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Advances in Research on Resistance Mechanisms of Bacterial Biofilms 预览
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作者 Yanfei LIU Jiande YANG 《农业生物技术:英文版》 CAS 2019年第1期190-193,共4页
A biofilm refers to a group of organized bacteria attached to the surface of living or inanimate objects and surrounded by some macromolecules.It is rich in organic components such as polysaccharides,peptides and phos... A biofilm refers to a group of organized bacteria attached to the surface of living or inanimate objects and surrounded by some macromolecules.It is rich in organic components such as polysaccharides,peptides and phospholipids,greatly increases the resistance of bacteria to antibacterial drugs,and can cause infections in humans and animals.At present,the measure to prevent the infections is to prevent microbial colonies from adhering to the surface of the objects,which will help to improve the therapeutic effect of clinically serious infectious diseases.In addition,the identification and inhibition of biofilm formation genes is also an important research direction to control such infections.In this paper,molecular mechanisms of bacterial biofilm resistance to drugs that has caused widespread concern were summarized. 展开更多
关键词 BIOFILM QUORUM SENSING EFFLUX PUMP Drug resistance Stress response Molecular mechanism
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Stem radial CO2 conductance affects stem respiratory CO2 fluxes in ash and birch trees 预览
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作者 Xiuwei Wang Zijun Mao +1 位作者 M.A.McGuire R.O.Teskey 《林业研究:英文版》 CAS CSCD 2019年第1期21-29,共9页
The CO2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(EA),internal xylem sap transport flux(FT),and storage flux(△S).Adding those fluxes togeth... The CO2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(EA),internal xylem sap transport flux(FT),and storage flux(△S).Adding those fluxes together provides an estimate of actual stem respiration(RS).We know that the relative proportion of CO2 in those fluxes varies greatly among tree species,but we do not yet have a clear understanding of the causes for this variation.One possible explanation is that species differ in stem radial CO2 conductance(gc).A high gc would favor the EA pathway and a low gc would favor the FT pathway.However,gc has only been measured once in situ and only in a single tree species.We measured gc using two methods in stems of Fraxinus mandshurica Rupr.(ash)and Betula platyphylla Suk.(birch)trees in situ,along with RS,EA,FT and △S.Stem radial CO2 conductance was substantially greater in ash trees than in birch trees.Corresponding to that finding,in ash trees over 24 h,EA constituted the entire flux of respired CO2,and FT was negative,indicating that additional CO2,probably transported from the root system via the xylem,was also diffusing into the atmosphere.In ash trees,FT was negative over the entire 24 h,and this study represents the first time that has been reported.The addition of xylem-transported CO2 to EA caused EA to be 9%higher than the actual RS over the diel measurement period.Birch trees,which had lower gc,also had a more commonly seen pattern,with EA accounting for about 80%of the CO2 released from local cell respiration and FT accounting for the remainder.The inorganic carbon concentration in xylem sap was also lower in ash trees than in birch trees:2.7 versus 5.3 mmol L^-1,respectively.Our results indicate that stem CO2 conductance could be a very useful measurement to help explain differences among species in the proportion of respired CO2that remains in the xylem or diffuses into the atmosphere. 展开更多
关键词 STEM CO2 CONDUCTANCE STEM respiration STEM CO2 EFFLUX Transport FLUX STEM temperature SAP flow SAP FLUX density
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Drug interactions of dipeptidyl peptidase 4 inhibitors involving CYP enzymes and P-gp efflux pump 预览
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作者 Naina Mohamed Pakkir Maideen 《世界荟萃分析杂志》 2019年第4期156-161,共6页
Dipeptidyl peptidase 4 (DPP4) inhibitors are oral antidiabetic drugs approved to manage type 2 diabetes mellitus. Saxagliptin is a substrate of CYP3A4/5 enzymes while other DPP4 inhibitors such as sitagliptin, linagli... Dipeptidyl peptidase 4 (DPP4) inhibitors are oral antidiabetic drugs approved to manage type 2 diabetes mellitus. Saxagliptin is a substrate of CYP3A4/5 enzymes while other DPP4 inhibitors such as sitagliptin, linagliptin, gemigliptin and teneligliptin are weak substrates of CYP3A4. DPP4 inhibitors have also been identified as substrates of P-gp. Hence, the drugs inhibiting or inducing CYP3A4/5 enzymes and/or P-gp can alter the pharmacokinetics of DPP4 inhibitors. This review is aimed to identify the drugs interacting with DPP4 inhibitors. The plasma concentrations of saxagliptin have been reported to be increased significantly by the concomitant administration of ketoconazole or diltiazem while no significant interactions between various DPP4 inhibitors and drugs like warfarin, digoxin or cyclosporine have been identified. 展开更多
关键词 Drug interactions SITAGLIPTIN SAXAGLIPTIN LINAGLIPTIN Gemigliptin Teneligliptin VILDAGLIPTIN Anagliptin CYP3A4 P-GP EFFLUX pump
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水力喷射环空加砂压裂喷嘴结构分析与优化 预览
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作者 程新颖 《石油矿场机械》 2019年第2期41-45,共5页
在水力喷射环空加砂压裂射孔过程中,针对喷嘴射流质量低的问题,运用ANSYS-Fluent数值模拟仿真分析方法,对喷嘴重要结构参数进行分析对比,使喷嘴获得最优射流质量。研究结果表明,圆弧形喷嘴的射流质量优于常用的锥直形喷嘴;当喷嘴出口直... 在水力喷射环空加砂压裂射孔过程中,针对喷嘴射流质量低的问题,运用ANSYS-Fluent数值模拟仿真分析方法,对喷嘴重要结构参数进行分析对比,使喷嘴获得最优射流质量。研究结果表明,圆弧形喷嘴的射流质量优于常用的锥直形喷嘴;当喷嘴出口直径4.5~4.8 mm、直柱段长度7~12 mm、入口曲率半径9 mm时,喷嘴可获得最优射流质量。通过对喷嘴结构的优化,可有效提高喷嘴射流质量,为水力喷射环空加砂压裂工艺提供有效的技术支持。 展开更多
关键词 压裂 水力喷射 喷嘴 射流 结构优化
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Alleviation by abscisic acid of Al toxicity in rice bean is not associated with citrate efflux but depends on ABI5-mediated signal transduction pathways
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作者 Wei Fan Jia Meng Xu +6 位作者 Pei Wu Zhi Xin Yang He Qiang Lou Wei Wei Chen Jian Fen Jin Shao Jian Zheng Jian Li Yang 《植物学报:英文版》 SCIE CAS CSCD 2019年第2期140-154,共15页
Under conditions of aluminum(Al) toxicity,which severely inhibits root growth in acidic soils, plants rapidly alter their gene expression to optimize physiological fitness for survival. Abscisic acid(ABA) has been sug... Under conditions of aluminum(Al) toxicity,which severely inhibits root growth in acidic soils, plants rapidly alter their gene expression to optimize physiological fitness for survival. Abscisic acid(ABA) has been suggested as a mediator between Al stress and gene expression, but the underlying mechanisms remain largely unknown. Here,we investigated ABA-mediated Al-stress responses, using integrated physiological and molecular biology approaches.We demonstrate that Al stress caused ABA accumulation in the root apex of rice bean(Vigna umbellata [Thunb.] Ohwi &Ohashi), which positively regulated Al tolerance. However,this was not associated with known Al-tolerance mechanisms. Transcriptomic analysis revealed that nearly one-third of the responsive genes were shared between the Al-stress and ABA treatments. We further identified a transcription factor, ABI5, as being positively involved in Al tolerance. Arabidopsis abi5 mutants displayed increased sensitivity to Al, which was not related to the regulation of AtALMT1 and AtMATE expression. Functional categorization of ABI5-mediated genes revealed the importance of cell wall modification and osmoregulation in Al tolerance, a finding supported by osmotic stress treatment on Al tolerance. Our results suggest that ABA signal transduction pathways provide an additional layer of regulatory control over Al tolerance in plants. 展开更多
关键词 Alleviation by abscisic acid of Al toxicity in rice bean IS not associated with CITRATE EFFLUX BUT depends on ABI5-mediated sign ABA Figure ABI
橙皮素在大鼠体内的吸收机制
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作者 周能 冯海珍 宋健娟 《华西药学杂志》 CAS CSCD 2019年第2期147-151,共5页
目的探讨维拉帕米对橙皮素血浆浓度与肝脏分布的影响,揭示橙皮素的吸收机理。方法将大鼠随机分为3组,第1组灌胃橙皮素的0.5%羧甲基纤维素钠溶液,第2组灌胃橙皮素和维拉帕米的0.5%羧甲基纤维素钠溶液,第3组作为对照组,给药后于1、2、4 h... 目的探讨维拉帕米对橙皮素血浆浓度与肝脏分布的影响,揭示橙皮素的吸收机理。方法将大鼠随机分为3组,第1组灌胃橙皮素的0.5%羧甲基纤维素钠溶液,第2组灌胃橙皮素和维拉帕米的0.5%羧甲基纤维素钠溶液,第3组作为对照组,给药后于1、2、4 h三个时间点,取血浆及肝脏,经处理后,用HPLC测定药物的含量。结果维拉帕米+橙皮素组与橙皮素组的血药浓度与肝脏含药量存在显著性差异。结论橙皮素以缀合物被吸收,且以原型在肝脏分布,维拉帕米可显著提高橙皮素的吸收及肝脏分布量。维拉帕米抑制p-糖蛋白从而抑制橙皮素外排是其促进吸收的原因之一。 展开更多
关键词 橙皮素 维拉帕米 血浆浓度 组织分布 高效液相色谱 药动学 吸收机制 P-糖蛋白 外排
Si/As调控苗期水稻吸收、外排和转运砷的研究 预览
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作者 付洁 陈苗苗 +3 位作者 樊利敏 孙洪欣 薛培英 刘文菊 《水土保持学报》 CSCD 北大核心 2019年第4期370-376,共7页
通过生物模拟法,将水稻幼苗分别暴露于含有10μmol/L无机三价砷As(Ⅲ)或五价砷As(V)的营养液中12,24,48h,探究硅砷摩尔比(Si/As为0∶1,100∶1和200∶1)对苗期水稻吸收、外排、转运和累积砷的影响。结果表明,水稻暴露于含As(Ⅲ)营养液中1... 通过生物模拟法,将水稻幼苗分别暴露于含有10μmol/L无机三价砷As(Ⅲ)或五价砷As(V)的营养液中12,24,48h,探究硅砷摩尔比(Si/As为0∶1,100∶1和200∶1)对苗期水稻吸收、外排、转运和累积砷的影响。结果表明,水稻暴露于含As(Ⅲ)营养液中12h,与Si/As为0∶1相比,Si/As为200∶1的处理使水稻的As(Ⅲ)吸收速率降低30.7%(P<0.05),且随着暴露时间的延长,水稻对As(Ⅲ)的吸收速率逐渐降低,不同Si/As对其吸收速率的影响也减弱。处理48h,100∶1和200∶1的Si/As均降低水稻根部As(Ⅲ)向茎叶的转移系数,较Si/As为0∶1分别降低51.2%和56.9%,同时水稻地上部As(Ⅲ)含量比Si/As为0∶1的处理分别降低50.7%和67.2%;暴露在As(V)营养液中12h,Si/As为100∶1促进水稻对As(V)的吸收,增幅高达82.3%,但暴露24h,Si/As为200∶1则抑制水稻根系对As(V)的吸收,以及As(Ⅲ)的外排和As(Ⅲ)由水稻根系向茎叶的转运,降幅分别为28.0%,41.9%和39.9%。暴露48h时,Si/As为200∶1的水稻As(Ⅲ)转移系数较Si/As为100∶1的处理降低57.9%,并且处理24,48h时,Si/As为100∶1和200∶1水稻地上部As(Ⅲ)含量显著降低53.6%和75.0%,25.0%和52.8%。此外,水稻根系对As(V)的吸收与As(Ⅲ)的外排之间呈极显著正相关关系(r=0.921,P<0.01),该关系不受Si/As和暴露时间的影响。无论是As(Ⅲ)或As(V)处理,在12~48h的暴露时间内,Si/As为200∶1显著抑制砷的吸收、As(Ⅲ)的外排和As(Ⅲ)在水稻体内的转运。 展开更多
关键词 硅/砷摩尔比 水稻 吸收 外排 转运 无机砷
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Design,synthesis and biological evaluation of selective survivin inhibitors 预览
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作者 Min Xiao Yi Xue +4 位作者 Zhongzhi Wu Zi-Ning Lei Jin Wang Zhe-Sheng Chen Wei Li 《生物医学研究杂志:英文版》 CAS CSCD 2019年第2期82-100,共19页
The differential distribution between cancer cells and normal adult tissues makes survivin a very attractive cancer drug target.We have previously reported a series of novel selective survivin inhibitors with the most... The differential distribution between cancer cells and normal adult tissues makes survivin a very attractive cancer drug target.We have previously reported a series of novel selective survivin inhibitors with the most potent compound MX106 reaching nanomolar activity in several cancer cell lines.Further optimization of the MX106 scaffold leads to the discovery of more potent and more selective survivin inhibitors.Various structural modifications were synthesized and their anticancer activities were evaluated to determine the structure activity relationships for this MX106 scaffold.In vitro anti-proliferative assays using two human melanoma cell lines showed that several new analogs have improved potency compared to MX106.Very interestingly,these new analogs generally showed significantly higher potency against P-glycoprotein overexpressed cells compared with the corresponding parental cells,suggesting that these compounds may strongly sensitize tumors that have high expressions of the Pglycoprotein drug efflux pumps.Western blotting analysis confirmed that the new MX106 analogs maintained their mechanism of actions by selectively suppressing survivin expression level among major inhibitors of apoptotic proteins and induced strong apoptosis in melanoma tumor cells. 展开更多
关键词 SELECTIVE SURVIVIN INHIBITORS structure activity relationships melanoma human EPIDERMOID carcinoma colorectal cancer P-GLYCOPROTEIN drug EFFLUX pumps
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Low nutrient levels as drinking water conditions can reduce the fitness cost of efflux pump-mediated ciprofloxacin resistance in Pseudomonas aeruginosa
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作者 Wenfang Lin Kun Wan +3 位作者 Jie Zeng Jingjing Li Xi Li Xin Yu 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第9期123-132,共10页
The long-term persistence of antibiotic resistance in the environment, especially in drinking water, is a public health concern. Expression of an efflux pump, an important mechanism of resistance to antibiotics, usual... The long-term persistence of antibiotic resistance in the environment, especially in drinking water, is a public health concern. Expression of an efflux pump, an important mechanism of resistance to antibiotics, usually confers a fitness cost in bacteria. In this study, we aimed to determine why antibiotic resistance conferred by overexpression of an efflux pump persisted in low-nutrient environments(TOC < 10 mg/L) such as drinking and source water in which antibiotic selective pressure might be very low or even absent.Competition experiments between wild-type Pseudomonas aeruginosa and ciprofloxacinresistant mutants revealed that the fitness cost of ciprofloxacin resistance significantly decreased(p < 0.05) under low-nutrient(0.5 mg/L total organic carbon(TOC)) relative to high-nutrient(500 mg/L TOC) conditions. Mechanisms underlying this fitness cost were analyzed. The mexD gene expression in resistant bacteria(cip3 strain) was significantly lower(p < 0.05) in low-nutrient conditions, with 10 mg/L TOC((8.01 ± 0.82)-fold), than in high-nutrient conditions, with 500 mg/L TOC((48.89 ± 4.16)-fold). Moreover, rpoS gene expression in resistant bacteria((1.36 ± 0.13)-fold) was significantly lower(p < 0.05) than that in the wild-type strain((2.78 ± 0.29)-fold) under low-nutrient conditions(10 mg/L TOC),suggesting a growth advantage. Furthermore, the difference in metabolic activity between the two competing strains was significantly smaller(p < 0.05) in low-nutrient conditions(5 and 0.5 mg/L TOC). These results suggest that nutrient levels are a key factor in determining the persistence of antibiotic resistance conferred by efflux pumps in the natural environment with trace amounts or no antibiotics. 展开更多
关键词 EFFLUX pumps Antibiotic RESISTANCE Fitness cost LOW NUTRIENT nfxB mutation CIPROFLOXACIN RESISTANCE
Different structures of berberine and five other protoberberine alkaloids that affect P-glycoprotein-mediated efflux capacity
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作者 Yi-ting Zhang Yu-qi Yu +6 位作者 Xiao-xia Yan Wen-jie Wang Xiao-ting Tian Le Wang Wei-liang Zhu Li-kun Gong Guo-yu Pan 《中国药理学报:英文版》 SCIE CAS CSCD 2019年第1期133-142,共10页
Berberine,berberrubine,thalifendine,demethyleneberberine,jatrorrhizine,and columbamine are six natural protoberberine alkaloid (PA)compounds that display extensive pharmacological'properties and share the same pro... Berberine,berberrubine,thalifendine,demethyleneberberine,jatrorrhizine,and columbamine are six natural protoberberine alkaloid (PA)compounds that display extensive pharmacological'properties and share the same protoberberine molecular skeleton with only slight substitution differences.The oral delivery of most PAs is hindered by their poor bioavailability,which is largely caused by P-glycoprotein (P-gp)-mediated drug efflux.Meanwhile,P-gp undergoes large-scale conformational changes (from an inward-facing to an outward-facing state)when transporting substrates,and these changes might strongly affect the P-gp-binding specificity.To confirm whether these six compounds are substrates of P-gp,to investigate the differences in efflux capacity caused by their trivial structural differences arid to reveal the key to increasing their binding affinity to P-gp,we conducted a series of in vivo,in vitro,and in silico assays.Here,we first confirmed that all six compounds were substrates of P-gp by comparing the drug concentrations in wild-type and P-gp-knockout mice in vivo.The efflux capacity (net efflux)ranked as berberrubine >berberine > columbamine ~jatrorrhizine >thalifendine >demethyleneberberine based on in vitro transport studies in Caco-2 monolayers. Using molecular dynamics simulation and molecular docking techniques,we determined the transport pathways of the six compounds and their binding affinities to P-gp.The results suggested that at the early binding stage,different hydrophobic and electrostatic interactions collectively differentiate the binding affinities of the compounds to P-gp,whereas electrostatic interactions are the main determinant at the late release stage.In addition to hydrophobic interactions,hydrogen bonds play an important role in discriminating the binding affinities. 展开更多
关键词 P-GLYCOPROTEIN PROTOBERBERINE ALKALOID BERBERINE binding AFFINITY EFFLUX
施硼对水稻幼苗吸收和分泌砷的影响
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作者 朱毅 孙国新 +2 位作者 陈正 胡莹 郑瑞伦 《环境科学》 CSCD 北大核心 2018年第7期3400-3408,共9页
通过3组水培试验研究了营养液不同供硼(B)浓度和叶面施B对水稻(Oryza sativa L.)幼苗吸收、转运和分泌砷(As)的影响.在10μmol·L-1三价砷[As(Ⅲ)]或五价砷[As(Ⅴ)]处理下,营养液B浓度没有显著影响水稻体内As(Ⅲ)、As... 通过3组水培试验研究了营养液不同供硼(B)浓度和叶面施B对水稻(Oryza sativa L.)幼苗吸收、转运和分泌砷(As)的影响.在10μmol·L-1三价砷[As(Ⅲ)]或五价砷[As(Ⅴ)]处理下,营养液B浓度没有显著影响水稻体内As(Ⅲ)、As(Ⅴ)和总As的含量、转移系数和根吸收效率.叶面施B使得水稻幼苗地上部的B含量显著增加15.8倍,使得As(Ⅴ)处理条件下的根部As含量和As根吸收效率分别显著降低20.9%和18.0%,As(Ⅲ)处理条件下的根部As含量和As根吸收效率分别降低12.6%和13.8%(P〈0.05),而地上部As含量降低不显著(P〉0.05).在As(Ⅴ)处理下,叶面施B使根部B含量显著降低达47.1%,而As(Ⅲ)处理下根部B含量无显著变化.As(Ⅴ)处理下的水稻根部B含量平均比As(Ⅲ)处理高85.3%(P〈0.05).叶面施B后,As(Ⅴ)处理下水稻根部中总As含量和As(Ⅴ)含量均与根部B含量呈显著正相关(P〈0.05).As(Ⅲ)预处理后水稻幼苗根系外泌的As总量比As(Ⅴ)预处理高105.2%.叶面施B使As(Ⅲ)预处理水稻的As外泌量增加14.0% ~16.9%(P〉0.05),对As(Ⅴ)预处理的水稻As外泌无影响.水稻根部有45.9% ~70.7%的As可以在1周内被外排到生长介质中.结果表明,营养液供B浓度为As浓度的4倍时仍不能减少水稻幼苗对As的吸收累积,而叶面施B有助于减少水稻对As的吸收.B通道不是As(Ⅲ)进入水稻根系的主要途径;As(Ⅴ)在水稻中的迁移分配机制可能与B的迁移运输有关. 展开更多
关键词 三价砷 五价砷 外泌 吸收 水稻
ChrA基因在大肠杆菌中的表达及其抗铬特性 预览
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作者 周思敏 董兰岚 +1 位作者 何元 肖虹 《南方医科大学学报》 CSCD 北大核心 2017年第10期1290-1295,共6页
目的研究铬(Ⅵ)转运蛋白编码基因ChrA工程菌的抗铬(Ⅵ)能力及铬(Ⅵ)抗性机制。方法以沙雷氏菌S2基因组作为模板,PCR扩增ChrA基因,连接表达载体pET-28a(+),转化至E.coli BL21表达。测定ChrA工程菌的Cr(Ⅵ)抗性、摄取能力和外... 目的研究铬(Ⅵ)转运蛋白编码基因ChrA工程菌的抗铬(Ⅵ)能力及铬(Ⅵ)抗性机制。方法以沙雷氏菌S2基因组作为模板,PCR扩增ChrA基因,连接表达载体pET-28a(+),转化至E.coli BL21表达。测定ChrA工程菌的Cr(Ⅵ)抗性、摄取能力和外排Cr(Ⅵ)能力,探索铬(Ⅵ)负载时间、含氧阴离子(硫酸盐、钼酸盐、钒酸盐、钨酸盐)和呼吸抑制剂(缬氨霉素、寡霉素、CN-、NADH)对其抗Cr(Ⅵ)能力的影响,分析ChrA蛋白转运Cr(Ⅵ)的机制路径。结果成功构建pET-28a(+)-ChrA工程菌,并表达出膜蛋白ChrA;ChrA工程菌的Cr(Ⅵ)吸收能力低于对照株(P〈0.05),Cr(Ⅵ)外排能力高于对照株(P〈0.05);工程菌在50 mg/L Cr_2O_7~(2-)中负载30 min,新鲜溶液中释放10 min后,菌体中的Cr(Ⅵ)外排量达到20%,但随着铬(Ⅵ)负载时间延长,外排量逐渐减少;工程菌外排能力受含氧阴离子硫酸盐和钼酸盐显著抑制(P〈0.05),推测ChrA蛋白是通过硫酸盐通道运输Cr(Ⅵ),而钨酸盐和钒酸盐对其Cr(Ⅵ)外排无明显抑制或促进作用;在抑制剂类别中,K+载体缬氨霉素、CN-显著性抑制其Cr(Ⅵ)外排,NADH促进其Cr(Ⅵ)外排(P〈0.05),而寡霉素无明显抑制或促进作用,表明ChrA蛋白外排铬(Ⅵ)是利用质子动力通过细胞膜化学渗透作用把铬离子泵出细胞外。结论 ChrA蛋白具有将Cr(Ⅵ)从胞浆转运至胞外的作用,ChrA的表达提高了大肠杆菌的铬(Ⅵ)抗性能力。 展开更多
关键词 ChrA 工程菌 铬(Ⅵ)抗性 外排
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Effects of two efflux pump inhibitors on the drug susceptibility of Riemerella anatipestifer isolates from China 预览
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作者 LI Ya-fei JIANG Hong-xia +6 位作者 XIANG Rong SUN Na ZHANG Ya-nan ZHAO Li-qing GU Peng WANG Li-qiao ZENG Zhen-ling 《农业科学学报:英文版》 SCIE CAS CSCD 2016年第4期929-933,共5页
The objective of this study was to verify the supposition that efflux might be involved in the drug resistance of Riemerella anatipestifer isolates.Two broad-spectrum efflux pump inhibitors,carbonyl cyanide 3-chloroph... The objective of this study was to verify the supposition that efflux might be involved in the drug resistance of Riemerella anatipestifer isolates.Two broad-spectrum efflux pump inhibitors,carbonyl cyanide 3-chlorophenylhydrazone(CCCP)and Phe-Arg-β-naphthylamide(PAβN),on the contribution of minimum inhibitory concentrations of amikacin,streptomycin,chloramphenicol,tetracycline,ceftriaxone,ceftazidime,nalidixic acid,levofloxacin,enrofloxacin,as well as ciprofloxacin against 69 clinical R.anatipestifer isolates were investigated.We first reported that the two efflux pump inhibitors could restore the antimicrobial susceptibility of R.anatipestifer isolates.It is suggested that active efflux system is possible to be linked with the development of resistance in R.anatipestifer isolates. 展开更多
关键词 鸭疫里默氏杆菌 耐药菌株 外排泵 抑制剂 药物敏感性 中国 丁胺卡那霉素 最低抑菌浓度
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轮叶黑藻对无机砷的吸收和释放 预览
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作者 薛培英 陈苗苗 +2 位作者 耿丽平 赵全利 王亚琼 《农业环境科学学报》 CAS CSCD 北大核心 2015年第10期1853-1857,共5页
采用室内模拟试验,通过对无机砷的吸收和释放研究,结合砷形态测定,研究了沉水植物轮叶黑藻[Hydrilla verticillata(L.f.)Royle]对无机砷(As)的吸收和释放能力。结果表明:黑藻对五价砷(AsⅤ)和三价砷(AsⅢ)均具有较高的吸收速率(最大吸... 采用室内模拟试验,通过对无机砷的吸收和释放研究,结合砷形态测定,研究了沉水植物轮叶黑藻[Hydrilla verticillata(L.f.)Royle]对无机砷(As)的吸收和释放能力。结果表明:黑藻对五价砷(AsⅤ)和三价砷(AsⅢ)均具有较高的吸收速率(最大吸收速率分别为105、96.1 nmol·g-1DW·min-1),且对AsⅤ和AsⅢ的最大吸收速率差异不显著(P>0.05)。无论暴露于AsⅤ还是AsⅢ溶液中,黑藻体内均以AsⅢ形态为主(>90%),而且黑藻可以将外界AsⅤ迅速吸收进入体内并还原为AsⅢ,并快速将AsⅢ释放到外部溶液中(AsⅢ释放量占AsⅤ吸收量的53%)。加磷(P)显著抑制黑藻对AsⅤ的富集(体内主要存在形态AsⅢ为不加P时的1/3),进一步导致溶液中的砷形态以AsⅤ为主(占总砷含量90%),加P不影响黑藻对AsⅢ的富集;植物螯合素(PCs)合成抑制剂丁胱亚磺酰亚胺(BSO)显著抑制黑藻对AsⅤ和AsⅢ的吸收,无论是AsⅤ还是AsⅢ处理,黑藻体内AsⅢ含量均降低,分别为对照处理的8%和10%,且溶液中砷形态含量与对照相比差异不显著(P>0.05)。 展开更多
关键词 轮叶黑藻 吸收 释放
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多种方法测定白色念珠菌对罗丹明6G的吸收和泵出
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作者 郭琼杰 马强 +1 位作者 王宝泉 王莉 《中国热带医学》 CAS 2015年第8期920-923,共4页
目的探索白色念珠菌对罗丹明6G的吸收和泵出的测定意义,并对测定方法进行总结。方法借助2株白色念珠菌敏感株和2株白色念珠菌耐药株,采用多功能微板检测仪、流式细胞仪、荧光显微镜三种仪器,通过定量、半定量和定性的方法测定不同敏... 目的探索白色念珠菌对罗丹明6G的吸收和泵出的测定意义,并对测定方法进行总结。方法借助2株白色念珠菌敏感株和2株白色念珠菌耐药株,采用多功能微板检测仪、流式细胞仪、荧光显微镜三种仪器,通过定量、半定量和定性的方法测定不同敏感性白色念珠菌对罗丹明6G的吸收和泵出,对定量与半定量结果进行T检验,并与定性结果进行比较。结果不同敏感性白色念珠菌对罗丹明6G的吸收基本一致,实验用耐药菌对罗丹明6G的泵出比敏感菌多;以多功能微板检测仪测定结果为标准,流式细胞仪测定结果与之的一致性为83.3%,荧光显微镜观察结果与之的一致性为91.7%,三种方法具有一致性。结论白色念珠菌对罗丹明6G的吸收和泵出的测定可以为研究新型抗真菌成分的作用机制和真菌耐药逆转剂的作用机制提供工具菌株和可能的研究方向,应根据实验目的和条件选择适当的测定方法。 展开更多
关键词 白色念珠菌 罗丹明6G 吸收 泵出
8-异丙胺亚甲基橙皮素(IPHP)在Caco-2细胞模型上跨膜转运的研究 预览 被引量:2
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作者 胡婷婷 黄成 +3 位作者 孟晓明 陈昭琳 沈陈林 李俊 《中国药理学通报》 CAS CSCD 北大核心 2015年第6期769-774,共6页
目的利用Caco-2细胞模型研究8-异丙胺亚甲基橙皮素(IPHP)在小肠吸收转运的机制。方法在Caco-2细胞模型上进行IPHP的跨膜转运实验,探讨药物浓度、p H、温度、P-gp抑制剂维拉帕米、MRP2抑制剂MK-571和丙磺舒对IPHP在体外细胞模型上跨膜... 目的利用Caco-2细胞模型研究8-异丙胺亚甲基橙皮素(IPHP)在小肠吸收转运的机制。方法在Caco-2细胞模型上进行IPHP的跨膜转运实验,探讨药物浓度、p H、温度、P-gp抑制剂维拉帕米、MRP2抑制剂MK-571和丙磺舒对IPHP在体外细胞模型上跨膜转运的影响。结果 IPHP在Caco-2细胞模型上的转运具有一定的浓度依赖性,IPHP不同浓度从A侧到B侧的渗透系数Papp(AP-BL)(×10^-5)分别为:(2.21±0.200)、(3.56±0.306)、(3.81±0.179)、(4.23±0.229)、(4.17±0.262)cm·s^-1,B侧到A侧的渗透系数Papp(BL-AP)(×10^-5)分别为:(3.57±0.209)、(4.51±0.113)、(4.97±0.229)、(5.24±0.550)、(5.07±0.557)cm·s^-1,外排率分别为:1.61、1.26、1.3、1.23、1.21。温度和p H对其转运均有影响,而P-gp抑制剂对于IPHP的转运没有明显的影响,MRP2抑制剂在一定程度上增加了IPHP的转运量(P〈0.05)。结论 IPHP在Caco-2细胞模型上的转运方式主要是被动扩散,且其转运不受P-gp外排蛋白影响,而外排蛋白MRP2可能参与了IPHP的外排转运。 展开更多
关键词 IPHP CACO-2细胞 吸收 外排 渗透系数 被动扩散 高效液相色谱
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射吸式液体燃料割炬性能影响因素分析 预览
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作者 王通 李继光 《科技创新与生产力》 2014年第4期75-76,共2页
基于射吸式气体割炬易造成回火的状况,为了减小操作过程中的不利因素,研制了一种射吸式液体燃料割炬。通过介绍该类割炬关键部件射流泵的工作原理,分析了工作性能影响因素,包括设计参数、装配质量和操作方法等,最终得到最佳设计参数及... 基于射吸式气体割炬易造成回火的状况,为了减小操作过程中的不利因素,研制了一种射吸式液体燃料割炬。通过介绍该类割炬关键部件射流泵的工作原理,分析了工作性能影响因素,包括设计参数、装配质量和操作方法等,最终得到最佳设计参数及操作方法,以提高工作效率及生产过程的安全性。 展开更多
关键词 射流 割炬 工作性能
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体外诱导嗜水气单胞菌对喹诺酮类耐药及其耐药机制研究 预览 被引量:5
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作者 邓玉婷 薛慧娟 +5 位作者 姜兰 谭爱萍 吴雅丽 王伟利 罗理 赵飞 《华南农业大学学报》 CAS CSCD 北大核心 2014年第1期12-16,共5页
【目的】探讨在亚抑菌浓度喹诺酮类药物培养后,嗜水气单胞菌Aeromonashydrophila对喹诺酮类的药物敏感性变化及其耐药机制.【方法】以对喹诺酮类敏感的临床分离嗜水气单胞菌菌株和标准菌ATCC7966为研究对象,分别在含亚抑菌浓度萘啶酸... 【目的】探讨在亚抑菌浓度喹诺酮类药物培养后,嗜水气单胞菌Aeromonashydrophila对喹诺酮类的药物敏感性变化及其耐药机制.【方法】以对喹诺酮类敏感的临床分离嗜水气单胞菌菌株和标准菌ATCC7966为研究对象,分别在含亚抑菌浓度萘啶酸(NAL)和环丙沙星(CIP)的培养基上逐步诱导培养.提取诱导菌的DNA,PCR扩增其gryA和parC基因,测序分析其喹诺酮类耐药决定区(QRDR)突变情况;测定诱导菌对诱导药物和11种非诱导药物的最小抑菌浓度(MIC)及添加外排泵抑制剂羰基氰化氯苯腙(CCCP)后的MIC,分析其敏感性变化与基因突变、外排作用的关系.【结果和结论】诱导后菌株对萘啶酸和环丙沙星的MIC分别提高了1024和64000倍,对非诱导药物也有不同程度提高;当萘啶酸和环丙沙星诱导浓度分别达到16和32μg/mL或以上后,诱导菌株gyrA基因编码的氨基酸分别发生Asp87→Tyr和Ser83→Arg的变化,但两者parC基因编码的氨基酸均没有发生突变;添加CCCP后,只有氟喹诺酮类药物的MIC值略有下降,提示嗜水气单胞菌对喹诺酮类耐药存在靶基因突变及主动外排作用等多种耐药机制. 展开更多
关键词 嗜水气单胞菌 喹诺酮类 体外诱导 基因突变 外排作用
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小檗碱在Caco-2细胞单层模型中吸收和外排机制的研究 预览 被引量:4
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作者 陈健龙 张玉玲 +3 位作者 董宇 蔡广知 贡济宇 崔翰明 《中成药》 CAS CSCD 北大核心 2014年第4期719-723,共5页
目的利用Caco-2细胞单层模型研究小檗碱的双向转运和外排动力学机制。方法超高液相色谱法测定Tran-swell^TM中供给池和接受池中小檗碱的浓度,计算其表观渗透系数(Papp),分析P-糖蛋白外排泵(P-gP)的作用。结果不同浓度小檗碱由肠... 目的利用Caco-2细胞单层模型研究小檗碱的双向转运和外排动力学机制。方法超高液相色谱法测定Tran-swell^TM中供给池和接受池中小檗碱的浓度,计算其表观渗透系数(Papp),分析P-糖蛋白外排泵(P-gP)的作用。结果不同浓度小檗碱由肠腔面到基底面(A→B面)的Papp约在(2-3)×10^-6,吸收量与浓度成线性关系,而由基底面到肠腔面(B→A面)的Papp约在(2-3)X10^-5,约是A—B面的8~10倍,给予P→gP抑制剂维拉帕米后B→A面的外排转运明显减低,A→B面的吸收明显增加。结论小檗碱是以被动扩散为主要转运方式被小肠上皮细胞摄取和转运,属吸收中等的药物,且存在P-糖蛋白介导的外排机制。 展开更多
关键词 小檗碱 CACO-2细胞模型 吸收 双向转运 外排
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微生物对锑的代谢机制研究进展 预览 被引量:5
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作者 李明顺 李洁 王革娇 《华中农业大学学报》 CAS CSCD 北大核心 2013年第5期15-19,共5页
锑(Sb)是一种自然界普遍存在的剧毒重金属,随着工业生产的日趋发展,我国部分地区土壤、水体及农产品受到严重的锑污染。作为环境污染物,锑中毒会导致人类心肌衰竭,肝坏死等疾病。自然界中的某些生物,特别是微生物却可以在极高锑浓度... 锑(Sb)是一种自然界普遍存在的剧毒重金属,随着工业生产的日趋发展,我国部分地区土壤、水体及农产品受到严重的锑污染。作为环境污染物,锑中毒会导致人类心肌衰竭,肝坏死等疾病。自然界中的某些生物,特别是微生物却可以在极高锑浓度下生长,甚至可以利用这种元素作为能源物质,因此,微生物在锑的地球物质循环中起着重要的作用。研究生物对锑的代谢机制,对于保护环境与人体健康具有重要的现实意义。本文对锑在环境中的分布、污染状况、微生物对锑的代谢以及生物修复等方面的研究现状进行了综述。同时建议今后应加强以下三方面的研究:(1)筛选更多抗锑微生物或氧化锑的微生物;(2)发掘更多锑抗性基因或氧化基因;(3)开发锑污染土壤及水体的微生物修复技术。 展开更多
关键词 微生物 代谢 外排 氧化
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