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1.
O.L. Tulp  G.I. Meeker 《Steroids》1976,28(2):239-246
Studies were conducted to determine the fate of 15α-hydroxyprogesterone in human placental tissue. Tritiated 15α-hydroxyprogesterone was perfused through normal human placentas in situ at the time of Cesarean section and incubated with a 10,000x g microsomal supernate of the placenta in vitro. 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   

2.
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 invivo nor in GPI exposed to morphine invitro. However, the levels of some β-endorphin fragments i.c. γ-endorphin and des-tyrosine-γ-endorphin were elevated after morphine treatment invitro and invivo respectively. It is suggested that β-endorphin and its fragments are involved in homeostatic processes during development of opiate tolerance.  相似文献   

3.
Studies were conducted to determine the influence of some LHRH analogues on gonadotropic hormone (GtH) secretion in two species of trout. The observations indicated that synthetic LHRH and various stimulatory LHRH analogues are approximately equipotent in these fish. This is an unexpected result considering the superactive properties of these analogues demonstrated in mammals. An inhibitory LHRH analogue was also tested in the trout with the result that powerful inhibition of LHRH induced GtH release was obtained.  相似文献   

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History and ClinicalSigns: Herds infected with Trichomonasfetus have histories of infertility, occasional abortions, and pyometra.GrossLesions: 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.MicroscopicLesions: There are no specific microscopic lesions.CulturalProcedures: It is ordinarily not necessary to culture T.fetus in order to demonstrate its presence in placental fluids and/or abomasal contents.SerologicProcedures: There are no suitable seroligic procedures for diagnosing Trichomoniasis.SpecialProcedures: Wet mounts of abomasal contents and/or placental fluids are examined microscopically for T.fetus.PreferredDiagnosticProcedures: Demonstrate the presence of T.fetus by microscopic examination of wet mounts of placental fluids and/or abomasal contents.  相似文献   

8.
The dinoflagellate Glenodiniumhallii 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   

9.
Recently, 1-β-D-arabinofuranosylcytosine-5′-diphosphate-DL-1,2-dipalmitin (VIa) was reported to inhibit the growth of L51784 cells in mice and of human colon carcinoma HCT-15 cells, also in mice. This paper describes the synthesis of a single diastereomer by conversion of 1-β-D-arabinofuranosylcytosine 5′-monophosphate (II) to the nucleoside 5′-phosphomorpholidate (III), followed by reaction with L-α-dipalmitoylphosphatidic acid (IV) to give 1-β-D-arabinofuranosylcytosine-5′-diphosphate-L-1,2-dipalmitin (V) in good yield. The separation of the product is described and its characterization by chromatography, elemental analysis, and spectroscopic methods. The lipophilic nature of V renders it insoluble in aqueous media and a method of sample preparation utilizing sonication techniques is described which provides a clear solution suitable for biological evaluation. In addition, the ability of V to inhibit the invitro growth of L1210 cells and of mouse myeloma MPC 11 cells is desscribed and compared with 1-β-D-arabinofuranosylcytosine (I) and other lipophilic prodrugs of I.  相似文献   

10.
The substrate specificities of the endo-β-N-acetylglucosaminidases from Diplococcus pneumoniae and Streptomyces griseus were compared and found to differ considerably. The enzyme from D. pneumoniae 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 S. griseus 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 S. griseus enzyme, thus broadening its substrate range to encompass most of those substrates hydrolyzed by the D. pneumoniae endoglycosidase.  相似文献   

11.
The effects of danazol on steroidogenesis invitro 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 invitro.  相似文献   

12.
The effects of estradiol-17β treatment on plasma lipid levels, liver lipid and glycogen reserves were examined during different phases of the reproductive cycle in goldfish, Carassiusauratus. Estrogen therapy resulted in increased plasma and hepatic lipid levels except during the spawning season. Hepatic glycogen deposits were depleted by estradiol injections during all seasons. Treatment of fish with the estrogen antagonist, CI-628, during the spawning season caused a reduction in plasma and liver lipid levels. Electrophoretic studies conducted during the post-spawning season showed that estrogen induces the appearance of a specific lipoprotein, probably a yolk precursor, in the serum and liver of goldfish.  相似文献   

13.
L-leucinthiol (2-amino-4-methyl-1-pentanethiol) was designed as an inhibitor of leucine aminopeptidase by analogy with sulfhydryl inhibitors of other zinc-containing peptidases. It was synthesized from L-leucinol and shown to be a potent competitive inhibitor of the microsomal aminopeptidase from porcine kidney (Ki = 2.2 × 10?8M). The results suggest that the mechanism of aminopeptidase may be similar to that of other metalloproteases.  相似文献   

14.
The effects of intraperitoneal administration of (S)-4-amino-5-fluoropentanoic acid, a mechanism-based covalent inactivator of γ-aminobutyric acid transaminase (GABA-T), on whole brain GABA metabolism in mice were investigated. A dose-dependent and time-dependent irreversible inactivation of GABA-T was observed with a concomitant increase in whole brain GABA levels. The compound exhibited no in vitro nor in vivo time-dependent inhibition of glutamate decarboxylase (GAD), alanine transaminase, or aspartate transaminase (Asp-T). It was, however, a potent competitive reversible inhibitor of GAD and a weak competitive inhibitor of Asp-T. The chloro analogue, (S)-4-amino-5-chloropentanoic acid, was ineffective.  相似文献   

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3′,4′-Dideoxykanamycin B, the kanamycin B derivative that is active against resistant bacteria, was prepared from kanamycin B viaN-tosylation, 3′,4′-O-sulphonylation, 3′,4′-unsaturation, and hydrogenation. The unsaturated intermediate was obtained from the 3′,4′-di-O-sulphonyl derivatives by the action of sodium iodide in N,N-dimethylformamide; if zinc dust was added in this reaction, aziridine derivatives were formed, Removal of the tosyl group was successfully performed by using sodium in ammonia-ethylamine.  相似文献   

17.
A new exo-β-glucanase, sporulation-specific, was purified from sporulating S. cerevisiae (AP1, aα). Characterization of this new activity shows that the enzyme is a glycoprotein with substrate specificities, kinetic parameters and aminoacid composition clearly different from those of its vegetative counterpart.  相似文献   

18.
The binding of progesterone, 17β-estradiol and 19-nortestosterone acetate to the Δ5-3-ketosteroid isomerase from Pseudomonastestosteroni has been investigated by the technique of equilibrium dialysis. Under the conditions used, all three steroids formed 2:1 complexes with each molecule of enzyme dimer (M.W. = 26,788). No evidence of any cooperative binding phenomena was obtained. The dissociation constants of the enzyme steroid complexes at 25°C were: progesterone, 2.2 μM; estradiol, 2.5 μM; 19-nortestosterone acetate, 9.2 μM.  相似文献   

19.
α-Glucosidase was membrane bound during exponential growth of Bacilluslicheniformis 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. Invitro 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   

20.
Sucrose and 1,2-O-isopropylidene-α-d-glucofuranose (1) were oxidised with bromine in aqueous solution at pH 7 and room temperature. The resulting keto derivatives were converted into their more-stable O-methyloximes, which were characterised by spectroscopic and chromatographic methods. Oxidation of 1 occurred at C-3 and C-5, with a preference for C-5. In the sucrose derivatives isolated after oxidation, those having a keto group in the glucopyranosyl moiety preponderated. The axial fructofuranosyl aglycon protects position 3 in the glucopyranosyl group and oxidation occurs only at C-2 and C-4. Small amounts of sucrose oxidised at C-3 in the fructofuranosyl moiety were also found.  相似文献   

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