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1.
S. Bereswill F. Fassbinder C. Völzing A. Covacci R. Haas M. Kist 《Medical microbiology and immunology》1998,186(4):177-187
Various strains of Helicobacter pylori were able to lyse erythrocytes from sheep, horse, and human when grown on blood agar. The hemolysis did not depend on the
production of the vacuolating cytotoxin VacA as demonstrated by the hemolytic behavior of an isogenic vacA-negative mutant strain. The hemolytic activity could be detected in cell-free supernatants and was not regulated by iron.
To isolate genes coding for proteins involved in the destruction of erythrocytes, a plasmid-based DNA library was screened
for expression of lytic activity on blood agar. This approach revealed that the H. pylori ribA gene confers hemolytic properties to Escherichia coli. The ribA gene encodes the enzyme GTP-cyclohydrolase II [EC 3.5.4.25] that catalyzes the initial step in the synthesis of riboflavin.
The predicted amino acid sequence of the H. pylori RibA protein showed a high degree of similarity to equivalent enzymes from microorganisms and from plants. The single gene
on a plasmid restored riboflavin synthesis in a ribA mutant of E. coli and induced hemolytic activity. Furthermore, ribA overexpression was associated with the production of a fluorescent yellow molecule that was not identical with riboflavin.
Hemolysis was also seen for the ribA gene from E. coli, indicating that this feature was not specific for the H. pylori gene. The presence of ribA in various H. pylori strains was confirmed by Southern blot hybridization and by polymerase chain reaction with specific primers. This analysis
revealed that microdiversity exists within the DNA region upstream from ribA, which was further confirmed by nucleotide sequence analysis.
Received: 25 July 1997 相似文献
2.
本实验发现大鼠体表面积20%Ⅲ°烧伤后,皮肤内产生了大量丙二醛(MDA),第二天达最高,第七天有第二高峰,血浆和红细胞(RBC)MDA第三天达最高,血浆和RBC维生素E(VE)于伤后第二天后迅速下降,RBC溶血第三天最甚。对皮肤MDA、血浆MDA、RBCMDA、血浆VE、BBC VE、1%H_2O_2溶血进行相关分析后发现在不同时相,有不同的相关关系,但基本遵循烧伤皮肤MDA增加、血浆MDA增加、RBC MDA增加、血浆和RBC VE降低,溶血增加的规律。文中讨论了RBC损伤的机制。 相似文献
3.
珊瑚涂层人工骨的制备及溶血实验研究 总被引:2,自引:0,他引:2
目的根据生物工程及化工等原理,制备珊瑚人工骨,并检测此珊瑚(Coral)复合人工骨的血液相容性。方法将制备的珊瑚复合人工骨、按照国际标准化组织和我国国家标准规定要求,采用将珊瑚复合人工骨及其浸提液与抗凝稀释兔血直接接触,测定红细胞释放的血红蛋白量(OD值),将测得的OD值换算为溶血率。结果珊瑚复合人工骨材料浸提液组的溶血率为1.81%,材料与血液直接接触组溶血率为1.41%,阴性对照组和阳性对照组溶血率分别为0%、100%。结论珊瑚复合人工骨材料无溶血作用,血液相容性良好。 相似文献
4.
为了探讨血小板计数在血泵离体实验中的意义。我们用两种滚压泵分成两组,作5对16小时离体长时间转流实验,血样本为转前作对照组、转流4h后每隔2h抽1次。测定项目:血小板计数、游离血红蛋白。结果:两组血小板计数值均随转流时间延长而呈线性逐渐增加,各时点值与前时点比(P<0.05),有显著差异,两组游离血红蛋白量也随转流时间延长而呈线性增加。血小板计数与游离血红蛋白呈直线回归相关关系。结论;在血泵离体转流实验中,血小板计数可反映血细胞碎片的数量,因此可作为一项评价血泵离体溶血性能的客观指标。 相似文献
5.
A microcapsule suspension, a substitute for animal blood in hemolysis tests, has been developed for evaluation of the absolute hemolytic properties of circulatory artificial organs. The microcapsule suspension was made by dispersing microcapsule slurry into an ethylene glycol sodium chloride solution. The microcapsule slurry was composed of a leuco dye solution and polyurethane membrane made by the reaction between aliphatic poly-isocyanate and polyamine by interfacial polycondensation. The microcapsule was a small particle containing dye inside. The microcapsule suspension was white; the diameter of the microcapsules was from 5 to 100 microns. The specific gravity of the suspension was 1.024, and the membrane was elastic. The fluid showed Newtonian characteristics, different from animal blood, and its viscosity was approximately 5.8 mPa.s. After the microcapsules were destroyed, the leuco dye was extracted with n-hexane from the suspension and was measured by spectroscopy after being colored with acid ethanol. Hemolysis can be regarded as a fatigue fracture of cell membranes rather than a static fracture. The destruction of microcapsules by a Potter type tissue grinder was observed at a low stroke number region and was compared to rat blood. Moreover, hemolysis tests of a commercially available centrifugal blood pump and the prototype of our centrifugal pump for mechanism checks were carried out with bovine blood. The hemolysis level of the prototype pump increased with time while the hemolysis level of the commercial blood pump did not change as much as that of the control when both pumps were tested with the microcapsule suspension. These results are similar to tests utilizing bovine blood. Therefore, hemolysis tests of circulatory artificial organs completed with microcapsule suspension are expected to provide results similar to tests with animal blood. 相似文献
6.
A computational fluid dynamics study of blood flow in the continuous flow ventricular assist device, Prototype No. 3 (CFVAD3), which consists of a 4 blade shrouded impeller fully supported in magnetic bearings, was performed. This study focused on the regions within the pump where return flow occurs to the pump inlet, and where potentially damaging shear stresses and flow stagnation might occur: the impeller blade passages and the narrow gap clearance regions between the impeller-rotor and pump housing. Two separate geometry models define the spacing between the pump housing and the impeller's hub and shroud, and a third geometry model defines the pump's impeller and curved blades. The flow fields in these regions were calculated for various operating conditions of the pump. Pump performance curves were calculated, which compare well with experimentally obtained data. For all pump operating conditions, the flow rates within the gap regions were predicted to be toward the inlet of the pump, thus recirculating a portion of the impeller flow. Two smaller gap clearance regions were numerically examined to reduce the recirculation and to improve pump efficiency. The computational and geometry models will be used in future studies of a smaller pump to determine increased pump efficiency and the risk of hemolysis due to shear stress, and to insure the washing of blood through the clearance regions to prevent thrombosis. 相似文献
7.
The venom of the Neotropical social wasp Protopolybia exigua(Saussure) was fractionated by RP-HPLC resulting in the elution of 20 fractions. The homogeneity of the preparations were checked out by using ESI-MS analysis and the fractions 15, 17 and 19 (eluted at the most hydrophobic conditions) were enough pure to be sequenced by Edman degradation chemistry, resulting in the following sequences: Protopolybia MPI I-N-W-L-K-L-G-K-K-V-S-A-I-L-NH2 Protopolybia-MP II I-N-W-K-A-I-I-E-A-A-K-Q-A-L-NH2 Protopolybia-MP III I-N-W-L-K-L-G-K-A-V-I-D-A-L-NH2 All the peptides were manually synthesized on-solid phase and functionally characterized. Protopolybia-MP I is a hemolytic mastoparan, probably acting on mast cells by assembling in plasma membrane, resulting in pore formation; meanwhile, the peptides Protopolybia-MP II and -MP III were characterized as a non-hemolytic mast cell degranulator toxins, which apparently act by virtue of their binding to G-protein receptor, activating the mast cell degranulation. 相似文献
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10.
目的:通过对两种不同采血标本法的比较,探讨采血标本时不取下针头将血液缓慢注入干试管会不会导致溶血,方法:采用随机配对的方法将受试者分为实验组和对照组,在其它条件相同的情况下,实验组抽血后不取下针头,对照组抽血后取下针头将血缓慢沿试管壁注入干试管内观察两组血清钾离子均值有无差异性,结果:两种不同采血标本法采得血液所测得血清钾离子均值差异无显著意义(P>0.05),用实验组方法采血标本不会导致溶血,结论:采血标本时,不取下针头将血缓慢沿试管壁注入干试管内不会导致溶血,并可以减轻护士因职业暴露而感染经血液传播疾病的危险。 相似文献