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Sample records for membrane vesicle-mediated release

  1. Porphyromonas gingivalis Outer Membrane Vesicles Mediate Coaggregation and Piggybacking of Treponema denticola and Lachnoanaerobaculum saburreum

    Directory of Open Access Journals (Sweden)

    Daniel Grenier

    2013-01-01

    Full Text Available Porphyromonas gingivalis sheds outer membrane vesicles that contain several virulence factors, including adhesins. In this study, we investigated the ability of P. gingivalis outer membrane vesicles to mediate the coaggregation and piggybacking of Treponema denticola and Lachnoanaerobaculum saburreum. Marked coaggregation between T. denticola and L. saburreum occurred in the presence of P. gingivalis outer membrane vesicles. Sucrose was an effective chemoattractant for the motile species T. denticola. The addition of outer membrane vesicles to a mixture of T. denticola and L. saburreum significantly increased the number of nonmotile bacteria that migrated into a sucrose-filled capillary tube immersed in the bacterial mixture. Under optimal conditions, the number of nonmotile L. saburreum in the capillary tube increased approximately 5-fold, whereas no increase occurred when boiled vesicles were used. This study showed that P. gingivalis outer membrane vesicles mediate coaggregation between T. denticola and L. saburreum and that nonmotile bacteria can be translocated by piggybacking on spirochetes.

  2. Arct'Alg release from hydrogel membranes

    International Nuclear Information System (INIS)

    Amaral, Renata H.; Rogero, Sizue O.; Shihomatsu, Helena M.; Lugao, Ademar B.

    2009-01-01

    The hydrogel properties make them attractive for a variety of biomedical and pharmaceutical applications, primarily in drug delivery system. Synthetic hydrogels have been studied to develop new devices for drugs or cosmetic active agents release. Arct'Alg R is an extract derived from red algae biomass which has antioxidant, anti-inflammatory and tissue regeneration stimulant properties. This extract was incorporated to poly(N-vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) hydrogel membranes obtained by gamma rays crosslinking technique. The ionizing radiation presents the advantage to occur polymerization and sterilization simultaneously in the same process. The aim of this work was the in vitro release kinetic study of Arct'Alg R from hydrogel membranes during 24 hours to verify the possibility of use in cosmetic and dermatological treatments. Results showed that about 50% and 30% of incorporated Arct'Alg R was released from PVP and PVA hydrogel membrane devices respectively. (author)

  3. Preparation of temperature responsive fragrance release membranes by UV curing

    International Nuclear Information System (INIS)

    Nakayama, Hiroshi; Kaetsu, Isao; Uchida, Kumao; Okuda, Jyunya; Kitami, Toshiaki; Matsubara, Yoshio

    2003-01-01

    The authors have studied the preparation and the function of intelligent drug release membranes by UV curing. Temperature responsive fragrance release membranes were prepared by UV curing process and the release functions were investigated as the function of thickness and composition of membrane. Microscopic observations were used to prove the postulated release mechanism

  4. Ceramide transport from endoplasmic reticulum to Golgi apparatus is not vesicle-mediated

    NARCIS (Netherlands)

    Kok, JW; Babia, T; Klappe, K; Egea, G; Hoekstra, D

    1998-01-01

    Ceramide (Cer) transfer from the endoplasmic reticulum (ER) to the Golgi apparatus was measured under conditions that block vesicle-mediated protein transfer. This was done either in intact cells by reducing the incubation temperature to 15 degrees C, or in streptolysin O-permeabilized cells by

  5. Yarrowia lipolytica vesicle-mediated protein transport pathways

    Directory of Open Access Journals (Sweden)

    Beckerich Jean-Marie

    2007-11-01

    Full Text Available Abstract Background Protein secretion is a universal cellular process involving vesicles which bud and fuse between organelles to bring proteins to their final destination. Vesicle budding is mediated by protein coats; vesicle targeting and fusion depend on Rab GTPase, tethering factors and SNARE complexes. The Génolevures II sequencing project made available entire genome sequences of four hemiascomycetous yeasts, Yarrowia lipolytica, Debaryomyces hansenii, Kluyveromyces lactis and Candida glabrata. Y. lipolytica is a dimorphic yeast and has good capacities to secrete proteins. The translocation of nascent protein through the endoplasmic reticulum membrane was well studied in Y. lipolytica and is largely co-translational as in the mammalian protein secretion pathway. Results We identified S. cerevisiae proteins involved in vesicular secretion and these protein sequences were used for the BLAST searches against Génolevures protein database (Y. lipolytica, C. glabrata, K. lactis and D. hansenii. These proteins are well conserved between these yeasts and Saccharomyces cerevisiae. We note several specificities of Y. lipolytica which may be related to its good protein secretion capacities and to its dimorphic aspect. An expansion of the Y. lipolytica Rab protein family was observed with autoBLAST and the Rab2- and Rab4-related members were identified with BLAST against NCBI protein database. An expansion of this family is also found in filamentous fungi and may reflect the greater complexity of the Y. lipolytica secretion pathway. The Rab4p-related protein may play a role in membrane recycling as rab4 deleted strain shows a modification of colony morphology, dimorphic transition and permeability. Similarly, we find three copies of the gene (SSO encoding the plasma membrane SNARE protein. Quantification of the percentages of proteins with the greatest homology between S. cerevisiae, Y. lipolytica and animal homologues involved in vesicular

  6. Controlled release of curcumin from poly(HEMA-MAPA) membrane.

    Science.gov (United States)

    Caka, Müşerref; Türkcan, Ceren; Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

    2017-05-01

    In this work, poly(HEMA-MAPA) membranes were prepared by UV-polymerization technique. These membranes were characterized by SEM, FTIR, and swelling studies. Synthesized membranes had high porous structure. These membranes were used for controlled release of curcumin which is already used as folk remedy and used as drug for some certain diseases and cancers. Curcumin release was investigated for various pHs and temperatures. Optimum drug release yield was found to be as 70% at pH 7.4 and 37 °C within 2 h period. Time-depended release of curcumin was also investigated and its slow release from the membrane demonstrated within 48 h.

  7. diffusion of metronidazole released through cellulose membrane

    African Journals Online (AJOL)

    prof kokwaro

    was determined using dialyzing cellulose membrane in a dissolution tester. Glycerin, a permeation ... An attempt has been made in the present ... Materials. Metronidazole USP was donated by Cosmos. Pharmaceutical Ltd., Nairobi, Kenya.

  8. Validation of kinetic modeling of progesterone release from polymeric membranes

    Directory of Open Access Journals (Sweden)

    Analia Irma Romero

    2018-01-01

    Full Text Available Mathematical modeling in drug release systems is fundamental in development and optimization of these systems, since it allows to predict drug release rates and to elucidate the physical transport mechanisms involved. In this paper we validate a novel mathematical model that describes progesterone (Prg controlled release from poly-3-hydroxybutyric acid (PHB membranes. A statistical analysis was conducted to compare the fitting of our model with six different models and the Akaike information criterion (AIC was used to find the equation with best-fit. A simple relation between mass and drug released rate was found, which allows predicting the effect of Prg loads on the release behavior. Our proposed model was the one with minimum AIC value, and therefore it was the one that statistically fitted better the experimental data obtained for all the Prg loads tested. Furthermore, the initial release rate was calculated and therefore, the interface mass transfer coefficient estimated and the equilibrium distribution constant of Prg between the PHB and the release medium was also determined. The results lead us to conclude that our proposed model is the one which best fits the experimental data and can be successfully used to describe Prg drug release in PHB membranes.

  9. Ultrastructural analysis of nanoparticles and ions released in periprosthetic membranes.

    Science.gov (United States)

    Sabbatini, Maurizio; Gatti, Giorgio; Renò, Filippo; Bosetti, Michela; Marchese, Leonardo; Cannas, Mario

    2014-12-30

    The distribution and relationship of hydroxyapatite debris, nanometric organic and metal wear particles and metal ions on periimplant interface membranes following aseptic and septic arthroplastic loosening were investigated. Scanning electron microscopy and X-ray spectroscopic analysis were used to analyze debris and ion distribution. Hydroxyapatite debris appeared with different morphology in a particular distribution among several membranes. These differences may reflect the occurrence of different friction forces taking place between prosthesis and bone interface in the several types of prostheses studied. Metal wear particles were detected in greater numbers in membranes from noncemented prostheses compared with those from cemented ones. In contrast, more organic particles were present in membrane from cemented prosthesis. No differences were observed between aseptic and septic membranes. Our findings support the need to evaluate the occurrence of friction forces that periprosthetic bone debris production may induce to exacerbate cellular reactivity. Furthermore, cellular engulfment of debris and the high level of different ions released indicate the occurrence of a toxic environment that may induce failure of any reparative pathways.

  10. Ciprofloxacin release using natural rubber latex membranes as carrier.

    Science.gov (United States)

    Dias Murbach, Heitor; Jaques Ogawa, Guilherme; Azevedo Borges, Felipe; Romeiro Miranda, Matheus Carlos; Lopes, Rute; Roberto de Barros, Natan; Guedes Mazalli, Alexandre Vinicius; Gonçalves da Silva, Rosângela; Ferreira Cinman, José Luiz; de Camargo Drago, Bruno; Donizetti Herculano, Rondinelli

    2014-01-01

    Natural rubber latex (NRL) from Hevea brasiliensis is easily manipulated, low cost, is of can stimulate natural angiogenesis and cellular adhesion, is a biocompatible, material and presents high mechanical resistance. Ciprofloxacin (CIP) is a synthetic antibiotic (fluoroquinolone) used in the treatment of infection at external fixation screws sites and remote infections, and this use is increasingly frequent in medical practice. The aim of this study was to develop a novel sustained delivery system for CIP based on NRL membranes and to study its delivery system behavior. CIP was found to be adsorbed on the NRL membrane, according to results of energy dispersive X-ray spectroscopy. Results show that the membrane can release CIP for up to 59.08% in 312 hours and the mechanism is due to super case II (non-Fickian). The kinetics of the drug release could be fitted with double exponential function X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy shows some interaction by hydrogen bound, which influences its mechanical behavior.

  11. PH-triggered micellar membrane for controlled release microchips

    KAUST Repository

    Yang, Xiaoqiang

    2011-01-01

    A pH-responsive membrane based on polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer was developed on a model glass microchip as a promising controlled polymer delivery system. The PS-b-P4VP copolymer assembles into spherical and/or worm-like micelles with styrene block cores and pyridine coronas in selective solvents. The self-assembled worm-like morphology exhibited pH-responsive behaviour due to the protonation of the P4VP block at low pH and it\\'s deprotonation at high pH and thus constituting a switchable "off/on" system. Doxorubicin (Dox) was used as cargo to test the PS-b-P4VP membrane. Luminescence experiments indicated that the membrane was able to store Dox molecules within its micellar structure at neutral pH and then release them as soon as the pH was raised to 8.0. The performance of the cast membrane was predictable and most importantly reproducible. The physiochemical and biological properties were also investigated carefully in terms of morphology, cell viability and cell uptake. This journal is © The Royal Society of Chemistry.

  12. Coxsackievirus protein 2B modifies endoplasmic reticulum membrane and plasma membrane permeability and facilitates virus release.

    Science.gov (United States)

    van Kuppeveld, F J; Hoenderop, J G; Smeets, R L; Willems, P H; Dijkman, H B; Galama, J M; Melchers, W J

    1997-01-01

    Digital-imaging microscopy was performed to study the effect of Coxsackie B3 virus infection on the cytosolic free Ca2+ concentration and the Ca2+ content of the endoplasmic reticulum (ER). During the course of infection a gradual increase in the cytosolic free Ca2+ concentration was observed, due to the influx of extracellular Ca2+. The Ca2+ content of the ER decreased in time with kinetics inversely proportional to those of viral protein synthesis. Individual expression of protein 2B was sufficient to induce the influx of extracellular Ca2+ and to release Ca2+ from ER stores. Analysis of mutant 2B proteins showed that both a cationic amphipathic alpha-helix and a second hydrophobic domain in 2B were required for these activities. Consistent with a presumed ability of protein 2B to increase membrane permeability, viruses carrying a mutant 2B protein exhibited a defect in virus release. We propose that 2B gradually enhances membrane permeability, thereby disrupting the intracellular Ca2+ homeostasis and ultimately causing the membrane lesions that allow release of virus progeny. PMID:9218794

  13. Atomic force microscopy analysis of synthetic membranes applied in release studies

    Energy Technology Data Exchange (ETDEWEB)

    Olejnik, Anna, E-mail: annamar@amu.edu.pl; Nowak, Izabela

    2015-11-15

    Graphical abstract: - Highlights: • We compare eight synthetic membranes by atomic force microscopy. • We predict the behavior of membranes in the release experiments. • The polymeric synthetic membranes varied in shape and size. • We detect substructures in pores of cellulose esters and nylon membranes. • Substructures limit the release rate of active compound. - Abstract: Synthetic membranes are commonly used in drug release studies and are applied mostly in quality control. They contain pores through which the drug can be diffused directly into the receptor fluid. Investigation of synthetic membranes permits determination of their structure and characterization of their properties. We suggest that the preliminary characterization of the membranes can be relevant to the interpretation of the release results. The aim of this study was to compare eight synthetic membranes by using atomic force microscopy in order to predict and understand their behavior in the release experiments. The results proved that polytetrafluoroethylene membrane was not suitable for the release study of tetrapeptide due to its hydrophobic nature, thickness and the specific structure with high trapezoid shaped blocks. The additional substructures in pores of mixed cellulose esters and nylon membranes detected by AFM influenced the diffusion rate of the active compound. These findings indicate that the selection of the membrane for the release studies should be performed cautiously by taking into consideration the membrane properties and by analyzing them prior the experiment.

  14. Atomic force microscopy analysis of synthetic membranes applied in release studies

    International Nuclear Information System (INIS)

    Olejnik, Anna; Nowak, Izabela

    2015-01-01

    Graphical abstract: - Highlights: • We compare eight synthetic membranes by atomic force microscopy. • We predict the behavior of membranes in the release experiments. • The polymeric synthetic membranes varied in shape and size. • We detect substructures in pores of cellulose esters and nylon membranes. • Substructures limit the release rate of active compound. - Abstract: Synthetic membranes are commonly used in drug release studies and are applied mostly in quality control. They contain pores through which the drug can be diffused directly into the receptor fluid. Investigation of synthetic membranes permits determination of their structure and characterization of their properties. We suggest that the preliminary characterization of the membranes can be relevant to the interpretation of the release results. The aim of this study was to compare eight synthetic membranes by using atomic force microscopy in order to predict and understand their behavior in the release experiments. The results proved that polytetrafluoroethylene membrane was not suitable for the release study of tetrapeptide due to its hydrophobic nature, thickness and the specific structure with high trapezoid shaped blocks. The additional substructures in pores of mixed cellulose esters and nylon membranes detected by AFM influenced the diffusion rate of the active compound. These findings indicate that the selection of the membrane for the release studies should be performed cautiously by taking into consideration the membrane properties and by analyzing them prior the experiment.

  15. The effects of membrane cholesterol and simvastatin on red blood cell deformability and ATP release.

    Science.gov (United States)

    Forsyth, Alison M; Braunmüller, Susanne; Wan, Jiandi; Franke, Thomas; Stone, Howard A

    2012-05-01

    It is known that deformation of red blood cells (RBCs) is linked to ATP release from the cells. Further, membrane cholesterol has been shown to alter properties of the cell membrane such as fluidity and bending stiffness. Membrane cholesterol content is increased in some cardiovascular diseases, for example, in individuals with acute coronary syndromes and chronic stable angina, and therefore, because of the potential clinical relevance, we investigated the influence of altered RBC membrane cholesterol levels on ATP release. Because of the correlation between statins and reduced membrane cholesterol in vivo, we also investigated the effects of simvastatin on RBC deformation and ATP release. We found that reducing membrane cholesterol increases cell deformability and ATP release. We also found that simvastatin increases deformability by acting directly on the membrane in the absence of the liver, and that ATP release was increased for cells with enriched cholesterol after treatment with simvastatin. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. The membrane fraction of homogenized rat kidney contains an enzyme that releases epidermal growth factor from the kidney membranes

    DEFF Research Database (Denmark)

    Nexø, Ebba; Poulsen, Steen Seier

    1991-01-01

    shows that the membrane fraction of homogenized rat kidney contains an enzyme that releases immuno and receptor reactive EGF from the kidney membranes when incubated at 37 degrees C. Gel filtration shows that the EGF reactivity released from the membranes is similar to the EGF reactivity in rat urine......High levels of epidermal growth factor (EGF) are excreted in the urine and high levels of mRNA for the EGF-precursor have been demonstrated in the kidney. The EGF-precursor is a membrane bound peptide in the kidney, but little is known about the renal processing of the precursor. The present study...

  17. Extracellular vesicles mediate signaling between the aqueous humor producing and draining cells in the ocular system.

    Science.gov (United States)

    Lerner, Natalie; Avissar, Sofia; Beit-Yannai, Elie

    2017-01-01

    Canonical Wnt signaling is associated with glaucoma pathogenesis and intraocular pressure (IOP) regulation. Our goal was to gain insight into the influence of non-pigmented ciliary epithelium (NPCE)-derived exosomes on Wnt signaling by trabecular meshwork (TM) cells. The potential impact of exosomes on Wnt signaling in the ocular drainage system remains poorly understood. Exosomes isolated from media collected from cultured NPCE cells by differential ultracentrifugation were characterized by dynamic light scattering (DLS), tunable resistive pulse sensing (TRPS), and nanoparticle tracking analysis (NTA), sucrose density gradient migration and transmission electron microscopy (TEM). The cellular target specificity of the NPCE-derived exosomes was investigated by confocal microscopy-based monitoring of the uptake of DiD-labeled exosomes over time, as compared to uptake by various cell lines. Changes in Wnt protein levels in TM cells induced by NPCE exosomes were evaluated by Western blot. Exosomes derived from NPCE cells were purified and detected as small rounded 50-140 nm membrane vesicles, as defined by DLS, NTA, TRPS and TEM. Western blot analysis indicated that the nanovesicles were positive for classic exosome markers, including Tsg101 and Alix. Isolated nanoparticles were found in sucrose density fractions typical of exosomes (1.118-1.188 g/mL sucrose). Using confocal microscopy, we demonstrated time-dependent specific accumulation of the NPCE-derived exosomes in NTM cells. Other cell lines investigated hardly revealed any exosome uptake. We further showed that exosomes induced changes in Wnt signaling protein expression in the TM cells. Western blot analysis further revealed decreased phosphorylation of GKS3β and reduced β-catenin levels. Finally, we found that treatment of NTM cells with exosomes resulted in a greater than 2-fold decrease in the level of β-catenin in the cytosolic fraction. In contrast, no remarkable difference in the amount of

  18. Photocuring of stimulus responsive membranes for controlled-release of drugs having different molecular weights

    International Nuclear Information System (INIS)

    Ng, Loo-Teck; Nakayama, Hiroshi; Kaetsu, Isao; Uchida, Kumao

    2005-01-01

    Intelligent drug delivery membranes were prepared by photocuring poly(acrylic acid) coatings onto poly(2-hydroxyethyl methacrylate) membranes each with model drugs of different molecular weights being incorporated. pH-responsive release behaviours of the model drugs which included sodium salicylate, nicotinamide, nicotinic acid, methylene blue, brilliant green and crystal violet were investigated. Only the membrane with methylene blue incorporated showed a clear pH-responsive release and other drug-incorporated membranes showed no intelligent behaviour. These phenomena were explained in terms of the difference in diffusivity of drugs through polymer matrices of the membranes attributable to the difference in the molecular weights of drugs

  19. Photocuring of stimulus responsive membranes for controlled-release of drugs having different molecular weights

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Loo-Teck [School of Science, Food and Horticulture, University of Western Sydney, Locked bag 1797, Penrith South DC, NSW 1797 (Australia)]. E-mail: l.ng@uws.edu.au; Nakayama, Hiroshi [Department of Nuclear Engineering, Faculty of Science and technology, Kinki University, Kowakae, 3-4-1, Higashi-Osaka 577-8502 (Japan); Kaetsu, Isao [Department of Nuclear Engineering, Faculty of Science and technology, Kinki University, Kowakae, 3-4-1, Higashi-Osaka 577-8502 (Japan)]. E-mail: kaetsu@ned.kindai.ac.jp; Uchida, Kumao [Department of Nuclear Engineering, Faculty of Science and technology, Kinki University, Kowakae, 3-4-1, Higashi-Osaka 577-8502 (Japan)

    2005-06-01

    Intelligent drug delivery membranes were prepared by photocuring poly(acrylic acid) coatings onto poly(2-hydroxyethyl methacrylate) membranes each with model drugs of different molecular weights being incorporated. pH-responsive release behaviours of the model drugs which included sodium salicylate, nicotinamide, nicotinic acid, methylene blue, brilliant green and crystal violet were investigated. Only the membrane with methylene blue incorporated showed a clear pH-responsive release and other drug-incorporated membranes showed no intelligent behaviour. These phenomena were explained in terms of the difference in diffusivity of drugs through polymer matrices of the membranes attributable to the difference in the molecular weights of drugs.

  20. Fusion of Selected Cells and Vesicles Mediated by Optically Trapped Plasmonic Nanoparticles

    DEFF Research Database (Denmark)

    Bahadori, Azra

    . In this work, we introduce a novel and extremely flexible physical method which can trigger membrane fusion in a highly selective manner not only between synthetic GUVs of different compositions, but also between live cells which remain viable after fusion. Optical tweezers’ laser (1064 nm) is used to position....... The concept of cellular delivery is also known as targeted drug delivery and is quite a hot research topic internationally. Therefore, there have been efforts to develop various chemical molecules, proteins/peptides and physical approaches to trigger membrane fusion between synthetic giant unilamellar...... and merging of the two membranes results in merging the two membranes thereby completes the fusion. Complete fusion is associated with lipid mixing and lumen mixing which are both imaged by a high resolution confocal microscope. The confocal imaging enables quantification of the associated lipid mixing...

  1. Lipid vesicle-mediated affinity chromatography using magnetic activated cell sorting (LIMACS): a novel method to analyze protein-lipid interaction.

    Science.gov (United States)

    Bieberich, Erhard

    2011-04-26

    The analysis of lipid protein interaction is difficult because lipids are embedded in cell membranes and therefore, inaccessible to most purification procedures. As an alternative, lipids can be coated on flat surfaces as used for lipid ELISA and Plasmon resonance spectroscopy. However, surface coating lipids do not form microdomain structures, which may be important for the lipid binding properties. Further, these methods do not allow for the purification of larger amounts of proteins binding to their target lipids. To overcome these limitations of testing lipid protein interaction and to purify lipid binding proteins we developed a novel method termed lipid vesicle-mediated affinity chromatography using magnetic-activated cell sorting (LIMACS). In this method, lipid vesicles are prepared with the target lipid and phosphatidylserine as the anchor lipid for Annexin V MACS. Phosphatidylserine is a ubiquitous cell membrane phospholipid that shows high affinity to the protein Annexin V. Using magnetic beads conjugated to Annexin V the phosphatidylserine-containing lipid vesicles will bind to the magnetic beads. When the lipid vesicles are incubated with a cell lysate the protein binding to the target lipid will also be bound to the beads and can be co-purified using MACS. This method can also be used to test if recombinant proteins reconstitute a protein complex binding to the target lipid. We have used this method to show the interaction of atypical PKC (aPKC) with the sphingolipid ceramide and to co-purify prostate apoptosis response 4 (PAR-4), a protein binding to ceramide-associated aPKC. We have also used this method for the reconstitution of a ceramide-associated complex of recombinant aPKC with the cell polarity-related proteins Par6 and Cdc42. Since lipid vesicles can be prepared with a variety of sphingo- or phospholipids, LIMACS offers a versatile test for lipid-protein interaction in a lipid environment that resembles closely that of the cell membrane

  2. Structure and function of ABCG2-rich extracellular vesicles mediating multidrug resistance.

    Directory of Open Access Journals (Sweden)

    Vicky Goler-Baron

    2011-01-01

    Full Text Available Multidrug resistance (MDR is a major impediment to curative cancer chemotherapy. The ATP-Binding Cassette transporters ABCG2, ABCB1 and ABCC2 form a unique defense network against multiple structurally and functionally distinct chemotherapeutics, thereby resulting in MDR. Thus, deciphering novel mechanisms of MDR and their overcoming is a major goal of cancer research. Recently we have shown that overexpression of ABCG2 in the membrane of novel extracellular vesicles (EVs in breast cancer cells results in mitoxantrone resistance due to its dramatic sequestration in EVs. However, nothing is known about EVs structure, biogenesis and their ability to concentrate multiple antitumor agents. To this end, we here found that EVs are structural and functional homologues of bile canaliculi, are apically localized, sealed structures reinforced by an actin-based cytoskeleton and secluded from the extracellular milieu by the tight junction proteins occludin and ZO-1. Apart from ABCG2, ABCB1 and ABCC2 were also selectively targeted to the membrane of EVs. Moreover, Ezrin-Radixin-Moesin protein complex selectively localized to the border of the EVs membrane, suggesting a key role for the tethering of MDR pumps to the actin cytoskeleton. The ability of EVs to concentrate and sequester different antitumor drugs was also explored. Taking advantage of the endogenous fluorescence of anticancer drugs, we found that EVs-forming breast cancer cells display high level resistance to topotecan, imidazoacridinones and methotrexate via efficient intravesicular drug concentration hence sequestering them away from their cellular targets. Thus, we identified a new modality of anticancer drug compartmentalization and resistance in which multiple chemotherapeutics are actively pumped from the cytoplasm and highly concentrated within the lumen of EVs via a network of MDR transporters differentially targeted to the EVs membrane. We propose a composite model for the structure and

  3. Sustained transdermal release of diltiazem hydrochloride through electron beam irradiated different PVA hydrogel membranes

    Energy Technology Data Exchange (ETDEWEB)

    Bhunia, Tridib [Department of Polymer Science and Technology, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India); Goswami, Luna [KIIT School of Biotechnology, KIIT University Campus XI, Patia, Bhubaneswar 751024, Orissa (India); Chattopadhyay, Dipankar [Department of Polymer Science and Technology, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India); Bandyopadhyay, Abhijit, E-mail: abpoly@caluniv.ac.in [Department of Polymer Science and Technology, University of Calcutta, 92 A.P.C. Road, Calcutta 700009 (India)

    2011-08-15

    Extremely fast release of diltiazem hydrochloride (water soluble, anti anginal drug used to treat chest pain) together with its faster erosion has been the primary problem in conventional oral therapy. It has been addressed in this paper by encapsulating the drug in electron beam irradiated various poly (vinyl alcohol) hydrogel membranes and delivering it through transdermal route. Results show excellent control over the release of diltiazem hydrochloride through these membranes subject to their physico-mechanicals.

  4. Sustained transdermal release of diltiazem hydrochloride through electron beam irradiated different PVA hydrogel membranes

    Science.gov (United States)

    Bhunia, Tridib; Goswami, Luna; Chattopadhyay, Dipankar; Bandyopadhyay, Abhijit

    2011-08-01

    Extremely fast release of diltiazem hydrochloride (water soluble, anti anginal drug used to treat chest pain) together with its faster erosion has been the primary problem in conventional oral therapy. It has been addressed in this paper by encapsulating the drug in electron beam irradiated various poly (vinyl alcohol) hydrogel membranes and delivering it through transdermal route. Results show excellent control over the release of diltiazem hydrochloride through these membranes subject to their physico-mechanicals.

  5. Sustained transdermal release of diltiazem hydrochloride through electron beam irradiated different PVA hydrogel membranes

    International Nuclear Information System (INIS)

    Bhunia, Tridib; Goswami, Luna; Chattopadhyay, Dipankar; Bandyopadhyay, Abhijit

    2011-01-01

    Extremely fast release of diltiazem hydrochloride (water soluble, anti anginal drug used to treat chest pain) together with its faster erosion has been the primary problem in conventional oral therapy. It has been addressed in this paper by encapsulating the drug in electron beam irradiated various poly (vinyl alcohol) hydrogel membranes and delivering it through transdermal route. Results show excellent control over the release of diltiazem hydrochloride through these membranes subject to their physico-mechanicals.

  6. Lateral release of proteins from the TOM complex into the outer membrane of mitochondria.

    Science.gov (United States)

    Harner, Max; Neupert, Walter; Deponte, Marcel

    2011-07-15

    The TOM complex of the outer membrane of mitochondria is the entry gate for the vast majority of precursor proteins that are imported into the mitochondria. It is made up by receptors and a protein conducting channel. Although precursor proteins of all subcompartments of mitochondria use the TOM complex, it is not known whether its channel can only mediate passage across the outer membrane or also lateral release into the outer membrane. To study this, we have generated fusion proteins of GFP and Tim23 which are inserted into the inner membrane and, at the same time, are spanning either the TOM complex or are integrated into the outer membrane. Our results demonstrate that the TOM complex, depending on sequence determinants in the precursors, can act both as a protein conducting pore and as an insertase mediating lateral release into the outer membrane.

  7. InAs migration on released, wrinkled InGaAs membranes used as virtual substrate

    International Nuclear Information System (INIS)

    Filipe Covre da Silva, S; Lanzoni, E M; De Araujo Barboza, V; Deneke, Ch; Malachias, A; Kiravittaya, S

    2014-01-01

    Partly released, relaxed and wrinkled InGaAs membranes are used as virtual substrates for overgrowth with InAs. Such samples exhibit different lattice parameters for the unreleased epitaxial parts, the released flat, back-bond areas and the released wrinkled areas. A large InAs migration towards the released membrane is observed with a material accumulation on top of the freestanding wrinkles during overgrowth. A semi-quantitative analysis of the misfit strain shows that the material migrates to the areas of the sample with the lowest misfit strain, which we consider as the areas of the lowest chemical potential of the surface. Material migration is also observed for the edge-supported, freestanding InGaAs membranes found on these samples. Our results show that the released, wrinkled nanomembranes offer a growth template for InAs deposition that fundamentally changes the migration behavior of the deposited material on the growth surface. (paper)

  8. SV40 late protein VP4 forms toroidal pores to disrupt membranes for viral release.

    Science.gov (United States)

    Raghava, Smita; Giorda, Kristina M; Romano, Fabian B; Heuck, Alejandro P; Hebert, Daniel N

    2013-06-04

    Nonenveloped viruses are generally released from the cell by the timely lysis of host cell membranes. SV40 has been used as a model virus for the study of the lytic nonenveloped virus life cycle. The expression of SV40 VP4 at later times during infection is concomitant with cell lysis. To investigate the role of VP4 in viral release and its mechanism of action, VP4 was expressed and purified from bacteria as a fusion protein for use in membrane disruption assays. Purified VP4 perforated membranes as demonstrated by the release of fluorescent markers encapsulated within large unilamellar vesicles or liposomes. Dynamic light scattering results revealed that VP4 treatment did not cause membrane lysis or change the size of the liposomes. Liposomes encapsulated with 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-3-indacene-labeled streptavidin were used to show that VP4 formed stable pores in membranes. These VP4 pores had an inner diameter of 1-5 nm. Asymmetrical liposomes containing pyrene-labeled lipids in the outer monolayer were employed to monitor transbilayer lipid diffusion. Consistent with VP4 forming toroidal pore structures in membranes, VP4 induced transbilayer lipid diffusion or lipid flip-flop. Altogether, these studies support a central role for VP4 acting as a viroporin in the disruption of cellular membranes to trigger SV40 viral release by forming toroidal pores that unite the outer and inner leaflets of membrane bilayers.

  9. PH-triggered micellar membrane for controlled release microchips

    KAUST Repository

    Yang, Xiaoqiang; Moosa, Basem; Deng, Lin; Zhao, Lan; Khashab, Niveen M.

    2011-01-01

    A pH-responsive membrane based on polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer was developed on a model glass microchip as a promising controlled polymer delivery system. The PS-b-P4VP copolymer assembles into spherical and

  10. Controlled release of mitomycin C from PHEMAH-Cu(II) cryogel membranes.

    Science.gov (United States)

    Bakhshpour, Monireh; Yavuz, Handan; Denizli, Adil

    2018-02-19

    Molecular imprinting technique was used for the preparation of antibiotic and anti-neoplastic chemotherapy drug (mitomycin C) imprinted cryogel membranes (MMC-ICM). The membranes were synthezied by using metal ion coordination interactions with N-methacryloyl-(l)-histidine methyl ester (MAH) functional monomer and template molecules (i.e. MMC). The 2-hydroxyethyl methacrylate (HEMA) monomer and methylene bisacrylamide (MBAAm) crosslinker were used for the preparation of mitomycin C imprinted cryogel membranes by radical suspension polymerization technique. The imprinted cryogel membranes were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and swelling degree measurements. Cytotoxicity of MMC-ICMs was investigated using mouse fibroblast cell line L929. Time-dependent release of MMC was demonstrated within 150 h from cryogel membranes. Cryogels demonstrated very high MMC loading efficiency (70-80%) and sustained MMC release over hours.

  11. Membrane properties involved in calcium-stimulated microparticle release from the plasma membranes of S49 lymphoma cells.

    Science.gov (United States)

    Campbell, Lauryl E; Nelson, Jennifer; Gibbons, Elizabeth; Judd, Allan M; Bell, John D

    2014-01-01

    This study answered the question of whether biophysical mechanisms for microparticle shedding discovered in platelets and erythrocytes also apply to nucleated cells: cytoskeletal disruption, potassium efflux, transbilayer phospholipid migration, and membrane disordering. The calcium ionophore, ionomycin, disrupted the actin cytoskeleton of S49 lymphoma cells and produced rapid release of microparticles. This release was significantly inhibited by interventions that impaired calcium-activated potassium current. Microparticle release was also greatly reduced in a lymphocyte cell line deficient in the expression of scramblase, the enzyme responsible for calcium-stimulated dismantling of the normal phospholipid transbilayer asymmetry. Rescue of the scrambling function at high ionophore concentration also resulted in enhanced particle shedding. The effect of membrane physical properties was addressed by varying the experimental temperature (32-42°C). A significant positive trend in the rate of microparticle release as a function of temperature was observed. Fluorescence experiments with trimethylammonium diphenylhexatriene and Patman revealed significant decrease in the level of apparent membrane order along that temperature range. These results demonstrated that biophysical mechanisms involved in microparticle release from platelets and erythrocytes apply also to lymphocytes.

  12. Modulation of the effect of acetylcholine on insulin release by the membrane potential of B cells

    International Nuclear Information System (INIS)

    Hermans, M.P.; Schmeer, W.; Henquin, J.C.

    1987-01-01

    Mouse islets were used to test the hypothesis that the B cell membrane must be depolarized for acetylcholine to increase insulin release. The resting membrane potential of B cells (at 3 mM glucose) was slightly decreased (5 mV) by acetylcholine, but no electrical activity appeared. This depolarization was accompanied by a Ca-independent acceleration of 86 Rb and 45 Ca efflux but no insulin release. When the B cell membrane was depolarized by a stimulatory concentration of glucose (10 mM), acetylcholine potentiated electrical activity, accelerated 86 Rb and 45 Ca efflux, and increased insulin release. This latter effect, but not the acceleration of 45 Ca efflux, was totally dependent on extracellular Ca. If glucose-induced depolarization of the B cell membrane was prevented by diazoxide, acetylcholine lost all effects but those produced at low glucose. In contrast, when the B cell membrane was depolarized by leucine or tolbutamide (at 3 mM glucose), acetylcholine triggered a further depolarization with appearance of electrical activity, accelerated 86 Rb and 45 Ca efflux, and stimulated insulin release. Acetylcholine produced similar effects (except for electrical activity) in the presence of high K or arginine which, unlike the above test agents, depolarize the B cell membrane by a mechanism other than a decrease in K+ permeability. Omission of extracellular Ca abolished the releasing effect of acetylcholine under all conditions but only partially decreased the stimulation of 45 Ca efflux. The results show thus that acetylcholine stimulation of insulin release does not result from mobilization of cellular Ca but requires that the B cell membrane be sufficiently depolarized to reach the threshold potential where Ca channels are activated. This may explain why acetylcholine alone does not initiate release but becomes active in the presence of a variety of agents

  13. Membrane-bound transcription factors: regulated release by RIP or RUP.

    Science.gov (United States)

    Hoppe, T; Rape, M; Jentsch, S

    2001-06-01

    Regulated nuclear transport of transcription factors from cytoplasmic pools is a major route by which eukaryotes control gene expression. Exquisite examples are transcription factors that are kept in a dormant state in the cytosol by membrane anchors; such proteins are released from membranes by proteolytic cleavage, which enables these transcription factors to enter the nucleus. Cleavage can be mediated either by regulated intramembrane proteolysis (RIP) catalysed by specific membrane-bound proteases or by regulated ubiquitin/proteasome-dependent processing (RUP). In both cases processing can be controlled by cues that originate at or in the vicinity of the membrane.

  14. Exosomes account for vesicle-mediated transcellular transport of activatable phospholipases and prostaglandins[S

    Science.gov (United States)

    Subra, Caroline; Grand, David; Laulagnier, Karine; Stella, Alexandre; Lambeau, Gérard; Paillasse, Michael; De Medina, Philippe; Monsarrat, Bernard; Perret, Bertrand; Silvente-Poirot, Sandrine; Poirot, Marc; Record, Michel

    2010-01-01

    Exosomes are bioactive vesicles released from multivesicular bodies (MVB) by intact cells and participate in intercellular signaling. We investigated the presence of lipid-related proteins and bioactive lipids in RBL-2H3 exosomes. Besides a phospholipid scramblase and a fatty acid binding protein, the exosomes contained the whole set of phospholipases (A2, C, and D) together with interacting proteins such as aldolase A and Hsp 70. They also contained the phospholipase D (PLD) / phosphatidate phosphatase 1 (PAP1) pathway leading to the formation of diglycerides. RBL-2H3 exosomes also carried members of the three phospholipase A2 classes: the calcium-dependent cPLA2-IVA, the calcium-independent iPLA2-VIA, and the secreted sPLA2-IIA and V. Remarkably, almost all members of the Ras GTPase superfamily were present, and incubation of exosomes with GTPγS triggered activation of phospholipase A2 (PLA2)and PLD2. A large panel of free fatty acids, including arachidonic acid (AA) and derivatives such as prostaglandin E2 (PGE2) and 15-deoxy-Δ12,14-prostaglandinJ2 (15-d PGJ2), were detected. We observed that the exosomes were internalized by resting and activated RBL cells and that they accumulated in an endosomal compartment. Endosomal concentrations were in the micromolar range for prostaglandins; i.e., concentrations able to trigger prostaglandin-dependent biological responses. Therefore exosomes are carriers of GTP-activatable phospholipases and lipid mediators from cell to cell. PMID:20424270

  15. Pannexin 1 channels mediate 'find-me' signal release and membrane permeability during apoptosis.

    Science.gov (United States)

    Chekeni, Faraaz B; Elliott, Michael R; Sandilos, Joanna K; Walk, Scott F; Kinchen, Jason M; Lazarowski, Eduardo R; Armstrong, Allison J; Penuela, Silvia; Laird, Dale W; Salvesen, Guy S; Isakson, Brant E; Bayliss, Douglas A; Ravichandran, Kodi S

    2010-10-14

    Apoptotic cells release 'find-me' signals at the earliest stages of death to recruit phagocytes. The nucleotides ATP and UTP represent one class of find-me signals, but their mechanism of release is not known. Here, we identify the plasma membrane channel pannexin 1 (PANX1) as a mediator of find-me signal/nucleotide release from apoptotic cells. Pharmacological inhibition and siRNA-mediated knockdown of PANX1 led to decreased nucleotide release and monocyte recruitment by apoptotic cells. Conversely, PANX1 overexpression enhanced nucleotide release from apoptotic cells and phagocyte recruitment. Patch-clamp recordings showed that PANX1 was basally inactive, and that induction of PANX1 currents occurred only during apoptosis. Mechanistically, PANX1 itself was a target of effector caspases (caspases 3 and 7), and a specific caspase-cleavage site within PANX1 was essential for PANX1 function during apoptosis. Expression of truncated PANX1 (at the putative caspase cleavage site) resulted in a constitutively open channel. PANX1 was also important for the 'selective' plasma membrane permeability of early apoptotic cells to specific dyes. Collectively, these data identify PANX1 as a plasma membrane channel mediating the regulated release of find-me signals and selective plasma membrane permeability during apoptosis, and a new mechanism of PANX1 activation by caspases.

  16. Pharmacological aspects of release from microcapsules - from polymeric multilayers to lipid membranes.

    Science.gov (United States)

    Wuytens, Pieter; Parakhonskiy, Bogdan; Yashchenok, Alexey; Winterhalter, Mathias; Skirtach, Andre

    2014-10-01

    This review is devoted to pharmacological applications of principles of release from capsules to overcome the membrane barrier. Many of these principles were developed in the context of polymeric multilayer capsule membrane modulation, but they are also pertinent to liposomes, polymersomes, capsosomes, particles, emulsion-based carriers and other carriers. We look at these methods from the physical, chemical or biological driving mechanisms point of view. In addition to applicability for carriers in drug delivery, these release methods are significant for another area directly related to pharmacology - modulation of the permeability of the membranes and thus promoting the action of drugs. Emerging technologies, including ionic current monitoring through a lipid membrane on a nanopore, are also highlighted. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Electrospun Gelatin/poly(Glycerol Sebacate Membrane with Controlled Release of Antibiotics for Wound Dressing

    Directory of Open Access Journals (Sweden)

    Parisa Shirazaki

    2017-01-01

    Full Text Available Background: The most important risk that threatens the skin wounds is infections. Therefore, fabrication of a membrane as a wound dressing with the ability of antibiotic delivery in a proper delivery rate is especially important. Materials and Methods: Poly(glycerol sebacate (PGS was prepared from sebacic acid and glycerol with 1:1 ratio; then, it was added to gelatin in the 1:3 ratio and was dissolved in 80% (v/v acetic acid, and finally, ciprofloxacin was added in 10% (w/v of polymer solution. The gelatin/PGS membrane was fabricated using an electrospinning method. The membrane was cross-linked using ethyl-3-(3-dimethylaminopropyl carbodiimide ethyl-3-(3-dimethylaminopropylcarbodiim (EDC and N-hydroxysuccinimide (NHS in different time periods to achieve a proper drug release rate. Fourier-transform infrared (FTIR spectroscopy was being used to manifest the peaks of polymers and drug in the membrane. Scanning electron microscopy (SEM was used to evaluate the morphology, fibers diameter, pore size, and porosity before and after crosslinking process. Ultraviolet (UV-visible spectrophotometry was used to show the ciprofloxacin release from the cross-linked membrane. Results: FTIR analysis showed the characteristic peaks of gelatin, PGS, and ciprofloxacin without any added peaks after the crosslinking process. SEM images revealed that nanofibers' size increased during the crosslinking process and porosity was higher than 80% before and after crosslinking process. UV-visible spectrophotometry showed the proper rate of ciprofloxacin release occurred from cross-linked membrane that remaining in EDC/NHS ethanol solution for 120 min. Conclusion: The obtained results suggest that this recently developed gelatin/PGS membrane with controlled release of ciprofloxacin could be a promising biodegradable membrane for wound dressing.

  18. Silver nanoparticles embedded in zeolite membranes: release of silver ions and mechanism of antibacterial action

    Science.gov (United States)

    Nagy, Amber; Harrison, Alistair; Sabbani, Supriya; Munson, Robert S; Dutta, Prabir K; Waldman, W James

    2011-01-01

    Background The focus of this study is on the antibacterial properties of silver nanoparticles embedded within a zeolite membrane (AgNP-ZM). Methods and Results These membranes were effective in killing Escherichia coli and were bacteriostatic against methicillin-resistant Staphylococcus aureus. E. coli suspended in Luria Bertani (LB) broth and isolated from physical contact with the membrane were also killed. Elemental analysis indicated slow release of Ag+ from the AgNP-ZM into the LB broth. The E. coli killing efficiency of AgNP-ZM was found to decrease with repeated use, and this was correlated with decreased release of silver ions with each use of the support. Gene expression microarrays revealed upregulation of several antioxidant genes as well as genes coding for metal transport, metal reduction, and ATPase pumps in response to silver ions released from AgNP-ZM. Gene expression of iron transporters was reduced, and increased expression of ferrochelatase was observed. In addition, upregulation of multiple antibiotic resistance genes was demonstrated. The expression levels of multicopper oxidase, glutaredoxin, and thioredoxin decreased with each support use, reflecting the lower amounts of Ag+ released from the membrane. The antibacterial mechanism of AgNP-ZM is proposed to be related to the exhaustion of antioxidant capacity. Conclusion These results indicate that AgNP-ZM provide a novel matrix for gradual release of Ag+. PMID:21931480

  19. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xiang Wang

    2013-01-01

    Full Text Available We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  20. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    KAUST Repository

    Wang, Xiang; Li, Shunbo; Wang, Limu; Yi, Xin; Hui, Yu Sanna; Qin, Jianhua; Wen, Weijia

    2013-01-01

    We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  1. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    KAUST Repository

    Wang, Xiang

    2013-01-01

    We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  2. Controlled drug release from cross-linked κ-carrageenan/hyaluronic acid membranes.

    Science.gov (United States)

    El-Aassar, M R; El Fawal, G F; Kamoun, Elbadawy A; Fouda, Moustafa M G

    2015-01-01

    In this work, hydrogel membrane composed of; kappa carrageenan (κC) and hyaluronic acid (HA) crosslinked with epichlorohydrine is produced. The optimum condition has been established based on their water absorption properties. Tensile strength (TS) and elongation (E%) for the formed films are evaluated. The obtained films were characterized by FTIR, scanning electron microscopy (SEM) and thermal analysis. All membranes were loaded with l-carnosine as a drug model. The swelling properties and kinetics of the release of the model drug from the crosslinked hydrogel membrane were monitored in buffer medium at 37°C. The equilibrium swelling of films showed fair dependency on the high presence of HA in the hydrogel. Moreover, the cumulative release profile increased significantly and ranged from 28% to 93%, as HA increases. SEM explored that, the porosity increased by increasing HA content; consequently, drug release into the pores and channels of the membranes is facilitated. In addition, water uptake % increased as well. A slight change in TS occurred by increasing the HA% to κC, while the highest value of strain for κC membrane was 498.38% by using 3% HA. The thermal stability of the κC/HA was higher than that of HA. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Hypersonic Poration of Membranes : From Triggered Release and Encapsulation to Drug Delivery

    NARCIS (Netherlands)

    Lu, Yao

    2018-01-01

    In this thesis, hypersonic poration is introduced as a new physical method to precisely control membrane permeability for the applications of controlled release and encapsulation, and enhanced drug delivery. Bulk acoustic wave (BAW) resonators of gigahertz (GHz) frequency have been fabricated using

  4. DNA release from lipoplexes by anionic lipids: correlation with lipid mesomorphism, interfacial curvature, and membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Tarahovsky, Yury S.; Koynova, Rumiana; MacDonald, Robert C. (Northwestern)

    2010-01-18

    DNA release from lipoplexes is an essential step during lipofection and is probably a result of charge neutralization by cellular anionic lipids. As a model system to test this possibility, fluorescence resonance energy transfer between DNA and lipid covalently labeled with Cy3 and BODIPY, respectively, was used to monitor the release of DNA from lipid surfaces induced by anionic liposomes. The separation of DNA from lipid measured this way was considerably slower and less complete than that estimated with noncovalently labeled DNA, and depends on the lipid composition of both lipoplexes and anionic liposomes. This result was confirmed by centrifugal separation of released DNA and lipid. X-ray diffraction revealed a clear correlation of the DNA release capacity of the anionic lipids with the interfacial curvature of the mesomorphic structures developed when the anionic and cationic liposomes were mixed. DNA release also correlated with the rate of fusion of anionic liposomes with lipoplexes. It is concluded that the tendency to fuse and the phase preference of the mixed lipid membranes are key factors for the rate and extent of DNA release. The approach presented emphasizes the importance of the lipid composition of both lipoplexes and target membranes and suggests optimal transfection may be obtained by tailoring lipoplex composition to the lipid composition of target cells.

  5. Novel meloxicam releasing electrospun polymer/ceramic reinforced biodegradable membranes for periodontal regeneration applications

    Energy Technology Data Exchange (ETDEWEB)

    Yar, Muhammad, E-mail: drmyar@ciitlahore.edu.pk [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Farooq, Ariba [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Shahzadi, Lubna; Khan, Abdul Samad [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Mahmood, Nasir [Department of Allied Health Sciences and Chemical Pathology, Department of Human Genetics and Molecular Biology, University of Health Sciences, Lahore (Pakistan); Rauf, Abdul [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Chaudhry, Aqif Anwar [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rehman, Ihtesham ur [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Materials Science and Engineering, The Kroto Research Institute, The University of Sheffield, North Campus, Broad Lane, Sheffield S3 7HQ (United Kingdom)

    2016-07-01

    Periodontal disease is associated with the destruction of periodontal tissues, along with other disorders/problems including inflammation of tissues and severe pain. This paper reports the synthesis of meloxicam (MX) immobilized biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) based electrospun (e-spun) fibers and films. Electrospinning was employed to produce drug loaded fibrous mats, whereas films were generated by solvent casting method. In-vitro drug release from materials containing varying concentrations of MX revealed that the scaffolds containing higher amount of drug showed comparatively faster release. During initial first few hours fast release was noted from membranes and films; however after around 5 h sustained release was achieved. The hydrogels showed good swelling property, which is highly desired for soft tissue engineered implants. To investigate the biocompatibility of our synthesized materials, VERO cells (epithelial cells) were selected and cell culture results showed that these all materials were non-cytotoxic and also these cells were very well proliferated on these synthesized scaffolds. These properties along with the anti-inflammatory potential of our fabricated materials suggest their effective utilization in periodontital treatments. - Highlights: • NSAIDs releasing scaffolds for periodontal regeneration applications • Meloxicam immobilized biodegradable nanocomposite electrospun membranes and films • Good swelling properties • Controlled drug release • VERO cells were very well proliferated and synthesized materials were found to be non-cytotoxic.

  6. Novel meloxicam releasing electrospun polymer/ceramic reinforced biodegradable membranes for periodontal regeneration applications

    International Nuclear Information System (INIS)

    Yar, Muhammad; Farooq, Ariba; Shahzadi, Lubna; Khan, Abdul Samad; Mahmood, Nasir; Rauf, Abdul; Chaudhry, Aqif Anwar; Rehman, Ihtesham ur

    2016-01-01

    Periodontal disease is associated with the destruction of periodontal tissues, along with other disorders/problems including inflammation of tissues and severe pain. This paper reports the synthesis of meloxicam (MX) immobilized biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) based electrospun (e-spun) fibers and films. Electrospinning was employed to produce drug loaded fibrous mats, whereas films were generated by solvent casting method. In-vitro drug release from materials containing varying concentrations of MX revealed that the scaffolds containing higher amount of drug showed comparatively faster release. During initial first few hours fast release was noted from membranes and films; however after around 5 h sustained release was achieved. The hydrogels showed good swelling property, which is highly desired for soft tissue engineered implants. To investigate the biocompatibility of our synthesized materials, VERO cells (epithelial cells) were selected and cell culture results showed that these all materials were non-cytotoxic and also these cells were very well proliferated on these synthesized scaffolds. These properties along with the anti-inflammatory potential of our fabricated materials suggest their effective utilization in periodontital treatments. - Highlights: • NSAIDs releasing scaffolds for periodontal regeneration applications • Meloxicam immobilized biodegradable nanocomposite electrospun membranes and films • Good swelling properties • Controlled drug release • VERO cells were very well proliferated and synthesized materials were found to be non-cytotoxic.

  7. Immunomodulatory role for membrane vesicles released by THP-1 macrophages and respiratory pathogens during macrophage infection.

    Science.gov (United States)

    Volgers, Charlotte; Benedikter, Birke J; Grauls, Gert E; Savelkoul, Paul H M; Stassen, Frank R M

    2017-11-13

    During infection, inflammation is partially driven by the release of mediators which facilitate intercellular communication. Amongst these mediators are small membrane vesicles (MVs) that can be released by both host cells and Gram-negative and -positive bacteria. Bacterial membrane vesicles are known to exert immuno-modulatory and -stimulatory actions. Moreover, it has been proposed that host cell-derived vesicles, released during infection, also have immunostimulatory properties. In this study, we assessed the release and activity of host cell-derived and bacterial MVs during the first hours following infection of THP-1 macrophages with the common respiratory pathogens non-typeable Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa. Using a combination of flow cytometry, tunable resistive pulse sensing (TRPS)-based analysis and electron microscopy, we demonstrated that the release of MVs occurs by both host cells and bacteria during infection. MVs released during infection and bacterial culture were found to induce a strong pro-inflammatory response by naive THP-1 macrophages. Yet, these MVs were also found to induce tolerance of host cells to secondary immunogenic stimuli and to enhance bacterial adherence and the number of intracellular bacteria. Bacterial MVs may play a dual role during infection, as they can both trigger and dampen immune responses thereby contributing to immune defence and bacterial survival.

  8. Immobilization and release study of a red alga extract in hydrogel membranes

    International Nuclear Information System (INIS)

    Amaral, Renata Hage

    2009-01-01

    In pharmaceutical technology hydrogel is the most used among the polymeric matrices due to its wide application and functionality, primarily in drug delivery system. In view of the large advance innovations in cosmetic products, both through the introduction of new active agents as the matrices used for its controlled release, the objective of this study was to evaluate the release and immobilization of a natural active agent, the Arct'Alg in hydrogel membranes to obtain a release device for cosmetics. Arct'Alg is an aqueous extract which has excellent anti-oxidant, lipolytic, anti-inflammatory and cytostimulant action. Study on mechanical and physical-chemical properties and biocompatibility in vitro of hydrogel membranes of poly(vinyl-2- pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) obtained by ionizing radiation crosslinking have been performed. The physical-chemical characterization of polymeric matrices was carried out by gel fraction and swelling tests and biocompatibility by in vitro test of cytotoxicity by using the technique of neutral red incorporation. In the gel fraction test, both the PVP and PVA hydrogel showed a high crosslinking degree. The PVP hydrogel showed a greater percentage of swelling in relation to PVA and the cytotoxicity test of the hydrogels showed non-toxicity effect. The cytostimulation property of Arct'Alg was verified by the cytostimulation test with rabbit skin cells, it was showed an increase at about 50% of the cells when in contact with 0,5% of active agent. The hydrogel membranes prepared with 3% of Arct'Alg were subjected to the release test in an incubator at 37 degree C and aliquots collected during the test were quantified by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that the PVP hydrogel membranes released about 50% of Arct'Alg incorporated and the PVA hydrogel membranes at about 30%. In the cytostimulation test of released Arct'Alg, the PVP device showed an

  9. Ion channel activity of membrane vesicles released from sea urchin sperm during the acrosome reaction

    International Nuclear Information System (INIS)

    Schulz, Joseph R.; Vega-Beltran, Jose L. de la; Beltran, Carmen; Vacquier, Victor D.; Darszon, Alberto

    2004-01-01

    The sperm acrosome reaction (AR) involves ion channel activation. In sea urchin sperm, the AR requires Ca 2+ and Na + influx and K + and H + efflux. During the AR, the plasma membrane fuses with the acrosomal vesicle membrane forming hybrid membrane vesicles that are released from sperm into the medium. This paper reports the isolation and preliminary characterization of these acrosome reaction vesicles (ARVs), using synaptosome-associated protein of 25 kDa (SNAP-25) as a marker. Isolated ARVs have a unique protein composition. The exocytosis regulatory proteins vesicle-associated membrane protein and SNAP-25 are inside ARVs, as judged by protease protection experiments, and membrane associated based on Triton X-114 partitioning. ARVs fused with planar bilayers display three main types of single channel activity. The most frequently recorded channel is cationic, weakly voltage dependent and has a low open probability that increases with negative potentials. This channel is activated by cAMP, blocked by Ba 2+ , and has a PK + /PNa + selectivity of 4.5. ARVs represent a novel membrane preparation suitable to deepen our understanding of ion channel activity in the AR and during fertilization

  10. Uptake and release protocol for assessing membrane binding and permeation by way of isothermal titration calorimetry.

    Science.gov (United States)

    Tsamaloukas, Alekos D; Keller, Sandro; Heerklotz, Heiko

    2007-01-01

    The activity of many biomolecules and drugs crucially depends on whether they bind to biological membranes and whether they translocate to the opposite lipid leaflet and trans aqueous compartment. A general strategy to measure membrane binding and permeation is the uptake and release assay, which compares two apparent equilibrium situations established either by the addition or by the extraction of the solute of interest. Only solutes that permeate the membrane sufficiently fast do not show any dependence on the history of sample preparation. This strategy can be pursued for virtually all membrane-binding solutes, using any method suitable for detecting binding. Here, we present in detail one example that is particularly well developed, namely the nonspecific membrane partitioning and flip-flop of small, nonionic solutes as characterized by isothermal titration calorimetry. A complete set of experiments, including all sample preparation procedures, can typically be accomplished within 2 days. Analogous protocols for studying charged solutes, virtually water-insoluble, hydrophobic compounds or specific ligands are also considered.

  11. Electrodeposition to construct free-standing chitosan/layered double hydroxides hydro-membrane for electrically triggered protein release.

    Science.gov (United States)

    Zhao, Pengkun; Zhao, Yanan; Xiao, Ling; Deng, Hongbing; Du, Yumin; Chen, Yun; Shi, Xiaowen

    2017-10-01

    In this study, we report the electrodeposition of a chitosan/layered double hydroxides (LDHs) hydro-membrane for protein release triggered by an electrical signal. The electrodeposition was performed in a chitosan and insulin loaded LDHs suspension in the absence of salt. A free-standing chitosan/LDHs hydro-membrane was generated on the electrode with improved mechanical properties, which is dramatically different from the weak hydrogel deposited in the presence of salt. The amount of LDHs in the hydro-membrane affects the optical transmittance and multilayered structure of the hybrid membrane. Compared to the weak chitosan/LDHs hydrogel, the hydro-membrane has a higher insulin loading capacity and the release of insulin is relatively slow. By biasing electrical potentials to the hydro-membrane, the release behavior of insulin can be adjusted accordingly. In addition, the chitosan/LDHs hydro-membrane showed no toxicity to cells. Our results provide a facile method to construct a chitosan/LDHs hybrid multilayered hydro-membrane and suggest the great potential of the hydro-membrane in controlled protein release. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Outer Mitochondrial Membrane Localization of Apoptosis-Inducing Factor: Mechanistic Implications for Release

    Directory of Open Access Journals (Sweden)

    Seong-Woon Yu

    2009-10-01

    Full Text Available Poly(ADP-ribose polymerase-1-dependent cell death (known as parthanatos plays a pivotal role in many clinically important events including ischaemia/reperfusion injury and glutamate excitotoxicity. A recent study by us has shown that uncleaved AIF (apoptosis-inducing factor, but not calpain-hydrolysed truncated-AIF, was rapidly released from the mitochondria during parthanatos, implicating a second pool of AIF that might be present in brain mitochondria contributing to the rapid release. In the present study, a novel AIF pool is revealed in brain mitochondria by multiple biochemical analyses. Approx. 30% of AIF loosely associates with the outer mitochondrial membrane on the cytosolic side, in addition to its main localization in the mitochondrial intermembrane space attached to the inner membrane. Immunogold electron microscopic analysis of mouse brain further supports AIF association with the outer, as well as the inner, mitochondrial membrane in vivo. In line with these observations, approx. 20% of uncleaved AIF rapidly translocates to the nucleus and functionally causes neuronal death upon NMDA (N-methyl-d-aspartate treatment. In the present study we show for the first time a second pool of AIF in brain mitochondria and demonstrate that this pool does not require cleavage and that it contributes to the rapid release of AIF. Moreover, these results suggest that this outer mitochondrial pool of AIF is sufficient to cause cell death during parthanatos. Interfering with the release of this outer mitochondrial pool of AIF during cell injury paradigms that use parthanatos hold particular promise for novel therapies to treat neurological disorders.

  13. Interpenetrating network hydrogel membranes of sodium alginate and poly(vinyl alcohol) for controlled release of prazosin hydrochloride through skin.

    Science.gov (United States)

    Kulkarni, Raghavendra V; Sreedhar, V; Mutalik, Srinivas; Setty, C Mallikarjun; Sa, Biswanath

    2010-11-01

    Interpenetrating network (IPN) hydrogel membranes of sodium alginate (SA) and poly(vinyl alcohol) (PVA) were prepared by solvent casting method for transdermal delivery of an anti-hypertensive drug, prazosin hydrochloride. The prepared membranes were thin, flexible and smooth. The X-ray diffraction studies indicated the amorphous dispersion of drug in the membranes. Differential scanning calorimetric analysis confirmed the IPN formation and suggests that the membrane stiffness increases with increased concentration of glutaraldehyde (GA) in the membranes. All the membranes were permeable to water vapors depending upon the extent of cross-linking. The in vitro drug release study was performed through excised rat abdominal skin; drug release depends on the concentrations of GA in membranes. The IPN membranes extended drug release up to 24 h, while SA and PVA membranes discharged the drug quickly. The primary skin irritation and skin histopathology study indicated that the prepared IPN membranes were less irritant and safe for skin application. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. New type of chitosan/2-hydroxypropyl-β-cyclodextrin composite membrane for gallic acid encapsulation and controlled release.

    Science.gov (United States)

    Paun, Gabriela; Neagu, Elena; Tache, Andreia; Radu, G L

    2014-01-01

    A new type of chitosan/2-hydroxypropyl-β-cyclodextrin composite membrane have been developed for the encapsulation and controlled release of gallic acid. The morphology of the composite membrane was investigated by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), whereas swelling gallic acid and release properties were investigated by UV-visible spectroscopy. The release behavior with pH changes was also explored. The composite membrane based on chitosan/2-hydroxypropyl-β-cyclodextrin with gallic acid included showed improved antioxidant capacities compared to plain chitosan membrane. The information obtained in this study will facilitate the design and preparation of composite membrane based on chitosan and could open a wide range of applications, particularly its use as an antioxidant in food, food packaging, biomedical (biodegradable soft porous scaffolds for enhance the surrounding tissue regeneration), pharmaceutical and cosmetics industries.

  15. DIDS prevents ischemic membrane degradation in cultured hippocampal neurons by inhibiting matrix metalloproteinase release.

    Directory of Open Access Journals (Sweden)

    Matthew E Pamenter

    Full Text Available During stroke, cells in the infarct core exhibit rapid failure of their permeability barriers, which releases ions and inflammatory molecules that are deleterious to nearby tissue (the penumbra. Plasma membrane degradation is key to penumbral spread and is mediated by matrix metalloproteinases (MMPs, which are released via vesicular exocytosis into the extracellular fluid in response to stress. DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid preserves membrane integrity in neurons challenged with an in vitro ischemic penumbral mimic (ischemic solution: IS and we asked whether this action was mediated via inhibition of MMP activity. In cultured murine hippocampal neurons challenged with IS, intracellular proMMP-2 and -9 expression increased 4-10 fold and extracellular latent and active MMP isoform expression increased 2-22 fold. MMP-mediated extracellular gelatinolytic activity increased ∼20-50 fold, causing detachment of 32.1±4.5% of cells from the matrix and extensive plasma membrane degradation (>60% of cells took up vital dyes and >60% of plasma membranes were fragmented or blebbed. DIDS abolished cellular detachment and membrane degradation in neurons and the pathology-induced extracellular expression of latent and active MMPs. DIDS similarly inhibited extracellular MMP expression and cellular detachment induced by the pro-apoptotic agent staurosporine or the general proteinase agonist 4-aminophenylmercuric acetate (APMA. Conversely, DIDS-treatment did not impair stress-induced intracellular proMMP production, nor the intracellular cleavage of proMMP-2 to the active form, suggesting DIDS interferes with the vesicular extrusion of MMPs rather than directly inhibiting proteinase expression or activation. In support of this hypothesis, an antagonist of the V-type vesicular ATPase also inhibited extracellular MMP expression to a similar degree as DIDS. In addition, in a proteinase-independent model of vesicular exocytosis, DIDS

  16. Multilayer Membranes of Glycosaminoglycans and Collagen I Biomaterials Modulate the Function and Microvesicle Release of Endothelial Progenitor Cells.

    Science.gov (United States)

    Dai, Bingyan; Pan, Qunwen; Li, Zhanghua; Zhao, Mingyan; Liao, Xiaorong; Wu, Keng; Ma, Xiaotang

    2016-01-01

    Multilayer composite membrane of biomaterials can increase the function of adipose stem cells or osteoprogenitor cells. Recent evidence indicates endothelial progenitor cells (EPCs) and EPCs released microvesicles (MVs) play important roles in angiogenesis and vascular repair. Here, we investigated the effects of biomaterial multilayer membranes of hyaluronic acid (HA) or chondroitin sulfate (CS) and Collagen I (Col I) on the functions and MVs release of EPCs. Layer-by-layer (LBL) technology was applied to construct the multilayer composite membranes. Four types of the membranes constructed by adsorbing either HA or CS and Col I alternatively with different top layers were studied. The results showed that all four types of multilayer composite membranes could promote EPCs proliferation and migration and inhibit cell senility, apoptosis, and the expression of activated caspase-3. Interestingly, these biomaterials increased the release and the miR-126 level of EPCs-MVs. Moreover, the CS-Col I membrane with CS on the top layer showed the most effects on promoting EPCs proliferation, EPCs-MV release, and miR-126 level in EPCs-MVs. In conclusion, HA/CS and Collagen I composed multilayer composite membranes can promote EPCs functions and release of miR-126 riched EPCs-MVs, which provides a novel strategy for tissue repair treatment.

  17. Inhibition of basophil histamine release by gangliosides. Further studies on the significance of cell membrane sialic acid in the histamine release process

    DEFF Research Database (Denmark)

    Jensen, C; Norn, S; Thastrup, Ole

    1987-01-01

    with the glucolipid mixture increased the sialic acid content of the cells, and this increase was attributed to an insertion of gangliosides into the cell membrane. The inhibition of histamine release was abolished by increasing the calcium concentration, which substantiates our previous findings that cell membrane......Histamine release from human basophils was inhibited by preincubation of the cells with a glucolipid mixture containing sialic acid-containing gangliosides. This was true for histamine release induced by anti-IgE, Concanavalin A and the calcium ionophore A23187, whereas the release induced by S....... aureus Wood 46 was not affected. It was demonstrated that the inhibitory capacity of the glucolipid mixture could be attributed to the content of gangliosides, since no inhibition was obtained with cerebrosides or with gangliosides from which sialic acid was removed. Preincubation of the cells...

  18. Influence of nano-fiber membranes on the silver ions released from hollow fibers containing silver particles

    Directory of Open Access Journals (Sweden)

    Li Huigai

    2016-01-01

    Full Text Available Polyether sulfone was dissolved into dimethylacetamide with the concentration of 20% to prepare a uniform solution for fabrication of nanofiber membranes by bubble electrospinning technique. Morphologies of the nanofiber film were carried out with a scanning electron microscope. The influence on the silver ions escaped from hollow fiber loaded with silver particles was exerted by using different release liquid. The water molecular clusters obtained from the nanofiber membranes filter can slow down the release of silver ions. However, the effect of slowing was weakened with the time increasing. In the end, the trend of change is gradually consistent with the trend of release of silver ions in the deionized water.

  19. Drug Release from ß-Cyclodextrin Complexes and Drug Transfer into Model Membranes Studied by Affinity Capillary Electrophoresis.

    Science.gov (United States)

    Darwish, Kinda A; Mrestani, Yahya; Rüttinger, Hans-Hermann; Neubert, Reinhard H H

    2016-05-01

    Is to characterize the drug release from the ß-cyclodextrin (ß-CD) cavity and the drug transfer into model membranes by affinity capillary electrophoresis. Phospholipid liposomes with and without cholesterol were used to mimic the natural biological membrane. The interaction of cationic and anionic drugs with ß-CD and the interaction of the drugs with liposomes were detected separately by measuring the drug mobility in ß-CD containing buffer and liposome containing buffer; respectively. Moreover, the kinetics of drug release from ß-CD and its transfer into liposomes with or without cholesterol was studied by investigation of changes in the migration behaviours of the drugs in samples, contained drug, ß-CD and liposome, at 1:1:1 molar ratio at different time intervals; zero time, 30 min, 1, 2, 4, 6, 8, 10 and 24 h. Lipophilic drugs such as propranolol and ibuprofen were chosen for this study, because they form complexes with ß-CD. The mobility of the both drug liposome mixtures changed with time to a final state. For samples of liposomal membranes with cholesterol the final state was faster reached than without cholesterol. The study confirmed that the drug release from the CD cavity and its transfer into the model membrane was more enhanced by the competitive displacement of the drug from the ß-CD cavity by cholesterol, the membrane component. The ACE method here developed can be used to optimize the drug release from CD complexes and the drug transfer into model membranes.

  20. Characterization of a poly(ether urethane)-based controlled release membrane system for delivery of ketoprofen

    International Nuclear Information System (INIS)

    Macocinschi, Doina; Filip, Daniela; Vlad, Stelian; Oprea, Ana Maria; Gafitanu, Carmen Anatolia

    2012-01-01

    Highlights: ► Ketoprofen incorporation in poly(ether urethane) microporous membrane. ► Moisture sorption properties of as-cast membrane. ► Drug release mechanisms in function of pH and composition of membranes. - Abstract: A poly(ether urethane) based on polytetrahydrofuran containing hydroxypropyl cellulose for biomedical applications was tested for its biocompatibility. Ketoprofen was incorporated (3% and 6%) in the polyurethane matrix as an anti-inflammatory drug. Kinetic and drug release mechanisms were studied. The pore size and pore size distribution of the polyurethane membranes were investigated by scanning electron microscopy. Surface tension characteristics as well as moisture sorption properties such as diffusion coefficients and equilibrium moisture contents of the membrane material were studied. It was found that kinetics and release mechanisms are in function of medium pH, composition of polymer–drug system, pore morphology and pore size distribution. Prolonged nature of release of ketoprofen is assured by low amount of drug in polyurethane membrane and physiological pH.

  1. Effects of membrane composition on release of model hydrophilic compound from osmotic delivery systems.

    Science.gov (United States)

    Ozdemir, N; Ozalp, Y; Ozkan, Y

    2000-01-01

    In this study, the effects of surface-active agents in different types and concentrations, added into the coating solution, on release of model hydrophilic compound have been examined. For this purpose, the tablets, prepared with the use of methylene blue as a model substance, were coated by spray coating technique with cellulose acetate solution containing polyethylene glycol 400 as a plasticizer. In addition, cetylpyridinium chloride as cationic surface-active agent and sodium lauryl sulphate as anionic surface-active agent were added into coating solution in different concentrations. After creating a delivery orifice by a microdrill on the tablets, release of model hydrophilic compound was tested by the USP paddle method. The data obtained were evaluated according to the different kinetics and the mechanism of release from the preparations was examined. The surface properties of the coating material were investigated by scanning electron microscope taken before and after the contact with medium fluid, as well as the mechanical properties by tensile tests. In conclusion, it has been found that the cationic surface active agent, cetylpyridinium chloride reduced the lag time, observed during the release of model hydrophilic compound, as a result of its enhancing effect on wettability of tablets by reducing the contact angle between the medium fluid and the coating material. On the other hand, the anionic surface active agent, sodium lauryl sulphate has been inactivated possibly due to the interaction with model hydrophilic compound that has cationic properties and/or substances contained in membrane composition; thus, the lag time has not decreased and furthermore, a significant decrease in the delivery rate of model hydrophilic compound has been observed.

  2. Evaluation of the release behavior of the dexamethasone embedded in polycarbonate polyurethane membranes: an in vitro study

    International Nuclear Information System (INIS)

    Kim, Dong Hyun; Kang, Sung Gwon; Lee, Chul Gab; Park, Sang Soo; Lee, Don Haeng; Lee, Gyu Baek; Song, Ho Young

    2003-01-01

    To evaluate the release behavior of dexamethasone embedded in a polycarbonate polyurethane membrane. Both water-soluble and water-insoluble dexamethasone were tested, and the release behavior of five water-insoluble dexamethasone films of different thickness (78 to 211 μm) was also evaluated. The amount of dexamethasone used was 10% of the total weight of the polyurethan film mass. Each film was placed in a centrifuge tube containing 25 ml of 0.1-M neutral phosphate buffer, and the tubes were placed in a shaking incubator to quantify the amount of drug released into the buffer, absorption spectroscopy (λ max=242 nm) was employed. In the test involving water-soluble dexamethasone, 60%, of the drug was released during the first two hours of the study. Films containing water-insoluble dexamethasone, on the other hand, released 40%, 60% and 75% of the dexamethasone in one, three and seven days, respectively. Both types of film maintained low-dose drug release for 28 days. When release behavior was compared between water-insoluble films of different thickness, thicker film showed less initial burst and more sustained release. Dexamethasone release behavior varies according to drug solubility and membrane thickness, and may thus be conrolled

  3. Shipment of a photodynamic therapy agent into model membrane and its controlled release: A photophysical approach.

    Science.gov (United States)

    Karar, Monaj; Paul, Suvendu; Mallick, Arabinda; Majumdar, Tapas

    2018-01-01

    Harmine, an efficient cancer cell photosensitizer (PS), emits intense violet color when it is incorporated in well established self assembly based drug carrier formed by cationic surfactants of identical positive charge of head group but varying chain length, namely, dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). Micelle entrapped drug emits in the UV region when it interacts with non-toxic β-cyclodextrin (β-CD). Inspired by these unique fluorescence/structural switching properties of the anticancer drug, in the present work we have monitored the interplay of the drug between micelles and non-toxic β-CDs. We have observed that the model membranes formed by micelles differing in their hydrophobic chain length interact with the drug differently. Variation in the surfactant chain length plays an important role for structural switching i.e. in choosing a particular structural form of the drug that will be finally presented to their targets. The present study shows that in case of necessity, the bound drug molecule can be removed from its binding site in a controlled manner by the use of non-toxic β-CD and it is exploited to serve a significant purpose for the removal of excess/unused adsorbed drugs from the model cell membranes. We believe this kind of β-CD driven translocation of drugs monitored by fluorescence switching may find possible applications in controlled release of the drug inside cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Preparation and evaluation of tamsulosin hydrochloride sustained-release pellets modified by two-layered membrane techniques

    Directory of Open Access Journals (Sweden)

    Jingmin Wang

    2015-02-01

    Full Text Available The aim of the present study was to develop tamsulosin hydrochloride sustained-release pellets using two-layered membrane techniques. Centrifugal granulator and fluidized-bed coater were employed to prepare drug-loaded pellets and to employ two-layered membrane coating respectively. The prepared pellets were evaluated for physicochemical characterization, subjected to differential scanning calorimetry (DSC and in vitro release of different pH. Different release models and scanning electron microscopy (SEM were utilized to analyze the release mechanism of Harnual® and home-made pellets. By comparing the dissolution profiles, the ratio and coating weight gain of Eudragit® NE30D and Eudragit® L30D55 which constitute the inside membrane were identified as 18:1 and 10%–11%. The coating amount of outside membrane containing Eudragit® L30D55 was determined to be 0.8%. The similarity factors (f2 of home-made capsule and commercially available product (Harnual® were above 50 in different dissolution media. DSC studies confirmed that drug and excipients had good compatibility and SEM photographs showed the similarities and differences of coating surface between Harnual® and self-made pellets before and after dissolution. According to Ritger-Peppas model, the two dosage form had different release mechanism.

  5. Vesicle-mediated transport and release of CCL21 in endangered neurons : A possible explanation for microglia activation remote from a primary lesion

    NARCIS (Netherlands)

    de Jong, EK; Dijkstra, IM; Hensens, M; Brouwer, N; van Amerongen, M; Liem, RSB; Boddeke, HWGM; Biber, K

    2005-01-01

    Whenever neurons in the CNS are injured, microglia become activated. In addition to local activation, microglia remote from the primary lesion site are stimulated. Because this so-called secondary activation of microglia is instrumental for long-term changes after neuronal injury, it is important to

  6. Loss of covalently linked lipid as the mechanism for radiation-induced release of membrane-bound polysaccharide and exonuclease from Micrococcus radiodurans

    International Nuclear Information System (INIS)

    Mitchel, R.E.J.

    1981-01-01

    The mechanism of γ-radiation-induced release of polysaccharide and exonuclease from the midwall membrane of Micrococcus radiodurans has been examined. These two components appear to be released independently, but by very similar processes. Direct analysis of radiation-released polysaccharide indicated the absence of an alkali-labile neutral lipid normally present in the native material. Radiation-induced release therefore probably results from the radiolytic cleavage of a covalently linked lipid which normally serves to anchor these substances to the membrane. The absence of a natural membrane-bound carotenoid had no effect on the rate of release of these components. Likewise, the absence of exonuclease in an exonuclease minus mutant did not influence the release of polysaccharide. It is suggested that the major pathway of radical transfer from the initiating .OH and culminating in the cleavage of the neutral lipid anchor may not be via the membrane

  7. Design of poly(vinylidene fluoride)-g-p(hydroxyethyl methacrylate-co-N-isopropylacrylamide) membrane via surface modification for enhanced fouling resistance and release property

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Guili [Nanyang Environment and Water Research Institute, Interdisciplinary Graduate School, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141 (Singapore); Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141 (Singapore); School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Chen, Wei Ning, E-mail: WNChen@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore)

    2017-03-15

    Highlights: • PVDF modified membranes were designed by grafting PNIPAAm, PHEMA and their copolymer. • Fouling resistance and release property of membrane were both improved after modification. • Bacterial attachment and detachment were investigated to evaluate fouling release property. • Improvement of the antifouling property was justified by surface property analysis. • The copolymer modified membrane exhibited higher performance to release foulant. - Abstract: Thermo-sensitive polymer poly(N-isopropylacrylamide) (PNIPAAm), hydrophilic polymer poly(hydroxyethyl methacrylate) (PHEMA) and copolymer p(hydroxyethyl methacrylate-co-N-isopropylacrylamide) [P(HEMA-co-NIPAAm)] were synthesized onto poly(vinylidene fluoride) (PVDF) membrane via atom transfer radical polymerization (ATRP) in order to improve not only fouling resistance but also fouling release property. The physicochemical properties of membranes including hydrophilicity, morphology and roughness were examined by contact angle analyzer, scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. The antifouling property of membranes was improved remarkably after surface modification according to protein and bacterial adhesion testing, and filtration experiment. Minimum protein adsorption and bacterial adhesion were both obtained on PVDF-g-P(HEMA-co-NIPAAm) membrane, with reduction by 44% and 71% respectively compared to the pristine membrane. The minimum bacterial cells after detachment at 25 °C were observed on the PVDF-g-P(HEMA-co-NIPAAm) membrane with the detachment rate of 77%, indicating high fouling release property. The filtration testing indicated that the copolymer modified membrane exhibited high resistance to protein fouling and the foulant on the surface was released and removed easily by washing, suggesting high fouling release and easy-cleaning capacity. This study provides useful insight in the combined “fouling resistance” and “fouling release

  8. Design of poly(vinylidene fluoride)-g-p(hydroxyethyl methacrylate-co-N-isopropylacrylamide) membrane via surface modification for enhanced fouling resistance and release property

    International Nuclear Information System (INIS)

    Zhao, Guili; Chen, Wei Ning

    2017-01-01

    Highlights: • PVDF modified membranes were designed by grafting PNIPAAm, PHEMA and their copolymer. • Fouling resistance and release property of membrane were both improved after modification. • Bacterial attachment and detachment were investigated to evaluate fouling release property. • Improvement of the antifouling property was justified by surface property analysis. • The copolymer modified membrane exhibited higher performance to release foulant. - Abstract: Thermo-sensitive polymer poly(N-isopropylacrylamide) (PNIPAAm), hydrophilic polymer poly(hydroxyethyl methacrylate) (PHEMA) and copolymer p(hydroxyethyl methacrylate-co-N-isopropylacrylamide) [P(HEMA-co-NIPAAm)] were synthesized onto poly(vinylidene fluoride) (PVDF) membrane via atom transfer radical polymerization (ATRP) in order to improve not only fouling resistance but also fouling release property. The physicochemical properties of membranes including hydrophilicity, morphology and roughness were examined by contact angle analyzer, scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. The antifouling property of membranes was improved remarkably after surface modification according to protein and bacterial adhesion testing, and filtration experiment. Minimum protein adsorption and bacterial adhesion were both obtained on PVDF-g-P(HEMA-co-NIPAAm) membrane, with reduction by 44% and 71% respectively compared to the pristine membrane. The minimum bacterial cells after detachment at 25 °C were observed on the PVDF-g-P(HEMA-co-NIPAAm) membrane with the detachment rate of 77%, indicating high fouling release property. The filtration testing indicated that the copolymer modified membrane exhibited high resistance to protein fouling and the foulant on the surface was released and removed easily by washing, suggesting high fouling release and easy-cleaning capacity. This study provides useful insight in the combined “fouling resistance” and “fouling release

  9. Release of LHRH-activity from human fetal membranes upon exposure to PGE/sub 2/, oxytocin and isoproterenol

    Energy Technology Data Exchange (ETDEWEB)

    Poisner, A.M.; Poisner, R.; Becca, C.R.; Conn, P.M.

    1986-03-01

    The authors have previously reported that superfused chorion laeve (fetal membranes) release LHRH-like immunoreactivity upon exposure to angiotensin II. They have now studied the effects of other agonists on the release of LHRH-activity and something of its chemical nature. Fetal membranes were obtained from placentas delivered by cesarean section, the amnion stripped from the chorion, and the chorion superfused in an Amicon thin-channel device with the maternal surface facing up. The whole device was submerged in a 37 C water bath and perfused with a modified Locke's solution at 0.4 - 1.0 ml/min. LHRH-activity was measured by radioimmunoassay using three different antisera against LHRH. The release of LHRH-activity was stimulated by 6-10 min exposure to PGE/sub 2/, oxytocin, and isoproterenol. Extracts of chorion were studied using gel filtration on Sephacryl S-200 and ultrafiltration with Amicon PM-10 filters. The bulk of the LHRH-activity appeared as a higher molecular weight form (about 70,000 daltons). Since oxytocin has been reported to release PGE/sub 2/ from chorion, it may release LHRH-activity by virtue of liberating endogenous PGE/sub 2/. The chemical nature of the LHRH-activity is presently under investigation.

  10. Genetic Analysis of the Mode of Interplay between an ATPase Subunit and Membrane Subunits of the Lipoprotein-Releasing ATP-Binding Cassette Transporter LolCDE†

    OpenAIRE

    Ito, Yasuko; Matsuzawa, Hitomi; Matsuyama, Shin-ichi; Narita, Shin-ichiro; Tokuda, Hajime

    2006-01-01

    The LolCDE complex, an ATP-binding cassette (ABC) transporter, releases lipoproteins from the inner membrane, thereby initiating lipoprotein sorting to the outer membrane of Escherichia coli. The LolCDE complex is composed of two copies of an ATPase subunit, LolD, and one copy each of integral membrane subunits LolC and LolE. LolD hydrolyzes ATP on the cytoplasmic side of the inner membrane, while LolC and/or LolE recognize and release lipoproteins anchored to the periplasmic leaflet of the i...

  11. Binding free energy and counterion release for adsorption of the antimicrobial peptide lactoferricin B on a POPG membrane

    Science.gov (United States)

    Tolokh, Igor S.; Vivcharuk, Victor; Tomberli, Bruno; Gray, C. G.

    2009-09-01

    Molecular dynamics (MD) simulations are used to study the interaction of an anionic palmitoyl-oleoyl-phosphatidylglycerol (POPG) bilayer with the cationic antimicrobial peptide bovine lactoferricin (LFCinB) in a 100 mM NaCl solution at 310 K. The interaction of LFCinB with a POPG bilayer is employed as a model system for studying the details of membrane adsorption selectivity of cationic antimicrobial peptides. Seventy eight 4 ns MD production run trajectories of the equilibrated system, with six restrained orientations of LFCinB at 13 different separations from the POPG membrane, are generated to determine the free energy profile for the peptide as a function of the distance between LFCinB and the membrane surface. To calculate the profile for this relatively large system, a variant of constrained MD and thermodynamic integration is used. A simplified method for relating the free energy profile to the LFCinB-POPG membrane binding constant is employed to predict a free energy of adsorption of -5.4±1.3kcal/mol and a corresponding maximum adsorption binding force of about 58 pN. We analyze the results using Poisson-Boltzmann theory. We find the peptide-membrane attraction to be dominated by the entropy increase due to the release of counterions and polarized water from the region between the charged membrane and peptide, as the two approach each other. We contrast these results with those found earlier for adsorption of LFCinB on the mammalianlike palmitoyl-oleoyl-phosphatidylcholine membrane.

  12. Novel flower-shaped albumin particles as controlled-release carriers for drugs to penetrate the round-window membrane

    Directory of Open Access Journals (Sweden)

    Yu Z

    2014-07-01

    Full Text Available Zhan Yu,1,* Min Yu,2,* Zhimin Zhou,3 Zhibao Zhang,3 Bo Du,3 Qingqing Xiong3 1Second Artillery General Hospital, Beijing, 2Department of Cell Biology, Key Laboratory of Cell Biology, Ministry of Public Health, College of Basic Medicine, China Medical University, Shenyang, 3Institute of Biomedical Engineering, Chinese Academy of Medical Sciences, Peking Union Medical College, Key Laboratory of Biomedical Material of Tianjin, Tianjin, People’s Republic of China *These authors contributed equallyto this work Abstract: Controlled-release carriers for local drug delivery have attracted increasing attention for inner-ear treatment recently. In this paper, flower-shaped bovine serum albumin (FBSA particles were prepared by a modified desolvation method followed by glutaraldehyde or heat denaturation. The size of the FBSA particles varied from 10 µm to 100 µm, and most were 50–80 µm. Heat-denatured FBSA particles have good cytocompatibility with a prolonged survival time for L929 cells. The FBSA particles were utilized as carriers to investigate the release behaviors of the model drug – rhodamine B. Rhodamine B showed a sustained-release effect and penetrated the round-window membrane of guinea pigs. We also confirmed the attachment of FBSA particles onto the round-window membrane by microscopy. The FBSA particles, with good biocompatibility, drug-loading capacity, adhesive capability, and biodegradability, may have potential applications in the field of local drug delivery for inner-ear disease treatment. Keywords: bovine serum albumin (BSA, controlled release, local delivery, round-window membrane

  13. Lack of Outer Membrane Protein A Enhances the Release of Outer Membrane Vesicles and Survival of Vibrio cholerae and Suppresses Viability of Acanthamoeba castellanii

    Directory of Open Access Journals (Sweden)

    Soni Priya Valeru

    2014-01-01

    Full Text Available Vibrio cholerae, the causative agent of the diarrhoeal disease cholera, survives in aquatic environments. The bacterium has developed a survival strategy to grow and survive inside Acanthamoeba castellanii. It has been shown that V. cholerae expresses outer membrane proteins as virulence factors playing a role in the adherence to interacted host cells. This study examined the role of outer membrane protein A (OmpA and outer membrane vesicles (OMVs in survival of V. cholerae alone and during its interaction with A. castellanii. The results showed that an OmpA mutant of V. cholerae survived longer than wild-type V. cholerae when cultivated alone. Cocultivation with A. castellanii enhanced the survival of both bacterial strains and OmpA protein exhibited no effect on attachment, engulfment, and survival inside the amoebae. However, cocultivation of the OmpA mutant of V. cholerae decreased the viability of A. castellanii and this bacterial strain released more OMVs than wild-type V. cholerae. Surprisingly, treatment of amoeba cells with OMVs isolated from the OmpA mutant significantly decreased viable counts of the amoeba cells. In conclusion, the results might highlight a regulating rule for OmpA in survival of V. cholerae and OMVs as a potent virulence factor for this bacterium towards eukaryotes in the environment.

  14. Disruption of lolCDE, Encoding an ATP-Binding Cassette Transporter, Is Lethal for Escherichia coli and Prevents Release of Lipoproteins from the Inner Membrane

    OpenAIRE

    Narita, Shin-ichiro; Tanaka, Kimie; Matsuyama, Shin-ichi; Tokuda, Hajime

    2002-01-01

    ATP-binding cassette transporter LolCDE was previously identified, by using reconstituted proteoliposomes, as an apparatus catalyzing the release of outer membrane-specific lipoproteins from the inner membrane of Escherichia coli. Mutations resulting in defective LolD were previously shown to be lethal for E. coli. The amino acid sequences of LolC and LolE are similar to each other, but the necessity of both proteins for lipoprotein release has not been proved. Moreover, previous reconstituti...

  15. Luteinizing hormone-releasing hormone inactivation by purified pituitary plasma membranes: effects of receptor-binding studies.

    Science.gov (United States)

    Clayton, R N; Shakespear, R A; Duncan, J A; Marshall, J C

    1979-05-01

    enhanced biological activity of the analog, therefore, may be due to its resistance to inactivation by enzymes on the pituitary cell surface. The membrane-associated inactivating enzyme could play an important role in vivo in determining the concentration of intact LHRH available at the receptor site which initiates gonadotropin release.

  16. Novel flower-shaped albumin particles as controlled-release carriers for drugs to penetrate the round-window membrane.

    Science.gov (United States)

    Yu, Zhan; Yu, Min; Zhou, Zhimin; Zhang, Zhibao; Du, Bo; Xiong, Qingqing

    2014-01-01

    Controlled-release carriers for local drug delivery have attracted increasing attention for inner-ear treatment recently. In this paper, flower-shaped bovine serum albumin (FBSA) particles were prepared by a modified desolvation method followed by glutaraldehyde or heat denaturation. The size of the FBSA particles varied from 10 μm to 100 μm, and most were 50-80 μm. Heat-denatured FBSA particles have good cytocompatibility with a prolonged survival time for L929 cells. The FBSA particles were utilized as carriers to investigate the release behaviors of the model drug - rhodamine B. Rhodamine B showed a sustained-release effect and penetrated the round-window membrane of guinea pigs. We also confirmed the attachment of FBSA particles onto the round-window membrane by microscopy. The FBSA particles, with good biocompatibility, drug-loading capacity, adhesive capability, and biodegradability, may have potential applications in the field of local drug delivery for inner-ear disease treatment.

  17. Tail-extension following the termination codon is critical for release of the nascent chain from membrane-bound ribosomes in a reticulocyte lysate cell-free system.

    Science.gov (United States)

    Takahara, Michiyo; Sakaue, Haruka; Onishi, Yukiko; Yamagishi, Marifu; Kida, Yuichiro; Sakaguchi, Masao

    2013-01-11

    Nascent chain release from membrane-bound ribosomes by the termination codon was investigated using a cell-free translation system from rabbit supplemented with rough microsomal membrane vesicles. Chain release was extremely slow when mRNA ended with only the termination codon. Tail extension after the termination codon enhanced the release of the nascent chain. Release reached plateau levels with tail extension of 10 bases. This requirement was observed with all termination codons: TAA, TGA and TAG. Rapid release was also achieved by puromycin even in the absence of the extension. Efficient translation termination cannot be achieved in the presence of only a termination codon on the mRNA. Tail extension might be required for correct positioning of the termination codon in the ribosome and/or efficient recognition by release factors. Copyright © 2012. Published by Elsevier Inc.

  18. Novel function of glutathione transferase in rat liver mitochondrial membrane: Role for cytochrome c release from mitochondria

    International Nuclear Information System (INIS)

    Lee, Kang Kwang; Shimoji, Manami; Hossain, Quazi Sohel; Sunakawa, Hajime; Aniya, Yoko

    2008-01-01

    Microsomal glutathione transferase (MGST1) is activated by oxidative stress. Although MGST1 is found in mitochondrial membranes (mtMGST1), there is no information about the oxidative activation of mtMGST1. In the present study, we aimed to determine whether mtMGST1 also undergoes activation and about its function. When rats were treated with galactosamine/lipopolysaccharide (GalN/LPS), mtMGST1 activity was significantly increased, and the increased activity was reduced by the disulfide reducing agent dithiothreitol. In mitochondria from GalN/LPS-treated rats, disulfide-linked mtMGST1 dimer and mixed protein glutathione disulfides (glutathionylation) were detected. In addition, cytochrome c release from mitochondria isolated from GalN/LPS-treated rats was observed, and the release was inhibited by anti-MGST1 antibodies. Incubation of mitochondria from control rats with diamide and diamide plus GSH in vitro resulted in dimer- and mixed disulfide bond-mediated activation of mtMGST1, respectively. The activation of mtMGST1 by diamide plus GSH caused cytochrome c release from the mitochondria, and the release was prevented by treatment with anti-MGST1 antibodies. In addition, diamide plus GSH treatment caused mitochondrial swelling accompanied by cytochrome c release, which was inhibited by cyclosporin A (CsA) and bongkrekic acid (BKA), inhibitors of the mitochondrial permeability transition (MPT) pore. Furthermore, mtMGST1 activity was also inhibited by CsA and BKA. These results indicate that mtMGST1 is activated through mixed disulfide bond formation that contributes to cytochrome c release from mitochondria through the MPT pore

  19. Intact transmembrane isoforms of the neural cell adhesion molecule are released from the plasma membrane

    DEFF Research Database (Denmark)

    Olsen, M; Krog, L; Edvardsen, K

    1993-01-01

    . By density-gradient centrifugation it was shown that shed transmembrane NCAM-B was present in fractions of high, as well as low, density, indicating that a fraction of the shed NCAM is associated with minor plasma membrane fragments. Finally, it was shown that isolated soluble NCAM inhibited cell binding...

  20. Oncolytic Group B Adenovirus Enadenotucirev Mediates Non-apoptotic Cell Death with Membrane Disruption and Release of Inflammatory Mediators

    Directory of Open Access Journals (Sweden)

    Arthur Dyer

    2017-03-01

    Full Text Available Enadenotucirev (EnAd is a chimeric group B adenovirus isolated by bioselection from a library of adenovirus serotypes. It replicates selectively in and kills a diverse range of carcinoma cells, shows effective anticancer activity in preclinical systems, and is currently undergoing phase I/II clinical trials. EnAd kills cells more quickly than type 5 adenovirus, and speed of cytotoxicity is dose dependent. The EnAd death pathway does not involve p53, is predominantly caspase independent, and appears to involve a rapid fall in cellular ATP. Infected cells show early loss of membrane integrity; increased exposure of calreticulin; extracellular release of ATP, HSP70, and HMGB1; and influx of calcium. The virus also causes an obvious single membrane blister reminiscent of ischemic cell death by oncosis. In human tumor biopsies maintained in ex vivo culture, EnAd mediated release of pro-inflammatory mediators such as TNF-α, IL-6, and HMGB1. In accordance with this, EnAd-infected tumor cells showed potent stimulation of dendritic cells and CD4+ T cells in a mixed tumor-leukocyte reaction in vitro. Whereas many viruses have evolved for efficient propagation with minimal inflammation, bioselection of EnAd for rapid killing has yielded a virus with a short life cycle that combines potent cytotoxicity with a proinflammatory mechanism of cell death.

  1. Cancer Patient T Cells Genetically Targeted to Prostate-Specific Membrane Antigen Specifically Lyse Prostate Cancer Cells and Release Cytokines in Response to Prostate-Specific Membrane Antigen

    Directory of Open Access Journals (Sweden)

    Michael C. Gong

    1999-06-01

    Full Text Available The expression of immunoglobulin-based artificial receptors in normal T lymphocytes provides a means to target lymphocytes to cell surface antigens independently of major histocompatibility complex restriction. Such artificial receptors have been previously shown to confer antigen-specific tumoricidal properties in murine T cells. We constructed a novel ζ chain fusion receptor specific for prostate-specific membrane antigen (PSMA termed Pz-1. PSMA is a cell-surface glycoprotein expressed on prostate cancer cells and the neovascular endothelium of multiple carcinomas. We show that primary T cells harvested from five of five patients with different stages of prostate cancer and transduced with the Pz-1 receptor readily lyse prostate cancer cells. Having established a culture system using fibroblasts that express PSMA, we next show that T cells expressing the Pz-1 receptor release cytokines in response to cell-bound PSMA. Furthermore, we show that the cytokine release is greatly augmented by B7.1-mediated costimulation. Thus, our findings support the feasibility of adoptive cell therapy by using genetically engineered T cells in prostate cancer patients and suggest that both CD4+ and CD8+ T lymphocyte functions can be synergistically targeted against tumor cells.

  2. Aminoacylation of the N-terminal cysteine is essential for Lol-dependent release of lipoproteins from membranes but does not depend on lipoprotein sorting signals.

    Science.gov (United States)

    Fukuda, Ayumu; Matsuyama, Shin-Ichi; Hara, Takashi; Nakayama, Jiro; Nagasawa, Hiromichi; Tokuda, Hajime

    2002-11-08

    Lipoproteins are present in a wide variety of bacteria and are anchored to membranes through lipids attached to the N-terminal cysteine. The Lol system of Escherichia coli mediates the membrane-specific localization of lipoproteins. Aspartate at position 2 functions as a Lol avoidance signal and causes the retention of lipoproteins in the inner membrane, whereas lipoproteins having residues other than aspartate at position 2 are released from the inner membrane and localized to the outer membrane by the Lol system. Phospholipid:apolipoprotein transacylase, Lnt, catalyzes the last step of lipoprotein modification, converting apolipoprotein into mature lipoprotein. To reveal the importance of this aminoacylation for the Lol-dependent membrane localization, apolipoproteins were prepared by inhibiting lipoprotein maturation. Lnt was also purified and used to convert apolipoprotein into mature lipoprotein in vitro. The release of these lipoproteins was examined in proteoliposomes. We show here that the aminoacylation is essential for the Lol-dependent release of lipoproteins from membranes. Furthermore, lipoproteins with aspartate at position 2 were found to be aminoacylated both in vivo and in vitro, indicating that the lipoprotein-sorting signal does not affect lipid modification.

  3. The Human Pathogen Streptococcus pyogenes Releases Lipoproteins as Lipoprotein-rich Membrane Vesicles.

    Science.gov (United States)

    Biagini, Massimiliano; Garibaldi, Manuela; Aprea, Susanna; Pezzicoli, Alfredo; Doro, Francesco; Becherelli, Marco; Taddei, Anna Rita; Tani, Chiara; Tavarini, Simona; Mora, Marirosa; Teti, Giuseppe; D'Oro, Ugo; Nuti, Sandra; Soriani, Marco; Margarit, Immaculada; Rappuoli, Rino; Grandi, Guido; Norais, Nathalie

    2015-08-01

    Bacterial lipoproteins are attractive vaccine candidates because they represent a major class of cell surface-exposed proteins in many bacteria and are considered as potential pathogen-associated molecular patterns sensed by Toll-like receptors with built-in adjuvanticity. Although Gram-negative lipoproteins have been extensively characterized, little is known about Gram-positive lipoproteins. We isolated from Streptococcus pyogenes a large amount of lipoproteins organized in vesicles. These vesicles were obtained by weakening the bacterial cell wall with a sublethal concentration of penicillin. Lipid and proteomic analysis of the vesicles revealed that they were enriched in phosphatidylglycerol and almost exclusively composed of lipoproteins. In association with lipoproteins, a few hypothetical proteins, penicillin-binding proteins, and several members of the ExPortal, a membrane microdomain responsible for the maturation of secreted proteins, were identified. The typical lipidic moiety was apparently not necessary for lipoprotein insertion in the vesicle bilayer because they were also recovered from the isogenic diacylglyceryl transferase deletion mutant. The vesicles were not able to activate specific Toll-like receptor 2, indicating that lipoproteins organized in these vesicular structures do not act as pathogen-associated molecular patterns. In light of these findings, we propose to name these new structures Lipoprotein-rich Membrane Vesicles. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Photo-cured pH-responsive polyampholyte-coated membranes for controlled release of drugs with different molecular weights and charges

    International Nuclear Information System (INIS)

    Ng, Loo-Teck; Ng, Kheng-Seong

    2008-01-01

    Intelligent drug delivery membranes were synthesised by photocuring poly(acrylic acid) (PAA) or polyampholytes comprised of copolymers of acrylic acid (AA)/2-(diethylamino)ethyl methacrylate (DEAEMA) with varying monomeric compositions onto poly(2-hydroxyethyl methacrylate) (PHEMA) membranes, each with model drugs of different molecular weights and charges being incorporated. pH-responsive release behaviours of the model drugs which included methylene blue (cationic), metanil yellow (anionic) and caffeine (neutral) were studied. Only membranes with methylene blue and caffeine incorporated displayed clear pH-responsive releases though all coatings. This study demonstrates that drug diffusion through pH-responsive membranes depends to a large extent on the attractive interaction between the drug and the appropriate functional group/s in the coating

  5. Presynaptic membrane receptors in acetylcholine release modulation in the neuromuscular synapse.

    Science.gov (United States)

    Tomàs, Josep; Santafé, Manel M; Garcia, Neus; Lanuza, Maria A; Tomàs, Marta; Besalduch, Núria; Obis, Teresa; Priego, Mercedes; Hurtado, Erica

    2014-05-01

    Over the past few years, we have studied, in the mammalian neuromuscular junction (NMJ), the local involvement in transmitter release of the presynaptic muscarinic ACh autoreceptors (mAChRs), purinergic adenosine autoreceptors (P1Rs), and trophic factor receptors (TFRs; for neurotrophins and trophic cytokines) during development and in the adult. At any given moment, the way in which a synapse works is largely the logical outcome of the confluence of these (and other) metabotropic signalling pathways on intracellular kinases, which phosphorylate protein targets and materialize adaptive changes. We propose an integrated interpretation of the complementary function of these receptors in the adult NMJ. The activity of a given receptor group can modulate a given combination of spontaneous, evoked, and activity-dependent release characteristics. For instance, P1Rs can conserve resources by limiting spontaneous quantal leak of ACh (an A1 R action) and protect synapse function, because stimulation with adenosine reduces the magnitude of depression during repetitive activity. The overall outcome of the mAChRs seems to contribute to upkeep of spontaneous quantal output of ACh, save synapse function by decreasing the extent of evoked release (mainly an M2 action), and reduce depression. We have also identified several links among P1Rs, mAChRs, and TFRs. We found a close dependence between mAChR and some TFRs and observed that the muscarinic group has to operate correctly if the tropomyosin-related kinase B receptor (trkB) is also to operate correctly, and vice versa. Likewise, the functional integrity of mAChRs depends on P1Rs operating normally. Copyright © 2014 Wiley Periodicals, Inc.

  6. Ultra Structural Characterisation of Tetherin - a Protein Capable of Preventing Viral Release from the Plasma Membrane

    Directory of Open Access Journals (Sweden)

    Ravindra K. Gupta

    2010-04-01

    Full Text Available Tetherin is an antiviral restriction factor made by mammalian cells to protect them from viral infection. It prevents newly formed virus particles from leaving infected cells. Its antiviral mechanism appears to be remarkably uncomplicated. In 2 studies published in PLoS Pathogens electron microscopy is used to support the hypothesis that the tethers that link HIV-1 virions to tetherin expressing cells contain tetherin and are likely to contain tetherin alone. They also show that the HIV-1 encoded tetherin antagonist that is known to cause tetherin degradation, Vpu, serves to reduce the amount of tetherin in the particles thereby allowing their release.

  7. Presynaptic Membrane Receptors Modulate ACh Release, Axonal Competition and Synapse Elimination during Neuromuscular Junction Development.

    Science.gov (United States)

    Tomàs, Josep; Garcia, Neus; Lanuza, Maria A; Santafé, Manel M; Tomàs, Marta; Nadal, Laura; Hurtado, Erica; Simó, Anna; Cilleros, Víctor

    2017-01-01

    During the histogenesis of the nervous system a lush production of neurons, which establish an excessive number of synapses, is followed by a drop in both neurons and synaptic contacts as maturation proceeds. Hebbian competition between axons with different activities leads to the loss of roughly half of the neurons initially produced so connectivity is refined and specificity gained. The skeletal muscle fibers in the newborn neuromuscular junction (NMJ) are polyinnervated but by the end of the competition, 2 weeks later, the NMJ are innervated by only one axon. This peripheral synapse has long been used as a convenient model for synapse development. In the last few years, we have studied transmitter release and the local involvement of the presynaptic muscarinic acetylcholine autoreceptors (mAChR), adenosine autoreceptors (AR) and trophic factor receptors (TFR, for neurotrophins and trophic cytokines) during the development of NMJ and in the adult. This review article brings together previously published data and proposes a molecular background for developmental axonal competition and loss. At the end of the first week postnatal, these receptors modulate transmitter release in the various nerve terminals on polyinnervated NMJ and contribute to axonal competition and synapse elimination.

  8. Presynaptic Membrane Receptors Modulate ACh Release, Axonal Competition and Synapse Elimination during Neuromuscular Junction Development

    Directory of Open Access Journals (Sweden)

    Josep Tomàs

    2017-05-01

    Full Text Available During the histogenesis of the nervous system a lush production of neurons, which establish an excessive number of synapses, is followed by a drop in both neurons and synaptic contacts as maturation proceeds. Hebbian competition between axons with different activities leads to the loss of roughly half of the neurons initially produced so connectivity is refined and specificity gained. The skeletal muscle fibers in the newborn neuromuscular junction (NMJ are polyinnervated but by the end of the competition, 2 weeks later, the NMJ are innervated by only one axon. This peripheral synapse has long been used as a convenient model for synapse development. In the last few years, we have studied transmitter release and the local involvement of the presynaptic muscarinic acetylcholine autoreceptors (mAChR, adenosine autoreceptors (AR and trophic factor receptors (TFR, for neurotrophins and trophic cytokines during the development of NMJ and in the adult. This review article brings together previously published data and proposes a molecular background for developmental axonal competition and loss. At the end of the first week postnatal, these receptors modulate transmitter release in the various nerve terminals on polyinnervated NMJ and contribute to axonal competition and synapse elimination.

  9. Ultraviolet radiation-induced interleukin 6 release in HeLa cells is mediated via membrane events in a DNA damage-independent way.

    Science.gov (United States)

    Kulms, D; Pöppelmann, B; Schwarz, T

    2000-05-19

    Evidence exists that ultraviolet radiation (UV) affects molecular targets in the nucleus or at the cell membrane. UV-induced apoptosis was found to be mediated via DNA damage and activation of death receptors, suggesting that nuclear and membrane effects are not mutually exclusive. To determine whether participation of nuclear and membrane components is also essential for other UV responses, we studied the induction of interleukin-6 (IL-6) by UV. Exposing HeLa cells to UV at 4 degrees C, which inhibits activation of surface receptors, almost completely prevented IL-6 release. Enhanced repair of UV-mediated DNA damage by addition of the DNA repair enzyme photolyase did not affect UV-induced IL-6 production, suggesting that in this case membrane events predominant over nuclear effects. UV-induced IL-6 release is mediated via NFkappaB since the NFkappaB inhibitor MG132 or transfection of cells with a super-repressor form of the NFkappaB inhibitor IkappaB reduced IL-6 release. Transfection with a dominant negative mutant of the signaling protein TRAF-2 reduced IL-6 release upon exposure to UV, indicating that UV-induced IL-6 release is mediated by activation of the tumor necrosis factor receptor-1. These data demonstrate that UV can exert biological effects mainly by affecting cell surface receptors and that this is independent of its ability to induce nuclear DNA damage.

  10. Azadirachtin-induced apoptosis involves lysosomal membrane permeabilization and cathepsin L release in Spodoptera frugiperda Sf9 cells.

    Science.gov (United States)

    Wang, Zheng; Cheng, Xingan; Meng, Qianqian; Wang, Peidan; Shu, Benshui; Hu, Qiongbo; Hu, Meiying; Zhong, Guohua

    2015-07-01

    Azadirachtin as a kind of botanical insecticide has been widely used in pest control. We previously reported that azadirachtin could induce apoptosis of Spodoptera litura cultured cell line Sl-1, which involves in the up-regulation of P53 protein. However, the detailed mechanism of azadirachtin-induced apoptosis is not clearly understood in insect cultured cells. The aim of the present study was to address the involvement of lysosome and lysosomal protease in azadirachtin-induced apoptosis in Sf9 cells. The result confirmed that azadirachtin indeed inhibited proliferation and induced apoptosis. The lysosomes were divided into different types as time-dependent manner, which suggested that changes of lysosomes were necessarily physiological processes in azadirachtin-induced apoptosis in Sf9 cells. Interestingly, we noticed that azadirachtin could trigger lysosomal membrane permeabilization and cathepsin L releasing to cytosol. Z-FF-FMK (a cathepsin L inhibitor), but not CA-074me (a cathepsin B inhibitor), could effectively hinder the apoptosis induced by azadirachtin in Sf9 cells. Meanwhile, the activity of caspase-3 could also be inactivated by the inhibition of cathepsin L enzymatic activity induced by Z-FF-FMK. Taken together, our findings suggest that azadirachtin could induce apoptosis in Sf9 cells in a lysosomal pathway, and cathepsin L plays a pro-apoptosis role in this process through releasing to cytosol and activating caspase-3. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Voltage clamp methods for the study of membrane currents and SR Ca2+ release in adult skeletal muscle fibres

    Science.gov (United States)

    Hernández-Ochoa, Erick O.; Schneider, Martin F.

    2012-01-01

    Skeletal muscle excitation-contraction (E-C)1 coupling is a process composed of multiple sequential stages, by which an action potential triggers sarcoplasmic reticulum (SR)2 Ca2+ release and subsequent contractile activation. The various steps in the E-C coupling process in skeletal muscle can be studied using different techniques. The simultaneous recordings of sarcolemmal electrical signals and the accompanying elevation in myoplasmic Ca2+, due to depolarization-initiated SR Ca2+ release in skeletal muscle fibres, have been useful to obtain a better understanding of muscle function. In studying the origin and mechanism of voltage dependency of E-C coupling a variety of different techniques have been used to control the voltage in adult skeletal fibres. Pioneering work in muscles isolated from amphibians or crustaceans used microelectrodes or ‘high resistance gap’ techniques to manipulate the voltage in the muscle fibres. The development of the patch clamp technique and its variant, the whole-cell clamp configuration that facilitates the manipulation of the intracellular environment, allowed the use of the voltage clamp techniques in different cell types, including skeletal muscle fibres. The aim of this article is to present an historical perspective of the voltage clamp methods used to study skeletal muscle E-C coupling as well as to describe the current status of using the whole-cell patch clamp technique in studies in which the electrical and Ca2+ signalling properties of mouse skeletal muscle membranes are being investigated. PMID:22306655

  12. Fibrous guided tissue regeneration membrane loaded with anti-inflammatory agent prepared by coaxial electrospinning for the purpose of controlled release

    Energy Technology Data Exchange (ETDEWEB)

    He, Min; Xue, Jiajia [Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Geng, Huan; Gu, Hao [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Chen, Dafu [Laboratory of Bone Tissue Engineering of Beijing Research Institute of Traumatology and Orthopaedics, Beijing 100035 (China); Shi, Rui, E-mail: sharell@126.com [Laboratory of Bone Tissue Engineering of Beijing Research Institute of Traumatology and Orthopaedics, Beijing 100035 (China); Zhang, Liqun, E-mail: zhanglq@mail.buct.edu.cn [Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)

    2015-04-30

    Graphical abstract: The metronidazole released from PCL/gelatin core/sheath nanofiber membranes can effectively inhibit the colonization of anerobic bacteria. - Highlights: • Core/sheath PCL/gelatin nanofiber membrane loaded with metronidazole in a wide range of drug loading (5–35 wt.%) were successfully fabricated in good quality. • The encapsulation of gelatin can effectively alleviate the initial burst release of drugs. • The membrane can inhibit the growth of bacteria as the drug content reaches 10% (w/w), and the bacterial inhibition ability can effectively last at least 4 weeks. • The encapsulation of gelatin can overcome the disadvantage of PCL's hydrophobicity, which can effectively promote the adhesion and proliferation of cells. - Abstract: Here, with the aim of inhibiting inflammation during guided tissue regeneration membrane (GTRM) implant surgery, coaxial electrospinning was used to fabricate drug-loaded core/sheath nanofiber GTRMs capable of controlled drug release. Various amounts of the anti-inflammatory agent metronidazole (MNA) were encapsulated into the core/sheath nanofibers (where PCL was the core, gelatin the sheath, and the gelatin shell was crosslinked with genipin) in order to establish the minimal drug content necessary to achieve the appropriate anti-inflammatory effect. By using TEM and SEM, the core/sheath structure was confirmed. In vitro drug disolution results showed that the core/sheath nanofibers exhibited sustained release profiles that were superior to those nanofibers produced by blending electrospinning. Additionally, the membrane significantly inhibited the colonization of anaerobic bacteria. Furthermore, with gelatin as a shell, the core/shell nanofiber membranes showed improved hydrophilicity, which resulted in better cell adhesion and proliferation without cytotoxicity. Therefore, in this study, a simple and effective coaxial electrospinning approach was demonstrated for the fabrication of anti

  13. Exceptionally tight membrane-binding may explain the key role of the synaptotagmin-7 C 2 A domain in asynchronous neurotransmitter release

    Energy Technology Data Exchange (ETDEWEB)

    Voleti, Rashmi; Tomchick, Diana R.; Südhof, Thomas C.; Rizo, Josep

    2017-09-18

    Synaptotagmins (Syts) act as Ca2+ sensors in neurotransmitter release by virtue of Ca2+-binding to their two C2 domains, but their mechanisms of action remain unclear. Puzzlingly, Ca2+-binding to the C2B domain appears to dominate Syt1 function in synchronous release, whereas Ca2+-binding to the C2A domain mediates Syt7 function in asynchronous release. Here we show that crystal structures of the Syt7 C2A domain and C2AB region, and analyses of intrinsic Ca2+-binding to the Syt7 C2 domains using isothermal titration calorimetry, did not reveal major differences that could explain functional differentiation between Syt7 and Syt1. However, using liposome titrations under Ca2+ saturating conditions, we show that the Syt7 C2A domain has a very high membrane affinity and dominates phospholipid binding to Syt7 in the presence or absence of L-α-phosphatidylinositol 4,5-diphosphate (PIP2). For Syt1, the two Ca2+-saturated C2 domains have similar affinities for membranes lacking PIP2, but the C2B domain dominates binding to PIP2-containing membranes. Mutagenesis revealed that the dramatic differences in membrane affinity between the Syt1 and Syt7 C2A domains arise in part from apparently conservative residue substitutions, showing how striking biochemical and functional differences can result from the cumulative effects of subtle residue substitutions. Viewed together, our results suggest that membrane affinity may be a key determinant of the functions of Syt C2 domains in neurotransmitter release.

  14. Differential Permeabilization Effects of Ca2+ and Valinomycin on the Inner and Outer Mitochondrial Membranes as Revealed by Proteomics Analysis of Proteins Released from Mitochondria*S⃞

    Science.gov (United States)

    Yamada, Akiko; Yamamoto, Takenori; Yamazaki, Naoshi; Yamashita, Kikuji; Kataoka, Masatoshi; Nagata, Toshihiko; Terada, Hiroshi; Shinohara, Yasuo

    2009-01-01

    It is well established that cytochrome c is released from mitochondria when the permeability transition (PT) of this organelle is induced by Ca2+. Our previous study showed that valinomycin also caused the release of cytochrome c from mitochondria but without inducing this PT (Shinohara, Y., Almofti, M. R., Yamamoto, T., Ishida, T., Kita, F., Kanzaki, H., Ohnishi, M., Yamashita, K., Shimizu, S., and Terada, H. (2002) Permeability transition-independent release of mitochondrial cytochrome c induced by valinomycin. Eur. J. Biochem. 269, 5224–5230). These results indicate that cytochrome c may be released from mitochondria with or without the induction of PT. In the present study, we examined the protein species released from valinomycin- and Ca2+-treated mitochondria by LC-MS/MS analysis. As a result, the proteins located in the intermembrane space were found to be specifically released from valinomycin-treated mitochondria, whereas those in the intermembrane space and in the matrix were released from Ca2+-treated mitochondria. These results were confirmed by Western analysis. Furthermore to examine how the protein release occurred, we examined the correlation between the species of released proteins and those of the abundant proteins in mitochondria. Consequently most of the proteins released from mitochondria treated with either agent were highly expressed proteins in mitochondria, indicating that the release occurred not selectively but in a manner dependent on the concentration of the proteins. Based on these results, the permeabilization effects of Ca2+ and valinomycin on the inner and outer mitochondrial membranes are discussed. PMID:19218587

  15. Photo-triggered release from liposomes without membrane solubilization, based on binding to poly(vinyl alcohol) carrying a malachite green moiety.

    Science.gov (United States)

    Uda, Ryoko M; Kato, Yutaka; Takei, Michiko

    2016-10-01

    When working with liposomes analogous to cell membranes, it is important to develop substrates that can regulate interactions with the liposome surface in response to light. We achieved a photo-triggered release from liposomes by using a copolymer of poly(vinyl alcohol) carrying a malachite green moiety (PVAMG). Although PVAMG is a neutral polymer under dark conditions, it is photoionized upon exposure to UV light, resulting in the formation of a cationic site for binding to liposomes with a negatively charged surface. Under UV irradiation, PVAMG showed effective interaction with liposomes, releasing the encapsulated compound; however, this release was negligible under dark conditions. The poly(vinyl alcohol) moiety of PVAMG played an important role in the photo-triggered release. This release was caused by membrane destabilization without lipid solubilization. We also investigated different aspects of liposome/PVAMG interactions, including PVAMG-induced fusion between the liposomes and the change in the liposome morphologies. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Extracellular Matrix (ECM) Multilayer Membrane as a Sustained Releasing Growth Factor Delivery System for rhTGF-β3 in Articular Cartilage Repair

    Science.gov (United States)

    Park, Sang-Hyug; Kim, Moon Suk; Kim, Young Jick; Choi, Byung Hyune; Lee, Chun Tek; Park, So Ra; Min, Byoung-Hyun

    2016-01-01

    Recombinant human transforming growth factor beta-3 (rhTGF-β3) is a key regulator of chondrogenesis in stem cells and cartilage formation. We have developed a novel drug delivery system that continuously releases rhTGF-β3 using a multilayered extracellular matrix (ECM) membrane. We hypothesize that the sustained release of rhTGF-β3 could activate stem cells and result in enhanced repair of cartilage defects. The properties and efficacy of the ECM multilayer-based delivery system (EMLDS) are investigated using rhTGF-β3 as a candidate drug. The bioactivity of the released rhTGF-ß3 was evaluated through chondrogenic differentiation of mesenchymal stem cells (MSCs) using western blot and circular dichroism (CD) analyses in vitro. The cartilage reparability was evaluated through implanting EMLDS with endogenous and exogenous MSC in both in vivo and ex vivo models, respectively. In the results, the sustained release of rhTGF-ß3 was clearly observed over a prolonged period of time in vitro and the released rhTGF-β3 maintained its structural stability and biological activity. Successful cartilage repair was also demonstrated when rabbit MSCs were treated with rhTGF-β3-loaded EMLDS ((+) rhTGF-β3 EMLDS) in an in vivo model and when rabbit chondrocytes and MSCs were treated in ex vivo models. Therefore, the multilayer ECM membrane could be a useful drug delivery system for cartilage repair. PMID:27258120

  17. Extracellular Matrix (ECM Multilayer Membrane as a Sustained Releasing Growth Factor Delivery System for rhTGF-β3 in Articular Cartilage Repair.

    Directory of Open Access Journals (Sweden)

    Soon Sim Yang

    Full Text Available Recombinant human transforming growth factor beta-3 (rhTGF-β3 is a key regulator of chondrogenesis in stem cells and cartilage formation. We have developed a novel drug delivery system that continuously releases rhTGF-β3 using a multilayered extracellular matrix (ECM membrane. We hypothesize that the sustained release of rhTGF-β3 could activate stem cells and result in enhanced repair of cartilage defects. The properties and efficacy of the ECM multilayer-based delivery system (EMLDS are investigated using rhTGF-β3 as a candidate drug. The bioactivity of the released rhTGF-ß3 was evaluated through chondrogenic differentiation of mesenchymal stem cells (MSCs using western blot and circular dichroism (CD analyses in vitro. The cartilage reparability was evaluated through implanting EMLDS with endogenous and exogenous MSC in both in vivo and ex vivo models, respectively. In the results, the sustained release of rhTGF-ß3 was clearly observed over a prolonged period of time in vitro and the released rhTGF-β3 maintained its structural stability and biological activity. Successful cartilage repair was also demonstrated when rabbit MSCs were treated with rhTGF-β3-loaded EMLDS ((+ rhTGF-β3 EMLDS in an in vivo model and when rabbit chondrocytes and MSCs were treated in ex vivo models. Therefore, the multilayer ECM membrane could be a useful drug delivery system for cartilage repair.

  18. Cavin-1/PTRF alters prostate cancer cell-derived extracellular vesicle content and internalization to attenuate extracellular vesicle-mediated osteoclastogenesis and osteoblast proliferation

    Directory of Open Access Journals (Sweden)

    Kerry L. Inder

    2014-06-01

    Full Text Available Background: Tumour-derived extracellular vesicles (EVs play a role in tumour progression; however, the spectrum of molecular mechanisms regulating EV secretion and cargo selection remain to be fully elucidated. We have reported that cavin-1 expression in prostate cancer PC3 cells reduced the abundance of a subset of EV proteins, concomitant with reduced xenograft tumour growth and metastasis. Methods: We examined the functional outcomes and mechanisms of cavin-1 expression on PC3-derived EVs (PC3-EVs. Results: PC3-EVs were internalized by osteoclast precursor RAW264.7 cells and primary human osteoblasts (hOBs in vitro, stimulating osteoclastogenesis 37-fold and hOB proliferation 1.5-fold, respectively. Strikingly, EVs derived from cavin-1-expressing PC3 cells (cavin-1-PC3-EVs failed to induce multinucleate osteoblasts or hOB proliferation. Cavin-1 was not detected in EVs, indicating an indirect mechanism of action. EV morphology, size and quantity were also not affected by cavin-1 expression, suggesting that cavin-1 modulated EV cargo recruitment rather than release. While cavin-1-EVs had no osteoclastogenic function, they were internalized by RAW264.7 cells but at a reduced efficiency compared to control EVs. EV surface proteins are required for internalization of PC3-EVs by RAW264.7 cells, as proteinase K treatment abolished uptake of both control and cavin-1-PC3-EVs. Removal of sialic acid modifications by neuraminidase treatment increased the amount of control PC3-EVs internalized by RAW264.7 cells, without affecting cavin-1-PC3-EVs. This suggests that cavin-1 expression altered the glycosylation modifications on PC3-EV surface. Finally, cavin-1 expression did not affect EV in vivo tissue targeting as both control and cavin-1-PC3-EVs were predominantly retained in the lung and bone 24 hours after injection into mice. Discussion: Taken together, our results reveal a novel pathway for EV cargo sorting, and highlight the potential of utilizing

  19. Release of Glycoprotein (GP1 from the Tegumental Surface of Taenia solium by Phospholipase C from Clostridium perfringens Suggests a Novel Protein-Anchor to Membranes

    Directory of Open Access Journals (Sweden)

    Abraham Landa

    2010-01-01

    Full Text Available In order to explore how molecules are linked to the membrane surface in larval Taenia solium, whole cysticerci were incubated in the presence of phospholipase C from Clostridium perfringens (PLC. Released material was collected and analyzed in polyacrylamide gels with sodium dodecyl sulfate. Two major bands with apparent molecular weights of 180 and 43 kDa were observed. Western blot of released material and localization assays in cysticerci tissue sections using antibodies against five known surface glycoproteins of T. solium cysticerci indicated that only one, previously called GP1, was released. Similar localization studies using the lectins wheat-germ-agglutinin and Concanavalin A showed that N-acetyl-D-glucosamine, N-acetylneuraminic, sialic acid, αmethyl-D-mannoside, D-manose/glucose, and N-acetyl-D-glucosamine residues are abundantly present on the surface. On the other hand, we find that treatment with PLC releases molecules from the surface; they do not reveal Cross Reacting Determinant (CRD, suggesting a novel anchor to the membrane for the glycoprotein GP1.

  20. Effect of Na2SO3 concentration to drug loading and drug release of ascorbic acid in chitosan edible film as drug delivery system membrane

    Directory of Open Access Journals (Sweden)

    Kistriyani Lilis

    2018-01-01

    Full Text Available Chitosan is a type of carbohydrate compounds produced from waste marine products, in particular the class of shrimp, crabs and clams. Chitosan is often process into edible films and utilized for food packaging also has potential as a membrane for drug delivery system. Drug loading and drug release can be controlled by improve the characteristics of the membrane by adding crosslinker. The purpose of this research is to study the effect of addition of crosslinker to the rate of loading and release of ascorbic acid in the chitosan edible film. Na2SO3 was used as crosslinker. Two grams of chitosan was dissolved into 100 ml of distilled water. Acetic acid and plasticizer were added in the solution then heated at 50°C. Na2SO3 solution with mass various of Na2SO3 dissolved, 01026 0.3; and 0.5 grams were added about 30 mL to make edible film. The analysis include of drug loading, drug release and tensile strength. The result showed that the loading of edible film with crosslinker 0.15 g; 0.3 g; and 0.5 g respectively were 60.98 ppm; 52.53 ppm; and 40.88 ppm, meanwhile for the release with crosslinker 0.15 g; 0.3 g; and 0.5 g respectively were 3.78 ppm; 5.72 ppm; and 5.97 ppm.

  1. Controlling the Release of Indomethacin from Glass Solutions Layered with a Rate Controlling Membrane Using Fluid-Bed Processing. Part 1: Surface and Cross-Sectional Chemical Analysis.

    Science.gov (United States)

    Dereymaker, Aswin; Scurr, David J; Steer, Elisabeth D; Roberts, Clive J; Van den Mooter, Guy

    2017-04-03

    Fluid bed coating has been shown to be a suitable manufacturing technique to formulate poorly soluble drugs in glass solutions. Layering inert carriers with a drug-polymer mixture enables these beads to be immediately filled into capsules, thus avoiding additional, potentially destabilizing, downstream processing. In this study, fluid bed coating is proposed for the production of controlled release dosage forms of glass solutions by applying a second, rate controlling membrane on top of the glass solution. Adding a second coating layer adds to the physical and chemical complexity of the drug delivery system, so a thorough understanding of the physical structure and phase behavior of the different coating layers is needed. This study aimed to investigate the surface and cross-sectional characteristics (employing scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS)) of an indomethacin-polyvinylpyrrolidone (PVP) glass solution, top-coated with a release rate controlling membrane consisting of either ethyl cellulose or Eudragit RL. The implications of the addition of a pore former (PVP) and the coating medium (ethanol or water) were also considered. In addition, polymer miscibility and the phase analysis of the underlying glass solution were investigated. Significant differences in surface and cross-sectional topography of the different rate controlling membranes or the way they are applied (solution vs dispersion) were observed. These observations can be linked to the polymer miscibility differences. The presence of PVP was observed in all rate controlling membranes, even if it is not part of the coating solution. This could be attributed to residual powder presence in the coating chamber. The distribution of PVP among the sample surfaces depends on the concentration and the rate controlling polymer used. Differences can again be linked to polymer miscibility. Finally, it was shown that the underlying glass solution layer

  2. Expression of the Gastrin-Releasing Peptide Receptor, the Prostate Stem Cell Antigen and the Prostate-Specific Membrane Antigen in Lymph Node and Bone Metastases of Prostate Cancer

    NARCIS (Netherlands)

    Ananias, Hildo J. K.; van den Heuvel, Marius C.; Helfrich, Wijnand; de Jong, Igle J.

    2009-01-01

    OBJECTIVE. Cell membrane antigens like the gastrin-releasing peptide receptor (GRPR), the prostate stem cell antigen (PSCA), and the prostate-specific membrane antigen (PSMA), expressed in prostate cancer, are attractive targets for new therapeutic and diagnostic applications. Therefore, we

  3. Body weight loss, reduced urge for palatable food and increased release of GLP-1 through daily supplementation with green-plant membranes for three months in overweight women.

    Science.gov (United States)

    Montelius, Caroline; Erlandsson, Daniel; Vitija, Egzona; Stenblom, Eva-Lena; Egecioglu, Emil; Erlanson-Albertsson, Charlotte

    2014-10-01

    The frequency of obesity has risen dramatically in recent years but only few effective and safe drugs are available. We investigated if green-plant membranes, previously shown to reduce subjective hunger and promote satiety signals, could affect body weight when given long-term. 38 women (40-65 years of age, body mass index 25-33 kg/m(2)) were randomized to dietary supplementation with either green-plant membranes (5 g) or placebo, consumed once daily before breakfast for 12 weeks. All individuals were instructed to follow a three-meal paradigm without any snacking between the meals and to increase their physical activity. Body weight change was analysed every third week as was blood glucose and various lipid parameters. On days 1 and 90, following intake of a standardized breakfast, glucose, insulin and glucagon-like peptide 1 (GLP-1) in plasma were measured, as well as subjective ratings of hunger, satiety and urge for different palatable foods, using visual analogue scales. Subjects receiving green-plant membranes lost significantly more body weight than did those on placebo (p weight loss with green-plant extract was 5.0 ± 2.3 kg compared to 3.5 ± 2.3 kg in the control group. Consumption of green-plant membranes also reduced total and LDL-cholesterol (p meal tests performed on day 1 and day 90 demonstrated an increased postprandial release of GLP-1 and decreased urge for sweet and chocolate on both occasions in individuals supplemented with green-plant membranes compared to control. Waist circumference, body fat and leptin decreased in both groups over the course of the study, however there were no differences between the groups. In conclusion, addition of green-plant membranes as a dietary supplement once daily induces weight loss, improves obesity-related risk-factors, and reduces the urge for palatable food. The mechanism may reside in the observed increased release of GLP-1. Copyright © 2014 The Authors. Published by Elsevier Ltd

  4. Membrane depolarization increases ryanodine sensitivity to Ca2+ release to the cytosol in L6 skeletal muscle cells: Implications for excitation-contraction coupling.

    Science.gov (United States)

    Pitake, Saumitra; Ochs, Raymond S

    2016-04-01

    The dihydropyridine receptor in the plasma membrane and the ryanodine receptor in the sarcoplasmic reticulum are known to physically interact in the process of excitation-contraction coupling. However, the mechanism for subsequent Ca(2+) release through the ryanodine receptor is unknown. Our lab has previously presented evidence that the dihydropyridine receptor and ryanodine receptor combine as a channel for the entry of Ca(2+) under resting conditions, known as store operated calcium entry. Here, we provide evidence that depolarization during excitation-contraction coupling causes the dihydropyridine receptor to disengage from the ryanodine receptor. The newly freed ryanodine receptor can then transport Ca(2+) from the sarcoplasmic reticulum to the cytosol. Experimentally, this should more greatly expose the ryanodine receptor to exogenous ryanodine. To examine this hypothesis, we titrated L6 skeletal muscle cells with ryanodine in resting and excited (depolarized) states. When L6 muscle cells were depolarized with high potassium or exposed to the dihydropyridine receptor agonist BAYK-8644, known to induce dihydropyridine receptor movement within the membrane, ryanodine sensitivity was enhanced. However, ryanodine sensitivity was unaffected when Ca(2+) was elevated without depolarization by the ryanodine receptor agonist chloromethylcresol, or by increasing Ca(2+) concentration in the media. Ca(2+) entry currents (from the extracellular space) during excitation were strongly inhibited by ryanodine, but Ca(2+) entry currents in the resting state were not. We conclude that excitation releases the ryanodine receptor from occlusion by the dihydropyridine receptor, enabling Ca(2+) release from the ryanodine receptor to the cytosol. © 2015 by the Society for Experimental Biology and Medicine.

  5. Determination of particle-release conditions in microfiltration: A simple single-particle model tested on a model membrane

    NARCIS (Netherlands)

    Kuiper, S.; van Rijn, C.J.M.; Nijdam, W.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

    2000-01-01

    A simple single-particle model was developed for cross-flow microfiltration with microsieves. The model describes the cross-flow conditions required to release a trapped spherical particle from a circular pore. All equations are derived in a fully analytical way without any fitting parameters. For

  6. Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells

    Directory of Open Access Journals (Sweden)

    Watson Cheryl S

    2010-10-01

    Full Text Available Abstract Background Xenoestrogens such as alkylphenols and the structurally related plastic byproduct bisphenol A have recently been shown to act potently via nongenomic signaling pathways and the membrane version of estrogen receptor-α. Though the responses to these compounds are typically measured individually, they usually contaminate organisms that already have endogenous estrogens present. Therefore, we used quantitative medium-throughput screening assays to measure the effects of physiologic estrogens in combination with these xenoestrogens. Methods We studied the effects of low concentrations of endogenous estrogens (estradiol, estriol, and estrone at 10 pM (representing pre-development levels, and 1 nM (representing higher cycle-dependent and pregnancy levels in combinations with the same levels of xenoestrogens in GH3/B6/F10 pituitary cells. These levels of xenoestrogens represent extremely low contamination levels. We monitored calcium entry into cells using Fura-2 fluorescence imaging of single cells. Prolactin release was measured by radio-immunoassay. Extracellular-regulated kinase (1 and 2 phospho-activations and the levels of three estrogen receptors in the cell membrane (ERα, ERβ, and GPER were measured using a quantitative plate immunoassay of fixed cells either permeabilized or nonpermeabilized (respectively. Results All xenoestrogens caused responses at these concentrations, and had disruptive effects on the actions of physiologic estrogens. Xenoestrogens reduced the % of cells that responded to estradiol via calcium channel opening. They also inhibited the activation (phosphorylation of extracellular-regulated kinases at some concentrations. They either inhibited or enhanced rapid prolactin release, depending upon concentration. These latter two dose-responses were nonmonotonic, a characteristic of nongenomic estrogenic responses. Conclusions Responses mediated by endogenous estrogens representing different life stages are

  7. EMMPRIN/CD147-encriched membrane vesicles released from malignant human testicular germ cells increase MMP production through tumor-stroma interaction.

    Science.gov (United States)

    Milia-Argeiti, Eleni; Mourah, Samia; Vallée, Benoit; Huet, Eric; Karamanos, Nikos K; Theocharis, Achilleas D; Menashi, Suzanne

    2014-08-01

    Elevated levels of EMMPRIN/CD147 in cancer tissues have been correlated with tumor progression but the regulation of its expression is not yet understood. Here, the regulation of EMMPRIN expression was investigated in testicular germ cell tumor (TGCTs) cell lines. EMMPRIN expression in seminoma JKT-1 and embryonal carcinoma NT2/D1 cell lines was determined by Western blot, immunofluorescence and qRT-PCR. Membrane vesicles (MVs) secreted from these cells, treated or not with EMMPRIN siRNA, were isolated by differential centrifugations of their conditioned medium. MMP-2 was analyzed by zymography and qRT-PCR. The more aggressive embryonic carcinoma NT2/D1 cells expressed more EMMPRIN mRNA than the seminoma JKT-1 cells, but surprisingly contained less EMMPRIN protein, as determined by immunoblotting and immunostaining. The protein/mRNA discrepancy was not due to accelerated protein degradation in NT2/D1 cells, but by the secretion of EMMPRIN within MVs, as the vesicles released from NT2/D1 contained considerably more EMMPRIN than those released from JKT-1. EMMPRIN-containing MVs obtained from NT2/D1, but not from EMMPRIN-siRNA treated NT2/D1, increased MMP-2 production in fibroblasts to a greater extent than those from JKT-1 cells. The data presented show that the more aggressive embryonic carcinoma cells synthesize more EMMPRIN than seminoma cells, but which they preferentially target to secreted MVs, unlike seminoma cells which retain EMMPRIN within the cell membrane. This cellular event points to a mechanism by which EMMPRIN expressed by malignant testicular cells can exert its MMP inducing effect on distant cells within the tumor microenvironment to promote tumor invasion. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Exosomes released by EBV-infected nasopharyngeal carcinoma cells convey the viral Latent Membrane Protein 1 and the immunomodulatory protein galectin 9

    International Nuclear Information System (INIS)

    Keryer-Bibens, Cécile; Pioche-Durieu, Catherine; Villemant, Cécile; Souquère, Sylvie; Nishi, Nozomu; Hirashima, Mitsuomi; Middeldorp, Jaap; Busson, Pierre

    2006-01-01

    Nasopharyngeal carcinomas (NPC) are consistently associated with the Epstein-Barr virus (EBV). Their malignant epithelial cells contain the viral genome and express several antigenic viral proteins. However, the mechanisms of immune escape in NPCs are still poorly understood. EBV-transformed B-cells have been reported to release exosomes carrying the EBV-encoded latent membrane protein 1 (LMP1) which has T-cell inhibitory activity. Although this report suggested that NPC cells could also produce exosomes carrying immunosuppressive proteins, this hypothesis has remained so far untested. Malignant epithelial cells derived from NPC xenografts – LMP1-positive (C15) or negative (C17) – were used to prepare conditioned culture medium. Various microparticles and vesicles released in the culture medium were collected and fractionated by differential centrifugation. Exosomes collected in the last centrifugation step were further purified by immunomagnetic capture on beads carrying antibody directed to HLA class II molecules. Purified exosomes were visualized by electron microscopy and analysed by western blotting. The T-cell inhibitory activities of recombinant LMP1 and galectin 9 were assessed on peripheral blood mononuclear cells activated by CD3/CD28 cross-linking. HLA-class II-positive exosomes purified from C15 and C17 cell supernatants were containing either LMP1 and galectin 9 (C15) or galectin 9 only (C17). Recombinant LMP1 induced a strong inhibition of T-cell proliferation (IC50 = 0.17 nM). In contrast recombinant galectin 9 had a weaker inhibitory effect (IC50 = 46 nM) with no synergy with LMP1. This study provides the proof of concept that NPC cells can release HLA class-II positive exosomes containing galectin 9 and/or LMP1. It confirms that the LMP1 molecule has intrinsic T-cell inhibitory activity. These findings will encourage investigations of tumor exosomes in the blood of NPC patients and assessment of their effects on various types of target cells

  9. Participation of the endoplasmic reticulum protein chaperone thio-oxidoreductase in gonadotropin-releasing hormone receptor expression at the plasma membrane

    Directory of Open Access Journals (Sweden)

    W. Lucca-Junior

    2009-02-01

    Full Text Available Chaperone members of the protein disulfide isomerase family can catalyze the thiol-disulfide exchange reaction with pairs of cysteines. There are 14 protein disulfide isomerase family members, but the ability to catalyze a thiol disulfide exchange reaction has not been demonstrated for all of them. Human endoplasmic reticulum protein chaperone thio-oxidoreductase (ERp18 shows partial oxidative activity as a protein disulfide isomerase. The aim of the present study was to evaluate the participation of ERp18 in gonadotropin-releasing hormone receptor (GnRHR expression at the plasma membrane. Cos-7 cells were cultured, plated, and transfected with 25 ng (unless indicated wild-type human GnRHR (hGnRHR or mutant GnRHR (Cys14Ala and Cys200Ala and pcDNA3.1 without insert (empty vector or ERp18 cDNA (75 ng/well, pre-loaded for 18 h with 1 µCi myo-[2-3H(N]-inositol in 0.25 mL DMEM and treated for 2 h with buserelin. We observed a decrease in maximal inositol phosphate (IP production in response to buserelin in the cells co-transfected with hGnRHR, and a decrease from 20 to 75 ng of ERp18 compared with cells co-transfected with hGnRHR and empty vector. The decrease in maximal IP was proportional to the amount of ERp18 DNA over the range examined. Mutants (Cys14Ala and Cys200Ala that could not form the Cys14-Cys200 bridge essential for plasma membrane routing of the hGnRHR did not modify maximal IP production when they were co-transfected with ERp18. These results suggest that ERp18 has a reduction role on disulfide bonds in wild-type hGnRHR folding.

  10. Plasma membrane ordering agent pluronic F-68 (PF-68) reduces neurotransmitter uptake and release and produces learning and memory deficits in rats

    Science.gov (United States)

    Clarke, M. S.; Prendergast, M. A.; Terry, A. V. Jr

    1999-01-01

    A substantial body of evidence indicates that aged-related changes in the fluidity and lipid composition of the plasma membrane contribute to cellular dysfunction in humans and other mammalian species. In the CNS, reductions in neuronal plasma membrane order (PMO) (i.e., increased plasma membrane fluidity) have been attributed to age as well as the presence of the beta-amyloid peptide-25-35, known to play an important role in the neuropathology of Alzheimer's disease (AD). These PMO increases may influence neurotransmitter synthesis, receptor binding, and second messenger systems as well as signal transduction pathways. The effects of neuronal PMO on learning and memory processes have not been adequately investigated, however. Based on the hypothesis that an increase in PMO may alter a number of aspects of synaptic transmission, we investigated several neurochemical and behavioral effects of the membrane ordering agent, PF-68. In cell culture, PF-68 (nmoles/mg SDS extractable protein) reduced [3H]norepinephrine (NE) uptake into differentiated PC-12 cells as well as reduced nicotine stimulated [3H]NE release. The compound (800-2400 microg/kg, i.p., resulting in nmoles/mg SDS extractable protein in the brain) decreased step-through latencies and increased the frequencies of crossing into the unsafe side of the chamber in inhibitory avoidance training. In the Morris water maze, PF-68 increased the latencies and swim distances required to locate a hidden platform and reduced the time spent and distance swam in the previous target quadrant during transfer (probe) trials. PF-68 did not impair performance of a well-learned working memory task, the rat delayed stimulus discrimination task (DSDT), however. Studies with 14C-labeled PF-68 indicated that significant (pmoles/mg wet tissue) levels of the compound entered the brain from peripheral (i.p.) injection. No PF-68 related changes were observed in swim speeds or in visual acuity tests in water maze experiments, rotorod

  11. Helicobacter pylori-elicited induction in gastric mucosal matrix metalloproteinase-9 (MMP-9) release involves ERK-dependent cPLA2 activation and its recruitment to the membrane-localized Rac1/p38 complex.

    Science.gov (United States)

    Slomiany, B L; Slomiany, A

    2016-06-01

    Matrix metalloproteinases (MMPs) are a family of endopeptidases implicated in a wide rage of degenerative and inflammatory diseases, including Helicobacter pylori-associated gastritis, and gastric and duodenal ulcer. As gastric mucosal inflammatory responses to H. pylori are characterized by the rise in MMP-9 production, as well as the induction in mitogen-activated protein kinase (MAPK) and Rac1 activation, we investigated the role of Rac1/MAPK in the processes associated with the release of MMP-9. We show that H. pylori LPS-elicited induction in gastric mucosal MMP-9 release is associated with MAPK, ERK and p38 activation, and occurs with the involvement of Rac1 and cytosolic phospholipase A2 (cPLA2). Further, we demonstrate that the LPS-induced MMP-9 release requires ERK-mediated phosphorylation of cPLA2 on Ser(505) that is essential for its membrane localization with Rac1, and that this process necessitates p38 participation. Moreover, we reveal that the activation and membrane translocation of p38 to the Rac1-GTP complex plays a pivotal role in cPLA2-dependent enhancement in MMP-9 release. Hence, our findings provide a strong evidence for the role of ERK/cPLA2 and Rac1/p38/cPLA2 cascade in H. pylori LPS-induced up-regulation in gastric mucosal MMP-9 release.

  12. Controlled release of linalool using nanofibrous membranes of poly(lactic acid) obtained by electrospinning and solution blow spinning: A comparative study

    Science.gov (United States)

    The controlled-release of natural plant oils such as linalool is of interest in therapeutics, cosmetics, and antimicrobial and larvicidal products. The present study reports the release characteristics of linalool encapsulated at three concentrations (10, 15 and 20 wt.%) in poly(lactic acid) nanofib...

  13. Activation of moesin, a protein that links actin cytoskeleton to the plasma membrane, occurs by phosphatidylinositol 4,5-bisphosphate (PIP2) binding sequentially to two sites and releasing an autoinhibitory linker.

    Science.gov (United States)

    Ben-Aissa, Khadija; Patino-Lopez, Genaro; Belkina, Natalya V; Maniti, Ofelia; Rosales, Tilman; Hao, Jian-Jiang; Kruhlak, Michael J; Knutson, Jay R; Picart, Catherine; Shaw, Stephen

    2012-05-11

    Many cellular processes depend on ERM (ezrin, moesin, and radixin) proteins mediating regulated linkage between plasma membrane and actin cytoskeleton. Although conformational activation of the ERM protein is mediated by the membrane PIP2, the known properties of the two described PIP2-binding sites do not explain activation. To elucidate the structural basis of possible mechanisms, we generated informative moesin mutations and tested three attributes: membrane localization of the expressed moesin, moesin binding to PIP2, and PIP2-induced release of moesin autoinhibition. The results demonstrate for the first time that the POCKET containing inositol 1,4,5-trisphosphate on crystal structure (the "POCKET" Lys-63, Lys-278 residues) mediates all three functions. Furthermore the second described PIP2-binding site (the "PATCH," Lys-253/Lys-254, Lys-262/Lys-263) is also essential for all three functions. In native autoinhibited ERM proteins, the POCKET is a cavity masked by an acidic linker, which we designate the "FLAP." Analysis of three mutant moesin constructs predicted to influence FLAP function demonstrated that the FLAP is a functional autoinhibitory region. Moreover, analysis of the cooperativity and stoichiometry demonstrate that the PATCH and POCKET do not bind PIP2 simultaneously. Based on our data and supporting published data, we propose a model of progressive activation of autoinhibited moesin by a single PIP2 molecule in the membrane. Initial transient binding of PIP2 to the PATCH initiates release of the FLAP, which enables transition of the same PIP2 molecule into the newly exposed POCKET where it binds stably and completes the conformational activation.

  14. Deep sequencing of RNA from immune cell-derived vesicles uncovers the selective incorporation of small non-coding RNA biotypes with potential regulatory functions.

    NARCIS (Netherlands)

    Nolte-'t Hoen, E.N.M.; Buermans, H.P.; Waasdorp, M.; Stoorvogel, W.; Wauben, M.H.M.; `t Hoen, P.A.C.

    2012-01-01

    Cells release RNA-carrying vesicles and membrane-free RNA/protein complexes into the extracellular milieu. Horizontal vesicle-mediated transfer of such shuttle RNA between cells allows dissemination of genetically encoded messages, which may modify the function of target cells. Other studies used

  15. Streptococcus mutans Extracellular DNA Is Upregulated during Growth in Biofilms, Actively Released via Membrane Vesicles, and Influenced by Components of the Protein Secretion Machinery

    Science.gov (United States)

    Liao, Sumei; Klein, Marlise I.; Heim, Kyle P.; Fan, Yuwei; Bitoun, Jacob P.; Ahn, San-Joon; Burne, Robert A.; Koo, Hyun; Brady, L. Jeannine

    2014-01-01

    Streptococcus mutans, a major etiological agent of human dental caries, lives primarily on the tooth surface in biofilms. Limited information is available concerning the extracellular DNA (eDNA) as a scaffolding matrix in S. mutans biofilms. This study demonstrates that S. mutans produces eDNA by multiple avenues, including lysis-independent membrane vesicles. Unlike eDNAs from cell lysis that were abundant and mainly concentrated around broken cells or cell debris with floating open ends, eDNAs produced via the lysis-independent pathway appeared scattered but in a structured network under scanning electron microscopy. Compared to eDNA production of planktonic cultures, eDNA production in 5- and 24-h biofilms was increased by >3- and >1.6-fold, respectively. The addition of DNase I to growth medium significantly reduced biofilm formation. In an in vitro adherence assay, added chromosomal DNA alone had a limited effect on S. mutans adherence to saliva-coated hydroxylapatite beads, but in conjunction with glucans synthesized using purified glucosyltransferase B, the adherence was significantly enhanced. Deletion of sortase A, the transpeptidase that covalently couples multiple surface-associated proteins to the cell wall peptidoglycan, significantly reduced eDNA in both planktonic and biofilm cultures. Sortase A deficiency did not have a significant effect on membrane vesicle production; however, the protein profile of the mutant membrane vesicles was significantly altered, including reduction of adhesin P1 and glucan-binding proteins B and C. Relative to the wild type, deficiency of protein secretion and membrane protein insertion machinery components, including Ffh, YidC1, and YidC2, also caused significant reductions in eDNA. PMID:24748612

  16. The Effect in Vitro of Ionizing Irradiation and Small Rises in Temperature on the Uptake and Release of Labelled Lipids by the Human Erythrocyte Membrane

    DEFF Research Database (Denmark)

    Hansen, Heinz Johs. Max; Karle, H.; Stender, S.

    1978-01-01

    1. The effect of X-irradiation (50 000 rad) and an increase in temperature from 37 to 42° C on the synthesis, uptake and release of labelled lipids by erythrocytes was studied in plasma incubations in vitro. 2. Both irradiation and a rise in temperature resulted in an enhanced synthesis of [32P]phosphatidic...

  17. The 78 kDa glucose-regulated protein (GRP78/BIP) is expressed on the cell membrane, is released into cell culture medium and is also present in human peripheral circulation.

    Science.gov (United States)

    Delpino, Andrea; Castelli, Mauro

    2002-01-01

    In human rabdomiosarcoma cells (TE671/RD) chronic exposure to 500 nM thapsigargin (a powerful inhibitor of the endoplasmic reticulum Ca2+-ATPases) resulted in the induction of the stress protein GRP78/BIP. Making use of the surface biotinylation method, followed by the isolation of the GRP78 using ATP-agarose affinity chromatography, it was found that a fraction of the thapsigargin-induced GRP78 is expressed on the cell surface. The presence of GRP78 on the membrane of thapsigargin-treated cells was confirmed by fractionation of cell lysates into a soluble and a membrane fraction, followed by Western blot analysis with an anti-GRP78 antibody. It was also found that conspicuous amounts of GRP78 are present in the culture medium collected from thapsigargin-treated cultures. This extracellular GRP78 originates mostly by an active release from intact cells and does not result solely from the leakage of proteins from dead cells. Moreover, small amounts of circulating, free GRP78 and naturally-occurring anti-GRP78 autoantibodies were detected in the peripheral circulation of healthy human individuals.

  18. Spontaneous release of epiretinal membrane in a young weight-lifting athlete by presumed central rupture and centrifugal pull

    Directory of Open Access Journals (Sweden)

    Mansour AM

    2014-11-01

    Full Text Available Ahmad M Mansour,1,2 Hana A Mansour,3 J Fernando Arevalo4,5 1Department of Ophthalmology, Rafic Hariri University Hospital, Beirut, Lebanon; 2Department of Ophthalmology, American University of Beirut, Beirut, Lebanon; 3Department of Biology, American University of Beirut, Beirut, Lebanon; 4Retina Department, The King Khaled Eye Specialist Hospital, Riyadh, Kingdom of Saudi Arabia; 5Retina Department, Wilmer Eye Institute, The Johns Hopkins University, Baltimore, MD, USA Abstract: This patient presented for surgery at the age of 32 years, 14 months after his initial complaint of metamorphopsia and visual loss in the right eye. Past tests demonstrated a whitish epiretinal membrane (ERM with translucent stress lines over a thickened macula. Visual acuity was found on last presentation to be normal with minimal alteration on Amsler grid testing. A torn ERM was found in the center with left-over ERM temporally and rolled-over ERM nasally at the site of the epicenter with no posterior vitreous detachment. Visual recovery occurred gradually over several days 2 months prior to presentation apparently following heavy weight-lifting with a sensation of severe eye pressure. Sequential funduscopy and optical coherence tomography scans demonstrated the peeling of an ERM accompanied by normalization of foveal thickness. Valsalva maneuver had put excessive tension on ERM which tore in its center at the weakest line with gradual contraction of the ERM away from the fovea towards the peripapillary area. This is a new mechanism of self-separation of ERM induced by Valsalva. ERM in young subjects is subject to rupture and subsequent separation by tangential traction. There are three mechanisms for spontaneous separation of ERM: 1 posterior vitreous detachment with pulling of ERM by detaching vitreous (most common in adults; 2 the contracting forces of the immature ERM become stronger than its adhesions to the retina resulting in slow tangential traction on the

  19. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...... for the lateral organization of membranes as wells as for physical properties like bending, permeability and elasticity...

  20. Induction of Ca2+-dependent cyclosporin A-insensitive nonspecific permeability of the inner membrane of liver mitochondria and cytochrome c release by α,ω-hexadecanedioic acid in media of varying ionic strength.

    Science.gov (United States)

    Dubinin, M V; Vedernikov, A A; Khoroshavina, E I; Samartsev, V N

    2014-06-01

    In liver mitochondria loaded with Ca2+ or Sr(2+), α,ω-hexadecanedioic acid (HDA) can induce nonspecific permeability of the inner membrane (mitochondrial pore) by the mechanism insensitive to cyclosporin A (CsA). In this work we studied the effect of ionic strength of the incubation medium on the kinetics of the processes that accompany Ca2+-dependent induction of the mitochondrial pore by fatty acid: organelle swelling, Ca2+ release from the matrix, changes in transmembrane potential (Δψ) and rate of oxygen consumption, and the release of cytochrome c from the intermembrane space. Two basic incubation media were used: sucrose medium and isotonic ionic medium containing KCl without sucrose. We found that 200 μM Ca2+ and 20 μM HDA in the presence of CsA effectively induce high-amplitude swelling of mitochondria both in the case of sucrose and in the ionic incubation medium. In the presence of CsA, mitochondria can rapidly absorb Ca2+ and retain it in the matrix for a while without reducing Δψ. Upon incubation in the ionic medium, mitochondria retain most of the added Ca2+ in the matrix for a short time without reducing the Δψ. In both cases the addition of HDA to the mitochondria 2 min after the introduction of Ca2+ leads to the rapid release of these ions from the matrix and total drop in Δψ. The mitochondrial swelling induced by Ca2+ and HDA in non-ionic medium is accompanied by almost maximal stimulation of respiration. Under the same conditions, but during incubation of mitochondria in the ionic medium, it is necessary to add cytochrome c for significant stimulation of respiration. The mitochondrial swelling induced by Ca2+ and HDA leads to the release of cytochrome c in a larger amount in the case of ionic medium than for the sucrose medium. We conclude that high ionic strength of the incubation medium determines the massive release of cytochrome c from mitochondria and liberates it from the respiratory chain, which leads to blockade of electron

  1. Skin-safe photothermal therapy enabled by responsive release of acid-activated membrane-disruptive polymer from polydopamine nanoparticle upon very low laser irradiation.

    Science.gov (United States)

    Zhu, Rui; Gao, Feng; Piao, Ji-Gang; Yang, Lihua

    2017-07-25

    How to ablate tumor without damaging skin is a challenge for photothermal therapy. We, herein, report skin-safe photothermal cancer therapy provided by the responsive release of acid-activated hemolytic polymer (aHLP) from the photothermal polydopamine (PDA) nanoparticle upon irradiation at very low dosage. Upon skin-permissible irradiation (via an 850 nm laser irradiation at the power density of 0.4 W cm -2 ), the nanoparticle aHLP-PDA generates sufficient localized-heat to bring about mild hyperthermia treatment and consequently, responsively sheds off the aHLP polymer from its PDA nanocore; this leads to selective cytotoxicity to cancer cells under the acidic conditions of the extracellular microenvironment of tumor. As a result, our aHLP-PDA nanoparticle upon irradiation at a low dosage effectively inhibits tumor growth without damaging skin, as demonstrated using animal models. Effective in mitigating the otherwise inevitable skin damage in tumor photothermal therapy, the nanosystem reported herein offers an efficient pathway towards skin-safe photothermal therapy.

  2. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At Stanford University, Boxer lab, I worked on membrane fusion of small unilamellar lipid vesicles to flat membranes tethered to glass surfaces. This geometry closely resembles biological systems in which liposomes fuse to plasma membranes. The fusion mechanism was studied using DNA zippering...... between complementary strands linked to the two apposing membranes closely mimicking the zippering mechanism of SNARE fusion complexes....

  3. Platelet antiheparin activity. The isolation and characterisation of platelet factor 4 released from thrombin-aggregated washed human platelets and its dissociation into subunits and the isolation of membrane-bound antiheparin activity.

    Science.gov (United States)

    Moore, S; Pepper, D S; Cash, J D

    1975-02-27

    Platelet factor 4 was isolated by gel filtration from the soluble release products of thrombin-aggregated washed human platelets as a proteoglycan-platelet factor 4 complex of molecular weight 358 000, Stokes radius (r-s) of 14.0 nm, sedimentation coefficient (s) of 7.1 S and frictional ratio (f/f-o) of 3.04. The complex was dissociated at high ionic strength (I equals 0.75) and the proteoglycan separated from platelet factor 4 by gel filtration. Platelet factor 4 had a molecular weight of 27 100, r-s of 2.52 nm, s of 2.4 S and f/f-o of 1.26, was insoluble under physiological conditions but readily soluble at pH 3. Under these conditions platelet factor 4 dissociated into four subunits with a molecular weight of 6900, r-s of 1.92 nm, s of 0.8 S, and f/f-o of 1.52. Qualitative N-terminal amino acid analysis showed the presence of glutamic acid or glutamine as the major end group. Platelet factor 4 was compared with protamine sulphate, which has similar biological properties, by electrophoresis at pH 2.2, in which both migrated as single bands but with differing mobility, and by amino acid analysis which showed a more normal distribution of residues than occurred in protamine sulphate. Of the basic amino acids platelet factor 4 (molecular weight 27 100) contained 5.97% arginine, 3.18% histidine, and 12.31% lysine compared to protamine sulphate with 64.2% arginine, 0.6% lysine and no histidine. A partial specific volume (v) of 0.747 was calculated for platelet factor 4 from its amino acid analysis. A membrane fraction with antiheparin activity, an isopycnic density of 1.090-1.110 and r-s of 15-35 nm, was also isolated by sucrose density gradient centrifugation from the ultrasonicated insoluble platelet residue remaining after thrombin-induced aggregation of washed human platelets. Trypsin treatment of the membrane fraction neither solubilised nor destroyed the activity.

  4. ATP Release Channels

    Directory of Open Access Journals (Sweden)

    Akiyuki Taruno

    2018-03-01

    Full Text Available Adenosine triphosphate (ATP has been well established as an important extracellular ligand of autocrine signaling, intercellular communication, and neurotransmission with numerous physiological and pathophysiological roles. In addition to the classical exocytosis, non-vesicular mechanisms of cellular ATP release have been demonstrated in many cell types. Although large and negatively charged ATP molecules cannot diffuse across the lipid bilayer of the plasma membrane, conductive ATP release from the cytosol into the extracellular space is possible through ATP-permeable channels. Such channels must possess two minimum qualifications for ATP permeation: anion permeability and a large ion-conducting pore. Currently, five groups of channels are acknowledged as ATP-release channels: connexin hemichannels, pannexin 1, calcium homeostasis modulator 1 (CALHM1, volume-regulated anion channels (VRACs, also known as volume-sensitive outwardly rectifying (VSOR anion channels, and maxi-anion channels (MACs. Recently, major breakthroughs have been made in the field by molecular identification of CALHM1 as the action potential-dependent ATP-release channel in taste bud cells, LRRC8s as components of VRACs, and SLCO2A1 as a core subunit of MACs. Here, the function and physiological roles of these five groups of ATP-release channels are summarized, along with a discussion on the future implications of understanding these channels.

  5. Membrane Biophysics

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2013-01-01

    Physics, mathematics and chemistry all play a vital role in understanding the true nature and functioning of biological membranes, key elements of living processes. Besides simple spectroscopic observations and electrical measurements of membranes we address in this book the phenomena of coexistence and independent existence of different membrane components using various theoretical approaches. This treatment will be helpful for readers who want to understand biological processes by applying both simple observations and fundamental scientific analysis. It provides a deep understanding of the causes and effects of processes inside membranes, and will thus eventually open new doors for high-level pharmaceutical approaches towards fighting membrane- and cell-related diseases.

  6. Thermo-elasticity and adhesion as regulators of cell membrane architecture and function

    International Nuclear Information System (INIS)

    Sackmann, Erich

    2006-01-01

    Elastic forces and structural phase transitions control the architecture and function of bio-membranes from the molecular to the microscopic scale of organization. The multi-component lipid bilayer matrix behaves as a pseudo-ternary system. Together with elastically and electrostatically mediated specific lipid-protein interaction mechanisms, fluid-fluid phase separation can occur at physiological temperatures. This can drive the transient generation of micro-domains of distinct composition within multi-component lipid-protein alloys, enabling cells to optimize the efficiency of biochemical reactions by facilitating or inhibiting the access of enzymes by distinct substrates or regulatory proteins. Together with global shape changes governed by the principle of minimum bending energy and induced curvature by macromolecular adsorption, phase separation processes can also play a key role for the sorting of lipids and proteins between intracellular compartments during the vesicle mediated intracellular material transport. Cell adhesion is another example of mechanical force controlled membrane processes. By interplay of attractive lock and key forces, long range disjoining pressures mediated by repeller molecules or membrane undulations and elastic interfacial forces, adhesion induced domain formation can play a dual role for the immunological stimulation of lymphocytes and for the rapid control of the adhesion strength. The present picture of the thermo-elastic control of membrane processes based on concepts of local thermal equilibrium is still rudimentary and has to be extended in the future to account for the intrinsic non-equilibrium situation associated with the constant restructuring of the cellular compartments on a timescale of minutes. (topical review)

  7. Radiation curing of intelligent coating for controlled release and permeation

    International Nuclear Information System (INIS)

    Nakayama, Hiroshi; Kaetsu, Isao; Uchida, Kumao; Sakata, Shoei; Tougou, Kazuhide; Hara, Takamichi; Matsubara, Yoshio

    2002-01-01

    Intelligent membranes for pH and temperature-responsive drug releases were developed by coating and curing of polymer-drug composite film with electrolyte or N-isopropyl acrylamide curable mixture. It was proved that those intelligent membranes showed the stimule-sensitive and responsive release functions and could be produced efficiently by radiation curing processing with a conveyer system

  8. Permeability testing of biomaterial membranes

    Energy Technology Data Exchange (ETDEWEB)

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B [NMI Natural and Medical Sciences Institute at University Tuebingen, Markwiesenstr. 55, D-72770 Reutlingen (Germany); Ahlers, M [GELITA AG, Gammelsbacher Str. 2, D-69412 Eberbach (Germany)], E-mail: schlosshauer@nmi.de

    2008-09-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation.

  9. Permeability testing of biomaterial membranes

    International Nuclear Information System (INIS)

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B; Ahlers, M

    2008-01-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation

  10. Membrane paradigm

    International Nuclear Information System (INIS)

    Price, R.H.; Thorne, K.S.

    1986-01-01

    The membrane paradigm is a modified frozen star approach to modeling black holes, with particles and fields assuming a complex, static, boundary-layer type structure (membrane) near the event horizon. The membrane has no effects on the present or future evolution of particles and fields above itself. The mathematical representation is a combination of a formalism containing terms for the shear and bulk viscosity, surface pressure, momentum, temperature, entropy, etc., of the horizon and the 3+1 formalism. The latter model considers a family of three-dimensional spacelike hypersurfaces in one-dimensional time. The membrane model considers a magnetic field threading the hole and undergoing torque from the hole rotation. The field is cleaned by the horizon and distributed over the horizon so that ohmic dissipation is minimized. The membrane paradigm is invalid inside the horizon, but is useful for theoretically probing the properties of slowly evolving black holes

  11. Membrane processes

    Science.gov (United States)

    Staszak, Katarzyna

    2017-11-01

    The membrane processes have played important role in the industrial separation process. These technologies can be found in all industrial areas such as food, beverages, metallurgy, pulp and paper, textile, pharmaceutical, automotive, biotechnology and chemical industry, as well as in water treatment for domestic and industrial application. Although these processes are known since twentieth century, there are still many studies that focus on the testing of new membranes' materials and determining of conditions for optimal selectivity, i. e. the optimum transmembrane pressure (TMP) or permeate flux to minimize fouling. Moreover the researchers proposed some calculation methods to predict the membrane processes properties. In this article, the laboratory scale experiments of membrane separation techniques, as well their validation by calculation methods are presented. Because membrane is the "heart" of the process, experimental and computational methods for its characterization are also described.

  12. Primordial membranes

    DEFF Research Database (Denmark)

    Hanczyc, Martin M; Monnard, Pierre-Alain

    2017-01-01

    Cellular membranes, which are self-assembled bilayer structures mainly composed of lipids, proteins and conjugated polysaccharides, are the defining feature of cell physiology. It is likely that the complexity of contemporary cells was preceded by simpler chemical systems or protocells during...... the various evolutionary stages that led from inanimate to living matter. It is also likely that primitive membranes played a similar role in protocell 'physiology'. The composition of such ancestral membranes has been proposed as mixtures of single hydrocarbon chain amphiphiles, which are simpler versions...

  13. Aggressive re-warming at 38.5 degrees C following deep hypothermia at 21 degrees C increases neutrophil membrane bound elastase activity and pro-inflammatory factor release

    NARCIS (Netherlands)

    Tang, Min; Zhao, Xiao-gang; He, Yi; Gu, Yan; Mei, Ju

    2016-01-01

    Background: Cardiopulmonary bypass (CPB) is often performed under hypothermic condition. The effects of hypothermia and re-warming on neutrophil activity are unclear. This study aimed to compare the effects of different hypothermia and re-warming regimens on neutrophil membrane bound elastase (MBE)

  14. Membranous nephropathy

    Science.gov (United States)

    ... skin-lightening creams Systemic lupus erythematosus , rheumatoid arthritis, Graves disease, and other autoimmune disorders The disorder occurs at ... diagnosis. The following tests can help determine the cause of membranous nephropathy: Antinuclear antibodies test Anti-double- ...

  15. Methane release

    International Nuclear Information System (INIS)

    Seifert, M.

    1999-01-01

    The Swiss Gas Industry has carried out a systematic, technical estimate of methane release from the complete supply chain from production to consumption for the years 1992/1993. The result of this survey provided a conservative value, amounting to 0.9% of the Swiss domestic output. A continuation of the study taking into account new findings with regard to emission factors and the effect of the climate is now available, which provides a value of 0.8% for the target year of 1996. These results show that the renovation of the network has brought about lower losses in the local gas supplies, particularly for the grey cast iron pipelines. (author)

  16. Axionic membranes

    International Nuclear Information System (INIS)

    Aurilia, A.; Spallucci, E.

    1992-01-01

    A metal ring removed from a soap-water solution encloses a film of soap which can be mathematically described as a minimal surface having the ring as its only boundary. This is known to everybody. In this letter we suggest a relativistic extension of the above fluidodynamic system where the soap film is replaced by a Kalb-Ramand gauge potential B μν (x) and the ring by a closed string. The interaction between the B μν field and the string current excites a new configuration of the system consisting of a relativistic membrane bounded by the string. We call such a classical solution of the equation of motion an axionic membrane. As a dynamical system, the axionic membrane admits a Hamilton-Jacobi formulation which is an extension of the HJ theory of electromagnetic strings. (orig.)

  17. Metamaterial membranes

    International Nuclear Information System (INIS)

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2017-01-01

    We introduce a new class of metamaterial device to achieve separation of compounds by using coordinate transformations and metamaterial theory. By rationally designing the spatial anisotropy for mass diffusion, we simultaneously concentrate different compounds in different spatial locations, leading to separation of mixtures across a metamaterial membrane. The separation of mixtures into their constituent compounds is critically important in biophysics, biomedical, and chemical applications. We present a practical case where a mixture of oxygen and nitrogen diffusing through a polymeric planar matrix is separated. This work opens doors to new paradigms in membrane separations via coordinate transformations and metamaterials by introducing novel properties and unconventional mass diffusion phenomena. (paper)

  18. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

    2015-01-01

    microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  19. Stimuli-Responsive Materials for Controlled Release Applications

    KAUST Repository

    Li, Song

    2015-04-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued to guarantee the controlled release of cargo at a specific time and with an accurate amount. Upon applying different stimuli such as light, magnetic field, heat, pH change, enzymes or redox, functional materials change their physicochemical properties through physical transformation or chemical reactions, allowing the release of payload agents on demand. This dissertation studied three stimuli-responsive membrane systems for controlled release from films of macro sizes to microcapsules of nano sizes. The first membrane system is a polymeric composite film which can decrease and sustain diffusion upon light irradiation. The photo-response of membranes is based on the photoreaction of cinnamic derivatives. The second one is composite membrane which can improve diffusion upon heating. The thermo-response of membranes comes from the volume phase transition ability of hydrogels. The third one is microcapsule which can release encapsulated agents upon light irradiation. The photo-response of capsules results from the photoreaction of nitrobenzyl derivatives. The study on these membrane systems reveals that stimuli-responsive release can be achieved by utilizing different functional materials on either macro or micro level. Based on the abundant family of smart materials, designing and fabricating stimuli-responsive systems shall lead to various advanced release processes on demand for biomedical applications.

  20. Model of mouth-to-mouth transfer of bacterial lipoproteins through inner membrane LolC, periplasmic LolA, and outer membrane LolB

    OpenAIRE

    Okuda, Suguru; Tokuda, Hajime

    2009-01-01

    Outer membrane-specific lipoproteins in Escherichia coli are released from the inner membrane by an ATP-binding cassette transporter, the LolCDE complex, which causes the formation of a soluble complex with a periplasmic molecular chaperone, LolA. LolA then transports lipoproteins to the outer membrane where an outer membrane receptor, LolB, incorporates lipoproteins into the outer membrane. The molecular mechanisms underlying the Lol-dependent lipoprotein sorting have been clarified in detai...

  1. Sterilization of heparinized cuprophan hemodialysis membranes

    OpenAIRE

    ten Hoopen, Hermina W.M.; Hinrichs, W.L.J.; Hinrichs, W.L.J.; Engbers, G.H.M.; Feijen, Jan

    1996-01-01

    The effects of sterilization of dry heparinized Cuprophan hemodialysis membranes by means of ethylene oxide (EtO) exposure, gamma irradiation, or steam on the anticoagulant activity and chemical characteristics of immobilized heparin and the permeability of the membrane were investigated. Sterilization did not result in a release of heparin or heparin fragments from heparinized Cuprophan. Sterilization of heparinized Cuprophan by means of EtO exposure and gamma irradiation induced a slight, i...

  2. SNX9 - a prelude to vesicle release.

    Science.gov (United States)

    Lundmark, Richard; Carlsson, Sven R

    2009-01-01

    The sorting nexin SNX9 has, in the past few years, been singled out as an important protein that participates in fundamental cellular activities. SNX9 binds strongly to dynamin and is partly responsible for the recruitment of this GTPase to sites of endocytosis. SNX9 also has a high capacity for modulation of the membrane and might therefore participate in the formation of the narrow neck of endocytic vesicles before scission occurs. Once assembled on the membrane, SNX9 stimulates the GTPase activity of dynamin to facilitate the scission reaction. It has also become clear that SNX9 has the ability to activate the actin regulator N-WASP in a membrane-dependent manner to coordinate actin polymerization with vesicle release. In this Commentary, we summarize several aspects of SNX9 structure and function in the context of membrane remodeling, discuss its interplay with various interaction partners and present a model of how SNX9 might work in endocytosis.

  3. News/Press Releases

    Data.gov (United States)

    Office of Personnel Management — A press release, news release, media release, press statement is written communication directed at members of the news media for the purpose of announcing programs...

  4. Release rate of diazinon from microcapsule based on melamine formaldehyde

    Science.gov (United States)

    Noviana Utami C., S.; Rochmadi

    2018-04-01

    The microcapsule containing diazinon as the core material and melamine formaldehyde as the membrane material have been synthesized by in situ polymerization method. The microcapsule membrane in this research is melamine formaldehyde (MF). This research aims to study the effect of pH and temperature on the release rate of diazinon from microcapsule based on melamine formaldehyde in aqueous medium. The results showed that pH and temperature has little effect on the release rate of diazinon from microcapsule based on melamine formaldehyde. This is due to the diffusion through the microcapsule membrane is not influenced by the pH and temperature of the solution outside of microcapsule.

  5. Robotic membranes

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette

    2008-01-01

    The relationship between digital and analogue is often constructed as one of opposition. The perception that the world is permeated with underlying patterns of data, describing events and matter alike, suggests that information can be understood apart from the substance to which it is associated......, and that its encoded logic can be constructed and reconfigured as an isolated entity. This disembodiment of information from materiality implies that an event like a thunderstorm, or a material like a body, can be described equally by data, in other words it can be read or written. The following prototypes......, Vivisection and Strange Metabolisms, were developed at the Centre for Information Technology and Architecture (CITA) at the Royal Danish Academy of Fine Arts in Copenhagen as a means of engaging intangible digital data with tactile physical material. As robotic membranes, they are a dual examination...

  6. Etched ion track polymer membranes for sustained drug delivery

    International Nuclear Information System (INIS)

    Rao, Vijayalakshmi; Amar, J.V.; Avasthi, D.K.; Narayana Charyulu, R.

    2003-01-01

    The method of track etching has been successfully used for the production of polymer membranes with capillary pores. In the present paper, micropore membranes have been prepared by swift heavy ion irradiation of polycarbonate (PC). PC films were irradiated with ions of gold, silicon and oxygen of varying energies and fluence. The ion tracks thus obtained were etched chemically for various time intervals to get pores and these etched films were used as membranes for the drug release. Ciprofloxacine hydrochloride was used as model drug for the release studies. The drug content was estimated spectrophotometrically. Pore size and thus the drug release is dependent on the etching conditions, ions used, their energy and fluence. Sustained drug release has been observed in these membranes. The films can be selected for practical utilization by optimizing the irradiation and etching conditions. These films can be used as transdermal patches after medical treatment

  7. Biogenesis and Membrane Targeting of Lipoproteins.

    Science.gov (United States)

    Narita, Shin-Ichiro; Tokuda, Hajime

    2010-09-01

    Bacterial lipoproteins represent a unique class of membrane proteins, which are anchored to membranes through triacyl chains attached to the amino-terminal cysteine. They are involved in various functions localized in cell envelope. Escherichia coli possesses more than 90 species of lipoproteins, most of which are localized in the outer membrane, with others being in the inner membrane. All lipoproteins are synthesized in the cytoplasm with an N-terminal signal peptide, translocated across the inner membrane by the Sec translocon to the periplasmic surface of the inner membrane, and converted to mature lipoproteins through sequential reactions catalyzed by three lipoprotein-processing enzymes: Lgt, LspA, and Lnt. The sorting of lipoproteins to the outer membrane requires a system comprising five Lol proteins. An ATP-binding cassette transporter, LolCDE, initiates the sorting by mediating the detachment of lipoproteins from the inner membrane. Formation of the LolA-lipoprotein complex is coupled to this LolCDE-dependent release reaction. LolA accommodates the amino-terminal acyl chain of lipoproteins in its hydrophobic cavity, thereby generating a hydrophilic complex that can traverse the periplasmic space by diffusion. Lipoproteins are then transferred to LolB on the outer membrane and anchored to the inner leaflet of the outer membrane by the action of LolB. In contrast, since LolCDE does not recognize lipoproteins possessing Asp at position +2, these lipoproteins remain anchored to the inner membrane. Genes for Lol proteins are widely conserved among gram-negative bacteria, and Lol-mediated outer membrane targeting of lipoproteins is considered to be the general lipoprotein localization mechanism.

  8. Extracellular vesicle-mediated phenotype switching in malignant and non-malignant colon cells

    International Nuclear Information System (INIS)

    Mulvey, Hillary E.; Chang, Audrey; Adler, Jason; Del Tatto, Michael; Perez, Kimberly; Quesenberry, Peter J.; Chatterjee, Devasis

    2015-01-01

    Extracellular vesicles (EVs) are secreted from many cells, carrying cargoes including proteins and nucleic acids. Research has shown that EVs play a role in a variety of biological processes including immunity, bone formation and recently they have been implicated in promotion of a metastatic phenotype. EVs were isolated from HCT116 colon cancer cells, 1459 non-malignant colon fibroblast cells, and tumor and normal colon tissue from a patient sample. Co-cultures were performed with 1459 cells and malignant vesicles, as well as HCT116 cells and non-malignant vesicles. Malignant phenotype was measured using soft agar colony formation assay. Co-cultures were also analyzed for protein levels using mass spectrometry. The importance of 14-3-3 zeta/delta in transfer of malignant phenotype was explored using siRNA. Additionally, luciferase reporter assay was used to measure the transcriptional activity of NF-κB. This study demonstrates the ability of EVs derived from malignant colon cancer cell line and malignant patient tissue to induce the malignant phenotype in non-malignant colon cells. Similarly, EVs derived from non-malignant colon cell lines and normal patient tissue reversed the malignant phenotype of HCT116 cells. Cells expressing an EV-induced malignant phenotype showed increased transcriptional activity of NF-κB which was inhibited by the NF--κB inhibitor, BAY117082. We also demonstrate that knock down of 14-3-3 zeta/delta reduced anchorage-independent growth of HCT116 cells and 1459 cells co-cultured with HCT derived EVs. Evidence of EV-mediated induction of malignant phenotype, and reversal of malignant phenotype, provides rational basis for further study of the role of EVs in tumorigenesis. Identification of 14-3-3 zeta/delta as up-regulated in malignancy suggests its potential as a putative drug target for the treatment of colorectal cancer

  9. Recent advances on polymeric membranes for membrane reactors

    KAUST Repository

    Buonomenna, M. G.; Choi, Seung Hak

    2012-01-01

    . The successful use of membranes in membrane reactors is primary the result of two developments concerning: (i) membrane materials and (ii) membrane structures. The selection of a suited material and preparation technique depends on the application the membrane

  10. Magnetically controlled permeability membranes

    KAUST Repository

    Kosel, Jurgen

    2013-10-31

    A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

  11. Magnetically controlled permeability membranes

    KAUST Repository

    Kosel, Jü rgen; Khashab, Niveen M.; Zaher, Amir

    2013-01-01

    A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

  12. Sorting of bacterial lipoproteins to the outer membrane by the Lol system.

    Science.gov (United States)

    Narita, Shin-ichiro; Tokuda, Hajime

    2010-01-01

    Bacterial lipoproteins comprise a subset of membrane proteins with a lipid-modified cysteine residue at their amino termini through which they are anchored to the membrane. In Gram-negative bacteria, lipoproteins are localized on either the inner or the outer membrane. The Lol system is responsible for the transport of lipoproteins to the outer membrane.The Lol system comprises an inner-membrane ABC transporter LolCDE complex, a periplasmic carrier protein, LolA, and an outer membrane receptor protein, LolB. Lipoproteins are synthesized as precursors in the cytosol and then translocated across the inner membrane by the Sec translocon to the outer leaflet of the inner membrane, where lipoprotein precursors are processed to mature lipoproteins. The LolCDE complex then mediates the release of outer membrane-specific lipoproteins from the inner membrane while the inner membrane-specific lipoproteins possessing Asp at position 2 are not released by LolCDE because it functions as a LolCDE avoidance signal, causing the retention of these lipoproteins in the inner membrane. A water-soluble lipoprotein-LolA complex is formed as a result of the release reaction mediated by LolCDE. This complex traverses the hydrophilic periplasm to reach the outer membrane, where LolB accepts a lipoprotein from LolA and then catalyzes its incorporation into the inner leaflet of the outer membrane.

  13. Application of new nuclear track microporous membrane in transdermal therapeutic system (TTS)

    International Nuclear Information System (INIS)

    Risheng Wu; Jian Zhou; Wei Ke

    1993-01-01

    Newly-developed Nuclear Track Microporous Membrane, which is formed by alpha particle irradiation with greatly reduced cost, is first used as the drug release rate controlling membrane for TTS patch. It shows good zero order release kinetics and its released quantity of drugs can be regulated conveniently by changing its porosity instead of changing the area of other control membrane used abroad. Its high benefit-cost ratio and improved TTS performances manifest the superiority and great potential of the newly developed Nuclear Track Microporous membrane. (Author)

  14. Dynamic coating of mf/uf membranes for fouling mitigation

    KAUST Repository

    Tabatabai, S. Assiyeh Alizadeh

    2017-01-19

    A membrane system including an anti-fouling layer and a method of applying an anti-fouling layer to a membrane surface are provided. In an embodiment, the surface is a microfiltration (MF) or an ultrafiltration (UF) membrane surface. The anti-fouling layer can include a stimuli responsive layer and a dynamic protective layer applied over the stimuli responsive layer that can be a coating on a surface of the membrane. The stimuli responsive polymer layer can act as an adhesive prior to coating with the dynamic protective layer to aid in adhering the dynamic protective layer to the membrane surface. The dynamic protective layer can be formed by suitable nanoparticles that can prevent adhesion of foulants directly to the membrane surface. The stimuli responsive layer can be responsive to physio- chemical stimuli to cause a release of the stimuli responsive layer and the dynamic protective layer including foulants from the membrane.

  15. Toxics Release Inventory (TRI)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Toxics Release Inventory (TRI) is a dataset compiled by the U.S. Environmental Protection Agency (EPA). It contains information on the release and waste...

  16. Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Stoica-Guzun, Anicuta [Department of Chemical Engineering, ' Politehnica' University Bucharest, 313 Splaiul Independentei, 060042 Bucharest (Romania)], E-mail: astoica@mt.pub.ro; Stroescu, Marta; Tache, Florin [Department of Chemical Engineering, ' Politehnica' University Bucharest, 313 Splaiul Independentei, 060042 Bucharest (Romania); Zaharescu, Traian [Advanced Research Institute for Electrical Engineering, 313 Splaiul Unirii, 030138 Bucharest (Romania)], E-mail: zaharescut@icpe-ca.ro; Grosu, Elena [Department of Chemical Engineering, ' Politehnica' University Bucharest, 313 Splaiul Independentei, 060042 Bucharest (Romania)

    2007-12-15

    Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of {gamma}-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell.

  17. Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

    International Nuclear Information System (INIS)

    Stoica-Guzun, Anicuta; Stroescu, Marta; Tache, Florin; Zaharescu, Traian; Grosu, Elena

    2007-01-01

    Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of γ-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell

  18. Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

    Science.gov (United States)

    Stoica-Guzun, Anicuta; Stroescu, Marta; Tache, Florin; Zaharescu, Traian; Grosu, Elena

    2007-12-01

    Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of γ-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell.

  19. Cargo Release from Polymeric Vesicles under Shear

    Directory of Open Access Journals (Sweden)

    Yingying Guo

    2018-03-01

    Full Text Available In this paper we study the release of cargo from polymeric nano-carriers under shear. Vesicles formed by two star block polymers— A 12 B 6 C 2 ( A B C and A 12 B 6 A 2 ( A B A —and one linear block copolymer— A 14 B 6 ( A B , are investigated using dissipative particle dynamics (DPD simulations. A - and C -blocks are solvophobic and B -block is solvophilic. The three polymers form vesicles of different structures. The vesicles are subjected to shear both in bulk and between solvophobic walls. In bulk shear, the mechanisms of cargo release are similar for all vesicles, with cargo travelling through vesicle membrane with no preferential release location. When sheared between walls, high cargo release rate is only observed with A B C vesicle after it touches the wall. For A B C vesicle, the critical condition for high cargo release rate is the formation of wall-polymersome interface after which the effect of shear rate in promoting cargo release is secondary. High release rate is achieved by the formation of solvophilic pathway allowing cargo to travel from the vesicle cavity to the vesicle exterior. The results in this paper show that well controlled target cargo release using polymersomes can be achieved with polymers of suitable design and can potentially be very useful for engineering applications. As an example, polymersomes can be used as carriers for surface active friction reducing additives which are only released at rubbing surfaces where the additives are needed most.

  20. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T [Huntington Beach, CA; Sahimi, Muhammad [Altadena, CA; Fayyaz-Najafi, Babak [Richmond, CA; Harale, Aadesh [Los Angeles, CA; Park, Byoung-Gi [Yeosu, KR; Liu, Paul K. T. [Lafayette Hill, PA

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  1. Premature rupture of membranes

    Science.gov (United States)

    ... gov/ency/patientinstructions/000512.htm Premature rupture of membranes To use the sharing features on this page, ... water that surrounds your baby in the womb. Membranes or layers of tissue hold in this fluid. ...

  2. Oxygen transport membrane

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof.......The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof....

  3. Membrane with integrated spacer

    NARCIS (Netherlands)

    Balster, J.H.; Stamatialis, Dimitrios; Wessling, Matthias

    2010-01-01

    Many membrane processes are severely influenced by concentration polarisation. Turbulence promoting spacers placed in between the membranes can reduce the diffusional resistance of concentration polarisation by inducing additional mixing. Electrodialysis (ED) used for desalination suffers from

  4. Silver nanoparticles delivery system based on natural rubber latex membranes

    International Nuclear Information System (INIS)

    Guidelli, Éder José; Kinoshita, Angela; Ramos, Ana Paula; Baffa, Oswaldo

    2013-01-01

    The search for new materials for biomedical applications is extremely important. Here, we present results on the performance of a silver nanoparticles delivery system using natural rubber latex (NRL) as the polymeric matrix. Our aim was to obtain an optimized wound dressing by combining materials with potential healing action. The synthesis of silver nanoparticles and their characterization by UV–Vis spectroscopy, transmission electron microscopy, zeta potential, dynamic light scattering, and Fourier transform infrared spectroscopy (FTIR) are depicted. The NRL membranes are good matrix for silver nanoparticles and allow for their gradual release. The release of 30 nm silver nanoparticles by the NRL membranes depends on their mass percentage in NRL membranes. The total concentration of AgNP released by the NRL membranes was calculated. The AgNP attached to the cis-isoprene molecules in the NRL matrix remain attached to the membrane (∼0.1 % w/w). So, only the AgNP bound to the non-rubber molecules are released. FTIR spectra suggest that non-rubber molecules, like aminoacids and proteins, associated with the serum fraction of the NRL may be attached to the surfaces of the released nanoparticles, thereby increasing the release of such molecules. The released silver nanoparticles are sterically stabilized, more stable and well dispersed. Because the serum fraction of the NRL is responsible for the angiogenic properties of the matrix, the silver nanoparticles could increment the angiogenic properties of NRL. This biomaterial has desirable properties for the fabrication of a wound dressing with potential healing action, since it combines the angiogenic and antibacterial properties of the silver nanoparticles with the increased angiogenic properties of the NRL.Graphical AbstractThe AgNP attached to the cis-isoprene molecules remain in the NRL matrix and only the AgNP bound to the non-rubber molecules (NRL serum fraction) are released. The released AgNP are sterically

  5. Silver nanoparticles delivery system based on natural rubber latex membranes

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, Eder Jose, E-mail: ederguidelli@gmail.com [Universidade de Sao Paulo/FFCLRP-DF (Brazil); Kinoshita, Angela [Universidade do Sagrado Coracao (Brazil); Ramos, Ana Paula [Universidade de Sao Paulo/FFCLRP-DQ (Brazil); Baffa, Oswaldo [Universidade de Sao Paulo/FFCLRP-DF (Brazil)

    2013-04-15

    The search for new materials for biomedical applications is extremely important. Here, we present results on the performance of a silver nanoparticles delivery system using natural rubber latex (NRL) as the polymeric matrix. Our aim was to obtain an optimized wound dressing by combining materials with potential healing action. The synthesis of silver nanoparticles and their characterization by UV-Vis spectroscopy, transmission electron microscopy, zeta potential, dynamic light scattering, and Fourier transform infrared spectroscopy (FTIR) are depicted. The NRL membranes are good matrix for silver nanoparticles and allow for their gradual release. The release of 30 nm silver nanoparticles by the NRL membranes depends on their mass percentage in NRL membranes. The total concentration of AgNP released by the NRL membranes was calculated. The AgNP attached to the cis-isoprene molecules in the NRL matrix remain attached to the membrane ({approx}0.1 % w/w). So, only the AgNP bound to the non-rubber molecules are released. FTIR spectra suggest that non-rubber molecules, like aminoacids and proteins, associated with the serum fraction of the NRL may be attached to the surfaces of the released nanoparticles, thereby increasing the release of such molecules. The released silver nanoparticles are sterically stabilized, more stable and well dispersed. Because the serum fraction of the NRL is responsible for the angiogenic properties of the matrix, the silver nanoparticles could increment the angiogenic properties of NRL. This biomaterial has desirable properties for the fabrication of a wound dressing with potential healing action, since it combines the angiogenic and antibacterial properties of the silver nanoparticles with the increased angiogenic properties of the NRL.Graphical AbstractThe AgNP attached to the cis-isoprene molecules remain in the NRL matrix and only the AgNP bound to the non-rubber molecules (NRL serum fraction) are released. The released AgNP are

  6. Gel layer formation on membranes in Membrane Bioreactors

    NARCIS (Netherlands)

    Van den Brink, P.F.H.

    2014-01-01

    The widespread application of membrane bioreactors (MBRs) for municipal wastewater treatment is hampered by membrane fouling. Fouling increases energy demand, reduces process performance and creates the need for more frequent (chemical) membrane cleaning or replacement. Membrane fouling in MBRs is

  7. Smart membranes for monitoring membrane based desalination processes

    KAUST Repository

    Laleg-Kirati, Taous-Meriem; Karam, Ayman M.

    2017-01-01

    Various examples are related to smart membranes for monitoring membrane based process such as, e.g., membrane distillation processes. In one example, a membrane, includes a porous surface and a plurality of sensors (e.g., temperature, flow and

  8. In-vitro Degradation Behaviour of Irradiated Bacterial Cellulose Membrane

    International Nuclear Information System (INIS)

    Darwis, D.; Khusniya, T.; Hardiningsih, L.; Nurlidar, F.; Winarno, H.

    2012-01-01

    Bacterial cellulose membrane synthesized by Acetobacter xylinum in coconut water medium has potential application for Guided bone Regeneration. However, this membrane may not meet some application requirements due to its low biodegradation properties. In this paper, incorporation of gamma irradiation into the membrane is a developed strategy to increase its biodegradability properties. The in-vitro degradation study in synthetic body fluid (SBF) of the irradiated membrane has been analyzed during periods of 6 months by means of weight loss, mechanical properties and scanning electron microscopy observation compared to that the un-irradiated one. The result showed that weight loss of irradiated membrane with 25 kGy and 50 kGy and immersed in SBF solution for 6 months reached 18% and 25% respectively. While un-irradiated membrane did not give significant weight loss. Tensile strength of membranes decreases with increasing of irradiation dose and further decreases in tensile strength is observed when irradiated membrane was followed by immersion in SBF solution. Microscope electron image of cellulose membranes shows that un-irradiated bacterial cellulose membrane consists of dense ultrafine fibril network structures, while irradiation result in cleavage of fibrils network of cellulose. The fibrils network become loosely after irradiated membrane immersed in SBF solution due to released of small molecular weight carbohydrates formed during by irradiation from the structure (author)

  9. Vesicular and Plasma Membrane Transporters for Neurotransmitters

    Science.gov (United States)

    Blakely, Randy D.; Edwards, Robert H.

    2012-01-01

    The regulated exocytosis that mediates chemical signaling at synapses requires mechanisms to coordinate the immediate response to stimulation with the recycling needed to sustain release. Two general classes of transporter contribute to release, one located on synaptic vesicles that loads them with transmitter, and a second at the plasma membrane that both terminates signaling and serves to recycle transmitter for subsequent rounds of release. Originally identified as the target of psychoactive drugs, these transport systems have important roles in transmitter release, but we are only beginning to understand their contribution to synaptic transmission, plasticity, behavior, and disease. Recent work has started to provide a structural basis for their activity, to characterize their trafficking and potential for regulation. The results indicate that far from the passive target of psychoactive drugs, neurotransmitter transporters undergo regulation that contributes to synaptic plasticity. PMID:22199021

  10. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite

    2014-01-01

    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes control...

  11. Idiopathic epiretinal membrane

    NARCIS (Netherlands)

    Bu, Shao-Chong; Kuijer, Roelof; Li, Xiao-Rong; Hooymans, Johanna M M; Los, Leonoor I

    2014-01-01

    Background: Idiopathic epiretinal membrane (iERM) is a fibrocellular membrane that proliferates on the inner surface of the retina at the macular area. Membrane contraction is an important sight-threatening event and is due to fibrotic remodeling. Methods: Analysis of the current literature

  12. Meniscus Membranes For Separation

    Science.gov (United States)

    Dye, Robert C.; Jorgensen, Betty; Pesiri, David R.

    2005-09-20

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  13. Meniscus membranes for separations

    Science.gov (United States)

    Dye, Robert C [Irvine, CA; Jorgensen, Betty [Jemez Springs, NM; Pesiri, David R [Aliso Viejo, CA

    2004-01-27

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  14. Separation membrane development

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.W. [Savannah River Technology Center, Aiken, SC (United States)

    1998-08-01

    A ceramic membrane has been developed to separate hydrogen from other gases. The method used is a sol-gel process. A thin layer of dense ceramic material is coated on a coarse ceramic filter substrate. The pore size distribution in the thin layer is controlled by a densification of the coating materials by heat treatment. The membrane has been tested by permeation measurement of the hydrogen and other gases. Selectivity of the membrane has been achieved to separate hydrogen from carbon monoxide. The permeation rate of hydrogen through the ceramic membrane was about 20 times larger than Pd-Ag membrane.

  15. Microporous silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng

    2012-01-01

    Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions...... on the microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

  16. Clustering on Membranes

    DEFF Research Database (Denmark)

    Johannes, Ludger; Pezeshkian, Weria; Ipsen, John H

    2018-01-01

    Clustering of extracellular ligands and proteins on the plasma membrane is required to perform specific cellular functions, such as signaling and endocytosis. Attractive forces that originate in perturbations of the membrane's physical properties contribute to this clustering, in addition to direct...... protein-protein interactions. However, these membrane-mediated forces have not all been equally considered, despite their importance. In this review, we describe how line tension, lipid depletion, and membrane curvature contribute to membrane-mediated clustering. Additional attractive forces that arise...... from protein-induced perturbation of a membrane's fluctuations are also described. This review aims to provide a survey of the current understanding of membrane-mediated clustering and how this supports precise biological functions....

  17. Application of dynamic membranes in anaerobic membranes in anaerobic membrane bioreactor systems

    NARCIS (Netherlands)

    Erşahin, M.E.

    2015-01-01

    Anaerobic membrane bioreactors (AnMBRs) physically ensure biomass retention by the application of a membrane filtration process. With growing application experiences from aerobic membrane bioreactors (MBRs), the combination of membrane and anaerobic processes has received much attention and become

  18. Large scientific releases

    International Nuclear Information System (INIS)

    Pongratz, M.B.

    1981-01-01

    The motivation for active experiments in space is considered, taking into account the use of active techniques to obtain a better understanding of the natural space environment, the utilization of the advantages of space as a laboratory to study fundamental plasma physics, and the employment of active techniques to determine the magnitude, degree, and consequences of artificial modification of the space environment. It is pointed out that mass-injection experiments in space plasmas began about twenty years ago with the Project Firefly releases. Attention is given to mass-release techniques and diagnostics, operational aspects of mass release active experiments, the active observation of mass release experiments, active perturbation mass release experiments, simulating an artificial modification of the space environment, and active experiments to study fundamental plasma physics

  19. Antifouling membranes for sustainable water purification: strategies and mechanisms.

    Science.gov (United States)

    Zhang, Runnan; Liu, Yanan; He, Mingrui; Su, Yanlei; Zhao, Xueting; Elimelech, Menachem; Jiang, Zhongyi

    2016-10-24

    One of the greatest challenges to the sustainability of modern society is an inadequate supply of clean water. Due to its energy-saving and cost-effective features, membrane technology has become an indispensable platform technology for water purification, including seawater and brackish water desalination as well as municipal or industrial wastewater treatment. However, membrane fouling, which arises from the nonspecific interaction between membrane surface and foulants, significantly impedes the efficient application of membrane technology. Preparing antifouling membranes is a fundamental strategy to deal with pervasive fouling problems from a variety of foulants. In recent years, major advancements have been made in membrane preparation techniques and in elucidating the antifouling mechanisms of membrane processes, including ultrafiltration, nanofiltration, reverse osmosis and forward osmosis. This review will first introduce the major foulants and the principal mechanisms of membrane fouling, and then highlight the development, current status and future prospects of antifouling membranes, including antifouling strategies, preparation techniques and practical applications. In particular, the strategies and mechanisms for antifouling membranes, including passive fouling resistance and fouling release, active off-surface and on-surface strategies, will be proposed and discussed extensively.

  20. Probing lipid membrane electrostatics

    Science.gov (United States)

    Yang, Yi

    The electrostatic properties of lipid bilayer membranes play a significant role in many biological processes. Atomic force microscopy (AFM) is highly sensitive to membrane surface potential in electrolyte solutions. With fully characterized probe tips, AFM can perform quantitative electrostatic analysis of lipid membranes. Electrostatic interactions between Silicon nitride probes and supported zwitterionic dioleoylphosphatidylcholine (DOPC) bilayer with a variable fraction of anionic dioleoylphosphatidylserine (DOPS) were measured by AFM. Classical Gouy-Chapman theory was used to model the membrane electrostatics. The nonlinear Poisson-Boltzmann equation was numerically solved with finite element method to provide the potential distribution around the AFM tips. Theoretical tip-sample electrostatic interactions were calculated with the surface integral of both Maxwell and osmotic stress tensors on tip surface. The measured forces were interpreted with theoretical forces and the resulting surface charge densities of the membrane surfaces were in quantitative agreement with the Gouy-Chapman-Stern model of membrane charge regulation. It was demonstrated that the AFM can quantitatively detect membrane surface potential at a separation of several screening lengths, and that the AFM probe only perturbs the membrane surface potential by external field created by the internai membrane dipole moment. The analysis yields a dipole moment of 1.5 Debye per lipid with a dipole potential of +275 mV for supported DOPC membranes. This new ability to quantitatively measure the membrane dipole density in a noninvasive manner will be useful in identifying the biological effects of the dipole potential. Finally, heterogeneous model membranes were studied with fluid electric force microscopy (FEFM). Electrostatic mapping was demonstrated with 50 nm resolution. The capabilities of quantitative electrostatic measurement and lateral charge density mapping make AFM a unique and powerful

  1. Emulsification using microporous membranes

    Directory of Open Access Journals (Sweden)

    Goran T. Vladisavljević

    2011-10-01

    Full Text Available Membrane emulsification is a process of injecting a pure dispersed phase or pre-emulsion through a microporous membrane into the continuous phase. As a result of the immiscibility of the two phases, droplets of the dispersed phase are formed at the outlets of membrane pores. The droplets formed in the process are removed from the membrane surface by applying cross-flow or stirring of the continuous phase or using a dynamic (rotating or vibrating membrane. The most commonly used membrane for emulsification is the Shirasu Porous Glass (SPG membrane, fabricated through spinodal decomposition in a melt consisting of Japanese volcanic ash (Shirasu, boric acid and calcium carbonate. Microsieve membranes are increasingly popular as an alternative to highly tortuous glass and ceramic membranes. Microsieves are usually fabricated from nickel by photolithography and electroplating or they can be manufactured from silicon nitride via Reactive Ion Etching (RIE. An advantage of microsieves compared to the SPG membrane is in much higher transmembrane fluxes and higher tolerance to fouling by the emulsion ingredients due to the existence of short, straight through pores. Unlike conventional emulsification devices such as high-pressure valve homogenisers and rotor-stator devices, membrane emulsification devices permit a precise control over the mean pore size over a wide range and during the process insignificant amount of energy is dissipated as heat. The drop size is primarily determined by the pore size, but it depends also on other parameters, such as membrane wettability, emulsion formulation, shear stress on the membrane surface, transmembrane pressure, etc.

  2. Ion-conducting membranes

    Science.gov (United States)

    Masel, Richard I.; Sajjad, Syed Dawar; Gao, Yan; Liu, Zengcai; Chen, Qingmei

    2017-12-26

    An anion-conducting polymeric membrane comprises a terpolymer of styrene, vinylbenzyl-R.sub.s and vinylbenzyl-R.sub.x. R.sub.s is a positively charged cyclic amine group. R.sub.x is at least one constituent selected from the group consisting Cl, OH and a reaction product between an OH or Cl and a species other than a simple amine or a cyclic amine. The total weight of the vinylbenzyl-R.sub.x groups is greater than 0.3% of the total weight of the membrane. In a preferred embodiment, the membrane is a Helper Membrane that increases the faradaic efficiency of an electrochemical cell into which the membrane is incorporated, and also allows product formation at lower voltages than in cells without the Helper Membrane.

  3. Gas separation with membranes

    International Nuclear Information System (INIS)

    Schulz, G.; Michele, H.; Werner, U.

    1982-01-01

    Gas separation with membranes has already been tested in numerous fields of application, e.g. uranium enrichment of H 2 separation. In many of these processes the mass transfer units, so-called permeators, have to be connected in tandem in order to achieve high concentrations. A most economical operating method provides for each case an optimization of the cascades with regard to the membrane materials, construction and design of module. By utilization of the concentration gradient along the membrane a new process development has been accomplished - the continuously operating membrane rectification unit. Investment and operating costs can be reduced considerably for a number of separating processes by combining a membrane rectification unit with a conventional recycling cascade. However, the new procedure requires that the specifications for the module construction, flow design, and membrane properties be reconsidered. (orig.) [de

  4. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  5. Gas separation membranes

    Science.gov (United States)

    Schell, William J.

    1979-01-01

    A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

  6. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  7. Photoresponsive nanostructured membranes

    KAUST Repository

    Madhavan, Poornima

    2016-07-26

    The perspective of adding stimuli-response to isoporous membranes stimulates the development of separation devices with pores, which would open or close under control of environment chemical composition, temperature or exposure to light. Changes in pH and temperature have been previously investigated. In this work, we demonstrate for the first time the preparation of photoresponsive isoporous membranes, applying self-assembly non-solvent induced phase separation to a new light responsive block copolymer. First, we optimized the membrane formation by using poly(styrene-b-anthracene methyl methacrylate-b-methylmethacrylate) (PS-b-PAnMMA-b-PMMA) copolymer, identifying the most suitable solvent, copolymer block length, and other parameters. The obtained final triblock copolymer membrane morphologies were characterized using atomic force and electron microscopy. The microscopic analysis reveals that the PS-b-PAnMMA-b-PMMA copolymer can form both lamellar and ordered hexagonal nanoporous structures on the membrane top layer in appropriate solvent compositions. The nanostructured membrane emits fluorescence due to the presence of the anthracene mid-block. On irradiation of light the PS-b-PAnMMA-b-PMMA copolymer membranes has an additional stimuli response. The anthracene group undergoes conformational changes by forming [4 + 4] cycloadducts and this alters the membrane\\'s water flux and solute retention. © 2016 The Royal Society of Chemistry.

  8. The establishment of polarized membrane traffic in Xenopus laevis embryos.

    Science.gov (United States)

    Roberts, S J; Leaf, D S; Moore, H P; Gerhart, J C

    1992-09-01

    Delineation of apical and basolateral membrane domains is a critical step in the epithelialization of the outer layer of cells in the embryo. We have examined the initiation of polarized membrane traffic in Xenopus and show that membrane traffic is not polarized in oocytes but polarized membrane domains appear at first cleavage. The following proteins encoded by injected RNA transcripts were used as markers to monitor membrane traffic: (a) VSV G, a transmembrane glycoprotein preferentially inserted into the basolateral surface of polarized epithelial cells; (b) GThy-1, a fusion protein of VSV G and Thy-1 that is localized to the apical domains of polarized epithelial cells; and (c) prolactin, a peptide hormone that is not polarly secreted. In immature oocytes, there is no polarity in the expression of VSV G or GThy-1, as shown by the constitutive expression of both proteins at the surface in the animal and vegetal hemispheres. At meiotic maturation, membrane traffic to the surface is blocked; the plasma membrane no longer accepts the vesicles synthesized by the oocyte (Leaf, D. L., S. J. Roberts, J. C. Gerhart, and H.-P. Moore. 1990. Dev. Biol. 141:1-12). When RNA transcripts are injected after fertilization, VSV G is expressed only in the internal cleavage membranes (basolateral orientation) and is excluded from the outer surface (apical orientation, original oocyte membrane). In contrast, GThy-1 and prolactin, when expressed in embryos, are inserted or released at both the outer membrane derived from the oocyte and the inner cleavage membranes. Furthermore, not all of the cleavage membrane comes from an embryonic pool of vesicles--some of the cleavage membrane comes from vesicles synthesized during oogenesis. Using prolactin as a marker, we found that a subset of vesicles synthesized during oogenesis was only released after fertilization. However, while embryonic prolactin was secreted from both apical and basolateral surfaces, the secretion of oogenic prolactin

  9. The 2017 Release Cloudy

    Science.gov (United States)

    Ferland, G. J.; Chatzikos, M.; Guzmán, F.; Lykins, M. L.; van Hoof, P. A. M.; Williams, R. J. R.; Abel, N. P.; Badnell, N. R.; Keenan, F. P.; Porter, R. L.; Stancil, P. C.

    2017-10-01

    We describe the 2017 release of the spectral synthesis code Cloudy, summarizing the many improvements to the scope and accuracy of the physics which have been made since the previous release. Exporting the atomic data into external data files has enabled many new large datasets to be incorporated into the code. The use of the complete datasets is not realistic for most calculations, so we describe the limited subset of data used by default, which predicts significantly more lines than the previous release of Cloudy. This version is nevertheless faster than the previous release, as a result of code optimizations. We give examples of the accuracy limits using small models, and the performance requirements of large complete models. We summarize several advances in the H- and He-like iso-electronic sequences and use our complete collisional-radiative models to establish the densities where the coronal and local thermodynamic equilibrium approximations work.

  10. EIA new releases

    International Nuclear Information System (INIS)

    1994-09-01

    This report is a compliation of news releases from the Energy Information Administration. The september-october report includes articles on energy conservation, energy consumption in commercial buildings, and a short term energy model for a personal computer

  11. Sellafield (release of radioactivity)

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, J; Goodlad, A; Morris, M

    1986-02-06

    A government statement is reported, about the release of plutonium nitrate at the Sellafield site of British Nuclear Fuels plc on 5 February 1986. Matters raised included: details of accident; personnel monitoring; whether radioactive material was released from the site; need for public acceptance of BNFL activities; whether plant should be closed; need to reduce level of radioactive effluent; number of incidents at the plant.

  12. Sustained Administration of Hormones Exploiting Nanoconfined Diffusion through Nanochannel Membranes

    Directory of Open Access Journals (Sweden)

    Thomas Geninatti

    2015-08-01

    Full Text Available Implantable devices may provide a superior means for hormone delivery through maintaining serum levels within target therapeutic windows. Zero-order administration has been shown to reach an equilibrium with metabolic clearance, resulting in a constant serum concentration and bioavailability of released hormones. By exploiting surface-to-molecule interaction within nanochannel membranes, it is possible to achieve a long-term, constant diffusive release of agents from implantable reservoirs. In this study, we sought to demonstrate the controlled release of model hormones from a novel nanochannel system. We investigated the delivery of hormones through our nanochannel membrane over a period of 40 days. Levothyroxine, osteocalcin and testosterone were selected as representative hormones based on their different molecular properties and structures. The release mechanisms and transport behaviors of these hormones within 3, 5 and 40 nm channels were characterized. Results further supported the suitability of the nanochannels for sustained administration from implantable platforms.

  13. Redefining the essential trafficking pathway for outer membrane lipoproteins

    OpenAIRE

    Grabowicz, Marcin; Silhavy, Thomas J.

    2017-01-01

    In Gram-negative bacteria, most lipoproteins synthesized in the inner membrane (IM) are trafficked to the outer membrane (OM). The Lol pathway is the trafficking paradigm: LolCDE releases lipoproteins from the IM; LolA shuttles them between membranes to LolB in the OM. Several OM lipoproteins are essential for viability. In apparent concordance, the Lol proteins are each essential in wild-type cells. However, we show that Escherichia coli grows well without LolA and LolB in the absence of one...

  14. Molecular machines open cell membranes.

    Science.gov (United States)

    García-López, Víctor; Chen, Fang; Nilewski, Lizanne G; Duret, Guillaume; Aliyan, Amir; Kolomeisky, Anatoly B; Robinson, Jacob T; Wang, Gufeng; Pal, Robert; Tour, James M

    2017-08-30

    Beyond the more common chemical delivery strategies, several physical techniques are used to open the lipid bilayers of cellular membranes. These include using electric and magnetic fields, temperature, ultrasound or light to introduce compounds into cells, to release molecular species from cells or to selectively induce programmed cell death (apoptosis) or uncontrolled cell death (necrosis). More recently, molecular motors and switches that can change their conformation in a controlled manner in response to external stimuli have been used to produce mechanical actions on tissue for biomedical applications. Here we show that molecular machines can drill through cellular bilayers using their molecular-scale actuation, specifically nanomechanical action. Upon physical adsorption of the molecular motors onto lipid bilayers and subsequent activation of the motors using ultraviolet light, holes are drilled in the cell membranes. We designed molecular motors and complementary experimental protocols that use nanomechanical action to induce the diffusion of chemical species out of synthetic vesicles, to enhance the diffusion of traceable molecular machines into and within live cells, to induce necrosis and to introduce chemical species into live cells. We also show that, by using molecular machines that bear short peptide addends, nanomechanical action can selectively target specific cell-surface recognition sites. Beyond the in vitro applications demonstrated here, we expect that molecular machines could also be used in vivo, especially as their design progresses to allow two-photon, near-infrared and radio-frequency activation.

  15. Molecular machines open cell membranes

    Science.gov (United States)

    García-López, Víctor; Chen, Fang; Nilewski, Lizanne G.; Duret, Guillaume; Aliyan, Amir; Kolomeisky, Anatoly B.; Robinson, Jacob T.; Wang, Gufeng; Pal, Robert; Tour, James M.

    2017-08-01

    Beyond the more common chemical delivery strategies, several physical techniques are used to open the lipid bilayers of cellular membranes. These include using electric and magnetic fields, temperature, ultrasound or light to introduce compounds into cells, to release molecular species from cells or to selectively induce programmed cell death (apoptosis) or uncontrolled cell death (necrosis). More recently, molecular motors and switches that can change their conformation in a controlled manner in response to external stimuli have been used to produce mechanical actions on tissue for biomedical applications. Here we show that molecular machines can drill through cellular bilayers using their molecular-scale actuation, specifically nanomechanical action. Upon physical adsorption of the molecular motors onto lipid bilayers and subsequent activation of the motors using ultraviolet light, holes are drilled in the cell membranes. We designed molecular motors and complementary experimental protocols that use nanomechanical action to induce the diffusion of chemical species out of synthetic vesicles, to enhance the diffusion of traceable molecular machines into and within live cells, to induce necrosis and to introduce chemical species into live cells. We also show that, by using molecular machines that bear short peptide addends, nanomechanical action can selectively target specific cell-surface recognition sites. Beyond the in vitro applications demonstrated here, we expect that molecular machines could also be used in vivo, especially as their design progresses to allow two-photon, near-infrared and radio-frequency activation.

  16. Membrane fusion and exocytosis.

    Science.gov (United States)

    Jahn, R; Südhof, T C

    1999-01-01

    Membrane fusion involves the merger of two phospholipid bilayers in an aqueous environment. In artificial lipid bilayers, fusion proceeds by means of defined transition states, including hourglass-shaped intermediates in which the proximal leaflets of the fusing membranes are merged whereas the distal leaflets are separate (fusion stalk), followed by the reversible opening of small aqueous fusion pores. Fusion of biological membranes requires the action of specific fusion proteins. Best understood are the viral fusion proteins that are responsible for merging the viral with the host cell membrane during infection. These proteins undergo spontaneous and dramatic conformational changes upon activation. In the case of the paradigmatic fusion proteins of the influenza virus and of the human immunodeficiency virus, an amphiphilic fusion peptide is inserted into the target membrane. The protein then reorients itself, thus forcing the fusing membranes together and inducing lipid mixing. Fusion of intracellular membranes in eukaryotic cells involves several protein families including SNAREs, Rab proteins, and Sec1/Munc-18 related proteins (SM-proteins). SNAREs form a novel superfamily of small and mostly membrane-anchored proteins that share a common motif of about 60 amino acids (SNARE motif). SNAREs reversibly assemble into tightly packed helical bundles, the core complexes. Assembly is thought to pull the fusing membranes closely together, thus inducing fusion. SM-proteins comprise a family of soluble proteins that bind to certain types of SNAREs and prevent the formation of core complexes. Rab proteins are GTPases that undergo highly regulated GTP-GDP cycles. In their GTP form, they interact with specific proteins, the effector proteins. Recent evidence suggests that Rab proteins function in the initial membrane contact connecting the fusing membranes but are not involved in the fusion reaction itself.

  17. Imaging height fluctuations in free-standing graphene membranes

    Science.gov (United States)

    Dorsey, Kyle; Miskin, Marc; Barnard, Arthur; Rose, Peter; Cohen, Itai; McEuen, Paul

    We present a technique based on multi-wavelength interference microscopy to measure the heights of observed ripples in free-standing graphene membranes. Graphene membranes released from a transparent substrate produce interference fringes when viewed in the reflection mode of an inverted microscope(Blees et. al. Nature 524 (7564): 204-207 (2015)). The fringes correspond to corrugation of the membrane as it floats near an interface. A single set of fringes is insufficient to uniquely determine the height profile, as a given fringe spacing can correspond to an increase or decrease in height by λ / 2 . Imaging at multiple wavelengths resolves the ambiguities in phase, and enables unique determination of the height profile of the membrane (Schilling et. al.Phys. Rev. E, 69:021901, 2004). We utilize this technique to map out the height fluctuations in free-standing graphene membranes to answer questions about fundamental mechanical properties of two-dimensional materials.

  18. Interaction of multiple biomimetic antimicrobial polymers with model bacterial membranes

    Energy Technology Data Exchange (ETDEWEB)

    Baul, Upayan, E-mail: upayanb@imsc.res.in; Vemparala, Satyavani, E-mail: vani@imsc.res.in [The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai 600113 (India); Kuroda, Kenichi, E-mail: kkuroda@umich.edu [Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan 48109 (United States)

    2014-08-28

    Using atomistic molecular dynamics simulations, interaction of multiple synthetic random copolymers based on methacrylates on prototypical bacterial membranes is investigated. The simulations show that the cationic polymers form a micellar aggregate in water phase and the aggregate, when interacting with the bacterial membrane, induces clustering of oppositely charged anionic lipid molecules to form clusters and enhances ordering of lipid chains. The model bacterial membrane, consequently, develops lateral inhomogeneity in membrane thickness profile compared to polymer-free system. The individual polymers in the aggregate are released into the bacterial membrane in a phased manner and the simulations suggest that the most probable location of the partitioned polymers is near the 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) clusters. The partitioned polymers preferentially adopt facially amphiphilic conformations at lipid-water interface, despite lacking intrinsic secondary structures such as α-helix or β-sheet found in naturally occurring antimicrobial peptides.

  19. The Multifaceted Role of SNARE Proteins in Membrane Fusion.

    Science.gov (United States)

    Han, Jing; Pluhackova, Kristyna; Böckmann, Rainer A

    2017-01-01

    Membrane fusion is a key process in all living organisms that contributes to a variety of biological processes including viral infection, cell fertilization, as well as intracellular transport, and neurotransmitter release. In particular, the various membrane-enclosed compartments in eukaryotic cells need to exchange their contents and communicate across membranes. Efficient and controllable fusion of biological membranes is known to be driven by cooperative action of SNARE proteins, which constitute the central components of the eukaryotic fusion machinery responsible for fusion of synaptic vesicles with the plasma membrane. During exocytosis, vesicle-associated v-SNARE (synaptobrevin) and target cell-associated t-SNAREs (syntaxin and SNAP-25) assemble into a core trans-SNARE complex. This complex plays a versatile role at various stages of exocytosis ranging from the priming to fusion pore formation and expansion, finally resulting in the release or exchange of the vesicle content. This review summarizes current knowledge on the intricate molecular mechanisms underlying exocytosis triggered and catalyzed by SNARE proteins. Particular attention is given to the function of the peptidic SNARE membrane anchors and the role of SNARE-lipid interactions in fusion. Moreover, the regulatory mechanisms by synaptic auxiliary proteins in SNARE-driven membrane fusion are briefly outlined.

  20. Plasma membrane ATPases

    DEFF Research Database (Denmark)

    Palmgren, Michael Broberg; Bækgaard, Lone; Lopez Marques, Rosa Laura

    2011-01-01

    The plasma membrane separates the cellular contents from the surrounding environment. Nutrients must enter through the plasma membrane in order to reach the cell interior, and toxic metabolites and several ions leave the cell by traveling across the same barrier. Biological pumps in the plasma me...

  1. Polymide gas separation membranes

    Science.gov (United States)

    Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz

    2004-09-14

    Soluble polyamic acid salt (PAAS) precursors comprised of tertiary and quaternary amines, ammonium cations, sulfonium cations, or phosphonium cations, are prepared and fabricated into membranes that are subsequently imidized and converted into rigid-rod polyimide articles, such as membranes with desirable gas separation properties. A method of enhancing solubility of PAAS polymers in alcohols is also disclosed.

  2. Enantioseparation with liquid membranes

    NARCIS (Netherlands)

    Gössi, Angelo; Riedl, Wolfgang; Schuur, Boelo

    Chiral resolution of racemic products is a challenging and important task in the pharmaceutical, agrochemical, flavor, polymer and fragrances industries. One of the options for these challenging separations is to use liquid membranes. Although liquid membranes have been known for almost four decades

  3. Silicon nitride nanosieve membrane

    NARCIS (Netherlands)

    Tong, D.H.; Jansen, Henricus V.; Gadgil, V.J.; Bostan, C.G.; Berenschot, Johan W.; van Rijn, C.J.M.; Elwenspoek, Michael Curt

    2004-01-01

    An array of very uniform cylindrical nanopores with a pore diameter as small as 25 nm has been fabricated in an ultrathin micromachined silicon nitride membrane using focused ion beam (FIB) etching. The pore size of this nanosieve membrane was further reduced to below 10 nm by coating it with

  4. Membrane capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Wal, van der A.

    2010-01-01

    Membrane capacitive deionization (MCDI) is an ion-removal process based on applying an electrical potential difference across an aqueous solution which flows in between oppositely placed porous electrodes, in front of which ion-exchange membranes are positioned. Due to the applied potential, ions

  5. Photoresponsive nanostructured membranes

    KAUST Repository

    Madhavan, Poornima; Sutisna, Burhannudin; Sougrat, Rachid; Nunes, Suzana Pereira

    2016-01-01

    The perspective of adding stimuli-response to isoporous membranes stimulates the development of separation devices with pores, which would open or close under control of environment chemical composition, temperature or exposure to light. Changes in pH and temperature have been previously investigated. In this work, we demonstrate for the first time the preparation of photoresponsive isoporous membranes, applying self-assembly non-solvent induced phase separation to a new light responsive block copolymer. First, we optimized the membrane formation by using poly(styrene-b-anthracene methyl methacrylate-b-methylmethacrylate) (PS-b-PAnMMA-b-PMMA) copolymer, identifying the most suitable solvent, copolymer block length, and other parameters. The obtained final triblock copolymer membrane morphologies were characterized using atomic force and electron microscopy. The microscopic analysis reveals that the PS-b-PAnMMA-b-PMMA copolymer can form both lamellar and ordered hexagonal nanoporous structures on the membrane top layer in appropriate solvent compositions. The nanostructured membrane emits fluorescence due to the presence of the anthracene mid-block. On irradiation of light the PS-b-PAnMMA-b-PMMA copolymer membranes has an additional stimuli response. The anthracene group undergoes conformational changes by forming [4 + 4] cycloadducts and this alters the membrane's water flux and solute retention. © 2016 The Royal Society of Chemistry.

  6. Novel membrane-based electrochemical sensor for real-time bio-applications

    DEFF Research Database (Denmark)

    Al Atraktchi, Fatima Al-Zahraa; Bakmand, Tanya; Dimaki, Maria

    2014-01-01

    This article presents a novel membrane-based sensor for real-time electrochemical investigations of cellular- or tissue cultures. The membrane sensor enables recording of electrical signals from a cell culture without any signal dilution, thus avoiding loss of sensitivity. Moreover, the porosity...... of the membrane provides optimal culturing conditions similar to existing culturing techniques allowing more efficient nutrient uptake and molecule release. The patterned sensor electrodes were fabricated on a porous membrane by electron-beam evaporation. The electrochemical performance of the membrane electrodes...

  7. Large-scale membrane transfer process: its application to single-crystal-silicon continuous membrane deformable mirror

    International Nuclear Information System (INIS)

    Wu, Tong; Sasaki, Takashi; Hane, Kazuhiro; Akiyama, Masayuki

    2013-01-01

    This paper describes a large-scale membrane transfer process developed for the construction of large-scale membrane devices via the transfer of continuous single-crystal-silicon membranes from one substrate to another. This technique is applied for fabricating a large stroke deformable mirror. A bimorph spring array is used to generate a large air gap between the mirror membrane and the electrode. A 1.9 mm × 1.9 mm × 2 µm single-crystal-silicon membrane is successfully transferred to the electrode substrate by Au–Si eutectic bonding and the subsequent all-dry release process. This process provides an effective approach for transferring a free-standing large continuous single-crystal-silicon to a flexible suspension spring array with a large air gap. (paper)

  8. Molecular Interactions at Membranes

    DEFF Research Database (Denmark)

    Jagalski, Vivien

    . Today, we know more than ever before about the properties of biological membranes. Advanced biophysical techniques and sophisticated membrane models allow us to answer specific questions about the structure of the components within membranes and their interactions. However, many detailed structural...... the surface-immobilization of LeuT by exchanging the detergent with natural phosphatidylcholine (PC) lipids. Various surface sensitive techniques, including neutron reflectometry (NR), are employed and finally enabled us to confirm the gross structure of LeuT in a lipid environment as predicted by molecular...... dynamic simulations. In a second study, the co-localization of three toxic plant-derived diterpene resin acids (RAs) within DPPC membranes was investigated. These compounds are reported to disrupt the membrane and increase its fluidity. The RAs used in this study vary in their toxicity while...

  9. Membrane technology and applications

    International Nuclear Information System (INIS)

    Khalil, F.H.

    1997-01-01

    The main purpose of this dissertation is to prepare and characterize some synthetic membranes obtained by radiation-induced graft copolymerization of and A Am unitary and binary system onto nylon-6 films. The optimum conditions at which the grafting process proceeded homogeneously were determined. Some selected properties of the prepared membranes were studied. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), x-ray diffraction (XRD), mechanical properties and U.V./vis, instruments and techniques were used to characterize the prepared membranes. The use of such membranes for the decontamination of radioactive waste and some heavy metal ions as water pollutants were investigated. These grafted membranes showed good cation exchange properties and may be of practical interest in waste water treatment whether this water was radioactive or not. 4 tabs., 68 figs., 146 refs

  10. Antibacterial effects of electrospun chitosan/poly(ethylene oxide) nanofibrous membranes loaded with chlorhexidine and silver

    NARCIS (Netherlands)

    Song, J.; Remmers, S.J.; Shao, J.; Kolwijck, E.; Walboomers, X.F.; Jansen, J.A.; Leeuwenburgh, S.C.; Yang, F.

    2016-01-01

    To prevent percutaneous device associated infections (PDAIs), we prepared electrospun chitosan/poly(ethylene oxide) (PEO) nanofibrous membrane containing silver nanoparticles as an implantable delivery vehicle for the dual release of chlorhexidine and silver ions. We observed that the silver

  11. Refillable and magnetically actuated drug delivery system using pear-shaped viscoelastic membrane

    KAUST Repository

    So, Hongyun; Seo, Young Ho; Pisano, Albert P.

    2014-01-01

    We report a refillable and valveless drug delivery device actuated by an external magnetic field for on-demand drug release to treat localized diseases. The device features a pear-shaped viscoelastic magnetic membrane inducing asymmetrical

  12. RAVEN Beta Release

    International Nuclear Information System (INIS)

    Rabiti, Cristian; Alfonsi, Andrea; Cogliati, Joshua Joseph; Mandelli, Diego; Kinoshita, Robert Arthur; Wang, Congjian; Maljovec, Daniel Patrick; Talbot, Paul William

    2016-01-01

    This documents the release of the Risk Analysis Virtual Environment (RAVEN) code. A description of the RAVEN code is provided, and discussion of the release process for the M2LW-16IN0704045 milestone. The RAVEN code is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is capable of investigating the system response as well as the input space using Monte Carlo, Grid, or Latin Hyper Cube sampling schemes, but its strength is focused toward system feature discovery, such as limit surfaces, separating regions of the input space leading to system failure, using dynamic supervised learning techniques. RAVEN has now increased in maturity enough for the Beta 1.0 release.

  13. RAVEN Beta Release

    Energy Technology Data Exchange (ETDEWEB)

    Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cogliati, Joshua Joseph [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinoshita, Robert Arthur [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Congjian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Maljovec, Daniel Patrick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talbot, Paul William [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-02-01

    This documents the release of the Risk Analysis Virtual Environment (RAVEN) code. A description of the RAVEN code is provided, and discussion of the release process for the M2LW-16IN0704045 milestone. The RAVEN code is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is capable of investigating the system response as well as the input space using Monte Carlo, Grid, or Latin Hyper Cube sampling schemes, but its strength is focused toward system feature discovery, such as limit surfaces, separating regions of the input space leading to system failure, using dynamic supervised learning techniques. RAVEN has now increased in maturity enough for the Beta 1.0 release.

  14. Microfabricated hydrogen sensitive membranes

    Energy Technology Data Exchange (ETDEWEB)

    Naddaf, A.; Kraetz, L. [Lehrstuhl fuer Thermische Verfahrenstechnik, Technische Universitaet Kaiserslautern (Germany); Detemple, P.; Schmitt, S.; Hessel, V. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany); Faqir, N. [University of Jordan, Amman (Jordan); Bart, H.J.

    2009-01-15

    Thin, defect-free palladium, palladium/copper and palladium/silver hydrogen absorbing membranes were microfabricated. A dual sputtering technique was used to deposit the palladium alloy membranes of only 1 {mu}m thickness on a nonporous silicon substrate. Advanced silicon etching (ASE) was applied on the backside to create a mechanically stable support structure for the thin films. Performance evaluation was carried out for different gases in a temperature range of 20 C to 298 C at a constant differential pressure of 110 kPa at the two sides of the membrane. The composite membranes show an excellent permeation rate of hydrogen, which appears to be 0.05 Pa m{sup 3} s{sup -1} and 0.01.10{sup -3} Pa m{sup 3} s{sup -1} at 20 C for the microfabricated 23 % silver and the 53 % copper composite membranes, respectively. The selectivity to hydrogen over a gas mixture containing, in addition to hydrogen, carbon monoxide, carbon dioxide and nitrogen was measured. The mass spectrometer did not detect any CO{sub 2} or CO, showing that the membrane is completely hydrogen selective. The microfabricated membranes exhibit both high mechanical strength (they easily withstand pressures up to 4 bar) and high thermal stability (up to 650 C). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  15. Catalytic nanoporous membranes

    Science.gov (United States)

    Pellin, Michael J; Hryn, John N; Elam, Jeffrey W

    2013-08-27

    A nanoporous catalytic membrane which displays several unique features Including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity. Also provided is a method for producing a catalytic membrane having flow-through pores and discreet catalytic clusters adhering to the inside surfaces of the pores.

  16. Computational modeling and analysis of iron release from macrophages.

    Directory of Open Access Journals (Sweden)

    Alka A Potdar

    2014-07-01

    Full Text Available A major process of iron homeostasis in whole-body iron metabolism is the release of iron from the macrophages of the reticuloendothelial system. Macrophages recognize and phagocytose senescent or damaged erythrocytes. Then, they process the heme iron, which is returned to the circulation for reutilization by red blood cell precursors during erythropoiesis. The amount of iron released, compared to the amount shunted for storage as ferritin, is greater during iron deficiency. A currently accepted model of iron release assumes a passive-gradient with free diffusion of intracellular labile iron (Fe2+ through ferroportin (FPN, the transporter on the plasma membrane. Outside the cell, a multi-copper ferroxidase, ceruloplasmin (Cp, oxidizes ferrous to ferric ion. Apo-transferrin (Tf, the primary carrier of soluble iron in the plasma, binds ferric ion to form mono-ferric and di-ferric transferrin. According to the passive-gradient model, the removal of ferrous ion from the site of release sustains the gradient that maintains the iron release. Subcellular localization of FPN, however, indicates that the role of FPN may be more complex. By experiments and mathematical modeling, we have investigated the detailed mechanism of iron release from macrophages focusing on the roles of the Cp, FPN and apo-Tf. The passive-gradient model is quantitatively analyzed using a mathematical model for the first time. A comparison of experimental data with model simulations shows that the passive-gradient model cannot explain macrophage iron release. However, a facilitated-transport model associated with FPN can explain the iron release mechanism. According to the facilitated-transport model, intracellular FPN carries labile iron to the macrophage membrane. Extracellular Cp accelerates the oxidation of ferrous ion bound to FPN. Apo-Tf in the extracellular environment binds to the oxidized ferrous ion, completing the release process. Facilitated-transport model can

  17. Rotating bubble membrane radiator

    Science.gov (United States)

    Webb, Brent J.; Coomes, Edmund P.

    1988-12-06

    A heat radiator useful for expelling waste heat from a power generating system aboard a space vehicle is disclosed. Liquid to be cooled is passed to the interior of a rotating bubble membrane radiator, where it is sprayed into the interior of the bubble. Liquid impacting upon the interior surface of the bubble is cooled and the heat radiated from the outer surface of the membrane. Cooled liquid is collected by the action of centrifical force about the equator of the rotating membrane and returned to the power system. Details regarding a complete space power system employing the radiator are given.

  18. Thermo-and pH-sensitive hydrogel membranes composed of poly(N-isopropylacrylamide)-hyaluronan for biomedical applications: Influence of hyaluronan incorporation on the membrane properties.

    Science.gov (United States)

    Kamoun, Elbadawy A; Fahmy, Alaa; Taha, Tarek H; El-Fakharany, Esmail M; Makram, Mohamed; Soliman, Hesham M A; Shehata, Hassan

    2018-01-01

    Interpenetrating hydrogel membranes consisting of pH-sensitive hyaluronan (HA) and thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAM) were synthesized using redox polymerization, followed by N,N-methylenebisacrylamide (BIS) and epichlorohydrin (EPI) were added as chemical crosslinkers. The interaction between membrane compositions has been characterized by FTIR spectroscopy and discussed intensively. The result indicates that HA incorporation in membranes increase the gel fraction, swelling uptake, and the flexibility/elasticity of crosslinked membranes, however it reduced oppositely the mechanical elongation of membranes. PNIPAAm-HA hydrogels responded to both temperature and pH changes and the stimuli-responsiveness was reversible. However, in vitro bioevaluation results revealed that the released ampicillin during the burst release time was sharply influenced and increased with increasing HA contents in membranes; afterwards it became sustainable. Whereas, high HA contents in hydrogels unexpectedly impacted negatively on the cells viability, owing to the viscosity of cell culture media changed. A big resistance was observed against microbial growth of Staphylococcus aureus, Salmonella typhi, and Candida albicans in case of pure PNIPAAm hydrogel membranes without HA or ampicillin. However, HA incorporation or the loaded ampicillin in membranes showed unexpected easily microbial growth. The fast release performance with dual pH-thermo-sensitive hydrogels were suggested as promising materials for quick drug carrier in the biomedical field. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Hydraulic release oil tool

    International Nuclear Information System (INIS)

    Mims, M.G.; Mueller, M.D.; Ehlinger, J.C.

    1992-01-01

    This patent describes a hydraulic release tool. It comprises a setting assembly; a coupling member for coupling to drill string or petroleum production components, the coupling member being a plurality of sockets for receiving the dogs in the extended position and attaching the coupling member the setting assembly; whereby the setting assembly couples to the coupling member by engagement of the dogs in the sockets of releases from and disengages the coupling member in movement of the piston from its setting to its reposition in response to a pressure in the body in exceeding the predetermined pressure; and a relief port from outside the body into its bore and means to prevent communication between the relief port and the bore of the body axially of the piston when the piston is in the setting position and to establish such communication upon movement of the piston from the setting position to the release position and reduce the pressure in the body bore axially of the piston, whereby the reduction of the pressure signals that the tool has released the coupling member

  20. APASS Data Release 10

    Science.gov (United States)

    Henden, Arne A.; Levine, Stephen; Terrell, Dirk; Welch, Douglas L.; Munari, Ulisse; Kloppenborg, Brian K.

    2018-06-01

    The AAVSO Photometric All-Sky Survey (APASS) has been underway since 2010. This survey covers the entire sky from 7.5 knowledge of the optical train distortions. With these changes, DR10 includes many more stars than prior releases. We describe the survey, its remaining limitations, and prospects for the future, including a very-bright-star extension.

  1. Release the Prisoners Game

    Science.gov (United States)

    Van Hecke, Tanja

    2011-01-01

    This article presents the mathematical approach of the optimal strategy to win the "Release the prisoners" game and the integration of this analysis in a math class. Outline lesson plans at three different levels are given, where simulations are suggested as well as theoretical findings about the probability distribution function and its mean…

  2. Growth hormone (GH)-releasing activity of chicken GH-releasing hormone (GHRH) in chickens.

    Science.gov (United States)

    Harvey, S; Gineste, C; Gaylinn, B D

    2014-08-01

    Two peptides with sequence similarities to growth hormone releasing hormone (GHRH) have been identified by analysis of the chicken genome. One of these peptides, chicken (c) GHRH-LP (like peptide) was previously found to poorly bind to chicken pituitary membranes or to cloned and expressed chicken GHRH receptors and had little, if any, growth hormone (GH)-releasing activity in vivo or in vitro. In contrast, a second more recently discovered peptide, cGHRH, does bind to cloned and expressed cGHRH receptors and increases cAMP activity in transfected cells. The possibility that this peptide may have in vivo GH-releasing activity was therefore assessed. The intravenous (i.v.) administration of cGHRH to immature chickens, at doses of 3-100 μg/kg, significantly increased circulating GH concentrations within 10 min of injection and the plasma GH levels remained elevated for at least 30 min after the injection of maximally effective doses. The plasma GH responses to cGHRH were comparable with those induced by human (h) or porcine (p) GHRH preparations and to that induced by thyrotropin releasing hormone (TRH). In marked contrast, the i.v. injection of cGHRH-LP had no significant effect on circulating GH concentrations in immature chicks. GH release was also increased from slaughterhouse chicken pituitary glands perifused for 5 min with cGHRH at doses of 0.1 μg/ml or 1.0 μg/ml, comparable with GH responses to hGHRH1-44. In contrast, the perifusion of chicken pituitary glands with cGHRH-LP had no significant effect on GH release. In summary, these results demonstrate that cGHRH has GH-releasing activity in chickens and support the possibility that it is the endogenous ligand of the cGHRH receptor. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Membrane Assisted Enzyme Fractionation

    DEFF Research Database (Denmark)

    Yuan, Linfeng

    to the variation in size of the proteins and a reasonable separation factor can be observed only when the size difference is in the order of 10 or more. This is partly caused by concentration polarization and membrane fouling which hinders an effective separation of the proteins. Application of an electric field...... across the porous membrane has been demonstrated to be an effective way to reduce concentration polarization and membrane fouling. In addition, this technique can also be used to separate the proteins based on difference in charge, which to some extent overcome the limitations of size difference...... of proteins on the basis of their charge, degree of hydrophobicity, affinity or size. Adequate purity is often not achieved unless several purification steps are combined thereby increasing cost and reducing product yield. Conventional fractionation of proteins using ultrafiltration membranes is limited...

  4. Fuel cell membrane humidification

    Science.gov (United States)

    Wilson, Mahlon S.

    1999-01-01

    A polymer electrolyte membrane fuel cell assembly has an anode side and a cathode side separated by the membrane and generating electrical current by electrochemical reactions between a fuel gas and an oxidant. The anode side comprises a hydrophobic gas diffusion backing contacting one side of the membrane and having hydrophilic areas therein for providing liquid water directly to the one side of the membrane through the hydrophilic areas of the gas diffusion backing. In a preferred embodiment, the hydrophilic areas of the gas diffusion backing are formed by sewing a hydrophilic thread through the backing. Liquid water is distributed over the gas diffusion backing in distribution channels that are separate from the fuel distribution channels.

  5. Wrinkles in reinforced membranes

    Science.gov (United States)

    Takei, Atsushi; Brau, Fabian; Roman, Benoît; Bico, José.

    2012-02-01

    We study, through model experiments, the buckling under tension of an elastic membrane reinforced with a more rigid strip or a fiber. In these systems, the compression of the rigid layer is induced through Poisson contraction as the membrane is stretched perpendicularly to the strip. Although strips always lead to out-of-plane wrinkles, we observe a transition from out-of-plane to in plane wrinkles beyond a critical strain in the case of fibers embedded into the elastic membranes. The same transition is also found when the membrane is reinforced with a wall of the same material depending on the aspect ratio of the wall. We describe through scaling laws the evolution of the morphology of the wrinkles and the different transitions as a function of material properties and stretching strain.

  6. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-02-01

    This factsheet describes a research project that will focus on the development and application of nonporous high gas flux perfluoro membranes with high temperature rating and excellent chemical resistance.

  7. Influence of Erythrocyte Membrane Stability in Atherosclerosis.

    Science.gov (United States)

    da Silva Garrote-Filho, Mario; Bernardino-Neto, Morun; Penha-Silva, Nilson

    2017-04-01

    The purpose of this study is to show how an excess of cholesterol in the erythrocyte membrane contributes stochastically to the progression of atherosclerosis, leading to damage in blood rheology and O 2 transport, deposition of cholesterol (from trapped erythrocytes) in an area of intraplaque hemorrhage, and local exacerbation of oxidative stress. Cholesterol contained in the membrane of erythrocytes trapped in an intraplaque hemorrhage contributes to the growth of the necrotic nucleus. There is even a relationship between the amount of cholesterol in the erythrocyte membrane and the severity of atherosclerosis. In addition, the volume variability among erythrocytes, measured by RDW, is predictive of a worsening of this disease. Erythrocytes contribute to the development of atherosclerosis in several ways, especially when trapped in intraplate hemorrhage. These erythrocytes are oxidized and phagocytosed by macrophages. The cholesterol present in the membrane of these erythrocytes subsequently contributes to the growth of the atheroma plaque. In addition, when they rupture, erythrocytes release hemoglobin, which leads to the generation of free radicals. Finally, increased RDW may predict the worsening of atherosclerosis, due to the effects of inflammation and oxidative stress on erythropoiesis and erythrocyte volume. A better understanding of erythrocyte participation in atherosclerosis may contribute to the improvement of the prevention and treatment strategies of this disease.

  8. Membrane emulsification to produce perfume microcapsules

    Science.gov (United States)

    Pan, Xuemiao

    Microencapsulation is an efficient technology to deliver perfume oils from consumer products onto the surface of fabrics. Microcapsules having uniform size/mechanical strength, may provide better release performance. Membrane emulsification in a dispersion cell followed by in-situ polymerization was used to prepare narrow size distribution melamine-formaldehyde (MF) microcapsules containing several types of oil-based fragrances or ingredients. Investigated in this study are the parameters impacting to the size and size distribution of the droplets and final MF microcapsules. A pilot plant-scale cross-flow membrane system was also used to produce MF microcapsules, demonstrating that the membrane emulsification process has potential to be scaled up for industrial applications. In this study, health and environmental friendly poly (methyl methacrylate) (PMMA) microcapsules with narrow size distribution were also prepared for the first time using the dispersion cell membrane emulsification system. Characterization methods previously used for thin-shell microcapsules were expanded to analyse microcapsules with thick shells. The intrinsic mechanical properties of thick shells were determined using a micromanipulation technique and finite element analysis (FEM). The microcapsules structure was also considered in the determination of the permeability and diffusivity of the perfume oils in good solvents..

  9. Fabricating PFPE Membranes for Capillary Electrophoresis

    Science.gov (United States)

    Lee, Michael C.; Willis, Peter A.; Greer, Frank; Rolland, Jason

    2009-01-01

    A process has been developed for fabricating perfluoropolyether (PFPE) membranes that contain microscopic holes of precise sizes at precise locations. The membranes are to be incorporated into laboratory-on-a-chip microfluidic devices to be used in performing capillary electrophoresis. The present process is a modified version of part of the process, described in the immediately preceding article, that includes a step in which a liquid PFPE layer is cured into solid (membrane) form by use of ultraviolet light. In the present process, one exploits the fact that by masking some locations to prevent exposure to ultraviolet light, one can prevent curing of the PFPE in those locations. The uncured PFPE can be washed away from those locations in the subsequent release and cleaning steps. Thus, holes are formed in the membrane in those locations. The most straightforward way to implement the modification is to use, during the ultraviolet-curing step, an ultraviolet photomask similar to the photomasks used in fabricating microelectronic devices. In lieu of such a photomask, one could use a mask made of any patternable ultraviolet-absorbing material (for example, an ink or a photoresist).

  10. Temperature responsive track membranes

    International Nuclear Information System (INIS)

    Omichi, H.; Yoshido, M.; Asano, M.; Tamada, H.

    1994-01-01

    A new track membrane was synthesized by introducing polymeric hydrogel to films. Such a monomer as amino acid group containing acryloyl or methacryloyl was either co-polymerized with diethylene glycol-bis-ally carbonate followed by on beam irradiation and chemical etching, or graft co-polymerized onto a particle track membrane of CR-39. The pore size was controlled in water by changing the water temperature. Some films other than CR-39 were also examined. (author). 11 refs, 7 figs

  11. Dynamics of shear-induced ATP release from red blood cells.

    Science.gov (United States)

    Wan, Jiandi; Ristenpart, William D; Stone, Howard A

    2008-10-28

    Adenosine triphosphate (ATP) is a regulatory molecule for many cell functions, both for intracellular and, perhaps less well known, extracellular functions. An important example of the latter involves red blood cells (RBCs), which help regulate blood pressure by releasing ATP as a vasodilatory signaling molecule in response to the increased shear stress inside arterial constrictions. Although shear-induced ATP release has been observed widely and is believed to be triggered by deformation of the cell membrane, the underlying mechanosensing mechanism inside RBCs is still controversial. Here, we use an in vitro microfluidic approach to investigate the dynamics of shear-induced ATP release from human RBCs with millisecond resolution. We demonstrate that there is a sizable delay time between the onset of increased shear stress and the release of ATP. This response time decreases with shear stress, but surprisingly does not depend significantly on membrane rigidity. Furthermore, we show that even though the RBCs deform significantly in short constrictions (duration of increased stress <3 ms), no measurable ATP is released. This critical timescale is commensurate with a characteristic membrane relaxation time determined from observations of the cell deformation by using high-speed video. Taken together our results suggest a model wherein the retraction of the spectrin-actin cytoskeleton network triggers the mechanosensitive ATP release and a shear-dependent membrane viscosity controls the rate of release.

  12. Plasma membrane damage detected by nucleic acid leakage

    International Nuclear Information System (INIS)

    Fortunati, E.; Bianchi, V.

    1989-01-01

    Among the indicators of membrane damage, the leakage of intracellular components into the medium is the most directly related to the perturbations of the membrane molecular organization. The extent of the damage can be evaluated from the size of the released components. We have designed a protocol for the detection of membrane leakage based on the preincubation of cells with tritiated adenine for 24 h, followed by a 24-h chase in nonradioactive medium. The treatment takes place when the distribution of the precursor among its end products has reached the plateau, and thus the differences of radioactivity in the fractions obtained from the control and treated cultures (medium, nucleotide pool, RNA, DNA) correspond to actual quantitative variations induced by the test chemical. Aliquots of the medium are processed to determine which percentage of the released material is macromolecular, in order to distinguish between mild and severe membrane damage. The origin of the extracellular radioactivity can be recognized from the variations of RNA counts in the treated cells. DNA radioactivity is used to evaluate the number of cells that remain attached to the plates in the different conditions of treatment. By this means, generalized permeabilization of membranes to macromolecules is distinguished from complete solubilization of only a subpopulation of cells. We present some examples of application of the protocol with detergents (LAS, SDS, Triton X-100) and with Cr(VI), which damages cell membranes by a different mechanism of action

  13. Inverse colloidal crystal membranes for hydrophobic interaction membrane chromatography.

    Science.gov (United States)

    Vu, Anh T; Wang, Xinying; Wickramasinghe, S Ranil; Yu, Bing; Yuan, Hua; Cong, Hailin; Luo, Yongli; Tang, Jianguo

    2015-08-01

    Hydrophobic interaction membrane chromatography has gained interest due to its excellent performance in the purification of humanized monoclonal antibodies. The membrane material used in hydrophobic interaction membrane chromatography has typically been commercially available polyvinylidene fluoride. In this contribution, newly developed inverse colloidal crystal membranes that have uniform pores, high porosity and, therefore, high surface area for protein binding are used as hydrophobic interaction membrane chromatography membranes for humanized monoclonal antibody immunoglobulin G purification. The capacity of the inverse colloidal crystal membranes developed here is up to ten times greater than commercially available polyvinylidene fluoride membranes with a similar pore size. This work highlights the importance of developing uniform pore size high porosity membranes in order to maximize the capacity of hydrophobic interaction membrane chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Fabrication of electrospun nanofibrous membranes for membrane distillation application

    KAUST Repository

    Francis, Lijo

    2013-02-01

    Nanofibrous membranes of Matrimid have been successfully fabricated using an electrospinning technique under optimized conditions. Nanofibrous membranes are found to be highly hydrophobic with a high water contact angle of 130°. Field emission scanning electron microscopy and pore size distribution analysis revealed the big pore size structure of electrospun membranes to be greater than 2 μm and the pore size distribution is found to be narrow. Flat sheet Matrimid membranes were fabricated via casting followed by phase inversion. The morphology, pore size distribution, and water contact angle were measured and compared with the electrospun membranes. Both membranes fabricated by electrospinning and phase inversion techniques were tested in a direct contact membrane distillation process. Electrospun membranes showed high water vapor flux of 56 kg/m2-h, which is very high compared to the casted membrane as well as most of the fabricated and commercially available highly hydrophobic membranes. ©2013 Desalination Publications.

  15. Far Western: probing membranes.

    Science.gov (United States)

    Einarson, Margret B; Pugacheva, Elena N; Orlinick, Jason R

    2007-08-01

    INTRODUCTIONThe far-Western technique described in this protocol is fundamentally similar to Western blotting. In Western blots, an antibody is used to detect a query protein on a membrane. In contrast, in a far-Western blot (also known as an overlay assay) the antibody is replaced by a recombinant GST fusion protein (produced and purified from bacteria), and the assay detects the interaction of this protein with target proteins on a membrane. The membranes are washed and blocked, incubated with probe protein, washed again, and subjected to autoradiography. The GST fusion (probe) proteins are often labeled with (32)P; alternatively, the membrane can be probed with unlabeled GST fusion protein, followed by detection using commercially available GST antibodies. The nonradioactive approach is substantially more expensive (due to the purchase of antibody and detection reagents) than using radioactively labeled proteins. In addition, care must be taken to control for nonspecific interactions with GST alone and a signal resulting from antibody cross-reactivity. In some instances, proteins on the membrane are not able to interact after transfer. This may be due to improper folding, particularly in the case of proteins expressed from a phage expression library. This protocol describes a way to overcome this by washing the membrane in denaturation buffer, which is then serially diluted to permit slow renaturation of the proteins.

  16. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  17. Bacterial membrane proteomics.

    Science.gov (United States)

    Poetsch, Ansgar; Wolters, Dirk

    2008-10-01

    About one quarter to one third of all bacterial genes encode proteins of the inner or outer bacterial membrane. These proteins perform essential physiological functions, such as the import or export of metabolites, the homeostasis of metal ions, the extrusion of toxic substances or antibiotics, and the generation or conversion of energy. The last years have witnessed completion of a plethora of whole-genome sequences of bacteria important for biotechnology or medicine, which is the foundation for proteome and other functional genome analyses. In this review, we discuss the challenges in membrane proteome analysis, starting from sample preparation and leading to MS-data analysis and quantification. The current state of available proteomics technologies as well as their advantages and disadvantages will be described with a focus on shotgun proteomics. Then, we will briefly introduce the most abundant proteins and protein families present in bacterial membranes before bacterial membrane proteomics studies of the last years will be presented. It will be shown how these works enlarged our knowledge about the physiological adaptations that take place in bacteria during fine chemical production, bioremediation, protein overexpression, and during infections. Furthermore, several examples from literature demonstrate the suitability of membrane proteomics for the identification of antigens and different pathogenic strains, as well as the elucidation of membrane protein structure and function.

  18. Biomimetic membranes and methods of making biomimetic membranes

    Science.gov (United States)

    Rempe, Susan; Brinker, Jeffrey C.; Rogers, David Michael; Jiang, Ying-Bing; Yang, Shaorong

    2016-11-08

    The present disclosure is directed to biomimetic membranes and methods of manufacturing such membranes that include structural features that mimic the structures of cellular membrane channels and produce membrane designs capable of high selectivity and high permeability or adsorptivity. The membrane structure, material and chemistry can be selected to perform liquid separations, gas separation and capture, ion transport and adsorption for a variety of applications.

  19. Polyurethane Nanofiber Membranes for Waste Water Treatment by Membrane Distillation

    OpenAIRE

    Jiříček, T.; Komárek, M.; Lederer, T.

    2017-01-01

    Self-sustained electrospun polyurethane nanofiber membranes were manufactured and tested on a direct-contact membrane distillation unit in an effort to find the optimum membrane thickness to maximize flux rate and minimize heat losses across the membrane. Also salt retention and flux at high salinities up to 100 g kg−1 were evaluated. Even though the complex structure of nanofiber layers has extreme specific surface and porosity, membrane performance was surprisingly predictable; the highest ...

  20. Liberated PKA Catalytic Subunits Associate with the Membrane via Myristoylation to Preferentially Phosphorylate Membrane Substrates.

    Science.gov (United States)

    Tillo, Shane E; Xiong, Wei-Hong; Takahashi, Maho; Miao, Sheng; Andrade, Adriana L; Fortin, Dale A; Yang, Guang; Qin, Maozhen; Smoody, Barbara F; Stork, Philip J S; Zhong, Haining

    2017-04-18

    Protein kinase A (PKA) has diverse functions in neurons. At rest, the subcellular localization of PKA is controlled by A-kinase anchoring proteins (AKAPs). However, the dynamics of PKA upon activation remain poorly understood. Here, we report that elevation of cyclic AMP (cAMP) in neuronal dendrites causes a significant percentage of the PKA catalytic subunit (PKA-C) molecules to be released from the regulatory subunit (PKA-R). Liberated PKA-C becomes associated with the membrane via N-terminal myristoylation. This membrane association does not require the interaction between PKA-R and AKAPs. It slows the mobility of PKA-C and enriches kinase activity on the membrane. Membrane-residing PKA substrates are preferentially phosphorylated compared to cytosolic substrates. Finally, the myristoylation of PKA-C is critical for normal synaptic function and plasticity. We propose that activation-dependent association of PKA-C renders the membrane a unique PKA-signaling compartment. Constrained mobility of PKA-C may synergize with AKAP anchoring to determine specific PKA function in neurons. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  1. Decontamination for free release

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, K A; Elder, G R [Bradtec Ltd., Bristol (United Kingdom)

    1997-02-01

    Many countries are seeking to treat radioactive waste in ways which meet the local regulatory requirements, but yet are cost effective when all contributing factors are assessed. In some countries there are increasing amounts of waste, arising from nuclear plant decommissioning, which are categorized as low level waste: however with suitable treatment a large part of such wastes might become beyond regulatory control and be able to be released as non-radioactive. The benefits and disadvantages of additional treatment before disposal need to be considered. Several processes falling within the overall description of decontamination for free release have been developed and applied, and these are outlined. In one instance the process seeks to take advantage of techniques and equipment used for decontaminating water reactor circuits intermittently through reactor life. (author). 9 refs, 1 fig., 3 tabs.

  2. Atmospheric Release Advisory Capability

    International Nuclear Information System (INIS)

    Dickerson, M.H.; Gudiksen, P.H.; Sullivan, T.J.

    1983-02-01

    The Atmospheric Release Advisory Capability (ARAC) project is a Department of Energy (DOE) sponsored real-time emergency response service available for use by both federal and state agencies in case of a potential or actual atmospheric release of nuclear material. The project, initiated in 1972, is currently evolving from the research and development phase to full operation. Plans are underway to expand the existing capability to continuous operation by 1984 and to establish a National ARAC Center (NARAC) by 1988. This report describes the ARAC system, its utilization during the past two years, and plans for its expansion during the next five to six years. An integral part of this expansion is due to a very important and crucial effort sponsored by the Defense Nuclear Agency to extend the ARAC service to approximately 45 Department of Defense (DOD) sites throughout the continental US over the next three years

  3. Border cell release

    DEFF Research Database (Denmark)

    Mravec, Jozef

    2017-01-01

    Plant border cells are specialised cells derived from the root cap with roles in the biomechanics of root growth and in forming a barrier against pathogens. The mechanism of highly localised cell separation which is essential for their release to the environment is little understood. Here I present...... in situ analysis of Brachypodium distachyon, a model organism for grasses which possess type II primary cell walls poor in pectin content. Results suggest similarity in spatial dynamics of pectic homogalacturonan during dicot and monocot border cell release. Integration of observations from different...... species leads to the hypothesis that this process most likely does not involve degradation of cell wall material but rather employs unique cell wall structural and compositional means enabling both the rigidity of the root cap as well as detachability of given cells on its surface....

  4. Energy released in fission

    International Nuclear Information System (INIS)

    James, M.F.

    1969-05-01

    The effective energy released in and following the fission of U-235, Pu-239 and Pu-241 by thermal neutrons, and of U-238 by fission spectrum neutrons, is discussed. The recommended values are: U-235 ... 192.9 ± 0.5 MeV/fission; U-238 ... 193.9 ± 0.8 MeV/fission; Pu-239 ... 198.5 ± 0.8 MeV/fission; Pu-241 ... 200.3 ± 0.8 MeV/fission. These values include all contributions except from antineutrinos and very long-lived fission products. The detailed contributions are discussed, and inconsistencies in the experimental data are pointed out. In Appendix A, the contribution to the total useful energy release in a reactor from reactions other than fission are discussed briefly, and in Appendix B there is a discussion of the variations in effective energy from fission with incident neutron energy. (author)

  5. Slow-release fertilizer

    Science.gov (United States)

    Ming, Douglas W.; Golden, D. C.

    1992-10-01

    A synthetic apatite containing agronutrients and a method for making the apatite are disclosed. The apatite comprises crystalline calcium phosphate having agronutrients dispersed in the crystalline structure. The agronutrients can comprise potassium, magnesium, sulfur, iron, manganese, molybdenum, chlorine, boron, copper and zinc in amounts suited for plant growth. The apatite can optionally comprise a carbonate and/or silicon solubility control agent. The agronutrients are released slowly as the apatite dissolves.

  6. EIA new releases

    International Nuclear Information System (INIS)

    1994-12-01

    This report was prepared by the Energy Information Administration. It contains news releases on items of interest to the petroleum, coal, nuclear, electric and alternate fuels industries ranging from economic outlooks to environmental concerns. There is also a listing of reports by industry and an energy education resource listing containing sources for free or low-cost energy-related educational materials for educators and primary and secondary students

  7. Atmospheric release advisory capability

    International Nuclear Information System (INIS)

    Sullivan, T.J.

    1981-01-01

    The ARAC system (Atmospheric Release Advisory Capability) is described. The system is a collection of people, computers, computer models, topographic data and meteorological input data that together permits a calculation of, in a quasi-predictive sense, where effluent from an accident will migrate through the atmosphere, where it will be deposited on the ground, and what instantaneous and integrated dose an exposed individual would receive

  8. Slow-release fertilizer

    Science.gov (United States)

    Ming, Douglas W. (Inventor); Golden, Dadigamuwage C. (Inventor)

    1995-01-01

    A synthetic apatite containing agronutrients and a method for making the apatite are disclosed. The apatite comprises crystalline calcium phosphate having agronutrients dispersed in the crystalline structure. The agronutrients can comprise potassium, magnesium, sulfur, iron, manganese, molybdenum, chlorine, boron, copper and zinc in amounts suited for plant growth. The apatite can optionally comprise a carbonate and/or silicon solubility control agent. The agronutrients are released slowly as the apatite dissolves.

  9. Piezo1 regulates mechanotransductive release of ATP from human RBCs.

    Science.gov (United States)

    Cinar, Eyup; Zhou, Sitong; DeCourcey, James; Wang, Yixuan; Waugh, Richard E; Wan, Jiandi

    2015-09-22

    Piezo proteins (Piezo1 and Piezo2) are recently identified mechanically activated cation channels in eukaryotic cells and associated with physiological responses to touch, pressure, and stretch. In particular, human RBCs express Piezo1 on their membranes, and mutations of Piezo1 have been linked to hereditary xerocytosis. To date, however, physiological functions of Piezo1 on normal RBCs remain poorly understood. Here, we show that Piezo1 regulates mechanotransductive release of ATP from human RBCs by controlling the shear-induced calcium (Ca(2+)) influx. We find that, in human RBCs treated with Piezo1 inhibitors or having mutant Piezo1 channels, the amounts of shear-induced ATP release and Ca(2+) influx decrease significantly. Remarkably, a critical extracellular Ca(2+) concentration is required to trigger significant ATP release, but membrane-associated ATP pools in RBCs also contribute to the release of ATP. Our results show how Piezo1 channels are likely to function in normal RBCs and suggest a previously unidentified mechanotransductive pathway in ATP release. Thus, we anticipate that the study will impact broadly on the research of red cells, cellular mechanosensing, and clinical studies related to red cell disorders and vascular disease.

  10. Pyrethroid insecticides evoke neurotransmitter release from rabbit striatal slices

    International Nuclear Information System (INIS)

    Eells, J.T.; Dubocovich, M.L.

    1988-01-01

    The effects of the synthetic pyrethroid insecticide fenvalerate ([R,S]-alpha-cyano-3-phenoxybenzyl[R,S]-2-(4-chlorophenyl)-3- methylbutyrate) on neurotransmitter release in rabbit brain slices were investigated. Fenvalerate evoked a calcium-dependent release of [ 3 H]dopamine and [ 3 H]acetylcholine from rabbit striatal slices that was concentration-dependent and specific for the toxic stereoisomer of the insecticide. The release of [ 3 H]dopamine and [ 3 H]acetylcholine by fenvalerate was modulated by D2 dopamine receptor activation and antagonized completely by the sodium channel blocker, tetrodotoxin. These findings are consistent with an action of fenvalerate on the voltage-dependent sodium channels of the presynaptic membrane resulting in membrane depolarization, and the release of dopamine and acetylcholine by a calcium-dependent exocytotic process. In contrast to results obtained in striatal slices, fenvalerate did not elicit the release of [ 3 H]norepinephrine or [ 3 H]acetylcholine from rabbit hippocampal slices indicative of regional differences in sensitivity to type II pyrethroid actions

  11. Zinc release from Schaffer collaterals and its significance.

    Science.gov (United States)

    Takeda, Atsushi; Nakajima, Satoko; Fuke, Sayuri; Sakurada, Naomi; Minami, Akira; Oku, Naoto

    2006-02-15

    On the basis of the evidence that approximately 45% of Schaffer collateral boutons are zinc-positive, zinc release from Schaffer collaterals and its action were examined in hippocampal slices. When zinc release from Schaffer collaterals was examined using ZnAF-2, a membrane-impermeable zinc indicator, ZnAF-2 signal in the stratum radiatum of the CA1 was increased by tetanic stimuli at 100 Hz for 1s, suggesting that zinc is released from Schaffer collaterals in a calcium- and impulse-dependent manner. An in vivo microdialysis experiment indicated that the perfusion with 10 microM zinc significantly decreases extracellular glutamate concentration in the CA1. When tetanic stimuli at 100 Hz for 5s were delivered to the dentate granule cells, the increase in calcium signal in the stratum radiatum of the CA1, as well as in the stratum lucidum of the CA3, was attenuated by addition of 10 microM zinc, while enhanced by addition of 1mM CaEDTA, a membrane-impermeable zinc chelator. The increase in calcium signal in the CA1, in which Schaffer collateral synapses exist, during delivery of tetanic stimuli at 100 Hz for 1s to the Schaffer collateral-commissural pathway was also significantly enhanced by addition of 1mM CaEDTA. These results suggest that zinc released from Schaffer collaterals suppressively modulates presynaptic and postsynaptic calcium signaling in the CA1, followed by the suppression of glutamate release.

  12. Contact: Releasing the news

    Science.gov (United States)

    Pinotti, Roberto

    The problem of mass behavior after man's future contacts with other intelligences in the universe is not only a challenge for social scientists and political leaders all over the world, but also a cultural time bomb as well. In fact, since the impact of CETI (Contact with Extraterrestrial Intelligence) on human civilization, with its different cultures, might cause a serious socio-anthropological shock, a common and predetermined worldwide strategy is necessary in releasing the news after the contact, in order to keep possible manifestations of fear, panic and hysteria under control. An analysis of past studies in this field and of parallel historical situations as analogs suggests a definite "authority crisis" in the public as a direct consequence of an unexpected release of the news, involving a devastating "chain reaction" process (from both the psychological and sociological viewpoints) of anomie and maybe the collapse of today's society. The only way to prevent all this is to prepare the world's public opinion concerning contact before releasing the news, and to develop a long-term strategy through the combined efforts of scientists, political leaders, intelligence agencies and the mass media, in order to create the cultural conditions in which a confrontation with ETI won't affect mankind in a traumatic way. Definite roles and tasks in this multi-level model are suggested.

  13. Influence of cholesterol and ceramide VI on the structure of multilamellar lipid membranes at water exchange

    International Nuclear Information System (INIS)

    Ryabova, N. Yu.; Kiselev, M. A.; Balagurov, A. M.

    2010-01-01

    The structural changes in the multilamellar lipid membranes of dipalmitoylphosphatidylcholine (DPPC)/cholesterol and DPPC/ceramide VI binary systems during hydration and dehydration have been studied by neutron diffraction. The effect of cholesterol and ceramide on the kinetics of water exchange in DPPC membranes is characterized. Compared to pure DPPC, membranes of binary systems swell faster during hydration (with a characteristic time of ∼30 min). Both compounds, ceramide VI and cholesterol, similarly affect the hydration of DPPC membranes, increasing the repeat distance due to the bilayer growth. However, in contrast to cholesterol, ceramide significantly reduces the thickness of the membrane water layer. The introduction of cholesterol into a DPPC membrane slows down the change in the parameters of the bilayer internal structure during dehydration. In the DPPC/ceramide VI/cholesterol ternary system (with a molar cholesterol concentration of 40%), cholesterol is partially released from the lamellar membrane structure into the crystalline phase.

  14. The cholinergic ligand binding material of axonal membranes

    International Nuclear Information System (INIS)

    Mautner, H.G.; Coronado, R.; Jumblatt, J.E.

    1986-01-01

    Choline acetyltransferase and acetylcholinesterase, the enzymes responsible for the synthesis and hydrolysis of ACh, are present in nerve fibers. In crustacean peripheral nerves, release of ACh from cut nerve fibers has been demonstrated. Previously closed membrane vesicles have been prepared from lobster walking leg nerve plasma membrane and saturable binding of cholinergic agonsist and antagonists to such membranes have been demonstrated. This paper studies this axonal cholinergic binding material, and elucidates its functions. The binding of tritium-nicotine to lobster nerve plasma membranes was antagonized by a series of cholinergic ligands as well as by a series of local anesthetics. This preparation was capable of binding I 125-alpha-bungarotoxin, a ligand widely believed to be a specific label for nicotinic ACh receptor. The labelling of 50 K petide band with tritium-MBTA following disulfide reduction is illustrated

  15. Antibacterial Membrane with a Bone-Like Structure for Guided Bone Regeneration

    Directory of Open Access Journals (Sweden)

    YuYuan Zhang

    2015-01-01

    Full Text Available An antibacterial membrane with a bone-like structure was developed for guided bone regeneration (GBR by mineralising acellular bovine pericardium (ABP and loading it with the antibiotic minocycline. The bovine pericardium (BP membrane was processed using physical and chemical methods to remove the cellular components and obtain ABP membranes. Then, the ABP membranes were biomimetically mineralised using a calcium phosphate-loaded agarose hydrogel system aided by electrophoresis. Minocycline was adsorbed to the mineralised ABP membrane, and the release profile in vitro was studied. The membranes were characterised through scanning electron microscopy, diffuse reflectance-Fourier transform infrared spectroscopy, and X-ray diffraction. Results showed that the ABP membrane had an asymmetric structure with a layer of densely arranged and irregularly aligned collagen fibrils. Collagen fibrils were calcified with the formation of intrafibrillar and interfibrillar hydroxyapatites similar to the bone structure. Minocycline was incorporated into the mineralised collagen membrane and could be released in vitro. This process endowed the membrane with an antibacterial property. This novel composite membrane offers promising applications in bioactive GBR.

  16. Avaliação da libertação de azoto a partir de correctivos orgânicos utilizando membranas de troca aniónica e um medidor de clorofila SPAD-502 Nitrogen release from organic amendments assessed by using anion exchange membranes and the SPAD-502 chlorophyll meter

    Directory of Open Access Journals (Sweden)

    A. Pereira

    2009-01-01

    senescência por falta de azoto.Results from pot experiments where anion exchange membranes (MTA were inserted into the soil to monitor soil nitrate levels over time, and the plant N nutritional status assessed with a SPAD-502 chlorophyll meter, are reported in this work. Maize was grown in the summer season and turnip and rye in the winter period. Maize was sown on June 5, 2004, and turnip and rye on September 23, 2004. The plants were subjected to the following treatments: Nutrisoil (Nut; Beiraadubo (Bei; Phenix (Phe; Vegethumus (Veg; cow manure (EB; chestnut fruit bark (CC; ammonium nitrate (NA; and control treatment, without N fertilization (T. Two weeks after the maize was sown, soil nitrate levels extracted by MTA ranged between 18.9 and 239.0 mg L-1 in the CC and Bei treatments, respectively. In the first week of August mean soil nitrate values ranged between 12.9 and 52.3 mg L-1 in the CC and Bei treatments. In September, the last sampling date, mean soil nitrate levels were found to be in the range of 9.7 and 67.9 mg L-1 in the CC and Nut treatments. Relationships between MTA and SPAD results with dry matter yield and N uptake were established. The MTA were able to differentiate well as the organic amendments released their N during the season and this aspect influenced N uptake and plant growth. SPAD readings were also a good index of plant N nutritional status. SPAD values were linearly related with dry matter yield and N uptake. In this study, where the pots were managed to avoid nitrate leaching and denitrification, winter grown species recovered the residual N of maize fertilization. At the end of experiment the plants showed senescent leaves with deep N deficiency symptoms.

  17. Recent advances on polymeric membranes for membrane reactors

    KAUST Repository

    Buonomenna, M. G.

    2012-06-24

    Membrane reactors are generally applied in high temperature reactions (>400 °C). In the field of fine chemical synthesis, however, much milder conditions are generally applicable and polymeric membranes were applied without their damage. The successful use of membranes in membrane reactors is primary the result of two developments concerning: (i) membrane materials and (ii) membrane structures. The selection of a suited material and preparation technique depends on the application the membrane is to be used in. In this chapter a review of up to date literature about polymers and configuration catalyst/ membranes used in some recent polymeric membrane reactors is given. The new emerging concept of polymeric microcapsules as catalytic microreactors has been proposed. © 2012 Bentham Science Publishers. All rights reserved.

  18. Flow and fouling in membrane filters: Effects of membrane morphology

    Science.gov (United States)

    Sanaei, Pejman; Cummings, Linda J.

    2015-11-01

    Membrane filters are widely-used in microfiltration applications. Many types of filter membranes are produced commercially, for different filtration applications, but broadly speaking the requirements are to achieve fine control of separation, with low power consumption. The answer to this problem might seem obvious: select the membrane with the largest pore size and void fraction consistent with the separation requirements. However, membrane fouling (an inevitable consequence of successful filtration) is a complicated process, which depends on many parameters other than membrane pore size and void fraction; and which itself greatly affects the filtration process and membrane functionality. In this work we formulate mathematical models that can (i) account for the membrane internal morphology (internal structure, pore size & shape, etc.); (ii) fouling of membranes with specific morphology; and (iii) make some predictions as to what type of membrane morphology might offer optimum filtration performance.

  19. Polyurethane Nanofiber Membranes for Waste Water Treatment by Membrane Distillation

    Directory of Open Access Journals (Sweden)

    T. Jiříček

    2017-01-01

    Full Text Available Self-sustained electrospun polyurethane nanofiber membranes were manufactured and tested on a direct-contact membrane distillation unit in an effort to find the optimum membrane thickness to maximize flux rate and minimize heat losses across the membrane. Also salt retention and flux at high salinities up to 100 g kg−1 were evaluated. Even though the complex structure of nanofiber layers has extreme specific surface and porosity, membrane performance was surprisingly predictable; the highest flux was achieved with the thinnest membranes and the best energy efficiency was achieved with the thickest membranes. All membranes had salt retention above 99%. Nanotechnology offers the potential to find modern solutions for desalination of waste waters, by introducing new materials with revolutionary properties, but new membranes must be developed according to the target application.

  20. Smart membranes for monitoring membrane based desalination processes

    KAUST Repository

    Laleg-Kirati, Taous-Meriem

    2017-10-12

    Various examples are related to smart membranes for monitoring membrane based process such as, e.g., membrane distillation processes. In one example, a membrane, includes a porous surface and a plurality of sensors (e.g., temperature, flow and/or impedance sensors) mounted on the porous surface. In another example, a membrane distillation (MD) process includes the membrane. Processing circuitry can be configured to monitor outputs of the plurality of sensors. The monitored outputs can be used to determine membrane degradation, membrane fouling, or to provide an indication of membrane replacement or cleaning. The sensors can also provide temperatures or temperature differentials across the porous surface, which can be used to improve modeling or control the MD process.

  1. Protecting privacy in data release

    CERN Document Server

    Livraga, Giovanni

    2015-01-01

    This book presents a comprehensive approach to protecting sensitive information when large data collections are released by their owners. It addresses three key requirements of data privacy: the protection of data explicitly released, the protection of information not explicitly released but potentially vulnerable due to a release of other data, and the enforcement of owner-defined access restrictions to the released data. It is also the first book with a complete examination of how to enforce dynamic read and write access authorizations on released data, applicable to the emerging data outsou

  2. Triggered Release from Polymer Capsules

    Energy Technology Data Exchange (ETDEWEB)

    Esser-Kahn, Aaron P. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry; Odom, Susan A. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry; Sottos, Nancy R. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Materials Science and Engineering; White, Scott R. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Aerospace Engineering; Moore, Jeffrey S. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry

    2011-07-06

    Stimuli-responsive capsules are of interest in drug delivery, fragrance release, food preservation, and self-healing materials. Many methods are used to trigger the release of encapsulated contents. Here we highlight mechanisms for the controlled release of encapsulated cargo that utilize chemical reactions occurring in solid polymeric shell walls. Triggering mechanisms responsible for covalent bond cleavage that result in the release of capsule contents include chemical, biological, light, thermal, magnetic, and electrical stimuli. We present methods for encapsulation and release, triggering methods, and mechanisms and conclude with our opinions on interesting obstacles for chemically induced activation with relevance for controlled release.

  3. Physics of biological membranes

    Science.gov (United States)

    Mouritsen, Ole G.

    The biological membrane is a complex system consisting of an aqueous biomolecular planar aggregate of predominantly lipid and protein molecules. At physiological temperatures, the membrane may be considered a thin (˜50Å) slab of anisotropic fluid characterized by a high lateral mobility of the various molecular components. A substantial fraction of biological activity takes place in association with membranes. As a very lively piece of condensed matter, the biological membrane is a challenging research topic for both the experimental and theoretical physicists who are facing a number of fundamental physical problems including molecular self-organization, macromolecular structure and dynamics, inter-macromolecular interactions, structure-function relationships, transport of energy and matter, and interfacial forces. This paper will present a brief review of recent theoretical and experimental progress on such problems, with special emphasis on lipid bilayer structure and dynamics, lipid phase transitions, lipid-protein and lipid-cholesterol interactions, intermembrane forces, and the physical constraints imposed on biomembrane function and evolution. The paper advocates the dual point of view that there are a number of interesting physics problems in membranology and, at the same time, that the physical properties of biomembranes are important regulators of membrane function.

  4. Computational molecular modeling and structural rationalization for the design of a drug-loaded PLLA/PVA biopolymeric membrane

    International Nuclear Information System (INIS)

    Sibeko, B; Pillay, V; Choonara, Y E; Khan, R A; Danckwerts, M P; Modi, G; Iyuke, S E; Naidoo, D

    2009-01-01

    The purpose of this study was to design, characterize and assess the influence of triethanolamine (TEA) on the physicomechanical properties and release of methotrexate (MTX) from a composite biopolymeric membrane. Conjugated poly(L-lactic acid) (PLLA) and poly(vinyl alcohol) (PVA) membranes were prepared by immersion precipitation with and without the addition of TEA. Drug entrapment efficiency (DEE) and release studies were performed in phosphate buffered saline (pH 7.4, 37 deg. C). Scanning electron microscopy elucidated the membrane surface morphology. Computational and structural molecular modeling rationalized the potential mechanisms of membrane formation and MTX release. Bi-axial force-distance (F-D) extensibility profiles were generated to determine the membrane toughness, elasticity and fracturability. Membranes were significantly toughened by the addition of TEA as a discrete rubbery phase within the co-polymer matrix. MTX-TEA-PLLA-PVA membranes were tougher (F = 89 N) and more extensible (D = 8.79 mm) compared to MTX-PLLA-PVA (F = 35 N, D = 3.7 mm) membranes as a greater force of extension and fracture distance were required (N = 10). DEE values were relatively high (>80%, N = 5) for both formulations. Photomicrographs revealed distinct crystalline layered morphologies with macro-pores. MTX was released by tri-phasic kinetics with a lower fractional release of MTX from MTX-TEA-PLLA-PVA membranes compared to MTX-PLLA-PVA. TEA provided a synergistic approach to improving the membrane physicomechanical properties and modulation of MTX release. The composite biopolymeric membrane may therefore be suitable for the novel delivery of MTX in the treatment of chronic primary central nervous system lymphoma.

  5. Liver plasma membranes: an effective method to analyze membrane proteome.

    Science.gov (United States)

    Cao, Rui; Liang, Songping

    2012-01-01

    Plasma membrane proteins are critical for the maintenance of biological systems and represent important targets for the treatment of disease. The hydrophobicity and low abundance of plasma membrane proteins make them difficult to analyze. The protocols given here are the efficient isolation/digestion procedures for liver plasma membrane proteomic analysis. Both protocol for the isolation of plasma membranes and protocol for the in-gel digestion of gel-embedded plasma membrane proteins are presented. The later method allows the use of a high detergent concentration to achieve efficient solubilization of hydrophobic plasma membrane proteins while avoiding interference with the subsequent LC-MS/MS analysis.

  6. Palmitoylethanolamide Inhibits Glutamate Release in Rat Cerebrocortical Nerve Terminals

    Directory of Open Access Journals (Sweden)

    Tzu-Yu Lin

    2015-03-01

    Full Text Available The effect of palmitoylethanolamide (PEA, an endogenous fatty acid amide displaying neuroprotective actions, on glutamate release from rat cerebrocortical nerve terminals (synaptosomes was investigated. PEA inhibited the Ca2+-dependent release of glutamate, which was triggered by exposing synaptosomes to the potassium channel blocker 4-aminopyridine. This release inhibition was concentration dependent, associated with a reduction in cytosolic Ca2+ concentration, and not due to a change in synaptosomal membrane potential. The glutamate release-inhibiting effect of PEA was prevented by the Cav2.1 (P/Q-type channel blocker ω-agatoxin IVA or the protein kinase A inhibitor H89, not affected by the intracellular Ca2+ release inhibitors dantrolene and CGP37157, and partially antagonized by the cannabinoid CB1 receptor antagonist AM281. Based on these results, we suggest that PEA exerts its presynaptic inhibition, likely through a reduction in the Ca2+ influx mediated by Cav2.1 (P/Q-type channels, thereby inhibiting the release of glutamate from rat cortical nerve terminals. This release inhibition might be linked to the activation of presynaptic cannabinoid CB1 receptors and the suppression of the protein kinase A pathway.

  7. Aquaporin-2 membrane targeting

    DEFF Research Database (Denmark)

    Olesen, Emma T B; Fenton, Robert A

    2017-01-01

    The targeting of the water channel aquaporin-2 (AQP2) to the apical plasma membrane of kidney collecting duct principal cells is regulated mainly by the antidiuretic peptide hormone arginine vasopressin (AVP). This process is of crucial importance for the maintenance of body water homeostasis...... of aquaporin-2 (AQP2) to the apical plasma membrane of collecting duct (CD) principal cells (10, 20). This process is mainly regulated by the actions of AVP on the type 2 AVP receptor (V2R), although the V1a receptor may also play a minor role (26). The V2R is classified within the group of 7-transmembrane....... For example, 1) stimulation with the nonspecific AC activator forskolin increases AQP2 membrane accumulation in a mouse cortical collecting duct cell line [e.g., Norregaard et al. (16)]; 2) cAMP increases CD water permeability (15); 3) the cAMP-activated protein kinase A (PKA) can phosphorylate AQP2 on its...

  8. Destabilization of the Outer and Inner Mitochondrial Membranes by Core and Linker Histones

    Science.gov (United States)

    Cascone, Annunziata; Bruelle, Celine; Lindholm, Dan; Bernardi, Paolo; Eriksson, Ove

    2012-01-01

    Background Extensive DNA damage leads to apoptosis. Histones play a central role in DNA damage sensing and may mediate signals of genotoxic damage to cytosolic effectors including mitochondria. Methodology/Principal Findings We have investigated the effects of histones on mitochondrial function and membrane integrity. We demonstrate that both linker histone H1 and core histones H2A, H2B, H3, and H4 bind strongly to isolated mitochondria. All histones caused a rapid and massive release of the pro-apoptotic intermembrane space proteins cytochrome c and Smac/Diablo, indicating that they permeabilize the outer mitochondrial membrane. In addition, linker histone H1, but not core histones, permeabilized the inner membrane with a collapse of the membrane potential, release of pyridine nucleotides, and mitochondrial fragmentation. Conclusions We conclude that histones destabilize the mitochondrial membranes, a mechanism that may convey genotoxic signals to mitochondria and promote apoptosis following DNA damage. PMID:22523586

  9. Membrane adsorber for endotoxin removal

    Directory of Open Access Journals (Sweden)

    Karina Moita de Almeida

    Full Text Available ABSTRACT The surface of flat-sheet nylon membranes was modified using bisoxirane as the spacer and polyvinyl alcohol as the coating polymer. The amino acid histidine was explored as a ligand for endotoxins, aiming at its application for endotoxin removal from aqueous solutions. Characterization of the membrane adsorber, analysis of the depyrogenation procedures and the evaluation of endotoxin removal efficiency in static mode are discussed. Ligand density of the membranes was around 7 mg/g dry membrane, allowing removal of up to 65% of the endotoxins. The performance of the membrane adsorber prepared using nylon coated with polyvinyl alcohol and containing histidine as the ligand proved superior to other membrane adsorbers reported in the literature. The lack of endotoxin adsorption on nylon membranes without histidine confirmed that endotoxin removal was due to the presence of the ligand at the membrane surface. Modified membranes were highly stable, exhibiting a lifespan of approximately thirty months.

  10. Hybrid Filter Membrane

    Science.gov (United States)

    Laicer, Castro; Rasimick, Brian; Green, Zachary

    2012-01-01

    Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of

  11. Riola release report

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, E.C.

    1983-08-04

    Eleven hours after execution of the Riola Event (at 0826 PDT on 25 September 1980) in hole U2eq of the Nevada Test Site (NTS), a release of radioactivity began. When the seepage stopped at about noon the following day, up to some 3200 Ci of activity had been dispersed by light variable winds. On 26 September, examination of the geophone records showed six hours of low-level, but fairly continuous, activity before the release. Electrical measurements indicated that most cables were still intact to a depth below the stemming platform. A survey of the ground zero area showed that the seepage came through cracks between the surface conductor and the pad, through cracks in the pad, and through a crack adjacent to the pad around the mousehole (a small hole adjacent to the emplacement hole). To preclude undue radiation exposure or injury from a surprise subsidence, safety measures were instituted. Tritium seepage was suffucient to postpone site activities until a box and pipeline were emplaced to contain and remove the gas. Radiation release modeling and calculations were generally consistent with observations. Plug-hole interaction calculations showed that the alluvium near the bottom of the plug may have been overstressed and that improvements in the design of the plug-medium interface can be made. Experimental studies verified that the surface appearance of the plug core was caused by erosion, but, assuming a normal strength for the plug material, that erosion alone could not account for the disappearance of such a large portion of the stemming platform. Samples from downhole plug experiments show that the plug may have been considerably weaker than had been indicted by quality assurance (QA) samples. 19 references, 32 figures, 10 tables.

  12. Riola release report

    International Nuclear Information System (INIS)

    Woodward, E.C.

    1983-01-01

    Eleven hours after execution of the Riola Event (at 0826 PDT on 25 September 1980) in hole U2eq of the Nevada Test Site (NTS), a release of radioactivity began. When the seepage stopped at about noon the following day, up to some 3200 Ci of activity had been dispersed by light variable winds. On 26 September, examination of the geophone records showed six hours of low-level, but fairly continuous, activity before the release. Electrical measurements indicated that most cables were still intact to a depth below the stemming platform. A survey of the ground zero area showed that the seepage came through cracks between the surface conductor and the pad, through cracks in the pad, and through a crack adjacent to the pad around the mousehole (a small hole adjacent to the emplacement hole). To preclude undue radiation exposure or injury from a surprise subsidence, safety measures were instituted. Tritium seepage was suffucient to postpone site activities until a box and pipeline were emplaced to contain and remove the gas. Radiation release modeling and calculations were generally consistent with observations. Plug-hole interaction calculations showed that the alluvium near the bottom of the plug may have been overstressed and that improvements in the design of the plug-medium interface can be made. Experimental studies verified that the surface appearance of the plug core was caused by erosion, but, assuming a normal strength for the plug material, that erosion alone could not account for the disappearance of such a large portion of the stemming platform. Samples from downhole plug experiments show that the plug may have been considerably weaker than had been indicted by quality assurance (QA) samples. 19 references, 32 figures, 10 tables

  13. Allegheny County Toxics Release Inventory

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — The Toxics Release Inventory (TRI) data provides information about toxic substances released into the environment or managed through recycling, energy recovery, and...

  14. Mitigating leaks in membranes

    Energy Technology Data Exchange (ETDEWEB)

    Karnik, Rohit N.; Bose, Suman; Boutilier, Michael S.H.; Hadjiconstantinou, Nicolas G.; Jain, Tarun Kumar; O' Hern, Sean C.; Laoui, Tahar; Atieh, Muataz A.; Jang, Doojoon

    2018-02-27

    Two-dimensional material based filters, their method of manufacture, and their use are disclosed. In one embodiment, a membrane may include an active layer including a plurality of defects and a deposited material associated with the plurality of defects may reduce flow therethrough. Additionally, a majority of the active layer may be free from the material. In another embodiment, a membrane may include a porous substrate and an atomic layer deposited material disposed on a surface of the porous substrate. The atomic layer deposited material may be less hydrophilic than the porous substrate and an atomically thin active layer may be disposed on the atomic layer deposited material.

  15. Membrane accessibility of glutathione

    DEFF Research Database (Denmark)

    Garcia, Almudena; Eljack, N., D.; Sani, ND

    2015-01-01

    Regulation of the ion pumping activity of the Na(+),K(+)-ATPase is crucial to the survival of animal cells. Recent evidence has suggested that the activity of the enzyme could be controlled by glutathionylation of cysteine residue 45 of the β-subunit. Crystal structures so far available indicate...... that this cysteine is in a transmembrane domain of the protein. Here we have analysed via fluorescence and NMR spectroscopy as well as molecular dynamics simulations whether glutathione is able to penetrate into the interior of a lipid membrane. No evidence for any penetration of glutathione into the membrane...

  16. Fouling resistant membrane spacers

    KAUST Repository

    Ghaffour, Noreddine

    2017-10-12

    Disclosed herein are spacers having baffle designs and perforations for efficiently and effectively separating one or more membrane layers a membrane filtration system. The spacer (504) includes a body (524) formed at least in part by baffles (520) that are interconnected, and the baffles define boundaries of openings or apertures (525) through a thickness direction of the body of the spacer. Alternatively or additionally, passages or perforations (526A, 526B) may be present in the spacer layer or baffles for fluid flow there through, with the passages and baffles having a numerous different shapes and sizes.

  17. Organic separations with membranes

    International Nuclear Information System (INIS)

    Funk, E.W.

    1993-01-01

    This paper presents an overview of present and emerging applications of membrane technology for the separation and purification of organic materials. This technology is highly relevant for programs aimed at minimizing waste in processing and in the treatment of gaseous and liquid effluents. Application of membranes for organic separation is growing rapidly in the petrochemical industry to simplify processing and in the treatment of effluents, and it is expected that this technology will be useful in numerous other industries including the processing of nuclear waste materials

  18. Structure and physical properties of bio membranes and model membranes

    International Nuclear Information System (INIS)

    Tibor Hianik

    2006-01-01

    Bio membranes belong to the most important structures of the cell and the cell organelles. They play not only structural role of the barrier separating the external and internal part of the membrane but contain also various functional molecules, like receptors, ionic channels, carriers and enzymes. The cell membrane also preserves non-equilibrium state in a cell which is crucial for maintaining its excitability and other signaling functions. The growing interest to the bio membranes is also due to their unique physical properties. From physical point of view the bio membranes, that are composed of lipid bilayer into which are incorporated integral proteins and on their surface are anchored peripheral proteins and polysaccharides, represent liquid s crystal of smectic type. The bio membranes are characterized by anisotropy of structural and physical properties. The complex structure of bio membranes makes the study of their physical properties rather difficult. Therefore several model systems that mimic the structure of bio membranes were developed. Among them the lipid monolayers at an air-water interphase, bilayer lipid membranes, supported bilayer lipid membranes and liposomes are most known. This work is focused on the introduction into the physical word of the bio membranes and their models. After introduction to the membrane structure and the history of its establishment, the physical properties of the bio membranes and their models are stepwise presented. The most focus is on the properties of lipid monolayers, bilayer lipid membranes, supported bilayer lipid membranes and liposomes that were most detailed studied. This lecture has tutorial character that may be useful for undergraduate and graduate students in the area of biophysics, biochemistry, molecular biology and bioengineering, however it contains also original work of the author and his co-worker and PhD students, that may be useful also for specialists working in the field of bio membranes and model

  19. Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

    Directory of Open Access Journals (Sweden)

    Mourad Laqbaqbi

    2017-03-01

    Full Text Available Various membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD, osmotic distillation (OD and osmotic membrane distillation (OMD use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED, membrane capacitive deionization (MCD, reverse osmosis (RO, nanofiltration (NF, ultrafiltration (UF, microfiltration (MF, etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling, fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application.

  20. Membrane order in the plasma membrane and endocytic recycling compartment.

    Science.gov (United States)

    Iaea, David B; Maxfield, Frederick R

    2017-01-01

    The cholesterol content of membranes plays an important role in organizing membranes for signal transduction and protein trafficking as well as in modulating the biophysical properties of membranes. While the properties of model or isolated membranes have been extensively studied, there has been little evaluation of internal membranes in living cells. Here, we use a Nile Red based probe, NR12S, and ratiometric live cell imaging, to analyze the membrane order of the plasma membrane and endocytic recycling compartment. We find that after a brief incubation to allow endocytosis, NR12S is distributed between the plasma membrane and the endocytic recycling compartment. The NR12S reports that the endocytic recycling compartment is more highly ordered than the plasma membrane. We also find that the plasma membrane and the endocytic recycling compartment are differentially affected by altering cellular cholesterol levels. The membrane order of the plasma membrane, but not the endocytic recycling compartment, is altered significantly when cellular cholesterol content is increased or decreased by 20%. These results demonstrate that changes in cellular cholesterol differentially alter membrane order within different organelles.

  1. Regulation of vesicular traffic by a GTP-binding protein on the cytoplasmic surface of secretory vesicles in yeast

    International Nuclear Information System (INIS)

    Novick, P.J.; Goud, B.; Salminen, A.; Walworth, N.C.; Nair, J.; Potenza, M.

    1988-01-01

    Vesicular transport is an important mechanism for the intracellular traffic of proteins and lipids in eukaryotic cells. Vesicles mediate the passage of proteins between the various organelles of the secretory pathway and the exocytic release of these proteins into the extracellular environment. Vesicles also mediate the uptake of proteins and fluid from the external environment, delivering them to endosomes. Despite the generality of the vesicular transport mechanism, the process is not yet understood at a molecular level. The key questions that are addressed are (1) How are vesicles formed from the membrane of the donor organelle? (2) How are these vesicles transported? (3) How do the vesicles recognize the membrane of the target (acceptor) organelle? (4) How is membrane fusion accomplished? The genetic flexibility of yeast has been exploited to identify components of the cellular machinery required for vesicular transport

  2. Enzymatic Oxidation of Cholesterol: Properties and Functional Effects of Cholestenone in Cell Membranes

    DEFF Research Database (Denmark)

    Neuvonen, M.; Manna, M.; Mokkila, S.

    2014-01-01

    of cholestenone using simulations and cell biological experiments and assessed the functional effects of cholestenone in human cells. Atomistic simulations predicted that cholestenone reduces membrane order, undergoes faster flip-flop and desorbs more readily from membranes than cholesterol. In primary human...... fibroblasts, cholestenone was released from membranes to physiological extracellular acceptors more avidly than cholesterol, but without acceptors it remained in cells over a day. To address the functional effects of cholestenone, we studied fibroblast migration during wound healing. When cells were either...... similarly to control cells. Thus, cholesterol oxidation produces long-term functional effects in cells and these are in part due to the generated membrane active cholestenone....

  3. Impact of lysosome status on extracellular vesicle content and release.

    Science.gov (United States)

    Eitan, Erez; Suire, Caitlin; Zhang, Shi; Mattson, Mark P

    2016-12-01

    Extracellular vesicles (EVs) are nanoscale size bubble-like membranous structures released from cells. EVs contain RNA, lipids and proteins and are thought to serve various roles including intercellular communication and removal of misfolded proteins. The secretion of misfolded and aggregated proteins in EVs may be a cargo disposal alternative to the autophagy-lysosomal and ubiquitin-proteasome pathways. In this review we will discuss the importance of lysosome functionality for the regulation of EV secretion and content. Exosomes are a subtype of EVs that are released by the fusion of multivesicular bodies (MVB) with the plasma membrane. MVBs can also fuse with lysosomes, and the trafficking pathway of MVBs can therefore determine whether or not exosomes are released from cells. Here we summarize data from studies of the effects of lysosome inhibition on the secretion of EVs and on the possibility that cells compensate for lysosome malfunction by disposal of potentially toxic cargos in EVs. A better understanding of the molecular mechanisms that regulate trafficking of MVBs to lysosomes and the plasma membrane may advance an understanding of diseases in which pathogenic proteins, lipids or infectious agents accumulate within or outside of cells. Copyright © 2016. Published by Elsevier B.V.

  4. Effect of in vitro inorganic lead on dopamine release from superfused rat striatal synaptosomes

    International Nuclear Information System (INIS)

    Minnema, D.J.; Greenland, R.D.; Michaelson, I.A.

    1986-01-01

    The effect of inorganic lead in vitro in several aspects of [ 3 H]dopamine release from superfused rat striatal synaptosomes was examined. Under conditions of spontaneous release, lead (1-30 microM) induced dopamine release in a concentration-dependent manner. The onset of the lead-induced release was delayed by approximately 15-30 sec. The magnitude of dopamine release induced by lead was increased when calcium was removed from the superfusing buffer. Lead-induced release was unaffected in the presence of putative calcium, sodium, and/or potassium channel blockers (nickel, tetrodotoxin, tetraethylammonium, respectively). Depolarization-evoked dopamine release, produced by a 1-sec exposure to 61 mM potassium, was diminished at calcium concentrations below 0.254 mM. The onset of depolarization-evoked release was essentially immediate following exposure of the synaptosomes to high potassium. The combination of lead (3 or 10 microM) with high potassium reduced the magnitude of depolarization-evoked dopamine release. This depression of depolarization-evoked release by lead was greater in the presence of 0.25 mM than 2.54 mM calcium in the superfusing buffer. These findings demonstrate multiple actions of lead on synaptosomal dopamine release. Lead can induce dopamine release by yet unidentified neuronal mechanisms independent of external calcium. Lead can also reduce depolarization-evoked dopamine release by apparent competition with calcium influx at the neuronal membrane calcium channel

  5. The Emerging Role of Extracellular Vesicle-Mediated Drug Resistance in Cancers: Implications in Advanced Prostate Cancer.

    Science.gov (United States)

    Soekmadji, Carolina; Nelson, Colleen C

    2015-01-01

    Emerging evidence has shown that the extracellular vesicles (EVs) regulate various biological processes and can control cell proliferation and survival, as well as being involved in normal cell development and diseases such as cancers. In cancer treatment, development of acquired drug resistance phenotype is a serious issue. Recently it has been shown that the presence of multidrug resistance proteins such as Pgp-1 and enrichment of the lipid ceramide in EVs could have a role in mediating drug resistance. EVs could also mediate multidrug resistance through uptake of drugs in vesicles and thus limit the bioavailability of drugs to treat cancer cells. In this review, we discussed the emerging evidence of the role EVs play in mediating drug resistance in cancers and in particular the role of EVs mediating drug resistance in advanced prostate cancer. The role of EV-associated multidrug resistance proteins, miRNA, mRNA, and lipid as well as the potential interaction(s) among these factors was probed. Lastly, we provide an overview of the current available treatments for advanced prostate cancer, considering where EVs may mediate the development of resistance against these drugs.

  6. Paromomycin affects translation and vesicle-mediated trafficking as revealed by proteomics of paromomycin -susceptible -resistant Leishmania donovani.

    Directory of Open Access Journals (Sweden)

    Bhavna Chawla

    Full Text Available Leishmania donovani is a protozoan parasite that causes visceral leishmaniasis (VL and is responsible for significant mortality and morbidity. Increasing resistance towards antimonial drugs poses a great challenge in chemotherapy of VL. Paromomycin is an aminoglycosidic antibiotic and is one of the drugs currently being used in the chemotherapy of cutaneous and visceral leishmaniasis. To understand the mode of action of this antibiotic at the molecular level, we have investigated the global proteome differences between the wild type AG83 strain and a paromomycin resistant (PRr strain of L. donovani. Stable isotope labeling of amino acids in cell culture (SILAC followed by quantitative mass spectrometry of the wild type AG83 strain and the paromomycin resistant (PRr strain identified a total of 226 proteins at ≥ 95% confidence. Data analysis revealed upregulation of 29 proteins and down-regulation of 21 proteins in the PRr strain. Comparative proteomic analysis of the wild type and the paromomycin resistant strains showed upregulation of the ribosomal proteins in the resistant strain indicating role in translation. Elevated levels of glycolytic enzymes and stress proteins were also observed in the PRr strain. Most importantly, we observed upregulation of proteins that may have a role in intracellular survival and vesicular trafficking in the PRr strain. Furthermore, ultra-structural analysis by electron microscopy demonstrated increased number of vesicular vacuoles in PRr strain when compared to the wild-type strain. Drug affinity pull-down assay followed by mass spectrometery identified proteins in L. donovani wild type strain that were specifically and covalently bound to paromomycin. These results provide the first comprehensive insight into the mode of action and underlying mechanism of resistance to paromomycin in Leishmania donovani.

  7. Extracellular vesicle-mediated transfer of genetic information between the hematopoietic system and the brain in response to inflammation.

    Directory of Open Access Journals (Sweden)

    Kirsten Ridder

    2014-06-01

    Full Text Available Mechanisms behind how the immune system signals to the brain in response to systemic inflammation are not fully understood. Transgenic mice expressing Cre recombinase specifically in the hematopoietic lineage in a Cre reporter background display recombination and marker gene expression in Purkinje neurons. Here we show that reportergene expression in neurons is caused by intercellular transfer of functional Cre recombinase messenger RNA from immune cells into neurons in the absence of cell fusion. In vitro purified secreted extracellular vesicles (EVs from blood cells contain Cre mRNA, which induces recombination in neurons when injected into the brain. Although Cre-mediated recombination events in the brain occur very rarely in healthy animals, their number increases considerably in different injury models, particularly under inflammatory conditions, and extend beyond Purkinje neurons to other neuronal populations in cortex, hippocampus, and substantia nigra. Recombined Purkinje neurons differ in their miRNA profile from their nonrecombined counterparts, indicating physiological significance. These observations reveal the existence of a previously unrecognized mechanism to communicate RNA-based signals between the hematopoietic system and various organs, including the brain, in response to inflammation.

  8. Isolation of Synaptosomes, Synaptic Plasma Membranes, and Synaptic Junctional Complexes.

    Science.gov (United States)

    Michaelis, Mary L; Jiang, Lei; Michaelis, Elias K

    2017-01-01

    Isolation of synaptic nerve terminals or synaptosomes provides an opportunity to study the process of neurotransmission at many levels and with a variety of approaches. For example, structural features of the synaptic terminals and the organelles within them, such as synaptic vesicles and mitochondria, have been elucidated with electron microscopy. The postsynaptic membranes are joined to the presynaptic "active zone" of transmitter release through cell adhesion molecules and remain attached throughout the isolation of synaptosomes. These "post synaptic densities" or "PSDs" contain the receptors for the transmitters released from the nerve terminals and can easily be seen with electron microscopy. Biochemical and cell biological studies with synaptosomes have revealed which proteins and lipids are most actively involved in synaptic release of neurotransmitters. The functional properties of the nerve terminals, such as responses to depolarization and the uptake or release of signaling molecules, have also been characterized through the use of fluorescent dyes, tagged transmitters, and transporter substrates. In addition, isolated synaptosomes can serve as the starting material for the isolation of relatively pure synaptic plasma membranes (SPMs) that are devoid of organelles from the internal environment of the nerve terminal, such as mitochondria and synaptic vesicles. The isolated SPMs can reseal and form vesicular structures in which transport of ions such as sodium and calcium, as well as solutes such as neurotransmitters can be studied. The PSDs also remain associated with the presynaptic membranes during isolation of SPM fractions, making it possible to isolate the synaptic junctional complexes (SJCs) devoid of the rest of the plasma membranes of the nerve terminals and postsynaptic membrane components. Isolated SJCs can be used to identify the proteins that constitute this highly specialized region of neurons. In this chapter, we describe the steps involved

  9. Obtaining membranes for alternative treatment hydrogels of cutaneous leishmaniasis

    International Nuclear Information System (INIS)

    Oliveira, Maria Jose Alves de

    2013-01-01

    Polymeric Hydrogels formed by crosslinked polymeric chains were obtained by ionizing radiation process according to Rosiak technique. In the last 40 years the use of hydrogels has been investigated for various applications as curatives. In this work hydrogel membranes were synthesized with poly (N-2-pyrrolidone) (PVP), poly (vinyl alcohol) (PVA), chitosan and laponita clay for use as a vehicle for controlled glucantime release on the surface of skin tissues injured by leishmaniasis. Leishmaniasis is a disease caused by a protozoan parasite of the genus Leishmania transmitted by the bite of phlebotomies sandfly. The traditional treatment of patients infected by these parasites is done with pentavalent antimony in injectable form. However, these antimonates are highly toxic and cause side effects in these patients. In addition, patients with heart and kidney disease can not use this treatment. In treatment with drug delivery hydrogel membrane applied on the surface of leishmaniasis injured tissues the drug is released directly to the wound in a controlled manner, reducing the side effects. Membranes prepared in this study were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), swelling, gel fraction, infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The characterizations of cytotoxicity and drug release were made 'in vitro' and 'in vivo' with functional test according to ethical protocol of the Division of Infectious and Parasitic Diseases at the Hospital of Clinics, Sao Paulo University-School of Medicine, University. The 'in vivo' test of these membranes proved to be effective in controlled release of drugs directly into leishmaniasis damaged tissues. Results of 'in vivo' tests using PVP/PVAl / clay 1,5% and glucantime membrane showed remarkable contribution to wound reduction and cure in clinical therapy. (author)

  10. Fabrication of electrospun nanofibrous membranes for membrane distillation application

    KAUST Repository

    Francis, Lijo; Maab, Husnul; Alsaadi, Ahmad Salem; Nunes, Suzana Pereira; Ghaffour, NorEddine; Amy, Gary L.

    2013-01-01

    Nanofibrous membranes of Matrimid have been successfully fabricated using an electrospinning technique under optimized conditions. Nanofibrous membranes are found to be highly hydrophobic with a high water contact angle of 130°. Field emission

  11. Giant plasma membrane vesicles: models for understanding membrane organization.

    Science.gov (United States)

    Levental, Kandice R; Levental, Ilya

    2015-01-01

    The organization of eukaryotic membranes into functional domains continues to fascinate and puzzle cell biologists and biophysicists. The lipid raft hypothesis proposes that collective lipid interactions compartmentalize the membrane into coexisting liquid domains that are central to membrane physiology. This hypothesis has proven controversial because such structures cannot be directly visualized in live cells by light microscopy. The recent observations of liquid-liquid phase separation in biological membranes are an important validation of the raft hypothesis and enable application of the experimental toolbox of membrane physics to a biologically complex phase-separated membrane. This review addresses the role of giant plasma membrane vesicles (GPMVs) in refining the raft hypothesis and expands on the application of GPMVs as an experimental model to answer some of key outstanding problems in membrane biology. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. A simple route to develop transparent doxorubicin-loaded nanodiamonds/cellulose nanocomposite membranes as potential wound dressings.

    Science.gov (United States)

    Luo, Xiaogang; Zhang, Hao; Cao, Zhenni; Cai, Ning; Xue, Yanan; Yu, Faquan

    2016-06-05

    The objective of this study is to develop transparent porous nanodiamonds/cellulose nanocomposite membranes with controlled release of doxorubicin for potential applications as wound dressings, which were fabricated by tape casting method from dispersing carboxylated nanodiamonds and dissolving cellulose homogeneously in 7 wt% NaOH/12 wt% urea aqueous solution. By adjusting the carboxylated nanodiamonds content, various nanocomposite membranes were obtained. The structure and properties of these membranes have been investigated by light transmittance measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), tensile tests, water loss analyses, etc. The drug loading and release was investigated using doxorubicin hydrochloride as a model drug. In vitro cytotoxicity assay of the membranes was also studied. This work presented a proof-of-concept utility of these membranes for loading and release of bioactive compounds to be employed as a candidate for wound dressing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Adaptive silicone-membrane lenses: planar vs. shaped membrane

    CSIR Research Space (South Africa)

    Schneider, F

    2009-08-01

    Full Text Available Engineering, Georges-Koehler-Allee 102, Freiburg 79110, Germany florian.schneider@imtek.uni-freiburg.de ABSTRACT We compare the performance and optical quality of two types of adaptive fluidic silicone-membrane lenses. The membranes feature either a...-membrane lenses: planar vs. shaped membrane Florian Schneider1,2, Philipp Waibel2 and Ulrike Wallrabe2 1 CSIR, Materials Science and Manufacturing, PO Box 395, Pretoria 0001, South Africa 2 University of Freiburg – IMTEK, Department of Microsystems...

  14. Nanodisc-solubilized membrane protein library reflects the membrane proteome

    OpenAIRE

    Marty, Michael T.; Wilcox, Kyle C.; Klein, William L.; Sligar, Stephen G.

    2013-01-01

    The isolation and identification of unknown membrane proteins offers the prospect of discovering new pharmaceutical targets and identifying key biochemical receptors. However, interactions between membrane protein targets and soluble ligands are difficult to study in vitro due to the insolubility of membrane proteins in non-detergent systems. Nanodiscs, nanoscale discoidal lipid bilayers encircled by a membrane scaffold protein belt, have proven to be an effective platform to solubilize membr...

  15. Imaging of membranous dysmenorrhea

    Energy Technology Data Exchange (ETDEWEB)

    Rouanet, J.P.; Daclin, P.Y.; Turpin, F.; Karam, R.; Prayssac-Salanon, A. [Dept. of Radiology, C. M. C. Beausoleil, Montpellier (France); Courtieu, C.R. [Dept. of Gynecology, C. M. C. Beausoleil, Montpellier (France); Maubon, A.J. [Dept. of Radiology, C. M. C. Beausoleil, Montpellier (France); Dept. of Radiology, C. H. U. Dupuytren, Limoges (France)

    2001-06-01

    Membranous dysmenorrhea is an unusual clinical entity. It is characterized by the expulsion of huge fragments of endometrium during the menses, favored by hormonal abnormality or drug intake. This report describes a case with clinical, US, and MRI findings before the expulsion. Differential diagnoses are discussed. (orig.)

  16. Imaging of membranous dysmenorrhea

    International Nuclear Information System (INIS)

    Rouanet, J.P.; Daclin, P.Y.; Turpin, F.; Karam, R.; Prayssac-Salanon, A.; Courtieu, C.R.; Maubon, A.J.

    2001-01-01

    Membranous dysmenorrhea is an unusual clinical entity. It is characterized by the expulsion of huge fragments of endometrium during the menses, favored by hormonal abnormality or drug intake. This report describes a case with clinical, US, and MRI findings before the expulsion. Differential diagnoses are discussed. (orig.)

  17. HOLLOW FIBRE MEMBRANE

    NARCIS (Netherlands)

    Wessling, Matthias; Stamatialis, Dimitrios; Kopec, K.K.; Dutczak, S.M.

    2011-01-01

    The present invention relates to a process for manufacturing a hollow fibre membrane having a supporting layer and a separating layer, said process comprising: (a)extruding a spinning composition comprising a first polymer and a solvent for the first polymer through an inner annular orifice of a

  18. HOLLOW FIBRE MEMBRANE

    NARCIS (Netherlands)

    Wessling, Matthias; Stamatialis, Dimitrios; Kopec, K.K.; Dutczak, S.M.

    2013-01-01

    The present invention relates to a process for manufacturing a hollow fibre membrane having a supporting layer and a separating layer, said process comprising: (a) extruding a spinning composition comprising a first polymer and a solvent for the first polymer through an inner annular orifice of a

  19. Fusion of biological membranes

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 64; Issue 6. Fusion of biological membranes. K Katsov M Müller M Schick. Invited Talks:- Topic 11. Biologically motivated problems (protein-folding models, dynamics at the scale of the cell; biological networks, evolution models, etc.) Volume 64 Issue 6 June 2005 pp ...

  20. Membranes and Fluorescence microscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2009-01-01

    Fluorescence spectroscopy-based techniques using conventional fluorimeters have been extensively applied since the late 1960s to study different aspects of membrane-related phenomena, i.e., mainly relating to lipid-lipid and lipid-protein (peptide) interactions. Even though fluorescence...

  1. Bioelectrochemistry II membrane phenomena

    CERN Document Server

    Blank, M

    1987-01-01

    This book contains the lectures of the second course devoted to bioelectro­ chemistry, held within the framework of the International School of Biophysics. In this course another very large field of bioelectrochemistry, i. e. the field of Membrane Phenomena, was considered, which itself consists of several different, but yet related subfields. Here again, it can be easily stated that it is impossible to give a complete and detailed picture of all membrane phenomena of biological interest in a short course of about one and half week. Therefore the same philosophy, as the one of the first course, was followed, to select a series of lectures at postgraduate level, giving a synthesis of several membrane phenomena chosen among the most'important ones. These lectures should show the large variety of membrane-regulated events occurring in living bodies, and serve as sound interdisciplinary basis to start a special­ ized study of biological phenomena, for which the investigation using the dual approach, physico-che...

  2. Membrane Transfer Phenomena (MTP)

    Science.gov (United States)

    Mason, Larry

    1996-01-01

    Progress has been made in several areas of the definition, design, and development of the Membrane Transport Apparatus (MTA) instrument and associated sensors and systems. Progress is also reported in the development of software modules for instrument control, experimental image and data acquisition, and data analysis.

  3. Extracorporeal membrane oxygenation (ECMO)

    African Journals Online (AJOL)

    Extracorporeal membrane oxygenation (ECMO) is not a novel therapy in the true sense of the ... Intention-to-treat analysis showed benefit for ECMO, with a relative risk ... no doubt that VV-ECMO is an advance in medical technology, and that.

  4. Cobalt release from inexpensive jewellery

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Jellesen, Morten Stendahl; Menné, Torkil

    2010-01-01

    . Conclusions: This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future......Objectives: The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. Methods: The cobalt spot test was used to assess cobalt release from all items...

  5. Alternative energy efficient membrane bioreactor using reciprocating submerged membrane.

    Science.gov (United States)

    Ho, J; Smith, S; Roh, H K

    2014-01-01

    A novel membrane bioreactor (MBR) pilot system, using membrane reciprocation instead of air scouring, was operated at constant high flux and daily fluctuating flux to demonstrate its application under peak and diurnal flow conditions. Low and stable transmembrane pressure was achieved at 40 l/m(2)/h (LMH) by use of repetitive membrane reciprocation. The results reveal that the inertial forces acting on the membrane fibers effectively propel foulants from the membrane surface. Reciprocation of the hollow fiber membrane is beneficial for the constant removal of solids that may build up on the membrane surface and inside the membrane bundle. The membrane reciprocation in the reciprocating MBR pilot consumed less energy than coarse air scouring used in conventional MBR systems. Specific energy consumption for the membrane reciprocation was 0.072 kWh/m(3) permeate produced at 40 LMH flux, which is 75% less than for a conventional air scouring system as reported in literature without consideration of energy consumption for biological aeration (0.29 kWh/m(3)). The daily fluctuating flux test confirmed that the membrane reciprocation is effective to handle fluctuating flux up to 50 LMH. The pilot-scale reciprocating MBR system successfully demonstrated that fouling can be controlled via 0.43 Hz membrane reciprocation with 44 mm or higher amplitude.

  6. Recent advances on membranes and membrane reactors for hydrogen production

    NARCIS (Netherlands)

    Gallucci, F.; Fernandez Gesalaga, E.; Corengia, P.; Sint Annaland, van M.

    2013-01-01

    Membranes and membrane reactors for pure hydrogen production are widely investigated not only because of the important application areas of hydrogen, but especially because mechanically and chemically stable membranes with high perm-selectivity towards hydrogen are available and are continuously

  7. Influence of membrane properties on fouling in submerged membrane bioreactors

    NARCIS (Netherlands)

    van der Marel, P.; Zwijnenburg, A.; Kemperman, Antonius J.B.; Wessling, Matthias; Temmink, Hardy; van der Meer, Walterus Gijsbertus Joseph

    2010-01-01

    Polymeric flat-sheet membranes with different properties were used in filtration experiments with activated sludge from a pilot-scale MBR to investigate the influence of membrane pore size, surface porosity, pore morphology, and hydrophobicity on membrane fouling. An improved flux-step method was

  8. Nanodisc-solubilized membrane protein library reflects the membrane proteome.

    Science.gov (United States)

    Marty, Michael T; Wilcox, Kyle C; Klein, William L; Sligar, Stephen G

    2013-05-01

    The isolation and identification of unknown membrane proteins offers the prospect of discovering new pharmaceutical targets and identifying key biochemical receptors. However, interactions between membrane protein targets and soluble ligands are difficult to study in vitro due to the insolubility of membrane proteins in non-detergent systems. Nanodiscs, nanoscale discoidal lipid bilayers encircled by a membrane scaffold protein belt, have proven to be an effective platform to solubilize membrane proteins and have been used to study a wide variety of purified membrane proteins. This report details the incorporation of an unbiased population of membrane proteins from Escherichia coli membranes into Nanodiscs. This solubilized membrane protein library (SMPL) forms a soluble in vitro model of the membrane proteome. Since Nanodiscs contain isolated proteins or small complexes, the SMPL is an ideal platform for interactomics studies and pull-down assays of membrane proteins. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the protein population before and after formation of the Nanodisc library indicates that a large percentage of the proteins are incorporated into the library. Proteomic identification of several prominent bands demonstrates the successful incorporation of outer and inner membrane proteins into the Nanodisc library.

  9. Autophagosomal membranes assemble at ER-plasma membrane contact sites.

    Science.gov (United States)

    Nascimbeni, Anna Chiara; Codogno, Patrice; Morel, Etienne

    2017-01-01

    The biogenesis of autophagosome, the double membrane bound organelle related to macro-autophagy, is a complex event requiring numerous key-proteins and membrane remodeling events. Our recent findings identify the extended synaptotagmins, crucial tethers of Endoplasmic Reticulum-plasma membrane contact sites, as key-regulators of this molecular sequence.

  10. Red Blood Cell Membrane-Cloaked Nanoparticles For Drug Delivery

    Science.gov (United States)

    Carpenter, Cody Westcott

    Herein we describe the development of the Red Blood Cell coated nanoparticle, RBC-NP. Purified natural erythrocyte membrane is used to coat drug-loaded poly(lacticco-glycolic acid) (PLGA). Synthetic PLGA co-polymer is biocompatible and biodegradable and has already received US FDA approval for drug-delivery and diagnostics. This work looks specifically at the retention of immunosuppressive proteins on RBC-NPs, right-sidedness of natural RBC membranes interfacing with synthetic polymer nanoparticles, sustained and retarded drug release of RBC-NPs as well as further surface modification of RBC-NPs for increased targeting of model cancer cell lines.

  11. OXYGEN TRANSPORT CERAMIC MEMBRANES

    International Nuclear Information System (INIS)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-01-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques

  12. Deletions in the fifth alpha helix of HIV-1 matrix block virus release

    Energy Technology Data Exchange (ETDEWEB)

    Sanford, Bridget; Li, Yan; Maly, Connor J.; Madson, Christian J. [Department of Medical Microbiology and Immunology, Creighton University, 2500 California Plaza, Omaha, NE 68178 (United States); Chen, Han [Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE (United States); Zhou, You [Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE (United States); Nebraska Center for Virology, Lincoln, NE (United States); Belshan, Michael, E-mail: michaelbelshan@creighton.edu [Department of Medical Microbiology and Immunology, Creighton University, 2500 California Plaza, Omaha, NE 68178 (United States); Nebraska Center for Virology, Lincoln, NE (United States)

    2014-11-15

    The matrix (MA) protein of HIV-1 is the N-terminal component of the Gag structural protein and is critical for the early and late stages of viral replication. MA contains five α-helices (α1–α5). Deletions in the N-terminus of α5 as small as three amino acids impaired virus release. Electron microscopy of one deletion mutant (MA∆96-120) showed that its particles were tethered to the surface of cells by membranous stalks. Immunoblots indicated all mutants were processed completely, but mutants with large deletions had alternative processing intermediates. Consistent with the EM data, MA∆96-120 retained membrane association and multimerization capability. Co-expression of this mutant inhibited wild type particle release. Alanine scanning mutation in this region did not affect virus release, although the progeny virions were poorly infectious. Combined, these data demonstrate that structural ablation of the α5 of MA inhibits virus release. - Highlights: • Deletions were identified in the C-terminus of matrix that block virus release. • These deletion mutants still multimerized and associated with membranes. • TEM showed the mutant particles were tethered to the cell surface. • Amino acid mutagenesis of the region did not affect release. • The data suggests that disruption of matrix structure blocks virus release.

  13. Deletions in the fifth alpha helix of HIV-1 matrix block virus release

    International Nuclear Information System (INIS)

    Sanford, Bridget; Li, Yan; Maly, Connor J.; Madson, Christian J.; Chen, Han; Zhou, You; Belshan, Michael

    2014-01-01

    The matrix (MA) protein of HIV-1 is the N-terminal component of the Gag structural protein and is critical for the early and late stages of viral replication. MA contains five α-helices (α1–α5). Deletions in the N-terminus of α5 as small as three amino acids impaired virus release. Electron microscopy of one deletion mutant (MA∆96-120) showed that its particles were tethered to the surface of cells by membranous stalks. Immunoblots indicated all mutants were processed completely, but mutants with large deletions had alternative processing intermediates. Consistent with the EM data, MA∆96-120 retained membrane association and multimerization capability. Co-expression of this mutant inhibited wild type particle release. Alanine scanning mutation in this region did not affect virus release, although the progeny virions were poorly infectious. Combined, these data demonstrate that structural ablation of the α5 of MA inhibits virus release. - Highlights: • Deletions were identified in the C-terminus of matrix that block virus release. • These deletion mutants still multimerized and associated with membranes. • TEM showed the mutant particles were tethered to the cell surface. • Amino acid mutagenesis of the region did not affect release. • The data suggests that disruption of matrix structure blocks virus release

  14. Membrane distillation for milk concentration

    NARCIS (Netherlands)

    Moejes, S.N.; Romero Guzman, Maria; Hanemaaijer, J.H.; Barrera, K.H.; Feenstra, L.; Boxtel, van A.J.B.

    2015-01-01

    Membrane distillation is an emerging technology to concentrate liquid products while producing high quality water as permeate. Application for desalination has been studied extensively the past years, but membrane distillation has also potential to produce concentrated food products like

  15. Filtration characteristics in membrane bioreactors

    NARCIS (Netherlands)

    Evenblij, H.

    2006-01-01

    Causes of and remedies for membrane fouling in Membrane Bioreactors for wastewater treatment are only poorly understood and described in scientific literature. A Filtration Characterisation Installation and a measurement protocol were developed with the aim of a) unequivocally determination and

  16. From shell to membrane theory

    International Nuclear Information System (INIS)

    Destuynder, P.

    1981-02-01

    A new formulation of the membrane theory is presented in this paper. The assumptions which allow the Budiansky-Sanders' model or the membrane theory to be deduced from the three-dimensional case are pointed out [fr

  17. The destiny of Ca(2+) released by mitochondria.

    Science.gov (United States)

    Takeuchi, Ayako; Kim, Bongju; Matsuoka, Satoshi

    2015-01-01

    Mitochondrial Ca(2+) is known to regulate diverse cellular functions, for example energy production and cell death, by modulating mitochondrial dehydrogenases, inducing production of reactive oxygen species, and opening mitochondrial permeability transition pores. In addition to the action of Ca(2+) within mitochondria, Ca(2+) released from mitochondria is also important in a variety of cellular functions. In the last 5 years, the molecules responsible for mitochondrial Ca(2+) dynamics have been identified: a mitochondrial Ca(2+) uniporter (MCU), a mitochondrial Na(+)-Ca(2+) exchanger (NCLX), and a candidate for a mitochondrial H(+)-Ca(2+) exchanger (Letm1). In this review, we focus on the mitochondrial Ca(2+) release system, and discuss its physiological and pathophysiological significance. Accumulating evidence suggests that the mitochondrial Ca(2+) release system is not only crucial in maintaining mitochondrial Ca(2+) homeostasis but also participates in the Ca(2+) crosstalk between mitochondria and the plasma membrane and between mitochondria and the endoplasmic/sarcoplasmic reticulum.

  18. Fundamentals of membrane bioreactors materials, systems and membrane fouling

    CERN Document Server

    Ladewig, Bradley

    2017-01-01

    This book provides a critical, carefully researched, up-to-date summary of membranes for membrane bioreactors. It presents a comprehensive and self-contained outline of the fundamentals of membrane bioreactors, especially their relevance as an advanced water treatment technology. This outline helps to bring the technology to the readers’ attention, and positions the critical topic of membrane fouling as one of the key impediments to its more widescale adoption. The target readership includes researchers and industrial practitioners with an interest in membrane bioreactors.

  19. Cheap Thin Film Oxygen Membranes

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention provides a membrane, comprising a porous support layer a gas tight electronically and ionically conducting membrane layer and a catalyst layer, characterized in that the electronically and ionically conducting membrane layer is formed from a material having a crystallite...... structure with a crystal size of about 1 to 100 nm, and a method for producing same....

  20. Mesoporous and microporous titania membranes

    NARCIS (Netherlands)

    Sekulic, J.

    2004-01-01

    The research described in this thesis deals with the synthesis and properties of ceramic oxide membrane materials. Since most of the currently available inorganic membranes with required separation properties have limited reliability and long-term stability, membranes made of new oxide materials

  1. Membranes suited for immobilizing biomolecules

    NARCIS (Netherlands)

    2009-01-01

    The present invention relates to flow-through membranes suitable for the immobilization of biomols., methods for the prepn. of such membranes and the use of such membranes for the immobilization of biomols. and subsequent detection of immobilized biomols. The invention concerns a flow-through

  2. Characterization and quantitation of concanavalin A binding by plasma membrane enriched fractions from soybean root

    International Nuclear Information System (INIS)

    Berkowitz, R.L.; Travis, R.L.

    1981-01-01

    The binding of concanavalin A (Con A) to soybean root membranes in plasma membrane enriched fractions (recovered from the 34/45% interface of simplified discontinuous sucrose density gradients) was studied using a radiochemical assay employing tritated ( 3 H)-Con A. The effect of lectin concentration, time, and membrane protein concentration on the specific binding of 3 H-Con A by the membranes was evaluated. Kinetic analyses showed that Con A will react with membranes in that fraction in a characteristic and predictable manner. The parameters for an optimal and standard binding assay were established. Maximal binding occurred with Con A concentrations in the range of 8 to 16% of the total membrane protein with incubation times greater than 40 min at 22 C. Approximately 10 15 molecules of 3 H-Con A were bound per microgram of membrane protein at saturation. Binding was reversible. Greater than 92% of the total Con A bound at saturation was released by addition of α-methyl mannoside. A major peak of 3 H-Con A binding was also observed in fractions recovered from the 25/30% interface of a complex discontinuous sucrose density gradient when membranes were isolated in the absence of Mg 2+ . When high Mg 2+ was present in the isolation and gradient media, the peak was shifted to a fraction recovered from the 34/38% sucrose interface. These results suggest that Con A binding sites are also present on membranes of the endoplasmic reticulum. The amount of Con A bound by endoplasmic reticulum membranes was at least twice the amount bound by membranes in plasma membrane enriched fractions when binding was compared on a per unit membrane protein basis. In contrast, mitochondrial inner membranes, which equilibrate at the same density as plasma membranes, had little ability to bind the lectin

  3. Release of canine parvovirus from endocytic vesicles

    International Nuclear Information System (INIS)

    Suikkanen, Sanna; Antila, Mia; Jaatinen, Anne; Vihinen-Ranta, Maija; Vuento, Matti

    2003-01-01

    Canine parvovirus (CPV) is a small nonenveloped virus with a single-stranded DNA genome. CPV enters cells by clathrin-mediated endocytosis and requires an acidic endosomal step for productive infection. Virion contains a potential nuclear localization signal as well as a phospholipase A 2 like domain in N-terminus of VP1. In this study we characterized the role of PLA 2 activity on CPV entry process. PLA 2 activity of CPV capsids was triggered in vitro by heat or acidic pH. PLA 2 inhibitors inhibited the viral proliferation suggesting that PLA 2 activity is needed for productive infection. The N-terminus of VP1 was exposed during the entry, suggesting that PLA 2 activity might have a role during endocytic entry. The presence of drugs modifying endocytosis (amiloride, bafilomycin A 1 , brefeldin A, and monensin) caused viral proteins to remain in endosomal/lysosomal vesicles, even though the drugs were not able to inhibit the exposure of VP1 N-terminal end. These results indicate that the exposure of N-terminus of VP1 alone is not sufficient to allow CPV to proliferate. Some other pH-dependent changes are needed for productive infection. In addition to blocking endocytic entry, amiloride was able to block some postendocytic steps. The ability of CPV to permeabilize endosomal membranes was demonstrated by feeding cells with differently sized rhodamine-conjugated dextrans together with the CPV in the presence or in the absence of amiloride, bafilomycin A 1 , brefeldin A, or monensin. Dextran with a molecular weight of 3000 was released from vesicles after 8 h of infection, while dextran with a molecular weight of 10,000 was mainly retained in vesicles. The results suggest that CPV infection does not cause disruption of endosomal vesicles. However, the permeability of endosomal membranes apparently changes during CPV infection, probably due to the PLA 2 activity of the virus. These results suggest that parvoviral PLA 2 activity is essential for productive infection and

  4. Impact of sludge flocs on membrane fouling in membrane bioreactors

    DEFF Research Database (Denmark)

    Christensen, Morten Lykkegaard; Niessen, Wolfgang; Jørgensen, Mads Koustrup

    Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control. Large variation in filtration properties measured as flux decline was observed for the different types of sludges....... Further, the flux could partly be reestablished after the relaxation period depending on the sludge composition. The results underline that sludge properties are important for membrane fouling and that control of floc properties, as determined by the composition of the microbial communities...... and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR. High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration...

  5. Membrane Fusion Involved in Neurotransmission: Glimpse from Electron Microscope and Molecular Simulation

    Directory of Open Access Journals (Sweden)

    Zhiwei Yang

    2017-06-01

    Full Text Available Membrane fusion is one of the most fundamental physiological processes in eukaryotes for triggering the fusion of lipid and content, as well as the neurotransmission. However, the architecture features of neurotransmitter release machinery and interdependent mechanism of synaptic membrane fusion have not been extensively studied. This review article expounds the neuronal membrane fusion processes, discusses the fundamental steps in all fusion reactions (membrane aggregation, membrane association, lipid rearrangement and lipid and content mixing and the probable mechanism coupling to the delivery of neurotransmitters. Subsequently, this work summarizes the research on the fusion process in synaptic transmission, using electron microscopy (EM and molecular simulation approaches. Finally, we propose the future outlook for more exciting applications of membrane fusion involved in synaptic transmission, with the aid of stochastic optical reconstruction microscopy (STORM, cryo-EM (cryo-EM, and molecular simulations.

  6. Membrane Fusion Involved in Neurotransmission: Glimpse from Electron Microscope and Molecular Simulation

    Science.gov (United States)

    Yang, Zhiwei; Gou, Lu; Chen, Shuyu; Li, Na; Zhang, Shengli; Zhang, Lei

    2017-01-01

    Membrane fusion is one of the most fundamental physiological processes in eukaryotes for triggering the fusion of lipid and content, as well as the neurotransmission. However, the architecture features of neurotransmitter release machinery and interdependent mechanism of synaptic membrane fusion have not been extensively studied. This review article expounds the neuronal membrane fusion processes, discusses the fundamental steps in all fusion reactions (membrane aggregation, membrane association, lipid rearrangement and lipid and content mixing) and the probable mechanism coupling to the delivery of neurotransmitters. Subsequently, this work summarizes the research on the fusion process in synaptic transmission, using electron microscopy (EM) and molecular simulation approaches. Finally, we propose the future outlook for more exciting applications of membrane fusion involved in synaptic transmission, with the aid of stochastic optical reconstruction microscopy (STORM), cryo-EM (cryo-EM), and molecular simulations. PMID:28638320

  7. The influence of oscillating electromagnetic fields on membrane structure and function: Synthetic liposome and natural membrane bilayer systems with direct application to the controlled delivery of chemical agents

    International Nuclear Information System (INIS)

    Liburdy, R.P.; de Manincor, D.; Fingado, B.

    1989-09-01

    Investigations have been conducted to determine if an imposed electromagnetic field can influence membrane transport, and ion and drug permeability in both synthetic and natural cell membrane systems. Microwave fields enhance accumulation of sodium in the lymphocyte and induce protein shedding at Tc. Microwaves also trigger membrane permeability of liposome systems under specific field exposure conditions. Sensitivity varies in a defined way in bilayers displaying a membrane structural phase transition temperature, Tc; maximal release was observed at or near Tc. Significantly, liposome systems without a membrane phase transition were also found to experience permeability increases but, in contrast, this response was temperature independent. The above results indicate that field-enhanced drug release occurs in liposome vesicles that possess a Tc as well as non-Tc liposomes. Additional studies extend non-Tc liposome responses to the in vivo case in which microwaves trigger Gentamicin release from a liposome ''depot'' placed subcutaneously in the rat hind leg. In addition, evidence is provided that cell surface sequestered liposomes can be triggered by microwave fields to release drugs directly into target cells. 24 refs., 6 figs

  8. Antibacterial and anti-adhesion effects of the silver nanoparticles-loaded poly(L-lactide) fibrous membrane

    International Nuclear Information System (INIS)

    Liu, Shen; Zhao, Jingwen; Ruan, Hongjiang; Wang, Wei; Wu, Tianyi; Cui, Wenguo; Fan, Cunyi

    2013-01-01

    The complications of tendon injury are frequently compromised by peritendinous adhesions and tendon sheath infection. Physical barriers for anti-adhesion may increase the incidence of postoperative infection. This study was designed to evaluate the potential of silver nanoparticles (AgNPs)-loaded poly(L-lactide) (PLLA) electrospun fibrous membranes to prevent adhesion formation and infection. Results of an in vitro drug release study showed that a burst release was followed by sustained release from electrospun fibrous membranes with a high initial silver content. Fewer fibroblasts adhered to and proliferated on the AgNP-loaded PLLA electrospun fibrous membranes compared with pure PLLA electrospun fibrous membrane. In the antibacterial test, the AgNP-loaded PLLA electrospun fibrous membranes can prevent the adhesion of Gram-positive Staphylococcus aureus and Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa. Taken together, these results demonstrate that AgNP-loaded PLLA electrospun fibrous membranes have the convenient practical medical potential of reduction of infection and adhesion formation after tendon injury. - Highlights: ► Silver nanoparticles are directly electrospun into PLLA fibrous membrane. ► Long-lasting release of Ag + ions is achieved. ► Cytotoxicity of silver ions benefits the anti-proliferation of physical barriers. ► Broad anti-microbial effect of drug-loaded fibrous membrane is revealed. ► Antibacterial and anti-adhesion effects of the physical barriers are combined

  9. Interactions of Model Cell Membranes with Nanoparticles

    Science.gov (United States)

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

    2011-12-01

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

  10. Pulse radiolysis studies of model membranes

    International Nuclear Information System (INIS)

    Heijman, M.G.J.

    1984-01-01

    In this thesis the influence of the structure of membranes on the processes in cell membranes were examined. Different models of the membranes were evaluated. Pulse radiolysis was used as the technique to examine the membranes. (R.B.)

  11. Identification and characterization of polyphosphoinositides in the tonoplast membrane

    International Nuclear Information System (INIS)

    Cho, Myeon; Memon, A.R.; Boss, W.F.

    1989-01-01

    In vitro data indicate that the tonoplast membrane is the major target site for IP 3 action and Ca +2 is released from this compartment. If this is true, then several questions arise: (1) Is the plasma membrane or tonoplast the source of IP 3 ? (2) If the plasma membrane is the source of IP 3 , how does IP 3 get to the vacuole? In this connection, the results from in vivo labeling of carrot cells with [ 3 H] inositol show that the major phospholipid components in the tonoplast are PI and lysoPIP. In vitro phosphorylation studies using [γ- 32 P]ATP indicate that PI kinase is present in the tonoplast membrane even though PIP was not detected with inositol labeling. If PIP and PIP 2 are not present in the tonoplast, then IP 3 must diffuse or be transported from the plasma membrane. Since IP 3 is rapidly metabolized by cytosolic phosphatases there may be an IP 3 -sensitive calcium store other than the vacuole closely associated with the plasma membrane

  12. Dynamics of silver elution from functionalised antimicrobial nanofiltration membranes.

    Science.gov (United States)

    Choudhari, S; Habimana, O; Hannon, J; Allen, A; Cummins, E; Casey, E

    2017-07-01

    In an effort to mitigate biofouling on thin film composite membranes such as nanofiltration and reverse osmosis, a myriad of different surface modification strategies has been published. The use of silver nanoparticles (Ag-NPs) has emerged as being particularly promising. Nevertheless, the stability of these surface modifications is still poorly understood, particularly under permeate flux conditions. Leaching or elution of Ag-NPs from the membrane surface can not only affect the antimicrobial characteristics of the membrane, but could also potentially present an environmental liability when applied in industrial-scale systems. This study sought to investigate the dynamics of silver elution and the bactericidal effect of an Ag-NP functionalised NF270 membrane. Inductively coupled plasma-atomic emission spectroscopy was used to show that the bulk of leached silver occurred at the start of experimental runs, and was found to be independent of salt or permeate conditions used. Cumulative amounts of leached silver did, however, stabilise following the initial release, and were shown to have maintained the biocidal characteristics of the modified membrane, as observed by a higher fraction of structurally damaged Pseudomonas fluorescens cells. These results highlight the need to comprehensively assess the time-dependent nature of bactericidal membranes.

  13. Membrane microparticles and diseases.

    Science.gov (United States)

    Wu, Z-H; Ji, C-L; Li, H; Qiu, G-X; Gao, C-J; Weng, X-S

    2013-09-01

    Membrane microparticles (MPs) are plasma membrane-derived vesicles shed by various types of activated or apoptotic cells including platelets, monocytes, endothelial cells, red blood cells, and granulocytes. MPs are being increasingly recognized as important regulators of cell-to-cell interactions. Recent evidences suggest they may play important functions not only in homeostasis but also in the pathogenesis of a number of diseases such as vascular diseases, cancer, infectious diseases and diabetes mellitus. Accordingly, inhibiting the production of MPs may serve as a novel therapeutic strategy for these diseases. Here we review recent advances on the mechanism underlying the generation of MPs and the role of MPs in vascular diseases, cancer, diabetes, inflammation, and pathogen infection.

  14. Physics of smectic membranes

    Science.gov (United States)

    Pieranski, P.; Beliard, L.; Tournellec, J.-Ph.; Leoncini, X.; Furtlehner, C.; Dumoulin, H.; Riou, E.; Jouvin, B.; Fénerol, J.-P.; Palaric, Ph.; Heuving, J.; Cartier, B.; Kraus, I.

    1993-03-01

    Due to their layered structure, smectic liquid crystals can form membranes, similar to soap bubbles, that can be spanned on frames. Such smectic membranes have been used extensively as samples in many structural X-ray studies of smectic liquid crystals. In this context they have been considered as very convenient and highly perfect samples but little attention has been paid to the reasons for their existence and to the process of their formation. Our aim here is to address a first list of questions, which are the most urgent to answer. We will also describe experiments and models that have been conceived especially in order to understand the physics of these fascinating systems.

  15. Radiation effects on cell membranes

    International Nuclear Information System (INIS)

    Koeteles, G.J.

    1982-01-01

    The recent developments in the field of membrane biology of eukaryotic cells result in revival of relevant radiobiological studies. The spatial relations and chemical nature of membrane components provide rather sensitive targets. Experimental data are presented concerning the effects of relatively low doses of X-irradiation and low concentration of tritiated water (HTO) on various receptor functions - concanavalin A, cationized ferritin, poliovirus - of plasma membranes of animal and human cells which point to early and temporary disturbances of the composite structures and functions of membranes. References are given to the multifold roles of radiationinduced membrane phenomena on the development and regeneration of radiation injuries. (orig.)

  16. Radiation effects on cell membranes

    Energy Technology Data Exchange (ETDEWEB)

    Koeteles, G.J.

    1982-11-01

    The recent developments in the field of membrane biology of eukaryotic cells result in revival of relevant radiobiological studies. The spatial relations and chemical nature of membrane components provide rather sensitive targets. Experimental data are presented concerning the effects of relatively low doses of X-irradiation and low concentration of tritiated water (HTO) on various receptor functions - concanavalin A, cationized ferritin, poliovirus - of plasma membranes of animal and human cells which point to early and temporary disturbances of the composite structures and functions of membranes. References are given to the multifold roles of radiationinduced membrane phenomena on the development and regeneration of radiation injuries.

  17. Choroidal neovascular membrane

    OpenAIRE

    Bhatt Nitul; Diamond James; Jalali Subhadra; Das Taraprasad

    1998-01-01

    Choroidal neovascular membrane in the macular area is one of the leading causes of severe visual loss. Usually a manifestation in elderly population, it is often associated with age-related macular degeneration. The current mainstay of management is early diagnosis, usually by fundus examination, aided by angiography and photocoagulation in selected cases. Various other modalities of treatment including surgery are being considered as alternate options, but with limited success. The purpose o...

  18. Generalized chiral membrane dynamics

    International Nuclear Information System (INIS)

    Cordero, R.; Rojas, E.

    2003-01-01

    We develop the dynamics of the chiral superconducting membranes (with null current) in an alternative geometrical approach. Besides of this, we show the equivalence of the resulting description with the one known Dirac-Nambu-Goto (DNG) case. Integrability for chiral string model is obtained using a proposed light-cone gauge. In a similar way, domain walls are integrated by means of a simple Ansatz. (Author)

  19. Membrane Stability Testing

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1997-09-30

    The Electrosynthesis Co. Inc. (ESC) was contracted by the Westinghouse Savannah River Company to investigate the long term performance and durability of cell components (anode, membrane, cathode) in an electrochemical caustic recovery process using a simulated SRC liquid waste as anolyte solution. This report details the results of two long-term studies conducted using an ICI FM01 flow cell. This cell is designed and has previously been demonstrated to scale up directly into the commercial scale ICI FM21 cell.

  20. Membrane technology applications

    Energy Technology Data Exchange (ETDEWEB)

    Golomb, A

    1990-10-01

    Due to a continuing emphasis on increasing the efficiency of utilizing the Province's electrical energy system, a Membrane Testing and Development Facility (MTDF) has been established at Ontario Hydro Research Division. The MTDF comprises bench-scale and pilot-scale reverse osmosis (RO) and ultrafiltration (UF) systems. RO and UF are membrane separation technologies which with microfiltration (MF) have found numerous industrial applications in wastewater treatment and/or byproduct recovery. Since no phase change is involved in RO and UF, they are more energy efficient separation processes than, say, evaporation or distillation. Initial tests have been carried out to demonstrate the capability of the newly-established MTDF. Bench- and pilot-scale RO treatment, at 4.1 MPa applied pressure, of a simulated nickel plating waste rinse stream was demonstrated. RO membrane rejection efficiencies for nickel were 99+% (in the bench scale test) and 99.9+% (on the pilot scale). Volume reduction factors of about 25 were attained, at purified water flux rates in the range 1 to 1.5 m{sup 3}/m{sup 2} per day. Good correlation was noted between bench-scale and pilot-scale RO test results. Pilot-scale UF of a simulated industrial cutting oil/water waste emulsion at 0.40 MPa gave 99+% oil rejection (pilot scale) at a flux rate of 0.7 m{sup 3}/m{sup 2} per day. A volume reduction of about 5.2 was attained. Overviews of opportunities for membrane separation technology applied to the metal cutting and surface finishing industries, and the food and beverage industry are given. Capabilities (and some present needs) of the MTDF are outlined, with recommendations. 17 refs., 10 figs., 7 tabs.

  1. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  2. A new concept in polymeric thin-film composite nanofiltration membranes with antibacterial properties.

    Science.gov (United States)

    Mollahosseini, Arash; Rahimpour, Ahmad

    2013-01-01

    A new, thin film, biofouling resistant, nanofiltration (NF) membrane was fabricated with two key characteristics, viz. a low rate of silver (Ag) release and long-lasting antibacterial properties. In the new approach, nanoparticles were embedded completely in a polymeric thin-film layer. A comparison was made between the new thin-film composite (TFC), NF membrane and thin-film nanocomposite (TFN), and antibacterial NF membranes. Both types of NF membrane were fabricated by interfacial polymerization on a polysulphone sublayer using m-phenylenediamine and trimesoyl chloride as an amine monomer and an acid chloride monomer, respectively. Energy dispersive X-ray (EDX) microanalysis demonstrated the presence of Ag nanoparticles. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the cross-sectional and surface morphological properties of the NF membranes. Permeability and salt rejection were tested using a dead-end filtration cell. Ag leaching from the membranes was measured using inductively coupled mass spectrometry (ICP-MS). Morphological studies showed that the TFC NF membranes had better thin-film formation (a more compact structure and a smoother surface) than TFN NF membranes. Performance experiments on TFC NF membranes revealed that permeability was good, without sacrificing salt rejection. The antibacterial properties of the fabricated membranes were tested using the disk diffusion method and viable plate counts. The antibiofouling properties of the membranes were examined by measuring the quantity of bacterial cells released from the biofilm formed (as a function of the amount of biofilm present). A more sensitive surface was observed compared to that of a typical antibacterial NF membrane. The Ag leaching rates were low, which will likely result in long-lasting antibacterial and biofouling resistant properties.

  3. Neutrons and model membranes

    Science.gov (United States)

    Fragneto, G.

    2012-11-01

    Current research in membrane protein biophysics highlights the emerging role of lipids in shaping membrane protein function. Cells and organisms have developed sophisticated mechanisms for controlling the lipid composition and many diseases are related to the failure of these mechanisms. One of the recent advances in the field is the discovery of the existence of coexisting micro-domains within a single membrane, important for regulating some signaling pathways. Many important properties of these domains remain poorly characterized. The characterization and analysis of bio-interfaces represent a challenge. Performing measurements on these few nanometer thick, soft, visco-elastic and dynamic systems is close to the limits of the available tools and methods. Neutron scattering techniques including small angle scattering, diffraction, reflectometry as well as inelastic methods are rapidly developing for these studies and are attracting an increasing number of biologists and biophysicists at large facilities. This manuscript will review some recent progress in the field and provide perspectives for future developments. It aims at highlighting neutron reflectometry as a versatile method to tackle questions dealing with the understanding and function of biomembranes and their components. The other important scattering methods are only briefly introduced.

  4. Viral membrane fusion

    International Nuclear Information System (INIS)

    Harrison, Stephen C.

    2015-01-01

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. - Highlights: • Viral fusion proteins overcome the high energy barrier to lipid bilayer merger. • Different molecular structures but the same catalytic mechanism. • Review describes properties of three known fusion-protein structural classes. • Single-virion fusion experiments elucidate mechanism

  5. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  6. Quantum charged rigid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, Ruben [Departamento de Fisica, Escuela Superior de Fisica y Matematicas del I.P.N., Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, D.F. (Mexico); Molgado, Alberto [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Zacatecas Zac. (Mexico); Rojas, Efrain, E-mail: cordero@esfm.ipn.mx, E-mail: amolgado@fisica.uaz.edu.mx, E-mail: efrojas@uv.mx [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)

    2011-03-21

    The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.

  7. Quantum charged rigid membrane

    International Nuclear Information System (INIS)

    Cordero, Ruben; Molgado, Alberto; Rojas, Efrain

    2011-01-01

    The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.

  8. Viral membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Stephen C., E-mail: harrison@crystal.harvard.edu

    2015-05-15

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. - Highlights: • Viral fusion proteins overcome the high energy barrier to lipid bilayer merger. • Different molecular structures but the same catalytic mechanism. • Review describes properties of three known fusion-protein structural classes. • Single-virion fusion experiments elucidate mechanism.

  9. Released radioactivity reducing facility

    International Nuclear Information System (INIS)

    Tanaka, Takeaki.

    1992-01-01

    Upon occurrence of a reactor accident, penetration portions of a reactor container, as a main leakage source from a reactor container, are surrounded by a plurality of gas-tight chambers, the outside of which is surrounded by highly gas-tightly buildings. Branched pipelines of an emergency gas processing system are introduced to each of the gas-tight chambers and they are joined and in communication with an emergency gas processing device. With such a constitution, radioactive materials are prevented from leaking directly from the buildings. Further, pipeline openings of the emergency gas processing facility are disposed in the plurality highly gas-tight penetration chambers. If the radioactive materials are leaked from the reactor to elevate the pressure in the penetration chambers, the radioactive materials are introduced to a filter device in the emergency gas processing facility by way of the branched pipelines, filtered and then released to the atmosphere. Accordingly, the reliability and safety of the system can be improved. (T.M.)

  10. Containment and release management

    International Nuclear Information System (INIS)

    Lehner, J.R.; Pratt, W.T.

    1988-01-01

    Reducing the risk from potentially severe accidents by appropriate accident management strategies is receiving increased attention from the international reactor safety community. Considerable uncertainty still surrounds some of the physical phenomena likely to occur during a severe accident. The USNRC, in developing its research plan for accident management, wants to ensure that both the developers and implementers of accident management strategies are aware of the uncertainty associated with the plant operators' ability to correctly diagnose an accident, as well as the uncertainties associated with various preventive and mitigative strategies. The use of a particular accident management strategy can have both positive and negative effects on the status of a plant and these effects must be carefully weighed before a particular course of action is chosen and implemented. By using examples of severe accident scenarios, initial insights are presented here regarding the indications plant operators may have to alert them to particular accident states. Insights are also offered on the various management actions operators and plant technical staff might pursue for particular accident situations and the pros and cons associated with such actions. The examples given are taken for the most part from the containment and release phase of accident management, since this is the current focus of the effort in the accident management area at Brookhaven National Laboratory. 2 refs

  11. Released radioactivity reducing device

    International Nuclear Information System (INIS)

    Miyamoto, Yumi.

    1995-01-01

    A water scrubber is disposed in a scrubber tank and a stainless steel fiber filter is disposed above the water scrubber. The upper end of the scrubber tank is connected by way of a second bent tube to a capturing vessel incorporating a moisture removing layer and an activated carbon filter. The exit of the capturing vessel is connected to a stack. Upon occurrence of an accident of a BWR-type power plant, gases containing radioactive materials released from a reactor container are discharged into the water scrubber from a first bent tube through a venturi tube nozzle, and water soluble and aerosol-like radioactive materials are captured in the water. Aerosol and splashes of water droplets which can not be captured thoroughly by the water scrubber are captured by the stainless steel fiber filter. Gases passing through the scrubber tank are introduced to a capturing vessel through a second bent tube, and organic iodine is captured by the activated carbon filter. (I.N.)

  12. COMMERCIAL SNF ACCIDENT RELEASE FRACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    S.O. Bader

    1999-10-18

    The purpose of this design analysis is to specify and document the total and respirable fractions for radioactive materials that are released from an accident event at the Monitored Geologic Repository (MGR) involving commercial spent nuclear fuel (CSNF) in a dry environment. The total and respirable release fractions will be used to support the preclosure licensing basis for the MGR. The total release fraction is defined as the fraction of total CSNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. The radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses. This subset of the total release fraction is referred to as the respirable release fraction. Potential accidents may involve waste forms that are characterized as either bare (unconfined) fuel assemblies or confined fuel assemblies. The confined CSNF assemblies at the MGR are contained in shipping casks, canisters, or disposal containers (waste packages). In contrast to the bare fuel assemblies, the container that confines the fuel assemblies has the potential of providing an additional barrier for diminishing the total release fraction should the fuel rod cladding breach during an accident. However, this analysis will not take credit for this additional bamer and will establish only the total release fractions for bare unconfined CSNF assemblies, which may however be

  13. COMMERCIAL SNF ACCIDENT RELEASE FRACTIONS

    International Nuclear Information System (INIS)

    S.O. Bader

    1999-01-01

    The purpose of this design analysis is to specify and document the total and respirable fractions for radioactive materials that are released from an accident event at the Monitored Geologic Repository (MGR) involving commercial spent nuclear fuel (CSNF) in a dry environment. The total and respirable release fractions will be used to support the preclosure licensing basis for the MGR. The total release fraction is defined as the fraction of total CSNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. The radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses. This subset of the total release fraction is referred to as the respirable release fraction. Potential accidents may involve waste forms that are characterized as either bare (unconfined) fuel assemblies or confined fuel assemblies. The confined CSNF assemblies at the MGR are contained in shipping casks, canisters, or disposal containers (waste packages). In contrast to the bare fuel assemblies, the container that confines the fuel assemblies has the potential of providing an additional barrier for diminishing the total release fraction should the fuel rod cladding breach during an accident. However, this analysis will not take credit for this additional bamer and will establish only the total release fractions for bare unconfined CSNF assemblies, which may however be

  14. Parallel artificial liquid membrane extraction

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Rasmussen, Knut Einar; Parmer, Marthe Petrine

    2013-01-01

    This paper reports development of a new approach towards analytical liquid-liquid-liquid membrane extraction termed parallel artificial liquid membrane extraction. A donor plate and acceptor plate create a sandwich, in which each sample (human plasma) and acceptor solution is separated by an arti......This paper reports development of a new approach towards analytical liquid-liquid-liquid membrane extraction termed parallel artificial liquid membrane extraction. A donor plate and acceptor plate create a sandwich, in which each sample (human plasma) and acceptor solution is separated...... by an artificial liquid membrane. Parallel artificial liquid membrane extraction is a modification of hollow-fiber liquid-phase microextraction, where the hollow fibers are replaced by flat membranes in a 96-well plate format....

  15. Solid-state membrane module

    Science.gov (United States)

    Gordon, John Howard [Salt Lake City, UT; Taylor, Dale M [Murray, UT

    2011-06-07

    Solid-state membrane modules comprising at least one membrane unit, where the membrane unit has a dense mixed conducting oxide layer, and at least one conduit or manifold wherein the conduit or manifold comprises a dense layer and at least one of a porous layer and a slotted layer contiguous with the dense layer. The solid-state membrane modules may be used to carry out a variety of processes including the separating of any ionizable component from a feedstream wherein such ionizable component is capable of being transported through a dense mixed conducting oxide layer of the membrane units making up the membrane modules. For ease of construction, the membrane units may be planar.

  16. Underground water stress release models

    Science.gov (United States)

    Li, Yong; Dang, Shenjun; Lü, Shaochuan

    2011-08-01

    The accumulation of tectonic stress may cause earthquakes at some epochs. However, in most cases, it leads to crustal deformations. Underground water level is a sensitive indication of the crustal deformations. We incorporate the information of the underground water level into the stress release models (SRM), and obtain the underground water stress release model (USRM). We apply USRM to the earthquakes occurred at Tangshan region. The analysis shows that the underground water stress release model outperforms both Poisson model and stress release model. Monte Carlo simulation shows that the simulated seismicity by USRM is very close to the real seismicity.

  17. Flux Enhancement in Membrane Distillation Using Nanofiber Membranes

    Directory of Open Access Journals (Sweden)

    T. Jiříček

    2016-01-01

    Full Text Available Membrane distillation (MD is an emerging separation technology, whose largest application potential lies in the desalination of highly concentrated solutions, which are out of the scope of reverse osmosis. Despite many attractive features, this technology is still awaiting large industrial application. The main reason is the lack of commercially available membranes with fluxes comparable to reverse osmosis. MD is a thermal separation process driven by a partial vapour pressure difference. Flux, distillate purity, and thermal efficiency are always in conflict, all three being strictly connected with pore size, membrane hydrophobicity, and thickness. The world has not seen the ideal membrane yet, but nanofibers may offer a solution to these contradictory requirements. Membranes of electrospun PVDF were tested under various conditions on a direct contact (DCMD unit, in order to determine the optimum conditions for maximum flux. In addition, their performance was compared to commonly available PTFE, PE, and PES membranes. It was confirmed that thinner membranes have higher fluxes and a lower distillate purity and also higher energy losses via conduction across the membrane. As both mass and heat transfer are connected, it is best to develop new membranes with a target application in mind, for the specific membrane module and operational conditions.

  18. Flash release an alternative for releasing complex MEMS devices

    NARCIS (Netherlands)

    Deladi, S.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

    2004-01-01

    A novel time-saving and cost-effective release technique has been developed and is described. The physical nature of the process is explained in combination with experimental observations. The results of the flash release process are compared with those of freeze-drying and supercritical CO2

  19. Separation of tritiated water using graphene oxide membrane

    Energy Technology Data Exchange (ETDEWEB)

    Sevigny, Gary J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Motkuri, Radha K. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Gotthold, David W. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Fifield, Leonard S. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Frost, Anthony P. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Bratton, Wesley [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

    2015-06-28

    In future nuclear fuel reprocessing plants and possibly for nuclear power plants, the cleanup of tritiated water will be needed for hundreds of thousands of gallons of water with low activities of tritium. This cleanup concept utilizes graphene oxide laminar membranes (GOx) for the separation of low-concentration (10-3-10 µCi/g) tritiated water to create water that can be released to the environment and a much smaller waste stream with higher tritium concentrations. Graphene oxide membranes consist of hierarchically stacked, overlapping molecular layers and represent a new class of materials. A permeation rate test was performed with a 2-µm-thick cast Asbury membrane using mixed gas permeability testing with zero air (highly purified atmosphere) and with air humidified with either H2O or D2O to a nominal 50% relative humidity. The membrane permeability for both H2O and D2O was high with N2 and O2 at the system measurement limit. The membrane water permeation rate was compared to a Nafion® membrane and the GOx permeation was approximately twice as high at room temperature. The H2O vapor permeation rate was 5.9 × 102 cc/m2/min (1.2 × 10-6 g/min-cm2), which is typical for graphene oxide membranes. To demonstrate the feasibility of such isotopic water separation through GOX laminar membranes, an experimental setup was constructed to use pressure-driven separation by heating the isotopic water mixture at one side of the membrane to create steam while cooling the other side. Several membranes were tested and were prepared using different starting materials and by different pretreatment methods. The average separation result was 0.8 for deuterium and 0.6 for tritium. Higher or lower temperatures may also improve separation efficiency but neither has been tested yet. A rough estimate of cost compared to current technology was also included as an indication of potential viability of the process. The relative process costs were based on the rough size of facility to

  20. Membrane junctions in Xenopus eggs: their distribution suggests a role in calcium regulation.

    Science.gov (United States)

    Gardiner, D M; Grey, R D

    1983-04-01

    We have observed the presence of membrane junctions formed between the plasma membrane and cortical endoplasmic reticulum of mature, unactivated eggs of xenopus laevis. The parallel, paired membranes of the junction are separated by a 10-mn gap within which electron-dense material is present. This material occurs in patches with an average center-to-center distance of approximately 30 nm. These junctions are rare in immature (but fully grown) oocytes (approximately 2 percent of the plasma membrane is associated with junctions) and increase dramatically during progesterone-induced maturation. Junctions in the mature, unactivated egg are two to three times more abundant in the animal hemisphere (25-30 percent of the plasma membrane associated with junction) as compared with the vegetal hemisphere (10-15 percent). Junction density decreases rapidly to values characteristic of immature oocytes in response to egg activation. The plasma membrane-ER junctions of xenopus eggs are strikingly similar in structure to membrane junctions in muscle cells thought to be essential in the triggering of intracellular calcium release from the sarcoplasmic reticulum. In addition, the junctions' distinctive, animal-vegetal polarity of distribution, their dramatic appearance during maturation, and their disapperance during activation are correlated with previously documented patterns of calcium-mediated events in anuran eggs. We discuss several lines of evidence supporting the hypothesis that these junctions in xenopus eggs are sites that transduce extracellular events into intracellular calcium release during fertilization and activation of development.

  1. Ultraviolet- and sunlight-induced lipid peroxidation in liposomal membrane

    International Nuclear Information System (INIS)

    Mandal, T.K.; Chatterjee, S.N.

    1980-01-01

    Ultraviolet radiation and sunlight caused lipid peroxidation in the liposomal membrane (as detected by measurement of the oxidation index, A 233 /A 215 , and the amount of malondialdehyde formed) and made the membrane leaky (as revealed by the release of the trapped chromate anions). The oxidation index and the formation of malondialdehyde increased linearly with increasing dose of radiation and depended significantly on the dose rate. The effects were smaller in liposomes derived from Vibrio cholerae phospholipid than in those derived from egg lecithin. The effects of the radiation dose and dose rate on hemolysis and peroxidation (MDA formation) of the erythrocyte membrane followed a similar pattern. A direct correlation between the percentage leakage of chromate (Y) and the oxidation index (X) of the liposomal system was obtained as Y = 236.5 x X

  2. Use of rhamnolipid biosurfactant for membrane biofouling prevention and cleaning.

    Science.gov (United States)

    Kim, Lan Hee; Jung, Yongmoon; Kim, Sung-Jo; Kim, Chang-Min; Yu, Hye-Weon; Park, Hee-Deung; Kim, In S

    2015-01-01

    Rhamnolipids were evaluated as biofouling reducing agents in this study. The permeability of the bacterial outer membrane was increased by rhamnolipids while the growth rate of Pseudomonas aeruginosa was not affected. The surface hydrophobicity was increased through the release of lipopolysaccharides and extracellular polymeric substances from the outer cell membrane. Rhamnolipids were evaluated as agents for the prevention and cleaning of biofilms. A high degree of biofilm detachment was observed when the rhamnolipids were used as a cleaning agent. In addition, effective biofilm reduction occurred when rhamnolipids were applied to various species of Gram-negative bacteria isolated from seawater samples. Biofilm reduction using rhamnolipids was comparable to commercially available surfactants. In addition, 20% of the water flux was increased after rhamnolipid treatment (300 μg ml(-1), 6 h exposure time) in a dead-end filtration system. Rhamnolipids appear to have promise as biological agents for reducing membrane biofouling.

  3. Herpesvirus glycoproteins undergo multiple antigenic changes before membrane fusion.

    Directory of Open Access Journals (Sweden)

    Daniel L Glauser

    Full Text Available Herpesvirus entry is a complicated process involving multiple virion glycoproteins and culminating in membrane fusion. Glycoprotein conformation changes are likely to play key roles. Studies of recombinant glycoproteins have revealed some structural features of the virion fusion machinery. However, how the virion glycoproteins change during infection remains unclear. Here using conformation-specific monoclonal antibodies we show in situ that each component of the Murid Herpesvirus-4 (MuHV-4 entry machinery--gB, gH/gL and gp150--changes in antigenicity before tegument protein release begins. Further changes then occurred upon actual membrane fusion. Thus virions revealed their final fusogenic form only in late endosomes. The substantial antigenic differences between this form and that of extracellular virions suggested that antibodies have only a limited opportunity to block virion membrane fusion.

  4. Metabolism of phosphatidylinositol in plasma membranes and synaptosomes of rat cerebral cortex: A comparison between endogenous vs exogenous substrate pools

    International Nuclear Information System (INIS)

    Navidi, M.; MacQuarrie, R.A.; Sun, G.Y.

    1990-01-01

    The metabolism of phosphatidylinositols (PI) labeled with [14C]arachidonic acid within plasma membranes or synaptosomes was compared to the metabolism of PI prelabeled with [14C]arachidonic acid and added exogenously to the same membranes. Incubation of membranes containing the endogenously-labeled PI pool in the presence of Ca2+ resulted in the release of labeled arachidonic acid, as well as a small amount of labeled diacylglycerol. Labeled arachidonic acid was effectively reutilized and returned to the membrane phospholipids in the presence of adenosine triphosphate (ATP), CoA, and lysoPI. Although Ca2+ promoted the release of labeled diacylglycerol from prelabeled plasma membranes, this amount was only 17% of the maximal release, i.e., release in the presence of deoxycholate and Ca2+. This latter condition is known to fully activate the PI-phospholipase C, and incubation of prelabeled plasma membranes resulted in a six-fold increase in labeled diacylglycerols. On the other hand, when exogenously labeled PI were incubated with plasma membranes in the presence of Ca2+, the labeled diacylglycerols released were 59% of that compared to the fully activated condition. The phospholipase C action was calcium-dependent, regardless of whether exogenous or endogenous substrates were used in the incubation. In contrast to plasma membranes, intact synaptosomes had limited ability to metabolize exogenous PI even in the presence of Ca2+, although the activity of phospholipase C was similar to that in the plasma membranes when assayed in the presence of deoxycholate and Ca2+. These results suggest that discrete pools of PI are present in plasma membranes, and that the pool associated with the acyltransferase is apparently not readily accessible to hydrolysis by phospholipase C

  5. Characterization of taurine binding, uptake, and release in the rat hypothalamus

    International Nuclear Information System (INIS)

    Hanretta, A.T.

    1985-01-01

    The neurotransmitter criteria of specific receptors, inactivation, and release were experimentally examined for taurine in the hypothalamus. Specific membrane binding and synaptosomal uptake of taurine both displayed high affinity and low affinity systems. The neurotransmitter criterion of release was studied in superfused synaptosomes. Exposure of synaptosomes which had been preloaded with a concentration of [ 3 H]taurine in the high affinity uptake range (1.5 μM) to either 56 mM K + or 100 μM veratridine evoked a Ca 2+ -independent release. Exposure of synaptosomes which had been preloaded with a concentration of [ 3 H]taurine in the low affinity uptake range (2 mM) to 56 mM K + induced a Ca 2+ -independent release, whereas 100 + M veratridine did not, either in the presence or absence of Ca 2+ . Based on these results, as well as other observations, a model is proposed in which the high affinity uptake system is located on neuronal membranes and the low affinity uptake system is located on glial membranes. The mechanisms of binding, uptake, and release in relation to the cellular location of each are discussed. We conclude that the neurotransmitter criterion of activation by re-uptake is satisfied for taurine in the hypothalamus. However, the failure to demonstrate both a specific taurine receptor site and a Ca 2+ -dependent evoked release, necessitates that we conclude that taurine appears not to function as a hypothalamic neurotransmitter, at least not in the classical sense

  6. Extracellular vesicles as a platform for membrane-associated therapeutic protein delivery.

    Science.gov (United States)

    Yang, Yoosoo; Hong, Yeonsun; Cho, Eunji; Kim, Gi Beom; Kim, In-San

    2018-01-01

    Membrane proteins are of great research interest, particularly because they are rich in targets for therapeutic application. The suitability of various membrane proteins as targets for therapeutic formulations, such as drugs or antibodies, has been studied in preclinical and clinical studies. For therapeutic application, however, a protein must be expressed and purified in as close to its native conformation as possible. This has proven difficult for membrane proteins, as their native conformation requires the association with an appropriate cellular membrane. One solution to this problem is to use extracellular vesicles as a display platform. Exosomes and microvesicles are membranous extracellular vesicles that are released from most cells. Their membranes may provide a favourable microenvironment for membrane proteins to take on their proper conformation, activity, and membrane distribution; moreover, membrane proteins can cluster into microdomains on the surface of extracellular vesicles following their biogenesis. In this review, we survey the state-of-the-art of extracellular vesicle (exosome and small-sized microvesicle)-based therapeutics, evaluate the current biological understanding of these formulations, and forecast the technical advances that will be needed to continue driving the development of membrane protein therapeutics.

  7. Binding and Fusion of Extracellular Vesicles to the Plasma Membrane of Their Cell Targets.

    Science.gov (United States)

    Prada, Ilaria; Meldolesi, Jacopo

    2016-08-09

    Exosomes and ectosomes, extracellular vesicles of two types generated by all cells at multivesicular bodies and the plasma membrane, respectively, play critical roles in physiology and pathology. A key mechanism of their function, analogous for both types of vesicles, is the fusion of their membrane to the plasma membrane of specific target cells, followed by discharge to the cytoplasm of their luminal cargo containing proteins, RNAs, and DNA. Here we summarize the present knowledge about the interactions, binding and fusions of vesicles with the cell plasma membrane. The sequence initiates with dynamic interactions, during which vesicles roll over the plasma membrane, followed by the binding of specific membrane proteins to their cell receptors. Membrane binding is then converted rapidly into fusion by mechanisms analogous to those of retroviruses. Specifically, proteins of the extracellular vesicle membranes are structurally rearranged, and their hydrophobic sequences insert into the target cell plasma membrane which undergoes lipid reorganization, protein restructuring and membrane dimpling. Single fusions are not the only process of vesicle/cell interactions. Upon intracellular reassembly of their luminal cargoes, vesicles can be regenerated, released and fused horizontally to other target cells. Fusions of extracellular vesicles are relevant also for specific therapy processes, now intensely investigated.

  8. Membranes, methods of making membranes, and methods of separating gases using membranes

    Science.gov (United States)

    Ho, W. S. Winston

    2012-10-02

    Membranes, methods of making membranes, and methods of separating gases using membranes are provided. The membranes can include at least one hydrophilic polymer, at least one cross-linking agent, at least one base, and at least one amino compound. The methods of separating gases using membranes can include contacting a gas stream containing at least one of CO.sub.2, H.sub.2S, and HCl with one side of a nonporous and at least one of CO.sub.2, H.sub.2S, and HCl selectively permeable membrane such that at least one of CO.sub.2, H.sub.2S, and HCl is selectively transported through the membrane.

  9. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul; Alsaadi, Ahmad Salem; Francis, Lijo; Livazovic, Sara; Ghaffour, NorEddine; Amy, Gary L.; Nunes, Suzana Pereira

    2013-01-01

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  10. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul

    2013-08-07

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  11. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yoong-Kee [National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba (Japan); Henson, Neil J.; Kim, Yu Seung [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2015-12-31

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.

  12. Cellulose Nanocrystal Membranes as Excipients for Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Ananda M. Barbosa

    2016-12-01

    Full Text Available In this work, cellulose nanocrystals (CNCs were obtained from flax fibers by an acid hydrolysis assisted by sonochemistry in order to reduce reaction times. The cavitation inducted during hydrolysis resulted in CNC with uniform shapes, and thus further pretreatments into the cellulose are not required. The obtained CNC exhibited a homogeneous morphology and high crystallinity, as well as typical values for surface charge. Additionally, CNC membranes were developed from CNC solution to evaluation as a drug delivery system by the incorporation of a model drug. The drug delivery studies were carried out using chlorhexidine (CHX as a drug and the antimicrobial efficiency of the CNC membrane loaded with CHX was examined against Gram-positive bacteria Staphylococcus aureus (S. Aureus. The release of CHX from the CNC membranes is determined by UV-Vis. The obtaining methodology of the membranes proved to be simple, and these early studies showed a potential use in antibiotic drug delivery systems due to the release kinetics and the satisfactory antimicrobial activity.

  13. Effect of Electron-Beam Irradiation on Bacterial Cellulose Membranes Used as Transdermal Drug Delivery Systems

    International Nuclear Information System (INIS)

    Stoica-Guzun, A.

    2006-01-01

    Multiple methods are used to modify material surfaces. Radiation is an effective tool for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. Bacterial cellulose is a promising biomaterial synthesized by Acetobacter xylinum. It has a distinctive ultrafine reticulated structure that may become a perfect matrix as an optimal wound healing environment. In this work, high energy irradiation (γ rays from 137 C s) was applied to modify bacterial cellulose membranes. The effect of varying irradiation doses on membranes permeability was studied. Tetracycline was involved in the study of diffusivity as model drug. Release and permeation of drug from irradiated and non-irradiated membranes were done using a diffusion cell. The membrane permeability was determined using a psudo-steady state analysis based on Fick's law

  14. Sustained release of radioprotective agents

    International Nuclear Information System (INIS)

    Shani, J.

    1980-11-01

    New pharmaceutical formulations for the sustained release into the G.I. tract of radioprotective agents have been developed by the authors. The experimental method initially consisted in the production of methylcellulose microcapsules. This method failed apparently because of the premature ''explosion'' of the microcapsules and the consequent premature release of massive amounts of the drug. A new method has been developed which consists in drying and pulverising cysteamine and cysteine preparations, mixing them in various proportions with stearic acid and ethylcellulose as carriers. The mixture is then compressed into cylindrical tablets at several pressure values and the leaching rate of the radioprotective agents is then measured by spectrophotometry. The relation between the concentration of the active drug and its rate of release, and the effect on the release rate of the pressure applied to the tablet during its formation were also investigated. Results indicating that the release rate was linearly related to the square root of ''t'' seem to be in agreement with what is predictable, according to Higuchi's equation, save for the very initial and terminal phases. A clear correlation was also established between the stearic acid/ethylcellulose ratios and the release of 20% cysteine, namely a marked decrease in the rate of cysteine release was observed with increasing concentrations of stearic acid. Finally, it was observed that a higher formation pressure results in quicker release of the drug

  15. Press Oil Final Release Survey

    Energy Technology Data Exchange (ETDEWEB)

    Whicker, Jeffrey Jay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ruedig, Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-11

    There are forty-eight 55 gallon barrels filled with hydraulic oil that are candidates for release and recycle. This oil needs to be characterized prior to release. Principles of sampling as provided in MARSAME/MARSSIM approaches were used as guidance for sampling.

  16. Workload Control with Continuous Release

    NARCIS (Netherlands)

    Phan, B. S. Nguyen; Land, M. J.; Gaalman, G. J. C.

    2009-01-01

    Workload Control (WLC) is a production planning and control concept which is suitable for the needs of make-to-order job shops. Release decisions based on the workload norms form the core of the concept. This paper develops continuous time WLC release variants and investigates their due date

  17. Amodiaquine polymeric membrane electrode.

    Science.gov (United States)

    Malongo, T Kimbeni; Blankert, B; Kambu, O; Amighi, K; Nsangu, J; Kauffmann, J-M

    2006-04-11

    The construction and electrochemical response characteristics of two types of poly(vinyl chloride) (PVC) membrane sensors for the determination of amodiaquine hydrochloride (ADQ.2HCl) are described. The sensing membrane comprised an ion-pair formed between the cationic drug and sodium tetraphenyl borate (NaTPB) or potassium tetrakis(4-chlorophenyl) borate (KTCPB) in a plasticized PVC matrix. Eight PVC membrane ion-selective electrodes were fabricated and studied. Several plasticizers were studied namely, dioctyl phthalate (DOP), 2-nitrophenyl octyl ether (NPOE), dioctyl phenylphosphonate (DOPP) and bis(2-ethylhexyl)adipate (EHA). The sensors display a fast, stable and near-Nernstian response over a relative wide ADQ concentration range (3.2 x 10(-6) to 2.0 x 10(-2) M), with slopes comprised between 28.5 and 31.4 mV dec(-1) in a pH range comprised between pH 3.7 and 5.5. The assay of amodiaquine hydrochloride in pharmaceutical dosage forms using one of the proposed sensors gave average recoveries of 104.3 and 99.9 with R.S.D. of 0.3 and 0.6% for tablets (Malaritab) and a reconstituted powder containing ADQ.2HCl, respectively. The sensor was also used for dissolution profile studies of two drug formulations. The sensor proved to have a good selectivity for ADQ.2HCl over some inorganic and organic compounds, however, berberine chloride interfered significantly. The results were validated by comparison with a spectrophotometric assay according to the USP pharmacopoeia.

  18. Introducing Membrane Charge and Membrane Potential to T Cell Signaling

    Directory of Open Access Journals (Sweden)

    Yuanqing Ma

    2017-11-01

    Full Text Available While membrane models now include the heterogeneous distribution of lipids, the impact of membrane charges on regulating the association of proteins with the plasma membrane is often overlooked. Charged lipids are asymmetrically distributed between the two leaflets of the plasma membrane, resulting in the inner leaflet being negatively charged and a surface potential that attracts and binds positively charged ions, proteins, and peptide motifs. These interactions not only create a transmembrane potential but they can also facilitate the formation of charged membrane domains. Here, we reference fields outside of immunology in which consequences of membrane charge are better characterized to highlight important mechanisms. We then focus on T cell receptor (TCR signaling, reviewing the evidence that membrane charges and membrane-associated calcium regulate phosphorylation of the TCR–CD3 complex and discuss how the immunological synapse exhibits distinct patterns of membrane charge distribution. We propose that charged lipids, ions in solution, and transient protein interactions form a dynamic equilibrium during T cell activation.

  19. Toxic releases from power plants

    International Nuclear Information System (INIS)

    Rubin, E.S.

    1999-01-01

    Beginning in 1998, electric power plants burning coal or oil must estimate and report their annual releases of toxic chemicals listed in the Toxics Release Inventory (TRI) published by the US Environmental Protection Agency (EPA). This paper identifies the toxic chemicals of greatest significance for the electric utility sector and develops quantitative estimates of the toxic releases reportable to the TRI for a representative coal-fired power plant. Key factors affecting the magnitude and types of toxic releases for individual power plants also are discussed. A national projection suggests that the magnitude of electric utility industry releases will surpass those of the manufacturing industries which current report to the TRI. Risk communication activities at the community level will be essential to interpret and provide context for the new TRI results

  20. Tuning Liposome Membrane Permeability by Competitive Peptide Dimerization and Partitioning-Folding Interactions Regulated by Proteolytic Activity

    Science.gov (United States)

    Lim, Seng Koon; Sandén, Camilla; Selegård, Robert; Liedberg, Bo; Aili, Daniel

    2016-02-01

    Membrane active peptides are of large interest for development of drug delivery vehicles and therapeutics for treatment of multiple drug resistant infections. Lack of specificity can be detrimental and finding routes to tune specificity and activity of membrane active peptides is vital for improving their therapeutic efficacy and minimize harmful side effects. We describe a de novo designed membrane active peptide that partition into lipid membranes only when specifically and covalently anchored to the membrane, resulting in pore-formation. Dimerization with a complementary peptide efficiently inhibits formation of pores. The effect can be regulated by proteolytic digestion of the inhibitory peptide by the matrix metalloproteinase MMP-7, an enzyme upregulated in many malignant tumors. This system thus provides a precise and specific route for tuning the permeability of lipid membranes and a novel strategy for development of recognition based membrane active peptides and indirect enzymatically controlled release of liposomal cargo.

  1. Oxygen Transport Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay

    2008-08-30

    The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

  2. Molecularly Imprinted Membranes

    Science.gov (United States)

    Trotta, Francesco; Biasizzo, Miriam; Caldera, Fabrizio

    2012-01-01

    Although the roots of molecularly imprinted polymers lie in the beginning of 1930s in the past century, they have had an exponential growth only 40–50 years later by the works of Wulff and especially by Mosbach. More recently, it was also proved that molecular imprinted membranes (i.e., polymer thin films) that show recognition properties at molecular level of the template molecule are used in their formation. Different procedures and potential application in separation processes and catalysis are reported. The influences of different parameters on the discrimination abilities are also discussed. PMID:24958291

  3. Choroidal neovascular membrane

    Directory of Open Access Journals (Sweden)

    Bhatt Nitul

    1998-01-01

    Full Text Available Choroidal neovascular membrane in the macular area is one of the leading causes of severe visual loss. Usually a manifestation in elderly population, it is often associated with age-related macular degeneration. The current mainstay of management is early diagnosis, usually by fundus examination, aided by angiography and photocoagulation in selected cases. Various other modalities of treatment including surgery are being considered as alternate options, but with limited success. The purpose of this review is to briefly outline the current concepts and the management strategy from a clinician′s viewpoint.

  4. Choroidal neovascular membrane.

    Science.gov (United States)

    Bhatt, N S; Diamond, J G; Jalali, S; Das, T

    1998-06-01

    Choroidal neovascular membrane in the macular area is one of the leading causes of severe visual loss. Usually a manifestation in elderly population, it is often associated with age-related macular degeneration. The current mainstay of management is early diagnosis, usually by fundus examination, aided by angiography and photocoagulation in selected cases. Various other modalities of treatment including surgery are being considered as alternate options, but with limited success. The purpose of this review is to briefly outline the current concepts and the management strategy from a clinician's viewpoint.

  5. Tributyltin interacts with mitochondria and induces cytochrome c release.

    Science.gov (United States)

    Nishikimi, A; Kira, Y; Kasahara, E; Sato, E F; Kanno, T; Utsumi, K; Inoue, M

    2001-01-01

    Although triorganotins are potent inducers of apoptosis in various cell types, the critical targets of these compounds and the mechanisms by which they lead to cell death remain to be elucidated. There are two major pathways by which apoptotic cell death occurs: one is triggered by a cytokine mediator and the other is by a mitochondrion-dependent mechanism. To elucidate the mechanism of triorganotin-induced apoptosis, we studied the effect of tributyltin on mitochondrial function. We found that moderately low doses of tributyltin decrease mitochondrial membrane potential and induce cytochrome c release by a mechanism inhibited by cyclosporine A and bongkrekic acid. Tributyltin-induced cytochrome c release is also prevented by dithiols such as dithiothreitol and 2,3-dimercaptopropanol but not by monothiols such as GSH, N-acetyl-L-cysteine, L-cysteine and 2-mercaptoethanol. Further studies with phenylarsine oxide agarose revealed that tributyltin interacts with the adenine nucleotide translocator, a functional constituent of the mitochondrial permeability transition pore, which is selectively inhibited by dithiothreitol. These results suggest that, at low doses, tributyltin interacts selectively with critical thiol residues in the adenine nucleotide translocator and opens the permeability transition pore, thereby decreasing membrane potential and releasing cytochrome c from mitochondria, a series of events consistent with established mechanistic models of apoptosis. PMID:11368793

  6. Acetylcholine release and inhibitory interneuron activity in hippocampal CA1

    Directory of Open Access Journals (Sweden)

    A. Rory McQuiston

    2014-09-01

    Full Text Available Acetylcholine release in the central nervous system (CNS has an important role in attention, recall and memory formation. One region influenced by acetylcholine is the hippocampus, which receives inputs from the medial septum and diagonal band of Broca complex (MS/DBB. Release of acetylcholine from the MS/DBB can directly affect several elements of the hippocampus including glutamatergic and GABAergic neurons, presynaptic terminals, postsynaptic receptors and astrocytes. A significant portion of acetylcholine’s effect likely results from the modulation of GABAergic inhibitory interneurons, which have crucial roles in controlling excitatory inputs, synaptic integration, rhythmic coordination of principal neurons and outputs in the hippocampus. Acetylcholine affects interneuron function in large part by altering their membrane potential via muscarinic and nicotinic receptor activation. This minireview describes recent data from mouse hippocampus that investigated changes in CA1 interneuron membrane potentials following acetylcholine release. The interneuron subtypes affected, the receptor subtypes activated, and the potential outcome on hippocampal CA1 network function is discussed.

  7. Novicidin interactions with phospholipid membranes

    DEFF Research Database (Denmark)

    Balakrishnan, Vijay Shankar

    Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting with lipos......Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting...... with liposomes. The lipid-induced changes in the peptide due to membrane binding, and the peptide-induced changes in the membrane properties were investigated using various spectroscopic and calorimetric methods, and the structural and thermodynamic aspects of peptide-lipid interactions are discussed. This helps...

  8. Mathematical modelling of membrane separation

    DEFF Research Database (Denmark)

    Vinther, Frank

    This thesis concerns mathematical modelling of membrane separation. The thesis consists of introductory theory on membrane separation, equations of motion, and properties of dextran, which will be the solute species throughout the thesis. Furthermore, the thesis consist of three separate mathemat......This thesis concerns mathematical modelling of membrane separation. The thesis consists of introductory theory on membrane separation, equations of motion, and properties of dextran, which will be the solute species throughout the thesis. Furthermore, the thesis consist of three separate...... mathematical models, each with a different approach to membrane separation. The first model is a statistical model investigating the interplay between solute shape and the probability of entering the membrane. More specific the transition of solute particles from being spherical to becoming more elongated...

  9. Radiation effects on cell membranes

    International Nuclear Information System (INIS)

    Koeteles, G.J.

    1982-01-01

    Experimental data are presented concerning the effects of relatively low doses of x radiation and low concentration of tritiated water (HTO) on various receptor functions - concanavalin A, cationized ferritin, poliovirus of plasma membranes of animal and human cells which point to early and temporary disturbances of the composite structures and functions of membranes. References are given to the manifold influence of radiation-induced membrane phenomenon on the development and regeneration of radiation injuries. (author)

  10. Decrumpling membranes by quantum effects

    Science.gov (United States)

    Borelli, M. E. S.; Kleinert, H.

    2001-02-01

    The phase diagram of an incompressible fluid membrane subject to quantum and thermal fluctuations is calculated exactly in a large number of dimensions of configuration space. At zero temperature, a crumpling transition is found at a critical bending rigidity 1/αc. For membranes of fixed lateral size, a crumpling transition occurs at nonzero temperatures in an auxiliary mean field approximation. As the lateral size L of the membrane becomes large, the flat regime shrinks with 1/ln L.

  11. Fabrication and application of coaxial polyvinyl alcohol/chitosan nanofiber membranes

    Directory of Open Access Journals (Sweden)

    Kuo Ting-Yun

    2017-12-01

    Full Text Available It is difficult to fabricate chitosan-wrapped coaxial nanofibers, because highly viscous chitosan solutions might hinder the manufacturing process. To overcome this difficulty, our newly developed method, which included the addition of a small amount of gum arabic, was utilized to prepare much less viscous chitosan solutions. In this way, coaxial polyvinyl alcohol (PVA/chitosan (as core/shell nanofiber membranes were fabricated successfully by coaxial electrospinning. The core/shell structures were confirmed by TEM, and the existence of PVA and chitosan was also verified using FT-IR and TGA. The tensile strength of the nanofiber membranes was increased from 0.6-0.7 MPa to 0.8-0.9 MPa after being crosslinked with glutaraldehyde. The application potential of the PVA/chitosan nanofiber membranes was tested in drug release experiments by loading the core (PVA with theophylline as a model drug. The use of the coaxial PVA/chitosan nanofiber membranes in drug release extended the release time of theophylline from 5 minutes to 24 hours. Further, the release mechanisms could be described by the Korsmeyer-Peppas model. In summary, by combining the advantages of PVA and chitosan (good mechanical strength and good biocompatibility respectively, the coaxial PVA/chitosan nanofiber membranes are potential biomaterials for various biomedical applications.

  12. An AFM-based pit-measuring method for indirect measurements of cell-surface membrane vesicles

    International Nuclear Information System (INIS)

    Zhang, Xiaojun; Chen, Yuan; Chen, Yong

    2014-01-01

    Highlights: • Air drying induced the transformation of cell-surface membrane vesicles into pits. • An AFM-based pit-measuring method was developed to measure cell-surface vesicles. • Our method detected at least two populations of cell-surface membrane vesicles. - Abstract: Circulating membrane vesicles, which are shed from many cell types, have multiple functions and have been correlated with many diseases. Although circulating membrane vesicles have been extensively characterized, the status of cell-surface membrane vesicles prior to their release is less understood due to the lack of effective measurement methods. Recently, as a powerful, micro- or nano-scale imaging tool, atomic force microscopy (AFM) has been applied in measuring circulating membrane vesicles. However, it seems very difficult for AFM to directly image/identify and measure cell-bound membrane vesicles due to the similarity of surface morphology between membrane vesicles and cell surfaces. Therefore, until now no AFM studies on cell-surface membrane vesicles have been reported. In this study, we found that air drying can induce the transformation of most cell-surface membrane vesicles into pits that are more readily detectable by AFM. Based on this, we developed an AFM-based pit-measuring method and, for the first time, used AFM to indirectly measure cell-surface membrane vesicles on cultured endothelial cells. Using this approach, we observed and quantitatively measured at least two populations of cell-surface membrane vesicles, a nanoscale population (<500 nm in diameter peaking at ∼250 nm) and a microscale population (from 500 nm to ∼2 μm peaking at ∼0.8 μm), whereas confocal microscopy only detected the microscale population. The AFM-based pit-measuring method is potentially useful for studying cell-surface membrane vesicles and for investigating the mechanisms of membrane vesicle formation/release

  13. Epiretinal membrane surgery

    DEFF Research Database (Denmark)

    Hamoudi, Hassan; Correll Christensen, Ulrik; La Cour, Morten

    2017-01-01

    Purpose: To assess the impact of combined phacoemulsification-vitrectomy and sequential surgery for idiopathic epiretinal membrane (ERM) on refractive error (RE) and macular morphology. Methods: In this prospective clinical trial, we allocated phakic eyes with ERM to (1) cataract surgery and subs......Purpose: To assess the impact of combined phacoemulsification-vitrectomy and sequential surgery for idiopathic epiretinal membrane (ERM) on refractive error (RE) and macular morphology. Methods: In this prospective clinical trial, we allocated phakic eyes with ERM to (1) cataract surgery...... and achieved spherical equivalent); secondary outcomes were best-corrected visual acuity (BCVA), and incidence of cystoid macular oedema (CME) defined as >10% increment of central subfield macular thickness (CSMT). Results: Sixty-two eyes were enrolled. The mean RE showed a small myopic shift of -0.36D in all...... between the groups. Four cases (17%) in the CAT group had resolved visual complaints and improved BCVA after cataract surgery resulting in no need for PPV within the follow-up period. Conclusion: Surgery for idiopathic ERM in phakic eyes with either phaco-vitrectomy or sequential surgery are equal...

  14. Recognition of acidic phospholipase A2 activity in plasma membranes of resident peritoneal macrophages

    International Nuclear Information System (INIS)

    Shibata, Y.; Abiko, Y.; Ohno, H.; Araki, T.; Takiguchi, H.

    1988-01-01

    Phospholipase (PLase) activities in the plasma membrane of guinea pig peritoneal macrophages were studied, as these enzymes having such activity may be candidates for the release of arachidonic acid (AA) from phosphatidylcholine (PC). An AA release system operating at acidic pH was identified in the macrophage plasma membrane and characterized. This membrane-bound acidic PLase A 2 had an optimum pH at 4.5, and enzyme activation was observed in Ca ++ -free medium; but the maximum activity was found at 0.5 mM Ca ++ concentration. The Km value for PC of acidic PLase A 2 was 4.2 μM, and a Michaelis-Menten relationship was evident. Calcium might act as a cofactor at some intermediate step during the activation of acidic PLase A 2 in light of the uncompetitive manner of Ca ++ action. Furthermore, the release of [ 3 H]-AA from preradiolabelled macrophage plasma membranes occurred with the addition of Ca ++ at pH 4.5. These data suggest that the acid PLase A 2 is a component of the plasma membrane and is not due to lysosomal contamination since membrane-bound acidic PLase A 2 properties are opposite to those found for lysosomal PLase A 2

  15. Drug loaded homogeneous electrospun PCL/gelatin hybrid nanofiber structures for anti-infective tissue regeneration membranes.

    Science.gov (United States)

    Xue, Jiajia; He, Min; Liu, Hao; Niu, Yuzhao; Crawford, Aileen; Coates, Phil D; Chen, Dafu; Shi, Rui; Zhang, Liqun

    2014-11-01

    Infection is the major reason for guided tissue regeneration/guided bone regeneration (GTR/GBR) membrane failure in clinical application. In this work, we developed GTR/GBR membranes with localized drug delivery function to prevent infection by electrospinning of poly(ε-caprolactone) (PCL) and gelatin blended with metronidazole (MNA). Acetic acid (HAc) was introduced to improve the miscibility of PCL and gelatin to fabricate homogeneous hybrid nanofiber membranes. The effects of the addition of HAc and the MNA content (0, 1, 5, 10, 20, 30, and 40 wt.% of polymer) on the properties of the membranes were investigated. The membranes showed good mechanical properties, appropriate biodegradation rate and barrier function. The controlled and sustained release of MNA from the membranes significantly prevented the colonization of anaerobic bacteria. Cells could adhere to and proliferate on the membranes without cytotoxicity until the MNA content reached 30%. Subcutaneous implantation in rabbits for 8 months demonstrated that MNA-loaded membranes evoked a less severe inflammatory response depending on the dose of MNA than bare membranes. The biodegradation time of the membranes was appropriate for tissue regeneration. These results indicated the potential for using MNA-loaded PCL/gelatin electrospun membranes as anti-infective GTR/GBR membranes to optimize clinical application of GTR/GBR strategies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Current-Induced Membrane Discharge

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; van Soestbergen, M.; Mani, A.

    2012-01-01

    . Salt depletion leads to a large electric field resulting in a local pH shift within the membrane with the effect that the membrane discharges and loses its ion selectivity. Since salt co-ions, H+ ions, and OH- ions contribute to OLC, CIMD interferes with electrodialysis (salt counterion removal...... neglects chemical effects and remains to be quantitatively tested. Here, we show that charge regulation and water self-ionization can lead to OLC by "current-induced membrane discharge'' (CIMD), even in the absence of fluid flow, in ion-exchange membranes much thicker than the local Debye screening length...

  17. Track membranes, production, properties, applications

    International Nuclear Information System (INIS)

    Oganesjan, Yu.Ts.

    1994-01-01

    The problems of producing track membranes on heavy ion beams of the Flerov Laboratory are considered. The parameters of the running accelerators and equipment for the irradiation of polymer foils are presented. The process of production of track membranes based on different polymeric materials and various applications of the membranes are described. Special attention is given to the principally new applications and devices developed at the Laboratory. This report presents the results obtained by a big group of scientists and engineers working in the field of elaboration, investigation and application of track membranes (author). 21 refs, 20 figs, 1 tab

  18. Functional microdomains in bacterial membranes.

    Science.gov (United States)

    López, Daniel; Kolter, Roberto

    2010-09-01

    The membranes of eukaryotic cells harbor microdomains known as lipid rafts that contain a variety of signaling and transport proteins. Here we show that bacterial membranes contain microdomains functionally similar to those of eukaryotic cells. These membrane microdomains from diverse bacteria harbor homologs of Flotillin-1, a eukaryotic protein found exclusively in lipid rafts, along with proteins involved in signaling and transport. Inhibition of lipid raft formation through the action of zaragozic acid--a known inhibitor of squalene synthases--impaired biofilm formation and protein secretion but not cell viability. The orchestration of physiological processes in microdomains may be a more widespread feature of membranes than previously appreciated.

  19. Proton exchange membrane fuel cells

    CERN Document Server

    Qi, Zhigang

    2013-01-01

    Preface Proton Exchange Membrane Fuel CellsFuel CellsTypes of Fuel CellsAdvantages of Fuel CellsProton Exchange Membrane Fuel CellsMembraneCatalystCatalyst LayerGas Diffusion MediumMicroporous LayerMembrane Electrode AssemblyPlateSingle CellStackSystemCell Voltage Monitoring Module (CVM)Fuel Supply Module (FSM)Air Supply Module (ASM)Exhaust Management Module (EMM)Heat Management Module (HMM)Water Management Module (WMM)Internal Power Supply Module (IPM)Power Conditioning Module (PCM)Communications Module (COM)Controls Module (CM)SummaryThermodynamics and KineticsTheoretical EfficiencyVoltagePo

  20. Composite membrane with integral rim

    Science.gov (United States)

    Routkevitch, Dmitri; Polyakov, Oleg G

    2015-01-27

    Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

  1. Mechanics of Lipid Bilayer Membranes

    Science.gov (United States)

    Powers, Thomas R.

    All cells have membranes. The plasma membrane encapsulates the cell's interior, acting as a barrier against the outside world. In cells with nuclei (eukaryotic cells), membranes also form internal compartments (organelles) which carry out specialized tasks, such as protein modification and sorting in the case of the Golgi apparatus, and ATP production in the case of mitochondria. The main components of membranes are lipids and proteins. The proteins can be channels, carriers, receptors, catalysts, signaling molecules, or structural elements, and typically contribute a substantial fraction of the total membrane dry weight. The equilibrium properties of pure lipid membranes are relatively well-understood, and will be the main focus of this article. The framework of elasticity theory and statistical mechanics that we will develop will serve as the foundation for understanding biological phenomena such as the nonequilibrium behavior of membranes laden with ion pumps, the role of membrane elasticity in ion channel gating, and the dynamics of vesicle fission and fusion. Understanding the mechanics of lipid membranes is also important for drug encapsulation and delivery.

  2. Amniotic membrane for burn trauma

    International Nuclear Information System (INIS)

    Jamaluddin Zainol; Hasim Mohammad

    1999-01-01

    Amniotic membranes are derived from human placentae at birth. They have two layers mainly the amniotic and the chorionic surfaces which are separated by a thin layer of connective tissues. The two layers are separated during procurement, the placenta and the chorionic side are discarded and the amnion membranes are then further processed. Amnion membranes are normally procured from placentae which are normally free of infections, i.e; the mothers are antenatally screened for sexually transmitted diseases or AlDs related diseases. Intrapartum the mother should not be having chorioamnionitis or jaundice. Sometimes the amniotic membranes are acquired from fresh elective caeserian sections. After processing, the amniotic membranes are packed in two layers of polypropylene and radiated with cobalt 60 at a dose of about 25 kGy. The amniotic membranes are clinically used to cover burn surfaces especially effective for superficial or partial thickness burns. The thin membranes adhered well to the trauma areas and peeled off automatically by the second week. No change of dressing were necessary during these times because of the close adherence, there were less chance of external contamination or infections of these wounds. Due to their flexibility they are very useful to cover difference contours of the human body for example the face, body, elbows or knees. However our experience revealed that amniotic membranes are not useful for third degree bums because the membranes dissolves by the enzymes present in the wounds

  3. Iron release from ferritin and lipid peroxidation by radiolytically generated reducing radicals

    International Nuclear Information System (INIS)

    Reif, D.W.; Schubert, J.; Aust, S.D.

    1988-01-01

    Iron is involved in the formation of oxidants capable of damaging membranes, protein, and DNA. Using 137 Cs gamma radiation, we investigated the release of iron from ferritin and concomitant lipid peroxidation by radiolytically generated reducing radicals, superoxide and the carbon dioxide anion radical. Both radicals released iron from ferritin with similar efficiencies and iron mobilization from ferritin required an iron chelator. Radiolytically generated superoxide anion resulted in peroxidation of phospholipid liposomes as measured by malondialdehyde formation only when ferritin was included as an iron source and the released iron was found to be chelated by the phospholipid liposomes

  4. Ultraviolet radiation stimulates the release of arachidonic acid from mammalian cells in culture

    International Nuclear Information System (INIS)

    De Leo, V.A.; Hanson, D.; Weinstein, I.B.; Harber, L.C.

    1985-01-01

    C3H 10T1/2 cells in culture were prelabelled with [ 3 H]arachidonic acid and exposed to UVB radiation. Almost immediately after irradiation cells released labelled arachidonate metabolites into media in a dose dependent manner. This release was inhibited by removing calcium ions from the system and by the addition of dexamethasone and parabromophenacyl bromide to the system. This suggests that the UVB stimulated release of arachidonic acid from membrane phospholipids is, in part, mediated by a phospholipase A 2 enzyme system. Thin layer chromatographic examination of media extracts revealed a dose dependent UVB stimulation of prostaglandin production by cultured cells. (author)

  5. Dynamic Membrane Formation in Anaerobic Dynamic Membrane Bioreactors: Role of Extracellular Polymeric Substances.

    Directory of Open Access Journals (Sweden)

    Hongguang Yu

    Full Text Available Dynamic membrane (DM formation in dynamic membrane bioreactors plays an important role in achieving efficient solid-liquid separation. In order to study the contribution of extracellular polymeric substances (EPS to DM formation in anaerobic dynamic membrane bioreactor (AnDMBR processes, EPS extraction from and re-addition to bulk sludge were carried out in short-term filtration tests. DM formation behaviors could be well simulated by cake filtration model, and sludge with EPS re-addition showed the highest resistance coefficient, followed by sludge after EPS extraction. The DM layers exhibited a higher resistance and a lower porosity for the sludge sample after EPS extraction and for the sludge with EPS re-addition. Particle size of sludge flocs decreased after EPS extraction, and changed little with EPS re-addition, which was confirmed by interaction energy analysis. Further investigations by confocal laser scanning microscopy (CLSM analysis and batch tests suggested that the removal of in-situ EPS stimulated release of soluble EPS, and re-added EPS were present as soluble EPS rather than bound EPS, which thus improved the formation of DM. The present work revealed the role of EPS in anaerobic DM formation, and could facilitate the operation of AnDMBR processes.

  6. Adaptation of H+-pumping and plasma membrane H+ ATPase activity in proteoid roots of white lupin under phosphate deficiency.

    Science.gov (United States)

    Yan, Feng; Zhu, Yiyong; Müller, Caroline; Zörb, Christian; Schubert, Sven

    2002-05-01

    White lupin (Lupinus albus) is able to adapt to phosphorus deficiency by producing proteoid roots that release a huge amount of organic acids, resulting in mobilization of sparingly soluble soil phosphate in rhizosphere. The mechanisms responsible for the release of organic acids by proteoid root cells, especially the trans-membrane transport processes, have not been elucidated. Because of high cytosolic pH, the release of undissociated organic acids is not probable. In the present study, we focused on H+ export by plasma membrane H+ ATPase in active proteoid roots. In vivo, rhizosphere acidification of active proteoid roots was vanadate sensitive. Plasma membranes were isolated from proteoid roots and lateral roots from P-deficient and -sufficient plants. In vitro, in comparison with two types of lateral roots and proteoid roots of P-sufficient plants, the following increase of the various parameters was induced in active proteoid roots of P-deficient plants: (a) hydrolytic ATPase activity, (b) Vmax and Km, (c) H+ ATPase enzyme concentration of plasma membrane, (d) H+-pumping activity, (e) pH gradient across the membrane of plasmalemma vesicles, and (f) passive H+ permeability of plasma membrane. In addition, lower vanadate sensitivity and more acidic pH optimum were determined for plasma membrane ATPase of active proteoid roots. Our data support the hypothesis that in active proteoid root cells, H+ and organic anions are exported separately, and that modification of plasma membrane H+ ATPase is essential for enhanced rhizosphere acidification by active proteoid roots.

  7. Open circuit voltage durability study and model of catalyst coated membranes at different humidification levels

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Sumit; Fowler, Michael W.; Simon, Leonardo C. [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario (Canada); Abouatallah, Rami; Beydokhti, Natasha [Hydrogenics Corporation, 5985 McLaughlin Road, Mississauga, Ontario (Canada)

    2010-11-01

    Fuel cell material durability is an area of extensive research today. Chemical degradation of the ionomer membrane is one important degradation mechanism leading to overall failure of fuel cells. This study examined the effects of relative humidity on the chemical degradation of the membrane during open circuit voltage testing. Five Gore trademark PRIMEA {sup registered} series 5510 catalyst coated membranes were degraded at 100%, 75%, 50%, and 20% RH. Open circuit potential and cumulative fluoride release were monitored over time. Additionally scanning electron microscopy images were taken at end of the test. The results showed that with decreasing RH fluoride release rate increased as did performance degradation. This was attributed to an increase in gas crossover with a decrease in RH. Further, it is also shown that interruptions in testing may heavily influence cumulative fluoride release measurements where frequent stoppages in testing will cause fluoride release to be underestimated. SEM analysis shows that degradation occurred in the ionomer layer close to the cathode catalyst. A chemical degradation model of the ionomer membrane was used to model the results. The model was able to predict fluoride release trends, including the effects of interruptions, showing that changes in gas crossover with RH could explain the experimental results. (author)

  8. Exclusive photorelease of signalling lipids at the plasma membrane.

    Science.gov (United States)

    Nadler, André; Yushchenko, Dmytro A; Müller, Rainer; Stein, Frank; Feng, Suihan; Mulle, Christophe; Carta, Mario; Schultz, Carsten

    2015-12-21

    Photoactivation of caged biomolecules has become a powerful approach to study cellular signalling events. Here we report a method for anchoring and uncaging biomolecules exclusively at the outer leaflet of the plasma membrane by employing a photocleavable, sulfonated coumarin derivative. The novel caging group allows quantifying the reaction progress and efficiency of uncaging reactions in a live-cell microscopy setup, thereby greatly improving the control of uncaging experiments. We synthesized arachidonic acid derivatives bearing the new negatively charged or a neutral, membrane-permeant coumarin caging group to locally induce signalling either at the plasma membrane or on internal membranes in β-cells and brain slices derived from C57B1/6 mice. Uncaging at the plasma membrane triggers a strong enhancement of calcium oscillations in β-cells and a pronounced potentiation of synaptic transmission while uncaging inside cells blocks calcium oscillations in β-cells and causes a more transient effect on neuronal transmission, respectively. The precise subcellular site of arachidonic acid release is therefore crucial for signalling outcome in two independent systems.

  9. Comparison and analysis of membrane fouling between flocculent sludge membrane bioreactor and granular sludge membrane bioreactor.

    Directory of Open Access Journals (Sweden)

    Wang Jing-Feng

    Full Text Available The goal of this study is to investigate the effect of inoculating granules on reducing membrane fouling. In order to evaluate the differences in performance between flocculent sludge and aerobic granular sludge in membrane reactors (MBRs, two reactors were run in parallel and various parameters related to membrane fouling were measured. The results indicated that specific resistance to the fouling layer was five times greater than that of mixed liquor sludge in the granular MBR. The floc sludge more easily formed a compact layer on the membrane surface, and increased membrane resistance. Specifically, the floc sludge had a higher moisture content, extracellular polymeric substances concentration, and negative surface charge. In contrast, aerobic granules could improve structural integrity and strength, which contributed to the preferable permeate performance. Therefore, inoculating aerobic granules in a MBR presents an effective method of reducing the membrane fouling associated with floc sludge the perspective of from the morphological characteristics of microbial aggregates.

  10. Release plan for Big Pete

    International Nuclear Information System (INIS)

    Edwards, T.A.

    1996-11-01

    This release plan is to provide instructions for the Radiological Control Technician (RCT) to conduct surveys for the unconditional release of ''Big Pete,'' which was used in the removal of ''Spacers'' from the N-Reactor. Prior to performing surveys on the rear end portion of ''Big Pete,'' it shall be cleaned (i.e., free of oil, grease, caked soil, heavy dust). If no contamination is found, the vehicle may be released with the permission of the area RCT Supervisor. If contamination is found by any of the surveys, contact the cognizant Radiological Engineer for decontamination instructions

  11. Commercial SNF Accident Release Fractions

    Energy Technology Data Exchange (ETDEWEB)

    J. Schulz

    2004-11-05

    The purpose of this analysis is to specify and document the total and respirable fractions for radioactive materials that could be potentially released from an accident at the repository involving commercial spent nuclear fuel (SNF) in a dry environment. The total and respirable release fractions are used to support the preclosure licensing basis for the repository. The total release fraction is defined as the fraction of total commercial SNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. Radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses; this subset of the total release fraction is referred to as the respirable release fraction. Accidents may involve waste forms characterized as: (1) bare unconfined intact fuel assemblies, (2) confined intact fuel assemblies, or (3) canistered failed commercial SNF. Confined intact commercial SNF assemblies at the repository are contained in shipping casks, canisters, or waste packages. Four categories of failed commercial SNF are identified: (1) mechanically and cladding-penetration damaged commercial SNF, (2) consolidated/reconstituted assemblies, (3) fuel rods, pieces, and debris, and (4) nonfuel components. It is assumed that failed commercial SNF is placed into waste packages with a mesh screen at each end (CRWMS M&O 1999). In contrast to bare unconfined fuel assemblies, the

  12. Commercial SNF Accident Release Fractions

    International Nuclear Information System (INIS)

    Schulz, J.

    2004-01-01

    The purpose of this analysis is to specify and document the total and respirable fractions for radioactive materials that could be potentially released from an accident at the repository involving commercial spent nuclear fuel (SNF) in a dry environment. The total and respirable release fractions are used to support the preclosure licensing basis for the repository. The total release fraction is defined as the fraction of total commercial SNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. Radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses; this subset of the total release fraction is referred to as the respirable release fraction. Accidents may involve waste forms characterized as: (1) bare unconfined intact fuel assemblies, (2) confined intact fuel assemblies, or (3) canistered failed commercial SNF. Confined intact commercial SNF assemblies at the repository are contained in shipping casks, canisters, or waste packages. Four categories of failed commercial SNF are identified: (1) mechanically and cladding-penetration damaged commercial SNF, (2) consolidated/reconstituted assemblies, (3) fuel rods, pieces, and debris, and (4) nonfuel components. It is assumed that failed commercial SNF is placed into waste packages with a mesh screen at each end (CRWMS M andO 1999). In contrast to bare unconfined fuel assemblies, the

  13. Degradation of Polypropylene Membranes Applied in Membrane Distillation Crystallizer

    Directory of Open Access Journals (Sweden)

    Marek Gryta

    2016-03-01

    Full Text Available The studies on the resistance to degradation of capillary polypropylene membranes assembled in a membrane crystallizer were performed. The supersaturation state of salt was achieved by evaporation of water from the NaCl saturated solutions using membrane distillation process. A high feed temperature (363 K was used in order to enhance the degradation effects and to shorten the test times. Salt crystallization was carried out by the application of batch or fluidized bed crystallizer. A significant membrane scaling was observed regardless of the method of realized crystallization. The SEM-EDS, DSC, and FTIR methods were used for investigations of polypropylene degradation. The salt crystallization onto the membrane surface accelerated polypropylene degradation. Due to a polymer degradation, the presence of carbonyl groups on the membranes’ surface was identified. Besides the changes in the chemical structure a significant mechanical damage of the membranes, mainly caused by the internal scaling, was also found. As a result, the membranes were severely damaged after 150 h of process operation. A high level of salt rejection was maintained despite damage to the external membrane surface.

  14. Release of hepatic Plasmodium yoelii merozoites into the pulmonary microvasculature.

    Directory of Open Access Journals (Sweden)

    Kerstin Baer

    2007-11-01

    Full Text Available Plasmodium undergoes one round of multiplication in the liver prior to invading erythrocytes and initiating the symptomatic blood phase of the malaria infection. Productive hepatocyte infection by sporozoites leads to the generation of thousands of merozoites capable of erythrocyte invasion. Merozoites are released from infected hepatocytes as merosomes, packets of hundreds of parasites surrounded by host cell membrane. Intravital microscopy of green fluorescent protein-expressing P. yoelii parasites showed that the majority of merosomes exit the liver intact, adapt a relatively uniform size of 12-18 microm, and contain 100-200 merozoites. Merosomes survived the subsequent passage through the right heart undamaged and accumulated in the lungs. Merosomes were absent from blood harvested from the left ventricle and from tail vein blood, indicating that the lungs effectively cleared the blood from all large parasite aggregates. Accordingly, merosomes were not detectable in major organs such as brain, kidney, and spleen. The failure of annexin V to label merosomes collected from hepatic effluent indicates that phosphatidylserine is not exposed on the surface of the merosome membrane suggesting the infected hepatocyte did not undergo apoptosis prior to merosome release. Merosomal merozoites continued to express green fluorescent protein and did not incorporate propidium iodide or YO-PRO-1 indicating parasite viability and an intact merosome membrane. Evidence of merosomal merozoite infectivity was provided by hepatic effluent containing merosomes being significantly more infective than blood with an identical low-level parasitemia. Ex vivo analysis showed that merosomes eventually disintegrate inside pulmonary capillaries, thus liberating merozoites into the bloodstream. We conclude that merosome packaging protects hepatic merozoites from phagocytic attack by sinusoidal Kupffer cells, and that release into the lung microvasculature enhances the

  15. Study of polyvinyl alcohol nanofibrous membrane by electrospinning as a magnetic nanoparticle delivery approach

    International Nuclear Information System (INIS)

    Ger, Tzong-Rong; Huang, Hao-Ting; Hu, Keng-Shiang; Huang, Chen-Yu; Lai, Jun-Yang; Chen, Jiann-Yeu; Lai, Mei-Feng

    2014-01-01

    Electrospinning technique was used to fabricate polyvinyl alcohol (PVA)-based magnetic biodegradable nanofibers. PVA solution was mixed with ferrofluid or magnetic nanoparticles (MNPs) powder and formed two individual nanofibrous membranes (PVA/ferrofluid and PVA/MNPs powder) by electrospinning. The surface morphology of the nanofibrous membrane was characterized by scanning electron microscopy and the magnetic properties were measured by vibrating sample magnetometer. Macrophages (RAW 264.7) were co-cultured with the nanofibrous membranes for 12, 24, and 48 h and exhibited good cell viability (>95%). Results showed that the PVA fibers would be degraded and the embedded Fe 3 O 4 nanoparticles would be released and delivered to cells

  16. Pretreatment and Membrane Hydrophilic Modification to Reduce Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Huaqiang Chu

    2013-09-01

    Full Text Available The application of low pressure membranes (microfiltration/ultrafiltration has undergone accelerated development for drinking water production. However, the major obstacle encountered in its popularization is membrane fouling caused by natural organic matter (NOM. This paper firstly summarizes the two factors causing the organic membrane fouling, including molecular weight (MW and hydrophilicity/hydrophobicity of NOM, and then presents a brief introduction of the methods which can prevent membrane fouling such as pretreatment of the feed water (e.g., coagulation, adsorption, and pre-oxidation and membrane hydrophilic modification (e.g., plasma modification, irradiation grafting modification, surface coating modification, blend modification, etc.. Perspectives of further research are also discussed.

  17. Polymorphic solidification of Linezolid confined in electrospun PCL fibers for controlled release in topical applications.

    Science.gov (United States)

    Tammaro, Loredana; Saturnino, Carmela; D'Aniello, Sharon; Vigliotta, Giovanni; Vittoria, Vittoria

    2015-07-25

    Poly(ϵ-caprolactone) (PCL) membranes loaded with Linezolid, chemically N-[[(5S)-3-[3-fluoro-4-(4-morpholinyl)phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (empirical formula C16H20FN3O4) have been prepared by electrospinning technique, at different Linezolid concentrations (0.5, 1, 2.5 and 5%, w/w). Structural characterization, morphological analysis and the study of the mechanical properties have been performed on loaded membranes and compared with neat PCL membranes. Linezolid embedded in the membranes is prevalently amorphous, with a low crystallinity showing a different polymorphic form respect to the usual Form I and Form II. The release kinetics of the drug were studied by spectrophotometric analysis (UV-vis). It allowed to discriminate between Linezolid molecules on the surface and encapsulated into the fibers. The antibacterial activity of the electrospun membranes was effective to inhibit Staphylococcus aureus. The properties of the loaded membranes and their capability for local delivery of the antibiotic make them good candidates as drug release devices for topical use. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Radiation-induced damage of membranes

    International Nuclear Information System (INIS)

    Yonei, Shuji

    1977-01-01

    An outline of membranous structure was stated, and radiation-induced damage of membranes were surveyed. By irradiation, permeability of membranes, especially passive transportation mechanism, was damaged, and glycoprotein in the surface layers of cells and the surface layer structures were changed. The intramembranous damage was induced by decrease of electrophoresis of nuclear mambranes and a quantitative change of cytochrome P450 of microsomal membranes of the liver, and peroxidation of membranous lipid and SH substitute damage of membranous protein were mentioned as the mechanism of membranous damage. Recovery of membranous damage depends on radiation dose and temperature, and membranous damage participates largely in proliferation death. (tsunoda, M.)

  19. Radio-chemical applications of functionalized membranes

    International Nuclear Information System (INIS)

    Pandey, Ashok K.

    2011-01-01

    Functionalized polymer membranes have many potential applications as they are task specific. We have developed many functionalized membranes like polymer inclusion membranes, pore-filled membranes and nano-membranes. Radiotracers and other methods have been used to understand the diffusional-transport properties of the Nafion-117 membrane as well as home-made membranes. These membranes have been used to develop novel analytical and separation methods for toxic metal ions and radionuclides. In this talk, an overview of our work on functionalized membrane is presented. (author)

  20. Operation of staged membrane oxidation reactor systems

    Science.gov (United States)

    Repasky, John Michael

    2012-10-16

    A method of operating a multi-stage ion transport membrane oxidation system. The method comprises providing a multi-stage ion transport membrane oxidation system with at least a first membrane oxidation stage and a second membrane oxidation stage, operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage; and controlling the production capacity and/or the product quality by changing the characteristic temperature of the first membrane oxidation stage and/or changing the characteristic temperature of the second membrane oxidation stage.

  1. Biocompatibility Assessment of PLCL-Sericin Copolymer Membranes Using Wharton’s Jelly Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Kewalin Inthanon

    2016-01-01

    Full Text Available Stem cells based tissue engineering requires biocompatible materials, which allow the cells to adhere, expand, and differentiate in a large scale. An ideal biomaterial for clinical application should be free from mammalian products which cause immune reactivities and pathogen infections. We invented a novel biodegradable poly(L-lactic-co-ε-caprolactone-sericin (PLCL-SC copolymer membrane which was fabricated by electrospinning. Membranes with concentrations of 2.5 or 5% (w/v SC exhibited qualified texture characteristics with a noncytotoxic release profile. The hydrophilic properties of the membranes were 35–40% higher than those of a standard PLCL and commercial polystyrene (PS. The improved characteristics of the membranes were due to an addition of new functional amide groups, C=O, N–H, and C–N, onto their surfaces. Degradation of the membranes was controllable, depending on the content proportion of SC. Results of thermogram indicated the superior stability and crystallinity of the membranes. These membranes enhanced human Wharton’s jelly mesenchymal stem cells (hWJMSC proliferation by increasing cyclin A and also promoted cell adhesion by upregulating focal adhesion kinase (FAK. On the membranes, hWJMSC differentiated into a neuronal lineage with the occurrence of nestin. These data suggest that PLCL-SC electrospun membrane represents some properties which will be useful for tissue engineering and medical applications.

  2. ATP-dependent calcium transport across basal plasma membranes of human placental trophoblast

    International Nuclear Information System (INIS)

    Fisher, G.J.; Kelley, L.K.; Smith, C.H.

    1987-01-01

    As a first step in understanding the cellular basis of maternal-fetal calcium transfer, the authors examined the characteristics of calcium uptake by a highly purified preparation of the syncytiotrophoblast basal (fetal facing) plasma membrane. In the presence of nanomolar concentrations of free calcium, basal membranes demonstrated substantial ATP-dependent calcium uptake. This uptake required magnesium, was not significantly affected by Na + or K + (50 mM), or sodium azide (10 mM). Intravesicular calcium was rapidly and completely released by the calcium ionophore rapidly and completely released by the calcium ionophore A23187. Calcium transport was significantly stimulated by the calcium-dependent regulatory protein calmodulin. Placental membrane fractions enriched in endoplasmic reticulum (ER) and mitochondria also demonstrated ATP-dependent calcium uptake. In contrast to basal membrane, mitochondrial calcium uptake was completely inhibited by azide. The rate of calcium uptake was completely inhibited by azide. The rate of calcium uptake by the ER was only 20% of that of basal membranes. They conclude that the placental basal plasma membrane possesses a high-affinity calcium transport system similar to that found in plasma membranes of a variety of cell types. This transporter is situated to permit it to function in vivo in maternal-fetal calcium transfer

  3. Birth control - slow release methods

    Science.gov (United States)

    Contraception - slow-release hormonal methods; Progestin implants; Progestin injections; Skin patch; Vaginal ring ... might want to consider a different birth control method. SKIN PATCH The skin patch is placed on ...

  4. DEVELOPMENT OF SUSTAINED RELEASE TABLETS ...

    African Journals Online (AJOL)

    2013-12-31

    Dec 31, 2013 ... The SR dosage forms that release drugs pH independently in .... were determined; Post compression parameters such as weight variation test, hardness, ... Based on the ICH guidelines 12, the stability studies were carried out ...

  5. Emergent geometry of membranes

    Energy Technology Data Exchange (ETDEWEB)

    Badyn, Mathias Hudoba de; Karczmarek, Joanna L.; Sabella-Garnier, Philippe; Yeh, Ken Huai-Che [Department of Physics and Astronomy, University of British Columbia,6224 Agricultural Road, Vancouver (Canada)

    2015-11-13

    In work http://dx.doi.org/10.1103/PhysRevD.86.086001, a surface embedded in flat ℝ{sup 3} is associated to any three hermitian matrices. We study this emergent surface when the matrices are large, by constructing coherent states corresponding to points in the emergent geometry. We find the original matrices determine not only shape of the emergent surface, but also a unique Poisson structure. We prove that commutators of matrix operators correspond to Poisson brackets. Through our construction, we can realize arbitrary noncommutative membranes: for example, we examine a round sphere with a non-spherically symmetric Poisson structure. We also give a natural construction for a noncommutative torus embedded in ℝ{sup 3}. Finally, we make remarks about area and find matrix equations for minimal area surfaces.

  6. PCDD/PCDF release inventories

    Energy Technology Data Exchange (ETDEWEB)

    Fiedler, H. [UNEP Chemicals, Chatelaine (Switzerland)

    2004-09-15

    The Stockholm Convention on Persistent Organic Pollutants (POPs) entered into force on 17 May 2004 with 50 Parties. In May 2004, 59 countries had ratified or acceded the Convention. The objective of the Convention is ''to protect human health and the environment from persistent organic pollutants''. For intentionally produced POPs, e.g., pesticides and industrial chemicals such as hexachlorobenzene and polychlorinated biphenyls, this will be achieved by stop of production and use. For unintentionally generated POPs, such as polychlorinated dibenzo-pdioxins (PCDD) and polychlorinated dibenzofurans (PCDF), measures have to be taken to ''reduce the total releases derived from anthropogenic sources''; the final goal is ultimate elimination, where feasible. Under the Convention, Parties have to establish and maintain release inventories to prove the continuous release reduction. Since many countries do not have the technical and financial capacity to measure all releases from all potential PCDD/PCDF sources, UNEP Chemicals has developed the ''Standardized Toolkit for the Identification of Quantification of Dioxin and Furan Releases'' (''Toolkit'' for short), a methodology to estimate annual releases from a number of sources. With this methodology, annual releases can be estimated by multiplying process-specific default emission factors provided in the Toolkit with national activity data. At the seventh session of the Intergovernmental Negotiating Committee, the Toolkit was recommended to be used by countries when reporting national release data to the Conference of the Parties. The Toolkit is especially used by developing countries and countries with economies in transition where no measured data are available. Results from Uruguay, Thailand, Jordan, Philippines, and Brunei Darussalam have been published.

  7. Evaluation of sodium diclofenac release using natural rubber latex as carrier

    International Nuclear Information System (INIS)

    Aielo, Patricia B.; Borges, Felipe A.; Romeira, Karoline M.; Herculano, Rondinelli D.; Miranda, Matheus Carlos Romeiro; Arruda, Larisa B. de; Lisboa Filho, Paulo Noronha; Drago, Bruno de C.

    2014-01-01

    Sodium Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) taken to reduce inflammation and, as an analgesic, reduce pain. Although this drug is widely used in the general population, properties such as the short half-time and some side effects restrict its clinical use. The most common side effects are: gastric irritation, gastritis, peptic ulcer and bleeding. Studies involving biomaterials as carrier for drug release have been proving their efficiency in overcoming those problems and better controlling the release rate and targeting of the drug. Natural rubber latex (NRL) has been proven excellent for its biocompatibility and ability to stimulate angiogenesis, cellular adhesion and the formation of extracellular matrix, promoting the replacement and regeneration of tissue. In this work, a NRL membrane is used to deliver sodium diclofenac. Sodium diclofenac (NaDic) was found to be adsorbed on the NRL membrane, with little or no incorporation into the membrane bulk, according to energy dispersive Scanning Electron Microscopy with X-Ray microanalysis (SEM-EDS) spectroscopy. In addition, FT-IR shows that there is no molecular-level interaction between drug and NRL. Already, the X-Ray Diffraction (XRD) of NaDic-NRL shows a broader one spectrum than the sharper halo (amorphous characteristic XRD spectrum) of pure NRL. More importantly, the release time of diclofenac in a NRL membrane in vitro was increased from the typical 2-3 h for oral tablets to ca. 74 h. The kinetics of the drug release could be fitted with a double exponential function, with two characteristic times of 0.899 and 32.102 h. In this study, we demonstrated that the interesting properties provided by NRL membranes combined with a controlled release of drug is relevant for biomedical applications.(author)

  8. Evaluation of sodium diclofenac release using natural rubber latex as carrier

    Energy Technology Data Exchange (ETDEWEB)

    Aielo, Patricia B.; Borges, Felipe A.; Romeira, Karoline M.; Herculano, Rondinelli D., E-mail: rond@assis.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Assis, SP (Brazil). Fac. de Ciencias e Letras. Dept. de Ciencias Biologicas; Miranda, Matheus Carlos Romeiro [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Inst. de Quimica; Arruda, Larisa B. de; Lisboa Filho, Paulo Noronha; Drago, Bruno de C. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Bauru, SP (Brazil). Fac. de Ciencias. Dept. de Fisica

    2014-08-15

    Sodium Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) taken to reduce inflammation and, as an analgesic, reduce pain. Although this drug is widely used in the general population, properties such as the short half-time and some side effects restrict its clinical use. The most common side effects are: gastric irritation, gastritis, peptic ulcer and bleeding. Studies involving biomaterials as carrier for drug release have been proving their efficiency in overcoming those problems and better controlling the release rate and targeting of the drug. Natural rubber latex (NRL) has been proven excellent for its biocompatibility and ability to stimulate angiogenesis, cellular adhesion and the formation of extracellular matrix, promoting the replacement and regeneration of tissue. In this work, a NRL membrane is used to deliver sodium diclofenac. Sodium diclofenac (NaDic) was found to be adsorbed on the NRL membrane, with little or no incorporation into the membrane bulk, according to energy dispersive Scanning Electron Microscopy with X-Ray microanalysis (SEM-EDS) spectroscopy. In addition, FT-IR shows that there is no molecular-level interaction between drug and NRL. Already, the X-Ray Diffraction (XRD) of NaDic-NRL shows a broader one spectrum than the sharper halo (amorphous characteristic XRD spectrum) of pure NRL. More importantly, the release time of diclofenac in a NRL membrane in vitro was increased from the typical 2-3 h for oral tablets to ca. 74 h. The kinetics of the drug release could be fitted with a double exponential function, with two characteristic times of 0.899 and 32.102 h. In this study, we demonstrated that the interesting properties provided by NRL membranes combined with a controlled release of drug is relevant for biomedical applications.(author)

  9. Modelling of proteins in membranes

    DEFF Research Database (Denmark)

    Sperotto, Maria Maddalena; May, S.; Baumgaertner, A.

    2006-01-01

    This review describes some recent theories and simulations of mesoscopic and microscopic models of lipid membranes with embedded or attached proteins. We summarize results supporting our understanding of phenomena for which the activities of proteins in membranes are expected to be significantly ...

  10. Fabrication of green polymeric membranes

    KAUST Repository

    Kim, Dooli; Nunes, Suzana Pereira

    2017-01-01

    Provided herein are methods of fabricating membranes using polymers with functionalized groups such as sulfone (e.g., PSf and PES), ether (e.g., PES), acrylonitrile (e.g., PAN), fluoride(e.g., pvdf and other fluoropolymers), and imide (e.g., extem) and ionic liquids. Also provided are membranes made by the provided methods.

  11. Gas separation membranes current status

    International Nuclear Information System (INIS)

    Puri, S.P.

    1996-01-01

    Membrane-based gas separation systems are now widely accepted and employed as unit operation in industrial gas, chemical and allied industries. Following their successful commercialization in the late Seventies to recover hydrogen from ammonia purge gas streams, membrane-based systems have gained acceptance in a wide variety of applications

  12. Membranes for Enhanced Emulsification Processes

    NARCIS (Netherlands)

    Güell, Carme; Ferrando, Montse; Schroen, C.G.P.H.

    2016-01-01

    The use of membrane technology for the production of single and double emulsions has been proven feasible for a wide range of systems. The low energy requirements and mild process conditions (shear stress and temperature) of membrane emulsification (ME) compared to conventional processes makes it of

  13. Fabrication of green polymeric membranes

    KAUST Repository

    Kim, Dooli

    2017-06-16

    Provided herein are methods of fabricating membranes using polymers with functionalized groups such as sulfone (e.g., PSf and PES), ether (e.g., PES), acrylonitrile (e.g., PAN), fluoride(e.g., pvdf and other fluoropolymers), and imide (e.g., extem) and ionic liquids. Also provided are membranes made by the provided methods.

  14. Biogenesis of plasma membrane cholesterol

    International Nuclear Information System (INIS)

    Lange, Y.

    1986-01-01

    A striking feature of the molecular organization of eukaryotic cells is the singular enrichment of their plasma membranes in sterols. The authors studies are directed at elucidating the mechanisms underlying this inhomogeneous disposition. Cholesterol oxidase catalyzes the oxidation of plasma membrane cholesterol in intact cells, leaving intracellular cholesterol pools untouched. With this technique, the plasma membrane was shown to contain 95% of the unesterified cholesterol of cultured human fibroblasts. Cholesterol synthesized from [ 3 H] acetate moved to the plasma membrane with a half-time of 1 h at 37 0 C. They used equilibrium gradient centrifugation of homogenates of biosynthetically labeled, cholesterol oxidase treated cells to examine the distribution of newly synthesized sterols among intracellular pools. Surprisingly, lanosterol, a major precursor of cholesterol, and intracellular cholesterol both peaked at much lower buoyant density than did 3-hydroxy-3-methylglutaryl-CoA reductase. This suggests that cholesterol biosynthesis is not taken to completion in the endoplasmic reticulum. The cholesterol in the buoyant fraction eventually moved to the plasma membrane. Digitonin treatment increased the density of the newly synthesized cholesterol fractions, indicating that nascent cholesterol in transit is associated with cholesterol-rich membranes. The authors are testing the hypothesis that the pathway of cholesterol biosynthesis is spatially organized in various intracellular membranes such that the sequence of biosynthetic steps both concentrates the sterol and conveys it to the plasma membrane

  15. Comparison of filtration and treatment performance between polymeric and ceramic membranes in anaerobic membrane bioreactor treatment of domestic wastewater

    KAUST Repository

    Jeong, Yeongmi

    2018-02-28

    The feasibility of an anaerobic ceramic membrane bioreactor (AnCMBR) was investigated by comparison with a conventional anaerobic membrane bioreactor (AnMBR). With regard to treatment performance, the AnCMBR achieved higher organic removal rates than the AnMBR because the ceramic membranes retained a high concentration of biomass in the reactor. Despite a high mixed liquor suspended solid (MLSS) concentration, the AnCMBR exhibited lower membrane fouling. To elucidate effects of sludge properties on membrane fouling in the AnCMBR and AnMBR, soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) were analyzed. The SMP and EPS concentrations in the AnCMBR were higher than in the AnMBR. This may be because some suspended solids bio-degraded and likely released protein-like SMPs in the AnCMBR. Hydrophobicity and surface charges were analyzed; the sludge in the AnCMBR was found to be more hydrophobic and less negative than in the AnMBR because protein was abundant in the AnCMBR. Despite the adverse properties of the sludge in the AnCMBR, it showed more stable filtration performance than the AnMBR. This is because the alumina-based ceramic membrane had a superhydrophilic surface and could thus mitigate membrane fouling by hydrophilic-hydrophobic repulsion. The findings from this study have significant implications for extending the application of AnCMBRs to, for example, treatment of high-strength organic waste such as food waste or livestock manure.

  16. Comparison of filtration and treatment performance between polymeric and ceramic membranes in anaerobic membrane bioreactor treatment of domestic wastewater

    KAUST Repository

    Jeong, Yeongmi; Kim, Youngjin; Jin, Yongxun; Hong, Seungkwan; Park, Chanhyuk

    2018-01-01

    The feasibility of an anaerobic ceramic membrane bioreactor (AnCMBR) was investigated by comparison with a conventional anaerobic membrane bioreactor (AnMBR). With regard to treatment performance, the AnCMBR achieved higher organic removal rates than the AnMBR because the ceramic membranes retained a high concentration of biomass in the reactor. Despite a high mixed liquor suspended solid (MLSS) concentration, the AnCMBR exhibited lower membrane fouling. To elucidate effects of sludge properties on membrane fouling in the AnCMBR and AnMBR, soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) were analyzed. The SMP and EPS concentrations in the AnCMBR were higher than in the AnMBR. This may be because some suspended solids bio-degraded and likely released protein-like SMPs in the AnCMBR. Hydrophobicity and surface charges were analyzed; the sludge in the AnCMBR was found to be more hydrophobic and less negative than in the AnMBR because protein was abundant in the AnCMBR. Despite the adverse properties of the sludge in the AnCMBR, it showed more stable filtration performance than the AnMBR. This is because the alumina-based ceramic membrane had a superhydrophilic surface and could thus mitigate membrane fouling by hydrophilic-hydrophobic repulsion. The findings from this study have significant implications for extending the application of AnCMBRs to, for example, treatment of high-strength organic waste such as food waste or livestock manure.

  17. Magnetically Triggered Release From Giant Unilamellar Vesicles: Visualization By Means Of Confocal Microscopy

    KAUST Repository

    Nappini, Silvia

    2011-04-07

    Magnetically triggered release from magnetic giant unilamellar vesicles (GUVs) loaded with Alexa fluorescent dye was studied by means of confocal laser scanning microscopy (CLSM) under a low-frequency alternating magnetic field (LF-AMF). Core/shell cobalt ferrite nanoparticles coated with rhodamine B isothiocyanate (MP@SiO 2(RITC)) were prepared and adsorbed on the GUV membrane. The MP@SiO 2(RITC) location and distribution on giant lipid vesicles were determined by 3D-CLSM projections, and their effect on the release properties and GUV permeability under a LF-AMF was investigated by CLSM time-resolved experiments. We show that the mechanism of release of the fluorescent dye during the LF-AMF exposure is induced by magnetic nanoparticle energy and mechanical vibration, which promote the perturbation of the GUV membrane without its collapse. © 2011 American Chemical Society.

  18. A Self-Peeling Vat for Improved Release Capabilities During DLP Materials Processing

    DEFF Research Database (Denmark)

    Pedersen, David Bue; Zhang, Yang; Nielsen, Jakob Skov

    2016-01-01

    for an eased release of the manufactured part from the vat by means of a flexible membrane system. A membrane of fluorinated ethylene polymer will through elastic deformation automatically peel off the part as the part is lifted during layer changes. Peeling has been qualified by means of a truncated inverted...... cone as test geometry. As the cross-sectional diameter of the cone increase throughout the build-job, the geometry will release from the glass based build platform at the point where the peeling force exceed the adhesion force between platform and part. At failure point the lateral surface area...... of the top and bottom of the truncated cone is used as a measure of the performance of the vat with respect to release-capability. This has been tested at increasing manufacturing rates. The new self-peeling vat outperformed industrial state-of-the-art vats by 814% percent....

  19. Characterization of Microvesicles Released from Human Red Blood Cells

    Directory of Open Access Journals (Sweden)

    Duc Bach Nguyen

    2016-03-01

    Full Text Available Background/Aims: Extracellular vesicles (EVs are spherical fragments of cell membrane released from various cell types under physiological as well as pathological conditions. Based on their size and origin, EVs are classified as exosome, microvesicles (MVs and apoptotic bodies. Recently, the release of MVs from human red blood cells (RBCs under different conditions has been reported. MVs are released by outward budding and fission of the plasma membrane. However, the outward budding process itself, the release of MVs and the physical properties of these MVs have not been well investigated. The aim of this study is to investigate the formation process, isolation and characterization of MVs released from RBCs under conditions of stimulating Ca2+ uptake and activation of protein kinase C. Methods: Experiments were performed based on single cell fluorescence imaging, fluorescence activated cell sorter/flow cytometer (FACS, scanning electron microscopy (SEM, atomic force microscopy (AFM and dynamic light scattering (DLS. The released MVs were collected by differential centrifugation and characterized in both their size and zeta potential. Results: Treatment of RBCs with 4-bromo-A23187 (positive control, lysophosphatidic acid (LPA, or phorbol-12 myristate-13 acetate (PMA in the presence of 2 mM extracellular Ca2+ led to an alteration of cell volume and cell morphology. In stimulated RBCs, exposure of phosphatidylserine (PS and formation of MVs were observed by using annexin V-FITC. The shedding of MVs was also observed in the case of PMA treatment in the absence of Ca2+, especially under the transmitted bright field illumination. By using SEM, AFM and DLS the morphology and size of stimulated RBCs, MVs were characterized. The sizes of the two populations of MVs were 205.8 ± 51.4 nm and 125.6 ± 31.4 nm, respectively. Adhesion of stimulated RBCs and MVs was observed. The zeta potential of MVs was determined in the range from - 40 mV to - 10 m

  20. Staged membrane oxidation reactor system

    Science.gov (United States)

    Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

    2012-09-11

    Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

  1. Ceramic membrane development in NGK

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Kiyoshi; Sakai, Hitoshi, E-mail: kinsakai@ngk.co.jp [Corporate R and D, NGK Insulators, Ltd., Nagoya 467-8530 (Japan)

    2011-05-15

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R and D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  2. Ceramic membrane development in NGK

    Science.gov (United States)

    Araki, Kiyoshi; Sakai, Hitoshi

    2011-05-01

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R&D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  3. Hydrogen Selective Exfoliated Zeolite Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Tsapatsis, Michael [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Daoutidis, Prodromos [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Elyassi, Bahman [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Lima, Fernando [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Iyer, Aparna [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Agrawal, Kumar [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Sabnis, Sanket [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science

    2015-04-06

    The objective of this project was to develop and evaluate an innovative membrane technology at process conditions that would be representative of Integrated Gasification Combined Cycle (IGCC) advanced power generation with pre-combustion capture of carbon dioxide (CO2). This research focused on hydrogen (H2)-selective zeolite membranes that could be utilized to separate conditioned syngas into H2-rich and CO2-rich components. Both experiments and process design and optimization calculations were performed to evaluate the concept of ultra-thin membranes made from zeolites nanosheets. In this work, efforts in the laboratory were made to tackle two fundamental challenges in application of zeolite membranes in harsh industrial environments, namely, membrane thickness and membrane stability. Conventional zeolite membranes have thicknesses in the micron range, limiting their performance. In this research, we developed a method for fabrication of ultimately thin zeolite membranes based on zeolite nanosheets. A range of layered zeolites (MWW, RWR, NSI structure types) suitable for hydrogen separation was successfully exfoliated to their constituent nanosheets. Further, membranes were made from one of these zeolites, MWW, to demonstrate the potential of this group of materials. Moreover, long-term steam stability of these zeolites (up to 6 months) was investigated in high concentrations of steam (35 mol% and 95 mole%), high pressure (10 barg), and high temperatures (350 °C and 600 °C) relevant to conditions of water-gas-shift and steam methane reforming reactions. It was found that certain nanosheets are stable, and that stability depends on the concentration of structural defects. Additionally, models that represent a water-gas-shift (WGS) membrane reactor equipped with the zeolite membrane were developed for systems studies. These studies had the aim of analyzing the effect of the membrane reactor integration into IGCC plants

  4. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

    DEFF Research Database (Denmark)

    2001-01-01

    A method for preparing polybenzimidazole or polybenzimidazole blend membranes and fabricating gas diffusion electrodes and membrane-electrode assemblies is provided for a high temperature polymer electrolyte membrane fuel cell. Blend polymer electrolyte membranes based on PBI and various...... thermoplastic polymers for high temperature polymer electrolyte fuel cells have also been developed. Miscible blends are used for solution casting of polymer membranes (solid electrolytes). High conductivity and enhanced mechanical strength were obtained for the blend polymer solid electrolytes....... With the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole and other thermoplastics as binder, the carbon-supported noble metal catalyst is tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture, electrodes are assembled with an acid doped solid...

  5. Nanoporous Membrane Technologies for Pathogen Collection, Separation, and Detection

    National Research Council Canada - National Science Library

    Lee, Sang W; Shang, Hao; Lee, Gil U; Griffin, Matthew T; Fulton, Jack

    2003-01-01

    Partial contents: Nanoporous Membranes, Membrane Chemistries, Characterization of Membrane Chemistries,Protein Fouling, Collector,Gas and Liquid Permeabilities, Membrane Permeabilities in the Presence of Water...

  6. Proton migration along the membrane surface in the absence of charged or titratable groups

    International Nuclear Information System (INIS)

    Springer, A.

    2011-01-01

    Proton diffusion along membrane surfaces is thought to be essential for many cellular processes such as energy transduction. For example, proton diffusion along membrane surfaces is considered to be the dominant mechanism of proton exchange between membrane sites of high and low proton concentrations. For the investigation of this mechanism, kinetic experiments on proton diffusion are evaluated to determine the ability of lipid membranes to retain protons on their surfaces. Experiments on different lipid bilayer membranes (DPhPC, DPhPE and GMO) are performed under the influence of two types of mobile buffer molecules (Capso, NH4CL). During these experiments the surface diffusion of photolytically released protons is visualized in terms of fluorescence changes of a lipid bound pH-sensitive dye (DHPE +fluorescein). The protons under investigation are released by flash photolysis of a hydrophobic caged compound (DMCM, caged diethyl phosphate). The experimental data confirm the existence of an energy barrier, which prevents the protons from escaping into the bulk. So far this effect was attributed to the proton binding to titrateable groups (e.g. ethanolamine) or electrostatic forces created by charged moieties (e.g. phosphate groups) on the membrane/water interface. However, upon removal of the titrateable groups and charged moieties from the membrane surface, a significant energy barrier remained as indicated by the experiments with glycerol monooleate (GMO) bilayers. To estimate the size of the barrier a semi-analytical model is presented that describes the two and three dimensional proton diffusion and the related physical and chemical processes. Common models describe surface proton diffusion as a series of subsequent hopping processes between membrane-anchored buffer molecules. Our experiments provide evidence for an alternative model. We released membrane-bound caged protons by UV flashes and monitored their arrival at distant sites s by fluorescence

  7. Drug-model membrane interactions

    International Nuclear Information System (INIS)

    Deniz, Usha K.

    1994-01-01

    In the present day world, drugs play a very important role in medicine and it is necessary to understand their mode of action at the molecular level, in order to optimise their use. Studies of drug-biomembrane interactions are essential for gaining such as understanding. However, it would be prohibitively difficult to carry out such studies, since biomembranes are highly complex systems. Hence, model membranes (made up of these lipids which are important components of biomembranes) of varying degrees of complexity are used to investigate drug-membrane interactions. Bio- as well as model-membranes undergo a chain melting transition when heated, the chains being in a disordered state above the transition point, T CM . This transition is of physiological importance since biomembranes select their components such that T CM is less than the ambient temperature but not very much so, so that membrane flexibility is ensured and porosity, avoided. The influence of drugs on the transition gives valuable clues about various parameters such as the location of the drug in the membrane. Deep insights into drug-membrane interactions are obtained by observing the effect of drugs on membrane structure and the mobilities of the various groups in lipids, near T CM . Investigation of such changes have been carried out with several drugs, using techniques such as DSC, XRD and NMR. The results indicate that the drug-membrane interaction not only depends on the nature of drug and lipids but also on the form of the model membrane - stacked bilayer or vesicles. The light that these results shed on the nature of drug-membrane interactions is discussed. (author). 13 refs., 13 figs., 1 tab

  8. Hydraulic running and release tool with mechanical emergency release

    International Nuclear Information System (INIS)

    Baker, S.F.

    1991-01-01

    This patent describes a setting tool for connection in a well string to position a tubular member in a well bore. It comprises: a mandrel adapted to be connected to the well string; an outer sleeve surrounding the mandrel and releasably secured thereto; a latch nut releasably connected to the outer sleeve; piston means sealingly engaging the mandrel; shear means releasably securing the piston to the latch nut to maintain the latch nut releasably connected to the tubular member; the mandrel having port means for conducting fluid pressure from the well string to release the piston means from and the latch nut; cooperating engageable surfaces on the piston and latch nut to reengage them together after the piston moves a predetermined longitudinal distance relative to the latch nut; and additional cooperating engageable surfaces on the latch nut and the outer sleeve which are engageable when the piston and engaged latch nut are moved a predetermined additional longitudinal distance by fluid pressure to secure the engaged piston and latch nut with the outer sleeve for retrieval along with the mandrel from the well bore

  9. Electrospun superhydrophobic membranes with unique structures for membrane distillation.

    Science.gov (United States)

    Liao, Yuan; Loh, Chun-Heng; Wang, Rong; Fane, Anthony G

    2014-09-24

    With modest temperature demand, low operating pressure, and high solute rejection, membrane distillation (MD) is an attractive option for desalination, waste treatment, and food and pharmaceutical processing. However, large-scale practical applications of MD are still hindered by the absence of effective membranes with high hydrophobicity, high porosity, and adequate mechanical strength, which are important properties for MD permeation fluxes, stable long-term performance, and effective packing in modules without damage. This study describes novel design strategies for highly robust superhydrophobic dual-layer membranes for MD via electrospinning. One of the newly developed membranes comprises a durable and ultrathin 3-dimensional (3D) superhydrophobic skin and porous nanofibrous support whereas another was fabricated by electrospinning 3D superhydrophobic layers on a nonwoven support. These membranes exhibit superhydrophobicity toward distilled water, salty water, oil-in-water emulsion, and beverages, which enables them to be used not only for desalination but also for other processes. The superhydrophobic dual-layer membrane #3S-N with nanofibrous support has a competitive permeation flux of 24.6 ± 1.2 kg m(-2) h(-1) in MD (feed and permeate temperate were set as 333 and 293 K, respectively) due to the higher porosity of the nanofibrous scaffold. Meanwhile, the membranes with the nonwoven support exhibit greater mechanical strength due to this support combined with better long-term performance because of the thicker 3D superhydrophobic layers. The morphology, pore size, porosity, mechanical properties, and liquid enter pressure of water of these superhydrophobic composite membranes with two different structures are reported and compared with commercial polyvinylidene fluoride membranes.

  10. Innovative hybrid biological reactors using membranes

    International Nuclear Information System (INIS)

    Diez, R.; Esteban-Garcia, A. L.; Florio, L. de; Rodriguez-Hernandez, L.; Tejero, I.

    2011-01-01

    In this paper we present two lines of research on hybrid reactors including the use of membranes, although with different functions: RBPM, biofilm reactors and membranes filtration RBSOM, supported biofilm reactors and oxygen membranes. (Author) 14 refs.

  11. Polymer nanocomposite membranes with hierarchically structured catalysts for high throughput dehalogenation

    Science.gov (United States)

    Crock, Christopher A.

    Halogenated organics are categorized as primary pollutants by the Environmental Protection Agency. Trichloroethylene (TCE), which had broad industrial use in the past, shows persistence in the environment because of its chemical stability. The large scale use and poor control of TCE resulted in its prolonged release into the environment before the carcinogenic risk associated with TCE was fully understood. TCE pollution stemmed from industrial effluents and improper disposal of solvent waste. Membrane reactors are promising technology for treating TCE polluted groundwater because of the high throughput, relatively low cost of membrane fabrication and facile retrofitting of existing membrane based water treatment facilities with catalytic membrane reactors. Compared to catalytic fluidized or fixed bed reactors, catalytic membrane reactors feature minimal diffusional limitation. Additionally, embedding catalyst within the membrane avoids the need for catalyst recovery and can prevent aggregation of catalytic nanoparticles. In this work, Pd/xGnP, Pd-Au/xGnP, and commercial Pd/Al2O3 nanoparticles were employed in batch and flow-through membrane reactors to catalyze the dehalogenation of TCE in the presence of dissolved H2. Bimetallic Pd-Au/xGnP catalysts were shown to be more active than monometallic Pd/xGnP or commercial Pd/Al 2O3 catalysts. In addition to synthesizing nanocomposite membranes for high-throughput TCE dehalogenation, the membrane based dehalogenation process was designed to minimize the detrimental impact of common catalyst poisons (S2-, HS-, and H2S -) by concurrent oxidation of sulfide species to gypsum in the presence of Ca2+ and removal of gypsum through membrane filtration. The engineered membrane dehalogenation process demonstrated that bimetallic Pd-Au/xGnP catalysts resisted deactivation by residual sulfide species after oxidation, and showed complete removal of gypsum during membrane filtration.

  12. Investigation of activity release during light water reactor core meltdown

    International Nuclear Information System (INIS)

    Albrecht, H.; Matschoss, V.; Wild, H.

    1978-01-01

    A test facility was developed for the determination of activity release and of aerosol characteristics under realistic light water reactor core melting conditions. It is composed of a high-frequency induction furnace, a ThO 2 crucible system, and a collection apparatus consisting of membrane and particulate filters. Thirty-gram samples of a representative core material mixture (corium) were melted under air, argon, or steam at 0.8 to 2.2 bar. In air at 2700 0 C, for example, the relative release was 0.4 to 0.7% for iron, chromium, and cobalt and 4 to 11% for tin, antimony, and manganese. Higher release values of 20 to 40% at lower temperatures (2150 0 C, air) were found for selenium, cadmium, tellurium, and cesium. The size distribution of the aerosol particles was trimodal with maxima at diameters of 0.17, 0.30, and 0.73 μm. The result of a qualitative x-ray microanalysis was that the main elements of the melt were contained in each aerosol particle. Further investigations will include larger melt masses and the additional influence of concrete on the release and aerosol behavior

  13. Electrically induced release of acetylcholine from denervated Schwann cells.

    Science.gov (United States)

    Dennis, M J; Miledi, R

    1974-03-01

    1. Focal electrical stimulation of Schwann cells at the end-plates of denervated frog muscles elicited slow depolarizations of up to 30 mV in the muscle fibres. This response is referred to as a Schwann-cell end-plate potential (Schwann-e.p.p.).2. Repeated stimulation sometimes evoked further Schwann-e.p.p.s, but they were never sustained for more than 30 pulses. Successive e.p.p.s varied in amplitude and time course independently of the stimulus.3. The Schwann-e.p.p.s were reversibly blocked by curare, suggesting that they result from a release of acetylcholine (ACh) by the Schwann cells.4. ACh release by electrical stimulation did not seem to occur in quantal form and was not dependent on the presence of calcium ions in the external medium; nor was it blocked by tetrodotoxin.5. Stimulation which caused release of ACh also resulted in extensive morphological disruption of the Schwann cells, as seen with both light and electron microscopy.6. It is concluded that electrical stimulation of denervated Schwann cells causes break-down of the cell membrane and releases ACh, presumably in molecular form.

  14. Microbubbles-Assisted Ultrasound Triggers the Release of Extracellular Vesicles

    Directory of Open Access Journals (Sweden)

    Yuana Yuana

    2017-07-01

    Full Text Available Microbubbles-assisted ultrasound (USMB has shown promise in improving local drug delivery. The formation of transient membrane pores and endocytosis are reported to be enhanced by USMB, and they contribute to cellular drug uptake. Exocytosis also seems to be linked to endocytosis upon USMB treatment. Based on this rationale, we investigated whether USMB triggers exocytosis resulting in the release of extracellular vesicles (EVs. USMB was performed on a monolayer of head-and-neck cancer cells (FaDu with clinically approved microbubbles and commonly used ultrasound parameters. At 2, 4, and 24 h, cells and EV-containing conditioned media from USMB and control conditions (untreated cells, cells treated with microbubbles and ultrasound only were harvested. EVs were measured using flow cytometric immuno-magnetic bead capture assay, immunogold electron microscopy, and western blotting. After USMB, levels of CD9 exposing-EVs significantly increased at 2 and 4 h, whereas levels of CD63 exposing-EVs increased at 2 h. At 24 h, EV levels were comparable to control levels. EVs released after USMB displayed a heterogeneous size distribution profile (30–1200 nm. Typical EV markers CD9, CD63, and alix were enriched in EVs released from USMB-treated FaDu cells. In conclusion, USMB treatment triggers exocytosis leading to the release of EVs from FaDu cells.

  15. Releases of radioactivity from uranium mills and effluent treatment costs

    International Nuclear Information System (INIS)

    Witherspoon, J.P.; Sears, M.B.; Blanco, R.E.

    1977-01-01

    Airborne releases of radioactive materials from uranium milling to the environment consist of ore dust, yellowcake dust, tailings dust, and radon gas while the mill is active. After a mill has ceased operations, tailings may be stabilized to minimize or prevent airborne releases of radioactive particulates. However, radon gas will continue to be released in amounts inversely proportional to the degree of stabilization treatment (and expense). Liquid waste disposal is by evaporation and natural seepage to the ground beneath the tailings impoundment area. The release of radioactive materials (and potential radiation exposures) determines the majority of costs associated with minimizing the environmental impact of uranium milling. Radwaste treatments to reduce estimated radiation doses to individuals to 3 to 5% of those received with current milling practices are equivalent to $0.66 per pounds of U 3 O 8 and 0.032 mill per kWhr of electricity. This cost would cover a high efficiency reverse jet bag filter and high energy venturi scrubbers for dusts, neutralization of liquids, and an asphalt-lined tailings basin with a clay core dam to reduce seepage. In addition, this increased cost would cover stabilization of tailings, after mill closure, with a 1-in. asphalt membrane topped by 2 ft of earth and 0.5 ft of crushed rock to provide protection against future leaching and wind erosion. The cost of reducing the radiological hazards associated with uranium milling to this degree would contribute about 0.4% to the current total cost of nuclear power

  16. Hydrogen superpermeable membrane operation under plasma conditions

    International Nuclear Information System (INIS)

    Bacal, M.; Bruneteau, A.M.; Livshits, A.I.; Alimov, V.N.; Notkin, M.E.

    2003-01-01

    The effect of ion bombardment on hydrogen plasma-driven permeation through a superpermeable niobium membrane was investigated. It was found that the increase of membrane temperature and the doping of membrane material with oxygen results in the decrease of ion bombardment effect and in permeability increase. It was demonstrated that membrane decarbonization leads to the formation of a membrane state resistant to sputtering. Possible applications of the membrane resistant to ion bombardment as plasma facing components are considered

  17. Development of paradigm for the study of amino acid neurotransmitter release in human autopsy brain samples

    International Nuclear Information System (INIS)

    Kuo, K.-W.; Dodd, P.R.

    2001-01-01

    Full text: This study attempted to establish a release protocol to characterize both the vesicular and cytoplasmic components of amino acid transmitter release in human synaptosomes. Experiments with rat synaptosomes showed that, with depolarizing concentrations of K + ions, vesicular release could be successfully differentiated from cytoplasmic release for preloaded L-[ 3 H ]glutamate and [ 14 C ]GABA. However, human tissue studies did not give clear-cut results. Experiments were carried out to optimize the release paradigm as well as to improve the vesicular uptake of labeled transmitters. A 'pulse- chase' protocol, with an unlabelled D-aspartate chase, was performed in human tissue samples in order to enhance the L-[ 3 H ] glutamate release signal derived from exocytosis by removing the cytoplasmic pool of L-[ 3 H ] glutamate first. However, the results showed that total release was not enhanced effectively in comparison with the non-pulse-chase protocol. In brief, the pulse-chase protocol did not build up the vesicular pool of L-[ 3 H ]glutamate, though the cytoplasmic L- [ 3 H ] glutamate pool was effectively depressed by D-aspartate. Further studies applied 4- aminopyridine (4-AP) to trigger release, to circumvent the problem of the reversal of plasma membrane transporters caused by raised K + ion concentrations. The results showed that the application of 4-AP elicited the release of amino acid transmitters from rat synaptosomes, but failed to produce successful release signals in the human tissue experiments. Our findings suggest that the vesicular compartment may be impaired by freezing and affected by post-mortem delay (PMD). Rat studies showed that the freezing step had a major effect on Ca 2+-dependent release, as less L- [3 H ]glutamate and [ 14 C ]GABA were released from the frozen rat tissue preparations. Moreover, there was an indication of a decline in L-[ 3 H ]glutamate release with increasing PMD. Copyright (2001) Australian Neuroscience Society

  18. alpha-difluoromethylornithine modifies gonadotropin-releasing hormone release and follicle-stimulating hormone secretion in the immature female rat.

    Science.gov (United States)

    Thyssen, S M; Becú-Villalobos, D; Lacau-Mengido, I M; Libertun, C

    1997-06-01

    Polyamines play an essential role in tissue growth and differentiation, in body weight increment, in brain organization, and in the molecular mechanisms of hormonal action, intracellular signaling, and cell-to-cell communication. In a previous study, inhibition of their synthesis by alpha-difluoromethylornithine (DFMO), a specific and irreversible inhibitor of ornithine decarboxylase, during development in female rats, was followed by prolonged high follicle-stimulating hormone (FSH) serum level and a delayed puberty onset. Those changes were relatively independent of body mass and did not impair posterior fertility. The present work studies the mechanisms and site of action of polyamine participation in FSH secretion during development. DFMO was injected in female rats between Days 1 and 9 on alternate days. At 10 days of age, hypothalami from control and DFMO rats were perifused in vitro, and basal and potassium-induced gonadotropin-releasing hormone (GnRH) release were measured. The response to membrane depolarization was altered in DFMO hypothalami. Increased GnRH release in response to a low K+ concentration was evidenced. Adenohypophyses of the same treated prepubertal rats were perifused in vitro and the response to GnRH pulses was checked. In DFMO-treated rats, higher FSH release was observed, with no changes in LH or PRL secretion. Finally, pituitary GnRH receptor number in adenohypophyseal membranes from treated and control groups was quantified. A significant reduction in specific binding was evident in hypophyses from DFMO-treated rats when compared with binding in the control group. In summary, DFMO treatment in a critical developmental period in the female rat impacts the immature GnRH neuronal network and immature gonadotropes. A delay in maturation is evidenced by a higher sensitivity to secretagogs in both pituitary glands and hypothalamic explants. These events could explain the prolonged high FSH serum levels and delayed puberty onset seen in

  19. Predicting hydrocarbon release from soil

    International Nuclear Information System (INIS)

    Poppendieck, D.; Loehr, R.C.

    2002-01-01

    'Full text:' The remediation of hazardous chemicals from soils can be a lengthy and costly process. As a result, recent regulatory initiatives have focused on risk-based corrective action (RBCA) approaches. Such approaches attempt to identify the amount of chemical that can be left at a site with contaminated soil and still be protective of human health and the environment. For hydrocarbons in soils to pose risk to human heath and the environment, the hydrocarbons must be released from the soil and accessible to microorganisms, earthworms, or other higher level organisms. The sorption of hydrocarbons to soil can reduce the availability of the hydrocarbon to receptors. Typically in soils and sediments, there is an initial fast release of a hydrocarbon from the soil to the aqueous phase followed by a slower release of the remaining hydrocarbon to the aqueous phase. The rate and extent of slow release can influence aqueous hydrocarbon concentrations and the fate and transport of hydrocarbons in the subsurface. Once the fast fraction of the chemical has been removed from the soil, the remaining fraction of a chemical may desorb at a rate that natural mechanisms can attenuate the released hydrocarbon. Hence, active remediation may be needed only until the fast fraction has been removed. However, the fast fraction is a soil and chemical specific parameter. This presentation will present a tier I type protocol that has been developed to quickly estimate the fraction of hydrocarbons that are readily released from the soil matrix to the aqueous phase. Previous research in our laboratory and elsewhere has used long-term desorption (four months) studies to determine the readily released fraction. This research shows that a single short-term (less than two weeks) batch extraction procedure provides a good estimate of the fast released fraction derived from long-term experiments. This procedure can be used as a tool to rapidly evaluate the release and bioavailability of

  20. Membrane manufacture for peptide separations

    KAUST Repository

    Kim, Dooli; Salazar Moya, Octavio Ruben; Nunes, Suzana Pereira

    2016-01-01

    Nanostructured polymeric membranes are key tools in biomedical applications such as hemodialysis, protein separations, in the food industry, and drinking water supply from seawater. Despite of the success in different separation processes, membrane manufacture itself is at risk, since the most used solvents are about to be banned in many countries due to environmental and health issues. We propose for the first time the preparation of polyethersulfone membranes based on dissolution in the ionic liquid 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM]DEP). We obtained a series of membranes tailored for separation of solutes with molecular weight of 30, 5, 1.3, and 1.25 kg mol-1 with respective water permeances of 140, 65, 30 and 20 Lm-2h-1bar-1. We demonstrate their superior efficiency in the separation of complex mixtures of peptides with molecular weights in the range of 800 to 3500 gmol-1. Furthermore, the thermodynamics and kinetics of phase separation leading to the pore formation in the membranes were investigated. The rheology of the solutions and the morphology of the prepared membranes were examed and compared to those of polyethersulfone in organic solvents currently used for membrane manufacture.

  1. FAS grafted superhydrophobic ceramic membrane

    Energy Technology Data Exchange (ETDEWEB)

    Lu Jun [School of Material Science and Engineering, Jingdezhen Ceramic Institute, 333001 Jingdezhen (China); Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, CAS, 1295 DingXi Road, Shanghai 200050 (China); Yu Yun, E-mail: yunyush@mail.sic.ac.cn [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, CAS, 1295 DingXi Road, Shanghai 200050 (China); Zhou Jianer [School of Material Science and Engineering, Jingdezhen Ceramic Institute, 333001 Jingdezhen (China); Song Lixin; Hu Xingfang [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, CAS, 1295 DingXi Road, Shanghai 200050 (China); Larbot, Andre [Institut Europeen des Membranes, UMR 5635-CNRS, ENSCM, UMII, 1919 Route de Mende 34293, Montpellier Cedex 5 (France)

    2009-08-30

    The hydrophobic properties of {gamma}-Al{sub 2}O{sub 3} membrane have been obtained by grafting fluoroalkylsilane (FAS) on the surface of the membrane. The following grafting parameters were studied: the eroding time of the original membrane, the grafting time, the concentration of FAS solution and the multiplicity of grafting. Hydrophobicity of the membranes was characterized by contact angle (CA) measurement. The thermogravimetric analysis (TGA) was used to investigate the weight loss process (25-800 deg. C) of the fluoroalkylsilane grafted on Al{sub 2}O{sub 3} powders under different grafting conditions. The morphologies of the membranes modified under different parameters were examined by field emission scanning electron microscopy (FE-SEM) and the surface roughness (Ra) was measured using white light interferometers. A needle-like structure was observed on the membrane surface after modification, which causes the change of Ra. On the results above, we speculated a model to describe the reaction between FAS and {gamma}-Al{sub 2}O{sub 3} membrane surface as well as the formed surface morphology.

  2. FAS grafted superhydrophobic ceramic membrane

    Science.gov (United States)

    Lu, Jun; Yu, Yun; Zhou, Jianer; Song, Lixin; Hu, Xingfang; Larbot, Andre

    2009-08-01

    The hydrophobic properties of γ-Al 2O 3 membrane have been obtained by grafting fluoroalkylsilane (FAS) on the surface of the membrane. The following grafting parameters were studied: the eroding time of the original membrane, the grafting time, the concentration of FAS solution and the multiplicity of grafting. Hydrophobicity of the membranes was characterized by contact angle (CA) measurement. The thermogravimetric analysis (TGA) was used to investigate the weight loss process (25-800 °C) of the fluoroalkylsilane grafted on Al 2O 3 powders under different grafting conditions. The morphologies of the membranes modified under different parameters were examined by field emission scanning electron microscopy (FE-SEM) and the surface roughness (Ra) was measured using white light interferometers. A needle-like structure was observed on the membrane surface after modification, which causes the change of Ra. On the results above, we speculated a model to describe the reaction between FAS and γ-Al 2O 3 membrane surface as well as the formed surface morphology.

  3. Membrane manufacture for peptide separations

    KAUST Repository

    Kim, Dooli

    2016-06-07

    Nanostructured polymeric membranes are key tools in biomedical applications such as hemodialysis, protein separations, in the food industry, and drinking water supply from seawater. Despite of the success in different separation processes, membrane manufacture itself is at risk, since the most used solvents are about to be banned in many countries due to environmental and health issues. We propose for the first time the preparation of polyethersulfone membranes based on dissolution in the ionic liquid 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM]DEP). We obtained a series of membranes tailored for separation of solutes with molecular weight of 30, 5, 1.3, and 1.25 kg mol-1 with respective water permeances of 140, 65, 30 and 20 Lm-2h-1bar-1. We demonstrate their superior efficiency in the separation of complex mixtures of peptides with molecular weights in the range of 800 to 3500 gmol-1. Furthermore, the thermodynamics and kinetics of phase separation leading to the pore formation in the membranes were investigated. The rheology of the solutions and the morphology of the prepared membranes were examed and compared to those of polyethersulfone in organic solvents currently used for membrane manufacture.

  4. Ultrastructure of Reissner's membrane in the rabbit

    DEFF Research Database (Denmark)

    Qvortrup, K.; Rostgaard, Jørgen; Bretlau, P.

    1994-01-01

    Anatomy, Reissner's membrane, electron microscopy, tubulocisternal endoplasmic reticulum, subsurface cisterns, rabbit......Anatomy, Reissner's membrane, electron microscopy, tubulocisternal endoplasmic reticulum, subsurface cisterns, rabbit...

  5. Nanofluidics : Silicon for the perfect membrane

    NARCIS (Netherlands)

    van den Berg, Albert; Wessling, Matthias

    2007-01-01

    Newly developed ultrathin silicon membranes can filter and separate molecules much more effectively than conventional polymer membranes. Many applications, of economic and medical significance, stand to benefit.

  6. GEWEX SRB Shortwave Release 4

    Science.gov (United States)

    Cox, S. J.; Stackhouse, P. W., Jr.; Mikovitz, J. C.; Zhang, T.

    2017-12-01

    The NASA/GEWEX Surface Radiation Budget (SRB) project produces shortwave and longwave surface and top of atmosphere radiative fluxes for the 1983-near present time period. Spatial resolution is 1 degree. The new Release 4 uses the newly processed ISCCP HXS product as its primary input for cloud and radiance data. The ninefold increase in pixel number compared to the previous ISCCP DX allows finer gradations in cloud fraction in each grid box. It will also allow higher spatial resolutions (0.5 degree) in future releases. In addition to the input data improvements, several important algorithm improvements have been made since Release 3. These include recalculated atmospheric transmissivities and reflectivities yielding a less transmissive atmosphere. The calculations also include variable aerosol composition, allowing for the use of a detailed aerosol history from the Max Planck Institut Aerosol Climatology (MAC). Ocean albedo and snow/ice albedo are also improved from Release 3. Total solar irradiance is now variable, averaging 1361 Wm-2. Water vapor is taken from ISCCP's nnHIRS product. Results from GSW Release 4 are presented and analyzed. Early comparison to surface measurements show improved agreement.

  7. Aluminum corrosion product release kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matt, E-mail: Matthew.Edwards@cnl.ca; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna

    2015-07-15

    Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

  8. Radioiodinated nondegradable gonadotropin-releasing hormone analogs: new probes for the investigation of pituitary gonadotropin-releasing hormone receptors.

    Science.gov (United States)

    Clayton, R N; Shakespear, R A; Duncan, J A; Marshall, J C; Munson, P J; Rodbard, D

    1979-12-01

    Studies of pituitary plasma membrane gonadotropin-releasing hormone (GnRH) receptors using [125I]-iodo-GnRH suffer major disadvantages. Only a small (less than 25%) proportion of specific tracer binding is to high affinity sites, with more than 70% bound to low affinity sites (Ka = 1 x 10(6) M-1). [125I]Iodo-GnRH is also inactivated during incubation with pituitary plasma membrane preparations. Two superactive analongs of GnRH, substituted in positions 6 and 10, were used as the labeled ligand to overcome these problems. Both analogs bound to the same high affinity sites as GnRH on bovine pituitary plasma membranes, though the affinity of the analogs was higher than that of the natural decapeptide (Ka = 2.0 x 10(9), 6.0 x 10(9), and 3.0 x 10(8) M-1 for [D-Ser(TBu)6]des-Gly10-GnRH ethylamide, [D-Ala6]des-Gly10-GnRH ethylamide, and GnRH, respectively. The labeled analogs bound to a single class of high affinity sites with less than 15% of the specific binding being to low affinity sites (Ka approximately equal to 1 x 10(6) M-1). The labeled analogs were not inactivated during incubation with the pituitary membrane preparations. Using the analogs as tracer, a single class of high affinity sites (K1 = 4.0 x 10(9) M-1) was also demonstrated on crude 10,800 x g rat pituitary membrane preparations. Use of these analogs as both the labeled and unlabeled ligand offers substantial advantages over GnRH for investigation of GnRH receptors, allowing accurate determination of changes in their numbers and affinities under various physiological conditions.

  9. Isolation of plasma membrane-associated membranes from rat liver.

    Science.gov (United States)

    Suski, Jan M; Lebiedzinska, Magdalena; Wojtala, Aleksandra; Duszynski, Jerzy; Giorgi, Carlotta; Pinton, Paolo; Wieckowski, Mariusz R

    2014-02-01

    Dynamic interplay between intracellular organelles requires a particular functional apposition of membrane structures. The organelles involved come into close contact, but do not fuse, thereby giving rise to notable microdomains; these microdomains allow rapid communication between the organelles. Plasma membrane-associated membranes (PAMs), which are microdomains of the plasma membrane (PM) interacting with the endoplasmic reticulum (ER) and mitochondria, are dynamic structures that mediate transport of proteins, lipids, ions and metabolites. These structures have gained much interest lately owing to their roles in many crucial cellular processes. Here we provide an optimized protocol for the isolation of PAM, PM and ER fractions from rat liver that is based on a series of differential centrifugations, followed by the fractionation of crude PM on a discontinuous sucrose gradient. The procedure requires ∼8-10 h, and it can be easily modified and adapted to other tissues and cell types.

  10. Diffusion of Integral Membrane Proteins in Protein-Rich Membranes

    DEFF Research Database (Denmark)

    Javanainen, Matti; Martinez-Seara, Hector; Metzler, Ralf

    2017-01-01

    of being protein-poor, native cell membranes are extremely crowded with proteins. On the basis of extensive molecular simulations, we here demonstrate that protein crowding of the membrane at physiological levels leads to deviations from the SD relation and to the emergence of a stronger Stokes......-like dependence D ∝ 1/R. We propose that this 1/R law mainly arises due to geometrical factors: smaller proteins are able to avoid confinement effects much better than their larger counterparts. The results highlight that the lateral dynamics in the crowded setting found in native membranes is radically different......The lateral diffusion of embedded proteins along lipid membranes in protein-poor conditions has been successfully described in terms of the Saffman-Delbrück (SD) model, which predicts that the protein diffusion coefficient D is weakly dependent on its radius R as D ∝ ln(1/R). However, instead...

  11. Amniotic Membrane Transplantation

    Directory of Open Access Journals (Sweden)

    Alireza Baradaran-Rafii

    2008-12-01

    Full Text Available

    The past decade has witnessed the revival of amniotic membrane transplantation (AMT in ophthalmology. The importance of amniotic membrane lies in its ability to reduce inflammation and scarring, enhance epithelialization and wound healing, and in its antimicrobial properties. Amniotic membrane has recently been used as a substrate for culturing limbal stem cells for transplantation. It has also been used extensively in corneal conditions such as neurotrophic ulcers, persistent epithelial defects, shield ulcers, microbial keratitis, band keratopathy, bullous keratopathy, and following photorefractive keratectomy and chemical injuries. Other indications for AMT include ocular surface reconstruction surgery for conjunctival pathologies such as squamous neoplasia, pterygium, and symblepharon. In this review we describe the basic structure and properties of amniotic membrane, its preparation process and its applications in ophthalmology.

  1. Controlled Release from Recombinant Polymers

    Science.gov (United States)

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

  2. ATP Release from Human Airway Epithelial Cells Exposed to Staphylococcus aureus Alpha-Toxin

    Directory of Open Access Journals (Sweden)

    Romina Baaske

    2016-12-01

    Full Text Available Airway epithelial cells reduce cytosolic ATP content in response to treatment with S. aureus alpha-toxin (hemolysin A, Hla. This study was undertaken to investigate whether this is due to attenuated ATP generation or to release of ATP from the cytosol and extracellular ATP degradation by ecto-enzymes. Exposure of cells to rHla did result in mitochondrial calcium uptake and a moderate decline in mitochondrial membrane potential, indicating that ATP regeneration may have been attenuated. In addition, ATP may have left the cells through transmembrane pores formed by the toxin or through endogenous release channels (e.g., pannexins activated by cellular stress imposed on the cells by toxin exposure. Exposure of cells to an alpha-toxin mutant (H35L, which attaches to the host cell membrane but does not form transmembrane pores, did not induce ATP release from the cells. The Hla-mediated ATP-release was completely blocked by IB201, a cyclodextrin-inhibitor of the alpha-toxin pore, but was not at all affected by inhibitors of pannexin channels. These results indicate that, while exposure of cells to rHla may somewhat reduce ATP production and cellular ATP content, a portion of the remaining ATP is released to the extracellular space and degraded by ecto-enzymes. The release of ATP from the cells may occur directly through the transmembrane pores formed by alpha-toxin.

  3. Vacuum membrane distillation of liquid desiccants Utilizing Hollow Fiber Membranes

    KAUST Repository

    Lefers, Ryan; Srivatsa Bettahalli, N.M.; Fedoroff, Nina V.; Nunes, Suzana Pereira; Leiknes, TorOve

    2018-01-01

    This paper documents the testing of a vacuum membrane distillation system intended for use with liquid desiccants. Liquid desiccants offer the possibility for low-energy, ambient temperature dehumidification. Effective desalination and purification of diluted desiccants outputs two important products: a concentrated desiccant for reuse in dehumidification and fresh water. In this study, vacuum membrane distillation was used in the laboratory to purify diluted liquid desiccants. Calcium chloride and magnesium chloride were the desiccants selected for testing. Desiccant solutions were pumped through the lumens of poly(vinylidene fluoride) (PVDF) hollow fiber membranes at varying feed inlet temperatures, solution velocity rates and vacuum set points during membrane distillation. An average flux of 8 kg m-2 h-1 was obtained using 30 wt% magnesium chloride solution at a temperature of 50 °C while applying vacuum to achieve 25 mbar absolute pressure on the air side of the membrane. The results are promising for the development of a full-scale vacuum membrane distillation process for desiccant solution regeneration and fresh water recovery. In addition, the recovered condensate was of sufficient quality for use in agricultural irrigation or drinking water.

  4. Vacuum membrane distillation of liquid desiccants Utilizing Hollow Fiber Membranes

    KAUST Repository

    Lefers, Ryan

    2018-01-31

    This paper documents the testing of a vacuum membrane distillation system intended for use with liquid desiccants. Liquid desiccants offer the possibility for low-energy, ambient temperature dehumidification. Effective desalination and purification of diluted desiccants outputs two important products: a concentrated desiccant for reuse in dehumidification and fresh water. In this study, vacuum membrane distillation was used in the laboratory to purify diluted liquid desiccants. Calcium chloride and magnesium chloride were the desiccants selected for testing. Desiccant solutions were pumped through the lumens of poly(vinylidene fluoride) (PVDF) hollow fiber membranes at varying feed inlet temperatures, solution velocity rates and vacuum set points during membrane distillation. An average flux of 8 kg m-2 h-1 was obtained using 30 wt% magnesium chloride solution at a temperature of 50 °C while applying vacuum to achieve 25 mbar absolute pressure on the air side of the membrane. The results are promising for the development of a full-scale vacuum membrane distillation process for desiccant solution regeneration and fresh water recovery. In addition, the recovered condensate was of sufficient quality for use in agricultural irrigation or drinking water.

  5. The Role of Ion Exchange Membranes in Membrane Capacitive Deionisation.

    Science.gov (United States)

    Hassanvand, Armineh; Wei, Kajia; Talebi, Sahar; Chen, George Q; Kentish, Sandra E

    2017-09-14

    Ion-exchange membranes (IEMs) are unique in combining the electrochemical properties of ion exchange resins and the permeability of a membrane. They are being used widely to treat industrial effluents, and in seawater and brackish water desalination. Membrane Capacitive Deionisation (MCDI) is an emerging, energy efficient technology for brackish water desalination in which these ion-exchange membranes act as selective gates allowing the transport of counter-ions toward carbon electrodes. This article provides a summary of recent developments in the preparation, characterization, and performance of ion exchange membranes in the MCDI field. In some parts of this review, the most relevant literature in the area of electrodialysis (ED) is also discussed to better elucidate the role of the ion exchange membranes. We conclude that more work is required to better define the desalination performance of the proposed novel materials and cell designs for MCDI in treating a wide range of feed waters. The extent of fouling, the development of cleaning strategies, and further techno-economic studies, will add value to this emerging technique.

  6. Nanostructured Diclofenac Sodium Releasing Material

    Science.gov (United States)

    Nikkola, L.; Vapalahti, K.; Harlin, A.; Seppälä, J.; Ashammakhi, N.

    2008-02-01

    Various techniques have been developed to produce second generation biomaterials for tissue repair. These include extrusion, molding, salt leaching, spinning etc, but success in regenerating tissues has been limited. It is important to develop porous material, yet with a fibrous structure for it to be biomimetic. To mimic biological tissues, the extra-cellular matrix usually contains fibers in nano scale. To produce nanostructures, self-assembly or electrospinning can be used. Adding a drug release function to such a material may advance applications further for use in controlled tissue repair. This turns the resulting device into a multifunctional porous, fibrous structure to support cells and drug releasing properties in order to control tissue reactions. A bioabsorbable poly(ɛ-caprolactone-co-D,L lactide) 95/5 (PCL) was made into diluted solution using a solvent, to which was added 2w-% of diclofenac sodium (DS). Nano-fibers were made by electrospinning onto substrate. Microstructure of the resulting nanomat was studied using SEM and drug release profiles with UV/VIS spectroscopy. Thickness of the electrospun nanomat was about 2 mm. SEM analysis showed that polymeric nano-fibers containing drug particles form a highly interconnected porous nano structure. Average diameter of the nano-fibers was 130 nm. There was a high burst peak in drug release, which decreased to low levels after one day. The used polymer has slow a degradation rate and though the nanomat was highly porous with a large surface area, drug release rate is slow. It is feasible to develop a nano-fibrous porous structure of bioabsorbable polymer, which is loaded with test drug. Drug release is targeted at improving the properties of biomaterial for use in controlled tissue repair and regeneration.

  7. Loss of outer membrane integrity in Gram-negative bacteria by silver ...

    Indian Academy of Sciences (India)

    plausible mechanism of bacterial cell disintegration ... New generation antimicrobial and smart drugs are the needs of the present era in fighting microbial ... charides (LPSs) in nature where the lipid portion acts ... sive release of LPS molecules and membrane proteins [10]. ... efficacy of antimicrobial action on Gram bacteria.

  8. Evaluation of nanofiltration membranes for treatment of liquid radioactive waste

    International Nuclear Information System (INIS)

    Oliveira, Elizabeth Eugenio de Mello

    2013-01-01

    The physicochemical behavior of two nanofiltration membranes for treatment of a low-level radioactive liquid waste (carbonated water) was investigated through static, dynamic and concentration tests. This waste was produced during conversion of uranium hexafluoride (UF 6 ) to uranium dioxide (UO 2 ) in the cycle of nuclear fuel. This waste contains about 7.0 mg L -1 of uranium and cannot be discarded to the environment without an adequate treatment. In static tests membrane samples were immersed in the waste for 24 to 5000 h. Their transport properties (hydraulic permeability, permeate flux, sulfate and chloride ions rejection) were evaluated before and after immersion in the waste using a permeation flux front system under 0.5 MPa. The selective layer (polyamide) was characterized by zeta potential, contact angle, scanning electron microscopy for field emission, atomic force microscopy, infrared spectroscopy, x-ray fluorescence and thermogravimetric analysis before and after static tests. In dynamic tests the waste was permeated under 0.5 MPa, and the membranes showed rejection to uranium above 85% were obtained. The short-term static tests (24-72 h) showed that the selective layer and surface charge of the membranes were not chemical changed, according infrared spectra data. After 5000 h a coating layer was released from the membranes, poly(vinyl alcohol), PVA. After this loss the rejection for uranium decreased. Permeation and concentration of the waste were carried out in permeation flux tangential system under 1.5 MPa. The rejection of uranium was around 90% for permeation tests. In concentration tests the permeated was collected continuously until about 80% reduction of the feed volume. The rejection of uranium was of the 97%. The nanofiltration membranes tested were efficient to concentrate the uranium from the waste. (author)

  9. Extended latanoprost release from commercial contact lenses: in vitro studies using corneal models.

    Directory of Open Access Journals (Sweden)

    Saman Mohammadi

    Full Text Available In this study, we compared, for the first time, the release of a 432 kDa prostaglandin F2a analogue drug, Latanoprost, from commercially available contact lenses using in vitro models with corneal epithelial cells. Conventional polyHEMA-based and silicone hydrogel soft contact lenses were soaked in drug solution (131 μg = ml solution in phosphate buffered saline. The drug release from the contact lens material and its diffusion through three in vitro models was studied. The three in vitro models consisted of a polyethylene terephthalate (PET membrane without corneal epithelial cells, a PET membrane with a monolayer of human corneal epithelial cells (HCEC, and a PET membrane with stratified HCEC. In the cell-based in vitro corneal epithelium models, a zero order release was obtained with the silicone hydrogel materials (linear for the duration of the experiment whereby, after 48 hours, between 4 to 6 μg of latanoprost (an amount well within the range of the prescribed daily dose for glaucoma patients was released. In the absence of cells, a significantly lower amount of drug, between 0.3 to 0.5 μg, was released, (p <0:001. The difference observed in release from the hydrogel lens materials in the presence and absence of cells emphasizes the importance of using an in vitro corneal model that is more representative of the physiological conditions in the eye to more adequately characterize ophthalmic drug delivery materials. Our results demonstrate how in vitro models with corneal epithelial cells may allow better prediction of in vivo release. It also highlights the potential of drug-soaked silicone hydrogel contact lens materials for drug delivery purposes.

  10. Limited Releases of Krsko NPP

    International Nuclear Information System (INIS)

    Breznik, B.; Kovac, A.

    2001-01-01

    Full text: Krsko Nuclear Power Plant is about 700 MW Pressurised Water Reactor plant located in Slovenia close to the border with Croatia. The authorised limit for the radioactive releases is basically set to 50 μSv effective dose per year to the members of the public. There is also additional limitation of total activities released in a year and concentration. The poster presents the effluents of the year 2000 and evaluated dose referring to the limits and to the natural and other sources of radiation around the plant. (author)

  11. Ion Transport across Biological Membranes by Carborane-Capped Gold Nanoparticles.

    Science.gov (United States)

    Grzelczak, Marcin P; Danks, Stephen P; Klipp, Robert C; Belic, Domagoj; Zaulet, Adnana; Kunstmann-Olsen, Casper; Bradley, Dan F; Tsukuda, Tatsuya; Viñas, Clara; Teixidor, Francesc; Abramson, Jonathan J; Brust, Mathias

    2017-12-26

    Carborane-capped gold nanoparticles (Au/carborane NPs, 2-3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with a potentiostat in an electrochemical cell or by competition with another partitioning ion, for example, potassium in the presence of its specific transporter valinomycin. Carborane-capped gold nanoparticles have a ligand shell full of voids, which stem from the packing of near spherical ligands on a near spherical metal core. These voids are normally filled with sodium or potassium ions, and the charge is overcompensated by excess electrons in the metal core. The anionic particles are therefore able to take up and release a certain payload of cations and to adjust their net charge accordingly. It is demonstrated by potential-dependent fluorescence spectroscopy that polarized phospholipid membranes of vesicles can be depolarized by ion transport mediated by the particles. It is also shown that the particles act as alkali-ion-specific transporters across free-standing membranes under potentiostatic control. Magnesium ions are not transported.

  12. One-way membrane trafficking of SOS in receptor-triggered Ras activation.

    Science.gov (United States)

    Christensen, Sune M; Tu, Hsiung-Lin; Jun, Jesse E; Alvarez, Steven; Triplet, Meredith G; Iwig, Jeffrey S; Yadav, Kamlesh K; Bar-Sagi, Dafna; Roose, Jeroen P; Groves, Jay T

    2016-09-01

    SOS is a key activator of the small GTPase Ras. In cells, SOS-Ras signaling is thought to be initiated predominantly by membrane recruitment of SOS via the adaptor Grb2 and balanced by rapidly reversible Grb2-SOS binding kinetics. However, SOS has multiple protein and lipid interactions that provide linkage to the membrane. In reconstituted-membrane experiments, these Grb2-independent interactions were sufficient to retain human SOS on the membrane for many minutes, during which a single SOS molecule could processively activate thousands of Ras molecules. These observations raised questions concerning how receptors maintain control of SOS in cells and how membrane-recruited SOS is ultimately released. We addressed these questions in quantitative assays of reconstituted SOS-deficient chicken B-cell signaling systems combined with single-molecule measurements in supported membranes. These studies revealed an essentially one-way trafficking process in which membrane-recruited SOS remains trapped on the membrane and continuously activates Ras until being actively removed via endocytosis.

  13. Photoresponsive molecularly imprinted hydrogel casting membrane for the determination of trace tetracycline in milk.

    Science.gov (United States)

    Wang, Qiang; Lv, Zhen; Tang, Qian; Gong, Cheng-Bin; Lam, Michael Hon Wah; Ma, Xue-Bing; Chow, Cheuk-Fai

    2016-03-01

    This study aimed to develop a photoresponsive molecularly imprinted hydrogel (MIH) casting membrane for the determination of trace tetracycline (TC) in milk. This MIH casting membrane combined the specificity of MIHs, the photoresponsive properties of azobenzene, and the portable properties of a membrane. Photoresponsive TC-imprinted MIHs were initially fabricated and then cast on sodium dodecyl sulfonate polyacrylamide gel. After TC removal, a photoresponsive MIH casting membrane was obtained. The photoresponsive properties of the MIH casting membrane were robust, and no obvious photodegradation was observed after 20 cycles. The MIH casting membrane displayed specific affinity to TC upon alternate irradiation at 365 and 440 nm; it could quantitatively uptake and release TC. The TC concentration (0.0-2.0 × 10(-4) mol l(-1)) in aqueous solution displayed a linear relationship with the photoisomerization rate constant of azobenzene within the MIH casting membrane. As such, a quick detection method for trace TC in aqueous foodstuff samples was established. The recovery of this method for TC in milk was investigated with a simple pretreatment of milk, and a high recovery of 100.54-106.35% was obtained. Therefore, the fabricated membrane can be used as a portable molecular sensor that can be easily recycled. Copyright © 2015 John Wiley & Sons, Ltd.

  14. Acoustic investigation of the aperture dynamics of an elastic membrane closing an overpressurized cylindrical cavity

    Science.gov (United States)

    Sánchez, Claudia; Vidal, Valérie; Melo, Francisco

    2015-08-01

    We report an experimental study of the acoustic signal produced by the rupture of an elastic membrane that initially closes a cylindrical overpressurized cavity. This configuration has been recently used as an experimental model system for the investigation of the acoustic emission from the bursting of elongated gas bubbles rising in a conduit. Here, we investigate the effect of the membrane rupture dynamics on the acoustic signal produced by the pressure release by changing the initial tension of the membrane. The initial overpressure in the cavity is fixed at a value such that the system remains in the linear acoustic regime. For large initial membrane deformation, the rupture time τ rup is small compared to the wave propagation time in the cavity and the pressure wave inside the conduit can be fully captured by the linear theory. For low membrane tension, a hole is pierced in the membrane but its rupture does not occur. For intermediate deformation, finally, the rupture progresses in two steps: first the membrane opens slowly; then, after reaching a critical size, the rupture accelerates. A transversal wave is excited along the membrane surface. The characteristic signature of each opening dynamics on the acoustic emission is described.

  15. A photo-tunable membrane based on inter-particle crosslinking for decreasing diffusion rates

    KAUST Repository

    Li, Song

    2015-01-01

    Functional polymeric membranes are widely used to adjust and control the diffusion of molecules. Herein, photosensitive poly(hydroxycinnamic acid) (PHCA) microspheres, which were fabricated by an emulsification solvent-evaporation method, were embedded into an ethyl cellulose matrix to fabricate composite membranes with a photo-tunable property. The photoreaction of PHCA is based on the [2 + 2] cycloaddition of cinnamic moieties upon irradiation with 365 nm light. Intra-particle crosslinking in PHCA microspheres was confirmed in the solution phase, while inter-particle crosslinking between adjacent PHCA microspheres dominated the solid membrane phase. The inter-particle crosslinking turned down the permeability of the composite membranes by 74%. To prove the applicability of the designed system, the composite membrane was coated on a model drug reservoir tablet. Upon irradiating the tablet with UV light, the original permeability decreased by 57%, and consequently the diffusion rate of the cargo (Rhodamine B) from the tablet slowed down. Most importantly, the tablet showed sustained release for over 10 days. This controllability can be further tuned by adjusting the membrane thickness. Composite membranes showed excellent processing reproducibility together with consistent mechanical properties. These results demonstrate that the incorporation of photosensitive PHCA microspheres in polymeric membranes provides a promising photo-tunable material for different applications including coating and separation. This journal is © The Royal Society of Chemistry 2015.

  16. Positive zeta potential of a negatively charged semi-permeable plasma membrane

    Science.gov (United States)

    Sinha, Shayandev; Jing, Haoyuan; Das, Siddhartha

    2017-08-01

    The negative charge of the plasma membrane (PM) severely affects the nature of moieties that may enter or leave the cells and controls a large number of ion-interaction-mediated intracellular and extracellular events. In this letter, we report our discovery of a most fascinating scenario, where one interface (e.g., membrane-cytosol interface) of the negatively charged PM shows a positive surface (or ζ) potential, while the other interface (e.g., membrane-electrolyte interface) still shows a negative ζ potential. Therefore, we encounter a completely unexpected situation where an interface (e.g., membrane-cytosol interface) that has a negative surface charge density demonstrates a positive ζ potential. We establish that the attainment of such a property by the membrane can be ascribed to an interplay of the nature of the membrane semi-permeability and the electrostatics of the electric double layer established on either side of the charged membrane. We anticipate that such a membrane property can lead to such capabilities of the cell (in terms of accepting or releasing certain kinds of moieties as well regulating cellular signaling) that was hitherto inconceivable.

  17. Layered plasma polymer composite membranes

    Science.gov (United States)

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  18. Lysosomal degradation of membrane lipids.

    Science.gov (United States)

    Kolter, Thomas; Sandhoff, Konrad

    2010-05-03

    The constitutive degradation of membrane components takes place in the acidic compartments of a cell, the endosomes and lysosomes. Sites of lipid degradation are intralysosomal membranes that are formed in endosomes, where the lipid composition is adjusted for degradation. Cholesterol is sorted out of the inner membranes, their content in bis(monoacylglycero)phosphate increases, and, most likely, sphingomyelin is degraded to ceramide. Together with endosomal and lysosomal lipid-binding proteins, the Niemann-Pick disease, type C2-protein, the GM2-activator, and the saposins sap-A, -B, -C, and -D, a suitable membrane lipid composition is required for degradation of complex lipids by hydrolytic enzymes. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  19. Membrane Trafficking and Vesicle Fusion

    Indian Academy of Sciences (India)

    IAS Admin

    protein and the data can be cor- related with cellular .... these mutant cells under the electron microscope and found a large number of ... trans-Golgi network and early ..... Arrows represent the flow of membrane traffic: black arrows – antero-.

  20. Uniquely different PVA-xanthan gum irradiated membranes as transdermal diltiazem delivery device.

    Science.gov (United States)

    Bhunia, Tridib; Giri, Arindam; Nasim, Tanbir; Chattopadhyay, Dipankar; Bandyopadhyay, Abhijit

    2013-06-05

    This paper reports interesting differences between physical and mechanical properties of various membranes prepared from high and low molecular weight poly (vinyl alcohol) (PVA) and xanthan gum (XG) blends irradiated under low dose electron beam. The membranes were designed for sustained delivery of diltiazem hydrochloride through skin. Electron beam irradiation produced crosslinks and turned PVA into crystalline phase from its amorphous organization in the unirradiated state. PVA crystals were fibrillar at low XG content (1 wt.%) when the molecular weight was high while similar orientation at higher XG content (5 wt.%) when the molecular weight was low. Low molecular weight PVA-XG membranes showed equivalent physical properties under dry condition but wet-mechanical properties were superior for high molecular weight PVA-XG hybrids. Both of them showed slow and sustained diltiazem release but the later induced slightly slower release despite low drug encapsulation efficiency due to its better wet mechanical strength. Copyright © 2013 Elsevier Ltd. All rights reserved.