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141.
Coli-aerogenes Bacteria on Plants   总被引:2,自引:0,他引:2  
S ummary . Specimens of plant foliage and flowers collected in the region of Attica from various situations and geographical regions were examined over a period of 13 months for the presence of coli-aerogenes bacteria able to grow at 37°. Twenty-five (12.2%) of 204 specimens carried coli-aerogenes bacteria of which Escherichia coli type I was isolated from 12 (5.8%). Coli-aerogenes bacteria were seldom isolated from plants grown in uninhabited areas, and they occured more frequently during summer and autumn.
Vegetables and fruits sold in the central market of Athens are frequently contaminated with coli-aerogenes bacteria. Of 76 specimens of vegetables examined 66 (86.8%) were positive for coli-aerogenes bacteria, and 17 (22.3%) for E. coli type I. The figures from 41 specimens of fruits were 26 (65.8%) and 4 (9.7%), respectively.  相似文献   
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The amount of 3Fe clusters in Thermodesulfobacterium commune ferredoxin is strongly dependent upon the presence of oxygen during the purification. An average of one 3Fe cluster per monomer can be found when the purification is not strictly anaerobic. These clusters are converted into |4Fe-4S| clusters by adding dithionite at usual pH and without adjunction of Fe2+. The EPR potentiometric titration reveals the existence of several types of 3Fe clusters with negative midpoint potentials differing by more than 100 mV. When the |4Fe-4S| clusters are partially reduced the EPR signal is composed of two different rhombic components. The component with gz = 2.04 could be related to a site implicated in the interconversion processes. In the fully reduced state, the spectrum presents the typical features of two interacting |4Fe-4S| clusters as those observed in two |4Fe-4S| bacterial ferredoxins. From the redox titration curves the midpoint potentials of these clusters are estimated at −395 and −435 mV.  相似文献   
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Insulin resistance, the failure to respond to normal circulating concentrations of insulin, is a common state associated with obesity, aging, and a sedentary lifestyle. Compelling evidence implicates TNFalpha as the cause and link between obesity and insulin resistance. Serine phosphorylation of insulin receptor substrate-1 seems prominent among the mechanisms of TNFalpha-induced insulin resistance. Recent advances indicate that serine kinases may phosphorylate and thus inhibit the tyrosine phosphorylation of insulin receptor substrate-1, revealing an integration point of TNFalpha and insulin signaling pathways. Selective targeting of the molecular scenery whereby this key phosphorylation occurs/operates represents a rich area for the development of rationally designed new antidiabetic drugs. In relation to efficacy and side effects, this prospect should permit a more precise and perhaps individualized approach to therapeutic intervention, allowing clinicians to focus the attack where the problem lies.  相似文献   
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Epigenetic changes, or heritable alterations in gene function that do not affect DNA sequence, are rapidly gaining acceptance as co-conspirators in carcinogenesis. Although DNA methylation signature analysis by methylation-specific polymerase chain reaction has been a breakthrough method in speed and sensitivity for gene methylation studies, several factors still limit its application as a routine diagnostic and prognostic test.  相似文献   
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Clinical isolates of Escherichia coli sensitive and resistant to penicillin were compared in lipid composition and 14C-labelled penicillin uptake, as possible factors in resistance. Except for a slight increase in the triglyceride fraction in sensitive strains there were no qualitative or quantitative differences in the classes of extractable lipids present. Gas-liquid chromatography of the phospholipid and triglyceride fatty acids of the polar and non-polar fatty acids of the bound lipids showed that the same kinds of fatty acids were present. There was an increase of myristate in the chloroform-methanol extractable lipids of highly resistant strains accompanied by a rather general decrease of other fatty acids. Gas-chromatographic analysis of the polar-bound lipids showed an increase of the beta-hydroxydecanoic acid in the resistant strains. By studying the uptake of 14C-labelled benzylpenicillin and the crypticity of the beta-lactamase, evidence has been produced that a decreased permeability of resistant strains to penicillin cooperates with beta-lactamase to induce a high level of resistance. The altered lipid metabolism may reflect the special architectural changes in the cell wall which cause decreased permeability.  相似文献   
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