WorldWideScience

Sample records for bromide efflux kinetics

  1. Revisiting the Kinetics and Mechanism of Bromate-Bromide Reaction

    Directory of Open Access Journals (Sweden)

    Côrtes Carlos Eduardo S.

    2001-01-01

    Full Text Available The bromate-bromide reaction was investigated in an acidity range not studied yet. The reaction was followed at the Br2/Br3- isosbestic point (lambda = 446 nm. It was observed a first-order behavior for bromate and bromide ions and a second-order behavior for H+ ion that results in the rate law nu = k[BrO3-][Br- ][H+]². This rate law suggests a mechanism involving two successive protonation of bromate followed by the interaction of the intermediate species H2BrO3+ with bromide. These results disagree with the obtained by other authors who observed a second-order behavior for the bromide and first-order for H+, and have proposed intermediate species like H2Br2O3 and HBr2O3-. The second-order for [H+] observed in the range 0.005 <= [H+] <= 2.77 mol L-1 sets down that the pKa of bromic acid, HBrO3, must be lower than -0.5 (T = 25 °C, different from all other values for this pKa proposed in the literature.

  2. Kinetics adsorption study of the ethidium bromide by graphene oxide as adsorbent from aqueous matrices

    Science.gov (United States)

    Rajabi, M.; Moradi, O.; Zare, K.

    2017-01-01

    In this study of ethidium bromide, adsorption from aqueous matrices by graphene oxide as adsorbent was investigated. Influencing parameters in the adsorption study included contact time, temperature, and pH. The optimum time was selected 17 min, and the best value of pH was determined at 8. All adsorption experiments were performed at 298 K temperature. The maximum wavelength of ethidium bromide was 475 nm. The Elovich, four types of the pseudo-second-order, the pseudo-first-order, and intra-particle diffusion kinetic adsorption models were used for kinetic study, and the results show that adsorption of ethidium bromide on graphene oxide surface best complied with type (I) of the pseudo-second-order kinetic model.

  3. Kinetics of Chlorination of Benzophenone-3 in the Presence of Bromide and Ammonia.

    Science.gov (United States)

    Abdallah, Pamela; Deborde, Marie; Dossier Berne, Florence; Karpel Vel Leitner, Nathalie

    2015-12-15

    The aim of this study was to assess the impact of chlorination on the degradation of one of the most commonly used UV filters (benzophenone-3 (BP-3)) and the effects of bromide and ammonia on the kinetics of BP-3 elimination. Bromide and ammonia are rapidly converted to bromine and chloramines during chlorination. At first, the rate constants of chlorine, bromine and monochloramine with BP-3 were determined at various pH levels. BP-3 was found to react rapidly with chlorine and bromine, with values of apparent second order rate constants equal to 1.25(±0.14) × 10(3) M(-1)·s(-1) and 4.04(±0.54) × 10(6) M(-1)·s(-1) at pH 8.5 for kChlorine/BP-3 and kBromine/BP-3, respectively, whereas low monochloramine reactivity was observed (kNH2Cl/BP-3 = 0.112 M(-1)·s(-1)). To assess the impact of the inorganic content of water on BP-3 degradation, chlorination experiments with different added concentrations of bromide and/or ammonia were conducted. Under these conditions, BP-3 degradation was found to be enhanced in the presence of bromide due to the formation of bromine, whereas it was inhibited in the presence of ammonia. However, the results obtained were pH dependent. Finally, a kinetic model considering 18 reactions was developed using Copasi to estimate BP-3 degradation during chlorination in the presence of bromide and ammonia.

  4. Kinetic Spectrophotometric Method for Trace Amounts Determination of Bromide in Pharmaceutical Samples Using Janus Green-Bromate System

    Directory of Open Access Journals (Sweden)

    Masoud Reza Shishehbore

    2011-01-01

    Full Text Available A new simple and rapid kinetic spectrophotometric method has been developed to trace amounts determination of bromide. This method is based on the catalytic effect of bromide on the reaction between Janus Green and bromate in sulfuric acid media. The reaction was followed spectrophotometrically by measuring the absorbance at 618 nm. The fixed-time method was used for the first 210 s. The influence of reagents concentration, temperature and time on the sensitivity was studied. Under optimum experimental conditions, bromide can be determined in the range of 10.0-1800.0 μg/L. The relative standard deviations (n = 10 were 0.22 and 0.19% for 100.0 and 1000.0 g/L of bromide, respectively. The detection limit of the proposed method was 4.1 μg/L. The influence of potential interfering of some ions and biological species on the selectivity was studied. The proposed method was successfully applied for the determination of bromide in pharmaceutical samples. The new developed method was found to have fairly good selectivity, sensitivity, simplicity and rapidity.

  5. Kinetic analysis of the inhibition of the drug efflux protein AcrB using surface plasmon resonance.

    Science.gov (United States)

    Mowla, Rumana; Wang, Yinhu; Ma, Shutao; Venter, Henrietta

    2018-04-01

    Multidrug efflux protein complexes such as AcrAB-TolC from Escherichia coli are paramount in multidrug resistance in Gram-negative bacteria and are also implicated in other processes such as virulence and biofilm formation. Hence efflux pump inhibition, as a means to reverse antimicrobial resistance in clinically relevant pathogens, has gained increased momentum over the past two decades. Significant advances in the structural and functional analysis of AcrB have informed the selection of efflux pump inhibitors (EPIs). However, an accurate method to determine the kinetics of efflux pump inhibition was lacking. In this study we standardised and optimised surface plasmon resonance (SPR) to probe the binding kinetics of substrates and inhibitors to AcrB. The SPR method was also combined with a fluorescence drug binding method by which affinity of two fluorescent AcrB substrates were determined using the same conditions and controls as for SPR. Comparison of the results from the fluorescent assay to those of the SPR assay showed excellent correlation and provided validation for the methods and conditions used for SPR. The kinetic parameters of substrate (doxorubicin, novobiocin and minocycline) binding to AcrB were subsequently determined. Lastly, the kinetics of inhibition of AcrB were probed for two established inhibitors (phenylalanine arginyl β-naphthylamide and 1-1-naphthylmethyl-piperazine) and three novel EPIs: 4-isobutoxy-2-naphthamide (A2), 4-isopentyloxy-2-naphthamide (A3) and 4-benzyloxy-2-naphthamide (A9) have also been probed. The kinetic data obtained could be correlated with inhibitor efficacy and mechanism of action. This study is the first step in the quantitative analysis of the kinetics of inhibition of the clinically important RND-class of multidrug efflux pumps and will allow the design of improved and more potent inhibitors of drug efflux pumps. This article is part of a Special Issue entitled: Beyond the Structure-Function Horizon of Membrane

  6. Kinetics and mechanism of cetyltrimethylammonium bromide catalyzed oxidation of diethylene glycol by chloramine-T in acidic medium

    Directory of Open Access Journals (Sweden)

    A. CHOUBE

    2003-07-01

    Full Text Available The kinetics and mechanism of the C16TAB catalyzed oxidation of diethylene glycol (2,2’-oxydiethanol by chloramine-T in acidic medium has been studied. The reaction has a first-order dependence on chloramine-T. With excess concentrations of other reactants, the reaction rate follows fractional order kinetics with respect to [diethylene glycol]. The micellar effect due to cetyltrimethylammonium bromide, a cationic surfactant, has been studied. The reaction is catalyzed by chloride ions as well. The small salt effect and increase in the reaction rate with increasing dielectric constant suggest the involvement of neutral molecules in the rate determining step. Addition of p-toluenesulfonamide retards the reaction rate. On the basis of product analysis, a pertinent mechanism is proposed.

  7. Titrimetric, spectrophotometric and kinetic methods for the assay of atenolol using bromate–bromide and methyl orange

    Directory of Open Access Journals (Sweden)

    KANAKAPURA BASAVAIAH

    2006-05-01

    Full Text Available Three new methods have been developed for the determination of atenolol in bulk drug and in tablet formulation. The methods are based on the oxidation–bromination reaction of the drug by bromine, generated in situ by the action of acid on a bromate–bromide mixture. In the titrimetric method, the drug is treated with a known excess of bromate–bromide mixture in hydrochloric acid medium, followed by the determination of the unreacted bromine iodometrically. The spectrophotometric method involves the addition of a measured excess of bromate–bromide reagent in hydrochloric acid medium to atenolol, and after ensuring the reaction had gone to completion, the unreacted bromine is treated with a fixed amount of methyl orange, and absorbance measured at 520 nm. The absorbance was found to increase linearly with increasing concentration of atenolol. The kinetic method depends on the existence of a linear relationship between the concentration of the drug and the time of the oxidation–bromination reaction, as indicated by the bleaching of methyl orange acid colour. The working conditions were optimized. The titrimetric method is based on a 1:1 reaction stoichiometry (atenolol:bromate and is applicable over the 3–20 mg range. The spectrophotometric method permits micro determination of the drug (0.5–4.0 mg ml-1with an apparentmolar absorptivity of 4.13x104 lmol-1 cm-1 and detection limit of 0.07 mg ml-1. The kinetic method is applicable in the concentration range 5–25 mg ml-1 with a detection limit of 3.72 mg ml-1. The proposed methods were successfully applied to the determination of atenolol in tablet preparations with mean recoveries of 97.63 to 101.78 %. The reliability of the assay was established by parallel determination by the reference method and by recovery studies using the standard addition technique.

  8. A kinetic study of the thermal degradation of cetyltrimethylammonium bromide inside the mesoporous SBA-3 molecular sieve

    Directory of Open Access Journals (Sweden)

    DJORDJE STOJAKOVIC

    2007-12-01

    Full Text Available The thermal degradation of cetyltrimethylammonium bromide (CTMAB inside the mesoporous SBA-3 was studied under non-isothermal conditions. There are two distinct and complex kinetic processes which partly overlap, each consisting of one dominant and three minor individual processes. The two dominant processes can be described by the Sestak–Berggren model. The main decomposition step (the first dominant process involves the overcoming of weak interactions between CTMAB and the silica network and proceeds with a lower Ea value (116±2 kJ mol‑1 than the second dominant process (153±5 kJ mol-1, which can be explained by the size reduction of the pore openings due to the contraction of the SBA-3 unit cell caused by the removal of CTMAB.

  9. Modeling of Cd Uptake and Efflux Kinetics in Metal-Resistant Bacterium Cupriavidus metallidurans

    NARCIS (Netherlands)

    Hajdu, R.; Pinheiro, J.P.; Galceran, J.; Slaveykova, V.I.

    2010-01-01

    The Model of Uptake with Instantaneous Adsorption and Efflux, MUIAE, describing and predicting the overall Cd uptake by the metal-resistant bacterium Cupriavidus metallidurans CH34, is presented. MUIAE takes into account different processes at the bacteria-medium interface with specific emphasis on

  10. Comparative microvascular exchange kinetics of [{sup 77}Br]bromide and {sup 99m}Tc-DTPA in humans

    Energy Technology Data Exchange (ETDEWEB)

    Cousins, Claire [Department of Clinical Radiology, Addenbrooke' s Hospital, Cambridge (United Kingdom); Skehan, Stephen J.; Rolph, Susan M.; Flaxman, Mary E.; Ballinger, James R.; Bird, Nicholas J.; Barber, Robert W.; Peters, Michael A. [Department of Nuclear Medicine, Addenbrooke' s Hospital, Cambridge (United Kingdom)

    2002-05-01

    The plasma clearance curves of small hydrophilic solutes comprise three exponentials, consistent with a three-compartmental distribution model. A previous comparison between inulin and diethylene triamine penta-acetic acid (DTPA) suggested that these three compartments are in series, the first being plasma and the second and third representing compartments within the extravascular space. Moreover, whilst the total distribution volumes of these two indicators were similar, the volume of the second compartment was higher for DTPA. The purpose of the current study was to investigate whether a solute smaller than DTPA, namely bromide, fits the hypothesis that the second space volume is an inverse function of the size of the solute. Two groups of subjects were studied: group A comprised eight patients undergoing routine diagnostic arteriography and group B, eight patients referred for routine measurement of glomerular filtration rate plus two normal volunteers. {sup 99m}Tc-DTPA and sodium [{sup 77}Br]bromide were intravenously administered simultaneously. In group A, frequent arterial samples were obtained up to 40 min after injection, and antecubital venous samples 30 s after each arterial sample. In group B, frequent venous samples were obtained up to 280 min after injection. Volume measurements based on bromide were corrected for erythrocyte bromide accumulation. In both subject groups, the normalised venous concentration ratio of bromide to DTPA, corrected for red cell bromide uptake, was significantly less than unity in the earliest blood samples, being 0.56 (SD 0.08) at 1 min, consistent with faster diffusion of bromide from plasma to interstitial fluid. Furthermore, the extraction fraction of bromide from plasma to interstitial fluid in the forearm was about 0.6, higher than that of DTPA (about 0.5) in spite of red cell bromide accumulation which equilibrated with plasma bromide within 20 s and resulted in a red cell to plasma concentration ratio of 0.51 (0

  11. Organic chemistry on cold molecular films: kinetic stabilization of SN1 and SN2 intermediates in the reactions of ethanol and 2-methylpropan-2-ol with hydrogen bromide.

    Science.gov (United States)

    Park, Seong-Chan; Maeng, Kye-Won; Kang, Heon

    2003-04-14

    We prepared thin molecular films of ethanol and 2-methylpropan-2-ol on Ru(001) substrates at temperature of 100-150 K and examined their reactivity toward HBr. The reaction intermediates and products formed at the surfaces were unambiguously identified by the techniques of Cs(+) reactive ion scattering (RIS) and low-energy sputtering. The reaction on the ethanol surface produced protonated ethanol, which is stabilized on the surface and does not proceed to further reactions. On the 2-methylpropan-2-ol surface, protonated alcohol [(CH(3))(3)COH(2) (+)] and carbocation [(CH(3))(3)C(+)] were formed with the respective yield of 20 and 78 %. Alkyl bromides, which are the final products of the corresponding reactions in liquid solvents, have extremely small yields on these surfaces (< 0.3 % for ethyl bromide and 2 % for tert-butyl bromide). The results indicate that the reactions on frozen films are characterized by kinetic control, stabilization of ionic intermediates (protonated alcohols and tert-butyl cation), and effective blocking of the charge recombination steps in S(N)1 and S(N)2 paths. The implication of these findings for the molecular evolution process in interstellar medium is also discussed.

  12. Aclidinium Bromide

    DEFF Research Database (Denmark)

    Ulrik, Charlotte Suppli

    2012-01-01

    Long-acting bronchodilators are the mainstay of pharmacological treatment for patients with chronic obstructive pulmonary disease (COPD). The aim of this review is to provide an overview of the clinical studies evaluating the safety and efficacy of inhaled aclidinium bromide, a novel long......-acting anticholinergic bronchodilator, for the treatment of COPD....

  13. Isotherm, thermodynamic, kinetics, and adsorption mechanism studies of Ethidium bromide by single-walled carbon nanotube and carboxylate group functionalized single-walled carbon nanotube.

    Science.gov (United States)

    Moradi, Omid; Fakhri, Ali; Adami, Saeideh; Adami, Sepideh

    2013-04-01

    The studies of kinetics and thermodynamics of adsorption of Ethidium bromide in aqueous solutions on single-walled carbon nanotube (SWCNT) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces were by UV-Vis spectroscopy. The adsorption kinetics for SWCNT-COOH and SWCNTs were well described by a intra-particle diffusion model, while Langmuir, Freundlich, Harkins-Jura, and Halsey isotherms described the adsorption isotherms, and the adsorption thermodynamic parameters of equilibrium constant (K0), standard free energy (ΔG0), standard enthalpy (ΔH0), and standard entropy changes (ΔS0) were measured. The maximum surface coverage for SWCNTs is 36.10% and for SWCNT-COOH is 38.42%. The values of ΔH0 and ΔG0 suggested that the adsorption of EtBr on SWCNT-COOH and SWCNTs was endothermic and spontaneous. The adsorption of EtBr on SWCNT-COOH is more than SWCNTs surfaces. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Kinetics measurements and in situ Raman spectroscopy of formation of hydrogen-tetrabutylammonium bromide semi-hydrates

    NARCIS (Netherlands)

    Trueba, A.T.; Radović, I.R.; Zevenbergen, J.F.; Kroon, M.C.; Peters, C.J.

    2012-01-01

    The kinetics of formation of H2-TBAB semi-clathrate hydrates was studied in this work in order to elucidate their potential for H2 storage. The influence of pressure (5-16 MPa), TBAB concentration (2.6 mol% and 3.7 mol%) and formation method (T-cycle method and T-constant method) on the hydrate

  15. Inhibition of HERG potassium channels by domiphen bromide and didecyl dimethylammonium bromide.

    Science.gov (United States)

    Long, Yan; Chen, Wanjuan; Lin, Zuoxian; Sun, Hongmao; Xia, Menghang; Zheng, Wei; Li, Zhiyuan

    2014-08-15

    Domiphen bromide and didecyl dimethylammonium bromide were widely used environmental chemicals with potent activity on blockade of human ether-a-go-go related gene (HERG) channels. But the mechanism of their action is not clear. The kinetics of block of HERG channels by domiphen bromide and didecyl dimethylammonium bromide was studied in order to characterize the inhibition of HERG currents by these quaternary ammonium compounds (QACs). Domiphen bromide and didecyl dimethylammonium bromide inhibited HERG channel currents in a dose-dependent manner with IC50 values of 9nM and 5nM, respectively. Block of HERG channel by domiphen bromide and didecyl dimethylammonium bromide was voltage-dependent and use-dependent. Domiphen bromide and didecyl dimethylammonium bromide caused substantial negative shift of the activation curves, accelerated activated process, but had no effects on the deactivation and reactivation processes. The docking models implied that these two compounds bound to PAS domain of HERG channels and inhibited its function. Our data demonstrated that domiphen bromide and didecyl dimethylammonium bromide blocked the HERG channel with a preference for the activated channel state. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Efflux inhibitor suppresses Streptococcus mutans virulence properties.

    Science.gov (United States)

    Zeng, Huihui; Liu, Jia; Ling, Junqi

    2017-04-01

    It is well established that efflux pumps play important roles in bacterial pathogenicity and efflux inhibitors (EIs) have been proved to be effective in suppressing bacterial virulence properties. However, little is known regarding the EI of Streptococcus mutans, a well-known caries-inducing bacterium. In this study, we identified the EI of S. mutans through ethidium bromide efflux assay and investigated how EI affected S. mutans virulence regarding the cariogenicity and stress response. Results indicated that reserpine, the identified EI, suppressed acid tolerance, mutacin production and transformation efficiency of S. mutans, and modified biofilm architecture and extracellular polysaccharide distribution. Suppressed glycosyltransferase activity was also noted after reserpine exposure. The data from quantitative real-time-PCR demonstrated that reserpine significantly altered the expression profile of quorum-sensing and virulence-associated genes. These findings suggest that reserpine represents a promising adjunct anticariogenic agent in that it suppresses virulence properties of S. mutans. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. N-(2-Bromobenzylcinchoninium bromide

    Directory of Open Access Journals (Sweden)

    Agnieszka Skórska-Stania

    2012-09-01

    Full Text Available The title compound {systematic name: 1-(2-bromobenzyl-5-ethenyl-2-[hydroxy(quinolin-4-ylmethyl]-1-azabicyclo[2.2.2]octan-1-ium bromide}, C26H28BrN2O+·Br−, is a chiral quaternary ammonium salt of one of the Cinchona alkaloids. The planes of the quinoline and of the bromobenzyl substituent are inclined to one another by 9.11 (9°. A weak intramolecular C—H...O hydrogen bond occurs. The crystal structure features strong O—H...Br hydrogen bonds and weak C—H...Br interactions.

  18. Uptake and efflux kinetics, and intracellular activity of voriconazole against Aspergillus fumigatus in human pulmonary epithelial cells: a new application for the prophylaxis and early treatment of invasive pulmonary aspergillosis.

    Science.gov (United States)

    Wang, Taotao; Yang, Qianting; Chen, Lu; Li, Ying; Meng, Ti; Wang, Yan; Zhang, Tao; Lei, Jin'e; Xing, Jianfeng; Dong, Yalin

    2017-06-01

    Invasive pulmonary aspergillosis (IPA), most caused by Aspergillus fumigatus, is a serious life-threatening infection in immunocompromised patients. Voriconazole is used to prevent and treat IPA. However, little is known about the pharmacological characteristics of voriconazole in pulmonary epithelial cells, which are the target site for the prophylaxis and early treatment of IPA. The aim of the study was to evaluate the kinetics and activity of voriconazole against A. fumigatus in A549 cells. High-performance liquid chromatography/tandem mass spectrometry and time-kill method were used to study the cellular pharmacokinetic and pharmacodynamics of voriconazole. Voriconazole exerted a concentration-dependent toxic effect on A549 cells and could penetrate into cells, reaching plateau concentrations of 1.14 ± 0.64, 3.72 ± 1.38 and 6.36 ± 0.95 ng/mg protein after A549 cells were exposed to voriconazole at extracellular concentrations of 2, 8 and 16 mg/L for 2 h, respectively. The efflux of voriconazole was rapid, with a half-life of 10.2 min. Voriconazole can decrease the A. fumigatus conidia invade cells, and the number of viable A. fumigatus conidia in cells can be decreased 2.1- to 20.6-fold when A549 cells were cultured in medium containing voriconazole. After 24-h incubation, 75.6% and 80.5% of intracellular A. fumigatus were killed when extracellular voriconazole concentration was 8 and 16 mg/L, respectively. This study illustrated a new application for the prophylaxis and early treatment of IPA from the cellular pharmacokinetics and pharmacodynamics and emphasized the importance of monitoring concentrations of voriconazole in epithelial lining fluid in immunocompromised patients receiving voriconazole therapy. © 2016 Société Française de Pharmacologie et de Thérapeutique.

  19. Enhancement of antibiotic activity by efflux inhibitors against multidrug resistant Mycobacterium tuberculosis clinical isolates from Brazil

    Directory of Open Access Journals (Sweden)

    Tatiane eCoelho

    2015-04-01

    Full Text Available Drug resistant tuberculosis continues to increase and new approaches for its treatment are necessary. The identification of M. tuberculosis clinical isolates presenting efflux as part of their resistant phenotype has a major impact in tuberculosis treatment. In this work, we used a checkerboard procedure combined with the tetrazolium microplate-based assay (TEMA to study single combinations between antituberculosis drugs and efflux inhibitors (EIs against multidrug resistant M. tuberculosis clinical isolates using the fully susceptible strain H37Rv as reference. Efflux activity was studied on a real-time basis by a fluorometric method that uses ethidium bromide as efflux substrate. Quantification of efflux pump genes mRNA transcriptional levels were performed by RT-qPCR. The fractional inhibitory concentrations (FIC indicated synergistic activity for the interactions between isoniazid, rifampicin, amikacin, ofloxacin, and ethidium bromide plus the EIs verapamil, thioridazine and chlorpromazine. The FICs ranged from 0.25, indicating a four-fold reduction on the MICs, to 0.015, 64-fold reduction. The detection of active efflux by real-time fluorometry showed that all strains presented intrinsic efflux activity that contributes to the overall resistance which can be inhibited in the presence of the EIs. The quantification of the mRNA levels of the most important efflux pump genes on these strains shows that they are intrinsically predisposed to expel toxic compounds as the exposure to subinhibitory concentrations of antibiotics were not necessary to increase the pump mRNA levels when compared with the non-exposed counterpart. The results obtained in this study confirm that the intrinsic efflux activity contributes to the overall resistance in multidrug resistant clinical isolates of M. tuberculosis and that the inhibition of efflux pumps by the EIs can enhance the clinical effect of antibiotics that are their substrates.

  20. Enhancement of antibiotic activity by efflux inhibitors against multidrug resistant Mycobacterium tuberculosis clinical isolates from Brazil

    Science.gov (United States)

    Coelho, Tatiane; Machado, Diana; Couto, Isabel; Maschmann, Raquel; Ramos, Daniela; von Groll, Andrea; Rossetti, Maria L.; Silva, Pedro A.; Viveiros, Miguel

    2015-01-01

    Drug resistant tuberculosis continues to increase and new approaches for its treatment are necessary. The identification of M. tuberculosis clinical isolates presenting efflux as part of their resistant phenotype has a major impact in tuberculosis treatment. In this work, we used a checkerboard procedure combined with the tetrazolium microplate-based assay (TEMA) to study single combinations between antituberculosis drugs and efflux inhibitors (EIs) against multidrug resistant M. tuberculosis clinical isolates using the fully susceptible strain H37Rv as reference. Efflux activity was studied on a real-time basis by a fluorometric method that uses ethidium bromide as efflux substrate. Quantification of efflux pump genes mRNA transcriptional levels were performed by RT-qPCR. The fractional inhibitory concentrations (FIC) indicated synergistic activity for the interactions between isoniazid, rifampicin, amikacin, ofloxacin, and ethidium bromide plus the EIs verapamil, thioridazine and chlorpromazine. The FICs ranged from 0.25, indicating a four-fold reduction on the MICs, to 0.015, 64-fold reduction. The detection of active efflux by real-time fluorometry showed that all strains presented intrinsic efflux activity that contributes to the overall resistance which can be inhibited in the presence of the EIs. The quantification of the mRNA levels of the most important efflux pump genes on these strains shows that they are intrinsically predisposed to expel toxic compounds as the exposure to subinhibitory concentrations of antibiotics were not necessary to increase the pump mRNA levels when compared with the non-exposed counterpart. The results obtained in this study confirm that the intrinsic efflux activity contributes to the overall resistance in multidrug resistant clinical isolates of M. tuberculosis and that the inhibition of efflux pumps by the EIs can enhance the clinical effect of antibiotics that are their substrates. PMID:25972842

  1. A MATE Family Multidrug Efflux Transporter Pumps out Fluoroquinolones in Bacteroides thetaiotaomicron

    Science.gov (United States)

    Miyamae, Shin; Ueda, Ohmi; Yoshimura, Fuminobu; Hwang, Jaiweon; Tanaka, Yoshinobu; Nikaido, Hiroshi

    2001-01-01

    We cloned a gene, bexA, that codes for a multidrug efflux transporter from the chromosomal DNA of Bacteroides thetaiotaomicron ATCC 29741 by using an Escherichia coli ΔacrAB ΔacrEF mutant as a host. Although the initial recombinant construct contained other open reading frames, the presence of bexA alone was sufficient to confer to the E. coli host elevated levels of resistance to norfloxacin, ciprofloxacin, and ethidium bromide. Disruption of bexA in B. thetaiotaomicron made the strain more susceptible to norfloxacin, ciprofloxacin, and ethidium bromide, showing that this gene is expressed in this organism and functions as a multidrug efflux pump. The deduced BexA protein sequence was homologous to the protein sequence of Vibrio parahaemolyticus NorM, a multidrug efflux transporter, and thus, BexA belongs to the multidrug and toxic compound extrusion (MATE) family. PMID:11709306

  2. Methylnaltrexone bromide methanol monosolvate

    Directory of Open Access Journals (Sweden)

    Xinbo Zhou

    2012-03-01

    Full Text Available In the title compound [systematic name: (4R,4aS,7aR,12bS-3-cyclopropylmethyl-4a,9-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-3-ium bromide methanol monosolvate], C21H26NO4+·Br−·CH3OH, two of the three six-membered rings adopt chair conformations while the third, which contains a C=C double bond, adopts an approximate half-boat conformation. The 2,3-dihydrofuran ring adopts an envelope conformation. In the crystal, the components are linked by O—H...O and O—H...Br hydrogen bonds. The absolute stereochemistry was inferred from one of the starting materials.

  3. Antibiotic resistance and multidrug-resistant efflux pumps expression in lactic acid bacteria isolated from pozol, a nonalcoholic Mayan maize fermented beverage.

    Science.gov (United States)

    Wacher-Rodarte, Maria Del Carmen; Trejo-Muñúzuri, Tanya Paulina; Montiel-Aguirre, Jesús Fernando; Drago-Serrano, Maria Elisa; Gutiérrez-Lucas, Raúl L; Castañeda-Sánchez, Jorge Ismael; Sainz-Espuñes, Teresita

    2016-05-01

    Pozol is a handcrafted nonalcoholic Mayan beverage produced by the spontaneous fermentation of maize dough by lactic acid bacteria. Lactic acid bacteria (LAB) are carriers of chromosomal encoded multidrug-resistant efflux pumps genes that can be transferred to pathogens and/or confer resistance to compounds released during the fermentation process causing food spoiling. The aim of this study was to evaluate the antibiotic sensibility and the transcriptional expression of ABC-type efflux pumps in LAB isolated from pozol that contributes to multidrug resistance. Analysis of LAB and Staphylococcus (S.) aureus ATCC 29213 and ATCC 6538 control strains to antibiotic susceptibility, minimal inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) to ethidium bromide were based in "standard methods" whereas the ethidium bromide efflux assay was done by fluorometric assay. Transcriptional expression of efflux pumps was analyzed by RT-PCR. LAB showed antibiotic multiresistance profiles, moreover, Lactococcus (L.) lactis and Lactobacillus (L.) plantarum displayed higher ethidium bromide efflux phenotype than S. aureus control strains. Ethidium bromide resistance and ethidium bromide efflux phenotypes were unrelated with the overexpression of lmrD in L. lactics, or the underexpression of lmrA in L. plantarum and norA in S. aureus. These findings suggest that, moreover, the analyzed efflux pumps genes, other unknown redundant mechanisms may underlie the antibiotic resistance and the ethidium bromide efflux phenotype in L. lactis and L. plantarum. Phenotypic and molecular drug multiresistance assessment in LAB may improve a better selection of the fermentation starter cultures used in pozol, and to control the antibiotic resistance widespread and food spoiling for health safety.

  4. kinetics

    Directory of Open Access Journals (Sweden)

    D. E. Panayotounakos

    2002-01-01

    Full Text Available We present the construction of the general solutions concerning the one-dimensional (1D fully dynamic nonlinear partial differential equations (PDEs, for the erosion kinetics. After an uncoupling procedure of the above mentioned equations a second–order nonlinear PDE of the Monge type governing the porosity is derived, the general solution of which is constructed in the sense that a full complement of arbitrary functions (as many as the order is introduced. Afterwards, we specify the above solution according to convenient initial conditions.

  5. Managing nematodes without methyl bromide.

    Science.gov (United States)

    Zasada, Inga A; Halbrendt, John M; Kokalis-Burelle, Nancy; LaMondia, James; McKenry, Michael V; Noling, Joe W

    2010-01-01

    Methyl bromide is an effective pre-plant soil fumigant used to control nematodes in many high-input, high-value crops in the United States, including vegetables, nursery plants, ornamentals, tree fruits, strawberries, and grapes. Because methyl bromide has provided a reliable return on investment for nematode control, many of these commodities have standardized their production practices based on the use of this chemical and will be negatively impacted if effective and economical alternatives are not identified. Alternative control measures based on other chemicals, genetic resistance, and cultural practices require a greater knowledge of nematode biology to achieve satisfactory results. Here, we provide an overview of nematode management practices that we believe will be relied upon heavily in U.S. high-value crop production systems in a world without methyl bromide. Included are case studies of U.S. high-value crop production systems to demonstrate how nematode management practices other than methyl bromide may be incorporated.

  6. Ethidium bromide transport across Mycobacterium smegmatis cell-wall: correlation with antibiotic resistance

    Directory of Open Access Journals (Sweden)

    Couto Isabel

    2011-02-01

    Full Text Available Abstract Background Active efflux systems and reduced cell-wall permeability are considered to be the main causes of mycobacterial intrinsic resistance to many antimicrobials. In this study, we have compared the Mycobacterium smegmatis wild-type strain mc2155 with knockout mutants for porins MspA (the main porin of M. smegmatis and MspC, the efflux pump LfrA (the main efflux pump system of M. smegmatis and its repressor LfrR for their ability to transport ethidium bromide (EtBr on a real-time basis. This information was then correlated with minimum inhibitory concentrations (MICs of several antibiotics in the presence or absence of the efflux inhibitors chlorpromazine, thioridazine and verapamil. Results In the absence of porins MspA and MspC, accumulation of ethidium bromide decreased and the cells became more resistant to several antibiotics, whereas the knockout mutant for the LfrA pump showed increased accumulation of EtBr and increased susceptibility to EtBr, rifampicin, ethambutol and ciprofloxacin. Moreover, the efflux inhibitors caused a reduction of the MICs of streptomycin, rifampicin, amikacin, ciprofloxacin, clarithromycin and erythromycin in most of the strains tested. Conclusions The methodology used in this study demonstrated that porin MspA plays an important role in the influx of quaternary ammonium compounds and antibiotics and that efflux via the LfrA pump is involved in low-level resistance to several antimicrobial drugs in M. smegmatis. The results obtained with this non-pathogenic mycobacterium will be used in future studies as a model for the evaluation of the activity of the same efflux inhibitors on the susceptibility of multidrug resistant strains of Mycobacterium tuberculosis to isoniazid and rifampicin.

  7. Farnesol, a Potential Efflux Pump Inhibitor in Mycobacterium smegmatis

    Directory of Open Access Journals (Sweden)

    Jing Jin

    2010-10-01

    Full Text Available The active multidrug efflux pump (EP has been described as one of the mechanisms involved in the natural drug resistance of bacteria, such as mycobacteria. As a result, the development of efflux pumps inhibitors (EPIs is an important topic. In this study, a checkerboard synergy assay indicated that farnesol both decreased the minimum inhibitory concentration (MIC of ethidium bromide (EtBr 8-fold against Mycobacterium smegmatis (M. smegmatis mc2155 ATCC 700084 when incorporated at a concentration of 32 μg/mL (FICI = 0.625 and decreased MIC 4-fold at 16 μg/mL (FICI = 0.375. Farnesol also showed synergism when combined with rifampicin. A real-time 96-well plate fluorometric method was used to assess the ability of farnesol to inhibit EPs in comparison withfour positive EPIs: chlorpromazine, reserpine, verapamil, and carbonyl cyanide m-chlorophenylhydrazone (CCCP. Farnesol significantly enhanced the accumulation of EtBr and decreased the efflux of EtBr in M. smegmatis; these results suggest that farnesol acts as an inhibitor of mycobacterial efflux pumps.

  8. Identification of natural compound inhibitors for multidrug efflux pumps of Escherichia coli and Pseudomonas aeruginosa using in silico high-throughput virtual screening and in vitro validation.

    Science.gov (United States)

    Aparna, Vasudevan; Dineshkumar, Kesavan; Mohanalakshmi, Narasumani; Velmurugan, Devadasan; Hopper, Waheeta

    2014-01-01

    Pseudomonas aeruginosa and Escherichia coli are resistant to wide range of antibiotics rendering the treatment of infections very difficult. A main mechanism attributed to the resistance is the function of efflux pumps. MexAB-OprM and AcrAB-TolC are the tripartite efflux pump assemblies, responsible for multidrug resistance in P. aeruginosa and E. coli respectively. Substrates that are more susceptible for efflux are predicted to have a common pharmacophore feature map. In this study, a new criterion of excluding compounds with efflux substrate-like features was used, thereby refining the selection process and enriching the inhibitor identification process. An in-house database of phytochemicals was created and screened using high-throughput virtual screening against AcrB and MexB proteins and filtered by matching with the common pharmacophore models (AADHR, ADHNR, AAHNR, AADHN, AADNR, AAADN, AAADR, AAANR, AAAHN, AAADD and AAADH) generated using known efflux substrates. Phytochemical hits that matched with any one or more of the efflux substrate models were excluded from the study. Hits that do not have features similar to the efflux substrate models were docked using XP docking against the AcrB and MexB proteins. The best hits of the XP docking were validated by checkerboard synergy assay and ethidium bromide accumulation assay for their efflux inhibition potency. Lanatoside C and diadzein were filtered based on the synergistic potential and validated for their efflux inhibition potency using ethidium bromide accumulation study. These compounds exhibited the ability to increase the accumulation of ethidium bromide inside the bacterial cell as evidenced by these increase in fluorescence in the presence of the compounds. With this good correlation between in silico screening and positive efflux inhibitory activity in vitro, the two compounds, lanatoside C and diadzein could be promising efflux pump inhibitors and effective to use in combination therapy against drug

  9. Bromide in some coastal and oceanic waters of India

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, F.P.; Dalal, V.N.K.

    Bromide concentration and bromide/chlorinity ratio are estimated in coastal waters of Goa, Minicoy Lagoon, Western Arabian Sea and Western Bay of Bengal. The influence of precipitation and river runoff on bromide and bromide/chlorinity ratio...

  10. Efflux pump genes of the resistance-nodulation-division family in Burkholderia cenocepacia genome

    Directory of Open Access Journals (Sweden)

    Manina Giulia

    2006-07-01

    Full Text Available Abstract Background Burkholderia cenocepacia is recognized as opportunistic pathogen that can cause lung infections in cystic fibrosis patients. A hallmark of B. cenocepacia infections is the inability to eradicate the organism because of multiple intrinsic antibiotic resistance. As Resistance-Nodulation-Division (RND efflux systems are responsible for much of the intrinsic multidrug resistance in Gram-negative bacteria, this study aims to identify RND genes in the B. cenocepacia genome and start to investigate their involvement into antimicrobial resistance. Results Genome analysis and homology searches revealed 14 open reading frames encoding putative drug efflux pumps belonging to RND family in B. cenocepacia J2315 strain. By reverse transcription (RT-PCR analysis, it was found that orf3, orf9, orf11, and orf13 were expressed at detectable levels, while orf10 appeared to be weakly expressed in B. cenocepacia. Futhermore, orf3 was strongly induced by chloramphenicol. The orf2 conferred resistance to fluoroquinolones, tetraphenylphosphonium, streptomycin, and ethidium bromide when cloned and expressed in Escherichia coli KAM3, a strain lacking the multidrug efflux pump AcrAB. The orf2-overexpressing E. coli also accumulate low concentrations of ethidium bromide, which was restored to wild type level in the presence of CCCP, an energy uncoupler altering the energy of the drug efflux pump. Conclusion The 14 RND pumps gene we have identified in the genome of B. cenocepacia suggest that active efflux could be a major mechanism underlying antimicrobial resistance in this microorganism. We have characterized the ORF2 pump, one of these 14 potential RND efflux systems. Its overexpression in E. coli conferred resistance to several antibiotics and to ethidium bromide but it remains to be determined if this pump play a significant role in the antimicrobial intrinsic resistance of B. cenocepacia. The characterization of antibiotic efflux pumps in B

  11. [Efflux systems in Serratia marcescens].

    Science.gov (United States)

    Mardanova, A M; Bogomol'naia, L M; Romanova, Iu D; Sharipova, M R

    2014-01-01

    A widespread bacterium Serratia marcescens (family Enterobacteriaceae) is an opportunistic and exhibits multiple drug resistance. Active removal of antibiotics and other antimicrobials from pathogen and exhibits multiple drug resistance. Active removal of antibiotics and other antimicrobials from the cells by efflux systems is one of the mechanisms responsible for microbial resistance to these compounds. Among enterobacteria, efflux systems of Escherichia coli and Salmonella enterica var. Typhimurium have been studied most extensively. Few efflux systems that belong to different families have been reported for S. marcescens. In this review, we analyzed available literature about S. marcescens efflux systems and carried out the comparative analysis of the genes encoding the RND type systems in different Serratia species and in other enterobacteria. Bioinformatical analysis of the S. marcescens genome allowed us to identify the previously unknown efflux systems based on their homology with the relevant E. coli genes. Identification of additional efflux systems in S. marcescens genome will promote our understanding of physiology of these bacteria, will detect new molecular mechanisms of resistance and will reveal their resistance potential.

  12. Mode of action of the 2-phenylquinoline efflux inhibitor PQQ4R against Escherichia coli.

    Science.gov (United States)

    Machado, Diana; Fernandes, Laura; Costa, Sofia S; Cannalire, Rolando; Manfroni, Giuseppe; Tabarrini, Oriana; Couto, Isabel; Sabatini, Stefano; Viveiros, Miguel

    2017-01-01

    Efflux pump inhibitors are of great interest since their use as adjuvants of bacterial chemotherapy can increase the intracellular concentrations of the antibiotics and assist in the battle against the rising of antibiotic-resistant bacteria. In this work, we have described the mode of action of the 2-phenylquinoline efflux inhibitor (4-(2-(piperazin-1-yl)ethoxy)-2-(4-propoxyphenyl) quinolone - PQQ4R), against Escherichia coli, by studding its efflux inhibitory ability, its synergistic activity in combination with antibiotics, and compared its effects with the inhibitors phenyl-arginine-β-naphthylamide (PAβN) and chlorpromazine (CPZ). The results showed that PQQ4R acts synergistically, in a concentration dependent manner, with antibiotics known to be subject to efflux in E. coli reducing their MIC in correlation with the inhibition of their efflux. Real-time fluorometry assays demonstrated that PQQ4R at sub-inhibitory concentrations promote the intracellular accumulation of ethidium bromide inhibiting its efflux similarly to PAβN or CPZ, well-known and described efflux pump inhibitors for Gram-negative bacteria and whose clinical usage is limited by their levels of toxicity at clinical and bacteriological effective concentrations. The time-kill studies showed that PQQ4R, at bactericidal concentrations, has a rapid antimicrobial activity associated with a fast decrease of the intracellular ATP levels. The results also indicated that the mode of action of PQQ4R involves the destabilization of the E. coli inner membrane potential and ATP production impairment, ultimately leading to efflux pump inhibition by interference with the energy required by the efflux systems. At bactericidal concentrations, membrane permeabilization increases and finally ATP is totally depleted leading to cell death. Since drug resistance mediated by the activity of efflux pumps depends largely on the proton motive force (PMF), dissipaters of PMF such as PQQ4R, can be regarded as future

  13. Mode of action of the 2-phenylquinoline efflux inhibitor PQQ4R against Escherichia coli

    Directory of Open Access Journals (Sweden)

    Diana Machado

    2017-04-01

    Full Text Available Efflux pump inhibitors are of great interest since their use as adjuvants of bacterial chemotherapy can increase the intracellular concentrations of the antibiotics and assist in the battle against the rising of antibiotic-resistant bacteria. In this work, we have described the mode of action of the 2-phenylquinoline efflux inhibitor (4-(2-(piperazin-1-ylethoxy-2-(4-propoxyphenyl quinolone – PQQ4R, against Escherichia coli, by studding its efflux inhibitory ability, its synergistic activity in combination with antibiotics, and compared its effects with the inhibitors phenyl-arginine-β-naphthylamide (PAβN and chlorpromazine (CPZ. The results showed that PQQ4R acts synergistically, in a concentration dependent manner, with antibiotics known to be subject to efflux in E. coli reducing their MIC in correlation with the inhibition of their efflux. Real-time fluorometry assays demonstrated that PQQ4R at sub-inhibitory concentrations promote the intracellular accumulation of ethidium bromide inhibiting its efflux similarly to PAβN or CPZ, well-known and described efflux pump inhibitors for Gram-negative bacteria and whose clinical usage is limited by their levels of toxicity at clinical and bacteriological effective concentrations. The time-kill studies showed that PQQ4R, at bactericidal concentrations, has a rapid antimicrobial activity associated with a fast decrease of the intracellular ATP levels. The results also indicated that the mode of action of PQQ4R involves the destabilization of the E. coli inner membrane potential and ATP production impairment, ultimately leading to efflux pump inhibition by interference with the energy required by the efflux systems. At bactericidal concentrations, membrane permeabilization increases and finally ATP is totally depleted leading to cell death. Since drug resistance mediated by the activity of efflux pumps depends largely on the proton motive force (PMF, dissipaters of PMF such as PQQ4R, can be

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

    Science.gov (United States)

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

    2013-01-01

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

  15. The role of active efflux in antibiotic - resistance of clinical isolates of Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    Falsafi T

    2009-01-01

    Full Text Available Purpose: In gram-negative bacteria, active efflux pumps that excrete drugs can confer resistance to antibiotics however, in Helicobacter pylori this role is not well established. The purpose of this study is to evaluate the role of active efflux in resistance of H. pylori isolates to antibiotics. Materials and Methods: Twelve multiple antibiotic resistant (MAR isolates resistant to at least four antibiotics, including β-lactams, metronidazole, tetracycline, erythromycin, and ciprofloxacin; three resistant to only β-lactams, and two hyper-susceptible isolates, were obtained from screening of 96 clinical isolates of H. pylori . Their minimal inhibitory concentrations (MICs for antibiotics and ethidium-bromide (EtBr were compared in the presence- and absence of a proton-conductor, carbonyl cyanide-m chlorophenyl-hydrazone (CCCP using agar-dilution and disc diffusion. Drug accumulation studies for EtBr and antibiotics were assessed in the presence and absence of CCCP using spectrofluorometry. Results: MIC of EtBr for eight MAR-isolates was decreased two- to four-folds in the presence of CCCP, of which five showed reduced MICs for β-lactam, metronidazole, tetracycline, and ciprofloxacin with CCCP. Accumulation of EtBr by the MAR-isolates was rapid and not dependant on the pattern of multiple resistance. Antibiotic accumulation assay confirmed the presence of energy-dependant efflux of β-lactam, metronidazole, tetracycline, and ciprofloxacin, but no erythromycin in five MAR isolates. Energy-dependant efflux of EtBr or antibiotics was not observed for four MAR-isolates, and three isolates were resistant only to β-lactams. Conclusion: Energy-dependant efflux plays a role in the resistance of H. pylori clinical isolates to structurally unrelated antibiotics in a broadly specific multidrug efflux manner. Difference in the efflux potential of MAR isolates may be related to the presence or absence of functional efflux-pumps in diverse H. pylori

  16. The Multiple Role of Bromide Ion in PPCPs Degradation under UV/Chlorine Treatment.

    Science.gov (United States)

    Cheng, Shuangshuang; Zhang, Xinran; Yang, Xin; Shang, Chii; Song, Weihua; Fang, Jingyun; Pan, Yanheng

    2018-02-05

    This study investigated the role of bromide ions in the degradation of nine pharmaceuticals and personal care products (PPCPs) during the UV/chlorine treatment of simulated drinking water containing 2.5 mgC L-1 natural organic matter (NOM). The kinetics of contributions from UV irradiation and from oxidation by free chlorine, free bromine, hydroxyl radical and reactive halogen species were evaluated. The observed loss rate constants of PPCPs in the presence of 10 μM bromide were 1.6-23 times of those observed in the absence of bromide (except for iopromide and ibuprofen). Bromide was shown to play multiple roles in PPCP degradation. It reacts rapidly with free chlorine to produce a trace amount of free bromine, which then contributes to up to 55% of the degradation of some PPCPs during 15 min of UV/chlorine treatment. Bromide was also shown to reduce the level of HO• and to change the reactive chlorine species to bromine-containing species, which resulted in decreases in ibuprofen degradation and enhancement in carbamazepine and caffeine degradation, respectively. Reactive halogen species contributed to between 37 and 96% of the degradation of the studied PPCPs except ibuprofen in the presence of 10 μM bromide ion. The effect of bromide is non-negligible during the UV/chlorine treatment.

  17. Efflux Pump‑Mediated Resistance in Chemotherapy

    African Journals Online (AJOL)

    to elucidate their structure and mechanisms of action so as to integrate the efflux pump mechanisms in the design and development ... mechanism is very common in resistance to tetracyclines, erythromycin, and fluoroquinolones. ... Antibiotics can act as inducers and regulators of expression of efflux pumps.[7] Several efflux ...

  18. Tiotropium bromide inhibits human monocyte chemotaxis

    Directory of Open Access Journals (Sweden)

    Kurai M

    2012-08-01

    Full Text Available Tiotropium bromide (Spiriva® is used as a bronchodilator in chronic obstructive pulmonary disease (COPD. However, clinical evidence suggests that tiotropium bromide may improve COPD by mechanisms beyond bronchodilation. We hypothesized that tiotropium bromide may act as an anti-inflammatory agent by inhibiting monocyte chemotaxis, a process that plays an important role in the lung inflammation of COPD. To test this hypothesis monocytes were pretreated with tiotropium bromide prior to exposure to chemotactic agents and monocyte chemotactic activity (MCA was evaluated with a blind chamber technique. Tiotropium bromide inhibited MCA in a dose- and time- dependent manner (respectively, p< 0.01 by directly acting on the monocyte. Acetylcholine (ACh challenge increased MCA (p< 0.01, and tiotropium bromide effectively reduced (p< 0.01 the increase in MCA by ACh. The inhibition of MCA by tiotropium bromide was reversed by a muscarinic type 3 (M3-muscarinic receptor antagonist (p< 0.01, and was not effected by an M2 receptor antagonist. Furthermore, a selective M3 receptor agonist, cevimeline, and Gq protein stimulator, Pasteurella multocida toxin, significantly increased MCA (P < 0.01, and tiotropium bromide pretreatment reduced (p< 0.01 the increase in MCA induced by these agents. These results suggest that tiotropium might regulate monocyte chemotaxis, in part, by interfering with M3-muscarinic receptor coupled Gq protein signal transduction. These results provide new insight that an anti-cholinergic therapeutic may provide anti-inflammatory action in the pulmonary system.

  19. Catalytic Effect of Cetyltrimethylammonium Bromide on the Oxidation of Triethylene glycol by Chloramine-T in Acidic Medium

    OpenAIRE

    Sharma, Vandana; Sharma, K. V.; Bhagwat, V. W.

    2008-01-01

    The kinetics and mechanism of cetyltrimethylammonium bromide catalyzed oxidation of triethylene glycol [2,2'-ethylene diqxybis(ethanol)] by chloramine-T in acidic acid medium have been investigated. The reaction is first order dependence on chloramine-T and fractional order for triethylene glycol with excess concentration of other reactants. The catalytic effect due to cetyletrimethylammonium bromide has been studied. The small salt effect and increase in the reaction rate with increasing die...

  20. Peptide mediators of cholesterol efflux

    Energy Technology Data Exchange (ETDEWEB)

    Bielicki, John K.; Johansson, Jan

    2013-04-09

    The present invention provides a family of non-naturally occurring polypeptides having cholesterol efflux activity that parallels that of full-length apolipoproteins (e.g., Apo AI and Apo E), and having high selectivity for ABAC1 that parallels that of full-length apolipoproteins. The invention also provides compositions comprising such polypeptides, methods of identifying, screening and synthesizing such polypeptides, and methods of treating, preventing or diagnosing diseases and disorders associated with dyslipidemia, hypercholesterolemia and inflammation.

  1. Glutathione Efflux and Cell Death

    Science.gov (United States)

    2012-01-01

    Abstract Significance: Glutathione (GSH) depletion is a central signaling event that regulates the activation of cell death pathways. GSH depletion is often taken as a marker of oxidative stress and thus, as a consequence of its antioxidant properties scavenging reactive species of both oxygen and nitrogen (ROS/RNS). Recent Advances: There is increasing evidence demonstrating that GSH loss is an active phenomenon regulating the redox signaling events modulating cell death activation and progression. Critical Issues: In this work, we review the role of GSH depletion by its efflux, as an important event regulating alterations in the cellular redox balance during cell death independent from oxidative stress and ROS/RNS formation. We discuss the mechanisms involved in GSH efflux during cell death progression and the redox signaling events by which GSH depletion regulates the activation of the cell death machinery. Future Directions: The evidence summarized here clearly places GSH transport as a central mechanism mediating redox signaling during cell death progression. Future studies should be directed toward identifying the molecular identity of GSH transporters mediating GSH extrusion during cell death, and addressing the lack of sensitive approaches to quantify GSH efflux. Antioxid. Redox Signal. 17, 1694–1713. PMID:22656858

  2. Lack of AcrB Efflux Function Confers Loss of Virulence on Salmonella enterica Serovar Typhimurium

    Directory of Open Access Journals (Sweden)

    Xuan Wang-Kan

    2017-07-01

    Full Text Available AcrAB-TolC is the paradigm resistance-nodulation-division (RND multidrug resistance efflux system in Gram-negative bacteria, with AcrB being the pump protein in this complex. We constructed a nonfunctional AcrB mutant by replacing D408, a highly conserved residue essential for proton translocation. Western blotting confirmed that the AcrB D408A mutant had the same native level of expression of AcrB as the parental strain. The mutant had no growth deficiencies in rich or minimal medium. However, compared with wild-type SL1344, the mutant had increased accumulation of Hoechst 33342 dye and decreased efflux of ethidium bromide and was multidrug hypersusceptible. The D408A mutant was attenuated in vivo in mouse and Galleria mellonella models and showed significantly reduced invasion into intestinal epithelial cells and macrophages in vitro. A dose-dependent inhibition of invasion was also observed when two different efflux pump inhibitors were added to the wild-type strain during infection of epithelial cells. RNA sequencing (RNA-seq revealed downregulation of bacterial factors necessary for infection, including those in the Salmonella pathogenicity islands 1, 2, and 4; quorum sensing genes; and phoPQ. Several general stress response genes were upregulated, probably due to retention of noxious molecules inside the bacterium. Unlike loss of AcrB protein, loss of efflux function did not induce overexpression of other RND efflux pumps. Our data suggest that gene deletion mutants are unsuitable for studying membrane transporters and, importantly, that inhibitors of AcrB efflux function will not induce expression of other RND pumps.

  3. Antibacterial and efflux pump inhibitors of thymol and carvacrol against food-borne pathogens.

    Science.gov (United States)

    Miladi, Hanene; Zmantar, Tarek; Chaabouni, Yassine; Fedhila, Kais; Bakhrouf, Amina; Mahdouani, Kacem; Chaieb, Kamel

    2016-10-01

    In this study thymol (THY) and carvacrol (CAR), two monoterpenic phenol produced by various aromatic plants, was tested for their antibacterial and efflux pump inhibitors potencies against a panel of clinical and foodborne pathogenes. Our results demonstrated a substantial susceptibility of the tested bacteria toward THY and CAR. Especially, THY displayed a strong inhibitory activity (MIC's values ranged from 32 to 64 μg/mL) against the majority of the tested strains compared to CAR. Moreover, a significant reduction in MIC's of TET and benzalkonium chloride (QAC) were noticed when tested in combinations with THY and CAR. Their synergic effect was more significant in the case of THY which resulted a reduction of MIC's values of TET (2-8 fold) and QAC (2-8 fold). We noted also that THY and CAR inhibited the ethidium bromide (EtBr) cell efflux in a concentration-dependent manner. The rate of EtBr accumulation in food-borne pathogen was enhanced with THY and CAR (0, 250 and 500 μg/mL). The lowest concentration causing 50% of EtBr efflux inhibition (IC 50) was noticed in Salmonella enteritidis (1129) at 150 μg/mL of THY and 190 μg/mL of CAR respectively. These findings indicate that THY and CAR may serve as potential sources of efflux pump inhibitor in food-borne pathogens. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Modulation of the multidrug efflux pump EmrD-3 from Vibrio cholerae by Allium sativum extract and the bioactive agent allyl sulfide plus synergistic enhancement of antimicrobial susceptibility by A. sativum extract.

    Science.gov (United States)

    Bruns, Merissa M; Kakarla, Prathusha; Floyd, Jared T; Mukherjee, Mun Mun; Ponce, Robert C; Garcia, John A; Ranaweera, Indrika; Sanford, Leslie M; Hernandez, Alberto J; Willmon, T Mark; Tolson, Grace L; Varela, Manuel F

    2017-04-21

    The causative agent of cholera, Vibrio cholerae, is a public health concern. Multidrug-resistant V. cholerae variants may reduce chemotherapeutic efficacies of severe cholera. We previously reported that the multidrug efflux pump EmrD-3 from V. cholerae confers resistance to multiple structurally distinct antimicrobials. Medicinal plant compounds are potential candidates for EmrD-3 efflux pump modulation. The antibacterial activities of garlic Allium sativum, although poorly understood, predicts that a main bioactive component, allyl sulfide, modulates EmrD-3 efflux. Thus, we tested whether A. sativum extract acts in synergy with antimicrobials and that a main bioactive component allyl sulfide inhibits EmrD-3 efflux. We found that A. sativum extract and allyl sulfide inhibited ethidium bromide efflux in cells harboring EmrD-3 and that A. sativum lowered the MICs of multiple antibacterials. We conclude that A. sativum and allyl sulfide inhibit EmrD-3 and that A. sativum extract synergistically enhances antibacterial agents.

  5. The in vitro and in vivo profile of aclidinium bromide in comparison with glycopyrronium bromide.

    Science.gov (United States)

    Gavaldà, Amadeu; Ramos, Israel; Carcasona, Carla; Calama, Elena; Otal, Raquel; Montero, José Luis; Sentellas, Sonia; Aparici, Monica; Vilella, Dolors; Alberti, Joan; Beleta, Jorge; Miralpeix, Montserrat

    2014-08-01

    This study characterised the in vitro and in vivo profiles of two novel long-acting muscarinic antagonists, aclidinium bromide and glycopyrronium bromide, using tiotropium bromide and ipratropium bromide as comparators. All four antagonists had high affinity for the five muscarinic receptor sub-types (M1-M5); aclidinium had comparable affinity to tiotropium but higher affinity than glycopyrronium and ipratropium for all receptors. Glycopyrronium dissociated faster from recombinant M3 receptors than aclidinium and tiotropium but more slowly than ipratropium; all four compounds dissociated more rapidly from M2 receptors than from M3 receptors. In vitro, aclidinium, glycopyrronium and tiotropium had a long duration of action at native M3 receptors (>8 h versus 42 min for ipratropium). In vivo, all compounds were equi-potent at reversing acetylcholine-induced bronchoconstriction. Aclidinium, glycopyrronium and ipratropium had a faster onset of bronchodilator action than tiotropium. Aclidinium had a longer duration of action than glycopyronnium (time to 50% recovery of effect [t½ offset] = 29 h and 13 h, respectively); these compare with a t½ offset of 64 h and 8 h for tiotropium and ipratropium, respectively. Aclidinium was less potent than glycopyrronium and tiotropium at inhibiting salivation in conscious rats (dose required to produce half-maximal effect [ED50] = 38, 0.74 and 0.88 μg/kg, respectively) and was more rapidly hydrolysed in rat, guinea pig and human plasma compared with glycopyrronium or tiotropium. These results indicate that while aclidinium and glycopyrronium are both potent antagonists at muscarinic receptors with similar kinetic selectivity for M3 receptors versus M2, aclidinium has a longer dissociation half-life at M3 receptors and a longer duration of bronchodilator action in vivo than glycopyrronium. The rapid plasma hydrolysis of aclidinium, coupled to its kinetic selectivity, may confer a reduced propensity for systemic

  6. The Role of Efflux Pumps in Schistosoma mansoni Praziquantel Resistant Phenotype

    Science.gov (United States)

    Armada, Ana; Belo, Silvana; Carrilho, Emanuel; Viveiros, Miguel; Afonso, Ana

    2015-01-01

    Background Schistosomiasis is a neglected disease caused by a trematode of the genus Schistosoma that is second only to malaria in public health significance in Africa, South America, and Asia. Praziquantel (PZQ) is the drug of choice to treat this disease due to its high cure rates and no significant side effects. However, in the last years increasingly cases of tolerance to PZQ have been reported, which has caused growing concerns regarding the emergency of resistance to this drug. Methodology/Principal Findings Here we describe the selection of a parasitic strain that has a stable resistance phenotype to PZQ. It has been reported that drug resistance in helminths might involve efflux pumps such as members of ATP-binding cassette transport proteins, including P-glycoprotein and multidrug resistance-associated protein families. Here we evaluate the role of efflux pumps in Schistosoma mansoni resistance to PZQ, by comparing the efflux pumps activity in susceptible and resistant strains. The evaluation of the efflux activity was performed by an ethidium bromide accumulation assay in presence and absence of Verapamil. The role of efflux pumps in resistance to PZQ was further investigated comparing the response of susceptible and resistant parasites in the absence and presence of different doses of Verapamil, in an ex vivo assay, and these results were further reinforced through the comparison of the expression levels of SmMDR2 RNA by RT-PCR. Conclusions/Significance This work strongly suggests the involvement of Pgp-like transporters SMDR2 in Praziquantel drug resistance in S. mansoni. Low doses of Verapamil successfully reverted drug resistance. Our results might give an indication that a combination therapy with PZQ and natural or synthetic Pgp modulators can be an effective strategy for the treatment of confirmed cases of resistance to PZQ in S. mansoni. PMID:26445012

  7. Identification of interspecies difference in efflux transporters of hepatocytes from dog, rat, monkey and human.

    Science.gov (United States)

    Li, Meng; Yuan, Haodan; Li, Na; Song, Guotao; Zheng, Yi; Baratta, Mike; Hua, Fengmei; Thurston, Archie; Wang, Joanne; Lai, Yurong

    2008-09-02

    The large interspecies differences of hepatobiliary transport present a challenge for the allometric prediction of human biliary excretion for drug candidates primarily cleared via hepatobiliary secretion. In the present study, we determined the metabolic stabilities of common fluorescent substrates of hepatobiliary efflux transporters and developed a rapid efflux assay to determine the functional activities of MRP/Mrp, BCRP/Bcrp and P-gp in hepatocytes of four species. The specificities of transporter-mediated dye efflux were confirmed by selective transporter inhibitors. Among tested species, transporter-specific dye efflux kinetics was consistent between freshly isolated and cryopreserved hepatocytes. Hepatocyte elimination half-lives of MRP/Mrp substrates GS-MF and calcein were observed in the rank order of human>monkey>dog>rat. The fourfold higher MRP/Mrp substrate efflux rate of rat hepatocytes compared to human is likely due to the species-specific functional differences of MRP2/Mrp2 expressed on the canalicular membrane. We also observed efficient BCRP-mediated pheophorbide A (PhA) efflux by human and dog hepatocytes, while PhA extrusion in monkey and rat hepatocytes appeared limited. P-gp function measured by DiOC2(3) efflux was minimal in hepatocytes of all origins and no significant species differences were detected. Our results demonstrated marked differences in hepatocyte MRP/Mrp and BCRP/Bcrp activities across species, indicating that they may contribute to the species differences of in vivo hepatobiliary excretion. These results also suggest the potential utility of primary hepatocytes, either fresh or cryopreserved, as an in vitro model to predict interspecies differences in the biliary transport of MRP/Mrp and BCRP/Bcrp substrates.

  8. 77 FR 35295 - Methyl Bromide; Pesticide Tolerances

    Science.gov (United States)

    2012-06-13

    ... ] not limited to those engaged in the following activities: Crop production (NAICS code 111). Animal... the proposed rule. EPA's response to these comments is discussed in Unit III. III. Response to... considerably more opportunity for digestion and detoxification of a simple molecule such as methyl bromide in...

  9. Electrical polarization of lead bromide crystals. I

    NARCIS (Netherlands)

    Schoonman, A.; Macke, A.J.H.

    An attempt was made to measure electronic conductivity in lead bromide in equilibrium with lead, since experimental data on the cell −Pb/PbBr2/C+ in the literature are not consistent with existing theories. Combination of our results with published data for bromine-induced hole conduction in lead

  10. NorA efflux pump inhibitory activity of coumarins from Mesua ferrea.

    Science.gov (United States)

    Roy, Somendu K; Kumari, Neela; Pahwa, Sonika; Agrahari, Udai C; Bhutani, Kamlesh K; Jachak, Sanjay M; Nandanwar, Hemraj

    2013-10-01

    The purpose of this investigation was to study the modulator and efflux pump inhibitor activity of coumarins isolated from Mesua ferrea against clinical strains as well as NorA-over expressed strain of Staphylococcus aureus 1199B. Seven coumarins were tested for modulator activity using ethidium bromide (EtBr) as a substrate. Compounds 1, 4-7 modulated the MIC of EtBr by ≥ 2 fold against wild type clinical strains of S. aureus 1199 and S. aureus 1199B, whereas compounds 4-7 modulated the MIC of EtBr by ≥ 16 fold against MRSA 831. Compounds 1, 4-7 also reduced the MIC of norfloxacin by ≥ 8 fold against S. aureus 1199B, and 4-6 reduced the MIC of norfloxacin by ≥ 8 fold against MRSA 831 at half of their MICs. Inhibition of EtBr efflux by NorA-overproducing S. aureus 1199B and MRSA 831 confirmed the role of compounds 4-6 as NorA efflux pump inhibitors (EPI). Dose-dependent activity at sub-inhibitory concentration (6.25 μg/mL) suggested that compounds 4 and 5 are promising EPI compared to verapamil against 1199B and MRSA 831 strains. © 2013.

  11. Role of novel multidrug efflux pump involved in drug resistance in Klebsiella pneumoniae.

    Directory of Open Access Journals (Sweden)

    Vijaya Bharathi Srinivasan

    Full Text Available BACKGROUND: Multidrug resistant Klebsiella pneumoniae have caused major therapeutic problems worldwide due to the emergence of the extended-spectrum β-lactamase producing strains. Although there are >10 major facilitator super family (MFS efflux pumps annotated in the genome sequence of the K. pneumoniae bacillus, apparently less is known about their physiological relevance. PRINCIPAL FINDINGS: Insertional inactivation of kpnGH resulting in increased susceptibility to antibiotics such as azithromycin, ceftazidime, ciprofloxacin, ertapenem, erythromycin, gentamicin, imipenem, ticarcillin, norfloxacin, polymyxin-B, piperacillin, spectinomycin, tobramycin and streptomycin, including dyes and detergents such as ethidium bromide, acriflavine, deoxycholate, sodium dodecyl sulphate, and disinfectants benzalkonium chloride, chlorhexidine and triclosan signifies the wide substrate specificity of the transporter in K. pneumoniae. Growth inactivation and direct fluorimetric efflux assays provide evidence that kpnGH mediates antimicrobial resistance by active extrusion in K. pneumoniae. The kpnGH isogenic mutant displayed decreased tolerance to cell envelope stressors emphasizing its added role in K. pneumoniae physiology. CONCLUSIONS AND SIGNIFICANCE: The MFS efflux pump KpnGH involves in crucial physiological functions besides being an intrinsic resistance determinant in K. pneumoniae.

  12. Elevated serum bromide in patients taking lithium carbonate.

    Science.gov (United States)

    Handorf, C R; Coleman, J H; Rawls, W N

    1985-01-01

    Serum bromide levels were determined for 20 patients receiving lithium carbonate for manic depressive illness. Bromides averaged 17.06 +/- 8.15 mg/dl, which exceeded the control average of 3.22 +/- 3.2 mg/dl. Elevated serum bromide in patients taking lithium may reflect altered renal function.

  13. Fosfomycin resistance in Acinetobacter baumannii is mediated by efflux through a major facilitator superfamily (MFS) transporter-AbaF.

    Science.gov (United States)

    Sharma, Atin; Sharma, Rajnikant; Bhattacharyya, Tapas; Bhando, Timsy; Pathania, Ranjana

    2017-01-01

    To decipher the function of A1S_1331, named AbaF (Acinetobacter baumannii Fosfomycin efflux), one of the primary targets of AbsR25, a small RNA of A. baumannii. abaF was cloned in a multicopy plasmid and expressed from its native promoter in an efflux-deficient strain-Escherichia coli KAM32. Drug susceptibility, accumulation and efflux of ethidium bromide (EtBr) were determined in this strain. abaF was disrupted in A. baumannii using homologous recombination and its effect on drug susceptibility, biofilm formation and virulence was studied. Expression of abaF was followed by quantitative PCR in fosfomycin-challenged A. baumannii and fosfomycin-resistant mutants of A. baumannii. Expression of abaF in clinical strains of A. baumannii was determined by RT-PCR. Expression of abaF in E. coli KAM32 resulted in increased resistance to fosfomycin. Lower accumulation and higher efflux of EtBr from this strain confirmed the role of AbaF as an efflux pump. Disruption of abaF in A. baumannii caused an increase in fosfomycin susceptibility and a decrease in biofilm formation and virulence. The expression of abaF was higher in A. baumannii cells exposed to fosfomycin and in cells resistant to higher concentrations of fosfomycin. The clinically relevant strains of A. baumannii also tested positive for the expression of abaF. The results of this study suggest that efflux is an important mechanism of fosfomycin resistance and AbaF is involved in fosfomycin resistance in A. baumannii. AbaF also seems to play a role in biofilm formation and virulence of A. baumannii. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Thallium bromide iodide crystal acoustic anisotropy examination.

    Science.gov (United States)

    Mantsevich, S N

    2017-03-01

    Thallium bromide iodide crystal also known as KRS-5 is the well known material used in far infrared radiation applications for optical windows and lenses fabrication. The main advantage of this material is the transparency in wide band of wavelengths from 0.53 to 50μm. Despite such advantages as transparency and large acousto-optic figure of merit values, KRS-5 is rarely used in acousto-optics. Nevertheless this material seems to be promising for far infrared acousto-optic applications. The acoustic and acousto-optic properties of KRS-5 needed for the full use in optoelectronics are not well understood to date. In this paper the detailed examination of thallium bromide iodide crystal acoustic properties is presented. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Health profiles of methyl bromide applicators in greenhouses in Turkey.

    Science.gov (United States)

    Akca, Ergonen Toprak; Serpil, Salacin; Sezer, Uysal; Ozlem, Eminoglu; Ayşe, Gelal; Canan, Coker; Hakan, Baydur; Ozgur, Karcioglu; Banu, Onvural; Hulya, Guven

    2009-08-01

    Methyl bromide is a toxic substance that has hazardous effects on human health with acute and chronic exposure. Our previous study showed that methyl bromide applicators frequently use large amounts of methyl bromide haphazardly in greenhouses in the prefectures of Narlidere and Balcova in the Aegean city of Izmir. This study aims to evaluate the health conditions of these workers. Our previous study showed that there are 38 methyl bromide applicators in our study area. After the informed consent of methyl bromide applicators was obtained, a questionnaire was used for a survey of demography and symptoms. Each subject was examined before and after application of the compound. Blood and urine samples were collected and stored. Blood samples were analysed for methyl bromide and bromide ion, kidney and liver function tests and lipid profile. The age range of subjects was 19 to 53 years (mean age: 41 +/- 8.57). This study showed that methyl bromide applicators use large amounts of methyl bromide disregarding legal regulations and that some of them had nonspecific complaints. Subjects had been working as methyl bromide applicators for approximately 9.7 +/- 4.15 years. A total of 69.7% of methyl bromide applicators reported that they did not use protective equipment while 33.3% of them had a history of acute methyl bromide intoxication. A statistically significant relationship was found between the usage of protective equipment and the level of blood bromide ion in the blood (P <0.05). Usage of methyl bromide, training, screening and follow-up of applicators must be rigorously controlled in accordance with national legal arrangements and international protocols. Greater efforts are required in the implementation of controls to achieve the targets set by the legal regulations and to ensure continual improvement in the limitation of the risks of this environmental hazard.

  16. Aclidinium bromide for the treatment of chronic obstructive pulmonary disease.

    Science.gov (United States)

    Stone, Lowell E; Skelley, Jessica W; Kyle, Jeffrey A; Elmore, Lindsey K

    2014-03-01

    The safety and efficacy of the second U.S.-approved long-acting inhaled anticholinergic for controlling bronchospasm in patients with chronic obstructive pulmonary disease (COPD) are reviewed. Aclidinium bromide (Tudorza, Forest Pharmaceuticals) is indicated for long-term maintenance therapy for COPD-associated bronchospasm. It is marketed as a 60-dose metered-dose inhaler to be used twice daily. In Phase II and III clinical trials involving a total of more than 3000 patients, daily use of aclidinium bromide was found to significantly improve selected key indicators of lung function (trough values for forced expiratory volume at one second [FEV1] and other FEV1 outcome measures) compared with placebo use. Other benefits of aclidinium bromide therapy, including a significant reduction in nighttime COPD symptoms, were demonstrated for up to one year. However, aclidinium bromide has not been consistently demonstrated to be more effective than the other currently available long-acting inhaled anticholinergic, tiotropium bromide. Furthermore, the clinical trials indicated no significant difference between aclidinium bromide and tiotropium bromide with regard to rates of systemic adverse effects. For some patients, aclidinium bromide may offer advantages over tiotropium bromide (e.g., a faster time to peak FEV1, lower cost of therapy). Aclidinium bromide is an inhaled anticholinergic that improves lung function measures in patients with COPD. The most common adverse effects during clinical trials of the drug were headache, nasopharyngitis, and cough, none of which occurred at significantly higher rates than were seen with placebo use.

  17. Inactivation of Efflux Pumps Abolishes Bacterial Biofilm Formation▿

    OpenAIRE

    Kvist, Malin; Hancock, Viktoria; Klemm, Per

    2008-01-01

    Bacterial biofilms cause numerous problems in health care and industry; notably, biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Bacteria rely on efflux pumps to get rid of toxic substances. We discovered that efflux pumps are highly active in bacterial biofilms, thus making efflux pumps attractive targets for antibiofilm measures. A number of efflux pump ...

  18. New methods for the identification of efflux mediated MDR bacteria, genetic assessment of regulators and efflux pump constituents, characterization of efflux systems and screening for inhibitors of efflux pumps

    DEFF Research Database (Denmark)

    Viveiros, M; Martins, M; Couto, I

    2008-01-01

    We have developed a number of methods that identify efflux pump mediated multi-drug resistant bacteria, characterize efflux systems and screen for inhibitors of efflux pumps. These approaches were complemented by the quantification of the expression of genes that regulate and code for constituent...

  19. CO2 efflux from cleared mangrove peat.

    Directory of Open Access Journals (Sweden)

    Catherine E Lovelock

    Full Text Available BACKGROUND: CO(2 emissions from cleared mangrove areas may be substantial, increasing the costs of continued losses of these ecosystems, particularly in mangroves that have highly organic soils. METHODOLOGY/PRINCIPAL FINDINGS: We measured CO(2 efflux from mangrove soils that had been cleared for up to 20 years on the islands of Twin Cays, Belize. We also disturbed these cleared peat soils to assess what disturbance of soils after clearing may have on CO(2 efflux. CO(2 efflux from soils declines from time of clearing from ∼10,600 tonnes km(-2 year(-1 in the first year to 3000 tonnes km(2 year(-1 after 20 years since clearing. Disturbing peat leads to short term increases in CO(2 efflux (27 umol m(-2 s(-1, but this had returned to baseline levels within 2 days. CONCLUSIONS/SIGNIFICANCE: Deforesting mangroves that grow on peat soils results in CO(2 emissions that are comparable to rates estimated for peat collapse in other tropical ecosystems. Preventing deforestation presents an opportunity for countries to benefit from carbon payments for preservation of threatened carbon stocks.

  20. Kinetics and Product Channels in Combustion Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Hershberger, John F. [North Dakota State Univ., Fargo, ND (United States)

    2017-02-28

    We report study of the chemical kinetics and/or photochemistry of several chemical reactions of potential interest in understanding the gas phase combustion chemistry of nitrogen-containing molecules. Studies completed during the final grant period include determination of quantum yields of the photolysis of HCNO, fulminic acid, a kinetics and product channel study of the reaction of CN radicals with methyl bromide, and study of the products of the reaction of hydroxymethyl radical with nitric oxide.

  1. Kinetics of bromochloramine formation and decomposition.

    Science.gov (United States)

    Luh, Jeanne; Mariñas, Benito J

    2014-01-01

    Batch experiments were performed to study the kinetics of bromochloramine formation and decomposition from the reaction of monochloramine and bromide ion. The effects of pH, initial monochloramine and bromide ion concentrations, phosphate buffer concentration, and excess ammonia were evaluated. Results showed that the monochloramine decay rate increased with decreasing pH and increasing bromide ion concentration, and the concentration of bromochloramine increased to a maximum before decreasing gradually. The maximum bromochloramine concentration reached was found to decrease with increasing phosphate and ammonia concentrations. Previous models in the literature were not able to capture the decay of bromochloramine, and therefore we proposed an extended model consisting of reactions for monochloramine autodecomposition, the decay of bromamines in the presence of bromide, bromochloramine formation, and bromochloramine decomposition. Reaction rate constants were obtained through least-squares fitting to 11 data sets representing the effect of pH, bromide, monochloramine, phosphate, and excess ammonia. The reaction rate constants were then used to predict monochloramine and bromochloramine concentration profiles for all experimental conditions tested. In general, the modeled lines were found to provide good agreement with the experimental data under most conditions tested, with deviations occurring at low pH and high bromide concentrations.

  2. Development of copper bromide laser master oscillator power ...

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... Development of master oscillator power amplifier (MOPA) system of copper bromide laser (CBL) operating at 110 W average power is reported. The spectral distribution of power at green (510.6 nm) and yellow (578.2 nm) components in the output of a copper bromide laser is studied as a function of ...

  3. response of farmers to technological transfer in the methyl bromide ...

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    2012-08-30

    Aug 30, 2012 ... BROMIDE PHASE-OUT PROGRAMME IN ZIMBABWE: THE FLOATING TRAY SYSTEM ... phase out the last 182 tonnes of methyl bromide then used in tobacco seedling production. ... le système du plateau flottant bien que 61 % étaientinformés de la technologie et ne pouvaient pas l'utiliser, en avançant ...

  4. Hole conduction in pure and doped lead bromide crystals

    NARCIS (Netherlands)

    Schoonman, J.

    The conductivity of pure and doped lead bromide was measured in a bromine atmosphere in the temperature region 25–200°C. The defect chemistry of nonstoichiometric lead bromide is presented. The hole mobility was derived from the time dependent change in the conductivity after admission/removal of

  5. Potassium bromide, KBr/ ε: New Force Field

    Science.gov (United States)

    Fuentes-Azcatl, Raúl; Barbosa, Marcia C.

    2018-02-01

    We propose a new force field for the Potassium Bromide, the KBr/ ε. The crystal density and structure, as well as, the density, the viscosity and the dielectric constant of the solution in water were computed and compared with the experiments and other atomistic models. Next, the transferability of the KBr/ ε and of the NaCl/ ε models is verified by creating the KCl/ ε and the NaBr/ ε models. The strategy was to employ the same parameters obtained for the NaCl/ ε and for the KBr/ ε force fields for the building up of the KCl/ ε and the NaBr/ ε models . The thermodynamic and dynamic properties of these two new models were compared with the experimental

  6. Hydrogen-bond interactions in morpholinium bromide

    Directory of Open Access Journals (Sweden)

    Alvaro S. de Sousa

    2011-10-01

    Full Text Available In the title compound, C4H10NO+·Br−, which was synthesized by dehydration of diethanolamine with HBr, morpholinium and bromide ions are linked into chains by N—H...Br hydrogen bonds describing a C21(4 graph-set motif. Weaker bifurcated N—H...Br interactions join centrosymmetrically related chains through alternating binary graph-set R42(8 and R22(4 motifs, to form ladders along [100]. In addition, C—H...O interactions between centrosymmetric morpholinium cations link ladders, via R^2_2(8 motifs, to yield sheets parallel to (101, which in turn are crosslinked by weak C—H...O interactions, related across a glide plane, to form a three-dimensional network.

  7. Potent and selective mediators of cholesterol efflux

    Energy Technology Data Exchange (ETDEWEB)

    Bielicki, John K; Johansson, Jan

    2015-03-24

    The present invention provides a family of non-naturally occurring polypeptides having cholesterol efflux activity that parallels that of full-length apolipoproteins (e.g., Apo AI and Apo E), and having high selectivity for ABAC1 that parallels that of full-length apolipoproteins. The invention also provides compositions comprising such polypeptides, methods of identifying, screening and synthesizing such polypeptides, and methods of treating, preventing or diagnosing diseases and disorders associated with dyslipidemia, hypercholesterolemia and inflammation.

  8. CO₂ efflux from shrimp ponds in Indonesia.

    Directory of Open Access Journals (Sweden)

    Frida Sidik

    Full Text Available The conversion of mangrove forest to aquaculture ponds has been increasing in recent decades. One of major concerns of this habitat loss is the release of stored 'blue' carbon from mangrove soils to the atmosphere. In this study, we assessed carbon dioxide (CO₂ efflux from soil in intensive shrimp ponds in Bali, Indonesia. We measured CO₂ efflux from the floors and walls of shrimp ponds. Rates of CO₂ efflux within shrimp ponds were 4.37 kg CO₂ m⁻² y⁻¹ from the walls and 1.60 kg CO₂ m⁻² y⁻¹ from the floors. Combining our findings with published data of aquaculture land use in Indonesia, we estimated that shrimp ponds in this region result in CO₂ emissions to the atmosphere between 5.76 and 13.95 Tg y⁻¹. The results indicate that conversion of mangrove forests to aquaculture ponds contributes to greenhouse gas emissions that are comparable to peat forest conversion to other land uses in Indonesia. Higher magnitudes of CO₂ emission may be released to atmosphere where ponds are constructed in newly cleared mangrove forests. This study indicates the need for incentives that can meet the target of aquaculture industry without expanding the converted mangrove areas, which will lead to increased CO₂ released to atmosphere.

  9. The putative drug efflux systems of the Bacillus cereus group.

    Science.gov (United States)

    Hassan, Karl A; Fagerlund, Annette; Elbourne, Liam D H; Vörös, Aniko; Kroeger, Jasmin K; Simm, Roger; Tourasse, Nicolas J; Finke, Sarah; Henderson, Peter J F; Økstad, Ole Andreas; Paulsen, Ian T; Kolstø, Anne-Brit

    2017-01-01

    The Bacillus cereus group of bacteria includes seven closely related species, three of which, B. anthracis, B. cereus and B. thuringiensis, are pathogens of humans, animals and/or insects. Preliminary investigations into the transport capabilities of different bacterial lineages suggested that genes encoding putative efflux systems were unusually abundant in the B. cereus group compared to other bacteria. To explore the drug efflux potential of the B. cereus group all putative efflux systems were identified in the genomes of prototypical strains of B. cereus, B. anthracis and B. thuringiensis using our Transporter Automated Annotation Pipeline. More than 90 putative drug efflux systems were found within each of these strains, accounting for up to 2.7% of their protein coding potential. Comparative analyses demonstrated that the efflux systems are highly conserved between these species; 70-80% of the putative efflux pumps were shared between all three strains studied. Furthermore, 82% of the putative efflux system proteins encoded by the prototypical B. cereus strain ATCC 14579 (type strain) were found to be conserved in at least 80% of 169 B. cereus group strains that have high quality genome sequences available. However, only a handful of these efflux pumps have been functionally characterized. Deletion of individual efflux pump genes from B. cereus typically had little impact to drug resistance phenotypes or the general fitness of the strains, possibly because of the large numbers of alternative efflux systems that may have overlapping substrate specificities. Therefore, to gain insight into the possible transport functions of efflux systems in B. cereus, we undertook large-scale qRT-PCR analyses of efflux pump gene expression following drug shocks and other stress treatments. Clustering of gene expression changes identified several groups of similarly regulated systems that may have overlapping drug resistance functions. In this article we review current

  10. Liquid-phase oxidation of 2,3-dimethylbenzoic acid (DMBA) catalyzed by cobalt and bromide salts

    Energy Technology Data Exchange (ETDEWEB)

    Perelman, E.B.; Malykh, G.A.; Kharlampovich, G.D.; Moskovskikh, V.V.

    1978-01-01

    The kinetics of liquid-phase oxidation of 2,3-dimethylbenzoic acid (DMBA) by oxygen catalyzed by cobalt and bromide salts (i.e., cobalt acetate tetrahydrate and cobalt bromide hexahydrate in acetic acid solution) was studied chromatographically, and the optimum conditions for the formation of hemimellitic (1,2,3-tricarboxylic) acid (TCA) were determined (i.e., 105/sup 0/C, 0.2 g-ion cobalt per mole, 1:1 bromide to cobalt ion ratio, 1:10 DMBA to acetic acid ratio, and 10 l./min/l. of feed oxygen consumption). Under these conditions, the oxidation occurred without induction period, and over 90% by wt DMBA conversion with 70% TCA yield was achieved. If cobalt acetate or cobalt bromide were used individually, the process had very large induction times (i.e., 3-4 hr). A two-stage reaction mechanism involves 2-methylisophthalic acid (MIPA) and 3-methylphthalic acid (in smaller amounts) as intermediates. At 0.1 g-ion cobalt per mole, MIPA is the main product with approx. 70% yield. Apparently, the initial reaction stage is oxygen activation via the formation of monobromide complexes of catalyst, DMBA, and oxygen. Chromatograph and graphs.

  11. Growth and Characterization of Tetraphenylphosphonium Bromide Crystal

    Directory of Open Access Journals (Sweden)

    Guangqiang Wang

    2017-05-01

    Full Text Available Multiple-phenyl phosphorous compounds are a group of chemical materials that have been used as reactants, pharmaceutical intermediates, extractants, and catalysts in organic synthetic reactions. However, the crystal growth of bulk crystals of multiple-phenyl phosphorous compounds, which may expand their applications in photonics technology, have been largely overlooked. In this article, the crystal growth of tetraphenylphosphonium bromide (TPPB has been studied in organic solvents and water. The crystal structures and crystallization features are analyzed by X-ray diffraction data. By a slow temperature-lowering method, a single-crystal of TPPB (2H2O with the size of 27 × 20 × 20 mm3 has been obtained in water. The basic thermal and optical properties were characterized. We find that the TPPB (2H2O crystal shows excellent transparent property in the near-IR region. Large Raman shifts and strong Raman scattering intensity indicate that TPPB is a potential candidate in Raman-scattering-based nonlinearity applications.

  12. Chloride, bromide and iodide scintillators with europium

    Science.gov (United States)

    Zhuravleva, Mariya; Yang, Kan

    2016-09-27

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  13. Inactivation of Efflux Pumps Abolishes Bacterial Biofilm Formation

    DEFF Research Database (Denmark)

    Kvist, Malin; Hancock, Viktoria; Klemm, Per

    2008-01-01

    Bacterial biofilms cause numerous problems in health care and industry; notably, biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Bacteria rely on efflux pumps...... to get rid of toxic substances. We discovered that efflux pumps are highly active in bacterial biofilms, thus making efflux pumps attractive targets for antibiofilm measures. A number of efflux pump inhibitors (EPIs) are known. EPIs were shown to reduce biofilm formation, and in combination they could...

  14. Methyl Bromide Commodity Fumigation Buffer Zone Lookup Tables

    Science.gov (United States)

    Product labels for methyl bromide used in commodity and structural fumigation include requirements for buffer zones around treated areas. The information on this page will allow you to find the appropriate buffer zone for your planned application.

  15. Disinfection byproduct regulatory compliance surrogates and bromide-associated risk.

    Science.gov (United States)

    Kolb, Chelsea; Francis, Royce A; VanBriesen, Jeanne M

    2017-08-01

    Natural and anthropogenic factors can alter bromide concentrations in drinking water sources. Increasing source water bromide concentrations increases the formation and alters the speciation of disinfection byproducts (DBPs) formed during drinking water treatment. Brominated DBPs are more toxic than their chlorinated analogs, and thus have a greater impact on human health. However, DBPs are regulated based on the mass sum of DBPs within a given class (e.g., trihalomethanes and haloacetic acids), not based on species-specific risk or extent of bromine incorporation. The regulated surrogate measures are intended to protect against not only the species they directly represent, but also against unregulated DBPs that are not routinely measured. Surrogates that do not incorporate effects of increasing bromide may not adequately capture human health risk associated with drinking water when source water bromide is elevated. The present study analyzes trihalomethanes (THMs), measured as TTHM, with varying source water bromide concentrations, and assesses its correlation with brominated THM, TTHM risk and species-specific THM concentrations and associated risk. Alternative potential surrogates are evaluated to assess their ability to capture THM risk under different source water bromide concentration conditions. The results of the present study indicate that TTHM does not adequately capture risk of the regulated species when source water bromide concentrations are elevated, and thus would also likely be an inadequate surrogate for many unregulated brominated species. Alternative surrogate measures, including THM3 and the bromodichloromethane concentration, are more robust surrogates for species-specific THM risk at varying source water bromide concentrations. Copyright © 2017. Published by Elsevier B.V.

  16. Synthesis and Characterization of Mercuric Bromide-Phenothiazine Complexes

    OpenAIRE

    Vidisha A. Alwani; Kishore Cholkar; Ananth A Nayak; Netkal M. Made Gowda

    2014-01-01

    N-alkylphenothiazines (NAPTZs) are biologically active heterocyclic compounds that find extensive applications in the field of medicine. In the pharmaceutical industry, they are used as psychotherapeutic, antiemetic, and antihistaminic drugs. In this study, complexation reactions of mercuric bromide with NAPTZs as principal ligands have been investigated in MeOH medium. Five mercuric bromide complexes of the NAPTZ ligands namely, chlorpromazine hydrochloride (CP.HCl), promethazine hydrochl...

  17. Zinc Bromide Flow Battery Installation for Islanding and Backup Power

    Science.gov (United States)

    2016-09-18

    FINAL REPORT Zinc Bromide Flow Battery Installation for Islanding and Backup Power ESTCP Project EW-201242 SEPTEMBER 2016 Ryan...Bromide (Zn/Br) Flow Battery -based Energy Storage System (ESS) at the Marine Corps Air Station (MCAS) Miramar. The effort integrates an innovative Zn...Zn/Br) Flow Battery -based Energy Storage System (ESS) at the Marine Corps Air Station (MCAS) Miramar. The effort integrates an innovative Zn/Br

  18. Reaction of lithium diethylamide with an alkyl bromide and alkyl benzenesulfonate: origins of alkylation, elimination, and sulfonation.

    Science.gov (United States)

    Gupta, Lekha; Ramírez, Antonio; Collum, David B

    2010-12-17

    A combination of NMR, kinetic, and computational methods are used to examine reactions of lithium diethylamide in tetrahydrofuran (THF) with n-dodecyl bromide and n-octyl benzenesulfonate. The alkyl bromide undergoes competitive S(N)2 substitution and E2 elimination in proportions independent of all concentrations except for a minor medium effect. Rate studies show that both reactions occur via trisolvated-monomer-based transition structures. The alkyl benzenesulfonate undergoes competitive S(N)2 substitution (minor) and N-sulfonation (major) with N-sulfonation promoted at low THF concentrations. The S(N)2 substitution is shown to proceed via a disolvated monomer suggested computationally to involve a cyclic transition structure. The dominant N-sulfonation follows a disolvated-dimer-based transition structure suggested computationally to be a bicyclo[3.1.1] form. The differing THF and lithium diethylamide orders for the two reactions explain the observed concentration-dependent chemoselectivities.

  19. Catalytic Effect of Cetyltrimethylammonium Bromide on the Oxidation of Triethylene glycol by Chloramine-T in Acidic Medium

    Directory of Open Access Journals (Sweden)

    Vandana Sharma

    2008-01-01

    Full Text Available The kinetics and mechanism of cetyltrimethylammonium bromide catalyzed oxidation of triethylene glycol [2,2'-ethylene diqxybis(ethanol] by chloramine-T in acidic acid medium have been investigated. The reaction is first order dependence on chloramine-T and fractional order for triethylene glycol with excess concentration of other reactants. The catalytic effect due to cetyletrimethylammonium bromide has been studied. The small salt effect and increase in the reaction rate with increasing dielectric constant suggest the involvement of neutral molecule in the rate-determining step. The addition of p-toluene sulfonamide retards the reaction rate. The effect of chloride ion on the reaction also studied. The effect of temperature on the reaction has been investigated in the temperature range 313-333K and thermodynamic parameters were calculated from the Arrhenious plot. A tentative mechanism consistent with the experimental results has been proposed.

  20. Detection of efflux pump activity among clinical isolates of ...

    African Journals Online (AJOL)

    Purpose: To detect efflux pump activity (EPA) and screening a suspected efflux pump inhibitor (EPI) [1-. (3-(trifluoromethyl)benzyl]-piperazine (TFMBP)], which could help in reducing multi-drug resistance. (MDR). Methods: Eighteen isolates, viz, 14 S. aureus, 2 S. lentus, 1 S. xylosus and 1 Micrococcus species from various ...

  1. Detection of efflux pump activity among clinical isolates of ...

    African Journals Online (AJOL)

    Purpose: To detect efflux pump activity (EPA) and screening a suspected efflux pump inhibitor (EPI) [1- (3-(trifluoromethyl)benzyl]-piperazine (TFMBP)], which could help in reducing multi-drug resistance (MDR). Methods: Eighteen isolates, viz, 14 S. aureus, 2 S. lentus, 1 S. xylosus and 1 Micrococcus species from various ...

  2. In-silico identification and phylogenetic analysis of auxin efflux ...

    African Journals Online (AJOL)

    The phytohormone auxin is crucial for plant growth and development. Transportation and distribution of auxin throughout the plant is very important to maintain the auxin homeostasis. Auxin efflux carrier genes play significant roles in auxin transport. In this study, we identified 12 auxin efflux carrier genes from the Setaria ...

  3. Efflux systems in bacteria and their metabolic engineering applications.

    Science.gov (United States)

    Jones, Christopher M; Hernández Lozada, Néstor J; Pfleger, Brian F

    2015-11-01

    The production of valuable chemicals from metabolically engineered microbes can be limited by excretion from the cell. Efflux is often overlooked as a bottleneck in metabolic pathways, despite its impact on alleviating feedback inhibition and product toxicity. In the past, it has been assumed that endogenous efflux pumps and membrane porins can accommodate product efflux rates; however, there are an increasing number of examples wherein overexpressing efflux systems is required to improve metabolite production. In this review, we highlight specific examples from the literature where metabolite export has been studied to identify unknown transporters, increase tolerance to metabolites, and improve the production capabilities of engineered bacteria. The review focuses on the export of a broad spectrum of valuable chemicals including amino acids, sugars, flavins, biofuels, and solvents. The combined set of examples supports the hypothesis that efflux systems can be identified and engineered to confer export capabilities on industrially relevant microbes.

  4. Intranasal ipratropium bromide for the common cold.

    Science.gov (United States)

    AlBalawi, Zaina H; Othman, Sahar S; Alfaleh, Khalid

    2013-06-19

    The common cold is one of the most common illnesses in humans and constitutes an economic burden both in terms of productivity and expenditure for treatment. There is no proven cure for the common cold and symptomatic relief is the mainstay of treatment. The use of intranasal ipratropium bromide (IB) has been addressed in several studies and might prove an effective treatment for the common cold. To determine the effect of IB versus placebo or no treatment on severity of rhinorrhoea and nasal congestion in children and adults with the common cold. Subjective overall improvement was another primary outcome and side effects (for example, dry mucous membranes, epistaxis and systemic anticholinergic effects) were reported as a secondary outcome. In this updated review we searched CENTRAL 2013, Issue 3, MEDLINE (1950 to March week 4, 2013), MEDLINE in-process and other non-indexed citations (8 April 2013), EMBASE (1974 to April 2013), AMED (1985 to April 2013), Biosis (1974 to February 2011) and LILACS (1985 to April 2013). Randomised controlled trials (RCTs) comparing IB to placebo or no treatment in children and adults with the common cold. Two review authors independently extracted data and assessed trial quality. We used a standardised form to extract relevant data and we contacted trial authors for additional information. Seven trials with a total of 2144 participants were included. Four studies (1959 participants) addressed subjective change in severity of rhinorrhoea. All studies were consistent in reporting statistically significant changes in favour of IB. Nasal congestion was reported in four studies and was found to have no significant change between the two groups. Two studies found a positive response in the IB group for the global assessment of overall improvement. Side effects were more frequent in the IB group, odds ratio (OR) 2.09 (95% confidence interval (CI) 1.40 to 3.11). Commonly encountered side effects included nasal dryness, blood tinged mucus

  5. Effect of Mo on pitting corrosion of ferritic steels in bromide and chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, M. [Nippon Steel Corp., Futtsu Chiba (Japan). Steel Research Lab; Isaacs, H.S. [Brookhaven National Lab., Upton, NY (United States)

    1997-12-01

    A model for pitting corrosion of stainless steels, independent of changes of passive film properties, was tested using Fe-18%Cr-x%Mo alloys in bromide and chlorine solutions. In 1M LiCl the pitting potential improved from {minus}50 mV{sub sce} to about 1200 mV{sub sce} on increasing Mo from 2% to 10%. In 1M LiBr the pitting potential increased from 125 to only 560 mV{sub sce}. Active dissolution kinetics of these steels in saturated solutions in a simulated pit were measured. Tafel lines for dissolution moved to more noble potentials with increases in Mo, indicating Mo inhibited dissolution rates. The potential increases were found to be equal to the increases in pitting potential for both halides. Agreement was interpreted in terms maintaining high halide concentrations in the pit by high rates of active metal dissolution. Bromide was less effective suggesting it interacted with Mo adsorbed on the dissolving surface.

  6. Study of the Reaction 2-(p-Nitrophenylethyl Bromide + OH− in Dimeric Micellar Solutions

    Directory of Open Access Journals (Sweden)

    María Luisa Moyá

    2011-11-01

    Full Text Available The dehydrobromination reaction 2-(p-nitrophenylethyl bromide + OH− was investigated in several alkanediyl-a-w-bis(dodecyldimethylammonium bromide, 12-s-12,2Br− (with s = 2, 3, 4, 5, 6, 8, 10, 12 micellar solutions, in the presence of NaOH 5 × 10−3 M. The kinetic data were quantitatively rationalized within the whole surfactant concentration range by using an equation based on the pseudophase ion-exchange model and taking the variations in the micellar ionization degree caused by the morphological transitions into account. The agreement between the theoretical and the experimental data was good in all the dimeric micellar media studied, except for the 12-2-12,2Br− micellar solutions. In this case, the strong tendency to micellar growth shown by the 12-2-12,2Br− micelles could be responsible for the lack of accordance. Results showed that the dimeric micelles accelerate the reaction more than two orders of magnitude as compared to water.

  7. Bifurcation kinetics of drug uptake by Gram-negative bacteria.

    Science.gov (United States)

    Westfall, David A; Krishnamoorthy, Ganesh; Wolloscheck, David; Sarkar, Rupa; Zgurskaya, Helen I; Rybenkov, Valentin V

    2017-01-01

    Cell envelopes of many bacteria consist of two membranes studded with efflux transporters. Such organization protects bacteria from the environment and gives rise to multidrug resistance. We report a kinetic model that accurately describes the permeation properties of this system. The model predicts complex non-linear patterns of drug uptake complete with a bifurcation, which recapitulate the known experimental anomalies. We introduce two kinetic parameters, the efflux and barrier constants, which replace those of Michaelis and Menten for trans-envelope transport. Both compound permeation and efflux display transitions, which delineate regimes of efficient and inefficient efflux. The first transition is related to saturation of the transporter by the compound and the second one behaves as a bifurcation and involves saturation of the outer membrane barrier. The bifurcation was experimentally observed in live bacteria. We further found that active efflux of a drug can be orders of magnitude faster than its diffusion into a cell and that the efficacy of a drug depends both on its transport properties and therapeutic potency. This analysis reveals novel physical principles in the behavior of the cellular envelope, creates a framework for quantification of small molecule permeation into bacteria, and should invigorate structure-activity studies of novel antibiotics.

  8. Resistance to Antimicrobials Mediated by Efflux Pumps in Staphylococcus aureus

    Science.gov (United States)

    Costa, Sofia S.; Junqueira, Elisabete; Palma, Cláudia; Viveiros, Miguel; Melo-Cristino, José; Amaral, Leonard; Couto, Isabel

    2013-01-01

    Resistance mediated by efflux has been recognized in Staphylococcus aureus in the last few decades, although its clinical relevance has only been recognized recently. The existence of only a few studies on the individual and overall contribution of efflux to resistance phenotypes associated with the need of well-established methods to assess efflux activity in clinical isolates contributes greatly to the lack of solid knowledge of this mechanism in S. aureus. This study aims to provide information on approaches useful to the assessment and characterization of efflux activity, as well as contributing to our understanding of the role of efflux to phenotypes of antibiotic resistance and biocide tolerance in S. aureus clinical isolates. The results described show that efflux is an important contributor to fluoroquinolone resistance in S. aureus and suggest it as a major mechanism in the early stages of resistance development. We also show that efflux plays an important role on the reduced susceptibility to biocides in S. aureus, strengthening the importance of this long neglected resistance mechanism to the persistence and proliferation of antibiotic/biocide-resistant S. aureus in the hospital environment. PMID:27029294

  9. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants

    Directory of Open Access Journals (Sweden)

    Paula Blanco

    2016-02-01

    Full Text Available Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics.

  10. Crystallization and preliminary X-ray diffraction analysis of the multidrug efflux transporter NorM from Neisseria gonorrhoeae

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chih-Chia [Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011 (United States); Long, Feng [Molecular, Cellular and Developmental Biology Interdepartmental Graduate Program, Iowa State University, Ames, IA 50011 (United States); McDermott, Gerry [Department of Anatomy, School of Medicine, University of California, San Francisco, CA 94143 (United States); Shafer, William M. [Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322 (United States); Laboratories of Microbial Pathogenesis, VA Medical Center, Decatur, Georgia 30033 (United States); Yu, Edward W., E-mail: ewyu@iastate.edu [Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011 (United States); Molecular, Cellular and Developmental Biology Interdepartmental Graduate Program, Iowa State University, Ames, IA 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)

    2008-04-01

    The multidrug efflux transporter NorM from N. gonorrhoeae has been crystallized and X-ray diffraction data have been collected to a resolution of 6.5 Å. The crystallization and preliminary X-ray data analysis of the NorM multidrug efflux pump produced by Neisseria gonorrhoeae are reported. NorM is a cytoplasmic membrane protein that consists of 459 amino-acid residues. It is a member of the recently classified multidrug and toxic compound extrusion (MATE) family of transporters and recognizes a number of cationic toxic compounds such as ethidium bromide, acriflavin, 2-N-methylellipticinium and ciprofloxacin. Recombinant NorM protein was expressed in Escherichia coli and purified by metal-affinity and gel-filtration chromatography. The protein was crystallized using hanging-drop vapor diffusion. X-ray diffraction data were collected from cryocooled crystals at a synchrotron light source. The best crystal diffracted anisotropically to 3.8 Å and diffraction data were complete to 6.5 Å resolution. The space group was determined to be C2, with unit-cell parameters a = 81.5, b = 164.4, c = 111.5 Å.

  11. Microvilli Morphology Can Affect Efflux Active P-Glycoprotein in Confluent MDCKII -hMDR1-NKI and Caco-2 Cell Monolayers.

    Science.gov (United States)

    Meng, Zhou; Le Marchand, Sylvain; Agnani, Deep; Szapacs, Matthew; Ellens, Harma; Bentz, Joe

    2017-02-01

    From fits of drug transport kinetics across confluent MDCKII-hMDR1-NKI and Caco-2 cell monolayers we estimated the levels of efflux active P-glycoprotein (P-gp) in these two cell lines (companion paper). In the present work, we compared the efflux active P-gp number to the total P-gp level, using liquid chromatography-tandem mass spectrometry, and showed that in Caco-2 cells total P-gp is about 10-fold greater than efflux active P-gp, whereas in MDCKII-hMDR1-NKI cells these values are within twofold. We further visualized the microvilli in MDCKII-hMDR1-NKI and Caco-2 cells using three-dimensional structured illumination super-resolution microscopy and found that the microvilli in Caco-2 cells are taller and more densely packed than those in MDCK-hMDR1-NKI cells. We hypothesized over 10 years ago that only P-gp at the tips of the microvilli contribute significantly to efflux activity, whereas the remaining P-gp are involved in a futile cycle of efflux of amphipathic drugs from the microvillus membrane, followed by their reabsorption into the same or nearby microvillous membranes. The difference between the levels of total and efflux active P-gp in Caco-2 cells can be explained by the more densely packed microvilli in Caco-2 cells, which would lead to a substantial fraction of P-gp not contributing to final release of drug into the apical chamber. Our results suggest that the effect of microvilli morphology differences between in vitro and in vivo systems must be considered when scaling transporter activity for efflux transporters of amphipathic compounds, for example, P-gp. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

  12. Clinical potential of aclidinium bromide in chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Zhong J

    2014-06-01

    Full Text Available Jun Zhong, Michael Roth Pneumology and Pulmonary Cell Research, Department of Biomedicine and Internal Medicine, University Hospital Basel, Basel, Switzerland Abstract: Chronic obstructive pulmonary disease (COPD is increasing worldwide and is predicted to become the third most frequent cause of death by 2030. Muscarinic receptor antagonists, alone or in combination with long-acting ß2-agonists, are frequently used for COPD therapy. Aclidinium bromide is a novel muscarinic receptor antagonist, and clinical studies indicate that its metabolism is more rapid than that of other muscarinic receptor inhibitors, so systemic side effects are expected to occur less frequently. Aclidinium bromide is well tolerated, and when compared with other muscarinic receptor antagonists, the drug achieves better control of lung function, especially night-time symptoms in COPD patients. This review summarizes the safety profile and side effects reported by recent clinical studies using aclidinium bromide alone. Keywords: aclidinium, tiotropium, side effects, clinical safety

  13. Water- Lithium Bromide-γ- Butyrolactone Absorption Refrigerating Machine

    Science.gov (United States)

    Iyoki, Shigeki; Uemura, Tadashi

    This investigation was carried out in order to find corrosion inhibitors which would be effective in controlling the corrosion for the water-lithium bromide-γ-butyrolactone (20 moles water/1 mole γ-butyrolactone) absorption refrigerating machine. The experiments were carried out on continuous boiling test, intermittent boiling test and galvanic corrosion test with the use of organic inhibitors and inorganic inhibitors in γ-butyrolactone aqueous solution of lithium bromide. The metals used in these corrosion tests were mainly SS 41 and copper. From these experimental results, the most suitable corrosion inhibitors for SS 41 and copper in γ-butyrolactone aqueous solution of lithium bromide Were recognized to be benzotriazole, tolyltriazole and lithium molybdate.

  14. Biokinetic uptake and efflux of silver nanoparticles in Daphnia magna.

    Science.gov (United States)

    Zhao, Chun-Mei; Wang, Wen-Xiong

    2010-10-01

    Silver nanoparticles (AgNP) are widely used as antibacterial products, and there are increasing concerns for their potential environmental risks in aquatic ecosystems. The biokinetics of AgNP in aquatic organisms has not yet been determined. In the present study, we employed a radiotracer methodology to quantify the biokinetics of AgNP in a freshwater cladoceran Daphnia magna, including the uptake from water, dietary assimilation, and elimination of AgNP. We found that the uptake of AgNP was concentration dependent and governed by two phases. The uptake rate constant (k(u)) was 0.060 L/g/h at low AgNP concentrations (2, 10, and 40 μg/L), which was 4.3 times lower than that of the Ag free ion. At a higher AgNP concentration (160 and 500 μg/L), the uptake rate increased disproportionately, likely as a result of direct ingestion of these nanoparticles by the daphnids. When the AgNP were associated with the algal food, their dietary assimilation efficiency (AE) was in the range of 22-45%, which was much higher than the dietary assimilation of Ag quantified under the same food conditions. The efflux rate constants of AgNP in daphnids were also much lower than those of the Ag, again suggesting the difficulty of eliminating AgNP by the daphnids. Water excretion was the main elimination route for both AgNP and Ag, but a higher percentage of AgNP was lost through fecal production. Finally, we used a kinetic equation to compare the importance of aqueous and dietary uptake of AgNP using the quantified kinetic parameters. The biokinetic model showed that more than 70% of AgNP accumulated in the daphnids was through ingestion of algae, highlighting the importance of AgNP transport along the food chain. Our present study showed the unique characteristic of AgNP biokinetics and suggested that more attention should be paid to the dietborne AgNP toxicity in aquatic ecosystems.

  15. Efflux as a mechanism for drug resistance in Mycobacterium tuberculosis.

    Science.gov (United States)

    da Silva, Pedro Eduardo Almeida; Von Groll, Andrea; Martin, Anandi; Palomino, Juan Carlos

    2011-10-01

    Tuberculosis remains an important global public health problem, with an estimated prevalence of 14 million individuals with tuberculosis worldwide in 2007. Because antibiotic treatment is one of the main tools for tuberculosis control, knowledge of Mycobacterium tuberculosis drug resistance is an important component for the disease control strategy. Although several gene mutations in specific loci of the M. tuberculosis genome have been reported as the basis for drug resistance, additional resistance mechanisms are now believed to exist. Efflux is a ubiquitous mechanism responsible for intrinsic and acquired drug resistance in prokaryotic and eukaryotic cells. Mycobacterium tuberculosis presents one of the largest numbers of putative drug efflux pumps compared with its genome size. Bioinformatics as well as direct and indirect evidence have established relationships among drug efflux with intrinsic or acquired resistance in M. tuberculosis. This minireview describes the current knowledge on drug efflux in M. tuberculosis. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  16. Kinetic Typography

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Djonov, Emilia

    2014-01-01

    After discussing broad cultural drivers behind the development of kinetic typography, the chapter outlines an approach to analysing kinetic typography which is based on Halliday's theory of transitivity, as applied by Kress and Van Leeuwen to visual images....

  17. Sodium efflux in plant roots: what do we really know?

    Science.gov (United States)

    Britto, D T; Kronzucker, H J

    2015-08-15

    The efflux of sodium (Na(+)) ions across the plasma membrane of plant root cells into the external medium is surprisingly poorly understood. Nevertheless, Na(+) efflux is widely regarded as a major mechanism by which plants restrain the rise of Na(+) concentrations in the cytosolic compartments of root cells and, thus, achieve a degree of tolerance to saline environments. In this review, several key ideas and bodies of evidence concerning root Na(+) efflux are summarized with a critical eye. Findings from decades past are brought to bear on current thinking, and pivotal studies are discussed, both "purely physiological", and also with regard to the SOS1 protein, the only major Na(+) efflux transporter that has, to date, been genetically characterized. We find that the current model of rapid transmembrane sodium cycling (RTSC), across the plasma membrane of root cells, is not adequately supported by evidence from the majority of efflux studies. An alternative hypothesis cannot be ruled out, that most Na(+) tracer efflux from the root in the salinity range does not proceed across the plasma membrane, but through the apoplast. Support for this idea comes from studies showing that Na(+) efflux, when measured with tracers, is rarely affected by the presence of inhibitors or the ionic composition in saline rooting media. We conclude that the actual efflux of Na(+) across the plasma membrane of root cells may be much more modest than what is often reported in studies using tracers, and may predominantly occur in the root tips, where SOS1 expression has been localized. Copyright © 2015 Elsevier GmbH. All rights reserved.

  18. A Perspective on Efflux Transport Proteins in the Liver

    OpenAIRE

    Kock, K.; Brouwer, K. L. R.

    2012-01-01

    Detailed knowledge regarding the influence of hepatic transport proteins on drug disposition has advanced at a rapid pace over the past decade. Efflux transport proteins located in the basolateral and apical (canalicular) membranes of hepatocytes play an important role in the hepatic elimination of many endogenous and exogenous compounds, including drugs and metabolites. This review focuses on the role of these efflux transporters in hepatic drug excretion. The impact of these proteins as und...

  19. Glycosylation with Disarmed Glycosyl Bromides Promoted by Iodonium Ions

    DEFF Research Database (Denmark)

    Lanz, Gyrithe; Madsen, Robert

    2016-01-01

    Iodonium ions have been developed for activating glycosyl bromides in the coupling to glycosyl acceptors. The iodonium ions are generated from N-iodosuccinimide and a protic acid such as camphorsulfonic acid or triflic acid, where the latter gives the most reactive promoter system. The couplings ...

  20. Study of methyl bromide reactivity with human and mouse hemoglobin

    African Journals Online (AJOL)

    A study has been carried out on in-vitro reactivity of human and mouse hemoglobin spectrophotometrically at physiological pH, using different protein to reagent ratios. Hemoglobin side chains were modified with different concentrations of methyl bromide on agro-soil fumigant. To ascertain if the site of alkylation was the ...

  1. 7 CFR 305.6 - Methyl bromide fumigation treatment schedules.

    Science.gov (United States)

    2010-01-01

    ..., fumigation with methyl bromide for sapote fruit fly. Regulated citrus fruits originating inside an area... gas introduction, and allowed to run for at least 15 minutes. Fruit pulp temperature must be between 21.1 °C and 29.4 °C (70 °F and 85 °F). This temperature requirement refers to fruit pulp only and not...

  2. Effectiveness of hyoscine butyl bromide in shortening the first stage ...

    African Journals Online (AJOL)

    Background: Prolonged labour from cervical dystocia or stasis is one of the common indications for caesarean delivery. Hyoscine N-butyl bromide (HBB), an anticholinergic and antispasmodic drug, has been found effective in shortening the first stage of labour with no adverse effects on feto-maternal outcomes.

  3. Methyl bromide soil fumigation: effect on grass yields | MGW ...

    African Journals Online (AJOL)

    Annual herbage yields of grasses grown on sandy soils on Henderson Research Station seldom exceed 10 000 kg/ha dry matter, while on heavy clay soils yields of 18 000 kg/ha are consistently obtained with similar amounts of applied fertilizers. Keywords: methyl bromide|soils|fumigation|grasses|grass ...

  4. Ipratropium bromide delivered by metered-dose aerosol to infant ...

    African Journals Online (AJOL)

    Two methods of administration of ipratropium bromide (Atrovent; Boehringer Ingelheim) to wheezing children'< 25 months of age were compared: (i) the conventional nebulisation (15 children); and (ii) a metered-dose aerosol plus spacer and mask (MDA group, 17 children). The drug induced a significant and similar fall in ...

  5. Ipratropium bromide delivered by metered-dose aerosol to infant ...

    African Journals Online (AJOL)

    1990-08-21

    Aug 21, 1990 ... metered aerosol method compared with nebulisation of ipra- tropium bromide when given to wheezing infants and toddlers. The former method is convenient for primary health care facilities or home use, since it does not depend upon the availability of the nebuliser apparatus or a gas or electricity source.

  6. Solvent effects in the reaction between piperazine and benzyl bromide

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. The reaction between piperazine and benzyl bromide was studied conductometrically and the second order rate constants were computed. These rate constants determined in 12 different protic and aprotic solvents indicate that the rate of the reaction is influenced by electrophilicity (E), hydrogen bond donor ability ...

  7. Solvent effects in the reaction between piperazine and benzyl bromide

    Indian Academy of Sciences (India)

    The reaction between piperazine and benzyl bromide was studied conductometrically and the second order rate constants were computed. These rate constants determined in 12 different protic and aprotic solvents indicate that the rate of the reaction is influenced by electrophilicity (), hydrogen bond donor ability () and ...

  8. Erythromycin resistance by L4/L22 mutations and resistance masking by drug efflux pump deficiency

    Science.gov (United States)

    Lovmar, Martin; Nilsson, Karin; Lukk, Eliisa; Vimberg, Vladimir; Tenson, Tanel; Ehrenberg, Måns

    2009-01-01

    We characterized the effects of classical erythromycin resistance mutations in ribosomal proteins L4 and L22 of the large ribosomal subunit on the kinetics of erythromycin binding. Our data are consistent with a mechanism in which the macrolide erythromycin enters and exits the ribosome through the nascent peptide exit tunnel, and suggest that these mutations both impair passive transport through the tunnel and distort the erythromycin-binding site. The growth-inhibitory action of erythromycin was characterized for bacterial populations with wild-type and L22-mutated ribosomes in drug efflux pump deficient and proficient backgrounds. The L22 mutation conferred reduced erythromycin susceptibility in the drug efflux pump proficient, but not deficient, background. This ‘masking' of drug resistance by pump deficiency was reproduced by modelling with input data from our biochemical experiments. We discuss the general principles behind the phenomenon of drug resistance ‘masking', and highlight its potential importance for slowing down the evolution of drug resistance among pathogens. PMID:19197244

  9. Association of defects in lead chloride and lead bromide: Ionic conductivity and dielectric loss measurements

    NARCIS (Netherlands)

    Brom, W.E. van den; Schoonman, J.; Wit, J.H.W. de

    The ionic conductivity data of pure and doped lead bromide without associated defects are used in order to explain the anomalous conductivity behaviour of copper (I) bromide and lead oxide-doped lead-bromide crystals. In these crystals precipitated dopant and associated defects are present. The

  10. Efflux Pump-mediated Drug Resistance in Burkholderia

    Directory of Open Access Journals (Sweden)

    Nicole L Podnecky

    2015-04-01

    Full Text Available Several members of the genus Burkholderia are prominent pathogens. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. Virtually all Burkholderia species are also resistant to polymyxin, prohibiting use of drugs like colistin that are available for treatment of infections caused by most other drug resistant Gram-negative bacteria. Despite clinical significance and antibiotic resistance of Burkholderia species, characterization of efflux pumps lags behind other non-enteric Gram-negative pathogens such as Acinetobacter baumannii and Pseudomonas aeruginosa. Although efflux pumps have been described in several Burkholderia species, they have been best studied in B. cenocepacia and B. pseudomallei. As in other non-enteric Gram-negatives, efflux pumps of the resistance nodulation cell division (RND family are the clinically most significant efflux systems in these two species. Several efflux pumps were described in B. cenocepacia, which when expressed confer resistance to clinically significant antibiotics, including aminoglycosides, chloramphenicol, fluoroquinolones, and tetracyclines. Three RND pumps have been characterized in B. pseudomallei, two of which confer either intrinsic or acquired resistance to aminoglycosides, macrolides, chloramphenicol, fluoroquinolones, tetracyclines, trimethoprim, and in some instances trimethoprim+sulfamethoxazole. Several strains of the host-adapted B. mallei, a clone of B. pseudomallei, lack AmrAB-OprA and are therefore aminoglycoside and macrolide susceptible. B. thailandensis is closely related to B. pseudomallei, but non-pathogenic to humans. Its pump repertoire and ensuing drug resistance profile parallels that of B. pseudomallei. An efflux pump in B. vietnamiensis plays a significant role in acquired aminoglycoside resistance. Summarily, efflux pumps are significant players in Burkholderia drug resistance.

  11. Production of hydrogen bromide by bromine-methane reactions at elevated temperature.

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, Robert W.; Larson, Richard S.

    2003-05-01

    Hydrogen bromide is a potentially useful intermediate for hydrogen production by electrolysis because it has a low cell potential and is extremely soluble in water. Processes have been proposed to exploit these properties, but among the important issues to be resolved is the efficiency of HBr production from hydrocarbon precursors. This investigation evaluated a fundamental facet of such a technology by studying the reaction of methane and bromine at elevated temperature to determine the yield and kinetics of HBr formation. Laboratory experimentation and computational chemistry were combined to provide a description of this reaction for possible application to reactor design at a larger scale. Experimental studies with a tubular flow reactor were used to survey a range of reactant ratios and reactor residence times at temperatures between 500 C and 800 C. At temperatures near 800 C with excess methane, conversions of bromine to HBr exceeded 90% and reaction products included solid carbon (soot) in stoichiometric amounts. At lower temperatures, HBr conversion was significantly reduced, the products included much less soot, and the formation of bromocarbon compounds was indicated qualitatively. Calculations of chemical equilibrium behavior and reaction kinetics for the experimental conditions were performed using the Sandia CHEMKIN package. An elementary multistep mechanism for the gas-phase chemistry was used together with a surface mechanism that assumed facile deposition of radical species at the reactor walls. Simulations with the laminar-flow boundary-layer code of the CHEMKIN package gave reasonable agreement with experimental data.

  12. Reversal of the Drug Binding Pocket Defects of the AcrB Multidrug Efflux Pump Protein of Escherichia coli.

    Science.gov (United States)

    Soparkar, Ketaki; Kinana, Alfred D; Weeks, Jon W; Morrison, Keith D; Nikaido, Hiroshi; Misra, Rajeev

    2015-10-01

    The AcrB protein of Escherichia coli, together with TolC and AcrA, forms a contiguous envelope conduit for the capture and extrusion of diverse antibiotics and cellular metabolites. In this study, we sought to expand our knowledge of AcrB by conducting genetic and functional analyses. We began with an AcrB mutant bearing an F610A substitution in the drug binding pocket and obtained second-site substitutions that overcame the antibiotic hypersusceptibility phenotype conferred by the F610A mutation. Five of the seven unique single amino acid substitutions--Y49S, V127A, V127G, D153E, and G288C--mapped in the periplasmic porter domain of AcrB, with the D153E and G288C mutations mapping near and at the distal drug binding pocket, respectively. The other two substitutions--F453C and L486W--were mapped to transmembrane (TM) helices 5 and 6, respectively. The nitrocefin efflux kinetics data suggested that all periplasmic suppressors significantly restored nitrocefin binding affinity impaired by the F610A mutation. Surprisingly, despite increasing MICs of tested antibiotics and the efflux of N-phenyl-1-naphthylamine, the TM suppressors did not improve the nitrocefin efflux kinetics. These data suggest that the periplasmic substitutions act by influencing drug binding affinities for the distal binding pocket, whereas the TM substitutions may indirectly affect the conformational dynamics of the drug binding domain. The AcrB protein and its homologues confer multidrug resistance in many important human bacterial pathogens. A greater understanding of how these efflux pump proteins function will lead to the development of effective inhibitors against them. The research presented in this paper investigates drug binding pocket mutants of AcrB through the isolation and characterization of intragenic suppressor mutations that overcome the drug susceptibility phenotype of mutations affecting the drug binding pocket. The data reveal a remarkable structure-function plasticity of the

  13. Thermal stability of octadecyltrimethylammonium bromide modified montmorillonite organoclay.

    Science.gov (United States)

    Xi, Yunfei; Zhou, Qin; Frost, Ray L; He, Hongping

    2007-07-15

    Organoclays are significant for providing a mechanism for the adsorption of organic molecules from potable water. As such their thermal stability is important. A combination of thermogravimetric analysis and infrared emission spectroscopy was used to determine this stability. Infrared emission spectroscopy (IES) was used to investigate the changes in the structure and surface characteristics of water and surfactant molecules in montmorillonite, octadecyltrimethylammonium bromide and organoclays prepared with the surfactant octadecyltrimethylammonium bromide with different surfactant loadings. These spectra collected at different temperatures give support to the results obtained from the thermal analysis and also provide additional evidence for the dehydration which is difficult to obtain by normal thermoanalytical techniques. The spectra provide information on the conformation of the surfactant molecules in the clay layers and the thermal decomposition of the organoclays. Infrared emission spectroscopy proved to be a useful tool for the study of the thermal stability of the organoclays.

  14. Liquid chromatographic determination of bromide in human milk and plasma.

    Science.gov (United States)

    Goewie, C E; Hogendoorn, E A

    1985-11-08

    A liquid chromatographic method for the determination of bromide present in human body fluids at the level of 0.5-5.0 ppm is presented. The method involves liquid--liquid extraction of lipids and other lipophilic compounds, destruction of the aqueous phase and analysis of the residue on an aminopropyl bonded silica column with UV detection at 214 nm. The method was applied to the analysis of 278 samples of Dutch human milk. Comparison of the results obtained with those from a routinely used colorimetric procedure for plasma indicated excellent agreement. The ease of automation of the described procedure and its excellent reproducibility make it a good alternative to existing methods for bromide analysis in body fluids.

  15. [2,6-Bis(dimethylaminomethylphenyl]selenium bromide monohydrate

    Directory of Open Access Journals (Sweden)

    Richard A. Varga

    2010-04-01

    Full Text Available In the title hydrated molecular salt, C12H19N2Se+·Br−·H2O, the two independent bromide anions lie on a twofold rotation axis. Strong intramolecular N→Se interactions [2.185 (3 and 2.181 (3 Å] are established by both N atoms of the organic group in the cation, in trans positions to each other, with an N—Se—N angle of 161.6 (1°, resulting in a T-shaped (C,N,N′Se core. In the crystal, dimeric associations are formed by Br...Se [3.662 (2 Å] and Br...H interactions [2.56 (6 and 2.63 (7 Å] involving two bromide anions, two cations and two water molecules.

  16. Food Safe Alternatives to Methyl Bromide in Country Ham Production

    OpenAIRE

    Preisser III, Richard Herman

    2016-01-01

    Dry cured meat production is a costly and long term investment for producers. Ham mites (Tyrophagus putrescentiae) are a common pest of dry cured products and cause devastating effects, potentially nullifying producers' investments due to loss of salable product, as well as regulatory concerns. Methyl bromide, a chemical fumigant used to control mite populations, is damaging to stratospheric ozone and will no longer be available. Presently, no alternative control measure has been approved to ...

  17. Conservative tracer bromide inhibits pesticide mineralisation in soil.

    Science.gov (United States)

    Bech, Tina B; Rosenbom, Annette E; Sørensen, Sebastian R; Jacobsen, Carsten S

    2017-03-01

    Bromide is a conservative tracer that is often applied with non-conservative solutes such as pesticides to estimate their retardation in the soil. It has been applied in concentrations of up to 250 g Br L-1, levels at which the growth of single-celled organisms can be inhibited. Bromide applications may therefore affect the biodegradation of non-conservative solutes in soil. The present study investigated the effect of potassium bromide (KBr) on the mineralisation of three pesticides - glyphosate, MCPA and metribuzin - in four agricultural A-horizon soils. KBr was added to soil microcosms at concentrations of 0, 0.5, 2.5 and 5 g Br- L-1 in the soil solution. The study concluded that KBr had a negative effect on pesticide mineralisation. The inhibitory effect varied depending on the KBr concentration, the type of pesticide and the type of soil. Furthermore, 16 S amplicon sequencing revealed that the KBr treatment generally reduced the abundance of bacteroidetes and proteobacteria on both an RNA and DNA level. Therefore, in order to reduce the effect of KBr on the soil bacterial community and consequently also on xenobiotic degradation, it is recommended that KBr be applied in a concentration that does not exceed 0.5 g Br- L-1 in the soil water. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Two new bismuth thiourea bromides: crystal structure, growth, and characterization.

    Science.gov (United States)

    Li, Ming; Li, R K

    2014-02-14

    Crystals of two new bismuth thiourea bromides, bismuth trithiourea bromide (Bi[CS(NH2)2]3Br3, BTB) and bismuth protonated-hexathiourea bromide (Bi[CS(NH2)2H]6Br9, BHB), have been successfully grown from hydrobromic acid solution with different pH values by slow evaporation. Single crystal X-ray diffraction reveals that BTB is isostructural to its Cl-analog crystallizing in a monoclinic space group Cc with unit cell dimensions of a = 8.6238(7) Å, b = 12.2506(11) Å, c = 15.5040(13) Å, β = 90.7810(10)° and Z = 4. In contrast, BHB crystallizes in a trigonal space group R3[combining macron]c with unit cell dimensions of a = b = 12.748(17) Å, c = 40.45(11) Å, and Z = 6. The protonation of the thiourea in BHB is confirmed by the structure solution, IR and Raman spectroscopy. The UV diffuse reflection spectra clearly indicate that both of the two crystals have good optical transparency in the range below 2000 nm. Both compounds decompose above 190 °C, and BHB melts at around 140 °C while BTB possesses a phase transition at 145 °C as indicated by thermogravimetric (TG) and differential thermal analysis (DTA).

  19. Characterization of As efflux from the roots of As hyperaccumulator Pteris vittata L.

    Science.gov (United States)

    Huang, Yi; Hatayama, Masayoshi; Inoue, Chihiro

    2011-12-01

    In some plant species, various arsenic (As) species have been reported to efflux from the roots. However, the details of As efflux by the As hyperaccumulator Pteris vittata remain unknown. In this study, root As efflux was investigated for different phosphorus (P) supply conditions during or after a 24-h arsenate uptake experiment under hydroponic growth conditions. During an 8-h arsenate uptake experiment, P-supplied (P+) P. vittata exhibited much greater arsenite efflux relative to arsenate uptake when compared with P-deprived (P-) P. vittata, indicating that arsenite efflux was not proportional to arsenate uptake. In the As efflux experiment following 24 h of arsenate uptake, arsenate efflux was also observed with arsenite efflux in the external solution. All the results showed relatively low rates of arsenate efflux, ranging from 5.4 to 16.1% of the previously absorbed As, indicating that a low rate of arsenate efflux to the external solution is also a characteristic of P. vittata, as was reported with arsenite efflux. In conclusion, after 24 h of arsenate uptake, both P+ and P- P. vittata loaded/effluxed similar amounts of arsenite to the fronds and the external solution, indicating a similar process of xylem loading and efflux for arsenite, with the order of the arsenite concentrations being solution ≪ roots ≪ fronds.

  20. Organic carbon efflux from a deciduous forest catchment in Korea

    Directory of Open Access Journals (Sweden)

    S. J. Kim

    2010-04-01

    Full Text Available Soil infiltration and surface discharge of precipitation are critical processes that affect the efflux of Dissolved Organic Carbon (DOC and Particulate Organic Carbon (POC in forested catchments. Concentrations of DOC and POC can be very high in the soil surface in most forest ecosystems and their efflux may not be negligible particularly under the monsoon climate. In East Asia, however, there are little data available to evaluate the role of such processes in forest carbon budget. In this paper, we address two basic questions: (1 how does stream discharge respond to storm events in a forest catchment? and (2 how much DOC and POC are exported from the catchment particularly during the summer monsoon period? To answer these questions, we collected hydrological data (e.g., precipitation, soil moisture, runoff discharge, groundwater level and conducted hydrochemical analyses (including DOC, POC, and six tracers in a deciduous forest catchment in Gwangneung National Arboretum in west-central Korea. Based on the end-member mixing analysis of the six storm events during the summer monsoon in 2005, the surface discharge was estimated as 30 to 80% of the total runoff discharge. The stream discharge responded to precipitation within 12 h during these storm events. The annual efflux of DOC and POC from the catchment was estimated as 0.04 and 0.05 t C ha−1 yr−1, respectively. Approximately 70% of the annual organic carbon efflux occurred during the summer monsoon period. Overall, the annual efflux of organic carbon was estimated to be about 10% of the Net Ecosystem carbon Exchange (NEE obtained by eddy covariance measurement at the same site. Considering the current trends of increasing intensity and amount of summer rainfall and the large interannual variability in NEE, ignoring the organic carbon efflux from forest catchments would result in an inaccurate estimation of the carbon sink strength of forest ecosystems in the monsoon

  1. Solid miscibility of common-anion lithium and sodium halides. Experimental determination of the region of demixing in lithium bromide + sodium bromide

    NARCIS (Netherlands)

    Oonk, H.A.J.; Wijk, H.J. van; Doornhof, D.

    1984-01-01

    The region of demixing of solid lithium bromide + sodium bromide mixtures has been measured by X-ray diffraction. The critical temperature of mixing corresponding to a thermodynamic fit of the experimental data is 513 K. Estimates are given of the regions of demixing in solid lithium chloride +

  2. Solid miscibility of common-anion lithium and sodium halides. Experimental determination of the region of demixing in lithium bromide + sodium bromide

    OpenAIRE

    Oonk, H.A.J.; Wijk, H.J. van; Doornhof, D

    1984-01-01

    The region of demixing of solid lithium bromide + sodium bromide mixtures has been measured by X-ray diffraction. The critical temperature of mixing corresponding to a thermodynamic fit of the experimental data is 513 K. Estimates are given of the regions of demixing in solid lithium chloride + sodium chloride and solid lithium iodide + sodium iodide.

  3. On the distribution of bromide and bromide/chlorinity ratios in the waters of the Arabian sea off central Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, F.P.; SenGupta, R.

    Water samples from surface to 2000 m depth at two stations in the Arabian Sea collected during the 82nd cruise of R V Gaveshani in November, 1980 were analysed for bromide. The average bromide concentration was 0.068 g/kg plus or minus 0...

  4. Kinetic properties of cyanase.

    Science.gov (United States)

    Anderson, P M; Little, R M

    1986-04-08

    Cyanase is an inducible enzyme in Escherichia coli that catalyzes the hydrolysis of cyanate. Bicarbonate is required for activity, perhaps as a substrate, and the initial product of the reaction is carbamate, which spontaneously breaks down to ammonia and bicarbonate [Anderson, P. M. (1980) Biochemistry 19, 2882]. The purpose of this study was to characterize the kinetic properties of cyanase. Initial velocity studies showed that both cyanate and bicarbonate act as competitive substrate inhibitors. A number of monovalent anions act as inhibitors. Azide and acetate appear to act as competitive inhibitors with respect to cyanate and bicarbonate, respectively. Chloride, bromide, nitrate, nitrite, and formate also inhibit, apparently as the result of binding at either substrate site. Malonate and several other dicarboxylic dianions at very low concentrations display "slow-binding", reversible inhibition which can be prevented by saturating concentrations of either substrate. The results are consistent with a rapid equilibrium random mechanism in which bicarbonate acts as a substrate, bicarbonate and cyanate bind at adjacent anion-binding sites, and both substrates can bind at the other substrate anion binding site to give a dead-end complex.

  5. Soil carbon dioxide (CO 2 ) efflux of two shrubs in response to plant ...

    African Journals Online (AJOL)

    Although plant density should affect soil carbon dioxide (CO2) efflux and carbon cycling in semi-arid regions, the effects of plant density on soil CO2 efflux are not well known. This study was performed to investigate the responses of soil CO2 efflux of two dominant shrubs (Caragana korshinkii and Salix psammophila) to ...

  6. In Vitro Methods to Study the Interplay of Drug Metabolism and Efflux in the Intestine

    NARCIS (Netherlands)

    Siissalo, Sanna; Heikkinen, Aki T.

    This review provides an overview of the in vitro methods currently used in studies of intestinal drug metabolism and active efflux with a special emphasis on the efflux-metabolism interplay. These methods include e. g. expressed enzymes or efflux transporters, fractionated intestinal cells, cell

  7. CO2 efflux from subterranean nests of ant communities in a seasonal tropical forest, Thailand.

    Science.gov (United States)

    Hasin, Sasitorn; Ohashi, Mizue; Yamada, Akinori; Hashimoto, Yoshiaki; Tasen, Wattanachai; Kume, Tomonori; Yamane, Seiki

    2014-10-01

    Many ant species construct subterranean nests. The presence of their nests may explain soil respiration "hot spots", an important factor in the high CO2 efflux from tropical forests. However, no studies have directly measured CO2 efflux from ant nests. We established 61 experimental plots containing 13 subterranean ant species to evaluate the CO2 efflux from subterranean ant nests in a tropical seasonal forest, Thailand. We examined differences in nest CO2 efflux among ant species. We determined the effects of environmental factors on nest CO2 efflux and calculated an index of nest structure. The mean CO2 efflux from nests was significantly higher than those from the surrounding soil in the wet and dry seasons. The CO2 efflux was species-specific, showing significant differences among the 13 ant species. The soil moisture content significantly affected nest CO2 efflux, but there was no clear relationship between nest CO2 efflux and nest soil temperature. The diameter of the nest entrance hole affected CO2 efflux. However, there was no significant difference in CO2 efflux rates between single-hole and multiple-hole nests. Our results suggest that in a tropical forest ecosystem the increase in CO2 efflux from subterranean ant nests is caused by species-specific activity of ants, the nest soil environment, and nest structure.

  8. Phospholipid containing mixed micelles. Characterization of diheptanoyl phosphatidylcholine (DHPC) and sodium dodecyl sulfate and DHPC and dodecyl trimethylammonium bromide.

    Science.gov (United States)

    Ranganathan, Radha; Vautier-Giongo, Carolina; Bakshi, Mandeep Singh; Bales, Barney L; Hajdu, Joseph

    2005-05-01

    Mixed micelles of l,2-diheptanoyl-sn-grycero-3-phosphocholine (DHPC) with ionic detergents were prepared to develop well characterized substrates for the study of lipolytic enzymes. The aggregates that formed on mixing DHPC with the anionic surfactant sodium dodecyl sulfate (SDS) and with the positively charged dodecyl trimethylammonium bromide (DTAB) were investigated using time-resolved fluorescence quenching (TRFQ) to determine the aggregation numbers and bimolecular collision rates, and electron spin resonance (ESR) to measure the hydration index and microviscosity of the micelles at the micelle-water interface. Mixed micelles between the phospholipid and each of the detergents formed in all compositions, yielding interfaces with varying charge, hydration, and microviscosity. Both series of micelles were found to be globular up to 0.7 mole fraction of DHPC, while the aggregation numbers varied within the same concentration range of the components less than 15%. Addition of the zwitterionic phospholipid component increased the degree of counterion dissociation as measured by the quenching of the fluorescence of pyrene by the bromide ions bound to DHPC/DTAB micelles, showing that at 0.6 mole fraction of DHPC 80% of the bromide ions are dissociated from the micelles. The interface water concentration decreased significantly on addition of DHPC to each detergent. For combined phospholipid and detergent concentration of 50 mM the interface water concentration decreased, as measured by ESR of the spin-probes, from 38.5 M/L of interface volume in SDS alone to 9 M/L when the phospholipid was present at 0.7 mole fraction. Similar addition of DHPC to DTAB decreased the interfacial water concentration from 27 M/L to 11 M/L. Determination of the physicochemical parameters of the phospholipid containing mixed micelles here presented are likely to provide important insight into the design of assay systems for kinetic studies of phospholipid metabolizing enzymes.

  9. Recent advances toward a molecular mechanism of efflux pump inhibition

    Directory of Open Access Journals (Sweden)

    Timothy J Opperman

    2015-05-01

    Full Text Available Multi-drug resistance (MDR in Gram-negative pathogens, such as the Enterobacteriaceae and Pseudomonas aeruginosa, poses a significant threat to our ability to effectively treat infections caused by these organisms. A major component in the development of the MDR phenotype in Gram-negative bacteria is overexpression of RND-type efflux pumps, which actively pump antibacterial agents and biocides from the periplasm to the outside of the cell. Consequently, bacterial efflux pumps are an important target for developing novel antibacterial treatments. Potent efflux pump inhibitors (EPIs could be used as adjuvant therapies that would increase the potency of existing antibiotics and decrease the emergence of MDR bacteria. Several potent inhibitors of RND type efflux pump have been reported in the literature, and at least three of these EPI series were optimized in a pre-clinical development program. However, none of these compounds have been tested in the clinic. One of the major hurdles to the development of EPIs has been the lack of biochemical, computational, and structural methods that could be used to guide rational drug design. Here we review recent reports that have advanced our understanding of the mechanism of action of several potent EPIs against RND-type pumps.

  10. Effect of phosphorus limiting on phytase activity, proton efflux and ...

    African Journals Online (AJOL)

    This work intended to measure the nodulated-roots oxygen consumption, proton efflux and phytase activity in 2 lines of common bean (Phaseolus vulgaris) (115, 147) ... This may represent an adaptive mechanism for N2- fixing legumes to respond to P deficiency, by increasing the utilisation and the uptake of phosphorus for ...

  11. Efflux Pump.Mediated Resistance in Chemotherapy | Ughachukwu ...

    African Journals Online (AJOL)

    more important to the clinician and pharmacologist, as they constitute an important cause of antimicrobial drug resistance, which contributes to treatment failure, high medical bills, and increased mortality / morbidity. This review was aimed at highlighting the role of efflux pump mechanisms in microbial resistance to ...

  12. In-silico identification and phylogenetic analysis of auxin efflux ...

    African Journals Online (AJOL)

    ufuoma

    2014-01-08

    Jan 8, 2014 ... auxin throughout the plant is very important to maintain the auxin homeostasis. Auxin efflux carrier genes play ... from the Setaria italica genome, which are similar in number with that of monocotyledonous plant Oryza sativa. Twelve (12) SiPIN ..... Intelligence, Proceedings. pp. 634-639. Krecek P, Skupa P, ...

  13. Moderate alcohol consumption increases cholesterol efflux mediated by ABCA1

    NARCIS (Netherlands)

    Beulens, J.W.J.; Sierksma, A.; Tol, van A.; Fournier, C.

    2004-01-01

    Moderate alcohol consumption increases HDL cholesterol, which is involved in reverse cholesterol transport (RCT). The aim of this study was to investigate the effect of moderate alcohol consumption on cholesterol efflux, using J774 mouse macrophages and Fu5AH cells, and on other parameters in the

  14. In silico screening for antibiotic escort molecules to overcome efflux.

    Science.gov (United States)

    Rahman, Sheikh S; Simovic, Ivana; Gibbons, Simon; Zloh, Mire

    2011-11-01

    Resistance to antibiotics is a growing problem worldwide and occurs in part due to the overexpression of efflux pumps responsible for the removal of antibiotics from bacterial cells. The current study examines complex formation between efflux pump substrates and escort molecules as a criterion for an in silico screening method for molecules that are able to potentiate antibiotic activities. Initially, the SUPERDRUG database was queried to select molecules that were similar to known multidrug resistance (MDR) modulators. Molecular interaction fields generated by GRID and the docking module GLUE were used to calculate the interaction energies between the selected molecules and the antibiotic norfloxacin. Ten compounds forming the most stable complexes with favourable changes to the norfloxacin molecular properties were tested for their potentiation ability by efflux pump modulation assays. Encouragingly, two molecules were proven to act as efflux pump modulators, and hence provide evidence that complex formation between a substrate and a drug can be used for in silico screening for novel escort molecules.

  15. CO2 efflux from soils with seasonal water repellency

    Science.gov (United States)

    Urbanek, Emilia; Doerr, Stefan H.

    2017-10-01

    Soil carbon dioxide (CO2) emissions are strongly dependent on pore water distribution, which in turn can be modified by reduced wettability. Many soils around the world are affected by soil water repellency (SWR), which reduces infiltration and results in diverse moisture distribution. SWR is temporally variable and soils can change from wettable to water-repellent and vice versa throughout the year. Effects of SWR on soil carbon (C) dynamics, and specifically on CO2 efflux, have only been studied in a few laboratory experiments and hence remain poorly understood. Existing studies suggest soil respiration is reduced with increasing severity of SWR, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known.Here we report on the first field-based study that tests whether SWR indeed reduces soil CO2 efflux, based on in situ measurements carried out over three consecutive years at a grassland and pine forest sites under the humid temperate climate of the UK.Soil CO2 efflux was indeed very low on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. Low CO2 efflux was also observed when SWR was absent, in spring and late autumn when soil temperatures were low, but also in summer when SWR was reduced by frequent rainfall events. The highest CO2 efflux occurred not when soil was wettable, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. Patchiness of SWR is likely to have created zones with two different characteristics related to CO2 production and transport. Zones with wettable soil or low persistence of SWR with higher proportion of water-filled pores are expected to provide water with high nutrient concentration resulting in higher microbial activity and CO2 production. Soil zones with high SWR persistence, on the other hand, are dominated by air-filled pores with low microbial activity, but facilitating O2

  16. CO2 efflux from soils with seasonal water repellency

    Directory of Open Access Journals (Sweden)

    E. Urbanek

    2017-10-01

    Full Text Available Soil carbon dioxide (CO2 emissions are strongly dependent on pore water distribution, which in turn can be modified by reduced wettability. Many soils around the world are affected by soil water repellency (SWR, which reduces infiltration and results in diverse moisture distribution. SWR is temporally variable and soils can change from wettable to water-repellent and vice versa throughout the year. Effects of SWR on soil carbon (C dynamics, and specifically on CO2 efflux, have only been studied in a few laboratory experiments and hence remain poorly understood. Existing studies suggest soil respiration is reduced with increasing severity of SWR, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known.Here we report on the first field-based study that tests whether SWR indeed reduces soil CO2 efflux, based on in situ measurements carried out over three consecutive years at a grassland and pine forest sites under the humid temperate climate of the UK.Soil CO2 efflux was indeed very low on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. Low CO2 efflux was also observed when SWR was absent, in spring and late autumn when soil temperatures were low, but also in summer when SWR was reduced by frequent rainfall events. The highest CO2 efflux occurred not when soil was wettable, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. Patchiness of SWR is likely to have created zones with two different characteristics related to CO2 production and transport. Zones with wettable soil or low persistence of SWR with higher proportion of water-filled pores are expected to provide water with high nutrient concentration resulting in higher microbial activity and CO2 production. Soil zones with high SWR persistence, on the other hand, are dominated by air-filled pores with low microbial activity

  17. Transient anisocoria in a patient treated with nebulized ipratropium bromide

    Directory of Open Access Journals (Sweden)

    Renato Pejic

    2017-09-01

    Conclusions and importance: Presence of anisocoria may be a concerning neurological sign. If there are no other neurological or ophthalmological signs and symptoms and a recent ipratropium bromide inhalation treatment exists in the patient's history, we should consider iatrogenic side-effect of drugs as a possible reason of anisocoria and possibly spare the patient extensive and invasive diagnostic procedures that can also raise costs of treatment significantly. Observing neurological status and testing with 1% pilocarpine solution may be necessary to determine the etiology of this condition.

  18. Suicide by intravenous injection of rocuronium-bromide: Case report

    Directory of Open Access Journals (Sweden)

    Nikolić Slobodan

    2005-01-01

    Full Text Available Suicides by intravenous injection of an overdose of medicaments are uncommon. In this paper, we present the case of a suicide by rocuronium-bromide injection in combination with an oral overdose of metoprolol. Unfortunately, in Belgrade, there is no toxicological laboratory capable of detecting rocuronium. The interpretation of autopsy and toxicological data in this case was made difficult due to the extreme putrefaction of the body of the deceased. So, by forensic investigation, the case was solved indirectly, through circumstantial evidence: an empty ampoule of rocuronium found near the body, as well as a plastic syringe and cloth-bandage found in the left hand of the deceased.

  19. Kinetic Interface

    DEFF Research Database (Denmark)

    2009-01-01

    A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises.......A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises....

  20. Deciphering the role of RND efflux transporters in Burkholderia cenocepacia.

    Directory of Open Access Journals (Sweden)

    Silvia Bazzini

    Full Text Available Burkholderia cenocepacia J2315 is representative of a highly problematic group of cystic fibrosis (CF pathogens. Eradication of B. cenocepacia is very difficult with the antimicrobial therapy being ineffective due to its high resistance to clinically relevant antimicrobial agents and disinfectants. RND (Resistance-Nodulation-Cell Division efflux pumps are known to be among the mediators of multidrug resistance in gram-negative bacteria. Since the significance of the 16 RND efflux systems present in B. cenocepacia (named RND-1 to -16 has been only partially determined, the aim of this work was to analyze mutants of B. cenocepacia strain J2315 impaired in RND-4 and RND-9 efflux systems, and assess their role in the efflux of toxic compounds. The transcriptomes of mutants deleted individually in RND-4 and RND-9 (named D4 and D9, and a double-mutant in both efflux pumps (named D4-D9, were compared to that of the wild-type B. cenocepacia using microarray analysis. Microarray data were confirmed by qRT-PCR, phenotypic experiments, and by Phenotype MicroArray analysis. The data revealed that RND-4 made a significant contribution to the antibiotic resistance of B. cenocepacia, whereas RND-9 was only marginally involved in this process. Moreover, the double mutant D4-D9 showed a phenotype and an expression profile similar to D4. The microarray data showed that motility and chemotaxis-related genes appeared to be up-regulated in both D4 and D4-D9 strains. In contrast, these gene sets were down-regulated or expressed at levels similar to J2315 in the D9 mutant. Biofilm production was enhanced in all mutants. Overall, these results indicate that in B. cenocepacia RND pumps play a wider role than just in drug resistance, influencing additional phenotypic traits important for pathogenesis.

  1. Obtaining tabular silver bromide crystals using double-jet method in the presence of dimethyl sulfoxide

    Energy Technology Data Exchange (ETDEWEB)

    Dyonizy, A.; Nowak, P. [Institute of Physical and Theoretical Chemistry, Wroclaw University of Technology, Wybrzeze St., Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2010-11-15

    Water-gelatine suspensions containing tabular crystals of silver bromide were obtained using the modified double-jet method, in the presence of dimethyl sulfoxide and an excess of bromide ions, used to increase silver bromide solubility. The size and morphology of crystals obtained depend mostly on the constant concentration of complexing agents in the dispersive solution, during nucleation and crystal growth. The influence of excessive bromide ions concentration and volumetric concentration of dimethyl sulfoxide in the crystallising mixture on the formation of tabular - triangular or hexagonal thin plates - of high aspect ratio has been analysed. During experiment, optimal ranges of dimethyl sulfoxide and excessive bromide ions concentrations for obtaining interesting forms of flat silver bromide crystals were determined. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Morphology of silver bromide crystals produced at presence of N,N -dimethylformamide

    Energy Technology Data Exchange (ETDEWEB)

    Dyonizy, A.; Nowak, P. [Institute of Physical and Theoretical Chemistry, Wroclaw University of Technology (Poland)

    2010-08-15

    The study deals with examination of conditions that are necessary to obtain flat crystals of silver bromide that grow in a water and gelatine crystallization environment where N,N -dimethylformamide is used as the agent that is conducive to complexing of sparingly soluble silver bromide. The examination focused on the issue how changes in volumetric concentration of N,N -dimethylformamide as well as concentration of excessive ions of silver bromide in the dispersive solution affect morphology and size of newly created of silver bromide. The completed experiments enabled to determine boundary limits of both N,N -dimethylformamide and bromide ions concentration where suspensions of silver bromide crystals exhibit predominant content of triangular, transient and hexagonal flat forms with very high aspect ratio. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Transient neuromyopathy after bromide intoxication in a dog with idiopathic epilepsy

    OpenAIRE

    Steinmetz Sonja; Tipold Andrea; Bilzer Thomas; Schenk Henning

    2012-01-01

    Abstract A seven-year old Australian Shepherd, suffering from idiopathic epilepsy under treatment with phenobarbitone and potassium bromide, was presented with generalised lower motor neuron signs. Electrophysiology and muscle-nerve biopsies revealed a neuromyopathy. The serum bromide concentration was increased more than two-fold above the upper reference value. Clinical signs disappeared after applying diuretics and reducing the potassium bromide dose rate. This is the first case report des...

  4. Kinetics of extracellular ATP in mastoparan 7-activated human erythrocytes

    Science.gov (United States)

    Denis, María Florencia Leal; Incicco, J. Jeremías; Espelt, María Victoria; Verstraeten, Sandra V.; Pignataro, Omar P.; Lazarowski, Eduardo R.; Schwarzbaum, Pablo J.

    2014-01-01

    SUMMARY Background The peptide mastoparan 7 (MST7) stimulated ATP release in human erythrocytes. We explored intra- and extracellular processes governing the time-dependent accumulation of extracellular ATP (i.e., ATPe kinetics). Methods Human erythrocytes were treated with MST7 in the presence or absence of two blockers of pannexin 1. ATPe concentration was monitored by luciferin-luciferase based real-time luminometry. Results Exposure of human erythrocytes to MST7 led to an acute increase in [ATPe], followed by a slower increase phase. ATPe kinetics reflected a strong activation of ATP efflux and a low rate of ATPe hydrolysis by ectoATPase activity. Enhancement of [ATPe] by MST7 required adhesion of erythrocytes to poly-D-lysin-coated coverslips, and correlated with a 31% increase of cAMP and 10% cell swelling. However, when MST7 was dissolved in a hyperosmotic medium to block cell swelling, ATPe accumulation was inhibited by 49%. Erythrocytes pre-exposure to 10 μM of either carbenoxolone or probenecid, two blockers of pannexin 1, exhibited a partial reduction of ATP efflux. Erythrocytes from pannexin 1 knockout mice exhibited similar ATPe kinetics as those of wild type mice erythrocytes exposed to pannexin 1 blockers. Conclusions MST7 induced release of ATP required either cell adhesion or strong activation of cAMP synthesis. Part of this release required cell swelling. Kinetic analysis and a data driven model suggested that ATP efflux is mediated by two ATP conduits displaying different kinetics, with one conduit being fully blocked by pannexin 1 blockers. General Significance Kinetic analysis of extracellular ATP accumulation from human erythrocytes and potential effects on microcirculation. PMID:23742824

  5. Transient neuromyopathy after bromide intoxication in a dog with idiopathic epilepsy

    Directory of Open Access Journals (Sweden)

    Steinmetz Sonja

    2012-12-01

    Full Text Available Abstract A seven-year old Australian Shepherd, suffering from idiopathic epilepsy under treatment with phenobarbitone and potassium bromide, was presented with generalised lower motor neuron signs. Electrophysiology and muscle-nerve biopsies revealed a neuromyopathy. The serum bromide concentration was increased more than two-fold above the upper reference value. Clinical signs disappeared after applying diuretics and reducing the potassium bromide dose rate. This is the first case report describing electrophysiological and histopathological findings associated with bromide induced lower motor neuron dysfunction in a dog.

  6. [Adsorption of phenanthrene from aqueous solution on cetylpyridinium bromide (CPB) -modified zeolite].

    Science.gov (United States)

    Li, Jia; Lin, Jian-Wei; Zhan, Yan-Hui; Chen, Zu-Mei; Wang, Peng-Jun

    2014-02-01

    Surfactant-modified zeolites (SMZs) with different coverage types were prepared by loading of different amounts of cetylpyridinium bromide (CPB) onto natural zeolites and were used as adsorbents to remove phenanthrene from aqueous solution. The adsorption of phenanthrene from aqueous solution on monolayer and bilayer SMZs as a function of adsorbent dosage, initial phenanthrene concentration, contact time, and temperature was investigated using batch experiments. Results showed monolayer and bilayer SMZs were effective for the removal of phenanthrene from aqueous solution. The phenanthrene removal efficiency of SMZs increased with increasing adsorbent dosage, but the amount of phenanthrene adsorbed on SMZs decreased with increasing adsorbent dosage. The adsorption kinetics of phenanthrene on SMZs well followed a pseudo-second-order kinetic model. The equilibrium adsorption data of phenanthrene on SMZs at a low concentration of phenanthrene in solution could be described by the Linear equation and Freundlich equation. The main mechanism for phenanthrene adsorption onto monolayer SMZ is hydrophobic interaction, and the main mechanism for phenanthrene adsorption onto bilayer SMZ is organic partitioning. The calculated thermodynamic parameters such as Gibbs free energy change (deltaG(theta)), enthalpy changes (deltaH(theta)), and entropy change (deltaS(theta)) showed that the adsorption process of phenanthrene on SMZs is spontaneous and exothermic in nature. When the CPB loading amount of bilayer SMZ was twice as much as that of monolayer SMZ, the phenanthrene adsorption capacity for bilayer SMZ was slightly higher than that for monolayer SMZ. In a conclusion, both monolayer and bilayer SMZs are promising adsorbents for the removal of phenanthrene from water and wastewater, and monolayer SMZ is a more cost-effective adsorbent for phenanthrene removal than bilayer SMZ.

  7. IUPAC-NIST Solubility Data Series. 94. Rare Earth Metal Iodides and Bromides in Water and Aqueous Systems. Part 2. Bromides

    Science.gov (United States)

    Mioduski, Tomasz; Gumiński, Cezary; Zeng, Dewen; Voigt, Heidelore

    2013-03-01

    This work presents solubility data for rare earth metal bromides in water and in aqueous ternary systems. Compilations of all available experimental data are introduced for each rare earth metal bromide with a corresponding critical evaluation. Every such evaluation contains a collection of all solubility results in water, a selection of suggested solubility data and a brief discussion of the multicomponent systems. Because the ternary systems were almost never studied more than once, no critical evaluations of such data were possible. Only simple bromides (no complexes) are treated as the input substances in this work. The literature has been covered through the end of 2011.

  8. Field ionization kinetic and electron impact studies of gas phase transition states - The cyclic bromonium ion

    Science.gov (United States)

    Green, M. M.; Giguere, R. J.; Falick, A. M.; Aberth, W.; Burlingame, A. L.

    1978-01-01

    Cis- and trans-isomers of 4-t-butylcyclohexyl bromide were studied to determine the mechanism of cyclic bromonium ion formation. The field ionization kinetic and electron impact data indicate that the formation of the cyclic structure occurs simultaneously with loss of the neutral fragment. The data also show that little or no gas-phase cis-trans isomerization occurs.

  9. Kinetics and mechanism of the oxidation of some neutral and acidic ...

    Indian Academy of Sciences (India)

    Unknown

    Addition of bromide ion causes decrease in the oxidation rate but only to a limiting value. The reaction is susceptible to both polar and steric effects of the substituents. A suitable mechanism has been propo- sed. Keywords. Amino acid; tetraalkylammonium tribromide; kinetics; mechanism; oxidation. 1. Introduction.

  10. Uptake of bromide by two wetland plants (Typha latifolia L. and Phragmites australis (Cav.) Trin. ex Steud).

    Science.gov (United States)

    Xu, Shangping; Leri, Alessandra C; Myneni, Satish C B; Jaffe, Peter R

    2004-11-01

    The successful use of bromide (Br-) as a conservative tracer for hydrological tests in wetland systems requires minimal Br- loss due to plant uptake. The uptake of Br- by two wetland plants, cattail (Typha latifolia L.) and reed grass (Phragmites australis (Cav.) Trin. ex Steud), was investigated in greenhouse flow-through microcosms. Concentrations of Br- and other pertinent constituents in sediment pore water were measured at 2 cm depth increments in the sediment column. The vertical Br- concentration profiles in the sediments clearly revealed Br- uptake by T. latifolia and by P. australis. X-ray spectroscopy studies of bromine in plant samples revealed the accumulation of Br- in root and leaf tissues. Plant transpiration was found to significantly concentrate dissolved species in sediments and was accounted for in the calculations of Br uptake rates. Michaelis-Menten kinetics satisfactorily describe Br- uptake by T. latifolia. The uptake of Br- by P. australis, however, showed unique features that could not be described using Michaelis-Menten kinetics. The addition of chloride (Cl-) effectively inhibited Br- uptake, and the uptake of Cl- and Br- by T. latifolia was shown to follow dual-substrate Michaelis-Menten kinetics. Results of this study indicate that the use of Br- for tracer experiments in vegetated wetland systems should be evaluated with great caution.

  11. Hydrodynamic Controls on Carbon Dioxide Efflux from Inland Waters

    Science.gov (United States)

    Long, H. E.; Waldron, S.; Hoey, T.; Newton, J.; Quemin, S.

    2013-12-01

    Intensive research has been undertaken on carbon dioxide efflux from lakes, estuaries and oceans, but much less attention has been given to rivers and streams, especially lower order streams. River systems are often over-saturated with carbon dioxide and so tend to act as sources of carbon dioxide to the atmosphere. It has been thought that rivers act as pipes carrying this terrestrial carbon to the oceans. However, recent studies have shown that a significant amount of the carbon is reprocessed within the system in a series of transformations and losses. Fluvial evasion of carbon dioxide is now recognised to be a significant component of carbon cycles, however the factors controlling carbon dioxide efflux and its magnitude remain poorly understood and quantified. This research aims to quantify, and better understand the controls on, freshwater carbon dioxide evasion. Data are presented here from field measurements that commenced in Sept 2013 in two contrasting Scottish rivers: the River Kelvin which has a large (335 km.sq) part-urban catchment with predominantly non-peat soils and Drumtee Water, a small (9.6 km.sq) rural catchment of peat soils and agricultural land. Using a floating chamber with the headspace connected to an infrared gas analyser to measure changes in carbon dioxide concentration, efflux rates from 0.22 - 47.4 μmol CO2/m.sq/sec were measured, these close to the middle of the range of previously reported values. At one site on the River Kelvin in May 2013 an influx of -0.61 - -3.53 μmol CO2/m.sq/sec was recorded. Whereas previous research finds carbon dioxide efflux to increase with decreasing river size and a more organic-rich soil catchment, here the controls on carbon dioxide evasion are similar across the contrasting catchments. Carbon dioxide evasion shows seasonality, with maximum fluxes in the summer months being up to twice as high as the winter maxima. Linear regression demonstrates that evasion increases with increased flow velocity

  12. NOX2-dependent ROS is required for HDAC5 nuclear efflux and contributes to HDAC4 nuclear efflux during intense repetitive activity of fast skeletal muscle fibers

    Science.gov (United States)

    Liu, Yewei; Hernández-Ochoa, Erick O.; Randall, William R.

    2012-01-01

    Reactive oxygen species (ROS) have been linked to oxidation and nuclear efflux of class IIa histone deacetylase 4 (HDAC4) in cardiac muscle. Here we use HDAC-GFP fusion proteins expressed in isolated adult mouse flexor digitorum brevis muscle fibers to study ROS mediation of HDAC localization in skeletal muscle. H2O2 causes nuclear efflux of HDAC4-GFP or HDAC5-GFP, which is blocked by the ROS scavenger N-acetyl-l-cysteine (NAC). Repetitive stimulation with 100-ms trains at 50 Hz, 2/s (“50-Hz trains”) increased ROS production and caused HDAC4-GFP or HDAC5-GFP nuclear efflux. During 50-Hz trains, HDAC5-GFP nuclear efflux was completely blocked by NAC, but HDAC4-GFP nuclear efflux was only partially blocked by NAC and partially blocked by the calcium-dependent protein kinase (CaMK) inhibitor KN-62. Thus, during intense activity both ROS and CaMK play roles in nuclear efflux of HDAC4, but only ROS mediates HDAC5 nuclear efflux. The 10-Hz continuous stimulation did not increase the rate of ROS production and did not cause HDAC5-GFP nuclear efflux but promoted HDAC4-GFP nuclear efflux that was sensitive to KN-62 but not NAC and thus mediated by CaMK but not by ROS. Fibers from NOX2 knockout mice lacked ROS production and ROS-dependent nuclear efflux of HDAC5-GFP or HDAC4-GFP during 50-Hz trains but had unmodified Ca2+ transients. Our results demonstrate that ROS generated by NOX2 could play important roles in muscle remodeling due to intense muscle activity and that the nuclear effluxes of HDAC4 and HDAC5 are differentially regulated by Ca2+ and ROS during muscle activity. PMID:22648949

  13. Kinetics and

    Directory of Open Access Journals (Sweden)

    Mojtaba Ahmadi

    2016-11-01

    Full Text Available The aqueous degradation of Reactive Yellow 84 (RY84 by potassium peroxydisulfate (K2S2O8 has been studied in laboratory scale experiments. The effect of the initial concentrations of potassium peroxydisulfate and RY84, pH and temperature on RY84 degradation were also examined. Experimental data were analyzed using first and second-order kinetics. The degradation kinetics of RY84 of the potassium peroxydisulfate process followed the second-order reaction kinetics. These rate constants have an extreme values similar to of 9.493 mM−1min−1 at a peroxydisulfate dose of 4 mmol/L. Thermodynamic parameters such as activation (Ea and Gibbs free energy (ΔG° were also evaluated. The negative value of ΔGo and Ea shows the spontaneous reaction natural conditions and exothermic nature.

  14. Crystallization and preliminary X-ray diffraction analysis of the multidrug efflux transporter NorM from Neisseria gonorrhoeae

    Energy Technology Data Exchange (ETDEWEB)

    Su, C.C.; Long, F.; McDermott, G.; Shafer, W.M.; Yu, E.W. (Emory-MED); (UCSF); (Iowa State)

    2008-06-03

    The crystallization and preliminary X-ray data analysis of the NorM multidrug efflux pump produced by Neisseria gonorrhoeae are reported. NorM is a cytoplasmic membrane protein that consists of 459 amino-acid residues. It is a member of the recently classified multidrug and toxic compound extrusion (MATE) family of transporters and recognizes a number of cationic toxic compounds such as ethidium bromide, acriflavin, 2-N-methylellipticinium and ciprofloxacin. Recombinant NorM protein was expressed in Escherichia coli and purified by metal-affinity and gel-filtration chromatography. The protein was crystallized using hanging-drop vapor diffusion. X-ray diffraction data were collected from cryocooled crystals at a synchrotron light source. The best crystal diffracted anisotropically to 3.8 {angstrom} and diffraction data were complete to 6.5 {angstrom} resolution. The space group was determined to be C2, with unit-cell parameters a = 81.5, b = 164.4, c = 111.5 {angstrom}.

  15. Phytoremediation potentials of selected tropical plants for ethidium bromide.

    Science.gov (United States)

    Uera, Raynato B; Paz-Alberto, Annie Melinda; Sigua, Gilbert C

    2007-11-01

    Research and development has its own benefits and inconveniences. One of the inconveniences is the generation of enormous quantity of diverse toxic and hazardous wastes and its eventual contamination to soil and groundwater resources. Ethidium bromide (EtBr) is one of the commonly used substances in molecular biology experiments. It is highly mutagenic and moderately toxic substance used in DNA-staining during electrophoresis. Interest in phytoremediation as a method to solve chemical contamination has been growing rapidly in recent years. The technology has been utilized to clean up soil and groundwater from heavy metals and other toxic organic compounds in many countries like the United States, Russia, and most of European countries. Phytoremediation requires somewhat limited resources and very useful in treating wide variety of environmental contaminants. This study aimed to assess the potential of selected tropical plants as phytoremediators of EtBr. This study used tomato (Solanum lycopersicum), mustard (Brassica alba), vetivergrass (Vetiveria zizanioedes), cogongrass (Imperata cylindrica), carabaograss (Paspalum conjugatum), and talahib (Saccharum spontaneum) to remove EtBr from laboratory wastes. The six tropical plants were planted in individual plastic bags containing soil and 10% EtBr-stained agarose gel. The plants were allowed to establish and grow in soil for 30 days. Ethidium bromide content of the test plants and the soil were analyzed before and after soil treatment. Ethidium bromide contents of the plants and soils were analyzed using an UV VIS spectrophotometer. Results showed a highly significant (ptechnologies. Mustard had the highest potential as phytoremediator of EtBr in soil. However, the absorption capabilities of the other test plants may also be considered in terms of period of maturity and productivity. It is recommended that a more detailed and complete investigation of the phytoremediation properties of the different plants tested

  16. Molecular Dynamics Computer Simulations of Multidrug RND Efflux Pumps

    OpenAIRE

    Ruggerone, Paolo; Vargiu, Attilio V.; Collu, Francesca; Fischer, Nadine; Kandt, Christian

    2013-01-01

    Over-expression of multidrug efflux pumps of the Resistance Nodulation Division (RND) protein super family counts among the main causes for microbial resistance against pharmaceuticals. Understanding the molecular basis of this process is one of the major challenges of modern biomedical research, involving a broad range of experimental and computational techniques. Here we review the current state of RND transporter investigation employing molecular dynamics simulations providing conformation...

  17. Accumulation and efflux of polychlorinated biphenyls in Escherichia coli.

    Science.gov (United States)

    Geng, Shen; Fang, Jun; Turner, Kendrick B; Daunert, Sylvia; Wei, Yinan

    2012-06-01

    Polychlorinated biphenyls (PCBs) are environmental pollutants that have been associated with numerous adverse health effects in human and animals. Hydroxylated PCBs (HPCBs) are the product of the oxidative metabolism of PCBs. The presence of hydroxyl groups in HPCBs makes these compounds more hydrophilic than the parent PCBs. One of the best approaches to break down and remove these contaminants is bioremediation; an environmentally friendly process that uses microorganisms to degrade hazardous chemicals into non-toxic ones. In this study, we investigated the cellular accumulation and toxicity of selected PCBs and HPCBs in Gram-negative bacteria, using Escherichia coli as a model organism. We found that none of the five PCBs tested were toxic to E. coli, presumably due to their limited bioavailability. Nevertheless, different HPCBs tested showed different levels of toxicity. Furthermore, we demonstrated that the primary multidrug efflux system in E. coli, AcrAB-TolC, facilitated the efflux of HPCBs out of the cell. Since AcrAB-TolC is constitutively expressed in E. coli and is conserved in all sequenced Gram-negative bacterial genomes, our results suggest that the efflux activities of multidrug resistant pumps may affect the accumulation and degradation of PCBs in Gram-negative bacteria.

  18. ABCA17 mediates sterol efflux from mouse spermatozoa plasma membranes.

    Science.gov (United States)

    Morales, Carlos R; Ni, Xiaoyan; Smith, Charles E; Inagaki, Nobuya; Hermo, Louis

    2012-03-01

    Mammalian spermatozoa lose plasma membrane cholesterol during maturation in the epididymis and during capacitation in the female reproductive tract. While cholesterol acceptors such as high-density lipoproteins (HDL) and apolipoproteins A-I (apoA-I) and J (Apo J) have been found in male and female reproductive tracts, transporters that mediate cholesterol efflux from plasma membranes of spermatozoa to acceptors are not well defined. Candidates include members of the ATP-binding cassette (ABC) transporter superfamily including ABCA1, ABCA7, ABCA17, and ABCG1. In this study, we utilize immunocytochemistry on sections of adult mouse testis and epididymis and RT-PCR on isolated germ cells. The data reveal that ABCA17 is expressed by steps 12-16 elongated spermatids in the mouse in testis and by spermatozoa in the lumen of the epididymis where ABCA17 localizes to the sperm head and tail midpiece. It also localizes on these areas of mouse sperm isolated from the epididymis. Moreover, ABCA17 antibody interferes with cholesterol efflux from spermatozoa to lipid acceptors apoA-I. Taken together, these results suggest that ABCA17 plays an important role in the process of sterol efflux which renders spermatozoa capable of fertilizing an oocyte.

  19. Arsenate V induced glutathione efflux from human erythrocytes.

    Science.gov (United States)

    Yildiz, Deniz; Cakir, Yeliz

    2012-01-01

    The objective of the present study was to investigate if arsenate V exposure results in glutathione efflux from human erythrocytes. The changes in intracellular and extracellular nonprotein sulfhydryl and glutathione levels were determined in arsenate (V) exposed erythrocytes. Presence of any cellular membrane damage was assessed by lactate dehydrogenase activity measurement in the supernatant. When erythrocytes were exposed to 10 mM of arsenate (V) for 4 h, the intracellular NPSH level decreased to 0.28±0025 μmol/ml erythrocyte. In contrast, extracellular nonprotein thiol level was increased to 0.180±0.010 μmol/ml erythrocyte in 4 h. Extracellular glutathione levels reached to 0.028±0.001, 0.052±0.002, and 0.054±0.004 μmol/ml erythrocyte with 1, 5, and 10 mM of arsenate (V), respectively. Utilization of MK571 a multi drug resistance-associated protein 1 inhibitor decreased the rate of glutathione efflux from erythrocytes suggesting a role for this membrane transporter in the process. The results of the present study indicate that erythrocytes efflux glutathione when exposed to arsenate (V). Copyright © 2011 Elsevier GmbH. All rights reserved.

  20. A mass spectrometry-based assay for improved quantitative measurements of efflux pump inhibition.

    Directory of Open Access Journals (Sweden)

    Adam R Brown

    Full Text Available Bacterial efflux pumps are active transport proteins responsible for resistance to selected biocides and antibiotics. It has been shown that production of efflux pumps is up-regulated in a number of highly pathogenic bacteria, including methicillin resistant Staphylococcus aureus. Thus, the identification of new bacterial efflux pump inhibitors is a topic of great interest. Existing assays to evaluate efflux pump inhibitory activity rely on fluorescence by an efflux pump substrate. When employing these assays to evaluate efflux pump inhibitory activity of plant extracts and some purified compounds, we observed severe optical interference that gave rise to false negative results. To circumvent this problem, a new mass spectrometry-based method was developed for the quantitative measurement of bacterial efflux pump inhibition. The assay was employed to evaluate efflux pump inhibitory activity of a crude extract of the botanical Hydrastis Canadensis, and to compare the efflux pump inhibitory activity of several pure flavonoids. The flavonoid quercetin, which appeared to be completely inactive with a fluorescence-based method, showed an IC50 value of 75 μg/mL with the new method. The other flavonoids evaluated (apigenin, kaempferol, rhamnetin, luteolin, myricetin, were also active, with IC50 values ranging from 19 μg/mL to 75 μg/mL. The assay described herein could be useful in future screening efforts to identify efflux pump inhibitors, particularly in situations where optical interference precludes the application of methods that rely on fluorescence.

  1. A trial of emepronium bromide for the treatment of urinary incontinence in the elderly mentally ill.

    Science.gov (United States)

    Williams, A J; Prematalake, J K; Palmer, R L

    1981-01-01

    A double-blind controlled trial was conducted of emepronium bromide against placebo in elderly mentally ill patients in hospital with urinary incontinence. No significant difference was found between 200 mg emepronium bromide 3-times daily and placebo in treating day-time or nocturnal urinary incontinence for patients suffering from chronic organic brain syndrome or from chronic functional psychiatric illness.

  2. Destruction of methyl bromide sorbed to activated carbon by thiosulfate and electrolysis

    Science.gov (United States)

    Methyl bromide is widely used as a fumigant for post-harvest and quarantine uses at port facilities due to the low treatment times required, but it is vented to the atmosphere after its use. Due to the potential contributions of methyl bromide to stratospheric ozone depletion, technologies for the c...

  3. A study of bromide in the Mandovi-Zuari river system of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, F.P.; Dalal, V.N.K.

    concentrations were computed. The variation of bromide with chlorinity was linear indicating the purely conservative character of bromide and its seawater origin. Seawater ranged between 1 and 3% in monsoon, 76 and 91% in post-monsoon and 92 and 97% in pre...

  4. Infrared spectroscopy of organoclays synthesized with the surfactant octadecyltrimethylammonium bromide

    Science.gov (United States)

    Xi, Yunfei; Ding, Zhe; He, Hongping; Frost, Ray L.

    2005-01-01

    Infrared (IR) spectroscopy using a smart endurance single bounce diamond attenuated total reflection (ATR) cell has been used to study the changes in the spectra of the surfactant octadecyltrimethylammonium (ODTMA) bromide upon intercalation into a sodium montmorillonite. The wavenumbers of bands attributed to CH-stretching and CH-bending vibrations, in general, decrease as the concentration of the surfactant measured in terms of the cation exchange capacity (CEC) up to 1.0 CEC. After this point, the bands increase approaching a value the same as that of the surfactant. Significant changes occur in the HCH deformation modes of the methyl groups of the surfactant. These changes are attributed to the methyl groups locking into the siloxane (SiO) surface of the montmorillonite. Such a concept is supported by changes in the SiO-stretching bands of the montmorillonite siloxane surface.

  5. Mechanism of photolysis of Fe(III) bromide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Khmelinskii, I.V.; Plyusnin, V.F.; Grivin, V.P.

    1988-11-01

    Laser flash photolysis has been used to investigate the primary photoprocesses for bromide complexes of Fe(III) in a mixture of methanol and diethyl ether. The formation of the ion-radical Br/sub 2//sup -/ in the coordination sphere, followed by release into the bulk of the solvent, has been observed for the complex FeBr/sub 3/. In the case of FeBr/sub 2//sup +/ the Br atom is released into the solvent which in the reaction with the free Br/sup -/ ion also forms Br/sub 2//sup -/ . In the case of both complexes these channels compete with the transfer of an electron from the solvent molecules. The later reaction is suppressed for FeBr/sub 4//sup -/, leading mainly to the formation of the ion-radical Br/sub 2//sup -/.

  6. Timing resolution measurements of a 3 in. lanthanum bromide detector

    Energy Technology Data Exchange (ETDEWEB)

    Galli, L., E-mail: luca.galli@pi.infn.it [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); De Gerone, M. [INFN Sezione di Genova, Largo Dodecaneso 33, 16146 Genova (Italy); Dipartimento di Fisica dell' Università degli Studi di Genova, Largo Dodecaneso 33, 16146 Genova (Italy); Dussoni, S. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Nicolò, D. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Dipartimento di Fisica dell' Università degli Studi di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Papa, A. [Paul Scherrer Institute PSI, CH-5232 Villigen (Switzerland); Tenchini, F. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Dipartimento di Fisica dell' Università degli Studi di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Signorelli, G. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy)

    2013-08-01

    Cerium-doped lanthanum bromide (LaBr{sub 3}:Ce) is a scintillator that presents very good energy and timing resolutions and it is a perfect candidate for photon detector in future experiments to search for lepton flavor violation as in μ→eγ or μ→e conversion. While energy resolution was thoroughly investigated, timing resolution at several MeV presents some experimental challenge. We measured the timing resolution of a 3 in.×3 in. cylindrical LaBr{sub 3}(Ce) crystal versus few reference detectors by means of a nuclear reaction from a Cockcroft–Walton accelerator that produces coincident γ-rays in the 4.4–11.6 MeV range. Preliminary results allow us to extrapolate the properties of a segmented γ-ray detector in the 50–100 MeV range.

  7. Interplay between Mutations and Efflux in Drug Resistant Clinical Isolates of Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Miguel Viveiros

    2017-04-01

    Full Text Available Numerous studies show efflux as a universal bacterial mechanism contributing to antibiotic resistance and also that the activity of the antibiotics subject to efflux can be enhanced by the combined use of efflux inhibitors. Nevertheless, the contribution of efflux to the overall drug resistance levels of clinical isolates of Mycobacterium tuberculosis is poorly understood and still is ignored by many. Here, we evaluated the contribution of drug efflux plus target-gene mutations to the drug resistance levels in clinical isolates of M. tuberculosis. A panel of 17 M. tuberculosis clinical strains were characterized for drug resistance associated mutations and antibiotic profiles in the presence and absence of efflux inhibitors. The correlation between the effect of the efflux inhibitors and the resistance levels was assessed by quantitative drug susceptibility testing. The bacterial growth/survival vs. growth inhibition was analyzed through the comparison between the time of growth in the presence and absence of an inhibitor. For the same mutation conferring antibiotic resistance, different MICs were observed and the different resistance levels found could be reduced by efflux inhibitors. Although susceptibility was not restored, the results demonstrate the existence of a broad-spectrum synergistic interaction between antibiotics and efflux inhibitors. The existence of efflux activity was confirmed by real-time fluorometry. Moreover, the efflux pump genes mmr, mmpL7, Rv1258c, p55, and efpA were shown to be overexpressed in the presence of antibiotics, demonstrating the contribution of these efflux pumps to the overall resistance phenotype of the M. tuberculosis clinical isolates studied, independently of the genotype of the strains. These results showed that the drug resistance levels of multi- and extensively-drug resistant M. tuberculosis clinical strains are a combination between drug efflux and the presence of target-gene mutations, a reality

  8. In-silico interaction studies suggest RND efflux pump mediates polymyxin resistance in Acinetobacter baumannii.

    Science.gov (United States)

    Verma, Privita; Maurya, Pramila; Tiwari, Monalisa; Tiwari, Vishvanath

    2017-12-29

    Bacterial efflux pumps have emerged as antibiotic resistance determinants and confers multi-drug resistance to a broad range of antimicrobials as well as non-antibiotic substances. A study about translocation of antibiotic molecules through the efflux transporter, will contribute in determining substrate specificity. In the present study, we have explored RND family efflux pump extensively found in Acinetobacter baumannii i.e. AdeABC. Besides, another well studied RND efflux pump, AcrAB-TolC together with a non-RND efflux pump, NorM was investigated for comparative analysis. We employed a series of computational techniques ranging from molecular docking to binding free energy estimation and molecular dynamics simulations to determine the binding affinity for different classes of drugs, namely aminoglycosides, polymyxins, β-lactams, tetracyclines, glycylcyclines, quinolones and metronidazole with AdeB, AcrB, and NorM efflux proteins. Our results revealed that class polymyxins has the highest binding affinity with the RND efflux pumps i.e. AcrAB-TolC and AdeABC as well as non-RND efflux pump, NorM. The experimental validation study demonstrated bigger zone of inhibition in presence of efflux pump inhibitor than polymyxin alone thus unveiling its specificity toward efflux pump. The reported experimental data comprising of minimum inhibitory concentration of antibiotics toward these efflux pumps also support our finding based on in silico approach. To recapitulate the outcome, polymyxins shows maximum specificity toward RND as well as non-RND efflux pump and may unlatch the way to rationally develop new potential antibacterial agents as well as efflux pump inhibitors in order to combat resistance.

  9. Use of Competition Kinetics with Fast Reactions of Grignard Reagents

    DEFF Research Database (Denmark)

    Holm, Torkil

    2000-01-01

    Competition kinetics are useful for estimation of the reactivities of Grignard reagents if the reaction rates do not differ widely and if exact rates are not needed. If the rate of mixing is slower than the rate of reaction the ratios between the rates of fast and slow reagents are found to be too...... small.This is concluded from experiments in which results obtained by competition kinetics are compared with results obtained directly by flow stream procedures. A clearer picture of the reactivity ratios is obtained when the highly reactive reagent is highly diluted with its competitor. A fast reagent...... found for the four substrates do not differ significantly and it seems possible that there is a ceiling over the rate of reaction of this reagent, for example caused by diffusion control. This may explain that competition kinetics using allylmagnesium bromide have failed to show kinetic isotope effects...

  10. Vertical variations in wood CO2 efflux for live emergent trees in a Bornean tropical rainforest.

    Science.gov (United States)

    Katayama, Ayumi; Kume, Tomonori; Komatsu, Hikaru; Ohashi, Mizue; Matsumoto, Kazuho; Ichihashi, Ryuji; Kumagai, Tomo'omi; Otsuki, Kyoichi

    2014-05-01

    Difficult access to 40-m-tall emergent trees in tropical rainforests has resulted in a lack of data related to vertical variations in wood CO2 efflux, even though significant variations in wood CO2 efflux are an important source of errors when estimating whole-tree total wood CO2 efflux. This study aimed to clarify vertical variations in wood CO2 efflux for emergent trees and to document the impact of the variations on the whole-tree estimates of stem and branch CO2 efflux. First, we measured wood CO2 efflux and factors related to tree morphology and environment for seven live emergent trees of two dipterocarp species at four to seven heights of up to ∼ 40 m for each tree using ladders and a crane. No systematic tendencies in vertical variations were observed for all the trees. Wood CO2 efflux was not affected by stem and air temperature, stem diameter, stem height or stem growth. The ratios of wood CO2 efflux at the treetop to that at breast height were larger in emergent trees with relatively smaller diameters at breast height. Second, we compared whole-tree stem CO2 efflux estimates using vertical measurements with those based on solely breast height measurements. We found similar whole-tree stem CO2 efflux estimates regardless of the patterns of vertical variations in CO2 efflux because the surface area in the canopy, where wood CO2 efflux often differed from that at breast height, was very small compared with that at low stem heights, resulting in little effect of the vertical variations on the estimate. Additionally, whole-tree branch CO2 efflux estimates using measured wood CO2 efflux in the canopy were considerably different from those measured using only breast height measurements. Uncertainties in wood CO2 efflux in the canopy did not cause any bias in stem CO2 efflux scaling, but affected branch CO2 efflux. © The Author 2014. Published by Oxford University Press. All rights reserved.

  11. Kinetic Biochemistry

    OpenAIRE

    Jäntschi, Lorentz

    2003-01-01

    Mathematics and computer programming have a major contribution to chemistry. Two directions can be identified: one that searches and tries (rich) to explain the structural binding and shape of the chemical compounds [1] with major applications in QSPR/QSAR studies [2], and applied sciences such as engineering of materials or agriculture [3]; the second direction is to models the kinetic processes that are involved in chemical reactions [4]. Many such models are available here. The present pap...

  12. Kinetic Biochemistry

    Directory of Open Access Journals (Sweden)

    Lorentz JÄNTSCHI

    2003-03-01

    Full Text Available Mathematics and computer programming have a major contribution to chemistry. Two directions can be identified: one that searches and tries (rich to explain the structural binding and shape of the chemical compounds [1] with major applications in QSPR/QSAR studies [2], and applied sciences such as engineering of materials or agriculture [3]; the second direction is to models the kinetic processes that are involved in chemical reactions [4]. Many such models are available here. The present paper describes three variants of well the known kinetic models and presents the mathematical equations associated with them. The differential equations are numerically solved and fitted with MathCad program. [1] Diudea M., Gutman I., Jäntschi L., Molecular Topology, Nova Science, Huntington, New York, 332 p., 2001, 2002. [2] Diudea M. V., Ed., QSPR / QSAR Studies by Molecular Descriptors, Nova Science, Huntington, New York, 438 p., 2001. [3] Jäntschi L., Microbiology and Toxicology. Phytochemistry Studies (in Romanian, Amici, Cluj-Napoca, 184 p., 2003. [4] Jäntschi L., Unguresan M., Physical Chemistry. Molecular Kinetic and Dynamic (in Romanian, Mediamira, Cluj-Napoca, 159 p., 2001.

  13. Physisorption kinetics

    CERN Document Server

    Kreuzer, Hans Jürgen

    1986-01-01

    This monograph deals with the kinetics of adsorption and desorption of molecules physisorbed on solid surfaces. Although frequent and detailed reference is made to experiment, it is mainly concerned with the theory of the subject. In this, we have attempted to present a unified picture based on the master equation approach. Physisorption kinetics is by no means a closed and mature subject; rather, in writing this monograph we intended to survey a field very much in flux, to assess its achievements so far, and to give a reasonable basis from which further developments can take off. For this reason we have included many papers in the bibliography that are not referred to in the text but are of relevance to physisorption. To keep this monograph to a reasonable size, and also to allow for some unity in the presentation of the material, we had to omit a number of topics related to physisorption kinetics. We have not covered to any extent the equilibrium properties of physisorbed layers such as structures, phase tr...

  14. Wood CO2 efflux and foliar respiration for Eucalyptus in Hawaii and Brazil

    Science.gov (United States)

    Michael G. Ryan; Molly A. Cavaleri; Auro C. Almeida; Ricardo Penchel; Randy S. Senock; Jose Luiz Stape

    2009-01-01

    We measured CO2 efflux from wood for Eucalyptus in Hawaii for 7 years and compared these measurements with those on three- and four-and-a-halfyear- old Eucalyptus in Brazil. In Hawaii, CO2 efflux from wood per unit biomass declined ~10x from age two to age five, twice as much as the decline in tree growth. The CO2 efflux from wood in Brazil was 8-10· lower than that...

  15. A sensitive assay for ABCA1-mediated cholesterol efflux using BODIPY-cholesterol

    Science.gov (United States)

    Sankaranarayanan, Sandhya; Kellner-Weibel, Ginny; de la Llera-Moya, Margarita; Phillips, Michael C.; Asztalos, Bela F.; Bittman, Robert; Rothblat, George H.

    2011-01-01

    Studies have shown a negative association between cellular cholesterol efflux and coronary artery disease (CAD). Standard protocol for quantitating cholesterol efflux involves labeling cells with [3H]cholesterol and measuring release of the labeled sterol. Using [3H]cholesterol is not ideal for the development of a high-throughput assay to screen large numbers of serum as would be required in studying the link between efflux and CAD. We compared efflux using a fluorescent sterol (boron dipyrromethene difluoride linked to sterol carbon-24, BODIPY-cholesterol) with that of [3H]cholesterol in J774 macrophages. Fractional efflux of BODIPY-cholesterol was significantly higher than that of [3H]cholesterol when apo A-I, HDL3, or 2% apoB-depleted human serum were used as acceptors. BODIPY-cholesterol efflux correlated significantly with [3H]cholesterol efflux (p cholesterol efflux correlated significantly with preβ-1 (r2 = 0.6) but not with total HDL-cholesterol. Reproducibility of the BODIPY-cholesterol efflux assay was excellent between weeks (r2 = 0.98, inter-assay CV = 3.31%). These studies demonstrate that BODIPY-cholesterol provides an efficient measurement of efflux compared with [3H]cholesterol and is a sensitive probe for ABCA1-mediated efflux. The increased sensitivity of BODIPY-cholesterol assay coupled with the simplicity of measuring fluorescence results in a sensitive, high-throughput assay that can screen large numbers of sera, and thus establish the relationship between cholesterol efflux and atherosclerosis. PMID:21957199

  16. The role of the Serratia marcescens SdeAB multidrug efflux pump and TolC homologue in fluoroquinolone resistance studied via gene-knockout mutagenesis.

    Science.gov (United States)

    Begic, Sanela; Worobec, Elizabeth A

    2008-02-01

    Serratia marcescens is a prominent opportunistic nosocomial pathogen resistant to several classes of antibiotics. The major mechanism for fluoroquinolone resistance in various Gram-negative pathogens is active efflux. Our group previously identified SdeAB, a resistance-nodulation-cell division (RND) efflux pump complex, and a TolC-like outer-membrane protein (HasF), which together mediate energy-dependent fluoroquinolone efflux. In addition, a regulatory protein-encoding gene in the upstream region of sdeAB was identified (sdeR) and found to be 40 % homologous to MarA, an Escherichia coli transcriptional regulator. To provide conclusive evidence as to the role of these components in S. marcescens, sdeB, hasF and sdeR deletion mutants were constructed. Suicide vectors were created and introduced via triparental mating into S. marcescens UOC-67 (wild-type) and, for sdeB and hasF, T-861 (clinical isolate). We have analysed these genetically altered strains using minimal inhibitory concentration (MIC) assays for a wide range of compounds (fluoroquinolones, SDS, novobiocin, ethidium bromide and chloramphenicol). Intracellular accumulation of a variety of fluoroquinolones was measured fluorospectroscopically. The sdeB, hasF and sdeR knockout strains were consistently more susceptible to antibiotics than the parent strains, with the sdeB/hasF double knockout strain showing the highest susceptibility. A marked increase in fluoroquinolone (ciprofloxacin) accumulation was observed for strains deficient in either the sdeB or hasF genes when compared to the parental strains, with the highest ciprofloxacin accumulation observed for the sdeB/hasF double knockout. Antibiotic accumulation assays for the sdeB knockout mutant strains performed in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), a proton-motive-force inhibitor, demonstrated that SdeAB-mediated efflux is proton-motive-force dependent. Due to the comparable susceptibility of the sdeB and the has

  17. 40 CFR 180.123a - Inorganic bromide residues in peanut hay and peanut hulls; statement of policy.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Inorganic bromide residues in peanut... RESIDUES IN FOOD Specific Tolerances § 180.123a Inorganic bromide residues in peanut hay and peanut hulls... to cattle of peanut hay and peanut hulls containing residues of inorganic bromides will contribute...

  18. Role of efflux pumps and intracellular thiols in natural antimony resistant isolates of Leishmania donovani

    National Research Council Canada - National Science Library

    Rai, Smita; Bhaskar; Goel, Sudhir K; Nath Dwivedi, Upendra; Sundar, Shyam; Goyal, Neena

    2013-01-01

    .... Accordingly, the study of determinants of antimony resistance is urgently warranted. Efflux transporters have been reported in Leishmania but their role in clinical resistance is still unknown...

  19. The Heterodimeric ABC Transporter EfrCD Mediates Multidrug Efflux in Enterococcus faecalis

    National Research Council Canada - National Science Library

    Hürlimann, Lea M; Corradi, Valentina; Hohl, Michael; Bloemberg, Guido V; Tieleman, D Peter; Seeger, Markus A

    2016-01-01

    Nosocomial infections with Enterococcus faecalis are an emerging health problem. However, drug efflux pumps contributing to intrinsic drug resistance are poorly studied in this Gram-positive pathogen...

  20. The Cus efflux system removes toxic ions via a methionine shuttle.

    Science.gov (United States)

    Su, Chih-Chia; Long, Feng; Yu, Edward W

    2011-01-01

    Gram-negative bacteria, such as Escherichia coli, frequently utilize tripartite efflux complexes in the resistance-nodulation-cell division (RND) family to expel diverse toxic compounds from the cell. These efflux systems span the entire cell envelope to mediate the phenomenon of bacterial multidrug resistance. The three parts of the efflux complexes are: (1) a membrane fusion protein (MFP) connecting (2) a substrate-binding inner membrane transporter to (3) an outer membrane-anchored channel in the periplasmic space. One such efflux system CusCBA is responsible for extruding biocidal Cu(I) and Ag(I) ions. We recently determined the crystal structures of both the inner membrane transporter CusA and MFP CusB of the CusCBA tripartite efflux system from E. coli. These are the first structures of the heavy-metal efflux (HME) subfamily of the RND efflux pumps. Here, we summarize the structural information of these two efflux proteins and present the accumulated evidence that this efflux system utilizes methionine residues to bind and export Cu(I)/Ag(I). Genetic and structural analyses suggest that the CusA pump is capable of picking up the metal ions from both the periplasm and cytoplasm. We propose a stepwise shuttle mechanism for this pump to extrude metal ions from the cell.

  1. Niacin Therapy Increases High-Density Lipoprotein Particles and Total Cholesterol Efflux Capacity But Not ABCA1-Specific Cholesterol Efflux in Statin-Treated Subjects.

    Science.gov (United States)

    Ronsein, Graziella E; Hutchins, Patrick M; Isquith, Daniel; Vaisar, Tomas; Zhao, Xue-Qiao; Heinecke, Jay W

    2016-02-01

    We investigated relationships between statin and niacin/statin combination therapy and the concentration of high-density lipoprotein particles (HDL-P) and cholesterol efflux capacity, 2 HDL metrics that might better assess cardiovascular disease risk than HDL-cholesterol (HDL-C) levels. In the Carotid Plaque Composition Study, 126 subjects with a history of cardiovascular disease were randomized to atorvastatin or combination therapy (atorvastatin/niacin). At baseline and after 1 year of treatment, the concentration of HDL and its 3 subclasses (small, medium, and large) were quantified by calibrated ion mobility analysis (HDL-PIMA). We also measured total cholesterol efflux from macrophages and ATP-binding cassette transporter A1 (ABCA1)-specific cholesterol efflux capacity. Atorvastatin decreased low-density lipoprotein cholesterol by 39% and raised HDL-C by 11% (P=0.0001) but did not increase HDL-PIMA or macrophage cholesterol efflux. Combination therapy raised HDL-C by 39% (Pniacin therapy. Statin therapy increased HDL-C levels but failed to increase HDL-PIMA. It also reduced ABCA1-specific cholesterol efflux capacity. Adding niacin to statin therapy increased HDL-C and macrophage efflux, but had much less effect on HDL-PIMA. It also failed to improve ABCA1-specific efflux, a key cholesterol exporter in macrophages. Our observations raise the possibility that niacin might not target the relevant atheroprotective population of HDL. © 2015 American Heart Association, Inc.

  2. Clinical signs, risk factors, and outcomes associated with bromide toxicosis (bromism) in dogs with idiopathic epilepsy.

    Science.gov (United States)

    Rossmeisl, John H; Inzana, Karen D

    2009-06-01

    To evaluate clinical signs, risk factors, and outcomes associated with bromide toxicosis (bromism) in dogs with idiopathic epilepsy treated with potassium or sodium bromide. Retrospective case-control study. 83 clinically ill epileptic dogs with (cases; n = 31) and without (controls; 52) bromism. Medical records were reviewed for information regarding signalment, epilepsy history, treatment, diet, clinicopathologic test results, concurrent diseases, clinical signs, and outcome. Case and control dogs were matched by the veterinary hospitals from which they were referred and by month of admission. A presumptive diagnosis of bromism was made in case dogs when treatment for primary clinical signs was limited to induction of diuresis or reduction in the dose of bromide administered, and this diagnosis was supported by serum bromide concentrations. Potential risk factors for bromism were identified via univariate and subsequent multivariate logistic regression analyses. Common clinical signs of bromism included alterations in consciousness, ataxia, and upper and lower motor neuron tetraparesis and paraparesis. The multivariate analysis identified bromide dose at admission to the hospital as the only factor significantly associated with bromism. In all dogs with bromism, treatment via dose reduction or facilitated renal excretion of bromide resulted in rapid clinical improvement, although breakthrough seizures happened during treatment in 8 of 31 (26%) dogs. Bromism is a clinically heterogeneous, dose-dependent neurotoxicosis that is largely reversible with treatment. Regular serial monitoring of serum bromide concentrations is recommended to optimize anticonvulsant treatment in dogs with idiopathic epilepsy.

  3. Peptides having reduced toxicity that stimulate cholesterol efflux

    Energy Technology Data Exchange (ETDEWEB)

    Bielicki, John K.; Johansson, Jan; Danho, Waleed

    2016-08-16

    The present invention provides a family of non-naturally occurring polypeptides having cholesterol efflux activity that parallels that of full-length apolipoproteins (e.g., Apo AI and Apo E), and having high selectivity for ABCA1 that parallels that of full-length apolipoproteins. Further, the peptides of the invention have little or no toxicity when administered at therapeutic and higher doses. The invention also provides compositions comprising such polypeptides, methods of identifying, screening and synthesizing such polypeptides, and methods of treating, preventing or diagnosing diseases and disorders associated with dyslipidemia, hypercholesterolemia and inflammation.

  4. Gold micro- and nano-particles for surface enhanced vibrational spectroscopy of pyridostigmine bromide

    DEFF Research Database (Denmark)

    Dolgov, Leonid; Fesenko, Olena; Kavelin, Vladyslav

    2017-01-01

    Triangular gold microprisms and spherical silica nanoparticles with attached gold nano-islands were examined as an active nanostructures for the surface enhanced Raman and infrared spectroscopy. These particles were probed for the detection of pyridostigmine bromide as a safe analog of military...... compound sarin. Raman and infrared spectral bands of the pyridostigmine bromide were measured. Detailed correlation of obtained spectral bands with specific vibrations in pyridostigmine bromide was done. Silica nanoparticles with attached gold nano-islands showed more essential enhancement of the Raman...

  5. Advanced crystal growth techniques for thallium bromide semiconductor radiation detectors

    Science.gov (United States)

    Datta, Amlan; Becla, Piotr; Guguschev, Christo; Motakef, Shariar

    2018-02-01

    Thallium Bromide (TlBr) is a promising room-temperature radiation detector candidate with excellent charge transport properties. Currently, Travelling Molten Zone (TMZ) technique is widely used for growth of semiconductor-grade TlBr crystals. However, there are several challenges associated with this type of crystal growth process including lower yield, high thermal stress, and low crystal uniformity. To overcome these shortcomings of the current technique, several different crystal growth techniques have been implemented in this study. These include: Vertical Bridgman (VB), Physical Vapor Transport (PVT), Edge-defined Film-fed Growth (EFG), and Czochralski Growth (Cz). Techniques based on melt pulling (EFG and Cz) were demonstrated for the first time for semiconductor grade TlBr material. The viability of each process along with the associated challenges for TlBr growth has been discussed. The purity of the TlBr crystals along with its crystalline and electronic properties were analyzed and correlated with the growth techniques. Uncorrected 662 keV energy resolutions around 2% were obtained from 5 mm x 5 mm x 10 mm TlBr devices with virtual Frisch-grid configuration.

  6. Determination of the spectroscopic properties of indium bromide

    Science.gov (United States)

    Mulders, H. C. J.; Rijke, A. J.; Haverlag, M.; Kroesen, G. M. W.

    2011-07-01

    To develop a more efficient plasma light source, molecules are considered as the prime source of radiation because they can potentially avoid the conversion losses of the low-pressure mercury lamp as well as the thermal losses of the high-pressure mercury lamps. A candidate to serve as the prime radiator in such a lamp could be indium bromide, but spectroscopic data to assess its aptitude are largely unavailable. To increase the knowledge of the spectroscopic properties of these molecules and InBr in particular, an experiment was designed to acquire this information. Laser-induced fluorescence was used to study the radiative properties of InBr for lighting purposes. Using an innovative method to interpret the measured data, detection--excitation (detex) plots, more information can be obtained from the spectra. Also the effect of a background gas and plasma was investigated for both a capacitive and an inductive plasma. Mainly the electronic A-state of InBr was investigated. Results include newly identified rotational transitions, vibrational constants, rotational constants for different vibrational levels, band head wave numbers and Franck-Condon factors for various vibrational transitions.

  7. Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles

    Directory of Open Access Journals (Sweden)

    M. Wachsmuth

    2002-01-01

    Full Text Available Uptake of HOBr on sea salt aerosol, sea salt brine or ice is believed to be a key process providing a source of photolabile bromine (Br2 and sustaining ozone depletion cycles in the Arctic troposphere. In the present study, uptake of HOBr on sodium bromide (NaBr aerosol particles was investigated at an extremely low HOBr concentration of 300 cm-3 using the short-lived radioactive isotopes 83-86Br. Under these conditions, at maximum one HOBr molecule was taken up per particle. The rate of uptake was clearly limited by the mass accommodation coefficient, which was calculated to be 0.6 ± 0.2. This value is a factor of 10 larger than estimates used in earlier models. The atmospheric implications are discussed using the box model "MOCCA'', showing that the increase of the accommodation coefficient of HOBr by a factor of 10 only slightly affects net ozone loss, but significantly increases chlorine release.

  8. Micellization of cetyltrimethylammonium bromide: effect of small chain Bola electrolytes.

    Science.gov (United States)

    Pan, Animesh; Sil, Pallabi; Dutta, Sounak; Das, Prasanta Kumar; Bhattacharya, Subhash Chandra; Rakshit, Animesh Kumar; Aswal, Vinod Kumar; Moulik, Satya Priya

    2014-03-20

    Sodium dicarboxylates (or Bola salts) with methylene spacers 0, 2, 4, 6, 8, and 10 were studied in aqueous solution to investigate their influence on the micellization of cetyltrimethylammonium bromide (CTAB). Since bolas with spacer length ≤12 are known not to micellize in general, the herein used sodium dicarboxylates were treated as 2:1 amphiphilic electrolytes which reduced surface tension of water (except sodium oxalate with zero spacer) without self-association. Their concentration dependent conductance was also linear without breaks. The bolas affected the micellization of CTAB but acted like salts to decrease its CMC. Their combinations did not form bilayer aggregates as found in vesicles. Nevertheless, they synergistically interacted with CTAB at the air/water interface as revealed from Rosen's thermodynamic model. Hydrodynamic radius (Rh), Zeta-potential (ζ), and electrical double layer behavior of bola interacted CTAB micelles were assessed. From SANS measurements, micelle shape, shape parameters, aggregation number (Nagg), surface charge of the bola influenced CTAB micelles were also determined. NMR study as well supported the non-mixing of bolas with the CTAB micelles. They interacted in solution like "amphiphilic electrolytes" to influence the surface and micelle forming properties of CTAB.

  9. Methyl bromide determination in selected foods by headspace technique.

    Science.gov (United States)

    Daft, J L

    1993-01-01

    A headspace method used earlier for determining methyl bromide (MB) in assorted nuts and peanut butters has been successfully applied to other foods that could potentially contain traces of this toxic fumigant. The foods tested include 63 off-the-shelf spices and seasonings, 83 table-ready items (grain-based, dried, or highly seasoned), 30 dried fruits and trail mixes, and 38 oil-based items (oil-seeds, cooking oils, or spicy oil-based dressings). Sample headspace gas is produced by blending < or = 50 g sample in 250 +/- 50 mL aqueous solution in a sealed 1000 mL blender cup. After equilibration at 25 degrees C, the headspace is sampled with a gas-tight syringe and injected into a dual column-dual detector gas chromatograph. One determination is made with a 20% OV-101 packed column and a 63Ni electron capture detector (ECD), the other with a GS-Q wide-bore capillary column and a Hall electrolytic conductivity detector (HECD). Of the approximately 200 samples tested, none contained detectable MB residue at a quantitation limit < 100 ng/g sample. All fortified samples yielded MB recovery. Samples were fortified at levels ranging from 78 to 3250 ng MB/g. Recoveries ranged from a mean high of 56% for spices and seasonings to a mean low of 30% for oil-based foods. The overall recovery and CV, including the results from assorted nuts and peanut butters, were 46 and 33%, respectively.

  10. Chloride, bromide and iodide scintillators with europium doping

    Science.gov (United States)

    Zhuravleva, Mariya; Yang, Kan

    2014-08-26

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  11. Exploring the contribution of efflux on the resistance to fluoroquinolones in clinical isolates of Staphylococcus aureus

    LENUS (Irish Health Repository)

    Costa, Sofia SANTOS

    2011-10-27

    Abstract Background Antimicrobial resistance mediated by efflux systems is still poorly characterized in Staphylococcus aureus, despite the description of several efflux pumps (EPs) for this bacterium. In this work we used several methodologies to characterize the efflux activity of 52 S. aureus isolates resistant to ciprofloxacin collected in a hospital in Lisbon, Portugal, in order to understand the role played by these systems in the resistance to fluoroquinolones. Results Augmented efflux activity was detected in 12 out of 52 isolates and correlated with increased resistance to fluoroquinolones. Addition of efflux inhibitors did not result in the full reversion of the fluoroquinolone resistance phenotype, yet it implied a significant decrease in the resistance levels, regardless of the type(s) of mutation(s) found in the quinolone-resistance determining region of grlA and gyrA genes, which accounted for the remaining resistance that was not efflux-mediated. Expression analysis of the genes coding for the main efflux pumps revealed increased expression only in the presence of inducing agents. Moreover, it showed that not only different substrates can trigger expression of different EP genes, but also that the same substrate can promote a variable response, according to its concentration. We also found isolates belonging to the same clonal type that showed different responses towards drug exposure, thus evidencing that highly related clinical isolates may diverge in the efflux-mediated response to noxious agents. The data gathered by real-time fluorometric and RT-qPCR assays suggest that S. aureus clinical isolates may be primed to efflux antimicrobial compounds. Conclusions The results obtained in this work do not exclude the importance of mutations in resistance to fluoroquinolones in S. aureus, yet they underline the contribution of efflux systems for the emergence of high-level resistance. All together, the results presented in this study show the potential

  12. Ezetimibe Promotes Brush Border Membrane-to-Lumen Cholesterol Efflux in the Small Intestine.

    Directory of Open Access Journals (Sweden)

    Takanari Nakano

    Full Text Available Ezetimibe inhibits Niemann-Pick C1-like 1 (NPC1L1, an apical membrane cholesterol transporter of enterocytes, thereby reduces intestinal cholesterol absorption. This treatment also increases extrahepatic reverse cholesterol transport via an undefined mechanism. To explore this, we employed a trans-intestinal cholesterol efflux (TICE assay, which directly detects circulation-to-intestinal lumen 3H-cholesterol transit in a cannulated jejunal segment, and found an increase of TICE by 45%. To examine whether such increase in efflux occurs at the intestinal brush border membrane(BBM-level, we performed luminal perfusion assays, similar to TICE but the jejunal wall was labelled with orally-given 3H-cholesterol, and determined elevated BBM-to-lumen cholesterol efflux by 3.5-fold with ezetimibe. Such increased efflux probably promotes circulation-to-lumen cholesterol transit eventually; thus increases TICE. Next, we wondered how inhibition of NPC1L1, an influx transporter, resulted in increased efflux. When we traced orally-given 3H-cholesterol in mice, we found that lumen-to-BBM 3H-cholesterol transit was rapid and less sensitive to ezetimibe treatment. Comparison of the efflux and fractional cholesterol absorption revealed an inverse correlation, indicating the efflux as an opposite-regulatory factor for cholesterol absorption efficiency and counteracting to the naturally-occurring rapid cholesterol influx to the BBM. These suggest that the ezetimibe-stimulated increased efflux is crucial in reducing cholesterol absorption. Ezetimibe-induced increase in cholesterol efflux was approximately 2.5-fold greater in mice having endogenous ATP-binding cassette G5/G8 heterodimer, the major sterol efflux transporter of enterocytes, than the knockout counterparts, suggesting that the heterodimer confers additional rapid BBM-to-lumen cholesterol efflux in response to NPC1L1 inhibition. The observed framework for intestinal cholesterol fluxes may provide ways to

  13. Photocatalytic degration kinetics in Rhodamine B dye degradation with poriferous TiO2 photocatalyst

    Science.gov (United States)

    Wang, Zheng-Ping; Jiao, Cai-Shan; Chen, Xing-Juan

    2006-06-01

    A type of poriferous TiO2 material was prepared using cetyl trimethyl ammonium bromide as a template agent and butyl tetra titanate as a precursor. Through studying the photocatalytic kinetic activity of Rhodamine B photocatalytic degradation reaction with a UV-1601PC ultraviolet-visible spectrophotometer, the photocatalytic degradation process of Rhodamine B was found to not correspond to the first-order kinetic process completely. According to the reaction phenomenon, the photocatalytic degradation process of Rhodamine B with poriferous TiO2 involved two irrevesible reactions. The kinetic model was tested using experimental data.

  14. A comparison of the effect of intranasal desmopressin and intramuscular hyoscine N-butyl bromide combination with intramuscular hyoscine N-butyl bromide alone in acute renal colic

    Directory of Open Access Journals (Sweden)

    Abdol-Reza Kheirollahi

    2010-01-01

    Full Text Available Background: Patients with acute renal colic usually require immediate diagnosis and treatment. In this clinical trial analgesic effect of hyoscine N-butyl bromide and desmopressin combination in comparison with hyoscine N-butyl bromide alone in patients with acute renal colic induced by urinary stones was assessed. Methods: The study included 114 patients randomly allocated in two groups (A and B. Patients in group A received 20 mg intramuscular hyoscine N-butyl bromide at admission time and patients in group B received 20 μg of intranasal desmopressin in combination with 20 mg intramuscular hyoscine N-butyl bromide. A visual analogue scale (VAS; a 10-cm horizontal scale ranging from "zero or no pain" to "10 or unbearable pain" was hired to assess the patients′ pain severity at baseline, 30 and 60 minutes after the treatments. Results: On admission, the pain level was similar in both groups (group A: 8.95 ± 0.11 and group B: 8.95 ± 0.12. In group A, the mean of pain level showed a decrease after 30 minutes (group A: 7.26 ± 0.25 and group B: 5.95 ± 0.28 but further decreasing did not occur; however in group B, the pain consistently decreased and the mean after 60 minutes was significantly decreased (group A: 6.80 ± 0.31 and group B: 3.71 ± 0.31. No side effects were detected in this study. Conclusions: The combination of hyoscine N-butyl bromide and desmopressin is more effective than hyoscine N-butyl bromide alone in patients with renal colic. Further studies are recommended to validate these findings and compare the different doses of desmopressin.

  15. PKCβ Inhibitors Attenuate Amphetamine-Stimulated Dopamine Efflux.

    Science.gov (United States)

    Zestos, Alexander G; Mikelman, Sarah R; Kennedy, Robert T; Gnegy, Margaret E

    2016-06-15

    Amphetamine abuse afflicts over 13 million people, and there is currently no universally accepted treatment for amphetamine addiction. Amphetamine serves as a substrate for the dopamine transporter and reverses the transporter to cause an increase in extracellular dopamine. Activation of the beta subunit of protein kinase C (PKCβ) enhances extracellular dopamine in the presence of amphetamine by facilitating the reverse transport of dopamine and internalizing the D2 autoreceptor. We previously demonstrated that PKCβ inhibitors block amphetamine-stimulated dopamine efflux in synaptosomes from rat striatum in vitro. In this study, we utilized in vivo microdialysis in live, behaving rats to assess the effect of the PKCβ inhibitors, enzastaurin and ruboxistaurin, on amphetamine-stimulated locomotion and increases in monoamines and their metabolites. A 30 min perfusion of the nucleus accumbens core with 1 μM enzastaurin or 1 μM ruboxistaurin reduced efflux of dopamine and its metabolite 3-methoxytyramine induced by amphetamine by approximately 50%. The inhibitors also significantly reduced amphetamine-stimulated extracellular levels of norepinephrine. The stimulation of locomotor behavior by amphetamine, measured simultaneously with the analytes, was comparably reduced by the PKCβ inhibitors. Using a stable isotope label retrodialysis procedure, we determined that ruboxistaurin had no effect on basal levels of dopamine, norepinephrine, glutamate, or GABA. In addition, normal uptake function through the dopamine transporter was unaltered by the PKCβ inhibitors, as measured in rat synaptosomes. Our results support the utility of using PKCβ inhibitors to reduce the effects of amphetamine.

  16. Engineering microbial biofuel tolerance and export using efflux pumps

    Science.gov (United States)

    Dunlop, Mary J; Dossani, Zain Y; Szmidt, Heather L; Chu, Hou Cheng; Lee, Taek Soon; Keasling, Jay D; Hadi, Masood Z; Mukhopadhyay, Aindrila

    2011-01-01

    Many compounds being considered as candidates for advanced biofuels are toxic to microorganisms. This introduces an undesirable trade-off when engineering metabolic pathways for biofuel production because the engineered microbes must balance production against survival. Cellular export systems, such as efflux pumps, provide a direct mechanism for reducing biofuel toxicity. To identify novel biofuel pumps, we used bioinformatics to generate a list of all efflux pumps from sequenced bacterial genomes and prioritized a subset of targets for cloning. The resulting library of 43 pumps was heterologously expressed in Escherichia coli, where we tested it against seven representative biofuels. By using a competitive growth assay, we efficiently distinguished pumps that improved survival. For two of the fuels (n-butanol and isopentanol), none of the pumps improved tolerance. For all other fuels, we identified pumps that restored growth in the presence of biofuel. We then tested a beneficial pump directly in a production strain and demonstrated that it improved biofuel yields. Our findings introduce new tools for engineering production strains and utilize the increasingly large database of sequenced genomes. PMID:21556065

  17. Methyl Bromide Buffer Zone Distances for Commodity and Structural Fumigation: Treatment Longer than 8 Hours

    Science.gov (United States)

    This document contains buffer zone tables required by certain methyl bromide commodity fumigant product labels that refer to Buffer Zone Lookup Tables located at epa.gov/pesticide-registration/mbcommoditybuffer on the label.

  18. Methyl Bromide Buffer Zone Distances for Commodity and Structural Fumigation: Treatment 8 Hours or Less

    Science.gov (United States)

    This document contains buffer zone tables required by certain methyl bromide commodity fumigant product labels that refer to Buffer Zone Lookup Tables located at epa.gov/pesticide-registration/mbcommoditybuffer on the label.

  19. Effect of Methyl Bromide on Mycorrhizae and Growth of Sweetgum Seedlings

    Science.gov (United States)

    T. H. Filer; E. R. Toole

    1968-01-01

    Fumigation of nursery beds with methyl bromide improved sweetgum, growth by reducing the population of soil-inhabiting pathogens . Although mycorrhizal fungi were reduced, sufficient inoculum survived for rapid mycorrhizal development

  20. Net cholesterol efflux capacity of HDL enriched serum and coronary atherosclerosis in rheumatoid arthritis.

    Science.gov (United States)

    Ormseth, Michelle J; Yancey, Patricia G; Yamamoto, Suguru; Oeser, Annette M; Gebretsadik, Tebeb; Shintani, Ayumi; Linton, MacRae F; Fazio, Sergio; Davies, Sean S; Roberts, L Jackson; Vickers, Kasey C; Raggi, Paolo; Kon, Valentina; Stein, C Michael

    2016-12-01

    Cardiovascular (CV) risk is increased in patients with rheumatoid arthritis (RA), but not fully explained by traditional risk factors such as LDL and HDL cholesterol concentrations. The cholesterol efflux capacity of HDL may be a better CV risk predictor than HDL concentrations. We hypothesized that HDL's cholesterol efflux capacity is impaired and inversely associated with coronary atherosclerosis in patients with RA. We measured the net cholesterol efflux capacity of apolipoprotein B depleted serum and coronary artery calcium score in 134 patients with RA and 76 control subjects, frequency-matched for age, race and sex. The relationship between net cholesterol efflux capacity and coronary artery calcium score and other clinical variables of interest was assessed in patients with RA. Net cholesterol efflux capacity was similar among RA (median [IQR]: 34% removal [28, 41%]) and control subjects (35% removal [27%, 39%]) (P=0.73). In RA, increasing net cholesterol efflux capacity was not significantly associated with decreased coronary calcium score (OR=0.78 (95% CI 0.51-1.19), P=0.24, adjusted for age, race and sex, Framingham risk score and presence of diabetes). Net cholesterol efflux capacity was not significantly associated with RA disease activity score, C-reactive protein, urinary F2-isoprostanes, or degree of insulin resistance in RA. Net cholesterol efflux capacity is not significantly altered in patients with relatively well-controlled RA nor is it significantly associated with coronary artery calcium score.

  1. The macrophage and its related cholesterol efflux as a HDL function index in atherosclerosis.

    Science.gov (United States)

    Yamamoto, Suguru; Narita, Ichiei; Kotani, Kazuhiko

    2016-06-01

    The macrophage and its related cholesterol efflux are considered to be a key player in atherosclerotic formation in relation to the function of high-density lipoprotein (HDL). The HDL function can be evaluated by the reaction between lipid-loaded macrophages and lipid-acceptors in the HDL fraction from the plasma, apolipoprotein B-depleted serum, and/or whole serum/plasma. Recent studies have reported that an impaired cholesterol efflux of HDL is observed in patients with cardiometabolic diseases, such as dyslipidemia, diabetes mellitus, and chronic kidney disease. A population-based cohort study has reported an inverse association between the cholesterol efflux capacity of HDL and the incidence of atherosclerotic disease, regardless of the serum HDL-cholesterol level. Moreover, in this paper, when we summarized several clinical interventional studies of statin treatment that examined cholesterol efflux, a potential increase in the efflux in patients treated with statins was implied. However, the effect was not fully defined in the current situation because of the small sample sizes, lack of a unified protocol for measuring the efflux, and short-term intervention periods without cardiovascular outcomes in available studies. Further investigation is necessary to determine the effect of drugs on cholesterol efflux. With additional advanced studies, cholesterol efflux is a promising laboratory index to understand the HDL function. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Nanoparticles as Efflux Pump and Biofilm Inhibitor to Rejuvenate Bactericidal Effect of Conventional Antibiotics

    Science.gov (United States)

    Gupta, Divya; Singh, Ajeet; Khan, Asad U.

    2017-07-01

    The universal problem of bacterial resistance to antibiotic reflects a serious threat for physicians to control infections. Evolution in bacteria results in the development of various complex resistance mechanisms to neutralize the bactericidal effect of antibiotics, like drug amelioration, target modification, membrane permeability reduction, and drug extrusion through efflux pumps. Efflux pumps acquire a wide range of substrate specificity and also the tremendous efficacy for drug molecule extrusion outside bacterial cells. Hindrance in the functioning of efflux pumps may rejuvenate the bactericidal effect of conventional antibiotics. Efflux pumps also play an important role in the exclusion or inclusion of quorum-sensing biomolecules responsible for biofilm formation in bacterial cells. This transit movement of quorum-sensing biomolecules inside or outside the bacterial cells may get interrupted by impeding the functioning of efflux pumps. Metallic nanoparticles represent a potential candidate to block efflux pumps of bacterial cells. The application of nanoparticles as efflux pump inhibitors will not only help to revive the bactericidal effect of conventional antibiotics but will also assist to reduce biofilm-forming capacity of microbes. This review focuses on a novel and fascinating application of metallic nanoparticles in synergy with conventional antibiotics for efflux pump inhibition.

  3. Computational model for speed of efflux in liquids | Ikata | Journal of ...

    African Journals Online (AJOL)

    We have looked at the efflux of a viscous liquid from an orifice. Assuming the steady flow of a Newtonian fluid, a model for the energy loss due to viscous shearing stress is derived, and a first-order non-linear ordinary differential equation of second degree is obtained for the speed of efflux. Numerically, the equation is ...

  4. Biases of chamber methods for measuring soil CO2 efflux demonstrated with a laboratory apparatus.

    Science.gov (United States)

    S. Mark Nay; Kim G. Mattson; Bernard T. Bormann

    1994-01-01

    Investigators have historically measured soil CO2 efflux as an indicator of soil microbial and root activity and more recently in calculations of carbon budgets. The most common methods estimate CO2 efflux by placing a chamber over the soil surface and quantifying the amount of CO2 entering the...

  5. Rapid sediment accumulation results in high methane effluxes from coastal sediments

    NARCIS (Netherlands)

    Egger, M.J.; Lenstra, W.K.; Jong, Dirk; Meysman, Filip; Sapart, C.J.; van der Veen, C.; Röckmann, Thomas; Gonzalez, Santiago; Slomp, C.P.

    2016-01-01

    Globally, the methane (CH4) efflux from the ocean to the atmosphere is small, despite high rates of CH4 production in continental shelf and slope environments. This low efflux results from the biological removal of CH4 through anaerobic oxidation with sulfate in marine sediments. In some settings,

  6. Contribution of Cdc42 to cholesterol efflux in fibroblasts from Tangier disease and Werner syndrome.

    Science.gov (United States)

    Hirano, Ken-ichi; Ikegami, Chiaki; Zhang, Zhongyan

    2008-01-01

    Atherosclerotic cardiovascular disease is a life-threatening disorder. Cholesterol efflux from the cells is the rate-limiting step in regulating the intracellular cholesterol content as well as raft structure in the plasma membrane. The defect of cholesterol efflux leads to the development of atherosclerosis. Tangier disease (TD), a hereditary high-density lipoprotein deficiency, is characterized by the presence of defective cellular cholesterol efflux. Using the cDNA subtraction technique, we found that expression of Cdc42 was decreased markedly in fibroblasts and macrophages from patients with TD. Madin-Darby canine kidney cells expressing the dominant-negative form of Cdc42 had a reduced lipid efflux; inversely, cells expressing the active form had increased efflux. Furthermore, we found that cellular lipid efflux was defective and Cdc42 was reduced in fibroblasts from a premature aging disorder, Werner syndrome. Complementation experiments using an adenovirus carrying wild-type Cdc42 successfully corrected impaired lipid efflux in Werner syndrome cells. We concluded that Cdc42 may play important roles in cellular cholesterol efflux and that dysregulation of this type of RhoGTPase might lead to the development of atherosclerotic cardiovascular disease.

  7. High efflux pump activity and gene expression at baseline linked to ...

    African Journals Online (AJOL)

    Phenotypic TB drug resistance, also known as drug tolerance, has been previously attributed to slowed bacterial growth in vivo. The increased activity and expression of efflux systems can lower the intracellular concentration of many antibiotics thus reducing their efficacy. We hypothesized that efflux pump activation and ...

  8. ESTIMATE OF CO2 EFFLUX OF SOIL, OF A TRANSITION FOREST IN NORTHWEST OF MATO GROSSO STATE, USING MULTIPLE REGRESSION

    National Research Council Canada - National Science Library

    Carla Maria Abido Valentini; Mariano Martínez Espinosa; Sérgio Roberto de Paulo

    2008-01-01

    .... Considering that soil CO2 efflux is the greater component of the carboncycle of the biosphere, this work found an equation for estimating the soil CO2 efflux of an area of the Transition Forest...

  9. [Advantages of oxythiamine bromide as a specific inhibitor of activity of thiamine-dependent enzymes].

    Science.gov (United States)

    Oparin, D A; Zimatkina, T I; Ostrovskiĭ, Iu M

    1987-01-01

    Production of hydrogen bromide salt of hydroxythiamine (Ht. HBr) from thiamine bromide was developed its toxic and inhibitory properties towards transketolase and pyruvate dehydrogenase were studied as compared with commercial preparation hydroxythiamine chloride (HT. HCl). As compared with HT. HCl, synthesis of HT. HBr was more simple, the higher yield and purity of the end product were achieved. At the same time, the preparation was less toxic and exhibited the antivitaminous activity similar to the commercial chloride form.

  10. Tribromoisocyanuric acid/triphenylphosphine: a new system for conversion of alcohols into alkyl bromides

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Vitor S.C. de; Mattos, Marcio C.S. de, E-mail: mmattos@iq.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Quimica. Departamento de Quimica Organica

    2014-05-15

    An efficient and facile method has been developed for the conversion of alcohols into alkyl bromides under neutral conditions using tribromoisocyanuric acid and triphenylphosphine (molar ratio 1.0:0.7:2.0, alcohol/tribromoisocyanuric acid/triphenylphosphine) in dichloromethane at room temperature. This method can be applied for the conversion of primary, secondary, benzilic and allylic alcohols, and their corresponding bromides are obtained in 67-82 % yield. Tertiary alcohols do not react under these conditions. (author)

  11. Kinetic buffers.

    Science.gov (United States)

    Alibrandi, Giuseppe; Fabbrizzi, Luigi; Licchelli, Maurizio; Puglisi, Antonio

    2015-01-12

    This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Overestimation of closed-chamber soil CO2 effluxes at low atmospheric turbulence

    DEFF Research Database (Denmark)

    Brændholt, Andreas; Larsen, Klaus Steenberg; Ibrom, Andreas

    2017-01-01

    Soil respiration (R-s) is an important component of ecosystem carbon balance, and accurate quantification of the diurnal and seasonal variation of R-s is crucial for a correct interpretation of the response of R-s to biotic and abiotic factors, as well as for estimating annual soil CO2 efflux rates......, such that the highest effluxes were now observed during daytime, and also led to a substantial decrease in the estimated annual soil CO2 efflux.By installing fans to produce continuous turbulent mixing of air around the soil chambers, we tested the hypothesis that overestimation of soil CO2 effluxes during low u(*) can...... atmospheric turbulence conditions. Other possible effects from using fans during soil CO2 efflux measurements are discussed. In conclusion, periods with low atmospheric turbulence may provide a significant source of error in R-s rates estimated by the use of closed-chamber tech-niques and erroneous data must...

  13. Stable room-temperature thallium bromide semiconductor radiation detectors

    Science.gov (United States)

    Datta, A.; Fiala, J.; Becla, P.; Motakef, Shariar

    2017-10-01

    Thallium bromide (TlBr) is a highly efficient ionic semiconductor with excellent radiation detection properties. However, at room temperature, TlBr devices polarize under an applied electric field. This phenomenon not only degrades the charge collection efficiency of the detectors but also promotes chemical reaction of the metal electrodes with bromine, resulting in an unstable electric field and premature failure of the device. This drawback has been crippling the TlBr semiconductor radiation detector technology over the past few decades. In this exhaustive study, this polarization phenomenon has been counteracted using innovative bias polarity switching schemes. Here the highly mobile Br- species, with an estimated electro-diffusion velocity of 10-8 cm/s, face opposing electro-migration forces during every polarity switch. This minimizes the device polarization and availability of Br- ions near the metal electrode. Our results indicate that it is possible to achieve longer device lifetimes spanning more than 17 000 h (five years of 8 × 7 operation) for planar and pixelated radiation detectors using this technique. On the other hand, at constant bias, 2500 h is the longest reported lifetime with most devices less than 1000 h. After testing several biasing switching schemes, it is concluded that the critical bias switching frequency at an applied bias of 1000 V/cm is about 17 μHz. Using this groundbreaking result, it will now be possible to deploy this highly efficient room temperature semiconductor material for field applications in homeland security, medical imaging, and physics research.

  14. Stable room-temperature thallium bromide semiconductor radiation detectors

    Directory of Open Access Journals (Sweden)

    A. Datta

    2017-10-01

    Full Text Available Thallium bromide (TlBr is a highly efficient ionic semiconductor with excellent radiation detection properties. However, at room temperature, TlBr devices polarize under an applied electric field. This phenomenon not only degrades the charge collection efficiency of the detectors but also promotes chemical reaction of the metal electrodes with bromine, resulting in an unstable electric field and premature failure of the device. This drawback has been crippling the TlBr semiconductor radiation detector technology over the past few decades. In this exhaustive study, this polarization phenomenon has been counteracted using innovative bias polarity switching schemes. Here the highly mobile Br− species, with an estimated electro-diffusion velocity of 10−8 cm/s, face opposing electro-migration forces during every polarity switch. This minimizes the device polarization and availability of Br− ions near the metal electrode. Our results indicate that it is possible to achieve longer device lifetimes spanning more than 17 000 h (five years of 8 × 7 operation for planar and pixelated radiation detectors using this technique. On the other hand, at constant bias, 2500 h is the longest reported lifetime with most devices less than 1000 h. After testing several biasing switching schemes, it is concluded that the critical bias switching frequency at an applied bias of 1000 V/cm is about 17 μHz. Using this groundbreaking result, it will now be possible to deploy this highly efficient room temperature semiconductor material for field applications in homeland security, medical imaging, and physics research.

  15. Subsurface drip application of alternative fumigants to methyl bromide for controlling nematodes in replanted grapevines.

    Science.gov (United States)

    Cabrera, J Alfonso; Wang, Dong; Schneider, Sally M; Hanson, Bradley D

    2012-05-01

    Many California grape growers use preplant fumigation to ensure uniform and healthy grapevine establishment in replant situations. A field study was conducted to evaluate the performance of subsurface drip-applied chemical alternatives to methyl bromide on plant-parasitic nematodes, plant vigor and fruit yield during the 6 year period following replanting. Subsurface drip fumigation with 1,3-dichloropropene plus chloropicrin and with iodomethane plus chloropicrin had generally similar nematicide activity as methyl bromide in three grape types, while sodium azide was less effective. The combination of 1,3-dichloropropene plus chloropicrin enhanced vine vigor similarly to methyl bromide. However, all plots treated with alternative fumigants produced less fruit yield than methyl bromide over the 4 years of evaluation. Subsurface drip fumigation with alternative chemicals to methyl bromide generally provided adequate management of plant-parasitic nematodes during the vine establishment period. However, further research is required to increase the performance of alternative chemicals against other components of the replant problem, as grape yield in vines grown in the alternative treatments was lower than in methyl bromide. Copyright © 2011 Society of Chemical Industry.

  16. Trihalomethanes and haloacetic acid species from the chlorination of algal organic matter and bromide.

    Science.gov (United States)

    Wei, Y Y; Liu, Y; Dai, R H; Liu, X; Wu, J J; Shi, Z; Ren, J; Zhang, Y

    2011-01-01

    Bromide and algal pollution are important factors influencing disinfection byproduct (DBP) formation and speciation in reservoir water in coastal areas. In this study, the chlorination of model algal cellular compounds (bovine serum albumin, fish oil and starch), Microcystis aeruginosa and its extra-cellular organic matter (EOM) were conducted in the absence and presence of bromide. The main aim of the present study is to explore their potential as precursors for trihalomethanes (THMs) and haloacetic acid (HAAs) speciation upon chlorination in the presence of bromide. The results showed that all brominated THMs species were generated, whereas only bromochloroacetic acid (BCAA) or/and dibromoacetic acid (DBAA) was/were produced as for brominated HAAs (Br-HAAs) from the three model compounds in the presence of bromide. The effect of bromide on Br-HAAs speciation upon fish oil chlorination was more evident than with BSA and starch. There was a good correlation between the species predicted from the model compounds and those obtained from specific algal species. Br-HAAs and Br-THMs species from Microcystis aeruginosa cells or EOM were the same as those from bovine serum albumin in the presence of bromide.

  17. Nitrogen Fertilization Modifies the Phenology of Ground CO2 Efflux in a Boreal Scots Pine Forest

    Science.gov (United States)

    Marshall, J. D.; Näsholm, T.; Linder, S.; Tarvainen, L.; Peichl, M.; Lundmark, T.

    2015-12-01

    Problems with the extraction of ecosystem respiration rates from eddy covariance data have led to renewed interest in chamber-based estimates of CO2 efflux from near the ground surface. However, chamber measurements frequently have their own issues. Here we describe the results of a study using large (≈2 m radius), transparent chambers over intact ground vegetation to describe the net efflux of CO2 and its environmental controls during the growing season at Rosinedal, a research site in northern Sweden. Measurements were made at thirty-minute intervals over the course of three growing seasons in a heavily fertilized and an unfertilized Scots pine stand. Ammonium nitrate was added at rates of 100 kg N ha-1 for the first five years, after which the rate was halved but the additions continued. The CO2 efflux results were simultaneously fitted to a nonlinear model describing the exponential increase in dark efflux with temperature, the Michaelis-Menten saturation of light-driven CO2 uptake in photosynthesis, the reduction in efflux due to soil drying, and a residual term that we ascribe to weekly shifts in the photosynthate partitioning of canopy trees to belowground processes. We found the expected exponential increase in dark efflux with temperature, however the net efflux in daytime was often negative, reflecting the high GPP of the ground vegetation, especially in dense canopies of bilberry (Vaccinium myrtillus L.). There was a clear reduction in dark efflux under dry conditions. The empirical phenology parameters increased sharply in early July, around the time that leaf expansion and rapid cambial growth were completed. This increase was more pronounced on the control plot than on the fertilized plot, consistent with expectations based on the notion that N fertilization should favor aboveground partitioning. The empirical "partitioning coefficient" shifted net efflux by nearly as much as the seasonal temperature range. Dark efflux of CO2 was nearly halved as a

  18. Control of insects with fumigants at low temperatures: toxicity of mixtures of methyl bromide and acrylonitrile to three species of insects

    Energy Technology Data Exchange (ETDEWEB)

    Bond, E.J.; Buckland, C.T.

    1976-12-15

    Acrylonitrile can be mixed with methyl bromide to increase toxicity so that the quantity of methyl bromide required for control of Sitophilus granarius (L.), Tenebrio molitor L., and Tribolium confusum Jacquelin duval is reduced by one half. Mixtures of methyl bromide and acrylonitrile are considerably more effective at low temperatures than methyl bromide alone.

  19. Perspective on plasma membrane cholesterol efflux and spermatozoal function

    Directory of Open Access Journals (Sweden)

    Dhastagir Sultan Sheriff

    2010-01-01

    techniques for enhancing fertility, identifying and treating certain forms of male infertility, and preventing conception. One remarkable insight is the importance of membrane cholesterol efflux in initiating transmembrane signaling events that confer fertilization competence. The identity of the physiologically relevant cholesterol acceptors and modulators of cholesterol efflux is therefore of great interest. Still, it is clear that cholesterol efflux represents only a part of this story. The involvement of phospholipid translocation in mediating dynamic changes in the membrane, rendering it conducive to transmembrane signaling, and the modulation of membrane components of signal transduction cascades by cholesterol or phospholipids will yield important insights into the links between environmental sensing and transmembrane signaling in the sperm. Understanding the membrane molecular events will ultimately provide new and exciting areas of investigation for the future.

  20. 2,6-Bis(oxazolinyl)phenylnickel(II) Bromide and 2,6-Bis(ketimine)phenylnickel(II) Bromide: Synthesis, Structural Features, and Redox Properties

    NARCIS (Netherlands)

    Stol, M.; Snelders, D.J.M.; Godbole, M.D.; Havenith, R.W.A.; Haddleton, D.M.; Clarkson, G.; Lutz, M.; Spek, A.L.; van Klink, G.P.M.; van Koten, G.

    2007-01-01

    2,6-Bis(oxazolinyl)phenylnickel bromide complexes [NiBr(R,R'-Phebox)] (2) were synthesized via two synthetic routes (A and B). In route A, selective bis-ortho lithiation of [R,R'-PheboxBr], followed by a transmetalation reaction with [NiBr2(PEt3)2], yielded not only complexes 2 with an

  1. Calibration and analysis of soil carbon efflux estimates with closed chambers at Forsmark and Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern (Dept. of Physical Geography and Ecosystem Analysis, Lund Univ., Lund (SE))

    2006-08-15

    The Forsmark and the Laxemar investigation areas are examined by the Swedish Nuclear Fuel and Waste Management Co. for a possible construction of a deep repository for nuclear waste. In the case of a future leakage of waste, the radioactive isotopes could end up in the ecosystems above the repository. The fate of the radionuclides and their possible radiological impacts are then highly determined by ecosystem carbon cycling. An important part of the carbon cycling is the soil carbon effluxes, and in the investigation areas soil carbon effluxes have been examined with the closed chamber technique. This paper is divided into two parts. Firstly, there were problems with the equipment measuring the soil carbon dioxide efflux, and the first part is a description of the problem, how it was corrected and its possible causes. The second part is a manual in how to analyse data and calculate annual estimates of soil carbon efflux. The field measurement by the EGM-4 is just an occasional estimate of the soil carbon efflux at a certain spot and at a certain point in time. To make an interpretation of the measurements, it is essential to analyse the data and to temporally extrapolate them. It is necessary to prepare the raw data for the analysis. The problems with the EGM-4 doing the measurements at the Forsmark and the Laxemar investigation area makes it necessary to correct the data taken up by this EGM-4. The data should also be separated into soil respiration and gross primary production (GPP). Soil carbon dioxide effluxes should be changed to soil carbon effluxes. Soil carbon effluxes are strongly controlled by abiotic factors; temperature is the main factor to influence soil respiration and photosynthetically active radiation (PAR) and air temperature are the main factors to influence GPP. Regression with soil respiration against temperature and with GPP against PAR or temperature can therefore be done. These equations can then be used on datasets with temperature and PAR

  2. Efflux time of soap bubbles and liquid spheres.

    Science.gov (United States)

    Grosse, A V

    1967-06-02

    The efflux time, T, of gas from soap bubbles of radius, R, through their blow tube of length, 1, and radius, p, is given by the equation see pdf for equation where eta is the viscosity of the gas and omicron the surface tension of the bubble solution, all in centimeter-gram-second units. Similar relations between time and diameter were established for the flow from one bubble to another or from one bubble within another. The same relations hold for the flow of liquid spheres, suspended in another liquid of equal density, following Plateau's classic method. They have been extended to the flow of spheres to cylinders and catenoids of rotation. In all these cases the driving force is the surface or interfacial tension, creating an excess pressure as defined by Laplace's equation.

  3. Moderate hyperventilation during intravenous anesthesia increases net cerebral lactate efflux.

    Science.gov (United States)

    Grüne, Frank; Kazmaier, Stephan; Sonntag, Hans; Stolker, Robert Jan; Weyland, Andreas

    2014-02-01

    Hyperventilation is known to decrease cerebral blood flow (CBF) and to impair cerebral metabolism, but the threshold in patients undergoing intravenous anesthesia is unknown. The authors hypothesized that reduced CBF associated with moderate hyperventilation might impair cerebral aerobic metabolism in patients undergoing intravenous anesthesia. Thirty male patients scheduled for coronary surgery were included in a prospective, controlled crossover trial. Measurements were performed under fentanyl-midazolam anesthesia in a randomized sequence aiming at partial pressures of carbon dioxide of 30 and 50 mmHg. Endpoints were CBF, blood flow velocity in the middle cerebral artery, and cerebral metabolic rates for oxygen, glucose, and lactate. Global CBF was measured using a modified Kety-Schmidt technique with argon as inert gas tracer. CBF velocity of the middle cerebral artery was recorded by transcranial Doppler sonography. Data were presented as mean (SD). Two-sided paired t tests and one-way ANOVA for repeated measures were used for statistical analysis. Moderate hyperventilation significantly decreased CBF by 60%, blood flow velocity by 41%, cerebral oxygen delivery by 58%, and partial pressure of oxygen of the jugular venous bulb by 45%. Cerebral metabolic rates for oxygen and glucose remained unchanged; however, net cerebral lactate efflux significantly increased from -0.38 (2.18) to -2.41(2.43) µmol min 100 g. Moderate hyperventilation, when compared with moderate hypoventilation, in patients with cardiovascular disease undergoing intravenous anesthesia increased net cerebral lactate efflux and markedly reduced CBF and partial pressure of oxygen of the jugular venous bulb, suggesting partial impairment of cerebral aerobic metabolism at clinically relevant levels of hypocapnia.

  4. Bronchodilator efficacy of extrafine glycopyrronium bromide: the Glyco 2 study

    Directory of Open Access Journals (Sweden)

    Singh D

    2017-07-01

    Full Text Available Dave Singh,1 Mario Scuri,2 Sara Collarini,2 Stefano Vezzoli,2 Fabrizia Mariotti,2 Annamaria Muraro,2 Daniela Acerbi2 1Medicines Evaluation, University Of Manchester, University Hospital of South Manchester, Manchester, UK; 2Global Clinical Development, Chiesi Farmaceutici SpA, Parma, Italy Abstract: An extrafine formulation of the long-acting muscarinic antagonist glycopyrronium bromide (GB is in development for chronic obstructive pulmonary disease (COPD, in combination with beclometasone dipropionate and formoterol fumarate – a “fixed triple”. This two-part study was randomized, double blind, placebo controlled in patients with moderate-to-severe COPD: Part 1: single-dose escalation, GB 12.5, 25, 50, 100 or 200 µg versus placebo; Part 2: repeat-dose (7-day, four-period crossover, GB 12.5, 25 or 50 µg twice daily (BID versus placebo, with an open-label extension in which all patients received tiotropium 18 µg once daily. On the morning of Day 8 in all five periods, patients also received formoterol 12 µg. In study Part 1, 27 patients were recruited. All GB doses significantly increased from baseline forced expiratory volume in 1 second (FEV1 area under the curve (AUC0–12h and peak FEV1, with a trend toward greater efficacy with higher GB dose. All adverse events were mild–moderate in severity, with a lower incidence with GB than placebo and no evidence of a dose–response relationship. In study Part 2, of 38 patients recruited, 34 completed the study. Adjusted mean differences from placebo in 12 h trough FEV1 on Day 7 (primary were 115, 142 and 136 mL for GB 12.5, 25 and 50 µg BID, respectively (all P<0.001. GB 25 and 50 µg BID were superior (P<0.05 to GB 12.5 µg BID for pre-dose morning FEV1 on Day 8. For this endpoint, GB 25 and 50 µg BID were also superior to tiotropium. Compared with Day 7, addition of formoterol significantly increased Day 8 FEV1 peak and AUC0–12h with all GB doses and placebo (all P<0.001. All

  5. SYNTHESIS AND ANTIPLASMODIAL ACTIVITY TESTING OF (1-N-(4-METHOXYBENZYL-1,10-PHENANTHROLINIUM BROMIDE

    Directory of Open Access Journals (Sweden)

    Ruslin Hadanu

    2010-06-01

    Full Text Available Synthesis of (1-N-(4-methoxybenzyl-1,10-phenanthroline bromide from 1,10-phenanthroline monohydrate and 4-methoxybenzaldehyde as starting material and evaluation of its antiplasmodial activities have been carried out. The 4-methoxybenzyl alcohol was prepared from 4-methoxy-benzaldehyde using sodium borohydride (NaBH4 reagent and ethanol absolute solution. The mixture was refluxed for 3 h. To yield colorless dilution compound with 90.41 % in efficiency. Furthermore, bromination of 4-methoxybenzyl alcohol with phosphorus bromide (PBr3 was conducted by refluxing for 3 h. The product of this reaction was yellow liquid of 4-methoxybenzyl bromide, 79.03% yield and 95.34 % purity. The final step of reaction was benzylation of 1,10-phenanthroline monohydrate with 4-methoxybenzyl bromide reagent. It was conducted by refluxing in aceton for 8 h at 55 oC. The yield of the reaction was (1-N-(4-methoxybenzyl-1,10-phenanthroline bromide (77.63%. It is pink solid form, and its melting point is 192-193 oC. Identification of the product was carried out by means of GC-MS, IR and 1H-NMR spectrometers. The in vitro antiplasmodial activity on chloroquine-resistant Plasmodium falciparum FCR-3 strain and chloroquine sensitive P. falciparum D10 strain for (1-N-(4-methoxybenzyl-1,10-phenanthroline bromide were determined by microscopic method. The result showed that after 72 h incubation, it has IC50 0.93±0.02 µM and 1.21±0.09 µM, respectively.   Keywords: 1,10-phenanthroline,  (1-N-(4-methoxybenzyl-1,10-phenanthroline bromide, 4 methoxybenzaldehyde, antiplasmodial activities

  6. Dynamics of temperature normalized stem CO2 efflux in Norway spruce stand

    Directory of Open Access Journals (Sweden)

    Eva Dařenová

    2011-01-01

    Full Text Available Respiration of stems contributes approximately 8 to 13 % to the total respiration of forest ecosystem, which is not negligible, and it has to be included in carbon flux estimates. The aim of this study was to determine dynamics of stem CO2 efflux during the growing season in Norway spruce stand and factors affecting this efflux. Continuous measurements of stem CO2 efflux were carried out by an automated system during the growing season in 2006–2009. Further measured characteristics were stem temperature, stem increment and precipitations. Stem CO2 efflux was in tight relationship with changes in temperature with the mean coefficient of determination of 0.76. This infers that temperature was the main factor driving changes in CO2 efflux during the season. To eliminate effect of temperature and determine other factors influencing stem CO2 efflux, CO2 efflux was normalized for temperature of 10 °C (R10. Basic seasonal course of R10 followed the pattern of stem growth rate with its maxima in June and July. The other factor effect, which was possible to determine, was presence of rainfall. Rainfall strong enough caused mostly increase in R10. This effect was the most significant when the R10 course had a decreasing trend in the second part of the growing season.

  7. Inside out: efflux of carbon dioxide from leaves represents more than leaf metabolism.

    Science.gov (United States)

    Stutz, Samantha S; Anderson, Jeremiah; Zulick, Rachael; Hanson, David T

    2017-05-17

    High concentrations of inorganic carbon in the xylem, produced from root, stem, and branch respiration, travel via the transpiration stream and eventually exit the plant through distant tissues as CO2. Unlike previous studies that focused on the efflux of CO2 from roots and woody tissues, we focus on efflux from leaves and the potential effect on leaf respiration measurements. We labeled transported inorganic carbon, spanning reported xylem concentrations, with 13C and then manipulated transpiration rates in the dark in order to vary the rates of inorganic carbon supply to cut leaves from Brassica napus and Populus deltoides. We used tunable diode laser absorbance spectroscopy to directly measure the rate of gross 13CO2 efflux, derived from inorganic carbon supplied from outside of the leaf, relative to gross 12CO2 efflux generated from leaf cells. These experiemnts showed that 13CO2 efflux was dependent upon the rate of inorganic carbon supply to the leaf and the rate of transpiration. Our data show that the gross leaf efflux of xylem-transported CO2 is likely small in the dark when rates of transpiration are low. However, gross leaf efflux of xylem-transported CO2 could approach half the rate of leaf respiration in the light when transpiration rates and branch inorganic carbon concentrations are high, irrespective of the grossly different petiole morphologies in our experiment. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  8. Interplay between Three RND Efflux Pumps in Doxycycline-Selected Strains of Burkholderia thailandensis

    Science.gov (United States)

    Biot, Fabrice Vincent; Lopez, Mélanie Monique; Poyot, Thomas; Neulat-Ripoll, Fabienne; Lignon, Sabrina; Caclard, Arnaud; Thibault, François Michel; Peinnequin, Andre; Pagès, Jean-Marie; Valade, Eric

    2013-01-01

    Background Efflux systems are involved in multidrug resistance in most Gram-negative non-fermentative bacteria. We have chosen Burkholderia thailandensis to dissect the development of multidrug resistance phenotypes under antibiotic pressure. Methodology/Principal Findings We used doxycycline selection to obtain several resistant B. thailandensis variants. The minimal inhibitory concentrations of a large panel of structurally unrelated antibiotics were determined ± the efflux pump inhibitor phenylalanine-arginine ß-naphthylamide (PAßN). Membrane proteins were identified by proteomic method and the expressions of major efflux pumps in the doxycycline selected variants were compared to those of the parental strains by a quantitative RT-PCR analysis. Doxycycline selected variants showed a multidrug resistance in two major levels corresponding to the overproduction of two efflux pumps depending on its concentration: AmrAB-OprA and BpeEF-OprC. The study of two mutants, each lacking one of these pumps, indicated that a third pump, BpeAB-OprB, could substitute for the defective pump. Surprisingly, we observed antagonistic effects between PAßN and aminoglycosides or some ß-lactams. PAßN induced the overexpression of AmrAB-OprA and BpeAB-OprB pump genes, generating this unexpected effect. Conclusions/Significance These results may account for the weak activity of PAßN in some Gram-negative species. We clearly demonstrated two antagonistic effects of this molecule on bacterial cells: the blocking of antibiotic efflux and an increase in efflux pump gene expression. Thus, doxycycline is a very efficient RND efflux pump inducer and PAßN may promote the production of some efflux pumps. These results should be taken into account when considering antibiotic treatments and in future studies on efflux pump inhibitors. PMID:24386333

  9. Association of Cholesterol Efflux Capacity With Clinical Features of Metabolic Syndrome: Relevance to Atherosclerosis.

    Science.gov (United States)

    Gall, Julie; Frisdal, Eric; Bittar, Randa; Le Goff, Wilfried; Bruckert, Eric; Lesnik, Philippe; Guerin, Maryse; Giral, Philippe

    2016-11-23

    The contribution of high-density lipoprotein to cardiovascular benefit is closely linked to its role in the cellular cholesterol efflux process; however, various clinical and biochemical variables are known to modulate the overall cholesterol efflux process. The aim of this study was to evaluate the extent to which clinical and biological anomalies associated with the establishment of the metabolic syndrome modulate cholesterol efflux capacity and contribute to development of atherosclerosis. This study involved patients (n=1202) displaying atherogenic dyslipidemia in primary prevention who were referred to our prevention center. Among these patients, 25% presented at least 3 criteria of the metabolic syndrome, as defined by the National Cholesterol Education Program Adult Treatment Panel III. We measured the capacity of 40-fold diluted serum to mediate cholesterol efflux from cholesterol-loaded human THP-1 macrophages. Cholesterol efflux capacity was reduced progressively by 4% to 11% (Pmetabolic syndrome from 1 to 5. This observation was primarily related to reductions in scavenger receptor class B member 1 and ATP binding cassette subfamily G member 1-dependent efflux. Multivariate analyses indicate that serum efflux capacity was significantly associated with established metabolic syndrome (odds ratio 0.45; 95% CI 0.28-0.72; P=0.009) independent of age, low-density lipoprotein cholesterol, status with regard to lipid-lowering therapy, smoking status, and alcohol consumption. Our study revealed that individual criteria of metabolic syndrome are closely related synergistically to cholesterol efflux capacity. In addition, established metabolic syndrome and cholesterol efflux capacity were independently associated with clinical features of atherosclerosis. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  10. Temporal dynamics of soil CO2 efflux in the Northern Pantanal of Mato Grosso, Brazil

    Science.gov (United States)

    Pinto-Jr, O. B.; Brandão, A. A.; Lathuilliere, M. J.; Dalmagro, H. J.; Arruda, P. H.; Couto, E. G.; Johnson, M. S.

    2013-12-01

    To answer questions about the role of different ecosystems, especially wetlands, the carbon cycle, it is necessary to monitor the vertical fluxes of CO2, soil respiration, and all other parameters that can be correlated with them, so to quantify them and relate them. In this context we measured the soil CO2 efflux of a tree island (locally known as a cordilheira) in the Northern Pantanal, near Poconé, Mato Grosso and verified the influence of environmental parameters on the measurements. We also modeled values of Q10 (parameter used to characterize the dependence of the efflux of CO2 from the soil with the soil temperature) as a function of soil temperature and ground CO2 efflux a); as a comparison to our CO2 efflux measurements. The average soil CO2 efflux was 3.98×1.69 μmolm-2s-1. Soil temperature and O2 content significantly influenced CO2 efflux during inundation periods, high water and ebb, while soil moisture and soil CO2 concentration significantly influenced the CO2 efflux during periods of ebb and drought. The matric potential at 10 cm depth significantly influenced the CO2 efflux throughout the measurement period. The average value of the Q10 was 2.16, and did not differ statistically from the modeled Q10. The average value of the soil CO2 efflux estimated was 4.07×0.84 μmolm-2s-1, and was statistically similar to the average value measured.

  11. The (95)(Δ)G mutation in the 5'untranslated region of the norA gene increases efflux activity in Staphylococcus epidermidis isolates.

    Science.gov (United States)

    García-Gómez, Elizabeth; Jaso-Vera, Marcos E; Juárez-Verdayes, Marco A; Alcántar-Curiel, María D; Zenteno, Juan C; Betanzos-Cabrera, Gabriel; Peralta, Humberto; Rodríguez-Martínez, Sandra; Cancino-Díaz, Mario E; Jan-Roblero, Janet; Cancino-Diaz, Juan C

    2017-02-01

    In the Staphylococcus aureus ATCC25923 strain, the flqB mutation in the 5'untranslated region (5'UTR) of the norA gene causes increased norA mRNA expression and high efflux activity (HEA). The involvement of the norA gene 5'UTR in HEA has not been explored in S. epidermidis; therefore, we examined the function of this region in S. epidermidis clinical isolates. The selection of isolates with HEA was performed based on ethidium bromide (EtBr) MIC values and efflux efficiency (EF) using the semi-automated fluorometric method. The function of the 5'UTR was studied by quantifying the levels of norA expression (RT-qPCR) and by identifying 5'UTR mutations by sequence analysis. Only 10 isolates from a total of 165 (6.1%) had HEA (EtBr MIC = 300 μg/ml and EF ranged from 48.4 to 97.2%). Eight of 10 isolates with HEA had the 5'UTR (95)(Δ)G mutation. Isolates carrying the (95)(Δ)G mutation had higher levels of norA expression compared with those that did not. To corroborate that the (95)(Δ)G mutation is involved in HEA, a strain adapted to EtBr was obtained in vitro. This strain also presented the (95)(Δ)G mutation and had a high level of norA expression and EF, indicating that the (95)(Δ)G mutation is important for the HEA phenotype. The (95)(Δ)G mutation produces a different structure in the Shine-Dalgarno region, which may promote better translation of norA mRNA. To our knowledge, this is the first report to demonstrate the participation of the 5'UTR (95)(Δ)G mutation of the norA gene in the HEA phenotype of S. epidermidis isolates. Here, we propose that the efflux of EtBr is caused by an increment in the transcription and/or translation of the norA gene. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Modulation of Bacterial Multidrug Resistance Efflux Pumps of the Major Facilitator Superfamily

    Directory of Open Access Journals (Sweden)

    Sanath Kumar

    2013-01-01

    Full Text Available Bacterial infections pose a serious public health concern, especially when an infectious disease has a multidrug resistant causative agent. Such multidrug resistant bacteria can compromise the clinical utility of major chemotherapeutic antimicrobial agents. Drug and multidrug resistant bacteria harbor several distinct molecular mechanisms for resistance. Bacterial antimicrobial agent efflux pumps represent a major mechanism of clinical resistance. The major facilitator superfamily (MFS is one of the largest groups of solute transporters to date and includes a significant number of bacterial drug and multidrug efflux pumps. We review recent work on the modulation of multidrug efflux pumps, paying special attention to those transporters belonging primarily to the MFS.

  13. Utility of bromide and heat tracers for aquifer characterization affected by highly transient flow conditions

    Science.gov (United States)

    Ma, Rui; Zheng, Chunmiao; Zachara, John M.; Tonkin, Matthew

    2012-08-01

    A tracer test using both bromide and heat tracers conducted at the Integrated Field Research Challenge site in Hanford 300 Area (300A), Washington, provided an instrument for evaluating the utility of bromide and heat tracers for aquifer characterization. The bromide tracer data were critical to improving the calibration of the flow model complicated by the highly dynamic nature of the flow field. However, most bromide concentrations were obtained from fully screened observation wells, lacking depth-specific resolution for vertical characterization. On the other hand, depth-specific temperature data were relatively simple and inexpensive to acquire. However, temperature-driven fluid density effects influenced heat plume movement. Moreover, the temperature data contained "noise" caused by heating during fluid injection and sampling events. Using the hydraulic conductivity distribution obtained from the calibration of the bromide transport model, the temperature depth profiles and arrival times of temperature peaks simulated by the heat transport model were in reasonable agreement with observations. This suggested that heat can be used as a cost-effective proxy for solute tracers for calibration of the hydraulic conductivity distribution, especially in the vertical direction. However, a heat tracer test must be carefully designed and executed to minimize fluid density effects and sources of noise in temperature data. A sensitivity analysis also revealed that heat transport was most sensitive to hydraulic conductivity and porosity, less sensitive to thermal distribution factor, and least sensitive to thermal dispersion and heat conduction. This indicated that the hydraulic conductivity remains the primary calibration parameter for heat transport.

  14. Redox enhanced energy storage in an aqueous high-voltage electrochemical capacitor with a potassium bromide electrolyte

    Science.gov (United States)

    Li, Qi; Haque, Mazharul; Kuzmenko, Volodymyr; Ramani, Namrata; Lundgren, Per; Smith, Anderson D.; Enoksson, Peter

    2017-04-01

    This paper reports a detailed electrochemical investigation of a symmetric carbon-carbon electrochemical device with a potassium bromide (KBr) electrolyte. Below 1.6 V, KBr gives electrochemical double layer behavior. At higher voltages the Br- / Br3- redox reaction comes into effect and enhances the energy storage. The redox-enhanced device has a high energy density, excellent stability, as well as high coulombic and energy efficiencies even at 1.9 V. More importantly, the redox contribution can be ;triggered; by pre-cycling at 1.9 V, and remains beneficial after switching to 1.6 V. The triggering operation leads to a 22% increase in stored energy with negligible sacrifice of power. The intriguing behavior is accompanied by a series of complex variations including the shifts of electrode potential limits and the shift of potential of zero voltage. The electro-oxidation of the positive electrode and kinetics of the Br- /Br3- electrode reactions are proposed to be the main causes for the triggering phenomenon. These findings provide means to improve the design and operation of devices that contain bromine, or other redox species with a comparably high electrode potential.

  15. 78 FR 14508 - Notice of Affirmation of Addition of a Treatment Schedule for Methyl Bromide Fumigation of...

    Science.gov (United States)

    2013-03-06

    ... methyl bromide fumigation of cottonseed for the fungal plant pathogen Fusarium oxysporum f. sp... schedule to neutralize the fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV) on cottonseed...

  16. Methyl bromide: ocean sources, ocean sinks, and climate sensitivity.

    Science.gov (United States)

    Anbar, A D; Yung, Y L; Chavez, F P

    1996-03-01

    The oceans play an important role in the geochemical cycle of methyl bromide (CH3Br), the major carrier of O3-destroying bromine to the stratosphere. The quantity of CH3Br produced annually in seawater is comparable to the amount entering the atmosphere each year from natural and anthropogenic sources. The production mechanism is unknown but may be biological. Most of this CH3Br is consumed in situ by hydrolysis or reaction with chloride. The size of the fraction which escapes to the atmosphere is poorly constrained; measurements in seawater and the atmosphere have been used to justify both a large oceanic CH3Br flux to the atmosphere and a small net ocean sink. Since the consumption reactions are extremely temperature-sensitive, small temperature variations have large effects on the CH3Br concentration in seawater, and therefore on the exchange between the atmosphere and the ocean. The net CH3Br flux is also sensitive to variations in the rate of CH3Br production. We have quantified these effects using a simple steady state mass balance model. When CH3Br production rates are linearly scaled with seawater chlorophyll content, this model reproduces the latitudinal variations in marine CH3Br concentrations observed in the east Pacific Ocean by Singh et al. [1983] and by Lobert et al. [1995]. The apparent correlation of CH3Br production with primary production explains the discrepancies between the two observational studies, strengthening recent suggestions that the open ocean is a small net sink for atmospheric CH3Br, rather than a large net source. The Southern Ocean is implicated as a possible large net source of CH3Br to the atmosphere. Since our model indicates that both the direction and magnitude of CH3Br exchange between the atmosphere and ocean are extremely sensitive to temperature and marine productivity, and since the rate of CH3Br production in the oceans is comparable to the rate at which this compound is introduced to the atmosphere, even small

  17. Characterization of micelle formation of dodecyldimethyl-N-2-phenoxyethylammonium bromide in aqueous solution.

    Science.gov (United States)

    Khatua, Dibyendu; Gupta, Abhisek; Dey, Joykrishna

    2006-06-01

    Aggregation behavior of dodecyldimethyl-N-2-phenoxyethylammonium bromide commonly called domiphen bromide (DB) was studied in aqueous solution. The Krafft temperature of the surfactant was measured. The surfactant has been shown to form micellar structures in a wide concentration range. The critical micelle concentration was determined by surface tension, conductivity, and fluorescence methods. The conductivity data were also employed to determine the degree of surfactant counterion dissociation. The changes in Gibb's free energy, enthalpy, and entropy of the micellization process were determined at different temperature. The steady-state fluorescence quenching measurements with pyrene and N-phenyl-1-naphthylamine as fluorescence probes were performed to obtain micellar aggregation number. The results were compared with those of dodecyltrimethylammonium bromide (DTAB) surfactant. The micelle formation is energetically more favored in DB compared to that in DTAB. The 1H-NMR spectra were used to show that the 2-phenoxyethyl group, which folds back onto the micellar surface facilitates aggregate formation in DB.

  18. Corrosion Behavior of Austenitic and Duplex Stainless Steels in Lithium Bromide

    Directory of Open Access Journals (Sweden)

    Ayo Samuel AFOLABI

    2009-07-01

    Full Text Available The corrosion behavior of austenitic and duplex stainless steels in various concentrations of lithium, bromide solution was investigated by using the conventional weight loss measurement method. The results obtained show that corrosion of these steels occurred due to the aggressive bromide ion in the medium. Duplex stainless steel shows a greater resistance to corrosion than austenitic stainless steel in the medium. This was attributed to equal volume proportion of ferrite and austenite in the structure of duplex stainless steel coupled with higher content of chromium in its composition. Both steels produced electrochemical noise at increased concentrations of lithium bromide due to continuous film breakdown and repair caused by reduction in medium concentration by the alkaline corrosion product while surface passivity observed in duplex stainless steel is attributed to film stability on this steel.

  19. Alternatives to methyl bromide treatments for stored-product and quarantine insects.

    Science.gov (United States)

    Fields, Paul G; White, Noel D G

    2002-01-01

    Methyl bromide is used to control insects as a space fumigant in flour and feed mills and ship holds, as a product fumigant for some fruit and cereals, and for general quarantine purposes. Methyl bromide acts rapidly, controlling insects in less than 48 h in space fumigations, and it has a wide spectrum of activity, controlling not only insects but also nematodes and plant-pathogenic microbes. This chemical will be banned in 2005 in developed countries, except for exceptional quarantine purposes, because it depletes ozone in the atmosphere. Many alternatives have been tested as replacements for methyl bromide, from physical control methods such as heat, cold, and sanitation to fumigant replacements such as phosphine, sulfuryl fluoride, and carbonyl sulfide, among others. Individual situations will require their own type of pest control techniques, but the most promising include integrated pest management tactics and combinations of treatments such as phosphine, carbon dioxide, and heat.

  20. Crystal structure of the Neisseria gonorrhoeae MtrD inner membrane multidrug efflux pump.

    Directory of Open Access Journals (Sweden)

    Jani Reddy Bolla

    Full Text Available Neisseria gonorrhoeae is an obligate human pathogen and the causative agent of the sexually-transmitted disease gonorrhea. The control of this disease has been compromised by the increasing proportion of infections due to antibiotic-resistant strains, which are growing at an alarming rate. The MtrCDE tripartite multidrug efflux pump, belonging to the hydrophobic and amphiphilic efflux resistance-nodulation-cell division (HAE-RND family, spans both the inner and outer membranes of N. gonorrhoeae and confers resistance to a variety of antibiotics and toxic compounds. We here report the crystal structure of the inner membrane MtrD multidrug efflux pump, which reveals a novel structural feature that is not found in other RND efflux pumps.

  1. Soil carbon dioxide (CO2) efflux of two shrubs in response to plant ...

    African Journals Online (AJOL)

    Jane

    2010-10-11

    , Institute of Soil and Water ... Although plant density should affect soil carbon dioxide (CO2) efflux and carbon cycling in semi-arid regions, the effects ...... root and microbial contributions to soil respiration in Leymus chinensis ...

  2. Soil carbon effluxes in ecosystems of Forsmark and Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern (Dept. of Physical Geography and Ecosystem Analysis, Lund Univ. (Sweden))

    2007-12-15

    Soil carbon effluxes were estimated in a number of ecosystems in Laxemar and Forsmark investigations areas. It was done in a young Scots pine (Pinus sylvestris) stand, a wet deciduous stand, a poor fen and an agricultural field in the Laxemar investigation area in south-eastern Sweden (57 deg 5 min N, 16 deg 7 min E) and in a pasture, two Norway spruce (Picea abies) stands, a deciduous forest, a mire, a wet deciduous forest and a clear-cut in the Forsmark investigation area (60 deg 4 min N, 18 deg 2 min E). It was measured with the closed chamber technique in 2005 and 2006. Soil temperature at 10 cm depth, air temperature and photosynthetically active radiation (PAR) were also measured. Exponential regressions with soil respiration against air and soil temperature were used to estimate annual soil respiration. A hyperbolic curve with Gross Primary Production (GPP) against PAR was used for modelling GPP for the growing season in the poor fen and the agricultural area of Laxemar. The exponential regressions with soil respiration against air and soil temperature explained on average 33.6% and 44.0% of the variation, respectively. GPP of the ground vegetation were reducing soil carbon effluxes, in all stands but one of the spruce stands, the deciduous forest, the mire and the wet deciduous forest of Forsmark. The significant (all but spruce 2 in Forsmark) curves with GPP against PAR explained on average 22.7% of the variation in GPP. The cubic regressions with GPP against air temperature were only significant for the poor fen and the agricultural field in Laxemar and it explained on average 34.8% of the variation in GPP for these ecosystems. The exponential regressions with air and soil temperature against soil respiration could be used to temporally extrapolate the occasional field measurements. The hyperbolic curve with GPP against PAR could also be used for temporal extrapolation of GPP for the ecosystems without a tree layer, i.e. the poor fen and the agricultural

  3. Impact of repeated dry-wet cycles on soil CO2 efflux in a beech forest

    Science.gov (United States)

    Leitner, Sonja; Saronjic, Nermina; Kobler, Johannes; Holtermann, Christian; Zechmeister-Boltenstern, Sophie; Zimmermann, Michael

    2015-04-01

    Climate change research predicts that both frequency and intensity of weather extremes such as severe droughts and heavy rainfall events will increase in mid Europe over the next decades. Because soil moisture is one of the major factors controlling microbially-driven soil processes, a changed moisture regime will impact soil organic matter (SOM) decomposition and nutrient cycling. This in turn can lead to feedback effects between altered precipitation and changed soil CO2 fluxes which can intensify climate change. Soil microorganisms can go into a state of dormancy or form inactive cysts to protect themselves from osmotic stress during soil drying. However, severe droughts increase microbial mortality which slows down SOM decomposition and decreases soil CO2 efflux. The rewetting of dry soil, on the other hand, causes large CO2 emissions, which is also known as the "Birch effect". Until today it is not clear whether these CO2 peaks outweigh the drought-induced decrease of total CO2 efflux. To investigate the impact of repeated dry-wet cycles on soil CO2 efflux we are conducting a precipitation manipulation experiment in a temperate Austrian beech forest. Roofs exclude rainfall and simulate drought periods, and heavy rainfall events are simulated with a sprinkler system. We apply repeated dry-wet cycles in two intensities: one treatment receives 6 cycles of 1 month drought followed by 75mm irrigation, and a parallel treatment receives 3 cycles of 2 months drought followed by 150mm irrigation. Soil CO2 efflux is constantly monitored with an automated flux chamber system, and environmental parameters are recorded via dataloggers. Our results show that droughts significantly reduce soil CO2 effluxes, and that the reductions depend on the length of the drought periods, with longer droughts leading to stronger reductions of CO2 effluxes. In the first 24 to 48h after rewetting, CO2 emissions strongly increased, and then slowly decreased again. Soil CO2 efflux was

  4. Kinetics of human sperm acrosomal exocytosis.

    Science.gov (United States)

    Sosa, C M; Pavarotti, M A; Zanetti, M N; Zoppino, F C M; De Blas, G A; Mayorga, L S

    2015-03-01

    The acrosome reaction is a unique event in the lifespan of sperm characterized by the exocytosis of the acrosomal content and the release of hybrid vesicles formed by patches of the outer acrosomal membrane and the plasma membrane. This unique regulated exocytosis is mediated by essentially the same membrane fusion machinery present in neuroendocrine cells. However, whereas secretion in neuroendocrine cells occurs in less than a second, the acrosome reaction is normally assessed after several minutes of incubation with inducers. In this report, we measured the kinetics of human sperm exocytosis triggered by two stimuli (calcium ionophore and progesterone) by using electron microscopy and three different approaches based on the incorporation of fluorescent Pisum sativum agglutinin into the acrosome upon opening of fusion pores connecting the extracellular medium with the acrosomal lumen. The results with the different methods are consistent with a slow kinetics (t½ = 14 min). We also manipulated the system to measure different steps of the process. We observed that cytosolic calcium increased with a relatively fast kinetics (t½ = 0.1 min). In contrast, the swelling of the acrosomal granule that precedes exocytosis was a slow process (t½ = 13 min). When swelling was completed, the fusion pore opening was fast (t½ = 0.2 min). The results indicate that acrosomal swelling is the slowest step and it determines the kinetics of the acrosome reaction. After the swelling is completed, the efflux of calcium from intracellular stores triggers fusion pores opening and the release of hybrid vesicles in seconds. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Pregabalin as an adjunct to phenobarbital, potassium bromide, or a combination of phenobarbital and potassium bromide for treatment of dogs with suspected idiopathic epilepsy.

    Science.gov (United States)

    Dewey, Curtis W; Cerda-Gonzalez, Sofia; Levine, Jonathan M; Badgley, Britton L; Ducoté, Julie M; Silver, Gena M; Cooper, Jocelyn J; Packer, Rebecca A; Lavely, James A

    2009-12-15

    To assess tolerability and short-term efficacy of oral administration of pregabalin as an adjunct to phenobarbital, potassium bromide, or a combination of phenobarbital and potassium bromide for treatment of dogs with poorly controlled suspected idiopathic epilepsy. Open-label, noncomparative clinical trial. 11 client-owned dogs suspected of having idiopathic epilepsy that was inadequately controlled with phenobarbital, potassium bromide, or a combination of these 2 drugs. Dogs were treated with pregabalin (3 to 4 mg/kg [1.4 to 1.8 mg/lb], PO, q 8 h) for 3 months. Number of generalized seizures in the 3 months before and after initiation of pregabalin treatment was recorded. Number of responders (>or= 50% reduction in seizure frequency) was recorded, and seizure frequency before and after initiation of pregabalin treatment was compared by use of a nonparametric Wilcoxon signed rank test. Seizures were significantly reduced (mean, 57%; median, 50%) after pregabalin administration in the 9 dogs that completed the study; 7 were considered responders with mean and median seizure reductions of 64% and 58%, respectively. Adverse effects for pregabalin were reported in 10 dogs. Mean and median plasma pregabalin concentrations for all dogs were 6.4 and 7.3 microg/mL, respectively. Pregabalin may hold promise as a safe and effective adjunct anticonvulsant drug for epileptic dogs poorly controlled with the standard drugs phenobarbital or potassium bromide. Adverse effects of pregabalin appeared to be mild. Additional studies with larger numbers of dogs and longer follow-up intervals are warranted.

  6. Burkholderia pseudomallei resistance to antibiotics in biofilm-induced conditions is related to efflux pumps.

    Science.gov (United States)

    Sirijant, Nopphasul; Sermswan, Rasana W; Wongratanacheewin, Surasakdi

    2016-11-01

    Burkholderia pseudomallei, the causative agent of melioidosis, has been found to increase its resistance to antibiotics when growing as a biofilm. The resistance is related to several mechanisms. One of the possible mechanisms is the efflux pump. Using bioinformatics analysis, it was found that BPSL1661, BPSL1664 and BPSL1665 were orthologous genes of the efflux transporter encoding genes for biofilm-related antibiotic resistance, PA1874-PA1877 genes in Pseudomonas aeruginosa strain PAO1. Expression of selected encoding genes for the efflux transporter system during biofilm formation were investigated. Real-time reverse transcriptase PCR expression of amrB, cytoplasmic membrane protein of AmrAB-OprA efflux transporter encoding gene, was slightly increased, while BPSL1665 was significantly increased during growth of bacteria in biofilm formation. Minimum biofilm inhibition concentration and minimum biofilm eradication concentration (MBEC) of ceftazidime (CTZ), doxycycline (DOX) and imipenem were found to be 2- to 1024-times increased when compared to their MICs for of planktonic cells. Inhibition of the efflux transporter by adding phenylalanine arginine β-napthylamide (PAβN), a universal efflux inhibitor, decreased 2 to 16 times as much as MBEC in B. pseudomallei biofilms with CTZ and DOX. When the intracellular accumulation of antibiotics was tested to reveal the pump inhibition, only the concentrations of CTZ and DOX increased in PAβN treated biofilm. Taken together, these results indicated that BPSL1665, a putative precursor of the efflux pump gene, might be related to the adaptation of B. pseudomallei in biofilm conditions. Inhibition of efflux pumps may lead to a decrease of resistance to CTZ and DOX in biofilm cells.

  7. A multisite analysis of temporal random errors in soil CO2 efflux

    Science.gov (United States)

    Cueva, Alejandro; Bahn, Michael; Litvak, Marcy; Pumpanen, Jukka; Vargas, Rodrigo

    2015-04-01

    An important component of the terrestrial carbon balance is the efflux of CO2 from soils to the atmosphere, which is strongly influenced by changes in soil moisture and temperature. Continuous measurements of soil CO2 efflux are available around the world, and there is a need to develop and improve analyses to better quantify the precision of the measurements. We focused on random errors in measurements, which are caused by unknown and unpredictable changes such as fluctuating environmental conditions. We used the CO2 gradient flux method with two different algorithms to study the temporal variation of soil CO2 efflux and associated random errors at four different ecosystems with wide ranges in mean annual temperature, soil moisture, and soil CO2 efflux. Our results show that random errors were better explained by a double-exponential distribution, had a mean value close to zero, were nonheteroscedastic, and were independent of soil moisture conditions. Random errors increased with the magnitude of soil CO2 efflux and scale isometrically (scaling exponent ≈ 1) within and across all sites, with a single relation common to all data. This isometric scaling is unaffected by ecosystem type, soil moisture conditions, and soil CO2 efflux range (maximum and minimum values within an ecosystem). These results suggest larger uncertainty under extreme events that increase soil CO2 efflux rates. The accumulated annual uncertainty due to random errors varied between ±0.38 and ±2.39%. These results provide insights on the scalability of the sensitivity of soil CO2 efflux to changing weather conditions across ecosystems.

  8. Paradoxical Association of Enhanced Cholesterol Efflux With Increased Incident Cardiovascular Risks

    Science.gov (United States)

    Li, Xin-Min; Tang, Wai Hong Wilson; Mosior, Marian K.; Huang, Ying; Wu, Yuping; Matter, William; Gao, Vivian; Schmitt, David; DiDonato, Joseph A.; Fisher, Edward A.; Smith, Jonathan D.; Hazen, Stanley L.

    2013-01-01

    Objective Diminished cholesterol efflux activity of apolipoprotein B (apoB)–depleted serum is associated with prevalent coronary artery disease, but its prognostic value for incident cardiovascular events is unclear. We investigated the relationship of cholesterol efflux activity with both prevalent coronary artery disease and incident development of major adverse cardiovascular events (death, myocardial infarction, or stroke). Approach and Results Cholesterol efflux activity from free cholesterol–enriched macrophages was measured in 2 case– control cohorts: (1) an angiographic cohort (n=1150) comprising stable subjects undergoing elective diagnostic coronary angiography and (2) an outpatient cohort (n=577). Analysis of media from cholesterol efflux assays revealed that the high-density lipoprotein fraction (1.063cholesterol released, with the majority found within the lipoprotein particle–depleted fraction, where ≈60% was recovered after apolipoprotein A1 immunoprecipitation. Albumin immunoprecipitation recovered another ≈30% of radiolabeled cholesterol within this fraction. Enhanced cholesterol efflux activity from ATP-binding cassette transporter A1–stimulated macrophages was associated with reduced risk of prevalent coronary artery disease in unadjusted models within both cohorts; however, the inverse risk relationship remained significant after adjustment for traditional coronary artery disease risk factors only within the outpatient cohort. Surprisingly, higher cholesterol efflux activity was associated with increase in prospective (3 years) risk of myocardial infarction/stroke (adjusted hazard ratio, 2.19; 95% confidence interval, 1.02–4.74) and major adverse cardiovascular events (adjusted hazard ratio, 1.85; 95% confidence interval, 1.11–3.06). Conclusions Heightened cholesterol efflux to apoB-depleted serum was paradoxically associated with increased prospective risk for myocardial infarction, stroke, and death. The majority of released

  9. Directed evolution of an E. coli inner membrane transporter for improved efflux of biofuel molecules

    Science.gov (United States)

    2013-01-01

    Background The depletion of fossil fuels and the rising need to meet global energy demands have led to a growing interest in microbial biofuel synthesis, particularly in Escherichia coli, due to its tractable characteristics. Besides engineering more efficient metabolic pathways for synthesizing biofuels, efforts to improve production yield by engineering efflux systems to overcome toxicity problems is also crucial. This study aims to enhance hydrocarbon efflux capability in E. coli by engineering a native inner membrane transporter, AcrB, using the directed evolution approach. Results We developed a selection platform based on competitive growth using a toxic substrate surrogate, which allowed rapid selection of AcrB variants showing enhanced efflux of linear and cyclic fuel molecule candidates, n-octane and α-pinene. Two mutants exhibiting increased efflux efficiency for n-octane and α-pinene by up to 47% and 400%, respectively, were isolated. Single-site mutants based on the mutations found in the isolated variants were synthesized and the amino acid substitutions N189H, T678S, Q737L and M844L were identified to have conferred improvement in efflux efficiency. The locations of beneficial mutations in AcrB suggest their contributions in widening the substrate channel, altering the dynamics of substrate efflux and promoting the assembly of AcrB with the outer membrane channel protein TolC for more efficient substrate export. It is interesting to note that three of the four beneficial mutations were located relatively distant from the known substrate channels, thus exemplifying the advantage of directed evolution over rational design. Conclusions Using directed evolution, we have isolated AcrB mutants with improved efflux efficiency for n-octane and α-pinene. The utilization of such optimized native efflux pumps will increase productivity of biofuels synthesis and alleviate toxicity and difficulties in production scale-up in current microbial platforms. PMID

  10. The Heterodimeric ABC Transporter EfrCD Mediates Multidrug Efflux in Enterococcus faecalis

    Science.gov (United States)

    Hürlimann, Lea M.; Corradi, Valentina; Hohl, Michael; Bloemberg, Guido V.; Tieleman, D. Peter

    2016-01-01

    Nosocomial infections with Enterococcus faecalis are an emerging health problem. However, drug efflux pumps contributing to intrinsic drug resistance are poorly studied in this Gram-positive pathogen. In this study, we functionally investigated seven heterodimeric ABC transporters of E. faecalis that are annotated as drug efflux pumps. Deletion of ef0789-ef0790 on the chromosome of E. faecalis resulted in increased susceptibility to daunorubicin, doxorubicin, ethidium, and Hoechst 33342, and the corresponding transporter was named EfrCD. Unexpectedly, the previously described heterodimeric multidrug ABC transporter EfrAB contributes marginally to drug efflux in the endogenous context of E. faecalis. In contrast, heterologous expression in Lactococcus lactis revealed that EfrAB, EfrCD, and the product of ef2226-ef2227 (EfrEF) mediate the efflux of fluorescent substrates and confer resistance to multiple dyes and drugs, including fluoroquinolones. Four of seven transporters failed to exhibit drug efflux activity for the set of drugs and dyes tested, even upon overexpression in L. lactis. Since all seven transporters were purified as heterodimers after overexpression in L. lactis, a lack of drug efflux activity is not attributed to poor expression or protein aggregation. Reconstitution of the purified multidrug transporters EfrAB, EfrCD, and EfrEF in proteoliposomes revealed functional coupling between ATP hydrolysis and drug binding. Our analysis creates an experimental basis for the accurate prediction of drug efflux transporters and indicates that many annotated multidrug efflux pumps might be incapable of drug transport and thus might fulfill other physiological functions in the cell. PMID:27381387

  11. Well-Defined Copper(I) Fluoroalkoxide Complexes for Trifluoroethoxylation of Aryl and Heteroaryl Bromides

    KAUST Repository

    Huang, Ronglu

    2015-03-17

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Copper(I) fluoroalkoxide complexes bearing dinitrogen ligands were synthesized and the structure and reactivity of the complexes toward trifluoroethoxylation, pentafluoropropoxylation, and tetrafluoropropoxylation of aryl and heteroaryl bromides were investigated. Efficiency drive: A series of copper(I) fluoroalkoxide complexes bearing N,N ligands have been prepared and structurally characterized. These well-defined complexes serve as efficient reagents for the fluoroalkoxylation of aryl and heteroaryl bromides to produce a wide range of trifluoroethyl, pentafluoropropyl, and tetrafluoropropyl (hetero)aryl ethers in good to excellent yields.

  12. Bromide, Chloride, and Sulfate Concentrations, and Specific Conductance, Lake Texoma, Texas and Oklahoma, 2007-08

    Science.gov (United States)

    Baldys, Stanley

    2009-01-01

    The U.S. Geological Survey, in cooperation with the City of Dallas Water Utilities Division, collected water-quality data from 11 sites on Lake Texoma, a reservoir on the Texas-Oklahoma border, during April 2007-September 2008. At 10 of the sites, physical properties (depth, specific conductance, pH, temperature, dissolved oxygen, and alkalinity) were measured and samples were collected for analysis of selected dissolved constituents (bromide, calcium, magnesium, potassium, sodium, carbonate, bicarbonate, chloride, and sulfate); at one site, only physical properties were measured. The primary constituent of interest was bromide. Bromate can form when ozone is used to disinfect raw water containing bromide, and bromate is a suspected human carcinogen. Chloride and sulfate were of secondary interest. Only the analytical results for bromide, chloride, sulfate, and measured specific conductance are discussed in this report. Median dissolved bromide concentrations ranged from 0.28 to 0.60 milligrams per liter. The largest median dissolved bromide concentration (0.60 milligram per liter at site 11) was from the Red River arm of Lake Texoma. Dissolved bromide concentrations generally were larger in the Red River arm of Lake Texoma than in the Washita arm of the lake. Median dissolved chloride concentrations were largest in the Red River arm of Lake Texoma at site 11 (431 milligrams per liter) and smallest at site 8 (122 milligrams per liter) in the Washita arm. At site 11 in the Red River arm, the mean and median chloride concentrations exceeded the secondary maximum contaminant level of 300 milligrams per liter for chloride established by the 'Texas Surface Water Quality Standards' for surface-water bodies designated for the public water supply use. Median dissolved sulfate concentrations ranged from 182 milligrams per liter at site 4 in the Big Mineral arm to 246 milligrams per liter at site 11 in the Red River arm. None of the mean or median sulfate concentrations

  13. Lithium Bromide/Water as Additives in Dearomatizing Samarium-Ketyl (Hetero)Arene Cyclizations.

    Science.gov (United States)

    Rao, Chintada Nageswara; Bentz, Christoph; Reissig, Hans-Ulrich

    2015-11-02

    New conditions for dearomatizing samarium-ketyl (hetero)arene cyclizations are reported. In many examples of these samarium diiodide-mediated reactions, lithium bromide and water can be used as additives instead of the carcinogenic and mutagenic hexamethylphosphoramide (HMPA). The best results were obtained for the cyclizations of N-acylated indole derivatives delivering the expected indolines in good yields and excellent diastereoselectivities. A new type of cyclization delivering indolyl-substituted allene derivatives is also described. The scope and limitations of the lithium bromide/water system are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Lithium bromide-induced structural changes in a nickel bis-alkoxide complex.

    Science.gov (United States)

    Ichiokai, Hiromi; Vicic, David A

    2013-01-01

    The bis-alkoxide [(DEAMP)2Ni] (1, DEAMP = 1-(diethylamino)-2-methylpropan-2-olate) was found to react with trace amounts of lithium bromide to afford the bis-LiBr adduct 2, in which the oxygens of the DEAMP ligand coordinate to lithium to form a chiral-at-metal complex. This new complex is five-coordinate at nickel, and contains nickel and oxygen atoms which are all chiral. One diastereomer precipitates from pentane solution. The two lithium ions rigidify the new structure in the solid state by coordinating to the oxygen and bromide atoms.

  15. Valence photoelectron spectra of alkali bromides calculated within the propagator theory

    DEFF Research Database (Denmark)

    Karpenko, Alexander; Iablonskyi, Denys; Aksela, Helena

    2013-01-01

    The valence ionization spectra covering the binding energy range 0-45 eV of alkali bromide XBr (X = Li, Na, K, Rb) vapors are studied within the framework of the propagator theory. Relativistic Algebraic Diagrammatic Construction calculations have been carried out in order to investigate photoion......The valence ionization spectra covering the binding energy range 0-45 eV of alkali bromide XBr (X = Li, Na, K, Rb) vapors are studied within the framework of the propagator theory. Relativistic Algebraic Diagrammatic Construction calculations have been carried out in order to investigate...... photoionization processes and to describe molecular electronic structure. Theoretical results are compared with available experimental data....

  16. New Roads Leading to Old Destinations: Efflux Pumps as Targets to Reverse Multidrug Resistance in Bacteria

    Directory of Open Access Journals (Sweden)

    Gabriella Spengler

    2017-03-01

    Full Text Available Multidrug resistance (MDR has appeared in response to selective pressures resulting from the incorrect use of antibiotics and other antimicrobials. This inappropriate application and mismanagement of antibiotics have led to serious problems in the therapy of infectious diseases. Bacteria can develop resistance by various mechanisms and one of the most important factors resulting in MDR is efflux pump-mediated resistance. Because of the importance of the efflux-related multidrug resistance the development of new therapeutic approaches aiming to inhibit bacterial efflux pumps is a promising way to combat bacteria having over-expressed MDR efflux systems. The definition of an efflux pump inhibitor (EPI includes the ability to render the bacterium increasingly more sensitive to a given antibiotic or even reverse the multidrug resistant phenotype. In the recent years numerous EPIs have been developed, although so far their clinical application has not yet been achieved due to their in vivo toxicity and side effects. In this review, we aim to give a short overview of efflux mediated resistance in bacteria, EPI compounds of plant and synthetic origin, and the possible methods to investigate and screen EPI compounds in bacterial systems.

  17. Phytochemicals increase the antibacterial activity of antibiotics by acting on a drug efflux pump.

    Science.gov (United States)

    Ohene-Agyei, Thelma; Mowla, Rumana; Rahman, Taufiq; Venter, Henrietta

    2014-12-01

    Drug efflux pumps confer resistance upon bacteria to a wide range of antibiotics from various classes. The expression of efflux pumps are also implicated in virulence and biofilm formation. Moreover, organisms can only acquire resistance in the presence of active drug efflux pumps. Therefore, efflux pump inhibitors (EPIs) are attractive compounds to reverse multidrug resistance and to prevent the development of resistance in clinically relevant bacterial pathogens. We investigated the potential of pure compounds isolated from plants to act as EPIs. In silico screening was used to predict the bioactivity of plant compounds and to compare that with the known EPI, phe-arg-β-naphthylamide (PAβN). Subsequently, promising products have been tested for their ability to inhibit efflux. Plumbagin nordihydroguaretic acid (NDGA) and to a lesser degree shikonin, acted as sensitizers of drug-resistant bacteria to currently used antibiotics and were able to inhibit the efflux pump-mediated removal of substrate from cells. We demonstrated the feasibility of in silico screening to identify compounds that potentiate the action of antibiotics against drug-resistant strains and which might be potentially useful lead compounds for an EPI discovery program. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  18. An ex vivo study of nitric oxide efflux from human erythrocytes in both genders.

    Science.gov (United States)

    Duarte, Catarina; Napoleão, Patrícia; Freitas, Teresa; Saldanha, Carlota

    2016-01-01

    Acetylcholinesterase (AChE) is located on outer surface of erythrocyte membrane. Gender-related differences in erythrocyte AChE enzyme activity had been verified in young adults. It is also known that binding of acetylcholine (ACh) with AChE on erythrocyte membrane initiates a signal transduction mechanism that stimulates nitric oxide (NO) efflux. This ex vivo study was done to compare the amount of NO efflux obtained from erythrocytes of healthy donors in males and females. We included 66 gender age-matched healthy donors (40-60 years old). We performed quantification of erythrocyte NO efflux from erythrocytes and of the membrane AChE enzyme activity. There are no significant differences in NO efflux from erythrocytes between men and women. Regarding AChE enzyme activity values, in this range of age, no differences between genders were obtained. However, the values of AChE enzyme activity in the third quartile of NO efflux values were significantly higher (p gender. For the same range of values of NO efflux from erythrocytes, in both gender, it was verified higher values of AChE enzyme activity in women.

  19. The effect of N-acetylcysteine on chloride efflux from airway epithelial cells.

    Science.gov (United States)

    Varelogianni, Georgia; Oliynyk, Igor; Roomans, Godfried M; Johannesson, Marie

    2010-01-27

    Defective chloride transport in epithelial cells increases mucus viscosity and leads to recurrent infections with high oxidative stress in patients with CF (cystic fibrosis). NAC (N-acetylcysteine) is a well known mucolytic and antioxidant drug, and an indirect precursor of glutathione. Since GSNO (S-nitrosoglutathione) previously has been shown to be able to promote Cl- efflux from CF airway epithelial cells, it was investigated whether NAC also could stimulate Cl- efflux from CF and non-CF epithelial cells and through which mechanisms. CFBE (CF bronchial epithelial cells) and normal bronchial epithelial cells (16HBE) were treated with 1 mM, 5 mM, 10 mM or 15 mM NAC for 4 h at 37 degrees C. The effect of NAC on Cl- transport was measured by Cl- efflux measurements and by X-ray microanalysis. Cl- efflux from CFBE cells was stimulated by NAC in a dose-dependent manner, with 10 mM NAC causing a significant increase in Cl- efflux with nearly 80% in CFBE cells. The intracellular Cl- concentration in CFBE cells was significantly decreased up to 60% after 4 h treatment with 10 mM NAC. Moreover immunocytochemistry and Western blot experiments revealed expression of CFTR channel on CFBE cells after treatment with 10 mM NAC. The stimulation of Cl- efflux by NAC in CF airway epithelial cells may improve hydration of the mucus and thereby be beneficial for CF patients.

  20. Spatial variation in spring CO2 efflux along the trans-Alaska pipeline, Alaska: Contribution of spring carbon

    Science.gov (United States)

    Kim, Y.

    2013-12-01

    Spring soil CO2 efflux-measurement was conducted in representative sites along the trans-Alaska pipeline during 2010 to 2012 for the understanding of spatial variation in spring CO2 efflux response to change in snow-melting timing. The sites is 3 tundra sites (coastal tundra, upland tundra, upland tundra, and sub-alpine tundra), 2 white spruce sites in tundra-boreal forest ecotone, and Gold Creek, and 3 black spruce sites in Coldfoot, upper and lower reaches of the Yukon River. Soil CO2 efflux-measurement, which is a portable manual chamber CO2 efflux system, was conducted during snow-covered and snow-melting periods, minimizing artificial effects. CO2 effluxes in snow-covered and exposed soils showed a significantly difference, suggesting that spring CO2 efflux is much higher than that in snow-covered soil. The efflux was measured at 4-direction due to the difference of exposed extent, implying the magnitude of CO2 production. Average diameter in breast height (DBH: 85 × 11 cm) of white spruce is much thicker than black spruce (DBH: 33 × 5 cm), suggesting the difference of heat uptake and emission capacity between both forests. Soil temperature at 5 cm below the surface is one of significant keys in determining soil CO2 efflux. The magnitude of spring CO2 efflux showed white spruce, black spruce, and tundra in turn, suggesting that spring CO2 efflux (> 8 gC/m2/day) of corresponds to summer soil CO2 efflux. Then, spring soil CO2 efflux should be not overlooked the contribution of annual soil carbon efflux in spite of difficulties in snow-disappeared timing and springtime.

  1. Antibiotics: Pharmacokinetics, toxicity, resistance and multidrug efflux pumps.

    Science.gov (United States)

    Yılmaz, Çiğdem; Özcengiz, Gülay

    2017-06-01

    The discovery of penicillin followed by streptomycin, tetracycline, cephalosporins and other natural, semi-synthetic and synthetic antimicrobials completely revolutionized medicine by reducing human morbidity and mortality from most of the common infections. However, shortly after they were introduced to clinical practice, the development of resistance was emerged. The decreasing interest from antibiotic industry in spite of rapid global emergence of antibiotic resistance is a tough dilemma from the pointview of public health. The efficiency of antimicrobial treatment is determined by both pharmacokinetics and pharmacodynamics. In spite of their selective toxicity, antibiotics still cause severe, life-threatening adverse reactions in host body mostly due to defective drug metabolism or excessive dosing regimen. The present article aims at updating current knowledge on pharmacokinetics/pharmacodynamics concepts and models, toxicity of antibiotics as well as antibiotic resistance mechanisms, resistome analyses and search for novel antibiotic resistance determinants with special emphasis given to the-state-of-the-art regarding multidrug efflux pumps and their additional physiological functions in stress adaptation and virulence of bacteria. All these issues are highly linked to each other and not only important for most efficient and prolonged use of current antibiotics, but also for discovery and development of new antibiotics and novel inhibitors of antibiotic resistance determinants of pathogens. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Small Changes in the Primary Structure of Transportan 10 Alter the Thermodynamics and Kinetics of its Interaction with Phospholipid Vesicles

    Science.gov (United States)

    2008-01-01

    The kinetics and thermodynamics of binding of transportan 10 (tp10) and four of its variants to phospholipid vesicles, and the kinetics of peptide-induced dye efflux, were compared. Tp10 is a 21-residue, amphipathic, cationic, cell-penetrating peptide similar to helical antimicrobial peptides. The tp10 variants examined include amidated and free peptides, and replacements of tyrosine by tryptophan. Carboxy-terminal amidation or substitution of tryptophan for tyrosine enhance binding and activity. The Gibbs energies of peptide binding to membranes determined experimentally and calculated from the interfacial hydrophobicity scale are in good agreement. The Gibbs energy for insertion into the bilayer core was calculated using hydrophobicity scales of residue transfer from water to octanol and to the membrane/water interface. Peptide-induced efflux becomes faster as the Gibbs energies for binding and insertion of the tp10 variants decrease. If anionic lipids are included, binding and efflux rate increase, as expected because all tp10 variants are cationic and an electrostatic component is added. Whether the most important effect of peptide amidation is the change in charge or an enhancement of helical structure, however, still needs to be established. Nevertheless, it is clear that the changes in efflux rate reflect the differences in the thermodynamics of binding and insertion of the free and amidated peptide groups. PMID:18260641

  3. Methyl bromide release from activated carbon and the soil/water/carbon interface

    Science.gov (United States)

    Methyl Bromide (MB) is a major source of stratospheric bromine radical, a known depletor of ozone. The use of ozone-depleting chemicals, including MB, is regulated by the Montreal Protocol. Critical uses of MB are permitted, such as when postharvest fumigation is mandated by an importing country. Fo...

  4. Comparison of bromide and nitrate transport in the Bainsvlei soil of ...

    African Journals Online (AJOL)

    Bromide is commonly used to simulate the movement of nitrate fertilisers through the soil profile. However, there exists no comparative evaluation of the leaching properties of Br- and NO3-_N under local soil and rainfall conditions at Bloemfontein. The purpose of this work was to conduct a field experiment to evaluate the ...

  5. The history and future of methyl bromide alternatives in the southern United States

    Science.gov (United States)

    Tom E. Starkey

    2012-01-01

    This article gives a brief history of the efforts of the Southern Forest Nursery Management Cooperative (SFNMC) in testing methyl bromide (MBr) alternatives for soil fumigation. In the southeastern United States, fumigation with MBr has been the most commonly used method for producing high quality, pest-free forest seedlings in an environment that is conducive for soil...

  6. Distribution of bromine in mixed iodide-bromide organolead perovskites and its impact on photovoltaic performance

    NARCIS (Netherlands)

    Zhou, Yang; Wang, Feng; Fang, Hong-Hua; Loi, Maria Antonietta; Xie, Fang-Yan; Zhao, Ni; Wong, Ching-Ping

    2016-01-01

    Mixed iodide-bromide (I-Br) organolead perovskites are of great interest for both single junction and tandem solar cells since the optical bandgap of the materials can be tuned by varying the bromine to iodine ratio. Yet, it remains unclear how bromine incorporation modifies the properties of the

  7. Microwave-Enhanced Cross-Coupling Reactions Involving Alkynyltrifluoroborates with Aryl Bromides

    Directory of Open Access Journals (Sweden)

    George W. Kabalka

    2013-01-01

    Full Text Available Palladium-catalyzed alkynylation has emerged as one of the most reliable methods for the synthesis of alkynes which are often used in natural product syntheses and material science. An efficient method for coupling alkynyltrifluoroborates with various aryl bromides in the presence of a palladium catalyst has been developed using microwave irradiation. The microwave reactions are rapid and efficient.

  8. Once-daily glycopyrronium bromide, a long-acting muscarinic antagonist, for chronic obstructive pulmonary disease

    DEFF Research Database (Denmark)

    Ulrik, Charlotte Suppli

    2012-01-01

    Long-acting bronchodilators are central in the pharmacological management of patients with chronic obstructive pulmonary disease (COPD). The aim of this systematic review is to provide an overview of the studies evaluating the safety and clinical efficacy of inhaled glycopyrronium bromide, a novel...

  9. Methyl Bromide Measurements in the Taylor Dome M3C1 Ice Core, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set includes methyl bromide (CH3Br) measurements made on air extracted from 70 samples from the Taylor Dome M3C1 ice core. CH3Br was measured in air from...

  10. Comparison of bromide and nitrate transport in the Bainsvlei soil of ...

    African Journals Online (AJOL)

    DRINIE

    2004-01-01

    Jan 1, 2004 ... 9. Available on website http://www.wrc.org.za. Comparison of bromide and nitrate transport in the Bainsvlei soil of South Africa under natural rainfall. Ketema Tilahun1*, Joseph F Botha1 and Alan TP Bennie2. 1Institute for Groundwater Studies, University of the Free State, PO Box 339, Bloemfontein 9300, ...

  11. 76 FR 34700 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Science.gov (United States)

    2011-06-14

    ... converting to alternatives such as: sulfuryl fluoride and phosphine. If relevant, the applicant should also...: sulfuryl fluoride, micro-sanitation, and heat. If relevant, the applicant should include the costs to.... Applicants must include information on the amount of methyl bromide and any other fumigants used as well as...

  12. Iodine catalyzed and tertiary butyl ammonium bromide promoted p reparation of b enzoxazaphosphininyl phenylboronates

    Directory of Open Access Journals (Sweden)

    K. R. Kishore K. Reddy,

    2009-05-01

    Full Text Available Benzoxazaphosphininyl Phenylboronates were prepared by O-Phosphorylation of potassium salt ofphenylboronic acid with cyclic phosphoromonochloridates in the presence of stoichiometric amount of Iodineand catalytic amount of tertiary butyl ammonium bromide at 50-60 °C in dry toluene.

  13. SYNTHESIS AND CATALYTIC PROPERTIES OF CROSS-LINKED HYDROPHOBICALLY ASSOCIATING POLY(ALKYLMETHYLDIALLYLAMMONIUM BROMIDES)

    NARCIS (Netherlands)

    WANG, GJ; ENGBERTS, JBFN

    1994-01-01

    Cross-linked, hydrophobically associating homo- and copolymers were synthesized by free-radical cyclo(co)polymerization of alkylmethyldiallylammonium bromide monomers with a small amount of N,N'-methylenebisacrylamide in aqueous solution using ammonium persulfate as the initiator. The cross-linked

  14. Palladium-catalyzed carbonylative sonogashira coupling of aryl bromides using near stoichiometric carbon monoxide

    DEFF Research Database (Denmark)

    Neumann, Karoline T.; Laursen, Simon R.; Lindhardt, Anders T.

    2014-01-01

    A general procedure for the palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides is reported, using near stoichiometric amounts of carbon monoxide. The method allows a broad substrate scope in moderate to excellent yields. The formed alkynone motive serves as a platform...

  15. A facile one-pot synthesis of deep blue luminescent lead bromide perovskite microdisks.

    Science.gov (United States)

    Yuan, Zhao; Shu, Yu; Tian, Yu; Xin, Yan; Ma, Biwu

    2015-11-25

    We report a facile one-pot synthetic method to prepare highly luminescent layered lead(II) bromide perovskite microdisks with the lateral size of a few micrometers and thickness of 100-150 nm, featuring narrow deep blue emissions with quantum yields of up to 53% in toluene solutions and thin films at room temperature.

  16. Experimental study of negative temperatures in lithium-bromide absorption refrigerating machines

    Science.gov (United States)

    Stepanov, K. I.; Mukhin, D. G.; Alekseenko, S. V.; Volkova, O. V.

    2015-07-01

    The authors have developed a method and presented experimental data for obtaining negative temperatures of evaporation in lithium-bromide absorption chillers driven by heat recovery. It has been found that the attainable temperature of the refrigerated medium is the value of -5 °C.

  17. Electrical conductivity of miscibility gap salt systems based on lithium fluoride with alkali metal bromides

    Science.gov (United States)

    Babushkina, L. M.; Dokashenko, S. I.; Stepanov, V. P.; Shcherbakov, K. N.

    2011-02-01

    The electrical conductivity κ of miscibility gap ionic melts of lithium fluoride with potassium, rubidium, and cesium bromides is measured. The role of the size and temperature factors in migration is discussed for the systems with a predominant Coulomb interaction of particles in the saturation line.

  18. Bromination of Benzonorbornadiene Using a Mixture of Sodium Bromide and Sodium Perborate at High Temperatures

    OpenAIRE

    Şenocak, Erdal; Yavuz TAŞKESENLİGİL

    2014-01-01

    Bromination of benzonorbornadiene (1) with sodium bromide in the presence of sodium perborate at room temperature gave only one product, the dibromide 2 produced via Wagner-Meerwein rearrangement. However, at high temperatures, bromination resulted predominantly in the formation of rearranged solvolytic products whose formation mechanisms are discussed.

  19. 78 FR 32646 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Science.gov (United States)

    2013-05-31

    ... control effectiveness between methyl bromide and sulfuryl fluoride or heat treatments. The cost of... three uses (strawberries, fresh dates and dry cured ham). Since information about alternatives, economic.../ temperature treatment system. Applicants should include the costs to retrofit equipment or design and...

  20. Detection of DNA cross-links in tumor cells with the ethidium bromide fluorescence assay

    NARCIS (Netherlands)

    de Jong, Steven; Zijlstra, J G; Timmer-Bosscha, H; Mulder, N H; de Vries, Liesbeth

    1986-01-01

    Until now the fluorescence assay with ethidium bromide has only been used on pure DNA. This assay depends on the difference in fluorescence between single- and double-stranded DNA (dsDNA). Cross-links in DNA are measured by the return of fluorescence of dsDNA after heat denaturation at pH 12. Under

  1. Vertical profile of branch CO2 efflux in a Norway spruce tree: a case study

    Science.gov (United States)

    Acosta, M.; Pavelka, M.

    2012-04-01

    Despite woody-tissue CO2 effluxes having been recognized as an important component of forest carbon budget due to the fraction of assimilates used and the dramatic increase in woody with stand development, there is limited research to determine the CO2 efflux vertical variability of woody-tissue components. For a better understanding and quantification of branch woody-tissue CO2 efflux in forest ecosystems, it is necessary to identify the environmental factors influencing it and the role of the branch distribution within the canopy. The proper assessment of this forest component will improve the knowledge of the ratio between ecosystem respiration and gross primary production at forest ecosystem. In order to achieve this goal, branch CO2 efflux of Norway spruce tree was measured in ten branches at five different whorls during the growing season 2004 (from June till October) in campaigns of 3-4 times per month at the Beskydy Mts., the Czech Republic, using a portable infrared gas analyzer operating as a closed system. Branch woody tissue temperature was measured continuously in ten minutes intervals for each sample position during the whole experiment period. On the basis of relation between CO2 efflux rate and woody tissue temperature a value of Q10 and normalized CO2 efflux rate (E10 - CO2 efflux rate at 10° C) were calculated for each sampled position. Estimated Q10 values ranged from 2.12 to 2.89 and E10 ranged from 0.41 to 1.19 ?molCO2m-2 s-1. Differences in branch CO2 efflux were found between orientations; East side branches presented higher efflux rate than west side branches. The highest branch CO2 efflux rate values were measured in August and the lowest in October, which were connected with woody tissue temperature and ontogenetic processes during these periods. Branch CO2 efflux was significantly and positively correlated with branch position within canopy and woody tissue temperature. Branches from the upper whorls showed higher respiration activity

  2. Characterization of soluble bromide measurements and a case study of BrO observations during ARCTAS

    Directory of Open Access Journals (Sweden)

    J. Liao

    2012-02-01

    Full Text Available A focus of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS mission was examination of bromine photochemistry in the spring time high latitude troposphere based on aircraft and satellite measurements of bromine oxide (BrO and related species. The NASA DC-8 aircraft utilized a chemical ionization mass spectrometer (CIMS to measure BrO and a mist chamber (MC to measure soluble bromide. We have determined that the MC detection efficiency to molecular bromine (Br2, hypobromous acid (HOBr, bromine oxide (BrO, and hydrogen bromide (HBr as soluble bromide (Br was 0.9±0.1, 1.06+0.30/−0.35, 0.4±0.1, and 0.95±0.1, respectively. These efficiency factors were used to estimate soluble bromide levels along the DC-8 flight track of 17 April 2008 from photochemical calculations constrained to in situ BrO measured by CIMS. During this flight, the highest levels of soluble bromide and BrO were observed and atmospheric conditions were ideal for the space-borne observation of BrO. The good agreement (R2 = 0.76; slope = 0.95; intercept = −3.4 pmol mol−1 between modeled and observed soluble bromide, when BrO was above detection limit (>2 pmol mol−1 under unpolluted conditions (NO<10 pmol mol−1, indicates that the CIMS BrO measurements were consistent with the MC soluble bromide and that a well characterized MC can be used to derive mixing ratios of some reactive bromine compounds. Tropospheric BrO vertical column densities (BrOVCD derived from CIMS BrO observations compare well with BrOTROPVCD from OMI on 17 April 2008.

  3. An ace up their sleeve: a transcriptomic approach exposes the AceI efflux protein of Acinetobacter baumannii and reveals the drug efflux potential hidden in many microbial pathogens

    Directory of Open Access Journals (Sweden)

    Karl A Hassan

    2015-04-01

    Full Text Available The era of antibiotics as a cure-all for bacterial infections appears to be coming to an end. The emergence of multidrug resistance in many hospital-associated pathogens has resulted in superbugs that are effectively untreatable. Multidrug efflux pumps are well known mediators of bacterial drug resistance. Genome sequencing efforts have highlighted an abundance of putative efflux pump genes in bacteria. However, it is not clear how many of these pumps play a role in antimicrobial resistance. Several studies have demonstrated that efflux pump genes that participate in drug resistance are typically under tight regulatory control and expressed only in response to their substrates. Consequently, changes in gene expression following antimicrobial shock treatments may be used to identify efflux pumps that mediate antimicrobial resistance, informing targeted functional analyses of these proteins. Using this approach we have characterised novel efflux pumps in both Gram-negative and Gram-positive bacteria. Notably, we recently applied this strategy to characterise the AceI efflux pump from Acinetobacter. AceI is a prototype for a new family of multidrug efflux proteins that is conserved across many proteobacterial lineages. Different efflux pumps in this family have been shown to confer resistance to biocides including chlorhexidine, dequalinium, benzalkonium, proflavine and/or acriflavine. The discovery of this novel family of multidrug efflux proteins raises the possibility that additional undiscovered intrinsic resistance proteins may be encoded in the core genomes of pathogenic bacteria.

  4. Arctigenin promotes cholesterol efflux from THP-1 macrophages through PPAR-γ/LXR-α signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xiaolin [Department of Cardiothoracic Surgery, Huashan Hospital, Fudan University, Shanghai 200032 (China); Li, Qian [Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai (China); Pang, Liewen; Huang, Guoqian; Huang, Jiechun; Shi, Meng; Sun, Xiaotian [Department of Cardiothoracic Surgery, Huashan Hospital, Fudan University, Shanghai 200032 (China); Wang, Yiqing, E-mail: yiqingwangbiopaper@163.com [Department of Cardiothoracic Surgery, Huashan Hospital, Fudan University, Shanghai 200032 (China)

    2013-11-15

    Highlights: •Arctigenin enhanced cholesterol efflux in oxLDL-loaded THP-1 macrophages. •The expression of ABCA1, ABCG1 and apoE was upregulated in arctigenin-treated cells. •Arctigenin promoted the expression of PPAR-γ and LXR-α. •Inhibition of PPAR-γ or LXR-α reversed arctigenin-mediated biological effects. •Arctigenin promotes cholesterol efflux via activation of PPAR-γ/LXR-α/ABCA1 pathway. -- Abstract: Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-density lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α.

  5. The Ins and Outs of RND Efflux Pumps in Escherichia coli

    Directory of Open Access Journals (Sweden)

    João eAnes

    2015-06-01

    Full Text Available Infectious diseases remain one of the principal causes of morbidity and mortality in the world. Relevant authorities including the WHO and CDC have expressed serious concern regarding the continued increase in the development of multidrug resistance among bacteria. They have also reaffirmed the urgent need for investment in the discovery and development of new antibiotics and therapeutic approaches to treat multidrug resistant (MDR bacteria.The extensive use of antimicrobial compounds in diverse environments, including farming and healthcare, has been identified as one of the main causes for the emergence of MDR bacteria. Induced selective pressure has led bacteria to develop new strategies of defence against these chemicals. Bacteria can accomplish this by several mechanisms, including enzymatic inactivation of the target compound; decreased cell permeability; target protection and/or overproduction; altered target site/enzyme and increased efflux due to over-expression of efflux pumps.Efflux pumps can be specific for a single substrate or can confer resistance to multiple antimicrobials by facilitating the extrusion of a broad range of compounds including antibiotics, heavy metals, biocides and others, from the bacterial cell. To overcome antimicrobial resistance caused by active efflux, efforts are required to better understand the fundamentals of drug efflux mechanisms. There is also a need to elucidate how these mechanisms are regulated and how they respond upon exposure to antimicrobials. Understanding these will allow the development of combined therapies using efflux inhibitors together with antibiotics to act on Gram-negative bacteria, such as the emerging globally disseminated MDR pathogen Escherichia coli ST131 (O25:H4. This review will summarise the current knowledge on resistance-nodulation-cell division efflux mechanisms in E. coli, a bacteria responsible for community and hospital-acquired infections, as well as foodborne

  6. The ins and outs of RND efflux pumps in Escherichia coli.

    Science.gov (United States)

    Anes, João; McCusker, Matthew P; Fanning, Séamus; Martins, Marta

    2015-01-01

    Infectious diseases remain one of the principal causes of morbidity and mortality in the world. Relevant authorities including the WHO and CDC have expressed serious concern regarding the continued increase in the development of multidrug resistance among bacteria. They have also reaffirmed the urgent need for investment in the discovery and development of new antibiotics and therapeutic approaches to treat multidrug resistant (MDR) bacteria. The extensive use of antimicrobial compounds in diverse environments, including farming and healthcare, has been identified as one of the main causes for the emergence of MDR bacteria. Induced selective pressure has led bacteria to develop new strategies of defense against these chemicals. Bacteria can accomplish this by several mechanisms, including enzymatic inactivation of the target compound; decreased cell permeability; target protection and/or overproduction; altered target site/enzyme and increased efflux due to over-expression of efflux pumps. Efflux pumps can be specific for a single substrate or can confer resistance to multiple antimicrobials by facilitating the extrusion of a broad range of compounds including antibiotics, heavy metals, biocides and others, from the bacterial cell. To overcome antimicrobial resistance caused by active efflux, efforts are required to better understand the fundamentals of drug efflux mechanisms. There is also a need to elucidate how these mechanisms are regulated and how they respond upon exposure to antimicrobials. Understanding these will allow the development of combined therapies using efflux inhibitors together with antibiotics to act on Gram-negative bacteria, such as the emerging globally disseminated MDR pathogen Escherichia coli ST131 (O25:H4). This review will summarize the current knowledge on resistance-nodulation-cell division efflux mechanisms in E. coli, a bacteria responsible for community and hospital-acquired infections, as well as foodborne outbreaks worldwide.

  7. Cholesterol efflux is differentially regulated in neurons and astrocytes: implications for brain cholesterol homeostasis

    Science.gov (United States)

    Chen, Jing; Zhang, Xiaolu; Kusumo, Handojo; Costa, Lucio G.; Guizzetti, Marina

    2012-01-01

    Disruption of cholesterol homeostasis in the central nervous system (CNS) has been associated with neurological, neurodegenerative, and neurodevelopmental disorders. The CNS is a closed system with regard to cholesterol homeostasis, as cholesterol-delivering lipoproteins from the periphery cannot pass the blood-brain-barrier and enter the brain. Different cell types in the brain have different functions in the regulation of cholesterol homeostasis, with astrocytes producing and releasing apolipoprotein E and lipoproteins, and neurons metabolizing cholesterol to 24(S)-hydroxycholesterol. We present evidence that astrocytes and neurons adopt different mechanisms also in regulating cholesterol efflux. We found that in astrocytes cholesterol efflux is induced by both lipid-free apolipoproteins and lipoproteins, while cholesterol removal from neurons is triggered only by lipoproteins. The main pathway by which apolipoproteins induce cholesterol efflux is through ABCA1. By upregulating ABCA1 levels and by inhibiting its activity and silencing its expression, we show that ABCA1 is involved in cholesterol efflux from astrocytes but not from neurons. Furthermore, our results suggest that ABCG1 is involved in cholesterol efflux to apolipoproteins and lipoproteins from astrocytes but not from neurons, while ABCG4, whose expression is much higher in neurons than astrocytes, is involved in cholesterol efflux from neurons but not astrocytes. These results indicate that different mechanisms regulate cholesterol efflux from neurons and astrocytes, reflecting the different roles that these cell types play in brain cholesterol homeostasis. These results are important in understanding cellular targets of therapeutic drugs under development for the treatments of conditions associated with altered cholesterol homeostasis in the CNS. PMID:23010475

  8. Efflux pump, the masked side of beta-lactam resistance in Klebsiella pneumoniae clinical isolates.

    Directory of Open Access Journals (Sweden)

    Jean-Marie Pages

    Full Text Available BACKGROUND: Beta-lactamase production and porin decrease are the well-recognized mechanisms of acquired beta-lactam resistance in Klebsiella pneumoniae isolates. However, such mechanisms proved to be absent in K. pneumoniae isolates that are non susceptible to cefoxitin (FOX and susceptible to amoxicillin+clavulanic acid in our hospital. Assessing the role of efflux pumps in this beta-lactam phenotype was the aim of this study. METHODOLOGY/FINDINGS: MICs of 9 beta-lactams, including cloxacillin (CLX, and other antibiotic families were tested alone and with an efflux pump inhibitor (EPI, then with both CLX (subinhibitory concentrations and EPI against 11 unique bacteremia K. pneumoniae isolates displaying the unusual phenotype, and 2 ATCC strains. CLX and EPI-dose dependent effects were studied on 4 representatives strains. CLX MICs significantly decreased when tested with EPI. A similar phenomenon was observed with piperacillin+tazobactam whereas MICs of the other beta-lactams significantly decreased only in the presence of both EPI and CLX. Thus, FOX MICs decreased 128 fold in the K. pneumoniae isolates but also 16 fold in ATCC strain. Restoration of FOX activity was CLX dose-dependent suggesting a competitive relationship between CLX and the other beta-lactams with regard to their efflux. For chloramphenicol, erythromycin and nalidixic acid whose resistance was also due to efflux, adding CLX to EPI did not increase their activity suggesting differences between the efflux process of these molecules and that of beta-lactams. CONCLUSION: This is the first study demonstrating that efflux mechanism plays a key role in the beta-lactam susceptibility of clinical isolates of K. pneumoniae. Such data clearly evidence that the involvement of efflux pumps in beta-lactam resistance is specially underestimated in clinical isolates.

  9. Responses of soil CO(2) efflux to precipitation pulses in two subtropical forests in southern China.

    Science.gov (United States)

    Deng, Qi; Zhou, Guoyi; Liu, Shizhong; Chu, Guowei; Zhang, Deqiang

    2011-12-01

    This study was designed to examine the responses of soil CO(2) efflux to precipitation pulses of varying intensities using precipitation simulations in two subtropical forests [i.e., mixed and broadleaf forests (MF and BF)] in southern China. The artificial precipitation event was achieved by spraying a known amount of water evenly in a plot (50 × 50 cm(2)) over a 30 min period, with intensities ranging from 10, 20, 50 and 100 mm within the 30 min. The various intensities were simulated in both dry season (in December 2007) and wet (in May 2008) season. We characterized the dynamic patterns of soil CO(2) efflux rate and environmental factors over the 5 h experimental period. Results showed that both soil moisture and soil CO(2) efflux rate increased to peak values for most of the simulated precipitation treatments, and gradually returned to the pre-irrigation levels after irrigation in two forests. The maximum peak of soil CO(2) efflux rate occurred at the 10 mm precipitation event in the dry season in BF and was about 3.5 times that of the pre-irrigation value. The change in cumulative soil CO(2) efflux following precipitation pulses ranged from -0.68 to 1.72 g CO(2) m(-2) over 5 h compared to the pre-irrigation levels and was generally larger in the dry season than in the wet season. The positive responses of soil CO(2) efflux to precipitation pulses declined with the increases in precipitation intensity, and surprisingly turned to negative when precipitation intensity reached 50 and 100 mm in the wet season. These findings indicated that soil CO(2) efflux could be changed via pulse-like fluxes in subtropical forests in southern China as fewer but extreme precipitation events occur in the future.

  10. Landscape structure control on soil CO2 efflux variability in complex terrain: Scaling from point observations to watershed scale fluxes

    Science.gov (United States)

    Diego A. Riveros-Iregui; Brian L. McGlynn

    2009-01-01

    We investigated the spatial and temporal variability of soil CO2 efflux across 62 sites of a 393-ha complex watershed of the northern Rocky Mountains. Growing season (83 day) cumulative soil CO2 efflux varied from ~300 to ~2000 g CO2 m-2, depending upon landscape position, with a median of 879.8 g CO2 m-2. Our findings revealed that highest soil CO2 efflux rates were...

  11. Regulation of the efflux of putrescine and cadaverine from rapidly growing cultured RAW 264 cells by extracellular putrescine.

    OpenAIRE

    Tjandrawinata, R R; Byus, C V

    1995-01-01

    Cultures of the macrophage-like RAW 264 cells were adapted to divide normally in a synthetic serum-supplemented culture medium lacking any polyamines and diamine oxidase activity. These rapidly dividing cells actively effluxed large amounts of putrescine and cadaverine, compared with the intracellular levels, into the culture medium. The efflux of putrescine was stimulated by the amino acid ornithine, whereas efflux of cadaverine was inhibited. Relatively low levels of spermidine and N1-acety...

  12. Effect of rosuvastatin treatment on cholesterol efflux from human macrophages.

    Science.gov (United States)

    Kralova Lesna, Ivana; Adamkova, Vera; Pagacova, Libuse

    2011-01-01

    One of the positive effects of rosuvastatin is an increase in HDL cholesterol (HDL-C). An increase in HDL-C is considered as one of the positive effects of this type of statin, although it does not necessarily correspond to the actual reverse cholesterol transport (RCT) rate. We analyzed the influence of statin induced changes in HDL-C on cholesterol efflux (CHE), the key step affecting the RCT. Fourteen subjects (7 men, age: 50.9 ± 8.4 years and 7 women, age: 59.7 ± 10.6 years) with mixed dyslipidemia received 20 mg of rosuvastatin daily for 3 months. Before the initiation of statin therapy and at the end of the study period, the CHE from 14C cholesterol-labeled macrophages was determined in addition to parameters related to lipid metabolism. CHE was calculated as the percentage of radioactivity released from the macrophages into the media containing 5% of the examined plasma. The rosuvastatin administration resulted in significant reductions of total cholesterol, LDL cholesterol, and apolipoprotein B and a significant increase in HDL-C (from 1.43 mmol/l to 1.52 mmol/l, p=0.05), while the levels of apolipoprotein A1 remained unchanged. There was no significant increase in CHE (from 16.1% to 17.6%, p for trend = 0.053). Individual changes in HDL-C correlated significantly (p<0.05) with individual changes of CHE (r=0.76). Administration of rosuvastatin increases HDL-C, and individual changes correlate with the individual increases of CHE from macrophages. © 2011 Neuroendocrinology Letters

  13. Effect of Ispaghula and Oxyphenonium Bromide on the Symptoms of Irritable Bowel Syndrome - A Comparative Study

    Directory of Open Access Journals (Sweden)

    B Paik

    2010-07-01

    Full Text Available Background: Irritable bowel syndrome is a chronic continuous or remittent gastrointestinal illness characterized byfrequent unexplained symptoms that include abdominal pain, bloating, and bowel disturbance, in our country, no studyhas been conducted using the Ispaghula husk and oxyphenonium bromide for the treatment of IBS patients. Objectives:To compare the efficacy of treatment with Ispaghula husk and Oxyphenonium bromide. Methods: Total sixty patientsdiagnosed clinically as irritable bowel syndrome irrespective of subtype who fulfilled the Rome II criteria were includedequally into two groups-Group-I (Ispaghula group & Group-II (Oxyphenonium group. In Group-I patients were given30gm of Ispaghula husk at night daily and in Group-II patients were given 5mg of oxyphenonium bromide. After sixweeks the clinical parameters of both the groups recorded in the case record forms were taken for analysis. Results: Themean age of the patients in the Group- I were 33.4±11.9 yrs and that of the patients in the Group-II were 31.0±17.5 yrs.Male and female ratio in group I was 14:1 and in group II was 23:7. Most of the patients were recorded in the age groupof 26-30 in both groups. Symptom free patients were graded in 16.7% patients in Group-I and in 20% patients in Group-II. No improvement was occurred in 16.7% patients in Group-I and in 10% patients in Group-II. Conclusions: Ispaghulahusk shows the better efficacy to improve the symptoms of IBS like abdominal pain or discomfort and sense of well beingthan Oxyphenonium bromide. Oxephenonium bromide shows the better efficacy to decrease the stool frequency frombase line than Ispaghula husk.DOI: 10.3329/bsmmuj.v3i1.5506BSMMU J 2010; 3(1: 3-8

  14. A novel explicit approach to model bromide and pesticide transport in connected soil structures

    Directory of Open Access Journals (Sweden)

    J. Klaus

    2011-07-01

    Full Text Available The present study tests whether an explicit treatment of worm burrows and tile drains as connected structures is feasible for simulating water flow, bromide and pesticide transport in structured heterogeneous soils at hillslope scale. The essence is to represent worm burrows as morphologically connected paths of low flow resistance in a hillslope model. A recent Monte Carlo study (Klaus and Zehe, 2010, Hydrological Processes, 24, p. 1595–1609 revealed that this approach allowed successful reproduction of tile drain event discharge recorded during an irrigation experiment at a tile drained field site. However, several "hillslope architectures" that were all consistent with the available extensive data base allowed a good reproduction of tile drain flow response. Our second objective was thus to find out whether this "equifinality" in spatial model setups may be reduced when including bromide tracer data in the model falsification process. We thus simulated transport of bromide for the 13 spatial model setups that performed best with respect to reproduce tile drain event discharge, without any further calibration. All model setups allowed a very good prediction of the temporal dynamics of cumulated bromide leaching into the tile drain, while only four of them matched the accumulated water balance and accumulated bromide loss into the tile drain. The number of behavioural model architectures could thus be reduced to four. One of those setups was used for simulating transport of Isoproturon, using different parameter combinations to characterise adsorption according to the Footprint data base. Simulations could, however, only reproduce the observed leaching behaviour, when we allowed for retardation coefficients that were very close to one.

  15. The role of bromide ions in seeding growth of Au nanorods.

    Science.gov (United States)

    Garg, Niti; Scholl, Clark; Mohanty, Ashok; Jin, Rongchao

    2010-06-15

    We report our findings on the important role of bromide ions in the seeding growth process of Au nanorods. The seed-mediated process constitutes a well-developed method for synthesizing gold nanorods in high yield, which is facilitated by a micelle-forming surfactant, cetyltrimethylammonium bromide (CTA-Br). Despite the tremendous work in recent years, the growth mechanism of Au nanorods has not been fully understood. Contrary to the widely accepted mechanism of CTA(+) micelle-templated growth of Au nanorods, we have identified the critical role of bromide ions in the seeding growth of Au nanorods. We found that even when the micelle-forming agent (CTA(+)) concentration is below its critical micelle concentration (cmc), bromide ions added in the form of NaBr can successfully effect the growth of Au nanorods in good yield. By controlling the concentration of externally added bromide ions, the rod shape and dimensions of the resulting Au nanoparticles can be readily controlled in the presence of only a minimum amount of CTABr (as a steric stabilizer for nanorods). High-resolution TEM studies show that the as-formed nanorods are perfectly single crystalline, instead of penta-twinned ones, and are bound by {111} and {100} facets with a [110] direction as the elongation direction. A mechanism is proposed to account for the seeding growth of single crystalline Au nanorods. Overall, this work explicitly demonstrates that Br(-) indeed serves as an important shape-directing agent for gold nanorod formation in the seed-mediated process.

  16. Free energy changes in denaturation of ribonuclease A by mixed denaturants. Effects of combinations of guanidine hydrochloride and one of the denaturants lithium bromide, lithium chloride, and sodium bromide.

    Science.gov (United States)

    Ahmad, F

    1984-04-10

    The denaturation of ribonuclease A by guanidine hydrochloride, lithium bromide, and lithium chloride and by mixed denaturants consisting of guanidine hydrochloride and one of the denaturants lithium chloride, lithium bromide, and sodium bromide was followed by difference spectral measurements at pH 4.8 and 25 degrees C. Both components of mixed denaturant systems enhance each other's effect in unfolding the protein. The effect of lithium bromide on the midpoint of guanidine hydrochloride denaturation transition is approximately the sum of the effects of the constituent ions. For all the mixed denaturants tested, the dependence of the free energy change on denaturation is linear. The conformational free energy associated with the guanidine hydrochloride denaturation transition in water is 7.5 +/- 0.1 kcal mol-1, and it is unchanged in the presence of low concentrations of lithium bromide, lithium chloride, and sodium bromide which by themselves are not concentrated enough to unfold the protein. The conformational free energy associated with the lithium bromide denaturation transition in water is 11.7 +/- 0.3 kcal mol-1, and it is not affected by the presence of low concentrations of guanidine hydrochloride which by themselves do not disrupt the structure of native ribonuclease A.

  17. Apolipoprotein A-I configuration and cell cholesterol efflux activity of discoidal lipoproteins depend on the reconstitution process.

    Science.gov (United States)

    Cuellar, Luz Ángela; Prieto, Eduardo Daniel; Cabaleiro, Laura Virginia; Garda, Horacio Alberto

    2014-01-01

    Discoidal high-density lipoproteins (D-HDL) are critical intermediates in reverse cholesterol transport. Most of the present knowledge of D-HDL is based on studies with reconstituted lipoprotein complexes of apolipoprotein A-I (apoA-I) obtained by cholate dialysis (CD). D-HDL can also be generated by the direct microsolubilization (DM) of phospholipid vesicles at the gel/fluid phase transition temperature, a process mechanistically similar to the "in vivo" apoAI lipidation via ABCA1. We compared the apoA-I configuration in D-HDL reconstituted with dimyristoylphosphatidylcholine by both procedures using fluorescence resonance energy transfer measurements with apoA-I tryptophan mutants and fluorescently labeled cysteine mutants. Results indicate that apoA-I configuration in D-HDL depends on the reconstitution process and are consistent with a "double belt" molecular arrangement with different helix registry. As reported by others, a configuration with juxtaposition of helices 5 of each apoAI monomer (5/5 registry) predominates in D-HDL obtained by CD. However, a configuration with helix 5 of one monomer juxtaposed with helix 2 of the other (5/2 registry) would predominate in D-HDL generated by DM. Moreover, we also show that the kinetics of cholesterol efflux from macrophage cultures depends on the reconstitution process, suggesting that apoAI configuration is important for this HDL function. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Partitioning CO2 effluxes from an Atlantic pine forest soil between endogenous soil organic matter and recently incorporated 13C-enriched plant material.

    Science.gov (United States)

    Fernandez, Irene; Cabaneiro, Ana; González-Prieto, Serafín J

    2006-04-15

    Soil CO2 effluxes from recently added 13C-labeled phytomass versus endogenous soil organic matter (SOM) were studied in an acid soil from Atlantic pine forests (NW Spain). After several cultures to incorporate fresh 13C-enriched Lolium perenne to a Humic Cambisol with predominance of humus--Al over humus--Fe complexes, potential soil C mineralization was determined by laboratory aerobic incubation (84 days). Isotopic 13C analyses of SOM fractions were assessed to know in which organic compartments the 13C was preferentially incorporated. Although in the 13C-labeled soil the C mineralization coefficient totalized less than 3% of soil C, the 13C mineralization coefficient exceeded 14%, indicating a greater lability of the newly incorporated organic matter. Organic compounds coming from added phytomass showed a higher lability and contributed considerably to the total soil CO2 effluxes (52% of total soil CO2 evolved during the first decomposition stages and 27% at the end), even though added-C comprised less than 4% of total soil C. Good determination coefficients, when values of CO2--C released were fitted to a first-order double exponential kinetic model, support the existence of two C pools of different lability. Kinetic parameters obtained with this model indicated that phytomass addition augmented the biodegradability of the labile pool (instantaneous mineralization rate k increased from 0.07 d(-1) to 0.12 d(-1)) but diminished that of the recalcitrant pool (instantaneous mineralization rate h decreased from 2.7 x 10(-4) d(-1) to 1.6 x 10(-4) d(-1)). Consequently, the differentiation between both SOM pools increased, showing the importance of SOM quality on CO2 emissions from this kind of soil to the atmosphere.

  19. Emergence of a Potent Multidrug Efflux Pump Variant That Enhances Campylobacter Resistance to Multiple Antibiotics.

    Science.gov (United States)

    Yao, Hong; Shen, Zhangqi; Wang, Yang; Deng, Fengru; Liu, Dejun; Naren, Gaowa; Dai, Lei; Su, Chih-Chia; Wang, Bing; Wang, Shaolin; Wu, Congming; Yu, Edward W; Zhang, Qijing; Shen, Jianzhong

    2016-09-20

    Bacterial antibiotic efflux pumps are key players in antibiotic resistance. Although their role in conferring multidrug resistance is well documented, the emergence of "super" efflux pump variants that enhance bacterial resistance to multiple drugs has not been reported. Here, we describe the emergence of a resistance-enhancing variant (named RE-CmeABC) of the predominant efflux pump CmeABC in Campylobacter, a major zoonotic pathogen whose resistance to antibiotics is considered a serious antibiotic resistance threat in the United States. Compared to the previously characterized CmeABC transporters, RE-CmeABC is much more potent in conferring Campylobacter resistance to antibiotics, which was shown by increased MICs and reduced intracellular accumulation of antibiotics. Structural modeling suggests that sequence variations in the drug-binding pocket of CmeB possibly contribute to the enhanced efflux function. Additionally, RE-CmeABC expands the mutant selection window of ciprofloxacin, enhances the emergence of antibiotic-resistant mutants, and confers exceedingly high-level resistance to fluoroquinolones, an important class of antibiotics for clinical therapy of campylobacteriosis. Furthermore, RE-CmeABC is horizontally transferable, shifts antibiotic MIC distribution among clinical isolates, and is increasingly prevalent in Campylobacter jejuni isolates, suggesting that it confers a fitness advantage under antimicrobial selection. These findings reveal a new mechanism for enhanced multidrug resistance and an effective strategy utilized by bacteria for adaptation to selection from multiple antibiotics. Bacterial antibiotic efflux pumps are ubiquitously present in bacterial organisms and protect bacteria from the antibacterial effects of antimicrobials and other toxic compounds by extruding them out of cells. Thus, these efflux transporters represent an important mechanism for antibiotic resistance. In this study, we discovered the emergence and increasing

  20. Holarrhena antidysenterica as a resistance modifying agent against Acinetobacter baumannii: Its effects on bacterial outer membrane permeability and efflux pumps.

    Science.gov (United States)

    Chusri, Sasitorn; Na-Phatthalung, Pinanong; Siriyong, Thanyaluck; Paosen, Supakit; Voravuthikunchai, Supayang P

    2014-01-01

    Increasing rates of infections caused by multidrug resistant Acinetobacter baumannii (MDRAB) and extensively drug resistant A. baumannii (XDRAB) have caused the need for searching alternative agents. The purposed of this project was to search plant-derived natural products that act as resistant modifying agents (RMAs) against A. baumannii. In this study, we further evaluated the activity of Holarrhena antidysenterica that has been previously proposed as RMA of novobiocin for a model strain, A. baumannii ATCC 19606 on clinically isolated non-MDRAB, MDRAB, and XDRAB. Effects of H. antidysenterica on outer membrane permeability and efflux pumps of the pathogen were conducted to preliminary elucidate mechanisms of this resistant modifier. Novobiocin was selected as a model antibiotic because it is well-established as an effective agent against Gram-positive pathogens. But, it possessed low level of antibacterial activity against Gram-negative pathogens due to an effective permeability barrier of these pathogens. H. antidysenterica ethanol extract possessed weak intrinsic antibacterial activity with minimum inhibitory concentration (MIC) more than 1000 μg/mL. The extract, at concentrations of 250, 125, and 62.5 μg/mL, remarkably enhanced the inhibitory effects of novobiocin (1/4 × MIC; 1-4 μg/mL) against XDRAB isolates. Synergistic effects of novobiocin at 1/4 × MIC and 1/8 × MIC in combination with H. antidysenterica either at 31.2, 15.6, or 7.8 μg/mL against clinical isolates non-MDRAB, MDRAB, and XDRAB were evidenced for 80% of the combinations (189 out of 234 combinations). Although, no enhancement of the accumulation of ethidium bromide was observed after treated with H. antidysenterica, this plant extract weakened the outer membrane of the pathogen as indicated by an increase in the N-phenyl-1-naphthylamine uptake. Our results suggested that H. antidysenterica which primarily interrupts membrane permeability should be further investigated as a promising

  1. Arctigenin promotes cholesterol efflux from THP-1 macrophages through PPAR-γ/LXR-α signaling pathway.

    Science.gov (United States)

    Xu, Xiaolin; Li, Qian; Pang, Liewen; Huang, Guoqian; Huang, Jiechun; Shi, Meng; Sun, Xiaotian; Wang, Yiqing

    2013-11-15

    Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-density lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Interaction of antibacterial compounds with RND efflux pumps in Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Juerg eDreier

    2015-07-01

    Full Text Available Pseudomonas aeruginosa infections are becoming increasingly difficult to treat due to intrinsic antibiotic resistance and the propensity of this pathogen to accumulate diverse resistance mechanisms. Hyperexpression of efflux pumps of the Resistance-Nodulation-Division-type multidrug efflux pumps (e.g. MexAB-OprM, chromosomally encoded by mexAB-oprM, mexCD-oprJ, mexEF-oprN, and mexXY (-oprA is often detected in clinical isolates and contributes to worrying multi-drug resistance phenotypes.Not all antibiotics are affected to the same extent by the aforementioned RND efflux pumps. The impact of efflux on antibiotic activity varies not only between different classes of antibiotics but also between members of the same family of antibiotics. Subtle differences in physicochemical features of compound-pump and compound-solvent interactions largely determine how compounds are affected by efflux activity.The combination of different high-resolution techniques helps to gain insight into the functioning of these molecular machineries. This review discusses substrate recognition patterns based on experimental evidence and computer simulations with a focus on MexB, the pump subunit of the main RND transporter in P. aeruginosa.

  3. Structures and transport dynamics of a Campylobacter jejuni multidrug efflux pump

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chih-Chia; Yin, Linxiang; Kumar, Nitin; Dai, Lei; Radhakrishnan, Abhijith; Bolla, Jani Reddy; Lei, Hsiang-Ting; Chou, Tsung-Han; Delmar, Jared A.; Rajashankar, Kanagalaghatta R.; Zhang, Qijing; Shin, Yeon-Kyun; Yu, Edward W. (Cornell); (Iowa State)

    2017-08-01

    Resistance-nodulation-cell division efflux pumps are integral membrane proteins that catalyze the export of substrates across cell membranes. Within the hydrophobe-amphiphile efflux subfamily, these resistance-nodulation-cell division proteins largely form trimeric efflux pumps. The drug efflux process has been proposed to entail a synchronized motion between subunits of the trimer to advance the transport cycle, leading to the extrusion of drug molecules. Here we use X-ray crystallography and single-molecule fluorescence resonance energy transfer imaging to elucidate the structures and functional dynamics of the Campylobacter jejuni CmeB multidrug efflux pump. We find that the CmeB trimer displays a very unique conformation. A direct observation of transport dynamics in individual CmeB trimers embedded in membrane vesicles indicates that each CmeB subunit undergoes conformational transitions uncoordinated and independent of each other. On the basis of our findings and analyses, we propose a model for transport mechanism where CmeB protomers function independently within the trimer.

  4. Microbial efflux systems and inhibitors: approaches to drug discovery and the challenge of clinical implementation.

    Science.gov (United States)

    Kourtesi, Christina; Ball, Anthony R; Huang, Ying-Ying; Jachak, Sanjay M; Vera, D Mariano A; Khondkar, Proma; Gibbons, Simon; Hamblin, Michael R; Tegos, George P

    2013-01-01

    Conventional antimicrobials are increasingly ineffective due to the emergence of multidrug-resistance among pathogenic microorganisms. The need to overcome these deficiencies has triggered exploration for novel and unconventional approaches to controlling microbial infections. Multidrug efflux systems (MES) have been a profound obstacle in the successful deployment of antimicrobials. The discovery of small molecule efflux system blockers has been an active and rapidly expanding research discipline. A major theme in this platform involves efflux pump inhibitors (EPIs) from natural sources. The discovery methodologies and the available number of natural EPI-chemotypes are increasing. Advances in our understanding of microbial physiology have shed light on a series of pathways and phenotypes where the role of efflux systems is pivotal. Complementing existing antimicrobial discovery platforms such as photodynamic therapy (PDT) with efflux inhibition is a subject under investigation. This core information is a stepping stone in the challenge of highlighting an effective drug development path for EPIs since the puzzle of clinical implementation remains unsolved. This review summarizes advances in the path of EPI discovery, discusses potential avenues of EPI implementation and development, and underlines the need for highly informative and comprehensive translational approaches.

  5. Increased maternal and fetal cholesterol efflux capacity and placental CYP27A1 expression in preeclampsia.

    Science.gov (United States)

    Mistry, Hiten D; Kurlak, Lesia O; Mansour, Yosef T; Zurkinden, Line; Mohaupt, Markus G; Escher, Geneviève

    2017-06-01

    Preeclampsia is a pregnancy-specific condition that leads to increased cardiovascular risk in later life. A decrease in cholesterol efflux capacity is linked to CVD. We hypothesized that in preeclampsia there would be a disruption of maternal/fetal plasma to efflux cholesterol, as well as differences in the concentrations of both placental sterol 27-hydroxylase (CYP27A1) and apoA1 binding protein (AIBP). Total, HDL-, and ABCA1-mediated cholesterol effluxes were performed with maternal and fetal plasma from women with preeclampsia and normotensive controls (both n = 17). apoA1 and apoE were quantified by chemiluminescence, and 27-hydroxycholesterol (27-OHC) by GC-MS. Immunohistochemistry was used to determine placental expression/localization of CYP27A1, AIBP, apoA1, apoE, and SRB1. Maternal and fetal total and HDL-mediated cholesterol efflux capacities were increased in preeclampsia (by 10-20%), but ABCA1-mediated efflux was decreased (by 20-35%; P preeclampsia. Fetal plasma 27-OHC levels were decreased in preeclamptic samples ( P preeclampsia ( P = 0.04). Placental 27-OHC concentrations were also raised in preeclampsia ( P preeclampsia, to remove cholesterol from cells to limit lipid peroxidation and increase placental angiogenesis. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  6. The antimicrobial activity in vitro of chlorhexidine, a mixture of isothiazolinones ('Kathon' CG) and cetyl trimethyl ammonium bromide (CTAB).

    Science.gov (United States)

    Nicoletti, G; Boghossian, V; Gurevitch, F; Borland, R; Morgenroth, P

    1993-02-01

    Chlorehexidine, two 4% chlorhexidine antiseptic handwashes ('Bioprep' and 'Hibiclens'), cetyl trimethyl ammonium bromide (CTAB) and isothiazolinones ('Kathon') were tested against Staphylococcus aureus, Micrococcus luteus, Escherichia coli, Serratia marcescens, Pseudomonas aeruginosa, Proteus vulgaris and Candida albicans. The activities measured were the minimum inhibitory concentration (MIC), minimum microbicidal concentration (MMC), rate of kill in water and broth, effect of organic soil, the development of microbial resistance on continuous exposure and agent bioavailability in media and formulation. 'Kathon' was the most active microbistatic agent showing maximal activity at low concentration, least inactivation by organic soil and media components and the lowest level of development of bacterial resistance. It was synergistic with chlorhexidine against S. marcescens and P. aeruginosa. Media, formulation components and organic soil affected the performance of chlorhexidine and CTAB. Chlorhexidine was more broadly active than CTAB but showed a greater reduction in activity in the presence of soil and engendered a greater level of bacterial resistance. It was more rapidly bactericidal to P. aeruginosa and S. marcescens than to S. aureus. Stable resistance to chlorhexidine and CTAB was developed by P. aeruginosa and S. marcescens, the latter showing the higher level of resistance. Chlorhexidine-resistant strains were also resistant to CTAB. The antiseptic formulations were more rapidly bactericidal than chlorhexidine alone but were otherwise of comparable activity. Mixtures of disinfectants, in particular a combination of chlorhexidine and a preservative level of 'Kathon', were more active than single disinfectants. The importance of standardization of media and test conditions and the use of chemically defined media for accurate and reproducible in-vitro testing of disinfectant activity is emphasized. Disinfection kinetics, expressed as time-kill curves, log

  7. Bromate formation in bromide-containing water through the cobalt-mediated activation of peroxymonosulfate.

    Science.gov (United States)

    Li, Zhaobing; Chen, Zhi; Xiang, Yingying; Ling, Li; Fang, Jingyun; Shang, Chii; Dionysiou, Dionysios D

    2015-10-15

    Bromate formation in bromide-containing water through the cobalt (Co)-mediated activation of peroxymonosulfate (PMS) was investigated. Increasing the PMS dosage and the cobalt dosage increased the formation of bromate and bromate yields of up to 100% were recorded under the test conditions. The bromate yield increased to a maximum as the pH rose from 2.7 to 6 before decreasing by over 90% as the pH rose further from 6 to above 9. The bromate formation is a two-step process involving free bromine as a key intermediate and bromate as the final product. In the first step, apart from the known oxidation of bromide to free bromine and of free bromine to bromate by sulfate radicals (SO4(-)), Co(III) produced from the oxidation of Co(II) by PMS and SO4(-) also oxidizes bromide to free bromine. The contribution of Co(III) to the bromate formation was verified with the addition of methanol and EDTA, a radical scavenger and a Co(III) ligand, respectively. In the presence of methanol, free bromine formation increased with increasing Co(II) dosage but no bromate was detected, indicating that Co(III) oxidized bromide to form free bromine but not bromate. In the presence of both EDTA and methanol, no free bromine or bromate was detected, as Co(III) was stabilized by EDTA to form the Co(III)EDTA(-) complex, which could not oxidize bromide. Mathematical simulation further suggested that Co(III) outweighed SO4(-) to oxidize bromide to free bromine. On the other hand, SO4(-) is essential for the oxidation of free bromine to bromate in the second step. In real water, the presence of NOM significantly decreased the bromate formation but caused the brominated organic DBP formation with high quantity. This is the first study to demonstrate the significant bromate formation in the Co/PMS system and the substantial contribution of Co(III) to the formation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Comparison of phenobarbital with bromide as a first-choice antiepileptic drug for treatment of epilepsy in dogs.

    Science.gov (United States)

    Boothe, Dawn Merton; Dewey, Curtis; Carpenter, David Mark

    2012-05-01

    To compare efficacy and safety of treatment with phenobarbital or bromide as the first-choice antiepileptic drug (AED) in dogs. Double-blinded, randomized, parallel, clinical trial. 46 AED-naïve dogs with naturally occurring epilepsy. Study inclusion was based on age, history, findings on physical and neurologic examinations, and clinicopathologic test results. For either phenobarbital treatment (21 dogs) or bromide treatment (25), a 7-day loading dose period was initiated along with a maintenance dose, which was adjusted on the basis of monthly monitoring. Efficacy and safety outcomes were compared between times (baseline and study end [generally 6 months]) and between drugs. Phenobarbital treatment resulted in eradication of seizures (17/20 [85%]) significantly more often than did bromide (12/23 [52%]); phenobarbital treatment also resulted in a greater percentage decrease in seizure duration (88 ± 34%), compared with bromide (49 ± 75%). Seizure activity worsened in 3 bromide-treated dogs only. In dogs with seizure eradication, mean ± SD serum phenobarbital concentration was 25 ± 6 μg/mL (phenobarbital dosage, 4.1 ± 1.1 mg/kg [1.9 ± 0.5 mg/lb], p.o., q 12 h) and mean serum bromide concentration was 1.8 ± 0.6 mg/mL (bromide dosage, 31 ± 11 mg/kg [14 ± 5 mg/lb], p.o., q 12 h). Ataxia, lethargy, and polydipsia were greater at 1 month for phenobarbital-treated dogs; vomiting was greater for bromide-treated dogs at 1 month and study end. Both phenobarbital and bromide were reasonable first-choice AEDs for dogs, but phenobarbital was more effective and better tolerated during the first 6 months of treatment.

  9. Kinetic study on anaerobic oxidation of methane coupled to denitrification.

    Science.gov (United States)

    Yu, Hou; Kashima, Hiroyuki; Regan, John M; Hussain, Abid; Elbeshbishy, Elsayed; Lee, Hyung-Sool

    2017-09-01

    Monod kinetic parameters provide information required for kinetic analysis of anaerobic oxidation of methane coupled to denitrification (AOM-D). This information is critical for engineering AOM-D processes in wastewater treatment facilities. We first experimentally determined Monod kinetic parameters for an AOM-D enriched culture and obtained the following values: maximum specific growth rate (μmax) 0.121/d, maximum substrate-utilization rate (qmax) 28.8mmol CH4/g cells-d, half maximum-rate substrate concentration (Ks) 83μΜ CH4, growth yield (Y) 4.76gcells/mol CH4, decay coefficient (b) 0.031/d, and threshold substrate concentration (Smin) 28.8μM CH4. Clone library analysis of 16S rRNA and mcrA gene fragments suggested that AOM-D reactions might have occurred via the syntrophic interaction between denitrifying bacteria (e.g., Ignavibacterium, Acidovorax, and Pseudomonas spp.) and hydrogenotrophic methanogens (Methanobacterium spp.), supporting reverse methanogenesis-dependent AOM-D in our culture. High μmax and qmax, and low Ks for the AOM-D enrichment imply that AOM-D could play a significant role in mitigating atmospheric methane efflux. In addition, these high kinetic features suggest that engineered AOM-D systems may provide a sustainable alternative to nitrogen removal in wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Atmospheric volatilization of methyl bromide, 1,3-dichloropropene, and propargyl bromide through two plastic films: transfer coefficient and temperature effect

    Science.gov (United States)

    Wang, D.; Yates, S. R.; Gan, J.; Knuteson, J. A.

    Atmospheric emission of methyl bromide (MeBr) and its potential alternative chemicals such as 1,3-dichloropropene (1,3-D) and propargyl bromide (PrBr) can contribute to air pollution and ozone depletion (for MeBr). One of the main sources of these chemicals is from agricultural soil fumigation. To understand the volatilization dynamics, emission of MeBr, 1,3-D, and PrBr through a polyethylene-based high-barrier film (HBF) and a virtually impermeable film (VIF) was measured using an air flow and sampling system that produced >90% mass balance. The experiment was conducted outdoors and was subjected to ambient daily temperature variations. The HBF film was found to be very permeable to 1,3-D and PrBr, but somewhat less permeable to MeBr. The VIF film was very impermeable to 1,3-D, PrBr, or MeBr. Measured volatilization flux, in general, exhibited strong diurnal variations which were controlled by film temperature. Unlike the HBF film, a time lag (˜12 h) was observed between high-temperatures and high-emission flux values for the VIF film. An impermeable film may be used as an effective means of controlling the atmospheric emission of MeBr and its alternative chemicals.

  11. Uptake, efflux, and mass transfer coefficient of fluorescent PAMAM dendrimers into pancreatic cancer cells.

    Science.gov (United States)

    Opitz, Armin W; Czymmek, Kirk J; Wickstrom, Eric; Wagner, Norman J

    2013-02-01

    Targeted delivery of imaging agents to cells can be optimized with the understanding of uptake and efflux rates. Cellular uptake of macromolecules is studied frequently with fluorescent probes. We hypothesized that the internalization and efflux of fluorescently labeled macromolecules into and out of mammalian cells could be quantified by confocal microscopy to determine the rate of uptake and efflux, from which the mass transfer coefficient is calculated. The cellular influx and efflux of a third generation poly(amido amine) (PAMAM) dendrimer labeled with an Alexa Fluor 555 dye was measured in Capan-1 pancreatic cancer cells using confocal fluorescence microscopy. The Capan-1 cells were also labeled with 5-chloromethylfluorescein diacetate (CMFDA) green cell tracker dye to delineate cellular boundaries. A dilution curve of the fluorescently labeled PAMAM dendrimer enabled quantification of the concentration of dendrimer in the cell. A simple mass transfer model described the uptake and efflux behavior of the PAMAM dendrimer. The effective mass transfer coefficient was found to be 0.054±0.043μm/min, which corresponds to a rate constant of 0.035±0.023min(-1) for uptake of the PAMAM dendrimer into the Capan-1 cells. The effective mass transfer coefficient was shown to predict the efflux behavior of the PAMAM dendrimer from the cell if the fraction of labeled dendrimer undergoing non-specific binding is accounted for. This work introduces a novel method to quantify the mass transfer behavior of fluorescently labeled macromolecules into mammalian cells. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Distribution and expression of the Ade multidrug efflux systems in Acinetobacter baumannii clinical isolates.

    Science.gov (United States)

    Pagdepanichkit, Sirawit; Tribuddharat, Chanwit; Chuanchuen, Rungtip

    2016-09-01

    One hundred Acinetobacter baumannii clinical isolates were examined for inhibitory effect of reserpine and carbonyl cyanide m-chlorophenylhydrazone (CCCP) on the antimicrobial susceptibility and expression of 4 resistant-nodulation-cell division (RND)-type multidrug efflux systems, including AdeABC, AdeDE, AdeIJK, and AdeFGH, using RT-PCR. Ten A. baumannii isolates expressing AdeABC, AdeIJK, or AdeFGH were randomly selected for determination of transcription level and regulatory mutations. While all the isolates were resistant to multiple drugs, the reserpine and CCCP experiment showed that the multidrug resistance phenotype in most A. baumannii isolates was associated with efflux pumps. Most isolates expressed at least one of the RND-type efflux pumps tested (97%). AdeIJK expression was most common (97%), but none of the isolates produced AdeDE. Fifty-two percent of the A. baumannii isolates simultaneously produced up to 3 RND-type efflux systems (i.e., AdeABC, AdeFGH, and AdeIJK). No good correlation between the expression of RND-type efflux pumps and the type of antimicrobial resistance was observed. Overexpression of AdeABC, AdeIJK, and AdeFGH was not always related to the presence of mutations in their corresponding regulatory genes. This study highlights (i) the universal presence of the RND-type efflux pumps with variable levels of expression level among the A. baumannii in this collection and (ii) the complexity of their regulation of expression.

  13. Crystal structure of the CusBA heavy-metal efflux complex of Escherichia coli.

    Science.gov (United States)

    Su, Chih-Chia; Long, Feng; Zimmermann, Michael T; Rajashankar, Kanagalaghatta R; Jernigan, Robert L; Yu, Edward W

    2011-02-24

    Gram-negative bacteria, such as Escherichia coli, expel toxic chemicals through tripartite efflux pumps that span both the inner and outer membrane. The three parts are an inner membrane, substrate-binding transporter; a membrane fusion protein; and an outer-membrane-anchored channel. The fusion protein connects the transporter to the channel within the periplasmic space. A crystallographic model of this tripartite efflux complex has been unavailable because co-crystallization of the various components of the system has proven to be extremely difficult. We previously described the crystal structures of both the inner membrane transporter CusA and the membrane fusion protein CusB of the CusCBA efflux system of E. coli. Here we report the co-crystal structure of the CusBA efflux complex, showing that the transporter (or pump) CusA, which is present as a trimer, interacts with six CusB protomers and that the periplasmic domain of CusA is involved in these interactions. The six CusB molecules seem to form a continuous channel. The affinity of the CusA and CusB interaction was found to be in the micromolar range. Finally, we have predicted a three-dimensional structure for the trimeric CusC outer membrane channel and developed a model of the tripartite efflux assemblage. This CusC(3)-CusB(6)-CusA(3) model shows a 750-kilodalton efflux complex that spans the entire bacterial cell envelope and exports Cu I and Ag I ions.

  14. Facile Synthesis of Heterocycles via 2-Picolinium Bromide and Antimicrobial Activities of the Products

    Directory of Open Access Journals (Sweden)

    Elham S. Darwish

    2008-05-01

    Full Text Available The 2-picolinium N-ylide 4, generated in situ from the N-acylmethyl-2-picolinium bromide 3, underwent cycloaddition to N-phenylmaleimide or carbon disulfideto give the corresponding cycloadducts 6 and 8, respectively similar reactions ofcompound 3 with some electron-deficient alkenes in the presence of MnO2 yielded theproducts 11 and 12. In addition, reaction of 4 with arylidene cyanothioacetamide andmalononitrile derivatives afforded the thiophene and aniline derivatives 15 and 17,respectively. Heating of picolinium bromide 3 with triethylamine in benzene furnished 2-(2-thienylindolizine (18. The structures of the isolated products were confirmed byelemental analysis as well as by 1H- and 13C-NMR, IR, and MS data. Both thestereochemistry and the regioselectivity of the studied reactions are discussed. Thebiological activity of the newly synthesized compounds was examined and showedpromising results.

  15. Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters.

    Science.gov (United States)

    Ivey, Chris D; Ingersoll, Chris G

    2016-10-01

    Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response of H. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L. Environ Toxicol Chem 2016;35:2425-2429. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

  16. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    Science.gov (United States)

    Kaji, Masao; Furukawa, Masahiro; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    A theoretical prediction model of the boiling heat transfer coefficient in the subcooled region for water and lithium bromide aqueous solution flowing in a rectangular channel is proposed. In the present heat transfer model, a heat flux is assumed to consist of both the forced convective and the boiling effect components. The forced convective component is evaluated from the empirical correlation of convective heat transfer coefficient for single-phase flow considering the effect of increase of liquid velocity due to net vapor generation. Empirical correlations for determining the heat flux due to the boiling effect and the quality at the onset point of net vapor generation are obtained from the data presented in the first report1). Agreement between the present theoretical prediction and the experimental data is satisfactorily good both for water and lithium bromide aqueous solution.

  17. Thermodynamic Properties of Hydrogen + Tetra-n-Butyl Ammonium Bromide Semi-Clathrate Hydrate

    Directory of Open Access Journals (Sweden)

    Shunsuke Hashimoto

    2010-01-01

    Full Text Available Thermodynamic stability and hydrogen occupancy on the hydrogen + tetra-n-butyl ammonium bromide semi-clathrate hydrate were investigated by means of Raman spectroscopic and phase equilibrium measurements under the three-phase equilibrium condition. The structure of mixed gas hydrates changes from tetragonal to another structure around 95 MPa and 292 K depending on surrounding hydrogen fugacity. The occupied amount of hydrogen in the semi-clathrate hydrate increases significantly associated with the structural transition. Tetra-n-butyl ammonium bromide semi-clathrate hydrates can absorb hydrogen molecules by a pressure-swing without destroying the hydrogen bonds of hydrate cages at 15 MPa or over.

  18. Preparation and optical characteristics of layered perovskite-type lead-bromide-incorporated azobenzene chromophores

    Science.gov (United States)

    Sasai, Ryo; Shinomura, Hisashi

    2013-02-01

    Lead bromide-based layered perovskite powders with azobenzene derivatives were prepared by a homogeneous precipitation method. From the diffuse reflectance (DR) and photoluminescence (PL) spectra of the hybrid powder materials, the present hybrids exhibited sharp absorption and PL peaks originating from excitons produced in the PbBr42- layer. When the present hybrid powder was irradiated with UV light at 350 nm, the absorption band from the trans-azobenzene chromophore, observed around 350 nm, decreased, while the absorption band from the cis-azobenzene chromophore, observed around 450 nm, increased. These results indicate that azobenzene chromophores in the present hybrid materials exhibit reversible photoisomerization. Moreover, it was found that the PL intensity from the exciton also varied due to photoisomerization of the azobenzene chromophores in the present hybrid. Thus, for the first time we succeeded in preparing the azobenzene derivative lead-bromide-based layered perovskite with photochromism before and after UV light irradiation.

  19. Effect of Concentration on Evaporation Rate for Lithium Bromide Aqueous Solution in a Falling Film Heater

    Science.gov (United States)

    Matsuda, Akira; Ide, Tetsuo

    Experiments on evaporation for lithium bromide aqueous solution (0-55 wt% LiBr) were made in Summary a externally heated wetted-wall column under reduced pressures. The evaporation rates of 5 and 8 wt% LiBr-water solutions were similar to those of water. The evaporation rates, however, owered with further increase of the concentration of LiBr, and at low feed rates the evaporation rates lowered with decrease of the feed rate because the temperature of the falling film rose. On the other hand, at high feed rates the evaporation rates lowered with increase of feed rates because the heat transfer coefficients of the falling film decreased. Therefore, a maximum evaporation rate existed and it was supposed that there is the optimum feed rate. The experimental data agreed with the values that were calculated numerically based on the unidirectional model that lithium bromide didn't move through falling film.

  20. Pd-catalyzed Heck reactions of aryl bromides with 1,2-diarylethenes

    Energy Technology Data Exchange (ETDEWEB)

    Limberger, Jones; Poersch, Silvia; Monteiro, Adriano L., E-mail: adriano.monteiro@ufrgs.b [Universidade Federal do Rio Grande do Sul (LCM/UFRGS), Porto Alegre, RS (Brazil). Lab. of Molecular Catalysis

    2011-07-01

    A catalytic system composed of Pd(OAc){sub 2} and P(o-tol){sub 3} was found to be effective for the Heck reaction of aryl bromides with diarylethylenes. Using K{sub 2}CO{sub 3} as a base and DMF as a solvent, trisubstituted olefins were obtained in good to excellent yields. Aryl bromides containing an electron-withdrawing group in para position were less reactive for the Heck coupling reaction and gave substantial amount of homocoupling by-product suggesting that oxidative addition is not the rate-determining step. Electron withdrawing group substituent in the para position of stilbene affects the regioselectivity of the reaction. In this case, the phenyl group from the Ph-Pd complex migrates preferentially to the same carbon of the double bond to which the phenyl is bonded. Finally, a one pot sequential double Heck arylation of styrene was performed, giving trisubstituted olefin with an overall yield of 73%. (author)

  1. Evaluation of alternatives to methyl bromide in melon crops in Guatemala.

    Science.gov (United States)

    Díaz-Pérez, M; Camacho-Ferre, F; Diánez-Martínez, F; De Cara-García, M; Tello-Marquina, J C

    2009-02-01

    The monoculture of melon in Guatemala has caused the massive appearance of plants with an analogous syndrome for the well-known disease commonly called melon collapse, or vine decline, causing significant losses in crops. Methyl bromide is commonly used to sterilize soil prior to planting in Guatemala, but it must be phased out by 2015. The objective of this study was to evaluate the technique of grafting melon onto hybrids of Cucurbita (Cucurbita maxima x Cucurbita moschata), as an alternative to using soil disinfectants (such as Metam sodium, 1,3-dichloropropene, and methyl bromide) for the control of collapse. The results suggested that both soil disinfection and grafting were not necessary in these locations, since there were no statistical differences in terms of yields between the treatments and the untreated control. Furthermore, these results demonstrate that decisions to disinfect the soil must be based on the firm identification of the causal agents, in addition to preliminary assessments of yield losses.

  2. Formation pathways of brominated products from benzophenone-4 chlorination in the presence of bromide ions.

    Science.gov (United States)

    Xiao, Ming; Wei, Dongbin; Li, Liping; Liu, Qi; Zhao, Huimin; Du, Yuguo

    2014-12-01

    The brominated products, formed in chlorination treatment of benzophenone-4 in the presence of bromide ions, were identified, and the formation pathways were proposed. Under disinfection conditions, benzophenone-4 would undertake electrophilic substitution generating mono- or di-halogenated products, which would be oxidized to esters and further hydrolyzed to phenol derivatives. The generated catechol intermediate would be transformed into furan-like heterocyclic product. The product species were pH-dependent, while benzophenone-4 elimination was chlorine dose-dependent. When the chlorination treatment was performed on ambient water spiked with benzophenone-4 and bromide ions, most of brominated byproducts could be detected, and the acute toxicity significantly increased as well. Copyright © 2014. Published by Elsevier B.V.

  3. A novel model-based approach for dose determination of glycopyrronium bromide in COPD

    Directory of Open Access Journals (Sweden)

    Arievich Helen

    2012-12-01

    Full Text Available Abstract Background Glycopyrronium bromide (NVA237 is an inhaled long-acting muscarinic antagonist in development for treatment of COPD. This study compared the efficacy and safety of once-daily (OD and twice-daily (BID glycopyrronium bromide regimens, using a novel model-based approach, in patients with moderate-to-severe COPD. Methods Double-blind, randomized, dose-finding trial with an eight-treatment, two-period, balanced incomplete block design. Patients (smoking history ≥10 pack-years, post-bronchodilator FEV1 ≥30% and 1/FVC 1 at Day 28. Results 385 patients (mean age 61.2 years; mean post-bronchodilator FEV1 53% predicted were randomized; 88.6% completed. All OD and BID dosing regimens produced dose-dependent bronchodilation; at Day 28, increases in mean trough FEV1 versus placebo were statistically significant for all regimens, ranging from 51 mL (glycopyrronium bromide 12.5 μg OD to 160 mL (glycopyrronium bromide 50 μg BID. Pharmacodynamic steady-state was reached by Day 7. There was a small separation (≤37 mL between BID and OD dose–response curves for mean trough FEV1 at steady-state in favour of BID dosing. Over 24 hours, separation between OD and BID regimens was even smaller (FEV1 AUC0-24h maximum difference for equivalent daily dose regimens: 8 mL. Dose–response results for FEV1 at 12 hours, FEV1 AUC0-12h and FEV1 AUC0-4h at steady-state showed OD regimens provided greater improvement over placebo than BID regimens for total daily doses of 25 μg, 50 μg and 100 μg, while the reverse was true for OD versus BID regimens from 12–24 hours. The 12.5 μg BID dose produced a marginally higher improvement in trough FEV1 versus placebo than 50 μg OD, however, the response at 12 hours over placebo was suboptimal (74 mL. Glycopyrronium bromide was safe and well tolerated at all doses. Conclusions Glycopyrronium bromide 50 μg OD provides significant bronchodilation over a 24 hour period

  4. Association between increased arterial-wall thickness and impairment in ABCA1-driven cholesterol efflux : an observational study

    NARCIS (Netherlands)

    van Dam, MJ; de Groot, E; Clee, SM; Hovingh, GK; Roelants, R; Brooks-Wilson, A; Zwinderman, AH; Smit, AJ; Smelt, A.H.; Groen, AK; Hayden, MR; Kastelein, JJP

    2002-01-01

    Background Decreased concentrations of HDL cholesterol are associated with increased cardiovascular risk. These concentrations are directly related to cholesterol efflux from cells-the first step and a key process in reverse cholesterol transport. Cholesterol efflux is mediated by the ATP-binding

  5. Contribution of vesicular and cytosolic dopamine to the increased striatal dopamine efflux elicited by intrastriatal injection of SKF38393.

    NARCIS (Netherlands)

    Saigusa, T.; Aono, Y.; Sekino, R.; Uchida, T.; Takada, K.; Oi, Y.; Koshikawa, N.; Cools, A.R.

    2009-01-01

    Like dexamphetamine, SKF38393 induces an increase in striatal dopamine efflux which is insensitive for tetrodotoxin, Ca(2+) independent and prevented by a dopamine transporter inhibitor. The dexamphetamine-induced striatal dopamine efflux originates from both the reserpine-sensitive vesicular

  6. Charging of silver bromide aqueous interface: evaluation of interfacial equilibrium constants from surface potential data.

    Science.gov (United States)

    Preočanin, Tajana; Supljika, Filip; Kallay, Nikola

    2010-06-01

    A single crystal silver bromide electrode (SCr-AgBr) was used to measure the inner surface potential (Ψ(0)) at the silver bromide aqueous electrolyte interface as a function of the activities of Br(-) and Ag(+). Absolute values of the surface potential were calculated from electrode potentials of SCr-AgBr using the value of point of zero charge (pBr(pzc)=6.9 [H.A. Hoyen, R.M. Cole, J. Colloid Interface Sci. 41 (1972) 93.]) as the value of point of zero potential. Measurements were performed in potassium nitrate aqueous solutions. The Ψ(0)(pBr) function was linear and slightly dependent on the ionic strength. The reduction values of the slope with respect to the Nernst equation, expressed by the α coefficient, were 0.880,0.935, and 0.950 at ionic strengths of 10(-4), 10(-3), and 10(-2) mol dm(-3), respectively. The results were successfully interpreted by employing the surface complexation model, developed originally for metal oxides and adapted for silver halides. The thermodynamic ("intrinsic") equilibrium constants for binding of bromide (K(n)(∘)) and silver (K(p)(∘)) ions on the corresponding sites at the silver bromide surface were evaluated as lgK(n)(∘)=3.98; lgK(p)(∘)=2.48. Symmetrical counterion surface association was assumed and equilibrium constants were obtained as lgK(NO(3)(-))(∘)=lgK(K(+))(∘)=4.30. Copyright © 2010 Elsevier Inc. All rights reserved.

  7. Synthesis of Dimethyl Aryl Acylsulfonium Bromides from Aryl Methyl Ketones in a DMSO-HBr System

    Directory of Open Access Journals (Sweden)

    Zhiling Cao

    2013-12-01

    Full Text Available A new, simplified method for the synthesis of dimethyl aryl acylsulfonium salts has been developed. A series of dimethyl aryl acylsulfonium bromides were prepared by the reaction of aryl methyl ketones with hydrobromic acid and dimethylsulfoxide (DMSO. This sulfonium salt confirms that bromine production and the bromination reaction take place in the DMSO-HBr oxidation system. What’s more, it is also a key intermediate for the synthesis of arylglyoxals.

  8. Synthesis of dimethyl aryl acylsulfonium bromides from aryl methyl ketones in a DMSO-HBr system.

    Science.gov (United States)

    Cao, Zhiling; Shi, Dahua; Qu, Yingying; Tao, Chuanzhou; Liu, Weiwei; Yao, Guowei

    2013-12-16

    A new, simplified method for the synthesis of dimethyl aryl acylsulfonium salts has been developed. A series of dimethyl aryl acylsulfonium bromides were prepared by the reaction of aryl methyl ketones with hydrobromic acid and dimethylsulfoxide (DMSO). This sulfonium salt confirms that bromine production and the bromination reaction take place in the DMSO-HBr oxidation system. What's more, it is also a key intermediate for the synthesis of arylglyoxals.

  9. 1-Bromomethyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide

    Directory of Open Access Journals (Sweden)

    Aaron D. Finke

    2010-02-01

    Full Text Available The title compound, C7H14BrN2+·Br−, was prepared by nucleophilic substitution of DABCO (systematic name: 1,4-diazabicyclo[2.2.2]octane with dibromomethane in acetone. The structure features Br...H close contacts (2.79 and 2.90 Å as well as a weak bromine–bromide interaction [3.6625 (6 Å].

  10. Replacing conventional carbon nucleophiles with electrophiles: nickel-catalyzed reductive alkylation of aryl bromides and chlorides.

    Science.gov (United States)

    Everson, Daniel A; Jones, Brittany A; Weix, Daniel J

    2012-04-11

    A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons. Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields. Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes. The protocols are highly functional-group tolerant (-OH, -NHTs, -OAc, -OTs, -OTf, -COMe, -NHBoc, -NHCbz, -CN, -SO(2)Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture. The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki-Miyaura, Stille, and Hiyama-Denmark reactions. Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R-X) and no reaction at the nucleophilic carbon (R-[M]) for organoboron (-Bpin), organotin (-SnMe(3)), and organosilicon (-SiMe(2)OH) containing organic halides (X-R-[M]). A Hammett study showed a linear correlation of σ and σ(-) parameters with the relative rate of reaction of substituted aryl bromides with bromoalkanes. The small ρ values for these correlations (1.2-1.7) indicate that oxidative addition of the bromoarene is not the turnover-frequency determining step. The rate of reaction has a positive dependence on the concentration of alkyl bromide and catalyst, no dependence upon the amount of zinc (reducing agent), and an inverse dependence upon aryl halide concentration. These results and studies with an organic reductant (TDAE) argue against the intermediacy of organozinc reagents. © 2012 American Chemical Society

  11. Factors Affecting the Stability and Performance of Ipratropium Bromide; Fenoterol Hydrobromide Pressurized-Metered Dose Inhalers

    OpenAIRE

    Ninbovorl, Jenjira; Sawatdee, Somchai; Srichana, Teerapol

    2013-01-01

    The aim of the study was to investigate the factors affecting the stability and performance of ipratropium bromide and fenoterol hydrobromide in a pressurized-metered dose inhaler (pMDI). A factorial design was applied to investigate the effects of three parameters (propellant, water, and ethanol) on the performance of 27 designed formulations of a solution-based pMDI. The formulations that contained a hydrofluoroalkane (HFA) propellant lower than 72% v/v and an ethanol concentration higher t...

  12. Adsorption of Indigo Carmine Dye Using Cetyltrimethylammonium Bromide (CTAB) Surfactant Modified Zeolite

    OpenAIRE

    Fauziyah, Nurul; Sriatun, Sriatun; Pardoyo, Pardoyo

    2015-01-01

    Research of indigo carmine dye adsorption using natural zeolite modified by cetyltrimethylammonium bromide (CTAB) surfactant has been done. The purpose of this study was to modify the natural zeolite using CTAB surfactant and to determine its ability on the adsorption of indigo carmine dye. The stages of the study included the activation of zeolites, modifying zeolites using CTAB surfactant and adsorption test of indigo carmine dye. The results showed that the zeolites could be modified by CT...

  13. Mechanism of HERG potassium channel inhibition by tetra-n-octylammonium bromide and benzethonium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Long, Yan; Lin, Zuoxian [Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530 (China); Xia, Menghang; Zheng, Wei [National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892 (United States); Li, Zhiyuan, E-mail: li_zhiyuan@gibh.ac.cn [Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530 (China)

    2013-03-01

    Tetra-n-octylammonium bromide and benzethonium chloride are synthetic quaternary ammonium salts that are widely used in hospitals and industries for the disinfection and surface treatment and as the preservative agent. Recently, the activities of HERG channel inhibition by these compounds have been found to have potential risks to induce the long QT syndrome and cardiac arrhythmia, although the mechanism of action is still elusive. This study was conducted to investigate the mechanism of HERG channel inhibition by these compounds by using whole-cell patch clamp experiments in a CHO cell line stably expressing HERG channels. Tetra-n-octylammonium bromide and benzethonium chloride exhibited concentration-dependent inhibitions of HERG channel currents with IC{sub 50} values of 4 nM and 17 nM, respectively, which were also voltage-dependent and use-dependent. Both compounds shifted the channel activation I–V curves in a hyperpolarized direction for 10–15 mV and accelerated channel activation and inactivation processes by 2-fold. In addition, tetra-n-octylammonium bromide shifted the inactivation I–V curve in a hyperpolarized direction for 24.4 mV and slowed the rate of channel deactivation by 2-fold, whereas benzethonium chloride did not. The results indicate that tetra-n-octylammonium bromide and benzethonium chloride are open-channel blockers that inhibit HERG channels in the voltage-dependent, use-dependent and state-dependent manners. - Highlights: ► Tetra-n-octylammonium and benzethonium are potent HERG channel inhibitors. ► Channel activation and inactivation processes are accelerated by the two compounds. ► Both compounds are the open-channel blockers to HERG channels. ► HERG channel inhibition by both compounds is use-, voltage- and state dependent. ► The in vivo risk of QT prolongation needs to be studied for the two compounds.

  14. Managing Weeds and Soilborne Pests with Fumigant and Non-Fumigant Alternatives to Methyl Bromide

    OpenAIRE

    McAvoy, Theodore Porter

    2012-01-01

    Methyl bromide (MBr) was widely used as a soil fumigant to manage soilborne pests in plasticulture vegetable production; however, it has been banned by the United Nations Environment Programme. Alternatives to MBr must be implemented to sustain fresh market tomato productivity. Possible MBr alternatives include new fumigant compounds, improved plastic mulch, and grafting. Methyl iodide (MeI) and dimethyl disulfide (DMDS) were tested as fumigant alternatives to MBr for the control of yellow...

  15. 1-(2-Bromoethyl-1,4-diazoniabicyclo[2.2.2]octane bromide tetrafluoroborate

    Directory of Open Access Journals (Sweden)

    Jing-mei Xiao

    2010-06-01

    Full Text Available In the crystal of the title compound, C8H17BrN22+·Br−·BF4−, a weak intermolecular N—H...Br hydrogen bond is observed between the cation and the bromide anion. A two-part disorder model was applied to the BF4− anion with a refined major–minor occupancy ratio of 0.837 (14:0.163 (14.

  16. Flash photolytic generation and study of p-quinone methide in aqueous solution. An estimate of rate and equilibrium constants for heterolysis of the carbon-bromine bond in p-hydroxybenzyl bromide.

    Science.gov (United States)

    Chiang, Y; Kresge, A J; Zhu, Y

    2002-06-05

    Flash photolysis of p-hydroxybenzyl acetate in aqueous perchloric acid solution and formic acid, acetic acid, biphosphate ion, and tris(hydroxymethyl)methylammonium ion buffers produced p-quinone methide as a short-lived species that underwent hydration to p-hydroxybenzyl alcohol in hydronium ion catalyzed (k(H(+)) = 5.28 x 10(4) M(-1) s(-1)) and uncatalyzed (k(uc) = 3.33 s(-1)) processes. The inverse nature of the solvent isotope effect on the hydronium ion-catalyzed reaction, k(H(+))/k(D(+)) = 0.41, indicates that this process occurs by rapid and reversible protonation of the quinone methide on its carbonyl carbon atom, followed by rate-determining capture of the p-hydroxybenzyl carbocation so produced by water, while the magnitude of the rate constant on the uncatalyzed process indicates that this reaction occurs by simple nucleophilic addition of water to the methylene group of the quinone methide. p-Quinone methide also underwent hydronium ion-catalyzed and uncatalyzed nucleophilic addition reactions with chloride ion, bromide ion, thiocyanate ion, and thiourea. The solvent isotope effects on the hydronium ion-catalyzed processes again indicate that these reactions occurred by preequilibrium mechanisms involving a p-hydroxybenzyl carbocation intermediate, and assignment of a diffusion-controlled value to the rate constant for reaction of this cation with thiocyanate ion led to K(SH) = 110 M as the acidity constant of oxygen-protonated p-quinone methide. In a certain perchloric acid concentration range, the bromide ion reaction became biphasic, and least-squares analysis of the kinetic data using a double-exponential function provided k(Br(-)) = 3.8 x 10(8) M(-1) s(-1) as the rate constant for nucleophilic capture of the p-hydroxybenzyl carbocation by bromide ion, k(ionz) = 8.5 x 10(2) s(-1) for ionization of the carbon-bromine bond of p-hydroxybenzyl bromide, and K = 4.5 x 10(5) M(-1) as the equilibrium constant for the carbocation-bromide ion combination

  17. Toxic impact of bromide and iodide on drinking water disinfected with chlorine or chloramines.

    Science.gov (United States)

    Yang, Yang; Komaki, Yukako; Kimura, Susana Y; Hu, Hong-Ying; Wagner, Elizabeth D; Mariñas, Benito J; Plewa, Michael J

    2014-10-21

    Disinfectants inactivate pathogens in source water; however, they also react with organic matter and bromide/iodide to form disinfection byproducts (DBPs). Although only a few DBP classes have been systematically analyzed for toxicity, iodinated and brominated DBPs tend to be the most toxic. The objectives of this research were (1) to determine if monochloramine (NH2Cl) disinfection generated drinking water with less toxicity than water disinfected with free chlorine (HOCl) and (2) to determine the impact of added bromide and iodide in conjunction with HOCl or NH2Cl disinfection on mammalian cell cytotoxicity and genomic DNA damage induction. Water disinfected with chlorine was less cytotoxic but more genotoxic than water disinfected with chloramine. For both disinfectants, the addition of Br(-) and I(-) increased cytotoxicity and genotoxicity with a greater response observed with NH2Cl disinfection. Both cytotoxicity and genotoxicity were highly correlated with TOBr and TOI. However, toxicity was weakly and inversely correlated with TOCl. Thus, the forcing agents for cytotoxicity and genotoxicity were the generation of brominated and iodinated DBPs rather than the formation of chlorinated DBPs. Disinfection practices need careful consideration especially when using source waters containing elevated bromide and iodide.

  18. Serum triglyceride concentration in dogs with epilepsy treated with phenobarbital or with phenobarbital and bromide.

    Science.gov (United States)

    Kluger, Elissa K; Malik, Richard; Ilkin, William J; Snow, David; Sullivan, David R; Govendir, Merran

    2008-10-15

    To compare serum triglyceride concentrations obtained after food had been withheld (i.e., fasting concentrations) in dogs with epilepsy that had been treated long term (> or = 3 months) with phenobarbital or with phenobarbital and potassium bromide with concentrations in healthy control dogs. Cross-sectional study. 57 epileptic dogs that had been treated with phenobarbital (n=28) or with phenobarbital and bromide (29) and 57 healthy, untreated control dogs matched on the basis of age, breed, sex, neuter status, and body condition score. Blood samples were collected after food had been withheld for at least 12 hours, and serum biochemical and lipid concentrations were determined. Oral fat tolerance tests were performed in 15 control dogs and 9 dogs with epilepsy treated with phenobarbital alone. 19 of the 57 (33%) epileptic dogs had fasting serum triglyceride concentrations greater than the upper reference limit. Nine (16%) dogs had a history of pancreatitis, and 5 of the 9 had high fasting serum triglyceride concentrations at the time of the study. A significant relationship was found between body condition score and fasting serum triglyceride concentration in all dogs, but serum triglyceride concentration was not significantly associated with phenobarbital dosage or serum phenobarbital concentration. Results suggested that dogs treated long term with phenobarbital or with phenobarbital and bromide may develop hypertriglyceridemia. Fasting serum triglyceride concentration should be periodically monitored in dogs treated with phenobarbital because hypertriglyceridemia is a risk factor for pancreatitis.

  19. Replacing methyl bromide in annual strawberry production with glucosinolate-containing green manure crops.

    Science.gov (United States)

    Lazzeri, Luca; Baruzzi, Gianluca; Malaguti, Lorena; Antoniacci, Loredana

    2003-09-01

    The use of biocidal green manure crops is an agronomic technique for amending soil with fresh organic matter containing volatile compounds active in controlling some soil-borne pests and diseases. Two new selections of the Brassicaceae family were cultivated, incorporated before planting strawberries and tested as an alternative to fumigation with methyl bromide. Two biocidal green manure crops (Brassica juncea L sel ISCI20, Eruca sativa Mill cv Nemat) containing glucosinolate-myrosinase systems, a conventional green manure (barley), untreated soil and a fumigated control were evaluated during two seasons. The effect of these soil management systems on subsequent strawberry performance was evaluated by monitoring yield and plant growth parameters. In both years, biocidal plant green manure treatments led to a fruit yield lower than with methyl bromide, but higher than with conventional green manure or untreated soil. These results confirm the good prospects for biocidal green manures, not only as an environmentally friendly alternative to methyl bromide in conventional agriculture, but also in organic agriculture as an alternative to conventional green manure crops.

  20. [Treating irritable bowel syndrome by wuling capsule combined pinaverium bromide: a clinical research].

    Science.gov (United States)

    Wu, Xiao-wei; Hou, Yu; Ji, Hong-zan; Liang, Ming-ming; Xu, Lian-e; Wang, Fang-yu

    2015-04-01

    To evaluate the efficacy and safety of wuling Capsule combined with Pinaverium Bromide in treatment of irritable bowel syndrome (IBS). Sixty-four IBS patients were randomized into two groups, the treatment group and the control group, 32 in each group. Patients in the treatment group took wuling Capsule (0. 33 g/capsule, 3 times per day) and Pinaverium Bromide (50 mg/tablet, one tablet each time, 3 times per day) , while those in the control group only took Pinaverium Bromide (50 mg/tablet, one tablet each time, 3 times per day). The therapeutic course for all was 6 weeks. IBS symptom score questionnaire, IBS-Quality of Life (IBS-QOL) , Self-Rating Depression Scale (SDS) , and Self-Rating Anxiety Scale (SAS) were assessed before and after treatment. Adverse reactions were also observed. The improvement of abdominal pain, stool frequency, and stool properties, as well as changing rates of integrals were significantly higher in the treatment group than in the control group (P body image, concerns for health, and dietary restriction of IBS-QOL, as well as changing rates of integrals were significantly higher in the treatment group than in the control group (P depression and anxiety of IBS patients with higher safety.

  1. Preparation and optical characteristics of layered perovskite-type lead-bromide-incorporated azobenzene chromophores

    Energy Technology Data Exchange (ETDEWEB)

    Sasai, Ryo, E-mail: rsasai@riko.shimane-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, F3-3(250), Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Shinomura, Hisashi [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, F3-3(250), Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2013-02-15

    Lead bromide-based layered perovskite powders with azobenzene derivatives were prepared by a homogeneous precipitation method. From the diffuse reflectance (DR) and photoluminescence (PL) spectra of the hybrid powder materials, the present hybrids exhibited sharp absorption and PL peaks originating from excitons produced in the PbBr{sub 4}{sup 2-} layer. When the present hybrid powder was irradiated with UV light at 350 nm, the absorption band from the trans-azobenzene chromophore, observed around 350 nm, decreased, while the absorption band from the cis-azobenzene chromophore, observed around 450 nm, increased. These results indicate that azobenzene chromophores in the present hybrid materials exhibit reversible photoisomerization. Moreover, it was found that the PL intensity from the exciton also varied due to photoisomerization of the azobenzene chromophores in the present hybrid. Thus, for the first time we succeeded in preparing the azobenzene derivative lead-bromide-based layered perovskite with photochromism before and after UV light irradiation. - Graphical abstract: For the first time, we succeeded in preparing the azobenzene derivative lead-bromide-based layered perovskite with photochromism before and after UV light irradiation. Highlights: Black-Right-Pointing-Pointer PbBr-based layered perovskite with azobenezene derivatives could be synthesized by a homogeneous precipitation method. Black-Right-Pointing-Pointer Azobenzene derivatives incorporated the present hybrid that exhibited reversible photoisomerization under UV and/or visible light irradiation. Black-Right-Pointing-Pointer PL property of the present hybrid could also be varied by photoisomerization.

  2. Study on Durability and Stability of an Aqueous Electrolyte Solution for Zinc Bromide Hybrid Flow Batteries

    Science.gov (United States)

    Kim, Donghyeon; Jeon, Joonhyeon

    2015-01-01

    Zinc-bromine flow battery using aqueous electrolyte has advantages of cost effective and high energy density, but there still remains a problem improving stability and durability of electrolyte materials during long-time cell operation. This paper focuses on providing a homogeneous aqueous solution for durability and stability of zinc bromide electrolyte. For performance experiments of conventional and proposed electrolyte solutions, detailed cyclic voltammetry (CV) measurements (at a scan rate of 20 mV s-1 in the range of -1.5 V~1.5 V) are carried out for 40 cycles and five kinds of electrolytes containing which has one of additives, such as (conventionally) zinc chloride, potassium chloride, (newly) lithium perchlorate, sodium perchlorate and zeolite-Y are compared with the 2.0 M ZnBr2 electrolyte, respectively. Experimental results show that using the proposed three additives provides higher anodic and cathodic peak current density of electrolytes than using other two conventional additives, and can lead to improved chemical reversibility of zinc bromide electrolyte. Especially, the solution of which the zeolite-Y added, shows enhanced electrochemical stability of zinc bromide electrolyte. Consequently, proposed electrolytes have a significant advantage in comparison with conventional electrolytes on higher stability and durability.

  3. The Effect of Ozonation Process on Bromide-Containing Groundwaters in Bandung Area and Its Surroundings

    Directory of Open Access Journals (Sweden)

    Mindriany Syafila

    2012-11-01

    Full Text Available Disinfection process was applied as the last step of the water treatment to kill pathogenic bacteria in the water. However, according to several studies, the ozonation disinfection process could form undesired by-products. One of the by-products potentially affecting human life is bromate produced from bromide ionic-containing water. This study was carried out to examine the effect of raw water characteristics and pH on bromate formation. Also, the performance of bromate formation for a period of exposure time was analyzed. Raw waters taken from four different areas around Bandung were exposed to ozone introduced to a reactor with a flow rate of 2 L/min. The pH of the raw waters varied from 4, 7 to 10. The results show that there was no evidence of an initial bromide ion concentration, whereas a change in pH value gives a significantly different outcome. In acidic condition (pH of 4 the bromate formation tends to decrease, whereas when the pH value increases to a pH of 10, the bromate formation increases. Therefore, for drinking water with a neutral pH, when bromide ions are detected in the raw water, the drinking water may be toxic due to the presence of bromate.

  4. Managing opioid-induced constipation in advanced illness: focus on methylnaltrexone bromide

    Directory of Open Access Journals (Sweden)

    Katri Elina Clemens

    2010-02-01

    Full Text Available Katri Elina Clemens1,2, Eberhard Klaschik11Department of Science and Research, Centre for Palliative Medicine, University of Bonn, Germany; 2Department of Palliative Medicine and Pain Therapy, Malteser Hospital Bonn/Rhein-Sieg, GermanyAbstract: Constipation is a common symptom in palliative care patients which can generate considerable suffering. There is uncertainty about the choice of treatment options from varying recommendations for management of constipation and a varying clinical practice in palliative care settings. The purpose of the review was to evaluate the current recommendations of therapy guidelines for the management of opioid-induced constipation in palliative care patients with a focus on methylnaltrexone bromide. Recent findings in the literature and related information on the opioid-induced gastrointestinal disorders in patients with advanced illness, as well as information on the opioid-antagonist methylnaltrexone, are discussed. Knowledge of the role of definitions, the causes of constipation and the pathophysiology of opioid-induced constipation must be given high priority in the treatment of patients receiving opioids. Diagnosis and therapy of constipation, therefore, should relate to findings in clinical investigation. Opioid-induced constipation and its adequate treatment is an important issue for patients with advanced illness and also poses therapeutic challenge for clinicians in daily routine. Methylnaltrexone bromide may represent an important therapeutic option for palliative care patients who are suffering from opioid-induced constipation with failure of conventional prophylactic oral laxative treatment.Keywords: opioid-induced constipation, palliative care, opioids, methylnaltrexone bromide

  5. Principles of chemical kinetics

    CERN Document Server

    House, James E

    2007-01-01

    James House's revised Principles of Chemical Kinetics provides a clear and logical description of chemical kinetics in a manner unlike any other book of its kind. Clearly written with detailed derivations, the text allows students to move rapidly from theoretical concepts of rates of reaction to concrete applications. Unlike other texts, House presents a balanced treatment of kinetic reactions in gas, solution, and solid states. The entire text has been revised and includes many new sections and an additional chapter on applications of kinetics. The topics covered include quantitative rela

  6. Introduction to chemical kinetics

    CERN Document Server

    Soustelle, Michel

    2013-01-01

    This book is a progressive presentation of kinetics of the chemical reactions. It provides complete coverage of the domain of chemical kinetics, which is necessary for the various future users in the fields of Chemistry, Physical Chemistry, Materials Science, Chemical Engineering, Macromolecular Chemistry and Combustion. It will help them to understand the most sophisticated knowledge of their future job area. Over 15 chapters, this book present the fundamentals of chemical kinetics, its relations with reaction mechanisms and kinetic properties. Two chapters are then devoted to experimental re

  7. ENTHALPIES OF INTERACTION BETWEEN DIMETHYLDIOCTADECYLAMMONIUM BROMIDE VESICLES IN AQUEOUS-SOLUTION AND EITHER DIPICOLINATE OR SULFATE ANIONS

    NARCIS (Netherlands)

    BLANDAMER, MJ; BRIGGS, B; BUTT, MD; CULLIS, PM; WATERS, M; ENGBERTS, JBFN; HOEKSTRA, D

    1994-01-01

    Injection of small aliquots of dipicolinate anions (sodium salt) into an aqueous solution containing dimethyldioctadecylammonium bromide (DOAB) vesicles is endothermic at 50-degrees-C, becoming first more and then less endothermic. The injection process is effectively athermal for solutions

  8. GREEN CHEMISTRY APPLICATION FOR THE SYNTHESIS OF (1-N-4’-METHOXYBENZYL-1,10-PHENANTHROLINIUM BROMIDE

    Directory of Open Access Journals (Sweden)

    Maulidan Firdaus

    2010-06-01

    Full Text Available A simple, energy-efficient, and relatively quick synthetic procedure for the synthesis of (1-N-4'-methoxybenzyl-1,10-phenanthrolinium bromide, based on green chemistry principles has been carried out. The synthesis was started by solvent-free reduction of p-anisaldehyde with NaBH4 to give 4-methoxybenzyl alcohol in 98% yield to be followed by solvent-free treatment of the resulted alcohol with PBr3 to yield 4-methoxybenzyl bromide (86%. Furthermore, the obtained bromide was reacted with 1,10-phenanthroline in acetone at reflux for 12 h to give the phenanthrolinium salt target in 68% yield.   Keywords: green chemistry, p-anisaldehyde, (1-N-4'-methoxybenzyl-1,10-phenanthrolinium bromide

  9. 78 FR 68021 - Notice of Affirmation of Addition of a Treatment Schedule for Methyl Bromide Fumigation of...

    Science.gov (United States)

    2013-11-13

    ... species, Ceratitis capitata (Mediterranean fruit fly) and Anastrepha fraterculus (South American fruit fly... bromide treatment schedule to mitigate risk from C. capitata and A. fraterculus, as described in the TED...

  10. An experimental investigation of thermo-capillary convection in solution of lithium bromide at non-isothermal absorption

    National Research Council Canada - National Science Library

    Bufetov N. S; Dekhtyar R. A; Ovchinikov V. V

    2016-01-01

    The aim of this work is to obtain new experimental data on the development of thermo-capillary convection in a solution of lithium bromide with non-isothermal absorption of water vapor in a confined vessel...

  11. Ethanol behaviour at the solution-air interface in the presence of Triton X-100 and cetyltrimethylammonium bromide mixture

    National Research Council Canada - National Science Library

    Magdalena Bielawska; Anna Zdziennicka

    2015-01-01

    ...)phenoxypoly(ethylene glycol) (Triton X-100 or TX-100) and cetyltrimethylammonium bromide (CTAB) mixture with ethanol published in our previous paper, the process of ethanol adsorption was investigated...

  12. Detection of water contamination from hydraulic fracturing wastewater: a μPAD for bromide analysis in natural waters.

    Science.gov (United States)

    Loh, Leslie J; Bandara, Gayan C; Weber, Genevieve L; Remcho, Vincent T

    2015-08-21

    Due to the rapid expansion in hydraulic fracturing (fracking), there is a need for robust, portable and specific water analysis techniques. Early detection of contamination is crucial for the prevention of lasting environmental damage. Bromide can potentially function as an early indicator of water contamination by fracking waste, because there is a high concentration of bromide ions in fracking wastewaters. To facilitate this, a microfluidic paper-based analytical device (μPAD) has been developed and optimized for the quantitative colorimetric detection of bromide in water using a smartphone. A paper microfluidic platform offers the advantages of inexpensive fabrication, elimination of unstable wet reagents, portability and high adaptability for widespread distribution. These features make this assay an attractive option for a new field test for on-site determination of bromide.

  13. Methyl Bromide Buffer Zone Distances for Commodity and Structural Fumigation: Active Aeration, Horizontal Stacks, 8 Hours or Less

    Science.gov (United States)

    This document contains buffer zone tables required by certain methyl bromide commodity fumigant product labels that refer to Buffer Zone Lookup Tables located at epa.gov/pesticide-registration/mbcommoditybuffer on the label.

  14. Methyl Bromide Buffer Zone Distances for Commodity and Structural Fumigation: Active Aeration, No Stack, 8 Hours or Less

    Science.gov (United States)

    This document contains buffer zone tables required by certain methyl bromide commodity fumigant product labels that refer to Buffer Zone Lookup Tables located at epa.gov/pesticide-registration/mbcommoditybuffer on the label.

  15. Methyl Bromide Buffer Zone Distances for Commodity and Structural Fumigation: Active Aeration, No Stack, More than 8 Hours

    Science.gov (United States)

    This document contains buffer zone tables required by certain methyl bromide commodity fumigant product labels that refer to Buffer Zone Lookup Tables located at epa.gov/pesticide-registration/mbcommoditybuffer on the label.

  16. Prostate cancer and toxicity from critical use exemptions of methyl bromide: Environmental protection helps protect against human health risks

    Directory of Open Access Journals (Sweden)

    Budnik Lygia T

    2012-01-01

    Full Text Available Abstract Background Although ozone-depleting methyl bromide was destined for phase-out by 2005, it is still widely applied as a consequence of various critical-use-exemptions and mandatory international regulations aiming to restrict the spread of pests and alien species (e.g. in globalized transport and storage. The withdrawal of methyl bromide because of its environmental risk could fortuitously help in the containment of its human toxicity. Methods We performed a systematic review of the literature, including in vitro toxicological and epidemiological studies of occupational and community exposure to the halogenated hydrocarbon pesticide methyl bromide. We focused on toxic (especially chronic or carcinogenic effects from the use of methyl bromide, on biomonitoring data and reference values. Eligible epidemiological studies were subjected to meta-analysis. Results Out of the 542 peer reviewed publications between 1990-2011, we found only 91 referring to toxicity of methyl bromide and 29 using the term "carcinogenic", "neoplastic" or "mutagenic". Several studies provide new additional data pertaining to the mechanistic aspects of methyl bromide toxicity. Few studies have performed a detailed exposure assessment including biomonitoring. Three evaluated epidemiological studies assessed a possible association between cancer and methyl bromide. Overall, exposure to methyl bromide is associated with an increased risk of prostate cancer OR, 1.21; 95% CI (0,98-1.49, P = 0.076. Two epidemiological studies have analyzed environmental, non-occupational exposure to methyl bromide providing evidence for its health risk to the general public. None of the epidemiological studies addressed its use as a fumigant in freight containers, although recent field and case reports do refer to its toxic effects associated with its use in shipping and storage. Conclusions Both the epidemiological evidence and toxicological data suggest a possible link between methyl

  17. Metal accumulation kinetics by the estuarine macroalga, Fucus ceranoides

    Science.gov (United States)

    Varma, Ranjit; Turner, Andrew; Brown, Murray T.; Millward, Geoff E.

    2013-08-01

    The kinetics of Cu, Cd and Pb accumulation by the macroalga, Fucus ceranoides, was studied under simulated estuarine conditions. Accumulation of Cu and Pb proceeded via a pseudo-first-order reaction that was reversible, suggesting desorption or efflux of accumulated metal, with forward rate constants on the order of 0.1 h-1. For both metals, reaction reversibility increased and the equilibrium constant decreased with increasing salinity (from 1 to 33.5) and system response times were <10 h throughout. Accumulation of Cd proceeded via a first-order reaction that was irreversible, suggesting little desorption or efflux of metal, with rate constants that decreased with increasing salinity (from 0.023 to 0.015 h-1) and reaction half-lives ranging from approximately 30-50 h. Inorganic equilibrium speciation calculations suggest that interactions of Cu, Cd and Pb principally involve the respective free ions, but that additional ions (e.g. CdCl+) and biotic processes may also be significant.

  18. THE SINUSOIDAL EFFLUX OF DIBROMOSULFOPHTHALEIN FROM RAT-LIVER IS STIMULATED BY ALBUMIN, LIGANDIN AND FATTY-ACID-BINDING PROTEIN BUT NOT BY OTHER DIBROMOSULFOPHTHALEIN BINDING-PROTEINS

    NARCIS (Netherlands)

    NIJSSEN, HMJ; PIJNING, T; PROOST, JH; MEIJER, DKF; GROOTHUIS, GMM

    Organic anions can be excreted from the liver into the bile or back into the general circulation (sinusoidal efflux). It has previously been shown that the net sinusoidal efflux rate of dibromosulfophthalein from the perfused liver into the perfusate is the result of actual efflux from and reuptake

  19. [Investigation of mutations in transcription factors of efflux pump genes in fluconazole-resistant Candida albicans strains overexpressing the efflux pumps].

    Science.gov (United States)

    Kalkandelen, Kemal Turan; Doluca Dereli, Mine

    2015-10-01

    In recent years, a significant rise in the number of immunocompromised patients have been observed due to cancer chemotherapy, organ transplantation and HIV infection. As a result of this, the frequency of Candida albicans infections in the clinics have been increased. Fluconazole, as being a well tolerated, easy to use drug with minor side effects, is often the first choice antifungal agent for this patient group, both for therapy and prophylaxis. Especially the long-term use of this drug, causes the selection of resistant strains and leads to the development of fluconazole resistance. The most frequently observed resistance mechanism against fluconazole in C.albicans strains is the transportation of the drug out of the cell via efflux pumps. The efflux pumps mainly involved are Cdr1, Cdr2 ve Mdr1 encoded by CDR1, CDR2 and MDR1 genes. It has been shown that, the overexpression of these efflux pump genes was caused by functional mutations in TAC1 and MRR1 genes which encode the transcription factors Tac1p and Mrr1p. This study was aimed to analyze TAC1 and MRR1 genes of 15 C.albicans strains which consist of six fluconazole-susceptible, four susceptible with trailing effect and five fluconazole-resistant isolates plus one resistant strain (DSY292), known to overexpress Mdr1 efflux pump due to P683H mutation in MRR1 gene and one fluconazole-sensitive ATCC 14053 C.albicans strain in terms of mutations with polymerase chain reaction and sequence analysis. Two of the fluconazole-resistant isolates which had overexpression of Cdr1 and Cdr2 pumps known to have overexpression of TAC1 gene, revealed R673Q and A736V mutations. A P683H point mutation, that overexpressed the Mdr1 pump was detected in a fluconazole-resistant strain, which was known to cause MRR1 overexpression. In conclusion, mutations in the transcription factors of the efflux pump genes may play an important role in the resistance against fluconazole among our selected C.albicans strains.

  20. Characterization of zebrafish Abcc4 as an efflux transporter of organochlorine pesticides.

    Science.gov (United States)

    Lu, Xing; Long, Yong; Lin, Li; Sun, Rongze; Zhong, Shan; Cui, Zongbin

    2014-01-01

    DDT and lindane are highly toxic organochlorine pesticides and posing adverse effects on the environment and public health due to their frequent usage in developing countries. ABCC4/MRP4 is an organic anion transporter that mediates cellular efflux of a wide range of exogenous and endogenous compounds such as cyclic nucleotides and anti-cancer drugs; however, it remains unclear whether ABCC4 and its orthologs function in the detoxification of organochlorine pesticides. Here, we demonstrated the roles of zebrafish Abcc4 in cellular efflux of DDT and lindane. Zebrafish abcc4 was maternally expressed in the oocytes and its transcripts were detected in the lens, pancreas, gills, liver, intestine and bladder of developing embryos and in adult tissues examined. DDT and lindane were able to induce the expression of abcc4 gene and overexpression of Abcc4 significantly decreased the cytotoxicity and accumulation of DDT and lindane in LLC-PK1 cells and developing embryos. In contrast, overexpression of an Abcc4-G1188D mutant abolished its transporter function without effects on its substrate binding activity, and sensitized LLC-PK1 cells and developing embryos to toxic pesticides. Moreover, glutathione (GSH) was involved in the efflux of cellular pesticides and ATPase activity in developing embryos can be induced by DDT or lindane. Thus, zebrafish Abcc4 plays crucial roles in cellular efflux of organochlorine pesticides and can be used a potential molecular marker for the monitor of DDT and lindane contamination in the aquatic environment.

  1. Characterization of zebrafish Abcc4 as an efflux transporter of organochlorine pesticides.

    Directory of Open Access Journals (Sweden)

    Xing Lu

    Full Text Available DDT and lindane are highly toxic organochlorine pesticides and posing adverse effects on the environment and public health due to their frequent usage in developing countries. ABCC4/MRP4 is an organic anion transporter that mediates cellular efflux of a wide range of exogenous and endogenous compounds such as cyclic nucleotides and anti-cancer drugs; however, it remains unclear whether ABCC4 and its orthologs function in the detoxification of organochlorine pesticides. Here, we demonstrated the roles of zebrafish Abcc4 in cellular efflux of DDT and lindane. Zebrafish abcc4 was maternally expressed in the oocytes and its transcripts were detected in the lens, pancreas, gills, liver, intestine and bladder of developing embryos and in adult tissues examined. DDT and lindane were able to induce the expression of abcc4 gene and overexpression of Abcc4 significantly decreased the cytotoxicity and accumulation of DDT and lindane in LLC-PK1 cells and developing embryos. In contrast, overexpression of an Abcc4-G1188D mutant abolished its transporter function without effects on its substrate binding activity, and sensitized LLC-PK1 cells and developing embryos to toxic pesticides. Moreover, glutathione (GSH was involved in the efflux of cellular pesticides and ATPase activity in developing embryos can be induced by DDT or lindane. Thus, zebrafish Abcc4 plays crucial roles in cellular efflux of organochlorine pesticides and can be used a potential molecular marker for the monitor of DDT and lindane contamination in the aquatic environment.

  2. Inhibitory effect of PCSK9 on Abca1 protein expression and cholesterol efflux in macrophages.

    Science.gov (United States)

    Adorni, Maria Pia; Cipollari, Eleonora; Favari, Elda; Zanotti, Ilaria; Zimetti, Francesca; Corsini, Alberto; Ricci, Chiara; Bernini, Franco; Ferri, Nicola

    2017-01-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) may have extra-hepatic effects on cholesterol homeostasis of vascular macrophages. In this study, we aimed to investigate PCSK9 role on the anti-atherogenic process of ATP binding cassette transporter A1 (Abca1)-mediated cholesterol efflux. Abca1-mediated cholesterol efflux was evaluated by a radioisotopic technique in mouse peritoneal macrophages (MPM) from wild-type (WT) or LDL receptor knock-out (Ldlr(-/-)) mice exposed to human recombinant PCSK9, in the presence of liver X receptor/retinoid X receptor (LXR/RXR) ligands or acetylated LDL (AcLDL) to stimulate Abca1 expression. Protein and gene expression was evaluated by Western blot and quantitative real time PCR, respectively. PCSK9 inhibited Abca1-mediated cholesterol efflux induced by LXR/RXR agonists in WT MPM (-55%, p cholesterol efflux through a downregulation of Abca1 gene and Abca1 protein expression. This extrahepatic effect may influence relevant steps in the pathogenesis of atherosclerosis, such as foam cell formation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Efflux of hydraulically lifted water from mycorrhizal fungal hyphae during imposed drought

    Science.gov (United States)

    Querejeta, José Ignacio; Allen, Michael F

    2008-01-01

    Apart from improving plant and soil water status during drought, it has been suggested that hydraulic lift (HL) could enhance plant nutrient capture through the flow of mineral nutrients directly from the soil to plant roots, or by maintaining the functioning of mycorrhizal fungi. We evaluated the extent to which the diel cycle of water availability created by HL covaries with the efflux of HL water from the tips of extramatrical (external) mycorrhizal hyphae, and the possible effects on biogeochemical processes. Phenotypic mycorrhizal fungal variables, such as total and live hyphal lengths, were positively correlated with HL efflux from hyphae, soil water potential (dawn), and plant response variables (foliar 15N). The efflux of HL water from hyphae was also correlated with bacterial abundance and soil enzyme activity (P), and the moistening of soil organic matter. Such findings indicate that the efflux of HL water from the external mycorrhizal mycelia may be a complementary explanation for plant nutrient acquisition and survival during drought. PMID:19704776

  4. P-GP efflux pump inhibition potential of common environmental contaminants determined in vitro

    NARCIS (Netherlands)

    Georgantzopoulou, A.; Skoczynska, E.M.; Berg, van den J.H.J.; Brand, W.; Legay, S.; Klein, S.G.; Rietjens, I.; Murk, A.J.

    2014-01-01

    Across different species, cellular efflux pumps such as P-glycoprotein (P-gp; also termed multidrug resistance protein 1 [MDR1]) serve as a first line of defense by transporting toxic xenobiotics out of the cell. This mechanism is also active in aquatic organisms such as mussels, fish, and their

  5. Soil CO2 efflux in three wet meadow ecosystems with different C and N status

    Czech Academy of Sciences Publication Activity Database

    Zemanová, K.; Čížková, Hana; Šantrůčková, H.

    Suppl.S, č. 9 (2008), s. 49-55 ISSN 1585-8553 Institutional research plan: CEZ:AV0Z60870520; CEZ:AV0Z60660521 Keywords : wet meadow * soil CO2 efflux * eutrophication Subject RIV: EH - Ecology, Behaviour Impact factor: 0.898, year: 2008

  6. Cholesterol efflux regulatory protein, Tangier disease and familial high-density lipoprotein deficiency

    NARCIS (Netherlands)

    Hayden, M. R.; Clee, S. M.; Brooks-Wilson, A.; Genest, J.; Attie, A.; Kastelein, J. J.

    2000-01-01

    Cellular cholesterol efflux, by which cholesterol is transported from peripheral cells to HDL acceptor molecules for transport to the liver, is the first step of reverse cholesterol transport. Two genetic disorders, Tangier disease and some cases of familial HDL deficiency, have defects of cellular

  7. Intestinal permeability and P-glycoprotein-mediated efflux transport of ticagrelor in Caco-2 monolayer cells.

    Science.gov (United States)

    Marsousi, Niloufar; Doffey-Lazeyras, Fabienne; Rudaz, Serge; Desmeules, Jules A; Daali, Youssef

    2016-12-01

    Ticagrelor is the unique reversible oral antiplatelet drug commercialized today. During this study, the intestinal permeability of ticagrelor and its potential P-glycoprotein (P-gp)-mediated active transport were assessed. To this end, bidirectional transport of ticagrelor was performed across Caco-2 (human epithelial colorectal adenocarcinoma) monolayer model in the presence and absence of potent P-gp inhibitor valspodar. Ticagrelor presented an apical-basolateral apparent permeability coefficient (Papp ) of 6.0 × 10(-6) cm/s. On the other hand, mean efflux ratio (ER) of 2.71 was observed for ticagrelor describing a higher efflux permeability compared to the influx component. Valspodar showed a significant inhibitory effect on the efflux of ticagrelor suggesting involvement of P-gp in its oral disposition. Co-incubation of the P-gp inhibitor decreased the efflux Papp of ticagrelor from 1.60 × 10(-5) to 1.13 × 10(-5) cm/s and decreased its ER by 70%. Results suggest a modest active transport of ticagrelor by P-gp across the Caco-2 cell monolayer. The co-administration of ticagrelor with a P-gp inhibitor seems altogether unlikely to have an extended impact on pharmacokinetics of ticagrelor and cause bleeding events in patients. © 2016 Société Française de Pharmacologie et de Thérapeutique.

  8. Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux

    Science.gov (United States)

    A. Christopher Oishi; Sari Palmroth; Kurt H. Johnsen; Heather R. McCarthy; Ram. Oren

    2014-01-01

    Soil CO2 efflux (Fsoil) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity,...

  9. Light-dependent bicarbonate uptake and CO2 efflux in the marine microalga Nannochloropsis gaditana.

    Science.gov (United States)

    Huertas, I E; Espie, G S; Colman, B; Lubian, L M

    2000-06-01

    Inorganic carbon (Ci) uptake and efflux has been investigated in the marine microalga Nannochloropsis gaditana Lubian by monitoring CO2 fluxes in cell suspensions using mass spectrometry. Addition of H13CO3- to cell suspensions in the dark caused a transient increase in the CO2 concentration in the medium far in excess of the equilibrium CO2 concentration. The magnitude of this release was dependent on the length of time the cells had been kept in the dark. Once equilibrium between the Ci species had been achieved, a CO2 efflux was observed after saturating light intensity was applied to the cells. External carbonic anhydrase (CA) was not detected nor does this species demonstrate a capacity to take up CO2 by active transport. Photosynthetic O2 evolution and the release CO2 in the dark depend on HCO3- uptake since both were inhibited by the anion exchange inhibitor, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). The bicarbonate uptake mechanism requires light but can also continue for short periods in the dark. Ethoxyzolamide, a CA inhibitor, markedly inhibited CO2 efflux in the dark, indicating that CO2 efflux was dependent upon the intracellular dehydration of HCO3-. These results indicate that Nannochloropsis possesses a bicarbonate uptake system which causes the accumulation of high intracellular Ci levels and an internal CA which maintains the equilibrium between CO2 and HCO3- and thus causes a subsequent release of CO2 to the external medium.

  10. Can celecoxib affect P-glycoprotein-mediated drug efflux? A microPET study

    NARCIS (Netherlands)

    De Vries, Erik F. J.; Doorduin, Janine; Vellinga, Namkje A. R.; Van Waarde, Aren; Dierckx, Rudi A.; Klein, Hans C.

    Introduction: P-glycoprotein (Pgp) is an efflux pump that protects vital organs like the brain from toxic substances, but which is also associated with therapy resistance. The anti-inflammatory drug celecoxib potentiates the efficacy of several cytostatic and neurotropic drugs that are known Pgp

  11. Adaptive resistance in bacteria requires epigenetic inheritance, genetic noise, and cost of efflux pumps.

    Science.gov (United States)

    Motta, Santiago Sandoval; Cluzel, Philippe; Aldana, Maximino

    2015-01-01

    Adaptive resistance emerges when populations of bacteria are subjected to gradual increases of antibiotics. It is characterized by a rapid emergence of resistance and fast reversibility to the non-resistant phenotype when the antibiotic is removed from the medium. Recent work shows that adaptive resistance requires epigenetic inheritance and heterogeneity of gene expression patterns that are, in particular, associated with the production of porins and efflux pumps. However, the precise mechanisms by which inheritance and variability govern adaptive resistance, and what processes cause its reversibility remain unclear. Here, using an efflux pump regulatory network (EPRN) model, we show that the following three mechanisms are essential to obtain adaptive resistance in a bacterial population: 1) intrinsic variability in the expression of the EPRN transcription factors; 2) epigenetic inheritance of the transcription rate of EPRN associated genes; and 3) energetic cost of the efflux pumps activity that slows down cell growth. While the first two mechanisms acting together are responsible for the emergence and gradual increase of the resistance, the third one accounts for its reversibility. In contrast with the standard assumption, our model predicts that adaptive resistance cannot be explained by increased mutation rates. Our results identify the molecular mechanism of epigenetic inheritance as the main target for therapeutic treatments against the emergence of adaptive resistance. Finally, our theoretical framework unifies known and newly identified determinants such as the burden of efflux pumps that underlie bacterial adaptive resistance to antibiotics.

  12. Adaptive resistance in bacteria requires epigenetic inheritance, genetic noise, and cost of efflux pumps.

    Directory of Open Access Journals (Sweden)

    Santiago Sandoval Motta

    Full Text Available Adaptive resistance emerges when populations of bacteria are subjected to gradual increases of antibiotics. It is characterized by a rapid emergence of resistance and fast reversibility to the non-resistant phenotype when the antibiotic is removed from the medium. Recent work shows that adaptive resistance requires epigenetic inheritance and heterogeneity of gene expression patterns that are, in particular, associated with the production of porins and efflux pumps. However, the precise mechanisms by which inheritance and variability govern adaptive resistance, and what processes cause its reversibility remain unclear. Here, using an efflux pump regulatory network (EPRN model, we show that the following three mechanisms are essential to obtain adaptive resistance in a bacterial population: 1 intrinsic variability in the expression of the EPRN transcription factors; 2 epigenetic inheritance of the transcription rate of EPRN associated genes; and 3 energetic cost of the efflux pumps activity that slows down cell growth. While the first two mechanisms acting together are responsible for the emergence and gradual increase of the resistance, the third one accounts for its reversibility. In contrast with the standard assumption, our model predicts that adaptive resistance cannot be explained by increased mutation rates. Our results identify the molecular mechanism of epigenetic inheritance as the main target for therapeutic treatments against the emergence of adaptive resistance. Finally, our theoretical framework unifies known and newly identified determinants such as the burden of efflux pumps that underlie bacterial adaptive resistance to antibiotics.

  13. Noradrenaline and dopamine efflux in the prefrontal cortex in relation to appetitive classical conditioning

    NARCIS (Netherlands)

    Mingote, Susana; de Bruin, Jan P. C.; Feenstra, Matthijs G. P.

    2004-01-01

    We trained rats to learn that an auditory stimulus predicted delivery of reward pellets in the Skinner box. After 2 d of training, we measured changes in efflux of noradrenaline (NA) and dopamine (DA) in the medial prefrontal cortex using microdialysis on the third day. Animals were subjected to a

  14. Dopamine efflux in nucleus accumbens shell and core in response to appetitive classical conditioning

    NARCIS (Netherlands)

    Cheng, J. J.; de Bruin, J. P. C.; Feenstra, M. G. P.

    2003-01-01

    Dopamine transmission within the nucleus accumbens has been implicated in associative reinforcement learning. We investigated the effect of appetitive classical conditioning on dopamine efflux in the rat nucleus accumbens shell and core, as dopamine may be differentially activated by conditioned and

  15. The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

    Science.gov (United States)

    Plésiat, Patrick

    2015-01-01

    SUMMARY The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps. PMID:25788514

  16. Effect of ABCG2/BCRP Expression on Efflux and Uptake of Gefitinib in NSCLC Cell Lines.

    Directory of Open Access Journals (Sweden)

    Maricla Galetti

    Full Text Available BCRP/ABCG2 emerged as an important multidrug resistance protein, because it confers resistance to several classes of cancer chemotherapeutic agents and to a number of novel molecularly-targeted therapeutics such as tyrosine kinase inhibitors. Gefitinib is an orally active, selective EGFR tyrosine kinase inhibitor used in the treatment of patients with advanced non small cell lung cancer (NSCLC carrying activating EGFR mutations. Membrane transporters may affect the distribution and accumulation of gefitinib in tumour cells; in particular a reduced intracellular level of the drug may result from poor uptake, enhanced efflux or increased metabolism.The present study, performed in a panel of NSCLC cell lines expressing different ABCG2 plasma membrane levels, was designed to investigate the effect of the efflux transporter ABCG2 on intracellular gefitinib accumulation, by dissecting the contribution of uptake and efflux processes.Our findings indicate that gefitinib, in lung cancer cells, inhibits ABCG2 activity, as previously reported. In addition, we suggest that ABCG2 silencing or overexpression affects intracellular gefitinib content by modulating the uptake rather than the efflux. Similarly, overexpression of ABCG2 affected the expression of a number of drug transporters, altering the functional activities of nutrient and drug transport systems, in particular inhibiting MPP, glucose and glutamine uptake.Therefore, we conclude that gefitinib is an inhibitor but not a substrate for ABCG2 and that ABCG2 overexpression may modulate the expression and activity of other transporters involved in the uptake of different substrates into the cells.

  17. Xenon for tunnelling analysis of the efflux pump component OprN.

    Directory of Open Access Journals (Sweden)

    Yvette Véronique Ntsogo Enguéné

    Full Text Available Tripartite efflux pumps are among the main actors responsible for antibiotics resistance in Gram-negative bacteria. In the last two decades, structural studies gave crucial information about the assembly interfaces and the mechanistic motions. Thus rigidifying the assembly seems to be an interesting way to hamper the drug efflux. In this context, xenon is a suitable probe for checking whether small ligands could act as conformational lockers by targeting hydrophobic cavities. Here we focus on OprN, the outer membrane channel of the MexEF efflux pump from Pseudomonas aeruginosa. After exposing OprN crystals to xenon gas pressure, 14 binding sites were observed using X-ray crystallography. These binding sites were unambiguously characterized in hydrophobic cavities of OprN. The major site is observed in the sensitive iris-like region gating the channel at the periplasmic side, built by the three key-residues Leu 405, Asp 109, and Arg 412. This arrangement defines along the tunnel axis a strong hydrophobic/polar gradient able to enhance the passive efflux mechanism of OprN. The other xenon atoms reveal strategic hydrophobic regions of the channel scaffold to target, with the aim to freeze the dynamic movements responsible of the open/close conformational equilibrium in OprN.

  18. Piperine analogs as potent Staphylococcus aureus NorA efflux pump inhibitors

    DEFF Research Database (Denmark)

    Sangwan, Payare L; Koul, Jawahir L; Koul, Surrinder

    2008-01-01

    Based on our recent findings that piperine is a potent Staphylococcus aureus NorA efflux pump inhibitor (EPI), 38 piperine analogs were synthesized and bioevaluated for their EPI activity. Twenty-five of them were found active with potentiating activity equivalent or more than known EPIs like...

  19. Effect of a pharmacological stressor on glutamate efflux in the prefrontal cortex

    NARCIS (Netherlands)

    Karreman, M; Moghaddam, B

    1996-01-01

    The anxiogenic beta-carboline, FG 7142 (20 mg/kg) significantly increased glutamate efflux in the prefrontal cortex of conscious rats as assessed by microdialysis. Pretreatment with the benzodiazepine receptor agonist, diazepam (5 mg/kg), abolished this effect. These findings indicate that

  20. Impact of heme oxygenase-1 on cholesterol synthesis, cholesterol efflux and oxysterol formation in cultured astroglia.

    Science.gov (United States)

    Hascalovici, Jacob R; Song, Wei; Vaya, Jacob; Khatib, Soliman; Fuhrman, Bianca; Aviram, Michael; Schipper, Hyman M

    2009-01-01

    Up-regulation of heme oxygenase-1 (HO-1) and altered cholesterol (CH) metabolism are characteristic of Alzheimer-diseased neural tissues. The liver X receptor (LXR) is a molecular sensor of CH homeostasis. In the current study, we determined the effects of HO-1 over-expression and its byproducts iron (Fe(2+)), carbon monoxide (CO) and bilirubin on CH biosynthesis, CH efflux and oxysterol formation in cultured astroglia. HO-1/LXR interactions were also investigated in the context of CH efflux. hHO-1 over-expression for 3 days ( approximately 2-3-fold increase) resulted in a 30% increase in CH biosynthesis and a two-fold rise in CH efflux. Both effects were abrogated by the competitive HO inhibitor, tin mesoporphyrin. CO, released from administered CORM-3, significantly enhanced CH biosynthesis; a combination of CO and iron stimulated CH efflux. Free iron increased oxysterol formation three-fold. Co-treatment with LXR antagonists implicated LXR activation in the modulation of CH homeostasis by heme degradation products. In Alzheimer's disease and other neuropathological states, glial HO-1 induction may transduce ambient noxious stimuli (e.g. beta-amyloid) into altered patterns of glial CH homeostasis. As the latter may impact synaptic plasticity and neuronal repair, modulation of glial HO-1 expression (by pharmacological or other means) may confer neuroprotection in patients with degenerative brain disorders.

  1. Citral derived amides as potent bacterial NorA efflux pump inhibitors

    DEFF Research Database (Denmark)

    Thota, Niranjan; Koul, Surrinder; Reddy, Mallepally V

    2008-01-01

    Monoterpene citral and citronellal have been used as starting material for the preparation of 5,9-dimethyl-deca-2,4,8-trienoic acid amides and 9-formyl-5-methyl-deca-2,4,8-trienoic acid amides. The amides on bioevaluation as efflux pump inhibitors (EPIs) against Staphylococcus aureus 1199 and Nor...

  2. Improving the accuracy of the gradient method for determining soil carbon dioxide efflux

    Science.gov (United States)

    Continuous soil CO2 efflux (Fsoil) estimates can be obtained by the gradient method (GM), but the utility of the method is hindered by uncertainties in the application of published models for the diffusion coefficient (Ds). We compared two in-situ methods for determining Ds, one based calibrating th...

  3. Involvement of the efflux pumps in chloramphenicol selected strains of Burkholderia thailandensis: proteomic and mechanistic evidence.

    Directory of Open Access Journals (Sweden)

    Fabrice V Biot

    Full Text Available Burkholderia is a bacterial genus comprising several pathogenic species, including two species highly pathogenic for humans, B. pseudomallei and B. mallei. B. thailandensis is a weakly pathogenic species closely related to both B. pseudomallei and B. mallei. It is used as a study model. These bacteria are able to exhibit multiple resistance mechanisms towards various families of antibiotics. By sequentially plating B. thailandensis wild type strains on chloramphenicol we obtained several resistant variants. This chloramphenicol-induced resistance was associated with resistance against structurally unrelated antibiotics including quinolones and tetracyclines. We functionally and proteomically demonstrate that this multidrug resistance phenotype, identified in chloramphenicol-resistant variants, is associated with the overexpression of two different efflux pumps. These efflux pumps are able to expel antibiotics from several families, including chloramphenicol, quinolones, tetracyclines, trimethoprim and some β-lactams, and present a partial susceptibility to efflux pump inhibitors. It is thus possible that Burkholderia species can develop such adaptive resistance mechanisms in response to antibiotic pressure resulting in emergence of multidrug resistant strains. Antibiotics known to easily induce overexpression of these efflux pumps should be used with discernment in the treatment of Burkholderia infections.

  4. Two coregulated efflux transporters modulate intracellular heme and protoporphyrin IX availability in Streptococcus agalactiae.

    Directory of Open Access Journals (Sweden)

    Annabelle Fernandez

    2010-04-01

    Full Text Available Streptococcus agalactiae is a major neonatal pathogen whose infectious route involves septicemia. This pathogen does not synthesize heme, but scavenges it from blood to activate a respiration metabolism, which increases bacterial cell density and is required for full virulence. Factors that regulate heme pools in S. agalactiae are unknown. Here we report that one main strategy of heme and protoporphyrin IX (PPIX homeostasis in S. agalactiae is based on a regulated system of efflux using two newly characterized operons, gbs1753 gbs1752 (called pefA pefB, and gbs1402 gbs1401 gbs1400 (called pefR pefC pefD, where pef stands for 'porphyrin-regulated efflux'. In vitro and in vivo data show that PefR, a MarR-superfamily protein, is a repressor of both operons. Heme or PPIX both alleviate PefR-mediated repression. We show that bacteria inactivated for both Pef efflux systems display accrued sensitivity to these porphyrins, and give evidence that they accumulate intracellularly. The DeltapefR mutant, in which both pef operons are up-regulated, is defective for heme-dependent respiration, and attenuated for virulence. We conclude that this new efflux regulon controls intracellular heme and PPIX availability in S. agalactiae, and is needed for its capacity to undergo respiration metabolism, and to infect the host.

  5. Lack of efflux mediated quinolone resistance in Salmonella enterica serovars Typhi and Paratyphi A

    Directory of Open Access Journals (Sweden)

    Sylvie eBaucheron

    2014-01-01

    Full Text Available Salmonella enterica serovars Typhi and Paratyphi A isolates from human patients in France displaying different levels of resistance to quinolones or fluoroquinolones were studied for resistance mechanisms to these antimicrobial agents. All resistant isolates carried either single or multiple target gene mutations (i.e. in gyrA, gyrB, or parC correlating with the resistance levels observed. Active efflux, through upregulation of multipartite efflux systems, has also been previously reported as contributing mechanism for other serovars. Therefore, we investigated also the occurrence of non-target gene mutations in regulatory regions affecting efflux pump expression. However, no mutation was detected in these regions in both Typhi and Paratyphi isolates of this study. Besides, no overexpression of the major efflux systems was observed for these isolates. Nevertheless, a large deletion of 2334 bp was identified in the acrS-acrE region of all S. Typhi strains but which did not affect the resistance phenotype. As being specific to S. Typhi, this deletion could be used for specific molecular detection purposes. In conclusion, the different levels of quinolone or FQ resistance in both S. Typhi and S. Paratyphi A seem to rely only on target modifications.

  6. Regulated efflux of photoreceptor outer segment-derived cholesterol by human RPE cells.

    Science.gov (United States)

    Storti, Federica; Raphael, Gabriele; Griesser, Vera; Klee, Katrin; Drawnel, Faye; Willburger, Carolin; Scholz, Rebecca; Langmann, Thomas; von Eckardstein, Arnold; Fingerle, Jürgen; Grimm, Christian; Maugeais, Cyrille

    2017-09-21

    Genetic studies have linked age-related macular degeneration (AMD) to genes involved in high-density lipoprotein (HDL) metabolism, including ATP-binding cassette transporter A1 (ABCA1). The retinal pigment epithelium (RPE) handles large amounts of lipids, among others cholesterol, partially derived from internalized photoreceptor outer segments (OS) and lipids physiologically accumulate in the aging eye. To analyze the potential function of ABCA1 in the eye, we measured cholesterol efflux, the first step of HDL generation, in RPE cells. We show the expression of selected genes related to HDL metabolism in mouse and human eyecups as well as in ARPE-19 and human primary RPE cells. Immunofluorescence staining revealed localization of ABCA1 on both sides of polarized RPE cells. This was functionally confirmed by directional efflux to apolipoprotein AI (ApoA-I) of (3)H-labeled cholesterol given to the cells via serum or via OS. ABCA1 expression and activity was modulated using a liver-X-receptor (LXR) agonist and an ABCA1 neutralizing antibody, demonstrating that the efflux was ABCA1-dependent. We concluded that the ABCA1-mediated lipid efflux pathway, and hence HDL biosynthesis, is functional in RPE cells towards both the basal (choroidal) and apical (subretinal) space. Impaired activity of the pathway might cause age-related perturbations of lipid homeostasis in the outer retina and thus may contribute to disease development and/or progression. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Effect of soil compaction and biomass removal on soil CO2 efflux in a Missouri forest

    Science.gov (United States)

    Felix, Jr. Ponder

    2005-01-01

    Forest disturbances associated with harvesting activities can affect soil properties and soil respiration. A soda-lime technique was used to measure soil carbon dioxide (CO2) efflux rates in clearcut plots of a Missouri oak-hickory (Quercus spp. L.-Carya spp. Nutt.) forest 4 years after being treated with two levels of forest...

  8. Comparison of surficial CO2 efflux to other measures of subsurface crude oil degradation

    Science.gov (United States)

    Warren, Ean; Sihota, Natasha J.; Hostettler, Frances D.; Bekins, Barbara A.

    2014-01-01

    At a spill site near Bemidji, Minnesota, crude oil at the water table has been undergoing anaerobic biodegradation for over 30 years. Previous work at this site has shown that methane produced from biodegradation of the oil migrates upward and is oxidized in a methanotrophic zone midway between the water table and the surface. To compare microbial activity measurement methods from multiple locations in the oil body, surficial carbon dioxide efflux, methanogen and methanotroph concentrations, and oil degradation state were collected. Carbon dioxide effluxes over the oil body averaged more than four times those at the background site. Methanotrophic bacteria concentrations measured using pmoA were over 105 times higher above the oil-contaminated sediments compared with the background site. Methanogenic archaea measured using mcrA ranged from 105 to over 107 in the oil and were below detection in the background. Methanogens correlated very well with methanotroph concentrations (r = 0.99), n-alkylcyclohexane losses as a proxy for degradation state (r = − 0.96), and somewhat less well with carbon dioxide efflux (r = 0.92). Carbon dioxide efflux similarly correlated to methanotroph concentrations (r = 0.90) and n-alkylcyclohexane losses (r = − 0.91).

  9. Oral and inhaled corticosteroids: Differences in P-glycoprotein (ABCB1) mediated efflux

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, Andrew, E-mail: a.p.crowe@curtin.edu.au; Tan, Ai May

    2012-05-01

    There is concern that P-glycoprotein mediated efflux contributes to steroid resistance. Therefore, this study examined bidirectional corticosteroid transport and induction capabilities for P-glycoprotein (P-gp) to understand which of the systemic and inhaled corticosteroids interacted with P-gp to the greatest extent. Hydrocortisone, prednisolone, prednisone, methylprednisolone, and dexamethasone represented systemically active drugs, while fluticasone propionate, beclomethasone dipropionate, ciclesonide and budesonide represented inhaled corticosteroids. Aldosterone and fludrocortisone represented mineralocorticoids. All drugs were detected using individually optimised HPLC protocols. Transport studies were conducted through Caco-2 monolayers. Hydrocortisone and aldosterone had efflux ratios below 1.5, while prednisone showed a P-gp mediated efflux ratio of only 1.8 compared to its active drug, prednisolone, with an efflux ratio of 4.5. Dexamethasone and beclomethasone had efflux ratios of 2.1 and 3.3 respectively, while this increased to 5.1 for methylprednisolone. Fluticasone showed an efflux ratio of 2.3. Protein expression studies suggested that all of the inhaled corticosteroids were able to induce P-gp expression, from 1.6 to 2 times control levels. Most of the systemic corticosteroids had higher passive permeability (> 20 × 10{sup −6} cm/s) compared to the inhaled corticosteroids (> 5 × 10{sup −6} cm/s), except for budesonide, with permeability similar to the systemic corticosteroids. Inhaled corticosteroids are not transported by P-gp to the same extent as systemic corticosteroids. However, they are able to induce P-gp production. Thus, inhaled corticosteroids may have greater interactions with other P-gp substrates, but P-gp itself is less likely to influence resistance to the drugs. -- Highlights: ► Inhaled corticosteroids are only weak substrates for P-gp, including budesonide. ► Inhaled corticosteroid potent P-gp inducers especially

  10. High-density lipoprotein cholesterol efflux capacity as a relevant predictor of atherosclerotic coronary disease.

    Science.gov (United States)

    Ishikawa, Tetsuya; Ayaori, Makoto; Uto-Kondo, Harumi; Nakajima, Takatomo; Mutoh, Makoto; Ikewaki, Katsunori

    2015-09-01

    We examined the clinical relevance of high-density lipoprotein cholesterol (HDL-C) efflux capacity from macrophage (cholesterol efflux capacity) as a predictor of atherosclerotic coronary artery disease (CAD) in comparison with that of conventional coronary and lipid risk variables in Japanese daily practice. Fasting blood sampling, including 6 routinely measured dyslipidemia-related variables, was performed at the time of coronary angiography (CAG) or multi-slice coronary computed tomography (MSCT) between January 2011 and January 2013. CAD, defined as native coronary atherosclerosis stenosis >50% by CAG or MSCT, was identified in 182 patients (CAD group), but not in 72 patients (non-CAD group). Cholesterol efflux capacity, measured using a cell-based efflux system in (3)[H]-cholesterol-labeled J774 macrophages in apolipoprotein B-depleted plasma, was significantly impaired in the CAD group compared with the non-CAD group (0.86 ± 0.26 vs. 1.02 ± 0.38; p = 0.001). After adjusting 15 patient and dyslipidemia-related variables using a propensity score matching analysis produced 55 patients in each arm, cholesterol efflux capacity in the CAD group remained to be significant compared with the non-CAD group (0.83 ± 0.24 vs. 0.97 ± 0.36; p = 0.019). Stepwise logistic regression analysis using a backward method after the baseline adjustment showed that cholesterol efflux capacity (odds ratio [OR]: 0.23; 95% confidence interval [CI]: 0.056-0.91; p = 0.037) was the single predictor of CAD, while other variables including HDL-C (p = 0.088) and apolipoprotein (apo) A-I (p = 0.681) were removed owing to those insignificance. The area under the receiver operating characteristic curve after the baseline adjustment was 0.67 (95% CI: 0.51-0.73, p = 0.048 by Hosmer-Lemeshow goodness-of-fit statistics). The present observational study conducted under daily clinical practice confirmed that cholesterol efflux capacity is a clinically relevant predictor of CAD among the

  11. The contributions of nitrate uptake and efflux to isotope fractionation during algal nitrate assimilation

    Science.gov (United States)

    Karsh, K. L.; Trull, T. W.; Sigman, D. M.; Thompson, P. A.; Granger, J.

    2014-05-01

    In order to strengthen environmental application of nitrate N and O isotopes, we measured the N and O isotopic fractionation associated with cellular nitrate uptake and efflux in the nitrate-assimilating marine diatom Thalassiosira weissflogii. We isolated nitrate uptake and efflux from nitrate reduction by growing the cells in the presence of tungsten, which substitutes for molybdenum in assimilatory nitrate reductase, yielding an inactive enzyme. After growth on ammonium and then N starvation, cells were exposed to nitrate. Numerical models fit to the evolution of intracellular nitrate concentration and N and O isotopic composition yielded distinct N isotope effects (15ɛ) for nitrate uptake and nitrate efflux (2.0 ± 0.3‰ and 1.2 ± 0.4‰, respectively). The O isotope effects (18ɛ) for nitrate uptake and nitrate efflux were indistinguishable (2.8 ± 0.6‰), yielding a ratio of O to N isotopic fractionation for uptake of 1.4 ± 0.4 and for efflux of 2.3 ± 0.9. The 15ɛ for nitrate uptake can account for at most 40% of the organism-level N isotope effect (15ɛorg) measured in laboratory studies of T. weissflogii and in the open ocean (typically 5‰ or greater). This observation supports previous evidence that most isotope fractionation during nitrate assimilation is due to intracellular nitrate reduction, with nitrate efflux allowing the signal to be communicated to the environment. An O to N fractionation ratio (18ɛorg:15ɛorg) of ˜1 has been measured for nitrate assimilation in algal cultures and linked to the N and O isotope effects of nitrate reductase. Our results suggest that the ratios of O to N fractionation for both nitrate uptake and efflux may be distinct from a ratio of 1, to a degree that could cause the net 18ɛorg:15ɛorg to rise appreciably above 1 when 15ɛorg is low (e.g., yielding a ratio of 1.1 when 15ɛorg is 5‰). However, field and culture studies have consistently measured nearly equivalent fractionation of N and O isotopes in

  12. Role of Efflux Pumps and Intracellular Thiols in Natural Antimony Resistant Isolates of Leishmania donovani

    Science.gov (United States)

    Rai, Smita; Bhaskar; Goel, Sudhir K.; Nath Dwivedi, Upendra; Sundar, Shyam; Goyal, Neena

    2013-01-01

    Background In view of the recent upsurge in the phenomenon of therapeutic failure, drug resistance in Leishmania, developed under natural field conditions, has become a great concern yet little understood. Accordingly, the study of determinants of antimony resistance is urgently warranted. Efflux transporters have been reported in Leishmania but their role in clinical resistance is still unknown. The present study was designed to elucidate the mechanism of natural antimony resistance in L. donovani field isolates by analyzing the functionality of efflux pump(s) and expression profiles of known genes involved in transport and thiol based redox metabolism Methodology/Principal Findings We selected 7 clinical isolates (2 sensitive and 5 resistant) in addition to laboratory sensitive reference and SbIII resistant mutant strains for the present study. Functional characterization using flow cytometry identified efflux pumps that transported substrates of both P-gp and MRPA and were inhibited by the calmodulin antagonist trifluoperazine. For the first time, verapamil sensitive efflux pumps for rhodamine 123 were observed in L. donovani that were differentially active in resistant isolates. RT-PCR confirmed the over-expression of MRPA in isolates with high resistance index only. Resistant isolates also exhibited consistent down regulation of AQP1 and elevated intracellular thiol levels which were accompanied with increased expression of ODC and TR genes. Interestingly, γ-GCS is not implicated in clinical resistance in L. donovani isolates. Conclusions/Significance Here we demonstrate for the first time, the role of P-gp type plasma membrane efflux transporter(s) in antimony resistance in L. donovani field isolates. Further, decreased levels of AQP1 and elevated thiols levels have emerged as biomarkers for clinical resistance. PMID:24069359

  13. MAPK1 of Leishmania donovani modulates antimony susceptibility by downregulating P-glycoprotein efflux pumps.

    Science.gov (United States)

    Garg, Mansi; Goyal, Neena

    2015-07-01

    Emergence of resistance to pentavalent antimonials has become a severe obstacle in the treatment of visceral leishmaniasis (VL) in the Indian subcontinent. Mitogen-activated protein kinases (MAPKs) are well-known mediators of signal transduction of eukaryotes, regulating important processes, like proliferation, differentiation, stress response, and apoptosis. In Leishmania, MAPK1 has been shown to be consistently downregulated in antimony-resistant field isolates, suggesting that it has a role in antimony resistance. The present work investigates the molecular mechanism of MAPK1 in antimony resistance in Leishmania donovani. The L. donovani MAPK1 (LdMAPK1) single-allele replacement mutants exhibited increased resistance to Sb(III) (5.57-fold) compared to wild-type promastigotes, while overexpressing parasites became much more susceptible to antimony. The LdMAPK1-mediated drug sensitivity was directly related to antimony-induced apoptotic death of the parasite, as was evidenced by a 4- to 5-fold decrease in cell death parameters in deletion mutants and a 2- to 3-fold increase in MAPK1-overexpressing cells. LdMAPK1-underexpressing parasites also exhibited increased P-glycoprotein (P-gp)-mediated efflux pump activity, while a significant decrease in pump activity was observed in overexpressing cells. This change in efflux pump activity was directly related to expression levels of P-gp in all cell lines. However, episomal complementation of the gene restored normal growth, drug sensitivity, P-gp expression, and efflux pump activity. The data indicate that LdMAPK1 negatively regulates the expression of P-glycoprotein-type efflux pumps in the parasite. The decrease in efflux pump activity with an increase in LdMAPK1 expression may result in increased antimony accumulation in the parasite, making it more vulnerable to the drug. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  14. Effect of vildagliptin and pravastatin combination on cholesterol efflux in adipocytes.

    Science.gov (United States)

    Mostafa, Ahmed M; Hamdy, Nadia M; Abdel-Rahman, Sherif Z; El-Mesallamy, Hala O

    2016-07-01

    Many reports suggested that some statins are almost ineffective in reducing triglycerides or enhancing HDL-C plasma levels, although statin treatment was still efficacious in reducing LDL-C. In diabetic dyslipidemic patients, it may therefore be necessary to use a combination therapy with other drugs to achieve either LDL-C- and triglyceride-lowering or HDL-C-enhancing goals. Such ineffectiveness of statins can be attributed to their effect on the liver X receptor (LXR) which regulates the expression of the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. A decrease in the expression of these transporters eventually leads to decreased cholesterol efflux from peripheral tissues leading to low levels of HDL-C. Although manipulating the LXR pathway may complement the effects of statins, LXR synthetic ligands as T091317 have shown significant hypertriglyceridemic action which limits their use. We recently found that the antidiabetic drug vildagliptin stimulates LXR expression leading to increased ABCB1/ABCG1 expression which improves cholesterol efflux from adipocytes. Therefore, a combination of vildagliptin and statin may provide a solution without the hypertriglyceridemic action observed with LXR agonist. We hypothesize that a combination of vildagliptin and pravastatin will improve cholesterol efflux in adipocytes. Statin-treated 3T3-L1 adipocytes were treated with vildagliptin, and the expression of LXR-ABCA1/ABCG1 cascade and the cholesterol efflux were then determined. Our data indicate that a combination of vildagliptin and pravastatin significantly induces the expression of LXR-ABCA1/ABCG1 cascade and improves cholesterol efflux (P > 0.05) in adipocytes. Our data may explain, at least in part, the improvement in HDL-C levels observed in patients receiving both medications. © 2016 IUBMB Life, 68(7):535-543, 2016. © 2016 International Union of Biochemistry and Molecular Biology.

  15. Importance of Non-Diffusive Transport for Soil CO2 Efflux in a Temperate Mountain Grassland

    Science.gov (United States)

    Roland, Marilyn; Vicca, Sara; Bahn, Michael; Ladreiter-Knauss, Thomas; Schmitt, Michael; Janssens, Ivan A.

    2015-04-01

    A key focus in climate change is on the dynamics and predictions of the soil CO2 efflux (SCE) from terrestrial ecosystems. Limited knowledge of CO2 transport through the soil restricts our understanding of the various biotic and abiotic processes underlying these emissions. Diffusion is often thought to be the main transport mechanism for trace gases in soils, an assumption that is reflected in the increasing popularity of the flux-gradient approach (FGA). Based on Fick's law, the FGA calculates soil CO2 efflux from CO2 concentration profiles, given good estimates of the diffusion coefficient. The latter can be calculated via different commonly used models, and solid-state sensors allow continuous high-frequency measurements of soil CO2 concentrations with minimal disturbance to the soil conditions in a cost-effective way. Fast growing evidence of pressure pumping and advection, makes it impossible to disregard non-diffusive gas transport when evaluating diel and day-to-day dynamics of soil CO2 emissions. We have analyzed combined measurements from solid-state sensors and soil chambers to gain insight in the CO2 transport mechanisms in a grassland site in the Austrian Alps. The FGA-derived efflux underestimated the chamber efflux by 10 to 87% at our site, depending on which model was used for calculation of the diffusion coefficient. We found that the actual transport rates correlated well with irradiation and wind speed, even more when the soil moisture content was below 33%. These findings suggest that bulk soil air transport was enhanced by pressure changes induced by wind shear at the surface and by local heating of the soil surface. Considering the importance of non-diffusive transport processes is a prerequisite when using solid-state CO2 concentration measurements to estimate soil CO2 efflux at any given site.

  16. Proof of concept for a novel functional screening system for plant sucrose effluxers

    Directory of Open Access Journals (Sweden)

    Yuchan Zhou

    2014-07-01

    Full Text Available Membrane transporters play pivotal roles in facilitating sucrose transport in plants and their activities have been shown to impact plant growth rates and crop yield.  In contrast to the well-defined mechanism of sucrose influx across plasma membranes, less is known about sucrose efflux mechanisms and the membrane proteins supporting this function.  A major impediment blocking progress in this key area of plant science is the absence of a functional screening system for genes encoding sucrose effluxers.  Here we report a novel yeast system for screening sucrose effluxers based on sucrose release from yeast cells genetically modified to synthesize, but not to metabolize, sucrose.  Inhibiting sucrose metabolism was achieved using yeast strains, SEY 6210 and YSL4-6, carrying mutations in genes encoding invertase and maltase, respectively.  Genes encoding essential components of sucrose biosynthesis, sucrose phosphate synthase (SPS and sucrose phosphate phosphatase (SPP, were used to transform the two yeast hosts to make strains SuPy (from SEY6210 and Ysu (from YSL4-6.  Cultures of SuPy15 cells were found to be capable of synthesizing sucrose when supplied with various compounds as the sole carbon source, including non-fermentable sugars and non-sugar substrates.  A proof of concept of the screening system was demonstrated by transforming SuPy15 with sucrose transporter genes known to encode plasma membrane proteins that mediate sucrose efflux.  The robustness of the yeast SuPy15 system as a novel platform to screen putative plant sucrose effluxers is discussed.

  17. Hyposmolarity evokes norepinephrine efflux from synaptosomes by a depolarization- and Ca2+ -dependent exocytotic mechanism.

    Science.gov (United States)

    Tuz, K; Pasantes-Morales, H

    2005-10-01

    Osmolarity reduction (20%) elicited 3H-norepinephrine (NE) efflux from rat cortical synaptosomes. The hyposmotic NE release resulted from the following events: (i) a Na+-dependent and La3+-, Gd3+- and ruthenium red-sensitive depolarization; (ii) a cytosolic Ca2+ ([Ca2+]i) rise with contributions from external Ca2+ influx and internal Ca2+ release, probably through the mitochondrial Na+-Ca2+ exchanger; and (iii) activation of a [Ca2+]i-evoked, tetanus toxin (TeTX)-sensitive, PKC-modulated NE efflux mechanism. This sequence was established from results showing a drop in the hyposmotic [Ca2+]i rise by preventing depolarization with La3+, and by the inhibitory effects of Ca2+-free medium (EGTA; 50%), CGP37157 (the mitochondrial Na+-Ca2+ exchanger blocker; 48%), EGTA + CGP37157 or by EGTA-AM (> 95% in both cases). In close correspondence with these effects, NE efflux was 92% decreased by Na+ omission, 75% by La3+, 47% by EGTA, 50% by CGP37157, 90% by EGTA + CGP37157 and 88% by EGTA-AM. PKC influenced the intracellular Ca2+ release and, mainly through this action, modulated NE efflux. TeTX suppressed NE efflux. The K+-stimulated NE release, studied in parallel, was unaffected by Na+ omission, or by La3+, Gd3+ or ruthenium red. It was fully dependent on external Ca2+, insensitive to CGP37157 and abolished by TeTX. These results suggest that the hyposmotic events, although different from the K+-evoked depolarization and [Ca2+]i rise mechanisms, are able to trigger a depolarization-dependent, Ca2+-dependent and TeTX-sensitive mechanism for neurotransmitter release.

  18. Overestimation of closed-chamber soil CO2 effluxes at low atmospheric turbulence

    Science.gov (United States)

    Brændholt, Andreas; Steenberg Larsen, Klaus; Ibrom, Andreas; Pilegaard, Kim

    2017-03-01

    Soil respiration (Rs) is an important component of ecosystem carbon balance, and accurate quantification of the diurnal and seasonal variation of Rs is crucial for a correct interpretation of the response of Rs to biotic and abiotic factors, as well as for estimating annual soil CO2 efflux rates. In this study, we measured Rs hourly for 1 year by automated closed chambers in a temperate Danish beech forest. The data showed a clear diurnal pattern of Rs across all seasons with higher rates during night-time than during daytime. However, further analysis showed a clear negative relationship between flux rates and friction velocity (u∗) above the canopy, suggesting that Rs was overestimated at low atmospheric turbulence throughout the year due to non-steady-state conditions during measurements. Filtering out data at low u∗ values removed or even inverted the observed diurnal pattern, such that the highest effluxes were now observed during daytime, and also led to a substantial decrease in the estimated annual soil CO2 efflux. By installing fans to produce continuous turbulent mixing of air around the soil chambers, we tested the hypothesis that overestimation of soil CO2 effluxes during low u∗ can be eliminated if proper mixing of air is ensured, and indeed the use of fans removed the overestimation of Rs rates during low u∗. Artificial turbulent air mixing may thus provide a method to overcome the problems of using closed-chamber gas-exchange measurement techniques during naturally occurring low atmospheric turbulence conditions. Other possible effects from using fans during soil CO2 efflux measurements are discussed. In conclusion, periods with low atmospheric turbulence may provide a significant source of error in Rs rates estimated by the use of closed-chamber techniques and erroneous data must be filtered out to obtain unbiased diurnal patterns, accurate relationships to biotic and abiotic factors, and before estimating Rs fluxes over longer timescales.

  19. Efflux protein expression in human stem cell-derived retinal pigment epithelial cells.

    Directory of Open Access Journals (Sweden)

    Kati Juuti-Uusitalo

    Full Text Available Retinal pigment epithelial (RPE cells in the back of the eye nourish photoreceptor cells and form a selective barrier that influences drug transport from the blood to the photoreceptor cells. At the molecular level, ATP-dependent efflux transporters have a major role in drug delivery in human RPE. In this study, we assessed the relative expression of several ATP-dependent efflux transporter genes (MRP1, -2, -3, -4, -5, -6, p-gp, and BCRP, the protein expression and localization of MRP1, MRP4, and MRP5, and the functionality of MRP1 efflux pumps at different maturation stages of undifferentiated human embryonic stem cells (hESC and RPE derived from the hESC (hESC-RPE. Our findings revealed that the gene expression of ATP-dependent efflux transporters MRP1, -3, -4, -5, and p-gp fluctuated during hESC-RPE maturation from undifferentiated hESC to fusiform, epithelioid, and finally to cobblestone hESC-RPE. Epithelioid hESC-RPE had the highest expression of MRP1, -3, -4, and P-gp, whereas the most mature cobblestone hESC-RPE had the highest expression of MRP5 and MRP6. These findings indicate that a similar efflux protein profile is shared between hESC-RPE and the human RPE cell line, ARPE-19, and suggest that hESC-RPE cells are suitable in vitro RPE models for drug transport studies. Embryonic stem cell model might provide a novel tool to study retinal cell differentiation, mechanisms of RPE-derived diseases, drug testing and targeted drug therapy.

  20. Efflux and hydrolysis of phosphorylethanolamine and phosphorylcholine in stressed cultured rat lenses.

    Science.gov (United States)

    Jernigan, H M; Desouky, M A; Geller, A M; Blum, P S; Ekambaram, M C

    1993-01-01

    Phosphorylcholine (P-choline), and phosphorylethanolamine (P-ethanolamine) are among the organic phosphate compounds that decrease in concentration in some cataracts and in lenses that have been subjected to cataractogenic osmotic or oxidative stresses. Decreases in the lenticular concentrations of these compounds could be caused by decreased synthesis, increased utilization or hydrolysis, or increased efflux, or by a combination of these mechanisms. To distinguish between these possibilities, the P-choline and P-ethanolamine pools of intact cultured rat lenses were radiolabeled with [3H]choline or [3H]ethanolamine, and the lenses were then subjected to oxidative or osmotic stress. The efflux and hydrolysis of P-[3H]choline and P-[3H]ethanolamine were then followed for up to 48 hr. Osmotic stress induced by incubation with 30 mM xylose caused increased P-choline and P-ethanolamine efflux from the lenses, but had little effect on the rate of hydrolysis of these compounds. For example, xylose-treated lenses lost 26% of their initial P-[3H]ethanolamine content into the medium during a 24 hr incubation, compared with only 6% for control lenses. Oxidative stress from singlet oxygen (generated by rose bengal and light) also increased lenticular P-choline efflux three to four-fold, with minimal effects on hydrolysis, and the increased efflux was accompanied by a decrease in the P-choline concentration. Permeability increases also were observed in lenses oxidatively stressed by H2O2 or by riboflavin and light. These results show that a variety of cataractogenic stresses, both oxidative and osmotic, cause increased permeability of rat lenses to organic phosphate compounds, including P-choline and P-ethanolamine.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Kinetics of MDR transport in tumor-initiating cells.

    Science.gov (United States)

    Koshkin, Vasilij; Yang, Burton B; Krylov, Sergey N

    2013-01-01

    Multidrug resistance (MDR) driven by ABC (ATP binding cassette) membrane transporters is one of the major causes of treatment failure in human malignancy. MDR capacity is thought to be unevenly distributed among tumor cells, with higher capacity residing in tumor-initiating cells (TIC) (though opposite finding are occasionally reported). Functional evidence for enhanced MDR of TICs was previously provided using a "side population" assay. This assay estimates MDR capacity by a single parameter - cell's ability to retain fluorescent MDR substrate, so that cells with high MDR capacity ("side population") demonstrate low substrate retention. In the present work MDR in TICs was investigated in greater detail using a kinetic approach, which monitors MDR efflux from single cells. Analysis of kinetic traces obtained allowed for the estimation of both the velocity (V max) and affinity (K M) of MDR transport in single cells. In this way it was shown that activation of MDR in TICs occurs in two ways: through the increase of V max in one fraction of cells, and through decrease of K M in another fraction. In addition, kinetic data showed that heterogeneity of MDR parameters in TICs significantly exceeds that of bulk cells. Potential consequences of these findings for chemotherapy are discussed.

  2. ApoE promotes hepatic selective uptake but not RCT due to increased ABCA1-mediated cholesterol efflux to plasma[S

    Science.gov (United States)

    Annema, Wijtske; Dikkers, Arne; Freark de Boer, Jan; Gautier, Thomas; Rensen, Patrick C. N.; Rader, Daniel J.; Tietge, Uwe J. F.

    2012-01-01

    ApoE plays an important role in lipoprotein metabolism. This study investigated the effects of adenovirus-mediated human apoE overexpression (AdhApoE3) on sterol metabolism and in vivo reverse cholesterol transport (RCT). In wild-type mice, AdhApoE3 resulted in decreased HDL cholesterol levels and a shift toward larger HDL in plasma, whereas hepatic cholesterol content increased (P < 0.05). These effects were dependent on scavenger receptor class B type I (SR-BI) as confirmed using SR-BI-deficient mice. Kinetic studies demonstrated increased plasma HDL cholesteryl ester catabolic rates (P < 0.05) and higher hepatic selective uptake of HDL cholesteryl esters in AdhApoE3-injected wild-type mice (P < 0.01). However, biliary and fecal sterol output as well as in vivo macrophage-to-feces RCT studied with 3H-cholesterol-loaded mouse macrophage foam cells remained unchanged upon human apoE overexpression. Similar results were obtained using hApoE3 overexpression in human CETP transgenic mice. However, blocking ABCA1-mediated cholesterol efflux from hepatocytes in AdhApoE3-injected mice using probucol increased biliary cholesterol secretion (P < 0.05), fecal neutral sterol excretion (P < 0.05), and in vivo RCT (P < 0.01), specifically within neutral sterols. These combined data demonstrate that systemic apoE overexpression increases i) SR-BI-mediated selective uptake into the liver and ii) ABCA1-mediated efflux of RCT-relevant cholesterol from hepatocytes back to the plasma compartment, thereby resulting in unchanged fecal mass sterol excretion and overall in vivo RCT. PMID:22383685

  3. Removal of bromide from aqueous solutions using the UV/ZnO process based on the multivariate analysis model

    Directory of Open Access Journals (Sweden)

    Kolsoom Mohammad Moradi

    2017-02-01

    Full Text Available Background: Bromide is found naturally in groundwater and surface water. The rapid growth of industrial activities, drainage of surface runoff, and use of methyl bromide in pesticides has increased bromide discharge to the environment. Disinfection of water-containing bromide causes the creation of additional products of organo-halogenated that are considered cancer-causing agents. In this study, the effect and optimization of factors in removal of this ion was evaluated by using the nano-photocatalytic UV/ZnO process. Methods: This analytical study was conducted in a batch system by the phenol-red method. The test design was performed through the analysis model of multi-factor variance with 99 subjects, while the main, interactive, and reciprocal effects of variables, such as reaction time, catalyst concentration, bromide concentration, and pH at different levels of each factor, were analysed by using SPSS version 16. Results: The main, interactive, and reciprocal effects of factors were significant in three different levels with P < 0.001, and the optimal level of the factors reaction time, catalyst concentration, bromide concentration, and pH were 120 minutes, 0.5, 0.1, and 7 mg/L, respectively, by using the Schaffer test. The highest removal efficiency of 95% was obtained at least 91.56 and a maximum of 94.76% was obtained under optimal conditions of all factors. Conclusion: The results show that by optimization of factors, this process can be effectively used to remove bromide from aquatic environments.

  4. The effects of pyridostigmine bromide and permethrin, alone or in combination, on response acquisition in male and female rats.

    Science.gov (United States)

    Van Haaren, F; Cody, B; Hoy, J B; Karlix, J L; Schmidt, C J; Tebbett, I R; Wielbo, D

    2000-08-01

    It has been hypothesized that concurrent exposure to pyridostigmine bromide and permethrin may have contributed to the development of neurocognitive symptoms in Gulf War veterans. The present experiment was designed to investigate the effects of pyridostigmine bromide and permethrin alone, or in combination, on the acquisition of a novel response, one measure of normal cognitive functioning. Male and female Sprague-Dawley rats were treated with pyridostigmine bromide (1.5 mg/kg/day, by gavage in a volume of 5 ml/kg) or its vehicle for 7 consecutive days. They then also received an intraperitoneal injection of permethrin (0, 15, or 60 mg/kg) before they were exposed to an experimental session during which they could earn food by pressing a lever in an operant chamber. Serum permethrin levels increased as a function of its dose, and were higher in rats treated with pyridostigmine bromide. Sex differences were observed as permethrin levels were higher in female rats than in male rats following the highest dose. Pyridostigmine bromide delayed response acquisition in male and female rats, and resulted in higher response rates on the inactive lever in female rats than in male rats. Although permethrin levels were higher in subjects treated with pyridostigmine bromide than in those treated with vehicle, there were no differences in the behavioral effects of permethrin. Whether or not these behavioral effects of pyridostigmine bromide are of central or peripheral origin will need to be determined in future studies, as its effects on motor activity and/or gastro-intestinal motility may have affected response acquisition.

  5. Effect of chronic administration of phenobarbital, or bromide, on pharmacokinetics of levetiracetam in dogs with epilepsy.

    Science.gov (United States)

    Muñana, K R; Nettifee-Osborne, J A; Papich, M G

    2015-01-01

    Levetiracetam (LEV) is a common add-on antiepileptic drug (AED) in dogs with refractory seizures. Concurrent phenobarbital administration alters the disposition of LEV in healthy dogs. To evaluate the pharmacokinetics of LEV in dogs with epilepsy when administered concurrently with conventional AEDs. Eighteen client-owned dogs on maintenance treatment with LEV and phenobarbital (PB group, n = 6), LEV and bromide (BR group, n = 6) or LEV, phenobarbital and bromide (PB-BR group, n = 6). Prospective pharmacokinetic study. Blood samples were collected at 0, 1, 2, 4, and 6 hours after LEV administration. Plasma LEV concentrations were determined by high-pressure liquid chromatography. To account for dose differences among dogs, LEV concentrations were normalized to the mean study dose (26.4 mg/kg). Pharmacokinetic analysis was performed on adjusted concentrations, using a noncompartmental method, and area-under-the-curve (AUC) calculated to the last measured time point. Compared to the PB and PB-BR groups, the BR group had significantly higher peak concentration (Cmax ) (73.4 ± 24.0 versus 37.5 ± 13.7 and 26.5 ± 8.96 μg/mL, respectively, P dogs compared to concurrent administration of bromide alone. Dosage increases might be indicated when utilizing LEV as add-on treatment with phenobarbital in dogs. Copyright © 2015 by the American College of Veterinary Internal Medicine.

  6. Ethidium bromide-induced demyelination of the sciatic nerve of adult Wistar rats

    Directory of Open Access Journals (Sweden)

    Riet-Correa G.

    2002-01-01

    Full Text Available Peripheral nerve ultrastructure was assessed after single or multiple local injections of the intercalating dye ethidium bromide. Thirty-four adult Wistar rats of both sexes were divided into five groups and maintained in a controlled environment with rat chow and water ad libitum throughout the experiment. The experimental animals were injected with 1 µl of 0.1% ethidium bromide in 0.9% saline into the central third of the left sciatic nerve 1 (group 1, 2 (group 2, 4 (group 3, 6 (group 4 or 8 (group 5 times. In groups 2 to 5 the injections were made at 28-day intervals. Control animals received the same amount of 0.9% saline. The animals were killed at different times after injection: group 1 at 7 days (2 rats and 15 days (2 rats; for groups 2, 3, 4 and 5, all rats were killed 10 days after the last injection and the lesions were investigated by light and transmission electron microscopy. In the acute lesions, intoxicated Schwann cells showed a vacuolated cytoplasm and separation of the sheaths from the axon. Myelin sheaths underwent progressive vesiculation and subsequent segmental demyelination. Myelin debris were withdrawn by macrophages and remyelination by Schwann cells was prominent. With the increase in the number of injections collagen fibers also increased in number and progressively enveloped smaller numbers of remyelinated axons composing new fascicles. Wallerian degeneration of fibers apparently not affected by ethidium bromide was more intense in the nerves from groups 4 and 5. The peripheral nerve repairs itself after demyelinating challenges with a profusion of collagen fibers and new fasciculations. This experimental model is valid to mimic recurrent demyelinating neuropathies.

  7. Bromide oxidation by ferrate(VI): The formation of active bromine and bromate.

    Science.gov (United States)

    Jiang, Yanjun; Goodwill, Joseph E; Tobiason, John E; Reckhow, David A

    2016-06-01

    Ferrate (VI) (abbreviated as Fe(VI)) has long been considered as a green oxidant that does not produce any known hazardous byproducts. However, this work shows that Fe(VI) can slowly oxidize bromide forming active bromine (HOBr/OBr(-)) and bromate, and in natural waters total organic bromine (TOBr) can also be detected. Results showed that the highest levels of active bromine and bromate were formed at lower pHs and in the absence of phosphate. Hydrogen peroxide, which forms from the reaction of Fe(VI) and water, plays an essential role in suppressing bromate formation by reducing active bromine back to bromide. Fe(VI) decomposition products (assumed to be particulate phase Fe(III)) can catalyze the decomposition of hydrogen peroxide by Fe(VI). Phosphate had a substantial inhibiting effect on the formation of active bromine, but less so on bromate formation. The presence of the raw water matrix in natural water suppressed bromate formation. For a natural water spiked with 0.1 mg/L of bromide, the bromate and TOBr concentrations after Fe(VI) oxidation were below 3.0 and 15 μg/L, respectively. No consistent trend regarding the effect of pH or buffer ions on TOBr formation was observed due to the competition between Fe(VI), hydrogen peroxide, and natural organic matter (NOM) for reaction with active bromine. Under environmentally relevant conditions, the formation of bromate and TOBr would not be a problem for Fe(VI) application as their concentration levels are quite low. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Irreversible processes kinetic theory

    CERN Document Server

    Brush, Stephen G

    2013-01-01

    Kinetic Theory, Volume 2: Irreversible Processes deals with the kinetic theory of gases and the irreversible processes they undergo. It includes the two papers by James Clerk Maxwell and Ludwig Boltzmann in which the basic equations for transport processes in gases are formulated, together with the first derivation of Boltzmann's ""H-theorem"" and a discussion of this theorem, along with the problem of irreversibility.Comprised of 10 chapters, this volume begins with an introduction to the fundamental nature of heat and of gases, along with Boltzmann's work on the kinetic theory of gases and s

  9. Efficient SN2 fluorination of primary and secondary alkyl bromides by copper(I) fluoride complexes

    KAUST Repository

    Liu, Yanpin

    2013-11-11

    Copper(I) fluoride complexes ligated by phenanthroline derivatives have been synthesized and structurally characterized by X-ray crystallography. These complexes adopt as either ionic or neutral forms in the solid state, depending on the steric bulkiness of the substituent groups on the phenanthroline ligands. These complexes react with primary and secondary alkyl bromides to produce the corresponding alkyl fluorides in modest to good yields. This new method is compatible with a variety of important functional groups such as ether, thioether, amide, nitrile, methoxyl, hydroxyl, ketone, ester, and heterocycle moieties. © 2013 American Chemical Society.

  10. Research on Wheat Straw Pulping with Ionic Liquid 1-Ethyl-3-Methylimidazole Bromide

    OpenAIRE

    Wei Song; Yu Deng; Hong Zhu

    2016-01-01

    In this paper, the pulping process of wheat straw using ionic liquid 1-ethyl-3-methylimidazolium bromide ([Emim]Br) as the digestion liquor is presented. The influence of pulping conditions on the pulp yield are analysed by single-factor and orthogonal experiments, and optimum pulping conditions are obtained. The average pulp yield reaches 44 %, and the average recovery rate of ionic liquid is 93.5 %. The XRD pattern shows no obvious change in the crystal structure of the wheat straw cellulos...

  11. Aclidinium bromid forbedrer lungefunktionen og reducerer dyspnø hos patienter med KOL

    DEFF Research Database (Denmark)

    Ulrik, Charlotte Suppli

    2014-01-01

    Long-acting bronchodilators are central for treatment of COPD. This short review provides an overview of studies evaluating the efficacy of aclidinium bromide, a long-acting anticholinergic bronchodilator, for the treatment of COPD. Twice-daily dosing of aclidinium leads to clinically important...... improvements in forced expiratory volume in 1 second, health status, use of rescue medication, day-time dyspnoea and exercise tolerance. The available studies also suggest an effect on night-time dyspnoea and exacerbation rate in patients with COPD. Aclidinium seems to have potential for a significant role...... in the future management of COPD....

  12. 1-Cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide dihydrate

    Directory of Open Access Journals (Sweden)

    Ying Cai

    2010-07-01

    Full Text Available In the crystal structure of the title compound, C8H14N3+·Br−·2H2O, intermolecular O—H...O and O—H...Br hydrogen bonding occurs. The water molecules are connected into chains extending in the a-axis direction. The bromide anions are connected to the water molecules, forming 10-membered rings. The cations are connected to the anions via weak C—H...Br interactions. Two carbon atoms of the cation are disordered and were refined using a split model (occupancy ratio 0.70:0.3.

  13. Environmental and health risks of sulfuryl fluoride, a fumigant replacement for methyl bromide.

    Science.gov (United States)

    Tsai, Wen-Tien

    2010-04-01

    Sulfuryl fluoride (SO(2)F(2)) is used primarily as a fumigant in replacement of methyl bromide, but it has the potential to contribute significantly to the global warming. This article introduces SO(2)F(2) in the physicochemical properties, the current uses in agriculture and industry, the toxicological data, and the environmental implications on the basis of its environmental properties. The health hazards of SO(2)F(2) and its probable decomposition products were also evaluated based on their occupational exposure limits and possible exposure sources. The resident and occupational exposure assessment was further discussed to understand seriousness of risk caused by SO(2)F(2) and its decomposition products.

  14. Copper bromide vapour laser with an output pulse duration of up to 320 ns

    Energy Technology Data Exchange (ETDEWEB)

    Gubarev, F A; Fedorov, K V; Evtushenko, G S [National Research Tomsk Polytechnic University, Tomsk (Russian Federation); Fedorov, V F; Shiyanov, D V [V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

    2016-01-31

    We report the development of a copper bromide vapour laser with an output pulse duration of up to 320 ns. To lengthen the pulse, the discharge current was limited using a compound switch comprising a pulsed hydrogen thyratron and a tacitron. This technique permits limiting the excitation of the working levels at the initial stage of the discharge development to lengthen the inversion lifetime. The longest duration of a laser pulse was reached in tubes 25 and 50 mm in diameter for a pulse repetition rate of 2 – 4 kHz. (lasers and laser beams)

  15. Holographic Measurement of the Diffusion Coefficient of Lithium Bromide in Aqueous Solution

    Science.gov (United States)

    Hattori, Masaru; Aoki, Kazuo; Yamada, Shuichi; Okubo, Takahiro

    About 90 points of diffusion coefficient of lithium bromide (LiBr) in aqueous solution were measured by holographic interferometry in the temperature range of 20∼50°C and the concentration range of 0.4∼55mass%. A correlation among concentration, temperature and diffusion coefficients was done, and an empirical equation to calculate the diffusion coefficient in the concentration and the temperature ranges mentioned above was proposed. Differences between experimental values and correlated expression were almost within±2%. Accuracy of the measured diffusion coefficients was discussed and the measurements are shown to be made within error of ±6.8%.

  16. Solution NMR structural study of a mixed aggregate of N-lithium triphenylphosphazene and lithium bromide.

    Science.gov (United States)

    Fernández, Ignacio; Davidson, Matthew G; Price, Richard D; Ortiz, Fernando López

    2009-04-07

    The toluene solution structure of an N-lithio(triphenyl)phosphazene (Ph(3)PNLi) mixed aggregate with lithium bromide (LiBr), 5, has been elucidated for the first time based on multinuclear magnetic resonance measurements ((1)H, (6)Li, (7)Li, (13)C and (31)P). The structure consist of two dimers [Li(mu-Z)](2) (Z= Br, NPR(3)) linked through LiX (X= N, Br) bridges. This arrangement is a cubane-like structure analogous to that found in the solid-state.

  17. Catalytic Reduction of Alkyl and Aryl Bromides Using Propan-2-ol.

    Science.gov (United States)

    Haibach, Michael C; Stoltz, Brian M; Grubbs, Robert H

    2017-11-20

    Milstein's complex, (PNN)RuHCl(CO), catalyzes the efficient reduction of aryl and alkyl halides under relatively mild conditions by using propan-2-ol and a base. Sterically hindered tertiary and neopentyl substrates are reduced efficiently, as well as more functionalized aryl and alkyl bromides. The reduction process is proposed to occur by radical abstraction/hydrodehalogenation steps at ruthenium. Our research represents a safer and more sustainable alternative to typical silane, lithium aluminium hydride, and tin-based conditions for these reductions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Research on Wheat Straw Pulping with Ionic Liquid 1-Ethyl-3-Methylimidazole Bromide

    Directory of Open Access Journals (Sweden)

    Wei Song

    2016-12-01

    Full Text Available In this paper, the pulping process of wheat straw using ionic liquid 1-ethyl-3-methylimidazolium bromide ([Emim]Br as the digestion liquor is presented. The influence of pulping conditions on the pulp yield are analysed by single-factor and orthogonal experiments, and optimum pulping conditions are obtained. The average pulp yield reaches 44 %, and the average recovery rate of ionic liquid is 93.5 %. The XRD pattern shows no obvious change in the crystal structure of the wheat straw cellulose. Additionally, the SEM image illustrates that there are many fine fibres in the pulp and the spaces between the fibres are large.

  19. Electron irradiation effects on optical properties of semiorganic antimony thiourea bromide monohydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mahesha Upadhya, K., E-mail: mahesh.upadhya@yahoo.co [Department of Physics, National Institute of Technology Karnataka, Surathkal, P.O. Srinivasnagar, Karnataka 575025 (India); Udayashankar, N.K. [Department of Physics, National Institute of Technology Karnataka, Surathkal, P.O. Srinivasnagar, Karnataka 575025 (India)

    2010-12-15

    Antimony thiourea bromide monohydrate (ATBM) single crystals were grown by solution growth technique at room temperature for the first time. The UV-vis, FT-IR and fluorescence spectra were recorded and electron irradiation effects on these properties were studied. The optical absorption edge of the UV-vis spectrum shifts towards lower wavelength with the increase of irradiation. The fluorescence quantum yield is increased for electron irradiated ATBM crystals. The FT-IR analysis shows that the water of crystallization is weakly bonded in as-grown and electron irradiated ATBM crystals.

  20. Soil CO2 efflux of a larch forest in northern Japan

    Directory of Open Access Journals (Sweden)

    Y. Fujinuma

    2010-11-01

    Full Text Available We had continuously measured soil CO2 efflux (Rs in a larch forest in northern Japan at hourly intervals for the snow-free period in 2003 with an automated chamber system and partitioned Rs into heterotrophic respiration (Rh and autotrophic respiration (Rr by using the trench method. In addition, we applied the soil CO2 concentration gradients method to continuously measure soil CO2 profiles under snowpack in the snowy period and to partition Rs into topsoil (Oa and A horizons CO2 efflux (Ft with a depth of 0.13 m and sub-soil (C horizon CO2 efflux (Fc. We found that soil CO2 effluxes were strongly affected by the seasonal variation of soil temperature but weakly correlated with soil moisture, probably because the volumetric soil moisture (30–40% at 95% confidence interval was within a plateau region for root and microbial activities. The soil CO2 effluxes changed seasonally in parallel with soil temperature in topsoil with the peak in late summer. On the other hand, the contribution of Rr to Rs was the largest at about 50% in early summer, when canopy photosynthesis and plant growth were more active. The temperature sensitivity (Q10 of Rr peaked in June. Under snowpack, Rs was stable until mid-March and then gradually increased with snow melting. Rs summed up to 79 gC m−2 during the snowy season for 4 months. The annual Rs was determined at 934 gC m−2 y−1 in 2003, which accounted for 63% of ecosystem respiration. The annual contributions of Rh and Rs to Rs were 57% and 43%, respectively. Based on the gradient approach, Rs was partitioned vertically into litter (Oi and Oe horizons with a depth of 0.01–0.02 m, topsoil and sub-soil respirations with proportions of 6, 72 and 22%, respectively, on an annual basis. The vertical distribution of CO2 efflux was consistent with those of soil carbon and root biomass.

  1. Conessine as a novel inhibitor of multidrug efflux pump systems in Pseudomonas aeruginosa.

    Science.gov (United States)

    Siriyong, Thanyaluck; Srimanote, Potjanee; Chusri, Sasitorn; Yingyongnarongkul, Boon-Ek; Suaisom, Channarong; Tipmanee, Varomyalin; Voravuthikunchai, Supayang Piyawan

    2017-08-14

    Holarrhena antidysenterica has been employed as an ethnobotanical plant for the treatment of dysentery, diarrhoea, fever, and bacterial infections. Biological activities of the principle compound, conessine including anti-diarrhoea and anti-plasmodial effects were documented. Our previous study reported potency of Holarrhena antidysenterica extract and conessine as resistance modifying agents against extensively drug-resistant Acinetobacter baumannii. This study aimed to investigate (i) whether conessine, a steroidal alkaloid compound, could act as a resistance modifying agent against multidrug-resistant Pseudomonas aeruginosa, and (ii) whether MexAB-OprM efflux pump involved in the mechanism. Conessine combined with various antibiotics were determined for synergistic activity against P. aeruginosa PAO1 strain K767 (wild-type), K1455 (MexAB-OprM overexpressed), and K1523 (MexB deletion). H33342 accumulation assay was used to evaluate efflux pump inhibition while NPN uptake assay was assessed membrane permeabilization. Conessine significantly reduced MICs of all antibiotics by at least 8-fold in MexAB-OprM overexpressed strain. The levels were comparable to those obtained in wild-type strain for cefotaxime, levofloxacin, and tetracycline. With erythromycin, novobiocin, and rifampicin, MICs were 4- to 8-fold less than MICs of the wild-type strain. Loss of MexAB-OprM due to deletion of mexB affected susceptibility to almost all antibiotics, except novobiocin. Synergistic activities between other antibiotics (except novobiocin) and conessine observed in MexB deletion strain suggested that conessine might inhibit other efflux systems present in P. aeruginosa. Inhibition of H33342 efflux in the tested strains clearly demonstrated that conessine inhibited MexAB-OprM pump. In contrast, the mode of action as a membrane permeabilizer was not observed after treatment with conessine as evidenced by no accumulation of 1-N-phenylnaphthylamine. The results suggested that

  2. Dissociation of internal energy-selected methyl bromide ion revealed from threshold photoelectron-photoion coincidence velocity imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Xiaofeng [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Zhou, Xiaoguo, E-mail: xzhou@ustc.edu.cn, E-mail: yanbing@jlu.edu.cn; Liu, Shilin [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Sun, Zhongfa [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); Liu, Fuyi; Sheng, Liusi [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Yan, Bing, E-mail: xzhou@ustc.edu.cn, E-mail: yanbing@jlu.edu.cn [Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China)

    2014-01-28

    Dissociative photoionization of methyl bromide (CH{sub 3}Br) in an excitation energy range of 10.45–16.90 eV has been investigated by using threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging. The coincident time-of-flight mass spectra indicate that the ground state X{sup 2}E of CH{sub 3}Br{sup +} is stable, and both A{sup 2}A{sub 1} and B{sup 2}E ionic excited states are fully dissociative to produce the unique fragment ion of CH{sub 3}{sup +}. From TPEPICO 3D time-sliced velocity images of CH{sub 3}{sup +} dissociated from specific state-selected CH{sub 3}Br{sup +} ion, kinetic energy release distribution (KERD) and angular distribution of CH{sub 3}{sup +} fragment ion are directly obtained. Both spin-orbit states of Br({sup 2}P) atom can be clearly observed in fast dissociation of CH{sub 3}Br{sup +}(A{sup 2}A{sub 1}) ion along C–Br rupture, while a KERD of Maxwell-Boltzmann profile is obtained in dissociation of CH{sub 3}Br{sup +}(B{sup 2}E) ion. With the aid of the re-calculated potential energy curves of CH{sub 3}Br{sup +} including spin-orbit coupling, dissociation mechanisms of CH{sub 3}Br{sup +} ion in A{sup 2}A{sub 1} and B{sup 2}E states along C–Br rupture are revealed. For CH{sub 3}Br{sup +}(A{sup 2}A{sub 1}) ion, the CH{sub 3}{sup +} + Br({sup 2}P{sub 1/2}) channel is occurred via an adiabatic dissociation by vibration, while the Br({sup 2}P{sub 3/2}) formation is through vibronic coupling to the high vibrational level of X{sup 2}E state followed by rapid dissociation. C–Br bond breaking of CH{sub 3}Br{sup +}(B{sup 2}E) ion can occur via slow internal conversion to the excited vibrational level of the lower electronic states and then dissociation.

  3. Chemical Kinetics Database

    Science.gov (United States)

    SRD 17 NIST Chemical Kinetics Database (Web, free access)   The NIST Chemical Kinetics Database includes essentially all reported kinetics results for thermal gas-phase chemical reactions. The database is designed to be searched for kinetics data based on the specific reactants involved, for reactions resulting in specified products, for all the reactions of a particular species, or for various combinations of these. In addition, the bibliography can be searched by author name or combination of names. The database contains in excess of 38,000 separate reaction records for over 11,700 distinct reactant pairs. These data have been abstracted from over 12,000 papers with literature coverage through early 2000.

  4. Thermal kinetic inductance detector

    Science.gov (United States)

    Cecil, Thomas; Gades, Lisa; Miceli, Antonio; Quaranta, Orlando

    2016-12-20

    A microcalorimeter for radiation detection that uses superconducting kinetic inductance resonators as the thermometers. The detector is frequency-multiplexed which enables detector systems with a large number of pixels.

  5. Geometry-controlled kinetics.

    Science.gov (United States)

    Bénichou, O; Chevalier, C; Klafter, J; Meyer, B; Voituriez, R

    2010-06-01

    It has long been appreciated that the transport properties of molecules can control reaction kinetics. This effect can be characterized by the time it takes a diffusing molecule to reach a target-the first-passage time (FPT). Determining the FPT distribution in realistic confined geometries has until now, however, seemed intractable. Here, we calculate this FPT distribution analytically and show that transport processes as varied as regular diffusion, anomalous diffusion, and diffusion in disordered media and fractals, fall into the same universality classes. Beyond the theoretical aspect, this result changes our views on standard reaction kinetics and we introduce the concept of 'geometry-controlled kinetics'. More precisely, we argue that geometry-and in particular the initial distance between reactants in 'compact' systems-can become a key parameter. These findings could help explain the crucial role that the spatial organization of genes has in transcription kinetics, and more generally the impact of geometry on diffusion-limited reactions.

  6. Fundamentals of enzyme kinetics.

    Science.gov (United States)

    Seibert, Eleanore; Tracy, Timothy S

    2014-01-01

    This chapter provides a general introduction to the kinetics of enzyme-catalyzed reactions, with a focus on drug-metabolizing enzymes. A prerequisite to understanding enzyme kinetics is having a clear grasp of the meanings of "enzyme" and "catalysis." Catalysts are reagents that can increase the rate of a chemical reaction without being consumed in the reaction. Enzymes are proteins that form a subset of catalysts. These concepts are further explored below.

  7. Electrochemical kinetics theoretical aspects

    CERN Document Server

    Vetter, Klaus J

    1967-01-01

    Electrochemical Kinetics: Theoretical Aspects focuses on the processes, methodologies, reactions, and transformations in electrochemical kinetics. The book first offers information on electrochemical thermodynamics and the theory of overvoltage. Topics include equilibrium potentials, concepts and definitions, electrical double layer and electrocapillarity, and charge-transfer, diffusion, and reaction overvoltage. Crystallization overvoltage, total overvoltage, and resistance polarization are also discussed. The text then examines the methods of determining electrochemical reaction mechanisms

  8. Development of an Activated Carbon-Based Electrode for the Capture and Rapid Electrolytic Reductive Debromination of Methyl Bromide from Postharvest Fumigations.

    Science.gov (United States)

    Li, Yuanqing; Liu, Chong; Cui, Yi; Walse, Spencer S; Olver, Ryan; Zilberman, David; Mitch, William A

    2016-10-18

    Due to concerns surrounding its ozone depletion potential, there is a need for technologies to capture and destroy methyl bromide (CH 3 Br) emissions from postharvest fumigations applied to control agricultural pests. Previously, we described a system in which CH 3 Br fumes vented from fumigation chambers could be captured by granular activated carbon (GAC). The GAC was converted to a cathode by submergence in a high ionic strength solution and connection to the electrical grid, resulting in reductive debromination of the sorbed CH 3 Br. The GAC bed was drained and dried for reuse to capture and destroy CH 3 Br fumes from the next fumigation. However, the loose GAC particles and slow kinetics of this primitive electrode necessitated improvements. Here, we report the development of a cathode containing a thin layer of small GAC particles coating carbon cloth as a current distributor. Combining the high sorption potential of GAC for CH 3 Br with the conductivity of the carbon cloth current distributor, the cathode significantly lowered the total cell resistance and achieved 96% reductive debromination of CH 3 Br sorbed at 30% by weight to the GAC within 15 h at -1 V applied potential vs standard hydrogen electrode, a time scale and efficiency suitable for postharvest fumigations. The cathode exhibited stable performance over 50 CH 3 Br capture and destruction cycles. Initial cost estimates indicate that this technique could treat CH 3 Br fumes at ∼$5/kg, roughly one-third of the cost of current alternatives.

  9. Shape-directing role of cetyltrimethylammonium bromide in the green synthesis of Ag-nanoparticles using Neem (Azadirachta indica) leaf extract.

    Science.gov (United States)

    Khan, Zaheer; Hussain, Javed Ijaz; Hashmi, Athar Adil

    2012-06-15

    The shape-directing role of cetyltrimethylammonium bromide, CTAB, is reported to the green synthesis of Ag-nanoparticles for the first time using Neem (Azadirachta indica) leaf extract. UV-vis spectroscopy, transmission electron microscopy (TEM), and selected area electron diffraction (SAED) patterns were used to monitor the growth kinetics, morphology and crystalline nature of Ag-nanoparticles, respectively. It was observed that the growths of Ag-nanoparticles are stopped within 40 min of reaction time. The Ag-nanoparticles are polydispersed spherical and exhibiting an interesting triangle, flat, plate-like hexagonal and some irregular morphology in presence of different [CTAB]. Hexagonal particles aggregated in a systematic manor, leads to produce a fine tiles-like arrangement of Ag-nanoparticles with dimensions between 10 and 37 nm. The nature of reaction-time curves to the reduction of Ag(+) ions by Neem leaf extract are much different than those observed by us in our earlier studies using different bio-reductants. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. New inorganic (an)ion exchangers with a higher affinity for arsenate and a competitive removal capacity towards fluoride, bromate, bromide, selenate, selenite, arsenite and borate

    KAUST Repository

    Chubar, Natalia

    2011-12-01

    Highly selective materials and effective technologies are needed to meet the increasingly stronger drinking water standards for targeted ionic species. Inorganic ion exchangers based on individual and mixed-metal hydrous oxides (or mixed adsorbents that contain inorganic ion exchangers in their composition) are adsorptive materials that are capable of lowering the concentrations of anionic contaminants, such as H 2AsO 4 -, H 3AsO 3, F -, Br -, BrO 3 -, HSeO 4 -, HSeO 3 - and H 3BO 3, to 10 μg/L or less. To achieve a higher selectivity towards arsenate, a new ion exchanger based on Mg-Al hydrous oxides was developed by a novel, cost-effective and environmentally friendly synthesis method via a non-traditional (alkoxide-free) sol-gel approach. The exceptional adsorptive capacity of the Mg-Al hydrous oxides towards H 2AsO 4 - (up to 200 mg[As]/gdw) is due to the high affinity of this sorbent towards arsenate (steep equilibrium isotherms) and its fast adsorption kinetics. Because of the mesoporous (as determined by N 2 adsorption and SEM) and layered (as determined by XRD and FTIR) structure of the ion-exchange material as well as the abundance of anion exchange sites (as determined by XPS and potentiometric titration) on its surface the material demonstrated very competitive (or very high) removal capacity towards other targeted anions, including fluoride, bromide, bromate, selenate, selenite, and borate. © 2011 IWA Publishing.

  11. Inhibition of the multidrug efflux pump LmrS from Staphylococcus aureus by cumin spice Cuminum cyminum.

    Science.gov (United States)

    Kakarla, Prathusha; Floyd, Jared; Mukherjee, MunMun; Devireddy, Amith R; Inupakutika, Madhuri A; Ranweera, Indrika; Kc, Ranjana; 'Shrestha, Ugina; Cheeti, Upender Rao; Willmon, Thomas Mark; Adams, Jaclyn; Bruns, Merissa; Gunda, Shravan Kumar; Varela, Manuel F

    2017-04-01

    Staphylococcus aureus is a serious causative agent of infectious disease. Multidrug-resistant strains like methicillin-resistant S. aureus compromise treatment efficacy, causing significant morbidity and mortality. Active efflux represents a major antimicrobial resistance mechanism. The proton-driven multidrug efflux pump, LmrS, actively exports structurally distinct antimicrobials. To circumvent resistance and restore clinical efficacy of antibiotics, efflux pump inhibitors are necessary, and natural edible spices like cumin are potential candidates. The mode of cumin antibacterial action and underlying mechanisms behind drug resistance inhibition, however, are unclear. We tested the hypothesis that cumin inhibits LmrS drug transport. We found that cumin inhibited bacterial growth and LmrS ethidium transport in a dosage-dependent manner. We demonstrate that cumin is antibacterial toward a multidrug-resistant host and that resistance modulation involves multidrug efflux inhibition.

  12. [Comparative effects of terbutaline sulphate and ipratropium bromide on the respiratory system (author's transl)].

    Science.gov (United States)

    Villate Navarro, J I; Sobradillo Peña, V; Atxotequi Iaraoligoitia, V; Salaverri Nalda, A; Orive Martínez, C

    1980-04-10

    Bronchodilator action of two pharmacologically different drugs have been compared. Ipratropium bromide (Sch 1000) is a synthetic atropine derivative and terbutaline sulphate is a beta-stimulating agent. Twelve asthmatic patients and eight patients with chronic bronquitis received terbutaline 0.50 mg. and ipratropium 0.04 mg by aerosol inhalation. Both drugs were given at random on a consecutive-day schedule. All patients were clinically stable before treatment (basal FEV/VC less than 60 percent). Total lung capacity (TLC) forced expiratory volume (FEV), SRaw, and V'/V curves before and at 15, 60, 120, and 240 minutes after the produce administration were registered. Presence of side-effects was also checked. An intensive bronchodilator action was observed either after inhalation of ipratropium bromide or terbutaline, but statistical studies showed no significant differences between both drugs in relation to intensity and duration of their actions. Sch 1000 caused similar bronchodilator effects in all cases; a more intense effect in patients with chronic bronchitis could not be noticed. Evaluation of V'/V curve, and especially its relation to a same pulmonary volume, pointed out that both drugs act upon small respiratory airways. Advance side-effects were not present.

  13. Impact of Wildfire Emissions on Chloride and Bromide Depletion in Marine Aerosol Particles.

    Science.gov (United States)

    Braun, Rachel A; Dadashazar, Hossein; MacDonald, Alexander B; Aldhaif, Abdulamonam M; Maudlin, Lindsay C; Crosbie, Ewan; Aghdam, Mojtaba Azadi; Hossein Mardi, Ali; Sorooshian, Armin

    2017-08-15

    This work examines particulate chloride (Cl-) and bromide (Br-) depletion in marine aerosol particles influenced by wildfires at a coastal California site in the summers of 2013 and 2016. Chloride exhibited a dominant coarse mode due to sea salt influence, with substantially diminished concentrations during fire periods as compared to nonfire periods. Bromide exhibited a peak in the submicrometer range during fire and nonfire periods, with an additional supermicrometer peak in the latter periods. Chloride and Br- depletions were enhanced during fire periods as compared to nonfire periods. The highest observed %Cl- depletion occurred in the submicrometer range, with maximum values of 98.9% (0.32-0.56 μm) and 85.6% (0.56-1 μm) during fire and nonfire periods, respectively. The highest %Br- depletion occurred in the supermicrometer range during fire and nonfire periods with peak depletion between 1.8-3.2 μm (78.8% and 58.6%, respectively). When accounting for the neutralization of sulfate by ammonium, organic acid particles showed the greatest influence on Cl- depletion in the submicrometer range. These results have implications for aerosol hygroscopicity and radiative forcing in areas with wildfire influence owing to depletion effects on composition.

  14. Structural, vibrational and thermal characterization of phase transformation in L-histidinium bromide monohydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Moura, G.M. [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil); Universidade Federal do Sul e Sudeste do Pará, ICEN, Marabá, PA 68505-080 (Brazil); Carvalho, J.O. [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil); Instituto Federal do Tocantins, Araguaína, TO, 77.826-170 (Brazil); Silva, M.C.D.; Façanha Filho, P.F. [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil); Santos, A.O. dos, E-mail: adenilson1@gmail.com [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil)

    2015-09-01

    L-Histidinium bromide monohydrate (LHBr) single crystal is a nonlinear optical material. In this work the high temperature phase transformation and the thermal stability of single crystals of LHBr was investigated by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry and Raman spectroscopy. The results showed the LHBr phase transformation of orthorhombic (P2{sub 1}2{sub 1}2{sub 1}) to monoclinic system (P 1 2 1) at 120 °C, with the lattice parameters a = 12.162(1) Å, b = 16.821(2) Å, c = 19.477(2) Å and β = 108.56(2)°. These techniques are complementary and confirm the structural phase transformation due to loss water of crystallization. - Highlights: • -histidinium bromide single crystal was grown by slow evaporation technique. • X-ray diffraction characterize the high-temperature phase transformation. • The structural phase transformation occur due to loss of water of crystallization. • The LHBr thermal expansion coefficients exhibit an anisotropic behavior.

  15. A Vertical Falling Film Type of Absorber and Generator for Lithium Bromide Aqueous Solutions

    Science.gov (United States)

    Matsuda, Akira; Hada, Kunihiko; Kawamura, Teruo

    Experiments on evaporation and absorption for lithium bromide aqueous solutions(0-60wt%LiBr) were made in a vertical falling film type of stainless steal columm under reduced pressure, 8.0kPa. The changes of concentration and temperature in the falling film columm and the rates of absorption and evaporation were equivalent in the absorber and generator. They agreed well with the values calculated by the one-dimentional difference method using heat transfer coefficient, mass transfer coeficient and the unidirectional diffusion model. Therefore, it is guessed that a falling film type of absorber and generator may be designed by the same method. Considering the relation between heat flux and degree of superheat at heat transfer surface, and the mixing condition of lithium bromide aqueous solution in a generator, it is found that a falling film type generator is superior to a pool boiling type for a generator in absorption-type refrigerator and heat pump driven by low temperature heat source.

  16. Chemical alternatives to methyl bromide for the control of root-knot nematodes in greenhouses.

    Science.gov (United States)

    Giannakou, Ioannis O; Sidiropoulos, Artemios; Prophetou-Athanasiadou, Demetra

    2002-03-01

    The complete phase-out of methyl bromide from use in developed countries by 1 January 2005 will cause many problems in agricultural industries that are now heavily reliant on its use. Three field experiments were established to compare management tactics on tomato and cucumber in commercial greenhouses naturally infested with root-knot nematodes (Meloidogyne spp). Reduction of nematode juveniles in soil and roots to nil detection levels was observed in all plots following soil fumigation with methyl bromide. A significant reduction of nematode juveniles and root-galling index was observed in plots treated with metham-sodium, dazomet and 1,3-dichloropropene compared with the control and plots treated with non-fumigant nematicides. Reduction of the nematode population led to an increase in fruit yield. However, data collected from the second cultivation season indicated that single control methods such as fumigant or contact nematicides alone cannot drastically decrease initial nematode population and those nematodes which escape control lead to population increase by the end of the cropping season.

  17. Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation.

    Science.gov (United States)

    Liu, Zhen; Zhang, Zhongdong; Xing, Wei; Komarneni, Sridhar; Yan, Zifeng; Gao, Xionghou; Zhou, Xiaoping

    2014-01-01

    Three kinds of HZSM-5 nanoparticles with different acidity were tailored by impregnating MgO or varying Si/Al ratios. Both the textural and acidic properties of the as-prepared nanoparticles were characterized by nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature-programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR or Py-FTIR). It was found that the intensity of Lewis acid sites with weak strength was enhanced by impregnating MgO or reducing Al concentration, and such an enhancement could be explained by the formation of Mg(OH)(+) or charge unbalance of the MgO framework on the surface of HZSM-5 support. The effect of HZSM-5 nanoparticles' acidity on methyl bromide dehydrobromination as catalyst was evaluated. As the results, MgHZ-360 catalyst with the highest concentration of Lewis acid sites showed excellent stability, which maintained methyl bromide conversion of up 97% in a period of 400 h on stream. Coke characterization by BET measurements and TGA/DTA and GC/MS analysis revealed that polymethylated naphthalenes species were formed outside the channels of the catalyst with higher acid intensity and higher Brønsted acid concentration during the initial period of reaction, while graphitic carbon formed in the channels of catalyst with lower acid intensity and higher Lewis acid concentration during the stable stage.

  18. Mesoporous Silica Formation by Block Copolymers and Cetyltrimethylammonium Bromide as Structure Control Agent

    Directory of Open Access Journals (Sweden)

    Mohamad Ali Semsarzadeh

    2013-01-01

    Full Text Available Block copolymers and cetyltrimethylammonium bromide were used as templates in nano silica structure formation like MCM-41Mobil Composition of Matter, SBA16 Santa Barbara Amorphous and a new compound namely SPB  silicone mesoporous particles, prepared by sol-gel method using PPG-PEG-PPG block copolymer to compare the porosity and regularity of the products together. In this work tetraethylorthosilicate  TEOS, as silica source and alcohol as surface modifying agent were used because of having the main advantage, compared to an ionic template such as etyltrimethylammonium bromide, in producing larger pores  and thicker walls for holding larger catalytic molecules in their pores or increasing  their resistance towards fragmentation. In order to study the copolymer as a template,  SPB structure was prepared and compared with SBA16 which was found to have  broader  pore-size  distribution  and  smaller  specifc  surface  area.  Using  alcohol  in particle production resulted in higher formation rate of micelles with improved  morphology. Nitrogen adsorption-desorption, X-ray diffraction and electron scanning  microscopy confrmed the mesoporous structure and regularity of these synthesized  materials. Finally a mechanism is proposed for the formation of these structures.

  19. Surface Electronic Structure of Hybrid Organo Lead Bromide Perovskite Single Crystals

    KAUST Repository

    Komesu, Takashi

    2016-08-24

    The electronic structure and band dispersion of methylammonium lead bromide, CH3NH3PbBr3, has been investigated through a combination of angle-resolved photoemission spectroscopy (ARPES) and inverse photoemission spectroscopy (IPES), as well as theoretical modeling based on density functional theory. The experimental band structures are consistent with the density functional calculations. The results demonstrate the presence of a dispersive valence band in MAPbBr3 that peaks at the M point of the surface Brillouin zone. The results also indicate that the surface termination of the CH3NH3PbBr3 is the methylammonium bromide (CH3NH3Br) layer. We find our results support models that predict a heavier hole effective mass in the region of -0.23 to -0.26 me, along the Γ (surface Brillouin center) to M point of the surface Brillouin zone. The surface appears to be n-type as a result of an excess of lead in the surface region. © 2016 American Chemical Society.

  20. Health effects associated with sulfuryl fluoride and methyl bromide exposure among structural fumigation workers.

    Science.gov (United States)

    Calvert, G M; Mueller, C A; Fajen, J M; Chrislip, D W; Russo, J; Briggle, T; Fleming, L E; Suruda, A J; Steenland, K

    1998-01-01

    OBJECTIVES: This study assessed the health effects associated with occupational exposure to methyl bromide and sulfuryl fluoride among structural fumigation workers. METHODS: A cross-sectional study of 123 structural fumigation workers and 120 referents in south Florida was conducted. Nerve conduction, vibration, neurobehavioral, visual, olfactory, and renal function testing was included. RESULTS: The median lifetime duration of methyl bromide and sulfuryl fluoride exposure among workers was 1.20 years and 2.85 years, respectively. Sulfuryl fluoride exposure over the year preceding examination was associated with significantly reduced performance on the Pattern Memory Test and on olfactory testing. In addition, fumigation workers had significantly reduced performance on the Santa Ana Dexterity Test of the dominant hand and a nonsignificantly higher prevalence of carpal tunnel syndrome than did the referents. CONCLUSIONS: Occupational sulfuryl fluoride exposures may be associated with subclinical effects on the central nervous system, including effects on olfactory and some cognitive functions. However, no widespread pattern of cognitive deficits was observed. The peripheral nerve effects were likely caused by ergonomic stresses experienced by the fumigation workers. PMID:9842373

  1. Modeling Water Flow and Bromide Transport in a Two-Scale-Structured Lignitic Mine Soil

    Science.gov (United States)

    Dusek, J.; Gerke, H. H.; Vogel, T.; Maurer, T.; Buczko, U.

    2008-12-01

    Two-dimensional single- and dual-permeability simulations are used to analyze water and solute fluxes in heterogeneous lignitic mine soil at a forest-reclaimed mine spoil heap. The soil heterogeneity on this experimental site "Barenbrucker Hohe" resulted from inclined dumping structures and sediment mixtures that consist of sand with lignitic dust and embedded lignitic fragments. Observations on undisturbed field suction- cell lysimeters including tracer experiments revealed funneling-type preferential flow with lateral water and bromide movement along inclined sediment structures. The spatial distribution of soil structures and fragment distributions was acquired by a digital camera and identified by a supervised classification of the digital profile image. First, a classical single-domain modeling approach was proposed with spatially variable scaling factors inferred from image analyses. In the next step, a two-continuum scenario was constructed to examine additional effects of nonequilibrium on the flow regime. The scaling factors used for the preferential flow domain are here obtained from the gradient of the grayscale images. So far, the single domain scenarios failed to predict the bromide leaching patterns although water effluent could be described. Dual-permeability model allows the incorporation of structural effects and can be used as a tool to further testing other approaches that account for structure effects. The numerical study suggests that additional experiments are required to obtain better understanding of the highly complex transport processes on this experimental site.

  2. Titrimetric and spectrophotometric determination of doxycycline hyclate using bromate-bromide, methyl orange and indigo carmine

    Directory of Open Access Journals (Sweden)

    Pavagada Jagannathamurthy Ramesh

    2010-07-01

    Full Text Available One titrimetric and two indirect spectrophotometric methods are described for the determination of doxycycline hyclate (DCH in bulk drug and in its formulations. The methods use bromate-bromide, methyl orange and indigo carmine as reagents. In titrimetry (method A, DCH is treated with a known excess of bromate- -bromide mixture in acid medium and the residual bromine is back titrated iodometrically after the reaction between DCH and in situ bromine is ensured to be complete. In spectrophotometric methods, the excess of bromine is estimated by treating with a fixed amount of either methyl orange (method B or indigo carmine (method C and measuring the change in absorbance either at 520 or 610 nm. Titrimetric method is applicable over 1-8 mg range and the calculations are based on a 1:2 (DCH:bromate stoichiometric ratio. In spectrophotometry, the calibration graphs were found to be linear over 0.25-1.25 and 1.0-5.0 μg mL-1 for method B and C, respectively, with corresponding molar absorptivity values of 2.62×105 and 6.97×104 L mol-1 cm-1. The accuracy and precision of the assays were determined by computing the intra-day and inter-day variations at three different levels of DCH.

  3. Sociology in Global Environmental Governance? Neoliberalism, Protectionism and the Methyl Bromide Controversy in the Montreal Protocol

    Directory of Open Access Journals (Sweden)

    Brian J. Gareau

    2017-10-01

    Full Text Available Sociological studies of global agriculture need to pay close attention to the protectionist aspects of neoliberalism at the global scale of environmental governance. With agri-food studies in the social sciences broadening interrogations of the impact of neoliberalism on agri-food systems and their alternatives, investigating global environmental governance (GEG will help reveal its impacts on the global environment, global science/knowledge, and the potential emergence of ecologically sensible alternatives. It is argued here that as agri-food studies of neoliberalism sharpen the focus on these dimensions the widespread consequences of protectionism of US agri-industry in GEG will become better understood, and the solutions more readily identifiable. This paper illustrates how the delayed phase out of the toxic substance methyl bromide in the Montreal Protocol exemplifies the degree to which the US agri-industry may be protected at the global scale of environmental governance, thus prolonging the transition to ozone-friendly alternatives. Additionally, it is clear that protectionism has had a significant impact on the dissemination and interpretation of science/knowledge of methyl bromide and its alternatives. Revealing the role that protectionism plays more broadly in the agriculture/environmental governance interface, and its oftentimes negative impacts on science and potential alternatives, can shed light on how protectionism can be made to serve ends that are at odds with environmental protection.

  4. Ab initio study of methyl-bromide photodissociation in the à band

    Science.gov (United States)

    Escure, Christelle; Leininger, Thierry; Lepetit, Bruno

    2009-06-01

    We performed a theoretical study of the photodissociation dynamics of CH3Br in the à band using a wave packet propagation technique on coupled ab initio potential energy curves. The present model involves the Q31 and Q11 excited states which can be populated from the ground state by a perpendicular transition and which are correlated at large methyl-bromide distance to the ground bromide spin-orbit state, as well as the Q30 and 4E states which can be excited by a parallel and perpendicular transition (respectively) and both correlate to excited Br∗ spin-orbit state. The model provides absorption cross sections and branching ratios in excellent agreement with experimental results. Due to weak spin-orbit interaction, the Q11 state is the dominant contributor to the absorption cross section, except for the red wing of the band where Q30 and Q31 states have significant absorption. However, spin-orbit coupling is strong enough to induce nonadiabatic transitions between the Q31 and Q11 states during the dissociation process which should be experimentally detectable in the alignment properties of the fragments. Nonadiabatic transitions at the conical intersection between Q30 and Q11 are shown to play a minor role in this system.

  5. Evaluation of Five Simulation Models for Predicting Aldicarb and Bromide Behavior Under Field Conditions

    Science.gov (United States)

    Pennell, K. D.; Hornsby, A. G.; Jessup, R. E.; Rao, P. S. C.

    1990-11-01

    Five pesticide simulation models (Chemical Movement in Layered Soils (CLMS), Method of Underground Solute Evaluation (MOUSE), Pesticide Root Zone Model (PRZM), Groundwater Leading Effects of Agriculture Management Systems (GLEAMS), and Leaching Estimation and Chemistry Model-Pesticides (LEACHMP)) were evaluated using data for the transport and transformation of aldicarb and bromide in the unsaturated zone. Although these models have been tested separately, to date no effort has been made to evaluate all of them using a comprehensive data set from a single field study. Model performance was evaluated based on their ability to predict: the depth of solute center of mass, solute dissipation, and solute concentration distributions within the soil profile. GLEAMS and MOUSE underestimated bromide and aldicarb dissipation, while the other models provided satisfactory predictions of both solute center of mass and pesticide degradation. None of the models accurately described measured solute concentration distributions. Recommendations are made for the selection and use of the models based on objective and subjective criteria including graphical analysis, objective functions, intended model use, and the difficulty in obtaining model input data.

  6. Iodide, bromide, and ammonium in hydraulic fracturing and oil and gas wastewaters: environmental implications.

    Science.gov (United States)

    Harkness, Jennifer S; Dwyer, Gary S; Warner, Nathaniel R; Parker, Kimberly M; Mitch, William A; Vengosh, Avner

    2015-02-03

    The expansion of unconventional shale gas and hydraulic fracturing has increased the volume of the oil and gas wastewater (OGW) generated in the U.S. Here we demonstrate that OGW from Marcellus and Fayetteville hydraulic fracturing flowback fluids and Appalachian conventional produced waters is characterized by high chloride, bromide, iodide (up to 56 mg/L), and ammonium (up to 420 mg/L). Br/Cl ratios were consistent for all Appalachian brines, which reflect an origin from a common parent brine, while the I/Cl and NH4/Cl ratios varied among brines from different geological formations, reflecting geogenic processes. There were no differences in halides and ammonium concentrations between OGW originating from hydraulic fracturing and conventional oil and gas operations. Analysis of discharged effluents from three brine treatment sites in Pennsylvania and a spill site in West Virginia show elevated levels of halides (iodide up to 28 mg/L) and ammonium (12 to 106 mg/L) that mimic the composition of OGW and mix conservatively in downstream surface waters. Bromide, iodide, and ammonium in surface waters can impact stream ecosystems and promote the formation of toxic brominated-, iodinated-, and nitrogen disinfection byproducts during chlorination at downstream drinking water treatment plants. Our findings indicate that discharge and accidental spills of OGW to waterways pose risks to both human health and the environment.

  7. Efficient Sky-Blue Perovskite Light-Emitting Devices Based on Ethylammonium Bromide Induced Layered Perovskites.

    Science.gov (United States)

    Wang, Qi; Ren, Jie; Peng, Xue-Feng; Ji, Xia-Xia; Yang, Xiao-Hui

    2017-09-06

    Low-dimensional organometallic halide perovskites are actively studied for the light-emitting applications due to their properties such as solution processability, high luminescence quantum yield, large exciton binding energy, and tunable band gap. Introduction of large-group ammonium halides not only serves as a convenient and versatile method to obtain layered perovskites but also allows the exploitation of the energy-funneling process to achieve a high-efficiency light emission. Herein, we investigate the influence of the addition of ethylammonium bromide on the morphology, crystallite structure, and optical properties of the resultant perovskite materials and report that the phase transition from bulk to layered perovskite occurs in the presence of excess ethylammonium bromide. On the basis of this strategy, we report green perovskite light-emitting devices with the maximum external quantum efficiency of ca. 3% and power efficiency of 9.3 lm/W. Notably, blue layered perovskite light-emitting devices with the Commission Internationale de I'Eclairage coordinates of (0.16, 0.23) exhibit the maximum external quantum efficiency of 2.6% and power efficiency of 1 lm/W at 100 cd/m2, representing a large improvement over the previously reported analogous devices.

  8. Engineering bacterial efflux pumps for solar-powered bioremediation of surface waters.

    Science.gov (United States)

    Kapoor, Vikram; Wendell, David

    2013-05-08

    Antibiotics are difficult to selectively remove from surface waters by present treatment methods. Bacterial efflux pumps have evolved the ability to discriminately expel antibiotics and other noxious agents via proton and ATP driven pathways. Here, we describe light-dependent removal of antibiotics by engineering the bacterial efflux pump AcrB into a proteovesicle system. We have created a chimeric protein with the requisite proton motive force by coupling AcrB to the light-driven proton pump Delta-rhodopsin (dR) via a glycophorin A transmembrane domain. This creates a solar powered protein material capable of selectively capturing antibiotics from bulk solutions. Using environmental water and direct sunlight, our AcrB-dR vesicles removed almost twice as much antibiotic as the treatment standard, activated carbon. Altogether, the AcrB-dR system provides an effective means of extracting antibiotics from surface waters as well as potential antibiotic recovery through vesicle solubilization.

  9. Identification of a Staphylococcus aureus Efflux Pump Regulator Using a DNA-Protein Affinity Technique.

    Science.gov (United States)

    Truong-Bolduc, Que Chi; Hooper, David C

    2018-01-01

    In this chapter, we describe the step-by-step identification of a putative regulator protein and demonstrate the function of this protein as a repressor of the expression of a specific efflux pump, causing resistance to quinolones in Staphylococcus aureus. We show that the knockout gene mutant has an increase in transcript levels of the target efflux pump when compared to that of the S. aureus parental strain RN6390. We provide a detailed protocol that includes the identification of the DNA-binding transcriptional regulatory protein from S. aureus cell extracts using DNA sequences linked to magnetic beads. In addition, we describe the real-time qRT-PCR assays and MIC testing to evaluate the effects of the regulator on S. aureus drug resistance phenotype.

  10. Winter carbon dioxide effluxes from Arctic ecosystems: An overview and comparison of methodologies

    DEFF Research Database (Denmark)

    Björkman, M.P.; Morgner, E.; Cooper, E.J.

    2010-01-01

    The winter CO2 efflux from subnivean environments is an important component of annual C budgets in Arctic ecosystems and consequently makes prediction and estimations of winter processes as well as incorporations of these processes into existing models important. Several methods have been used...... for estimating winter CO2 effluxes involving different assumptions about the snowpack, all aiming to quantify CO2 production. Here, four different methods are compared and discussed: (1) measurements with a chamber on the snow surface, Fsnow, (2) chamber measurements directly on the soil, Fsoil, after snow...... removal, (3) diffusion measurements, F2-point, within the snowpack, and (4) a trace gas technique, FSF6, with multiple gas sampling within the snowpack. According to measurements collected from shallow and deep snow cover in High Arctic Svalbard and subarctic Sweden during the winter of 2007...

  11. Efflux in fungi: la pièce de résistance.

    Directory of Open Access Journals (Sweden)

    Jeffrey J Coleman

    2009-06-01

    Full Text Available Pathogens must be able to overcome both host defenses and antimicrobial treatment in order to successfully infect and maintain colonization of the host. One way fungi accomplish this feat and overcome intercellular toxin accumulation is efflux pumps, in particular ATP-binding cassette transporters and transporters of the major facilitator superfamily. Members of these two superfamilies remove many toxic compounds by coupling transport with ATP hydrolysis or a proton gradient, respectively. Fungal genomes encode a plethora of members of these families of transporters compared to other organisms. In this review we discuss the role these two fungal superfamilies of transporters play in virulence and resistance to antifungal agents. These efflux transporters are responsible not only for export of compounds involved in pathogenesis such as secondary metabolites, but also export of host-derived antimicrobial compounds. In addition, we examine the current knowledge of these transporters in resistance of pathogens to clinically relevant antifungal agents.

  12. Use and engineering of efflux pumps for the export of olefins in microbes

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, Aindrila [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States)

    2016-07-14

    The scope of the project is to investigate efflux pump systems in engineered host microorganisms, such as E. coli, and develop a pump engineered to export a target compound. To initiate the project in coordination with other TOTAL driven projects, the first target compound to be studied was 1-hexene. However, we were investigating other chemicals as Styrene. The main goal of the project was to generate a set of optimized efflux pump systems for microorganisms (E. coli and Streptomyces or other host) engineered to contain biosynthetic pathways to export large titers of target compounds that are toxic (or accumulate and push back biosynthesis) to the host cell. An optimized microbial host will utilize specific and efficient cell wall located pumps to extrude harmful target compounds and enable greater production of these compounds.

  13. ABCA1-dependent serum cholesterol efflux capacity inversely correlates with pulse wave velocity in healthy subjects[S

    OpenAIRE

    Favari, Elda; Ronda, Nicoletta; Adorni, Maria Pia; Zimetti, Francesca; Salvi, Paolo; Manfredini, Matteo; Bernini, Franco; Borghi, Claudio; Cicero, Arrigo F. G.

    2013-01-01

    The capacity of HDL to induce cell cholesterol efflux is considered one of its main antiatherogenic properties. Little is known about the impact of such HDL function on vascular physiology. We investigated the relationship between ABCA1-dependent serum cholesterol efflux capacity (CEC), an HDL functionality indicator, and pulse wave velocity (PWV), an indicator of arterial stiffness. Serum of 167 healthy subjects was used to conduct CEC measurement, and carotid-femoral PWV was measured with a...

  14. PKC phosphorylates residues in the N-terminal of the DA transporter to regulate amphetamine-induced DA efflux.

    Science.gov (United States)

    Wang, Qiang; Bubula, Nancy; Brown, Jason; Wang, Yunliang; Kondev, Veronika; Vezina, Paul

    2016-05-27

    The DA transporter (DAT), a phosphoprotein, controls extracellular dopamine (DA) levels in the central nervous system through transport or reverse transport (efflux). Multiple lines of evidence support the claim that PKC significantly contributes to amphetamine-induced DA efflux. Other signaling pathways, involving CaMKII and ERK, have also been shown to regulate DAT mediated efflux. Here we assessed the contribution of putative PKC residues (S4, S7, S13) in the N-terminal of the DAT to amphetamine-induced DA efflux by transfecting DATs containing different serine to alanine (S-A) point mutations into DA pre-loaded HEK-293 cells and incubating these cells in amphetamine (2μM). The effects of a S-A mutation at the non-PKC residue S12 and a threonine to alanine (T-A) mutation at the ERK T53 residue were also assessed for comparison. WT-DATs were used as controls. In an initial experiment, we confirmed that inhibiting PKC with Go6976 (130nM) significantly reduced amphetamine-induced DA efflux. In subsequent experiments, cells transfected with the S4A, S12A, S13A, T53A and S4,7,13A mutants showed a reduction in amphetamine-induced DA efflux similar to that observed with Go6976. Interestingly, cells transfected with the S7A mutant, identified by some as a PKC-PKA residue, showed unperturbed WT-DAT levels of amphetamine-induced DA efflux. These results indicate that phosphorylation by PKC of select residues in the DAT N-terminal can regulate amphetamine-induced efflux. PKC can act either independently or in concert with other kinases such as ERK to produce this effect. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. Akt inhibition promotes ABCA1-mediated cholesterol efflux to ApoA-I through suppressing mTORC1.

    Directory of Open Access Journals (Sweden)

    Fumin Dong

    Full Text Available ATP-binding cassette transporter A1 (ABCA1 plays an essential role in mediating cholesterol efflux to apolipoprotein A-I (apoA-I, a major housekeeping mechanism for cellular cholesterol homeostasis. After initial engagement with ABCA1, apoA-I directly interacts with the plasma membrane to acquire cholesterol. This apoA-I lipidation process is also known to require cellular signaling processes, presumably to support cholesterol trafficking to the plasma membrane. We report here that one of major signaling pathways in mammalian cells, Akt, is also involved. In several cell models that express ABCA1 including macrophages, pancreatic beta cells and hepatocytes, inhibition of Akt increases cholesterol efflux to apoA-I. Importantly, Akt inhibition has little effect on cells expressing non-functional mutant of ABCA1, implicating a specific role of Akt in ABCA1 function. Furthermore, we provide evidence that mTORC1, a major downstream target of Akt, is also a negative regulator of cholesterol efflux. In cells where mTORC1 is constitutively activated due to tuberous sclerosis complex 2 deletion, cholesterol efflux to apoA-I is no longer sensitive to Akt activity. This suggests that Akt suppresses cholesterol efflux through mTORC1 activation. Indeed, inhibition of mTORC1 by rapamycin or Torin-1 promotes cholesterol efflux. On the other hand, autophagy, one of the major pathways of cholesterol trafficking, is increased upon Akt inhibition. Furthermore, Akt inhibition disrupts lipid rafts, which is known to promote cholesterol efflux to apoA-I. We therefore conclude that Akt, through its downstream targets, mTORC1 and hence autophagy, negatively regulates cholesterol efflux to apoA-I.

  16. Sodium content and sodium efflux of mononuclear leucocytes from young subjects at increased risk of developing essential hypertension

    DEFF Research Database (Denmark)

    Pedersen, K E; Nielsen, J R; Klitgaard, N A

    1990-01-01

    , and to analyze whether any such changes were associated with borderline hypertension and/or heredity. Four groups of subjects were evaluated: 28 normotensive (NTO) and 20 borderline hypertensive (BHO) offspring of hypertensives, 12 borderline hypertensives with normotensive parents (BH) and 28 normotensive...... subjects with normotensive parents (NT). The cellular sodium/potassium contents of the four groups were not discernibly different. Ouabain insensitive sodium efflux rate constant and corresponding absolute efflux were significantly increased in offspring of hypertensives. Ouabain sensitive absolute sodium...

  17. Functional characterization of Brucella melitensis NorMI, an efflux pump belonging to the multidrug and toxic compound extrusion family

    OpenAIRE

    Braibant, Martine; Zygmunt, Michel

    2002-01-01

    Two putative proteins (NorMI and NorMII) similar to the multidrug efflux protein NorM of Vibrio parahaemolyticus are encoded by the Brucella melitensis 16 M genome. We show that a drug-hypersusceptible Escherichia coli strain overexpressing NorMI displays increased resistance to norfloxacin, ciprofloxacin, gentamicin, tetraphenylphosphonium ion, acriflavine, and berberine. This elevated resistance was proven to be mediated by an energy-dependent efflux mechanism. NorMI belongs to the multidru...

  18. Bromide as a tracer for studying water movement and nitrate displacement in soils: comparison with stable isotope tracers; Bromid als Tracer zur Untersuchung der Wasserbewegung und der Nitratverlagerung in Boeden: Vergleich mit stabilisotopen Tracern

    Energy Technology Data Exchange (ETDEWEB)

    Russow, R.; Knappe, S. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Bad Lauchstaedt (Germany). Sektion Bodenforschung

    1999-02-01

    Tracers are an ideal means of studying water movement and associated nitrate displacement. Often bromide is preferred as a tracer because it is considered a representative tracer for water and because, being a conservative tracer (i.e. not involved in chemical and biological soil processes), it can be used for studying anion transport in soils. Moreover, it is less expensive and easier to measure than the stable isotopes deuterium and {sup 15}N. Its great advantage over radioactive tracers (e.g. tritium), which outweighs their extreme sensitivity and ease of measurement and which it has in common with stable isotopes, is that it does not require radiation protection measures. However, there are also constraints on the use of bromide as a tracer in soil/water/plant systems. Our own studies on different soils using D{sub 2}O, bromide and [{sup 15}N]-nitrate in lysimeters suggest that the above assumptions on bromide tracers need not always be valid under conditions as they prevail in biologically active soils. As the present paper shows, these studies permit a good assessment of the possibilities and limits to these tracers. [Deutsch] Fuer die Untersuchung der Wasserbewegung sowie der daran gekoppelten Nitrat-Verlagerung ist der Einsatz von Tracern das Mittel der Wahl. Dabei wird Bromid als Tracer haeufig bevorzugt, da es allgemein als ein repraesentativer Tracer fuer Wasser und als konservativer Tracer (nicht involviert in chemische und biologische Bodenprozesse) zur Untersuchung des Anionentransportes in Boeden angesehen wird und es gegenueber den stabilen Isotopen Deuterium und {sup 15}N billiger und einfacher zu bestimmen ist. Gegenueber den radioaktiven Tracern (z.B. Tritium), die zwar sehr empfindlich und einfach messbar sind, besteht der grosse Vorteil, dass, wie bei den stabilen Isotopen, keine Strahlenschutzmassnahmen ergriffen werden muessen. Es gibt jedoch auch einschraenkende Hinweise fuer die Verwendung von Bromid als Tracer im System Boden

  19. Modeling the dissociation conditions of salt hydrates and gas semiclathrate hydrates: application to lithium bromide, hydrogen iodide, and tetra-n-butylammonium bromide + carbon dioxide systems.

    Science.gov (United States)

    Paricaud, Patrice

    2011-01-20

    A thermodynamic approach is proposed to determine the dissociation conditions of salt hydrates and semiclathrate hydrates. The thermodynamic properties of the liquid phase are described with the SAFT-VRE equation of state, and the solid-liquid equilibria are solved by applying the Gibbs energy minimization criterion under stoichiometric constraints. The methodology is applied to water + halide salt systems, and an excellent description of the solid-liquid coexistence curves is obtained. The approach is extended to the water + tetra-n-butylammonium bromide (TBAB) binary mixture, and an accurate representation of the solid-liquid coexistence curves and dissociation enthalpies is obtained. The van der Waals-Platteeuw (vdW-P) theory combined with the new model for salt hydrates is used to determine the dissociation temperatures of semiclathrate hydrates of TBAB + carbon dioxide. A good description of the dissociation pressures of CO(2) semiclathrate hydrates is obtained over wide temperature, pressure, and TBAB composition ranges (AAD = 10.5%). For high TBAB weight fractions the new model predicts a change of hydrate structure from type A to type B as the partial pressure of CO(2) is increased. The model can also capture a change of behavior with respect to TBAB concentration, which has been observed experimentally: an increase of the TBAB weight fraction leads to a stabilization of the gas semiclathrate hydrate at low initial TBAB concentrations below the stoichiometric composition but leads to a destabilization of the hydrate at TBAB concentrations above the stoichiometric composition.

  20. Efflux pump inhibitors (EPIs as new antimicrobial agents against Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Momen Askoura

    2011-05-01

    Full Text Available Pseudomonas aeruginosa is an opportunistic human pathogen and one of the leading causes of nosocomial infections worldwide. The difficulty in treatment of pseudomonas infections arises from being multidrug resistant (MDR and exhibits resistance to most antimicrobial agents due to the expression of different mechanisms overcoming their effects. Of these resistance mechanisms, the active efflux pumps in Pseudomonas aeruginosa that belong to the resistance nodulation division (RND plays a very important role in extruding the antibiotics outside the bacterial cells providing a protective means against their antibacterial activity. Beside its role against the antimicrobial agents, these pumps can extrude biocides, detergents, and other metabolic inhibitors. It is clear that efflux pumps can be targets for new antimicrobial agents. Peptidomimetic compounds such as phenylalanine arginyl β-naphthylamide (PAβN have been introduced as efflux pump inhibitors (EPIs; their mechanism of action is through competitive inhibition with antibiotics on the efflux pump resulting in increased intracellular concentration of antibiotic, hence, restoring its antibacterial activity. The advantage of EPIs is the difficulty to develop bacterial resistance against them, but the disadvantage is their toxic property hindering their clinical application. The structure activity relationship of these compounds showed other derivatives from PAβN that are higher in their activity with higher solubility in biological fluids and decreased toxicity level. This raises further questions on how can we compact Pseudomonas infections. Of particular importance, the recent resurgence in the use of older antibiotics such as polymyxins and probably applying stricter control measures in order to prevent their spread in clinical sittings.

  1. Restoration of Chloride Efflux by Azithromycin in Airway Epithelial Cells of Cystic Fibrosis Patients▿

    Science.gov (United States)

    Saint-Criq, Vinciane; Rebeyrol, Carine; Ruffin, Manon; Roque, Telma; Guillot, Loïc; Jacquot, Jacky; Clement, Annick; Tabary, Olivier

    2011-01-01

    Azithromycin (AZM) has shown promising anti-inflammatory properties in chronic obstructive pulmonary diseases, and clinical studies have presented an improvement in the respiratory condition of cystic fibrosis (CF) patients. The aim of this study was to investigate, in human airway cells, the mechanism by which AZM has beneficial effects in CF. We demonstrated that AZM did not have any anti-inflammatory effect on CF airway cells but restored Cl− efflux. PMID:21220528

  2. Promising therapy of XDR-TB/MDR-TB with thioridazine an inhibitor of bacterial efflux pumps

    DEFF Research Database (Denmark)

    Amaral, L; Martins, M; Viveiros, M

    2008-01-01

    and which has been shown to inhibit efflux pumps of bacteria. The argument has been previously presented but no one seems to be listening - and the disease continues unabated when there is a very good probability that the suggested drug will prove to be effective. When the prognosis is poor, available...... therapy predictably ineffective and death is inevitable, compassionate therapy with TZ should be contemplated. The risks are small and the rewards great....

  3. Can celecoxib affect P-glycoprotein-mediated drug efflux? A microPET study

    Energy Technology Data Exchange (ETDEWEB)

    Vries, Erik F.J. de [Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB Groningen (Netherlands)], E-mail: e.f.j.de.vries@ngmb.umcg.nl; Doorduin, Janine; Vellinga, Namkje A.R.; Waarde, Aren van; Dierckx, Rudi A. [Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB Groningen (Netherlands); Klein, Hans C. [Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB Groningen (Netherlands); Department of Psychiatry, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB Groningen (Netherlands)

    2008-05-15

    Introduction: P-glycoprotein (Pgp) is an efflux pump that protects vital organs like the brain from toxic substances, but which is also associated with therapy resistance. The anti-inflammatory drug celecoxib potentiates the efficacy of several cytostatic and neurotropic drugs that are known Pgp substrates. To clarify whether Pgp is involved in the sensitizing effect of celecoxib, we investigated in vivo whether celecoxib is a substrate of Pgp and whether it can affect the efflux activity of the pump. Methods: In control rats and in rats treated with the Pgp modulator cyclosporin A (CsA), cerebral accumulation of radiolabeled [{sup 11}C]celecoxib was investigated by ex vivo biodistribution and micro-positron emission tomography imaging. In addition, the effect of unlabeled celecoxib and CsA (positive control) on the cerebral uptake of the Pgp substrate [{sup 11}C]verapamil was studied. Results: [{sup 11}C]Celecoxib uptake in rat brain was relatively high and homogeneously distributed. Treatment of rats with CsA only marginally increased cerebral tracer uptake, which is most likely due to reduced tracer clearance from plasma. [{sup 11}C]Verapamil brain uptake was more than 10-fold higher after treatment with CsA. In contrast, a high dose of celecoxib increased cerebral [{sup 11}C]verapamil uptake only twofold, which was accompanied by a similar increase in tracer concentration in plasma. Conclusions: This study shows that celecoxib is not a substrate of Pgp and does not substantially affect the Pgp-mediated efflux of [{sup 11}C]verapamil. Therefore, celecoxib-induced augmentation of the efficacy of chemotherapeutic and neurotropic drugs must be due to another mechanism than modulation of Pgp-mediated drug efflux.

  4. CFTR-dependent chloride efflux in cystic fibrosis mononuclear cells is increased by ivacaftor therapy.

    Science.gov (United States)

    Guerra, Lorenzo; D'Oria, Susanna; Favia, Maria; Castellani, Stefano; Santostasi, Teresa; Polizzi, Angela M; Mariggiò, Maria A; Gallo, Crescenzio; Casavola, Valeria; Montemurro, Pasqualina; Leonetti, Giuseppina; Manca, Antonio; Conese, Massimo

    2017-07-01

    The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) potentiator ivacaftor (Kalydeco®) improves clinical outcome in G551D cystic fibrosis (CF) patients. Here, we have investigated whether ivacaftor has a clinical impact on non-G551D gating mutations and function of circulating leukocytes as well. Seven patients were treated with ivacaftor and evaluated at baseline, and at 1-3 and 6 months. Besides clinical and systemic inflammatory parameters, circulating mononuclear cells (MNC) were evaluated for CFTR-dependent chloride efflux by spectrofluorimetry, neutrophils for oxidative burst by cytofluorimetry and HVCN1 mRNA expression by real time PCR. Ivacaftor determined a significant decrease in sweat chloride concentrations at all time points during treatment. Body mass index (BMI), FEV1 , and FVC showed an increasing trend. While C-reactive protein decreased significantly at 2 months, the opposite behavior was noticed for circulating monocytes. CFTR activity in MNC was found to increase significantly at 3 and 6 months. Neutrophil oxidative burst peaked at 2 months and then decreased to baseline. HVCN1 mRNA expression was significantly higher than baseline at 1-3 months and decreased after 6 months of treatment. The chloride efflux in MNC correlated positively with both FEV1 and FVC. On the other hand, sweat chloride correlated positively with CRP and WBC, and negatively with both respiratory function tests. A cluster analysis confirmed that sweat chloride, FEV1 , FVC, BMI, and MNC chloride efflux behaved as a single entity over time. In patients with non-G551D mutations, ivacaftor improved both chloride transport in sweat ducts and chloride efflux in MNC, that is, functions directly imputed to CFTR. © 2017 Wiley Periodicals, Inc.

  5. Transcriptomic and biochemical analyses identify a family of chlorhexidine efflux proteins

    Science.gov (United States)

    Hassan, Karl A.; Jackson, Scott M.; Penesyan, Anahit; Patching, Simon G.; Tetu, Sasha G.; Eijkelkamp, Bart A.; Brown, Melissa H.; Henderson, Peter J. F.; Paulsen, Ian. T.

    2013-01-01

    Chlorhexidine is widely used as an antiseptic or disinfectant in both hospital and community settings. A number of bacterial species display resistance to this membrane-active biocide. We examined the transcriptomic response of a representative nosocomial human pathogen, Acinetobacter baumannii, to chlorhexidine to identify the primary chlorhexidine resistance elements. The most highly up-regulated genes encoded components of a major multidrug efflux system, AdeAB. The next most highly overexpressed gene under chlorhexidine stress was annotated as encoding a hypothetical protein, named here as AceI. Orthologs of the aceI gene are conserved within the genomes of a broad range of proteobacterial species. Expression of aceI or its orthologs from several other γ- or β-proteobacterial species in Escherichia coli resulted in significant increases in resistance to chlorhexidine. Additionally, disruption of the aceI ortholog in Acinetobacter baylyi rendered it more susceptible to chlorhexidine. The AceI protein was localized to the membrane after overexpression in E. coli. This protein was purified, and binding assays demonstrated direct and specific interactions between AceI and chlorhexidine. Transport assays using [14C]-chlorhexidine determined that AceI was able to mediate the energy-dependent efflux of chlorhexidine. An E15Q AceI mutant with a mutation in a conserved acidic residue, although unable to mediate chlorhexidine resistance and transport, was still able to bind chlorhexidine. Taken together, these data are consistent with AceI being an active chlorhexidine efflux protein and the founding member of a family of bacterial drug efflux transporters. PMID:24277845

  6. Hydrologic profiling for greenhouse gas effluxes from natural grasslands in the prairie pothole region of Canada

    Science.gov (United States)

    Creed, Irena F.; Miller, Johnston; Aldred, David; Adams, Jennifer K.; Spitale, Salvatore; Bourbonniere, Rick A.

    2013-06-01

    prairie pothole physiographic region of North America is likely to be affected by climate change, and it is important to establish its baseline global warming potential as a basis for assessing global change effects. This study estimated the hydrologic effects on soil greenhouse gas efflux during the growing season along hydrologic profiles within natural prairie potholes ranging from the southern to northern limits of the prairie pothole region within central Canada. Soil moisture was found to be an important driver of differences in soil efflux along the hydrologic profiles and along the south-to-north gradient. The position of peak cumulative soil efflux varied along the hydrologic profile, with the N2O peak occurring at the backslope, the CO2 peaks at footslope and toeslope, and the CH4 peaks at toeslope and surface waters. When cumulative soil efflux was converted to global warming potential (Mg CO2 eq), the largest values were restricted to the narrow land-water interface in the south but expanded to a broader area of the hillslope in the north. CO2 was the major (> 95%) contributor to global warming potential. Omitting hydrologic controls on greenhouse gas fluxes from estimates of global warming potential led to substantial underestimates of the contributions of N2O and CH4. Arid regions in the south had smaller global warming potential than wetter regions in the north. If future climate projections for a warmer, drier climate in this region are realized, global warming potential from soil greenhouse gas fluxes will be smaller in this landscape, because the changing hydrologic conditions should result in a reduction of global warming potential from land surfaces, even as global warming potential from surface waters increases.

  7. Resveratrol counters systemic lupus erythematosus-associated atherogenicity by normalizing cholesterol efflux.

    Science.gov (United States)

    Voloshyna, Iryna; Teboul, Isaac; Littlefield, Michael J; Siegart, Nicolle M; Turi, George K; Fazzari, Melissa J; Carsons, Steven E; DeLeon, Joshua; Reiss, Allison B

    2016-08-01

    Resveratrol is a bioactive molecule used in dietary supplements and herbal medicines and consumed worldwide. Numerous investigations by our group and others have indicated cardioprotective and anti-inflammatory properties of resveratrol. The present study explored potential atheroprotective actions of resveratrol on cholesterol efflux in cultured human macrophages exposed to plasma from systemic lupus erythematosus (SLE) patients. These results were confirmed in ApoE(-/-)Fas(-/-) double knockout mice, displaying a lupus profile with accelerated atherosclerosis. Resveratrol treatment attenuated atherosclerosis in these mice. THP-1 human macrophages were exposed to 10% pooled or individual plasma from patients who met diagnostic criteria for SLE. Expression of multiple proteins involved in reverse cholesterol transport (ABCA1, ABCG1, SR-B1, and cytochrome P450 27-hydroxylase) was assessed using QRT-PCR and Western blotting techniques. Ten-week-old ApoE(-/-)Fas(-/-) double knockout mice (n = 30) were randomly divided into two equal groups of 15, one of which received 0.01% resveratrol for 10 consecutive weeks. Atherosclerosis progression was evaluated in murine aortas. Bone marrow-derived macrophages (BMDM) were cultured and expression of cholesterol efflux proteins was analyzed in each group of mice. Our data indicate that inhibition of cholesterol efflux by lupus plasma in THP-1 human macrophages is rescued by resveratrol. Similarly, administration of resveratrol in a lupus-like murine model reduces plaque formation in vivo and augments cholesterol efflux in BMDM. This study presents evidence for a beneficial role of resveratrol in atherosclerosis in the specific setting of SLE. Therefore, resveratrol may merit investigation as an additional resource available to reduce lipid deposition and atherosclerosis in humans, especially in such vulnerable populations as lupus patients. © 2016 by the Society for Experimental Biology and Medicine.

  8. Oxidation of micro or trace amounts of bromide to bromate by peroxodisulphate before their iodometric determination by titration or spectrophotometry.

    Science.gov (United States)

    Lundström, U

    1982-04-01

    The optimum conditions for the oxidation of bromide to bromate by peroxodisulphate at 120 degrees as well as for the decomposition of the excess of oxidant have been determined. The predicted advantages of this oxidizing agent, viz. minimal blanks and destruction of small amounts of interfering organic matter and reducing substances, were confirmed. The bromate was determined iodometrically either by titration with thiosulphate or by spectrophotometry in absence of oxygen at 355 nm. The titrimetric finish applied to 0.8-8 micromole of bromide gave a mean yield of 100.0%, s = 6 nmole. The spectrophotometric finish applied to 0.05-0.25 micromole of bromide gave a mean yield of 98.9%, s = 1.1 nmole. Interfering amounts of iodide present in the sample and oxidized to iodate can be corrected for by making use of the pH-dependence of the reaction of iodide with bromate and iodate.

  9. Combination of ozonation and photocatalysis for purification of aqueous effluents containing formic acid as probe pollutant and bromide ion.

    Science.gov (United States)

    Parrino, F; Camera-Roda, G; Loddo, V; Palmisano, G; Augugliaro, V

    2014-03-01

    The treatment by advanced oxidation processes (AOPs) of waters contaminated by organic pollutants and containing also innocuous bromide ions may generate bromate ions as a co-product. In the present work heterogeneous photocatalysis and ozonation have individually been applied and in combination (integrated process) to degrade the organic compounds in water containing also bromide anions. The results show that: i) the sole photocatalysis does not produce bromate ions and in the case of its presence, it is able to reduce bromate to innocuous bromide ions; ii) the integration of photocatalysis and ozonation synergistically enhances the oxidation capabilities; and iii) in the integrated process bromate ions are not produced as long as some oxidizable organics are present. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. The Research on Programmable Control System of Lithium-Bromide Absorption Refrigerating Air Conditioner Based on the Network

    Directory of Open Access Journals (Sweden)

    Sun Lunan

    2016-01-01

    Full Text Available This article regard the solar lithium-bromide absorption refrigerating air conditioning system as the research object, and it was conducting adequate research of the working principle of lithium bromide absorption refrigerating machine, also it was analyzing the requirements of control system about solar energy air conditioning. Then the solar energy air conditioning control system was designed based on PLC, this system was given priority to field bus control system, and the remote monitoring is complementary, which was combining the network remote monitoring technology. So that it realized the automatic control and intelligent control of new lithium bromide absorption refrigerating air conditioning system with solar energy, also, it ensured the control system can automatically detect and adjust when the external conditions was random changing, to make air conditioning work effectively and steadily, ultimately ,it has great research significance to research the air conditioning control system with solar energy.

  11. Possible involvement of hyphal phosphatase in phosphate efflux from intraradical hyphae isolated from mycorrhizal roots colonized by Gigaspora margarita.

    Science.gov (United States)

    Kojima, Tomoko; Saito, Masanori

    2004-06-01

    We developed a method for separating physiologically active intraradical hyphae of arbuscular mycorrhizal (AM) fungi from mycorrhizal roots, allowing the hyphae to be used for physiological and biochemical experiments. In the present study, the phosphate efflux from the intraradical hyphae in vitro was examined in relation to hyphal phosphatase activity. Onion seedlings (Allium cepa) were planted in the soil inoculated with Gigaspora margarita. Six weeks after transplanting, the intraradical hyphae were isolated from the mycorrhizal roots using plant cell-wall digestion enzymes. The hyphae were incubated briefly at 25 degrees C in a buffer solution (50 mM Tris/HCl, pH 7.4), then incubated for 2 h and gently shaken with various inhibitors. Phosphate efflux, the amount of phosphate released to the buffer, was analysed by EnzChek phosphate assay kit. Hyphal phosphatase activity was stained histochemically and the proportion of phosphatase-active arbuscules was examined for each inhibitor. Phosphate effluxes were to some degree reduced by all inhibitors used, while the phosphatase inhibitor, BeSO4, greatly reduced the efflux. The degree of inhibition in the arbuscular phosphatase by each chemical was closely correlated to the decrease in the phosphate efflux. These results suggest that hyphal phosphatase may be partially involved in the phosphate efflux process from intraradical hyphae.

  12. ESTIMATE OF CO2 EFFLUX OF SOIL, OF A TRANSITION FOREST IN NORTHWEST OF MATO GROSSO STATE, USING MULTIPLE REGRESSION

    Directory of Open Access Journals (Sweden)

    Carla Maria Abido Valentini

    2008-03-01

    Full Text Available Many research groups have being studying the contribution of tropical forests to the global carbon cycle, and theclimatic consequences of substituting the forests for pastures. Considering that soil CO2 efflux is the greater component of the carboncycle of the biosphere, this work found an equation for estimating the soil CO2 efflux of an area of the Transition Forest, using a modelof multiple regression for time series data of temperature and soil moisture. The study was carried out in the northwest of MatoGrosso, Brazil (11°24.75’S; 55°19.50’W, in a transition forest between cerrado and AmazonForest, 50 km far from Sinop county.Each month, throughout one year, it was measured soil CO2 efflux, temperature and soil moisture. The annual average of soil CO2 efflux was 7.5 ± 0.6 (mean ± SE ì mol m-2 s-1, the annual mean soil temperature was 25,06 ± 0.12 (mean ± SE ºC. The study indicatedthat the humidity had high influence on soil CO2 efflux; however the results were more significant using a multiple regression modelthat estimated the logarithm of soil CO2 efflux, considering time, soil moisture and the interaction between time duration and theinverse of soil temperature. .

  13. Efflux of Creatine Kinase from Isolated Soleus Muscle Depends on Age, Sex and Type of Exercise in Mice

    Directory of Open Access Journals (Sweden)

    Juozas Baltusnikas, Tomas Venckunas, Audrius Kilikevicius, Andrej Fokin, Aivaras Ratkevicius

    2015-06-01

    Full Text Available Elevated plasma creatine kinase (CK activity is often used as an indicator of exercise-induced muscle damage. Our aim was to study effects of contraction type, sex and age on CK efflux from isolated skeletal muscles of mice. The soleus muscle (SOL of adult (7.5-month old female C57BL/6J mice was subjected to either 100 passive stretches, isometric contractions or eccentric contractions, and muscle CK efflux was assessed after two-hour incubation in vitro. SOL of young (3-month old male and female mice was studied after 100 eccentric contractions. For adult females, muscle CK efflux was larger (p < 0.05 after eccentric contractions than after incubation without exercise (698 ± 344 vs. 268 ± 184 mU·h−1, respectively, but smaller (p < 0.05 than for young females after the same type of exercise (1069 ± 341 mU·h−1. Eccentric exercise-induced CK efflux was larger in muscles of young males compared to young females (2046 ± 317 vs 1069 ± 341 mU · h−1, respectively, p < 0.001. Our results show that eccentric contractions induce a significant increase in muscle CK efflux immediately after exercise. Isolated muscle resistance to exercise-induced CK efflux depends on age and sex of mice.

  14. Is the decreased high-density lipoprotein cholesterol in the metabolic syndrome due to cellular lipid efflux defect?

    Science.gov (United States)

    Alenezi, Mohammad Y; Marcil, Michel; Blank, David; Sherman, Mark; Genest, Jacques

    2004-02-01

    The metabolic syndrome (MS) is associated with cardiovascular disease. The low high-density lipoprotein cholesterol (HDL-C) seen in the MS is associated with increased hepatic secretion of apolipoprotein B-containing lipoproteins. Patients with low HDL-C and abnormal cellular lipid efflux due to ABCA1 gene defects (Tangier disease) also have elevated plasma triglycerides. In the present study, we examined the cellular cholesterol and phospholipid efflux in patients with low HDL-C and features of the MS. Forty-four patients with a HDL-C below the fifth percentile for age and gender were selected. The MS was defined by a low HDL-C and at least two additional features: body mass index at least 30 kg/m(2), plasma triglycerides at least 150 mg/dl, fasting glucose at least 110 mg/dl, and blood pressure at least 130/85 mm Hg. Cellular lipid efflux was examined on fibroblasts obtained from study subjects, nine normal controls and six subjects with Tangier disease. In 22 patients identified with the MS, HDL-C was 21 +/- 7 mg/dl, triglyceride levels were 340 +/- 157 mg/dl, and cellular cholesterol and phospholipid efflux were 107 +/- 18% and 105 +/- 17% of controls, respectively. No patient with the MS and low HDL-C showed a cellular lipid efflux defect. We conclude that primary cellular lipid efflux defects do not contribute to the low HDL-C frequently encountered in the MS.

  15. [Effects of plastic film mulching on soil CO2 efflux and CO2 concentration in an oasis cotton field].

    Science.gov (United States)

    Yu, Yong-xiang; Zhao, Cheng-yi; Jia, Hong-tao; Yu, Bo; Zhou, Tian-he; Yang, Yu-guang; Zhao, Hua

    2015-01-01

    A field study was conducted to compare soil CO2 efflux and CO2 concentration between mulched and non-mulched cotton fields by using closed chamber method and diffusion chamber technique. Soil CO2 efflux and CO2 concentration exhibited a similar seasonal pattern, decreasing from July to October. Mulched field had a lower soil CO2 efflux but a higher CO2 concentration, compared to those of non-mulched fields. Over the measurement period, cumulative CO2 efflux was 1871.95 kg C . hm-2 for mulched field and 2032.81 kg C . hm-2 for non-mulched field. Soil CO2 concentration was higher in mulched field (ranging from 5137 to 25945 µL . L-1) than in non- mulched field (ranging from 2165 to 23986 µL . L-1). The correlation coefficients between soil CO2 concentrations at different depths and soil CO2 effluxes were 0.60 to 0.73 and 0.57 to 0.75 for the mulched and non-mulched fields, indicating that soil CO2 concentration played a crucial role in soil CO2 emission. The Q10 values were 2.77 and 2.48 for the mulched and non-mulched fields, respectively, suggesting that CO2 efflux in mulched field was more sensitive to the temperature.

  16. Soil CO2 Efflux Dynamics in the Northern Pantanal of Mato Grosso, Brazil during the Wet-Dry Season Transition

    Science.gov (United States)

    Pinto-Jr, O. B.; Vourlitis, G. L.; Hentz, C. S.; Arruda, P. H. Z. D.; Santanna, F. B.; Dias, M. D. F.; de Musis, C. R.; Nogueira, J. D. S.

    2014-12-01

    The roles of tropical wetlands in the global carbon (C) cycle are still poorly understood, especially in seasonally flooded forests that are expected to be important sinks for atmospheric CO2. We measured soil CO2 efflux during the wet-dry transition period in a seasonally flooded palm-dominated forest (locally known as Acorizal) to determine the effect of litter input and seasonal hydrology. Measurements were performed monthly as part of a field litter manipulation experiment consisting of three treatments (litter removal, litter addition, and control; n = 6 plots per treatment), and our research objectives were to determine how soil CO2 efflux varied as a function of (1) litter input, (2) root density, and (3) seasonal variation in soil water content. We found that litter addition significantly increased soil CO2 efflux, but there was no relationship between root density and soil CO2 efflux. Efflux was highest during the wet season and declined as soil water content declined. Our data demonstrate that variations in litter inputs and soil water content are important controls on soil CO2 efflux in seasonally flooded tropical forests.

  17. Escherichia coli tetracycline efflux determinants in relation to tetracycline residues in chicken.

    Science.gov (United States)

    S N, Al-Bahry; B M, Al-Mashani; A S, Al-Ansari; A E, Elshafie; I Y, Mahmoud

    2013-09-01

    To screen for Escherichia coli (E. coli) resistant to tetracycline, followed by identification of tet efflux genes by polymerase chain reaction (PCR). In addition, detection of tetracycline residues in chicken livers and kidneys were conducted using high performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS). Strains of E. coli were isolated from samples of chicken colon and screened for tetracycline resistance. Tetracycline genes conferring resistance (Tc(r)) were detected by polymerase chain reaction (PCR). Most of the isolates were resistant to tetracycline (97.9%). PCR analysis indicated that Tc(r)E. coli R-plasmids contained tet(A), tet(B) and a combination of both efflux genes. None of the isolates contained other efflux tet genes tet (C, D, E and Y). High performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS), a sensitive technique, was used to detect residues of chlortetracycline (CTC), oxytetracycline (OTC), doxycycline (DC) in chicken livers and kidneys. The samples containing tetracycline residues were at 0.13-0.65 pg/μL levels. Tetracycline and other antibiotics are commonly used in the poultry and meat production industry for prevention of microbial infections. Multiple antibiotic resistant bacteria in Oman have increased to alarming levels, threatening public health, domestic and may have adverse effect on environment. Copyright © 2013 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  18. ABCA1-dependent serum cholesterol efflux capacity inversely correlates with pulse wave velocity in healthy subjects.

    Science.gov (United States)

    Favari, Elda; Ronda, Nicoletta; Adorni, Maria Pia; Zimetti, Francesca; Salvi, Paolo; Manfredini, Matteo; Bernini, Franco; Borghi, Claudio; Cicero, Arrigo F G

    2013-01-01

    The capacity of HDL to induce cell cholesterol efflux is considered one of its main antiatherogenic properties. Little is known about the impact of such HDL function on vascular physiology. We investigated the relationship between ABCA1-dependent serum cholesterol efflux capacity (CEC), an HDL functionality indicator, and pulse wave velocity (PWV), an indicator of arterial stiffness. Serum of 167 healthy subjects was used to conduct CEC measurement, and carotid-femoral PWV was measured with a high-fidelity tonometer. J774 macrophages, labeled with [(3)H]cholesterol and stimulated to express ABCA1, were exposed to sera; the difference between cholesterol efflux from stimulated and unstimulated cells provided specific ABCA1-mediated CEC. PWV is inversely correlated with ABCA1-dependent CEC (r = -0.183; P = 0.018). Moreover, controlling for age, sex, body mass index, mean arterial pressure, serum LDL, HDL-cholesterol, and fasting plasma glucose, PWV displays a significant negative regression on ABCA1-dependent CEC (β = -0.204; 95% confidence interval, -0.371 to -0.037). The finding that ABCA1-dependent CEC, but not serum HDL cholesterol level (r = -0.002; P = 0.985), is a significant predictor of PWV in healthy subjects points to the relevance of HDL function in vascular physiology and arterial stiffness prevention.

  19. The implication of cigarette smoking and cessation on macrophage cholesterol efflux in coronary artery disease patients.

    Science.gov (United States)

    Song, Wei; Wang, Wei; Dou, Li-Yang; Wang, Yu; Xu, Yan; Chen, Lian-Feng; Yan, Xiao-Wei

    2015-03-01

    We investigated ATP-binding cassette transporters A1/G1 expression and function in mediating cholesterol efflux by examining the macrophages of cigarette-smoking patients with coronary artery disease (CAD) before and after smoking abstinence. Peripheral blood monocyte cells were collected from nonsmokers (n = 17), non-CAD (NCAD) smokers (n = 35), and CAD smokers (n = 32) before and after 3 months of smoking cessation. We found that the ABCA1 expression level was lower in macrophages from NCAD and CAD smokers than from nonsmokers at baseline. The ABCA1 function of mediating cholesterol efflux was reduced in NCAD and CAD smokers as compared with nonsmokers. After 3 months of smoking cessation, ABCA1 expression and function were improved in CAD smokers. However, ABCG1 expression and function did not change after smoking cessation. Furthermore, ABCA1 expression was inhibited by tar in human acute monocytic leukemia cell line THP-1-derived macrophages through the inhibition of liver X receptors. Nicotine and carbon monoxide did not inhibit ABCA1 expression. Our results indicate that chronic cigarette smoking impaired ABCA1-mediated cholesterol efflux in macrophages and that tobacco abstinence reversed the function and expression of ABCA1, especially in CAD patients. It was tobacco tar, rather than nicotine or carbon monoxide, that played a major role in the tobacco-induced disturbance of cellular cholesterol homeostasis. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

  20. Two Coregulated Efflux Transporters Modulate Intracellular Heme and Protoporphyrin IX Availability in Streptococcus agalactiae

    Science.gov (United States)

    Fernandez, Annabelle; Lechardeur, Delphine; Derré-Bobillot, Aurélie; Couvé, Elisabeth; Gaudu, Philippe; Gruss, Alexandra

    2010-01-01

    Streptococcus agalactiae is a major neonatal pathogen whose infectious route involves septicemia. This pathogen does not synthesize heme, but scavenges it from blood to activate a respiration metabolism, which increases bacterial cell density and is required for full virulence. Factors that regulate heme pools in S. agalactiae are unknown. Here we report that one main strategy of heme and protoporphyrin IX (PPIX) homeostasis in S. agalactiae is based on a regulated system of efflux using two newly characterized operons, gbs1753 gbs1752 (called pefA pefB), and gbs1402 gbs1401 gbs1400 (called pefR pefC pefD), where pef stands for ‘porphyrin-regulated efflux’. In vitro and in vivo data show that PefR, a MarR-superfamily protein, is a repressor of both operons. Heme or PPIX both alleviate PefR-mediated repression. We show that bacteria inactivated for both Pef efflux systems display accrued sensitivity to these porphyrins, and give evidence that they accumulate intracellularly. The ΔpefR mutant, in which both pef operons are up-regulated, is defective for heme-dependent respiration, and attenuated for virulence. We conclude that this new efflux regulon controls intracellular heme and PPIX availability in S. agalactiae, and is needed for its capacity to undergo respiration metabolism, and to infect the host. PMID:20421944

  1. Expression of ABC Efflux transporters in placenta from women with insulin-managed diabetes.

    Science.gov (United States)

    Anger, Gregory J; Cressman, Alex M; Piquette-Miller, Micheline

    2012-01-01

    Drug efflux transporters in the placenta can significantly influence the materno-fetal transfer of a diverse array of drugs and other xenobiotics. To determine if clinically important drug efflux transporter expression is altered in pregnancies complicated by gestational diabetes mellitus (GDM-I) or type 1 diabetes mellitus (T1DM-I), we compared the expression of multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 2 (MRP2) and the breast cancer resistance protein (BCRP) via western blotting and quantitative real-time polymerase chain reaction in samples obtained from insulin-managed diabetic pregnancies to healthy term-matched controls. At the level of mRNA, we found significantly increased expression of MDR1 in the GDM-I group compared to both the T1DM-I (pchanges in the placental protein expression of MDR1, MRP2, and BCRP were not detected (p>0.05). Interestingly, there was a significant, positive correlation observed between plasma hemoglobin A1c levels (a retrospective marker of glycemic control) and both BCRP protein expression (r = 0.45, pmanaged DM groups. Collectively, the data suggest that the expression of placental efflux transporters is not altered in pregnancies complicated by diabetes when hyperglycemia is managed; however, given the relationship between BCRP expression and plasma hemoglobin A1c levels it is plausible that their expression could change in poorly managed diabetes.

  2. The metal efflux island of Legionella pneumophila is not required for survival in macrophages and amoebas.

    Science.gov (United States)

    Kim, Eun-Hae; Charpentier, Xavier; Torres-Urquidy, Oscar; McEvoy, Megan M; Rensing, Christopher

    2009-12-01

    Legionella pneumophila is an intracellular pathogen causing pneumonia-like disease in humans. A 43-kb putative heavy metal efflux gene island was found on the L. pneumophila genome. Large Legionella deletion strains of the metal efflux genes were tested in human THP-1-derived macrophages and amoebal Acanthamoeba castellanii cells and were able to survive and replicate similar to the wild type, suggesting that they do not play a significant role within the intracellular environment. Examination of the sequence of this genomic island revealed that some genes were not accurately annotated and there were no known metal-responsive regulators encoded in this region. Therefore, functional roles of these metal resistance genes were tested by conducting metal resistance assays. Individual genes were cloned in an expression vector and expressed in an appropriate metal-sensitive Escherichia coli background with varying concentrations of the tested metal. Of the 11 efflux systems, a role was determined only for one. A Cu(I)-translocating P(IB)-type ATPase was shown to be encoded by lpg1024. This gene, termed copA, complemented a copper-sensitive (Delta copA) E. coli strain in trans and was able to confer copper resistance.

  3. Dopamine efflux in response to ultraviolet radiation in addicted sunbed users.

    Science.gov (United States)

    Aubert, Pamela M; Seibyl, John P; Price, Julianne L; Harris, Thomas S; Filbey, Francesca M; Jacobe, Heidi; Devous, Michael D; Adinoff, Bryon

    2016-05-30

    Compulsive tanning despite awareness of ultraviolet radiation (UVR) carcinogenicity may represent an "addictive" behavior. Many addictive disorders are associated with alterations in dopamine (D2/D3) receptor binding and dopamine reactivity in the brain's reward pathway. To determine if compulsive tanners exhibited neurobiologic responses similar to other addictive disorders, this study assessed basal striatal D2/D3 binding and UVR-induced striatal dopamine efflux in ten addicted and ten infrequent tanners. In a double-blind crossover trial, UVR or sham UVR was administered in separate sessions during brain imaging with single photon emission computerized tomography (SPECT). Basal D2/D3 receptor density and UVR-induced dopamine efflux in the caudate were assessed using (123)I-iodobenzamide ((123)I-IBZM) binding potential non-displaceable (BPnd). Basal BPnd did not significantly differ between addicted and infrequent tanners. Whereas neither UVR nor sham UVR induced significant changes in bilateral caudate BPnd in either group, post-hoc analyses revealed left caudate BPnd significantly decreased (reflecting increased dopamine efflux) in the addicted tanners - but not the infrequent tanners - during the UVR session only. Bilateral ∆BPnd correlated with tanning severity only in the addicted tanners. These preliminary findings are consistent with a stronger neural rewarding response to UVR in addicted tanners, supporting a cutaneous-neural connection driving excessive sunbed use. Copyright © 2016. Published by Elsevier Ireland Ltd.

  4. Efflux-mediated resistance to a benzothiadiazol derivative effective against Burkholderia cenocepacia

    Directory of Open Access Journals (Sweden)

    Viola Camilla eScoffone

    2015-08-01

    Full Text Available Burkholderia cenocepacia is a major concern for people suffering from Cystic Fibrosis as it contributes to serious respiratory tract infections. The lack of drugs effective against this opportunistic pathogen, along with the high level of resistance to multiple antibiotics, render the treatment of these infections particularly difficult.Here a new compound, belonging to the 2,1,3-benzothiadiazol-5-yl family (10126109, with a bactericidal effect and a MIC of 8 µg/ml against B. cenocepacia, is described. The compound is not cytotoxic and effective against B. cenocepacia clinical isolates and members of all the known Burkholderia cepacia complex species.Spontaneous mutants resistant to 10126109 were isolated and mutations in the MerR transcriptional regulator BCAM1948 were identified. In this way, a mechanism of resistance to this new molecule was described, which relies on the overexpression of the RND-9 efflux pump. Indeed, rnd-9 overexpression was confirmed by qRT-PCR, and RND-9 was identified in the membrane fractions of the mutant strains. Moreover, the increase in the MIC values of different drugs in the mutant strains, together with complementation experiments, suggested the involvement of RND-9 in the efflux of 10126109, thus indicating again the central role of efflux transporters in B. cenocepacia drug resistance.

  5. Characterization of the corrosion products formed on mild steel in acidic medium with N-octadecylpyridinium bromide as corrosion inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Nava, N., E-mail: tnava@imp.mx; Likhanova, N. V. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Olivares-Xometl, O. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria Quimica (Mexico); Flores, E. A. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Lijanova, I. V. [CIITEC, Instituto Politecnico Nacional (Mexico)

    2011-11-15

    The characterization of the corrosion products formed on mild steel SAE 1018 after 2 months exposure in aqueous sulfuric acid with and without corrosion inhibitor N-octadecylpyridinium bromide has been carried out by means of transmission {sup 57}Fe Moessbauer spectroscopy and X-ray powder diffraction (XRD). The major constituent of the rust formed in this environment without corrosion inhibitor is goethite ({alpha}-FeOOH). The samples with N-octadecylpyridinium bromide contain rozenite and large amounts of melanterite in the corrosion layers.

  6. tBuLi-Mediated One-Pot Direct Highly Selective Cross-Coupling of Two Distinct Aryl Bromides.

    Science.gov (United States)

    Vila, Carlos; Cembellín, Sara; Hornillos, Valentín; Giannerini, Massimo; Fañanás-Mastral, Martín; Feringa, Ben L

    2015-10-26

    A Pd-catalyzed direct cross-coupling of two distinct aryl bromides mediated by tBuLi is described. The use of [Pd-PEPPSI-IPr] or [Pd-PEPPSI-IPent] as catalyst allows for the efficient one-pot synthesis of unsymmetrical biaryls at room temperature. The key for this selective cross-coupling is the use of an ortho-substituted bromide that undergoes lithium-halogen exchange preferentially. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Characterization of the corrosion products formed on mild steel in acidic medium with N-octadecylpyridinium bromide as corrosion inhibitor

    Science.gov (United States)

    Nava, N.; Likhanova, N. V.; Olivares-Xometl, O.; Flores, E. A.; Lijanova, I. V.

    2011-11-01

    The characterization of the corrosion products formed on mild steel SAE 1018 after 2 months exposure in aqueous sulfuric acid with and without corrosion inhibitor N-octadecylpyridinium bromide has been carried out by means of transmission 57Fe Mössbauer spectroscopy and X-ray powder diffraction (XRD). The major constituent of the rust formed in this environment without corrosion inhibitor is goethite ( α-FeOOH). The samples with N-octadecylpyridinium bromide contain rozenite and large amounts of melanterite in the corrosion layers.

  8. Pyridostigmine bromide versus fludrocortisone in the treatment of orthostatic hypotension in Parkinson's disease - a randomized controlled trial.

    Science.gov (United States)

    Schreglmann, S R; Büchele, F; Sommerauer, M; Epprecht, L; Kägi, G; Hägele-Link, S; Götze, O; Zimmerli, L; Waldvogel, D; Baumann, C R

    2017-04-01

    Evidence for effective treatment options for orthostatic hypotension (OH) in Parkinson's disease (PD) is scarce. Elevation of cholinergic tone with pyridostigmine bromide has been reported as a way to improve blood pressure (bp) regulation in neurogenic hypotension without causing supine hypertension. This was a double-centre, double-blind, randomized, active-control, crossover, phase II non-inferiority trial of pyridostigmine bromide for OH in PD (clinicaltrials.gov NCT01993680). Patients with confirmed OH were randomized to 14 days 3 × 60 mg/day pyridostigmine bromide or 1 × 0.2 mg/day fludrocortisone before crossover. Outcome was measured by peripheral and central bp monitoring during the Schellong manoeuvre and questionnaires. Thirteen participants were enrolled between April 2013 and April 2015 with nine participants completing each trial arm. Repeated measures comparison showed a significant 37% improvement with fludrocortisone for the primary outcome diastolic bp drop on orthostatic challenge (baseline 22.9 ± 13.6 vs. pyridostigmine bromide 22.1 ± 17.0 vs. fludrocortisone 14.0 ± 12.6 mmHg; P = 0.04), whilst pyridostigmine bromide had no effect. Fludrocortisone caused an 11% peripheral systolic supine bp rise (baseline 128.4 ± 12.8 vs. pyridostigmine bromide 130.4 ± 18.3 vs. fludrocortisone 143.2 ± 10.1 mmHg; P = 0.01) but no central mean arterial supine bp rise (baseline 107.2 ± 7.8 vs. pyridostigmine bromide 97.0 ± 12.0 vs. fludrocortisone 107.3 ± 6.3 mmHg; P = 0.047). Subjective OH severity, motor score and quality of life remained unchanged by both study interventions. Pyridostigmine bromide is inferior to fludrocortisone in the treatment of OH in PD. This trial provides first objective evidence of the efficacy of 0.2 mg/day fludrocortisone for OH in PD, causing minor peripheral but no central supine hypertension. In addition to peripheral bp, future trials should include central bp measurements, known to correlate more closely with

  9. Transfer of biosynthesized gold nanoparticles from water into an ionic liquid using alkyltrimethyl ammonium bromide: an anion-exchange process.

    Science.gov (United States)

    Zhou, Yao; Lin, Wenshuang; Wang, Huixuan; Li, Qingbiao; Huang, Jiale; Du, Mingming; Lin, Liqin; Gao, Yixian; Lin, Ling; He, Ning

    2011-01-04

    Biosynthesized gold nanoparticles (GNPs) were transferred from water to a hydrophobic ionic liquid (IL), [Bmim]PF(6), with the assistance of alkyl trimethyl ammonium bromide. The phase transfer mechanism was illustrated through the exemplification of cetyltrimethyl ammonium bromide (CTAB). Interaction between GNPs and CTAB was demonstrated through zeta potential analysis. Moreover, an anion-exchange process was discovered between CTAB and IL. During the process, the hydrophobic CTAPF(6) formed in situ on the GNPs led to the hydrophobization and thus phase transfer of the GNPs. The phase transfer efficiency was found to be size-dependent.

  10. Multiple alternative substrate kinetics.

    Science.gov (United States)

    Anderson, Vernon E

    2015-11-01

    The specificity of enzymes for their respective substrates has been a focal point of enzyme kinetics since the initial characterization of metabolic chemistry. Various processes to quantify an enzyme's specificity using kinetics have been utilized over the decades. Fersht's definition of the ratio kcat/Km for two different substrates as the "specificity constant" (ref [7]), based on the premise that the important specificity existed when the substrates were competing in the same reaction, has become a consensus standard for enzymes obeying Michaelis-Menten kinetics. The expansion of the theory for the determination of the relative specificity constants for a very large number of competing substrates, e.g. those present in a combinatorial library, in a single reaction mixture has been developed in this contribution. The ratio of kcat/Km for isotopologs has also become a standard in mechanistic enzymology where kinetic isotope effects have been measured by the development of internal competition experiments with extreme precision. This contribution extends the theory of kinetic isotope effects to internal competition between three isotopologs present at non-tracer concentrations in the same reaction mix. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment. Published by Elsevier B.V.

  11. Responses of soil CO2 efflux to changes in plant CO2 uptake and transpiration

    Science.gov (United States)

    Balogh, János; de Luca, Giulia; Mészáros, Ádám; Trieber, Júlia; Gecse, Bernadett; Fóti, Szilvia; Pintér, Krisztina; Nagy, Zoltán

    2017-04-01

    Biotic drivers of soil respiration represent a significant supply-side (plant) control of the process. Those biotic drivers that integrate over longer time periods are useful in describing the phenological changes and physiological state of the vegetation, but they are not suitable to explain the diel variability of soil respiration. Two plant physiological processes, acting in opposite directions, could be relevant at diel timescale: (1) photosynthesis, and (2) transpiration. Firstly, it was recently found that photosynthesis has a time-lagged (a few hours) positive effect on the respiration of roots and root-associated microbes. This can be explainedby an increase in easily accessible non-structural hydrocarbon sources for the roots and root-associated organisms within this period. Secondly, it was found that the effect of transpiration could reduce root respiration due to CO2 transport through the transpiration stream, and this effect is expected to be immediate. Removing the effect of the abiotic drivers from the soil efflux signal could help to clarify the role of other driving variables. In the present study, we conducted manipulation measurements in lab environment to be able to detect the effects of the plant physiological variables (CO2 uptake, transpiration) on soil CO2 efflux. Plant individuals were planted into field soil samples in small pots. Transpiration manipulation was done by regulating vapour pressure of the air around the plant canopy and by inhibitors. Photosynthesis manipulation consisted of programmed absence of light. Isotopic signatures of soil respiration were used for estimating the contribution of the autotrophic and heterotrophic soil respiration components. 13CO2 concentration of the CO2 efflux of the different soil components was measured continuously in open system by cavity ring-down spectroscopy (Picarro G1101-i gas analyser). Keeling-plot approach was also used to calculate the isotopic signals of the sources. According to the

  12. Structure-function relationships in reconstituted HDL: Focus on antioxidative activity and cholesterol efflux capacity.

    Science.gov (United States)

    Cukier, Alexandre M O; Therond, Patrice; Didichenko, Svetlana A; Guillas, Isabelle; Chapman, M John; Wright, Samuel D; Kontush, Anatol

    2017-09-01

    High-density lipoprotein (HDL) contains multiple components that endow it with biological activities. Apolipoprotein A-I (apoA-I) and surface phospholipids contribute to these activities; however, structure-function relationships in HDL particles remain incompletely characterised. Reconstituted HDLs (rHDLs) were prepared from apoA-I and soy phosphatidylcholine (PC) at molar ratios of 1:50, 1:100 and 1:150. Oxidative status of apoA-I was varied using controlled oxidation of Met112 residue. HDL-mediated inactivation of PC hydroperoxides (PCOOH) derived from mildly pre-oxidized low-density lipoprotein (LDL) was evaluated by HPLC with chemiluminescent detection in HDL+LDL mixtures and re-isolated LDL. Cellular cholesterol efflux was characterised in RAW264.7 macrophages. rHDL inactivated LDL-derived PCOOH in a dose- and time-dependent manner. The capacity of rHDL to both inactivate PCOOH and efflux cholesterol via ATP-binding cassette transporter A1 (ABCA1) increased with increasing apoA-I/PC ratio proportionally to the apoA-I content in rHDL. Controlled oxidation of apoA-I Met112 gradually decreased PCOOH-inactivating capacity of rHDL but increased ABCA1-mediated cellular cholesterol efflux. Increasing apoA-I content in rHDL enhanced its antioxidative activity towards oxidized LDL and cholesterol efflux capacity via ABCA1, whereas oxidation of apoA-I Met112 decreased the antioxidative activity but increased the cholesterol efflux. These findings provide important considerations in the design of future HDL therapeutics. Non-standard abbreviations and acronyms: AAPH, 2,2'-azobis(-amidinopropane) dihydrochloride; ABCA1, ATP-binding cassette transporter A1; apoA-I, apolipoprotein A-I; BHT, butylated hydroxytoluene; CV, cardiovascular; EDTA, ethylenediaminetetraacetic acid; HDL-C, high-density lipoprotein cholesterol; LOOH, lipid hydroperoxides; Met(O), methionine sulfoxide; Met112, methionine 112 residue; Met86, methionine 86 residue; oxLDL, oxidized low

  13. Copper uptake kinetics and regulation in a marine fish after waterborne copper acclimation

    Energy Technology Data Exchange (ETDEWEB)

    Dang Fei; Zhong Huan [AMCE and Department of Biology, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong); Wang Wenxiong, E-mail: wwang@ust.hk [AMCE and Department of Biology, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong)

    2009-09-14

    The uptake kinetics and regulation of copper in a marine predatory fish, the black sea bream Acanthopagrus schlegeli after acclimation to waterborne Cu were examined, using radiotracer techniques. The dissolved Cu uptake followed a linear pattern during the time of exposure, and the calculated uptake rate constant was 6.24 L kg{sup -1} day{sup -1}. The efflux rate constant was 0.091 day{sup -1} following dietary uptake of Cu, and the dietary assimilation efficiency (AE) of Cu varied between 1.7% and 10.9% after the fish were fed with three types of prey (oysters, clams and brine shrimp). After the fish were acclimated at a nominal concentration of 50 {mu}g Cu L{sup -1} for 14 days, the Cu uptake rate and efflux rate constant did not change significantly, but the Cu body concentrations and metallothionein (MT) concentrations in fish tissues increased significantly. Subcellular Cu distributions were also modified. Significant MT induction was observed in response to increased Cu tissue concentrations, indicating that MT rather than the uptake kinetics may play a primary role in Cu regulation during waterborne Cu acclimation in this marine fish. Moreover, the high Cu efflux may also be important in Cu regulation during long-term exposure. Our modeling calculations indicated that dietary uptake was likely to be the main route for Cu bioaccumulation in the fish, and the relative contribution of waterborne and dietary uptake depended on the bioconcentration factor (BCF) of the prey and ingestion rate of fish.

  14. Physicochemical and thermodynamic characterization of N-alkyl-N-methylpyrrolidinium bromides and its aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Zawadzki, Maciej, E-mail: mzawadzki@ch.pw.edu.pl; Królikowska, Marta; Lipiński, Paweł

    2014-08-10

    Highlights: • The aqueous solutions of bromide-based ionic liquids have been studied. • The synthesis and basic thermal characterization of pure IL have been done. • The density, dynamic viscosity, SLE and VLE have been determined. • The experimental data have been correlated using appropriate equations. - Abstract: This work is a continuation of our research of ionic liquids to investigate the physicochemical and thermodynamic properties of (ionic liquid + water) binary mixtures as a novel alternative working pair for the absorption heat pump cycle. In this work, a series of organic salts: N-propyl-N-methyl-pyrrolidinium bromide, [C{sub 1}C{sub 3}PYR]Br; N-butyl-N-methylpyrrolidinium, [C{sub 1}C{sub 4}PYR]Br and N-pentyl-N-methylpyrrolidinium bromide, [C{sub 1}C{sub 5}PYR]Br have been synthesized. The structures of new compounds have been confirmed using NMR spectra and elementary analysis. The basic thermal characterization of pure ILs, including temperature and enthalpy of phase transition (T{sub tr}, Δ{sub tr}H), temperature and enthalpy of melting (T{sub m,} Δ{sub m}H) have been measured using a differential scanning microcalorimetry technique (DSC). Decomposition temperature of the tested ILs were detected by the simultaneous TG/DTA experiments. The effect of temperature on the density (ρ) and dynamic viscosity (η) is reported over a wide temperature range from 298.15 to 343.15 K at ambient pressure. From experimental density data, the excess molar volumes (V{sup E}) were calculated and correlated using Redlich–Kister equation. The isothermal vapour–liquid phase equilibria (VLE) have been measured by an ebulliometric method at wide temperature range from 328.15 to 368.15 K and pressure up to 85 kPa. Experimental data have been correlated by means of NRTL equation. The solid–liquid phase equilibria (SLE) for the tested binary mixtures have been determined over whole composition range using dynamic method. The NRTL equation using parameters

  15. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  16. Tebuconazole photocatalytic degradation kinetics

    OpenAIRE

    Prestes, Thiago de Hermann; Gibbon, Danielle de Oliveira; Lansarin, Marla Azário; Moro, Celso Camilo

    2010-01-01

    The tebuconazole photocatalytic degradation kinetics was studied in a batch reactor using TiO2 (P25-Degussa) as catalyst and a high pressure mercury lamp. The photolysis, adsorption and irradiation effects in the reaction rate were evaluated. Afterward, the suspension catalyst concentration and initial pH to the maximum reaction rate was determined. It was observed that the reaction rate can be approached by a pseudo-first order, with a maximum kinetics constant at 260 mg L-1catalyst concentr...

  17. Synthesis and structure of [2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl] methylphenyltin bromide : A novel triorganotin halide having a configurationally stable chiral tin center

    NARCIS (Netherlands)

    Koten, G. van; Jastrzebski, J.T.B.H.; Wehman, E.; Boersma, J.; Goubitz, K.; Heijdenrijk, D.

    1991-01-01

    Reaction of [2-(4, 4-dimethyl-2-oxazoline)-5-methylphenyl]copper with dimethyltin dibromide or methylphenyltin dibromide affords [2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl]dimethyltin bromide (1) and [2-(4,4-dimethyl-2-oxazoline)-5-methylphenyl]methylphenyltin bromide (2), respectively. The

  18. CARBON PASTE ELECTRODE HEXADECYLTRIMETHYLAMMONIUM BROMIDE MODIFIED NATURAL ZEOLITE FOR CHROMIUM(VI DETECTION

    Directory of Open Access Journals (Sweden)

    Budi Riza Putra

    2013-08-01

    Full Text Available A simple voltammetric technique for quantification of chromium(VI is presented in this work. The technique is based on linear sweep voltammetric reduction Cr(VI on hexadecyltrimethylammonium bromide (HDTMABr modified Lampung zeolite carbon paste electrode. Selected HDTMABr concentration for natural zeolite modification is obtained 200 mM. Working electrode for chromium(VI detection is made by graphite, paraffin oil and HDTMABr modified Lampung zeolite. The effect of supporting electrolyte matrix, pH and also scan rate is also investigated. The calibration curve for chromium(VI detection using the proposed method shows linearity from 0.2 to 1.0 mM with sensitivity, detection and quantification limit, and precision was 0.4294 mM, 3.63 x 10-4 mM, 1.197 x 10-3 mM, 4.49%, respectively.

  19. Increase in mitotic recombination in diploid cells of Aspergillus nidulans in response to ethidium bromide

    Directory of Open Access Journals (Sweden)

    Tânia C.A. Becker

    2003-01-01

    Full Text Available Ethidium bromide (EB is an intercalating inhibitor of topoisomerase II and its activities are related to chemotherapeutic drugs used in anti-cancer treatments. EB promotes several genotoxic effects in exposed cells by stabilising the DNA-enzyme complex. The recombinagenic potential of EB was evaluated in our in vivo study by the loss of heterozygosity of nutritional markers in diploid Aspergillus nidulans cells through Homozygotization Index (HI. A DNA repair mutation, uvsZ and a chromosome duplication DP (II-I were introduced in the genome of tested cells to obtain a sensitive system for the recombinagenesis detection. EB-treated diploid cells had HI values significantly greater than the control at both concentrations (4.0 x 10-3 and 5.0 x 10-3 mM. Results indicate that the intercalating agent is potentially capable of inducing mitotic crossing-over in diploid A. nidulans cells.

  20. Behavior of aqueous Tetrabutylammonium bromide - a combined approach of microscopic simulation and neutron scattering

    CERN Document Server

    Bhowmik, Debsindhu

    2016-01-01

    Aqueous solution of tetrabutylammonium bromide is studied by quasi-elastic neutron scattering, to give information on the dynamic modes involving the ions present. Using a careful combination of two techniques, time-of-flight (TOF) and neutron spin echo (NSE), we de- couple the dynamic information in both the coherently and incoherently scattered signal from this system. We take advantage of the different intensity ratio of the two signals, as detected by each of the techniques, to achieve this decoupling. By using heavy water as the sol- vent, the tetrabutylammonium cation is the only hydrogen-containing species in the system and gives rise to a significant incoherent scattered intensity. The dynamic analysis of the incoherent signal (measured by TOF) leads to a translational diffusion coefficient of the cation as that is in good agreement with previous NMR, neutron scattering and tracer diffusion measurements. The dynamic analysis of the coherent signal observed at wave-vectors < 0.6 angstrom^(-1) (measu...