结核杆菌耐利福定与细菌RNA聚合酶变异关系的研究

选用结核杆菌H_(37)Rv,于体外诱导筛选获得耐利福定(1250μg/ml)菌株,检测了利福定抗结核杆菌活性及其与6种常用抗结核药物的交叉耐药性;以~3H-尿苷进行掺入实验,发现利福定明显抑制~3H-尿苷掺入敏感菌,而对掺入耐药菌则无抑制;提取及分析结核杆菌RNA聚合酶,发现敏感菌酶活性受利福定明显抑制,耐药菌酶活性则未见抑制。结果提示:结核杆菌耐利福定与耐药菌RNA聚合酶改变有关。     

利福定耐药机制探讨—耐药菌及敏感菌的形态学比较

本文报道利福定耐药及敏感细菌的形态学比较。扫描电镜见大肠杆菌耐药菌菌体变短,表面较敏感菌坚实、粗糙;透射电镜观察见耐药菌外膜增厚,电子密度增加。敏感菌以利福定(100μg/ml)处理4h后,光镜下可见菌体变得模糊,出现溶解现象;透射电镜见胞质疏松、核糖体减少并出现空泡。耐药菌经药物处理后无明显改变,但用药时加用EDTA,则出现与敏感菌类似的改变。该结果支持利福定耐药性与细菌包膜屏障改变有关。     

利福霉素的药理与临床

利福霉素的药效动力学目前已知Rif抗菌机制是,抑制细菌RNA聚合酶;而其抗肿瘤作用是,抑制病毒逆向转录酶和DNA聚合酶,这三种酶统称Rif的靶酶。 Rif和细菌RNA聚合酶,容易形成稳定的复合物,使RNA合成停止。利用RNA之放射性前体物之一~3H尿苷掺入菌体速度,可以间接测定菌体RNA聚合酶活性;研究中发现利福定(RFD)和利福平(RFP)与     

槲皮素对血管紧张素Ⅱ致培养乳鼠心肌细胞肥大的抑制作用

目的:研究槲皮素(Quercetin,Que)对血管紧张素Ⅱ(Aug Ⅱ)诱发培养乳鼠心肌细胞肥大的抑制作用及机制。方法:分别用[~3H]胸苷、[~(14)C]尿苷和[~3H]酪氨酸标记测定DNA、RNA和蛋白质合成;用Lowry法测定蛋白质含量;用组蛋白ⅢS、[γ-~(32)P]ATP与蛋白激酶C(PKC)酶液一起保温测定PKC活性;用聚谷氨酸·酪氨酸(4:1)多肽、[γ-~(32)P]ATP与酪氨酸蛋白激酶(TPK)酶液一起保温测TPK活性。结果:Aug Ⅱ作用于心肌细胞24h后,心肌细胞总蛋白含量明显增加(P<0.01),[~(14)C]尿苷和[~3H]酪氨酸掺入量明显增加(P<0.01),而[~3H]胸苷掺入量未见增加(P>0.05);Aug Ⅱ作用30min后,心肌细胞PKC和TPK活性明显增加。Que(1-100μmol/L)能剂量依赖性地抑制Ang Ⅱ所致心肌细胞总蛋白含量、[~(14)C]尿苷和[~3H]酪氨酸掺入量、PKC及TPK活性的增加。结论:Que可抑制Aug Ⅱ致培养乳鼠心肌细胞肥大,该作用与抑制PKC及TPK活性有关。     

碳青霉烯耐药肠杆菌科细菌的耐药机制探讨

目的探讨本院存在的碳青霉烯类耐药肠杆菌科细菌的耐药机制。方法临床检出碳青霉烯类抗菌药物非敏感肠杆菌科细菌6株。改良Hodge实验、EDTA协同试验检、改良三维实验检测其耐药表型;引物特异性PCR法检测其碳青霉烯酶耐药基因及外膜蛋白基因存在情况。结果 1株大肠埃希菌中改良Hodge实验弱阳性,EDTA协同试验阳性,改良三维实验结果可被CLA单独抑制,PCR扩增结果IMP4碳青霉烯酶基因阳性。5株产气肠杆菌改良Hodge实验,阴性3株,阳性两株,EDTA协同试验阴性;改良三维实验中,5株均可被CLO+CLA混合液完全抑制,PCR未扩增出目的基因条带和膜蛋白基因。结论本地区大肠埃希菌的耐药机制可能与IMP4型金属碳青霉烯酶存在有关,产气肠杆菌耐药机制可能与ESBLs和AmpC酶同时存在、膜蛋白表达缺失及其他未检测到的碳青霉稀酶存在有关。     

应用放射性核素检验组织培养基促生长性能的方法

[Dvorakova H et al:J Biol Stand 8(2):107,1980(英文)] 作者根据测定不同条件下培养的人胚肺二倍体细胞中~3H胸苷(或~3H-尿苷)的掺入量,提出了一种新的、快速、可靠的应用放射性核素检验组织培养基促生长性能的方法。     

2008至2010年3年细菌的耐药监测研究

目的分析2008至2010年本院3年临床分离菌的耐药情况。方法用纸片扩散法进行抗菌药物敏感实验,根据CLSI标准用WHONET 5.4软件进行数据分析。结果 3年临床分离的4916株病原菌中,革兰阳性菌占22.7%,革兰阴性菌占77.3%;3年耐甲氧西林金黄色葡萄球菌(MRSA)和凝固酶阴性葡萄球菌(MRCNS)总检出率分别为59.3%,89.5%。大肠埃希菌、肺炎克雷伯菌超广谱β内酰胺酶(ESBLs)总检出率分别为57.5%,34.6%。鲍曼不动杆菌对碳青霉烯类抗菌药物的耐药率有逐年上升趋势,而铜绿假单孢菌则有下降趋势。结论革兰阳性菌对万古霉素、替考拉宁、利奈唑胺均敏感;肠杆菌科细菌对碳青霉烯类药物耐药率较低,但产ESBLs肠杆科细菌较不产ESBLs肠杆科细菌耐药严重;鲍曼不动杆菌对常见抗菌药物的耐药率高,且明显高于铜绿假单孢菌。     

苯噻唑力复霉素作用机理的初步研究

本文报告苯噻唑力复霉素对细菌生物大分子合成及超微结构的影响。该药可明显抑制³H-尿嘧啶核苷掺入金黄色葡萄球菌209 p和大肠杆菌2281的RNA;对²H-亮氨酸掺入细菌蛋白质仅有轻微抑制;对³H-胸嘧啶核苷掺入细菌DNA无抑制作用。说明其作用机理主要是抑制细菌RNA合成。掺入试验还表明金黄色葡萄球菌对苯噻唑力复霉素有比大肠杆菌更高的敏感性。10倍于MIC浓度的苯噻唑力复霉素能使上述两种细菌超微结构明显改变。胞质失去完整结构,出现空泡,核糖体消失,但胞壁仍保存。     

连翘酯苷B对肺炎克雷伯菌外排泵活性的影响

目的研究连翘酯苷B对肺炎克雷伯菌外排泵活性的影响,探讨连翘酯苷B抗菌的作用机制。方法收集10株临床对环丙沙星敏感的肺炎克雷伯菌,用环丙沙星逐步诱导直至细菌MIC不再升高为止,将诱导后菌株作为实验对象,与连翘酯苷B共培养,采用溴化乙锭(EB)蓄积实验比较连翘酯苷B作用前后菌株外排泵活性的变化。结果连翘酯苷B的亚抑菌浓度为512 mg.L-1。连翘酯苷B作用前后的菌株在加入外排泵抑制剂羰基氰氯苯腙(CCCP)后胞内荧光量均明显高于各自未加CCCP的荧光量。有8株细菌不论加或不加CCCP,其经连翘酯苷B作用后的荧光量均高于连翘酯苷B作用前的荧光量;2株细菌在连翘酯苷B作用前后外排泵活性无明显变化。结论外排泵普遍存在于肺炎克雷伯菌中,连翘酯苷B可抑制肺炎克雷伯菌外排泵的活性。     

四环素和青霉素在铜绿假单胞菌中的蓄积动力学研究及能量抑制剂(CCCP)的影响

为证实国内临床分离的铜绿假单胞菌多重耐药菌株中是否存在与其多重耐药有关的主动外排机制 ,本文研究了 3H-四环素和 3H-青霉素在临床多重耐药菌 (2 1、2 6、2 8、435及 M12 5 1)、敏感菌 (172、2 2 3及K799/6 1)以及体外诱导的多重耐药突变株 (172 o c和 2 2 3o c)中的蓄积动力学及能量抑制剂 (Carbonylcyanide m- chlorophenylhydrazone,CCCP)的影响。结果表明两种药物无论是在耐药还是敏感菌中 ,胞内均可在 5～ 10 min内达稳态浓度 ,而且耐药菌中的稳态浓度明显低于敏感菌。当加入 CCCP后 ,耐药菌中的药物浓度明显增加 ,而敏感菌则降低 ,提示在受试的临床耐药菌中存在主动外排机制 ;此外 ,两种抗菌药物在体外诱导多重耐药菌株中的蓄积研究及 CCCP的影响结果与临床耐药菌相似 ,提示获得性多重耐药与天然多重耐药在其多重耐药性产生方面具相同的主动外排机制。     

三尖杉酯碱对肿瘤细胞核苷酸代谢的影响

本文用标记核苷参入艾氏腹水癌细胞各成分以研究三尖杉酯碱对有关的核苷酸代谢的影响。结果表明,该药在抑制DNA合成的同时,使³H-胸腺嘧啶核苷参入酸溶部分明显增加,其中以³H-胸苷三磷酸的增加最为显著。³H-胸苷-磷酸、³H-胸苷二磷酸也有明显增加;但各胸腺嘧啶核苷酸占酸溶部分掺入的百分比与对照组相同。说明三尖杉酯碱不抑制胸腺嘧啶核苷的磷酸化,而抑制脱氧核苷三磷酸到DNA的聚合过程。在³H-尿嘧啶核苷和³H-次黄嘌呤参入实验中,三尖杉酯碱对四种³H-核苷三磷酸及RNA的合成无明显影响。综合核苷三磷酸及脱氧核苷三磷酸的测定结果,表明该药似乎对核糖核苷二磷酸的还原无抑制作用。     

利福定敏感与耐药结核杆菌等细菌的扫描电镜和透射电镜观察

选用结核杆菌、金色葡萄球菌、变形杆菌与大肠杆菌及其相应的体外诱导耐利福定菌株进行扫描电镜与透射电镜观察。结果提示细菌耐利福定后在形态及结构方面发生了改变,但因细菌的种类而异。     

35S]Cyclamate metabolism: incorporation of 35S into proteins of intestinal bacteria in vitro and production of volatile 35S-containing compounds.

1. A washed whole-cell suspension of bacteria prepared from the faeces of rats regularly fed oral cyclamate incorporated 35S into bacterial protein when challenged with [35s]cyclamate. Control preparations showed low-level incorporation of label. 2. Radioactivity was also accounted for as volatile 35S-containing compounds (s), soluble in sodium hydroxide. 3. Addition of cysteine to incubation mixtures inhibited incorporation of 35S into proteins. 4. The results suggest that the bacterial conversion of cyclamate to the suspected bladder carcinogen, cyclohexylamine, is controlled by the prevailing sulphur metabolism of the intestinal bacteria.     

Some biological and biochemical activities of resormycin, a novel herbicidal antibiotic

Biological and biochemical activities of resormycin were studied using unicellular green algae, Selenastrum capricornutum (abbreviated as Selena.), as a test organism. Resormycin inhibited the growth in vitro of Selena. more strongly in the dark than in the light. A weaker but more photo-stable derivative, (+/-)-2,3-dihydro-resormycin, showed more long-lasting activity against Selena. in the light. Resormycin started killing Selena. only after exposure for 2 days and longer, even at high concentrations. Resormycin at concentrations near IC50 rapidly inhibited incorporation of 3H-leu, but not 3H-UR or 3H-TdR, into the TCA insoluble fraction of Selena. Herbicidal activity of resormycin was confirmed using some crops and weeds.     

Changes in thymidine incorporation into tumor cells induced by supernatants of calcium-ionophore-treated macrophages incubated with tumor cells

Thioglycollate-elicited peritoneal M phi of mice were treated with calcium ionophore A23187 prior to incubation with tumor cells. Supernatants prepared from the incubation mixtures were assayed for their effects on incorporation of 3H-thymidine into tumor cells. Significant inhibition of incorporation was observed in most instances. Ingestion of indomethacin in the drinking water for 7 days by prospective M phi donors increased the inhibition by supernatants. The activity of the supernatants was neither specific for the strain and sex of M phi donors nor correlated with the genotype of the tumors. The activity even crossed the species barrier inasmuch as inhibitory supernatants were produced by murine M phi incubated with either murine or human tumor cells. Supernatants derived from murine as well as human tumor cells significantly depressed thymidine incorporation into murine and human tumor cells, although there were some differences in the response of the two kinds of tumor cells. In rare instances, supernatants enhanced, rather than inhibited, thymidine incorporation. Moreover, when supernatants, added to tumor cells, were removed and replaced by fresh medium, in most instances, significant enhancement of thymidine incorporated occurred. The formation of both growth-inhibiting and growth-promoting factors by M phi in the in vitro model used in this study, may explain the dual role of M phi in neoplasia in vivo.     

多相脂质体139抑制DNA、RNA、蛋白质生物合成机制的初步研究

多相脂质体139能够明显抑制癌细胞 DNA 合成,其抑制~3H—TdR 掺入艾氏腹水癌细咆 DNA 合成的曲线为缓慢递增型,表现为可逆性抑制并具有浓度依赖性。药物剂量为1.0mg/ml 时对 RNA 合成呈现轻度抑制并导致癌细胞核酸含量减少。“139”对S—180鼠肿瘤细胞蛋白质合成作用显著,最高抑制率为67.8%。对 RRL 蛋白质合成抑制率为46.8%,这种抑制作用是在延迟了十分钟后表现出来的,说明反应体系中聚核糖核蛋白体上已经开始合成肽链的核糖核蛋白体仍可继续完成肽链的合成,而新的核糖核蛋白体重新由其亚基组合时则受到一定抑制。“139”对肽酰—~3H—嘌吟霉素结合反应并无抑制作用,故不是转肽抑制剂.     

血卟啉衍生物—光辐射对L1210白血病细胞核酸生物合成的影响

本文报道几种血卟啉衍生物—光辐射效应对L1210白血病细胞DNA及RNA生物合成有不同程度的抑制。对DNA生物合成抑制的IC₅₀,HA 308为2.1μg/ml,激光3号为2.5μg/ml,LF-019为3.6μg/ml,Photofrin Ⅱ>5μg/ml,对RNA生物合成抑制的IC₅₀ LF-019为3.7μg/ml,激光3号为5.7 μg/ml,HA 308为8.8 μg/ml,photofrin Ⅱ>10 μg/ml.其中激光3号对DNA聚合酶α的光动力学失活作用也较明显。     

Prevention of thioacetamide-induced liver necrosis by prior administration of substrates of microsomal flavin-containing monooxygenase

Two photostable pyrethroids, deltamethrin and cypermethrin, were tested against fourth instar larvae of a susceptible (S) strain and a resistant (R) strain of Plutella xylostella L. by topical application. Both compounds were very effective against the S strain larvae (LD50 for deltamethrin = 0.0014 micrograms/larva, LD50 for cypermethrin = 0.0046 micrograms/larva, at 48 h). However, the R strain collected from the field was greater than 1600-fold resistant to deltamethrin and greater than 30 000-fold resistant to cypermethrin. Deltamethrin was poorly synergised with piperonyl butoxide in the S strain, but much stronger synergism was obtained in the R strain. The possible reasons for such high levels of resistance and the potential use of synergised pyrethroids in Plutella control programmes are discussed.