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Sample records for membranes potential implication

  1. The Chemical Potential of Plasma Membrane Cholesterol: Implications for Cell Biology.

    Science.gov (United States)

    Ayuyan, Artem G; Cohen, Fredric S

    2018-02-27

    Cholesterol is abundant in plasma membranes and exhibits a variety of interactions throughout the membrane. Chemical potential accounts for thermodynamic consequences of molecular interactions, and quantifies the effective concentration (i.e., activity) of any substance participating in a process. We have developed, to our knowledge, the first method to measure cholesterol chemical potential in plasma membranes. This was accomplished by complexing methyl-β-cyclodextrin with cholesterol in an aqueous solution and equilibrating it with an organic solvent containing dissolved cholesterol. The chemical potential of cholesterol was thereby equalized in the two phases. Because cholesterol is dilute in the organic phase, here activity and concentration were equivalent. This equivalence allowed the amount of cholesterol bound to methyl-β-cyclodextrin to be converted to cholesterol chemical potential. Our method was used to determine the chemical potential of cholesterol in erythrocytes and in plasma membranes of nucleated cells in culture. For erythrocytes, the chemical potential did not vary when the concentration was below a critical value. Above this value, the chemical potential progressively increased with concentration. We used standard cancer lines to characterize cholesterol chemical potential in plasma membranes of nucleated cells. This chemical potential was significantly greater for highly metastatic breast cancer cells than for nonmetastatic breast cancer cells. Chemical potential depended on density of the cancer cells. A method to alter and fix the cholesterol chemical potential to any value (i.e., a cholesterol chemical potential clamp) was also developed. Cholesterol content did not change when cells were clamped for 24-48 h. It was found that the level of activation of the transcription factor STAT3 increased with increasing cholesterol chemical potential. The cholesterol chemical potential may regulate signaling pathways. Copyright © 2018. Published by

  2. Interaction of the 106-126 prion peptide with lipid membranes and potential implication for neurotoxicity

    International Nuclear Information System (INIS)

    Dupiereux, Ingrid; Zorzi, Willy; Lins, Laurence; Brasseur, Robert; Colson, Pierre; Heinen, Ernst; Elmoualij, Benaissa

    2005-01-01

    Prion diseases are fatal neurodegenerative disorders characterized by the accumulation in the brain of an abnormally misfolded, protease-resistant, and β-sheet rich pathogenic isoform (PrP sc ) of the cellular prion protein (PrP c ). In the present work, we were interested to study the mode of prion protein interaction with the membrane using the 106-126 peptide and small unilamellar lipid vesicles as model. As previously demonstrated, we showed by MTS assay that PrP 106-126 induces alterations in the human neuroblastoma SH-SY5Y cell line. We demonstrated for the first time by lipid-mixing assay and by the liposome vesicle leakage test that PrP 106-126, a non-tilted peptide, induces liposome fusion thus a potential cell membrane destabilization, as supported by membrane integrity assay (LDH). By circular dichroism (CD) analysis we showed that the fusogenic property of PrP 106-126 in the presence of liposome is associated with a predominantly β-sheet structure. These data suggest that the fusogenic property associated with a predominant β-sheet structure exhibited by the prion peptides contributes to the neurotoxicity of these peptides by destabilizing cellular membranes. The latter might be attached at the membrane surface in a parallel orientation as shown by molecular modeling

  3. Control of somatic membrane potential in nociceptive neurons and its implications for peripheral nociceptive transmission

    Science.gov (United States)

    Du, Xiaona; Hao, Han; Gigout, Sylvain; Huang, Dongyang; Yang, Yuehui; Li, Li; Wang, Caixue; Sundt, Danielle; Jaffe, David B.; Zhang, Hailin; Gamper, Nikita

    2014-01-01

    Peripheral sensory ganglia contain somata of afferent fibres conveying somatosensory inputs to the central nervous system. Growing evidence suggests that the somatic/perisomatic region of sensory neurons can influence peripheral sensory transmission. Control of resting membrane potential (Erest) is an important mechanism regulating excitability, but surprisingly little is known about how Erest is regulated in sensory neuron somata or how changes in somatic/perisomatic Erest affect peripheral sensory transmission. We first evaluated the influence of several major ion channels on Erest in cultured small-diameter, mostly capsaicin-sensitive (presumed nociceptive) dorsal root ganglion (DRG) neurons. The strongest and most prevalent effect on Erest was achieved by modulating M channels, K2P and 4-aminopiridine-sensitive KV channels, while hyperpolarization-activated cyclic nucleotide-gated, voltage-gated Na+, and T-type Ca2+ channels to a lesser extent also contributed to Erest. Second, we investigated how varying somatic/perisomatic membrane potential, by manipulating ion channels of sensory neurons within the DRG, affected peripheral nociceptive transmission in vivo. Acute focal application of M or KATP channel enhancers or a hyperpolarization-activated cyclic nucleotide-gated channel blocker to L5 DRG in vivo significantly alleviated pain induced by hind paw injection of bradykinin. Finally, we show with computational modelling how somatic/perisomatic hyperpolarization, in concert with the low-pass filtering properties of the t-junction within the DRG, can interfere with action potential propagation. Our study deciphers a complement of ion channels that sets the somatic Erest of nociceptive neurons and provides strong evidence for a robust filtering role of the somatic and perisomatic compartments of peripheral nociceptive neuron. PMID:25168672

  4. Surface Electrical Potentials of Root Cell Plasma Membranes: Implications for Ion Interactions, Rhizotoxicity, and Uptake

    Directory of Open Access Journals (Sweden)

    Yi-Min Wang

    2014-12-01

    Full Text Available Many crop plants are exposed to heavy metals and other metals that may intoxicate the crop plants themselves or consumers of the plants. The rhizotoxicity of heavy metals is influenced strongly by the root cell plasma membrane (PM surface’s electrical potential (ψ0. The usually negative ψ0 is created by negatively charged constituents of the PM. Cations in the rooting medium are attracted to the PM surface and anions are repelled. Addition of ameliorating cations (e.g., Ca2+ and Mg2+ to the rooting medium reduces the effectiveness of cationic toxicants (e.g., Cu2+ and Pb2+ and increases the effectiveness of anionic toxicants (e.g., SeO42− and H2AsO4−. Root growth responses to ions are better correlated with ion activities at PM surfaces ({IZ}0 than with activities in the bulk-phase medium ({IZ}b (IZ denotes an ion with charge Z. Therefore, electrostatic effects play a role in heavy metal toxicity that may exceed the role of site-specific competition between toxicants and ameliorants. Furthermore, ψ0 controls the transport of ions across the PM by influencing both {IZ}0 and the electrical potential difference across the PM from the outer surface to the inner surface (Em,surf. Em,surf is a component of the driving force for ion fluxes across the PM and controls ion-channel voltage gating. Incorporation of {IZ}0 and Em,surf into quantitative models for root metal toxicity and uptake improves risk assessments of toxic metals in the environment. These risk assessments will improve further with future research on the application of electrostatic theory to heavy metal phytotoxicity in natural soils and aquatic environments.

  5. Modification of trout sperm membranes associated with activation and cryopreservation. Implications for fertilizing potential

    Science.gov (United States)

    Abstract We investigated the effects of two trout sperm activation solutions on sperm physiology and membrane organization prior to and following cryopreservation using flow cytometry and investigated their impact on in vitro fertility. Cryopreservation caused greater phospholipid disorder (high pl...

  6. The nonsteroidal anti-inflammatory drug indomethacin induces heterogeneity in lipid membranes: potential implication for its diverse biological action.

    Directory of Open Access Journals (Sweden)

    Yong Zhou

    2010-01-01

    Full Text Available The nonsteroidal anti-inflammatory drug (NSAID, indomethacin (Indo, has a large number of divergent biological effects, the molecular mechanism(s for which have yet to be fully elucidated. Interestingly, Indo is highly amphiphilic and associates strongly with lipid membranes, which influence localization, structure and function of membrane-associating proteins and actively regulate cell signaling events. Thus, it is possible that Indo regulates diverse cell functions by altering micro-environments within the membrane. Here we explored the effect of Indo on the nature of the segregated domains in a mixed model membrane composed of dipalmitoyl phosphatidyl-choline (di16:0 PC, or DPPC and dioleoyl phosphatidyl-choline (di18:1 PC or DOPC and cholesterol that mimics biomembranes.Using a series of fluorescent probes in a fluorescence resonance energy transfer (FRET study, we found that Indo induced separation between gel domains and fluid domains in the mixed model membrane, possibly by enhancing the formation of gel-phase domains. This effect originated from the ability of Indo to specifically target the ordered domains in the mixed membrane. These findings were further confirmed by measuring the ability of Indo to affect the fluidity-dependent fluorescence quenching and the level of detergent resistance of membranes.Because the tested lipids are the main lipid constituents in cell membranes, the observed formation of gel phase domains induced by Indo potentially occurs in biomembranes. This marked Indo-induced change in phase behavior potentially alters membrane protein functions, which contribute to the wide variety of biological activities of Indo and other NSAIDs.

  7. Relating membrane potential to impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    Eugen Gheorghiu

    2011-12-01

    Full Text Available Non-invasive, label-free assessment of membrane potential of living cells is still a challenging task. The theory linking membrane potential to the low frequency α dispersion exhibited by suspensions of spherical shelled particles (presenting a net charge distribution on the inner side of the shell has been pioneered in our previous studies with emphasis on the permittivity spectra. Whereas α dispersion is related to a rather large variation exhibited by the permittivity spectrum, we report that the related decrement presented by the impedance magnitude spectrum is either extremely small, or occurs (for large cells at very small frequencies (~mHz explaining the lack of experimental bioimpedance data on the matter. We stress that appropriate choice of the parameters (as revealed by the microscopic model may enable access to membrane potential as well as to other relevant parameters when investigating living cells and charged lipid vesicles. We analyse the effect on the low frequency of the permittivity and impedance spectra of: I. Parameters pertaining to cell membrane i.e. (i membrane potential (through the amount of the net charge on the inner side of the membrane, (ii size of the cells/vesicles, (iii conductivity of the membrane; II. Parameters of the extra cellular medium (viscosity and conductivity. The applicability of the study has far reaching implications for basic (life sciences (providing non-invasive access to the dynamics of relevant cell parameters as well as for biosensing applications, e.g. assessment of cytotoxicity of a wide range of stimuli. doi:10.5617/jeb.214 J Electr Bioimp, vol. 2, pp. 93-97, 2011

  8. Versatile membrane deformation potential of activated pacsin.

    Directory of Open Access Journals (Sweden)

    Shih Lin Goh

    Full Text Available Endocytosis is a fundamental process in signaling and membrane trafficking. The formation of vesicles at the plasma membrane is mediated by the G protein dynamin that catalyzes the final fission step, the actin cytoskeleton, and proteins that sense or induce membrane curvature. One such protein, the F-BAR domain-containing protein pacsin, contributes to this process and has been shown to induce a spectrum of membrane morphologies, including tubules and tube constrictions in vitro. Full-length pacsin isoform 1 (pacsin-1 has reduced activity compared to its isolated F-BAR domain, implicating an inhibitory role for its C-terminal Src homology 3 (SH3 domain. Here we show that the autoinhibitory, intramolecular interactions in pacsin-1 can be released upon binding to the entire proline-rich domain (PRD of dynamin-1, resulting in potent membrane deformation activity that is distinct from the isolated F-BAR domain. Most strikingly, we observe the generation of small, homogenous vesicles with the activated protein complex under certain experimental conditions. In addition, liposomes prepared with different methods yield distinct membrane deformation morphologies of BAR domain proteins and apparent activation barriers to pacsin-1's activity. Theoretical free energy calculations suggest bimodality of the protein-membrane system as a possible source for the different outcomes, which could account for the coexistence of energetically equivalent membrane structures induced by BAR domain-containing proteins in vitro. Taken together, our results suggest a versatile role for pacsin-1 in sculpting cellular membranes that is likely dependent both on protein structure and membrane properties.

  9. Membrane potentials of membranes with fixed ionic sites

    NARCIS (Netherlands)

    van den Berg, Albert; van der Wal, P.D.; van der Wal, P.D.; Skowronska-ptasinska, M.; Sudhölter, E.J.R.; Sudholter, Ernst; Bergveld, Piet; Reinhoudt, David

    1990-01-01

    A theoretical model has been developed to simulate the formation of a membrane potential as a function of physically accessible parameters. The description is an extension of the well-known Teorell-Meyer-Sievers (TMS) model, now including free and fixed ionic sites and free and fixed neutral

  10. Analysis of the effects of polyphenols on human spermatozoa reveals unexpected impacts on mitochondrial membrane potential, oxidative stress and DNA integrity; implications for assisted reproductive technology.

    Science.gov (United States)

    Aitken, R J; Muscio, L; Whiting, S; Connaughton, H S; Fraser, B A; Nixon, B; Smith, N D; De Iuliis, G N

    2016-12-01

    The need to protect human spermatozoa from oxidative stress during assisted reproductive technology, has prompted a detailed analysis of the impacts of phenolic compounds on the functional integrity of these cells. Investigation of 16 individual compounds revealed a surprising variety of negative effects including: (i) a loss of mitochondrial membrane potential (Δψm) via mechanisms that were not related to opening of the permeability transition pore but associated with a reduction in thiol expression, (ii) a decline in intracellular reduced glutathione, (iii) the stimulation of pro-oxidant activity including the induction of ROS generation from mitochondrial and non-mitochondrial sources, (iv) stimulation of lipid peroxidation, (v) the generation of oxidative DNA damage, and (vi) impaired sperm motility. For most of the polyphenolic compounds examined, the loss of motility was gradual and highly correlated with the induction of lipid peroxidation (r=0.889). The exception was gossypol, which induced a rapid loss of motility due to its inherent alkylating activity; one consequence of which was a marked reduction in carboxymethyl lysine expression on the sperm tail; a post-translational modification that is known to play a key role in the regulation of sperm movement. The only polyphenols that did not appear to have adverse effects on spermatozoa were resveratrol, genistein and THP at doses below 100μM. These compounds could, therefore, have some therapeutic potential in a clinical setting. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Indole prevents Escherichia coli cell division by modulating membrane potential

    Science.gov (United States)

    Chimerel, Catalin; Field, Christopher M.; Piñero-Fernandez, Silvia; Keyser, Ulrich F.; Summers, David K.

    2012-01-01

    Indole is a bacterial signalling molecule that blocks E. coli cell division at concentrations of 3–5 mM. We have shown that indole is a proton ionophore and that this activity is key to the inhibition of division. By reducing the electrochemical potential across the cytoplasmic membrane of E. coli, indole deactivates MinCD oscillation and prevents formation of the FtsZ ring that is a prerequisite for division. This is the first example of a natural ionophore regulating a key biological process. Our findings have implications for our understanding of membrane biology, bacterial cell cycle control and potentially for the design of antibiotics that target the cell membrane. PMID:22387460

  12. Highly efficient forward osmosis based on porous membranes--applications and implications.

    Science.gov (United States)

    Qi, Saren; Li, Ye; Zhao, Yang; Li, Weiyi; Tang, Chuyang Y

    2015-04-07

    For the first time, forward osmosis (FO) was performed using a porous membrane with an ultrafiltration (UF)-like rejection layer and its feasibility for high performance FO filtration was demonstrated. Compared to traditional FO membranes with dense rejection layers, the UF-like FO membrane was 2 orders of magnitude more permeable. This gave rise to respectable FO water flux even at ultralow osmotic driving force, for example, 7.6 L/m(2).h at an osmotic pressure of merely 0.11 bar (achieved by using a 0.1% poly(sodium 4-styrene-sulfonate) draw solution). The membrane was applied to oil/water separation, and a highly stable FO water flux was achieved. The adoption of porous FO membranes opens a door to many new opportunities, with potential applications ranging from wastewater treatment, valuable product recovery, and biomedical applications. The potential applications and implications of porous FO membranes are addressed in this paper.

  13. Probing glycolytic and membrane potential oscillations in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Poulsen, Allan K.; Andersen, Ann Zahle; Brasen, Jens Christian

    2008-01-01

    , while mitochondrial membrane potential was measured using the fluorescent dye DiOC(2)(3). The results show that, as opposed to NADH and other intermediates in glycolysis, intracellular glucose is not oscillating. Furthermore, oscillations in NADH and membrane potential are inhibited by the ATP...

  14. The effect of membrane diffusion potential change on anionic drugs ...

    African Journals Online (AJOL)

    The effect of membrane potential change on anionic drugs Indomethacin and barbitone induced human erythrocyte shape change and red cell uptake of drug has been studied using microscopy and spectrophotometry techniques respectively. The membrane potential was changed by reducing the extracellular chloride ...

  15. Membrane potential change effects on cationic and neutral drug ...

    African Journals Online (AJOL)

    Membrane potential change effects on cationic and neutral drug - induced erythrocyte shape change and cellular uptake of drugs. A Nwafor, WT Coakley. Abstract. The effect of membrane potential change of the human erythrocytes on cationic drugs tetracaine and chlorpromazine and neutral drug benzyl alcohol induced ...

  16. Nuclear energy: potentiality and implications

    International Nuclear Information System (INIS)

    Bahgat, Gawdat

    2008-01-01

    After a discussion about a broad definition of energy security and about the main challenges facing a potential nuclear renaissance, the article analyses how the European Union and the United States have addressed these challenges. There is no doubt that nuclear power will remain an important component of global energy mix, but it should not be seen as a panacea to the flows in the global energy markets [it

  17. Specific ion effects on membrane potential and the permselectivity of ion exchange membranes

    KAUST Repository

    Geise, Geoffrey M.

    2014-08-26

    © the Partner Organisations 2014. Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The

  18. Zeta-potential of fouled thin film composite membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, K.; Hachisuka, H.; Nakamura, T. [Nitto denko Corp., Ibaraki, (Japan); Kimura, S. [Kogakuin University, Tokyo (Japan). Dept. of Environ. Chemical Engineering; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering

    1999-10-01

    The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It was confirmed that this method could be effectively applied to analyze the fouling of such membranes. It is known that the water flux of membranes drastically decreases as a result of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SEM, EDX and FT-IR, their presence could be clarified by the profile measurements of the surface zeta-potential. The profiles of the membrane surface zeta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring method of surface zeta-potentials allowed us to analyze a very small amount of fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film composite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that this method is easy and effective for the reverse osmosis membrane surface analysis of adsorbed materials such as surfactants. (author)

  19. Potential of membrane processes in management of radioactive liquid waste

    International Nuclear Information System (INIS)

    Kumar, Surender; Jain, Savita; Raj, Kanwar

    2010-01-01

    Various categories of radioactive liquid waste are generated during operations and maintenance of nuclear installations. The potential of membrane processes for the treatment of low-level radioactive liquids is discussed in this paper

  20. Dietary fats and membrane function: implications for metabolism and disease.

    Science.gov (United States)

    Hulbert, A J; Turner, N; Storlien, L H; Else, P L

    2005-02-01

    aspects of mental health. The understanding of dietary lipid profile and its influence on membrane function in relation to metabolic dysregulation has exciting potential for the prevention and treatment of a range of prevalent disease states.

  1. Exploring the potential of commercial polyethylene membranes for desalination by membrane distillation

    KAUST Repository

    Zuo, Jian

    2015-09-26

    The potential of utilizing polyethylene (PE) membranes in membrane distillation (MD) for sea water desalination has been explored in this study. The advantages of using PE membranes are (1) their intrinsic hydrophobicity with low surface energy of 28-33×10N/m, (2) good chemical stability and low thermal conductivity and (3) their commercial availability that may expedite the MD commercialization process. Several commercial PE membranes with different physicochemical properties are employed to study the capability and feasibility of PE membrane application in an MD process. The effect of membrane pore size, porosity, thickness and wetting resistance on MD performance and energy efficiency have been investigated. The PE membranes demonstrate impressive separation performance with permeation fluxes reaching 123.0L/mh for a 3.5wt% sodium chloride (NaCl) feed solution at 80°C. This superior performance surpasses most of the prior commercial and lab-made flat sheet and hollow fiber membranes. A long term MD testing of 100h is also performed to evaluate the durability of PE membranes, and a relatively stable performance is observed during the entire experiment. This long term stability signifies the suitability of PE membranes for MD applications.

  2. Ionization potentials some variations, implications and applications

    CERN Document Server

    Ahrens, L H

    1983-01-01

    Ionization Potentials: Some Variations, Implications and Applications covers several aspects of ionization potential that is a highly significant parameter in controlling the properties of electric discharge. Comprised of 17 chapters, the book covers topic relevant to ionization potentials, such as properties, concepts, and applications, in order to understand and fully comprehend all aspects of ionization potential. The opening chapter is a review of ionization potentials and a discussion of trends and features. The succeeding chapters then tackle complex topics such as the s and p electrons;

  3. Measuring H+ pumping and membrane potential formation in sealed membrane vesicle systems

    DEFF Research Database (Denmark)

    Wielandt, Alex Green; Palmgren, Michael Broberg; Fuglsang, Anja Thoe

    2016-01-01

    is not converted into a product and only moves a few nanometers in space. Here, we describe two methods for the measurement of active proton pumping across lipid bilayers and the concomitant formation of a membrane potential, applying the dyes 9-amino-6-chloro-2-methoxyacridine (ACMA) and oxonol VI. The methods...... are exemplified by assaying transport of the Arabidopsis thaliana plasma membrane H(+)-ATPase (proton pump), which after heterologous expression in Saccharomyces cerevisiae and subsequent purification has been reconstituted in proteoliposomes....

  4. Molecular heterogeneity in glioblastoma: potential clinical implications

    Directory of Open Access Journals (Sweden)

    Nicole Renee Parker

    2015-03-01

    Full Text Available Glioblastomas, (grade 4 astrocytomas, are aggressive primary brain tumors characterized by histopathological heterogeneity. High resolution sequencing technologies have shown that these tumors also feature significant inter-tumoral molecular heterogeneity. Molecular subtyping of these tumors has revealed several predictive and prognostic biomarkers. However, intra-tumoral heterogeneity may undermine the use of single biopsy analysis for determining tumor genotype and has implications for potential targeted therapies. The clinical relevance and theories of tumoral molecular heterogeneity in glioblastoma are discussed.

  5. Membrane, action, and oscillatory potentials in simulated protocells

    Science.gov (United States)

    Syren, R. M.; Fox, S. W.; Przybylski, A. T.; Stratten, W. P.

    1982-01-01

    Electrical membrane potentials, oscillations, and action potentials are observed in proteinoid microspheres impaled with (3 M KCl) microelectrodes. Although effects are of greater magnitude when the vesicles contain glycerol and natural or synthetic lecithin, the results in the purely synthetic thermal protein structures are substantial, attaining 20 mV amplitude in some cases. The results add the property of electrical potential to the other known properties of proteinoid microspheres, in their role as models for protocells.

  6. Membrane Trafficking of Death Receptors: Implications on Signalling

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    Wulf Schneider-Brachert

    2013-07-01

    Full Text Available Death receptors were initially recognised as potent inducers of apoptotic cell death and soon ambitious attempts were made to exploit selective ignition of controlled cellular suicide as therapeutic strategy in malignant diseases. However, the complexity of death receptor signalling has increased substantially during recent years. Beyond activation of the apoptotic cascade, involvement in a variety of cellular processes including inflammation, proliferation and immune response was recognised. Mechanistically, these findings raised the question how multipurpose receptors can ensure selective activation of a particular pathway. A growing body of evidence points to an elegant spatiotemporal regulation of composition and assembly of the receptor-associated signalling complex. Upon ligand binding, receptor recruitment in specialized membrane compartments, formation of receptor-ligand clusters and internalisation processes constitute key regulatory elements. In this review, we will summarise the current concepts of death receptor trafficking and its implications on receptor-associated signalling events.

  7. Induced mitochondrial membrane potential for modeling solitonic conduction of electrotonic signals.

    Directory of Open Access Journals (Sweden)

    R R Poznanski

    Full Text Available A cable model that includes polarization-induced capacitive current is derived for modeling the solitonic conduction of electrotonic potentials in neuronal branchlets with microstructure containing endoplasmic membranes. A solution of the nonlinear cable equation modified for fissured intracellular medium with a source term representing charge 'soakage' is used to show how intracellular capacitive effects of bound electrical charges within mitochondrial membranes can influence electrotonic signals expressed as solitary waves. The elastic collision resulting from a head-on collision of two solitary waves results in localized and non-dispersing electrical solitons created by the nonlinearity of the source term. It has been shown that solitons in neurons with mitochondrial membrane and quasi-electrostatic interactions of charges held by the microstructure (i.e., charge 'soakage' have a slower velocity of propagation compared with solitons in neurons with microstructure, but without endoplasmic membranes. When the equilibrium potential is a small deviation from rest, the nonohmic conductance acts as a leaky channel and the solitons are small compared when the equilibrium potential is large and the outer mitochondrial membrane acts as an amplifier, boosting the amplitude of the endogenously generated solitons. These findings demonstrate a functional role of quasi-electrostatic interactions of bound electrical charges held by microstructure for sustaining solitons with robust self-regulation in their amplitude through changes in the mitochondrial membrane equilibrium potential. The implication of our results indicate that a phenomenological description of ionic current can be successfully modeled with displacement current in Maxwell's equations as a conduction process involving quasi-electrostatic interactions without the inclusion of diffusive current. This is the first study in which solitonic conduction of electrotonic potentials are generated by

  8. Recording membrane potential changes through photoacoustic voltage sensitive dye

    DEFF Research Database (Denmark)

    Zhang, Haichong K.; Kang, Jeeun; Yan, Ping

    2017-01-01

    Monitoring of the membrane potential is possible using voltage sensitive dyes (VSD), where fluorescence intensity changes in response to neuronal electrical activity. However, fluorescence imaging is limited by depth of penetration and high scattering losses, which leads to low sensitivity in viv...

  9. Role of the Transmembrane Potential in the Membrane Proton Leak

    Czech Academy of Sciences Publication Activity Database

    Ruprecht, A.; Sokolenko, E. A.; Beck, V.; Ninnemann, O.; Jabůrek, Martin; Trimbuch, T.; Klishin, S. S.; Ježek, Petr; Skulachev, V. P.; Pohl, E. E.

    2010-01-01

    Roč. 98, č. 8 (2010), s. 1503-1511 ISSN 0006-3495 R&D Projects: GA MŠk ME09018; GA ČR(CZ) GA303/07/0105 Institutional research plan: CEZ:AV0Z50110509 Keywords : proton leak * membrane potential * uncoupling proteins Subject RIV: BO - Biophysics Impact factor: 4.218, year: 2010

  10. Potential applications of electron emission membranes in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Bilevych, Yevgen [Fraunhofer Institute for Reliability and Microintegration (IZM), Berlin (Germany); University of Bonn, Bonn (Germany); Brunner, Stefan E. [Delft University of Technology, Delft (Netherlands); Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Vienna (Austria); Chan, Hong Wah; Charbon, Edoardo [Delft University of Technology, Delft (Netherlands); Graaf, Harry van der, E-mail: vdgraaf@nikhef.nl [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Hagen, Cornelis W. [Delft University of Technology, Delft (Netherlands); Nützel, Gert; Pinto, Serge D. [Photonis, Roden (Netherlands); Prodanović, Violeta [Delft University of Technology, Delft (Netherlands); Rotman, Daan [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); University of Amsterdam, Amsterdam (Netherlands); Santagata, Fabio [State Key Lab for Solid State Lighti Changzhou base, F7 R& D HUB 1, Science and Education Town, Changzhou 213161, Jangsu Province (China); Sarro, Lina; Schaart, Dennis R. [Delft University of Technology, Delft (Netherlands); Sinsheimer, John; Smedley, John [Brookhaven National Laboratory, Upton, NY (United States); Tao, Shuxia; Theulings, Anne M.M.G. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands)

    2016-02-11

    With a miniaturised stack of transmission dynodes, a noise free amplifier is being developed for the detection of single free electrons, with excellent time- and 2D spatial resolution and efficiency. With this generic technology, a new family of detectors for individual elementary particles may become possible. Potential applications of such electron emission membranes in medicine are discussed.

  11. membrane potential change effects on cationic and neutral drug

    African Journals Online (AJOL)

    USER

    NWAFOR A AND COAKLEY W. T. 1Department of Human Physiology, College of Health Sciences University Of Port Harcourt,. Nigeria. 2School of Pure and Applied Biology University of Wales, College of Cardiff, Cathay's Park,. Cardiff, U.K.. The effect of membrane potential change of the human erythrocytes on cationic ...

  12. Potential Applications of Zeolite Membranes in Reaction Coupling Separation Processes

    Science.gov (United States)

    Daramola, Michael O.; Aransiola, Elizabeth F.; Ojumu, Tunde V.

    2012-01-01

    Future production of chemicals (e.g., fine and specialty chemicals) in industry is faced with the challenge of limited material and energy resources. However, process intensification might play a significant role in alleviating this problem. A vision of process intensification through multifunctional reactors has stimulated research on membrane-based reactive separation processes, in which membrane separation and catalytic reaction occur simultaneously in one unit. These processes are rather attractive applications because they are potentially compact, less capital intensive, and have lower processing costs than traditional processes. Therefore this review discusses the progress and potential applications that have occurred in the field of zeolite membrane reactors during the last few years. The aim of this article is to update researchers in the field of process intensification and also provoke their thoughts on further research efforts to explore and exploit the potential applications of zeolite membrane reactors in industry. Further evaluation of this technology for industrial acceptability is essential in this regard. Therefore, studies such as techno-economical feasibility, optimization and scale-up are of the utmost importance.

  13. Potential Applications of Zeolite Membranes in Reaction Coupling Separation Processes

    Directory of Open Access Journals (Sweden)

    Tunde V. Ojumu

    2012-10-01

    Full Text Available Future production of chemicals (e.g., fine and specialty chemicals in industry is faced with the challenge of limited material and energy resources. However, process intensification might play a significant role in alleviating this problem. A vision of process intensification through multifunctional reactors has stimulated research on membrane-based reactive separation processes, in which membrane separation and catalytic reaction occur simultaneously in one unit. These processes are rather attractive applications because they are potentially compact, less capital intensive, and have lower processing costs than traditional processes. Therefore this review discusses the progress and potential applications that have occurred in the field of zeolite membrane reactors during the last few years. The aim of this article is to update researchers in the field of process intensification and also provoke their thoughts on further research efforts to explore and exploit the potential applications of zeolite membrane reactors in industry. Further evaluation of this technology for industrial acceptability is essential in this regard. Therefore, studies such as techno-economical feasibility, optimization and scale-up are of the utmost importance.

  14. The trans-membrane potential of biological membranes in computer simulation

    Czech Academy of Sciences Publication Activity Database

    Melcr, Josef; Timr, Štěpán; Jungwirth, Pavel

    2015-01-01

    Roč. 44, Suppl 1 (2015), S170 ISSN 0175-7571. [EBSA European Biophysics Congress /10./. 18.07.2015-22.07.2015, Dresden] Institutional support: RVO:61388963 Keywords : molecular dynamics * trans-membrane potential Subject RIV: CF - Physical ; Theoretical Chemistry

  15. An Unusual Prohibitin Regulates Malaria Parasite Mitochondrial Membrane Potential

    Directory of Open Access Journals (Sweden)

    Joachim Michael Matz

    2018-04-01

    Full Text Available Summary: Proteins of the stomatin/prohibitin/flotillin/HfIK/C (SPFH family are membrane-anchored and perform diverse cellular functions in different organelles. Here, we investigate the SPFH proteins of the murine malaria model parasite Plasmodium berghei, the conserved prohibitin 1, prohibitin 2, and stomatin-like protein and an unusual prohibitin-like protein (PHBL. The SPFH proteins localize to the parasite mitochondrion. While the conserved family members could not be deleted from the Plasmodium genome, PHBL was successfully ablated, resulting in impaired parasite fitness and attenuated virulence in the mammalian host. Strikingly, PHBL-deficient parasites fail to colonize the Anopheles vector because of complete arrest during ookinete development in vivo. We show that this arrest correlates with depolarization of the mitochondrial membrane potential (ΔΨmt. Our results underline the importance of SPFH proteins in the regulation of core mitochondrial functions and suggest that fine-tuning of ΔΨmt in malarial parasites is critical for colonization of the definitive host. : Matz et al. present an experimental genetics study of an unusual prohibitin-like protein in the malaria parasite and find that it regulates mitochondrial membrane polarity. Ablation of this protein causes almost complete mitochondrial depolarization in the mosquito vector, which, in turn, leads to a block in malaria parasite transmission. Keywords: Plasmodium berghei, malaria, SPFH, prohibitin, stomatin-like protein, mitochondrion, membrane potential, ookinete, transmission

  16. Improved performance of gravity-driven membrane filtration for seawater pretreatment: Implications of membrane module configuration.

    Science.gov (United States)

    Wu, Bing; Christen, Tino; Tan, Hwee Sin; Hochstrasser, Florian; Suwarno, Stanislaus Raditya; Liu, Xin; Chong, Tzyy Haur; Burkhardt, Michael; Pronk, Wouter; Fane, Anthony G

    2017-05-01

    As a low energy and chemical free process, gravity-driven membrane (GDM) filtration has shown a potential for seawater pretreatment in our previous studies. In this study, a pilot submerged GDM reactor (effective volume of 720 L) was operated over 250 days and the permeate flux stabilized at 18.6 ± 1.4 L/m 2 h at a hydrostatic pressure of 40 mbar. This flux was higher than those in the lab-scale GDM reactor (16.3 ± 0.2 L/m 2 h; effective volume of 8.4 L) and in the filtration cell system (2.7 ± 0.6 L/m 2 h; feed side volume of 0.0046 L) when the same flat sheet membrane was used. Interestingly, when the filtration cell was submerged into the GDM reactor, the flux (17.2 L/m 2 h) was comparable to the submerged membrane module. Analysis of cake layer morphology and foulant properties indicated that a thicker but more porous cake layer with less accumulation of organic substances (biopolymers and humics) contributed to the improved permeate flux. This phenomenon was possibly associated with longer residence time of organic substances and sufficient space for the growth, predation, and movement of the eukaryotes in the GDM reactor. In addition, the permeate flux of the submerged hollow fibre membrane increased with decreasing packing density. It is thought that the movement of large-sized eukaryotes could be limited when the space between hollow fibres was reduced. In terms of pretreatment, the GDM systems effectively removed turbidity, viable cells, and transparent exopolymer particles from the feed seawater. Importantly, extending the reactor operation time produced a permeate with less assimilable organic carbon and biopolymers. Thus, the superior quality of the GDM permeate has the potential to alleviate subsequent reverse osmosis membrane fouling for seawater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Electrochemical sensing of membrane potential and enzyme function using gallium arsenide electrodes functionalized with supported membranes.

    Science.gov (United States)

    Gassull, Daniel; Ulman, Abraham; Grunze, Michael; Tanaka, Motomu

    2008-05-08

    We deposit phospholipid monolayers on highly doped p-GaAs electrodes that are precoated with methyl-mercaptobiphenyl monolayers and operate such a biofunctional electrolyte-insulator-semiconductor (EIS) setup as an analogue of a metal-oxide-semiconductor setup. Electrochemical impedance spectra measured over a wide frequency range demonstrate that the presence of a lipid monolayer remarkably slows down the diffusion of ions so that the membrane-functionalized GaAs can be subjected to electrochemical investigations for more than 3 days with no sign of degradation. The biofunctional EIS setup enables us to translate changes in the surface charge density Q and bias potentials Ubias into the change in the interface capacitance Cp. Since Cp is governed by the capacitance of semiconductor space charge region CSC, the linear relationships obtained for 1/Cp2 vs Q and 1/Cp2 vs Ubias suggests that Cp can be used to detect the surface charges with a high sensitivity (1 charge per 18 nm2). Furthermore, the kinetics of phospholipids degradation by phospholipase A2 can also be monitored by a significant decrease in diffusion coefficients through the membrane by a factor of 104. Thus, the operation of GaAs membrane composites established here allows for electrochemical sensing of surface potential and barrier capability of biological membranes in a quantitative manner.

  18. Epilepsy and menopause: potential implications for pharmacotherapy.

    Science.gov (United States)

    Sveinsson, Olafur; Tomson, Torbjörn

    2014-09-01

    Being a woman with epilepsy is not the same as being a man with the disease. There is a complex multidirectional interaction between sex hormones, seizures and antiepileptic drugs (AEDs) with gender-specific implications. Estrogen can be a potent proconvulsant, whereas progesterone is an anticonvulsant in experimental models. It is well established that women with epilepsy can have changes in seizure propensity related to their menstrual cycle (catamenial epilepsy). There is good evidence that the gonadotropin-releasing hormone cell population in the hypothalamus can be affected by seizures originating in the limbic system, possibly leading to anovulatory menses, possibly contributing to lower fertility, and earlier menopause among women with epilepsy. Data on the effects of menopause on epilepsy are scarce. In general, menopause appears to have limited effects on seizure control, with the possible exception of women with catamenial epilepsy who may experience an increase in seizure frequency during perimenopause and a decrease after menopause. Hormone replacement therapy has the potential to increase seizure frequency and thus cannot be recommended for women with epilepsy. Of particular relevance for menopause is the adverse effect on bone mineral density caused by enzyme inducers and other AEDs. In general, there is a remarkable shortage of studies on the impact of menopause on epilepsy and on its implications for epilepsy treatment.

  19. The Amniotic Membrane: Development and Potential Applications - A Review.

    Science.gov (United States)

    Favaron, P O; Carvalho, R C; Borghesi, J; Anunciação, A R A; Miglino, M A

    2015-12-01

    Foetal membranes are essential tissues for embryonic development, playing important roles related to protection, breathing, nutrition and excretion. The amnion is the innermost extraembryonic membrane, which surrounds the foetus, forming an amniotic sac that contains the amniotic fluid (AF). In recent years, the amniotic membrane has emerged as a potential tool for clinical applications and has been primarily used in medicine in order to stimulate the healing of skin and corneal diseases. It has also been used in vaginal reconstructive surgery, repair of abdominal hernia, prevention of surgical adhesions and pericardium closure. More recently, it has been used in regenerative medicine because the amniotic-derived stem cells as well as AF-derived cells exhibit cellular plasticity, angiogenic, cytoprotective, immunosuppressive properties, antitumoural potential and the ability to generate induced pluripotent stem cells. These features make them a promising source of stem cells for cell therapy and tissue engineering. In this review, we discussed the development of the amnion, AF and amniotic cavity in different species, as well as the applicability of stem cells from the amnion and AF in cellular therapy. © 2015 Blackwell Verlag GmbH.

  20. Motoneuron membrane potentials follow a time inhomogeneous jump diffusion process

    DEFF Research Database (Denmark)

    Jahn, Patrick; Berg, Rune W; Hounsgaard, Jørn

    2011-01-01

    much better than an Ornstein-Uhlenbeck process with constant diffusion coefficient. Further, the membrane time constant decreases with increasing depolarization, as expected from the increase in synaptic conductance. The network activity, which the neuron is exposed to, can be reasonably estimated...... to be a threshold version of the nerve output from the network. Moreover, the spiking characteristics are well described by a Poisson spike train with an intensity depending exponentially on the membrane potential.......Stochastic leaky integrate-and-fire models are popular due to their simplicity and statistical tractability. They have been widely applied to gain understanding of the underlying mechanisms for spike timing in neurons, and have served as building blocks for more elaborate models. Especially...

  1. Amphipathic beta-strand mimics as potential membrane disruptive antibiotics.

    Science.gov (United States)

    Watson, Jessica L; Gillies, Elizabeth R

    2009-08-21

    In recent years, there have been increasing numbers of bacterial strains emerging that are resistant to the currently available antibiotics. In the search for new antibiotics, attention has been focused on natural antimicrobial peptides that act by selectively disrupting the membranes of bacterial cells, a mechanism that is thought to be nonconducive to the development of resistance. It is desirable to mimic the structures and activities of these peptides while introducing properties such as resistance to proteolytic degradation, which make molecules more ideal for development as drugs. Described here is the design and synthesis of beta-strand mimetic oligomers based on alternating alpha-amino acids and azacyclohexenone units that segregate cationic lysine and hydrophobic valine side chains on opposite faces of the beta-strand. (1)H NMR dilution studies demonstrated that despite the incorporation of alternating d- and l-amino acids in order to obtain facial amphiphilicity, these oligomers are capable of dimerizing to beta-sheet mimics in a manner similar to the oligomers containing all l-amino acids. The ability of the molecules to disrupt phospholipid vesicles mimicking the membranes of both bacterial and mammalian cells was investigated using a fluorescent dye leakage assay. Several of the oligomers were found to exhibit activity and selectivity for the bacterial over mammalian membranes. Overall, these studies demonstrate the promise of this class of molecules for the development of new potential antibiotics and provide information on the structural features that are important for activity.

  2. Climate change: potential implications for Ireland's biodiversity

    Science.gov (United States)

    Donnelly, Alison

    2018-03-01

    A national biodiversity and climate change adaptation plan is being developed for Ireland by the Department of Communications, Climate Action, and Environment. In order to inform such a plan, it was necessary to review and synthesize some of the recent literature pertaining to the impact of climate change on biodiversity in Ireland. Published research on this topic fell within three broad categories: (i) changes in the timing of life-cycle events (phenology) of plants, birds, and insects; (ii) changes in the geographic range of some bird species; and (iii) changes in the suitable climatic zones of key habitats and species. The synthesis revealed evidence of (i) a trend towards earlier spring activity of plants, birds, and insects which may result in a change in ecosystem function; (ii) an increase in the number of bird species; and (iii) both increases and decreases in the suitable climatic area of key habitats and species, all of which are expected to impact Ireland's future biodiversity. This process identified data gaps and limitations in available information both of which could be used to inform a focused research strategy. In addition, it raises awareness of the potential implications of climate change for biodiversity in Ireland and elsewhere and demonstrates the need for biodiversity conservation plans to factor climate change into future designs.

  3. Indole prevents Escherichia coli cell division by modulating membrane potential

    OpenAIRE

    Chimerel, Catalin; Field, Christopher M.; Pi?ero-Fernandez, Silvia; Keyser, Ulrich F.; Summers, David K.

    2012-01-01

    Indole is a bacterial signalling molecule that blocks E. coli cell division at concentrations of 3?5?mM. We have shown that indole is a proton ionophore and that this activity is key to the inhibition of division. By reducing the electrochemical potential across the cytoplasmic membrane of E. coli, indole deactivates MinCD oscillation and prevents formation of the FtsZ ring that is a prerequisite for division. This is the first example of a natural ionophore regulating a key biological proces...

  4. Retention of Silica Nanoparticles in a Lab-Scale Membrane Bioreactor: Implications for Process Performance and Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Mark Larracas Sibag

    2016-07-01

    Full Text Available In conventional activated sludge (CAS involving aerobic biological processes, the retention of silica nanoparticles (SiO2 NPs has no detrimental effect on chemical oxygen demand (COD and ammonia nitrogen (NH3–N removal. However, for the membrane bioreactor (MBR system, which is also based on the activated sludge process in addition to the membrane separation process, it has implications not only on the process performance but also on membrane fouling. To investigate these two implications in lab-scale experiments, we continuously operated a control MBR and two experimental MBRs, in which the 28 nm SiO2 NPs and 144 nm SiO2 NPs were added separately to the influent at a final concentration of 100 mg/L. Although the retention of SiO2 NPs in the MBR, as confirmed by dynamic light scattering (DLS analysis, did not compromise the COD and NH3–N removal, it resulted in substantial increases in the transmembrane pressure (TMP suggesting the onset of membrane fouling. Analyses by batch-dead end filtration revealed the same fouling trend as observed during the continuous MBR experiments; membrane fouling is aggravated in the presence of SiO2 NPs. This was evident from permeate flux decline of between 30% and 74% at very low TMP (5 kPa and the further increases in the total resistance.

  5. Effect of Adsorbed Protein on the Hydraulic Permeability, Membrane and Streaming Potential Values Measured across a Microporous Membrane

    DEFF Research Database (Denmark)

    Benavente, Juana; Jonsson, Gunnar Eigil

    1998-01-01

    The effect of the adsorption of a protein, bovine serum albumin (BSA), on the membrane potential, flux reduction and streaming potential measured across a microporous polysulphone membrane with different NaCl solutions and pH values is studied. From electrokinetic phenomena, information about...... as a "composite" or two-layer membrane, and a comparison of the results obtained with both microporous polysulphone and "composite" (microporous + BSA layer) membranes could permit us to determine some parameters related to the protein sublayer. (C) 1998 Elsevier Science B.V....

  6. Fouling mitigation of anion exchange membrane by zeta potential control.

    Science.gov (United States)

    Park, Jin-Soo; Lee, Hong-Joo; Choi, Seok-Ju; Geckeler, Kurt E; Cho, Jaeweon; Moon, Seung-Hyeon

    2003-03-15

    The feasibility of fouling mitigation of anion exchange membranes (AEMs) in the presence of humate was studied by adding three different types of water-soluble polymers, i.e., poly(acrylic acid) (PAA), poly(vinyl alcohol) (PVA), and poly(ethylene imine) (PEI), during electrodialysis (ED) desalination. Measurement of zeta potential of the humate used in this study showed highly negative potential (about -30 mV), implying that the humate had a strong fouling potential on the AEMs in ED. Of the three water-soluble polymers, PEI showed a positive zeta potential (about +14 mV) and is able to form an interpolymer complex with the humate. PAA and PVA hardly formed interpolymer complexes with humate due to electrostatic repulsion. The PEI-humate mixture with a volume ratio of 1:20 (PEI:humate) showed zero zeta potential, and a complexed humate with zero surface charge was formed, resulting in no fouling effects on the AEMs. Accordingly, the desalting ED experiments with PEI showed improved ED performance. Further, black colloids formed in the mixture did not cause the cell resistance to increase.

  7. Biochemical evidence of the interactions of membrane type-1 matrix metalloproteinase (MT1-MMP) with adenine nucleotide translocator (ANT): potential implications linking proteolysis with energy metabolism in cancer cells.

    Science.gov (United States)

    Radichev, Ilian A; Remacle, Albert G; Sounni, Nor Eddine; Shiryaev, Sergey A; Rozanov, Dmitri V; Zhu, Wenhong; Golubkova, Natalya V; Postnova, Tatiana I; Golubkov, Vladislav S; Strongin, Alex Y

    2009-04-28

    Invasion-promoting MT1-MMP (membrane type-1 matrix metalloproteinase) is a key element in cell migration processes. To identify the proteins that interact and therefore co-precipitate with this proteinase from cancer cells, we used the proteolytically active WT (wild-type), the catalytically inert E240A and the C-end truncated (tailless; DeltaCT) MT1-MMP-FLAG constructs as baits. The identity of the pulled-down proteins was determined by LC-MS/MS (liquid chromatography tandem MS) and then confirmed by Western blotting using specific antibodies. We determined that, in breast carcinoma MCF cells (MCF-7 cells), ANT (adenine nucleotide translocator) efficiently interacted with the WT, E240A and DeltaCT constructs. The WT and E240A constructs also interacted with alpha-tubulin, an essential component of clathrin-mediated endocytosis. In turn, tubulin did not co-precipitate with the DeltaCT construct because of the inefficient endocytosis of the latter, thus suggesting a high level of selectivity of our test system. To corroborate these results, we then successfully used the ANT2-FLAG construct as a bait to pull-down MT1-MMP, which was naturally produced by fibrosarcoma HT1080 cells. We determined that the presence of the functionally inert catalytic domain alone was sufficient to cause the proteinase to interact with ANT2, thus indicating that there is a non-proteolytic mode of these interactions. Overall, it is tempting to hypothesize that by interacting with pro-invasive MT1-MMP, ANT plays a yet to be identified role in a coupling mechanism between energy metabolism and pericellular proteolysis in migrating cancer cells.

  8. Simultaneous evaluation of plasma membrane integrity, acrosomal integrity, and mitochondrial membrane potential in bovine spermatozoa by flow cytometry.

    Science.gov (United States)

    Kanno, Chihiro; Kang, Sung-Sik; Kitade, Yasuyuki; Yanagawa, Yojiro; Takahashi, Yoshiyuki; Nagano, Masashi

    2016-08-01

    The present study aimed to develop an objective evaluation procedure to estimate the plasma membrane integrity, acrosomal integrity, and mitochondrial membrane potential of bull spermatozoa simultaneously by flow cytometry. Firstly, we used frozen-thawed semen mixed with 0, 25, 50, 75 or 100% dead spermatozoa. Semen was stained using three staining solutions: SYBR-14, propidium iodide (PI), and phycoerythrin-conjugated peanut agglutinin (PE-PNA), for the evaluation of plasma membrane integrity and acrosomal integrity. Then, characteristics evaluated by flow cytometry and by fluorescence microscopy were compared. Characteristics of spermatozoa (viability and acrosomal integrity) evaluated by flow cytometry and by fluorescence microscopy were found to be similar. Secondly, we attempted to evaluate the plasma membrane integrity, acrosomal integrity, and also mitochondrial membrane potential of spermatozoa by flow cytometry using conventional staining with three dyes (SYBR-14, PI, and PE-PNA) combined with MitoTracker Deep Red (MTDR) staining (quadruple staining). The spermatozoon characteristics evaluated by flow cytometry using quadruple staining were then compared with those of staining using SYBR-14, PI, and PE-PNA and staining using SYBR-14 and MTDR. There were no significant differences in all characteristics (viability, acrosomal integrity, and mitochondrial membrane potential) evaluated by quadruple staining and the other procedures. In conclusion, quadruple staining using SYBR-14, PI, PE-PNA, and MTDR for flow cytometry can be used to evaluate the plasma membrane integrity, acrosomal integrity, and mitochondrial membrane potential of bovine spermatozoa simultaneously.

  9. Membrane assisted fluidized bed reactors: Potentials and hurdles

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; Heinrich, S.; Mörl, L.; van Sint Annaland, M.; Kuipers, J.A.M.

    2007-01-01

    Recent advances in the development of more stable membranes with increased permeance have significantly enhanced the possibilities for integrating membranes into catalytic reactors in order to achieve a major increase in reactor performance by process integration and process intensification. Several

  10. Use of Membrane Potential to Achieve Transmembrane Modification with an Artificial Receptor.

    Science.gov (United States)

    Hatanaka, Wataru; Kawaguchi, Miki; Sun, Xizheng; Nagao, Yusuke; Ohshima, Hiroyuki; Hashida, Mitsuru; Higuchi, Yuriko; Kishimura, Akihiro; Katayama, Yoshiki; Mori, Takeshi

    2017-02-15

    We developed a strategy to modify cell membranes with an artificial transmembrane receptor. Coulomb force on the receptor, caused by the membrane potential, was used to achieve membrane penetration. A hydrophobically modified cationic peptide was used as a membrane potential sensitive region that was connected to biotin through a transmembrane oligoethylene glycol (OEG) chain. This artificial receptor gradually disappeared from the cell membrane via penetration despite the presence of a hydrophilic OEG chain. However, when the receptor was bound to streptavidin (SA), it remained on the cell membrane because of the large and hydrophilic nature of SA.

  11. Integrity of the plasma membrane, the acrosomal membrane, and the mitochondrial membrane potential of sperm in Nelore bulls from puberty to sexual maturity

    Directory of Open Access Journals (Sweden)

    L.S.L.S. Reis

    2016-06-01

    Full Text Available ABSTRACT This study evaluated the plasma membrane integrity, acrosomal membrane integrity, and mitochondrial membrane potential of Nelore bull sperm from early puberty to early sexual maturity and their associations with sperm motility and vigor, the mass motility of the spermatozoa (wave motion, scrotal circumference, and testosterone. Sixty Nelore bulls aged 18 to 19 months were divided into four lots (n=15 bulls/lot and evaluated over 280 days. Semen samples, collected every 56 days by electroejaculation, were evaluated soon after collection for motility, vigor and wave motion under an optical microscope. Sperm membrane integrity, acrosomal integrity, and mitochondrial activity were evaluated under a fluorescent microscope using probe association (FITC-PSA, PI, JC-1, H342. The sperm were classified into eight integrity categories depending on whether they exhibited intact or damaged membranes, an intact or damaged acrosomal membrane, and high or low mitochondrial potential. The results show that bulls have a low amount of sperm with intact membranes at puberty, and the sperm show low motility, vigor, and wave motion; however, in bulls at early sexual maturity, the integrity of the sperm membrane increased significantly. The rate of sperm membrane damage was negatively correlated with motility, vigor, wave motion, and testosterone in the bulls, and a positive correlation existed between sperm plasma membrane integrity and scrotal circumference. The integrity of the acrosomal membrane was not influenced by puberty. During puberty and into early sexual maturity, bulls show low sperm mitochondrial potential, but when bulls reached sexual maturity, high membrane integrity with high mitochondrial potential was evident.

  12. Membrane-mediated action of the endocannabinoid anandamide on membrane proteins: implications for understanding the receptor-independent mechanism

    Science.gov (United States)

    Medeiros, Djalma; Silva-Gonçalves, Laíz Da Costa; da Silva, Annielle Mendes Brito; Dos Santos Cabrera, Marcia Perez; Arcisio-Miranda, Manoel

    2017-01-01

    Endocannabinoids are amphiphilic molecules that play crucial neurophysiological functions acting as lipid messengers. Antagonists and knockdown of the classical CB1 and CB2 cannabinoid receptors do not completely abolish many endocannabinoid activities, supporting the idea of a mechanism independent of receptors whose mode of action remains unclear. Here we combine gramicidin A (gA) single channel recordings and membrane capacitance measurements to investigate the lipid bilayer-modifying activity of endocannabinoids. Single channel recordings show that the incorporation of endocannabinoids into lipid bilayers reduces the free energy necessary for gramicidin channels to transit from the monomeric to the dimeric conformation. Membrane capacitance demonstrates that the endocannabinoid anandamide has limited effects on the overall structure of the lipid bilayers. Our results associated with the theory of membrane elastic deformation reveal that the action of endocannabinoids on membrane proteins can involve local adjustments of the lipid/protein hydrophobic interface. The current findings shed new light on the receptor-independent mode of action of endocannabinoids on membrane proteins, with important implications towards their neurobiological function.

  13. Mammalian gamete plasma membranes re-assessments and reproductive implications

    Science.gov (United States)

    Establishment of the diploid status occurs with the fusion of female and male gametes. Both the mammalian oocyte and spermatozoa are haploid cells surrounded with plasma membranes that are rich in various proteins playing a crucial role during fertilization. Fertilization is a complex and ordered st...

  14. Medicare Part D Roulette, Potential Implications of Random..

    Data.gov (United States)

    U.S. Department of Health & Human Services — Medicare Part D Roulette, Potential Implications of Random Assignment and Plan Restrictions Dual-eligible (Medicare and Medicaid) beneficiaries are randomly assigned...

  15. An averaged polarizable potential for multiscale modeling in phospholipid membranes

    DEFF Research Database (Denmark)

    Witzke, Sarah; List, Nanna Holmgaard; Olsen, Jógvan Magnus Haugaard

    2017-01-01

    is underlined for the description of larger assemblies of lipids, that is, membranes. In conclusion, we find that specially developed polarizable parameters are needed for embedding calculations in membranes, while common non-polarizable point-charge force fields usually perform well enough for structural...

  16. Signature of a Nonharmonic Potential as Revealed from a Consistent Shape and Fluctuation Analysis of an Adherent Membrane

    Directory of Open Access Journals (Sweden)

    Daniel Schmidt

    2014-05-01

    Full Text Available The interaction of fluid membranes with a scaffold, which can be a planar surface or a more complex structure, is intrinsic to a number of systems from artificial supported bilayers and vesicles to cellular membranes. In principle, these interactions can be either discrete and protein mediated, or continuous. In the latter case, they emerge from ubiquitous intrinsic surface interaction potentials as well as nature-designed steric contributions of the fluctuating membrane or from the polymers of the glycocalyx. Despite the fact that these nonspecific potentials are omnipresent, their description has been a major challenge from experimental and theoretical points of view. Here, we show that a full understanding of the implications of the continuous interactions can be achieved only by expanding the standard superposition models commonly used to treat these types of systems, beyond the usual harmonic level of description. Supported by this expanded theoretical framework, we present three independent, yet mutually consistent, experimental approaches to measure the interaction potential strength and the membrane tension. Upon explicitly taking into account the nature of shot noise as well as the nature of finite experimental resolution, excellent agreement with the augmented theory is obtained, which finally provides a coherent view of the behavior of the membrane in the vicinity of a scaffold.

  17. Microbial transformation of biomacromolecules in a membrane bioreactor: implications for membrane fouling investigation.

    Directory of Open Access Journals (Sweden)

    Zhongbo Zhou

    Full Text Available BACKGROUND: The complex characteristics and unclear biological fate of biomacromolecules (BMM, including colloidal and soluble microbial products (SMP, extracellular polymeric substances (EPS and membrane surface foulants (MSF, are crucial factors that limit our understanding of membrane fouling in membrane bioreactors (MBRs. FINDINGS: In this study, the microbial transformation of BMM was investigated in a lab-scale MBR by well-controlled bioassay tests. The results of experimental measurements and mathematical modeling show that SMP, EPS, and MSF had different biodegradation behaviors and kinetic models. Based on the multi-exponential G models, SMP were mainly composed of slowly biodegradable polysaccharides (PS, proteins (PN, and non-biodegradable humic substances (HS. In contrast, EPS contained a large number of readily biodegradable PN, slowly biodegradable PS and HS. MSF were dominated by slowly biodegradable PS, which had a degradation rate constant similar to that of SMP-PS, while degradation behaviors of MSF-PN and MSF-HS were much more similar to those of EPS-PN and EPS-HS, respectively. In addition, the large-molecular weight (MW compounds (>100 kDa in BMM were found to have a faster microbial transformation rate compared to the small-MW compounds (<5 kDa. The parallel factor (PARAFAC modeling of three-dimensional fluorescence excitation-emission matrix (EEM spectra showed that the tryptophan-like PN were one of the major fractions in the BMM and they were more readily biodegradable than the HS. Besides microbial mineralization, humification and hydrolysis could be viewed as two important biotransformation mechanisms of large-MW compounds during the biodegradation process. SIGNIFICANCE: The results of this work can aid in tracking the origin of membrane foulants from the perspective of the biotransformation behaviors of SMP, EPS, and MSF.

  18. Membrane Currents in Airway Smooth Muscle: Mechanisms and Therapeutic Implications

    Directory of Open Access Journals (Sweden)

    Luke J Janssen

    1997-01-01

    Full Text Available Electrophysiological and pharmacological techniques were used to characterize the membrane conductance changes underlying spasmogen-evoked depolarization in airway smooth muscle (ASM. Changes included a transient activation of chloride ion channels and prolonged suppression of potassium ion channels; both changes are triggered by release of internally sequestered calcium ion and in turn cause opening of voltage-dependent calcium channels. The resultant influx of calcium ions contributes to contraction as well as to refilling of the internal calcium ion pool. Bronchodilators, on the other hand, act in part through activation of potassium channels, with consequent closure of calcium channels. The tools used to study ion channels in ASM are described, and the investigations of the roles of ion channels in ASM physiology (autacoid-evoked depolarization and hyperpolarization and pathophysiology (airway hyperresponsiveness are summarized. Finally, how the relationship between ion channels and ASM function/dysfunction may relate to the treatment of asthma and related breathing disorders is discussed.

  19. Cytosol-dependent membrane fusion in ER, nuclear envelope and nuclear pore assembly: biological implications.

    Science.gov (United States)

    Rafikova, Elvira R; Melikov, Kamran; Chernomordik, Leonid V

    2010-01-01

    Endoplasmic reticulum and nuclear envelope rearrangements after mitosis are often studied in the reconstitution system based on Xenopus egg extract. In our recent work we partially replaced the membrane vesicles in the reconstitution mix with protein-free liposomes to explore the relative contributions of cytosolic and transmembrane proteins. Here we discuss our finding that cytosolic proteins mediate fusion between membranes lacking functional transmembrane proteins and the role of membrane fusion in endoplasmic reticulum and nuclear envelope reorganization. Cytosol-dependent liposome fusion has allowed us to restore, without adding transmembrane nucleoporins, functionality of nuclear pores, their spatial distribution and chromatin decondensation in nuclei formed at insufficient amounts of membrane material and characterized by only partial decondensation of chromatin and lack of nuclear transport. Both the mechanisms and the biological implications of the discovered coupling between spatial distribution of nuclear pores, chromatin decondensation and nuclear transport are discussed.

  20. On-line measurements of oscillating mitochondrial membrane potential in glucose-fermenting Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Andersen, Ann Zahle; Poulsen, Allan K; Brasen, Jens Christian

    2007-01-01

    We employed the fluorescent cyanine dye DiOC(2)(3) to measure membrane potential in semi-anaerobic yeast cells under conditions where glycolysis was oscillating. Oscillations in glycolysis were studied by means of the naturally abundant nicotinamide adenine dinucleotide (NADH). We found...... studies showed that glycolytic oscillations perturb the mitochondrial membrane potential and that the mitochondria do not have any controlling effect on the dynamics of glycolysis under these conditions. Depolarization of the mitochondrial membrane by addition of FCCP quenched mitochondrial membrane...... potential oscillations and delocalized DiOC(2)(3), while glycolysis continued to oscillate unaffected....

  1. K+ transport and membrane potentials in isolated rat parotid acini

    Energy Technology Data Exchange (ETDEWEB)

    Nauntofte, B.; Dissing, S.

    1988-10-01

    42K+ transport properties of isolated rat parotid acini were characterized concomitant with measurements of membrane potentials (Em) by means of the fluorescent dye diSC3-(5). In unstimulated acini suspended in a 5 mM K+ buffer, Em was governed by the K+ and Cl- gradients and amounted to about -59 mV, a value that remained unaffected on cholinergic stimulation. In unstimulated acini, 42K+ influx was largely mediated by the Na+-K+ pump, and the residual influxes were mediated by a bumetanide-sensitive component (cotransport system) and by K+ channels. Efflux of 42K+ was largely mediated by a bumetanide-sensitive component and by K+ channels. In the unstimulated state, the cotransport system was mediating K+-K+ exchange without contributing to the net uptake of K+. Within 10 s after stimulation, a approximately 10-fold increase in the acinar K+ conductance (gK) occurred, resulting in a rapid net efflux of K+ that amounted to approximately 3.8 mmol.l cells-1.s-1. Measurements of 42K+ fluxes as a function of the external K+ concentration revealed that in the stimulated state gK increases when external K+ is raised from 0.7 to 10 mM, consistent with an activation of acinar gK by the binding of external K+ to the channel. 42K+ flux ratios as well as the effect of the K+ channel inhibitor from scorpion venom (LQV) suggest that approximately 90% of K+ transport in the stimulated state is mediated by ''maxi'' K+ channels.

  2. K+ transport and membrane potentials in isolated rat parotid acini

    International Nuclear Information System (INIS)

    Nauntofte, B.; Dissing, S.

    1988-01-01

    42K+ transport properties of isolated rat parotid acini were characterized concomitant with measurements of membrane potentials (Em) by means of the fluorescent dye diSC3-(5). In unstimulated acini suspended in a 5 mM K+ buffer, Em was governed by the K+ and Cl- gradients and amounted to about -59 mV, a value that remained unaffected on cholinergic stimulation. In unstimulated acini, 42K+ influx was largely mediated by the Na+-K+ pump, and the residual influxes were mediated by a bumetanide-sensitive component (cotransport system) and by K+ channels. Efflux of 42K+ was largely mediated by a bumetanide-sensitive component and by K+ channels. In the unstimulated state, the cotransport system was mediating K+-K+ exchange without contributing to the net uptake of K+. Within 10 s after stimulation, a approximately 10-fold increase in the acinar K+ conductance (gK) occurred, resulting in a rapid net efflux of K+ that amounted to approximately 3.8 mmol.l cells-1.s-1. Measurements of 42K+ fluxes as a function of the external K+ concentration revealed that in the stimulated state gK increases when external K+ is raised from 0.7 to 10 mM, consistent with an activation of acinar gK by the binding of external K+ to the channel. 42K+ flux ratios as well as the effect of the K+ channel inhibitor from scorpion venom (LQV) suggest that approximately 90% of K+ transport in the stimulated state is mediated by ''maxi'' K+ channels

  3. Alterations in membrane trafficking and pathophysiological implications in lysosomal storage disorders.

    Science.gov (United States)

    Kuech, Eva-Maria; Brogden, Graham; Naim, Hassan Y

    2016-11-01

    Lysosomal storage disorders are a heterogeneous group of more than 50 distinct inborn metabolic diseases affecting about 1 in 5000 to 7000 live births. The diseases often result from mutations followed by functional deficiencies of enzymes or transporters within the acidic environment of the lysosome, which mediate the degradation of a wide subset of substrates, including glycosphingolipids, glycosaminoglycans, cholesterol, glycogen, oligosaccharides, peptides and glycoproteins, or the export of the respective degradation products from the lysosomes. The progressive accumulation of uncleaved substrates occurs in multiple organs and finally causes a broad spectrum of different pathologies including visceral, neurological, skeletal and hematologic manifestations. Besides deficient lysosomal enzymes and transporters other defects may lead to lysosomal storage disorders, including activator defects, membrane defects or defects in modifier proteins. In this review we concentrate on four different lysosomal storage disorders: Niemann-Pick type C, Fabry disease, Gaucher disease and Pompe disease. While the last three are caused by defective lysosomal hydrolases, Niemann-Pick type C is caused by the inability to export LDL-derived cholesterol out of the lysosome. We want to emphasise potential implications of membrane trafficking defects on the pathology of these diseases, as many mutations interfere with correct lysosomal protein trafficking and alter cellular lipid homeostasis. Current therapeutic strategies are summarised, including substrate reduction therapy as well as pharmacological chaperone therapy which directly aim to improve folding and lysosomal transport of misfolded mutant proteins. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  4. EFFECT OF HIGH PH ON THE PLASMA-MEMBRANE POTENTIAL AND CONDUCTANCE IN ELODEA-DENSA

    NARCIS (Netherlands)

    MIEDEMA, H; FELLE, H; PRINS, HBA

    In leaves of Elodea densa the membrane potential measured in light equals the equilibrium potential of H+ on the morphological upper plasma membrane. The apoplastic pH on the upper side of the leaf is as high as 10.5-11.0, which indicates that alkaline pH induces an increased H+ permeability of the

  5. Normal chemotaxis in Dictyostelium discoideum cells with a depolarized plasma membrane potential

    NARCIS (Netherlands)

    Duijn, Bert van; Vogelzang, Sake A.; Ypey, Dirk L.; Molen, Loek G. van der; Haastert, Peter J.M. van

    1990-01-01

    We examined a possible role for the plasma membrane potential in signal transduction during cyclic AMP-induced chemotaxis in the cellular slime mold Dictyostelium discoideum. Chemotaxis, cyclic GMP and cyclic AMP responses in cells with a depolarized membrane potential were measured. Cells can be

  6. Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes

    DEFF Research Database (Denmark)

    Molina, C.E.; Gesser, Hans; Llach, A.

    2007-01-01

    Application of the current-clamp technique in rainbow trout atrial myocytes has yielded resting membrane potentials that are incompatible with normal atrial function. To investigate this paradox, we recorded the whole membrane current (Im) and compared membrane potentials recorded in isolated...... cardiac myocytes and multicellular preparations. Atrial tissue and ventricular myocytes had stable resting potentials of -87 ± 2 mV and -83.9 ± 0.4 mV, respectively. In contrast, 50 out of 59 atrial myocytes had unstable depolarized membrane potentials that were sensitive to the holding current. We...... hypothesized that this is at least partly due to a small slope conductance of Im around the resting membrane potential in atrial myocytes. In accordance with this hypothesis, the slope conductance of Im was about sevenfold smaller in atrial than in ventricular myocytes. Interestingly, ACh increased Im at -120...

  7. The outer limiting membrane (OLM revisited: clinical implications

    Directory of Open Access Journals (Sweden)

    S Omri

    2010-03-01

    Full Text Available S Omri1,2,3, B Omri1,2,3, M Savoldelli1,2,3,4, L Jonet1,2,3, B Thillaye-Goldenberg1,2,3, G Thuret5, P Gain5, J C Jeanny1,2,3, P Crisanti1,2,3, Francine Behar-Cohen1,2,3,41INSERM, U872 Physiopathology of ocular diseases: Therapeutic innovations, Paris, France; 2Centre de Recherche des Cordeliers, Université Pierre et Marie Curie – Paris6, Paris, France; 3Université Paris Descartes, Paris, France; 4Department of Ophthalmology, Hôtel-Dieu de Paris, France; 5Department of Ophthalmology, Bellevue Hospital, University of Saint-Etienne, FrancePurpose: The outer limiting membrane (OLM is considered to play a role in maintaining the structure of the retina through mechanical strength. However, the observation of junction proteins located at the OLM and its barrier permeability properties may suggest that the OLM may be part of the retinal barrier.Material and methods: Normal and diabetic rat, monkey, and human retinas were used to analyze junction proteins at the OLM. Proteome analyses were performed using immunohistochemistry on sections and flat-mounted retinas and western blotting on protein extracts obtained from laser microdissection of the photoreceptor layers. Semi-thin and ultrastructure analyses were also reported.Results: In the rat retina, in the subapical region zonula occludens-1 (ZO-1, junction adhesion molecule (JAM, an atypical protein kinase C, is present and the OLM shows dense labeling of occludin, JAM, and ZO-1. The presence of occludin has been confirmed using western blot analysis of the microdissected OLM region. In diabetic rats, occludin expression is decreased and glial cells junctions are dissociated. In the monkey retina, occludin, JAM, and ZO-1 are also found in the OLM. Junction proteins have a specific distribution around cone photoreceptors and Müller glia. Ultrastructural analyses suggest that structures like tight junctions may exist between retinal glial Müller cells and photoreceptors.Conclusions: In the OLM

  8. The Effect of the Pore Entrance on Particle Motion in Slit Pores: Implications for Ultrathin Membranes.

    Science.gov (United States)

    Delavari, Armin; Baltus, Ruth

    2017-08-10

    Membrane rejection models generally neglect the effect of the pore entrance on intrapore particle transport. However, entrance effects are expected to be particularly important with ultrathin membranes, where membrane thickness is typically comparable to pore size. In this work, a 2D model was developed to simulate particle motion for spherical particles moving at small Re and infinite Pe from the reservoir outside the pore into a slit pore. Using a finite element method, particles were tracked as they accelerated across the pore entrance until they reached a steady velocity in the pore. The axial position in the pore where particle motion becomes steady is defined as the particle entrance length (PEL). PELs were found to be comparable to the fluid entrance length, larger than the pore size and larger than the thickness typical of many ultrathin membranes. Results also show that, in the absence of particle diffusion, hydrodynamic particle-membrane interactions at the pore mouth result in particle "funneling" in the pore, yielding cross-pore particle concentration profiles focused at the pore centerline. The implications of these phenomena on rejection from ultrathin membranes are examined.

  9. A Pathogenic Potential of Acinetobacter baumannii-Derived Membrane Vesicles

    Directory of Open Access Journals (Sweden)

    Jong Suk Jin

    2011-12-01

    Full Text Available Acinetobacter baumannii secretes outer membrane vesicles (OMVs. A. baumannii OMVs deliver many virulence factors to host cells and then induce cytotoxicity and innate immune response. OMVs secreted from bacteria contribute directly to host pathology during A. baumannii infection.

  10. Bone regeneration potential of sub-microfibrous membranes with ...

    African Journals Online (AJOL)

    Conclusion: The results indicate that biodegradable PCL sub-microfibrous membrane produced by electrospinning process seems to have excellent biocompatibility, and may be used as a scaffold for bone tissue engineering. Keywords: Biocompatibility, Hard tissue, Biomaterial availability, Bone remodeling, Polylactic acid, ...

  11. Membrane potential plays a dual role for chloride transport across toad skin

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Rasmussen, B E

    1983-01-01

    The Cl- -current through toad skin epithelium depends on the potential in a way consistent with a potential-controlled Cl- permeability. Computer analysis of the Koefoed-Johnsen Ussing two-membrane model provided with constant membrane permeabilities indicates that the voltage- and time-dependent......The Cl- -current through toad skin epithelium depends on the potential in a way consistent with a potential-controlled Cl- permeability. Computer analysis of the Koefoed-Johnsen Ussing two-membrane model provided with constant membrane permeabilities indicates that the voltage- and time...... resemble experimental observations. This extension of the classic frog skin model implies that the Cl- permeability is activated by a voltage change caused by the inward Na+ current through the apical membrane....

  12. The amphiphilic nature of saponins and their effects on artificial and biological membranes and potential consequences for red blood and cancer cells.

    Science.gov (United States)

    Lorent, Joseph H; Quetin-Leclercq, Joëlle; Mingeot-Leclercq, Marie-Paule

    2014-11-28

    Saponins, amphiphiles of natural origin with numerous biological activities, are widely used in the cosmetic and pharmaceutical industry. Some saponins exhibit relatively selective cytotoxic effects on cancer cells but the tendency of saponins to induce hemolysis limits their anticancer potential. This review focused on the effects of saponin activity on membranes and consequent implications for red blood and cancer cells. This activity seems to be strongly related to the amphiphilic character of saponins that gives them the ability to self-aggregate and interact with membrane components such as cholesterol and phospholipids. Membrane interactions of saponins with artificial membrane models, red blood and cancer cells are reviewed with respect to their molecular structures. The review considered the mechanisms of these membrane interactions and their consequences including the modulation of membrane dynamics, interaction with membrane rafts, and membrane lysis. We summarized current knowledge concerning the mechanisms involved in the interactions of saponins with membrane lipids and examined the structure activity relationship of saponins regarding hemolysis and cancer cell death. A critical analysis of these findings speculates on their potential to further develop new anticancer compounds.

  13. Pharmacological targeting of membrane rigidity: implications on cancer cell migration and invasion

    International Nuclear Information System (INIS)

    Braig, Simone; Stoiber, Katharina; Zahler, Stefan; Vollmar, Angelika M

    2015-01-01

    The invasive potential of cancer cells strongly depends on cellular stiffness, a physical quantity that is not only regulated by the mechanical impact of the cytoskeleton but also influenced by the membrane rigidity. To analyze the specific role of membrane rigidity in cancer progression, we treated cancer cells with the Acetyl-CoA carboxylase inhibitor Soraphen A and revealed an alteration of the phospholipidome via mass spectrometry. Migration, invasion, and cell death assays were employed to relate this alteration to functional consequences, and a decrease of migration and invasion without significant impact on cell death has been recorded. Fourier fluctuation analysis of giant plasma membrane vesicles showed that Soraphen A increases membrane rigidity of carcinoma cell membranes. Mechanical measurements of the creep deformation response of whole intact cells were performed using the optical stretcher. The increase in membrane rigidity was observed in one cell line without changing the creep deformation response indicating no restructuring of the cytoskeleton. These data indicate that the increase of membrane rigidity alone is sufficient to inhibit invasiveness of cancer cells, thus disclosing the eminent role of membrane rigidity in migratory processes. (paper)

  14. Correlation between Membrane Potential Responses and Tentacle Movement in the Dinoflagellate Noctiluca miliaris

    OpenAIRE

    Oami, Kazunori

    2004-01-01

    Membrane potential responses and tentacle movement of the marine dinoflagellate Noctiluca miliaris were recorded simultaneously and their time relationships were examined. The food-gathering tentacle of Noctiluca exhibited slow extension-flexion movements in association with the spontaneously recurring membrane potential responses termed the tentacle regulating potentials (TRPs). The flexion of the tentacle began during the slow depolarization of the TRPs. The rate of the flexion increased af...

  15. Correlation between Membrane Potential Responses and Tentacle Movement in the Dinoflagellate Noctiluca miliaris(Behavior Biology)

    OpenAIRE

    Kazunori, Oami; Institute of Biological Sciences, University of Tsukuba

    2004-01-01

    Membrane potential responses and tentacle movement of the marine dinoflagellate Noctiluca miliaris were recorded simultaneously and their time relationships were examined. The food-gathering tentacle of Noctiluca exhibited slow extension-flexion movements in association with the spontaneously recurring membrane potential responses termed the tentacle regulating potentials (TRPs). The flexion of the tentacle began during the slow depolarization of the TRPs. The rate of the flexion increased af...

  16. Lipid modulation of intravascular and cellular sodium handling: mechanistic insights and potential clinical implications.

    Science.gov (United States)

    Amaral, Andre C K B; Sposito, Andrei C

    2006-10-01

    Lipid metabolism can modulate structural and functional characteristics of the vascular system. Recent studies suggested that dyslipidemia may also affect the hemodynamic response to salt intake through the impairment of intravascular volume regulation and cellular sodium handling. Indeed, dyslipidemia may affect sodium homeostasis through several pathways, including defective nitric oxide and eicosanoid production, enhanced renin-angiotensin system activity and increased sympathetic response. Moreover, dyslipidemia directly affects cellular membrane viscosity and modifies membrane ion transport activity. In line with this evidence, attenuation of the above mentioned mechanisms has been demonstrated after lipid-lowering treatment. From the clinical point of view, such interaction between plasma lipids and sodium homeostasis may adversely affect the clinical presentation of diseases such as salt-sensitive hypertension, congestive heart failure, renal diseases with proteinuria or sodium retention. This review considers the interplay between plasma lipids and sodium homeostasis and its potential clinical implication.

  17. Organic fouling behavior of superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membranes functionalized with surface-tailored nanoparticles: Implications for organic fouling in membrane bioreactors

    KAUST Repository

    Liang, Shuai

    2014-08-01

    This study systematically investigates the organic fouling behavior of a superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membrane functionalized via post-fabrication tethering of surface-tailored silica nanoparticles to poly(methacrylic acid)-grafted PVDF membrane surface. Sodium alginate (SA), Suwannee River natural organic matter (SRNOM), and bovine serum albumin (BSA) were used as model organic foulants to investigate the antifouling behavior of the superhydrophilic membrane with combined-fouling (mixture of foulants) and individual-fouling (single foulant) tests. A membrane bioreactor (MBR) plant supernatant was also used to verify the organic antifouling property of the superhydrophilic membrane under realistic conditions. Foulant size distributions and foulant-membrane interfacial forces were measured to interpret the observed membrane fouling behavior. Molecular weight cutoff measurements confirmed that membrane functionalization did not adversely affect the intrinsic membrane selectivity. Both filtration tests with the synthetic foulant-mixture solution (containing SA, SRNOM, and BSA) and MBR plant supernatant demonstrated the reliability and durability of the antifouling property of the superhydrophilic membrane. The conspicuous reduction in foulant-membrane interfacial forces for the functionalized membrane further verified the antifouling properties of the superhydrophilic membrane, suggesting great potential for applications in wastewater treatment. © 2014 Elsevier B.V.

  18. Incidence of Bacteria with Potential Public Health Implications in ...

    African Journals Online (AJOL)

    Lycopersicon esculentum (tomato) is a fleshy berry that is highly perishable and prone to microbial spoilage. The presence of some microorganisms of public health significance makes it a potential health hazard to consumers. There is therefore the need to determine the food safety and public health implications of some of ...

  19. Ion Permeability of Artificial Membranes Evaluated by Diffusion Potential and Electrical Resistance Measurements

    Science.gov (United States)

    Shlyonsky, Vadim

    2013-01-01

    In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and "n"-decane. The electrical resistance and potential…

  20. Intrinsic potential of cell membranes: opposite effects of lipid transmembrane asymmetry and asymmetric salt ion distribution

    DEFF Research Database (Denmark)

    Gurtovenko, Andrey A; Vattulainen, Ilpo

    2009-01-01

    Using atomic-scale molecular dynamics simulations, we consider the intrinsic cell membrane potential that is found to originate from a subtle interplay between lipid transmembrane asymmetry and the asymmetric distribution of monovalent salt ions on the two sides of the cell membrane. It turns out...

  1. Parameter estimation in neuronal stochastic differential equation models from intracellular recordings of membrane potentials in single neurons

    DEFF Research Database (Denmark)

    Ditlevsen, Susanne; Samson, Adeline

    2016-01-01

    Dynamics of the membrane potential in a single neuron can be studied by estimating biophysical parameters from intracellular recordings. Diffusion processes, given as continuous solutions to stochastic differential equations, are widely applied as models for the neuronal membrane potential evolut...

  2. Positive zeta potential of a negatively charged semi-permeable plasma membrane

    Science.gov (United States)

    Sinha, Shayandev; Jing, Haoyuan; Das, Siddhartha

    2017-08-01

    The negative charge of the plasma membrane (PM) severely affects the nature of moieties that may enter or leave the cells and controls a large number of ion-interaction-mediated intracellular and extracellular events. In this letter, we report our discovery of a most fascinating scenario, where one interface (e.g., membrane-cytosol interface) of the negatively charged PM shows a positive surface (or ζ) potential, while the other interface (e.g., membrane-electrolyte interface) still shows a negative ζ potential. Therefore, we encounter a completely unexpected situation where an interface (e.g., membrane-cytosol interface) that has a negative surface charge density demonstrates a positive ζ potential. We establish that the attainment of such a property by the membrane can be ascribed to an interplay of the nature of the membrane semi-permeability and the electrostatics of the electric double layer established on either side of the charged membrane. We anticipate that such a membrane property can lead to such capabilities of the cell (in terms of accepting or releasing certain kinds of moieties as well regulating cellular signaling) that was hitherto inconceivable.

  3. Influence of Glucose Deprivation on Membrane Potentials of Plasma Membranes, Mitochondria and Synaptic Vesicles in Rat Brain Synaptosomes.

    Science.gov (United States)

    Hrynevich, Sviatlana V; Pekun, Tatyana G; Waseem, Tatyana V; Fedorovich, Sergei V

    2015-06-01

    Hypoglycemia can cause neuronal cell death similar to that of glutamate-induced cell death. In the present paper, we investigated the effect of glucose removal from incubation medium on changes of mitochondrial and plasma membrane potentials in rat brain synaptosomes using the fluorescent dyes DiSC3(5) and JC-1. We also monitored pH gradients in synaptic vesicles and their recycling by the fluorescent dye acridine orange. Glucose deprivation was found to cause an inhibition of K(+)-induced Ca(2+)-dependent exocytosis and a shift of mitochondrial and plasma membrane potentials to more positive values. The sensitivity of these parameters to the energy deficit caused by the removal of glucose showed the following order: mitochondrial membrane potential > plasma membrane potential > pH gradient in synaptic vesicles. The latter was almost unaffected by deprivation compared with the control. The pH-dependent dye acridine orange was used to investigate synaptic vesicle recycling. However, the compound's fluorescence was shown to be enhanced also by the mixture of mitochondrial toxins rotenone (10 µM) and oligomycin (5 µg/mL). This means that acridine orange can presumably be partially distributed in the intermembrane space of mitochondria. Glucose removal from the incubation medium resulted in a 3.7-fold raise of acridine orange response to rotenone + oligomycin suggesting a dramatic increase in the mitochondrial pH gradient. Our results suggest that the biophysical characteristics of neuronal presynaptic endings do not favor excessive non-controlled neurotransmitter release in case of hypoglycemia. The inhibition of exocytosis and the increase of the mitochondrial pH gradient, while preserving the vesicular pH gradient, are proposed as compensatory mechanisms.

  4. Influence of membrane potential on conductance sublevels of chloride channels activated by GABA.

    Science.gov (United States)

    Gage, P W; Chung, S H

    1994-02-22

    Single-channel chloride currents activated by 0.5 microM GABA were recorded in cell-attached and inside-out membrane patches from rat cultured hippocampal neurons. The currents displayed multiple conductance states and outward rectification. The number and amplitude of conductance levels were determined over a range of potentials by using digital signal-processing techniques. It was found that, except for a level close to zero, subconductance levels were regularly spaced. There were fewer sublevels at hyperpolarized than at depolarized potentials, and the spacing between levels varied linearly with potential giving an incremental conductance of 8-10 pS that was independent of membrane potential. Outward rectification is related to the change in the number of conductance levels with potential. One hypothesis that is consistent with these observations is that a channel is composed of a number of synchronized, non-rectifying, conducting pores, and that the number of pores activated changes with membrane potential.

  5. Induced-Charge Enhancement of the Diffusion Potential in Membranes with Polarizable Nanopores.

    Science.gov (United States)

    Ryzhkov, I I; Lebedev, D V; Solodovnichenko, V S; Shiverskiy, A V; Simunin, M M

    2017-12-01

    When a charged membrane separates two salt solutions of different concentrations, a potential difference appears due to interfacial Donnan equilibrium and the diffusion junction. Here, we report a new mechanism for the generation of a membrane potential in polarizable conductive membranes via an induced surface charge. It results from an electric field generated by the diffusion of ions with different mobilities. For uncharged membranes, this effect strongly enhances the diffusion potential and makes it highly sensitive to the ion mobilities ratio, electrolyte concentration, and pore size. Theoretical predictions on the basis of the space-charge model extended to polarizable nanopores fully agree with experimental measurements in KCl and NaCl aqueous solutions.

  6. Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements.

    Science.gov (United States)

    Shlyonsky, Vadim

    2013-12-01

    In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and n-decane. The electrical resistance and potential difference across these membranes can be easily measured using a low-cost volt-ohm meter and home-made Ag/AgCl electrodes. The advantage of the model is the lack of ionic selectivity of the membrane, which can be modified by the introduction of different ionophores to the organic liquid mixture. A membrane treated with the mixture containing valinomycin generates voltages from -53 to -25 mV in the presence of a 10-fold KCl gradient (in to out) and from -79 to -53 mV in the presence of a bi-ionic KCl/NaCl gradient (in to out). This latter bi-ionic gradient potential reverses to a value from +9 to +20 mV when monensin is present in the organic liquid mixture. Thus, the model can be build stepwise, i.e., all factors leading to the development of diffusion potentials can be introduced sequentially, helping students to understand the quantitative relationships of ionic gradients and differential membrane permeability in the generation of cell electrical signals.

  7. Influence of Active Layer on Separation Potentials of Nanofiltration Membranes for Inorganic Ions.

    Science.gov (United States)

    Wadekar, Shardul S; Vidic, Radisav D

    2017-05-16

    Active layers of two fully aromatic and two semi-aromatic nanofiltration membranes were studied along with surface charge at different electrolyte composition and effective pore size to elucidate their influence on separation mechanisms for inorganic ions by steric, charge, and dielectric exclusion. The membrane potential method used for pore size measurement is underlined as the most appropriate measurement technique for this application owing to its dependence on the diffusional potentials of inorganic ions. Crossflow rejection experiments with dilute feed composition indicate that both fully aromatic membranes achieved similar rejection despite the differences in surface charge, which suggests that rejection by these membranes is exclusively dependent on size exclusion and the contribution of charge exclusion is weak. Rejection experiments with higher ionic strength and different composition of the feed solution confirmed this hypothesis. On the other hand, increase in the ionic strength of feed solution when the charge exclusion effects are negligible due to charge screening strongly influenced ion rejection by semi-aromatic membranes. The experimental results confirmed that charge exclusion contributes significantly to the performance of semi-aromatic membranes in addition to size exclusion. The contribution of dielectric exclusion to overall ion rejection would be more significant for fully aromatic membranes.

  8. Amnion and Chorion Membranes: Potential Stem Cell Reservoir with Wide Applications in Periodontics

    Directory of Open Access Journals (Sweden)

    Akanksha Gupta

    2015-01-01

    Full Text Available The periodontal therapy usually aims at elimination of disease causing bacteria and resolution of inflammation. It involves either resective or regenerative surgery to resolve the inflammation associated defects. Over the years, several methods have been used for achievement of periodontal regeneration. One of the oldest biomaterials used for scaffolds is the fetal membrane. The amniotic membranes of developing embryo, that is, amnion (innermost lining and chorion (a layer next to it, have the properties with significant potential uses in dentistry. This paper reviews the properties, mechanism of action, and various applications of these placental membranes in general and specifically in Periodontics.

  9. Hamster oocyte membrane potential and ion permeability vary with preantral cumulus cell attachment and developmental stage

    Directory of Open Access Journals (Sweden)

    Miller Raymond L

    2001-10-01

    Full Text Available Abstract Background In vitro maturation of mammalian oocytes is an area of great interest due to its potential application in the treatment of infertility. The morphological and physiological changes that occur during oocyte development are poorly understood, and further studies are needed investigating the physiological changes associated with oocyte maturation. In this study we evaluated the membrane potential and the sodium/potassium permeability ratio of oocytes acutely isolated, and cumulus-oocyte complexes in metaphase II and preantral follicle stages. Results Intracellular electrical recordings revealed that cumulus-enclosed oocytes have a membrane potential significantly more negative at the preantral follicle stage than at metaphase II stage (-38.4 versus -19.7 mV, p Conclusions These data show a change in the membrane potential and Na+/K+ permeability ratio during ooycte development from the preantral stage oocyte to the metaphase II stage. We have also demonstrated a change in the preantral oocyte membrane potential when surrounding cumulus cells are removed; either due to membrane changes or loss of cumulus cells.

  10. Energy-producing system of the membrane potential generation in γ-irradiated Streptococcus faecalis

    International Nuclear Information System (INIS)

    Fomenko, B.S.

    1976-01-01

    γ-irradiated (20-100 krads) Str. faecalis cells exhibited increased glycolytic and ATPase activity whereas the ATP level remained unaffected by radiation. It is concluded that the radiation-induced reduction of the membrane potential in Str. faecalis, that has been earlier described, is not connected with the impairment of the energy-producing system of the potential generation

  11. Membrane-Mediated Oligomerization of G Protein Coupled Receptors and Its Implications for GPCR Function.

    Science.gov (United States)

    Gahbauer, Stefan; Böckmann, Rainer A

    2016-01-01

    The dimerization or even oligomerization of G protein coupled receptors (GPCRs) causes ongoing, controversial debates about its functional role and the coupled biophysical, biochemical or biomedical implications. A continously growing number of studies hints to a relation between oligomerization and function of GPCRs and strengthens the assumption that receptor assembly plays a key role in the regulation of protein function. Additionally, progress in the structural analysis of GPCR-G protein and GPCR-ligand interactions allows to distinguish between actively functional and non-signaling complexes. Recent findings further suggest that the surrounding membrane, i.e., its lipid composition may modulate the preferred dimerization interface and as a result the abundance of distinct dimeric conformations. In this review, the association of GPCRs and the role of the membrane in oligomerization will be discussed. An overview of the different reported oligomeric interfaces is provided and their capability for signaling discussed. The currently available data is summarized with regard to the formation of GPCR oligomers, their structures and dependency on the membrane microenvironment as well as the coupling of oligomerization to receptor function.

  12. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...

  13. Demineralized Freeze-Dried Bovine Cortical Bone: Its Potential for Guided Bone Regeneration Membrane

    Directory of Open Access Journals (Sweden)

    David B. Kamadjaja

    2017-01-01

    Full Text Available Background. Bovine pericardium collagen membrane (BPCM had been widely used in guided bone regeneration (GBR whose manufacturing process usually required chemical cross-linking to prolong its biodegradation. However, cross-linking of collagen fibrils was associated with poorer tissue integration and delayed vascular invasion. Objective. This study evaluated the potential of bovine cortical bone collagen membrane for GBR by evaluating its antigenicity potential, cytotoxicity, immune and tissue response, and biodegradation behaviors. Material and Methods. Antigenicity potential of demineralized freeze-dried bovine cortical bone membrane (DFDBCBM was done with histology-based anticellularity evaluation, while cytotoxicity was analyzed using MTT Assay. Evaluation of immune response, tissue response, and biodegradation was done by randomly implanting DFDBCBM and BPCM in rat’s subcutaneous dorsum. Samples were collected at 2, 5, and 7 days and 7, 14, 21, and 28 days for biocompatibility and tissue response-biodegradation study, respectively. Result. DFDBCBM, histologically, showed no retained cells; however, it showed some level of in vitro cytotoxicity. In vivo study exhibited increased immune response to DFDBCBM in early healing phase; however, normal tissue response and degradation rate were observed up to 4 weeks after DFDBCBM implantation. Conclusion. Demineralized freeze-dried bovine cortical bone membrane showed potential for clinical application; however, it needs to be optimized in its biocompatibility to fulfill all requirements for GBR membrane.

  14. TCA Cycle and Mitochondrial Membrane Potential Are Necessary for Diverse Biological Functions.

    Science.gov (United States)

    Martínez-Reyes, Inmaculada; Diebold, Lauren P; Kong, Hyewon; Schieber, Michael; Huang, He; Hensley, Christopher T; Mehta, Manan M; Wang, Tianyuan; Santos, Janine H; Woychik, Richard; Dufour, Eric; Spelbrink, Johannes N; Weinberg, Samuel E; Zhao, Yingming; DeBerardinis, Ralph J; Chandel, Navdeep S

    2016-01-21

    Mitochondrial metabolism is necessary for the maintenance of oxidative TCA cycle function and mitochondrial membrane potential. Previous attempts to decipher whether mitochondria are necessary for biological outcomes have been hampered by genetic and pharmacologic methods that simultaneously disrupt multiple functions linked to mitochondrial metabolism. Here, we report that inducible depletion of mitochondrial DNA (ρ(ο) cells) diminished respiration, oxidative TCA cycle function, and the mitochondrial membrane potential, resulting in diminished cell proliferation, hypoxic activation of HIF-1, and specific histone acetylation marks. Genetic reconstitution only of the oxidative TCA cycle function specifically in these inducible ρ(ο) cells restored metabolites, resulting in re-establishment of histone acetylation. In contrast, genetic reconstitution of the mitochondrial membrane potential restored ROS, which were necessary for hypoxic activation of HIF-1 and cell proliferation. These results indicate that distinct mitochondrial functions associated with respiration are necessary for cell proliferation, epigenetics, and HIF-1 activation. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Fundamental transport mechanisms, fabrication and potential applications of nanoporous atomically thin membranes

    Science.gov (United States)

    Wang, Luda; Boutilier, Michael S. H.; Kidambi, Piran R.; Jang, Doojoon; Hadjiconstantinou, Nicolas G.; Karnik, Rohit

    2017-06-01

    Graphene and other two-dimensional materials offer a new approach to controlling mass transport at the nanoscale. These materials can sustain nanoscale pores in their rigid lattices and due to their minimum possible material thickness, high mechanical strength and chemical robustness, they could be used to address persistent challenges in membrane separations. Here we discuss theoretical and experimental developments in the emerging field of nanoporous atomically thin membranes, focusing on the fundamental mechanisms of gas- and liquid-phase transport, membrane fabrication techniques and advances towards practical application. We highlight potential functional characteristics of the membranes and discuss applications where they are expected to offer advantages. Finally, we outline the major scientific questions and technological challenges that need to be addressed to bridge the gap from theoretical simulations and proof-of-concept experiments to real-world applications.

  16. Relationship between presynaptic membrane potential and acetylcholine release in synaptosomes from Torpedo electric organ.

    Science.gov (United States)

    Meunier, F M

    1984-01-01

    The membrane potential of purely cholinergic synaptosomes isolated from Torpedo electric organ was monitored with fluorescent carbocyanine dyes. An increased fluorescence was associated with depolarization and a quenching with hyperpolarization. Fluorescence data provided evidence that Torpedo synaptosomes have a membrane potential mainly driven by a K+ diffusion potential and a membrane potential of about -50 mV could be estimated after calibration of fluorescence signals with ionophore antibiotics. The release of acetylcholine (ACh) from Torpedo synaptosomes was monitored continuously by measuring the light emitted by a chemiluminescent method (Israël & Lesbats, 1981 a). Using fluorescence data, the release of ACh was expressed as a function of membrane potential. The relationship between presynaptic potential and transmitter release as determined by biochemical methods at cholinergic nerve endings showed striking similarities to that observed at the squid giant synapse. Several substances were also tested with regard to their depolarizing and releasing properties and it was found that the toxin isolated from the venom of the annelid Glycera convoluta, which induced a large increase in quantal release of transmitter (Manaranche, Thieffry, & Israël, 1980) promoted a depolarization of Torpedo synaptosomes in addition to ACh release. PMID:6207289

  17. Development of a no-wash assay for mitochondrial membrane potential using the styryl dye DASPEI

    DEFF Research Database (Denmark)

    Reveles Jensen, Kristian; Rekling, Jens C

    2010-01-01

    in CHO cells exposed to cobalt (mimicking hypoxia) and in PC12 cells exposed to amyloid ß, demonstrating that the assay can be used in cellular models of hypoxia and Alzheimer's disease. The assay needs no washing steps, has a Z' value >0.5, can be used on standard fluorometers, has good post liquid......, which is a suspected mitochondrial toxicant. CCCP and DNP have short-term depolarizing effects, and thioridazine has long-term hyperpolarizing effects on the mitochondrial membrane potential of Chinese hamster ovary (CHO) cells. The assay also detected changes of the mitochondrial membrane potential...

  18. Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential.

    Science.gov (United States)

    Loubet, Bastien; Lomholt, Michael Andersen; Khandelia, Himanshu

    2013-10-28

    We investigate the effect of an applied electric potential on the mechanics of a coarse grained POPC bilayer under tension. The size and duration of our simulations allow for a detailed and accurate study of the fluctuations. Effects on the fluctuation spectrum, tension, bending rigidity, and bilayer thickness are investigated in detail. In particular, the least square fitting technique is used to calculate the fluctuation spectra. The simulations confirm a recently proposed theory that the effect of an applied electric potential on the membrane will be moderated by the elastic properties of the membrane. In agreement with the theory, we find that the larger the initial tension the larger the effect of the electric potential. Application of the electric potential increases the amplitude of the long wavelength part of the spectrum and the bending rigidity is deduced from the short wavelength fluctuations. The effect of the applied electric potential on the bending rigidity is non-existent within error bars. However, when the membrane is stretched there is a point where the bending rigidity is lowered due to a decrease of the thickness of the membrane. All these effects should prove important for mechanosensitive channels and biomembrane mechanics in general.

  19. TTX-Resistant NMDA Receptor-Mediated Membrane Potential Oscillations in Neonatal Mouse Hb9 Interneurons

    Science.gov (United States)

    Masino, Mark A.; Abbinanti, Matthew D.; Eian, John; Harris-Warrick, Ronald M.

    2012-01-01

    Conditional neuronal membrane potential oscillations have been identified as a potential mechanism to help support or generate rhythmogenesis in neural circuits. A genetically identified population of ventromedial interneurons, called Hb9, in the mouse spinal cord has been shown to generate TTX-resistant membrane potential oscillations in the presence of NMDA, serotonin and dopamine, but these oscillatory properties are not well characterized. Hb9 interneurons are rhythmically active during fictive locomotor-like behavior. In this study, we report that exogenous N-Methyl-D-Aspartic acid (NMDA) application is sufficient to produce membrane potential oscillations in Hb9 interneurons. In contrast, exogenous serotonin and dopamine application, alone or in combination, are not sufficient. The properties of NMDA-induced oscillations vary among the Hb9 interneuron population; their frequency and amplitude increase with increasing NMDA concentration. NMDA does not modulate the T-type calcium current (ICa(T)), which is thought to be important in generating locomotor-like activity, in Hb9 neurons. These results suggest that NMDA receptor activation is sufficient for the generation of TTX-resistant NMDA-induced membrane potential oscillations in Hb9 interneurons. PMID:23094101

  20. What Can We Learn about Cholesterol's Transmembrane Distribution Based on Cholesterol-Induced Changes in Membrane Dipole Potential?

    Czech Academy of Sciences Publication Activity Database

    Falkovich, S. G.; Martinez-Seara, Hector; Nesterenko, A. M.; Vattulainen, I.; Gurtovenko, A. A.

    2016-01-01

    Roč. 7, č. 22 (2016), s. 4585-4590 ISSN 1948-7185 Institutional support: RVO:61388963 Keywords : membrane * cholesterol * membrane asymmetry * membrane dipole potential * transmembrane distribution Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.353, year: 2016

  1. Membrane distillation for wastewater reverse osmosis concentrate treatment with water reuse potential

    KAUST Repository

    Naidu, Gayathri

    2016-11-29

    Membrane distillation (MD) was evaluated as a treatment option of wastewater reverse osmosis concentrate (WWROC) discharged from wastewater reclamation plants (WRPs). A direct contact MD (DCMD), at obtaining 85% water recovery of WWROC showed only 13–15% flux decline and produced good quality permeate (10–15 µS/cm, 99% ion rejection) at moderate feed temperature of 55 °C. Prevalent calcium carbonate (CaCO3) deposition on the MD membrane occurred in treating WWROC at elevated concentrations. The combination of low salinity and loose CaCO3 adhesion on the membrane did not significantly contribute to DCMD flux decline. Meanwhile, high organic content in WWROC (58–60 mg/L) resulted in a significant membrane hydrophobicity reduction (70% lower water contact angle than virgin membrane) attributed to low molecular weight organic adhesion onto the MD membrane. Granular activated carbon (GAC) pretreatment helped in reducing organic contents of WWROC by 46–50%, and adsorbed a range of hydrophobic and hydrophilic micropollutants. This ensured high quality water production by MD (micropollutants-free) and enhanced its reuse potential. The MD concentrated WWROC was suitable for selective ion precipitation, promising a near zero liquid discharge in WRPs.

  2. Insertion of Neurotransmitters into a Lipid Bilayer Membrane and Its Implication on Membrane Stability: A Molecular Dynamics Study.

    Science.gov (United States)

    Shen, Chun; Xue, Minmin; Qiu, Hu; Guo, Wanlin

    2017-03-17

    The signaling molecules in neurons, called neurotransmitters, play an essential role in the transportation of neural signals, during which the neurotransmitters interact with not only specific receptors, but also cytomembranes, such as synaptic vesicle membranes and postsynaptic membranes. Through extensive molecular dynamics simulations, the atomic-scale insertion dynamics of typical neurotransmitters, including methionine enkephalin (ME), leucine enkephalin (LE), dopamine (DA), acetylcholine (ACh), and aspartic acid (ASP), into lipid bilayers is investigated. The results show that the first three neurotransmitters (ME, LE, and DA) are able to diffuse freely into both 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) membranes, and are guided by the aromatic residues Tyr and Phe. Only a limited number of these neurotransmitters are allowed to penetrate into the membrane, which suggests an intrinsic mechanism by which the membrane is protected from being destroyed by excessive inserted neurotransmitters. After spontaneous insertion, the neurotransmitters disturb the surrounding phospholipids in the membrane, as indicated by the altered distribution of components in lipid leaflets and the disordered lipid tails. In contrast, the last two neurotransmitters (ACh and ASP) cannot enter the membrane, but instead always diffuse freely in solution. These findings provide an understanding at the atomic level of how neurotransmitters interact with the surrounding cytomembrane, as well as their impact on membrane behavior. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Evaluation of the potential anti-adhesion effect of the PVA/Gelatin membrane.

    Science.gov (United States)

    Bae, Sang-Ho; Son, So-Ra; Kumar Sakar, Swapan; Nguyen, Thi-Hiep; Kim, Shin-Woo; Min, Young-Ki; Lee, Byong-Taek

    2014-05-01

    A common and prevailing complication for patients with abdominal surgery is the peritoneal adhesion that follows during the post-operative recovery period. Biodegradable polymers have been suggested as a barrier to prevent the peritoneal adhesion. In this work, as a preventive method, PVA/Gelatin hydrogel-based membrane was investigated with various combinations of PVA and gelatin (50/50, 30/70/, and 10/90). Membranes were made by casting method using hot PVA-gelatin solution and the gelatin was cross-linked by exposing UV irradiation for 5 days to render stability of the produced sheathed form in the physiological environment. Physical crosslinking was chosen to avoid the problems of potential cytotoxic effect of chemical crosslinking. Their materials characterization and mechanical properties were evaluated by SEM surface characterization, hydrophilicity, biodegradation rate, and so forth. Cytocompatibility was observed by in vitro experiments with cell proliferation using confocal laser scanning microscopy and the MTT assay by L-929 mouse fibroblast cells. The fabricated PVA/Gel membranes were implanted between artificially defected cecum and peritoneal wall in rats and were sacrificed after 1 and 2 weeks post-operative to compare their tissue adhesion extents with that of control group where the defected surface was not separated by PVA/Gel membrane. The PVA/Gel membrane (10/90) significantly reduced the adhesion extent and showed to be a potential candidate for the anti-adhesion application. Copyright © 2013 Wiley Periodicals, Inc.

  4. Bcl-xL regulates mitochondrial energetics by stabilizing the inner membrane potential.

    Science.gov (United States)

    Chen, Ying-Bei; Aon, Miguel A; Hsu, Yi-Te; Soane, Lucian; Teng, Xinchen; McCaffery, J Michael; Cheng, Wen-Chih; Qi, Bing; Li, Hongmei; Alavian, Kambiz N; Dayhoff-Brannigan, Margaret; Zou, Shifa; Pineda, Fernando J; O'Rourke, Brian; Ko, Young H; Pedersen, Peter L; Kaczmarek, Leonard K; Jonas, Elizabeth A; Hardwick, J Marie

    2011-10-17

    Mammalian Bcl-x(L) protein localizes to the outer mitochondrial membrane, where it inhibits apoptosis by binding Bax and inhibiting Bax-induced outer membrane permeabilization. Contrary to expectation, we found by electron microscopy and biochemical approaches that endogenous Bcl-x(L) also localized to inner mitochondrial cristae. Two-photon microscopy of cultured neurons revealed large fluctuations in inner mitochondrial membrane potential when Bcl-x(L) was genetically deleted or pharmacologically inhibited, indicating increased total ion flux into and out of mitochondria. Computational, biochemical, and genetic evidence indicated that Bcl-x(L) reduces futile ion flux across the inner mitochondrial membrane to prevent a wasteful drain on cellular resources, thereby preventing an energetic crisis during stress. Given that F(1)F(O)-ATP synthase directly affects mitochondrial membrane potential and having identified the mitochondrial ATP synthase β subunit in a screen for Bcl-x(L)-binding partners, we tested and found that Bcl-x(L) failed to protect β subunit-deficient yeast. Thus, by bolstering mitochondrial energetic capacity, Bcl-x(L) may contribute importantly to cell survival independently of other Bcl-2 family proteins.

  5. Concentration of field and skim latex by microfiltration - membrane fouling and biochemical methane potential of serum.

    Science.gov (United States)

    Thongmak, Narumol; Sridang, Porntip; Puetpaiboon, Udomphon; Grasmick, Alain

    2015-01-01

    Cross-flow microfiltration was used to concentrate field and skim latex suspensions and recover the smallest compounds (proteins, sugars, etc.) in permeate (serum solutions). The experiments were performed in a lab-scale microfiltration unit equipped with ceramic membranes. In continuous mode, the operations were performed at constant trans-membrane pressure (0.5 bars), constant cross-flow velocity (3 m/s) and constant temperature (28 ± 2°C). In retentate, the volumetric concentration factor was only close to 2 (about 54% of total solid content, TSC) when concentrating the field latex suspensions, and it reached 10 (close to 40% TSC) when concentrating skim latex suspensions. The quality of retentate suspensions let envisage a significant potential of industrial valorization. The membrane fouling rates appeared as an increasing function of dry rubber content suspension, and the main fouling origin (94%) was linked to a reversible accumulation of suspended compounds on the membrane surface. Permeate appeared as a clear yellow solution containing the smallest soluble organic fractions that show a high degree of biodegradability when using biochemical methane potential tests. The chemical oxygen demand (COD) removal was then higher than 92% and the methane production yield was close to 0.29 NLCH4/gCODremoved. The association of a membrane separation step and anaerobic digestion appeared, then, as a relevant solution to recover rubber content from skim latex suspensions and energy from the anaerobic digestion of serum.

  6. Evaluation of the Standard Ion Transfer Potentials for PVC Plasticized Membranes from Voltammetric Measurements

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Stejskalová, Květoslava; Samec, Zdeněk

    2001-01-01

    Roč. 496, č. 1 (2001), s. 143-147 ISSN 0022-0728. [Symposium in Kyoto. Kyoto, 02.03.2000] R&D Projects: GA AV ČR IAA4040902 Institutional research plan: CEZ:AV0Z4040901 Keywords : ion voltammetry * PVC plasticized membrane * standard ion transfer potential Subject RIV: CG - Electrochemistry Impact factor: 1.960, year: 2001

  7. Effect of membrane potential on dialysis of calcium in a continuous-flow system.

    Science.gov (United States)

    Staley, M J; Farrance, I

    1978-12-01

    Electical potentials across the membrane in a modified AutoAnalyzer dialyzer (Technicon) have been determined under various conditions and related to the dialysis of 45Ca. The results suggest that anomalies in the diffusion of calcium from protein and nonprotein containing streams could be due to factors other than "Donnan equilibrium effects."

  8. Streaming potential investigations of polymer membranes developed for direct methanol fuel cell application

    Czech Academy of Sciences Publication Activity Database

    Richau, K.; Mohr, R.; Kůdela, Vlastimil; Schauer, Jan

    2003-01-01

    Roč. 14, - (2003), s. 201-204 ISSN 0915-860X. [International Conference on Ion Exchange. Kanazawa, 14.07.2003-18.07.2003] R&D Projects: GA MŠk ME 366 Institutional research plan: CEZ:AV0Z4050913 Keywords : streaming potential * ion-exchange membranes * specific conductivity Subject RIV: CG - Electrochemistry

  9. Involvement of membrane potential in alkaline band formation by internodal cells of Chara corallina.

    Science.gov (United States)

    Shimmen, Teruo; Wakabayashi, Akiko

    2008-10-01

    Internodal cells of Chara corallina form alkaline bands on their surface upon illumination via photosynthesis. In the present study, the effect of KCl on alkaline band formation was analyzed. When the extracellular KCl concentration was increased, alkaline band formation was extensively inhibited. Electrophysiological analysis unequivocally showed the need for inner negative membrane potential for alkaline band formation.

  10. Spike-threshold adaptation predicted by membrane potential dynamics in vivo.

    Directory of Open Access Journals (Sweden)

    Bertrand Fontaine

    2014-04-01

    Full Text Available Neurons encode information in sequences of spikes, which are triggered when their membrane potential crosses a threshold. In vivo, the spiking threshold displays large variability suggesting that threshold dynamics have a profound influence on how the combined input of a neuron is encoded in the spiking. Threshold variability could be explained by adaptation to the membrane potential. However, it could also be the case that most threshold variability reflects noise and processes other than threshold adaptation. Here, we investigated threshold variation in auditory neurons responses recorded in vivo in barn owls. We found that spike threshold is quantitatively predicted by a model in which the threshold adapts, tracking the membrane potential at a short timescale. As a result, in these neurons, slow voltage fluctuations do not contribute to spiking because they are filtered by threshold adaptation. More importantly, these neurons can only respond to input spikes arriving together on a millisecond timescale. These results demonstrate that fast adaptation to the membrane potential captures spike threshold variability in vivo.

  11. Multiple paths towards reduced membrane potential and concomitant reduction in aminoglycoside susceptibility in staphylococcus aureus

    DEFF Research Database (Denmark)

    Vestergaard, Martin; Nøhr-Meldgaard, Katrine; Ingmer, Hanne

    2018-01-01

    the largest increase in gentamicin susceptibility and exhibited a small colony variant phenotype, whereas the remaining mutants (qoxA, qoxB, qoxC, ndh and hemX) displayed colony morphology similar to the wild type. All of the mutants, except hemX, displayed reduced membrane potential suggesting that reduced...

  12. Membrane potential, serum calcium and serum selenium decrease in preeclampsia subjects in Owerri

    Directory of Open Access Journals (Sweden)

    Johnkennedy Nnodim

    2017-08-01

    Full Text Available Background Pre-eclampsia is a serious hypertensive condition of pregnancy associated with high maternal and fetal morbidity and mortality. Women who have had pre-eclampsia have a greater risk of developing hypertension, stroke and ischemic heart disease in later life. The etiology of pre-eclampsia remains unclear. Placental insufficiency plays a key role in the progression of this disease. The aim of this study was to determine membrane potential, serum calcium and serum selenium levels in preeclampsia subjects in Owerri.   Methods A case control study involving 200 primigravida (100 preeclamptic and 100 apparently healthy between the ages of 20 and 32 years attending General Hospital Owerri. Fasting venous blood was collected for the determination of serum selenium and serum calcium while membrane potential was calculated using the Nernst equation. The serum calcium was estimated using Randox Kit and serum selenium by atomic absorption spectrophotometry. The Independent Student t test was used for statistical analysis.   Results The results revealed that membrane potential and serum selenium as well as serum calcium were significantly decreased in preeclampsia when compared with the controls, at p<0.05.   Conclusion Our study demonstrated that the decrease in membrane potential, serum calcium and serum selenium levels may play a critical role in the pathogenesis of pre-eclampsia. There may be a need for increasing the dietary intake of these essential trace metals during pregnancy to prevent pre-eclampsia in Owerri.

  13. Orientation effects on bipolar and other asymmetric membranes as observed by concentration potentials

    Czech Academy of Sciences Publication Activity Database

    Kůdela, Vlastimil; Richau, K.; Bleha, Miroslav; Paul, D.

    22-23, - (2001), s. 655-662 ISSN 1383-5866 R&D Projects: GA MŠk ME 079; GA AV ČR KSK2050602 Institutional research plan: CEZ:AV0Z4050913 Keywords : asymmetric membranes * concentration potentials * orientation effects Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.552, year: 2001

  14. [Modelling of pattern formation and oscillations in pH and transmembrane potential near the cell membrane of Chara corallina].

    Science.gov (United States)

    Pliusnina, T Iu; Lavrova, A I; Riznichenko, G Iu; Rubin, A B

    2005-01-01

    A mathematical model of potencial-dependent proton transfer across the membrane of Chara corallina cells is considered. To construct the model, partial differential equations describing the system dynamics in time and in space were used. The variables of the model are the proton concentration and membrane potential. The model describes the experimentally observed inhomogeneous distribution of transmembrane potential and pH along the membrane and oscillations of the potential and pH in time. A mechanism of the distribution of pH and membrane potential along the Chara corallina cell is suggested.

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

    Directory of Open Access Journals (Sweden)

    Seong-Woon Yu

    2009-10-01

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

  16. Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

    DEFF Research Database (Denmark)

    Loubet, Bastien; Lomholt, Michael Andersen; Khandelia, Himanshu

    2013-01-01

    We investigate the effect of an applied electric potential on the mechanics of a coarse grained POPC bilayer under tension. The size and duration of our simulations allow for a detailed and accurate study of the fluctuations. Effects on the fluctuation spectrum, tension, bending rigidity......, and bilayer thickness are investigated in detail. In particular, the least square fitting technique is used to calculate the fluctuation spectra. The simulations confirm a recently proposed theory that the effect of an applied electric potential on the membrane will be moderated by the elastic properties...... of the membrane. In agreement with the theory, we find that the larger the initial tension the larger the effect of the electric potential. Application of the electric potential increases the amplitude of the long wavelength part of the spectrum and the bending rigidity is deduced from the short wavelength...

  17. [HOMOCYSTEINE-INDUCED MEMBRANE CURRENTS, CALCIUM RESPONSES AND CHANGES OF MITOCHONDRIAL POTENTIAL IN RAT CORTICAL NEURONS].

    Science.gov (United States)

    Abushik, P A; Karelina, T V; Sibarov, D A; Stepanenko, J D; Giniatullin, R; Antonov, S M

    2015-01-01

    Homocysteine, a sulfur-containing amino acid, exhibits neurotoxic effects and is involved in the pathogenesis of several major neurodegenerative disorders. In contrast to well studied excitoxicity of glutamate, the mechanism of homocysteine neurotoxicity is not clearly understood. By using whole-cell patch-clamp, calcium imaging (fluo-3) and measurements of mitochondrial membrane potential (rhodamine 123) we studied transmembrane currents, calcium signals and changes in mitochondrial membrane potential induced by homocysteine versus responses induced by NMDA and glutamate in cultured rat cortical neurons. L-homocysteine (50 µM) induced inward currents that could be completely blocked by the selective antagonist of NMDA receptors - AP-5. In contrast to NMDA-induced currents, homocysteine-induced currents had a smaller steady-state amplitude. Comparison of calcium responses to homocysteine, NMDA or glutamate demonstrated that in all cortical neurons homocysteine elicited short, oscillatory-type calcium responses, whereas NMDA or glutamate induced sustained increase of intracellular calcium. Analysis of mitochondrial changes demonstrated that in contrast to NMDA homocysteine did not cause a drop of mitochondrial membrane potential at the early stages of action. However, after its long-term action, as in the case of NMDA and glutamate, the changes in mitochondrial membrane potential were comparable with the full drop of respiratory chain induced by protonophore FCCP. Our data suggest that in cultured rat cortical neuron homocysteine at the first stages of action induces neurotoxic effects through activation of NMDA-type ionotropic glutamate receptors with strong calcium influx through the channels of these receptors. The long-term action of homocysteine may lead to mitochondrial disfuction and appears as a drop of mitochondrial membrane potential.

  18. Role of membrane potential on artificial transformation of E. coli with plasmid DNA.

    Science.gov (United States)

    Panja, Subrata; Saha, Swati; Jana, Bimal; Basu, Tarakdas

    2006-12-15

    The standard method of transformation of Escherichea coli with plasmid DNA involves two important steps: cells are first suspended in 100mM CaCl(2) at 0 degrees C (in which DNA is added), followed by the administration of a heat-pulse from 0 to 42 degrees C for 90s [Cohen, S., Chang, A., Hsu, L., 1972. Nonchromosomal antibiotic resistance in bacteria. Proc. Natl. Acad. Sci. U.S.A., 69, 2110-2114]. The first step makes the cells competent for uptake of DNA and the second step is believed to facilitate the DNA entry into the cells by an unknown mechanism. In this study, the measure of membrane potential of the intact competent cells, at different steps of transformation process, either by the method of spectrofluorimetry or that of flow cytometry, indicates that the heat-pulse step (0-->42 degrees C) heavily decreases the membrane potential. A subsequent cold shock (42-->0 degrees C) raises the potential further to its original value. Moreover, the efficiency of transformation of E. coli XL1 Blue cells with plasmid pUC19 DNA remains unaltered when the heat-pulse step is replaced by the incubation of the DNA-adsorbed competent cells with 10 microM carbonyl cyanide m-chlorophenyl hydrazone (CCCP) for 90s at 0 degrees C. Since the CCCP, a well-known protonophore, reduces membrane potential by dissipating the proton-motive-force (PMF) across E. coli plasma membrane, our experimental results suggest that the heat-pulse step of the standard transformation procedure facilitates DNA entry into the cells by lowering the membrane potential.

  19. Infection-Induced Thrombin Production: A Potential Novel Mechanism for Preterm Premature Rupture of Membranes (PPROM).

    Science.gov (United States)

    Feng, Liping; Allen, Terrence K; Marinello, William P; Murtha, Amy P

    2018-04-13

    decidua cells was perinuclear and cytoplasmic. Prothrombin mRNA and protein expression in fetal membranes was significantly increased by U. parvum, but not lipopolysaccharide, treatments in a dose-dependent manner. Specifically, U. parvum at a dose of 1x10 7 cfu/ml significantly increased both prothrombin mRNA (fold changes in amnion: 4.1±1.9; chorion: 5.7±4.2; decidua: 10.0±5.4; FM: 9.2±3.0) and protein expression (fold changes in amnion: 138.0±44.0; chorion: 139.6±15.1; decidua: 56.9±29.1; fetal membrane: 133.1±40.0) compared to untreated controls. U. parvum at a dose of 1x10 6 cfu/ml significantly upregulated prothrombin protein expression in chorion cells (fold change: 54.9±5.3) and prothrombin mRNA expression in decidua cells (fold change: 4.4±1.9). Our results demonstrate that prothrombin can be directly produced by fetal membrane amnion, chorion, and decidua cells. Further, prothrombin production can be stimulated by U. parvum exposure in fetal membranes. These findings represent a potential novel underlying mechanism of U. parvum-induced rupture of fetal membranes. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Synaptic inhibition and excitation estimated via the time constant of membrane potential fluctuations

    DEFF Research Database (Denmark)

    Berg, Rune W.; Ditlevsen, Susanne

    2013-01-01

    and excitation and their confidence limits from single sweep trials. The estimates are based on the mean membrane potential, (V) , and the membrane time constant,τ. The time constant provides the total conductance (G = capacitance/τ) and is extracted from the autocorrelation of V. The synaptic conductances can...... then be inferred from (V) when approximating the neuron as a single compartment. We further employ a stochastic model to establish limits of confidence. The method is verified on models and experimental data, where the synaptic input is manipulated pharmacologically or estimated by an alternative method....... The method gives best results if the synaptic input is large compared to other conductances, the intrinsic conductances have little or no time dependence or are comparably small, the ligand gated kinetics is faster than the membrane time constant, and the majority of synaptic contacts are electrotonically...

  1. Comparative study of the energy potential of cyanide waters using two osmotic membrane modules under dead-end flow

    Science.gov (United States)

    García-Díaz, Y.; Quiñones-Bolaños, E.; Bustos-Blanco, C.; Vives-Pérez, L.; Bustillo-Lecompte, C.; Saba, M.

    2017-12-01

    The energy potential of the osmotic pressure gradient of cyanide waters is evaluated using two membrane modules, horizontal and vertical, operated under dead-end flow. The membrane was characterized using Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS). The membrane is mainly composed of carbon, oxygen, and sulphur. The properties of the membrane were unchanged and had no pore clogging after exposure to the cyanide waters. Potentials of 1.78×10-4 and 6.36×10-5Wm-2 were found for the horizontal and vertical modules, respectively, using the Van’t Hoff equation. Likewise, the permeability coefficient of the membrane was higher in the vertical module. Although the energy potential is low under the studied conditions the vertical configuration has a greater potential due to the action of gravity and the homogenous contact of the fluid with the membrane.

  2. Effect of triclocarban on membrane potential of rat thymocytes : Assessment with bis-(1,3-dibutylbarbituric acid)trimethine oxonol

    OpenAIRE

    Sun, Yuanzhi; Enkhjargal, Molomjamts; Sugihara, Aya; Yamada, Saki; Chen, Xiaohui; Miura, Yukari; Fukunaga, Eri; Satoh, Masaya; Oyama, Yasuo

    2013-01-01

    The effect of triclocarban (TCC), an environmental pollutant from household items and health care products, on membrane potential of rat thymocytes was examined by a flow cytometry with a fluorescent probe sensitive to membrane potential, bis-(1,3-dibutylbarbituric acid)trimethine oxonol, because TCC changes intracellular ionic circumstance that may affect the membrane potential. TCC at 0.3 μM or more (up to 3 μM) depolarized the membranes. This TCC-induced phenomenon was against our predicti...

  3. Electric field modulation of the membrane potential in solid-state ion channels.

    Science.gov (United States)

    Guan, Weihua; Reed, Mark A

    2012-12-12

    Biological ion channels are molecular devices that allow a rapid flow of ions across the cell membrane. Normal physiological functions, such as generating action potentials for cell-to-cell communication, are highly dependent on ion channels that can open and close in response to external stimuli for regulating ion permeation. Mimicking these biological functions using synthetic structures is a rapidly progressing yet challenging area. Here we report the electric field modulation of the membrane potential phenomena in mechanically and chemically robust solid-state ion channels, an abiotic analogue to the voltage-gated ion channels in living systems. To understand the complex physicochemical processes in the electric field regulated membrane potential behavior, both quasi-static and transient characteristics of converting transmembrane ion gradients into electric potential are investigated. It is found that the transmembrane potential can be adequately tuned by an external electrical stimulation, thanks to the unique properties of the voltage-regulated selective ion transport through a nanoscale channel.

  4. Sweetness-induced activation of membrane dipole potential in STC-1 taste cells.

    Science.gov (United States)

    Chen, Li-Chun; Xie, Ning-Ning; Deng, Shao-Ping

    2016-12-01

    The biological functions of cell membranes strongly influence the binding and transport of molecular species. We developed STC-1 cell line stably expressing the sweet taste receptor (T1R2/T1R3), and explored the possible correlation between sweeteners and membrane dipole potential of STC-1 cells. In this study, sweetener-induced dipole potential activation was elucidated using a fluorescence-based measurement technique, by monitoring the voltage sensitive probe Di-8-ANEPPS using a dual wavelength ratiometric approach. It indicated that the presence of sweeteners resulted in cell membrane dipole potential change, and interaction of artificial sweeteners with taste cells resulted in a greater reduction in potential compared with natural sweeteners. Our work presents a newly developed approach using a fluorescence-based measurement technique to study sweetener-induced dipole potential activation of STC-1 cells. This new approach could be used as a complementary tool to study the function of sweet taste receptors or other GPCRs and helps to understand the basis sweetness mechanism. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Simulated degradation of biochar and its potential environmental implications

    International Nuclear Information System (INIS)

    Liu, Zhaoyun; Demisie, Walelign; Zhang, Mingkui

    2013-01-01

    A simulated oxidation technique was used to examine the impacts of degradation on the surface properties of biochar and the potential implications of the changes in biochar properties were discussed. To simulate the short- and long-term environmental degradation, mild and harsh degradation were employed. Results showed that after mild degradation, the biochar samples showed significant reductions in surface area and pore volumes. After harsh degradation, the biochar samples revealed dramatic variations in their surface chemistry, surface area, pore volumes, morphology and adsorption properties. The results clearly indicate that changes of biochar surface properties were affected by biochar types and oxidative conditions. It is suggested that biochar surface properties are likely to be gradually altered during environmental exposure. This implies that these changes have potential effects for altering the physicochemical properties of biochar amended soils. -- Highlights: •Mild and harsh degradation were employed to simulate natural degradation of biochar. •Mild degradation could reduce the surface area and micropore volumes of biochar. •Harsh degradation caused severe changes of all of the biochar surface properties. •Biochar types and oxidative conditions may dominate the changes of its properties. -- The simulated degradation of biochar in this study could provide a mechanism for forecasting short- or long-term environmental degradation of biochar

  6. Zeta potential control in decontamination with inorganic membranes and inorganic adsorbents

    International Nuclear Information System (INIS)

    Andalaft, E.; Vega, R.; Correa, M.; Araya, R.; Loyola, P.

    1997-01-01

    The application of some advanced separation processes such as microfiltration and ultrafiltration, electroosmosis and electrodialysis for treating nuclear waste from different aqueous streams is under examination at the Chilean Commission for Nuclear Energy. The application of these techniques can be extended to regular industrial wastes when economically advisable. This report deals mainly with electrodialysis, electroosmosis and adsorption with inorganic materials. Special attention is paid to zeta potential control as a driving factor to electroosmosis. For radioactive contaminants that are present in the form of cations, anions, non-ionic solutions, colloids and suspended matter, appropriate combination of the processes may considerably increase the efficiency of processes used. As an example, colloids and suspended particles may be retained in porous ceramic membranes by nanofiltration, ultrafiltration or microfiltration depending on the particle size of the particles. The control of zeta potential by acting in the solid phase or else on the liquid phase has been studied; a mathematical model to predict electrodialysis data has been developed, and finally, the use of a home-made inorganic adsorbent illustrated. The effect of gamma irradiation on the membranes has also been studied. Properties such as salt retention, water flux and pore size diameter determined on both organic and inorganic membranes before and after irradiation indicate deterioration of the organic membrane. (author). 13 refs, 15 figs, 2 tabs

  7. SIMULATION OF THE LIGHT-INDUCED OSCILLATIONS OF THE MEMBRANE-POTENTIAL IN POTAMOGETON LEAF-CELLS

    NARCIS (Netherlands)

    MIEDEMA, H; PRINS, HBA

    An attempt has been made to simulate the light-induced oscillations of the membrane potential of Potamogeton lucens leaf cells in relation to the apoplastic pH changes. Previously it was demonstrated that the membrane potential of these cells can be described in terms of proton movements only. It is

  8. ECUT: Energy Conversion and Utilization Technologies program biocatalysis research activity. Potential membrane applications to biocatalyzed processes: Assessment of concentration polarization and membrane fouling

    Science.gov (United States)

    Ingham, J. D.

    1983-01-01

    Separation and purification of the products of biocatalyzed fermentation processes, such as ethanol or butanol, consumes most of the process energy required. Since membrane systems require substantially less energy for separation than most alternatives (e.g., distillation) they have been suggested for separation or concentration of fermentation products. This report is a review of the effects of concentration polarization and membrane fouling for the principal membrane processes: microfiltration, ultrafiltration, reverse osmosis, and electrodialysis including a discussion of potential problems relevant to separation of fermentation products. It was concluded that advanced membrane systems may result in significantly decreased energy consumption. However, because of the need to separate large amounts of water from much smaller amounts of product that may be more volatile than wate, it is not clear that membrane separations will necessarily be more efficient than alternative processes.

  9. Discovery of novel DENN proteins: implications for the evolution of eukaryotic intracellular membrane structures and human disease

    Directory of Open Access Journals (Sweden)

    Dapeng eZhang

    2012-12-01

    Full Text Available The tripartite DENN module, comprised of a N-terminal longin domain, followed by DENN and d-DENN domains, is a GDP-GTP exchange factor (GEFs for Rab GTPases, which are regulators of practically all membrane trafficking events in eukaryotes. Using sequence and structure analysis we identify multiple novel homologs of the DENN module, many of which can be traced back to the ancestral eukaryote. These findings provide unexpected leads regarding key cellular processes such as autophagy, vesicle-vacuole interactions, chromosome segregation and human disease. Of these, SMCR8, the folliculin interacting protein-1 and 2 (FNIP1 and FNIP2, nitrogen permease regulator 2 (NPR2 and NPR3 are proposed to function in recruiting Rab GTPases during different steps of autophagy, fusion of autophagosomes with the vacuole and regulation of cellular metabolism. Another novel DENN protein identified in this study is C9ORF72; expansions of the hexanucleotide GGGGCC in its first intron have been recently implicated in amyotrophic lateral sclerosis (ALS and fronto-temporal dementia (FTD. While this mutation is proposed to cause a RNA-level defect, the identification of C9ORF72 as a potential DENN-type GEF raises the possibility that at least part of the pathology might relate to a specific Rab-dependent vesicular trafficking process, as has been observed in the case of some other neurological conditions with similar phenotypes. We present evidence that the longin domain, such as those found in the DENN module, are likely to have been ultimately derived from the related domains found in prokaryotic GTPase-activating proteins of MglA-like GTPases. Thus, the origin of the longin domains from this ancient GTPase-interacting domain, concomitant with the radiation of GTPases, especially of the Rab clade, played an important role in the dynamics of eukaryotic intracellular membrane systems.

  10. Single-cell-based evaluation of sperm progressive motility via fluorescent assessment of mitochondria membrane potential.

    Science.gov (United States)

    Moscatelli, Natalina; Spagnolo, Barbara; Pisanello, Marco; Lemma, Enrico Domenico; De Vittorio, Massimo; Zara, Vincenzo; Pisanello, Ferruccio; Ferramosca, Alessandra

    2017-12-20

    Sperm cells progressive motility is the most important parameter involved in the fertilization process. Sperm middle piece contains mitochondria, which play a critical role in energy production and whose proper operation ensures the reproductive success. Notably, sperm progressive motility is strictly related to mitochondrial membrane potential (MMP) and consequently to mitochondrial functionality. Although previous studies presented an evaluation of mitochondrial function through MMP assessment in entire sperm cells samples, a quantitative approach at single-cell level could provide more insights in the analysis of semen quality. Here we combine laser scanning confocal microscopy and functional fluorescent staining of mitochondrial membrane to assess MMP distribution among isolated spermatozoa. We found that the sperm fluorescence value increases as a function of growing progressive motility and that such fluorescence is influenced by MMP disruptors, potentially allowing for the discrimination of different quality classes of sperm cells in heterogeneous populations.

  11. Effect of cadmium and lead on the membrane potential and photoelectric reaction of Nitellopsis obtusa cells.

    Science.gov (United States)

    Kurtyka, Renata; Burdach, Zbigniew; Karcz, Waldemar

    2011-03-01

    The effects of Cd and Pb on membrane potential (E(m)) and photoelectric reaction of Nitellopsis obtusa cells were investigated. It was found that Cd and Pb at 1.0 mM caused a depolarization of the E(m), whereas both metals at lower concentrations changed the E(m) in a different way. Pb at 0.1 mM and 0.01 mM hyperpolarized the E(m), whereas Cd at the same concentrations depolarized and did not change the E(m), respectively. In the presence of 0.01 mM Pb, the light-induced hyperpolarization of the E(m) was by 18% higher as compared to the control, whereas at 1.0 mM Pb it was by 40% lower. Pb at 0.1 mM and Cd at 0.01 mM or 5 × 0.01 mM did not change the light-induced membrane hyperpolarization. However, in the presence of Cd at 0.1 mM and 1.0 mM this hyperpolarization was 2-fold lower or was completely abolished, respectively. These results suggest that at high Cd and Pb concentrations both depolarization of the E(m) and decrease of light-induced membrane hyperpolarization in Nitellopsis obtusa cells are probably due to inhibition of the plasma membrane H(+)-ATPase activity, whereas both metals at lower concentrations differ in mechanism of membrane potential changes.

  12. Stabilization of mitochondrial membrane potential prevents doxorubicin-induced cardiotoxicity in isolated rat heart

    International Nuclear Information System (INIS)

    Montaigne, David; Marechal, Xavier; Baccouch, Riadh; Modine, Thomas; Preau, Sebastien; Zannis, Konstantinos; Marchetti, Philippe; Lancel, Steve; Neviere, Remi

    2010-01-01

    The present study was undertaken to examine the effects of doxorubicin on left ventricular function and cellular energy state in intact isolated hearts, and, to test whether inhibition of mitochondrial membrane potential dissipation would prevent doxorubicin-induced mitochondrial and myocardial dysfunction. Myocardial contractile performance and mitochondrial respiration were evaluated by left ventricular tension and its first derivatives and cardiac fiber respirometry, respectively. NADH levels, mitochondrial membrane potential and glucose uptake were monitored non-invasively via epicardial imaging of the left ventricular wall of Langendorff-perfused rat hearts. Heart performance was reduced in a time-dependent manner in isolated rat hearts perfused with Krebs-Henseleit solution containing 1 μM doxorubicin. Compared with controls, doxorubicin induced acute myocardial dysfunction (dF/dt max of 105 ± 8 mN/s in control hearts vs. 49 ± 7 mN/s in doxorubicin-treated hearts; *p < 0.05). In cardiac fibers prepared from perfused hearts, doxorubicin induced depression of mitochondrial respiration (respiratory control ratio of 4.0 ± 0.2 in control hearts vs. 2.2 ± 0.2 in doxorubicin-treated hearts; *p < 0.05) and cytochrome c oxidase kinetic activity (24 ± 1 μM cytochrome c/min/mg in control hearts vs. 14 ± 3 μM cytochrome c/min/mg in doxorubicin-treated hearts; *p < 0.05). Acute cardiotoxicity induced by doxorubicin was accompanied by NADH redox state, mitochondrial membrane potential, and glucose uptake reduction. Inhibition of mitochondrial permeability transition pore opening by cyclosporine A largely prevented mitochondrial membrane potential dissipation, cardiac energy state and dysfunction. These results suggest that in intact hearts an impairment of mitochondrial metabolism is involved in the development of doxorubicin cardiotoxicity.

  13. Effect of palytoxin on membrane and potential and current of frog myelinated fibers.

    Science.gov (United States)

    Dubois, J M; Cohen, J B

    1977-04-01

    Palytoxin is a highly toxic compound isolated form several zoanthid Palythoa species. The effects of palytoxin on the nodal membrane of frog myelinated fiber have been studied under current clamp and under voltage clamp conditions. Under current clamp conditions, palytoxin (0.1 microng/ml, 3 x 10(-8)M) induces a depolarization which is not reversed by washing. The resting potential reaches a value of -35 mV after 10 minutes. During the same period, the evoked action potential shows a gradual decline and finally disapears after about 30 minutes. The membrane depolarization is suppressed by removal of Na ions from the external medium, but only slightly diminished when tetrodotoxin (10(-6)M) is subsequently added to the external medium. When the potential of the nodal membrane is maintained at -70 mV, palytoxin (0.1 microng/ml) causes the appearance of an inward current that increases in magnitude during 30 minutes before attaining a steady-state value. The kinetics of development of that current is modified in the presence of tetrodotoxin or saxitoxin. Voltage clamp analysis shows that palytoxin causes an increase of the resting sodium permeability that is accompanied by a shift of the voltage dependence of the transient sodium permeability in the direction of membrane hyperpolarization. The shift in the voltage dependence of the transient permeability is accompanied by a decrease of the peak transient permeability. A similar shift in the potential dependence of the sodium inactivation is observed. During and after the application of palytoxin, the internal sodium concentration increases. The steady-state (potassium) conductance is also decreased at the same time as the leak current is increasing.

  14. The Na+,K+/H+-antiporter Nha1 influences the plasma membrane potential of Saccharomyces cerevisiae

    Czech Academy of Sciences Publication Activity Database

    Zimmermannová, Olga; Gášková, D.; Sychrová, Hana

    2006-01-01

    Roč. 6, č. 5 (2006), s. 792-800 ISSN 1567-1356 R&D Projects: GA AV ČR(CZ) IAA5011407; GA ČR(CZ) GP204/02/D092 Institutional research plan: CEZ:AV0Z50110509 Keywords : membrane potential * Na+,K+/H+ antiporter * diS-C3(3) assay Subject RIV: BO - Biophysics Impact factor: 2.274, year: 2006

  15. Generation of membrane potential beyond the conceptual range of Donnan theory and Goldman-Hodgkin-Katz equation.

    Science.gov (United States)

    Tamagawa, Hirohisa; Ikeda, Kota

    2017-09-01

    Donnan theory and Goldman-Hodgkin-Katz equation (GHK eq.) state that the nonzero membrane potential is generated by the asymmetric ion distribution between two solutions separated by a semipermeable membrane and/or by the continuous ion transport across the semipermeable membrane. However, there have been a number of reports of the membrane potential generation behaviors in conflict with those theories. The authors of this paper performed the experimental and theoretical investigation of membrane potential and found that (1) Donnan theory is valid only when the macroscopic electroneutrality is sufficed and (2) Potential behavior across a certain type of membrane appears to be inexplicable on the concept of GHK eq. Consequently, the authors derived a conclusion that the existing theories have some limitations for predicting the membrane potential behavior and we need to find a theory to overcome those limitations. The authors suggest that the ion adsorption theory named Ling's adsorption theory, which attributes the membrane potential generation to the mobile ion adsorption onto the adsorption sites, could overcome those problems.

  16. Bacteriophage removal in a full-scale membrane bioreactor (MBR) - Implications for wastewater reuse.

    Science.gov (United States)

    Purnell, Sarah; Ebdon, James; Buck, Austen; Tupper, Martyn; Taylor, Huw

    2015-04-15

    The aim of this study was to assess the potential removal efficacy of viruses in a full-scale membrane bioreactor (MBR) wastewater reuse system, using a range of indigenous and 'spiked' bacteriophages (phages) of known size and morphology. Samples were taken each week for three months from nine locations at each treatment stage of the water recycling plant (WRP) and tested for a range of microbiological parameters (n = 135). Mean levels of faecal coliforms were reduced to 0.3 CFU/100 ml in the MBR product and were undetected in samples taken after the chlorination stage. A relatively large reduction (5.3 log) in somatic coliphages was also observed following MBR treatment. However, F-specific and human-specific (GB124) phages were less abundant at all stages, and demonstrated log reductions post-MBR of 3.5 and 3.8, respectively. In 'spiking' experiments, suspended 'spiked' phages (MS2 and B-14) displayed post-MBR log reductions of 2.25 and 2.30, respectively. The removal of these suspended phages, which are smaller than the membrane pore size (0.04 μm), also highlights the possible role of the membrane biofilm as an effective additional barrier to virus transmission. The findings from this study of a full-scale MBR system demonstrate that the enumeration of several phage groups may offer a practical and conservative way of assessing the ability of MBR to remove enteric viruses of human health significance. They also suggest that phage removal in MBR systems may be highly variable and may be closely related on the one hand to both the size and morphology of the viruses and, on the other, to whether or not they are attached to solids. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Clinical Implications of Direct Immunofluorescence Findings in Patients With Ocular Mucous Membrane Pemphigoid.

    Science.gov (United States)

    Labowsky, Mary T; Stinnett, Sandra S; Liss, Jason; Daluvoy, Melissa; Hall, Russell P; Shieh, Christine

    2017-11-01

    To examine the clinical implications of positive or negative direct immunofluorescence biopsies (DIF) in patients with clinically typical ocular mucous membrane pemphigoid (MMP). Retrospective cohort study. The study population was patients with clinically typical ocular MMP disease with documented DIF results who were followed for at least 1 year at the Duke University multidisciplinary ocular MMP clinic. Data were collected by chart review and included patient demographics, clinical examination findings, and history of autoimmune disease and/or malignancy, as well as topical, systemic, and surgical treatments received. Main outcome measures included MMP Disease Area Index, Foster stages, proportion legally blind, duration of follow-up, and use of systemic immunosuppression and ocular procedures in treatment. In multivariable analysis restricted to 55 patients, patients with negative and positive biopsies were similar in the outcome measures; however, positive-biopsy patients were more likely to be treated with systemic immunosuppression and were followed for longer at our clinic. Patients with isolated ocular disease were also more likely to have negative biopsies compared to those who also had extraocular disease. Patients who had conjunctival biopsies were more likely to have a negative direct immunofluorescence result than patients with biopsies from other sites. We encourage clinicians and patients to consider treatment with systemic immunosuppression even in the absence of diagnosis confirmation by DIF. Furthermore, this study supports current standard of care to pursue a nonocular biopsy of normal-appearing, perilesional skin or oral mucosa when possible. Published by Elsevier Inc.

  18. The generation of resting membrane potentials in an inner ear hair cell system.

    Science.gov (United States)

    Bracho, H; Budelli, R

    1978-01-01

    1. The macula sacculi in the mudpuppy is an inner ear sensory area accessible for intracellular recordings in vitro and in vivo. 2. The resting potentials recorded in vitro can be explained by the electrodiffusion theory assuming a uniform ionic selective in the membranes of the neuroepithelial cells. 3. The resting potentials recorded in vivo are significantly larger than predicted by the electrodiffusion theory, probably because of an electrogenic metabolic process present in the neuroepithelial cells. 4. An equivalent circuit is proposed to explain the resting electrogenesis in the neuroepithelial cells present in the sensory area. Images Plate 1 PMID:702400

  19. Clusters of proteins in bio-membranes: insights into the roles of interaction potential shapes and of protein diversity

    OpenAIRE

    Meilhac, Nicolas; Destainville, Nicolas

    2011-01-01

    It has recently been proposed that proteins embedded in lipidic bio-membranes can spontaneously self-organize into stable small clusters, or membrane nano-domains, due to the competition between short-range attractive and longer-range repulsive forces between proteins, specific to these systems. In this paper, we carry on our investigation, by Monte Carlo simulations, of different aspects of cluster phases of proteins in bio-membranes. First, we compare different long-range potentials (includ...

  20. Correlation between membrane potential responses and tentacle movement in the dinoflagellate Noctiluca miliaris.

    Science.gov (United States)

    Oami, Kazunori

    2004-02-01

    Membrane potential responses and tentacle movement of the marine dinoflagellate Noctiluca miliaris were recorded simultaneously and their time relationships were examined. The food-gathering tentacle of Noctiluca exhibited slow extension-flexion movements in association with the spontaneously recurring membrane potential responses termed the tentacle regulating potentials (TRPs). The flexion of the tentacle began during the slow depolarization of the TRPs. The rate of the flexion increased after the hyperpolarizing (negative) spike following the slow depolarization. The tentacle then extended slowly during the hyperpolarized level of the TRPs. A TRPs-associated flexion did not occur when the external Ca(2+) ions were removed. On the contrary, the tentacle showed conspicuous flexion (coiling) when the external Ca(2+) concentration was raised. In association with the stimulus-evoked action potential, which triggers bioluminescent flash (flash-triggering action potential; FTP), the tentacle coiled quickly. The FTP-associated coiling took place even in the Ca(2+)-deprived condition. The coupling mechanisms of the TRPs-associated and FTP-associated tentacle movements were compared, and their biological significance was discussed.

  1. Vanadium As a Potential Membrane Material for Carbon Capture: Effects of Minor Flue Gas Species.

    Science.gov (United States)

    Yuan, Mengyao; Liguori, Simona; Lee, Kyoungjin; Van Campen, Douglas G; Toney, Michael F; Wilcox, Jennifer

    2017-10-03

    Vanadium and its surface oxides were studied as a potential nitrogen-selective membrane material for indirect carbon capture from coal or natural gas power plants. The effects of minor flue gas components (SO 2 , NO, NO 2 , H 2 O, and O 2 ) on vanadium at 500-600 °C were investigated by thermochemical exposure in combination with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and in situ X-ray diffraction (XRD). The results showed that SO 2 , NO, and NO 2 are unlikely to have adsorbed on the surface vanadium oxides at 600 °C after exposure for up to 10 h, although NO and NO 2 may have exhibited oxidizing effects (e.g., exposure to 250 ppmv NO/N 2 resulted in an 2.4 times increase in surface V 2 O 5 compared to exposure to just N 2 ). We hypothesize that decomposition of surface vanadium oxides and diffusion of surface oxygen into the metal bulk are both important mechanisms affecting the composition and morphology of the vanadium membrane. The results and hypothesis suggest that the carbon capture performance of the vanadium membrane can potentially be strengthened by material and process improvements such as alloying, operating temperature reduction, and flue gas treatment.

  2. Cell dualism: presence of cells with alternative membrane potentials in growing populations of bacteria and yeasts.

    Science.gov (United States)

    Ivanov, Volodymyr; Rezaeinejad, Saeid; Chu, Jian

    2013-10-01

    It is considered that all growing cells, for exception of acidophilic bacteria, have negatively charged inside cytoplasmic membrane (Δψ⁻-cells). Here we show that growing populations of microbial cells contain a small portion of cells with positively charged inside cytoplasmic membrane (Δψ⁺-cells). These cells were detected after simultaneous application of the fluorescent probes for positive membrane potential (anionic dye DIBAC⁻) and membrane integrity (propidium iodide, PI). We found in exponentially growing cell populations of Escherichia coli and Saccharomyces cerevisiae that the content of live Δψ⁻-cells was 93.6 ± 1.8 % for bacteria and 90.4 ± 4.0 % for yeasts and the content of live Δψ⁺-cells was 0.9 ± 0.3 % for bacteria and 2.4 ± 0.7 % for yeasts. Hypothetically, existence of Δψ⁺-cells could be due to short-term, about 1 min for bacteria and 5 min for yeasts, change of membrane potential from negative to positive value during the cell cycle. This change has been shown by the reversions of K⁺, Na⁺, and Ca²⁺ ions fluxes across the cell membrane during synchronous yeast culture. The transformation of Δψ(⁻-cells to Δψ⁺-cells can be explained by slow influx of K⁺ ions into Δψ⁻-cell to the trigger level of K⁺ concentration ("compression of potassium spring"), which is forming "alternative" Δψ⁺-cell for a short period, following with fast efflux of K⁺ ions out of Δψ⁺-cell ("release of potassium spring") returning cell to normal Δψ⁻ state. We anticipate our results to be a starting point to reveal the biological role of cell dualism in form of Δψ⁻- and Δψ⁺- cells.

  3. Learning of Precise Spike Times with Homeostatic Membrane Potential Dependent Synaptic Plasticity.

    Directory of Open Access Journals (Sweden)

    Christian Albers

    Full Text Available Precise spatio-temporal patterns of neuronal action potentials underly e.g. sensory representations and control of muscle activities. However, it is not known how the synaptic efficacies in the neuronal networks of the brain adapt such that they can reliably generate spikes at specific points in time. Existing activity-dependent plasticity rules like Spike-Timing-Dependent Plasticity are agnostic to the goal of learning spike times. On the other hand, the existing formal and supervised learning algorithms perform a temporally precise comparison of projected activity with the target, but there is no known biologically plausible implementation of this comparison. Here, we propose a simple and local unsupervised synaptic plasticity mechanism that is derived from the requirement of a balanced membrane potential. Since the relevant signal for synaptic change is the postsynaptic voltage rather than spike times, we call the plasticity rule Membrane Potential Dependent Plasticity (MPDP. Combining our plasticity mechanism with spike after-hyperpolarization causes a sensitivity of synaptic change to pre- and postsynaptic spike times which can reproduce Hebbian spike timing dependent plasticity for inhibitory synapses as was found in experiments. In addition, the sensitivity of MPDP to the time course of the voltage when generating a spike allows MPDP to distinguish between weak (spurious and strong (teacher spikes, which therefore provides a neuronal basis for the comparison of actual and target activity. For spatio-temporal input spike patterns our conceptually simple plasticity rule achieves a surprisingly high storage capacity for spike associations. The sensitivity of the MPDP to the subthreshold membrane potential during training allows robust memory retrieval after learning even in the presence of activity corrupted by noise. We propose that MPDP represents a biophysically plausible mechanism to learn temporal target activity patterns.

  4. Learning of Precise Spike Times with Homeostatic Membrane Potential Dependent Synaptic Plasticity.

    Science.gov (United States)

    Albers, Christian; Westkott, Maren; Pawelzik, Klaus

    2016-01-01

    Precise spatio-temporal patterns of neuronal action potentials underly e.g. sensory representations and control of muscle activities. However, it is not known how the synaptic efficacies in the neuronal networks of the brain adapt such that they can reliably generate spikes at specific points in time. Existing activity-dependent plasticity rules like Spike-Timing-Dependent Plasticity are agnostic to the goal of learning spike times. On the other hand, the existing formal and supervised learning algorithms perform a temporally precise comparison of projected activity with the target, but there is no known biologically plausible implementation of this comparison. Here, we propose a simple and local unsupervised synaptic plasticity mechanism that is derived from the requirement of a balanced membrane potential. Since the relevant signal for synaptic change is the postsynaptic voltage rather than spike times, we call the plasticity rule Membrane Potential Dependent Plasticity (MPDP). Combining our plasticity mechanism with spike after-hyperpolarization causes a sensitivity of synaptic change to pre- and postsynaptic spike times which can reproduce Hebbian spike timing dependent plasticity for inhibitory synapses as was found in experiments. In addition, the sensitivity of MPDP to the time course of the voltage when generating a spike allows MPDP to distinguish between weak (spurious) and strong (teacher) spikes, which therefore provides a neuronal basis for the comparison of actual and target activity. For spatio-temporal input spike patterns our conceptually simple plasticity rule achieves a surprisingly high storage capacity for spike associations. The sensitivity of the MPDP to the subthreshold membrane potential during training allows robust memory retrieval after learning even in the presence of activity corrupted by noise. We propose that MPDP represents a biophysically plausible mechanism to learn temporal target activity patterns.

  5. Learning of Precise Spike Times with Homeostatic Membrane Potential Dependent Synaptic Plasticity

    Science.gov (United States)

    Albers, Christian; Westkott, Maren; Pawelzik, Klaus

    2016-01-01

    Precise spatio-temporal patterns of neuronal action potentials underly e.g. sensory representations and control of muscle activities. However, it is not known how the synaptic efficacies in the neuronal networks of the brain adapt such that they can reliably generate spikes at specific points in time. Existing activity-dependent plasticity rules like Spike-Timing-Dependent Plasticity are agnostic to the goal of learning spike times. On the other hand, the existing formal and supervised learning algorithms perform a temporally precise comparison of projected activity with the target, but there is no known biologically plausible implementation of this comparison. Here, we propose a simple and local unsupervised synaptic plasticity mechanism that is derived from the requirement of a balanced membrane potential. Since the relevant signal for synaptic change is the postsynaptic voltage rather than spike times, we call the plasticity rule Membrane Potential Dependent Plasticity (MPDP). Combining our plasticity mechanism with spike after-hyperpolarization causes a sensitivity of synaptic change to pre- and postsynaptic spike times which can reproduce Hebbian spike timing dependent plasticity for inhibitory synapses as was found in experiments. In addition, the sensitivity of MPDP to the time course of the voltage when generating a spike allows MPDP to distinguish between weak (spurious) and strong (teacher) spikes, which therefore provides a neuronal basis for the comparison of actual and target activity. For spatio-temporal input spike patterns our conceptually simple plasticity rule achieves a surprisingly high storage capacity for spike associations. The sensitivity of the MPDP to the subthreshold membrane potential during training allows robust memory retrieval after learning even in the presence of activity corrupted by noise. We propose that MPDP represents a biophysically plausible mechanism to learn temporal target activity patterns. PMID:26900845

  6. High Altitude Emissions of Black Carbon Aerosols: Potential Climate Implications

    Science.gov (United States)

    Satheesh, S. K.

    2017-12-01

    these, it is hypothesized that such intrusions of black carbon to lower stratosphere and its consequent longer residence time in the stratosphere, would have significant implications for stratospheric chemistry, considering the known ozone depleting potential of black carbon aerosols.

  7. Peroxynitrite-mediated nitrosative stress decreases motility and mitochondrial membrane potential in human spermatozoa.

    Science.gov (United States)

    Uribe, P; Boguen, R; Treulen, F; Sánchez, R; Villegas, J V

    2015-03-01

    Nitrosative stress is produced by high levels of reactive nitrogen species (RNS). The RNS include peroxynitrite, a highly reactive free radical produced from a diffusion-controlled reaction between nitric oxide and superoxide anion. Peroxynitrite causes nitration and oxidation of lipids, proteins and DNA, and is thus considered an important pathogenic mechanism in various diseases. Although high levels of peroxynitrite are associated with astenozoospermia, few reports exist regarding the in vitro effect of high levels of this RNS on human sperm. The aim of this study was to evaluate the in vitro effect of nitrosative stress caused by peroxynitrite on the viability, motility and mitochondrial membrane potential of human spermatozoa. To do this, human spermatozoa from healthy donors were exposed in vitro to 3-morpholinosydnonimine (SIN-1), a molecule that generates peroxynitrite. Incubations were done at 37°C for up to 4 h with SIN-1 concentrations between 0.2 and 1.0 mmol/l. Generation of peroxynitrite was confirmed using dihydrorhodamine 123 (DHR) by spectrophotometry and flow cytometry. Sperm viability was assessed by propidium iodide staining; sperm motility was analyzed by CASA, and the state of mitochondrial membrane potential (ΔΨm) by JC-1 staining. Viability and ΔΨm were measured by flow cytometry. The results showed an increase in DHR oxidation, demonstrating the generation of peroxynitrite through SIN-1. Peroxynitrite decreased progressive and total motility, as well as some sperm kinetic parameters. Mitochondrial membrane potential also decreased. These alterations occurred with no decrease in sperm viability. In conclusion, peroxynitrite-induced nitrosative stress impairs vital functions in the male gamete, possibly contributing to male infertility. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Evaluation of mitochondrial membrane potential using a computerized device with a tetraphenylphosphonium-selective electrode

    Czech Academy of Sciences Publication Activity Database

    Labajová, A.; Vojtíšková, Alena; Křiváková, P.; Kofránek, J.; Drahota, Zdeněk; Houštěk, Josef

    2006-01-01

    Roč. 353, č. 1 (2006), s. 37-42 ISSN 0003-2697 R&D Projects: GA ČR(CZ) GD303/03/H065; GA ČR(CZ) GA303/06/1261 Grant - others:GA UK(CZ) 126/04/C; IGA MŠk(CZ) RP 394 Institutional research plan: CEZ:AV0Z50110509 Keywords : membrane potential * TPP -selective electrode Subject RIV: CE - Biochemistry Impact factor: 2.948, year: 2006

  9. Membrane potential and response properties of populations of cortical neurons in the high conductance state

    International Nuclear Information System (INIS)

    Moreno-Bote, Ruben; Parga, Nestor

    2005-01-01

    Because of intense synaptic activity, cortical neurons are in a high conductance state. We show that this state has important consequences on the properties of a population of independent model neurons with conductance-based synapses. Using an adiabaticlike approximation we study both the membrane potential and the firing probability distributions across the population. We find that the latter is bimodal in such a way that at any particular moment some neurons are inactive while others are active. The population rate and the response variability are also characterized

  10. Efficient hydrogen isotopologues separation through a tunable potential barrier: The case of a C2N membrane

    OpenAIRE

    Qu, Yuanyuan; Li, Feng; Zhao, Mingwen

    2017-01-01

    Isotopes separation through quantum sieving effect of membranes is quite promising for industrial applications. For the light hydrogen isotopologues (eg. H2, D2), the confinement of potential wells in porous membranes to isotopologues was commonly regarded to be crucial for highly efficient separation ability. Here, we demonstrate from first-principles that a potential barrier is also favorable for efficient hydrogen isotopologues separation. Taking an already-synthesized two-dimensional carb...

  11. Ligand partitioning into lipid bilayer membranes under high pressure: Implication of variation in phase-transition temperatures.

    Science.gov (United States)

    Matsuki, Hitoshi; Kato, Kentaro; Okamoto, Hirotsugu; Yoshida, Shuntaro; Goto, Masaki; Tamai, Nobutake; Kaneshina, Shoji

    2017-12-01

    The variation in phase-transition temperatures of dipalmitoylphosphatidylcholine (DPPC) bilayer membrane by adding two membrane-active ligands, a long-chain fatty acid (palmitic acid (PA)) and an inhalation anesthetic (halothane (HAL)), was investigated by light-transmittance measurements and fluorometry. By assuming the thermodynamic colligative property for the bilayer membrane at low ligand concentrations, the partitioning behavior of these ligands into the DPPC bilayer membrane was considered. It was proved from the differential partition coefficients between two phases that PA has strong affinity with the gel (lamellar gel) phase in a micro-molal concentration range and makes the bilayer membrane more ordered, while HAL has strong affinity with the liquid crystalline phase in a milli-molal concentration range and does the bilayer membrane more disordered. The transfer volumes of both ligands from the aqueous solution to each phase of the DPPC bilayer membrane showed that the preferential partitioning of the PA molecule into the gel (lamellar gel) produces about 20% decrease in transfer volume as compared with the liquid crystalline phase, whereas that of the HAL molecule into the liquid crystalline phase does about twice increase in transfer volume as compared with the gel (ripple gel) phase. Furthermore, changes in thermotropic and barotropic phase behavior of the DPPC bilayer membrane by adding the ligand was discussed from the viewpoint of the ligand partitioning. Reflecting the contrastive partitioning of PA and HAL into the pressure-induced interdigitated gel phase among the gel phases, it was revealed that PA suppresses the formation of the interdigitated gel phase under high pressure while HAL promotes it. These results clearly indicate that each phase of the DPPC bilayer membrane has a potential to recognize various ligand molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

    Directory of Open Access Journals (Sweden)

    Vorleak Chea

    2014-10-01

    Full Text Available This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR. The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1, consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2, whereas at the highest substrate concentration (500 mg·L−1, it was shown that the reaction was limited by the oxygen content.

  13. Excess chemical potential of small solutes across water--membrane and water--hexane interfaces

    Science.gov (United States)

    Pohorille, A.; Wilson, M. A.

    1996-01-01

    The excess chemical potentials of five small, structurally related solutes, CH4, CH3F, CH2F2, CHF3, and CF4, across the water-glycerol 1-monooleate bilayer and water-hexane interfaces were calculated at 300, 310, and 340 K using the particle insertion method. The excess chemical potentials of nonpolar molecules (CH4 and CF4) decrease monotonically or nearly monotonically from water to a nonpolar phase. In contrast, for molecules that possess permanent dipole moments (CH3F, CH2F, and CHF3), the excess chemical potentials exhibit an interfacial minimum that arises from superposition of two monotonically and oppositely changing contributions: electrostatic and nonelectrostatic. The nonelectrostatic term, dominated by the reversible work of creating a cavity that accommodates the solute, decreases, whereas the electrostatic term increases across the interface from water to the membrane interior. In water, the dependence of this term on the dipole moment is accurately described by second order perturbation theory. To achieve the same accuracy at the interface, third order terms must also be included. In the interfacial region, the molecular structure of the solvent influences both the excess chemical potential and solute orientations. The excess chemical potential across the interface increases with temperature, but this effect is rather small. Our analysis indicates that a broad range of small, moderately polar molecules should be surface active at the water-membrane and water-oil interfaces. The biological and medical significance of this result, especially in relation to the mechanism of anesthetic action, is discussed.

  14. Oxygen transport by oxygen potential gradient in dense ceramic oxide membranes

    Energy Technology Data Exchange (ETDEWEB)

    Maiya, P.S.; Balachandran, U.; Dusek, J.T.; Mieville, R.L. [Argonne National Lab., IL (United States). Energy Technology Div.; Kleefisch, M.S.; Udovich, C.A. [Amoco Exploration/Production, Naperville, IL (United States)

    1996-05-01

    Numerous studies have been conducted in recent years on the partial oxidation of methane to synthesis gas (syngas: CO + H{sub 2}) with air as the oxidant. In partial oxidation, a mixed-oxide ceramic membrane selectively transports oxygen from the air; this transport is driven by the oxygen potential gradient. Of the several ceramic materials the authors have tested, a mixed oxide based on the Sr-Fe-Co-O system has been found to be very attractive. Extensive oxygen permeability data have been obtained for this material in methane conversion experiments carried out in a reactor. The data have been analyzed by a transport equation based on the phenomenological theory of diffusion under oxygen potential gradients. Thermodynamic calculations were used to estimate the driving force for the transport of oxygen ions. The results show that the transport equation deduced from the literature describes the permeability data reasonably well and can be used to determine the diffusion coefficients and the associated activation energy of oxygen ions in the ceramic membrane material.

  15. Membrane potential responses to ionophoretically applied alpha-adrenoceptor agonists in the mouse anococcygeus muscle.

    Science.gov (United States)

    Large, W. A.

    1983-01-01

    1 Noradrenaline phenylephrine, naphazoline and oxymetazoline were applied by ionophoresis to the mouse anococcygeus muscle and the membrane potential was recorded with an intracellular microelectrode. 2 The ionophoretic application of noradrenaline and phenylephrine produced dose-related depolarizations in 96% of the cells tested; in contrast, naphazoline and oxymetazoline depolarized only 62% of the cells although contraction was always seen. 3 The depolarizations produced by all four drugs had similar characteristics in shape and time course except that the latency of responses induced by the imidazoline-related drugs was significantly longer than the value obtained with the phenylethanolamines. This discrepancy was not due to the difference in susceptibility to neuronal uptake of the two groups of drugs. 4 The time to peak depolarization for naphazoline and oxymetazoline was longer than that for noradrenaline and phenylephrine but was not sufficient to account for the considerably slower contraction produced by the former drugs. 5 At room temperature the sensitivity of the mouse anococcygeus to ionophoretically applied naphazoline and oxymetazoline was significantly lower than that to noradrenaline and phenylephrine but at 35 degrees C the sensitivity was similar for all drugs. 6 These results suggest that there might be two subclasses of alpha 1-adrenoceptor in the mouse anococcygeus; stimulation of one type leads to depolarization and contraction and activation of the other class produces contraction with no change in membrane potential. PMID:6135476

  16. Membrane phase separations, asymmetry and implications in the origin of life

    International Nuclear Information System (INIS)

    Eze, M.O.

    1993-11-01

    Membrane lipids, by affecting membrane physical state, influence solute transport as in Escherichia coli, and play a prominent role in homeoviscous (homeophasic) adaptation whereby cells adapt to varying temperatures. Thus, on prebiotic earth, lipid-doped precells were possibly stabilized. Studies to investigate this hypothesis are advocated. (author). 19 refs, 4 figs

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

    Science.gov (United States)

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

    2016-06-05

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

  18. Grape tannin catechin and ethanol fluidify oral membrane mimics containing moderate amounts of cholesterol: Implications on wine tasting?

    Science.gov (United States)

    Furlan, Aurélien L; Saad, Ahmad; Dufourc, Erick J; Géan, Julie

    2016-11-01

    Wine tasting results in interactions of tannin-ethanol solutions with proteins and lipids of the oral cavity. Among the various feelings perceived during tasting, astringency and bitterness most probably result in binding events with saliva proteins, lipids and receptors. In this work, we monitored the conjugated effect of the grape polyphenol catechin and ethanol on lipid membranes mimicking the different degrees of keratinization of oral cavity surfaces by varying the amount of cholesterol present in membranes. Both catechin and ethanol fluidify the membranes as evidenced by solid-state 2 H NMR of perdeuterated lipids. The effect is however depending on the cholesterol proportion and may be very important and cumulative in the absence of cholesterol or presence of 18 mol % cholesterol. For 40 mol % cholesterol, mimicking highly keratinized membranes, both ethanol and catechin can no longer affect membrane dynamics. These observations can be accounted for by phase diagrams of lipid-cholesterol mixtures and the role played by membrane defects for insertion of tannins and ethanol when several phases coexist. These findings suggest that the behavior of oral membranes in contact with wine should be different depending of their cholesterol content. Astringency and bitterness could be then affected; the former because of a potential competition between the tannin-lipid and the tannin-saliva protein interaction, and the latter because of a possible fluidity modification of membranes containing taste receptors. The lipids that have been up to now weakly considered in oenology may be become a new actor in the issue of wine tasting. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  19. Effect of Gating Modifier Toxins on Membrane Thickness: Implications for Toxin Effect on Gramicidin and Mechanosensitive Channels

    Directory of Open Access Journals (Sweden)

    Shin-Ho Chung

    2013-02-01

    Full Text Available Various gating modifier toxins partition into membranes and interfere with the gating mechanisms of biological ion channels. For example, GsMTx4 potentiates gramicidin and several bacterial mechanosensitive channels whose gating kinetics are sensitive to mechanical properties of the membrane, whereas binding of HpTx2 shifts the voltage-activity curve of the voltage-gated potassium channel Kv4.2 to the right. The detailed process by which the toxin partitions into membranes has been difficult to probe using molecular dynamics due to the limited time scale accessible. Here we develop a protocol that allows the spontaneous assembly of a polypeptide toxin into membranes in atomistic molecular dynamics simulations of tens of nanoseconds. The protocol is applied to GsMTx4 and HpTx2. Both toxins, released in water at the start of the simulation, spontaneously bind into the lipid bilayer within 50 ns, with their hydrophobic patch penetrated into the bilayer beyond the phosphate groups of the lipids. It is found that the bilayer is about 2 Å thinner upon the binding of a GsMTx4 monomer. Such a thinning effect of GsMTx4 on membranes may explain its potentiation effect on gramicidin and mechanosensitive channels.

  20. EMBO workshop al fin del mundo: a meeting on membrane trafficking and its implication for polarity and diseases.

    Science.gov (United States)

    Marzolo, María-Paz; Faundez, Victor; Galli, Thierry

    2015-07-01

    The EMBO worskhop at the "end of the world'" (al fin del mundo), a meeting on membrane trafficking and its implication for polarity and diseases, took place in the Chilean Patagonia surrounded by the landscapes once witnessed by Charles Darwin. The meeting showcased some of the best membrane trafficking science with an emphasis in neuroscience and disease models. Speakers from Europe, USA, South America and the graduate students behind it; embarked on an enthusiastic and eclectic dialog where a wide range of cell types, model genetic systems, and diseases where discussed. This meeting demonstrated the power of trafficking concepts to integrate diverse biology and to formulate mechanisms of normal and disease cells. © 2015 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

  1. Chemisorption of estrone in nylon microfiltration membranes: Adsorption mechanism and potential use for estrone removal from water.

    Science.gov (United States)

    Han, Jie; Qiu, Wei; Hu, Jiangyong; Gao, Wei

    2012-03-01

    Estrone is a representative steroid estrogen contaminant that has been detected in effluents from sewage treatment facilities, as well as in surface and ground waters. Our study shows that estrone can be readily removed from water via a unique chemisorption mechanism using nylon microfiltration membranes. Experiments on a laboratory in-line filtration system showed instant removal of estrone from 200 μg/l aqueous solutions by 0.45-μm nylon membranes (ca. 35 L per m(2) membrane). Comparisons with 0.45-μm PVDF, PTFE and glass microfiber membranes suggested that the significant estrone adsorption in nylon membrane should be predominately driven by a different mechanism rather than common physical adsorption. Fourier transform infrared spectroscopy study on nylon membranes and a model compound, N-methylacetamide, showed that the significant adsorption originated from the hydrogen bonding between terminal -OH groups on estrone molecules and nucleophile -C=O groups in amide groups of nylon 6,6. The saturated nylon membrane showed very low leachability in ambient water, while it could be effectively regenerated in alkaline or ethanol solutions. Preliminary reusability study showed that the membrane maintained a consistent adsorption capacity for estrone during ten cycles of reuse. The chemisorption-based polymeric adsorption may provide a new alternative approach for removing estrone and potentially other trace organic contaminants from water. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Variations in mitochondrial membrane potential correlate with malic acid production by natural isolates of Saccharomyces cerevisiae sake strains.

    Science.gov (United States)

    Oba, Takahiro; Kusumoto, Kenichi; Kichise, Yuki; Izumoto, Eiji; Nakayama, Shunichi; Tashiro, Kosuke; Kuhara, Satoru; Kitagaki, Hiroshi

    2014-08-01

    Research on the relationship between mitochondrial membrane potential and fermentation profile is being intensely pursued because of the potential for developing advanced fermentation technologies. In the present study, we isolated naturally occurring strains of yeast from sake mash that produce high levels of malic acid and demonstrate that variations in mitochondrial membrane potential correlate with malic acid production. To define the underlying biochemical mechanism, we determined the activities of enzymes required for malic acid synthesis and found that pyruvate carboxylase and malate dehydrogenase activities in strains that produce high levels of malic acid were elevated compared with the standard sake strain K901. These results inspired us to hypothesize that decreased mitochondrial membrane potential was responsible for increased malic acid synthesis, and we present data supporting this hypothesis. Thus, the mitochondrial membrane potential of high malic acid producers was lower compared with standard strains. We conclude that mitochondrial membrane potential correlates with malic acid production. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  3. Electrospun nanofibrous SF/P(LLA-CL membrane: a potential substratum for endothelial keratoplasty

    Directory of Open Access Journals (Sweden)

    Chen JZ

    2015-05-01

    had different light transmittance properties. The 25:75 blended ratio membrane had the best transmittance among these scaffolds. All electrospun nanofibrous membranes showed improved speed of cell adherence when compared with the control group, especially when the P(LLA-CL ratio increased. The 25:75 blended ratio membranes also had the highest cell proliferation. B4G12 cells could form a monolayer on all scaffolds, and most functional genes were also stably expressed on all scaffolds. Only two genes showed changes in expression.Conclusion: All blended ratios of SF:P(LLA-CL scaffolds were evaluated and showed good biocompatibility for cell adherence and monolayer formation. Among them, the 25:75 blended ratio SF:P(LLA-CL scaffold had the best transmittance and the highest cell proliferation. These attributes further the potential application of the SF:P(LLA-CL scaffold for corneal endothelial transplantation. Keywords: silk fibroin, poly(L-lactic acid-co-Ɛ-caprolactone, B4G12, corneal endothelium, regeneration

  4. Modeling of the axon membrane skeleton structure and implications for its mechanical properties.

    Directory of Open Access Journals (Sweden)

    Yihao Zhang

    2017-02-01

    Full Text Available Super-resolution microscopy recently revealed that, unlike the soma and dendrites, the axon membrane skeleton is structured as a series of actin rings connected by spectrin filaments that are held under tension. Currently, the structure-function relationship of the axonal structure is unclear. Here, we used atomic force microscopy (AFM to show that the stiffness of the axon plasma membrane is significantly higher than the stiffnesses of dendrites and somata. To examine whether the structure of the axon plasma membrane determines its overall stiffness, we introduced a coarse-grain molecular dynamics model of the axon membrane skeleton that reproduces the structure identified by super-resolution microscopy. Our proposed computational model accurately simulates the median value of the Young's modulus of the axon plasma membrane determined by atomic force microscopy. It also predicts that because the spectrin filaments are under entropic tension, the thermal random motion of the voltage-gated sodium channels (Nav, which are bound to ankyrin particles, a critical axonal protein, is reduced compared to the thermal motion when spectrin filaments are held at equilibrium. Lastly, our model predicts that because spectrin filaments are under tension, any axonal injuries that lacerate spectrin filaments will likely lead to a permanent disruption of the membrane skeleton due to the inability of spectrin filaments to spontaneously form their initial under-tension configuration.

  5. Hydraulic fracturing water use variability in the United States and potential environmental implications.

    Science.gov (United States)

    Gallegos, Tanya J; Varela, Brian A; Haines, Seth S; Engle, Mark A

    2015-07-01

    A U.S. map of water volumes used to hydraulically fracture oil and gas wells, 2011-2014Hydraulic fracturing water volumes differ regionally across the U.S.Discussion of variation in water use and potential environmental implications.

  6. Oversampling method to extract excitatory and inhibitory conductances from single-trial membrane potential recordings.

    Science.gov (United States)

    Bédard, Claude; Béhuret, Sebastien; Deleuze, Charlotte; Bal, Thierry; Destexhe, Alain

    2012-09-15

    Variations of excitatory and inhibitory conductances determine the membrane potential (V(m)) activity of neurons, as well as their spike responses, and are thus of primary importance. Methods to estimate these conductances require clamping the cell at several different levels of V(m), thus making it impossible to estimate conductances from "single trial" V(m) recordings. We present here a new method that allows extracting estimates of the full time course of excitatory and inhibitory conductances from single-trial V(m) recordings. This method is based on oversampling of the V(m). We test the method numerically using models of increasing complexity. Finally, the method is evaluated using controlled conductance injection in cortical neurons in vitro using the dynamic-clamp technique. This conductance extraction method should be very useful for future in vivo applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. The Involvement of Mitochondrial Membrane Potential in Cross-Resistance Between Radiation and Docetaxel

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahara, Yoshikazu [Department of Radiation Biology and Medicine, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai (Japan); Department of Pathology, Institute of Development, Aging and Cancer, Tohoku University, Sendai (Japan); Roudkenar, Mehryar Habibi; Suzuki, Masatoshi; Urushihara, Yusuke; Fukumoto, Motoi [Department of Pathology, Institute of Development, Aging and Cancer, Tohoku University, Sendai (Japan); Saito, Yohei [Department of Radiopharmacy, Tohoku Medical and Pharmaceutical University, Sendai (Japan); Fukumoto, Manabu, E-mail: manabu.fukumoto.a8@tohoku.ac.jp [Department of Pathology, Institute of Development, Aging and Cancer, Tohoku University, Sendai (Japan); Department of Molecular Pathology, Tokyo Medical University, Tokyo (Japan)

    2016-11-01

    Purpose: To understand the molecular mechanisms underlying cancer cell radioresistance, clinically relevant radioresistant (CRR) cells that continue to proliferate during exposure to 2 Gy/day X-rays for more than 30 days were established. A modified high-density survival assay for anticancer drug screening revealed that CRR cells were resistant to an antimicrotubule agent, docetaxel (DTX). The involvement of reactive oxygen species (ROS) from mitochondria (mtROS) in the cross-resistance to X-rays and DTX was studied. Methods and Materials: Sensitivity to anticancer agents was determined by a modified high-density cell survival or water-soluble tetrazolium salt assay. DTX-induced mtROS generation was determined by MitoSOX red staining. JC-1 staining was used to visualize mitochondrial membrane potential. DTX-induced DNA double-strand breaks were determined by γ-H2AX staining. To obtain mitochondrial DNA-lacking (ρ{sup 0}) cells, the cells were cultured for 3 to 4 weeks in medium containing ethidium bromide. Results: Treatment with DTX increased mtROS in parental cells but not in CRR cells. DTX induced DNA double-strand breaks in parental cells. The mitochondrial membrane potential of CRR cells was lower in CRR cells than in parental cells. Depletion of mtDNA induced DTX resistance in parental cells. Treatment with dimethyl sulfoxide also induced DTX resistance in parental cells. Conclusions: The mitochondrial dysfunction observed in CRR cells contributes to X-ray and DTX cross-resistance. The activation of oxidative phosphorylation in CRR cells may represent an effective approach to overcome radioresistant cancers. In general, the overexpression of β-tubulin or multidrug efflux pumps is thought to be involved in DTX resistance. In the present study, we discovered another DTX resistant mechanism by investigating CRR cells.

  8. Potential Clinical Implications of the Urotensin II Receptor Antagonists

    Directory of Open Access Journals (Sweden)

    Emilie Kane

    2011-07-01

    Full Text Available Urotensin-II (UII, which binds to its receptor UT, plays an important role in the heart, kidneys, pancreas, adrenal gland and CNS. In the vasculature, it acts as a potent endothelium-independent vasoconstrictor and endothelium-dependent vasodilator. In disease states, this constriction-dilation equilibrium is disrupted. There is an upregulation of the UII system in heart disease, metabolic syndrome and kidney failure. The increase in UII release and UT expression suggest that UII system may be implicated in the pathology and pathogenesis of these diseases by causing an increase in ACAT-1 activity leading to SMC proliferation and foam cell infiltration, insulin resistance (DMII, as well as inflammation, high blood pressure and plaque formation. Recently, UT antagonists such as SB-611812, palosuran, and most recently a piperazino-isoindolinone based antagonist have been developed in the hope of better understanding the UII system and treating its associated diseases.

  9. NS309 decreases rat detrusor smooth muscle membrane potential and phasic contractions by activating SK3 channels

    Science.gov (United States)

    Parajuli, Shankar P; Hristov, Kiril L; Soder, Rupal P; Kellett, Whitney F; Petkov, Georgi V

    2013-01-01

    Background and Purpose Overactive bladder (OAB) is often associated with abnormally increased detrusor smooth muscle (DSM) contractions. We used NS309, a selective and potent opener of the small or intermediate conductance Ca2+-activated K+ (SK or IK, respectively) channels, to evaluate how SK/IK channel activation modulates DSM function. Experimental Approach We employed single-cell RT-PCR, immunocytochemistry, whole cell patch-clamp in freshly isolated rat DSM cells and isometric tension recordings of isolated DSM strips to explore how the pharmacological activation of SK/IK channels with NS309 modulates DSM function. Key Results We detected SK3 but not SK1, SK2 or IK channels expression at both mRNA and protein levels by RT-PCR and immunocytochemistry in DSM single cells. NS309 (10 μM) significantly increased the whole cell SK currents and hyperpolarized DSM cell resting membrane potential. The NS309 hyperpolarizing effect was blocked by apamin, a selective SK channel inhibitor. NS309 inhibited the spontaneous phasic contraction amplitude, force, frequency, duration and tone of isolated DSM strips in a concentration-dependent manner. The inhibitory effect of NS309 on spontaneous phasic contractions was blocked by apamin but not by TRAM-34, indicating no functional role of the IK channels in rat DSM. NS309 also significantly inhibited the pharmacologically and electrical field stimulation-induced DSM contractions. Conclusions and Implications Our data reveal that SK3 channel is the main SK/IK subtype in rat DSM. Pharmacological activation of SK3 channels with NS309 decreases rat DSM cell excitability and contractility, suggesting that SK3 channels might be potential therapeutic targets to control OAB associated with detrusor overactivity. PMID:23145946

  10. Reassessing Wind Potential Estimates for India: Economic and Policy Implications

    Energy Technology Data Exchange (ETDEWEB)

    Phadke, Amol; Bharvirkar, Ranjit; Khangura, Jagmeet

    2011-09-15

    We assess developable on-shore wind potential in India at three different hub-heights and under two sensitivity scenarios – one with no farmland included, the other with all farmland included. Under the “no farmland included” case, the total wind potential in India ranges from 748 GW at 80m hub-height to 976 GW at 120m hub-height. Under the “all farmland included” case, the potential with a minimum capacity factor of 20 percent ranges from 984 GW to 1,549 GW. High quality wind energy sites, at 80m hub-height with a minimum capacity factor of 25 percent, have a potential between 253 GW (no farmland included) and 306 GW (all farmland included). Our estimates are more than 15 times the current official estimate of wind energy potential in India (estimated at 50m hub height) and are about one tenth of the official estimate of the wind energy potential in the US.

  11. Zinc oxide nanoparticles mediated cytotoxicity, mitochondrial membrane potential and level of antioxidants in presence of melatonin.

    Science.gov (United States)

    Sruthi, S; Millot, N; Mohanan, P V

    2017-10-01

    Zinc oxide nanoparticles (ZnO NPs) are widely used in a variety of products and are currently being investigated for biomedical applications. However, they have the potential to interact with macromolecules like proteins, lipids and DNA within the cells which makes the safe biomedical application difficult. The toxicity of the ZnO NP is mainly attributed reactive oxygen species (ROS) generation. Different strategies like iron doping, polymer coating and external supply of antioxidants have been evaluated to minimize the toxic potential of ZnO NPs. Melatonin is a hormone secreted by the pineal gland with great antioxidant properties. The melatonin is known to protect cells from ROS inducing external agents like lipopolysaccharides. In the present study, the protective effect of melatonin on ZnO NPs mediated toxicity was evaluated using C6 glial cells. The Cytotoxicity, mitochondrial membrane potential and free radical formation were measured to study the effect of melatonin. Antioxidant assays were done on mice brain slices, incubated with melatonin and ZnO NPs. The results of the study reveal that, instead of imparting a protective effect, the melatonin pre-treatment enhanced the toxicity of ZnO NPs. Melatonin increased antioxidant enzymes in brain slices. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Toxins in botanical dietary supplements: blue cohosh components disrupt cellular respiration and mitochondrial membrane potential.

    Science.gov (United States)

    Datta, Sandipan; Mahdi, Fakhri; Ali, Zulfiqar; Jekabsons, Mika B; Khan, Ikhlas A; Nagle, Dale G; Zhou, Yu-Dong

    2014-01-24

    Certain botanical dietary supplements have been associated with idiosyncratic organ-specific toxicity. Similar toxicological events, caused by drug-induced mitochondrial dysfunction, have forced the withdrawal or U.S. FDA "black box" warnings of major pharmaceuticals. To assess the potential mitochondrial liability of botanical dietary supplements, extracts from 352 authenticated plant samples used in traditional Chinese, Ayurvedic, and Western herbal medicine were evaluated for the ability to disrupt cellular respiration. Blue cohosh (Caulophyllum thalictroides) methanol extract exhibited mitochondriotoxic activity. Used by some U.S. midwives to help induce labor, blue cohosh has been associated with perinatal stroke, acute myocardial infarction, congestive heart failure, multiple organ injury, and neonatal shock. The potential link between mitochondrial disruption and idiosyncratic herbal intoxication prompted further examination. The C. thalictroides methanol extract and three saponins, cauloside A (1), saponin PE (2), and cauloside C (3), exhibited concentration- and time-dependent mitochondriotoxic activities. Upon treatment, cell respiration rate rapidly increased and then dramatically decreased within minutes. Mechanistic studies revealed that C. thalictroides constituents impair mitochondrial function by disrupting membrane integrity. These studies provide a potential etiological link between this mitochondria-sensitive form of cytotoxicity and idiosyncratic organ damage.

  13. Amniotic membrane-derived stem cells: immunomodulatory properties and potential clinical application

    Directory of Open Access Journals (Sweden)

    Insausti CL

    2014-03-01

    Full Text Available Carmen L Insausti,1 Miguel Blanquer,1 Ana M García-Hernández,1 Gregorio Castellanos,2 José M Moraleda11Unidad de Trasplante Hematopoyético y Terapia Celular, 2Servicio de Cirugía, Hospital Clínico Universitario Virgen de la Arrixaca, IMIB, Campus Mare Nostrum, Universidad de Murcia, El Palmar, Murcia, SpainAbstract: Epithelial and mesenchymal cells isolated from the amniotic membrane (AM possess stem cell characteristics, differentiation potential toward lineages of different germ layers, and immunomodulatory properties. While their expansion and differentiation potential have been well studied and characterized, knowledge about their immunomodulatory properties and the mechanisms involved is still incomplete. These mechanisms have been evaluated on various target cells of the innate and the adaptive system and in animal models of different inflammatory diseases. Some results have evidenced that the immunomodulatory effect of AM-derived cells is dependent on cell-cell contact, but many of them have demonstrated that these properties are mediated through the secretion of suppressive molecules. In this review, we present an update on the described immunomodulatory properties of the derived amniotic cells and some of the proposed involved mechanisms. Furthermore, we describe some assays in animal models of different inflammatory diseases which reveal the potential use of these cells to treat such diseases.Keywords: epithelial cells, mesenchymal cells, cell therapy, immunomodulation

  14. Heparan Sulfate: A Potential Candidate for the Development of Biomimetic Immunomodulatory Membranes

    Directory of Open Access Journals (Sweden)

    Bruna Corradetti

    2017-09-01

    Full Text Available Clinical trials have demonstrated that heparan sulfate (HS could be used as a therapeutic agent for the treatment of inflammatory diseases. Its anti-inflammatory effect makes it suitable for the development of biomimetic innovative strategies aiming at modulating stem cells behavior toward a pro-regenerative phenotype in case of injury or inflammation. Here, we propose collagen type I meshes fabricated by solvent casting and further crosslinked with HS (HS-Col to create a biomimetic environment resembling the extracellular matrix of soft tissue. HS-Col meshes were tested for their capability to provide physical support to stem cells’ growth, maintain their phenotypes and immunosuppressive potential following inflammation. HS-Col effect on stem cells was investigated in standard conditions as well as in an inflammatory environment recapitulated in vitro through a mix of pro-inflammatory cytokines (tumor necrosis factor-α and interferon-gamma; 20 ng/ml. A significant increase in the production of molecules associated with immunosuppression was demonstrated in response to the material and when cells were grown in presence of pro-inflammatory stimuli, compared to bare collagen membranes (Col, leading to a greater inhibitory potential when mesenchymal stem cells were exposed to stimulated peripheral blood mononuclear cells. Our data suggest that the presence of HS is able to activate the molecular machinery responsible for the release of anti-inflammatory cytokines, potentially leading to a faster resolution of inflammation.

  15. Membrane Fouling Potential of Secondary Effluent Organic Matter (EfOM) from Conventional Activated Sludge Process

    KAUST Repository

    Wei, Chunhai

    2012-01-01

    Secondary effluent organic matter (EfOM) from a conventional activated sludge process was filtered through constant-pressure dead-end filtration tests with a sequential ultrafiltration (UF, molecular weight cut-off (MWCO) of 10k Dalton) and nanofiltration (NF, MWCO of 200 Dalton) array to investigate its membrane fouling potential. Advanced analytical methods including liquid chromatography with online carbon detection (LC-OCD) and fluorescent excitation-emission matrix (F-EEM) were employed for EfOM characterization. EfOM consisted of humic substances and building blocks, low molecular weight (LMW) neutrals, biopolymers (mainly proteins) and hydrophobic organics according to the sequence of their organic carbon fractions. The UF rejected only biopolymers and the NF rejected most humics and building blocks and a significant part of LMW neutrals. Simultaneous occurrence of cake layer and standard blocking during the filtration process of both UF and NF was identified according to constant-pressure filtration equations, which was possibly caused by the heterogeneous nature of EfOM with a wide MW distribution (several ten to several million Dalton). Thus the corresponding two fouling indices (kc for cake layer and ks for standard blocking) from UF and NF could characterize the fouling potential of macromolecular biopolymers and low to intermediate MW organics (including humics, building blocks, LMW neutrals), respectively. Compared with macromolecular biopolymers, low to intermediate MW organics exhibited a much higher fouling potential due to their lower molecular weight and higher concentration.

  16. Eccentricity samples: Implications on the potential and the velocity distribution

    Directory of Open Access Journals (Sweden)

    Cubarsi R.

    2017-01-01

    Full Text Available Planar and vertical epicycle frequencies and local angular velocity are related to the derivatives up to the second order of the local potential and can be used to test the shape of the potential from stellar disc samples. These samples show a more complex velocity distribution than halo stars and should provide a more realistic test. We assume an axisymmetric potential allowing a mixture of independent ellipsoidal velocity distributions, of separable or Staeckel form in cylindrical or spherical coordinates. We prove that values of local constants are not consistent with a potential separable in addition in cylindrical coordinates and with a spherically symmetric potential. The simplest potential that fits the local constants is used to show that the harmonical and non-harmonical terms of the potential are equally important. The same analysis is used to estimate the local constants. Two families of nested subsamples selected for decreasing planar and vertical eccentricities are used to borne out the relation between the mean squared planar and vertical eccentricities and the velocity dispersions of the subsamples. According to the first-order epicycle model, the radial and vertical velocity components provide accurate information on the planar and vertical epicycle frequencies. However, it is impossible to account for the asymmetric drift which introduces a systematic bias in estimation of the third constant. Under a more general model, when the asymmetric drift is taken into account, the rotation velocity dispersions together with their asymmetric drift provide the correct fit for the local angular velocity. The consistency of the results shows that this new method based on the distribution of eccentricities is worth using for kinematic stellar samples. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. No 176011: Dynamics and Kinematics of Celestial Bodies and Systems

  17. Changes in the Sterol Composition of the Plasma Membrane Affect Membrane Potential, Salt Tolerance and the Activity of Multidrug Resistance Pumps in Saccharomyces cerevisiae

    Czech Academy of Sciences Publication Activity Database

    Kodedová, Marie; Sychrová, Hana

    2015-01-01

    Roč. 10, č. 9 (2015), e0139306 E-ISSN 1932-6203 R&D Projects: GA MŠk(CZ) EE2.3.30.0025; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : Saccharomyces cerevisiae * ergosterol synthesis * multidrug resistance * membrane potential * diS-C3(3) assay Subject RIV: EE - Microbiology, Virology Impact factor: 3.057, year: 2015

  18. Yeast Kch1 and Kch2 membrane proteins play a pleiotropic role in membrane potential establishment and monovalent cation homeostasis regulation

    Czech Academy of Sciences Publication Activity Database

    Felcmanová, Kristina; Nevečeřalová, Petra; Sychrová, Hana; Zimmermannová, Olga

    2017-01-01

    Roč. 17, č. 5 (2017), č. článku fox053. ISSN 1567-1356 R&D Projects: GA ČR(CZ) GA16-03398S; GA MŠk(CZ) LH14297 Institutional support: RVO:67985823 Keywords : Kch proteins * plasma-membrane potential * monovalent cation homeostasis * intracellular pH * Saccharomyces cerevisiae * Candida albicans Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Mycology Impact factor: 3.299, year: 2016

  19. Saturation wind power potential and its implications for wind energy.

    Science.gov (United States)

    Jacobson, Mark Z; Archer, Cristina L

    2012-09-25

    Wind turbines convert kinetic to electrical energy, which returns to the atmosphere as heat to regenerate some potential and kinetic energy. As the number of wind turbines increases over large geographic regions, power extraction first increases linearly, but then converges to a saturation potential not identified previously from physical principles or turbine properties. These saturation potentials are >250 terawatts (TW) at 100 m globally, approximately 80 TW at 100 m over land plus coastal ocean outside Antarctica, and approximately 380 TW at 10 km in the jet streams. Thus, there is no fundamental barrier to obtaining half (approximately 5.75 TW) or several times the world's all-purpose power from wind in a 2030 clean-energy economy.

  20. Listeria Occurrence in Poultry Flocks: Detection and Potential Implications

    Science.gov (United States)

    Foodborne pathogens such as Salmonella, Campylobacter, Escherichia coli, and Listeria are a major concern within the food industry due to their pathogenic potential to cause infection. Of these, Listeria monocytogenes, possesses a high mortality rate (approximately20%) and is considered one of the m...

  1. Muskellunge growth potential in northern Wisconsin: implications for trophy management

    Science.gov (United States)

    Faust, Matthew D.; Isermann, Daniel A.; Luehring, Mark A.; Hansen, Michael J.

    2015-01-01

    The growth potential of Muskellunge Esox masquinongy was evaluated by back-calculating growth histories from cleithra removed from 305 fish collected during 1995–2011 to determine whether it was consistent with trophy management goals in northern Wisconsin. Female Muskellunge had a larger mean asymptotic length (49.8 in) than did males (43.4 in). Minimum ultimate size of female Muskellunge (45.0 in) equaled the 45.0-in minimum length limit, but was less than the 50.0-in minimum length limit used on Wisconsin's trophy waters, while the minimum ultimate size of male Muskellunge (34.0 in) was less than the statewide minimum length limit. Minimum reproductive sizes for both sexes were less than Wisconsin's trophy minimum length limits. Mean growth potential of female Muskellunge in northern Wisconsin appears to be sufficient for meeting trophy management objectives and angler expectations. Muskellunge in northern Wisconsin had similar growth potential to those in Ontario populations, but lower growth potential than Minnesota's populations, perhaps because of genetic and environmental differences.

  2. Mechanical properties of electrospun bilayer fibrous membranes as potential scaffolds for tissue engineering.

    Science.gov (United States)

    Pu, Juan; Komvopoulos, Kyriakos

    2014-06-01

    Bilayer fibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning, using a parallel-disk mandrel configuration that resulted in the sequential deposition of a layer with fibers aligned across the two parallel disks and a layer with randomly oriented fibers, both layers deposited in a single process step. Membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, bilayer membranes exhibited higher porosity than single-layer membranes consisting of randomly oriented fibers fabricated with a solid-drum collector. However, despite their higher porosity, bilayer membranes demonstrated generally higher elastic modulus, yield strength and toughness than single-layer membranes with random fibers. Bilayer membrane deformation at relatively high strain rates comprised multiple abrupt microfracture events characterized by discontinuous fiber breakage. Bilayer membrane elongation yielded excessive necking of the layer with random fibers and remarkable fiber stretching (on the order of 400%) in the layer with fibers aligned in the stress direction. In addition, fibers in both layers exhibited multiple localized necking, attributed to the nonuniform distribution of crystalline phases in the fibrillar structure. The high membrane porosity, good mechanical properties, and good biocompatibility and biodegradability of PLLA (demonstrated in previous studies) make the present bilayer membranes good scaffold candidates for a wide range of tissue engineering applications. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. NCAM180 regulates Ric8A membrane localization and potentiates β-adrenergic response.

    Directory of Open Access Journals (Sweden)

    Marie-Claude Amoureux

    Full Text Available Cooperation between receptors allows integrated intracellular signaling leading to appropriate physiological responses. The Neural Cell Adhesion Molecule (NCAM has three main isoforms of 120, 140 and 180 kDa, with adhesive and signaling properties, but their respective functions remains to be fully identified. Here we show that the human NCAM180 intracellular domain is a novel interactor of the human guanosine exchange factor (GEF Ric8A using the yeast two hybrid system and immunoprecipitation. Furthermore, NCAM, Ric8A and G(αs form a tripartite complex. Colocalization experiments by confocal microscopy revealed that human NCAM180 specifically induces the recruitment of Ric8A to the membrane. In addition, using an in vitro recombinant system, and in vivo by comparing NCAM knock-out mouse brain to NCAM heterozygous and wild type brains, we show that NCAM expression dose dependently regulates Ric8A redistribution in detergent resistent membrane microdomains (DRM. Previous studies have demonstrated essential roles for Ric8 in G(α protein activity at G protein coupled receptors (GPCR, during neurotransmitter release and for asymmetric cell division. We observed that inhibition of Ric8A by siRNA or its overexpression, decreases or increases respectively, cAMP production following β-adrenergic receptor stimulation. Furthermore, in human HEK293T recombinant cells, NCAM180 potentiates the G(αs coupled β-adrenergic receptor response, in a Ric8A dependent manner, whereas NCAM120 or NCAM140 do not. Finally, in mouse hippocampal neurons expressing endogenously NCAM, NCAM is required for the agonist isoproterenol to induce cAMP production, and this requirement depends on Ric8A. These data illustrate a functional crosstalk between a GPCR and an IgCAM in the nervous system.

  4. Levetiracetam differentially alters CD95 expression of neuronal cells and the mitochondrial membrane potential of immune and neuronal cells in vitro

    Directory of Open Access Journals (Sweden)

    Susannah K Rogers

    2014-02-01

    Full Text Available Epilepsy is a neurological seizure disorder that affects over 100 million people worldwide. Levetiracetam, either alone, as monotherapy, or as adjunctive treatment, is widely used to control certain types of seizures. Despite its increasing popularity as a relatively safe and effective anti-convulsive treatment option, its mechanism(s of action are poorly understood. Studies have suggested neuronal, glial, and immune mechanisms of action. Understanding the precise mechanisms of action of Levetiracetam would be extremely beneficial in helping to understand the processes involved in seizure generation and epilepsy. Moreover, a full understanding of these mechanisms would help to create more efficacious treatments while minimizing side effects. The current study examined the effects of Levetiracetam on the mitochondrial membrane potential of neuronal and non-neuronal cells, in vitro, in order to determine if Levetiracetam influences metabolic processes in these cell types. In addition, this study sought to address possible immune-mediated mechanisms by determining if Levetiracetam alters the expression of immune receptor-ligand pairs. The results show that Levetiracetam induces expression of CD95 and CD178 on NGF-treated C17.2 neuronal cells. The results also show that Levetiracetam increases mitochondrial membrane potential on C17.2 neuronal cells in the presence of nerve growth factor. In contrast, Levetiracetam decreases the mitochondrial membrane potential of splenocytes and this effect was dependent on intact invariant chain, thus implicating immune cell interactions. These results suggest that both neuronal and non-neuronal anti-epileptic activities of Levetiracetam involve control over energy metabolism, more specifically, mΔΨ. Future studies are needed to further investigate this potential mechanism of action.

  5. Reduction of low potential electron acceptors requires the CbcL inner membrane cytochrome of Geobacter sulfurreducens.

    Science.gov (United States)

    Zacharoff, Lori; Chan, Chi Ho; Bond, Daniel R

    2016-02-01

    The respiration of metals by the bacterium Geobacter sulfurreducens requires electrons generated by metabolism to pass from the interior of the cell to electron acceptors beyond the cell membranes. The G. sulfurreducens inner membrane multiheme c-type cytochrome ImcH is required for respiration to extracellular electron acceptors with redox potentials greater than -0.1 V vs. SHE, but ImcH is not essential for electron transfer to lower potential acceptors. In contrast, deletion of cbcL, encoding an inner membrane protein consisting of b-type and multiheme c-type cytochrome domains, severely affected reduction of low potential electron acceptors such as Fe(III)-oxides and electrodes poised at -0.1 V vs. SHE. Catalytic cyclic voltammetry of a ΔcbcL strain growing on poised electrodes revealed a 50 mV positive shift in driving force required for electron transfer out of the cell. In non-catalytic conditions, low-potential peaks present in wild type biofilms were absent in ∆cbcL mutants. Expression of cbcL in trans increased growth at low redox potential and restored features to cyclic voltammetry. This evidence supports a model where CbcL is a component of a second electron transfer pathway out of the G. sulfurreducens inner membrane that dominates when redox potential is at or below -0.1 V vs. SHE. Copyright © 2015. Published by Elsevier B.V.

  6. Listeria Occurrence in Poultry Flocks: Detection and Potential Implications

    Directory of Open Access Journals (Sweden)

    Michael J. Rothrock

    2017-08-01

    Full Text Available Foodborne pathogens such as Salmonella, Campylobacter, Escherichia coli, and Listeria are a major concern within the food industry due to their pathogenic potential to cause infection. Of these, Listeria monocytogenes, possesses a high mortality rate (approximately 20% and is considered one of the most dangerous foodborne pathogens. Although the usual reservoirs for Listeria transmission have been extensively studied, little is known about the relationship between Listeria and live poultry production. Sporadic and isolated cases of listeriosis have been attributed to poultry production and Listeria spp. have been isolated from all stages of poultry production and processing. Farm studies suggest that live birds may be an important vector and contributor to contamination of the processing environment and transmission of Listeria to consumers. Therefore, the purpose of this review is to highlight the occurrence, incidence, and potential systemic interactions of Listeria spp. with poultry.

  7. Vimentin is involved in regulation of mitochondrial motility and membrane potential by Rac1

    Directory of Open Access Journals (Sweden)

    Elena A. Matveeva

    2015-10-01

    Full Text Available In this study we show that binding of mitochondria to vimentin intermediate filaments (VIF is regulated by GTPase Rac1. The activation of Rac1 leads to a redoubling of mitochondrial motility in murine fibroblasts. Using double-mutants Rac1(G12V, F37L and Rac1(G12V, Y40H that are capable to activate different effectors of Rac1, we show that mitochondrial movements are regulated through PAK1 kinase. The involvement of PAK1 kinase is also confirmed by the fact that expression of its auto inhibitory domain (PID blocks the effect of activated Rac1 on mitochondrial motility. The observed effect of Rac1 and PAK1 kinase on mitochondria depends on phosphorylation of the Ser-55 of vimentin. Besides the effect on motility Rac1 activation also decreases the mitochondrial membrane potential (MMP which is detected by ∼20% drop of the fluorescence intensity of mitochondria stained with the potential sensitive dye TMRM. One of important consequences of the discovered regulation of MMP by Rac1 and PAK1 is a spatial differentiation of mitochondria in polarized fibroblasts: at the front of the cell they are less energized (by ∼25% than at the rear part.

  8. Dimethyl sulfoxide damages mitochondrial integrity and membrane potential in cultured astrocytes.

    Directory of Open Access Journals (Sweden)

    Chan Yuan

    Full Text Available Dimethyl sulfoxide (DMSO is a polar organic solvent that is used to dissolve neuroprotective or neurotoxic agents in neuroscience research. However, DMSO itself also has pharmacological and pathological effects on the nervous system. Astrocytes play a central role in maintaining brain homeostasis, but the effect and mechanism of DMSO on astrocytes has not been studied. The present study showed that exposure of astrocyte cultures to 1% DMSO for 24 h did not significantly affect cell survival, but decreased cell viability and glial glutamate transporter expression, and caused mitochondrial swelling, membrane potential impairment and reactive oxygen species production, and subsequent cytochrome c release and caspase-3 activation. DMSO at concentrations of 5% significantly inhibited cell variability and promoted apoptosis of astrocytes, accompanied with more severe mitochondrial damage. These results suggest that mitochondrial impairment is a primary event in DMSO-induced astrocyte toxicity. The potential cytotoxic effects on astrocytes need to be carefully considered during investigating neuroprotective or neurotoxic effects of hydrophobic agents dissolved by DMSO.

  9. Analysis of flux reduction behaviors of PRO hollow fiber membranes: Experiments, mechanisms, and implications

    KAUST Repository

    Xiong, Jun Ying

    2016-01-15

    Pressure retarded osmosis (PRO) is a promising technology to harvest renewable osmotic energy using a semipermeable membrane. However, a significant flux reduction has been always observed that severely shrinks the harvestable power to a level only marginally higher or even lower than the economically feasible value. This work focuses on the elucidation of various underlying mechanisms responsible for the flux reduction. First, both inner-selective and outer-selective thin film composite (TFC) hollow fiber membranes are employed to examine how the fundamental internal factors (such as the surface salinity of the selective layer at the feed side (CF,m) and its components) interact with one another under the fixed bulk salinity gradient, resulting in various behaviours of external performance indexes such as water flux, reverse salt flux, and power density. Then, the research is extended to investigate the effects of the growing bulk feed salinity due to the accumulated reverse salt flux along PRO modules. Finally, the insights obtained from the prior two stationary conditions are combined with the advanced nucleation theory to elucidate the dynamic scaling process by visualizing how the multiple fundamental factors (such as local supersaturation, nucleation rate and nuclei size) evolve and interplay with one another in various membrane regimes during the whole scaling process. To our best knowledge, it is the first time that the advanced nucleation theory is applied to study the PRO scaling kinetics in order to provide subtle and clear pictures of the events occurring inside the membrane. This study may provide useful insights to design more suitable TFC hollow fiber membranes and to operate them with enhanced water flux so that the PRO process may become more promising in the near future.

  10. Implication of Heat Shock Factors in Tumorigenesis: Therapeutical Potential

    Energy Technology Data Exchange (ETDEWEB)

    Thonel, Aurelie de [INSERM U866, Dijon (France); Faculty of Medicine and Pharmacy, University of Burgundy, 21033 Dijon (France); Mezger, Valerie, E-mail: valerie.mezger@univ-paris-diderot.fr [CNRS, UMR7216 Epigenetics and Cell Fate, Paris (France); University Paris Diderot, 75013 Paris (France); Garrido, Carmen, E-mail: valerie.mezger@univ-paris-diderot.fr [INSERM U866, Dijon (France); Faculty of Medicine and Pharmacy, University of Burgundy, 21033 Dijon (France); CHU, Dijon BP1542, Dijon (France)

    2011-03-07

    Heat Shock Factors (HSF) form a family of transcription factors (four in mammals) which were named according to the discovery of their activation by a heat shock. HSFs trigger the expression of genes encoding Heat Shock Proteins (HSPs) that function as molecular chaperones, contributing to establish a cytoprotective state to various proteotoxic stresses and in pathological conditions. Increasing evidence indicates that this ancient transcriptional protective program acts genome-widely and performs unexpected functions in the absence of experimentally defined stress. Indeed, HSFs are able to re-shape cellular pathways controlling longevity, growth, metabolism and development. The most well studied HSF, HSF1, has been found at elevated levels in tumors with high metastatic potential and is associated with poor prognosis. This is partly explained by the above-mentioned cytoprotective (HSP-dependent) function that may enable cancer cells to adapt to the initial oncogenic stress and to support malignant transformation. Nevertheless, HSF1 operates as major multifaceted enhancers of tumorigenesis through, not only the induction of classical heat shock genes, but also of “non-classical” targets. Indeed, in cancer cells, HSF1 regulates genes involved in core cellular functions including proliferation, survival, migration, protein synthesis, signal transduction, and glucose metabolism, making HSF1 a very attractive target in cancer therapy. In this review, we describe the different physiological roles of HSFs as well as the recent discoveries in term of non-cogenic potential of these HSFs, more specifically associated to the activation of “non-classical” HSF target genes. We also present an update on the compounds with potent HSF1-modulating activity of potential interest as anti-cancer therapeutic agents.

  11. Role of the Na+/K+-ATPase in regulating the membrane potential in rat peritoneal mast cells

    DEFF Research Database (Denmark)

    Friis, U G; Praetorius, Birger Hans; Knudsen, T

    1997-01-01

    of Sylgard-coated patch pipettes (3-6 M[omega]). High-resolution membrane currents were recorded with an EPC-9 patch-clamp amplifier controlled by the 'E9SCREEN' software. In addition, a charting programme on another computer synchronously recorded at low resolution (2 Hz) membrane potential and holding...... current (low-pass filtered at 500 Hz). 3. Na+/K+-ATPase activity was measured as the ouabain-sensitive change in the zero-current potential. The zero-current potential in rat peritoneal mast cells measured 2 min after obtaining whole-cell configuration amounted to 1.7 +/- 2.5 mV (n = 21). Ouabain (5 m...... preincubated in nominal calcium-free external solution for 12 +/- 1.6 min before whole-cell configuration, the membrane potential amounted to -53.7 +/- 9.8 mV (n = 8). A subsequent superfusion with ouabain (5 mM) depolarized the membrane potential (ouabain-sensitive hyperpolarization (delta mV): 23.0 +/- 8.4 m...

  12. Sensory transduction at the frog semicircular canal: how hair cell membrane potential controls junctional transmission

    Science.gov (United States)

    Martini, Marta; Canella, Rita; Rubbini, Gemma; Fesce, Riccardo; Rossi, Maria Lisa

    2015-01-01

    At the frog semicircular canals, the afferent fibers display high spontaneous activity (mEPSPs), due to transmitter release from hair cells. mEPSP and spike frequencies are modulated by stimulation that activates the hair cell receptor conductance. The relation between receptor current and transmitter release cannot be studied at the intact semicircular canal. To circumvent the problem, we combined patch-clamp recordings at the isolated hair cell and electrophysiological recordings at the cytoneural junction in the intact preparation. At isolated hair cells, the K channel blocker tetraethylammonium (TEA) is shown to block a fraction of total voltage-dependent K-conductance (IKD) that depends on TEA concentration but not on membrane potential (Vm). Considering the bioelectric properties of the hair cell, as previously characterized by this lab, a fixed fractional block of IKD is shown to induce a relatively fixed shift in Vm, provided it lies in the range −30 to −10 mV. The same concentrations of TEA were applied to the intact labyrinth while recording from single afferent fibers of the posterior canal, at rest and during mechanical stimulation. At the peak of stimulation, TEA produced increases in mEPSP rate that were linearly related to the shifts produced by the same TEA concentrations (0.1–3 mM) in hair cell Vm (0.7–5 mV), with a slope of 29.8 Hz/mV. The membrane potential of the hair cell is not linearly related to receptor conductance, so that the slope of quantal release vs. receptor conductance depends on the prevailing Vm (19.8 Hz/nS at −20 mV; 11 Hz/nS at −10 mV). Changes in mEPSP peak size were negligible at rest as well as during stimulation. Since ample spatial summation of mEPSPs occurs at the afferent terminal and threshold-governed spike firing is intrinsically nonlinear, the observed increases in mEPSP frequency, though not very large, may suffice to trigger afferent spike discharge. PMID:26157360

  13. Mesenchymal stem cells with osteogenic potential in human maxillary sinus membrane: an in vitro study.

    Science.gov (United States)

    Berbéri, Antoine; Al-Nemer, Fatima; Hamade, Eva; Noujeim, Ziad; Badran, Bassam; Zibara, Kazem

    2017-06-01

    The aim of our study is to prove and validate the existence of an osteogenic progenitor cell population within the human maxillary Schneiderian sinus membrane (hMSSM) and to demonstrate their potential for bone formation. Ten hMSSM samples of approximately 2 × 2 cm were obtained during a surgical nasal approach for treatment of chronic rhinosinusitis and were retained for this study. The derived cells were isolated, cultured, and assayed at passage 3 for their osteogenic potential using the expression of Alkaline phosphatase, alizarin red and Von Kossa staining, flow cytometry, and quantitative real-time polymerase chain reaction. hMSSM-derived cells were isolated, showed homogenous spindle-shaped fibroblast-like morphology, characteristic of mesenchymal progenitor cells (MPCs), and demonstrated very high expression of MPC markers such as STRO-1, CD44, CD90, CD105, and CD73 in all tested passages. In addition, von Kossa and Alizarin red staining showed significant mineralization, a typical feature of osteoblasts. Moreover, alkaline phosphatase (ALP) activity was significantly increased at days 7, 14, 21, and 28 of culture in hMSSM-derived cells grown in osteogenic medium, in comparison to controls. Furthermore, osteogenic differentiation significantly upregulated the transcriptional expression of osteogenic markers such as ALP, Runt-related transcription factor 2 (Runx-2), bone morphogenetic protein (BMP)-2, osteocalcin (OCN), osteonectin (ON), and osteopontin (OPN), confirming that hMSSM-derived cells are of osteoprogenitor origin. Finally, hMSSM-derived cells were also capable of producing OPN proteins upon culturing in an osteogenic medium. Our data showed that hMSSM holds mesenchymal osteoprogenitor cells capable of differentiating to the osteogenic lineage. hMSSM contains potentially multipotent postnatal stem cells providing a promising clinical application in preimplant and implant therapy.

  14. Recent decrease in typhoon destructive potential and global warming implications

    Science.gov (United States)

    Lin, I.-I.; Chan, Johnny C. L.

    2015-05-01

    Typhoons (tropical cyclones) severely impact the half-billion population of the Asian Pacific. Intriguingly, during the recent decade, typhoon destructive potential (Power Dissipation Index, PDI) has decreased considerably (by ~35%). This decrease, paradoxically, has occurred despite the increase in typhoon intensity and ocean warming. Using the method proposed by Emanuel (in 2007), we show that the stronger negative contributions from typhoon frequency and duration, decrease to cancel the positive contribution from the increasing intensity, controlling the PDI. Examining the typhoons' environmental conditions, we find that although the ocean condition became more favourable (warming) in the recent decade, the atmospheric condition `worsened' at the same time. The `worsened' atmospheric condition appears to effectively overpower the `better' ocean conditions to suppress PDI. This stronger negative contribution from reduced typhoon frequency over the increased intensity is also present under the global warming scenario, based on analysis of the simulated typhoon data from high-resolution modelling.

  15. The human gut microbiota and virome: Potential therapeutic implications.

    Science.gov (United States)

    Scarpellini, Emidio; Ianiro, Gianluca; Attili, Fabia; Bassanelli, Chiara; De Santis, Adriano; Gasbarrini, Antonio

    2015-12-01

    Human gut microbiota is a complex ecosystem with several functions integrated in the host organism (metabolic, immune, nutrients absorption, etc.). Human microbiota is composed by bacteria, yeasts, fungi and, last but not least, viruses, whose composition has not been completely described. According to previous evidence on pathogenic viruses, the human gut harbours plant-derived viruses, giant viruses and, only recently, abundant bacteriophages. New metagenomic methods have allowed to reconstitute entire viral genomes from the genetic material spread in the human gut, opening new perspectives on the understanding of the gut virome composition, the importance of gut microbiome, and potential clinical applications. This review reports the latest evidence on human gut "virome" composition and its function, possible future therapeutic applications in human health in the context of the gut microbiota, and attempts to clarify the role of the gut "virome" in the larger microbial ecosystem. Copyright © 2015 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  16. Potential implications of climate change and urbanization on watershed hydrology

    Science.gov (United States)

    Pumo, D.; Arnone, E.; Francipane, A.; Caracciolo, D.; Noto, L. V.

    2017-11-01

    This paper proposes a modeling framework able to analyze the alterations in watershed hydrology induced by two recurrent drivers for hydrological changes: climate change and urbanization. The procedure is based on the coupling of a stochastic weather generator with a land use change model for the generation of some hypothetical scenarios. The generated scenarios are successively used to force a physically-based and spatial distributed hydrological model to reconstruct the basin response under different conditions. Several potential climate alterations are simulated by imposing negative and positive variations in the mean annual precipitation and a simultaneous temperature increase. Urbanization is conceptualized by an increase in the impervious fraction of the basin. The procedure is applied to a large basin and a much smaller sub-basin; the results show how climate and land use changes may interact and affect the fundamental hydrological dynamics and how the processes governing basin hydrological response may change with spatial scale.

  17. [Focus on the Immunoscore and its potential clinical implications].

    Science.gov (United States)

    El Sissy, Carine; Marliot, Florence; Haicheur, Nacilla; Kirilovsky, Amos; Scripcariu, Dragos; Lagorce-Pagès, Christine; Galon, Jérôme; Pagès, Franck

    2017-02-01

    The role of the immune response at the tumor site is now recognized as crucial in the clinical course of patients with cancer. The importance of the immune cell type, their functional orientation, their density and location within the tumor's regions (tumor/invasion margin) has recently been shown and were grouped together under the term "immune contexture". A strong infiltration by cytotoxic and memory T cells in a Th1-polarized tumor microenvironment appears to have a major prognosis impact. A test called Immunoscore taking into account these various parameters has been suggested to measure in a simple, reproducible and robust manner the intra- and peritumoral immune response. The prognostic value of Immunoscore has recently been validated in colon cancers by a large international retrospective study under the aegis of the Society for Immunotherapy of Cancer (SITC). The Immunoscore could have several potential clinical applications such as prognostic as well as theranostic. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  18. Recent decrease in typhoon destructive potential and global warming implications

    Science.gov (United States)

    Lin, I-I; Chan, Johnny C.L.

    2015-01-01

    Typhoons (tropical cyclones) severely impact the half-billion population of the Asian Pacific. Intriguingly, during the recent decade, typhoon destructive potential (Power Dissipation Index, PDI) has decreased considerably (by ∼35%). This decrease, paradoxically, has occurred despite the increase in typhoon intensity and ocean warming. Using the method proposed by Emanuel (in 2007), we show that the stronger negative contributions from typhoon frequency and duration, decrease to cancel the positive contribution from the increasing intensity, controlling the PDI. Examining the typhoons' environmental conditions, we find that although the ocean condition became more favourable (warming) in the recent decade, the atmospheric condition ‘worsened' at the same time. The ‘worsened' atmospheric condition appears to effectively overpower the ‘better' ocean conditions to suppress PDI. This stronger negative contribution from reduced typhoon frequency over the increased intensity is also present under the global warming scenario, based on analysis of the simulated typhoon data from high-resolution modelling. PMID:25990561

  19. Configuration and technology implications of potential nuclear hydrogen system applications.

    Energy Technology Data Exchange (ETDEWEB)

    Conzelmann, G.; Petri, M.; Forsberg, C.; Yildiz, B.; ORNL

    2005-11-05

    Nuclear technologies have important distinctions and potential advantages for large-scale generation of hydrogen for U.S. energy services. Nuclear hydrogen requires no imported fossil fuels, results in lower greenhouse-gas emissions and other pollutants, lends itself to large-scale production, and is sustainable. The technical uncertainties in nuclear hydrogen processes and the reactor technologies needed to enable these processes, as well waste, proliferation, and economic issues must be successfully addressed before nuclear energy can be a major contributor to the nation's energy future. In order to address technical issues in the time frame needed to provide optimized hydrogen production choices, the Nuclear Hydrogen Initiative (NHI) must examine a wide range of new technologies, make the best use of research funding, and make early decisions on which technology options to pursue. For these reasons, it is important that system integration studies be performed to help guide the decisions made in the NHI. In framing the scope of system integration analyses, there is a hierarchy of questions that should be addressed: What hydrogen markets will exist and what are their characteristics? Which markets are most consistent with nuclear hydrogen? What nuclear power and production process configurations are optimal? What requirements are placed on the nuclear hydrogen system? The intent of the NHI system studies is to gain a better understanding of nuclear power's potential role in a hydrogen economy and what hydrogen production technologies show the most promise. This work couples with system studies sponsored by DOE-EE and other agencies that provide a basis for evaluating and selecting future hydrogen production technologies. This assessment includes identifying commercial hydrogen applications and their requirements, comparing the characteristics of nuclear hydrogen systems to those market requirements, evaluating nuclear hydrogen configuration options

  20. Potentials and policy implications of energy and material efficiency improvement

    Energy Technology Data Exchange (ETDEWEB)

    Worrell, Ernst; Levine, Mark; Price, Lynn; Martin, Nathan; van den Broek, Richard; Block, Kornelis

    1997-01-01

    There is a growing awareness of the serious problems associated with the provision of sufficient energy to meet human needs and to fuel economic growth world-wide. This has pointed to the need for energy and material efficiency, which would reduce air, water and thermal pollution, as well as waste production. Increasing energy and material efficiency also have the benefits of increased employment, improved balance of imports and exports, increased security of energy supply, and adopting environmentally advantageous energy supply. A large potential exists for energy savings through energy and material efficiency improvements. Technologies are not now, nor will they be, in the foreseeable future, the limiting factors with regard to continuing energy efficiency improvements. There are serious barriers to energy efficiency improvement, including unwillingness to invest, lack of available and accessible information, economic disincentives and organizational barriers. A wide range of policy instruments, as well as innovative approaches have been tried in some countries in order to achieve the desired energy efficiency approaches. These include: regulation and guidelines; economic instruments and incentives; voluntary agreements and actions, information, education and training; and research, development and demonstration. An area that requires particular attention is that of improved international co-operation to develop policy instruments and technologies to meet the needs of developing countries. Material efficiency has not received the attention that it deserves. Consequently, there is a dearth of data on the qualities and quantities for final consumption, thus, making it difficult to formulate policies. Available data, however, suggest that there is a large potential for improved use of many materials in industrialized countries.

  1. Optical coherence tomography: a potential tool to predict premature rupture of fetal membranes.

    Science.gov (United States)

    Micili, Serap C; Valter, Markus; Oflaz, Hakan; Ozogul, Candan; Linder, Peter; Föckler, Nicole; Artmann, Gerhard M; Digel, Ilya; Artmann, Aysegul T

    2013-04-01

    A fundamental question addressed in this study was the feasibility of preterm birth prediction based on a noncontact investigation of fetal membranes in situ. Although the phenomena of preterm birth and the premature rupture of the fetal membrane are well known, currently, there are no diagnostic tools for their prediction. The aim of this study was to assess whether optical coherence tomography could be used for clinical investigations of high-risk pregnancies. The thickness of fetal membranes was measured in parallel by optical coherence tomography and histological techniques for the following types of birth: normal births, preterm births without premature ruptures and births at full term with premature rupture of membrane. Our study revealed that the membrane thickness correlates with the birth type. Normal births membranes were statistically significantly thicker than those belonging to the other two groups. Thus, in spite of almost equal duration of gestation of the normal births and the births at full term with premature rupture, the corresponding membrane thicknesses differed. This difference is possibly related to previously reported water accumulation in the membranes. The optical coherence tomography results were encouraging, suggesting that this technology could be used in future to predict and distinguish between different kinds of births.

  2. Protein expression profiling of nuclear membrane protein reveals potential biomarker of human hepatocellular carcinoma

    OpenAIRE

    Khan, Rizma; Zahid, Saadia; Wan, Yu-Jui; Forster, Jameson; Karim, A-Bashar; Nawabi, Atta M; Azhar, Abid; Rahman, M; Ahmed, Nikhat

    2013-01-01

    Abstract Background Complex molecular events lead to development and progression of liver cirrhosis to HCC. Differentially expressed nuclear membrane associated proteins are responsible for the functional and structural alteration during the progression from cirrhosis to carcinoma. Although alterations/ post translational modifications in protein expression have been extensively quantified, complementary analysis of nuclear membrane proteome changes h...

  3. Potential Antidepressant Role of Neurotransmitter CART: Implications for Mental Disorders

    Directory of Open Access Journals (Sweden)

    Peizhong Mao

    2011-01-01

    Full Text Available Depression is one of the most prevalent and debilitating public health concerns. Although no single cause of depression has been identified, it appears that interaction among genetic, epigenetic, biochemical, environmental, and psychosocial factors may explain its etiology. Further, only a fraction of depressed patients show full remission while using current antidepressants. Therefore, identifying common pathways of the disorder and using that knowledge to develop more effective pharmacological treatments are two primary targets of research in this field. Brain-enriched neurotransmitter CART (cocaine- and amphetamine-regulated transcript has multiple functions related to emotions. It is a potential neurotrophic factor and is involved in the regulation of hypothalamic-pituitary-adrenal axis and stress response as well as in energy homeostasis. CART is also highly expressed in limbic system, which is considered to have an important role in regulating mood. Notably, adolescents carrying a missense mutation in the CART gene exhibit increased depression and anxiety. Hence, CART peptide may be a novel promising antidepressant agent. In this paper, we summarize recent progress in depression and CART. In particular, we emphasize a new antidepressant function for CART.

  4. Embryonic–maternal cross-talk via exosomes: potential implications

    Directory of Open Access Journals (Sweden)

    Saadeldin IM

    2015-07-01

    Full Text Available Islam M Saadeldin,1 Hyun Ju Oh,2 Byeong Chun Lee2,3 1Department of Physiology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt; 2Department of Theriogenology and Biotechnology, College of Veterinary Medicine and the Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea; 3Institute of Green Bio Science and Technology, Seoul National University, Pyeong Chang, Kangwon do, Republic of KoreaAbstract: A myriad of locally produced factors into the microenvironment of the reproductive tract is regulated, not one-way but rather, through embryonic–maternal cross-talk. In this minireview, we focused on the exosomes, which are cell-derived vesicles of 30–100 nm in diameter, as a communicating language facilitating this dialog. These nanovesicles are secreted from preimplantation embryos, oviduct epithelium, and endometrium as well as from the placenta, and contain proteins, messenger RNA (mRNA, microRNA, and DNA cargoes, and have pleiotropic effects on both embryonic and maternal environments. A better understanding of the molecular mechanisms mediating this cross-talk will lead to the development of new regulating agents, with novel diagnostic, biological, and therapeutic potential for either supporting or hindering the normal reproductive functions. Keywords: embryo, endometrium, placenta, mRNA, miRNA

  5. Ion channel regulation of the dynamical instability of the resting membrane potential in saccular hair cells of the green frog (Rana esculenta)

    NARCIS (Netherlands)

    Jorgensen, F; Kroese, ABA

    2005-01-01

    Aims: We investigated the ion channel regulation of the resting membrane potential of hair cells with the aim to determine if the resting membrane potential is poised close to instability and thereby a potential cause of the spontaneous afferent spike activity. Methods: The ionic mechanism and the

  6. Membrane potential dynamics of populations of cortical neurons during auditory streaming

    Science.gov (United States)

    Farley, Brandon J.

    2015-01-01

    How a mixture of acoustic sources is perceptually organized into discrete auditory objects remains unclear. One current hypothesis postulates that perceptual segregation of different sources is related to the spatiotemporal separation of cortical responses induced by each acoustic source or stream. In the present study, the dynamics of subthreshold membrane potential activity were measured across the entire tonotopic axis of the rodent primary auditory cortex during the auditory streaming paradigm using voltage-sensitive dye imaging. Consistent with the proposed hypothesis, we observed enhanced spatiotemporal segregation of cortical responses to alternating tone sequences as their frequency separation or presentation rate was increased, both manipulations known to promote stream segregation. However, across most streaming paradigm conditions tested, a substantial cortical region maintaining a response to both tones coexisted with more peripheral cortical regions responding more selectively to one of them. We propose that these coexisting subthreshold representation types could provide neural substrates to support the flexible switching between the integrated and segregated streaming percepts. PMID:26269558

  7. Carbon nanotubes on Jurkat cells: effects on cell viability and plasma membrane potential

    Science.gov (United States)

    DeNicola, Milena; Bellucci, Stefano; Traversa, Enrico; DeBellis, Giovanni; Micciulla, Federico; Ghibelli, Lina

    2008-11-01

    Carbon nanotubes (CNT) are one of the most novel attractive materials in nanotechnology for their potential multiple applications, including in the biomedical fields. The biocompatibility and toxicity of these novel nanomaterials are still largely unknown and a systematic study on biological interference is essential. We present a toxicological assessment of different types of CNT on the human tumor lymphocytic Jurkat cells. The carbon nanomaterials examined differ in preparation, size, contaminants and morphology: (1) CNT composed of MWCNT+SWCNT, with no metal contaminants; (2) MWCNT and (3) SWCNT, both with metal contaminants; (4) carbon black as control. The results indicate that CNT exert a dose- and time-dependent cytotoxic effect on Jurkat cells, inducing apoptotic cell death, accelerating the transition to secondary necrosis and increasing the extent of apoptosis induced by damaging agents; interestingly, CNT induce a plasma membrane hyperpolarization. These alterations are produced by all types of CNT, but contaminants and/or the size modulate the extent of such effects. Thus CNT deeply affect cell behavior, suggesting that they might play a role in inflammation, and recommending greater attention in terms of evaluation of exposure risks.

  8. Imaging membrane potential changes from dendritic spines using computer-generated holography.

    Science.gov (United States)

    Tanese, Dimitrii; Weng, Ju-Yun; Zampini, Valeria; De Sars, Vincent; Canepari, Marco; Rozsa, Balazs; Emiliani, Valentina; Zecevic, Dejan

    2017-07-01

    Electrical properties of neuronal processes are extraordinarily complex, dynamic, and, in the general case, impossible to predict in the absence of detailed measurements. To obtain such a measurement one would, ideally, like to be able to monitor electrical subthreshold events as they travel from synapses on distal dendrites and summate at particular locations to initiate action potentials. It is now possible to carry out these measurements at the scale of individual dendritic spines using voltage imaging. In these measurements, the voltage-sensitive probes can be thought of as transmembrane voltmeters with a linear scale, which directly monitor electrical signals. Grinvald et al. were important early contributors to the methodology of voltage imaging, and they pioneered some of its significant results. We combined voltage imaging and glutamate uncaging using computer-generated holography. The results demonstrated that patterned illumination, by reducing the surface area of illuminated membrane, reduces photodynamic damage. Additionally, region-specific illumination practically eliminated the contamination of optical signals from individual spines by the scattered light from the parent dendrite. Finally, patterned illumination allowed one-photon uncaging of glutamate on multiple spines to be carried out in parallel with voltage imaging from the parent dendrite and neighboring spines.

  9. Mechanisms of generation of membrane potential resonance in a neuron with multiple resonant ionic currents.

    Directory of Open Access Journals (Sweden)

    David M Fox

    2017-06-01

    Full Text Available Neuronal membrane potential resonance (MPR is associated with subthreshold and network oscillations. A number of voltage-gated ionic currents can contribute to the generation or amplification of MPR, but how the interaction of these currents with linear currents contributes to MPR is not well understood. We explored this in the pacemaker PD neurons of the crab pyloric network. The PD neuron MPR is sensitive to blockers of H- (IH and calcium-currents (ICa. We used the impedance profile of the biological PD neuron, measured in voltage clamp, to constrain parameter values of a conductance-based model using a genetic algorithm and obtained many optimal parameter combinations. Unlike most cases of MPR, in these optimal models, the values of resonant- (fres and phasonant- (fϕ = 0 frequencies were almost identical. Taking advantage of this fact, we linked the peak phase of ionic currents to their amplitude, in order to provide a mechanistic explanation the dependence of MPR on the ICa gating variable time constants. Additionally, we found that distinct pairwise correlations between ICa parameters contributed to the maintenance of fres and resonance power (QZ. Measurements of the PD neuron MPR at more hyperpolarized voltages resulted in a reduction of fres but no change in QZ. Constraining the optimal models using these data unmasked a positive correlation between the maximal conductances of IH and ICa. Thus, although IH is not necessary for MPR in this neuron type, it contributes indirectly by constraining the parameters of ICa.

  10. Carbon nanotubes on Jurkat cells: effects on cell viability and plasma membrane potential

    International Nuclear Information System (INIS)

    De Nicola, Milena; Ghibelli, Lina; Bellucci, Stefano; Bellis, Giovanni De; Micciulla, Federico; Traversa, Enrico

    2008-01-01

    Carbon nanotubes (CNT) are one of the most novel attractive materials in nanotechnology for their potential multiple applications, including in the biomedical fields. The biocompatibility and toxicity of these novel nanomaterials are still largely unknown and a systematic study on biological interference is essential. We present a toxicological assessment of different types of CNT on the human tumor lymphocytic Jurkat cells. The carbon nanomaterials examined differ in preparation, size, contaminants and morphology: (1) CNT composed of MWCNT+SWCNT, with no metal contaminants; (2) MWCNT and (3) SWCNT, both with metal contaminants; (4) carbon black as control. The results indicate that CNT exert a dose- and time-dependent cytotoxic effect on Jurkat cells, inducing apoptotic cell death, accelerating the transition to secondary necrosis and increasing the extent of apoptosis induced by damaging agents; interestingly, CNT induce a plasma membrane hyperpolarization. These alterations are produced by all types of CNT, but contaminants and/or the size modulate the extent of such effects. Thus CNT deeply affect cell behavior, suggesting that they might play a role in inflammation, and recommending greater attention in terms of evaluation of exposure risks.

  11. Generation of the membrane potential and its impact on the motility, ATP production and growth in Campylobacter jejuni

    Science.gov (United States)

    The generation of an electrical membrane potential (''), the major constituent of the proton motive force (pmf) is crucial for the ATP synthesis, bacterial growth and motility. The pmf drives the rotation of flagella and is vital for the microaerophilic human pathogen Campylobacter jejuni to coloniz...

  12. Mitochondrial membrane potential in human neutrophils is maintained by complex III activity in the absence of supercomplex organisation

    NARCIS (Netherlands)

    van Raam, Bram J.; Sluiter, Wim; de Wit, Elly; Roos, Dirk; Verhoeven, Arthur J.; Kuijpers, Taco W.

    2008-01-01

    BACKGROUND: Neutrophils depend mainly on glycolysis for their energy provision. Their mitochondria maintain a membrane potential (Deltapsi(m)), which is usually generated by the respiratory chain complexes. We investigated the source of Deltapsi(m) in neutrophils, as compared to peripheral blood

  13. Na+/K(+)pump activity in photoreceptors of the blowfly Calliphora : A model analysis based on membrane potential measurements

    NARCIS (Netherlands)

    Gerster, U; Stavenga, DG; Backhaus, W

    Na+/K+-pump activity and intracellular Na+ and K+ concentration changes in blowfly photoreceptors are derived from intracellular potential measurements in vivo with a model based on the Goldman-Hodgkin-Katz theory for membrane currents. The relation between the intracellular Na+ concentration and

  14. Carnosic acid is an efflux pumps modulator by dissipation of the membrane potential in Enterococcus faecalis and Staphylococcus aureus.

    Science.gov (United States)

    Ojeda-Sana, Adriana M; Repetto, Victoria; Moreno, Silvia

    2013-01-01

    Bacterial resistance to antibiotics has become a serious problem of public health. Along with the controlled permeability by the cell-wall, active efflux systems can provide resistance by extruding antibiotics. Carnosic acid is capable to potentiate the antimicrobial activity of several antibiotics. However, the underlying molecular mechanism governing this effect remains unclear. The present study aims to investigate the effect of carnosic acid on the transport of ethidium bromide, on the permeability or the membrane potential in Enterococcus faecalis and Staphylococcus aureus. By using fluorimetric assays it was demonstrated that in E. faecalis, carnosic acid is a modulator of the uptake and efflux of ethidium bromide which does not induce cell membrane permeabilization phenomena. Such effect was sensitive to the inhibition caused by both the proton-motive force carbonyl cyanide m-chlorophenylhydrazone and the calcium antagonist verapamil, but not to vanadate, an ATPase inhibitor. In this work it was demonstrated, for the first time, that the activity of carnosic acid on the uptake/efflux of ethidium bromide is correlated with its capacity to change the membrane potential gradient in S. aureus and E. faecalis. In conclusion, carnosic acid is a natural compound, structurally unrelated to known antibiotics, which can function as an efflux pump modulator by dissipation of the membrane potential. Therefore, carnosic acid would be a good candidate to be employed as a novel therapeutic agent to be used in combination therapies against drug-resistant enterococci and S. aureus infections.

  15. Gender differences in susceptibility to schizophrenia: Potential implication of neurosteroids.

    Science.gov (United States)

    Huang, Yu-Chi; Hung, Chi-Fa; Lin, Pao-Yen; Lee, Yu; Wu, Chih-Ching; Hsu, Su-Ting; Chen, Chien-Chih; Chong, Mian-Yoon; Lin, Chieh-Hsin; Wang, Liang-Jen

    2017-10-01

    Past research has indicated gender differences in the clinical characteristics and course of schizophrenia. In this study, we investigated whether gender differences in the manifestation of schizophrenia are correlated with neurosteroids, including dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and pregnenolone. We further explored the potential relationship between the aforementioned neurosteroids and psychopathology. We recruited 65 schizophrenic patients (36 males and 29 females) and 103 healthy control subjects (47 males and 56 females) and obtained blood samples from the subjects in the morning while in a fasting state to determine the serum levels of DHEA, DHEA-S, and pregnenolone. The psychopathology and mood symptoms of patients with schizophrenia were evaluated using the Positive and Negative Syndrome Scale (PANSS) and 17-item Hamilton Depression Rating Scale, respectively. Compared to the male control subjects, male patients with schizophrenia had significantly lower serum levels of DHEA and pregnenolone. In males with schizophrenia, the serum levels of DHEA and DHEA-S were associated with the age of onset and the duration of illness, while pregnenolone levels were associated with general symptoms of the PANSS. However, none of the neurosteroid levels were different between the female patients with schizophrenia and the female controls, and no significant correlation between neurosteroid levels and psychopathology evaluations was found among the schizophrenic females. Neurosteroids, including DHEA, DHEA-S, and pregnenolone, are involved in the pathophysiology of schizophrenia in male patients, but not in female ones. Therefore, our findings suggest that neurosteroids may be associated with gender differences in susceptibility to schizophrenia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Electroresponsive properties and membrane potential trajectories of three types of inspiratory neurons in the newborn mouse brain stem in vitro

    DEFF Research Database (Denmark)

    Rekling, J C; Champagnat, J; Denavit-Saubié, M

    1996-01-01

    with a resting membrane potential of -48.6 +/- 10.1 mV and an input resistance of 306 +/- 130 M omega (n = 15). The spike activity between the inspiratory potentials was burst-like with spikes riding on top of an underlying depolarization (n = 11) or regular with no evidence of bursting (n = 12...... between the inspiratory potentials with no evidence of bursting behavior and had an input resistance of 296 +/- 212 M omega (n = 26). The response to hyperpolarizing pulses revealed an initial sag and postinhibitory rebound depolarization. This membrane behavior resembles the response seen in other CNS...... neurons expressing an Ih. The Vm-I relationship was linear at depolarized potentials and showed a marked upward rectification below -60 mV. Spike trains elicited by 1-s long pulses showed a pronounced early and late adaptation. 7. Type-2 neurons depolarized and started to fire spikes 171 +/- 87 ms (n = 23...

  17. The chorioallantoic membrane test as a model to predict the potential human eye irritation induced by commonly used laboratory solvents.

    Science.gov (United States)

    Vinardell, M P; Mitjans, M

    2006-09-01

    The purpose of this study was to investigate the potential eye irritation of a range of solvents, extensively used in industry and laboratory and the capacity of the chorioallantoic membrane test to predict this eye irritation. The irritation has been evaluated by an in vitro method using the chorioallantoic membrane as an alternative to in vivo Draize rabbit test. All the solvents studied are potentially strongly irritants, even though diluted, except dimethyl sulfoxide which was moderately irritant at a concentration of 10% v/v. In some cases there is a correlation between the concentration of the solvent and the potential eye irritation induced. The method allows prediction of the potential eye irritation of the solvents studied.

  18. Automated food microbiology: potential for the hydrophobic grid-membrane filter.

    Science.gov (United States)

    Sharpe, A N; Diotte, M P; Dudas, I; Michaud, G L

    1978-07-01

    Bacterial counts obtained on hydrophobic grid-membrane filters were comparable to conventional plate counts for Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus in homogenates from a range of foods. The wide numerical operating range of the hydrophobic grid-membrane filters allowed sequential diluting to be reduced or even eliminated, making them attractive as components in automated systems of analysis. Food debris could be rinsed completely from the unincubated hydrophobic grid-membrane filter surface without affecting the subsequent count, thus eliminating the possibility of counting food particles, a common source of error in electronic counting systems.

  19. Intracervical fibrin sealants: a potential treatment for early preterm premature rupture of the membranes.

    Science.gov (United States)

    Sciscione, A C; Manley, J S; Pollock, M; Maas, B; Shlossman, P A; Mulla, W; Lankiewicz, M; Colmorgen, G H

    2001-02-01

    We report our experience with a transvaginally applied intracervical fibrin sealant at <24 weeks' gestation. This is an observational study of a referred patient population, with preterm premature rupture of the membranes at <24 weeks' gestation. Twelve women consented to our protocol. The mean gestational age at preterm premature rupture of membranes was 19 weeks 4 days (range, 13-23 weeks); the mean gestational age at treatment was 20 weeks 5 days (range, 17-23 weeks). All women had a diminution in the amount of amniotic fluid leakage with an increase in amniotic fluid index. Among the 12 pregnancies (13 fetuses), there were 7 surviving neonates. Two women had apparent "resealing" of the membranes. Fibrin sealants in midtrimester rupture of the membranes may lead to improved outcomes and now warrant formal evaluation.

  20. Molecular View of Cholesterol Flip-Flop and Chemical Potential in Different Membrane Environments

    NARCIS (Netherlands)

    Bennett, W. F. Drew; MacCallum, Justin L.; Hinner, Marlon J.; Marrink, Siewert J.; Tieleman, D. Peter

    2009-01-01

    The relative stability of cholesterol in cellular membranes and the thermodynamics of fluctuations from equilibrium have important consequences for sterol trafficking and lateral domain formation. We used molecular dynamics computer simulations to investigate the partitioning of cholesterol in a

  1. Low Copy Numbers of DC-SIGN in Cell Membrane Microdomains: Implications for Structure and Function

    Science.gov (United States)

    Liu, Ping; Wang, Xiang; Itano, Michelle S.; Neumann, Aaron K.; de Silva, Aravinda M.; Jacobson, Ken; Thompson, Nancy L.

    2014-01-01

    Presently, there are few estimates of the number of molecules occupying membrane domains. Using a total internal reflection fluorescence microscopy (TIRFM) imaging approach, based on comparing the intensities of fluorescently labeled microdomains with those of single fluorophores, we measured the occupancy of DC-SIGN, a C-type lectin, in membrane microdomains. DC-SIGN or its mutants were labeled with primary monoclonal antibodies (mAbs) in either dendritic cells (DCs) or NIH3T3 cells, or expressed as GFP fusions in NIH3T3 cells. The number of DC-SIGN molecules per microdomain ranges from only a few to over 20, while microdomain dimensions range from the diffraction limit to > 1μm. The largest fraction of microdomains, appearing at the diffraction limit, in either immature DCs or 3T3 cells contains only 4-8 molecules of DC-SIGN, consistent with our preliminary super-resolution Blink microscopy estimates. We further show that these small assemblies are sufficient to bind and efficiently internalize a small (~50nm) pathogen, dengue virus, leading to infection of host cells. PMID:24313910

  2. Interfacial interactions between Skeletonema costatum extracellular organic matter and metal oxides: Implications for ceramic membrane filtration

    KAUST Repository

    Zaouri, Noor A

    2017-03-21

    In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO2 or Al2O3, were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms. However, the magnitude of these forces was significantly higher on ZrO2 surfaces, irrespective of cation type (Na+ or Ca2+) or concentration. Interestingly, while HMW SKC-EOM interacting forces to Al2O3 were practically insensitive to solution chemistry, the interactions between ZrO2 and HMW SKC-EOM increased with increasing cation concentration in solution. The structure, and lower charge, hydrophilicity, and density of hydroxyl groups on ZrO2 surface would play a key role on favoring zirconia associations with HMW SKC-EOM. The current results contribute to advance our fundamental understanding of Algogenic Organic Matter (AOM) interfacial interactions with metal oxides (i.e., AOM membrane fouling), and would highly assist in the proper selection of membrane material during episodic algal blooms.

  3. Polyamide Thin-Film Composite Membranes for Potential Raw Biogas Purification: Experiments and Modelling.

    Czech Academy of Sciences Publication Activity Database

    Šimčík, Miroslav; Růžička, Marek; Kárászová, Magda; Sedláková, Zuzana; Vejražka, Jiří; Veselý, M.; Čapek, P.; Friess, K.; Izák, Pavel

    2016-01-01

    Roč. 167, JUL 14 (2016), s. 163-173 ISSN 1383-5866 R&D Projects: GA ČR GA14-12695S; GA TA ČR TE01020080; GA MŠk(CZ) LD13018; GA MŠk LH14006 Institutional support: RVO:67985858 Keywords : thin film composite membrane * biogas membrane separation * transport model ing Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.359, year: 2016

  4. Polyamide Thin-Film Composite Membranes for Potential Raw Biogas Purification: Experiments and Modelling.

    Czech Academy of Sciences Publication Activity Database

    Šimčík, Miroslav; Růžička, Marek; Kárászová, Magda; Sedláková, Zuzana; Vejražka, Jiří; Veselý, M.; Čapek, P.; Friess, K.; Izák, Pavel

    2016-01-01

    Roč. 167, JUL 14 (2016), s. 163-173 ISSN 1383-5866 R&D Projects: GA ČR GA14-12695S; GA TA ČR TE01020080; GA MŠk(CZ) LD13018; GA MŠk LH14006 Institutional support: RVO:67985858 Keywords : thin film composite membrane * biogas membrane separation * transport modeling Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.359, year: 2016

  5. Enhancement of membrane stability on magnetic responsive hydrogel microcapsules for potential on-demand cell separation.

    Science.gov (United States)

    Wen, Huiyun; Gao, Ting; Fu, Zizhen; Liu, Xing; Xu, Jiatong; He, Yishu; Xu, Ningxia; Jiao, Ping; Fan, An; Huang, Saipeng; Xue, Weiming

    2017-02-10

    It is of high interest to obtain hydrogel membranes with optimum mechanical stability, which is a prerequisite to the successful fabrication of hydrogel microcapsules for cell separation. In this work, we developed magnetic responsive alginate/chitosan (MAC) hydrogel microcapsules by co-encapsulation of microbial cells and superparamagnetic iron oxide nanoparticles (SPIONs) reacting under a high voltage electrostatic field. We investigated the influence of the molecular weight of chitosan, microcapsules size, and membrane crosslinking time on the swelling behavior of microcapsules as an indicator of stability of the membranes. The results demonstrated that the suitable membrane stability conditions were obtained by a crosslinking of the microspheres with a chitosan presenting a molecular weight of 70kDa for 15-30min resulting in a membrane thickness of approximately 30mm. Considering the need of maintaining the cells inside the microcapsules, fermentation at 37°C and at neutral pH was favorable. Moreover, the MAC microcapsules sizing between 300 and 380μm were suitable for immobilizing Bacillus licheniformis in a 286h multiple fed-bath operation with no leakage of the SPIONs and cells. Overall, the results of this study provided strategies for the rational design of magnetic microcapsules exhibiting suitable mechanical stable membranes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Evaluation of epididymis storage temperature and cryopreservation conditions for improved mitochondrial membrane potential, membrane integrity, sperm motility and in vitro fertilization in bovine epididymal sperm.

    Science.gov (United States)

    Nichi, M; Rijsselaere, T; Losano, Jda; Angrimani, Dsr; Kawai, Gkv; Goovaerts, Igf; Van Soom, A; Barnabe, V H; De Clercq, Jbp; Bols, Pej

    2017-04-01

    The maintaining of the epididymis at lower temperatures during storage and transport improves sperm quality. Our study aimed to test whether epididymis storage temperature (post-mortem) and sperm cryopreservation affect sperm kinetics, membrane integrity, mitochondrial potential and fertility capacity. Thirty-six epididymides were collected from 18 bulls after slaughter and divided into two groups: at 4 or 34°C for 2-3 hr. The sperm was collected from the epididymis cauda. The evaluation consisted of computer-assisted sperm analysis (CASA), SYBR14/PI/JC1 to evaluate membrane integrity, mitochondrial membrane potential (MMP) and measurement of lipid peroxidation (TBARS). The sperm was then frozen using an automatic device. After thawing, sperm samples were evaluated by the same variables and further in vitro fertilization rates. Cryopreservation negatively affected sperm motility in samples stored at 4 and 34°C. Nevertheless, the 4°C samples yielded higher rates of blastocyst formation. Pre-freeze sperm motility, progressive motility and velocity were higher in sperm from epididymis stored at 4°C while post-thaw sperm motility, progressive motility and velocity remained the same among samples from epididymis stored at 4 or 34°C. However, with regard to the kinetic patterns, samples collected from epididymis stored at 34°C had lower values when compared to those stored at 4°C prior the cryopreservation process. Our results indicate that epididymis handling conditions after cryopreservation may affect sperm quality after thawing, especially due to compromised MMP in sperm collected from epididymis stored at higher temperatures. © 2016 Blackwell Verlag GmbH.

  7. Membrane potential of cells and its regulation during aging. 1. Report: the role of energetic metabolism and plasma membrane phospholipid contents.

    Science.gov (United States)

    Frolkis, V V; Tanin, S A; Gorban, E N; Bogatskaya, L N; Sabko, V E

    1987-01-01

    Age-dependent changes in the polarization of the plasma membranes (PM) of various cell types and the mechanisms responsible for its regulation were studied in the experiments on the adult (6-8 months) and old (28-32 months) Wistar male rats. The relationship was found between the specificity of cellular function and the pattern of changes in resting potential (RP) and action potential (AP). In senility, changes occur in the ratio of different pathways of energy provision of the ionic transport: the contribution made by enzymic reactions to the mechanism of maintenance of the PM polarization level is diminished. Changes in the PM phospholipid composition influences considerably the character of the PM electric reactions in aging. An anti-oxidant, dibunol (butilated hydroxytoluene, BHT) has appeared to restore many reactions of the cellular PM in the old animals.

  8. Interfacial interactions between Skeletonema costatum extracellular organic matter and metal oxides: Implications for ceramic membrane filtration.

    Science.gov (United States)

    Zaouri, Noor; Gutierrez, Leonardo; Dramas, Laure; Garces, Daniel; Croue, Jean-Philippe

    2017-06-01

    In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO 2 or Al 2 O 3 , were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms. However, the magnitude of these forces was significantly higher on ZrO 2 surfaces, irrespective of cation type (Na + or Ca 2+ ) or concentration. Interestingly, while HMW SKC-EOM interacting forces to Al 2 O 3 were practically insensitive to solution chemistry, the interactions between ZrO 2 and HMW SKC-EOM increased with increasing cation concentration in solution. The structure, and lower charge, hydrophilicity, and density of hydroxyl groups on ZrO 2 surface would play a key role on favoring zirconia associations with HMW SKC-EOM. The current results contribute to advance our fundamental understanding of Algogenic Organic Matter (AOM) interfacial interactions with metal oxides (i.e., AOM membrane fouling), and would highly assist in the proper selection of membrane material during episodic algal blooms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. [Ion currents through batrachotoxin-modified sodium channels of node of Ranvier membranes at high positive and negative potentials].

    Science.gov (United States)

    Mozhaeva, G N; Naumova, A P; Khodorov, B I

    1983-01-01

    Ionic currents through batrachotoxin-modified sodium channels in frog nerve fibres were measured over a wide range of membrane potentials. At potentials above +80 mV currents decay in time and their steady-state level decreased as potentials increased. "Instantaneous" current measurements have shown that this phenomenon was due to the decrease in net channel conductance. Scorpion toxin affected current kinetics only slightly at these potentials, which suggested that these decays were not caused by usual inactivation process. Externally applied procaine induced slow (tens of ms) potential-dependent block of batrachotoxin-modified channels at large positive potentials. At large negative potentials (above -100 mV) "instantaneus" currents decreased due to fast voltage-dependent block of the channels by calcium ions.

  10. Pharmacological characterization of human excitatory amino acid transporters EAAT1, EAAT2 and EAAT3 in a fluorescence-based membrane potential assay

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Bräuner-Osborne, Hans

    2004-01-01

    We have expressed the human excitatory amino acid transporters EAAT1, EAAT2 and EAAT3 stably in HEK293 cells and characterized the transporters pharmacologically in a conventional [(3) H]-d-aspartate uptake assay and in a fluorescence-based membrane potential assay, the FLIPR Membrane Potential (...

  11. A new laboratory model using bull and boar spermatozoa and fluorescent beads to assess a membrane's occlusive potential.

    Science.gov (United States)

    Szellö, M; Janett, F; Ewald, C; Music, M; Sener, B; Attin, T; Schmidlin, P R

    2016-11-01

    The objective of the present study is to assess the potential of bull and boar spermatozoa and fluorescent beads to be used as a surrogate cell model to determine the cell occlusive potential in vitro using membranes of standardized porosities. A two-chamber model system consisting of upper and lower chambers, which could be separated by membranes, was constructed. Isopore polycarbonate membranes with different standardized pore diameters were used to assess the mobile cellular penetration behavior of spermatozoa or the more passive non-cellular permeability of fluorescent particles (beads) of different diameter and color. In a first experiment, spermatozoa were placed in the lower chamber, whereas semen extender only was placed in the upper chamber. After 10 min of incubation at 37 °C, the sperm number was assessed in the latter. In a second experiment, a bead solution was drawn through resorbable collagen membranes from the upper into the lower chamber by vacuum using a syringe and bead number and size was analyzed by flow cytometry. All experiments were carried out in triplicates. A non-porous polyester membrane was used as negative control to assess the overall tightness of the setup. Boar and bull spermatozoa had average cell body lengths and widths of 9 × 5 μm and were unable to pass through pores ≤2 μm, whereas they were detectable at pore sizes ≥3 μm. Their number increased with increasing pore diameters, i.e., from minimal concentrations of 0.1 × 10 6 /ml for boar and 0.5 × 10 6 /ml for bull spermatozoa at 3 μm to maximal concentrations of 2.1 × 10 6 /ml for boar and 13.1 × 10 6 /ml for bull spermatozoa at 8 μm. The fluorescent beads followed the expected pattern of permeability reliably correlating bead and pore diameter. Within the limitations of this laboratory study and the xenogeneic cell surrogate material, the model allows to easily assess cell and particle penetration through porous structures like

  12. Membrane-active macromolecules kill antibiotic-tolerant bacteria and potentiate antibiotics towards Gram-negative bacteria.

    Directory of Open Access Journals (Sweden)

    Divakara S S M Uppu

    Full Text Available Chronic bacterial biofilms place a massive burden on healthcare due to the presence of antibiotic-tolerant dormant bacteria. Some of the conventional antibiotics such as erythromycin, vancomycin, linezolid, rifampicin etc. are inherently ineffective against Gram-negative bacteria, particularly in their biofilms. Here, we report membrane-active macromolecules that kill slow dividing stationary-phase and antibiotic tolerant cells of Gram-negative bacteria. More importantly, these molecules potentiate antibiotics (erythromycin and rifampicin to biofilms of Gram-negative bacteria. These molecules eliminate planktonic bacteria that are liberated after dispersion of biofilms (dispersed cells. The membrane-active mechanism of these molecules forms the key for potentiating the established antibiotics. Further, we demonstrate that the combination of macromolecules and antibiotics significantly reduces bacterial burden in mouse burn and surgical wound infection models caused by Acinetobacter baumannii and Carbapenemase producing Klebsiella pneumoniae (KPC clinical isolate respectively. Colistin, a well-known antibiotic targeting the lipopolysaccharide (LPS of Gram-negative bacteria fails to kill antibiotic tolerant cells and dispersed cells (from biofilms and bacteria develop resistance to it. On the contrary, these macromolecules prevent or delay the development of bacterial resistance to known antibiotics. Our findings emphasize the potential of targeting the bacterial membrane in antibiotic potentiation for disruption of biofilms and suggest a promising strategy towards developing therapies for topical treatment of Gram-negative infections.

  13. Membrane-active macromolecules kill antibiotic-tolerant bacteria and potentiate antibiotics towards Gram-negative bacteria.

    Science.gov (United States)

    Uppu, Divakara S S M; Konai, Mohini M; Sarkar, Paramita; Samaddar, Sandip; Fensterseifer, Isabel C M; Farias-Junior, Celio; Krishnamoorthy, Paramanandam; Shome, Bibek R; Franco, Octávio L; Haldar, Jayanta

    2017-01-01

    Chronic bacterial biofilms place a massive burden on healthcare due to the presence of antibiotic-tolerant dormant bacteria. Some of the conventional antibiotics such as erythromycin, vancomycin, linezolid, rifampicin etc. are inherently ineffective against Gram-negative bacteria, particularly in their biofilms. Here, we report membrane-active macromolecules that kill slow dividing stationary-phase and antibiotic tolerant cells of Gram-negative bacteria. More importantly, these molecules potentiate antibiotics (erythromycin and rifampicin) to biofilms of Gram-negative bacteria. These molecules eliminate planktonic bacteria that are liberated after dispersion of biofilms (dispersed cells). The membrane-active mechanism of these molecules forms the key for potentiating the established antibiotics. Further, we demonstrate that the combination of macromolecules and antibiotics significantly reduces bacterial burden in mouse burn and surgical wound infection models caused by Acinetobacter baumannii and Carbapenemase producing Klebsiella pneumoniae (KPC) clinical isolate respectively. Colistin, a well-known antibiotic targeting the lipopolysaccharide (LPS) of Gram-negative bacteria fails to kill antibiotic tolerant cells and dispersed cells (from biofilms) and bacteria develop resistance to it. On the contrary, these macromolecules prevent or delay the development of bacterial resistance to known antibiotics. Our findings emphasize the potential of targeting the bacterial membrane in antibiotic potentiation for disruption of biofilms and suggest a promising strategy towards developing therapies for topical treatment of Gram-negative infections.

  14. Assessing the Mitochondrial Membrane Potential in Cells and In Vivo using Targeted Click Chemistry and Mass Spectrometry.

    Science.gov (United States)

    Logan, Angela; Pell, Victoria R; Shaffer, Karl J; Evans, Cameron; Stanley, Nathan J; Robb, Ellen L; Prime, Tracy A; Chouchani, Edward T; Cochemé, Helena M; Fearnley, Ian M; Vidoni, Sara; James, Andrew M; Porteous, Carolyn M; Partridge, Linda; Krieg, Thomas; Smith, Robin A J; Murphy, Michael P

    2016-02-09

    The mitochondrial membrane potential (Δψm) is a major determinant and indicator of cell fate, but it is not possible to assess small changes in Δψm within cells or in vivo. To overcome this, we developed an approach that utilizes two mitochondria-targeted probes each containing a triphenylphosphonium (TPP) lipophilic cation that drives their accumulation in response to Δψm and the plasma membrane potential (Δψp). One probe contains an azido moiety and the other a cyclooctyne, which react together in a concentration-dependent manner by "click" chemistry to form MitoClick. As the mitochondrial accumulation of both probes depends exponentially on Δψm and Δψp, the rate of MitoClick formation is exquisitely sensitive to small changes in these potentials. MitoClick accumulation can then be quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This approach enables assessment of subtle changes in membrane potentials within cells and in the mouse heart in vivo. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Key steps in type III secretion system (T3SS) towards translocon assembly with potential sensor at plant plasma membrane.

    Science.gov (United States)

    Ji, Hongtao; Dong, Hansong

    2015-09-01

    Many plant- and animal-pathogenic Gram-negative bacteria employ the type III secretion system (T3SS) to translocate effector proteins from bacterial cells into the cytosol of eukaryotic host cells. The effector translocation occurs through an integral component of T3SS, the channel-like translocon, assembled by hydrophilic and hydrophobic proteinaceous translocators in a two-step process. In the first, hydrophilic translocators localize to the tip of a proteinaceous needle in animal pathogens, or a proteinaceous pilus in plant pathogens, and associate with hydrophobic translocators, which insert into host plasma membranes in the second step. However, the pilus needs to penetrate plant cell walls in advance. All hydrophilic translocators so far identified in plant pathogens are characteristic of harpins: T3SS accessory proteins containing a unitary hydrophilic domain or an additional enzymatic domain. Two-domain harpins carrying a pectate lyase domain potentially target plant cell walls and facilitate the penetration of the pectin-rich middle lamella by the bacterial pilus. One-domain harpins target plant plasma membranes and may play a crucial role in translocon assembly, which may also involve contrapuntal associations of hydrophobic translocators. In all cases, sensory components in the target plasma membrane are indispensable for the membrane recognition of translocators and the functionality of the translocon. The conjectural sensors point to membrane lipids and proteins, and a phosphatidic acid and an aquaporin are able to interact with selected harpin-type translocators. Interactions between translocators and their sensors at the target plasma membrane are assumed to be critical for translocon assembly. © 2014 BSPP AND JOHN WILEY & SONS LTD.

  16. Early Zn2+-induced effects on membrane potential account for primary heavy metal susceptibility in tolerant and sensitive Arabidopsis species

    Science.gov (United States)

    Kenderešová, Lucia; Staňová, Andrea; Pavlovkin, Ján; Ďurišová, Eva; Nadubinská, Miriam; Čiamporová, Milada; Ovečka, Miroslav

    2012-01-01

    Background and Aims Uptake of heavy metals by plant root cells depends on electro-physiological parameters of the plasma membrane. In this study, responses of the plasma membrane in root cells were analysed where early reactions to the metal ion-induced stress are localized. Three different Arabidopsis species with diverse strategies of their adaptation to heavy metals were compared: sensitive Arabidopsis thaliana and tolerant A. halleri and A. arenosa. Methods Plants of A. thaliana Col-0 ecotype and plants of A. arenosa and A. halleri originating from natural metallicolous populations were exposed to high concentrations of Zn2+. Plants were tested for root growth rate, cellular tolerance, plant morphology and cell death in the root apex. In addition, the membrane potential (EM) of mature cortical root cells and changes in the pH of the liquid culture media were measured. Key Results Primary roots of A. halleri and A. arenosa plants grew significantly better at increased Zn2+ concentrations than A. thaliana plants. Elevated Zn2+ concentrations in the culture medium induced rapid changes in EM. The reaction was species-specific and concentration-dependent. Arabidopsis halleri revealed the highest insensitivity of the plasma membrane and the highest survival rate under prolonged treatment with extra-high concentrations. Plants were able to effectively adjust the pH in the control, but much less at Zn2+-induced lower pH. Conclusions The results indicate a similar mode of early reaction to Zn2+, but with different extent in tolerant and sensitive species of Arabidopsis. The sensitivity of A. thaliana and a high tolerance of A. halleri and A. arenosa were demonstrated. Plasma membrane depolarization was lowest in the hyperaccumulator A. halleri and highest in A. thaliana. This indicates that rapid membrane voltage changes are an excellent tool to monitor the effects of heavy metals. PMID:22645116

  17. Comparison of regulated passive membrane conductance in action potential-firing fast- and slow-twitch muscle.

    Science.gov (United States)

    Pedersen, Thomas Holm; Macdonald, William Alexander; de Paoli, Frank Vincenzo; de Paoli, Frank Vinzenco; Gurung, Iman Singh; Nielsen, Ole Baekgaard

    2009-10-01

    In several pathological and experimental conditions, the passive membrane conductance of muscle fibers (G(m)) and their excitability are inversely related. Despite this capacity of G(m) to determine muscle excitability, its regulation in active muscle fibers is largely unexplored. In this issue, our previous study (Pedersen et al. 2009. J. Gen. Physiol. doi:10.1085/jgp.200910291) established a technique with which biphasic regulation of G(m) in action potential (AP)-firing fast-twitch fibers of rat extensor digitorum longus muscles was identified and characterized with temporal resolution of seconds. This showed that AP firing initially reduced G(m) via ClC-1 channel inhibition but after approximately 1,800 APs, G(m) rose substantially, causing AP excitation failure. This late increase of G(m) reflected activation of ClC-1 and K(ATP) channels. The present study has explored regulation of G(m) in AP-firing slow-twitch fibers of soleus muscle and compared it to G(m) dynamics in fast-twitch fibers. It further explored aspects of the cellular signaling that conveyed regulation of G(m) in AP-firing fibers. Thus, in both fiber types, AP firing first triggered protein kinase C (PKC)-dependent ClC-1 channel inhibition that reduced G(m) by approximately 50%. Experiments with dantrolene showed that AP-triggered SR Ca(2+) release activated this PKC-mediated ClC-1 channel inhibition that was associated with reduced rheobase current and improved function of depolarized muscles, indicating that the reduced G(m) enhanced muscle fiber excitability. In fast-twitch fibers, the late rise in G(m) was accelerated by glucose-free conditions, whereas it was postponed when intermittent resting periods were introduced during AP firing. Remarkably, elevation of G(m) was never encountered in AP-firing slow-twitch fibers, even after 15,000 APs. These observations implicate metabolic depression in the elevation of G(m) in AP-firing fast-twitch fibers. It is concluded that regulation of G(m) is

  18. Muscarinic receptor control of pyramidal neuron membrane potential in the medial prefrontal cortex (mPFC) in rats.

    Science.gov (United States)

    Kurowski, P; Gawlak, M; Szulczyk, P

    2015-09-10

    Damage to the cholinergic input to the prefrontal cortex has been implicated in neuropsychiatric disorders. Cholinergic endings release acetylcholine, which activates nicotinic and/or G-protein-coupled muscarinic receptors. Muscarinic receptors activate transduction systems, which control cellular effectors that regulate the membrane potential in medial prefrontal cortex (mPFC) neurons. The mechanisms responsible for the cholinergic-dependent depolarization of mPFC layer V pyramidal neurons in slices obtained from young rats were elucidated in this study. Glutamatergic and GABAergic transmission as well as tetrodotoxin (TTX)-sensitive Na(+) and voltage-dependent Ca(++) currents were eliminated. Cholinergic receptor stimulation by carbamoylcholine chloride (CCh; 100 μM) evoked depolarization (10.0 ± 1.3 mV), which was blocked by M1/M4 (pirenzepine dihydrochloride, 2 μM) and M1 (VU 0255035, 5 μM) muscarinic receptor antagonists and was not affected by a nicotinic receptor antagonist (mecamylamine hydrochloride, 10 μM). CCh-dependent depolarization was attenuated by extra- (20 μM) or intracellular (50 μM) application of an inhibitor of the βγ-subunit-dependent transduction system (gallein). It was also inhibited by intracellular application of a βγ-subunit-binding peptide (GRK2i, 10μM). mPFC pyramidal neurons express Nav1.9 channels. CCh-dependent depolarization was abolished in the presence of antibodies against Nav1.9 channels in the intracellular solution and augmented by the presence of ProTx-I toxin (100 nM) in the extracellular solution. CCh-induced depolarization was not affected by the following reagents: intracellular transduction system blockers, including U-73122 (10 μM), chelerythrine chloride (5 μM), SQ 22536 (100 μM) and H-89 (2 μM); channel blockers, including Ba(++) ions (200 μM), apamin (100 nM), flufenamic acid (200 μM), 2-APB (200 μM), SKF 96365 (50 μM), and ZD 7288 (50 μM); and a Na(+)/Ca(++) exchanger blocker, benzamil (20

  19. Vanillin, a potential agent to prevent biofouling of reverse osmosis membrane.

    Science.gov (United States)

    Kappachery, Sajeesh; Paul, Diby; Yoon, Jeyong; Kweon, Ji Hyang

    2010-08-01

    Reverse osmosis (RO) membrane systems are widely used in water purification plants. Reduction in plant performance due to biofilm formation over the membrane is an inherent problem. As quorum sensing (QS) mechanisms of microorganisms have been reported to be involved in the formation of biofilm, ways are sought for quorum quenching (QQ) and thereby prevention of biofilm formation. In this study using a chemostat culture run for seven days in a CDC reactor it was found that a natural QQ compound, vanillin considerably suppressed bacterial biofilm formation on RO membrane. There was 97% reduction in biofilm surface coverage, when grown in the presence of vanillin. Similarly, the average thickness, total biomass and the total protein content of the biofilm that formed in the presence of vanillin were significantly less than that of the control. However vanillin had no effect on 1-day old pre-formed biofilm.

  20. 60 Hz electric field changes the membrane potential during burst phase in pancreatic β-cells: in silico analysis.

    Science.gov (United States)

    Neves, Gesilda F; Silva, José R F; Moraes, Renato B; Fernandes, Thiago S; Tenorio, Bruno M; Nogueira, Romildo A

    2014-06-01

    The production, distribution and use of electricity can generate low frequency electric and magnetic fields (50-60 Hz). Considering that some studies showed adverse effects on pancreatic β-cells exposed to these fields; the present study aimed to analyze the effects of 60 Hz electric fields on membrane potential during the silent and burst phases in pancreatic β-cells using a mathematical model. Sinusoidal 60 Hz electric fields with amplitude ranging from 0.5 to 4 mV were applied on pancreatic β-cells model. The sinusoidal electric field changed burst duration, inter-burst intervals (silent phase) and spike sizes. The parameters above presented dose-dependent response with the voltage amplitude applied. In conclusion, theoretical analyses showed that a 60 Hz electric field with low amplitudes changes the membrane potential in pancreatic β-cells.

  1. A nontoxic, photostable and high signal-to-noise ratio mitochondrial probe with mitochondrial membrane potential and viscosity detectivity.

    Science.gov (United States)

    Chen, Yanan; Qi, Jianguo; Huang, Jing; Zhou, Xiaomin; Niu, Linqiang; Yan, Zhijie; Wang, Jianhong

    2018-01-15

    Herein, we reported a yellow emission probe 1-methyl-4-(6-morpholino-1, 3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl) pyridin-1-ium iodide which could specifically stain mitochondria in living immortalized and normal cells. In comparison to the common mitochondria tracker (Mitotracker Deep Red, MTDR), this probe was nontoxic, photostable and ultrahigh signal-to-noise ratio, which could real-time monitor mitochondria for a long time. Moreover, this probe also showed high sensitivity towards mitochondrial membrane potential and intramitochondrial viscosity change. Consequently, this probe was used for imaging mitochondria, detecting changes in mitochondrial membrane potential and intramitochondrial viscosity in physiological and pathological processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Efficient hydrogen isotopologues separation through a tunable potential barrier: The case of a C2N membrane.

    Science.gov (United States)

    Qu, Yuanyuan; Li, Feng; Zhao, Mingwen

    2017-05-03

    Isotopes separation through quantum sieving effect of membranes is quite promising for industrial applications. For the light hydrogen isotopologues (eg. H 2 , D 2 ), the confinement of potential wells in porous membranes to isotopologues was commonly regarded to be crucial for highly efficient separation ability. Here, we demonstrate from first-principles that a potential barrier is also favorable for efficient hydrogen isotopologues separation. Taking an already-synthesized two-dimensional carbon nitride (C 2 N-h2D) as an example, we predict that the competition between quantum tunneling and zero-point-energy (ZPE) effects regulated by the tensile strain leads to high selectivity and permeance. Both kinetic quantum sieving and equilibrium quantum sieving effects are considered. The quantum effects revealed in this work offer a prospective strategy for highly efficient hydrogen isotopologues separation.

  3. Influence of the external conditions on salt retention and pressure-induced electrical potential measured across a composite membrane

    DEFF Research Database (Denmark)

    Benavente, Juana; Jonsson, Gunnar Eigil

    1999-01-01

    Transport on single electrolyte solutions (NaCl and MgCl2) due to pressure gradients across a commercial reverse osmosis membrane was studied by measuring volume flux (J(v)), salt rejection (S) and pressure induced electrical potential (Delta E) in a crossflow cell. The influence on these paramet......Transport on single electrolyte solutions (NaCl and MgCl2) due to pressure gradients across a commercial reverse osmosis membrane was studied by measuring volume flux (J(v)), salt rejection (S) and pressure induced electrical potential (Delta E) in a crossflow cell. The influence...... on these parameters of different external conditions due to hydrodynamic or chemical changes in the feed solutions was also studied. Changes were carried out by variation of the feed solution velocity (Reynolds numbers between 1500 and 3300) or the concentration ratio of mixed electrolytes (r = HCl/NaCl and HCl/MgCl2...

  4. Membrane vesicles in sea water: heterogeneous DNA content and implications for viral abundance estimates

    Science.gov (United States)

    Biller, Steven J; McDaniel, Lauren D; Breitbart, Mya; Rogers, Everett; Paul, John H; Chisholm, Sallie W

    2017-01-01

    Diverse microbes release membrane-bound extracellular vesicles from their outer surfaces into the surrounding environment. Vesicles are found in numerous habitats including the oceans, where they likely have a variety of functional roles in microbial ecosystems. Extracellular vesicles are known to contain a range of biomolecules including DNA, but the frequency with which DNA is packaged in vesicles is unknown. Here, we examine the quantity and distribution of DNA associated with vesicles released from five different bacteria. The average quantity of double-stranded DNA and size distribution of DNA fragments released within vesicles varies among different taxa. Although some vesicles contain sufficient DNA to be visible following staining with the SYBR fluorescent DNA dyes typically used to enumerate viruses, this represents only a small proportion (vesicles. Thus DNA is packaged heterogeneously within vesicle populations, and it appears that vesicles are likely to be a minor component of SYBR-visible particles in natural sea water compared with viruses. Consistent with this hypothesis, chloroform treatment of coastal and offshore seawater samples reveals that vesicles increase epifluorescence-based particle (viral) counts by less than an order of magnitude and their impact is variable in space and time. PMID:27824343

  5. Deformation of a membrane in a pulsatile flow: implications in heart valve design

    Science.gov (United States)

    Hernandez, C.; Guzman, J. E. V.; Zenit, R.

    2011-11-01

    Current designs of heart valves prosthetics have serious disadvantages and health issues for patients who use them. For this reason, a new design that combines durability (mechanical valves) and biocompatibility (biological valves) has to be conceived. Natural valves have very complex geometry because their leaflets have two principal curvatures, one imposed by the holding ring and a second one imposed by the bending of the closing arrangement. The objective of this research is to study the effects of both curvatures on the performance of a leaflet. It is well known that the increase of the curvature results in a larger stiffness, which, in turn, reduces the deflection of a leaflet. We conducted a study to determine the effect of changing the curvature (in two directions) of a flexible membrane when exposed to a steady and pulsatile flows. A study of the flow field that results from this interaction is also conducted by PIV measurements. Preliminary results of the leaflet deflection for many stiffnesses, curvatures and flow conditions will be presented and discussed.

  6. Binding of (/sup 3/H)imipramine to human platelet membranes with compensation for saturable binding to filters and its implication for binding studies with brain membranes

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, O.M.; Wood, K.M.; Williams, D.C.

    1984-08-01

    Apparent specific binding of (/sup 3/H)imipramine to human platelet membranes at high concentrations of imipramine showed deviation from that expected of a single binding site, a result consistent with a low-affinity binding site. The deviation was due to displaceable, saturable binding to the glass fibre filters used in the assays. Imipramine, chloripramine, desipramine, and fluoxetine inhibited binding to filters whereas 5-hydroxytryptamine and ethanol were ineffective. Experimental conditions were developed that eliminated filter binding, allowing assay of high- and low-affinity binding to membranes. Failure to correct for filter binding may lead to overestimation of binding parameters, Bmax and KD for high-affinity binding to membranes, and may also be misinterpreted as indicating a low-affinity binding component in both platelet and brain membranes. Low-affinity binding (KD less than 2 microM) of imipramine to human platelet membranes was demonstrated and its significance discussed.

  7. LIM kinase1 modulates function of membrane type matrix metalloproteinase 1: implication in invasion of prostate cancer cells

    Directory of Open Access Journals (Sweden)

    Chakrabarti Ratna

    2011-01-01

    Full Text Available Abstract Background LIM kinase 1 (LIMK1 is an actin and microtubule cytoskeleton modulatory protein that is overexpressed in a number of cancerous tissues and cells and also promotes invasion and metastasis of prostate and breast cancer cells. Membrane type matrix metalloproteinase 1 (MT1-MMP is a critical modulator of extracellular matrix (ECM turnover through pericellular proteolysis and thus plays crucial roles in neoplastic cell invasion and metastasis. MT1-MMP and its substrates pro-MMP-2 and pro-MMP-9 are often overexpressed in a variety of cancers including prostate cancer and the expression levels correlate with the grade of malignancy in prostate cancer cells. The purpose of this study is to determine any functional relation between LIMK1 and MT1-MMP and its implication in cell invasion. Results Our results showed that treatment with the hydroxamate inhibitor of MT1-MMP, MMP-2 and MMP-9 ilomastat inhibited LIMK1-induced invasion of benign prostate epithelial cells. Over expression of LIMK1 resulted in increased collagenolytic activity of MMP-2, and secretion of pro-MMP2 and pro-MMP-9. Cells over expressing LIMK1 also exhibited increased expression of MT1-MMP, transcriptional activation and its localization to the plasma membrane. LIMK1 physically associates with MT1-MMP and is colocalized with it to the Golgi vesicles. We also noted increased expression of both MT1-MMP and LIMK1 in prostate tumor tissues. Conclusion Our results provide new information on regulation of MT1-MMP function by LIMK1 and showed for the first time, involvement of MMPs in LIMK1 induced cell invasion.

  8. Dietary Tocotrienol/γ-Cyclodextrin Complex Increases Mitochondrial Membrane Potential and ATP Concentrations in the Brains of Aged Mice

    Directory of Open Access Journals (Sweden)

    Anke Schloesser

    2015-01-01

    Full Text Available Brain aging is accompanied by a decrease in mitochondrial function. In vitro studies suggest that tocotrienols, including γ- and δ-tocotrienol (T3, may exhibit neuroprotective properties. However, little is known about the effect of dietary T3 on mitochondrial function in vivo. In this study, we monitored the effect of a dietary T3/γ-cyclodextrin complex (T3CD on mitochondrial membrane potential and ATP levels in the brain of 21-month-old mice. Mice were fed either a control diet or a diet enriched with T3CD providing 100 mg T3 per kg diet for 6 months. Dietary T3CD significantly increased mitochondrial membrane potential and ATP levels compared to those of controls. The increase in MMP and ATP due to dietary T3CD was accompanied by an increase in the protein levels of the mitochondrial transcription factor A (TFAM. Furthermore, dietary T3CD slightly increased the mRNA levels of superoxide dismutase, γ-glutamyl cysteinyl synthetase, and heme oxygenase 1 in the brain. Overall, the present data suggest that T3CD increases TFAM, mitochondrial membrane potential, and ATP synthesis in the brains of aged mice.

  9. Plasma membrane surface potential: dual effects upon ion uptake and toxicity

    Science.gov (United States)

    Electrical properties of plasma membranes (PMs), partially controlled by the ionic composition of the bathing medium, play significant roles in the distribution of ions at the exterior surface of PMs and in the transport of ions across PMs. The effects of coexistent cations (commonly Al3+, Ca2+, Mg...

  10. A new approach for determination of fouling potential by colloidal nanoparticles during reverse osmosis (RO) membrane filtration of seawater

    Science.gov (United States)

    Park, Ji Yeon; Lim, Sungil; Park, Kihong

    2013-04-01

    A direct measurement of number concentration of colloidal nanoparticles (15-450 nm) in water was made with the membrane filtration-differential mobility analyzer technique, and its corresponding flux decline rate (FDR) was determined by laboratory-scale RO fouling test unit using varying number concentrations of silica nanoparticles in artificial seawaters. This relationship was used to predict fouling potential of colloidal nanoparticles in reverse osmosis (RO) membrane process of seawaters in RO plant. It was found that the FDR linearly increased with the increasing number of colloidal nanoparticles for the given concentration range and that the relationship between the number concentration and the FDR also depended on RO membrane surface properties. Data for estimated FDR values for natural seawaters after pretreatment showed a clear difference among samples, which is contrary to the pre-existing index such as silt density index and modified fouling index. Our data suggest that measurement of colloidal nanoparticles is useful for selection of proper pretreatment and successful operation of RO membrane process along with other particle fouling predictors accounting for large particles (>450 nm).

  11. A new approach for determination of fouling potential by colloidal nanoparticles during reverse osmosis (RO) membrane filtration of seawater

    International Nuclear Information System (INIS)

    Park, Ji Yeon; Lim, Sungil; Park, Kihong

    2013-01-01

    A direct measurement of number concentration of colloidal nanoparticles (15–450 nm) in water was made with the membrane filtration-differential mobility analyzer technique, and its corresponding flux decline rate (FDR) was determined by laboratory-scale RO fouling test unit using varying number concentrations of silica nanoparticles in artificial seawaters. This relationship was used to predict fouling potential of colloidal nanoparticles in reverse osmosis (RO) membrane process of seawaters in RO plant. It was found that the FDR linearly increased with the increasing number of colloidal nanoparticles for the given concentration range and that the relationship between the number concentration and the FDR also depended on RO membrane surface properties. Data for estimated FDR values for natural seawaters after pretreatment showed a clear difference among samples, which is contrary to the pre-existing index such as silt density index and modified fouling index. Our data suggest that measurement of colloidal nanoparticles is useful for selection of proper pretreatment and successful operation of RO membrane process along with other particle fouling predictors accounting for large particles (>450 nm).

  12. Eggshell membrane hydrolyzates activate NF-κB in vitro: possible implications for in vivo efficacy

    Directory of Open Access Journals (Sweden)

    Ruff KJ

    2015-02-01

    Full Text Available Kevin J Ruff,1 Paul L Durham,2 Austin O’Reilly,2 F Daniel Long1 1ESM Technologies, LLC, Carthage, MO, USA; 2Center for Biomedical and Life Sciences, Missouri State University, Springfield, MO, USA Purpose: Eggshell membrane (ESM has been shown to contain naturally occurring bioactive components, and biological activities such as reducing proinflammatory cytokines, liver fibrosis, and joint pain in osteoarthritis sufferers have also been reported for ESM matrix as a whole. Nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-κB is a signaling protein found in the cytoplasm of nearly all human and animal cell types and is a primary regulator of immune function. The studies reported herein were designed to investigate the possible role that NF-κB activity might play in the reported biological activities of ESM. Methods: Three ESM hydrolyzates produced via fermentation, enzymatic, or chemical hydrolysis were evaluated in vitro in either human peripheral blood mononuclear cell or THP-1 (human leukemic monocyte cell cultures for NF-κB activity following 4-hour exposure. The hydrolyzates were compared with untreated control cells or cells incubated with lipopolysaccharide or ascorbic acid. The source of ESM activity was also evaluated. Results: NF-κB levels were increased above levels found in untreated cells at all three dilutions (1:100, 1:1,000, and 1:10,000 for the fermentation hydrolyzate of ESM (ESM-FH (P=0.021, P=0.020, P=0.009, respectively in peripheral blood mononuclear cells. The enzymatic hydrolyzate of ESM (ESM-EH also produced statistically significant levels of activated NF-κB at the 1:100 and 1:1,000 dilutions (P=0.004, P=0.006, respectively but fell just shy of significance at the 1:10,000 dilution (P=0.073. Similarly, ESM-FH (P=0.021, P=0.002 and ESM-EH (P=0.007, P=0.007 activated NF-κB in THP-1 cells at 1:1,000 and 1:10,000 dilutions, respectively. The chemical hydrolyzate of ESM (ESM-CH showed statistically

  13. Potassium currents induced by hydrostatic pressure modulate membrane potential and transmitter release in vestibular type II hair cells.

    Science.gov (United States)

    Duong Dinh, Thien An; Haasler, Thorsten; Homann, Georg; Jüngling, Eberhard; Westhofen, Martin; Lückhoff, Andreas

    2009-06-01

    Vestibular type II hair cells respond to increases in the hydrostatic pressure with pressure-dependent K(+) currents. We examined whether such currents may modulate transmitter release (assessed as membrane capacitance increments) by altering membrane potentials and voltage-gated Ca(2+) currents. Capacitance increments were dependent on voltage-gated Ca(2+) influx. Stimulating currents (0.7 nA) in current clamp induced depolarisations that were more negative by 8.7 +/- 2.1 mV when the bath height was elevated from 0.2 to 0.5 cm. In voltage clamp, protocols were used that simulated the time course of the membrane potential in current clamp at either low (control) or high hydrostatic pressure (high bath). The low bath protocol induced significantly larger Ca(2+) currents and increases in capacitance than the high bath protocol. We conclude that pressure-dependent K(+) currents may alter the voltage response of vestibular hair cells to an extent critical for Ca(2+) currents and transmitter release. This mechanism may contribute to vestibular dysfunction in Meniere's disease.

  14. PITX2 Modulates Atrial Membrane Potential and the Antiarrhythmic Effects of Sodium-Channel Blockers.

    Science.gov (United States)

    Syeda, Fahima; Holmes, Andrew P; Yu, Ting Y; Tull, Samantha; Kuhlmann, Stefan Michael; Pavlovic, Davor; Betney, Daniel; Riley, Genna; Kucera, Jan P; Jousset, Florian; de Groot, Joris R; Rohr, Stephan; Brown, Nigel A; Fabritz, Larissa; Kirchhof, Paulus

    2016-10-25

    Antiarrhythmic drugs are widely used to treat patients with atrial fibrillation (AF), but the mechanisms conveying their variable effectiveness are not known. Recent data suggested that paired like homeodomain-2 transcription factor (PITX2) might play an important role in regulating gene expression and electrical function of the adult left atrium (LA). After determining LA PITX2 expression in AF patients requiring rhythm control therapy, the authors assessed the effects of Pitx2c on LA electrophysiology and the effect of antiarrhythmic drugs. LA PITX2 messenger ribonucleic acid (mRNA) levels were measured in 95 patients undergoing thoracoscopic AF ablation. The effects of flecainide, a sodium (Na + )-channel blocker, and d,l-sotalol, a potassium channel blocker, were studied in littermate mice with normal and reduced Pitx2c mRNA by electrophysiological study, optical mapping, and patch clamp studies. PITX2-dependent mechanisms of antiarrhythmic drug action were studied in human embryonic kidney (HEK) cells expressing human Na channels and by modeling human action potentials. Flecainide 1 μmol/l was more effective in suppressing atrial arrhythmias in atria with reduced Pitx2c mRNA levels (Pitx2c +/- ). Resting membrane potential was more depolarized in Pitx2c +/- atria, and TWIK-related acid-sensitive K + channel 2 (TASK-2) gene and protein expression were decreased. This resulted in enhanced post-repolarization refractoriness and more effective Na-channel inhibition. Defined holding potentials eliminated differences in flecainide's effects between wild-type and Pitx2c +/- atrial cardiomyocytes. More positive holding potentials replicated the increased effectiveness of flecainide in blocking human Na v 1.5 channels in HEK293 cells. Computer modeling reproduced an enhanced effectiveness of Na-channel block when resting membrane potential was slightly depolarized. PITX2 mRNA modulates atrial resting membrane potential and thereby alters the effectiveness of Na

  15. Membrane bioreactor wastewater treatment plants reveal diverse yeast and protist communities of potential significance in biofouling.

    Science.gov (United States)

    Liébana, Raquel; Arregui, Lucía; Belda, Ignacio; Gamella, Luis; Santos, Antonio; Marquina, Domingo; Serrano, Susana

    2015-01-01

    The yeast community was studied in a municipal full-scale membrane bioreactor wastewater treatment plant (MBR-WWTP). The unexpectedly high diversity of yeasts indicated that the activated sludge formed a suitable environment for them to proliferate, with cellular concentrations of 2.2 ± 0.8 × 10(3) CFU ml(-1). Sixteen species of seven genera were present in the biological reactor, with Ascomycetes being the most prevalent group (93%). Most isolates were able to grow in a synthetic wastewater medium, adhere to polyethylene surfaces, and develop biofilms of variable complexity. The relationship between yeast populations and the protists in the MBR-WWTP was also studied, revealing that some protist species preyed on and ingested yeasts. These results suggest that yeast populations may play a role in the food web of a WWTP and, to some extent, contribute to membrane biofouling in MBR systems.

  16. A Preliminary Study of Human Amniotic Membrane as a Potential Chondrocyte Carrier

    Directory of Open Access Journals (Sweden)

    L Boo

    2009-11-01

    Full Text Available PURPOSE: To investigate the feasibility of using processed human amniotic membrane (HAM to support the attachment and proliferation of chondrocytes in vitro which in turn can be utilised as a cell delivery vehicle in tissue engineering applications. METHODS: Fresh HAM obtained from patients undergoing routine elective caesarean sections was harvested, processed and dried using either freeze drying (FD or air drying (AD methods prior to sterilisation by gamma irradiation. Isolated, processed and characterised rabbit autologous chondrocytes were seeded on processed HAM and cultured for up to three weeks. Cell attachment and proliferation were examined qualitatively using inverted brightfield microscopy. RESULTS: Processed HAM appeared to allow cell attachment when implanted with chondrocytes. Although cells seeded on AD and FD HAM did not appear to attach as strongly as those seeded on glycerol preserved intact human amniotic membrane, these cells to be proliferated in cell culture conditions. CONCLUSION: Preliminary results show that processed HAM promotes chondrocyte attachment and proliferation.

  17. Proteomic and genomic analysis reveals novel Campylobacter jejuni outer membrane proteins and potential heterogeneity

    Directory of Open Access Journals (Sweden)

    Eleanor Watson

    2014-09-01

    Full Text Available Gram-negative bacterial outer membrane proteins play important roles in the interaction of bacteria with their environment including nutrient acquisition, adhesion and invasion, and antibiotic resistance. In this study we identified 47 proteins within the Sarkosyl-insoluble fraction of Campylobacter jejuni 81-176, using LC–ESI-MS/MS. Comparative analysis of outer membrane protein sequences was visualised to reveal protein distribution within a panel of Campylobacter spp., identifying several C. jejuni-specific proteins. Smith–Waterman analyses of C. jejuni homologues revealed high sequence conservation amongst a number of hypothetical proteins, sequence heterogeneity of other proteins and several proteins which are absent in a proportion of strains.

  18. Stratification of archaeal membrane lipids in the ocean and implications for adaptation and chemotaxonomy of planktonic archaea.

    Science.gov (United States)

    Zhu, Chun; Wakeham, Stuart G; Elling, Felix J; Basse, Andreas; Mollenhauer, Gesine; Versteegh, Gerard J M; Könneke, Martin; Hinrichs, Kai-Uwe

    2016-12-01

    Membrane lipids of marine planktonic archaea have provided unique insights into archaeal ecology and paleoceanography. However, past studies of archaeal lipids in suspended particulate matter (SPM) and sediments mainly focused on a small class of fully saturated glycerol dibiphytanyl glycerol tetraether (GDGT) homologues identified decades ago. The apparent low structural diversity of GDGTs is in strong contrast to the high diversity of metabolism and taxonomy among planktonic archaea. Furthermore, adaptation of archaeal lipids in the deep ocean remains poorly constrained. We report the archaeal lipidome in SPM from diverse oceanic regimes. We extend the known inventory of planktonic archaeal lipids to include numerous unsaturated archaeal ether lipids (uns-AELs). We further reveal (i) different thermal regulations and polar headgroup compositions of membrane lipids between the epipelagic (≤ 100 m) and deep (>100 m) populations of archaea, (ii) stratification of unsaturated GDGTs with varying redox conditions, and (iii) enrichment of tetra-unsaturated archaeol and fully saturated GDGTs in epipelagic and deep oxygenated waters, respectively. Such stratified lipid patterns are consistent with the typical distribution of archaeal phylotypes in marine environments. We, thus, provide an ecological context for GDGT-based paleoclimatology and bring about the potential use of uns-AELs as biomarkers for planktonic Euryarchaeota. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  19. Electron Pathways through Erythrocyte Plasma Membrane in Human Physiology and Pathology: Potential Redox Biomarker?

    Directory of Open Access Journals (Sweden)

    Elena Matteucci

    2007-01-01

    Full Text Available Erythrocytes are involved in the transport of oxygen and carbon dioxide in the body. Since pH is the influential factor in the Bohr-Haldane effect, pHi is actively maintained via secondary active transports Na+/H+ exchange and HC3 -/Cl- anion exchanger. Because of the redox properties of the iron, hemoglobin generates reactive oxygen species and thus, the human erythrocyte is constantly exposed to oxidative damage. Although the adult erythrocyte lacks protein synthesis and cannot restore damaged proteins, it is equipped with high activity of protective enzymes. Redox changes in the cell initiate various signalling pathways. Plasma membrane oxido-reductases (PMORs are transmembrane electron transport systems that have been found in the membranes of all cells and have been extensively characterized in the human erythrocyte. Erythrocyte PMORs transfer reducing equivalents from intracellular reductants to extracellular oxidants, thus their most important role seems to be to enable the cell respond to changes in intra- and extra-cellular redox environments.So far the activity of erythrocyte PMORs in disease states has not been systematically investigated. This review summarizes present knowledge on erythrocyte electron transfer activity in humans (health, type 1 diabetes, diabetic nephropathy, and chronic uremia and hypothesizes an integrated model of the functional organization of erythrocyte plasma membrane where electron pathways work in parallel with transport metabolons to maintain redox homeostasis.

  20. Biophysics of Cell Membrane Lipids in Cancer Drug Resistance: Implications for Drug Transport and Drug Delivery with Nanoparticles

    Science.gov (United States)

    Peetla, Chiranjeevi; Vijayaraghavalu, Sivakumar; Labhasetwar, Vinod

    2013-01-01

    In this review, we focus on the biophysics of cell membrane lipids, particularly when cancers develop acquired drug resistance, and how biophysical changes in resistant cell membrane influence drug transport and nanoparticle-mediated drug delivery. Recent advances in membrane lipid research show the varied roles of lipids in regulating membrane P-glycoprotein function, membrane trafficking, apoptotic pathways, drug transport, and endocytic functions, particularly endocytosis, the primary mechanism of cellular uptake of nanoparticle-based drug delivery systems. Since acquired drug resistance alters lipid biosynthesis, understanding the role of lipids in cell membrane biophysics and its effect on drug transport is critical for developing effective therapeutic and drug delivery approaches to overcoming drug resistance. Here we discuss novel strategies for (a) modulating the biophysical properties of membrane lipids of resistant cells to facilitate drug transport and regain endocytic function and (b) developing effective nanoparticles based on their biophysical interactions with membrane lipids to enhance drug delivery and overcome drug resistance. PMID:24055719

  1. Membrane interactions of oligomeric alpha-synuclein : potential role in Parkinson's disease

    NARCIS (Netherlands)

    van Rooijen, Bart D; Claessens, Mireille M A E; Subramaniam, Vinod

    alpha-Synuclein is a small neuronal protein that has been implicated to play an important role in Parkinson's disease. Genetic mutations and multiplications in the alpha-synuclein gene can cause familial forms of the disease. In aggregated fibrillar form, alpha-synuclein is the main component of

  2. Oxidative stress in sickle cell disease; pathophysiology and potential implications for disease management.

    Science.gov (United States)

    Nur, Erfan; Biemond, Bart J; Otten, Hans-Martin; Brandjes, Dees P; Schnog, John-John B

    2011-06-01

    Sickle cell disease (SCD) is a hemoglobinopathy characterized by hemolytic anemia, increased susceptibility to infections and vaso-occlusion leading to a reduced quality of life and life expectancy. Oxidative stress is an important feature of SCD and plays a significant role in the pathophysiology of hemolysis, vaso-occlusion and ensuing organ damage in sickle cell patients. Reactive oxygen species (ROS) and the (end-)products of their oxidative reactions are potential markers of disease severity and could be targets for antioxidant therapies. This review will summarize the role of ROS in SCD and their potential implication for SCD management. Copyright © 2011 Wiley-Liss, Inc.

  3. Effects of Membrane PEGylation on Entry and Location of Antifungal Drug Itraconazole and Their Pharmacological Implications

    DEFF Research Database (Denmark)

    Dzieciuch-Rojek, Monika; Poojari, Chetan; Bednar, Jan

    2017-01-01

    Itraconazole (ITZ) is an antifungal agent used clinically to treat mycotic infections. However, its therapeutic effects are limited by low solubility in aqueous media. Liposome-based delivery systems (LDS) have been proposed as a delivery mechanism for ITZ to alleviate this problem. Furthermore...... of ITZ incorporation into liposomes both with and without PEGylation because it can provide a potential foundation for the rational design of LDS-based systems for delivery of ITZ, using alternate protective polymers or formulations. Here we have combined atomistic simulations, cryo-TEM, Langmuir film...... to its protective properties, PEGylation significantly increases the stability of liposomes that host ITZ. In a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer without PEGylation, ITZ was found to reside inside the lipid bilayer between the glycerol and the double-bond regions of POPC...

  4. Potential of membrane distillation for production of high quality fruit juice concentrate.

    Science.gov (United States)

    Onsekizoglu Bagci, Pelin

    2015-01-01

    Fruit juices are generally concentrated in order to improve the stability during storage and to reduce handling, packaging, and transportation costs. Thermal evaporation is the most widely used technique in industrial fruit juice concentrate production. In addition to high energy consumption, a large part of the characteristics determining the quality of the fresh juice including aroma, color, vitamins, and antioxidants undergoes remarkable alterations through the use of high operation temperatures. Increasing consumer demand for minimally or naturally processed stable products able to retain as much possible the uniqueness of the fresh fruit has engendered a growing interest for development of nonthermal approaches for fruit juice concentration. Among them, membrane distillation (MD) and its variants have attracted much attention for allowing very high concentrations to be reached under atmospheric pressure and temperatures near ambient temperature. This review will provide an overview of the current status and recent developments in the use of MD for concentration of fruit juices. In addition to the most basic concepts of MD variants, crucial suggestions for membrane selection and operating parameters will be presented. Challenges and future trends for industrial adaptation taking into account the possibility of integrating MD with other existing processes will be discussed.

  5. Plasma membrane proteomics of human breast cancer cell lines identifies potential targets for breast cancer diagnosis and treatment.

    Directory of Open Access Journals (Sweden)

    Yvonne S Ziegler

    Full Text Available The use of broad spectrum chemotherapeutic agents to treat breast cancer results in substantial and debilitating side effects, necessitating the development of targeted therapies to limit tumor proliferation and prevent metastasis. In recent years, the list of approved targeted therapies has expanded, and it includes both monoclonal antibodies and small molecule inhibitors that interfere with key proteins involved in the uncontrolled growth and migration of cancer cells. The targeting of plasma membrane proteins has been most successful to date, and this is reflected in the large representation of these proteins as targets of newer therapies. In view of these facts, experiments were designed to investigate the plasma membrane proteome of a variety of human breast cancer cell lines representing hormone-responsive, ErbB2 over-expressing and triple negative cell types, as well as a benign control. Plasma membranes were isolated by using an aqueous two-phase system, and the resulting proteins were subjected to mass spectrometry analysis. Overall, each of the cell lines expressed some unique proteins, and a number of proteins were expressed in multiple cell lines, but in patterns that did not always follow traditional clinical definitions of breast cancer type. From our data, it can be deduced that most cancer cells possess multiple strategies to promote uncontrolled growth, reflected in aberrant expression of tyrosine kinases, cellular adhesion molecules, and structural proteins. Our data set provides a very rich and complex picture of plasma membrane proteins present on breast cancer cells, and the sorting and categorizing of this data provides interesting insights into the biology, classification, and potential treatment of this prevalent and debilitating disease.

  6. Internalisation of membrane progesterone receptor-α after treatment with progesterone: Potential involvement of a clathrin-dependent pathway.

    Science.gov (United States)

    Foster, Helen; Reynolds, Alan; Stenbeck, Gudrun; Dong, Jing; Thomas, Peter; Karteris, Emmanouil

    2010-01-01

    Internalisation and recycling of seven trans-membrane domain receptors is a critical regulatory event for their signalling. The mechanism(s) by which membrane progesterone receptor-α (mPRα) number is regulated on the cell surface is unclear. In this study, we investigated the cellular distribution of mPRα and mechanisms of mPRα trafficking using a cell line derived from a primary culture of human myometrial cells (M11) as an experimental model. RT-PCR and immunofluorescent analysis demonstrated expression of mPRα in M11 cells with mPRα primarily distributed on the cell surface under basal conditions. For the first time, plasma membrane localisation of mPRα was confirmed using immuno-gold transmission electron microscopy. Stimulation of M11 cells with progesterone (P4, 100 nM) resulted in internalisation of mPRα from the plasma membrane to the cytoplasm (10 min) and subsequent partial translocation back to the cell surface (20 min). We investigated potential endocytotic pathways involved in trafficking of mPRα after its internalisation. Partial co-localisation of clathrin with mPRα was obvious after 10 min of P4 treatment. Of note, chlorpromazine (inhibitor of clathrin-mediated pathway) inhibited the endocytosis of mPRα, whereas treatment with nystatin (inhibitor of caveolae-mediated pathway) did not affect internalisation. Collectively, these data suggest that mPRα is expressed on the cell surface of M11 cells and undergoes endocytosis after P4 stimulation primarily via a clathrin-mediated pathway.

  7. Membrane partitioning of ionic liquid cations, anions and ion pairs - Estimating the bioconcentration potential of organic ions.

    Science.gov (United States)

    Dołżonek, Joanna; Cho, Chul-Woong; Stepnowski, Piotr; Markiewicz, Marta; Thöming, Jorg; Stolte, Stefan

    2017-09-01

    Recent efforts have been directed towards better understanding the persistency and toxicity of ionic liquids (ILs) in the context of the "benign-by-design" approach, but the assessment of their bioaccumulation potential remains neglected. This paper reports the experimental membrane partitioning of IL cations (imidazolium, pyridinium, pyrrolidinium, phosphonium), anions ([C(CN) 3 ] - , [B(CN) 4 ] - , [FSO 2 ) 2 N] - , [(C 2 F 5 ) 3 PF 3 ] - , [(CF 3 SO 2 ) 2 N] - ) and their combinations as a measure for estimating the bioconcentration factor (BCF). Both cations and anions can have a strong affinity for phosphatidylcholine bilayers, which is mainly driven by the hydrophobicity of the ions. This affinity is often reflected in the ecotoxicological impact. Our data revealed that the bioconcentration potential of IL cations and anions is much higher than expected from octanol-water-partitioning based estimations that have recently been presented. For some ILs, the membrane-water partition coefficient reached levels corresponding to BCFs that might become relevant in terms of the "B" (bioaccumulation potential) classification under REACH. However, this preliminary estimation need to be confirmed by in vivo bioconcentration studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Implications of modifying membrane fatty acid composition on membrane oxidation, integrity, and storage viability of freeze-dried probiotic, Lactobacillus acidophilus La-5.

    Science.gov (United States)

    Hansen, Marie-Louise R W; Petersen, Mikael A; Risbo, Jens; Hümmer, Magdalena; Clausen, Anders

    2015-01-01

    The aim of this study was to investigate the effect of altering the fatty acid profile of the lipid membrane on storage survival of freeze-dried probiotic, Lactobacillus acidophilus La-5, as well as study the membrane integrity and lipid oxidation. The fatty acid composition of the lipid membrane of L. acidophilus La-5 was significantly different upon growth in MRS (containing Tween 80, an oleic acid source), or in MRS with Tween 20 (containing C12:0 and C14:0), linoleic, or linolenic acid supplemented. Bacteria grown in MRS showed the highest storage survival rates. No indications of loss of membrane integrity could be found, and membrane integrity could therefore not be connected with loss of viability. Survival of bacteria grown with linoleic or linolenic acid was more negatively affected by the presence of oxygen, than bacteria grown in MRS or with Tween 20 supplemented. A small, but significant, loss of linolenic acid during storage could be identified, and an increase of volatile secondary oxidation products during storage was found for bacteria grown in MRS, or with linoleic, or linolenic acid supplemented, but not for bacteria grown with Tween 20. Overall, the results indicate that lipid oxidation and loss of membrane integrity are not the only or most important detrimental reactions which can occur during storage. By altering the fatty acid composition, it was also found that properties of oleic acid gave rise to more robust bacteria than more saturated or unsaturated fatty acids did. © 2015 American Institute of Chemical Engineers.

  9. Mitochondria-associated endoplasmic reticulum membrane (MAM) integrity is required for insulin signaling and is implicated in hepatic insulin resistance.

    Science.gov (United States)

    Tubbs, Emily; Theurey, Pierre; Vial, Guillaume; Bendridi, Nadia; Bravard, Amélie; Chauvin, Marie-Agnès; Ji-Cao, Jingwei; Zoulim, Fabien; Bartosch, Birke; Ovize, Michel; Vidal, Hubert; Rieusset, Jennifer

    2014-10-01

    Mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) are functional domains between both organelles involved in Ca(2+) exchange, through the voltage-dependent anion channel (VDAC)-1/glucose-regulated protein 75 (Grp75)/inositol 1,4,5-triphosphate receptor (IP3R)-1 complex, and regulating energy metabolism. Whereas mitochondrial dysfunction, ER stress, and altered Ca(2+) homeostasis are associated with altered insulin signaling, the implication of MAM dysfunctions in insulin resistance is unknown. Here we validated an approach based on in situ proximity ligation assay to detect and quantify VDAC1/IP3R1 and Grp75/IP3R1 interactions at the MAM interface. We demonstrated that MAM integrity is required for insulin signaling and that induction of MAM prevented palmitate-induced alterations of insulin signaling in HuH7 cells. Disruption of MAM integrity by genetic or pharmacological inhibition of the mitochondrial MAM protein, cyclophilin D (CypD), altered insulin signaling in mouse and human primary hepatocytes and treatment of CypD knockout mice with metformin improved both insulin sensitivity and MAM integrity. Furthermore, ER-mitochondria interactions are altered in liver of both ob/ob and diet-induced insulin-resistant mice and improved by rosiglitazone treatment in the latter. Finally, increasing organelle contacts by overexpressing CypD enhanced insulin action in primary hepatocytes of diabetic mice. Collectively, our data reveal a new role of MAM integrity in hepatic insulin action and resistance, providing a novel target for the modulation of insulin action. © 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  10. Nonlinear dynamics of the membrane potential of a bursting pacemaker cell

    Science.gov (United States)

    González-Miranda, J. M.

    2012-03-01

    This article presents the results of an exploration of one two-parameter space of the Chay model of a cell excitable membrane. There are two main regions: a peripheral one, where the system dynamics will relax to an equilibrium point, and a central one where the expected dynamics is oscillatory. In the second region, we observe a variety of self-sustained oscillations including periodic oscillation, as well as bursting dynamics of different types. These oscillatory dynamics can be observed as periodic oscillations with different periodicities, and in some cases, as chaotic dynamics. These results, when displayed in bifurcation diagrams, result in complex bifurcation structures, which have been suggested as relevant to understand biological cell signaling.

  11. Characterization of membrane potential-dependent uptake of the novel PET tracer 18F-fluorobenzyl triphenylphosphonium cation.

    Science.gov (United States)

    Madar, Igal; Ravert, Hayden; Nelkin, Barry; Abro, Masroor; Pomper, Martin; Dannals, Robert; Frost, James J

    2007-12-01

    Mitochondrial dysfunction has been attributed a critical role in the etiology and pathogenesis of numerous diseases, and is manifested by alterations of the organelle's membrane potential (Deltapsi(m)). This suggests that Deltapsi(m) measurement can be highly useful for diagnostic purposes. In the current study, we characterized the capability of the novel PET agent (18)F-fluorobenzyl triphenylphosphonium ((18)F-FBnTP) to assess Deltapsi(m), compared with the well-established voltage sensor (3)H-tetraphenylphosphonium ((3)H-TPP). (18)F-FBnTP and (3)H-TPP uptake under conditions known to alter Deltapsi(m) and plasma membrane potential (Deltapsi(p)) was assayed in the H345 lung carcinoma cell line. (18)F-FBnTP biodistribution was assessed in CD1 mice using dynamic PET and ex vivo gamma well counting. (18)F-FBnTP and (3)H-TPP demonstrated similar uptake kinetics and plateau concentrations in H345 cells. Stepwise membrane depolarization resulted in a linear decrease in (18)F-FBnTP cellular uptake, with a slope (-0.58+/-0.06) and correlation coefficient (0.94+/-0.07) similar (p>0.17) to those measured for (3)H-TPP (-0.63+/-0.06 and 0.96+/-0.05, respectively). Selective collapse of Deltapsi(m) caused a substantial decrease in cellular uptake for (18)F-FBnTP (81.6+/-8.1%) and (3)H-TPP (85.4+/-6.7%), compared with control. Exposure to the proapoptotic staurosporine, known to collapse Deltapsi(m), resulted in a decrease of 68.7+/-10.1% and 71.5+/-8.4% in (18)F-FBnTP and (3)H-TPP cellular uptake, respectively. (18)F-FBnTP accumulated mainly in kidney, heart and liver. (18)F-FBnTP is a mitochondria-targeting PET radiopharmaceutical responsive to alterations in membrane potential with voltage-dependent performance similar to that of (3)H-TPP. (18)F-FBnTP is a promising new voltage sensor for detection of physiological and pathological processes associated with mitochondrial dysfunction, such as apoptosis, using PET.

  12. Amniotic membrane-derived mesenchymal cells and their conditioned media: potential candidates for uterine regenerative therapy in the horse.

    Directory of Open Access Journals (Sweden)

    Bruna Corradetti

    Full Text Available Amniotic membrane-derived mesenchymal cells (AMCs are considered suitable candidates for a variety of cell-based applications. In view of cell therapy application in uterine pathologies, we studied AMCs in comparison to cells isolated from the endometrium of mares at diestrus (EDCs being the endometrium during diestrus and early pregnancy similar from a hormonal standpoint. In particular, we demonstrated that amnion tissue fragments (AM shares the same transcriptional profile with endometrial tissue fragments (ED, expressing genes involved in early pregnancy (AbdB-like Hoxa genes, pre-implantation conceptus development (Erα, PR, PGRMC1 and mPR and their regulators (Wnt7a, Wnt4a. Soon after the isolation, only AMCs express Wnt4a and Wnt7a. Interestingly, the expression levels of prostaglandin-endoperoxide synthase 2 (PTGS2 were found greater in AM and AMCs than their endometrial counterparts thus confirming the role of AMCs as mediators of inflammation. The expression of nuclear progesterone receptor (PR, membrane-bound intracellular progesterone receptor component 1 (PGRMC1 and membrane-bound intracellular progesterone receptor (mPR, known to lead to improved endometrial receptivity, was maintained in AMCs over 5 passages in vitro when the media was supplemented with progesterone. To further explore the potential of AMCs in endometrial regeneration, their capacity to support resident cell proliferation was assessed by co-culturing them with EDCs in a transwell system or culturing in the presence of AMC-conditioned medium (AMC-CM. A significant increase in EDC proliferation rate exhibited the crucial role of soluble factors as mediators of stem cells action. The present investigation revealed that AMCs, as well as their derived conditioned media, have the potential to improve endometrial cell replenishment when low proliferation is associated to pregnancy failure. These findings make AMCs suitable candidates for the treatment of endometrosis in

  13. Inhibition of Kv channel expression by NSAIDs depolarizes membrane potential and inhibits cell migration by disrupting calpain signaling.

    Science.gov (United States)

    Silver, Kristopher; Littlejohn, Alaina; Thomas, Laurel; Marsh, Elizabeth; Lillich, James D

    2015-12-15

    Clinical use of non-steroidal anti-inflammatory drugs (NSAIDs) is well known to cause gastrointestinal ulcer formation via several mechanisms that include inhibiting epithelial cell migration and mucosal restitution. The drug-affected signaling pathways that contribute to inhibition of migration by NSAIDs are poorly understood, though previous studies have shown that NSAIDs depolarize membrane potential and suppress expression of calpain proteases and voltage-gated potassium (Kv) channel subunits. Kv channels play significant roles in cell migration and are targets of NSAID activity in white blood cells, but the specific functional effects of NSAID-induced changes in Kv channel expression, particularly on cell migration, are unknown in intestinal epithelial cells. Accordingly, we investigated the effects of NSAIDs on expression of Kv1.3, 1.4, and 1.6 in vitro and/or in vivo and evaluated the functional significance of loss of Kv subunit expression. Indomethacin or NS-398 reduced total and plasma membrane protein expression of Kv1.3 in cultured intestinal epithelial cells (IEC-6). Additionally, depolarization of membrane potential with margatoxin (MgTx), 40mM K(+), or silencing of Kv channel expression with siRNA significantly reduced IEC-6 cell migration and disrupted calpain activity. Furthermore, in rat small intestinal epithelia, indomethacin and NS-398 had significant, yet distinct, effects on gene and protein expression of Kv1.3, 1.4, or 1.6, suggesting that these may be clinically relevant targets. Our results show that inhibition of epithelial cell migration by NSAIDs is associated with decreased expression of Kv channel subunits, and provide a mechanism through which NSAIDs inhibit cell migration and may contribute to NSAID-induced gastrointestinal (GI) toxicity. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. A Biological Security Motivation System for Potential Threats: Are There Implications for Policy-Making?

    Directory of Open Access Journals (Sweden)

    Erik Z Woody

    2013-09-01

    Full Text Available Research indicates that there is a specially adapted, hard-wired brain circuit, the security motivation system, which evolved to manage potential threats, such as the possibility of contamination or predation. The existence of this system may have important implications for policy-making related to security. The system is sensitive to partial, uncertain cues of potential danger, detection of which activates a persistent, potent motivational state of wariness or anxiety. This state motivates behaviours to probe the potential danger, such as checking, and to correct for it, such as washing. Engagement in these behaviours serves as the terminating feedback for the activation of the system. Because security motivation theory makes predictions about what kinds of stimuli activate security motivation and what conditions terminate it, the theory may have applications both in understanding how policy-makers can best influence others, such as the public, and also in understanding the behavior of policy-makers themselves.

  15. Free cholesterol and cholesterol esters in bovine oocytes: Implications in survival and membrane raft organization after cryopreservation.

    Directory of Open Access Journals (Sweden)

    Jorgelina Buschiazzo

    Full Text Available Part of the damage caused by cryopreservation of mammalian oocytes occurs at the plasma membrane. The addition of cholesterol to cell membranes as a strategy to make it more tolerant to cryopreservation has been little addressed in oocytes. In order to increase the survival of bovine oocytes after cryopreservation, we proposed not only to increase cholesterol level of oocyte membranes before vitrification but also to remove the added cholesterol after warming, thus recovering its original level. Results from our study showed that modulation of membrane cholesterol by methyl-β-cyclodextrin (MβCD did not affect the apoptotic status of oocytes and improved viability after vitrification yielding levels of apoptosis closer to those of fresh oocytes. Fluorometric measurements based on an enzyme-coupled reaction that detects both free cholesterol (membrane and cholesteryl esters (stored in lipid droplets, revealed that oocytes and cumulus cells present different levels of cholesterol depending on the seasonal period. Variations at membrane cholesterol level of oocytes were enough to account for the differences found in total cholesterol. Differences found in total cholesterol of cumulus cells were explained by the differences found in both the content of membrane cholesterol and of cholesterol esters. Cholesterol was incorporated into the oocyte plasma membrane as evidenced by comparative labeling of a fluorescent cholesterol. Oocytes and cumulus cells increased membrane cholesterol after incubation with MβCD/cholesterol and recovered their original level after cholesterol removal, regardless of the season. Finally, we evaluated the effect of vitrification on the putative raft molecule GM1. Cholesterol modulation also preserved membrane organization by maintaining ganglioside level at the plasma membrane. Results suggest a distinctive cholesterol metabolic status of cumulus-oocyte complexes (COCs among seasons and a dynamic organizational structure

  16. Hyperthermic potentiation of cisplatin by magnetic nanoparticle heaters is correlated with an increase in cell membrane fluidity

    Science.gov (United States)

    Alvarez-Berríos, Merlis P; Castillo, Amalchi; Mendéz, Janet; Soto, Orlando; Rinaldi, Carlos; Torres-Lugo, Madeline

    2013-01-01

    be a factor contributing to the increase of cDDP uptake in magnetic fluid hyperthermia-treated cells. Overall, our data provide convincing evidence that cell membrane permeability induced by magnetic fluid hyperthermia is significantly greater than that induced by hot water hyperthermia under similar temperature conditions, and is at least one of the mechanisms responsible for potentiation of cDDP by magnetic fluid hyperthermia in Caco-2 cells. PMID:23493492

  17. Cell-Based Phenotyping Reveals QTL for Membrane Potential Maintenance Associated with Hypoxia and Salinity Stress Tolerance in Barley

    Directory of Open Access Journals (Sweden)

    Muhammad B. Gill

    2017-11-01

    Full Text Available Waterlogging and salinity are two major abiotic stresses that hamper crop production world-wide resulting in multibillion losses. Plant abiotic stress tolerance is conferred by many interrelated mechanisms. Amongst these, the cell’s ability to maintain membrane potential (MP is considered to be amongst the most crucial traits, a positive relationship between the ability of plants to maintain highly negative MP and its tolerance to both salinity and waterlogging stress. However, no attempts have been made to identify quantitative trait loci (QTL conferring this trait. In this study, the microelectrode MIFE technique was used to measure the plasma membrane potential of epidermal root cells of 150 double haploid (DH lines of barley (Hordeum vulgare L. from a cross between a Chinese landrace TX9425 and Japanese malting cultivar Naso Nijo under hypoxic conditions. A major QTL for the MP in the epidermal root cells in hypoxia-exposed plants was identified. This QTL was located on 2H, at a similar position to the QTL for waterlogging and salinity tolerance reported in previous studies. Further analysis confirmed that MP showed a significant contribution to both waterlogging and salinity tolerance. The fact that the QTL for MP was controlled by a single major QTL illustrates the power of the single-cell phenotyping approach and opens prospects for fine mapping this QTL and thus being more effective in marker assisted selection.

  18. Recents declines in potential evapotranspiration over South Africa: potential causes and implications for maize yield and irrigation demand

    Science.gov (United States)

    Estes, L. D.; Caylor, K. K.; Chaney, N.; Herrera-Estrada, J. E.; Sheffield, J.; Wood, E. F.

    2014-12-01

    Recent work has identified a 31-year (1979-2010) decline in potential evapotranspiration (PET) during the maize growing season in South Africa, the world's 9th largest producer of that crop. Using a newly-developed, bias-corrected meteorological forcing dataset, we apply an attribution analysis to identify the relative role of four key physical drivers (temperature, net radiation, vapor pressure, and windspeed) in reducing atmospheric demand for water. We conduct a statistical analysis to correlate changes in these four key drivers to potential causal mechanisms, including atmospheric aerosol concentration and changes in the extent of irrigated cropland, which we identify using a novel, high accuracy landcover dataset. Finally, we use the DSSAT maize model, together with counter-factual climate scenarios, to investigate the implications of the PET decline on maize yields and maize irrigation demand. This study illustrates how improved meteorological data, better landcover maps, and crop simulation can be combined to 1) improve understanding of the linkages between the land surface and atmosphere, and 2) help inform crop and irrigation management under changing climates.

  19. On-Chip Electrophoresis in Supported Lipid Bilayer Membranes Achieved Using Low Potentials

    NARCIS (Netherlands)

    van Weerd, Jasper; Krabbenborg, Sven; Eijkel, Jan C.T.; Karperien, Hermanus Bernardus Johannes; Huskens, Jurriaan; Jonkheijm, Pascal

    2014-01-01

    A micro supported lipid bilayer (SLB) electrophoresis method was developed, which functions at low potentials and appreciable operating times. To this end, (hydroxymethyl)-ferrocene (FcCH2OH) was employed to provide an electrochemical reaction at the anode and cathode at low applied potential to

  20. Role of cardiorespiratory synchronization and sleep physiology: effects on membrane potential in the restorative functions of sleep.

    Science.gov (United States)

    Jerath, Ravinder; Harden, Kyler; Crawford, Molly; Barnes, Vernon A; Jensen, Mike

    2014-03-01

    Although sleep physiology has been extensively studied, many of the cellular processes that occur during sleep and the functional significance of sleep remain unclear. The degree of cardiorespiratory synchronization during sleep increases during the progression of slow-wave sleep (SWS). Autonomic nervous system (ANS) activity also assumes a pattern that correlates with the progression of sleep. The ANS is an integral part of physiologic processes that occur during sleep with the respective contribution of parasympathetic and sympathetic activity varying between different sleep stages. In our paper, we attempt to unify the activities of various physiologic systems, namely the cardiac, respiratory, ANS and brain, during sleep into a consolidated picture with particular attention to the membrane potential of neurons. In our unified model, we explore the potential of sleep to promote restorative processes in the brain. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  1. Extracorporeal Membrane Oxygenation for the Support of a Potential Organ Donor with a Fatal Brain Injury before Brain Death Determination

    Directory of Open Access Journals (Sweden)

    Sung Wook Chang

    2016-05-01

    Full Text Available The shortage of available organ donors is a significant problem and various efforts have been made to avoid the loss of organ donors. Among these, extracorporeal membrane oxygenation (ECMO has been introduced to help support and manage potential donors. Many traumatic brain injury patients have healthy organs that might be eligible for donation for transplantation. However, the condition of a donor with a fatal brain injury may rapidly deteriorate prior to brain death determination; this frequently results in the loss of eligible donors. Here, we report the use of venoarterial ECMO to support a potential donor with a fatal brain injury before brain death determination, and thereby preserve donor organs. The patient successfully donated his liver and kidneys after brain death determination.

  2. [The birth of nanobiotechnologies: new nanomaterials, potential uses, toxic effects and implications for public health].

    Science.gov (United States)

    Petrinca, Anna Rita; Pietroiusti, Antonio; Argentin, Gabriella; Cicchetti, Rosadele; Donia, Domenica; Gabrieli, Rosanna; Vignoli, Isabella; Magrini, Andrea; Divizia, Maurizio

    2009-01-01

    Nanotechnologies hold considerable promise of advances in many sectors especially the biomedical field, since the materials used are of the appropriate dimensions to interact with important biological matter such as proteins, DNA and viruses. In this field the use of nanotechnologies will probably be second in importance only to biotechnologies. However many characteristics of nanomaterials that make them so promising from a technological point of view may also lead to negative effects on the environment and human health. It is important therefore that the environmental and work-related exposure effects to these materials be evaluated. In this article the potential uses, toxic effects and public health implications of nanobiotechnologies are discussed.

  3. Women's expectations and experiences of rupture of membranes and views of the potential use of reagent pads for detecting amniotic fluid.

    Science.gov (United States)

    Spiby, Helen; Borrelli, Sara; Hughes, Anita J

    2017-12-01

    To explore first-time mothers' expectations and experiences regarding rupture of membranes at term and their views on the potential use of reagent pads that detect amniotic fluid. There is little information available on women's experiences of spontaneous rupture of membranes, or interest in using methods to confirm rupture of membranes (e.g. reagent pads). Descriptive qualitative study, using focus groups and telephone interviews with women during pregnancy and after the birth of their first baby. Thematic analysis was undertaken to analyse women's responses. Ethics committee approval was obtained. Twenty-five women participated in the study of whom 13 contributed both during pregnancy and postpartum between October 2015-March 2016. Three overarching themes were identified from the data from women's expectations and experiences: uncertainty in how, when and where membranes may rupture; information which was felt to be limited and confirmation of rupture of membranes. The potential use of reagent pads met with varied responses. Women were interested in having facts and figures regarding rupture of membranes, such as characteristics of liquor; volume and probability of membranes rupturing spontaneously at term. Use of a pad as a means of confirmation was viewed as helpful, although the potential for increasing anxiety was raised. © 2017 John Wiley & Sons Ltd.

  4. Membrane progesterone receptor alpha as a potential prognostic biomarker for breast cancer survival: a retrospective study.

    Directory of Open Access Journals (Sweden)

    Mingxuan Xie

    Full Text Available Classically, the actions of progesterone (P4 are attributed to the binding of nuclear progesterone receptor (PR and subsequent activation of its downstream target genes. These mechanisms, however, are not applicable to PR- or basal phenotype breast cancer (BPBC due to lack of PR in these cancers. Recently, the function of membrane progesterone receptor alpha (mPRα in human BPBC cell lines was studied in our lab. We proposed that the signaling cascades of P4→mPRα pathway may play an essential role in controlling cell proliferation and epithelial mesenchymal transition (EMT of breast cancer. Using human breast cancer tissue microarrays, we found in this study that the average intensity of mPRα expression, but not percentage of breast cancer with high level of mPRα expression (mPRα-HiEx, was significantly lower in the TNM stage 4 patients compared to those with TNM 1-3 patients; and both average intensities of mPRα expression and mPRα-HiEx rates were significantly higher in cancers negative for ER, as compared with those cancers with ER+. However, after adjusting for age at diagnosis and/or TNM stage, only average intensities of mPRα expression were associated with ER status. In addition, we found that the rates of mPRα-HiEx were significantly higher in cancers with epithelial growth factor receptor-1 (EGFR+ and high level of Ki67 expression, indicating positive correlation between mPRα over expression and EGFR or Ki67. Further analysis indicated that both mPRα-HiEx rate and average intensity of mPRα expression were significantly higher in HER2+ subtype cancers (i.e. HER2+ER-PR- as compared to ER+ subtype cancers. These data support our hypothesis that P4 modulates the activities of the PI3K and cell proliferation pathways through the caveolar membrane bound growth factor receptors such as mPRα and growth factor receptors. Future large longitudinal studies with larger sample size and survival outcomes are necessary to confirm our

  5. Outcomes of the first 30 cases of an adult extracorporeal membrane oxygenation program: strategies to manage the "learning curve" and implications for intensive care unit risk adjustment models.

    Science.gov (United States)

    Mullany, Daniel V; Bull, Taressa N; Hunt, William; Shekar, Kiran; Thomson, Bruce; Fraser, John F; Ziegenfuss, Marc

    2012-06-01

    We established an adult extracorporeal membrane oxygenation (ECMO) service for cardiorespiratory support in April 2009. Complex therapies may show a learning curve and volume-outcome relationship. To describe our model of care, casemix and outcomes for the first 30 cases together with unique features of this service and potential strategies to manage the learning curve. Data were obtained from the intensive care unit database, medical record and minutes of multidisciplinary ECMO review meetings. The model of care was based heavily on that used at an experienced ECMO centre following Extracorporeal Life Support Organization guidelines. ECMO was established as an ICU-managed, multidisciplinary service with collaboration from other specialties using standardised policies and procedures, staff training and formal case review. A specific budget was allocated to training and education and a clinical perfusionist was present on site for the first 10 cases. Seventeen patients received venoarterial (VA) and 13 received venovenous (VV) ECMO. Median duration of ECMO was 7 days for VA and 15 days for VV ECMO. Median ICU stay was 22 days. Twenty patients were referred from 13 hospitals throughout Queensland. Hospital mortality was 47% for VA ECMO and 15% for VV ECMO. The unique features of this service are the use of a Levitronix CentriMag system as well as the Rotaflow system, and the use of extended daily haemodiafiltration using the Fresenius 4008s ARrT plus connected into the ECMO circuit. The clinical implications of conducting plasma exchange and sustained low-efficiency dialysis via direct ECMO circuit connection using the Fresenius ARrT machine, and using a second system for ECMO support, were notable challenges. Satisfactory outcomes were achieved using an ICU-based multidisciplinary approach with a broadly based education strategy with additional clinical perfusionist support to manage the learning curve.

  6. The ethics of extracorporeal membrane oxygenation in brain-dead potential organ donors.

    Science.gov (United States)

    Dalle Ave, Anne L; Gardiner, Dale; Shaw, David M

    2016-05-01

    Organ-preserving extracorporeal membrane oxygenation (OP-ECMO) is defined as the use of extracorporeal support for the primary purpose of preserving organs for transplantation, rather than to save the patient's life. This paper discusses the ethics of using OP-ECMO in donation after brain determination of death (DBDD) to avoid the loss of organs for transplantation. We review case reports in the literature and analyze the ethical issues raised. We conclude that there is little additional ethical concern in continuing OP-ECMO in patients already on ECMO if they become brain dead. The implementation of OP-ECMO in hemodynamically unstable brain-dead patients is ethically permissible in certain clinical situations but requires specific consent from relatives if the patient's wish to donate is not clear. If no evidence of a patient's wish to donate is available, OP-ECMO is not recommended. In countries with presumed consent legislation, failure to opt out should be considered as a positive wish to donate. If a patient is not-yet brain-dead or is undergoing testing for brain death, OP-ECMO is not recommended. Further research on OP-ECMO is needed to better understand the attitudes of professionals, families, and lay people to ensure agreement on key ethical issues. © 2016 Steunstichting ESOT.

  7. Membrane transport systems and the biodegradation potential and pathogenicity of genus Rhodococcus

    Science.gov (United States)

    de Carvalho, Carla C. C. R.; Costa, Sofia S.; Fernandes, Pedro; Couto, Isabel; Viveiros, Miguel

    2014-01-01

    The Rhodococcus genus contains species with remarkable ability to tolerate toxic compounds and to degrade a myriad of substrates. These substrates have to cross a distinctive cell envelope dominated by mycolic acids anchored in a scaffold of arabinogalactan covalently attached to the cell wall peptidoglycan, and a cellular membrane with phospholipids, whose composition in fatty acids can be rapidly altered in response to environmental conditions. The hydrophobic nature of the cell envelope facilitates the entrance of hydrophobic molecules but some substrates require active transport systems. Additionally, toxic compounds may also be extruded by energy spending efflux systems. In this review, physiological evidences of the use of transport systems by Rhodococcus strains and genomic studies that corroborate their existence are presented and discussed. The recently released complete genomes of several Rhodococcus strains will be the basis for an in silico correlation analysis between the efflux pumps present in the genome and their role on active transport of substrates. These transport systems will be placed on an integrative perspective of the impact of this important genus on biotechnology and health, ranging from bioremediation to antibiotic and biocide resistance. PMID:24772091

  8. Charge Inversion in semi-permeable membranes

    Science.gov (United States)

    Das, Siddhartha; Sinha, Shayandev; Jing, Haoyuan

    Role of semi-permeable membranes like lipid bilayer is ubiquitous in a myriad of physiological and pathological phenomena. Typically, lipid membranes are impermeable to ions and solutes; however, protein channels embedded in the membrane allow the passage of selective, small ions across the membrane enabling the membrane to adopt a semi-permeable nature. This semi-permeability, in turn, leads to electrostatic potential jump across the membrane, leading to effects such as regulation of intracellular calcium, extracellular-vesicle-membrane interactions, etc. In this study, we theoretically demonstrate that this semi-permeable nature may trigger the most remarkable charge inversion (CI) phenomenon in the cytosol-side of the negatively-charged lipid bilayer membrane that are selectively permeable to only positive ions of a given salt. This CI is manifested as the changing of the sign of the electrostatic potential from negative to positive from the membrane-cytosol interface to deep within the cytosol. We study the impact of the parameters such as the concentration of this salt with selectively permeable ions as well as the concentration of an external salt in the development of this CI phenomenon. We anticipate such CI will profoundly influence the interaction of membrane and intra-cellular moieties (e.g., exosome or multi-cellular vesicles) having implications for a host of biophysical processes.

  9. Structural instability of sheath potential distribution and its possible implications for the L/H transition in tokamak plasmas

    International Nuclear Information System (INIS)

    Yoshida, Zensho; Yamada, Hiroshi.

    1988-07-01

    The Bohm equation of electrostatic potential distributions in one-dimensional plasmas has been studied for various Mach numbers and plasma potentials. Solvability and structural stability have been discussed using the Sagdeev potential. Implications of the structural stability for the L/H transitions in tokamak plasmas has been also discussed. (author)

  10. Implications of permeation through intrinsic defects in graphene on the design of defect-tolerant membranes for gas separation.

    Science.gov (United States)

    Boutilier, Michael S H; Sun, Chengzhen; O'Hern, Sean C; Au, Harold; Hadjiconstantinou, Nicolas G; Karnik, Rohit

    2014-01-28

    Gas transport through intrinsic defects and tears is a critical yet poorly understood phenomenon in graphene membranes for gas separation. We report that independent stacking of graphene layers on a porous support exponentially decreases flow through defects. On the basis of experimental results, we develop a gas transport model that elucidates the separate contributions of tears and intrinsic defects on gas leakage through these membranes. The model shows that the pore size of the porous support and its permeance critically affect the separation behavior, and reveals the parameter space where gas separation can be achieved regardless of the presence of nonselective defects, even for single-layer membranes. The results provide a framework for understanding gas transport in graphene membranes and guide the design of practical, selectively permeable graphene membranes for gas separation.

  11. Anti-VDAC3 recombinant antibody decreased human sperm motility and membrane integrity: A potential spermicide for contraception

    Directory of Open Access Journals (Sweden)

    Asmarinah

    2017-11-01

    Full Text Available Objective: To express recombinant protein that comprises an important fragment of human sperm specific voltage dependent anion channel 3 (VDAC3 protein as a potential molecule for generation of antibody, which can affect sperm function, aiming at spermicide development. Methods: The produce of VDAC3 recombinant protein encoded by cDNA sequence of human VDAC3 exon 5-8, based on experimental design of VDAC3 knock-out mice study. And after the purification of various human sperm VDAC3 recombinant proteins, epitope has been predicted in our recombinant protein determined by ElliPro program. Polyclonal antibody was produced for 14 wk. Then anti-VDAC3-exon 5-8 recombinant antiserum was inoculated to human sperm. After the process, antibody VDAC3 protein in human sperm was incubation with anti-VDAC3 recombinant antibody. Finally evaluation the effect of VDAC3 antiserum to human sperm motility and plasma membrane integrity was proceeded. Results: Human VDAC3 recombinant protein was successfully over-expressed in Escherichia coli and purified by affinity chromatography method. Purified human sperm VDAC3 recombinant protein could stimulate immune response in rabbit producing an antibody against VDAC3. Anti-VDAC3 recombinant antibody recognized VDAC3 antigen in human sperm could decrease human sperm motility and membrane integrity significantly. Conclusions: Anti-VDAC3 recombinant polyclonal antibody that we produced in rabbit by ourselves could decrease sperm motility and sperm membrane integrity. The authors suggest this polyclonal antibody could be used as a candidate agent for male contraception in the future. Furthermore, the authors intend to explore the effect of this antibody into sperm function aiming at male contraceptive vaccine development.

  12. Human Amniotic Membrane-Derived Products in Sports Medicine: Basic Science, Early Results, and Potential Clinical Applications.

    Science.gov (United States)

    Riboh, Jonathan C; Saltzman, Bryan M; Yanke, Adam B; Cole, Brian J

    2016-09-01

    Amniotic membrane (AM)-derived products have been successfully used in ophthalmology, plastic surgery, and wound care, but little is known about their potential applications in orthopaedic sports medicine. To provide an updated review of the basic science and preclinical and clinical data supporting the use of AM-derived products and to review their current applications in sports medicine. Systematic review. A systematic search of the literature was conducted using the Medline, EMBASE, and Cochrane databases. The search term amniotic membrane was used alone and in conjunction with stem cell, orthopaedic, tissue engineering, scaffold, and sports medicine. The search identified 6870 articles, 80 of which, after screening of the titles and abstracts, were considered relevant to this study. Fifty-five articles described the anatomy, basic science, and nonorthopaedic applications of AM-derived products. Twenty-five articles described preclinical and clinical trials of AM-derived products for orthopaedic sports medicine. Because the level of evidence obtained from this search was not adequate for systematic review or meta-analysis, a current concepts review on the anatomy, physiology, and clinical uses of AM-derived products is presented. Amniotic membranes have many promising applications in sports medicine. They are a source of pluripotent cells, highly organized collagen, antifibrotic and anti-inflammatory cytokines, immunomodulators, and matrix proteins. These properties may make it beneficial when applied as tissue engineering scaffolds, improving tissue organization in healing, and treatment of the arthritic joint. The current body of evidence in sports medicine is heavily biased toward in vitro and animal studies, with little to no human clinical data. Nonetheless, 14 companies or distributors offer commercial AM products. The preparation and formulation of these products alter their biological and mechanical properties, and a thorough understanding of these

  13. Clinical implications in the shift of syndecan-1 expression from the cell membrane to the cytoplasm in bladder cancer

    International Nuclear Information System (INIS)

    Miyake, Makito; Lawton, Adrienne; Dai, Yunfeng; Chang, Myron; Mengual, Lourdes; Alcaraz, Antonio; Goodison, Steve; Rosser, Charles J

    2014-01-01

    To determine the diagnostic and prognostic capability of urinary and tumoral syndecan-1 (SDC-1) levels in patients with cancer of the urinary bladder. SDC-1 levels were quantitated by enzyme-linked immunosorbent assay (ELISA) in 308 subjects (102 cancer subjects and 206 non-cancer subjects) to assess its diagnostic capabilities in voided urine. The performance of SDC-1 was evaluated using the area under the curve of a receiver operating characteristic curve. In addition, immunohistochemical (IHC) staining assessed SDC-1 protein expression in 193 bladder specimens (185 cancer subjects and 8 non-cancer subjects). Outcomes were correlated to SDC-1 levels. Mean urinary levels of SDC-1 did not differ between the cancer subjects and the non-cancer subjects, however, the mean urinary levels of SDC-1 were reduced in high-grade compared to low-grade disease (p < 0.0001), and in muscle invasive bladder cancer (MIBC) compared to non-muscle invasive bladder cancer (NMIBC) (p = 0.005). Correspondingly, preliminary data note a shift from a membranous cellular localization of SDC-1 in normal tissue, low-grade tumors and NMIBC, to a distinctly cytoplasmic localization in high-grade tumors and MIBC was observed in tissue specimens. Alone urinary SDC-1 may not be a diagnostic biomarker for bladder cancer, but its urinary levels and cellular localization were associated with the differentiation status of patients with bladder tumors. Further studies are warranted to define the potential role for SDC-1 in bladder cancer progression

  14. Regulatory Potential of the RNA Processing Machinery: Implications for Human Disease.

    Science.gov (United States)

    Carey, Kirstyn T; Wickramasinghe, Vihandha O

    2018-04-01

    Splicing and nuclear export of mRNA are critical steps in the gene expression pathway. While RNA processing factors can perform general, essential functions for intron removal and bulk export of mRNA, emerging evidence highlights that the core RNA splicing and export machineries also display regulatory potential. Here, we discuss recent insights into how this regulatory potential can selectively alter gene expression and regulate important biological processes. We also highlight the participation of RNA processing pathways in the cellular response to DNA damage at multiple levels. These findings have important implications for the contribution of selective mRNA processing and export to the development of human cancers and neurodegenerative disorders. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

  15. Sex hormones and adult hippocampal neurogenesis: Regulation, implications, and potential mechanisms.

    Science.gov (United States)

    Mahmoud, Rand; Wainwright, Steven R; Galea, Liisa A M

    2016-04-01

    Neurogenesis within the adult hippocampus is modulated by endogenous and exogenous factors. Here, we review the role of sex hormones in the regulation of adult hippocampal neurogenesis in males and females. The review is framed around the potential functional implications of sex hormone regulation of adult hippocampal neurogenesis, with a focus on cognitive function and mood regulation, which may be related to sex differences in incidence and severity of dementia and depression. We present findings from preclinical studies of endogenous fluctuations in sex hormones relating to reproductive function and ageing, and from studies of exogenous hormone manipulations. In addition, we discuss the modulating roles of sex, age, and reproductive history on the relationship between sex hormones and neurogenesis. Because sex hormones have diverse targets in the central nervous system, we overview potential mechanisms through which sex hormones may influence hippocampal neurogenesis. Lastly, we advocate for a more systematic consideration of sex and sex hormones in studying the functional implications of adult hippocampal neurogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Vancomycin Dosing in Pediatric Extracorporeal Membrane Oxygenation: Potential Impacts of New Technologies.

    Science.gov (United States)

    Lonabaugh, Kevin P; Lunsford, Kelly J; Fang, Gary Y; Kaufman, David A; Addison, Samuel D; Buck, Marcia L

    2017-01-01

    The objective of the current study was to evaluate the doses of vancomycin used to obtain therapeutic drug concentrations in pediatric patients on extracorporeal membrane oxygenation (ECMO), using new ECMO technologies. This was a single-center, retrospective study of patients treated with vancomycin while receiving ECMO using low-volume circuit technology. A total of 28 patients were included in the analysis of the primary endpoint. Patients had a median age of 6 weeks (0-11 years) and a median weight of 3.45 kg (2.44-37.2 kg). Ultrafiltration was used in 89.3% of patients at initiation of ECMO regardless of baseline renal function, resulting in a median urine output of 2 mL/kg/hr at the time of the final vancomycin dose. Most patients started vancomycin at the same time as ECMO. The median total daily dose was 30 mg/kg/day. The median total daily dose in a subset of patients less than one year of age was 20 mg/kg/day. Nearly all patients had at least 1 therapeutic trough serum vancomycin concentration. A total of 16 patients completed their vancomycin course using an interval of every 12 hours or shorter. Half-life was calculated in a subset of 11 patients and the mean was found to be 12.3 ± 2.8 hours. An initial dosing interval of every 12 hours to provide a total daily dose of 30 mg/kg/day is a possible option in pediatric patients on ECMO provided that renal function is normal at baseline. Monitoring of serum vancomycin concentrations for adjustment of dosing is required throughout therapy and is still warranted.

  17. Membrane potential independent transport of NH3in the absence of ammonium permeases in Saccharomyces cerevisiae.

    Science.gov (United States)

    Cueto-Rojas, Hugo F; Milne, Nicholas; van Helmond, Ward; Pieterse, Mervin M; van Maris, Antonius J A; Daran, Jean-Marc; Wahl, S Aljoscha

    2017-04-17

    Microbial production of nitrogen containing compounds requires a high uptake flux and assimilation of the N-source (commonly ammonium), which is generally coupled with ATP consumption and negatively influences the product yield. In the industrial workhorse Saccharomyces cerevisiae, ammonium (NH 4 + ) uptake is facilitated by ammonium permeases (Mep1, Mep2 and Mep3), which transport the NH 4 + ion, resulting in ATP expenditure to maintain the intracellular charge balance and pH by proton export using the plasma membrane-bound H + -ATPase. To decrease the ATP costs for nitrogen assimilation, the Mep genes were removed, resulting in a strain unable to uptake the NH 4 + ion. Subsequent analysis revealed that growth of this ∆mep strain was dependent on the extracellular NH 3 concentrations. Metabolomic analysis revealed a significantly higher intracellular NH X concentration (3.3-fold) in the ∆mep strain than in the reference strain. Further proteomic analysis revealed significant up-regulation of vacuolar proteases and genes involved in various stress responses. Our results suggest that the uncharged species, NH 3 , is able to diffuse into the cell. The measured intracellular/extracellular NH X ratios under aerobic nitrogen-limiting conditions were consistent with this hypothesis when NH x compartmentalization was considered. On the other hand, proteomic analysis indicated a more pronounced N-starvation stress response in the ∆mep strain than in the reference strain, which suggests that the lower biomass yield of the ∆mep strain was related to higher turnover rates of biomass components.

  18. Therapeutic implications of disorders of cell death signalling: membranes, micro-environment, and eicosanoid and docosanoid metabolism.

    Science.gov (United States)

    Davidson, J; Rotondo, D; Rizzo, M T; Leaver, H A

    2012-06-01

    Disruptions of cell death signalling occur in pathological processes, such as cancer and degenerative disease. Increased knowledge of cell death signalling has opened new areas of therapeutic research, and identifying key mediators of cell death has become increasingly important. Early triggering events in cell death may provide potential therapeutic targets, whereas agents affecting later signals may be more palliative in nature. A group of primary mediators are derivatives of the highly unsaturated fatty acids (HUFAs), particularly oxygenated metabolites such as prostaglandins. HUFAs, esterified in cell membranes, act as critical signalling molecules in many pathological processes. Currently, agents affecting HUFA metabolism are widely prescribed in diseases involving disordered cell death signalling. However, partly due to rapid metabolism, their role in cell death signalling pathways is poorly characterized. Recently, HUFA-derived mediators, the resolvins/protectins and endocannabinoids, have added opportunities to target selective signals and pathways. This review will focus on the control of cell death by HUFA, eicosanoid (C20 fatty acid metabolites) and docosanoid (C22 metabolites), HUFA-derived lipid mediators, signalling elements in the micro-environment and their potential therapeutic applications. Further therapeutic approaches will involve cell and molecular biology, the multiple hit theory of disease progression and analysis of system plasticity. Advances in the cell biology of eicosanoid and docosanoid metabolism, together with structure/function analysis of HUFA-derived mediators, will be useful in developing therapeutic agents in pathologies characterized by alterations in cell death signalling. © 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.

  19. Molecular-based detection of potentially pathogenic bacteria in membrane bioreactor (MBR) systems treating municipal wastewater: a case study.

    Science.gov (United States)

    Harb, Moustapha; Hong, Pei-Ying

    2017-02-01

    Although membrane bioreactor (MBR) systems provide better removal of pathogens compared to conventional activated sludge processes, they do not achieve total log removal. The present study examines two MBR systems treating municipal wastewater, one a full-scale MBR plant and the other a lab-scale anaerobic MBR. Both of these systems were operated using microfiltration (MF) polymeric membranes. High-throughput sequencing and digital PCR quantification were utilized to monitor the log removal values (LRVs) of associated pathogenic species and their abundance in the MBR effluents. Results showed that specific removal rates vary widely regardless of the system employed. Each of the two MBR effluents' microbial communities contained genera associated with opportunistic pathogens (e.g., Pseudomonas, Acinetobacter) with a wide range of log reduction values (5.5). Digital PCR further confirmed that these bacterial groups included pathogenic species, in several instances at LRVs different than those for their respective genera. These results were used to evaluate the potential risks associated both with the reuse of the MBR effluents for irrigation purposes and with land application of the activated sludge from the full-scale MBR system.

  20. Protonophoric action of triclosan causes calcium efflux from mitochondria, plasma membrane depolarization and bursts of miniature end-plate potentials.

    Science.gov (United States)

    Popova, Lyudmila B; Nosikova, Ekaterina S; Kotova, Elena A; Tarasova, Ekaterina O; Nazarov, Pavel A; Khailova, Lyudmila S; Balezina, Olga P; Antonenko, Yuri N

    2018-01-06

    The formerly widely used broad-spectrum biocide triclosan (TCS) has now become a subject of special concern due to its accumulation in the environment and emerging diverse toxicity. Despite the common opinion that TCS is an uncoupler of oxidative phosphorylation in mitochondria, there have been so far no studies of protonophoric activity of this biocide on artificial bilayer lipid membranes (BLM). Yet only few works have indicated the relationship between TCS impacts on mitochondria and nerve cell functioning. Here, we for the first time report data on a high protonophoric activity of TCS on planar BLM. TCS proved to be a more effective protonophore on planar BLM, than classical uncouplers. Correlation between a strong depolarizing effect of TCS on bacterial membranes and its bactericidal action on Bacillus subtilis might imply substantial contribution of TCS protonophoric activity to its antimicrobial efficacy. Protonophoric activity of TCS, monitored by proton-dependent mitochondrial swelling, resulted in Ca 2+ efflux from mitochondria. A comparison of TCS effects on molluscan neurons with those of conventional mitochondrial uncouplers allowed us to ascribe the TCS-induced neuronal depolarization and suppression of excitability to the consequences of mitochondrial deenergization. Also similar to the action of common uncouplers, TCS caused a pronounced increase in frequency of miniature end-plate potentials at neuromuscular junctions. Thus, the TCS-induced mitochondrial uncoupling could alter neuronal function through distortion of Ca 2+ homeostasis. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Molecular-based detection of potentially pathogenic bacteria in membrane bioreactor (MBR) systems treating municipal wastewater: a case study

    KAUST Repository

    Harb, Moustapha

    2016-12-24

    Although membrane bioreactor (MBR) systems provide better removal of pathogens compared to conventional activated sludge processes, they do not achieve total log removal. The present study examines two MBR systems treating municipal wastewater, one a full-scale MBR plant and the other a lab-scale anaerobic MBR. Both of these systems were operated using microfiltration (MF) polymeric membranes. High-throughput sequencing and digital PCR quantification were utilized to monitor the log removal values (LRVs) of associated pathogenic species and their abundance in the MBR effluents. Results showed that specific removal rates vary widely regardless of the system employed. Each of the two MBR effluents’ microbial communities contained genera associated with opportunistic pathogens (e.g., Pseudomonas, Acinetobacter) with a wide range of log reduction values (< 2 to >5.5). Digital PCR further confirmed that these bacterial groups included pathogenic species, in several instances at LRVs different than those for their respective genera. These results were used to evaluate the potential risks associated both with the reuse of the MBR effluents for irrigation purposes and with land application of the activated sludge from the full-scale MBR system.

  2. Potential of ultraviolet widefield imaging and multiphoton microscopy for analysis of dehydroergosterol in cellular membranes

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Brewer, Jonathan R.; Bagatolli, Luis

    2011-01-01

    Dehydroergosterol (DHE) is an intrinsically fluorescent sterol with absorption/emission in the ultraviolet (UV) region and biophysical properties similar to those of cholesterol. We compared the potential of UV-sensitive low-light-level wide-field (UV-WF) imaging with that of multiphoton (MP...

  3. The potential impact of membrane cascading on downstream processing of oligosaccharides

    NARCIS (Netherlands)

    Patil, N.V.; Janssen, A.E.M.; Boom, R.M.

    2014-01-01

    To assess the potential use of ideal nanofiltration cascades for the industrial fractionation of oligosac- charides, simulations of single, three and five stage NF cascades were carried out.Three and five stage ideal cascades show significant improvement in separation with diafiltration compared to

  4. Membrane and envelope virus proteins co-expressed as lysosome associated membrane protein (LAMP fused antigens: a potential tool to develop DNA vaccines against flaviviruses

    Directory of Open Access Journals (Sweden)

    Rafael Dhalia

    2009-12-01

    Full Text Available Vaccination is the most practical and cost-effective strategy to prevent the majority of the flavivirus infection to which there is an available vaccine. However, vaccines based on attenuated virus can potentially promote collateral side effects and even rare fatal reactions. Given this scenario, the developent of alternative vaccination strategies such as DNA-based vaccines encoding specific flavivirus sequences are being considered. Endogenous cytoplasmic antigens, characteristically plasmid DNA-vaccine encoded, are mainly presented to the immune system through Major Histocompatibility Complex class I - MHC I molecules. The MHC I presentation via is mostly associated with a cellular cytotoxic response and often do not elicit a satisfactory humoral response. One of the main strategies to target DNA-encoded antigens to the MHC II compartment is expressing the antigen within the Lysosome-Associated Membrane Protein (LAMP. The flavivirus envelope protein is recognized as the major virus surface protein and the main target for neutralizing antibodies. Different groups have demonstrated that co-expression of flavivirus membrane and envelope proteins in mammalian cells, fused with the carboxyl-terminal of LAMP, is able to induce satisfactory levels of neutralizing antibodies. Here we reviewed the use of the envelope flavivirus protein co-expression strategy as LAMP chimeras with the aim of developing DNA vaccines for dengue, West Nile and yellow fever viruses.A vacinação é a estratégia mais prática e o melhor custo-benefício para prevenir a maioria das infecções dos flavivirus, para os quais existe vacina disponível. Entretanto, as vacinas baseadas em vírus atenuados podem potencialmente promover efeitos colaterais e, mais raramente, reações fatais. Diante deste cenário, o desenvolvimento de estratégias alternativas de vacinação, como vacinas baseadas em DNA codificando seqüências específicas dos flavivirus, está sendo considerado

  5. Discovery of membrane active benzimidazole quinolones-based topoisomerase inhibitors as potential DNA-binding antimicrobial agents.

    Science.gov (United States)

    Zhang, Ling; Addla, Dinesh; Ponmani, Jeyakkumar; Wang, Ao; Xie, Dan; Wang, Ya-Nan; Zhang, Shao-Lin; Geng, Rong-Xia; Cai, Gui-Xin; Li, Shuo; Zhou, Cheng-He

    2016-03-23

    A series of novel benzimidazole quinolones as potential antimicrobial agents were designed and synthesized. Most of the prepared compounds exhibited good or even stronger antimicrobial activities in comparison with reference drugs. The most potent compound 15m was membrane active and did not trigger the development of resistance in bacteria. It not only inhibited the formation of biofilms but also disrupted the established Staphylococcus aureus and Escherichia coli biofilms. It was able to inhibit the relaxation activity of E. coli topoisomerase IV at 10 μM concentration. Moreover, this compound also showed low toxicity against mammalian cells. Molecular modeling and experimental investigation of compound 15m with DNA suggested that this compound could effectively bind with DNA to form a steady 15m-DNA complex which might further block DNA replication to exert the powerful bioactivities. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  6. Effect of ethanol on action potential and ionic membrane currents in rat ventricular myocytes

    Czech Academy of Sciences Publication Activity Database

    Bébarová, M.; Matejovič, P.; Pásek, Michal; Ohlídalová, D.; Jansová, D.; Šimurdová, M.; Šimurda, J.

    2010-01-01

    Roč. 200, č. 4 (2010), s. 301-314 ISSN 1748-1708 Institutional research plan: CEZ:AV0Z20760514 Keywords : action potential * ethanol * rat ventricular myocyte Subject RIV: BO - Biophysics Impact factor: 3.138, year: 2010 http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=15&SID=Y1pmpi@7k2HPEc8ehEE&page=1&doc=1&colname=WOS

  7. Synaptic NMDA Receptor-Dependent Ca2+ Entry Drives Membrane Potential and Ca2+ Oscillations in Spinal Ventral Horn Neurons

    Science.gov (United States)

    Alpert, Michael H.; Alford, Simon

    2013-01-01

    During vertebrate locomotion, spinal neurons act as oscillators when initiated by glutamate release from descending systems. Activation of NMDA receptors initiates Ca2+-mediated intrinsic membrane potential oscillations in central pattern generator (CPG) neurons. NMDA receptor-dependent intrinsic oscillations require Ca2+-dependent K+ (KCa2) channels for burst termination. However, the location of Ca2+ entry mediating KCa2 channel activation, and type of Ca2+ channel – which includes NMDA receptors and voltage-gated Ca2+ channels (VGCCs) – remains elusive. NMDA receptor-dependent Ca2+ entry necessitates presynaptic release of glutamate, implying a location at active synapses within dendrites, whereas VGCC-dependent Ca2+ entry is not similarly constrained. Where Ca2+ enters relative to KCa2 channels is crucial to information processing of synaptic inputs necessary to coordinate locomotion. We demonstrate that Ca2+ permeating NMDA receptors is the dominant source of Ca2+ during NMDA-dependent oscillations in lamprey spinal neurons. This Ca2+ entry is synaptically located, NMDA receptor-dependent, and sufficient to activate KCa2 channels at excitatory interneuron synapses onto other CPG neurons. Selective blockade of VGCCs reduces whole-cell Ca2+ entry but leaves membrane potential and Ca2+ oscillations unaffected. Furthermore, repetitive oscillations are prevented by fast, but not slow, Ca2+ chelation. Taken together, these results demonstrate that KCa2 channels are closely located to NMDA receptor-dependent Ca2+ entry. The close spatial relationship between NMDA receptors and KCa2 channels provides an intrinsic mechanism whereby synaptic excitation both excites and subsequently inhibits ventral horn neurons of the spinal motor system. This places the components necessary for oscillation generation, and hence locomotion, at glutamatergic synapses. PMID:23646190

  8. Inferring Trial-to-Trial Excitatory and Inhibitory Synaptic Inputs from Membrane Potential using Gaussian Mixture Kalman Filtering

    Directory of Open Access Journals (Sweden)

    Milad eLankarany

    2013-09-01

    Full Text Available Time-varying excitatory and inhibitory synaptic inputs govern activity of neurons and process information in the brain. The importance of trial-to-trial fluctuations of synaptic inputs has recently been investigated in neuroscience. Such fluctuations are ignored in the most conventional techniques because they are removed when trials are averaged during linear regression techniques. Here, we propose a novel recursive algorithm based on Gaussian mixture Kalman filtering for estimating time-varying excitatory and inhibitory synaptic inputs from single trials of noisy membrane potential in current clamp recordings. The Kalman filtering is followed by an expectation maximization algorithm to infer the statistical parameters (time-varying mean and variance of the synaptic inputs in a non-parametric manner. As our proposed algorithm is repeated recursively, the inferred parameters of the mixtures are used to initiate the next iteration. Unlike other recent algorithms, our algorithm does not assume an a priori distribution from which the synaptic inputs are generated. Instead, the algorithm recursively estimates such a distribution by fitting a Gaussian mixture model. The performance of the proposed algorithms is compared to a previously proposed PF-based algorithm (Paninski et al., 2012 with several illustrative examples, assuming that the distribution of synaptic input is unknown. If noise is small, the performance of our algorithms is similar to that of the previous one. However, if noise is large, they can significantly outperform the previous proposal. These promising results suggest that our algorithm is a robust and efficient technique for estimating time varying excitatory and inhibitory synaptic conductances from single trials of membrane potential recordings.

  9. Dissolved effluent organic matter: Characteristics and potential implications in wastewater treatment and reuse applications.

    Science.gov (United States)

    Michael-Kordatou, I; Michael, C; Duan, X; He, X; Dionysiou, D D; Mills, M A; Fatta-Kassinos, D

    2015-06-15

    Wastewater reuse is currently considered globally as the most critical element of sustainable water management. The dissolved effluent organic matter (dEfOM) present in biologically treated urban wastewater, consists of a heterogeneous mixture of refractory organic compounds with diverse structures and varying origin, including dissolved natural organic matter, soluble microbial products, endocrine disrupting compounds, pharmaceuticals and personal care products residues, disinfection by-products, metabolites/transformation products and others, which can reach the aquatic environment through discharge and reuse applications. dEfOM constitutes the major fraction of the effluent organic matter (EfOM) and due to its chemical complexity, it is necessary to utilize a battery of complementary techniques to adequately describe its structural and functional character. dEfOM has been shown to exhibit contrasting effects towards various aquatic organisms. It decreases metal uptake, thus potentially reducing their bioavailability to exposed organisms. On the other hand, dEfOM can be adsorbed on cell membranes inducing toxic effects. This review paper evaluates the performance of various advanced treatment processes (i.e., membrane filtration and separation processes, activated carbon adsorption, ion-exchange resin process, and advanced chemical oxidation processes) in removing dEfOM from wastewater effluents. In general, the literature findings reveal that dEfOM removal by advanced treatment processes depends on the type and the amount of organic compounds present in the aqueous matrix, as well as the operational parameters and the removal mechanisms taking place during the application of each treatment technology. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Differences in the stable isotope signatures of seabird egg membrane and albumen--implications for non-invasive studies.

    Science.gov (United States)

    Quillfeldt, Petra; McGill, Rona A R; Masello, Juan F; Poisbleau, Maud; van Noordwijk, Hendrika; Demongin, Laurent; Furness, Robert W

    2009-12-01

    In many bird species, egg membranes can be obtained non-invasively after the chicks have hatched, and stable isotope analysis of egg membranes can be used to study the diet and foraging distribution of these birds during egg formation. It has been suggested that the enrichment factors of albumen and egg membranes differ for 13C, but are similar for 15N. In this study, we compared carbon and nitrogen stable isotopes of the membranes and albumen of individual eggs of three wild seabird species, the Southern Rockhopper penguin Eudyptes chrysocome, the Imperial shag Phalacrocorax atriceps albiventer, and the Thin-billed prion Pachyptila belcheri. We also included chicken eggs for comparison. Egg membranes were generally enriched in 13C, compared with albumen. The difference varied between species, with 2.1 per thousand in Rockhopper penguins, 1.6 per thousand in Imperial shags, but only 0.5 per thousand in Thin-billed prions and 0.4 per thousand in chicken eggs. Egg membranes were slightly enriched in 15N in Imperial shags (0.9 per thousand) and chickens (0.5 per thousand), compared with albumen, while there was no difference for Thin-billed prions and Rockhopper penguins. The isotopic values of carbon and nitrogen were correlated between albumen and egg membranes of individual eggs, suggesting that egg membranes can be used reliably to investigate trophic differences between individuals, seasons or colonies. Species-specific mathematical corrections could be used to compare results across studies that use different egg components. Copyright 2009 John Wiley & Sons, Ltd.

  11. Synchronous plasma membrane electrochemical potential oscillations during yeast colony development and aging

    Czech Academy of Sciences Publication Activity Database

    Palková, Z.; Váchová, Libuše; Gášková, D.; Kučerová, Helena

    2009-01-01

    Roč. 26, č. 4 (2009), s. 228-235 ISSN 0968-7688 R&D Projects: GA ČR GA204/05/0294; GA ČR GA204/08/0718; GA MŠk(CZ) LC531 Grant - others:US(US) Howard Hughes Medical Institute International Research Award (#55005623) Institutional research plan: CEZ:AV0Z50200510 Keywords : yeast colony population * transmembrane potential oscillations * cell energetics Subject RIV: EE - Microbiology, Virology Impact factor: 2.777, year: 2009

  12. Predicting potential global distributions of two Miscanthus grasses: implications for horticulture, biofuel production, and biological invasions.

    Science.gov (United States)

    Hager, Heather A; Sinasac, Sarah E; Gedalof, Ze'ev; Newman, Jonathan A

    2014-01-01

    In many regions, large proportions of the naturalized and invasive non-native floras were originally introduced deliberately by humans. Pest risk assessments are now used in many jurisdictions to regulate the importation of species and usually include an estimation of the potential distribution in the import area. Two species of Asian grass (Miscanthus sacchariflorus and M. sinensis) that were originally introduced to North America as ornamental plants have since escaped cultivation. These species and their hybrid offspring are now receiving attention for large-scale production as biofuel crops in North America and elsewhere. We evaluated their potential global climate suitability for cultivation and potential invasion using the niche model CLIMEX and evaluated the models' sensitivity to the parameter values. We then compared the sensitivity of projections of future climatically suitable area under two climate models and two emissions scenarios. The models indicate that the species have been introduced to most of the potential global climatically suitable areas in the northern but not the southern hemisphere. The more narrowly distributed species (M. sacchariflorus) is more sensitive to changes in model parameters, which could have implications for modelling species of conservation concern. Climate projections indicate likely contractions in potential range in the south, but expansions in the north, particularly in introduced areas where biomass production trials are under way. Climate sensitivity analysis shows that projections differ more between the selected climate change models than between the selected emissions scenarios. Local-scale assessments are required to overlay suitable habitat with climate projections to estimate areas of cultivation potential and invasion risk.

  13. Predicting potential global distributions of two Miscanthus grasses: implications for horticulture, biofuel production, and biological invasions.

    Directory of Open Access Journals (Sweden)

    Heather A Hager

    Full Text Available In many regions, large proportions of the naturalized and invasive non-native floras were originally introduced deliberately by humans. Pest risk assessments are now used in many jurisdictions to regulate the importation of species and usually include an estimation of the potential distribution in the import area. Two species of Asian grass (Miscanthus sacchariflorus and M. sinensis that were originally introduced to North America as ornamental plants have since escaped cultivation. These species and their hybrid offspring are now receiving attention for large-scale production as biofuel crops in North America and elsewhere. We evaluated their potential global climate suitability for cultivation and potential invasion using the niche model CLIMEX and evaluated the models' sensitivity to the parameter values. We then compared the sensitivity of projections of future climatically suitable area under two climate models and two emissions scenarios. The models indicate that the species have been introduced to most of the potential global climatically suitable areas in the northern but not the southern hemisphere. The more narrowly distributed species (M. sacchariflorus is more sensitive to changes in model parameters, which could have implications for modelling species of conservation concern. Climate projections indicate likely contractions in potential range in the south, but expansions in the north, particularly in introduced areas where biomass production trials are under way. Climate sensitivity analysis shows that projections differ more between the selected climate change models than between the selected emissions scenarios. Local-scale assessments are required to overlay suitable habitat with climate projections to estimate areas of cultivation potential and invasion risk.

  14. Whisking-Related Changes in Neuronal Firing and Membrane Potential Dynamics in the Somatosensory Thalamus of Awake Mice

    Directory of Open Access Journals (Sweden)

    Nadia Urbain

    2015-10-01

    Full Text Available The thalamus transmits sensory information to the neocortex and receives neocortical, subcortical, and neuromodulatory inputs. Despite its obvious importance, surprisingly little is known about thalamic function in awake animals. Here, using intracellular and extracellular recordings in awake head-restrained mice, we investigate membrane potential dynamics and action potential firing in the two major thalamic nuclei related to whisker sensation, the ventral posterior medial nucleus (VPM and the posterior medial group (Pom, which receive distinct inputs from brainstem and neocortex. We find heterogeneous state-dependent dynamics in both nuclei, with an overall increase in action potential firing during active states. Whisking increased putative lemniscal and corticothalamic excitatory inputs onto VPM and Pom neurons, respectively. A subpopulation of VPM cells fired spikes phase-locked to the whisking cycle during free whisking, and these cells may therefore signal whisker position. Our results suggest differential processing of whisking comparing thalamic nuclei at both sub- and supra-threshold levels.

  15. Mechanisms of radiation interaction with DNA: Potential implications for radiation protection

    International Nuclear Information System (INIS)

    Sinclair, W.K.; Fry, R.J.M.

    1987-01-01

    An overview of presentations and discussions which took place at the US Department of Energy/Commission of European Communities (DOE/CEC) workshop on ''Mechanisms of Radiation Interaction with DNA: Potential Implications for Radiation Protection,'' held at San Diego, California, January 21-22, 1987, is provided. The Department has traditionally supported fundamental research on interactions of ionizing radiation with different biological systems and at all levels of biological organization. The aim of this workshop was to review the base of knowledge in the area of mechanisms of radiation action at the DNA level, and to explore ways in which this information can be applied to the development of scientifically sound concepts and procedures for use in the field of radiation protection

  16. China as an Arctic Great Power. Potential Implications for Greenland and the Danish Realm

    DEFF Research Database (Denmark)

    Nørup Sørensen, Camilla Tenna

    In late January 2018, China released its long-awaited White Paper on China’s Arctic Policy. It represents the culmination of the development of a more confident, proactive and sophisticated Chinese diplomacy in the Arctic and reflects how the Arctic has moved up the Chinese leaders’ foreign...... and security policy agenda and is assigned increasing strategic significance. The policy brief analyses China’s Arctic White Paper focusing on the potential implications for Greenland and the Danish Realm. The policy brief concludes that China’s increasing presence in the Arctic constitutes a challenge as well...... as an opportunity depending on whether Copenhagen and Nuuk are able to find stronger common ground in their approach to China in the Arctic and succeed in establishing open, respectful and constructive dialogue and cooperation on this matter....

  17. Student's corner: potential implications of registered nurse attitudes towards caring for older people.

    Science.gov (United States)

    Marshall, Lynette C

    2010-01-01

    In discussing the potential implications of the attitudes of the registered nurse towards the work of caring for older people, it was helpful to highlight why this work is important, gain some understanding of quality care and how it can be facilitated or hindered. Patient centred care is essential as there is great diversity found amongst older people. It was found that attitudes held by registered nurses and students towards older people have a direct impact on the quality of care provided. Negative attitudes and stereotyping get in the way of quality care while positive attitudes enabled quality care. In identifying the factors that influence these attitudes, registered nurses can take on a leadership role in promoting positive attitudes and challenging negative attitudes towards the care of older people with the goal of providing patient centre care.

  18. Potential implications for expansion of freeze-tolerant eucalyptus plantations on water resources in the southern United States

    Science.gov (United States)

    James M. Vose; Chelcy F. Miniat; Ge Sun; Peter V. Caldwell

    2014-01-01

    The potential expansion of freeze-tolerant (FT) Eucalyptus plantations in the United States has raised concerns about the implications for water resources. Modeling was used to examine the potential effects of expanding the distribution of FT Eucalyptus plantations in US Department of Agriculture Plant Hardiness Zones 8b and...

  19. Measuring the strength of interaction between the Ebola fusion peptide and lipid rafts: implications for membrane fusion and virus infection.

    Directory of Open Access Journals (Sweden)

    Mônica S Freitas

    Full Text Available The Ebola fusion peptide (EBO₁₆ is a hydrophobic domain that belongs to the GP2 membrane fusion protein of the Ebola virus. It adopts a helical structure in the presence of mimetic membranes that is stabilized by the presence of an aromatic-aromatic interaction established by Trp8 and Phe12. In spite of its infectious cycle becoming better understood recently, several steps still remain unclear, a lacuna that makes it difficult to develop strategies to block infection. In order to gain insight into the mechanism of membrane fusion, we probed the structure, function and energetics of EBO₁₆ and its mutant W8A, in the absence or presence of different lipid membranes, including isolated domain-resistant membranes (DRM, a good experimental model for lipid rafts. The depletion of cholesterol from living mammalian cells reduced the ability of EBO₁₆ to induce lipid mixing. On the other hand, EBO₁₆ was structurally sensitive to interaction with lipid rafts (DRMs, but the same was not observed for W8A mutant. In agreement with these data, W8A showed a poor ability to promote membrane aggregation in comparison to EBO₁₆. Single molecule AFM experiments showed a high affinity force pattern for the interaction of EBO₁₆ and DRM, which seems to be a complex energetic event as observed by the calorimetric profile. Our study is the first to show a strong correlation between the initial step of Ebola virus infection and cholesterol, thus providing a rationale for Ebola virus proteins being co-localized with lipid-raft domains. In all, the results show how small fusion peptide sequences have evolved to adopt highly specific and strong interactions with membrane domains. Such features suggest these processes are excellent targets for therapeutic and vaccine approaches to viral diseases.

  20. Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications.

    Science.gov (United States)

    Nánási, Péter P; Magyar, János; Varró, András; Ördög, Balázs

    2017-10-01

    Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by I Ca , I Kr , and I Ks while increased by I Na , suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.

  1. Potential environmental implications of nanoscale zero-valent iron particles for environmental remediation

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    Min-Hee Jang

    2014-12-01

    Full Text Available Objectives Nanoscale zero-valent iron (nZVI particles are widely used in the field of various environmental contaminant remediation. Although the potential benefits of nZVI are considerable, there is a distinct need to identify any potential risks after environmental exposure. In this respect, we review recent studies on the environmental applications and implications of nZVI, highlighting research gaps and suggesting future research directions. Methods Environmental application of nZVI is briefly summarized, focusing on its unique properties. Ecotoxicity of nZVI is reviewed according to type of organism, including bacteria, terrestrial organisms, and aquatic organisms. The environmental fate and transport of nZVI are also summarized with regards to exposure scenarios. Finally, the current limitations of risk determination are thoroughly provided. Results The ecotoxicity of nZVI depends on the composition, concentration, size and surface properties of the nanoparticles and the experimental method used, including the species investigated. In addition, the environmental fate and transport of nZVI appear to be complex and depend on the exposure duration and the exposure conditions. To date, field-scale data are limited and only short-term studies using simple exposure methods have been conducted. Conclusions In this regard, the primary focus of future study should be on 1 the development of an appropriate and valid testing method of the environmental fate and ecotoxicity of reactive nanoparticles used in environmental applications and 2 assessing their potential environmental risks using in situ field scale applications.

  2. 'Underutilised' agricultural land: its definitions, potential use for future biomass production and its environmental implications

    Science.gov (United States)

    Miyake, Saori; Bargiel, Damian

    2017-04-01

    A growing bioeconomy and increased demand for biomass products on food, health, fibre, industrial products and energy require land resources for feedstock production. It has resulted in significant environmental and socio-economic challenges on a global scale. As a result, consideration of such effects of land use change (LUC) from biomass production (particularly for biofuel feedstock) has emerged as an important area of policy and research, and several potential solutions have been proposed to minimise such adverse LUC effects. One of these solutions is the use of lands that are not in production or not suitable for food crop production, such as 'marginal', 'degraded', 'abandoned' and 'surplus' agricultural lands for future biomass production. The terms referring to these lands are usually associated with the potential production of 'marginal crops', which can grow in marginal conditions (e.g. poor soil fertility, low rainfall, drought) without much water and agrochemical inputs. In our research, we referred to these lands as 'underutilised' agricultural land and attempted to define them for our case study areas located in Australia and Central and Eastern Europe (CEE). Our goal is to identify lands that can be used for future biomass production and to evaluate their environmental implications, particularly impacts related to biodiversity, water and soil at a landscape scale. The identification of these lands incorporates remote sensing and spatially explicit approaches. Our findings confirmed that there was no universal or single definition of the term 'underutilised' agricultural land as the definitions significantly vary by country and region depending not only on the biophysical environment but also political, institutional and socio-economic conditions. Moreover, our results highlighted that the environmental implications of production of biomass on 'underutilised' agricultural land for biomass production are highly controversial. Thus land use change

  3. Potential contact and intraocular lenses based on hydrophilic/hydrophobic sulfonated syndiotactic polystyrene membranes

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    Simona Zuppolini

    2017-10-01

    Full Text Available Crystalline films of syndiotactic polystyrene (s-PS, a commercially available thermoplastic polymer, having a highly hydrophilic amorphous phase, were achieved by using a mild solid-state sulfonation procedure. Despite the used mild process conditions, an easy and uniform sulfonation of the phenyl rings of the amorphous phase is obtained. The crystallinity of the polymer was not affect by the sulfonation degree (S, at least at S less than 20%, and the obtained polymer films show the nanoporous crystalline form of s-PS. As widely reported in literature, the nanoporous nature of the polymer crystalline phase gives to these materials the ability to absorb and release organic molecules of appropriate size and polarity. This property, coupled to transparency, makes these materials potentially useful intraocular lens (IOLs and contact lens applications. Sulfonation procedure and sulfonated film samples characterization by using wide-angle X-ray diffraction (WAXD, Fourier-transform infrared (FTIR and ultraviolet-visible (UV-vis spectroscopy techniques and water sorption tests were reported. Furthermore, the biocompatibility study demonstrated no cytotoxicity and appropriate cell interaction properties for the specific applications.

  4. Dynamics of membrane potential variation and gene expression induced by Spodoptera littoralis, Myzus persicae, and Pseudomonas syringae in Arabidopsis.

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    Irene Bricchi

    Full Text Available BACKGROUND: Biotic stress induced by various herbivores and pathogens invokes plant responses involving different defense mechanisms. However, we do not know whether different biotic stresses share a common response or which signaling pathways are involved in responses to different biotic stresses. We investigated the common and specific responses of Arabidopsis thaliana to three biotic stress agents: Spodoptera littoralis, Myzus persicae, and the pathogen Pseudomonas syringae. METHODOLOGY/PRINCIPAL FINDINGS: We used electrophysiology to determine the plasma membrane potential (V(m and we performed a gene microarray transcriptome analysis on Arabidopsis upon either herbivory or bacterial infection. V(m depolarization was induced by insect attack; however, the response was much more rapid to S. littoralis (30 min -2 h than to M. persicae (4-6 h. M. persicae differentially regulated almost 10-fold more genes than by S. littoralis with an opposite regulation. M. persicae modulated genes involved in flavonoid, fatty acid, hormone, drug transport and chitin metabolism. S. littoralis regulated responses to heat, transcription and ion transport. The latest Vm depolarization (16 h was found for P. syringae. The pathogen regulated responses to salicylate, jasmonate and to microorganisms. Despite this late response, the number of genes differentially regulated by P. syringae was closer to those regulated by S. littoralis than by M. persicae. CONCLUSIONS/SIGNIFICANCE: Arabidopsis plasma membranes respond with a V(m depolarization at times depending on the nature of biotic attack which allow setting a time point for comparative genome-wide analysis. A clear relationship between V(m depolarization and gene expression was found. At V(m depolarization timing, M. persicae regulates a wider array of Arabidopsis genes with a clear and distinct regulation than S. littoralis. An almost completely opposite regulation was observed between the aphid and the pathogen

  5. Stepwise reduction of the culture redox potential allows the analysis of microaerobic metabolism and photosynthetic membrane synthesis in Rhodospirillum rubrum.

    Science.gov (United States)

    Carius, Lisa; Hädicke, Oliver; Grammel, Hartmut

    2013-02-01

    Bacterial growth under oxygen-limited (microaerobic) conditions is often accompanied by phenomena of great interest for fundamental research and industrial application. The microaerobic lifestyle of anoxygenic photosynthetic bacteria like Rhodospirillum rubrum harbors such a phenomenon, as it allows the formation of photosynthetic membranes and related interesting products without light. However, due to the technical difficulties in process control of microaerobic cultivations and the limited sensitivity of available oxygen sensors, the analysis of microaerobic growth and physiology is still underrepresented in current research. The main focus of the present study was to establish an experimental set-up for the systematic study of physiological processes, associated with the growth of R. rubrum under microaerobic conditions in the dark. For this purpose, we introduce a robust and reliable microaerobic process control strategy, which applies the culture redox potential (CRP) for assessing different degrees of oxygen limitation in bioreactor cultivations. To describe the microaerobic growth behavior of R. rubrum cultures for each of these defined CRP reduction steps, basic growth parameters were experimentally determined. Flux variability analysis provided an insight into the metabolic activity of the TCA cycle and implied its connection to the respiratory capacity of the cells. In this context, our results suggest that microaerobic growth of R. rubrum can be described as an oxygen-activated cooperative mechanism. The present study thus contributes to the investigation of metabolic and regulatory events responsible for the redox-sensitive formation of photosynthetic membranes in facultative photosynthetic bacteria. Furthermore, the introduced microaerobic cultivation setup should be generally applicable for any microbial system of interest which can be cultivated in common stirred-tank bioreactors. Copyright © 2012 Wiley Periodicals, Inc.

  6. Dynamics of Membrane Potential Variation and Gene Expression Induced by Spodoptera littoralis, Myzus persicae, and Pseudomonas syringae in Arabidopsis

    Science.gov (United States)

    Bricchi, Irene; Bertea, Cinzia M.; Occhipinti, Andrea; Paponov, Ivan A.; Maffei, Massimo E.

    2012-01-01

    Background Biotic stress induced by various herbivores and pathogens invokes plant responses involving different defense mechanisms. However, we do not know whether different biotic stresses share a common response or which signaling pathways are involved in responses to different biotic stresses. We investigated the common and specific responses of Arabidopsis thaliana to three biotic stress agents: Spodoptera littoralis, Myzus persicae, and the pathogen Pseudomonas syringae. Methodology/Principal Findings We used electrophysiology to determine the plasma membrane potential (Vm) and we performed a gene microarray transcriptome analysis on Arabidopsis upon either herbivory or bacterial infection. Vm depolarization was induced by insect attack; however, the response was much more rapid to S. littoralis (30 min −2 h) than to M. persicae (4–6 h). M. persicae differentially regulated almost 10-fold more genes than by S. littoralis with an opposite regulation. M. persicae modulated genes involved in flavonoid, fatty acid, hormone, drug transport and chitin metabolism. S. littoralis regulated responses to heat, transcription and ion transport. The latest Vm depolarization (16 h) was found for P. syringae. The pathogen regulated responses to salicylate, jasmonate and to microorganisms. Despite this late response, the number of genes differentially regulated by P. syringae was closer to those regulated by S. littoralis than by M. persicae. Conclusions/Significance Arabidopsis plasma membranes respond with a Vm depolarization at times depending on the nature of biotic attack which allow setting a time point for comparative genome-wide analysis. A clear relationship between Vm depolarization and gene expression was found. At Vm depolarization timing, M. persicae regulates a wider array of Arabidopsis genes with a clear and distinct regulation than S. littoralis. An almost completely opposite regulation was observed between the aphid and the pathogen, with the former

  7. Studies on the biocidal and cell membrane disruption potentials of stem bark extracts of Afzelia africana (Smith

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    DAVID A AKINPELU

    2009-01-01

    Full Text Available We had recently reported antibacterial activity in the crude extract of the stem bark of Afzelia africana (Akinpelu et al., 2008. In this study, we assessed the biocidal and cell membrane disruption potentials of fractions obtained from the crude extract of the plant. The aqueous (AQ and butanol (BL fractions exhibited appreciable antibacterial activities against the test bacteria. The minimum inhibitory concentrations of the AQ and BL fractions ranged between 0.313 and 2.5 mg/ml, while their minimum bactericidal concentrations varied between 0.625 and 5.0 mg/ml. Also, the AQ fraction killed about 95.8% of E. coli cells within 105 min at a concentration of 5 mg/ml, while about 99.1% of Bacillus pumilus cells were killed by this fraction at the same concentration and exposure time. A similar trend was observed for the BL fraction. At a concentration of 5 mg/ml, the butanol fraction leaked 9.8 μg/ml of proteins from E. coli cells within 3 h, while the aqueous fraction leaked 6.5 μg/ml of proteins from the same organisms at the same concentration and exposure time. We propose that the stem bark of Afzelia africana is a potential source of bioactive compounds of importance to the pharmaceutical industry.

  8. Mitochondrial uncouplers act synergistically with the fumigant phosphine to disrupt mitochondrial membrane potential and cause cell death.

    Science.gov (United States)

    Valmas, Nicholas; Zuryn, Steven; Ebert, Paul R

    2008-10-30

    Phosphine is the most widely used fumigant for the protection of stored commodities against insect pests, especially food products such as grain. However, pest insects are developing resistance to phosphine and thereby threatening its future use. As phosphine inhibits cytochrome c oxidase (complex IV) of the mitochondrial respiratory chain and reduces the strength of the mitochondrial membrane potential (DeltaPsi(m)), we reasoned that mitochondrial uncouplers should act synergistically with phosphine. The mitochondrial uncouplers FCCP and PCP caused complete mortality in populations of both wild-type and phosphine-resistant lines of Caenorhabditis elegans simultaneously exposed to uncoupler and phosphine at concentrations that were individually nonlethal. Strong synergism was also observed with a third uncoupler DNP. We have also tested an alternative complex IV inhibitor, azide, with FCCP and found that this also caused a synergistic enhancement of toxicity in C. elegans. To investigate potential causes of the synergism, we measured DeltaPsi(m), ATP content, and oxidative damage (lipid hydroperoxides) in nematodes subjected to phosphine-FCCP treatment and found that neither an observed 50% depletion in ATP nor oxidative stress accounted for the synergistic effect. Instead, a synergistic reduction in DeltaPsi(m) was observed upon phosphine-FCCP co-treatment suggesting that this is directly responsible for the subsequent mortality. These results support the hypothesis that phosphine-induced mortality results from the in vivo disruption of normal mitochondrial activity. Furthermore, we have identified a novel pathway that can be targeted to overcome genetic resistance to phosphine.

  9. The potential of mesenchymal stem cells derived from amniotic membrane and amniotic fluid for neuronal regenerative therapy.

    Science.gov (United States)

    Kim, Eun Young; Lee, Kyung-Bon; Kim, Min Kyu

    2014-03-01

    The mesenchymal stem cells (MSCs), which are derived from the mesoderm, are considered as a readily available source for tissue engineering. They have multipotent differentiation capacity and can be differentiated into various cell types. Many studies have demonstrated that the MSCs identified from amniotic membrane (AM-MSCs) and amniotic fluid (AF-MSCs) are shows advantages for many reasons, including the possibility of noninvasive isolation, multipotency, self-renewal, low immunogenicity, anti-inflammatory and nontumorigenicity properties, and minimal ethical problem. The AF-MSCs and AM-MSCs may be appropriate sources of mesenchymal stem cells for regenerative medicine, as an alternative to embryonic stem cells (ESCs). Recently, regenerative treatments such as tissue engineering and cell transplantation have shown potential in clinical applications for degenerative diseases. Therefore, amnion and MSCs derived from amnion can be applied to cell therapy in neuro-degeneration diseases. In this review, we will describe the potential of AM-MSCs and AF-MSCs, with particular focus on cures for neuronal degenerative diseases.

  10. Membrane testosterone binding sites in prostate carcinoma as a potential new marker and therapeutic target: Study in paraffin tissue sections

    International Nuclear Information System (INIS)

    Dambaki, Constantina; Kogia, Christina; Kampa, Marilena; Darivianaki, Katherine; Nomikos, Michael; Anezinis, Ploutarchos; Theodoropoulos, Panayiotis A; Castanas, Elias; Stathopoulos, Efstathios N

    2005-01-01

    Steroid action is mediated, in addition to classical intracellular receptors, by recently identified membrane sites, that generate rapid non-genomic effects. We have recently identified a membrane androgen receptor site on prostate carcinoma cells, mediating testosterone rapid effects on the cytoskeleton and secretion within minutes. The aim of this study was to investigate whether membrane androgen receptors are differentially expressed in prostate carcinomas, and their relationship to the tumor grade. We examined the expression of membrane androgen receptors in archival material of 109 prostate carcinomas and 103 benign prostate hyperplasias, using fluorescein-labeled BSA-coupled testosterone. We report that membrane androgen receptors are preferentially expressed in prostate carcinomas, and they correlate to their grade using the Gleason's microscopic grading score system. We conclude that membrane androgen receptors may represent an index of tumor aggressiveness and possibly specific targets for new therapeutic regimens

  11. Ultrasmall Peptides Self-Assemble into Diverse Nanostructures: Morphological Evaluation and Potential Implications

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    Charlotte A.E. Hauser

    2011-09-01

    Full Text Available In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures.

  12. Mechanics and dynamics of triglyceride-phospholipid model membranes

    DEFF Research Database (Denmark)

    Pakkanen, Kirsi I.; Duelund, Lars; Qvortrup, Klaus

    2011-01-01

    We demonstrate here that triolein alters the mechanical properties of phospholipid membranes and induces extraordinary conformational dynamics. Triolein containing membranes exhibit fluctuations up to size range of 100µm and with the help of these are e.g. able to squeeze through narrow passages...... with larger lamellar distances observed in the TOPOPC membranes. These findings suggest repulsion between adjacent membranes. We provide a comprehensive discussion on the possible explanations for the observed mechanics and dynamics in the TOPOPC system and on their potential cellular implications....

  13. Mesenchymal Stem Cells and Metabolic Syndrome: Current Understanding and Potential Clinical Implications

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    Kenichi Matsushita

    2016-01-01

    Full Text Available Metabolic syndrome is an obesity-based, complicated clinical condition that has become a global epidemic problem with a high associated risk for cardiovascular disease and mortality. Dyslipidemia, hypertension, and diabetes or glucose dysmetabolism are the major factors constituting metabolic syndrome, and these factors are interrelated and share underlying pathophysiological mechanisms. Severe obesity predisposes individuals to metabolic syndrome, and recent data suggest that mesenchymal stem cells (MSCs contribute significantly to adipocyte generation by increasing the number of adipocytes. Accordingly, an increasing number of studies have examined the potential roles of MSCs in managing obesity and metabolic syndrome. However, despite the growing bank of experimental and clinical data, the efficacy and the safety of MSCs in the clinical setting are still to be optimized. It is thus hoped that ongoing and future studies can elucidate the roles of MSCs in metabolic syndrome and lead to MSC-based therapeutic options for affected patients. This review discusses current understanding of the relationship between MSCs and metabolic syndrome and its potential implications for patient management.

  14. Nonribosomal peptides and polyketides of Burkholderia: new compounds potentially implicated in biocontrol and pharmaceuticals.

    Science.gov (United States)

    Esmaeel, Qassim; Pupin, Maude; Jacques, Philippe; Leclère, Valérie

    2017-05-25

    Bacteria belonging to the genus Burkholderia live in various ecological niches and present a significant role in the environments through the excretion of a wide variety of secondary metabolites including modular nonribosomal peptides (NRPs) and polyketides (PKs). These metabolites represent a widely distributed biomedically and biocontrol important class of natural products including antibiotics, siderophores, and anticancers as well as biopesticides that are considered as a novel source that can be used to defend ecological niche from competitors and to promote plant growth. The aim of this review is to present all NRPs produced or potentially produced by strains of Burkholderia, as NRPs represent a major source of active compounds implicated in biocontrol. The review is a compilation of results from a large screening we have performed on 48 complete sequenced genomes available in NCBI to identify NRPS gene clusters, and data found in the literature mainly because some interesting compounds are produced by strains not yet sequenced. In addition to NRPs, hybrids NRPs/PKs are also included. Specific features about biosynthetic gene clusters and structures of the modular enzymes responsible for the synthesis, the biological activities, and the potential uses in agriculture and pharmaceutical of NRPs and hybrids NRPs/PKs will also be discussed.

  15. Membrane potential of cells and its regulation during aging. 2. Report: the effect of hormones on the level of the cellular plasma membrane polarization.

    Science.gov (United States)

    Frolkis, V V; Tanin, S A; Gorban, E N; Bogatskaya, L N; Sabko, V E

    1987-01-01

    Age-dependent changes in the polarization of plasma membranes (PM) of various cell types and the mechanisms responsible for its regulation were studied in the experiments on the adult (6-8 and old (28-32 months) Wistar male rats. It was found that the effect of the hormones on the PM polarization level is altered during aging. This being related to shifts in the number and affinity of the hormonal receptors, energetic processes and protein synthesis in the cell.

  16. Glucose sensing by carotid body glomus cells: potential implications in disease

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    Lin eGao

    2014-10-01

    Full Text Available The carotid body (CB is a key chemoreceptor organ in which glomus cells sense changes in blood O2, CO2, and pH levels. CB glomus cells have also been found to detect hypoglycemia in both non-primate mammals and humans. O2 and low-glucose responses share a common final pathway involving membrane depolarization, extracellular calcium influx, increase in cytosolic calcium concentration, and neurotransmitter secretion, which stimulates afferent sensory fibers to evoke sympathoadrenal activation. On the other hand, hypoxia and low glucose induce separate signal transduction pathways. Unlike O2 sensing, the response of the CB to low glucose is not altered by rotenone, with the low glucose-activated background cationic current unaffected by hypoxia. Responses of the CB to hypoglycemia and hypoxia can be potentiated by each other. The counter-regulatory response to hypoglycemia by the CB is essential for the brain, an organ that is particularly sensitive to low glucose. CB glucose sensing could be altered in diabetic patients, particularly those under insulin treatment, as well as in other medical conditions such as sleep apnea or obstructive pulmonary diseases, where chronic hypoxemia presents with plastic modifications in CB structure and function. The current review will focus on the following main aspects: 1 the CB as a low glucose sensor in both in vitro and in vivo models; 2 molecular and ionic mechanisms of low glucose sensing by glomus cells, 3 the interplay between low glucose and O2 sensing in CB, and 4 the role of CB low glucose sensing in the pathophysiology of cardiorespiratory and metabolic diseases, and how this may serve as a potential therapeutic target.

  17. Relative mitochondrial membrane potential and [Ca2+]i in type I cells isolated from the rabbit carotid body.

    Science.gov (United States)

    Duchen, M R; Biscoe, T J

    1992-05-01

    1. In the accompanying paper (Duchen & Biscoe, 1992) we have described graded changes in autofluorescence derived from mitochondrial NAD(P)H in type I cells of the carotid body in response to changes of PO2 over a physiologically significant range. These observations suggest that mitochondrial function in these cells is unusually sensitive to oxygen and could play a role in oxygen sensing. We have now explored further the relationships between hypoxia, mitochondrial membrane potential (delta psi m) and [Ca2+]i. 2. The fluorescence of Rhodamine 123 (Rh 123) accumulated within mitochondria is quenched by delta psi m. Mitochondrial depolarization thus increases the fluorescence signal. Blockade of electron transport (CN-, anoxia, rotenone) and uncoupling agents (e.g. carbonyl cyanide p-trifluoromethoxy-phenylhydrazone; FCCP) increased fluorescence by up to 80-120%, while fluorescence was reduced by blockade of the F0 proton channel of the mitochondrial ATP synthase complex (oligomycin). 3. delta psi m depolarized rapidly with anoxia, and was usually completely dissipated within 1-2 min. The depolarization of delta psi m with anoxia (or CN-) and repolarization on reoxygenation both followed a time course well characterized as the sum of two exponential processes. Oligomycin (0.2-2 micrograms/ml) hyperpolarized delta psi m and abolished the slower components of both the depolarization with anoxia and of the subsequent repolarization. These data (i) illustrate the role of the F1-F0 ATP synthetase in slowing the rate of dissipation of delta psi m on cessation of electron transport, (ii) confirm blockade of the ATP synthetase by oligomycin at these concentrations, and (iii) indicate significant accumulation of intramitochondrial ADP during 1-2 min of anoxia. 4. Depolarization of delta psi m was graded with graded changes in PO2 below about 60 mmHg. The stimulus-response curves thus constructed strongly resemble those for [Ca2+]i and NAD(P)H with PO2. The change in delta

  18. Effects of the gliotoxin fluorocitrate on spreading depression and glial membrane potential in rat brain in situ.

    Science.gov (United States)

    Largo, C; Ibarz, J M; Herreras, O

    1997-07-01

    DC extracellular potential shifts (deltaVo) associated with spreading depression (SD) reflect massive cell depolarization, but their cellular generators remain obscure. We have recently reported that the glial specific metabolic poison fluorocitrate (FC) delivered by microdialysis in situ caused a rapid impairment of glial function followed some hours later by loss of neuronal electrogenic activity and neuron death. We have used the time windows for selective decay of cell types so created to study the relative participation of glia and neurons in SD, and we report a detailed analysis of the effects of FC on evoked SD waves and glial membrane potential (Vm). Extracellular potential (Vo), interstitial potassium concentration ([K+]o), evoked potentials, and transmembrane glial potentials were monitored in the CA1 area before, during, and after administration of FC with or without elevated K+ concentration in the dialysate. SD waves propagated faster and lasted longer during FC treatment. DeltaVo in stratum pyramidale, which normally are much shorter and of smaller amplitude than those in stratum radiatum, expanded during FC treatment to match those in stratum radiatum. The coalescing SD waves that develop late during prolonged high-K+ dialysis and are typically limited to stratum radiatum, also expanded into stratum pyramidale under the influence of FC. SD provoked in neocortex normally does not spread to the CA1, but during FC treatment it readily reached CA1 via entorhinal cortex. Once neuronal function began to deteriorate, SD waves became smaller and slower, and eventually failed to enter the region around the FC source. Slow, moderately negative deltaVo that mirrored [K+]o increments could still be recorded well after neuronal function and SD-associated Vo had disappeared. Glial cell Vm gradually depolarized during FC administration, beginning much before depression of neuronal antidromic action potentials. Calculations based on the results predict a large

  19. Aging Yeast Cells Undergo a Sharp Entry into Senescence Unrelated to the Loss of Mitochondrial Membrane Potential

    Directory of Open Access Journals (Sweden)

    Steffen Fehrmann

    2013-12-01

    Full Text Available In budding yeast, a mother cell can produce a finite number of daughter cells before it stops dividing and dies. Such entry into senescence is thought to result from a progressive decline in physiological function, including a loss of mitochondrial membrane potential (ΔΨ. Here, we developed a microfluidic device to monitor the dynamics of cell division and ΔΨ in real time at single-cell resolution. We show that cells do not enter senescence gradually but rather undergo an abrupt transition to a slowly dividing state. Moreover, we demonstrate that the decline in ΔΨ, which is observed only in a fraction of cells, is not responsible for entry into senescence. Rather, the loss of ΔΨ is an age-independent and heritable process that leads to clonal senescence and is therefore incompatible with daughter cell rejuvenation. These results emphasize the importance of quantitative single-cell measurements to decipher the causes of cellular aging.

  20. Silica Induces Changes in Cytosolic Free Calcium, Cytosolic pH, and Plasma Membrane Potential in Bovine Alveolar Macrophages

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    Attila Tárnok

    1997-01-01

    Full Text Available The mineral‐dust induced activation of pulmonary phagocytes is thought to be involved in the induction of severe lung diseases. The activation of bovine alveolar macrophages (BAM by silica was investigated by flow cytometry. Short‐term incubation (10 min of BAM with silica gel and quartz dust particles induced increases in the cytosolic free calcium concentration ([Ca2+]i, decreases in intracellular pH (pHi, and increases in plasma membrane potential (PMP. The extent of these changes was concentration dependent, related to the type of dust and was due to Ca2+ influx from the extracellular medium. An increase in [Ca2+]i was inhibited, when extracellular Ca2+ was removed. Furthermore the calcium signal was quenched by Mn2+ and diminished by the calcium channel blocker verapamil. The protein kinase C specific inhibitor bisindolylmaleimide II (GF 109203 X did not inhibit the silica‐induced [Ca2+]i rise. In contrast, silica‐induced cytosolic acidification and depolarization were inhibited by GF 109203 X but not by removal of extracellular calcium. Addition of TiO2 particles or heavy metal‐containing dusts had no effect on any of the three parameters. Our data suggest the existence of silica‐activated transmembrane ion exchange mechanisms in BAM, which might be involved in the specific cytotoxicity of silica by Ca2+‐dependent and independent pathways.

  1. Potential Usage of Thermoelectric Devices in a High-Temperature Polymer Electrolyte Membrane (PEM) Fuel Cell System: Two Case Studies

    Science.gov (United States)

    Gao, Xin; Chen, Min; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2012-06-01

    Methanol-fueled, high-temperature polymer electrolyte membrane fuel cell (HTPEMFC) power systems are promising as the next generation of vehicle engines, efficient and environmentally friendly. Currently, their performance still needs to be improved, and they still rely on a large Li-ion battery for system startup. In this article, to handle these two issues, the potential of thermoelectric (TE) devices applied in a HTPEMFC power system has been preliminarily evaluated. First, right after the fuel cell stack or the methanol reformer, thermoelectric generators (TEGs) are embedded inside a gas-liquid heat exchanger to form a heat recovery subsystem jointly for electricity production. It is calculated that the recovered power can increase the system efficiency and mitigate the dependence on Li-ion battery during system startup. To improve the TEG subsystem performance, a finite-difference model is then employed and two main parameters are identified. Second, TE coolers are integrated into the methanol steam reformer to regulate heat fluxes herein and improve the system dynamic performance. Similar modification is also done on the evaporator to improve its dynamic performance as well as to reduce the heat loss during system startup. The results demonstrate that the TE-assisted heat flux regulation and heat-loss reduction can also effectively help solve the abovementioned two issues. The preliminary analysis in this article shows that a TE device application inside HTPEMFC power systems is of great value and worthy of further study.

  2. Mitochondrial membrane potential in human neutrophils is maintained by complex III activity in the absence of supercomplex organisation.

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    Bram J van Raam

    Full Text Available BACKGROUND: Neutrophils depend mainly on glycolysis for their energy provision. Their mitochondria maintain a membrane potential (Deltapsi(m, which is usually generated by the respiratory chain complexes. We investigated the source of Deltapsi(m in neutrophils, as compared to peripheral blood mononuclear leukocytes and HL-60 cells, and whether neutrophils can still utilise this Deltapsi(m for the generation of ATP. METHODS AND PRINCIPAL FINDINGS: Individual activity of the oxidative phosphorylation complexes was significantly reduced in neutrophils, except for complex II and V, but Deltapsi(m was still decreased by inhibition of complex III, confirming the role of the respiratory chain in maintaining Deltapsi(m. Complex V did not maintain Deltapsi(m by consumption of ATP, as has previously been suggested for eosinophils. We show that complex III in neutrophil mitochondria can receive electrons from glycolysis via the glycerol-3-phosphate shuttle. Furthermore, respiratory supercomplexes, which contribute to efficient coupling of the respiratory chain to ATP synthesis, were lacking in neutrophil mitochondria. When HL-60 cells were differentiated to neutrophil-like cells, they lost mitochondrial supercomplex organisation while gaining increased aerobic glycolysis, just like neutrophils. CONCLUSIONS: We show that neutrophils can maintain Deltapsi(m via the glycerol-3-phosphate shuttle, whereby their mitochondria play an important role in the regulation of aerobic glycolysis, rather than producing energy themselves. This peculiar mitochondrial phenotype is acquired during differentiation from myeloid precursors.

  3. Pantothenate kinase-associated neurodegeneration: altered mitochondria membrane potential and defective respiration in Pank2 knock-out mouse model.

    Science.gov (United States)

    Brunetti, Dario; Dusi, Sabrina; Morbin, Michela; Uggetti, Andrea; Moda, Fabio; D'Amato, Ilaria; Giordano, Carla; d'Amati, Giulia; Cozzi, Anna; Levi, Sonia; Hayflick, Susan; Tiranti, Valeria

    2012-12-15

    Neurodegeneration with brain iron accumulation (NBIA) comprises a group of neurodegenerative disorders characterized by high brain content of iron and presence of axonal spheroids. Mutations in the PANK2 gene, which encodes pantothenate kinase 2, underlie an autosomal recessive inborn error of coenzyme A metabolism, called pantothenate kinase-associated neurodegeneration (PKAN). PKAN is characterized by dystonia, dysarthria, rigidity and pigmentary retinal degeneration. The pathogenesis of this disorder is poorly understood and, although PANK2 is a mitochondrial protein, perturbations in mitochondrial bioenergetics have not been reported. A knock-out (KO) mouse model of PKAN exhibits retinal degeneration and azoospermia, but lacks any neurological phenotype. The absence of a clinical phenotype has partially been explained by the different cellular localization of the human and murine PANK2 proteins. Here we demonstrate that the mouse Pank2 protein localizes to mitochondria, similar to its human orthologue. Moreover, we show that Pank2-defective neurons derived from KO mice have an altered mitochondrial membrane potential, a defect further corroborated by the observations of swollen mitochondria at the ultra-structural level and by the presence of defective respiration.

  4. Pressure-induced basilar membrane position shifts and the stimulus-evoked potentials in the low-frequency region of the guinea pig cochlea

    NARCIS (Netherlands)

    Fridberger, A; vanMaarseveen, JTPW; Scarfone, E; Ulfendahl, M; Flock, B; Flock, A

    1997-01-01

    We have used the guinea pig isolated temporal bone preparation to investigate changes in the nonlinear properties of the tone-evoked cochlear potentials during reversible step displacements of the basilar membrane towards either the scala tympani or the scala vestibuli. The position shifts were

  5. Impact of the growth phase on the activity of multidrug resistance pumps and membrane potential of S.cerevidiae: effect of pump overproduction and carbon source

    Czech Academy of Sciences Publication Activity Database

    Čadek, R.; Chládková, K.; Sigler, Karel; Gášková, D.

    2004-01-01

    Roč. 1665, - (2004), s. 111-117 ISSN 0005-2736 R&D Projects: GA AV ČR IBS5020202 Institutional research plan: CEZ:AV0Z5020903 Keywords : growth phases * s.cerevisiae * membrane potential Subject RIV: EE - Microbiology, Virology Impact factor: 3.441, year: 2004

  6. Neuronal excitation and permeabilization by 200-ns pulsed electric field: An optical membrane potential study with FluoVolt dye.

    Science.gov (United States)

    Pakhomov, Andrei G; Semenov, Iurii; Casciola, Maura; Xiao, Shu

    2017-07-01

    Electric field pulses of nano- and picosecond duration are a novel modality for neurostimulation, activation of Ca 2+ signaling, and tissue ablation. However it is not known how such brief pulses activate voltage-gated ion channels. We studied excitation and electroporation of hippocampal neurons by 200-ns pulsed electric field (nsPEF), by means of time-lapse imaging of the optical membrane potential (OMP) with FluoVolt dye. Electroporation abruptly shifted OMP to a more depolarized level, which was reached within 10s), so cells remained above the resting OMP level for at least 20-30s. Activation of voltage-gated sodium channels (VGSC) enhanced the depolarizing effect of electroporation, resulting in an additional tetrodotoxin-sensitive OMP peak in 4-5ms after nsPEF. Omitting Ca 2+ in the extracellular solution did not reduce the depolarization, suggesting no contribution of voltage-gated calcium channels (VGCC). In 40% of neurons, nsPEF triggered a single action potential (AP), with the median threshold of 3kV/cm (range: 1.9-4kV/cm); no APs could be evoked by stimuli below the electroporation threshold (1.5-1.9kV/cm). VGSC opening could already be detected in 0.5ms after nsPEF, which is too fast to be mediated by the depolarizing effect of electroporation. The overlap of electroporation and AP thresholds does not necessarily reflect the causal relation, but suggests a low potency of nsPEF, as compared to conventional electrostimulation, for VGSC activation and AP induction. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Characterization of thyroid hormone effects on Na-K pump and membrane potential of cultured rat skeletal myotubes

    International Nuclear Information System (INIS)

    Brodie, C.; Sampson, S.R.

    1988-01-01

    The purpose of this study was to characterize the effects of thyroid hormone on the Na-K pump and resting membrane potential (EM) of rat skeletal myotubes in culture. Myotubes were obtained from fetal (19-21 day) or neonatal rats (1-2 day) by serial trypsinization and maintained in culture for up to 10 days. Cells were treated with T4 or T3 on day 6 or 7, and measurements were made of EM, [ 3 H]ouabain binding, and ouabain-sensitive 86 Rb uptake at various times thereafter. Hormone treatment increased the values of all three variables within 24 h, plateau levels being attained by 48-72 h. Cycloheximide and actinomycin D totally blocked the effects of thyroid hormone when added together to the cells, thus suggesting that protein synthesis is necessary for the effects of these hormones. Scatchard analysis showed that the new receptors have lower ouabain affinity than those in control. Blockade of spontaneously occurring action potentials with tetrodotoxin, which blocks voltage-dependent Na channels, or Na/H antiporter with amiloride, abolished the hormone effects seen after 24 h and significantly reduced those obtained after 48 h of hormone treatment. The results demonstrate that thyroid hormone-induced increased amount and activity of the electrogenic Na-K pump in cultured myotubes occurs, at least in part, in response to an initial effect to increase Na influx. Moreover, the findings are consistent with the concept that the Na-K pump plays an important role in regulation of EM in this preparation

  8. Radiation-induced bystander effect: The important part of ionizing radiation response. Potential clinical implications

    Directory of Open Access Journals (Sweden)

    Maria Wideł

    2009-08-01

    Full Text Available It has long been a central radiobiological dogma that the damaging effects of ionizing radiation, such as cell death, cytogenetic changes, apoptosis, mutagenesis, and carcinogenesis, are the results of the direct ionization of cell structures, particularly DNA, or indirect damage via water radiolysis products. However, several years ago attention turned to a third mechanism of radiation, termed the “bystander effect” or “radiation-induced bystander effect” (RIBE. This is induced by agents and signals emitted by directly irradiated cells and manifests as a lowering of survival, cytogenetic damage, apoptosis enhancement, and biochemical changes in neighboring non-irradiated cells. The bystander effect is mainly observed in in vitro experiments using very low doses of alpha particles (range; mGy, cGy, but also after conventional irradiation (X-rays, gamma rays at low as well as conventional doses. The mechanisms responsible for the bystander effect are complex and still poorly understood. It is believed that molecular signals released from irradiated cells induce different signaling ways in non-irradiated neighboring cells, leading to the observed events. The molecular signals may be transmitted through gap junction intercellular communication and through a medium transfer mechanism. The nature of these transmitted factors are diverse, and still not defi nitely established. It seems that RIBE may have important clinical implications for health risk associated with radiation exposure. Potentially, this effectmay have important implications in the creation of whole-body or localized side effects in tissues beyond the irradiation fi eld and also in low-dose radiological and radioisotope diagnostics. Factors emitted by irradiated cells may result in the risk of genetic instability, mutations, and second primary cancer induction. They might also have their own part in inducing and extending post-radiation side effects in normal tissue. The

  9. Effects of Hypoxia on Erythrocyte Membrane Properties—Implications for Intravascular Hemolysis and Purinergic Control of Blood Flow

    Directory of Open Access Journals (Sweden)

    Ryszard Grygorczyk

    2017-12-01

    Full Text Available Intravascular hemolysis occurs in hereditary, acquired, and iatrogenic hemolytic conditions but it could be also a normal physiological process contributing to intercellular signaling. New evidence suggests that intravascular hemolysis and the associated release of adenosine triphosphate (ATP may be an important mechanism for in vivo local purinergic signaling and blood flow regulation during exercise and hypoxia. However, the mechanisms that modulate hypoxia-induced RBC membrane fragility remain unclear. Here, we provide an overview of the role of RBC ATP release in the regulation of vascular tone and prevailing assumptions on the putative release mechanisms. We show importance of intravascular hemolysis as a source of ATP for local purinergic regulation of blood flow and discuss processes that regulate membrane propensity to rupture under stress and hypoxia.

  10. Plant selenium hyperaccumulation- Ecological effects and potential implications for selenium cycling and community structure.

    Science.gov (United States)

    Reynolds, R Jason B; Pilon-Smits, Elizabeth A H

    2018-04-25

    Selenium (Se) hyperaccumulation occurs in ~50 plant taxa native to seleniferous soils in Western USA. Hyperaccumulator tissue Se levels, 1000-15,000 mg/kg dry weight, are typically 100 times higher than surrounding vegetation. Relative to other species, hyperaccumulators also transform Se more into organic forms. We review abiotic and biotic factors influencing soil Se distribution and bioavailability, soil being the source of the Se in hyperaccumulators. Next, we summarize the fate of Se in plants, particularly hyperaccumulators. We then extensively review the impact of plant Se accumulation on ecological interactions. Finally, we discuss the potential impact of Se hyperaccumulators on local community composition and Se cycling. Selenium (hyper)accumulation offers ecological advantages: protection from herbivores and pathogens and competitive advantage over other plants. The extreme Se levels in and around hyperaccumulators create a toxic environment for Se-sensitive ecological partners, while offering a niche for Se-resistant partners. Through these dual effects, hyperaccumulators may influence species composition in their local environment, as well as Se cycling. The implied effects of Se hyperaccumulation on community assembly and local Se cycling warrant further investigations into the contribution of hyperaccumulators and general terrestrial vegetation to global Se cycling and may serve as a case study for how trace elements influence ecological processes. Furthermore, understanding ecological implications of plant Se accumulation are vital for safe implementation of biofortification and phytoremediation, technologies increasingly implemented to battle Se deficiency and toxicity. Copyright © 2018. Published by Elsevier B.V.

  11. Prevalence of Jews as subjects in genetic research: figures, explanation, and potential implications.

    Science.gov (United States)

    Carmeli, Daphna Birenbaum

    2004-09-15

    Geneticists' view of 'population isolates' as bearing special utility for research often translates into the targeting of such groups as study populations. This paper aims to outline the prevalence and structure of reference to one such group-that of the Jews-in genetic research publications. The paper uses three prevalence scores, calculated on the basis of a search of the PubMed database, conducted in September-October 2002. A systematic comparison to other population groups shows that in relation to the population size and in relation to the general bioscientific reference to this group, Jews are over-represented in human genetic literature, particularly in mutation-related contexts. This pattern is interpreted as representing geneticists' interest in Jewish communities, which are comparatively endogamous yet sizeable. It is also attributed to geneticists' access to Jewish communities, which is facilitated by the participation of Jewish scientists that alleviates ethical concerns as well. The geographical proximity of the largest Jewish communities to major research centers, and previous acquaintance with the genetic paradigm that many Jewish persons possess, further enhance this trend. The paper ends by pointing at potential extra-medical implications of this increased prevalence. Copyright 2004 Wiley-Liss, Inc.

  12. Mechanisms of radiation interaction with DNA: Potential implications for radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    1988-01-01

    The Office of Health and Environmental Research (OHER) of the US Department of Energy conducts a broad multidisciplinary research program which includes basic biophysics, biophysical chemistry, molecular and cellular biology as well as experimental animal studies and opportunistic human studies. This research is directed at understanding how low levels of radiation of various qualities produce the spectrum of biological effects that are seen for such exposures. This workshop was entitled ''Mechanisms of Radiation Interaction with DNA: Potential Implications for Radiation Protection.'' It ws jointly sponsored by the Department of Energy and the Commission of European Communities. The aim of the workshop was to review the base of knowledge in the area of mechanisms of radiation action at the DNA level, and to explore ways in which this information can be applied to the development of scientifically sound concepts and procedures for use in the field of radiation protection. The overview of research provided by this multidisciplinary group will be helpful to the Office in program planning. This report includes a summary of the presentations, extended abstracts, the meeting agenda, research recommendations, and a list of participants. Individual papers are processed separately for the data base.

  13. L-ferritin binding to scara5: a new iron traffic pathway potentially implicated in retinopathy.

    Directory of Open Access Journals (Sweden)

    Luísa Mendes-Jorge

    Full Text Available Iron is essential in the retina because the heme-containing enzyme guanylate cyclase modulates phototransduction in rods and cones. Transferrin endocytosis is the classical pathway for obtaining iron from the blood circulation in the retina. However, the iron storage protein ferritin has been also recently proposed as an iron carrier. In this study, the presence of Scara5 and its binding to L-ferritin was investigated in the retina. Our results showed that Scara5, the specific receptor for L-ferritin, was expressed in mouse and human retinas in many cell types, including endothelial cells. Furthermore, we showed that intravenously injected ferritin crossed the blood retinal barrier through L-ferritin binding to Scara5 in endothelial cells. Thus, suggesting the existence of a new pathway for iron delivery and trafficking in the retina. In a murine model of photoreceptor degeneration, Scara5 was downregulated, pointing out this receptor as a potential player implicated in retinopathy and also as a possible therapeutic target.

  14. Mechanisms of radiation interaction with DNA: Potential implications for radiation protection

    International Nuclear Information System (INIS)

    1988-01-01

    The Office of Health and Environmental Research (OHER) of the US Department of Energy conducts a broad multidisciplinary research program which includes basic biophysics, biophysical chemistry, molecular and cellular biology as well as experimental animal studies and opportunistic human studies. This research is directed at understanding how low levels of radiation of various qualities produce the spectrum of biological effects that are seen for such exposures. This workshop was entitled ''Mechanisms of Radiation Interaction with DNA: Potential Implications for Radiation Protection.'' It ws jointly sponsored by the Department of Energy and the Commission of European Communities. The aim of the workshop was to review the base of knowledge in the area of mechanisms of radiation action at the DNA level, and to explore ways in which this information can be applied to the development of scientifically sound concepts and procedures for use in the field of radiation protection. The overview of research provided by this multidisciplinary group will be helpful to the Office in program planning. This report includes a summary of the presentations, extended abstracts, the meeting agenda, research recommendations, and a list of participants. Individual papers are processed separately for the data base

  15. An integrated science-based methodology to assess potential risks and implications of engineered nanomaterials.

    Science.gov (United States)

    Tolaymat, Thabet; El Badawy, Amro; Sequeira, Reynold; Genaidy, Ash

    2015-11-15

    There is an urgent need for broad and integrated studies that address the risks of engineered nanomaterials (ENMs) along the different endpoints of the society, environment, and economy (SEE) complex adaptive system. This article presents an integrated science-based methodology to assess the potential risks of engineered nanomaterials. To achieve the study objective, two major tasks are accomplished, knowledge synthesis and algorithmic computational methodology. The knowledge synthesis task is designed to capture "what is known" and to outline the gaps in knowledge from ENMs risk perspective. The algorithmic computational methodology is geared toward the provision of decisions and an understanding of the risks of ENMs along different endpoints for the constituents of the SEE complex adaptive system. The approach presented herein allows for addressing the formidable task of assessing the implications and risks of exposure to ENMs, with the long term goal to build a decision-support system to guide key stakeholders in the SEE system towards building sustainable ENMs and nano-enabled products. Published by Elsevier B.V.

  16. Short report: secondary transmission in porcine cysticercosis: description and their potential implications for control sustainability.

    Science.gov (United States)

    Gonzalez, Armando E; López-Urbina, Teresa; Tsang, Byron Y; Gavidia, César M; Garcia, Héctor H; Silva, María E; Ramos, Daphne D; Manzanedo, Rafael; Sánchez-Hidalgo, Lelia; Gilman, Robert H; Tsang, Victor C W

    2005-09-01

    Taenia solium taeniasis/cysticercosis is one of few potentially eradicable infectious diseases and is the target of control programs in several countries. The larval stage of this zoonotic cestode invades the human brain and is responsible for most cases of adult-onset epilepsy in the world. The pig is the natural intermediate host, harboring the larvae or cysticerci. Our current understanding of the life cycle implicates humans as the only definitive host and tapeworm carrier (developing taeniasis) and thus the sole source of infective eggs that are responsible for cysticercosis in both human and pigs through oral-fecal transmission. Here we show evidence of an alternative pig-to-pig route of transmission, previously not suspected to exist. In a series of four experiments, naive sentinel pigs were exposed to pigs that had been infected orally with tapeworm segments (containing infective eggs) and moved to a clean environment. Consistently in all four experiments, at least one of the sentinel pigs became seropositive or infected with parasite cysts with much lower cyst burdens than did primarily infected animals. Second-hand transmission of Taenia solium eggs could explain the overdispersed pattern of porcine cysticercosis, with few pigs harboring heavy parasite burdens and many more harboring small numbers of parasites. This route of transmission opens new avenues for consideration with respect to control strategies.

  17. Cutaneous vasculitis in systemic lupus erythematosus patients: potential key players and implications.

    Science.gov (United States)

    Gheita, T A; Abaza, N M; Sayed, S; El-Azkalany, G S; Fishawy, H S; Eissa, A H

    2017-01-01

    Objectives The aim of the present work was to study the clinical characteristics of cutaneous vasculitis (CV) in systemic lupus erythematosus (SLE) patients and find possible potential key players in its development and implicated associations with the disease manifestations. Patients and methods Fifty adult female SLE patients underwent full history taking, thorough clinical examination and laboratory investigations. The SLE Disease Activity Index (SLEDAI) and accumulated damage using the Systemic Lupus International Collaborative Clinics/American College of Rheumatology Damage Index (SLICC/ACR DI) were assessed. Results The mean age of the patients was 29.1 ± 6.1 years and was significantly lower in those with CV ( p = 0.018). The disease duration was 4.9 ± 3.7 years. CV was present in 30% of the patients. Musculoskeletal manifestations and hypocomplementemia were present in all patients with CV. The SLEDAI and SLICC/ACR DI tended to be higher in those with CV. Complement (C3 and C4) was significantly consumed in CV patients ( p Lupus nephritis, cardiovascular manifestations and Sjögren syndrome were significantly linked to the development of CV ( p = 0.025, p = 0.023 and p lupus nephritis, musculoskeletal manifestations and Sjögren syndrome.

  18. Neuropathic Pain: Delving into the Oxidative Origin and the Possible Implication of Transient Receptor Potential Channels

    Directory of Open Access Journals (Sweden)

    Cristina Carrasco

    2018-02-01

    Full Text Available Currently, neuropathic pain is an underestimated socioeconomic health problem affecting millions of people worldwide, which incidence may increase in the next years due to chronification of several diseases, such as cancer and diabetes. Growing evidence links neuropathic pain present in several disorders [i.e., spinal cord injury (SCI, cancer, diabetes and alcoholism] to central sensitization, as a global result of mitochondrial dysfunction induced by oxidative and nitrosative stress. Additionally, inflammatory signals and the overload in intracellular calcium ion could be also implicated in this complex network that has not yet been elucidated. Recently, calcium channels namely transient receptor potential (TRP superfamily, including members of the subfamilies A (TRAP1, M (TRPM2 and 7, and V (TRPV1 and 4, have demonstrated to play a role in the nociception mediated by sensory neurons. Therefore, as neuropathic pain could be a consequence of the imbalance between reactive oxygen species and endogen antioxidants, antioxidant supplementation may be a treatment option. This kind of therapy would exert its beneficial action through antioxidant and immunoregulatory functions, optimizing mitochondrial function and even increasing the biogenesis of this vital organelle; on balance, antioxidant supplementation would improve the patient's quality of life. This review seeks to deepen on current knowledge about neuropathic pain, summarizing clinical conditions and probable causes, the relationship existing between oxidative stress, mitochondrial dysfunction and TRP channels activation, and scientific evidence related to antioxidant supplementation.

  19. Cadmium content of commercial and contaminated rice, Oryza sativa, in Thailand and potential health implications.

    Science.gov (United States)

    Zwicker, R; Promsawad, A; Zwicker, B M; Laoharojanaphand, S

    2010-03-01

    Thailand is the number one global exporter and among the top five producers of rice in the world. A significant increase in anthropogenic contamination in agricultural soils over the past few decades has lead to concerns with cadmium and its uptake in rice. The cadmium levels in Thai rice from different sources/areas were determined and used to estimate the potential health risks to consumers. The cadmium concentration in the commercial rice samples ranged from below the detection limit to 0.016 mg/kg. The cadmium concentrations in the contaminated rice samples ranged from a low of 0.007 mg/kg to a high of 0.579 mg/kg. Five of the calculated values exceed the proposed PTWI, with one value almost three times higher and two values almost double. The three highly elevated values are certainly a concern from a health standpoint. Ultimately, action is required to address the health implications resulting from the cadmium contamination in agricultural soils used for rice production in a few select areas of Thailand. Overall, this study indicates that the vast majority of rice produced, consumed and exported by Thailand is safe pertaining to cadmium content.

  20. Triglyceride blisters in lipid bilayers: implications for lipid droplet biogenesis and the mobile lipid signal in cancer cell membranes.

    Directory of Open Access Journals (Sweden)

    Himanshu Khandelia

    Full Text Available Triglycerides have a limited solubility, around 3%, in phosphatidylcholine lipid bilayers. Using millisecond-scale course grained molecular dynamics simulations, we show that the model lipid bilayer can accommodate a higher concentration of triolein (TO than earlier anticipated, by sequestering triolein molecules to the bilayer center in the form of a disordered, isotropic, mobile neutral lipid aggregate, at least 17 nm in diameter, which forms spontaneously, and remains stable on at least the microsecond time scale. The results give credence to the hotly debated existence of mobile neutral lipid aggregates of unknown function present in malignant cells, and to the early biogenesis of lipid droplets accommodated between the two leaflets of the endoplasmic reticulum membrane. The TO aggregates give the bilayer a blister-like appearance, and will hinder the formation of multi-lamellar phases in model, and possibly living membranes. The blisters will result in anomalous membrane probe partitioning, which should be accounted for in the interpretation of probe-related measurements.

  1. Selecting for creativity and innovation potential: implications for practice in healthcare education.

    Science.gov (United States)

    Patterson, Fiona; Zibarras, Lara Dawn

    2017-05-01

    The ability to innovate is an important requirement in many organisations. Despite this pressing need, few selection systems in healthcare focus on identifying the potential for creativity and innovation and so this area has been vastly under-researched. As a first step towards understanding how we might select for creativity and innovation, this paper explores the use of a trait-based measure of creativity and innovation potential, and evaluates its efficacy for use in selection for healthcare education. This study uses a sample of 188 postgraduate physicians applying for education and training in UK General Practice. Participants completed two questionnaires (a trait-based measure of creativity and innovation, and a measure of the Big Five personality dimensions) and were also rated by assessors on creative problem solving measured during a selection centre. In exploring the construct validity of the trait-based measure of creativity and innovation, our research clarifies the associations between personality, and creativity and innovation. In particular, our study highlights the importance of motivation in the creativity and innovation process. Results also suggest that Openness to Experience is positively related to creativity and innovation whereas some aspects of Conscientiousness are negatively associated with creativity and innovation. Results broadly support the utility of using a trait-based measure of creativity and innovation in healthcare selection processes, although practically this may be best delivered as part of an interview process, rather than as a screening tool. Findings are discussed in relation to broader implications for placing more priority on creativity and innovation as selection criteria within healthcare education and training in future.

  2. Evaluating spatial patterns of dioxins in sediments to aid determination of potential implications for marine reptiles

    Energy Technology Data Exchange (ETDEWEB)

    Hermanussen, S.; Gaus, C. [National Research Centre for Environmental Toxicology, Brisbane (Australia); Limpus, C.J. [Queensland Environmental Protection Agency, Brisbane (Australia); Paepke, O. [ERGO Forschungsgesellschaft mbH, Hamburg (Germany); Blanshard, W. [Sea World, Gold Coast (Australia); Connell, D. [School of Public Health, Griffith Univ., Brisbane (Australia)

    2004-09-15

    Recent investigations have identified elevated concentrations of polychlorinated dibenzo-p-dioxins (dioxins) in marine sediments and wildlife of Queensland, Australia. While it has been demonstrated that the contamination is widespread and predominantly land-based, limited information exists on the pathways and fate of these compounds within the near-shore marine system. This environment supports unique and threatened species including green sea turtles (Chelonia mydas). Adult green turtles are predominantly herbivorous, feeding on seagrass and algae. Apart from initial migration to feeding grounds (at {proportional_to}10 years of age) and intermittent migrations to breeding grounds (at {proportional_to}30-50 years and thereafter), green turtles remain and feed within relatively small home ranges. Long life-span (50 years or more), near-shore feeding grounds and highly specialized food requirements render green turtles potentially vulnerable to contaminant exposure. Recent studies have shown a relationship between PCDD/F concentrations found in herbivorous marine wildlife and concentrations in sediments of their habitats. Hence, the spatial evaluation of sediment PCDD/F distribution may assist the assessment of green turtle exposure and its potential implications. The present study provides baseline information on green turtle PCDD/F concentrations in Queensland, Australia and investigates exposure pathways. In addition, spatial distribution of PCDD/Fs in sediments from known green turtle feeding regions is assessed using geographic information systems. This represents the first stage of a large scale investigation into the exposure and sensitivity of marine reptiles to dioxins and dioxin-like compounds and to evaluate whether poor health status observed in some populations may be related to contaminant exposure.

  3. Plasma membranes modified by plasma treatment or deposition as solid electrolytes for potential application in solid alkaline fuel cells.

    Science.gov (United States)

    Reinholdt, Marc; Ilie, Alina; Roualdès, Stéphanie; Frugier, Jérémy; Schieda, Mauricio; Coutanceau, Christophe; Martemianov, Serguei; Flaud, Valérie; Beche, Eric; Durand, Jean

    2012-07-30

    In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane.

  4. Plasma Membranes Modified by Plasma Treatment or Deposition as Solid Electrolytes for Potential Application in Solid Alkaline Fuel Cells

    Science.gov (United States)

    Reinholdt, Marc; Ilie, Alina; Roualdès, Stéphanie; Frugier, Jérémy; Schieda, Mauricio; Coutanceau, Christophe; Martemianov, Serguei; Flaud, Valérie; Beche, Eric; Durand, Jean

    2012-01-01

    In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane. PMID:24958295

  5. 77 FR 44562 - Public Meeting: Potential Regulatory Implications of the Reduction of Lead in Drinking Water Act...

    Science.gov (United States)

    2012-07-30

    ... AGENCY 40 CFR Parts 141 and 142 Public Meeting: Potential Regulatory Implications of the Reduction of Lead in Drinking Water Act of 2011 AGENCY: Environmental Protection Agency (EPA). ACTION: Notice... discuss and solicit input from States, manufacturers, drinking water systems, other interested groups and...

  6. Phase separation of the plasma membrane in human red blood cells as a potential tool for diagnosis and progression monitoring of type 1 diabetes mellitus.

    Directory of Open Access Journals (Sweden)

    Giuseppe Maulucci

    Full Text Available Glycosylation, oxidation and other post-translational modifications of membrane and transmembrane proteins can alter lipid density, packing and interactions, and are considered an important factor that affects fluidity variation in membranes. Red blood cells (RBC membrane physical state, showing pronounced alterations in Type 1 diabetes mellitus (T1DM, could be the ideal candidate for monitoring the disease progression and the effects of therapies. On these grounds, the measurement of RBC membrane fluidity alterations can furnish a more sensitive index in T1DM diagnosis and disease progression than Glycosylated hemoglobin (HbA1c, which reflects only the information related to glycosylation processes. Here, through a functional two-photon microscopy approach we retrieved fluidity maps at submicrometric scale in RBC of T1DM patients with and without complications, detecting an altered membrane equilibrium. We found that a phase separation between fluid and rigid domains occurs, triggered by systemic effects on membranes fluidity of glycation and oxidation. The phase separation patterns are different among healthy, T1DM and T1DM with complications patients. Blood cholesterol and LDL content are positively correlated with the extent of the phase separation patterns. To quantify this extent a machine learning approach is employed to develop a Decision-Support-System (DSS able to recognize different fluidity patterns in RBC. Preliminary analysis shows significant differences(p<0.001 among healthy, T1DM and T1DM with complications patients. The development of an assay based on Phase separation of the plasma membrane of the Red Blood cells is a potential tool for diagnosis and progression monitoring of type 1 diabetes mellitus, and could allow customization and the selection of medical treatments in T1DM in clinical settings, and enable the early detection of complications.

  7. Evaluation of the membrane permeability (PAMPA and skin) of benzimidazoles with potential cannabinoid activity and their relation with the Biopharmaceutics Classification System (BCS).

    Science.gov (United States)

    Alvarez-Figueroa, M Javiera; Pessoa-Mahana, C David; Palavecino-González, M Elisa; Mella-Raipán, Jaime; Espinosa-Bustos, Cristián; Lagos-Muñoz, Manuel E

    2011-06-01

    The permeability of five benzimidazole derivates with potential cannabinoid activity was determined in two models of membranes, parallel artificial membrane permeability assay (PAMPA) and skin, in order to study the relationship of the physicochemical properties of the molecules and characteristics of the membranes with the permeability defined by the Biopharmaceutics Classification System. It was established that the PAMPA intestinal absorption method is a good predictor for classifying these molecules as very permeable, independent of their thermodynamic solubility, if and only if these have a Log P(oct) value <3.0. In contrast, transdermal permeability is conditioned on the solubility of the molecule so that it can only serve as a model for classifying the permeability of molecules that possess high solubility (class I: high solubility, high permeability; class III: high solubility, low permeability).

  8. Untapped potentials of acrylonitrile-butadiene-styrene/polyurethane (ABS/PU) blend membrane to purify dye wastewater.

    Science.gov (United States)

    Mandegari, Mansoor; Fashandi, Hossein

    2017-07-15

    Production of acrylonitrile-butadiene-styrene/polyurethane (ABS/PU) blend membrane with high rejection efficiency for disperse and vat dyes, is introduced as a facile and cost effective technique to purify textile wastewater. In this respect, membranes are produced using commercially available polymers, i.e. ABS and PU, with different compositions (ABS/PU: 100/0, 80/20, 70/30, 60/40 and 50/50 w/w) through wet casting. Casting solutions with concentration of 30 wt% are prepared using two different solvents, i.e. dimethylformamide (DMF) and N-methyl-2- pyrrolidone (NMP). The prepared membranes are characterized using a variety of analytical techniques including SEM imaging, FTIR spectroscopy, dry and wet gas permeation, evaluation of reusability, antifouling and mechanical properties, photostability, surface hydrophilicity and pure water permeability (PWP) of the produced membranes. According to the results, irrespective of solvent type, ABS/PU membranes with higher PU content have lower porosity and smaller pore size both of which contribute to enhanced dye rejection efficiency. This is while the impact of PU content on the photostability of ABS/PU membranes was found to be negligible. Additionally, the produced ABS/PU membranes exhibit good reusability and antifouling properties. However, the mechanical properties of ABS/PU membranes with higher PU contents are inferior to those with lower PU contents. This contrast highlights the prominence of optimum PU content to make a trade-off between dye rejection efficiency and mechanical properties. In this regard, ABS/PU (60/40 w/w) membrane is recognized as the one with optimum composition. Furthermore, it was found that regardless of PU content, membranes cast from DMF-based solutions exhibit superior rejection performance over those cast from NMP-based solutions. Overall, one can witness that employing ABS/PU membranes provides a meritorious and clean approach to refine disperse and vat dye wastewaters, a great threat

  9. Intrinsic mitochondrial membrane potential change and associated events mediate apoptosis in chemopreventive effect of diclofenac in colon cancer.

    Science.gov (United States)

    Kaur, Jasmeet; Sanyal, S N

    2010-01-01

    The present study explored the role of intrinsic mitochondrial membrane potential (delta psi M) in NSAID-induced apoptosis in the early stages of colon cancer. 1,2-Dimethylhydrazine dihydrochloride (DMH) was used to induce colon cancer and its chemoprevention was studied by diclofenac in a rat model. After 6 weeks of treatment with DMH (early stage), morphological analysis revealed a marked occurrence of preneoplastic features [i.e., mucosal plaque lesions (MPLs) in the colonic tissue]. Coadministration of diclofenac with DMH resulted in a significant reduction of these lesions, thereby proving the chemopreventive efficacy of diclofenac at the chosen anti-inflammatory dose. DMH treatment also led to a significant increase in delta psi M in the isolated colonocytes as assessed by JC-1 fluorescent staining, measured both by fluorescence microscopy and spectrofluorometerically. Further, there was seen a reduction in the number of cells showing low delta psi M, and hence monomer intensity of JC-1 by DMH treatment. To study the mechanism of these alterations in delta psi M in the present work, we studied the protein expression of important proapoptotic proteins, cytochrome c and Bax, by Western blot analysis and immunohistochemistry. DMH treatment reduced the mitochondrial translocation of Bax whereas cytochrome c was found to be located prominently in the mitochondria. Protein expression of antiapoptotic Bcl-2 was also studied in the colonic mucosa, which was expectedly found to be overexpressed after DMH treatment. Diclofenac treatment ameliorated the elevated delta psi M and its associated events to exert its chemopreventive action against early stages of colon cancer.

  10. Sperm DNA fragmentation and mitochondrial membrane potential combined are better for predicting natural conception than standard sperm parameters.

    Science.gov (United States)

    Malić Vončina, Slađana; Golob, Barbara; Ihan, Alojz; Kopitar, Andreja Nataša; Kolbezen, Mojca; Zorn, Branko

    2016-03-01

    To evaluate whether DNA fragmentation and/or mitochondrial membrane potential (MMP) predict natural conception better than standard sperm parameters. Prospective cross-sectional study. University medical center. Eighty-five infertile and 51 fertile men. Assessment of sperm DNA fragmentation, MMP, and standard semen parameters over a 6- to 12-month observation period. Comparison between the results of DNA fragmentation, MMP, and standard sperm parameters alone or combined and achievement of natural conception. Twenty-six of the 85 (31%) men from infertile couples conceived naturally. The median values of DNA fragmentation and MMP in the men who conceived within the observation period were similar to those in the fertile controls. Optimal threshold values of DNA fragmentation and MMP were 25% as determined by receiver operating characteristic analysis (area under the curve [AUC], 0.70; 95% confidence interval (CI) 0.58-0.82) and 62.5% (AUC, 0.68, 95% CI 0.56-0.80), respectively. The men in the infertile group with values of DNA fragmentation ≤25% and with MMP values ≥62.5% had significantly higher odds for conception (odds ratio [OR], 5.22; 95% CI 1.82-14.93] and OR, 4.67; 95% CI 1.74-12.5, respectively). Normal semen analysis alone had no predictive value for natural conception (OR, 1.84; 95% CI 0.67-5.07]). Both sperm function tests combined had significant odds for natural conception (OR, 8.24; 95% CI 2.91-23.33]), with a probability of 0.607 (60.7%) for both normal values and 0.158 (15.8%) for abnormal values. Sperm DNA fragmentation and MMP combined may be superior to standard semen parameters for the prediction of natural conception. Copyright © 2016. Published by Elsevier Inc.

  11. High-throughput BioSorter quantification of relative mitochondrial content and membrane potential in living Caenorhabditis elegans.

    Science.gov (United States)

    Kwon, Young Joon; Guha, Sujay; Tuluc, Florin; Falk, Marni J

    2018-05-01

    Mitochondrial respiratory chain disease is caused by a wide range of individually rare genetic disorders that impair cellular energy metabolism. While fluorescence microscopy analysis of nematodes fed MitoTracker Green (MTG) and tetramethylrhodamine ethyl ester (TMRE) can reliably quantify relative mitochondrial density and membrane potential, respectively, in C. elegans models of mitochondrial dysfunction, it is a tedious process with limitations in the number and age of animals that can be studied. A novel, large particle, flow cytometry-based method reported here accelerates and automates the relative quantitation of mitochondrial physiology in nematode populations. Relative fluorescence profiles of nematode populations co-labeled with MTG and TMRE were obtained and analyzed by BioSorter (Union Biometrica). Variables tested included genetic mutation (wild-type N2 Bristol versus nuclear-encoded respiratory chain complex I mutant gas-1(fc21) worms), animal age (day 1 versus day 4 adults), classical respiratory chain inhibitor and uncoupler effects (oligomycin, FCCP), and pharmacologic therapy duration (24h versus 96h treatments with glucose or nicotinic acid). A custom MATLAB script, which can be run on any computer with MATLAB runtime, was written to automatically quantify and analyze results in large animal populations. BioSorter analysis independently validated relative MTG and TMRE changes that we had previously performed by fluorescence microscopy in a variety of experimental conditions, with notably greater animal population sizes and substantially reduced experimental time. Older, fragile animal populations that are difficult to study by microscopy approaches were readily amenable to analysis with the BioSorter method. Overall, this high-throughput method enables efficient relative quantitation of in vivo mitochondrial physiology over time in a living animal in response to gene mutations and candidate therapies, which can be used to accelerate the

  12. Membrane potential and Ca2+ concentration dependence on pressure and vasoactive agents in arterial smooth muscle: A model.

    Science.gov (United States)

    Karlin, Arthur

    2015-07-01

    Arterial smooth muscle (SM) cells respond autonomously to changes in intravascular pressure, adjusting tension to maintain vessel diameter. The values of membrane potential (Vm) and sarcoplasmic Ca(2+) concentration (Ca(in)) within minutes of a change in pressure are the results of two opposing pathways, both of which use Ca(2+) as a signal. This works because the two Ca(2+)-signaling pathways are confined to distinct microdomains in which the Ca(2+) concentrations needed to activate key channels are transiently higher than Ca(in). A mathematical model of an isolated arterial SM cell is presented that incorporates the two types of microdomains. The first type consists of junctions between cisternae of the peripheral sarcoplasmic reticulum (SR), containing ryanodine receptors (RyRs), and the sarcolemma, containing voltage- and Ca(2+)-activated K(+) (BK) channels. These junctional microdomains promote hyperpolarization, reduced Ca(in), and relaxation. The second type is postulated to form around stretch-activated nonspecific cation channels and neighboring Ca(2+)-activated Cl(-) channels, and promotes the opposite (depolarization, increased Ca(in), and contraction). The model includes three additional compartments: the sarcoplasm, the central SR lumen, and the peripheral SR lumen. It incorporates 37 protein components. In addition to pressure, the model accommodates inputs of α- and β-adrenergic agonists, ATP, 11,12-epoxyeicosatrienoic acid, and nitric oxide (NO). The parameters of the equations were adjusted to obtain a close fit to reported Vm and Ca(in) as functions of pressure, which have been determined in cerebral arteries. The simulations were insensitive to ± 10% changes in most of the parameters. The model also simulated the effects of inhibiting RyR, BK, or voltage-activated Ca(2+) channels on Vm and Ca(in). Deletion of BK β1 subunits is known to increase arterial-SM tension. In the model, deletion of β1 raised Ca(in) at all pressures, and these

  13. Qualification of standard membrane-feeding assay with Plasmodium falciparum malaria and potential improvements for future assays.

    Directory of Open Access Journals (Sweden)

    Kazutoyo Miura

    Full Text Available Vaccines that interrupt malaria transmission are of increasing interest and a robust functional assay to measure this activity would promote their development by providing a biologically relevant means of evaluating potential vaccine candidates. Therefore, we aimed to qualify the standard membrane-feeding assay (SMFA. The assay measures the transmission-blocking activity of antibodies by feeding cultured P. falciparum gametocytes to Anopheles mosquitoes in the presence of the test antibodies and measuring subsequent mosquito infection. The International Conference on Harmonisation (ICH Harmonised Tripartite Guideline Q2(R1 details characteristics considered in assay validation. Of these characteristics, we decided to qualify the SMFA for Precision, Linearity, Range and Specificity. The transmission-blocking 4B7 monoclonal antibody was tested over 6 feeding experiments at several concentrations to determine four suitable concentrations that were tested in triplicate in the qualification experiments (3 additional feeds to evaluate Precision, Linearity and Range. For Specificity, 4B7 was tested in the presence of normal mouse IgG. We determined intra- and inter-assay variability of % inhibition of mean oocyst intensity at each concentration of 4B7 (lower concentrations showed higher variability. We also showed that % inhibition was dependent on 4B7 concentration and the activity is specific to 4B7. Since obtaining empirical data is time-consuming, we generated a model using data from all 9 feeds and simulated the effects of different parameters on final readouts to improve the assay procedure and analytical methods for future studies. For example, we estimated the effect of number of mosquitoes dissected on variability of % inhibition, and simulated the relationship between % inhibition in oocyst intensity and % inhibition of prevalence of infected mosquitos at different mean oocysts in the control. SMFA is one of the few biological assays used in

  14. Bioenergy costs and potentials with special attention to implications for the land system

    Science.gov (United States)

    Popp, A.; Lotze-Campen, H.; Dietrich, J.; Klein, D.; Bauer, N.; Krause, M.; Beringer, T.; Gerten, D.

    2011-12-01

    In the coming decades, an increasing competition for global land and water resources can be expected, due to rising demand for agricultural products, goals of nature conservation, and changing production conditions due to climate change. Especially biomass from cellulosic bioenergy crops, such as Miscanthus or poplar, is being proposed to play a substantial role in future energy systems if climate policy aims at stabilizing greenhouse gas (GHG) concentration at low levels. However, the potential of bioenergy for climate change mitigation remains unclear due to large uncertainties about future agricultural yield improvements, land availability for biomass plantations, and implications for the land system. In order to explore the cost-effective contribution of bioenergy to a low carbon transition with special attention to implications for the land system, we present a modeling framework with detailed biophysical and economic representation of the land and energy sector: We have linked the global dynamic vegetation and water balance model LPJmL (Bondeau et al. 2007, Rost et al. 2008), the global land and water use model MAgPIE (Lotze-Campen et al. 2008, Popp et al. 2010), and the global energy-economy-climate model ReMIND (Leimbach et al. 2009). In this modeling framework LPJmL supplies spatially explicit (0.5° resolution) agricultural yields as well as carbon and water stocks and fluxes. Based on this biophysical input MAgPIE delivers cost-optimized land use patterns (0.5° resolution), associated GHG emissions and rates of future yield increases in agricultural production. Moreover, shadow prices are calculated for irrigation water (as an indicator for water scarcity), food commodities, and bioenergy (as an indicator for changes in production costs) under different land use constraints such as forest conservation for climate change mitigation and as a contribution to biodiversity conservation. The energy-economy-climate model ReMIND generates the demand for

  15. Greater sage-grouse science (2015–17)—Synthesis and potential management implications

    Science.gov (United States)

    Hanser, Steven E.; Deibert, Patricia A.; Tull, John C.; Carr, Natasha B.; Aldridge, Cameron L.; Bargsten, Travis D.; Christiansen, Thomas J.; Coates, Peter S.; Crist, Michele R.; Doherty, Kevin E.; Ellsworth, Ethan A.; Foster, Lee J.; Herren, Vicki A.; Miller, Kevin H.; Moser, Ann; Naeve, Robin M.; Prentice, Karen L.; Remington, Thomas E.; Ricca, Mark A.; Shinneman, Douglas J.; Truex, Richard L.; Wiechman , Lief A.; Wilson, Dereck C.; Bowen, Zachary H.

    2018-02-15

    Strategy Actionable Science Plan Team, 2016).In October 2017, after a review of the 2015 Federal plans relative to State sage-grouse plans, in accordance with Secretarial Order 3353, the BLM issued a notice of intent to consider whether to amend some, all, or none of the 2015 land use plans. At that time, the BLM requested the U.S. Geological Survey (USGS) to inform this effort through the development of an annotated bibliography of sage-grouse science published since January 2015 and a report that synthesized and outlined the potential management implications of this new science. Development of the annotated bibliography resulted in the identification and summarization of 169 peer-reviewed scientific publications and reports. The USGS then convened an interagency team (hereafter referred to as the “team”) to develop this report that focuses on the primary topics of importance to the ongoing management of sage-grouse and their habitats.The team developed this report in a three-step process. First, the team identified six primary topic areas for discussion based on the members’ collective knowledge regarding sage-grouse, their habitats, and threats to either or both. Second, the team reviewed all the material in the “Annotated Bibliography of Scientific Research on Greater Sage-Grouse Published since January 2015” to identify the science that addressed the topics. Third, team members discussed the science related to each topic, evaluated the consistency of the science with existing knowledge before 2015, and summarized the potential management implications of this science. The six primary topics identified by the team were:Multiscale habitat suitability and mapping toolsDiscrete anthropogenic activitiesDiffuse activitiesFire and invasive speciesRestoration effectivenessPopulation estimation and genetics

  16. Evaluation of the regenerative potential of 25% doxycycline-loaded biodegradable membrane vs biodegradable membrane alone in the treatment of human periodontal infrabony defects: A clinical and radiological study

    Directory of Open Access Journals (Sweden)

    Chaturvedi Rashi

    2008-01-01

    Full Text Available Background: Microbial colonization of the barrier membranes used for guided tissue regeneration is inevitable and can lead to delayed healing. Aims: Antimicrobial coating of the membrane with 25% doxycycline paste has been attempted to prevent infection and achieve enhanced regeneration in periodontal infrabony defects. Materials and Methods: Twenty-four patients with 2-walled or 3-walled infrabony defects were selected and randomly divided into two equal groups. Infrabony defects of group A were treated with a biodegradable membrane coated with 25% doxycycline while those of group B were treated with membrane alone. Clinical assessment of probing depth and attachment level and radiographic evaluation of the defect depth was done preoperatively and at 12 and 24 weeks postoperatively. Statistical Analysis: The relative efficacy of the two treatment modalities were evaluated using the paired Student′s t- test and the comparative evaluation between the two groups was done using the independent Student′s t -test. Results: Both the groups exhibited a highly significant reduction in probing depth and gain in clinical attachment level and linear bone fill at the end of 24 weeks. Comparative evaluation between the two study groups revealed a significant reduction in probing depth ( P = 0.016 FNx01 and linear bone fill ( P = 0.02 FNx01 in group A as compared to group B. Mean gain in attachment level was greater for group A than for group B but the difference was statistically nonsignificant ( P = 0.065 NS . Conclusions: The results suggest that doxycycline is beneficial in reducing membrane-associated infection and can potentiate regeneration through host modulation.

  17. Hemi-bucket-handle tears of the meniscus: appearance on MRI and potential surgical implications

    International Nuclear Information System (INIS)

    Engstrom, Bjorn I.; Vinson, Emily N.; Helms, Clyde A.; Taylor, Dean C.; Garrett, William E.

    2012-01-01

    To describe a type of meniscus flap tear resembling a bucket-handle tear, named a ''hemi-bucket-handle'' tear; to compare its imaging features with those of a typical bucket-handle tear; and to discuss the potential therapeutic implications of distinguishing these two types of tears. Five knee MR examinations were encountered with a type of meniscus tear consisting of a flap of tissue from the undersurface of the meniscus displaced toward the intercondylar notch. A retrospective analysis of 100 MR examinations prospectively interpreted as having bucket-handle type tears yielded 10 additional cases with this type of tear. Cases of hemi-bucket-handle tears were reviewed for tear location and orientation, appearance of the superior articular surface of the meniscus, presence and location of displaced meniscal tissue, and presence of several classic signs of bucket-handle tears. A total of 15/15 tears involved the medial meniscus, had tissue displaced toward the notch, and were mainly horizontal in orientation. The superior surface was intact in 11/15 (73.3%). In 1/15 (6.7%) there was an absent-bow-tie sign; 6/15 (40%) had a double-PCL sign; 14/15 (93.3%) had a double-anterior horn sign. We describe a type of undersurface flap tear, named a hemi-bucket-handle tear, which resembles a bucket-handle tear. Surgeons at our institution feel this tear would likely not heal if repaired given its predominantly horizontal orientation, and additionally speculate the tear could be overlooked at arthroscopy. Thus, we feel it is important to distinguish this type of tear from the typical bucket-handle tear. (orig.)

  18. Structures of the signal recognition particle receptor from the archaeon Pyrococcus furiosus: implications for the targeting step at the membrane.

    Science.gov (United States)

    Egea, Pascal F; Tsuruta, Hiro; de Leon, Gladys P; Napetschnig, Johanna; Walter, Peter; Stroud, Robert M

    2008-01-01

    In all organisms, a ribonucleoprotein called the signal recognition particle (SRP) and its receptor (SR) target nascent proteins from the ribosome to the translocon for secretion or membrane insertion. We present the first X-ray structures of an archeal FtsY, the receptor from the hyper-thermophile Pyrococcus furiosus (Pfu), in its free and GDP*magnesium-bound forms. The highly charged N-terminal domain of Pfu-FtsY is distinguished by a long N-terminal helix. The basic charges on the surface of this helix are likely to regulate interactions at the membrane. A peripheral GDP bound near a regulatory motif could indicate a site of interaction between the receptor and ribosomal or SRP RNAs. Small angle X-ray scattering and analytical ultracentrifugation indicate that the crystal structure of Pfu-FtsY correlates well with the average conformation in solution. Based on previous structures of two sub-complexes, we propose a model of the core of archeal and eukaryotic SRP*SR targeting complexes.

  19. Structures of the Signal Recognition Particle Receptor From the Archaeon Pyrococcus Furiosus: Implications for the Targeting Step at the Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Egea, P.F.; Tsuruta, H.; Leon, G.P.de; Napetschnig, J.; Walter, P.; Stroud, R.M.

    2009-05-18

    In all organisms, a ribonucleoprotein called the signal recognition particle (SRP) and its receptor (SR) target nascent proteins from the ribosome to the translocon for secretion or membrane insertion. We present the first X-ray structures of an archeal FtsY, the receptor from the hyper-thermophile Pyrococcus furiosus (Pfu), in its free and GDP {center_dot} magnesium-bound forms. The highly charged N-terminal domain of Pfu-FtsY is distinguished by a long N-terminal helix. The basic charges on the surface of this helix are likely to regulate interactions at the membrane. A peripheral GDP bound near a regulatory motif could indicate a site of interaction between the receptor and ribosomal or SRP RNAs. Small angle X-ray scattering and analytical ultracentrifugation indicate that the crystal structure of Pfu-FtsY correlates well with the average conformation in solution. Based on previous structures of two sub-complexes, we propose a model of the core of archeal and eukaryotic SRP {center_dot} SR targeting complexes.

  20. Recycling of glucagon receptor to plasma membrane increases in adipocytes of obese rats by soy protein; implications for glucagon resistance.

    Science.gov (United States)

    Velázquez-Villegas, Laura A; Tovar-Palacio, Claudia; Palacios-González, Berenice; Torres, Nimbe; Tovar, Armando R; Díaz-Villaseñor, Andrea

    2017-10-01

    Hyperglucagonemia contributes to hyperglycemia in type 2 diabetes (T2D). Previously, we have found that soy protein normalized fasting hyperglucagonemia in obese Zucker (fa/fa) rats, sensitizing the HSL-lipolytic signaling pathway in white adipose tissue (WAT), however the mechanism remains unknown. Zucker (fa/fa) rats were fed casein or soy protein diet in combination with soybean or coconut oil. Glucagon receptor (GR) was increased at the plasma membrane of adipocytes of rats fed soy protein compared to those fed casein, without changes in total GR abundance. The protein abundance of Rab4, a GTPase involved in GR fast recycling, was dramatically up-regulated in adipocytes of rats fed soy protein. The proportion of GR bound to Rab4 or to RAMP2, involved in promoting GR ligand-binding and G protein selectivity, increased when soy protein was combined with soybean oil as fat source. In rats fed soy protein with coconut oil, Rab11 levels, a protein involved in the slow recycling of GR, was also increased. Soy protein increases GR recycling to the membrane of adipocytes and its ligand-binding and G protein selectivity, suggesting, it could be used in T2D dietary treatment to reestablish glucagon sensitivity in WAT, leading to the regulation of circulating glucagon levels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Biofouling potential reductions using a membrane hybrid system as a pre-treatment to seawater reverse osmosis.

    Science.gov (United States)

    Jeong, Sanghyun; Kim, Lan Hee; Kim, Sung-Jo; Nguyen, Tien Vinh; Vigneswaran, Saravanamuthu; Kim, In S

    2012-07-01

    Biofouling on reverse osmosis (RO) membranes is the most serious problem which affects desalination process efficiency and increases operation cost. The biofouling cannot be effectively removed by the conventional pre-treatment traditionally used in desalination plants. Hybrid membrane systems coupling the adsorption and/or coagulation with low-pressure membranes can be a sustainable pre-treatment in reducing membrane fouling and at the same time improving the feed water quality to the seawater reverse osmosis. The addition of powder activated carbon (PAC) of 1.5 g/L into submerged membrane system could help to remove significant amount of both hydrophobic compounds (81.4%) and hydrophilic compounds (73.3%). When this submerged membrane adsorption hybrid system (SMAHS) was combined with FeCl(3) coagulation of 0.5 mg of Fe(3+)/L, dissolved organic carbon removal efficiency was excellent even with lower dose of PAC (0.5 g/L). Detailed microbial studies conducted with the SMAHS and the submerged membrane coagulation-adsorption hybrid system (SMCAHS) showed that these hybrid systems can significantly remove the total bacteria which contain also live cells. As a result, microbial adenosine triphosphate (ATP) as well as total ATP concentrations in treated seawater and foulants was considerably decreased. The bacteria number in feed water prior to RO reduced from 5.10E(+06) cells/mL to 3.10E(+03) cells/mL and 9.30E(+03) cells/mL after SMAHS and SMCAHS were applied as pre-treatment, respectively. These led to a significant reduction of assimilable organic carbon (AOC) by 10.1 μg/L acetate-C when SMCAHS was used as a pre-treatment after 45-h RO operation. In this study, AOC method was modified to measure the growth of bacteria in seawater by using the Pseudomonas P.60 strain.

  2. Laminar shear stress regulates endothelial kinin B1 receptor expression and function: potential implication in atherogenesis

    Science.gov (United States)

    Duchene, Johan; Cayla, Cécile; Vessillier, Sandrine; Scotland, Ramona; Yamashiro, Kazuo; Lecomte, Florence; Syed, Irfan; Vo, Phuong; Marrelli, Alessandra; Pitzalis, Costantino; Cipollone, Francesco; Schanstra, Joost; Bascands, Jean-Loup; Hobbs, Adrian J; Perretti, Mauro; Ahluwalia, Amrita

    2009-01-01

    OBJECTIVE The pro-inflammatory phenotype induced by low laminar shear stress (LSS) is implicated in atherogenesis. The kinin B1 receptor (B1R), known to be induced by inflammatory stimuli, exerts many pro-inflammatory effects including vasodilatation and leukocyte recruitment. We investigated whether low LSS is a stimulus for endothelial B1R expression and function. METHODS AND RESULTS Human and mouse atherosclerotic plaques expressed high level of B1R mRNA and protein. In addition, B1R expression was upregulated in the aortic arch (low LSS region) of ApoE-/- mice fed a high fat diet compared to vascular regions of high LSS and animals fed normal chow. Of interest, a greater expression of B1R was noticed in endothelial cells from regions of low LSS in aortic arch of ApoE-/- mice. B1R was also upregulated in human umbilical vein endothelial cells (HUVEC) exposed to low LSS (0-2dyn/cm2) compared to physiological LSS (6-10dyn/cm2): an effect similarly evident in murine vascular tissue perfused ex vivo. Functionally, B1R activation increased prostaglandin and CXCL5 expression in cells exposed to low, but not physiological, LSS. IL-1β and ox-LDL induced B1R expression and function in HUVECs, a response substantially enhanced under low LSS conditions and inhibited by blockade of NFκB activation. CONCLUSION Herein, we show that LSS is a major determinant of functional B1R expression in endothelium. Furthermore, whilst physiological high LSS is a powerful repressor of this inflammatory receptor, low LSS at sites of atheroma are associated with substantial upregulation, identifying this receptor as a potential therapeutic target. CONDENSED ABSTRACT Low laminar shear stress (LSS) underlies the pro-inflammatory processes in atherogenesis. Herein, we demonstrate that whilst physiological LSS represses inflammatory kinin B1 receptor (B1R) expression/function, low atherogenic LSS is associated with profound upregulation of both in atherosclerosis in both humans and animal

  3. Tolerance, bioavailability, and potential cognitive health implications of a distinct aqueous spearmint extract

    Directory of Open Access Journals (Sweden)

    Kristin M. Nieman

    2015-05-01

    Full Text Available Background: Cognitive function can decline during the aging process and significantly reduce quality of life. Although a number of interventions have been investigated for cognitive dysfunction, including antioxidants, this prominent health concern emphasizes a need to explore methods to support cognitive health later in the life span. An aqueous extract from a proprietary spearmint line has been developed which contains a number of antioxidant compounds, including rosmarinic acid, at levels that are higher than found in commercially-bred spearmint. Therefore, this pilot trial assessed the tolerance, bioavailability, and potential cognitive health implications of a proprietary spearmint extract in men and women with self-reported memory impairment. Methods: Subjects consumed 900 mg/day spearmint extract for 30 days. The sample population (N = 11 was 73% female and 27% male with a mean age of 58.7 ± 1.6 y. Tolerability parameters were assessed at baseline and end of treatment visits. Computerized cognitive function tests were completed and blood was drawn at pre- and post-dose (0.5 to 4 h timepoints during baseline and end of treatment visits. Subjective cognition was also assessed at end of treatment. Results: No serious adverse events or clinically relevant findings were observed in any tolerability parameters. Plasma vanillic, caffeic, and ferulic acid sulfates, rosmarinic acid, and methyl rosmarinic acid glucuronide were detected in plasma following acute administration of the spearmint extract. Computerized cognitive function scores improved in reasoning (P =0.023 and attention/concentration (P = 0.002 after 30 days of supplementation. After acute administration, subjects had improved attention/concentration in two tests at 2 (P = 0.042 and P = 0.025 and 4 h (P = 0.001 and P = 0.002. Conclusions: The results from this pilot trial suggest that the spearmint extract, which contains higher rosmarinic acid content relative to extracts from

  4. Phase separation of the plasma membrane in human red blood cells as a potential tool for diagnosis and progression monitoring of type 1 diabetes mellitus.

    Science.gov (United States)

    Maulucci, Giuseppe; Cordelli, Ermanno; Rizzi, Alessandro; De Leva, Francesca; Papi, Massimiliano; Ciasca, Gabriele; Samengo, Daniela; Pani, Giovambattista; Pitocco, Dario; Soda, Paolo; Ghirlanda, Giovanni; Iannello, Giulio; De Spirito, Marco

    2017-01-01

    Glycosylation, oxidation and other post-translational modifications of membrane and transmembrane proteins can alter lipid density, packing and interactions, and are considered an important factor that affects fluidity variation in membranes. Red blood cells (RBC) membrane physical state, showing pronounced alterations in Type 1 diabetes mellitus (T1DM), could be the ideal candidate for monitoring the disease progression and the effects of therapies. On these grounds, the measurement of RBC membrane fluidity alterations can furnish a more sensitive index in T1DM diagnosis and disease progression than Glycosylated hemoglobin (HbA1c), which reflects only the information related to glycosylation processes. Here, through a functional two-photon microscopy approach we retrieved fluidity maps at submicrometric scale in RBC of T1DM patients with and without complications, detecting an altered membrane equilibrium. We found that a phase separation between fluid and rigid domains occurs, triggered by systemic effects on membranes fluidity of glycation and oxidation. The phase separation patterns are different among healthy, T1DM and T1DM with complications patients. Blood cholesterol and LDL content are positively correlated with the extent of the phase separation patterns. To quantify this extent a machine learning approach is employed to develop a Decision-Support-System (DSS) able to recognize different fluidity patterns in RBC. Preliminary analysis shows significant differences(pBlood cells is a potential tool for diagnosis and progression monitoring of type 1 diabetes mellitus, and could allow customization and the selection of medical treatments in T1DM in clinical settings, and enable the early detection of complications.

  5. Triglyceride Blisters in Lipid Bilayers: Implications for Lipid Droplet Biogenesis and the Mobile Lipid Signal in Cancer Cell Membranes

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Duelund, Lars; Pakkanen, Kirsi Inkeri

    2010-01-01

    aggregates of unknown function present in malignant cells, and to the early biogenesis of lipid droplets accommodated between the two leaflets of the endoplasmic reticulum membrane. The TO aggregates give the bilayer a blister-like appearance, and will hinder the formation of multi-lamellar phases in model......Triglycerides have a limited solubility, around 3%, in phosphatidylcholine lipid bilayers. Using millisecond-scale course grained molecular dynamics simulations, we show that the model lipid bilayer can accommodate a higher concentration of triolein (TO) than earlier anticipated, by sequestering...... triolein molecules to the bilayer center in the form of a disordered, isotropic, mobile neutral lipid aggregate, at least 17 nm in diameter, which forms spontaneously, and remains stable on at least the microsecond time scale. The results give credence to the hotly debated existence of mobile neutral lipid...

  6. Potential of Pervaporation and Vapor Separation with Water Selective Membranes for an Optimized Production of Biofuels—A Review

    Directory of Open Access Journals (Sweden)

    Catia Cannilla

    2017-06-01

    Full Text Available The development of processes based on the integration of new technologies is of growing interest to industrial catalysis. Recently, significant efforts have been focused on the design of catalytic membrane reactors to improve process performance. In particular, the use of membranes, that allow a selective permeation of water from the reaction mixture, positively affects the reaction evolution by improving conversion for all reactions thermodynamically or kinetically limited by the presence of water. In this paper, how pervaporation (PV and vapor permeation (VP technologies can improve the catalytic performance of reactions of industrial interest is considered. Specifically, technological approaches proposed in the literature are discussed with the aim of highlighting advantages and problems encountered in order to address research towards the optimization of membrane reactor configurations for liquid biofuel production in large scale.

  7. Antimicrobial properties and membrane-active mechanism of a potential α-helical antimicrobial derived from cathelicidin PMAP-36.

    Directory of Open Access Journals (Sweden)

    Yinfeng Lv

    Full Text Available Antimicrobial peptides (AMPs, which present in the non-specific immune system of organism, are amongst the most promising candidates for the development of novel antimicrobials. The modification of naturally occurring AMPs based on their residue composition and distribution is a simple and effective strategy for optimization of known AMPs. In this study, a series of truncated and residue-substituted derivatives of antimicrobial peptide PMAP-36 were designed and synthesized. The 24-residue truncated peptide, GI24, displayed antimicrobial activity comparable to the mother peptide PMAP-36 with MICs ranging from 1 to 4 µM, which is lower than the MICs of bee venom melittin. Although GI24 displayed high antimicrobial activity, its hemolytic activity was much lower than melittin, suggesting that GI24 have optimal cell selectivity. In addition, the crucial site of GI24 was identified through single site-mutation. An amino acid with high hydrophobicity at position 23 played an important role in guaranteeing the high antimicrobial activity of GI24. Then, lipid vesicles and whole bacteria were employed to investigate the membrane-active mechanisms. Membrane-simulating experiments showed that GI24 interacted strongly with negatively charged phospholipids and weakly with zwitterionic phospholipids, which corresponded well with the data of its biological activities. Membrane permeabilization and flow cytometry provide the evidence that GI24 killed microbial cells by permeabilizing the cell membrane and damaging membrane integrity. GI24 resulted in greater cell morphological changes and visible pores on cell membrane as determined using scanning electron microscopy (SEM and transmission electron microscope (TEM. Taken together, the peptide GI24 may provide a promising antimicrobial agent for therapeutic applications against the frequently-encountered bacteria.

  8. A common pathway for regulation of nutritive blood flow to the brain: arterial muscle membrane potential and cytochrome P450 metabolites.

    Science.gov (United States)

    Harder, D R; Roman, R J; Gebremedhin, D; Birks, E K; Lange, A R

    1998-12-01

    Perfusion pressure to the brain must remain relatively constant to provide rapid and efficient distribution of blood to metabolically active neurones. Both of these processes are regulated by the level of activation and tone of cerebral arterioles. The active state of cerebral arterial muscle is regulated, to a large extent, by the level of membrane potential. At physiological levels of arterial pressure, cerebral arterial muscle is maintained in an active state owing to membrane depolarization, compared with zero pressure load. As arterial pressure changes, so does membrane potential. The membrane is maintained in a relatively depolarized state because of, in part, inhibition of K+ channel activity. The activity of K+ channels, especially the large conductance Ca(2+)-activated K+ channel (KCa) is dependent upon the level of 20-HETE produced by arterial muscle. As arterial pressure increases, so does cytochrome P450 (P4504A) activity. P4504A enzymes catalyse omega-hydroxylation of arachidonic acid and formation of 20-hydroxyeicosatetraenoic acid (20-HETE). 20-HETE is a potent inhibitor of KCa which maintains membrane depolarization and muscle cell activation. Astrocytes also metabolize AA via P450 enzymes of the 2C11 gene family to produce epoxyeicosatrienoic acids (EETs). Epoxyeicosatrienoic acids are released from astrocytes by glutamate which 'spills over' during neuronal activity. These locally released EETs shunt blood to metabolically active neurones providing substrate to support neuronal function. This short paper will discuss the findings which support the above scenario, the purpose of which is to provide a basis for future studies on the molecular mechanisms through which cerebral blood flow matches metabolism.

  9. PathogenicLeptospiraSecreted Proteases Target the Membrane Attack Complex: A Potential Role for Thermolysin in Complement Inhibition.

    Science.gov (United States)

    Amamura, Thais A; Fraga, Tatiana R; Vasconcellos, Sílvio A; Barbosa, Angela S; Isaac, Lourdes

    2017-01-01

    Leptospirosis is a zoonosis caused by spirochetes from the genus Leptospira . This disease is common in tropical and subtropical areas, constituting a serious public health problem. Pathogenic Leptospira have the ability to escape the human Complement System, being able to survive when in contact with normal human serum. In a previous study, our group demonstrated that supernatants of pathogenic Leptospira (SPL) inhibit the three activation pathways of the Complement System. This inhibition can be directly correlated with the activity of secreted proteases, which cleave the Complement molecules C3, Factor B (Alternative Pathway), C4 and C2 (Classical and Lectin Pathways). In this work, we analyze the activity of the leptospiral proteases on the components of Terminal Pathway of Complement, called the membrane attack complex (MAC). We observed that proteases present in SPL from different Leptospira strains were able to cleave the purified proteins C5, C6, C7, C8, and C9, while culture supernatant from non-pathogenic Leptospira strains (SNPL) had no significant proteolytic activity on these substrates. The cleavages occurred in a time-dependent and specificity manner. No cleavage was observed when we used whole serum as a source of C5-C9 proteins, probably because of the abundant presence of plasma protease inhibitors such as α 2 -macroglobulin. Complement protein cleavage by SPL was inhibited by 1,10-phenanthroline, indicating the involvement of metalloproteases. Furthermore, 1,10-phenanthroline- treated normal human serum diminished pathogenic leptospira survival. We also analyzed the proteolytic activity of thermolysin (LIC13322) a metalloprotease expressed exclusively by pathogenic Leptospira strains. Recombinant thermolysin was capable of cleaving the component C6, either purified or as part of the SC5b-9 complex. Furthermore, we found that the MAC proteins C6-C9 interact with thermolysin, indicating that this metalloprotease may have an additional inhibitory

  10. Pathogenic Leptospira Secreted Proteases Target the Membrane Attack Complex: A Potential Role for Thermolysin in Complement Inhibition

    Directory of Open Access Journals (Sweden)

    Thais A. Amamura

    2017-05-01

    Full Text Available Leptospirosis is a zoonosis caused by spirochetes from the genus Leptospira. This disease is common in tropical and subtropical areas, constituting a serious public health problem. Pathogenic Leptospira have the ability to escape the human Complement System, being able to survive when in contact with normal human serum. In a previous study, our group demonstrated that supernatants of pathogenic Leptospira (SPL inhibit the three activation pathways of the Complement System. This inhibition can be directly correlated with the activity of secreted proteases, which cleave the Complement molecules C3, Factor B (Alternative Pathway, C4 and C2 (Classical and Lectin Pathways. In this work, we analyze the activity of the leptospiral proteases on the components of Terminal Pathway of Complement, called the membrane attack complex (MAC. We observed that proteases present in SPL from different Leptospira strains were able to cleave the purified proteins C5, C6, C7, C8, and C9, while culture supernatant from non-pathogenic Leptospira strains (SNPL had no significant proteolytic activity on these substrates. The cleavages occurred in a time-dependent and specificity manner. No cleavage was observed when we used whole serum as a source of C5–C9 proteins, probably because of the abundant presence of plasma protease inhibitors such as α2-macroglobulin. Complement protein cleavage by SPL was inhibited by 1,10-phenanthroline, indicating the involvement of metalloproteases. Furthermore, 1,10-phenanthroline- treated normal human serum diminished pathogenic leptospira survival. We also analyzed the proteolytic activity of thermolysin (LIC13322 a metalloprotease expressed exclusively by pathogenic Leptospira strains. Recombinant thermolysin was capable of cleaving the component C6, either purified or as part of the SC5b-9 complex. Furthermore, we found that the MAC proteins C6–C9 interact with thermolysin, indicating that this metalloprotease may have an

  11. Pathogenic Leptospira Secreted Proteases Target the Membrane Attack Complex: A Potential Role for Thermolysin in Complement Inhibition

    Science.gov (United States)

    Amamura, Thais A.; Fraga, Tatiana R.; Vasconcellos, Sílvio A.; Barbosa, Angela S.; Isaac, Lourdes

    2017-01-01

    Leptospirosis is a zoonosis caused by spirochetes from the genus Leptospira. This disease is common in tropical and subtropical areas, constituting a serious public health problem. Pathogenic Leptospira have the ability to escape the human Complement System, being able to survive when in contact with normal human serum. In a previous study, our group demonstrated that supernatants of pathogenic Leptospira (SPL) inhibit the three activation pathways of the Complement System. This inhibition can be directly correlated with the activity of secreted proteases, which cleave the Complement molecules C3, Factor B (Alternative Pathway), C4 and C2 (Classical and Lectin Pathways). In this work, we analyze the activity of the leptospiral proteases on the components of Terminal Pathway of Complement, called the membrane attack complex (MAC). We observed that proteases present in SPL from different Leptospira strains were able to cleave the purified proteins C5, C6, C7, C8, and C9, while culture supernatant from non-pathogenic Leptospira strains (SNPL) had no significant proteolytic activity on these substrates. The cleavages occurred in a time-dependent and specificity manner. No cleavage was observed when we used whole serum as a source of C5–C9 proteins, probably because of the abundant presence of plasma protease inhibitors such as α2-macroglobulin. Complement protein cleavage by SPL was inhibited by 1,10-phenanthroline, indicating the involvement of metalloproteases. Furthermore, 1,10-phenanthroline- treated normal human serum diminished pathogenic leptospira survival. We also analyzed the proteolytic activity of thermolysin (LIC13322) a metalloprotease expressed exclusively by pathogenic Leptospira strains. Recombinant thermolysin was capable of cleaving the component C6, either purified or as part of the SC5b-9 complex. Furthermore, we found that the MAC proteins C6–C9 interact with thermolysin, indicating that this metalloprotease may have an additional inhibitory

  12. HBCDD-induced sustained reduction in mitochondrial membrane potential, ATP and steroidogenesis in peripubertal rat Leydig cells

    Energy Technology Data Exchange (ETDEWEB)

    Fa, Svetlana; Pogrmic-Majkic, Kristina; Samardzija, Dragana; Hrubik, Jelena; Glisic, Branka; Kovacevic, Radmila; Andric, Nebojsa, E-mail: nebojsa.andric@dbe.uns.ac.rs

    2015-01-01

    Hexabromocyclododecane (HBCDD), a brominated flame retardant added to various consumer products, is a ubiquitous environmental contaminant. We have previously shown that 6-hour exposure to HBCDD disturbs basal and human chorionic gonadotropin (hCG)-induced steroidogenesis in rat Leydig cells. Reduction in mitochondrial membrane potential (ΔΨm) and cAMP production was also observed. Here, we further expanded research on the effect of HBCDD on Leydig cells by using a prolonged exposure scenario. Cells were incubated in the presence of HBCDD during 24 h and then treated with HBCDD + hCG for additional 2 h. Results showed that HBCDD caused a sustained reduction in ATP level after 24 h of exposure, which persisted after additional 2-hour treatment with HBCDD + hCG. cAMP and androgen accumulations measured after 2 h of HBCDD + hCG treatment were also inhibited. Real-time PCR analysis showed significant inhibition in the expression of genes for steroidogenic enzymes, luteinizing hormone receptor, regulatory and transport proteins, and several transcription factors under both treatment conditions. Western blot analysis revealed a decreased level of 30 kDa steroidogenic acute regulatory protein (StAR) after HBCDD + hCG treatment. In addition, HBCDD decreased the conversion of 22-OH cholesterol to pregnenolone and androstenedione to testosterone, indicating loss of the activity of cytochrome P450C11A1 (CYP11A1) and 17β-hydroxysteroid dehydrogenase (HSD17β). Cell survival was not affected, as confirmed by cytotoxicity and trypan blue tests or DNA fragmentation analysis. In summary, our data showed that HBCDD inhibits ATP supply, most likely through a decrease in ΔΨm, and targets multiple sites in the steroidogenic pathway in Leydig cells. - Highlights: • HBCDD causes a sustained reduction in ΔΨm and ATP level in Leydig cells. • Prolonged HBCDD exposure decreases hCG-supported steroidogenesis in Leydig cells. • HBCDD targets StAR, HSD17β and CYP11A1 in Leydig

  13. [Study on apoptosis, cytochrome C and mitochondrial membrane potential in CD71(+) nucleated erythrocytes in patients with chronic mountain sickness].

    Science.gov (United States)

    Wang, S Y; Cui, S; Li, Z Q; Ji, L H; Ma, J; Liu, H H; Zhang, G Y; Suo, S H; Ge, R L

    2018-02-13

    Objective: To investigate the changes of CD71(+) nucleated erythrocyte apoptosis, cytochrome C (Cyt-C) and mitochondrial membrane potential (MMP) in bone marrow of chronic mountain sickness (CMS). Methods: 14 patients with CMS and 15 patients with simple old fracture were divided into CMS group and control group, respectively.Bone marrow mononuclear cells (BMMNC) were separated, marked with CD71 monoclonal antibody and stained with Annexin V-FITC/PI.Then the apoptotic index of CD71(+) nucleated erythrocytes was determined by flow cytometry.CD71(+) nucleated erythrocytes were sorted out by magnetic column separation, and Cyt-C mRNA was detected by RT-qPCR, MMP was detected by JC-1 staining flow cytometry. Results: The apoptotic index of CD71(+) nucleated erythrocytes was (1.9±1.4)% in the CMS group, and was (3.2±1.5)% in the control group, with significant difference between the two groups ( P C mRNA was (0.72±0.14) in the CMS group, and was (1.00±0.15) in the control group, with significant difference between the two groups ( P C mRNA. Conclusions: The apoptosis index of CD71(+) nucleated erythrocytes decreased in CMS patients, which was negatively correlated with the level of hemoglobin, indicating that the decline of apoptosis index of CD71(+) nucleated erythrocytes may be related to the accumulation of red blood cells in CMS.The MMP increased and Cyt-C mRNA expression decreased in CD71(+) nucleated erythrocytes of CMS patients, which suggests that the change of mitochondrial pathway of apoptosis might be involved in the down-regulation of CD71(+) nucleated erythrocytes apoptosis in CMS patients.But there was no significant correlation among CD71(+) nucleated erythrocyte apoptosis index, MMP and Cyt-C mRNA levels, which indicates that the mechanism of CD71(+) nucleated erythrocytes apoptosis is complex in CMS.

  14. A facile method for simulating randomly rough membrane surface associated with interface behaviors

    Science.gov (United States)

    Qu, Xiaolu; Cai, Xiang; Zhang, Meijia; Lin, Hongjun; Leihong, Zhao; Liao, Bao-Qiang

    2018-01-01

    Modeling rough surfaces has emerged as a distinct discipline of considerable research interest in interface behaviors including membrane fouling. In this paper, a facile method was proposed to simulate rough membrane surface morphology. Natural membrane surface was found to be randomly rough, and its height distribution obeys Gaussian distribution. A new method which combines spectrum method, Gaussian distribution and Fourier transform technique was deduced. Simulation of the rough membrane surface showed high similarity in terms of statistical roughness and height distribution between the simulated surface and the real membrane surface, indicating feasibility of the new method. It was found that, correlation length (l) and the number of superposed ridges (N) are key parameters affecting the simulated membrane surface morphology. This new method has evident advantages over conventional modeling methods The proposed method for randomly rough membrane surface modeling could be potentially used to quantify the interfacial interactions between two rough surfaces, giving implications for membrane fouling mitigation.

  15. Olive Oil-related Anti-inflammatory Effects on Atherosclerosis: Potential Clinical Implications.

    Science.gov (United States)

    Wongwarawipat, Tanakal; Papageorgiou, Nikolaos; Bertsias, Dimitrios; Siasos, Gerasimos; Tousoulis, Dimitris

    2018-01-01

    Atherosclerosis is characterized by a chronic low-grade inflammatory process which can result in atherothrombosis and a number of cardiovascular diseases (CVD). It is believed to be caused by multiple processes that involve inflammation and immunity. Mediterranean Diet (MedD) has been discovered to possess anti-inflammatory properties and associated with a reduction in the CVD risk and mortality. Its main component, extra-virgin olive oil (EVOO), is believed to be largely responsible for these effects and therefore, has been investigated in various studies. The present review article aims to summarize the available literature on the antiinflammatory and cardio-protective effects of EVOO. A search based on the key concepts "olive oil", "atherosclerosis", "inflammation" and "cardiovascular disease" was performed to retrieve relevant studies and articles on the association between the consumption of EVOO and the levels of inflammatory biomarkers as well as CVD incidence and mortality from online databases; Pubmed, Embase and Cochrane Library. Consumption of EVOO is associated with a reduction in inflammatory biomarkers and molecules implicated in atherosclerosis as well as CVD incidence and mortality as well as other complications such as heart failure and atrial fibrillation. Moreover, these anti-inflammatory and cardioprotective effects of EVOO are mostly attributable to its high content of polyphenol molecules. Currently available evidence supports the anti-inflammatory and cardio-protective roles of EVOO. However, there is limited amount of available randomized controlled trials especially lacking those investigating the use of EVOO as secondary prevention, heterogeneity of study design, limited generalization to wide population groups, and inability to determine the minimum intake of EVOO required to clinically achieve the anti-inflammatory and cardioprotective effects. Therefore, more highquality randomized controlled trials still need to be carried out to

  16. Potentiation of the effect of thiazide derivatives by carbonic anhydrase inhibitors: molecular mechanisms and potential clinical implications.

    Directory of Open Access Journals (Sweden)

    Kamyar Zahedi

    Full Text Available Carbonic anhydrase inhibitors (CAI are mild diuretics, hence not widely used in fluid overloaded states. They are however the treatment of choice for certain non-kidney conditions. Thiazides, specific inhibitors of Na-Cl cotransport (NCC, are mild agents and the most widely used diuretics in the world for control of mild hypertension.In addition to inhibiting the salt reabsorption in the proximal tubule, CAIs down-regulate pendrin, therefore leaving NCC as the major salt absorbing transporter in the distal nephron, and hence allowing for massive diuresis by the inhibitors of NCC in the setting of increased delivery of salt from the proximal tubule.Daily treatment of rats with acetazolamide (ACTZ, a known CAI, for 10 days caused mild diuresis whereas daily treatment with hydrochlorothiazide (HCTZ for 4 days caused hardly any diuresis. However, treatment of rats that were pretreated with ACTZ for 6 days with a combination of ACTZ plus HCTZ for 4 additional days increased the urine output by greater than 2 fold (p<0.001, n = 5 compared to ACTZ-treated animals. Sodium excretion increased by 80% in the ACTZ plus HCTZ group and animals developed significant volume depletion, metabolic alkalosis and pre-renal failure. Molecular studies demonstrated ∼75% reduction in pendrin expression by ACTZ. The increased urine output in ACTZ/HCTZ treated rats was associated with a significant reduction in urine osmolality and reduced membrane localization of AQP-2 (aquaporin2.These results indicate that ACTZ down-regulates pendrin expression and leaves NCC as the major salt absorbing transporter in the distal nephron in the setting of increased delivery of salt from the proximal tubule. Despite being considered mild agents individually, we propose that the combination of ACTZ and HCTZ is a powerful diuretic regimen.

  17. Response to the call by DCMS for views on the potential implications of Brexit for Data Protection stakeholders: Brexit: Potential Implications for Digital and ‘Fintech’ Industries

    OpenAIRE

    Mc Cullagh, Karen

    2016-01-01

    Following the outcome of the historic ‘Brexit’ referendum on 23rd June 2016 in which a majority of eligible voters in the UK voted to ‘Leave,’[1] the United Kingdom is potentially on course to leave the European Union,[2] but to ensure continued economic success it will seek to maintain a favourable trading relationship with the EU. This article identifies and critically evaluates the various types of trade deals the UK might negotiate upon exit with a particular focus on trade in services si...

  18. The relationship between mothers' child abuse potential and current mental health symptoms: implications for screening and referral.

    Science.gov (United States)

    Rinehart, Deborah J; Becker, Marion A; Buckley, Pamela R; Dailey, Kathy; Reichardt, Charles S; Graeber, Carla; VanDeMark, Nancy R; Brown, Ellen

    2005-01-01

    This analysis examined data from mothers at 2 of the 9 sites participating in Substance Abuse and Mental Health Services Administration's (SAMHSA's) national Women Co-occurring Disorders and Violence Study (WCDVS). According to previous literature, it was hypothesized that women in the WCDVS would be at high risk of perpetrating child abuse. This research examined mothers' potential for physical child abuse and assessed the association between child abuse potential, current mental health symptoms, alcohol and drug use severity, and trauma. Results revealed that participants had significant potential for child abuse. Hierarchical regression analyses revealed that current mental health symptoms were the strongest predictor of mothers' scores on the Child Abuse Potential (CAP) Inventory. This study highlights the important relationships between commonly used instruments across the mental health, substance, and child welfare fields and the potential dual use of these instruments. Implications for policy and practice are discussed.

  19. Effect of the Phase Volume Ratio on the Potential of a Liquid-Membrane Ion-Selective Electrode

    Czech Academy of Sciences Publication Activity Database

    Samec, Zdeněk; Girault, H. H.

    2004-01-01

    Roč. 76, č. 14 (2004), s. 4150-4155 ISSN 0003-2700 R&D Projects: GA MŠk ME 502 Institutional research plan: CEZ:AV0Z4040901 Keywords : liquit-membrane * ion-selective electrode * two.phase liquid system Subject RIV: CG - Electrochemistry Impact factor: 5.450, year: 2004

  20. Modeling Transmembrane Domain Dimers/Trimers of Plexin Receptors: Implications for Mechanisms of Signal Transmission across the Membrane

    Science.gov (United States)

    Zhang, Liqun; Polyansky, Anton; Buck, Matthias

    2015-01-01

    Single-pass transmembrane (TM) receptors transmit signals across lipid bilayers by helix association or by configurational changes within preformed dimers. The structure determination for such TM regions is challenging and has mostly been accomplished by NMR spectroscopy. Recently, the computational prediction of TM dimer structures is becoming recognized for providing models, including alternate conformational states, which are important for receptor regulation. Here we pursued a strategy to predict helix oligomers that is based on packing considerations (using the PREDDIMER webserver) and is followed by a refinement of structures, utilizing microsecond all-atom molecular dynamics simulations. We applied this method to plexin TM receptors, a family of 9 human proteins, involved in the regulation of cell guidance and motility. The predicted models show that, overall, the preferences identified by PREDDIMER are preserved in the unrestrained simulations and that TM structures are likely to be diverse across the plexin family. Plexin-B1 and –B3 TM helices are regular and tend to associate, whereas plexin-A1, -A2, –A3, -A4, -C1 and –D1 contain sequence elements, such as poly-Glycine or aromatic residues that distort helix conformation and association. Plexin-B2 does not form stable dimers due to the presence of TM prolines. No experimental structural information on the TM region is available for these proteins, except for plexin-C1 dimeric and plexin-B1 – trimeric structures inferred from X-ray crystal structures of the intracellular regions. Plexin-B1 TM trimers utilize Ser and Thr sidechains for interhelical contacts. We also modeled the juxta-membrane (JM) region of plexin-C1 and plexin-B1 and show that it synergizes with the TM structures. The structure and dynamics of the JM region and TM-JM junction provide determinants for the distance and distribution of the intracellular domains, and for their binding partners relative to the membrane. The structures

  1. Human transporters, PEPT1/2, facilitate melatonin transportation into mitochondria of cancer cells: An implication of the therapeutic potential.

    Science.gov (United States)

    Huo, Xiaokui; Wang, Chao; Yu, Zhenlong; Peng, Yulin; Wang, Shumei; Feng, Shengnan; Zhang, Shouji; Tian, Xiangge; Sun, Chengpeng; Liu, Kexin; Deng, Sa; Ma, Xiaochi

    2017-05-01

    Melatonin is present in virtually all organisms from bacteria to mammals, and it exhibits a broad spectrum of biological functions, including synchronization of circadian rhythms and oncostatic activity. Several functions of melatonin are mediated by its membrane receptors, but others are receptor-independent. For the latter, melatonin is required to penetrate membrane and enters intracellular compartments. However, the mechanism by which melatonin enters cells remains debatable. In this study, it was identified that melatonin and its sulfation metabolites were the substrates of oligopeptide transporter (PEPT) 1/2 and organic anion transporter (OAT) 3, respectively. The docking analysis showed that the binding of melatonin to PEPT1/2 was attributed to their low binding energy and suitable binding conformation in which melatonin was embedded in the active site of PEPT1/2 and fitted well with the cavity in three-dimensional space. PEPT1/2 transporters play a pivotal role in melatonin uptake in cells. Melatonin's membrane transportation via PEPT1/2 renders its oncostatic effect in malignant cells. For the first time, PEPT1/2 were identified to localize in the mitochondrial membrane of human cancer cell lines of PC3 and U118. PEPT1/2 facilitated the transportation of melatonin into mitochondria. Melatonin accumulation in mitochondria induced apoptosis of PC3 and U118 cells. Thus, PEPT1/2 can potentially be used as a cancer cell-targeted melatonin delivery system to improve the therapeutic effects of melatonin in cancer treatment. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. A pilot-scale forward osmosis membrane system for concentrating low-strength municipal wastewater: performance and implications

    Science.gov (United States)

    Wang, Zhiwei; Zheng, Junjian; Tang, Jixu; Wang, Xinhua; Wu, Zhichao

    2016-02-01

    Recovery of nutrients and energy from municipal wastewater has attracted much attention in recent years; however, its efficiency is significantly limited by the low-strength properties of municipal wastewater. Herein, we report a pilot-scale forward osmosis (FO) system using a spiral-wound membrane module to concentrate real municipal wastewater. Under active layer facing feed solution mode, the critical concentration factor (CCF) of this FO system was determined to be 8 with 0.5 M NaCl as draw solution. During long-term operation at a concentration factor of 5, (99.8 ± 0.6)% of chemical oxygen demand and (99.7 ± 0.5)% of total phosphorus rejection rates could be achieved at a flux of 6 L/(m2 h) on average. In comparison, only (48.1 ± 10.5)% and (67.8 ± 7.3)% rejection of ammonium and total nitrogen were observed. Cake enhanced concentration polarization is a major contributor to the decrease of water fluxes. The fouling also led to the occurrence of a cake reduced concentration polarization effect, improving ammonium rejection rate with the increase of operation time in each cycle. This work demonstrates the applicability of using FO process for wastewater concentrating and also limitations in ammonium recovery that need further improvement in future.

  3. A pilot-scale forward osmosis membrane system for concentrating low-strength municipal wastewater: performance and implications

    Science.gov (United States)

    Wang, Zhiwei; Zheng, Junjian; Tang, Jixu; Wang, Xinhua; Wu, Zhichao

    2016-01-01

    Recovery of nutrients and energy from municipal wastewater has attracted much attention in recent years; however, its efficiency is significantly limited by the low-strength properties of municipal wastewater. Herein, we report a pilot-scale forward osmosis (FO) system using a spiral-wound membrane module to concentrate real municipal wastewater. Under active layer facing feed solution mode, the critical concentration factor (CCF) of this FO system was determined to be 8 with 0.5 M NaCl as draw solution. During long-term operation at a concentration factor of 5, (99.8 ± 0.6)% of chemical oxygen demand and (99.7 ± 0.5)% of total phosphorus rejection rates could be achieved at a flux of 6 L/(m2 h) on average. In comparison, only (48.1 ± 10.5)% and (67.8 ± 7.3)% rejection of ammonium and total nitrogen were observed. Cake enhanced concentration polarization is a major contributor to the decrease of water fluxes. The fouling also led to the occurrence of a cake reduced concentration polarization effect, improving ammonium rejection rate with the increase of operation time in each cycle. This work demonstrates the applicability of using FO process for wastewater concentrating and also limitations in ammonium recovery that need further improvement in future. PMID:26898640

  4. A pilot-scale forward osmosis membrane system for concentrating low-strength municipal wastewater: performance and implications.

    Science.gov (United States)

    Wang, Zhiwei; Zheng, Junjian; Tang, Jixu; Wang, Xinhua; Wu, Zhichao

    2016-02-22

    Recovery of nutrients and energy from municipal wastewater has attracted much attention in recent years; however, its efficiency is significantly limited by the low-strength properties of municipal wastewater. Herein, we report a pilot-scale forward osmosis (FO) system using a spiral-wound membrane module to concentrate real municipal wastewater. Under active layer facing feed solution mode, the critical concentration factor (CCF) of this FO system was determined to be 8 with 0.5 M NaCl as draw solution. During long-term operation at a concentration factor of 5, (99.8 ± 0.6)% of chemical oxygen demand and (99.7 ± 0.5)% of total phosphorus rejection rates could be achieved at a flux of 6 L/(m(2) h) on average. In comparison, only (48.1 ± 10.5)% and (67.8 ± 7.3)% rejection of ammonium and total nitrogen were observed. Cake enhanced concentration polarization is a major contributor to the decrease of water fluxes. The fouling also led to the occurrence of a cake reduced concentration polarization effect, improving ammonium rejection rate with the increase of operation time in each cycle. This work demonstrates the applicability of using FO process for wastewater concentrating and also limitations in ammonium recovery that need further improvement in future.

  5. Volunteering for College? Potential Implications of Financial Aid Tax Credits Rewarding Community Service

    Science.gov (United States)

    Wells, Ryan S.; Lynch, Cassie M.

    2014-01-01

    President Obama has proposed a financial aid policy whereby students who complete 100 hours of community service would receive a tax credit of US$4,000 for college. After lawmakers cut this proposal from previous legislation, the administration was tasked with studying the feasibility of implementation. However, the implications of the policy for…

  6. Indoor and outdoor airborne particles : an in vitro study on mutagenic potential and toxicological implications

    NARCIS (Netherlands)

    Houdt, van J.J.

    1988-01-01

    Introduction

    Air pollution components are present as gases and as particulate matter. As particle deposition takes place in various parts of the respiratory system particulate matter may have other toxicological implications than gaseous pollutants, which all may

  7. Ciprofloxacin provokes SOS-dependent changes in respiration and membrane potential and causes alterations in the redox status of Escherichia coli.

    Science.gov (United States)

    Smirnova, Galina V; Tyulenev, Aleksey V; Muzyka, Nadezda G; Peters, Mikhail A; Oktyabrsky, Oleg N

    2017-01-01

    An in-depth understanding of the physiological response of bacteria to antibiotic-induced stress is needed for development of new approaches to combatting microbial infections. Fluoroquinolone ciprofloxacin causes phase alterations in Escherichia coli respiration and membrane potential that strongly depend on its concentration. Concentrations lower than the optimal bactericidal concentration (OBC) do not inhibit respiration during the first phase. A dose higher than the OBC provokes immediate SOS-independent inhibition of respiration and growth that can contribute to a decreased SOS response and lowered susceptibility to high concentrations of ciprofloxacin. Cells retain their metabolic activity, membrane potential and accelerated K + uptake and produce low levels of superoxide and H 2 O 2 during the first phase. The time before initiation of the second phase is inversely correlated with the ciprofloxacin concentration. The second phase is SOS-dependent and characterized by respiratory inhibition, membrane depolarization, K + and glutathione leakage and cessation of glucose consumption and may be considered as cell death. atpA, gshA and kefBkefC knockouts, which perturb fluxes of protons and K + , can modify the degree and duration of respiratory inhibition and potassium retention. Loss of K + efflux channels KefB and KefC enhances the susceptibility of E. coli to ciprofloxacin. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  8. A non-inactivating high-voltage-activated two-pore Na+ channel that supports ultra-long action potentials and membrane bistability

    Science.gov (United States)

    Cang, Chunlei; Aranda, Kimberly; Ren, Dejian

    2014-09-01

    Action potentials (APs) are fundamental cellular electrical signals. The genesis of short APs lasting milliseconds is well understood. Ultra-long APs (ulAPs) lasting seconds to minutes also occur in eukaryotic organisms, but their biological functions and mechanisms of generation are largely unknown. Here, we identify TPC3, a previously uncharacterized member of the two-pore channel protein family, as a new voltage-gated Na+ channel (NaV) that generates ulAPs, and that establishes membrane potential bistability. Unlike the rapidly inactivating NaVs that generate short APs in neurons, TPC3 has a high activation threshold, activates slowly and does not inactivate—three properties that help generate long-lasting APs and guard the membrane against unintended perturbation. In amphibian oocytes, TPC3 forms a channel similar to channels induced by depolarization and sperm entry into eggs. TPC3 homologues are present in plants and animals, and they may be important for cellular processes and behaviours associated with prolonged membrane depolarization.

  9. Mechanism of ROS scavenging and antioxidant signalling by redox metallic and fullerene nanomaterials: Potential implications in ROS associated degenerative disorders.

    Science.gov (United States)

    Akhtar, Mohd Javed; Ahamed, Maqusood; Alhadlaq, Hisham A; Alshamsan, Aws

    2017-04-01

    The balance between oxidation and anti-oxidation is believed to be critical in maintaining healthy biological systems. However, our endogenous antioxidant defense systems are incomplete without exogenous antioxidants and, therefore, there is a continuous demand for exogenous antioxidants to prevent stress and ageing associated disorders. Nanotechnology has yielded enormous variety of nanomaterials (NMs) of which metallic and carbonic (mainly fullerenes) NMs, with redox property, have been found to be strong scavengers of ROS and antioxidants in preclinical in vitro and in vivo models. Redox activity of metal based NMs and membrane translocation time of fullerene NMs seem to be the major determinants in ROS scavenging potential exhibited by these NMs. A comprehensive knowledge about the effects of ROS scavenging NMs in cellular antioxidant signalling is largely lacking. This review compiles the mechanisms of ROS scavenging as well as antioxidant signalling of the aforementioned metallic and fullerene NMs. Direct interaction between NMs and proteins does greatly affect the corona/adsorption formation dynamics but such interaction does not provide the explanation behind diverse biological outcomes induced by NMs. Indirect interaction, however, that could occur via NMs uptake and dissolution, NMs ROS induction and ROS scavenging property, and NMs membrane translocation time seem to work as a central mode of interaction. The usage of potential antioxidant NMs in biological systems would greatly impact the field of nanomedicine. ROS scavenging NMs hold great promise in the future treatment of ROS related degenerative disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Membrane-initiated non-genomic signaling by estrogens in the hypothalamus: cross-talk with glucocorticoids with implications for behavior

    Directory of Open Access Journals (Sweden)

    Jennifer eRainville

    2015-02-01

    Full Text Available The estrogen receptor (ER and glucocorticoid receptor (GR are members of the nuclear receptor superfamily that can signal using both non-genomic and genomic transcriptional modes. Though genomic modes of signaling have been well characterized and several behaviors attributed to this signaling mechanism, the physiological significance of non-genomic modes of signaling has not been well understood. This has partly been due to the controversy regarding the identity of the membrane ER (mER or membrane GR (mGR that may mediate rapid, non-genomic signaling and the downstream signaling cascades that may result as a consequence of steroid ligands binding the mER or the mGR. Both estrogens and glucocorticoids exert a number of actions on the hypothalamus, including feedback. This review focuses on the various candidates for the mER or mGR in the hypothalamus and the contribution of non-genomic signaling to classical hypothalamically-driven behaviors and changes in neuronal morphology. It also attempts to categorize some of the possible functions of non-genomic signaling at both the cellular level and at the organismal level that are relevant for behavior, including some behaviors that are regulated by both estrogens and glucocorticoids in a potentially synergistic manner. Lastly, it attempts to show that steroid signaling via non-genomic modes may provide the organism with rapid behavioral responses to stimuli.

  11. The “Funny” Current (If Inhibition by Ivabradine at Membrane Potentials Encompassing Spontaneous Depolarization in Pacemaker Cells

    Directory of Open Access Journals (Sweden)

    Yael Yaniv

    2012-07-01

    Full Text Available Recent clinical trials have shown that ivabradine (IVA, a drug that inhibits the funny current (If in isolated sinoatrial nodal cells (SANC, decreases heart rate and reduces morbidity and mortality in patients with cardiovascular diseases. While IVA inhibits If, this effect has been reported at essentially unphysiological voltages, i.e., those more negative than the spontaneous diastolic depolarization (DD between action potentials (APs. We tested the relative potency of IVA to block If over a wide range of membrane potentials, including those that encompass DD governing to the SANC spontaneous firing rate. A clinically relevant IVA concentration of 3 μM to single, isolated rabbit SANC slowed the spontaneous AP firing rate by 15%. During voltage clamp the maximal If was 18 ± 3 pA/pF (at −120 mV and the maximal If reduction by IVA was 60 ± 8% observed at −92 ± 4 mV. At the maximal diastolic depolarization (~−60 mV If amplitude was only −2.9 ± 0.4 pA/pF, and was reduced by only 41 ± 6% by IVA. Thus, If amplitude and its inhibition by IVA at physiologically relevant membrane potentials are substantially less than that at unphysiological (hyperpolarized membrane potentials. This novel finding more accurately describes how IVA affects SANC function and is of direct relevance to numerical modeling of SANC automaticity.

  12. Rare mutations and potentially damaging missense variants in genes encoding fibrillar collagens and proteins involved in their production are candidates for risk for preterm premature rupture of membranes.

    Directory of Open Access Journals (Sweden)

    Bhavi P Modi

    Full Text Available Preterm premature rupture of membranes (PPROM is the leading identifiable cause of preterm birth with ~ 40% of preterm births being associated with PPROM and occurs in 1% - 2% of all pregnancies. We hypothesized that multiple rare variants in fetal genes involved in extracellular matrix synthesis would associate with PPROM, based on the assumption that impaired elaboration of matrix proteins would reduce fetal membrane tensile strength, predisposing to unscheduled rupture. We performed whole exome sequencing (WES on neonatal DNA derived from pregnancies complicated by PPROM (49 cases and healthy term deliveries (20 controls to identify candidate mutations/variants. Genotyping for selected variants from the WES study was carried out on an additional 188 PPROM cases and 175 controls. All mothers were self-reported African Americans, and a panel of ancestry informative markers was used to control for genetic ancestry in all genetic association tests. In support of the primary hypothesis, a statistically significant genetic burden (all samples combined, SKAT-O p-value = 0.0225 of damaging/potentially damaging rare variants was identified in the genes of interest-fibrillar collagen genes, which contribute to fetal membrane strength and integrity. These findings suggest that the fetal contribution to PPROM is polygenic, and driven by an increased burden of rare variants that may also contribute to the disparities in rates of preterm birth among African Americans.

  13. Plasma-stimulated medium kills TRAIL-resistant human malignant cells by promoting caspase-independent cell death via membrane potential and calcium dynamics modulation.

    Science.gov (United States)

    Tokunaga, Tomohiko; Ando, Takashi; Suzuki-Karasaki, Miki; Ito, Tomohisa; Onoe-Takahashi, Asuka; Ochiai, Toyoko; Soma, Masayoshi; Suzuki-Karasaki, Yoshihiro

    2018-03-01

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and cold plasma-stimulated medium (PSM) have been shown to exhibit tumor-selective cytotoxicity and have emerged as promising new tools for cancer treatment. However, to date, at least to the best of our knowledge, no data are available as to which substance is more potent in killing cancer cells. Thus, in this study, we systematically compared their abilities to kill human malignant cells from different origins. We found that PSM dose-dependently killed TRAIL-resistant melanoma, osteosarcoma and neuroblastoma cells. Moreover, PSM had little cytotoxicity toward osteoblasts. PSM was more potent than TRAIL in inducing caspase-3/7 activation, mitochondrial network aberration and caspase-independent cell death. We also found that PSM was more potent in inducing plasma membrane depolarization (PMD) and disrupting endoplasmic-mitochondrial Ca2+ homeostasis. Moreover, persistent PMD was caused by different membrane-depolarizing agents; the use of the anti-type II diabetes drug, glibenclamide, alone caused mitochondrial fragmentation and enhanced TRAIL-induced Ca2+ modulation, mitochondrial network abnormalities and caspase-independent cell killing. These results demonstrate that PSM has a therapeutic advantage over TRAIL owing to its greater capacity to evoke caspase-independent cell death via mitochondrial network aberration by disrupting membrane potential and Ca2+ homeostasis. These findings may provide a strong rationale for developing PSM as a novel approach for the treatment of TRAIL-resistant malignant cells.

  14. Rare mutations and potentially damaging missense variants in genes encoding fibrillar collagens and proteins involved in their production are candidates for risk for preterm premature rupture of membranes.

    Science.gov (United States)

    Modi, Bhavi P; Teves, Maria E; Pearson, Laurel N; Parikh, Hardik I; Chaemsaithong, Piya; Sheth, Nihar U; York, Timothy P; Romero, Roberto; Strauss, Jerome F

    2017-01-01

    Preterm premature rupture of membranes (PPROM) is the leading identifiable cause of preterm birth with ~ 40% of preterm births being associated with PPROM and occurs in 1% - 2% of all pregnancies. We hypothesized that multiple rare variants in fetal genes involved in extracellular matrix synthesis would associate with PPROM, based on the assumption that impaired elaboration of matrix proteins would reduce fetal membrane tensile strength, predisposing to unscheduled rupture. We performed whole exome sequencing (WES) on neonatal DNA derived from pregnancies complicated by PPROM (49 cases) and healthy term deliveries (20 controls) to identify candidate mutations/variants. Genotyping for selected variants from the WES study was carried out on an additional 188 PPROM cases and 175 controls. All mothers were self-reported African Americans, and a panel of ancestry informative markers was used to control for genetic ancestry in all genetic association tests. In support of the primary hypothesis, a statistically significant genetic burden (all samples combined, SKAT-O p-value = 0.0225) of damaging/potentially damaging rare variants was identified in the genes of interest-fibrillar collagen genes, which contribute to fetal membrane strength and integrity. These findings suggest that the fetal contribution to PPROM is polygenic, and driven by an increased burden of rare variants that may also contribute to the disparities in rates of preterm birth among African Americans.

  15. Decrease of Na, K-ATPase Electrogenic Contribution and Resting Membrane Potential of Rat Soleus after 3 Days of Hindlimb Unloading

    Science.gov (United States)

    Krivoi, I. I.; Kravtsova, V. V.; Drabkina, T. M.; Prokofiev, A. V.; Nikolsky, E. E.; Shenkman, B. S.

    2008-06-01

    The Na,K-ATPase activity is critically important for excitability, electrogenesis and contractility of skeletal muscle expressing ? and ? isoforms of the enzyme [6, 9]. It is well known that disuse induced by hindlimb unloading (HU) leads to progressive atrophy of skeletal muscle; the muscle undergoes a number of dramatic remodeling events. In particular, changes in ion channel expression in response to muscle unweighting were observed [1, 8]. Decrease of resting membrane potential (RMP), electrogenic contribution of Na,K-ATPase and membrane resistance during 7-28 days of HU was shown [8, 10]. The intrinsic mechanisms involved in the process have not been revealed until present. At the same time, the understanding of these mechanisms could be crucial for the disclosing the mechanisms underlying the resting Ca2+ accumulation in the cytoplasm of the unloaded muscle [3, 7]. In the present study, the effect of early (3 days) HU-induced disuse of slow-twitch soleus muscle on membrane electrogenesis as well as on electrogenic contribution of Na,K-ATPase isoforms was investigated.

  16. Identification and characterization of muscarinic receptors potentiating the stimulation of adenylyl cyclase activity by corticotropin-releasing hormone in membranes of rat frontal cortex.

    Science.gov (United States)

    Onali, P; Olianas, M C

    1998-08-01

    In membranes of the rat frontal cortex, acetylcholine (ACh) and other cholinergic agonists were found to potentiate the stimulation of adenylyl cyclase activity elicited by corticotropin-releasing hormone (CRH). Oxotremorine-M, carbachol and methacholine were as effective as ACh, whereas oxotremorine and arecoline were much less effective. The facilitating effect of Ach was potently blocked by the M1 antagonists R-trihexyphenidyl, telenzepine and pirenzepine and by the M3 antagonists hexahydro-sila-difenidol and p-fluorohexahydro-sila-difenidol, whereas the M2 and M4 antagonists himbacine, methoctramine, AF-DX 116 and AQ-RA 741 were less potent. The mamba venom toxin MT-1, which binds with high affinity to M1 receptors, was also a potent blocker. The pharmacological profile of the muscarinic potentiation of CRH receptor activity was markedly different from that displayed by the muscarinic inhibition of forskolin-stimulated adenylyl cyclase, which could be detected in the same membrane preparations. Moreover, the intracerebral injection of pertussis toxin impaired the muscarinic inhibition of cyclic AMP formation and reduced the Ach stimulation of [35S]GTPgammaS binding to membrane G proteins but failed to affect the facilitating effect on CRH receptor activity. The latter response was also insensitive to the phospholipase C inhibitor U-73122, the protein kinase inhibitor staurosporine and to the inhibitors of arachidonic acid metabolism indomethacin and nordihydroguaiaretic acid. These data demonstrate that in the rat frontal cortex, muscarinic receptors of the M1 subtype potentiate CRH transmission by interacting with pertussis toxin-insensitive G proteins.

  17. Recent Progress in the Structure Determination of GPCRs, a Membrane Protein Family with High Potential as Pharmaceutical Targets

    Energy Technology Data Exchange (ETDEWEB)

    Cherezov, Vadim; Abola, Enrique; Stevens, Raymond C.

    2015-11-30

    G protein-coupled receptors (GPCRs) constitute a highly diverse and ubiquitous family of integral membrane proteins, transmitting signals inside the cells in response to an assortment of disparate extra-cellular stimuli. Their strategic location on the cell surface and their involvement in crucial cellular and physiological processes turn these receptors into highly important pharmaceutical targets. Recent technological developments aimed at stabilization and crystallization of these receptors have led to significant breakthroughs in GPCR structure determination efforts. One of the successful approaches involved receptor stabilization with the help of a fusion partner combined with crystallization in lipidic cubic phase (LCP). The success of using an LCP matrix for crystallization is generally attributed to the creation of a more native, membrane-like stabilizing environment for GPCRs just prior to nucleation and to the formation of type I crystal lattices, thus generating highly ordered and strongly diffracting crystals. Here they describe protocols for reconstituting purified GPCRs in LCP, performing pre-crystallization assays, setting up crystallization trials in manual mode, detecting crystallization hits, optimizing crystallization conditions, harvesting, and collecting crystallographic data. The protocols provide a sensible framework for approaching crystallization of stabilized GPCRs in LCP, however, as in any crystallization experiment, extensive screening and optimization of crystallization conditions as well as optimization of protein construct and purification steps are required. The process remains risky and these protocols do not necessarily guarantee success.

  18. Potentiating activity of luteolin on membrane permeabilizing agent and ATPase inhibitor against methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Joung, Dae-Ki; Lee, Young-Seob; Han, Sin-Hee; Lee, Sang-Won; Cha, Seon-Woo; Mun, Su-Hyun; Kong, Ryong; Kang, Ok-Hwa; Song, Ho-Jun; Shin, Dong-Won; Kwon, Dong-Yeul

    2016-01-01

    To investigate the mechanism of antibacterial activity of luteolin (LUT) against methicillin-resistant Staphylococcus aureus (MRSA). The mechanism of anti-MRSA activity of LUT was analyzed by the viability assay in membrane permeabilizing agent, ATPase inhibitors, and peptidoglycan (PGN) derived from Staphylococcus aureus (S. aureus). Also, transmission electron microscopy was used to monitor survival characteristics and changes in S. aureus morphology. Compared to the LUT alone, the optical density of suspensions treated with the combination of 125 μg/mL Tris and 250 μg/mL N,N'-dicyclohexylcarbodiimide were reduced to 60% and 46% of the control, respectively. PGN (15.6 μg/mL) gradually impeded the activity of LUT, and PGN (62.5 μg/mL) completely blocked the activity of LUT on S. aureus. Increased susceptibility to LUT with the Tris-dicyclohexylcarbodiimide combinations is evident in all tested MRSA isolates. The results indicate LUT synergy in increasing cytoplasmic membrane permeability and inhibiting ATPase. S. aureus PGN directly blocks the antibacterial activity of LUT, suggesting the direct binding of LUT with PGN. These findings may be validated for the development of antibacterial agent for low MRSA resistance. Copyright © 2016 Hainan Medical College. Production and hosting by Elsevier B.V. All rights reserved.

  19. Non-specific effects of vaccines: plausible and potentially important, but implications uncertain.

    Science.gov (United States)

    Pollard, Andrew J; Finn, Adam; Curtis, Nigel

    2017-11-01

    Non-specific effects (NSE) or heterologous effects of vaccines are proposed to explain observations in some studies that certain vaccines have an impact beyond the direct protection against infection with the specific pathogen for which the vaccines were designed. The importance and implications of such effects remain controversial. There are several known immunological mechanisms which could lead to NSE, since it is widely recognised that the generation of specific immunity is initiated by non-specific innate immune mechanisms that may also have wider effects on adaptive immune function. However, there are no published studies that demonstrate a mechanistic link between such immunological phenomena and clinically relevant NSE in humans. While it is highly plausible that some vaccines do have NSE, their magnitude and duration, and thus importance, remain uncertain. Although the WHO recently concluded that current evidence does not justify changes to immunisation policy, further studies of sufficient size and quality are needed to assess the importance of NSE for all-cause mortality. This could provide insights into vaccine immunobiology with important implications for infant health and survival. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  20. Linking Cellular Mechanisms to Behavior: Entorhinal Persistent Spiking and Membrane Potential Oscillations May Underlie Path Integration, Grid Cell Firing, and Episodic Memory

    Directory of Open Access Journals (Sweden)

    Michael E. Hasselmo

    2008-01-01

    Full Text Available The entorhinal cortex plays an important role in spatial memory and episodic memory functions. These functions may result from cellular mechanisms for integration of the afferent input to entorhinal cortex. This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration. The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.

  1. Fish oil curtails the human action potential dome in a heterogeneous manner: Implication for arrhythmogenesis

    NARCIS (Netherlands)

    Verkerk, Arie O.; den Ruijter, Hester M.; de Jonge, Nicolaas; Coronel, Ruben

    2009-01-01

    Omega-3 polyunsaturated fatty acids (omega3-PUFAs) from fish oil modulate various ion channels, including the L-type calcium current (I(Ca,L)). As a result, fish oil shortens the cardiac action potential and may cause a loss of the dome of the action potential (AP). Under conditions of increased

  2. India’s long-term growth potential and the implications for Australia

    OpenAIRE

    Ben Ralston; Wilson Au-Yeung; Bill Brummitt

    2011-01-01

    After 20 years of economic reform this article discusses India’s long-term growth potential and canvasses some of the challenges that Indian policy makers will need to overcome to realise this potential. Some of the consequences of India’s growth for Australia are also explored.

  3. Quantifying the Relationship Between Curvature and Electric Potential in Lipid Bilayers

    DEFF Research Database (Denmark)

    Bruhn, Dennis Skjøth; Lomholt, Michael Andersen; Khandelia, Himanshu

    2016-01-01

    Cellular membranes mediate vital cellular processes by being subject to curvature and transmembrane electrical potentials. Here we build upon the existing theory for flexoelectricity in liquid crystals to quantify the coupling between lipid bilayer curvature and membrane potentials. Using molecular...... and spontaneous curvature) and the applied membrane potentials. We show that biologically relevant membrane potentials can induce biologically relevant curva- tures corresponding to radii of around 500nm. The implications of flexoelectricity in lipid bilayers are thus likely to be of considerable consequence both...

  4. Endothelial extracellular vesicles modulate the macrophage phenotype: Potential implications in atherosclerosis.

    Science.gov (United States)

    He, Shaolin; Wu, Chun; Xiao, Junhui; Li, Dazhu; Sun, Ziyan; Li, Ming

    2018-02-21

    Endothelial cells (ECs) and macrophages engage in tight and specific interactions that play critical roles in cardiovascular homeostasis and the pathogenesis of atherosclerosis. Extracellular vesicles (EVs) are circular membrane fragments released from the endosomal compartment as exosomes or shed from the surfaces of the membranes of most cell types. Increasing evidence indicates that EVs play a pivotal role in cell-to-cell communication. However, the contribution of EVs, as determine by oxidized low-density lipoprotein (ox-LDL)-exposed and/or Kruppel-like factor 2 (KLF2)-transduced ECs in the interaction between vascular ECs and monocytes/ macrophages, which is a key event in atherosclerotic plaque development, has remained elusive. The present study demonstrates the characteristic impact of EVs from ox-LDL-treated and/or KLF2-transduced ECs on the monocyte/macrophage phenotype in vitro and in vivo.Q-PCR showed that both the atherosclerosis inducer ox-LDL and atheroprotective factor KLF2 regulated inflammation-associated microRNA-155 (miR-155) expression in human umbilical vein endothelial cells (HUVECs). Moreover, co-culture, immunofluorescence and flow cytometry revealed that miR-155 was enriched in ox-LDL-induced ECs-EVs and subsequently transferred to human monocytic THP1 cells, in which these vesicles enhance monocyte activation by shifting the monocytes/macrophages balance from anti-inflammatory M2 macrophages towards pro-inflammatory M1 macrophages; EVs from KLF2-expressing ECs suppressed monocyte activation by enhancing immunomodulatory responses and diminishing proinflammatory responses, which indicate the potent anti-inflammatory activities of these cells. Furthermore, oil-red staining showed that atherosclerotic lesions were reduced in mice that received EVs from KLF2-transduced ECs with decreased pro-inflammatory M1 macrophages and increased anti-inflammatory M2 macrophages, and this effect is at least partly due to the decreased expression of

  5. Clinical implications in the shift of syndecan-1 expression from the cell membrane to the cytoplasm in bladder cancer.

    Science.gov (United States)

    Miyake, Makito; Lawton, Adrienne; Dai, Yunfeng; Chang, Myron; Mengual, Lourdes; Alcaraz, Antonio; Goodison, Steve; Rosser, Charles J

    2014-02-13

    To determine the diagnostic and prognostic capability of urinary and tumoral syndecan-1 (SDC-1) levels in patients with cancer of the urinary bladder. SDC-1 levels were quantitated by enzyme-linked immunosorbent assay (ELISA) in 308 subjects (102 cancer subjects and 206 non-cancer subjects) to assess its diagnostic capabilities in voided urine. The performance of SDC-1 was evaluated using the area under the curve of a receiver operating characteristic curve. In addition, immunohistochemical (IHC) staining assessed SDC-1 protein expression in 193 bladder specimens (185 cancer subjects and 8 non-cancer subjects). Outcomes were correlated to SDC-1 levels. Mean urinary levels of SDC-1 did not differ between the cancer subjects and the non-cancer subjects, however, the mean urinary levels of SDC-1 were reduced in high-grade compared to low-grade disease (p SDC-1 in normal tissue, low-grade tumors and NMIBC, to a distinctly cytoplasmic localization in high-grade tumors and MIBC was observed in tissue specimens. Alone urinary SDC-1 may not be a diagnostic biomarker for bladder cancer, but its urinary levels and cellular localization were associated with the differentiation status of patients with bladder tumors. Further studies are warranted to define the potential role for SDC-1 in bladder cancer progression.

  6. The Implication of PGC-1α on Fatty Acid Transport across Plasma and Mitochondrial Membranes in the Insulin Sensitive Tissues

    Directory of Open Access Journals (Sweden)

    Elżbieta Supruniuk

    2017-11-01

    Full Text Available PGC-1α coactivator plays a decisive role in the maintenance of lipid balance via engagement in numerous metabolic processes (i.e., Krebs cycle, β-oxidation, oxidative phosphorylation and electron transport chain. It constitutes a link between fatty acids import and their complete oxidation or conversion into bioactive fractions through the coordination of both the expression and subcellular relocation of the proteins involved in fatty acid transmembrane movement. Studies on cell lines and/or animal models highlighted the existence of an upregulation of the total and mitochondrial FAT/CD36, FABPpm and FATPs content in skeletal muscle in response to PGC-1α stimulation. On the other hand, the association between PGC-1α level or activity and the fatty acids transport in the heart and adipocytes is still elusive. So far, the effects of PGC-1α on the total and sarcolemmal expression of FAT/CD36, FATP1, and FABPpm in cardiomyocytes have been shown to vary in relation to the type of PPAR that was coactivated. In brown adipose tissue (BAT PGC-1α knockdown was linked with a decreased level of lipid metabolizing enzymes and fatty acid transporters (FAT/CD36, FABP3, whereas the results obtained for white adipose tissue (WAT remain contradictory. Furthermore, dysregulation in lipid turnover is often associated with insulin intolerance, which suggests the coactivator's potential role as a therapeutic target.

  7. Extensive Lysine Methylation in Hyperthermophilic Crenarchaea: Potential Implications for Protein Stability and Recombinant Enzymes

    Directory of Open Access Journals (Sweden)

    Catherine H. Botting

    2010-01-01

    Full Text Available In eukarya and bacteria, lysine methylation is relatively rare and is catalysed by sequence-specific lysine methyltransferases that typically have only a single-protein target. Using RNA polymerase purified from the thermophilic crenarchaeum Sulfolobus solfataricus, we identified 21 methyllysines distributed across 9 subunits of the enzyme. The modified lysines were predominantly in α-helices and showed no conserved sequence context. A limited survey of the Thermoproteus tenax proteome revealed widespread modification with 52 methyllysines in 30 different proteins. These observations suggest the presence of an unusual lysine methyltransferase with relaxed specificity in the crenarchaea. Since lysine methylation is known to enhance protein thermostability, this may be an adaptation to a thermophilic lifestyle. The implications of this modification for studies and applications of recombinant crenarchaeal enzymes are discussed.

  8. Lipid content and composition of oocytes from five coral species: potential implications for future cryopreservation efforts.

    Directory of Open Access Journals (Sweden)

    Chiahsin Lin

    Full Text Available Given the previously documented importance of lipid concentration and composition in the successful cryopreservation of gorgonian corals, these parameters were assessed in oocytes of five species of scleractinian coral; Platygyra daedalea, Echinopora gemmacea, Echinophyllia aspera, Oxypora lacera and Astreopora expansa. Wax esters, phosphatidylethanolamine, phosphatidylcholine, and fatty acids were all measured at detectable levels, and the latter were produced at significantly elevated quantities in E. gemmacea, E. aspera, and O. lacera. On the other hand, phosphatidylethanolamine, phosphatidylcholine, and wax ester were found at significantly higher concentrations in A. expansa oocytes. Triacylglycerol was not present in any species. Interestingly, the total lipid content of oocytes from all five scleractinians was significantly lower than that of oocytes of two gorgonian species, Junceella juncea and Junceella fragilis. As higher total lipid concentrations may be correlated with greater degrees of cellular membrane fluidity at lower temperatures, it stands to reason that gorgonian coral oocytes may be more likely to survive the cryopreservation process than oocytes of scleractinian corals.

  9. Environmental Life Cycle Assessment and Cost Analysis of Bath, NY Wastewater Treatment Plant: Potential Upgrade Implications

    Science.gov (United States)

    Many communities across the U.S. are required to upgrade wastewater treatment plants (WWTP) to meet increasingly stringent nutrient effluent standards. However, increased capital, energy and chemical requirements of upgrades create potential trade-offs between eutrophication pot...

  10. Novel secreted isoform of adhesion molecule ICAM-4: Potential regulator of membrane-associated ICAM-4 interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gloria; Spring, Frances A.; Parons, Stephen F.; Mankelow, Tosti J.; Peters, Luanne L.; Koury, Mark J.; Mohandas, Narla; Anstee, David J.; Chasis, Joel Anne

    2003-02-18

    ICAM-4, a newly characterized adhesion molecule, is expressed early in human erythropoiesis and functions as a ligand for binding a4b1 and aV integrin-expressing cells. Within the bone marrow, erythroblasts surround central macrophages forming erythroblastic islands. Evidence suggests that these islands are highly specialized subcompartments where cell adhesion events, in concert with cytokines, play critical roles in regulating erythropoiesis and apoptosis. Since erythroblasts express a4b1 and ICAM-4 and macrophages exhibit aV, ICAM-4 is an attractive candidate for mediating cellular interactions within erythroblastic islands. To determine whether ICAM-4 binding properties are conserved across species, we first cloned and sequenced the murine homologue. The translated amino acid sequence showed 68 percent overall identity with human ICAM-4. Using recombinant murine ICAM-4 extracellular domains, we discovered that hematopoietic a4b1-expressing HEL cells and non-hematopoietic aV-expressing FLY cells adhered to mouse ICAM-4. Cell adhesion studies showed that FLY and HEL cells bound to mouse and human proteins with similar avidity. These data strongly suggest conservation of integrin-binding properties across species. Importantly, we characterized a novel second splice cDNA that would be predicted to encode an ICAM-4 isoform, lacking the membrane-spanning domain. Erythroblasts express both isoforms of ICAM-4. COS-7 cells transfected with GFP constructs of prototypic or novel ICAM-4 cDNA showed different cellular localization patterns. Moreover, analysis of tissue culture medium revealed that the novel ICAM-4 cDNA encodes a secreted protein. We postulate that secretion of this newly described isoform, ICAM-4S, may modulate binding of membrane-associated ICAM-4 and could thus play a critical regulatory role in erythroblast molecular attachments.

  11. The 2008 Financial Crisis and Potential Output in Asia : Impact and Policy Implications

    OpenAIRE

    Cyn-Young Park; Ruperto P. Majuca; Josef T. Yap

    2010-01-01

    Monitoring the behavior of potential output helps policymakers implement appropriate policies in response to an economic crisis. In the short-run, estimates of the output gap can guide the timing of the implementation and withdrawal of stimulus measures. In the medium- to long-term, these estimates can also provide the basis for gauging productive potential and, hence, guide policies to support sustainable, non-inflationary output growth. In this paper, we investigate the post-crisis behavior...

  12. Bioelectric patterning during oogenesis: stage-specific distribution of membrane potentials, intracellular pH and ion-transport mechanisms in Drosophila ovarian follicles.

    Science.gov (United States)

    Krüger, Julia; Bohrmann, Johannes

    2015-01-16

    Bioelectric phenomena have been found to exert influence on various developmental and regenerative processes. Little is known about their possible functions and the cellular mechanisms by which they might act during Drosophila oogenesis. In developing follicles, characteristic extracellular current patterns and membrane-potential changes in oocyte and nurse cells have been observed that partly depend on the exchange of protons, potassium ions and sodium ions. These bioelectric properties have been supposed to be related to various processes during oogenesis, e. g. pH-regulation, osmoregulation, cell communication, cell migration, cell proliferation, cell death, vitellogenesis and follicle growth. Analysing in detail the spatial distribution and activity of the relevant ion-transport mechanisms is expected to elucidate the roles that bioelectric phenomena play during oogenesis. To obtain an overview of bioelectric patterning along the longitudinal and transversal axes of the developing follicle, the spatial distributions of membrane potentials (Vmem), intracellular pH (pHi) and various membrane-channel proteins were studied systematically using fluorescent indicators, fluorescent inhibitors and antisera. During mid-vitellogenic stages 9 to 10B, characteristic, stage-specific Vmem-patterns in the follicle-cell epithelium as well as anteroposterior pHi-gradients in follicle cells and nurse cells were observed. Corresponding distribution patterns of proton pumps (V-ATPases), voltage-dependent L-type Ca(2+)-channels, amiloride-sensitive Na(+)-channels and Na(+),H(+)-exchangers (NHE) and gap-junction proteins (innexin 3) were detected. In particular, six morphologically distinguishable follicle-cell types are characterized on the bioelectric level by differences concerning Vmem and pHi as well as specific compositions of ion channels and carriers. Striking similarities between Vmem-patterns and activity patterns of voltage-dependent Ca(2+)-channels were found, suggesting

  13. Assessing the manipulative potentials of monkeys, apes and humans from hand proportions: implications for hand evolution.

    Science.gov (United States)

    Liu, Ming-Jin; Xiong, Cai-Hua; Hu, Di

    2016-11-30

    The hand structure possesses a greater potential for performing manipulative skills than is typically observed, whether in humans or non-human anthropoids. However, a precise assessment of the potential manipulative skills of hands has been challenging, which hampers our understanding of the evolution of manipulative abilities in anthropoid hands. Here, we establish a functional model to quantitatively infer the manipulative potentials of anthropoid hands based on hand proportions. Our results reveal a large disparity of manipulative potentials among anthropoid hands. From the aspect of hand proportions, the human hand has the best manipulative potential among anthropoids. However, the species with a manipulative potential closer to that of humans are not our nearest relatives, chimpanzees, but rather, are certain monkey species. In combination with the phylogenetically informed morphometric analyses, our results suggest that the morphological changes of non-human anthropoid hands did not coevolve with the brain to facilitate the manipulative ability during the evolutionary process, although the manipulative ability is a survival skill. The changes in non-human anthropoid hands may have more likely evolved under selective pressure for locomotion than manipulation. © 2016 The Author(s).

  14. Spermatozoa with high mitochondrial membrane potential and low tyrosine phosphorylation preferentially bind to oviduct explants in the water buffalo (Bubalus bubalis).

    Science.gov (United States)

    Saraf, Kaustubh Kishor; Kumaresan, Arumugam; Chhillar, Shivani; Nayak, Samiksha; Lathika, Sreela; Datta, Tirtha Kumar; Gahlot, Subhash Chand; Karan, Prabha; Verma, Kiran; Mohanty, Tushar Kumar

    2017-05-01

    Although it is understood that spermatozoa are subjected to selection processes to form a functional sperm reservoir in the oviduct, the mechanism remains obscure. With the aim to understand the sperm selection process in the oviduct, in the present in vitro study, we analyzed mitochondrial membrane potential and tyrosine phosphorylation status in oviduct-explants bound and unbound spermatozoa. Frozen semen from Murrah buffalo bulls (n=10) used under progeny testing programme were utilized for the study. Oviduct explants were prepared by overnight culture of epithelial cells in TCM- 199 and washed spermatozoa were added to the oviduct explants and incubated for 4h. Mitochondrial membrane potential (MMP) and tyrosine phosphorylation status of bound and unbound spermatozoa were assessed at 1h and 4h of incubation. The proportion of spermatozoa with high MMP was significantly higher (Pspermatozoa (range 84.67-96.56%) compared to unbound (range 8.70-21.03%) spermatozoa. The proportion of tyrosine phosphorylated spermatozoa was significantly higher (Pspermatozoa displaying tyrosine phosphorylation at acrosomal area was significantly (Pspermatozoa with high MMP and low tyrosine phosphorylation were preferred for oviduct-explants binding in the buffalo. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. An educational path for the magnetic vector potential and its physical implications

    International Nuclear Information System (INIS)

    Barbieri, S; Cavinato, M; Giliberti, M

    2013-01-01

    We present an educational path for the magnetic vector potential A aimed at undergraduate students and pre-service physics teachers. Starting from the generalized Ampère–Laplace law, in the framework of a slowly varying time-dependent field approximation, the magnetic vector potential is written in terms of its empirical references, i.e. the conduction currents. Therefore, once the currents are known, our approach allows for a clear and univocal physical determination of A, overcoming the mathematical indeterminacy due to the gauge transformations. We have no need to fix a gauge, since for slowly varying time-dependent electric and magnetic fields, the ‘natural’ gauge for A is the Coulomb one. We stress the difference between our approach and those usually presented in the literature. Finally, a physical interpretation of the magnetic vector potential is discussed and some examples of the calculation of A are analysed. (paper)

  16. What Can We Learn about Cholesterol's Transmembrane Distribution Based on Cholesterol-Induced Changes in Membrane Dipole Potential?

    DEFF Research Database (Denmark)

    Falkovich, Stanislav G.; Martinez-Seara, Hector; Nesterenko, Alexey M.

    2016-01-01

    on the cytosolic side, and vice versa. Biologically this implies that by altering the dipole potential, cholesterol can provide a driving force for cholesterol molecules to favor the cytosolic leaflet, in order to compensate for the intramembrane field that arises from the resting potential....

  17. The role of glial cells in Alzheimer disease: potential therapeutic implications.

    Science.gov (United States)

    Lopategui Cabezas, I; Herrera Batista, A; Pentón Rol, G

    2014-06-01

    Alzheimer (AD) disease is a complex neurodegenerative disease characterised by inflammation, neurotoxicity, oxidative stress, and reactive gliosis. Microglia and astrocytes not only act as antigen-presenting cells, but also function as effector cells releasing pro-inflammatory molecules that promote excitotoxicity and neurodegeneration. In the present review we discuss the role of glia, specifically microglia and astrocytes, in the pathophysiology of AD and possible therapeutic implications. The growing body of evidence suggesting that microglia and astrocytes play a pathogenic role and activate inflammation pathways, the neurotoxic factors released by these cells when activated, and the way these factors may disrupt the homeostasis of the central nervous system all support the hypothesis that glia-induced inflammation exacerbates AD. Inhibiting inflammation by deactivating glial cells may reduce the production of factors which contribute to neurotoxicity, and therefore result in clinical improvement. Microglia and astrocytes are therapeutic targets for the development of new drugs to combat this disease. Therapeutic strategies designed to counter the detrimental effects of overactivation of these cell populations should be investigated. Copyright © 2012 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  18. Hydroxymethylation and its potential implication in DNA repair system: A review and future perspectives.

    Science.gov (United States)

    Shukla, Ankita; Sehgal, Manika; Singh, Tiratha Raj

    2015-06-15

    The 5-hydroxymethylcytosine (5-hmC) is known to exist as a predictive indicator for a variety of cancers, neurological abnormalities and other perilous diseases. The precursor of 5-hmC i.e. 5-methylcytosine (5mC) has already gained attention as an important epigenetic regulator whereas 5-hmC remains less explored. The two modified DNA bases (5mC and 5-hmC) have absolute diverse distribution, i.e. 5-hmC is mostly restrained to the 5' end of DNA with levels directing the gene transcription whereas 5mC is mainly located at the intra- or intergenic regions of DNA repeats and within certain gene bodies. It has been reported that levels of 5-hmC in different tissues provide a useful tool for detecting numerous associated diseases and their progression. Therefore, to unravel the role of hydroxymethylation in various resulting diseases in humans, comprehensive information on this crucial process has been explored and compiled for its implication in DNA repair system. The role of miRNAs in cancer through hypo- and hypermethylation has also been explored and discussed. In this review, a broad and exclusive insight into hydroxymethylation and its association with repair mechanisms is extensively presented and it is estimated that the accessible information will be of utmost use to the biological community working in the relevant research area. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Climate change and crop natural defenses: potential implications for food security and food safety

    Science.gov (United States)

    Wheat and corn are an essential part of the world’s grain supply, but climate change has the potential to increase grain susceptibility to toxin producing fungal pathogens. While rising atmospheric [CO2] is a driving force of climate change, our understanding of how elevated [CO2] will effect grain ...

  20. Selecting for Creativity and Innovation Potential: Implications for Practice in Healthcare Education

    Science.gov (United States)

    Patterson, Fiona; Zibarras, Lara Dawn

    2017-01-01

    The ability to innovate is an important requirement in many organisations. Despite this pressing need, few selection systems in healthcare focus on identifying the potential for creativity and innovation and so this area has been vastly under-researched. As a first step towards understanding how we might select for creativity and innovation, this…

  1. Energy conservation potential in China’s petroleum refining industry: Evidence and policy implications

    International Nuclear Information System (INIS)

    Lin, Boqiang; Xie, Xuan

    2015-01-01

    Highlights: • A long-term equilibrium relationship of energy demand in China’s petroleum refining industry is established. • The sectoral energy conservation potential is evaluated by using scenarios analysis. • Energy prices, enterprise scale, R and D investment and ownership structure affect electricity intensity. • Future policy for energy conservation in China’s petroleum refining industry is suggested. - Abstract: China is currently the second largest petroleum refining country in the world due to rapid growth in recent years. Because the petroleum refining industry is energy-intensive, the rapid growth in petroleum refining and development caused massive energy consumption. China’s urbanization process will guarantee sustained growth of the industry for a long time. Therefore, it is necessary to study the energy conservation potential of the petroleum industry. This paper estimates the energy conservation potential of the industry by applying a cointegration model to investigate the long-run equilibrium relationship between energy consumption and some factors such as energy price, enterprise scale, R and D investment and ownership structure. The results show that R and D investment has the greatest reduction impact on energy intensity, and the growth of market participants (i.e. the decline of the share of state-owned companies) can improve energy efficiency of this industry. Under the advanced energy-saving scenario, the accumulated energy conservation potential will reach 230.18 million tons of coal equivalent (tce). Finally, we provide some targeted policy recommendations for industrial energy conservation

  2. Harvest residue removal and soil compaction impact forest productivity and recovery: Potential implications for bioenergy harvests

    Science.gov (United States)

    Miranda T. Curzon; Anthony W. D' Amato; Brian J. Palik

    2014-01-01

    Understanding the effects of management on forest structure and function is increasingly important in light of projected increases in both natural and anthropogenic disturbance severity and frequency with global environmental change. We examined potential impacts of the procurement of forest-derived bioenergy, a change in land use that has been suggested as a climate...

  3. Separation of Electric Fields Into Potential and Inductive Parts, and Implications for Radial Diffusion

    Science.gov (United States)

    Chan, A. A.; Ilie, R.; Elkington, S. R.; Albert, J.; Huie, W.

    2017-12-01

    It has been traditional to separate radiation belt radial-diffusion coefficients into two contributions: an "electrostatic" diffusion coefficient, which is assumed to be due to a potential (non-inductive) electric field, and an "electromagnetic" diffusion coefficient , which is assumed to be due to the combined effect of an inductive electric field and the corresponding time-dependent magnetic field. One difficulty in implementing this separation when using magnetospheric fields obtained from measurements, or from MHD simulations, is that only the total electric field is given; the separation of the electric field into potential and inductive parts is not readily available. In this work we separate the electric field using a numerical method based on the Helmholtz decomposition of the total motional electric field calculated by the BATS-R-US MHD code. The inner boundary for the electric potential is based on the Ridley Ionospheric Model solution and we assume floating boundary conditions in the solar wind. Using different idealized solar wind drivers, including a solar wind density that is oscillating at a single frequency or with a broad spectrum of frequencies, we calculate potential and inductive electric fields, electric and magnetic power spectral densities, and corresponding radial diffusion coefficients. Simulations driven by idealized solar wind conditions show a clear separation of the potential and inductive contributions to the power spectral densities and diffusion coefficients. Simulations with more realistic solar wind drivers are underway to better assess the use of electrostatic and electromagnetic diffusion coefficients in understanding ULF wave-particle interactions in Earth's radiation belts.

  4. Sustainable organic loading rate and energy recovery potential of mesophilic anaerobic membrane bioreactor for municipal wastewater treatment

    KAUST Repository

    Wei, Chunhai

    2014-08-01

    The overall performance of a mesophilic anaerobic membrane bioreactor (AnMBR) for synthetic municipal wastewater treatment was investigated under a range of organic loading rate (OLR). A very steady and high chemical oxygen demand (COD) removal (around 98%) was achieved over a broad range of volumetric OLR of 0.8-10gCOD/L/d. The sustainable volumetric and sludge OLR satisfying a permeate COD below 50mg/L for general reuse was 6gCOD/L/d and 0.63gCOD/gMLVSS (mixed liquor volatile suspended solids)/d, respectively. At a high sludge OLR of over 0.6gCOD/gMLVSS/d, the AnMBR achieved high methane production of over 300ml/gCOD (even approaching the theoretical value of 382ml/gCOD). A low biomass production of 0.015-0.026gMLVSS/gCOD and a sustainable flux of 6L/m2/h were observed. The integration of a heat pump and forward osmosis into the mesophilic AnMBR process would be a promising way for net energy recovery from typical municipal wastewater in a temperate area. © 2014 Elsevier Ltd.

  5. Plasma cadmium and zinc and their interrelationship in adult Nigerians: potential health implications

    Directory of Open Access Journals (Sweden)

    Ugwuja Emmanuel Ike

    2015-06-01

    Full Text Available Zinc (an essential trace element and cadmium (a ubiquitous environmental pollutant with acclaimed toxicity have been found to occur together in nature, with reported antagonism between the two elements. The present study aimed at determination of plasma levels of zinc (Zn and cadmium (Cd and their interrelationship in adult Nigerians. The series comprised adults (n=443 aged ≥18 yrs (mean ± SD 38.4±13.7 yrs, consisting of 117 males, 184 non-pregnant and 140 pregnant females. Sociodemographic data were collected by questionnaire while anthropometrics were determined using standard methods. Plasma Cd and Zn were determined by using an atomic absorption spectrophotometer. The mean plasma zinc and cadmium were 94.7±18.1 μg/dl and 0.150±0.548 μg/dl, respectively. Age, sex, pregnancy, and parity had no effect on either plasma Zn or Cd. Although educational level had no effect on plasma Zn, it had a significant effect on Cd; subjects possessing either secondary or tertiary education had significantly lower plasma Cd than subjects without formal education. Moreover, there seemed to be an inverse relationship between Cd and Zn, but this was not statistically significant (r=–0.089; p=0.061. Although plasma Zn was not related to BMI (r=0.037; p=0.432, Cd was significantly negatively correlated with BMI (r=–0.124; p=0.009. It may be concluded that adult Nigerians in Ebonyi State have elevated plasma levels of Cd, with apparent impact on the levels of plasma Zn. This has important public health implications considering the essential roles of Zn in the protection of Cd mediated adverse health effects. While food diversification is recommended to improve plasma Zn, efforts should be made to reduce exposure to Cd to mitigate partially its possible adverse effects.

  6. Endothelial cell-derived microparticles induce plasmacytoid dendritic cell maturation: potential implications in inflammatory diseases.

    Science.gov (United States)

    Angelot, Fanny; Seillès, Estelle; Biichlé, Sabeha; Berda, Yael; Gaugler, Béatrice; Plumas, Joel; Chaperot, Laurence; Dignat-George, Françoise; Tiberghien, Pierre; Saas, Philippe; Garnache-Ottou, Francine

    2009-11-01

    Increased circulating endothelial microparticles, resulting from vascular endothelium dysfunction, and plasmacytoid dendritic cell activation are both encountered in common inflammatory disorders. The aim of our study was to determine whether interactions between endothelial microparticles and plasmacytoid dendritic cells could contribute to such pathologies. Microparticles generated from endothelial cell lines, platelets or activated T cells were incubated with human plasmacytoid dendritic cells sorted from healthy donor blood or with monocyte-derived dendritic cells. Dendritic cell maturation was evaluated by flow cytometry, cytokine secretion as well as naive T-cell activation and polarization. Labeled microparticles were also used to study cellular interactions. Endothelial microparticles induced plasmacytoid dendritic cell maturation. In contrast, conventional dendritic cells were resistant to endothelial microparticle-induced maturation. In addition to upregulation of co-stimulatory molecules, endothelial microparticle-matured plasmacytoid dendritic cells secreted inflammatory cytokines (interleukins 6 and 8, but no interferon-alpha) and also induced allogeneic naive CD4(+) T cells to proliferate and to produce type 1 cytokines such as interferon-gamma and tumor necrosis factor-alpha. Endothelial microparticle endocytosis by plasmacytoid dendritic cells appeared to be required for plasmacytoid dendritic cell maturation. Importantly, the ability of endothelial microparticles to induce plasmacytoid dendritic cells to mature was specific as microparticles derived from activated T cells or platelets (the major source of circulating microparticules in healthy subjects) did not induce such plasmacytoid dendritic cell maturation. Our data show that endothelial microparticles specifically induce plasmacytoid dendritic cell maturation and production of inflammatory cytokines. This novel activation pathway may be implicated in various inflammatory disorders and

  7. Twitch potentiation induced by two different modalities of neuromuscular electrical stimulation: implications for motor unit recruitment.

    Science.gov (United States)

    Regina Dias Da Silva, Sarah; Neyroud, Daria; Maffiuletti, Nicola A; Gondin, Julien; Place, Nicolas

    2015-03-01

    We tested the hypothesis that twitch potentiation would be greater following conventional (CONV) neuromuscular electrical stimulation (50-µs pulse width and 25-Hz frequency) compared with wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (1-ms, 100-Hz) and voluntary (VOL) contractions, because of specificities in motor unit recruitment (random in CONV vs. random and orderly in WPHF vs. orderly in VOL). A single twitch was evoked by means of tibial nerve stimulation before and 2 s after CONV, WPHF, and VOL conditioning contractions of the plantar flexors (intensity: 10% maximal voluntary contraction; duration: 10 s) in 13 young healthy subjects. Peak twitch increased (Ptwitch potentiation results. © 2014 Wiley Periodicals, Inc.

  8. Bile acids modulate signaling by functional perturbation of plasma membrane domains.

    Science.gov (United States)

    Zhou, Yong; Maxwell, Kelsey N; Sezgin, Erdinc; Lu, Maryia; Liang, Hong; Hancock, John F; Dial, Elizabeth J; Lichtenberger, Lenard M; Levental, Ilya

    2013-12-13

    Eukaryotic cell membranes are organized into functional lipid and protein domains, the most widely studied being membrane rafts. Although rafts have been associated with numerous plasma membrane functions, the mechanisms by which these domains themselves are regulated remain undefined. Bile acids (BAs), whose primary function is the solubilization of dietary lipids for digestion and absorption, can affect cells by interacting directly with membranes. To investigate whether these interactions affected domain organization in biological membranes, we assayed the effects of BAs on biomimetic synthetic liposomes, isolated plasma membranes, and live cells. At cytotoxic concentrations, BAs dissolved synthetic and cell-derived membranes and disrupted live cell plasma membranes, implicating plasma membrane damage as the mechanism for BA cellular toxicity. At subtoxic concentrations, BAs dramatically stabilized domain separation in Giant Plasma Membrane Vesicles without affecting protein partitioning between coexisting domains. Domain stabilization was the result of BA binding to and disordering the nonraft domain, thus promoting separation by enhancing domain immiscibility. Consistent with the physical changes observed in synthetic and isolated biological membranes, BAs reorganized intact cell membranes, as evaluated by the spatial distribution of membrane-anchored Ras isoforms. Nanoclustering of K-Ras, related to nonraft membrane domains, was enhanced in intact plasma membranes, whereas the organization of H-Ras was unaffected. BA-induced changes in Ras lateral segregation potentiated EGF-induced signaling through MAPK, confirming the ability of BAs to influence cell signal transduction by altering the physical properties of the plasma membrane. These observations suggest general, membrane-mediated mechanisms by which biological amphiphiles can produce their cellular effects.

  9. Biology and potential clinical implications of tissue inhibitor of metalloproteinases-1 in colorectal cancer treatment

    DEFF Research Database (Denmark)

    Sørensen, Nanna Møller; Sørensen, irene Vejgaard; Würtz, Sidse Ørnbjerg

    2008-01-01

    Colorectal cancer (CRC) is the second leading cause of cancer-related death in the industrialized world. About half of "curatively" resected patients develop recurrent disease within the next 3-5 years despite the lack of clinical, histological and biochemical evidence of remaining overt disease ...... knowledge of the biology of TIMP-1 as well as the potential use of TIMP-1 as a biological marker in the management of CRC patients....

  10. Affective Aspects of Perceived Loss of Control and Potential Implications for Brain-Computer Interfaces

    Directory of Open Access Journals (Sweden)

    Sebastian Grissmann

    2017-07-01

    Full Text Available Most brain-computer interfaces (BCIs focus on detecting single aspects of user states (e.g., motor imagery in the electroencephalogram (EEG in order to use these aspects as control input for external systems. This communication can be effective, but unaccounted mental processes can interfere with signals used for classification and thereby introduce changes in the signal properties which could potentially impede BCI classification performance. To improve BCI performance, we propose deploying an approach that potentially allows to describe different mental states that could influence BCI performance. To test this approach, we analyzed neural signatures of potential affective states in data collected in a paradigm where the complex user state of perceived loss of control (LOC was induced. In this article, source localization methods were used to identify brain dynamics with source located outside but affecting the signal of interest originating from the primary motor areas, pointing to interfering processes in the brain during natural human-machine interaction. In particular, we found affective correlates which were related to perceived LOC. We conclude that additional context information about the ongoing user state might help to improve the applicability of BCIs to real-world scenarios.

  11. Epigenetic and antioxidant effects of dietary isothiocyanates and selenium: potential implications for cancer chemoprevention.

    Science.gov (United States)

    Barrera, Lawrence N; Cassidy, Aedin; Johnson, Ian T; Bao, Yongping; Belshaw, Nigel J

    2012-05-01

    There is evidence from epidemiological studies suggesting that increased consumption of cruciferous vegetables may protect against specific cancers more effectively than total fruit and vegetable intake. These beneficial effects are attributed to the glucosinolate breakdown products, isothiocyanates (ITC). Similarly, selenium (Se) consumption has also been inversely associated with cancer risk and as an integral part of many selenoproteins may influence multiple pathways in the development of cancer. This paper will briefly review the current state of knowledge concerning the effect of Se and ITC in cancer development with a particular emphasis on its antioxidant properties, and will also address whether alterations in DNA methylation may be a potential mechanism whereby these dietary constituents protect against the carcinogenic process. Furthermore, we will discuss the advantages of combining ITC and Se to benefit from their complementary mechanisms of action to potentially protect against the alterations leading to neoplasia. Based on this review it may be concluded that an understanding of the impact of ITC and Se on aberrant DNA methylation in relation to factors modulating gene-specific and global methylation patterns, in addition to the effect of these food constituents as modulators of key selenoenzymes, such as gastrointestinal glutathione peroxidase-2 (GPx2) and thioredoxin reductase-1 (TrxR1), may provide insights into the potential synergy among various components of a plant-based diet that may counteract the genetic and epigenetic alterations that initiate and sustain neoplasia.

  12. Micro-RNAs as Potential Predictors of Response to Breast Cancer Systemic Therapy: Future Clinical Implications

    Science.gov (United States)

    Campos-Parra, Alma D.; Cuamani Mitznahuatl, Gerardo; Pedroza-Torres, Abraham; Vázquez Romo, Rafael; Porras Reyes, Fany Iris; López-Urrutia, Eduardo; Pérez-Plasencia, Carlos

    2017-01-01

    Despite advances in diagnosis and new treatments such as targeted therapies, breast cancer (BC) is still the most prevalent tumor in women worldwide and the leading cause of death. The principal obstacle for successful BC treatment is the acquired or de novo resistance of the tumors to the systemic therapy (chemotherapy, endocrine, and targeted therapies) that patients receive. In the era of personalized treatment, several studies have focused on the search for biomarkers capable of predicting the response to this therapy; microRNAs (miRNAs) stand out among these markers due to their broad spectrum or potential clinical applications. miRNAs are conserved small non-coding RNAs that act as negative regulators of gene expression playing an important role in several cellular processes, such as cell proliferation, autophagy, genomic stability, and apoptosis. We reviewed recent data that describe the role of miRNAs as potential predictors of response to systemic treatments in BC. Furthermore, upon analyzing the collected published information, we noticed that the overexpression of miR-155, miR-222, miR-125b, and miR-21 predicts the resistance to the most common systemic treatments; nonetheless, the function of these particular miRNAs must be carefully studied and further analyses are still necessary to increase knowledge about their role and future potential clinical uses in BC. PMID:28574440

  13. Nanotechnology and glaucoma: a review of the potential implications of glaucoma nanomedicine.

    Science.gov (United States)

    Kim, Nathaniel J; Harris, Alon; Gerber, Austin; Tobe, Leslie Abrams; Amireskandari, Annahita; Huck, Andrew; Siesky, Brent

    2014-04-01

    The purpose of this review is to discuss the evolution of nanotechnology and its potential diagnostic and therapeutic applications in the field of ophthalmology, particularly as it pertains to glaucoma. We reviewed literature using MEDLINE and PubMed databases with the following search terms: glaucoma, nanotechnology, nanomedicine, nanoparticles, ophthalmology and liposomes. We also reviewed pertinent references from articles found in this search. A brief history of nanotechnology and nanomedicine will be covered, followed by a discussion of the advantages and concerns of using this technology in the field of glaucoma. We will look at various studies concerning the development of nanomedicine, its potential applications in ocular drug delivery, diagnostic and imaging modalities and, surgical techniques. In particular, the challenges of assuring safety and efficacy of nanomedicine will be examined. We conclude that nanotechnology offers a novel approach to expanding diagnostic, imaging and surgical modalities in glaucoma and may contribute to the knowledge of disease pathogenesis at a molecular level. However, more research is needed to better elucidate the mechanism of cellular entry, the potential for nanoparticle cytotoxicity and the assurance of clinical efficacy.

  14. Revealing mechanisms of selective, concentration-dependent potentials of 4-hydroxy-2-nonenal to induce apoptosis in cancer cells through inactivation of membrane-associated catalase.

    Science.gov (United States)

    Bauer, Georg; Zarkovic, Neven

    2015-04-01

    Tumor cells generate extracellular superoxide anions and are protected against superoxide anion-mediated intercellular apoptosis-inducing signaling by the expression of membrane-associated catalase. 4-Hydroxy-2-nonenal (4-HNE), a versatile second messenger generated during lipid peroxidation, has been shown to induce apoptosis selectively in malignant cells. The findings described in this paper reveal the strong, concentration-dependent potential of 4-HNE to specifically inactivate extracellular catalase of tumor cells both indirectly and directly and to consequently trigger apoptosis in malignant cells through superoxide anion-mediated intercellular apoptosis-inducing signaling. Namely, 4-HNE caused apoptosis selectively in NOX1-expressing tumor cells through inactivation of their membrane-associated catalase, thus reactivating subsequent intercellular signaling through the NO/peroxynitrite and HOCl pathways, followed by the mitochondrial pathway of apoptosis. Concentrations of 4-HNE of 1.2 µM and higher directly inactivated membrane-associated catalase of tumor cells, whereas at lower concentrations, 4-HNE triggered a complex amplificatory pathway based on initial singlet oxygen formation through H2O2 and peroxynitrite interaction. Singlet-oxygen-dependent activation of the FAS receptor and caspase-8 increased superoxide anion generation by NOX1 and amplification of singlet oxygen generation, which allowed singlet-oxygen-dependent inactivation of catalase. 4-HNE and singlet oxygen cooperate in complex autoamplificatory loops during this process. The finding of these novel anticancer pathways may be useful for understanding the role of 4-HNE in the control of malignant cells and for the optimization of ROS-dependent therapeutic approaches including antioxidant treatments. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Mixed-matrix membranes with enhanced antifouling activity: probing the surface-tailoring potential of Tiron and chromotropic acid for nano-TiO2.

    Science.gov (United States)

    Pal, Avishek; Dey, T K; Debnath, A K; Bhushan, Bharat; Sahu, A K; Bindal, R C; Kar, Soumitra

    2017-09-01

    Mixed-matrix membranes (MMMs) were developed by impregnating organofunctionalized nanoadditives within fouling-susceptible polysulfone matrix following the non-solvent induced phase separation (NIPS) method. The facile functionalization of nanoparticles of anatase TiO 2 (nano-TiO 2 ) by using two different organoligands, viz . Tiron and chromotropic acid, was carried out to obtain organofunctionalized nanoadditives, F T -nano-TiO 2 and F C -nano-TiO 2 , respectively. The structural features of nanoadditives were evaluated by X-ray diffraction, X-ray photoelectron spectroscopy, Raman and Fourier transform infrared spectroscopy, which established that Tiron leads to the blending of chelating and bridging bidentate geometries for F T -nano-TiO 2 , whereas chromotropic acid produces bridging bidentate as well as monodentate geometries for F C -nano-TiO 2 . The surface chemistry of the studied membranes, polysulfone (Psf): F T -nano-TiO 2 UF and Psf: F C -nano-TiO 2 UF, was profoundly influenced by the benign distributions of the nanoadditives enriched with distinctly charged sites ([Formula: see text]), as evidenced by superior morphology, improved topography, enhanced surface hydrophilicity and altered electrokinetic features. The membranes exhibited enhanced solvent throughputs, viz . 3500-4000 and 3400-4300 LMD at 1 bar of transmembrane pressure, without significant compromise in their rejection attributes. The flux recovery ratios and fouling resistive behaviours of MMMs towards bovine serum albumin indicated that the nanoadditives could impart stable and appreciable antifouling activity, potentially aiding in a sustainable ultrafiltration performance.

  16. Underground autocatalytic-criticality potential and its implications to weapons fissile- material disposition

    International Nuclear Information System (INIS)

    Choi, J.-S.

    1998-01-01

    Several options for weapons fissile-material disposition, such as once-through mixed- oxide (MOX) fuel in reactors or immobilisation in waste glass, would result in end products requiring geologic disposal. The criticality potential of the fissile end products containing U-235 and Pu-239 and the associated consequences in a geologic setting are important considerations for the final disposal of these materials. The possibility of underground criticality, and especially autocatalytic criticality, is affected by (1) groundwater leaking into a failed waste container, (2) preferential leaching of neutron absorbers or of fissile material from a failed container, and (3) preferential deposition of fissile material in the surrounding rock. Bowman and Venneri have pointed out that fissile material mixed with varying compositions of water and silica can undergo a nuclear chain reaction. Some configurations can become autocatalytically supercritical resulting in considerable energy release, terminated finally by disassembly. Some reviews rejected the Bowman and Venneri warning as implausible because of low probabilities of scenarios that could lead to such configurations. Sanchez et al. reported possible supercritical conditions in systems of Pu-SiO 2 -H 2 O and Pu-tuff-H 2 O but concluded that the probability of forming such combinations is extremely low. Kastenberg et al. studied the potential for autocatalytic criticality of plutonium or highly enriched uranium in the proposed Yucca Mountain geologic repository. They concluded that plutonium or uranium could, theoretically, become supercritical, but that such criticality is unlikely given the hydrology, geology and geochemistry of the Yucca Mountain site. These studies are not definitive. The possibility of criticality exists. Detailed mechanisms have not been sufficiently studied for clear conclusions on the probabilities of occurrence. More technical analysis is needed to understand the potential for underground

  17. Modeling transcranial magnetic stimulation from the induced electric fields to the membrane potentials along tractography-based white matter fiber tracts

    Science.gov (United States)

    De Geeter, Nele; Dupré, Luc; Crevecoeur, Guillaume

    2016-04-01

    Objective. Transcranial magnetic stimulation (TMS) is a promising non-invasive tool for modulating the brain activity. Despite the widespread therapeutic and diagnostic use of TMS in neurology and psychiatry, its observed response remains hard to predict, limiting its further development and applications. Although the stimulation intensity is always maximum at the cortical surface near the coil, experiments reveal that TMS can affect deeper brain regions as well. Approach. The explanation of this spread might be found in the white matter fiber tracts, connecting cortical and subcortical structures. When applying an electric field on neurons, their membrane potential is altered. If this change is significant, more likely near the TMS coil, action potentials might be initiated and propagated along the fiber tracts towards deeper regions. In order to understand and apply TMS more effectively, it is important to capture and account for this interaction as accurately as possible. Therefore, we compute, next to the induced electric fields in the brain, the spatial distribution of the membrane potentials along the fiber tracts and its temporal dynamics. Main results. This paper introduces a computational TMS model in which electromagnetism and neurophysiology are combined. Realistic geometry and tissue anisotropy are included using magnetic resonance imaging and targeted white matter fiber tracts are traced using tractography based on diffusion tensor imaging. The position and orientation of the coil can directly be retrieved from the neuronavigation system. Incorporating these features warrants both patient- and case-specific results. Significance. The presented model gives insight in the activity propagation through the brain and can therefore explain the observed clinical responses to TMS and their inter- and/or intra-subject variability. We aspire to advance towards an accurate, flexible and personalized TMS model that helps to understand stimulation in the connected

  18. The Balanced Budget Act: potential implications for the practice of vascular surgery.

    Science.gov (United States)

    Roddy, S P; O'Donnell, T F; Wilson, A L; Estes, J M; Mackey, W C

    2000-02-01

    and to compensate for the fixed expenses of academic medicine. The Balanced Budget Act raises an equity concern for AMCs because it differentially affects the centers with the best outcomes. The financial implication of this may be a direct incentive for procedures to be done in centers with less optimal outcomes.

  19. Health risk implications of potentially toxic metals in street dust and surface soil of Tehran, Iran.

    Science.gov (United States)

    Dehghani, Sharareh; Moore, Farid; Keshavarzi, Behnam; Hale, Beverley A

    2017-02-01

    In this study a total of 30 street dusts and 10 surface soils were collected in the central district of Tehran and analyzed for major potentially toxic metals. Street dust was found to be greatly enriched in Sb, Pb, Cu and Zn and moderately enriched in Cr, Mn, Mo and Ni. Contamination of Cu, Sb, Pb and Zn was clearly related to anthropogenic sources such as brake wear, tire dust, road abrasion and fossil fuel combustion. Spatial distribution of pollution load index in street dust suggested that industries located south-west of the city intensify street dust pollution. Microscopic studies revealed six dominant group of morphological structures in calculation of the exposurethe street dusts and surface soils, with respect to different geogenic and anthropogenic sources. The BCR (the European Community Bureau of Reference) sequential extraction results showed that Sb, Ni, Mo, As and Cr bonded to silicates and sulfide minerals were highly resistant to dissolution. In contrast, Zn, Cd, and Mn were mostly associated with the exchangeable phase and thus would be easily mobilized in the environment. Cu was the most abundant metal in the reducible fraction, indicating its adsorption to iron and manganese oxy-hydroxides. Pb was equally extracted from exchangeable and reducible fractions. Anthropogenic sources related to traffic apparently play a small role in Cr, Ni and Mo contamination and dispersed them as bioavailable forms but with reduced mobility and bioavailablity due to high potential of complexation and adsorption to organic matter and iron and manganese oxy-hydroxides. Calculated Hazard Index (HI) suggests ingestion as the most important pathway for the majority of PTMs in children and dermal contact as the main exposure route for Cr, Cd and Sb for adults. The HIs and fractionation pattern of elements revealed Pb as the sole element that bears potential health risk in street dust and surface soil. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Regulation of gap junction conductance by calcineurin through Cx43 phosphorylation: implications for action potential conduction.

    Science.gov (United States)

    Jabr, Rita I; Hatch, Fiona S; Salvage, Samantha C; Orlowski, Alejandro; Lampe, Paul D; Fry, Christopher H

    2016-11-01

    Cardiac arrhythmias are associated with raised intracellular [Ca 2+ ] and slowed action potential conduction caused by reduced gap junction (GJ) electrical conductance (Gj). Ventricular GJs are composed of connexin proteins (Cx43), with Gj determined by Cx43 phosphorylation status. Connexin phosphorylation is an interplay between protein kinases and phosphatases but the precise pathways are unknown. We aimed to identify key Ca 2+ -dependent phosphorylation sites on Cx43 that regulate cardiac gap junction conductance and action potential conduction velocity. We investigated the role of the Ca 2+ -dependent phosphatase, calcineurin. Intracellular [Ca 2+ ] was raised in guinea-pig myocardium by a low-Na solution or increased stimulation. Conduction velocity and Gj were measured in multicellular strips. Phosphorylation of Cx43 serine residues (S365 and S368) and of the intermediary regulator I1 at threonine35 was measured by Western blot. Measurements were made in the presence and absence of inhibitors to calcineurin, I1 or protein phosphatase-1 and phosphatase-2.Raised [Ca 2 + ] i decreased Gj, reduced Cx43 phosphorylation at S365 and increased it at S368; these changes were reversed by calcineurin inhibitors. Cx43-S368 phosphorylation was reversed by the protein kinase C inhibitor chelerythrine. Raised [Ca 2+ ] i also decreased I1 phosphorylation, also prevented by calcineurin inhibitors, to increase activity of the Ca 2+ -independent phosphatase, PPI. The PP1 inhibitor, tautomycin, prevented Cx43-365 dephosphorylation, Cx43-S368 phosphorylation and Gj reduction in raised [Ca 2+ ] i . PP2A had no role. Conduction velocity was reduced by raised [Ca 2+ ] i and reversed by calcineurin inhibitors. Reduced action potential conduction and Gj in raised [Ca 2+ ] are regulated by calcineurin-dependent Cx43-S365 phosphorylation, leading to Cx43-S368 dephosphorylation. The calcineurin action is indirect, via I1 dephosphorylation and subsequent activation of PP1.

  1. Adaptive genetic potential of coniferous forest tree species under climate change: implications for sustainable forest management

    Science.gov (United States)

    Mihai, Georgeta; Birsan, Marius-Victor; Teodosiu, Maria; Dumitrescu, Alexandru; Daia, Mihai; Mirancea, Ionel; Ivanov, Paula; Alin, Alexandru

    2017-04-01

    Mountain ecosystems are extremely vulnerable to climate change. The real potential for adaptation depends upon the existence of a wide genetic diversity in trees populations, upon the adaptive genetic variation, respectively. Genetic diversity offers the guarantee that forest species can survive, adapt and evolve under the influence of changing environmental conditions. The aim of this study is to evaluate the genetic diversity and adaptive genetic potential of two local species - Norway spruce and European silver fir - in the context of regional climate change. Based on data from a long-term provenance experiments network and climate variables spanning over more than 50 years, we have investigated the impact of climatic factors on growth performance and adaptation of tree species. Our results indicate that climatic and geographic factors significantly affect forest site productivity. Mean annual temperature and annual precipitation amount were found to be statistically significant explanatory variables. Combining the additive genetic model with the analysis of nuclear markers we obtained different images of the genetic structure of tree populations. As genetic indicators we used: gene frequencies, genetic diversity, genetic differentiation, genetic variance, plasticity. Spatial genetic analyses have allowed identifying the genetic centers holding high genetic diversity which will be valuable sources of gene able to buffer the negative effects of future climate change. Correlations between the marginal populations and in the optimal vegetation, between the level of genetic diversity and ecosystem stability, will allow the assessment of future risks arising from current genetic structure. Therefore, the strategies for sustainable forest management have to rely on the adaptive genetic variation and local adaptation of the valuable genetic resources. This work was realized within the framework of the project GENCLIM (Evaluating the adaptive potential of the main

  2. The Potential of the CNS as a Reservoir for HIV-1 Infection: Implications for HIV Eradication.

    Science.gov (United States)

    Fois, Alessandro F; Brew, Bruce J

    2015-06-01

    The ability of HIV-1 to establish latent infection is a key obstacle to its eradication despite the existence of effective antiretroviral drugs. The brain has been postulated as a reservoir for latent infection, but its role in HIV persistence remains unclear. In this review, we discuss the evidence surrounding the role of the central nervous system (CNS) as a viral reservoir and the potential challenges this might present in eradicating HIV. The strategies for eradication of HIV and their application to latent CNS infection are explored. Finally, we outline new developments in drug delivery and new therapeutic modalities designed to target HIV infection in the CNS.

  3. Potential implications of the bystander effect on TCP and EUD when considering target volume dose heterogeneity.

    Science.gov (United States)

    Balderson, Michael J; Kirkby, Charles

    2015-01-01

    In light of in vitro evidence suggesting that radiation-induced bystander effects may enhance non-local cell killing, there is potential for impact on radiotherapy treatment planning paradigms such as the goal of delivering a uniform dose throughout the clinical target volume (CTV). This work applies a bystander effect model to calculate equivalent uniform dose (EUD) and tumor control probability (TCP) for external beam prostate treatment and compares the results with a more common model where local response is dictated exclusively by local absorbed dose. The broad assumptions applied in the bystander effect model are intended to place an upper limit on the extent of the results in a clinical context. EUD and TCP of a prostate cancer target volume under conditions of increasing dose heterogeneity were calculated using two models: One incorporating bystander effects derived from previously published in vitro bystander data ( McMahon et al. 2012 , 2013a); and one using a common linear-quadratic (LQ) response that relies exclusively on local absorbed dose. Dose through the CTV was modelled as a normal distribution, where the degree of heterogeneity was then dictated by changing the standard deviation (SD). Also, a representative clinical dose distribution was examined as cold (low dose) sub-volumes were systematically introduced. The bystander model suggests a moderate degree of dose heterogeneity throughout a target volume will yield as good or better outcome compared to a uniform dose in terms of EUD and TCP. For a typical intermediate risk prostate prescription of 78 Gy over 39 fractions maxima in EUD and TCP as a function of increasing SD occurred at SD ∼ 5 Gy. The plots only dropped below the uniform dose values for SD ∼ 10 Gy, almost 13% of the prescribed dose. Small, but potentially significant differences in the outcome metrics between the models were identified in the clinically-derived dose distribution as cold sub-volumes were introduced. In terms of

  4. Proposed Nuclear Power Plants in the UK-Potential Radiological Implications for Ireland

    International Nuclear Information System (INIS)

    McMahon, C.; Kelleher, K.; McGinnity, P.; Organo, C.; Smith, K.; Currivan, L.; Ryan, T.

    2013-05-01

    The UK Government has identified up to eight locations for the construction of new nuclear power plants by 2025. Five of these locations are on the Irish Sea coast. The Radiological Protection Institute of Ireland, RPII was requested by the Minister for the Environment, Community and Local Government to undertake an assessment of the potential radiological impacts on Ireland from this New Build Programme. This report presents the findings of the potential impacts on Ireland of both the anticipated routine radioactive discharges and of a range of postulated nuclear accident scenarios. The following points are the principal findings of the report. Given the prevailing wind direction in Ireland, radioactive contamination in the air, either from routine operation of the proposed nuclear power plants or accidental releases, will most often be transported away from Ireland. The routine operation of the proposed nuclear power plants will have no measurable radiological impact on Ireland or the Irish marine environment. The severe accident scenarios assessed ranged in their estimated frequency of occurrance from 1 in 50,000 to 1 in 33 million per year. The assessment used a weather pattern that maximised the transfer of radioactivity to Ireland. For the severe accident scenarios assessed, food controls or agriculture protective measures would generally be required in Ireland to reduce exposure of the population so as to mitigate potential long-term health effects. In the accident scenario with an estimated 1 in 33 million chance of occurring, short-term measures such as staying indoors would also be advised as a precautionary measure. In general, the accidents with higher potential impact on Ireland are the ones least likely to occur. Regardless of the radiological impact, any accident at the proposed nuclear power plants leading to an increase of radioactivity levels in Ireland would have a socio-economic impact on Ireland. A major accidental release of radioactivity to

  5. Potential risks of nanotechnology to humans and environment: implications and response mechanisms in Africa

    CSIR Research Space (South Africa)

    Musee, N

    2011-11-01

    Full Text Available www.csir.co.za ENM exposure routes, uptake and potential translocation Dermal Oral Inhalation Ocular Lymphatic System Gastro- intestinal Tract Organs Circulatory System (blood) Respiratory Tract Brain Nasal Cavity Yokel et al. 2011 N... fibrosarcoma cells (left) and human skin/carcinoma cells (right). (A) unexposed cells; (B?F) 24 h after exposure to 3.12, 6.25, 12.5, 25 & 50 ?g/mL nAg respectively (magnification 200?). ? At higher concentrations cells became less polyhedral, more fusiform...

  6. Occurrence and distribution of tetraether membrane lipids in soils: implications for the use of the TEX86 proxy and the BIT index

    NARCIS (Netherlands)

    Weijers, J.W.H.; Schouten, S.; Spaargaren, O.C.; Sinnige Damsté, J.S.

    2006-01-01

    A diverse collection of globally distributed soil samples was analyzed for its glycerol dialkyl glycerol tetraether (GDGT) membrane lipid content. Branched GDGTs, derived from anaerobic soil bacteria, were the most dominant and were found in all soils. Isoprenoid GDGTs, membrane lipids of Archaea,

  7. Effect of pinacidil on norepinephrine- and potassium-induced contractions and membrane potential in rat and human resistance vessels and in rat aorta

    International Nuclear Information System (INIS)

    Videbaek, L.M.; Aalkjaer, C.; Mulvany, M.J.

    1988-01-01

    The effect of pinacidil on contractile responses to norepinephrine, potassium, and membrane potential was examined in rat and human resistance vessels. In some experiments rat aorta was also used. Pinacidil (0.1-30 microM) caused a concentration-dependent relaxation of norepinephrine-induced contractions in all vessels studied. In the same concentration range, pinacidil had only little effect on potassium (125 mM) activated rat mesenteric and femoral resistance vessels. In denervated rat mesenteric resistance vessels, a depolarization with potassium (125 mM) before superimposing a norepinephrine tone markedly diminished the effect of pinacidil. In resting rat mesenteric resistance vessels, pinacidil (1-10 microM) caused a hyperpolarization of 10-15 mV. In rat aorta, pinacidil (10 microM) caused a significant (p less than 0.001) increase in 86 Rb+ efflux rate constant whereas 1 microM had no effect. The results of these experiments indicate that the vasodilating effect may be caused by a hyperpolarization of the vascular smooth muscle cell membrane

  8. First study on gene expression of cement proteins and potential adhesion-related genes of a membranous-based barnacle as revealed from Next-Generation Sequencing technology

    KAUST Repository

    Lin, Hsiu Chin

    2013-12-12

    This is the first study applying Next-Generation Sequencing (NGS) technology to survey the kinds, expression location, and pattern of adhesion-related genes in a membranous-based barnacle. A total of 77,528,326 and 59,244,468 raw sequence reads of total RNA were generated from the prosoma and the basis of Tetraclita japonica formosana, respectively. In addition, 55,441 and 67,774 genes were further assembled and analyzed. The combined sequence data from both body parts generates a total of 79,833 genes of which 47.7% were shared. Homologues of barnacle cement proteins - CP-19K, -52K, and -100K - were found and all were dominantly expressed at the basis where the cement gland complex is located. This is the main area where transcripts of cement proteins and other potential adhesion-related genes were detected. The absence of another common barnacle cement protein, CP-20K, in the adult transcriptome suggested a possible life-stage restricted gene function and/or a different mechanism in adhesion between membranous-based and calcareous-based barnacles. © 2013 © 2013 Taylor & Francis.

  9. Vaccine Timeliness: A Cost Analysis of the Potential Implications of Delayed Pertussis Vaccination in the US.

    Science.gov (United States)

    Curran, Desmond; Terlinden, Augustin; Poirrier, Jean-Etienne; Masseria, Cristina; Krishnarajah, Girishanthy

    2016-05-01

    Pertussis infection remains an important public health problem, particularly in infants. Despite high coverage, pertussis vaccination delays can leave infants at a vulnerable age with less protection than anticipated. Current diphtheria-tetanus-pertussis (DTaP) vaccination timeliness for the first 3 doses in the US was estimated using National Immunization Survey data. A Markov model estimated the potential impact on outcomes and costs of a hypothetical situation of vaccination at exactly 60, 120 and 180 days, compared with current timeliness. Incidence and unit cost data came from published sources. Age-specific incidence (for month of life) of pertussis and the associated probabilities of hospitalization and death for the US, during 2000-2007, were taken from a recently published US DTaP vaccination cost-effectiveness study. The cost analysis was conducted from the healthcare system's perspective over a 1-year time horizon. A regression analysis was conducted to explore the factors associated with vaccination delay. Current DTaP vaccination was estimated to be delayed by 16, 27 and 44 days, for the first, second and third doses, respectively, relative to vaccination at exactly 60, 120 and 180 days. The model estimated that vaccination at exactly age 60, 120 and 180 days could prevent approximately 278 pertussis cases, 103 hospitalizations and 1 death in infants aged vaccine doses could potentially reduce subsequent pertussis cases, hospitalizations, deaths and medical costs in infants aged <1 year in the US.

  10. Genetic variability in the compatibility between Schistosoma haematobium and its potential vectors in Niger. Epidemiological implications.

    Science.gov (United States)

    Véra, C; Jourdane, J; Sellin, B; Combes, C

    1990-06-01

    A populational study of the compatibility between Schistosoma haematobium and its potential vectors has been carried out in the Niger, confronting samples of S. haematobium populations from three epidemiologic foci with Bulinus populations originating from the same focus (sympatric infection) and with Bulinus populations from other foci (allopatric infections). The three transmission foci selected were irrigation canals in ricefields along the Niger river where one finds: Bulinus truncatus rohlfsi, Bulinus globosus, Bulinus forskalii and Bulinus senegalensis; temporary pools in the Sahel area where one finds B. truncatus and B. senegalensis; permanent pools of the "guelta" type in Sahara area where only B. truncatus occurs. As a compatibility test, the snail infection test was selected, with particular emphasis on optimising its reliability. Snail-infection experiments showed that B. truncatus and B. senegalensis are very good potential vectors, with infection rates ranging between 71.5 and 85.9%. B. globosus and B. forskalii, on the other hand, are totally incompatible. The mean infection percentages in the sympatric and allopatric combinations carried out with the S. haematobium-B. truncatus couple were very similar. This character strongly suggests a lack of isolation in schistosome populations and a circulation of the parasite genome through the mobility of infected human populations (Peuls and Touaregs) in Sahel zone. This study, in relation with snail surveys carried out in parallel, shows that the main types of aquatic environments on the Niger act as high risk areas for schistosome transmission.

  11. Free trade area in southeast Europe: Growth potentials and implications for Croatia

    Directory of Open Access Journals (Sweden)

    Nela Vlahinić-Dizdarević

    2004-11-01

    Full Text Available Paper focuses on preconditions, actual trade flows and growth potentials of the Free Trade Zone in Southeast Europe. Further trade liberalisation and implementation of all 21 bilateral trade agreementswould be important incentive for intra-regional trade, especially within SEE-5, where, according to gravity model results, there exist situations of “under-trade”. Bilateral trade between Croatia and S&MNrepresents such “under-trade” situation that gives large space for Croatian export growth to this market. On the other hand, trade with B&His already above the predicted level and it could even fall in the future because great part of B&H imports was triggered by Western assistance. According to the analysis, the establishment of the Free Trade Area in SEE gives potentials for an increase in intra-regional trade (especially SEE-5, but these benefits could be fully reached only by pursuing parallel trade integration towards the EU in order to avoid trade diversion effect.

  12. Nutritional Ketosis and Mitohormesis: Potential Implications for Mitochondrial Function and Human Health

    Directory of Open Access Journals (Sweden)

    Vincent J. Miller

    2018-01-01

    Full Text Available Impaired mitochondrial function often results in excessive production of reactive oxygen species (ROS and is involved in the etiology of many chronic diseases, including cardiovascular disease, diabetes, neurodegenerative disorders, and cancer. Moderate levels of mitochondrial ROS, however, can protect against chronic disease by inducing upregulation of mitochondrial capacity and endogenous antioxidant defense. This phenomenon, referred to as mitohormesis, is induced through increased reliance on mitochondrial respiration, which can occur through diet or exercise. Nutritional ketosis is a safe and physiological metabolic state induced through a ketogenic diet low in carbohydrate and moderate in protein. Such a diet increases reliance on mitochondrial respiration and may, therefore, induce mitohormesis. Furthermore, the ketone β-hydroxybutyrate (BHB, which is elevated during nutritional ketosis to levels no greater than those resulting from fasting, acts as a signaling molecule in addition to its traditionally known role as an energy substrate. BHB signaling induces adaptations similar to mitohormesis, thereby expanding the potential benefit of nutritional ketosis beyond carbohydrate restriction. This review describes the evidence supporting enhancement of mitochondrial function and endogenous antioxidant defense in response to nutritional ketosis, as well as the potential mechanisms leading to these adaptations.

  13. Nutritional Ketosis and Mitohormesis: Potential Implications for Mitochondrial Function and Human Health

    Science.gov (United States)

    Villamena, Frederick A.

    2018-01-01

    Impaired mitochondrial function often results in excessive production of reactive oxygen species (ROS) and is involved in the etiology of many chronic diseases, including cardiovascular disease, diabetes, neurodegenerative disorders, and cancer. Moderate levels of mitochondrial ROS, however, can protect against chronic disease by inducing upregulation of mitochondrial capacity and endogenous antioxidant defense. This phenomenon, referred to as mitohormesis, is induced through increased reliance on mitochondrial respiration, which can occur through diet or exercise. Nutritional ketosis is a safe and physiological metabolic state induced through a ketogenic diet low in carbohydrate and moderate in protein. Such a diet increases reliance on mitochondrial respiration and may, therefore, induce mitohormesis. Furthermore, the ketone β-hydroxybutyrate (BHB), which is elevated during nutritional ketosis to levels no greater than those resulting from fasting, acts as a signaling molecule in addition to its traditionally known role as an energy substrate. BHB signaling induces adaptations similar to mitohormesis, thereby expanding the potential benefit of nutritional ketosis beyond carbohydrate restriction. This review describes the evidence supporting enhancement of mitochondrial function and endogenous antioxidant defense in response to nutritional ketosis, as well as the potential mechanisms leading to these adaptations. PMID:29607218

  14. Assessing global potential and implications of Carbon Dioxide Removal: how much, for how long, and where might it take us?

    Science.gov (United States)

    Scott, V.

    2014-12-01

    Aiming to keep cumulative anthropogenic carbon release within the 2 degrees C warming budget, useful energy services and value of fossil carbon might be retained if its extraction is balanced by carbon dioxide capture and carbon storage creation. Here, we examine this proposition: assessing the global resource available for carbon storage, the reliable duration of storage, and exploring the resulting hierarchy of different storage types. The balance between fossil carbon supply, and the sufficiency (size) and capability (technology, security) of candidate carbon stores is assessed. The timescale of carbon retention by the variety of proposed stores has potentially important consequences for future climates. A distinction between 'permanent' and 'temporary' carbon storage is considered, and the results and implications for the usage of 'temporary' stores discussed.

  15. A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes

    NARCIS (Netherlands)

    Arza, Vamsi Spandan; Meschini, Valentina; Ostilla-Mónico, Rodolfo; Lohse, Detlef; Querzoli, Giorgio; de Tullio, Marco D.; Verzicco, Roberto

    2017-01-01

    In this paper we show and discuss how the deformation dynamics of closed liquid–liquid interfaces (for example drops and bubbles) can be replicated with use of a phenomenological interaction potential model. This new approach to simulate liquid–liquid interfaces is based on the fundamental principle

  16. Mitochondrial membrane potential in human neutrophils is maintained by complex III activity in the absence of supercomplex organisation

    NARCIS (Netherlands)

    B.J. van Raam (Bram); W.J. Sluiter (Wim); F.R.C. de Wit (Frank); D. Roos (Dirk); A.J. Verhoeven (Arthur); T.W. Kuijpers (Taco W.)

    2008-01-01

    textabstractBackground: Neutrophils depend mainly on glycolysis for their enegry provision. Their mitochondria maintain a membrace potential (ΔΨm), which is usually generated by the repiratory chain complexes. We investigated the source of ΔΨm in neutrophils, as compared to peripheral blood

  17. Behavioral and neural responses of toads to salt solutions correlate with basolateral membrane potential of epidermal cells of the skin

    DEFF Research Database (Denmark)

    Hillyard, Stanley D; Baula, Victor; Tuttle, Wendy

    2007-01-01

    low, V(b) transiently hyperpolarized to values near the equilibrium potential for K(+) and corresponded with the reduced neural response. These results support the hypothesis that chemosensory function of the skin is analogous to that of mammalian taste cells but utilizes paracellular ion transport...

  18. A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes

    Science.gov (United States)

    Spandan, Vamsi; Meschini, Valentina; Ostilla-Mónico, Rodolfo; Lohse, Detlef; Querzoli, Giorgio; de Tullio, Marco D.; Verzicco, Roberto

    2017-11-01

    In this paper we show and discuss how the deformation dynamics of closed liquid-liquid interfaces (for example drops and bubbles) can be replicated with use of a phenomenological interaction potential model. This new approach to simulate liquid-liquid interfaces is based on the fundamental principle of minimum potential energy where the total potential energy depends on the extent of deformation of a spring network distributed on the surface of the immersed drop or bubble. Simulating liquid-liquid interfaces using this model require computing ad-hoc elastic constants which is done through a reverse-engineered approach. The results from our simulations agree very well with previous studies on the deformation of drops in standard flow configurations such as a deforming drop in a shear flow or cross flow. The interaction potential model is highly versatile, computationally efficient and can be easily incorporated into generic single phase fluid solvers to also simulate complex fluid-structure interaction problems. This is shown by simulating flow in the left ventricle of the heart with mechanical and natural mitral valves where the imposed flow, motion of ventricle and valves dynamically govern the behaviour of each other. Results from these simulations are compared with ad-hoc in-house experimental measurements. Finally, we present a simple and easy to implement parallelisation scheme, as high performance computing is unavoidable when studying large scale problems involving several thousands of simultaneously deforming bodies in highly turbulent flows.

  19. Embedded Fragments from U.S. Military Personnel—Chemical Analysis and Potential Health Implications

    Directory of Open Access Journals (Sweden)

    José A. Centeno

    2014-01-01

    microspectroscopy (CLRM. Quantitative chemical analysis of both fragments and available tissues was conducted employing ICP-MS. Results: Over 800 fragments have been characterized and included as part of the Joint Pathology Center Embedded Fragment Registry. Most fragments were obtained from penetrating wounds sustained to the extremities, particularly soft tissue injuries. The majority of the fragments were primarily composed of a single metal such as iron, copper, or aluminum with traces of antimony, titanium, uranium, and lead. One case demonstrated tungsten in both the fragment and the connected tissue, together with lead. Capsular tissue and fragments from a case from the 1991 Kuwait conflict showed evidence of uranium that was further characterized by uranium isotopic ratios analysis to contain depleted uranium. Conclusions: The present study provides a systematic approach for obtaining a full chemical characterization of retained embedded fragments. Given the vast number of combat casualties with retained fragments, it is expected that fragment analysis will have significant implications for the optimal short and long-term care of wounded service members.

  20. Embedded Fragments from U.S. Military Personnel—Chemical Analysis and Potential Health Implications

    Science.gov (United States)

    Centeno, José A.; Rogers, Duane A.; van der Voet, Gijsbert B.; Fornero, Elisa; Zhang, Lingsu; Mullick, Florabel G.; Chapman, Gail D.; Olabisi, Ayodele O.; Wagner, Dean J.; Stojadinovic, Alexander; Potter, Benjamin K.

    2014-01-01

    microspectroscopy (CLRM). Quantitative chemical analysis of both fragments and available tissues was conducted employing ICP-MS. Results: Over 800 fragments have been characterized and included as part of the Joint Pathology Center Embedded Fragment Registry. Most fragments were obtained from penetrating wounds sustained to the extremities, particularly soft tissue injuries. The majority of the fragments were primarily composed of a single metal such as iron, copper, or aluminum with traces of antimony, titanium, uranium, and lead. One case demonstrated tungsten in both the fragment and the connected tissue, together with lead. Capsular tissue and fragments from a case from the 1991 Kuwait conflict showed evidence of uranium that was further characterized by uranium isotopic ratios analysis to contain depleted uranium. Conclusions: The present study provides a systematic approach for obtaining a full chemical characterization of retained embedded fragments. Given the vast number of combat casualties with retained fragments, it is expected that fragment analysis will have significant implications for the optimal short and long-term care of wounded service members. PMID:24464236

  1. Cognitive behaviour therapy and inflammation: A systematic review of its relationship and the potential implications for the treatment of depression.

    Science.gov (United States)

    Lopresti, Adrian L

    2017-06-01

    There is growing evidence confirming increased inflammation in a subset of adults with depression. The impact of this relationship has mostly been considered in biologically based interventions; however, it also has potential implications for psychological therapies. Cognitive behaviour therapy is the most commonly used psychological intervention for the treatment of depression with theories around its efficacy primarily based on psychological mechanisms. However, cognitive behaviour therapy may have an effect on, and its efficacy influenced by, physiological processes associated with depression. Accordingly, the purpose of this systematic review was to examine the relationship between cognitive behaviour therapy and inflammation. Studies examining the anti-inflammatory effects of cognitive behaviour therapy in people with depression and other medical conditions (e.g. cancer, diabetes and heart disease) were examined. In addition, the relationship between change in inflammatory markers and change in depressive symptoms following cognitive behaviour therapy, and the influence of pre-treatment inflammation on cognitive behaviour therapy treatment response were reviewed. A total of 23 studies investigating the anti-inflammatory effects of cognitive behaviour therapy were identified. In 14 of these studies, at least one reduction in an inflammatory marker was reported, increases were identified in three studies and no change was found in six studies. Three studies examined the relationship between change in inflammation and change in depressive symptoms following cognitive behaviour therapy. In two of these studies, change in depressive symptoms was associated with a change in at least one inflammatory marker. Finally, three studies examined the influence of pre-treatment inflammation on treatment outcome from cognitive behaviour therapy, and all indicated a poorer treatment response in people with higher premorbid inflammation. Preliminary evidence suggests

  2. Life History theory hypotheses on child growth: Potential implications for short and long-term child growth, development and health.

    Science.gov (United States)

    Said-Mohamed, Rihlat; Pettifor, John M; Norris, Shane A

    2018-01-01

    Life history theory integrates ecological, physiological, and molecular layers within an evolutionary framework to understand organisms' strategies to optimize survival and reproduction. Two life history hypotheses and their implications for child growth, development, and health (illustrated in the South African context) are reviewed here. One hypothesis suggests that there is an energy trade-off between linear growth and brain growth. Undernutrition in infancy and childhood may trigger adaptive physiological mechanisms prioritizing the brain at the expense of body growth. Another hypothesis is that the period from conception to infancy is a critical window of developmental plasticity of linear growth, the duration of which may vary between and within populations. The transition from infancy to childhood may mark the end of a critical window of opportunity for improving child growth. Both hypotheses emphasize the developmental plasticity of linear growth and the potential determinants of growth variability (including the role of parent-offspring conflict in maternal resources allocation). Implications of these hypotheses in populations with high burdens of undernutrition and infections are discussed. In South Africa, HIV/AIDS during pregnancy (associated with adverse birth outcomes, short duration of breastfeeding, and social consequences) may lead to a shortened window of developmental plasticity of growth. Furthermore, undernutrition and infectious diseases in children living in South Africa, a country undergoing a rapid nutrition transition, may have adverse consequences on individuals' cognitive abilities and risks of cardio-metabolic diseases. Studies are needed to identify physiological mechanisms underlying energy allocation between biological functions and their potential impacts on health. © 2017 Wiley Periodicals, Inc.

  3. Occurrence and growth of yeasts in processed meat products - implications for potential spoilage

    DEFF Research Database (Denmark)

    Nielsen, Dennis Sandris; Jacobsen, Tomas; Jespersen, Lene

    2008-01-01

    Spoilage of meat products is in general attributed to bacteria but new processing and storage techniques inhibiting growth of bacteria may provide opportunities for yeasts to dominate the microflora and cause spoilage of the product. With the aim of obtaining a deeper understanding of the potential...... role of yeast in spoilage of five different processed meat products (bacon, ham, salami and two different liver patés), yeasts were isolated, enumerated and identified during processing, in the final product and in the final product at the end of shelf life. Yeasts were isolated along the bacon...... of the processed meat products. The yeast microflora was complex with 4-12 different species isolated from the different production sites. In general, Candida zeylanoides, Debaryomyces hansenii and the newly described Candida alimentaria were found to be the dominant yeast species. In addition, three putatively...

  4. Forward-looking farmers owning multiple potential wetland restoration sites: implications for efficient restoration

    Science.gov (United States)

    Schroder (Kushch), Svetlana; Lang, Zhengxin; Rabotyagov, Sergey

    2018-04-01

    Wetland restoration can increase the provision of multiple non-market ecosystem services. Environmental and socio-economic factors need to be accounted for when land is withdrawn from agriculture and wetlands are restored. We build multi-objective optimization models to provide decision support for wetland restoration in the Le Sueur river watershed in Southern Minnesota. We integrate environmental objectives of sediment reduction and habitat protection with socio-economic factors associated with the overlap of private land with potential wetland restoration sites in the watershed and the costs representing forward-looking farmers voluntarily taking land out of agricultural production in favor of wetland restoration. Our results demonstrate that the inclusion of these factors early on in the restoration planning process affects both the total costs of the restoration project and the spatial distribution of optimally selected wetland restoration sites.

  5. Western Pacific Tropospheric Ozone and Potential Vorticity: Implications for Asian Pollution

    Science.gov (United States)

    Browell, Edward V.; Newell, Reginald E.; Davis, Douglas D.; Liu, Shaw C.

    1997-01-01

    Tropospheric ozone (03) cross sections measured with lidar from a DC-8 aircraft over the western Pacific correspond closely with potential vorticity (PV). Both are transported from the middle latitude stratosphere, although this is not the only source of 03, and both have sinks in the tropical boundary layer. 03 and PV are good indicators of photochemical and transport process interactions. In summer, some Asian pollution, raised by convection to the upper troposphere, passes southward into the tropics and to the Southern Hemisphere. In winter, subsidence keeps the pollution at low altitudes where it moves over the ocean towards the Inter-Tropical Convergence Zone (ITCZ), with photochemical destruction and secondary pollutant generation occurring en route. Convection raises this modified air to the upper troposphere, where some re may enter the stratosphere. Thus winter Asian pollution may at have a smaller direct influence on the global atmosphere than it would if injected at other longitudes and seasons.

  6. The maternal brain under stress: Consequences for adaptive peripartum plasticity and its potential functional implications.

    Science.gov (United States)

    Slattery, David A; Hillerer, Katharina M

    2016-04-01

    The peripartum period represents a time during which all mammalian species undergo substantial physiological and behavioural changes, which prepare the female for the demands of motherhood. In addition to behavioural and physiological alterations, numerous brain regions, such as the medial prefrontal cortex, olfactory bulb, medial amygdala and hippocampus are subject to substantial peripartum-associated neuronal, dendritic and synaptic plasticity. These changes, which are temporally- and spatially-distinct, are strongly influenced by gonadal and adrenal hormones, such as estrogen and cortisol/corticosterone, which undergo dramatic fluctuations across this period. In this review, we describe our current knowledge regarding these plasticity changes and describe how stress affects such normal adaptations. Finally, we discuss the mechanisms potentially underlying these neuronal, dendritic and synaptic changes and their functional relevance for the mother and her offspring. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Inhibition of enzyme activity by nanomaterials: potential mechanisms and implications for nanotoxicity testing.

    Science.gov (United States)

    Maccormack, Tyson J; Clark, Rhett J; Dang, Michael K M; Ma, Guibin; Kelly, Joel A; Veinot, Jonathan G C; Goss, Greg G

    2012-08-01

    The objective of this study was to investigate whether nanoparticle-exposure affects enzyme function and to determine the mechanisms responsible. Silicon, Au, and CdSe nanoparticles were synthesized in house and their physicochemical properties were characterized. The activity of purified lactate dehydrogenase (LDH) was inhibited or abolished by all nanoparticles tested. Inhibition was dependent upon particle core and surface-functional group composition. Inhibition of LDH was absent in crude tissue homogenates, in the presence of albumin, and at the isoelectric point of the protein, indicating that nanoparticles bind non-specifically to abundant proteins via a charge interaction. Circular dichroism spectroscopy suggests that the structure of LDH may be altered by nanoparticles in a manner different from that of bulk controls. We present new data on the specific physicochemical properties of nanoparticles that may lead to bioactivity and highlight a number of potentially serious problems with common nanotoxicity testing methods.

  8. Contrasting optical properties of surface waters across the Fram Strait and its potential biological implications

    DEFF Research Database (Denmark)

    Pavlov, Alexey K.; Granskog, Mats A.; Stedmon, Colin A.

    2015-01-01

    Spitsbergen Current (WSC) differ with regards to temperature, salinity and optical properties. We present data on absorption properties of CDOM and particles across the Fram Strait (along 79° N), comparing Polar and Atlantic surface waters in September 2009 and 2010. CDOM absorption of Polar water in the EGC...... budget in the upper 0-10m shifts across Fram Strait. Under water spectral irradiance profiles were generated using ECOLIGHT 5.4.1 and the results indicate that the shift in composition between dissolved and particulate material does not influence substantially the penetration of photosynthetic active...... radiation (PAR, 400-700nm), but does result in notable differences in ultraviolet (UV) light penetration, with higher attenuation in the EGC. Future changes in the Arctic Ocean system will likely affect EGC through diminishing sea-ice cover and potentially increasing CDOM export due to increase in river...

  9. Draft genome sequence of Microbacterium oleivorans strain Wellendorf implicates heterotrophic versatility and bioremediation potential

    Directory of Open Access Journals (Sweden)

    Anton P. Avramov

    2016-12-01

    Full Text Available Microbacterium oleivorans is a predominant member of hydrocarbon-contaminated environments. We here report on the genomic analysis of M. oleivorans strain Wellendorf th