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41.
Production of platelet-activating factor by washed rabbit platelets under stimulation with the ionophore A23187 was investigated utilizing two groups of platelet preparations. The first platelet preparation contained 0.03 +/- 0.02% contaminating white cells, while the second preparation contained 0.48 +/- 0.27% white cells. The latter preparation produced platelet-activating factor, mainly 1-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine, 8.3 +/- 6.3 pmol (mean +/- standard deviation) with a range of 2.6 to 21.4 pmol (n = 9), followed by small quantities of 1-octadecenyl- and 1-octadecyl-2-acetyl-sn-glycero-3-phosphocholine. In contrast, there was no production of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine by the former platelet preparation having 0.03% leukocytes. These quantitative analyses were carried out by the selected ion monitoring technique and it was concluded that it is necessary to consider the presence of contaminating white cells in studies on the production of platelet-activating factor by platelets. 相似文献
42.
Hiroko Nashimoto Akiko Miura Haruo Saito Hisao Uchida 《Molecular & general genetics : MGG》1985,199(3):381-387
Summary Temperature-sensitive (ts) mutations were isolated within a ribosomal protein gene (rpsL) of Escherichia coli K12. Mutations were mapped by complementation using various transducing phages and plasmids carrying the rpsL gene, having either a normal or a defective promoter for the rpsL operon. One of these mutations, ts118, resulted in a mutant S12 protein which behaved differently from the wild-type S12 on CM-cellulose column chromatography. Suppressors of these ts mutations were isolated and characterized; one was found to be a mutation of a nonribosomal protein gene which was closely linked to the RNAase III gene on the E. coli chromosome. This suppressor, which was recessive to its wild-type allele, was cloned into a transducing phage and mapped finely. A series of cold-sensitive mutations, affecting the assembly of ribosomes at 20°C, was isolated within the purL to nadB region of the E. coli chromosome and one group, named rbaA, mapped at the same locus as the suppressor mutation, showing close linkage to the RNAase III gene. 相似文献
43.
A. Ajima T. Yoshimoto K. Takahashi Y. Tamaura Y. Saito Y. Inada 《Biotechnology letters》1985,7(5):303-306
Summary A hydrophobic substrate, 10-hydroxydecanoic acid having two functional groups (–OH and –COOH) in the molecule, was polymerized by ester bond formation with the polyethylene glycol-modified lipase in a transparent benzene solution. The polymer of 10-hydroxydecanoic acid was linearly elongated under a quite mild condition. 相似文献
44.
We examined seven strains, comprising five serotypes, of Cryptococcus neoformans to determine what constituents of the organisms are responsible for pathogenicity and virulence in BALB/c mice. C. neoformans strains were divided into three virulence classes by survival rates after intravenous inoculation of 1 X 10(5) or 1 X 10(7) viable cells, and virulence was found not to be correlated with serotype or capsular size. C. neoformans cells resisted phagocytosis in different degrees in the presence of normal serum. Sensitivity of the C. neoformans strains to singlet oxygen ranged from resistance to susceptibility. Histological examination revealed that a weakly encapsulated virulent strain induced inflammatory responses with granuloma formation in the liver, lung, and kidney in addition to formation of cystic foci in the brain. In contrast, although the heavily encapsulated virulent strain produced granulomatous lesions in the liver, this strain preferably produced mucinous cystic foci in the lung, kidney, and brain. Correlation between virulence, and biological, histopathological and physiological evidence suggests that C. neoformans strains are endowed with the implicated multiple pathogenic constituents in various degrees and proportions. The following are suggested as the most important pathogenic constituents: a polysaccharide capsule responsible for resistance to phagocytosis and formation of cystic foci; a cell surface structure for responsible for resistance to intra- or extracellular killing and induction of the granulomatous lesion; a growth rate suitable for interacting with phagocytic elimination. 相似文献
45.
Spider toxin (JSTX) on the glutamate synapse 总被引:1,自引:0,他引:1
A new neurotoxin (JSTX) was separated from spider (Nephila clavata, Joro spider) venom. JSTX irreversibly suppressed the excitatory postsynaptic potential (EPSP) and the glutamate potential in the lobster neuromuscular junction with high degree of specificity. The threshold concentration for suppressing EPSPs corresponds to a small fraction of the toxin in a venom gland, roughly estimated as low as 10(-10) M/l. 10(-10) M/l. In the giant synapse of squid stellate ganglion JSTX suppressed EPSPs without affecting the antidromic response. Glutamate-induced membrane depolarization was blocked by JSTX. In mammalian brain slice preparation, JSTX suppressed the orthodromic spike response but failed to affect on the antidromic spike in the hippocampal pyramidal neuron of CA1 and CA3 region. The above results strongly support the view that the squid giant synapse and synapses in the hippocampal pyramidal neuron are mediated by glutamate. 相似文献
46.
A stable clone of C57BL/6 (H-2b) radiation leukemia virus transformed ovalbumin (OVA)-specific murine T-cell lymphoma cells was able to mediate carrier-specific helper activity. The ability of these lymphoma cells to express helper activity for both primary and secondary hapten-specific B-cell responses was analyzed in nonirradiated normal or hapten-primed recipients. The lymphoma cells augmented anti-hapten responses in a carrier-specific manner; no bystander effects were noted. Helper activity was primarily noted in the IgG responses. The genetic restrictions affecting the expression of lymphoma-mediated helper activity were also analyzed. The pattern of restriction indicated that genes in the H-2 complex controlled the expression of helper activity; disparities at the Igh complex failed to influence helper activity. The cellular site of the H-2 restriction was between the antigen-presenting cells and the T-cell lymphoma not between the T and B cells. Precise intra-H-2 mapping of the gene(s) which control expression of lymphoma-mediated helper activity was attempted. Although most of the data were consistent with localization of the gene(s) to the I-A region, anomolous responses were noted in one strain. 相似文献
47.
48.
A method for the preparation of a highly purified sample of rabbit blood monocytes is described. The metabolism of arachidonic acid (AA) in these cells was studied. Mononuclear cells were prepared by centrifugation on Ficoll-Paque gradients and the monocytes were obtained by further centrifugation and adherence onto plastic culture dishes. These procedures provided a preparation which contained 95% monocytes (non-specific esterase positive). Incubation of [1-14C]-AA with these cells produced four major metabolites which were separated by TLC; these corresponded to prostaglandin (PG) D2, thromboxane (TX) B2, 12-hydroxyheptadecatrienoic acid (HHT) and 12-/15-hydroxyeicosatetraenoic acid (HETE). A minor product which co-migrated with PGE2 was also detected but neither 6-keto-PGF1 alpha nor PGF2 alpha were detected. Also, there was no evidence of the formation of 5-lipoxygenase products (5-HETE and LTB4) by rabbit monocytes with or without calcium-ionophore A23187-stimulation. The production of PGD2, TXB2 and PGE2 was further confirmed by analyzing [3H]-AA metabolites using high-performance liquid chromatography (HPLC) with tritiated standards as references. The biosynthesis of these compounds from endogenous substrate in A23187-stimulated monocytes was confirmed by specific radioimmunoassays with or without prior HPLC separation. The synthesis of immunoreactive LTB4 and LTC4 by A23187-stimulated cells was also monitored and found to be relatively low. The synthesis of PGD2, TXB2 and PGE2 from both exogenous and endogenous substrate was suppressed by treatment of the monocytes with indomethacin (10(-6) M). 相似文献
49.
F Kitame K Nakamura A Saito Y Suzuki H Sinohara M Homma 《Biochemistry international》1986,12(5):649-652
Rat alpha-1- and alpha-2-macroglobulins as well as rat murinoglobulins I and II were shown to inhibit hemagglutination by influenza C virus. In marked contrast, neither alpha-macroglobulins nor murinoglobulins from mouse or guinea pig plasma had the inhibitory activity. These results suggest that the hemagglutination-inhibiting activity of rat alpha-macroglobulins or murinoglobulins is not related to their protease-binding capacity. 相似文献
50.
N Shinohara H Tanaka T Saito J Deguchi K Soda T Sugiyama Y Ishimaru S Sonoda 《Japanese journal of medical science & biology》1983,36(3):191-197
Eighty-two cases of typhoid fever were found in Matsuyama city in the period from 1974 to 1981. Seventy-six cases were found to be infected with Salmonella typhi other three with Salmonella paratyphi A, and the remaining three were diagnosed only clinically. The strains of S. typhi isolated from these patients showed such a variety of Vi-phage types as D1, D2, E1, M1, 53 and degraded Vi-positive strain (DVS). The concurrent survey of the city sewage and river waters for typhoid bacilli was conducted with total 578 samples taken therefrom. S. typhi was isolated from 120 of those samples. The Vi-phage types of the isolates were closely related with those of the isolates from the patients. The periodical examinations of the city sewage and the draining river may serve as a useful means for the controlling typhoid fever epidemics. 相似文献