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901.
902.
Plasmids of the same Inc groups in Enterobacteria before and after the medical use of antibiotics 总被引:8,自引:0,他引:8
Conjugative plasmids were common in enterobacteria isolated before the medical use of antibiotics. Plasmid F of Escherichia coli K-12 was one example and we identified others in over 20% of a collection of strains isolated between 1917 and 1954, the Murray collection. In the past 25 years, conjugative plasmids encoding antibiotic resistances have become common in bacteria of the same genera as those of the Murray Collection--Salmonella, Shigella, Klebsiella, Proteus, Escherichia. The present study was made to show whether the 'pre-antibiotic' plasmids belonged to the same groups, as defined by incompatibility tests (Inc groups), as modern R plasmids. Of 84 such plasmids established in E. coli K-12, none with antibiotic resistance determinants, 65 belonged to the same groups as present resistance (R) plasmids. Thus the remarkable way in which medically important bacteria have acquired antibiotic resistance in the past 25 years seems to have been by the insertion of new genes into existing plasmids rather than by the spread of previously rare plasmids. 相似文献
903.
Influence of the enteric surface coat on the unidirectional flux of acetamide across the wall of rat small intestine 总被引:1,自引:0,他引:1
In vivo treatment of the jejunal mucosa with glycosidic enzymes seems to remove the enteric surface coat of the enterocyte. As a consequence, the mucosa-to-serosa unidirectional flux of acetamide increases remarkably. The glycocalyx probably represents a barrier to the diffusion of small hydrosoluble solutes. 相似文献
904.
Kurokawa Y. Takahashi M. Hayashi Y. Ohno Y. Takamura N. 《Cellular and molecular life sciences : CMLS》1983,39(12):1404-1407
Cellular and Molecular Life Sciences - Glandular stomachs of fetal and newborn Wistar rats were transplanted s.c. after treatment in vitro with N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) at... 相似文献
905.
906.
Summary Female rats fed 0, 25, 2500 and 10,000 IU vitamin E/kg diet for 3 months were examined for reproductive performance. On 10,000 IU vitamin E/kg diet, the fertility of inseminated rats was significantly reduced as compared to rats given normal or nutritional levels of vitamin E.This work was supported by research grants from the National Research Council of Canada and the Research Committee of The University of British Columbia. We thank Mrs Virginia Green for her help in statistical analysis. Reprint requests should be addressed to Dr I. D. Desai, Professor of Nutrition. 相似文献
907.
N. O. Sjöstrand 《Cellular and molecular life sciences : CMLS》1965,21(2):96-96
Zusammenfassung Der Noradrenalingehalt des Samenleitergewebes von Hahn und Schildkröte ist gleich hoch wie bei Säugetieren. 相似文献
908.
A Guélin I E Michoustina S A Goulevskaya N V Petchnikov L A Ledova 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(21):2171-2174
Marine microvibrios, predators of E. coli, have been detected worldwide, from equatorial waters to the polar regions. The morphology and behavior of two microvibrios have been studied. Their multiplication and aggressiveness in regard to their bacterial prevy are not impeded by dialysis membranes and manifest themselves, away from all direct contact between the predator and its prey. 相似文献
909.
J N Bidard L Cronenberger 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(5):389-392
A new method for the isolation and determination of 3-O-methyldopamine (3 MD) and 4-O-methyldopamine (4 MD) in the urine of Rat has been described. The administration of L-dopa enabled us to detect 4 MD in the urine with a molar ratio 4 MD/3 MD = 0.07. This ratio decreased with the simultaneous treatment of S-adenosylmethionine (SAM). This result might explain the therapeutic L-dopa+SAM in the treatment of parkinsonism, 4 MD being neurotoxic. The low level of 4 MD compared with the level of isovanillic acid, found by other authors, seems to indicate that the 4-O-methylation pathway takes place via dihydroxyphenylacetic acid. 相似文献
910.
N. Thorball 《Cellular and molecular life sciences : CMLS》1982,38(7):876-878
Summary Fluorescein-coupled dextrans (FITC-Ds) were detected in sections in the electron microscope using 4 different contrasting methods when tissue was postfixed in osmium tetroxide. Endogeneous glycogen was also stained by the methods used, but FITC-D particles appeared smaller and more irregular, and in other locations. In dextranase treated specimens glycogen was still visible, while FITC-D was not.Acknowledgments. The author is grateful to Susan Max-Jacobsen, Kjeld Stub and Sonja Fich for excellent technical assistance. The author was supported by a research fellowship from the Danish Medical Research Council (12–1688). 相似文献