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1.
Inhibitory effect of the flavonoid silymarin on the erythrocyte hemolysis induced by phenylhydrazine
A Valenzuela T Barría R Guerra A Garrido 《Biochemical and biophysical research communications》1985,126(2):712-718
The flavonoid silymarin, which is used as a therapeutical agent in the treatment of liver diseases, can inhibit the hemolysis and lipid peroxidation induced by phenylhydrazine on erythrocytes obtained from rats treated with the flavonoid. This effect is ascribed to the antioxidant properties as a free radical scavenger exhibited by the flavonoid. Silymarin failed to inhibit the glutathione depletion induced by phenylhydrazine on erythrocytes. It is proposed that the flavonoid acts at the membrane level of the cell avoiding the lipid peroxidative and fluidizing effect of phenylhydrazine. 相似文献
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A radioimmunoassay for the regulatory allylic steroid, 3 alpha-hydroxy-4-pregnen-20-one (3 alpha HP)
J P Wiebe K J Barr K D Buckingham 《The Journal of steroid biochemistry and molecular biology》1991,38(4):505-512
The allylic steroid, 3 alpha-hydroxy-4-pregnen-20-one (3 alpha HP), found in gonadal and brain tissues by radiotracer and chemical methods, had been shown to play a role in gametogenesis, gonadotropin secretion and brain excitability. Since no simple assay was available, a radioimmunoassay for 3 alpha HP was developed using [3H]3 alpha HP and an antiserum raised against 3 alpha HP-20-CMO conjugated to bovine serum albumin. The specificity of the assay for the 3 alpha allylic configuration of 3 alpha HP was confirmed by examining 32 other steroids; cross-reaction with steroids containing different configurations (including metabolites of 3 alpha HP such as progesterone) was less than 0.9%. A Scatchard plot indicated a Ka of 1.56 X 10(9) M-1. Inter- and intra-assay coefficients of variation were 13.1 and 4.5%, respectively. The sensitivity of the assay was 6 pg and the 50% intercept of the standard curve was approx. 123 pg. The measurement by RIA of 3 alpha HP from standard solutions and HPLC purified tissue extracts was confirmed qualitatively and quantitatively by GC/MS methods. The RIA method was employed to determine 3 alpha HP levels in cultured Sertoli cells and in serum of intact and ovariectomized adult rats. Although for most uses, chromatography would not be necessary, two possible methods are presented to enable the separation of 3 alpha HP from other interfering steroids prior to RIA. 相似文献
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Aspirin and acetaminophen use by pregnant women and subsequent child IQ and attention decrements 总被引:1,自引:0,他引:1
A P Streissguth R P Treder H M Barr T H Shepard W A Bleyer P D Sampson D C Martin 《Teratology》1987,35(2):211-219
In a longitudinal prospective study of 1,529 women pregnant in 1974-1975, aspirin and acetaminophen were the two medications most frequently taken during the first half of pregnancy (46 and 41%, respectively). In a selected cohort of 421 offspring of these women, examined at 4 years of age, maternal aspirin use during the first half of pregnancy was significantly related to IQ and attention decrements in the exposed children. Multiple regression analyses were used to statistically adjust for a variety of potentially confounding factors including demographic characteristics, child characteristics, other exposures, and lifestyle/environmental variables. Continuous dose-response and step-function parameterizations of aspirin exposure were both statistically significant and not clearly distinguishable from each other. The estimated aspirin effect is significantly greater for girls than boys. Aspirin effects on offspring function were found in the absence of effects on physical size both at birth and at 4 years. Maternal acetaminophen use was not significantly related to child IQ or attention. As this exploratory research originated from observations of a data set gathered for other purposes, it would be desirable to have these findings replicated in other studies. Further follow-up of the children at a later age is planned. 相似文献
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Human immunodeficiency virus reverse transcriptase expressed in transformed yeast cells. Biochemical properties and interactions with bovine tRNALys 总被引:11,自引:0,他引:11
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Radiometric assay for carboxypeptidase H (EC 3.4.17.10) and other carboxypeptidase B-like enzymes 总被引:2,自引:0,他引:2
Carboxypeptidase H, EC 3.4.17.10, also known as enkephalin convertase, carboxypeptidase E, and crino carboxypeptidase B, is an important enzyme involved in the biosynthesis of bioactive peptides. To assay the enzyme, tissues are homogenized in at least 20 vol (ml/g) of 0.025 M Tris-HCl buffer, pH 8, with 5 mg/ml of bovine serum albumin. After centrifugation, the supernatant is brought to pH 5.6 and centrifuged again. Following a 20-min preincubation in 2 mM CoCl2, the supernatant is incubated with 0.1 mM (final concentration) of the radioactive substrate [3H]benzoyl-Phe-Ala-Arg. The 100-microliters assay is stopped by the addition of 680 microliters of acetonitrile/0.25 M HCl (0.7/1). The 1.5-ml tube is transferred into a scintillation vial and is flushed with 4 ml of Econofluor, a water-immiscible scintillation fluid. The product, [3H]benzoyl-Phe-Ala, recovered in the organic phase, is counted directly with no interference from the substrate remaining in the aqueous phase. The blank is below 1%. Expressed in nanomoles per minute per milligram of tissue, the activity of the soluble enzyme in rat is 0.34 for striatum, 21.0 for pancreatic islet, 16.6 for anterior pituitary, 46.0 for intermediate pituitary, and 10.9 for neural pituitary. In every case 25 microM guanidinoethylmercaptosuccinic acid, an active site-directed inhibitor of carboxypeptidase H, completely inhibits the activity. 相似文献
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