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Sample records for resistance membrane time

  1. Fouling resistant membrane spacers

    KAUST Repository

    Ghaffour, Noreddine

    2017-10-12

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

  2. Solvent-resistant microporous polymide membranes

    Science.gov (United States)

    Miller, Warren K.; McCray, Scott B.; Friesen, Dwayne T.

    1998-01-01

    An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

  3. Fire Resistant, Moisture Barrier Membrane

    Science.gov (United States)

    St.Clair, Terry L. (Inventor)

    2000-01-01

    A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

  4. Salt Concentration Differences Alter Membrane Resistance in Reverse Electrodialysis Stacks

    KAUST Repository

    Geise, Geoffrey M.

    2014-01-14

    Membrane ionic resistance is usually measured by immersing the membrane in a salt solution at a single, fixed concentration. While salt concentration is known to affect membrane resistance when the same concentration is used on both sides of the membrane, little is known about membrane resistance when the membrane is placed between solutions of different concentrations, such as in a reverse electrodialysis (RED) stack. Ionic resistance measurements obtained using Selemion CMV and AMV that separated sodium chloride and ammonium bicarbonate solutions of different concentrations were greater than those measured using only the high-concentration solution. Measured RED stack resistances showed good agreement with resistances calculated using an equivalent series resistance model, where the membranes accounted for 46% of the total stack resistance. The high area resistance of the membranes separating different salt concentration solutions has implications for modeling and optimizing membranes used in RED systems.

  5. Altered membrane permeability in multidrug resistant Escherichia ...

    African Journals Online (AJOL)

    The study was conducted with the objective of examining the outer membrane proteins and their involvement during the transport of β - lactams in multidrug resistant Escherichia coli isolated from extra-intestinal infections. Also, the response of gram negative bacterial biomembrane alteration was studied using extended ...

  6. Porous polymeric membranes with thermal and solvent resistance

    KAUST Repository

    Pulido, Bruno

    2017-05-30

    Polymeric membranes are highly advantageous over their ceramic counterparts in terms of the simplicity of the manufacturing process, cost and scalability. Their main disadvantages are low stability at temperatures above 200 °C, and in organic solvents. We report for the first time porous polymeric membranes manufactured from poly(oxindolebiphenylylene) (POXI), a polymer with thermal stability as high as 500 °C in oxidative conditions. The membranes were prepared by solution casting and phase inversion by immersion in water. The asymmetric porous morphology was characterized by scanning electronic microscopy. The pristine membranes are stable in alcohols, acetone, acetonitrile and hexane, as well as in aqueous solutions with pH between 0 and 14. The membrane stability was extended for application in other organic solvents by crosslinking, using various dibromides, and the efficiency of the different crosslinkers was evaluated by thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). POXI crosslinked membranes are stable up to 329 °C in oxidative conditions and showed organic solvent resistance in polar aprotic solvents with 99% rejection of Red Direct 80 in DMF at 70 °C. With this development, the application of polymeric membranes could be extended to high temperature and harsh environments, fields currently dominated by ceramic membranes.

  7. On the resistances of membrane, diffusion boundary layer and double layer in ion exchange membrane transport

    NARCIS (Netherlands)

    Dlugolecki, P.E.; Ogonowski, Piotr; Metz, S.J.; Saakes, Michel; Nijmeijer, Dorothea C.; Wessling, Matthias

    2010-01-01

    Membrane resistances are often measured under direct current conditions using a standard 0.5 M NaCl characterization solution, although several electro-membrane processes (e.g. reverse electrodialysis, electrodialysis, fuel cells, microbial fuel cells and membrane capacitive deionization) operate in

  8. Fatty acid profiles from the plasma membrane and detergent resistant membranes of two plant species.

    Science.gov (United States)

    Carmona-Salazar, Laura; El Hafidi, Mohammed; Gutiérrez-Nájera, Nora; Noyola-Martínez, Liliana; González-Solís, Ariadna; Gavilanes-Ruíz, Marina

    2015-01-01

    It is essential to establish the composition of the plant plasma membrane in order to understand its organization and behavior under continually changing environments. Knowledge of the lipid phase, in particular the fatty acid (FA) complex repertoire, is important since FAs determine many of the physical-chemical membrane properties. FAs are constituents of the membrane glycerolipid and sphingolipid backbones and can also be linked to some sterols. In addition, FAs are components of complex lipids that can constitute membrane micro-domains, and the use of detergent-resistant membranes is a common approach to study their composition. The diversity and cellular allocation of the membrane lipids containing FAs are very diverse and the approaches to analyze them provide only general information. In this work, a detailed FA analysis was performed using highly purified plasma membranes from bean leaves and germinating maize embryos and their respective detergent-resistant membrane preparations. The analyses showed the presence of a significant amount of very long chain FAs (containing 28C, 30C and 32C), in both plasma membrane preparations from bean and maize, that have not been previously reported. Herein is demonstrated that a significant enrichment of very long chain saturated FAs and saturated FAs can occur in detergent-resistant membrane preparations, as compared to the plasma membranes from both plant species. Considering that a thorough analysis of FAs is rarely performed in purified plasma membranes and detergent-resistant membranes, this work provides qualitative and quantitative evidence on the contributions of the length and saturation of FAs to the organization of the plant plasma membrane and detergent-resistant membranes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Altered membrane permeability in multidrug resistant Escherichia ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... involvement during the transport of β - lactams in multidrug resistant Escherichia coli isolated from extra-intestinal infections. Also, the ... lactam resistance in multidrug resistant E. coli in ESBL and non-ESBL isolates. .... and decreased susceptibility to carbapenems, particularly ertapenem (Perez et al.,.

  10. Altered membrane permeability in multidrug resistant Escherichia ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    filled channels that permit the diffusion of small hydrophilic solutes like β-lactam anti- biotics across the outer membrane (Nikaido et al., 1983;. Varadhachary and Maloney, 1990; Martinez-Martinez et al., 2002). Two major porins ...

  11. Method of making sulfur-resistant composite metal membranes

    Science.gov (United States)

    Way, J Douglas [Boulder, CO; Lusk, Mark [Golden, CO; Thoen, Paul [Littleton, CO

    2012-01-24

    The invention provides thin, hydrogen-permeable, sulfur-resistant membranes formed from palladium or palladium-alloy coatings on porous, ceramic or metal supports. Also disclosed are methods of making these membranes via sequential electroless plating techniques, wherein the method of making the membrane includes decomposing any organic ligands present on the substrate, reducing the palladium crystallites on the substrate to reduced palladium crystallites, depositing a film of palladium metal on the substrate and then depositing a second, gold film on the palladium film. These two metal films are then annealed at a temperature between about 200.degree. C. and about 1200.degree. C. to form a sulfur-resistant, composite PdAu alloy membrane.

  12. Membrane microdomains, rafts, and detergent-resistant membranes in plants and fungi

    Czech Academy of Sciences Publication Activity Database

    Malínský, Jan; Opekarová, Miroslava; Grossmann, G.; Tanner, W.

    2013-01-01

    Roč. 64, April (2013), s. 501-529 ISSN 1543-5008 R&D Projects: GA ČR(CZ) GAP302/11/0146; GA ČR GAP205/12/0720 Institutional research plan: CEZ:AV0Z50390703 Institutional support: RVO:61388971 ; RVO:68378041 Keywords : membrane microdomain * lipid raft * detergent resistant membranes Subject RIV: EB - Genetics ; Molecular Biology; EA - Cell Biology (MBU-M) Impact factor: 18.900, year: 2013

  13. Gas Separation Using Organic-Vapor-Resistent Membranes In Conjunctin With Organic-Vapor-Selective Membranes

    Science.gov (United States)

    Baker, Richard W.; Pinnau, Ingo; He, Zhenjie; Da Costa, Andre R.; Daniels, Ramin; Amo, Karl D.; Wijmans, Johannes G.

    2003-06-03

    A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other selective for the second gas over the organic vapor. The second-gas-selective membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons. The membrane steps can be combined in either order.

  14. Crosslinked copolyazoles with a zwitterionic structure for organic solvent resistant membranes

    KAUST Repository

    Chisca, Stefan

    2015-01-01

    The preparation of crosslinked membranes with a zwitterionic structure based on a facile reaction between a newly synthesized copolyazole with free OH groups and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) is reported. The new OH-functionalized copolyazole is soluble in common organic solvents, such as tetrahydrofuran (THF), dimethylsulfoxide (DMSO), N,N′-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) and can be easily processed by phase inversion. After crosslinking with GPTMS, the membranes acquire high solvent resistance. We show the membrane performance and the influence of the crosslinking reaction conditions on the thermal stability, surface polarity, pore morphology, and solvent resistance. By using UV-spectroscopy we monitored the solvent resistance of the membranes in four aggressive solvents (THF, DMSO, DMF and NMP) for 30 days. After this time, only minor changes (less than 2%) were detected for membranes subjected to a crosslinking reaction for 6 hours or longer. Our data suggest that the novel crosslinked membranes can be used for industrial applications in wide harsh environments in the presence of organic solvents.

  15. Wetting Resistance of Commercial Membrane Distillation Membranes in Waste Streams Containing Surfactants and Oil

    Directory of Open Access Journals (Sweden)

    Lies Eykens

    2017-01-01

    Full Text Available Water management is becoming increasingly challenging and several technologies, including membrane distillation (MD are emerging. This technology is less affected by salinity compared to reverse osmosis and is able to treat brines up to saturation. The focus of MD research recently shifted from seawater desalination to industrial applications out of the scope of reverse osmosis. In many of these applications, surfactants or oil traces are present in the feed stream, lowering the surface tension and increasing the risk for membrane wetting. In this study, the technological boundaries of MD in the presence of surfactants are investigated using surface tension, contact angle and liquid entry pressure measurements together with lab-scale MD experiments to predict the wetting resistance of different membranes. Synthetic NaCl solutions mixed with sodium dodecyl sulfate (SDS were used as feed solution. The limiting surfactant concentration was found to be dependent on the surface chemistry of the membrane, and increased with increasing hydrophobicity and oleophobicity. Additionally, a hexadecane/SDS emulsion was prepared with a composition simulating produced water, a waste stream in the oil and gas sector. When hexadecane is present in the emulsion, oleophobic membranes are able to resist wetting, whereas polytetrafluoretheen (PTFE is gradually wetted by the feed liquid.

  16. Lipids that determine detergent resistance of MDCK cell membrane fractions.

    Science.gov (United States)

    Manni, Marco M; Cano, Ainara; Alonso, Cristina; Goñi, Félix M

    2015-10-01

    A comparative lipidomic study has been performed of whole Madin-Darby canine kidney epithelial cells and of the detergent-resistant membrane fraction (DRM) obtained after treating the cells with the non-ionic detergent Triton X-100. The DRM were isolated following a standard procedure that is extensively used in cell biology studies. Significant differences were found in the lipid composition of the whole cells and of DRM. The latter were enriched in all the analyzed sphingolipid classes: sphingomyelins, ceramides and hexosylceramides. Diacylglycerols were also preferentially found in DRM. The detergent-resistant fraction was also enriched in saturated over unsaturated fatty acyl chains, and in sn-1 acyl chains containing 16 carbon atoms, over the longer and shorter ones. The glycerophospholipid species phosphatidylethanolamines and phosphatidylinositols, that were mainly unsaturated, did not show a preference for DRM. Phosphatidylcholines were an intermediate case: the saturated, but not the unsaturated species were found preferentially in DRM. The question remains on whether these DRM, recovered from detergent-membrane mixtures by floatation over a sucrose gradient, really correspond to membrane domains existing in the cell membrane prior to detergent treatment. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

    KAUST Repository

    Geise, Geoffrey M.

    2013-10-23

    Salinity gradient energy technologies, such as reverse electrodialysis (RED) and capacitive mixing based on Donnan potential (Capmix CDP), could help address the global need for noncarbon-based energy. Anion exchange membranes (AEMs) are a key component in these systems, and improved AEMs are needed in order to optimize and extend salinity gradient energy technologies. We measured ionic resistance and permselectivity properties of quaternary ammonium-functionalized AEMs based on poly(sulfone) and poly(phenylene oxide) polymer backbones and developed structure-property relationships between the transport properties and the water content and fixed charge concentration of the membranes. Ion transport and ion exclusion properties depend on the volume fraction of water in the polymer membrane, and the chemical nature of the polymer itself can influence fine-tuning of the transport properties to obtain membranes with other useful properties, such as chemical and dimensional stability. The ionic resistance of the AEMs considered in this study decreased by more than 3 orders of magnitude (i.e., from 3900 to 1.6 Ω m) and the permselectivity decreased by 6% (i.e., from 0.91 to 0.85) as the volume fraction of water in the polymer was varied by a factor of 3.8 (i.e., from 0.1 to 0.38). Water content was used to rationalize a tradeoff relationship between the permselectivity and ionic resistance of these AEMs whereby polymers with higher water content tend to have lower ionic resistance and lower permselectivity. The correlation of ion transport properties with water volume fraction and fixed charge concentration is discussed with emphasis on the importance of considering water volume fraction when interpreting ion transport data. © 2013 American Chemical Society.

  18. Characterizing the malignancy and drug resistance of cancer cells from their membrane resealing response

    Science.gov (United States)

    Hui, T. H.; Zhou, Z. L.; Fong, H. W.; Ngan, Roger K. C.; Lee, T. Y.; Au, Joseph S. K.; Ngan, A. H. W.; Yip, Timothy T. C.; Lin, Y.

    2016-05-01

    In this report, we showed that two tumor cell characteristics, namely the malignancy and drug-resistance status can be evaluated by their membrane resealing response. Specifically, membrane pores in a number of pairs of cancer and normal cell lines originated from nasopharynx, lung and intestine were introduced by nano-mechanical puncturing. Interestingly, such nanometer-sized holes in tumor cells can reseal ~2-3 times faster than those in the corresponding normal cells. Furthermore, the membrane resealing time in cancer cell lines exhibiting resistance to several leading chemotherapeutic drugs was also found to be substantially shorter than that in their drug-sensitive counterparts, demonstrating the potential of using this quantity as a novel marker for future cancer diagnosis and drug resistance detection. Finally, a simple model was proposed to explain the observed resealing dynamics of cells which suggested that the distinct response exhibited by normal, tumor and drug resistant cells is likely due to the different tension levels in their lipid membranes, a conclusion that is also supported by direct cortical tension measurement.

  19. The electrolysis time on electrosynthesis of hydroxyapatite with bipolar membrane

    Science.gov (United States)

    Nur, Adrian; Jumari, Arif; Budiman, Anatta Wahyu; Puspitaningtyas, Stella Febianti; Cahyaningrum, Suci; Nazriati, Nazriati; Fajaroh, Fauziatul

    2018-02-01

    The electrochemical method with bipolar membrane has been successfully used for the synthesis of hydroxyapatite. In this work, we have developed 2 chambers electrolysis system separated by a bipolar membrane. The membrane was used to separate cations (H+ ions produced by the oxidation of water at the anode) and anions (OH- ions produced by the reduction of water at the cathode). With this system, we have designed that OH- ions still stay in the anions chamber because OH- ions was very substantial in the hydroxyapatite particles formation. The aim of this paper was to compare the electrolysis time on electrosynthesis of hydroxyapatite with and without the bipolar membrane. The electrosynthesis was performed at 500 mA/cm2 for 0.5 to 2 hours at room temperature and under ultrasonic cleaner to void agglomeration with and without the bipolar membrane. The electrosynthesis of hydroxyapatite with the bipolar membrane more effective than without the bipolar membrane. The hydroxyapatite has been appeared at 0.5 h of the electrolysis time with the bipolar membrane (at the cathode chamber) while it hasn't been seen without the bipolar membrane. The bipolar membrane prevents OH- ions migrate to the cation chamber. The formation of HA becomes more effective because OH- ions just formed HA particle.

  20. Effect of pore size on gas resistance of nanofiber membrane by the bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Shen Jing

    2015-01-01

    Full Text Available This paper explores the influence of pore size on gas resistance by comparing micron non-woven and nanofiber membrane. The result shows that membrane with a higher filtration and lower gas resistance can be received by controlling the pore size of nanofiber membrane.

  1. Tailoring Water-Resistant and Breathable Performance of Polyacrylonitrile Nanofibrous Membranes Modified by Polydimethylsiloxane.

    Science.gov (United States)

    Sheng, Junlu; Zhang, Min; Xu, Yue; Yu, Jianyong; Ding, Bin

    2016-10-12

    The demand of water-resistant and breathable materials applied to a separation medium and protective garments is steadily increasing. Typical approaches to obtain these functional materials are based on hydrophobic agents and porous substrates with small fiber diameter, tiny pore, and high porosity. However, a fluorinated hydrophobic finishing agent usually employed in providing effective waterproofness is limited with respect to their environmental persistence and toxic potential. Herein, with the aim to keep a balance between the water-resistance and breathability as well as mechanical properties, we fabricate a novel fluoride-free functional membrane by electrospun polyacrylonitrile (PAN) nanofibers modified with polydimethylsiloxane (PDMS). As determined by morphological, DSC, and FT-IR analyses, the curing reaction of PDMS macromolecules formed an abundance of hydrophobic adhesive structures, which improved the waterproof performance dramatically and imparted relative good breathability at the same time. By systematically tuning the curing temperature as well as the concentration of PDMS, the modified PAN membranes with 4 wt % PDMS possessed good water-resistance (80.9 kPa), modest vapor permeability (12.5 kg m -2 d -1 ), and air permeability (9.9 mm s -1 ). Compared with pristine PAN membranes, the modified membranes were endowed with enhanced tensile stress of 15.7 MPa. The good comprehensive performance of the as-prepared membranes suggested their potential applications in protective clothing, membrane distillation, self-cleaning materials, and other medical products. Furthermore, the proposed relationship between porous structure and waterproof/breathable property as one considerable principle is applicable to designing functional membranes with different levels of protective and comfortable performance.

  2. Solvent and Thermally Resistant Polymeric Membranes for Different Applications

    KAUST Repository

    Taghreeed, Jalal

    2016-11-01

    In this work polymeric materials were developed to be used as a solvent and heat resistance membrane for different applications. In ultrafiltration, poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine®). Polysilsesquioxanes or oligo silsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, allowing 99.2 % rejection of γ-globulin. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100 % tetrahydrofuran. In pervaporation, Novel hydrophobic Hyflon®/Extem® and Hyflon®/PVDF were developed and investigated for ethylene glycol dehydration and n-butanol dehydration respectively. For ethylene glycol different Extem® concentrations were evaluated with regard to both flux and amount of water in the permeate side. Eighteen (18) wt% gave more than 90 wt% water in the permeate. Increasing feed temperature from 25 to 85°C increased the water flux from 31 to 91 g m-2 h-1 when using 5 wt% water in ethylene glycol as feed. The water flux of 40 wt% water:ethylene glycol at 45°C was found to be 350 g m-2 h-1. And for n-butanol dehydration the coating protocols for thin defect-free Hyflon® selective layer on the PVDF support was optimized. Water and n-butanol transport was measured, analyzing the effect of operating conditions. The water flux through the newly developed membranes was higher than 150 g m-2 h-1 with selectivity for water higher than 99 wt%. The membrane application can be extended to other solvents, supporting an effective and simple method for dehydration with hydrophobic membranes. In membrane distillation, PVDF

  3. Multilayer sulfur-resistant composite metal membranes and methods of making and repairing the same

    Science.gov (United States)

    Way, J. Douglas; Hatlevik, Oyvind

    2014-07-15

    The invention relates to thin, hydrogen-permeable, sulfur-resistant membranes formed from multi-layers of palladium or palladium-alloy coatings on porous, ceramic or metal supports, methods of making these membranes, methods of repairing layers of these membranes and devices that incorporate these membranes.

  4. Membrane transporters and drought resistance – a complex issue

    Directory of Open Access Journals (Sweden)

    Karolina Maria Jarzyniak

    2014-12-01

    Full Text Available Land plants have evolved complex adaptation strategies to survive changes in water status in the environment. Understanding the molecular nature of such adaptive changes allows the development of rapid innovations to improve crop performance. Plant membrane transport systems play a significant role when adjusting to water scarcity. Here we put proteins participating in transmembrane allocations of various molecules in the context of stomatal, cuticular and root responses, representing a part of the drought resistance strategy. Their role in the transport of signaling molecules, ions or osmolytes is summarized and the challenge of the forthcoming research, resulting from the recent discoveries, is highlighted.

  5. Resistance of human erythrocyte membranes to Triton X-100 and C12E8.

    Science.gov (United States)

    Crepaldi Domingues, Cleyton; Ciana, Annarita; Buttafava, Armando; Balduini, Cesare; de Paula, Eneida; Minetti, Giampaolo

    2009-01-01

    Lipid rafts are microdomains enriched in cholesterol and sphingolipids that contain specific membrane proteins. The resistance of domains to extraction by nonionic detergents at 4 degrees C is the commonly used method to characterize these structures that are operationally defined as detergent-resistant membranes (DRMs). Because the selectivity of different detergents in defining membrane rafts has been questioned, we have compared DRMs from human erythrocytes prepared with two detergents: Triton X-100 and C12E8. The DRMs obtained presented a cholesterol/protein mass ratio three times higher than in the whole membrane. Flotillin-2 was revealed in trace amounts in DRMs obtained with C12E8, but it was almost completely confined within the DRM fraction with Triton X-100. Differently, stomatin was found distributed in DRM and non-DRM fractions for both detergents. We have also measured the order parameter (S) of nitroxide spin labels inserted into DRMs by means of electron paramagnetic resonance. The 5- and 16-stearic acid spin label revealed significantly higher S values for DRMs obtained with either Triton X-100 or C12E8 in comparison to intact cells, while the difference in the S values between Triton X-100 and C12E8 DRMs was not statistically significant. Our results suggest that although the acyl chain packing is similar in DRMs prepared with either Triton X-100 or C12E8 detergent, protein content is dissimilar, with flotillin-2 being selectively enriched in Triton X-100 DRMs.

  6. A New Insight into Morphology of Solvent Resistant Nano filtration Membranes: Image Processing Assisted Review

    International Nuclear Information System (INIS)

    Pouresmaeel-Selakjani, P.; Jahanshahi, M.; Peyravi, M.; Fauzi Ismail, A.; Nabipoor, M. R.

    2016-01-01

    The aim of this review is to investigate the morphological properties of polyimide based Solvent Resistant Nano filtration membranes by mean of image processing. Effect of phase inversion parameters like polymer concentration, volatile co-solvent, pre-evaporation time, additives in coagulation bath, polymers weight ratio in composite membranes, addition of nano particles and cross-linking agents have been reviewed. The voids of membrane were targeted to survey in the aspect of void area concentration in the scanning electron microscopy micrograph, mean of voids area, voids orientation and circle equivalent diameters of voids. This method by mean of the developed software could make the morphological studies of membranes easy. The population of different measured parameters of the voids could also measure. In conclusion for polyimide based membranes there are specific trends for change in voids properties by changing of phase inversion parameters. It was predictable, but investigated qualitatively up to now and this review can confirm the qualitative observations and also open new discussions about, for example void orientations that are not investigated in any study up to now

  7. The practical use of resistance modelling to interpret the gas separation properties of hollow fiber membranes

    International Nuclear Information System (INIS)

    Ahmad Fauzi Ismail; Shilton, S.J.

    2000-01-01

    A simple resistance modelling methodology is presented for gas transport through asymmetric polymeric membranes. The methodology allows fine structural properties such as active layer thickness and surface porosity, to be determined from experimental gas permeation data. This paper, which could be regarded as a practical guide, shows that resistance modeling, if accompanied by realistic working assumptions, need not be difficult and can provide a valuable insight into the relationships between the membrane fabrication conditions and performance of gas separation membranes. (Author)

  8. Rapid determination of bacterial aminoglycoside resistance in environmental samples using membrane electrospray ionization mass spectrometry.

    Science.gov (United States)

    Fan, Liusheng; Ke, Ming; Yuan, Min; Pu, Ji; Li, Juan; Lu, Jinxing; Xu, Jianguo; Zhang, Mei; Xu, Wei

    2016-08-01

    Antibiotic resistance in pathogenic bacteria is becoming a global public health problem, such as aminoglycoside resistance encoded by the armA gene. Although many methods have been reported, rapid analysis of environmental samples is still challenging. A rapid analytical method was developed in this study to determine bacterial aminoglycoside resistance using membrane electrospray ionization mass spectrometry (MESI-MS). Precursor/product-ion pairs of ArmA unique peptides were detected with minimal sample preparation. Standard peptides were synthesized and used for developing and validating the methodology, and then the method was verified by both ArmA positive and ArmA negative simulated environmental samples. A rapid method for determination of bacterial aminoglycoside resistance was developed using MESI-MS/MS. The bacterial cultural time was optimized to 2 hours, and the precision, accuracy and recovery of this method were investigated. The peptide IHSSTNER (IR-8) unique to ArmA in simulated environmental samples can be successfully identified within 3 hours. The novel assay offered a rapid method to determine bacterial aminoglycoside resistance with high sensitivity, accuracy and precision in simulated environmental samples. This method could also be applied to identify other drug-resistance proteins in clinical/environmental samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  9. Colistin resistance associated with outer membrane protein change in Klebsiella pneumoniae and Enterobacter asburiae.

    Science.gov (United States)

    Kádár, Béla; Kocsis, Béla; Tóth, Ákos; Kristóf, Katalin; Felső, Péter; Kocsis, Béla; Böddi, Katalin; Szabó, Dóra

    2017-06-01

    In this study, outer membrane proteins (OMPs) of colistin-resistant Klebsiella pneumoniae and Enterobacter asburiae were analyzed. One colistin-susceptible and three colistin-resistant K. pneumoniae sequence type 258 strains as well as one colistin-susceptible E. asburiae and its colistin-heteroresistant counterpart strain were involved in the study. OMP analysis of each strain was performed by microchip method. Matrix-assisted laser desorption ionization time of flight/mass spectrometry (MALDI-TOF/MS) investigation was carried out after separation of OMPs by two-dimensional gel electrophoresis and in-gel digestion. The MALDI-TOF/MS analysis of OMPs in the colistin-susceptible K. pneumoniae found 16 kDa proteins belonging to the LysM domain/BON superfamily, as well as DNA starvation proteins, whereas OmpX and OmpW were detected in the colistin-resistant counterpart strains. OmpC and OmpW were detected in the colistin-susceptible E. asburiae, whereas OmpA and OmpX were identified in the colistin-resistant counterpart. This study demonstrated that OMP differences were between colistin-susceptible and -resistant counterpart strains. The altered Gram-negative cell wall may contribute to acquired colistin resistance in Enterobacteriaceae.

  10. Physical–chemical properties, separation performance, and fouling resistance of mixed-matrix ultrafiltration membranes

    KAUST Repository

    Hoek, Eric M.V.

    2011-12-01

    Herein we report on the formation and characterization of mixed-matrix ultrafiltration (UF) membranes hand-cast by nonsolvent induced phase inversion. We evaluated nanometer-to-micrometer sized inorganic fillers (silver, copper, silica, zeolite, and silver-zeolite) materials with polysulfone (PSf) as the polymeric dispersing matrix. In general, mixed-matrix membranes were rougher, more hydrophilic, and more mechanically robust. Only sub-micron zeolite-PSf mixed-matrix membranes exhibited simultaneous improvements in water permeability and solute selectivity; all other mixed-matrix membranes were more permeable, but less selective due to defects associated with poor polymer-filler binding. Protein and bacterial fouling resistance of mixed-matrix membranes containing silver, zeolite, and silver-zeolite nanoparticles were compared to a low-fouling, poly(acrylonitrile) (PAN) UF membrane. Zeolite and silver containing membranes exhibited better protein fouling resistance (due to higher hydrophilicity), whereas silver and silver-zeolite based membranes produce better bacterial fouling resistance due to antimicrobial properties. Overall, zeolite-PSf and silver exchanged zeolite-PSf membranes offered the best combination of improved permeability, selectivity, and fouling resistance - superior to the commercial PAN membrane. © 2011 Elsevier B.V.

  11. Hydrophilic, bactericidal nanoheater-enabled reverse osmosis membranes to improve fouling resistance.

    Science.gov (United States)

    Ray, Jessica R; Tadepalli, Sirimuvva; Nergiz, Saide Z; Liu, Keng-Ku; You, Le; Tang, Yinjie; Singamaneni, Srikanth; Jun, Young-Shin

    2015-06-03

    Polyamide (PA) semipermeable membranes typically used for reverse osmosis water treatment processes are prone to fouling, which reduces the amount and quality of water produced. By synergistically coupling the photothermal and bactericidal properties of graphene oxide (GO) nanosheets, gold nanostars (AuNS), and hydrophilic polyethylene glycol (PEG) on PA reverse osmosis membrane surfaces, we have dramatically improved fouling resistance of these membranes. Batch fouling experiments from three classes of fouling are presented: mineral scaling (CaCO3 and CaSO4), organic fouling (humic acid), and biofouling (Escherichia coli). Systematic analyses and a variety of complementary techniques were used to elucidate fouling resistance mechanisms from each layer of modification on the membrane surface. Both mineral scaling and organic fouling were significantly reduced in PA-GO-AuNS-PEG membranes compared to other membranes. The PA-GO-AuNS-PEG membrane was also effective in killing all near-surface bacteria compared to PA membranes. In the PA-GO-AuNS-PEG membrane, the GO nanosheets act as templates for in situ AuNS growth, which then facilitated localized heating upon irradiation by an 808 nm laser inactivating bacteria on the membrane surface. Furthermore, AuNS in the membrane assisted PEG in preventing mineral scaling on the membrane surface. In flow-through flux and foulant rejection tests, PA-GO-AuNS-PEG membranes performed better than PA membranes in the presence of CaSO4 and humic acid model foulants. Therefore, the newly suggested membrane surface modifications will not only reduce fouling from RO feeds, but can improve overall membrane performance. Our innovative membrane design reported in this study can significantly extend the lifetime and water treatment efficacy of reverse osmosis membranes to alleviate escalating global water shortage from rising energy demands.

  12. The human multidrug resistance-associated protein MRP is a plasma membrane drug-efflux pump

    NARCIS (Netherlands)

    Zaman, G. J.; Flens, M. J.; van Leusden, M. R.; de Haas, M.; Mülder, H. S.; Lankelma, J.; Pinedo, H. M.; Scheper, R. J.; Baas, F.; Broxterman, H. J.

    1994-01-01

    The multidrug-resistance associated protein MRP is a 180- to 195-kDa membrane protein associated with resistance of human tumor cells to cytotoxic drugs. We have investigated how MRP confers drug resistance in SW-1573 human lung carcinoma cells by generating a subline stably transfected with an

  13. Variations in skid resistance over time.

    Science.gov (United States)

    1980-01-01

    The purpose of this project was to quantify the magnitude of changes in skid resistance over time, to isolate the variables that seem most important with respect to the changes, and, to the degree possible, formulate a model for converting skid resis...

  14. Electrical Resistance and Transport Numbers of Ion-Exchange Membranes Used in Electrodialytic Soil Remediation

    DEFF Research Database (Denmark)

    Hansen, Henrik; Ottosen, Lisbeth M.; Villumsen, Arne

    1999-01-01

    Electrodialytic soil remediation is a recently developed method to decontaminate heavy metal polluted soil using ion-exchange membranes. In this method one side of the ion-exchange membrane is in direct contact with the polluted soil. It is of great importance to know if this contact with the soil...... different electrodialytic soil remediation experiments. The experiments showed that after the use in electrodialytic soil remediation, the ion-exchange membranes had transport numbers in the same magnitude as new membranes. The electrical resistance for six membranes did not differ from that of new...

  15. Mechanisms of multidrug resistance in HL60 cells. Analysis of resistance associated membrane proteins and levels of mdr gene expression.

    Science.gov (United States)

    McGrath, T; Latoud, C; Arnold, S T; Safa, A R; Felsted, R L; Center, M S

    1989-10-15

    HL60 cells isolated for resistance to Adriamycin do not contain P-glycoprotein, as determined with immunological probes. These cells, however, are multidrug resistant and defective in the cellular accumulation of drug. In view of these findings, we have examined in greater detail certain properties of the HL60/Adr cells and have compared these properties to an HL60 drug-resistant isolate (HL60/Vinc) which contains high levels of P-glycoprotein. The results of these studies demonstrated that verapamil induces a major increase in cellular drug accumulation in both HL60/Adr and HL60/Vinc isolates. An 125I-labeled photoaffinity analog of verapamil labeled P-glycoprotein contained in membranes of HL60/Vinc cells. In contrast, this agent did not label any protein selectively associated with drug resistance in membranes of the HL60/Adr isolate. The photoactive dihydropyridine calcium channel blocker [3H]azidopine and [125I]NASV, a photoaffinity analog of vinblastine, labelled P-glycoprotein in membranes from HL60/Vinc cells, whereas in experiments with the HL60/Adr isolate there was no detectable labeling of a drug resistance associated membrane protein. Additional studies have been carried out to analyze membrane proteins of HL60/Adr cells labeled with the photoaffinity agent 8-azido-alpha-[32P]ATP (AzATP32). The results demonstrate that this agent labeled a resistance associated membrane protein of 190 kilodaltons (P190). P190 is essentially absent in membranes of drug-sensitive cells. Labeling of P190 with AzATP32 in membranes of resistant cells was blocked completely when incubations were carried out in the presence of excess unlabeled ATP. Additional studies were carried out to analyze mdr gene amplification and expression in sensitive and resistant cells. Experiments carried out with human 5',mdr1 (1.1 kb) and mdr3 (1.0 kb) cDNAs demonstrate that both of these sequences were highly amplified in the HL60/Vinc isolate. Only the mrd1 gene sequence however, was

  16. 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

  17. High-melting lipid mixtures and the origin of detergent-resistant membranes studied with temperature-solubilization diagrams.

    Science.gov (United States)

    Sot, Jesús; Manni, Marco M; Viguera, Ana R; Castañeda, Verónica; Cano, Ainara; Alonso, Cristina; Gil, David; Valle, Mikel; Alonso, Alicia; Goñi, Félix M

    2014-12-16

    The origin of resistance to detergent solubilization in certain membranes, or membrane components, is not clearly understood. We have studied the solubilization by Triton X-100 of binary mixtures composed of egg sphingomyelin (SM) and either ceramide, diacylglycerol, or cholesterol. Solubilization has been assayed in the 4-50°C range, and the results are summarized in a novel, to our knowledge, form of plots, that we have called temperature-solubilization diagrams. Despite using a large detergent excess (lipid/detergent 1:20 mol ratio) and extended solubilization times (24-48 h) certain mixtures were not amenable to Triton X-100 solubilization at one or more temperatures. DSC of all the lipid mixtures, and of all the lipid + detergent mixtures revealed that detergent resistance was associated with the presence of gel domains at the assay temperature. Once the system melted down, solubilization could occur. In general adding high-melting lipids limited the solubilization, whereas the addition of low-melting lipids promoted it. Lipidomic analysis of Madin-Darby canine kidney cell membranes and of the corresponding detergent-resistant fraction indicated a large enrichment of the nonsolubilized components in saturated diacylglycerol and ceramide. SM-cholesterol mixtures were special in that detergent solubilization was accompanied, for certain temperatures and compositions, by an independent phenomenon of reassembly of the partially solubilized lipid bilayers. The temperature at which lysis and reassembly prevailed was ∼25°C, thus for some SM-cholesterol mixtures solubilization occurred both above and below 25°C, but not at that temperature. These observations can be at the origin of the detergent resistance effects observed with cell membranes, and they also mean that cholesterol-containing detergent-resistant membrane remnants cannot correspond to structures existing in the native membrane before detergent addition. Copyright © 2014 Biophysical Society

  18. 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…

  19. Proteomic Analysis of Intracellular and Membrane Proteins From Voriconazole-Resistant Candida glabrata

    OpenAIRE

    Yoo, Jae Il; Kim, Hwa Su; Choi, Chi Won; Yoo, Jung Sik; Yu, Jae Yon; Lee, Yeong Seon

    2013-01-01

    Objectives The proteomic analysis of voriconazole resistant Candida glabrata strain has not yet been investigated. In this study, differentially expressed proteins of intracellular and membrane fraction from voriconazole-susceptible, susceptible dose-dependent (S-DD), resistant C. glabrata strains were compared with each other and several proteins were identified. Methods The proteins of intracellular and membrane were isolated by disrupting cells with glass bead and centrifugation from voric...

  20. Detergent-resistant membranes in human erythrocytes and their ...

    Indian Academy of Sciences (India)

    Unknown

    lation of DRM by density gradient fractionation. Thus, ... as material of low buoyant density in sucrose gradients. 2. Materials and methods. 2.1 Blood processing. Blood was collected from normal human donors after ..... fractionated spectrin-free membranes treated with TX-100 alone, as compared to ghost membranes.

  1. 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...

  2. Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes Affected by Varying Degrees of Fouling on Anaerobic Microfiltration Membranes.

    Science.gov (United States)

    Cheng, Hong; Hong, Pei-Ying

    2017-11-07

    An anaerobic membrane bioreactor was retrofitted with polyvinylidene fluoride (PVDF) microfiltration membrane units, each of which was fouled to a different extent. The membranes with different degrees of fouling were evaluated for their efficiencies in removing three antibiotic-resistant bacteria (ARB), namely, bla NDM-1 -positive Escherichia coli PI-7, bla CTX-M-15 -positive Klebsiella pneumoniae L7, and bla OXA-48 -positive E. coli UPEC-RIY-4, as well as their associated plasmid-borne antibiotic resistance genes (ARGs). The results showed that the log removal values (LRVs) of ARGs correlated positively with the extent of membrane fouling and ranged from 1.9 to 3.9. New membranes with a minimal foulant layer could remove more than 5 log units of ARB. However, as the membranes progressed to subcritical fouling, the LRVs of ARB decreased at increasing operating transmembrane pressures (TMPs). The LRV recovered back to 5 when the membrane was critically fouled, and the achieved LRV remained stable at different operating TMPs. Furthermore, characterization of the surface attributed the removal of both the ARB and ARGs to adsorption, which was facilitated by an increasing hydrophobicity and a decreasing surface ζ potential as the membranes fouled. Our results indicate that both the TMP and the foulant layer synergistically affected ARB removal, but the foulant layer was the main factor that contributed to ARG removal.

  3. Removal of antibiotic-resistant bacteria and antibiotic resistance genes affected by varying degrees of fouling on anaerobic microfiltration membranes

    KAUST Repository

    Cheng, Hong

    2017-09-28

    An anaerobic membrane bioreactor was retrofitted with polyvinylidene fluoride (PVDF) microfiltration membrane units, each of which was fouled to a different extent. The membranes with different degrees of fouling were evaluated for their efficiencies in removing three antibiotic-resistant bacteria (ARB), namely, blaNDM-1-positive Escherichia coli PI-7, blaCTX-M-15-positive Klebsiella pneumoniae L7, and blaOXA-48-positive E. coli UPEC-RIY-4, as well as their associated plasmid-borne antibiotic resistance genes (ARGs). The results showed that the log removal values (LRVs) of ARGs correlated positively with the extent of membrane fouling and ranged from 1.9 to 3.9. New membranes with a minimal foulant layer could remove more than 5 log units of ARB. However, as the membranes progressed to subcritical fouling, the LRVs of ARB decreased at increasing operating transmembrane pressures (TMPs). The LRV recovered back to 5 when the membrane was critically fouled, and the achieved LRV remained stable at different operating TMPs. Furthermore, characterization of the surface attributed the removal of both the ARB and ARGs to adsorption, which was facilitated by an increasing hydrophobicity and a decreasing surface ζ potential as the membranes fouled. Our results indicate that both the TMP and the foulant layer synergistically affected ARB removal, but the foulant layer was the main factor that contributed to ARG removal.

  4. Engineering Hydrophobic Organosilica Nanoparticle-Doped Nanofibers for Enhanced and Fouling Resistant Membrane Distillation

    KAUST Repository

    Hammami, Mohamed Amen

    2016-12-15

    Engineering and scaling-up new materials for better water desalination are imperative to find alternative fresh water sources to meet future demands. Herein, the fabrication of hydrophobic poly(ether imide) composite nanofiber membranes doped with novel ethylene-pentafluorophenylene-based periodic mesoporous organosilica nanoparticles is reported for enhanced and fouling resistant membrane distillation. Novel organosilica nanoparticles were homogeneously incorporated into electrospun nanofiber membranes depicting a proportional increase of hydrophobicity to the particle contents. Direct contact membrane distillation experiments on the organosilica-doped membrane with only 5% doping showed an increase of flux of 140% compared to commercial membranes. The high porosity of organosilica nanoparticles was further utilized to load the eugenol antimicrobial agent which produced a dramatic enhancement of the antibiofouling properties of the membrane of 70% after 24 h.

  5. Engineering Hydrophobic Organosilica Nanoparticle-Doped Nanofibers for Enhanced and Fouling Resistant Membrane Distillation.

    Science.gov (United States)

    Hammami, Mohammed Amen; Croissant, Jonas G; Francis, Lijo; Alsaiari, Shahad K; Anjum, Dalaver H; Ghaffour, Noreddine; Khashab, Niveen M

    2017-01-18

    Engineering and scaling-up new materials for better water desalination are imperative to find alternative fresh water sources to meet future demands. Herein, the fabrication of hydrophobic poly(ether imide) composite nanofiber membranes doped with novel ethylene-pentafluorophenylene-based periodic mesoporous organosilica nanoparticles is reported for enhanced and fouling resistant membrane distillation. Novel organosilica nanoparticles were homogeneously incorporated into electrospun nanofiber membranes depicting a proportional increase of hydrophobicity to the particle contents. Direct contact membrane distillation experiments on the organosilica-doped membrane with only 5% doping showed an increase of flux of 140% compared to commercial membranes. The high porosity of organosilica nanoparticles was further utilized to load the eugenol antimicrobial agent which produced a dramatic enhancement of the antibiofouling properties of the membrane of 70% after 24 h.

  6. Membrane permeabilization of colistin toward pan-drug resistant Gram-negative isolates.

    Science.gov (United States)

    Mohamed, Yasmine Fathy; Abou-Shleib, Hamida Moustafa; Khalil, Amal Mohamed; El-Guink, Nadia Mohamed; El-Nakeeb, Moustafa Ahmed

    2016-01-01

    Pan-drug resistant Gram-negative bacteria, being resistant to most available antibiotics, represent a huge threat to the medical community. Colistin is considered the last therapeutic option for patients in hospital settings. Thus, we were concerned in this study to demonstrate the membrane permeabilizing activity of colistin focusing on investigating its efficiency toward those pan-drug resistant isolates which represent a critical situation. We determined the killing dynamics of colistin against pan-drug resistant isolates. The permeability alteration was confirmed by different techniques as: leakage, electron microscopy and construction of an artificial membrane model; liposomes. Moreover, selectivity of colistin against microbial cells was also elucidated. Colistin was proved to be rapid bactericidal against pan-drug resistant isolates. It interacts with the outer bacterial membrane leading to deformation of its outline, pore formation, leakage of internal contents, cell lysis and finally death. Furthermore, variations in membrane composition of eukaryotic and microbial cells provide a key for colistin selectivity toward bacterial cells. Colistin selectively alters membrane permeability of pan-drug resistant isolates which leads to cell lysis. Colistin was proved to be an efficient last line treatment for pan-drug resistant infections which are hard to treat. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  7. Identification of glycan structure alterations on cell membrane proteins in desoxyepothilone B resistant leukemia cells.

    Science.gov (United States)

    Nakano, Miyako; Saldanha, Rohit; Göbel, Anja; Kavallaris, Maria; Packer, Nicolle H

    2011-11-01

    Resistance to tubulin-binding agents used in cancer is often multifactorial and can include changes in drug accumulation and modified expression of tubulin isotypes. Glycans on cell membrane proteins play important roles in many cellular processes such as recognition and apoptosis, and this study investigated whether changes to the glycan structures on cell membrane proteins occur when cells become resistant to drugs. Specifically, we investigated the alteration of glycan structures on the cell membrane proteins of human T-cell acute lymphoblastic leukemia (CEM) cells that were selected for resistance to desoxyepothilone B (CEM/dEpoB). The glycan profile of the cell membrane glycoproteins was obtained by sequential release of N- and O-glycans from cell membrane fraction dotted onto polyvinylidene difluoride membrane with PNGase F and β-elimination respectively. The released glycan alditols were analyzed by liquid chromatography (graphitized carbon)-electrospray ionization tandem MS. The major N-glycan on CEM cell was the core fucosylated α2-6 monosialo-biantennary structure. Resistant CEM/dEpoB cells had a significant decrease of α2-6 linked sialic acid on N-glycans. The lower α2-6 sialylation was caused by a decrease in activity of β-galactoside α2-6 sialyltransferase (ST6Gal), and decreased expression of the mRNA. It is clear that the membrane glycosylation of leukemia cells changes during acquired resistance to dEpoB drugs and that this change occurs globally on all cell membrane glycoproteins. This is the first identification of a specific glycan modification on the surface of drug resistant cells and the mechanism of this downstream effect on microtubule targeting drugs may offer a route to new interventions to overcome drug resistance.

  8. High Flux, Fouling Resistant Membranes for RO Pretreatment

    Science.gov (United States)

    2012-05-31

    sea water. Basic performance criteria used during development included water flux and retention of bovine serum albumin (BSA) as a benchmark of pore...PAN-g-PEO blend hollow fiber membrane Pure water permeability (L/m2 h MPa) 695 Bovine serum albumin (BSA) rejection (%) 95% Estimated molecular...encounter during coastal operations. The test system at the USBR, including the PgP membrane module in operation on this skid, is shown in Figure 11

  9. Metaxin deficiency alters mitochondrial membrane permeability and leads to resistance to TNF-induced cell killing.

    Science.gov (United States)

    Ono, Koh; Wang, Xiaofei; Kim, Sung Ouk; Armstrong, Lucas C; Bornstein, Paul; Han, Jiahuai

    2010-02-01

    Metaxin, a mitochondrial outer membrane protein, is critical for TNF-induced cell death in L929 cells. Its deficiency, caused by retroviral insertion-mediated mutagenesis, renders L929 cells resistance to TNF killing. In this study, we further characterized metaxin deficiency-caused TNF resistance in parallel with Bcl-X(L) overexpression-mediated death resistance. We did not find obvious change in mitochondria membrane potential in metaxin-deficient (Met(mut)) and Bcl-X(L)-overexpressing cells, but we did find an increase in the release rate of the mitochondrial membrane potential probe rhodamine 123 (Rh123) that was preloaded into mitochondria. In addition, overexpression of a function-interfering mutant of metaxin (MetaΔTM/C) or Bcl-X(L) in MCF-7.3.28 cells also resulted in an acquired resistance to TNF killing and a faster rate of Rh123 release, indicating a close correlation between TNF resistance and higher rates of the dye release from the mitochondria. The release of Rh123 can be controlled by the mitochondrial membrane permeability transition (PT) pore, as targeting an inner membrane component of the PT pore by cyclosporin A (CsA) inhibited Rh123 release. However, metaxin deficiency and Bcl-X(L) overexpression apparently affect Rh123 release from a site(s) different from that of CsA, as CsA can overcome their effect. Though both metaxin and Bcl-X(L) appear to function on the outer mitochondrial membrane, they do not interact with each other. They may use different mechanisms to increase the permeability of Rh123, since previous studies have suggested that metaxin may influence certain outer membrane porins while Bcl-X(L) may form pores on the outer membrane. The alteration of the mitochondrial outer membrane properties by metaxin deficiency and Bcl-X(L) overexpression, as indicated by a quicker Rh123 release, may be helpful in maintaining mitochondrial integrity.

  10. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    KAUST Repository

    Li, Zhenyu

    2017-07-27

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after cleaning with NaOCl and Alconox. Changes in the membrane structure and increased hydrophilicity in the surrounding areas of the aquaporin may be accountable for the increase in water permeability. The membrane shows stable salt rejection up to 99% after all cleaning agents were tested. A 15-day experiment with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane exhibits chemical resistance for most agents used in membrane cleaning procedures, maintaining a stable flux and high salt rejection.

  11. Proteomic Analysis of Intracellular and Membrane Proteins From Voriconazole-Resistant Candida glabrata.

    Science.gov (United States)

    Yoo, Jae Il; Kim, Hwa Su; Choi, Chi Won; Yoo, Jung Sik; Yu, Jae Yon; Lee, Yeong Seon

    2013-12-01

    The proteomic analysis of voriconazole resistant Candida glabrata strain has not yet been investigated. In this study, differentially expressed proteins of intracellular and membrane fraction from voriconazole-susceptible, susceptible dose-dependent (S-DD), resistant C. glabrata strains were compared with each other and several proteins were identified. The proteins of intracellular and membrane were isolated by disrupting cells with glass bead and centrifugation from voriconazole susceptible, S-DD, and resistant C. glabrata strains. The abundance of expressed proteins was compared using two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and proteins showing continuous twofold or more increase or reduction of expression in resistant strains compared to susceptible and S-DD strain were analyzed by liquid chromatography/mass spectrometry-mass spectrometry method. Of 34 intracellular proteins, 15 proteins showed expression increase or reduction (twofold or more). The identified proteins included regulation, energy production, carbohydrate transport, amino acid transport, and various metabolism related proteins. The increase of expression of heat shock protein 70 was found. Among membrane proteins, 12, 31 proteins showed expression increase or decrease in the order of susceptible, S-DD, and resistant strains. This expression included carbohydrate metabolism, amino acid synthesis, and response to stress-related proteins. In membrane fractions, the change of expression of 10 heat shock proteins was observed, and 9 heat shock protein 70 (Hsp70) showed the reduction of expression. The expression of Hsp70 protein in membrane fraction is related to voriconazole resistant C. glabrata strains.

  12. Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen.

    Directory of Open Access Journals (Sweden)

    Sonja Schmidt

    Full Text Available Prostate-specific membrane antigen (PSMA is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009 PLoS One 4: e4608 we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for

  13. Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen

    Science.gov (United States)

    Schmidt, Sonja; Gericke, Birthe; Fracasso, Giulio; Ramarli, Dunia; Colombatti, Marco; Naim, Hassan Y.

    2013-01-01

    Prostate-specific membrane antigen (PSMA) is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs) along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009) PLoS One 4: e4608) we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for utilization of PSMA as

  14. Reduced levels of membrane-bound alkaline phosphatase are common to lepidopteran strains resistant to Cry toxins from Bacillus thuringiensis.

    Science.gov (United States)

    Jurat-Fuentes, Juan Luis; Karumbaiah, Lohitash; Jakka, Siva Rama Krishna; Ning, Changming; Liu, Chenxi; Wu, Kongming; Jackson, Jerreme; Gould, Fred; Blanco, Carlos; Portilla, Maribel; Perera, Omaththage; Adang, Michael

    2011-03-01

    Development of insect resistance is one of the main concerns with the use of transgenic crops expressing Cry toxins from the bacterium Bacillus thuringiensis. Identification of biomarkers would assist in the development of sensitive DNA-based methods to monitor evolution of resistance to Bt toxins in natural populations. We report on the proteomic and genomic detection of reduced levels of midgut membrane-bound alkaline phosphatase (mALP) as a common feature in strains of Cry-resistant Heliothis virescens, Helicoverpa armigera and Spodoptera frugiperda when compared to susceptible larvae. Reduced levels of H. virescens mALP protein (HvmALP) were detected by two dimensional differential in-gel electrophoresis (2D-DIGE) analysis in Cry-resistant compared to susceptible larvae, further supported by alkaline phosphatase activity assays and Western blotting. Through quantitative real-time polymerase chain reaction (qRT-PCR) we demonstrate that the reduction in HvmALP protein levels in resistant larvae are the result of reduced transcript amounts. Similar reductions in ALP activity and mALP transcript levels were also detected for a Cry1Ac-resistant strain of H. armigera and field-derived strains of S. frugiperda resistant to Cry1Fa. Considering the unique resistance and cross-resistance phenotypes of the insect strains used in this work, our data suggest that reduced mALP expression should be targeted for development of effective biomarkers for resistance to Cry toxins in lepidopteran pests.

  15. Reduced levels of membrane-bound alkaline phosphatase are common to lepidopteran strains resistant to Cry toxins from Bacillus thuringiensis.

    Directory of Open Access Journals (Sweden)

    Juan Luis Jurat-Fuentes

    Full Text Available Development of insect resistance is one of the main concerns with the use of transgenic crops expressing Cry toxins from the bacterium Bacillus thuringiensis. Identification of biomarkers would assist in the development of sensitive DNA-based methods to monitor evolution of resistance to Bt toxins in natural populations. We report on the proteomic and genomic detection of reduced levels of midgut membrane-bound alkaline phosphatase (mALP as a common feature in strains of Cry-resistant Heliothis virescens, Helicoverpa armigera and Spodoptera frugiperda when compared to susceptible larvae. Reduced levels of H. virescens mALP protein (HvmALP were detected by two dimensional differential in-gel electrophoresis (2D-DIGE analysis in Cry-resistant compared to susceptible larvae, further supported by alkaline phosphatase activity assays and Western blotting. Through quantitative real-time polymerase chain reaction (qRT-PCR we demonstrate that the reduction in HvmALP protein levels in resistant larvae are the result of reduced transcript amounts. Similar reductions in ALP activity and mALP transcript levels were also detected for a Cry1Ac-resistant strain of H. armigera and field-derived strains of S. frugiperda resistant to Cry1Fa. Considering the unique resistance and cross-resistance phenotypes of the insect strains used in this work, our data suggest that reduced mALP expression should be targeted for development of effective biomarkers for resistance to Cry toxins in lepidopteran pests.

  16. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    DEFF Research Database (Denmark)

    Li, Zhenyu; Linares, Rodrigo Valladares; Bucs, Szilard

    2017-01-01

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused, by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin...... based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after...... with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane...

  17. Use of ceragenins to create novel biofouling resistant water-treatment membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael R.; Altman, Susan Jeanne; Feng, Yanshu (Brigham Young University, Provo, UT); Savage, Paul B. (Brigham Young University, Provo, UT); Pollard, Jacob (Brigham Young University, Provo, UT); Sanchez, Andres L. (LMATA, Albuquerque, NM); Fellows, Benjamin D.; Jones, Howland D. T.; McGrath, Lucas K. (LMATA, Albuquerque, NM)

    2008-12-01

    Scoping studies have demonstrated that ceragenins, when linked to water-treatment membranes have the potential to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced molecules that mimic antimicrobial peptides. Evidence includes measurements of CSA-13 prohibiting the growth of and killing planktonic Pseudomonas fluorescens. In addition, imaging of biofilms that were in contact of a ceragenin showed more dead cells relative to live cells than in a biofilm that had not been treated with a ceragenin. This work has demonstrated that ceragenins can be attached to polyamide reverse osmosis (RO) membranes, though work needs to improve the uniformity of the attachment. Finally, methods have been developed to use hyperspectral imaging with multivariate curve resolution to view ceragenins attached to the RO membrane. Future work will be conducted to better attach the ceragenin to the RO membranes and more completely test the biocidal effectiveness of the ceragenins on the membranes.

  18. Omega 3 fatty acids chemosensitize multidrug resistant colon cancer cells by down-regulating cholesterol synthesis and altering detergent resistant membranes composition.

    OpenAIRE

    Gelsomino, G; Gazzano, E

    2013-01-01

    Background The activity of P-glycoprotein (Pgp) and multidrug resistance related protein 1 (MRP1), two membrane transporters involved in multidrug resistance of colon cancer, is increased by high amounts of cholesterol in plasma membrane and detergent resistant membranes (DRMs). It has never been investigated whether omega 3 polyunsatured fatty acids (PUFAs), which modulate cholesterol homeostasis in dyslipidemic syndromes and have chemopreventive effects in colon cancer, may affect the respo...

  19. Detergent-resistant membranes in human erythrocytes and their ...

    Indian Academy of Sciences (India)

    In cell membranes, local inhomogeneity in the lateral distribution of lipids and proteins is thought to exist in vivo in the form of lipid 'rafts', microdomains enriched in cholesterol and sphingolipids, and in specific classes of proteins, that appear to play specialized roles for signal transduction, cell-cell recognition, parasite or ...

  20. Convenient and rapid removal of detergent from glycolipids in detergent-resistant membrane microdomains.

    Science.gov (United States)

    Suzuki, Yusuke; Kabayama, Kazuya

    2012-03-01

    Although detergents are often essential in protocols, they are usually incompatible with further biochemical analysis. There are several methods for detergent removal, but the procedures are complicated or suffer from sample loss. Here, we describe a convenient and rapid method for detergent removal from sialic acid-containing glycosphingolipids (gangliosides) and neutral glycolipids in detergent-resistant membrane (DRM) microdomain. It is based on selective detergent extraction, in which the sample is dried on a glass tube, followed by washing with organic solvent. We investigated 18 organic solvents and used high performance thin-layer chromatography (HPTLC) and matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS) to confirm that dichloroethane (DCE) was the most suitable solvent and completely removed the nonionic detergent Triton X-100. Furthermore, DCE extraction effectively removed interference caused by other nonionic, zwitterionic, or ionic detergents in MALDI-QIT-TOF MS analysis.

  1. Polyamide desalination membrane characterization and surface modification to enhance fouling resistance.

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mukul M. (Univeristy of Texas at Austin, Austin, TX); Freeman, Benny D. (Univeristy of Texas at Austin, Austin, TX); Van Wagner, Elizabeth M. (Univeristy of Texas at Austin, Austin, TX); Hickner, Michael A. (Pennsylvania State University, University Park, PA); Altman, Susan Jeanne

    2010-08-01

    The market for polyamide desalination membranes is expected to continue to grow during the coming decades. Purification of alternative water sources will also be necessary to meet growing water demands. Purification of produced water, a byproduct of oil and gas production, is of interest due to its dual potential to provide water for beneficial use as well as to reduce wastewater disposal costs. However, current polyamide membranes are prone to fouling, which decreases water flux and shortens membrane lifetime. This research explored surface modification using poly(ethylene glycol) diglycidyl ether (PEGDE) to improve the fouling resistance of commercial polyamide membranes. Characterization of commercial polyamide membrane performance was a necessary first step before undertaking surface modification studies. Membrane performance was found to be sensitive to crossflow testing conditions. Concentration polarization and feed pH strongly influenced NaCl rejection, and the use of continuous feed filtration led to higher water flux and lower NaCl rejection than was observed for similar tests performed using unfiltered feed. Two commercial polyamide membranes, including one reverse osmosis and one nanofiltration membrane, were modified by grafting PEGDE to their surfaces. Two different PEG molecular weights (200 and 1000) and treatment concentrations (1% (w/w) and 15% (w/w)) were studied. Water flux decreased and NaCl rejection increased with PEGDE graft density ({micro}g/cm{sup 2}), although the largest changes were observed for low PEGDE graft densities. Surface properties including hydrophilicity, roughness and charge were minimally affected by surface modification. The fouling resistance of modified and unmodified membranes was compared in crossflow filtration studies using model foulant solutions consisting of either a charged surfactant or an oil in water emulsion containing n-decane and a charged surfactant. Several PEGDE-modified membranes demonstrated improved

  2. Real time visual characterization of membrane fouling and cleaning

    NARCIS (Netherlands)

    Ngene, I.S.

    2010-01-01

    The research presented in this thesis is focused on the phenomena of membrane fouling. Membrane fouling is simply described as the deposition of unwanted matter on the membrane surface during the course of operation, which results in reduction in filtration efficiency. This research is aimed at

  3. Chaos Time Series Prediction Based on Membrane Optimization Algorithms

    Directory of Open Access Journals (Sweden)

    Meng Li

    2015-01-01

    Full Text Available This paper puts forward a prediction model based on membrane computing optimization algorithm for chaos time series; the model optimizes simultaneously the parameters of phase space reconstruction (τ,m and least squares support vector machine (LS-SVM (γ,σ by using membrane computing optimization algorithm. It is an important basis for spectrum management to predict accurately the change trend of parameters in the electromagnetic environment, which can help decision makers to adopt an optimal action. Then, the model presented in this paper is used to forecast band occupancy rate of frequency modulation (FM broadcasting band and interphone band. To show the applicability and superiority of the proposed model, this paper will compare the forecast model presented in it with conventional similar models. The experimental results show that whether single-step prediction or multistep prediction, the proposed model performs best based on three error measures, namely, normalized mean square error (NMSE, root mean square error (RMSE, and mean absolute percentage error (MAPE.

  4. Multiple antibiotic resistance genes distribution in ten large-scale membrane bioreactors for municipal wastewater treatment.

    Science.gov (United States)

    Sun, Yanmei; Shen, Yue-Xiao; Liang, Peng; Zhou, Jizhong; Yang, Yunfeng; Huang, Xia

    2016-12-01

    Wastewater treatment plants are thought to be potential reservoirs of antibiotic resistance genes. In this study, GeoChip was used for analyzing multiple antibiotic resistance genes, including four multidrug efflux system gene groups and three β-lactamase genes in ten large-scale membrane bioreactors (MBRs) for municipal wastewater treatment. Results revealed that the diversity of antibiotic genes varied a lot among MBRs, but about 40% common antibiotic resistance genes were existent. The average signal intensity of each antibiotic resistance group was similar among MBRs, nevertheless the total abundance of each group varied remarkably and the dominant resistance gene groups were different in individual MBR. The antibiotic resistance genes majorly derived from Proteobacteria and Actinobacteria. Further study indicated that TN, TP and COD of influent, temperature and conductivity of mixed liquor were significant (Pantibiotic resistance genes distribution in MBRs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. In Plant and Animal Cells, Detergent-Resistant Membranes Do Not Define Functional Membrane Rafts

    Czech Academy of Sciences Publication Activity Database

    Tanner, W.; Malínský, Jan; Opekarová, Miroslava

    2011-01-01

    Roč. 23, č. 4 (2011), s. 1191-1193 ISSN 1040-4651 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z50200510 Keywords : plasma-membrane * lipod rafts * proteins Subject RIV: EA - Cell Biology Impact factor: 8.987, year: 2011

  6. Enhanced biofouling resistance of polyethersulfone membrane surface modified with capsaicin derivative and itaconic acid

    International Nuclear Information System (INIS)

    Wang, Jian; Gao, Xueli; Wang, Qun; Sun, Haijing; Wang, Xiaojuan; Gao, Congjie

    2015-01-01

    Graphical abstract: - Highlights: • PES membrane was modified with a capsaicin derivative. • UV-assisted graft polymerization was carried out on membrane surface. • The capsaicin derivative modified membrane shows better antibiofouling property. - Abstract: The culprit of biofouling is the reproduction of viable microorganisms on the membrane surface. Recently, functionalization of membrane surface with natural antibacterial agents has drawn great attention. This work presents the fabrication of antibiofouling polyethersulfone (PES) ultrafiltration (UF) membranes by UV-assisted photo grafting of capsaicin derivative (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide, HMBA) and itaconic acid (IA) on the surface of PES membrane. Results of FTIR-ATR, water static contact angle (WSCA) and atomic force microscopy (AFM) analysis confirmed the successful grafting of HMBA and IA on the membrane surface. We investigated the antifouling and antibacterial properties of these membranes using BSA and Escherichia coli as the test model, respectively. During a 150-min test, the modified membranes show much lower flux decline (42.7% for PES-g-1H0I, 22.2% for PES-g-1H1I and 7.7% for PES-g-1H5I) when compared with the pristine membrane (flux declined by 77%). The modified membranes exhibit excellent antibacterial activity (nearly 100%) when UV irradiation time was 6 min. The morphological study suggested that the E. coli on the pristine membrane showed a regular and smooth surface while that on the modified membrane was disrupted, which validated the antibacterial activity of the modified membranes.

  7. Enhanced biofouling resistance of polyethersulfone membrane surface modified with capsaicin derivative and itaconic acid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Xueli, E-mail: gxl_ouc@126.com [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Wang, Qun; Sun, Haijing; Wang, Xiaojuan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Congjie, E-mail: gaocjie@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China)

    2015-11-30

    Graphical abstract: - Highlights: • PES membrane was modified with a capsaicin derivative. • UV-assisted graft polymerization was carried out on membrane surface. • The capsaicin derivative modified membrane shows better antibiofouling property. - Abstract: The culprit of biofouling is the reproduction of viable microorganisms on the membrane surface. Recently, functionalization of membrane surface with natural antibacterial agents has drawn great attention. This work presents the fabrication of antibiofouling polyethersulfone (PES) ultrafiltration (UF) membranes by UV-assisted photo grafting of capsaicin derivative (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide, HMBA) and itaconic acid (IA) on the surface of PES membrane. Results of FTIR-ATR, water static contact angle (WSCA) and atomic force microscopy (AFM) analysis confirmed the successful grafting of HMBA and IA on the membrane surface. We investigated the antifouling and antibacterial properties of these membranes using BSA and Escherichia coli as the test model, respectively. During a 150-min test, the modified membranes show much lower flux decline (42.7% for PES-g-1H0I, 22.2% for PES-g-1H1I and 7.7% for PES-g-1H5I) when compared with the pristine membrane (flux declined by 77%). The modified membranes exhibit excellent antibacterial activity (nearly 100%) when UV irradiation time was 6 min. The morphological study suggested that the E. coli on the pristine membrane showed a regular and smooth surface while that on the modified membrane was disrupted, which validated the antibacterial activity of the modified membranes.

  8. Lipid components in the detergent-resistant membrane microdomain (DRM) obtained from the synaptic plasma membrane of rat brain.

    Science.gov (United States)

    Matsuura, Daisuke; Taguchi, Katsutoshi; Yagisawa, Hitoshi; Maekawa, Shohei

    2007-08-16

    Lateral association of sphingolipids and cholesterol is considered to form membrane microdomains such as "lipid rafts" obtainable as a detergent-resistant membrane microdomain (DRM) fraction after solubilization with a non-ionic detergent and density gradient centrifugation. Since not only sphinogolipids and cholesterol, but also functional lipids such as phosphatidylinositol 4,5-bisphosphate (PIP(2)) are reported to be localized in DRM prepared from several cultured cells, this domain is considered to be a platform mediating lipid-signaling. Although PIP(2) is considered to have pivotal roles in the nervous system, little information is available on the localization of PIP(2) in the DRM within the synaptic plasma membrane (SPM) obtained from matured rat brains. In this study, in order to know the localization of PIP(2) in SPM-derived DRM, we measured the amount of PIP(2) in SPM and SPM-derived DRM, by the thin-layer chromatography blotting method, using a GST-fusion protein of the pleckstrin-homology domain of phospholipase Cdelta1 as a PIP(2) binding probe. About 10% of the PIP(2) in SPM was recovered in DRM. In contrast, over 40% recovery was observed for the membrane cholesterol and sphingomyelin, and about 30% recovery was observed for phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine in the DRM were detected using the thin-layer chromatography method. Since the recovery of proteins in DRM was about 10%, the result indicates that there occurs no enrichment of PIP(2) in DRM prepared from SPM.

  9. Evaluation of hydrogen production and internal resistance in forward osmosis membrane integrated microbial electrolysis cells.

    Science.gov (United States)

    Lee, Mi-Young; Kim, Kyoung-Yeol; Yang, Euntae; Kim, In S

    2015-01-01

    In order to enhance hydrogen production by facilitated proton transport through a forward osmosis (FO) membrane, the FO membrane was integrated into microbial electrolysis cells (MECs). An improved hydrogen production rate was obtained in the FO-MEC (12.5±1.84×10(-3)m(3)H2/m(3)/d) compared to that of the cation exchange membrane (CEM) - MEC (4.42±0.04×10(-3)m(3)H2/m(3)/d) during batch tests (72h). After an internal resistance analysis, it was confirmed that the enhanced hydrogen production in FO-MEC was attributed to the smaller charge transfer resistance than in the CEM-MEC (90.3Ω and 133.4Ω respectively). The calculation of partial internal resistance concluded that the transport resistance can be substantially reduced by replacing a CEM with a FO membrane; decrease of the resistance from 0.069Ωm(2) to 5.99×10(-4)Ωm(2). Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Sub- T g Cross-Linking of a Polyimide Membrane for Enhanced CO 2 Plasticization Resistance for Natural Gas Separation

    KAUST Repository

    Qiu, Wulin

    2011-08-09

    Decarboxylation-induced thermal cross-linking occurs at elevated temperatures (∼15 °C above glass transition temperature) for 6FDA-DAM:DABA polyimides, which can stabilize membranes against swelling and plasticization in aggressive feed streams. Despite this advantage, such a high temperature might result in collapse of substructure and transition layers in the asymmetric structure of a hollow fibers based on such a material. In this work, the thermal cross-linking of the 6FDA-DAM:DABA at temperatures much below the glass transition temperature (∼387 °C by DSC) was demonstrated. This sub-Tg cross-linking capability enables extension to asymmetric structures useful for large scale membranes. The resulting polymer membranes were characterized by swelling in known solvents for the un-cross-linked materials, TGA analysis, and permeation tests of aggressive gas feed stream at higher pressure. The annealing temperature and time clearly influence the degree of cross-linking of the membranes, and results in a slight difference in selectivity for membranes under various cross-linking conditions. Results indicate that the sub-Tg thermal cross-linking of 6FDA-DAM:DABA dense film membrane can be carried out completely even at a temperature as low as 330 °C. Permeabilities were tested for the polyimide membranes using both pure gases (He, O2, N2, CH4, CO2) and mixed gases (CO2/CH4). The selectivity of the cross-linked membrane can be maintained even under very aggressive CO2 operating conditions that are not possible without cross-linking. Moreover, the plasticization resistance was demonstrated up to 700 psia for pure CO 2 gas or 1000 psia for 50% CO2 mixed gas feeds. © 2011 American Chemical Society.

  11. Cochlear aqueduct flow resistance depends on round window membrane position in guinea pigs

    NARCIS (Netherlands)

    Feijen, RA; Segenhout, JM; Albers, FWJ; Wit, HP

    2004-01-01

    The resistance for fluid flow of the cochlear aqueduct was measured in guinea pigs for different positions of the round window membrane. These different positions were obtained by applying different constant pressures to the middle car cavity. Fluid flow through the aqueduct was induced by small

  12. Increased levels of the multidrug resistance protein in lateral membranes of proliferating hepatocyte-derived cells

    NARCIS (Netherlands)

    Roelofsen, H; Vos, TA; Schippers, IJ; Kuipers, F; Moshage, H; Jansen, PLM; Muller, M

    Background & Aims: The multidrug resistance protein (MRP) functions as an organic anion efflux carrier. Recent studies suggest that hepatocytes contain two mrp homologues, named mrp1 and mrp2, localized on the lateral and canalicular membrane, respectively. The aim of this study was to evaluate the

  13. Effect of solid retention time on membrane fouling in membrane bioreactor: from the perspective of quorum sensing and quorum quenching.

    Science.gov (United States)

    Yu, Huarong; Xu, Guoren; Qu, Fangshu; Li, Guibai; Liang, Heng

    2016-09-01

    Solid retention time (SRT) is one of the most important operational parameters in membrane bioreactor (MBR), which significantly influences membrane fouling. It is widely recognized that SRT mainly changes biomass characteristics, and then, influences membrane fouling. Effect of SRT on quorum sensing (QS) in MBR, which could also influence fouling by coordinating biofilm formation, has not been reported. In this study, fouling, QS, soluble microbial products (SMP), and extracellular polymer substances (EPS) in MBRs operated under SRTs of 4, 10, and 40 days were investigated. The results showed that as SRT increased, the abundance of quorum quenching (QQ) bacteria increased, the quorum signal degradation activity of activated sludge increased, the concentrations of signal molecules in MBR decreased, the excretion of SMP and EPS decreased, and thus membrane biofouling was alleviated. Therefore, besides altering the biomass physiochemical properties, SRT also changed the balance between QS and QQ in MBR, and in this way, influenced membrane biofouling.

  14. Helicobacter pylori Antibiotic Resistance: Trends Over Time

    Directory of Open Access Journals (Sweden)

    Raymond G Lahaie

    2000-01-01

    Full Text Available Resistance to antibiotics can be a major problem in the treatment of bacterial infections. As the use of antibiotics increases, bacterial resistance to these agents is rising and in many cases is responsible for the failure of treatment regimens. Although the treatment of Helicobacter pylori infection requires the use of more than one antibiotic to obtain adequate eradication rates, the efficacy of the currently used antibiotic combinations has been shown to be decreased by resistance to one of the antibiotics. The use of antibiotics in regimens for the treatment of H pylori is increasing in many countries, including Canada. This increase is both in the use of these antibiotics alone for the treatment of nongastrointestinal infections and in their use in association with proton pump inhibitors for the treatment of H pylori infection. In several European and Asian countries, where resistance to antibiotics is being monitored, it has been demonstrated that H pylori resistance to metronidazole and to clarithromycin increased throughout the 1990s. Thus far, the data available in Canada do not show increased resistance to either of these antibiotics. As for other antibiotics used in the treatment of H pylori infection, such as tetracycline and amoxicillin, the rate of resistance to these agents is still very low and does not constitute a significant problem. Because the efficacy of the regimens used in the treatment of H pylori infection is compromised by resistance to the antibiotics used, it is important that H pylori resistance rates in Canada and throughout the world continue to be monitored. Only with such reliable data can the most optimal regimens be recommended.

  15. Preparation of Fouling-Resistant Nanofibrous Composite Membranes for Separation of Oily Wastewater

    Directory of Open Access Journals (Sweden)

    Fatma Yalcinkaya

    2017-12-01

    Full Text Available A facile and low-cost method has been developed for separation of oily wastewater. Polyvinylidene fluoride/polyacrylonitrile (PVDF/PAN nanofibers laminated on a supporting layer were tested. In order to create highly permeable and fouling-resistant membranes, surface modifications of both fibers were conducted. The results of oily wastewater separation showed that, after low vacuum microwave plasma treatment with Argon (Ar and chemical modification with sodium hydroxide (NaOH, the membranes had excellent hydrophilicity, due to the formation of active carboxylic groups. However, the membrane performance failed during the cleaning procedures. Titanium dioxide (TiO2 was grafted onto the surface of membranes to give them highly permeable and fouling-resistance properties. The results of the self-cleaning experiment indicated that grafting of TiO2 on the surface of the membranes after their pre-treatment with Ar plasma and NaOH increased the permeability and the anti-fouling properties. A new surface modification method using a combination of plasma and chemical treatment was introduced.

  16. Salicylate-inducible antibiotic resistance in Pseudomonas cepacia associated with absence of a pore-forming outer membrane protein.

    OpenAIRE

    Burns, J L; Clark, D K

    1992-01-01

    The most common mechanism of antibiotic resistance in multiply resistant Pseudomonas cepacia is decreased porin-mediated outer membrane permeability. In some gram-negative organisms this form of antibiotic resistance can be induced by growth in the presence of weak acids, such as salicylates, which suppress porin synthesis. To determine the effects of salicylates on outer membrane permeability of P. cepacia, a susceptible laboratory strain, 249-2, was grown in 10 mM sodium salicylate. Antibio...

  17. Efficacy of antibacterial peptides against peptide-resistant MRSA is restored by permeabilisation of bacteria membranes

    Directory of Open Access Journals (Sweden)

    Joshua Thomas Ravensdale

    2016-11-01

    Full Text Available Clinical application of antimicrobial peptides, as with conventional antibiotics, may be compromised by the development of bacterial resistance. This study investigated antimicrobial peptide resistance in methicillin resistant Staphylococcus aureus, including aspects related to the resilience of the resistant bacteria towards the peptides, the stability of resistance when selection pressures are removed, and whether resistance can be overcome by using the peptides with other membrane-permeabilising agents. Genotypically variant strains of S. aureus became equally resistant to the antibacterial peptides melittin and bac8c when grown in sub-lethal concentrations. Subculture of a melittin-resistant strain without melittin for 8 days lowered the minimal lethal concentration of the peptide from 170 µg ml-1 to 30 g ml-1. Growth for 24 h in 12 g ml-1 melittin restored the MLC to 100 g ml-1. Flow cytometry analysis of cationic fluorophore binding to melittin-naïve and melittin-resistant bacteria revealed that resistance coincided with decreased binding of cationic molecules, suggesting a reduction in nett negative charge on the membrane. Melittin was haemolytic at low concentrations but the truncated analogue of melittin, mel12-26, was confirmed to lack haemolytic activity. Although a previous report found that mel12-26 retained full bactericidal activity, we found it to lack significant activity when added to culture medium. However, electroporation in the presence of 50 µg ml-1 of mel12-26, killed 99.3% of the bacteria. Similarly, using a low concentration of the non-ionic detergent Triton X-100 to permeabilize bacteria to mel12-26 markedly increased its bactericidal activity. The observation that bactericidal activity of the non-membranolytic peptide mel12-26 was enhanced when the bacterial membrane was permeablised by detergents or electroporation, suggests that its principal mechanism in reducing bacterial survival may be through

  18. Thermodynamic Resistance to Matter Flow at The Interface of a Porous Membrane.

    Science.gov (United States)

    Glavatskiy, K S; Bhatia, Suresh K

    2016-04-12

    Nanoporous materials are important in industrial separation, but their application is subject to strong interfacial barriers to the entry and transport of fluids. At certain conditions the fluid inside and outside the nanoporous material can be viewed as a two-phase system, with an interface between them, which poses an excess resistance to matter flow. We show that there exist two kinds of phenomena which influence the interfacial resistance: hydrodynamic effects and thermodynamic effects, which are independent of each other. Here, we investigate the role of the thermodynamic effects in carbon nanotubes (CNTs) and slit pores and compare the associated thermodynmic resistance with that due to hydrodynamic effects traditionally modeled by the established Sampson expression. Using CH4 and CO2 as model fluids, we show that the thermodynamic resistance is especially important for moderate to high pressures, at which the fluid within the CNT or slit pore is in the condensed state. Further, we show that at such pressures the thermodynamic resistance becomes comparable with the internal resistance to fluid transport at length scales typical of membranes used in fuel cells, and of importance in membrane-based separation, and nanofluidics in general.

  19. 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.

  20. Ablation of very long acyl chain sphingolipids causes hepatic insulin resistance in mice due to altered detergent-resistant membranes.

    Science.gov (United States)

    Park, Joo-Won; Park, Woo-Jae; Kuperman, Yael; Boura-Halfon, Sigalit; Pewzner-Jung, Yael; Futerman, Anthony H

    2013-02-01

    Sphingolipids are important structural components of cell membranes and act as critical regulators of cell function by modulating intracellular signaling pathways. Specific sphingolipids, such as ceramide, glucosylceramide, and ganglioside GM3, have been implicated in various aspects of insulin resistance, because they have been shown to modify several steps in the insulin signaling pathway, such as phosphorylation of either protein kinase B (Akt) or of the insulin receptor. We now explore the role of the ceramide acyl chain length in insulin signaling by using a ceramide synthase 2 (CerS2) null mouse, which is unable to synthesize very long acyl chain (C22-C24) ceramides. CerS2 null mice exhibited glucose intolerance despite normal insulin secretion from the pancreas. Both insulin receptor and Akt phosphorylation were abrogated in liver, but not in adipose tissue or in skeletal muscle. The lack of insulin receptor phosphorylation in liver correlated with its inability to translocate into detergent-resistant membranes (DRMs). Moreover, DRMs in CerS2 null mice displayed properties significantly different from those in wild-type mice, suggesting that the altered sphingolipid acyl chain length directly affects insulin receptor translocation and subsequent signaling. We conclude that the sphingolipid acyl chain composition of liver regulates insulin signaling by modifying insulin receptor translocation into membrane microdomains. Copyright © 2012 American Association for the Study of Liver Diseases.

  1. Multidrug Resistance-Associated Protein 2 (MRP2) Mediated Transport of Oxaliplatin-Derived Platinum in Membrane Vesicles

    Science.gov (United States)

    Myint, Khine; Li, Yan; Paxton, James; McKeage, Mark

    2015-01-01

    The platinum-based anticancer drug oxaliplatin is important clinically in cancer treatment. However, the role of multidrug resistance-associated protein 2 (MRP2) in controlling oxaliplatin membrane transport, in vivo handling, toxicity and therapeutic responses is unclear. In the current study, preparations of MRP2-expressing and control membrane vesicles, containing inside-out orientated vesicles, were used to directly characterise the membrane transport of oxaliplatin-derived platinum measured by inductively coupled plasma mass spectrometry. Oxaliplatin inhibited the ATP-dependent accumulation of the model MRP2 fluorescent probe, 5(6)-carboxy-2,'7'-dichlorofluorescein, in MRP2-expressing membrane vesicles. MRP2-expressing membrane vesicles accumulated up to 19-fold more platinum during their incubation with oxaliplatin and ATP as compared to control membrane vesicles and in the absence of ATP. The rate of ATP-dependent MRP2-mediated active transport of oxaliplatin-derived platinum increased non-linearly with increasing oxaliplatin exposure concentration, approaching a plateau value (Vmax) of 2680 pmol Pt/mg protein/10 minutes (95%CI, 2010 to 3360 pmol Pt/mg protein/10 minutes), with the half-maximal platinum accumulation rate (Km) at an oxaliplatin exposure concentration of 301 μM (95% CI, 163 to 438 μM), in accordance with Michaelis-Menten kinetics (r2 = 0.954). MRP2 inhibitors (myricetin and MK571) reduced the ATP-dependent accumulation of oxaliplatin-derived platinum in MRP2-expressing membrane vesicles in a concentration-dependent manner. To identify whether oxaliplatin, or perhaps a degradation product, was the likely substrate for this active transport, HPLC studies were undertaken showing that oxaliplatin degraded slowly in membrane vesicle incubation buffer containing chloride ions and glutathione, with approximately 95% remaining intact after a 10 minute incubation time and a degradation half-life of 2.24 hours (95%CI, 2.08 to 2.43 hours). In

  2. Rhizobium strains differ considerably in outer membrane permeability and polymyxin B resistance.

    Science.gov (United States)

    Komaniecka, Iwona; Zamłyńska, Katarzyna; Zan, Radosław; Staszczak, Magdalena; Pawelec, Jarosław; Seta, Irena; Choma, Adam

    2016-01-01

    Six rhizobium (Rhizobium leguminosarum bv. Trifolii TA1, Sinorhizobium meliloti 1021, Mesorhizobium huakuii IFO 15243(T), Ochrobactrum lupini LUP 21(T), Bradyrhizobium japonicum USDA110 and B. elkanii USDA 76) and two Escherichia coli strains (E. coli ATCC 25922 and E. coli HB 101) were compared in respect to polymyxin B and EDTA resistance, as well as bacterial outer membrane (OM) permeability to a fluorescent hydrophobic agent (N-phenyl-1-naphthylamine - NPN). TEM (Transmission Electron Microscopy) and a microbial test demonstrated that all the rhizobia were much more resistant to polymyxin B in comparison with E. coli strains. EDTA and polymyxin B enhance permeability of B. japonicum and O. lupini OM. Other rhizobia incorporated NPN independently of the presence of membrane-deteriorating agents; however, the level of fluorescence (measured as NPN absorption) was strain dependent.

  3. The role of outer membrane in Serratia marcescens intrinsic resistance to antibiotics.

    Science.gov (United States)

    Sánchez, L; Ruiz, N; Leranoz, S; Viñas, M; Puig, M

    1997-09-01

    Three different porins from Serratia marcescens were described. They were named Omp1, Omp2 and Omp3 and their molecular weights were 42, 40 and 39 kDa respectively. Omp2 and Omp3 showed osmoregulation and thermoregulation in a similar way to OmpC and OmpF of Escherichia coli. Permeability coefficients of the outer membrane of this species were calculated following the Zimmermann and Rosselet method. P values were similar to those obtained in Escherichia coli, which suggests that the chromosomal beta-lactamase would play a major role in the resistance of Serratia marcescens to beta-lactam antibiotics. Both MIC values and permeabilities were modified by salycilates and acetylsalycilate. Synergism between the outer membrane and the beta-lactamase was also evaluated. When bacteria grew in the presence of a beta-lactam in the medium, the beta-lactamase accounted for most of the resistance.

  4. Effect of decreasing electrical resistance in Characeae cell membranes caused by the flow of alternating current

    Directory of Open Access Journals (Sweden)

    Edward Śpiewla

    2014-01-01

    Full Text Available By means of the techniques of external electrodes and microelectrodes, it was found that evanescent flow of an alternating current through plasmalemma of Characeae cells neutralises oscillatory change in their electrical resistance and reversibly diminishes its value. This effect is particularly significant in the case of "high resistance cells", but it weakens with increasing temperature. The value of the estimated activation energy indicates that, after flow of the alternating current through the membrane, a rapid increase in the conductivity may be caused by an increase in conductivity of potassium channels. This result seems to support the hypothesis of electroconformational feedback.

  5. Functional Characterization of AbeD, an RND-Type Membrane Transporter in Antimicrobial Resistance in Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Vijaya Bharathi Srinivasan

    Full Text Available Acinetobacter baumannii is becoming an increasing menace in health care settings especially in the intensive care units due to its ability to withstand adverse environmental conditions and exhibit innate resistance to different classes of antibiotics. Here we describe the biological contributions of abeD, a novel membrane transporter in bacterial stress response and antimicrobial resistance in A. baumannii.The abeD mutant displayed ~ 3.37 fold decreased survival and >5-fold reduced growth in hostile osmotic (0.25 M; NaCl and oxidative (2.631 μM-6.574 μM; H2O2 stress conditions respectively. The abeD inactivated cells displayed increased susceptibility to ceftriaxone, gentamicin, rifampicin and tobramycin (~ 4.0 fold. The mutant displayed increased sensitivity to the hospital-based disinfectant benzalkonium chloride (~3.18-fold. In Caenorhabditis elegans model, the abeD mutant exhibited (P<0.01 lower virulence capability. Binding of SoxR on the regulatory fragments of abeD provide strong evidence for the involvement of SoxR system in regulating the expression of abeD in A. baumannii.This study demonstrates the contributions of membrane transporter AbeD in bacterial physiology, stress response and antimicrobial resistance in A. baumannii for the first time.

  6. Surface Ligand Density of Antibiotic-Nanoparticle Conjugates Enhances Target Avidity and Membrane Permeabilization of Vancomycin-Resistant Bacteria.

    Science.gov (United States)

    Hassan, Marwa M; Ranzoni, Andrea; Phetsang, Wanida; Blaskovich, Mark A T; Cooper, Matthew A

    2017-02-15

    Many bacterial pathogens have now acquired resistance toward commonly used antibiotics, such as the glycopeptide antibiotic vancomycin. In this study, we show that immobilization of vancomycin onto a nanometer-scale solid surface with controlled local density can potentiate antibiotic action and increase target affinity of the drug. Magnetic nanoparticles were conjugated with vancomycin and used as a model system to investigate the relationship between surface density and drug potency. We showed remarkable improvement in minimum inhibitory concentration against vancomycin-resistant strains with values of 13-28 μg/mL for conjugated vancomycin compared to 250-4000 μg/mL for unconjugated vancomycin. Higher surface densities resulted in enhanced affinity toward the bacterial target compared to that of unconjugated vancomycin, as measured by a competition experiment using a surrogate ligand for bacterial Lipid II, N-Acetyl-l-Lys-d-Ala-d-Ala. High density vancomycin nanoparticles required >64 times molar excess of ligand (relative to the vancomycin surface density) to abrogate antibacterial activity compared to only 2 molar excess for unconjugated vancomycin. Further, the drug-nanoparticle conjugates caused rapid permeabilization of the bacterial cell wall within 2 h, whereas no effect was seen with unconjugated vancomycin, suggesting additional modes of action for the nanoparticle-conjugated drug. Hence, immobilization of readily available antibiotics on nanocarriers may present a general strategy for repotentiating drugs that act on bacterial membranes or membrane-bound targets but have lost effectiveness against resistant bacterial strains.

  7. Morphologies and separation characteristics of polyphenyl sulfone-based solvent resistant nanofiltration membranes: Effect of polymer concentration in casting solution and membrane pretreatment condition

    International Nuclear Information System (INIS)

    Sani, Nur Aimie Abdullah; Lau, Woei Jye; Ismail, Ahmad Fauzi

    2015-01-01

    The performance of polyphenylsulfone (PPSU) solvent resistant nanofiltration (SRNF)-based flat sheet membranes prepared from phase inversion method was investigated by varying the concentration of polymer in the dope solution and condition of membrane pretreatment process. The membrane properties were characterized by SEM, FTIR, AFM and contact angle goniometer, while their performance was evaluated by measuring methanol flux and rejection of different molecular weight of dyes (ranging from 269 to 1,470 g/mol) in methanol. The experimental results showed that the polymer concentration has great impact not only on the final membrane morphology but also its separation characteristics. Increasing polymer concentration from 17 to 25wt% tended to suppress finger-like structure and more pear-like pores were developed, causing methanol flux to decrease. This can be explained by the decrease in molecular weight cut off (MWCO) of the membrane prepared at high polymer concentration. With respect to the effect of membrane pretreatment conditions, the rejection of membrane was negatively affected with longer immersion period in methanol solution prior to filtration experiment. The variation in membrane rejection can be attributed to the rearrangement of the polymer chain, which results in membrane swelling and/or change of membrane surface hydrophilicity

  8. Morphologies and separation characteristics of polyphenyl sulfone-based solvent resistant nanofiltration membranes: Effect of polymer concentration in casting solution and membrane pretreatment condition

    Energy Technology Data Exchange (ETDEWEB)

    Sani, Nur Aimie Abdullah; Lau, Woei Jye; Ismail, Ahmad Fauzi [Universiti Teknologi Malaysia, Skudai (Malaysia)

    2015-04-15

    The performance of polyphenylsulfone (PPSU) solvent resistant nanofiltration (SRNF)-based flat sheet membranes prepared from phase inversion method was investigated by varying the concentration of polymer in the dope solution and condition of membrane pretreatment process. The membrane properties were characterized by SEM, FTIR, AFM and contact angle goniometer, while their performance was evaluated by measuring methanol flux and rejection of different molecular weight of dyes (ranging from 269 to 1,470 g/mol) in methanol. The experimental results showed that the polymer concentration has great impact not only on the final membrane morphology but also its separation characteristics. Increasing polymer concentration from 17 to 25wt% tended to suppress finger-like structure and more pear-like pores were developed, causing methanol flux to decrease. This can be explained by the decrease in molecular weight cut off (MWCO) of the membrane prepared at high polymer concentration. With respect to the effect of membrane pretreatment conditions, the rejection of membrane was negatively affected with longer immersion period in methanol solution prior to filtration experiment. The variation in membrane rejection can be attributed to the rearrangement of the polymer chain, which results in membrane swelling and/or change of membrane surface hydrophilicity.

  9. Facile fouling resistant surface modification of microfiltration cellulose acetate membranes by using amino acid L-DOPA.

    Science.gov (United States)

    Azari, Sara; Zou, Linda; Cornelissen, Emile; Mukai, Yasushito

    2013-01-01

    A major obstacle in the widespread application of microfiltration membranes in the wet separation processes such as wastewater treatment is the decline of permeates flux as a result of fouling. This study reports on the surface modification of cellulose acetate (CA) microfiltration membrane with amino acid L-3,4-dihydroxy-phenylalanine (L-DOPA) to improve fouling resistance of the membrane. The membrane surface was characterised using Fourier transform infrared spectroscopy (FTIR), water contact angle and zeta potential measurement. Porosity measurement showed a slight decrease in membrane porosity due to coating. Static adsorption experiments revealed an improved resistance of the modified membranes towards the adhesion of bovine serum albumin (BSA) as the model foulant. Dead end membrane filtration tests exhibited that the fouling resistance of the modified membranes was improved. However, the effect of the modification depended on the foulant solution concentration. It is concluded that L-DOPA modification is a convenient and non-destructive approach to enable low-BSA adhesion surface modification of CA microfiltration membranes. Nevertheless, the extent of fouling resistance improvement depends on the foulant concentration.

  10. 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

  11. Roles of DNA repair and membrane integrity in heat resistance of Deinococcus radiodurans.

    Science.gov (United States)

    Bauermeister, Anja; Hahn, Claudia; Rettberg, Petra; Reitz, Günther; Moeller, Ralf

    2012-11-01

    To study the effects of heat shock on Deinococcus radiodurans and the role of DNA repair in high temperature resistance, different strains of D. radiodurans (wild type, recA, irrE, and pprA) were treated with temperatures ranging from 40 to 100 °C under wet and dry conditions. The mutant strains were more sensitive to wet heat of ≥60 °C and dry heat of ≥80 °C than the wild type. Both wild-type and DNA repair-deficient strains were much more resistant to high temperatures when exposed in the dried state as opposed to cells in suspension. Molecular staining techniques with the wild-type strain revealed that cells in the dried state were able to retain membrane integrity after drying and subsequent heat exposure, while heat-exposed cells in suspension showed significant loss of membrane integrity and respiration activity. The results suggest that the repair of DNA damage (e.g., DNA double-strand breaks by RecA and PprA) is essential after treatment with wet heat at temperatures >60 °C and dry heat >80 °C, and the ability of D. radiodurans to stabilize its plasma membrane during dehydration might represent one aspect in the protection of dried cells from heat-induced membrane damage.

  12. Daptomycin-resistant Enterococcus faecalis diverts the antibiotic molecule from the division septum and remodels cell membrane phospholipids.

    Science.gov (United States)

    Tran, Truc T; Panesso, Diana; Mishra, Nagendra N; Mileykovskaya, Eugenia; Guan, Ziqianq; Munita, Jose M; Reyes, Jinnethe; Diaz, Lorena; Weinstock, George M; Murray, Barbara E; Shamoo, Yousif; Dowhan, William; Bayer, Arnold S; Arias, Cesar A

    2013-07-23

    Treatment of multidrug-resistant enterococci has become a challenging clinical problem in hospitals around the world due to the lack of reliable therapeutic options. Daptomycin (DAP), a cell membrane-targeting cationic antimicrobial lipopeptide, is the only antibiotic with in vitro bactericidal activity against vancomycin-resistant enterococci (VRE). However, the clinical use of DAP against VRE is threatened by emergence of resistance during therapy, but the mechanisms leading to DAP resistance are not fully understood. The mechanism of action of DAP involves interactions with the cell membrane in a calcium-dependent manner, mainly at the level of the bacterial septum. Previously, we demonstrated that development of DAP resistance in vancomycin-resistant Enterococcus faecalis is associated with mutations in genes encoding proteins with two main functions, (i) control of the cell envelope stress response to antibiotics and antimicrobial peptides (LiaFSR system) and (ii) cell membrane phospholipid metabolism (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase). In this work, we show that these VRE can resist DAP-elicited cell membrane damage by diverting the antibiotic away from its principal target (division septum) to other distinct cell membrane regions. DAP septal diversion by DAP-resistant E. faecalis is mediated by initial redistribution of cell membrane cardiolipin-rich microdomains associated with a single amino acid deletion within the transmembrane protein LiaF (a member of a three-component regulatory system [LiaFSR] involved in cell envelope homeostasis). Full expression of DAP resistance requires additional mutations in enzymes (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase) that alter cell membrane phospholipid content. Our findings describe a novel mechanism of bacterial resistance to cationic antimicrobial peptides. The emergence of antibiotic resistance in bacterial pathogens is a threat to public health

  13. Nano-ZnO embedded mixed matrix polyethersulfone (PES) membrane: Influence of nanofiller shape on characterization and fouling resistance

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, Hamid [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Department of Civil Engineering, Razi University, 67149 Kermanshah (Iran, Islamic Republic of); Ghaemi, Negin, E-mail: negin_ghaemi@kut.ac.ir [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Madaeni, Sayed S. [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Daraei, Parisa [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Astinchap, Bandar [Physics Department, Faculty of Science, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Zinadini, Sirus [Water and Wastewater Research Center (WWRC), Department of Applied Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Razavizadeh, Sayed Hossein [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of)

    2015-09-15

    Graphical abstract: - Highlights: • ZnO nanofillers with different shape (nanorod and nanoparticle) were synthesized. • Mixed matrix PES membranes were fabricated by different concentrations of nanofillers. • Embedding nanofillers affected on morphology and hydrophilicity of PES membranes. • Nanorod MM membranes revealed the highest water flux and antifouling characteristic. • ZnO nanorod-embedded membrane showed an acceptable reusability and durability. - Abstract: Two different kinds of nano-ZnO (nanoparticle and nanorod) were synthesized, characterized, and embedded in a PES membrane matrix to investigate the effects of a nanofiller shape on the mixed matrix membrane characteristics and the antifouling capability. The mixed matrix membranes were fabricated by mixing different amounts of nanofillers with dope solution followed by a phase inversion precipitation technique. The effect of the shape of the embedded nanofillers on the morphology and performance of the fabricated membranes was studied in terms of pure water flux, fouling resistance, hydrophilicity, surface, and bulk morphology by means of permeation tests, milk powder solution filtration, water contact angle and porosity measurements, scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques. Water flux of the mixed matrix membranes significantly improved after the addition of both types of ZnO nanofillers due to a higher hydrophilicity and porosity of the prepared membranes. The water contact angle measurements confirmed the increased hydrophilicity of the modified membranes, particularly in the ZnO nanorod mixed membranes. Fouling resistance of the membranes assessed by powder milk solution filtration revealed that 0.1 wt% ZnO nanorod membrane has the best antifouling property. The prepared mixed matrix membranes embedded with 0.1 wt% of both types of ZnO nanofillers showed a remarkable durability and reusability during the filtration tests; however, the best

  14. The Mechanism by Which Luteolin Disrupts the Cytoplasmic Membrane of Methicillin-Resistant Staphylococcus aureus.

    Science.gov (United States)

    Zhang, Tao; Qiu, Yunguang; Luo, Qichao; Zhao, Lifen; Yan, Xin; Ding, Qiaoce; Jiang, Hualiang; Yang, Huaiyu

    2018-02-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most versatile human pathogens. Luteolin (LUT) has anti-MRSA activity by disrupting the MRSA cytoplasmic membrane. However, the mechanism by which luteolin disrupts the membrane remains unclear. Here, we performed differential scanning calorimetry (DSC) and all-atomic molecular dynamics (AA-MD) simulations to investigate the interactions and effects of LUT on model membranes composed of phosphatidylcholine (PC) and phosphatidylglycerol (PG). We detected the transition thermodynamic parameters of dipalmitoylphosphatidylcholine (DPPC) liposomes, dipalmitoylphosphatidylglycerol (DPPG) liposomes, and liposomes composed of both DPPC and DPPG at different LUT concentrations and showed that LUT molecules were located between polar heads and the hydrophobic region of DPPC/DPPG. In the MD trajectories, LUT molecules ranging from 5 to 50 had different effects on the membranes thickness, fluidity and ordered property of lipids, and lateral pressure of lipid bilayers composed of dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylglycerol (DOPG). Also, most LUT molecules were distributed in the region between the phosphorus atoms and C9 atoms of DOPC and DOPG. On the basis of the combination of these results, we conclude that the distinct effects of LUT on lipid bilayers composed of PCs and PGs may elucidate the mechanism by which LUT disrupts the cytoplasmic membrane of MRSA.

  15. 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.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    experiments showed that the membrane-sensor was suitable as a cell culturing substrate for bio-applications. Real-time measurements of dopamine exocytosis in cell cultures were performed, where the transmitter release was recorded at the point of release. The developed membrane-sensor provides a new......This article presents a novel membrane-based sensor for real-time electrochemical investigations of cellular- or tissue cultures. The membrane sensor enables recording of electrical signals from a cell culture without any signal dilution, thus avoiding loss of sensitivity. Moreover, the porosity...

  17. Effect of evaporation time on cellulose acetate membrane for gas separation

    Science.gov (United States)

    Jami'an, W. N. R.; Hasbullah, H.; Mohamed, F.; Yusof, N.; Ibrahim, N.; Ali, R. R.

    2016-06-01

    Throughout this decades, membrane technology has been the desirable option among the others gas separation technologies. However, few issues have been raised regarding the membrane gas separation application including the trade-off between its permeability and selectivity and also its effects towards environment. Therefore, for this research, a biopolymer membrane for gas separation application will be developed with reasonably high on both permeability and selectivity. The main objective of this research is to study the effect of solvent evaporation time on the flat sheet asymmetric membrane morphology and gas separation performance. The membranes were produced by a simple dry/wet phase inversion technique using a pneumatically controlled casting system. The dope solution for the membrane casting was prepared by dissolving the cellulose acetate (CA) polymer in N-Methyl-2-pyrrolidone (NMP) and the solvent evaporation time was varied. Permeability and selectivity of the membrane was performed by using pure gases of carbon dioxide, CO2 and methane, CH4. The increase in solvent evaporation time had improved the membrane morphologies as the porosity of the membrane surface decrease and formation of a more mature skin layer. The gas permeation tests determined that increasing in solvent evaporation time had increased the selectivity of CO2/CH4 but reduce the permeability of both gases

  18. Identification and network of outer membrane proteins regulating streptomysin resistance in Escherichia coli.

    Science.gov (United States)

    Li, Hui; Wang, Bao-Cheng; Xu, Wen-Jiao; Lin, Xiang-Min; Peng, Xuan-Xian

    2008-09-01

    Bacterial Outer membrane (OM) proteins involved in antibiotic resistance have been reported. However, little is known about the OM proteins and their interaction network regulating streptomycin (SM) resistance. In the present study, a subproteomic approach was utilized to characterize OM proteins of Escherichia coli with SM resistance. TolC, OmpT and LamB were found to be up-regulated, and FadL, OmpW and a location-unknown protein Dps were down-regulated in the SM-resistant E. coli strain. These changes at the level of protein expression were validated using Western blotting. The possible roles of the altered proteins involved in the SM resistance were investigated using genetic modified strains with the deletion of these altered genes. It is found that decreased and elevated minimum inhibitory concentrations and survival capabilities of the gene deleted strains and their resistant strains, Delta tolC, Delta ompT, Delta dps, Delta tolC-R, Delta ompT-R, Delta dps-R and Delta fadL-R, were correlated with the changes of TolC, OmpT, Dps and FadL at the protein expression levels detected by 2-DE gels, respectively. The results may suggest that these proteins are the key OM proteins and play important roles in the regulation of SM resistance in E. coli. Furthermore, an interaction network of altered OM proteins involved in the SM resistance was proposed in this report. Of the six altered proteins, TolC may play a central role in the network. These findings may provide novel insights into mechanisms of SM resistance in E. coli.

  19. Involvement of outer membrane proteins and peroxide-sensor genes in Burkholderia cepacia resistance to isothiazolone.

    Science.gov (United States)

    Zhou, Gang; Shi, Qing-shan; Ouyang, You-sheng; Chen, Yi-ben

    2014-04-01

    Isothiazolones are used as preservatives in various modern industrial products. Although microorganisms that exhibit resistance towards these biocides have been identified, the underlying resistance mechanisms are still unclear. Therefore, we investigated the resistance properties of the following Burkholderia cepacia strains to Kathon (a representative of isothiazolones): a wild-type (WT) strain; a laboratory resistance strain (BC-IR) induced from WT; and an isolated strain (BC-327) screened from industrial contamination samples. The bacterial cell structure was disrupted by 50 μg ml⁻¹ Kathon treatment. BC-IR and BC-327 did not display resistance in the presence of 1 ml L⁻¹ Tween 80, 1 ml L⁻¹ Triton X-100, 0.1 % sodium dodecyl sulfate or 1 mmol L⁻¹ EDTA-2Na. Additionally, BC-IR and BC-327 exhibited lower relative conductivity from 10 to 180 min. The types as well as the levels of outer-membrane proteins (OMPs) were altered among WT, BC-IR and BC-327. Finally, the two Kathon-resistance strains BC-IR and BC-327 presented higher resistance capacity to H₂O₂. We measured the levels of peroxide-sensor genes and observed that the transcriptional activator oxyR, superoxide dismutase sod1, sod2, catalase cat1 and cat3 were all up-regulated under oxidative conditions for all strains. Taken together, OMPs and peroxide-sensor genes in B. cepacia contributed to isothiazolone resistance; However, the laboratory strain BC-IR exhibited a different resistance mechanism and properties compared to the isolated strain BC-327.

  20. Adaptation of Pseudomonas aeruginosa ATCC 15442 to didecyldimethylammonium bromide induces changes in membrane fatty acid composition and in resistance of cells.

    Science.gov (United States)

    Méchin, L; Dubois-Brissonnet, F; Heyd, B; Leveau, J Y

    1999-05-01

    The role of membrane fatty acid composition in the resistance of Pseudomonas aeruginosa ATCC 15442 to the bactericidal activity of didecyldimethyl ammonium bromide (DDAB) was investigated. In this study, the strain was sub-cultured in a medium with increasing DDAB concentrations. After adaptation, Ps. aeruginosa was able to grow until the DDAB concentration in the medium was about five times greater than the Minimal Inhibitory Concentration. Resistance of cells to the bactericidal activity of DDAB also increased gradually during adaptation. This resistance was dependent on the presence of the biocide, as it quickly decreased when the cells were transferred to medium without biocide. Adapted cells showed changes in membrane fatty acid composition. The modifications mainly affected lauric, beta-hydroxylauric and palmitic acids, and they underlined the implication of the membranes in the cell response to the presence of the biocide. Simple linear regression analysis showed that the membrane fatty acid composition of Ps. aeruginosa played an important part in the resistance mechanisms of cells to the bactericidal activity of DDAB.

  1. Intracellular and membrane-damaging activities of methyl gallate isolated from Terminalia chebula against multidrug-resistant Shigella spp.

    Science.gov (United States)

    Acharyya, Saurabh; Sarkar, Prodipta; Saha, Dhira R; Patra, Amarendra; Ramamurthy, T; Bag, Prasanta K

    2015-08-01

    Shigella spp. (Shigella dysenteriae, Shigella flexneri, Shigella boydii and Shigella sonnei) cause bacillary dysentery (shigellosis), which is characterized by bloody mucous diarrhoea. Although a variety of antibiotics have been effective for treatment of shigellosis, options are becoming limited due to globally emerging drug resistance. In the present study, in vitro antibacterial activity of methyl gallate (MG) isolated from Terminalia chebula was determined by performing MIC, minimal bactericidal concentration (MBC) and time-kill kinetic studies. Bacterial membrane-damaging activity of MG was determined by membrane perturbation and transmission electron microscopy (TEM). Cellular drug accumulation, cell infection and assessment of intracellular activities of MG and reference antibiotics were performed using HeLa cell cultures. The bactericidal activity of MG against multidrug-resistant (MDR) Shigella spp. in comparison with other commonly used drugs including fluoroquinolone was demonstrated here. TEM findings in the present study revealed that MG caused the total disintegration of inner and outer membranes, and leakage of the cytoplasmic contents of S. dysenteriae. The level of accumulation of MG and tetracycline in HeLa cells incubated for 24  h was relatively higher than that of ciprofloxacin and nalidixic acid (ratio of intracellular concentration/extracellular concentration of antibiotic for MG and tetracycline>ciprofloxacin and nalidixic acid). The viable number of intracellular S. dysenteriae was decreased in a time-dependent manner in the presence of MG (4 × MBC) and reduced to zero within 20  h. The significant intracellular activities of MG suggested that it could potentially be used as an effective antibacterial agent for the treatment of severe infections caused by MDR Shigella spp.

  2. Rapid preparation of nuclei-depleted detergent-resistant membrane fractions suitable for proteomics analysis

    Directory of Open Access Journals (Sweden)

    Mukhopadhyay Nishit K

    2008-06-01

    Full Text Available Abstract Background Cholesterol-rich membrane microdomains known as lipid rafts have been implicated in diverse physiologic processes including lipid transport and signal transduction. Lipid rafts were originally defined as detergent-resistant membranes (DRMs due to their relative insolubility in cold non-ionic detergents. Recent findings suggest that, although DRMs are not equivalent to lipid rafts, the presence of a given protein within DRMs strongly suggests its potential for raft association in vivo. Therefore, isolation of DRMs represents a useful starting point for biochemical analysis of lipid rafts. The physicochemical properties of DRMs present unique challenges to analysis of their protein composition. Existing methods of isolating DRM-enriched fractions involve flotation of cell extracts in a sucrose density gradient, which, although successful, can be labor intensive, time consuming and results in dilute sucrose-containing fractions with limited utility for direct proteomic analysis. In addition, several studies describing the proteomic characterization of DRMs using this and other approaches have reported the presence of nuclear proteins in such fractions. It is unclear whether these results reflect trafficking of nuclear proteins to DRMs or whether they arise from nuclear contamination during isolation. To address these issues, we have modified a published differential detergent extraction method to enable rapid DRM isolation that minimizes nuclear contamination and yields fractions compatible with mass spectrometry. Results DRM-enriched fractions isolated using the conventional or modified extraction methods displayed comparable profiles of known DRM-associated proteins, including flotillins, GPI-anchored proteins and heterotrimeric G-protein subunits. Thus, the modified procedure yielded fractions consistent with those isolated by existing methods. However, we observed a marked reduction in the percentage of nuclear proteins

  3. Assessment of Membrane Fluidity Fluctuations during Cellular Development Reveals Time and Cell Type Specificity

    KAUST Repository

    Noutsi, Pakiza

    2016-06-30

    Cell membrane is made up of a complex structure of lipids and proteins that diffuse laterally giving rise to what we call membrane fluidity. During cellular development, such as differentiation cell membranes undergo dramatic fluidity changes induced by proteins such as ARC and Cofilin among others. In this study we used the generalized polarization (GP) property of fluorescent probe Laurdan using two-photon microscopy to determine membrane fluidity as a function of time and for various cell lines. A low GP value corresponds to a higher fluidity and a higher GP value is associated with a more rigid membrane. Four different cell lines were monitored such as hN2, NIH3T3, HEK293 and L6 cells. Membrane fluidity was measured at 12h, 72h and 92 h. Our results show significant changes in membrane fluidity among all cell types at different time points. GP values tend to increase significantly within 92 h in hN2 cells and 72 h in NIH3T3 cells and only at 92 h in HEK293 cells. L6 showed a marked decrease in membrane fluidity at 72 h and starts to increase at 92 h. As expected, NIH3T3 cells have more rigid membrane at earlier time points. On the other hand, neurons tend to have the highest membrane fluidity at early time points emphasizing its correlation with plasticity and the need for this malleability during differentiation. This study sheds light on the involvement of membrane fluidity during neuronal differentiation and development of other cell lines.

  4. Handling Time-dependent Variables : Antibiotics and Antibiotic Resistance

    NARCIS (Netherlands)

    Munoz-Price, L. Silvia; Frencken, Jos F.; Tarima, Sergey; Bonten, Marc

    2016-01-01

    Elucidating quantitative associations between antibiotic exposure and antibiotic resistance development is important. In the absence of randomized trials, observational studies are the next best alternative to derive such estimates. Yet, as antibiotics are prescribed for varying time periods,

  5. ABCA1, ABCG1, and ABCG4 are distributed to distinct membrane meso-domains and disturb detergent-resistant domains on the plasma membrane.

    Directory of Open Access Journals (Sweden)

    Osamu Sano

    Full Text Available ATP-binding cassette A1 (ABCA1, ABCG1, and ABCG4 are lipid transporters that mediate the efflux of cholesterol from cells. To analyze the characteristics of these lipid transporters, we examined and compared their distributions and lipid efflux activity on the plasma membrane. The efflux of cholesterol mediated by ABCA1 and ABCG1, but not ABCG4, was affected by a reduction of cellular sphingomyelin levels. Detergent solubility and gradient density ultracentrifugation assays indicated that ABCA1, ABCG1, and ABCG4 were distributed to domains that were solubilized by Triton X-100 and Brij 96, resistant to Triton X-100 and Brij 96, and solubilized by Triton X-100 but resistant to Brij 96, respectively. Furthermore, ABCG1, but not ABCG4, was colocalized with flotillin-1 on the plasma membrane. The amounts of cholesterol extracted by methyl-β-cyclodextrin were increased by ABCA1, ABCG1, or ABCG4, suggesting that cholesterol in non-raft domains was increased. Furthermore, ABCG1 and ABCG4 disturbed the localization of caveolin-1 to the detergent-resistant domains and the binding of cholera toxin subunit B to the plasma membrane. These results suggest that ABCA1, ABCG1, and ABCG4 are localized to distinct membrane meso-domains and disturb the meso-domain structures by reorganizing lipids on the plasma membrane; collectively, these observations may explain the different substrate profiles and lipid efflux roles of these transporters.

  6. Mechanism of HIV-1 Resistance to an Electronically Constrained α-Helical Peptide Membrane Fusion Inhibitor.

    Science.gov (United States)

    Wu, Xiyuan; Liu, Zixuan; Ding, Xiaohui; Yu, Danwei; Wei, Huamian; Qin, Bo; Zhu, Yuanmei; Chong, Huihui; Cui, Sheng; He, Yuxian

    2018-04-01

    SC29EK is an electronically constrained α-helical peptide HIV-1 fusion inhibitor that is highly effective against both wild-type and enfuvirtide (T20)-resistant viruses. In this study, we focused on investigating the mechanism of HIV-1 resistance to SC29EK by two approaches. First, SC29EK-escaping HIV-1 variants were selected and characterized. Three mutant viruses, which possessed two (N43K/E49A) or three (Q39R/N43K/N126K and N43K/E49A/N126K) amino acid substitutions in the N- and C-terminal repeat regions of gp41 were identified as conferring high resistance to SC29EK and cross-resistance to the first-generation (T20 and C34) and newly designed (sifuvirtide, MT-SC29EK, and 2P23) fusion inhibitors. The resistance mutations could reduce the binding stability of SC29EK, impair viral Env-mediated cell fusion and entry, and change the conformation of the gp41 core structure. Further, we determined the crystal structure of SC29EK in complex with a target mimic peptide, which revealed the critical intra- and interhelical interactions underlying the mode of action of SC29EK and the genetic pathway to HIV-1 resistance. Taken together, the present data provide new insights into the structure and function of gp41 and the structure-activity relationship (SAR) of viral fusion inhibitors. IMPORTANCE T20 is the only membrane fusion inhibitor available for treatment of viral infection, but it has relatively low anti-HIV activity and genetic barriers for resistance, thus calling for new drugs blocking the viral fusion process. As an electronically constrained α-helical peptide, SC29EK is highly potent against both wild-type and T20-resistant HIV-1 strains. Here, we report the characterization of HIV-1 variants resistant to SC29EK and the crystal structure of SC29EK. The key mutations mediating high resistance to SC29EK and cross-resistance to the first and new generations of fusion inhibitors as well as the underlying mechanisms were identified. The crystal structure of SC29EK

  7. Effect of growth temperature, surface type and incubation time on the resistance of Staphylococcus aureus biofilms to disinfectants.

    Science.gov (United States)

    Abdallah, Marwan; Chataigne, Gabrielle; Ferreira-Theret, Pauline; Benoliel, Corinne; Drider, Djamel; Dhulster, Pascal; Chihib, Nour-Eddine

    2014-03-01

    The goal of this study was to investigate the effect of the environmental conditions such as the temperature change, incubation time and surface type on the resistance of Staphylococcus aureus biofilms to disinfectants. The antibiofilm assays were performed against biofilms grown at 20 °C, 30 °C and 37 °C, on the stainless steel and polycarbonate, during 24 and 48 h. The involvement of the biofilm matrix and the bacterial membrane fluidity in the resistance of sessile cells were investigated. Our results show that the efficiency of disinfectants was dependent on the growth temperature, the surface type and the disinfectant product. The increase of growth temperature from 20 °C to 37 °C, with an incubation time of 24 h, increased the resistance of biofilms to cationic antimicrobials. This change of growth temperature did not affect the major content of the biofilm matrix, but it decreased the membrane fluidity of sessile cells through the increase of the anteiso-C19 relative amount. The increase of the biofilm resistance to disinfectants, with the rise of the incubation time, was dependent on both growth temperature and disinfectant product. The increase of the biofilm age also promoted increases in the matrix production and the membrane fluidity of sessile cells. The resistance of S. aureus biofilm seems to depend on the environment of the biofilm formation and involves both extracellular matrix and membrane fluidity of sessile cells. Our study represents the first report describing the impact of environmental conditions on the matrix production, sessile cells membrane fluidity and resistance of S. aureus biofilms to disinfectants.

  8. Fluorescence interference contrast based approach to study real time interaction of melittin with plasma membranes

    Science.gov (United States)

    Gupta, Sharad; Gui, Dong; Zandi, Roya; Gill, Sarjeet; Mohideen, Umar

    2014-03-01

    Melittin is an anti-bacterial and hemolytic toxic peptide found in bee venom. Cell lysis behavior of peptides has been widely investigated, but the exact interaction mechanism of lytic peptides with lipid membranes and its constituents has not been understood completely. In this paper we study the melittin interaction with lipid plasma membranes in real time using non-invasive and non-contact fluorescence interference contrast microscopy (FLIC). Particularly the interaction of melittin with plasma membranes was studied in a controlled molecular environment, where these plasma membrane were composed of saturated lipid, 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) and unsaturated lipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine(DOPC) with and without cholesterol. We found out that melittin starts to form nanometer size pores in the plasma membranes shortly after interacting with membranes. But the addition of cholesterol in plasma membrane slows down the pore formation process. Our results show that inclusion of cholesterol to the plasma membranes make them more resilient towards pore formation and lysis of membrane.

  9. A compensatory mutation provides resistance to disparate HIV fusion inhibitor peptides and enhances membrane fusion.

    Directory of Open Access Journals (Sweden)

    Matthew P Wood

    Full Text Available Fusion inhibitors are a class of antiretroviral drugs used to prevent entry of HIV into host cells. Many of the fusion inhibitors being developed, including the drug enfuvirtide, are peptides designed to competitively inhibit the viral fusion protein gp41. With the emergence of drug resistance, there is an increased need for effective and unique alternatives within this class of antivirals. One such alternative is a class of cyclic, cationic, antimicrobial peptides known as θ-defensins, which are produced by many non-human primates and exhibit broad-spectrum antiviral and antibacterial activity. Currently, the θ-defensin analog RC-101 is being developed as a microbicide due to its specific antiviral activity, lack of toxicity to cells and tissues, and safety in animals. Understanding potential RC-101 resistance, and how resistance to other fusion inhibitors affects RC-101 susceptibility, is critical for future development. In previous studies, we identified a mutant, R5-tropic virus that had evolved partial resistance to RC-101 during in vitro selection. Here, we report that a secondary mutation in gp41 was found to restore replicative fitness, membrane fusion, and the rate of viral entry, which were compromised by an initial mutation providing partial RC-101 resistance. Interestingly, we show that RC-101 is effective against two enfuvirtide-resistant mutants, demonstrating the clinical importance of RC-101 as a unique fusion inhibitor. These findings both expand our understanding of HIV drug-resistance to diverse peptide fusion inhibitors and emphasize the significance of compensatory gp41 mutations.

  10. Novel Membrane-Based Electrochemical Sensor for Real-Time Bio-Applications

    Directory of Open Access Journals (Sweden)

    Fatima AlZahra'a Alatraktchi

    2014-11-01

    Full Text Available This article presents a novel membrane-based sensor for real-time electrochemical investigations of cellular- or tissue cultures. The membrane sensor enables recording of electrical signals from a cell culture without any signal dilution, thus avoiding loss of sensitivity. Moreover, the porosity of the membrane provides optimal culturing conditions similar to existing culturing techniques allowing more efficient nutrient uptake and molecule release. The patterned sensor electrodes were fabricated on a porous membrane by electron-beam evaporation. The electrochemical performance of the membrane electrodes was characterized by cyclic voltammetry and chronoamperometry, and the detection of synthetic dopamine was demonstrated down to a concentration of 3.1 pM. Furthermore, to present the membrane-sensor functionality the dopamine release from cultured PC12 cells was successfully measured. The PC12 cells culturing experiments showed that the membrane-sensor was suitable as a cell culturing substrate for bio-applications. Real-time measurements of dopamine exocytosis in cell cultures were performed, where the transmitter release was recorded at the point of release. The developed membrane-sensor provides a new functionality to the standard culturing methods, enabling sensitive continuous in vitro monitoring and closely mimicking the in vivo conditions.

  11. Daptomycin resistance in enterococci is associated with distinct alterations of cell membrane phospholipid content.

    Directory of Open Access Journals (Sweden)

    Nagendra N Mishra

    Full Text Available The lipopeptide antibiotic, daptomycin (DAP interacts with the bacterial cell membrane (CM. Development of DAP resistance during therapy in a clinical strain of Enterococcus faecalis was associated with mutations in genes encoding enzymes involved in cell envelope homeostasis and phospholipid metabolism. Here we characterized changes in CM phospholipid profiles associated with development of DAP resistance in clinical enterococcal strains.Using two clinical strain-pairs of DAP-susceptible and DAP-resistant E. faecalis (S613 vs. R712 and E. faecium (S447 vs. R446 recovered before and after DAP therapy, we compared four distinct CM profiles: phospholipid content, fatty acid composition, membrane fluidity and capacity to be permeabilized and/or depolarized by DAP. Additionally, we characterized the cell envelope of the E. faecium strain-pair by transmission electron microscopy and determined the relative cell surface charge of both strain-pairs.Both E. faecalis and E. faecium mainly contained four major CM PLs: phosphatidylglycerol (PG, cardiolipin, lysyl-phosphatidylglycerol (L-PG and glycerolphospho-diglycodiacylglycerol (GP-DGDAG. In addition, E. faecalis CMs (but not E. faecium also contained: i phosphatidic acid; and ii two other unknown species of amino-containing PLs. Development of DAP resistance in both enterococcal species was associated with a significant decrease in CM fluidity and PG content, with a concomitant increase in GP-DGDAG. The strain-pairs did not differ in their outer CM translocation (flipping of amino-containing PLs. Fatty acid content did not change in the E. faecalis strain-pair, whereas a significant decrease in unsaturated fatty acids was observed in the DAP-resistant E. faecium isolate R446 (vs S447. Resistance to DAP in E. faecium was associated with distinct structural alterations of the cell envelope and cell wall thickening, as well as a decreased ability of DAP to depolarize and permeabilize the CM

  12. ISOELECTRIC FOCUSING OF MEMBRANE PROTEINS OF PROBIOTIC B. COAGULANS AND ITS BACTERIOPHAGE RESISTANT MUTANTS

    Directory of Open Access Journals (Sweden)

    Kavita Rajesh Pandey

    2016-09-01

    Full Text Available Bacteriophages are the most notorious type of infection in the probiotic and dairy fermentations. Two phage resistant mutants viz. B. co PIII and B. co MIII (B. coagulans mutants PIII and MIII obtained in previous studies (Dubey and Vakil, 2010, were further characterized for their protein profile in comparison with the parental probiotic strain –B. coagulans. The cell lysates were subjected to ultra-centrifugation and the purified membrane fractions were resolved using 2D gel electrophoresis. The Isoelectric focussing showed 187, 202 and 154 protein spots for the parental strain, mutant B. co PIII and mutant B. co MIII, respectively. Ten and 18 protein spots were missing as compared to parent for mutants B.co PIII and B.co MIII whereas there were 21 and 14 new spots noticed for these two mutants. Eight membrane proteins present only in the phage sensitive parental culture could be tentatively identified by comparison with the complete proteome of B. coagulans by use of UniprotKB and then CELLO database It is quite likely that some of these identified membrane proteins may be also functioning as receptors for phage adsorption followed by entry of nucleic acid into the phage sensitive host cell.

  13. Long-Time Plasma Membrane Imaging Based on a Two-Step Synergistic Cell Surface Modification Strategy.

    Science.gov (United States)

    Jia, Hao-Ran; Wang, Hong-Yin; Yu, Zhi-Wu; Chen, Zhan; Wu, Fu-Gen

    2016-03-16

    Long-time stable plasma membrane imaging is difficult due to the fast cellular internalization of fluorescent dyes and the quick detachment of the dyes from the membrane. In this study, we developed a two-step synergistic cell surface modification and labeling strategy to realize long-time plasma membrane imaging. Initially, a multisite plasma membrane anchoring reagent, glycol chitosan-10% PEG2000 cholesterol-10% biotin (abbreviated as "GC-Chol-Biotin"), was incubated with cells to modify the plasma membranes with biotin groups with the assistance of the membrane anchoring ability of cholesterol moieties. Fluorescein isothiocyanate (FITC)-conjugated avidin was then introduced to achieve the fluorescence-labeled plasma membranes based on the supramolecular recognition between biotin and avidin. This strategy achieved stable plasma membrane imaging for up to 8 h without substantial internalization of the dyes, and avoided the quick fluorescence loss caused by the detachment of dyes from plasma membranes. We have also demonstrated that the imaging performance of our staining strategy far surpassed that of current commercial plasma membrane imaging reagents such as DiD and CellMask. Furthermore, the photodynamic damage of plasma membranes caused by a photosensitizer, Chlorin e6 (Ce6), was tracked in real time for 5 h during continuous laser irradiation. Plasma membrane behaviors including cell shrinkage, membrane blebbing, and plasma membrane vesiculation could be dynamically recorded. Therefore, the imaging strategy developed in this work may provide a novel platform to investigate plasma membrane behaviors over a relatively long time period.

  14. Activity of tick antimicrobial peptide from Ixodes persulcatus (persulcatusin) against cell membranes of drug-resistant Staphylococcus aureus.

    Science.gov (United States)

    Miyoshi, Naruhide; Isogai, Emiko; Hiramatsu, Keiichi; Sasaki, Takashi

    2017-02-01

    Persulcatusin (IP), which is an antimicrobial peptide found in Ixodes persulcatus midgut, is active against Gram-positive bacteria such as Staphylococcus aureus. Multidrug-resistant bacteria in particular methicillin-resistant S. aureus (MRSA), vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) are a worldwide clinical concern. In the present study, to explore the potential of IP as a new agent against multidrug-resistant S. aureus infections, we evaluated the antimicrobial activity of IP against multidrug-resistant S. aureus strains by MIC 90 , morphological observation with scanning electron microscope (SEM), and the calcein leakage assay of membrane integrity. Among the six antimicrobial peptides used in this study, IP exhibited the lowest MIC 90 values for both vancomycin-susceptible and -resistant S. aureus strains. The IP MIC 90 against a VISA strain was equivalent to vancomycin, while the MIC 90 against VRSA was relatively low. SEM observations indicated that bacterial cells exposed to IP were crumpled and showed prominent structural changes. Moreover, IP influenced the cell membranes of both MRSA and VRSA in a mere 5 min, leading to leakage of the preloaded calcein. Although a VISA strain was resistant to the action of IP on cell membrane, the MIC 90 of IP was lower than that of Nisin, suggesting that IP had another bactericidal mechanism in addition to cell membrane attack. Our results indicate that the synthetic tick antimicrobial peptide, IP exhibits strong antibacterial activity against multidrug-resistant S. aureus strains, including VRSA, via both cell membrane attack and another unknown mechanism. IP represents a promising candidate for a new anti-VRSA therapy.

  15. Influence of hydraulic retention time on UASB post-treatment with UF membranes.

    Science.gov (United States)

    Salazar-Peláez, M L; Morgan-Sagastume, J M; Noyola, A

    2011-01-01

    A pilot UASB reactor coupled with an external ultrafiltration (UF) membrane was operated under three different hydraulic retention times (HRT) for domestic wastewater treatment. The aim was to assess the HRT influence on system performance and fouling. The highest concentrations of COD, total solids, extracellular polymeric substances (EPS) and soluble microbial products (SMP) in UASB effluent and permeate were found when the UASB reactor was operated under the lowest HRT studied (4 hours); although the fulfillment of Mexican Standard for wastewater reclamation was not compromised. This fact could be attributed to the higher shear stress forces inside the UASB reactor when it was operated at low HRT, which promoted the release of biopolymeric substances in its effluent. Besides, the fouling propensity in the UASB effluent was worsened with HRT reduction, by increasing the fouling rate and the specific cake resistance. Based on these results, it is recommended to avoid operating the UASB reactor at low HRTs (less than 4 hours) in order to control SMP and EPS fouling potential. The results presented also suggest that HRT reduction has a detrimental effect on performance and fouling.

  16. High-Melting Lipid Mixtures and the Origin of Detergent-Resistant Membranes Studied with Temperature-Solubilization Diagrams

    OpenAIRE

    Sot, Jesús; Manni, Marco M.; Viguera, Ana R.; Castañeda, Verónica; Cano, Ainara; Alonso, Cristina; Gil, David; Valle, Mikel; Alonso, Alicia; Goñi, Félix M.

    2014-01-01

    The origin of resistance to detergent solubilization in certain membranes, or membrane components, is not clearly understood. We have studied the solubilization by Triton X-100 of binary mixtures composed of egg sphingomyelin (SM) and either ceramide, diacylglycerol, or cholesterol. Solubilization has been assayed in the 4–50°C range, and the results are summarized in a novel, to our knowledge, form of plots, that we have called temperature-solubilization diagrams. Despite using a large deter...

  17. Connecting membrane fluidity and surface charge to pore-forming antimicrobial peptides resistance by an ANN-based predictive model.

    Science.gov (United States)

    Mehla, Jitender; Sood, S K

    2013-05-01

    Efficiency of antibacterial chemotherapy is gradually more challenged by the emergence of pathogenic strains exhibiting high levels of antibiotic resistance. Pore-forming antimicrobial peptides (PF-AMPs) such as alamethicin (Alm) are therefore in the focus of extensive research efforts. In the present study, an artificial neural network (ANN)-based quantitative structure-activity relationship (SAR) modeling of membrane phospholipids vs. PF-AMPs, in context to membrane fluidity and surface charge, was carried out. We observed that the potency of PF-AMPs depends on the fatty acyl chain and polar head group of phospholipids. Alm showed surface interactions with zwitterionic phospholipids however could penetrate deeper inside the hydrophobic core of anionic membranes. Here, the resistance developed in bacterial cells was coupled to membrane fluidity and surface charge, and simultaneously, these principles could be applied for combating resistance against PF-AMPs. The correlation coefficient between observed CR and predicted CR using ANN was found to be 0.757. Thus, ANN could be used as a reliable modeling method for predicting CR, given the structure of the biomimetic membrane in terms of membrane fluidity and surface charge. Fully explored mechanisms of resistance, a forward modeling step in the design cycle of AMPs, can be cross-linked to the inward modeling using ANN to complete the peptide design cycle. The SAR between membrane phospholipids and PF-AMPs could furnish valuable information regarding their design to provide us efficacious peptides against premier pathogens. So far, this is the only report available to predict and quantify interactions of PF-AMPs with membrane phospholipids.

  18. Resistivity in Play-Doh: Time and Color Variations

    Science.gov (United States)

    Fuse, Christopher; August, Brandon; Cannaday, Ashley; Barker, Casey

    2013-09-01

    The study of electricity and magnetism is fundamental to all first-year physics courses. Developing simple electricity laboratory experiences that are open ended and inquiry based can be difficult. We wished to create a lab experiment where the students have some control over the experimental design, data analysis is required, and students investigate the concept of resistivity as found in Halliday Resnick, and Walker. This experiment uses modeling clay or Play-Doh™ to demonstrate the properties of ohmic materials and resistivity. We were familiar with the paper "Resistance Measurements on Play-Doh™" by Jones2 and we have worked to more accurately explain the physics of the experiment. We have also further developed the experiment to better understand how the resistivity of Play-Doh changes with time. This lab is an exciting, fun experiment that connects a new concept with a familiar childhood toy.

  19. Sugarcane vinasse treatment by two-stage anaerobic membrane bioreactor: Effect of hydraulic retention time on changes in efficiency, biogas production and membrane fouling.

    Science.gov (United States)

    Santos, Fábio S; Ricci, Bárbara C; França Neta, Luzia S; Amaral, Míriam C S

    2017-12-01

    This research investigated the effect of hydraulic retention time (HRT) on two-stage anaerobic membrane bioreactor (2-SAnMBR) performance treating sugarcane vinasse. The experimental setup consisted of an upflow acidogenic reactor and a continuous stirred methanogenic reactor, fitted with submersed microfiltration hollow-fiber membranes. The results indicated excellent performance and robustness of 2-SAnMBR. The reduction in HRT of 5.3-3.1days did not cause loss of its performance. The 2-SAnMBR showed high capacity of removing organic matter (97%), producing biogas (6.3Nm 3 of CH 4 per m 3 of treated vinasse) and did not completely remove important nutrients to fertigation. Reducing the HRT, the average mass of soluble microbial products (SMP) and extracellular polymeric substances (EPS) per mass of mixed liquor volatile suspended solids (MLVSS) increased. Consequently, the transmembrane pressure (TPM) rate and fouling resistance rise. Despite the fouling effect, physical and chemical cleaning processes were able to recover operational permeability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Plasticization-resistant hollow fiber membranes for CO2/CH4 separation based on a thermally crosslinkable polyimide

    KAUST Repository

    Chen, Chien-Chiang

    2011-10-01

    Decarboxylation-induced thermal crosslinking has been demonstrated to be effective for stabilizing membranes against plasticization in dense films. This study extends this promising crosslinking approach from dense films to industrially relevant asymmetric hollow fiber membranes. Crosslinkable asymmetric hollow fiber membranes were spun from a carboxylic acid containing polyimide, 6FDA-DAM:DABA. Dope and spinning conditions were optimized to obtain fibers with a defect-free selective skin layer. It is found that slightly defective fibers suffered severe selectivity loss after thermal crosslinking, suggesting that defect-free property is essential to the performance of the resulting crosslinked hollow fiber membranes. The crosslinked fibers were tested for CO 2/CH 4 separation. The excellent plasticization resistance under high pressure feeds (with highest CO 2 partial pressure of 400psia) suggests that these robust membranes are promising for aggressive natural gas purification. © 2011 Elsevier B.V.

  1. Detergent-resistant membrane association of NS2 and E2 during hepatitis C virus replication.

    Science.gov (United States)

    Shanmugam, Saravanabalaji; Saravanabalaji, Dhanaranjani; Yi, MinKyung

    2015-04-01

    Previously, we demonstrated that the efficiency of hepatitis C virus (HCV) E2-p7 processing regulates p7-dependent NS2 localization to putative virus assembly sites near lipid droplets (LD). In this study, we have employed subcellular fractionations and membrane flotation assays to demonstrate that NS2 associates with detergent-resistant membranes (DRM) in a p7-dependent manner. However, p7 likely plays an indirect role in this process, since only the background level of p7 was detectable in the DRM fractions. Our data also suggest that the p7-NS2 precursor is not involved in NS2 recruitment to the DRM, despite its apparent targeting to this location. Deletion of NS2 specifically inhibited E2 localization to the DRM, indicating that NS2 regulates this process. Treatment of cells with methyl-β-cyclodextrin (MβCD) significantly reduced the DRM association of Core, NS2, and E2 and reduced infectious HCV production. Since disruption of the DRM localization of NS2 and E2, either due to p7 and NS2 defects, respectively, or by MβCD treatment, inhibited infectious HCV production, these proteins' associations with the DRM likely play an important role during HCV assembly. Interestingly, we detected the HCV replication-dependent accumulation of ApoE in the DRM fractions. Taking into consideration the facts that ApoE was shown to be a major determinant for infectious HCV particle production at the postenvelopment step and that the HCV Core protein strongly associates with the DRM, recruitment of E2 and ApoE to the DRM may allow the efficient coordination of Core particle envelopment and postenvelopment events at the DRM to generate infectious HCV production. The biochemical nature of HCV assembly sites is currently unknown. In this study, we investigated the correlation between NS2 and E2 localization to the detergent-resistant membranes (DRM) and HCV particle assembly. We determined that although NS2's DRM localization is dependent on p7, p7 was not targeted to these

  2. Nanofiltration and Tight Ultrafiltration Membranes for Natural Organic Matter Removal—Contribution of Fouling and Concentration Polarization to Filtration Resistance

    Directory of Open Access Journals (Sweden)

    Joerg Winter

    2017-07-01

    Full Text Available Nanofiltration (NF and tight ultrafiltration (tight UF membranes are a viable treatment option for high quality drinking water production from sources with high concentrations of contaminants. To date, there is limited knowledge regarding the contribution of concentration polarization (CP and fouling to the increase in resistance during filtration of natural organic matter (NOM with NF and tight UF. Filtration tests were conducted with NF and tight UF membranes with molecular weight cut offs (MWCOs of 300, 2000 and 8000 Da, and model raw waters containing different constituents of NOM. When filtering model raw waters containing high concentrations of polysaccharides (i.e., higher molecular weight NOM, the increase in resistance was dominated by fouling. When filtering model raw waters containing humic substances (i.e., lower molecular weight NOM, the increase in filtration resistance was dominated by CP. The results indicate that low MWCO membranes are better suited for NOM removal, because most of the NOM in surface waters consist mainly of humic substances, which were only effectively rejected by the lower MWCO membranes. However, when humic substances are effectively rejected, CP can become extensive, leading to a significant increase in filtration resistance by the formation of a cake/gel layer at the membrane surface. For this reason, cross-flow operation, which reduces CP, is recommended.

  3. Nanofiltration and Tight Ultrafiltration Membranes for Natural Organic Matter Removal-Contribution of Fouling and Concentration Polarization to Filtration Resistance.

    Science.gov (United States)

    Winter, Joerg; Barbeau, Benoit; Bérubé, Pierre

    2017-07-02

    Nanofiltration (NF) and tight ultrafiltration (tight UF) membranes are a viable treatment option for high quality drinking water production from sources with high concentrations of contaminants. To date, there is limited knowledge regarding the contribution of concentration polarization (CP) and fouling to the increase in resistance during filtration of natural organic matter (NOM) with NF and tight UF. Filtration tests were conducted with NF and tight UF membranes with molecular weight cut offs (MWCOs) of 300, 2000 and 8000 Da, and model raw waters containing different constituents of NOM. When filtering model raw waters containing high concentrations of polysaccharides (i.e., higher molecular weight NOM), the increase in resistance was dominated by fouling. When filtering model raw waters containing humic substances (i.e., lower molecular weight NOM), the increase in filtration resistance was dominated by CP. The results indicate that low MWCO membranes are better suited for NOM removal, because most of the NOM in surface waters consist mainly of humic substances, which were only effectively rejected by the lower MWCO membranes. However, when humic substances are effectively rejected, CP can become extensive, leading to a significant increase in filtration resistance by the formation of a cake/gel layer at the membrane surface. For this reason, cross-flow operation, which reduces CP, is recommended.

  4. Effect of Evaporation Time on Separation Performance of Polysulfone/Cellulose Acetate (PSF/CA) Membrane

    Science.gov (United States)

    Syahbanu, Intan; Piluharto, Bambang; Khairi, Syahrul; Sudarko

    2018-01-01

    Polysulfone and cellulose acetate are common material in separation. In this research, polysulfone/cellulose actetate (PSF/CA) blend membrane was prepared. The aim of this research was to study effect of evaporation time in casting of PSF/CA membrane and its performance in filtration. CA was obtained by acetylation process of bacterial cellulose (BC) from fermentation of coconut water. Fourier Transform Infra Red (FTIR) Spectroscopy was used to examine functional groups of BC, CA and commercial cellulose acetate. Subtitution of acetyl groups determined by titration method. Blend membranes were prepared through phase inversion technique in which composition of PSF/PEG/CA/NMP(%w) was 15/5/5/75. Polyethyleneglycol (PEG) and N-methyl-2-pyrrolidone (NMP) were act as pore forming agent and solvent, respectively. Variation of evaporation times were used as parameter to examine water uptake, flux, and morphology of PSF/CA blend membranes. FTIR spectra of CA show characteristic peak of acetyl group at 1220 cm-1 indicated that BC was acetylated succesfully. Degree of subtitution of BCA was found at 2.62. Highest water flux was performed at 2 bar obtained at 106.31 L.m-2.h-1 at 0 minute variation, and decrease as increasing evaporation time. Morphology of PSF/BCA blend membranes were investigated by Scanning Electron Microscopy (SEM) showed that porous asymetric membrane were formed.

  5. Zinc oxide-curcumin nanocomposite loaded collagen membrane as an effective material against methicillin-resistant coagulase-negative Staphylococci.

    Science.gov (United States)

    Soumya, K R; Snigdha, S; Sugathan, Sheela; Mathew, Jyothis; Radhakrishnan, E K

    2017-08-01

    Zinc oxide nanoparticles and curcumin are excellent antimicrobial agents. They have the potential to be used as alternative to antibiotics in wound infection management. In this study, ZnO-curcumin nanocomposite was synthesized and characterized. Physical adsorption of the nanocomposite onto collagen skin wound dressing was conducted and structural investigation was carried out by SEM. Antimicrobial assay, minimum inhibitory concentration (MIC), and viability assays of different concentrations of nanocomposite loaded collagen membrane were conducted against clinically isolated methicillin-resistant coagulase-negative Staphylococci (MRCoNS), such as S. epidermidis, S. hemolyticus, and S. saprophyticus. The nanocomposite showed excellent anti-CoNS activity on time kill assay with the MIC value of 195 µg/mL against S. epidermidis, S. hemolyticus and 390 µg/mL against S. saprophyticus. The nanocomposite loaded collagen membrane also showed excellent in vitro antistaphylococcal activity. This study may lead to the development of antibiotic alternate strategies to control and limit the MRCoNS in wound-related infections.

  6. Analyses of interfacial resistances in a membrane-electrode assembly for a proton exchange membrane fuel cell using symmetrical impedance spectroscopy.

    Science.gov (United States)

    Seo, Seok-Jun; Woo, Jung-Je; Yun, Sung-Hyun; Lee, Hong-Joo; Park, Jin-Soo; Xu, Tongwen; Yang, Tae-Hyun; Lee, Jaeyoung; Moon, Seung-Hyeon

    2010-12-14

    Interfacial resistances between the polymer electrolyte membrane (PEM) and catalyst layer (CL) in membrane-electrode assemblies (MEAs) have yet to be systematically examined in spite of its great importance on the fuel cell performance. In order to investigate ionic transport through the PEM/CL interface, the symmetrical impedance mode (SIM) was employed in which the same type of gas was injected (H(2)/H(2)). In this study, the ionic transport resistance at the interface was controlled by the additionally sprayed outer ionomer on the surface of each CL. Effectiveness of the outer ionomer on ionic transport at the interface was quantitatively explained by the reduced contact, proton hydration, and charge transport resistances in the SIM. To characterize the ionic transport resistance, the concept of total resistance (R(tot)) in the SIM was introduced, representing the overall ohmic loss due to proton transport in an MEA. This concept was successfully supported via an agreement of the interpretation and the linear correlation that was obtained between the admittance (1/R(tot)) and the performance of a fuel cell in the ohmic loss region. This correlation will enable researchers to predict the performance of a fuel cell under the influence of proton transport by examining the R(tot) in the SIM.

  7. 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...

  8. 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

  9. Overexpression of antibiotic resistance genes in hospital effluents over time.

    Science.gov (United States)

    Rowe, Will P M; Baker-Austin, Craig; Verner-Jeffreys, David W; Ryan, Jim J; Micallef, Christianne; Maskell, Duncan J; Pearce, Gareth P

    2017-06-01

    Effluents contain a diverse abundance of antibiotic resistance genes that augment the resistome of receiving aquatic environments. However, uncertainty remains regarding their temporal persistence, transcription and response to anthropogenic factors, such as antibiotic usage. We present a spatiotemporal study within a river catchment (River Cam, UK) that aims to determine the contribution of antibiotic resistance gene-containing effluents originating from sites of varying antibiotic usage to the receiving environment. Gene abundance in effluents (municipal hospital and dairy farm) was compared against background samples of the receiving aquatic environment (i.e. the catchment source) to determine the resistome contribution of effluents. We used metagenomics and metatranscriptomics to correlate DNA and RNA abundance and identified differentially regulated gene transcripts. We found that mean antibiotic resistance gene and transcript abundances were correlated for both hospital ( ρ  = 0.9, two-tailed P  resistance genes ( bla GES and bla OXA ) were overexpressed in all hospital effluent samples. High β-lactam resistance gene transcript abundance was related to hospital antibiotic usage over time and hospital effluents contained antibiotic residues. We conclude that effluents contribute high levels of antibiotic resistance genes to the aquatic environment; these genes are expressed at significant levels and are possibly related to the level of antibiotic usage at the effluent source. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.

  10. Enhancing the formation and shear resistance of nitrifying biofilms on membranes by surface modification

    DEFF Research Database (Denmark)

    Lackner, Susanne; Holmberg, Maria; Terada, Akihiko

    2009-01-01

    Polypropylene (PP) membranes and polyethylene (PE) surfaces were modified to enhance formation and shear resistance of nitrifying biofilms for wastewater treatment applications. A combination of plasma polymerization and wet chemistry was employed to ultimately introduce poly(ethyleneglycol) (PEG...... structure might be possible explanations of the superiority of the -PEG-NH2 modification. The success of the-PEG-NH2 modification was independent of the original surface and might, therefore, be used in wastewater treatment bioreactors to improve reactor performance by making biofilm formation more stable...... similar trends: biofilms on -PEG-NH2 modified surfaces were much stronger compared to the other modifications and the unmodified reference surfaces. Electrostatic interactions between the protonated amino group and negatively charged bacteria as well as PEG chain density which can affect the surface...

  11. Dendrimeric Thin-Film Composite Membranes: Free Volume, Roughness, and Fouling Resistance

    KAUST Repository

    Phuoc, Duong

    2017-11-10

    Copolyamide films with a thickness from 50 to 780 nm were fabricated by interfacial polymerization between mixtures of m-phenylene diamine and primary amine-terminated polyamidoamine dendrimers (PAMAM) in the aqueous phase and trimesoyl chloride (TMC) in the organic phase. Different PAMAM generations (G0, d = 15 Å, Z = 4; G3, d = 36 Å, Z = 32; and G5, d = 54, Z = 128, where d is the measured diameter and Z is the number of terminal groups) and concentrations were used to obtain copolyamide films with different crosslinked structures. The influences of the concentration and degree of branching (PAMAM generation) on free volume were analysed via positon annihilation spectroscopy (PAS) and correlated with the separation properties of copolyamide films. Besides, surface and intrinsic properties of copolyamide films under different conditions were compared. The high hydrophilicity of PAMAM in the copolyamide network leads to the formation of a hydration layer on the copolyamide surface, which minimizes fouling. The separation performance of copolyamide membranes with various PAMAM networks was investigated in forward osmosis (FO) experiments. Understanding the correlation between the PAMAM structure/concentration, free volume, thickness, and surface intrinsic properties leads to the design of suitable fouling resistant thin-film composite membranes in a single interfacial polymerization process.

  12. Pentiptycene-based polyurethane with enhanced mechanical properties and CO2-plasticization resistance for thin film gas separation membranes.

    Science.gov (United States)

    Pournaghshband Isfahani, Ali; Sadeghi, Morteza; Wakimoto, Kazuki; Shrestha, Binod Babu; Bagheri, Rouhollah; Sivaniah, Easan; Ghalei, Behnam

    2018-04-30

    Development of thin film composite (TFC) membranes offers an opportunity to achieve the permeability/selectivity requirements for optimum CO2 separation performance. However, the durability and performance of thin film gas separation membranes are mostly challenged by weak mechanical properties and high CO2 plasticization. Here, we designed new polyurethane (PU) structures with bulky aromatic chain extenders that afford preferred mechanical properties for ultra-thin film formation. An improvement of about 1500% in Young's modulus and 600% in hardness was observed for pentiptycene-based PUs compared to typical PU membranes. Single (CO2, H2, CH4, and N2) and mixed (CO2/N2 and CO2/CH4) gas permeability tests were performed on the PU membranes. The resulting TFC membranes showed a high CO2 permeance up to 1400 GPU (10-6 cm3(STP) cm-2s-1 cmHg-1) and the CO2/N2 and CO2/H2 selectivities of about 22 and 2.1, respectively. The enhanced mechanical properties of pentiptycene-based PUs results in high performance thin membranes with the similar selectivity of the bulk polymer. The thin film membranes prepared from pentiptycene-based PUs also showed a two-fold enhanced plasticization resistance compared to non-pentiptycene containing PU membranes.

  13. Detailed models for timing and efficiency in resistive plate chambers

    CERN Document Server

    AUTHOR|(CDS)2067623; Lippmann, Christian

    2003-01-01

    We discuss detailed models for detector physics processes in Resistive Plate Chambers, in particular including the effect of attachment on the avalanche statistics. In addition, we present analytic formulas for average charges and intrinsic RPC time resolution. Using a Monte Carlo simulation including all the steps from primary ionization to the front-end electronics we discuss the dependence of efficiency and time resolution on parameters like primary ionization, avalanche statistics and threshold.

  14. Resistance patterns among multidrug-resistant tuberculosis patients in greater metropolitan Mumbai: trends over time.

    Science.gov (United States)

    Dalal, Alpa; Pawaskar, Akshay; Das, Mrinalini; Desai, Ranjan; Prabhudesai, Pralhad; Chhajed, Prashant; Rajan, Sujeet; Reddy, Deepesh; Babu, Sajit; Jayalakshmi, T K; Saranchuk, Peter; Rodrigues, Camilla; Isaakidis, Petros

    2015-01-01

    While the high burden of multidrug-resistant tuberculosis (MDR-TB) itself is a matter of great concern, the emergence and rise of advanced forms of drug-resistance such as extensively drug-resistant TB (XDR-TB) and extremely drug-resistant TB (XXDR-TB) is more troubling. The aim of this study was to investigate the trends over time of patterns of drug resistance in a sample of MDR-TB patients in greater metropolitan Mumbai, India. This was a retrospective, observational study of drug susceptibility testing (DST) results among MDR-TB patients from eight health care facilities in greater Mumbai between 2005 and 2013. We classified resistance patterns into four categories: MDR-TB, pre-XDR-TB, XDR-TB and XXDR-TB. A total of 340 MDR-TB patients were included in the study. Pre-XDR-TB was the most common form of drug-resistant TB observed overall in this Mumbai population at 56.8% compared to 29.4% for MDR-TB. The proportion of patients with MDR-TB was 39.4% in the period 2005-2007 and 27.8% in 2011-2013, while the proportion of those with XDR-TB and XXDR-TB was changed from 6.1% and 0% respectively to 10.6% and 5.6% during the same time period. During the same periods, the proportions of patients with ofloxacin, moxifloxacin and ethionamide resistance significantly increased from 57.6% to 75.3%, from 60.0% to 69.5% and from 24.2% to 52.5% respectively (pMumbai highlight the need for individualized drug regimens, designed on the basis of DST results involving first- and second-line anti-TB drugs and treatment history of the patient. A drug-resistant TB case-finding strategy based on molecular techniques that identify only rifampicin resistance will lead to initiation of suboptimal treatment regimens for a significant number of patients, which may in turn contribute to amplification of resistance and transmission of strains with increasingly advanced resistance within the community.

  15. Ih equalizes membrane input resistance in a heterogeneous population of fusiform neurons in the dorsal cochlear nucleus.

    Directory of Open Access Journals (Sweden)

    Cesar Celis Ceballos

    2016-10-01

    Full Text Available In a neuronal population, several combinations of its ionic conductances are used to attain a specific firing phenotype. Some neurons present heterogeneity in their firing, generally produced by expression of a specific conductance, but how additional conductances vary along in order to homeostatically regulate membrane excitability is less known. Dorsal cochlear nucleus principal neurons, fusiform neurons, display heterogeneous spontaneous action potential activity and thus represent an appropriate model to study the role of different conductances in establishing firing heterogeneity. Particularly, fusiform neurons are divided into quiet, with no spontaneous firing, or active neurons, presenting spontaneous, regular firing. These modes are determined by the expression levels of an intrinsic membrane conductance, an inwardly rectifying potassium current (IKir. In this work, we tested whether other subthreshold conductances vary homeostatically to maintain membrane excitability constant across the two subtypes. We found that Ih expression covaries specifically with IKir in order to maintain membrane resistance constant. The impact of Ih on membrane resistance is dependent on the level of IKir expression, being much smaller in quiet neurons with bigger IKir, but Ih variations are not relevant for creating the quiet and active phenotypes. Finally, we demonstrate that the individual proportion of each conductance, and not their absolute conductance, is relevant for determining the neuronal firing mode. We conclude that in fusiform neurons the variations of their different subthreshold conductances are limited to specific conductances in order to create firing heterogeneity and maintain membrane homeostasis.

  16. Role of Individual Positive Charges in the Membrane Orientation and Activity of Transporters of the Small Multidrug Resistance Family

    NARCIS (Netherlands)

    Kolbusz, Magdalena A.; Slotboom, Dirk Jan; Lolkema, Juke S.

    2012-01-01

    The effect of individual positively charged residues on the orientation in the membrane was analyzed in three dual-topology transporters of the small. multidrug resistance (SMR) family: AAVE4701aave of Acidovorax avenae, EMREecol of Escherichia coli, and RRUA0272rrub of Rhodospirillum rubrum. It is

  17. Super-resolution microscopy reveals the insulin-resistance-regulated reorganization of GLUT4 on plasma membranes.

    Science.gov (United States)

    Gao, Lan; Chen, Junling; Gao, Jing; Wang, Hongda; Xiong, Wenyong

    2017-01-15

    GLUT4 (also known as SLC2A4) is essential for glucose uptake in skeletal muscles and adipocytes, which play central roles in whole-body glucose metabolism. Here, using direct stochastic optical reconstruction microscopy (dSTORM) to investigate the characteristics of plasma-membrane-fused GLUT4 at the single-molecule level, we have demonstrated that insulin and insulin resistance regulate the spatial organization of GLUT4 in adipocytes. Stimulation with insulin shifted the balance of GLUT4 on the plasma membrane toward a more dispersed configuration. In contrast, insulin resistance induced a more clustered distribution of GLUT4 and increased the mean number of molecules per cluster. Furthermore, our data demonstrate that the F 5 QQI motif and lipid rafts mediate the maintenance of GLUT4 clusters on the plasma membrane. Mutation of F 5 QQI (F 5 QQA-GLUT4) induced a more clustered distribution of GLUT4; moreover, destruction of lipid rafts in adipocytes expressing F 5 QQA-GLUT4 dramatically decreased the percentage of large clusters and the mean number of molecules per cluster. In conclusion, our data clarify the effects of insulin stimulation or insulin resistance on GLUT4 reorganization on the plasma membrane and reveal new pathogenic mechanisms of insulin resistance. © 2017. Published by The Company of Biologists Ltd.

  18. Staphylococcal phenotypes induced by naturally occurring and synthetic membrane-interactive polyphenolic β-lactam resistance modifiers.

    Directory of Open Access Journals (Sweden)

    Lucia Palacios

    Full Text Available Galloyl catechins, in particular (--epicatechin gallate (ECg, have the capacity to abrogate β-lactam resistance in methicillin-resistant strains of Staphylococcus aureus (MRSA; they also prevent biofilm formation, reduce the secretion of a large proportion of the exoproteome and induce profound changes to cell morphology. Current evidence suggests that these reversible phenotypic traits result from their intercalation into the bacterial cytoplasmic membrane. We have endeavoured to potentiate the capacity of ECg to modify the MRSA phenotype by stepwise removal of hydroxyl groups from the B-ring pharmacophore and the A:C fused ring system of the naturally occurring molecule. ECg binds rapidly to the membrane, inducing up-regulation of genes responsible for protection against cell wall stress and maintenance of membrane integrity and function. Studies with artificial membranes modelled on the lipid composition of the staphylococcal bilayer indicated that ECg adopts a position deep within the lipid palisade, eliciting major alterations in the thermotropic behaviour of the bilayer. The non-galloylated homolog (--epicatechin enhanced ECg-mediated effects by facilitating entry of ECg molecules into the membrane. ECg analogs with unnatural B-ring hydroxylation patterns induced higher levels of gene expression and more profound changes to MRSA membrane fluidity than ECg but adopted a more superficial location within the bilayer. ECg possessed a high affinity for the positively charged staphylococcal membrane and induced changes to the biophysical properties of the bilayer that are likely to account for its capacity to disperse the cell wall biosynthetic machinery responsible for β-lactam resistance. The ability to enhance these properties by chemical modification of ECg raises the possibility that more potent analogs could be developed for clinical evaluation.

  19. Staphylococcal Phenotypes Induced by Naturally Occurring and Synthetic Membrane-Interactive Polyphenolic β-Lactam Resistance Modifiers

    Science.gov (United States)

    Palacios, Lucia; Rosado, Helena; Micol, Vicente; Rosato, Adriana E.; Bernal, Patricia; Arroyo, Raquel; Grounds, Helen; Anderson, James C.; Stabler, Richard A.; Taylor, Peter W.

    2014-01-01

    Galloyl catechins, in particular (-)-epicatechin gallate (ECg), have the capacity to abrogate β-lactam resistance in methicillin-resistant strains of Staphylococcus aureus (MRSA); they also prevent biofilm formation, reduce the secretion of a large proportion of the exoproteome and induce profound changes to cell morphology. Current evidence suggests that these reversible phenotypic traits result from their intercalation into the bacterial cytoplasmic membrane. We have endeavoured to potentiate the capacity of ECg to modify the MRSA phenotype by stepwise removal of hydroxyl groups from the B-ring pharmacophore and the A:C fused ring system of the naturally occurring molecule. ECg binds rapidly to the membrane, inducing up-regulation of genes responsible for protection against cell wall stress and maintenance of membrane integrity and function. Studies with artificial membranes modelled on the lipid composition of the staphylococcal bilayer indicated that ECg adopts a position deep within the lipid palisade, eliciting major alterations in the thermotropic behaviour of the bilayer. The non-galloylated homolog (-)-epicatechin enhanced ECg-mediated effects by facilitating entry of ECg molecules into the membrane. ECg analogs with unnatural B-ring hydroxylation patterns induced higher levels of gene expression and more profound changes to MRSA membrane fluidity than ECg but adopted a more superficial location within the bilayer. ECg possessed a high affinity for the positively charged staphylococcal membrane and induced changes to the biophysical properties of the bilayer that are likely to account for its capacity to disperse the cell wall biosynthetic machinery responsible for β-lactam resistance. The ability to enhance these properties by chemical modification of ECg raises the possibility that more potent analogs could be developed for clinical evaluation. PMID:24699700

  20. Time between membrane rupture and delivery and septicemia in term neonates.

    Science.gov (United States)

    Herbst, Andreas; Källén, Karin

    2007-09-01

    To investigate how the interval between membrane rupture and delivery affects the risk of neonatal sepsis and whether duration of labor influences the risk. A registry study included 113,568 singleton infants born at term after a trial of labor (elective cesarean deliveries excluded). The incidence of a diagnosis of sepsis during the neonatal period was correlated to the interval between membrane rupture and delivery. Multiple logistic regression analysis was done with adjustments for maternal age, parity, infant gender, gestational age, birth weight, and duration of labor. Receiver operating characteristics curves were created to estimate the optimal cutoff of membrane rupture time associated with an increased risk of neonatal septicemia. The rate of neonatal sepsis was 0.3% at a membrane rupture to delivery interval below 6 hours, 0.5% at 6-18 hours, 0.8% at 18-24 hours, and 1.1% after 24 hours. The risk of neonatal sepsis increased independently and nearly linearly with duration of membrane rupture up to 36 hours, with an odds ratio of 1.29 for each 6-hour increase in membrane rupture duration. The risk also increased with birth weight, gestational age, primiparity, and male infant gender. Duration of labor was not an independent risk factor for neonatal sepsis. Receiver operating characteristics curve analysis revealed an area under the curve of 0.66, but a superior cutoff time limit for the risk of sepsis was not found. The risk of neonatal sepsis increases with duration of membrane rupture in a linear fashion during the first 36 hours, independently of labor duration. II.

  1. The membrane-associated form of α(s1-casein interacts with cholesterol-rich detergent-resistant microdomains.

    Directory of Open Access Journals (Sweden)

    Annabelle Le Parc

    Full Text Available Caseins, the main milk proteins, interact with colloidal calcium phosphate to form the casein micelle. The mesostructure of this supramolecular assembly markedly influences its nutritional and technological functionalities. However, its detailed molecular organization and the cellular mechanisms involved in its biogenesis have been only partially established. There is a growing body of evidence to support the concept that α(s1-casein takes center stage in casein micelle building and transport in the secretory pathway of mammary epithelial cells. Here we have investigated the membrane-associated form of α(s1-casein in rat mammary epithelial cells. Using metabolic labelling we show that α(s1-casein becomes associated with membranes at the level of the endoplasmic reticulum, with no subsequent increase at the level of the Golgi apparatus. From morphological and biochemical data, it appears that caseins are in a tight relationship with membranes throughout the secretory pathway. On the other hand, we have observed that the membrane-associated form of α(s1-casein co-purified with detergent-resistant membranes. It was poorly solubilised by Tween 20, partially insoluble in Lubrol WX, and substantially insoluble in Triton X-100. Finally, we found that cholesterol depletion results in the release of the membrane-associated form of α(s1-casein. These experiments reveal that the insolubility of α(s1-casein reflects its partial association with a cholesterol-rich detergent-resistant microdomain. We propose that the membrane-associated form of α(s1-casein interacts with the lipid microdomain, or lipid raft, that forms within the membranes of the endoplasmic reticulum, for efficient forward transport and sorting in the secretory pathway of mammary epithelial cells.

  2. Nanoclay embedded mixed matrix PVDF nanocomposite membrane: Preparation, characterization and biofouling resistance

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, Hamid [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Department of Civil Engineering, Razi University, 67149 Kermanshah (Iran, Islamic Republic of); Ghaemi, Negin, E-mail: negin_ghaemi@kut.ac.ir [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Madaeni, Sayed S. [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Daraei, Parisa [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Khadivi, Mohammad Ali [Friedrich-Alexander University, Erlangen-Nuremberg, Egerland Strasse 3, D-91058 Erlangen (Germany); Falsafi, Monir [Department of Chemistry, Faculty of Science, Razi University, 67149 Kermanshah (Iran, Islamic Republic of)

    2014-09-15

    Highlights: • Nanocomposite membranes were prepared by addition of OMMT to PVDF membrane. • Addition of nanoclay considerably increased the hydrophilicity of PVDF membrane. • Nanocomposite membranes had higher water flux and antifouling properties. • Fouling of membranes blended with nanoclay (<4 wt.%) reduced. - Abstract: In this paper, nanocomposite PVDF/nanoclay membranes were prepared with addition of different concentrations of organically modified montmorillonite (OMMT) into the polymeric casting solution using combination of solution dispersion and phase inversion methods. Membranes were characterized by use of X-ray diffraction (XRD), water contact angle, scanning electron microscopy (SEM) and atomic force microscopy (AFM), and their performances were evaluated in terms of pure water flux and fouling parameters. The surface hydrophilicity of all nanocomposites markedly improved compared to nascent PVDF. In addition, XRD patterns revealed the formation of intercalated layers of mineral clays in PVDF matrix. SEM and AFM images showed that addition of OMMT resulted in nanocomposite membranes with thinner skin layer and higher porosity rather than PVDF membranes. Pure water flux of PVDF/OMMT membranes increased significantly (particularly for fabricated membranes by 4 and 6 wt.% OMMT) compared to that of PVDF membrane. Moreover, nanocomposite membranes showed the elevated antifouling properties, and flux recovery of nascent PVDF membranes increased from 51 to 72% with addition of 2 wt.% OMMT nanoparticles. These nanocomposite membranes also offered a remarkable reusability and durability against biofouling.

  3. Designing CO2-resistant oxygen-selective mixed ionic-electronic conducting membranes: guidelines, recent advances, and forward directions.

    Science.gov (United States)

    Zhang, Chi; Sunarso, Jaka; Liu, Shaomin

    2017-05-22

    CO 2 resistance is an enabling property for the wide-scale implementation of oxygen-selective mixed ionic-electronic conducting (MIEC) membranes in clean energy technologies, i.e., oxyfuel combustion, clean coal energy delivery, and catalytic membrane reactors for greener chemical synthesis. The significant rise in the number of studies over the past decade and the major progress in CO 2 -resistant MIEC materials warrant systematic guidelines on this topic. To this end, this review features the pertaining aspects in addition to the recent status and advances of the two most promising membrane materials, perovskite and fluorite-based dual-phase materials. We explain how to quantify and design CO 2 resistant membranes using the Lewis acid-base reaction concept and thermodynamics perspective and highlight the relevant characterization techniques. For perovskite materials, a trade-off generally exists between CO 2 resistance and O 2 permeability. Fluorite materials, despite their inherent CO 2 resistance, typically have low O 2 permeability but this can be improved via different approaches including thin film technology and the recently developed minimum internal electronic short-circuit second phase and external electronic short-circuit decoration. We then elaborate the two main future directions that are centralized around the development of new oxide compositions capable of featuring simultaneously high CO 2 resistance and O 2 permeability and the exploitation of phase reactions to create a new conductive phase along the grain boundaries of dual-phase materials. The final part of the review discusses various complimentary characterization techniques and the relevant studies that can provide insights into the degradation mechanism of oxide-based materials upon exposure to CO 2 .

  4. The Natural Time Course of Membrane Alterations During Peritoneal Dialysis Is Partly Altered by Peritonitis

    NARCIS (Netherlands)

    van Esch, Sadie; Struijk, Dirk G.; Krediet, Raymond T.

    2016-01-01

    ♦ The quality of the peritoneal membrane can deteriorate over time. Exposure to glucose-based dialysis solutions is the most likely culprit. Because peritonitis is a common complication of peritoneal dialysis (PD), distinguishing between the effect of glucose exposure and a possible additive effect

  5. Nutritional Supplement of Hatchery Eggshell Membrane Improves Poultry Performance and Provides Resistance against Endotoxin Stress.

    Directory of Open Access Journals (Sweden)

    S K Makkar

    Full Text Available Eggshells are significant part of hatchery waste which consist of calcium carbonate crust, membranes, and proteins and peptides of embryonic origins along with other entrapped contaminants including microbes. We hypothesized that using this product as a nutritional additive in poultry diet may confer better immunity to the chickens in the paradigm of mammalian milk that enhances immunity. Therefore, we investigated the effect of hatchery eggshell membranes (HESM as a short term feed supplement on growth performance and immunity of chickens under bacterial lipopolysaccharide (LPS challenged condition. Three studies were conducted to find the effect of HESM supplement on post hatch chickens. In the first study, the chickens were fed either a control diet or diets containing 0.5% whey protein or HESM as supplement and evaluated at 5 weeks of age using growth, hematology, clinical chemistry, plasma immunoglobulins, and corticosterone as variables. The second and third studies were done to compare the effects of LPS on control and HESM fed birds at 5 weeks of age following at 4 and 24 h of treatment where the HESM was also sterilized with ethanol to deplete bacterial factors. HESM supplement caused weight gain in 2 experiments and decreased blood corticosterone concentrations. While LPS caused a significant loss in body weight at 24 h following its administration, the HESM supplemented birds showed significantly less body weight loss compared with the control fed birds. The WBC, heterophil/lymphocyte ratio, and the levels of IgG were low in chickens fed diets with HESM supplement compared with control diet group. LPS challenge increased the expression of pro-inflammatory cytokine gene IL-6 but the HESM fed birds showed its effect curtailed, also, which also, favored the up-regulation of anti-inflammatory genes compared with control diet fed chickens. Post hatch supplementation of HESM appears to improve performance, modulate immunity, and increase

  6. Nutritional Supplement of Hatchery Eggshell Membrane Improves Poultry Performance and Provides Resistance against Endotoxin Stress.

    Science.gov (United States)

    Makkar, S K; Rath, N C; Packialakshmi, B; Zhou, Z Y; Huff, G R; Donoghue, A M

    2016-01-01

    Eggshells are significant part of hatchery waste which consist of calcium carbonate crust, membranes, and proteins and peptides of embryonic origins along with other entrapped contaminants including microbes. We hypothesized that using this product as a nutritional additive in poultry diet may confer better immunity to the chickens in the paradigm of mammalian milk that enhances immunity. Therefore, we investigated the effect of hatchery eggshell membranes (HESM) as a short term feed supplement on growth performance and immunity of chickens under bacterial lipopolysaccharide (LPS) challenged condition. Three studies were conducted to find the effect of HESM supplement on post hatch chickens. In the first study, the chickens were fed either a control diet or diets containing 0.5% whey protein or HESM as supplement and evaluated at 5 weeks of age using growth, hematology, clinical chemistry, plasma immunoglobulins, and corticosterone as variables. The second and third studies were done to compare the effects of LPS on control and HESM fed birds at 5 weeks of age following at 4 and 24 h of treatment where the HESM was also sterilized with ethanol to deplete bacterial factors. HESM supplement caused weight gain in 2 experiments and decreased blood corticosterone concentrations. While LPS caused a significant loss in body weight at 24 h following its administration, the HESM supplemented birds showed significantly less body weight loss compared with the control fed birds. The WBC, heterophil/lymphocyte ratio, and the levels of IgG were low in chickens fed diets with HESM supplement compared with control diet group. LPS challenge increased the expression of pro-inflammatory cytokine gene IL-6 but the HESM fed birds showed its effect curtailed, also, which also, favored the up-regulation of anti-inflammatory genes compared with control diet fed chickens. Post hatch supplementation of HESM appears to improve performance, modulate immunity, and increase resistance of

  7. Effects of Hydraulic Retention Time on the Performance of a Membrane Bioreactor Treating Municipal Wastewater

    Directory of Open Access Journals (Sweden)

    Hadi Falahati

    2017-09-01

    Full Text Available There is an increasing demand for effluents of higher quality from wastewater treatment plants due to the more stringent quality standards as well as the increasing pressure on water resources worldwide, which calls for effluent recycle and reuse. Membrane bioreactors (MBRs have been recently gaining rapid popularity as a promising technology for wastewater treatment. In order to improve the quality of the effluent from Shiraz wastewater treatment plant, an on-site pilot-scale membrane bioreactor was operated for 9 months. The pilot plant built at Shiraz wastewater treatment plant consisted of an aerobic reactor and a membrane compartment containing one submerged hollow fiber membrane module. In this study, eleven different aerobic hydraulic retention times (HRT ranging from 2 to 12 hours were tested to determine the membrane capacity and to investigate the performance of the system in removing total ammonia nitrogen, organic matter, total suspended solids, and turbidity.The system recorded a perfectly stable removal efficiency over the whole experimental period, except for the 2-hour aerobic HRT, so that its COD and BOD reductions exceeded 95% and 99%, respectively. Moreover, the system achieved complete nitrification in a stable manner during the whole study period, except for the 2-hour aerobic operation period. TSS concentration was almost zero and turbidity was less than 1 NTU. Membrane capacity measurements showed an average flux of 5.5 Lm-2h-1 with a mean trans-membrane pressure difference of 30 kPa. Results showed that the MBR outperformed the conventional sewage treatment processes. Additionally, it was not affected by aerobic HRT changes (12, 10, 8, 6, 4, and 3h. Based on the effluent qulity, teh system may be recommended for application toward water reuse in industrial and agricultural settings

  8. New membranes made of sintered clay application to crossflow ...

    African Journals Online (AJOL)

    The new mineral membranes made of sintered clay are performed and characterized in terms of porosity, hydraulic resistance, pore diameter and mechanical resistance. It is shown that these membranes can be used as microfiltration membrane. The variations of the filtrate flux as a function of time are measured during the ...

  9. Membrane Active Small Molecules Show Selective Broad Spectrum Antibacterial Activity with No Detectable Resistance and Eradicate Biofilms.

    Science.gov (United States)

    Hoque, Jiaul; Konai, Mohini M; Gonuguntla, Spandhana; Manjunath, Goutham B; Samaddar, Sandip; Yarlagadda, Venkateswarlu; Haldar, Jayanta

    2015-07-23

    Treating bacterial biofilms with conventional antibiotics is limited due to ineffectiveness of the drugs and higher propensity to develop bacterial resistance. Development of new classes of antibacterial therapeutics with alternative mechanisms of action has become imperative. Herein, we report the design, synthesis, and biological evaluations of novel membrane-active small molecules featuring two positive charges, four nonpeptidic amide groups, and variable hydrophobic/hydrophilic (amphiphilic) character. The biocides synthesized via a facile methodology not only displayed good antibacterial activity against wild-type bacteria but also showed high activity against various drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and β-lactam-resistant Klebsiella pneumoniae. Further, these biocides not only inhibited the formation of biofilms but also disrupted the established S. aureus and E. coli biofilms. The membrane-active biocides hindered the propensity to develop bacterial resistance. Moreover, the biocides showed negligible toxicity against mammalian cells and thus bear potential to be used as therapeutic agents.

  10. Novel Nonporous Fouling-Resistant Enzymatic Composite Membranes for Waste Water Treatment

    National Research Council Canada - National Science Library

    Freeman, Benny D

    2005-01-01

    .... Permeation properties of thin-films made of these gels is also reported. Approximately 20 m2 of chitosan composite membrane were prepared at our industrial partner, Membrane Technology and Research (MTR...

  11. Improvement in the mechanical properties, proton conductivity, and methanol resistance of highly branched sulfonated poly(arylene ether)/graphene oxide grafted with flexible alkylsulfonated side chains nanocomposite membranes

    Science.gov (United States)

    Liu, Dong; Peng, Jinhua; Li, Zhuoyao; Liu, Bin; Wang, Lei

    2018-02-01

    Sulfonated polymer/graphene oxide (GO) nanocomposites exhibit excellent properties as proton exchange membranes. However, few investigations on highly branched sulfonated poly(arylene ether)s (HBSPE)/GO nanocomposites as proton exchange membranes are reported. In order to obtain HBSPE-based nanocomposite membranes with better dispersibility and properties, a novel GO containing flexible alkylsulfonated side chains (SGO) is designed and prepared for the first time in this work. The HBSPE/SGO nanocomposite membranes with excellent dispersibility are successfully prepared. The properties of these membranes, including the mechanical properties, ion-exchange capacity, water uptake, proton conductivity, and methanol resistance, are characterized. The nanocomposite membranes exhibit higher tensile strength (32.67 MPa), higher proton conductivity (0.39 S cm-1 at 80 °C) and lower methanol permeability (4.89 × 10-7 cm2 s-1) than the pristine membrane. The nanocomposite membranes also achieve a higher maximum power density (82.36 mW cm-2) than the pristine membrane (67.85 mW cm-2) in single-cell direct methanol fuel cell (DMFC) tests, demonstrating their considerable potential for applications in DMFCs.

  12. Analysis of bacteria-derived outer membrane vesicles using tunable resistive pulse sensing

    Science.gov (United States)

    Bogomolny, Evgeny; Hong, Jiwon; Blenkiron, Cherie; Simonov, Denis; Dauros, Priscila; Swift, Simon; Phillips, Anthony; Willmott, Geoff R.

    2015-03-01

    Accurate characterization of submicron particles within biological fluids presents a major challenge for a wide range of biomedical research. Detection, characterization and classification are difficult due to the presence of particles and debris ranging from single molecules up to particles slightly smaller than cells. Especial interest arises from extracellular vesicles (EVs) which are known to play a pivotal role in cell-signaling in multicellular organisms. Tunable resistive pulse sensing (TRPS) is increasingly proving to be a useful tool for high throughput particle-by-particle analysis of EVs and other submicron particles. This study examines the capability of TRPS for characterization of EVs derived from bacteria, also called outer membrane vesicles (OMVs). Measurement of a size distribution (124 +/- 3 nm modal diameter) and concentration (lower bound 7.4 x 109 mL-1) are demonstrated using OMVs derived from uropathogenic Escherichia coli. Important aspects of measurement are discussed, including sample preparation and size selection. Application of TRPS to study EVs could assist the development of these particles in clinical diagnostics and therapeutics.

  13. Silt density index and modified fouling index relation, and effect of pressure, temperature and membrane resistance

    NARCIS (Netherlands)

    Al-Hadidi, A.M.M.; Alhadidi, A.; Kemperman, Antonius J.B.; Blankert, B.; Blankert, B.; Schippers, J.C.; Wessling, Matthias; van der Meer, Walterus Gijsbertus Joseph

    2011-01-01

    Particulate matter present in feed water of reverse osmosis and nanofiltration membrane elements tends to deposit on the membrane surface and spacers. This type of fouling results in permeate flux decline, loss of product quality and membrane damage. To characterize the fouling potential of RO feed

  14. Detection of inhomogeneities in membrane ohmic resistance in geometrically complex systems

    DEFF Research Database (Denmark)

    Svirskis, G; Hounsgaard, J; Gutman, A

    2000-01-01

    DC field-evoked transients in arbitrarily shaped neurons and syncytia were analyzed theoretically. In systems with homogeneous passive membrane properties, the transients develop much faster than the membrane discharges. Conductance of the proximal membrane could be larger due to the injury impos...

  15. A membrane computing simulator of trans-hierarchical antibiotic resistance evolution dynamics in nested ecological compartments (ARES).

    Science.gov (United States)

    Campos, Marcelino; Llorens, Carlos; Sempere, José M; Futami, Ricardo; Rodriguez, Irene; Carrasco, Purificación; Capilla, Rafael; Latorre, Amparo; Coque, Teresa M; Moya, Andres; Baquero, Fernando

    2015-08-05

    Antibiotic resistance is a major biomedical problem upon which public health systems demand solutions to construe the dynamics and epidemiological risk of resistant bacteria in anthropogenically-altered environments. The implementation of computable models with reciprocity within and between levels of biological organization (i.e. essential nesting) is central for studying antibiotic resistances. Antibiotic resistance is not just the result of antibiotic-driven selection but more properly the consequence of a complex hierarchy of processes shaping the ecology and evolution of the distinct subcellular, cellular and supra-cellular vehicles involved in the dissemination of resistance genes. Such a complex background motivated us to explore the P-system standards of membrane computing an innovative natural computing formalism that abstracts the notion of movement across membranes to simulate antibiotic resistance evolution processes across nested levels of micro- and macro-environmental organization in a given ecosystem. In this article, we introduce ARES (Antibiotic Resistance Evolution Simulator) a software device that simulates P-system model scenarios with five types of nested computing membranes oriented to emulate a hierarchy of eco-biological compartments, i.e. a) peripheral ecosystem; b) local environment; c) reservoir of supplies; d) animal host; and e) host's associated bacterial organisms (microbiome). Computational objects emulating molecular entities such as plasmids, antibiotic resistance genes, antimicrobials, and/or other substances can be introduced into this framework and may interact and evolve together with the membranes, according to a set of pre-established rules and specifications. ARES has been implemented as an online server and offers additional tools for storage and model editing and downstream analysis. The stochastic nature of the P-system model implemented in ARES explicitly links within and between host dynamics into a simulation, with

  16. Role of the Outer Membrane Protein OprD2 in Carbapenem-Resistance Mechanisms of Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Jilu Shen

    Full Text Available We investigated the relationship between the outer membrane protein OprD2 and carbapenem-resistance in 141 clinical isolates of Pseudomonas aeruginosa collected between January and December 2013 from the First Affiliated Hospital of Anhui Medical University in China. Agar dilution methods were employed to determine the minimum inhibitory concentration of meropenem (MEM and imipenem (IMP for P. aeruginosa. The gene encoding OprD2 was amplified from141 P. aeruginosa isolates and analyzed by PCR and DNA sequencing. Differences between the effects of IMPR and IMPS groups on the resistance of the P. aeruginosa were observed by SDS-poly acrylamide gel electrophoresis (SDS-PAGE. Three resistance types were classified in the 141 carbapenem-resistant P. aeruginosa (CRPA isolates tested, namely IMPRMEMR (66.7%, IMPRMEMS (32.6%, and IMPRMEMS (0.7%. DNA sequencing revealed significant diverse gene mutations in the OprD2-encoding gene in these strains. Thirty-four strains had large fragment deletions in the OprD2gene, in 6 strains the gene contained fragment inserts, and in 96 resistant strains, the gene featured small fragment deletions or multi-site mutations. Only 4 metallo-β-lactamase strains and 1 imipenem-sensitive (meropenem-resistant strain showed a normal OprD2 gene. Using SDS-PAGE to detect the outer membrane protein in 16 CRPA isolates, it was found that 10 IMPRMEMR strains and 5 IMPRMEMS strains had lost the OprD2 protein, while the IMPSMEMR strain contained a normal 46-kDa protein. In conclusion, mutation or loss of the OprD2-encoding gene caused the loss of OprD2, which further led to carbapenem-resistance of P. aeruginosa. Our findings provide insights into the mechanism of carbapenem resistance in P. aeruginosa.

  17. Role of the Outer Membrane Protein OprD2 in Carbapenem-Resistance Mechanisms of Pseudomonas aeruginosa.

    Science.gov (United States)

    Shen, Jilu; Pan, Yaping; Fang, Yaping

    2015-01-01

    We investigated the relationship between the outer membrane protein OprD2 and carbapenem-resistance in 141 clinical isolates of Pseudomonas aeruginosa collected between January and December 2013 from the First Affiliated Hospital of Anhui Medical University in China. Agar dilution methods were employed to determine the minimum inhibitory concentration of meropenem (MEM) and imipenem (IMP) for P. aeruginosa. The gene encoding OprD2 was amplified from141 P. aeruginosa isolates and analyzed by PCR and DNA sequencing. Differences between the effects of IMPR and IMPS groups on the resistance of the P. aeruginosa were observed by SDS-poly acrylamide gel electrophoresis (SDS-PAGE). Three resistance types were classified in the 141 carbapenem-resistant P. aeruginosa (CRPA) isolates tested, namely IMPRMEMR (66.7%), IMPRMEMS (32.6%), and IMPRMEMS (0.7%). DNA sequencing revealed significant diverse gene mutations in the OprD2-encoding gene in these strains. Thirty-four strains had large fragment deletions in the OprD2gene, in 6 strains the gene contained fragment inserts, and in 96 resistant strains, the gene featured small fragment deletions or multi-site mutations. Only 4 metallo-β-lactamase strains and 1 imipenem-sensitive (meropenem-resistant) strain showed a normal OprD2 gene. Using SDS-PAGE to detect the outer membrane protein in 16 CRPA isolates, it was found that 10 IMPRMEMR strains and 5 IMPRMEMS strains had lost the OprD2 protein, while the IMPSMEMR strain contained a normal 46-kDa protein. In conclusion, mutation or loss of the OprD2-encoding gene caused the loss of OprD2, which further led to carbapenem-resistance of P. aeruginosa. Our findings provide insights into the mechanism of carbapenem resistance in P. aeruginosa.

  18. Effect of cholesterol depletion and temperature on the isolation of detergent-resistant membranes from human erythrocytes.

    Science.gov (United States)

    Domingues, Cleyton C; Ciana, Annarita; Buttafava, Armando; Casadei, Bruna Renata; Balduini, Cesare; de Paula, Eneida; Minetti, Giampaolo

    2010-04-01

    Transient lateral microdomains or lipid rafts play important roles in many physiological membrane-mediated cell processes. Detergent-resistant membranes (DRMs) are good models for the study of lipid rafts. Here we report that DRMs can be obtained by treating human erythrocytes with the nonionic detergents Triton X-100 or octaethylene glycol monododecyl ether (C(12)E(8)) at 37 degrees C, and by treatment at 4 degrees C of cholesterol-depleted erythrocytes. Electron paramagnetic resonance with spin labels inserted at different membrane depths (5- and 16-doxyl stearic acids, 5-SASL and 16-SASL) were used to measure the order parameter (S) of the cell membranes and DRMs. We previously reported significantly higher S values in DRMs with respect to intact erythrocyte membranes. Here we show that higher S values were still measurable in DRMs prepared from intact erythrocytes at 37 degrees C, or from cholesterol-depleted cells at 4 degrees C, for both detergents. For 5-SASL only, increased S values were measured in 4 degrees C DRMs obtained from cholesterol-depleted versus intact erythrocytes. Flotillin-2, a protein marker of lipid rafts, was found in DRMs from intact cells in trace amounts but it was sensitively increased in C(12)E(8) DRMs prepared at 4 degrees C from cholesterol-depleted erythrocytes, while the membrane-skeletal proteins spectrin and actin were excluded from both Triton X-100 and C(12)E(8) DRMs. However, contrary to the 4 degrees C treatment results, flotillin-2 and stomatin were not resistant to Triton X-100 and C(12)E(8) treatment at physiological temperature. The role of cholesterol in DRMs formation is discussed and the results presented provide further support for the use of C(12)E(8) to the study of DRMs.

  19. Antibiotic Resistance and Regulation of the Gram-Negative Bacterial Outer Membrane Barrier by Host Innate Immune Molecules

    Directory of Open Access Journals (Sweden)

    Samuel I. Miller

    2016-09-01

    Full Text Available The Gram-negative outer membrane is an important barrier that provides protection against toxic compounds, which include antibiotics and host innate immune molecules such as cationic antimicrobial peptides. Recently, significant research progress has been made in understanding the biogenesis, regulation, and functioning of the outer membrane, including a recent paper from the laboratory of Dr. Brett Finlay at the University of British Columbia (J. van der Heijden et al., mBio 7:e01238-16, 2016, http://dx.doi.org/10.1128/mBio.01541-16. These investigators demonstrate that toxic oxygen radicals, such as those found in host tissues, regulate outer membrane permeability by altering the outer membrane porin protein channels to regulate the influx of oxygen radicals as well as β-lactam antibiotics. This commentary provides context about this interesting paper and discusses the prospects of utilizing increased knowledge of outer membrane biology to develop new antibiotics for antibiotic-resistant Gram-negative bacteria.

  20. Testing and design of radon resisting membranes based on the experience from the Czech Republic

    International Nuclear Information System (INIS)

    Jiranek, M.

    2004-01-01

    Testing of barrier properties of insulating materials against radon is usually based on the measurement of the radon diffusion coefficient. Presented report summarizes results of radon diffusion coefficients measurements in more than 120 insulating materials obtained throughout Europe. All measurements were performed by the Czech Technical University, Faculty of Civil Engineering in cooperation with the Radiation Protection Institute. We have found out that great differences exist in diffusion properties, because the diffusion coefficients vary within eight orders from 10 -15 m 2 /s to 10 -8 m 2 /s. For each material category of different chemical composition statistical evaluation of results is presented. Possibilities of usage of the radon diffusion coefficient for the design of radon resisting membranes are discussed. Based on the experience from the Czech Republic the paper is trying to show that controlling applicability of membranes by setting of the upper limit for the radon diffusion coefficient is not a convenient approach. The main reason is that it is almost impossible to choose correctly one limit value for the whole Europe. The second reason is that a great number of common waterproofing materials have their radon diffusion coefficients above the probable limit value. As a consequence of this the protection against radon will be solved preferably by materials with Al foils, which is from the technical point of view meaningless, because membranes with Al foils have very low elongation and therefore they can very easily loose their barrier properties by destroying of the Al foil. The paper will show that it seems to be reasonable to replace strict limits by the real design of the insulation in dependence on particular building and soil characteristics. The design is proposed to be based on the calculation of the insulation thickness according to the formula: d ≥ l.arc sinh ((α 1 .l.λ.C S .(A f + A w ))/C dif .n.V)) (in m), where C S is the third

  1. Measuring Resistive Wall Mode Stability in Real-time

    Science.gov (United States)

    Hanson, J. M.; Lanctot, M. J.; Navratil, G. A.; Reimerdes, H.; Strait, E. J.

    2009-11-01

    Measurements of the plasma response to externally applied, low-n magnetic fields can be used to determine the resistive wall mode (RWM) stability of the plasma equilibrium. Such a method, if implemented as a real-time algorithm, can be used to gate error field correction, profile control, and RWM feedback control algorithms, enabling operation close to the no-wall stability limit. In addition, the stability estimate can be used to directly update parameters in an advanced RWM controller as the plasma evolves. We have developed an efficient scheme that uses an external field rotating at a single fixed frequency. Because only one frequency is applied, the plasma response can be calculated from measurements by Fourier-analyzing the measurements at only the applied frequency and subtracting the known vacuum pickup due to the control coils. This single-frequency, Fourier-domain analysis uses a small number of arithmetical operations, which is a requisite for real-time implementation.

  2. In-plane resolved in-situ measurements of the membrane resistance in PEFCs

    Energy Technology Data Exchange (ETDEWEB)

    Buechi, F.N.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The conductivity of the membrane is a limiting factor for the efficiency and power density of PEFCs. Because this conductivity is strongly dependent on the membrane hydration, water management is an important aspect of PEFC optimisation. Single cell model experiments were made in order to determine the in-plane hydration of a Nafion{sup R} membrane under fuel cell conditions as function of the gas humidities. (author) 4 fig., 3 refs.

  3. Concept of Compound Retention Time for Organic Micro Pollutants in Anaerobic Membrane Bioreactor with Nanofiltration

    KAUST Repository

    Pan, Jiangjiang

    2011-12-01

    Organic micropollutants (OMPs) have received more and more attention in recent years due to their potential harmful effects on public health and aquatic ecosystems, and eliminating OMPs in wastewater treatment systems is an important solution to control OMPs wastage. An innovative hybrid process, anaerobic membrane bioreactor with nanofiltration (AnMBR-NF), in which enhanced OMPs removal is possible based on the concept of compound retention time (CRT) through coupling anaerobic biodegradation and NF rejection, is proposed and examined in terms of preliminary feasibility in this study. First, NF membrane screening through sludge water dead-end filtration tests demonstrated that KOCH NF200 (molecular weight cut-off (MWCO) 200 Da, acid/base stable) performed best in organic matter rejection. Then, selected OMPs (ketobrofen and naproxen) in MQ water and a biologically treated wastewater matrix were filtered through NF200 under constant-pressure dead-end mode, with and without stirring, and several methods (contact angle, scanning electronic microscopy, Zeta potential, Fourier transform infra-red spectroscopy) were used to characterize membranes. Results show selected OMPs in MQ could be rejected (about 40%) by a clean NF200 membrane. The main rejection mechanism was initial absorption by the membrane followed by size exclusion (electric charge interaction plays a less important role). The wastewater matrix could enhance the rejection significantly (up to 90%) because effluent organic matter (EfOM) enhanced size exclusion and electric charge interaction through blocking membrane pores and forming a gel layer as well as binding some OMPs through partitioning followed by retention by NF. Third, an anaerobic bioreactor was set up to evaluate the anaerobic biodegradability of selected OMPs. Results showed selected OMPs could be absorbed by sludge and reached equilibrium within one day, and then were consumed by anaerobic microorganism with a half life 9.4 days for

  4. 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.

  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.

  6. 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

  7. Real-Time Remote Monitoring of Temperature and Humidity Within a Proton Exchange Membrane Fuel Cell Using Flexible Sensors

    Science.gov (United States)

    Kuo, Long-Sheng; Huang, Hao-Hsiu; Yang, Cheng-Hao; Chen, Ping-Hei

    2011-01-01

    This study developed portable, non-invasive flexible humidity and temperature microsensors and an in situ wireless sensing system for a proton exchange membrane fuel cell (PEMFC). The system integrated three parts: a flexible capacitive humidity microsensor, a flexible resistive temperature microsensor, and a radio frequency (RF) module for signal transmission. The results show that the capacitive humidity microsensor has a high sensitivity of 0.83 pF%RH−1 and the resistive temperature microsensor also exhibits a high sensitivity of 2.94 × 10−3 °C−1. The established RF module transmits the signals from the two microsensors. The transmission distance can reach 4 m and the response time is less than 0.25 s. The performance measurements demonstrate that the maximum power density of the fuel cell with and without these microsensors are 14.76 mW·cm−2 and 15.90 mW·cm−2, with only 7.17% power loss. PMID:22164099

  8. Osmotic tolerance of avian spermatozoa: Influence of time, temperature, cryoprotectant and membrane ion pump function on sperm viability

    Science.gov (United States)

    Blanco, J.M.; Long, J.A.; Gee, G.; Donoghue, A.M.; Wildt, D.E.

    2008-01-01

    Potential factors influencing sperm survival under hypertonic conditions were evaluated in the Sandhill crane (Grus canadensis) and turkey (Meleagridis gallopavo). Sperm osmotolerance (300-3000 mOsm/kg) was evaluated after: (1) equilibration times of 2, 10, 45 and 60 min at 4 ?C versus 21 ?C; (2) pre-equilibrating with dimethylacetamide (DMA) or dimethylsulfoxide (Me2SO) at either 4 ?C or 21 ?C; and (3) inhibition of the Na+/K+ and the Na+/H+ antiporter membrane ionic pumps. Sperm viability was assessed using the eosin-nigrosin live/dead stain. Species-specific differences occurred in response to hypertonic conditions with crane sperm remaining viable under extreme hypertonicity (3000 mOsm/kg), whereas turkey sperm viability was compromised with only slightly hypertonic (500 mOsm/kg) conditions. The timing of spermolysis under hypertonic conditions was also species-specific, with a shorter interval for turkey (2 min) than crane (10 min) sperm. Turkey sperm osmotolerance was slightly improved by lowering the incubation temperature from 21 to 4 ?C. Pre-equilibrating sperm with DMA reduced the incidence of hypertonic spermolysis only in the crane, at both room and refrigeration temperature. Inhibiting the Na+/K+ and the Na+/H+ antiporter membrane ion pumps did not impair resistance of crane and turkey spermatozoa to hypertonic stress; pump inhibition actually increased turkey sperm survival compared to control sperm. Results demonstrate marked species specificity in osmotolerance between crane and turkey sperm, as well as in the way temperature and time of exposure affect sperm survival under hypertonic conditions. Differences are independent of the role of osmotic pumps in these species.

  9. Membrane undulations in a structured fluid: Universal dynamics at intermediate length and time scales.

    Science.gov (United States)

    Granek, Rony; Diamant, Haim

    2018-01-05

    The dynamics of membrane undulations inside a viscous solvent is governed by distinctive, anomalous, power laws. Inside a viscoelastic continuous medium these universal behaviors are modified by the specific bulk viscoelastic spectrum. Yet, in structured fluids the continuum limit is reached only beyond a characteristic correlation length. We study the crossover to this asymptotic bulk dynamics. The analysis relies on a recent generalization of the hydrodynamic interaction in structured fluids, which shows a slow spatial decay of the interaction toward the bulk limit. For membranes which are weakly coupled to the structured medium we find a wide crossover regime characterized by different, universal, dynamic power laws. We discuss various systems for which this behavior is relevant, and delineate the time regime over which it may be observed.

  10. Ion transport resistance in Microbial Electrolysis Cells with anion and cation exchange membranes

    NARCIS (Netherlands)

    Sleutels, T.H.J.A.; Hamelers, H.V.M.; Rozendal, R.A.; Buisman, C.J.N.

    2009-01-01

    Previous studies have shown that Microbial Electrolysis Cells (MECs) perform better when an anion exchange membrane (AEM) than when a cation exchange membrane (CEM) separates the electrode chambers. Here, we have further studied this phenomenon by comparing two analysis methods for

  11. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    DEFF Research Database (Denmark)

    Li, Zhenyu; Linares, Rodrigo Valladares; Bucs, Szilard

    2017-01-01

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused, by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin...

  12. Relationship of Triamine-Biocide Tolerance of Salmonella enterica Serovar Senftenberg to Antimicrobial Susceptibility, Serum Resistance and Outer Membrane Proteins

    Directory of Open Access Journals (Sweden)

    Bożena Futoma-Kołoch

    2017-07-01

    Full Text Available A new emerging phenomenon is the association between the incorrect use of biocides in the process of disinfection in farms and the emergence of cross-resistance in Salmonella populations. Adaptation of the microorganisms to the sub-inhibitory concentrations of the disinfectants is not clear, but may result in an increase of sensitivity or resistance to antibiotics, depending on the biocide used and the challenged Salmonella serovar. Exposure of five Salmonella enterica subsp. enterica serovar Senftenberg (S. Senftenberg strains to triamine-containing disinfectant did not result in variants with resistance to antibiotics, but has changed their susceptibility to normal human serum (NHS. Three biocide variants developed reduced sensitivity to NHS in comparison to the sensitive parental strains, while two isolates lost their resistance to serum. For S. Senftenberg, which exhibited the highest triamine tolerance (6 × MIC and intrinsic sensitivity to 22.5% and 45% NHS, a downregulation of flagellin and enolase has been demonstrated, which might suggest a lower adhesion and virulence of the bacteria. This is the first report demonstrating the influence of biocide tolerance on NHS resistance. In conclusion, there was a potential in S. Senftenberg to adjust to the conditions, where the biocide containing triamine was present. However, the adaptation did not result in the increase of antibiotic resistance, but manifested in changes within outer membrane proteins’ patterns. The strategy of bacterial membrane proteins’ analysis provides an opportunity to adjust the ways of infection treatments, especially when it is connected to the life-threating bacteremia caused by Salmonella species.

  13. Relationship of Triamine-Biocide Tolerance of Salmonella enterica Serovar Senftenberg to Antimicrobial Susceptibility, Serum Resistance and Outer Membrane Proteins.

    Science.gov (United States)

    Futoma-Kołoch, Bożena; Dudek, Bartłomiej; Kapczyńska, Katarzyna; Krzyżewska, Eva; Wańczyk, Martyna; Korzekwa, Kamila; Rybka, Jacek; Klausa, Elżbieta; Bugla-Płoskońska, Gabriela

    2017-07-11

    A new emerging phenomenon is the association between the incorrect use of biocides in the process of disinfection in farms and the emergence of cross-resistance in Salmonella populations. Adaptation of the microorganisms to the sub-inhibitory concentrations of the disinfectants is not clear, but may result in an increase of sensitivity or resistance to antibiotics, depending on the biocide used and the challenged Salmonella serovar. Exposure of five Salmonella enterica subsp. enterica serovar Senftenberg ( S. Senftenberg) strains to triamine-containing disinfectant did not result in variants with resistance to antibiotics, but has changed their susceptibility to normal human serum (NHS). Three biocide variants developed reduced sensitivity to NHS in comparison to the sensitive parental strains, while two isolates lost their resistance to serum. For S. Senftenberg, which exhibited the highest triamine tolerance (6 × MIC) and intrinsic sensitivity to 22.5% and 45% NHS, a downregulation of flagellin and enolase has been demonstrated, which might suggest a lower adhesion and virulence of the bacteria. This is the first report demonstrating the influence of biocide tolerance on NHS resistance. In conclusion, there was a potential in S. Senftenberg to adjust to the conditions, where the biocide containing triamine was present. However, the adaptation did not result in the increase of antibiotic resistance, but manifested in changes within outer membrane proteins' patterns. The strategy of bacterial membrane proteins' analysis provides an opportunity to adjust the ways of infection treatments, especially when it is connected to the life-threating bacteremia caused by Salmonella species.

  14. Improving the corrosion resistance of proton exchange membrane fuel cell carbon supports by pentafluorophenyl surface functionalization

    Science.gov (United States)

    Forouzandeh, Farisa; Li, Xiaoan; Banham, Dustin W.; Feng, Fangxia; Joseph Kakanat, Abraham; Ye, Siyu; Birss, Viola

    2018-02-01

    In this study, the effect of surface functionalization on the electrochemical corrosion resistance of a high surface area, mesoporous colloid imprinted carbon powder (CIC), as well as microporous Vulcan carbon (VC, serving as the benchmark), was demonstrated, primarily for PEM fuel cell applications. CIC-22, which is highly hydrophilic and was synthesized with 22 nm silica colloid templates, and as-received, mildly hydrophobic, VC powders, were functionalized with 2,3,4,5,6-pentafluorophenyl (-PhF5) surface groups using a straightforward diazonium reduction reaction. These carbons were then subjected to corrosion testing, involving a potential cycling-step sequence in room temperature 0.5 M H2SO4. Using cyclic voltammetry and charge/time analysis, the double layer and pseudo-capacitive gravimetric charges of the carbons, prior to and after the application of these potential steps, were tracked in order to obtain information about surface area changes and the extent of carbon oxidation, respectively. It is shown that the corrosion resistance was improved by ca. 50-80% by surface functionalization, likely due to a combination of surface passivation (loss of carbon active sites) and increased surface hydrophobicity.

  15. Outer membrane proteomics of kanamycin-resistant Escherichia coli identified MipA as a novel antibiotic resistance-related protein.

    Science.gov (United States)

    Li, Hui; Zhang, Dan-feng; Lin, Xiang-min; Peng, Xuan-xian

    2015-06-01

    Antibiotic-resistant bacteria are a great threat to human health and food safety and there is an urgent need to understand the mechanisms of resistance for combating these bacteria. In the current study, comparative proteomic methodologies were applied to identify Escherichia coli K-12 outer membrane (OM) proteins related to kanamycin resistance. Mass spectrometry and western blotting results revealed that OM proteins TolC, Tsx and OstA were up-regulated, whereas MipA, OmpA, FadL and OmpW were down-regulated in kanamycin-resistant E. coli K-12 strain. Genetic deletion of tolC (ΔtolC-Km) led to a 2-fold decrease in the minimum inhibitory concentration (MIC) of kanamycin and deletion of mipA (ΔmipA-Km) resulted in a 4-fold increase in the MIC of kanamycin. Changes in the MICs for genetically modified strains could be completely recovered by gene complementation. Compared with the wild-type strain, the survival capability of ΔompA-Km was significantly increased and that of Δtsx-Km was significantly decreased. We further evaluated the role and expression of MipA in response to four other antibiotics including nalidixic acid, streptomycin, chloramphenicol and aureomycin, which suggested that MipA was a novel OM protein related to antibiotic resistance. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. Time-correlated transport of potassium ions through a thin poly-p-xylylene membrane

    International Nuclear Information System (INIS)

    Schroeck, Konstanze; Schulze, Susanne; Schlemmer, Andreas; Weitzel, Karl-Michael

    2010-01-01

    The transport of potassium ions through a 1 μm thick free-standing membrane of poly-para-xylylene (PPX) has been investigated under high vacuum conditions as a function of the impact energy of the potassium ions impinging onto the membrane. The experiment employs a c.w. potassium ion beam generated by thermionic emission from heated synthetic Leucite. Ions transmitted through the membrane are detected by a pair of microchannel plates detecting single particles. The analysis of the pulse-pair correlation function of successive ion detection events reveals a sharp drop in the width of the probability distribution between impact energies of 1300 and 1400 V. The maximum probability of the smallest waiting times exhibits a complementary increase. These variations are interpreted as an indication of a change in the underlying transport mechanism, most likely connected to a local electrical breakdown induced by pronounced space charge zones as a consequence of the ion bombardment. An upper limit for the relevant surface potential is discussed.

  17. Improving dynamic performance of proton-exchange membrane fuel cell system using time delay control

    Science.gov (United States)

    Kim, Young-Bae

    Transient behaviour is a key parameter for the vehicular application of proton-exchange membrane (PEM) fuel cell. The goal of this presentation is to construct better control technology to increase the dynamic performance of a PEM fuel cell. The PEM fuel cell model comprises a compressor, an injection pump, a humidifier, a cooler, inlet and outlet manifolds, and a membrane-electrode assembly. The model includes the dynamic states of current, voltage, relative humidity, stoichiometry of air and hydrogen, cathode and anode pressures, cathode and anode mass flow rates, and power. Anode recirculation is also included with the injection pump, as well as anode purging, for preventing anode flooding. A steady-state, isothermal analytical fuel cell model is constructed to analyze the mass transfer and water transportation in the membrane. In order to prevent the starvation of air and flooding in a PEM fuel cell, time delay control is suggested to regulate the optimum stoichiometry of oxygen and hydrogen, even when there are dynamical fluctuations of the required PEM fuel cell power. To prove the dynamical performance improvement of the present method, feed-forward control and Linear Quadratic Gaussian (LQG) control with a state estimator are compared. Matlab/Simulink simulation is performed to validate the proposed methodology to increase the dynamic performance of a PEM fuel cell system.

  18. Chlorine resistant desalination membranes based on directly sulfonated poly(arylene ether sulfone) copolymers

    Science.gov (United States)

    McGrath, James E [Blacksburg, VA; Park, Ho Bum [Austin, TX; Freeman, Benny D [Austin, TX

    2011-10-04

    The present invention provides a membrane, kit, and method of making a hydrophilic-hydrophobic random copolymer membrane. The hydrophilic-hydrophobic random copolymer membrane includes a hydrophilic-hydrophobic random copolymer. The hydrophilic-hydrophobic random copolymer includes one or more hydrophilic monomers having a sulfonated polyarylsulfone monomer and a second monomer and one or more hydrophobic monomers having a non-sulfonated third monomer and a fourth monomer. The sulfonated polyarylsulfone monomer introduces a sulfonate into the hydrophilic-hydrophobic random copolymer prior to polymerization.

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

    International Nuclear Information System (INIS)

    Zhao, Guili; Chen, Wei Ning

    2017-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-15

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

  1. Comparison and analysis of membrane fouling between flocculent sludge membrane bioreactor and granular sludge membrane bioreactor.

    Directory of Open Access Journals (Sweden)

    Wang Jing-Feng

    Full Text Available The goal of this study is to investigate the effect of inoculating granules on reducing membrane fouling. In order to evaluate the differences in performance between flocculent sludge and aerobic granular sludge in membrane reactors (MBRs, two reactors were run in parallel and various parameters related to membrane fouling were measured. The results indicated that specific resistance to the fouling layer was five times greater than that of mixed liquor sludge in the granular MBR. The floc sludge more easily formed a compact layer on the membrane surface, and increased membrane resistance. Specifically, the floc sludge had a higher moisture content, extracellular polymeric substances concentration, and negative surface charge. In contrast, aerobic granules could improve structural integrity and strength, which contributed to the preferable permeate performance. Therefore, inoculating aerobic granules in a MBR presents an effective method of reducing the membrane fouling associated with floc sludge the perspective of from the morphological characteristics of microbial aggregates.

  2. Time Average Holography Study of Human Tympanic Membrane with Altered Middle Ear Ossicular Chain

    Science.gov (United States)

    Cheng, Jeffrey T.; Ravicz, Michael E.; Rosowski, John J.; Hulli, Nesim; Hernandez-Montes, Maria S.; Furlong, Cosme

    2009-02-01

    Computer-assisted time average holographic interferometry was used to study the vibration of the human tympanic membrane (TM) in cadaveric temporal bones before and after alterations of the ossicular chain. Simultaneous laser Doppler vibrometer measurements of stapes velocity were performed to estimate the conductive hearing loss caused by ossicular alterations. The quantified TM motion described from holographic images was correlated with stapes velocity to define relations between TM motion and stapes velocity in various ossicular disorders. The results suggest that motions of the TM are relatively uncoupled from stapes motion at frequencies above 1000 Hz.

  3. Ultrastructure and lipid composition of detergent-resistant membranes derived from mammalian sperm and two types of epithelial cells.

    Science.gov (United States)

    van Gestel, Renske A; Brouwers, Jos F; Ultee, Anton; Helms, J Bernd; Gadella, Bart M

    2016-01-01

    Lipid rafts are micro-domains of ordered lipids (Lo phase) in biological membranes. The Lo phase of cellular membranes can be isolated from disordered lipids (Ld phase) after treatment with 1 % Triton  X-100 at 4 °C in which the Lo phase forms the detergent-resistant membrane (DRM) fraction. The lipid composition of DRM derived from Madin-Darby canine kidney (MDCK) cells, McArdle cells and porcine sperm is compared with that of the whole cell. Remarkably, the unsaturation and chain length degree of aliphatic chains attached to phospholipids is virtually the same between DRM and whole cells. Cholesterol and sphingomyelin were enriched in DRMs but to a cell-specific molar ratio. Sulfatides (sphingolipids from MDCK cells) were enriched in the DRM while a seminolipid (an alkylacylglycerolipid from sperm) was depleted from the DRM. Treatment with DRM without affecting the composition and amount of the phospholipid while higher levels disrupted the DRM. The substantial amount of (poly)unsaturated phospholipids in DRMs as well as a low stoichiometric amount of cholesterol suggest that lipid rafts in biological membranes are more fluid and dynamic than previously anticipated. Using negative staining, ultrastructural features of DRM were monitored and in all three cell types the DRMs appeared as multi-lamellar vesicular structures with a similar morphology. The detergent resistance is a result of protein-cholesterol and sphingolipid interactions allowing a relatively passive attraction of phospholipids to maintain the Lo phase. For this special issue, the relevance of our findings is discussed in a sperm physiological context.

  4. Preparation and performance of biofouling resistant PAN/chitosan hollow fiber membranes.

    Science.gov (United States)

    Shanthana Lakshmi, D; Jaiswar, Santlal; Saxena, Mayank; Tasselli, Franco; Raval, Hiren D

    2017-07-01

    The preparation of polyacrylonitrile (PAN) hollow fiber (HF) membranes has been carried out by dry-jet wet spinning. PAN HF membranes were coated with chitosan biopolymers 2 wt% by dip coating and further crosslinked by chemical reagents (Tri sodium polyphosphate). PAN HF (Virgin) and PAN/chitosan coated membrane were characterized by SEM and tested for water flux. Proteins Pepsin, Albumin, and Clay of 1000 ppm concentration were tested for separation efficiency. In addition, bacterial species Escherichia coli and Bacillus subtilis were tested for fouling control efficiency and found out that PAN/chitosan membranes were quite superior to virgin PAN fibers. The adhesion of bacterial cells on the surface of the hollow fiber membranes assessed through alcian blue staining and SEM analysis. It was observed that PAN/chitosan membranes (310A and 310C) possessed best antibacterial activities (based on SEM results), qualifying them as a very promising candidates for anti-biofouling coatings.

  5. Proton Conductive Channel Optimization in Methanol Resistive Hybrid Hyperbranched Polyamide Proton Exchange Membrane

    Directory of Open Access Journals (Sweden)

    Liying Ma

    2017-12-01

    Full Text Available Based on a previously developed polyamide proton conductive macromolecule, the nano-scale structure of the self-assembled proton conductive channels (PCCs is adjusted via enlarging the nano-scale pore size within the macromolecules. Hyperbranched polyamide macromolecules with different size are synthesized from different monomers to tune the nano-scale pore size within the macromolecules, and a series of hybrid membranes are prepared from these two micromoles to optimize the PCC structure in the proton exchange membrane. The optimized membrane exhibits methanol permeability low to 2.2 × 10−7 cm2/s, while the proton conductivity of the hybrid membrane can reach 0.25 S/cm at 80 °C, which was much higher than the value of the Nafion 117 membrane (0.192 S/cm. By considering the mechanical, dimensional, and the thermal properties, the hybrid hyperbranched polyamide proton exchange membrane (PEM exhibits promising application potential in direct methanol fuel cells (DMFC.

  6. Pulsed hydrogen/deuterium exchange mass spectrometry for time-resolved membrane protein folding studies.

    Science.gov (United States)

    Khanal, Anil; Pan, Yan; Brown, Leonid S; Konermann, Lars

    2012-12-01

    Kinetic folding experiments by pulsed hydrogen/deuterium exchange (HDX) mass spectrometry (MS) are a well-established tool for water-soluble proteins. To the best of our knowledge, the current study is the first that applies this approach to an integral membrane protein. The native state of bacteriorhodopsin (BR) comprises seven transmembrane helices and a covalently bound retinal cofactor. BR exposure to sodium dodecyl sulfate (SDS) induces partial unfolding and retinal loss. We employ a custom-built three-stage mixing device for pulsed-HDX/MS investigations of BR refolding. The reaction is triggered by mixing SDS-denatured protein with bicelles. After a variable folding time (10 ms to 24 h), the protein is exposed to excess D(2) O buffer under rapid exchange conditions. The HDX pulse is terminated by acid quenching after 24 ms. Subsequent off-line analysis is performed by size exclusion chromatography and electrospray MS. These measurements yield the number of protected backbone N-H sites as a function of folding time, reflecting the recovery of secondary structure. Our results indicate that much of the BR secondary structure is formed quite late during the reaction, on a time scale of 10 s and beyond. It is hoped that in the future it will be possible to extend the pulsed-HDX/MS approach employed here to membrane proteins other than BR. Copyright © 2012 John Wiley & Sons, Ltd.

  7. 4E10-resistant HIV-1 isolated from four subjects with rare membrane-proximal external region polymorphisms.

    Directory of Open Access Journals (Sweden)

    Kyle J Nakamura

    2010-03-01

    Full Text Available Human antibody 4E10 targets the highly conserved membrane-proximal external region (MPER of the HIV-1 transmembrane glycoprotein, gp41, and has extraordinarily broad neutralizing activity. It is considered by many to be a prototype for vaccine development. In this study, we describe four subjects infected with viruses carrying rare MPER polymorphisms associated with resistance to 4E10 neutralization. In one case resistant virus carrying a W680G substitution was transmitted from mother to infant. We used site-directed mutagenesis to demonstrate that the W680G substitution is necessary for conferring the 4E10-resistant phenotype, but that it is not sufficient to transfer the phenotype to a 4E10-sensitive Env. Our third subject carried Envs with a W680R substitution causing variable resistance to 4E10, indicating that residues outside the MPER are required to confer the phenotype. A fourth subject possessed a F673L substitution previously associated with 4E10 resistance. For all three subjects with W680 polymorphisms, we observed additional residues in the MPER that co-varied with position 680 and preserved charged distributions across this region. Our data provide important caveats for vaccine development targeting the MPER. Naturally occurring Env variants described in our study also represent unique tools for probing the structure-function of HIV-1 envelope.

  8. 4E10-resistant HIV-1 isolated from four subjects with rare membrane-proximal external region polymorphisms.

    Science.gov (United States)

    Nakamura, Kyle J; Gach, Johannes S; Jones, Laura; Semrau, Katherine; Walter, Jan; Bibollet-Ruche, Frederic; Decker, Julie M; Heath, Laura; Decker, William D; Sinkala, Moses; Kankasa, Chipepo; Thea, Donald; Mullins, James; Kuhn, Louise; Zwick, Michael B; Aldrovandi, Grace M

    2010-03-23

    Human antibody 4E10 targets the highly conserved membrane-proximal external region (MPER) of the HIV-1 transmembrane glycoprotein, gp41, and has extraordinarily broad neutralizing activity. It is considered by many to be a prototype for vaccine development. In this study, we describe four subjects infected with viruses carrying rare MPER polymorphisms associated with resistance to 4E10 neutralization. In one case resistant virus carrying a W680G substitution was transmitted from mother to infant. We used site-directed mutagenesis to demonstrate that the W680G substitution is necessary for conferring the 4E10-resistant phenotype, but that it is not sufficient to transfer the phenotype to a 4E10-sensitive Env. Our third subject carried Envs with a W680R substitution causing variable resistance to 4E10, indicating that residues outside the MPER are required to confer the phenotype. A fourth subject possessed a F673L substitution previously associated with 4E10 resistance. For all three subjects with W680 polymorphisms, we observed additional residues in the MPER that co-varied with position 680 and preserved charged distributions across this region. Our data provide important caveats for vaccine development targeting the MPER. Naturally occurring Env variants described in our study also represent unique tools for probing the structure-function of HIV-1 envelope.

  9. Effect of surface treatment on the interfacial contact resistance and corrosion resistance of Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Yang, Meijun; Zhang, Dongming

    2014-01-01

    The bipolar plate is an important component of the PEMFC (polymer electrolyte membrane fuel cell) because it supplies the pathway of electron flow between each unit cell. Fe–Ni–Cr alloy is considered as a good candidate material for bipolar plate, but it is limited to use as a bipolar plate due to its high ICR (interfacial contact resistance) and corrosion problem. In order to explore a cost-effective method on surface modification, various chemical and electrochemical treatments are performed on Fe–Ni–Cr alloy to acquire the effect of the surface modification on the ICR and corrosion behavior. The ICR and corrosion resistance of Fe–Ni–Cr alloy can be effectively controlled by the chemical treatment of immersion in the mixed acid solution with 10 vol% HNO 3 , 2 vol% HCl and 1 vol% HF for 10 min at 65 °C and then was placed in 30 vol% HNO 3 solution for 5 min. The chemical treatment is more effective on reducing ICR and improving corrosion resistance than that of electrochemical methods (be carried out in the 2 mol/L H 2 SO 4 solution with the electrical potential from −0.4 V to 0.6 V) for Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells. - Highlights: • The procedure of the surface treatments on Fe–Ni–Cr alloy as bipolar plate was described in detail. • Effects of various surface treatments on the interfacial contact resistivity and corrosion behavior were discussed. • The mechanism of the surface modification was particularly analyzed

  10. Trichoderma viride cellulase induces resistance to the antibiotic pore-forming peptide alamethicin associated with changes in the plasma membrane lipid composition of tobacco BY-2 cells

    Directory of Open Access Journals (Sweden)

    Andreasson Erik

    2010-12-01

    Full Text Available Abstract Background Alamethicin is a membrane-active peptide isolated from the beneficial root-colonising fungus Trichoderma viride. This peptide can insert into membranes to form voltage-dependent pores. We have previously shown that alamethicin efficiently permeabilises the plasma membrane, mitochondria and plastids of cultured plant cells. In the present investigation, tobacco cells (Nicotiana tabacum L. cv Bright Yellow-2 were pre-treated with elicitors of defence responses to study whether this would affect permeabilisation. Results Oxygen consumption experiments showed that added cellulase, already upon a limited cell wall digestion, induced a cellular resistance to alamethicin permeabilisation. This effect could not be elicited by xylanase or bacterial elicitors such as flg22 or elf18. The induction of alamethicin resistance was independent of novel protein synthesis. Also, the permeabilisation was unaffected by the membrane-depolarising agent FCCP. As judged by lipid analyses, isolated plasma membranes from cellulase-pretreated tobacco cells contained less negatively charged phospholipids (PS and PI, yet higher ratios of membrane lipid fatty acid to sterol and to protein, as compared to control membranes. Conclusion We suggest that altered membrane lipid composition as induced by cellulase activity may render the cells resistant to alamethicin. This induced resistance could reflect a natural process where the plant cells alter their sensitivity to membrane pore-forming agents secreted by Trichoderma spp. to attack other microorganisms, and thus adding to the beneficial effect that Trichoderma has for plant root growth. Furthermore, our data extends previous reports on artificial membranes on the importance of lipid packing and charge for alamethicin permeabilisation to in vivo conditions.

  11. Time-lapse resistivity surveys over simulated clandestine graves.

    Science.gov (United States)

    Jervis, John R; Pringle, Jamie K; Tuckwell, George W

    2009-11-20

    The aim of this study was to develop a better understanding of how electrical resistivity surveys can be used to locate clandestine graves. Resistivity surveys were conducted regularly over three simulated clandestine graves containing a pig cadaver, no cadaver and a pig cadaver wrapped in tarpaulin, respectively. Additionally, soil and groundwater samples were collected from two more simulated graves outside the survey area. The grave containing a pig cadaver was detectable from a low resistivity anomaly in the survey data. Groundwater data suggest that the resistivity anomaly associated with the surveyed pig grave was caused by a localised increase in groundwater conductivity. Wrapping a cadaver was found to initially change the resistivity response of a grave to a high resistivity anomaly. Resistivity surveys did not detect the disturbed soil in the grave that did not contain a cadaver. Although soil samples showed grave soil to be more porous than undisturbed soil, the lack of response from the grave that did not contain a cadaver suggests that disturbed soil was not responsible for the resistivity anomalies observed in this study. Resistivity surveys successfully detected all graves containing cadavers throughout the study, whilst also showing the potential to eliminate the need for mass excavation in a genuine search.

  12. Novel Swelling-Resistant Sodium Alginate Membrane Branching Modified by Glycogen for Highly Aqueous Ethanol Solution Pervaporation.

    Science.gov (United States)

    Ji, Chen-Hao; Xue, Shuang-Mei; Xu, Zhen-Liang

    2016-10-12

    A novel carbohydrate chain cross-linking method of sodium alginate (SA) is proposed in which glycogen with the branched-chain structure is utilized to cross-link with SA matrix by the bridging of glutaraldehyde (GA). The active layer of SA composite ceramic membrane modified by glycogen and GA for pervaporation (PV) demonstrates great advantages. The branched structure increases the chain density of the active layer, which compresses the free volume between the carbohydrate chains of SA. Large amounts of hydroxyl groups are consumed during the reaction with GA, which reduces the hydrogen bond formation between water molecules and the polysaccharide matrix. The two factors benefit the active layer with great improvement in swelling resistance, promoting the potential of the active layer for the dehydration of an ethanol-water solution containing high water content. Meanwhile, the modified active layer is loaded on the rigid α-Al 2 O 3 ceramic membrane by dip-coating method with the enhancement of anti-deformation and controllable thickness of the active layer. Characterization techniques such as SEM, AFM, XRD, FTIR, XPS, and water contact angle are utilized to observe the composite structure and surface morphology of the composite membrane, to probe the free volume variation, and to determine the chemical composition and hydrophilicity difference of the active layer caused by the different glycogen additive amounts. The membrane containing 3% glycogen in the selective layer demonstrates the flux at 1250 g m -2 h -1 coupled with the separation factor of 187 in the 25 wt % water content feed solution at the operating temperature of 75 °C, reflecting superior pervaporation processing capacity compared with the general organic PV membranes in the same condition.

  13. Cyclopropanation of unsaturated fatty acids and membrane rigidification improve the freeze-drying resistance of Lactococcus lactis subsp. lactis TOMSC161.

    Science.gov (United States)

    Velly, H; Bouix, M; Passot, S; Penicaud, C; Beinsteiner, H; Ghorbal, S; Lieben, P; Fonseca, F

    2015-01-01

    This work aimed at characterizing the biochemical and biophysical properties of the membrane of Lactococcus lactis TOMSC161 cells during fermentation at different temperatures, in relation to their freeze-drying and storage resistance. Cells were cultivated at two different temperatures (22 and 30 °C) and were harvested at different growth phases (from the middle exponential phase to the late stationary phase). Bacterial membranes were characterized by determining the fatty acid composition, the lipid phase transition, and the membrane fluidity. Cultivability and acidification activity losses of L. lactis were quantified after freezing, drying, and 3 months of storage. The direct measurement of membrane fluidity by fluorescence anisotropy was linked to lipid composition, and it was established that the cyclopropanation of unsaturated fatty acids with concomitant membrane rigidification during growth led to an increase in the freeze-drying and storage resistance of L. lactis. As expected, cultivating cells at a lower fermentation temperature than the optimum growth temperature induced a homeoviscous adaptation that was demonstrated by a lowered lipid phase transition temperature but that was not related to any improvement in freeze-drying resistance. L. lactis TOMSC161 was therefore able to develop a combined biochemical and biophysical response at the membrane level during fermentation. The ratio of cyclic fatty acids to unsaturated fatty acids (CFA/UFA) appeared to be the most relevant parameter associated with membrane rigidification and cell resistance to freeze-drying and storage. This study increased our knowledge about the physiological mechanisms that explain the resistance of lactic acid bacteria (LAB) to freeze-drying and storage stresses and demonstrated the relevance of complementary methods of membrane characterization.

  14. 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.

  15. Cycle-time determination and process control of sequencing batch membrane bioreactors.

    Science.gov (United States)

    Krampe, J

    2013-01-01

    In this paper a method to determine the cycle time for sequencing batch membrane bioreactors (SBMBRs) is introduced. One of the advantages of SBMBRs is the simplicity of adapting them to varying wastewater composition. The benefit of this flexibility can only be fully utilised if the cycle times are optimised for the specific inlet load conditions. This requires either proactive and ongoing operator adjustment or active predictive instrument-based control. Determination of the cycle times for conventional sequencing batch reactor (SBR) plants is usually based on experience. Due to the higher mixed liquor suspended solids concentrations in SBMBRs and the limited experience with their application, a new approach to calculate the cycle time had to be developed. Based on results from a semi-technical pilot plant, the paper presents an approach for calculating the cycle time in relation to the influent concentration according to the Activated Sludge Model No. 1 and the German HSG (Hochschulgruppe) Approach. The approach presented in this paper considers the increased solid contents in the reactor and the resultant shortened reaction times. This allows for an exact calculation of the nitrification and denitrification cycles with a tolerance of only a few minutes. Ultimately the same approach can be used for a predictive control strategy and for conventional SBR plants.

  16. Charge Transfer Resistance and Differential Capacity of the Plasticized PVC Membrane/Water Interface

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Stejskalová, Květoslava; Samec, Zdeněk

    2002-01-01

    Roč. 521, 1/2 (2002), s. 81-86 ISSN 0022-0728 R&D Projects: GA AV ČR IAA4040902 Institutional research plan: CEZ:AV0Z4040901 Keywords : impedance * PVC plasticized membrane * ion transfer kinetics Subject RIV: CG - Electrochemistry Impact factor: 2.027, year: 2002

  17. Membrane-bound ATPase contributes to hop resistance of Lactobacillus brevis

    NARCIS (Netherlands)

    Sakamoto, K; van Veen, HW; Saito, H; Kobayashi, H; Konings, WN

    2002-01-01

    The activity of the membrane-bound H+-ATPase of the beer spoilage bacterium Lactobacillus brevis ABBC45 increased upon adaptation to bacteriostatic hop compounds. The ATPase activity was optimal around pH 5.6 and increased up to fourfold when L. brevis was exposed to 666 muM hop compounds. The

  18. Functional activity of Gi alpha protein in detergent resistant membrane domains from rat brain cortex

    Czech Academy of Sciences Publication Activity Database

    Stöhr, Jiří; Rudajev, Vladimír; Bouřová, Lenka; Lisý, Václav; Novotný, Jiří; Svoboda, Petr

    2007-01-01

    Roč. 101, Suppl.1 (2007), s. 52-52 ISSN 0022-3042. [European Society for Neurochemistry Meeting /17./. 19.05.2007-22.05.2007, Salamanca] Institutional research plan: CEZ:AV0Z50110509 Keywords : cpo1 * GABAB receptor * Gi protein * membrane domains Subject RIV: ED - Physiology

  19. The Experimental Measurement of Local and Bulk Oxygen Transport Resistances in the Catalyst Layer of Proton Exchange Membrane Fuel Cells.

    Science.gov (United States)

    Wang, Chao; Cheng, Xiaojing; Lu, Jiabin; Shen, Shuiyun; Yan, Xiaohui; Yin, Jiewei; Wei, Guanghua; Zhang, Junliang

    2017-12-07

    Remarkable progress has been made in reducing the cathodic Pt loading of PEMFCs; however, a huge performance loss appears at high current densities, indicating the existence of a large oxygen transport resistance associated with the ultralow Pt loading catalyst layer. To reduce the Pt loading without sacrificing cell performance, it is essential to illuminate the oxygen transport mechanism in the catalyst layer. Toward this goal, an experimental approach to measure the oxygen transport resistance in catalyst layers is proposed and realized for the first time in this study. The measuring approach involves a dual-layer catalyst layer design, which consists of a dummy catalyst layer and a practical catalyst layer, followed by changing the thickness of dummy layer to respectively quantify the local and bulk resistances via limiting current measurements combined with linear extrapolation. The experimental results clearly reveal that the local resistance dominates the total resistance in the catalyst layer.

  20. Proteomic Analysis of Detergent Resistant Membrane Domains during Early Interaction of Macrophages with Rough and Smooth Brucella melitensis

    Science.gov (United States)

    Lauer, Sabine A.; Iyer, Srinivas; Sanchez, Timothy; Forst, Christian V.; Bowden, Brent; Carlson, Kay; Sriranganathan, Nammalwar; Boyle, Stephen M.

    2014-01-01

    The plasma membrane contains discrete nanometer-sized domains that are resistant to non-ionic detergents, and which are called detergent resistant membrane domains (DRMDs) or lipid rafts. Exposure of host cells to pathogenic bacteria has been shown to induce the re-distribution of specific host proteins between DRMDs and detergent soluble membranes, which leads to the initiation of cell signaling that enable pathogens to access host cells. DRMDs have been shown to play a role in the invasion of Brucella into host macrophages and the formation of replicative phagosomes called Brucella-containing vacuoles (BCVs). In this study we sought to characterize changes to the protein expression profiles in DRMDs and to respective cellular pathways and networks of Mono Mac 6 cells in response to the adherence of rough VTRM1 and smooth 16 M B. melitensis strains. DRMDs were extracted from Mono Mac 6 cells exposed for 2 minutes at 4°C to Brucella (no infection occurs) and from unexposed control cells. Protein expression was determined using the non-gel based quantitative iTRAQ (Isobaric Tags for Relative and Absolute Quantitation) mass spectrometry technique. Using the identified iTRAQ proteins we performed enrichment analyses and probed constructed human biochemical networks for interactions and metabolic reactions. We identified 149 proteins, which either became enriched, depleted or whose amounts did not change in DRMDs upon Brucella exposure. Several of these proteins were distinctly enriched or depleted in DRMDs upon exposure to rough and smooth B. melitensis strains which results in the differential engagement of cellular pathways and networks immediately upon Brucella encounter. For some of the proteins such as myosin 9, small G protein signaling modulator 3, lysine-specific demethylase 5D, erlin-2, and voltage-dependent anion-selective channel protein 2, we observed extreme differential depletion or enrichment in DRMDs. The identified proteins and pathways could provide

  1. Total internal reflection fluorescence (TIRF) microscopy for real-time imaging of nanoparticle-cell plasma membrane interaction

    DEFF Research Database (Denmark)

    Parhamifar, Ladan; Moghimi, Seyed Moien

    2012-01-01

    fluorescence (TIRF) microscopy allows for real-time monitoring of nanoparticle-membrane interaction events, which can provide vital information in relation to design and surface engineering of therapeutic nanoparticles for cell-specific targeting. In contrast to other microscopy techniques, the bleaching...... effect by lasers in TIRF microscopy is considerably less when using fluorescent nanoparticles and it reduces photo-induced cytotoxicity during visualization of live-cell events since it only illuminates the specific area near or at the plasma membrane....

  2. Optimization of Hydraulic Retention Time and Biomass Concentration in Microalgae Biomass Production from Treated Sewage with a Membrane Photobioreactor

    OpenAIRE

    Honda, Ryo; Teraoka, Yuta; Noguchi, Mana; Yang, Sen

    2017-01-01

    Treated sewage is a promising source of nitrogen and phosphorus in microalgae biomass production for carbon-neutral biofuel and chemical products. In this study, Chlorella vulgaris was continuously cultivated in membrane photobioreactors (MPBRs) under short hydraulic retention times (HRTs) and with different numbers of submerged membrane modules to investigate potential microalgae productivity when treated sewage was used as a nutrient source. Microalgae biomass concentrations were independen...

  3. Arabidopsis Novel Glycine-Rich Plasma Membrane PSS1 Protein Enhances Disease Resistance in Transgenic Soybean Plants1[OPEN

    Science.gov (United States)

    Wang, Bing; Sumit, Rishi; Srivastava, Subodh K.; Yang, Yang; Swaminathan, Sivakumar

    2018-01-01

    Nonhost resistance is defined as the immunity of a plant species to all nonadapted pathogen species. Arabidopsis (Arabidopsis thaliana) ecotype Columbia-0 is nonhost to the oomycete plant pathogen Phytophthora sojae and the fungal plant pathogen Fusarium virguliforme that are pathogenic to soybean (Glycine max). Previously, we reported generating the pss1 mutation in the pen1-1 genetic background as well as genetic mapping and characterization of the Arabidopsis nonhost resistance Phytophthora sojae-susceptible gene locus, PSS1. In this study, we identified six candidate PSS1 genes by comparing single-nucleotide polymorphisms of (1) the bulked DNA sample of seven F2:3 families homozygous for the pss1 allele and (2) the pen1-1 mutant with Columbia-0. Analyses of T-DNA insertion mutants for each of these candidate PSS1 genes identified the At3g59640 gene encoding a glycine-rich protein as the putative PSS1 gene. Later, complementation analysis confirmed the identity of At3g59640 as the PSS1 gene. PSS1 is induced following P. sojae infection as well as expressed in an organ-specific manner. Coexpression analysis of the available transcriptomic data followed by reverse transcriptase-polymerase chain reaction suggested that PSS1 is coregulated with ATG8a (At4g21980), a core gene in autophagy. PSS1 contains a predicted single membrane-spanning domain. Subcellular localization study indicated that it is an integral plasma membrane protein. Sequence analysis suggested that soybean is unlikely to contain a PSS1-like defense function. Following the introduction of PSS1 into the soybean cultivar Williams 82, the transgenic plants exhibited enhanced resistance to F. virguliforme, the pathogen that causes sudden death syndrome. PMID:29101280

  4. Growth cone travel in space and time: the cellular ensemble of cytoskeleton, adhesion, and membrane.

    Science.gov (United States)

    Vitriol, Eric A; Zheng, James Q

    2012-03-22

    Growth cones, found at the tip of axonal projections, are the sensory and motile organelles of developing neurons that enable axon pathfinding and target recognition for precise wiring of the neural circuitry. To date, many families of conserved guidance molecules and their corresponding receptors have been identified that work in space and time to ensure billions of axons to reach their targets. Research in the past two decades has also gained significant insight into the ways in which growth cones translate extracellular signals into directional migration. This review aims to examine new progress toward understanding the cellular mechanisms underlying directional motility of the growth cone and to discuss questions that remain to be addressed. Specifically, we will focus on the cellular ensemble of cytoskeleton, adhesion, and membrane and examine how the intricate interplay between these processes orchestrates the directed movement of growth cones. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Comparing and Contrasting Traditional Membrane Bioreactor Models with Novel Ones Based on Time Series Analysis

    Directory of Open Access Journals (Sweden)

    Parneet Paul

    2013-02-01

    Full Text Available The computer modelling and simulation of wastewater treatment plant and their specific technologies, such as membrane bioreactors (MBRs, are becoming increasingly useful to consultant engineers when designing, upgrading, retrofitting, operating and controlling these plant. This research uses traditional phenomenological mechanistic models based on MBR filtration and biochemical processes to measure the effectiveness of alternative and novel time series models based upon input–output system identification methods. Both model types are calibrated and validated using similar plant layouts and data sets derived for this purpose. Results prove that although both approaches have their advantages, they also have specific disadvantages as well. In conclusion, the MBR plant designer and/or operator who wishes to use good quality, calibrated models to gain a better understanding of their process, should carefully consider which model type is selected based upon on what their initial modelling objectives are. Each situation usually proves unique.

  6. Real time optimization of solar powered direct contact membrane distillation based on multivariable extremum seeking

    KAUST Repository

    Karam, Ayman M.

    2015-09-21

    This paper presents a real time optimization scheme for a solar powered direct contact membrane distillation (DCMD) water desalination system. The sun and weather conditions vary and are inconsistent throughout the day. Therefore, the solar powered DCMD feed inlet temperature is never constant, which influences the distilled water flux. The problem of DCMD process optimization has not been studied enough. In this work, the response of the process under various feed inlet temperatures is investigated, which demonstrates the need for an optimal controller. To address this issue, we propose a multivariable Newton-based extremum seeking controller which optimizes the inlet feed and permeate mass flow rates as the feed inlet temperature varies. Results are presented and discussed for a realistic temperature profile.

  7. Disruption of Mitochondria-Associated Endoplasmic Reticulum Membrane (MAM) Integrity Contributes to Muscle Insulin Resistance in Mice and Humans.

    Science.gov (United States)

    Tubbs, Emily; Chanon, Stéphanie; Robert, Maud; Bendridi, Nadia; Bidaux, Gabriel; Chauvin, Marie-Agnès; Ji-Cao, Jingwei; Durand, Christine; Gauvrit-Ramette, Daphné; Vidal, Hubert; Lefai, Etienne; Rieusset, Jennifer

    2018-04-01

    Modifications of the interactions between endoplasmic reticulum (ER) and mitochondria, defined as mitochondria-associated membranes (MAMs), were recently shown to be involved in the control of hepatic insulin action and glucose homeostasis, but with conflicting results. Whereas skeletal muscle is the primary site of insulin-mediated glucose uptake and the main target for alterations in insulin-resistant states, the relevance of MAM integrity in muscle insulin resistance is unknown. Deciphering the importance of MAMs on muscle insulin signaling could help to clarify this controversy. Here, we show in skeletal muscle of different mice models of obesity and type 2 diabetes (T2D) a marked disruption of ER-mitochondria interactions as an early event preceding mitochondrial dysfunction and insulin resistance. Furthermore, in human myotubes, palmitate-induced insulin resistance is associated with a reduction of structural and functional ER-mitochondria interactions. Importantly, experimental increase of ER-mitochondria contacts in human myotubes prevents palmitate-induced alterations of insulin signaling and action, whereas disruption of MAM integrity alters the action of the hormone. Lastly, we found an association between altered insulin signaling and ER-mitochondria interactions in human myotubes from obese subjects with or without T2D compared with healthy lean subjects. Collectively, our data reveal a new role of MAM integrity in insulin action of skeletal muscle and highlight MAM disruption as an essential subcellular alteration associated with muscle insulin resistance in mice and humans. Therefore, reduced ER-mitochondria coupling could be a common alteration of several insulin-sensitive tissues playing a key role in altered glucose homeostasis in the context of obesity and T2D. © 2018 by the American Diabetes Association.

  8. Robust aqua material. A pressure-resistant self-assembled membrane for water purification

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Erez; Weissman, Haim; Rybtchinski, Boris [Department of Organic Chemistry, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Shimoni, Eyal; Kaplan-Ashiri, Ifat [Department of Chemical Research Support, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Werle, Kai; Wohlleben, Wendel [Department of Material Physics, Materials and Systems Research, BASF SE, 67056, Ludwigshafen (Germany)

    2017-02-13

    ''Aqua materials'' that contain water as their major component and are as robust as conventional plastics are highly desirable. Yet, the ability of such systems to withstand harsh conditions, for example, high pressures typical of industrial applications has not been demonstrated. We show that a hydrogel-like membrane self-assembled from an aromatic amphiphile and colloidal Nafion is capable of purifying water from organic molecules, including pharmaceuticals, and heavy metals in a very wide range of concentrations. Remarkably, the membrane can sustain high pressures, retaining its function. The robustness and functionality of the water-based self-assembled array advances the idea that aqua materials can be very strong and suitable for demanding industrial applications. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Cross-Linkable Polyimide Membranes for Improved Plasticization Resistance and Permselectivity in Sour Gas Separations

    KAUST Repository

    Kraftschik, Brian

    2013-09-10

    A series of cross-linkable membrane materials based on the 6FDA-DAM:DABA (3:2) polyimide backbone were synthesized for improved sour gas separation performance, in terms of both membrane stability and permselectivity. Short-chain poly(ethylene glycol) (PEG) molecules were used as cross-linking agents in an esterification-based cross-linking reaction. Pure and mixed gas permeation and pure gas sorption experiments were performed on dense films of these materials. Compared to unmodified 6FDA-DAM:DABA (3:2), higher sour gas permselectivity and membrane stability were achieved under aggressive feed conditions. H2S-induced plasticization was not evident until pure H2S feed pressures greater than approximately 6-8 bar. Pure CO 2-induced plasticization only occurred at feed pressures greater than about 25 bar. Under mixed gas feed conditions with 20% H2S, 20% CO2, and 60% CH4 at 35 C, attractive selectivities above 22 and 27 for H2S/CH4 and CO2/CH4, respectively, were observed for a feed pressure of 62 bar with both triethylene glycol and tetraethylene glycol cross-linking agents. © 2013 American Chemical Society.

  10. Prediction of antibiotic resistance: time for a new preclinical paradigm?

    DEFF Research Database (Denmark)

    Sommer, Morten Otto Alexander; Munck, Christian; Toft-Kehler, Rasmus Vendler

    2017-01-01

    Predicting the future is difficult, especially for evolutionary processes that are influenced by numerous unknown factors. Still, this is what is required of drug developers when they assess the risk of resistance arising against a new antibiotic candidate during preclinical development....... In this Opinion article, we argue that the traditional procedures that are used for the prediction of antibiotic resistance today could be markedly improved by including a broader analysis of bacterial fitness, infection dynamics, horizontal gene transfer and other factors. This will lead to more informed...

  11. Cholesterol sensitivity of detergent resistance: A rapid flow cytometric test for detecting constitutive or induced raft association of membrane proteins

    OpenAIRE

    Imre Gombos, Zsolt Bacsó, Cynthia Detre, Henrietta Nagy, Katalin Goda, Márton Andrásfalvy, Gábor Szabó, János Matkó; Bacsó Zsolt (1963-) (biofizikus); Goda Katalin (1969-) (biofizikus); Szabó Gábor (1953-) (biofizikus)

    2004-01-01

    Lipid rafts are cholesterol- and glycosphingolipid-rich microdomains in the cellular plasma membranes that play critical roles in compartmentalization (concentration, coupling, and isolation) of receptors and signal molecules. Therefore, detecting constitutive or induced raft associations of such proteins is of central interest in cell biology. This has mostly been done with time- and cell-consuming immunobiochemical techniques affected by several sources of artifacts. A flow cytometric analy...

  12. Disruption of the mitochondria-associated ER membrane (MAM) plays a central role in palmitic acid-induced insulin resistance.

    Science.gov (United States)

    Shinjo, Satoko; Jiang, Shuying; Nameta, Masaaki; Suzuki, Tomohiro; Kanai, Mai; Nomura, Yuta; Goda, Nobuhito

    2017-10-01

    The mitochondria-associated ER membrane (MAM) is a specialized subdomain of ER that physically connects with mitochondria. Although disruption of inter-organellar crosstalk via the MAM impairs cellular homeostasis, its pathological significance in insulin resistance in type 2 diabetes mellitus remains unclear. Here, we reveal the importance of reduced MAM formation in the induction of fatty acid-evoked insulin resistance in hepatocytes. Palmitic acid (PA) repressed insulin-stimulated Akt phosphorylation in HepG2 cells within 12h. Treatment with an inhibitor of the ER stress response failed to restore PA-mediated suppression of Akt activation. Mitochondrial reactive oxygen species (ROS) production did not increase in PA-treated cells. Even short-term exposure (3h) to PA reduced the calcium flux from ER to mitochondria, followed by a significant decrease in MAM contact area, suggesting that PA suppressed the functional interaction between ER and mitochondria. Forced expression of mitofusin-2, a critical component of the MAM, partially restored MAM contact area and ameliorated the PA-elicited suppression of insulin sensitivity with Ser473 phosphorylation of Akt selectively improved. These results suggest that loss of proximity between ER and mitochondria, but not perturbation of homeostasis in the two organelles individually, plays crucial roles in PA-evoked Akt inactivation in hepatic insulin resistance. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Time-resolved GISAXS and cryo-microscopy characterization of block copolymer membrane formation

    KAUST Repository

    Marques, Debora S.

    2014-03-01

    Time-resolved grazing-incidence small-angle X-ray scattering (GISAXS) and cryo-microscopy were used for the first time to understand the pore evolution by copolymer assembly, leading to the formation of isoporous membranes with exceptional porosity and regularity. The formation of copolymer micelle strings in solution (in DMF/DOX/THF and DMF/DOX) was confirmed by cryo field emission scanning electron microscopy (cryo-FESEM) with a distance of 72 nm between centers of micelles placed in different strings. SAXS measurement of block copolymer solutions in DMF/DOX indicated hexagonal assembly with micelle-to-micelle distance of 84-87 nm for 14-20 wt% copolymer solutions. GISAXS in-plane peaks were detected, revealing order close to hexagonal. The d-spacing corresponding to the first peak in this case was 100-130 nm (lattice constant 115-150 nm) for 17 wt% copolymer solutions evaporating up to 100 s. Time-resolved cryo-FESEM showed the formation of incipient pores on the film surface after 4 s copolymer solution casting with distances between void centers of 125 nm. © 2014 Elsevier Ltd. All rights reserved.

  14. Membrane introduction/laser photoionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Oser, Harald; Coggiola, Michael J; Young, Steven E; Crosley, David R; Hafer, Virginia; Grist, Gregory

    2007-04-01

    Two-photon resonance enhanced multiphoton ionization (REMPI) has been shown to be a unique ionization method for mass spectrometry, exhibiting both high sensitivity and chemical selectivity. Because REMPI is a gas-phase method, its applications have been limited either to direct analysis of vapor phase samples, or in conjunction with an initial laser desorption or other vaporization step. We describe here for the first time a combination of membrane introduction mass spectrometry (MIMS) and REMPI with time-of-flight mass spectrometry (TOF-MS), which allows for the direct analysis of trace amounts of organic compounds in water samples. The objective of our research was the detection of very low levels of aromatic contaminants, particularly benzene, toluene, and xylene (BTX), in aqueous solutions without interference due to the water. We have measured limits of detection (LOD) for selected aromatics in water below 1 part-per-trillion with an averaging time of less than 10 s using a continuous sample flow.

  15. Spectral versus time-domain OCT in detecting preoperative epiretinal membranes that accompany macular holes.

    Science.gov (United States)

    Rao, Prethy; Yonekawa, Yoshihiro; Thomas, Benjamin J; Drenser, Kimberly A

    2017-03-10

    To compare the sensitivities of spectral-domain optical coherence tomography (SD-OCT) versus time-domain OCT (TD-OCT) in identifying epiretinal membranes (ERM) preoperatively in patients who underwent surgery for full-thickness macular holes (FTMH). This is an interventional retrospective case series of 59 eyes diagnosed with FTMHs who underwent 25-G pars plana vitrectomy with internal limiting membrane peeling between 2009 and 2015. Preoperative OCTs were obtained by SD-OCT (Spectralis, Heidelberg, Germany) or TD-OCT (Stratus, Carl Zeiss Meditec, Dublin, CA, USA). Volume scans were reviewed for ERM accompanying the FTMH. This was compared to indocyanine green-negative staining and intraoperative findings of ERM as the gold standard. Baseline characteristics between the SD-OCT and TD-OCT groups were comparable. Mean duration of postoperative follow-up was 41.4 weeks (±49.0). Of 59 eyes, 33 (55.9%) exhibited an ERM intraoperatively. Four ERMs (SD-OCT group) compared to 12 (TD-OCT group) were not visualized on preoperative OCT (p = 0.003). Sensitivity and specificity of SD-OCT in ERM detection was 79% and 100% compared to 14% and 91% for TD-OCT. Visual acuity improved in both arms (0.5 and 0.3 logMAR units in SD-OCT and TD-OCT, respectively (p = 0.002, 0.0002). We found that SD-OCT was superior to TD-OCT in identifying the presence of ERM preoperatively in patients who underwent macular hole surgery. Since ERMs may decrease the chance of successful pharmacologic vitreolysis, we recommend using SD-OCT over TD-OCT in the evaluation of patients with FTMH to more accurately identify ERMs and allow more comprehensive treatment decisions (pharmacologic versus surgical).

  16. Effect of growth times on the physical and mechanical properties of hydrophobic and oleophilic silylated bacterial cellulose membranes

    Science.gov (United States)

    Zakaria, M. N.; Sukirah, A. R.; Maizatulnisa, O.; Ayuni, J.; Khalisanni, K.; Rosmamuhamadani, R.

    2017-09-01

    Bacterial cellulose is an extracellular natural byproduct of the metabolism of various bacteria. Its physical and mechanical properties were determined by growth period, method of cultivation either static or agitate, fermentation condition and medium. Thispaper presented works done on the effect of culture time on the physical and mechanical properties of silylated bacteria cellulose membranes. Bacterial cellulose (BC) growth under 4, 5, 6 and 7 days had been used as a natural reinforcement material and silane as a hydrophobic coating material. With extended culture time, the tensile strength and tensile modulus were increased linearly as result of more compact structure. Due to hydrophobic properties of silane, the water absorption and thickness swelling improved correspondingly. Contact angle testingusing three different liquid proven the functionality of silane as hydrophobic and oleophilic coating agent. The experimental results suggested that hydropobicand oleophilicsilylatedbacteria cellulose membranes with controlled growth time could be prepared and regarded as a reusable oil spills membrane.

  17. Identifying the components in eggshell membrane responsible for reducing the heat resistance of bacterial pathogens.

    Science.gov (United States)

    Ahlborn, Gene; Sheldon, Brian W

    2006-04-01

    The biological activity (D-value determination) of eggshell membrane (ESM) was examined to determine the membrane components and mechanisms responsible for antibacterial activity. Biological and enzymatic activities (i.e., beta-N-acetylglucosaminidase [beta-NAGase], lysozyme, and ovotransferrin) of ESM denatured with trypsin, lipases, or heat were compared with those of untreated ESM. Trypsin-treated ESM lost all biological activity (D-values at 54 degrees C were 5.12 and 5.38 min for immobilized and solubilized trypsin, respectively) but showed no significant loss of enzymatic activities. Treatments with porcine lipase and a lipase cocktail did not impact biological or enzymatic activities. Heat denaturation of ESM (at 80 and 100 degrees C for 15 min) resulted in significant decreases in biological activity (D-values of 3.99 and 4.43 min, respectively) and loss of beta-NAGase activity. Lysozyme and ovotransferrin activities remained but were significantly reduced. Purified ESM and hen egg white components (i.e., beta-NAGase, lysozyme, and ovotransferrin) were added to Salmonella Typhimurium suspensions (in 0.1% peptone water) at varying concentrations to evaluate their biological activity. D-values at 54 degrees C were 4.50 and 3.68 min for treatment with lysozyme or beta-NAGase alone, respectively, and 2.44 min for ovotransferrin but 1.47 min for a combination of all three components (similar to values for ESM). Exposure of Salmonella Typhimurium cells to a mixture of ovotransferrin, lysozyme, and beta-NAGase or ESM resulted in significant increases in extracellular concentrations of Ca2+, Mg2+, and K+. Transmission electron microscopic examination of Salmonella Typhimurium cells treated with a combination of ovotransferrin, lysozyme, and beta-NAGase revealed membrane disruption and cell lysis. The findings of this study demonstrate that ovotransferrin, lysozyme, and beta-NAGase are the primary components responsible for ESM antibacterial activity. The

  18. Metastatic castration-resistant prostate cancer: time for innovation.

    Science.gov (United States)

    Tucci, Marcello; Scagliotti, Giorgio Vittorio; Vignani, Francesca

    2015-01-01

    Androgen deprivation is the mainstay of advanced prostate cancer treatment. Despite initial responses, almost all patients progress to castration-resistant prostate cancer (CRPC). The understanding of the biology of CRPC and the evidence that CRPC still remains driven by androgen receptor signaling led to the discovery of new therapeutic targets. In the last few years, large Phase III trials showed improvements in survival and outcomes and led to the approval of a CYP17 inhibitor (abiraterone), an androgen receptor antagonist (enzalutamide), the taxane cabazitaxel, an α-emitter (radium-223), the bone resorption-targeting drug denosumab and an immunotherapy (sipuleucel-T). This article describes the molecular mechanisms underlying castration resistance, discusses recent and ongoing trials and offers some insights into identifying the best sequence of new drugs.

  19. Alterations in Outer Membrane Permeability Favor Drug-Resistant Phenotype of Klebsiella pneumoniae

    Czech Academy of Sciences Publication Activity Database

    Pulzová, L.; Navrátilová, Lucie; Comor, L.

    2017-01-01

    Roč. 23, č. 4 (2017), s. 413-420 ISSN 1076-6294 Institutional support: RVO:61389030 Keywords : drug resistance * efflux pumps * influx * Klebsiella * porin Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.306, year: 2016

  20. Single mutation confers vanadate resistance to the plasma membrane H+-ATPase from the yeast Schizosaccharomyces pombe

    International Nuclear Information System (INIS)

    Ulaszewski, S.; Van Herck, J.C.; Dufour, J.P.; Kulpa, J.; Nieuwenhuis, B.; Goffeau, A.

    1987-01-01

    A single-gene nuclear mutant has been selected from the yeast Schizosaccharomyces pombe for growth resistance to Dio-9, a plasma membrane H+-ATPase inhibitor. From this mutant, called pma1, an ATPase activity has been purified. It contains a Mr = 100,000 major polypeptide which is phosphorylated by [gamma- 32 P] ATP. Proton pumping is not impaired since the isolated mutant ATPase is able, in reconstituted proteoliposomes, to quench the fluorescence of the delta pH probe 9-amino-6-chloro-2-methoxy acridine. The isolated mutant ATPase is sensitive to Dio-9 as well as to seven other plasma membrane H+-ATPase inhibitors. The mutant H+-ATPase activity tested in vitro is, however, insensitive to vanadate. Its Km for MgATP is modified and its ATPase specific activity is decreased. The pma1 mutation decreases the rate of extracellular acidification induced by glucose when cells are incubated at pH 4.5 under nongrowing conditions. During growth, the intracellular mutant pH is more acid than the wild type one. The derepression by ammonia starvation of methionine transport is decreased in the mutant. The growth rate of pma1 mutants is reduced in minimal medium compared to rich medium, especially when combined to an auxotrophic mutation. It is concluded that the H+-ATPase activity from yeast plasma membranes controls the intracellular pH as well as the derepression of amino acid, purine, and pyrimidine uptakes. The pma1 mutation modifies several transport properties of the cells including those responsible for the uptake of Dio-9 and other inhibitors

  1. A novel action of deltamethrin on membrane resistance in mammalian skeletal muscle and non-myelinated nerve fibres.

    Science.gov (United States)

    Forshaw, P J; Ray, D E

    1990-01-01

    The pyrethroids, deltamethrin and cismethrin, were assessed for their ability to change membrane conductance directly in skeletal muscle and indirectly in non-myelinated nerve fibre preparations from the rat. In diaphragm muscle fibres of the rat, input resistance was significantly increased (35%) by deltamethrin but not by cismethrin, compared with solvent alone. In perfused vagus nerve from the rat, the amplitude of the post-tetanic hyperpolarization was significantly increased (100%) by deltamethrin both in vitro and ex vivo but not by cismethrin or solvent. In both test systems the actions of deltamethrin were abolished by changing the perfusate to a low chloride solution. The enhancement of amplitude of post-tetanic hyperpolarization by deltamethrin was reversed by ivermectin, a compound known to increase the resting chloride flux in neuronal preparations. Depolarizing afterpotentials, indicative of a prolongation in sodium conductance, did not develop until 0.5-1.0 hr after the enhancement of the amplitude of post-tetanic hyperpolarization by deltamethrin in the vagus preparations. The amplitude of post-tetanic hyperpolarization was not enhanced by exposure of the vagus to veratrine. These observations reinforce the conclusion that the enhancement of post-tetanic hyperpolarization by deltamethrin is not the result of intracellular accumulation of sodium. In addition, the chloride-dependent nature of the effects of deltamethrin, in both muscle and non-myelinated nerve, suggests that they are in both cases due to a reduction in resting membrane chloride conductance. This novel action of deltamethrin would be expected to amplify the effect of prolonged sodium current and thus influence the actions on excitable membranes both directly and indirectly.

  2. Differential Adaptations of Methicillin-Resistant Staphylococcus aureus to Serial In Vitro Passage in Daptomycin: Evolution of Daptomycin Resistance and Role of Membrane Carotenoid Content and Fluidity

    Directory of Open Access Journals (Sweden)

    Nagendra N. Mishra

    2012-01-01

    Full Text Available Previous studies showed serial 20 d in vitro passage of MRSA strain MW2 in sublethal daptomycin (DAP resulted in diverse perturbations in both cell membrane (CM and cell wall (CW characteristics, including increased CM rigidity; increased CW thickness; “gain-in-function” single nucleotide polymorphisms (SNPs in the mprF locus (i.e., increased synthesis and translocation of lysyl-phosphatidylglycerol (L-PG; progressive accumulation of SNPs in yyc and rpo locus genes; reduced carotenoid production; cross-resistance to innate host defense peptides. The current study was designed to characterize the reproducibility of these phenotypic and genotypic modifications following in vitro serial passages of the same parental strain. After a second 20d serial in vitro passage of parental MW2, emergence of DAP-R was associated with evolution of several phenotypes closely mirroring previous passage outcomes. However, in contrast to the initial serial passage strain set, we observed (i only modest increase in L-PG synthesis and no increase in L-PG outer CM translocation; (ii significantly increased carotenoid synthesis (P<0.05; (iii a different order of SNP accumulations (mprF≫rpoB≫yycG; (iv a different cadre and locations of such SNPs. Thus, MRSA strains are not “pre-programmed” to phenotypically and/or genotypically adapt in an identical manner during induction of DAP resistance.

  3. Resistance of Yersinia pestis to Complement-Dependent Killing Is Mediated by the Ail Outer Membrane Protein▿

    Science.gov (United States)

    Bartra, Sara Schesser; Styer, Katie L.; O'Bryant, Deanna M.; Nilles, Matthew L.; Hinnebusch, B. Joseph; Aballay, Alejandro; Plano, Gregory V.

    2008-01-01

    Yersinia pestis, the causative agent of plague, must survive in blood in order to cause disease and to be transmitted from host to host by fleas. Members of the Ail/Lom family of outer membrane proteins provide protection from complement-dependent killing for a number of pathogenic bacteria. The Y. pestis KIM genome is predicted to encode four Ail/Lom family proteins. Y. pestis mutants specifically deficient in expression of each of these proteins were constructed using lambda Red-mediated recombination. The Ail outer membrane protein was essential for Y. pestis to resist complement-mediated killing at 26 and 37°C. Ail was expressed at high levels at both 26 and 37°C, but not at 6°C. Expression of Ail in Escherichia coli provided protection from the bactericidal activity of complement. High-level expression of the three other Y. pestis Ail/Lom family proteins (the y1682, y2034, and y2446 proteins) provided no protection against complement-mediated bacterial killing. A Y. pestis ail deletion mutant was rapidly killed by sera obtained from all mammals tested except mouse serum. The role of Ail in infection of mice, Caenorhabditis elegans, and fleas was investigated. PMID:18025094

  4. Resistance of Yersinia pestis to complement-dependent killing is mediated by the Ail outer membrane protein.

    Science.gov (United States)

    Bartra, Sara Schesser; Styer, Katie L; O'Bryant, Deanna M; Nilles, Matthew L; Hinnebusch, B Joseph; Aballay, Alejandro; Plano, Gregory V

    2008-02-01

    Yersinia pestis, the causative agent of plague, must survive in blood in order to cause disease and to be transmitted from host to host by fleas. Members of the Ail/Lom family of outer membrane proteins provide protection from complement-dependent killing for a number of pathogenic bacteria. The Y. pestis KIM genome is predicted to encode four Ail/Lom family proteins. Y. pestis mutants specifically deficient in expression of each of these proteins were constructed using lambda Red-mediated recombination. The Ail outer membrane protein was essential for Y. pestis to resist complement-mediated killing at 26 and 37 degrees C. Ail was expressed at high levels at both 26 and 37 degrees C, but not at 6 degrees C. Expression of Ail in Escherichia coli provided protection from the bactericidal activity of complement. High-level expression of the three other Y. pestis Ail/Lom family proteins (the y1682, y2034, and y2446 proteins) provided no protection against complement-mediated bacterial killing. A Y. pestis ail deletion mutant was rapidly killed by sera obtained from all mammals tested except mouse serum. The role of Ail in infection of mice, Caenorhabditis elegans, and fleas was investigated.

  5. Doppel and PrPC co-immunoprecipitate in detergent-resistant membrane domains of epithelial FRT cells

    Science.gov (United States)

    Caputo, Anna; Sarnataro, Daniela; Campana, Vincenza; Costanzo, Maddalena; Negro, Alessandro; Sorgato, M. Catia; Zurzolo, Chiara

    2009-01-01

    Dpl (doppel) is a paralogue of the PrPC (cellular prion protein), whose misfolded conformer (the scrapie prion protein, PrPSc) is responsible for the onset of TSEs (transmissible spongiform encephalopathies) or prion diseases. It has been shown that the ectopic expression of Dpl in the brains of some lines of PrP-knockout mice provokes cerebellar ataxia, which can be rescued by the reintroduction of the PrP gene, suggesting a functional interaction between the two proteins. It is, however, still unclear where, and under which conditions, this event may occur. In the present study we addressed this issue by analysing the intracellular localization and the interaction between Dpl and PrPC in FRT (Fischer rat thyroid) cells stably expressing the two proteins separately or together. We show that both proteins localize prevalently on the basolateral surface of FRT cells, in both singly and doubly transfected clones. Interestingly we found that they associate with DRMs (detergent-resistant membranes) or lipid rafts, from where they can be co-immunoprecipitated in a cholesterol-dependent fashion. Although the interaction between Dpl and PrPC has been suggested before, our results provide the first clear evidence that this interaction occurs in rafts and is dependent on the integrity of these membrane microdomains. Furthermore, both Dpl and PrPC could be immunoprecipitated with flotillin-2, a raft protein involved in endocytosis and cell signalling events, suggesting that they share the same lipid environment. PMID:19888917

  6. Distribution of Glut1 in detergent-resistant membranes (DRMs) and non-DRM domains: effect of treatment with azide.

    Science.gov (United States)

    Rubin, Darrell; Ismail-Beigi, Faramarz

    2003-08-01

    We have previously shown that the acute stimulation of glucose transport in Clone 9 cells in response to azide is mediated by activation of Glut1 and that stomatin, a Glut1-binding protein, appears to inhibit Glut1 function. In Clone 9 cells under basal conditions, approximately 38% of Glut1, approximately 70% of stomatin, and the bulk of caveolin-1 was localized in the detergent-resistant membrane (DRM) fraction; a significant fraction of Glut1 is also present in DRMs of 3T3-L1 fibroblasts and human red blood cells (RBCs). Acute exposure to azide resulted in 40 and 50% decreases in the content of Glut1 in DRMs of Clone 9 cells and 3T3-L1 fibroblasts, respectively, whereas the distribution of stomatin and caveolin-1 in Clone 9 cells remained unchanged. In addition, treatment of Clone 9 cells with azide resulted in a approximately 50% decrease in the content of Glut1 in the DRM fraction of plasma membranes. We conclude that 1) a significant fraction of Glut1 is localized in DRMs, and 2) treatment of cells with azide results in a partial redistribution of Glut1 out of the DRM fraction.

  7. Detergent-resistant plasma membrane proteome in oat and rye: similarities and dissimilarities between two monocotyledonous plants.

    Science.gov (United States)

    Takahashi, Daisuke; Kawamura, Yukio; Yamashita, Tetsuro; Uemura, Matsuo

    2012-03-02

    The plasma membrane (PM) is involved in important cellular processes that determine the growth, development, differentiation, and environmental signal responses of plant cells. Some of these dynamic reactions occur in specific domains in the PM. In this study, we performed comparable nano-LC-MS/MS-based large-scale proteomic analysis of detergent-resistant membrane (DRM) fractions prepared from the PM of oat and rye. A number of proteins showed differential accumulation between the PM and DRM, and some proteins were only found in the DRM. Numerous proteins were identified as DRM proteins in oat (219 proteins) and rye (213 proteins), of which about half were identified only in the DRM. The DRM proteins were largely common to those found in dicotyledonous plants (Arabidopsis and tobacco), which suggests common functions associated with the DRM in plants. Combination of semiquantitative proteomic analysis and prediction of post-translational protein modification sites revealed differences in several proteins associated with the DRM in oat and rye. It is concluded that protein distribution in the DRM is unique from that in the PM, partly because of the physicochemical properties of the proteins, and the unique distribution of these proteins may define the functions of the specific domains in the PM in various physiological processes in plant cells.

  8. Small changes in environmental parameters lead to alterations in antibiotic resistance, cell morphology and membrane fatty acid composition in Staphylococcus lugdunensis.

    Directory of Open Access Journals (Sweden)

    Marcus J Crompton

    Full Text Available Staphylococcus lugdunensis has emerged as a major cause of community-acquired and nosocomial infections. This bacterium can rapidly adapt to changing environmental conditions to survive and capitalize on opportunities to colonize and infect through wound surfaces. It was proposed that S. lugdunensis would have underlying alterations in metabolic homeostasis to provide the necessary levels of adaptive protection. The aims of this project were to examine the impacts of subtle variations in environmental conditions on growth characteristics, cell size and membrane fatty acid composition in S. lugdunensis. Liquid broth cultures of S. lugdunensis were grown under varying combinations of pH (6-8, temperature (35-39°C and osmotic pressure (0-5% sodium chloride w/w to reflect potential ranges of conditions encountered during transition from skin surfaces to invasion of wound sites. The cells were harvested at the mid-exponential phase of growth and assessed for antibiotic minimal inhibitory concentration (MIC, generation time, formation of small colony variants, cell size (by scanning electron microscopy and membrane fatty acid composition. Stress regimes with elevated NaCl concentrations resulted in significantly higher antibiotic resistance (MIC and three of the combinations with 5% NaCl had increased generation times (P<0.05. It was found that all ten experimental growth regimes, including the control and centroid cultures, yielded significantly different profiles of plasma membrane fatty acid composition (P<0.0001. Alterations in cell size (P<0.01 were also observed under the range of conditions with the most substantial reduction occurring when cells were grown at 39°C, pH 8 (514±52 nm, mean ± Standard Deviation compared with cells grown under control conditions at 37°C with pH 7 (702±76 nm, P<0.01. It was concluded that S. lugdunensis responded to slight changes in environmental conditions by altering plasma membrane fatty acid composition

  9. The yeast ABC transporter Pdr18 (ORF YNR070w) controls plasma membrane sterol composition, playing a role in multidrug resistance

    Science.gov (United States)

    Cabrito, Tânia R.; Teixeira, Miguel C.; Singh, Ashutosh; Prasad, Rajendra; Sá-Correia, Isabel

    2011-01-01

    The action of multidrug efflux pumps in MDR (multidrug resistance) acquisition has been proposed to partially depend on the transport of physiological substrates which may indirectly affect drug partition and transport across cell membranes. In the present study, the PDR18 gene [ORF (open reading frame) YNR070w], encoding a putative PDR (pleiotropic drug resistance) transporter of the ATP-binding cassette superfamily, was found to mediate plasma membrane sterol incorporation in yeast. The physiological role of Pdr18 is demonstrated to affect plasma membrane potential and is proposed to underlie its action as a MDR determinant, conferring resistance to the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). The action of Pdr18 in yeast tolerance to 2,4-D, which was found to contribute to reduce [14C]2,4-D intracellular accumulation, may be indirect, given the observation that 2,4-D exposure deeply affects the sterol plasma membrane composition, this effect being much stronger in a Δpdr18 background. PDR18 activation under 2,4-D stress is regulated by the transcription factors Nrg1, controlling carbon source availability and the stress response, and, less significantly, Yap1, involved in oxidative stress and MDR, and Pdr3, a key regulator of the yeast PDR network, consistent with a broad role in stress defence. Taken together, the results of the present study suggest that Pdr18 plays a role in plasma membrane sterol incorporation, this physiological trait contributing to an MDR phenotype. PMID:21831043

  10. Effect of wastewater colloids on membrane removal of microconstituent antibiotic resistance genes

    OpenAIRE

    Riquelme Breazeal, Maria Virginia

    2011-01-01

    Anthropogenically generated antibiotic resistance genes (ARGs) are considered emerging contaminants, as they are associated with a critical human health challenge, are persist independent of a bacterial host, are subject to transfer between bacteria, and are present at amplified levels in human-impacted environments. Given the gravity of the problem, there is growing interest in advancing water treatment processes capable of limiting ARG dissemination. This study examined the potential for m...

  11. Detergent resistant membrane-associated IDE in brain tissue and cultured cells: Relevance to Aβ and insulin degradation

    Directory of Open Access Journals (Sweden)

    Castaño Eduardo M

    2008-12-01

    Full Text Available Abstract Background Insulin degrading enzyme (IDE is implicated in the regulation of amyloid β (Aβ steady-state levels in the brain, and its deficient expression and/or activity may be a risk factor in sporadic Alzheimer's disease (AD. Although IDE sub-cellular localization has been well studied, the compartments relevant to Aβ degradation remain to be determined. Results Our results of live immunofluorescence, immuno gold electron-microscopy and gradient fractionation concurred to the demonstration that endogenous IDE from brain tissues and cell cultures is, in addition to its other localizations, a detergent-resistant membrane (DRM-associated metallopeptidase. Our pulse chase experiments were in accordance with the existence of two pools of IDE: the cytosolic one with a longer half-life and the membrane-IDE with a faster turn-over. DRMs-associated IDE co-localized with Aβ and its distribution (DRMs vs. non-DRMs and activity was sensitive to manipulation of lipid composition in vitro and in vivo. When IDE was mis-located from DRMs by treating cells with methyl-β-cyclodextrin (MβCD, endogenous Aβ accumulated in the extracellular space and exogenous Aβ proteolysis was impaired. We detected a reduced amount of IDE in DRMs of membranes isolated from mice brain with endogenous reduced levels of cholesterol (Chol due to targeted deletion of one seladin-1 allele. We confirmed that a moderate shift of IDE from DRMs induced a substantial decrement on IDE-mediated insulin and Aβ degradation in vitro. Conclusion Our results support the notion that optimal substrate degradation by IDE may require its association with organized-DRMs. Alternatively, DRMs but not other plasma membrane regions, may act as platforms where Aβ accumulates, due to its hydrophobic properties, reaching local concentration close to its Km for IDE facilitating its clearance. Structural integrity of DRMs may also be required to tightly retain insulin receptor and IDE for

  12. Antibiotic Trapping by Plasmid-Encoded CMY-2 beta-Lactamase Combined with Reduced Outer Membrane Permeability as a Mechanism of Carbapenem Resistance in Escherichia coli

    NARCIS (Netherlands)

    Goessens, W.H.F.; van der Bij, A.K.; van Boxtel, R.; Pitout, J.D.D.; van Ulsen, J.P.; Melles, D.C.; Tommassen, J.

    2013-01-01

    A liver transplant patient was admitted with cholangitis, for which meropenem therapy was started. Initial cultures showed a carbapenem-susceptible (CS) Escherichia coli strain, but during admission, a carbapenem-resistant (CR) E. coli strain was isolated. Analysis of the outer membrane protein

  13. Antibiotic trapping by plasmid-encoded cmy-2-lactamase combined with reduced outer membrane permeability as a mechanism of carbapenem resistance in escherichia coli

    NARCIS (Netherlands)

    W.H.F. Goessens (Wil); A.K. van der Bij (Akke); R. van Boxtel (Ria); J.D.D. Pitout (J. D D); P. van Ulsen (Peter); D.C. Melles (Damian); J. Tommassen (Jan)

    2013-01-01

    textabstractA liver transplant patient was admitted with cholangitis, for which meropenem therapy was started. Initial cultures showed a carbapenem-susceptible (CS) Escherichia coli strain, but during admission, a carbapenem-resistant (CR) E. coli strain was isolated. Analysis of the outer membrane

  14. Prion Fragment Peptides Are Digested with Membrane Type Matrix Metalloproteinases and Acquire Enzyme Resistance through Cu2+-Binding

    Directory of Open Access Journals (Sweden)

    Aya Kojima

    2014-05-01

    Full Text Available Prions are the cause of neurodegenerative disease in humans and other mammals. The structural conversion of the prion protein (PrP from a normal cellular protein (PrPC to a protease-resistant isoform (PrPSc is thought to relate to Cu2+ binding to histidine residues. In this study, we focused on the membrane-type matrix metalloproteinases (MT-MMPs such as MT1-MMP and MT3-MMP, which are expressed in the brain as PrPC-degrading proteases. We synthesized 21 prion fragment peptides. Each purified peptide was individually incubated with recombinant MT1-MMP or MT3-MMP in the presence or absence of Cu2+ and the cleavage sites determined by LC-ESI-MS analysis. Recombinant MMP-7 and human serum (HS were also tested as control. hPrP61-90, from the octapeptide-repeat region, was cleaved by HS but not by the MMPs tested here. On the other hand, hPrP92-168 from the central region was cleaved by MT1-MMP and MT3-MMP at various sites. These cleavages were inhibited by treatment with Cu2+. The C-terminal peptides had higher resistance than the central region. The data obtained from this study suggest that MT-MMPs expressed in the brain might possess PrPC-degrading activity.

  15. NMR studies of the relationship between the changes of membrane lipids and the cisplatin-resistance of A549/DDP cells

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    Huang Youguo

    2003-04-01

    Full Text Available Abstract Changes of membrane lipids in cisplatin-sensitive A549 and cisplatin-resistant A549/DDP cells during the apoptotic process induced by a clinical dose of cisplatin (30 μM were detected by 1H and 31P-NMR spectroscopy and by membrane fluidity measurement. The apoptotic phenotypes of the two cell lines were monitored with flow cytometry. The assays of apoptosis showed that significant apoptotic characteristics of the A549 cells were induced when the cells were cultured for 24 hours after treatment with cisplatin, while no apoptotic characteristic could be detected for the resistant A549/DDP cells even after 48 hours. The results of 1H-NMR spectroscopy demonstrated that the CH2/CH3 and Glu/Ct ratios of the membrane of A549 cells increased significantly, but those in A549/DDP cell membranes decreased. In addition, the Chol/CH3 and Eth/Ct ratios decreased for the former but increased for the latter cells under the same conditions. 31P-NMR spectroscopy indicated levels of phosphomonoesters (PME and ATP decreased in A549 but increased in A549/DDP cells after being treated with cisplatin. These results were supported with the data obtained from 1H-NMR measurements. The results clearly indicated that components and properties of membrane phospholipids of the two cell lines were significantly different during the apoptotic process when they were treated with a clinical dose of cisplatin. Plasma membrane fluidity changes during cisplatin treatment as detected with the fluorescence probe TMA-DPH also indicate marked difference between the two cell lines. We provided evidence that there are significant differences in plasma membrane changes during treatment of cisplatin sensitive A549 and resistant A549/DDP cells.

  16. The effectiveness of styrene-maleic acid (SMA) copolymers for solubilisation of integral membrane proteins from SMA-accessible and SMA-resistant membranes.

    Science.gov (United States)

    Swainsbury, David J K; Scheidelaar, Stefan; Foster, Nicholas; van Grondelle, Rienk; Killian, J Antoinette; Jones, Michael R

    2017-10-01

    Solubilisation of biological lipid bilayer membranes for analysis of their protein complement has traditionally been carried out using detergents, but there is increasing interest in the use of amphiphilic copolymers such as styrene maleic acid (SMA) for the solubilisation, purification and characterisation of integral membrane proteins in the form of protein/lipid nanodiscs. Here we survey the effectiveness of various commercially-available formulations of the SMA copolymer in solubilising Rhodobacter sphaeroides reaction centres (RCs) from photosynthetic membranes. We find that formulations of SMA with a 2:1 or 3:1 ratio of styrene to maleic acid are almost as effective as detergent in solubilising RCs, with the best solubilisation by short chain variants (membranes was uniformly low, but could be increased through a variety of treatments to increase the lipid:protein ratio. However, proteins isolated from such membranes comprised clusters of complexes in small membrane patches rather than individual proteins. We conclude that short-chain 2:1 and 3:1 formulations of SMA are the most effective in solubilising integral membrane proteins, but that solubilisation efficiencies are strongly influenced by the size of the target protein and the density of packing of proteins in the membrane. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  17. The effect of real-time external resistance optimization on microbial fuel cell performance.

    Science.gov (United States)

    Pinto, R P; Srinivasan, B; Guiot, S R; Tartakovsky, B

    2011-02-01

    This work evaluates the impact of the external resistance (electrical load) on the long-term performance of a microbial fuel cell (MFC) and demonstrates the real-time optimization of the external resistance. For this purpose, acetate-fed MFCs were operated at external resistances, which were above, below, or equal to the internal resistance of a corresponding MFC. A perturbation/observation algorithm was used for the real-time optimal selection of the external resistance. MFC operation at the optimal external resistance resulted in increased power output, improved Coulombic efficiency, and low methane production. Furthermore, the efficiency of the perturbation/observation algorithm for maximizing long-term MFC performance was confirmed by operating an MFC fed with synthetic wastewater for over 40 days. In this test an average Coulombic efficiency of 29% was achieved. © 2010. Published by Elsevier Ltd. All rights reserved.

  18. 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.

  19. Green synthesized silver nanoparticles destroy multidrug resistant bacteria via reactive oxygen species mediated membrane damage

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    Balaram Das

    2017-09-01

    Full Text Available The growing need of antimicrobial agent for novel therapies against multi-drug resistant bacteria has drawn researchers to green nanotechnology. Especially, eco-friendly biosynthesis of silver nanoparticles (Ag NPs has shown its interesting impact against bacterial infection in laboratory research. In this study, a simple method was developed to form Ag NPs at room temperature, bio-reduction of silver ions from silver nitrate salt by leaf extract from Ocimum gratissimum. The Ag NPs appear to be capped with plant proteins, but are otherwise highly crystalline and pure. The Ag NPs have a zeta potential of −15 mV, a hydrodynamic diameter of 31 nm with polydispersity index of 0.65, and dry sizes of 18 ± 3 nm and 16 ± 2 nm, based on scanning and transmission electron microscopy respectively. The minimum inhibitory concentration (MIC of the Ag NPs against a multi-drug resistant Escherichia coli was 4 μg/mL and the minimum bactericidal concentration (MBC was 8 μg/mL, while the MIC and MBC against a resistant strain of Staphylococcus aureus were slightly higher at 8 μg/mL and 16 μg/mL respectively. Further, the Ag NPs inhibited biofilm formation by both Escherichia coli and S. aureus at concentrations similar to the MIC for each strain. Treatment of E. coli and S. aureus with Ag NPs resulted in damage to the surface of the cells and the production of reactive oxygen species. Both mechanisms likely contribute to bacterial cell death. In summary, this new method appears promising for green biosynthesis of pure Ag NPs with potent antimicrobial activity.

  20. Empirical mode decomposition and k-nearest embedding vectors for timely analyses of antibiotic resistance trends.

    Directory of Open Access Journals (Sweden)

    Douglas Teodoro

    Full Text Available BACKGROUND: Antibiotic resistance is a major worldwide public health concern. In clinical settings, timely antibiotic resistance information is key for care providers as it allows appropriate targeted treatment or improved empirical treatment when the specific results of the patient are not yet available. OBJECTIVE: To improve antibiotic resistance trend analysis algorithms by building a novel, fully data-driven forecasting method from the combination of trend extraction and machine learning models for enhanced biosurveillance systems. METHODS: We investigate a robust model for extraction and forecasting of antibiotic resistance trends using a decade of microbiology data. Our method consists of breaking down the resistance time series into independent oscillatory components via the empirical mode decomposition technique. The resulting waveforms describing intrinsic resistance trends serve as the input for the forecasting algorithm. The algorithm applies the delay coordinate embedding theorem together with the k-nearest neighbor framework to project mappings from past events into the future dimension and estimate the resistance levels. RESULTS: The algorithms that decompose the resistance time series and filter out high frequency components showed statistically significant performance improvements in comparison with a benchmark random walk model. We present further qualitative use-cases of antibiotic resistance trend extraction, where empirical mode decomposition was applied to highlight the specificities of the resistance trends. CONCLUSION: The decomposition of the raw signal was found not only to yield valuable insight into the resistance evolution, but also to produce novel models of resistance forecasters with boosted prediction performance, which could be utilized as a complementary method in the analysis of antibiotic resistance trends.

  1. High voltage time domain response of cMUT membrane: Laser interferometry measurements

    Science.gov (United States)

    Sénégond, Nicolas; Teston, Franck; Royer, Daniel; Meynier, Cyril; Certon, Dominique

    2010-01-01

    This paper deals with the understanding of cMUT membrane behavior during a high-voltage excitation. Measurements were performed with a homemade interferometer system. Experimental results in air and fluid (here oil) are discussed.

  2. Influence of solids retention time on continuous H{sub 2} production using membrane bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong-Yeol [Research Center for Material Cycles and Waste Management, National Institute for Environmental Studies,16-2 Onogawa, Tsukuba, Ibaraki 305 8506 (Japan); Li, Yu-You [Department of Environmental Science, Tohoku University, 6-6-06 Aoba, Sendai, Miyagi 980 8579 (Japan); Noike, Tatsuya [Advanced Research Institute for the Sciences and Humanities, Nihon University 12-5, Goban-cho, Chiyoda-ku, Tokyo 102 8251 (Japan)

    2010-01-15

    The influence of solids retention time (SRT) on continuous H{sub 2} production in a submerged membrane bioreactor (MBR) was investigated using mixed mesophilic microflora. The bioreactor was continuously operated at the four SRTs of 2, 4, 12.5 and 90 d on a glucose medium under the hydraulic retention time (HRT) of 9 h and the mesophilic condition of 35 C {+-} 0.5. Stable biogas production with H{sub 2} content of 50.8%-60% was achieved at SRTs ranging from 2 to 12.5 d. No methane gas was observed in monitoring the experimental conditions. The H{sub 2} production increased from 17.62 to 26.1 l-H{sub 2}/d when the SRT increased from 2 to 12.5 d, but decreased to 9.1 l-H{sub 2}/d at the 90 d SRT. The best H{sub 2} yield, 1.19 mol-H{sub 2}/mol-glucose, was observed at the SRT of 2 d and the highest H{sub 2} production rate, 5.8 l-H{sub 2}/l/d, was obtained at the SRT of 12.5 d. Stable H{sub 2} production was achieved by maintaining the SRT in the range of 2 - 12.5 d, regardless of the fermentative pathway related to higher lactate production. The decrease in H{sub 2} yield was observed at long SRTs due to the low volatile suspended solids/total suspended solids (VSS/TSS) as well as the high extracellular polymeric substances (EPS) concentrations. These results suggest that the SRT is the key factor enabling sustainable H{sub 2} fermentation in MBR, and that an SLR value of around 1.6 kg-DOC/kg-VSS/d might be the specific condition for achieving optimum H{sub 2} production. (author)

  3. Investigation of Antibacterial and Fouling Resistance of Silver and Multi-Walled Carbon Nanotubes Doped Poly(Vinylidene Fluoride-co-Hexafluoropropylene) Composite Membrane.

    Science.gov (United States)

    Macevele, Lutendo E; Moganedi, Kgabo L M; Magadzu, Takalani

    2017-07-13

    Composite membranes were successfully prepared using a phase-inversion method. The X-ray powder diffraction (XRD) and energy dispersive X-ray (EDX) profiles has confirmed formation of 4.8 wt % Ag/poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP), 3 wt % Ag-MWCNTs/PVDF-HFP (EDX surface composition of Ag nanoparticles) and 1.5 wt % MWCNTs/PVDF-HFP composite membranes. The MWCNTs crystallites are mainly encapsulated by a layer of PVDF-HFP, as evidenced by disappearance of graphitic peak. The scanning electron microscopy (SEM) images have depicted the formation of microporous structure, with few MWCNTs on the surface and strongly interacting with PVDF-HFP as demonstrated by thermogravimetric analysis (TGA), XRD and Fourier transform infrared (FTIR) data. The data indicated an increase in porosity, swellability and water content of the PVDF-HFP membrane with the addition of MWCNTs and/or Ag nanoparticles, showing an improved hydrophilicity. The 1.5 wt % MWCNTs/PVDF-HFP composite membrane showed good desalination and fouling resistance rates, which correlates with a low water contact angle. The combined effects of Ag nanoparticles and MWCNTs do not promote fouling resistance of PVDF-HFP membranes, as shown during NaCl microfiltration (this is linked with high water contact angle as compared to that of MWCNTs/PVDF-HFP composite). Both 1.5 wt % MWCNTs/PVDF-HFP and 3 wt % Ag-MWCNTs/PVDF-HFP composite membranes prevented the bacteria passing through the membrane (100% bacterial load reduction). The surface of 3 wt % Ag-MWCNTs/PVDF-HFP showed good bactericidal and non-leaching properties of the dopant materials (MWCNTs and Ag), as evidenced by bacterial growth on the edges of the membranes.

  4. Effects of hydrophilic solvent and oxidation resistance post surface treatment on molecular structure and forward osmosis performance of polyamide thin-film composite (TFC) membranes

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Qibo; Xu, Yangyu [School of Environment, Tsinghua University, Beijing 100084 (China); Shen, Jianquan [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Haijun, E-mail: yanghj@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhou, Lu, E-mail: zhoulu@tsinghua.edu.cn [School of Environment, Tsinghua University, Beijing 100084 (China)

    2015-11-30

    Graphical abstract: - Highlights: • NMP promotes swelling of polyamide, which enhances the TFC FO membrane water flux. • Electron-withdrawing carboxyl groups reduce the activity of polyamide molecules. • TMC and oxalic acid can improve the oxidation resistance properties of the FO membrane. • Oxalic acid and EDC improve the FO membrane separation performance significantly. - Abstract: In this article, novel hydrophilic solvents and antioxidants were used to post-treat aromatic polyamide thin-film composite (TFC) hollow fiber forward osmosis (FO) membranes. The effects of trimesoyl chloride (TMC) and oxalic acid on the structure of polyamide skin layer were investigated using ATR-FTIR and XPS analyses. Pure water flux and rejection of salts were detected using 2 M NaCl solution as draw solutions in FO processes. The results demonstrated that hydrophilic solvent N-methyl pyrrolidone (NMP) enhanced the water flux and kept a high salt retention of the TFC FO membrane. TMC and oxalic acid were both found to improve the oxidation resistance properties of the skin layer of TFC membrane because the electron-withdrawing carboxyl groups reduced the activity of polyamide molecular. The effects of the oxalic acid and carbodiimide on the molecular structures and the FO water flux of the polyamide TFC membranes were more marked than those of TMC. The novel TFC FO membrane treated by oxalic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) exhibited a high level of water flux (20.33 L m{sup −2} h{sup −1}), and the rates of salt rejection and salt reverse rejection were higher by 50% and 83%, respectively.

  5. Single Molecule 3D Orientation in Time and Space: A 6D Dynamic Study on Fluorescently Labeled Lipid Membranes

    DEFF Research Database (Denmark)

    Börner, Richard; Ehrlich, Nicky; Hohlbein, Johannes

    2016-01-01

    . As the method is based on the detection of single photons, it additionally allows for performing fluorescence correlation spectroscopy (FCS) as well as dynamical anisotropy measurements thereby providing access to fast orientational dynamics down to the nanosecond time scale. The 3D orientation is particularly...... interesting in non-isotropic environments such as lipid membranes, which are of great importance in biology. We used giant unilamellar vesicles (GUVs) labeled with fluorescent dyes down to a single molecule concentration as a model system for both, assessing the robustness of the orientation determination...... simulations of the rotational dynamics of dipoles incorporated into lipid membranes. Our study offers a comprehensive view on the dye orientation behavior in a lipid membrane with high spatiotemporal resolution representing a six-dimensional fluorescence detection approach....

  6. Outer membrane protein STM3031 (Ail/OmpX-like protein) plays a key role in the ceftriaxone resistance of Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    Hu, Wensi S; Lin, Jing-Fang; Lin, Ying-Hsiu; Chang, Hsin-Yu

    2009-08-01

    Previously, the putative outer membrane protein STM3031 has been correlated with ceftriaxone resistance in Salmonella enterica serovar Typhimurium. In this study, this protein was almost undetectable in the ceftriaxone-susceptible strain 01-4, but its levels were increased in 01-4 isogenic strains for which MICs were higher. The stm3031 gene deletion mutant, R200(Deltastm3031), was generated and showed >64-fold lower ceftriaxone resistance than R200, supporting a key role for STM3031 in ceftriaxone resistance. To investigate which outer membrane protein(s) was associated with resistance, the outer membrane protein profiles of 01-4, R200, and R200(Deltastm3031) were compared proteomically. Nine proteins were identified as altered. The expression levels of AcrA, TolC, STM3031, STM1530, VacJ, and Psd in R200 were increased; those of OmpC, OmpD, and OmpW were decreased. The expression levels of OmpD, OmpW, STM1530, VacJ, and Psd, but not those of OmpC, AcrA, and TolC, in R200(Deltastm3031) were returned to the levels in strain 01-4. Furthermore, the genes' mRNA levels correlated with their protein levels when the three strains were compared. The detection of higher AcrB levels, linked to higher acrB, acrD, and acrF mRNA levels, in strain R200 than in strains 01-4 and R200(Deltastm3031) suggests that AcrB, AcrD, and AcrF participate in ceftriaxone resistance. Taken together with the location of STM3031 in the outer membrane, these results suggest that STM3031 plays a key role in ceftriaxone resistance, probably by reducing permeability via a decreased porin OmpD level and enhancing export via increased AcrD efflux pump activity.

  7. The memory during prison time: in between massification and resistance

    Directory of Open Access Journals (Sweden)

    José Mauro Oliveira Braz

    2016-04-01

    Full Text Available This article aims to understand how the penitentiary institution can, through its dynamics, experiences and disciplinary practices, enable the balance of subjective differences from jailed people by the assimilation of living standards in terms of submission and obedience to the culture prison. As for the methodology used, the literature that aided the construction of this discussion and directed this work came from authors such as Foucault, Goffman, Thompson and Althusser directed such work. The phenomenon of “subjective massification” is present to the extent where institutions act in order to produce similar experiences in prison, turning them into traces of memories and souvenirs. Thus, the prison, like any other place of memory, conducts its incarcerated subjects according to a set of determinations established for the transmission of discipline and control. But the prison environment that acts in the pursuit of subjective standardization is based on contradictions and forces of correlations that also give way to resistance. Configuring, in that way, not only the preservation of the memory from that selected space, but also the production arrangements, or even better, a memory modality in terms of possible circumstances that require the power of the institution.

  8. Terminal Galactosylation and Sialylation Switching on Membrane Glycoproteins upon TNF-Alpha-Induced Insulin Resistance in Adipocytes.

    Science.gov (United States)

    Parker, Benjamin L; Thaysen-Andersen, Morten; Fazakerley, Daniel J; Holliday, Mira; Packer, Nicolle H; James, David E

    2016-01-01

    Insulin resistance (IR) is a complex pathophysiological state that arises from both environmental and genetic perturbations and leads to a variety of diseases, including type-2 diabetes (T2D). Obesity is associated with enhanced adipose tissue inflammation, which may play a role in disease progression. Inflammation modulates protein glycosylation in a variety of cell types, and this has been associated with biological dysregulation. Here, we have examined the effects of an inflammatory insult on protein glycosylation in adipocytes. We performed quantitative N-glycome profiling of membrane proteins derived from mouse 3T3-L1 adipocytes that had been incubated with or without the proinflammatory cytokine TNF-alpha to induce IR. We identified the regulation of specific terminal N-glycan epitopes, including an increase in terminal di-galactose- and a decrease in biantennary alpha-2,3-sialoglycans. The altered N-glycosylation of TNF-alpha-treated adipocytes correlated with the regulation of specific glycosyltransferases, including the up-regulation of B4GalT5 and Ggta1 galactosyltransferases and down-regulation of ST3Gal6 sialyltransferase. Knockdown of B4GalT5 down-regulated the terminal di-galactose N-glycans, confirming the involvement of this enzyme in the TNF-alpha-regulated N-glycome. SILAC-based quantitative glycoproteomics of enriched N-glycopeptides with and without deglycosylation were used to identify the protein and glycosylation sites modified with these regulated N-glycans. The combined proteome and glycoproteome workflow provided a relative quantification of changes in protein abundance versus N-glycosylation occupancy versus site-specific N-glycans on a proteome-wide level. This revealed the modulation of N-glycosylation on specific proteins in IR, including those previously associated with insulin-stimulated GLUT4 trafficking to the plasma membrane. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Terminal Galactosylation and Sialylation Switching on Membrane Glycoproteins upon TNF-Alpha-Induced Insulin Resistance in Adipocytes*

    Science.gov (United States)

    Parker, Benjamin L.; Thaysen-Andersen, Morten; Fazakerley, Daniel J.; Holliday, Mira; Packer, Nicolle H.; James, David E.

    2016-01-01

    Insulin resistance (IR) is a complex pathophysiological state that arises from both environmental and genetic perturbations and leads to a variety of diseases, including type-2 diabetes (T2D). Obesity is associated with enhanced adipose tissue inflammation, which may play a role in disease progression. Inflammation modulates protein glycosylation in a variety of cell types, and this has been associated with biological dysregulation. Here, we have examined the effects of an inflammatory insult on protein glycosylation in adipocytes. We performed quantitative N-glycome profiling of membrane proteins derived from mouse 3T3-L1 adipocytes that had been incubated with or without the proinflammatory cytokine TNF-alpha to induce IR. We identified the regulation of specific terminal N-glycan epitopes, including an increase in terminal di-galactose- and a decrease in biantennary alpha-2,3-sialoglycans. The altered N-glycosylation of TNF-alpha-treated adipocytes correlated with the regulation of specific glycosyltransferases, including the up-regulation of B4GalT5 and Ggta1 galactosyltransferases and down-regulation of ST3Gal6 sialyltransferase. Knockdown of B4GalT5 down-regulated the terminal di-galactose N-glycans, confirming the involvement of this enzyme in the TNF-alpha-regulated N-glycome. SILAC-based quantitative glycoproteomics of enriched N-glycopeptides with and without deglycosylation were used to identify the protein and glycosylation sites modified with these regulated N-glycans. The combined proteome and glycoproteome workflow provided a relative quantification of changes in protein abundance versus N-glycosylation occupancy versus site-specific N-glycans on a proteome-wide level. This revealed the modulation of N-glycosylation on specific proteins in IR, including those previously associated with insulin-stimulated GLUT4 trafficking to the plasma membrane. PMID:26537798

  10. Resisting the power of organizations in Modern Times : May we all be Charlot?

    OpenAIRE

    Debenedetti, Stéphane; Huault, Isabelle; Perret, Véronique

    2015-01-01

    A large body of literature has emphasised the importance of every day forms of resistance in the workplace. In this paper, we seek to overcome the criticism of localism and banality that has been directed towards the everyday view of individualistic resistance as well as the limits of the conception of creative resistance that aims to co-produce change within a given system of power. To do this, we highlight and discuss the ideas concerning resistance generated by the film Modern Times, and m...

  11. Distinct constrictive processes, separated in time and space,divide Caulobacter inner and outer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Judd, Ellen M.; Comolli, Luis R.; Chen, Joseph C.; Downing,Kenneth H.; Moerner, W.E.; McAdams, Harley H.

    2005-05-01

    Cryo-electron microscope tomography (cryoEM) and a fluorescence loss in photobleaching (FLIP) assay were used to characterize progression of the terminal stages of Caulobacter crescentus cell division. Tomographic cryoEM images of the cell division site show separate constrictive processes closing first the inner, and then the outer, membrane in a manner distinctly different from septum-forming bacteria. The smallest observed pre-fission constrictions were 60 nm for both the inner and outer membrane. FLIP experiments had previously shown cytoplasmic compartmentalization, when cytoplasmic proteins can no longer diffuse between the two nascent progeny cell compartments, occurring 18 min before daughter cell separation in a 135 min cell cycle. Here, we used FLIP experiments with membrane-bound and periplasmic fluorescent proteins to show that (1) periplasmic compartmentalization occurs after cytoplasmic compartmentalization, consistent with the cryoEM observations, and (2) inner membrane and periplasmic proteins can diffuse past the FtsZ constriction site, indicating that the cell division machinery does not block membrane diffusion.

  12. Extracorporeal membrane oxygenation and toilet bronchoscopy as a bridge to pneumonectomy in severe community-acquired methicillin-resistant Staphylococcus aureus pneumonia

    Science.gov (United States)

    Panchabhai, Tanmay S.; Khabbaza, Joseph E.; Raja, Siva; Mehta, Atul C.; Hatipoğlu, Umur

    2015-01-01

    Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) pneumonia is associated with very high mortality. Though surgical evacuation of necrotic tissue is desirable in patients unresponsive to antimicrobial therapy, most patients are acutely ill precluding surgical intervention. We utilized a combination of extracorporeal membrane oxygenation (ECMO) with frequent toilet bronchoscopies to salvage an unaffected right lung from spillage of necrotic pus from left lung cavitary CA-MRSA pneumonia in a 22-year-old patient. Our patient while on ECMO and after decannulation was positioned with the right lung up at all times with 1-2 toilet bronchoscopies every day for almost 30 days. This time was utilized for ventilator weaning and optimizing the nutritional status prior to extrapleural left pneumonectomy. Prevention of soilage of the unaffected right lung and mitigating volutrauma with ECMO support combined with the subsequent surgical evacuation of necrotic left lung tissue led to a favorable outcome in this case. This strategy could be of value in similar presentations of unilateral suppurative pneumonia, where the progressive disease occurs despite optimal medical therapy. PMID:26664570

  13. Variations in skid resistance over time, part 1

    Science.gov (United States)

    Runkle, S. N.; Mahone, D. C.

    1980-02-01

    The Virginia Department of Highways and Transportation survey skid trailer, the Department's research trailer, the research stopping distance car, and the grease patch method of measuring surface texture were evaluated with respect to time and weather dependent changes in measured values. The grease patch method of measuring texture seems to have the same basic relationship to weather variables as does the Department's survey trailer, but the relationship is consistent among sites. Also, the use of this method is time consuming and expensive. The research trailer experienced so many breakdowns that the researchers place little confidence in the results obtained with this testing device. For the stopping distance car it was found that the average standard deviation for all test speeds on the six sites tested was 3.26 skid numbers.

  14. Time-dependent measurements over membrane plates at low Reynolds number

    Science.gov (United States)

    Hubner, James; Scott, Kyle; Timpe, Amory; Ukeiley, Lawrence

    2010-11-01

    A segment of low Reynolds number aerodynamic research employs biomimetics for optimization of airfoil shapes to micro air vehicle (MAV) flight. Many of these efforts focus on thin, flexible membrane airfoils inspired by small birds, bats and insects. This design approach, mimicking low Reynolds number flyers (Re hot-wire anemometry) and surface deflection (laser vibrometry) measurements over rigid plates and flexible membranes at incidence to the free stream flow. A range of flow Reynolds numbers are examined, from 10,000 to 50,000, in which vibration initiates and grow with increasing velocity.

  15. Does Increased Expression of the Plasma Membrane Calcium-ATPase Isoform 2 Confer Resistance to Apoptosis on Breast Cancer Cells?

    National Research Council Canada - National Science Library

    VanHouten, Joshua N

    2008-01-01

    The plasma membrane calcium ATPase isoform 2 (PMCA2) is highly expressed on the apical membrane of mammary epithelial cells during lactation, and is the predominant pump responsible for calcium transport into milk...

  16. N-linked glycans do not affect plasma membrane localization of multidrug resistance protein 4 (MRP4) but selectively alter its prostaglandin E2 transport activity.

    Science.gov (United States)

    Miah, M Fahad; Conseil, Gwenaëlle; Cole, Susan P C

    2016-01-22

    Multidrug resistance protein 4 (MRP4) is a member of subfamily C of the ATP-binding cassette superfamily of membrane transport proteins. MRP4 mediates the ATP-dependent efflux of many endogenous and exogenous solutes across the plasma membrane, and in polarized cells, it localizes to the apical or basolateral plasma membrane depending on the tissue type. MRP4 is a 170 kDa glycoprotein and here we show that MRP4 is simultaneously N-glycosylated at Asn746 and Asn754. Furthermore, confocal immunofluorescence studies showed that N-glycans do not affect MRP4's apical membrane localization in polarized LLC-PK1 cells or basolateral membrane localization in polarized MDCKI cells. However, vesicular transport assays showed that N-glycans differentially affect MRP4's ability to transport prostaglandin E2, but not estradiol glucuronide. Together these data indicate that N-glycosylation at Asn746 and Asn754 is not essential for plasma membrane localization of MRP4 but cause substrate-selective effects on its transport activity. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Time-dependent effect of rutin on skin fibroblasts membrane disruption following UV radiation

    Directory of Open Access Journals (Sweden)

    Agnieszka Gęgotek

    2017-08-01

    In conclusion, highest skin fibroblasts membrane level of rutin occurred in 2–4 h following UVA/B-radiation results in its strongest effect on biomembrane structure and functions and cellular antioxidant system irrespective of the radiation type.

  18. An improved method for the real time calculation of soil resistance during driving

    NARCIS (Netherlands)

    Foeken, R.J. van; Daniels, B.J.; Middendorp, P.

    1996-01-01

    The limited time between two successive blows during pile driving has resulted in the development of simple methods to calculate the soil resistance real time. These methods are called direct methods like the Case (Goble) method and Impedance method. Other more time consuming methods are called

  19. Effects of Aloe Vera and Chitosan Nanoparticle Thin-Film Membranes on Wound Healing in Full Thickness Infected Wounds with Methicillin Resistant Staphylococcus Aureus.

    Science.gov (United States)

    Ranjbar, Reza; Yousefi, Alireza

    2018-01-01

    To assess effect of Aleo vera with chitosan nanoparticle biofilm on wound healing in full thickness infected wounds with antibiotic resistant gram positive bacteria. Thirty rats were randomized into five groups of six rats each. Group I: Animals with uninfected wounds treated with 0.9% saline solution. Group II: Animals with infected wounds treated with saline. Group III: Animals with infected wounds were dressed with chitosan nanoparticle thin-film membranes. Group IV: Animals with infected wounds were treated topically with Aloe vera and Group V: Animals with infected wounds were treated topically with Aloe vera and dressed with chitosan nanoparticle thin-film membranes. Wound size was measured on 6, 9, 12, 15, 18 and 21days after surgery. Microbiology, reduction in wound area and hydroxyproline contents indicated that there was significant difference ( p vera with chitosan nanoparticle thin-film membranes had a reproducible wound healing potential and hereby justified its use in practice.

  20. Design and membrane-disruption mechanism of charge-enriched AMPs exhibiting cell selectivity, high-salt resistance, and anti-biofilm properties.

    Science.gov (United States)

    Han, Hyo Mi; Gopal, Ramamourthy; Park, Yoonkyung

    2016-02-01

    Cationic antimicrobial peptides (AMPs) are essential components of the innate immune system, offering protection against invading pathogenic bacteria. In nature, AMPs serve as antibiotics with broad-spectrum antimicrobial and anti-biofilm properties. However, low effective stability in high-salt environments and physiological instability in biological membranes limit the applicability of naturally occurring AMPs as novel therapeutics. We therefore designed short synthetic cationic peptides by substituting key residues in myxinidin, an AMP derived from the epidermal mucus of hagfish, with lysine (Lys, K), arginine (Arg, R), and tryptophan (Trp, W). The resultant myxinidin analogs exhibited strong antimicrobial activity against both Gram-positive and Gram-negative bacteria, including multidrug-resistant strains, even under high-salt conditions. Moreover, these peptides showed high binding affinity for both lipopolysaccharides and lipoteichoic acids and inhibited biofilm formation by most bacteria, but did not cause significant lysis of human red blood cells and were not cytotoxic to normal human keratinocytes. Circular dichroism analysis revealed that myxinidin and its analogs assumed α-helical or β-sheet structures within artificial liposomes and bacterial membranes. In addition, bacterial killing and membrane permeation experiments demonstrated that the myxinidin analogs permeated through bacterial membranes, leading to cytoplasmic disruption and cell death. Taken together, these findings suggest myxinidin analogs may be promising candidate antibiotic agents for therapeutic application against antibiotic-resistant bacteria.

  1. Programmed Fetal Membrane Senescence and Exosome-Mediated Signaling: A Mechanism Associated With Timing of Human Parturition

    Directory of Open Access Journals (Sweden)

    Ramkumar Menon

    2017-08-01

    Full Text Available Human parturition is an inflammatory process that involves both fetal and maternal compartments. The precise immune cell interactions have not been well delineated in human uterine tissues during parturition, but insights into human labor initiation have been informed by studies in animal models. Unfortunately, the timing of parturition relative to fetal maturation varies among viviparous species—indicative of different phylogenetic clocks and alarms—but what is clear is that important common pathways must converge to control the birth process. Herein, we hypothesize a novel signaling mechanism initiated by human fetal membrane aging and senescence-associated inflammation. Programmed events of fetal membrane aging coincide with fetal growth and organ maturation. Mechanistically, senescence involves in telomere shortening and activation of p38 mitogen-activated signaling kinase resulting in aging-associated phenotypic transition. Senescent tissues release inflammatory signals that are propagated via exosomes to cause functional changes in maternal uterine tissues. In vitro, oxidative stress causes increased release of inflammatory mediators (senescence-associated secretory phenotype and damage-associated molecular pattern markers that can be packaged inside the exosomes. These exosomes traverse through tissues layers, reach maternal tissues to increase overall inflammatory load transitioning them from a quiescent to active state. Animal model studies have shown that fetal exosomes can travel from fetal to the maternal side. Thus, aging fetal membranes and membrane-derived exosomes cargo fetal signals to the uterus and cervix and may trigger parturition. This review highlights a novel hypothesis in human parturition research based on data from ongoing research using human fetal membrane model system.

  2. Time-dependent effect of rutin on skin fibroblasts membrane disruption following UV radiation.

    Science.gov (United States)

    Gęgotek, Agnieszka; Bielawska, Katarzyna; Biernacki, Michał; Dobrzyńska, Izabela; Skrzydlewska, Elżbieta

    2017-08-01

    Chronic exposure of the skin to solar UV radiation induces a number of biological alterations, including a redox imbalance; therefore, there is an urgent need for skin cells protective compounds. The aim of this study was to determine the effects of natural, previously extensively examined, polyphenol with antioxidant properties - rutin, on UV-induced skin fibroblasts membrane disruption. Accordingly, fibroblasts exposed to UVA and UVB irradiation were incubated with rutin (12h before and/or up to 24h after irradiation), and the structural and metabolic changes were examined. Rutin penetration through the fibroblast phospholipid bilayer was aided by UVA-induced bilitranslocase activity 2-4h after irradiation, while UVB irradiation led to enhanced phospholipid peroxidation and higher membrane permeability to facilitate the interaction of rutin with phospholipids. Lipidomic analysis revealed that 4h of rutin treatment also partially prevented UVA/B-induced increase in phosphatidylethanolamine and phosphatidylcholine level, as well as their membrane localization, which resulted in an enhanced zeta potential in the cells and liposomes. Moreover, rutin 2h following irradiation, in a various degree, prevented the increased in phospholipase A2 activity and ROS generation, and partially protected against the reduction of arachidonic and linoleic acids level and the lipid peroxidation product 4-hydroxynonenal level increase. Rutin effectively prevented against decrease in glutathione peroxidase, glutathione and vitamins E and C activities/levels, particularly 2h following UVA irradiation. In conclusion, highest skin fibroblasts membrane level of rutin occurred in 2-4h following UVA/B-radiation results in its strongest effect on biomembrane structure and functions and cellular antioxidant system irrespective of the radiation type. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  3. Time efficient methods for scanning a fluorescent membrane with a fluorescent microscopic imager for the quality assurance of food

    Science.gov (United States)

    Lerm, Steffen; Holder, Silvio; Schellhorn, Mathias; Brückner, Peter; Linß, Gerhard

    2013-05-01

    An important part of the quality assurance of meat is the estimation of germs in the meat exudes. The kind and the number of the germs in the meat affect the medical risk for the consumer of the meat. State-of-the-art analyses of meat are incubator test procedures. The main disadvantages of such incubator tests are the time consumption, the necessary equipment and the need of special skilled employees. These facts cause in high inspection cost. For this reason a new method for the quality assurance is necessary which combines low detection limits and less time consumption. One approach for such a new method is fluorescence microscopic imaging. The germs in the meat exude are caught in special membranes by body-antibody reactions. The germ typical signature could be enhanced with fluorescent chemical markers instead of reproduction of the germs. Each fluorescent marker connects with a free germ or run off the membrane. An image processing system is used to detect the number of fluorescent particles. Each fluorescent spot should be a marker which is connected with a germ. Caused by the small object sizes of germs, the image processing system needs a high optical magnification of the camera. However, this leads to a small field of view and a small depth of focus. For this reasons the whole area of the membrane has to be scanned in three dimensions. To minimize the time consumption, the optimal path has to be found. This optimization problem is influenced by features of the hardware and is presented in this paper. The traversing range in each direction, the step width, the velocity, the shape of the inspection volume and the field of view have influence on the optimal path to scan the membrane.

  4. Computational design of heat resistant steels with evolving and time-independent strengthening factors

    NARCIS (Netherlands)

    Lu, Q.

    2015-01-01

    Alloy design by the traditional trial and error approach is known to be a time consuming and a highly cost procedure, especially for the design of heat resistant steel where the feedback time is intrinsically long. The significant developments in computational simulation techniques in the last

  5. Properties of a six-gap timing resistive plate chamber with strip readout

    International Nuclear Information System (INIS)

    Ammosov, V.V.; Gapienko, V.A.; Semak, A.A.; Sviridov, Yu.M.; Zaets, V.G.; Gavrishchuk, O.P.; Kuz'min, N.A.; Sychkov, S.Ya.; Usenko, E.A.; Yukaev, A.I.

    2009-01-01

    Six-gap glass timing resistive plate chamber with strip readout was tested using IHEP U-70 PS test beam. The time resolution of ∼ 45 ps at efficiency larger than 98% was achieved. Position resolution along strip was estimated to be ∼1 cm

  6. Time to sputum conversion in multidrug-resistant tuberculosis patients in Armenia: retrospective cohort study

    Directory of Open Access Journals (Sweden)

    Arax Hovhannesyan

    2012-06-01

    Full Text Available OBJECTIVE: To characterize time to sputum conversion among patients with multidrug resistant tuberculosis who were enrolled into second-line tuberculosis treatment program; to identify risk factors for delayed sputum conversion. DESIGN: Retrospective cohort study designed to identify the factors associated with sputum conversion. Survival analysis was performed using Kaplan-Meier estimator to compute estimates for median time to sputum conversion and Cox proportional hazards model to compute hazard ratios (HR. RESULTS: Sputum conversion from positive to negative was observed in 134 out of 195 cases (69%. Among these who converted the median time to conversion was 3.7 months. Factors independently associated with time to sputum conversion in the proportional hazards model were: male sex (HR=0.51, 95% CI 0.32-0.81, ofloxacin-resistant tuberculosis (HR = 0.45, 95% CI 0.26-0.78 and first period of recruitment into second-line treatment (HR= 0.69, 95% CI 0.47-1.01. CONCLUSION: Time to sputum conversion in patients with multidrug-resistant tuberculosis in Armenia was 5.8 months (range 0.5-17.0 months. High level of ofloxacin resistance was the main reason for compromised response to treatment. Patients with a poor resistance profile and males should be targeted with more aggressive initial therapy.

  7. Time to sputum conversion in multidrug-resistant tuberculosis patients in Armenia: retrospective cohort study

    Directory of Open Access Journals (Sweden)

    Arax Hovhannesyan

    2012-01-01

    Full Text Available OBJECTIVE: To characterize time to sputum conversion among patients with multidrug resistant tuberculosis who were enrolled into second-line tuberculosis treatment program; to identify risk factors for delayed sputum conversion. DESIGN: Retrospective cohort study designed to identify the factors associated with sputum conversion. Survival analysis was performed using Kaplan-Meier estimator to compute estimates for median time to sputum conversion and Cox proportional hazards model to compute hazard ratios (HR. RESULTS: Sputum conversion from positive to negative was observed in 134 out of 195 cases (69%. Among these who converted the median time to conversion was 3.7 months. Factors independently associated with time to sputum conversion in the proportional hazards model were: male sex (HR=0.51, 95% CI 0.32-0.81, ofloxacin-resistant tuberculosis (HR = 0.45, 95% CI 0.26-0.78 and first period of recruitment into second-line treatment (HR= 0.69, 95% CI 0.47-1.01. CONCLUSION: Time to sputum conversion in patients with multidrug-resistant tuberculosis in Armenia was 5.8 months (range 0.5- 17.0 months. High level of ofloxacin resistance was the main reason for compromised response to treatment. Patients with a poor resistance profile and males should be targeted with more aggressive initial therapy.

  8. Characteristics of DNA-AuNP networks on cell membranes and real-time movies for viral infection.

    Science.gov (United States)

    Li, Chunmei; Zheng, Linling; Yang, Xiaoxi; Wan, Xiaoyan; Wu, Wenbi; Zhen, Shujun; Li, Yuanfang; Luo, Lingfei; Huang, Chengzhi

    2016-03-01

    This data article provides complementary data for the article entitled "DNA-AuNP networks on cell membranes as a protective barrier to inhibit viral attachment, entry and budding" Li et al. (2016) [1]. The experimental methods for the preparation and characterization of DNA-conjugated nanoparticle networks on cell membranes were described. Confocal fluorescence images, agarose gel electrophoresis images and hydrodynamic diameter of DNA-conjugated gold nanoparticle (DNA-AuNP) networks were presented. In addition, we have prepared QDs-labeled RSV (QDs-RSV) to real-time monitor the RSV infection on HEp-2 cells in the absence and presence of DNA-AuNP networks. Finally, the cell viability of HEp-2 cells coated by six types of DNA-nanoparticle networks was determined after RSV infection.

  9. Quantitative and real-time effects of carbon quantum dots on single living HeLa cell membrane permeability.

    Science.gov (United States)

    Kong, Weiqian; Liu, Juan; Liu, Ruihua; Li, Hao; Liu, Yang; Huang, Hui; Li, Kunyang; Liu, Jian; Lee, Shuit-Tong; Kang, Zhenhui

    2014-05-21

    The interaction between carbon quantum dots (CQDs) and a single living cell was explored in real time. Here, we provide the quantitative data on the permeability of the HeLa cell membrane in the presence of CQDs with different surface functional groups (CQDs terminated with -OH/-COOH (CQD-OH), -PEG (CQD-PEG), and -NH2 (CQD-NH2)). Although these CQDs have very low toxicity towards HeLa cells, they still increase the cell membrane permeability by 8%, 13%, and 19% for CQD-PEG, CQD-OH, and CQD-NH2, respectively, and this kind of permeability was irreversible. These observations are valuable for promoting the bio-applications of carbon nanostructures in living systems.

  10. Comparison of different cells for resistance determination of freely standing polymer membranes developed for direct methanol fuel cell (DMFC) applications

    Czech Academy of Sciences Publication Activity Database

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

    2002-01-01

    Roč. 147, 1-3 (2002), s. 191-196 ISSN 0011-9164. [International Congress on Membranes and Membrane Processes. Toulouse, 07.07.2002-12.07.2002] R&D Projects: GA MŠk ME 366 Grant - others:GA-(DE) WTZ CZE 028/00 Institutional research plan: CEZ:AV0Z4050913 Keywords : conducting polymer membranes * impedance spectroscopy * sulfonated poly(phenylene oxide) Subject RIV: CG - Electrochemistry Impact factor: 0.517, year: 2002

  11. Degradation of Polypropylene Membranes Applied in Membrane Distillation Crystallizer

    Directory of Open Access Journals (Sweden)

    Marek Gryta

    2016-03-01

    Full Text Available The studies on the resistance to degradation of capillary polypropylene membranes assembled in a membrane crystallizer were performed. The supersaturation state of salt was achieved by evaporation of water from the NaCl saturated solutions using membrane distillation process. A high feed temperature (363 K was used in order to enhance the degradation effects and to shorten the test times. Salt crystallization was carried out by the application of batch or fluidized bed crystallizer. A significant membrane scaling was observed regardless of the method of realized crystallization. The SEM-EDS, DSC, and FTIR methods were used for investigations of polypropylene degradation. The salt crystallization onto the membrane surface accelerated polypropylene degradation. Due to a polymer degradation, the presence of carbonyl groups on the membranes’ surface was identified. Besides the changes in the chemical structure a significant mechanical damage of the membranes, mainly caused by the internal scaling, was also found. As a result, the membranes were severely damaged after 150 h of process operation. A high level of salt rejection was maintained despite damage to the external membrane surface.

  12. The impact of time of delivery on gestations complicated by preterm premature rupture of membranes: daytime versus nighttime.

    Science.gov (United States)

    Moussa, Hind; Hosseini Nasab, Susan; Fournie, David; Ontiveros, Alejandra; Alkawas, Rim; Chauhan, Suneet; Blackwell, Sean; Sibai, Baha

    2018-04-09

    Perinatal death, in particular intrapartum stillbirth and short-term neonatal death, as well as neonatal short term and long term morbidity have been associated with the time of day that the birth occurs. Indeed, evening and nighttime deliveries were associated with an increased risk of an adverse perinatal outcome when compared to similar daytime deliveries. Impact of shift change, as well as time of day delivery have been extensively studied in the context of maternal and neonatal complications of cesarean delivery, however, no studies were previously performed on timing of delivery and its effect on the outcome of pregnancies complicated by preterm premature rupture of membranes. Our objective was to compare obstetric, neonatal as well as long-term outcomes between women delivered in the daytime versus nighttime, in singleton gestations whose pregnancies were complicated by preterm premature rupture of membranes. This was a secondary analysis of a trial of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network "A Randomized Clinical Trial of the Beneficial Effects of Antenatal Magnesium Sulfate for the Prevention of Cerebral Palsy". For this analysis, the time of delivery was divided into the daytime, from 07:01 to 19:00, and the nighttime, from 19:01 to 07:00. Epidemiological, obstetric characteristics as well as neonatal and long-term outcomes were compared between deliveries occurring during the daytime versus the nighttime periods. Inclusion criteria consisted of singleton gestations diagnosed with preterm premature rupture of membranes (PPROM). Multifetal gestations and pregnancies with preterm labor without preterm premature rupture of membranes were excluded. A total of 1752 patients met inclusion criteria, 881 delivering during the daytime, while 871 during the nighttime. There were no differences in demographic maternal variables. There were no differences in the number of patients

  13. Structure and properties of PVDF membrane with PES-C addition via thermally induced phase separation process

    Science.gov (United States)

    Wu, Lishun; Sun, Junfen

    2014-12-01

    Polyvinylidene fluoride (PVDF) membrane and PVDF membrane with phenolphthalein polyethersulfone (PES-C) addition were prepared via thermally induced phase separation (TIPS) method by using diphenyl carbonate (DPC) and dimethyl acetamide (DMAc) as mixed diluents. The effects of coagulation temperature and pre-evaporation time on structure and properties of membranes were studied. The changes of sewage flux in MBR and the attenuation coefficient of sewage flux were investigated. The resistance distributions of PVDF and PVDF/PES-C membranes were compared by resistance analysis. Membrane composition and structure were characterized by ATR-FTIR, TGA, SEM and AFM. The foulant on membranes was analyzed by FTIR. The contact angle of PVDF/PES-C membrane was lower than that of PVDF membrane. A thinner skin layer and a porous cellular support layer formed in PVDF/PES-C membrane and resulted in a higher porosity and pure water flux. The pure water flux and porosity of PVDF/PES-C membrane increased with rising coagulation temperature and decreased with extending pre-evaporation time. The flux attenuation coefficient, the cake layer resistance and internal fouling resistance of PVDF/PES-C membrane in MBR were smaller than those of PVDF membrane in MBR. The FTIR spectrum of foulant on membrane indicated that the foulant on PVDF/PES-C membrane was mostly composed of protein and polysaccharide, while the foulant on pure PVDF membrane included biopolymer clusters besides protein and polysaccharide.

  14. Effect of combination dope composition and evaporation time on the separation performance of cellulose acetate membrane for demak brackish water treatment

    Directory of Open Access Journals (Sweden)

    Kusworo Tutuk Djoko

    2017-01-01

    Full Text Available The coastal areas in Indonesia often have a problem of clean water lack, because the water is classified as brackish water. Therefore, this research investigated the fabrication of CA membranes using phase inversion method for brackish water treatment. Investigation was conducted to study the effect of combination dope composition and evaporation time on separation performance and morphology of the memrbane. Membrane was fabricated by dry-wet phase inversion technique with variation of polymer concentration 17, 18 and 20 wt% in the total solid and evaporation time of 5, 10 and 15 seconds, respectively. The asymmetric membranes were characterized by permeability test through rejection and flux measurements using brackish water as feed. The experimental results from SEM images analysis showed that all the membranes have a thin small porous layer and thicker sub-structure of larger porous layer formed asymmetric membrane. Moreover, the greater polymer concentration is resulting smaller pore size and smaller membrane porosity. The longer evaporation time was also resulted in denser membrane active layer. The best membrane performance was observed at the composition of 20 wt% CA polymer, 1 wt % polyethylene glycol with the solvent evaporation time of 15 seconds.

  15. 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

  16. Macropis fulvipes Venom component Macropin Exerts its Antibacterial and Anti-Biofilm Properties by Damaging the Plasma Membranes of Drug Resistant Bacteria.

    Science.gov (United States)

    Ko, Su Jin; Kim, Min Kyung; Bang, Jeong Kyu; Seo, Chang Ho; Luchian, Tudor; Park, Yoonkyung

    2017-11-29

    The abuse of antibiotics for disease treatment has led to the emergence of multidrug resistant bacteria. Antimicrobial peptides, found naturally in various organisms, have received increasing interest as alternatives to conventional antibiotics because of their broad spectrum antimicrobial activity and low cytotoxicity. In a previous report, Macropin, isolated from bee venom, exhibited antimicrobial activity against both gram-positive and negative bacteria. In the present study, Macropin was synthesized and its antibacterial and anti-biofilm activities were tested against bacterial strains, including gram-positive and negative bacteria, and drug resistant bacteria. Moreover, Macropin did not exhibit hemolytic activity and cytotoxicity to keratinocytes, whereas Melittin, as a positive control, showed very high toxicity. Circular dichroism assays showed that Macropin has an α-helical structure in membrane mimic environments. Macropin binds to peptidoglycan and lipopolysaccharide and kills the bacteria by disrupting their membranes. Moreover, the fractional inhibitory concentration index indicated that Macropin has additive and partially synergistic effects with conventional antibiotics against drug resistant bacteria. Thus, our study suggested that Macropin has potential for use of an antimicrobial agent for infectious bacteria, including drug resistant bacteria.

  17. Spike-timing dependent plasticity in a transistor-selected resistive switching memory

    International Nuclear Information System (INIS)

    Ambrogio, S; Balatti, S; Nardi, F; Facchinetti, S; Ielmini, D

    2013-01-01

    In a neural network, neuron computation is achieved through the summation of input signals fed by synaptic connections. The synaptic activity (weight) is dictated by the synchronous firing of neurons, inducing potentiation/depression of the synaptic connection. This learning function can be supported by the resistive switching memory (RRAM), which changes its resistance depending on the amplitude, the pulse width and the bias polarity of the applied signal. This work shows a new synapse circuit comprising a MOS transistor as a selector and a RRAM as a variable resistance, displaying spike-timing dependent plasticity (STDP) similar to the one originally experienced in biological neural networks. We demonstrate long-term potentiation and long-term depression by simulations with an analytical model of resistive switching. Finally, the experimental demonstration of the new STDP scheme is presented. (paper)

  18. Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans

    DEFF Research Database (Denmark)

    Esmarck, B.; Andersen, J.L.; Olsen, S.

    2001-01-01

    1. Age-associated loss of skeletal muscle mass and strength can partly be counteracted by resistance training, causing a net synthesis of muscular proteins. Protein synthesis is influenced synergistically by postexercise amino acid supplementation, but the importance of the timing of protein intake...... ± S.E.M.)) completed a 12 week resistance training programme (3 times per week) receiving oral protein in liquid form (10 g protein, 7 g carbohydrate, 3 g fat) immediately after (P0) or 2 h after (P2) each training session. Muscle hypertrophy was evaluated by magnetic resonance imaging (MRI) and from...

  19. Comparative study of on-line response time measurement methods for platinum resistance thermometer

    International Nuclear Information System (INIS)

    Zwingelstein, G.; Gopal, R.

    1979-01-01

    This study deals with the in site determination of the response time of platinum resistance sensor. In the first part of this work, two methods furnishing the reference response time of the sensors are studied. In the second part of the work, two methods obtaining the response time without dismounting of the sensor, are studied. A comparative study of the performances of these methods is included for fluid velocities varying from 0 to 10 m/sec, in both laboratory and plant conditions

  20. Real Time Monitoring of Temperature of a Micro Proton Exchange Membrane Fuel Cell

    Science.gov (United States)

    Lee, Chi-Yuan; Lee, Shuo-Jen; Hu, Yuh-Chung; Shih, Wen-Pin; Fan, Wei-Yuan; Chuang, Chih-Wei

    2009-01-01

    Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10−3/°C, respectively. The best experimental performance was 9.37 mW/cm2 at an H2/O2 dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C. PMID:22573963

  1. Real Time Monitoring of Temperature of a Micro Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Chih-Wei Chuang

    2009-03-01

    Full Text Available Silicon micro-hole arrays (Si-MHA were fabricated as a gas diffusion layer (GDL in a micro fuel cell using the micro-electro-mechanical-systems (MEMS fabrication technique. The resistance temperature detector (RTD sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10-3/°C, respectively. The best experimental performance was 9.37 mW/cm2 at an H2/O2 dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C.

  2. 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.

  3. Impact of the β-Lactam Resistance Modifier (−-Epicatechin Gallate on the Non-Random Distribution of Phospholipids across the Cytoplasmic Membrane of Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Helena Rosado

    2015-07-01

    Full Text Available The polyphenol (−-epicatechin gallate (ECg inserts into the cytoplasmic membrane (CM of methicillin-resistant Staphylococcus aureus (MRSA and reversibly abrogates resistance to β-lactam antibiotics. ECg elicits an increase in MRSA cell size and induces thickened cell walls. As ECg partially delocalizes penicillin-binding protein PBP2 from the septal division site, reduces PBP2 and PBP2a complexation and induces CM remodelling, we examined the impact of ECg membrane intercalation on phospholipid distribution across the CM and determined if ECg affects the equatorial, orthogonal mode of division. The major phospholipids of the staphylococcal CM, lysylphosphatidylglycerol (LPG, phosphatidylglycerol (PG, and cardiolipin (CL, were distributed in highly asymmetric fashion; 95%–97% of LPG was associated with the inner leaflet whereas PG (~90% and CL (~80% were found predominantly in the outer leaflet. ECg elicited small, significant changes in LPG distribution. Atomic force microscopy established that ECg-exposed cells divided in similar fashion to control bacteria, with a thickened band of encircling peptidoglycan representing the most recent plane of cell division, less distinct ribs indicative of previous sites of orthogonal division and concentric rings and “knobbles” representing stages of peptidoglycan remodelling during the cell cycle. Preservation of staphylococcal membrane lipid asymmetry and mode of division in sequential orthogonal planes appear key features of ECg-induced stress.

  4. 13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    The purpose of the present study was to examine the short-term effect of dietary specific structured triacylglycerols (MLM, M = 8:0, L = 18:2n-6), LLL and MMM on the fatty acid composition of brush border membrane (BBM) phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Rats were...... fatty acids in the two phospholipid pools. Minor effects on BBM-PC and BBM-PE fatty acid profiles (mole-%) were observed. The present study demonstrated for the first time incorporation of C-13-labeled 18:2n-6 into BBM-PC 2 hours and 6 hours after intragastric administration of L*L*L* or ML...

  5. A real-time PCR antibiogram for drug-resistant sepsis.

    Directory of Open Access Journals (Sweden)

    John R Waldeisen

    Full Text Available Current molecular diagnostic techniques for susceptibility testing of septicemia rely on genotyping for the presence of known resistance cassettes. This technique is intrinsically vulnerable due to the inability to detect newly emergent resistance genes. Traditional phenotypic susceptibility testing has always been a superior method to assay for resistance; however, relying on the multi-day growth period to determine which antimicrobial to administer jeopardizes patient survival. These factors have resulted in the widespread and deleterious use of broad-spectrum antimicrobials. The real-time PCR antibiogram, described herein, combines universal phenotypic susceptibility testing with the rapid diagnostic capabilities of PCR. We have developed a procedure that determines susceptibility by monitoring pathogenic load with the highly conserved 16S rRNA gene in blood samples exposed to different antimicrobial drugs. The optimized protocol removes heme and human background DNA from blood, which allows standard real-time PCR detection systems to be employed with high sensitivity (<100 CFU/mL. Three strains of E. coli, two of which were antimicrobial resistant, were spiked into whole blood and exposed to three different antibiotics. After real-time PCR-based determination of pathogenic load, a ΔC(t<3.0 between untreated and treated samples was found to indicate antimicrobial resistance (P<0.01. Minimum inhibitory concentration was determined for susceptible bacteria and pan-bacterial detection was demonstrated with 3 gram-negative and 2 gram-positive bacteria. Species identification was performed via analysis of the hypervariable amplicons. In summary, we have developed a universal diagnostic phenotyping technique that assays for the susceptibility of drug-resistant septicemia with the speed of PCR. The real-time PCR antibiogram achieves detection, susceptibility testing, minimum inhibitory concentration determination, and identification in less than 24

  6. ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY

    International Nuclear Information System (INIS)

    Myers, D.A.; Rucker, D.F.; Fink, J.B.; Loke, M.H.

    2009-01-01

    Highly industrialized areas pose challenges for surface electrical resistivity characterization due to metallic infrastructure. The infrastructure is typically more conductive than the desired targets and will mask the deeper subsurface information. These challenges may be minimized if steel-cased wells are used as long electrodes in the area near the target. We demonstrate a method of using long electrodes to electrically monitor a simulated leak from an underground storage tank with both synthetic examples and a field demonstration. The synthetic examples place a simple target of varying electrical properties beneath a very low resistivity layer. The layer is meant to replicate the effects of infrastructure. Both surface and long electrodes are tested on the synthetic domain. The leak demonstration for the field experiment is simulated by injecting a high conductivity fluid in a perforated well within the S tank farm at Hanford, and the resistivity measurements are made before and after the leak test. All data are processed in four dimensions, where a regularization procedure is applied in both the time and space domains. The synthetic test case shows that the long electrode ERM could detect relative changes in resistivity that are commensurate with the differing target properties. The surface electrodes, on the other hand, had a more difficult time matching the original target's footprint. The field results shows a lowered resistivity feature develop south of the injection site after cessation of the injections. The time lapsed regularization parameter has a strong influence on the differences in inverted resistivity between the pre and post injection datasets, but the interpretation of the target is consistent across all values of the parameter. The long electrode ERM method may provide a tool for near real-time monitoring of leaking underground storage tanks.

  7. ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    MYERS DA; RUCKER DF; FINK JB; LOKE MH

    2009-12-16

    Highly industrialized areas pose challenges for surface electrical resistivity characterization due to metallic infrastructure. The infrastructure is typically more conductive than the desired targets and will mask the deeper subsurface information. These challenges may be minimized if steel-cased wells are used as long electrodes in the area near the target. We demonstrate a method of using long electrodes to electrically monitor a simulated leak from an underground storage tank with both synthetic examples and a field demonstration. The synthetic examples place a simple target of varying electrical properties beneath a very low resistivity layer. The layer is meant to replicate the effects of infrastructure. Both surface and long electrodes are tested on the synthetic domain. The leak demonstration for the field experiment is simulated by injecting a high conductivity fluid in a perforated well within the S tank farm at Hanford, and the resistivity measurements are made before and after the leak test. All data are processed in four dimensions, where a regularization procedure is applied in both the time and space domains. The synthetic test case shows that the long electrode ERM could detect relative changes in resistivity that are commensurate with the differing target properties. The surface electrodes, on the other hand, had a more difficult time matching the original target's footprint. The field results shows a lowered resistivity feature develop south of the injection site after cessation of the injections. The time lapsed regularization parameter has a strong influence on the differences in inverted resistivity between the pre and post injection datasets, but the interpretation of the target is consistent across all values of the parameter. The long electrode ERM method may provide a tool for near real-time monitoring of leaking underground storage tanks.

  8. The influence of resistance training on the critical power function & time to fatigue at critical power.

    Science.gov (United States)

    Bishop, D; Jenkins, D G

    1996-12-01

    The present study examined whether a six-week resistance training program would influence the critical power (CP) function, time to exhaustion (TE) at CP and/or peak oxygen uptake (VO2 peak). The CP function is believed to provide an index of endurance ability (CP given by the slope), and anaerobic work capacity (the y-intercept). Eight healthy, untrained males undertook lower-body resistance training (90 min/day, 3-4 times/wk) for six weeks; eight controls refrained from resistance or endurance training for the same period. Before and immediately following the training period, subjects completed three trials to determine their CP function, a test of VO2 peak, a one-repetition maximum (1-RM) leg press test and TE at their CP. Training significantly increased both 1-RM leg press (28.6%, P 0.05) were found. Changes in the y-intercept following resistance training were negatively correlated with changes in the CP (r = -0.94, p < 0.05, N = 8). The present data show that the y-intercept of the CP function is sensitive to, and modified by, six weeks of resistance training. Given that resistance training had no significant influence on CP, TE at CP or VO2 peak, the present study has also shown that six weeks of resistance training will not alter indices of endurance ability. The negative relationship between changes in the y-intercept and CP exposes a potential limitation of the linear CP function when evaluating changes in endurance ability following an intervention which significantly alters the y-intercept.

  9. Effects of exposure time on variations in the structure and hydrophobicity of polyvinylidene fluoride membranes prepared via vapor-induced phase separation

    Science.gov (United States)

    Peng, Yuelian; Fan, Hongwei; Dong, Yajun; Song, Yanna; Han, Hua

    2012-08-01

    The present investigation revealed how the surface morphology and hydrophobicity of polyvinylidene fluoride (PVDF) membranes, which were prepared via a vapor-induced phase separation (VIPS) method, were affected by the exposure time. The mass variation of the cast film was recorded. Membrane morphologies were observed by scanning electron microscopy (SEM) and thermal behaviors of membranes were examined by differential scanning calorimetry (DSC). Wide angle X-ray diffraction (WAXD) was employed to analyze the crystalline structures of the overall membranes and the surface layers. The results showed that different membrane morphologies and hydrophobicities could be obtained by changing the exposure time. A long exposure time facilitated the crystallization process, resulting in the formation of a porous skin and particle morphology, which increased the hydrophobicity of the surface. A short exposure time favored the formation of a digitate macrovoid and dense skin resulting from liquid-liquid phase separation in the immersion process, which reduced surface hydrophobicity. The water permeate flux in vacuum membrane distillation was greatly affected by the membrane porosity and surface hydrophobicity.

  10. Lithological characterization of a contaminated site using Direct current resistivity and time domain Induced Polarization

    DEFF Research Database (Denmark)

    Maurya, Pradip Kumar; Fiandaca, Gianluca; Auken, Esben

    study a large contaminated site in Denmark was investigated using direct current resistivity and time domain induced polarization (DCIP). For this purpose 14 profiles were collected alongside a stream in order to investigate the contamination and delineate the lithological units. 2D inversion using...

  11. Super Resolution Fluorescence Microscopy and Tracking of Bacterial Flotillin (Reggie Paralogs Provide Evidence for Defined-Sized Protein Microdomains within the Bacterial Membrane but Absence of Clusters Containing Detergent-Resistant Proteins.

    Directory of Open Access Journals (Sweden)

    Felix Dempwolff

    2016-06-01

    Full Text Available Biological membranes have been proposed to contain microdomains of a specific lipid composition, in which distinct groups of proteins are clustered. Flotillin-like proteins are conserved between pro-and eukaryotes, play an important function in several eukaryotic and bacterial cells, and define in vertebrates a type of so-called detergent-resistant microdomains. Using STED microscopy, we show that two bacterial flotillins, FloA and FloT, form defined assemblies with an average diameter of 85 to 110 nm in the model bacterium Bacillus subtilis. Interestingly, flotillin microdomains are of similar size in eukaryotic cells. The soluble domains of FloA form higher order oligomers of up to several hundred kDa in vitro, showing that like eukaryotic flotillins, bacterial assemblies are based in part on their ability to self-oligomerize. However, B. subtilis paralogs show significantly different diffusion rates, and consequently do not colocalize into a common microdomain. Dual colour time lapse experiments of flotillins together with other detergent-resistant proteins in bacteria show that proteins colocalize for no longer than a few hundred milliseconds, and do not move together. Our data reveal that the bacterial membrane contains defined-sized protein domains rather than functional microdomains dependent on flotillins. Based on their distinct dynamics, FloA and FloT confer spatially distinguishable activities, but do not serve as molecular scaffolds.

  12. Palmitoylation of SARS-CoV S protein is necessary for partitioning into detergent-resistant membranes and cell-cell fusion but not interaction with M protein

    International Nuclear Information System (INIS)

    McBride, Corrin E.; Machamer, Carolyn E.

    2010-01-01

    Coronaviruses are enveloped RNA viruses that generally cause mild disease in humans. However, the recently emerged coronavirus that caused severe acute respiratory syndrome (SARS-CoV) is the most pathogenic human coronavirus discovered to date. The SARS-CoV spike (S) protein mediates virus entry by binding cellular receptors and inducing fusion between the viral envelope and the host cell membrane. Coronavirus S proteins are palmitoylated, which may affect function. Here, we created a non-palmitoylated SARS-CoV S protein by mutating all nine cytoplasmic cysteine residues. Palmitoylation of SARS-CoV S was required for partitioning into detergent-resistant membranes and for cell-cell fusion. Surprisingly, however, palmitoylation of S was not required for interaction with SARS-CoV M protein. This contrasts with the requirement for palmitoylation of mouse hepatitis virus S protein for interaction with M protein and may point to important differences in assembly and infectivity of these two coronaviruses.

  13. Membrane paradigm

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  14. The Plasma Membrane-Localized Sucrose Transporter IbSWEET10 Contributes to the Resistance of Sweet Potato to Fusarium oxysporum.

    Science.gov (United States)

    Li, Yan; Wang, Yannan; Zhang, Huan; Zhang, Qian; Zhai, Hong; Liu, Qingchang; He, Shaozhen

    2017-01-01

    SWEET (Sugars Will Eventually be Exported Transporter) proteins, a novel family of sugar transporters, mediate the diffusion of sugars across cell membranes and acts as key players in sucrose phloem loading. Manipulation of SWEET genes in plants leads to various effects on resistance to biotic and abiotic stresses due to disruption of sugar efflux and changes in sugar distribution. In this study, a member of the SWEET gene family, IbSWEET10 , was cloned from the sweet potato line ND98. mRNA expression analysis in sweet potato and promoter β-Glucuronidase analysis in Arabidopsis showed that IbSWEET10 is highly expressed in leaves, especially in vascular tissue. Transient expression in tobacco epidermal cells revealed plasma membrane localization of IbSWEET10, and heterologous expression assays in yeast indicated that IbSWEET10 encodes a sucrose transporter. The expression level of IbSWEET10 was significantly up-regulated in sweet potato infected with Fusarium oxysporum Schlecht. f. sp. batatas. Further characterization revealed IbSWEET10 -overexpressing sweet potato lines to be more resistant to F. oxysporum , exhibiting better growth after infection compared with the control; conversely, RNA interference (RNAi) lines showed the opposite results. Additionally, the sugar content of IbSWEET10 -overexpression sweet potato was significantly reduced, whereas that in RNAi plants was significantly increased compared with the control. Therefore, we suggest that the reduction in sugar content caused by IbSWEET10 overexpression is the major reason for the enhanced F. oxysporum resistance of the transgenic plants. This is the first report that the IbSWEET10 transporter contributes to the resistance of sweet potato to F. oxysporum . The IbSWEET10 gene has the great potential to be used for improving the resistance to F. oxysporum in sweet potato and other plants.

  15. Fitting membrane resistance along with action potential shape in cardiac myocytes improves convergence: application of a multi-objective parallel genetic algorithm.

    Directory of Open Access Journals (Sweden)

    Jaspreet Kaur

    Full Text Available Fitting parameter sets of non-linear equations in cardiac single cell ionic models to reproduce experimental behavior is a time consuming process. The standard procedure is to adjust maximum channel conductances in ionic models to reproduce action potentials (APs recorded in isolated cells. However, vastly different sets of parameters can produce similar APs. Furthermore, even with an excellent AP match in case of single cell, tissue behaviour may be very different. We hypothesize that this uncertainty can be reduced by additionally fitting membrane resistance (Rm. To investigate the importance of Rm, we developed a genetic algorithm approach which incorporated Rm data calculated at a few points in the cycle, in addition to AP morphology. Performance was compared to a genetic algorithm using only AP morphology data. The optimal parameter sets and goodness of fit as computed by the different methods were compared. First, we fit an ionic model to itself, starting from a random parameter set. Next, we fit the AP of one ionic model to that of another. Finally, we fit an ionic model to experimentally recorded rabbit action potentials. Adding the extra objective (Rm, at a few voltages to the AP fit, lead to much better convergence. Typically, a smaller MSE (mean square error, defined as the average of the squared error between the target AP and AP that is to be fitted was achieved in one fifth of the number of generations compared to using only AP data. Importantly, the variability in fit parameters was also greatly reduced, with many parameters showing an order of magnitude decrease in variability. Adding Rm to the objective function improves the robustness of fitting, better preserving tissue level behavior, and should be incorporated.

  16. Correlation between ceftriaxone resistance of Salmonella enterica serovar Typhimurium and expression of outer membrane proteins OmpW and Ail/OmpX-like protein, which are regulated by BaeR of a two-component system.

    Science.gov (United States)

    Hu, Wensi S; Li, Pei-Chuan; Cheng, Chao-Yin

    2005-09-01

    Mutant 7F2 of Salmonella enterica serovar Typhimurium has a transposon inserted in the regulator gene baeR of a two-component system and showed a more-than-fourfold reduction in resistance to ceftriaxone. Complementation analysis suggested an association among the outer membrane proteins OmpW and STM3031, ceftriaxone resistance, and baeR.

  17. Digital pulley reconstruction with expanded polytetrafluoroethylene (PTFE) membrane at the time of tenorrhaphy in an experimental animal model.

    Science.gov (United States)

    Semer, N B; Bartle, B K; Telepun, G M; Goldberg, N H

    1992-05-01

    Digital pulley reconstruction with a synthetic material, PTFE membrane, was compared with suture repair of the native A3 pulley at the time of tenorrhaphy in the chicken model. The surgically treated foot was immobilized in flexion for either 28 or 35 days and then allowed full ambulation for periods of up to 42 days postoperatively. At sacrifice digits underwent range-of-motion testing, and the pulley and tenorrhaphy sites were explored. No disruptions were noted in the reconstructed PTFE pulleys. The number of tenorrhaphy disruptions was similar between the PTFE pulley group (11%) and the suture repair of the native pulley group (14%). No decrease in range of motion was demonstrated in the PTFE pulley digits, and no deleterious effect of increasing immobilization time (35 days versus 28 days) was noted. The results indicate that this synthetic pulley did not interfere with normal tendon healing processes. PTFE membrane may prove to be a promising reconstructive alternative when the native pulley is irreparably damaged.

  18. Electron in the field of flexural vibrations of a membrane: Quantum time, magnetic oscillations, and coherence breaking

    Energy Technology Data Exchange (ETDEWEB)

    Gornyi, I. V. [Karlsruhe Institute of Technology, Institut für Nanotechnologie (Germany); Dmitriev, A. P., E-mail: apd1812@hotmail.com [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Mirlin, A. D.; Protopopov, I. V. [Karlsruhe Institute of Technology, Institut für Nanotechnologie (Germany)

    2016-08-15

    We have studied the motion of an electron in a membrane under the influence of flexural vibrations with a correlator that decreases upon an increase in the distance in accordance with the law r–{sup 2η}. We have conducted a detailed consideration of the case with η < 1/2, in which the perturbation theory is inapplicable, even for an arbitrarily weak interaction. It is shown that, in this case, reciprocal quantum time 1/τ{sub q} is proportional to g{sup 1/(1–η)}T{sup (2–η)/(2–2η)}, where g is the electron–phonon interaction constant and T is the temperature. The method developed here is applied for calculating the electron density of states in a magnetic field perpendicular to the membrane. In particular, it is shown that the Landau levels in the regime with ω{sub c}τ{sub q} » 1 have a Gaussian shape with a width that depends on the magnetic field as B{sup η}. In addition, we calculate the time τ{sub φ} of dephasing of the electron wave function that emerges due to the interaction with flexural phonons for η < 1/2. It has been shown that, in several temperature intervals, quantity 1/τ{sub φ} can be expressed by various power functions of the electron–phonon interaction constant, temperature, and electron energy.

  19. A Modified Time-Delay Addition Method to Extract Resistive Leakage Current of MOSA

    Science.gov (United States)

    Khodsuz, Masume; Mirzaie, Mohammad

    2016-12-01

    Metal oxide surge arresters are one of the most important equipment for power system protection against switching and lightning over-voltages. High-energy stresses and environmental features are the main factors which degrade surge arresters. In order to verify surge arresters good condition, their monitoring is necessary. The majority of surge arrester monitoring techniques is based on total leakage current decomposition of their capacitive and resistive components. This paper introduces a new approach based on time-delay addition method to extract the resistive current from the total leakage current without measuring voltage signal. Surge arrester model for calculating leakage current has been performed in ATP-EMTP. In addition, the signal processing has been done using MATLAB software. To show the accuracy of the proposed method, experimental tests have been performed to extract resistive leakage current by the proposed method.

  20. Final technical report. A sodium-cycle based organism with improved membrane resistance aimed at increasing the efficiency of energy biotransformations

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Kim

    2001-06-01

    The aim of the project was to express in E. coli components that would allow a formation of oxidative phosphorylation based on a sodium cycle. This would improve the resistance of cells to organic solvents, detergents and other toxins. The author cloned and expressed the nqr operon from H. influenzae in E. coli. Experiments with membrane vesicles indicated the presence of the functional recombinant sodium pumping NADH dehydrogenase. A gene for a hybrid E. coli/P.modestum ATPase was constructed which will enable one to co-express a sodium ATPsynthase together with a sodium NADH dehydrogenase.

  1. Final technical report. A sodium-cycle based organism with improved membrane resistance aimed at increasing the efficiency of energy biotransformations

    International Nuclear Information System (INIS)

    Lewis, Kim

    2001-01-01

    The aim of the project was to express in E. coli components that would allow a formation of oxidative phosphorylation based on a sodium cycle. This would improve the resistance of cells to organic solvents, detergents and other toxins. The author cloned and expressed the nqr operon FR-om H. influenzae in E. coli. Experiments with membrane vesicles indicated the presence of the functional recombinant sodium pumping NADH dehydrogenase. A gene for a hybrid E. coli/P.modestum ATPase was constructed which will enable one to co-express a sodium ATPsynthase together with a sodium NADH dehydrogenase

  2. Active Probes for Imaging Membrane Dynamics of Live Cells with High Spatial and Temporal Resolution over Extended Time Scales and Areas.

    Science.gov (United States)

    Wang, Huaimin; Feng, Zhaoqianqi; Del Signore, Steven J; Rodal, Avital A; Xu, Bing

    2018-03-14

    Despite the advancement of molecular imaging techniques, there is an unmet need for probes for direct imaging of membrane dynamics of live cells. Here we report a novel type of active (or enzyme responsive) probes to directly image membrane dynamics of live cells with high spatial and temporal resolution over extended time scales and areas. Because lipid rafts enrich cholesterols and GPI-anchored enzymes (e.g., ectophosphatases), we design probes that consist of an enzymatic trigger, a fluorophore, and a cholesterol that are affinitive to the cell membrane. Being water-soluble and as the substrate of ectophosphatase, these cell compatible probes preferentially and rapidly assemble in plasma membrane, exhibit strong fluorescence, work at micromolar concentrations, and easily achieve high resolution monitoring of nanoscale heterogeneity in membranes of live cells, the release of exosomes, and the membrane dynamics of live cells. This work provides a facile means to link membrane dynamics and heterogeneity to cellular processes for understanding the interactions between membranes and proteins.

  3. Time-wise change in neck pain in response to rehabilitation with specific resistance training

    DEFF Research Database (Denmark)

    Zebis, Mette Kreutzfeldt; Andersen, Christoffer H; Sundstrup, Emil

    2014-01-01

    Purpose To determine the time-wise effect of specific resistance training on neck pain among industrial technicians with frequent neck pain symptoms. Methods Secondary analysis of a parallel-group cluster randomized controlled trial of 20 weeks performed at two large industrial production units...... in Copenhagen, Denmark. Women with neck pain >30 mm VAS (N = 131) were included in the present analysis. The training group (N = 77) performed specific resistance training for the neck/shoulder muscles three times a week, and the control group (N = 54) received advice to stay active. Participants of both groups...... to 20). The time-wise change in pain showed three phases; a rapid decrease in the training group compared with the control group during the initial 7 weeks, a slower decrease in pain during the following weeks (week 8–15), and a plateau during the last weeks (week 16–20). Adherence to training followed...

  4. Freeze core sampling to validate time-lapse resistivity monitoring of the hyporheic zone.

    Science.gov (United States)

    Toran, Laura; Hughes, Brian; Nyquist, Jonathan; Ryan, Robert

    2013-01-01

    A freeze core sampler was used to characterize hyporheic zone storage during a stream tracer test. The pore water from the frozen core showed tracer lingered in the hyporheic zone after the tracer had returned to background concentration in collocated well samples. These results confirmed evidence of lingering subsurface tracer seen in time-lapse electrical resistivity tomographs. The pore water exhibited brine exclusion (ion concentrations in ice lower than source water) in a sediment matrix, despite the fast freezing time. Although freeze core sampling provided qualitative evidence of lingering tracer, it proved difficult to quantify tracer concentration because the amount of brine exclusion during freezing could not be accurately determined. Nonetheless, the additional evidence for lingering tracer supports using time-lapse resistivity to detect regions of low fluid mobility within the hyporheic zone that can act as chemically reactive zones of importance in stream health. © 2012, The Author(s). GroundWater © 2012, National Ground Water Association.

  5. Fouling Resistant CA/PVA/TiO2Imprinted Membranes for Selective Recognition and Separation Salicylic Acid from Waste Water.

    Science.gov (United States)

    Yu, Xiaopeng; Mi, Xueyang; He, Zhihui; Meng, Minjia; Li, Hongji; Yan, Yongsheng

    2017-01-01

    Highly selective cellulose acetate (CA)/poly (vinyl alcohol) (PVA)/titanium dioxide (TiO 2 ) imprinted membranes were synthesized by phase inversion and dip coating technique. The CA blend imprinted membrane was synthesized by phase inversion technique with CA as membrane matrix, polyethyleneimine (PEI) as the functional polymer, and the salicylic acid (SA) as the template molecule. The CA/PVA/TiO 2 imprinted membranes were synthesized by dip coating of CA blend imprinted membrane in PVA and different concentration (0.05, 0.1, 0.2, 0.4 wt %) of TiO 2 nanoparticles aqueous solution. The SEM analysis showed that the surface morphology of membrane was strongly influenced by the concentration of TiO 2 nanoparticles. Compared with CA/PVA-TiO 2 (0.05, 0.1, 0.2%)-MIM, the CA/PVA-TiO 2 (0.4%)-MIM possessed higher membrane flux, kinetic equilibrium adsorption amount, binding capacity and better selectivity for SA. It was found that the pseudo-second-order kinetic model was studied to describe the kinetic of CA/PVA-TiO 2 (0.2%)-MIM judging by multiple regression analysis. Adsorption isotherm analysis indicated that the maximum adsorption capacity for SA were 24.43 mg g -1 . Moreover, the selectivity coefficients of CA/PVA-TiO 2 (0.2%)-MIM for SA relative to p -hydroxybenzoic acid ( p -HB) and methyl salicylate (MS) were 3.87 and 3.55, respectively.

  6. Real-time examination of aminoglycoside activity towards bacterial mimetic membranes using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D).

    Science.gov (United States)

    Joshi, Tanmaya; Voo, Zhi Xiang; Graham, Bim; Spiccia, Leone; Martin, Lisandra L

    2015-02-01

    The rapid increase in multi-drug resistant bacteria has resulted in previously discontinued treatments being revisited. Aminoglycosides are effective "old" antibacterial agents that fall within this category. Despite extensive usage and understanding of their intracellular targets, there is limited mechanistic knowledge regarding how aminoglycosides penetrate bacterial membranes. Thus, the activity of two well-known aminoglycosides, kanamycin A and neomycin B, towards a bacterial mimetic membrane (DMPC:DMPG (4:1)) was examined using a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). The macroscopic effect of increasing the aminoglycoside concentration showed that kanamycin A exerts a threshold response, switching from binding to the membrane to disruption of the surface. Neomycin B, however, disrupted the membrane at all concentrations examined. At concentrations above the threshold value observed for kanamycin A, both aminoglycosides revealed similar mechanistic details. That is, they both inserted into the bacterial mimetic lipid bilayer, prior to disruption via loss of materials, presumably aminoglycoside-membrane composites. Depth profile analysis of this membrane interaction was achieved using the overtones of the quartz crystal sensor. The measured data is consistent with a two-stage process in which insertion of the aminoglycoside precedes the 'detergent-like' removal of membranes from the sensor. The results of this study contribute to the insight required for aminoglycosides to be reconsidered as active antimicrobial agents/co-agents by providing details of activity at the bacterial membrane. Kanamycin and neomycin still offer potential as antimicrobial therapeutics for the future and the QCM-D method illustrates great promise for screening new antibacterial or antiviral drug candidates. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Investigations on the corrosion resistance of metallic bipolar plates (BPP) in proton exchange membrane fuel cells (PEMFC) - understanding the effects of material, coating and manufacturing

    Science.gov (United States)

    Dur, Ender

    Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems are promising technology for contributing to meet the deficiency of world`s clean and sustainable energy requirements in the near future. Metallic bipolar plate (BPP) as one of the most significant components of PEMFC device accounts for the largest part of the fuel cell`s stack. Corrosion for metallic bipolar plates is a critical issue, which influences the performance and durability of PEMFC. Corrosion causes adverse impacts on the PEMFC`s performance jeopardizing commercialization. This research is aimed at determining the corrosion resistance of metallic BPPs, particularly stainless steels, used in PEMFC from different aspects. Material selection, coating selection, manufacturing process development and cost considerations need to be addressed in terms of the corrosion behavior to justify the use of stainless steels as a BPP material in PEMFC and to make them commercially feasible in industrial applications. In this study, Ti, Ni, SS304, SS316L, and SS 430 blanks, and BPPs comprised of SS304 and SS316L were examined in terms of the corrosion behavior. SS316L plates were coated to investigate the effect of coatings on the corrosion resistance performance. Stamping and hydroforming as manufacturing processes, and three different coatings (TiN, CrN, ZrN) applied via the Physical Vapor Deposition (PVD) method in three different thicknesses were selected to observe the effects of manufacturing processes, coating types and coating thicknesses on the corrosion resistance of BPP, respectively. Uncoated-coated blank and formed BPP were subjected to two different corrosion tests: potentiostatic and potentiodynamic. Some of the substantial results: 1- Manufacturing processes have an adverse impact on the corrosion resistance. 2- Hydroformed plates have slightly higher corrosion resistance than stamped samples. 3- BPPs with higher channel size showed better corrosion resistance. 4- Since none of the uncoated samples

  8. Resistivity structures imaging using time-domain electromagnetic data; TDEM ho ni yoru chika hiteiko kozo no imaging

    Energy Technology Data Exchange (ETDEWEB)

    Noguchi, K. [Waseda University, Tokyo (Japan). School of Science and Engineering; Endo, M. [Waseda University, Tokyo (Japan)

    1996-10-01

    The kernel function for transient vertical magnetic dipole was defined for semi-infinite uniform medium, and the 1-D imaging algorithm by TDEM (time-domain electromagnetic) method was developed for underground resistivity structure. Electromagnetic migration method directly images sectional resistivity profiles from the data observed by frequency-domain MT method, and determines underground resistivity profiles by integral equation of MT field using the concept of return travel time in reflection seismic exploration. The method reported in this paper is also one of the EM migration methods. The imaging algorithm of 2-D resistivity structure was developed by correcting 1-D imaging in consideration of the effect of 2-D anomaly on 1-D imaging (the resistivity of anomaly can be obtained from the resistivity contrast between anomaly and medium). The conventional methods require enormous forward computation, while this method can obtain underground resistivity structure in extremely short computation time, resulting in superior practicability. 12 refs., 7 figs.

  9. Effect of swine manure application timing on the persistence and transport of antibiotic-resistant Enterococcus and resistance genes

    Science.gov (United States)

    Swine manure applied to agricultural fields may lead to the transport of antibiotic resistant bacteria and antibiotic resistance genes to freshwater systems. Enterococci were studied because they are fecal indicator bacteria associated with manure. Resistance genes include genes from live cells, dea...

  10. Environmental Monitoring Of Leaks Using Time Lapsed Long Electrode Electrical Resistivity

    International Nuclear Information System (INIS)

    Rucker, D.F.; Fink, J.B.; Loke, M.H.; Myers, D.A.

    2009-01-01

    Highly industrialized areas pose significant challenges for surface based electrical resistivity characterization and monitoring due to the high degree of metallic infrastructure. The infrastructure is typically several orders of magnitude more conductive than the desired targets, preventing the geophysicist from obtaining a clear picture of the subsurface. These challenges may be minimized if steel-cased wells are used as long electrodes. We demonstrate a method of using long electrodes in a complex nuclear waste facility to monitor a simulated leak from an underground storage tank. The leak was simulated by injecting high conductivity fluid in a perforated well and the resistivity measurements were made before and after the leak test. The data were processed in four dimensions, where a regularization procedure was applied in both the time and space domains. The results showed a lowered resistivity feature develop south of the injection site. The time lapsed regularization parameter had a strong influence on the differences in inverted resistivity between the pre and post datasets, potentially making calibration of the results to specific hydrogeologic parameters difficult.

  11. Application of the nanocomposite membrane as electrolyte of proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Mahreni

    2010-01-01

    Hydrogen fuel cells proton exchange membrane fuel cell (PEMFC) is currently still in development and commercialization. Several barriers to the commercialization of these Nafion membrane as electrolyte is its very sensitive to humidity fluctuation. Nafion must be modified by making a composite Nafion-SiO 2 -HPA to increase electrolyte resistance against humidity fluctuations during the cell used. Research carried out by mixing Nafion solution with Tetra Ethoxy Ortho Silicate (TEOS) and conductive materials is phosphotungstic acid (PWA) by varying the ratio of Nafion, TEOS and PWA. The membrane is produced by heating a mixture of Nafion, TEOS and PWA by varying the evaporation temperature, time and annealing temperature to obtain the transparent membrane. The resulting membrane was analyzed its physical, chemical and electrochemical properties by applying the membrane as electrolyte of PEMFC at various humidity and temperature of operation. The results showed that at low temperatures (30-90 °C) and high humidity at 100 % RH, pure Nafion membrane is better than composite membrane (Nafion-SiO 2 -PWA), but at low humidity condition composite membrane is better than the pure Nafion membrane. It can be concluded that the composite membranes of (Nafion-SiO 2 -PWA) can be used as electrolyte of PEMFC operated at low humidity (40 % RH) and temperature between (30-90 °C). (author)

  12. [The roles of active efflux system overexpression and outer membrane protein OprD deficiency or loss in carbapenem resistance of Pseudomonas aeruginosa].

    Science.gov (United States)

    Yi, Mei-ying; Wang, Peng-yuan; Huang, Han-ju; Liu, Yu-cun

    2006-02-21

    To investigate the mechanisms of carbapenem resistance in Pseudomonas aeruginosa (PA). Forty-nine strains of PA were isolated from surgical intensive care unit during a period of 3 years. The levels of outer membrane protein OprD and OprN were measured by Western blotting. RT-PCR was used to measure the transcription levels of mexA gene. The metallo-beta-lactamase genes IMP and VIM and the negative regulator gene mexR for mexAB-OprM operon were amplified. The DNA fragments were sequenced by automated ABI PRISM 3700 sequencer. 42 of the 49 strains were resistant to carbapenem. 23 of the 42 strains showed loss of OprD and were all resistant to imipenem, but only one strain was resistant to meropenem. 18 of the 42 strains had a decreased OprD expression, 17 of which were resistant to Imipenem, and 3 were resistant to meropenem as well. 7 strains expressed OprD, all of which were sensitive to carbapenem. 27 strains overexpressed the mexAB-OprM. The resistant rate to imipenem of the mexAB-OprM overexpression group was 86.4%, not significantly different from that of the mexAB-OprM low expression group (81.5%, chi(2) = 0.005, P = 0.943). But the resistant rate to meropenem of the mexAB-OprM overexpression group was 44.4%, statistically higher than that of mexAB-OprM low expression group (13.6%, chi(2) = 5.417, P = 0.020). Nucleotide sequences and deduced amino acid sequences analysis revealed that eight strains overexpressed mexAB-OprM carried mutations in mexR gene, 7 of which had amino acid substitutions in MexR protein, and one of which had terminal code at the position of amino acid 32. 14 strains were found expressing OprN. Neither IMP gene nor VIM gene was found in the isolates. In the clinical strains from SICU, the imipenem resistance is mainly mediated by OprD deficiency or loss. Overexpression of MexAB-OprM is the primary mechanism of meropenem resistance, which is upregulated by mutations in mexR gene. Metallo-beta-lactamases IMP and VIM are rarely seen.

  13. The Membrane-Anchored BOTRYTIS-INDUCED KINASE1 Plays Distinct Roles in Arabidopsis Resistance to Necrotrophic and Biotrophic PathogensW⃞

    Science.gov (United States)

    Veronese, Paola; Nakagami, Hirofumi; Bluhm, Burton; AbuQamar, Synan; Chen, Xi; Salmeron, John; Dietrich, Robert A.; Hirt, Heribert; Mengiste, Tesfaye

    2006-01-01

    Plant resistance to disease is controlled by the combination of defense response pathways that are activated depending on the nature of the pathogen. We identified the Arabidopsis thaliana BOTRYTIS-INDUCED KINASE1 (BIK1) gene that is transcriptionally regulated by Botrytis cinerea infection. Inactivation of BIK1 causes severe susceptibility to necrotrophic fungal pathogens but enhances resistance to a virulent strain of the bacterial pathogen Pseudomonas syringae pv tomato. The response to an avirulent bacterial strain is unchanged, limiting the role of BIK1 to basal defense rather than race-specific resistance. The jasmonate- and ethylene-regulated defense response, generally associated with resistance to necrotrophic fungi, is attenuated in the bik1 mutant based on the expression of the plant defensin PDF1.2 gene. bik1 mutants show altered root growth, producing more and longer root hairs, demonstrating that BIK1 is also required for normal plant growth and development. Whereas the pathogen responses of bik1 are mostly dependent on salicylic acid (SA) levels, the nondefense responses are independent of SA. BIK1 is membrane-localized, suggesting possible involvement in early stages of the recognition or transduction of pathogen response. Our data suggest that BIK1 modulates the signaling of cellular factors required for defense responses to pathogen infection and normal root hair growth, linking defense response regulation with that of growth and development. PMID:16339855

  14. Designing and Validating Ternary Pd Alloys for Optimum Sulfur/Carbon Resistance in Hydrogen Separation and Carbon Capture Membrane Systems Using High-Throughput Combinatorial Methods

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Amanda [Pall Corporation, Port Washington, NY (United States); Zhao, Hongbin [Pall Corporation, Port Washington, NY (United States); Hopkins, Scott [Pall Corporation, Port Washington, NY (United States)

    2014-12-01

    This report summarizes the work completed under the U.S. Department of Energy Project Award No.: DE-FE0001181 titled “Designing and Validating Ternary Pd Alloys for Optimum Sulfur/Carbon Resistance in Hydrogen Separation and Carbon Capture Membrane Systems Using High-Throughput Combinatorial Methods.” The project started in October 1, 2009 and was finished September 30, 2014. Pall Corporation worked with Cornell University to sputter and test palladium-based ternary alloys onto silicon wafers to examine many alloys at once. With the specialized equipment at Georgia Institute of Technology that analyzed the wafers for adsorbed carbon and sulfur species six compositions were identified to have resistance to carbon and sulfur species. These compositions were deposited on Pall AccuSep® supports by Colorado School of Mines and then tested in simulated synthetic coal gas at the Pall Corporation. Two of the six alloys were chosen for further investigations based on their performance. Alloy reproducibility and long-term testing of PdAuAg and PdZrAu provided insight to the ability to manufacture these compositions for testing. PdAuAg is the most promising alloy found in this work based on the fabrication reproducibility and resistance to carbon and sulfur. Although PdZrAu had great initial resistance to carbon and sulfur species, the alloy composition has a very narrow range that hindered testing reproducibility.

  15. Analysis of the membrane proteome of ciprofloxacin-resistant macrophages by stable isotope labeling with amino acids in cell culture (SILAC.

    Directory of Open Access Journals (Sweden)

    Nancy E Caceres

    Full Text Available Overexpression of multidrug transporters is a well-established mechanism of resistance to chemotherapy, but other changes may be co-selected upon exposure to drugs that contribute to resistance. Using a model of J774 macrophages made resistant to the fluoroquinolone antibiotic ciprofloxacin and comparing it with the wild-type parent cell line, we performed a quantitative proteomic analysis using the stable isotope labeling with amino acids in cell culture technology coupled with liquid chromatography electrospray ionization Fourier transform tandem mass spectrometry (LC-ESI-FT-MS/MS on 2 samples enriched in membrane proteins (fractions F1 and F2 collected from discontinuous sucrose gradient. Nine hundred proteins were identified with at least 3 unique peptides in these 2 pooled fractions among which 61 (F1 and 69 (F2 showed a significantly modified abundance among the 2 cell lines. The multidrug resistance associated protein Abcc4, known as the ciprofloxacin efflux transporter in these cells, was the most upregulated, together with Dnajc3, a protein encoded by a gene located downstream of Abcc4. The other modulated proteins are involved in transport functions, cell adhesion and cytoskeleton organization, immune response, signal transduction, and metabolism. This indicates that the antibiotic ciprofloxacin is able to trigger a pleiotropic adaptative response in macrophages that includes the overexpression of its efflux transporter.

  16. 3-D time-lapse electrical resistivity monitoring of injected CO2 in a shallow aquifer

    DEFF Research Database (Denmark)

    Doetsch, Joseph A. J.A.; Auken, Esben; Christiansen, Anders Vest C A.V.C.

    2013-01-01

    Contamination of potable groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment, we investigate if surface electrical resistivity tomography (ERT) can detect dissolved CO2 in a shallow aquifer. For this purpose, we injected CO2 at a depth of 5...... inversion reveals the geology at the site consisting of aeolian sands near the surface and glacial sands below 5 m depth. Time-lapse inversions clearly image the dissolved CO2 plume with decreased electrical resistivity values. We can follow the CO2 plume as it spreads and moves with the groundwater...... and 10 m and monitored its migration using 320 surface electrodes on a 126 m × 20 m grid. A fully automated acquisition system continuously collected data and uploaded it into an online database. The large amount of data allows for time-series analysis for data quality and noise estimation. A baseline...

  17. Photobleaching kinetics and time-integrated emission of fluorescent probes in cellular membranes

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Christensen, Tanja; Solanko, Lukasz Michal

    2014-01-01

    Since the pioneering work of Hirschfeld, it is known that time-integrated emission (TiEm) of a fluorophore is independent of fluorescence quantum yield and illumination intensity. Practical implementation of this important result for determining exact probe distribution in living cells is often...... rate constants with a memory kernel. This approach results in a time-dependent bleach rate coefficient and is exemplified for fluorescent sterols in restricted intracellular environments, like lipid droplets. We show that for small deviations from the classical exponential bleaching, the TiEm of decay...

  18. Time-Lapse Electrical Resistivity Investigations for Imaging the Grouting Injection in Shallow Subsurface Cavities

    Directory of Open Access Journals (Sweden)

    Muhammad Farooq

    2014-01-01

    Full Text Available The highway of Yongweol-ri, Muan-gun, south-western part of the South Korean Peninsula, is underlain by the abandoned of subsurface cavities, which were discovered in 2005. These cavities lie at shallow depths with the range of 5∼15 meters below the ground surface. Numerous subsidence events have repeatedly occurred in the past few years, damaging infrastructure and highway. As a result of continuing subsidence issues, the Korean Institute of Geosciences and Mineral Resources (KIGAM was requested by local administration to resolve the issue. The KIGAM used geophysical methods to delineate subsurface cavities and improve more refined understanding of the cavities network in the study area. Cement based grouting has been widely employed in the construction industry to reinforce subsurface ground. In this research work, time-lapse electrical resistivity surveys were accomplished to monitor the grouting injection in the subsurface cavities beneath the highway, which have provided a quasi-real-time monitoring for modifying the subsurface cavities related to ground reinforcement, which would be difficult with direct methods. The results obtained from time-lapse electrical resistivity technique have satisfactory imaged the grouting injection experiment in the subsurface cavities beneath the highway. Furthermore, the borehole camera confirmed the presence of grouting material in the subsurface cavities, and hence this procedure increases the mechanical resistance of subsurface cavities below the highway.

  19. Uncoupler resistance in E. coli Tuv and Cuv is due to the exclusion of uncoupler by the outer membrane

    DEFF Research Database (Denmark)

    Haworth, Robert S.; Jensen, Peter Ruhdal; Michelsen, Ole

    1990-01-01

    is freely permeable to both TPP+ and hydroxymethylinulin. Tuv and Cuv are able to exclude these compounds. EDTA treatment was necessary prior to measuring membrane potentials in Tuv and Cuv. Under conditions where Δψ could be measured, uncouplers acted to dissipate Δψ with equal potency in all strains...

  20. Characterization and modelling of VanT: a novel, membrane-bound, serine racemase from vancomycin-resistant Enterococcus gallinarum BM4174.

    Science.gov (United States)

    Arias, C A; Martín-Martinez, M; Blundell, T L; Arthur, M; Courvalin, P; Reynolds, P E

    1999-03-01

    Sequence determination of a region downstream from the vanXYc gene in Enterococcus gallinarum BM4174 revealed an open reading frame, designated vanT, that encodes a 698-amino-acid polypeptide with an amino-terminal domain containing 10 predicted transmembrane segments. The protein contained a highly conserved pyridoxal phosphate attachment site in the C-terminal domain, typical of alanine racemases. The protein was overexpressed in Escherichia coli, and serine racemase activity was detected in the membrane but not in the cytoplasmic fraction after centrifugation of sonicated cells, whereas alanine racemase activity was located almost exclusively in the cytoplasm. When the protein was overexpressed as a polypeptide lacking the predicted transmembrane domain, serine racemase activity was detected in the cytoplasm. The serine racemase activity was partially (64%) inhibited by D-cycloserine, whereas host alanine racemase activity was almost totally inhibited (97%). Serine racemase activity was also detected in membrane preparations of constitutively vancomycin-resistant E. gallinarum BM4174 but not in BM4175, in which insertional inactivation of the vanC-1 D-Ala:D-Ser ligase gene probably had a polar effect on expression of the vanXYc and vanT genes. Comparative modelling of the deduced C-terminal domain was based on the alignment of VanT with the Air alanine racemase from Bacillus stearothermophilus. The model revealed that almost all critical amino acids in the active site of Air were conserved in VanT, indicating that the C-terminal domain of VanT is likely to adopt a three-dimensional structure similar to that of Air and that the protein could exist as a dimer. These results indicate that the source of D-serine for peptidoglycan synthesis in vancomycin-resistant enterococci expressing the VanC phenotype involves racemization of L- to D-serine by a membrane-bound serine racemase.

  1. Investigating time-efficiency of forward masking paradigms for estimating basilar membrane input-output characteristics

    DEFF Research Database (Denmark)

    Fereczkowski, Michal; Jepsen, Morten Løve; Dau, Torsten

    2017-01-01

    appears to be the main drawback of the conventional TMC method. The results from the present study were consistent with the literature when estimating KP levels, but showed some limitations regarding the estimation of the CR values. Perspectives and limitations of both approaches are discussed.......-output (I/O) function have been proposed. However, such measures are very time consuming. The present study investigated possible modifications of the temporal masking curve (TMC) paradigm to improve time and measurement efficiency. In experiment 1, estimates of knee point (KP) and compression ratio (CR......It is well known that pure-tone audiometry does not sufficiently describe individual hearing loss (HL) and that additional measures beyond pure-tone sensitivity might improve the diagnostics of hearing deficits. Specifically, forward masking experiments to estimate basilarmembrane (BM) input...

  2. Imaging rainfall infiltration processes with the time-lapse electrical resistivity imaging method

    Science.gov (United States)

    Jia, Zhengyuan; Jiang, Guoming; Zhang, Guibin; Zhang, Gang

    2017-04-01

    Electrical Resistivity Imaging (ERI) was carried out continuously for ten days to map the subsurface resistivity distribution along a potentially hazardous hillslope at the Jieshou Junior High School in Taoyuan, Taiwan. The inversions confirm the viability of ERI in tracking the movement of groundwater flow and rainfall infiltration by recording the variation of subsurface resistivity distribution. Meanwhile, relative-water-saturation (RWS) maps can be obtained from ERI images via Archie's Law, which provide a more intuitive reflection of the variation of subsurface rainfall infiltration and a more capable means of estimating the stability of a landslide body. What is more, we then found that the averaged RWS is significantly correlated with daily precipitation. Our observations indicate that real-time ERI is effective in monitoring subterraneous rainfall infiltration, and thereby in estimating the stability of a potential landslide body. When the agglomerate rainfall in the landslide slippage surface was infiltrated quickly without sustaining hydraulic pressure along the landslide slippage surface, the probability of landslides occurring was very low. On the contrary, the probability of landslides occurring could be increased due to the overpressure of pore fluids. Keywords Electrical Resistivity Imaging; Depth-of-Investigation; Archie's Law; Landslide Monitoring; Rainfall Infiltration; Preferential Path

  3. Global HIV-1 transmitted drug resistance in the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial

    DEFF Research Database (Denmark)

    Baxter, J D; Dunn, D; White, E

    2015-01-01

    of resistance testing in START trial participants. METHODS: In the Strategic Timing of AntiRetroviral Treatment (START) trial, baseline genotypic resistance testing results were collected at study entry and analysed centrally to determine the prevalence of TDR in the study population. Resistance was based...... on a modified 2009 World Health Organization definition to reflect newer resistance mutations. RESULTS: Baseline resistance testing was available in 1946 study participants. Higher rates of testing occurred in Europe (86.7%), the USA (81.3%) and Australia (89.9%) as compared with Asia (22.2%), South America (1...

  4. Risk factors and timing of default from treatment for non-multidrug-resistant tuberculosis in Moldova.

    Science.gov (United States)

    Jenkins, H E; Ciobanu, A; Plesca, V; Crudu, V; Galusca, I; Soltan, V; Cohen, T

    2013-03-01

    The Republic of Moldova, in Eastern Europe, has among the highest reported nationwide proportions of tuberculosis (TB) patients with multidrug-resistant tuberculosis (MDR-TB) worldwide. Default has been associated with increased mortality and amplification of drug resistance, and may contribute to the high MDR-TB rates in Moldova. To assess risk factors and timing of default from treatment for non-MDR-TB from 2007 to 2010. A retrospective analysis of routine surveillance data on all non-MDR-TB patients reported. A total of 14.7% of non-MDR-TB patients defaulted from treatment during the study period. Independent risk factors for default included sociodemographic factors, such as homelessness, living alone, less formal education and spending substantial time outside Moldova in the year prior to diagnosis; and health-related factors such as human immunodeficiency virus co-infection, greater lung pathology and increasing TB drug resistance. Anti-tuberculosis treatment is usually initiated within an institutional setting in Moldova, and the default risk was highest in the month following the phase of hospitalized treatment (among civilians) and after leaving prison (among those diagnosed while incarcerated). Targeted interventions to increase treatment adherence for patients at highest risk of default, and improving the continuity of care for patients transitioning from institutional to community care may substantially reduce risk of default.

  5. Development of an Internal Real-Time Wireless Diagnostic Tool for a Proton Exchange Membrane Fuel Cell

    Science.gov (United States)

    Lee, Chi-Yuan; Chen, Chia-Hung; Tsai, Chao-Hsuan; Wang, Yu-Syuan

    2018-01-01

    To prolong the operating time of unmanned aerial vehicles which use proton exchange membrane fuel cells (PEMFC), the performance of PEMFC is the key. However, a long-term operation can make the Pt particles of the catalyst layer and the pollutants in the feedstock gas bond together (e.g., CO), so that the catalyst loses reaction activity. The performance decay and aging of PEMFC will be influenced by operating conditions, temperature, flow and CO concentration. Therefore, this study proposes the development of an internal real-time wireless diagnostic tool for PEMFC, and uses micro-electro-mechanical systems (MEMS) technology to develop a wireless and thin (<50 μm) flexible integrated (temperature, flow and CO) microsensor. The technical advantages are (1) compactness and three wireless measurement functions; (2) elastic measurement position and accurate embedding; (3) high accuracy and sensitivity and quick response; (4) real-time wireless monitoring of dynamic performance of PEMFC; (5) customized design and development. The flexible integrated microsensor is embedded in the PEMFC, three important physical quantities in the PEMFC, which are the temperature, flow and CO, can be measured simultaneously and instantly, so as to obtain the authentic and complete reaction in the PEMFC to enhance the performance of PEMFC and to prolong the service life. PMID:29342832

  6. Development of an Internal Real-Time Wireless Diagnostic Tool for a Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Chi-Yuan Lee

    2018-01-01

    Full Text Available To prolong the operating time of unmanned aerial vehicles which use proton exchange membrane fuel cells (PEMFC, the performance of PEMFC is the key. However, a long-term operation can make the Pt particles of the catalyst layer and the pollutants in the feedstock gas bond together (e.g., CO, so that the catalyst loses reaction activity. The performance decay and aging of PEMFC will be influenced by operating conditions, temperature, flow and CO concentration. Therefore, this study proposes the development of an internal real-time wireless diagnostic tool for PEMFC, and uses micro-electro-mechanical systems (MEMS technology to develop a wireless and thin (<50 μm flexible integrated (temperature, flow and CO microsensor. The technical advantages are (1 compactness and three wireless measurement functions; (2 elastic measurement position and accurate embedding; (3 high accuracy and sensitivity and quick response; (4 real-time wireless monitoring of dynamic performance of PEMFC; (5 customized design and development. The flexible integrated microsensor is embedded in the PEMFC, three important physical quantities in the PEMFC, which are the temperature, flow and CO, can be measured simultaneously and instantly, so as to obtain the authentic and complete reaction in the PEMFC to enhance the performance of PEMFC and to prolong the service life.

  7. Development of an Internal Real-Time Wireless Diagnostic Tool for a Proton Exchange Membrane Fuel Cell.

    Science.gov (United States)

    Lee, Chi-Yuan; Chen, Chia-Hung; Tsai, Chao-Hsuan; Wang, Yu-Syuan

    2018-01-13

    To prolong the operating time of unmanned aerial vehicles which use proton exchange membrane fuel cells (PEMFC), the performance of PEMFC is the key. However, a long-term operation can make the Pt particles of the catalyst layer and the pollutants in the feedstock gas bond together (e.g., CO), so that the catalyst loses reaction activity. The performance decay and aging of PEMFC will be influenced by operating conditions, temperature, flow and CO concentration. Therefore, this study proposes the development of an internal real-time wireless diagnostic tool for PEMFC, and uses micro-electro-mechanical systems (MEMS) technology to develop a wireless and thin (<50 μm) flexible integrated (temperature, flow and CO) microsensor. The technical advantages are (1) compactness and three wireless measurement functions; (2) elastic measurement position and accurate embedding; (3) high accuracy and sensitivity and quick response; (4) real-time wireless monitoring of dynamic performance of PEMFC; (5) customized design and development. The flexible integrated microsensor is embedded in the PEMFC, three important physical quantities in the PEMFC, which are the temperature, flow and CO, can be measured simultaneously and instantly, so as to obtain the authentic and complete reaction in the PEMFC to enhance the performance of PEMFC and to prolong the service life.

  8. INFLUENCE OF INCUBATION TIME, GAMMA RAYS AND ELECTRON BEAM ON RADIATION RESISTANCE OF SOME SELECTED PATHOGENS

    International Nuclear Information System (INIS)

    EL-HIFNAWI, H.N.; EL-TABLAWY, S.Y.

    2009-01-01

    The effect of different growth phases on the radiation resistance, antibiotic susceptibility and pathogenicity of certain selected pathogens (Escherichia coli, Candida albicans and Staphylococcus aureus) was studied in mice. The obtained results showed that Escherichia coli was slightly more resistant to gamma radiation in 18 h than 24 h or 48 h but it was relatively more resistant to electron beam in 24 h and 48 h than 18 h. Candida albicans showed radiation resistance nearly the same in all incubation times in the case of gamma radiation while for electron beam, its radiation resistance was slightly more in 24 h and 48 h than in 18 h. On the other hand, Staphylococcus aureus recorded much more resistance to gamma radiation in the 48 h than in 24 h or 18 h whereas in the case of electron beam, it was slightly more resistant in 18 h than in 24 h and 48 h.The antibiotic susceptibility of Escherichia coli reported that the exposure to gamma radiation at 3 kGy and electron beam at 6 kGy increase the susceptibility to the nalidixic acid and nitrofurantoin. When Candida albicans was exposed to 3 kGy gamma radiation and 6 kGy electron beam, the same sensitivity to nystatin was observed in comparison with the unexposed one while the sensitivity of Staphylococcus aureus to some antibiotics (amoxicillin, nitrofurantoin and tetracycline) was decreased after exposure to gamma radiation at 0.75 and 2 kGy and electron beam at 6 kGy, but for other antibiotics (trimethoprim/ sulfamethoxazole), the sensitivity was increased at 6 kGy electron beam.The lethality percent recorded after the oral ingestion of the mice with the unexposed Escherichia coli and Candida albicans were 25% and 100%, respectively, and for 6 kGy exposure to electron beam was 0% . The cotaneous disease and abscesses caused by the intradermal injection of the mice with unexposed Staphylococcus aureus was 75% and for 6 kGy exposure to electron beam was 25%.

  9. The demise of multidrug-resistant HIV-1: the national time trend in Portugal

    Science.gov (United States)

    Vercauteren, Jurgen; Theys, Kristof; Carvalho, Ana Patricia; Valadas, Emília; Duque, Luis Miguel; Teófilo, Eugénio; Faria, Telo; Faria, Domitília; Vera, José; Águas, Maria João; Peres, Susana; Mansinho, Kamal; Vandamme, Anne-Mieke; Camacho, Ricardo Jorge; Mansinho, Kamal; Cláudia Miranda, Ana; Aldir, Isabel; Ventura, Fernando; Nina, Jaime; Borges, Fernando; Valadas, Emília; Doroana, Manuela; Antunes, Francisco; João Aleixo, Maria; João Águas, Maria; Botas, Júlio; Branco, Teresa; Vera, José; Vaz Pinto, Inês; Poças, José; Sá, Joana; Duque, Luis; Diniz, António; Mineiro, Ana; Gomes, Flora; Santos, Carlos; Faria, Domitília; Fonseca, Paula; Proença, Paula; Tavares, Luís; Guerreiro, Cristina; Narciso, Jorge; Faria, Telo; Teófilo, Eugénio; Pinheiro, Sofia; Germano, Isabel; Caixas, Umbelina; Faria, Nancy; Paula Reis, Ana; Bentes Jesus, Margarida; Amaro, Graça; Roxo, Fausto; Abreu, Ricardo; Neves, Isabel

    2013-01-01

    Objectives Despite a decreasing mortality and morbidity in treated HIV-1 patients, highly active antiretroviral treatment (HAART) can still fail due to the development of drug resistance. Especially, multidrug-resistant viruses pose a threat to efficient therapy. We studied the changing prevalence of multidrug resistance (MDR) over time in a cohort of HIV-1-infected patients in Portugal. Patients and methods We used data of 8065 HIV-1-infected patients followed from July 2001 up to April 2012 in 22 hospitals located in Portugal. MDR at a specific date of sampling was defined as no more than one fully active drug (excluding integrase and entry inhibitors) at that time authorized by the Portuguese National Authority of Medicines and Health Products (INFARMED), as interpreted with the Rega algorithm version 8.0.2. A generalized linear mixed model was used to study the time trend of the prevalence of MDR. Results We observed a statistically significant decrease in the prevalence of MDR over the last decade, from 6.9% (95% CI: 5.7–8.4) in 2001–03, 6.0% (95% CI: 4.9–7.2) in 2003–05, 3.7% (95% CI: 2.8–4.8) in 2005–07 and 1.6% (95% CI: 1.1–2.2) in 2007–09 down to 0.6% (95% CI: 0.3–0.9) in 2009–12 [OR = 0.80 (95% CI: 0.75–0.86); P < 0.001]. In July 2011 the last new case of MDR was seen. Conclusions The prevalence of multidrug-resistant HIV-1 is decreasing over time in Portugal, reflecting the increasing efficiency of HAART and the availability of new drugs. Therefore, in designing a new drug, safety and practical aspects, e.g. less toxicity and ease of use, may need more attention than focusing mainly on efficacy against resistant strains. PMID:23228933

  10. Decellularized human amniotic membrane: more is needed for an efficient dressing for protection of burns against antibiotic-resistant bacteria isolated from burn patients.

    Science.gov (United States)

    Gholipourmalekabadi, M; Bandehpour, M; Mozafari, M; Hashemi, A; Ghanbarian, H; Sameni, M; Salimi, M; Gholami, M; Samadikuchaksaraei, A

    2015-11-01

    Human amniotic membranes (HAMs) have attracted the attention of burn surgeons for decades due to favorable properties such as their antibacterial activity and promising support of cell proliferation. On the other hand, as a major implication in the health of burn patients, the prevalence of bacteria resistant to multiple antibiotics is increasing due to overuse of antibiotics. The aim of this study was to investigate whether HAMs (both fresh and acellular) are an effective antibacterial agent against antibiotic-resistant bacteria isolated from burn patients. Therefore, a HAM was decellularized and tested for its antibacterial activity. Decellularization of the tissue was confirmed by hematoxylin and eosin (H&E) and 4,6-diamidino-2-phenylindole (DAPI) staining. In addition, the cyto-biocompatibility of the acellular HAM was proven by the cell viability test (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide, MTT) and scanning electron microscopy (SEM). The resistant bacteria were isolated from burns, identified, and tested for their susceptibility to antibiotics using both the antibiogram and polymerase chain reaction (PCR) techniques. Among the isolated bacteria, three blaIMP gene-positive Pseudomonas aeruginosa strains were chosen for their high resistance to the tested antibiotics. The antibacterial activity of the HAM was also tested for Klebsiella pneumoniae (American Type Culture Collection (ATCC) 700603) as a resistant ATCC bacterium; Staphylococcus aureus (mecA positive); and three standard strains of ATCC bacteria including Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27833), and S. aureus (ATCC 25923). Antibacterial assay revealed that only the latter three bacteria were susceptible to the HAM. All the data obtained from this study suggest that an alternative strategy is required to complement HAM grafting in order to fully protect burns from nosocomial infections. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

  11. The effect of Nanocrystalline cellulose/Gum Arabic conjugates in crosslinked membrane for antibacterial, chlorine resistance and boron removal performance.

    Science.gov (United States)

    Asim, Saba; Wasim, Maria; Sabir, Aneela; Shafiq, Muhammad; Andlib, Huma; Khuram, Sania; Ahmad, Adnan; Jamil, Tahir

    2018-02-05

    In this work, we developed hybrid membranes integrated with Nanocrystalline cellulose (NCC)/Gum Arabic (GuA) conjugates using crosslinked Poly (vinyl alcohol) (PVA) as a matrix phase with the addition of PEO-PPO-PEO block copolymer that insured pore formation. At first, the NCC was prepared from microcrystalline cellulose via acid hydrolysis process. The performance property of hybrid NCC/GuA was measured using boron removal. The results showed that the rejection capability enhanced as compared to the control membranes, especially at 0.1wt% of NCC the selectivity is up to 92.4% with the flux rate of 21.3L/m 2 .h. Moreover, the GuA in NCC/GuA conjugate significantly enhances the antibacterial activity by hindering the bacterial attachment to the surface as both of them carry the negative charge. Also by providing the active sites responsible for hydrogen bonding thus enhancing the hydrophilic character resulted in increased permeation flux rate. Therefore, the NCC/GuA conjugated membranes have great potentials for boron removal. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Contribution of aquaporin 9 and multidrug resistance-associated protein 2 to differential sensitivity to arsenite between primary cultured chorion and amnion cells prepared from human fetal membranes

    International Nuclear Information System (INIS)

    Yoshino, Yuta; Yuan, Bo; Kaise, Toshikazu; Takeichi, Makoto; Tanaka, Sachiko; Hirano, Toshihiko; Kroetz, Deanna L.; Toyoda, Hiroo

    2011-01-01

    Arsenic trioxide (arsenite, As III ) has shown a remarkable clinical efficacy, whereas its side effects are still a serious concern. Therefore, it is critical to understand the effects of As III on human-derived normal cells for revealing the mechanisms underlying these side effects. We examined the effects of As III on primary cultured chorion (C) and amnion (A) cells prepared from human fetal membranes. A significant dose-dependent As III -mediated cytotoxicity was observed in the C-cells accompanied with an increase of lactate dehydrogenase (LDH) release. Higher concentrations of As III were required for the A-cells to show cytotoxicity and LDH release, suggesting that the C-cells were more sensitive to As III than the A-cells. The expression levels of aquaporin 9 (AQP9) were approximately 2 times higher in the C-cells than those in the A-cells. Both intracellular arsenic accumulation and its cytotoxicity in the C-cells were significantly abrogated by sorbitol, a competitive AQP9 inhibitor, in a dose-dependent manner. The protein expression levels of multidrug resistance-associated protein (MRP) 2 were downregulated by As III in the C-cells, but not in the A-cells. No significant differences in the expression levels of MRP1 were observed between C- and A-cells. The protein expression of P-glycoprotein (P-gp) was hardly detected in both cells, although a detectable amount of its mRNA was observed. Cyclosporine A, a broad-spectrum inhibitor for ABC transporters, and MK571, a MRP inhibitor, but not PGP-4008, a P-gp specific inhibitor, potently sensitized both cells to As III -mediated cytotoxicity. These results suggest that AQP9 and MRP2 are involved in controlling arsenic accumulation in these normal cells, which then contribute to differential sensitivity to As III cytotoxicity between these cells. -- Highlights: ► Examination of effect of As III on primary cultured chorion (C) and amnion (A) cells. ► Dose-dependent As III -mediated cytotoxicity in C

  13. Contribution of aquaporin 9 and multidrug resistance-associated protein 2 to differential sensitivity to arsenite between primary cultured chorion and amnion cells prepared from human fetal membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, Yuta [Department of Clinical Molecular Genetics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392 (Japan); Yuan, Bo, E-mail: yuanbo@toyaku.ac.jp [Department of Clinical Molecular Genetics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392 (Japan); Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH584E Box 2911 San Francisco, CA 94158-2911 (United States); Kaise, Toshikazu [Laboratory of Environmental Chemodynamics, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392 (Japan); Takeichi, Makoto [Yoneyama Maternity Hospital, 2-12 Shin-machi, Hachioji, Tokyo 192-0065 (Japan); Tanaka, Sachiko; Hirano, Toshihiko [Department of Clinical Pharmacology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392 (Japan); Kroetz, Deanna L. [Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH584E Box 2911 San Francisco, CA 94158-2911 (United States); Toyoda, Hiroo [Department of Clinical Molecular Genetics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392 (Japan)

    2011-12-15

    Arsenic trioxide (arsenite, As{sup III}) has shown a remarkable clinical efficacy, whereas its side effects are still a serious concern. Therefore, it is critical to understand the effects of As{sup III} on human-derived normal cells for revealing the mechanisms underlying these side effects. We examined the effects of As{sup III} on primary cultured chorion (C) and amnion (A) cells prepared from human fetal membranes. A significant dose-dependent As{sup III}-mediated cytotoxicity was observed in the C-cells accompanied with an increase of lactate dehydrogenase (LDH) release. Higher concentrations of As{sup III} were required for the A-cells to show cytotoxicity and LDH release, suggesting that the C-cells were more sensitive to As{sup III} than the A-cells. The expression levels of aquaporin 9 (AQP9) were approximately 2 times higher in the C-cells than those in the A-cells. Both intracellular arsenic accumulation and its cytotoxicity in the C-cells were significantly abrogated by sorbitol, a competitive AQP9 inhibitor, in a dose-dependent manner. The protein expression levels of multidrug resistance-associated protein (MRP) 2 were downregulated by As{sup III} in the C-cells, but not in the A-cells. No significant differences in the expression levels of MRP1 were observed between C- and A-cells. The protein expression of P-glycoprotein (P-gp) was hardly detected in both cells, although a detectable amount of its mRNA was observed. Cyclosporine A, a broad-spectrum inhibitor for ABC transporters, and MK571, a MRP inhibitor, but not PGP-4008, a P-gp specific inhibitor, potently sensitized both cells to As{sup III}-mediated cytotoxicity. These results suggest that AQP9 and MRP2 are involved in controlling arsenic accumulation in these normal cells, which then contribute to differential sensitivity to As{sup III} cytotoxicity between these cells. -- Highlights: Black-Right-Pointing-Pointer Examination of effect of As{sup III} on primary cultured chorion (C) and amnion

  14. Effects of supplement timing and resistance exercise on skeletal muscle hypertrophy.

    Science.gov (United States)

    Cribb, Paul J; Hayes, Alan

    2006-11-01

    Some studies report greater muscle hypertrophy during resistance exercise (RE) training from supplement timing (i.e., the strategic consumption of protein and carbohydrate before and/or after each workout). However, no studies have examined whether this strategy provides greater muscle hypertrophy or strength development compared with supplementation at other times during the day. The purpose of this study was to examine the effects of supplement timing compared with supplementation in the hours not close to the workout on muscle-fiber hypertrophy, strength, and body composition during a 10-wk RE program. In a single-blind, randomized protocol, resistance-trained males were matched for strength and placed into one of two groups; the PRE-POST group consumed a supplement (1 g x kg(-1) body weight) containing protein/creatine/glucose immediately before and after RE. The MOR-EVE group consumed the same dose of the same supplement in the morning and late evening. All assessments were completed the week before and after 10 wk of structured, supervised RE training. Assessments included strength (1RM, three exercises), body composition (DEXA), and vastus lateralis muscle biopsies for determination of muscle fiber type (I, IIa, IIx), cross-sectional area (CSA), contractile protein, creatine (Cr), and glycogen content. PRE-POST demonstrated a greater (P supplementation also resulted in higher muscle Cr and glycogen values after the training program (P Supplement timing represents a simple but effective strategy that enhances the adaptations desired from RE-training.

  15. The influence of superoxide dimutase and some other radical scavengers on X-ray resistance, life span and membrane integrity of Sacharomyces cerevisiae

    International Nuclear Information System (INIS)

    Hartwig, V.

    1988-01-01

    Evaluations of various strains of yeast showed these to differ widely in the activities of superoxide dimutase and catalase, X-ray sensitivity, reproductive capacity and malondialdehyde concentration. Higher SOD activities in reponse to increases in oxygen production under extreme physiological conditions were observed for the cells of a haploid strain and just as well seen in those of a diploid strain. There were findings pointing to mutually 'compensatory' effects in respect of the contents of CAT and thiol. When intracellular radical scavengers were 'overstrained' by exposure to high X-ray doses, untoward effects on membrane integrity could be detected after irradiation. The use of the SOD-specific inhibitor DDC led to a reduction of both X-ray resistance and life span as a result of SOD-inhibition. Exogenous SOD was seen to reduce the mean life span. Cu 2+ and Mn 2+ were found to have a dual action in that they not only increased the resistance to X-rays through an augmentation of SOD activity but also had an immediate beneficial effect on radioresistance. Exogenous H202 led to an increase in the cellular CAT contents and an enhancement of X-ray resistance. (orig./MG) [de

  16. Cholesterol Induced Changes in the Characteristics of the Time Series From Planar Lipid Bilayer Membrane during Electroporation

    International Nuclear Information System (INIS)

    Kotulska, M.; Koronkiewicz, S.; Kalinowski, S.

    2002-01-01

    The electroporation can be used as a non-toxic method for introducing exogenous macromolecules, especially DNA and drugs, into various types of cells. Research in to new therapeutic methods based on Long Duration Electroporation (LDE) is of special interest. A new current-clamp method makes possible the electroporation of very long duration with no damage to bio-membranes. In this paper we compare responses of lipid planar bilayer membranes at physiological concentration of KCl, with lipid membranes formed at higher ionic strength, and membranes containing cholesterol. A longer lifespan of the membranes with cholesterol and membranes with increased ionic strength could be observed. Sensitivity of the power spectrum response to the presence of cholesterol, ionic strength, current intensity, and membrane ageing was examined. The membrane memory was analyzed by means of autocorrelation function and rescaled range analysis. We showed that the memory of the system decreases for higher current intensities and this relation is pronounced better at higher ionic strength. At low current intensities all membranes showed slightly persistent type of noise behavior with crossover to Brownian type of noise for higher current value. The transition w as much faster for higher ionic strength, where the next transition to anti-persistent response was observed for relatively low currents. Very interesting results were obtained from power spectrum analysis. At low current intensity, all membranes exhibited 1/f noise, which disappeared for higher currents, maintaining f β type with rising value of β. Membranes formed at lower ionic strength and with cholesterol showed a pronounced tendency to lose flicker noise while ageing, also with rising β value. (author)

  17. Resistance of human glioma to adriamycin in vitro: the role of membrane transport and its circumvention with verapamil.

    Science.gov (United States)

    Merry, S; Fetherston, C A; Kaye, S B; Freshney, R I; Plumb, J A

    1986-01-01

    We have investigated the mechanism of resistance to adriamycin (ADR) of 3 human glioma cell lines in culture. The cell lines had different inherent sensitivities to ADR. Verapamil increased the ADR sensitivities of the 2 most resistant cell lines (G-UVW and G-CCM) by up to 5-fold. This effect was not seen in a sensitive cell line (G-MCF). Although the accumulation of ADR in the 3 cell lines was not related to inherent sensitivity, energy deprivation or the addition of verapamil produced an increase (up to 46%) in net uptake for both G-UVW and G-CCM, but not for G-MCF. For G-UVW the ADR efflux data were consistent with an energy-dependent ADR efflux mechanism which could be inhibited by verapamil. A similar mechanism was not found for G-CCM. In this cell line verapamil may act by increasing intracellular ADR binding. These data indicate that, while inherent resistance to ADR may be multifactorial, one possible mechanism of resistance in human glioma may involve changes in drug accumulation and/or binding as has been seen in animals models. A potential clinical role for verapamil in overcoming drug resistance in human solid tumours is also indicated.

  18. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-02-01

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

  19. Effects of etching time on the bottom surface morphology of ultrathin porous alumina membranes for use as masks

    Science.gov (United States)

    Yang, Sun A.; Choi, Yong Chan; Bu, Sang Don

    2012-11-01

    We investigated the effect of etching time on the bottom surface morphologies of ultrathin porous alumina membranes (UT-PAMs) anodized in oxalic and phosphoric acid. The morphology of the bottom surface clearly changed and a unique surface undulation was observed during the etching process. Such an undulation regarding the bottom surface is attributed to the different etching rates between the dome-shaped barrier layer and the hexagonal cell walls. The results suggest that the bottom morphology of UT-PAMs formed after the barrier layer is opened significantly affects the contact area of the bottom side with the substrate. During the initial stage of the opening process for the barrier layer, the porous section will contact the substrate rather than the walls. However, as the etching time increases, the height of the porous section becomes considerably lower than that of the walls, which means that the walls will contact the substrate with a gap between the pores and the substrate. Based on our experimental results, we propose a possible schematic diagram describing the effects of UT-PAMs with differently-shaped bottom surfaces on the shapes of fabricated nanodots when the UT-PAMs are used as masks.

  20. The Antibiotic Resistance Arrow of Time: Efflux Pump Induction Is a General First Step in the Evolution of Mycobacterial Drug Resistance

    OpenAIRE

    Schmalstieg, Aurelia M.; Srivastava, Shashikant; Belkaya, Serkan; Deshpande, Devyani; Meek, Claudia; Leff, Richard; van Oers, Nicolai S. C.; Gumbo, Tawanda

    2012-01-01

    We hypothesize that low-level efflux pump expression is the first step in the development of high-level drug resistance in mycobacteria. We performed 28-day azithromycin dose-effect and dose-scheduling studies in our hollow-fiber model of disseminated Mycobacterium avium-M. intracellulare complex. Both microbial kill and resistance emergence were most closely linked to the within-macrophage area under the concentration-time curve (AUC)/MIC ratio. Quantitative PCR revealed that subtherapeutic ...

  1. Regulatory Protein OmpR Influences the Serum Resistance of Yersinia enterocolitica O:9 by Modifying the Structure of the Outer Membrane

    Science.gov (United States)

    Skorek, Karolina; Raczkowska, Adrianna; Dudek, Bartłomiej; Miętka, Katarzyna; Guz-Regner, Katarzyna; Pawlak, Aleksandra; Klausa, Elżbieta; Bugla-Płoskońska, Gabriela; Brzostek, Katarzyna

    2013-01-01

    The EnvZ/OmpR two-component system constitutes a regulatory pathway involved in bacterial adaptive responses to environmental cues. Our previous findings indicated that the OmpR regulator in Yersinia enterocolitica O:9 positively regulates the expression of FlhDC, the master flagellar activator, which influences adhesion/invasion properties and biofilm formation. Here we show that a strain lacking OmpR grown at 37°C exhibits extremely high resistance to the bactericidal activity of normal human serum (NHS) compared with the wild-type strain. Analysis of OMP expression in the ompR mutant revealed that OmpR reciprocally regulates Ail and OmpX, two homologous OMPs of Y. enterocolitica, without causing significant changes in the level of YadA, the major serum resistance factor. Analysis of mutants in individual genes belonging to the OmpR regulon (ail, ompX, ompC and flhDC) and strains lacking plasmid pYV, expressing YadA, demonstrated the contribution of the respective proteins to serum resistance. We show that Ail and OmpC act in an opposite way to the OmpX protein to confer serum resistance to the wild-type strain, but are not responsible for the high resistance of the ompR mutant. The serum resistance phenotype of ompR seems to be multifactorial and mainly attributable to alterations that potentiate the function of YadA. Our results indicate that a decreased level of FlhDC in the ompR mutant cells is partly responsible for the serum resistance and this effect can be suppressed by overexpression of flhDC in trans. The observation that the loss of FlhDC enhances the survival of wild-type cells in NHS supports the involvement of FlhDC regulator in this phenotype. In addition, the ompR mutant exhibited a lower level of LPS, but this was not correlated with changes in the level of FlhDC. We propose that OmpR might alter the susceptibility of Y. enterocolitica O:9 to complement-mediated killing through remodeling of the outer membrane. PMID:24260242

  2. Regulatory protein OmpR influences the serum resistance of Yersinia enterocolitica O:9 by modifying the structure of the outer membrane.

    Directory of Open Access Journals (Sweden)

    Karolina Skorek

    Full Text Available The EnvZ/OmpR two-component system constitutes a regulatory pathway involved in bacterial adaptive responses to environmental cues. Our previous findings indicated that the OmpR regulator in Yersinia enterocolitica O:9 positively regulates the expression of FlhDC, the master flagellar activator, which influences adhesion/invasion properties and biofilm formation. Here we show that a strain lacking OmpR grown at 37°C exhibits extremely high resistance to the bactericidal activity of normal human serum (NHS compared with the wild-type strain. Analysis of OMP expression in the ompR mutant revealed that OmpR reciprocally regulates Ail and OmpX, two homologous OMPs of Y. enterocolitica, without causing significant changes in the level of YadA, the major serum resistance factor. Analysis of mutants in individual genes belonging to the OmpR regulon (ail, ompX, ompC and flhDC and strains lacking plasmid pYV, expressing YadA, demonstrated the contribution of the respective proteins to serum resistance. We show that Ail and OmpC act in an opposite way to the OmpX protein to confer serum resistance to the wild-type strain, but are not responsible for the high resistance of the ompR mutant. The serum resistance phenotype of ompR seems to be multifactorial and mainly attributable to alterations that potentiate the function of YadA. Our results indicate that a decreased level of FlhDC in the ompR mutant cells is partly responsible for the serum resistance and this effect can be suppressed by overexpression of flhDC in trans. The observation that the loss of FlhDC enhances the survival of wild-type cells in NHS supports the involvement of FlhDC regulator in this phenotype. In addition, the ompR mutant exhibited a lower level of LPS, but this was not correlated with changes in the level of FlhDC. We propose that OmpR might alter the susceptibility of Y. enterocolitica O:9 to complement-mediated killing through remodeling of the outer membrane.

  3. The association between n-3 fatty acids in erythrocyte membranes and insulin resistance: The Inuit Health in Transition Study

    DEFF Research Database (Denmark)

    Thorseng, Trine; Witte, Daniel R; Vistisen, Dorte

    2009-01-01

    Objectives. To examine the association between the content of n-3 fatty acids and insulin resistance in an Inuit population. Study design. The Inuit Health in Transition Study was carried out between 2003 and 2007 in Greenland as a cross-sectional study. Our preliminary results are based...... adjusted for age, gender, BMI and ethnicity, the association remained statistically significant for C20:5 n-3 (EPA), C22:3 n-3 and C18:3 n-3 cis. Conclusions. Our findings suggest that some types of n-3 fatty acids may have a protective effect against insulin resistance. The role of potential confounders...

  4. Application of neural network for real-time measurement of electrical resistivity in cold crucible

    Science.gov (United States)

    Votava, Pavel; Poznyak, Igor

    2017-08-01

    The article describes use of an Induction furnace with cold crucible as a tool for real-time measurement of a melted material electrical resistivity. The measurement is based on an inverse problem solution of a 2D mathematical model, possibly implementable in a microcontroller or a FPGA in a form of a neural network. The 2D mathematical model results has been provided as a training set for the neural network. At the end, the implementation results are discussed together with uncertainty of measurement, which is done by the neural network implementation itself.

  5. Tracking snowmelt in the subsurface: time-lapse electrical resistivity imaging on an alpine hill slope.

    Science.gov (United States)

    Thayer, D.; Parsekian, A.; Hyde, K.; Beverly, D.; Speckman, H. N.; Ewers, B. E.

    2015-12-01

    In the mountain West region the winter snowpack provides more than 70% of our annual water supply. Modeling and predicting the timing and magnitude of snowmelt-driven water yield is difficult due to the complexities of hydrologic systems that move meltwater from snow to rivers. Particular challenges are understanding the temporal and spatial domain of subsurface hydraulic processes at relevant scales, which range from points to catchments. Subsurface characterization often requires borehole instrumentation, which is expensive and extremely difficult to install in remote, rugged terrain. Advancements in non-invasive geophysical methods allow us to monitor changes in geophysical parameters over time and infer changes in hydraulic processes. In the No-Name experimental catchment in the Medicine Bow National Forest in Wyoming, we are conducting a multi-season, time-lapse electrical resistivity imaging survey on a sub-alpine hill slope. This south-facing, partially forested slope ranges from 5 degrees to 35 degrees in steepness and consists of a soil mantle covering buried glacial talus deposits of unknown depth. A permanent grid of down-slope and cross-slope electrode arrays is monitored up to four times a day. The arrays span the entire vertical distance of the slope, from an exposed bedrock ridge to a seasonal drainage below, and cover treed and non-treed areas. Geophysical measurements are augmented by temperature and moisture time-series instrumented below the surface in a contiguous 3 meter borehole. A time-series of multiple resistivity models each day from May to July shows the changing distribution of subsurface moisture during a seasonal drying sequence punctuated by isolated rain events. Spatial patterns of changing moisture indicate that soil and gravel in the top two meters drain into a saturated layer parallel to the slope which overlies less saturated material. These results suggest that water from snowmelt and rain events tends to move down-slope beneath

  6. Effects of resistance exercise timing on sleep architecture and nocturnal blood pressure.

    Science.gov (United States)

    Alley, Jessica R; Mazzochi, John W; Smith, Caroline J; Morris, David M; Collier, Scott R

    2015-05-01

    Short sleep duration and poor quality of sleep have been associated with health risks including cardiovascular disease, diabetes, and obesity. Prior research has suggested that regular aerobic exercise improves the quality of sleep; however, less is known regarding resistance exercise (RE) and how RE may affect sleep architecture. The purpose of this study was to investigate the acute effects of timing of RE on sleep architecture and nocturnal blood pressure. College-aged subjects engaged in 5 laboratory visits. Visits 1 (C) and 2 provided a non-RE control day and established the 10-repetition maximum on each of 9 RE machines, respectively. During visits 3-5, the subjects reported at 0700 hours (7A), 1300 hours (1P), and 1900 hours (7P) in a randomized order to perform 30 minutes of RE. Ambulatory blood pressure and sleep-monitoring devices were worn during sleep after C, 7A, 1P, and 7P. Time to fall asleep was significantly different between RE conditions 7A and 1P and between 7A and 7P. All exercise conditions exhibited significantly fewer times woken than the non-RE control day, with 7P resulting in significantly less time awake after initially falling asleep as compared with C. Although timing of RE does not seem to statistically impact sleep stages or nocturnal blood pressure, these data indicate that engaging in RE at any time of the day may improve quality of sleep as compared with no RE. Resistance exercise may offer additional benefits regarding the ability to fall asleep and stay asleep to populations with osteoporosis, sarcopenia, anxiety, or depression.

  7. The antibiotic resistance arrow of time: efflux pump induction is a general first step in the evolution of mycobacterial drug resistance.

    Science.gov (United States)

    Schmalstieg, Aurelia M; Srivastava, Shashikant; Belkaya, Serkan; Deshpande, Devyani; Meek, Claudia; Leff, Richard; van Oers, Nicolai S C; Gumbo, Tawanda

    2012-09-01

    We hypothesize that low-level efflux pump expression is the first step in the development of high-level drug resistance in mycobacteria. We performed 28-day azithromycin dose-effect and dose-scheduling studies in our hollow-fiber model of disseminated Mycobacterium avium-M. intracellulare complex. Both microbial kill and resistance emergence were most closely linked to the within-macrophage area under the concentration-time curve (AUC)/MIC ratio. Quantitative PCR revealed that subtherapeutic azithromycin exposures over 3 days led to a 56-fold increase in expression of MAV_3306, which encodes a putative ABC transporter, and MAV_1406, which encodes a putative major facilitator superfamily pump, in M. avium. By day 7, a subpopulation of M. avium with low-level resistance was encountered and exhibited the classic inverted U curve versus AUC/MIC ratios. The resistance was abolished by an efflux pump inhibitor. While the maximal microbial kill started to decrease after day 7, a population with high-level azithromycin resistance appeared at day 28. This resistance could not be reversed by efflux pump inhibitors. Orthologs of pumps encoded by MAV_3306 and MAV_1406 were identified in Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium marinum, Mycobacterium abscessus, and Mycobacterium ulcerans. All had highly conserved protein secondary structures. We propose that induction of several efflux pumps is the first step in a general pathway to drug resistance that eventually leads to high-level chromosomal-mutation-related resistance in mycobacteria as ordered events in an "antibiotic resistance arrow of time."

  8. 77 FR 25405 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Science.gov (United States)

    2012-04-30

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-580-816] Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time Limit for the Preliminary Results of... antidumping duty order on corrosion-resistant carbon steel flat products from the Republic of Korea, covering...

  9. 75 FR 18153 - Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea: Extension of Time...

    Science.gov (United States)

    2010-04-09

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea: Extension of Time Limit for Preliminary Results of... countervailing duty order on corrosion-resistant carbon steel flat products (CORE) from Korea. See Countervailing...

  10. 75 FR 25841 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Science.gov (United States)

    2010-05-10

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-580-816] Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time Limits for the Preliminary Results of... antidumping duty order on corrosion-resistant carbon steel flat products from the Republic of Korea, covering...

  11. 76 FR 21332 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Science.gov (United States)

    2011-04-15

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-580-816] Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time Limits for the Preliminary Results of... antidumping duty order on corrosion-resistant carbon steel flat products from the Republic of Korea, covering...

  12. 76 FR 20954 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Science.gov (United States)

    2011-04-14

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time Limit for Preliminary Results of... Register the countervailing duty order on corrosion-resistant carbon steel flat products (CORE) from Korea...

  13. 77 FR 16810 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Science.gov (United States)

    2012-03-22

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-580-818] Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time Limit for Preliminary Results of... Register the countervailing duty order on corrosion-resistant carbon steel flat products (CORE) from Korea...

  14. Effect of manure application rate and rainfall timing on the leaching of antibiotic-resistant bacteria and their associated genes.

    Science.gov (United States)

    In this study we investigate the effect of application rate and timing of liquid swine slurry on leaching of antibiotic-resistant bacteria (ARB) and their antibiotic-resistance genes (ARG) through soil columns. Swine slurry was added to laboratory soil columns at rates of 5,000 or 30,000 gallons acr...

  15. 77 FR 25141 - Corrosion-Resistant Carbon Steel Flat Products From Germany and South Korea: Extension of Time...

    Science.gov (United States)

    2012-04-27

    ...-Resistant Carbon Steel Flat Products From Germany and South Korea: Extension of Time Limits for Preliminary...) orders on corrosion-resistant carbon steel flat products (CORE) from Germany and South Korea (Korea... from Germany and South Korea: Adequacy Redetermination Memorandum,'' (April 20, 2012). The preliminary...

  16. The breast cancer resistance protein transporter ABCG2 is expressed in the human kidney proximal tubule apical membrane.

    NARCIS (Netherlands)

    Huls, M.; Brown, C.D.; Windass, A.S.; Sayer, R.; Heuvel, J.J.M.W. van den; Heemskerk, S.; Russel, F.G.M.; Masereeuw, R.

    2008-01-01

    The Breast Cancer Resistance Protein (BCRP/ABCG2) is a transporter restricting absorption and enhancing excretion of many compounds including anticancer drugs. This transporter is highly expressed in many tissues; however, in human kidney, only the mRNA was found in contrast to the mouse kidney,

  17. MexCD-OprJ multidrug efflux system of Pseudomonas aeruginosa: involvement in chlorhexidine resistance and induction by membrane-damaging agents dependent upon the AlgU stress response sigma factor.

    Science.gov (United States)

    Fraud, Sebastien; Campigotto, Aaron J; Chen, Zhilin; Poole, Keith

    2008-12-01

    The biocide chlorhexidine (CHX) as well as additional membrane-active agents were shown to induce expression of the mexCD-oprJ multidrug efflux operon, dependent upon the AlgU stress response sigma factor. Hyperexpression of this efflux system in nfxB mutants was also substantially AlgU dependent. CHX resistance correlated with efflux gene expression in various mutants, consistent with MexCD-OprJ being a determinant of CHX resistance.

  18. 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.

  19. Detection of graft detachments immediately following Descemet membrane endothelial keratoplasty (DMEK) comparing time domain and spectral domain OCT.

    Science.gov (United States)

    Siebelmann, Sebastian; Gehlsen, Uta; Le Blanc, Carolin; Stanzel, Tisha Prabriputaloong; Cursiefen, Claus; Steven, Philipp

    2016-12-01

    Correct early graft attachment is believed to be crucial for final visual outcome after Descemet membrane endothelial keratoplasty (DMEK). Nonetheless, it is not yet known which imaging technique gives superior results for examining early postoperative graft adherence status. We compared imaging data taken with two different OCT devices to examine the development of graft adherence immediately after DMEK and to determine the superior device in terms of visualization of graft adherence. Ten consecutive patients (1 man/9 women) were examined three times postoperatively within the first 7 h after DMEK surgery using spectral domain OCT (SD-OCT) and time domain OCT (TD-OCT), as prospective case series and retrospective image data analyses. The parameters analyzed were localization and number, visibility and size of graft detachments. TD-OCT was able to detect a greater number of graft detachments after DMEK; however, SD-OCT provided better resolution of minor detachments. Graft detachments varied in position and degree at different time points immediately after surgery. All patients had some graft detachment within the first 7 h after DMEK surgery. TD-OCT enabled better overall analysis of graft detachments, even in the periphery, whereas SD-OCT allowed for the detection of even minor detachments, which suggests that a combination of the two techniques is optimal. Our results indicate that dynamic processes affecting the DMEK graft immediately after transplantation are responsible for changes in the attachment of donor tissue at an early postoperative stage. Modulation of early graft attachment may improve the final graft attachment.

  20. Direct estimation of the permeation of topical excipients through artificial membranes and human skin with non-invasive Terahertz time-domain techniques.

    Science.gov (United States)

    Lopez-Dominguez, Victor; Boix-Montañes, Antoni; Redo-Sanchez, Albert; Tejada-Palacios, Javier

    2016-07-01

    Drug permeation through skin, or a synthetic membrane, from locally acting pharmaceutical products can be influenced by the permeation behaviour of pharmaceutical excipients. Terahertz time-domain technology is investigated as a non-invasive method for a direct and accurate measurement of excipients permeation through synthetic membranes or human skin. A series of in-vitro release and skin permeation experiments of liquid excipients (e.g. propylene glycol and polyethylene glycol 400) has been conducted with vertical diffusion cells. The permeation profiles of excipients through different synthetic membranes or skin were obtained using Terahertz pulses providing a direct measurement. Corresponding permeation flux and permeability coefficient values were calculated based on temporal changes of the terahertz pulses. The influence of different experimental conditions, such as the polarity of the membrane and the viscosity of the permeant, was assessed in release experiments. Specific transmembrane flux values of those excipients were directly calculated with statistical differences between cases. Finally, an attempt to estimate the skin permeation of propylene glycol with this technique was also achieved. All these permeation results were likely comparable to those obtained by other authors with usual analytical techniques. Terahertz time-domain technology is shown to be a suitable technique for an accurate and non-destructive measurement of the permeation of liquid substances through different synthetic membranes or even human skin. © 2016 Royal Pharmaceutical Society.

  1. The association between n-3 fatty acids in erythrocyte membranes and insulin resistance: The Inuit Health in Transition Study

    DEFF Research Database (Denmark)

    Thorseng, Trine; Witte, Daniel R; Vistisen, Dorte

    2009-01-01

    and ethnicity were answered. Insulin resistance was estimated using the HOMA-IR index based on fastingglucose and fasting-insulin. Results. We found an inverse association between C20:5 n-3 (EPA), C22:3 n-3, the n-3/n-6 ratio and HOMA-IR and a positive association between C18:3 n-3 cis and HOMA-IR. When...

  2. Outer Membrane Protein D Gene in Clinical Isolates of Pseudomonas Aeruginosa and its Role in Antibiotic Resistance

    OpenAIRE

    Neda Motaghi; Sohrab Najafipour

    2016-01-01

    Background & Objectives: Pseudomonas aeruginosa is a common cause of nosocomial infection. OprD protein is a specific protein regulating the uptake of carbapenem antibiotic. Loss of OprD is the main mechanism of Pseudomonas Aeruginosa resistance to carbapenem. In this study, the presence of OprD gene is investigated in isolated Pseudomonas Aeruginosa in burn patients of Ghotboddin hospital in Shiraz. Material & Methods: 66 Pseudomonas Aeruginosa were isolated from wound specimens of 250 b...

  3. Outer Membrane Protein D Gene in Clinical Isolates of Pseudomonas Aeruginosa and its Role in Antibiotic Resistance

    Directory of Open Access Journals (Sweden)

    Neda Motaghi

    2016-03-01

    Full Text Available Background & Objectives: Pseudomonas aeruginosa is a common cause of nosocomial infection. OprD protein is a specific protein regulating the uptake of carbapenem antibiotic. Loss of OprD is the main mechanism of Pseudomonas Aeruginosa resistance to carbapenem. In this study, the presence of OprD gene is investigated in isolated Pseudomonas Aeruginosa in burn patients of Ghotboddin hospital in Shiraz. Material & Methods: 66 Pseudomonas Aeruginosa were isolated from wound specimens of 250 burn patients. Strain characteristics were confirmed by biochemical tests. Antibiogram was done via disc diffusion method. Finally, OprD gene was investigated by PCR. Results: Isolated Pseudomonas Aeruginosa showed more sensitivity to chloramphenicol and colicitin and more resistance  to ciprofloxacin, gentamycin, cefotaxim, ceftazidin, imipenem, meropenem, and erythromycin. 61 percent of isolates were positive for OprD gene by PCR. Conclusion: The findings of this study revealed that Colicitin and chloramphenicol are more effective in treatment of Pseudomonas Aeruginosa infections in burn patients, and deletion and mutation in OprD gene cause bacterium resistance to carbapenem antibiotic.

  4. Paclitaxel resistance development is associated with biphasic changes in reactive oxygen species, mitochondrial membrane potential and autophagy with elevated energy production capacity in lung cancer cells: A chronological study.

    Science.gov (United States)

    Datta, Satabdi; Choudhury, Diptiman; Das, Amlan; Das Mukherjee, Dipanwita; Das, Nabanita; Roy, Sib Sankar; Chakrabarti, Gopal

    2017-02-01

    Paclitaxel (Tx) is one of the first-line chemotherapeutic drugs used against lung cancer, but acquired resistance to this drug is a major challenge against successful chemotherapy. In this work, we have focused on the chronological changes of various cellular parameters and associated effect on Tx (10 nM) resistance development in A549 cell line. It was observed, at initial stage, the cell death percentage due to drug treatment had increased up to 20 days, and thereafter, it started declining and became completely resistant by 40 days. Expressions of βIII tubulin and drug efflux pumps also increased over the period of resistance development. Changes in cellular autophagy and reactive oxygen species generation showed a biphasic pattern and increased gradually over the course of upto 20 days, thereafter declined gradually; however, their levels remained higher than untreated cells when resistance was acquired. Increase in extracellular acidification rates and oxygen consumption rates was found to be directly correlated with acquisition of resistance. The depolarisation of mitochondrial membrane potential was also biphasic; first, it increased with increase of cell death up to 20 days, thereafter, it gradually decreased to normal level along with resistance development. Increase in activity of catalase, glutathione peroxidase and glutathione content over these periods may attribute in bringing down the reactive oxygen species levels and normalisation of mitochondrial membrane potential in spite of comparatively higher reactive oxygen species production by the Tx-resistant cells.

  5. Solubilization and identification of hen eggshell membrane proteins during different times of chicken embryo development using the proteomic approach.

    Science.gov (United States)

    Kaweewong, Kritsda; Garnjanagoonchorn, Wunwiboon; Jirapakkul, Wannee; Roytrakul, Sittiruk

    2013-04-01

    A fertilized chicken egg is a unit of life. During hatching, transport of nutrients, including calcium, have been reported from the egg components to the developing embryo. Calcium is mobilized from the eggshell with the involvement of Ca(2+)-binding proteins. In addition, other unknown proteins may also play some important roles during embryo developing process. Therefore identification and prediction of biological functions of eggshell membrane (ESM) proteins during chick embryo development was conducted by proteome analysis. Comparison of different lysis solutions indicated that the highest ability to extract ESM proteins could be obtained with 1 % sodium dodecyl sulfate in 5 mM Tris-HCl buffer pH 8.8 containing 0.1 % 2-mercaptoethanol. In this study fertilized Cornish chicken eggs were incubated at 37 °C in humidified incubators for up to 21 days. At selected times (days 1, 9, 15 and 21), samples were taken and the ESMs were carefully separated by hand, washed with distilled water, and air-dried at room temperature. The ESM proteins were then solubilized and analyzed by proteome analysis. Sodium dodecyl sulfate polyacrylamide gel electrophoresis combined with high performance liquid chromatography and mass spectrometry revealed 62 proteins in the ESM; only keratin is known ESM protein, 8 of which are egg white proteins and related while 53 others have not previously been reported. Some differences in the types of proteins and their molecular functions were noted in ESM at different incubation times. One protein which was present only at days 15 and 21 of egg incubation was identified as a calcium binding protein i.e. EGF like repeats and discoidin I like domain 3 (EDIL3 homologous protein).

  6. Analytical solutions for a single vertical drain with time-dependent vacuum combined surcharge preloading in membrane and membraneless systems

    International Nuclear Information System (INIS)

    Geng, X Y; Indraratna, B; Rujikiatkamjorn, C

    2010-01-01

    Vertical drains combined with vacuum pressure and surcharge preloading are widely used to accelerate the consolidation process of soft clay in order to decrease the pore pressure as well as to increase the effective stress. Currently there are two types of vacuum preloading systems commercially available; (a) membrane system with an airtight membrane over the drainage layer and, (b) membraneless system where a vacuum system is connected to individual drain. Their effectiveness varies from site to site depending on the type of soil treated and the characteristics of the drain-vacuum system. This study presents the analytical solutions of vertical drains with vacuum preloading for both membrane and membraneless systems. According to the field and laboratory observations, the vacuum in both of the membraneless and membrane system was assumed to be decreasing along the drain whereas in the membrane system, it was maintained at a constant level. This model was verified by using the measured settlements and excess pore pressures obtained from large-scale laboratory testing and case studies in Australia. The analytical solutions improved the accuracy of predicting the dissipation of pore water pressure and the associated settlement. The effects of the permeability of the sand blanket in a membrane system and the possible loss of vacuum were also discussed.

  7. A cyclopalladated complex interacts with mitochondrial membrane thiol-groups and induces the apoptotic intrinsic pathway in murine and cisplatin-resistant human tumor cells

    International Nuclear Information System (INIS)

    Serrano, Fabiana A; Machado, Joel Jr; Santos, Edson L; Pesquero, João B; Martins, Rafael M; Travassos, Luiz R; Caires, Antonio CF; Rodrigues, Elaine G; Matsuo, Alisson L; Monteforte, Priscila T; Bechara, Alexandre; Smaili, Soraya S; Santana, Débora P; Rodrigues, Tiago; Pereira, Felipe V; Silva, Luis S

    2011-01-01

    Systemic therapy for cancer metastatic lesions is difficult and generally renders a poor clinical response. Structural analogs of cisplatin, the most widely used synthetic metal complexes, show toxic side-effects and tumor cell resistance. Recently, palladium complexes with increased stability are being investigated to circumvent these limitations, and a biphosphinic cyclopalladated complex {Pd 2 [S (-) C 2 , N-dmpa] 2 (μ-dppe)Cl 2 } named C7a efficiently controls the subcutaneous development of B16F10-Nex2 murine melanoma in syngeneic mice. Presently, we investigated the melanoma cell killing mechanism induced by C7a, and extended preclinical studies. B16F10-Nex2 cells were treated in vitro with C7a in the presence/absence of DTT, and several parameters related to apoptosis induction were evaluated. Preclinical studies were performed, and mice were endovenously inoculated with B16F10-Nex2 cells, intraperitoneally treated with C7a, and lung metastatic nodules were counted. The cytotoxic effects and the respiratory metabolism were also determined in human tumor cell lines treated in vitro with C7a. Cyclopalladated complex interacts with thiol groups on the mitochondrial membrane proteins, causes dissipation of the mitochondrial membrane potential, and induces Bax translocation from the cytosol to mitochondria, colocalizing with a mitochondrial tracker. C7a also induced an increase in cytosolic calcium concentration, mainly from intracellular compartments, and a significant decrease in the ATP levels. Activation of effector caspases, chromatin condensation and DNA degradation, suggested that C7a activates the apoptotic intrinsic pathway in murine melanoma cells. In the preclinical studies, the C7a complex protected against murine metastatic melanoma and induced death in several human tumor cell lineages in vitro, including cisplatin-resistant ones. The mitochondria-dependent cell death was also induced by C7a in human tumor cells. The cyclopalladated C7a complex is

  8. ATP-Mediated Compositional Change in Peripheral Myelin Membranes: A Comparative Raman Spectroscopy and Time-Of-Flight Secondary Ion Mass Spectrometry Study.

    Directory of Open Access Journals (Sweden)

    Nikolay Kutuzov

    Full Text Available In the present paper we addressed a mechanism of the myelin reorganization initiated by extracellular ATP and adenosine in sciatic nerves of the frog Rana temporaria. In combination with Raman microspectroscopy, allowing noninvasive live-cell measurements, we employed time-of-flight secondary ion mass spectrometry (TOF-SIMS to follow the underlying changes in chemical composition of myelin membranes triggered by the purinergic agents. The simultaneous increase in lipid ordering degree, decrease in membrane fluidity and the degree of fatty acid unsaturation were induced by both ATP and adenosine. Mass spectrometry measurements revealed that ATP administration also led to the marked elevation of membrane cholesterol and decrease of phosphotidylcholine amounts. Vesicular lipid transport pathways are considered as possible mechanisms of compositional and structural changes of myelin.

  9. ATP-Mediated Compositional Change in Peripheral Myelin Membranes: A Comparative Raman Spectroscopy and Time-Of-Flight Secondary Ion Mass Spectrometry Study.

    Science.gov (United States)

    Kutuzov, Nikolay; Gulin, Alexander; Lyaskovskiy, Vladimir; Nadtochenko, Victor; Maksimov, Georgy

    2015-01-01

    In the present paper we addressed a mechanism of the myelin reorganization initiated by extracellular ATP and adenosine in sciatic nerves of the frog Rana temporaria. In combination with Raman microspectroscopy, allowing noninvasive live-cell measurements, we employed time-of-flight secondary ion mass spectrometry (TOF-SIMS) to follow the underlying changes in chemical composition of myelin membranes triggered by the purinergic agents. The simultaneous increase in lipid ordering degree, decrease in membrane fluidity and the degree of fatty acid unsaturation were induced by both ATP and adenosine. Mass spectrometry measurements revealed that ATP administration also led to the marked elevation of membrane cholesterol and decrease of phosphotidylcholine amounts. Vesicular lipid transport pathways are considered as possible mechanisms of compositional and structural changes of myelin.

  10. Post-irradiation time effects on the graft of poly(ethylene-alt-tetrafluoroethylene) (ETFE) films for ion exchange membrane application

    Science.gov (United States)

    Geraldes, Adriana N.; Zen, Heloísa A.; Ribeiro, Geise; Ferreira, Henrique P.; Souza, Camila P.; Parra, Duclerc F.; Santiago, Elisabete I.; Lugão, Ademar B.

    2010-03-01

    Grafting of styrene followed by sulfonation onto poly(ethylene-alt-tetrafluoroethylene) (ETFE) was studied for synthesis of ion exchange membranes. Radiation-induced grafting of styrene onto ETFE films was investigated after simultaneous irradiation (in post-irradiation condition) using a 60Co source. The ETFE films were irradiated at 20 kGy dose at room temperature and chemical changes were monitored after contact with styrene for grafting. The post-irradiation time was established at 14 days when the films were remained in styrene/toluene 1:1 v/v. After this period the grafting degree was evaluated in the samples. The grafted films were sulfonated using chlorosulfonic acid and 1, 2-dichloroethane 20:80 (v/v) at room temperature for 5 h. The membranes were analyzed by infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), thermogravimetric measurements (TG) and degree of grafting (DOG). The ion exchange capacity (IEC) of membranes was determined by acid-base titration and the values for ETFE membranes were achieved higher than Nafion ® films. Preliminary single cell performance was made using pure H 2 and O 2 as reactants at a cell temperature of 80 °C and atmospheric gas pressure. The fuel cell performance of ETFE films was satisfactory when compared to state-of-art Nafion ® membranes.

  11. Time Domain Reflectometry and Electrical Resistivity Tomography applications for optimizing water use in irrigation

    Science.gov (United States)

    Satriani, A.; Loperte, A.; Catalano, M.

    2012-04-01

    This abstract deals with the joint use of the Time Domain Reflectometry (TDR) and Electrical Resistivity Tomography (ERT) for soil moisture monitoring and spatial distribution estimation in agriculture. In fact, an effective use of irrigation water for a sustainable agriculture helps to cut irrigation cost and the exploitation of technologies for water resource monitoring and management can help to achieve this objective. The work has regarded a flat experimental vegetable area of about 1000 m2 with the bean crop (Phaseolus vulgaris L), which was an subdivided in two adjacent plots of land five meters distant each from other. From sowing and for the whole cultural cycle, irrigation monitoring was performed by using non-invasive surveys, based on measurements of physical properties of the soil, as the dielectric constant and the electrical resistivity. A drip irrigation system was used with the water pumped by a nearby water reserve, represented by a small artificial lake, but a different irrigation treatment was performed for each plot. In the plot A, the irrigation water supply was managed by the farmer, with an intensive irrigation treatment. Differently, in the plot B, the irrigation water supply was decided on the basis of the results of the TDR and ERT surveys. In particular, the amount and the time of irrigation were determined on the basis of the measurements of physical properties of the soil using TDR and ERT, with a specific focus to the soil moisture content estimation and spatial distribution . In fact, during the crop cycle, the soil moisture was measured weekly before and after irrigation, by a 20 cm vertical time domain reflectometry probe located at the center and at the ends of the bean rows. Moreover, the soil water distribution was determined by an electrical resistivity tomography using a multielectrode method. On the basis of the TDR and ERT results, a reduced water supply was performed, which did not affect the bean yield, and moreover

  12. Monitoring water flows with time-lapse Electrical Resistivity Tomography on the Super-Sauze landslide

    Science.gov (United States)

    Gance, J.; Sailhac, P.; Malet, J.-P.; Grandjean, G.; Supper, R.; Jochum, B.; Ottowitz, D.

    2012-04-01

    This work presents results of a permanent hydro-geophysical monitoring of an active landslide developed in clay-shales. Hydrology has been proved to be a major factor controlling the Super-Sauze earthflow behavior, but it knowledge still limited mainly because of the importance of spatial heterogeneities. The geometry of the bedrock creates internal crests and gullies that can guide waterflows or create a lock and engender an excess of pore water pressure; the soil surface characteristics plays also a large role in the surface hydraulic conductivity, and therefore, on the infiltration pattern. To understand in detail these processes, it is therefore important to monitor spatially at large scale (with high resolution) those phenomena and to overcome the monitoring difficulties inherent to a fast-moving clayey earthflow. The objectives of the survey are to identify and characterize spatially and temporarily the water flow circulation within the landslide body over a period of one year. The studied profile measures 114 m long and is surveyed with 93 electrodes spaced from 0.5, 1 or 2 meter according the soil surface cracking. Four resistivity datasets of 4300 measurements are acquired each day using a gradient array since May 2011. The monitoring is performed with the GEOMON4D system, developed by the Geological Survey of Austria. To facilitate the interpretation, humidity, conductivity, temperature, and piezometer sensors are placed along the profile. Two dGPS antenna placed upstream and downstream the profile allow to correlate the results with soil displacement. Lefranc tests and granulometry results realized on several samples have shown the important heterogeneities of the near surface. The objective of this work is to present the data processing strategy for the analysis of long periods time-lapse ERT survey of natural rain events taking into account changes through time of the position of the electrodes, changes in the soil surface state and important changes

  13. Direct prediction of spatially and temporally varying physical properties from time-lapse electrical resistance data

    Science.gov (United States)

    Hermans, Thomas; Oware, Erasmus; Caers, Jef

    2016-09-01

    Time-lapse applications of electrical methods have grown significantly over the last decade. However, the quantitative interpretation of tomograms in terms of physical properties, such as salinity, temperature or saturation, remains difficult. In many applications, geophysical models are transformed into hydrological models, but this transformation suffers from spatially and temporally varying resolution resulting from the regularization used by the deterministic inversion. In this study, we investigate a prediction-focused approach (PFA) to directly estimate subsurface physical properties with electrical resistance data, circumventing the need for classic tomographic inversions. First, we generate a prior set of resistance data and physical property forecast through hydrogeological and geophysical simulations mimicking the field experiment. We reduce the dimension of both the data and the forecast through principal component analysis in order to keep the most informative part of both sets in a reduced dimension space. Then, we apply canonical correlation analysis to explore the relationship between the data and the forecast in their reduced dimension space. If a linear relationship can be established, the posterior distribution of the forecast can be directly sampled using a Gaussian process regression where the field data scores are the conditioning data. In this paper, we demonstrate PFA for various physical property distributions. We also develop a framework to propagate the estimated noise level in the reduced dimension space. We validate the results by a Monte Carlo study on the posterior distribution and demonstrate that PFA yields accurate uncertainty for the cases studied.

  14. Mapping geological structures in bedrock via large-scale direct current resistivity and time-domain induced polarization tomography

    DEFF Research Database (Denmark)

    Rossi, Matteo; Olsson, Per-Ivar; Johansson, Sara

    2017-01-01

    An investigation of geological conditions is always a key point for planning infrastructure constructions. Bedrock surface and rock quality must be estimated carefully in the designing process of infrastructures. A large direct-current resistivity and time-domain induced-polarization survey has......, there are northwest-trending Permian dolerite dykes that are less deformed. Four 2D direct-current resistivity and time-domain induced-polarization profiles of about 1-km length have been carefully pre-processed to retrieve time-domain induced polarization responses and inverted to obtain the direct......-current resistivity distribution of the subsoil and the phase of the complex conductivity using a constant-phase angle model. The joint interpretation of electrical resistivity and induced-polarization models leads to a better understanding of complex three-dimensional subsoil geometries. The results have been...

  15. Space-time clustering of ampicillin resistant Escherichia coli isolated from Danish pigs at slaughter between 1997 and 2005

    DEFF Research Database (Denmark)

    Abatih, E. N.; Ersbøll, A. K.; Wong, Danilo Lo Fo

    2009-01-01

    In Denmark, antimicrobial resistance in bacteria in animals, animal products and humans, is routinely monitored. This study aimed at determining whether the observed variations in the prevalence of ampicillin resistant Escherichia coli isolated from healthy pigs at slaughter were random....... The clusters of ampicillin resistant E coli appeared at the same time as the national consumption of ampicillin in pigs increased, however antimicrobial consumption at the herd level did not appear to have any effects on space-time clustering in this study. The results could serve as a platform to highlight...... or clustered in space and time. Data on E coli isolates between 1997 and 2005 were obtained from the Danish Integrated Antimicrobial Resistance Monitoring and Research Programme (DANMAP) whereas data on the quantity of ampicillin consumed was obtained from the Danish Register of Veterinary Medicines (Vet...

  16. Optimal time for delivery with preterm premature rupture of membranes from 32 to 36 6/7 weeks.

    Science.gov (United States)

    Nold, Christopher; Hussain, Naveed; Smith, Kathleen; Campbell, Winston; Borgida, Adam; Egan, James

    2011-07-01

    To evaluate the optimal time for delivery in singleton pregnancies with preterm premature rupture of membranes (PPROM) when delivered between 32 and 36 6/7 weeks gestational age (GA). We performed a retrospective cohort study of all singleton pregnancies with PPROM who delivered between 32 and 36 6/7 weeks gestation at our institution. We matched the delivery and NICU datasets to determine composite morbidity (COMP MORB) and NICU length of stay (LOS) stratified by weeks of gestation. COMP MORB was defined as one or more of: bronchopulmonary dysplasia, respiratory distress syndrome, necrotizing entercolitis, intraventricular hemorrhage, dissiminated intravascular coagulation, and culture proven sepsis. We used χ² and student 't' test as appropriate and a receiver operating characteristc curve (ROC). There were 195 newborns with PPROM with a range of 30 babies at 36 weeks to a high of 53 at 34 weeks. The mean (± SD) NICU LOS was 22.5 (± 9.9) days at 32 weeks, 17.8 (± 10.0) days at 33 weeks, 14.8 (± 11.0) days at 34 weeks, 4.5 (± 4.7) days at 35 weeks, and 1.5 (± 4.4) days at 36 weeks (p < 0.0001). There was no difference in duration of ROM by GA with a range of 6.8 to 1.9 by week (p = NS). The ROC curve had a cut point for COMP MORB at 34.1 weeks GA (sens = 95%, FPR 48.6%, area under curve 0.782, p = 0.0002). Our study suggests that delivery of PPROM pregnancies at 34.1 weeks GA avoids 95% of composite morbidity, and delivery after 35 weeks GA will decrease the NICU LOS.

  17. Molecular evaluation of colistin-resistant gene expression changes in Acinetobacter baumannii with real-time polymerase chain reaction

    Directory of Open Access Journals (Sweden)

    Sepahvand S

    2017-11-01

    Full Text Available Shahriar Sepahvand,1 Mohammad Ali Davarpanah,2 Amir Roudgari,3 Abbas Bahador,4 Vajihe Karbasizade,5 Zahra Kargar Jahromi6 1Department of Microbiology, Falavarjan Branch, Islamic Azad University, Isfahan, Iran; 2Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran; 3Shiraz Trauma Center, Shiraz University of Medical Sciences, Shiraz, Iran; 4Department of Microbiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran; 5Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran; 6Zoonoses Research Center, Jahrom University of Medical Sciences, Jahrom, Iran Background: Acinetobacter baumannii is an important human pathogen which has recently gained increased attention due to the occurrence of drug-resistant nosocomial infections in patients suffering from immune system disorders, and those in hospital intensive care units. The aim of this research was to identify and isolate A. baumannii strains resistant to colistin, determine antibiotic resistance pattern of this bacteria, investigate the presence of colistin-resistant genes, and finally assess the effect of expression changes in pmrA and pmrB genes resistant to A. baumannii against colistin via real-time polymerase chain reaction.Methods: The samples were initially purified and isolated using biochemical tests and Microgen kit. Later, the resistance pattern evaluation of validated samples to different antibiotics and colistin was carried out using two methods viz., disc diffusion and E-test. This was followed by the assessment of genes resistant to colistin via polymerase chain reaction besides gene expression changes via real-time polymerase chain reaction. Results: The results of this study indicated that eleven strains of A. baumannii isolated from Shahid Rajaee Trauma Hospital were resistant to colistin. However, in the resistance pattern evaluation of A. baumannii isolated

  18. Influenza virus drug resistance: a time-sampled population genetics perspective.

    Directory of Open Access Journals (Sweden)

    Matthieu Foll

    2014-02-01

    Full Text Available The challenge of distinguishing genetic drift from selection remains a central focus of population genetics. Time-sampled data may provide a powerful tool for distinguishing these processes, and we here propose approximate Bayesian, maximum likelihood, and analytical methods for the inference of demography and selection from time course data. Utilizing these novel statistical and computational tools, we evaluate whole-genome datasets of an influenza A H1N1 strain in the presence and absence of oseltamivir (an inhibitor of neuraminidase collected at thirteen time points. Results reveal a striking consistency amongst the three estimation procedures developed, showing strongly increased selection pressure in the presence of drug treatment. Importantly, these approaches re-identify the known oseltamivir resistance site, successfully validating the approaches used. Enticingly, a number of previously unknown variants have also been identified as being positively selected. Results are interpreted in the light of Fisher's Geometric Model, allowing for a quantification of the increased distance to optimum exerted by the presence of drug, and theoretical predictions regarding the distribution of beneficial fitness effects of contending mutations are empirically tested. Further, given the fit to expectations of the Geometric Model, results suggest the ability to predict certain aspects of viral evolution in response to changing host environments and novel selective pressures.

  19. Time Lapse Electrical Resistivity to Connect Evapotranspiration and Groundwater Fluxes in the Critical Zone

    Science.gov (United States)

    Jarvis, S. K.; Harmon, R. E.; Barnard, H. R.; Randall, J.; Singha, K.

    2017-12-01

    The critical zone (CZ)—an open system extending from canopy top to the base of groundwater—is a highly dynamic and heterogeneous environment. In forested terrain, trees make up a large component of the CZ. This work aims to quantify the connection between vegetation and subsurface water storage at a hillslope scale within a forested watershed in the H.J. Andrews Experimental Forest, Oregon. To identify the mechanism(s) controlling the connection at the hillslope scale, we observe patterns in electrical conductivity using 2D-time lapse-DC resistivity. To compare inversions through time a representative error model was determined using L-curve criterion. Inverted data show high spatial variability in ground electrical conductivity and variation at both diel and seasonal timescales. These changes are most pronounced in areas corresponding to dense vegetation. The diel pattern in electrical conductivity is also observed in monitored sap flow sensors, water-level gauges, tensiometers, and sediment thermal probes. To quantify the temporal connection between these data over the course of the growing season a cross correlation analysis was conducted. Preliminary data show that over the course of the growing season transpiration becomes decoupled from both groundwater and soil moisture. Further decomposition of the inverted time lapse data will highlight spatial variability in electrical conductivity providing insight into the where, when, and how(s) of tree-modified subsurface storage.

  20. Space-Time Dynamics of Membrane Currents Evolve to Shape Excitation, Spiking, and Inhibition in the Cortex at Small and Large Scales

    DEFF Research Database (Denmark)

    Roland, Per E.

    2017-01-01

    In the cerebral cortex, membrane currents, i.e., action potentials and other membrane currents, express many forms of space-time dynamics. In the spontaneous asynchronous irregular state, their space-time dynamics are local non-propagating fluctuations and sparse spiking appearing at unpredictable...... positions. After transition to active spiking states, larger structured zones with active spiking neurons appear, propagating through the cortical network, driving it into various forms of widespread excitation, and engaging the network from microscopic scales to whole cortical areas. At each engaged...... cortical site, the amount of excitation in the network, after a delay, becomes matched by an equal amount of space-time fine-tuned inhibition that might be instrumental in driving the dynamics toward perception and action....

  1. Effect of membrane characteristics on the performance of membrane bioreactors for oily wastewater treatment.

    Science.gov (United States)

    Mafirad, S; Mehrnia, M R; Sarrafzadeh, M H

    2011-01-01

    Influence of membrane material and pore size on the performance of a submerged membrane bioreactor (sMBR) for oily wastewater treatment was investigated. The sMBR had a working volume of about 19 L with flat sheet modules at the same hydrodynamic conditions. Five types of micro- and ultra-polymeric membranes containing cellulose acetate (CA), cellulose nitrate (CN), polyamide (PA), polyvinylidene difluoride (PVDF) and polyethersulfone (PES) were used and their filtration performance in terms of permeability, permeate quality and fouling intensity were evaluated. Characterization of the membranes was done by performing some analysis such as pore size distribution; contact angle and scanning electronic microscopy (SEM) microphotograph on all membranes. The quality of permeates from each membrane was identified by measuring chemical oxygen demand (COD). The results showed more irreversible fouling intensity for membranes with larger pore size which can be due to more permeation of bioparticles and colloids inside the pores. Membrane characteristics have a major role in the preliminary time of the filtration before cake layer formation so that the PA with the highest hydrophilicity had the lowest permeability decline by fouling in this period. Also, the PVDF and PES membranes had better performance according to better permeate quality in the preliminary time of the filtration related to smaller pore size and also their better fouling resistance and chemical stability properties. However, all membranes resulted in the same permeability and permeate quality after cake layer formation. An overall efficiency of about 95% in COD removal was obtained for oily wastewater treatment by the membranes used in this study.

  2. Evidence for a role in growth and salt resistance of a plasma membrane H+-ATPase in the root endodermis

    Science.gov (United States)

    Vitart, V.; Baxter, I.; Doerner, P.; Harper, J. F.; Evans, M. L. (Principal Investigator)

    2001-01-01

    The plasma membrane of plant cells is energized by an electrochemical gradient produced by P-type H+-ATPases (proton pumps). These pumps are encoded by at least 12 genes in Arabidopsis. Here we provide evidence that isoform AHA4 contributes to solute transport through the root endodermis. AHA4 is expressed most strongly in the root endodermis and flowers, as suggested by promoter-GUS reporter assays. A disruption of this pump (aha4-1) was identified as a T-DNA insertion in the middle of the gene (after VFP(574)). Truncated aha4-1 transcripts accumulate to approximately 50% of the level observed for AHA4 mRNA in wild-type plants. Plants homozygous for aha4-1 (-/-) show a subtle reduction in root and shoot growth compared with wild-type plants when grown under normal conditions. However, a mutant phenotype is very clear in plants grown under salt stress (e.g., 75 or 110 mM NaCl). In leaves of mutant plants subjected to Na stress, the ratio of Na to K increased 4-5-fold. Interestingly, the aha4-1 mutation appears to be semidominant and was only partially complemented by the introduction of additional wild-type copies of AHA4. These results are consistent with the hypothesis that aha4-1 may produce a dominant negative protein or RNA that partially disrupts the activity of other pumps or functions in the root endodermal tissue, thereby compromising the function of this cell layer in controlling ion homeostasis and nutrient transport.

  3. [Changes of resistant phenotype and CRISPR/Cas system of fourShigellastrains passaged for 90 times without antibiotics].

    Science.gov (United States)

    Zhang, B; Hong, L J; Duan, G C; Liang, W J; Yang, H Y; Xi, Y L

    2017-02-10

    Objective: To explore the stability of resistant phenotypes and changes of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) gene system on four Shigella strains in the absence of antibiotics. Methods: Four clinical isolated Shigella strains that resistant to different antibiotics were consecutive passaged for 90 times without antibiotics. Agar dilution method was used to determine the minimum inhibitory concentration of Shigella strains. After sequence analysis with PCR, CRISPR Finder and Clustal X 2.1 were applied to identify the changes of CRISPR loci in the Shigella strains. Results: After the consecutive transfer of 90 generations, sensitivity to certain antibiotics of four Shigella strains with different drug resistant spectrums increased. Mel-sf1998024/zz resistance to ampicillin, cephalexin, cefotaxime, chloramphenicol decreased, mel-s2014026/sx resistance to norfloxacin, trimethoprim decreased, mel-sf2004004/sx drug resistance to ampicillin, cefuroxime, cefotaxime, chloramphenicol, trimethoprim decreased and mel-sf2013004/bj resistance to chloramphenicol decreased. The spacer of which matched gene codes Cas and its upstream repeat in 3'end of CRISPR3 got lost in mel-sf1998024/zz and mel-sf2013004/bj. Conclusions: Shigella strains could reduce or lose their resistance to some antibiotics after consecutive transfers, without the interference of antibiotics. CRISPR3 locus had dynamic spacers in Shigella strains while CRISPR3 locus and cas genes might have been co-evolved.

  4. Resistance: what is new and on the horizon, and a time to teach old dogs new tricks?

    Science.gov (United States)

    Schapiro, Jonathan

    2014-01-01

    Understanding HIV drug resistance has played a key role in the success of antiretroviral therapy. This knowledge allowed for the prediction of resistance evolution when a specific drug or combinations of drugs were administered, informing strategies implemented for initial and subsequent drug regimens. Resistance testing of individual patients detects transmitted as well as acquired drug resistance as a result of treatment failure, leading to improved treatment choices in drug naïve and drug experienced patients accordingly. The last two decades has seen a great deal of evolution, improvement and change in the care of HIV-positive individuals. Much of this was aimed at preventing, reducing or minimizing the impact of HIV drug resistance. Drugs with much improved resistance characteristics were designed and gained widespread use, as well as those with superior pharmacology and toxicity profiles assisting in better adherence and far reduced failure rates. Patient management strategies and monitoring technologies were refined, and education of clinicians and patients on optimal aspects of care routinely was implemented. All these have led to a new world of HIV clinical care and require a rethinking of how best to use our knowledge of resistance and when, how and in whom to test for it. What lays ahead for HIV drug resistance in the near and distant future, and is it time to teach old dogs new tricks?

  5. Label-free image-based detection of drug resistance with optofluidic time-stretch microscopy (Conference Presentation)

    Science.gov (United States)

    Kobayashi, Hirofumi; Lei, Cheng; Mao, Ailin; Jiang, Yiyue; Guo, Baoshan; Ozeki, Yasuyuki; Goda, Keisuke

    2017-02-01

    Acquired drug resistance is a fundamental predicament in cancer therapy. Early detection of drug-resistant cancer cells during or after treatment is expected to benefit patients from unnecessary drug administration and thus play a significant role in the development of a therapeutic strategy. However, the development of an effective method of detecting drug-resistant cancer cells is still in its infancy due to their complex mechanism in drug resistance. To address this problem, we propose and experimentally demonstrate label-free image-based drug resistance detection with optofluidic time-stretch microscopy using leukemia cells (K562 and K562/ADM). By adding adriamycin (ADM) to both K562 and K562/ADM (ADM-resistant K562 cells) cells, both types of cells express unique morphological changes, which are subsequently captured by an optofluidic time-stretch microscope. These unique morphological changes are extracted as image features and are subjected to supervised machine learning for cell classification. We hereby have successfully differentiated K562 and K562/ADM solely with label-free images, which suggests that our technique is capable of detecting drug-resistant cancer cells. Our optofluidic time-stretch microscope consists of a time-stretch microscope with a high spatial resolution of 780 nm at a 1D frame rate of 75 MHz and a microfluidic device that focuses and orders cells. We compare various machine learning algorithms as well as various concentrations of ADM for cell classification. Owing to its unprecedented versatility of using label-free image and its independency from specific molecules, our technique holds great promise for detecting drug resistance of cancer cells for which its underlying mechanism is still unknown or chemical probes are still unavailable.

  6. Aggregation of Oligoarginines at Phospholipid Membranes: Molecular Dynamics Simulations, Time-Dependent Fluorescence Shift, and Biomimetic Colorimetric Assays

    Czech Academy of Sciences Publication Activity Database

    Vazdar, Mario; Wernersson, Erik; Khabiri, Morteza; Cwiklik, Lukasz; Jurkiewicz, Piotr; Hof, Martin; Mann, E.; Kolusheva, S.; Jelinek, R.; Jungwirth, Pavel

    2013-01-01

    Roč. 117, č. 39 (2013), s. 11530-11540 ISSN 1520-6106 R&D Projects: GA MŠk LH12001; GA ČR GBP208/12/G016 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : cell penetrating peptides * oligoarginine * molecular dynamics * membranes * fluorescence spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.377, year: 2013

  7. Low dose powdered activated carbon addition at high sludge retention times to reduce fouling in membrane bioreactors

    NARCIS (Netherlands)

    Remy, M.J.J.; Marel, van der P.; Zwijnenburg, A.; Rulkens, W.H.; Temmink, B.G.

    2009-01-01

    The addition of a low concentration of PAC (0.5 g L-1 of sludge, i.e. a dose of 4 mg L-1 of wastewater), in combination with a relatively long SRT (50 days), to improve membrane filtration performance was investigated in two pilot-scale MBRs treating real municipal wastewater. Continuous

  8. Determination of the excitation migration time in Photosystem II consequences for the membrane organization and charge separation parameters

    NARCIS (Netherlands)

    Broess, K.; Trinkunas, G.; Hoek, van A.; Croce, R.; Amerongen, van H.

    2008-01-01

    The fluorescence decay kinetics of Photosystem II (PSII) membranes from spinach with open reaction centers (RCs), were compared after exciting at 420 and 484 nm. These wavelengths lead to preferential excitation of chlorophyll (Chl) a and Chl b, respectively, which causes different initial

  9. Determination of the excitation migration time in Photosystem II - Consequences for the membrane organization and charge separation parameters

    NARCIS (Netherlands)

    Broess, Koen; Trinkunas, Gediminas; van Hoek, Arie; Croce, Roberta; van Amerongen, Herbert

    The fluorescence decay kinetics of Photosystem II (PSII) membranes from spinach with open reaction centers (RCs), were compared after exciting at 420 and 484 nm. These wavelengths lead to preferential excitation of chlorophyll (Chl) a and Chl b, respectively, which causes different initial

  10. Determination of the excitation migration time in Photosystem II. Consequences for the membrane organization and charge separation parameters

    NARCIS (Netherlands)

    Broess, Koen; Trinkunas, Gediminas; van Hoek, Arie; Croce, Roberta; van Amerongen, Herbert

    The fluorescence decay kinetics of Photosystem II (PSII) membranes from spinach with open reaction centers (RCs), were compared after exciting at 420 and 484 nm. These wavelengths lead to preferential excitation of chlorophyll (Chl) a and Chl b, respectively, which causes different initial

  11. Low dose powdered activated carbon addition at high sludge retention times to reduce fouling in membrane bioreactors

    NARCIS (Netherlands)

    Remy, Maxime; van der Marel, P.; Zwijnenburg, A.; Rulkens, Wim; Temmink, Hardy

    2009-01-01

    The addition of a low concentration of PAC (0.5 g L−1 of sludge, i.e. a dose of 4 mg L−1 of wastewater), in combination with a relatively long SRT (50 days), to improve membrane filtration performance was investigated in two pilot-scale MBRs treating real municipal wastewater. Continuous

  12. Analysis of Tidal DC Resistivity Time Series for Periodic Saltwater Mixing Patterns and Determination of Hydraulic Ground Properties

    Science.gov (United States)

    Sutter, E. M.; Ingham, M.

    2016-12-01

    Saline intrusion research using geoelectrical time-lapse monitoring, is often directed towards imaging the saltwater-freshwater boundary and the amount of seawater mixing within a coastal aquifer. However, these time series can contain additional information about subsurface hydrologic properties like hydraulic conductivity and permeability which are crucial elements in coastal groundwater management. In this study, DC resistivity time series from tidal time-lapse monitoring surveys of a shallow coastal sand and gravel aquifer in New Zealand have been analysed for recurring patterns of percentage seawater mixing in different portions of the aquifer. The results show a distinctly different behaviour of percentage seawater change with time for several horizontal locations along two profile lines with varying depth. In addition, the geoelectric time series have been cross-correlated with tidal stage data approximated near the survey location in order to find portions of the aquifer that exhibit different time lags with respect to a diurnal tidal cycle. First results yield a remarkably similar picture to resistivity ratios obtained between high and low tide inversion models of the DC resistivity time series both at different locations and for different seasons. The two methods indicate a correlation between rising and falling tides and the resistivity changes observed from geoelectrical monitoring studies .This may be used to distinguish between more or less hydraulically conductive portions of a coastal aquifer.

  13. Effect of Sonification Time on Synthesisi and Corrosion Resistance of Epoxy-Clay Nanocomposite

    Directory of Open Access Journals (Sweden)

    Niloufar Bahrami Panah

    2016-09-01

    Full Text Available In recent years many research works have been carried out on anti-corrosive nanocomposites coatings containing mineral reinforcements. The most important criteria in these attempts are polymerization method and the type of matrix and reinforcement of nanocomposites. In this regard, the physical and mechanical properties of the polymers in which a small amount of filler is used can be improved. In this research, an epoxy-clay nanocomposite was synthesized by in-situ polymerization method using a resin matrix based on bisphenol-A type epoxy and montmorillonite clay (Closite 15A. The treatment was used at different ultrasonic stirring times to disperse 1-4 weight percentages of clay particles into the matrix. The structure of synthesized epoxy-clay nanocomposite was studied by scanning electron microscopy and X-ray diffraction techniques. The average size of clay particles was determined by X-ray diffraction measurement. Then, anti-corrosion properties of epoxy-clay coatings, prepared under different ultrasonic durations and applied on carbon steel panels, were investigated by Tafel and electrochemical impedance spectroscopy techniques. For this purpose, the carbon steel panels coated with these coatings were immersed in 3.5% sodium chloride solution and tested at different immersion times. The results indicated that a nanocomposite containing 1% clay, synthesized, stirred 60 min ultrasonically, produced smaller particle size, lower corrosion current density and higher coating corrosion resistance than the other composite formulations. This nanocomposite provided superior protection against corrosion in sodium chloride solution.

  14. Stabilization of Erythrocyte Membranes by Polyamines

    Science.gov (United States)

    Ballas, Samir K.; Mohandas, Narla; Marton, Laurence J.; Shohet, Stephen B.

    1983-04-01

    Using a laser diffraction technique, we have studied the effects of putrescine, spermidine, and spermine, the three physiologic polyamines, on the deformability and mechanical stability of human erythrocyte membranes. Ghosts resealed with polyamines were subjected to high fluid shear stress in an ektacytometer. All polyamines increased the membrane shear modulus (decreased deformability) in a concentration- and time-dependent manner. The order of effectiveness was spermine > spermidine > putrescine. At 10 μ M, spermine appreciably decreased membrane deformability. For the measurement of membrane mechanical stability, resealed ghosts were subjected to constant high shear stress in the ektacytometer and deformability was continuously recorded as the deformable ghosts fragmented into rigid spherical vesicles. Polyamines, especially spermine, caused a noticeable increase in the t1/2 for fragmentation. These effects could not be ascribed to proteolysis or Ca2+-induced transglutamination. That the effects of polyamines were specific and not simply due to their positive charge was demonstrated by the finding that Ca2+ and Mg2+ destabilized the erythrocyte membrane as evidenced by decreasing the t1/2 for fragmentation. Extracellular polyamines were not effective except under conditions that caused significant accumulation inside the cell. The data indicate that intracellular physiologic polyamines, especially spermine, decrease erythrocyte membrane deformability and stabilize the membrane skeleton, making it more resistant to fragmentation.

  15. Acquired resistance to chlorhexidine - is it time to establish an 'antiseptic stewardship' initiative?

    Science.gov (United States)

    Kampf, G

    2016-11-01

    Chlorhexidine digluconate (CHG) is an antimicrobial agent used for different types of applications in hand hygiene, skin antisepsis, oral care, and patient washing. Increasing use raises concern regarding development of acquired bacterial resistance. Published data from clinical isolates with CHG minimum inhibitory concentrations (MICs) were reviewed and compared to epidemiological cut-off values to determine resistance. CHG resistance is rarely found in Escherichia coli, Salmonella spp., Staphylococcus aureus or coagulase-negative staphylococci. In Enterobacter spp., Pseudomonas spp., Proteus spp., Providencia spp. and Enterococcus spp., however, isolates are more often CHG resistant. CHG resistance may be detected in multi-resistant isolates such as extremely drug-resistant Klebsiella pneumoniae. Isolates with a higher MIC are often less susceptible to CHG for disinfection. Although cross-resistance to antibiotics remains controversial, some studies indicate that the overall exposure to CHG increases the risk for resistance to some antibiotic agents. Resistance to CHG has resulted in numerous outbreaks and healthcare-associated infections. On an average intensive care unit, most of the CHG exposure would be explained by hand hygiene agents when liquid soaps or alcohol-based hand rubs contain CHG. Exposure to sub-lethal CHG concentration may enhance resistance in Acinetobacter spp., K. pneumoniae, and Pseudomonas spp., all species well known for emerging antibiotic resistance. In order to reduce additional selection pressure in nosocomial pathogens it seems to make sense to restrict the valuable agent CHG to those indications with a clear patient benefit and to eliminate it from applications without any benefit or with a doubtful benefit. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  16. Conical Nanopore PC Membranes

    International Nuclear Information System (INIS)

    Clochard, M. C.

    2006-01-01

    Template synthesis can be considered an alternative to conventional lithography methods. It is one way of providing a panel of nanoscale metallic wires, tubes or organic polymeric devices. Our interest is focused on track-etched membranes produced from swift heavy ions bombardment of polymer films. In comparison with self-assembly of block copolymers, this bottom-up approach has the advantage of being economic, it is not time-consuming and it allows track formation of diverse geometries. Tailoring of the conical nanopore tip opening would have a tremendous impact on sensing domain, as well as on fundamental understanding of perpendicular giant magneto Resistance properties observed in metallic multilayered cylindrical nanowires. By combining low-energy heavy ion beam radiation effects with asymmetric etching, the etching temperature and time can be tuned to prepare conical nanopores of controlled geometry from 0.5 to 1μm at the base to a few nanometers at the top. Asymmetric etching onto PC films was pH-monitored at various temperatures in the range of 65 degree to 80 degree. Fluence impact onto track etch pores was also investigated. The pore shape characterization was achieved by electronic microscopy measurements on membrane surfaces and on electrodeposited nanowires. We have also observed a difference in the conical shape of replicated nanowires. Some showed sting shapes and others displayed shell shapes depending on whether a neutralizing agent was used during etching or not

  17. 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...

  18. The Influence of Extractant TOA, Stirring Time on the Extraction ProcessLiquid-liquid, and Liquid Membrane on the Liquid Wastes Containing Cd

    International Nuclear Information System (INIS)

    Prayitno; Djoko-Sardjono; Nurimaniwati; Adhe-Helmayani

    2000-01-01

    The influence of extractant and stirring time on the reduction componentcadmium on liquid wastes has been investigated. The method of experimentalused the extraction with liquid membrane emulsion. The parameters to beinvestigated were extractant amount tri-n octylamine (TOA), duration ofstirring time. In this investigated, extractant amount was varied from 5 to25 % (v/v) TOA, duration of stirring time varied from 5 to minutes. Theresult of experimental can be concluded that the best condition obtained forreducing cadmium component was on extractant amount 20 % (v/v) TOA, stirringtime 25 minutes. The best condition for reducing the cadmium component wasefficiency factor 98.35%. (author)

  19. Characterization of direct methanol fuel cell (DMFC) applications with H{sub 2}SO{sub 4} modified chitosan membrane

    Energy Technology Data Exchange (ETDEWEB)

    Osifo, Peter O.; Masala, Aluwani [Department of Chemical Engineering, Vaal University of Technology, Andries Potgieter Bolevald, P/Bag X021, Vanderbijlpark 1900, Gauteng (South Africa)

    2010-08-01

    Chitosan (Chs) flakes were prepared from chitin materials that were extracted from the exoskeleton of Cape rock lobsters in South Africa. The Chs flakes were prepared into membranes and the Chs membranes were modified by cross-linking with H{sub 2}SO{sub 4}. The cross-linked Chs membranes were characterized for the application in direct methanol fuel cells. The Chs membrane characteristics such as water uptake, thermal stability, proton resistance and methanol permeability were compared to that of high performance conventional Nafion 117 membranes. Under the temperature range studied 20-60 C, the membrane water uptake for Chs was found to be higher than that of Nafion. Thermal analysis revealed that Chs membranes could withstand temperature as high as 230 C whereas Nafion 117 membranes were stable to 320 C under nitrogen. Nafion 117 membranes were found to exhibit high proton resistance of 284 s cm{sup -1} than Chs membranes of 204 s cm{sup -1}. The proton fluxes across the membranes were 2.73 mol cm{sup -2} s{sup -1} for Chs- and 1.12 mol cm{sup -2} s{sup -1} Nafion membranes. Methanol (MeOH) permeability through Chs membrane was less, 1.4 x 10{sup -6} cm{sup 2} s{sup -1} for Chs membranes and 3.9 x 10{sup -6} cm{sup 2} s{sup -1} for Nafion 117 membranes at 20 C. Chs and Nafion membranes were fabricated into membrane electrode assemblies (MAE) and their performances measure in a free-breathing commercial single cell DMFC. The Nafion membranes showed a better performance as the power density determined for Nafion membranes of 0.0075 W cm{sup -2} was 2.7 times higher than in the case of Chs MEA. (author)

  20. RIMS (real-time imprint monitoring by scattering of light) study of pressure, temperature and resist effects on nanoimprint lithography

    International Nuclear Information System (INIS)

    Yu Zhaoning; Gao He; Chou, Stephen Y

    2007-01-01

    To optimize nanoimprint lithography (NIL), it is essential to be able to characterize and control the NIL process in situ and in real time. Recently we have developed a real-time imprint monitoring by the scattering-of-light (RIMS) approach, which allows us to detect the degree of resist deformation and the duration of resist penetration by a mould during the imprint process in real time. In this paper we report the performances of RIMS under a broad range of working conditions. RIMS data shows that the resist penetration is facilitated by increasing processing temperature, pressure and the resist film thickness; a prolonged pre-NIL resist baking step, on the other hand, has the effect of slowing it down. Our results provide further demonstration of the effectiveness of this method under different working conditions. RIMS measurements show not only how long an imprint takes to complete, but also how an imprint progresses with time and how it is affected by differences in processing parameters. These measurements provide information crucial for a better understanding and process optimization in NIL

  1. Evaluating the Impact of Antibiotic Exposures as Time-Dependent Variables on the Acquisition of Carbapenem-Resistant Acinetobacter baumannii.

    Science.gov (United States)

    Munoz-Price, L Silvia; Rosa, Rossana; Castro, Jose G; Laowansiri, Panthipa; Latibeaudiere, Rachel; Namias, Nicholas; Tarima, Sergey

    2016-10-01

    To determine the time-dependent effect of antibiotics on the initial acquisition of carbapenem-resistant Acinetobacter baumannii. Retrospective cohort study. Forty-bed trauma ICU in Miami, FL. All consecutive patients admitted to the unit from November 1, 2010, to November 30, 2011. None. Patients underwent surveillance cultures at admission to the unit and weekly thereafter. The primary outcome was the acquisition of carbapenem-resistant A. baumannii on surveillance cultures. Daily antibiotic exposures during the time of observation were used to construct time-dependent variables, including cumulative exposures (in grams and daily observed doses [defined daily doses]). Among 360 patients, 45 (12.5%) became colonized with carbapenem-resistant A. baumannii. Adjusted Cox models showed that each additional point in the Acute Physiologic and Chronic Health Evaluation score increased the hazard by 4.8% (hazard ratio, 1.048; 95% CI, 1.010-1.087; p = 0.0124) and time-dependent exposure to carbapenems quadrupled the hazard (hazard ratio, 4.087; 95% CI, 1.873-8.920; p = 0.0004) of acquiring carbapenem-resistant A. baumannii. Additionally, adjusted Cox models determined that every additional carbapenem defined daily dose increased the hazard of acquiring carbapenem-resistant A. baumannii by 5.1% (hazard ratio, 1.051; 95% CI, 1.007-1.093; p = 0.0243). Carbapenem exposure quadrupled the hazards of acquiring A. baumannii even after controlling for severity of illness.

  2. Insecticide Resistance Management

    Science.gov (United States)

    2013-01-01

    thuringiensis var. membranes israeknsis A2 Bacillus sphaencus Inhibitocs of chitin biosynthesis type 0 15 Benzaylureas Diflubenzuron, triflnmuron...resources/ pdf /fsp/ir_manual/ir_cdc_bioassay_en.pdf 22 STEP 5: INTERPRETING RESULTS The time required for all susceptible mosquitoes to die in the...purchase by contacting: Dr Zairi Jaal, Tel: 604-6574776; zairi@usm.my http://www.who.int/whopes/resistance/en/WHO_CDS_CPE_PV C_2001.2. pdf 27

  3. Effects of filtration modes on membrane fouling behavior and treatment in submerged membrane bioreactor.

    Science.gov (United States)

    Maqbool, Tahir; Khan, Sher Jamal; Lee, Chung-Hak

    2014-11-01

    Relaxation or backwashing is obligatory for effective operation of membrane module and intermittent aeration is helpful for nutrients removal. This study was performed to investigate effects of different filtration modes on membrane fouling behavior and treatment in membrane bioreactor (MBR) operated at three modes i.e., 12, 10 and 8min filtration and 3, 2, and 2min relaxation corresponding to 6, 5 and 4cycles/hour, respectively. Various parameters including trans-membrane pressure, specific cake resistance, specific oxygen uptake rate, nutrients removal and sludge dewaterability were examined to optimize the filtration mode. TMP profiles showed that MBR(8+2) with 8min filtration and 2min relaxation reduced the fouling rate and depicted long filtration time in MBR treating synthetic wastewater. MBR(12+3) was more efficient in organic and nutrients removal while denitrification rate was high in MBR(8+2). Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Helicobacter pylori antibiotic resistance in a Dutch region: trends over time.

    NARCIS (Netherlands)

    Janssen, M.J.R.; Hendrikse, L.; Boer, S.Y. de; Bosboom, R.; Boer, W.A. de; Laheij, R.J.F.; Jansen, J.B.M.J.

    2006-01-01

    AIM: Most patients treated for H. pylori infection receive empirical therapy based on epidemiological data of antibiotic resistance. However, previous European studies indicate that resistance patterns may be changing. Therefore, the aim of this study was to investigate the prevalence of primary

  5. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

    Science.gov (United States)

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-11-01

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl-/SO42- separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl-/SO42- permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later.

  6. TA [B] Predicting Microstructure-Creep Resistance Correlation in High Temperature Alloys over Multiple Time Scales

    Energy Technology Data Exchange (ETDEWEB)

    Tomar, Vikas [Purdue Univ., West Lafayette, IN (United States)

    2017-03-06

    DoE-NETL partnered with Purdue University to predict the creep and associated microstructure evolution of tungsten-based refractory alloys. Researchers use grain boundary (GB) diagrams, a new concept, to establish time-dependent creep resistance and associated microstructure evolution of grain boundaries/intergranular films GB/IGF controlled creep as a function of load, environment, and temperature. The goal was to conduct a systematic study that includes the development of a theoretical framework, multiscale modeling, and experimental validation using W-based body-centered-cubic alloys, doped/alloyed with one or two of the following elements: nickel, palladium, cobalt, iron, and copper—typical refractory alloys. Prior work has already established and validated a basic theory for W-based binary and ternary alloys; the study conducted under this project extended this proven work. Based on interface diagrams phase field models were developed to predict long term microstructural evolution. In order to validate the models nanoindentation creep data was used to elucidate the role played by the interface properties in predicting long term creep strength and microstructure evolution.

  7. Time-dependent free boundary equilibrium and resistive diffusion in a tokamak plasma

    International Nuclear Information System (INIS)

    Selig, G.

    2012-12-01

    In a Tokamak, in order to create the necessary conditions for nuclear fusion to occur, a plasma is maintained by applying magnetic fields. Under the hypothesis of an axial symmetry of the tokamak, the study of the magnetic configuration at equilibrium is done in two dimensions, and is deduced from the poloidal flux function. This function is solution of a non linear partial differential equation system, known as equilibrium problem. This thesis presents the time dependent free boundary equilibrium problem, where the circuit equations in the tokamak coils and passive conductors are solved together with the Grad-Shafranov equation to produce a dynamic simulation of the plasma. In this framework, the Finite Element equilibrium code CEDRES has been improved in order to solve the aforementioned dynamic problem. Consistency tests and comparisons with the DINA-CH code on an ITER vertical instability case have validated the results. Then, the resistive diffusion of the plasma current density has been simulated using a coupling between CEDRES and the averaged one-dimensional diffusion equation, and it has been successfully compared with the integrated modeling code CRONOS. (author)

  8. Shortened Time to Identify Staphylococcus Species from Blood Cultures and Methicillin Resistance Testing Using CHROMAgar

    Directory of Open Access Journals (Sweden)

    Shingo Chihara

    2009-01-01

    Full Text Available The ability to rapidly differentiate coagulase-negative staphylococcus (CoNS from Staphylococcus aureus and to determine methicillin resistance is important as it affects the decision to treat empiric antibiotic selection. The objective of this study was to evaluate CHROMagar S. aureus and CHROMagar MRSA (Becton Dickinson for rapid identification of Staphylococcus spp. directly from blood cultures. Consecutive blood culture bottles (BacT Alert 3D SA and SN, bioMérieux growing gram-positive cocci in clusters were evaluated. An aliquot was plated onto CHROMagar MRSA (C-MRSA and CHROMagar S. aureus (C-SA plates, which were read at 12 to 16 hours. C-SA correctly identified 147/147 S. aureus (100% sensitivity; 2 CoNS were misidentified as S. aureus (98% specificity. C-MRSA correctly identified 74/77 MRSA (96% sensitivity. None of the MSSA isolates grew on C-MRSA (100% specificity. In conclusion, CHROMagar is a rapid and sensitive method to distinguish MRSA, MSSA, and coagulase-negative Staphylococcus and may decrease time of reporting positive results.

  9. High force development augments skeletal muscle signalling in resistance exercise modes equalized for time under tension.

    Science.gov (United States)

    Gehlert, Sebastian; Suhr, Frank; Gutsche, Katrin; Willkomm, Lena; Kern, Julia; Jacko, Daniel; Knicker, Axel; Schiffer, Thorsten; Wackerhage, Henning; Bloch, Wilhelm

    2015-06-01

    How force development and time under tension (TUT) during resistance exercise (RE) influence anabolic signalling of skeletal muscle is incompletely understood. We hypothesized that high force development during RE is more important for post-exercise-induced signalling than submaximal and fatiguing RE with lower force development but similar TUT. Twenty-two male subjects (24 ± 6 years, 181 ± 9 cm, 79 ± 2 kg) performed three distinct RE modes in the fed state with equal TUT but distinct force output: (i) maximal eccentric RE (ECC, n = 7) three sets, eight reps, 100% eccentric dynamic force; (ii) standard RE (STD, n = 7), three sets, 10 reps, 75% dynamic force; and (iii) high fatiguing single-set RE (HIT, n = 8), 20 reps, 100% eccentric-concentric force; vastus lateralis biopsies were collected at baseline, 15, 30, 60, 240 min and 24 h after RE, and the signalling of mechanosensitive and mammalian target of rapamycin (mTOR)-related proteins was determined. The phosphorylation levels of pFAK(Tyr397), pJNK(Thr183/Tyr185), pAKT(Thr308/Ser473), pmTOR(Ser2448), p4E-BP1(Thr37/46), p70s6k(Thr389)/(Ser421/Thr424) and pS6(Ser235/236) were significantly higher in ECC than those in STD and HIT at several time points (P force development during acute RE is superior for anabolic skeletal muscle signalling than fatiguing RE with lower force output but similar TUT. Our results suggest that this response is substantially driven by the higher activation of type II myofibres during RE.

  10. BEHAVIOR OF DELAYED ADDITION TIME OF SNF SUPERPLASTICIZER ON MICROSILICA-SULPHATE RESISTING CEMENTS

    Directory of Open Access Journals (Sweden)

    El-Didamony H.

    2013-09-01

    Full Text Available Most concrete produced today includes either chemical additions or chemical admixtures added to concrete, or both. These additives alter the properties of cementitious systems, including fluidity, hydration kinetics, microstructure and strength. Therefore, the development and use of the most suitable type, optimum dosage and delayed addition time (DAT of superplasticiser in concrete technology have been of increasing importance. The present investigation aimed to evaluate the influence of DAT of sulfonated naphthalene formaldehyde (SNF condensate on the hydration kinetics of sulfate resisting cement (SRC pastes incorporating 10 mass % silica fume (SF. Superplasticized cement pastes were prepared using the required water of standard consistency with different dosages and DAT of SNF. The pastes were hydrated for 90 days under normal curing conditions. The results revealed that, the fluidity of cement pastes increases with SNF content and DAT up to 7.5 minutes, due to the electrostatic repulsion between cement particles and the decrease of anhydrous C3A content that is minimized with hydration time. Also, the chemical and physico-mechanical characteristics improve with superplasticizer dosage up to 1.0 mass % and DAT up to 7.5 minutes, due to the improvement of superplasticizing effect, leading to increase the hydration of silicate phases (C3S and β-C2S and formation of more CSH, CAH and CASH. These hydrates increase the gel/space ratio, modify the microstructure and consequently enhance the strength of cement paste. FTIR spectra are in a good agreement with those of chemical and physico–mechanical characteristics.

  11. Tetrakis-amido high flux membranes

    Science.gov (United States)

    McCray, S.B.

    1989-10-24

    Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

  12. Quantitative detection of Cucumber vein yellowing virus in susceptible and partially resistant plants using real-time PCR.

    Science.gov (United States)

    Picó, Belén; Sifres, Alicia; Nuez, Fernando

    2005-09-01

    A method for the detection of Cucumber vein yellowing virus (CVYV) that combines reverse transcription with real-time PCR (SYBR((R)) Green chemistry) was developed using specific primers designed from a nucleotide sequence of the RNA polymerase gene (NIb) conserved among all the available CVYV strains. This method provided a linear assay over five to six orders of magnitude and reproducibly detected titres as low as 10(3) molecules of the target CVYV cDNA. Real-time PCR gave reproducible results for the quantification of CVYV in young leaves of susceptible and resistant cucumber landraces after mechanical inoculation. Significant differences in the starting amount of target cDNA were found between the analyzed genotypes, indicating differences in viral accumulation that correlated to their different levels of resistance. Real-time PCR results validated our previous findings using slot-blot hybridization, the dominance of the strong resistance to CVYV displayed by C.sat 10, and provided improved reliability and sensitivity of detection. This method has great potential in resistance breeding for germplasm screening, characterization of resistance mechanisms and genetic studies.

  13. Synthesis of superhydrophobic alumina membrane: Effects of sol-gel coating, steam impingement and water treatment

    Science.gov (United States)

    Ahmad, N. A.; Leo, C. P.; Ahmad, A. L.

    2013-11-01

    Ceramic membranes possess natural hydrophilicity thus tending to absorb water droplets. The absorption of water molecules on membrane surface reduces their application in filtration, membrane distillation, osmotic evaporation and membrane gas absorption. Fluoroalkylsilane (FAS) grafting allows the conversion of hydrophilic ceramic membranes into superhydrophobic thin layer, but it usually introduces a great increment of mass transfer resistance. In this study, superhydrophobic alumina membranes were synthesized by dip coating alumina support into sol-gel and grafted with the fluoroalkylsilane (FAS) named (heptadecafluoro-1,1,2,2-tetra hydrodecyl) triethoxysilane. Steam impingement and water treatment acted as additional steps to generate surface roughness on sol-gel and most importantly to reduce mass transfer resistance. Superhydrophobic alumina membrane with high water contact angle (158.4°) and low resistance (139.5 ± 24.9 G m-1) was successfully formed when the alumina membrane was dip coated into sol-gel for 7 s, treated with steam impingement for 1 min and immersed in hot water at 100 °C. However, the mass transfer resistance was greatly induced to 535.6 ± 23.5 G m-1 when the dip coating time was increased to 60 s. Long dip coating time contributes more on the blockage of porous structure rather than creates a thin film on the top of membrane surface. Reducing the pore size and porosity significantly due to increase of coating molecules deposited on the membrane. Steam impingement for 1 min promoted the formation of cones and valleys on the sol-gel, but the macro-roughness was destroyed when the steam impingement duration was extended to more than 3 min. The immersions of membranes into hot water at temperatures higher than 60 °C encouraged the formation of boehmite which enhances the formation of additional roughness and enlarges pore size greatly. Thus, this work showed that the formation of superhydrophobic alumina membrane with low resistance is

  14. Increased breathing resistance compromises the time course of rhythmical forearm movements-a pilot study.

    Science.gov (United States)

    Tabary, Ariane; Rassler, Beate

    2015-01-01

    Skeletal muscle dysfunction is a major problem among the co-morbidities associated with chronic obstructive pulmonary disease (COPD). However, muscle weakness and increased fatigability are not the only limitations of skeletal muscle function. Motor-respiratory coordination (MRC) may occur even during movements at lowest workloads. MRC modifies the temporal pattern of motor actions, thus probably impairing motor performance and movement precision. Little attention has been paid to the question of whether motor functions may be compromised in COPD patients independent of workload and required muscle strength and endurance. The present pilot study was designed to investigate the effects of a simulated obstruction (SO) in healthy subjects on their breathing pattern and the timing of a rhythmical forearm movement. Twenty-one subjects performed flexion- extension movements with their right forearm at a self-chosen rate within a range between 0.2 and 0.4 Hz. After a control experiment with normal breathing, a plug with a narrow hole was inserted between face mask and pneumotachograph to simulate obstruction. Subjects were required to repeat the rhythmical forearm movement at the same rate as in the control experiment. The condition of SO significantly prolonged breath duration but reduced tidal volume and ventilation. In addition, period duration of the forearm movement increased significantly under this condition while the movement-to-breathing frequency ratio remained almost constant. Increased breathing resistance was considered to cause prolonged breath duration accompanied by an increase in movement period duration. The constant near-integer ratio between movement and breathing rates indicates that the change in movement period duration resulted from MRC. The findings of this pilot study demonstrate that increased breathing resistance may compromise motor performance even at lower workloads. This means that in COPD patients, not only muscle strength and endurance

  15. Improved permeation performance and fouling-resistance of Poly(vinyl chloride/Polycarbonate blend membrane with added Pluronic F127

    Directory of Open Access Journals (Sweden)

    Supateekan Pacharasakoolchai

    2014-04-01

    Full Text Available The aim of this work was to prepare and characterize poly(vinyl chloride (PVC/polycarbonate (PC blend membranes for use in ultrafiltration. Pluronic F127 was used as an additive to modify the membrane surface of the PVC/PC blended membranes. The PVC/PC blend membrane was first prepared using the phase inversion method from a casting solution of PVC with small amount of PC in N-methylpyrrolidone (NMP and water as the non-solvent. The morphologies structure and properties, such as tensile strength, water flux, and bovine serum albumin (BSA rejection of the blend membrane were studied. Increased amounts of PC resulted in an increase in the water flux and ability to reject protein. A concentration of 0.75 wt% PC provided the best improvement in tensile strength of blend membrane. Addition of different amounts of pluronic F127 to the casting solution of PVC/PC with a PC concentration of 0.75 wt% resulted in a decrease in the water contact angle that demonstrated the improvement of hydrophilicity of blend membrane. Scanning electron microscopy photographs showed that the modified PVC/PC membranes had a bigger pore volume in the porous sub-layer compared to the PVC/PC control membrane. The PVC/PC membrane with added Pluronic F127 exhibited a much higher flux and rejection of BSA in a protein filtration experiment than the PVC/PC membrane. An increase in flux recovery ratio of PVC/PC/pluronic 127 blend membrane indicated that the modified membranes could reduce membrane fouling useful for ultrafiltration.

  16. Decreased Time to Treatment Initiation for Multidrug-Resistant Tuberculosis Patients after Use of Xpert MTB/RIF Test, Latvia.

    Science.gov (United States)

    Stagg, Helen R; White, Peter J; Riekstiņa, Vija; Cīrule, Andra; Šķenders, Ģirts; Leimane, Vaira; Kuksa, Liga; Dravniece, Gunta; Brown, James; Jackson, Charlotte

    2016-03-01

    Few studies have examined whether the Xpert MTB/RIF test improves time to treatment initiation for persons with multidrug-resistant tuberculosis (MDR TB). We determined the impact of this test in Latvia, where it was introduced in 2010. After descriptive analyses of pulmonary MDR TB patients in Latvia during 2009-2012, time to treatment initiation was calculated, and univariate and multivariable accelerated failure time models were constructed. Univariate results showed strong evidence of an association between having rifampin-resistant TB detected by Xpert MTB/RIF and reduced time to treatment initiation versus the test not being used. A multivariable model stratifying by previous TB showed similar results. Our finding that in Latvia, time to treatment initiation was decreased for MDR TB cases that were rifampin-resistant TB by XpertMTB/RIF has implications for the use of this test in other settings with a high burden of MDR TB in which rifampin resistance is highly predictive of MDR TB.

  17. Usefulness of Multiplex Real-Time PCR for Simultaneous Pathogen Detection and Resistance Profiling of Staphylococcal Bacteremia

    Directory of Open Access Journals (Sweden)

    Yousun Chung

    2016-01-01

    Full Text Available Staphylococci are the leading cause of nosocomial blood stream infections. Fast and accurate identification of staphylococci and confirmation of their methicillin resistance are crucial for immediate treatment with effective antibiotics. A multiplex real-time PCR assay that targets mecA, femA specific for S. aureus, femA specific for S. epidermidis, 16S rRNA for universal bacteria, and 16S rRNA specific for staphylococci was developed and evaluated with 290 clinical blood culture samples containing Gram-positive cocci in clusters (GPCC. For the 262 blood cultures identified to the species level with the MicroScan WalkAway system (Siemens Healthcare Diagnostics, USA, the direct real-time PCR assay of positive blood cultures showed very good agreement for the categorization of staphylococci into methicillin-resistant S. aureus (MRSA, methicillin-susceptible S. aureus (MSSA, methicillin-resistant S. epidermidis (MRSE, methicillin-susceptible S. epidermidis (MSSE, methicillin-resistant non-S. epidermidis CoNS (MRCoNS, and methicillin-susceptible non-S. epidermidis CoNS (MSCoNS (κ=0.9313. The direct multiplex real-time PCR assay of positive blood cultures containing GPCC can provide essential information at the critical point of infection with a turnaround time of no more than 4 h. Further studies should evaluate the clinical outcome of using this rapid real-time PCR assay in glycopeptide antibiotic therapy in clinical settings.

  18. Inhibition of the multidrug resistance P-glycoprotein: time for a change of strategy?

    Science.gov (United States)

    Callaghan, Richard; Luk, Frederick; Bebawy, Mary

    2014-04-01

    P-glycoprotein (P-gp) is a key player in the multidrug-resistant phenotype in cancer. The protein confers resistance by mediating the ATP-dependent efflux of an astonishing array of anticancer drugs. Its broad specificity has been the subject of numerous attempts to inhibit the protein and restore the efficacy of anticancer drugs. The general strategy has been to develop compounds that either compete with anticancer drugs for transport or act as direct inhibitors of P-gp. Despite considerable in vitro success, there are no compounds currently available to "block" P-gp-mediated resistance in the clinic. The failure may be attributed to toxicity, adverse drug interaction, and numerous pharmacokinetic issues. This review provides a description of several alternative approaches to overcome the activity of P-gp in drug-resistant cells. These include 1) drugs that specifically target resistant cells, 2) novel nanotechnologies to provide high-dose, targeted delivery of anticancer drugs, 3) compounds that interfere with nongenomic transfer of resistance, and 4) approaches to reduce the expression of P-gp within tumors. Such approaches have been developed through the pursuit of greater understanding of resistance mediators such as P-gp, and they show considerable potential for further application.

  19. Hydrogen bond strength in membrane proteins probed by time-resolved1H-detected solid-state NMR and MD simulations.

    Science.gov (United States)

    Medeiros-Silva, João; Jekhmane, Shehrazade; Baldus, Marc; Weingarth, Markus

    2017-10-01

    1 H-detected solid-state NMR in combination with 1 H/ 2 D exchange steps allows for the direct identification of very strong hydrogen bonds in membrane proteins. On the example of the membrane-embedded potassium channel KcsA, we quantify the longevity of such very strong hydrogen bonds by combining time-resolved 1 H-detected solid-state NMR experiments and molecular dynamics simulations. In particular, we show that the carboxyl-side chain of the highly conserved residue Glu51 is involved in ultra-strong hydrogen bonds, which are fully-water-exposed and yet stable for weeks. The astonishing stability of these hydrogen bonds is important for the structural integrity of potassium channels, which we further corroborate by computational studies. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  20. Analysis on the arcelin expression in bruchid pest resistant wild pulses using real time RT-qPCR.

    Science.gov (United States)

    Sakthivelkumar, Shanmugavel; Veeramani, Velayutham; Hilda, Karuppiah; Arumugam, Munusamy; Janarthanan, Sundaram

    2014-12-01

    Arcelin, the antimetabolic protein from wild pulses is a known natural insecticidal molecule. Wild pulses with high arcelin content could serve as potential source to. increase the levels of insect resistance in cultivated pulse crops. In this study, arcelin (Arl) gene expression was screened in seven stored product insect pest resistant wild pulse varieties using real time RT-qPCR. Arcelin gene specific real time PCR primers were synthesized from arcelin mRNA sequence of the wild pulse variety, Lablab purpureus. The results revealed different levels of arcelin gene expression in the tested varieties. Canavalia virosa registered significantly high content indicating its suitability for utilization of arcelin gene in developing stored product insect pest resistance with other cultivated pulses.

  1. Tension-induced fusion of bilayer membranes and vesicles

    Science.gov (United States)

    Shillcock, Julian C.; Lipowsky, Reinhard

    2005-03-01

    Maintaining the integrity of their protective plasma membrane is a primary requirement of cells. Accordingly, cellular events that breach the membrane are tightly regulated. Artificial vesicles used in drug delivery must also stay intact until they have reached the desired target. In both cases, the intrinsic resistance of the membrane to rupture must be overcome to allow the efflux of the vesicle's contents. Here, we use mesoscopic simulations to study the fusion of 28-nm-diameter vesicles to 50 × 50 nm2 planar membrane patches over 2 μs. We monitor the time evolution of 93 different fusion attempts. This allows us to construct a global morphology diagram, using the initial tensions of the vesicle and the planar membrane patch as control parameters, and to determine the corresponding fusion statistics. All successful fusion events are observed to occur within 350 ns, which reflects the presence of alternative pathways for the tension relaxation.

  2. High nasal resistance is stable over time but poorly perceived in people with tetraplegia and obstructive sleep apnoea.

    Science.gov (United States)

    Wijesuriya, Nirupama S; Lewis, Chaminda; Butler, Jane E; Lee, Bonsan B; Jordan, Amy S; Berlowitz, David J; Eckert, Danny J

    2017-01-01

    Obstructive sleep apnoea (OSA) is highly prevalent in people with tetraplegia. Nasal congestion, a risk factor for OSA, is common in people with tetraplegia. The purpose of this study was to quantify objective and perceived nasal resistance and its stability over four separate days in people with tetraplegia and OSA (n=8) compared to able-bodied controls (n=6). Awake nasal resistance was quantified using gold standard choanal pressure recordings (days 1 and 4) and anterior rhinomanometry (all visits). Nasal resistance (choanal pressure) was higher in people with tetraplegia versus controls (5.3[6.5] vs. 2.1[2.4] cmH 2 O/L/s, p=0.02) yet perceived nasal congestion (modified Borg score) was similar (0.5[1.8] vs. 0.5[2.0], p=0.8). Nasal resistance was stable over time in both groups (CV=0.23±0.09 vs. 0.16±0.08, p=0.2). These findings are consistent with autonomic dysfunction in tetraplegia and adaptation of perception to high nasal resistance. Nasal resistance may be an important therapeutic target for OSA in this population but self-assessment cannot reliably identify those most at risk. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Impacts of solids retention time on trace organic compound attenuation and bacterial resistance to trimethoprim and sulfamethoxazole.

    Science.gov (United States)

    Neyestani, Majid; Dickenson, Eric; McLain, Jean; Robleto, Eduardo; Rock, Channah; Gerrity, Daniel

    2017-09-01

    Bacteria can grow in the presence of trimethoprim and sulfamethoxazole by expressing antibiotic resistance genes or by acquiring thymine or thymidine from environmental reservoirs to facilitate DNA synthesis. The purpose of this study was to evaluate whether activated sludge serves as a reservoir for thymine or thymidine, potentially impacting the quantification of antibiotic resistant bacteria. This study also assessed the impacts of varying solids retention time (SRT) on trimethoprim and sulfamethoxazole removal during wastewater treatment and single and multi-drug resistance. When assayed in the presence of the antibiotics at standard clinical concentrations, up to 40% increases in the relative prevalence of resistant bacteria were observed with (1) samples manually augmented with reagent-grade thymidine, (2) samples manually augmented with sonicated biomass (i.e., cell lysate), (3) samples manually augmented with activated sludge filtrate, and (4) activated sludge samples collected from reactors with longer SRTs. These observations suggest that longer SRTs may select for antibiotic resistant bacteria and/or result in false positives for antibiotic resistance due to higher concentrations of free thymine, thymidine, or other extracellular constituents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Effects of Chicken Litter Storage Time and Ammonia Content on Thermal Resistance of Desiccation-Adapted Salmonella spp.

    Science.gov (United States)

    Chen, Zhao; Wang, Hongye; Ionita, Claudia; Luo, Feng; Jiang, Xiuping

    2015-10-01

    Broiler chicken litter was kept as a stacked heap on a poultry farm, and samples were collected up to 9 months of storage. Chicken litter inoculated with desiccation-adapted Salmonella cells was heat-treated at 75, 80, 85, and 150°C. Salmonella populations decreased in all these samples during heat treatment, and the inactivation rates became lower in chicken litter when storage time was extended from 0 to 6 months. There was no significant difference (P > 0.05) in thermal resistance of Salmonella in 6- and 9-month litter samples, indicating that a threshold for thermal resistance was reached after 6 months. Overall, the thermal resistance of Salmonella in chicken litter was affected by the storage time of the litter. The changes in some chemical, physical, and microbiological properties during storage could possibly contribute to this difference. Moisture and ammonia could be two of the most significant factors influencing the thermal resistance of Salmonella cells in chicken litter. Our results emphasize the importance of adjusting time and temperature conditions for heat processing chicken litter when it is removed from the chicken house at different time intervals. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  5. Objectively measured sedentary time may predict insulin resistance independent of moderate- and vigorous-intensity physical activity

    NARCIS (Netherlands)

    Helmerhorst, Hendrik J. F.; Wijndaele, Katrien; Brage, Søren; Wareham, Nicholas J.; Ekelund, Ulf

    2009-01-01

    To examine the prospective association between objectively measured time spent sedentary and insulin resistance and whether this association is independent of moderate- and vigorous-intensity physical activity (MVPA) and other relevant confounders. This was a population-based study (Medical Research

  6. Time-Scaled Evolutionary Analysis of the Transmission and Antibiotic Resistance Dynamics of Staphylococcus aureus Clonal Complex 398.

    Science.gov (United States)

    Ward, M J; Gibbons, C L; McAdam, P R; van Bunnik, B A D; Girvan, E K; Edwards, G F; Fitzgerald, J R; Woolhouse, M E J

    2014-12-01

    Staphylococcus aureus clonal complex 398 (CC398) is associated with disease in humans and livestock, and its origins and transmission have generated considerable interest. We performed a time-scaled phylogenetic analysis of CC398, including sequenced isolates from the United Kingdom (Scotland), along with publicly available genomes. Using state-of-the-art methods for mapping traits onto phylogenies, we quantified transitions between host species to identify sink and source populations for CC398 and employed a novel approach to investigate the gain and loss of antibiotic resistance in CC398 over time. We identified distinct human- and livestock-associated CC398 clades and observed multiple transmissions of CC398 from livestock to humans and between countries, lending quantitative support to previous reports. Of note, we identified a subclade within the livestock-associated clade comprised of isolates from hospital environments and newborn babies, suggesting that livestock-associated CC398 is capable of onward transmission in hospitals. In addition, our analysis revealed significant differences in the dynamics of resistance to methicillin and tetracycline related to contrasting historical patterns of antibiotic usage between the livestock industry and human medicine. We also identified significant differences in patterns of gain and loss of different tetracycline resistance determinants, which we ascribe to epistatic interactions between the resistance genes and/or differences in the modes of inheritance of the resistance determinants. Copyright © 2014 Ward et al.

  7. Mi-1-Mediated Nematode Resistance in Tomatoes is Broken by Short-Term Heat Stress but Recovers Over Time.

    Science.gov (United States)

    Marques de Carvalho, Luciana; Benda, Nicole D; Vaughan, Martha M; Cabrera, Ana R; Hung, Kaddie; Cox, Thomas; Abdo, Zaid; Allen, L Hartwell; Teal, Peter E A

    2015-06-01

    Tomato (Solanum lycopersicum L.) is among the most valuable agricultural products, but Meloidogyne spp. (root-knot nematode) infestations result in serious crop losses. In tomato, resistance to root-knot nematodes is controlled by the gene Mi-1, but heat stress interferes with Mi-1-associated resistance. Inconsistent results in published field and greenhouse experiments led us to test the effect of short-term midday heat stress on tomato susceptibility to Meloidogyne incognita race 1. Under controlled day/night temperatures of 25°C/21°C, 'Amelia', which was verified as possessing the Mi-1 gene, was deemed resistant (4.1 ± 0.4 galls/plant) and Rutgers, which does not possess the Mi-1 gene, was susceptible (132 ± 9.9 galls/plant) to M. incognita infection. Exposure to a single 3 hr heat spike of 35°C was sufficient to increase the susceptibility of 'Amelia' but did not affect Rutgers. Despite this change in resistance, Mi-1 gene expression was not affected by heat treatment, or nematode infection. The heat-induced breakdown of Mi-1 resistance in 'Amelia' did recover with time regardless of additional heat exposures and M. incognita infection. These findings would aid in the development of management strategies to protect the tomato crop at times of heightened M. incognita susceptibility.

  8. The timing and targeting of treatment in influenza pandemics influences the emergence of resistance in structured populations.

    Science.gov (United States)

    Althouse, Benjamin M; Patterson-Lomba, Oscar; Goerg, Georg M; Hébert-Dufresne, Laurent

    2013-01-01

    Antiviral resistance in influenza is rampant and has the possibility of causing major morbidity and mortality. Previous models have identified treatment regimes to minimize total infections and keep resistance low. However, the bulk of these studies have ignored stochasticity and heterogeneous contact structures. Here we develop a network model of influenza transmission with treatment and resistance, and present both standard mean-field approximations as well as simulated dynamics. We find differences in the final epidemic sizes for identical transmission parameters (bistability) leading to different optimal treatment timing depending on the number initially infected. We also find, contrary to previous results, that treatment targeted by number of contacts per individual (node degree) gives rise to more resistance at lower levels of treatment than non-targeted treatment. Finally we highlight important differences between the two methods of analysis (mean-field versus stochastic simulations), and show where traditional mean-field approximations fail. Our results have important implications not only for the timing and distribution of influenza chemotherapy, but also for mathematical epidemiological modeling in general. Antiviral resistance in influenza may carry large consequences for pandemic mitigation efforts, and models ignoring contact heterogeneity and stochasticity may provide misleading policy recommendations.

  9. The timing and targeting of treatment in influenza pandemics influences the emergence of resistance in structured populations.

    Directory of Open Access Journals (Sweden)

    Benjamin M Althouse

    Full Text Available Antiviral resistance in influenza is rampant and has the possibility of causing major morbidity and mortality. Previous models have identified treatment regimes to minimize total infections and keep resistance low. However, the bulk of these studies have ignored stochasticity and heterogeneous contact structures. Here we develop a network model of influenza transmission with treatment and resistance, and present both standard mean-field approximations as well as simulated dynamics. We find differences in the final epidemic sizes for identical transmission parameters (bistability leading to different optimal treatment timing depending on the number initially infected. We also find, contrary to previous results, that treatment targeted by number of contacts per individual (node degree gives rise to more resistance at lower levels of treatment than non-targeted treatment. Finally we highlight important differences between the two methods of analysis (mean-field versus stochastic simulations, and show where traditional mean-field approximations fail. Our results have important implications not only for the timing and distribution of influenza chemotherapy, but also for mathematical epidemiological modeling in general. Antiviral resistance in influenza may carry large consequences for pandemic mitigation efforts, and models ignoring contact heterogeneity and stochasticity may provide misleading policy recommendations.

  10. Timing of tensor and levator veli palatini force application determines eustachian tube resistance patterns during the forced-response test.

    Science.gov (United States)

    Ghadiali, Samir N; Bell, E David; Swarts, J Douglas

    2010-12-01

    The forced-response test (FRT) is used to assess eustachian tube (ET) function in patients with middle ear disease (otitis media). This test often documents a dynamic pattern of luminal dilation and constriction during swallowing which can be quantified as a function relating active tubal resistance with time. The goal of this study is to use a generalized finite element model (FEM) to test the hypothesis that the relative timing of muscle force application by the tensor veli palatini muscle (mTVP) and levator veli palatini muscle (mLVP) on the ET determines the form of active resistance functions. Seven resistance waveforms were obtained during the FRT in five adult subjects. A 2D FEM of the ET was constructed from an adult histological specimen and viscoelastic tissue mechanical properties were specified based on measurements obtained in each subject. Least-squared regression routines were used to vary the timing and magnitude of mTVP and mLVP force applications to the ET in order to match the active resistance functions recorded during the FRT. Variation of muscle force timing and magnitude in the FEM simulations reproduced the seven active resistance waveforms with high fidelity. Early application of mTVP force in combination with mLVP force produced a waveform characterized by an initial dilation (low resistances) followed by lumen constriction (higher resistances), while delayed mTVP force application caused an initial lumen constriction followed by dilation. These results indicate that the active resistance waveforms observed during the FRT reflect differences in the temporal pattern of mLVP and mTVP force application to the ET and emphasize that, like the mTVP, the mLVP functionally interacts with the ET. Results also indicate that in normal adults contraction of the mLVP promotes lumen constriction and that the initial lumen constriction is highly sensitive to the relative delay timing of mTVP and mLVP force application. Copyright (c) 2010 Elsevier Ireland

  11. Real-Time Microscopic Monitoring of Flow, Voltage and Current in the Proton Exchange Membrane Water Electrolyzer.

    Science.gov (United States)

    Lee, Chi-Yuan; Li, Shih-Chun; Chen, Chia-Hung; Huang, Yen-Ting; Wang, Yu-Syuan

    2018-03-15

    Looking for alternative energy sources has been an inevitable trend since the oil crisis, and close attentioned has been paid to hydrogen energy. The proton exchange membrane (PEM) water electrolyzer is characterized by high energy efficiency, high yield, simple system and low operating temperature. The electrolyzer generates hydrogen from water free of any carbon sources (provided the electrons come from renewable sources such as solar and wind), so it is very clean and completely satisfies the environmental requirement. However, in long-term operation of the PEM water electrolyzer, the membrane material durability, catalyst corrosion and nonuniformity of local flow, voltage and current in the electrolyzer can influence the overall performance. It is difficult to measure the internal physical parameters of the PEM water electrolyzer, and the physical parameters are interrelated. Therefore, this study uses micro-electro-mechanical systems (MEMS) technology to develop a flexible integrated microsensor; internal multiple physical information is extracted to determine the optimal working parameters for the PEM water electrolyzer. The real operational data of local flow, voltage and current in the PEM water electrolyzer are measured simultaneously by the flexible integrated microsensor, so as to enhance the performance of the PEM water electrolyzer and to prolong the service life.

  12. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

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

  13. Biobased Membrane

    NARCIS (Netherlands)

    Koenders, E.A.B.; Zlopasa, J.; Picken, S.J.

    2015-01-01

    The present invention is in the field of a composition for forming a bio-compatible membrane applicable to building material, such as concrete, cement, etc., to a meth od of applying said composition for forming a bio-compatible membrane, a biocompatible membrane, use of said membrane for various

  14. Monitoring groundwater-surface water interaction using time-series and time-frequency analysis of transient three-dimensional electrical resistivity changes

    Science.gov (United States)

    Johnson, Timothy C.; Slater, Lee D.; Ntarlagiannis, Dimitris; Day-Lewis, Frederick D.; Elwaseif, Mehrez

    2012-01-01

    Time-lapse resistivity imaging is increasingly used to monitor hydrologic processes. Compared to conventional hydrologic measurements, surface time-lapse resistivity provides superior spatial coverage in two or three dimensions, potentially high-resolution information in time, and information in the absence of wells. However, interpretation of time-lapse electrical tomograms is complicated by the ever-increasing size and complexity of long-term, three-dimensional (3-D) time series conductivity data sets. Here we use 3-D surface time-lapse electrical imaging to monitor subsurface electrical conductivity variations associated with stage-driven groundwater-surface water interactions along a stretch of the Columbia River adjacent to the Hanford 300 near Richland, Washington, USA. We reduce the resulting 3-D conductivity time series using both time-series and time-frequency analyses to isolate a paleochannel causing enhanced groundwater-surface water interactions. Correlation analysis on the time-lapse imaging results concisely represents enhanced groundwater-surface water interactions within the paleochannel, and provides information concerning groundwater flow velocities. Time-frequency analysis using the Stockwell (S) transform provides additional information by identifying the stage periodicities driving groundwater-surface water interactions due to upstream dam operations, and identifying segments in time-frequency space when these interactions are most active. These results provide new insight into the distribution and timing of river water intrusion into the Hanford 300 Area, which has a governing influence on the behavior of a uranium plume left over from historical nuclear fuel processing operations.

  15. Hydrogen-1 NMR relaxation time studies in membrane: anesthetic systems; Variacao dos tempos de relaxacao longitudinal de protons em sistemas membranares contendo anestesicos locais

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, L.M.A.; Fraceto, L.; Paula, E. de [Universidade Estadual de Campinas, SP (Brazil). Dept. de Bioquimica; Franzoni, L.; Spisni, A. [Universita degli Studi di Parma, Parma (Italy). Ist. di Chimica Biologica

    1997-12-31

    The study of local anesthetics`(LA) interaction with model phospholipid membranes is justified by the direct correlation between anesthetic`s hydrophobicity and its potency/toxicity. By the same reason, uncharged LA species seems to play a crucial role in anesthesia. Most clinically used LA are small amphiphilics with a protonated amine group (pKa around 8). Although both charged (protonated) and uncharged forms can coexist at physiological pH, it has been shown (Lee, Biochim. Biophys. Acta 514:95, 1978; Screier et al. Biochim. Biophys. Acta 769:231, 1984) that the real anesthetic pka can be down-shifted, due to differential partition into membranes, increasing the ratio of uncharged species at pH 7.4. We have measured {sup 1}H-NMR longitudinal relaxation times (T{sub 1}) for phospholipid and three local anesthetics (tetracaine, lidocaine, benzocaine), in sonicated vesicles at a 3:1 molar ratio. All the LA protons have shown smaller T{sub 1} in this system than in isotropic phases, reflecting LA immobilization caused by insertion in the membrane. T{sub 1} values for the lipid protons in the presence of LA were analyzed, in an attempt to identify specific LA:lipid contact regions. (author) 13 refs., 3 figs., 1 tabs.

  16. Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Vatanpour, Vahid, E-mail: vahidvatanpour@khu.ac.ir; Zoqi, Naser

    2017-02-28

    Highlights: • A commercial PA RO membrane was modified by grafting of hydrophilic acrylic acid. • COOH-MWCNTs were mixed in grafting layer to increase permeability and antifouling. • However, more increase of CNTs caused in reduction of flux of the membranes. • Effect of acrylic acid amount, contact time and curing time was optimized. - Abstract: In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the

  17. Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

    Directory of Open Access Journals (Sweden)

    V. Romero

    2012-01-01

    A study of time evolution of the impedance curves measured in the system “IL aqueous solution/Nafion-112 membrane/IL aqueous solution” was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA+ hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

  18. Development of a real-time resistance measurement for Vibrio parahaemolyticus detection by the lecithin-dependent hemolysin gene.

    Directory of Open Access Journals (Sweden)

    Guiming Xiang

    Full Text Available The marine bacterium Vibrio parahaemolyticus (V. parahaemolyticus causes gastroenteritis in humans via the ingestion of raw or undercooked contaminated seafood, and early diagnosis and prompt treatment are important for the prevention of V. parahaemolyticus-related diseases. In this study, a real-time resistance measurement based on loop-mediated isothermal amplification (LAMP, electrochemical ion bonding (Crystal violet and Mg(2+, real-time monitoring, and derivative analysis was developed. V. parahaemolyticus DNA was first amplified by LAMP, and the products (DNA and pyrophosphate represented two types of negative ions that could combine with a positive dye (Crystal violet and positive ions (Mg(2+ to increase the resistance of the reaction liquid. This resistance was measured in real-time using a specially designed resistance electrode, thus permitting the quantitative detection of V. parahaemolyticus. The results were obtained in 1-2 hours, with a minimum bacterial density of 10 CFU.mL(-1 and high levels of accuracy (97%, sensitivity (96.08%, and specificity (97.96% when compared to cultivation methods. Therefore, this simple and rapid method has a potential application in the detection of V. parahaemolyticus on a gene chip or in point-of-care testing.

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

    Science.gov (United States)

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

    2015-08-01

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

  20. Imaging subsurface migration of dissolved CO2 in a shallow aquifer using 3-D time-lapse electrical resistivity tomography

    DEFF Research Database (Denmark)

    Auken, Esben; Doetsch, Joseph; Fiandaca, Gianluca

    2014-01-01

    Contamination of groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment in western Denmark, we investigate to what extent surface electrical resistivity tomography (ERT) can detect and image dissolved CO2 in a shallow aquifer. For this purpose...... of aeolian and glacial sands near the surface and marine sands below 10m depth. 3-D time-lapse ERT inversions clearly image the dissolved CO2 plume with decreased electrical resistivity values. We can image the geochemical changes induced by the dissolved CO2 until the end of the acquisition, 120days after......-intrusive surface electrical resistivity tomography. © 2013 Elsevier B.V....

  1. Analog memory and spike-timing-dependent plasticity characteristics of a nanoscale titanium oxide bilayer resistive switching device

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Kyungah; Park, Sangsu; Lee, Kwanghee; Lee, Byounghun; Hwang, Hyunsang [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kim, Insung; Jung, Seungjae; Jo, Minseok; Park, Jubong; Shin, Jungho; Biju, Kuyyadi P; Kong, Jaemin, E-mail: kyseo@gist.ac.kr, E-mail: hwanghs@gist.ac.kr [School of Material Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2011-06-24

    We demonstrated analog memory, synaptic plasticity, and a spike-timing-dependent plasticity (STDP) function with a nanoscale titanium oxide bilayer resistive switching device with a simple fabrication process and good yield uniformity. We confirmed the multilevel conductance and analog memory characteristics as well as the uniformity and separated states for the accuracy of conductance change. Finally, STDP and a biological triple model were analyzed to demonstrate the potential of titanium oxide bilayer resistive switching device as synapses in neuromorphic devices. By developing a simple resistive switching device that can emulate a synaptic function, the unique characteristics of synapses in the brain, e.g. combined memory and computing in one synapse and adaptation to the outside environment, were successfully demonstrated in a solid state device.

  2. Unit membrane parameters of electrically syncytial tissues.

    Science.gov (United States)

    Levin, D N

    1981-07-01

    A change in the holding voltage, exposure to channel-blocking agents, and similar interventions will induce changes in the membrane properties of electrically syncytial tissues. The altered membrane characteristics will produce changes in the input resistance (RIN) and the phase angle (phi) of the complex admittance of the whole preparation. Exact geometry-independent formulas are derived that give the intervention-induced changes in the membrane capacitance and conductance in terms of the measured changes in RIN and phi. The formulas automatically account for the effects of extracellular resistance in tissues such as skeletal muscle fibers, cardiac Purkinje fibers, and small cardiac "aggregates." The size, shape, and resistance of the extracellular space may be arbitrary and need not be measured. The surface (invaginated) membranes, which face the bath (extracellular space), are assumed to be characterized by an RC circuit with specific capacity Cme (Cmi) and specific conductivity gme (gmi). It is assumed that the intracellular voltage gradient between the electrodes and the membranes is negligible or reliably calculable. The intervention is assumed to leave the geometry and resistivity of the extracellular space unchanged. Under these circumstances the intervention-induced changes in Cme, Cmi, gme, and gmi are determined exactly in terms of the corresponding changes in RIN and certain frequency domain integrals over phi. The technique is illustrated by synthetic data for RIN and phi generated by the "disk" model of a skeletal muscle fiber in which Cme and Cmi depend upon holding voltage. The corresponding voltage dependence of RIN and phi is successfully "inverted" to expose the underlying voltage dependence of Cme and Cmi. These computations suggest that the formulas for Cme and Cmi will be useful in realistic situations, since they are not too sensitive to experimental error in the data for RIN and phi. This method makes it possible to detect voltage

  3. Development of a real-time PCR melt curve assay for simultaneous detection of virulent and antibiotic resistant Salmonella.

    Science.gov (United States)

    Singh, Prashant; Mustapha, Azlin

    2014-12-01

    Multiple drug resistance in Salmonella is an emerging problem in the area of food safety. Depending on the virulence and antibiotic resistance characteristics of the Salmonella strain, infections of varying severity could result. In this study, a multiplex melt curve real-time PCR assay for the detection of virulent and antibiotic resistance strains of Salmonella was developed with two primer sets. The first set targets the virulence gene, invasin (invA), and tetracycline (tetG), streptomycin (aadA2) and sulphonamide (sulI) antibiotic resistance genes, and the second set amplifies ampicillin (blaPSE,blaTEM) and chloramphenicol (floR) resistance genes. The multiplex assay was evaluated using 41 Salmonella strains and was further tested on eight different artificially inoculated food samples. The fluorescent DNA intercalating dye, SYTO9, generated high resolution melt curve peaks and, hence, was used for the development of the assay. This multiplex assay worked efficiently over a DNA concentration range of 20 ng-200 fg and showed a sensitivity of 290 CFU/mL with serially diluted broth cultures. The detection limit for un-enriched artificially inoculated food samples was 10(4) CFU/g, but an enrichment period of 6 h allowed for detection of 10 CFU/g of cells in the samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Colistin and doripenem combinations against Pseudomonas aeruginosa: profiling the time course of synergistic killing and prevention of resistance

    Science.gov (United States)

    Ly, Neang S.; Bulitta, Jürgen B.; Rao, Gauri G.; Landersdorfer, Cornelia B.; Holden, Patricia N.; Forrest, Alan; Bergen, Phillip J.; Nation, Roger L.; Li, Jian; Tsuji, Brian T.

    2015-01-01

    Objectives Colistin is an ‘old’ drug, which is being increasingly utilized due to limited therapeutic options. However, resistance emergence during monotherapy is concerning. Here, our objective was to optimize colistin combinations against Pseudomonas aeruginosa by profiling the time course of synergistic killing and prevention of resistance. Methods Hollow-fibre infection models over 10 days simulated clinically relevant dosage regimens of colistin and doripenem against two heteroresistant P. aeruginosa strains (MIC 1 mg/L) and one resistant (MIC 128 mg/L) strain (inoculum 109.3 cfu/mL). New mathematical mechanism-based models (MBMs) were developed using S-ADAPT. Results Against heteroresistant P. aeruginosa strains, colistin monotherapy resulted in initial killing (up to 2.64 log10 cfu/mL) within 24 h followed by regrowth. High-intensity combinations involving free steady-state colistin concentrations of 5 mg/L achieved complete eradication (>9.3 log10 killing) within 48 h. These combinations achieved synergy with up to 9.38 log10 greater killing compared with the most active monotherapy. Against the colistin-resistant strain, the combination yielded marked initial synergy with up to 6.11 log10 cfu/mL bacterial reductions within 72 h followed by regrowth. The MBMs quantified total and resistant subpopulations and the proposed synergy between colistin and doripenem. Conclusions Our findings provide insight into optimal antibiotic treatment and may serve as a framework for new drug combinations and combination modelling. PMID:25712313

  5. The Limits of International Adjudication: Authority and Resistance of Regional Economic Courts in Times of Crisis

    DEFF Research Database (Denmark)

    Caserta, Salvatore; Cebulak, Pola

    2018-01-01

    The article compares the involvement of four regional economic courts in legal disputes mirroring constitutional, political and social crises at national or regional level. These four judicial bodies of the European Union, the Andean Community, the East African Community and the Central American...... Integration System have all faced varied forms of resistance to their involvement and their general authority. By comparing these four case studies from across the globe, the article identifies institutional and contextual factors that explain the uneven resistance. While the regional economic courts...

  6. Effects of plasma treatment time on surface characteristics of indium-tin-oxide film for resistive switching storage applications

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Po-Hsun [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Chang, Ting-Chang, E-mail: tcchang3708@gmail.com [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Chang, Kuan-Chang, E-mail: kcchang@pkusz.edu.cn [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); School of Electronic and Computer Engineering, Peking University, Shenzhen 518055 (China); Tsai, Tsung-Ming; Pan, Chih-Hung; Shih, Chih-Cheng; Wu, Cheng-Hsien; Yang, Chih-Cheng; Chen, Wen-Chung; Lin, Jiun-Chiu; Wang, Ming-Hui [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Zheng, Hao-Xuan; Chen, Min-Chen [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Sze, Simon M. [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 300, Taiwan, ROC (China)

    2017-08-31

    In this paper, we implement a post-oxidation method to modify surface characteristics of indium tin oxide (ITO) films by using an O{sub 2} inductively coupled plasma (ICP) treatment. Based on field emission-scanning electron microscope (FE-SEM) and atomic force microscope (AFM) analysis, we found that the surface morphologies of the ITO films become slightly flatter after the O{sub 2} plasma treatment. The optical characteristics and X-ray diffraction (XRD) experiments of either pure ITO or O{sub 2} plasma treated ITO films were also verified. Even though the XRD results showed no difference from bulk crystallizations, the oxygen concentrations increased at the film surface after O{sub 2} plasma treatment, according to the XPS inspection results. Moreover, this study investigated the effects of two different plasma treatment times on oxygen concentration in the ITO films. The surface sheet resistance of the plasma treated ITO films became nearly non-conductive when measured with a 4-point probe. Finally, we applied the O{sub 2} plasma treated ITO films as the insulator in resistive random access memory (RRAM) to examine their potential for use in resistive switching storage applications. Stable resistance switching characteristics were obtained by applying the O{sub 2} plasma treatment to the ITO-based RRAM. We also confirmed the relationship between plasma treatment time and RRAM performance. These material analyses and electrical measurements suggest possible advantages in using this plasma treatment technique in device fabrication processes for RRAM applications.

  7. Comparison of HIV-1 genotypic resistance test interpretation systems in predicting virological outcomes over time

    NARCIS (Netherlands)

    D. Frentz (Dineke); C.A.B. Boucher (Charles); M. Assel (Matthias); A. de Luca (Andrea); M. Fabbiani (Massimiliano); F. Incardona (Francesca); P. Libin (Pieter); N. Manca (Nino); V. Müller (Viktor); B.O. Nualláin (Breanndán); R. Paredes (Roger); M. Prosperi (Mattia); E. Quiros-Roldan (Eugenia); L. Ruiz (Lidia); P.M.A. Sloot (Peter); C. Torti (Carlo); A.M. Vandamme (Anne Mieke); K. Laethem (Kristel); M. Zazzi (Maurizio); D.A.M.C. van de Vijver (David)

    2010-01-01

    textabstractBackground: Several decision support systems have been developed to interpret HIV-1 drug resistance genotyping results. This study compares the ability of the most commonly used systems (ANRS, Rega, and Stanford's HIVdb) to predict virological outcome at 12, 24, and 48 weeks.

  8. Fluoroquinolone resistance detection in Mycobacterium tuberculosis with locked nucleic acid probe real-time PCR

    NARCIS (Netherlands)

    van Doorn, H. R.; An, D. D.; de Jong, M. D.; Lan, N. T. N.; Hoa, D. V.; Quy, H. T.; Chau, N. V. V.; Duy, P. M.; Tho, D. Q.; Chinh, N. T.; Farrar, J. J.; Caws, M.

    2008-01-01

    SETTING: Pham Ngoc Thach Hospital for Tuberculosis and Lung Diseases, Ho Chi Minh City, Vietnam. OBJECTIVE: Fluoroquinolones (FQs) are increasingly used in the treatment of tuberculosis (TB) and are the second-line drugs of choice for treatment of multidrug-resistant TB. We aimed to set up a

  9. Effect of manure application rate and timing on the leaching potential of antibiotic resistant bacteria.

    Science.gov (United States)

    Antibiotics are used in swine production for therapeutic and growth promotion purposes. Because land application is the most common method of disposing of swine lagoon effluent, there exists the potential threat of contaminating the underlying groundwater with antimicrobial-resistant bacteria (ARB) ...

  10. Probing Growth-Induced Anisotropic Thermal Transport in High-Quality CVD Diamond Membranes by Multifrequency and Multiple-Spot-Size Time-Domain Thermoreflectance.

    Science.gov (United States)

    Cheng, Zhe; Bougher, Thomas; Bai, Tingyu; Wang, Steven Y; Li, Chao; Yates, Luke; Foley, Brian M; Goorsky, Mark; Cola, Baratunde A; Faili, Firooz; Graham, Samuel

    2018-02-07

    The maximum output power of GaN-based high-electron mobility transistors is limited by high channel temperature induced by localized self-heating, which degrades device performance and reliability. Chemical vapor deposition (CVD) diamond is an attractive candidate to aid in the extraction of this heat and in minimizing the peak operating temperatures of high-power electronics. Owing to its inhomogeneous structure, the thermal conductivity of CVD diamond varies along the growth direction and can differ between the in-plane and out-of-plane directions, resulting in a complex three-dimensional (3D) distribution. Depending on the thickness of the diamond and size of the electronic device, this 3D distribution may impact the effectiveness of CVD diamond in device thermal management. In this work, time-domain thermoreflectance is used to measure the anisotropic thermal conductivity of an 11.8 μm-thick high-quality CVD diamond membrane from its nucleation side. Starting with a spot-size diameter larger than the thickness of the membrane, measurements are made at various modulation frequencies from 1.2 to 11.6 MHz to tune the heat penetration depth and sample the variation in thermal conductivity. We then analyze the data by creating a model with the membrane divided into ten sublayers and assume isotropic thermal conductivity in each sublayer. From this, we observe a two-dimensional gradient of the depth-dependent thermal conductivity for this membrane. The local thermal conductivity goes beyond 1000 W/(m K) when the distance from the nucleation interface only reaches 3 μm. Additionally, by measuring the same region with a smaller spot size at multiple frequencies, the in-plane and cross-plane thermal conductivities are extracted. Through this use of multiple spot sizes and modulation frequencies, the 3D anisotropic thermal conductivity of CVD diamond membrane is experimentally obtained by fitting the experimental data to a thermal model. This work provides an improved

  11. Performance evaluation and mass transfer study of CO{sub 2} absorption in flat sheet membrane contactor using novel porous polysulfone membrane

    Energy Technology Data Exchange (ETDEWEB)

    Nabian, Nima; Ghoreyshi, Ali Asghar; Rahimpour, Ahmad; Shakeri, Mohsen [Babol University of Technology, Babol (Iran, Islamic Republic of)

    2015-11-15

    The performance of gas-liquid membrane contactor for CO{sub 2} capture was investigated using a novel polysulfone (PSF) flat membrane prepared via non-solvent phase inversion method. Polyvinyl pyrrolidone (PVP) was used as an additive in the dope solution of PSF membranes. Morphological studies by scanning electron microscopy (SEM) analysis revealed that PSF membrane with PVP has a finger-like structure, but the PSF membrane without PVP has a sponge-like structure. Also, characterization results through atomic force microscopy (AFM) and contact angle measurement demonstrated that the porosity, surface roughness and hydrophobicity of the PSF membrane increased with addition of PVP to the dope solution. Mass transfer resistance analysis, based on CO{sub 2} absorption flux, displayed that addition of PVP to the dope solution of PSF membrane decreased membrane mass transfer resistance, and significantly improved CO{sub 2} absorption flux up to 2.7 and 1.8 times of absorption fluxes of PSF membrane without PVP and commercial PVDF, respectively.

  12. Metabolomic profiling of Campylobacter jejuni with resistance gene ermB by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry and tandem quadrupole mass spectrometry.

    Science.gov (United States)

    Fu, Qin; Liu, Dejun; Wang, Yingyu; Li, Xiaowei; Wang, Lina; Yu, Fugen; Shen, Jianzhong; Xia, Xi

    2018-03-15

    The metabolome changes of Campylobacter jejuni with resistant gene ermB remain unclear. Here, we described an untargeted metabolomic workflow based on ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry to investigate the metabolites perturbations mediated by ermB in C. jejuni. After optimization of extractants and chromatographic conditions, the combination of 100% methanol extraction with a 12 min gradient by C18 column was adopted for untargeted metabolomic profiling in reversed phase separation. Meanwhile, 60% methanol extraction followed by a 14 min separation using hydrophilic interaction chromatography column was suitable to complementally expand the metabolite coverage of C. jejuni. Multivariate statistical analysis was performed by means of orthogonal projection to latent structures-discriminant analysis to select metabolic features. The selected features were further confirmed by ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry. A total of thirty-six differential metabolites between the susceptible strain (C. jejuni NCTC 11168) and resistant stain (C. jejuni NCTC 11168 with ermB) were identified. These pivotal metabolites were primarily participated in biological processes as cell signaling, membrane integrity/stability, fuel and energy source/storage and nutrient. The biofilm formation capability of resistant strain was inferior to that of susceptible strain, confirming the influence of ermB on membrane integrity/stability of C. jejuni. Our findings revealed important metabolic regulatory pathways associated with resistant C. jejuni with ermB. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Time-series analysis in imatinib-resistant chronic myeloid leukemia K562-cells under different drug treatments.

    Science.gov (United States)

    Zhao, Yan-Hong; Zhang, Xue-Fang; Zhao, Yan-Qiu; Bai, Fan; Qin, Fan; Sun, Jing; Dong, Ying

    2017-08-01

    Chronic myeloid leukemia (CML) is characterized by the accumulation of active BCR-ABL protein. Imatinib is the first-line treatment of CML; however, many patients are resistant to this drug. In this study, we aimed to compare the differences in expression patterns and functions of time-series genes in imatinib-resistant CML cells under different drug treatments. GSE24946 was downloaded from the GEO database, which included 17 samples of K562-r cells with (n=12) or without drug administration (n=5). Three drug treatment groups were considered for this study: arsenic trioxide (ATO), AMN107, and ATO+AMN107. Each group had one sample at each time point (3, 12, 24, and 48 h). Time-series genes with a ratio of standard deviation/average (coefficient of variation) >0.15 were screened, and their expression patterns were revealed based on Short Time-series Expression Miner (STEM). Then, the functional enrichment analysis of time-series genes in each group was performed using DAVID, and the genes enriched in the top ten functional categories were extracted to detect their expression patterns. Different time-series genes were identified in the three groups, and most of them were enriched in the ribosome and oxidative phosphorylation pathways. Time-series genes in the three treatment groups had different expression patterns and functions. Time-series genes in the ATO group (e.g. CCNA2 and DAB2) were significantly associated with cell adhesion, those in the AMN107 group were related to cellular carbohydrate metabolic process, while those in the ATO+AMN107 group (e.g. AP2M1) were significantly related to cell proliferation and antigen processing. In imatinib-resistant CML cells, ATO could influence genes related to cell adhesion, AMN107 might affect genes involved in cellular carbohydrate metabolism, and the combination therapy might regulate genes involved in cell proliferation.

  14. Mapping geological structures in bedrock via large-scale direct current resistivity and time-domain induced polarization tomography

    DEFF Research Database (Denmark)

    Rossi, Matteo; Olsson, Per-Ivar; Johansson, Sara

    2017-01-01

    An investigation of geological conditions is always a key point for planning infrastructure constructions. Bedrock surface and rock quality must be estimated carefully in the designing process of infrastructures. A large direct-current resistivity and time-domain induced-polarization survey has b...... been performed in Dalby, Lund Municipality, southern Sweden, with the aim of mapping lithological variations in bedrock. The geology at the site is characterised by Precambrian granitic gneisses and amphibolites, which are intensely deformed, fractured, and partly weathered. In addition......-polarization profiles. The direct-current resistivity and time-domain induced-polarization methodology proved to be a suitable technique for extensively mapping weathered zones with poor geotechnical characteristics and tectonic structures, which can lead to severe problems for infrastructure construction and....../or constitute risk zones for aquifer contamination....

  15. 13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    The purpose of the present study was to examine the short-term effect of dietary specific structured triacylglycerols (MLM, M = 8:0, L = 18:2n-6), LLL and MMM on the fatty acid composition of brush border membrane (BBM) phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Rats were...... administered intragastrically a bolus of ML*M, M*LM*, L*L*L* or M*M*M* (* = C-13- labeled fatty acid). Rats were decapitated 2 hours and 6 hours later, and the fatty acid composition and C-13-enrichment of BBM-PC and -PE were determined. C-13-enriched 18:2n-6 was observed in BBM-PC after intragastric...... administration of L*L*L* and ML*M, whereas no C-13-labeled fatty acids were recovered after administration of M*LM* or M*M*M*. Interestingly, no C-13-labeled fatty acids were detected in the BBM-PE fraction. This could be due to a lower turnover of PE than PC and to a different ratio of saturated and unsaturated...

  16. Determination of the mean transit time for the transport of aerosolized 99mTc-DTPA across the pulmonary epithelial membrane. A plasma sample method

    DEFF Research Database (Denmark)

    Groth, Sofie; Lassen, N A; Rossing, Niels Nygaard

    1988-01-01

    During the last decade it has been customary to estimate pulmonary epithelial permeability (P-P) as the pulmonary clearance of inhaled nebulized 99mTc-DTPA from a time-activity (t-a) curve registered externally by monitoring over the chest. The t-a curve, however, is not defined by the degree of P......-P alone but also by factors such as the deposition of the 99mTc-DTPA in the lungs. To avoid these problems a plasma sample method was derived. It describes P-P by the mean transit time (t) for the transport of 99mTc-DTPA across the pulmonary epithelial membrane, t(L). The calculation of t(L) involves two...... steps. Following the inhalation of Tc-DTPA the plasma t-a curve is defined and used to calculate t for the transport for 99mTc-DTPA across the pulmonary epithelial membrane, through the ECV and until elimination by the kidneys, t(L+ECV). Subsequently, 99mTc-DTPA is injected as a bolus i.v. and the new t...

  17. Lu-177-PSMA-617 Prostate-Specific Membrane Antigen Inhibitor Therapy in Patients with Castration-Resistant Prostate Cancer: Stability, Bio-distribution and Dosimetry

    Directory of Open Access Journals (Sweden)

    Levent Kabasakal

    2017-06-01

    Full Text Available Objective: The aim of the study was to estimate the radiation-absorbed doses and to study the in vivo and in vitro stability as well as pharmacokinetic characteristics of lutetium-177 (Lu-177 prostate-specific membrane antigen (PSMA-617. Methods: For this purpose, 7 patients who underwent Lu-177-PSMA therapy were included into the study. The injected Lu-177-PSMA-617 activity ranged from 3.6 to 7.4 GBq with a mean of 5.2±1.8 GBq. The stability of radiotracer in saline was calculated up to 48 h. The stability was also calculated in blood and urine samples. Post-therapeutic dosimetry was performed based on whole body and single photon emission computed tomography/computed tomography (SPECT/CT scans on dual-headed SPECT/CT system. Results: The radiochemical yield of Lu-177-PSMA-617 was >99%. It remained stable in saline up to 48 h. Analyses of the blood and urine samples showed a single radioactivity peak even at 24 hours after injection. Half-life of the distribution and elimination phases were calculated to be 0.16±0.09 and 10.8±2.5 hours, respectively. The mean excretion rate was 56.5±8.8% ranging from 41.5% to 65.4% at 24 h. Highest radiation estimated doses were calculated for parotid glands and kidneys (1.90±1.19 and 0.82±0.25 Gy/GBq respectively. Radiation dose given to the bone marrow was significantly lower than those of kidney and parotid glands (p<0.05 (0.030±0.008 Gy/GBq. Conclusion: Lu-177-PSMA-617 is a highly stable compound both in vitro and in vivo. Lu-177-PSMA-617 therapy seems to be a safe method for the treatment of castration-resistant prostate cancer patients. The fractionation regime that enables the longest duration of tumor control and/or survival will have to be developed in further studies.

  18. Dose- and time-dependent effects of actomyosin inhibition on live mouse outflow resistance and aqueous drainage tissues.

    Science.gov (United States)

    Ko, MinHee K; Kim, Eun Kyoung; Gonzalez, Jose M; Tan, James C

    2016-02-17

    Actomyosin contractility modulates outflow resistance of the aqueous drainage tissues and intraocular pressure, a key pathogenic factor of glaucoma. We established methodology to reliably analyze the effect of latrunculin-B (Lat-B)-induced actin depolymerization on outflow physiology in live mice. A voltage-controlled microperfusion system for delivering drugs and simultaneously analyzing outflow resistance was tested in live C57BL/6 mice. Flow rate and perfusion pressure were reproducible within a coefficient of variation of 2%. Outflow facility for phosphate-buffered saline (0.0027 ± 0.00036 μL/min/mmHg; mean ± SD) and 0.02% ethanol perfusions (Lat-B vehicle; 0.0023 ± 0.0005 μL/min/mmHg) were similar and stable over 2 hours (p > 0.1 for change), indicating absence of a 'washout' artifact seen in larger mammals. Outflow resistance changed in graded fashion, decreasing dose- and time-dependently over 2 hours for Lat-B doses of 2.5 μM (p = 0.29), 5 μM (p = 0.039) and 10 μM (p = 0.001). Resulting outflow resistance was about 10 times lower with 10 μM Lat-B than vehicle control. The filamentous actin network was decreased and structurally altered in the ciliary muscle (46 ± 5.6%) and trabecular meshwork (37 ± 8.3%) of treated eyes relative to vehicle controls (p < 0.005; 5 μM Lat-B). Mouse actomyosin contractile mechanisms are important to modulating aqueous outflow resistance, mirroring mechanisms in primates. We describe approaches to reliably probe these mechanisms in vivo.

  19. A field-portable membrane introduction mass spectrometer for real-time quantitation and spatial mapping of atmospheric and aqueous contaminants.

    Science.gov (United States)

    Bell, Ryan J; Davey, Nicholas G; Martinsen, Morten; Collin-Hansen, Christian; Krogh, Erik T; Gill, Christopher G

    2015-02-01

    Environmental concentrations of volatile and semivolatile organic compounds (VOC/SVOCs) can vary dramatically in time and space under the influence of environmental conditions. In an industrial setting, multiple point and diffuse sources can contribute to fugitive emissions. Assessments and monitoring programs using periodic grab sampling provide limited information, often with delay times of days or weeks. We report the development and use of a novel, portable membrane introduction mass spectrometry (MIMS) system capable of resolving and quantifying VOC and SVOCs with high spatial and temporal resolution, in the field, in real-time. An electron impact ionization cylindrical ion trap mass spectrometer modified with a capillary hollow fiber polydimethylsiloxane membrane interface was used for continuous air and water sampling. Tandem mass spectrometry and selected ion monitoring scans performed in series allowed for the quantitation of target analytes, and full scan mode was used to survey for unexpected analytes. Predeployment and in-field external calibrations were combined with a continuously infused internal standard to enable real-time quantitation and monitor instrument performance. The system was operated in a moving vehicle with internet-linked data processing and storage. Software development to integrate MIMS and relevant meta-data for visualization and geospatial presentation in Google Earth is presented. Continuous quantitation enables the capture of transient events that may be missed or under-represented by traditional grab sampling strategies. Real-time geospatial maps of chemical concentration enable adaptive sampling and in-field decision support. Sample datasets presented in this work were collected in Northern Alberta in 2010-2012.

  20. A Field-Portable Membrane Introduction Mass Spectrometer for Real-time Quantitation and Spatial Mapping of Atmospheric and Aqueous Contaminants

    Science.gov (United States)

    Bell, Ryan J.; Davey, Nicholas G.; Martinsen, Morten; Collin-Hansen, Christian; Krogh, Erik T.; Gill, Christopher G.

    2015-02-01

    Environmental concentrations of volatile and semivolatile organic compounds (VOC/SVOCs) can vary dramatically in time and space under the influence of environmental conditions. In an industrial setting, multiple point and diffuse sources can contribute to fugitive emissions. Assessments and monitoring programs using periodic grab sampling provide limited information, often with delay times of days or weeks. We report the development and use of a novel, portable membrane introduction mass spectrometry (MIMS) system capable of resolving and quantifying VOC and SVOCs with high spatial and temporal resolution, in the field, in real-time. An electron impact ionization cylindrical ion trap mass spectrometer modified with a capillary hollow fiber polydimethylsiloxane membrane interface was used for continuous air and water sampling. Tandem mass spectrometry and selected ion monitoring scans performed in series allowed for the quantitation of target analytes, and full scan mode was used to survey for unexpected analytes. Predeployment and in-field external calibrations were combined with a continuously infused internal standard to enable real-time quantitation and monitor instrument performance. The system was operated in a moving vehicle with internet-linked data processing and storage. Software development to integrate MIMS and relevant meta-data for visualization and geospatial presentation in Google Earth is presented. Continuous quantitation enables the capture of transient events that may be missed or under-represented by traditional grab sampling strategies. Real-time geospatial maps of chemical concentration enable adaptive sampling and in-field decision support. Sample datasets presented in this work were collected in Northern Alberta in 2010-2012.

  1. Membranous nephropathy

    Science.gov (United States)

    ... check for hepatitis B, hepatitis C, and syphilis Complement levels Cryoglobulin test Treatment The goal of treatment ... not as helpful for people with membranous nephropathy. Medicines used treat membranous nephropathy include: Angiotensin-converting enzyme ( ...

  2. ATP-binding cassette transporters are enriched in non-caveolar detergent-insoluble glycosphingolipid-enriched membrane domains (DIGs) in human multidrug-resistant cancer cells

    NARCIS (Netherlands)

    Hinrichs, JWJ; Klappe, K; Hummel, [No Value; Kok, JW

    2004-01-01

    In this study we show that P-glycoprotein in multi-drug-resistant 2780AD human ovarian carcinoma cells and multidrug resistance-associated protein 1 in multi-drug-resistant HT29(col) human colon carcinoma cells are predominantly located in Lubrol-based detergent-insoluble glycosphingolipid-enriched

  3. Polypyrrole layered SPEES/TPA proton exchange membrane for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Neelakandan, S.; Kanagaraj, P. [PG & Research Department of Chemistry, Polymeric Materials Research Lab, Alagappa Government Arts College, Karaikudi 630003 (India); Sabarathinam, R.M. [Functional Material Division, Central Electrochemical Research Institute, Karaikudi 630006 (India); Nagendran, A., E-mail: nagimmm@yahoo.com [PG & Research Department of Chemistry, Polymeric Materials Research Lab, Alagappa Government Arts College, Karaikudi 630003 (India)

    2015-12-30

    Graphical abstract: - Highlights: • A series of Ppy layered SPEES/TPA composite membranes were prepared. • SPEES/TPA-Ppy hybrid membranes displayed efficient methanol resistance than Nafion 117. • SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity of 2.86 × 104 S cm{sup 3} s. • Increasing Ppy layer on membrane surface reduces the leaching out of tungstophosphoric acid. - Abstract: Hybrid membranes based on sulfonated poly(1,4-phenylene ether ether sulfone) (SPEES)/tungstophosphoric acid (TPA) were prepared. SPEES/TPA membrane surfaces were modified with polypyrrole (Ppy) by in situ polymerization method to reduce the TPA leaching. The morphology and electrochemical property of the surface coated membranes were studied by SEM, AFM, water uptake, ion exchange capacity, proton conductivity, methanol permeability and tensile strength. The water uptake and the swelling ratio of the surface coated membranes decreased with increasing the Ppy layer. The surface roughness of the hybrid membrane was decreased with an increase in Ppy layer on the membrane surface. The methanol permeability of SPEES/TPA-Ppy4 hybrid membrane was significantly suppressed and found to be 2.1 × 10{sup −7} cm{sup 2} s{sup −1}, which is 1.9 times lower than pristine SPEES membrane. The SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity (2.86 × 10{sup 4} S cm{sup −3} s) than the other membrane with low TPA leaching. The tensile strength of hybrid membranes was improved with the introduction of Ppy layer. Combining their lower swelling ratio, high thermal stability and selectivity, SPEES/TPA-Ppy4 membranes could be a promising material as PEM for DMFC applications.

  4. Potent synergistic in vitro interaction between nonantimicrobial membrane-active compounds and itraconazole against clinical isolates of Aspergillus fumigatus resistant to itraconazole.

    NARCIS (Netherlands)

    Afeltra, J.; Vitale, R.G.; Mouton, J.W.; Verweij, P.E.

    2004-01-01

    To develop new approaches for the treatment of invasive infections caused by Aspergillus fumigatus, the in vitro interactions between itraconazole (ITZ) and seven different nonantimicrobial membrane-active compounds--amiodarone (AMD), amiloride, lidocaine, lansoprazole (LAN), nifedipine (NIF),

  5. Microencapsulation within crosslinked polyethyleneimine membranes.

    Science.gov (United States)

    Poncelet, D; Alexakis, T; Poncelet de Smet, B; Neufeld, R J

    1994-01-01

    A microencapsulation technique is proposed involving the formation of a polyethyleneimine (PEI) membrane crosslinked by an acid dichloride. The membranes were formed at pH 8 in a non-polar solvent, conditions which are better suited for the encapsulation of biocatalysts or fragile biochemicals than those using polyamide membranes. The mean diameter and size distribution of the PEI microcapsules were similar to that observed with nylon membranes. The resultant microcapsules were spherical, free-flowing with a strong membrane. The mass of membrane was seen to be independent of the reaction time (1-4 min), insensitive to the PEI concentration and proportional to the concentration of crosslinking agent.

  6. Transfer patterns of integron-associated and antibiotic resistance genes in S. flexneri during different time intervals in Tianjin, China

    Directory of Open Access Journals (Sweden)

    J Wang

    2014-01-01

    Full Text Available Background: Shigella is one of the common genera of pathogens responsible for bacterial diarrhoea in humans. According to World Health Organisation (WHO, 800,000-1,700,000 patients in China were infected with Shigella spp. in 2000, and Shigella flexneri is the most common serotype (86%. Objectives: We investigated the transfer patterns of integron-associated and antibiotic resistance genes in S. flexneri during different time intervals in the city of Tianjin in the People′s Republic of China. Materials and Methods: The integrase-encoding and variable regions of the integrons of the bacterial strains were amplified by polymerase chain reaction (PCR, followed by gene sequencing. Fifty-six S. flexneri strains, 32 of which were stored in our laboratory and the other 24 were isolated from tertiary hospitals in Tianjin during different time intervals, were tested for their sensitivity to 12 antibiotics by using the Kirby-Bauer antibiotic testing method (K-B method. Results and Conclusion: Of the 32 strains of S. flexneri isolated from 1981 to 1983 and stored in our laboratory, class 1 integron was detected in 28 strains (87.50%, while 27 strains (84.37% harboured an aminoglycoside resistance gene, aadA, in the variable region of their integrons. Class 1 integron was identified in 22 (91.67% of the 24 S. flexneri strains isolated from 2009 to 2010, whereas the variable region and 3′-end amplification were not present in any of the strains. Class 2 integron was not found in the 1981-1983 group (group A of strains; although 19 (79.17% of the 24 strains in the 2009-2010 group (group B possessed class 2 integron, and the variable region of the integron harboured dfrA1 + sat1 + aadA1 genes, which, respectively, mediate antibiotic resistance to trimethoprim, streptothricin and streptomycin. Seventeen strains of the total 56 possessed both class 1 and 2 integrons. Strains belonging to group A were highly resistant to tetracycline, chloramphenicol and a

  7. Contributions of IMP-10 metallo-beta-lactamase, the outer membrane barrier and the MexAB-OprM efflux system to high-level carbapenem resistance in Pseudomonas aeruginosa.

    Science.gov (United States)

    Zhao, Wei-Hua; Hu, Zhuting; Chen, Gelin; Ito, Ribu; Hu, Zhi-Qing

    2009-01-01

    The emergence of carbapenem-hydrolyzing metallo-beta-lactamases (MBLs) is a serious threat to clinical medication of carbapenems. We evaluated the contributions of IMP-10 MBL, the outer membrane barrier and the MexAB-OprM efflux system to high-level carbapenem resistance in Pseudomonas aeruginosa clinical isolates. MBL-producing strains were screened by ceftazidime and mercaptoacetic acid double-disk synergy testing. Genes were determined by PCR analysis and DNA sequencing. IMP-10 MBL activity was assayed using nitrocefin as a substrate. The bla(IMP-10)+ strains showed high-level resistance to carbapenems, with minimum inhibitory concentrations of 512 to >4,096 microg/ml. The minimum inhibitory concentrations were decreased by the inhibitors of MBLs, sodium mercaptoacetate (SMA) and ethylenediaminetetraacetic acid (EDTA), 16 and 64 fold, respectively. However, against the activity of the prepared IMP-10 MBL, the 50% inhibitory concentrations of SMA and EDTA were 5.5 and 211.6 microM, respectively, indicating that SMA was much more effective than EDTA in blocking the enzyme activity. The contradictory results may be explained by the additional effect of EDTA as an outer membrane permeabilizer because the susceptibility of the bla(IMP)- strains to carbapenems was increased 2 fold by EDTA, but not by SMA. In the presence of carbonyl cyanide M-chlorophenylhydrazone, a proton motive force inhibitor, the susceptibility of the P. aeruginosa isolates to carbapenems was increased 1-4 fold. The acquired IMP-10 MBL is a crucial factor in the high-level resistance to carbapenems in P. aeruginosa clinical isolates, while the outer membrane barrier and the MexAB-OprM efflux system play a basic and minor role, respectively. Copyright 2009 S. Karger AG, Basel.

  8. Effect of Heating Time to Density, Hardness, and Resistivity Againt Fungus of Yellow Bamboo (Bambusa Vulgaris Var Schard. Vitata)

    Science.gov (United States)

    Dawam Abdullah, A. H.; Nasution, Saukani

    2018-01-01

    It has been studied the influence of heating process to the density, hardness and resistivity againt fungus of Yellow bamboo (Bambusa Vulgaris Var Schard. Vitata). Structure of bamboo is identified by optical microscope. Bamboo is heated at 100 °C with variation of heating time: 0, 1, 2, 3 and 4 hours. Density of bamboo is measured by using pycnometer, whereas hardness is measured by using a Rockwell Hardness Type-R (HRR). Resistivity againt fungus is observed by naked eye. OM image shows that bamboo consist of hollow structures wherein the water is stored. The diameter of vascular at inner part (∼ 150 μm) is quite larger than outer part (∼50 μm). Heating time of one hour caused density decrease by about 39%, whereas heating four hours will decrease by 52%. The longer heating time, the hardness of bamboo is increased. For the longitudinal side, two hours heating increased hardness up to 31%. For tangential side, four hours heating time increased hardness until 82%. Furthermore, heating time 3-4 hours will persist bamboo from fungus attack more than 14 days.

  9. Photoresponsive nanostructured membranes

    KAUST Repository

    Madhavan, Poornima

    2016-07-26

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

  10. Composite membrane with integral rim

    Science.gov (United States)

    Routkevitch, Dmitri; Polyakov, Oleg G

    2015-01-27

    Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

  11. Membrane Biophysics

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2013-01-01

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

  12. Effects of fluoroquinolone restriction (from 2007 to 2012) on resistance in Enterobacteriaceae: interrupted time-series analysis.

    Science.gov (United States)

    Sarma, J B; Marshall, B; Cleeve, V; Tate, D; Oswald, T; Woolfrey, S

    2015-09-01

    Antibiotic stewardship is a key component in the effort to reduce healthcare-associated infections. To describe the implementation and analyse the impact of fluoroquinolone restriction on resistance in Enterobacteriaceae, focusing on urinary isolates of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli, which were historically almost universally resistant to fluoroquinolones. ESBL-producing E. coli hospital and community isolates, obtained between April 2009 and March 2012 from consecutive non-duplicate urine samples, were included in an interrupted time-series analysis based on a Poisson distribution model. Periods before and after fluoroquinolone restriction were compared. The trend in fluoroquinolone resistance in all urinary isolates of Enterobacteriaceae (N ≈ 20,000 per year) and blood culture isolates of E. coli (N ≈ 350) between 2009 and 2013 were also analysed. A large decline in the percentage of ciprofloxacin-resistant ESBL-producing urinary E. coli isolates was observed in both hospital (risk ratio: 0.473; 95% confidence interval: 0.315-0.712) and community settings (0.098; 0.062-0.157). The decline was also marked in all urinary isolates of Enterobacteriaceae and E. coli isolates from blood cultures. We conclude that reducing fluoroquinolone usage to a level of ≤2 defined daily doses per 100 occupied bed-days in hospital sufficiently removed selection pressure to allow resistant Enterobacteriaceae – specifically, the UK endemic strains of ESBL-producing E. coli – to revert back to fluoroquinolone susceptibility within a short span of four months. This was accompanied with a concomitant reduction in overall ESBL burden. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  13. The evolution of bacterial resistance against bacteriophages in the horse chestnut phyllosphere is general across both space and time

    Science.gov (United States)

    Koskella, Britt; Parr, Nicole

    2015-01-01

    Insight to the spatial and temporal scales of coevolution is key to predicting the outcome of host–parasite interactions and spread of disease. For bacteria infecting long-lived hosts, selection to overcome host defences is just one factor shaping the course of evolution; populations will also be competing with other microbial species and will themselves be facing infection by bacteriophage viruses. Here, we examine the temporal and spatial patterns of bacterial adaptation against natural phage populations from within leaves of horse chestnut trees. Using a