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Virion conformational forms and the complex inactivation kinetics of echovirus by chlorine in water 总被引:1,自引:0,他引:1
Aberrant inactivation kinetics were observed when monodispersed echovirus type 1 (Farouk) was inactivated with chlorine. An initial 1- to 2-log10-unit decrease in titer was followed by lag period, during which the titer stayed the same or increased, and this was followed by a final decline in titer. First-order kinetics were obtained with poliovirus type 1 under the same conditions. Isoelectric focusing studies of echovirus before chlorine treatment showed that the virus distributed into two pH-dependent and interconvertible isoelectric forms. After chlorine treatment all remaining virus infectivity was associated with a third pH-independent isoelectric form. The complex inactivation kinetics appeared to be due to shifts between these conformational forms during inactivation in certain ionic environments. Under certain conditions the conformational shifts resulted in substantial resistance of monodispersed echovirus to chlorine. 相似文献
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Mixed agonist/antagonist properties of NAN-190 at 5-HT1A receptors: behavioural and in vivo brain microdialysis studies 总被引:2,自引:0,他引:2
1-(2-Methoxyphenyl)-4-[4-(2-phthalimido)butyl]piperazine, NAN-190, is a novel compound with putative 5-HT1A antagonist properties. In the present study, the effects of NAN-190 were examined with regard to functional pre- and post-synaptic 5-HT1A receptor-mediated events, using in vivo brain microdialysis and behavioural techniques. Our findings provide evidence that NAN-190 acts as a mixed agonist/antagonist at central 5-HT1A receptors. Thus, NAN-190 blocked (+)8-OH-DPAT-induced behaviour in reserpinized rats, indicating antagonist properties at postsynaptic 5-HT1A receptors. However, the compound was also able to decrease the release of 5-HT in vivo, tentatively due to an agonist action at somatodendritic 5-HT1A autoreceptors. These data extend previous information on the pharmacological profile of NAN-190 and further emphasizes the difference between pre- and postsynaptic 5-HT1A receptors in brain. 相似文献
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The isolation and characterization of bacteriophages infecting obligately thermophilic strains of Bacillus 总被引:2,自引:0,他引:2
R J Sharp S I Ahmad A Munster B Dowsett T Atkinson 《Journal of general microbiology》1986,132(6):1709-1722
Twenty-four thermophilic bacteriophages have been isolated from diverse sources such as compost, soil, silage and rotting straw. Although considerable individual host specificity was observed, the phages were able to infect most of the major taxonomic groups of Bacillus thermophiles. The phages varied considerably in morphology and size; the phage heads were either cylindrical or polyhedral with tails varying in length between 15 and 500 nm. Most of the phages were stable at 50 degrees C for 4-5 h but at 70 degrees C the plaque-forming units decreased by between 10(2)- and 10(7)-fold in 2 h. The DNA of morphologically similar phages was examined by restriction enzyme analysis, and some differences in the DNA fragment patterns were found. Efficiency of plating data indicated that 'B. caldotenax' has a restriction and modification system. These phages may be valuable for the study of the genetics of thermophilic bacilli: transduction of 'B. caldotenax' and 'B. caldovelox' by phage JS017 has been observed. 相似文献
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Summary Bicarbonate-stimulated Mg2+ dependent ATPase activity was demonstrated both biochemically and cytochemically, in brush border membranes from rat, rabbit and guinea pig duodenum. There was no correlation between enzyme activity and basal HCO
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secretion rates in the different species. The concentration of HCO
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necessary for optimal stimulation of ATPase activity, degree of stimulation and total activity was higher in the rat than in other species. Activity was higher in rat duodenum than in the ileum. This is consistent with the proposed electrogenic HCO
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secretion in the duodenum. Distribution of activities of alkaline phosphatase and HCO
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-stimulated Mg2+-ATPase along the duodenal villus showed significant differences, suggesting that the two activities reflect, at least in part, distinct enzymes. 相似文献
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Prostaglandin dehydrogenase activity of purified rat liver 3 alpha-hydroxysteroid dehydrogenase 总被引:1,自引:0,他引:1
Homogeneous 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) from rat liver cytosol displays 9, 11, and 15-hydroxyprostaglandin dehydrogenase activity. Using [14C]-PGF2 alpha as substrate the products of this reaction were separated by TLC and identified by autoradiography as PGE2 and PGB2. The purified enzyme catalyzes this reaction at a rate 200 times faster than cytosol. This corresponds to the rate enhancement observed when the enzyme is purified from cytosol using androsterone (a 3 alpha-hydroxysteroid) as substrate and suggests that it may represent a major 9-hydroxyprostaglandin dehydrogenase in this tissue. Although the 3 alpha-HSD has many properties in common with the 9-hydroxyprostaglandin dehydrogenase of rat kidney, rat kidney contains no protein that is immunodetectable with polyclonal antibody raised against the purified 3 alpha-HSD. 相似文献