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91.
催产素在脊髓水平对电针镇痛的影响 总被引:3,自引:0,他引:3
采用玻璃微电极胞外记录和脊髓表面给药的方法观察了催产素(OT)、抗催产素血清(AOTS)以及电针穴位对背角神经元伤害性诱发放电的影响。结果表明:电针穴位或脊髓表面施加OT可部分抑制脊髓背角神经元的伤害性诱发放电;在电针的基础上施加OT则明显加强电针的抑制效应;相反,用AOTS预处理后,电针的抑制作用放取消。提示OT在脊髓水平参与了对痛觉信息的调制,并与一定频率的针刺镇痛有关。 相似文献
92.
93.
The effects of orally administered prostaglandin E2, 16,16-dimethyl prostaglandin E2 and U-46619, an analogue of the prostaglandin endoperoxide PGH2, on gastric secretory volume, acid and mucus were studied in the rat. All of the compounds significantly increased the volume of gastric secretion, mucus secretion, measured as N-acetylneuraminic acid and mucus synthesis measured as the incorporation of [3H]-glucosamine into mucosal glycoprotein; however, only PGE2 and 16,16-dimethyl PGE2 inhibited acid secretion. U-46619, 1.5 mg/kg provided significant protection against ethanol-induced gastric ulcers, an effect that has been previously shown for the other two compounds. These studies provide additional evidence that prostaglandin induced mucosal protection may by related to an effect on mucus and on stimulation of nonparietal cell gastric secretion. Further study of these parameters may be important in the development of antiulcer drugs for long term clinical use. 相似文献
94.
P R Ortiz de Montellano J S Wei W A Vinson R Castillo A S Boparai 《Biochemistry》1977,16(12):2680-2685
Six 1-3H-labeled analogues of farnesyl pyrophosphate have been studied as potential substrates for yeast and rat liver squalene synthetases: 2-methylfarnesyl pyrophosphate (4), 3-demethylfarnesyl pyrophosphate (5), 7,11-dimethyl-3-ethyl-2,6,10-dodecatrienyl pyrophosphate (6), 6,7,10,11-tetrahydrofarnesyl pyrophosphate (7), 4-methylthiofarnesyl pyrophosphate (8), and 4-fluorofarnesyl pyrophosphate (9). Analogues 4 and 5 are enzymatically incorporated into 11-methylsqualene (10) and 10-demethylsqualene (11), respectively, even if no farnesyl pyrophosphate is added to the incubations. None of the other analogues gives nonpolar products with either the yeast or liver enzymes. No tritium is enzymatically released to the medium from any of the analogues, indicating that they are not accepted at the first (proton exchanging) site. The data rule out formation of dead-end presqualene pyrophosphate products with analogues as first, but not as second, substrates. Implications of these results for the enzyme active-site topology and mechanism are discussed. 相似文献
95.
Antibody against T-2 toxin was obtained after immunization of rabbits with bovine serum albumin-T-2 hemisuccinate conjugate. The antibody had greatest binding efficiency for T-2 toxin, less efficiency for HT-2, and least for T-2 triol. Cross-reaction of antibody with neosolaniol, T-2 tetraol, and 8-acetyl-neosolaniol was very weak. Diacetoxyscirpenol, trichodermin, vomitoxin, and verrucarin A essentially gave no cross-reaction with the antibody. The sensitivity of the binding assay for T-2 toxin detection was in the range of 1 to 20 ng per assay. Detailed methods for the preparation of the conjugate and the production of immune serum and methods for antibody determination are described. 相似文献
96.
Rotating disk voltammetry was used in this work to study the rates of reaction of ferricytochrome c with two very strong reductants, methyl and benzyl viologen. The rates of reaction for these reductants were found to be 4.0 × 107 and 5.4 × 107m?1s?1 at 24°C for benzyl and methyl viologen, respectively. The versatility of this method was demonstrated by the ease with which the activation parameters were obtained. The ΔH≠ and ΔS≠ were found to be 4.0 kcal/mol and ?10.6 cal/mol-K, respectively, for benzyl viologen. All the observed reaction rates were corrected for coulombic effects by the method of Wherland and Gray, and the electrostatically corrected rate constants were compared with the Marcus and Hopfield theories for electron transfer. The agreement was excellent for the tunneling theory but there were some discrepancies with the absolute Marcus theory. The relative Marcus approach worked quite well and, by taking into account the nonadiabaticity of the electron transfer, reasonable values were obtained for the absolute Marcus theory when realistic values of the self-exchange constants were used. 相似文献
97.
James E. Jumblatt Tien-Wen Tao Verena Schlup Jukka Finne Max M. Burger 《Biochemical and biophysical research communications》1980,95(1):111-117
Variants of B 16-F 1 mouse melanoma cells selected for resistance to wheat germ agglutinin (WGA) toxicity were found to have undergone a stable surface change correlated both to lectin resistance and reduced metastasizing potential. The surface alteration, as indicated by the increased electrophoretic mobilities of several lactoperoxidase-iodinated cell surface proteins in SDS-PAGE, was restricted to polypeptides able to interact with WGA. The availability of lectin-resistant melanoma cell variants having altered metastasizing behavior provides a promising approach to studies of the role of specific cell surface components in the metastasizing process. 相似文献
98.
Differential phosphorylation of band 3 and glycophorin in intact and extracted erythrocyte membranes
This report presents an analysis of the phosphorylation of human and rabbit erythrocyte membrane proteins which migrate in NaDodSO4-polyacrylamide gels in the area of the Coomassie Blue-stained proteins generally known as band 3. The phosphorylation of these proteins is of interest as band 3 has been implicated in transport processes. This study shows that there are at least three distinct phosphoproteins associated with the band 3 region of human erythrocyte membranes. These are band 2.9, the major band 3, and PAS-1. The phosphorylation of these proteins is differentially catalyzed by solubilized membrane and cytoplasmic cyclic AMP-dependent and -independent erythrocyte protein kinases. Band 2.9 is present and phosphorylated in unfractionated human and rabbit erythrocyte ghosts but not in NaI- or dimethylmaleic anhydride (DMMA)-extracted membranes. These latter membrane preparations are enriched in band 3 and in sialoglycoproteins. The NaI-extracted ghosts contain residual protein kinase activity which can catalyze the autophosphorylation of band 3 whereas the DMMA-extracted ghosts are usually devoid of any kinase activity. However, both NaI- and DMMA-extracted ghosts, as well as Triton X-100 extracts of the DMMA-extracted ghosts, can be phosphorylated by various erythrocyte protein kinases. The kinases which preferentially phosphorylate the major band 3 protein are inactive towards PAS-1 while the kinases active towards PAS-1 are less active towards band 3. The band 3 protein in the DMMA-extracted ghosts can be cross-linked with the Cu2+ -σ-phenanthroline complex. The cross-linking of band 3 does not affect its capacity to serve as a phosphoryl acceptor nor does phosphorylation affect the capacity of band 3 to form cross-links. In addition to band 2.9, the major band 3 and PAS-1, another minor protein component appears to be present in the band 3 region in human erythrocyte membranes. This protein is specifically phosphorylated by the cyclic AMP-dependent protein kinases isolated from the cytoplasm of rabbit erythrocytes. The rabbit erythrocyte membranes lack PAS-1 and the cyclic AMP-dependent protein kinase substrate. 相似文献
99.
Tao G. -Q. Letham D. S. Palni L. M. S. Summons R. E. 《Journal of Plant Growth Regulation》1983,2(1-4):89-102
Journal of Plant Growth Regulation - The metabolism of zeatin and that of 6-benzylaminopurine (BAP) have been compared in oat leaf segments in relation to the markedly differing ability of these... 相似文献
100.
以壳聚糖为载体,成二醛为交联剂将木瓜蛋白酶固定化。5%戊二醛在4-6℃下处理载体5h,加酶液(3.5mg/mL蛋白,pH7.2)固定12h,活力回收达32%,作用于酪蛋白的半衰期为36天,其表观K_m(酪蛋白)值为0.075%(W/V),溶液酶的K_m值为0.086%;最适pH7.0~7.5,溶液酶为7.0~8.5。固定化酶在pH8.5以下,溶液酶在9.0以下活力稳定。固定化酶在45℃以下,溶液酶在75℃以下稳定。用6mol/L脲洗脱固定化酶4次(5.5h)活力仍有54.5%。用固定化酶处理啤酒浊度比对照下降了1.5-3.7倍,蛋白质含量下降了44%,冷藏(4℃)120天无冷混浊现象发生并保持了啤酒原有风味和理化性状。 相似文献