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Sample records for ionically bound cell

  1. Evidence against the involvement of ionically bound cell wall proteins in pea epicotyl growth

    NASA Technical Reports Server (NTRS)

    Melan, M. A.; Cosgrove, D. J.

    1988-01-01

    Ionically bound cell wall proteins were extracted from 7 day old etiolated pea (Pisum sativum L. cv Alaska) epicotyls with 3 molar LiCl. Polyclonal antiserum was raised in rabbits against the cell wall proteins. Growth assays showed that treatment of growing region segments (5-7 millimeters) of peas with either dialyzed serum, serum globulin fraction, affinity purified immunoglobulin, or papain-cleaved antibody fragments had no effect on growth. Immunofluorescence microscopy confirmed antibody binding to cell walls and penetration of the antibodies into the tissues. Western blot analysis, immunoassay results, and affinity chromatography utilizing Sepharose-bound antibodies confirmed recognition of the protein preparation by the antibodies. Experiments employing in vitro extension as a screening measure indicated no effect upon extension by antibodies, by 50 millimolar LiCl perfusion of the apoplast or by 3 molar LiCl extraction. Addition of cell wall protein to protease pretreated segments did not restore extension nor did addition of cell wall protein to untreated segments increase extension. It is concluded that, although evidence suggests that protein is responsible for the process of extension, the class(es) of proteins which are extracted from pea cell walls with 3 molar LiCl are probably not involved in this process.

  2. Evidence against the involvement of ionically bound cell wall proteins in pea epicotyl growth

    NASA Technical Reports Server (NTRS)

    Melan, M. A.; Cosgrove, D. J.

    1988-01-01

    Ionically bound cell wall proteins were extracted from 7 day old etiolated pea (Pisum sativum L. cv Alaska) epicotyls with 3 molar LiCl. Polyclonal antiserum was raised in rabbits against the cell wall proteins. Growth assays showed that treatment of growing region segments (5-7 millimeters) of peas with either dialyzed serum, serum globulin fraction, affinity purified immunoglobulin, or papain-cleaved antibody fragments had no effect on growth. Immunofluorescence microscopy confirmed antibody binding to cell walls and penetration of the antibodies into the tissues. Western blot analysis, immunoassay results, and affinity chromatography utilizing Sepharose-bound antibodies confirmed recognition of the protein preparation by the antibodies. Experiments employing in vitro extension as a screening measure indicated no effect upon extension by antibodies, by 50 millimolar LiCl perfusion of the apoplast or by 3 molar LiCl extraction. Addition of cell wall protein to protease pretreated segments did not restore extension nor did addition of cell wall protein to untreated segments increase extension. It is concluded that, although evidence suggests that protein is responsible for the process of extension, the class(es) of proteins which are extracted from pea cell walls with 3 molar LiCl are probably not involved in this process.

  3. Evidence against the involvement of ionically bound cell wall proteins in pea epicotyl growth.

    PubMed

    Melan, M A; Cosgrove, D J

    1988-01-01

    Ionically bound cell wall proteins were extracted from 7 day old etiolated pea (Pisum sativum L. cv Alaska) epicotyls with 3 molar LiCl. Polyclonal antiserum was raised in rabbits against the cell wall proteins. Growth assays showed that treatment of growing region segments (5-7 millimeters) of peas with either dialyzed serum, serum globulin fraction, affinity purified immunoglobulin, or papain-cleaved antibody fragments had no effect on growth. Immunofluorescence microscopy confirmed antibody binding to cell walls and penetration of the antibodies into the tissues. Western blot analysis, immunoassay results, and affinity chromatography utilizing Sepharose-bound antibodies confirmed recognition of the protein preparation by the antibodies. Experiments employing in vitro extension as a screening measure indicated no effect upon extension by antibodies, by 50 millimolar LiCl perfusion of the apoplast or by 3 molar LiCl extraction. Addition of cell wall protein to protease pretreated segments did not restore extension nor did addition of cell wall protein to untreated segments increase extension. It is concluded that, although evidence suggests that protein is responsible for the process of extension, the class(es) of proteins which are extracted from pea cell walls with 3 molar LiCl are probably not involved in this process.

  4. Immobilization of flax protoplasts in agarose and alginate beads. Correlation between ionically bound cell-wall proteins and morphogenetic response.

    PubMed Central

    Roger, D; David, A; David, H

    1996-01-01

    Linum usitatissimum protoplast-derived colonies that are cultured in auxin-supplemented medium and immobilized in Ca(2+)-alginate matrix form round colonies that develop into polarized, embryo-like structures. On the other hand, protoplast-derived colonies that are immobilized in agarose do not show an organized morphogenetic response, and unique, ionically bound cell-wall protein patterns match this response. Although only slight differences in neosynthesized or total constitutive polypeptides are observed, dramatic changes in ionically bound cell-wall proteins are seen. In protoplasts grown on Ca(2+)-alginate-solidified, auxin-containing medium, several basic polypeptides were strongly induced and were found tightly bound to the cell wall. In contrast, these basic proteins were found only weakly bound to the walls of protoplasts grown on agarose-solidified, auxin-containing medium or on Ca(2+)-alginate-solidified, auxin-free medium, in which they were released into the medium. Our results suggest that plant cells can perceive and respond to the adjacent extracellular matrix, since we show that the growth of flax cells on Ca(2+)-alginate in the presence of auxin-containing medium may promote the binding of specific proteins to the walls. This establishes a direct correlation of an embryo-like morphogenesis with ionically bound cell-wall basic proteins in flax protoplasts grown on Ca(2+)-alginate-solidified, auxin-containing medium. PMID:8938417

  5. Identifying the ionically bound cell wall and intracellular glycoside hydrolases in late growth stage Arabidopsis stems: implications for the genetic engineering of bioenergy crops.

    PubMed

    Wei, Hui; Brunecky, Roman; Donohoe, Bryon S; Ding, Shi-You; Ciesielski, Peter N; Yang, Shihui; Tucker, Melvin P; Himmel, Michael E

    2015-01-01

    Identifying the cell wall-ionically bound glycoside hydrolases (GHs) in Arabidopsis stems is important for understanding the regulation of cell wall integrity. For cell wall proteomics studies, the preparation of clean cell wall fractions is a challenge since cell walls constitute an open compartment, which is more likely to contain a mixture of intracellular and extracellular proteins due to cell leakage at the late growth stage. Here, we utilize a CaCl2-extraction procedure to isolate non-structural proteins from Arabidopsis whole stems, followed by the in-solution and in-gel digestion methods coupled with Nano-LC-MS/MS, bioinformatics and literature analyses. This has led to the identification of 75 proteins identified using the in-solution method and 236 proteins identified by the in-gel method, among which about 10% of proteins predicted to be secreted. Together, eight cell wall proteins, namely AT1G75040, AT5G26000, AT3G57260, AT4G21650, AT3G52960, AT3G49120, AT5G49360, and AT3G14067, were identified by the in-solution method; among them, three were the GHs (AT5G26000, myrosinase 1, GH1; AT3G57260, β-1,3-glucanase 2, GH17; AT5G49360, bifunctional XYL 1/α-L-arabinofuranosidase, GH3). Moreover, four more GHs: AT4G30270 (xyloglucan endotransferase, GH16), AT1G68560 (bifunctional α-l-arabinofuranosidase/XYL, GH31), AT1G12240 (invertase, GH32) and AT2G28470 (β-galactosidase 8, GH35), were identified by the in-gel solution method only. Notably, more than half of above identified GHs are xylan- or hemicellulose-modifying enzymes, and will likely have an impact on cellulose accessibility, which is a critical factor for downstream enzymatic hydrolysis of plant tissues for biofuels production. The implications of these cell wall proteins identified at the late growth stage for the genetic engineering of bioenergy crops are discussed.

  6. Identifying the ionically bound cell wall and intracellular glycoside hydrolases in late growth stage Arabidopsis stems: Implications for the genetic engineering of bioenergy crops

    DOE PAGES

    Wei, Hui; Brunecky, Roman; Donohoe, Bryon S.; ...

    2015-05-13

    Identifying the cell wall-ionically bound glycoside hydrolases (GHs) in Arabidopsis stems is important for understanding the regulation of cell wall integrity. For cell wall proteomics studies, the preparation of clean cell wall fractions is a challenge since cell walls constitute an open compartment, which is more likely to contain a mixture of intracellular and extracellular proteins due to cell leakage at the late growth stage. Here, for this study, we utilize a CaCl2-extraction procedure to isolate non-structural proteins from Arabidopsis whole stems, followed by the in-solution and in-gel digestion methods coupled with Nano-LC-MS/MS, bioinformatics and literature analyses. This has ledmore » to the identification of 75 proteins identified using the in-solution method and 236 proteins identified by the in-gel method, among which about 10% of proteins predicted to be secreted. Together, eight cell wall proteins, namely AT1G75040, AT5G26000, AT3G57260, AT4G21650, AT3G52960, AT3G49120, AT5G49360, and AT3G14067, were identified by the in-solution method; among them, three were the GHs (AT5G26000, myrosinase 1, GH1; AT3G57260, β-1,3-glucanase 2, GH17; AT5G49360, bifunctional XYL 1/α-L-arabinofuranosidase, GH3). Moreover, four more GHs: AT4G30270 (xyloglucan endotransferase, GH16), AT1G68560 (bifunctional α-l-arabinofuranosidase/XYL, GH31), AT1G12240 (invertase, GH32) and AT2G28470 (β-galactosidase 8, GH35), were identified by the in-gel solution method only. Notably, more than half of above identified GHs are xylan- or hemicellulose-modifying enzymes, and will likely have an impact on cellulose accessibility, which is a critical factor for downstream enzymatic hydrolysis of plant tissues for biofuels production. Finally, the implications of these cell wall proteins identified at the late growth stage for the genetic engineering of bioenergy crops are discussed.« less

  7. Identifying the ionically bound cell wall and intracellular glycoside hydrolases in late growth stage Arabidopsis stems: Implications for the genetic engineering of bioenergy crops

    SciTech Connect

    Wei, Hui; Brunecky, Roman; Donohoe, Bryon S.; Ding, Shi -You; Ciesielski, Peter N.; Yang, Shihui; Tucker, Melvin P.; Himmel, Michael E.

    2015-05-13

    Identifying the cell wall-ionically bound glycoside hydrolases (GHs) in Arabidopsis stems is important for understanding the regulation of cell wall integrity. For cell wall proteomics studies, the preparation of clean cell wall fractions is a challenge since cell walls constitute an open compartment, which is more likely to contain a mixture of intracellular and extracellular proteins due to cell leakage at the late growth stage. Here, for this study, we utilize a CaCl2-extraction procedure to isolate non-structural proteins from Arabidopsis whole stems, followed by the in-solution and in-gel digestion methods coupled with Nano-LC-MS/MS, bioinformatics and literature analyses. This has led to the identification of 75 proteins identified using the in-solution method and 236 proteins identified by the in-gel method, among which about 10% of proteins predicted to be secreted. Together, eight cell wall proteins, namely AT1G75040, AT5G26000, AT3G57260, AT4G21650, AT3G52960, AT3G49120, AT5G49360, and AT3G14067, were identified by the in-solution method; among them, three were the GHs (AT5G26000, myrosinase 1, GH1; AT3G57260, β-1,3-glucanase 2, GH17; AT5G49360, bifunctional XYL 1/α-L-arabinofuranosidase, GH3). Moreover, four more GHs: AT4G30270 (xyloglucan endotransferase, GH16), AT1G68560 (bifunctional α-l-arabinofuranosidase/XYL, GH31), AT1G12240 (invertase, GH32) and AT2G28470 (β-galactosidase 8, GH35), were identified by the in-gel solution method only. Notably, more than half of above identified GHs are xylan- or hemicellulose-modifying enzymes, and will likely have an impact on cellulose accessibility, which is a critical factor for downstream enzymatic hydrolysis of plant tissues for biofuels production. Finally, the implications of these cell wall proteins identified at the late growth stage for the genetic engineering of bioenergy crops are discussed.

  8. Identifying the ionically bound cell wall and intracellular glycoside hydrolases in late growth stage Arabidopsis stems: implications for the genetic engineering of bioenergy crops

    PubMed Central

    Wei, Hui; Brunecky, Roman; Donohoe, Bryon S.; Ding, Shi-You; Ciesielski, Peter N.; Yang, Shihui; Tucker, Melvin P.; Himmel, Michael E.

    2015-01-01

    Identifying the cell wall-ionically bound glycoside hydrolases (GHs) in Arabidopsis stems is important for understanding the regulation of cell wall integrity. For cell wall proteomics studies, the preparation of clean cell wall fractions is a challenge since cell walls constitute an open compartment, which is more likely to contain a mixture of intracellular and extracellular proteins due to cell leakage at the late growth stage. Here, we utilize a CaCl2-extraction procedure to isolate non-structural proteins from Arabidopsis whole stems, followed by the in-solution and in-gel digestion methods coupled with Nano-LC-MS/MS, bioinformatics and literature analyses. This has led to the identification of 75 proteins identified using the in-solution method and 236 proteins identified by the in-gel method, among which about 10% of proteins predicted to be secreted. Together, eight cell wall proteins, namely AT1G75040, AT5G26000, AT3G57260, AT4G21650, AT3G52960, AT3G49120, AT5G49360, and AT3G14067, were identified by the in-solution method; among them, three were the GHs (AT5G26000, myrosinase 1, GH1; AT3G57260, β-1,3-glucanase 2, GH17; AT5G49360, bifunctional XYL 1/α-L-arabinofuranosidase, GH3). Moreover, four more GHs: AT4G30270 (xyloglucan endotransferase, GH16), AT1G68560 (bifunctional α-l-arabinofuranosidase/XYL, GH31), AT1G12240 (invertase, GH32) and AT2G28470 (β-galactosidase 8, GH35), were identified by the in-gel solution method only. Notably, more than half of above identified GHs are xylan- or hemicellulose-modifying enzymes, and will likely have an impact on cellulose accessibility, which is a critical factor for downstream enzymatic hydrolysis of plant tissues for biofuels production. The implications of these cell wall proteins identified at the late growth stage for the genetic engineering of bioenergy crops are discussed. PMID:26029221

  9. Ionic Strength Sensing in Living Cells.

    PubMed

    Liu, Boqun; Poolman, Bert; Boersma, Arnold J

    2017-09-06

    Knowledge of the ionic strength in cells is required to understand the in vivo biochemistry of the charged biomacromolecules. Here, we present the first sensors to determine the ionic strength in living cells, by designing protein probes based on Förster resonance energy transfer (FRET). These probes allow observation of spatiotemporal changes in the ionic strength on the single-cell level.

  10. Cell Wall Proteome in the Maize Primary Root Elongation Zone. II. Region-Specific Changes in Water Soluble and Lightly Ionically Bound Proteins under Water Deficit1[W][OA

    PubMed Central

    Zhu, Jinming; Alvarez, Sophie; Marsh, Ellen L.; LeNoble, Mary E.; Cho, In-Jeong; Sivaguru, Mayandi; Chen, Sixue; Nguyen, Henry T.; Wu, Yajun; Schachtman, Daniel P.; Sharp, Robert E.

    2007-01-01

    Previous work on the adaptation of maize (Zea mays) primary roots to water deficit showed that cell elongation is maintained preferentially toward the apex, and that this response involves modification of cell wall extension properties. To gain a comprehensive understanding of how cell wall protein (CWP) composition changes in association with the differential growth responses to water deficit in different regions of the elongation zone, a proteomics approach was used to examine water soluble and loosely ionically bound CWPs. The results revealed major and predominantly region-specific changes in protein profiles between well-watered and water-stressed roots. In total, 152 water deficit-responsive proteins were identified and categorized into five groups based on their potential function in the cell wall: reactive oxygen species (ROS) metabolism, defense and detoxification, hydrolases, carbohydrate metabolism, and other/unknown. The results indicate that stress-induced changes in CWPs involve multiple processes that are likely to regulate the response of cell elongation. In particular, the changes in protein abundance related to ROS metabolism predicted an increase in apoplastic ROS production in the apical region of the elongation zone of water-stressed roots. This was verified by quantification of hydrogen peroxide content in extracted apoplastic fluid and by in situ imaging of apoplastic ROS levels. This response could contribute directly to the enhancement of wall loosening in this region. This large-scale proteomic analysis provides novel insights into the complexity of mechanisms that regulate root growth under water deficit conditions and highlights the spatial differences in CWP composition in the root elongation zone. PMID:17951457

  11. Cell wall bound anionic peroxidases from asparagus byproducts.

    PubMed

    Jaramillo-Carmona, Sara; López, Sergio; Vazquez-Castilla, Sara; Jimenez-Araujo, Ana; Rodriguez-Arcos, Rocio; Guillen-Bejarano, Rafael

    2014-10-08

    Asparagus byproducts are a good source of cationic soluble peroxidases (CAP) useful for the bioremediation of phenol-contaminated wastewaters. In this study, cell wall bound peroxidases (POD) from the same byproducts have been purified and characterized. The covalent forms of POD represent >90% of the total cell wall bound POD. Isoelectric focusing showed that whereas the covalent fraction is constituted primarily by anionic isoenzymes, the ionic fraction is a mixture of anionic, neutral, and cationic isoenzymes. Covalently bound peroxidases were purified by means of ion exchange chromatography and affinity chromatography. In vitro detoxification studies showed that although CAP are more effective for the removal of 4-CP and 2,4-DCP, anionic asparagus peroxidase (AAP) is a better option for the removal of hydroxytyrosol (HT), the main phenol present in olive mill wastewaters.

  12. Transfer of copper and zinc from ionic and metallothionein-bound forms to Cu, Zn--superoxide dismutase.

    PubMed

    Suzuki, K T; Kuroda, T

    1995-03-01

    Reactivity in transfer of copper (Cu) and zinc (Zn) to their binding sites of superoxide dismutase (SOD) was examined in vitro by the HPLC/atomic absorption spectrophotometry. Ionic Cu (cuprous and cupric ions) were incorporated more efficiently than the metal bound to metallothionein. Cu binds not only to the Cu-binding site but also to the Zn-binding site. Although Zn in the reaction medium and the metal bound to the Zn-binding site of SOD affected little the reactivity in binding of ionic Cu, they disturbed the reactivity of Cu bound to metallothionein to the Cu-binding site. Both ionic and metallothionein-bound Zn were transferred at a comparable efficiency to the Zn-binding site but not to the Cu-binding site. Co-existing ionic Cu but not metallothionein-bound Cu in the medium inhibited the binding of Zn to SOD. The results indicate that ionic Cu can be transferred to both Cu- and Zn-binding sites of SOD more efficiently than metallothionein-bound Cu, while both ionic and metallothionein-bound Zn are transferred only to Zn-binding site at a comparable efficiency.

  13. Ionic mechanisms in pancreatic β cell signaling.

    PubMed

    Yang, Shao-Nian; Shi, Yue; Yang, Guang; Li, Yuxin; Yu, Jia; Berggren, Per-Olof

    2014-11-01

    The function and survival of pancreatic β cells critically rely on complex electrical signaling systems composed of a series of ionic events, namely fluxes of K(+), Na(+), Ca(2+) and Cl(-) across the β cell membranes. These electrical signaling systems not only sense events occurring in the extracellular space and intracellular milieu of pancreatic islet cells, but also control different β cell activities, most notably glucose-stimulated insulin secretion. Three major ion fluxes including K(+) efflux through ATP-sensitive K(+) (KATP) channels, the voltage-gated Ca(2+) (CaV) channel-mediated Ca(2+) influx and K(+) efflux through voltage-gated K(+) (KV) channels operate in the β cell. These ion fluxes set the resting membrane potential and the shape, rate and pattern of firing of action potentials under different metabolic conditions. The KATP channel-mediated K(+) efflux determines the resting membrane potential and keeps the excitability of the β cell at low levels. Ca(2+) influx through CaV1 channels, a major type of β cell CaV channels, causes the upstroke or depolarization phase of the action potential and regulates a wide range of β cell functions including the most elementary β cell function, insulin secretion. K(+) efflux mediated by KV2.1 delayed rectifier K(+) channels, a predominant form of β cell KV channels, brings about the downstroke or repolarization phase of the action potential, which acts as a brake for insulin secretion owing to shutting down the CaV channel-mediated Ca(2+) entry. These three ion channel-mediated ion fluxes are the most important ionic events in β cell signaling. This review concisely discusses various ionic mechanisms in β cell signaling and highlights KATP channel-, CaV1 channel- and KV2.1 channel-mediated ion fluxes.

  14. Ionic liquid electrolytes for dye-sensitized solar cells.

    PubMed

    Gorlov, Mikhail; Kloo, Lars

    2008-05-28

    The potential of room-temperature molten salts (ionic liquids) as solvents for electrolytes for dye-sensitized solar cells has been investigated during the last decade. The non-volatility, good solvent properties and high electrochemical stability of ionic liquids make them attractive solvents in contrast to volatile organic solvents. Despite this, the relatively high viscosity of ionic liquids leads to mass-transport limitations. Here we review recent developments in the application of different ionic liquids as solvents or components of liquid and quasi-solid electrolytes for dye-sensitized solar cells.

  15. Ionic conductors for solid oxide fuel cells

    DOEpatents

    Krumpelt, Michael; Bloom, Ira D.; Pullockaran, Jose D.; Myles, Kevin M.

    1993-01-01

    An electrolyte that operates at temperatures ranging from 600.degree. C. to 800.degree. C. is provided. The electrolyte conducts charge ionically as well as electronically. The ionic conductors include molecular framework structures having planes or channels large enough to transport oxides or hydrated protons and having net-positive or net-negative charges. Representative molecular framework structures include substituted aluminum phosphates, orthosilicates, silicoaluminates, cordierites, apatites, sodalites, and hollandites.

  16. Ionic conductors for solid oxide fuel cells

    SciTech Connect

    Krumpelt, M.; Bloom, I.D.; Pullockaran, J.D.; Myles, K.M.

    1991-12-31

    An electrolyte that operates at temperatures ranging from 600{degree}C to 800{degree}C is discussed. The electrolyte conducts charge ionically as well as electronically. The ionic conductors include molecular framework structures having planes or channels large enough to transport oxides or hydrated protons and having net-positive or net-negative charges. Representative molecular framework structures include substituted aluminum phosphates, orthosilicates, silicoaluminates, cordierites, apatites, sodalites, and hollandites.

  17. Comparative biochemical characterization of peroxidases (class III) tightly bound to the maize root cell walls and modulation of the enzyme properties as a result of covalent binding.

    PubMed

    Hadži-Tašković Šukalović, Vesna; Vuletić, Mirjana; Marković, Ksenija; Cvetić Antić, Tijana; Vučinić, Željko

    2015-01-01

    Comparative biochemical characterization of class III peroxidase activity tightly bound to the cell walls of maize roots was performed. Ionically bound proteins were solubilized from isolated walls by salt washing, and the remaining covalently bound peroxidases were released, either by enzymatic digestion or by a novel alkaline extraction procedure that released covalently bound alkali-resistant peroxidase enzyme. Solubilized fractions, as well as the salt-washed cell wall fragments containing covalently bound proteins, were analyzed for peroxidase activity. Peroxidative and oxidative activities indicated that peroxidase enzymes were predominately associated with walls by ionic interactions, and this fraction differs from the covalently bound one according to molecular weight, isozyme patterns, and biochemical parameters. The effect of covalent binding was evaluated by comparison of the catalytic properties of the enzyme bound to the salt-washed cell wall fragments with the corresponding solubilized and released enzyme. Higher thermal stability, improved resistance to KCN, increased susceptibility to H2O2, stimulated capacity of wall-bound enzyme to oxidize indole-3-acetic acid (IAA) as well as the difference in kinetic parameters between free and bound enzymes point to conformational changes due to covalent binding. Differences in biochemical properties of ionically and covalently bound peroxidases, as well as the modulation of the enzyme properties as a result of covalent binding to the walls, indicate that these two fractions of apoplastic peroxidases play different roles.

  18. Effect of dissolved oxygen on nitrogen fixation by A. vinelandii. II. Ionically adsorbed cells.

    PubMed

    Diluccio, R C; Kirwan, D J

    1984-01-01

    Continuous culture studies of Azotobacter vinelandii cells immobilized by ionic adsorption to Cellex E anion exchange resin were conducted under oxygen-limited conditions for comparison to free-cell cultures. Immobilization had little effect upon the specific respiration and sucrose consumption rates as compared to free cells. However, maxima in specific nitrogen fixation rate and nitrogenase activity as a function of dissolved oxygen occurred at a C(O(2) ) value of approximately 0.005 mM as opposed to 0.02 mM for free cells. Further, in contrast to free-cell culture, most of the fixed nitrogen appeared in the medium rather than within intact cells. There were strong indications that reproduction of bound cells often resulted in cell lysis accounting for the fixed nitrogen content in solution.

  19. Ionic currents in single isolated bullfrog atrial cells

    PubMed Central

    1983-01-01

    Enzymatic dispersion has been used to yield single cells from segments of bullfrog atrium. Previous data (Hume and Giles, 1981) have shown that these individual cells are quiescent and have normal resting potentials and action potentials. The minimum DC space constant is approximately 920 microns. The major goals of the present study were: (a) to develop and refine techniques for making quantitative measurements of the transmembrane ionic currents, and (b) to identify the individual components of ionic current which generate different phases of the action potential. Initial voltage-clamp experiments made using a conventional two-microelectrode technique revealed a small tetrodotoxin (TTX)-insensitive inward current. The small size of this current (2.5-3.0 X 10(-10)A) and the technical difficulty of the two- microelectrode experiments prompted the development of a one- microelectrode voltage-clamp technique which requires impalements using a low-resistance (0.5-2 M omega) micropipette. Voltage-clamp experiments using this new technique in isolated single atrial cells reveal five distinct ionic currents: (a) a conventional transient Na+ current, (b) a TTX-resistant transient inward current, carried mainly by Ca++, (c) a component of persistent inward current, (d) a slowly developing outward K+ current, and (e) an inwardly rectifying time- independent background current. The single suction micropipette technique appears well-suited for use in the quantitative study of ionic currents in these cardiac cells, and in other small cells having similar electrophysiological properties. PMID:6302197

  20. Ionic channel changes in glaucomatous retinal ganglion cells: multicompartment modeling.

    PubMed

    Maturana, Matias I; Turpin, Andrew; McKendrick, Allison M; Kameneva, Tatiana

    2014-01-01

    This research takes a step towards discovering underlying ionic channel changes in the glaucomatous ganglion cells. Glaucoma is characterized by a gradual death of retinal ganglion cells. In this paper, we propose a hypothesis that the ionic channel concentrations change during the progression of glaucoma. We use computer simulation of a multi-compartment morphologically correct model of a mouse retinal ganglion cell to verify our hypothesis. Using published experimental data, we alter the morphology of healthy ganglion cells to replicate glaucomatous cells. Our results suggest that in glaucomatous cell, the sodium channel concentration decreases in the soma by 30% and by 60% in the dendrites, calcium channel concentration decreases by 10% in all compartments, and leak channel concentration increases by 40% in the soma and by 100% in the dendrites.

  1. Identification and characterization of cell-bound membrane vesicles.

    PubMed

    Tang, Qisheng; Zhang, Xiaojun; Zhang, Wendiao; Zhao, Siyuan; Chen, Yong

    2017-05-01

    In contrast to the released/circulating membrane vesicles (extracellular vesicles), cell-bound membrane vesicles are poorly identified and characterized. In this study, cell-bound membrane vesicles on human umbilical vein endothelial cells (HUVECs) and human hepatoma HepG-2 cells were investigated. We identified that cell-bound membrane vesicles are not co-localized with the major markers for extracellular vesicles (e.g. phosphatidylserine, CD63, CD107α, CD31, and DNA fragments for the three well-known types of extracellular vesicles) and for intracellular organelles with similar sizes (e.g. MitoTracker and LAMP1/LAMP3 for mitochondria and multivesicular bodies or lysosomes, respectively). The data imply that cell-bound membrane vesicles are neither the precursors of extracellular vesicles nor a false structure pushed up by an intracellular organelle but probably a novel unknown structure in the plasma membrane. Moreover, we revealed that cell-bound membrane vesicles are resistant to various detergents including but probably not limited to Triton X-100, SDS, and saponin. We further characterized that these unique vesicles are soluble in organic solvents (e.g. chloroform-methanol mixture and ethanol) which can be prevented by a lipid-stabilizing fixative (e.g. OsO4) and that they are co-localized with, but do not monopolize, the major markers (e.g. caveolin-1 and GM1) for lipid rafts (a nano-sized detergent-resistant domains in the plasma membrane). The data imply that cell-bound membrane vesicles contain the lipid component and lipid rafts. Involvement of other specific unknown components might explain the detergent resistance of cell-bound membrane vesicles. Further research will mainly depend on the establishment of an effective approach for isolation/purification of these vesicles from the plasma membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Proteomics of loosely bound cell wall proteins of Arabidopsis thaliana cell suspension cultures: a critical analysis.

    PubMed

    Borderies, Gisèle; Jamet, Elisabeth; Lafitte, Claude; Rossignol, Michel; Jauneau, Alain; Boudart, Georges; Monsarrat, Bernard; Esquerré-Tugayé, Marie-Thérèse; Boudet, Alain; Pont-Lezica, Rafael

    2003-10-01

    The complete sequencing of the Arabidopsis thaliana genome allows the use of the recently developed mass spectrometry techniques to identify the cell wall proteins (CWPs). Most proteomic approaches depend on the quality of sample preparation. Extraction of CWPs is particularly complex since the proteins may be free in the apoplast or are embedded in a polysaccharide matrix where they are retained by Van der Waals interactions, hydrogen bonds, hydrophobic or ionic interactions, or cross-linked by covalent bonds. Specific and sequential extraction procedures thus need to be developed. We report on the sequential extraction of loosely bound CWPs from living A. thaliana cells in culture. Different salts and chelating agents were used for releasing the proteins from the wall. Their effects on the extraction of CWPs and on the integrity of the plasma membrane were evaluated. Bioinformatic software was used to identify proteins and to predict their sub-cellular localization. The obtained data show that the plasma membrane of cells in culture was easily damaged by some steps of the extraction procedure, leading to the release of increasing amounts of intracellular proteins. Nevertheless, we identified fifty CWPs among which thirteen were new proteins for the cell wall. In addition, 76% of these CWPs were basic proteins not resolved in two-dimensional (2-D) gel electrophoresis. The existence of two hypothetical proteins was confirmed. The structure of three proteins could be confirmed using mass spectrometry data.

  3. Combined calcium fluorescence recording with ionic currents in contractile cells.

    PubMed

    Rainbow, Richard D

    2013-01-01

    Measurement of calcium (Ca(2+)) fluorescence in conjunction with ionic currents is of particular importance in contractile cells, such as cardiac ventricular myocytes and vascular smooth muscle. The interplay between membrane potential and intracellular calcium ([Ca(2+)](i)) is fundamental to the regulation of contractile function and cell signalling. Here the loading of cells either with an esterified fluorescence indicator prior to patch clamp recording, or dye loading via the patch pipette with "free" indicator, is described to allow simultaneous measurement of fluorescence and electrical signals.

  4. Ionic currents in crustacean neurosecretory cells.

    PubMed

    Onetti, C G; García, U; Valdiosera, R F; Aréchiga, H

    1990-11-01

    1. The patterns of electrical activity and membrane characteristics of a population of neurosecretory-cell somata in the X-organ of the crayfish were investigated with microelectrodes and whole-cell, voltage-clamp techniques. Some neurons (56%) were silent but could be excited by intracellular current injection: other cells showed spontaneous tonic activity (35%), and some had spontaneous bursting activity (9%). The spiking activity was abolished by tetrodotoxin (TTX) exposure and by severing the axon near the cell body. After axotomy, only a small, slow, regenerative depolarization remained that could be blocked by Cd2+. 2. Under voltage clamp the steady-state I-V curve in low [Ca2+]i (9 X 10(-9) M) showed a slope conductance of 16.7 +/- 3.9 (SD) nS (n = 10) at -50 mV and zero current potential of -50.1 +/- 7.7 mV. In current-clamp mode these neurons were either silent or fired tonically. With high [Ca2+]i (1.7 X 10(-6) M) both the slope conductance and inward and outward currents were reduced. In some neurons high [Ca2+]i reveals a negative slope resistance in the range of -46 to -41 mV. It could be supressed by removing [Na+]o, but it was TTX insensitive. These are the neurons that under current clamp showed bursting activity. 3. The main inward current in cell somata was a Ca2+ current of 2 +/- 0.6 nA (n = 18), activated at -40 mV and peaking at 20 mV. It showed relaxation with prolonged pulses. No Na(+)-dependent, TTX-sensitive inward currents were recorded with short (100-ms) pulses in axotomized neurons. 4. Two outward currents could be distinguished.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. The cell-bound α-amylases of Streptococcus bovis

    PubMed Central

    Walker, Gwen J.

    1965-01-01

    1. The cell-bound α-amylase of Streptococcus bovis has been isolated from other carbohydrases in the cell extract by chromatography on DEAE-cellulose. The enzyme has been compared with the extracellular α-amylase produced by this organism. 2. The two amylases had similar action patterns on amylose, the main product being maltotriose with smaller amounts of maltose and a little glucose. 3. The cell-bound amylase hydrolysed maltopentaose and maltohexaose at a similar rate to the hydrolysis of amylose. Maltotetraose was hydrolysed six times more slowly, and maltotriose 280 times more slowly, than amylose. 4. Studies with end-labelled maltodextrins revealed that the cell-bound α-amylase preferentially hydrolysed the third linkage from the non-reducing end, liberating maltotriose. The linkage at the reducing end of maltotriose was more easily hydrolysed than the other. 5. Egg-white lysozyme and the extracellular enzymes of Streptomyces albus lysed the cell walls of Streptococcus bovis, releasing amylase into the medium. In the presence of 0·6 m-sucrose 10% of the maximal amylase activity was released by lysozyme. Suspension of the spheroplasts in dilute buffer caused the rupture of the cytoplasmic membrane and the liberation of amylase. 6. A sensitive method for determining the ability of amylases to degrade starch granules is described. PMID:14346085

  6. Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Belieres, Jean-Philippe

    2004-01-01

    There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research

  7. Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Belieres, Jean-Philippe

    2004-01-01

    There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research

  8. Argonaute and Argonaute-Bound Small RNAs in Stem Cells

    PubMed Central

    Zhai, Lihong; Wang, Lin; Teng, Feng; Zhou, Lanting; Zhang, Wenjing; Xiao, Juan; Liu, Ying; Deng, Wenbin

    2016-01-01

    Small RNAs are essential for a variety of cellular functions. Argonaute (AGO) proteins are associated with all of the different classes of small RNAs, and are indispensable in small RNA-mediated regulatory pathways. AGO proteins have been identified in various types of stem cells in diverse species from plants and animals. This review article highlights recent progress on how AGO proteins and AGO-bound small RNAs regulate the self-renewal and differentiation of distinct stem cell types, including pluripotent, germline, somatic, and cancer stem cells. PMID:26861290

  9. How Uncertainty Bounds the Shape Index of Simple Cells

    PubMed Central

    2014-01-01

    We propose a theoretical motivation to quantify actual physiological features, such as the shape index distributions measured by Jones and Palmer in cats and by Ringach in macaque monkeys. We will adopt the uncertainty principle associated to the task of detection of position and orientation as the main tool to provide quantitative bounds on the family of simple cells concretely implemented in primary visual cortex. Mathematics Subject Classification (2000)2010: 62P10, 43A32, 81R15. PMID:24742044

  10. Aluminum stimulates uptake of non-transferrin bound iron and transferrin bound iron in human glial cells.

    PubMed

    Kim, Yongbae; Olivi, Luisa; Cheong, Jae Hoon; Maertens, Alex; Bressler, Joseph P

    2007-05-01

    Aluminum and other trivalent metals were shown to stimulate uptake of transferrin bound iron and nontransferrin bound iron in erytholeukemia and hepatoma cells. Because of the association between aluminum and Alzheimer's Disease, and findings of higher levels of iron in Alzheimer's disease brains, the effects of aluminum on iron homeostasis were examined in a human glial cell line. Aluminum stimulated dose- and time-dependent uptake of nontransferrin bound iron and iron bound to transferrin. A transporter was likely involved in the uptake of nontransferrin iron because uptake reached saturation, was temperature-dependent, and attenuated by inhibitors of protein synthesis. Interestingly, the effects of aluminum were not blocked by inhibitors of RNA synthesis. Aluminum also decreased the amount of iron bound to ferritin though it did not affect levels of divalent metal transporter 1. These results suggest that aluminum disrupts iron homeostasis in the brain by several mechanisms including the transferrin receptor, a nontransferrin iron transporter, and ferritin.

  11. Aluminum stimulates uptake of non-transferrin bound iron and transferrin bound iron in human glial cells

    SciTech Connect

    Kim, Yongbae; Olivi, Luisa; Cheong, Jae Hoon; Maertens, Alex; Bressler, Joseph P. . E-mail: Bressler@kennedykrieger.org

    2007-05-01

    Aluminum and other trivalent metals were shown to stimulate uptake of transferrin bound iron and nontransferrin bound iron in erytholeukemia and hepatoma cells. Because of the association between aluminum and Alzheimer's Disease, and findings of higher levels of iron in Alzheimer's disease brains, the effects of aluminum on iron homeostasis were examined in a human glial cell line. Aluminum stimulated dose- and time-dependent uptake of nontransferrin bound iron and iron bound to transferrin. A transporter was likely involved in the uptake of nontransferrin iron because uptake reached saturation, was temperature-dependent, and attenuated by inhibitors of protein synthesis. Interestingly, the effects of aluminum were not blocked by inhibitors of RNA synthesis. Aluminum also decreased the amount of iron bound to ferritin though it did not affect levels of divalent metal transporter 1. These results suggest that aluminum disrupts iron homeostasis in Brain by several mechanisms including the transferrin receptor, a nontransferrin iron transporter, and ferritin.

  12. Ionic transport in hybrid lead iodide perovskite solar cells

    PubMed Central

    Eames, Christopher; Frost, Jarvist M.; Barnes, Piers R. F.; O'Regan, Brian C.; Walsh, Aron; Islam, M. Saiful

    2015-01-01

    Solar cells based on organic–inorganic halide perovskites have recently shown rapidly rising power conversion efficiencies, but exhibit unusual behaviour such as current–voltage hysteresis and a low-frequency giant dielectric response. Ionic transport has been suggested to be an important factor contributing to these effects; however, the chemical origin of this transport and the mobile species are unclear. Here, the activation energies for ionic migration in methylammonium lead iodide (CH3NH3PbI3) are derived from first principles, and are compared with kinetic data extracted from the current–voltage response of a perovskite-based solar cell. We identify the microscopic transport mechanisms, and find facile vacancy-assisted migration of iodide ions with an activation energy of 0.6 eV, in good agreement with the kinetic measurements. The results of this combined computational and experimental study suggest that hybrid halide perovskites are mixed ionic–electronic conductors, a finding that has major implications for solar cell device architectures. PMID:26105623

  13. Nonhumidified intermediate temperature fuel cells using protic ionic liquids.

    PubMed

    Lee, Seung-Yul; Ogawa, Atsushi; Kanno, Michihiro; Nakamoto, Hirofumi; Yasuda, Tomohiro; Watanabe, Masayoshi

    2010-07-21

    In this paper, the characterization of a protic ionic liquid, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]), as a proton conductor for a fuel cell and the fabrication of a membrane-type fuel cell system using [dema][TfO] under nonhumidified conditions at intermediate temperatures are described in detail. In terms of physicochemical and electrochemical properties, [dema][TfO] exhibits high activity for fuel cell electrode reactions (i.e., the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR)) at a Pt electrode, and the open circuit voltage (OCV) of a liquid fuel cell is 1.03 V at 150 degrees C, as has reported in ref 27. However, diethylmethylammonium bis(trifluoromethane sulfonyl)amide ([dema][NTf(2)]) has relatively low HOR and ORR activity, and thus, the OCV is ca. 0.7 V, although [dema][NTf(2)] and [dema][TfO] have an identical cation ([dema]) and similar thermal and bulk-transport properties. Proton conduction occurs mainly via the vehicle mechanism in [dema][TfO] and the proton transference number (t(+)) is 0.5-0.6. This relatively low t(+) appears to be more disadvantageous for a proton conductor than for other electrolytes such as hydrated sulfonated polymer electrolyte membranes (t(+) = 1.0). However, fast proton-exchange reactions occur between ammonium cations and amines in a model compound. This indicates that the proton-exchange mechanism contributes to the fuel cell system under operation, where deprotonated amines are continuously generated by the cathodic reaction, and that polarization of the cell is avoided. Six-membered sulfonated polyimides in the diethylmethylammonium form exhibit excellent compatibility with [dema][TfO]. The composite membranes can be obtained up to a [dema][TfO] content of 80 wt % and exhibit good thermal stability, high ionic conductivity, and mechanical strength and gas permeation comparable to those of hydrated Nafion. H(2)/O(2) fuel cells prepared using the composite membranes can

  14. Ionic currents in isolated and in situ squid Schwann cells

    PubMed Central

    Inoue, Isao; Tsutsui, Izuo; Joan Abbott, N; Brown, Euan R

    2002-01-01

    Ionic currents from Schwann cells isolated enzymatically from the giant axons of the squids Loligo forbesi, Loligo vulgaris and Loligo bleekeri were compared with those obtained in situ. Macroscopic and single channel ionic currents were recorded using whole-cell voltage and patch clamp. In the whole-cell configuration, depolarisation from negative holding potentials evoked two voltage-dependent currents, an inward current and a delayed outward current. The outward current resembled an outwardly rectifying K+ current and was activated at −40 mV after a latent period of 5-20 ms following a step depolarisation. The current was reduced by externally applied nifedipine, Co2+ or quinine, was not blocked by addition of apamin or charibdotoxin and was insensitive to externally applied l-glutamate or acetylcholine. The voltage-gated inward current was activated at −40 mV and was identified as an L-type calcium current sensitive to externally applied nifedipine. Schwann cells were impaled in situ in split-open axons and voltage clamped using discontinuous single electrode voltage clamp. Voltage dependent outward currents were recorded that were kinetically identical to those seen in isolated cells and that had similar current-voltage relations. Single channel currents were recorded from excised inside-out patches. A single channel type was observed with a reversal potential close to the equilibrium potential for K+ (EK) and was therefore identified as a K+ channel. The channel conductance was 43.6 pS when both internal and external solutions contained 150 mm K+. Activity was weakly dependent on membrane voltage but sensitive to the internal Ca2+ concentration. Activity was insensitive to externally or internally applied l-glutamate or acetylcholine. The results suggest that calcium channels and calcium-activated K+ channels play an important role in the generation of the squid Schwann cell membrane potential, which may be controlled by the resting intracellular Ca2

  15. Metal-air cell comprising an electrolyte with a room temperature ionic liquid and hygroscopic additive

    DOEpatents

    Friesen, Cody A.; Krishnan, Ramkumar; Tang, Toni; Wolfe, Derek

    2014-08-19

    An electrochemical cell comprising an electrolyte comprising water and a hydrophobic ionic liquid comprising positive ions and negative ions. The electrochemical cell also includes an air electrode configured to absorb and reduce oxygen. A hydrophilic or hygroscopic additive modulates the hydrophobicity of the ionic liquid to maintain a concentration of the water in the electrolyte is between 0.001 mol % and 25 mol %.

  16. Pacemaker activity and ionic currents in mouse atrioventricular node cells.

    PubMed

    Marger, Laurine; Mesirca, Pietro; Alig, Jacqueline; Torrente, Angelo; Dubel, Stefan; Engeland, Birgit; Kanani, Sandra; Fontanaud, Pierre; Striessnig, Jörg; Shin, Hee-Sup; Isbrandt, Dirk; Ehmke, Heimo; Nargeot, Joël; Mangoni, Matteo E

    2011-01-01

    It is well established that Pacemaker activity of the sino-atrial node (SAN) initiates the heartbeat. However, the atrioventricular node (AVN) can generate viable pacemaker activity in case of SAN failure, but we have limited knowledge of the ionic bases of AVN automaticity. We characterized pacemaker activity and ionic currents in automatic myocytes of the mouse AVN. Pacemaking of AVN cells (AVNCs) was lower than that of SAN pacemaker cells (SANCs), both in control conditions and upon perfusion of isoproterenol (ISO). Block of I(Na) by tetrodotoxin (TTX) or of I(Ca,L) by isradipine abolished AVNCs pacemaker activity. TTX-resistant (I(Nar)) and TTX-sensitive (I(Nas)) Na(+) currents were recorded in mouse AVNCs, as well as T-(I(Ca,T)) and L-type (I(Ca,L)) Ca(2+) currents I(Ca,L) density was lower than in SANCs (51%). The density of the hyperpolarization-activated current, (I(f)) and that of the fast component of the delayed rectifier current (I(Kr)) were, respectively, lower (52%) and higher (53%) in AVNCs than in SANCs. Pharmacological inhibition of I(f) by 3 µM ZD-7228 reduced pacemaker activity by 16%, suggesting a relevant role for I(f) in AVNCs automaticity. Some AVNCs expressed also moderate densities of the transient outward K(+) current (I(to)). In contrast, no detectable slow component of the delayed rectifier current (I(Ks)) could be recorded in AVNCs. The lower densities of I(f) and I(Ca,L), as well as higher expression of I(Kr) in AVNCs than in SANCs may contribute to the intrinsically slower AVNCs pacemaking than that of SANCs.

  17. Ionic mechanisms of autorhythmic firing in rat cerebellar Golgi cells

    PubMed Central

    Elisabetta Cesana, Lia Forti; Mapelli, Jonathan; D'Angelo, Egidio

    2006-01-01

    Although Golgi cells (GoCs), the main type of inhibitory interneuron in the cerebellar granular layer (GL), are thought to play a central role in cerebellar network function, their excitable properties have remained unexplored. GoCs fire rhythmically in vivo and in slices, but it was unclear whether this activity originated from pacemaker ionic mechanisms. We explored this issue in acute cerebellar slices from 3-week-old rats by combining loose cell-attached (LCA) and whole-cell (WC) recordings. GoCs displayed spontaneous firing at 1–10 Hz (room temperature) and 2–20 Hz (35–37°C), which persisted in the presence of blockers of fast synaptic receptors and mGluR and GABAB receptors, thus behaving, in our conditions, as pacemaker neurons. ZD 7288 (20 μm), a potent hyperpolarization-activated current (Ih) blocker, slowed down pacemaker frequency. The role of subthreshold Na+ currents (INa,sub) could not be tested directly, but we observed a robust TTX-sensitive, non-inactivating Na+ current in the subthreshold voltage range. When studying repolarizing currents, we found that retigabine (5 μm), an activator of KCNQ K+ channels generating neuronal M-type K+ (IM) currents, reduced GoC excitability in the threshold region. The KCNQ channel antagonist XE991 (5 μm) did not modify firing, suggesting that GoC IM has low XE991 sensitivity. Spike repolarization was followed by an after-hyperpolarization (AHP) supported by apamin-sensitive Ca2+-dependent K+ currents (Iapa). Block of Iapa decreased pacemaker precision without altering average frequency. We propose that feed-forward depolarization is sustained by Ih and INa,sub, and that delayed repolarizing feedback involves an IM-like current whose properties remain to be characterized. The multiple ionic mechanisms shown here to contribute to GoC pacemaking should provide the substrate for fine regulation of firing frequency and precision, thus influencing the cyclic inhibition exerted by GoCs onto the cerebellar GL

  18. ALUMINUM STIMULATES UPTAKE OF NON-TRANSFERRIN BOUND IRON AND TRANSFERRIN BOUND IRON IN HUMAN GLIAL CELLS

    PubMed Central

    Kim, Yongbae; Olivi, Luisa; Cheong, Jae Hoon; Maertens, Alex; Bressler, Joseph P.

    2011-01-01

    Aluminum and other trivalent metals were shown to stimulate uptake of transferrin bound iron and nontransferrin bound iron in erytholeukemia and hepatoma cells. Because of the association between aluminum and Alzheimer’s Disease, and findings of higher levels of iron in Alzheimer’s disease brains, the effects of aluminum on iron homeostasis were examined in a human glial cell line. Aluminum stimulated dose- and time-dependent uptake of nontransferrin bound iron and iron bound to transferrin. A transporter was likely involved in the uptake of nontransferrin iron because uptake reached saturation, was temperature-dependent, and attenuated by inhibitors of protein synthesis. Interestingly, the effects of aluminum were not blocked by inhibitors of RNA synthesis. Aluminum also decreased the amount of iron bound to ferritin though it did not affect levels of divalent metal transporter 1. These results suggest that aluminum disrupts iron homeostasis in the brain by several mechanisms including the transferrin receptor, a nontransferrin iron transporter, and ferritin. PMID:17376497

  19. Wake-Bound-Electron Contribution to Convoy-Electron Velocity Distributions: The Effect of the Ionic Field

    NASA Astrophysics Data System (ADS)

    Day, Michael H.

    1980-03-01

    In the sudden approximation for surface penetration, a wake-bound electron emerges into vacuum with no net velocity relative to the ion it follows. After exit, the wake electron and ion interact via Coulomb attraction which introduces diffraction structure in the projectile-frame electron velocity distribution. Modeling of the detection process is done in order to compare with experimental results.

  20. Proteomics of weakly bound cell wall proteins in rice calli.

    PubMed

    Chen, Xiong-Yan; Kim, Sun Tae; Cho, Won Kyong; Rim, Yeonggil; Kim, Suwha; Kim, Seon-Won; Kang, Kyu Young; Park, Zee Yong; Kim, Jae-Yean

    2009-05-01

    In the present work, we present a proteomic analysis of weakly bound cell wall proteins (CWPs) in rice. CWPs from rice calli were extracted with mannitol/CaCl(2), followed by back extraction with water-saturated phenol. The isolated CWPs were evaluated for contamination by cytosolic proteins by measuring the enzymatic activity of an intracellular marker (glucose-6-phosphate dehydrogenase). This revealed the presence of low levels of intracellular proteins and a significant enrichment of CWPs, as compared to the total extract. Protein samples were digested in gels with trypsin and analyzed using the multidimensional protein identification technology (MudPIT). A total of 292 proteins were identified, which included numerous classical CWPs and antioxidant proteins. Bioinformatics analysis showed that 72.6% of these proteins possessed a signal peptide, and a total of 198 proteins were determined to be CWPs in rice. Functional classification divided the extracellular proteins into different groups, including glycosyl hydrolases (23%), antioxidant proteins (12%), cell wall structure-related proteins (6%), metabolic pathways (9%), protein modifications (4%), defense (4%), and protease inhibitors (3%). Furthermore, comparative analysis of our identified rice CWPs with known Arabidopsis CWPs revealed 25 novel rice-specific CWPs. The study described here is an unprecedented large-scale analysis of CWPs in rice.

  1. Transfer of a weakly bound electron in collisions of Rydberg atoms with neutral particles. I. Long-range interaction effects in the ionic-covalent coupling

    SciTech Connect

    Lebedev, V. S. Narits, A. A.

    2013-10-15

    Ion-pair formation processes are studied in collisions of Rydberg atoms with neutral particles possessing small electron affinities. Nonadiabatic transitions from a Rydberg covalent term to an ionic term of a quasi-molecule are considered using the modified Landau-Zener theory supplemented with calculation of survival factors of an anion decaying in the Coulomb field of a positive ion core. Using the technique of irreducible tensor operators and the momentum representation of the wavefunction of a highly excited atom, exact expressions are obtained for transition matrix elements and the ionic-covalent coupling parameter. The approach developed in the paper provides the description beyond the scope of a conventional assumption about a small variation of the wavefunction of the Rydberg atom on the range of electron coordinates determined by the characteristic radius of the wavefunction of the anion. This allows one to correctly consider long-range effects of the interaction between a weakly bound electron and the neutral core of a negative ion in processes under study. It is shown by the example of thermal collisions of Xe(nf) atoms with CH{sub 3}CN molecules that this is very important for a reliable quantitative description of anion formation with a low binding energy. The results are compared with experiments and calculations performed within the framework of a number of approximate methods.

  2. Cell wall-bound cationic and anionic class III isoperoxidases of pea root: biochemical characterization and function in root growth

    PubMed Central

    Lüthje, Sabine

    2012-01-01

    Cell wall isolated from pea roots was used to separate and characterize two fractions possessing class III peroxidase activity: (i) ionically bound proteins and (ii) covalently bound proteins. Modified SDS–PAGE separated peroxidase isoforms by their apparent molecular weights: four bands of 56, 46, 44, and 41kDa were found in the ionically bound fraction (iPOD) and one band (70kDa) was resolved after treatment of the cell wall with cellulase and pectinase (cPOD). Isoelectric focusing (IEF) patterns for iPODs and cPODs were significantly different: five iPODs with highly cationic pI (9.5–9.2) were detected, whereas the nine cPODs were anionic with pI values between pH 3.7 and 5. iPODs and cPODs showed rather specific substrate affinity and different sensitivity to inhibitors, heat, and deglycosylation treatments. Peroxidase and oxidase activities and their IEF patterns for both fractions were determined in different zones along the root and in roots of different ages. New iPODs with pI 9.34 and 9.5 were induced with root growth, while the activity of cPODs was more related to the formation of the cell wall in non-elongating tissue. Treatment with auxin that inhibits root growth led to suppression of iPOD and induction of cPOD. A similar effect was obtained with the widely used elicitor, chitosan, which also induced cPODs with pI 5.3 and 5.7, which may be specifically related to pathogen defence. The differences reported here between biochemical properties of cPOD and iPOD and their differential induction during development and under specific treatments implicate that they are involved in specific and different physiological processes. Abbreviations:cPODcovalently bound peroxidaseDAB3,3'-diaminobenzidineDEPMPOspin-trap (5-diethoxy-phosphoryl-5-methyl-1-pyrroline-n-oxide)EPRelectron paramagnetic resonanceHRPhorseradish peroxidaseIAAindole-3-acetic acidHRPhorseradish peroxidaseIEFisoelectric focusingiPODionically bound peroxidaseNAAnaphthalene acetic acid

  3. Intranasal M cell uptake of nanoparticles is independently influenced by targeting ligands and buffer ionic strength.

    PubMed

    Rajapaksa, Thejani E; Bennett, Kaila M; Hamer, Mary; Lytle, Christian; Rodgers, Victor G J; Lo, David D

    2010-07-30

    In mucosal tissues, epithelial M cells capture and transport microbes across the barrier to underlying immune cells. Previous studies suggested that high affinity ligands targeting M cells may be used to deliver mucosal vaccines; here, we show that particle composition and dispersion buffer ionic strength can independently influence their uptake in vivo. First, addition of a poloxamer 188 to nanoparticle formulations increased uptake of intranasally administered nanoparticles in vivo, but the effect was dependent on the presence of the M cell-targeting ligand. Second, solvent ionic strength is known to effect electrostatic interactions; accordingly, reduced ionic strength increased the electrostatic potential between the epithelium and the particles. Interestingly, below a critical ionic strength, intranasal particle uptake in vivo significantly was increased even when controlled for osmolarity. Similar results were obtained for uptake of bacterial particles. Surprisingly, at low ionic strength, the specific enhancement effect by the targeting peptide was negligible. Modeling of the electrostatic forces predicted that the enhancing effects of the M cell-targeting ligand only are enabled at high ionic strength, as particle electrostatic forces are reduced through Debye screening. Thus, electrostatic forces can have a dramatic effect on the in vivo M cell particle uptake independent of the action of targeting ligands. Examination of these forces will be helpful to optimizing mucosal vaccine and drug delivery.

  4. Cells labeled with multiple fluorophores bound to a nucleic acid carrier

    SciTech Connect

    Dattagupta, N.; Kamarch, M.E.

    1989-04-25

    In passing labeled cells through a cell sorter, the improvement which comprises employing a labeled cell comprising a cell, an antibody specific to and bound to such cell, a nucleic acid fragment joined to the antibody, and a plurality of labels on the nucleic acid fragment. Because of the presence of multiple labels, the sensitivity of the separation of labeled cells in increased.

  5. A rapid method for the evaluation of the ionic permeabilities across epithelial cell membranes.

    PubMed

    Movileanu, L

    1999-02-08

    This short note presents a recipe for the calculation of the ionic permeabilities across epithelial cell membranes. The method requires the Goldman-Hodgkin-Katz formalism as well as the consideration of the equivalent electrical circuit for an epithelial cell. The equivalent electrical circuit is solved in terms of the equivalent electromotive forces coupled in series with the ionic resistances of both cell membranes (apical and basolateral). The present procedure is feasible for any leaky epithelial cell membrane with the condition that this membrane (apical or basolateral) does not contain primary or secondary mechanisms for active transport.

  6. Novel hydrophobic ionic liquids electrolyte based on cyclic sulfonium used in dye-sensitized solar cells

    SciTech Connect

    Guo, Lei; Pan, Xu; Wang, Meng; Zhang, Changneng; Fang, Xiaqin; Chen, Shuanghong; Dai, Songyuan

    2011-01-15

    A novel series of hydrophobic room temperature ionic liquids based on six cyclic sulfonium cations were first time synthesized and applied in dye-sensitized solar cells as pure solvents for electrolyte system. The chronoamperograms result showed that the length of substituent on sulfonium cations could inhibit the I{sub 3}{sup -} diffusion and the five-ring structure of sulfonium was benefit for fast triiodide ion diffusion. The electrochemical impendence spectra measurement of dye-sensitized solar cells with these ionic liquid electrolytes was carried out and the result indicated that the cations' structure had indeed influence on the cells' performance especially for the fill factor, which was further proved by the measurement result of I-V curves of these dye-sensitized solar cells. The conclusion was obtained that the electron exchange reaction on Pt counter electrode/electrolyte interface dominated the cells' performance for these ionic liquid electrolyte-based DSCs. (author)

  7. The determination of ionic transport properties at high pressures in a diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Wang, Qinglin; Liu, Cailong; Han, Yonghao; Gao, Chunxiao; Ma, Yanzhang

    2016-12-01

    A two-electrode configuration was adopted in an in situ impedance measurement system to determine the ionic conductivity at high pressures in a diamond anvil cell. In the experimental measurements, Mo thin-films were specifically coated on tops of the diamond anvils to serve as a pair of capacitance-like electrodes for impedance spectrum measurements. In the spectrum analysis, a Warburg impedance element was introduced into the equivalent circuit to reveal the ionic transport property among other physical properties of a material at high pressures. Using this method, we were able to determine the ionic transport character including the ionic conductivity and the diffusion coefficient of a sodium azide solid to 40 GPa.

  8. Activation of Cell Surface Bound 20S Proteasome Inhibits Vascular Cell Growth and Arteriogenesis

    PubMed Central

    Ito, Wulf D.; Lund, Natalie; Zhang, Ziyang; Buck, Friedrich; Lellek, Heinrich; Horst, Andrea; Machens, Hans-Günther; Schunkert, Heribert; Schaper, Wolfgang; Meinertz, Thomas

    2015-01-01

    Arteriogenesis is an inflammatory process associated with rapid cellular changes involving vascular resident endothelial progenitor cells (VR-EPCs). Extracellular cell surface bound 20S proteasome has been implicated to play an important role in inflammatory processes. In our search for antigens initially regulated during collateral growth mAb CTA 157-2 was generated against membrane fractions of growing collateral vessels. CTA 157-2 stained endothelium of growing collateral vessels and the cell surface of VR-EPCs. CTA 157-2 bound a protein complex (760 kDa) that was identified as 26 kDa α7 and 21 kDa β3 subunit of 20S proteasome in mass spectrometry. Furthermore we demonstrated specific staining of 20S proteasome after immunoprecipitation of VR-EPC membrane extract with CTA 157-2 sepharose beads. Functionally, CTA 157-2 enhanced concentration dependently AMC (7-amino-4-methylcoumarin) cleavage from LLVY (N-Succinyl-Leu-Leu-Val-Tyr) by recombinant 20S proteasome as well as proteasomal activity in VR-EPC extracts. Proliferation of VR-EPCs (BrdU incorporation) was reduced by CTA 157-2. Infusion of the antibody into the collateral circulation reduced number of collateral arteries, collateral proliferation, and collateral conductance in vivo. In conclusion our results indicate that extracellular cell surface bound 20S proteasome influences VR-EPC function in vitro and collateral growth in vivo. PMID:26146628

  9. Ionic Liquids as Quasihydrostatic Pressure Media for Diamond Anvil Cell Experiments

    NASA Astrophysics Data System (ADS)

    Mayorga, Sierra; Moldowan, Kaela; Dan, Ioana; Forster, Paul; Iota, Valentin

    2012-02-01

    Ionic liquids (ILs) are salts in which the ions are poorly coordinated to the point where the eutectic mixture remains liquid at room temperature. In general, ILs exhibit high chemical and thermal stability, have extended liquid regions in the pressure-temperature domain, and can be easily obtained. Commercial ionic liquids are relatively inexpensive and custom ionic solutions can be easily synthesized by mixing common reactants. These properties make ionic liquids attractive candidates for high-pressure media in Diamond Anvil Cell (DAC) experiments. In this presentation we explore the use of ionic liquids as DAS quasihydrostatic pressure media for pressures up to 50 GPa. As a measure of hydrostaticity we monitor the splitting and peak-widths of the R1 andR 2 fluorescence lines from small ruby chips (Al2O3 :Cr^3+) imbedded in the pressure medium. We present results on a series of commercially available ionic fluids against standard pressure media: methanol-ethanol mixtures, silicone oil, sodium chloride (NaCl) and noble gases (Ar, Ne, He).

  10. AFM visualization of cortical filaments/network under cell-bound membrane vesicles.

    PubMed

    Zhang, Xiaojun; Tang, Qisheng; Wu, Li; Huang, Jie; Chen, Yong

    2015-10-01

    While circulating/plasma membrane vesicles have been extensively characterized, due to the lack of effective methods cell-bound membrane vesicles are poorly understood including their shape and correlation with the intracellular cytoskeleton. In this study, we focused on cell-bound membrane vesicles and individual vesicle-derived pits on endothelial cells by using confocal microscopy and atomic force microscopy (AFM). For the first time, we found that cell-bound membrane vesicles are hemisphere-shaped and that the actin cortical filaments/network lies at the cytosolic opening of a vesicle instead of being closely attached to the inner side of the vesicle membrane. This structure of cell-bound membrane vesicles may be beneficial to their movement in, or release from, the plasma membrane of cells due to less membrane-cytoskeleton coupling to be broken therefore probably minimizing energy consumption and time usage. Further study indicates that TNF-α activation induced a significant increase in average number/size of cell-bound vesicles and the local disruption of the actin network at the cytosolic opening of cell-bound vesicles. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Ionic liquids and ionic liquid acids with high temperature stability for fuel cell and other high temperature applications, method of making and cell employing same

    DOEpatents

    Angell, C Austen [Mesa, AZ; Xu, Wu [Broadview Heights, OH; Belieres, Jean-Philippe [Chandler, AZ; Yoshizawa, Masahiro [Tokyo, JP

    2011-01-11

    Disclosed are developments in high temperature fuel cells including ionic liquids with high temperature stability and the storage of inorganic acids as di-anion salts of low volatility. The formation of ionically conducting liquids of this type having conductivities of unprecedented magnitude for non-aqueous systems is described. The stability of the di-anion configuration is shown to play a role in the high performance of the non-corrosive proton-transfer ionic liquids as high temperature fuel cell electrolytes. Performance of simple H.sub.2(g) electrolyte/O.sub.2(g) fuel cells with the new electrolytes is described. Superior performance both at ambient temperature and temperatures up to and above 200.degree. C. are achieved. Both neutral proton transfer salts and the acid salts with HSO.sup.-.sub.4 anions, give good results, the bisulphate case being particularly good at low temperatures and very high temperatures. The performance of all electrolytes is improved by the addition of a small amount of involatile base of pK.sub.a value intermediate between those of the acid and base that make the bulk electrolyte. The preferred case is the imidazole-doped ethylammonium hydrogensulfate which yields behavior superior in all respects to that of the industry standard phosphoric acid electrolyte.

  12. Hydrophobic ionic liquids for quantitative bacterial cell lysis with subsequent DNA quantification.

    PubMed

    Fuchs-Telka, Sabine; Fister, Susanne; Mester, Patrick-Julian; Wagner, Martin; Rossmanith, Peter

    2017-02-01

    DNA is one of the most frequently analyzed molecules in the life sciences. In this article we describe a simple and fast protocol for quantitative DNA isolation from bacteria based on hydrophobic ionic liquid supported cell lysis at elevated temperatures (120-150 °C) for subsequent PCR-based analysis. From a set of five hydrophobic ionic liquids, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide was identified as the most suitable for quantitative cell lysis and DNA extraction because of limited quantitative PCR inhibition by the aqueous eluate as well as no detectable DNA uptake. The newly developed method was able to efficiently lyse Gram-negative bacterial cells, whereas Gram-positive cells were protected by their thick cell wall. The performance of the final protocol resulted in quantitative DNA extraction efficiencies for Gram-negative bacteria similar to those obtained with a commercial kit, whereas the number of handling steps, and especially the time required, was dramatically reduced. Graphical Abstract After careful evaluation of five hydrophobic ionic liquids, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMPyr (+) ][Ntf 2(-) ]) was identified as the most suitable ionic liquid for quantitative cell lysis and DNA extraction. When used for Gram-negative bacteria, the protocol presented is simple and very fast and achieves DNA extraction efficiencies similar to those obtained with a commercial kit. ddH 2 O double-distilled water, qPCR quantitative PCR.

  13. Silicon microhole arrays architecture for stable and efficient photoelectrochemical cells using ionic liquids electrolytes

    NASA Astrophysics Data System (ADS)

    Shen, Xiaojuan; Chen, Ling; Li, Junnan; Zhao, Jie

    2016-06-01

    Silicon microhole arrays (SiMHs) structure is constructed and fabricated by a low-cost maskless anodic etching process, which is applied as the photoanode for the silicon photoelectrochemical (PEC) cells. The depths of silicon microhole arrays can be independently controlled by the etching time. The light-scattering properties are also investigated. Additionally, surface morphology analysis show that large hole diameters of SiMHs is very favourable for the full-filling of ionic liquids electrolyte. Therefore, better electrochemical contact as well as high ionic conductivity of the ionic liquids electrolyte renders the PEC SiMHs solar cells to exhibit more excellent performance. After optimization, the maximum PCE could be achieved at 4.04% for the SiMHs cell. The performance of the SiMHs cell is highly comparable to that of silicon nanowires cell. More importantly, the liquid-state electrolyte is confined in the unique microhole structure, which can obviously prevent the leakage of the ionic liquids electrolyte, resulting in much better long-term stability than the reference devices. These preliminary results validate the concept of interpenetrating networks with semiconductor structure/ILs junction to develop stable and efficient PEC cells.

  14. Transverse high gradient magnetic filter cell with bounded flow field

    SciTech Connect

    Badescu, V.; Rotariu, O.; Murariu, V.; Rezlescu, N.

    1997-11-01

    The capture of fine paramagnetic particles from a fluid suspension in a magnetic filter element of a novel design is analyzed. Unlike the systems previously analyzed, in the model the flow is bounded by two by two parallel planar plates, and the ferromagnetic wires are installed outside these spaces, within planes parallel with the plates. The analysis is based on the study of particle trajectories, considering the laminar flow of carrier fluid. From these the authors establish the conditions for the maximum recovery of the particles in suspension. This study is useful in designing magnetic filter batteries with corrosion-protected ferromagnetic wires.

  15. Hysteresis phenomena in perovskite solar cells: the many and varied effects of ionic accumulation.

    PubMed

    Jacobs, Daniel A; Wu, Yiliang; Shen, Heping; Barugkin, Chog; Beck, Fiona J; White, Thomas P; Weber, Klaus; Catchpole, Kylie R

    2017-01-25

    The issue of hysteresis in perovskite solar cells has now been convincingly linked to the presence of mobile ions within the perovskite layer. Here we test the limits of the ionic theory by attempting to account for a number of exotic characterization results using a detailed numerical device model that incorporates ionic charge accumulation at the perovskite interfaces. Our experimental observations include a temporary enhancement in open-circuit voltage following prolonged periods of negative bias, dramatically S-shaped current-voltage sweeps, decreased current extraction following positive biasing or "inverted hysteresis", and non-monotonic transient behaviours in the dark and the light. Each one of these phenomena can be reproduced and ultimately explained by our models, providing further evidence for the ionic theory of hysteresis as well as valuable physical insight into the factors that coincide to bring these phenomena about. In particular we find that both interfacial recombination and carrier injection from the selective contacts are heavily affected by ionic accumulation, and are essential to explaining the non-monotonic voltage transients and S-shaped J-V curves. Inverted hysteresis is attributed to the occurrence of "positive" ionic accumulation, which may also be responsible for enhancing the stabilized open-circuit voltage in some perovskite cells.

  16. Effects of surface morphology on the ionic capacitance and performance of perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Hong; Liang, Chun-Jun; Zhang, Hui-Min; Sun, Meng-Jie; Liang, Jing-Jing; Zhang, Xue-Wen; Ji, Chao; Guo, Ze-Bang; Xu, Ya-Jun; He, Zhi-Qun

    2017-09-01

    The accumulated ionic interface charge (IIC) affects the performance of perovskite solar cells significantly. In this study, we establish a model to describe the formation of capacitance. Mobile ions in perovskite accumulate at the interface and form a plate capacitor with screen charge on the electrodes. Reducing the roughness of perovskite or covering with a thick electron transporting layer significantly regulates the ionic capacitance. The results indicate that mobile ions exist in the perovskite layer, the accumulated IIC density is determined by the thickness of the carrier transport layer, and the capacitor area is affected by interface roughness.

  17. Proton Conducting Polymer Membrane Using The Ionic Liquid 2-Hydroxyethylammonium Lactate For Ethanol Fuel Cells

    NASA Astrophysics Data System (ADS)

    Oliveira, L.; José, N. M.; Boaventura, J.; Iglesias, M.; Mattedi, S.

    2011-12-01

    In this work, there were developed a proton conducting polymer membrane using an ammonium based protic ionic liquid: 2-hydroxyethylamominum lactate for use in proton exchange fuel cells (PEMFC). This kind of ionic liquid has been proven to be biodegradable and they have potentially low toxicity besides low cost of preparation, simple synthesis and purification. The prepared membranes are hybrid organic-inorganic materials. The polymeric matrix is prepared with polydimethylsiloxane (PDMS) mixed with tetraethoxysilane (TEOS) in a ratio of 70/30% in weight. Then, the eletrolytical mixture containing sodium monododecylsulfate (SDS) and the ionic liquid was introduced in the lattice near the gel point, there were used different proportions of the eletrolyte from 5 to 30% in weight. The prepared membranes were characterized using infrared spectroscopy (FTIR), X-ray diffraction (DRX), termogravimetric analysis (TGA), scanning electronic microscopy (SEM) and conductivity and impedance measurements. The prepared materials are flexible, with good thermal and mechanical stability and with a great potential to be used as conducting membranes of fuel cells. The used mixture minimizes the lixiviation lost of the ionic liquid from the polymeric membrane and enhances the cell efficiency if compared with traditional synthetic membranes.

  18. Myocardial cell membrane stress ionic dyskinesia reversal by diltiazem

    PubMed Central

    Gomes, OM; Gomes, ES

    2006-01-01

    Based on previous observations of cardioplegic ionic myocardial distress, myocardial stress dyskinesia was investigated as another possible cause of exercise stress testing-induced silent myocardial ischemia by analyzing the efficacy of the myocytic calcium channel blocker diltiazem in normalizing the results of patients who previously tested positive. From October 2004 to February 2006, 25 patients (13 women [52%]; aged between 28 and 71 years; mean age 56.9 years) complaining of precordial pain, with no coronary artery obstruction detected by scintigraphy and coronary cineangiography studies, presenting with positive ergometric testing, defined by ST segment depression, with no precordial pain or arrhythmia during testing, were treated with diltiazem in three daily doses of 90 mg, and were restudied five or seven days after the first examination. Treadmill electrocardiography exercise testing was performed using the standard Bruce protocol, analyzing the following parameters: the J point and Y point of the ST segment depression, maximum oxygen uptake reached, heart rate, double product and exercise performance measured in metabolic equivalents. The administration of diltiazem abolished patients’ complaints of atypical precordial pain in all cases and blocked ST segment depression, both J point (control: mean 2.3±0.5 mm; with treatment: 0.4±0.5 mm; P<0.001) and Y point (control: mean 1.9±0.7 mm; with treatment: 0.1±0.3 mm; P<0.001). The heart rate variations were not significant (P>0.05), with mean values of 156.2±12.0 beats/min for the control and 149.0±19.2 beats/min with treatment. There was significant (P<0.01) improvement in the functional classification of the heart with treatment (mean 2.7±0.9 for the control and 2.0±0.7 with treatment), without significant variations (P>0.05) in maximum oxygen uptake and double product results. The administration of the myocytic calcium channel blocker diltiazem impeded the occurrence of the silent ST segment

  19. Non-Ionic Highly Permeable Polymer Shells for Encapsulation of Living Cells

    DTIC Science & Technology

    2011-05-01

    Rights License 14. ABSTRACT We introduce novel, truly non-ionic hydrogen -bonded layer-by-layer (LbL) coatings for cell surface engineering capable of...Encapsulation 1 Methods of Cell Encapsulation 2 Electrostatic vs. Hydrogen -bonded Shell Performance 10 2 Goals & Objectives 13 3 Methods 14 Layer by...PEI(TA/PVPON)4 hollow shells dried on a silicon wafer 12 Figure 10: Schematic illustrating LbL assembly of hydrogen bonded layers 14

  20. Activation of beta-glucan synthases by wall-bound purple acid phosphatase in tobacco cells.

    PubMed

    Kaida, Rumi; Satoh, Yumi; Bulone, Vincent; Yamada, Yohko; Kaku, Tomomi; Hayashi, Takahisa; Kaneko, Takako S

    2009-08-01

    Wall-bound purple acid phosphatases have been shown to be potentially involved in the regulation of plant cell growth. The aim of this work was to further investigate the function of one of these phosphatases in tobacco (Nicotiana tabacum), NtPAP12, using transgenic cells overexpressing the enzyme. The transgenic cells exhibited a higher level of phosphatase activity in their walls. The corresponding protoplasts regenerating a cell wall exhibited a higher rate of beta-glucan synthesis and cellulose deposition was increased in the walls of the transgenic cells. A higher level of plasma membrane glucan synthase activities was also measured in detergent extracts of membrane fractions from the transgenic line, while no activation of Golgi-bound glycan synthases was detected. Enzymatic hydrolysis and methylation analysis were performed on the products synthesized in vitro by the plasma membrane enzymes from the wild-type and transgenic lines extracted with digitonin and incubated with radioactive UDP-glucose. The data showed that the glucans consisted of callose and cellulose and that the amount of each glucan synthesized by the enzyme preparation from the transgenic cells was significantly higher than in the case of the wild-type cells. The demonstration that callose and cellulose synthases are activated in cells overexpressing the wall-bound phosphatase NtPAP12 suggests a regulation of these carbohydrate synthases by a phosphorylation/dephosphorylation process, as well as a role of wall-bound phosphatases in the regulation of cell wall biosynthesis.

  1. Cell-bound lipase and esterase of Brevibacterium linens.

    PubMed

    Sorhaug, T; Ordal, Z J

    1974-03-01

    The activities of glycerol ester hydrolase, lipase (EC 3.1.1.3) and carboxylesterase, and esterase (EC 3.1.1.1) were determined for whole cell preparations of Brevibacterium linens by using the pH-stat assay. The culture growth liquors were inactive against the three substrates, tributyrin emulsion, triacetin, and methyl butyrate. Cells washed in water had less activity than cells washed in 5% NaCl; the ratio of activities was close to 1:2 for all strains using tributyrin emulsion as the substrate. For the esterase substrates, this relationship varied widely and was strain dependent. The ability to hydrolyze the two esterase substrates varied independently of the level of lipase activity.

  2. Toxicity of substrate-bound amyloid peptides on vascular smooth muscle cells is enhanced by homocysteine.

    PubMed

    Mok, Su San; Turner, Bradley J; Beyreuther, Konrad; Masters, Colin L; Barrow, Colin J; Small, David H

    2002-06-01

    Tauhe main component of cerebral amyloid angiopathy (CAA) in Alzheimer's disease is the amyloid-beta protein (Abeta), a 4-kDa polypeptide derived from the beta-amyloid protein precursor (APP). The accumulation of Abeta in the basement membrane has been implicated in the degeneration of adjacent vascular smooth muscle cells (VSMC). However, the mechanism of Abeta toxicity is still unclear. In this study, we examined the effect of substrate-bound Abeta on VSMC in culture. The use of substrate-bound proteins in cell culture mimics presentation of the proteins to cells as if bound to the basement membrane. Substrate-bound Abeta peptides were found to be toxic to the cells and to increase the rate of cell death. This toxicity was dependent on the length of time the peptide was allowed to 'age', a process by which Abeta is induced to aggregate over several hours to days. Oxidative stress via hydrogen peroxide (H2O2) release was not involved in the toxic effect, as no decrease in toxicity was observed in the presence of catalase. However, substrate-bound Abeta significantly reduced cell adhesion compared to cells grown on plastic alone, indicating that cell-substrate adhesion may be important in maintaining cell viability. Abeta also caused an increase in the number of apoptotic cells. This increase in apoptosis was accompanied by activation of caspase-3. Homocysteine, a known risk factor for cerebrovascular disease, increased Abeta-induced toxicity and caspase-3 activation in a dose-dependent manner. These studies suggest that Abeta may activate apoptotic pathways to cause loss of VSMC in CAA by inhibiting cell-substrate interactions. Our studies also suggest that homocysteine, a known risk factor for other cardiovascular diseases, could also be a risk factor for hemorrhagic stroke associated with CAA.

  3. Radioprotection of Human Cell Nuclear DNA by Polyamines: Radiosensitivity of Chromatin is Influenced by Tightly Bound Spermine

    NASA Technical Reports Server (NTRS)

    Warters, Raymond L.; Newton, Gerald L.; Olive, Peggy L.; Fahey, Robert C.

    1999-01-01

    The polyamines putrescine (PUT) and spermine (SPM) were examined for their ability to protect human cell Deoxyribonucleic Acid (DNA) against the formation of radiation-induced double-strand breaks (DSBs). As observed previously, under conditions where polyamines were shown to be almost completely absent, association with nuclear matrix protein into a nucleoid, and organization into chromatin structure, protected DNA from induction of DSBs by factors of 4.5 and 95, respectively. At concentrations below 1 mM, PUT or SPM provided equivalent levels of protection to deproteinized nuclear DNA, consistent with their capacity to scavenge radiation-induced radicals. At constant ionic strength, 5 mM SPM protected deproteinized DNA and nucleoid DNA and DNA in nuclear chromatin by factors of 100 and 26, respectively. At 5 mM, SPM provided 15 times greater protection of deproteinized DNA than did PUT. Under physiologically relevant conditions, 5 mM SPM protected DNA in the intact nucleus from the induction of DSBs by a factor of 2 relative to DNA in the absence of SPM. Studies of SPM binding during cellular fractionation revealed that a significant fraction of the cellular SPM is tightly bound in the nucleus but can be removed by extended washing. Thus the association of SPM with nuclear chromatin appears to be a significant contributor to the resistance of the cell's DNA to the induction of DSBs.

  4. Radioprotection of Human Cell Nuclear DNA by Polyamines: Radiosensitivity of Chromatin is Influenced by Tightly Bound Spermine

    NASA Technical Reports Server (NTRS)

    Warters, Raymond L.; Newton, Gerald L.; Olive, Peggy L.; Fahey, Robert C.

    1999-01-01

    The polyamines putrescine (PUT) and spermine (SPM) were examined for their ability to protect human cell Deoxyribonucleic Acid (DNA) against the formation of radiation-induced double-strand breaks (DSBs). As observed previously, under conditions where polyamines were shown to be almost completely absent, association with nuclear matrix protein into a nucleoid, and organization into chromatin structure, protected DNA from induction of DSBs by factors of 4.5 and 95, respectively. At concentrations below 1 mM, PUT or SPM provided equivalent levels of protection to deproteinized nuclear DNA, consistent with their capacity to scavenge radiation-induced radicals. At constant ionic strength, 5 mM SPM protected deproteinized DNA and nucleoid DNA and DNA in nuclear chromatin by factors of 100 and 26, respectively. At 5 mM, SPM provided 15 times greater protection of deproteinized DNA than did PUT. Under physiologically relevant conditions, 5 mM SPM protected DNA in the intact nucleus from the induction of DSBs by a factor of 2 relative to DNA in the absence of SPM. Studies of SPM binding during cellular fractionation revealed that a significant fraction of the cellular SPM is tightly bound in the nucleus but can be removed by extended washing. Thus the association of SPM with nuclear chromatin appears to be a significant contributor to the resistance of the cell's DNA to the induction of DSBs.

  5. First line treatment of advanced non-small-cell lung cancer – specific focus on albumin bound paclitaxel

    PubMed Central

    Gupta, Neha; Hatoum, Hassan; Dy, Grace K

    2014-01-01

    Lung cancer is the leading cause of cancer mortality worldwide in both men and women. Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for more than 80% of cases. Paclitaxel has a broad spectrum of activity against various malignancies, including NSCLC. Paclitaxel is poorly soluble in water and thus, until recently, its commercially available preparations contained a non-ionic solvent Cremophor EL®. Cremophor EL® improves the solubility of paclitaxel and allows its intravenous administration. However, certain side-effects associated with paclitaxel, such as hypersensitivity reactions, myelosuppression, and peripheral neuropathy, are known to be worsened by Cremophor®. Nanoparticle albumin-bound paclitaxel ([nab-paclitaxel] ABRAXANE® ABI-007) is a new generation formulation of paclitaxel that obviates the need for Cremophor®, resulting in a safer and faster infusion without requiring the use of premedications to avoid hypersensitivity. Albumin-binding receptor-mediated delivery and lack of sequestering Cremophor® micelles allow higher intratumoral concentration of pharmacologically active paclitaxel. Multiple clinical trials have demonstrated a superior tolerability profile of nab-paclitaxel in comparison to solvent-bound paclitaxel (sb-paclitaxel). A recent Phase III trial compared the effects of weekly nab-paclitaxel in combination with carboplatin versus sb-paclitaxel in combination with carboplatin given every 3 weeks for first line treatment of NSCLC. This trial highlights the weekly nab-paclitaxel combination as an alternate treatment option for NSCLC, with higher response rate in squamous cell NSCLC and longer survival in elderly patients. This review will focus on the properties of nab-paclitaxel and its use in the first line treatment of NSCLC. PMID:24399877

  6. First line treatment of advanced non-small-cell lung cancer - specific focus on albumin bound paclitaxel.

    PubMed

    Gupta, Neha; Hatoum, Hassan; Dy, Grace K

    2014-01-01

    Lung cancer is the leading cause of cancer mortality worldwide in both men and women. Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for more than 80% of cases. Paclitaxel has a broad spectrum of activity against various malignancies, including NSCLC. Paclitaxel is poorly soluble in water and thus, until recently, its commercially available preparations contained a non-ionic solvent Cremophor EL®. Cremophor EL® improves the solubility of paclitaxel and allows its intravenous administration. However, certain side-effects associated with paclitaxel, such as hypersensitivity reactions, myelosuppression, and peripheral neuropathy, are known to be worsened by Cremophor®. Nanoparticle albumin-bound paclitaxel ([nab-paclitaxel] ABRAXANE® ABI-007) is a new generation formulation of paclitaxel that obviates the need for Cremophor®, resulting in a safer and faster infusion without requiring the use of premedications to avoid hypersensitivity. Albumin-binding receptor-mediated delivery and lack of sequestering Cremophor® micelles allow higher intratumoral concentration of pharmacologically active paclitaxel. Multiple clinical trials have demonstrated a superior tolerability profile of nab-paclitaxel in comparison to solvent-bound paclitaxel (sb-paclitaxel). A recent Phase III trial compared the effects of weekly nab-paclitaxel in combination with carboplatin versus sb-paclitaxel in combination with carboplatin given every 3 weeks for first line treatment of NSCLC. This trial highlights the weekly nab-paclitaxel combination as an alternate treatment option for NSCLC, with higher response rate in squamous cell NSCLC and longer survival in elderly patients. This review will focus on the properties of nab-paclitaxel and its use in the first line treatment of NSCLC.

  7. The prion protein family member Shadoo induces spontaneous ionic currents in cultured cells

    PubMed Central

    Nyeste, Antal; Stincardini, Claudia; Bencsura, Petra; Cerovic, Milica; Biasini, Emiliano; Welker, Ervin

    2016-01-01

    Some mutant forms of the cellular prion protein (PrPC) carrying artificial deletions or point mutations associated with familial human prion diseases are capable of inducing spontaneous ionic currents across the cell membrane, conferring hypersensitivity to certain antibiotics to a wide range of cultured cells and primary cerebellar granular neurons (CGNs). These effects are abrogated when the wild type (WT) form is co-expressed, suggesting that they might be related to a physiological activity of PrPC. Interestingly, the prion protein family member Shadoo (Sho) makes cells hypersensitive to the same antibiotics as mutant PrP-s, an effect that is diminished by the co-expression of WT-PrP. Here, we report that Sho engages in another mutant PrP-like activity: it spontaneously induces large ionic currents in cultured SH-SY5Y cells, as detected by whole-cell patch clamping. These currents are also decreased by the co-expression of WT-PrP. Furthermore, deletion of the N-terminal (RXXX)8 motif of Sho, mutation of the eight arginine residues of this motif to glutamines, or replacement of the hydrophobic domain by that of PrP, also diminish Sho-induced ionic currents. Our results suggest that the channel activity that is also characteristic to some pathogenic PrP mutants may be linked to a physiological function of Sho. PMID:27819308

  8. Characterization of ionic currents of circular smooth muscle cells of the canine pyloric sphincter.

    PubMed

    Vogalis, F; Sanders, K M

    1991-05-01

    1. The ionic currents of circular muscle cells from canine pyloric sphincter were characterized using the whole-cell patch clamp technique. 2. Subpopulations of circular muscle cells from the myenteric and submucosal halves of the circular layer were isolated and studied separately to determine whether differences in the currents expressed by these cells could explain differences in electrical behaviour observed in situ. 3. Resting potentials of isolated cells were about 20 mV positive to cells in intact muscles. Polarization under current clamp to the level of tissue resting potentials caused spontaneous discharge of action potentials in many cells. 4. Outward current measured under voltage clamp could be divided into a voltage-dependent component and a voltage- and Ca(2+)-dependent component. The latter was affected by manipulations of external [Ca2+], nifedipine and dialysis of cells with EGTA. 5. A few cells exhibited a channel that was activated with hyperpolarization. These channels produced inward current at potentials positive to the potassium reversal potential, EK, and reversed at -13 mV. 6. Inward currents, recorded from Cs(+)-loaded cells, were characterized by a transient phase and a sustained phase that persisted throughout the test depolarization. The inward current was reduced by nifedipine but in some cells a nifedipine-resistant component was observed. 7. There were no fundamental differences in the ionic currents recorded from circular muscle cells from the myenteric and submucosal regions, suggesting that the electrical activity of the tissue must be dependent upon structural characteristics (i.e. electrical coupling, fibre bundle dimensions, etc.) of the tissue. 8. The ionic conductance characterized can be related to many of the excitable events recorded from pyloric muscles.

  9. Functions of dendritic-cell-bound IgE in allergy

    PubMed Central

    Platzer, Barbara; Stout, Madeleine; Fiebiger, Edda

    2015-01-01

    Immunoglobulin E (IgE) functions as an Fc-receptor-bound antigen sensor for mast cells and basophils, the classical effector cells of allergy. A cell-bound IgE pool is formed when monomeric IgE binds to FcεRI, the high affinity IgE Fc receptor on these cells, and minor amounts of antigen are sufficient to trigger the pro-allergic innate IgE effector axis. Additionally, FcεRI is constitutively expressed on human dendritic cells (DCs), and thus the latter cell type also receives signals via cell-bound IgE. Notably, steady-state expression of FcεRI on DCs is absent in SPF-housed mice. How DCs integrate IgE/FcεRI-derived signals into their sentinel functions as gatekeepers of immunity was therefore only recently studied with transgenic mice that phenocopy human FcεRI expression. In this review, we summarize advances in our understanding of the functions of DC-bound IgE which demonstrate that IgE-mediated activation of DCs in allergic Th2-type inflammation appears to be immune regulatory rather than pro-inflammatory. PMID:26052071

  10. Functions of dendritic-cell-bound IgE in allergy.

    PubMed

    Platzer, Barbara; Stout, Madeleine; Fiebiger, Edda

    2015-12-01

    Immunoglobulin E (IgE) functions as an Fc-receptor-bound antigen sensor for mast cells and basophils, the classical effector cells of allergy. A cell-bound IgE pool is formed when monomeric IgE binds to FcɛRI, the high affinity IgE Fc receptor on these cells, and minor amounts of antigen are sufficient to trigger the pro-allergic innate IgE effector axis. Additionally, FcɛRI is constitutively expressed on human dendritic cells (DCs), and thus the latter cell type also receives signals via cell-bound IgE. Notably, steady-state expression of FcɛRI on DCs is absent in SPF-housed mice. How DCs integrate IgE/FcɛRI-derived signals into their sentinel functions as gatekeepers of immunity was therefore only recently studied with transgenic mice that phenocopy human FcɛRI expression. In this review, we summarize advances in our understanding of the functions of DC-bound IgE which demonstrate that IgE-mediated activation of DCs in allergic Th2-type inflammation appears to be immune regulatory rather than pro-inflammatory. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Comparative in vitro study of cholinium-based ionic liquids and deep eutectic solvents toward fish cell line.

    PubMed

    Radošević, Kristina; Železnjak, Jelena; Cvjetko Bubalo, Marina; Radojčić Redovniković, Ivana; Slivac, Igor; Gaurina Srček, Višnja

    2016-09-01

    With the advent of ionic liquids, much was expected concerning their applicability as an alternative to organic solvents in the chemical technology and biotechnology fields. However, the most studied and commonly used ionic liquids based on imidazolium and pyridinium were found not to be as environmentally friendly as it was first expected. Therefore, a new generation of alternative solvents named natural ionic liquids and deep eutectic solvents, composed of natural and/or renewable compounds, have come into focus in recent years. Since the number of newly synthesized chemicals increases yearly, simple and reliable methods for their ecotoxicological assessment are necessary. Permanent fish cell lines can serve as a test system for the evaluation of a chemical's cytotoxicity. This paper presents research results on the cytotoxic effects on Channel Catfish Ovary (CCO) cell line induced by fifteen cholinium-based ionic liquids and deep eutectic solvents. Based on the decrease in cell viability, the most obvious toxic effect on CCO cells was caused by ionic liquid choline oxalate, while other solvents tested exhibited low cytotoxicity. Therefore, we can conclude that cholinium-based ionic liquids and deep eutectic solvents are comparatively less toxic to CCO cells than conventional ionic liquids.

  12. Investigation of dermal toxicity of ionic liquids in monolayer-cultured skin cells and 3D reconstructed human skin models.

    PubMed

    Hwang, Jee-Hyun; Park, Hyeonji; Choi, Dal Woong; Nam, Ki Taek; Lim, Kyung-Min

    2017-09-25

    Ionic liquids have gained increasing attention in the chemical industry as potential green substitutes for traditional solvents. However, little is known about toxicity of ionic liquids on the skin, a major exposure portal to toxic substances. Here, we evaluated dermal toxicity of ionic liquids using human keratinocyte and fibroblast cell line, 3D reconstructed human epidermis, and full-thickness model to investigate underlying mechanisms. Cytotoxicity of ionic liquids was evaluated for representative anions, [TFSI], [PF6], [BF4], and [DCA], as well as for cations, [EMIM], [BMPY], [TBA] and [Zn], in human keratinocyte cell line, HaCaT, and human dermal fibroblasts. In our results, significant cytotoxicity was induced by ionic liquids with [TFSI] in both cell lines. Notably, cytotoxicity of [TFSI] containing ionic liquids was comparable to xylene, a toxic conventional organic solvent. Fluorescent and flow cytometric analysis revealed that [TFSI]-exposed cells underwent necrotic cell death. Reactive oxygen species (ROS) was increased while the amount of glutathione was decreased by [TFSI] in dose-dependent manner, which was reversed by antioxidant, N-acetylcysteine. In 3D reconstructed human epidermis and full-thickness model, a single application of [TFSI] induced toxicity although it was minimal and largely limited to epidermal layer. Collectively, these results demonstrated potential dermal toxicity of ionic liquids. Copyright © 2017. Published by Elsevier Ltd.

  13. Malignant H1299 tumour cells preferentially internalize iron-bound inositol hexakisphosphate.

    PubMed

    Helmis, Christina; Blechner, Christine; Lin, Hongying; Schweizer, Michaela; Mayr, Georg W; Nielsen, Peter; Windhorst, Sabine

    2013-10-22

    In colon enterocytes and in well-differentiated colon cancer CaCo-2 cells, InsP6 (inositol hexakisphosphate) inhibits iron uptake by forming extracellular insoluble iron/InsP6 complexes. In this study, we confirmed that CaCo-2 cells are not able to take up iron/InsP6 but, interestingly, found that the cells are able to internalize metal-free and Cr3+-bound InsP6. Thus, the inability of CaCo-2 cells to take up iron/InsP6 complexes seems to be due to the iron-bound state of InsP6. Since recently we demonstrated that the highly malignant bronchial carcinoma H1299 cells internalize and process InsP6, we examined whether these cells may be able to take up iron/InsP6 complexes. Indeed, we found that InsP6 dose-dependently increased uptake of iron and demonstrated that in the iron-bound state InsP6 is more effectively internalized than in the metal-free or Cr3+-bound state, indicating that H1299 cells preferentially take up iron/InsP6 complexes. Electron microscope and cell fraction assays indicate that after uptake H1299 cells mainly stored InsP6/iron in lysosomes as large aggregates, of which about 10% have been released to the cytosol. However, this InsP6-mediated iron transport had no significant effects on cell viability. This result together with our finding that the well-differentiated CaCo-2 cells did not, but the malignant H1299 cells preferentially took up iron/InsP6, may offer the possibility to selectively transport cytotoxic substances into tumour cells.

  14. Perfluoro anion based binary and ternary ionic liquids as electrolytes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lin, Hsi-Hsin; Peng, Jia-De; Suryanarayanan, V.; Velayutham, D.; Ho, Kuo-Chuan

    2016-04-01

    In this work, eight new ionic liquids (ILs) based on triethylammonium (TEA) or n-methylpiperidinium (NMP) cations and perfluoro carboxylate (PFC) anions having different carbon chain lengths are synthesized and their physico-chemical properties such as density, decomposition temperature, viscosity and conductivity are determined. Photovoltaic characteristics of dye-sensitized solar cells (DSSCs) with binary ionic liquids electrolytes, containing the mixture of the synthesized ILs and 1-methyl-3-propyl imidazolium iodide (PMII) (v/v = 35/65), are evaluated. Among the different ILs, solar cells containing NMP based ILs show higher VOC than that of TEA, whereas, higher JSC is noted for the DSSCs incorporated with the latter when compared to the former. Further, the photo-current of the DSSCs decreases with the increase of the carbon chain length of perfluoro carboxylate anionic group of ILs. The cell performance of the DSSC containing ternary ionic liquids-based electrolytes compose of NMP-2C/TEA-2C/PMII (v/v/v = 28/7/65) exhibits a JSC of 12.99 mA cm-2, a VOC of 639.0 mV, a FF of 0.72, and a cell efficiency of 6.01%. The extraordinary durability of the DSSC containing the above combination of electrolytes stored in dark at 50 °C is proved to be unfailing up to 1200 h.

  15. Environmentally Friendly Recycling of Fuel-Cell Membrane Electrode Assemblies by Using Ionic Liquids.

    PubMed

    Balva, Maxime; Legeai, Sophie; Leclerc, Nathalie; Billy, Emmanuel; Meux, Eric

    2017-07-21

    The platinum nanoparticles used as the catalyst in proton exchange membrane fuel cells (PEMFCs) represent approximately 46 % of the total price of the cells for a large-scale production, and this is one of the barriers to their commercialization. Therefore, the recycling of the platinum catalyst could be the best alternative to limit the production costs of PEMFCs. The usual recovery routes for spent catalysts containing platinum are pyro-hydrometallurgical processes in which a calcination step is followed by aqua regia treatment, and these processes generate fumes and NOx emissions, respectively. The electrochemical recovery route proposed here is more environmentally friendly, performed under "soft" temperature conditions, and does not result in any gas emissions. It consists of the coupling of the electrochemical leaching of platinum in chloride-based ionic liquids (ILs), followed by its electrodeposition. The leaching of platinum was studied in pure ILs and in ionic-liquid melts at different temperatures and with different chloride contents. Through the modulation of the composition of the ionic-liquid melts, it is possible to leach and electrodeposit the platinum from fuel-cell electrodes in a single-cell process under an inert or ambient atmosphere. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Ionic Liquid Electrolytes for Flexible Dye-Sensitized Solar Cells

    DTIC Science & Technology

    2014-09-01

    High-Efficiency Solar - Cell Based on Dye-Sensitized Colloidal TiO2 Films,” a DSSC consists of four main components: a photoanode, a counter... solar cell modules. 2. Experiment and Calculations 2.1 Materials Commercial TiO2 paste was purchased from Dyesol, and additional nanophase TiO2 ...B.; Grätzel, M. A Low-Cost, High Efficiency Solar Cell Based on Dye_Sensitized Colloidal TiO2 Films. Nature 1991, 353, 737–740. 2. Snaith, H. J

  17. Falsification of the ionic channel theory of hair cell transduction.

    PubMed

    Rossetto, Michelangelo

    2013-11-01

    The hair cell provides the transduction of mechanical vibrations in the balance and acoustic sense of all vertebrates that swim, walk, or fly. The current theory places hair cell transduction in a mechanically controlled ion channel. Although the theory of a mechanical input modulating the flow of ions through an ion pore has been a useful tool, it is falsified by experimental data in the literature and can be definitively falsified by a proposed experiment.

  18. Modification of the activity of cell wall-bound peroxidase by hypergravity in relation to the stimulation of lignin formation in azuki bean epicotyls

    NASA Astrophysics Data System (ADS)

    Wakabayashi, Kazuyuki; Nakano, Saho; Soga, Kouichi; Hoson, Takayuki

    Lignin is a component of cell walls of terrestrial plants, which provides cell walls with the mechanical rigidity. Lignin is a phenolic polymer with high molecular mass and formed by the polymerization of phenolic substances on a cellulosic matrix. The polymerization is catalyzed by cell wall-bound peroxidase, and thus the activity of this enzyme regulates the rate of formation of lignin. In the present study, the changes in the lignin content and the activity of cell wall peroxidase were investigated along epicotyls of azuki bean seedlings grown under hypergravity conditions. The endogenous growth occurred primarily in the upper regions of the epicotyl and no growth was detected in the middle or basal regions. The amounts of acetyl bromide-soluble lignin increased from the upper to the basal regions of epicotyls. The lignin content per unit length in the basal region was three times higher than that in the upper region. Hypergravity treatment at 300 g for 6 h stimulated the increase in the lignin content in all regions of epicotyls, particularly in the basal regions. The peroxidase activity in the protein fraction extracted from the cell wall preparation with a high ionic strength buffer also increased gradually toward the basal region, and hypergravity treatment clearly increased the activity in all regions. There was a close correlation between the lignin content and the enzyme activity. These results suggest that gravity stimuli modulate the activity of cell wall-bound peroxidase, which, in turn, causes the stimulation of the lignin formation in stem organs.

  19. Comment on "Modeling of electrode polarization for electrolytic cells with a limited ionic adsorption"

    NASA Astrophysics Data System (ADS)

    Alexe-Ionescu, A. L.; Barbero, G.; Lelidis, I.

    2014-05-01

    Recently, Sawada [Phys. Rev. E 88, 032406 (2013), 10.1103/PhysRevE.88.032406] proposed a model to take into account the dielectric dispersion of ionic origin in a weak electrolyte cell. We first show that the model is based on questionable assumptions. Next, we point out an error in the author's calculation of the current in the external circuit. Finally, we demonstrate why some criticism on recent papers is irrelevant.

  20. Targeting anticancer drug delivery to pancreatic cancer cells using a fucose-bound nanoparticle approach.

    PubMed

    Yoshida, Makoto; Takimoto, Rishu; Murase, Kazuyuki; Sato, Yasushi; Hirakawa, Masahiro; Tamura, Fumito; Sato, Tsutomu; Iyama, Satoshi; Osuga, Takahiro; Miyanishi, Koji; Takada, Kohichi; Hayashi, Tsuyoshi; Kobune, Masayoshi; Kato, Junji

    2012-01-01

    Owing to its aggressiveness and the lack of effective therapies, pancreatic ductal adenocarcinoma has a dismal prognosis. New strategies to improve treatment and survival are therefore urgently required. Numerous fucosylated antigens in sera serve as tumor markers for cancer detection and evaluation of treatment efficacy. Increased expression of fucosyltransferases has also been reported for pancreatic cancer. These enzymes accelerate malignant transformation through fucosylation of sialylated precursors, suggesting a crucial requirement for fucose by pancreatic cancer cells. With this in mind, we developed fucose-bound nanoparticles as vehicles for delivery of anticancer drugs specifically to cancer cells. L-fucose-bound liposomes containing Cy5.5 or Cisplatin were effectively delivered into CA19-9 expressing pancreatic cancer cells. Excess L-fucose decreased the efficiency of Cy5.5 introduction by L-fucose-bound liposomes, suggesting L-fucose-receptor-mediated delivery. Intravenously injected L-fucose-bound liposomes carrying Cisplatin were successfully delivered to pancreatic cancer cells, mediating efficient tumor growth inhibition as well as prolonging survival in mouse xenograft models. This modality represents a new strategy for pancreatic cancer cell-targeting therapy.

  1. Role of low density lipoprotein-bound cholesterol esters in acute lymphoblastic leukemia cells

    SciTech Connect

    Cutts, J.L.; Madden, E.A.; Melnykovych, G.

    1986-05-01

    The glucocorticoid sensitive CEM-C7 T-cell line was derived from human acute lymphoblastic leukemia cells by Norman and Thompson. Madden et al. have demonstrated that this growth inhibitory effect is due in part to a glucocorticoid-mediated inhibition of cholesterol synthesis and can be partially reversed by cholesterol dispersions. To further delineate the role of cholesterol in this growth inhibition, they have examined the ability of low density lipoprotein (LDL)-bound (/sup 3/H)cholesterol linoleate to reverse the growth inhibitory effect of 1 ..mu..M dexamethasone (Dex) on the CEM-C7 cells. LDL-bound cholesterol linoleate was unable to reverse the Dex-mediated growth inhibition, although incorporation of (/sup 14/C) acetate into free cholesterol was inhibited by 29%, following the Brown and Goldstein model. The presence of Dex further inhibited acetate incorporation into free cholesterol in the LDL-treated cells. Under all conditions, more than 99% of the acetate incorporated into cholesterol was present as free cholesterol, while over 87% of the LDL-bound cholesterol linoleate taken up remained in the ester compartment. These results indicate that CEM-C7 cells are unable to utilize LDL-bound cholesterol esters as a source of free cholesterol and rely on endogenous synthesis for their free cholesterol requirements.

  2. Proteomic responses of human intestinal Caco-2 cells exposed to silver nanoparticles and ionic silver.

    PubMed

    Oberemm, Axel; Hansen, Ulf; Böhmert, Linda; Meckert, Christine; Braeuning, Albert; Thünemann, Andreas F; Lampen, Alfonso

    2016-03-01

    Even although quite a number of studies have been performed so far to demonstrate nanoparticle-specific effects of substances in living systems, clear evidence of these effects is still under debate. The present study was designed as a comparative proteomic analysis of human intestinal cells exposed to a commercial silver nanoparticle reference material and ions from AgNO3. A two-dimensional gel electrophoresis/MALDI mass spectrometry (MS)-based proteomic analysis was conducted after 24-h incubation of differentiated Caco-2 cells with non-cytotoxic and low cytotoxic silver concentrations (2.5 and 25 µg ml(-1) nanosilver, 0.5 and 5 µg ml(-1) AgNO3). Out of an overall number of 316 protein spots differentially expressed at a fold change of ≥ 1.4 or ≤ -1.4 in all treatments, 169 proteins could be identified. In total, 231 spots were specifically deregulated in particle-treated groups compared with 41 spots, which were limited to AgNO3-treatments. Forty-four spots (14 %) were commonly deregulated by both types of treatment. A considerable fraction of the proteins differentially expressed after treatment with nanoparticles is related to protein folding, synthesis or modification of proteins as well as cellular assembly and organization. Overlays of networks obtained for particulate and ionic treatments showed matches, indicating common mechanisms of combined particle and ionic silver exposure and exclusive ionic silver treatment. However, proteomic responses of Caco-2 cells treated with higher concentrations of silver species also showed some differences, for example regarding proteins related to fatty acid and energy metabolism, suggesting an induction of also some different molecular mechanisms for particle exposure and ionic treatment.

  3. In vitro cytotoxicity assessment of imidazolium ionic liquids: biological effects in fish Channel Catfish Ovary (CCO) cell line.

    PubMed

    Radošević, Kristina; Cvjetko, Marina; Kopjar, Nevenka; Novak, Rudjer; Dumić, Jerka; Srček, Višnja Gaurina

    2013-06-01

    Increasing interest in the application of ionic liquids as green replacement for volatile organic solvents emphasized the need for the evaluation of their toxic effects at different biological systems in order to reduce the risk for human health and environment. To our knowledge, effects of imidazolium ionic liquids on cellular level of fish cell lines have not been studied yet. The cytotoxicity of imidazolium ionic liquids containing different anions and alkyl chain lengths as the substituent at the cation ring towards the fish CCO cell line was determined by WST-1 proliferation assay. Morphological alterations were examined by fluorescent microscopy using acridine orange/ethidium bromide staining and flow cytometry analysis was also performed. The results showed concentration-dependent cytotoxicity of ionic liquids in CCO cells, related to the type of anion and alkyl chain length, while EC50 values showed moderate to high cytotoxicity of tested imidazolium ionic liquids. Distinct morphological changes observed under fluorescence microscope and data obtained by flow cytometry suggest that the toxicity of imidazolium ionic liquids with longer alkyl chains could be related to necrosis. Results presented in here may be helpful for filling existing gaps of knowledge about ionic liquids toxicity and their impact on aquatic environment.

  4. AN IMPROVED CELL FRACTIONATION PROCEDURE FOR THE PREPARATION OF RAT LIVER MEMBRANE-BOUND RIBOSOMES

    PubMed Central

    Adelman, M. R.; Blobel, Gunter; Sabatini, David D.

    1973-01-01

    A cell fractionation procedure is described which allows the preparation from rat liver of a rough microsome population containing almost 50% of the membrane-bound ribosomes of the tissue. The fraction is not contaminated with free ribosomes or smooth microsomes, and, by various other criteria, is suitable for studies of ribosome-membrane interaction. PMID:4345164

  5. Probable systemic lupus erythematosus with cell-bound complement activation products (CB-CAPS).

    PubMed

    Lamichhane, D; Weinstein, A

    2016-08-01

    Complement activation is a key feature of systemic lupus erythematosus (SLE). Detection of cell-bound complement activation products (CB-CAPS) occurs more frequently than serum hypocomplementemia in definite lupus. We describe a patient with normocomplementemic probable SLE who did not fulfill ACR classification criteria for lupus, but the diagnosis was supported by the presence of CB-CAPS.

  6. Cell-bound exopolysaccharides of Lactobacillus brevis KB290: protective role and monosaccharide composition.

    PubMed

    Suzuki, Shigenori; Yakabe, Takafumi; Suganuma, Hiroyuki; Fukao, Masanori; Saito, Tadao; Yajima, Nobuhiro

    2013-08-01

    We examined the survivability of Lactobacillus brevis KB290 and derivative strain KB392 in artificial digestive juices and bile salts. The strains have similar membrane fatty acids but different amounts of cell-bound exopolysaccharides (EPS). In artificial digestive juices, KB290 showed significantly higher survivability than KB392, and homogenization, which reduced the amount of EPS in KB290 but not in KB392, reduced the survivability only of KB290. In bile salts, KB290 showed significantly higher survivability than KB392, and cell-bound EPS extraction with EDTA reduced the survivability of only KB290. Transmission electron microscopy showed there to be a greater concentration of cell-bound EPS in KB290 than in either KB392 or EDTA-treated or homogenized KB290. We conclude that KB290's cell-bound EPS (which high performance liquid chromatography showed to be made up of glucose and N-acetylglucosamine) played an important role in bile salt tolerance.

  7. Ionic immune suppression within the tumour microenvironment limits T cell effector function

    PubMed Central

    Eil, Robert; Vodnala, Suman K; Clever, David; Klebanoff, Christopher A; Sukumar, Madhusudhanan; Pan, Jenny H; Palmer, Douglas C; Gros, Alena; Yamamoto, Tori N; Patel, Shashank J; Guittard, Geoffrey C; Yu, Zhiya; Carbonaro, Valentina; Okkenhaug, Klaus; Schrump, David S; Linehan, W Marston; Roychoudhuri, Rahul; Restifo, Nicholas P

    2016-01-01

    Tumours progress despite being infiltrated by tumour-specific effector T cells1. Tumours contain areas of cellular necrosis, which is associated with poor survival in a variety of cancers2. Here, we show that necrosis releases an intracellular ion, potassium, into the extracellular fluid of mouse and human tumours causing profound suppression of T cell effector function. We find that elevations in the extracellular potassium concentration [K+]e act to impair T cell receptor (TCR)-driven Akt-mTOR phosphorylation and effector programmes, this potassium-mediated suppression of Akt-mTOR signalling and T cell function is dependent upon the activity of the serine/threonine phosphatase PP2A3,4. While the suppressive effect mediated by elevated [K+]e is independent of changes in plasma membrane potential (Vm), it does require an increase in intracellular potassium ([K+]i). Concordantly, ionic reprogramming of tumour-specific T cells through overexpression of the potassium channel Kv1.3 lowers [K+]i and improves effector functions in vitro and in vivo. Consequently, Kv1.3 T cell overexpression enhances tumour clearance and survival of melanoma-bearing mice. These results uncover a previously undescribed ionic checkpoint blocking T cell function within tumours and identify new strategies for cancer immunotherapy. PMID:27626381

  8. Highly Efficient Plastic Crystal Ionic Conductors for Solid-state Dye-sensitized Solar Cells

    PubMed Central

    Hwang, Daesub; Kim, Dong Young; Jo, Seong Mu; Armel, Vanessa; MacFarlane, Douglas R.; Kim, Dongho; Jang, Sung-Yeon

    2013-01-01

    We have developed highly efficient, ambient temperature, solid-state ionic conductors (SSICs) for dye-sensitized solar cells (DSSCs) by doping a molecular plastic crystal, succinonitrile (SN), with trialkyl-substituted imidazolium iodide salts. High performance SSICs with enhanced ionic conductivity (2–4 mScm−1) were obtained. High performance solid-state DSSCs with power conversion efficiency of 7.8% were fabricated using our SSICs combined with unique hierarchically nanostructured TiO2 sphere (TiO2-SP) photoelectrodes; these electrodes have significant macroporosity, which assists penetration of the solid electrolyte into the electrode. The performance of our solid-state DSSCs is, to the best of our knowledge, the highest reported thus far for cells using plastic crystal-based SSICs, and is comparable to that of the state-of-the-art DSSCs which use ionic liquid type electrolytes. This report provides a logical strategy for the development of efficient plastic crystal-based SSICs for DSSCs and other electrochemical devices. PMID:24343425

  9. Ionic liquid electrolyte based on S-propyltetrahydrothiophenium iodide for dye-sensitized solar cells

    SciTech Connect

    Guo, Lei; Pan, Xu; Zhang, Changneng; Liu, Weiqing; Wang, Meng; Fang, Xiaqin; Dai, Songyuan

    2010-03-15

    A new ionic liquid S-propyltetrahydrothiophenium iodide (T{sub 3}I) was developed as the solvent and iodide ion source in electrolyte for dye-sensitized solar cells. The electrochemical behavior of the I{sub 3}{sup -}/I{sup -} redox couple and effect of additives in this ionic liquid system was tested and the results showed that this ionic liquid electrolyte revealed good conducting abilities and potential application for solar devices. The effects of LiI and dark-current inhibitors were investigated. The dye-sensitized solar cell with the electrolyte (0.1 mol L{sup -1} LiI, 0.35 mol L{sup -1} I{sub 2}, 0.5 mol L{sup -1} NMBI in pure T{sub 3}I) gave short-circuit photocurrent density (J{sub sc}) of 11.22 mA cm{sup 2}, open-circuit voltage (V{sub oc}) of 0.61 V and fill factor (FF) of 0.51, corresponding to the photoelectric conversion efficiency ({eta}) of 3.51% under one Sun (AM1.5). (author)

  10. Finite state projection based bounds to compare chemical master equation models using single-cell data.

    PubMed

    Fox, Zachary; Neuert, Gregor; Munsky, Brian

    2016-08-21

    Emerging techniques now allow for precise quantification of distributions of biological molecules in single cells. These rapidly advancing experimental methods have created a need for more rigorous and efficient modeling tools. Here, we derive new bounds on the likelihood that observations of single-cell, single-molecule responses come from a discrete stochastic model, posed in the form of the chemical master equation. These strict upper and lower bounds are based on a finite state projection approach, and they converge monotonically to the exact likelihood value. These bounds allow one to discriminate rigorously between models and with a minimum level of computational effort. In practice, these bounds can be incorporated into stochastic model identification and parameter inference routines, which improve the accuracy and efficiency of endeavors to analyze and predict single-cell behavior. We demonstrate the applicability of our approach using simulated data for three example models as well as for experimental measurements of a time-varying stochastic transcriptional response in yeast.

  11. Finite state projection based bounds to compare chemical master equation models using single-cell data

    NASA Astrophysics Data System (ADS)

    Fox, Zachary; Neuert, Gregor; Munsky, Brian

    2016-08-01

    Emerging techniques now allow for precise quantification of distributions of biological molecules in single cells. These rapidly advancing experimental methods have created a need for more rigorous and efficient modeling tools. Here, we derive new bounds on the likelihood that observations of single-cell, single-molecule responses come from a discrete stochastic model, posed in the form of the chemical master equation. These strict upper and lower bounds are based on a finite state projection approach, and they converge monotonically to the exact likelihood value. These bounds allow one to discriminate rigorously between models and with a minimum level of computational effort. In practice, these bounds can be incorporated into stochastic model identification and parameter inference routines, which improve the accuracy and efficiency of endeavors to analyze and predict single-cell behavior. We demonstrate the applicability of our approach using simulated data for three example models as well as for experimental measurements of a time-varying stochastic transcriptional response in yeast.

  12. Genetic and Biochemical Studies on Cell-Bound α-Amylase in Bacillus subtilis Marburg

    PubMed Central

    Nagata, Yoshiho; Yamaguchi, Kazuo; Maruo, Bunji

    1974-01-01

    A small but significant amount of α-amylase activity was detected in the cells of Bacillus subtilis Marburg. The cell-associated activity was almost constant regardless of the level of extracellular α-amylase activity. The cell-bound amylase activity could be separated into three components, upon Sephadex G-75 chromatography, referred to as components A, B, and C. Component C showed the same properties as the extracellular α-amylases so far examined. Component A had a molecular weight greater than 70,000, as judged from the elution position on Sephadex G-75, and became smaller upon treatment with trypsin but was still larger than that of component C. An α-amylase mutant that lacked extracellular α-amylase completely because of a mutation within the structural gene of the enzyme was found to lose all three cell-bound amylase components simultaneously. These data suggest strongly that the cell-bound amylase components are precursors of the extracellular α-amylase and that the α-amylase of this organism is produced under the direction of the same gene whether the enzyme is within or outside the cell. PMID:4212029

  13. Acoustophoretic microfluidic chip for sequential elution of surface bound molecules from beads or cells

    PubMed Central

    Augustsson, Per; Malm, Johan; Ekström, Simon

    2012-01-01

    An acoustophoresis-based microfluidic flow-chip is presented as a novel platform to facilitate analysis of proteins and peptides loosely bound to the surface of beads or cells. The chip allows for direct removal of the background surrounding the beads or cells, followed by sequential treatment and collection of a sequence of up to five different buffer conditions. During this treatment, the beads/cells are retained in a single flow by acoustic radiation force. Eluted peptides are collected from the outlets and subsequently purified by miniaturized solid-phase extraction and analyzed with matrix assisted laser desorption mass spectrometry. Fundamental parameters such as the system fluidics and dispersion are presented. The device was successfully applied for wash and sequential elution of peptides bound to the surface of microbeads and human spermatozoa, respectively. PMID:24003343

  14. A global sensitivity tool for cardiac cell modeling: Application to ionic current balance and hypertrophic signaling.

    PubMed

    Sher, Anna A; Cooling, Michael T; Bethwaite, Blair; Tan, Jefferson; Peachey, Tom; Enticott, Colin; Garic, Slavisa; Gavaghan, David J; Noble, Denis; Abramson, David; Crampin, Edmund J

    2010-01-01

    Cardiovascular diseases are the major cause of death in the developed countries. Identifying key cellular processes involved in generation of the electrical signal and in regulation of signal transduction pathways is essential for unraveling the underlying mechanisms of heart rhythm behavior. Computational cardiac models provide important insights into cardiovascular function and disease. Sensitivity analysis presents a key tool for exploring the large parameter space of such models, in order to determine the key factors determining and controlling the underlying physiological processes. We developed a new global sensitivity analysis tool which implements the Morris method, a global sensitivity screening algorithm, onto a Nimrod platform, which is a distributed resources software toolkit. The newly developed tool has been validated using the model of IP3-calcineurin signal transduction pathway model which has 30 parameters. The key driving factors of the IP3 transient behaviour have been calculated and confirmed to agree with previously published data. We next demonstrated the use of this method as an assessment tool for characterizing the structure of cardiac ionic models. In three latest human ventricular myocyte models, we examined the contribution of transmembrane currents to the shape of the electrical signal (i.e. on the action potential duration). The resulting profiles of the ionic current balance demonstrated the highly nonlinear nature of cardiac ionic models and identified key players in different models. Such profiling suggests new avenues for development of methodologies to predict drug action effects in cardiac cells.

  15. The ionic bases of the action potential in isolated mouse cardiac Purkinje cell.

    PubMed

    Vaidyanathan, Ravi; O'Connell, Ryan P; Deo, Makarand; Milstein, Michelle L; Furspan, Philip; Herron, Todd J; Pandit, Sandeep V; Musa, Hassan; Berenfeld, Omer; Jalife, José; Anumonwo, Justus M B

    2013-01-01

    Collecting electrophysiological and molecular data from the murine conduction system presents technical challenges. Thus, only little advantage has been taken of numerous genetically engineered murine models to study excitation through the cardiac conduction system of the mouse. To develop an approach for isolating murine cardiac Purkinje cells (PCs), to characterize major ionic currents and to use the data to simulate action potentials (APs) recorded from PCs. Light microscopy was used to isolate and identify PCs from apical and septal cells. Current and voltage clamp techniques were used to record APs and whole cell currents. We then simulated a PC AP on the basis of our experimental data. APs recorded from PCs were significantly longer than those recorded from ventricular cells. The prominent plateau phase of the PC AP was very negative (≈-40 mV). Spontaneous activity was observed only in PCs. The inward rectifier current demonstrated no significant differences compared to ventricular myocytes (VMs). However, sodium current density was larger, and the voltage-gated potassium current density was significantly less in PCs compared with myocytes. T-type Ca(2+) currents (I(Ca,T)) were present in PCs but not VMs. Computer simulations suggest that I(Ca,T) and cytosolic calcium diffusion significantly modulate AP profile recorded in PCs, as compared to VMs. Our study provides the first comprehensive ionic profile of murine PCs. The data show unique features of PC ionic mechanisms that govern its excitation process. Experimental data and numerical modeling results suggest that a smaller voltage-gated potassium current and the presence of I(Ca,T) are important determinants of the longer and relatively negative plateau phase of the APs. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  16. Identification of HLA-DR–bound peptides presented by human bronchoalveolar lavage cells in sarcoidosis

    PubMed Central

    Wahlström, Jan; Dengjel, Jörn; Persson, Bengt; Duyar, Hüseyin; Rammensee, Hans-Georg; Stevanoviδc, Stefan; Eklund, Anders; Weissert, Robert; Grunewald, Johan

    2007-01-01

    Sarcoidosis is an inflammatory disease of unknown etiology, most commonly affecting the lungs. Activated CD4+ T cells accumulate in the lungs of individuals with sarcoidosis and are considered to be of central importance for inflammation. We have previously shown that Scandinavian sarcoidosis patients expressing the HLA-DR allele DRB1*0301 are characterized by large accumulations in the lungs of CD4+ T cells expressing the TCR AV2S3 gene segment. This association afforded us a unique opportunity to identify a sarcoidosis-specific antigen recognized by AV2S3+ T cells. To identify candidates for the postulated sarcoidosis-specific antigen, lung cells from 16 HLA-DRB1*0301pos patients were obtained by bronchoalveolar lavage. HLA-DR molecules were affinity purified and bound peptides acid eluted. Subsequently, peptides were separated by reversed-phase HPLC and analyzed by liquid chromatography–mass spectrometry. We identified 78 amino acid sequences from self proteins presented in the lungs of sarcoidosis patients, some of which were well-known autoantigens such as vimentin and ATP synthase. For the first time, to our knowledge, we have identified HLA-bound peptides presented in vivo during an inflammatory condition. This approach can be extended to characterize HLA-bound peptides in various autoimmune settings. PMID:17975675

  17. Characterization of antibody binding to cell surface antigens using a plasma membrane-bound plate assay.

    PubMed

    Vater, C A; Reid, K; Bartle, L M; Goldmacher, V S

    1995-01-01

    A procedure has been developed for measuring antibody binding to cell surface antigens using an immobilized plasma membrane fraction. In this method, isolated plasma membranes are dried onto wells of a 96-well microtiter plate and incubated with antibodies that recognize a cell surface protein. Bound antibody is detected indirectly using an enzyme-linked or fluorescently tagged second antibody. Alternatively, the primary antibody itself can be labeled and its binding can be detected directly. The assay is simple and fast and provides several advantages over whole cell binding assays currently in widespread use.

  18. Acidic Ionic Liquids.

    PubMed

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition.

  19. Modifying dielectrophoretic response of nonviable yeast cells by ionic surfactant treatment.

    PubMed

    Tang, Shi-Yang; Zhang, Wei; Baratchi, Sara; Nasabi, Mahyar; Kalantar-Zadeh, Kourosh; Khoshmanesh, Khashayar

    2013-07-02

    Nonviable cells are essential biosystems, due to the functionalities they offer and their effects on viable cells. Therefore, the separation and immobilization of nonviable cells separately or in the vicinity of viable cells is of great importance for many fundamentals investigations in cell biology. However, most nonviable cells become less polarizable than the surrounding medium at conductivities above 0.01 S/m. This means that in such a medium, dielectrophoresis, despite its great versatilities for manipulation of cells, cannot be employed for immobilizing nonviable cells. Here, we present a novel approach to change the dielectrophoretic (DEP) response of nonviable yeast cells by treating them with low concentrations of ionic surfactants such as sodium dodecyl sulfate. After this treatment, they exhibit a strong positive DEP response, even at high medium conductivities. The capability of this treatment is demonstrated in two proof-of-concept experiments. First, we show the sorting and immobilization of viable and nonviable yeast cells, along consecutive microelectrode arrays. Second, we demonstrate the immobilization of viable and nonviable cells in the vicinity of each other along the same microelectrode array. The proposed technique allows DEP platforms to be utilized for the immobilization and subsequent postanalysis of both viable and nonviable cells with and without the presence of each other.

  20. A gradient of matrix-bound FGF-2 and perlecan is available to lens epithelial cells.

    PubMed

    Wu, Weiju; Tholozan, Frederique M; Goldberg, Martin W; Bowen, Leon; Wu, Junjie; Quinlan, Roy A

    2014-03-01

    Fibroblast growth factors play a key role in regulating lens epithelial cell proliferation and differentiation via an anteroposterior gradient that exists between the aqueous and vitreous humours. FGF-2 is the most important for lens epithelial cell proliferation and differentiation. It has been proposed that the presentation of FGF-2 to the lens epithelial cells involves the lens capsule as a source of matrix-bound FGF-2. Here we used immunogold labelling to measure the matrix-bound FGF-2 gradient on the inner surface of the lens capsule in flat-mounted preparations to visualize the FGF-2 available to lens epithelial cells. We also correlated FGF-2 levels with levels of its matrix-binding partner perlecan, a heparan sulphate proteoglycan (HSPG) and found the levels of both to be highest at the lens equator. These also coincided with increased levels of phosphorylated extracellular signal-regulated kinase 1 and 2 (pERK1/2) in lens epithelial cells that localised to condensed chromosomes of epithelial cells that were Ki-67 positive. The gradient of matrix-bound FGF-2 (anterior pole: 3.7 ± 1.3 particles/μm2; equator: 8.2 ± 1.9 particles/μm2; posterior pole: 4 ± 0.9 particles/μm2) and perlecan (anterior pole: 2.1 ± 0.4 particles/μm2; equator: 5 ± 2 particles/μm2; posterior pole: 1.9 ± 0.7 particles/μm2) available at the inner lens capsule surface was measured for the bovine lens. These data support the anteroposterior gradient hypothesis and provide the first measurement of the gradient for an important morphogen and its HSPG partner, perlecan, at the epithelial cell-lens capsule interface.

  1. How a T Cell Receptor-like Antibody Recognizes Major Histocompatibility Complex-bound Peptide

    SciTech Connect

    Mareeva, T.; Martinez-Hackert, E; Sykulev, Y

    2008-01-01

    We determined the crystal structures of the T cell receptor (TCR)-like antibody 25-D1.16 Fab fragment bound to a complex of SIINFEKL peptide from ovalbumin and the H-2Kb molecule. Remarkably, this antibody directly 'reads' the structure of the major histocompatibility complex (MHC)-bound peptide, employing the canonical diagonal binding mode utilized by most TCRs. This is in marked contrast with another TCR-like antibody, Hyb3, bound to melanoma peptide MAGE-A1 in association with HLA-A1 MHC class I. Hyb3 assumes a non-canonical orientation over its cognate peptide-MHC and appears to recognize a conformational epitope in which the MHC contribution is dominant. We conclude that TCR-like antibodies can recognize MHC-bound peptide via two different mechanisms: one is similar to that exploited by the preponderance of TCRs and the other requires a non-canonical antibody orientation over the peptide-MHC complex.

  2. Proteomic Analysis to Identify Tightly-Bound Cell Wall Protein in Rice Calli.

    PubMed

    Cho, Won Kyong; Hyun, Tae Kyung; Kumar, Dhinesh; Rim, Yeonggil; Chen, Xiong Yan; Jo, Yeonhwa; Kim, Suwha; Lee, Keun Woo; Park, Zee-Yong; Lucas, William J; Kim, Jae-Yean

    2015-08-01

    Rice is a model plant widely used for basic and applied research programs. Plant cell wall proteins play key roles in a broad range of biological processes. However, presently, knowledge on the rice cell wall proteome is rudimentary in nature. In the present study, the tightly-bound cell wall proteome of rice callus cultured cells using sequential extraction protocols was developed using mass spectrometry and bioinformatics methods, leading to the identification of 1568 candidate proteins. Based on bioinformatics analyses, 389 classical rice cell wall proteins, possessing a signal peptide, and 334 putative non-classical cell wall proteins, lacking a signal peptide, were identified. By combining previously established rice cell wall protein databases with current data for the classical rice cell wall proteins, a comprehensive rice cell wall proteome, comprised of 496 proteins, was constructed. A comparative analysis of the rice and Arabidopsis cell wall proteomes revealed a high level of homology, suggesting a predominant conservation between monocot and eudicot cell wall proteins. This study importantly increased information on cell wall proteins, which serves for future functional analyses of these identified rice cell wall proteins.

  3. Proteomic Analysis to Identify Tightly-Bound Cell Wall Protein in Rice Calli

    PubMed Central

    Cho, Won Kyong; Hyun, Tae Kyung; Kumar, Dhinesh; Rim, Yeonggil; Chen, Xiong Yan; Jo, Yeonhwa; Kim, Suwha; Lee, Keun Woo; Park, Zee-Yong; Lucas, William J.; Kim, Jae-Yean

    2015-01-01

    Rice is a model plant widely used for basic and applied research programs. Plant cell wall proteins play key roles in a broad range of biological processes. However, presently, knowledge on the rice cell wall proteome is rudimentary in nature. In the present study, the tightly-bound cell wall proteome of rice callus cultured cells using sequential extraction protocols was developed using mass spectrometry and bioinformatics methods, leading to the identification of 1568 candidate proteins. Based on bioinformatics analyses, 389 classical rice cell wall proteins, possessing a signal peptide, and 334 putative non-classical cell wall proteins, lacking a signal peptide, were identified. By combining previously established rice cell wall protein databases with current data for the classical rice cell wall proteins, a comprehensive rice cell wall proteome, comprised of 496 proteins, was constructed. A comparative analysis of the rice and Arabidopsis cell wall proteomes revealed a high level of homology, suggesting a predominant conservation between monocot and eudicot cell wall proteins. This study importantly increased information on cell wall proteins, which serves for future functional analyses of these identified rice cell wall proteins. PMID:26194822

  4. Three-dimensional ionic conduction in the strained electrolytes of solid oxide fuel cells

    SciTech Connect

    Han, Yupei; Zou, Minda; Lv, Weiqiang; He, Weidong; Mao, Yiwu; Wang, Wei

    2016-05-07

    Flexible power sources including fuel cells and batteries are the key to realizing flexible electronic devices with pronounced foldability. To understand the bending effects in these devices, theoretical analysis on three-dimensional (3-D) lattice bending is necessary. In this report, we derive a 3-D analytical model to analyze the effects of electrolyte crystal bending on ionic conductivity in flexible solid-state batteries/fuel cells. By employing solid oxide fuel cells as a materials' platform, the intrinsic parameters of bent electrolyte materials, including lattice constant, Young's modulus, and Poisson ratio, are evaluated. Our work facilitates the rational design of highly efficient flexible electrolytes for high-performance flexible device applications.

  5. Three-dimensional ionic conduction in the strained electrolytes of solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Han, Yupei; Zou, Minda; Lv, Weiqiang; Mao, Yiwu; Wang, Wei; He, Weidong

    2016-05-01

    Flexible power sources including fuel cells and batteries are the key to realizing flexible electronic devices with pronounced foldability. To understand the bending effects in these devices, theoretical analysis on three-dimensional (3-D) lattice bending is necessary. In this report, we derive a 3-D analytical model to analyze the effects of electrolyte crystal bending on ionic conductivity in flexible solid-state batteries/fuel cells. By employing solid oxide fuel cells as a materials' platform, the intrinsic parameters of bent electrolyte materials, including lattice constant, Young's modulus, and Poisson ratio, are evaluated. Our work facilitates the rational design of highly efficient flexible electrolytes for high-performance flexible device applications.

  6. Ionic-liquid-based proton conducting membranes for anhydrous H2/Cl2 fuel-cell applications.

    PubMed

    Liu, Sa; Zhou, Li; Wang, Pengjie; Zhang, Fangfang; Yu, Shuchun; Shao, Zhigang; Yi, Baolian

    2014-03-12

    An ionic-liquid-doped poly(benzimidazole) (PBI) proton-conducting membrane for an anhydrous H2/Cl2 fuel cell has been proposed. Compared with other ionic liquids, such as imidazole-type ionic liquids, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) showed better electrode reaction kinetics (H2 oxidation and Cl2 reduction reaction at platinum) and was more suitable for a H2/Cl2 fuel cell. PBI polymer and [dema][TfO] were compatible with each other, and the hybrid membranes exhibited high stability and good ionic conductivity, reaching 20.73 mS cm(-1) at 160 °C. We also analyzed the proton-transfer mechanism in this ionic-liquid-based membrane and considered that both proton-hopping and diffusion mechanisms existed. In addition, this composite electrolyte worked well in a H2/Cl2 fuel cell under non-water conditions. This work would give a good path to study the novel membranes for anhydrous H2/Cl2 fuel-cell application.

  7. Responses of cultured neural retinal cells to substratum-bound laminin and other extracellular matrix molecules.

    PubMed

    Adler, R; Jerdan, J; Hewitt, A T

    1985-11-01

    The responses of cultured chick embryo retinal neurons to several extracellular matrix molecules are described. Retinal cell suspensions in serum-free medium containing the "N1" supplement (J. E. Bottenstein, S. D. Skaper, S. Varon, and J. Sato, 1980, Exp. Cell Res. 125, 183-190) were seeded on tissue culture plastic surfaces pretreated with polyornithine (PORN) and with one of the factors to be tested. Substantial cell survival could be observed after 72 hr in vitro on PORN pretreated with serum or laminin, whereas most cells appeared to be degenerating on untreated PORN, PORN-fibronectin, and PORN-chondronectin. Cell attachment, although quantitatively similar for all these substrata, was temperature-dependent on serum and laminin but not on fibronectin or untreated PORN. In a short-term bioassay, neurite development was abundant on laminin, scarce on serum and fibronectin, and absent on PORN. No positive correlation between cell spreading and neurite production could be seen: cell spreading was more extensive on PORN and fibronectin than on laminin or serum, while on laminin-treated dishes, spreading was similar for neurite-bearing and non-neurite-bearing cells. Laminin effects on retinal neurons were clearly substratum dependent. When bound to tissue culture plastic, laminin showed a dose-dependent inhibitory effect on cell attachment and did not stimulate neurite development. PORN-bound laminin, on the other hand, did not affect cell attachment but caused marked stimulation of neurite development, suggesting that laminin conformation and/or the spatial distribution of active sites play an important role in the neurite-promoting function of this extracellular matrix molecule. Investigation of the embryonic retina with ELISA and immunocytochemical methods showed that laminin is present in this organ during development. Therefore, in vivo and in vitro observations are consistent with the possibility that laminin might influence neuronal development in the retina.

  8. A hemicellulose-bound form of silicon inhibits cadmium ion uptake in rice (Oryza sativa) cells.

    PubMed

    Ma, Jie; Cai, Hongmei; He, Congwu; Zhang, Wenjun; Wang, Lijun

    2015-05-01

    Silicon (Si) alleviates cadmium (Cd) toxicity in rice (Oryza sativa). However, the chemical mechanisms at the single-cell level are poorly understood. Here, a suspension of rice cells exposed to Cd and/or Si treatments was investigated using a combination of plant cell nutritional, molecular biological, and physical techniques including in situ noninvasive microtest technology (NMT), polymerase chain reaction (PCR), inductively coupled plasma mass spectroscopy (ICP-MS), and atomic force microscopy (AFM) in Kelvin probe mode (KPFM). We found that Si-accumulating cells had a significantly reduced net Cd(2+) influx, compared with that in Si-limited cells. PCR analyses of the expression levels of Cd and Si transporters in rice cells showed that, when the Si concentration in the medium was increased, expression of the Si transporter gene Low silicon rice 1 (Lsi1) was up-regulated, whereas expression of the gene encoding the transporter involved in the transport of Cd, Natural resistance-associated macrophage protein 5 (Nramp5), was down-regulated. ICP-MS results revealed that 64% of the total Si in the cell walls was bound to hemicellulose constituents following the fractionation of the cell walls, and consequently inhibited Cd uptake. Furthermore, AFM in KPFM demonstrated that the heterogeneity of the wall surface potential was higher in cells cultured in the presence of Si than in those cultured in its absence, and was homogenized after the addition of Cd. These results suggest that a hemicellulose-bound form of Si with net negative charges is responsible for inhibition of Cd uptake in rice cells by a mechanism of [Si-hemicellulose matrix]Cd complexation and subsequent co-deposition. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  9. The influence of plasma membrane electrostatic properties on the stability of cell ionic composition.

    PubMed Central

    Genet, S; Costalat, R; Burger, J

    2001-01-01

    An electro-osmotic model is developed to examine the influence of plasma membrane superficial charges on the regulation of cell ionic composition. Assuming membrane osmotic equilibrium, the ion distribution predicted by Gouy-Chapman-Grahame (GCG) theory is introduced into ion transport equations, which include a kinetic model of the Na/K-ATPase based on the stimulation of this ion pump by internal Na(+) ions. The algebro-differential equation system describing dynamics of the cell model has a unique resting state, stable with respect to finite-sized perturbations of various types. Negative charges on the membrane are found to greatly enhance relaxation toward steady state following these perturbations. We show that this heightened stability stems from electrostatic interactions at the inner membrane side that shift resting state coordinates along the sigmoidal activation curve of the sodium pump, thereby increasing the pump sensitivity to internal Na(+) fluctuations. The accuracy of electrostatic potential description with GCG theory is proved using an alternate formalism, based on irreversible thermodynamics, which shows that pressure contribution to ion potential energy is negligible in electrostatic double layers formed at the surfaces of biological membranes. We discuss implications of the results regarding a reliable operation of ionic process coupled to the transmembrane electrochemical gradient of Na(+) ions. PMID:11606261

  10. A polybenzimidazole/ionic-liquid-graphite-oxide composite membrane for high temperature polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Xu, Chenxi; Liu, Xiaoteng; Cheng, Jigui; Scott, Keith

    2015-01-01

    Graphite oxide is successfully functionalised by 3-aminopropyltriethoxysilane ionic liquid and used as a filler material in a polybenzimidazole (PBI) membrane for high temperature proton exchange membrane fuel cells. The ionic-liquid-graphite-oxide/polybenzimidazole (ILGO/PBI) composite membrane exhibits an appropriate level of proton conductivity when imbibed with phosphoric acid at low phosphoric acid loading, which promotes its use in fuel cells by avoiding acid leakage and materials corrosion. The ionic conductivities of the ILGO/PBI membranes at 175 °C are 0.035 S cm-1 and 0.025 S cm-1 at per repeat units of 3.5 and 2.0, respectively. The fuel cell performance of ILGO/PBI membranes exhibits a maximum power density of 320 mW cm-2 at 175 °C, which is higher than that of a pristine PBI membrane.

  11. Peptide specific expansion of CD8(+) T cells by recombinant plate bound MHC/peptide complexes.

    PubMed

    Schmidt, Esben G W; Buus, Søren; Thorn, Mette; Stryhn, Anette; Leisner, Christian; Claesson, Mogens H

    2009-01-01

    Development of methods for efficient in vitro stimulation and expansion of peptide specific CD8(+) T cells is compelling not only with respect to adoptive T cell therapy but also regarding analysis of T cell responses and search for new immunogenic peptides. In the present study, a new approach to in vitro T cell stimulation was investigated. By use of an antigenic peptide derived from the cytomegalovirus (CMVp) we tested the stimulatory efficacy of recombinant plate bound MHC molecules (PB-MHC), being immobilized in culture plates. A single stimulation of non-adherent peripheral blood mononuclear cells (NA-PBMCs) with PB-MHC/CMVp resulted in significant expansion of CMVp specific CD8(+) T cells, which was comparable to that achieved by CMVp pulsed mature dendritic cells (DCs). By repeated exposure of NA-PBMCs to PB-MHC/CMVp more than 60% CMVp specific CD8(+) T cells, representing a 240-fold expansion, were reached after only two stimulations. Although stimulation with PB-MHC/CMVp clearly demonstrated efficient peptide specific expansion of CD8(+) T cells, there was a tendency to proliferative exhaustion of the cells after 3-4 stimulations. Thus, it will be of interest to examine the effect of new stimulatory cocktails, e.g. cytokines and co-stimulatory molecules, by use of the present rapid and easy-to-use method of expanding peptide specific T cells.

  12. Ionic currents activated via purinergic receptors in the cumulus cell-enclosed mouse oocyte.

    PubMed

    Arellano, Rogelio O; Martínez-Torres, Ataulfo; Garay, Edith

    2002-09-01

    Several chemical signals synthesized in the ovary, including neurotransmitters, have been proposed to serve as regulators of folliculogenesis, however, their mechanisms of action have not been completely elucidated. Here, electrophysiological and molecular biology techniques were used to study responses generated via purinergic stimulation in cultured mouse cumulus cell-enclosed oocytes (CEOs). Application of extracellular ATP elicited depolarizing responses in CEOs. Using the voltage clamp technique by impaling oocytes with two microelectrodes, we determined that these responses were mainly due to activation of two distinct ionic currents. The first corresponded to the opening of Ca2+-dependent Cl- channels (I(Cl(Ca))) and the second to the opening of Ca2+-independent channels that are permeable to Na+ (I(c+)). The potency order for different nucleotides (50 micro M) was UTP > ATP > 2meS-ATP > ADP, and alpha,betame-ATP and adenosine were found to be inactive. Suramin (100 micro M) blocked the response elicited by ATP or UTP. In addition, voltage dependent K+ currents activated by depolarization of CEOs were characterized. All CEO ionic currents recorded from the oocyte were completely inhibited by octanol (1 mM), a gap junction blocker. Thus, purinergic responses and K+ currents originate mainly in the membrane of cumulus cells. Transcripts of the purinergic receptor P2Y2 subtype were amplified by polymerase chain reaction from the cDNA of granulosa cells or cumulus cells. This study shows that P2Y2 receptors are expressed in CEOs, and that their stimulation opens at least two different types of ion channels. Both the ion channels and the receptors seemed to be located in the cumulus cells, which transmit their corresponding electrical signals to the oocyte via gap junction channels.

  13. Ionic currents and electromotility in inner ear hair cells from humans.

    PubMed

    Oghalai, J S; Holt, J R; Nakagawa, T; Jung, T M; Coker, N J; Jenkins, H A; Eatock, R A; Brownell, W E

    1998-04-01

    The upright posture and rich vocalizations of primates place demands on their senses of balance and hearing that differ from those of other animals. There is a wealth of behavioral, psychophysical, and CNS measures characterizing these senses in primates, but no prior recordings from their inner ear sensory receptor cells. We harvested human hair cells from patients undergoing surgical removal of life-threatening brain stem tumors and measured their ionic currents and electromotile responses. The hair cells were either isolated or left in situ in their sensory epithelium and investigated using the tight-seal, whole cell technique. We recorded from both type I and type II vestibular hair cells under voltage clamp and found four voltage-dependent currents, each of which has been reported in hair cells of other animals. Cochlear outer hair cells demonstrated electromotility in response to voltage steps like that seen in rodent animal models. Our results reveal many qualitative similarities to hair cells obtained from other animals and justify continued investigations to explore quantitative differences that may be associated with normal or pathological human sensation.

  14. Nanocrystalline porous TiO2 electrode with ionic liquid impregnated solid polymer electrolyte for dye sensitized solar cells.

    PubMed

    Singh, Pramod K; Kim, Kang-Wook; Kim, Ki-Il; Park, Nam-Gyu; Rhee, Hee-Woo

    2008-10-01

    This communication reports the detailed fabrication of electrodes and solid polymer electrolyte with ionic liquid (IL) as an electrolyte for dye sensitized solar cell (DSSC). Thick porous TiO2 film has been obtained by spreading and sintering TiO2 colloidal paste using "doctor blade" and characterized by SEM, TEM and XRD. The polymer electrolyte was PEO:KI/I2 incorporated with 1-ethyl 3-methylimidazolium thiocyanate (EMImSCN) as IL. Dispersal of IL in the polymer electrolyte improved the ionic conductivity and cell efficiency.

  15. A high throughput method for quantification of cell surface bound and internalized chitosan nanoparticles.

    PubMed

    Tammam, Salma N; Azzazy, Hassan M E; Lamprecht, Alf

    2015-11-01

    Chitosan has become a popular polymer for drug delivery. It's hydro solubility and mild formulation conditions have made it an attractive polymer for macromolecular delivery. Accurate quantification of internalized chitosan nanoparticles (NPs) is imperative for fair assessment of the nano-formulation where it is important to determine the exact amount of drug actually being delivered into the cell, especially for macromolecular drugs where cellular entry is limited by molecule size and/or charge. The preferential affinity of wheat germ agglutinin tagged with fluorescein isothiocyanate (WGA-FITC) to chitosan is exploited in the development of a simple and rapid method for the differentiation between and quantification of cell surface bound and internalized chitosan NPs. The percentage of cell surface bound NPs could be easily determined and corrected NP uptake could be calculated accordingly. The developed method is applicable in several cell lines and has successfully been tested with NPs with different sizes (25 and 150nm) and with very low NP concentrations (20μg/mL). The method will allow for the correct evaluation of chitosan NP uptake and could be further used to evaluate chitosan based nanomedicine and provide guidelines on how to modify NPs for enhanced internalization, and improved drug delivery.

  16. Identification of the protein components of protein-bound polysaccharide (PSK) that interact with NKL cells.

    PubMed

    Jiménez, Eva; Garcia-Lora, Angel; Martinez, Marisol; Garrido, Federico

    2005-04-01

    We identified the protein components of a protein-bound polysaccharide (PSK) that are responsible for the biological function of this immunomodulator in its interaction with NKL cells, an NK-derived cell line previously known to be activated by this extract, obtained from the basidiomycete Coriolus versiocolor. In addition, we show that PSK protein interacts with NKL cells through a different receptor from that used by IL-2. This was deduced from the different molecular weights of the PSK/NKL and IL-2/NKL receptor complexes. We show that PSK is composed of a highly glycosylated 12-kDa protein. Protein-bound polysaccharide interacts in vitro with an NKL receptor of approximately 48 kDa, whereas IL-2 shows a similar interaction with NKL receptor proteins of approximately 64 and 75 kDa. Our results may explain why PSK and IL-2 use completely different intracellular routes for their biological activities in NKL cells-i.e., regulating different PKC isozymes, mitogen-activated protein kinases, and nuclear transcription factors.

  17. Fractal analysis and ionic dependence of endocytotic membrane activity of human breast cancer cells.

    PubMed

    Krasowska, Monika; Grzywna, Zbigniew J; Mycielska, Maria E; Djamgoz, Mustafa B A

    2009-10-01

    The endocytic membrane activities of two human breast cancer cell lines (MDA-MB-231 and MCF-7) of strong and weak metastatic potential, respectively, were studied in a comparative approach. Uptake of horseradish peroxidase was used to follow endocytosis. Dependence on ionic conditions and voltage-gated sodium channel (VGSC) activity were characterized. Fractal methods were used to analyze quantitative differences in vesicular patterning. Digital quantification showed that MDA-MB-231 cells took up more tracer (i.e., were more endocytic) than MCF-7 cells. For the former, uptake was totally dependent on extracellular Na(+) and partially dependent on extracellular and intracellular Ca(2+) and protein kinase activity. Analyzing the generalized fractal dimension (D(q )) and its Legendre transform f(alpha) revealed that under control conditions, all multifractal parameters determined had values greater for MDA-MB-231 compared with MCF-7 cells, consistent with endocytic/vesicular activity being more developed in the strongly metastatic cells. All fractal parameters studied were sensitive to the VGSC blocker tetrodotoxin (TTX). Some of the parameters had a "simple" dependence on VGSC activity, if present, whereby pretreatment with TTX reduced the values for the MDA-MB-231 cells and eliminated the differences between the two cell lines. For other parameters, however, there was a "complex" dependence on VGSC activity. The possible physical/physiological meaning of the mathematical parameters studied and the nature of involvement of VGSC activity in control of endocytosis/secretion are discussed.

  18. Applications and Mechanisms of Ionic Liquids in Whole-Cell Biotransformation

    PubMed Central

    Fan, Lin-Lin; Li, Hong-Ji; Chen, Qi-He

    2014-01-01

    Ionic liquids (ILs), entirely composed of cations and anions, are liquid solvents at room temperature. They are interesting due to their low vapor pressure, high polarity and thermostability, and also for the possibility to fine-tune their physicochemical properties through modification of the chemical structures of their cations or anions. In recent years, ILs have been widely used in biotechnological fields involving whole-cell biotransformations of biodiesel or biomass, and organic compound synthesis with cells. Research studies in these fields have increased from the past decades and compared to the typical solvents, ILs are the most promising alternative solvents for cell biotransformations. However, there are increasing limitations and new challenges in whole-cell biotransformations with ILs. There is little understanding of the mechanisms of ILs’ interactions with cells, and much remains to be clarified. Further investigations are required to overcome the drawbacks of their applications and to broaden their application spectrum. This work mainly reviews the applications of ILs in whole-cell biotransformations, and the possible mechanisms of ILs in microbial cell biotransformation are proposed and discussed. PMID:25007820

  19. Electrical Potentials of Plant Cell Walls in Response to the Ionic Environment1

    PubMed Central

    Shomer, Ilan; Novacky, Anton J.; Pike, Sharon M.; Yermiyahu, Uri; Kinraide, Thomas B.

    2003-01-01

    Electrical potentials in cell walls (ψWall) and at plasma membrane surfaces (ψPM) are determinants of ion activities in these phases. The ψPM plays a demonstrated role in ion uptake and intoxication, but a comprehensive electrostatic theory of plant-ion interactions will require further understanding of ψWall. ψWall from potato (Solanum tuberosum) tubers and wheat (Triticum aestivum) roots was monitored in response to ionic changes by placing glass microelectrodes against cell surfaces. Cations reduced the negativity of ψWall with effectiveness in the order Al3+ > La3+ > H+ > Cu2+ > Ni2+ > Ca2+ > Co2+ > Cd2+ > Mg2+ > Zn2+ > hexamethonium2+ > Rb+ > K+ > Cs+ > Na+. This order resembles substantially the order of plant-root intoxicating effectiveness and indicates a role for both ion charge and size. Our measurements were combined with the few published measurements of ψWall, and all were considered in terms of a model composed of Donnan theory and ion binding. Measured and model-computed values for ψWall were in close agreement, usually, and we consider ψWall to be at least proportional to the actual Donnan potentials. ψWall and ψPM display similar trends in their responses to ionic solutes, but ions appear to bind more strongly to plasma membrane sites than to readily accessible cell wall sites. ψWall is involved in swelling and extension capabilities of the cell wall lattice and thus may play a role in pectin bonding, texture, and intercellular adhesion. PMID:12970506

  20. Ionic currents underlying fast action potentials in the obliquely striated muscle cells of the octopus arm.

    PubMed

    Rokni, Dan; Hochner, Binyamin

    2002-12-01

    The octopus arm provides a unique model for neuromuscular systems of flexible appendages. We previously reported the electrical compactness of the arm muscle cells and their rich excitable properties ranging from fast oscillations to overshooting action potentials. Here we characterize the voltage-activated ionic currents in the muscle cell membrane. We found three depolarization-activated ionic currents: 1) a high-voltage-activated L-type Ca(2+) current, which began activating at approximately -35 mV, was eliminated when Ca(2+) was substituted by Mg(2+), was blocked by nifedipine, and showed Ca(2+)-dependent inactivation. This current had very rapid activation kinetics (peaked within milliseconds) and slow inactivation kinetics (tau in the order of 50 ms). 2) A delayed rectifier K(+) current that was totally blocked by 10 mM TEA and partially blocked by 10 mM 4-aminopyridine (4AP). This current exhibited relatively slow activation kinetics (tau in the order of 15 ms) and inactivated only partially with a time constant of ~150 ms. And 3) a transient A-type K(+) current that was totally blocked by 10 mM 4AP and was partially blocked by 10 mM TEA. This current exhibited very fast activation kinetics (peaked within milliseconds) and inactivated with a time constant in the order of 60 ms. Inactivation of the A-type current was almost complete at -40 mV. No voltage-dependent Na(+) current was found in these cells. The octopus arm muscle cells generate fast (~3 ms) overshooting spikes in physiological conditions that are carried by a slowly inactivating L-type Ca(2+) current.

  1. Computational modeling predicts the ionic mechanism of late-onset responses in unipolar brush cells.

    PubMed

    Subramaniyam, Sathyaa; Solinas, Sergio; Perin, Paola; Locatelli, Francesca; Masetto, Sergio; D'Angelo, Egidio

    2014-01-01

    Unipolar Brush Cells (UBCs) have been suggested to play a critical role in cerebellar functioning, yet the corresponding cellular mechanisms remain poorly understood. UBCs have recently been reported to generate, in addition to early-onset glutamate receptor-dependent synaptic responses, a late-onset response (LOR) composed of a slow depolarizing ramp followed by a spike burst (Locatelli et al., 2013). The LOR activates as a consequence of synaptic activity and involves an intracellular cascade modulating H- and TRP-current gating. In order to assess the LOR mechanisms, we have developed a UBC multi-compartmental model (including soma, dendrite, initial segment, and axon) incorporating biologically realistic representations of ionic currents and a cytoplasmic coupling mechanism regulating TRP and H channel gating. The model finely reproduced UBC responses to current injection, including a burst triggered by a low-threshold spike (LTS) sustained by CaLVA currents, a persistent discharge sustained by CaHVA currents, and a rebound burst following hyperpolarization sustained by H- and CaLVA-currents. Moreover, the model predicted that H- and TRP-current regulation was necessary and sufficient to generate the LOR and its dependence on the intensity and duration of mossy fiber activity. Therefore, the model showed that, using a basic set of ionic channels, UBCs generate a rich repertoire of bursts, which could effectively implement tunable delay-lines in the local microcircuit.

  2. Fluorescence anisotropy decay of ethidium bound to nucleosome core particles. 1. Rotational diffusion indicates an extended structure at low ionic strength

    SciTech Connect

    Brown, D.W.; Libertini, L.J.; Small, E.W. )

    1991-05-28

    The fluorescence decay of ethidium intercalated into the DNA of nucleosome core particles increases in average lifetime from about 22 ns in H{sub 2}O to about 39 ns in D{sub 2}O. This increase, combined with the acquisiton of large amounts of data, allows measurement of anisotropy decays out to more than 350 ns. The overall slow rotational motions of the core particle may thereby be more clearly distinguished from the faster torsional motions of the DNA. In 10 mM NaCl at 20{degrees}C, the authors recover a long correlation time of 198 ns in D{sub 2}O (159 ns when corrected to a viscosity of 1.002 cP), in agreement with the value of 164 ns obtained in H{sub 2}O. These values are consistent with hydrodynamic calculations based on the expected size and shape of the hydrated particle. To support their conclusion that this long correlation time derives from Brownian rotational diffusion, they show that the value is directly proportional to the viscosity and inversely proportional to the temperature. No significant changes in the rotational correlation time are observed between 1 and 500 mM ionic strength. Below 1 mM, the particle undergoes the low-salt transition as measured by steady-state tyrosine fluorescence anisotropy. However, they observe little change in shape until the ionic strength is decreased below {approximately}0.2 mM, where the correlation time increases nearly 2-fold, indicating that the particle has opened up into an extended form. They have previously shown that the transition becomes nonreversible below 0.2 mM salt.

  3. The flexible structure of the K24S28 region of Leucine-Rich Amelogenin Protein (LRAP) bound to apatites as a function of surface type, calcium, mutation, and ionic strength

    SciTech Connect

    Lu, Junxia; Burton, Sarah D.; Xu, Yimin; Buchko, Garry W.; Shaw, Wendy J.

    2014-07-11

    Leucine-Rich Amelogenin Protein (LRAP) is a member of the amelogenin family of biomineralization proteins, proteins which play a critical role in enamel formation. Recent studies have revealed the structure and orientation of the N- and C-terminus of LRAP bound to hydroxyapatite (HAP), a surface used as an analog of enamel. The structure of one region, K24 to S28, was found to be sensitive to phosphorylation of S16, the only naturally observed site of serine phosphorylation in LRAP, suggesting that the residues from K24 to S28 may sit at a key region of structural flexibility and play a role in the protein’s function. In this work, we investigated the sensitivity of the structure and orientation of this region when bound to HAP as a function of several factors which may vary during enamel formation to influence structure: the ionic strength (0.05 M, 0.15 M, 0.2 M), the calcium concentration (0.07 mM and 0.4 mM), and the surface to which it is binding (HAP and carbonated apatite (CAP), a more direct mimic of enamel). A naturally occurring mutation found in amelogenin (T21I), was also investigated. The structure in the K24S28 region of the protein was found to be sensitive to these conditions, with the CAP surface and excess Ca2+ (8:1 [Ca2+]:[LRAP-K24S28(+P)]) resulting in a much tighter helix, while low ionic strength relaxed the helical structure. Higher ionic strength and the point mutation did not result in any structural change in this region. The distance of the backbone of K24 from the surface was most sensitive to excess Ca2+ and in the T21I-mutation. Collectively, these data suggest that the protein is able to accommodate structural changes while maintaining its interaction with the surface, and provides further evidence of the structural sensitivity of the K24 to S28 region, a sensitivity that may contribute to function in biomineralization. This research was supported by NIH-NIDCR Grant DE-015347. The research was performed at the Pacific Northwest

  4. The flexible structure of the K24S28 region of Leucine-Rich Amelogenin Protein (LRAP) bound to apatites as a function of surface type, calcium, mutation, and ionic strength.

    PubMed

    Lu, Jun-Xia; Burton, Sarah D; Xu, Yimin S; Buchko, Garry W; Shaw, Wendy J

    2014-01-01

    Leucine-Rich Amelogenin Protein (LRAP) is a member of the amelogenin family of biomineralization proteins, proteins which play a critical role in enamel formation. Recent studies have revealed the structure and orientation of the N- and C-terminus of LRAP bound to hydroxyapatite (HAP), a surface used as an analog of enamel. The structure of one region, K24 to S28, was found to be sensitive to phosphorylation of S16, the only naturally observed site of serine phosphorylation in LRAP, suggesting that K24S28 may sit at a key region of structural flexibility and play a role in the protein's function. In this work, we investigated the sensitivity of the structure and orientation of this region when bound to HAP as a function of several factors which may vary during enamel formation to influence structure: the ionic strength (0.05, 0.15, 0.2 M), the calcium concentration (0.07 and 0.4 mM), and the surface to which it is binding [HAP and carbonated apatite (CAP), a more direct mimic of enamel]. A naturally occurring mutation found in amelogenin (T21I) was also investigated. The structure in the K24S28 region of the protein was found to be sensitive to these conditions, with the CAP surface and excess Ca(2+) (8:1 [Ca(2+)]:[LRAP-K24S28(+P)]) resulting in a tighter helix, while low ionic strength relaxed the helical structure. Higher ionic strength and the point mutation did not result in any structural change in this region. The distance of the backbone of K24 from the surface was most sensitive to excess Ca(2+) and in the T21I-mutation. Collectively, these data suggest that phosphorylated LRAP is able to accommodate structural changes while maintaining its interaction with the surface, and provides further evidence of the structural sensitivity of the K24S28 region, a sensitivity that may contribute to function in biomineralization.

  5. Cell wall-bound ultraviolet-screening compounds explain the high ultraviolet tolerance of the Antarctic moss, Ceratodon purpureus.

    PubMed

    Clarke, Laurence J; Robinson, Sharon A

    2008-01-01

    * Studies of ultraviolet (UV) light-induced DNA damage in three Antarctic moss species have shown Ceratodon purpureus to be the most UV tolerant, despite containing lower concentrations of methanol-soluble UV-screening compounds than the co-occurring Bryum pseudotriquetrum. * In this study, alkali extraction of cell wall-bound phenolics, combined with methanol extraction of soluble phenolics, was used to determine whether cell wall-bound UV screens explain the greater UV tolerance of C. purpureus. * The combined pool of UV screens was similar in B. pseudotriquetrum and C. purpureus, but whilst B. pseudotriquetrum had almost equal concentrations of MeOH-soluble and alkali-extractable cell wall-bound UV-screening compounds, in C. purpureus the concentration of cell wall-bound screening compounds was six times higher than the concentration of MeOH-soluble UV screens. The Antarctic endemic Schistidium antarctici possessed half the combined pool of UV screens of the other species but, as in C. purpureus, these were predominantly cell wall bound. Confocal microscopy confirmed the localization of UV screens in each species. * Greater investment in cell wall-bound UV screens offers C. purpureus a more spatially uniform, and potentially more effective, UV screen. Schistidium antarctici has the lowest UV-screening potential, indicating that this species may be disadvantaged under continuing springtime ozone depletion. Cell wall compounds have not previously been quantified in bryophytes but may be an important component of the UV defences of lower plants.

  6. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells.

    PubMed

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

  7. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells

    PubMed Central

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P.

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag. PMID:26061169

  8. Membrane-bound alkaline phosphatase from ectopic mineralization and rat bone marrow cell culture.

    PubMed

    Simão, Ana Maria S; Beloti, Márcio M; Cezarino, Rodrigo M; Rosa, Adalberto Luiz; Pizauro, João M; Ciancaglini, Pietro

    2007-04-01

    Cells from rat bone marrow exhibit the proliferation-differentiation sequence of osteoblasts, form mineralized extracellular matrix in vitro and release alkaline phosphatase into the medium. Membrane-bound alkaline phosphatase was obtained by method that is easy to reproduce, simpler and fast when compared with the method used to obtain the enzyme from rat osseous plate. The membrane-bound alkaline phosphatase from cultures of rat bone marrow cells has a MW(r) of about 120 kDa and specific PNPP activity of 1200 U/mg. The ecto-enzyme is anchored to the plasma membrane by the GPI anchor and can be released by PIPLC (selective treatment) or polidocanol (0.2 mg/mL protein and 1% (w/v) detergent). The apparent optimum pH for PNPP hydrolysis by the enzyme was pH 10. This fraction hydrolyzes ATP (240 U/mg), ADP (350 U/mg), glucose 1-phosphate (1100 U/mg), glucose 6-phosphate (340 U/mg), fructose 6-phosphate (460 U/mg), pyrophosphate (330 U/mg) and beta-glycerophosphate (600 U/mg). Cooperative effects were observed for the hydrolysis of PPi and beta-glycerophosphate. PNPPase activity was inhibited by 0.1 mM vanadate (46%), 0.1 mM ZnCl2 (68%), 1 mM levamisole (66%), 1 mM arsenate (44%), 10 mM phosphate (21%) and 1 mM theophylline (72%). We report the biochemical characterization of membrane-bound alkaline phosphatase obtained from rat bone marrow cells cultures, using a method that is simple, rapid and easy to reproduce. Its properties are compared with those of rat osseous plate enzyme and revealed that the alkaline phosphatase obtained has some kinetics and structural behaviors with higher levels of enzymatic activity, facilitating the comprehension of the mineralization process and its function.

  9. Design and application of a novel ionic liquid with the property of strengthening coenzyme regeneration for whole-cell bioreduction in an ionic liquid-distilled water medium.

    PubMed

    Li, Jun; Wang, Pu; Huang, Jin; Sun, Jia

    2015-01-01

    Focusing on the task-specific properties of ionic liquids (ILs), a novel IL was designed by combining the quaternary ammonium cationic surfactant, [N1,1,1,1](+), with benign amino acid anion ([Cys](-)), and was successfully employed in whole-cell-catalyzed bioreduction by Trichodermaasperellum ZJPH0810 using an ionic liquid-distilled water medium. As expected, based on better understanding about the effects of ILs' characteristics of cations and anions on T. asperellum ZJPH0810-catalyzed bioreduction and the optimization of reaction parameters, the developed tetramethylammonium cysteine ([N1,1,1,1][Cys])-containing system is more efficient for the asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone to (R)-[3,5-bis(trifluoromethyl)phenyl] ethanol by whole-cell catalysis in contrast to that in monophasic aqueous system. Herein, a new biotechnological application for designed type of ILs is proposed due to its novel property of strengthening coenzyme regeneration during the bioreduction process. The designed IL [N1,1,1,1][Cys] was also evaluated in Candidatropicalis 104-catalyzed bioreduction to board its application, with remarkable success.

  10. Ionic and osmotic equilibria of human red blood cells treated with nystatin

    PubMed Central

    1979-01-01

    Human red blood cells have been incubated in the presence of nystatin, which allows Na and K, as well as Cl and pH to equilibrate rapidly when cell volume is set with external impermeant sucrose. The intracellular mean ionic activity coefficients, relative to values in the extracellular solution, for KCl and NaCl are 1.01 +/- 0.02 and 0.99 +/- 0.02 (SD, n = 10), respectively, and are independent of external pH, pH o, and of [sucrose]o. With nystatin the dependence of red cell volume on [sucrose]o deviates from ideal osmotic behavior by as much as a factor of three. A virial equation for the osmotic coefficient, phi, of human hemoglobin, Hb, accounts for the cell volumes, and is the same as that which describes Adair's measurements of phi Hb for Hb isolated from sheep and ox bloods. In the presence of nystatin the slope of the acid-base titration curve of the cells is independent of cell volume, implying that the charge on impermeant cellular solutes is independent of Hb concentration at constant pH. By modifying the Jacobs-stewart equations (1947. J. Cell. Comp. Physiol. 30: 79--103) with the osmotic coefficients of Hb and of salts, a nonideal thermodynamic model has been devised which predicts equilibrium Donnan ratios and red cell volume from the composition of the extracellular solution and from certain parameters of the cells. In addition to accounting for the dependence of cell volume on osmotic pressure, the model also describes accurately the dependence of Donnan ratios and cell volumes on pHo either in the presence or absence of nystatin. PMID:490141

  11. Association between cell-bound blood amyloid-β(1–40) levels and hippocampus volume

    PubMed Central

    2014-01-01

    Introduction The identification of early, preferably presymptomatic, biomarkers and true etiologic factors for Alzheimer’s disease (AD) is the first step toward establishing effective primary and secondary prevention programs. Consequently, the search for a relatively inexpensive and harmless biomarker for AD continues. Despite intensive research worldwide, to date there is no definitive plasma or blood biomarker indicating high or low risk of conversion to AD. Methods Magnetic resonance imaging and β-amyloid (Aβ) levels in three blood compartments (diluted in plasma, undiluted in plasma and cell-bound) were measured in 96 subjects (33 with mild cognitive impairment, 14 with AD and 49 healthy controls). Pearson correlations were completed between 113 regions of interest (ROIs) (45 subcortical and 68 cortical) and Aβ levels. Pearson correlation analyses adjusted for the covariates age, sex, apolipoprotein E (ApoE), education and creatinine levels showed neuroimaging ROIs were associated with Aβ levels. Two statistical methods were applied to study the major relationships identified: (1) Pearson correlation with phenotype added as a covariate and (2) a meta-analysis stratified by phenotype. Neuroimaging data and plasma Aβ measurements were taken from 630 Alzheimer’s Disease Neuroimaging Initiative (ADNI) subjects to be compared with our results. Results The left hippocampus was the brain region most correlated with Aβ(1–40) bound to blood cell pellets (partial correlation (pcor) = −0.37, P = 0.0007) after adjustment for the covariates age, gender and education, ApoE and creatinine levels. The correlation remained almost the same (pcor = −0.35, P = 0.002) if phenotype is also added as a covariate. The association between both measurements was independent of cognitive status. The left hemisphere entorhinal cortex also correlated with Aβ(1–40) cell-bound fraction. AB128 and ADNI plasma Aβ measurements were not related to any brain

  12. Ionic conductivity measurement in magnesium aluminate spinel and solid state galvanic cell with magnesium aluminate electrolyte

    NASA Astrophysics Data System (ADS)

    Lee, Myongjai

    This thesis work is about the experimental measurement of electronic and ionic conductivities in the MgAl2O4 spinel at 500˜600°C range and exploring the fundamental origin of solid-state galvanic cell behavior in the cell of Al|MgAl2O4|Mg, Al|MgAl2O 4|C, and Mg|MgAl2O4|C, in which at least one metal electrode in common with the composition of the electrolyte. For the electronic conductivity measurement, we have used the ion-blocking Gold and Carbon electrodes which are inert with both Mg and Al ions to suppress the ionic conduction from the total conduction. DC polarization method was used to measure the conduction through Au|MgAl2O4|Au and C|MgAl2O4|C specimens. The measured electrical conductivity using Au|MgAl2O4|Au and C|MgAl2O4|C specimens showed 10-9.3 ˜ 10-8.4 (O·cm) -1 at 600˜720°C range following the Arrhenius-type relation. These conductivity data are in agreement with reported data obtained from Pt and Ag ion-blocking electrodes deposited on MgAl2O4 specimens. For the ionic conductivity measurement, we have used the non-blocking Al and Mg electrodes for Al and Mg ionic conductivities, respectively. Ionic conductivity measurement of Al and Mg in separate manner has not been reported yet. In both Al|MgAl2O4|Al and Mg|MgAl2O 4|Mg specimens, gradual increase of conduction was observed once at the initial period before it reaches the steady state conduction. By DC method on the range of 580˜650°C, steady state Al ionic conductivity was measured from Al|MgAl2O4|Al specimen showing 10 -7.7 ˜ 10-6.8 (O·cm)-1 with the activation energy of 1.9eV in sigma = sigma0 exp-QRT formula. There was no difference in the conductivity by the change of the atmosphere from 5%H2 + 95%N2 mixed gas to pure Ar gas. So it was confirmed that the oxygen defect chemistry did not play a role. For Mg ionic conductivity Mg|MgAl2O4|Mg specimen was used and the measured conductivity shows 10-6.7 ˜ 10-4.4 (O·cm)-1 at 400˜550°C with the activation energy of 1.44eV at Ar gas

  13. Neurotoxic Mutants of the Prion Protein Induce Spontaneous Ionic Currents in Cultured Cells*

    PubMed Central

    Solomon, Isaac H.; Huettner, James E.; Harris, David A.

    2010-01-01

    The mechanisms by which prions kill neurons and the role of the cellular prion protein in this process are enigmatic. Insight into these questions is provided by the neurodegenerative phenotypes of transgenic mice expressing prion protein (PrP) molecules with deletions of conserved amino acids in the central region. We report here that expression in transfected cells of the most toxic of these PrP deletion mutants (Δ105–125) induces large, spontaneous ionic currents that can be detected by patch-clamping techniques. These currents are produced by relatively non-selective, cation-permeable channels or pores in the cell membrane and can be silenced by overexpression of wild-type PrP, as well as by treatment with a sulfated glycosaminoglycan. Similar currents are induced by PrP molecules carrying several different point mutations in the central region that cause familial prion diseases in humans. The ionic currents described here are distinct from those produced in artificial lipid membranes by synthetic peptides derived from the PrP sequence because they are induced by membrane-anchored forms of PrP that are synthesized by cells and that are found in vivo. Our results indicate that the neurotoxicity of some mutant forms of PrP is attributable to enhanced ion channel activity and that wild-type PrP possesses a channel-silencing activity. Drugs that block PrP-associated channels or pores may therefore represent novel therapeutic agents for treatment of patients with prion diseases. PMID:20573963

  14. A computational model with ionic conductances for the fusiform cell of the dorsal cochlear nucleus.

    PubMed

    Kim, D O; Ghoshal, S; Khant, S L; Parham, K

    1994-09-01

    A computational model of a fusiform cell of the dorsal cochlear nucleus was developed. The results of model simulations are compared with the results of in vitro experimental observations obtained by other investigators. The structure of the present model is similar to that of Hodgkin-Huxley [J. Physiol. 117, 500-544 (1952)]. The model incorporates five nonlinear voltage-dependent conductances (three potassium and two sodium types) and their associated equilibrium-potential batteries, a leakage conductance, the membrane capacitance, and a current source. Model responses were obtained under both current- and voltage-clamp conditions. When a hyper- and depolarizing current sequence was applied [Manis, J. Neurosci. 10, 2338-2351 (1990)], the cell model was able to reproduce builduplike and pauserlike discharge patterns closely resembling Manis' observations. A transient "A"-type potassium conductance in the model played a major role in generating this phenomenon. The model predicts that blocking the "A" conductance should convert a builduplike or pauserlike pattern into a sustained regular pattern. A persistent sodium conductance in the model played the main role in reproducing: Spontaneous regular discharge; a discharge after a long latency under a long small (+0.025 nA) current; and nonlinear voltage-current characteristics with positive currents. Usefulness of the model can be seen as follows: (1) Several sets of experimental observations can be integrated into a common framework; (2) possible roles of different ionic conductances postulated to be present in the cell can be inferred by observing the model behavior with the conductances intact or blocked; and (3) time courses of ionic currents and conductance values obtained from the model under current- and voltage-clamp conditions can serve as predictions to be tested in future experimental studies.

  15. Effect of varied ionic calcium on human adipose-derived stem cell mineralization.

    PubMed

    McCullen, Seth D; Zhan, Jackie; Onorato, Maureen L; Bernacki, Susan H; Loboa, Elizabeth G

    2010-06-01

    Human adipose-derived stem cells (hASCs) are a relatively abundant and accessible stem cell source with multilineage differentiation capability and have great potential for bone tissue engineering applications. The success of bone tissue engineering is intimately linked with the production of a mineralized matrix that mimics the natural mineral present within native bone. In this study, we examined the effects of ionic calcium levels of 1.8 (normal concentration in cell culture medium), 8, and 16 mM on hASCs seeded in both two-dimensional monolayer and three-dimensional electrospun scaffolds and cultured in either complete growth medium (CGM) or osteogenic differentiation medium (ODM). The impact of calcium supplementation on hASC viability, proliferation, and mineral deposition was determined. hASCs remained viable for all experimental treatments. hASC proliferation increased with the addition of 8 mM Ca(2+) CGM, but decreased for the 16 mM Ca(2+) CGM treatment. Materials deposited by hASCs were analyzed using four techniques: (1) histological staining with Alizarin Red S, (2) calcium quantification, (3) Fourier transform infrared spectroscopy, and (4) wide-angle X-ray diffraction. Mineral deposition was significantly enhanced under both growth and osteogenic medium conditions by increasing extracellular Ca(2+). The greatest mineral deposition occurred in the ODM 8 mM Ca(2+) treatment group. Fourier transform infrared spectroscopy analysis indicated that elevated calcium concentrations of 8 mM Ca(2+) significantly increased both PO(4) amount and PO(4) to protein ratio for ODM. X-ray diffraction indicated that mineral produced with elevated Ca(2+) in both CGM and ODM had a crystalline structure characteristic of hydroxyapatite. Ionic calcium should be considered a potent regulator in hASC mineralization and could serve as a potential treatment for inducing prompt ossification of hASC-seeded scaffolds for bone tissue engineering prior to implantation.

  16. Characterization of ionic currents of cells of the subfornical organ that project to the supraoptic nuclei

    NASA Technical Reports Server (NTRS)

    Johnson, R. F.; Beltz, T. G.; Jurzak, M.; Wachtel, R. E.; Johnson, A. K.

    1999-01-01

    The subfornical organ (SFO) is a forebrain structure that converts peripheral blood-borne signals reflecting the hydrational state of the body to neural signals and then through efferent fibers conveys this information to several central nervous system structures. One of the forebrain areas receiving input from the SFO is the supraoptic nucleus (SON), a source of vasopressin synthesis and control of release from the posterior pituitary. Little is known of the transduction and transmission processes by which this conversion of systemic information to brain input occurs. As a step in elucidating these mechanisms, the present study characterized the ionic currents of dissociated cells of the SFO that were identified as neurons that send efferents to the SON. A retrograde tracer was injected into the SON area in eleven-day-old rats. After three days for retrograde transport of the label, the SFOs of these animals were dissociated and plated for tissue culture. The retrograde tracer was used to identify the soma of SFO cells projecting to the SON so that voltage-dependent ionic currents using whole-cell voltage clamp methods could be studied. The three types of currents in labeled SFO neurons were characterized as a 1) rapid, transient inward current that can be blocked by tetrodotoxin (TTX) characteristic of a sodium current; 2) slow-onset sustained outward current that can be blocked by tetraethylammonium (TEA) characteristic of a delayed rectifier potassium current; and 3) remaining outward current that has a rapid-onset and transient characteristic of a potassium A-type current. Copyright 1999 Elsevier Science B.V.

  17. Characterization of ionic currents of cells of the subfornical organ that project to the supraoptic nuclei

    NASA Technical Reports Server (NTRS)

    Johnson, R. F.; Beltz, T. G.; Jurzak, M.; Wachtel, R. E.; Johnson, A. K.

    1999-01-01

    The subfornical organ (SFO) is a forebrain structure that converts peripheral blood-borne signals reflecting the hydrational state of the body to neural signals and then through efferent fibers conveys this information to several central nervous system structures. One of the forebrain areas receiving input from the SFO is the supraoptic nucleus (SON), a source of vasopressin synthesis and control of release from the posterior pituitary. Little is known of the transduction and transmission processes by which this conversion of systemic information to brain input occurs. As a step in elucidating these mechanisms, the present study characterized the ionic currents of dissociated cells of the SFO that were identified as neurons that send efferents to the SON. A retrograde tracer was injected into the SON area in eleven-day-old rats. After three days for retrograde transport of the label, the SFOs of these animals were dissociated and plated for tissue culture. The retrograde tracer was used to identify the soma of SFO cells projecting to the SON so that voltage-dependent ionic currents using whole-cell voltage clamp methods could be studied. The three types of currents in labeled SFO neurons were characterized as a 1) rapid, transient inward current that can be blocked by tetrodotoxin (TTX) characteristic of a sodium current; 2) slow-onset sustained outward current that can be blocked by tetraethylammonium (TEA) characteristic of a delayed rectifier potassium current; and 3) remaining outward current that has a rapid-onset and transient characteristic of a potassium A-type current. Copyright 1999 Elsevier Science B.V.

  18. Tightly Bound Binary Toxin in the Cell Wall of Bacillus sphaericus

    PubMed Central

    Klein, Daniela; Uspensky, Igor; Braun, Sergei

    2002-01-01

    We have shown that urea-extracted cell wall of entomopathogenic Bacillus sphaericus 2297 and some other strains is a potent larvicide against Culex pipiens mosquitoes, with 50% lethal concentrations comparable to that of the well-known B. sphaericus binary toxin, with which it acts synergistically. The wall toxicity develops in B. sphaericus 2297 cultures during the late logarithmic stage, earlier than the appearance of the binary toxin crystal. It disappears with sporulation when the binary toxin activity reaches its peak. Disruption of the gene for the 42-kDa protein (P42) of the binary toxin abolishes both cell wall toxicity and crystal formation. However, the cell wall of B. sphaericus 2297, lacking P42, kills C. pipiens larvae when mixed with Escherichia coli cells expressing P42. Thus, the cell wall toxicity in strongly toxic B. sphaericus strains must be attributed to the presence in the cell wall of tightly bound 51-kDa (P51) and P42 binary toxin proteins. The synergism between binary toxin crystals and urea-treated cell wall preparations reflects suboptimal distribution of binary toxin subunits in both compartments. Binary toxin crystal is slightly deficient in P51, while cell wall is lacking in P42. PMID:12089007

  19. Tightly bound binary toxin in the cell wall of Bacillus sphaericus.

    PubMed

    Klein, Daniela; Uspensky, Igor; Braun, Sergei

    2002-07-01

    We have shown that urea-extracted cell wall of entomopathogenic Bacillus sphaericus 2297 and some other strains is a potent larvicide against Culex pipiens mosquitoes, with 50% lethal concentrations comparable to that of the well-known B. sphaericus binary toxin, with which it acts synergistically. The wall toxicity develops in B. sphaericus 2297 cultures during the late logarithmic stage, earlier than the appearance of the binary toxin crystal. It disappears with sporulation when the binary toxin activity reaches its peak. Disruption of the gene for the 42-kDa protein (P42) of the binary toxin abolishes both cell wall toxicity and crystal formation. However, the cell wall of B. sphaericus 2297, lacking P42, kills C. pipiens larvae when mixed with Escherichia coli cells expressing P42. Thus, the cell wall toxicity in strongly toxic B. sphaericus strains must be attributed to the presence in the cell wall of tightly bound 51-kDa (P51) and P42 binary toxin proteins. The synergism between binary toxin crystals and urea-treated cell wall preparations reflects suboptimal distribution of binary toxin subunits in both compartments. Binary toxin crystal is slightly deficient in P51, while cell wall is lacking in P42.

  20. Neoplastic transformation of rat liver epithelial cells is enhanced by non-transferrin-bound iron

    PubMed Central

    Messner, Donald J; Kowdley, Kris V

    2008-01-01

    Background Iron overload is associated with liver toxicity, cirrhosis, and hepatocellular carcinoma in humans. While most iron circulates in blood as transferrin-bound iron, non-transferrin-bound iron (NTBI) also becomes elevated and contributes to toxicity in the setting of iron overload. The mechanism for iron-related carcinogenesis is not well understood, in part due to a shortage of suitable experimental models. The primary aim of this study was to investigate NTBI-related hepatic carcinogenesis using T51B rat liver epithelial cells, a non-neoplastic cell line previously developed for carcinogenicity and tumor promotion studies. Methods T51B cells were loaded with iron by repeated addition of ferric ammonium citrate (FAC) to the culture medium. Iron internalization was documented by chemical assay, ferritin induction, and loss of calcein fluorescence. Proliferative effects were determined by cell count, toxicity was determined by MTT assay, and neoplastic transformation was assessed by measuring colony formation in soft agar. Cyclin levels were measured by western blot. Results T51B cells readily internalized NTBI given as FAC. Within 1 week of treatment at 200 μM, there were significant but well-tolerated toxic effects including a decrease in cell proliferation (30% decrease, p < 0.01). FAC alone induced little or no colony formation in soft agar. In contrast, FAC addition to cells previously initiated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) resulted in a concentration dependent increase in colony formation. This was first detected at 12 weeks of FAC treatment and increased at longer times. At 16 weeks, colony formation increased more than 10 fold in cells treated with 200 μM FAC (p < 0.001). The iron chelator desferoxamine reduced both iron uptake and colony formation. Cells cultured with 200 μM FAC showed decreased cyclin D1, decreased cyclin A, and increased cyclin B1. Conclusion These results establish NTBI as a tumor promoter in T51B rat liver

  1. Velocity valleys enable efficient capture and spatial sorting of nanoparticle-bound cancer cells

    NASA Astrophysics Data System (ADS)

    Besant, Justin D.; Mohamadi, Reza M.; Aldridge, Peter M.; Li, Yi; Sargent, Edward H.; Kelley, Shana O.

    2015-03-01

    The development of strategies for isolating rare cells from complex matrices like blood is important for a wide variety of applications including the analysis of bloodborne cancer cells, infectious pathogens, and prenatal testing. Due to their high colloidal stability and surface-to-volume ratio, antibody-coated magnetic nanoparticles are excellent labels for cellular surface markers. Unfortunately, capture of nanoparticle-bound cells at practical flow rates is challenging due to the small volume, and thus low magnetic susceptibility, of magnetic nanoparticles. We have developed a means to capture nanoparticle-labeled cells using microstructures which create pockets of locally low linear velocity, termed velocity valleys. Cells that enter a velocity valley slow down momentarily, allowing the magnetic force to overcome the reduced drag force and trap the cells. Here, we describe a model for this mechanism of cell capture and use this model to guide the rational design of a device that efficiently captures rare cells and sorts them according to surface expression in complex matrices with greater than 10 000-fold specificity. By analysing the magnetic and drag forces on a cell, we calculate a threshold linear velocity for capture and relate this to the capture efficiency. We find that the addition of X-shaped microstructures enhances capture efficiency 5-fold compared to circular posts. By tuning the linear velocity, we capture cells with a 100-fold range of surface marker expression with near 100% efficiency and sort these cells into spatially distinct zones. By tuning the flow channel geometry, we reduce non-specific cell adhesion by 5-fold.The development of strategies for isolating rare cells from complex matrices like blood is important for a wide variety of applications including the analysis of bloodborne cancer cells, infectious pathogens, and prenatal testing. Due to their high colloidal stability and surface-to-volume ratio, antibody-coated magnetic

  2. Fluorescence resonance energy transfer on single living cells. Application to binding of monovalent haptens to cell-bound immunoglobulin E.

    PubMed Central

    Kubitscheck, U; Kircheis, M; Schweitzer-Stenner, R; Dreybrodt, W; Jovin, T M; Pecht, I

    1991-01-01

    We have determined the specific binding of 2,4-dinitrophenyl (DNP)-haptens to two different monoclonal immunoglobulin (IgE) molecules bound to Fc epsilon-receptors on the cell surface of single, living rat basophilic leukemia cells subclone 2H3 cells. The measurements were performed at 4 degrees, 15 degrees, and 25 degrees C using a recently developed technique that permits the quantitative determination of fluorescence resonance energy transfer between two fluorophores on single cells in a microscope from the photobleaching kinetics of the donor fluorophore. We introduce here a method for performing binding studies on individual attached cells. At 25 degrees C, the titration studies yielded equilibrium binding constants Kint of 9 x 10(8), 8 x 10(8), and 8 x 10(7) M-1 for the monovalent haptens N-2,4-DNP-epsilon-amino-n-caproic acid, N epsilon-2,4-DNP-L-lysine, and N-2,4-DNP-gamma-amino-n-butyric acid, respectively. Our data indicate that the affinity constants for the first two haptens binding to IgE on adherent cells are 4 to 11 times larger than that of the corresponding values obtained by fluorescence quenching experiments with the same haptens and IgE molecules either in solution or bound to cells in suspension. PMID:1832974

  3. Membrane-bound Dickkopf-1 in Foxp3(+) regulatory T cells suppresses T-cell-mediated autoimmune colitis.

    PubMed

    Chae, Wook-Jin; Park, Jong-Hyun; Henegariu, Octavian; Yilmaz, Saliha; Hao, Liming; Bothwell, Alfred L M

    2017-10-01

    Induction of tolerance is a key mechanism to maintain or to restore immunological homeostasis. Here we show that Foxp3(+) regulatory T (Treg) cells use Dickkopf-1 (DKK-1) to regulate T-cell-mediated tolerance in the T-cell-mediated autoimmune colitis model. Treg cells from DKK-1 hypomorphic doubleridge mice failed to control CD4(+) T-cell proliferation, resulting in CD4 T-cell-mediated autoimmune colitis. Thymus-derived Treg cells showed a robust expression of DKK-1 but not in naive or effector CD4 T cells. DKK-1 expression in Foxp3(+) Treg cells was further increased upon T-cell receptor stimulation in vitro and in vivo. Interestingly, Foxp3(+) Treg cells expressed DKK-1 in the cell membrane and the functional inhibition of DKK-1 using DKK-1 monoclonal antibody abrogated the suppressor function of Foxp3(+) Treg cells. DKK-1 expression was dependent on de novo protein synthesis and regulated by the mitogen-activated protein kinase pathway but not by the canonical Wnt pathway. Taken together, our results highlight membrane-bound DKK-1 as a novel Treg-derived mediator to maintain immunological tolerance in T-cell-mediated autoimmune colitis. © 2017 The Authors. Immunology Published by John Wiley & Sons Ltd.

  4. Modulation of Ionic Channels and Insulin Secretion by Drugs and Hormones in Pancreatic Beta Cells.

    PubMed

    Velasco, Myrian; Díaz-García, Carlos Manlio; Larqué, Carlos; Hiriart, Marcia

    2016-09-01

    Pancreatic beta cells, unique cells that secrete insulin in response to an increase in glucose levels, play a significant role in glucose homeostasis. Glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells has been extensively explored. In this mechanism, glucose enters the cells and subsequently the metabolic cycle. During this process, the ATP/ADP ratio increases, leading to ATP-sensitive potassium (KATP) channel closure, which initiates depolarization that is also dependent on the activity of TRP nonselective ion channels. Depolarization leads to the opening of voltage-gated Na(+) channels (Nav) and subsequently voltage-dependent Ca(2+) channels (Cav). The increase in intracellular Ca(2+) triggers the exocytosis of insulin-containing vesicles. Thus, electrical activity of pancreatic beta cells plays a central role in GSIS. Moreover, many growth factors, incretins, neurotransmitters, and hormones can modulate GSIS, and the channels that participate in GSIS are highly regulated. In this review, we focus on the principal ionic channels (KATP, Nav, and Cav channels) involved in GSIS and how classic and new proteins, hormones, and drugs regulate it. Moreover, we also discuss advances on how metabolic disorders such as metabolic syndrome and diabetes mellitus change channel activity leading to changes in insulin secretion.

  5. Biomacromolecular-based ionic-covalent hydrogels for cell encapsulation: The atelocollagen - Oxidized polysaccharides couples.

    PubMed

    Luca, Andreea; Maier, Vasilica; Maier, Stelian S; Butnaru, Maria; Danu, Maricel; Ibanescu, Constanta; Pinteala, Mariana; Popa, Marcel

    2017-08-01

    Mixed crosslinked networks of ionic-covalent entanglement type were prepared starting from ternary mixtures of atelocollagen (aK; as fibrillary matrix generator), sodium hyaluronate (NaHyal; a microfibrillation assistant), and oxidized polysaccharides (OxPolys; as both cross-linkers and matrix fillers), and were tested as hydrogels for eukaryotic cell encapsulation. Either oxidized gellan (GellOx) or pullulan (PullOx) were used. An original procedure and optimal hydrogel recipes were developed to encapsulate fibroblasts and adipose-derived stem cells, while preserving their viability and proliferative ability during ex vivo temporarily storage. Physical-chemical, rheological, and biocompatibility properties of the prepared hydrogels were compared against the classic alginate hydrogel used for cell encapsulation. A larger range of material characteristics (from lax to stiff) and better laboratory maneuverability were demonstrated, which permit to design appropriate compositions for particular cell types. All hydrogels undergo fast liquefaction at temperatures between 42 and 50°C, permitting the cell release after a short innocuous thermal shock. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Competing rearrangement reactions in small gas-phase ionic complexes: The internal SN2 and nitro-nitrite rearrangements in nitroalkane proton-bound pairs

    NASA Astrophysics Data System (ADS)

    Poon, Clement; Mayer, Paul M.

    2006-09-01

    The dissociation of metastable proton-bound pairs, (R1NO2)(R2NO2)H+ (R1 and R2 = CH3, CH3CH2, (CH3)2CH and (CH3)3C) have been investigated by mass spectrometry and density functional theory calculations. The proton-bound pairs can dissociate via hydrogen-bond cleavage into protonated and neutral nitroalkanes. Methyl substitution of the nitroalkanes (R1 and R2 = (CH3)2CH, (CH3)3C) permits a rearrangement process to compete with the H-bond cleavage on the microsecond timescale. The rearrangement reaction results in an isomer that then loses nitrous acid and involves an internal SN2-type mechanism in which (R1NO2)(R2NO2)H+ isomerizes to R1NO2...R2NO2H+ via TS1 and then subsequently to R1NO2R2+...HONO via TS2 prior to dissociation. The process is favoured by stabilization of the charge in TS2 by methyl substitution. The stability of the t-butyl ion changes the mechanism in ((CH3)3CNO2)2H+ to one that involves a two-step alkyl cation transfer. An investigation of nitro-nitrite rearrangement in protonated nitroalkanes at the B3-LYP/6-31 + G(d) level of theory found that the rearrangement barrier is lowered to the point that (CH3)3CNO2H+ can easily interconvert into (CH3)3CO(H)NO+ in the gas phase and leads to the conclusion that the proton-bound pairs involving (CH3)3CNO2 are a mixture of nitro-nitro and nitro-nitrite proton-bound pairs. The nitrite isomer can dissociate into protonated t-butyl nitrite and neutral nitroalkane via a simple hydrogen-bond cleavage. A more favourable competing dissociation process leads to the loss of t-butanol to form the ((CH3)3CNO2)(NO)+ complex.

  7. Relationship between intracellular ionic strength and expression of tonicity-responsive genes in rat papillary collecting duct cells.

    PubMed

    Neuhofer, Wolfgang; Bartels, Helmut; Fraek, Maria-L; Beck, Franz-X

    2002-08-15

    Intracellular ionic strength may play an important role in regulating the expression of genes encoding osmolyte-accumulating molecules. To establish whether a strict relation exists between these variables, intracellular ionic strength (sum of Na+, Cl- and K+ concentrations) and the relative abundance of mRNA derived from various tonicity-sensitive genes was examined using electron microprobe analysis and Northern blots on primary cultures of rat papillary collecting duct (PCD) cells following acute or long-term alterations in medium tonicity. Hypertonic medium (450 mosmol kg(-1)) evoked an initial rise in intracellular ionic strength (269 +/- 5 vs. 194 +/- 7 mmol (kg wet weight (wt))(-1) in isotonic controls; means +/- S.E.M.), which subsequently declined gradually, and a significantly higher abundance of bgt1 (Na+- and Cl- -dependent betaine transporter), smit (Na+/myo-inositol cotransporter), ar (aldose reductase) and osp94 (osmotic stress protein 94) mRNAs. Conversely, exposure to hypotonic medium (200 mosmol kg(-1)) for 12 h was associated with significantly reduced intracellular ionic strength (153 +/- 4 mmol (kg wet wt)(-1)) and significantly reduced the abundance of smit and ar mRNAs. PCD cells preconditioned in hypotonic medium and re-exposed to isotonic medium showed significantly higher abundance of these mRNAs than isotonic controls, although the intracellular ionic strength did not differ. Two further tonicity-sensitive genes responded differently to medium tonicity: while the abundance of hsp70 (heat shock protein 70) mRNA increased significantly following both hypo- and hypertonic stress, inos (inducible nitric oxide synthase) mRNA abundance correlated inversely with medium tonicity. These findings support the view that the effect of intracellular ionic strength on the expression of bgt1, smit, ar and osp94 is modulated by additional factors such as cell volume, and that its effect on the pathways regulating hsp70 and inos is even more complex.

  8. Relationship between intracellular ionic strength and expression of tonicity-responsive genes in rat papillary collecting duct cells

    PubMed Central

    Neuhofer, Wolfgang; Bartels, Helmut; Fraek, Maria-L; Beck, Franz-X

    2002-01-01

    Intracellular ionic strength may play an important role in regulating the expression of genes encoding osmolyte-accumulating molecules. To establish whether a strict relation exists between these variables, intracellular ionic strength (sum of Na+, Cl− and K+ concentrations) and the relative abundance of mRNA derived from various tonicity-sensitive genes was examined using electron microprobe analysis and Northern blots on primary cultures of rat papillary collecting duct (PCD) cells following acute or long-term alterations in medium tonicity. Hypertonic medium (450 mosmol kg−1) evoked an initial rise in intracellular ionic strength (269 ± 5 vs. 194 ± 7 mmol (kg wet weight (wt))−1 in isotonic controls; means ± s.e.m.), which subsequently declined gradually, and a significantly higher abundance of bgt1 (Na+- and Cl−-dependent betaine transporter), smit (Na+/myo-inositol cotransporter), ar (aldose reductase) and osp94 (osmotic stress protein 94) mRNAs. Conversely, exposure to hypotonic medium (200 mosmol kg−1) for 12 h was associated with significantly reduced intracellular ionic strength (153 ± 4 mmol (kg wet wt)−1) and significantly reduced the abundance of smit and ar mRNAs. PCD cells preconditioned in hypotonic medium and re-exposed to isotonic medium showed significantly higher abundance of these mRNAs than isotonic controls, although the intracellular ionic strength did not differ. Two further tonicity-sensitive genes responded differently to medium tonicity: while the abundance of hsp70 (heat shock protein 70) mRNA increased significantly following both hypo- and hypertonic stress, inos (inducible nitric oxide synthase) mRNA abundance correlated inversely with medium tonicity. These findings support the view that the effect of intracellular ionic strength on the expression of bgt1, smit, ar and osp94 is modulated by additional factors such as cell volume, and that its effect on the pathways regulating hsp70 and inos is even more complex. PMID

  9. Autotrophic denitrification in microbial fuel cells treating low ionic strength waters.

    PubMed

    Puig, Sebastià; Coma, Marta; Desloover, Joachim; Boon, Nico; Colprim, Jesús; Balaguer, M Dolors

    2012-02-21

    The presence of elevated concentrations of nitrates in drinking water has become a serious concern worldwide. The use of autotrophic denitrification in microbial fuel cells (MFCs) for waters with low ionic strengths (i.e., 1000 μS·cm(-1)) has not been considered previously. This study evaluated the feasibility of MFC technology for water denitification and also identified and quantified potential energy losses that result from their usage. The low conductivity (<1600 μS·cm(-1)) of water limited the nitrogen removal efficiency and power production of MFCs and led to the incomplete reduction of nitrate and the nitrous oxide (N(2)O) production (between 4 and 20% of nitrogen removed). Cathodic overpotential was identified as the main energy loss factors (83-90% of total losses). That high overpotential was influenced by denitrification intermediates (NO(2)(-) and N(2)O) and the potential used by microorganisms for growth, activation, and maintenance.

  10. Improved dye-sensitized solar cells by composite ionic liquid electrolyte incorporating layered titanium phosphate

    SciTech Connect

    Cheng, Ping; Lan, Tian; Wang, Wanjun; Wu, Haixia; Yang, Haijun; Guo, Shouwu

    2010-05-15

    We reported a composite electrolyte prepared by incorporating layered {alpha}-titanium phosphate ({alpha}-TiP) into a binary ionic liquid of 1-propyl-3-methylimidazolium iodide (PMII) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF{sub 4}) (volume ratio, 13:7) electrolyte. The addition of {alpha}-TiP markedly improved the photovoltaic properties of dye-sensitized solar cells (DSSCs) compared to that without {alpha}-TiP. The enhancement was explained by improved diffusion of tri-iodide (I{sub 3}{sup -}) ions, suppressed electron recombination with I{sub 3}{sup -} in the electrolyte and increased lifetime of electrons in mesoscopic TiO{sub 2} film. (author)

  11. Multiple effects of nordihydroguaiaretic acid on ionic currents in rat isolated type I carotid body cells

    PubMed Central

    Hatton, C J; Peers, C

    1997-01-01

    The effects of the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) on the ionic currents of rat carotid body type I cells were investigated by use of whole-cell and outside-out patch clamp techniques. NDGA (5–50 μM) produced a concentration-dependent inhibition of whole-cell K+ currents at all activating test potentials (holding potential −70 mV). The time-course of the inhibition was also concentration-dependent and the effects of NDGA were only reversible following brief periods of exposure (<2 min). Another lipoxygenase inhibitor, phenidone (5 μM), was without effect on whole-cell K+ currents in carotid body type I cells. NDGA (5–50 μM) also inhibited whole-cell Ca2+ channel currents (recorded with Ba2+ as charge carrier) in a concentration-dependent manner. Isolation of voltage-gated K+ channels by use of high [Mg2+] (6 mM), low [Ca2+] (0.1 mM) solutions revealed a direct inhibition of the voltage-sensitive component of the whole-cell K+ current by NDGA (50 μM). In excised, outside-out patches NDGA (20–50 μM) increased large conductance, Ca2+ activated K+ channel activity approximately 10 fold, an effect which could be reversed by either tetraethylammonium (10 mM) or charybdotoxin (30 nM). It is concluded that NDGA activates maxi-K+ channels in carotid body type I cells and over the same concentration range inhibits voltage-sensitive K+ and Ca2+ channels. The inhibition of whole cell K+ currents seen is most likely due to a combination of direct inhibition of the voltage-sensitive K+ current and indirect inhibition of maxi-K+ channel activity through blockade of Ca2+ channels. PMID:9384510

  12. Muscle-Bound Primordial Stem Cells Give Rise to Myofiber-Associated Myogenic and Non-Myogenic Progenitors

    PubMed Central

    Chapal-Ilani, Noa; Itzkovitz, Shalev; Horovitz, Inna; Reizel, Yitzhak; Benayahu, Dafna; Shapiro, Ehud

    2011-01-01

    Myofiber cultures give rise to myogenic as well as to non-myogenic cells. Whether these myofiber-associated non-myogenic cells develop from resident stem cells that possess mesenchymal plasticity or from other stem cells such as mesenchymal stem cells (MSCs) remain unsolved. To address this question, we applied a method for reconstructing cell lineage trees from somatic mutations to MSCs and myogenic and non-myogenic cells from individual myofibers that were cultured at clonal density. Our analyses show that (i) in addition to myogenic progenitors, myofibers also harbor non-myogenic progenitors of a distinct, yet close, lineage; (ii) myofiber-associated non-myogenic and myogenic cells share the same muscle-bound primordial stem cells of a lineage distinct from bone marrow MSCs; (iii) these muscle-bound primordial stem-cells first part to individual muscles and then differentiate into myogenic and non-myogenic stem cells. PMID:22022423

  13. Water-resistant, solid-state, dye-sensitized solar cells based on hydrophobic organic ionic plastic crystal electrolytes.

    PubMed

    Li, Shichao; Qiu, Lihua; Shi, Chengzhen; Chen, Xiaojian; Yan, Feng

    2014-02-26

    Water-resistant, solid-state, dye-sensitized solar cells with excellent long-term stability at 100% relative humidity and at 50 °C are fabricated on the basis of a novel hydrophobic organic ionic plastic crystal electrolyte and hybrid redox couple. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Compartmentalization of ER-Bound Chaperone Confines Protein Deposit Formation to the Aging Yeast Cell.

    PubMed

    Saarikangas, Juha; Caudron, Fabrice; Prasad, Rupali; Moreno, David F; Bolognesi, Alessio; Aldea, Martí; Barral, Yves

    2017-03-20

    In order to produce rejuvenated daughters, dividing budding yeast cells confine aging factors, including protein aggregates, to the aging mother cell. The asymmetric inheritance of these protein deposits is mediated by organelle and cytoskeletal attachment and by cell geometry. Yet it remains unclear how deposit formation is restricted to the aging lineage. Here, we show that selective membrane anchoring and the compartmentalization of the endoplasmic reticulum (ER) membrane confine protein deposit formation to aging cells during division. Supporting the idea that the age-dependent deposit forms through coalescence of smaller aggregates, two deposits rapidly merged when placed in the same cell by cell-cell fusion. The deposits localized to the ER membrane, primarily to the nuclear envelope (NE). Strikingly, weakening the diffusion barriers that separate the ER membrane into mother and bud compartments caused premature formation of deposits in the daughter cells. Detachment of the Hsp40 protein Ydj1 from the ER membrane elicited a similar phenotype, suggesting that the diffusion barriers and farnesylated Ydj1 functioned together to confine protein deposit formation to mother cells during division. Accordingly, fluorescence correlation spectroscopy measurements in dividing cells indicated that a slow-diffusing, possibly client-bound Ydj1 fraction was asymmetrically enriched in the mother compartment. This asymmetric distribution depended on Ydj1 farnesylation and intact diffusion barriers. Taking these findings together, we propose that ER-anchored Ydj1 binds deposit precursors and prevents them from spreading into daughter cells during division by subjecting them to the ER diffusion barriers. This ensures that the coalescence of precursors into a single deposit is restricted to the aging lineage.

  15. Microtubule and Cell Contact Dependency of ER-bound PTP1B Localization in Growth Cones

    PubMed Central

    Fuentes, Federico

    2009-01-01

    PTP1B is an ER-bound protein tyrosine phosphatase implied in the regulation of cell adhesion. Here we investigated mechanisms involved in the positioning and dynamics of PTP1B in axonal growth cones and evaluated the role of this enzyme in axons. In growth cones, PTP1B consistently localizes in the central domain, and occasionally at the peripheral region and filopodia. Live imaging of GFP-PTP1B reveals dynamic excursions of fingerlike processes within the peripheral region and filopodia. PTP1B and GFP-PTP1B colocalize with ER markers and coalign with microtubules at the peripheral region and redistribute to the base of the growth cone after treatment with nocodazole, a condition that is reversible. Growth cone contact with cellular targets is accompanied by invasion of PTP1B and stable microtubules in the peripheral region aligned with the contact axis. Functional impairment of PTP1B causes retardation of axon elongation, as well as reduction of growth cone filopodia lifetime and Src activity. Our results highlight the role of microtubules and cell contacts in the positioning of ER-bound PTP1B to the peripheral region of growth cones, which may be required for the positive role of PTP1B in axon elongation, filopodia stabilization, and Src activity. PMID:19158394

  16. Highly stable ionic-covalent cross-linked sulfonated poly(ether ether ketone) for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Lei, Linfeng; Zhu, Xingye; Xu, Jianfeng; Qian, Huidong; Zou, Zhiqing; Yang, Hui

    2017-05-01

    A novel ionic cross-linked sulfonated poly(ether ether ketone) containing equal content of sulfonic acid and pendant tertiary amine groups (TA-SPEEK) has been initially synthesized for the application in direct methanol fuel cells (DMFCs). By adjusting the ratio of p-xylene dibromide to tertiary amine groups of TA-SPEEK, a series of ionic-covalent cross-linked membranes (C-SPEEK-x) with tunable degree of cross-linking are prepared. Compared with the pristine membrane, the ionic and ionic-covalent cross-linked proton exchange membranes (PEMs) exhibit reduced methanol permeability and improved mechanical properties, dimensional and oxidative stability. The proton conductivity and methanol selectivity of protonated TA-SPEEK and C-SPEEK-x at 25 °C is up to 0.109 S cm-1 and 3.88 × 105 S s cm-3, respectively, which are higher than that of Nafion 115. The DMFC incorporating C-SPEEK-25 exhibits a maximum power density as high as 35.3 mW cm-2 with 4 M MeOH at 25 °C (31.8 mW cm-2 for Nafion 115). Due to the highly oxidative stability of the membrane, no obvious performance degradation of the DMFC is observed after more than 400 h operation, indicating such cost-effective ionic-covalent cross-linked membranes have substantial potential as alternative PEMs for DMFC applications.

  17. Robust High-performance Dye-sensitized Solar Cells Based on Ionic Liquid-sulfolane Composite Electrolytes

    PubMed Central

    Lau, Genevieve P. S.; Décoppet, Jean-David; Moehl, Thomas; Zakeeruddin, Shaik M.; Grätzel, Michael; Dyson, Paul J.

    2015-01-01

    Novel ionic liquid-sulfolane composite electrolytes based on the 1,2,3-triazolium family of ionic liquids were developed for dye-sensitized solar cells. The best performing device exhibited a short-circuit current density of 13.4 mA cm−2, an open-circuit voltage of 713 mV and a fill factor of 0.65, corresponding to an overall power conversion efficiency (PCE) of 6.3%. In addition, these devices are highly stable, retaining more than 95% of the initial device PCE after 1000 hours of light- and heat-stress. These composite electrolytes show great promise for industrial application as they allow for a 14.5% improvement in PCE, compared to the solvent-free eutectic ionic liquid electrolyte system, without compromising device stability. PMID:26670595

  18. Robust High-performance Dye-sensitized Solar Cells Based on Ionic Liquid-sulfolane Composite Electrolytes

    NASA Astrophysics Data System (ADS)

    Lau, Genevieve P. S.; Décoppet, Jean-David; Moehl, Thomas; Zakeeruddin, Shaik M.; Grätzel, Michael; Dyson, Paul J.

    2015-12-01

    Novel ionic liquid-sulfolane composite electrolytes based on the 1,2,3-triazolium family of ionic liquids were developed for dye-sensitized solar cells. The best performing device exhibited a short-circuit current density of 13.4 mA cm-2, an open-circuit voltage of 713 mV and a fill factor of 0.65, corresponding to an overall power conversion efficiency (PCE) of 6.3%. In addition, these devices are highly stable, retaining more than 95% of the initial device PCE after 1000 hours of light- and heat-stress. These composite electrolytes show great promise for industrial application as they allow for a 14.5% improvement in PCE, compared to the solvent-free eutectic ionic liquid electrolyte system, without compromising device stability.

  19. Optimization of the recovery efficiency in an axial HGMF cell with bounded flow field

    NASA Astrophysics Data System (ADS)

    Badescu, V.; Murariu, V.; Rotariu, O.; Rezlescu, N.

    1996-09-01

    This work presents a method to optimize the recovery efficiency of fine paramagnetic particles from a liquid suspension in an axial HGMF cell. The cell has the flow field bounded by a circular cylindrical wall. It has only one ferromagnetic wire mounted outside the flow field, parallel with its axis and in `paramagnetic capture mode'. The optimization criterion was deduced from the analysis of the particles' trajectories inside the magnetic active space. It is based on the relationship between the geometrical 0022-3727/29/9/042/img1 and operational 0022-3727/29/9/042/img2 parameters for which the filtration efficiency is 100%. The work also presents some experimental data which are in good agreement with theoretical results.

  20. Allosteric activation of membrane-bound glutamate receptors using coordination chemistry within living cells

    NASA Astrophysics Data System (ADS)

    Kiyonaka, Shigeki; Kubota, Ryou; Michibata, Yukiko; Sakakura, Masayoshi; Takahashi, Hideo; Numata, Tomohiro; Inoue, Ryuji; Yuzaki, Michisuke; Hamachi, Itaru

    2016-10-01

    The controlled activation of proteins in living cells is an important goal in protein-design research, but to introduce an artificial activation switch into membrane proteins through rational design is a significant challenge because of the structural and functional complexity of such proteins. Here we report the allosteric activation of two types of membrane-bound neurotransmitter receptors, the ion-channel type and the G-protein-coupled glutamate receptors, using coordination chemistry in living cells. The high programmability of coordination chemistry enabled two His mutations, which act as an artificial allosteric site, to be semirationally incorporated in the vicinity of the ligand-binding pockets. Binding of Pd(2,2‧-bipyridine) at the allosteric site enabled the active conformations of the glutamate receptors to be stabilized. Using this approach, we were able to activate selectively a mutant glutamate receptor in live neurons, which initiated a subsequent signal-transduction pathway.

  1. Quasi bound states in the continuum with few unit cells of photonic crystal slab

    NASA Astrophysics Data System (ADS)

    Taghizadeh, Alireza; Chung, Il-Sug

    2017-07-01

    Bound states in the continuum (BICs) in photonic crystal slabs represent the resonances with an infinite quality (Q)-factor, occurring above the light line for an infinitely periodic structure. We show that a set of BICs can turn into quasi-BICs with a very high Q-factor even for two or three unit cell structures. They are explained by a viewpoint of BICs originating from the tight-binding of individual resonances of each unit cell as in semiconductors. Combined with a reciprocal-space matching technique, the microcavities based on quasi-BICs can achieve a Q-factor as high as defect-based PhC microcavities. These results may enable the experimental studies of BICs in a compact platform as well as realizing high-Q mirrorless microcavities.

  2. Quantifying the total ionic release from nanoparticles after particle-cell contact.

    PubMed

    He, Xiao; Pan, Yuanyuan; Zhang, Junzhe; Li, Yuanyuan; Ma, Yuhui; Zhang, Peng; Ding, Yayun; Zhang, Jing; Wu, Zhenqiang; Zhao, Yuliang; Chai, Zhifang; Zhang, Zhiyong

    2015-01-01

    In order to assess the potential hazards of nanoparticles (NPs) releasing, better knowledge about their toxicity to microbes is required. However, it remains controversial whether NPs could exert particles pecifictoxicity. In this study, the toxic impacts of four kinds of rare earth oxides (REO) NPs (La(2)O(3),CeO(2), Gd(2)O(3), and Yb(2)O(3)) on gram-negative Escherichia coli (E. coli) pBR322 were examined. The results indicate that all the tested NPs possessed cytotoxicity against E. coli. To evaluate the ion-related toxicity of REO NPs, the NPs dissolution in the presence of test organisms was quantitatively measured using X-ray absorption fine structure (XAFS) spectroscopy. Our results suggest that NPs-cell contact could facilitate the dissolution of NPs, and the additional ionic release at the particle-cell interface might result in a substantial increase in the ion-related toxicities towards the test organisms. Therefore, the ion-related toxicity of NPs might be grossly underestimated if the additional dissolution of NPs caused by particle-cell contact was overlooked, further leading to a false interpretation of particle-specific toxicity. To the best of our knowledge, this is the first determination of the total NPs dissolution after particle-cell contact. These findings are helpful to advance mechanistic understanding of the toxicity exerted by dissolvable metal-based NPs.

  3. DEVELOPMENT AND SELECTION OF IONIC LIQUID ELECTROLYTES FOR HYDROXIDE CONDUCTING POLYBENZIMIDAZOLE MEMBRANES IN ALKALINE FUEL CELLS

    SciTech Connect

    Fox, E.

    2012-05-01

    Alkaline fuel cell (AFC) operation is currently limited to specialty applications such as low temperatures and pure HO due to the corrosive nature of the electrolyte and formation of carbonates. AFCs are the cheapest and potentially most efficient (approaching 70%) fuel cells. The fact that non-Pt catalysts can be used, makes them an ideal low cost alternative for power production. The anode and cathode are separated by and solid electrolyte or alkaline porous media saturated with KOH. However, CO from the atmosphere or fuel feed severely poisons the electrolyte by forming insoluble carbonates. The corrosivity of KOH (electrolyte) limits operating temperatures to no more than 80°C. This chapter examines the development of ionic liquids electrolytes that are less corrosive, have higher operating temperatures, do not chemically bond to CO and enable alternative fuels. Work is detailed on the IL selection and characterization as well as casting methods within the polybenzimidazole based solid membrane. This approach is novel as it targets the root of the problem (the electrolyte) unlike other current work in alkaline fuel cells which focus on making the fuel cell components more durable.

  4. Cell-bound lipases from Burkholderia sp. ZYB002: gene sequence analysis, expression, enzymatic characterization, and 3D structural model.

    PubMed

    Shu, Zhengyu; Lin, Hong; Shi, Shaolei; Mu, Xiangduo; Liu, Yanru; Huang, Jianzhong

    2016-05-03

    The whole-cell lipase from Burkholderia cepacia has been used as a biocatalyst in organic synthesis. However, there is no report in the literature on the component or the gene sequence of the cell-bound lipase from this species. Qualitative analysis of the cell-bound lipase would help to illuminate the regulation mechanism of gene expression and further improve the yield of the cell-bound lipase by gene engineering. Three predictive cell-bound lipases, lipA, lipC21 and lipC24, from Burkholderia sp. ZYB002 were cloned and expressed in E. coli. Both LipA and LipC24 displayed the lipase activity. LipC24 was a novel mesophilic enzyme and displayed preference for medium-chain-length acyl groups (C10-C14). The 3D structural model of LipC24 revealed the open Y-type active site. LipA displayed 96 % amino acid sequence identity with the known extracellular lipase. lipA-inactivation and lipC24-inactivation decreased the total cell-bound lipase activity of Burkholderia sp. ZYB002 by 42 % and 14 %, respectively. The cell-bound lipase activity from Burkholderia sp. ZYB002 originated from a multi-enzyme mixture with LipA as the main component. LipC24 was a novel lipase and displayed different enzymatic characteristics and structural model with LipA. Besides LipA and LipC24, other type of the cell-bound lipases (or esterases) should exist.

  5. Highly efficient solid-state dye-sensitized solar cells based on hexylimidazolium iodide ionic polymer electrolyte prepared by in situ low-temperature polymerization

    NASA Astrophysics Data System (ADS)

    Wang, Guiqiang; Yan, Chao; Zhang, Juan; Hou, Shuo; Zhang, Wei

    2017-03-01

    Solid-state dye-sensitized solar cells (DSCs) are fabricated using a novel ionic polymer electrolyte containing hexylimidazolium iodide (HII) ionic polymer prepared by in situ polymerization of N,N‧-bis(imidazolyl) hexane and 1,6-diiodohexane without an initiator at low temperature (40 °C). The as-prepared HII ionic polymer has a similar structure to alkylimidazolium iodide ionic liquid, and the imidazolium cations are contained in the polymer main chain; so, it can act simultaneously as the redox mediator in the electrolyte. By incorporating an appropriate amount of 1,3-dimethylimidazolium iodide (DMII) in HII ionic polymer (DMII/HII ionic polymer = 0.7:1, weight ratio), the conductivity of the ionic polymer electrolyte is greatly improved due to the formation of Grotthuss bond exchange. In addition, in situ synthesis of ionic polymer electrolyte guarantees a good pore-filling of the electrolyte in the TiO2 photoanode. As a result, the solid-state DSC based on the ionic polymer electrolyte containing HII ionic polymer and DMII without iodine achieves a conversion efficiency of 6.55% under the illumination of 100 mW cm-2 (AM 1.5), which also exhibits a good at-rest stability at room temperature.

  6. Expression of membrane-bound burst-promoting activity is mediated by allogeneic effector cells.

    PubMed

    Guha, A; Tuck, D; Sorba, S; Dainiak, N

    1993-09-01

    To investigate whether "self" and "non-self" recognition processes are involved in murine erythropoiesis, the expression of membrane-bound burst-promoting activity (mBPA) was determined for B lymphocytes purified from spleens of CF-1, C57 BL/6J, B6021-7115, and CAF-1J mice using syngeneic and allogeneic bone marrow cultures. Addition of B lymphocyte conditioned medium (LCM), shed membrane-derived vesicles, or intact plasma membranes prepared from syngeneic murine cells stimulated erythroid burst-forming unit (BFU-E) proliferation by two- to three-fold above control levels. BFU-E proliferation was increased by six- to eight-fold, however, when LCM, shed membrane vesicles, or plasma membranes purified from allogenic B lymphocytes were used as sources of growth-stimulatory activity. Bioactivity was immunoprecipitated from detergent extracts of membranes purified from both allogeneic and syngeneic lymphocytes with a monoclonal antibody that specifically recognizes mBPA, suggesting that the factors expressed by these cells share antigenic determinants. The results indicate that allogeneic effector cells are a more potent source of mBPA-like molecules than are syngeneic cells, suggesting that immune mechanisms may be involved in inducing erythroid growth factor expression at the B cell surface.

  7. Entry Kinetics and Cell-Cell Transmission of Surface-Bound Retroviral Vector Particles

    PubMed Central

    O’Neill, Lee S.; Skinner, Amy M.; Woodward, Josha A.; Kurre, Peter

    2010-01-01

    Background Transduction with recombinant Human Immunodeficiency Virus (HIV) -1 derived lentivirus vectors is a multi-step process initiated by surface attachment and subsequent receptor-directed uptake into the target cell. We previously reported the retention of vesicular stomatitis virus G protein (VSV-G) pseudotyped particles on murine progenitor cells and their delayed cell-cell transfer. Methods To examine the underlying mechanism in more detail we used a combination of approaches focused on investigating the role of receptor-independent factors in modulating attachment. Results Studies of synchronized transduction herein reveal cell-type specific rates of vector particle clearance with substantial delays during particle entry into murine hematopoietic progenitor cells. The observed uptake kinetics from the surface of the 1° cell correlate inversely with the magnitude of transfer to 2° targets, corresponding with our initial observation of preferential cell-cell transfer in the context of brief vector exposures. We further demonstrate that vector particle entry into cells is associated with the cell–type specific abundance of extracellular matrix fibronectin. Residual particle – ECM binding and 2° transfer can be competitively disrupted by heparin exposure without affecting murine progenitor homing and repopulation. Conclusions While cellular attachment factors, including fibronectin, aid gene transfer by colocalizing particles to cells and disfavoring early dissociation from targets, they also appear to stabilize particles on the cell surface. Our study highlights the inadvertent consequences for cell entry and cell-cell transfer. PMID:20440757

  8. Parasitic Currents Caused by Different Ionic and Electronic Conductivities in Fuel Cell Anodes.

    PubMed

    Schalenbach, Maximilian; Zillgitt, Marcel; Maier, Wiebke; Stolten, Detlef

    2015-07-29

    The electrodes in fuel cells simultaneously realize electric and ionic conductivity. In the case of acidic polymer electrolytes, the electrodes are typically made of composites of carbon-supported catalyst and Nafion polymer electrolyte binder. In this study, the interaction of the proton conduction, the electron conduction, and the electrochemical hydrogen conversion in such composite electrode materials was examined. Exposed to a hydrogen atmosphere, these composites displayed up to 10-fold smaller resistivities for the proton conduction than that of Nafion membranes. This effect was ascribed to the simultaneously occurring electrochemical hydrogen oxidation and evolution inside the composite samples, which are driven by different proton and electron resistivities. The parasitic electrochemical currents resulting were postulated to occur in the anode of fuel cells with polymer, solid oxide, or liquid alkaline electrolytes, when the ohmic drop of the ion conduction in the anode is higher with the anodic kinetic overvoltage (as illustrated in the graphical abstract). In this case, the parasitic electrochemical currents increase the anodic kinetic overpotential and the ohmic drop in the anode. Thinner fuel cell anodes with smaller ohmic drops for the ion conduction may reduce the parasitic electrochemical currents.

  9. Studies on the Ionic Permeability of Muscle Cells and their Models

    PubMed Central

    Ling, Gilbert N.; Ochsenfeld, Margaret M.

    1965-01-01

    We studied the effect an alkali-metal ion exercised on the rate of entry of another alkali-metal ion into frog sartorius muscle cells and their models (i.e., ion exchange resin and sheep's wool). In the case of frog muscle, it was shown that the interaction fell into one of four categories; competition, facilitation, and two types of indifference. The observed pK value (4.6 to 4.7) of the surface anionic groups that combine with the alkali-metal ions suggests that they are β- or γ-carboxyl groups of proteins on the cell surface. The results were compared with four theoretical models which included three membrane models (continuous lipoid membrane with carrier; leaky membrane with carrier; membrane with fixed ionic sites) and one bulk-phase model. This comparison led to the conclusion that the only model that is self-consistent and agrees with all of the experimental facts is the one based on the concept that the entire living cell represents a proteinaceous fixed-charge system; this model correctly predicts all four types of interaction observed. PMID:5884012

  10. ATP crossing the cell plasma membrane generates an ionic current in xenopus oocytes.

    PubMed

    Bodas, E; Aleu, J; Pujol, G; Martin-Satué, M; Marsal, J; Solsona, C

    2000-07-07

    The presence of ATP within cells is well established. However, ATP also operates as an intercellular signal via specific purinoceptors. Furthermore, nonsecretory cells can release ATP under certain experimental conditions. To measure ATP release and membrane currents from a single cell simultaneously, we used Xenopus oocytes. We simultaneously recorded membrane currents and luminescence. Here, we show that ATP release can be triggered in Xenopus oocytes by hyperpolarizing pulses. ATP release (3.2 +/- 0.3 pmol/oocyte) generated a slow inward current (2.3 +/- 0.1 microA). During hyperpolarizing pulses, the permeability for ATP(4-) was more than 4000 times higher than that for Cl(-). The sensitivity to GdCl(3) (0. 2 mm) of hyperpolarization-induced ionic current, ATP release and E-ATPase activity suggests their dependence on stretch-activated ion channels. The pharmacological profile of the current inhibition coincides with the inhibition of ecto-ATPase activity. This enzyme is highly conserved among species, and in humans, it has been cloned and characterized as CD39. The translation, in Xenopus oocytes, of human CD39 mRNA encoding enhances the ATP-supported current, indicating that CD39 is directly or indirectly responsible for the electrodiffusion of ATP.

  11. [The Influence of Different Ionic Concentration in Cell Physiological Solution on Temperature Measurement by Near Infrared].

    PubMed

    Zheng, Yu; Chen, Xiong; Zhou, Mei; Wang, Meng-jun; Wang, Jin-hai; Li, Gang; Cui, Jun

    2015-10-01

    It is important to real-timely monitor and control the temperature of cell physiological solution in patch clamp experiments, which can eliminate the uncertainty due to temperature and improve the measurement accuracy. This paper studies the influence of different ions at different concentrations in the physiological solution on precision of a temperature model by using near infrared spectroscopy and chemometrics method. Firstly, we prepared twelve sample solutions respectively with the solutes of CaCl2, KCl and NaCl at four kinds of concentrations, and collected the spectra of different solutions at the setting temperature range 20-40 degrees C, the range of the spectra is 9 615-5 714 cm(-1). Then we divided the spectra of each solution at different temperatures into two parts (a training set and a prediction set) by three methods. Interval partial least squares method was used to select an effective wavelength range and develop calibration models between the spectra in the selected range and temperature velues. The experimental results show that RMSEP of CaCl2 solution with 0.25 g x mL(-1) is maximum, the result of the three tests are 0.386 3, 0.303 7 and 0.337 2 degrees C, RMSEP of NaCl with 0.005 g x mL(-1) solution is minimum, the result of the three tests are 0.220 8, 0.155 3 and 0.145 2 degrees C. The experimental results indicate that Ca2+ has the greatest influence on the accuracy of the temperature model of the cell physiological solution, then K+, and Na+ has the least influence. And with the ionic concentration increasing, the model accuracy decreases. Therefore; when we build the temperature model of cell physiological solution, it is necessary to change the proportion of the three kinds of main ions in cell physiological solution reasonably in order to correct the effects of different ionic concentrations in physiological solution and improve the accuracy of temperature measurements by near infrared spectroscopy.

  12. Ionic mechanisms mediating oscillatory membrane potentials in wide-field retinal amacrine cells.

    PubMed

    Vigh, Jozsef; Solessio, Eduardo; Morgans, Catherine W; Lasater, Eric M

    2003-07-01

    Particular types of amacrine cells of the vertebrate retina show oscillatory membrane potentials (OMPs) in response to light stimulation. Historically it has been thought the oscillations arose as a result of circuit properties. In a previous study we found that in some amacrine cells, the ability to oscillate was an intrinsic property of the cell. Here we characterized the ionic mechanisms responsible for the oscillations in wide-field amacrine cells (WFACs) in an effort to better understand the functional properties of the cell. The OMPs were found to be calcium (Ca2+) dependent; blocking voltage-gated Ca2+ channels eliminated the oscillations, whereas elevating extracellular Ca2+ enhanced them. Strong intracellular Ca2+ buffering (10 mM EGTA or bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid) eliminated any attenuation in the OMPs as well as a Ca2+-dependent inactivation of the voltage-gated Ca2+ channels. Pharmacological and immunohistochemical characterization revealed that WFACs express L- and N-type voltage-sensitive Ca2+ channels. Block of the L-type channels eliminated the OMPs, but omega-conotoxin GVIA did not, suggesting a different function for the N-type channels. The L-type channels in WFACs are functionally coupled to a set of calcium-dependent potassium (K(Ca)) channels to mediate OMPs. The initiation of OMPs depended on penitrem-A-sensitive (BK) K(Ca) channels, whereas their duration is under apamin-sensitive (SK) K(Ca) channel control. The Ca2+ current is essential to evoke the OMPs and triggering the K(Ca) currents, which here act as resonant currents, enhances the resonance as an amplifying current, influences the filtering characteristics of the cell membrane, and attenuates the OMPs via CDI of the L-type Ca2+ channel.

  13. Carbon Ionic Conductors for use in Novel Carbon-Ion Fuel Cells

    SciTech Connect

    Franklin H. Cocks; W. Neal Simmons; Paul A. Klenk

    2005-11-01

    Carbon-consuming fuel cells have many potential advantages, including increased efficiency and reduced pollution in power generation from coal. A large amount of work has already been done on coal fuel cells that utilize yttria-stabilized zirconium carbide as an oxygen-ion superionic membrane material. But high-temperature fuel cells utilizing yttria-stabilized zirconium require partial combustion of coal to carbon monoxide before final oxidation to carbon dioxide occurs via utilization of the oxygen- ion zirconia membrane. A carbon-ion superionic membrane material would enable an entirely new class of carbon fuel cell to be developed, one that would use coal directly as the fuel source, without any intervening combustion process. However, a superionic membrane material for carbon ions has not yet been found. Because no partial combustion of coal would be required, a carbon-ion superionic conductor would allow the direct conversion of coal to electricity and pure CO{sub 2} without the formation of gaseous pollutants. The objective of this research was to investigate ionic lanthanide carbides, which have an unusually high carbon-bond ionicity as potential superionic carbide-ion conductors. A first step in this process is the stabilization of these carbides in the cubic structure, and this stabilization has been achieved via the preparation of pseudobinary lanthanide carbides. The diffusion rates of carbon have been measured in these carbides as stabilized to preserve the high temperature cubic structure down to room temperature. To prepare these new compounds and measure these diffusion rates, a novel, oxide-based preparation method and a new C{sup 13}/C{sup 12} diffusion technique have been developed. The carbon diffusion rates in La{sup 0.5}Er{sup 0.5}C{sub 2}, Ce{sup 0.5}Er{sup 0.5}C{sub 2}, and La{sup 0.5}Y{sup 0.5}C{sub 2}, and Ce{sup 0.5}Tm0.5C{sub 2} modified by the addition of 5 wt %Be{sub 2}C, have been determined at temperatures from 850 C to 1150 C. The

  14. Zip14 (Slc39a14) mediates non-transferrin-bound iron uptake into cells.

    PubMed

    Liuzzi, Juan P; Aydemir, Fikret; Nam, Hyeyoung; Knutson, Mitchell D; Cousins, Robert J

    2006-09-12

    Zip14 is a member of the SLC39A zinc transporter family, which is involved in zinc uptake by cells. Up-regulation of Zip14 by IL-6 appears to contribute to the hepatic zinc accumulation and hypozincemia of inflammation. At least three members of the SLC39A family transport other trace elements, such as iron and manganese, in addition to zinc. We analyzed the capability of Zip14 to mediate non-transferrin-bound iron (NTBI) uptake by overexpressing mouse Zip14 in HEK 293H cells and Sf9 insect cells. Zip14 was found to localize to the plasma membrane, and its overexpression increased the uptake of both (65)Zn and (59)Fe. Addition of bathophenanthroline sulfonate, a cell-impermeant ferrous iron chelator, inhibited Zip14-mediated iron uptake from ferric citrate, suggesting that iron is taken up by HEK cells as Fe(2+). Iron uptake by HEK and Sf9 cells expressing Zip14 was inhibited by zinc. Suppression of endogenous Zip14 expression by using Zip14 siRNA reduced the uptake of both iron and zinc by AML12 mouse hepatocytes. Zip14 siRNA treatment also decreased metallothionein mRNA levels, suggesting that compensatory mechanisms were not sufficient to restore intracellular zinc. Collectively, these results indicate that Zip14 can mediate the uptake of zinc and NTBI into cells and that it may play a role in zinc and iron metabolism in hepatocytes, where this transporter is abundantly expressed. Because NTBI is commonly found in plasma of patients with hemochromatosis and transfusional iron overload, Zip14-mediated NTBI uptake may contribute to the hepatic iron loading that characterizes these diseases.

  15. Mode of action of bradycardic agent, S 16257, on ionic currents of rabbit sinoatrial node cells.

    PubMed Central

    Bois, P.; Bescond, J.; Renaudon, B.; Lenfant, J.

    1996-01-01

    1. The effect of the bradycardic agent S 16257 on the main ionic mechanisms of diastolic depolarization in sinoatrial node cells isolated from rabbit heart, was investigated by the patch-clamp technique in whole-cell and macro-patch recordings. 2. In whole-cell conditions, S 16257 induced a marked exponential use-dependent blockade of the hyperpolarization-activated I(f) current, without shift of the voltage range of its activation curve. The rate of block increased with the drug concentration. The IC50 for the block of I(f) was 2.8 x 10(-6) M. 3. A similar use-dependent decline of I(f) was obtained with 3 microM S 16257, in cell-attached and in inside out macro-patch configurations, suggesting that the bradycardic agent interacts with I(f) channels from the inside of the cell. 4. A high concentration of S 16257 (10 microM) had no detectable effect on T-type calcium current and slightly decreased L-type calcium current (-18.12 +/- 0.66%), without significant use-dependent blockade. 5. S 16257 had no effect on the delayed outward potassium current Ik at 3 microM and slightly decreased it only at high concentrations, -16.3 +/- 1.2% at 10 microM. In contrast, zatebradine, another bradycardic agent, reduced I k by 20.3 +/- 2.5% at 3 microM. 6. In conclusion, S 16257 may lower heart rate without significant negative inotropic action. In comparison with zatebradine, S 16257 had less effect on Ik suggesting less prolongation of repolarization time. PMID:8799581

  16. Electrical and freeze-fracture analysis of the effects of ionic cadmium on cell membranes of human proximal tubule cells

    SciTech Connect

    Hazen-Martin, D.J.; Todd, J.H.; Sens, M.A.; Khan, W.; Bylander, J.E.; Smyth, B.J.; Sens, D.A. )

    1993-11-01

    The authors previously reported that cell cultures of human proximal tubule (HPT) cells respond to ionic cadmium in a manner consistent with well-defined Cd[sup 2+]-elicited responses reported for in vivo systems. However, one unique finding was that the transepithelial electrical resistance and tight junction sealing strands were altered as a result of Cd[sup 2+] exposure at micromolar concentrations. These alterations are reexamined in detail in the present report to determine whether the Cd[sup 2+]-induced alterations are specific alterations in the tight junction structure or reflect a general alteration in the cell membrane. Exhaustive analysis of tight junction sealing strands demonstrated no significant alterations due to Cd[sup 2+] exposure, even at the concentration that elicited a significant reduction in transepithelial resistance. Further analysis of intramembrane particle distribution demonstrated a significant increase in apical intramembrane particles, indicating that Cd[sup 2+] exposure altered the characteristics of the apical cell membrane. Overall, the results were consistent with evidence of Cd[sup 2+]-induced alteration in the apical cell membrane of the HPT cell.

  17. Electrical and freeze-fracture analysis of the effects of ionic cadmium on cell membranes of human proximal tubule cells.

    PubMed Central

    Hazen-Martin, D J; Todd, J H; Sens, M A; Khan, W; Bylander, J E; Smyth, B J; Sens, D A

    1993-01-01

    We previously reported that cell cultures of human proximal tubule (HPT) cells respond to ionic cadmium in a manner consistent with well-defined Cd(2+)-elicited responses reported for in vivo systems. However, one unique finding was that the transepithelial electrical resistance and tight junction sealing strands were altered as a result of Cd2+ exposure at micromolar concentrations. These alterations are reexamined in detail in the present report to determine whether the Cd(2+)-induced alterations are specific alterations in the tight junction structure or reflect a general alteration in the cell membrane. Exhaustive analysis of tight junction sealing strands demonstrated no significant alterations due to Cd2+ exposure, even at the concentration that elicited a significant reduction in transepithelial resistance. Further analysis of intramembrane particle distribution demonstrated a significant increase in apical intramembrane particles, indicating that Cd2+ exposure altered the characteristics of the apical cell membrane. Overall, the results were consistent with evidence of Cd(2+)-induced alteration in the apical cell membrane of the HPT cell. Images Figure 1. Figure 2. Figure 3. a Figure 3. b Figure 3. c Figure 3. d Figure 4. Figure 5. PMID:8137780

  18. Can Cell Bound Complement Activation Products Predict Inherited Complement Deficiency in Systemic Lupus Erythematosus?

    PubMed Central

    Waters, Barry

    2016-01-01

    Activation of the classical pathway complement system has long been implicated in stimulating immune complex mediated tissue destruction in systemic lupus erythematosus (SLE). C3 and C4 complement levels are utilized as part of SLE diagnosis and monitoring criteria. Recently, cell bound complement activation products (CBCAPs) have shown increased sensitivity in diagnosing and monitoring lupus activity, compared to traditional markers. CBCAPs are increasingly utilized in rheumatology practice as additional serological markers in evaluating SLE patients. We report a case of a patient diagnosed with SLE that had chronically low C3 and C4, along with negative CBCAPs. We surmise that the patient has an inherited complement deficiency as the etiology of her SLE and that CBCAPs could be used to predict such deficiency. PMID:28074166

  19. Boosting performance of low temperature fuel cell catalysts by subtle ionic liquid modification.

    PubMed

    Zhang, Gui-Rong; Munoz, Macarena; Etzold, Bastian J M

    2015-02-18

    High cost and poor stability of the oxygen reduction reaction (ORR) electrocatalysts are the major barriers for broad-based application of polymer electrolyte membrane fuel cells. Here we report a facile and scalable approach to improve Pt/C catalysts for ORR, by modification with small amounts of hydrophobic ionic liquid (IL). The ORR performance of these IL-modified catalysts can be readily manipulated by varying the degree of IL filling, leading to a 3.4 times increase in activity. Besides, the IL-modified catalysts exhibit substantially enhanced stability relative to Pt/C. The enhanced performance is attributed to the optimized microenvironment at the interface of Pt and electrolyte, where advantages stemming from an increased number of free sites, higher oxygen concentration in the IL and electrostatic stabilization of the nanoparticles develop fully, at the same time that the drawback of mass transfer limitation remains suppressed. These findings open a new avenue for catalyst optimization for next-generation fuel cells.

  20. Differential responses of cell wall bound phenolic compounds in sensitive and tolerant varieties of rice in response to salinity.

    PubMed

    Gupta, Poulami; De, Bratati

    2017-09-14

    In plants, cell wall bound phenolics change in response to stress. The aim of the study was to investigate the effect of NaCl induced stress on wall bound phenolics in four rice varieties, of which two (Bhutnath, Nonabokra) were salt tolerant and two (MTU 7029, Sujala) were salt sensitive. After germination, seedlings were grown in hydroponic solution and subjected to salinity stress (25mM, 50mM, 100mM and 150mM NaCl) on day 12. Wall bound phenolic compounds were determined by GC-MS based metabolite analysis. Total seven wall bound phenols were identified from the leaf tissues and eight from the root tissues. Ferulic acid and 4-hydroxycinnamic acid were found in all the four varieties. After NaCl treatment, these two wall bound phenols increased in tolerant varieties only. Significant inverse correlation between leaf length and leaf fresh weight with wall bound ferulic acid and 4-hydroxycinnamic acid in Nonabokra suggests the positive role of these wall bound phenolics in salt tolerance.

  1. Hydrogels with Modulated Ionic Load for Mammalian Cell Harvesting with Reduced Bacterial Adhesion.

    PubMed

    Gallardo, Alberto; Martínez-Campos, Enrique; García, Carolina; Cortajarena, Aitziber L; Rodríguez-Hernández, Juan

    2017-05-08

    In this manuscript, we describe the fabrication of hydrogel supports for mammalian cell handling that can simultaneously prevent materials from microbial contamination and therefore allow storage in aqueous media. For that purpose, hydrogels based on the antifouling polymer polyvinylpyrrolidone (PVP) were functionalized with different ionic groups (anionic, cationic, or two types of zwitterions). In order to prevent bacterial adhesion in the long-term, we took advantage of the synergistic effect of inherently antifouling PVP and additional antifouling moieties incorporated within the hydrogel structure. We evaluated, in a separated series of experiments, both the capability of the materials to act as supports for the growth of mammalian cell monolayers for transplantation (using C-166-GFP endothelial cell line), as well their antifouling properties against Staphylococcus aureus, were studied. All of the hydrogels are structurally pseudodouble networks with high swelling (around 90%) and similar mechanical properties (in the low range for hydrogel materials with Young modulus below 1250 kPa). With some differences, all the charged hydrogels were capable of hosting mouse endothelial cell line C166-GFP to confluence, as well as a monolayer detachment and transplantation through simple mechanical agitation. On the contrary, the uncharged hydrogel was not capable to detach a full monolayer for transplantation. Bacterial adhesion and proliferation was highly sensitive to the functionality (type of charge and density). In particular, we evidenced that monomers bearing zwitterionic sulfobetaine groups, those negatively charged as well as "electro neutral" hydrogels fabricated from stoichiometric amounts of positive and negative units, exhibit excellent antifouling properties both at initial adhesion times and during longer periods up to 72 h.

  2. Carbon ionic diffusion in mixed lanthanide dicarbides for use in novel carbon-ion fuel cells

    NASA Astrophysics Data System (ADS)

    Simmons, Walker Neal

    2001-07-01

    Solid ionic electrolytes are a major concern in fuel cell development, but only a few compounds are known to be superionic. The fluorite structure, in particular, has been the basis for several superionic conductors of F -, I-, and O2- ions. Rare earth carbides of the form LnC2 (where Ln refers to any element of the lanthanide series) have the fluorite structure when they are above their transition temperatures, which vary from 350°C (EuC2 ) to 1450°C (LuC2). The carbon atoms in these compounds reside as anions in tetragonal positions equivalent to the positions of the mobile ions, F- and O2- in the known superionic conductors CaF2 and Zr0.8Y0.2O 2. These cubic lanthanide carbide compounds could potentially be good ionic conductors for carbon. The discovery of a material with a high carbon ion conductivity would be a major scientific advance, opening the possibility of an entirely new class of fuel cells that could convert carbon directly to CO/CO2 and produce electric power without combustion. In order to stabilize the cubic fluorite structure to low temperatures, a mixture of two different lanthanide dicarbides must be formed. The lanthanide carbides having a stabilized fluorite structure that have been produced in this research are mixtures of La0.5Er0.5C2, Ce0.5Er0.5C2, and La0.5Y 0.5C2. Aluminum carbide, Al4C3, has also been investigated as a potential carbon ionic conductor. Although Al4C3 does not possess the fluorite crystal structure, it is of interest because the carbon atoms reside as single 4- ions rather than C22- ion pairs found in most carbides. The lanthanide dicarbides were synthesized by reacting mixtures of Ln 2O3 and amorphous 13C under vacuum at high temperatures (>1600°C), using a number of newly developed synthesis techniques. The diffusion coefficients for La0.5-Er0.5C 2 have been found to be approximately 2.0 • 10-13 cm2/sec at 850°C increasing to 1.7 • 10 -12 cm2/sec at 1150°C, which values are not in the range of superionic

  3. Dendritic cell-bound IgE functions to restrain allergic inflammation at mucosal sites

    PubMed Central

    Platzer, Barbara; Baker, Kristi; Vera, Miguel Pinilla; Singer, Kathleen; Panduro, Marisella; Lexmond, Willem S.; Turner, Devin; Vargas, Sara O.; Kinet, Jean-Pierre; Maurer, Dieter; Baron, Rebecca M.; Blumberg, Richard S.; Fiebiger, Edda

    2014-01-01

    Antigen-mediated crosslinking of Immunoglobulin E (IgE) bound to mast cells/basophils via FcεRI, the high affinity IgE Fc-receptor, is a well-known trigger of allergy. In humans, but not mice, dendritic cells (DCs) also express FcεRI that is constitutively occupied with IgE. In contrast to mast cells/basophils, the consequences of IgE/FcεRI signals for DC function remain poorly understood. We show that humanized mice that express FcεRI on DCs carry IgE like non-allergic humans and do not develop spontaneous allergies. Antigen-specific IgE/FcεRI crosslinking fails to induce maturation or production of inflammatory mediators in human DCs and FcεRI-humanized DCs. Furthermore, conferring expression of FcεRI to DCs decreases the severity of food allergy and asthma in disease-relevant models suggesting anti-inflammatory IgE/FcεRI signals. Consistent with the improved clinical parameters in vivo, antigen-specific IgE/FcεRI crosslinking on papain or LPS-stimulated DCs inhibits the production of pro-inflammatory cytokines and chemokines. Migration assays confirm that the IgE-dependent decrease in cytokine production results in diminished recruitment of mast cell progenitors; providing a mechanistic explanation for the reduced mast cell-dependent allergic phenotype observed in FcεRI-humanized mice. Our study demonstrates a novel immune regulatory function of IgE and proposes that DC-intrinsic IgE signals serve as a feedback mechanism to restrain allergic tissue inflammation. PMID:25227985

  4. Effects of polymer structure on properties of sulfonated polyimide/protic ionic liquid composite membranes for nonhumidified fuel cell applications.

    PubMed

    Yasuda, Tomohiro; Nakamura, Shin-ichiro; Honda, Yoshiyuki; Kinugawa, Kei; Lee, Seung-Yul; Watanabe, Masayoshi

    2012-03-01

    To investigate the effects of polymer structure on the properties of composite membranes including a protic ionic liquid, [dema][TfO] (diethylmethylammonium trifluoromethanesulfonate), for nonhumidified fuel cell applications, we synthesized sulfonated polyimides (SPIs) with different structures as matrix polymers, which have different magnitudes of ion-exchange capacities (IECs), different sequence distributions of ionic groups, and positions of sulfonate groups in the main chain or side chain. Despite having similar IECs, multiblock copolymer SPI and random copolymer SPI having sulfonate groups in the side chain exhibit higher ionic conductivity than random copolymer SPI having sulfonate groups in the main chain, indicating that the flexibility of sulfonic acid groups and the sequence distribution of ionic groups greatly affect the ion conduction. Atomic force microscopy observation revealed that the multiblock copolymer SPI forms more developed phase separation than the others. These results indicate that the flexibility of sulfonic acid groups and the connectivity of the ion conduction channel, which greatly depends on the sequence distribution, affect the ion conduction.

  5. Toxicity of nano- and ionic silver to embryonic stem cells: a comparative toxicogenomic study.

    PubMed

    Gao, Xiugong; Topping, Vanessa D; Keltner, Zachary; Sprando, Robert L; Yourick, Jeffrey J

    2017-04-11

    The widespread application of silver nanoparticles (AgNPs) and silver-containing products has raised public safety concerns about their adverse effects on human health and the environment. To date, in vitro toxic effects of AgNPs and ionic silver (Ag(+)) on many somatic cell types are well established. However, no studies have been conducted hitherto to evaluate their effect on cellular transcriptome in embryonic stem cells (ESCs). The present study characterized transcriptomic changes induced by 5.0 µg/ml AgNPs during spontaneous differentiation of mouse ESCs, and compared them to those induced by Ag(+) under identical conditions. After 24 h exposure, 101 differentially expressed genes (DEGs) were identified in AgNP-treated cells, whereas 400 genes responded to Ag(+). Despite the large differences in the numbers of DEGs, functional annotation and pathway analysis of the regulated genes revealed overall similarities between AgNPs and Ag(+). In both cases, most of the functions and pathways impacted fell into two major categories, embryonic development and metabolism. Nevertheless, a number of canonical pathways related to cancer were found for Ag(+) but not for AgNPs. Conversely, it was noted that several members of the heat shock protein and the metallothionein families were upregulated by AgNPs but not Ag(+), suggesting specific oxidative stress effect of AgNPs in ESCs. The effects of AgNPs on oxidative stress and downstream apoptosis were subsequently confirmed by flow cytometry analysis. Taken together, the results presented in the current study demonstrate that both AgNPs and Ag(+) caused transcriptomic changes that could potentially exert an adverse effect on development. Although transcriptomic responses to AgNPs and Ag(+) were substantially similar, AgNPs exerted specific effects on ESCs due to their nanosized particulate form.

  6. Simulation of red blood cells flowing over wall-bound cells

    NASA Astrophysics Data System (ADS)

    Isfahani, Amir H. G.; Zhao, Hong; Freund, Jonathan B.

    2009-11-01

    Inter-cellular dynamics play a critical role in the phenomenology of the microcirculation. We present a quantitative investigation of the forces exerted by red cells on protrusions on a microvessel of diameter around 12 μm, which is 1.5 times the longest dimension of a red cell at rest. This configuration serves as a model for white blood cells (leukocytes), which can bind nearly statically to the endothelial cells as part of the inflammation response. The simulation tools are based on an O(N N) boundary integral formulation. It permits the cells to both be realistically flexible and to approach to very close separation distances. The red blood cells are modeled as finite-deformation elastic membranes with strong resistance to surface dilatation and relatively small but finite resistance to bending. The no-slip condition is applied on the protrusion as well as the vessel walls. Simulation results show that these forces are significantly augmented by the particulate character of blood. For a tube hematocrit of 30% and a hemispherical protrusion with a height to tube diameter ratio of 0.4, the average forces are increased by about 50% and the local forces by more than two folds relative to forces from an effective viscosity homogenized blood. Different flow configurations are considered and analyzed.

  7. Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids.

    PubMed

    Marino, M G; Kreuer, K D

    2015-02-01

    The alkaline stability of 26 different quaternary ammonium groups (QA) is investigated for temperatures up to 160 °C and NaOH concentrations up to 10 mol L(-1) with the aim to provide a basis for the selection of functional groups for hydroxide exchange membranes in alkaline fuel cells and of ionic-liquid cations stable in basic conditions. Most QAs exhibit unexpectedly high alkaline stability with the exception of aromatic cations. β-Protons are found to be far less susceptible to nucleophilic attack than previously suggested, whereas the presence of benzyl groups, nearby hetero-atoms, or other electron-withdrawing species promote degradation reactions significantly. Cyclic QAs proved to be exceptionally stable, with the piperidine-based 6-azonia-spiro[5.5]undecane featuring the highest half-life at the chosen conditions. Absolute and relative stabilities presented herein stand in contrast to literature data, the differences being ascribed to solvent effects on degradation.

  8. Improving the carrier balance of light-emitting electrochemical cells based on ionic transition metal complexes.

    PubMed

    Su, Hai-Ching; Hsu, Jia-Hong

    2015-05-14

    Recently, solid-state light-emitting electrochemical cells (LECs) based on ionic transition metal complexes (iTMCs) have attracted much research interest since they have the advantages of a simple device structure, a low operation voltage and compatibility with air-stable electrodes. These properties enable LECs to be cost-effective, versatile and power-efficient organic light-emitting sources. However, it is generally not easy to modify the molecular structure to achieve balanced carrier mobilities without altering the photoluminescence quantum yield of the iTMC. Furthermore, the carrier balance and the consequent device efficiency of single-layered LECs would not be easy to optimize since no carrier injection and transport layers can be used. In this perspective, some reported techniques to improve carrier balance of LECs based on iTMCs are described and reviewed. The importance and impact of these studies are highlighted. The effects on device lifetime and turn-on time because of employing these techniques to improve the carrier balance are also discussed. This perspective concludes that even with electrochemically doped layers, improving the carrier balance of LECs would be required for realizing efficient electroluminescent emission from simple-structure organic light-emitting sources.

  9. Air supply using an ionic wind generator in a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Kwon, Kilsung; Li, Longnan; Park, Byung Ho; Lee, Seung Jun; Kim, Daejoong

    2015-06-01

    A new air supply is demonstrated for a portable polymer electrolyte membrane fuel cell (PEMFC). The air supply is an ionic wind generator (IWG) with a needle-to-cylinder configuration. The IWG supplies air to the portable PEMFC owing to momentum transfer to the air by charged molecules generated by the corona discharge from a high applied potential. There is no difference in the performance of the PEMFC when compressed air and the IWG are used as the air supply. For the varying interelectrode distance, IWG performance is varied and measured in terms of the flow rate and current. At the interelectrode distance of 9.0 mm, the air flow rate is a suitable for the portable PEMFC with low power consumption. When the IWG is used to supply air to the portable PEMFC, it is found that the flow rate per unit power consumed decreases with the applied voltage, the gross power generation monotonously increases with the applied voltage, and the highest net power (268 mW) is obtained at the applied voltage of 8.5 kV. The parasitic power ratio reaches a minimum value of ∼0.06 with the applied IWG voltage of 5.5 kV.

  10. High-temperature solid-state dye-sensitized solar cells based on organic ionic plastic crystal electrolytes.

    PubMed

    Li, Qing; Zhao, Jie; Sun, Baoquan; Lin, Bencai; Qiu, Lihua; Zhang, Yueguang; Chen, Xiaojian; Lu, Jianmei; Yan, Feng

    2012-02-14

    Organic ionic plastic crystal, 1-ethyl-1-methyl pyrrolidinium iodide (P(12) I), is employed as the solid-state electrolytes for dye-sensitized solar cells. The fabricated solid-state devices show an overall power conversion efficiency of ~5.8% under AM 1.5 radiation (50 mW/cm(2) ) and excellent long-term stability at 80 °C.

  11. Determination of the non-ionic detergent insolubility and phosphoprotein associations of glycosylphosphatidylinositol-anchored proteins expressed on T cells.

    PubMed Central

    Solomon, K R; Mallory, M A; Finberg, R W

    1998-01-01

    Glycosylphosphatidylinositol (GPI)-anchored proteins are poorly solublized in non-ionic detergents such as Triton X-100 and Nonidet P40, but are easily solublized by detergents with high critical micelle concentrations such as octylglucoside. This solubility profile has been suggested to be due to the localization of GPI-anchored proteins to lipid microdomains rich in cholesterol and sphingolipids. Additionally, GPI-anchored proteins expressed on haemopoietic cells have been shown to associate with src-family tyrosine kinases and heterotrimeric G proteins. Despite these observations, the non-ionic detergent insolubility of GPI-anchored proteins on haemopoietic cells has not been quantified nor has a relationship between the non-ionic detergent insolubility of these proteins and their association with signal-transduction molecules been identified. Here we show that GPI-anchored proteins found on T-cell tumours and activated T cells, although significantly more insoluble then transmembrane proteins, are not uniform in their detergent insolubility. Whereas CD59 was between 4% and 13% soluble, CD48 was between 13% and 25% soluble, CD55 was between 20% and 30% soluble, and CD109 was between 34% and 75% soluble. The ability of these GPI-anchored proteins to associate with phosphoproteins was correlated with their detergent insolubility: the more detergent-insoluble that a GPI-anchored protein was, the greater the level of phosphoprotein associations. These experiments reveal a relationship between non-ionic detergent insolubility and association with signal-transduction molecules and suggest a cause-and-effect relationship between these two properties. In total, these experiments support the hypothesis that the association of GPI-anchored proteins with signalling molecules is due to their sorting to lipid microdomains. PMID:9716490

  12. Determination of the non-ionic detergent insolubility and phosphoprotein associations of glycosylphosphatidylinositol-anchored proteins expressed on T cells.

    PubMed

    Solomon, K R; Mallory, M A; Finberg, R W

    1998-09-01

    Glycosylphosphatidylinositol (GPI)-anchored proteins are poorly solublized in non-ionic detergents such as Triton X-100 and Nonidet P40, but are easily solublized by detergents with high critical micelle concentrations such as octylglucoside. This solubility profile has been suggested to be due to the localization of GPI-anchored proteins to lipid microdomains rich in cholesterol and sphingolipids. Additionally, GPI-anchored proteins expressed on haemopoietic cells have been shown to associate with src-family tyrosine kinases and heterotrimeric G proteins. Despite these observations, the non-ionic detergent insolubility of GPI-anchored proteins on haemopoietic cells has not been quantified nor has a relationship between the non-ionic detergent insolubility of these proteins and their association with signal-transduction molecules been identified. Here we show that GPI-anchored proteins found on T-cell tumours and activated T cells, although significantly more insoluble then transmembrane proteins, are not uniform in their detergent insolubility. Whereas CD59 was between 4% and 13% soluble, CD48 was between 13% and 25% soluble, CD55 was between 20% and 30% soluble, and CD109 was between 34% and 75% soluble. The ability of these GPI-anchored proteins to associate with phosphoproteins was correlated with their detergent insolubility: the more detergent-insoluble that a GPI-anchored protein was, the greater the level of phosphoprotein associations. These experiments reveal a relationship between non-ionic detergent insolubility and association with signal-transduction molecules and suggest a cause-and-effect relationship between these two properties. In total, these experiments support the hypothesis that the association of GPI-anchored proteins with signalling molecules is due to their sorting to lipid microdomains.

  13. Deformation of a single red blood cell in bounded Poiseuille flows.

    PubMed

    Shi, Lingling; Pan, Tsorng-Whay; Glowinski, Roland

    2012-01-01

    Deformation of a red blood cell (RBC) in bounded two-dimensional Poiseuille flows is studied by using an immersed boundary method (IBM). An elastic spring model is applied to simulate the skeleton structure of a RBC membrane. As a benchmarking test, the dynamical behavior of a single RBC under a simple shear flow has been validated. Then we focus on investigating the motion and the deformation of a single RBC in Poiseuille flows by varying the swelling ratio (s*), the initial angle of the long axis of the cell at the centerline (ϕ), the maximum velocity at the centerline of fluid flow (umax), the membrane bending stiffness of a RBC (kb), and the height of the microchannel (H). Two motions of oscillation and vacillating breathing (swing) of a RBC are observed in both narrow and wide channels. The strength of the vacillating-breathing motion depends on the degree of confinement and the value of umax. A RBC exhibits a strong vacillating-breathing motion as the degree of confinement is larger or the value of umax is higher. For the same degree of confinement, the vacillating-breathing motion appears to be relatively weaker but persists longer as the value of umax is lower. The continuation of shape change from the slippery to the parachute by varying the value of umax is obtained for the biconcave shape cell in a narrower channel. In particular, parachute shape and bulletlike shape, depending on the angle ϕ, coexist for the elliptic shape cell given initially with lower umax in a narrower channel.

  14. Behaviour of water bound in bone marrow cells affected by organic solvents of different polarity.

    PubMed

    Turov, Vladimir V; Kerus, Sergey V; Gun'ko, Vladimir M

    2009-08-01

    The behaviour of intracellular water affected by organic solvents of different polarity in partially dehydrated marrow cells obtained from tubular bones of broiler chickens was studied using (1)H NMR spectroscopy at 210-290K. The (1)H NMR spectra of intracellular water include two signals which can be assigned to strongly (SAW, chemical shift of the proton resonance delta(H)=4-5ppm) and weakly (WAW, delta(H)=1.2-1.7ppm) associated waters which can be also divided into weakly (WBW, frozen at 250-0.8kJ/mol) and strongly (SBW, unfrozen at T<250K, DeltaG<-0.8kJ/mol) bound intracellular waters. Solvents of different polarity such as dimethylsulfoxide-d(6) (Me(2)SO-d(6)), acetonitrile-d(3), and chloroform-d differently affect structure, Gibbs free energy, and molecular mobility of intracellular water. A maximal fraction of SBW in WAW and a minimal fraction of SBW in SAW are observed on absorption of acetonitrile (0.8g/g) by cells. The opposite results are on addition of Me(2)SO (0.8g/g) which strongly changes organisation of intracellular water and enhances the freezing point depression of SBW.

  15. Bathophenanthrolene disulfonic acid and sodium dithionite effectively remove surface-bound iron from Caco-2 cell monolayers.

    PubMed

    Glahn, R P; Gangloff, M B; Van Campen, D R; Miller, D D; Wien, E M; Norvell, W A

    1995-07-01

    Iron uptake by Caco-2 cell monolayers is commonly assessed by incubating the cells under radiolabeled iron solutions, removing the radiolabeled solution, rinsing to stop uptake and measuring the radioactivity retained by the cells. It is therefore essential to differentiate between iron that is nonspecifically bound to the cell surface from that which has been taken up by the cell. We report here on a method for removal of surface-bound iron from Caco-2 cell monolayers. We used a 140 mmol/L NaCl, 10 mmol/L PIPES, pH 6.7 solution containing 5.0 mmol/L sodium dithionite (Na2S2O4) and 5.0 mmol/L bathophenanthroline disulfonic acid to reduce, remove and chelate iron bound to the cell surface. We validated our method by demonstrating the removal of 97% of an insoluble iron complex from the apical surface of Caco-2 cell monolayers. Our data indicate that the removal solution does not damage the apical membrane and thereby does not have access to intracellular iron; thus only surface bound iron is removed. The remaining cell-associated iron represents that which has been transported into the cell. We present data on the uptake and nonspecific binding of iron from iron complexes of both ferrous and ferric forms, and show that iron removal treatment resulted in uptake measurements that agree more closely with accepted principles of iron uptake by intestinal epithelium. The iron removal method used in this study should provide investigators with a valuable tool for accurately determining iron uptake by epithelial cells in culture.

  16. Conductive polymer as a controlled microenvironment for the potentiometric high-throughput evaluation of ionic liquid cell toxicity.

    PubMed

    Qiu, Weilian; Zeng, Xiangqun

    2008-09-01

    This paper presents both biological and potentiometric evaluations of the cell toxicity of a widely used ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF(4)), to Chinese hamster lung fibroblast cells (V79 cell line). The innovative potentiometric study takes advantage of the unique properties of conductive polymer polypyrrole (PPY) for the potentiometric evaluation of cell toxicity of [bmim]BF(4) to the V79 cells in a real-time, noninvasive and high-throughput manner. The conductive polymer PPY provides a controlled microenvironment that allows the quantitative release of the anions of the ionic liquids into the cells being monitored in real time and noninvasively. Parallel biological assay results showed that V79 cells exposed to [bmim]BF(4) usually grew in clusters, and that many small vacuoles could be seen in the cytoplasm. At the 24th hour after the V79 cells had been exposed to the ionic liquid (IL), the half inhibition concentration (EC(50)) of [bmim]BF(4) was around 5 mM. From a cell cycle study performed using a FACScan flow cytometer, it was found that the V79 cells could be partially locked to the G(1) phase by [bmim]BF(4), which extended the doubling time for cell growth. Comparing with the EC(50) values of cadmium chloride and mercury chloride, [bmim]BF(4) is not very toxic, but it may have a long-term toxic effect on mammalian cells. Compared to traditional biological in vitro assays, the use of a conductive polymer substrate in combination with a potentiometric sensor array is much more sensitive, faster, and enables a simpler evaluation of chemical cell toxicity. Additionally, it simplifies the study of the reversibility of cell toxicity, i.e., cell recovery, because there is no need to refresh the culture medium since a finite amount of chemicals can be doped and released. We found that the cytotoxicity of [bmim]BF(4) at a concentration of less than 6 mM was reversible for the V79 cell line, because cell morphology and

  17. Phagocytosis by Acanthamoeba castellanii: ionic strength dependence of the probability of cell attachment; ingestion and contact seam morphology.

    PubMed

    Obaray, N; Coakley, W T.

    2001-10-01

    The phagocytosis of glutaraldehyde-fixed horse erythrocytes by Acanthamoeba castellanii has been examined in iso-osmolal phosphate buffered saline/sucrose suspending phases of ionic strength, I, ranging from 0.17 to 0.0017. The erythrocytes were exposed, at a ratio of 15:1, to 5x10(6) amoeba in 0.2 ml volumes. The average number of erythrocytes forming a contact with an amoeba over 30 min (T(30)) was well described by T(30)=5.2 exp(-0.112xI(-0.5)). The index of the exponential 'probability of attachment' term may also be expressed in terms of either surface potential (psi(0)) or the Debye length (kappa(-1)). The probability term is formally similar to a Bolzmann factor. Electron microscopy showed that contact spreading of the amoeba over the erythrocyte took place by formation of discrete contacts and that the lateral separation distance between contacts was 0.66, 1.36 and 1.59 &mgr;m for ionic strengths 0.17, 0.052 and 0.0017, respectively. The direction of change in lateral contact separation distance was consistent with published changes in focal contact separation when amoeba move over glass or when human erythrocyte-erythrocyte adhesion occurs in different ionic strength media. The direction was also consistent with interfacial instability theory predictions for the dependence of localised membrane contact formation on interaction potential. The proportion of attached cells that were subsequently ingested correlated more strongly with the number of contacts formed along the cell-cell contact region (seam) than with the seam length at different ionic strengths.

  18. Membrane-bound heat shock proteins facilitate the uptake of dying cells and cross-presentation of cellular antigen.

    PubMed

    Zhu, Haiyan; Fang, Xiaoyun; Zhang, Dongmei; Wu, Weicheng; Shao, Miaomiao; Wang, Lan; Gu, Jianxin

    2016-01-01

    Heat shock proteins (HSPs) were originally identified as stress-responsive proteins and serve as molecular chaperones in different intracellular compartments. Translocation of HSPs to the cell surface and release of HSPs into the extracellular space have been observed during the apoptotic process and in response to a variety of cellular stress. Here, we report that UV irradiation and cisplatin treatment rapidly induce the expression of membrane-bound Hsp60, Hsp70, and Hsp90 upstream the phosphatidylserine exposure. Membrane-bound Hsp60, Hsp70 and Hsp90 could promote the release of IL-6 and IL-1β as well as DC maturation by the evaluation of CD80 and CD86 expression. On the other hand, Hsp60, Hsp70 and Hsp90 on cells could facilitate the uptake of dying cells by bone marrow-derived dendritic cells. Lectin-like oxidized LDL receptor-1 (LOX-1), as a common receptor for Hsp60, Hsp70, and Hsp90, is response for their recognition and mediates the uptake of dying cells. Furthermore, membrane-bound Hsp60, Hsp70 and Hsp90 could promote the cross-presentation of OVA antigen from E.G7 cells and inhibition of the uptake of dying cells by LOX-1 decreases the cross-presentation of cellular antigen. Therefore, the rapid exposure of HSPs on dying cells at the early stage allows for the recognition by and confers an activation signal to the immune system.

  19. Testis-specific transcriptional regulators selectively occupy BORIS-bound CTCF target regions in mouse male germ cells

    PubMed Central

    Rivero-Hinojosa, Samuel; Kang, Sungyun; Lobanenkov, Victor V.; Zentner, Gabriel E.

    2017-01-01

    Despite sharing the same sequence specificity in vitro and in vivo, CCCTC-binding factor (CTCF) and its paralog brother of the regulator of imprinted sites (BORIS) are simultaneously expressed in germ cells. Recently, ChIP-seq analysis revealed two classes of CTCF/BORIS-bound regions: single CTCF target sites (1xCTSes) that are bound by CTCF alone (CTCF-only) or double CTCF target sites (2xCTSes) simultaneously bound by CTCF and BORIS (CTCF&BORIS) or BORIS alone (BORIS-only) in germ cells and in BORIS-positive somatic cancer cells. BORIS-bound regions (CTCF&BORIS and BORIS-only sites) are, on average, enriched for RNA polymerase II (RNAPII) binding and histone retention in mature spermatozoa relative to CTCF-only sites, but little else is known about them. We show that subsets of CTCF&BORIS and BORIS-only sites are occupied by several testis-specific transcriptional regulators (TSTRs) and associated with highly expressed germ cell-specific genes and histone retention in mature spermatozoa. We also demonstrate a physical interaction between BORIS and one of the analyzed TSTRs, TATA-binding protein (TBP)-associated factor 7-like (TAF7L). Our data suggest that CTCF and BORIS cooperate with additional TSTRs to regulate gene expression in developing male gametes and histone retention in mature spermatozoa, potentially priming certain regions of the genome for rapid activation following fertilization. PMID:28145452

  20. The bglA Gene of Aspergillus kawachii Encodes Both Extracellular and Cell Wall-Bound β-Glucosidases

    PubMed Central

    Iwashita, Kazuhiro; Nagahara, Tatsuya; Kimura, Hitoshi; Takano, Makoto; Shimoi, Hitoshi; Ito, Kiyoshi

    1999-01-01

    We cloned the genomic DNA and cDNA of bglA, which encodes β-glucosidase in Aspergillus kawachii, based on a partial amino acid sequence of purified cell wall-bound β-glucosidase CB-1. The nucleotide sequence of the cloned bglA gene revealed a 2,933-bp open reading frame with six introns that encodes an 860-amino-acid protein. Based on the deduced amino acid sequence, we concluded that the bglA gene encodes cell wall-bound β-glucosidase CB-1. The amino acid sequence exhibited high levels of homology with the amino acid sequences of fungal β-glucosidases classified in subfamily B. We expressed the bglA cDNA in Saccharomyces cerevisiae and detected the recombinant β-glucosidase in the periplasm fraction of the recombinant yeast. A. kawachii can produce two extracellular β-glucosidases (EX-1 and EX-2) in addition to the cell wall-bound β-glucosidase. A. kawachii in which the bglA gene was disrupted produced none of the three β-glucosidases, as determined by enzyme assays and a Western blot analysis. Thus, we concluded that the bglA gene encodes both extracellular and cell wall-bound β-glucosidases in A. kawachii. PMID:10584016

  1. Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

    PubMed Central

    Cook, Alexander B.; Yuen, Jonathan D.; Micheli, Joseph W.; Nasibulin, Albert G.; Zakhidov, Anvar

    2014-01-01

    A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two solution-processed polymeric cells connected in parallel by a transparent carbon nanotubes (CNT) interlayer. This structure includes improvements in fabrication techniques for tandem OPV devices. First the need for ambient-processed cathodes is considered. The CNT anode in the tandem device is tuned via ionic gating to become a common cathode. Ionic gating employs electric double layer charging to lower the work function of the CNT electrode. Secondly, the difficulty of sequentially stacking tandem layers by solution-processing is addressed. The devices are fabricated via solution and dry-lamination in ambient conditions with parallel processing steps. The method of fabricating the individual polymeric cells, the steps needed to laminate them together with a common CNT cathode, and then provide some representative results are described. These results demonstrate ionic gating of the CNT electrode to create a common cathode and addition of current and efficiency as a result of the lamination procedure. PMID:25406721

  2. Ambient method for the production of an ionically gated carbon nanotube common cathode in tandem organic solar cells.

    PubMed

    Cook, Alexander B; Yuen, Jonathan D; Micheli, Joseph W; Nasibulin, Albert G; Zakhidov, Anvar

    2014-11-05

    A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two solution-processed polymeric cells connected in parallel by a transparent carbon nanotubes (CNT) interlayer. This structure includes improvements in fabrication techniques for tandem OPV devices. First the need for ambient-processed cathodes is considered. The CNT anode in the tandem device is tuned via ionic gating to become a common cathode. Ionic gating employs electric double layer charging to lower the work function of the CNT electrode. Secondly, the difficulty of sequentially stacking tandem layers by solution-processing is addressed. The devices are fabricated via solution and dry-lamination in ambient conditions with parallel processing steps. The method of fabricating the individual polymeric cells, the steps needed to laminate them together with a common CNT cathode, and then provide some representative results are described. These results demonstrate ionic gating of the CNT electrode to create a common cathode and addition of current and efficiency as a result of the lamination procedure.

  3. Characterization and Quantification of Electronic and Ionic Ohmic Overpotential and Heat Generation in a Solid Oxide Fuel Cell Anode

    SciTech Connect

    Grew, Kyle N.; Izzo, John R.; Chiu, Wilson K.S.

    2011-08-16

    The development of a solid oxide fuel cell (SOFC) with a higher efficiency and power density requires an improved understanding and treatment of the irreversibilities. Losses due to the electronic and ionic resistances, which are also known as ohmic losses in the form of Joule heating, can hinder the SOFC's performance. Ohmic losses can result from the bulk material resistivities as well as the complexities introduced by the cell's microstructure. In this work, two-dimensional (2D), electronic and ionic transport models are used to develop a method of quantification of the ohmic losses within the SOFC anode microstructure. This quantification is completed as a function of properties determined from a detailed microstructure characterization, namely, the tortuosity of the electronic and ionic phases, phase volume fraction, contiguity, and mean free path. A direct modeling approach at the level of the pore-scale microstructure is achieved through the use of a representative volume element (RVE) method. The correlation of these ohmic losses with the quantification of the SOFC anode microstructure are examined. It is found with this analysis that the contributions of the SOFC anode microstructure on ohmic losses can be correlated with the volume fraction, contiguity, and mean free path.

  4. Ceramides are bound to structural proteins of the human foreskin epidermal cornified cell envelope.

    PubMed

    Marekov, L N; Steinert, P M

    1998-07-10

    An important component of barrier function in human epidermis is contributed by ceramides that are bound by ester linkages to undefined proteins of the cornified cell envelope (CE). In this paper, we have examined the protein targets for the ceramide attachment. By partial saponification of isolated foreskin epidermal CEs followed by limited proteolysis, we have recovered several lipopeptides. Biochemical and mass spectroscopic characterization revealed that all contained near stoichiometric amounts of ceramides of masses ranging from about 690 to 890 atomic mass units, of which six quantitatively major species were common. The array of ceramides was similar to that obtained from pig skin, the composition of which is known, thereby providing strong indirect data for their fatty acid and sphingosine compositions. The recovered peptides accounted for about 20% of the total foreskin CE ceramides. By amino acid sequencing, about 35% of the peptides were derived from ancestral glutamine-glutamate-rich regions of involucrin, an important CE structural protein. Another 18% derived from rod domain sequences of periplakin and envoplakin, which are also known or suspected CE proteins. Other peptides were too short for unequivocal identification. Together, these data indicate that involucrin, envoplakin, periplakin, and possibly other structural proteins serve as substrates for the attachment of ceramides by ester linkages to the CE for barrier function in human epidermis.

  5. Direct Activation of Human Dendritic Cells by Particle-Bound but Not Soluble MHC Class II Ligand

    PubMed Central

    Baleeiro, Renato B.; Wiesmüller, Karl-Heinz; Dähne, Lars; Lademann, Jürgen; Barbuto, José A.; Walden, Peter

    2013-01-01

    Dendritic cells (DCs) are key activators of cellular immune responses through their capacity to induce naïve T cells and sustained effector T cell responses. This capacity is a function of their superior efficiency of antigen presentation via MHC class I and class II molecules, and the expression of co-stimulatory cell surface molecules and cytokines. Maturation of DCs is induced by microbial factors via pattern recognition receptors such as Toll-like receptors, pro-inflammatory cytokines or cognate interaction with CD4+ T cells. Here we show that, unexpectedly, the PanDR helper T cell epitope PADRE, a generic T helper cell antigen presented by a large fraction of HLA-DR alleles, when delivered in particle-bound form induced maturation of human DCs. The DCs that received the particle-bound PADRE displayed all features of fully mature DCs, such as high expression of the co-stimulatory molecules CD80, CD86, CD83, the MHC-II molecule HLA-DR, secretion of high levels of the biologically active IL-12 (IL-12p70) and induction of vigorous proliferation of naïve CD4+ T cells. Furthermore, the maturation of DCs induced by particle-bound PADRE was shown to involve sphingosine kinase, calcium signaling from internal sources and downstream signaling through the MAP kinase and the p72syk pathways, and finally activation of the transcription factor NF-κB. Based on our findings, we propose that particle-bound PADRE may be used as a DC activator in DC-based vaccines. PMID:23658796

  6. Solid-state dye-sensitized solar cells using polymerized ionic liquid electrolyte with platinum-free counter electrode.

    PubMed

    Kawano, Ryuji; Katakabe, Toru; Shimosawa, Hironobu; Nazeeruddin, Md Khaja; Grätzel, Michael; Matsui, Hiroshi; Kitamura, Takayuki; Tanabe, Nobuo; Watanabe, Masayoshi

    2010-02-28

    A polymerized ionic liquid electrolyte and platinum-free counter electrode are employed for solid-state DSSCs. We are able to prepare a thin polymer electrolyte layer on nanocrystalline TiO(2) in order to reduce the cell resistance. In addition, an electron conductive polymer (PEDOT/PSS) or a single-wall carbon nanotube gel is used with the cell as an inexpensive counter electrode instead of platinum. The overall photon-to-current conversion efficiency was 3.7% in this study.

  7. Ionic mechanisms for the transduction of acidic stimuli in rabbit carotid body glomus cells.

    PubMed Central

    Rocher, A; Obeso, A; Gonzalez, C; Herreros, B

    1991-01-01

    1. The release of [3H]dopamine (DA) in response to inhibition of the Na+ pump or to intracellular acid load was studied in rabbit carotid bodies (CB) previously incubated with the precursor [3H]tyrosine. The ionic requirements of the release response and the involvement of specific ion transport systems were investigated. 2. Inhibition of the Na+ pump, by incubating the CB with ouabain or in K(+)-free medium, evokes a DA release response which requires the presence of Na+ and Ca2+ in the medium and is insensitive to nisoldipine. This suggests that the response is triggered by entry of external Ca2+ through Na(+)-Ca2+ exchange, a consequence of the increase in intracellular Na+ resulting from inhibition of the pump. 3. Incubation of the CB in medium equilibrated with 20% CO2 at pH 6.6, or in medium containing the protonophore dinitrophenol (DNP) or the weak acid propionate, elicits a DA release response which requires also the presence of Na+ and Ca2+ in the medium and is insensitive to dihydropyridines. 4. Ethylisopropylamiloride (EIPA), an inhibitor of the Na(+)-H+ exchanger, markedly decreases the release response elicited by DNP or propionate in bicarbonate-free medium, but has not any effect in bicarbonate-buffered medium. In the latter condition, the EIPA-insensitive release of DA is inhibited by reducing the HCO3- concentration in the medium to 2 mM or by removal of Cl-, suggesting that in bicarbonate-buffered medium a Na(+)-dependent HCO3(-)-Cl- exchanger is involved in the release response. 5. It is concluded that the release of DA by the chemoreceptor cells in response to acidic stimulation is triggered by entry of external Ca2+ through Na(+)-Ca2+ exchange. This exchange is promoted by the increase of intracellular Na+ that results from the operation of Na(+)-coupled H(+)-extruding mechanisms activated by the acid load. PMID:1668755

  8. Fluorescent avidin-bound silver particle: a strategy for single target molecule detection on a cell membrane.

    PubMed

    Zhang, Jian; Fu, Yi; Liang, Dong; Zhao, Richard Y; Lakowicz, Joseph R

    2009-02-01

    Cy5-avidin conjugate-bound silver nanoparticles were prepared as a fluorescence molecular reagent for the cell imaging. Compared with the metal-free avidin conjugate, the avidin-metal complex was observed to display a stronger emission intensity, shorter lifetime, and better photostability. The avidin-metal complexes were conjugated with the biotin-sites on the surfaces of PM1 cell lines, and the cell images were recorded using scanning confocal microscopy. It was noticed that the avidin-metal complexes bound on the cell surfaces could be identified as the isolated emission spots distinct from the cellular autofluorescence. The emission intensity over the cell image was increased with an increase of the number of avidin-metal complexes on the cell surface but the lifetime was decreased. A quantitative regression curve was achieved between the amount of avidin-metal complex on the cell surface and the emission intensity or lifetime over the entire cell image. On the basis of this curve, we expect to develop an approach that can be used to quantify the amount of target molecules on the cell surfaces using the cell intensity and lifetime images at the single cell level.

  9. Dynamics of intracellular ionic concentrations in single living cells using videomicrofluorometry: application to pHi variations

    NASA Astrophysics Data System (ADS)

    Viallet, Pierre M.; Yassine, Mohamed; Salmon, Jean-Marie; Vigo, Jean

    1996-01-01

    The intracellular concentration of ions such as H+, Mg2+, Ca2+, is known to monitor the activity of many fundamental enzymes. Furthermore these ions are generally considered as intracellular messengers involved in the transduction of extracellular signals. Recent technological progress, occulting the physicochemical properties of the probe, led to the feeling that accurate data on microvolumes are instantly accessible. Unfortunately fluorescent probes are supposed to fill up conflicting requirements for ionic affinity, absence of fading and intracellular calibration. Such a situation generally precludes the use of the simplest methods of data acquisition and treatment. This paper is based on the use of microspectrofluorometry, resolution of single cell complex fluorescence spectrum, and videomicrofluorometry. The methods of data handling allow us to demonstrate that most of the problems met in intracellular calibration come from the fighting of cells against the modification of the extracellular pH. Using these techniques allows us to restrict the need of comparison between results in cuvettes and intracellular results to the physiological pH range. A consequence of such an approach is that the effect with time of known concentrations of amiloride and nigericin on pHi became accessible. Data is presented allowing us to get information on the behavior of the ionic channels and/or cation/H+ exchangers involved in the pHi regulation. Such a method leads the way to direct investigations and monitoring of the different processes of regulation of the intracellular ionic concentrations in different cell lines at the level of single cells. Using different specific modifiers (activators or blocking agents) and convenient specific fluorescent probes, the efficiency of such pathways is expected to be checked at will. Compared to the patch clamp techniques, the method can be extended to the study of pathways located on the inner cell membranes.

  10. Voltage-dependent ionic channels in differentiating neural precursor cells collected from adult mouse brains six hours post-mortem.

    PubMed

    Bellardita, Carmelo; Bolzoni, Francesco; Sorosina, Melissa; Marfia, Giovanni; Carelli, Stephana; Gorio, Alfredo; Formenti, Alessandro

    2012-04-01

    A novel type of adult neural precursor cells (NPCs) has been isolated from the subventricular zone of the mouse 6 hr after animal death (T6-NPCs). This condition is supposed to select hypoxia-resistant cells of scientific and clinical interest. Ionic channels are ultimately the expression of the functional maturation of neurons, so the aim of this research was to characterize the pattern of the main voltage-dependent ionic channels in T6-NPCs differentiating to a neuronal phenotype, comparing it with NPCs isolated soon after death (T0-NPCs). T6- and T0-NPCs grow in medium containing epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). Differentiation was performed in small wells without the addition of growth factors, in the presence of adhesion molecules, fetal bovine serum, and leukemia inhibitory factor. Ionic currents, recorded by means of whole-cell patch-clamp, namely, I(Ca2+) HVA, both L- and non-L-type, I(K+) delayed rectifying, I(K+) inward rectifier, transient I(K+A) , and TTX-sensitive I(Na+) have been found, although Na(+) currents were found in only a small percentage of cells and after the fifth week of differentiation. No significant differences in current types, density, orcell capacitance were observed between T6-NPCs and T0-NPCs. The sequence in which the markers appear in new neural cells is not necessarily a fixed program, but the discrepancies in morphological, biochemical, and electrophysiological maturation of mouse NPCs to neurons, possibly different in vivo, suggest that the various steps of the differentiation are independently regulated. Therefore, in addition to morphological and biochemical data, functional tests should be considered for characterizing the maturation of neurons.

  11. Protein-bound polysaccharide activates dendritic cells and enhances OVA-specific T cell response as vaccine adjuvant

    PubMed Central

    Engel, Abbi L.; Sun, Guan-Cheng; Gad, Ekram; Rastetter, Lauren R.; Strobe, Katie; Yang, Yi; Dang, Yushe; Disis, Mary L; Lu, Hailing

    2013-01-01

    Protein-bound polysaccharide-K (PSK) is a hot water extract from Trametes versicolor mushroom. It has been used traditionally in Asian countries for its immune stimulating and anti-cancer effects. We have recently found that PSK can activate toll-like receptor 2 (TLR2). TLR2 is highly expressed on dendritic cells (DC), so the currently study was undertaken to evaluate the effect of PSK on DC activation and the potential of using PSK as a vaccine adjuvant. In vitro experiments using mouse bone marrow-derived DC (BMDC) demonstrated that PSK induces DC maturation as shown by dose-dependent increase in the expression of CD80, CD86, MHCII, and CD40. PSK also induces the production of multiple inflammatory cytokines by DC, including IL-12, TNF-α, and IL-6, at both mRNA and protein levels. In vivo experiments using PSK as an adjuvant to OVAp323-339 vaccine showed that PSK as adjuvant leads to enlarged draining lymph nodes with higher number of activated DC. PSK also stimulates proliferation of OVA-specific T cells, and induces T cells that produce multiple cytokines, IFN-γ, IL-2, and TNF-α. Altogether, these results demonstrate the ability of PSK to activate DC in vitro and in vivo and the potential of using PSK as a novel vaccine adjuvant. PMID:23735481

  12. Preparation of nano/macroporous polycaprolactone microspheres for an injectable cell delivery system using room temperature ionic liquid and camphene.

    PubMed

    Kim, Seong Yeol; Hwang, Ji-Young; Shin, Ueon Sang

    2016-03-01

    The nano/macroporous polycaprolactone (PCL) microspheres with cell active surfaces were developed as an injectable cell delivery system. Room temperature ionic liquid (RTIL) and camphene were used as a liquid mold and a porogen, respectively. Various-sized spheres of 244-601μm with pores of various size and shape of 0.02-100μm, were formed depending on the camphene/RTIL ratio (0.8-2.6). To give cell activity, the surface of porous microspheres were further modified with nerve growth factors (NGF) containing gelatin to give a thin NGF/gelatin layer, to which the neural progenitor cells (PC-12) attached and extended their neurites on to the surface layers of the microspheres. The developed microspheres may be potentially applicable as a neuronal cell delivery scaffold for neuron tissue engineering.

  13. Acrylic microspheres in vivo. X. Elimination of circulating cells by active targeting using specific monoclonal antibodies bound to microparticles

    SciTech Connect

    Laakso, T.; Andersson, J.; Artursson, P.; Edman, P.; Sjoeholm, I.

    1986-01-13

    The elimination from the blood of /sup 51/Cr-labelled mouse erythrocytes modified with trinitrophenyl (TNP) groups was followed in mice. After 24 hours, when a stable concentration of the labelled erythrocytes has been attained, monoclonal anti-TNP-antibodies were given intravenously, either in free, soluble form, or bound to microparticles containing immobilized protein A. The anti-TNP-antibodies induced a rapid elimination of the TNP- and /sup 51/Cr-labelled erythrocytes. Over the 8-hours time period studied, the elimination rate was significantly faster when the antibodies were administered bound to the particles. After the elimination of the target cells, the radioactivity was found in the liver, spleen and bone marrow. These results and relevant control experiments indicate that a solid carrier (1) can be directed to a specific target cell with a specific antibody and (2) can induce a rapid elimination of the target cell from the circulation. 31 references, 1 figure, 2 tables.

  14. Characterization and Quantification of Electronic and Ionic Ohmic Overpotential and Heat Generation in a Solid Oxide Fuel Cell Anode

    SciTech Connect

    Grew, Kyle N.; Izzo, Jr., John R.; Chiu, W. K. S.

    2011-01-01

    The development of a solid oxide fuel cell (SOFC) with a higher efficiency and power density requires an improved understanding and treatment of the irreversibilities. Losses due to the electronic and ionic resistances, which are also known as ohmic losses in the form of Joule heating, can hinder the SOFC’s performance. Ohmic losses can result from the bulk material resistivities as well as the complexities introduced by the cell’s microstructure. In this work, two-dimensional (2D), electronic and ionic transport models are used to develop a method of quantification of the ohmic losses within the SOFC anode microstructure. This quantification is completed as a function of properties determined from a detailed microstructure characterization, namely, the tortuosity of the electronic and ionic phases, phase volume fraction, contiguity, and mean free path. A direct modeling approach at the level of the pore-scale microstructure is achieved through the use of a representative volume element (RVE) method. The correlation of these ohmic losses with the quantification of the SOFC anode microstructure are examined. It is found with this analysis that the contributions of the SOFC anode microstructure on ohmic losses can be correlated with the volume fraction, contiguity, and mean free path.

  15. Anionic structure-dependent photoelectrochemical responses of dye-sensitized solar cells based on a binary ionic liquid electrolyte.

    PubMed

    Hao, Feng; Lin, Hong; Liu, Yizhu; Li, Jianbao

    2011-04-14

    Room temperature ionic liquids (RTILs) have been used as electrolytes to investigate the anionic structure dependence of the photoelectrochemical responses of dye-sensitized solar cells (DSCs). A series of RTILs with a fixed cation structure coupling with various anion structures are employed, in which 1-methyl-3-propylimidazolium iodide (PMII) and I(2) are dissolved as redox couples. It is found that both the diffusivity of the electrolyte and the photovoltaic performance of the device show a strong dependence on the fluidity of the ionic liquids, which is primarily altered by the anion structure. Further insights into the structure-dependent physical properties of the employed RTILs are discussed in terms of the reported van der Waals radius, the atomic charge distribution over the anion backbones, the interaction energy of the anion and cation, together with the existence of ion-pairs and ion aggregates. Particularly, both the short-circuit photocurrent and open-circuit voltage exhibit obvious fluidity dependence. Electrochemical impedance and intensity-modulated photovoltage/photocurrent spectroscopy analysis further reveal that increasing the fluidity of the ionic liquid electrolytes could significantly decrease the diffusion resistance of I(3)(-) in the electrolyte, and retard the charge recombination between the injected electrons with triiodide in the high-viscous electrolyte, thus improving the electron diffusion length in the device, as well as the photovoltaic response. However, the variation of the electron diffusion coefficients is trivial primarily due to the effective charge screening of the high cation concentration.

  16. Iodine-Pseudohalogen Ionic Liquid-Based Electrolytes for Quasi-Solid-State Dye-Sensitized Solar Cells.

    PubMed

    Lennert, Annkatrin; Sternberg, Michelle; Meyer, Karsten; Costa, Rubén D; Guldi, Dirk M

    2017-10-04

    In the current work, novel symmetrically alkyl-substituted imidazolium-based ionic liquids have been synthesized featuring either iodide (I(-)) or selenocyanate (SeCN(-)) as counteranions. Physicochemical assays based on spectroscopy and electrochemistry techniques have been performed to identify the best ionic liquid for application as electrolytes in quasi-solid-state dye-sensitized solar cells (qssDSSC). The latter were mixed with additives such as 4-tert-butylpyridine (4tbpy) and guanidinium thiocyanate (GuSCN) to optimize electrode surface coverage, ionic diffusion, and dye regeneration. In addition, we demonstrate that electrolytes containing a mixture of I2 and (SeCN)2 enhance the open-circuit voltage of the final quasi-solid-state device by up to 70 mV. As such, iodine-pseudohalogen electrolytes reveal in qssDSSCs a good balance between dye regeneration and hole transport and, in turn, enhance the overall solar energy conversion efficiency by 70% with respect to reference qssDSSCs with iodine-based electrolytes. Finally, devices with the iodine-pseudohalogen electrolyte show a 1000 h stable efficiency of 7-8% under outdoor temperature operation conditions and 1 sun illumination.

  17. Nanocomposite semi-solid redox ionic liquid electrolytes with enhanced charge-transport capabilities for dye-sensitized solar cells.

    PubMed

    Rutkowska, Iwona A; Marszalek, Magdalena; Orlowska, Justyna; Ozimek, Weronika; Zakeeruddin, Shaik M; Kulesza, Pawel J; Grätzel, Michael

    2015-08-10

    The ability of Pt nanostructures to induce the splitting of the II bond in iodine (triiodide) molecules is explored here to enhance electron transfer in the iodine/iodide redox couple. Following the dispersal of Pt nanoparticles at 2 % (weight) level, charge transport was accelerated in triiodide/iodide-containing 1,3-dialkylimidazolium room-temperature ionic liquid. If both Pt nanoparticles and multi-walled carbon nanotubes were introduced into the ionic-liquid-based system, a solid-type (nonfluid) electrolyte was obtained. By using solid-state voltammetric (both sandwich-type and microelectrode-based) methodology, the apparent diffusion coefficients for charge transport increased to approximately 1×10(-6)  cm(2)  s(-1) upon the incorporation of the carbon-nanotube-supported iodine-modified Pt nanostructures. A dye-sensitized solar cell comprising TiO2 covered with a heteroleptic Ru(II) -type sensitizer (dye) and the semisolid triiodide/iodide ionic liquid electrolyte admixed with carbon-nanotube-supported Pt nanostructures yielded somewhat higher power conversion efficiencies (up to 7.9 % under standard reporting conditions) than those of the analogous Pt-free system. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Multilayered YSZ/GZO films with greatly enhanced ionic conduction for low temperature solid oxide fuel cells.

    PubMed

    Li, Bin; Zhang, Jiaming; Kaspar, Tiffany; Shutthanandan, Vaithiyalingam; Ewing, Rodney C; Lian, Jie

    2013-01-28

    Strain confinement in heterostructured films significantly affects ionic conductivity of the electrolytes for solid oxide fuel cells based on a multi-layered design strategy. Nearly ideal tensile strain can be achieved by a dedicated manipulation of the lattice mismatch between adjacent layers and fine control of the layer thicknesses to minimize the formation of dislocations and thus to achieve optimized ionic conduction. This strategy was demonstrated by a model system of multilayered 8 mol%Y(2)O(3) stabilized ZrO(2) (YSZ) with Gd(2)Zr(2)O(7) (GZO) films, which were epitaxially grown on Al(2)O(3) (0001) substrates by pulsed laser deposition (PLD) with the {111} planes of YSZ/GZO along the Al(2)O(3) [0 1 -1 0] direction. The tensile strain (3%) resulting from the lattice mismatch can be confined in individual YSZ layers with the formation of a coherent, dislocation-free interface upon the manipulation of the layer thickness below a critical value, e.g., down to 5 nm. The strained heterostructure displays a two order-of-magnitude increase in oxide-ion conductivity as compared with bulk YSZ, and a high ionic conductivity of 0.01 S cm(-1) at 475 °C can be achieved, five times greater than that of Gd-doped ceria/zirconia. The approach of strain confinement by fine control of lattice mismatch and layer thickness represents a promising strategy in developing advanced electrolytes enabling the miniaturization of solid-state ionic devices that can be operated at low temperatures below 500 °C.

  19. Applications of ionic liquids.

    PubMed

    Patel, Divia Dinesh; Lee, Jong-Min

    2012-06-01

    Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas.

  20. Recognition of core and flanking amino acids of MHC class II-bound peptides by the T cell receptor.

    PubMed

    Sant'Angelo, Derek B; Robinson, Eve; Janeway, Charles A; Denzin, Lisa K

    2002-09-01

    CD4 T cells recognize peptides bound to major histocompatibility complex (MHC) class II molecules. Most MHC class II molecules have four binding pockets occupied by amino acids 1, 4, 6, and 9 of the minimal peptide epitope, while the residues at positions 2, 3, 5, 7, and 8 are available to interact with the T cell receptor (TCR). In addition MHC class II bound peptides have flanking residues situated outside of this peptide core. Here we demonstrate that the flanking residues of the conalbumin peptide bound to I-A(k) have no effect on recognition by the D10 TCR. To study the role of peptide flanks for recognition by a second TCR, we determined the MHC and TCR contacting amino acids of the I-A(b) bound Ealpha peptide. The Ealpha peptide is shown to bind I-A(b) using four alanines as anchor residues. TCR recognition of Ealpha peptides with altered flanking residues again suggested that, in general, no specific interactions occurred with the peptide flanks. However, using an HLA-DM-mediated technique to measure peptide binding to MHC class II molecules, we found that the peptide flanking residues contribute substantially to MHC binding.

  1. Ionic conductivity studies of solid oxide fuel cell electrolytes and theoretical modeling of an entire solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Pornprasertsuk, Rojana

    Because of the steep increase in oil prices, the global warming effect and the drive for energy independence, alternative energy research has been encouraged worldwide. The sustainable fuels such as hydrogen, biofuel, natural gas, and solar energy have attracted the attention of researchers. To convert these fuels into a useful energy source, an energy conversion device is required. Fuel cells are one of the energy conversion devices which convert chemical potentials into electricity. Due to their high efficiency, the ease to scale from 1 W range to megawatts range, no recharging requirement and the lack of CO2 and NOx emission (if H2 and air/O 2 are used), fuel cells have become a potential candidate for both stationary power generators and portable applications. This thesis has been focused primarily on solid oxide fuel cell (SOFC) studies due to its high efficiency, varieties of fuel choices, and no water management problem. At the present, however, practical applications of SOFCs are limited by high operating temperatures that are needed to create the necessary oxide-ion vacancy mobility in the electrolyte and to create sufficient electrode reactivities. This thesis introduces several experimental and theoretical approaches to lower losses both in the electrolyte and the electrodes. Yttria stabilized zirconia (YSZ) is commonly used as a solid electrolyte for SOFCs due to its high oxygen-ion conductivity. To improve the ionic conductivity for low temperature applications, an approach that involves dilating the structure by irradiation and introducing edge dislocations into the electrolyte was studied. Secondly, to understand the activation loss in SOFC, the kinetic Monte Carlo (KMC) technique was implemented to model the SOFC operation to determining the rate-limiting step due to the electrodes on different sizes of Pt catalysts. The isotope exchange depth profiling technique was employed to investigate the irradiation effect on the ionic transport in different

  2. Expression of platelet-bound stromal-cell derived factor-1 (SDF-1) and number of CD34(+) progenitor cells in patients with congestive heart failure.

    PubMed

    Jorbenadze, Rezo; Schleicher, Erwin; Bigalke, Boris; Stellos, Konstantinos; Gawaz, Meinrad

    2014-01-01

    Platelet-bound stromal cell-derived factor-1 (SDF-1) plays a crucial role in attachment of circulating CD34(+) progenitor cells to the vascular wall, facilitating tissue healing after injury. However there is no evidence about expression of platelet-bound SDF-1 in patients with congestive heart failure (CHF). The aim of our study was to evaluate expression of platelet-bound SDF-1 and number of CD34(+) progenitor cells in patients with CHF. Forty-eight patients with idiopathic dilated cardiomyopathy (DCM) and 61 patients with ischaemic cardiomyopathy (ICM) were consecutively enrolled into the study. Blood taken from 109 consecutive patients was studied for surface expression of platelet-bound SDF-1 and number of CD34(+) progenitor cells by flow cytometry. The highest expression of platelet-bound SDF-1 was observed in patients with severe impairment of left ventricular systolic function compared with patients with mild or moderate impairment of left ventricular systolic function (mild vs. moderate vs. severe impairment of left ventricular systolic function: MFI ± SD: 35.6 ± 34 vs. 101.45 ± 73 vs. 124.86 ± 86.7, Kruskal-Wallis p < 0.001). Similar to platelet-bound SDF-1 number of CD34(+) progenitor cells was the highest in severe impairment of left ventricular systolic function (mild vs. moderate vs. severe impairment of left ventricular systolic function: mean ± SD: 260.4 ± 177.5 vs. 580.7 ± 340.5 vs. 640.82 ± 370.6, Kruskal-Wallis p < 0.001). Platelet-bound SDF-1 expression was associated with number of circulating CD34(+) progenitor cells (r = 0.454, p < 0.001) in patients with CHF. Expression of platelet-bound SDF-1 and number of CD34(+) cells were higher in patients with DCM compared with patients with ICM (p < 0.001 for both) and inversely correlated with age and aspirin therapy. Platelet-bound SDF-1 and CD34(+) progenitor cells are especially increased in patients with severe impairment of left

  3. Regional distribution of ionic currents and membrane voltage responses of type II hair cells in the vestibular neuroepithelium.

    PubMed

    Weng, T; Correia, M J

    1999-11-01

    Basolateral ionic currents and membrane voltage responses were studied in pigeon vestibular type II hair cells using a thin slice through either the semicircular canal (SCC) crista or utricular macular epithelium. Whole cell tight-seal patch-clamp recording techniques were used. Current-clamp and voltage-clamp studies were carried out on the same cell. One hundred ten cells were studied in the peripheral (Zone I) and central (Zone III) zones of the SCC crista, and 162 cells were studied in the striolar (S Zone) and extrastriolar (ES Zone) zones of the utricular macula. One of the major findings of this paper is that hair cells with fast activation kinetics of their outward currents are found primarily in one region of the SCC crista and utricular macula, whereas hair cells with slow activation kinetics are found in a different region. In Zone I of the crista, 95% of the cells have fast activation kinetics ("fast" cells) and in Zone III of the crista, 86% of the cells have slow activation kinetics ("slow" cells). In the utricular macula slice, 100% of the cells from the S Zone are slow cells, whereas 86% of the cells from the ES Zones are fast cells. Oscillation frequency (f) and quality factor (Q) of the damped oscillations of the membrane potential during extrinsic current injections were studied in hair cells in the different regions. The slow cells in Zone III and in the S Zone have a statistically significantly lower f, as a function of the amplitude of injected current, when compared with the fast cells in Zone I and the ES Zone. Although Q varied over a small range and was <2.6 for all cells tested, there was a statistically significant difference between Q for the membrane oscillations of the slow cells and fast cells in response to a range of current injections.

  4. Red cell volume regulation: the pivotal role of ionic strength in controlling swelling-dependent transport systems.

    PubMed

    Motais, R; Guizouarn, H; Garcia-Romeu, F

    1991-10-10

    A volume increase of trout erythrocytes can be induced either by beta-adrenergic stimulation of a Na+/H+ antiport in an isotonic medium (isotonic swelling) or by suspending red cells in an hypotonic medium (hypotonic swelling). In both cases cells regulate their volume by a loss of osmolytes via specific pathways. After hypotonic swelling several volume-dependent pathways were activated allowing K+, Na+, taurine and choline to diffuse. All these pathways were fully inhibited by furosemide and inhibitors of the anion exchanger (DIDS, niflumic acid), and the K+ loss was mediated essentially via a 'Cl(-)-independent' pathway. After isotonic swelling, the taurine, choline and Na+ pathways were practically not activated and the K+ loss was strictly 'Cl(-)-dependent'. Thus cellular swelling is a prerequisite for activation of these pathways but, for a given volume increase, the degree of activation and the degree of anion-dependence of the K+ pathway depend on the nature of the stimulus, whether hormonal or by reduction of osmolality. It appears that the pattern of the response induced by hormonal stimulation is not triggered by either cellular cAMP (since it can be reproduced in the absence of hormone by isotonic swelling in an ammonium-containing saline) or by the tonicity of the medium in which swelling occurs since after swelling in an isotonic medium containing urea, the cells adopt the regulatory pattern normally observed after hypotonic swelling. We demonstrated that the stimulus is the change in cellular ionic strength induced by swelling: when ionic strength drops, the cells adopt the hypotonic swelling pattern; when ionic strength increases, the isotonic swelling pattern is activated. To explain this modulating effect of ionic strength a speculative model is proposed, which also allows the integration of two further sets of experimental results: (i) all the volume-activated transport systems are blocked by inhibitors of the anion exchanger and (ii) a Cl

  5. An increase in the content of cell wall-bound phenolics correlates with the productivity of triticale under soil drought.

    PubMed

    Hura, Tomasz; Hura, Katarzyna; Dziurka, Kinga; Ostrowska, Agnieszka; Bączek-Kwinta, Renata; Grzesiak, Maciej

    2012-11-15

    The objective of this study was to investigate whether the content of cell wall-bound phenolics can simultaneously influence both the productivity and the water status of triticale under soil drought conditions. Two parallel treatments were carried out. The T1 treatment involved plants being subjected to soil drought twice, during the tillering phase and then during the flowering phase. The T2 treatment included drought only during the flowering phase. After T1 treatment, the majority of cultivars exhibited better PSII functioning at the flowering phase in comparison to T2, which could be related to better adaptation of the photosynthetic apparatus to leaf dehydration. Simultaneously, the higher activity of the photosynthetic apparatus of flag leaves for T1 was significantly correlated with the higher content of cell wall-bound phenolics. The dry mass of plants was markedly lower in the T1 treatment and was correlated with a higher content of cell wall-bound phenolics. Moreover, cultivars subjected to the T1 treatment showed a significantly higher water content in comparison to the T2 treatment. The delay in the leaf rolling and the ageing of plants in the T1 treatment, which induced a higher level of cell wall-bound phenolics, was visual proof of the improvement in the water status of plants. Phenolic compounds that form cross-bridges with carbohydrates of the cell wall can be considered a more effective biochemical protective mechanism than free phenolics during the dehydration of leaves. This potentially higher level of effectiveness is likely the result of the double action of phenolic compounds, both as photoprotectors of the photosynthetic apparatus and hydrophobic stabilizers, preventing water loss from the apoplast.

  6. Transport of iron bound to recombinant human lactoferrin from rice and iron citrate across Caco-2 cell monolayers.

    PubMed

    Conesa, Celia; Pocoví, Coloma; Pérez, María-Dolores; Calvo, Miguel; Sánchez, Lourdes

    2009-12-01

    The possibility of using recombinant human lactoferrin from rice (rhLF) makes it necessary to study its differences from the protein of milk. In this work, the binding of different iron-saturated forms of rhLF to Caco-2 cells was studied. Iron-saturated rhLF bound in higher proportion than the apo-form, but, the data obtained for specific binding were not compatible with receptor-mediated binding. Competition assays showed the same binding capacity for human milk lactoferrin as for rhLF to Caco-2 cells. Another basic protein of milk, lactoperoxidase, was found to compete with rhLF for binding to Caco-2 cell membranes, suggesting an electrostatic interaction. The transport of iron ((59)Fe) bound to rhLF and to citrate and the transport of rhLF ((125)I-labeled) were studied on Caco-2 monolayers. Transport of iron was found to be significantly greater when bound to citrate than to rhLF. The amount of intact lactoferrin that traversed the Caco-2 monolayers was very low, suggesting degradation of it across these cells.

  7. Assessment of the Effects of Flow Rate and Ionic Strength on Microbial Fuel Cell Performance Using Electrochemical Impedance Spectroscopy

    SciTech Connect

    Aaron, D; Tsouris, Costas; Hamilton, Choo Yieng; Borole, Abhijeet P

    2010-01-01

    Impedance changes of the anode, cathode and solution were examined for a microbial fuel cell (MFC) under varying conditions in order to improve its performance. An MFC inoculated with a pre-enriched microbial culture resulted in a startup time of ten days. Over this period, the anode impedance decreased below the cathode impedance, suggesting a cathode limited power output. Decreasing the anode flow rate did not impact the anode impedance significantly, while it increased the cathode impedance by 65% . Reducing the anode-medium ionic strength from 100% to 10% increased the cathode impedance by 48%.

  8. Preparation, characterization and single cell testing of new ionic conducting polymers for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Escribano, P. G.; del Río y, C.; Acosta, J. L.

    In this work, heterogeneous sulfonation and both, structural and electrical characterization of a mixture composed on block copolymer ionomers (HSBS and EPDM) and commercial silica, are studied. The incorporation of sulfonic groups was checked by infrared spectroscopy (FTIR-ATR). Microstructure was studied by means of dynamic mechanical analysis (DMA). Also, water uptake and methanol crossover were determined, and the results were compared with those of Nafion ® 117. Electrical behavior was recorded by means of electrochemical impedance spectroscopy (EIS) at different hydration times. Results show that sulfonation of the styrene rings has effectively occurred. Conductivity values are similar to Nafion and they improve with hydration time. Methanol crossover is lower than in Nafion. Finally, a single complete proton exchange membrane fuel cell (PEMFC) as a whole was tested obtaining the polarization and power curves at different temperatures and pressures, and modeling it by an electrical equivalent circuit (EC) in the symmetrical mode (SM) configuration using the EIS technique. This study offers a physical interpretation relating physical parameters to several processes occurring in the system. Power density values are higher than in Nafion.

  9. Synthesis and performance of novel anion exchange membranes based on imidazolium ionic liquids for alkaline fuel cell applications

    NASA Astrophysics Data System (ADS)

    Fang, Jun; Lyu, Ming; Wang, Xin; Wu, Yongbin; Zhao, Jinbao

    2015-06-01

    Novel anion exchange membranes (AEMs) based on two types of imidazolium ionic liquids, 1-vinyl-3-methylimidazolium iodide [VMI]I and 1-vinyl-3-butylimidazolium bromide [VBI]Br, have been synthesized by copolymerization. The obtained membranes are characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal and chemical stability. The conductivity reaches 0.0226 Scm-1 at 30 °C. All the membranes show excellent thermostability. The membranes are stable in 10 mol L-1 NaOH solution at 60 °C for 120 h without obvious changes in ion conductivity. Fuel cell performance using the resulting membrane has been investigated. The open circuit voltage (OCV) of the H2/O2 fuel cell is 1.07 V. A peek power density of 116 mW cm-2 is obtained at a current density of 230 mA cm-2 at 60 °C. The results demonstrate the brilliant prospect of the developed membranes for alkaline fuel cell applications.

  10. Ionic Blocks

    ERIC Educational Resources Information Center

    Sevcik, Richard S.; Gamble, Rex; Martinez, Elizabet; Schultz, Linda D.; Alexander, Susan V.

    2008-01-01

    "Ionic Blocks" is a teaching tool designed to help middle school students visualize the concepts of ions, ionic compounds, and stoichiometry. It can also assist high school students in reviewing their subject mastery. Three dimensional blocks are used to represent cations and anions, with color indicating charge (positive or negative) and size…

  11. Ionic Blocks

    ERIC Educational Resources Information Center

    Sevcik, Richard S.; Gamble, Rex; Martinez, Elizabet; Schultz, Linda D.; Alexander, Susan V.

    2008-01-01

    "Ionic Blocks" is a teaching tool designed to help middle school students visualize the concepts of ions, ionic compounds, and stoichiometry. It can also assist high school students in reviewing their subject mastery. Three dimensional blocks are used to represent cations and anions, with color indicating charge (positive or negative) and size…

  12. The dynamic behavior of thin-film ionic transition metal complex-based light-emitting electrochemical cells

    SciTech Connect

    Meier, Sebastian B. E-mail: wiebke.sarfert@siemens.com; Hartmann, David; Sarfert, Wiebke E-mail: wiebke.sarfert@siemens.com; Winnacker, Albrecht

    2014-09-14

    Light-emitting electrochemical cells (LECs) have received increasing attention during recent years due to their simple architecture, based on solely air-stabile materials, and ease of manufacture in ambient atmosphere, using solution-based technologies. The LEC's active layer offers semiconducting, luminescent as well as ionic functionality resulting in device physical processes fundamentally different as compared with organic light-emitting diodes. During operation, electrical double layers (EDLs) form at the electrode interfaces as a consequence of ion accumulation and electrochemical doping sets in leading to the in situ development of a light-emitting p-i-n junction. In this paper, we comment on the use of impedance spectroscopy in combination with complex nonlinear squares fitting to derive key information about the latter events in thin-film ionic transition metal complex-based light-emitting electrochemical cells based on the model compound bis-2-phenylpyridine 6-phenyl-2,2´-bipyridine iridium(III) hexafluoridophosphate ([Ir(ppy)₂(pbpy)][PF₆]). At operating voltages below the bandgap potential of the ionic complex used, we obtain the dielectric constant of the active layer, the conductivity of mobile ions, the transference numbers of electrons and ions, and the thickness of the EDLs, whereas the transient thickness of the p-i-n junction is determined at voltages above the bandgap potential. Most importantly, we find that charge transport is dominated by the ions when carrier injection from the electrodes is prohibited, that ion movement is limited by the presence of transverse internal interfaces and that the width of the intrinsic region constitutes almost 60% of the total active layer thickness in steady state at a low operating voltage.

  13. Iron-sulfur Proteins Are the Major Source of Protein-bound Dinitrosyl Iron Complexes Formed in Escherichia coli Cells under Nitric Oxide Stress

    PubMed Central

    Landry, Aaron P.; Duan, Xuewu; Huang, Hao; Ding, Huangen

    2011-01-01

    Protein-bound dinitrosyl iron complexes (DNICs) have been observed in prokaryotic and eukaryotic cells under nitric oxide (NO) stress. The identity of proteins that bind DNICs, however, still remains elusive. Here we demonstrate that iron-sulfur proteins are the major source of protein-bound DNICs formed in Escherichia coli cells under NO stress. Expression of recombinant iron-sulfur proteins, but not the proteins without iron-sulfur clusters, almost doubles the amount of protein-bound DNICs formed in E. coli cells after NO exposure. Purification of recombinant proteins from the NO-exposed E. coli cells further confirms that iron-sulfur proteins, but not the proteins without iron-sulfur clusters, are modified forming protein-bound DINCs. Deletion of the iron-sulfur cluster assembly proteins IscA and SufA to block the [4Fe-4S] cluster biogenesis in E. coli cells largely eliminates the NO-mediated formation of protein-bound DNICs, suggesting that iron-sulfur clusters are mainly responsible for the NO-mediated formation of protein-bound DNICs in cells. Furthermore, depletion of “chelatable iron pool” in the wild-type E. coli cells effectively removes iron-sulfur clusters from proteins and concomitantly diminishes the NO-mediated formation of protein-bound DNICs, indicating that iron-sulfur clusters in proteins constitute at least part of “chelatable iron pool” in cells. PMID:21420489

  14. Protein-bound P-cresol inhibits human umbilical vein endothelial cell proliferation by inducing cell cycle arrest at G0/G1

    PubMed Central

    Li, Li; Li, Jing; Li, Xun; Yuan, Fa-Huan

    2017-01-01

    P-cresol is a typical protein-bound uremic toxin, which is retained in patients with renal failure. It is not known whether protein-bound P-cresol exhibits the toxicity in humans. This study aims to investigate the endothelial toxicity of protein-bound P-cresol. Cultured human umbilical vein endothelial cells (HUVEC) were treated with unbound or human serum albumin-bound (HSA, 4 g/dL), P-cresol (0, 20, 40, 80 μg/mL) for 24, 48, 72 h, respectively. Cell viability was determined by using cell counting kit-8 (CCK-8) assay. Cell apoptosis and cell cycle were assessed by using flow cytometry. The expression of cell cycle proteins in HUVEC were analyzed by using western blot and double immunofluorescent labeling assay. The results indicated that the viability of HUVEC was dose- and time-dependently inhibited by the protein-bound P-cresol (77.56% inhibition at 72 h, P<0.05) and unbound P-cresol (80.65% inhibition at 72 h, P<0.05). Most HUVECs were arrested at G0/G1 phase by both protein-bound P-cresol (79.63% inhibition at 72 h, P<0.05) and unbound P-cresol (81.27% at 72 h, P<0.05). Both protein-bound and unbound P-cresol enhanced the expression of p21Cip1 (0.62 and 0.60, both P<0.05) and suppressed the expression of cyclin D1 (0.49 and 0.53, both P<0.05) in a dose-dependent manner. In conclusion, unbound and protein-bound P-cresol inhibit the HUVEC proliferation by inducing cell cycle arrest at G0/G1 phase in a dose- and time-dependent manner, which associates with the up-regulation of p21Cip1 and down-regulation of cyclin D1. PMID:28469807

  15. Mouse mast cell secretory granules can function as intracellular ionic oscillators.

    PubMed Central

    Quesada, I; Chin, W C; Steed, J; Campos-Bedolla, P; Verdugo, P

    2001-01-01

    Fluorescent Ca2+ probes and digital photo-sectioning techniques were used to directly study the dynamics of Ca2+ in isolated mast cell granules of normal (CB/J) and beige (Bg(j)/Bg(j)) mice. The resting intraluminal free Ca2+ concentration ([Ca2+]L) is 25 +/- 4.2 microM (mean +/- SD, n = 68). Exposure to 3 microM inositol 1,4,5-trisphosphate (InsP3) induced periodic oscillations of luminal Ca2+ ([Ca2+]L) of approximately 10 microM amplitude and a period around 8-10 s. The [Ca2+]L oscillations were accompanied by a corresponding oscillatory release of [Ca2+]L to the extraluminal space. Control experiments using ruthenium red (2 microM) and thapsigargin (100 nM) ruled out artifacts derived from the eventual presence of mitochondria or endoplasmic reticulum in the isolated granule preparation. Oscillations of [Ca2+]L and Ca2+ release result from a Ca2+/K+ exchange process whereby bound Ca is displaced from the heparin polyanionic matrix by inflow of K+ into the granular lumen via an apamin-sensitive Ca2+-sensitive K+ channel (ASK(Ca)), whereas Ca2+ release takes place via an InsP3-receptor-Ca2+ (InsP3-R) channel. These results are consistent with previous observations of [Ca2+]L oscillations and release in/from the endoplasmic reticulum and mucin granules, and suggest that a highly conserved common mechanism might be responsible for [Ca2+]L oscillations and quantal periodic Ca2+ release in/from intracellular Ca2+ storage compartments. PMID:11325716

  16. Connected component masking accurately identifies the ratio of phagocytosed and cell-bound particles in individual cells by imaging flow cytometry.

    PubMed

    Fei, Chenjie; Lillico, Dustin M E; Hall, Brian; Rieger, Aja M; Stafford, James L

    2017-04-01

    Innate immune cell-mediated recognition, capture, and engulfment of large particulate targets such as bacteria is known as phagocytosis. This highly dynamic cellular process involves a series of steps including receptor-mediated target binding, phagocytic cup formation, pseudopod extension, and phagosome closure, which depend on distinct actin polymerization events. Using flow cytometry, precise determination of target locations relative to cell membranes (i.e., surface-bound vs. fully engulfed/internalized) during the phagocytic process is difficult to quantify. Here, we describe the application of new analysis features within the IDEAS® software to distinguish internalized and surface-bound particles on individual cells with a high degree of accuracy and reproducibility. Through the use of connected component masks, the accurate discrimination of surface-bound beads versus those internalized is clearly demonstrated. In addition, we were able to further analyze the ratio of beads that had been surface-bound or internalized within individual cells. This novel method of analyzing the phagocytic process provides more accurate determination of target-cell interactions that will assist in examination of the signalling events that occur during the various stages of phagocytosis. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

  17. Cell Contact–Dependent Immunosuppression by Cd4+Cd25+Regulatory T Cells Is Mediated by Cell Surface–Bound Transforming Growth Factor β

    PubMed Central

    Nakamura, Kazuhiko; Kitani, Atsushi; Strober, Warren

    2001-01-01

    CD4+CD25+ T cells have been identified as a population of immunoregulatory T cells, which mediate suppression of CD4+CD25− T cells by cell–cell contact and not secretion of suppressor cytokines. In this study, we demonstrated that CD4+CD25+ T cells do produce high levels of transforming growth factor (TGF)-β1 and interleukin (IL)-10 compared with CD4+CD25− T cells when stimulated by plate-bound anti-CD3 and soluble anti-CD28 and/or IL-2, and secretion of TGF-β1 (but not other cytokines), is further enhanced by costimulation via cytotoxic T lymphocyte–associated antigen (CTLA)-4. As in prior studies, we found that CD4+CD25+ T cells suppress proliferation of CD4+CD25− T cells; however, we observed here that such suppression is abolished by the presence of anti–TGF-β. In addition, we found that CD4+CD25+ T cells suppress B cell immunoglobulin production and that anti–TGF-β again abolishes such suppression. Finally, we found that stimulated CD4+CD25+ T cells but not CD4+CD25− T cells express high and persistent levels of TGF-β1 on the cell surface. This, plus the fact that we could find no evidence that a soluble factor mediates suppression, strongly suggests that CD4+CD25+ T cells exert immunosuppression by a cell–cell interaction involving cell surface TGF-β1. PMID:11535631

  18. Dynamics of ion transport in a bio-derived ionic transistor

    NASA Astrophysics Data System (ADS)

    Sundaresan, Vishnu Baba; Zhang, Hao; Northcutt, Robert; Salinas, Sergio

    2011-04-01

    Biological processes and electromechanical function in ionic polymers share ion transport as the fundamental processes for sensing, actuation and energy harvesting. Inspired by the similarity in protein-bound cell membranes and polypyrrole membrane (an ionic polymer), our group is developing a hybrid device that provides the template for integrating biology and electronics. The integrated device, referred to as a bio-derived ionic transistor (BIT), consists of a bilayer lipid membrane (BLM) formed on a polypyrrole membrane and has two inputs that regulates the output of the device. This proceedings article will discuss the constructional features of proposed actuator, fabrication procedure of a prototype actuator and discuss a modeling framework for analyzing the dynamics of the ionic response.

  19. Activation and inactivation of taurine efflux in hyposmotic and isosmotic swelling in cortical astrocytes: role of ionic strength and cell volume decrease.

    PubMed

    Cardin, V; Peña-Segura, C; Pasantes-Morales, H

    1999-06-15

    A decrease in intracellular ionic strength appears involved in the activation of swelling-elicited 3H-taurine efflux in cortical cultured astrocytes. Hyposmotic (50%) or isosmotic urea-induced swelling leading to a decrease of intracellular ionic strength, activated 3H-taurine efflux from a rate constant of about 0.008 min(-1) to 0.33 min(-1) (hyposmotic) and 0.59 min(-1) (urea). This efflux rate was markedly lower (maximal 0.03 min(-1)) in isosmotic swelling caused by K+ accumulation, where there is no decrease in ionic strength, or in cold (10 degrees C) hyposmotic medium (maximal 0.18 min(-1)), where swelling is reduced and consequently intracellular ionic strength is less affected. Also, astrocytes pretreated with hyperosmotic medium, which recover cell volume by ion accumulation, did not release 3H-taurine when they swelled by switching to isosmotic medium, but when volume was recovered by accumulation of urea, taurine release was restored. These results point to a key role of ionic strength in the activation of osmosensitive 3H-taurine efflux. In contrast, its inactivation was independent of the change in ionic strength but appears related to the reduction in cell volume after swelling, since despite the extent or direction of the change in ionic strength, the 3H-taurine efflux did not inactivate in isosmotic KCl-elicited swelling when cell volume did not recover nor in hyposmotic swelling when RVD was impaired by replacing NaCl in the medium by permeant osmolytes.

  20. ZnO-based dye solar cell with pure ionic-liquid electrolyte and organic sensitizer: the relevance of the dye–oxide interaction in an ionic-liquid medium.

    PubMed

    Guillén, E; Idígoras, J; Berger, T; Anta, J A; Fernández-Lorenzo, C; Alcántara, R; Navas, J; Martín-Calleja, J

    2011-01-07

    The use of non-volatile electrolytes and fully organic dyes are key issues in the development of stable dye-sensitized solar cells (DSCs). In this work we explore the performance of ZnO-based DSCs sensitized with an indoline derivative coded D149 in the presence of a pure ionic-liquid electrolyte. Commercial nanostructured zinc oxide and an electrolyte composed of iodine plus (1) pure 1-propyl-3-methyl imidazolium iodide (PMII) and (2) a blend of PMII with low-viscosity ionic liquids were employed to construct the devices. Without further additives, the fabricated devices exhibit remarkable short-circuit photocurrents and efficiencies under AM1.5 simulated sunlight (up to 10.6 mA cm−2, 2.9% efficiency, 1 sun, active area = 0.64 cm2) due to the high surface area of the ZnO film and the high absorptivity of the D149 dye. Impedance spectroscopy is used to characterize the devices. It is found that the addition of the low-viscosity ionic-liquid improves the transport features (leading to a better photocurrent) but it does not alter the recombination rate. The robustness of the dye–oxide interaction is tested by applying continuous illumination with a Xenon-lamp. It is observed that the photocurrent is reduced at a slow rate due to desorption of the D149 sensitizer in the presence of the ionic liquid. Exploration of alternative ionic-liquid compositions or modification of the ZnO surface is therefore required to make stable devices based on ZnO and fully organic dyes.

  1. Regeneration of Aplysia bag cell neurons is synergistically enhanced by substrate-bound hemolymph proteins and laminin.

    PubMed

    Hyland, Callen; Dufresne, Eric R; Dufrense, Eric R; Forscher, Paul

    2014-04-11

    We have investigated Aplysia hemolymph as a source of endogenous factors to promote regeneration of bag cell neurons. We describe a novel synergistic effect between substrate-bound hemolymph proteins and laminin. This combination increased outgrowth and branching relative to either laminin or hemolymph alone. Notably, the addition of hemolymph to laminin substrates accelerated growth cone migration rate over ten-fold. Our results indicate that the active factor is either a high molecular weight protein or protein complex and is not the respiratory protein hemocyanin. Substrate-bound factor(s) from central nervous system-conditioned media also had a synergistic effect with laminin, suggesting a possible cooperation between humoral proteins and nervous system extracellular matrix. Further molecular characterization of active factors and their cellular targets is warranted on account of the magnitude of the effects reported here and their potential relevance for nervous system repair.

  2. Regeneration of Aplysia Bag Cell Neurons is Synergistically Enhanced by Substrate-Bound Hemolymph Proteins and Laminin

    NASA Astrophysics Data System (ADS)

    Hyland, Callen; Dufrense, Eric R.; Forscher, Paul

    2014-04-01

    We have investigated Aplysia hemolymph as a source of endogenous factors to promote regeneration of bag cell neurons. We describe a novel synergistic effect between substrate-bound hemolymph proteins and laminin. This combination increased outgrowth and branching relative to either laminin or hemolymph alone. Notably, the addition of hemolymph to laminin substrates accelerated growth cone migration rate over ten-fold. Our results indicate that the active factor is either a high molecular weight protein or protein complex and is not the respiratory protein hemocyanin. Substrate-bound factor(s) from central nervous system-conditioned media also had a synergistic effect with laminin, suggesting a possible cooperation between humoral proteins and nervous system extracellular matrix. Further molecular characterization of active factors and their cellular targets is warranted on account of the magnitude of the effects reported here and their potential relevance for nervous system repair.

  3. Growth and bile tolerance of Lactobacillus brevis strains isolated from Japanese pickles in artificial digestive juices and contribution of cell-bound exopolysaccharide to cell aggregation.

    PubMed

    Suzuki, Shigenori; Honda, Hiroyuki; Suganuma, Hiroyuki; Saito, Tadao; Yajima, Nobuhiro

    2014-03-01

    Cell-bound exopolysaccharide (EPS) of the aggregable strain Lactobacillus brevis KB290 isolated from traditional Japanese pickles has been reported to protect against the effects of bile. However, there are no reports of bile tolerance mechanisms for other L. brevis strains that have aggregability. To elucidate the mechanism of bile tolerance of L. brevis KB290, we found 8 aggregable L. brevis strains out of 121 L. brevis strains isolated from traditional Japanese fermented pickles. We estimated their growth in artificial digestive juice and the amount of cell-bound EPS. We found 3 types of aggregation for these strains: filiform (<1 mm), medium floc (1-5 mm), or large floc (>5 mm). There was no significant difference in growth between nonaggregable and aggregable strains in the artificial digestive juice. The large floc strains selected from the aggregation strains showed significantly higher growth in the artificial digestive juice than nonaggregable strains. In medium and large floc strains, cell-bound EPS, mainly consisting of glucose, N-acetylglucosamine, and N-acetylmannosamine, were observed. The amount of EPS and each strain's growth index showed a positive correlation. We conclude that aggregable L. brevis strains were also protected by cell-bound EPS.

  4. Physicochemical properties of ionic and non-ionic biocompatible hydrogels in water and cell culture conditions: Relation with type of morphologies of bovine fetal fibroblasts in contact with the surfaces.

    PubMed

    Rivero, Rebeca; Alustiza, Fabrisio; Capella, Virginia; Liaudat, Cecilia; Rodriguez, Nancy; Bosch, Pablo; Barbero, Cesar; Rivarola, Claudia

    2017-07-11

    Cationic, anionic and non-ionic hydrogels having acrylamide polymer backbones were synthesized via free radical polymerization with N,N-methylenebisacrylamide (BIS) as crosslinker. The chemical structures of the hydrogels were characterized by Fourier Transform Infrared Spectroscopy (FTIR). Physicochemical properties such as swelling kinetic, maximum swelling capacity, volume phase transition temperature (VPTT) and wettability (static water contact angle) of hydrogels swollen in aqueous and cell culture medium, at room and cell culture temperatures were studied. In order to correlate the surface properties of the hydrogels and cellular adhesivity of bovine fetal fibroblasts (BFFs), cellular behaviour was analyzed by inverted fluorescence optical microscopy and atomic force microscopy (AFM). MTT assay demonstrated that the number of viable cells in contact with hydrogels does not significantly change in comparison to a control surface. Flattened and spindle-shaped cells and cell spheroids were the adopted morphologies during first days of culture on different hydrogels. Cell spheroids were easily obtained during the first 5days of culture in contact with PNIPAM-co-20%HMA (poly (N-isopropylacrylamide-co-20%N-acryloyl-tris-(hydroxymethyl)aminomethane)) hydrogel surface. After 15days of culture all hydrogels showed high adhesion and visual proliferation. According to obtained results, non-ionic and hydrophilic surfaces with moderated wettability induce the formation of BFFs cell spheroids. These hydrogel surfaces could be used in clinical and biochemical treatments at laboratory level to cell growth and will allow generating the base for future biotechnologic platform. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid

    PubMed Central

    Khanmirzaei, Mohammad Hassan; Ramesh, S.; Ramesh, K.

    2015-01-01

    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10−3 S cm−1 is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm−2, 610 mV and 69.1%, respectively. PMID:26659087

  6. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid

    NASA Astrophysics Data System (ADS)

    Khanmirzaei, Mohammad Hassan; Ramesh, S.; Ramesh, K.

    2015-12-01

    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10-3 S cm-1 is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm-2, 610 mV and 69.1%, respectively.

  7. Antigenic Properties of the Human Immunodeficiency Virus Envelope Glycoprotein Gp120 on Virions Bound to Target Cells

    PubMed Central

    Mengistu, Meron; Ray, Krishanu; Lewis, George K.; DeVico, Anthony L.

    2015-01-01

    The HIV-1 envelope glycoprotein, gp120, undergoes multiple molecular interactions and structural rearrangements during the course of host cell attachment and viral entry, which are being increasingly defined at the atomic level using isolated proteins. In comparison, antigenic markers of these dynamic changes are essentially unknown for single HIV-1 particles bound to target cells. Such markers should indicate how neutralizing and/or non-neutralizing antibodies might interdict infection by either blocking infection or sensitizing host cells for elimination by Fc-mediated effector function. Here we address this deficit by imaging fluorescently labeled CCR5-tropic HIV-1 pseudoviruses using confocal and superresolution microscopy to track the exposure of neutralizing and non-neutralizing epitopes as they appear on single HIV-1 particles bound to target cells. Epitope exposure was followed under conditions permissive or non-permissive for viral entry to delimit changes associated with virion binding from those associated with post-attachment events. We find that a previously unexpected array of gp120 epitopes is exposed rapidly upon target cell binding. This array comprises both neutralizing and non-neutralizing epitopes, the latter being hidden on free virions yet capable of serving as potent targets for Fc-mediated effector function. Under non-permissive conditions for viral entry, both neutralizing and non-neutralizing epitope exposures were relatively static over time for the majority of bound virions. Under entry-permissive conditions, epitope exposure patterns changed over time on subsets of virions that exhibited concurrent variations in virion contents. These studies reveal that bound virions are distinguished by a broad array of both neutralizing and non-neutralizing gp120 epitopes that potentially sensitize a freshly engaged target cell for destruction by Fc-mediated effector function and/or for direct neutralization at a post-binding step. The elucidation of

  8. Ionic Liquid Crystals: Versatile Materials.

    PubMed

    Goossens, Karel; Lava, Kathleen; Bielawski, Christopher W; Binnemans, Koen

    2016-04-27

    This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the "state-of-the-art" in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions.

  9. Efficient labeling in vitro with non-ionic gadolinium magnetic resonance imaging contrast agent and fluorescent transfection agent in bone marrow stromal cells of neonatal rats

    PubMed Central

    LI, YING-QIN; TANG, YING; FU, RAO; MENG, QIU-HUA; ZHOU, XUE; LING, ZE-MIN; CHENG, XIAO; TIAN, SU-WEI; WANG, GUO-JIE; LIU, XUE-GUO; ZHOU, LI-HUA

    2015-01-01

    Although studies have been undertaken on gadolinium labeling-based molecular imaging in magnetic resonance imaging (MRI), the use of non-ionic gadolinium in the tracking of stem cells remains uncommon. To investigate the efficiency in tracking of stem cells with non-ionic gadolinium as an MRI contrast agent, a rhodamine-conjugated fluorescent reagent was used to label bone marrow stromal cells (BMSCs) of neonatal rats in vitro, and MRI scanning was undertaken. The fluorescent-conjugated cell uptake reagents were able to deliver gadodiamide into BMSCs, and cell uptake was verified using flow cytometry. In addition, the labeled stem cells with paramagnetic contrast medium remained detectable by an MRI monitor for a minimum of 28 days. The present study suggested that this method can be applied efficiently and safely for the labeling and tracking of bone marrow stromal cells in neonatal rats. PMID:25816076

  10. Release of Membrane-Bound Vesicles and Inhibition of Tumor Cell Adhesion by the Peptide Neopetrosiamide A

    PubMed Central

    Austin, Pamela; Heller, Markus; Williams, David E.; McIntosh, Lawrence P.; Vogl, A. Wayne; Foster, Leonard J.; Andersen, Raymond J.; Roberge, Michel; Roskelley, Calvin D.

    2010-01-01

    Background Neopetrosiamide A (NeoA) is a 28-amino acid tricyclic peptide originally isolated from a marine sponge as a tumor cell invasion inhibitor whose mechanism of action is unknown. Methodology/Principal Findings We show that NeoA reversibly inhibits tumor cell adhesion, disassembles focal adhesions in pre-attached cells, and decreases the level of β1 integrin subunits on the cell surface. NeoA also induces the formation of dynamic, membrane-bound protrusions on the surface of treated cells and the release of membrane-bound vesicles into the culture medium. Proteomic analysis indicates that the vesicles contain EGF and transferrin receptors as well as a number of proteins involved in adhesion and migration including: β1 integrin and numerous α integrin subunits; actin and actin-binding proteins such as cofilin, moesin and myosin 1C; and membrane modulating eps15 homology domain (EHD) proteins. Surface labeling, trafficking inhibition, and real-time imaging experiments all suggest that β1 integrin-containing vesicles are released directly from NeoA-induced cell surface protrusions rather than from vesicles generated intracellularly. The biological activity of NeoA is dependent on its disulfide bond pattern and NMR spectroscopy indicates that the peptide is globular with a continuous ridge of hydrophobic groups flanked by charged amino acid residues that could facilitate a simultaneous interaction with lipids and proteins in the membrane. Conclusions/Significance NeoA is an anti-adhesive peptide that decreases cell surface integrin levels through a novel, yet to be elucidated, mechanism that involves the release of adhesion molecule-containing vesicles from the cell surface. PMID:20520768

  11. Silica nanoparticle doped organic ionic plastic crystal electrolytes for highly efficient solid-state dye-sensitized solar cells.

    PubMed

    Shi, Chengzhen; Qiu, Lihua; Chen, Xiaojian; Zhang, Haigang; Wang, Lei; Yan, Feng

    2013-02-01

    Organic ionic plastic crystal, 1-propyl-1-methylpyrrolidinium iodide (P₁₃I), which possesses a broad plastic phase from -36 to 135 °C, was doped with silica nanoparticles (SiO₂ NPs) and 1-ethyl-3-methylimidazolium iodide (EMII), for the preparation of SiO₂/EMII/P₁₃I solid-state electrolytes for dye-sensitized solar cells (DSSCs). The thermal properties of all the electrolytes, including solid-solid phase transitions and melting temperatures, were investigated by differential scanning calorimetry (DSC). The effect of silica particles on the ionic conductivity, diffusion of I⁻/I₃⁻ redox couple in electrolytes, and photovoltaic performance for solid-state DSSCs were investigated. The fabricated solid-state DSSCs yielded a high power conversion efficiency of 5.25% under simulated air mass 1.5 solar spectrum illuminations at 50 mW cm⁻². Furthermore, the DSSCs based on SiO₂/EMII/P₁₃I solid-state electrolytes show good stability after an accelerating aging test, demonstrating potential practical applications.

  12. Fast ionic conduction in tetravalent metal pyrophosphate-alkali carbonate composites: New potential electrolytes for intermediate-temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Singh, Bhupendra; Bhardwaj, Aman; Gautam, Sandeep K.; Kumar, Devendra; Parkash, Om; Kim, In-Ho; Song, Sun-Ju

    2017-03-01

    Here we present a report on synthesis and characterization of tetravalent metal pyrophosphate (TMP) and alkali carbonate (A2CO3; A = Li and/or Na) composites. The TMP-carbonate composites are prepared by mixing indium-doped tin pyrophosphate or yttrium-doped zirconium pyrophosphate with Li2CO3 or an eutectic mixture of Li2CO3-Na2CO3 in different wt.% ratios. The phase composition, microstructure and electrical conductivity of the sintered specimen are analyzed. In addition, the effect of different TMP and A2CO3 phases is investigated. A maximum ionic conductivity of 5.5 × 10-2 S cm-1 at 630 °C is observed in this study with a Sn0.9In0.1P2O7-Li2CO3 composite. Based on the literature data, TMP-carbonate composites can be considered to be primarily a proton and oxygen-ion co-ionic conductor and, therefore, have strong potential as electrolytes in fuel cells in 500-700 °C range.

  13. Recrystallized quinolinium ionic liquids for electrochemical analysis

    NASA Astrophysics Data System (ADS)

    Selvaraj, Gowri; Wilfred, Cecilia Devi; Eang, Neo Kian

    2016-11-01

    Ionic liquids have received a lot of attention due to their unique properties. In this work the prospect of quinolinium based ionic liquids as electrolyte for dye sensitised solar cell were tested using cyclic voltammetry. The results have shown electron transfer in the ionic liquid without undergoing any permanent chemical changes. Prior to testing, the ionic liquids were purified through recrystallization as electrochemical properties of ionic liquids are highly dependent on the purity of the ionic liquids. This results have shone new light for this work.

  14. Bisphosphonates Inhibit Stellate Cell Activity and Enhance Antitumor Effects of Nanoparticle Albumin Bound-Paclitaxel in Pancreatic Ductal Adenocarcinoma

    PubMed Central

    Gonzalez-Villasana, Vianey; Rodriguez-Aguayo, Cristian; Arumugam, Thiruvengadam; Cruz-Monserrate, Zobeida; Fuentes-Mattei, Enrique; Deng, Defeng; Hwang, Rosa F.; Wang, Huamin; Ivan, Cristina; Garza, Raul Joshua; Cohen, Evan; Gao, Hui; Armaiz-Pena, Guillermo N.; Monroig-Bosque, Paloma del C.; Philip, Bincy; Rashed, Mohammed H.; Aslan, Burcu; Erdogan, Mumin Alper; Gutierrez-Puente, Yolanda; Ozpolat, Bulent; Reuben, James M.; Sood, Anil K.; Logsdon, Craig; Lopez-Berestein, Gabriel

    2014-01-01

    Pancreatic stellate cells (PSCs) have been recognized as the principal cells responsible for the production of fibrosis in PDAC. Recently PSCs have been noted to share characteristics with cells of monocyte-macrophage lineage (MML cells). Thus, we tested whether PSCs could be targeted with the nitrogen-containing bisphosphonates (NBPs) [pamidronate (Pam) or zoledronic acid (ZA)], which are potent MML cell inhibitors. In addition, we tested NBPs treatment combination with nanoparticle albumin-bound paclitaxel (nab-paclitaxel) to enhance antitumor activity. In vitro we observed that PSCs possess α-naphthyl butyrate esterase (ANBE) enzyme activity, a specific marker of MML cells. Moreover NBPs inhibited PSCs proliferation, activation, release of macrophage chemoattractant protein-1 (MCP-1) and type I collagen expression. NBPs also induced PSC apoptosis and cell cycle arrest in the G1 phase. In vivo, NBPs inactivated PSCs; reduced fibrosis; inhibited tumor volume, tumor weight, peritoneal dissemination, angiogenesis, and cell proliferation; and increased apoptosis in an orthotopic murine model of PDAC. These in vivo antitumor effects were enhanced when NBPs were combined with nab-paclitaxel but not gemcitabine (Gem). Our study suggests that targeting PSCs and tumor cells with NBPs in combination with nab-paclitaxel may be a novel therapeutic approach to PDAC. PMID:25193509

  15. Bisphosphonates inhibit stellate cell activity and enhance antitumor effects of nanoparticle albumin-bound paclitaxel in pancreatic ductal adenocarcinoma.

    PubMed

    Gonzalez-Villasana, Vianey; Rodriguez-Aguayo, Cristian; Arumugam, Thiruvengadam; Cruz-Monserrate, Zobeida; Fuentes-Mattei, Enrique; Deng, Defeng; Hwang, Rosa F; Wang, Huamin; Ivan, Cristina; Garza, Raul Joshua; Cohen, Evan; Gao, Hui; Armaiz-Pena, Guillermo N; Del C Monroig-Bosque, Paloma; Philip, Bincy; Rashed, Mohammed H; Aslan, Burcu; Erdogan, Mumin Alper; Gutierrez-Puente, Yolanda; Ozpolat, Bulent; Reuben, James M; Sood, Anil K; Logsdon, Craig; Lopez-Berestein, Gabriel

    2014-11-01

    Pancreatic stellate cells (PSC) have been recognized as the principal cells responsible for the production of fibrosis in pancreatic ductal adenocarcinoma (PDAC). Recently, PSCs have been noted to share characteristics with cells of monocyte-macrophage lineage (MML cells). Thus, we tested whether PSCs could be targeted with the nitrogen-containing bisphosphonates (NBP; pamidronate or zoledronic acid), which are potent MML cell inhibitors. In addition, we tested NBPs treatment combination with nanoparticle albumin-bound paclitaxel (nab-paclitaxel) to enhance antitumor activity. In vitro, we observed that PSCs possess α-naphthyl butyrate esterase (ANBE) enzyme activity, a specific marker of MML cells. Moreover, NBPs inhibited PSCs proliferation, activation, release of macrophage chemoattractant protein-1 (MCP-1), and type I collagen expression. NBPs also induced PSCs apoptosis and cell-cycle arrest in the G1 phase. In vivo, NBPs inactivated PSCs; reduced fibrosis; inhibited tumor volume, tumor weight, peritoneal dissemination, angiogenesis, and cell proliferation; and increased apoptosis in an orthotopic murine model of PDAC. These in vivo antitumor effects were enhanced when NBPs were combined with nab-paclitaxel but not gemcitabine. Our study suggests that targeting PSCs and tumor cells with NBPs in combination with nab-paclitaxel may be a novel therapeutic approach to PDAC. ©2014 American Association for Cancer Research.

  16. Human Renal Normal, Tumoral, and Cancer Stem Cells Express Membrane-Bound Interleukin-15 Isoforms Displaying Different Functions1

    PubMed Central

    Azzi, Sandy; Gallerne, Cindy; Romei, Cristina; Le Coz, Vincent; Gangemi, Rosaria; Khawam, Krystel; Devocelle, Aurore; Gu, Yanhong; Bruno, Stefania; Ferrini, Silvano; Chouaib, Salem; Eid, Pierre; Azzarone, Bruno; Giron-Michel, Julien

    2015-01-01

    Intrarenal interleukin-15 (IL-15) participates to renal pathophysiology, but the role of its different membrane-bound isoforms remains to be elucidated. In this study, we reassess the biology of membrane-bound IL-15 (mb-IL-15) isoforms by comparing primary cultures of human renal proximal tubular epithelial cells (RPTEC) to peritumoral (ptumTEC), tumoral (RCC), and cancer stem cells (CSC/CD105+). RPTEC express a 14 to 16 kDa mb-IL-15, whose existence has been assumed but never formally demonstrated and likely represents the isoform anchored at the cell membrane through the IL-15 receptor α (IL-15Rα) chain, because it is sensitive to acidic treatment and is not competent to deliver a reverse signal. By contrast, ptumTEC, RCC, and CSC express a novel N-hyperglycosylated, short-lived transmembrane mb-IL-15 (tmb-IL-15) isoform around 27 kDa, resistant to acidic shock, delivering a reverse signal in response to its soluble receptor (sIL-15Rα). This reverse signal triggers the down-regulation of the tumor suppressor gene E-cadherin in ptumTEC and RCC but not in CSC/CD105+, where it promotes survival. Indeed, through the AKT pathway, tmb-IL-15 protects CSC/CD105+ from non-programmed cell death induced by serum starvation. Finally, both mb-IL-15 and tmb-IL-15 are sensitive to metalloproteases, and the cleaved tmb-IL-15 (25 kDa) displays a powerful anti-apoptotic effect on human hematopoietic cells. Overall, our data indicate that both mb-IL-15 and tmb-IL-15 isoforms play a complex role in renal pathophysiology downregulating E-cadherin and favoring cell survival. Moreover, “apparently normal” ptumTEC cells, sharing different properties with RCC, could contribute to organize an enlarged peritumoral “preneoplastic” environment committed to favor tumor progression. PMID:26152359

  17. Towards Li(Ni0.33Mn0.33Co0.33)O2/graphite batteries with ionic liquid-based electrolytes. I. Electrodes' behavior in lithium half-cells

    NASA Astrophysics Data System (ADS)

    Simonetti, E.; Maresca, G.; Appetecchi, G. B.; Kim, G.-T.; Loeffler, N.; Passerini, S.

    2016-11-01

    Lithium cells based on NMC cathodes or graphite anodes and ionic liquid-based electrolyte mixtures are investigated. The electrode tapes, using water-soluble natural binders, as well as the ionic liquid materials, are prepared through eco-friendly routes involving H2O as the only processing solvent. The Li/NMC and Li/graphite half-cells are studied by cyclic voltammetry, impedance spectroscopy and galvanostatic cycling tests at different temperatures. The results herein reported, demonstrate the performance improvement in terms of cycling behavior and ageing resistance, granted by the ionic liquid mixtures with respect to the electrolytes reported in literature based on a single ionic liquid.

  18. A cost-effective cane molasses medium for enhanced cell-bound phytase production by Pichia anomala.

    PubMed

    Vohra, A; Satyanarayana, T

    2004-01-01

    Formulation of an inexpensive cane molasses medium for improved cell-bound phytase production by Pichia anomala. Cell-bound phytase production by Pichia anomala was compared in synthetic glucose-beef extract and cane molasses media. The yeast was cultivated in 250 ml flasks containing 50 ml of the medium, inoculated with a 12 h-old inoculum (3 x 10(6) CFU ml(-1)) and incubated at 25 degrees C for 24 h at 250 rev min(-1). Different cultural parameters were optimized in cane molasses medium in batch fermentation. The cell-bound phytase content increased significantly in cane molasses medium (176 U g(-1) dry biomass) when compared with the synthetic medium (100 U g(-1) dry biomass). In fed-batch fermentation, a marked increase in biomass (20 g l(-1)) and the phytase yield (3000 U l(-1)) were recorded in cane molasses medium. The cost of production in cane molasses medium was pound 0.006 per 1000 U, which is much lower when compared with that in synthetic medium (pound 0.25 per 1000 U). An overall 86.6% enhancement in phytase yield was attained in optimized cane molasses medium using fed-batch fermentation when compared with that in synthetic medium. Furthermore, the production in cane molasses medium is cost-effective. Phytase yield was improved in cane molasses when compared with the synthetic medium, and the cost of production was also significantly reduced. This enzyme can find application in the animal feed industry for improving the nutritional status of feed and combating environmental pollution. Copyright 2004 The Society for Applied Microbiology

  19. Synthesis of hetero ionic compounds using dialkylcarbonate quaternization

    DOEpatents

    Friesen, Cody A.; Wolfe, Derek; Johnson, Paul Bryan

    2017-09-19

    Methods of preparing hetero ionic complexes, and ionic liquids from bisulfate salts of heteroatomic compounds using dialkylcarbonates as a primary quaternizing reactant are disclosed. Also disclosed are methods of making electrochemical cells comprising the ionic liquids, and an electrochemical cell comprising an alkaline electrolyte and a hetero ionic complex additive.

  20. Involvement of caspase-12-dependent apoptotic pathway in ionic radiocontrast urografin-induced renal tubular cell injury

    SciTech Connect

    Wu, Cheng Tien; Weng, Te I.; Chen, Li Ping; Chiang, Chih Kang; Liu, Shing Hwa

    2013-01-01

    Contrast medium (CM) induces a direct toxic effect on renal tubular cells. This toxic effect subjects in the disorder of CM-induced nephropathy. Our previous work has demonstrated that CM shows to activate the endoplasmic reticulum (ER)-related adaptive unfolding protein response (UPR) activators. Glucose-regulated protein 78 (GRP78)/eukaryotic initiation factor 2α (eIF2α)-related pathways play a protective role during the urografin (an ionic CM)-induced renal tubular injury. However, the involvement of ER stress-related apoptotic signals in the urografin-induced renal tubular cell injury remains unclear. Here, we examined by the in vivo and in vitro experiments to explore whether ER stress-regulated pro-apoptotic activators participate in urografin-induced renal injury. Urografin induced renal tubular dilation, tubular cells detachment, and necrosis in the kidneys of rats. The tubular apoptosis, ER stress-related pro-apoptotic transcriptional factors, and kidney injury marker-1 (kim-1) were also conspicuously up-regulated in urografin-treated rats. Furthermore, treatment of normal rat kidney (NRK)-52E tubular cells with urografin augmented the expressions of activating transcription factor-6 (ATF-6), C/EBP homologous protein (CHOP), Bax, caspase-12, JNK, and inositol-requiring enzyme (IRE) 1 signals. Urografin-induced renal tubular cell apoptosis was not reversed by the inhibitors of ATF-6, JNK signals or CHOP siRNA transfection, but it could be partially reversed by the inhibitor of caspase-12. Taken together, the present results and our previous findings suggest that exposure of CM/urografin activates the ER stress-regulated survival- and apoptosis-related signaling pathways in renal tubular cells. Caspase-12-dependent apoptotic pathway may be partially involved in the urografin-induced nephropathy. -- Highlights: ► Ionic contrast medium-urografin induces renal tubular cell apoptosis. ► Urografin induces the ER stress-regulated survival and apoptosis

  1. Purification and characterization of soluble (cytosolic) and bound (cell wall) isoforms of invertases in barley (Hordeum vulgare) elongating stem tissue

    NASA Technical Reports Server (NTRS)

    Karuppiah, N.; Vadlamudi, B.; Kaufman, P. B.

    1989-01-01

    Three different isoforms of invertases have been detected in the developing internodes of barley (Hordeum vulgare). Based on substrate specificities, the isoforms have been identified to be invertases (beta-fructosidases EC 3.2.1.26). The soluble (cytosolic) invertase isoform can be purified to apparent homogeneity by diethylaminoethyl cellulose, Concanavalin-A Sepharose, organo-mercurial Sepharose, and Sephacryl S-300 chromatography. A bound (cell wall) invertase isoform can be released by 1 molar salt and purified further by the same procedures as above except omitting the organo-mercurial Sepharose affinity chromatography step. A third isoform of invertase, which is apparently tightly associated with the cell wall, cannot be isolated yet. The soluble and bound invertase isoforms were purified by factors of 60- and 7-fold, respectively. The native enzymes have an apparent molecular weight of 120 kilodaltons as estimated by gel filtration. They have been identified to be dimers under denaturing and nondenaturing conditions. The soluble enzyme has a pH optimum of 5.5, Km of 12 millimolar, and a Vmax of 80 micromole per minute per milligram of protein compared with cell wall isozyme which has a pH optimum of 4.5, Km of millimolar, and a Vmax of 9 micromole per minute per milligram of protein.

  2. Purification and characterization of soluble (cytosolic) and bound (cell wall) isoforms of invertases in barley (Hordeum vulgare) elongating stem tissue

    NASA Technical Reports Server (NTRS)

    Karuppiah, N.; Vadlamudi, B.; Kaufman, P. B.

    1989-01-01

    Three different isoforms of invertases have been detected in the developing internodes of barley (Hordeum vulgare). Based on substrate specificities, the isoforms have been identified to be invertases (beta-fructosidases EC 3.2.1.26). The soluble (cytosolic) invertase isoform can be purified to apparent homogeneity by diethylaminoethyl cellulose, Concanavalin-A Sepharose, organo-mercurial Sepharose, and Sephacryl S-300 chromatography. A bound (cell wall) invertase isoform can be released by 1 molar salt and purified further by the same procedures as above except omitting the organo-mercurial Sepharose affinity chromatography step. A third isoform of invertase, which is apparently tightly associated with the cell wall, cannot be isolated yet. The soluble and bound invertase isoforms were purified by factors of 60- and 7-fold, respectively. The native enzymes have an apparent molecular weight of 120 kilodaltons as estimated by gel filtration. They have been identified to be dimers under denaturing and nondenaturing conditions. The soluble enzyme has a pH optimum of 5.5, Km of 12 millimolar, and a Vmax of 80 micromole per minute per milligram of protein compared with cell wall isozyme which has a pH optimum of 4.5, Km of millimolar, and a Vmax of 9 micromole per minute per milligram of protein.

  3. Purification and characterization of soluble (cytosolic) and bound (cell wall) isoforms of invertases in barley (Hordeum vulgare) elongating stem tissue.

    PubMed

    Karuppiah, N; Vadlamudi, B; Kaufman, P B

    1989-01-01

    Three different isoforms of invertases have been detected in the developing internodes of barley (Hordeum vulgare). Based on substrate specificities, the isoforms have been identified to be invertases (beta-fructosidases EC 3.2.1.26). The soluble (cytosolic) invertase isoform can be purified to apparent homogeneity by diethylaminoethyl cellulose, Concanavalin-A Sepharose, organo-mercurial Sepharose, and Sephacryl S-300 chromatography. A bound (cell wall) invertase isoform can be released by 1 molar salt and purified further by the same procedures as above except omitting the organo-mercurial Sepharose affinity chromatography step. A third isoform of invertase, which is apparently tightly associated with the cell wall, cannot be isolated yet. The soluble and bound invertase isoforms were purified by factors of 60- and 7-fold, respectively. The native enzymes have an apparent molecular weight of 120 kilodaltons as estimated by gel filtration. They have been identified to be dimers under denaturing and nondenaturing conditions. The soluble enzyme has a pH optimum of 5.5, Km of 12 millimolar, and a Vmax of 80 micromole per minute per milligram of protein compared with cell wall isozyme which has a pH optimum of 4.5, Km of millimolar, and a Vmax of 9 micromole per minute per milligram of protein.

  4. Heat-treatment method for producing fatty acid-bound alpha-lactalbumin that induces tumor cell death.

    PubMed

    Kamijima, Tatsuro; Ohmura, Ayaka; Sato, Toshiya; Akimoto, Kaoru; Itabashi, Miki; Mizuguchi, Mineyuki; Kamiya, Masakatsu; Kikukawa, Takashi; Aizawa, Tomoyasu; Takahashi, Masayuki; Kawano, Keiichi; Demura, Makoto

    2008-11-07

    HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells), which was identified in human breast milk as an alpha-lactalbumin (LA)-oleic acid complex, kills tumor cells, selectively. Although it may have potential as a therapeutic agent against various tumor cells, only low-volume methods for its production exist. In this study, heat treatment was used to produce complexes from LAs and oleic acid using a simple method. In the case of human LA and oleic acid, heat-treated samples apparently showed much stronger activities than those treated at room temperature, with cytotoxicities equal to that of HAMLET. Furthermore, circular dichroism spectroscopy revealed that heat-treated samples lost their tertiary structure, suggesting a molten globule as oleic acid-bound LA. BLA samples also showed strong activities by heat treatment. Batch production with heat treatment can efficiently convert LAs into tumoricidal complexes.

  5. Antitumor immunity induced by tumor cells engineered to express a membrane-bound form of IL-2.

    PubMed

    Chang, Mi-Ra; Lee, Woong-Hee; Choi, Jin-Wha; Park, Sun-Ok; Paik, Sang-Gi; Kim, Young Sang

    2005-06-30

    Transduction of cytokine gene into tumor cells is a promising method of tumor therapy, but the value is limited by accompanying side effects. To focus antitumor immune response to tumor antigen-specific CTL, we developed an antitumor vaccine by transfecting modified IL-2 gene in a membrane-bound form (mbIL-2) into B16F10 melanoma cells. The mbIL-2 clone showed reduced tumorigenicity and metastatic ability, and inhibited metastasis and prolonged the survival of mice against B16F10 cells. The inhibition of B16F10 metastasis by mbIL-2 was accompanied by the increment of CD8(+) T cells. The metastasis of mbIL-2 clone was significantly increased in the CD8(+) T cell-depleted mice, but not in CD4(+) T cell depleted mice. Spleen cells immunized with the mbIL-2 clone showed higher CTL activity towards B16F10 cells than those immunized with control cells. The size of CD8(+) T cell population in the lung of mice injected with the mbIL-2 clone was markedly greater than that of mice injected with B16F10 cells, but there was no detectible change in CD4(+) and CD8(+) T cell populations of lymph nodes and spleen. These results suggest that when the mbIL-2 clone is introduced into the blood stream, it migrates mainly to lung and activates CD8(+) T cells in situ, possibly by direct priming. Such a tumor vaccine may ameliorate the toxic side effects encountered with conventional cytokine gene therapy.

  6. Generation of hydroxyl radical in isolated pea root cell wall, and the role of cell wall-bound peroxidase, Mn-SOD and phenolics in their production.

    PubMed

    Kukavica, Biljana; Mojovic, Milos; Vuccinic, Zeljko; Maksimovic, Vuk; Takahama, Umeo; Jovanovic, Sonja Veljovic

    2009-02-01

    The hydroxyl radical produced in the apoplast has been demonstrated to facilitate cell wall loosening during cell elongation. Cell wall-bound peroxidases (PODs) have been implicated in hydroxyl radical formation. For this mechanism, the apoplast or cell walls should contain the electron donors for (i) H(2)O(2) formation from dioxygen; and (ii) the POD-catalyzed reduction of H(2)O(2) to the hydroxyl radical. The aim of the work was to identify the electron donors in these reactions. In this report, hydroxyl radical (.OH) generation in the cell wall isolated from pea roots was detected in the absence of any exogenous reductants, suggesting that the plant cell wall possesses the capacity to generate .OH in situ. Distinct POD and Mn-superoxide dismutase (Mn-SOD) isoforms different from other cellular isoforms were shown by native gel electropho-resis to be preferably bound to the cell walls. Electron paramagnetic resonance (EPR) spectroscopy of cell wall isolates containing the spin-trapping reagent, 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO), was used for detection of and differentiation between .OH and the superoxide radical (O(2)(-).). The data obtained using POD inhibitors confirmed that tightly bound cell wall PODs are involved in DEPMPO/OH adduct formation. A decrease in DEPMPO/OH adduct formation in the presence of H(2)O(2) scavengers demonstrated that this hydroxyl radical was derived from H(2)O(2). During the generation of .OH, the concentration of quinhydrone structures (as detected by EPR spectroscopy) increased, suggesting that the H(2)O(2) required for the formation of .OH in isolated cell walls is produced during the reduction of O(2) by hydroxycinnamic acids. Cell wall isolates in which the proteins have been denaturated (including the endogenous POD and SOD) did not produce .OH. Addition of exogenous H(2)O(2) again induced the production of .OH, and these were shown to originate from the Fenton reaction with tightly bound metal ions

  7. Hepatic uptake of (TH)retinol bound to the serum retinol binding protein involves both parenchymal and perisinusoidal stellate cells

    SciTech Connect

    Blomhoff, R.; Norum, K.R.; Berg, T.

    1985-11-05

    We have studied the hepatic uptake of retinol bound to the circulating retinol binding protein-transthyretin complex. Labeled complex was obtained from the plasma of donor rats that were fed radioactive retinol. When labeled retinol-retinol binding protein-transthyretin complex was injected intravenously into control rats, about 45% of the administered dose was recovered in liver after 56 h. Parenchymal liver cells were responsible for an initial rapid uptake. Perisinusoidal stellate cells initially accumulated radioactivity more slowly than did the parenchymal cells, but after 16 h, these cells contained more radioactivity than the parenchymal cells. After 56 h, about 70% of the radioactivity recovered in liver was present in stellate cells. For the first 2 h after injection, most of the radioactivity in parenchymal cells was recovered as unesterified retinol. The radioactivity in the retinyl ester fraction increased after a lag period of about 2 h, and after 5 h more than 60% of the radioactivity was recovered as retinyl esters. In stellate cells, radioactivity was mostly present as retinyl esters at all time points examined. Uptake of retinol in both parenchymal cells and stellate cells was reduced considerably in vitamin A-deficient rats. Less than 5% of the injected dose of radioactivity was found in liver after 5-6 h (as compared to 25% in control rats), and the radioactivity recovered in liver from these animals was mostly in the unesterified retinol fraction. Studies with separated cells in vitro suggested that both parenchymal and stellate cells isolated from control rats were able to take up retinol from the retinol-retinol binding protein-transthyretin complex. This uptake was temperature dependent.

  8. Improved quasi-solid dye-sensitized solar cells by composite ionic liquid electrolyte including layered α-zirconium phosphate

    NASA Astrophysics Data System (ADS)

    Wang, Ning; Lin, Hong; Li, Jianbao; Li, Xin

    2006-11-01

    The authors reported a composite quasi-solid electrolyte by adding layered α-zirconium phosphate (α-ZrP) to the iodide/tri-iodide ionic liquid, 1-methyl-3-propylimidazolium dihydrophosphate, electrolyte including 4-tert-butylpyridine, which markedly improved photovoltaic properties of quasisolid dye-sensitized solar cells (DSSCs). When adding 6wt% α-ZrP, photoenergy conversion efficiency of the DSSC increases by a factor of more than 2 to 2.61%, compared to a DSSC without α-ZrP. This enhancement is primarily explained by studying dark reaction, diffusion coefficient of tri-iodide ions, exchange current density in the interface of electrolyte/Pt counterelectrode, and lifetime of electrons in mesoscopic TiO2 film.

  9. Comparative studies of HSV-1 antigens solubilised from infected cells by using non-ionic or zwitterionic detergents.

    PubMed

    Jennings, R; Erturk, M

    1990-06-01

    HSV-1 antigen preparations solubilised from Vero cells by using either the non-ionic detergent Nonidet P40 or the zwitterionic detergent Empigen BB, and purified on sucrose density gradients or over a sucrose cushion, were tested by ELISA with anti-HSV-1 glycoprotein monoclonal antibodies and by radioimmunoprecipitation (RIP) with polyclonal HSV-1 antiserum. Amongst several proteins detected in these preparations, the four major HSV-1 glycoproteins, gB, gC, gD, and gE, were found to be present. Differences between NP40 or Empigen-solubilised HSV-1 antigen preparations with respect to two of these glycoproteins, gB and gE, were detected by using a small panel of monoclonal antibodies. Comparative studies in mice showed the Empigen-solubilised HSV-1 antigen preparations elicited greater antibody responses and greater protection against lethal HSV-1 challenge infection than the NP40-solubilised preparation.

  10. Quantifying folic acid-functionalized multi-walled carbon nanotubes bound to colorectal cancer cells for improved photothermal ablation

    NASA Astrophysics Data System (ADS)

    Graham, Elizabeth G.; MacNeill, Christopher M.; Levi-Polyachenko, Nicole H.

    2013-05-01

    Peritoneal metastases of colorectal cancer are a significant challenge in the field of medicine today due to poor results of systemic chemotherapy caused by the poor diffusion of drugs across the blood-peritoneal barrier. Multi-walled carbon nanotubes (MWNTs) are a biocompatible nanomaterial that strongly absorb near-infrared light to locally heat the surrounding area. Colorectal cancer is known to overexpress folate receptor; therefore, folic acid (FA) was covalently attached to MWNTs to target colorectal cancer cells. Results from real-time polymerase chain reaction found differing expression of folate receptor-α in two colorectal cancer cell lines, RKO and HCT116, as well as a healthy epithelial cell line, HEPM. A spectrophotometric method was developed to quantify the mass of MWNTs bound to cells, and it was determined that FA-targeted MWNTs resulted in a 400-500 % greater affinity for colorectal cancer cells than untargeted MWNTs. The non-cancerous cell line, HEPM, had higher non-specific MWNT interaction and similar MWNT-FA affinity. Stimulated by 1,064 nm light, FA-functionalized MWNTs caused a 50-60 % decrease in colorectal cancer cell viability compared to a 4-10 % decrease caused by untargeted MWNTs. Our results indicate that FA-targeted MWNTs may increase the therapeutic index of MWNT-induced photothermal therapy.

  11. The effect of progesterone and 17-β estradiol on membrane-bound HLA-G in adipose derived stem cells

    PubMed Central

    Moslehi, Akram; Hashemi-beni, Batool; Moslehi, Azam; Akbari, Maryam Ali

    2016-01-01

    Membrane-bound HLA-G (mHLA-G) discovery on adipose derived stem cells (ADSCs) as a tolerogenic and immunosuppressive molecule was very important. Many documents have shown that HLA-G expression can be controlled via some hormones such as progesterone (P4) and estradiol (E2). Therefore, this study was designed to evaluate progesterone and estradiol effects on mHLA-G in ADSCs at restricted and combination concentrations. Three independent cell lines were cultured in complete free phenol red DMEM and subcultured to achieve suffi cient cells. These cells were treated with P4, E2 and P4 plus E2 at physiologic and pregnancy concentrations for 3 days in cell culture conditions. The HLA-G positive ADSCs was measured via monoclonal anti HLA-G-FITC/MEMG-09 by means of flow cytometry in nine groups. Data were analyzed by one way ANOVA and Tukey's post hoc tests. There were no signifi cant values of the mean percentage of HLA-G positive cells in E2-treated and the combination of P4 plus E2-treated ADSCs compared to control cells (p value>0.05) but P4 had a signifi cant increase on mHLA-G in ADSCs (p value<0.05). High P4 concentration increased mHLA-G but E2 and the combination of P4 plus E2 could not change mHLA-G on ADSCs. PMID:27382350

  12. The effect of progesterone and 17-β estradiol on membrane-bound HLA-G in adipose derived stem cells.

    PubMed

    Moslehi, Akram; Hashemi-Beni, Batool; Moslehi, Azam; Akbari, Maryam Ali; Adib, Minoo

    2016-07-01

    Membrane-bound HLA-G (mHLA-G) discovery on adipose derived stem cells (ADSCs) as a tolerogenic and immunosuppressive molecule was very important. Many documents have shown that HLA-G expression can be controlled via some hormones such as progesterone (P4) and estradiol (E2). Therefore, this study was designed to evaluate progesterone and estradiol effects on mHLA-G in ADSCs at restricted and combination concentrations. Three independent cell lines were cultured in complete free phenol red DMEM and subcultured to achieve suffi cient cells. These cells were treated with P4, E2 and P4 plus E2 at physiologic and pregnancy concentrations for 3 days in cell culture conditions. The HLA-G positive ADSCs was measured via monoclonal anti HLA-G-FITC/MEMG-09 by means of flow cytometry in nine groups. Data were analyzed by one way ANOVA and Tukey's post hoc tests. There were no signifi cant values of the mean percentage of HLA-G positive cells in E2-treated and the combination of P4 plus E2-treated ADSCs compared to control cells (p value>0.05) but P4 had a signifi cant increase on mHLA-G in ADSCs (p value<0.05). High P4 concentration increased mHLA-G but E2 and the combination of P4 plus E2 could not change mHLA-G on ADSCs.

  13. A Quantitative Method for Comparing the Brightness of Antibody-dye Reagents and Estimating Antibodies Bound per Cell.

    PubMed

    Kantor, Aaron B; Moore, Wayne A; Meehan, Stephen; Parks, David R

    2016-07-01

    We present a quantitative method for comparing the brightness of antibody-dye reagents and estimating antibodies bound per cell. The method is based on complementary binding of test and fill reagents to antibody capture microspheres. Several aliquots of antibody capture beads are stained with varying amounts of the test conjugate. The remaining binding sites on the beads are then filled with a second conjugate containing a different fluorophore. Finally, the fluorescence of the test conjugate compared to the fill conjugate is used to measure the relative brightness of the test conjugate. The fundamental assumption of the test-fill method is that if it takes X molecules of one test antibody to lower the fill signal by Y units, it will take the same X molecules of any other test antibody to give the same effect. We apply a quadratic fit to evaluate the test-fill signal relationship across different amounts of test reagent. If the fit is close to linear, we consider the test reagent to be suitable for quantitative evaluation of antibody binding. To calibrate the antibodies bound per bead, a PE conjugate with 1 PE molecule per antibody is used as a test reagent and the fluorescence scale is calibrated with Quantibrite PE beads. When the fluorescence per antibody molecule has been determined for a particular conjugate, that conjugate can be used for measurement of antibodies bound per cell. This provides comparisons of the brightness of different conjugates when conducted on an instrument whose statistical photoelectron (Spe) scales are known. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.

  14. Microcontact printing of substrate-bound protein patterns for cell and tissue culture.

    PubMed

    Fritz, Martin; Bastmeyer, Martin

    2013-01-01

    Patterned distributions of signalling molecules play fundamental roles during embryonic development. Several attempts have been made to reproduce these patterns in vitro. In order to study substrate-bound or membrane proteins, microcontact printing (μCP) is a suitable method for tethering molecules on various surfaces. Here, we describe three μCP variants to produce patterns down to feature sizes of about 300 nm, which are highly variable with respect to shape, protein spacing, and density. Briefly, the desired pattern is etched into a silicon master, which is then used as a master for the printing process. Each variant offers certain advantages and the method of choice depends on the desired protein and the biological question.

  15. Inhibition of cadmium ion uptake in rice (Oryza sativa) cells by a wall-bound form of silicon.

    PubMed

    Liu, Jian; Ma, Jie; He, Congwu; Li, Xiuli; Zhang, Wenjun; Xu, Fangsen; Lin, Yongjun; Wang, Lijun

    2013-11-01

    The stresses acting on plants that are alleviated by silicon (Si) range from biotic to abiotic stresses, such as heavy metal toxicity. However, the mechanism of stress alleviation by Si at the single-cell level is poorly understood. We cultivated suspended rice (Oryza sativa) cells and protoplasts and investigated them using a combination of plant nutritional and physical techniques including inductively coupled plasma mass spectrometry (ICP-MS), the scanning ion-selective electrode technique (SIET) and X-ray photoelectron spectroscopy (XPS). We found that most Si accumulated in the cell walls in a wall-bound organosilicon compound. Total cadmium (Cd) concentrations in protoplasts from Si-accumulating (+Si) cells were significantly reduced at moderate concentrations of Cd in the culture medium compared with those from Si-limiting (-Si) cells. In situ measurement of cellular fluxes of the cadmium ion (Cd(2+) ) in suspension cells and root cells of rice exposed to Cd(2+) and/or Si treatments showed that +Si cells significantly inhibited the net Cd(2+) influx, compared with that in -Si cells. Furthermore, a net negative charge (charge density) within the +Si cell walls could be neutralized by an increase in the Cd(2+) concentration in the measuring solution. A mechanism of co-deposition of Si and Cd in the cell walls via a [Si-wall matrix]Cd co-complexation may explain the inhibition of Cd ion uptake, and may offer a plausible explanation for the in vivo detoxification of Cd in rice. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  16. Toward Higher Energy Conversion Efficiency for Solid Polymer Electrolyte Dye-Sensitized Solar Cells: Ionic Conductivity and TiO2 Pore-Filling.

    PubMed

    Song, Donghoon; Cho, Woohyung; Lee, Jung Hyun; Kang, Yong Soo

    2014-04-03

    Even though the solid polymer electrolyte has many intrinsic advantages over the liquid electrolyte, its ionic conductivity and mesopore-filling are much poorer than those of the liquid electrolyte, limiting its practical application to electrochemical devices such as dye-sensitized solar cells (DSCs). Two major shortcomings associated with utilizing solid polymer electrolytes in DSCs are first discussed, low ionic conductivity and poor pore-filling in mesoporous photoanodes for DSCs. In addition, future directions for the successful utilization of solid polymer electrolytes toward improving the performance of DSCs are proposed. For instance, the facilitated mass-transport concept could be applied to increase the ionic conductivity. Modified biphasic and triple-phasic structures for the photoanode are suggested to take advantage of both the liquid- and solid-state properties of electrolytes.

  17. Generation and characterization of tabalumab, a human monoclonal antibody that neutralizes both soluble and membrane-bound B-cell activating factor

    PubMed Central

    Manetta, Joseph; Bina, Holly; Ryan, Paul; Fox, Niles; Witcher, Derrick R; Kikly, Kristine

    2014-01-01

    B-cell activating factor (BAFF) is a B-cell survival factor with a key role in B-cell homeostasis and tolerance. Dysregulated BAFF expression may contribute to autoimmune diseases or B-cell malignancies via effects on abnormal B-lymphocyte activation, proliferation, survival, and immunoglobulin secretion. Monoclonal antibodies were generated against human BAFF, characterized for species specificity and affinity, and screened for the ability to neutralize both membrane-bound and soluble BAFF. In addition, studies were undertaken to determine the relative potency of membrane-bound and soluble BAFF. Tabalumab has a high affinity for human, cynomolgus monkey, and rabbit BAFF. No binding to mouse BAFF was detected. Tabalumab was able to neutralize soluble human, cynomolgus monkey, or rabbit BAFF with equal potency. Our data demonstrate that membrane-bound BAFF can be a more potent stimulus for B-cells than soluble BAFF, and tabalumab also neutralized membrane-bound BAFF. Tabalumab prevented BAFF from binding to BAFF receptors and demonstrated pharmacodynamic effects in human BAFF transgenic mice. Tabalumab is a high-affinity human antibody with neutralizing activity against membrane-bound and soluble BAFF. Given our findings that membrane-bound BAFF can have greater in vitro potency than soluble BAFF, neutralization of both forms of BAFF is likely to be important for optimal therapeutic effect. PMID:25258549

  18. Cycling performance and thermal stability of lithium polymer cells assembled with ionic liquid-containing gel polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Yun, Ye Sun; Kim, Jin Hee; Lee, Sang-Young; Shim, Eun-Gi; Kim, Dong-Won

    Gel polymer electrolytes containing 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and a small amount of additive (vinylene carbonate, fluoroethylene carbonate, and ethylene carbonate) are prepared, and their electrochemical properties are investigated. The cathodic limit of the gel polymer electrolytes can be extended to 0 V vs. Li by the formation of a protective solid electrolyte interphase on the electrode surface. Using these gel polymer electrolytes, lithium metal polymer cells composed of a lithium anode and a LiNi 1/3Co 1/3Mn 1/3O 2 cathode are assembled, and their cycling performances are evaluated at room temperature. The cells show good cycling performance, comparable to that of a cell assembled with gel polymer electrolyte containing standard liquid electrolyte (1.0 M LiPF 6 in ethylene carbonate/diethylene carbonate). Flammability tests and differential scanning calorimetry studies show that the presence of the ionic liquid in the gel polymer electrolyte considerably improves the safety and thermal stability of the cells.

  19. A Strategy to Produce High Efficiency, High Stability Perovskite Solar Cells Using Functionalized Ionic Liquid-Dopants.

    PubMed

    Zhang, Yi; Fei, Zhaofu; Gao, Peng; Lee, Yonghui; Tirani, Farzaneh Fadaei; Scopelliti, Rosario; Feng, Yaqing; Dyson, Paul J; Nazeeruddin, Mohammad Khaja

    2017-09-01

    Functionalized imidazolium iodide salts (ionic liquids) modified with CH2 CHCH2 , CH2 CCH, or CH2 CN groups are applied as dopants in the synthesis of CH3 NH3 PbI3 -type perovskites together with a fumigation step. Notably, a solar cell device prepared from the perovskite film doped with the salt containing the CH2 CHCH2 side-chain has a power conversion efficiency of 19.21%, which is the highest efficiency reported for perovskite solar cells involving a fumigation step. However, doping with the imidazolium salts with the CH2 CCH and CH2 CN groups result in perovskite layers that lead to solar cell devices with similar or lower power conversion efficiencies than the dopant-free cell. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Structure of the Human Activating Natural Cytotoxicity Receptor NKp30 Bound to its Tumor Cell Ligand B7-H6

    SciTech Connect

    Y Li; Q Wang; R Mariuzza

    2011-12-31

    Natural killer (NK) cells are lymphocytes of the innate immune system that participate in the elimination of tumor cells. In humans, the activating natural cytotoxicity receptors (NCRs) NKp30, NKp44, and NKp46 play a major role in NK cell-mediated tumor cell lysis. NKp30 recognizes B7-H6, a member of the B7 family which is expressed on tumor, but not healthy, cells. To understand the basis for tumor surveillance by NCRs, we determined the structure of NKp30, a member of the CD28 family which includes CTLA-4 and PD-1, in complex with B7-H6. The overall organization of the NKp30-B7-H6-activating complex differs considerably from those of the CTLA-4-B7 and PD-1-PD-L T cell inhibitory complexes. Whereas CTLA-4 and PD-1 use only the front {beta}-sheet of their Ig-like domain to bind ligands, NKp30 uses both front and back {beta}-sheets, resulting in engagement of B7-H6 via the side, as well as face, of the {beta}-sandwich. Moreover, B7-H6 contacts NKp30 through the complementarity-determining region (CDR) - like loops of its V-like domain in an antibody-like interaction that is not observed for B7 or PD-L. This first structure of an NCR bound to ligand provides a template for designing molecules to stimulate NKp30-mediated cytolytic activity for tumor immunotherapy.

  1. Zwitterionic Ligands Bound to CdSe/ZnS Quantum Dots Prevent Adhesion to Mammalian Cells

    PubMed Central

    Landis, Ryan F.; Tang, Rui; Hou, Singyuk; Yazdani, Mahdieh; Lee, Yiwei; Rotello, Vincent M.

    2015-01-01

    Zwitterionic materials are useful tools in material science and biology as they provide high water solubility while preventing non-specific interactions. Quantum dots (QDs) functionalized with zwitterionic and quaternary ammonium ligands were synthesized to investigate their interactions with the outer membrane of HeLa cells. Quaternary ammonium functionalized quantum dots adhered strongly to the cell surface while zwitterionic QDs had no cell adhesion. These results demonstrate that future non-interacting nanoparticles based on this design are possible. PMID:26929589

  2. Identification of protein-bound oligosaccharides on the surface of growth cones that bind to muscle cells.

    PubMed

    Ambron, R T; Protic, J; Den, H; Gabel, C A

    1989-09-01

    In the accompanying paper (Gabel, Den, and Ambron, in press) it was shown that eight populations of glycopeptides are synthesized by single neurons of Aplysia californica. To see which glycopeptides might mediate interactions with target cells, we first identified glycopeptides that are transported selectively to synapses and growth cones. The giant neuron R2 was injected intrasomatically with 3H-glucosamine. Twenty-four hours later, 3H-glycopeptides in the axon and cell body were isolated and resolved by serial lectin affinity chromatography. Of the eight populations, the biantennary-type glycopeptides (GPbi) and those that bind to WGA (GPwga) were preferentially associated with rapidly transported glycoproteins. In contrast, the glycopeptide that consists of N-acetylglucosamine O-linked to ser/thr was mostly retained in the cell body. GPbi and GPwga were also preferentially transported to growth cones. Analyses of RUQ cells, exposed to 3H-glucosamine in vitro for 36 h showed an enrichment of GPbi and GPwga at the growth cone relative to the cell body. The disposition of the various glycopeptides in growing neurons was also examined using FITC lectins. FITC-coupled WGA, Vicia vellosa, and lentil lectin showed extensive staining of the cell body, but only WGA stained the growth cones. To investigate if GPwga interacts specifically with target cells, these glycopeptides were isolated from the neurons of 180 abdominal ganglia. GPwga, other Aplysia glycopeptides, and glycopeptides prepared from ovalbumin were coupled separately to fluorescent spheres. The spheres were then added to muscle cells isolated from the auricle of the heart, which is innervated by many neurons from the ganglion. While spheres coupled to GPwga bound to the muscle cell surface, the other glycopeptides did not. These results indicate that glycopeptides class GPwga, found among rapidly transported glycoproteins and on the growth cone surface, is able to bind to muscle cells and may therefore play

  3. Surface-Bound Molecular Gradients for the High-Throughput Screening of Cell Responses

    PubMed Central

    Lagunas, Anna; Martínez, Elena; Samitier, Josep

    2015-01-01

    Chemical gradient surfaces are described as surfaces with a gradually varying composition along their length. Continuous chemical gradients have recently been proposed as an alternative to discrete microarrays for the high-throughput screening of the effects of ligand concentration in cells. Here, we review some of the most recent examples in which gradients have been used to evaluate the effect of a varying ligand concentration in cell adhesion, morphology, growth, and differentiation of cells, including some of our recent findings. They show the importance of the organization of ligands at the nanoscale, which is highlighted by abrupt changes in cell behavior at critical concentration thresholds. PMID:26380260

  4. Lactobacillus plantarum 299v surface-bound GAPDH: a new insight into enzyme cell walls location.

    PubMed

    Saad, N; Urdaci, M; Vignoles, C; Chaignepain, S; Tallon, R; Schmitter, J M; Bressollier, P

    2009-12-01

    The aim of this study was to provide new insight into the mechanism whereby the housekeeping enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) locates to cell walls of Lactobacillus plantarum 299v. After purification, cytosolic and cell wall GAPDH (cw-GAPDH) forms were characterized and shown to be identical homotetrameric active enzymes. GAPDH concentration on cell walls was growth-time dependent. Free GAPDH was not observed on the culture supernatant at any time during growth, and provoked cell lysis was not concomitant with any reassociation of GAPDH onto the cell surface. Hence, with the possibility of cw-GAPDH resulting from autolysis being unlikely, entrapment of intracellular GAPDH on the cell wall after a passive efflux through altered plasma membrane was investigated. Flow cytometry was used to assess L. plantarum 299v membrane permeabilization after labeling with propidium iodide (PI). By combining PI uptake and cw-GAPDH activity measurements, we demonstrate here that the increase in cw-GAPDH concentration from the early exponential phase to the late stationary phase is closely related to an increase in plasma membrane permeability during growth. Moreover, we observed that increases in both plasma membrane permeability and cw-GAPDH activity were delayed when glucose was added during L. plantarum 299v growth. Using a double labeling of L. plantarum 299v cells with anti-GAPDH antibodies and propidium iodide, we established unambiguously that cells with impaired membrane manifest five times more cw-GAPDH than unaltered cells. Our results show that plasma membrane permeability appears to be closely related to the efflux of GAPDH on the bacterial cell surface, offering new insight into the understanding of the cell wall location of this enzyme.

  5. Cell Division Induces and Switches Coherent Angular Motion within Bounded Cellular Collectives.

    PubMed

    Siedlik, Michael J; Manivannan, Sriram; Kevrekidis, Ioannis G; Nelson, Celeste M

    2017-06-06

    Collective cell migration underlies many biological processes, including embryonic development, wound healing, and cancer progression. In the embryo, cells have been observed to move collectively in vortices using a mode of collective migration known as coherent angular motion (CAM). To determine how CAM arises within a population and changes over time, here, we study the motion of mammary epithelial cells within engineered monolayers, in which the cells move collectively about a central axis in the tissue. Using quantitative image analysis, we find that CAM is significantly reduced when mitosis is suppressed. Particle-based simulations recreate the observed trends, suggesting that cell divisions drive the robust emergence of CAM and facilitate switches in the direction of collective rotation. Our simulations predict that the location of a dividing cell, rather than the orientation of the division axis, facilitates the onset of this motion. These predictions agree with experimental observations, thereby providing, to our knowledge, new insight into how cell divisions influence CAM within a tissue. Overall, these findings highlight the dynamic nature of CAM and suggest that regulating cell division is crucial for tuning emergent collective migratory behaviors, such as vortical motions observed in vivo. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Cell death and growth arrest in response to photodynamic therapy with membrane-bound photosensitizers.

    PubMed

    Piette, Jacques; Volanti, Cédric; Vantieghem, Annelies; Matroule, Jean-Yves; Habraken, Yvette; Agostinis, Patrizia

    2003-10-15

    Photodynamic therapy (PDT) is a treatment for cancer and for certain benign conditions that is based on the use of a photosensitizer and light to produce reactive oxygen species in cells. Many of the photosensitizers currently used in PDT localize in different cell compartments such as mitochondria, lysosomes, endoplasmic reticulum and generate cell death by triggering necrosis and/or apoptosis. Efficient cell death is observed when light, oxygen and the photosensitizer are not limiting ("high dose PDT"). When one of these components is limiting ("low dose PDT"), most of the cells do not immediately undergo apoptosis or necrosis but are growth arrested with several transduction pathways activated. This commentary will review the mechanism of apoptosis and growth arrest mediated by two important PDT agents, i.e. pyropheophorbide and hypericin.

  7. Vascular endothelial growth factor-bound stents: application of in situ capture technology of circulating endothelial progenitor cells in porcine coronary model.

    PubMed

    Takabatake, Shu; Hayashi, Kenshi; Nakanishi, Chiaki; Hao, Hiroyuki; Sakata, Kenji; Kawashiri, Masa-Aki; Matsuda, Takehisa; Yamagishi, Masakazu

    2014-02-01

    We evaluated the in vivo performance of a newly devised vascular endothelial growth factor (VEGF)-bound stent in a porcine coronary model. An anti-CD34 antibody-bound stent, which captures endothelial progenitor cells (EPCs) to accelerate tissue formation, did not reduce intimal hyperplasia. By targeting the VEGF receptor, which is expressed on endothelial-lineage cells, we developed VEGF-bound stents that may enable selective capture of EPCs followed by rapid endothelialization. Metallic stents were first coated with poly-(ethylene-co-vinyl alcohol), and then chemically bound with either VEGF or anti-CD34 antibody. These stents were placed in porcine coronary arteries for up to 14 days. Stent surface was evaluated by immunohistochemistry and by scanning electron microscope (SEM). After 2-day stenting with VEGF-bound stents, small populations of KDR (VEGF receptor-2)-positive cells adhered to the stent struts. After 7- and 14-day stenting, struts were fully covered with newly regenerated tissue. SEM images showed that the uniform tissue formed on struts was morphologically similar to native endothelium and was continuously connected with adjacent native endothelium. On the other hand, for the anti-CD34 antibody-bound stents, stent struts were rapidly covered by newly generated tissue that consisted of multicellular aggregates. Compared with anti-CD34 antibody-bound stents, VEGF-bound stents provide highly selective capture of EPCs, followed by rapid formation of intact endothelium tissue at an early period of stenting. These results suggest that VEGF-bound stents could represent a promising therapeutic option for cardiovascular stenting, although further long-term follow-up experiment with double-blinded fashion is needed prior to clinical application. © 2014, Wiley Periodicals, Inc.

  8. Enhanced performance of PbS-sensitized solar cells via controlled successive ionic-layer adsorption and reaction.

    PubMed

    Abbas, Muhammad A; Basit, Muhammad A; Park, Tae Joo; Bang, Jin Ho

    2015-04-21

    Despite the potential of PbS quantum dots (QDs) as sensitizers for quantum-dot-sensitized solar cells (QDSSCs), achieving a high photocurrent density over 30 mA cm(-2) remains a challenging task in PbS-sensitized solar cells. In contrast to previous attempts, where Hg(2+)-doping or multi-step post-treatment is necessary, we are capable of achieving a high photocurrent exceeding 30 mA cm(-2) simply by manipulating the successive ionic layer adsorption and reaction (SILAR) method. We show that controlling temperature at which SILAR is performed is critical to obtain a higher and more uniform coverage of PbS QDs over a mesoporous TiO2 film. The deposition of a CdS inter-layer between TiO2 and PbS is found to be an effective means of ensuring high photocurrent and stability. Not only does this modification improve the light absorption capability of the photoanode, but it also has a significant effect on charge recombination and electron injection efficiency at the PbS/TiO2 interface according to our in-depth study using electrochemical impedance spectroscopy (EIS). The implication of subtle changes in the interfacial events via modified SILAR conditions for PbS-sensitized solar cells is discussed.

  9. A novel electrolysis cell for CO2 reduction to CO in ionic liquid/organic solvent electrolyte

    NASA Astrophysics Data System (ADS)

    Shi, Jin; Shi, Feng; Song, Ning; Liu, Jian-Xiong; Yang, Xi-Kun; Jia, You-Jian; Xiao, Zheng-Wei; Du, Ping

    2014-08-01

    A novel electrolysis cell has been developed for CO2 reduction to CO in an ionic liquid/organic solvent electrolyte. The electrolysis cell is separated into two compartments by an ion-exchange membrane (Nafion117). The cathode compartment is filled with a CO2 saturated 1-butyl-3-methyl-imidazolium trifluoromethanesulfonates ([Bmim][CF3SO3])/propylene carbonate (PC) solution. The anode compartment is filled with a 0.1 M H2SO4 aqueous solution. A Ag foil and a graphite rod are used as the cathode and the anode respectively. In this electrolysis cell, CO2 reduction can be carried out in the nonaqueous electrolyte, and H2O oxidation can be carried out in the aqueous solution. Thus CO can be produced from CO2 and H2O. Owing to the high solubility of CO2 in the nonaqueous electrolyte, the Faradaic efficiency of CO formation is high, reached 90.1% at -1.72 V (vs Pt wire). After 3 h electrolysis, no poisonous species are observed on the cathode. The Ag electrode exhibits a high electrocatalytic activity for CO2 reduction to CO.

  10. Mannosylated Lipid Nano-emulsions Loaded with Lycorine-oleic Acid Ionic Complex for Tumor Cell-specific Delivery

    PubMed Central

    Guo, Yangming; Liu, Xing; Sun, Xun; Zhang, Qiang; Gong, Tao; Zhang, Zhirong

    2012-01-01

    This study was to prepare a mannosylated lycorine lipid nano-emulsion formulation (M-LYC-OA-LNEs) for the aim of achieving tumor targeting delivery of lycorine (LYC) . The low lipophilicity of LYC made it hard to be dispersed into lipid nano-emulsions (LNEs). In order to increase its lipophilicity, lycorine-oleic acid ionic complex (LYC-OA) was made. M-LYC-OA-LNEs and uncoated lycorine-oleic acid loaded lipid nano-emulsions (LYC-OA-LNEs) were prepared by solvent injection method and characterized by transmission electron microscopy (TEM), particle size, polydispersity index, zeta-potential and entrapment efficiency analysis. The in vitro cellular uptake and growth inhibition activity studies were performed on A549 cell lines. The entrapment efficiency of M-LYC-OA-LNEs was 82.7 ± 1.6 %. The cellular uptake study showed that coated LNEs were preferably taken up by A549 cells than uncoated LNEs. The effective test by MTT assay showed better growth inhibition activity of M-LYC-OA-LNEs on A549 cell lines when compared with LYC-OA-LNEs and blank LNEs. These results demonstrated that M-LYC-OA-LNEs could be a promising formulation for tumor targeting delivery of LYC with the potential of being applied in the diagnosis and treatment of cancer. PMID:23227126

  11. Differentially transcriptional regulation on cell cycle pathway by silver nanoparticles from ionic silver in larval zebrafish (Danio rerio).

    PubMed

    Kang, Jae Soon; Bong, Jinjong; Choi, Jin-Soo; Henry, Theodore B; Park, June-Woo

    2016-10-28

    Silver nanoparticles (AgNPs) have a strong antibacterial activity and the relevant modes of actions have regarded as direct or indirect causes of toxicity observed in the environment. In this study, the transcriptomic profiles in larval zebrafish (Danio rerio) exposed to AgNPs (about 50 nm in size) and AgNO3 as a comparative ionic silver were investigated and analyzed using differential expressed gene (DEG), Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses. Results indicated that underlying molecular mechanisms are different each other. Interestingly, the global gene expression profiling showed that cell cycle pathway is affected by both AgNPs and dissolved Ag(+), however its regulation pattern was opposite each other. To the best of our knowledge, the up-regulation of cell cycle pathway by AgNPs and down-regulation by Ag(+) is the first reporting and suggests the distinguished toxicological perspective from a well-known hypothesis that Ag(+) mainly regulates the cell cycle. This study provides novel insights onto the genotoxicological mechanisms of AgNPs. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Action of angiotensin II, 5-hydroxytryptamine and adenosine triphosphate on ionic currents in single ear artery cells of the rabbit.

    PubMed

    Hughes, A D; Bolton, T B

    1995-10-01

    1. Angiotensin II, 5-hydroxytryptamine (5-HT) and adenosine triphosphate (ATP) evoked a transient inward current in isolated single car artery cells of rabbit held at -60 mV by whole cell voltage clamp in physiological saline using a KCL-containing pipette solution. Under these conditions agonist did not activate a calcium-dependent potassium current. 2. Responses to each agonist were transient and desensitized rapidly. Inward current at -60 mV holding potential was not abolished by blockade of voltage-dependent calcium channels or by buffering intracellular calcium with BAPTA, a calcium chelator, or following depletion of intracellular calcium stores with ryanodine. 3. The shape of the current-voltage relationships and the reversal potentials of the current induced by angiotensin II, 5-HT and ATP were similar under a variety of ionic conditions. Agonist-induced current was unaffected by replacing intracellular chloride with citrate ions or by replacing intracellular sodium with caesium or extracellular sodium with barium or calcium. Replacement of extracellular sodium with Tris shifted the reversal potential in all cases by around 30 mV negatively. 4. These data suggest that angiotensin II, 5-HT and ATP activate similar cationic conductances which are relatively non-selective allowing mono- and divalent cations to cross the smooth muscle cell membrane. These channels may allow the influx of calcium under physiological conditions.

  13. Heme-bound iron activates placenta growth factor in erythroid cells via erythroid Krüppel-like factor.

    PubMed

    Wang, Xunde; Mendelsohn, Laurel; Rogers, Heather; Leitman, Susan; Raghavachari, Nalini; Yang, Yanqin; Yau, Yu Ying; Tallack, Michael; Perkins, Andrew; Taylor, James G; Noguchi, Constance Tom; Kato, Gregory J

    2014-08-07

    In adults with sickle cell disease (SCD), markers of iron burden are associated with excessive production of the angiogenic protein placenta growth factor (PlGF) and high estimated pulmonary artery pressure. Enforced PlGF expression in mice stimulates production of the potent vasoconstrictor endothelin-1, producing pulmonary hypertension. We now demonstrate heme-bound iron (hemin) induces PlGF mRNA >200-fold in a dose- and time-dependent fashion. In murine and human erythroid cells, expression of erythroid Krüppel-like factor (EKLF) precedes PlGF, and its enforced expression in human erythroid progenitor cells induces PlGF mRNA. Hemin-induced expression of PlGF is abolished in EKLF-deficient murine erythroid cells but rescued by conditional expression of EKLF. Chromatin immunoprecipitation reveals that EKLF binds to the PlGF promoter region. SCD patients show higher level expression of both EKLF and PlGF mRNA in circulating blood cells, and markers of iron overload are associated with high PlGF and early mortality. Finally, PlGF association with iron burden generalizes to other human diseases of iron overload. Our results demonstrate a specific mechanistic pathway induced by excess iron that is linked in humans with SCD and in mice to markers of vasculopathy and pulmonary hypertension. These trials were registered at www.clinicaltrials.gov as #NCT00007150, #NCT00023296, #NCT00081523, and #NCT00352430.

  14. Making maxillary barbels with a proximal-distal gradient of Wnt signals in matrix-bound mesenchymal cells

    PubMed Central

    Figueroa, Francisco; Singer, Susan S.; LeClair, Elizabeth E.

    2015-01-01

    The evolution of specific appendages is made possible by the ontogenetic deployment of general cell signaling pathways. Many fishes, amphibians and reptiles have unique skin appendages known as barbels, which are poorly understood at the cellular and molecular level. In this study, we examine the cell arrangements, cell division patterns, and gene expression profiles associated with the zebrafish maxillary barbel, or ZMB. The earliest cellular organization of the ZMB is an internal whorl of mesenchymal cells in the dermis of the maxilla; there is no epithelial placode, nor any axially-elongated epithelial cells as expected of an apical ectodermal ridge (AER). As the ZMB develops, cells in S-phase are at first distributed randomly throughout the appendage, gradually transitioning to a proliferative population concentrated at the distal end. By observing ZMB ontogenetic stages in a Wnt-responsive transgenic reporter line, TCFsiam, we identified a strongly fluorescent mesenchymal cell layer within these developing appendages. Using an in vitro explant culture technique on developing barbel tissues, we co-localized the fluorescent label in these cells with the mitotic marker EdU. Surprisingly, TCF+ cells showed little proliferation, indicating a slow-cycling subpopulation. Transmission electron microscopy of the ZMB located the TCF+ cells in a single, circumferential layer within the barbel’s matrix core. Morphologically, these cells resemble fibroblasts or osteoblasts; in addition to their matrix-bound location, they are identified by their pancake-shaped nuclei, abundant rough endoplasmic reticulum, and cytoplasmic extensions into the surrounding extracellular matrix. Taken together, these features define a novel mesenchymal cell population in zebrafish, the ‘TCF+ core cells.’ A working model of barbel development is proposed, in which these minimally mitotic mesodermal cells produce collagenous matrix in response to ectodermally-derived Wnt signals deployed in

  15. Cell death detection and ionic homeostasis monitoring with digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Pavillon, Nicolas; Kühn, Jonas; Jourdain, Pascal; Depeursinge, Christian; Magistretti, Pierre J.; Marquet, Pierre

    2011-07-01

    Digital holographic microscopy is an interferometric technique enabling the measurement of the quantitative phase shifts induced by cell bodies. We correlate the phase signal measured on neurons with calcium imaging measured by fluorescence on cells loaded with Fluo-4, to monitor responses to glutamate challenges, which provoke well-known calcium increases through activation of various membrane receptors. A very good correspondence can be identified between the two signals, showing the links between the phase signal, being a measure of the intracellular dilution, and the calcium concentration within cells. We then check cell viability by employing propidium iodide (PI), a fluorescent indicator relying on the cell membrane integrity loss to assess cell death. Strong intracellular calcium concentration is indeed known to induce excitotoxic effects, potentially inducing cell death. This enables showing that some cells cannot sustain the calcium saturation identified in our measurements, leading to subsequent cell death.

  16. Membrane-bound IL-22 after de novo production in tuberculosis and anti-M.tuberculosis effector function of IL-22+CD4+ T cells

    PubMed Central

    Zeng, Gucheng; Chen, Crystal Y.; Huang, Dan; Yao, Shuyu; Wang, Richard C.; Chen, Zheng W.

    2013-01-01

    The role of IL-22-producing CD4+ T cells in intracellular pathogen infections is poorly characterized. IL-22-producing CD4+ T cells may also express other effector molecules, and therefore synergize or contribute to anti-microbial effector function. This hypothesis cannot be tested by conventional approaches manipulating a single IL-22 cytokine at genetic and protein levels, and IL-22+ T cells cannot be purified for evaluation due to secretion nature of cytokines. Here, we surprisingly found that upon activation, CD4+ T cells in M. tuberculosis-infected macaques or humans could evolve into T effector cells bearing membrane-bound IL-22 after de novo IL-22 production. Membrane-bound IL-22+ CD4+ T effector cells appeared to mature in vivo and sustain membrane distribution in highly-inflammatory environments during active M. tuberculosis infection. NSOM/QD-based nanoscale molecular imaging revealed that membrane-bound IL-22, like CD3, distributed in membrane and engaged as ~100–200 nm nanoclusters or ~300–600 nm nanodomains for potential interaction with IL-22 receptor. Importantly, purified membrane-bound IL-22+ CD4+ T cells inhibited intracellular M. tuberculosis replication in macrophages. Our findings suggest that IL-22-producing T cells can evolve to retain IL-22 on membrane for prolonged IL-22 half-lives and to exert efficient cell-cell interaction for anti-M. tuberculosis effector function. PMID:21632708

  17. Intravacuolar Membranes Regulate CD8 T Cell Recognition of Membrane-Bound Toxoplasma gondii Protective Antigen.

    PubMed

    Lopez, Jodie; Bittame, Amina; Massera, Céline; Vasseur, Virginie; Effantin, Grégory; Valat, Anne; Buaillon, Célia; Allart, Sophie; Fox, Barbara A; Rommereim, Leah M; Bzik, David J; Schoehn, Guy; Weissenhorn, Winfried; Dubremetz, Jean-François; Gagnon, Jean; Mercier, Corinne; Cesbron-Delauw, Marie-France; Blanchard, Nicolas

    2015-12-15

    Apicomplexa parasites such as Toxoplasma gondii target effectors to and across the boundary of their parasitophorous vacuole (PV), resulting in host cell subversion and potential presentation by MHC class I molecules for CD8 T cell recognition. The host-parasite interface comprises the PV limiting membrane and a highly curved, membranous intravacuolar network (IVN) of uncertain function. Here, using a cell-free minimal system, we dissect how membrane tubules are shaped by the parasite effectors GRA2 and GRA6. We show that membrane association regulates access of the GRA6 protective antigen to the MHC I pathway in infected cells. Although insertion of GRA6 in the PV membrane is key for immunogenicity, association of GRA6 with the IVN limits presentation and curtails GRA6-specific CD8 responses in mice. Thus, membrane deformations of the PV regulate access of antigens to the MHC class I pathway, and the IVN may play a role in immune modulation.

  18. Highly Selective Ionic Block Copolymer Membranes

    DTIC Science & Technology

    2010-11-10

    commonly used ionic polymer membrane in fuel cells ) as a function of methanol solution concentration using time-resolved FTIR-ATR spectroscopy. This...this field of study. These results suggest that methanol fuel cell performance and efficiency can be improved by developing new ionic polymers that...methanol sorption in the membrane and not diffusion. The typical assumption in ionic polymer development for the methanol fuel cell is that the diffusion

  19. A microfluidic device for measuring cell migration towards substrate-bound and soluble chemokine gradients

    PubMed Central

    Schwarz, Jan; Bierbaum, Veronika; Merrin, Jack; Frank, Tino; Hauschild, Robert; Bollenbach, Tobias; Tay, Savaş; Sixt, Michael; Mehling, Matthias

    2016-01-01

    Cellular locomotion is a central hallmark of eukaryotic life. It is governed by cell-extrinsic molecular factors, which can either emerge in the soluble phase or as immobilized, often adhesive ligands. To encode for direction, every cue must be present as a spatial or temporal gradient. Here, we developed a microfluidic chamber that allows measurement of cell migration in combined response to surface immobilized and soluble molecular gradients. As a proof of principle we study the response of dendritic cells to their major guidance cues, chemokines. The majority of data on chemokine gradient sensing is based on in vitro studies employing soluble gradients. Despite evidence suggesting that in vivo chemokines are often immobilized to sugar residues, limited information is available how cells respond to immobilized chemokines. We tracked migration of dendritic cells towards immobilized gradients of the chemokine CCL21 and varying superimposed soluble gradients of CCL19. Differential migratory patterns illustrate the potential of our setup to quantitatively study the competitive response to both types of gradients. Beyond chemokines our approach is broadly applicable to alternative systems of chemo- and haptotaxis such as cells migrating along gradients of adhesion receptor ligands vs. any soluble cue. PMID:27819270

  20. Human Renal Normal, Tumoral, and Cancer Stem Cells Express Membrane-Bound Interleukin-15 Isoforms Displaying Different Functions.

    PubMed

    Azzi, Sandy; Gallerne, Cindy; Romei, Cristina; Le Coz, Vincent; Gangemi, Rosaria; Khawam, Krystel; Devocelle, Aurore; Gu, Yanhong; Bruno, Stefania; Ferrini, Silvano; Chouaib, Salem; Eid, Pierre; Azzarone, Bruno; Giron-Michel, Julien

    2015-06-01

    Intrarenal interleukin-15 (IL-15) participates to renal pathophysiology, but the role of its different membrane-bound isoforms remains to be elucidated. In this study, we reassess the biology of membrane-bound IL-15 (mb-IL-15) isoforms by comparing primary cultures of human renal proximal tubular epithelial cells (RPTEC) to peritumoral (ptumTEC), tumoral (RCC), and cancer stem cells (CSC/CD105(+)). RPTEC express a 14 to 16 kDa mb-IL-15, whose existence has been assumed but never formally demonstrated and likely represents the isoform anchored at the cell membrane through the IL-15 receptor α (IL-15Rα) chain, because it is sensitive to acidic treatment and is not competent to deliver a reverse signal. By contrast, ptumTEC, RCC, and CSC express a novel N-hyperglycosylated, short-lived transmembrane mb-IL-15 (tmb-IL-15) isoform around 27 kDa, resistant to acidic shock, delivering a reverse signal in response to its soluble receptor (sIL-15Rα). This reverse signal triggers the down-regulation of the tumor suppressor gene E-cadherin in ptumTEC and RCC but not in CSC/CD105(+), where it promotes survival. Indeed, through the AKT pathway, tmb-IL-15 protects CSC/CD105(+) from non-programmed cell death induced by serum starvation. Finally, both mb-IL-15 and tmb-IL-15 are sensitive to metalloproteases, and the cleaved tmb-IL-15 (25 kDa) displays a powerful anti-apoptotic effect on human hematopoietic cells. Overall, our data indicate that both mb-IL-15 and tmb-IL-15 isoforms play a complex role in renal pathophysiology downregulating E-cadherin and favoring cell survival. Moreover, "apparently normal" ptumTEC cells, sharing different properties with RCC, could contribute to organize an enlarged peritumoral "preneoplastic" environment committed to favor tumor progression. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  1. Factor VIII Is Synthesized in Human Endothelial Cells, Packaged in Weibel-Palade Bodies and Secreted Bound to ULVWF Strings.

    PubMed

    Turner, Nancy A; Moake, Joel L

    2015-01-01

    The cellular synthesis site and ensuing storage location for human factor VIII (FVIII), the coagulation protein deficient in hemophilia A, has been elusive. FVIII stability and half-life is dependent on non-covalent complex formation with von Willebrand factor (VWF) to avoid proteolysis and clearance. VWF is synthesized in megakaryocytes and endothelial cells, and is stored and secreted from platelet alpha granules and Weibel-Palade bodies of endothelial cells. In this paper we provide direct evidence for FVIII synthesis in 2 types of primary human endothelial cells: glomerular microvascular endothelial cells (GMVECs) and umbilical vein endothelial cells (HUVECs). Gene expression quantified by real time PCR revealed that levels of F8 and VWF are similar in GMVECs and HUVECs. Previous clinical studies have shown that stimulation of vasopressin V2 receptors causes parallel secretion of both proteins. In this study, we found that both endothelial cell types express AVPR2 (vasopressin V2 receptor gene) and that AVPR2 mRNA levels are 5-fold higher in GMVECs than HUVECs. FVIII and VWF proteins were detected by fluorescent microscopy in Weibel-Palade bodies within GMVECs and HUVECs using antibodies proven to be target specific. Visual presence of FVIII and VWF in Weibel-Palade bodies was confirmed by correlation measurements. The high extent of correlation was compared with negative correlation values obtained from FVIII detection with cytoplasmic proteins, β-actin and Factor H. FVIII activity was positive in GMVEC and HUVEC cell lysates. Stimulated GMVECs and HUVECs were found to secrete cell-anchored ultra-large VWF strings covered with bound FVIII.

  2. The Significance of Circulating and Cell-Bound Antibodies in Experimental Allergic Encephalomyelitis

    PubMed Central

    Gonatas, Nicholas K.; Gonatas, Jacqueline O.; Stieber, Anna; Lisak, Robert; Suzuki, Kunuhiko; Martenson, Russell E.

    1974-01-01

    Conjugates of horseradish peroxidase with myelin basic protein (BP) of guinea pig or Lewis rat were used to identify antibody-containing cells in draining lymph nodes during experimental allergic encephalomyelitis (EAE). Peroxidase activity was revealed for light and electron microscopic preparations with the diaminobenzidine reaction of Graham and Karnovsky. Basic proteins (BP) were also iodinated with 125I for determination of circulating antibody against BP by radio-immunoassay of 125I BP using coprecipitation with antirat IgG or with antirat serum proteins. Encephalitogenicity was lost after conjugation of guinea pig BP or Lewis rat BP with peroxidase, whereas iodination did not affect the encephalitogenicity of guinea pig or Lewis rat BPs. EAE was induced in Lewis rats with guinea pig or Lewis rat spinal cord BPs in complete Freund's adjuvant. Draining lymph nodes were studied by light and electron microscopy during the course of the immune reaction, and cells with specific antibody against BP were identified with the use of BP-horseradish peroxidase conjugates. Lymph node sections from animals immunized with high antigen doses (500 μg) showed numerous plasma cells with intracellular antibody against BP in medullary cords 10 days after immunization and 4 days prior to histologic appearance of EAE. Numbers of positive cells correlated with levels of circulating antibody against BP. Immunization with a low antigen dose (5 μg) resulted in EAE, few or no antibody-containing cells, and significantly lower levels of circulating antibody. Brown Norwegian rats, a strain resistant to EAE, immunized with 500 μg of BP had positive cells in draining lymph nodes and high levels of circulating antibody against BP in the absence of histologic evidence of EAE. Lewis rats injected with Lewis rat small BP failed to develop EAE. Nevertheless, these animals showed levels of circulating antibody and antibody-containing cells similar to those of animals which developed EAE after

  3. Electrochemical and structural characterization of polymer gel electrolytes based on a PEO copolymer and an imidazolium-based ionic liquid for dye-sensitized solar cells.

    PubMed

    Freitas, Flavio S; de Freitas, Jilian N; Ito, Bruno I; De Paoli, Marco-A; Nogueira, Ana F

    2009-12-01

    Polymer electrolytes based on mixtures of poly(ethylene oxide-co-propylene oxide) and 1-methyl-3-propyl-imidazolium iodide (MPII) were investigated, aiming at their application in dye-sensitized solar cells (DSSC). The interactions between the copolymer and the ionic liquid were analyzed by infrared spectroscopy and (1)H NMR. The results show interactions between the ether oxygen in the polymer and the hydrogen in the imidazolium cations. The ionic conductivities, electrochemical behaviors, and thermal properties of the electrolytes containing different concentrations of MPII were investigated. The electrolyte containing 70 wt % MPII presented the highest ionic conductivity (2.4 x 10(-3) S cm(-1)) and a diffusion coefficient of 1.9 x 10(-7) cm(2) s(-1). The influence of LiI addition to the electrolytes containing different concentrations of MPII was also investigated. The DSSC assembled with the electrolyte containing 70 wt % MPII showed an efficiency of 3.84% at 100 mW cm(-2). The stability of the devices for a period of 30 days was also evaluated using sealed cells. The devices assembled with the electrolyte containing less ionic liquid showed to be more stable.

  4. Aspergillus oryzae lectin induces anaphylactoid oedema and mast cell activation through its interaction with fucose of mast cell-bound non-specific IgE.

    PubMed

    Yamaki, K; Yoshino, S

    2011-11-01

    We investigated whether Aspergillus oryzae lectin (AOL), a fucose-specific lectin, induces anaphylactoid reactions and mast cell activation. The injection of AOL into footpads of mice produced a dose-related acute paw oedema. The AOL-induced oedema was attenuated by predose of histamine H1 receptor blocker or pretreatment of the lectin with fucose before injection and was not observed in SCID and mast cell-deficient WBB6F1-W/Wv mice. These results suggested that the AOL-induced anaphylactoid reaction was mediated by histamine released from mast cells. In addition, the activation of mast cells was seemed to be induced by the crosslinking of IgE on the cell surface following the binding of AOL to fucose residues in IgE. Consistent with the in vivo results, AOL induced the degranulation of the rat mast cell line RBL2H3 sensitized with monoclonal IgE. As AOL induced the increase in intracellular Ca(2+) concentration of IgE-sensitized RBL2H3 cells as well as antigen stimulation, AOL could input signals from FcεRI. The degranulation of IgE-sensitized RBL2H3 cells by AOL was diminished by pretreatment of AOL with fucose. Defucosylated IgE did not induce degranulation of RBL2H3 cells in response to AOL stimulation, in spite of its ability to induce degranulation by antigen stimulation as intact IgE. These results indicated that AOL bound to fucose residue of IgE causing antigen-independent IgE-mediated mast cell activation and anaphylactoid reactions in vitro and in vivo, respectively. AOL bound to human IgE as well as to mouse IgE, suggesting the possible implication of AOL in the allergic response to Aspergillus oryzae in humans.

  5. Outward Bound.

    ERIC Educational Resources Information Center

    Outward Bound, Inc., Andover, MA.

    The Outward Bound concept was developed in Germany and Great Britain with the saving of human life as the ultimate goal. Courses are designed to help students discover their true physical and mental limits through development of skills including emergency medical aid, firefighting, search and rescue, mountaineering, and sailing. Five Outward Bound…

  6. Contents of soluble, cell-wall-bound and exuded phlorotannins in the brown alga Fucus vesiculosus, with implications on their ecological functions.

    PubMed

    Koivikko, Riitta; Loponen, Jyrki; Honkanen, Tuija; Jormalainen, Veijo

    2005-01-01

    Phlorotannins are ubiquitous secondary metabolites in brown algae that are phenotypically plastic and suggested to have multiple ecological roles. Traditionally, phlorotannins have been quantified as total soluble phlorotannins. Here, we modify a quantification procedure to measure, for the first time, the amount of cell-wall-bound phlorotannins. We also optimize the quantification of soluble phlorotannins. We use these methods to study the responses of soluble and cell-wall-bound phlorotannin to nutrient enrichment in growing and nongrowing parts of the brown alga Fucus vesiculosus. We also examine the effects of nutrient shortage and herbivory on the rate of phlorotannin exudation. Concentrations of cell-wall-bound phlorotannins were much lower than concentrations of soluble phlorotannins; we also found that nutrient treatment over a period of 41 days affected only soluble phlorotannins. Concentrations of each phlorotannin type correlated positively between growing and nongrowing parts of individual seaweeds. However, within nongrowing thalli, soluble and cell-wall-bound phlorotannins were negatively correlated, whereas within growing thalli there was no correlation. Phlorotannins were exuded from the thallus in all treatments. Herbivory increased exudation, while a lack of nutrients had no effect on exudation. Because the amount of cell-wall-bound phlorotannins is much smaller than the amount of soluble phlorotannins, the major function of phlorotannins appears to be a secondary one.

  7. Free and Cell Wall-Bound Polyamines under Long-Term Water Stress Applied at Different Growth Stages of ×Triticosecale Wittm

    PubMed Central

    Hura, Tomasz; Dziurka, Michał; Hura, Katarzyna; Ostrowska, Agnieszka; Dziurka, Kinga

    2015-01-01

    Background Long-stemmed and semi-dwarf cultivars of triticale were exposed to water stress at tillering, heading and anthesis stage. Quantitative determination of free and cell wall-bound polyamines, i.e. agmatine, cadaverine, putrescine, spermidine and spermine, was supplemented with an analysis of quantitative relationships between free and cell wall-bound polyamines. Results The content of free and cell wall-bound polyamines varied depending on the development stage, both under optimal and water stress conditions. Drought-induced increase in free agmatine content was observed at all developmental stages in long-stemmed cultivar. A depletion of spermidine and putrescine was also reported in this cultivar, and spermidine was less abundant in semi-dwarf cultivar exposed to drought stress at the three analyzed developmental stages. Changes in the content of the other free polyamines did not follow a steady pattern reflecting the developmental stages. On the contrary, the content of cell wall-bound polyamines gradually increased from tillering, through heading and until anthesis period. Conclusion Water stress seemed to induce a progressive decrease in the content of free polyamines and an accumulation of cell wall-bound polyamines. PMID:26247474

  8. How cumulative error in grid cell firing is literally bounded by the environment.

    PubMed

    Hayman, Robin; Burgess, Neil

    2015-05-06

    In this issue of Neuron, Hardcastle et al. (2015) show that the spatial firing patterns of grid cells accumulate error, drifting coherently, until reset by encounters with environmental boundaries. These results reveal important aspects of the neural dynamics of self-localization from self-motion and environmental information.

  9. Hydrodynamic forces on a wall-bound leukocyte due to interactions with flowing red cells

    NASA Astrophysics Data System (ADS)

    Isfahani, Amir H. G.; Freund, Jonathan B.

    2011-11-01

    As part of both healthy and pathologically physiological mechanisms sphere-like white blood cells (leukocytes) adhere to the walls of small blood vessels. We use quantitative numerical simulations to compare the forces from flowing red blood cells on a wall-adhered leukocyte to a homogenized model of blood at the same flow conditions. We model the highly flexible red blood cells using a fast O (N log N) boundary integral formulation. These elastic membranes deform substantially but strongly resist surface dilatation. They enclose a higher than plasma viscosity hemoglobin solution. The no-slip condition is enforced on the stationary leukocyte as well as the vessel walls. Vessel diameters of 10 to 20 microns are studied. Different hematocrits, leukocyte shapes, and flow conditions are examined. In vessels comparable to the size of the cells, we show that the particulate character of blood significantly affects the magnitude of the forces that the leukocyte experiences, transiently increasing it well above the homogenized-blood prediction: for example, for a tube hematocrit of 25 % and a spherical protrusion with a diameter 0.75 that of the tube, the average forces are increased by about 40 % and the local forces by more than 100 % relative to those expected for a blood model homogenized by its effective viscosity.

  10. The lantibiotic NAI-107 binds to bactoprenol-bound cell wall precursors and impairs membrane functions.

    PubMed

    Münch, Daniela; Müller, Anna; Schneider, Tanja; Kohl, Bastian; Wenzel, Michaela; Bandow, Julia Elisabeth; Maffioli, Sonia; Sosio, Margherita; Donadio, Stefano; Wimmer, Reinhard; Sahl, Hans-Georg

    2014-04-25

    The lantibiotic NAI-107 is active against Gram-positive bacteria including vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus. To identify the molecular basis of its potency, we studied the mode of action in a series of whole cell and in vitro assays and analyzed structural features by nuclear magnetic resonance (NMR). The lantibiotic efficiently interfered with late stages of cell wall biosynthesis and induced accumulation of the soluble peptidoglycan precursor UDP-N-acetylmuramic acid-pentapeptide (UDP-MurNAc-pentapeptide) in the cytoplasm. Using membrane preparations and a complete cascade of purified, recombinant late stage peptidoglycan biosynthetic enzymes (MraY, MurG, FemX, PBP2) and their respective purified substrates, we showed that NAI-107 forms complexes with bactoprenol-pyrophosphate-coupled precursors of the bacterial cell wall. Titration experiments indicate that first a 1:1 stoichiometric complex occurs, which then transforms into a 2:1 (peptide: lipid II) complex, when excess peptide is added. Furthermore, lipid II and related molecules obviously could not serve as anchor molecules for the formation of defined and stable nisin-like pores, however, slow membrane depolarization was observed after NAI-107 treatment, which could contribute to killing of the bacterial cell.

  11. Reply to "Comment on 'Modeling of electrode polarization for electrolytic cells with a limited ionic adsorption' ".

    PubMed

    Sawada, Atsushi

    2014-05-01

    The dielectric properties of dilute electrolytic solution cells have been measured in a low-frequency region, and the dielectric spectra have been analyzed in terms of space-charge polarization by using the Nernst-Planck (NP) model in the presence of ionic adsorption on electrodes [Phys. Rev. E 88, 032406 (2013)]. In the NP model, the internal electric field of the cell is considered to be approximately equal to the external field. In a Comment by Alexe-Ionescu et al. [Phys. Rev. E 89, 056401 (2014).] on our paper [Phys. Rev. E 88, 032406 (2013)], they claim the invalidity of the NP model and the necessity of the conventional Poisson-Nernst-Planck (PNP) model for the data analysis. Their criticisms are, however, originated from a viewpoint for determining the internal electric field, that is different from our approach. In this Reply, we show the validity of the NP model referring to our previous paper in which the conventional PNP model has been modified so as to correctly describe the actual internal field.

  12. Investigation of Ion Channel Activities of Gramicidin A in the Presence of Ionic Liquids Using Model Cell Membranes.

    PubMed

    Ryu, Hyunil; Lee, Hwankyu; Iwata, Seigo; Choi, Sangbaek; Kim, Moon Ki; Kim, Young-Rok; Maruta, Shinsaku; Kim, Sun Min; Jeon, Tae-Joon

    2015-07-20

    Ionic liquids (ILs) are considered to be green solvents because of their non-volatility. Although ILs are relatively safe in the atmospheric environment, they may be toxic in other environments. Our previous research showed that the cytotoxicity of ILs to biological organisms is attributable to interference with cell membranes by IL insertion. However, the effects of ILs on ion channels, which play important roles in cell homeostasis, have not been comprehensively studied to date. In this work, we studied the interactions between ILs and lipid bilayer membranes with gramicidin A ion channels. We used two methods, namely electrical and fluorescence measurements of ions that permeate the membrane. The lifetimes of channels were increased by all the ILs tested in this work via stabilizing the compressed structure of the lipid bilayer and the rate of ion flux through gA channels was decreased by changing the membrane surface charge. The former effect, which increased the rate of ion flux, was dominant at high salt concentrations, whereas the latter, which decreased the rate of ion flux, was dominant at low salt concentrations. The effects of ILs increased with increasing concentration and alkyl chain length. The experimental results were further studied using molecular dynamics simulations.

  13. Investigation of Ion Channel Activities of Gramicidin A in the Presence of Ionic Liquids Using Model Cell Membranes

    PubMed Central

    Ryu, Hyunil; Lee, Hwankyu; Iwata, Seigo; Choi, Sangbaek; Ki Kim, Moon; Kim, Young-Rok; Maruta, Shinsaku; Min Kim, Sun; Jeon, Tae-Joon

    2015-01-01

    Ionic liquids (ILs) are considered to be green solvents because of their non-volatility. Although ILs are relatively safe in the atmospheric environment, they may be toxic in other environments. Our previous research showed that the cytotoxicity of ILs to biological organisms is attributable to interference with cell membranes by IL insertion. However, the effects of ILs on ion channels, which play important roles in cell homeostasis, have not been comprehensively studied to date. In this work, we studied the interactions between ILs and lipid bilayer membranes with gramicidin A ion channels. We used two methods, namely electrical and fluorescence measurements of ions that permeate the membrane. The lifetimes of channels were increased by all the ILs tested in this work via stabilizing the compressed structure of the lipid bilayer and the rate of ion flux through gA channels was decreased by changing the membrane surface charge. The former effect, which increased the rate of ion flux, was dominant at high salt concentrations, whereas the latter, which decreased the rate of ion flux, was dominant at low salt concentrations. The effects of ILs increased with increasing concentration and alkyl chain length. The experimental results were further studied using molecular dynamics simulations. PMID:26189604

  14. Retroviral gene transfer into primary human NK cells activated by IL-2 and K562 feeder cells expressing membrane-bound IL-21.

    PubMed

    Streltsova, Maria A; Barsov, Eugene; Erokhina, Sofia A; Kovalenko, Elena I

    2017-11-01

    Natural killer (NK) cells are capable of rapidly recognizing and efficiently killing tumor cells. This makes them a potentially promising agent for cancer immunotherapy. Additional genetic modifications of NK cells may further improve their anti-tumor efficacy. Numerous technical challenges associated with gene delivery into NK cells have significantly tempered this approach. We achieved efficient retroviral vector transduction of primary human NK cells that were stimulated by a combination of IL-2 and engineered K562 cells expressing membrane-bound IL-21. The activated NK cells were in less differentiated state and expressed NK cell activation receptors NKG2D, NKp30, CD16, and were highly HLA-DR-positive. This NK cell population was highly susceptible to the transduction by both GFP- and NGFR-expressing retroviral vectors, with transduction efficiency exceeding 50%. More mature CD57(+) NK cell population was generally resistant to retroviral vector transduction because of poor response to the stimulation. Our findings may facilitate retroviral vector-mediated genetic engineering of human primary NK cells for future immunotherapies. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Cell-bound IgE and increased expression of Fc epsilon-receptors on dendritic cells in cutaneous infiltrates of mycosis fungoides.

    PubMed Central

    Preesman, A H; Van de Winkel, J G; Magnusson, C G; Toonstra, J; van der Putte, S C; van Vloten, W A

    1991-01-01

    Skin biopsies of 31 non-atopic patients, 20 with mycosis fungoides, six with psoriasis and five with contact dermatitis, and of five non-atopic healthy controls were compared for the presence of cell-bound IgE and vacant IgE binding sites. IgE+ cells were demonstrated in the cutaneous infiltrate of nine (45%) patients with mycosis fungoides, two (33%) with psoriasis and one (20%) with contact dermatitis. Following pre-incubation of skin sections with IgE myeloma protein to saturate vacant IgE-binding sites, 14 out of 16 patients (88%) with stage I mycosis fungoides, five (83%) patients with psoriasis and one (20%) with contact dermatitis showed an increase in the number of IgE+ cells. While cell-bound IgE was positively related to serum IgE levels the expression of IgE-binding sites was not. All IgE+ cells were HLA-DR+ dendritic cells identified as either macrophages (CD68+, CD14+) or Langerhans cells (CD1+). Skin biopsies of non-atopic healthy controls or clinically uninvolved skin in mycosis fungoides had neither any IgE+ cells nor any vacant binding sites. Inhibition studies with IgG1, IgG4 and IgE myeloma proteins as well as with several enzymatic fragments of IgE demonstrated that IgE interacted with Fc epsilon-receptors through isotype-specific structures on the Fc epsilon-fragment. Four anti-CD23 monoclonal antibodies, however, were unable to stain vacant Fc epsilon-receptors nor could they block IgE-binding. We hypothesize that locally-secreted lymphokines, like IL-4 or interferon-gamma, induce Fc epsilon-receptors on dendritic cells in the cutaneous infiltrate and that these receptors become occupied in parallel with elevated serum IgE levels. Images Fig. 1 Fig. 2 PMID:1834378

  16. Analysis of Major Histocompatibility Complex-Bound HIV Peptides Identified from Various Cell Types Reveals Common Nested Peptides and Novel T Cell Responses.

    PubMed

    Rucevic, Marijana; Kourjian, Georgio; Boucau, Julie; Blatnik, Renata; Garcia Bertran, Wilfredo; Berberich, Matthew J; Walker, Bruce D; Riemer, Angelika B; Le Gall, Sylvie

    2016-10-01

    Despite the critical role of epitope presentation for immune recognition, we still lack a comprehensive definition of HIV peptides presented by HIV-infected cells. Here we identified 107 major histocompatibility complex (MHC)-bound HIV peptides directly from the surface of live HIV-transfected 293T cells, HIV-infected B cells, and primary CD4 T cells expressing a variety of HLAs. The majority of peptides were 8 to 12 amino acids (aa) long and mostly derived from Gag and Pol. The analysis of the total MHC-peptidome and of HLA-A02-bound peptides identified new noncanonical HIV peptides of up to 16 aa that could not be predicted by HLA anchor scanning and revealed an heterogeneous surface peptidome. Nested sets of surface HIV peptides included optimal and extended HIV epitopes and peptides partly overlapping or distinct from known epitopes, revealing new immune responses in HIV-infected persons. Surprisingly, in all three cell types, a majority of Gag peptides derived from p15 rather than from the most immunogenic p24. The cytosolic degradation of peptide precursors in corresponding cells confirmed the generation of identified surface-nested peptides. Cytosolic degradation revealed peptides commonly produced in all cell types and displayed by various HLAs, peptides commonly produced in all cell types and selectively displayed by specific HLAs, and peptides produced in only one cell type. Importantly, we identified areas of proteins leading to common presentations of noncanonical peptides by several cell types with distinct HLAs. These peptides may benefit the design of immunogens, focusing T cell responses on relevant markers of HIV infection in the context of HLA diversity. The recognition of HIV-infected cells by immune T cells relies on the presentation of HIV-derived peptides by diverse HLA molecules at the surface of cells. The landscape of HIV peptides displayed by HIV-infected cells is not well defined. Considering the diversity of HLA molecules in the human

  17. Analysis of Major Histocompatibility Complex-Bound HIV Peptides Identified from Various Cell Types Reveals Common Nested Peptides and Novel T Cell Responses

    PubMed Central

    Rucevic, Marijana; Kourjian, Georgio; Boucau, Julie; Blatnik, Renata; Garcia Bertran, Wilfredo; Berberich, Matthew J.; Walker, Bruce D.; Riemer, Angelika B.

    2016-01-01

    ABSTRACT Despite the critical role of epitope presentation for immune recognition, we still lack a comprehensive definition of HIV peptides presented by HIV-infected cells. Here we identified 107 major histocompatibility complex (MHC)-bound HIV peptides directly from the surface of live HIV-transfected 293T cells, HIV-infected B cells, and primary CD4 T cells expressing a variety of HLAs. The majority of peptides were 8 to 12 amino acids (aa) long and mostly derived from Gag and Pol. The analysis of the total MHC-peptidome and of HLA-A02-bound peptides identified new noncanonical HIV peptides of up to 16 aa that could not be predicted by HLA anchor scanning and revealed an heterogeneous surface peptidome. Nested sets of surface HIV peptides included optimal and extended HIV epitopes and peptides partly overlapping or distinct from known epitopes, revealing new immune responses in HIV-infected persons. Surprisingly, in all three cell types, a majority of Gag peptides derived from p15 rather than from the most immunogenic p24. The cytosolic degradation of peptide precursors in corresponding cells confirmed the generation of identified surface-nested peptides. Cytosolic degradation revealed peptides commonly produced in all cell types and displayed by various HLAs, peptides commonly produced in all cell types and selectively displayed by specific HLAs, and peptides produced in only one cell type. Importantly, we identified areas of proteins leading to common presentations of noncanonical peptides by several cell types with distinct HLAs. These peptides may benefit the design of immunogens, focusing T cell responses on relevant markers of HIV infection in the context of HLA diversity. IMPORTANCE The recognition of HIV-infected cells by immune T cells relies on the presentation of HIV-derived peptides by diverse HLA molecules at the surface of cells. The landscape of HIV peptides displayed by HIV-infected cells is not well defined. Considering the diversity of HLA

  18. Characterization of the B Cell Transcriptome Bound by RNA-Binding Proteins with iCLIP.

    PubMed

    Díaz-Muñoz, Manuel D; Monzón-Casanova, Elisa; Turner, Martin

    2017-01-01

    Posttranscriptional regulation of gene expression shapes the B cell transcriptome and controls messenger RNA (mRNA) translation into protein. Recent reports have highlighted the importance of RNA binding proteins (RBPs) for mRNA splicing, subcellular location, stability, and translation during B lymphocyte development, activation, and differentiation. Here we describe individual-nucleotide resolution UV cross-linking and immunoprecipitation (iCLIP) in primary lymphocytes, a method that maps RNA-protein interactions in a genome-wide scale allowing mechanistic analysis of RBP function. We discuss the latest improvements in iCLIP technology and provide some examples of how integration of the RNA-protein interactome with other high-throughput mRNA sequencing methodologies uncovers the important role of RBP-mediated RNA regulation in key biological cell processes.

  19. Senescent cells expose and secrete an oxidized form of membrane-bound vimentin as revealed by a natural polyreactive antibody

    PubMed Central

    Frescas, David; Roux, Christelle M.; Aygun-Sunar, Semra; Gleiberman, Anatoli S.; Krasnov, Peter; Kurnasov, Oleg V.; Strom, Evguenia; Virtuoso, Lauren P.; Wrobel, Michelle; Osterman, Andrei L.; Antoch, Marina P.; Mett, Vadim; Chernova, Olga B.; Gudkov, Andrei V.

    2017-01-01

    Studying the phenomenon of cellular senescence has been hindered by the lack of senescence-specific markers. As such, detection of proteins informally associated with senescence accompanies the use of senescence-associated β-galactosidase as a collection of semiselective markers to monitor the presence of senescent cells. To identify novel biomarkers of senescence, we immunized BALB/c mice with senescent mouse lung fibroblasts and screened for antibodies that recognized senescence-associated cell-surface antigens by FACS analysis and a newly developed cell-based ELISA. The majority of antibodies that we isolated, cloned, and sequenced belonged to the IgM isotype of the innate immune system. In-depth characterization of one of these monoclonal, polyreactive natural antibodies, the IgM clone 9H4, revealed its ability to recognize the intermediate filament vimentin. By using 9H4, we observed that senescent primary human fibroblasts express vimentin on their cell surface, and MS analysis revealed a posttranslational modification on cysteine 328 (C328) by the oxidative adduct malondialdehyde (MDA). Moreover, elevated levels of secreted MDA-modified vimentin were detected in the plasma of aged senescence-accelerated mouse prone 8 mice, which are known to have deregulated reactive oxygen species metabolism and accelerated aging. Based on these findings, we hypothesize that humoral innate immunity may recognize senescent cells by the presence of membrane-bound MDA-vimentin, presumably as part of a senescence eradication mechanism that may become impaired with age and result in senescent cell accumulation. PMID:28193858

  20. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study

    PubMed Central

    Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

    2016-01-01

    Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca2+ after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca2+, and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca2+ was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca2+ homeostasis in mesophyll cells. PMID:26957564

  1. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study.

    PubMed

    Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

    2016-06-01

    Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca(2+) after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca(2+), and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca(2+) was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca(2+) homeostasis in mesophyll cells. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  2. Interaction of type A lantibiotics with undecaprenol-bound cell envelope precursors.

    PubMed

    Müller, Anna; Ulm, Hannah; Reder-Christ, Katrin; Sahl, Hans-Georg; Schneider, Tanja

    2012-06-01

    Lantibiotics are a unique group within the antimicrobial peptides characterized by the presence of thioether amino acids (lanthionine and methyllanthionine). These peptides are produced by and primarily act on Gram-positive bacteria exerting multiple activities at the cytoplasmic membrane of susceptible strains. Previously, the cell wall precursor lipid II was identified as the molecular target for the prototype lantibiotic nisin. Binding and sequestration of lipid II blocks the incorporation of the central cell wall precursor into the growing peptidoglycan network, thereby inhibiting the formation of a functional cell wall. Additionally, nisin combines this activity with a unique target-mediated pore formation, using lipid II as a docking molecule. The interaction with the pyrophosphate moiety of lipid II is crucial for nisin binding. We show that, besides binding to lipid II, nisin interacts with the lipid intermediates lipid III (undecaprenol-pyrophosphate-N-acetyl-glucosamine) and lipid IV (undecaprenol-pyrophosphate-N-acetyl-glucosamine-N-acetyl-mannosamine) of the wall teichoic acid (WTA) biosynthesis pathway. Binding of nisin to the precursors was observed at a stoichiometry of 2:1. The specific interaction with WTA precursors further promoted target-mediated pore formation in artificial lipid bilayers. Specific interactions with lipid III and lipid IV could also be demonstrated for related type A lantibiotics, for example, gallidermin, containing the conserved lipid-II-binding motif.

  3. Expression and Function of Cell Wall-Bound Cationic Peroxidase in Asparagus Somatic Embryogenesis

    PubMed Central

    Takeda, Hiroyuki; Kotake, Toshihisa; Nakagawa, Naoki; Sakurai, Naoki; Nevins, Donald J.

    2003-01-01

    Cultured asparagus (Asparagus officinalis L. cv Y6) cells induced to regenerate into whole plants through somatic embryogenesis secreted a 38-kD protein into cell walls. The full-length cDNA sequence of this protein (Asparagus officinalis peroxidase 1 [AoPOX1]) determined by reverse transcriptase-polymerase chain reaction showed similarity with plant peroxidases. AoPOX1 transcripts were particularly abundant during early somatic embryogenesis. To evaluate the in vivo function of AoPOX1 protein, purified recombinant AoPOX1 protein was reacted with a series of phenolic substrates. The AoPOX1 protein was effective in the metabolism of feruloyl (o-methoxyphenol)-substituted substrates, including coniferyl alcohol. The reaction product of coniferyl alcohol was fractionated and subjected to gas chromatography-mass spectrometry analysis and 1H-nuclear magnetic resonance analysis, indicating that the oxidation product of coniferyl alcohol in the presence of AoPOX1 was dehydrodiconiferyl alcohol. The concentration of dehydrodiconiferyl alcohol in the cultured medium of the somatic embryos was in the range of 10−8 m. Functions of the AoPOX1 protein in the cell differentiation are discussed. PMID:12692335

  4. Expression and function of cell wall-bound cationic peroxidase in asparagus somatic embryogenesis.

    PubMed

    Takeda, Hiroyuki; Kotake, Toshihisa; Nakagawa, Naoki; Sakurai, Naoki; Nevins, Donald J

    2003-04-01

    Cultured asparagus (Asparagus officinalis L. cv Y6) cells induced to regenerate into whole plants through somatic embryogenesis secreted a 38-kD protein into cell walls. The full-length cDNA sequence of this protein (Asparagus officinalis peroxidase 1 [AoPOX1]) determined by reverse transcriptase-polymerase chain reaction showed similarity with plant peroxidases. AoPOX1 transcripts were particularly abundant during early somatic embryogenesis. To evaluate the in vivo function of AoPOX1 protein, purified recombinant AoPOX1 protein was reacted with a series of phenolic substrates. The AoPOX1 protein was effective in the metabolism of feruloyl (o-methoxyphenol)-substituted substrates, including coniferyl alcohol. The reaction product of coniferyl alcohol was fractionated and subjected to gas chromatography-mass spectrometry analysis and (1)H-nuclear magnetic resonance analysis, indicating that the oxidation product of coniferyl alcohol in the presence of AoPOX1 was dehydrodiconiferyl alcohol. The concentration of dehydrodiconiferyl alcohol in the cultured medium of the somatic embryos was in the range of 10(-8) M. Functions of the AoPOX1 protein in the cell differentiation are discussed.

  5. Fuel Cells Using the Protic Ionic Liquid and Rotator Phase Solid Electrolyte Principles

    DTIC Science & Technology

    2008-02-13

    Talk “High temperature Polymer Electrolyte Membrane Fuel Cells (HT- PEMFCs ) for Portable Power in Large-Scale Energy Storage Devices”, Paper Number 195...Membrane Fuel Cells (HT- PEMFCs ) for Portable Power in Large-Scale Energy Storage Devices”, Paper Number 195, 212th Meeting of the Electrochemical

  6. Method for producing electricity from a fuel cell having solid-oxide ionic electrolyte

    DOEpatents

    Mason, David M.

    1984-01-01

    Stabilized quadrivalent cation oxide electrolytes are employed in fuel cells at elevated temperatures with a carbon and/or hydrogen containing fuel anode and an oxygen cathode. The fuel cell is operated at elevated temperatures with conductive metallic coatings as electrodes and desirably having the electrolyte surface blackened. Of particular interest as the quadrivalent oxide is zirconia.

  7. Mesenchymal stromal cells induce epithelial-to-mesenchymal transition in human colorectal cancer cells through the expression of surface-bound TGF-β

    PubMed Central

    Mele, Valentina; Muraro, Manuele G; Calabrese, Diego; Pfaff, Dennis; Amatruda, Nunzia; Amicarella, Francesca; Kvinlaug, Brynn; Bocelli-Tyndall, Chiara; Martin, Ivan; Resink, Therese J; Heberer, Michael; Oertli, Daniel; Terracciano, Luigi; Spagnoli, Giulio C; Iezzi, Giandomenica

    2014-01-01

    Mesenchymal stem/stromal cells (MSC) are multipotent precursors endowed with the ability to home to primary and metastatic tumor sites, where they can integrate into the tumor-associated stroma. However, molecular mechanisms and outcome of their interaction with cancer cells have not been fully clarified. In this study, we investigated the effects mediated by bone marrow-derived MSC on human colorectal cancer (CRC) cells in vitro and in vivo. We found that MSC triggered epithelial-to-mesenchymal transition (EMT) in tumor cells in vitro, as indicated by upregulation of EMT-related genes, downregulation of E-cadherin and acquisition of mesenchymal morphology. These effects required cell-to-cell contact and were mediated by surface-bound TGF-β newly expressed on MSC upon coculture with tumor cells. In vivo tumor masses formed by MSC-conditioned CRC cells were larger and characterized by higher vessel density, decreased E-cadherin expression and increased expression of mesenchymal markers. Furthermore, MSC-conditioned tumor cells displayed increased invasiveness in vitro and enhanced capacity to invade peripheral tissues in vivo. Thus, by promoting EMT-related phenomena, MSC appear to favor the acquisition of an aggressive phenotype by CRC cells. PMID:24214914

  8. Mesenchymal stromal cells induce epithelial-to-mesenchymal transition in human colorectal cancer cells through the expression of surface-bound TGF-β.

    PubMed

    Mele, Valentina; Muraro, Manuele G; Calabrese, Diego; Pfaff, Dennis; Amatruda, Nunzia; Amicarella, Francesca; Kvinlaug, Brynn; Bocelli-Tyndall, Chiara; Martin, Ivan; Resink, Therese J; Heberer, Michael; Oertli, Daniel; Terracciano, Luigi; Spagnoli, Giulio C; Iezzi, Giandomenica

    2014-06-01

    Mesenchymal stem/stromal cells (MSC) are multipotent precursors endowed with the ability to home to primary and metastatic tumor sites, where they can integrate into the tumor-associated stroma. However, molecular mechanisms and outcome of their interaction with cancer cells have not been fully clarified. In this study, we investigated the effects mediated by bone marrow-derived MSC on human colorectal cancer (CRC) cells in vitro and in vivo. We found that MSC triggered epithelial-to-mesenchymal transition (EMT) in tumor cells in vitro, as indicated by upregulation of EMT-related genes, downregulation of E-cadherin and acquisition of mesenchymal morphology. These effects required cell-to-cell contact and were mediated by surface-bound TGF-β newly expressed on MSC upon coculture with tumor cells. In vivo tumor masses formed by MSC-conditioned CRC cells were larger and characterized by higher vessel density, decreased E-cadherin expression and increased expression of mesenchymal markers. Furthermore, MSC-conditioned tumor cells displayed increased invasiveness in vitro and enhanced capacity to invade peripheral tissues in vivo. Thus, by promoting EMT-related phenomena, MSC appear to favor the acquisition of an aggressive phenotype by CRC cells.

  9. Ionic crystals

    SciTech Connect

    Mahan, G.D.

    1985-03-01

    The theme of the second Petra School of Physics was the optical properties of solids. The author's lectures will discuss the theory of ionic crystals such as the alkali halides. The general topics will include a discussion of: the local electric fields, multipole polarizability, core level spectra, and electron energy levels. The subject of alkali halides is today regarded as unfashionable. They were quite popular years ago, but fashions and fancies in science have moved elsewhere. One should not think they are well understood. The author's impression of this field is that activity stopped, not because the problems were solved, but rather because the workers got tired of not being able to solve them. For example, we still do not have a good theory of crystal structure, since microscopic forces are not well characterized. One concludes that other quantities which depend upon forces, such as the elastic constants, are also not well understood, although theories of them are published all of the time. As another example, we still do not have a good theory of bonding. Here there are two camps: one which regards the bonding as ionic, while the other advocates significant amounts of covalency. Recently we have shown that both the elastic constants, and the amount of covalent bonding, depend significantly upon the higher multipole polarizabilities. In summary, the subject of ionic crystals is a field where there are still many unresolved issues awaiting good research. 21 refs., 5 figs., 4 tabs.

  10. A cell wall-bound adenosine nucleosidase is involved in the salvage of extracellular ATP in Solanum tuberosum.

    PubMed

    Riewe, David; Grosman, Lukasz; Fernie, Alisdair R; Zauber, Henrik; Wucke, Cornelia; Geigenberger, Peter

    2008-10-01

    Extracellular ATP (eATP) has recently been demonstrated to play a crucial role in plant development and growth. To investigate the fate of eATP within the apoplast, we used intact potato (Solanum tuberosum) tuber slices as an experimental system enabling access to the apoplast without interference of cytosolic contamination. (i) Incubation of intact tuber slices with ATP led to the formation of ADP, AMP, adenosine, adenine and ribose, indicating operation of apyrase, 5'-nucleotidase and nucleosidase. (ii) Measurement of apyrase, 5'-nucleotidase and nucleosidase activities in fractionated tuber tissue confirmed the apoplastic localization for apyrase and phosphatase in potato and led to the identification of a novel cell wall-bound adenosine nucleosidase activity. (iii) When intact tuber slices were incubated with saturating concentrations of adenosine, the conversion of adenosine into adenine was much higher than adenosine import into the cell, suggesting a potential bypass of adenosine import. Consistent with this, import of radiolabeled adenine into tuber slices was inhibited when ATP, ADP or AMP were added to the slices. (iv) In wild-type plants, apyrase and adenosine nucleosidase activities were found to be co-regulated, indicating functional linkage of these enzymes in a shared pathway. (v) Moreover, adenosine nucleosidase activity was reduced in transgenic lines with strongly reduced apoplastic apyrase activity. When taken together, these results suggest that a complete ATP salvage pathway is present in the apoplast of plant cells.

  11. Progesterone-induced activation of membrane-bound progesterone receptors in murine macrophage cells.

    PubMed

    Lu, Jing; Reese, Joshua; Zhou, Ying; Hirsch, Emmet

    2015-02-01

    Parturition is an inflammatory process mediated to a significant extent by macrophages. Progesterone (P4) maintains uterine quiescence in pregnancy, and a proposed functional withdrawal of P4 classically regulated by nuclear progesterone receptors (nPRs) leads to labor. P4 can affect the functions of macrophages despite the reported lack of expression of nPRs in these immune cells. Therefore, in this study we investigated the effects of the activation of the putative membrane-associated PR on the function of macrophages (a key cell for parturition) and discuss the implications of these findings for pregnancy and parturition. In murine macrophage cells (RAW 264.7), activation of mPRs by P4 modified to be active only extracellularly by conjugation to BSA (P4BSA, 1.0×10(-7) mol/l) caused a pro-inflammatory shift in the mRNA expression profile, with significant upregulation of the expression of cyclooxygenase 2 (COX2 (Ptgs2)), Il1B, and Tnf and downregulation of membrane progesterone receptor alpha (Paqr7) and oxytocin receptor (Oxtr). Pretreatment with PD98059, a MEK1/2 inhibitor, significantly reduced P4BSA-induced expression of mRNA of Il1B, Tnf, and Ptgs2. Inhibition of protein kinase A (PKA) by H89 blocked P4BSA-induced expression of Il1B and Tnf mRNA. P4BSA induced rapid phosphorylation of MEK1/2 and CREB (a downstream target of PKA). This phosphorylation was inhibited by pretreatment with PD98059 and H89, respectively, revealing that MEK1/2 and PKA are two of the components involved in mPR signaling. Taken together, these results indicate that changes in membrane progesterone receptor alpha expression and signaling in macrophages are associated with the inflammatory responses; and that these changes might contribute to the functional withdrawal of P4 related to labor.

  12. Cytoplasmic long noncoding RNAs are frequently bound to and degraded at ribosomes in human cells

    PubMed Central

    Carlevaro-Fita, Joana; Rahim, Anisa; Guigó, Roderic; Vardy, Leah A.; Johnson, Rory

    2016-01-01

    Recent footprinting studies have made the surprising observation that long noncoding RNAs (lncRNAs) physically interact with ribosomes. However, these findings remain controversial, and the overall proportion of cytoplasmic lncRNAs involved is unknown. Here we make a global, absolute estimate of the cytoplasmic and ribosome-associated population of stringently filtered lncRNAs in a human cell line using polysome profiling coupled to spike-in normalized microarray analysis. Fifty-four percent of expressed lncRNAs are detected in the cytoplasm. The majority of these (70%) have >50% of their cytoplasmic copies associated with polysomal fractions. These interactions are lost upon disruption of ribosomes by puromycin. Polysomal lncRNAs are distinguished by a number of 5′ mRNA-like features, including capping and 5′UTR length. On the other hand, nonpolysomal “free cytoplasmic” lncRNAs have more conserved promoters and a wider range of expression across cell types. Exons of polysomal lncRNAs are depleted of endogenous retroviral insertions, suggesting a role for repetitive elements in lncRNA localization. Finally, we show that blocking of ribosomal elongation results in stabilization of many associated lncRNAs. Together these findings suggest that the ribosome is the default destination for the majority of cytoplasmic long noncoding RNAs and may play a role in their degradation. PMID:27090285

  13. Cytoplasmic long noncoding RNAs are frequently bound to and degraded at ribosomes in human cells.

    PubMed

    Carlevaro-Fita, Joana; Rahim, Anisa; Guigó, Roderic; Vardy, Leah A; Johnson, Rory

    2016-06-01

    Recent footprinting studies have made the surprising observation that long noncoding RNAs (lncRNAs) physically interact with ribosomes. However, these findings remain controversial, and the overall proportion of cytoplasmic lncRNAs involved is unknown. Here we make a global, absolute estimate of the cytoplasmic and ribosome-associated population of stringently filtered lncRNAs in a human cell line using polysome profiling coupled to spike-in normalized microarray analysis. Fifty-four percent of expressed lncRNAs are detected in the cytoplasm. The majority of these (70%) have >50% of their cytoplasmic copies associated with polysomal fractions. These interactions are lost upon disruption of ribosomes by puromycin. Polysomal lncRNAs are distinguished by a number of 5' mRNA-like features, including capping and 5'UTR length. On the other hand, nonpolysomal "free cytoplasmic" lncRNAs have more conserved promoters and a wider range of expression across cell types. Exons of polysomal lncRNAs are depleted of endogenous retroviral insertions, suggesting a role for repetitive elements in lncRNA localization. Finally, we show that blocking of ribosomal elongation results in stabilization of many associated lncRNAs. Together these findings suggest that the ribosome is the default destination for the majority of cytoplasmic long noncoding RNAs and may play a role in their degradation. © 2016 Carlevaro-Fita et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  14. Hydrolysis of penicillins and related compounds by the cell-bound penicillin acylase of Escherichia coli

    PubMed Central

    Cole, M.

    1969-01-01

    1. A method is given for the preparation of penicillin acylase by using Escherichia coli N.C.I.B. 8743 and a strain selected for higher yield. The enzyme is associated with the bacterial cells and removes the side chains of penicillins to give 6-amino-penicillanic acid and a carboxylic acid. 2. The rates of penicillin deacylation indicated that p-hydroxybenzylpenicillin was the best substrate, followed in diminishing order by benzyl-, dl-α-hydroxybenzyl-, 2-furylmethyl-, 2-thienylmethyl-, d-α-aminobenzyl-, n-propoxymethyl- and isobutoxymethyl-penicillin. Phenylpenicillin and dl-α-carboxybenzylpenicillin were not substrates and phenoxymethyl-penicillin was very poor. 3. Amides and esters of the above penicillins were also substrates for the deacylation reaction, as were cephalosporins with a thienylmethyl side chain. 4. For the deacylation of 2-furylmethylpenicillin at 21° the optimum pH was 8·2. The optimum temperature was 60° at pH7. 5. By using selection A of N.C.I.B. 8743 and determining reaction velocities by assaying yields of 6-amino-penicillanic acid in a 10min. reaction at 50° and pH8·2, the Km for benzylpenicillin was found to be about 30mm and the Km for 2-furylmethylpenicillin, about 10mm. The Vmax. values were 0·6 and 0·24μmole/min./mg. of bacterial cells respectively. PMID:4982417

  15. Lateral migration and equilibrium shape and position of a single red blood cell in bounded Poiseuille flows.

    PubMed

    Shi, Lingling; Pan, Tsorng-Whay; Glowinski, Roland

    2012-11-01

    Lateral migration and equilibrium shape and position of a single red blood cell (RBC) in bounded two-dimensional Poiseuille flows are investigated by using an immersed boundary method. An elastic spring model is applied to simulate the skeleton structure of a RBC membrane. We focus on studying the properties of lateral migration of a single RBC in Poiseuille flows by varying the initial position, the initial angle, the swelling ratio (s), the membrane bending stiffness of RBC (k{b}), the maximum velocity of fluid flow (u{max}), and the degree of confinement. The combined effect of the deformability, the degree of confinement, and the shear gradient of the Poiseuille flow make the RBCs migrate toward a certain cross-sectional equilibrium position, which lies either on the center line of the channel or off center line. For s>0.8, the speed of the migration at the beginning decreases as one increases the swelling ratio s. But for s<0.8, the speed of the migration at the beginning is an increasing function of the swelling ratio s. Two motions of oscillation and vacillating breathing (swing) of RBCs are observed. The distance Y{d} between the cell mass center of the equilibrium position and the center line of the channel increases with increasing the Reynolds number Re and reaches a peak, then decreases with increasing Re. The peak of Re is a decreasing function of the swelling ratio (s<1.0). The cell membrane energy of the equilibrium position is an increasing function as Re increases. The slipper-shaped cell is more stable than the parachute-shaped one in the sense that the energy stored in the former is lower than that in the latter. For a given Re, the bigger the swelling ratio (s<1.0), the lower the cell membrane energy.

  16. Peroxidases Bound to the Growing Lignin Polymer Produce Natural Like Extracellular Lignin in a Cell Culture of Norway Spruce

    PubMed Central

    Warinowski, Tino; Koutaniemi, Sanna; Kärkönen, Anna; Sundberg, Ilari; Toikka, Merja; Simola, Liisa Kaarina; Kilpeläinen, Ilkka; Teeri, Teemu H.

    2016-01-01

    Lignin, an important component of plant cell walls, is a polymer of monolignols derived from the phenylpropanoid pathway. Monolignols are oxidized in the cell wall by oxidative enzymes (peroxidases and/or laccases) to radicals, which then couple with the growing lignin polymer. We have investigated the characteristics of the polymerization reaction by producing lignin polymers in vitro using different oxidative enzymes and analyzing the structures formed with NMR. The ability of the enzymes to oxidize high-molecular-weight compounds was tested using cytochrome c as a substrate. The results support an idea that lignin structure is largely determined by the concentration ratios of the monolignol (coniferyl alcohol) and polymer radicals involved in the coupling reaction. High rate of the lignin polymer oxidation compared to monolignol oxidation leads to a natural-like structure. The high relative rate can be achieved by an open active site of the oxidative enzyme, close proximity of the enzyme with the polymeric substrate or simply by high enzymatic activity that consumes monolignols rapidly. Monolignols, which are oxidized efficiently, can be seen as competitive inhibitors of polymer oxidation. Our results indicate that, at least in a Norway spruce (Picea abies L. Karst.) cell culture, a group of apoplastic, polymer-oxidizing peroxidases bind to the lignin polymer and are responsible for production of natural-like lignin in cell suspension cultures in vivo, and also in vitro. The peroxidases bound to the extracellular lignin had the highest ability to bind to various cell wall polymers in vitro. Extracellular lignin contains pectin-type sugars, making them possible attachment points for these cationic peroxidases. PMID:27803704

  17. Lateral migration and equilibrium shape and position of a single red blood cell in bounded Poiseuille flows

    NASA Astrophysics Data System (ADS)

    Shi, Lingling; Pan, Tsorng-Whay; Glowinski, Roland

    2012-11-01

    Lateral migration and equilibrium shape and position of a single red blood cell (RBC) in bounded two-dimensional Poiseuille flows are investigated by using an immersed boundary method. An elastic spring model is applied to simulate the skeleton structure of a RBC membrane. We focus on studying the properties of lateral migration of a single RBC in Poiseuille flows by varying the initial position, the initial angle, the swelling ratio (s*), the membrane bending stiffness of RBC (kb), the maximum velocity of fluid flow (umax), and the degree of confinement. The combined effect of the deformability, the degree of confinement, and the shear gradient of the Poiseuille flow make the RBCs migrate toward a certain cross-sectional equilibrium position, which lies either on the center line of the channel or off center line. For s*>0.8, the speed of the migration at the beginning decreases as one increases the swelling ratio s*. But for s*<0.8, the speed of the migration at the beginning is an increasing function of the swelling ratio s*. Two motions of oscillation and vacillating breathing (swing) of RBCs are observed. The distance Yd between the cell mass center of the equilibrium position and the center line of the channel increases with increasing the Reynolds number Re and reaches a peak, then decreases with increasing Re. The peak of Re is a decreasing function of the swelling ratio (s*<1.0). The cell membrane energy of the equilibrium position is an increasing function as Re increases. The slipper-shaped cell is more stable than the parachute-shaped one in the sense that the energy stored in the former is lower than that in the latter. For a given Re, the bigger the swelling ratio (s*<1.0), the lower the cell membrane energy.

  18. In vitro inhibitory effects of disodium cromoglycate on ionic transports involved in sickle cell dehydration.

    PubMed

    Bizumukama, Léonidas; Ferster, Alina; Gulbis, Béatrice; Kumps, Alain; Cotton, Frédéric

    2009-01-01

    The antiallergic and antiasthmatic drug disodium cromoglycate (DSCG) has also demonstrated an activity against sickle cell disease, but the mechanism of this action still remains unknown. Na(+) and K(+) fluxes were studied in red cells obtained from 9 patients affected with sickle cell disease in the absence or in the presence of 1 mM of DSCG and deoxygenated under an N(2) flow during up to 24 h. A significant inhibiting effect of DSCG on the intracellular K(+) exit and the Na(+) entry was observed. These results demonstrate that DSCG partially inhibits the abnormal K(+) loss which is implicated in the dehydration of the sickle cell and the stimulation of sickling. Copyright 2009 S. Karger AG, Basel.

  19. Host cell factor-1 recruitment to E2F-bound and cell-cycle-control genes is mediated by THAP11 and ZNF143.

    PubMed

    Parker, J Brandon; Yin, Hanwei; Vinckevicius, Aurimas; Chakravarti, Debabrata

    2014-11-06

    Host cell factor-1 (HCF-1) is a metazoan transcriptional coregulator essential for cell-cycle progression and cell proliferation. Current models suggest a mechanism whereby HCF-1 functions as a direct coregulator of E2F proteins, facilitating the expression of genes necessary for cell proliferation. In this report, we show that HCF-1 recruitment to numerous E2F-bound promoters is mediated by the concerted action of zinc finger transcription factors THAP11 and ZNF143, rather than E2F proteins directly. THAP11, ZNF143, and HCF-1 form a mutually dependent complex on chromatin, which is independent of E2F occupancy. Disruption of the THAP11/ZNF143/HCF-1 complex results in altered expression of cell-cycle control genes and leads to reduced cell proliferation, cell-cycle progression, and cell viability. These data establish a model in which a THAP11/ZNF143/HCF-1 complex is a critical component of the transcriptional regulatory network governing cell proliferation.

  20. Ionic mechanisms subserving mechanosensory transduction and neural integration in statocyst hair cells of Hermissenda

    NASA Technical Reports Server (NTRS)

    Farley, Joseph

    1988-01-01

    The neural processing of gravitational-produced sensory stimulation of statocyst hair cells in the nudibranch mollusk Hermissenda was studied. The goal in these studies was to understand how: gravireceptor neurons sense or transduce gravitational forces, gravitational stimulation is integrated so as to produce a graded receptor potential, and ultimately the generation of an action potential, and various neural adaptation phenomena which hair cells exhibit arise. The approach to these problems was primarily electrophysical.

  1. The Ionic Permeability Changes during Acetylcholine-Induced Responses of Aplysia Ganglion Cells

    PubMed Central

    Sato, Makoto; Austin, George; Yai, Hideko; Maruhashi, Juro

    1968-01-01

    ACh-induced depolarization (D response) in D cells markedly decreases as the external Na+ is reduced. However, when Na+ is completely replaced with Mg++, the D response remains unchanged. When Na+ is replaced with Tris(hydroxymethyl)aminomethane, the D response completely disappears, except for a slight decrease in membrane resistance. ACh-induced hyperpolarization (H response) in H cells is markedly depressed as the external Cl- is reduced. Frequently, the reversal of the H response; i.e., depolarization, is observed during perfusion with Cl--free media. In cells which show both D and H responses superimposed, it was possible to separate these responses from each other by perfusing the cells with either Na+-free or Cl--free Ringer's solution. High [K+]0 often caused a marked hyperpolarization in either D or H cells. This is due to the primary effect of high [K+]0 on the presynaptic inhibitory fibers. The removal of this inhibitory afferent interference by applying Nembutal readily disclosed the predicted K+ depolarization. In perfusates containing normal [Na+]0, the effects of Ca++ and Mg++ on the activities of postsynaptic membrane were minimal, supporting the current theory that the effects of these ions on the synaptic transmission are mainly presynaptic. The possible mechanism of the hyperpolarization produced by simultaneous perfusion with both high [K+]0 and ACh in certain H cells is explained quantitatively under the assumption that ACh induces exclusively an increase in Cl- permeability of the H membrane. PMID:5648831

  2. Cytotoxicity towards CCO cells of imidazolium ionic liquids with functionalized side chains: preliminary QSTR modeling using regression and classification based approaches.

    PubMed

    Bubalo, Marina Cvjetko; Radošević, Kristina; Srček, Višnja Gaurina; Das, Rudra Narayan; Popelier, Paul; Roy, Kunal

    2015-02-01

    Within this work we evaluated the cytotoxicity towards the Channel Catfish Ovary (CCO) cell line of some imidazolium-based ionic liquids containing different functionalized and unsaturated side chains. The toxic effects were measured by the reduction of the WST-1 dye after 72 h exposure resulting in dose- and structure-dependent toxicities. The obtained data on cytotoxic effects of 14 different imidazolium ionic liquids in CCO cells, expressed as EC50 values, were used in a preliminary quantitative structure-toxicity relationship (QSTR) study employing regression- and classification-based approaches. The toxicity of ILs towards CCO was chiefly related to the shape and hydrophobicity parameters of cations. A significant influence of the quantum topological molecular similarity descriptor ellipticity (ε) of the imine bond was also observed.

  3. Ionic conduction in Sn 1- xSc xP 2O 7 for intermediate temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Hongtao; Zhang, Hongmin; Xiao, Guoxian; Zhang, Feng; Yu, Tian; Xiao, Jia; Ma, Guilin

    A novel series of mixed ion conductors, Sn 1- xSc xP 2O 7 (x = 0.03, 0.06, 0.09, 0.12), were synthesized by a solid-state reaction method. The conduction behaviors of the ion conductors in wet hydrogen atmosphere were investigated by some electrochemical methods including AC impedance spectroscopy, gas concentration cells in the temperature range of 323-523 K. It was found that the doping limit of Sc 3+ in SnP 2O 7 was between 9 mol% and 12 mol%. The highest conductivity was observed to be 2.76 × 10 -2 S cm -1 for the sample of x = 0.06 under wet H 2 atmosphere at 473 K. The ionic conduction was contributed mainly to proton and partially to oxide ion in wet hydrogen atmosphere from 373 K to 523 K. The H 2/air fuel cells using Sn 1- xSc xP 2O 7 (x = 0.03, 0.06, 0.09) as electrolytes (1.7 mm in thickness) generated the maximum power densities of 11.16 mW cm -2 for x = 0.03, 25.02 mW cm -2 for x = 0.06 and 14.34 mW cm -2 for x = 0.09 at 423 K, respectively. The results indicated that Sn 1- xSc xP 2O 7 is a promising solid electrolyte system for intermediate temperature fuel cells.

  4. Nonlinear QSAR modeling for predicting cytotoxicity of ionic liquids in leukemia rat cell line: an aid to green chemicals designing.

    PubMed

    Gupta, Shikha; Basant, Nikita; Singh, Kunwar P

    2015-08-01

    Safety assessment and designing of safer ionic liquids (ILs) are among the priorities of the chemists and toxicologists today. Computational approaches have been considered as appropriate methods for prior safety assessment of chemicals and tools to aid in structural designing. The present study is an attempt to investigate the chemical attributes of a wide variety of ILs towards their cytotoxicity in leukemia rat cell line IPC-81 through the development of nonlinear quantitative structure-activity relationship (QSAR) models in the light of the OECD principles for QSAR development. Here, the cascade correlation network (CCN), probabilistic neural network (PNN), and generalized regression neural networks (GRNN) QSAR models were established for the discrimination of ILs in four categories of cytotoxicity and their end-point prediction using few simple descriptors. The diversity and nonlinearity of the considered dataset were evaluated through computing the Euclidean distance and Brock-Dechert-Scheinkman statistics. The constructed QSAR models were validated with external test data. The predictive power of these models was established through a variety of stringent parameters recommended in QSAR literature. The classification QSARs rendered the accuracy of >86%, and the regression models yielded correlation (R(2)) of >0.90 in test data. The developed QSAR models exhibited high statistical confidence and identified the structural elements of the ILs responsible for their cytotoxicity and, hence, could be useful tools in structural designing of safer and green ILs.

  5. Ionic conductor with high conductivity as single-component electrolyte for efficient solid-state dye-sensitized solar cells.

    PubMed

    Wang, Hong; Li, Juan; Gong, Feng; Zhou, Gang; Wang, Zhong-Sheng

    2013-08-28

    Imidazolium iodide is an often used component in iodine-based dye-sensitized solar cells (DSSCs), but it cannot operate an efficient DSSC in the absence of iodine due to its low conductivity. For this study, lamellar solid iodide salts of imidazolium or piperidinium with an N-substituted propargyl group have been prepared and applied in solid-state DSSCs. Owing to the high conductivity arising from the lamellar structure, these solid-state ionic conductors can be used as single-component solid electrolytes to operate solid-state DSSCs efficiently without any additives in the electrolyte and post-treatments on the dye-loaded TiO2 films. With a propargyl group attached to the imidazolium ring, the conductivity is enhanced by about 4 × 10(4)-fold as compared to the alkyl-substituted imidazolium iodide. Solid-state DSSC with the 1-propargyl-3-methylimidazolium iodide as the single-component solid-state electrolyte has achieved a light-to-electricity power conversion efficiency of 6.3% under illumination of simulated AM1.5G solar light (100 mW cm(-2)), which also exhibits good long-term stability under continuous 1 sun soaking for 1500 h. This finding paves the way for development of high-conductivity single-component solid electrolytes for use in efficient solid-state DSSCs.

  6. Urokinase redistribution from the secreted to the cell-bound fraction in granulosa cells of rat preovulatory follicles.

    PubMed

    Macchione, E; Epifano, O; Stefanini, M; Belin, D; Canipari, R

    2000-04-01

    Plasminogen activators (PAs) have been shown to be synthesized in ovarian follicles of several mammalian species, where they contribute to the ovulation process. The type of PA secreted by granulosa cells is species-specific. In fact, whereas in the rat, gonadotropins stimulate tissue-type PA (tPA) production, the same hormonal stimulation induces urokinase PA (uPA) secretion in mouse cells. To investigate in more detail the hormonal regulation of this system, we used the rat ovary as a model in which we analyzed the production of PAs by theca-interstitial (TI) and granulosa cells obtained from preovulatory follicles after gonadotropin stimulation. In untreated rats, uPA was the predominant enzyme in both TI and granulosa cells. After hormonal stimulation, an increase in uPA and tPA activity was observed in both cell types. Surprisingly, only tPA mRNA increased in a time-dependent manner in both cell types, while uPA mRNA increased only in TI cells and actually decreased in granulosa cells. These divergent results between uPA enzyme activity and mRNA levels in granulosa cells were explained by studying the localization of the enzyme. Analysis of granulosa cell lysates showed that after hormonal stimulation, 60-70% of the uPA behaved as a cell-associated protein, suggesting that uPA, already present in the follicle, accumulates on the granulosa cell surface through binding to specific uPA receptors. The redistribution of uPA in granulosa cells and the differing regulation of the two PAs by gonadotropins in the rat ovary suggest that the two enzymes might have different functions during the ovulation process. Moreover, the ability of antibodies anti-tPA and anti-uPA to significantly inhibit ovulation only when coinjected with hCG confirmed that the PA contribution to ovulation occurs at the initial steps.

  7. Glutaraldehyde-Mediated Synthesis of Asparaginase-Bound Maghemite Nanocomposites: Cytotoxicity against Human Colon Adenocarcinoma Cells.

    PubMed

    Baskar, G; George, Garrick Bikku

    2016-01-01

    Drugs processed using nanobiotechnology may be more biocompatible, with sustainable and stabilised release or action. L-asparaginase produced from fungi has many advantages for treatment of lymphocytic leukemia with lesser side effect. In the present work, maghemite nanobiocomposites of fungal asparaginase were produced using glutaraldehyde-pretreated colloidal magnetic nanoparticles. Formation of nanobiocomposites was observed using laser light scattering and confirmed by UV-visible spectrophotometry with the absorption peak at 497 nm. The specific asparaginase activity was increased from 320 U/mg with crude asparaginase to 481.5 U/mg. FTIR analysis confirmed that primary amines are the functional groups involved in binding of asparaginase on magnetic nanoparticles. The average size of the produced nanobiocomposite was found in the range of 30 nm to 40 nm using histogram analysis. The magnetic nanobiocomposite of asparaginase synthesised using glutaraldehyde showed 90.75% cytotoxicity against human colon adenocarcinoma cell lines. Hence it can be used as an active anticancer drug with an augmented level of bioavailability.

  8. Long clinostation influence on the localization of free and weakly bound calcium in cell walls of Funaria hygrometrica moss protonema cells

    NASA Astrophysics Data System (ADS)

    Nedukha, E. M.

    The pyroantimonate method was used to study the localization of free and weakly bound calcium in cells of moss protonema of Funaria hygrometrica Hedw. cultivated on a clinostat (2 rev/min). Electroncytochemical study of control cells cultivated at 1 g revealed that granular precipitate marked chloroplasts, mitochondria, Golgi apparatus, lipid drops, nucleoplasma, nucleolus, nucleus membranes, cell walls and endoplasmic reticulum. In mitochondria the precipitate was revealed in stroma, in chloroplast it was found on thylakoids and envelope membranes. The cultivation of protonema on clinostat led to the intensification in cytochemical reaction product deposit. A considerable intensification of the reaction was noted in endomembranes, vacuoles, periplasmic space and cell walls. At the same time analysis of pectinase localization was made using the electroncytochemical method. A high reaction intensity in walls in comparison to that in control was found out to be a distinctive pecularity of the cells cultivated on clinostat. It testifies to the fact that increasing of freee calcium concentrations under conditions of clinostation is connected with pectinic substances hydrolysis and breaking of methoxy groups of pectins. Data obtained are discussed in relation to problems of possible mechanisms of disturbance in calcium balance of plant cells and the role of cell walls in gomeostasis of cell grown under conditions of simulated weighlessness.

  9. Regulation of Signaling at Regions of Cell-Cell Contact by Endoplasmic Reticulum-Bound Protein-Tyrosine Phosphatase 1B

    PubMed Central

    Haj, Fawaz G.; Sabet, Ola; Kinkhabwala, Ali; Wimmer-Kleikamp, Sabine; Roukos, Vassilis; Han, Hong-Mei; Grabenbauer, Markus; Bierbaum, Martin; Antony, Claude; Neel, Benjamin G.; Bastiaens, Philippe I.

    2012-01-01

    Protein-tyrosine phosphatase 1B (PTP1B) is a ubiquitously expressed PTP that is anchored to the endoplasmic reticulum (ER). PTP1B dephosphorylates activated receptor tyrosine kinases after endocytosis, as they transit past the ER. However, PTP1B also can access some plasma membrane (PM)-bound substrates at points of cell-cell contact. To explore how PTP1B interacts with such substrates, we utilized quantitative cellular imaging approaches and mathematical modeling of protein mobility. We find that the ER network comes in close proximity to the PM at apparently specialized regions of cell-cell contact, enabling PTP1B to engage substrate(s) at these sites. Studies using PTP1B mutants show that the ER anchor plays an important role in restricting its interactions with PM substrates mainly to regions of cell-cell contact. In addition, treatment with PTP1B inhibitor leads to increased tyrosine phosphorylation of EphA2, a PTP1B substrate, specifically at regions of cell-cell contact. Collectively, our results identify PM-proximal sub-regions of the ER as important sites of cellular signaling regulation by PTP1B. PMID:22655028

  10. SPARC is a possible predictive marker for albumin-bound paclitaxel in non-small-cell lung cancer

    PubMed Central

    Komiya, Kazutoshi; Nakamura, Tomomi; Nakashima, Chiho; Takahashi, Koichiro; Umeguchi, Hitomi; Watanabe, Naomi; Sato, Akemi; Takeda, Yuji; Kimura, Shinya; Sueoka-Aragane, Naoko

    2016-01-01

    Objectives Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) produced good tumor response in cases with lung squamous cell carcinoma, one of the most difficult cancers to treat. Secreted protein acidic and rich in cysteine (SPARC) binds to albumin, suggesting that SPARC plays an important role in tumor uptake of nab-paclitaxel. There is as yet no predictive marker for cytotoxic agents against non-small-cell lung cancer (NSCLC), and hence we believed that SPARC expression might be associated with tumor response to nab-paclitaxel. Patients and methods We studied stromal SPARC reactivity and its association with clinicopathological characteristics in 200 cases of NSCLC using a custom tissue microarray fabricated in our laboratory by immunohistochemical staining. We also investigated the relationship between stromal SPARC reactivity and tumor response to nab-paclitaxel using biopsy or surgical specimens obtained from advanced or recurrent lung cancer patients. Results High SPARC stromal reactivity (>50% of optical fields examined) was detected in 16.5% of cases and intermediate SPARC reactivity (10%–50%) in 56% of cases. High expression in cancer cells was rare (five cases). Stromal SPARC level was correlated with smoking index, squamous cell carcinoma, and vessel invasion. Furthermore, patients with high stromal SPARC reactivity in biopsy specimens such as transbronchial lung biopsy or surgical specimens tended to respond better to nab-paclitaxel. Conclusion Stromal SPARC was detected by immunohistochemical staining in ∼70% of NSCLC cases, and good tumor response to nab-paclitaxel was correlated with high stromal SPARC reactivity. SPARC may be a useful predictive marker for selecting patients likely to respond favorably to nab-paclitaxel treatment. PMID:27822069

  11. Lecithin-Bound Iodine Prevents Disruption of Tight Junctions of Retinal Pigment Epithelial Cells under Hypoxic Stress

    PubMed Central

    Sugimoto, Masahiko; Kondo, Mineo

    2016-01-01

    Aim. We investigated whether lecithin-bound iodine (LBI) can protect the integrity of tight junctions of retinal pigment epithelial cells from hypoxia. Method. Cultured human retinal pigment epithelial (ARPE-19) cells were pretreated with LBI. To mimic hypoxic conditions, cells were incubated with CoCl2. We compared the integrity of the tight junctions (TJs) of control to cells with either LBI alone, CoCl2 alone, or LBI + CoCl2. The levels of cytokines in the conditioned media were also determined. Results. Significant decrease in the zonula occludens-1 (ZO-1) intensity in the CoCl2 group compared to the control (5787.7 ± 4126.4 in CoCl2 group versus 29244.6 ± 2981.2 in control; average ± standard deviation). But the decrease was not significant in the LBI + CoCl2 (27189.0 ± 11231.1). The levels of monocyte chemoattractant protein-1 (MCP-1) and Chemokine (C-C Motif) Ligand 11 (CCL-11) were significantly higher in the CoCl2 than in the control (340.8 ± 43.3 versus 279.7 ± 68.3 pg/mL for MCP-1, and 15.2 ± 12.9 versus 12.5 ± 6.1 pg/mL for CCL-11. With LBI pretreatment, the levels of both cytokines were decreased to 182.6 ± 23.8 (MCP-1) and 5.46 ± 1.9 pg/mL for CCL-11). Blockade of MCP-1 or CCL-11 also shows similar result representing TJ protection from hypoxic stress. Conclusions. LBI results in a protective action from hypoxia. PMID:27340563

  12. Structural characterization and anticancer activity of cell-bound exopolysaccharide from Lactobacillus helveticus MB2-1.

    PubMed

    Li, Wei; Xia, Xiudong; Tang, Weizhi; Ji, Juan; Rui, Xin; Chen, Xiaohong; Jiang, Mei; Zhou, Jianzhong; Zhang, Qiuqin; Dong, Mingsheng

    2015-04-08

    A novel cell-bound exopolysaccharide (c-EPS) was isolated from Lactobacillus helveticus MB2-1 by ultrasonic extraction, anion exchange, and gel filtration chromatography before being structurally characterized. The c-EPS is a heteropolysaccharide with an average molecular weight of 1.83 × 10(5) Da and is composed of glucose, mannose, galactose, rhamnose, and arabinose at a molar ratio of 3.12:1.01:1.00:0.18:0.16. Methylation analysis and nuclear magnetic resonance analysis revealed that the c-EPS is a linear glucomannogalactan containing repeating units of → 6)-β-D-Manp-(1 → 3)-β-D-Glcp-(1 → 3)-β-D-Glcp-(1 → 3)-β-D-Glcp-(1 → 4)-α-D-Galp-(1 → and trace amounts of Rhap-(1 → and (1 → 4)-Arap residues. Complex formation with Congo red demonstrated a triple-strand helical conformation for the c-EPS. Scanning electron microscopy of the c-EPS revealed many regular feather-like structural units. Topographical examination of c-EPS by atomic force microscopy revealed that the c-EPS formed rounded-to-spherical lumps with different sizes and chain formations. Furthermore, preliminary in vitro tests revealed that c-EPS significantly inhibited the proliferation of HepG-2, BGC-823, and especially HT-29 cancer cells.

  13. Modelling of the batch biosorption system: study on exchange of protons with cell wall-bound mineral ions.

    PubMed

    Mishra, Vishal

    2015-01-01

    The interchange of the protons with the cell wall-bound calcium and magnesium ions at the interface of solution/bacterial cell surface in the biosorption system at various concentrations of protons has been studied in the present work. A mathematical model for establishing the correlation between concentration of protons and active sites was developed and optimized. The sporadic limited residence time reactor was used to titrate the calcium and magnesium ions at the individual data point. The accuracy of the proposed mathematical model was estimated using error functions such as nonlinear regression, adjusted nonlinear regression coefficient, the chi-square test, P-test and F-test. The values of the chi-square test (0.042-0.017), P-test (<0.001-0.04), sum of square errors (0.061-0.016), root mean square error (0.01-0.04) and F-test (2.22-19.92) reported in the present research indicated the suitability of the model over a wide range of proton concentrations. The zeta potential of the bacterium surface at various concentrations of protons was observed to validate the denaturation of active sites.

  14. Ability of polymer-bound P-glycoprotein inhibitor ritonavir to overcome multidrug resistance in various resistant neuroblastoma cell lines.

    PubMed

    Koziolová, Eva; Chytil, Petr; Etrych, Tomáš; Janoušková, Olga

    2017-09-08

    Polymer prodrugs can considerably improve the treatment of tumors with multidrug resistance, often caused by overexpression of P-glycoprotein (P-gp). Here, we present the effect of the N-(2-hydroxypropyl) methacrylamide-based polymer conjugate with P-gp inhibitor ritonavir (RIT) on the increase of free doxorubicin (DOX) and polymer-bound DOX cytotoxicity in the human neuroblastoma 4 cell line and its resistant clones to different cytostatics. The increase in cytotoxicity after polymer-RIT conjugate pretreatment was higher for the lines overexpressing P-gp and less pronounced for those with decreased P-gp levels. Moreover, the effect of polymer conjugate containing inhibitor and DOX on the same polymer chain was lower than that of two individual polymer conjugates used sequentially. In conclusion, the polymer-RIT conjugate can significantly increase the cytotoxicity of free DOX and polymer-DOX conjugates in cells with various multidrug resistance origins and can thus be considered a suitable therapeutic enhancer of polymer prodrugs.

  15. Optimization of extraction conditions and fatty acid characterization of Lactobacillus pentosus cell-bound biosurfactant/bioemulsifier.

    PubMed

    Vecino, Xanel; Barbosa-Pereira, Letricia; Devesa-Rey, Rosa; Cruz, José M; Moldes, Ana B

    2015-01-01

    There is currently much interest in the use of natural biosurfactants and bioemulsifiers, mainly in the cosmetic, pharmaceutical and food industries. However, there are no studies on the optimization of the extraction conditions of cell-bound biosurfactants. In this work, a biosurfactant with emulsifier properties was extracted from Lactobacillus pentosus cells, under different extraction conditions, and characterized. During extraction, the most influential independent variable, concerning the emulsifying capacity of biosurfactant, was the operation time, followed by temperature and salt concentration. Biosurfactant from L. pentosus was evaluated by Fourier transform infrared spectroscopy and the composition of fatty acids was analyzed by gas chromatography-mass spectrometry. The hydrophobic chain of the biosurfactant from L. pentosus comprises 548 g kg(-1) linoelaidic acid (C18:2), 221 g kg(-1) oleic or elaidic acid (C18:1), 136 g kg(-1) palmitic acid (C16) and 95 g kg(-1) stearic acid (C18). In addition, emulsions of water and rosemary oil were stabilized with a biosurfactant produced by L. pentosus and compared with emulsions stabilized with polysorbate 20. The optimum extraction conditions of biosurfactant were achieved at 45 °C at 120 min and using 9 g kg(-1) of salt. In all the assays biosurfactant from L. pentosus yielded more stable emulsions and higher emulsion volumes than polysorbate 20. © 2014 Society of Chemical Industry.

  16. Augmentation of hemagglutination by low ionic conditions.

    PubMed

    Rosenfield, R E; Shaikh, S H; Innella, F; Kaczera, Z; Kochwa, S

    1979-01-01

    Short incubation at 37 C, 80 per cent reduction in ionic concentration and removal of liquid phases after each reaction step, provided the basis for the construction of four new serologic tests for alloantibodies to human erythrocytes. In the first, the incubation fluid was replaced with protamine sulfate to aggregate intensely the evaluated red blood cells. After dispersal by phosphate buffer, residual antibody mediated agglutination could be discerned. As a second method, this low ionic polycation (LIP) test was followed by a normal ionic IgG antiglobulin test (LIP-AGT). A third method employed low ionic washing of erythrocytes and low ionic antiglobulin serum (LIAGT). Finally, a modified LIP test was conducted entirely under low ionic conditions and followed by a low ionic antiglobulin test (modified LIP-AGT). LIP, LIP-AGT and LIAGT were successfully employed for all routine blood bank serology tests. Their sensitivity and impact on blood bank performance are described.

  17. Light-Independent Ionic Transport in Inorganic Perovskite and Ultrastable Cs-Based Perovskite Solar Cells.

    PubMed

    Zhou, Wenke; Zhao, Yicheng; Zhou, Xu; Fu, Rui; Li, Qi; Zhao, Yao; Liu, Kaihui; Yu, Dapeng; Zhao, Qing

    2017-09-07

    Due to light-induced effects in CH3NH3-based perovskites, such as ion migration, defects formation, and halide segregation, the degradation of CH3NH3-based perovskite solar cells under maximum power point is generally implicated. Here we demonstrated that the effect of light-enhanced ion migration in CH3NH3PbI3 can be eliminated by inorganic Cs substitution, leading to an ultrastable perovskite solar cell. Quantitatively, the ion migration barrier for CH3NH3PbI3 is 0.62 eV under dark conditions, larger than that of CsPbI2Br (0.45 eV); however, it reduces to 0.07 eV for CH3NH3PbI3 under illumination, smaller than that for CsPbI2Br (0.43 eV). Meanwhile, photoinduced halide segregation is also suppressed in Cs-based perovskites. Cs-based perovskite solar cells retained >99% of the initial efficiency (10.3%) after 1500 h of maximum power point tracking under AM1.5G illumination, while CH3NH3PbI3 solar cells degraded severely after 50 h of operation. Our work reveals an uncovered mechanism for stability improvement by inorganic cation substitution in perovskite-based optoelectronic devices.

  18. Evidence of quinone metabolites of naphthalene covalently bound to sulfur nucleophiles of proteins of murine Clara cells after exposure to naphthalene.

    PubMed

    Zheng, J; Cho, M; Jones, A D; Hammock, B D

    1997-09-01

    Naphthalene-induced Clara cell toxicity in the mouse is associated with the covalent binding of electrophilic metabolites to cellular proteins. Epoxide and quinone metabolites of naphthalene are proposed to be the reactive metabolites responsible for covalent binding to proteins. To identify the nature of reactive metabolites bound to proteins (cysteine residues), we alkaline-permethylated proteins obtained from mouse Clara cells incubated with 0.5 mM naphthalene in vitro. Alkaline permethylation of protein adducts produced (methylthio)naphthalene derivatives detected by GC-MS. 3,4-Dimethoxy(methylthio)naphthalene was observed to be a predominant (methylthio)naphthalene derivative formed in the alkaline-permethylated protein sample obtained from Clara cells after exposure to naphthalene. This indicates that 1,2-naphthoquinone is a major metabolite covalently bound to cysteine residues of the cellular proteins. We have developed an immunoblotting approach to detect 1,2-naphthoquinone covalently bound to cysteine residues of proteins [Zheng, J., and Hammock, B. D. (1996) Chem. Res. Toxicol. 9, 904-909]. To identify 1,2-naphthoquinone covalently bound to sulfur nucleophiles of proteins, homogenates obtained from naphthalene-exposed Clara cells were separated by SDS-PAGE followed by Western blotting and immunostaining with the antibodies. Two protein bands with 24 and 25 kDa were detected by the antibodies, further supporting the view that 1,2-naphthoquinone is a reactive metabolite of naphthalene which binds to Clara cell proteins in vitro.

  19. Flow cytometric evaluation of the contribution of ionic silver to genotoxic potential of nanosilver in human liver HepG2 and colon Caco2 cells.

    PubMed

    Sahu, Saura C; Njoroge, Joyce; Bryce, Steven M; Zheng, Jiwen; Ihrie, John

    2016-04-01

    Exposure to nanosilver found in food- and cosmetics-related consumer products is of public concern because of the lack of information about its safety. In this study, two widely used in vitro cell culture models, human liver HepG2 and colon Caco2 cells, and the flow cytometric micronucleus (FCMN) assay were evaluated as tools for rapid predictive screening of the potential genotoxicity of nanosilver. Recently, we reported the genotoxicity of 20 nm nanosilver using these systems. In the current study presented here, we tested the hypothesis that the nanoparticle size and cell types were critical determinants of its genotoxicity. To test this hypothesis, we used the FCMN assay to evaluate the genotoxic potential of 50 nm nanosilver of the same shape, composition, surface charge and obtained from the same commercial source using the same experimental conditions and in vitro models (HepG2 and Caco2) as previously tested for the 20 nm silver. Results of our study show that up to the concentrations tested in these cultured cell test systems, the smaller (20 nm) nanoparticle is genotoxic to both the cell types by inducing micronucleus (MN). However, the larger (50 nm) nanosilver induces MN only in HepG2 cells, but not in Caco2 cells. Also in this study, we evaluated the contribution of ionic silver to the genotoxic potential of nanosilver using silver acetate as the representative ionic silver. The MN frequencies in HepG2 and Caco2 cells exposed to the ionic silver in the concentration range tested are not statistically significant from the control values except at the top concentrations for both the cell types. Therefore, our results indicate that the ionic silver may not contribute to the MN-forming ability of nanosilver in HepG2 and Caco2 cells. Also our results suggest that the HepG2 and Caco2 cell cultures and the FCMN assay are useful tools for rapid predictive screening of a genotoxic potential of food- and cosmetics-related chemicals including nanosilver.

  20. Temporal sequence of metabolic and ionic events in glucose-stimulated clonal pancreatic beta-cells (HIT).

    PubMed

    Civelek, V N; Deeney, J T; Kubik, K; Schultz, V; Tornheim, K; Corkey, B E

    1996-05-01

    Stimulation of insulin release by glucose requires increased metabolism of glucose and a rise in cytosolic free Ca2+ in the pancreatic beta-cell. It is accompanied by increases in respiratory rate, pyridine and flavin nucleotide reduction state, intracellular pH and the ATP/ADP ratio. To test alternative proposals of the regulatory relationships among free Ca2+, mitochondrial metabolism and cellular energy state, we determined the temporal sequence of these metabolic and ionic changes following addition of glucose to clonal pancreatic beta-cells (HIT). Combined measurements of the native fluorescence of reduced pyridine nucleotides and oxidized flavin, intracellular pH, and free Ca2+ were performed together with simultaneous measurement of O2 tension or removal of samples for assay of the ATP/ADP ratio. The initial changes were detected in three phases. First, decreases occurred in the ATP/ADP ratio (<3 s) and increases in pyridine (2 +/- 1 s) and flavin (2 +/- 1 s) nucleotide reduction. Next, increases in the O2 consumption rate (20 +/- 5 s), the ATP/ADP ratio (29 +/- 12 s) and internal pH (48 +/- 5 s) were observed. Finally, cytosolic free Ca2+ rose (114 +/- 10 s). Maximal changes in the ATP/ADP ratio, O2 consumption and pyridine and flavin nucleotide fluorescence preceded the beginning of the Ca2+ change. These relationships are consistent with a model in which phosphorylation of glucose is the initial event which generates the signals that lead to an increase in respiration, a rise in the ATP/ADP ratio and finally influx of Ca2+. Our results indicate that Ca2+ does not function as the initiator of increased mitochondrial respiration.

  1. Suppressive actions of betaxolol on ionic currents in retinal ganglion cells may explain its neuroprotective effects.

    PubMed

    Hirooka, K; Kelly, M E; Baldridge, W H; Barnes, S

    2000-05-01

    Betaxolol, a beta 1-selective adrenoceptor antagonist, is widely used in the treatment of glaucoma. In addition to its ocular hypotensive effects, betaxolol has been suggested to act as a retinal neuroprotective agent (Osborne et al., 1997). To investigate possible mechanisms underlying the neuroprotective effects, we tested the actions of betaxolol on ion channels and calcium signaling in isolated retinal ganglion cells. Betaxolol (50 microM) reduced by about 20% the high-voltage-activated (HVA) Ca channel currents in ganglion cells isolated from tiger salamander retina. In contrast, the beta 1-adrenoceptor antagonists propranolol (10 microM) and timolol (50 microM) had no inhibitory actions on HVA Ca channel currents. The L-type Ca channel antagonist, nisoldipine, blocked the HVA Ca channel current partially and the remaining current was not inhibited by betaxolol. Outward current was inhibited in the presence of betaxolol. Both iberiotoxin (IBTX; 10 nM), a selective inhibitor of large-conductance Ca-activated K channels, and Cd2+ (100 microM), which suppresses Ca-activated K channels subsequent to its block of Ca channels, reduced outward current and the remaining current was not blocked significantly with betaxolol. In the presence of betaxolol, Na channel currents were reduced by about 20%, as were currents evoked by glutamate (10 mM) and GABA (1 mM). Current clamp recordings from isolated ganglion cells showed that betaxolol had several effects on excitability: spike height decreased, repetitive spike activity was suppressed, spike width increased and hyperpolarization following spikes was reduced. Calcium imaging in isolated rat retinal ganglion cells revealed that betaxolol inhibited glutamate-induced increases in [Ca2+]i. These results suggest that betaxolol has a diversity of suppressive actions on ganglion cell ion channels and that, as a consequence, one of the net actions of the drug is to reduce Ca2+ influx. The subsequent reduction in [Ca2+]i may

  2. Induction of lysosomal and plasma membrane-bound sialidases in human T-cells via T-cell receptor.

    PubMed Central

    Wang, Peng; Zhang, Ji; Bian, Hong; Wu, Ping; Kuvelkar, Reshma; Kung, Ted T; Crawley, Yvette; Egan, Robert W; Billah, M Motasim

    2004-01-01

    Among the three isoenzymes of neuraminidase (Neu) or sialidase, Neu-1 has been suggested to be induced by cell activation and to be involved in IL (interleukin)-4 biosynthesis in murine T-cells. In the present study, we found that antigen-induced airway eosinophilia, a typical response dependent on Th2 (T-helper cell type 2) cytokines, as well as mRNA expression of Th2 cytokines, including IL-4, are suppressed in Neu-1-deficient mice, thereby demonstrating the in vivo role of murine Neu-1 in regulation of Th2 cytokines. To elucidate the roles of various sialidases in human T-cell activation, we investigated their tissue distribution, gene induction and function. Neu-1 is the predominant isoenzyme at the mRNA level in most tissues and cells in both mice and humans, including T-cells. T-cells also have significant levels of Neu-3 mRNAs, albeit much lower than those of Neu-1, whereas the levels of Neu-2 mRNAs are minimal. In human T-cells, both Neu-1 and Neu-3 mRNAs are significantly induced by T-cell-receptor stimulation, as is sialidase activity against 4-methylumbelliferyl- N -acetylneuramic acid (a substrate for both Neu-1 and Neu-3) and the ganglioside G(D1a) [NeuAcalpha2-3Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-4Glcbeta1-cer] (a substrate for Neu-3, but not for Neu-1). The expression of the two sialidase genes may be under differential regulation. Western blot analysis and enzymic comparison with recombinant sialidases have revealed that Neu-3 is induced as a major isoform in activated cells. The induction of Neu-1 and Neu-3 in T-cells is unique. In human monocytes and neutrophils stimulated with various agents, the only observation of sialidase induction has been by IL-1 in neutrophils. Functionally, a major difference has been observed in Jurkat T-cell lines over-expressing Neu-1- and Neu-3. Upon T-cell receptor stimulation, IL-2, interferon-gamma, IL-4 and IL-13 are induced in the Neu-1 line, whereas in the Neu-3 line the same cytokines are induced

  3. Induction of lysosomal and plasma membrane-bound sialidases in human T-cells via T-cell receptor.

    PubMed

    Wang, Peng; Zhang, Ji; Bian, Hong; Wu, Ping; Kuvelkar, Reshma; Kung, Ted T; Crawley, Yvette; Egan, Robert W; Billah, M Motasim

    2004-06-01

    Among the three isoenzymes of neuraminidase (Neu) or sialidase, Neu-1 has been suggested to be induced by cell activation and to be involved in IL (interleukin)-4 biosynthesis in murine T-cells. In the present study, we found that antigen-induced airway eosinophilia, a typical response dependent on Th2 (T-helper cell type 2) cytokines, as well as mRNA expression of Th2 cytokines, including IL-4, are suppressed in Neu-1-deficient mice, thereby demonstrating the in vivo role of murine Neu-1 in regulation of Th2 cytokines. To elucidate the roles of various sialidases in human T-cell activation, we investigated their tissue distribution, gene induction and function. Neu-1 is the predominant isoenzyme at the mRNA level in most tissues and cells in both mice and humans, including T-cells. T-cells also have significant levels of Neu-3 mRNAs, albeit much lower than those of Neu-1, whereas the levels of Neu-2 mRNAs are minimal. In human T-cells, both Neu-1 and Neu-3 mRNAs are significantly induced by T-cell-receptor stimulation, as is sialidase activity against 4-methylumbelliferyl- N -acetylneuramic acid (a substrate for both Neu-1 and Neu-3) and the ganglioside G(D1a) [NeuAcalpha2-3Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-4Glcbeta1-cer] (a substrate for Neu-3, but not for Neu-1). The expression of the two sialidase genes may be under differential regulation. Western blot analysis and enzymic comparison with recombinant sialidases have revealed that Neu-3 is induced as a major isoform in activated cells. The induction of Neu-1 and Neu-3 in T-cells is unique. In human monocytes and neutrophils stimulated with various agents, the only observation of sialidase induction has been by IL-1 in neutrophils. Functionally, a major difference has been observed in Jurkat T-cell lines over-expressing Neu-1- and Neu-3. Upon T-cell receptor stimulation, IL-2, interferon-gamma, IL-4 and IL-13 are induced in the Neu-1 line, whereas in the Neu-3 line the same cytokines are induced

  4. Ionic Mechanisms of Microsecond-Scale Spike Timing in Single Cells

    PubMed Central

    Zakon, Harold H.

    2014-01-01

    Electric fish image their environments and communicate by generating electric organ discharges through the simultaneous action potentials (APs) of electric organ cells (electrocytes) in the periphery. Steatogenys elegans generates a biphasic electrocyte discharge by the precisely regulated timing and waveform of APs generated from two excitable membranes present in each electrocyte. Current-clamp recordings of electrocyte APs reveal that the posterior membrane fires first, followed ∼30 μs later by an AP on the anterior membrane. This delay was maintained even as the onset of the first AP was advanced >5 ms by increasing stimulus intensity and across multiple spikes during bursts of APs elicited by prolonged stimulation. Simultaneous cell-attached loose-patch recordings of Na+ currents on each membrane revealed that activation voltage for Na+ channels on the posterior membrane was 10 mV hyperpolarized compared with Na+ channels on the anterior membrane, with no differences in activation or inactivation kinetics. Computational simulations of electrocyte APs demonstrated that this difference in Na+ current activation voltage was sufficient to maintain the proper firing order and the interspike delay. A similar difference in activation threshold has been reported for the Na+ currents of the axon initial segment compared with somatic Na+ channels of pyramidal neurons, suggesting convergent evolution of spike initiation and timing mechanisms across different systems of excitable cells. PMID:24806692

  5. Electrophysiological characterization of ionic transport by the retinal exchanger expressed in human embryonic kidney cells.

    PubMed Central

    Navanglone, A; Rispoli, G; Gabellini, N; Carafoli, E

    1997-01-01

    The retinal Na+:Ca2+, K+exchanger cDNA was transiently expressed in human embryonic kidney (HEK 293) cells by transfection with plasmid DNA. The correct targeting of the expressed protein to the plasma membrane was confirmed by immunocytochemistry. The reverse exchange offrent (Ca2+ imported per Na+ extruded) was measured in whole-cell voltage-clamp experiments after intracellular perfusion with Na+ (Na+i, 128 mM) and extracellular perfusion with Ca2+ (Ca2o+, 1 mM) and Ko+ (20 mM). As expected, the exchange current was suppressed by removing Ca2o+. Surprisingly, however, it was also abolished by increasing Na+o to almost abolish the Na+ gradient, and it was almost unaffected by the removal of Ko+. Apparently, then, at variance with the exchanger in the rod outer segment, the retinal exchanger expressed in 293 cells acts essentially as a Na+:Ca2+ exchanger and does not require K+ for its electrogenic activity. Images FIGURE 1 PMID:9199770

  6. Neuronal Cell Patterning on Covalently Bound Protein Patterns by Micro-Contact Printing Techniques and the Functioning of Proteins Bound on Silane Monolayers

    DTIC Science & Technology

    2004-12-01

    Buttler, J.E., Ni, L ., Brown, W.R., Joshi, K.S., Cha g , J., n Rosenberg, B., and Voss, Jr. E.W., 1993: The Immunochemistry of Sandwich Elisas—VI...CONTRACT NUMBER g 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING...biotin, lectins, protein A and protein G , and a fragment of specific antibodies. We believe that the patterns of neuronal cells on the protein

  7. In vivo invasion of modified chorioallantoic membrane by tumor cells: the role of cell surface-bound urokinase

    PubMed Central

    1988-01-01

    The ability of the chick embryo chorioallantoic membrane (CAM) to withstand invasion by tumor cells can be intentionally compromised by altering its morphological integrity. Using a newly developed quantitative assay of invasion we showed that intact CAMs were completely resistant to invasion by tumor cells, wounded CAMs did not pose a barrier to penetration, and CAMs that were wounded and then allowed to reseal displayed partial susceptibility to invasion. The invasion of resealed CAMs required catalytically active plasminogen activator (PA) of the urokinase type (uPA); the invasive efficiency of tumor cells was reduced by 75% when tumor uPA activity or tumor uPA production was inhibited. The invasive ability of human tumor cells, which have surface uPA receptors but which do not produce the enzyme, could be augmented by saturating their receptors with exogenous uPA. The mere stimulation of either uPA or tissue plasminogen activator production, in absence of binding to cell receptors, did not result in an enhancement of invasiveness. These findings suggest that the increased invasive potential of tumor cells is correlated with cell surface-associated proteolytic activity stemming from the interaction between uPA and its surface receptor. PMID:2848851

  8. Engineered microorganisms having resistance to ionic liquids

    SciTech Connect

    Ruegg, Thomas Lawrence; Thelen, Michael P.

    2016-03-22

    The present invention provides for a method of genetically modifying microorganisms to enhance resistance to ionic liquids, host cells genetically modified in accordance with the methods, and methods of using the host cells in a reaction comprising biomass that has been pretreated with ionic liquids.

  9. Study of Mast Cells and Granules from Primo Nodes Using Scanning Ionic Conductance Microscopy.

    PubMed

    Yoo, Yeong-Yung; Jung, Goo-Eun; Kwon, Hee-Min; Bae, Kyoung-Hee; Cho, Sang-Joon; Soh, Kwang-Sup

    2015-12-01

    Acupuncture points have a notable characteristic in that they have a higher density of mast cells (MCs) compared with nonacupoints in the skin, which is consistent with the augmentation of the immune function by acupuncture treatment. The primo vascular system, which was proposed as the anatomical structure of the acupuncture points and meridians, also has a high density of MCs. We isolated the primo nodes from the surfaces of internal abdominal organs, and the harvested primo nodes were stained with toluidine blue. The MCs were easily recognized by their stained color and their characteristic granules. The MCs were classified into four stages according to the degranulation of histamine granules in the MCs. Using conventional optical microscopes details of the degranulation state of MCs in each stage were not observable. However, we were able to investigate the distribution of the granules on the surfaces of the MCs in each stage, and to demonstrate the height profiles and three-dimensional structures of the MCs without disturbance of the cell membrane by using the scanning ion conductance microscopy.

  10. Ionic conductivity in PEO-KOH polymer electrolytes and electrochemical cell performance

    NASA Astrophysics Data System (ADS)

    Hassan, M. F.; Arof, A. K.

    2005-10-01

    Polyethylene oxide (PEO) and potassium hydroxide (KOH) alkaline solid polymer electrolytes were prepared by the solution cast technique. The PEO:KOH wt% ratio in the alkaline solid polymer electrolyte system which exhibits the highest room temperature conductivity is 60:40. The conductivity was 3.10 × 10-5 S cm-1. X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) were used to study the characteristics of the PEO polymer electrolyte films. The Rice and Roth model was used to evaluate the number density of charge carriers. Knowing the number density of charge carriers enabled the mobility and diffusion coefficient to be calculated. An all solid-state Ni(OH)2/MH rechargeable metal hydride cell has been fabricated using the highest conducting PEO-KOH alkaline solid polymer electrolyte. The cell was charged at a constant current of 2 mA and discharged at 0.5 mA. The discharge characteristics improved upon cycling and the plateau voltage maintained above 1.3 V for more than 2 hours during the 16th cycle.

  11. Archaea-based microbial fuel cell operating at high ionic strength conditions.

    PubMed

    Abrevaya, Ximena C; Sacco, Natalia; Mauas, Pablo J D; Cortón, Eduardo

    2011-11-01

    In this work, two archaea microorganisms (Haloferax volcanii and Natrialba magadii) used as biocatalyst at a microbial fuel cell (MFC) anode were evaluated. Both archaea are able to grow at high salt concentrations. By increasing the media conductivity, the internal resistance was diminished, improving the MFC's performance. Without any added redox mediator, maximum power (P (max)) and current at P (max) were 11.87/4.57/0.12 μW cm(-2) and 49.67/22.03/0.59 μA cm(-2) for H. volcanii, N. magadii and E. coli, respectively. When neutral red was used as the redox mediator, P (max) was 50.98 and 5.39 μW cm(-2) for H. volcanii and N. magadii, respectively. In this paper, an archaea MFC is described and compared with other MFC systems; the high salt concentration assayed here, comparable with that used in Pt-catalyzed alkaline hydrogen fuel cells, will open new options when MFC scaling up is the objective necessary for practical applications.

  12. The flow of red blood cells in stenosed microvessels and the influence of red blood cells on wall-bounded rolling motion of microparticles

    NASA Astrophysics Data System (ADS)

    Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit

    2015-11-01

    In the first part of this work, we consider a 3D computational study of the flow of deformable red blood cells in stenosed microvessels. We observe that the apparent viscosity of blood increases by several folds, and the rate of increase with increasing vessel diameter is also higher than that in non-stenosed vessels, implying an enhancement of the well-known Fahraeus-Lindqvist effect. The flow of the red blood cells causes time-dependent fluctuations in the blood flow rate. The RMS of the flow rate oscillations in the stenosed vessel is observed to be significantly higher than that in the non-stenosed vessel. Furthermore, several folds increase in the Eulerian velocity fluctuations and a transient flow reversal upstream the stenosed region are also observed, which would not occur in absence of the cells. In the second part, we consider the adhesive rolling motion of wall-bounded microparticles in presence of flowing red blood cells in microvessels. We observe two contradictory role of the red blood cells: On one hand, the cells facilitate the establishment of the particle-wall contact, and, thereby, initiation of adhesion. On the other hand, they augment the rolling velocity of the particles. Implications of these results on the optimal design of drug carriers are discussed.

  13. Regulatory role of membrane-bound form interleukin-15 on human uterine microvascular endothelial cells in circulating CD16(-) natural killer cell extravasation into human endometrium.

    PubMed

    Kitaya, Kotaro; Yasuo, Tadahiro

    2013-09-01

    Interleukin (IL)-15 plays a major role in accumulation of unique CD16(-) natural killer (NK) cells in the human endometrium, partly via selective extravasation of peripheral blood (PB) counterparts from local microvascular circulation. While IL-15 exhibits a chemotactic activity for PB CD16(-) NK cells, IL-15 attenuates their binding capacity to dermatan sulfate, the major CD62L ligand expressed on human uterine microvascular endothelial cells (HUtMVECs). These findings suggest that premature action of IL-15 interferes with CD62L-dependent tethering/rolling of PB CD16(-) NK cells on HUtMVECs, which is an early critical process of leukocyte extravasation. In this study, we investigated the mechanisms underlying the IL-15 regulation in the initial CD62L-dependent contact between PB CD16(-) NK cells and HUtMVECs. Unlike other candidate molecules, recombinant IL-15 downregulated CD62L expression on freshly isolated PB CD16(-) NK cells. IL-12 and IL-10, the two known upregulators of CD62L on CD16(-) NK cells, were not detectable in HUtMVECs and endometrial perivascular stromal cells. Binding to immobilized dermatan sulfate increased surface IL-15 receptor-alpha chain expression on CD16(-) NK cells. Under ovarian steroid stimulation, IL-15 was detectable on the surface, but not in the supernatant, of cultured HUtMVECs. Ovarian steroid-induced IL-15 expression on HUtMVECs was not attenuated by chondroitinase ABC (which degrades chondroitin sulfate-A and -C and dermatan sulfate) or sodium acetate buffer (which dissociates cytokines from their cognate receptors). These results suggest that HUtMVECs secrete a less soluble form of IL-15 into local microcirculation. Instead, HUtMVECs bear a membrane-bound form IL-15 under the influence of ovarian steroids, which may be favorable for preventing downregulation of CD62L on PB CD16(-) NK cells and facilitating their initial contact with HUtMVECs.

  14. Super ionic conductive glass

    DOEpatents

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  15. Super ionic conductive glass

    DOEpatents

    Susman, Sherman; Volin, Kenneth J.

    1984-01-01

    An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  16. Modes of Diffusion of Cholera Toxin Bound to GM1 on Live Cell Membrane by Image Mean Square Displacement Analysis

    PubMed Central

    Moens, Pierre D.J.; Digman, Michelle A.; Gratton, Enrico

    2015-01-01

    The image-mean square displacement technique applies the calculation of the mean square displacement commonly used in single-molecule tracking to images without resolving single particles. The image-mean square displacement plot obtained is similar to the mean square displacement plot obtained using the single-particle tracking technique. This plot is then used to reconstruct the protein diffusion law and to identify whether the labeled molecules are undergoing pure isotropic, restricted, corralled, transiently confined, or directed diffusion. In our study total internal reflection fluorescence microscopy images were taken of Cholera toxin subunit B (CtxB) membrane-labeled NIH 3T3 mouse fibroblasts and MDA 231 MB cells. We found a population of CTxB undergoing purely isotropic diffusion and one displaying restricted diffusion with corral sizes ranging from 150 to ∼1800 nm. We show that the diffusion rate of CTxB bound to GM1 is independent of the size of the confinement, suggesting that the mechanism of confinement is different from the mechanism controlling the diffusion rate of CtxB. We highlight the potential effect of continuous illumination on the diffusion mode of CTxB. We also show that aggregation of CTxB/GM1 in large complexes occurs and that these aggregates tend to have slower diffusion rates. PMID:25809257

  17. Purification and characterization of two new cell-bound bioactive compounds produced by wild Lactococcus lactis strain.

    PubMed

    Saraiva, Margarete Alice Fontes; Brede, Dag Anders; Nes, Ingolf Figved; Baracat-Pereira, Maria Cristina; de Queiroz, Marisa Vieira; de Moraes, Célia Alencar

    2017-07-03

    Novel compounds and innovative methods are required considering that antibiotic resistance has reached a crisis point. In the study, two cell-bound antimicrobial compounds produced by Lactococcus lactis ID1.5 were isolated and partially characterized. Following purification by cationic exchange and a solid-phase C18 column, antimicrobial activity was recovered after three runs of RPC using 60% (v/v) and 100% (v/v) of 2-propanol for elution, suggesting that more than one antimicrobial compound were produced by L. lactis ID1.5, which were in this study called compounds AI and AII. The mass spectrum of AI and AII showed major intensity ions at m/z 1070.05 and 955.9 Da, respectively. The compound AI showed a spectrum of antimicrobial activity mainly against L. lactis species, while the organisms most sensitive to compound AII were Bacillus subtilis, Listeria innocua, Streptococcus pneumoniae and Pseudomonas aeruginosa. The antimicrobial activity of both compounds was suppressed by treatment with Tween 80. Nevertheless, both compounds showed high stability to heat and proteases treatments. The isolated compounds, AI and AII, showed distinct properties from other antimicrobial substances already reported as produced by L. lactis, and have a significant inhibitory effect against two clinically important respiratory pathogens. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Modes of diffusion of cholera toxin bound to GM1 on live cell membrane by image mean square displacement analysis.

    PubMed

    Moens, Pierre D J; Digman, Michelle A; Gratton, Enrico

    2015-03-24

    The image-mean square displacement technique applies the calculation of the mean square displacement commonly used in single-molecule tracking to images without resolving single particles. The image-mean square displacement plot obtained is similar to the mean square displacement plot obtained using the single-particle tracking technique. This plot is then used to reconstruct the protein diffusion law and to identify whether the labeled molecules are undergoing pure isotropic, restricted, corralled, transiently confined, or directed diffusion. In our study total internal reflection fluorescence microscopy images were taken of Cholera toxin subunit B (CtxB) membrane-labeled NIH 3T3 mouse fibroblasts and MDA 231 MB cells. We found a population of CTxB undergoing purely isotropic diffusion and one displaying restricted diffusion with corral sizes ranging from 150 to ∼1800 nm. We show that the diffusion rate of CTxB bound to GM1 is independent of the size of the confinement, suggesting that the mechanism of confinement is different from the mechanism controlling the diffusion rate of CtxB. We highlight the potential effect of continuous illumination on the diffusion mode of CTxB. We also show that aggregation of CTxB/GM1 in large complexes occurs and that these aggregates tend to have slower diffusion rates. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Purification and reconstitution of human membrane-bound DHRS7 (SDR34C1) from Sf9 cells.

    PubMed

    Skarka, Adam; Škarydová, Lucie; Štambergová, Hana; Wsól, Vladimír

    2014-03-01

    Dehydrogenase/reductase SDR family member 7 (DHRS7, SDR34C1, retSDR4) is one of the many endoplasmic reticulum bound members of the SDR superfamily. Preliminary results indicate its potential significance in human metabolism. DHRS7 containing TEV-cleavable His10 and FLAG-tag expressed in the Sf9 cell line was solubilised, purified, and reconstituted into liposomes to enable the improved characterisation of this enzyme in the future. Igepal CA-630 was determined to be the best detergent for the solubilisation process. The solubilised DHRS7 was purified using affinity chromatography, and the purified enzyme was subjected to TEV cleavage of the affinity tags and then repurified using subtractive Ni-IMAC. The cleaved and uncleaved versions of DHRS7 were successfully reconstituted into liposomes. In addition, using tobacco specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) as the substrate, the cleaved liposomal DHRS7 was found to be inactive, whereas the pure and uncleaved liposomal DHRS7 were confirmed as enzymes, which reduce carbonyl group of the substrates.

  20. Protein-Bound Polysaccharide from Corbicula fluminea Inhibits Cell Growth in MCF-7 and MDA-MB-231 Human Breast Cancer Cells

    PubMed Central

    Liao, Ningbo; Zhong, Jianjun; Zhang, Ronghua; Ye, Xingqian; Zhang, Yanjun; Wang, Wenjun; Wang, Yuexia; Chen, Shiguo; Liu, Donghong; Liu, Ruihai

    2016-01-01

    A novel protein-bound polysaccharide, CFPS-1, isolated from Corbicula fluminea, is composed predominantly of mannose (Man) and glucose (Glc) in a molar ratio of 3.1:12.7. The polysaccharide, with an average molecular weight of about 283 kDa, also contains 10.8% protein. Atomic force microscopy, high-performance liquid chromatography, Fourier transform infrared spectroscopy, gas chromatography/mass spectrometry, and nuclear magnetic resonance spectroscopy analyses revealed that CFPS-1 has a backbone of 1,6-linked and 1,4,6-linked-α-D-Glc, which is terminated with a 1-linked-α-D-Man residue at the O-4 position of 1,4,6-linked-α-D-Glc, in a molar ratio of 3:1:1. Preliminary in vitro bioactivity tests revealed that CFPS-1 effectively and dose-dependently inhibits human breast cancer MCF-7 and MDA-MB-231 cell growth, with an IC50 of 243 ± 6.79 and 1142 ± 14.84 μg/mL, respectively. In MCF-7, CFPS-1 produced a significant up-regulation of p53, p21, Bax and cleaved caspase-7 and down-regulation of Cdk4, cyclin D1, Bcl-2 and caspase-7. These effects resulted in cell cycle blockade at the S-phase and apoptosis induction. In contrast, in MDA-MB-231, with limited degree of change in cell cycle distribution, CFPS-1 increases the proportion of cells in apoptotic sub-G1 phase executed by down-regulation of Bcl-2 and caspase-7 and up-regulation of Bax and cleaved caspase-7. This study extends our understanding of the anticancer mechanism of C. fluminea protein-bound polysaccharide. PMID:27959954

  1. Ionic Conductivity and Potential Application for Fuel Cell of a Modified Imine-Based Covalent Organic Framework.

    PubMed

    Montoro, Carmen; Rodríguez-San-Miguel, David; Polo, Eduardo; Escudero-Cid, Ricardo; Ruiz-González, Maria Luisa; Navarro, Jorge A R; Ocón, Pilar; Zamora, Félix

    2017-07-26

    We present the novel potential application of imine-based covalent organic frameworks (COFs), formed by the direct Schiff reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde building blocks in m-cresol or acetic acid, named RT-COF-1 or RT-COF-1Ac/RT-COF-1AcB. The post-synthetic treatment of RT-COF-1 with LiCl leads to the formation of LiCl@RT-COF-1. The ionic conductivity of this series of polyimine COFs has been characterized at variable temperature and humidity, using electrochemical impedance spectroscopy. LiCl@RT-COF-1 exhibits a conductivity value of 6.45 × 10(-3) S cm(-1) (at 313 K and 100% relative humidity) which is among the highest values so far reported in proton conduction for COFs. The mechanism of conduction has been determined using (1)H and (7)Li solid-state nuclear magnetic resonance spectroscopy. Interestingly, these materials, in the presence of controlled amounts of acetic acid and under pressure, show a remarkable processability that gives rise to quasi-transparent and flexible films showing in-plane structural order as confirmed by X-ray crystallography. Finally, we prove that these films are useful for the construction of proton exchange membrane fuel cells (PEMFC) reaching values up to 12.95 mW cm(-2) and 53.1 mA cm(-2) for maximum power and current density at 323 K, respectively.

  2. Solution-Processable Ionic Liquid as an Independent or Modifying Electron Transport Layer for High-Efficiency Perovskite Solar Cells.

    PubMed

    Wu, Qiliang; Zhou, Weiran; Liu, Qing; Zhou, Pengcheng; Chen, Tao; Lu, Yalin; Qiao, Qiquan; Yang, Shangfeng

    2016-12-21

    Inorganic metal oxide, especially TiO2, has been commonly used as an electron transport layer (ETL) in regular-structure (n-i-p) planar heterojunction perovskite solar cells (PHJ-PSCs) but generally suffers from high electron recombination rate and incompatibility with low-temperature solution processability. Herein, by applying an ionic liquid (IL, 1-ethyl-3-methylimidazolium hexafluorophosphate ([EMIM]PF6)) as either a TiO2-modifying interlayer or an independent ETL, we investigated systematically IL interface engineering for PHJ-PSCs. Upon spin-coating [EMIM]PF6-IL onto TiO2 ETL as a modification layer, the average power conversion efficiency (PCE) of CH3NH3PbI3 PHJ-PSC devices reaches 18.42 ± 0.65%, which dramatically surpasses that based on commonly used TiO2 ETL (14.20 ± 0.43%), and the highest PCE (19.59%) is almost identical to that of the record PCE for planar CH3NH3PbI3 PSCs (19.62%) reported very recently. On the other hand, by applying [EMIM]PF6-IL as an independent ETL, we achieved an average PCE of 13.25 ± 0.55%, and the highest PCE (14.39%) approaches that obtained for PHJ-PSCs based on independent TiO2 ETL (14.96%). Both IL interface engineering methods reveal the effective electron transport of [EMIM]PF6-IL. The effects of [EMIM]PF6-IL on the surface morphology, crystallinity, and optical absorption of the perovskite film and the interface between the perovskite layer and substrate were investigated and compared with the case of independent TiO2 ETL, revealing the role of [EMIM]PF6-IL in efficient electron transport.

  3. Structure Analysis and Conformational Transitions of the Cell Penetrating Peptide Transportan 10 in the Membrane-Bound State

    PubMed Central

    Strandberg, Erik; Verdurmen, Wouter P. R.; Bürck, Jochen; Ehni, Sebastian; Mykhailiuk, Pavel K.; Afonin, Sergii; Gerthsen, Dagmar; Komarov, Igor V.; Brock, Roland; Ulrich, Anne S.

    2014-01-01

    Structure analysis of the cell-penetrating peptide transportan 10 (TP10) revealed an exemplary range of different conformations in the membrane-bound state. The bipartite peptide (derived N-terminally from galanin and C-terminally from mastoparan) was found to exhibit prominent characteristics of (i) amphiphilic α-helices, (ii) intrinsically disordered peptides, as well as (iii) β-pleated amyloid fibrils, and these conformational states become interconverted as a function of concentration. We used a complementary approach of solid-state 19F-NMR and circular dichroism in oriented membrane samples to characterize the structural and dynamical behaviour of TP10 in its monomeric and aggregated forms. Nine different positions in the peptide were selectively substituted with either the L- or D-enantiomer of 3-(trifluoromethyl)-bicyclopent-[1.1.1]-1-ylglycine (CF3-Bpg) as a reporter group for 19F-NMR. Using the L-epimeric analogs, a comprehensive three-dimensional structure analysis was carried out in lipid bilayers at low peptide concentration, where TP10 is monomeric. While the N-terminal region is flexible and intrinsically unstructured within the plane of the lipid bilayer, the C-terminal α-helix is embedded in the membrane with an oblique tilt angle of ∼55° and in accordance with its amphiphilic profile. Incorporation of the sterically obstructive D-CF3-Bpg reporter group into the helical region leads to a local unfolding of the membrane-bound peptide. At high concentration, these helix-destabilizing C-terminal substitutions promote aggregation into immobile β-sheets, which resemble amyloid fibrils. On the other hand, the obstructive D-CF3-Bpg substitutions can be accommodated in the flexible N-terminus of TP10 where they do not promote aggregation at high concentration. The cross-talk between the two regions of TP10 thus exerts a delicate balance on its conformational switch, as the presence of the α-helix counteracts the tendency of the unfolded N

  4. Positive Root Bounds and Root Separation Bounds

    NASA Astrophysics Data System (ADS)

    Herman, Aaron Paul

    In this thesis, we study two classes of bounds on the roots of a polynomial (or polynomial system). A positive root bound of a polynomial is an upper bound on the largest positive root. A root separation bound of a polynomial is a lower bound on the distance between the roots. Both classes of bounds are fundamental tools in computer algebra and computational real algebraic geometry, with numerous applications. In the first part of the thesis, we study the quality of positive root bounds. Higher quality means that the relative over-estimation (the ratio of the bound and the largest positive root) is smaller. We find that all known positive root bounds can be arbitrarily bad. We then show that a particular positive root bound is tight for certain important classes of polynomials. In the remainder of the thesis, we turn to root separation bounds. We observe that known root separation bounds are usually very pessimistic. To our surprise, we also find that known root separation bounds are not compatible with the geometry of the roots (unlike positive root bounds). This motivates us to derive new root separation bounds. In the second part of this thesis, we derive a new root separation for univariate polynomials by transforming a known bound into a new improved bound. In the third part of this thesis, we use a similar strategy to derive a new improved root separation bound for polynomial systems.

  5. Macrophage uptake of low-density lipoprotein bound to aggregated C-reactive protein: possible mechanism of foam-cell formation in atherosclerotic lesions.

    PubMed Central

    Fu, Tao; Borensztajn, Jayme

    2002-01-01

    Foam cells found in atherosclerotic lesions are believed to derive from macrophages that take up aggregated low-density lipoprotein (LDL) particles bound to the extracellular matrix of arterial walls. C-reactive protein (CRP) is an acute-phase protein found in atherosclerotic lesions, which when immobilized on a solid phase, can bind and cluster LDL particles in a calcium-dependent manner. In the present study, we examined whether CRP-bound aggregated LDL could be taken up by macrophages in culture. CRP molecules were aggregated in the presence of calcium and immobilized on the surface of polystyrene microtitre wells. Human LDL added to the wells bound to and aggregated on the immobilized CRP, also in a calcium-dependent manner. On incubation with macrophages, the immobilized CRP-bound LDL aggregates were readily taken up by the cells, as demonstrated by immunofluorescence microscopy, by the cellular accumulation of cholesterol and by the overexpression of adipophilin. Immunofluorescence microscopy and flow-cytometry analysis established that the uptake of the LDL-CRP complex was not mediated by the CRP receptor CD32. These observations with immobilized CRP and LDL, approximating the conditions that exist in the extracellular matrix of the arterial wall, thus suggest that CRP may contribute to the formation of foam cells in atherosclerotic lesions by causing the aggregation of LDL molecules that are then taken up by macrophages through a CD32-independent pathway. PMID:12033985

  6. The Autocrine Mitogenic Loop of the Ciliate Euplotes raikovi: The Pheromone Membrane-bound Forms Are the Cell Binding Sites and Potential Signaling Receptors of Soluble Pheromones

    PubMed Central

    Ortenzi, Claudio; Alimenti, Claudio; Vallesi, Adriana; Di Pretoro, Barbara; Terza, Antonietta La; Luporini, Pierangelo

    2000-01-01

    Homologous proteins, denoted pheromones, promote cell mitotic proliferation and mating pair formation in the ciliate Euplotes raikovi, according to whether they bind to cells in an autocrine- or paracrine-like manner. The primary transcripts of the genes encoding these proteins undergo alternate splicing, which generates at least two distinct mRNAs. One is specific for the soluble pheromone, the other for a pheromone isoform that remains anchored to the cell surface as a type II protein, whose extracellular C-terminal region is structurally equivalent to the secreted form. The 15-kDa membrane-bound isoform of pheromone Er-1, denoted Er-1mem and synthesized by the same E. raikovi cells that secrete Er-1, has been purified from cell membranes by affinity chromatography prepared with matrix-bound Er-1, and its extracellular and cytoplasmic regions have been expressed as recombinant proteins. Using the purified material and these recombinant proteins, it has been shown that Er-1mem has the property of binding pheromones competitively through its extracellular pheromone-like domain and associating reversibly and specifically with a guanine nucleotide-binding protein through its intracellular domain. It has been concluded that the membrane-bound pheromone isoforms of E. raikovi represent the cell effective pheromone binding sites and are functionally equipped for transducing the signal generated by this binding. PMID:10749941

  7. Rational design of mixed ionic and electronic conducting perovskite oxides for solid oxide fuel cell anode materials: A case study for doped SrTiO3

    SciTech Connect

    Suthirakun, Suwit; Xiao, Guoliang; Ammal, Salai Cheettu; Chen, Fanglin; zur Loye, Hans-Conrad; Heyden, Andreas

    2014-01-01

    The effect of p- and n-type dopants on ionic and electronic conductivity of SrTiO3 based perovskites were investigated both computationally and experimentally. Specifically, we performed density functional theory (DFT) calculations of Na- and La-doped SrTiO3 and Na- and Nb-doped SrTiO3 systems. Constrained ab initio thermodynamic calculations were used to evaluate the phase stability and reducibility of doped SrTiO3 under both oxidizing and reducing synthesis conditions, as well as under anodic solid oxide fuel cell (SOFC) conditions. The density of states (DOS) of these materials was analyzed to study the effects of p- and n-doping on the electronic conductivity. Furthermore, Na- and La-doped SrTiO3 and Na- and Nb-doped SrTiO3 samples were experimentally prepared and the conductivity was measured to confirm our computational predictions. The experimental observations are in very good agreement with the theoretical predictions that doping n-doped SrTiO3 with small amounts of p-type dopants promotes both the ionic and electronic conductivity of the material. This doping strategy is valid independent of p- and n-doping site and permits the synthesis of perovskite based mixed ionic/electronic conductors.

  8. Cycling and rate performance of Li-LiFePO 4 cells in mixed FSI-TFSI room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Lewandowski, A. P.; Hollenkamp, A. F.; Donne, S. W.; Best, A. S.

    A study is conducted of the performance of lithium iron(II) phosphate, LiFePO 4, as a cathode material in a lithium secondary battery that features an ionic liquid electrolyte solution and a metallic lithium anode. The electrolyte solution comprises an ionic liquid of a N-methyl-N-alkyl-pyrrolidinium (alkyl = n-propyl or n-butyl) cation and either the bis(fluorosulfonyl)imide [(FSO 2) 2N -] or bis(trifluoromethanesulfonyl)imide [(F 3CSO 2) 2N -] anion, together with 0.5 mol kg -1 of lithium bis(trifluoromethanesulfonyl)imide salt. For N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide, coin cells discharging at rates of C/10 and 4C yield specific capacities of 153 and 110 mAh g -1, respectively, at an average coulombic efficiency of 99.8%. This performance is maintained for over 400 cycles at 50 °C and therefore indicates that these electrolyte solutions support long-term cycling of both LiFePO 4 and metallic lithium while, due to the negligible volatility of ionic liquids, surrounding the lithium in an inherently safe, non-flammable medium.

  9. Ionic Liquids Database- (ILThermo)

    National Institute of Standards and Technology Data Gateway

    SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

  10. Thermotropic Ionic Liquid Crystals

    PubMed Central

    Axenov, Kirill V.; Laschat, Sabine

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed. PMID:28879986

  11. The Avise Lupus Test and Cell-bound Complement Activation Products Aid the Diagnosis of Systemic Lupus Erythematosus

    PubMed Central

    Mossell, James; Goldman, John A.; Barken, Derren; Alexander, Roberta Vezza

    2016-01-01

    Background: Systemic lupus erythematosus (SLE) is a multifaceted disease, and its diagnosis may be challenging. A blood test for the diagnosis of SLE, the Avise Lupus test, has been recently commercialized and validated in clinical studies. Objectives: To evaluate the use of the Avise Lupus test by community rheumatologists. Methods: The study is a longitudinal, case-control, retrospective review of medical charts. Cases had a positive test result, and controls had a negative result; all patients were anti-nuclear antibodies (ANA) positive but negative for SLE-specific autoantibodies. Features of SLE, diagnosis, and medications at two time points were recorded. Results: Twenty of the 23 cases (87%) and 4 of the 23 controls (17%) were diagnosed with SLE (sensitivity=83%; specificity=86%). More cases than controls (43% vs. 17%) fulfilled 4 American College of Rheumatology (ACR) classification criteria of SLE. Sensitivity of the test was significantly higher than the ACR score (83% vs. 42%, p=0.006). A higher percentage of patients who met the classification criteria had elevated cell-bound complement activation products (CB-CAPs) compared to patients who did not. Anti-rheumatic medications were used in a higher percentage of cases than controls (83% vs. 35% at baseline, p=0.002), suggesting that cases were treated more aggressively early on. Conclusion: A positive Avise Lupus test result aids in formulating a SLE diagnosis when diagnosis based on standard-of-care tests and clinical features may be challenging, and impacts patient management. Prospective studies will be performed to better evaluate the clinical utility of the test and of CB-CAPs as biomarkers of SLE. PMID:27867431

  12. First principles approach to ionicity of fragments

    NASA Astrophysics Data System (ADS)

    Pilania, Ghanshyam; Liu, Xiang-Yang; Valone, Steven M.

    2015-02-01

    We develop a first principles approach towards the ionicity of fragments. In contrast to the bond ionicity, the fragment ionicity refers to an electronic property of the constituents of a larger system, which may vary from a single atom to a functional group or a unit cell to a crystal. The fragment ionicity is quantitatively defined in terms of the coefficients of contributing charge states in a superposition of valence configurations of the system. Utilizing the constrained density functional theory-based computations, a practical method to compute the fragment ionicity from valence electron charge densities, suitably decomposed according to the Fragment Hamiltonian (FH) model prescription for those electron densities, is presented for the first time. The adopted approach is illustrated using BeO, MgO and CaO diatomic molecules as simple examples. The results are compared and discussed with respect to the bond ionicity scales of Phillips and Pauling.

  13. Potato lectin activates basophils and mast cells of atopic subjects by its interaction with core chitobiose of cell-bound non-specific immunoglobulin E

    PubMed Central

    Pramod, S N; Venkatesh, Y P; Mahesh, P A

    2007-01-01

    A major factor in non-allergic food hypersensitivity could be the interaction of dietary lectins with mast cells and basophils. Because immunoglobulin E (IgE) contains 10–12% carbohydrates, lectins can activate and degranulate these cells by cross-linking the glycans of cell-bound IgE. The present objective focuses on the effect of potato lectin (Solanum tuberosum agglutinin; STA) for its ability to release histamine from basophils in vitro and mast cells in vivo from non-atopic and atopic subjects. In this study, subjects were selected randomly based on case history and skin prick test responses with food, pollen and house dust mite extracts. Skin prick test (SPT) was performed with STA at 100 µg/ml concentration. Histamine release was performed using leucocytes from non-atopic and atopic subjects and rat peritoneal exudate cells. SPT on 110 atopic subjects using STA showed 39 subjects positive (35%); however, none showed STA-specific IgE; among 20 non-atopic subjects, none were positive by SPT. Maximal histamine release was found to be 65% in atopic subjects (n = 7) compared to 28% in non-atopic subjects (n = 5); the release was inhibited specifically by oligomers of N-acetylglucosamine and correlates well with serum total IgE levels (R2 = 0·923). Binding of STA to N-linked glycoproteins (horseradish peroxidase, avidin and IgG) was positive by dot blot and binding assay. As potato lectin activates and degranulates both mast cells and basophils by interacting with the chitobiose core of IgE glycans, higher intake of potato may increase the clinical symptoms as a result of non-allergic food hypersensitivity in atopic subjects. PMID:17362264

  14. Ionic channel mechanisms mediating the intrinsic excitability of Kenyon cells in the mushroom body of the cricket brain.

    PubMed

    Inoue, Shigeki; Murata, Kaoru; Tanaka, Aiko; Kakuta, Eri; Tanemura, Saori; Hatakeyama, Shiori; Nakamura, Atsunao; Yamamoto, Chihiro; Hasebe, Masaharu; Kosakai, Kumiko; Yoshino, Masami

    2014-09-01

    Intrinsic neurons within the mushroom body of the insect brain, called Kenyon cells, play an important role in olfactory associative learning. In this study, we examined the ionic mechanisms mediating the intrinsic excitability of Kenyon cells in the cricket Gryllus bimaculatus. A perforated whole-cell clamp study using β-escin indicated the existence of several inward and outward currents. Three types of inward currents (INaf, INaP, and ICa) were identified. The transient sodium current (INaf) activated at -40 mV, peaked at -26 mV, and half-inactivated at -46.7 mV. The persistent sodium current (INaP) activated at -51 mV, peaked at -23 mV, and half-inactivated at -30.7 mV. Tetrodotoxin (TTX; 1 μM) completely blocked both INaf and INaP, but 10nM TTX blocked INaf more potently than INaP. Cd(2+) (50 μM) potently blocked INaP with little effect on INaf. Riluzole (>20 μM) nonselectively blocked both INaP and INaf. The voltage-dependent calcium current (ICa) activated at -30 mV, peaked at -11.3 mV, and half-inactivated at -34 mV. The Ca(2+) channel blocker verapamil (100 μM) blocked ICa in a use-dependent manner. Cell-attached patch-clamp recordings showed the presence of a large-conductance Ca(2+)-activated K(+) (BK) channel, and the activity of this channel was decreased by removing the extracellular Ca(2+) or adding verapamil or nifedipine, and increased by adding the Ca(2+) agonist Bay K8644, indicating that Ca(2+) entry via the L-type Ca(2+) channel regulates BK channel activity. Under the current-clamp condition, membrane depolarization generated membrane oscillations in the presence of 10nM TTX or 100 μM riluzole in the bath solution. These membrane oscillations disappeared with 1 μM TTX, 50 μM Cd(2+), replacement of external Na(+) with choline, and blockage of Na(+)-activated K(+) current (IKNa) with 50 μM quinidine, indicating that membrane oscillations are primarily mediated by INaP in cooperation with IKNa. The plateau potentials observed either in

  15. A higher performance dye-sensitized solar cell based on the modified PMII/EMIMBF4 binary room temperature ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Wang, Wu-yang; Cao, Da-peng; Wang, Chao; Zhang, Xiang-yu; Mi, Bao-xiu; Gao, Zhi-qiang; Liang, Zhong-cheng

    2016-07-01

    Additives and iodine (I2) are used to modify the binary room temperature ionic liquid (RTIL) electrolyte to enhance the photovoltaic performance of dye-sensitized solar cells (DSSCs). The short-circuit current density ( J SC) of 17.89 mA/cm2, open circuit voltage ( V OC) of 0.71 V and fill factor ( FF) of 0.50 are achieved in the optimal device. An average photoelectric conversion efficiency ( PCE) of 6.35% is achieved by optimization, which is over two times larger than that of the parent device before optimization (2.06%), while the maximum PCE can reach up to 6.63%.

  16. Comprehensive study of efficient dye-sensitized solar cells based on the binary ionic liquid electrolyte by modifying with additives and iodine

    NASA Astrophysics Data System (ADS)

    Mo, Ao-qiang; Cao, Da-peng; Wang, Wu-yang; Li, Xue-yan; Mi, Bao-xiu; Gao, Zhi-qiang; Liang, Zhong-cheng

    2017-07-01

    The photovoltaic performance of dye-sensitized solar cells (DSSCs) is enhanced by modifying the binary room temperature ionic liquid (RTIL) electrolyte with additives and iodine. The average photoelectric conversion efficiency ( PCE) of 6.39% is achieved. Through electrochemical impedance spectroscopy (EIS), cyclic voltammetry scans and incident photon-to-current conversion efficiency ( IPCE) data, the working principles are analyzed. The enhancement is mainly attributed to the improvement of short circuit current which is caused by the reduction of overall internal resistance of the devices. Durability tests are measured at room temperature, and the long-term stability performance can be maintained.

  17. Effect of sodium acetate additive in successive ionic layer adsorption and reaction on the performance of CdS quantum-dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, I.-Ping; Chen, Liang-Yih; Lee, Yuh-Lang

    2016-09-01

    Sodium acetate (NaAc) is utilized as an additive in cationic precursors of the successive ionic layer adsorption and reaction (SILAR) process to fabricate CdS quantum-dot (QD)-sensitized photoelectrodes. The effects of the NaAc concentration on the deposition rate and distribution of QDs in mesoporous TiO2 films, as well as on the performance of CdS-sensitized solar cells are studied. The experimental results show that the presence of NaAc can significantly accelerate the deposition of CdS, improve the QD distribution across photoelectrodes, and thereby, increase the performance of solar cells. These results are mainly attributed to the pH-elevation effect of NaAc to the cationic precursors which increases the electrostatic interaction of the TiO2 film to cadmium ions. The light-to-energy conversion efficiency of the CdS-sensitized solar cell increases with increasing concentration of the NaAc and approaches a maximum value (3.11%) at 0.05 M NaAc. Additionally, an ionic exchange is carried out on the photoelectrode to transform the deposited CdS into CdS1-xSex ternary QDs. The light-absorption range of the photoelectrode is extended and an exceptional power conversion efficiency of 4.51% is achieved due to this treatment.

  18. Ionic liquid containing hydroxamate and N-alkyl sulfamate ions

    DOEpatents

    Friesen, Cody A.; Wolfe, Derek; Johnson, Paul Bryan

    2016-03-15

    Embodiments of the invention are related to ionic liquids and more specifically to ionic liquids used in electrochemical metal-air cells in which the ionic liquid includes a cation and an anion selected from hydroxamate and/or N-alkyl sulfamate anions.

  19. Regulation of Cell Wall-Bound Invertase in Pepper Leaves by Xanthomonas campestris pv. vesicatoria Type Three Effectors

    PubMed Central

    Sonnewald, Sophia; Priller, Johannes P. R.; Schuster, Julia; Glickmann, Eric; Hajirezaei, Mohammed-Reza; Siebig, Stefan; Mudgett, Mary Beth; Sonnewald, Uwe

    2012-01-01

    Xanthomonas campestris pv. vesicatoria (Xcv) possess a type 3 secretion system (T3SS) to deliver effector proteins into its Solanaceous host plants. These proteins are involved in suppression of plant defense and in reprogramming of plant metabolism to favour bacterial propagation. There is increasing evidence that hexoses contribute to defense responses. They act as substrates for metabolic processes and as metabolic semaphores to regulate gene expression. Especially an increase in the apoplastic hexose-to-sucrose ratio has been suggested to strengthen plant defense. This shift is brought about by the activity of cell wall-bound invertase (cw-Inv). We examined the possibility that Xcv may employ type 3 effector (T3E) proteins to suppress cw-Inv activity during infection. Indeed, pepper leaves infected with a T3SS-deficient Xcv strain showed a higher level of cw-Inv mRNA and enzyme activity relative to Xcv wild type infected leaves. Higher cw-Inv activity was paralleled by an increase in hexoses and mRNA abundance for the pathogenesis-related gene PRQ. These results suggest that Xcv suppresses cw-Inv activity in a T3SS-dependent manner, most likely to prevent sugar-mediated defense signals. To identify Xcv T3Es that regulate cw-Inv activity, a screen was performed with eighteen Xcv strains, each deficient in an individual T3E. Seven Xcv T3E deletion strains caused a significant change in cw-Inv activity compared to Xcv wild type. Among them, Xcv lacking the xopB gene (Xcv ΔxopB) caused the most prominent increase in cw-Inv activity. Deletion of xopB increased the mRNA abundance of PRQ in Xcv ΔxopB-infected pepper leaves, but not of Pti5 and Acre31, two PAMP-triggered immunity markers. Inducible expression of XopB in transgenic tobacco inhibited Xcv-mediated induction of cw-Inv activity observed in wild type plants and resulted in severe developmental phenotypes. Together, these data suggest that XopB interferes with cw-Inv activity in planta to suppress sugar

  20. Regulation of cell wall-bound invertase in pepper leaves by Xanthomonas campestris pv. vesicatoria type three effectors.

    PubMed

    Sonnewald, Sophia; Priller, Johannes P R; Schuster, Julia; Glickmann, Eric; Hajirezaei, Mohammed-Reza; Siebig, Stefan; Mudgett, Mary Beth; Sonnewald, Uwe

    2012-01-01

    Xanthomonas campestris pv. vesicatoria (Xcv) possess a type 3 secretion system (T3SS) to deliver effector proteins into its Solanaceous host plants. These proteins are involved in suppression of plant defense and in reprogramming of plant metabolism to favour bacterial propagation. There is increasing evidence that hexoses contribute to defense responses. They act as substrates for metabolic processes and as metabolic semaphores to regulate gene expression. Especially an increase in the apoplastic hexose-to-sucrose ratio has been suggested to strengthen plant defense. This shift is brought about by the activity of cell wall-bound invertase (cw-Inv). We examined the possibility that Xcv may employ type 3 effector (T3E) proteins to suppress cw-Inv activity during infection. Indeed, pepper leaves infected with a T3SS-deficient Xcv strain showed a higher level of cw-Inv mRNA and enzyme activity relative to Xcv wild type infected leaves. Higher cw-Inv activity was paralleled by an increase in hexoses and mRNA abundance for the pathogenesis-related gene PRQ. These results suggest that Xcv suppresses cw-Inv activity in a T3SS-dependent manner, most likely to prevent sugar-mediated defense signals. To identify Xcv T3Es that regulate cw-Inv activity, a screen was performed with eighteen Xcv strains, each deficient in an individual T3E. Seven Xcv T3E deletion strains caused a significant change in cw-Inv activity compared to Xcv wild type. Among them, Xcv lacking the xopB gene (Xcv ΔxopB) caused the most prominent increase in cw-Inv activity. Deletion of xopB increased the mRNA abundance of PRQ in Xcv ΔxopB-infected pepper leaves, but not of Pti5 and Acre31, two PAMP-triggered immunity markers. Inducible expression of XopB in transgenic tobacco inhibited Xcv-mediated induction of cw-Inv activity observed in wild type plants and resulted in severe developmental phenotypes. Together, these data suggest that XopB interferes with cw-Inv activity in planta to suppress sugar

  1. Boosting current generation in microbial fuel cells by an order of magnitude by coating an ionic liquid polymer on carbon anodes.

    PubMed

    Yang, Lu; Deng, Wenfang; Zhang, Youming; Tan, Yueming; Ma, Ming; Xie, Qingji

    2017-05-15

    Microbial fuel cells (MFCs) have attracted great attentions due to their great application potentials, but the relatively low power densities of MFCs still hinder their widespread practical applications. Herein, we report that the current generation in MFCs can be boosted by an order of magnitude, simply by coating a hydrophilic and positively charged ionic liquid polymer (ILP) on carbon cloth (CC) or carbon felt (CF). The ILP coating not only can increase the bacterial loading capacity due to the electrostatic interactions between ILP and bacterial cells, but also can improve the mediated extracellular electron transfer between the electrode and the cytochrome proteins on the outer membrane of Shewanella putrefaciens cells. As a result, the maximum power density of a MFC equipped with the CF-ILP bioanode is as high as 4400±170mWm(-2), which is amongst the highest values reported to date. This work demonstrates a new strategy for greatly boosting the current generation in MFCs.

  2. Re-Directing CD4(+) T Cell Responses with the Flanking Residues of MHC Class II-Bound Peptides: The Core is Not Enough.

    PubMed

    Holland, Christopher J; Cole, David K; Godkin, Andrew

    2013-01-01

    Recombinant αβ T cell receptors, expressed on T cell membranes, recognize short peptides presented at the cell surface in complex with MHC molecules. There are two main subsets of αβ T cells: CD8(+) T cells that recognize mainly cytosol-derived peptides in the context of MHC class I (pMHC-I), and CD4(+) T cells that recognize peptides usually derived from exogenous proteins presented by MHC class II (pMHC-II). Unlike the more uniform peptide lengths (usually 8-13mers) bound in the MHC-I closed groove, MHC-II presented peptides are of a highly variable length. The bound peptides consist of a core bound 9mer (reflecting the binding motif for the particular MHC-II type) but with variable peptide flanking residues (PFRs) that can extend from both the N- and C-terminus of the MHC-II binding groove. Although pMHC-I and pMHC-II play a virtually identical role during T cell responses (T cell antigen presentation) and are very similar in overall conformation, there exist a number of subtle but important differences that may govern the functional dichotomy observed between CD8(+) and CD4(+) T cells. Here, we provide an overview of the impact of structural differences between pMHC-I and pMHC-II and the molecular interactions with the T cell receptor including the functional importance of MHC-II PFRs. We consider how factors such as anatomical location, inflammatory milieu, and particular types of antigen presenting cell might, in theory, contribute to the quantitative (i.e., pMHC ligand frequency) as well as qualitative (i.e., variable PFR) nature of peptide epitopes, and hence offer a means of control and influence of a CD4(+) T cell response. Lastly, we review our recent findings showing how modifications to MHC-II PFRs can modify CD4(+) T cell antigen recognition. These findings may have novel applications for the development of CD4(+) T cell peptide vaccines and diagnostics.

  3. The Synthesis and Characterization of Ionic Liquids for Alkali-Metal Batteries and a Novel Electrolyte for Non-Humidified Fuel Cells

    NASA Astrophysics Data System (ADS)

    Tucker, Telpriore G.

    This thesis focused on physicochemical and electrochemical projects directed towards two electrolyte types: 1) class of ionic liquids serving as electrolytes in the catholyte for alkali-metal ion conduction in batteries and 2) gel membrane for proton conduction in fuel cells; where overall aims were encouraged by the U.S. Department of Energy. Large-scale, sodium-ion batteries are seen as global solutions to providing undisrupted electricity from sustainable, but power-fluctuating, energy production in the near future. Foreseen ideal advantages are lower cost without sacrifice of desired high-energy densities relative to present lithium-ion and lead-acid battery systems. Na/NiCl2 (ZEBRA) and Na/S battery chemistries, suffer from high operation temperature (>300ºC) and safety concerns following major fires consequent of fuel mixing after cell-separator rupturing. Initial interest was utilizing low-melting organic ionic liquid, [EMI+][AlCl 4-], with well-known molten salt, NaAlCl4, to create a low-to-moderate operating temperature version of ZEBRA batteries; which have been subject of prior sodium battery research spanning decades. Isothermal conductivities of these electrolytes revealed a fundamental kinetic problem arisen from "alkali cation-trapping effect" yet relived by heat-ramping >140ºC. Battery testing based on [EMI+][FeCl4 -] with NaAlCl4 functioned exceptional (range 150-180ºC) at an impressive energy efficiency >96%. Newly prepared inorganic ionic liquid, [PBr4+][Al2Br7-]:NaAl2Br 7, melted at 94ºC. NaAl2Br7 exhibited super-ionic conductivity 10-1.75 Scm-1 at 62ºC ensued by solid-state rotator phase transition. Also improved thermal stability when tested to 265ºC and less expensive chemical synthesis. [PBr4 +][Al2Br7-] demonstrated remarkable, ionic decoupling in the liquid-state due to incomplete bromide-ion transfer depicted in NMR measurements. Fuel cells are electrochemical devices generating electrical energy reacting hydrogen/oxygen gases

  4. Promising Cell Configuration for Next-Generation Energy Storage: Li2S/Graphite Battery Enabled by a Solvate Ionic Liquid Electrolyte.

    PubMed

    Li, Zhe; Zhang, Shiguo; Terada, Shoshi; Ma, Xiaofeng; Ikeda, Kohei; Kamei, Yutaro; Zhang, Ce; Dokko, Kaoru; Watanabe, Masayoshi

    2016-06-29

    Lithium-ion sulfur batteries with a [graphite|solvate ionic liquid electrolyte|lithium sulfide (Li2S)] structure are developed to realize high performance batteries without the issue of lithium anode. Li2S has recently emerged as a promising cathode material, due to its high theoretical specific capacity of 1166 mAh/g and its great potential in the development of lithium-ion sulfur batteries with a lithium-free anode such as graphite. Unfortunately, the electrochemical Li(+) intercalation/deintercalation in graphite is highly electrolyte-selective: whereas the process works well in the carbonate electrolytes inherited from Li-ion batteries, it cannot take place in the ether electrolytes commonly used for Li-S batteries, because the cointercalation of the solvent destroys the crystalline structure of graphite. Thus, only very few studies have focused on graphite-based Li-S full cells. In this work, simple graphite-based Li-S full cells were fabricated employing electrolytes beyond the conventional carbonates, in combination with highly loaded Li2S/graphene composite cathodes (Li2S loading: 2.2 mg/cm(2)). In particular, solvate ionic liquids can act as a single-phase electrolyte simultaneously compatible with both the Li2S cathode and the graphite anode and can further improve the battery performance by suppressing the shuttle effect. Consequently, these lithium-ion sulfur batteries show a stable and reversible charge-discharge behavior, along with a very high Coulombic efficiency.

  5. Induction of soluble and cell wall peroxidases by aphid infestation in barley.

    PubMed

    Chaman, M E; Corcuera, L J; Zúñiga, G E; Cardemil, L; Argandoña, V H

    2001-05-01

    Peroxidase enzymes have been found in soluble, ionically bound, and covalently bound forms and have been implicated in several physiological processes in plants. This paper investigates the effect of aphid infestation on soluble and bound-cell wall peroxidase activity and bound-cell wall isoform changes of barley plants. Peroxidase activity was measured in control plants and plants infested with the aphid Schizaphis graminum (Rondani). The activity of soluble peroxidases increased with time of infestation, older plants being more affected than younger ones. The increase in bound-cell wall peroxidase activity as a function of age was higher in infested than in control plants, being higher in ionically bound than in covalently bound peroxidases. When the aphids were removed from plants, the activities of both types of peroxidases decreased to control levels. Isoelectrofocusing analyses of the ionically bound peroxidases showed changes in the isoform pattern. A new isoform was induced by infestation. The activities of all covalently bound isoforms increased after infestation. The physiological implications of these changes are discussed.

  6. Ionic liquids behave as dilute electrolyte solutions

    PubMed Central

    Gebbie, Matthew A.; Valtiner, Markus; Banquy, Xavier; Fox, Eric T.; Henderson, Wesley A.; Israelachvili, Jacob N.

    2013-01-01

    We combine direct surface force measurements with thermodynamic arguments to demonstrate that pure ionic liquids are expected to behave as dilute weak electrolyte solutions, with typical effective dissociated ion concentrations of less than 0.1% at room temperature. We performed equilibrium force–distance measurements across the common ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) using a surface forces apparatus with in situ electrochemical control and quantitatively modeled these measurements using the van der Waals and electrostatic double-layer forces of the Derjaguin–Landau–Verwey–Overbeek theory with an additive repulsive steric (entropic) ion–surface binding force. Our results indicate that ionic liquids screen charged surfaces through the formation of both bound (Stern) and diffuse electric double layers, where the diffuse double layer is comprised of effectively dissociated ionic liquid ions. Additionally, we used the energetics of thermally dissociating ions in a dielectric medium to quantitatively predict the equilibrium for the effective dissociation reaction of [C4mim][NTf2] ions, in excellent agreement with the measured Debye length. Our results clearly demonstrate that, outside of the bound double layer, most of the ions in [C4mim][NTf2] are not effectively dissociated and thus do not contribute to electrostatic screening. We also provide a general, molecular-scale framework for designing ionic liquids with significantly increased dissociated charge densities via judiciously balancing ion pair interactions with bulk dielectric properties. Our results clear up several inconsistencies that have hampered scientific progress in this important area and guide the rational design of unique, high–free-ion density ionic liquids and ionic liquid blends. PMID:23716690

  7. Ionic liquids behave as dilute electrolyte solutions.

    PubMed

    Gebbie, Matthew A; Valtiner, Markus; Banquy, Xavier; Fox, Eric T; Henderson, Wesley A; Israelachvili, Jacob N

    2013-06-11

    We combine direct surface force measurements with thermodynamic arguments to demonstrate that pure ionic liquids are expected to behave as dilute weak electrolyte solutions, with typical effective dissociated ion concentrations of less than 0.1% at room temperature. We performed equilibrium force-distance measurements across the common ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) using a surface forces apparatus with in situ electrochemical control and quantitatively modeled these measurements using the van der Waals and electrostatic double-layer forces of the Derjaguin-Landau-Verwey-Overbeek theory with an additive repulsive steric (entropic) ion-surface binding force. Our results indicate that ionic liquids screen charged surfaces through the formation of both bound (Stern) and diffuse electric double layers, where the diffuse double layer is comprised of effectively dissociated ionic liquid ions. Additionally, we used the energetics of thermally dissociating ions in a dielectric medium to quantitatively predict the equilibrium for the effective dissociation reaction of [C4mim][NTf2] ions, in excellent agreement with the measured Debye length. Our results clearly demonstrate that, outside of the bound double layer, most of the ions in [C4mim][NTf2] are not effectively dissociated and thus do not contribute to electrostatic screening. We also provide a general, molecular-scale framework for designing ionic liquids with significantly increased dissociated charge densities via judiciously balancing ion pair interactions with bulk dielectric properties. Our results clear up several inconsistencies that have hampered scientific progress in this important area and guide the rational design of unique, high-free-ion density ionic liquids and ionic liquid blends.

  8. ARTICLE Ionic Conduction and Fuel Cell Performance of Ba0.98Ce0.8Tm0.2O3-α Ceramic

    NASA Astrophysics Data System (ADS)

    Qiu, Li-gan; Wang, Mao-yuan

    2010-12-01

    The perovskite-type oxide solid solution Ba0.98Ce0.8Tm0.2O3-α was prepared by high temperature solid-state reaction and its single phase character was confirmed by X-ray diffraction. The conduction property of the sample was investigated by alternating current impedance spectroscopy and gas concentration cell methods under different gases atmospheres in the temperature range of 500-900°C. The performance of the hydrogen-air fuel cell using the sample as solid electrolyte was measured. In wet hydrogen, the sample is a pure protonic conductor with the protonic transport number of 1 in the range of 500-600 °C, a mixed conductor of proton and electron with the protonic transport number of 0.945-0.933 above 600 °C. In wet air, the sample is a mixed conductor of proton, oxide ion, and electronic hole. The protonic transport numbers are 0.010-0.021, and the oxide ionic transport numbers are 0.471-0.382. In hydrogen-air fuel cell, the sample is a mixed conductor of proton, oxide ion and electron, the ionic transport numbers are 0.942-0.885. The fuel cell using Ba0.98Ce0.8Tm0.2O3-α as solid electrolyte can work stably. At 900 °C, the maximum power output density is 110.2 mW/cm2, which is higher than that of our previous cell using BaxCe0.8RE0.2O3-α (x<=1, RE=Y, Eu, Ho) as solid electrolyte.

  9. Synthesis and Characterization of Ionically Crosslinked Elastomers

    DTIC Science & Technology

    2015-05-12

    represent an underutilized non‐ covalent ,  dynamic  bond  that is useful for the development of responsive polymers. To test this hypothesis  ionically...response of polymers crosslinked by organic ion pairs, where both the cation and anion are covalently bound to the polymer chain. Two main routes of...Box 12211 Research Triangle Park, NC 27709-2211 Elastomer, Ionomer, Polymer, Ionic Bonds REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT

  10. A hemicellulose-bound form of silicon with potential to improve the mechanical properties and regeneration of the cell wall of rice.

    PubMed

    He, Congwu; Ma, Jie; Wang, Lijun

    2015-05-01

    Silicon (Si) plays a large number of diverse roles in plants, but the structural and chemical mechanisms operating at the single-cell level remain unclear. We isolate the cell walls from suspension-cultured individual cells of rice (Oryza sativa) and fractionate them into three main fractions including cellulose (C), hemicellulose (HC) and pectin (P). We find that most of the Si is in HC as determined by inductively coupled plasma-mass spectrometry (ICP-MS), where Si may covalently crosslink the HC polysacchrides confirmed by X-ray photoelectron spectroscopy (XPS). The HC-bound form of Si could improve both the mechanical property and regeneration of the cell walls investigated by a combination of atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). This study provides further evidence that HC could be the major ligand bound to Si, which broadens our understanding of the chemical nature of 'anomalous' Si in plant cell walls. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  11. Comparison of the Antiproliferative Activity of Two Antitumour Ruthenium(III) Complexes With Their Apotransferrin and Transferrin-Bound Forms in a Human Colon Cancer Cell Line

    PubMed Central

    Keppler, B. K.; Hartmann, M.; Messori, L.; Berger, M. R.

    1996-01-01

    Two ruthenium(III) complexes, namely trans-indazolium[tetrachlorobis(indazole)- ruthenate(III)], HInd[RuInd2Cl4] and trans-imidazolium[tetrachlorobis(imidazole)- ruthenate(III)], HIm[RuIm2Cl4] exhibit high anticancer activity in an autochthonous colorectal carcinoma model in rats. Recently, it has been shown that both complexes bind specifically to human serum apotransferrin and the resulting adducts have been studied through spectroscopic and chromatographic techniques with the ultimate goal of preparing adducts with good selectivity for cancer cells due to the fact that tumour cells express high amounts of transferrin receptors on their cell surface. In order to investigate whether the cellular uptake of the complexes was mediated by apotransferrin or transferrin, we compared the antiproliferative efficacy of HInd[RuInd2Cl4] and HIm[RuIm2Cl4] with its apotransferrin- and transferrin-bound form in the human colon cancer cell line SW707 using the microculture tetrazolium test (MTT). Our results show that especially the transferrin-bound forms exhibit high antiproliferative activity, which exceeds that of the free complex, indicating that this protein can act as a carrier of the ruthenium complexes into the tumor cell. PMID:18472789

  12. Human NKT cells mediate antitumor cytotoxicity directly by recognizing target cell CD1d with bound ligand or indirectly by producing IL-2 to activate NK cells.

    PubMed

    Metelitsa, L S; Naidenko, O V; Kant, A; Wu, H W; Loza, M J; Perussia, B; Kronenberg, M; Seeger, R C

    2001-09-15

    alpha-Galactosylceramide (alphaGalCer) stimulates NKT cells and has antitumor activity in mice. Murine NKT cells may directly kill tumor cells and induce NK cell cytotoxicity, but the mechanisms are not well defined. Newly developed human CD1d/alphaGalCer tetrameric complexes were used to obtain highly purified human alphaGalCer-reactive NKT cell lines (>99%), and the mechanisms of NKT cell cytotoxicity and activation of NK cells were investigated. Human NKT cells were cytotoxic against CD1d(-) neuroblastoma cells only when they were rendered CD1d(+) by transfection and pulsed with alphaGalCer. Four other CD1d(-) tumor cell lines of diverse origin were resistant to NKT cells, whereas Jurkat and U937 leukemia cell lines, which are constitutively CD1d(+), were killed. Killing of the latter was greatly augmented in the presence of alphaGalCer. Upon human CD1d/alphaGalCer recognition, NKT cells induced potent cytotoxicity of NK cells against CD1d(-) neuroblastoma cell lines that were not killed directly by NKT cells. NK cell activation depended upon NKT cell production of IL-2, and was enhanced by secretion of IFN-gamma. These data demonstrate that cytotoxicity of human NKT cells can be CD1d and ligand dependent, and that TCR-stimulated NKT cells produce IL-2 that is required to induce NK cell cytotoxicity. Thus, NKT cells can mediate potent antitumor activity both directly by targeting CD1d and indirectly by activating NK cells.

  13. Proteins tightly bound to DNA: new data and old problems.

    PubMed

    Sjakste, N; Bagdoniene, L; Gutcaits, A; Labeikyte, D; Bielskiene, K; Trapiņa, I; Muižnieks, I; Vassetzky, Y; Sjakste, T

    2010-10-01

    Proteins tightly bound to DNA (TBP) comprise a group of proteins that remain bound to DNA after usual deproteinization procedures such as salting out and treatment with phenol or chloroform. TBP bind to DNA by covalent phosphotriester and noncovalent ionic and hydrogen bonds. Some TBP are conservative, and they are usually covalently bound to DNA. However, the TBP composition is very diverse and significantly different in different tissues and in different organisms. TBP include transcription factors, enzymes of the ubiquitin-proteasome system, phosphatases, protein kinases, serpins, and proteins of retrotransposons. Their distribution within the genome is nonrandom. However, the DNA primary structure or DNA curvatures do not define the affinity of TBP to DNA. But there are repetitive DNA sequences with which TBP interact more often. The TBP distribution within genes and chromosomes depends on a cell's physiological state, differentiation type, and stage of organism development. TBP do not interact with DNA in the sites of its association with nuclear matrix and most likely they are not components of the latter.

  14. Transfusion of human volunteers with older, stored red blood cells produces extravascular hemolysis and circulating non-transferrin-bound iron.

    PubMed

    Hod, Eldad A; Brittenham, Gary M; Billote, Genia B; Francis, Richard O; Ginzburg, Yelena Z; Hendrickson, Jeanne E; Jhang, Jeffrey; Schwartz, Joseph; Sharma, Shruti; Sheth, Sujit; Sireci, Anthony N; Stephens, Hannah L; Stotler, Brie A; Wojczyk, Boguslaw S; Zimring, James C; Spitalnik, Steven L

    2011-12-15

    Transfusions of RBCs stored for longer durations are associated with adverse effects in hospitalized patients. We prospectively studied 14 healthy human volunteers who donated standard leuko-reduced, double RBC units. One unit was autologously transfused "fresh" (3-7 days of storage), and the other "older" unit was transfused after 40 to 42 days of storage. Of the routine laboratory parameters measured at defined times surrounding transfusion, significant differences between fresh and older transfusions were only observed in iron parameters and markers of extravascular hemolysis. Compared with fresh RBCs, mean serum total bilirubin increased by 0.55 mg/dL at 4 hours after transfusion of older RBCs (P = .0003), without significant changes in haptoglobin or lactate dehydrogenase. In addition, only after the older transfusion, transferrin saturation increased progressively over 4 hours to a mean of 64%, and non-transferrin-bound iron appeared, reaching a mean of 3.2μM. The increased concentrations of non-transferrin-bound iron correlated with enhanced proliferation in vitro of a pathogenic strain of Escherichia coli (r = 0.94, P = .002). Therefore, circulating non-transferrin-bound iron derived from rapid clearance of transfused, older stored RBCs may enhance transfusion-related complications, such as infection.

  15. Transfusion of human volunteers with older, stored red blood cells produces extravascular hemolysis and circulating non–transferrin-bound iron

    PubMed Central

    Brittenham, Gary M.; Billote, Genia B.; Francis, Richard O.; Ginzburg, Yelena Z.; Hendrickson, Jeanne E.; Jhang, Jeffrey; Schwartz, Joseph; Sharma, Shruti; Sheth, Sujit; Sireci, Anthony N.; Stephens, Hannah L.; Stotler, Brie A.; Wojczyk, Boguslaw S.; Zimring, James C.; Spitalnik, Steven L.

    2011-01-01

    Transfusions of RBCs stored for longer durations are associated with adverse effects in hospitalized patients. We prospectively studied 14 healthy human volunteers who donated standard leuko-reduced, double RBC units. One unit was autologously transfused “fresh” (3-7 days of storage), and the other “older” unit was transfused after 40 to 42 days of storage. Of the routine laboratory parameters measured at defined times surrounding transfusion, significant differences between fresh and older transfusions were only observed in iron parameters and markers of extravascular hemolysis. Compared with fresh RBCs, mean serum total bilirubin increased by 0.55 mg/dL at 4 hours after transfusion of older RBCs (P = .0003), without significant changes in haptoglobin or lactate dehydrogenase. In addition, only after the older transfusion, transferrin saturation increased progressively over 4 hours to a mean of 64%, and non–transferrin-bound iron appeared, reaching a mean of 3.2μM. The increased concentrations of non–transferrin-bound iron correlated with enhanced proliferation in vitro of a pathogenic strain of Escherichia coli (r = 0.94, P = .002). Therefore, circulating non–transferrin-bound iron derived from rapid clearance of transfused, older stored RBCs may enhance transfusion-related complications, such as infection. The trial was registered with www.clinicaltrials.gov as #NCT01319552. PMID:22021369

  16. Lithium-Air and ionic Liquids

    SciTech Connect

    Kellar, Michael

    2015-09-01

    The final portion of this project was accomplished at Sandia National Labs, Livermore, with the overall goal being to optimize lithium-air cells with an ionic liquid electrolyte. Both of these are potential future routes for lithium-ion technology. Lithiumair presents the advantage of higher gravimetric energy density, and ionic liquids present the advantage of greater hydrophobicity and much lower volatility, along with a larger window of electrochemical stability. Ionic liquids however have several drawbacks for the battery industry. Currently they are not as cost effective as many organic solvents. Additionally, because of the added viscosity of ionic interactions compared to the typical dipole interactions of a solvent, the ionic conductivity is lower than for common organic solvents.

  17. The Miniature-1 (Mn1) gene product, cell wall invertase-2 (INCW2), is associated with wall-in-growths (WIGs) is basal endosperm transfer cells (BETCs) in developing seeds of maize

    USDA-ARS?s Scientific Manuscript database

    Cell wall invertases (CWI) are ionically bound to the cell wall in plant cells. A major CWI, INCW2, encoded by the Mn1 gene, provides the gateway to sucrose metabolism in developing seeds as it is entirely and exclusively localized to the BETCs that juxtapose the pedicel. The loss of INCW2 protein ...

  18. Enhanced ionic conductivity in Gd-doped ceria and (Li/Na)2SO4 composite electrolytes for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Yao, Chuangang; Meng, Junling; Liu, Xiaojuan; Zhang, Xiong; Liu, Xiliang; Meng, Fanzhi; Wu, Xiaojie; Meng, Jian

    2015-11-01

    A series of novel composite electrolytes based on 20 mol% Gd doped CeO2 with varying amounts of (Li/Na)2SO4 have been synthesized. X-ray diffraction, thermogravimetry and differential scanning calorimetry, scanning electron microscope and transmission electron microscope were applied to characterize the phase components and microstructures of the composite electrolytes. Their ionic conductivities were determined by AC impedance spectroscopy. It has been found that the optimum sintering temperature and sulphate content for the composite electrolyte is 870 °C and 20 wt% (Li/Na)2SO4, respectively. Above 550 °C, a sharp increase in conductivity occurred, which can be interpreted as superionic phase transitions in the interface phases between GDC and sulphates. Both the high ionic conductivities above the transition temperature, 0.191, 0.298 and 0.372 S cm-1 at 550, 650 and 750 °C respectively, and low activation energy (0.303 eV) highlight composite GDC-20 wt% (Li/Na)2SO4 a promising electrolyte candidate for application in intermediate temperature solid oxide fuel cells.

  19. Lithium-modulated conduction band edge shifts and charge-transfer dynamics in dye-sensitized solar cells based on a dicyanamide ionic liquid.

    PubMed

    Bai, Yu; Zhang, Jing; Wang, Yinghui; Zhang, Min; Wang, Peng

    2011-04-19

    Lithium ions are known for their potent function in modulating the energy alignment at the oxide semiconductor/dye/electrolyte interface in dye-sensitized solar cells (DSCs), offering the opportunity to control the associated multichannel charge-transfer dynamics. Herein, by optimizing the lithium iodide content in 1-ethyl-3-methylimidazolium dicyanamide-based ionic liquid electrolytes, we present a solvent-free DSC displaying an impressive 8.4% efficiency at 100 mW cm(-2) AM1.5G conditions. We further scrutinize the origins of evident impacts of lithium ions upon current density-voltage characteristics as well as photocurrent action spectra of DSCs based thereon. It is found that, along with a gradual increase of the lithium content in ionic liquid electrolytes, a consecutive diminishment of the open-circuit photovoltage arises, primarily owing to a noticeable downward movement of the titania conduction band edge. The conduction band edge displacement away from vacuum also assists the formation of a more favorable energy offset at the titania/dye interface, and thereby leads to a faster electron injection rate and a higher exciton dissociation yield as implied by transient emission measurements. We also notice that the adverse influence of the titania conduction band edge downward shift arising from lithium addition upon photovoltage is partly compensated by a concomitant suppression of the triiodide involving interfacial charge recombination. © 2011 American Chemical Society

  20. The interaction between ionic liquids modified magnetic nanoparticles and bovine serum albumin and the cytotoxicity to HepG-2 cells.

    PubMed

    Xue, Juan-Juan; Chen, Qiu-Yun

    2014-01-01

    The interaction between ionic liquids modified magnetic Fe3O4 (Fe2) and bovine serum albumin (BSA) is reported and is compared with NH2 functionalized magnetic nanoparticles Fe3O4 (Fe1) based on the UV-visible spectrum, steady-state fluorescence measurements, synchronous fluorescence and DSC methods. The results indicate a static quenching mechanism operating in both nanoparticles. The binding constant of the Fe2-BSA complex calculated from fluorescence data shows that BSA has a low binding affinity for Fe2 than Fe1. DSC data reveal that the thermal stability process of BSA in the Fe2-BSA complex is semi-reversible. This demonstrates that the ionic liquid modified magnetic nanoparticles (Fe2) enhance the thermostability of BSA in the range of 20-40°C, and protein attached Fe2 has higher thermal stability than free BSA. Moreover, the in vitro assay results show that Fe2 shows low cytotoxicity to HepG-2 cells.

  1. Proton conducting sulfonated poly (imide-benzimidazole) with tunable density of covalent/ionic cross-linking for fuel cell membranes

    NASA Astrophysics Data System (ADS)

    Yue, Zhouying; Cai, Yang-Ben; Xu, Shiai

    2015-07-01

    Ionic cross-linked sulfonated polyimides containing bis-benzimidazole rings have been prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 6,6‧-bis[2-(4-aminophenyl)benzimidazole] (BAPBI) and 3,3‧-bis(4-sulfophenoxy)- benzidine (BSPOB). A new cross-linker, 4,4‧-bibromomethenyl diphenyl ether, is used to induce covalent cross-linking between halogen and imidazole groups in SPIBI chains via a facile thermally activated reaction. The resulted covalent and ionic cross-linked membranes show an improved resistance to hydrolytic attack in deionized water at 80 °C (more than two months) and free radical attack in Fenton's solution (more than 690 min) as compared to non-cross-linked SPIBIs (less than two days and 270 min, respectively). Cross-linking also results in a reduction in proton conductivity due to the blockage of a hydrophilic channel. However, all the prepared CBr-ySPIBI-x membranes show a proton conductivity higher than 10-2 S cm-1 under hydrous condition. This could be attributed to the fact that more cross-linking sites are contained in each repeating unit, which ensures enough cross-linking degree at high sulfonation level. All these results suggest that CBr-ySPIBI-x membranes have a great potential for applications in the proton exchange membrane fuel cells.

  2. Effect of the interfacial tension and ionic strength on the thermodynamic barrier associated to the benzocaine insertion into a cell membrane.

    PubMed

    López Cascales, J J; Oliveira Costa, S D

    2013-02-01

    The insertion of local anaesthetics into a cell membrane is a key aspect for explaining their activity at a molecular level. It has been described how the potency and response time of local anaesthetics is improved (for clinical applications) when they are dissolved in a solution of sodium bicarbonate. With the aim of gaining insight into the physico-chemical principles that govern the action mechanism of these drugs at a molecular level, simulations of benzocaine in binary lipid bilayers formed by DPPC/DPPS were carried out for different ionic strengths of the aqueous solution. From these molecular dynamic simulations, we observed how the thermodynamic barrier associated with benzocaine insertion into the lipid bilayers diminished exponentially as the fraction of DPPS in the bilayer increased, especially when the ionic strength of the aqueous solution increased. In line with these results, we also observed how this thermodynamic barrier diminished exponentially with the phospholipid/water interfacial tension. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Investigation of ionic conductivity and long-term stability of a LiI and KI coupled diphenylamine quasi-solid-state dye-sensitized solar cell.

    PubMed

    Agarwala, S; Peh, C K N; Ho, G W

    2011-07-01

    In this work, enhancement of ionic conductivity and long-term stability through the addition of diphenylamine (DPA) in poly(ethylene oxide) (PEO) is demonstrated. Potassium iodide (KI) is adopted as the crystal growth inhibitor, and DPA is used as a charge transport enhancer in the electrolyte. The modified electrolyte is used with titanium dioxide (TiO2) nanoparticles, which is systematically tuned to obtain high surface area. The dye-sensitized solar cell (DSSC) showed a photocurrent of 14 mAcm2 with a total conversion efficiency of 5.8% under one sun irradiation. DPA enhances the interaction of the TiO2 nanoparticle film and the I-/I3- electrolyte leading to high ionic conductivity (3.5 × 10-3 Scm-1), without compromising on the electrochemical and mechanical stability. Electrochemical impedance spectroscopy (EIS) studies show that electron transport and electron lifetime are enhanced in the DPA added electrolyte due to reduced sublimation of iodine. The most promising feature of the electrolyte is increased device stability with 89% of the overall efficiency preserved even after 40 days.

  4. Structural elucidation of Eucalyptus lignin and its dynamic changes in the cell walls during an integrated process of ionic liquids and successive alkali treatments.

    PubMed

    Li, Han-Yin; Wang, Chen-Zhou; Chen, Xue; Cao, Xue-Fei; Sun, Shao-Ni; Sun, Run-Cang

    2016-12-01

    An integrated process based on ionic liquids ([Bmim]Cl and [Bmim]OAc) pretreatment and successive alkali post-treatments (0.5, 2.0, and 4.0% NaOH at 90°C for 2h) was performed to isolate lignins from Eucalyptus. The structural features and spatial distribution of lignin in the Eucalyptus cell wall were investigated thoroughly. Results revealed that the ionic liquids pretreatment promoted the isolation of alkaline lignin from the pretreated samples without obvious structural changes. Additionally, the integrated process resulted in syringyl-rich lignin macromolecules with more β-O-4' linkages and less phenolic hydroxyl groups. Confocal Raman microscopy analysis showed that the dissolution behavior of lignin was varied in the morphologically distinct regions during the successive alkali treatments, and lignin dissolved was mainly stemmed from the secondary wall regions. These results provided some useful information for understanding the mechanisms of delignification during the integrated process and enhancing the potential utilizations of lignin in future biorefineries.

  5. Fenofibrate, a PPARα agonist, protect proximal tubular cells from albumin-bound fatty acids induced apoptosis via the activation of NF-kB

    PubMed Central

    Zuo, Nan; Zheng, Xiaoyu; Liu, Hanzhe; Ma, Xiaoli

    2015-01-01

    Albumin-bound fatty acids is the main cause of renal damage, PPARα is responsible in the metabolism of fatty acids. Previous study found that PPARα played a protective role in fatty acids overload associated tubular injury. The aim of the present study is to investigate whether fenofibrate, a PPARα ligands, could contribute to the renoprotective action in fatty acids overload proximal tubule epithelial cells. We observed in HK-2 cells that fenofibrate significantly inhibited fatty acids bound albumin (FA-BSA) induced up-regulation of MCP-1 and IL-8. Treatment with fenofibrate attenuated renal oxidative stress induced by FA-BSA as evidenced by decreased MDA level, increased SOD activity and catalase, GPx-1 expression. FA-BSA induced apoptosis of HK-2 cells were also obviously prevented by fenofibrate. Furthermore, fenofibrate significantly increased the expression of PPARα mRNA and protein in FA-BSA treated cells. Finally, the activation of NF-kB induced by FA-BSA was markedly suppressed by fenofibrate. Taken together, our study describes a renoprotective role of fenofibrate in fatty acids associated tubular toxicity, and the transcriptional activation of PPARα and suppression of NF-kB were at least partially involved. PMID:26617775

  6. Fenofibrate, a PPARα agonist, protect proximal tubular cells from albumin-bound fatty acids induced apoptosis via the activation of NF-kB.

    PubMed

    Zuo, Nan; Zheng, Xiaoyu; Liu, Hanzhe; Ma, Xiaoli

    2015-01-01

    Albumin-bound fatty acids is the main cause of renal damage, PPARα is responsible in the metabolism of fatty acids. Previous study found that PPARα played a protective role in fatty acids overload associated tubular injury. The aim of the present study is to investigate whether fenofibrate, a PPARα ligands, could contribute to the renoprotective action in fatty acids overload proximal tubule epithelial cells. We observed in HK-2 cells that fenofibrate significantly inhibited fatty acids bound albumin (FA-BSA) induced up-regulation of MCP-1 and IL-8. Treatment with fenofibrate attenuated renal oxidative stress induced by FA-BSA as evidenced by decreased MDA level, increased SOD activity and catalase, GPx-1 expression. FA-BSA induced apoptosis of HK-2 cells were also obviously prevented by fenofibrate. Furthermore, fenofibrate significantly increased the expression of PPARα mRNA and protein in FA-BSA treated cells. Finally, the activation of NF-kB induced by FA-BSA was markedly suppressed by fenofibrate. Taken together, our study describes a renoprotective role of fenofibrate in fatty acids associated tubular toxicity, and the transcriptional activation of PPARα and suppression of NF-kB were at least partially involved.

  7. Surfactant Protein–C Chromatin-Bound Green Fluorescence Protein Reporter Mice Reveal Heterogeneity of Surfactant Protein C–Expressing Lung Cells

    PubMed Central

    Lee, Joo-Hyeon; Kim, Jonghwan; Gludish, David; Roach, Rebecca R.; Saunders, Arven H.; Barrios, Juliana; Woo, Andrew Jonghan; Chen, Huaiyong; Conner, David A.; Fujiwara, Yuko; Stripp, Barry R.

    2013-01-01

    The regeneration of alveolar epithelial cells is a critical aspect of alveolar reorganization after lung injury. Although alveolar Type II (AT2) cells have been described as progenitor cells for alveolar epithelia, more remains to be understood about how their progenitor cell properties are regulated. A nuclear, chromatin-bound green fluorescence protein reporter (H2B-GFP) was driven from the murine surfactant protein–C (SPC) promoter to generate SPC H2B-GFP transgenic mice. The SPC H2B-GFP allele allowed the FACS-based enrichment and gene expression profiling of AT2 cells. Approximately 97% of AT2 cells were GFP-labeled on Postnatal Day 1, and the percentage of GFP-labeled AT2 cells decreased to approximately 63% at Postnatal Week 8. Isolated young adult SPC H2B-GFP+ cells displayed proliferation, differentiation, and self-renewal capacity in the presence of lung fibroblasts in a Matrigel-based three-dimensional culture system. Heterogeneity within the GFP+ population was revealed, because cells with distinct alveolar and bronchiolar gene expression arose in three-dimensional cultures. CD74, a surface marker highly enriched on GFP+ cells, was identified as a positive selection marker, providing 3-fold enrichment for AT2 cells. In vivo, GFP expression was induced within other epithelial cell types during maturation of the distal lung. The utility of the SPC H2B-GFP murine model for the identification of AT2 cells was greatest in early postnatal lungs and more limited with age, when some discordance between SPC and GFP expression was observed. In adult mice, this allele may allow for the enrichment and future characterization of other SPC-expressing alveolar and bronchiolar cells, including putative stem/progenitor cell populations. PMID:23204392

  8. Surfactant protein-C chromatin-bound green fluorescence protein reporter mice reveal heterogeneity of surfactant protein C-expressing lung cells.

    PubMed

    Lee, Joo-Hyeon; Kim, Jonghwan; Gludish, David; Roach, Rebecca R; Saunders, Arven H; Barrios, Juliana; Woo, Andrew Jonghan; Chen, Huaiyong; Conner, David A; Fujiwara, Yuko; Stripp, Barry R; Kim, Carla F

    2013-03-01

    The regeneration of alveolar epithelial cells is a critical aspect of alveolar reorganization after lung injury. Although alveolar Type II (AT2) cells have been described as progenitor cells for alveolar epithelia, more remains to be understood about how their progenitor cell properties are regulated. A nuclear, chromatin-bound green fluorescence protein reporter (H2B-GFP) was driven from the murine surfactant protein-C (SPC) promoter to generate SPC H2B-GFP transgenic mice. The SPC H2B-GFP allele allowed the FACS-based enrichment and gene expression profiling of AT2 cells. Approximately 97% of AT2 cells were GFP-labeled on Postnatal Day 1, and the percentage of GFP-labeled AT2 cells decreased to approximately 63% at Postnatal Week 8. Isolated young adult SPC H2B-GFP(+) cells displayed proliferation, differentiation, and self-renewal capacity in the presence of lung fibroblasts in a Matrigel-based three-dimensional culture system. Heterogeneity within the GFP(+) population was revealed, because cells with distinct alveolar and bronchiolar gene expression arose in three-dimensional cultures. CD74, a surface marker highly enriched on GFP(+) cells, was identified as a positive selection marker, providing 3-fold enrichment for AT2 cells. In vivo, GFP expression was induced within other epithelial cell types during maturation of the distal lung. The utility of the SPC H2B-GFP murine model for the identification of AT2 cells was greatest in early postnatal lungs and more limited with age, when some discordance between SPC and GFP expression was observed. In adult mice, this allele may allow for the enrichment and future characterization of other SPC-expressing alveolar and bronchiolar cells, including putative stem/progenitor cell populations.

  9. Method and apparatus using an active ionic liquid for algae biofuel harvest and extraction

    SciTech Connect

    Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

    2012-11-06

    The invention relates to use of an active ionic liquid to dissolve algae cell walls. The ionic liquid is used to, in an energy efficient manner, dissolve and/or lyse an algae cell walls, which releases algae constituents used in the creation of energy, fuel, and/or cosmetic components. The ionic liquids include ionic salts having multiple charge centers, low, very low, and ultra low melting point ionic liquids, and combinations of ionic liquids. An algae treatment system is described, which processes wet algae in a lysing reactor, separates out algae constituent products, and optionally recovers the ionic liquid in an energy efficient manner.

  10. Prophylactic and therapeutic vaccination with carrier-bound Bet v 1 peptides lacking allergen-specific T cell epitopes reduces Bet v 1-specific T cell responses via blocking antibodies in a murine model for birch pollen allergy

    PubMed Central

    Linhart, B; Narayanan, M; Focke-Tejkl, M; Wrba, F; Vrtala, S; Valenta, R

    2014-01-01

    Background Vaccines consisting of allergen-derived peptides lacking IgE reactivity and allergen-specific T cell epitopes bound to allergen-unrelated carrier molecules have been suggested as candidates for allergen-specific immunotherapy. Objective To study whether prophylactic and therapeutic vaccination with carrier-bound peptides from the major birch pollen allergen Bet v 1 lacking allergen-specific T cell epitopes has influence on Bet v 1-specific T cell responses. Methods Three Bet v 1-derived peptides, devoid of Bet v 1-specific T cell epitopes, were coupled to KLH and adsorbed to aluminium hydroxide to obtain a Bet v 1-specific allergy vaccine. Groups of BALB/c mice were immunized with the peptide vaccine before or after sensitization to Bet v 1. Bet v 1- and peptide-specific antibody responses were analysed by ELISA. T cell and cytokine responses to Bet v 1, KLH, and the peptides were studied in proliferation assays. The effects of peptide-specific and allergen-specific antibodies on T cell responses and allergic lung inflammation were studied using specific antibodies. Results Prophylactic and therapeutic vaccination with carrier-bound Bet v 1 peptides induced a Bet v 1-specific IgG antibody response without priming/boosting of Bet v 1-specific T cells. Prophylactic and therapeutic vaccination of mice with the peptide vaccine induced Bet v 1-specific antibodies which suppressed Bet v 1-specific T cell responses and allergic lung inflammation. Conclusion and Clinical Relevance Vaccination with carrier-bound allergen-derived peptides lacking allergen-specific T cell epitopes induces allergen-specific IgG antibodies which suppress allergen-specific T cell responses and allergic lung inflammation. PMID:24447086

  11. IMIDAZOLE-BASED IONIC LIQUIDS FOR USE IN POLYMER ELECTROLYTE MEMBRANE FUEL CELLS: EFFECT OF ELECTRON-WITHDRAWING AND ELECTRON-DONATING SUBSTITUENTS

    SciTech Connect

    Chang, E.; Fu, Y.; Kerr, J.

    2009-01-01

    Current polymer electrolyte membrane fuel cells (PEMFCs) require humidifi cation for acceptable proton conductivity. Development of a novel polymer that is conductive without a water-based proton carrier is desirable for use in automobiles. Imidazole (Im) is a possible replacement for water as a proton solvent; Im can be tethered to the polymer structure by means of covalent bonds, thereby providing a solid state proton conducting membrane where the solvating groups do not leach out of the fuel cell. These covalent bonds can alter the electron availability of the Im molecule. This study investigates the effects of electron-withdrawing and electron-donating substituents on the conductivity of Im complexed with methanesulfonic acid (MSA) in the form of ionic liquids. Due to the changes in the electronegativity of nitrogen, it is expected that 2-phenylimidazole (2-PhIm, electron-withdrawing) will exhibit increased conductivity compared to Im, while 2-methylimidazole (2-MeIm, electron-donating) will exhibit decreased conductivity. Three sets of ionic liquids were prepared at defi ned molar ratios: Im-MSA, 2-PhIm-MSA, and 2-MeIm- MSA. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and 1H-NMR were used to characterize each complex. Impedance analysis was used to determine the conductivity of each complex. Both the 2-PhIm-MSA and 2-MeIm-MSA ionic liquids were found to be less conductive than the Im-MSA complex at base-rich compositions, but more conductive at acid-rich compositions. 1H-NMR data shows a downfi eld shift of the proton on nitrogen in 2-PhIm compared to Im, suggesting that other factors may diminish the electronic effects of the electron withdrawing group at base-rich compositions. Further studies examining these effects may well result in increased conductivity for Im-based complexes. Understanding the conductive properties of Im-derivatives due to electronic effects will help facilitate the development of a new electrolyte

  12. Lipid extraction from microalgae using a single ionic liquid

    DOEpatents

    Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

    2013-05-28

    A one-step process for the lysis of microalgae cell walls and separation of the cellular lipids for use in biofuel production by utilizing a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium. The hydrophilic ionic liquid both lyses the microalgae cell walls and forms two immiscible layers, one of which consists of the lipid contents of the lysed cells. After mixture of the hydrophilic ionic liquid with a suspension of microalgae cells, gravity causes a hydrophobic lipid phase to move to a top phase where it is removed from the mixture and purified. The hydrophilic ionic liquid is recycled to lyse new microalgae suspensions.

  13. Whole-cell recording from honeybee olfactory receptor neurons: ionic currents, membrane excitability and odourant response in developing workerbee and drone.

    PubMed

    Laurent, Stéphanie; Masson, Claudine; Jakob, Ingrid

    2002-04-01

    Whole-cell recording techniques were used to characterize ionic membrane currents and odourant responses in honeybee olfactory receptor neurons (ORNs) in primary cell culture. ORNs of workerbee (female) and drone (male) were isolated at an early stage of development before sensory axons connect to their target in the antennal lobe. The results collectively indicate that honeybee ORNs have electrical properties similar, but not necessarily identical to, those currently envisaged for ORNs of other species. Under voltage clamp at least four ionic currents could be distinguished. Inward currents were made of a fast transient, tetrodotoxin-sensitive sodium current. In some ORNs a cadmium-sensitive calcium current was detected. ORNs showed heterogeneity in their outward currents: either outward currents were made of a delayed rectifier type potassium current, which was partially blocked by tetraethyl ammonium or quinidine, or were composed of a delayed rectifier type and a transient calcium-dependent potassium current, which was cadmium-sensitive and abolished by removal of external calcium. The proportion of each of the two outward currents, however, was different within the ORNs of the two sexes suggesting a gender-specific functional heterogeneity. ORNs showed heterogeneity in action potential firing properties: depolarizing current steps elicited either one action potential or, as in most of the cells, it led to repetitive spiking. Action potentials were tetrodotoxin-sensitive suggesting they are carried by sodium. Odourant stimulation with different mixtures and pure substances evoked depolarizing receptor potentials with superimposed action potentials when spike threshold was reached. In summary, honeybee ORNs are remarkably mature at early stages in their development.

  14. Photo-induced electron transfer in intact cells of Rubrivivax gelatinosus mutants deleted in the RC-bound tetraheme cytochrome: insight into evolution of photosynthetic electron transport.

    PubMed

    Verméglio, André; Nagashima, Sakiko; Alric, Jean; Arnoux, Pascal; Nagashima, Kenji V P

    2012-05-01

    Deletion of two of the major electron carriers, the reaction center-bound tetrahemic cytochrome and the HiPIP, involved in the light-induced cyclic electron transfer pathway of the purple photosynthetic bacterium, Rubrivivax gelatinosus, significantly impairs its anaerobic photosynthetic growth. Analysis on the light-induced absorption changes of the intact cells of the mutants shows, however, a relatively efficient photo-induced cyclic electron transfer. For the single mutant lacking the reaction center-bound cytochrome, we present evidence that the electron carrier connecting the reaction center and the cytochrome bc(1) complex is the High Potential Iron-sulfur Protein. In the double mutant lacking both the reaction center-bound cytochrome and the High Potential Iron-sulfur Protein, this connection is achieved by the high potential cytochrome c(8). Under anaerobic conditions, the halftime of re-reduction of the photo-oxidized primary donor by these electron donors is 3 to 4 times faster than the back reaction between P(+) and the reduced primary quinone acceptor. This explains the photosynthetic growth of these two mutants. The results are discussed in terms of evolution of the type II RCs and their secondary electron donors. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. The soluble form of the membrane-bound transferrin homologue, melanotransferrin, inefficiently donates iron to cells via nonspecific internalization and degradation of the protein.

    PubMed

    Food, Michael R; Sekyere, Eric O; Richardson, Des R

    2002-09-01

    Melanotransferrin (MTf) is a membrane-bound transferrin (Tf) homologue found particularly in melanoma cells. Apart from membrane-bound MTf, a soluble form of the molecule (sMTf) has been identified in vitro[Food, M.R., Rothenberger, S., Gabathuler, R., Haidl, I.D., Reid, G. & Jefferies, W.A. (1994) J. Biol. Chem.269, 3034-3040] and in vivo in Alzheimer's disease. However, nothing is known about the function of sMTf or its role in Fe uptake. In this study, sMTf labelled with 59Fe and 125I was used to examine its ability to donate 59Fe to SK-Mel-28 melanoma cells and other cell types. sMTf donated 59Fe to cells at 14% of the rate of Tf. Analysis of sMTf binding showed that unlike Tf, sMTf did not bind to a saturable Tf-binding site. Studies with Chinese hamster ovary cells with and without specific Tf receptors showed that unlike Tf, sMTf did not donate its 59Fe via these pathways. This was confirmed by experiments using lysosomotropic agents that markedly reduced 59Fe uptake from Tf, but had far less effect on 59Fe uptake from sMTf. In addition, an excess of 56Fe-labelled Tf or sMTf had no effect on 125I-labelled sMTf uptake, suggesting a nonspecific interaction of sMTf with cells. Protein-free 125I determinations demonstrated that in contrast with Tf, sMTf was markedly degraded. We suggest that unlike the binding of Tf to specific receptors, sMTf was donating Fe to cells via an inefficient mechanism involving nonspecific internalization and subsequent degradation.

  16. Enhancement of cell growth and glycolic acid production by overexpression of membrane-bound alcohol dehydrogenase in Gluconobacter oxydans DSM 2003.

    PubMed

    Zhang, Huan; Shi, Lulu; Mao, Xinlei; Lin, Jinping; Wei, Dongzhi

    2016-11-10

    Membrane-bound alcohol dehydrogenase (mADH) was overexpressed in Gluconobacter oxydans DSM 2003, and the effects on cell growth and glycolic acid production were investigated. The transcription levels of two terminal ubiquinol oxidases (bo3 and bd) in the respiratory chain of the engineered strain G. oxydans-adhABS were up-regulated by 13.4- and 3.8-fold, respectively, which effectively enhanced the oxygen uptake rate, resulting in higher resistance to acid. The cell biomass of G. oxydans-adhABS could increase by 26%-33% when cultivated in a 7L bioreactor. The activities of other major membrane-bound dehydrogenases were also increased to some extent, particularly membrane-bound aldehyde dehydrogenase (mALDH), which is involved in the catalytic oxidation of aldehydes to the corresponding acids and was 1.26-fold higher. Relying on the advantages of the above, G. oxydans-adhABS could produce 73.3gl(-1) glycolic acid after 45h of bioconversion with resting cells, with a molar yield 93.5% and a space-time yield of 1.63gl(-1)h(-1). Glycolic acid production could be further improved by fed-batch fermentation. After 45h of culture, 113.8gl(-1) glycolic acid was accumulated, with a molar yield of 92.9% and a space-time yield of 2.53gl(-1)h(-1), which is the highest reported glycolic acid yield to date. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. QTLs for cell wall-bound phenolics in relation to the photosynthetic apparatus activity and leaf water status under drought stress at different growth stages of triticale.

    PubMed

    Hura, Tomasz; Tyrka, Mirosław; Hura, Katarzyna; Ostrowska, Agnieszka; Dziurka, Kinga

    2017-04-01

    The present study aimed at identifying the regions of triticale genome responsible for cell wall saturation with phenolic compounds under drought stress during vegetative and generative growth. Moreover, the loci determining the activity of the photosynthetic apparatus, leaf water content (LWC) and osmotic potential (Ψ o) were identified, as leaf hydration and functioning of the photosynthetic apparatus under drought are associated with the content of cell wall-bound phenolics (CWPh). Compared with LWC and Ψ o, CWPh fluctuations were more strongly associated with changes in chlorophyll fluorescence. At the vegetative stage, CWPh fluctuations were due to the activity of three loci, of which only QCWPh.4B was also related to changes in F v/F m and ABS/CSm. In the other QTLs (QCWPh.6R.2 and QCWPh.6R.3), the genes of these loci determined also the changes in majority of chlorophyll fluorescence parameters. At the generative stage, the changes in CWPh in loci QCWPh.4B, QCWPh.3R and QCWPh.6R.1 corresponded to those in DIo/CSm. The locus QCWPh.6R.3, active at V stage, controlled majority of chlorophyll fluorescence parameters. This is the first study on mapping quantitative traits in triticale plants exposed to drought at different stages of development, and the first to present the loci for cell wall-bound phenolics.

  18. Inhibition of MAP kinase promotes the recruitment of corepressor SMRT by tamoxifen-bound estrogen receptor alpha and potentiates tamoxifen action in MCF-7 cells

    SciTech Connect

    Hong, Wei; Chen, Linfeng; Li, Juan; Yao, Zhi

    2010-05-28

    Estrogen receptor alpha (ER{alpha}), a ligand controlled transcription factor, plays an important role in breast cancer growth and endocrine therapy. Tamoxifen (TAM) antagonizes ER{alpha} activity and has been applied in breast cancer treatment. TAM-bound ER{alpha} associates with nuclear receptor-corepressors. Mitogen-activated protein kinase (MAPK) has been elucidated to result in cross-talk between growth factor and ER{alpha} mediated signaling. We show that activated MAPK represses interaction of TAM-bound ER{alpha} with silencing mediator for retinoid and thyroid hormone receptors (SMRT) and inhibits the recruitment of SMRT by ER{alpha} to certain estrogen target genes. Blockade of MAPK signaling cascade with MEK inhibitor U0126 promotes the interaction and subsequently inhibits ER{alpha} activity via enhanced recruitment of SMRT, leading to reduced expression of ER{alpha} target genes. The growth rate of MCF-7 cells was decelerated when treated with both TAM and U0126. Moreover, the growth of MCF-7 cells stably expressing SMRT showed a robust repression in the presence of TAM and U0126. These results suggest that activated MAPK signaling cascade attenuates antagonist-induced recruitment of SMRT to ER{alpha}, suggesting corepressor mediates inhibition of ER{alpha} transactivation and breast cancer cell growth by antagonist. Taken together, our finding indicates combination of antagonist and MAPK inhibitor could be a helpful approach for breast cancer therapy.

  19. Efficient CdSe quantum dot-sensitized solar cells prepared by an improved successive ionic layer adsorption and reaction process.

    PubMed

    Lee, Hyojoong; Wang, Mingkui; Chen, Peter; Gamelin, Daniel R; Zakeeruddin, Shaik M; Grätzel, Michael; Nazeeruddin, Md K

    2009-12-01

    In pursuit of efficient quantum dot (QD)-sensitized solar cells based on mesoporous TiO(2) photoanodes, a new procedure for preparing selenide (Se(2-)) was developed and used for depositing CdSe QDs in situ over TiO(2) mesopores by the successive ionic layer adsorption and reaction (SILAR) process in ethanol. The sizes and density of CdSe QDs over TiO(2) were controlled by the number of SILAR cycles applied. After some optimization of these QD-sensitized TiO(2) films in regenerative photoelectrochemical cells using a cobalt redox couple [Co(o-phen)(3)(2+/3+)], including addition of a final layer of CdTe, over 4% overall efficiencies were achieved at 100 W/m(2) with about 50% IPCE at its maximum. Light-harvesting properties and transient voltage decay/impedance measurements confirmed that CdTe-terminated CdSe QD cells gave better charge-collection efficiencies and kinetic parameters than corresponding CdSe QD cells. In a preliminary study, a CdSe(Te) QD-sensitized TiO(2) film was combined with an organic hole conductor, spiro-OMeTAD, and shown to exhibit a promising efficiency of 1.6% at 100 W/m(2) in inorganic/organic hybrid all-solid-state cells.

  20. Birch's law for high-pressure metals and ionic solids: Sound velocity data comparison between shock wave experiments and recent diamond anvil cell experiments

    NASA Astrophysics Data System (ADS)

    Boness, David A.; Ware, Lucas

    2017-01-01

    Sound velocity-density systematics has long been a fruitful way to take shock wave measurements on elements, alloys, oxides, rocks, and other materials, and allow reasonable extrapolation to densities found deep in the Earth. Recent detection of super-Earths has expanded interest in terrestrial planetary interiors to an even greater range of materials and pressures. Recent published diamond anvil cell (DAC) experimental measurements of sound velocities in iron and iron alloys, relevant to planetary cores, are inconsistent with each other with regard to the validity of Birch's Law, a linear relation between sound velocity and density. We examine the range of validity of Birch's Law for several shocked metallic elements, including iron, and shocked ionic solids and make comparisons to the recent DAC data.

  1. Molecular modeling of a T-cell receptor bound to a major histocompatibility complex molecule: implications for T-cell recognition.

    PubMed

    Almagro, J C; Vargas-Madrazo, E; Lara-Ochoa, F; Horjales, E

    1995-09-01

    The main functions of the T-cell receptor (TCR) involve its specific interaction with short and linear antigenic peptides bound to the major histocompatibility complex (MHC) molecules. In the absence of a 3D structure for TCR and for the TCR/peptide/MHC complex, several attempts to characterize the structural components of the TCR/peptide/MHC interaction have been made. However, this subject is still troublesome. In this paper a computer-based 3D model for a TCR/peptide/MHC complex (5C.C7/moth cytochrome c [MCC] peptide 93-103/I-Ek) was obtained. The complex surface shows a high complementarity between the 5C.C7 structure and the peptide/I-Ek molecule. The mapping of residues involved in the TCR/peptide/MHC interaction shows close agreement with mutational experiments (Jorgensen JL, Reay PA, Ehrich EW, Davis MM, 1992b, Annu Rev Immunol 10:835-873). Moreover, the results are consistent with a recent variability analysis of TCR sequences using three variability indexes (Almagro JC, Zenteno-Cuevas R, Vargas-Madrazo E, Lara-Ochoa F, 1995b, Int J Pept Protein Res 45:180-186). Accordingly, the 3D model of the 5C.C7/MCC peptide 93-103/I-Ek complex provides a framework to generate testable hypotheses about TCR recognition. Thus, starting from this model, the role played by each loop that forms the peptide/MHC binding site of the TCR is discussed.

  2. Carbon monoxide-bound red blood cells protect red blood cell transfusion-induced hepatic cytochrome P450 impairment in hemorrhagic-shock rats.

    PubMed

    Ogaki, Shigeru; Taguchi, Kazuaki; Watanabe, Hiroshi; Otagiri, Masaki; Maruyama, Toru

    2013-01-01

    Red blood cell (RBC) transfusions for massive hemorrhage induce systemic ischemic-reperfusion and influence the disposition and pharmacological activity of drugs as a result of a reduction in the level of expression and activity of cytochrome P450s (P450). It was reported that, when organ-preserving solutions are exposed to carbon monoxide (CO), the treatment was effective in suppressing the postreperfusion reduction in renal P450 levels in cases of kidney transplantation. Therefore, we hypothesized that transfusions with RBC that contain bound CO (CO-RBC) would protect the hepatic level of rat P450 during a massive hemorrhage, compared with plasma expanders and RBC resuscitation. To achieve this, we created 40% hemorrhagic-shock model rats, followed by resuscitation, with use of recombinant human serum albumin, RBCs, and CO-RBCs. At 1 hour after resuscitation, the expressions of hepatic P450 isoforms (1A2, 2C11, 2E1, and 3A2) were significantly decreased in the RBC resuscitation group, compared with the sham group. Such alterations in hepatic P450 significantly resulted in an increase in the plasma concentrations of substrate drugs (caffeine [1A2], tolbutamide [2C11], chlorzoxazone [2E1], and midazolam [3A2]) for each P450 isoform, and thus, the hypnotic action of midazolam could be significantly prolonged. Of interest, the reductions in hepatic P450 activity observed in the RBC group were significantly suppressed by CO-RBC resuscitation, and consequently, the pharmacokinetics of substrate drugs and the pharmacological action of midazolam remained at levels similar to those under sham conditions. These results indicate that CO-RBC resuscitation has considerable potential in terms of achieving safe and useful drug therapy during massive hemorrhages.

  3. Molecular modeling of a T-cell receptor bound to a major histocompatibility complex molecule: implications for T-cell recognition.

    PubMed Central

    Almagro, J. C.; Vargas-Madrazo, E.; Lara-Ochoa, F.; Horjales, E.

    1995-01-01

    The main functions of the T-cell receptor (TCR) involve its specific interaction with short and linear antigenic peptides bound to the major histocompatibility complex (MHC) molecules. In the absence of a 3D structure for TCR and for the TCR/peptide/MHC complex, several attempts to characterize the structural components of the TCR/peptide/MHC interaction have been made. However, this subject is still troublesome. In this paper a computer-based 3D model for a TCR/peptide/MHC complex (5C.C7/moth cytochrome c [MCC] peptide 93-103/I-Ek) was obtained. The complex surface shows a high complementarity between the 5C.C7 structure and the peptide/I-Ek molecule. The mapping of residues involved in the TCR/peptide/MHC interaction shows close agreement with mutational experiments (Jorgensen JL, Reay PA, Ehrich EW, Davis MM, 1992b, Annu Rev Immunol 10:835-873). Moreover, the results are consistent with a recent variability analysis of TCR sequences using three variability indexes (Almagro JC, Zenteno-Cuevas R, Vargas-Madrazo E, Lara-Ochoa F, 1995b, Int J Pept Protein Res 45:180-186). Accordingly, the 3D model of the 5C.C7/MCC peptide 93-103/I-Ek complex provides a framework to generate testable hypotheses about TCR recognition. Thus, starting from this model, the role played by each loop that forms the peptide/MHC binding site of the TCR is discussed. PMID:8528069

  4. Correlation studies between surface tension energy and ionic mobility in silicone - Dammar thin film for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zakaria, R.; Ahmad, A. H.; Taib, M. F. Mohamad; Hassan, O. H.; Yahya, M. Z. A.; Ali, A. M. M.

    2017-09-01

    Organic thin film system consisting of Silicone-dammar (SD) polymer resin was prepared and studied with respect to their electrochemical properties. Dammar which is a local plant resin (Dipterocaupacea sp) was mixed with silicone in various compositions and the two components were modified by using a solvent. A thin film layered on glass slaid was obtained by Doctor Blade method and cured at room temperature. Silicone-dammar with a composition ratio of 80:20 (SD20) showed the highest non-wetting angle at 90.13 degrees however the sample with a composition ratio of 90:10 (SD10) showed the highest surface tension energy at 179.80 J in the contact angle test. Electrochemical Impedance Spectroscopy (EIS) analysis was done to investigate the electron transport and it was found that the SD10 sample provides a good medium for ionic mobility.

  5. Ionic liquids for rechargeable lithium batteries

    SciTech Connect

    Salminen, Justin; Papaiconomou, Nicolas; Kerr, John; Prausnitz,John; Newman, John

    2005-09-29

    We have investigated possible anticipated advantages of ionic-liquid electrolytes for use in lithium-ion batteries. Thermal stabilities and phase behavior were studied by thermal gravimetric analysis and differential scanning calorimetry. The ionic liquids studied include various imidazoliumTFSI systems, pyrrolidiniumTFSI, BMIMPF{sub 6}, BMIMBF{sub 4}, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF{sub 4}-LiBF{sub 4}, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured for various ionic-liquid lithium-salt systems. We show the development of interfacial impedance in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell and we report results from cycling experiments for a Li|BMIMBF{sub 4} + 1 mol/kg LIBF{sub 4}|C cell. The interfacial resistance increases with time and the ionic liquid reacts with the lithium electrode. As expected, imidazolium-based ionic liquids react with lithium electrodes. We seek new ionic liquids that have better chemical stabilities.

  6. High CO2 solubility, permeability and selectivity in ionic liquids with the tetracyanoborate anion

    SciTech Connect

    Mahurin, SM; Hillesheim, PC; Yeary, JS; Jiang, DE; Dai, S

    2012-01-01

    Five different ionic liquids containing the tetracyanoborate anion were synthesized and evaluated for CO2 separation performance. Measured CO2 solubility values were exceptionally high compared to analogous ionic liquids with different anions and ranged from 0.128 mol L-1 atm(-1) to 0.148 mol L-1 atm(-1). In addition, CO2 permeability and CO2/N-2 selectivity values were measured using a supported ionic liquid membrane architecture and the separations performance of the ionic liquid membranes exceeded the Robeson upper bound. These results establish the distinct potential of ionic liquids with the tetracyanoborate, [B(CN)(4)], anion for the separation of CO2.

  7. The effect of intracrystalline and surface-bound osteopontin on the degradation and dissolution of calcium oxalate dihydrate crystals in MDCKII cells.

    PubMed

    Thurgood, Lauren A; Sørensen, Esben S; Ryall, Rosemary L

    2012-02-01

    In vivo, urinary crystals are associated with proteins located within the mineral bulk as well as upon their surfaces. Proteins incarcerated within the mineral phase of retained crystals could act as a defence against urolithiasis by rendering them more vulnerable to destruction by intracellular and interstitial proteases. The aim of this study was to examine the effects of intracrystalline and surface-bound osteopontin (OPN) on the degradation and dissolution of urinary calcium oxalate dihydrate (COD) crystals in cultured Madin Darby canine kidney (MDCK) cells. [(14)C]-oxalate-labelled COD crystals with intracrystalline (IC), surface-bound (SB) and IC + SB OPN, were generated from ultrafiltered (UF) urine containing 0, 1 and 5 mg/L human milk OPN and incubated with MDCKII cells, using UF urine as the binding medium. Crystal size and degradation were assessed using field emission scanning electron microscopy (FESEM) and dissolution was quantified by the release of radioactivity into the culture medium. Crystal size decreased directly with OPN concentration. FESEM examination indicated that crystals covered with SB OPN were more resistant to cellular degradation than those containing IC OPN, whose degree of disruption appeared to be related to OPN concentration. Whether bound to the crystal surface or incarcerated within the mineral interior, OPN inhibited crystal dissolution in direct proportion to its concentration. Under physiological conditions OPN may routinely protect against stone formation by inhibiting the growth of COD crystals, which would encourage their excretion in urine and thereby perhaps partly explain why, compared with calcium oxalate monohydrate crystals, COD crystals are more prevalent in urine, but less common in kidney stones.

  8. Protein-bound Vaccinium fruit polyphenols decrease IgE binding to peanut allergens and RBL-2H3 mast cell degranulation in vitro.

    PubMed

    Plundrich, Nathalie J; Bansode, Rishipal R; Foegeding, E Allen; Williams, Leonard L; Lila, Mary Ann

    2017-04-19

    Peanut allergy is a worldwide health concern. In this study, the natural binding properties of plant-derived polyphenols to proteins was leveraged to produce stable protein-polyphenol complexes comprised of peanut proteins and cranberry (Vaccinium macrocarpon Ait.) or lowbush blueberry (Vaccinium angustifolium Ait.) pomace polyphenols. Protein-bound and free polyphenols were characterized and quantified by multistep extraction of polyphenols from protein-polyphenol complexes. Immunoblotting was performed with peanut-allergic plasma to determine peanut protein-specific IgE binding to unmodified peanut protein, or to peanut protein-polyphenol complexes. In an allergen model system, RBL-2H3 mast cells were exposed to peanut protein-polyphenol complexes and evaluated for their inhibitory activity on ionomycin-induced degranulation (β-hexosaminidase and histamine). Among the evaluated polyphenolic compounds from protein-polyphenol complex eluates, quercetin, - in aglycone or glycosidic form - was the main phytochemical identified to be covalently bound to peanut proteins. Peanut protein-bound cranberry and blueberry polyphenols significantly decreased IgE binding to peanut proteins at p < 0.05 (38% and 31% decrease, respectively). Sensitized RBL-2H3 cells challenged with antigen and ionomycin in the presence of protein-cranberry and blueberry polyphenol complexes showed a significant (p < 0.05) reduction in histamine and β-hexosaminidase release (histamine: 65.5% and 65.8% decrease; β-hexosaminidase: 60.7% and 45.4% decrease, respectively). The modification of peanut proteins with cranberry or blueberry polyphenols led to the formation of peanut protein-polyphenol complexes with significantly reduced allergenic potential. Future trials are warranted to investigate the immunomodulatory mechanisms of these protein-polyphenol complexes and the role of quercetin in their hypoallergenic potential.

  9. 19F NMR analysis of the antimicrobial peptide PGLa bound to native cell membranes from bacterial protoplasts and human erythrocytes.

    PubMed

    Ieronimo, Marco; Afonin, Sergii; Koch, Katja; Berditsch, Marina; Wadhwani, Parvesh; Ulrich, Anne S

    2010-07-07

    (19)F NMR is a unique tool to examine the structure of fluorine-labeled peptides in their native cellular environment, due to an exquisite sensitivity and lack of natural abundance background. For solid-state NMR analysis, we isolated native membranes from erythrocyte ghosts and bacterial protoplasts and prepared them as macroscopically oriented samples. They showed a high purity and quality of alignment according to (31)P NMR, and the membrane-bound antimicrobial peptide PGLa could be detected by (19)F NMR. The characteristic fingerprint splitting of its (19)F reporter group indicated that the peptide helix binds to the native membranes in a surface alignment, albeit with a higher affinity in the prokaryotic than the eukaryotic system.

  10. Effect of a pyrrolidinium zwitterion on charge/discharge cycle properties of Li/LiCoO2 and graphite/Li cells containing an ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Seitaro; Yoshizawa-Fujita, Masahiro; Takeoka, Yuko; Rikukawa, Masahiro

    2016-11-01

    Ionic liquids (ILs) containing zwitterions have been studied as electrolytes for lithium-ion batteries (LIBs). The effects of addition of a pyrrolidinium zwitterion in an IL electrolyte on the thermal and electrochemical stability and charge/discharge properties of Li/LiCoO2 and graphite/Li cells were investigated. The thermal decomposition temperature of the IL electrolyte composed of N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)amide ([P13][FSA])/lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) with 3-(1-butylpyrrolidinium)propane-1-sulfonate (Bpyps) as the zwitterionic additive, the thermal decomposition temperature was about 300 °C. The electrochemical window of [P13][FSA]/LiTFSA/Bpyps was 0-+5.4 V vs. Li/Li+, which was almost identical to that of [P13][FSA]/LiTFSA. Li|electrolyte|LiCoO2 cells containing the IL/Bpyps electrolyte system exhibited high capacities in the cut-off voltage range of 3.0-4.6 V, even after 50 cycles. The increase in the interfacial resistance between the electrolyte and cathode with cycling was suppressed. In the cyclic voltammograms of cells employing a graphite electrode, the intercalation/deintercalation of lithium ions were observed in the range of 0 and + 0.4 V vs. Li/Li+. Further, graphite|electrolyte|Li cells containing [P13][FSA]/LiTFSA/Bpyps exhibited stable charge/discharge cycle behaviour over 50 cycles.

  11. Inhibition of NADPH oxidase 1 activity and blocking the binding of cytosolic and membrane-bound proteins by honokiol inhibit migratory potential of melanoma cells

    PubMed Central

    Prasad, Ram; Kappes, John C.; Katiyar, Santosh K.

    2016-01-01

    Overexpression of NADPH oxidase 1 (Nox1) in melanoma cells is often associated with increased migration/metastasis rate. To develop effective treatment options, we have examined the effect of honokiol, a phytochemical from Magnolia plant, on the migratory potential of human melanoma cell lines (A375, Hs294t, SK-Mel119 and SK-Mel28) and assessed whether Nox1 is the target. Using an in vitro cell migration assay, we observed that treatment of different melanoma cell lines with honokiol for 24 h resulted in a dose-dependent inhibition of cell migration that was associated with reduction in Nox1 expression and reduced levels of oxidative stress. Treatment of cells with N-acetyl-L-cysteine, an anti-oxidant, also inhibited the migration of melanoma cells. Treatment of cells with diphenyleneiodonium chloride, an inhibitor of Nox1, significantly decreased the migration ability of Hs294t and SK-Mel28 cells. Further, we examined the effect of honokiol on the levels of core proteins (p22phox and p47phox) of the NADPH oxidase complex. Treatment of Hs294t and SK-Mel28 cells with honokiol resulted in accumulation of the cytosolic p47phox protein and decreased levels of the membrane-bound p22phox protein, thus blocking their interaction and inhibiting Nox1 activation. Our in vivo bioluminescence imaging data indicate that oral administration of honokiol inhibited the migration/extravasation and growth of intravenously injected melanoma cells in internal body organs, such as liver, lung and kidney in nude mice, and that this was associated with an inhibitory effect on Nox1 activity in these internal organs/tissues. PMID:26760964

  12. Inhibition of NADPH oxidase 1 activity and blocking the binding of cytosolic and membrane-bound proteins by honokiol inhibit migratory potential of melanoma cells.

    PubMed

    Prasad, Ram; Kappes, John C; Katiyar, Santosh K

    2016-02-16

    Overexpression of NADPH oxidase 1 (Nox1) in melanoma cells is often associated with increased migration/metastasis rate. To develop effective treatment options, we have examined the effect of honokiol, a phytochemical from Magnolia plant, on the migratory potential of human melanoma cell lines (A375, Hs294t, SK-Mel119 and SK-Mel28) and assessed whether Nox1 is the target. Using an in vitro cell migration assay, we observed that treatment of different melanoma cell lines with honokiol for 24 h resulted in a dose-dependent inhibition of cell migration that was associated with reduction in Nox1 expression and reduced levels of oxidative stress. Treatment of cells with N-acetyl-L-cysteine, an anti-oxidant, also inhibited the migration of melanoma cells. Treatment of cells with diphenyleneiodonium chloride, an inhibitor of Nox1, significantly decreased the migration ability of Hs294t and SK-Mel28 cells. Further, we examined the effect of honokiol on the levels of core proteins (p22(phox) and p47(phox)) of the NADPH oxidase complex. Treatment of Hs294t and SK-Mel28 cells with honokiol resulted in accumulation of the cytosolic p47(phox) protein and decreased levels of the membrane-bound p22(phox) protein, thus blocking their interaction and inhibiting Nox1 activation. Our in vivo bioluminescence imaging data indicate that oral administration of honokiol inhibited the migration/extravasation and growth of intravenously injected melanoma cells in internal body organs, such as liver, lung and kidney in nude mice, and that this was associated with an inhibitory effect on Nox1 activity in these internal organs/tissues.

  13. The plasma membrane metal-ion transporter ZIP14 contributes to nontransferrin-bound iron uptake by human β-cells.

    PubMed

    Coffey, Richard; Knutson, Mitchell D

    2017-02-01

    The relationship between iron and β-cell dysfunction h