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81.
Cloning of chromosomal DNA encoding the F41 adhesin of enterotoxigenic Escherichia coli and genetic homology between adhesins F41 and K88. 总被引:18,自引:2,他引:16 下载免费PDF全文
The genetic determinant for production of the adhesive antigen F41 was isolated from a porcine enterotoxigenic Escherichia coli strain by cosmid cloning. The cloned DNA included sequences homologous to those of hybridization probes prepared from the K88 adhesive antigen operon. Transposon insertions which inactivated F41 production mapped to the same region of DNA showing homology with the K88 genes, demonstrating the genetic relatedness of F41 and K88. Hybridization of a K88 gene probe to plasmid and total DNA from the porcine E. coli isolate from which the F41 gene was cloned indicated that F41 is chromosomally encoded by this strain. This observation was extended to other F41-producing animal isolates. A large number of animal E. coli isolates were examined with K88, F41, and K99 gene probes and for mannose-resistant hemagglutination of human group O erythrocytes and K88 and F41 antigen production. All K88 and F41 antigen producers possessed genetic homology with the K88 and F41 gene probes. Most, but not all, F41-producing strains possessed homology to the K99 gene probe, reflecting the previously observed association of F41 and K99 antigen production. In the strains examined, homology with the K99 gene probe was plasmid associated, whereas homology with the F41 gene probe was chromosomal. The K88 antigen-producing strains showed no homology with the K99 probe. A number of strains possessed homology with the K88 and F41 gene probes and were mannose-resistant hemagglutination positive, but did not produce K88 or F41 antigens. This suggests that there are adhesins among animal isolates of E. coli which are genetically related to but antigenically distinct from K88 and F41. 相似文献
82.
Wolfgang Hagmann Claudio Denzlinger Stephan Rapp Gisbert Weckbecker Dietrich Keppler 《Prostaglandins & other lipid mediators》1986,31(2)
Mercapturic acid formation, an established pathway in the detoxication of xenobiotics, is demonstrated for cysteinyl leukotrienes generated in rats
after endotoxin treatment. The mercapturate N-acetyl-leukotriene E4 (N-acetyl-LTE4) represented a major metabolite eliminated into bile after injection of [3H]LTC4 as shown by cochromatography with synthetic N-acetyl-LTE4 in four different HPLC solvent systems. The identity of endogenoud N-acetyl-LTE4 elicited by endotoxin
was additionally verified by enzymatic deacetylation followed by chemical N-acetylation. The deacetylation was catalyzed by penicillin amidase. Endogenous cysteinyl leukotrienes were quantified by radioimmunoassay after HPLC separation. A N-acetyl-LTE4 concentration of 80 nmol/l was determined in bile collected between 30 and 60 min after endotoxin injection. Under this condition, other cysteinyl leukotrienes detected in bile by radioimmunoassay amounted to less than 5% of N-acetyl-LTE4. The mercapturic acid pathway, leading from the glutathione conjugate LTC4 to N-acetyl-LTE4, thus plays an important role in the deactivation and elimination of these potent endogenous mediators. 相似文献
83.
Cells subjected to the events occurring before, during, and after freezing and thawing are exposed to major changes in the
osmotic pressure of the surrounding medium; i.e., the osmolalities can exceed 30. An important question in understanding the
mechanisms of injury is whether cells respond as ideal osmometers to these strongly anisotonic solutions. Mouse and bovine
embryos from eight-cell to blastocyst stage were used to investigate the question. They were found to behave as ideal osmometers
at room temperature over a wide range of tonicities; i.e., from four times isotonic to almost 1/3 times isotonic, ideality
being defined by a Boyle-van't Hoff equation. Embryo volumes increased from 40 to 200% of isotonic over this range and survivals
of mouse embryos were unaffected. However, outside this range the membrane apparently becomes leaky and the survival of mouse
embryos drops sharply. Osmolalities rise to high values during freezing and the paper develops the thermodynamic equations
to show how computed cell volumes as a function of subzero temperature can be translated into the Boyle-van't Hoff format
of cell volume as a function of the reciprocal of osmolality. 相似文献
84.
"Suspicious" gynecologic smears from 842 patients over a seven-year period were analyzed for their causes and outcomes. The frequency of the cytologic diagnosis of "suspicious" ranged between 0.5% in 1979 and 1.44% in 1975 of all smears examined. Review of the smears showed that this classification was used to report a variety of conditions, including equivocal possible precancerous changes as well as the presence of severe inflammation, degenerative or atrophic changes, abnormal glandular cells and metaplasia. The cytologic follow-up, following anti-inflammatory or hormonal therapy, showed a conversion to negative findings in 65.1% of all cases, usually within 12 months. In 294 cases, histologic analysis became necessary, revealing precancerous changes or cancer in 147 patients (17.5% of the study group). Smears of postmenopausal women with suspicious glandular or endometrial cells received special analysis. Significant numbers of such cases had histologic findings positive for malignancy (20% of smears with glandular cells and 21.3% with endometrial cells), as did also smears showing post-irradiative changes (34.6%) or atrophic and degenerative changes (17.1%). Therefore, "suspicious" smears in these groups were considered to indicate an increased risk of malignancy. A regimen for the proper management of cases with "suspicious" smears has been established. 相似文献
85.
12 beta-dehydrogenation of bile acids by Clostridium paraputrificum, C. tertium, and C. difficile and epimerization at carbon-12 of deoxycholic acid by cocultivation with 12 alpha-dehydrogenating Eubacterium lentum. 总被引:1,自引:1,他引:0 下载免费PDF全文
12 beta-Hydroxysteroid dehydrogenating activities were detected in 13 strains of Clostridium paraputrificum, 1 strain of C. tertium, and 1 strain of C. difficile, together with a 3 alpha- and 3 beta-hydroxysteroid dehydrogenase system in many strains. Redox reactions a C-12 of disubstituted and trisubstituted bile acids were performed unspecifically by representative strains of C. paraputrificum. 3 alpha,12 beta-, 3 beta,12 beta-Dihydroxy-, 3 alpha, 7 alpha, 12 beta-trihydroxy-, and 3-keto,12 beta-hydroxy-5 beta-cholanoic acids, so far not known as bacterial bile acid metabolites, were identified. Epimerization of the 12 alpha-hydroxyl group of deoxycholate via the 12-keto intermediate was achieved by cocultivation of C. paraputrificum and Eubacterium lentum, elaborating a 12 alpha-hydroxysteroid dehydrogenase only. In addition, epimerization at C-12 was demonstrated with mixed human fecal cultures. 相似文献
86.
S Matano G Baron H Stephan H D Frahm 《Folia primatologica; international journal of primatology》1985,44(3-4):182-203
Volumes of medial, interposed, and lateral cerebellar nuclei (MCN, ICN, and LCN) were measured in Insectivora, Scandentia, and Primates, including man. The relative size of the nuclei was expressed in size indices. Insectivora had by far the smallest cerebellar nuclei. The simians, in general, had larger cerebellar nuclei than the prosimians, but there was considerable overlap. From Insectivora to man, the MCN was the least progressive and the LCN the most progressive. The indices are expected to reflect the relative size of the three longitudinal zones of the cerebellum (vermis/MCN, pars intermedius/ICN, hemisphere/LCN). They, together with those of the ventral pons and cerebellum (part I), are discussed in relation to the predominant locomotor pattern of a species, and with reference to evolutionary trends in primate phylogeny. 相似文献
87.
A mos oncogene-containing retrovirus, myeloproliferative sarcoma virus, transforms rat thyroid epithelial cells and irreversibly blocks their differentiation pattern. 总被引:8,自引:1,他引:7 下载免费PDF全文
A Fusco G Portella P P Di Fiore M T Berlingieri R Di Lauro A B Schneider G Vecchio 《Journal of virology》1985,56(1):284-292
88.
By use of the pressure-clamp technique, the hydraulic conductivity of the brackish-water alga Lamprothamnium was found to be 5·10-6 cm s-1 bar-1. The dimensions of the internodes are so small that it is possible, for the first time, to measure a complete volume relaxation upon clamping the turgor pressure to a preset value by a feedback control of the pressure probe. As theoretically predicted, the values of the hydraulic conductivity obtained from the initial slope of the volume relaxation induced by the pressure clamp are in agreement (within experimental error) with those obtained from the half-time of the relaxation process. The cell volume also obtained from the analysis of the volume relaxation is the osmotically effective cell volume and is therefore slightly smaller than the value obtained by taking the dimensions of the cell including the cell wall.Abbreviations and symbols Lp
hydraulic conductivity
- P
turgor pressure
- Sv
initial slope of volume relaxion
- T1/2
half-time of volume relaxation
Dedicated to Professor Dr. H. Ziegler on the occasion of his 60th birthday 相似文献
89.
12 beta-Hydroxysteroid dehydrogenating activities were detected in 13 strains of Clostridium paraputrificum, 1 strain of C. tertium, and 1 strain of C. difficile, together with a 3 alpha- and 3 beta-hydroxysteroid dehydrogenase system in many strains. Redox reactions a C-12 of disubstituted and trisubstituted bile acids were performed unspecifically by representative strains of C. paraputrificum. 3 alpha,12 beta-, 3 beta,12 beta-Dihydroxy-, 3 alpha, 7 alpha, 12 beta-trihydroxy-, and 3-keto,12 beta-hydroxy-5 beta-cholanoic acids, so far not known as bacterial bile acid metabolites, were identified. Epimerization of the 12 alpha-hydroxyl group of deoxycholate via the 12-keto intermediate was achieved by cocultivation of C. paraputrificum and Eubacterium lentum, elaborating a 12 alpha-hydroxysteroid dehydrogenase only. In addition, epimerization at C-12 was demonstrated with mixed human fecal cultures. 相似文献
90.
Henry Schneider George Mahmourides John L. Labelle Hung Lee Nancy Maki Heather J. McNeill 《Biotechnology letters》1985,7(5):361-364
The formation of ethanol, xylitol, ribitol, arabitol and acetic acid from D-xylose byPachysolen
tannophilus correlated with the limitation of growth. The correlation was consistent with these products being secondary metabolites.Issued as NRCC Publication Number 24259. 相似文献