispensable for the cell surface expression and holo-Tf binding, but it is required for efficient intersubunit disulfide bond formation and holo-Tf-induced stabilization of TfR2.

  2. Rinsing paired-agent model (RPAM) to quantify cell-surface receptor concentrations in topical staining applications of thick tissues.

    Science.gov (United States)

    Xu, Xiaochun; Wang, Yu; Xiang, Jialing; Liu, Jonathan T C; Tichauer, Kenneth M

    2017-06-21

    Conventional molecular assessment of tissue through histology, if adapted to fresh thicker samples, has the potential to enhance cancer detection in surgical margins and monitoring of 3D cell culture molecular environments. However, in thicker samples, substantial background staining is common despite repeated rinsing, which can significantly reduce image contrast. Recently, 'paired-agent' methods-which employ co-administration of a control (untargeted) imaging agent-have been applied to thick-sample staining applications to account for background staining. To date, these methods have included (1) a simple ratiometric method that is relatively insensitive to noise in the data but has accuracy that is dependent on the staining protocol and the characteristics of the sample; and (2) a complex paired-agent kinetic modeling method that is more accurate but is more noise-sensitive and requires a precise serial rinsing protocol. Here, a new simplified mathematical model-the rinsing paired-agent model (RPAM)-is derived and tested that offers a good balance between the previous models, is adaptable to arbitrary rinsing-imaging protocols, and does not require calibration of the imaging system. RPAM is evaluated against previous models and is validated by comparison to estimated concentrations of targeted biomarkers on the surface of 3D cell culture and tumor xenograft models. This work supports the use of RPAM as a preferable model to quantitatively analyze targeted biomarker concentrations in topically stained thick tissues, as it was found to match the accuracy of the complex paired-agent kinetic model while retaining the low noise-sensitivity characteristics of the ratiometric method.

  3. Rinsing paired-agent model (RPAM) to quantify cell-surface receptor concentrations in topical staining applications of thick tissues

    Science.gov (United States)

    Xu, Xiaochun; Wang, Yu; Xiang, Jialing; Liu, Jonathan T. C.; Tichauer, Kenneth M.

    2017-06-01

    Conventional molecular assessment of tissue through histology, if adapted to fresh thicker samples, has the potential to enhance cancer detection in surgical margins and monitoring of 3D cell culture molecular environments. However, in thicker samples, substantial background staining is common despite repeated rinsing, which can significantly reduce image contrast. Recently, ‘paired-agent’ methods—which employ co-administration of a control (untargeted) imaging agent—have been applied to thick-sample staining applications to account for background staining. To date, these methods have included (1) a simple ratiometric method that is relatively insensitive to noise in the data but has accuracy that is dependent on the staining protocol and the characteristics of the sample; and (2) a complex paired-agent kinetic modeling method that is more accurate but is more noise-sensitive and requires a precise serial rinsing protocol. Here, a new simplified mathematical model—the rinsing paired-agent model (RPAM)—is derived and tested that offers a good balance between the previous models, is adaptable to arbitrary rinsing-imaging protocols, and does not require calibration of the imaging system. RPAM is evaluated against previous models and is validated by comparison to estimated concentrations of targeted biomarkers on the surface of 3D cell culture and tumor xenograft models. This work supports the use of RPAM as a preferable model to quantitatively analyze targeted biomarker concentrations in topically stained thick tissues, as it was found to match the accuracy of the complex paired-agent kinetic model while retaining the low noise-sensitivity characteristics of the ratiometric method.

  4. Aggregation behavior and total miscibility of fluorinated ionic liquids in water.

    Science.gov (United States)

    Pereiro, Ana B; Araújo, João M M; Teixeira, Fabiana S; Marrucho, Isabel M; Piñeiro, Manuel M; Rebelo, Luis Paulo N

    2015-02-03

    In this work, novel and nontoxic fluorinated ionic liquids (FILs) that are totally miscible in water and could be used in biological applications, where fluorocarbon compounds present a handicap because their aqueous solubility (water and biological fluids) is in most cases too low, have been investigated. The self-aggregation behavior of perfluorosulfonate-functionalized ionic liquids in aqueous solutions has been characterized using conductometric titration, isothermal titration calorimetry (ITC), surface tension measurements, dynamic light scattering (DLS), viscosity and density measurements, and transmission electron microscopy (TEM). Aggregation and interfacial parameters have been computed by conductimetry, calorimetry, and surface tension measurements in order to study various thermodynamic and surface properties that demonstrate that the aggregation process is entropy-driven and that the aggregation process is less spontaneous than the adsorption process. The novel perfluorosulfonate-functionalized ILs studied in this work show improved surface activity and aggregation behavior, forming distinct self-assembled structures.

  5. Nitric oxide regulates the aggregation of stimulated human neutrophils.

    Science.gov (United States)

    Forslund, T; Nilsson, H M; Sundqvist, T

    2000-08-02

    Neutrophil aggregation is mediated by both CD18 integrin and L-selectin. Nitric oxide attenuates the integrin-mediated adhesion of neutrophils to collagen and to endothelium and may therefore affect aggregation as well. FMLP-stimulated neutrophils exposed to l-arginine showed increased and prolonged aggregation, whereas cells pretreated with L-NAME did not differ from FMLP-stimulated controls. Nitric oxide is known to induce ADP ribosylation of G-actin, which inhibits polymerization. We detected equivalent levels of total F-actin in cells pretreated with l-arginine or L-NAME and non-pretreated controls. However, neutrophils pretreated with l-arginine and stimulated by CD18 integrin cross-linking exhibited a more limited increase in total F-actin, compared to control and L-NAME-pretreated cells. Thus at least two signaling pathways may be involved FMLP-stimulated aggregation, mediated by CD18 integrins. More specifically, it is plausible that FMLP-receptor signaling upregulates CD18 integrins and endogenous NO subsequently modulates CD18-mediated signaling to prolong aggregation, possibly through ADP-ribosylation of actin. Copyright 2000 Academic Press.

  6. Aggregation-Enhanced Raman Scattering by a Water-Soluble Porphyrin

    Science.gov (United States)

    Akins, Daniel L.

    1995-01-01

    Much interest in our laboratory has focused on aggregation of organic compounds, particularly cyanine dyes and porphyrins. For this discussion we have applied absorption and Raman scattering spectroscopies to characterize aggregated TSPP (tetrakis-(p-sulfonatophynyl) porphyrin) in aqueous solution. Based on concentration, pH and ionic strength dependence of TSPP absorption, we deduce that aggregation evolves through the formation of TSPP diacid and that the diacid is the repeating unit in the aggregate. The Raman bands of TSPP in strongly acidic solution lead us further to conclude that vibrations of adjacent molecules are perturbed in a fashion that is consistent with the pyrrolic ring in the porphinato macrocycle being ruffled, and that two aggregate arrangements occur: specifically J- and H-type aggregates. Furthermore, aggregation enhancement is advanced as a viable mechanism to explain enhanced Raman Scattering for homogeneous aqueous phase TSPP, where the surface-enhancement mechanism is not applicable.

  7. Activation of murine macrophages by Neisseria meningitidis and IFN-gamma in vitro: distinct roles of class A scavenger and Toll-like pattern recognition receptors in selective modulation of surface phenotype.

    Science.gov (United States)

    Mukhopadhyay, Subhankar; Peiser, Leanne; Gordon, Siamon

    2004-09-01

    Innate and adaptive immune activation of macrophages (Mphi) by microorganisms and antigen-activated lymphoid cells, respectively, plays an important role in host defense and immunopathology. Antigen-presenting cells express a range of pattern recognition receptors including the class A types I and II scavenger receptors (SR-A) and Toll-like receptors (TLR). Recognition of microbial products by SR-A and TLR controls uptake, killing, altered gene expression, and the adaptive immune response; however, the contribution of each receptor and interplay with cytokine stimuli such as interferon-gamma (IFN-gamma) are not defined. We used Neisseria meningitidis (NM), a potent activator of innate immunity, and IFN-gamma, a prototypic T helper cell type 1 proinflammatory cytokine, to compare surface antigens, secretion of mediators, and receptor functions in elicited peritoneal Mphi from wild-type and genetically modified mouse strains. We show that these stimuli regulate major histocompatibility complex type II (MHC-II) and costimulatory molecules differentially, as well as expression of the mannose receptor and of Mphi receptor with collagenous structure (MARCO), a distinct SR-A, which provides a selective marker for innate activation. In combination, NM inhibited up-regulation of MHC-II by IFN-gamma while priming enhanced release of tumor necrosis factor alpha and nitric oxide. The SR-A contributes to phagocytosis of the organisms but not to their ability to induce CD80, CD86, and MARCO or to inhibit MHC-II. Conversely, studies with lipopolysaccharide (LPS)-deficient organisms and/or TLR-4 mutant mice showed that LPS and TLR-4 are at least partially required to induce CD80, CD86, and MARCO, but LPS is not required to inhibit MHC-II. These studies provide an experimental model and identify surface markers for analysis of innate and acquired immune activation of Mphi.

  8. Electrochemical sensors and biosensors based on less aggregated graphene.

    Science.gov (United States)

    Bo, Xiangjie; Zhou, Ming; Guo, Liping

    2017-03-15

    As a novel single-atom-thick sheet of sp 2 hybridized carbon atoms, graphene (GR) has attracted extensive attention in recent years because of its unique and remarkable properties, such as excellent electrical conductivity, large theoretical specific surface area, and strong mechanical strength. However, due to the π-π interaction, GR sheets are inclined to stack together, which may seriously degrade the performance of GR with the unique single-atom layer. In recent years, an increasing number of GR-based electrochemical sensors and biosensors are reported, which may reflect that GR has been considered as a kind of hot and promising electrode material for electrochemical sensor and biosensor construction. However, the active sites on GR surface induced by the irreversible GR aggregations would be deeply secluded inside the stacked GR sheets and therefore are not available for the electrocatalysis. So the alleviation or the minimization of the aggregation level for GR sheets would facilitate the exposure of active sites on GR and effectively upgrade the performance of GR-based electrochemical sensors and biosensors. Less aggregated GR with low aggregation and high dispersed structure can be used in improving the electrochemical activity of GR-based electrochemical sensors or biosensors. In this review, we summarize recent advances and new progress for the development of electrochemical sensors based on less aggregated GR. To achieve such goal, many strategies (such as the intercalation of carbon materials, surface modification, and structural engineering) have been applied to alleviate the aggregation level of GR in order to enhance the performance of GR-based electrochemical sensors and biosensors. Finally, the challenges associated with less aggregated GR-based electrochemical sensors and biosensors as well as related future research directions are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Investigation of the mechanisms by which the molecular chaperone HSPA2 regulates the expression of sperm surface receptors involved in human sperm-oocyte recognition.

    Science.gov (United States)

    Redgrove, Kate A; Anderson, Amanda L; McLaughlin, Eileen A; O'Bryan, Moira K; Aitken, R John; Nixon, Brett

    2013-03-01

    A unique characteristic of mammalian spermatozoa is that, upon ejaculation, they are unable to recognize and bind to an ovulated oocyte. These functional attributes are only realized following the cells' ascent of the female reproductive tract whereupon they undergo a myriad of biochemical and biophysical changes collectively referred to as 'capacitation'. We have previously shown that this functional transformation is, in part, engineered by the modification of the sperm surface architecture leading to the assembly and/or presentation of multimeric sperm-oocyte receptor complexes. In this study, we have extended our findings through the characterization of one such complex containing arylsulfatase A (ARSA), sperm adhesion molecule 1 (SPAM1) and the molecular chaperone, heat shock 70kDa protein 2 (HSPA2). Through the application of flow cytometry we revealed that this complex undergoes a capacitation-associated translocation to facilitate the repositioning of ARSA to the apical region of the human sperm head, a location compatible with a role in the mediation of sperm-zona pellucida (ZP) interactions. Conversely, SPAM1 appears to reorient away from the sperm surface, possibly reflecting its primary role in cumulus matrix dispersal preceding sperm-ZP recognition. The dramatic relocation of the complex was completely abolished by incubation of capacitating spermatozoa in exogenous cholesterol or broad spectrum protein kinase A (PKA) and tyrosine kinase inhibitors suggesting that it may be driven by alterations in membrane fluidity characteristics and concurrently by the activation of a capacitation-associated signal transduction pathway. Collectively these data afford novel insights into the sub-cellular localization and potential functions of multimeric protein complexes in human spermatozoa.

  10. Voltammetric Detection of S100B Protein Using His-Tagged Receptor Domains for Advanced Glycation End Products (RAGE Immobilized onto a Gold Electrode Surface

    Directory of Open Access Journals (Sweden)

    Edyta Mikuła

    2014-06-01

    Full Text Available In this work we report on an electrochemical biosensor for the determination of the S100B protein. The His-tagged VC1 domains of Receptors for Advanced Glycation End (RAGE products used as analytically active molecules were covalently immobilized on a monolayer of a thiol derivative of pentetic acid (DPTA complex with Cu(II deposited on a gold electrode surface. The recognition processes between the RAGE VC1 domain and the S100B protein results in changes in the redox activity of the DPTA-Cu(II centres which were measured by Osteryoung square-wave voltammetry (OSWV. In order to verify whether the observed analytical signal originates from the recognition process between the His6–RAGE VC1 domains and the S100B protein, the electrode modified with the His6–RAGE C2 and His6–RAGE VC1 deleted domains which have no ability to bind S100B peptides were applied. The proposed biosensor was quite sensitive, with a detection limit of 0.52 pM recorded in the buffer solution. The presence of diluted human plasma and 10 nM Aβ1-40 have no influence on the biosensor performance.

  11. Aggregation mechanism of an IgG2 and two IgG1 monoclonal antibodies at low pH: from oligomers to larger aggregates.

    Science.gov (United States)

    Arosio, Paolo; Rima, Simonetta; Morbidelli, Massimo

    2013-03-01

    To identify the aggregation mechanism and the stability characteristics of three different monoclonal antibodies under acidic conditions. The aggregation kinetics is analyzed by a combination of light scattering, size exclusion chromatography and fluorescence techniques and the aggregation data are correlated to protein structure, hydrophobicity, charge and antibody subclass. In the investigated conditions, the antibody aggregation follows a mechanism consisting of two-steps: reversible monomer oligomerization followed by irreversible cluster-cluster aggregation. The kinetics of the two steps is differently affected by the operating conditions: mild destabilizing conditions induce formation of oligomers which are stable within weeks, while stronger denaturing conditions promote aggregation of oligomers to larger aggregates which eventually precipitate. For different antibodies significant differences in both oligomerization and growth rates are found, even for antibodies belonging to the same subclass. For all antibodies the aggregate formation is accompanied by a structure re-organization with an increase in the ordered β-sheet structures. At low pH the aggregation propensity of the investigated antibodies does not correlate with antibody subclass, surface net charge and hydrophobicity of the non-native state. The aggregation mechanism of three antibodies in acidic conditions as well as differences and analogies in their stability behavior has been characterized.

  12. Benthic life in the pelagic: Aggregate encounter and degradation rates by pelagic harpacticoid copepods

    DEFF Research Database (Denmark)

    Koski, Marja; Kiørboe, Thomas; Takahashi, K.

    2005-01-01

    We measured field abundances, feeding rates, swimming behavior, and particle colonization of two harpacticoids, the pelagic Microsetella norvegica and the semibenthic Amonardia normanni, to examine (1) if aggregates have a significant role in harpacticoid nutrition and (2) if harpacticoids...... contribute significantly to aggregate degradation. Neither of the harpacticoids was able to feed efficiently on suspended food, while both grazed well on attached food, indicating that pelagic harpacticoids depend on food attached to surfaces, such as those offered by marine aggregates. We estimated...

  13. Porous Pavers: Effects of the Recycled Aggregate Size on Drainage Properties

    OpenAIRE

    Abdul Ghani A.N.; Cheong P.C.

    2014-01-01

    Pervious pavers allow water to percolate through the pavement surface. One of its functions is to reduce runoff. This research studies the possible usage of recycled aggregates as the main base material for pervious pavers. Recycled aggregates are produced by crushing waste concrete and mixing with a non-cement, epoxy binder to produce a pervious pavement. The samples were tested for permeability, porosity and compressive strength. The effects of using recycled aggregates and epoxy binders on...

  14. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  15. A Functional Reference Architecture for Aggregators

    DEFF Research Database (Denmark)

    Bondy, Daniel Esteban Morales; Heussen, Kai; Gehrke, Oliver

    2015-01-01

    Aggregators are considered to be a key enabling technology for harvesting power system services from distributed energy resources (DER). As a precondition for more widespread use of aggregators in power systems, methods for comparing and validating aggregator designs must be established. This paper...... proposes a functional reference architecture for aggregators to address this requirement....

  16. Aggregated Recommendation through Random Forests

    Directory of Open Access Journals (Sweden)

    Heng-Ru Zhang

    2014-01-01

    Full Text Available Aggregated recommendation refers to the process of suggesting one kind of items to a group of users. Compared to user-oriented or item-oriented approaches, it is more general and, therefore, more appropriate for cold-start recommendation. In this paper, we propose a random forest approach to create aggregated recommender systems. The approach is used to predict the rating of a group of users to a kind of items. In the preprocessing stage, we merge user, item, and rating information to construct an aggregated decision table, where rating information serves as the decision attribute. We also model the data conversion process corresponding to the new user, new item, and both new problems. In the training stage, a forest is built for the aggregated training set, where each leaf is assigned a distribution of discrete rating. In the testing stage, we present four predicting approaches to compute evaluation values based on the distribution of each tree. Experiments results on the well-known MovieLens dataset show that the aggregated approach maintains an acceptable level of accuracy.

  17. Influence of uncoated and coated plastic waste coarse aggregates to concrete compressive strength

    Directory of Open Access Journals (Sweden)

    Purnomo Heru

    2017-01-01

    Full Text Available The use of plastic waste as coarse aggregates in concrete is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of the concrete than concrete using natural aggregates, but on the other hand bond between plastic coarse aggregates and hard matrix give low concrete compressive strength. Improvement of the bond between plastic coarse aggregate and hard matrix through a sand coating to plastic coarse aggregate whole surface is studied. Sand used to coat the plastic aggregates are Merapi volcanic sand which are taken in Magelang. Three mixtures of polypropylene (PP coarse plastic aggregates, Cimangkok river sand as fine aggregates, water and Portland Cement Composite with a water-cement ratio of 0.28, 0.3 and 0.35 are conducted. Compression test are performed on concrete cylindrical specimens with a diameter of 10 cm and a height of 20 cm. The results in general show that concrete specimens using plastic aggregates coated with sand have higher compressive strength compared to those of concrete specimens using plastic aggregates without sand coating. The bond improvement is indirectly indicated by the betterment of concrete compressive strength.

  18. The alkali–aggregate reaction for various aggregates used in concrete

    Directory of Open Access Journals (Sweden)

    Calderón, V.

    2010-09-01

    Full Text Available The aim of this work is to contribute to the knowledge of the interactions between aggregates and the components of the interstitial phase of concrete and to determine whether those aggregates that are subsequently used in the manufacture of concrete are reagents and are therefore likely to undergo a progressive deterioration of their initial properties. An initial petrographic study of each aggregate is performed in order to be able to determine its subsequent behaviour and reactivity under the influence of various factors. The potential reactivity of different silicaceous aggregates (slates, gneiss, hornfels, granites, quartzite and serpentine is then determined by a chemical method for evaluating the potential reactivity of aggregates and an accelerated method in mortar specimens, and finally the surface reactivity is investigated. The results of these studies suggest that some aggregates are able to react with the components of the interstitial phase of concrete. The existence of this kind of interaction is confirmed by the results of the surface investigations before and after the basic reaction.

    Este trabajo pretende contribuir al conocimiento de las reacciones de interacción entre los áridos y los componentes de la fase intersticial del hormigón y determinar si estos áridos, empleados posteriormente en la fabricación del hormigón, son reactivos y por tanto susceptibles de provocar una disminución progresiva de sus propiedades iniciales. Para la caracterización de cada árido se ha realizado un estudio petrográfico, fundamental a la hora de determinar su posterior comportamiento en términos de reactividad frente a diversos factores. Seguidamente, se ha analizado la reactividad potencial de diferentes áridos silicatados (pizarras, gneis, corneanas, granitos, cuarcita y serpentina mediante los dos métodos normalizados existentes: el método químico para la determinación de la reactividad potencial de áridos y

  19. Channel Aggregation Schemes for Cognitive Radio Networks

    Science.gov (United States)

    Lee, Jongheon; So, Jaewoo

    This paper proposed three channel aggregation schemes for cognitive radio networks, a constant channel aggregation scheme, a probability distribution-based variable channel aggregation scheme, and a residual channel-based variable channel aggregation scheme. A cognitive radio network can have a wide bandwidth if unused channels in the primary networks are aggregated. Channel aggregation schemes involve either constant channel aggregation or variable channel aggregation. In this paper, a Markov chain is used to develop an analytical model of channel aggregation schemes; and the performance of the model is evaluated in terms of the average sojourn time, the average throughput, the forced termination probability, and the blocking probability. Simulation results show that channel aggregation schemes can reduce the average sojourn time of cognitive users by increasing the channel occupation rate of unused channels in a primary network.

  20. Mapping the energy and diffusion landscapes of membrane proteins at the cell surface using high-density single-molecule imaging and Bayesian inference: application to the multi-scale dynamics of glycine receptors in the neuronal membrane

    CERN Document Server

    Masson, Jean-Baptiste; Salvatico, Charlotte; Renner, Marianne; Specht, Christian G; Triller, Antoine; Dahan, Maxime

    2015-01-01

    Protein mobility is conventionally analyzed in terms of an effective diffusion. Yet, this description often fails to properly distinguish and evaluate the physical parameters (such as the membrane friction) and the biochemical interactions governing the motion. Here, we present a method combining high-density single-molecule imaging and statistical inference to separately map the diffusion and energy landscapes of membrane proteins across the cell surface at ~100 nm resolution (with acquisition of a few minutes). When applying these analytical tools to glycine neurotransmitter receptors (GlyRs) at inhibitory synapses, we find that gephyrin scaffolds act as shallow energy traps (~3 kBT) for GlyRs, with a depth modulated by the biochemical properties of the receptor-gephyrin interaction loop. In turn, the inferred maps can be used to simulate the dynamics of proteins in the membrane, from the level of individual receptors to that of the population, and thereby, to model the stochastic fluctuations of physiologi...

  1. Aggregations of the sandy-beach isopod, Tylos granulatu ...

    African Journals Online (AJOL)

    1995-12-14

    Dec 14, 1995 ... tant roles in mate-finding, predator avoidance, reduction of water loss, or the acquisition of food and other resources, yet ... aggregations and the availability of food, and that manipulating the position offood had no effect on the aggre- gations. ...... more quickly below the surface and into safety from rampant.

  2. Aggregate breakdown mechanisms as affected by soil texture and ...

    African Journals Online (AJOL)

    Soil samples with varying properties were collected from the surface 0–0.2 m from 14 ecotopes in Eastern Cape province. Aggregate stability was determined following the fast wetting (FW), slow wetting (SW) and wet stirring (WSt) methods. Soils with high quartz were the least stable due to its inability to bond with other clay ...

  3. Controlled release of estradiol solubilized in carbopol/surfactant aggregates.

    Science.gov (United States)

    Barreiro-Iglesias, Rafael; Alvarez-Lorenzo, Carmen; Concheiro, Angel

    2003-12-12

    The potential of carbopol/surfactant dispersions as solubilizing and controlled release systems of estradiol (a poorly water-soluble drug) was evaluated. The solubilization of estradiol in the dispersions of Carbopol 934 (0.25%) and Pluronic F-127, Tween 80, sodium dodecylsulfate (SDS), or benzalkonium chloride (BkCl) was assessed, by differential scanning calorimetry (DSC) of films obtained by desiccation, as a decrease in estradiol melting temperature and enthalpy. The amounts of estradiol solubilized in carbopol/SDS and carbopol/Tween 80 aqueous dispersions were considerably greater (solubilization capacity: 1.3 and 9 times greater) than in the surfactant alone solutions and up to 100 times greater than in water. High aggregates/water equilibrium partition coefficients of estradiol in carbopol/SDS (1768 M(-1)) and carbopol/Tween 80 (14114 M(-1)) dispersions were found. Carbopol/(1%) SDS/(25 mg/dl) estradiol and carbopol/(0.1%) Tween 80/(5 mg/dl) estradiol dispersions had a pH of around 4, were easy flowing, and showed sustained release for at least 1 week. Estradiol diffusion coefficients were greater when the receptor medium was 0.3-1.0% SDS solution than when it was iso-osmotic NaCl solution or pH 7.5 phosphate buffer. At this pH, a viscoelastic gel is formed on the donor side of the membrane and the drug diffusion slowed down. When the receptor medium contains a surfactant, estradiol release seems to happen as a direct exchange between the carbopol/surfactant aggregates and the receptor surfactant micelles. If no surfactant is in the receptor fluid, estradiol/surfactant complexes migrate towards the receptor. Despite the low viscosity of these dispersions, estradiol diffusion coefficients were in the same order of magnitude as those obtained with a commercially available neutralized ethanol/water carbopol gel of estradiol (60 mg/dl). When the receptor medium had no surfactant, the low affinity of estradiol for water prevented drug diffusion from the

  4. Evaluation of Different Mineral Filler Aggregates for Asphalt Mixtures

    Science.gov (United States)

    Wasilewska, Marta; Małaszkiewicz, Dorota; Ignatiuk, Natalia

    2017-10-01

    Mineral filler aggregates play an important role in asphalt mixtures because they fill voids in paving mix and improve the cohesion of asphalt binder. Limestone powder containing over 90% of CaCO3 is the most frequently used type of filler. Waste material from the production of coarse aggregate can be successfully used as a mineral filler aggregate for hot asphalt concrete mixtures as the limestone powder replacement. This paper presents the experimental results of selected properties of filler aggregates which were obtained from rocks with different mineral composition and origin. Five types of rocks were used as a source of the mineral filler aggregate: granite, gabbro, trachybasalt, quartz sandstone and rocks from postglacial deposits. Limestone filler was used in this study as the reference material. The following tests were performed: grading (air jet sieving), quality of fines according to methylene blue test, water content by drying in a ventilated oven, particle density using pyknometer method, Delta ring and ball test, Bitumen Number, fineness determined as Blaine specific surface area. Mineral filler aggregates showed significant differences when they were mixed with bitumen and stiffening effect in Delta ring and ball test was evaluated. The highest values were achieved when gabbro and granite fillers were used. Additionally, Scanning Electron Microscopy (SEM) analysis of grain shape and size was carried out. Significant differences in grain size and shape were observed. The highest non-homogeneity in size was determined for quartz sandstone, gabbro and granite filler. Their Blaine specific surface area was lower than 2800 cm2/g, while for limestone and postglacial fillers with regular and round grains it exceeded 3000 cm2/g. All examined mineral filler aggregates met requirements of Polish National Specification WT-1: 2014 and could be used in asphalt mixtures.

  5. Customer Aggregation: An Opportunity for Green Power?

    Energy Technology Data Exchange (ETDEWEB)

    Holt, E.; Bird, L.

    2001-02-26

    We undertook research into the experience of aggregation groups to determine whether customer aggregation offers an opportunity to bring green power choices to more customers. The objectives of this report, therefore, are to (1) identify the different types of aggregation that are occurring today, (2) learn whether aggregation offers an opportunity to advance sales of green power, and (3) share these concepts and approaches with potential aggregators and green power advocates.

  6. Development of a catalog of resilient modulus values for aggregate base for use with the mechanistic-empirical pavement design guide (MEPDG).

    Science.gov (United States)

    2015-06-01

    Base aggregate is one of the intermediate layers in a pavement system for both flexible and rigid surfaces. Characterization : of base aggregate is necessary for pavement thickness design. Many transportation agencies, including the Virginia Departme...

  7. SHAPE CHARACTERIZATION OF CONCRETE AGGREGATE

    Directory of Open Access Journals (Sweden)

    Jing Hu

    2011-05-01

    Full Text Available As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ is assumed to be different from the bulk material. In general, properties of conventional concrete have been found favoured by optimum packing density of the aggregate. Particle size is a common denominator in such studies. Size segregation in the ITZ among the binder particles in the fresh state, observed in simulation studies by concurrent algorithm-based SPACE system, additionally governs density as well as physical bonding capacity inside these shell-like zones around aggregate particles. These characteristics have been demonstrated qualitatively pertaining also after maturation of the concrete. Such properties of the ITZs have direct impact on composite properties. Despite experimental approaches revealed effects of aggregate grain shape on different features of material structure (among which density, and as a consequence on mechanical properties, it is still an underrated factor in laboratory studies, probably due to the general feeling that a suitable methodology for shape characterization is not available. A scientific argument hindering progress is the interconnected nature of size and shape. Presently, a practical problem preventing shape effects to be emphasized is the limitation of most computer simulation systems in concrete technology to spherical particles. New developments at Delft University of Technology will make it possible in the near future to generate jammed states, or other high-density fresh particle mixtures of non-spherical particles, which thereupon can be subjected to hydration algorithms. This paper will sketch the outlines of a methodological approach for shape assessment of loose (non-embedded aggregate grains, and demonstrate its use for two types of aggregate, allowing

  8. Contact-dependent carcinoma aggregate dispersion by M2a macrophages via ICAM-1 and β2 integrin interactions

    Science.gov (United States)

    Dang, Truong-Minh; Tu, Ting-Yuan; Leong Penny, Hwei-Xian; Wong, Siew-Cheng; Kamm, Roger D.; Thiery, Jean-Paul

    2015-01-01

    Tumor-associated macrophages (TAMs) can constitute up to 50% of the tumor mass and have strong implications in tumor progression and metastasis. Macrophages are plastic and can polarize to various subtypes that differ in terms of surface receptor expression as well as cytokine and chemokine production and effector function. Conventionally, macrophages are grouped into two major subtypes: the classically activated M1 macrophages and the alternatively activated M2 macrophages. M1 macrophages are pro-inflammatory, promote T helper (Th) 1 responses, and show tumoricidal activity, whereas M2 macrophages contribute to tissue repair and promote Th2 responses. Herein, we present a microfluidic system integrating tumor cell aggregates and subtypes of human monocyte-derived macrophages in a three-dimensional hydrogel scaffold, in close co-culture with an endothelial monolayer to create an in vitro tumor microenvironment. This platform was utilized to study the role of individual subtypes of macrophages (M0, M1, M2a, M2b and M2c) in human lung adenocarcinoma (A549) aggregate dispersion, as a representation of epithelial-mesenchymal transition (EMT). A significant difference was observed when M2a macrophages were in direct contact with or separated from A549 aggregates, suggesting a possible mechanism for proximity-induced, contact-dependent dissemination via ICAM-1 and integrin β2 interactions. Indeed, M2a macrophages tended to infiltrate and release cells from carcinoma cell aggregates. These findings may help in the development of immunotherapies based on enhancing the tumor-suppressive properties of TAMs. PMID:26231039

  9. Delayed inhibition of agonist-induced granulocyte-platelet aggregation after low-dose sevoflurane inhalation in humans.

    Science.gov (United States)

    Wacker, Johannes; Lucchinetti, Eliana; Jamnicki, Marina; Aguirre, José; Härter, Luc; Keel, Marius; Zaugg, Michael

    2008-06-01

    Sevoflurane can be used as sedative-analgesic drug with endothelial protective properties. We tested whether low-dose sevoflurane inhalation provides sustained inhibition of detrimental granulocyte-platelet aggregation in humans. Ten healthy male volunteers were enrolled in this crossover study. Each subject inhaled sevoflurane for 1 h at 0.5-1 vol % end-tidal concentration in oxygen (50 vol %). Inhaling oxygen (50 vol %) alone served as control. Venous blood samples were collected at baseline before inhalation, immediately after inhalation, and 24 h thereafter, and were used for flow cytometry to determine platelet surface marker (CD41, CD42b, CD62P/P-selectin, and PAC-1) on platelets and granulocytes and for kaolin-induced clot formation, as assessed by thromboelastography. In flow cytometry experiments, platelets were stimulated with arachidonic acid (AA, 30 microM), adenosine diphosphate (ADP, 1 microM), and thrombin receptor agonist peptide-6 (TRAP-6, 6 microM). AA, ADP, and TRAP-6 markedly increased the expression of CD62P on platelets, whereas CD42b (shedding) and PAC-1 (heterotypic conjugates) expression decreased. The amount of granulocyte-platelet aggregates increased upon agonist stimulation. Low-dose sevoflurane inhalation reduced ADP-induced CD62P expression on platelets 24 h after inhalation, and inhibited the formation of granulocyte-platelet aggregates under stimulation with AA and ADP after 1 and 24 h, and with TRAP-6 after 24 h compared with control. Inhibition of granulocyte-platelet aggregates was accompanied by reduced clot firmness 24 h after sevoflurane inhalation compared with control. We demonstrated for the first time that inhaling low-dose sevoflurane (<1 vol % end-tidal) inhibits agonist-induced granulocyte-platelet interactions 24 h after administration and thus counteracts thromboinflammatory processes.

  10. Identification and further characterization of the specific cell binding fragment from sponge aggregation factor

    OpenAIRE

    1986-01-01

    Monoclonal antibodies (McAbs) were raised against the aggregation factor (AF) from the marine sponge Geodia cydonium. Two clones were identified that secrete McAbs against the cell binding protein of the AF complex. Fab fragments of McAbs: 5D2-D11 completely abolished the activity of the AF to form secondary aggregates from single cells. The McAbs were determined to react with the AF in vitro; this interaction was prevented by addition of the aggregation receptor, isolated and purified from t...

  11. Platelet aggregates and ADP-induced platelet aggregation in ...

    African Journals Online (AJOL)

    Hypertension is a condition characterized by haemodynamic vascular stress and abnormal blood flow under high pressure and it is associated with complications that are, paradoxically, thrombotic rather than haemorrhagic. Spontaneous platelet aggregation has been known to be present in hypertension which predicts ...

  12. Environmentalism and natural aggregate mining

    Science.gov (United States)

    Drew, L.J.; Langer, W.H.; Sachs, J.S.

    2002-01-01

    Sustaining a developed economy and expanding a developing one require the use of large volumes of natural aggregate. Almost all human activity (commercial, recreational, or leisure) is transacted in or on facilities constructed from natural aggregate. In our urban and suburban worlds, we are almost totally dependent on supplies of water collected behind dams and transported through aqueducts made from concrete. Natural aggregate is essential to the facilities that produce energy-hydroelectric dams and coal-fired powerplants. Ironically, the utility created for mankind by the use of natural aggregate is rarely compared favorably with the environmental impacts of mining it. Instead, the empty quarries and pits are seen as large negative environmental consequences. At the root of this disassociation is the philosophy of environmentalism, which flavors our perceptions of the excavation, processing, and distribution of natural aggregate. The two end-member ideas in this philosophy are ecocentrism and anthropocentrism. Ecocentrism takes the position that the natural world is a organism whose arteries are the rivers-their flow must not be altered. The soil is another vital organ and must not be covered with concrete and asphalt. The motto of the ecocentrist is "man must live more lightly on the land." The anthropocentrist wants clean water and air and an uncluttered landscape for human use. Mining is allowed and even encouraged, but dust and noise from quarry and pit operations must be minimized. The large volume of truck traffic is viewed as a real menace to human life and should be regulated and isolated. The environmental problems that the producers of natural aggregate (crushed stone and sand and gravel) face today are mostly difficult social and political concerns associated with the large holes dug in the ground and the large volume of heavy truck traffic associated with quarry and pit operations. These concerns have increased in recent years as society's demand for

  13. Balancing energy flexibilities through aggregation

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Hose, Katja; Pedersen, Torben Bach

    2014-01-01

    in both energy production and consumption, is the key to solving these problems. Flexibilities can be expressed as flex-offers, which due to their high number need to be aggregated to reduce the complexity of energy scheduling. In this paper, we discuss balance aggregation techniques that already during......One of the main goals of recent developments in the Smart Grid area is to increase the use of renewable energy sources. These sources are characterized by energy fluctuations that might lead to energy imbalances and congestions in the electricity grid. Exploiting inherent flexibilities, which exist...

  14. A surface enhanced Raman scattering quantitative analytical platform for detection of trace Cu coupled the catalytic reaction and gold nanoparticle aggregation with label-free Victoria blue B molecular probe.

    Science.gov (United States)

    Li, Chongning; Ouyang, Huixiang; Tang, Xueping; Wen, Guiqing; Liang, Aihui; Jiang, Zhiliang

    2017-01-15

    With development of economy and society, there is an urgent need to develop convenient and sensitive methods for detection of Cu2+ pollution in water. In this article, a simple and sensitive SERS sensor was proposed to quantitative analysis of trace Cu2+ in water. The SERS sensor platform was prepared a common gold nanoparticle (AuNP)-SiO2 sol substrate platform by adsorbing HSA, coupling with the catalytic reaction of Cu2+-ascorbic acid (H2A)-dissolved oxygen, and using label-free Victoria blue B (VBB) as SERS molecular probes. The SERS sensor platform response to the AuNP aggregations by hydroxyl radicals (•OH) oxidizing from the Cu2+ catalytic reaction, which caused the SERS signal enhancement. Therefore, by monitoring the increase of SERS signal, Cu2+ in water can be determined accurately. The results show that the SERS sensor platforms owns a linear response with a range from 0.025 to 25μmol/L Cu2+, and with a detection limit of 0.008μmol/L. In addition, the SERS method demonstrated good specificity for Cu2+, which can determined accurately trace Cu2+ in water samples, and good recovery and accuracy are obtained for the water samples. With its high selectivity and good accuracy, the sensitive SERS quantitative analysis method is expected to be a promising candidate for determining copper ions in environmental monitoring and food safety. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Spreading and spontaneous motility of multicellular aggregates on soft substrates

    Science.gov (United States)

    Brochard-Wyart, Françoise

    2013-03-01

    We first describe the biomechanics of multicellular aggregates, a model system for tissues and tumors. We first characterize the tissue mechanical properties (surface tension, elasticity, viscosity) by a new pipette aspiration technique. The aggregate exhibits a viscoelastic response but, unlike an inert fluid, we observe aggregate reinforcement with pressure, which for a narrow range of pressures results in pulsed contractions or shivering. We interpret this reinforcement as a mechanosensitive active response of the acto-myosin cortex. Such an active behavior has previously been found to cause tissue pulsation during dorsal closure of Drosophila embryo. We then describe the spreading of aggregates on rigid glass substrates, varying both intercellular and substrate adhesion. We find both partial and complete wetting regimes. For the dynamics, we find a universal spreading law at short time, analogous to that of a viscoelastic drop. At long time, we observe, for strong substrate adhesion, a precursor film spreading around the aggregate. Depending on aggregate cohesion, this precursor film can be a dense cellular monolayer (liquid state) or consist of individual cells escaping from the aggregate body (gas state). The transition from liquid to gas state appears also to be present in the progression of a tumor from noninvasive to metastatic, known as the epithelial-mesenchymal transition. Finally, we describe the effect of the substrate rigidity on the phase diagram of wetting. On soft gels decorated with fibronectin and strongly cohesive aggregates, we have observed a wetting transition induced by the substrate rigidity: on ultra soft gels, below an elastic modulus Ec the aggregates do not spread, whereas above Ec we observe a precursor film expending with a diffusive law. The diffusion coefficient D(E) present a maximum for E =Em. A maximum of mobility versus the substrate rigidity had also been observed for single cells. Near Em, we observe a new phenomenon: a cell

  16. Chemoreception to aggregation pheromones in the common bed bug, Cimex lectularius.

    Science.gov (United States)

    Liu, Feng; Xiong, Caixing; Liu, Nannan

    2017-03-01

    The common bed bug, Cimex lectularius, is an obligate blood-feeding insect that is resurgent worldwide, posing a threat to human beings through its biting nuisance and disease transmission. Bed bug aggregation pheromone is considered a very promising attractant for use in the monitoring and management of bed bugs, but as yet little is known regarding the sensory physiology of bed bugs related to this pheromone. This study examined how the individual components of aggregation pheromone are perceived by the olfactory receptor neurons (ORNs) housed in different types of olfactory sensilla in bed bugs and the molecular basis for the ORNs' responses to the aggregation pheromone. We found that the ORNs in the D olfactory sensilla played a predominant role in detecting all the components of aggregation pheromone except for histamine, which was only recognized by the C sensilla. Bed bugs' E sensilla, which include four functionally distinct groups, showed only a very weak but variant sensitivity (both excitatory and inhibitory) to the components of aggregation pheromone. Functional tests of 15 odorant receptors (ORs) in response to the components of aggregation pheromone revealed that most of these components were encoded by multiple ORs with various tuning properties. This study provides a comprehensive understanding of how bed bug aggregation pheromone is perceived and recognized in the peripheral olfactory system and will contribute useful information to support the development of synthetic attractants for bed bug monitoring and control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Three cysteine residues of SLC52A1, a receptor for the porcine endogenous retrovirus-A (PERV-A), play a critical role in cell surface expression and infectivity.

    Science.gov (United States)

    Colon-Moran, Winston; Argaw, Takele; Wilson, Carolyn A

    2017-07-01

    Porcine endogenous retrovirus-A (PERV-A), a gammaretrovirus, infects human cells in vitro, thus raising the potential risk of cross-species transmission in xenotransplantation. Two members of the solute carrier family 52 (SLC52A1 and SLC52A2) are PERV-A receptors. Site-directed mutagenesis of the cDNA encoding SLC52A1 identified that only one of two putative glycosylation signals is occupied by glycans. In addition, we showed that glycosylation of SLC52A1 is not necessary for PERV-A receptor function. We also identified that at a minimum, three cysteine residues are sufficient for SLC52A1 cell surface expression. Mutation of cysteine at position 365 and either of the two cysteine residues in the C-terminal tail at positions 442 or 446 reduced SLC52A1 surface expression and PERV-A infection suggesting that these residues may contribute to overall structural stability and receptor function. Understanding interactions between PERV-A and its cellular receptor may provide novel strategies to prevent zoonotic infection in the setting of xenotransplantation. Published by Elsevier Inc.

  18. Mapping the energy and diffusion landscapes of membrane proteins at the cell surface using high-density single-molecule imaging and Bayesian inference: application to the multiscale dynamics of glycine receptors in the neuronal membrane.

    Science.gov (United States)

    Masson, Jean-Baptiste; Dionne, Patrice; Salvatico, Charlotte; Renner, Marianne; Specht, Christian G; Triller, Antoine; Dahan, Maxime

    2014-01-07

    Protein mobility is conventionally analyzed in terms of an effective diffusion. Yet, this description often fails to properly distinguish and evaluate the physical parameters (such as the membrane friction) and the biochemical interactions governing the motion. Here, we present a method combining high-density single-molecule imaging and statistical inference to separately map the diffusion and energy landscapes of membrane proteins across the cell surface at ~100 nm resolution (with acquisition of a few minutes). Upon applying these analytical tools to glycine neurotransmitter receptors at inhibitory synapses, we find that gephyrin scaffolds act as shallow energy traps (~3 kBT) for glycine neurotransmitter receptors, with a depth modulated by the biochemical properties of the receptor-gephyrin interaction loop. In turn, the inferred maps can be used to simulate the dynamics of proteins in the membrane, from the level of individual receptors to that of the population, and thereby, to model the stochastic fluctuations of physiological parameters (such as the number of receptors at synapses). Overall, our approach provides a powerful and comprehensive framework with which to analyze biochemical interactions in living cells and to decipher the multiscale dynamics of biomolecules in complex cellular environments. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Pyrene-Phosphonate Conjugate: Aggregation-Induced Enhanced Emission, and Selective Fe3+Ions Sensing Properties.

    Science.gov (United States)

    Padghan, Sachin D; Bhosale, Rajesh S; Bhosale, Sidhanath V; Antolasic, Frank; Al Kobaisi, Mohammad; Bhosale, Sheshanath V

    2017-08-29

    A new pyrene-phosphonate colorimetric receptor 1 has been designed and synthesized in a one-step process via amide bond formation between pyrene butyric acid chloride and phosphonate-appended aniline. The pyrene-phosphonate receptor 1 showed aggregation-induced enhanced emission (AIEE) properties in water/acetonitrile (ACN) solutions. Dynamic light scattering (DLS) characterization revealed that the aggregates of receptor 1 at 80% water fraction have an average size of ≈142 nm. Field emission scanning electron microscopy (FE-SEM) analysis confirmed the formation of spherical aggregates upon solvent evaporation. The sensing properties of receptor 1 were investigated by UV-vis, fluorescence emission spectroscopy, and other optical methods. Among the tested metal ions, receptor 1 is capable of recognizing the Fe 3+ ion selectively. The changes in spectral measurements were explained on the basis of complex formation. The composition of receptor 1 and Fe 3+ ions was determined by using Job's plot and found to be 1:1. The receptor 1 -Fe 3 + complex showed a reversible UV-vis response in the presence of EDTA.

  20. Mapping the topographic epitope landscape on the urokinase plasminogen activator receptor (uPAR by surface plasmon resonance and X-ray crystallography

    Directory of Open Access Journals (Sweden)

    Baoyu Zhao

    2015-12-01

    Full Text Available The urokinase-type plasminogen activator receptor (uPAR or CD87 is a glycolipid-anchored membrane protein often expressed in the microenvironment of invasive solid cancers and high levels are generally associated with poor patient prognosis (Kriegbaum et al., 2011 [1]. uPAR is organized as a dynamic modular protein structure composed of three homologous Ly6/uPAR domains (LU.This internally flexible protein structure of uPAR enables an allosteric regulation of the interactions with its two principal ligands: the serine protease urokinase-type plasminogen activator (uPA and the provisional matrix protein vitronectin (Vn (Mertens et al., 2012; Gårdsvoll et al., 2011; Madsen et al., 2007 [2–4]. The data presented here relates to the non-covalent trapping of one of these biologically relevant uPAR-conformations by a novel class of monoclonal antibodies (Zhao et al., 2015 [5] and to the general mapping of the topographic epitope landscape on uPAR. The methods required to achieve these data include: (1 recombinant expression and purification of a uPAR-hybrid protein trapped in the desired conformation [patent; WO 2013/020898 A12013]; (2 developing monoclonal antibodies with unique specificities using this protein as antigen; (3 mapping the functional epitope on uPAR for these mAbs by surface plasmon resonance with a complete library of purified single-site uPAR mutants (Zhao et al., 2015; Gårdsvoll et al., 2006 [5,6]; and finally (4 solving the three-dimensional structures for one of these mAbs by X-ray crystallography alone and in complex with uPAR [deposited in the PDB database as 4QTH and 4QTI, respectively].

  1. The combination of type I IFN, TNF-α, and cell surface receptor engagement with dendritic cells enables NK cells to overcome immune evasion by dengue virus.

    Science.gov (United States)

    Lim, Daniel Say Liang; Yawata, Nobuyo; Selva, Kevin John; Li, Na; Tsai, Chen Yu; Yeong, Lai Han; Liong, Ka Hang; Ooi, Eng Eong; Chong, Mun Keat; Ng, Mah Lee; Leo, Yee Sin; Yawata, Makoto; Wong, Soon Boon Justin

    2014-11-15

    Clinical studies have suggested the importance of the NK cell response against dengue virus (DenV), an arboviral infection that afflicts >50 million individuals each year. However, a comprehensive understanding of the NK cell response against dengue-infected cells is lacking. To characterize cell-contact mechanisms and soluble factors that contribute to the antidengue response, primary human NK cells were cocultured with autologous DenV-infected monocyte-derived dendritic cells (DC). NK cells responded by cytokine production and the lysis of target cells. Notably, in the absence of significant monokine production by DenV-infected DC, it was the combination of type I IFNs and TNF-α produced by DenV-infected DC that was important for stimulating the IFN-γ and cytotoxic responses of NK cells. Cell-bound factors enhanced NK cell IFN-γ production. In particular, reduced HLA class I expression was observed on DenV-infected DC, and IFN-γ production was enhanced in licensed/educated NK cell subsets. NK-DC cell contact was also identified as a requirement for a cytotoxic response, and there was evidence for both perforin/granzyme as well as Fas/Fas ligand-dependent pathways of killing by NK cells. In summary, our results have uncovered a previously unappreciated role for the combined effect of type I IFNs, TNF-α, and cell surface receptor-ligand interactions in triggering the antidengue response of primary human NK cells. Copyright © 2014 by The American Association of Immunologists, Inc.

  2. The cell surface glycoprotein CUB domain-containing protein 1 (CDCP1) contributes to epidermal growth factor receptor-mediated cell migration.

    Science.gov (United States)

    Dong, Ying; He, Yaowu; de Boer, Leonore; Stack, M Sharon; Lumley, John W; Clements, Judith A; Hooper, John D

    2012-03-23

    Epidermal growth factor (EGF) activation of the EGF receptor (EGFR) is an important mediator of cell migration, and aberrant signaling via this system promotes a number of malignancies including ovarian cancer. We have identified the cell surface glycoprotein CDCP1 as a key regulator of EGF/EGFR-induced cell migration. We show that signaling via EGF/EGFR induces migration of ovarian cancer Caov3 and OVCA420 cells with concomitant up-regulation of CDCP1 mRNA and protein. Consistent with a role in cell migration CDCP1 relocates from cell-cell junctions to punctate structures on filopodia after activation of EGFR. Significantly, disruption of CDCP1 either by silencing or the use of a function blocking antibody efficiently reduces EGF/EGFR-induced cell migration of Caov3 and OVCA420 cells. We also show that up-regulation of CDCP1 is inhibited by pharmacological agents blocking ERK but not Src signaling, indicating that the RAS/RAF/MEK/ERK pathway is required downstream of EGF/EGFR to induce increased expression of CDCP1. Our immunohistochemical analysis of benign, primary, and metastatic serous epithelial ovarian tumors demonstrates that CDCP1 is expressed during progression of this cancer. These data highlight a novel role for CDCP1 in EGF/EGFR-induced cell migration and indicate that targeting of CDCP1 may be a rational approach to inhibit progression of cancers driven by EGFR signaling including those resistant to anti-EGFR drugs because of activating mutations in the RAS/RAF/MEK/ERK pathway.

  3. Correlation of Surface Toll-Like Receptor 9 Expression with IL-17 Production in Neutrophils during Septic Peritonitis in Mice Induced by E. coli

    Science.gov (United States)

    Ren, Yunjia; Hao, Xu; Zhao, Peiyan; Yu, Yongli; Wang, Liying

    2016-01-01

    IL-17 is a proinflammatory cytokine produced by various immune cells. Polymorphonuclear neutrophils (PMNs) are the first line of defense in bacterial infection and express surface Toll-like receptor 9 (sTLR9). To study the relationship of sTLR9 and IL-17 in PMNs during bacterial infection, we infected mice with E. coli intraperitoneally to establish a septic peritonitis model for studying the PMNs response in peritoneal cavity. We found that PMNs and some of “giant cells” were massively accumulated in the peritoneal cavity of mice with fatal septic peritonitis induced by E. coli. Kinetically, the CD11b+ PMNs were increased from 20–40% at 18 hours to >80% at 72 hours after infection. After E. coli infection, sTLR9 expression on CD11b+ and CD11b− PMNs and macrophages in the PLCs were increased at early stage and deceased at late stage; IL-17 expression was also increased in CD11b+ PMNs, CD11b− PMNs, macrophages, and CD3+ T cells. Using experiments of in vitro blockage, qRT-PCR and cell sorting, we confirmed that PMNs in the PLCs did increase their IL-17 expression during E. coli infection. Interestingly, sTLR9−CD11b+Ly6G+ PMNs, not sTLR9+CD11b+Ly6G+ PMNs, were found to be able to increase their IL-17 expression. Together, the data may help understand novel roles of PMNs in septic peritonitis. PMID:27057095

  4. Retention of ferrofluid aggregates at the target site during magnetic drug targeting

    Energy Technology Data Exchange (ETDEWEB)

    Asfer, Mohammed, E-mail: asfer786@gmail.com [School of Engineering and Technology, BML Munjal University, Haryana (India); Saroj, Sunil Kumar [Department of Mechanical Engineering, IIT Kanpur, Kanpur (India); Panigrahi, Pradipta Kumar, E-mail: panig@iitk.ac.in [Department of Mechanical Engineering, IIT Kanpur, Kanpur (India)

    2017-08-15

    Highlights: • The present in vitro work reports the retention dynamics of ferrofluid aggregates at the target site against a bulk flow of DI water inside a micro capillary during magnetic drug targeting. • The recirculation zone at the downstream of the aggregate is found to be a function of aggregate height, Reynolds number and the degree of surface roughness of the outer boundary of the aggregate. • The reported results of the present work can be used as a guideline for the better design of MDT technique for in vivo applications. - Abstract: The present study reports the retention dynamics of a ferrofluid aggregate localized at the target site inside a glass capillary (500 × 500 µm{sup 2} square cross section) against a bulk flow of DI water (Re = 0.16 and 0.016) during the process of magnetic drug targeting (MDT). The dispersion dynamics of iron oxide nanoparticles (IONPs) into bulk flow for different initial size of aggregate at the target site is reported using the brightfield visualization technique. The flow field around the aggregate during the retention is evaluated using the µPIV technique. IONPs at the outer boundary experience a higher shear force as compared to the magnetic force, resulting in dispersion of IONPs into the bulk flow downstream to the aggregate. The blockage effect and the roughness of the outer boundary of the aggregate resulting from chain like clustering of IONPs contribute to the flow recirculation at the downstream region of the aggregate. The entrapment of seeding particles inside the chain like clusters of IONPs at the outer boundary of the aggregate reduces the degree of roughness resulting in a streamlined aggregate at the target site at later time. The effect of blockage, structure of the aggregate, and disturbed flow such as recirculation around the aggregate are the primary factors, which must be investigated for the effectiveness of the MDT process for in vivo applications.

  5. Allelic Polymorphism Determines Surface Expression or Intracellular Retention of the Human NK Cell Receptor KIR2DL5A (CD158f)

    Science.gov (United States)

    Cisneros, Elisa; Estefanía, Ernesto; Vilches, Carlos

    2017-01-01

    KIR2DL5 (CD158f) is the most recently identified inhibitory member of human killer-cell Ig-like receptors (KIRs), which enable NK cells to sense self-HLA. Unlike KIR2DL1–3, recognizing HLA-C allotypes through Ig-like domains of the D1–D2 type, KIR2DL5 shares a D0–D2 configuration with KIR2DL4, and its ligands have not been identified. KIR2DL5 is encoded by two paralogous genes displaying copy number variation and allelic polymorphism—KIR2DL5A and KIR2DL5B. UP-R1 mAb, raised against the common allele KIR2DL5A*001, enables specific KIR2DL5 detection. However, not every KIR2DL5+ individual has NK cells staining with UP-R1, discrepancy explained in part by epigenetically silent KIR2DL5B alleles with a distinctive substitution in a promoter RUNX-binding site. Furthermore, we show here that the transcribed allele KIR2DL5A*005, second most common of its locus, fails to confer NK cells UP-R1 reactivity, phenotype explained by inefficacious transport of its product to the cell surface. Two amino acid substitutions distinguish the KIR2DL5A*005 and *001 coding regions. Western blot, flow cytometry, and confocal microscopy analyses of cells transfected with tagged constructs demonstrate that a serine substitution for glycine-174, conserved in most KIR, is mainly responsible for KIR2DL5A*005 intracellular retention, and it also affects mAb recognition. In contrast, substitution of aspartate for asparagine 152 has only a minor effect on surface expression, despite destroying an otherwise conserved N-glycosylation site. Our results help to explain the variable expression profile of KIR2DL5+ subjects and indicate that functional polymorphisms in both its promoter and its coding regions are critical for understanding the KIR2DL5 role in immunity and its importance for human health. PMID:28144240

  6. Do chemical gradients within soil aggregates reflect plant/soil interactions?

    Science.gov (United States)

    Krüger, Jaane; Hallas, Till; Kinsch, Lena; Stahr, Simon; Prietzel, Jörg; Lang, Friederike

    2016-04-01

    As roots and hyphae often accumulate at the surface of soil aggregates, their formation and turnover might be related to the bioavailability especially of immobile nutrients like phosphorus. Several methods have been developed to obtain specific samples from aggregate surfaces and aggregate cores and thus to investigate differences between aggregate shell and core. However, these methods are often complex and time-consuming; therefore most common methods of soil analysis neglect the distribution of nutrients within aggregates and yield bulk soil concentrations. We developed a new sequential aggregate peeling method to analyze the distribution of different nutrients within soil aggregates (4-20 mm) from four forest sites (Germany) differing in concentrations of easily available mineral P. Aggregates from three soil depths (Ah, BwAh, Bw) were isolated, air-dried, and peeled with a sieving machine performing four sieving levels with increasing sieving intensity. This procedure was repeated in quadruplicate, and fractions of the same sample and sieving level were pooled. Carbon and N concentration, citric acid-extractable PO4 and P, as well as total element concentrations (P, K, Mg, Ca, Al, Fe) were analyzed. Additionally, synchrotron-based P K-edge XANES spectroscopy was applied on selected samples to detect P speciation changes within the aggregates. The results reveal for most samples a significantly higher C and N concentration at the surface compared to the interior of the aggregates. Carbon and N gradients get more pronounced with increasing soil depth and decreasing P status of study sites. This might be explained by lower aggregate turnover rates of subsoil horizons and intense bioturbation on P-rich sites. This assumption is also confirmed by concentrations of citric acid-extractable PO4 and P: gradients within aggregates are getting more pronounced with increasing soil depth and decreasing P status. However, the direction of these gradients is site

  7. Plexcitonic nanoparticles: plasmon-exciton coupling in nanoshell-J-aggregate complexes.

    Science.gov (United States)

    Fofang, Nche T; Park, Tae-Ho; Neumann, Oara; Mirin, Nikolay A; Nordlander, Peter; Halas, Naomi J

    2008-10-01

    Stable Au nanoshell-J-aggregate complexes are formed that exhibit coherent coupling between the localized plasmons of a nanoshell and the excitons of molecular J-aggregates adsorbed on its surface. By tuning the nanoshell plasmon energies across the exciton line of the J-aggregate, plasmon-exciton coupling energies for these complexes are obtained. The strength of this interaction is dependent on the specific plasmon mode of the nanoparticle coupled to the J-aggregate exciton. From a model based on Gans theory, we obtain an expression for the plasmon-exciton hybridized states of the complex.

  8. Determination of aggregation thresholds of UV absorbing anionic surfactants by frontal analysis continuous capillary electrophoresis.

    Science.gov (United States)

    Le Saux, Thomas; Varenne, Anne; Gareil, Pierre

    2004-06-04

    Aggregation of anionic surfactants was investigated by frontal analysis continuous capillary electrophoresis (FACCE), a method involving the continuous electrokinetic introduction of the surfactant sample into the separation capillary. This process results in a partial separation of the monomeric and aggregated forms without perturbing the monomer-aggregate equilibrium. The critical micelle concentration (CMC) can then be easily derived from the height of the firstly detected migration front, corresponding to the monomeric form. This approach is exemplified with octyl and dodecylbenzenesulfonates and compared with conductimetry and surface tension measurements. FACCE turns out to be an effective method for the determination of CMC and intermediate aggregation phenomena with very small sample and short time requirements.

  9. Sea Dredged Gravel versus Crushed Granite as Coarse Aggregate for Self Compacting Concrete in Aggressive Environment

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.; Kristensen, Lasse Frølich

    2007-01-01

    Properties of self compacting concrete (SCC) with two types of coarse aggregate - sea dredged gravel with smooth and rounded particles and crushed granite with rough and angular particles - have been studied. Sea gravel allowed a higher aggregate proportion in the concrete leading to a higher...... modulus of elasticity. Tensile and compressive strength were found to depend both on aggregate type and on the properties of the interfacial zone close to the aggregate surface. Freeze-thaw scaling resistance was good with crushed granite, whereas sea gravel led to more severe scaling caused by porphyry...

  10. Shape characterization of concrete aggregate

    NARCIS (Netherlands)

    Stroeven, P.; Hu, J.

    2006-01-01

    As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ) is assumed to be different from the bulk material. In

  11. POLYAMINES IN MODULATING PROTEIN AGGREGATION

    Directory of Open Access Journals (Sweden)

    Rimpy K. Chowhan

    2012-12-01

    Full Text Available Polyamines are ubiquitous aliphatic polycations with multiple molecular and cellular functions. They were first indentified by Leeuwenhoek in 1678. Since then many investigations had been done to understand the physiological significance of these molecules. Being cationic at physiologic pH, they interact with various biomolecules including DNA, RNA, proteins, and help in many cellular functions. Apart from their vast number of physiological functions, they are also implicated in modulation of protein aggregation or amyloid formation. It is now important to combine and analyze all of the findings on polyamine-induced aggregation, come to a conclusion, and relate the phenomenon of this protein aggregation to the physiology of the cellular function. Through this review, we had tried to cover almost all the investigations that had been done to-date, to explore the roles of polyamines in aggregation of various proteins. We have also incorporated future research avenues that might be of interest to many cellular biologist and protein chemists.

  12. Diversity, intent, and aggregated search

    NARCIS (Netherlands)

    de Rijke, M.

    2014-01-01

    Diversity, intent and aggregated search are three core retrieval concepts that receive significant attention. In search result diversification one typically considers the relevance of a document in light of other retrieved documents. The goal is to identify the probable "aspects" of an ambiguous

  13. Aggregation Methods in Food Chains.

    NARCIS (Netherlands)

    Kooi, B.W.; Poggiale, J.C.; Auger, P.

    1998-01-01

    The aim of this paper is to apply aggregation methods to food chains under batch and chemostat conditions. These predator-prey systems are modelled using ODEs, one for each trophic level. Because the models are based on mass conservation laws, they are conservative and this allows perfect

  14. Excitons in tubular molecular aggregates

    NARCIS (Netherlands)

    Didraga, C; Knoester, J

    2004-01-01

    We present a brief overview of recent work on the optical properties of molecular aggregates with a tubular (cylindrical) shape. The exciton states responsible for these properties can be distinguished with regard to a transverse wave number, which directly relates to optical selection rules and

  15. Aggregating and Disaggregating Flexibility Objects

    DEFF Research Database (Denmark)

    Siksnys, Laurynas; Valsomatzis, Emmanouil; Hose, Katja

    2015-01-01

    of such objects while preserving flexibility. Hence, this paper formally defines the concept of flexibility objects (flex-objects) and provides a novel and efficient solution for aggregating and disaggregating flex-objects. Out of the broad range of possible applications, this paper will focus on smart grid...... the energy domain show that the proposed solutions provide good performance while satisfying the strict requirements....

  16. Studies on recycled aggregates-based concrete.

    Science.gov (United States)

    Rakshvir, Major; Barai, Sudhirkumar V

    2006-06-01

    Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design.

  17. Influence of caffeine on blood pressure and platelet aggregation

    Directory of Open Access Journals (Sweden)

    José Wilson S. Cavalcante

    2000-08-01

    Full Text Available OBJECTIVE: Studies have demonstrated that methylxanthines, such as caffeine, are A1 and A2 adenosine receptor antagonists found in the brain, heart, lungs, peripheral vessels, and platelets. Considering the high consumption of products with caffeine in their composition, in Brazil and throughout the rest of the world, the authors proposed to observe the effects of this substance on blood pressure and platelet aggregation. METHODS: Thirteen young adults, ranging from 21 to 27 years of age, participated in this study. Each individual took 750mg/day of caffeine (250mg tid, over a period of seven days. The effects on blood pressure were analyzed through the pressor test with handgrip, and platelet aggregation was analyzed using adenosine diphosphate, collagen, and adrenaline. RESULTS: Diastolic pressure showed a significant increase 24 hours after the first intake (p<0.05. This effect, however, disappeared in the subsequent days. The platelet aggregation tests did not reveal statistically significant alterations, at any time during the study. CONCLUSION: The data suggest that caffeine increases diastolic blood pressure at the beginning of caffeine intake. This hypertensive effect disappears with chronic use. The absence of alterations in platelet aggregation indicates the need for larger randomized studies.

  18. Sustained increase in platelet aggregation after the cessation of clopidogrel.

    Science.gov (United States)

    Djukanovic, Nina; Todorovic, Zoran; Zamaklar-Trifunovic, Danijela; Protic, Dragana; Dzudovic, Boris; Ostojic, Miodrag; Obradovic, Slobodan

    2016-02-01

    This study shows that the abrupt cessation of one-year clopidogrel treatment was not associated with thrombotic events in a prospective, multicentre study that enrolled 200 patients subjected to coronary stent implantation and treated with aspirin + clopidogrel 1 year after the stent placement. The aim of the study was to investigate the causes of a sustained increase of platelet aggregability, considering that the values of platelet aggregation stimulated with ADP + PGE1 (ADPHS values) significantly increased 10-90 days after the cessation of clopidogrel. Values of platelet aggregation induced by thrombin receptor activating peptide (TRAP values) and arachidonic acid (ASPI values) were divided into quartiles on the basis of ADPHS values 10 days after stopping clopidogrel (ADPHS10 ). There was a significant difference between TRAP values divided into quartiles according to ADPHS10 , 10, 45 and 90 days after stopping clopidogrel (P clopidogrel (P = 0.028 and 0.003). The results of the study indicate that patients with early pronounced rebound phenomena to clopidogrel termination have a long-term (at least 90 days) increased platelet aggregation to other agonists such as thrombin-related activated protein and arachidonic acid, suggesting the complex mutual relationship of various factors/agonists influencing the function of platelets. © 2016 John Wiley & Sons Australia, Ltd.

  19. The Neuroprotective Peptide Poly-Arginine-12 (R12) Reduces Cell Surface Levels of NMDA NR2B Receptor Subunit in Cortical Neurons; Investigation into the Involvement of Endocytic Mechanisms.

    Science.gov (United States)

    MacDougall, Gabriella; Anderton, Ryan S; Edwards, Adam B; Knuckey, Neville W; Meloni, Bruno P

    2017-02-01

    We have previously reported that cationic poly-arginine and arginine-rich cell-penetrating peptides display high-level neuroprotection and reduce calcium influx following in vitro excitotoxicity, as well as reduce brain injury in animal stroke models. Using the neuroprotective peptides poly-arginine R12 (R12) and the NR2B9c peptide fused to the arginine-rich carrier peptide TAT (TAT-NR2B9c; also known as NA-1), we investigated the mechanisms whereby poly-arginine and arginine-rich peptides reduce glutamate-induced excitotoxic calcium influx. Using cell surface biotin protein labeling and western blot analysis, we demonstrated that R12 and TAT-NR2B9c significantly reduced cortical neuronal cell surface expression of the NMDA receptor subunit NR2B. Chemical endocytic inhibitors used individually or in combination prior to glutamate excitotoxicity did not significantly affect R12 peptide neuroprotective efficacy. Similarly, pretreatment of neurons with enzymes to degrade anionic cell surface proteoglycans, heparan sulfate proteoglycan (HSPG), and chondroitin sulfate proteoglycan (CSPG), as well as sialic acid residues, did not significantly affect peptide neuroprotective efficacy. While the exact mechanisms responsible for R12 peptide-mediated NMDA receptor NR2B subunit cell surface downregulation were not identified, an endocytic process could not be ruled out. The study supports our hypothesis that arginine-rich peptides reduce excitotoxic calcium influx by reducing the levels of cell surface ion channels.

  20. Engineering Behavior of Concrete with Recycled Aggregate

    Directory of Open Access Journals (Sweden)

    Ayob Afizah

    2017-01-01

    Full Text Available Concrete is extensively used as construction materials in Malaysia. Concrete contributes suitable feature for construction industry for instance durability, adequate compressive strength, fire resistance, availability and is economic as compared to other construction materials. Depletion of natural resources and disposal of construction and demolition waste remarkably claim environmental threat. In this paper, the engineering behavior, durability, and concrete microstructure of recycled concrete aggregates (RCA on short-term concrete properties were investigated. The studied concrete at design mix proportion of 1:0.55:2.14:2.61 (weight of cement :coarse aggregates :sand :water used to obtain medium-high compressive strength with 20%, 50%, and 100% of RCA. Results show that for the same water/cement ratio, RCA replacement up to 50% still achieved the targeted compressive strength of 25 MPa at 28 curing days. Addition, at similar RCA replacement, the highest carbonation depth value was found at 1.03 mm which could be attributed to the pozzolanic reaction, thus led to lower carbonation resistance. Scanning electron microscopy microstructure shows that the RCA surface was porous and covered with loose particles. Moreover, the interfacial transition zone was composed of numerous small pores, micro cracks, and fissures that surround the mortar matrix. On the basis of the obtained results, recommendable mineral admixtures of RCA are necessary to enhance the quality of concrete construction.

  1. Defining and Systematic Analyses of Aggregation Indices to Evaluate Degree of Calcium Oxalate Crystal Aggregation

    Directory of Open Access Journals (Sweden)

    Sakdithep Chaiyarit

    2017-12-01

    Full Text Available Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM crystals with various concentrations (25–800 μg/ml in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant. The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r = 0.997; p < 0.001, whereas the equally second rank included aggregated mass index and optical density (r = 0.993; p < 0.001 and r = −0.993; p < 0.001, respectively and the equally forth were aggregation coefficient and span (r = 0.991; p < 0.001 for both. These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

  2. Defining and Systematic Analyses of Aggregation Indices to Evaluate Degree of Calcium Oxalate Crystal Aggregation.

    Science.gov (United States)

    Chaiyarit, Sakdithep; Thongboonkerd, Visith

    2017-01-01

    Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM) crystals with various concentrations (25-800 μg/ml) in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant). The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r = 0.997; p < 0.001), whereas the equally second rank included aggregated mass index and optical density (r = 0.993; p < 0.001 and r = -0.993; p < 0.001, respectively) and the equally forth were aggregation coefficient and span (r = 0.991; p < 0.001 for both). These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

  3. Marine snow microbial communities: scaling of abundances with aggregate size

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2003-01-01

    Marine aggregates are inhabited by diverse microbial communities, and the concentration of attached microbes typically exceeds concentrations in the ambient water by orders of magnitude. An extension of the classical Lotka-Volterra model, which includes 3 trophic levels (bacteria, flagellates......, ciliates) and considers colonization, detachment, growth and predator-prey interactions on the surface of the particle, was used to examine the processes that govern abundances of attached micro-organisms. Effects of sinking on colonization rates as well as the fractal nature of natural aggregates were...... also taken into account. As input for the model, I used experimentally determined encounter and detachment rates, and density-dependent growth and grazing rates, as well as information on relevant properties of natural aggregates, all taken from the literature. The model reproduces the temporal...

  4. Epicuticular lipids induce aggregation in Chagas disease vectors

    Directory of Open Access Journals (Sweden)

    Juárez M Patricia

    2009-01-01

    Full Text Available Abstract Background The triatomine bugs are vectors of the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease. Aggregation behavior plays an important role in their survival by facilitating the location of refuges and cohesion of aggregates, helping to keep them safely assembled into shelters during daylight time, when they are vulnerable to predators. There are evidences that aggregation is mediated by thigmotaxis, by volatile cues from their faeces, and by hexane-extractable contact chemoreceptive signals from their cuticle surface. The epicuticular lipids of Triatoma infestans include a complex mixture of hydrocarbons, free and esterified fatty acids, alcohols, and sterols. Results We analyzed the response of T. infestans fifth instar nymphs after exposure to different amounts either of total epicuticular lipid extracts or individual lipid fractions. Assays were performed in a circular arena, employing a binary choice test with filter papers acting as aggregation attractive sites; papers were either impregnated with a hexane-extract of the total lipids, or lipid fraction; or with the solvent. Insects were significantly aggregated around papers impregnated with the epicuticular lipid extracts. Among the lipid fractions separately tested, only the free fatty acid fraction promoted significant bug aggregation. We also investigated the response to different amounts of selected fatty acid components of this fraction; receptiveness varied with the fatty acid chain length. No response was elicited by hexadecanoic acid (C16:0, the major fatty acid component. Octadecanoic acid (C18:0 showed a significant assembling effect in the concentration range tested (0.1 to 2 insect equivalents. The very long chain hexacosanoic acid (C26:0 was significantly attractant at low doses (≤ 1 equivalent, although a repellent effect was observed at higher doses. Conclusion The detection of contact aggregation pheromones has practical

  5. Epicuticular lipids induce aggregation in Chagas disease vectors.

    Science.gov (United States)

    Figueiras, Alicia N Lorenzo; Girotti, Juan R; Mijailovsky, Sergio J; Juárez, M Patricia

    2009-01-27

    The triatomine bugs are vectors of the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease. Aggregation behavior plays an important role in their survival by facilitating the location of refuges and cohesion of aggregates, helping to keep them safely assembled into shelters during daylight time, when they are vulnerable to predators. There are evidences that aggregation is mediated by thigmotaxis, by volatile cues from their faeces, and by hexane-extractable contact chemoreceptive signals from their cuticle surface. The epicuticular lipids of Triatoma infestans include a complex mixture of hydrocarbons, free and esterified fatty acids, alcohols, and sterols. We analyzed the response of T. infestans fifth instar nymphs after exposure to different amounts either of total epicuticular lipid extracts or individual lipid fractions. Assays were performed in a circular arena, employing a binary choice test with filter papers acting as aggregation attractive sites; papers were either impregnated with a hexane-extract of the total lipids, or lipid fraction; or with the solvent. Insects were significantly aggregated around papers impregnated with the epicuticular lipid extracts. Among the lipid fractions separately tested, only the free fatty acid fraction promoted significant bug aggregation. We also investigated the response to different amounts of selected fatty acid components of this fraction; receptiveness varied with the fatty acid chain length. No response was elicited by hexadecanoic acid (C16:0), the major fatty acid component. Octadecanoic acid (C18:0) showed a significant assembling effect in the concentration range tested (0.1 to 2 insect equivalents). The very long chain hexacosanoic acid (C26:0) was significantly attractant at low doses (higher doses. The detection of contact aggregation pheromones has practical application in Chagas disease vector control. These data may be used to help design new tools against triatomine bugs.

  6. The best of shape: 3-D scanning in South Africa gives aggregate a closer look

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2011-09-01

    Full Text Available The author of this article is conducting research in South Africa which addresses the difficulties in pavement design in developing methods and procedures for accurate quantification of aggregate shape and surface properties, which are well known...

  7. Fractal dimensions and porosities of Zoogloea ramigera and Saccharomyces cerevisae aggregates.

    Science.gov (United States)

    Logan, B E; Wilkinson, D B

    1991-08-05

    The fractal nature microbial aggregates is a function of the type of microorganism and mixing conditions used to develop aggregates. We determined fractal dimensions from length-projected area (D(2)) and length-number scaling (D(3)) relationships. Aggregates of Zoogloea ramigera developed in rotating test tubes were both surface and mass fractals, with fractal dimensions of D(2) = 1.69 +/- 0.11 and D(3)= 1.79 +/- 0.28 (+/-standard deviation), respectively. When we grew this bacteria in a bench-top fermentor, aggregates maintained their surface fractal characteristics (D(2) = 1.78 +/- 0.11) but lost their mass fractal characteristics (D(3) = 2.99 +/- 0.36). Yeast aggregates (Saccharomyces cerevisae) grown in rotating tests tubes had higher average fractal dimensions than bacterial aggregates grown under physically identical conditions, and were also considered fractal (D(2) = 1.92 +/- 0.08 and D(3) = 2.66 +/- 0.34). Aggregates porosity can be expressed in term of a fractal dimensions, but average porosities are higher than expected. The porosities of yeast aggregates (0.9250-0.9966) were similar to porosities of bacterial aggregates (0.9250-0.9966) cultured under the same physical conditions, although bacterial aggregates developed in the reactor had higher average porosities (0.9857-0.9980). These results suggest that that scaling relationships based on fractal geometry may be more useful than equations derived from Euclidean geometry for quantifying the effects of different fluid mechanical environments on aggregates morphology and characteristics such as density, porosity, and projected surface area.

  8. INVESTIGATION OF SKID RESISTANCE PROPERTIES OF AGGREGATES USED IN AFYONKARAHISAR CITY PAVEMENTS

    Directory of Open Access Journals (Sweden)

    Cahit GÜRER

    2007-02-01

    Full Text Available For a safe driving, pavement surface aggregates must have superior physical and mechanical properties. Although high rate of accidents is mainly due to drivers errors, pavement surface properties affect significantly occurance of traffic accidents. The most important factor in the highways leading to traffic accidents are the skid resistance. In this study, adherence test with Vialit plate, Nicholson stripping test, accelerated polishing test (PSV were carried out on four aggregate samples which were used in seal coats and hot mix asphalt in Afyonkarahisar City. Results were compared with values of specification limits. The results showed that particularly limestone aggregates polishing stone values are poorer than volcanic aggregates sample. Especially, use of aggregates having a good polishing resistance, will be an important factor increasing driving safety.

  9. DYRK1A-mediated phosphorylation of GluN2A at Ser1048 regulates the surface expression and channel activity of GluN1/GluN2A receptors

    Directory of Open Access Journals (Sweden)

    Cristina eGrau

    2014-10-01

    Full Text Available N-methyl-D-aspartate glutamate receptors (NMDARs play a pivotal role in neural development and synaptic plasticity, as well as in neurological disease. Since NMDARs exert their function at the cell surface, their density in the plasma membrane is finely tuned by a plethora of molecules that regulate their production, trafficking, docking and internalization in response to external stimuli. In addition to transcriptional regulation, the density of NMDARs is also influenced by post-translational mechanisms like phosphorylation, a modification that also affects their biophysical properties. We previously described the increased surface expression of GluN1/GluN2A receptors in transgenic mice overexpressing the Dual specificity tyrosine-phosphorylation-regulated kinase 1A (DYRK1A, suggesting that DYRK1A regulates NMDARs. Here we have further investigated whether the density and activity of NMDARs was modulated by DYRK1A phosphorylation. Accordingly, we show that endogenous DYRK1A is recruited to GluN2A-containing NMDARs in the adult mouse brain, and we identify a DYRK1A phosphorylation site at Ser1048 of GluN2A, within its intracellular C-terminal domain. Mechanistically, the DYRK1A-dependent phosphorylation of GluN2A at Ser1048 hinders the internalization of GluN1/GluN2A, causing an increase of surface GluN1/GluN2A in heterologous systems, as well as in primary cortical neurons. Furthermore, GluN2A phosphorylation at Ser1048 increases the current density and potentiates the gating of GluN1/GluN2A receptors. We conclude that DYRK1A is a direct regulator of NMDA receptors and we propose a novel mechanism for the control of NMDAR activity in neurons.

  10. Hail formation triggers rapid ash aggregation in volcanic plumes.

    Science.gov (United States)

    Van Eaton, Alexa R; Mastin, Larry G; Herzog, Michael; Schwaiger, Hans F; Schneider, David J; Wallace, Kristi L; Clarke, Amanda B

    2015-08-03

    During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterized 'wet' eruption. The 2009 eruption of Redoubt Volcano, Alaska, incorporated water from the surface (in this case, a glacier), which is a common occurrence during explosive volcanism worldwide. Observations from C-band weather radar, fall deposits and numerical modelling demonstrate that hail-forming processes in the eruption plume triggered aggregation of ∼95% of the fine ash and stripped much of the erupted mass out of the atmosphere within 30 min. Based on these findings, we propose a mechanism of hail-like ash aggregation that contributes to the anomalously rapid fallout of fine ash and occurrence of concentrically layered aggregates in volcanic deposits.

  11. Role of Multicellular Aggregates in Biofilm Formation

    National Research Council Canada - National Science Library

    Kragh, Kasper N; Hutchison, Jaime B; Melaugh, Gavin; Rodesney, Chris; Roberts, Aled E L; Irie, Yasuhiko; Jensen, Peter Ø; Diggle, Stephen P; Allen, Rosalind J; Gordon, Vernita; Bjarnsholt, Thomas

    2016-01-01

    .... However, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process...

  12. Recycled concrete aggregate in portland cement concrete.

    Science.gov (United States)

    2013-01-01

    Aggregates can be produced by crushing hydraulic cement concrete and are known as recycled concrete : aggregates (RCA). This report provides results from a New Jersey Department of Transportation study to identify : barriers to the use of RCA in new ...

  13. Partially clairvoyant scheduling for aggregate constraints

    Directory of Open Access Journals (Sweden)

    K. Subramani

    2005-01-01

    constraints. In this paper, we extend the class of constraints for which partially clairvoyant schedules can be determined efficiently, to include aggregate constraints. Aggregate constraints form a strict superset of standard constraints and can be used to model performance metrics.

  14. Sea-urchin-like Au nanocluster with surface-enhanced raman scattering in detecting epidermal growth factor receptor (EGFR) mutation status of malignant pleural effusion.

    Science.gov (United States)

    Wang, Lei; Guo, Ting; Lu, Qiang; Yan, Xiaolong; Zhong, Daixing; Zhang, Zhipei; Ni, Yunfeng; Han, Yong; Cui, Daxiang; Li, Xiaofei; Huang, Lijun

    2015-01-14

    Somatic mutations in the epidermal growth factor receptor (EGFR) gene are common in patients with lung adenocarcinomas and are associated with sensitivity to the small-molecule tyrosine kinase inhibitors (TKIs). For 10%-50% of the patients who experienced malignant pleural effusion (MPE), pathological diagnosis might rely exclusively on finding lung cancer cells in the MPE. Current methods based on polymerase chain reaction were utilized to test EGFR mutation status of MPE samples, but the accuracy of the test data was very low, resulting in many patients losing the chance of TKIs treatment. Herein, we synthesized the sea-urchin-like Au nanocluster (AuNC) with an average diameter of 92.4 nm, composed of 15-nm nanopricks. By introducing abunda