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1.
The dinoflagellate was investigated for its sterol composition. Five of the six sterols were isolated and identified as cholest-5-en-3β-ol, (24ξ)-24-methylcholest-5-en-3β-ol, stigmasta-5,22-dien-3β-ol, (22E,24R)-4α,23,24-trimethyl-5α-cholest-22-en-3β-ol, and 4α,23ξ,24ξ-trimethyl-5α-cholestan-3β-ol. 相似文献
2.
Studies were conducted to determine the fate of 15α-hydroxyprogesterone in human placental tissue. Tritiated 15α-hydroxyprogesterone was perfused through normal human placentas at the time of Cesarean section and incubated with a 10,000x g microsomal supernate of the placenta . In both systems the substrate, but no additional metabolites were identified. These findings indicate that 15α-hydroxyprogesterone is not metabolized during its passage in the human term placenta, and suggests that because of its fetal origin clinical measurements of 15α-hydroxyprogesterone may provide a valuable index to the status of fetal viability. 相似文献
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The isolated myenteric plexus-longitudinal muscle of the guinea-pig ilem (GPI) was used as testsystem to study the influence of chronic morphine treatment on the levels of enkephalins, β-endorphin and some of its fragments. The peptides were assayed by means of a combination of high pressure liquid chromatography and radioimmunoassays. It was found that the levels of methionine- and leucine-enkephalin and β-endorphin were not altered by chronic morphine treatment of guinea-pigs nor in GPI exposed to morphine . However, the levels of some β-endorphin fragments i.c. γ-endorphin and des-tyrosine-γ-endorphin were elevated after morphine treatment and respectively. It is suggested that β-endorphin and its fragments are involved in homeostatic processes during development of opiate tolerance. 相似文献
6.
John W. Kendrick 《Theriogenology》1976,5(3):150-152
and : Herds infected with have histories of infertility, occasional abortions, and pyometra.: There are no specific gross lesions in the fetus. The fetuses are usually aborted in the first half of gestation and may or may not be accompanied by the placenta.: There are no specific microscopic lesions.: It is ordinarily not necessary to culture in order to demonstrate its presence in placental fluids and/or abomasal contents.: There are no suitable seroligic procedures for diagnosing Trichomoniasis.: Wet mounts of abomasal contents and/or placental fluids are examined microscopically for .: Demonstrate the presence of by microscopic examination of wet mounts of placental fluids and/or abomasal contents. 相似文献
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Anthony L. Tarentino Frank Maley 《Biochemical and biophysical research communications》1975,67(1):455-462
The substrate specificities of the endo-β-N-acetylglucosaminidases from and were compared and found to differ considerably. The enzyme from released Asn-GlcNAc-Fuc-containing glycopeptides from exoglycosidase-treated acidic IgM glycopeptides but was limited in its capacity to hydrolyze ovalbumin glycopeptides larger than Asn(GlcNAc)2(Man)5. In contrast, the enzyme from hydrolyzed this and larger neutral oligosaccharides but could not hydrolyze the above fucose-containing IgM glycopeptides. Removal of the fucose residue, however, converted the latter to an active substrate for the enzyme, thus broadening its substrate range to encompass most of those substrates hydrolyzed by the endoglycosidase. 相似文献
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Studies were conducted to determine the influence of some LHRH analogues on gonadotropic hormone (GtH) secretion in two species of trout. The observations indicated that synthetic LHRH and various stimulatory LHRH analogues are approximately equipotent in these fish. This is an unexpected result considering the superactive properties of these analogues demonstrated in mammals. An inhibitory LHRH analogue was also tested in the trout with the result that powerful inhibition of LHRH induced GtH release was obtained. 相似文献
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Robert L. Barbieri Rapin Osathanondh Jacob A. Canick Robert J. Stillman Kenneth J. Ryan 《Steroids》1980,35(3):251-263
The effects of danazol on steroidogenesis in the 16–20 week old human fetal adrenal were examined by studying: 1) danazol binding to adrenal microsomal and mitochondrial cytochrome P-450, and 2) enzyme kinetics of danazol inhibition of the adrenal microsomal 21-hydroxylase and the mitochondrial llβ-hydroxylase. The addition of danazol to preparations of adrenal microsomes or mitochondria elicited a type I cytochrome P-450 binding spectrum. Danazol bound to microsomal cytochrome P-450 with a high affinity apparent spectral dissociation constant (Kg) of 1 μM and with a lower affinity K's of 10 μM. Danazol bound to mitochondrial cytochrome P-450 with a Kg of 5 μM. In addition, danazol competitively inhibited the microsomal 21-hydroxylase (apparent enzymatic inhibition constant KI = 0.8 μM) and the mitochondrial 11β-hydroxylase (KI = 3 μM). These findings demonstrate that low concentrations of danazol directly inhibit steroidogenesis in the human fetal adrenal . 相似文献
12.
The sterol mixture isolated from the marine alga consists mainly of Δ5,7-dienes which account for 80% of the free sterols. Eighteen different sterols were detected, including a novel sterol with the rare Δ23-unsaturation, viz. 24-ethylcholesta-5,7,23Z-trien-3β-ol. 相似文献
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Adult beagle dogs, castrated one month previously, were treated with 5α-androstane-3α, 17α-diol (total dose 300 mg) over a period of one month. Examination of the prostate after treatment showed no significant change in size, weight or histological appearance from the castrate dog prostate. Subsequent administration of 5α-androstane-3α, 17β-diol (300 mg) over the same period of time resulted in restoration of the prostate size, weight and histological appearance to that of the normal intact dog prostate. It is concluded that exogenously administered 5α-androstane-3α, 17α-diol does not promote prostatic growth in the castrate beagle dog. 相似文献
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4-Methyl-α-ethyl-tyramine and its 4, α-dimethyl analogue release 5-HT from human blood platelets . At lower concentrations they inhibit the uptake of 5-HT into platelets. Tricyclic antidepressant drugs do not block 5-HT release by these compounds. On removal of the depletor, platelets recover their ability to take up 5-HT; platelets preloaded with exogenous 5-HT lose the same proportion of amine as those containing only endogenous 5-HT. Tetrabenazine behaves similarly, but its actions are partial, whereas those of the tyramines are more complete. The temperature dependence of spontaneous and drug-induced 5-HT release has been measured. The results are discussed in terms of the action of these drugs and with special reference to the use of human blood platelet as a model of a 5-HT-containing nerve ending. 相似文献
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A. Ian Scott S.L. Lee W. Wan 《Biochemical and biophysical research communications》1977,75(4):1004-1009
The “ajmalicine synthetase” system of has been partially purified from callus, seedlings and mature plants. On gel filtration of the cell-free extract, four β-D-glucosidase isozymes were observed in seedlings and plants. Only two were present in the callus. A protein peak at 55,000 daltons in all three materials was capable of synthesizing ajmalicine from tryptamine and secologanin in the presence of NADPH. This “ajmalicine synthetase” rapidly lost its ability to synthsize ajmalicine, but retained the β-glucosidase activity. 相似文献
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The addition of cholic acid to growing cultures of species V.P.I. 12708 caused a 25 and 46-fold increase in 7α-dehydroxylation activity using cell extracts or whole cell suspensions, respectively. Bile acid conversion rates using either [14C]-cholic acid or [14C]-chenodeoxycholic acid as substrates increased at approximately the same rate when either cholic or chenodeoxycholic acid was added to growing cultures as inducer. The induction of 7α-dehydroxylase activity was highly specific requiring a free C-24-carboxyl group and an unhindered 7α-hydroxy group on the B ring of the steroid nucleus. Unexpectedly, cholic acid also rapidly induced NADH:flavin oxidoreductase activity in growing cultures of this bacterium. 相似文献
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M. Thirunavukkarasu Fergus G. Priest 《Biochemical and biophysical research communications》1983,114(2):677-683
α-Glucosidase was membrane bound during exponential growth of but was released into the medium during stationary phase. It could be partially removed from exponential phase cells by washing with NaCl (0.5 M). α-Amylase was exclusively extracellular and could not be detected in cells. Polysomes were prepared from exponential phase cells and separated into membrane bound and soluble fractions. chain completion and immunoprecipitation showed that α-glucosidase and α-amylase were synthesized by membrane bound and not by soluble ribosomes. 相似文献
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Microsomal 11α-hydroxylation of progesterone in : Part I: Characterization of the hydroxylase system
C.R. Jayanthi Prema Madyastha K.Madhava Madyastha 《Biochemical and biophysical research communications》1982,106(4):1262-1268
Microsomes (105,000xg sediment) prepared from induced cells of was found to hydroxylate progesterone to 11α-hydroxyprogesterone (11α-OHP) in high yields (85–90% in 30 min.) in the presence of NADPH and O2. The pH optimum for the hydroxylase was found to be 7.7. However, for the isolation of active microsomes grinding of the mycelium should be carried out at pH 8.3. Metyrapone, carbon monoxide, SKF-525A, p-CMB and N-methyl maleimide inhibited the hydroxylase activity indicating the involvement of cytochrome P-450 system. The inhibition of the hydroxylase by cytochrome and the presence of high levels of NADPH-cytochrome reductase in induced microsomes suggest that the reductase could be one of the components in the hydroxylase system. 相似文献
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Richard B. Silverman Mark A. Levy A.Jabbar Muztar James D. Hirsch 《Biochemical and biophysical research communications》1981,102(1):520-523
Intraperitoneal injection into mice of varying concentrations of (S)-4-amino-5-fluoropentanoic acid ((S)-AFPA) produces a dose-dependent irreversible decrease in brain γ-aminobutyric acid-α-ketoglutaric acid aminotransferase (E.C. 2.6.1.19) activity. Concomitant with this inactivation is an increase in whole brain γ-aminobutyric acid (GABA) levels. Four hours after a dose of 100 mg/kg body weight of (S)-AFPA to mice, endogenous brain GABA concentrations increase to 16 times that of the untreated animals and the enzyme activity decreases to 20% that of the controls. The binding of (S)-AFPA to GABA receptors was more than three orders of magnitude poorer than for GABA itself. 相似文献
20.
Hiroshi Kanazawa Toshiaki Kayano Tatsuya Kiyasu Masamitsu Futai 《Biochemical and biophysical research communications》1982,105(4):1257-1264
The 1855-nucleotide long DNA sequence of part of the gene cluster for the proton-translocating ATPase from was determined by the method of Maxam-Gilbert. The sequence covers the genes for the β and ε subunits of F1 along with the flanking region. The amino acid sequence of these subunits deduced from the nucleotide sequence indicates that the β and ε subunits have 459 and 138 amino acids, respectively. The possible secondary structure of the both subunits was estimated from the deduced primary structures. A possible nucleotide binding site in the β subunit is also discussed on the basis of the primary and secondary structures. The codons used in the genes for all the components of F1F0 were different in different genes, suggesting that the amount of each subunit in the F1F0 is determined to some extent on a translational level. 相似文献