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排序方式: 共有2080条查询结果,搜索用时 15 毫秒
221.
J Frank DK Kelleher A Pompella O Thews HK Biesalski P Vaupel 《Canadian Metallurgical Quarterly》1998,58(13):2693-2698
Polymerase chain reaction (PCR) assays were designed to amplify 56- and 99-base regions of the pmoA gene from Methylosinus trichosporium OB3b and Methylomicrobium albus BG8, two species of methanotrophic bacteria that are of interest for monitoring bioremediation activity. The PCR product sizes are in a mass range that is accessible to analysis by MALDI-TOF mass spectrometry. A rapid purification procedure using commercially available reversed-phase cartridges was applied prior to MALDI-TOF analysis. A small aliquot (1.5%, 1.5 microL) from a single 100-microL PCR reaction was sufficient for reliable detection. No cross-amplification products were observed when primers designed for one bacterial species were used with genomic DNA of the other species. The methodology described here has potential to allow less expensive and faster characterization of the ability of microbial populations to destroy pollutants in groundwater and soil at contaminated industrial sites. 相似文献
222.
An 8-day-old newborn presented with non-bilious vomiting, upper abdominal fullness, and failure to pass meconium. Plain radiographs revealed gastric pneumatosis (GP). At operation, he was found to have a non-obstructive preduodenal portal vein, preampullary duodenal atresia, asplenia, and malrotation. The baby was treated by duodeno-duodenostomy without mobilizing the portal vein and correction of the malrotation according to Ladd's procedure. He made an uneventful recovery and the GP resolved spontaneously. The malformative process was believed to have occurred at or soon after the 5th week of gestation, and the GP probably resulted from intramural air tracking through mucosal tears caused by high intragastric pressure. 相似文献
223.
The BCMA gene is a new gene discovered by the molecular analysis of a t(4;16) translocation, characteristic of a human T cell lymphoma. It has no significant similarity with any known protein or motif, so that its function was unknown. This report describes the cloning of murine BCMA cDNA and its genomic counterpart. The mouse gene is organized into three exons, like the human gene, and lies in murine chromosome 16, in the 16B3 band, the counterpart of the human chromosome 16p13 band, where the human gene lies. Murine BCMA cDNA encodes a 185 amino acids protein (184 residues for the human), has a potential central transmembrane segment like the human protein and is 62% identical to it. The murine BCMA mRNA is found mainly in lymphoid tissues, as is human BCMA mRNA. Alignment of the murine and human BCMA protein sequences revealed a conserved motif of six cysteines in the N-terminal part, which strongly suggests that the BCMA protein belongs to the tumor necrosis factor receptor (TNFR) superfamily. Human BCMA is the first member of the TNFR family to be implicated in a chromosomal translocation. 相似文献
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SC Stevenson M Rollence B White L Weaver A McClelland 《Canadian Metallurgical Quarterly》1995,69(5):2850-2857
The adenovirus fiber protein is responsible for attachment of the virion to cell surface receptors. The identity of the cellular receptor which mediates binding is unknown, although there is evidence suggesting that two distinct adenovirus receptors interact with the group C (adenovirus type 5 [Ad5]) and the group B (Ad3) adenoviruses. In order to define the determinants of adenovirus receptor specificity, we have carried out a series of competition binding experiments using recombinant native fiber polypeptides from Ad5 and Ad3 and chimeric fiber proteins in which the head domains of Ad5 and Ad3 were exchanged. Specific binding of fiber to HeLa cell receptors was assessed with radiolabeled protein synthesized in vitro, and by competition analysis with baculovirus-expressed fiber protein. Fiber produced in vitro was found as both monomer and trimer, but only the assembled trimers had receptor binding activity. Competition data support the conclusion that Ad5 and Ad3 interact with different cellular receptors. The Ad5 receptor distribution on several cell lines was assessed with a fiber binding flow cytometric assay. HeLa cells were found to express high levels of receptor, while CHO and human diploid fibroblasts did not. A chimeric fiber containing the Ad5 fiber head domain blocked the binding of Ad5 fiber but not Ad3 fiber. Similarly, a chimeric fiber containing the Ad3 fiber head blocked the binding of labeled Ad3 fiber but not Ad5 fiber. In addition, the isolated Ad3 fiber head domain competed effectively with labeled Ad3 fiber for binding to HeLa cell receptors. These results demonstrate that the determinants of receptor binding are located in the head domain of the fiber and that the isolated head domain is capable of trimerization and binding to cellular receptors. Our results also show that it is possible to change the receptor specificity of the fiber protein by manipulation of sequences contained in the head domain. Modification or replacement of the fiber head domain with novel ligands may permit adenovirus vectors with new receptor specificities which could be useful for targeted gene delivery in vivo to be engineered. 相似文献
227.
Random night blood samples were examined from 528 subjects in an endemic zone of lymphatic filariasis, in the coastal region of West Bengal. There were 136 cases out of 528 who were symptomatic, with or without recurrent episodes of fever, lymphangitis and lymphadenitis and with various degrees of lymphoedema. Examination of blood samples revealed microfilaria in 43 cases of which 42 were asymptomatic and only one was symptomatic with lymphoedema. All the microfilariae were of the species Brugia malayi. 相似文献
228.
NADPH diaphorase (NADPH-d) histochemistry is a useful technique for examining select neuronal populations in both experimental studies and human neuropathology and also provides a simple method to localize nitric oxide synthase in the central nervous system. However, no established method exists for detecting quantitative changes of NADPH-d histochemistry under different experimental conditions. To develop a quantitative procedure, we systematically examined the properties of NADPH-d histochemistry and then investigated the correlation between the number of NADPH-d positive cells and the optical density of NADPH-d histochemistry in the rat striatum. NADPH-d activity was sensitive to specific experimental conditions, such as incubation time, fixation, and high temperature. In the striatum NADPH-d activity of neuropil was more sensitive to these conditions than were the somata. The different staining patterns of NADPH-d between the neuropil of the striatum and white matter, such as the optic tract suggest neuropil staining in the striatum is not just unspecific background staining. Increasing incubation time only increased the optical density of NADPH-d staining, in contrast, the number of NADPH-d positive cells counted was relatively consistent across incubation times. Therefore, little correlation existed between the optical density and cell number. These results indicate that when using NADPH-d histochemistry, the number of NADPH-d positive neurons is independent of the optical density of the staining, and these two parameters should be considered and treated separately when conducting quantitative analysis related to an experimental treatment. 相似文献
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Karen L Cropsey Gloria D Eldridge Michael F Weaver Gabriela C Villalobos Maxine L Stitzer 《Nicotine & tobacco research》2006,8(5):653-659
Breath carbon monoxide (CO) is a convenient, widely used method for abstinence validation, with cutoffs of 8-10 ppm commonly employed. The goal of the present study was to determine an appropriate CO cutoff to differentiate nonsmokers and smokers within a large sample (N = 374) of female prisoners incarcerated at a correctional facility in Virginia. Mean age of the population was 34.5 years, 49.2% were White, and 29% had less than a high school education. Smoking prevalence was 74.1% within the prison population. Examination of CO levels versus smoking self-report using a receiver operator characteristic (ROC) analysis revealed that a CO cutoff of 3 ppm resulted in the best sensitivity (98.1%) and specificity (95.8%). Overall ROC area under the curve was 99% (95% CI = 98.2%-99.9%). This same cutoff was optimal for smoking subgroups including Black and light (<10 cigarettes/day) smokers. Results suggest that CO cutoffs higher than 3 ppm may misclassify some smokers as nonsmokers and underestimate the prevalence of smoking. 相似文献