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91.
92.
The effects of D- and L-isoprenaline on systemic vascular adrenoceptors of the cod was studied using blood pressure recording from conscious cod in vivo and isolated coeliac artery strip preparations in vitro. Experiments with isolated artery preparations demonstrated that the D-, but not the L-isomer of isoprenaline acts as an alpha-adrenoceptor antagonist. A dose-dependent reduction of ventral and dorsal aortic blood pressures together with a dose-dependent increase in the heart rate could be produced by injection of L-isoprenaline. D-Isoprenaline, on the other hand, had no effect on the blood pressures or heart rate except in the highest dose injected. The results show an alpha-adrenoceptor blocking capacity of D-isoprenaline in the cod. The effect of L-isoprenaline on the blood pressure supports the idea that the hypotensive effect of DL-isoprenaline seen in previous studies of the cod may be attributed to an effect of the L-isomer on beta-adrenoceptors mediating vasodilation of the cod systemic vasculature. 相似文献
93.
Expression of the gene encoding protein A in Staphylococcus aureus and coagulase-negative staphylococci 总被引:13,自引:4,他引:9 下载免费PDF全文
Two shuttle vectors containing the gene for protein A (spa) from Staphylococcus aureus have been constructed to study expression of the gene in various strains of S. aureus and in the coagulase-negative species Staphylococcus epidermidis, Staphylococcus capitis, and Staphylococcus xylosus. One plasmid, pSPA15, contains the complete structural gene for protein A, which binds to the cell wall in various Staphylococcus species. The other plasmid, pSPA16, codes for a truncated protein A lacking the C-terminal part called region X. The latter is exclusively extracellular in all Staphylococcus species tested, which confirms the importance of region X for cell wall binding. The expression of the plasmid-coded protein A in various strains of S. aureus is strongly correlated to the expression of the chromosomal spa gene. The coagulase-negative species expressing plasmid-encoded protein A produce 12 to 30% of the amount coded by the chromosomal spa gene in S. aureus strains Cowan I and A676. 相似文献
94.
Cultured adult cardiac myocytes were exposed to anoxia under substrate-free conditions. When compared to the metabolic changes in the oxygen deficient organ, those in the anoxic cell culture proceed in a similar, yet prolonged manner. Release of cytosolic enzymes starts with minor energetic disturbances and proceeds in close correlation to the actual ATP decay. Below 2 μmol. ATP/gWW, an increasing number of cells becomes irreversibly damaged, but above, 30 min reoxygenation leads to extensive recovery of the whole preparation. The results indicate that leakage of cytosolic enzymes during the early stage of anoxia is due to a gradual protein release from the individual cells, related to reversible membrane alterations. 相似文献
95.
Irma van Die Ingrid van Megen Wiel Hoekstra Hans Bergmans 《Molecular & general genetics : MGG》1984,194(3):528-533
Summary The genes responsible for the formation of the F72 fimbriae of the uropathogenic E. coli strain AD110 (O6:K2:H1:F7) have been cloned on the recombinant plasmid pPIL110-35 (Van Die et al. 1983). The F72 fimbriae, like the F71 fimbriae of AD110, are responsible for mannose resistant haemagglutination (MRHA).The molecular organisation of the genes of pPIL110-35 involved in the expression of MRHA was studied by: (a) analysis of transposon and Tn5 insertion mutants. Mutations that cause an MRHA-deficient phenotype were located in discrete groups within an 11.5 kb restriction fragment of pPIL110-35, separated by insertion mutations that do not inactivate MRHA. (b) complementation experiments. Restriction fragments of pPIL110-35 subcloned in the vector pBR322 were tested for their ability to complement transposon insertion mutations in the corresponding regions of pPIL110-35. Five complementation groups were distinguished.Five genes (designated A-E) involved in the expression of MRHA can be distinguished by these results. The products of these genes were analysed in minicells. The results indicate that gene B codes for a 75 K dalton protein, gene C for a 23 K dalton protein and gene E for a 36 K dalton protein. No product of gene D was observed. Gene A probably codes for the 17 K dalton subunit polypeptide of the F72 fimbriae, as will be discussed. 相似文献
96.
Indole-3-methanol is a product of indole-3-acetic acid metabolism in wheat leaves ( Triticum compactum Host., cv. Little Club). It leads either to the production of the corresponding aldehyde and carboxylic acid, to the production of a polar glucoside which releases indole-3-methanol on β-glucosidase treatment, or to an unidentified apolar product on mild alkaline hydrolysis in aqueous methanol. With reference to a published pathway of indole-3-acetic acid degradation, the results provide evidence for a prominent role of indole-3-methanol and also for the occurrence of co-oxidation processes in wheat leaves involving indole-3-acetic acid and phenolic cosubstrates. 相似文献
97.
Growth factors induce early pre-replicative changes in senescent human fibroblasts. 总被引:5,自引:0,他引:5 下载免费PDF全文
Y Paulsson M Bywater S Pfeifer-Ohlsson R Ohlsson S Nilsson C H Heldin B Westermark C Betsholtz 《The EMBO journal》1986,5(9):2157-2162
As human fibroblasts in culture senesce their response to platelet-derived growth factor (PDGF) becomes attenuated. To clarify at which level such cells are blocked in the pre-replicative part of the cell cycle, we have analysed PDGF-induced pre-replicative events in senescent (phase III) cultures. We found that phase III cells retain a normal number of PDGF receptors and that these are functional with regard to PDGF-induced receptor autophosphorylation. Phase III cells also respond to PDGF by rapid actin reorganization and increased levels of c-fos and c-myc mRNA, similar to growth-arrested phase II fibroblasts. However, the expression of the nuclear antigen K-67, which in phase II cell is induced in S-phase and continues to be expressed throughout the cell cycle, is not induced in phase III cells in response to PDGF. We conclude that phase III human fibroblasts, although blocked with regard to proliferation, still retain a functional growth factor receptor system, and display early responses when exposed to growth factors, such as changes in the cytoskeleton and the expression of proto-oncogenes. 相似文献
98.
4-Trifluoroacetamidoaniline was reacted with reducing oligosaccharides in the presence of sodium cyanoborohydride to give aminoalditol derivatives, useful for linkage to proteins or solid matrices. A mixture of reducing oligosaccharides, difficult to separate by HPLC, was treated in the same way. The resulting derivatives were easily separated by HPLC.Abbreviations TFAN
4-trifluoroacetamidoaniline
- LcOse4
lacto-N-tetraose
- IV2Fuc-LcOse4
lacto-N-fucopentaose l
- III4Fuc-LcOse4
lacto-N-fucopentaose II
- III3Fuc-nLcOse4
lacto-N-fucopentaose III
- IV2Fuc, III4Fuc-LcOse4
lacto-N-difucohexaose I
- II6Galß1-4GlcNAc-LcOse4
lacto-N-hexaose
- II3NeuAc-Lac
3-sialyllactose
- GlcNAcß1-4GlcNAcß1-4GlcNAc
chitotriose
- GalNac1-3|Fuc1-2|Galß1-4Glc
A-tetrasaccharide 相似文献
99.
Chromatophores isolated from the marine phototrophic bacterium Rhodobacter sulfidophilus were found to photoreduce NAD with sulfide as the electron donor. The apparent K
m for sulfide was 370 M and the optimal pH was 7.0. The rate of NAD photoreduction in chromatophore suspensions with sulfide as the electron donor (about 7–12 M/h·mol Bchl) was approximately onetenth the rate of sulfide oxidation in whole cell suspensions. NAD photoreduction was inhibited by rotenone, carbonyl cyanide-m-chlorophenylhydrazone, and antimycin A. Sulfide reduced ubiquinone in the dark when added to anaerobic chromatophore suspensions. These results suggest that electron transport from sulfide to NAD involves an initial dark reduction of ubiquinone followed by reverse electron transport from ubiquinol to NAD mediated by NADH dehydrogenase.Abbreviations Bchl
bacteriochlorophyll
- CCCP
carbonyl cyanide-m-chlorophenylhydrazone
- MOPS
3(N-morpholino)-propane sulfonate
- Uq
ubiquinone 相似文献
100.
Kurt Kraeuchi Anna Wirz-Justice Tadaomi Morimasa Rosi Suetterlin-Willener Hans Feer 《Chronobiology international》1986,3(2):127-133
Specific binding of [3H]-imipramine in the rat suprachiasmatic nuclei, occipital cortex and caudate putamen underwent significant and replicable changes throughout 24 hr under a light-dark cycle or under constant conditions. Daily variations were also found in the medial and dorsal raphe nuclei and the lateral hypothalamus. Methamphetamine, a psychoactive drug with marked effect on circadian rhythms in physiological and hormonal parameters and adrenergic receptors, did not have any significant effect on imipramine binding rhythms in eight discrete brain regions. Thus a drug known to reduce serotoninergic neurotransmission did not change characteristics of the modulatory binding site related to serotonin uptake. 相似文献