Structural Changes and Differentially Expressed Genes in Pseudomonas aeruginosa Exposed to Meropenem-Ciprofloxacin Combination

The effect of a meropenem-ciprofloxacin combination (MCC) on the susceptibility of multidrug-resistant (MDR) Pseudomonas aeruginosa (MRPA) clinical isolates was determined using checkerboard and time-kill curve techniques. Structural changes and differential gene expression that resulted from the synergistic action of the MCC against one of the P. aeruginosa isolates (1071-MRPA]) were evaluated using electron microscopy and representational difference analysis (RDA), respectively. The differentially expressed, SOS response-associated, and resistance-associated genes in 1071-MRPA exposed to meropenem, ciprofloxacin, and the MCC were monitored by quantitative PCR. The MCC was synergistic against 25% and 40.6% of MDR P. aeruginosa isolates as shown by the checkerboard and time-kill curves, respectively. The morphological and structural changes that resulted from the synergistic action of the MCC against 1071-MRPA were a summation of the effects observed with each antimicrobial alone. One exception included outer membrane vesicles, which were seen in a greater amount upon ciprofloxacin exposure but were significantly inhibited upon MCC exposure. Cell wall- and DNA repair-associated genes were differentially expressed in 1071-MRPA exposed to meropenem, ciprofloxacin, and the MCC. However, some of the RDA-detected, resistance-associated, and SOS response-associated genes were expressed at significantly lower levels in 1071-MRPA exposed to the MCC. The MCC may be an alternative for the treatment of MDR P. aeruginosa. The effect of this antimicrobial combination may be not only the result of a summation of the effects of meropenem and ciprofloxacin but also a result of differential action that likely inhibits protective mechanisms in the bacteria.     

Activity of megazol, a trypanocidal nitroimidazole, is associated with DNA damage

DNA damage associated with the trypanocidal activity of megazol [2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole] was shown in experiments in which DNA repair-deficient RAD51(-/-) Trypanosoma brucei mutants were found to be hypersensitive to the drug. Parasites resistant to megazol were selected and showed modest cross-resistance to other trypanocides, although neither drug efflux nor changes to intracellular thiols correlated with resistance.     

自体骨髓来源内皮祖细胞移植对移植静脉桥血管再内皮化及内膜增生的影响

目的:已有实验研究证明,移植骨髓来源内皮祖细胞可以促进球囊损伤后血管内皮的修复及抑制内膜的增生.那么移植骨髓来源内皮祖细胞对自体静脉移植术后静脉血管内皮修复和内膜增生是否起同样的作用?观察自体骨髓来源内皮祖细胞移植对自体静脉移植术后静脉桥血管再内皮化及内膜增生的作用。方法:实验于2007-01/08在北华大学附属医院内科实验室完成。实验室级别:P2级。①实验材料:6～8月龄雄性新西兰大白兔由解放军第二军医大学实验动物中心提供.体质量(2.5±0.5)kg,清洁级,实验过程中对动物处置符合动物伦理学标准。②实验方法:抽取成年兔骨髓分离制备骨髓单个核细胞,体外扩增法培养出骨髓来源内皮祖细胞.在培养第7天通过Ac-Dil-LDL、FITC-BS-1双染色及流式细胞仪检测CD34、CD133、FIK-1表达进行细胞鉴定,应用DAPI荧光染料体外标记培养7 d的骨髓来源内皮祖细胞、将成年新西兰大白兔23只随机分为细胞移植组(n=13)和对照组(n=10)进行自体左颈外静脉、颈总动脉移植术,在建模后第3天将DAPI标记的骨髓来源内皮祖细胞悬液经耳缘静脉植入细胞移植组动物体内,埘照组植入等量的PBS液③实验评估:细胞移植后4周.观察兔静脉移植段血管性及内膜厚度。结果:23只免均进入结果分析,无脱落:①通过体外扩增法培养的骨髓来源内皮组细胞,培养至7 d可见AC-Dil-LDI及FITC-BS-1双染色阳性细胞并表达CD34、CD133及FIK-1。②在呈绿荧光染色的血管内皮中可见有部分不均匀的散发蓝色荧光(DAPI标记细胞的细胞核)。③细胞移植组兔静脉血管内皮有DAPI标记的细胞.且内膜厚度明显低于对照组(P<0.05)结论:自体骨髓来源的内皮祖细胞移植可以促进损伤部位血管内皮的修复.并抑制内膜的过度增生。     

Structuring a safer donor-replacement program

BACKGROUND: Replacement donors are more likely than volunteer donors to have positive or abnormal tests for transfusion-transmissible disease. In an effort to increase the donor pool, workers sought to identify a safer replacement-donor subgroup that may be acceptable for routine donations. STUDY DESIGN AND METHODS: In a retrospective review and cohort study, the replacement-donor effect was separated from the new- donor effect. The relative effect the replacement donor has on the risk of transfusion-transmissible diseases, donor retention, and frequency of returning donations was then quantified by comparison against the effect of repeat volunteer donors. RESULTS: The replacement donor had 3.1 times the risk and 0.72 times the donor retention rate and made 0.81 times as many returning donations as the repeat volunteer donor. The figures for the new-donor effect were similar. The two risks were additive, making a new replacement donor particularly hazardous. If replacement donations only from repeat replacement donors were considered, the donor risk and the number of donations per returning donor were made comparable to those for the general (combined) volunteer donor. CONCLUSION: The negative effect of the replacement donor is similar in magnitude to that of the new volunteer donor. A replacement-donation program targeting repeat replacement donors has an acceptable risk profile and may be a valuable adjunct to the collection of blood from general volunteer donors.     

Preserved regulation of renal perfusion pressure by small and intermediate conductance K<Subscript>Ca</Subscript> channels in hypertensive mice with or without renal failure

The purpose of this study was to assess, in the murine kidney, the mechanisms underlying the endothelium-dependent control of vascular tone and whether or not, in a severe model of hypertension and renal failure, K_Ca channels contribute to its regulation. Wild-type (BL) and double-transgenic female mice expressing human angiotensinogen and renin (AR) genes received either control or a high-salt diet associated to a nitric oxide (NO) synthase inhibitor treatment (BLSL and ARSL). Changes in renal perfusion pressure (RPP) were measured in isolated perfused kidneys. BLSL and AR were moderately hypertensive without kidney disease while ARSL developed severe hypertension and renal failure. In the four groups, methacholine induced biphasic endothelium-dependent responses, a transient decrease in RPP followed by a cyclooxygenase-dependent increase in RPP. In the presence or not of indomethacin, the vasodilatations were poorly sensitive to NO synthase inhibition. However, in the presence of cyclooxygenase and NO synthase inhibitors, apamin, and/or TRAM-34, blockers of K_Ca2.3 and K_Ca3.1, respectively, abolished the decrease in RPP in response to either methacholine or the two activators of K_Ca2.3/K_Ca3.1, NS309, and SKA-31. Thus, K_Ca2/3 channels play a major role in the regulation of murine kidney perfusion and this mechanism is maintained in hypertension, even when severe and associated with kidney damage.