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91.
92.
The concentration of VIP was measured radioimmunochemically in cerebrospinal fluid (CSF) from 14 healthy volunteers and from 22 patients with multiple sclerosis. Significantly lower levels of VIP was obtained in the patients (18 +/- 3 pmol/l) than in controls (37 +/- 4 pmol/l). There was no correlation between the level of VIP in CSF and other CSF parameters such as albumin. IgG or cell content; nor between VIP concentration and the physical handicap or neuropsychiatric symptoms. There was a trend towards lower values of VIP in patients with steadily progressing rather than intermittent course of the disease but the difference between the groups was not significant. 相似文献
93.
Sara S. Tynan Niels H. Andersen Max T. Wills Laurence A. Harker Stephen R. Hanson 《Prostaglandins & other lipid mediators》1984,27(5):683-696
The ω-chain variant analogs of prostacyclin (PGI2) and PGD2 in which the n-amyl side-chain has been replaced by a cyclohexyl group have been prepared and their cardiovascular activities have been compared to those of BW-245C(Fig. 1)(1) a potent anti-aggregatory vasodilator bearing a cyclohexyl-terminated side-chain on a hydantoin skeleton. The cyclohexyl group has little effect on PGI2, but converts PGD2 to a long lasting hypotensive agent and increases the platelet anti-aggregatory potency of PGD2 by a factor of 8. The prostaglandin antagonist N-0164 selectively blocks the anti-aggregatory actions of PGD2, cyclohexyl-PGD2, and BW-245C; with essentially no effect on PGI2, cyclohexyl-PGI2 and PGE2 at comparably effective doses. The latter observation is contrary to an earlier report by MacIntyre (2,3), but supports the view that the anti-aggregatory effect of high doses of PGE2 () is mediated by the PGI2 receptor (4). The hydantoin acts at the platelet PGD2 receptor. 相似文献
94.
Platelet-derived growth factor stimulates chemotaxis and nucleic acid synthesis in the protozoan Tetrahymena 总被引:2,自引:0,他引:2
Platelet-derived growth factor (PDGF) is in concentrations of a few nanograms per ml a very active chemoattractant for the free-living ciliated protozoan Tetrahymena; at the same time it induces a rapid increase in incorporation of radioactive nucleic acid precursors into RNA and DNA. We find it remarkable that this lower eukaryote responds to platelet-derived growth factor in very much the same way as fibroblastic cells. 相似文献
95.
Yeast RNA polymerase III. Chromatographic, catalytic and DNA-binding properties are highly dependent on the type of anion 总被引:4,自引:0,他引:4
The chromatographic, catalytic and DNA-binding properties of yeast RNA polymerase III are highly affected by both concentration and type of salt. The type of anion is an especially important modulating factor for the enzymological properties of the enzyme. When acetate or sulfate anions are substituted for chloride anions, RNA polymerase III exhibits a higher affinity for DEAE-Sephadex A25, becomes able to transcribe DNA at relatively high ionic strength and shows a significant increase in the binding strength to DNA. A quantitative analysis of the binding of the enzyme to single-stranded DNA shows that the number of ionic contacts in the complex is not affected by the type of anion, but the nonionic contribution to the binding constant is significantly increased when acetate is substituted for chloride. 相似文献
96.
Partial purification, characterization and translation in vitro of rat liver metallothionein messenger ribonucleic acid. 总被引:8,自引:1,他引:7 下载免费PDF全文
Poly(A)+ (polyadenylated) mRNA coding for metallothioneins was purified 13-fold from rat liver polyribosomes and was identified by its ability to direct the biosynthesis of these proteins in a wheat-germ cell-free system. The carboxymethylated products of the protein-synthesizing system in vitro were analysed with sodium dodecyl sulphate/20% polyacrylamide-gel electrophoresis. The labelled compounds [3H]serine and [35S]cysteine were incorporated at high specific radioactivity into proteins that co-migrated with authentic metallothioneins. No [3H]leucine incorporation was found, in agreement with the amino acid composition of the metallothioneins. Metallothionein mRNA had a sedimentation coefficient of 9 S and carried a maximum of four ribosomes. At 5 h after a subcutaneous injection of ZnCl2 or CdCl2 (10 mumol/kg body wt.), the amount of this mRNA increased approx. 2- and 4-fold respectively, on the basis of translation in vitro. The increase in metallothionein mRNA (defined by translation in the wheat-germ system) was transient and, after CdCl2 treatment, fell back to control values by 17 h. Metallothioneins constituted a maximum of 0.8% of the total protein products synthesized in the wheat-germ system by total mRNA isolated from rat liver after CdCl2 treatment. 相似文献
97.
The measurement of DNA in tissue samples fixed in ethanol/acetic acid is described. Small, fixed tissue samples are digested by warm alkaline treatment followed by neutralization with HCl, and DNA is determined by complex formation with the dye ethidium bromide (EB). When standard DNA from calf thymus was treated similarly, a hyperchromicity of 8–12% and a reduction in fluorescence intensity of the EB-DNA complex to 55% was observed. The NaOH concentration (0.5–2.0 mol/liter) or the temperature (50–60°C) used for the digestion of tissue, as well as subsequent ribonuclease or protease treatment had no effect on the observed tissue DNA concentrations. 相似文献
98.
Helge Klaus Körner 《Oecologia》1982,55(2):248-250
Summary Specimens of the fish louse Anilocra physodes L. from the Mediterranean Sea exhibited a striking colour asymmetry in their dorsal pigmentation: one longitudinal half of their back was dark, the opposite half was lightcoloured. The dark side corresponded with the physiological upper side when the fish louse was attached to the flank of a host fish.The colour pattern derives from the different shape (stellate/punctate) of chromatophores, which lie immediately beneath the epidermis. The appearance and distribution of the chromatophore stages indicate the possibility of physiological colour change in Anilocra. In this way the fish louse probably achieves adaptive countershading and thus additional protection from predators, advantageous for both parasite and host. 相似文献
99.
100.
(1) Sulfhydryl reactivity and electron spin resonance spectra of nitroxide maleimide spin labels, covalently attached to sarcoplasmic reticulum ATPase, were examined on both detergent-solubilized and membranous material. Monomeric and oligomeric ATPases were prepared by the use of dodecyloctaethylene glycol monoether as a solubilizing detergent. (2) Immediately after solubilization, the reaction curve of nonomeric ATPase with 5,5'-dithiobis(2-nitrobenzoate) was characterized by positive cooperativity (S-shaped as a function of time). In contrast, the SH reactivity of both oligomeric and membranous ATPases obeyed usual first-order kinetics and could be analyzed in terms of three classes of reactive site. All enzymatically active ATPase preparations responded to addition of ADP with a decrease in SH reactivity. During enzymatic inactivation of monomeric ATPase, the SH-modification rate was dramatically enhanced with loss of cooperative features. Ca2+ removal from the high-affinity sites stimulated SH reactivity before inactivation had taken place. (3) ESR spectroscopy indicated less motional constraints on monomeric than on oligomeric and membranous ATPases. Arrhenius plots of ESR spectral parameters suggest a conformational transition in both membranous and solubilized ATPases at about 22 degrees C. The transition was also present in EGTA-, but not in heat-inactivated ATPase. Although SH reactivity of monomeric ATPase was dramatically enhanced by EGTA inactivation, the results of ESR, circular dichroism and analytical ultracentrifugation experiments indicate limited conformational changes induced by EGTA treatment. (4) The data indicate marked differences in the properties of monomeric ATPase on the one hand and oligomeric and membranous enzymes on the other hand. They are consistent with previous functional evidence for the presence of ATPase in an associated state in the membrane (M?ller, J.V., Lind, K.E. and Andersen, J.P. (1980) J. Biol. Chem. 255, 1912-1920). 相似文献