共查询到20条相似文献,搜索用时 15 毫秒
1.
John W. Wilks Kristi K. Forbes Jerome F. Norland 《Prostaglandins & other lipid mediators》1973,3(4):427-437
Prostaglandin F2α (PGF2α) did not alter the biosynthesis of progesterone by slices of luteinized rat ovaries when used in concentrations from 1 to 10,000 ng/ml of incubation medium; likewise, PGF2α did not affect the incorporation of acetate-1-14C into progestins. PGF1α, 15-keto PGF2α, and PGE1 did not alter the biosynthesis of progesterone by luteinized rat ovaries; PGE2 inhibited the production of progesterone when used at a concentration of 10 μg/ml, but not at lower doses. PGF2α in combination with luteinizing hormone (LH) enhanced the metabolism of progesterone to 20α-hydroxypregn-4-en-3-one in luteinized rat ovaries. Interestingly, PGF2α, at a high concentration of 10 μg/ml, did stimulate progesterone biosynthesis by slices of ovarian tissue from immature rats hormonally primed to simulate “pseudopregnancy,” suggesting a steroidogenic action of prostaglandins on the ovarian follicular or interstitial cell. PGF2α (10 μg/ml) did not stimulate the biosynthesis of progesterone or 20α-hydroxypregn-4-en-3-one by slices of rabbit corpora lutea or rabbit ovarian interstitial tissue. It is concluded that prostaglandins do not stimulate progestin biosynthesis in rat luteal tissue. 相似文献
2.
Yolk free blastoderms of chick embryo were incubated 3 or 22 hours with labeled pregnenolone, progesterone, 17-hydroxyprogesterone, dehydro-epiandrosterone, androstenedione, testosterone and estradiol-17β. Metabolites and unconverted substrates were found both in the incubation medium and in the cells. Enzymes responsible for identified conversions were: 17α-hydroxylase, 17-20-desmolase, Δ53β- and 3α-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase and 5α- and 5β-reductase. The results suggest that the steroid metabolizing enzyme activities found may reflect a more general ability of early embryonic cells. 相似文献
3.
Uma Raju Susan Kfcdner Mortimer Levitz Alexander Kaganowicz Ancel Blaustein 《Steroids》1981,37(4):399-407
The metabolism of 3H-androsterone was studied in homogenates (fortified with uridine 5'-diphosphoglucuronic acid and andenosine 3'-phosphate 5'-phosphosulfate) of eighteen breast tumors, one muscle underlying the primary breast carcinoma and metastatic axillary lymph nodes from a patient with suspected primary breast cancer. The major metabolites identified were less polar than androsterone. On saponification these lipoidal derivatives afforded androsterone as the only product (3 to 48%). Unmetabolized androsterone and lesser quantities of epiandrosterone, 5α-androstane-3α,17β-diol and 5α-androstane-3,17-dione comprised the free steroid fraction. Androsterone glucosiduronate was isolated (0.17–4.1%) from eight breast tumor homogenates and from the node tissue incubation (17%). There was no apparent correlation between glucuronyltransferase activity and histopathology or estrogen receptor content. 相似文献
4.
A hepatotoxic dose of bromobenzene (3 mmoles/kg) decreases hepatic glutathione concentration in rats by approximately 80% within 5 hr following ip injection. A major bromobenzene metabolite, p-bromophenol at a similar dose did not significantly alter hepatic glutathione levels compared to controls. Twenty four hr after administration, serum glutamate pyruvate transaminase (SGPT) levels were significantly increased by bromobenzene but not by p-bromophenol. After 14C-bromobenzene administration, a significant amount of covalently bound radiolabel was detected in liver, kidney and small intestine. A small amount of covalently bound radiolabel was also detected in the lung. After a similar dose of 14C-bromophenol, covalently bound radiolabel was found in liver (62% of the amount detected with 14C-bromobenzene) and smaller amounts were detected in kidney, small intestine and lung. These data are consistent with the view that the hepatotoxity and glutathione depleting ability of bromobenzene are mediated mainly by bromobenzene-3, 4-oxide rather than by chemically reactive metabolites of p-bromophenol derived from bromobenzene. Covalently bound radiolabel from 14C-bromobenzene, however, may be derived from both bromobenzene-3, 4-oxide and the nontoxic reactive metabolites of p-bromophenol. 相似文献
5.
Nava Zisapel Moshe Laudon 《Biochemical and biophysical research communications》1982,104(4):1610-1616
Microdissected slices of rat hypothalamus were incubated with 3H -dopamine and then subjected to two successive sets of electrical field stimulation in a superfusion chamber. Neurotransmitter release was found to be calcium dependent and the amount of release was determined by scintillation counting of the effluent buffer. The release obtained following the first train of stimuli served as an internal reference. The samples were exposed to drugs during the interval between the two sets of stimuli. Using this technique, as well as K+-evoked depolarization, we were able to show that subnanomolar concentrations of melatonin, the hormone secreted from the pineal gland, inhibits dopamine release from hypothalamic slices. The possibility that melatonin modulates neurotransmission in the brain is therefore indicated. 相似文献
6.
J Diamond R E Ten Eick A J Trapani 《Biochemical and biophysical research communications》1977,79(3):912-918
It has been suggested that increases in cyclic GMP levels are responsible for the negative inotropic effects of acetylcholine in the heart. This hypothesis was tested by monitoring the effects of acetylcholine and sodium nitroprusside on tension and cyclic nucleotide levels in strips of cat atrial appendage. Sodium nitroprusside markedly increased atrial cyclic GMP levels but did not decrease the twitch tension developed by the atrial strips. Low concentrations of acetylcholine, on the other hand, decreased twitch tension without increasing myocardial cyclic GMP levels. No significant change in cyclic AMP levels was observed in any of these experiments. These results are not consistent with the proposed role for cyclic GMP as the mediator of the negative inotropic effects of acetylcholine. 相似文献
7.
The effects of endometrium on metabolism of [3H]-arachidonic acid ([3H]-AA) by bovine blastocysts recovered on day 19 postmating were studied . Blastocysts (n = 12) and endometrial slices were assigned to four incubation groups. In group 1, blastocysts were incubated alone; group 2, endometrial slices were incubated alone; group 3, blastocysts were incubated with endometrial slices; group 4, blastocysts were incubated in 7.5 ml fresh incubation medium plus 7.5 ml frozen-thawed medium from endometrial incubations. In all groups, tissues were incubated in 15 ml modified minimum essential medium (MEM) containing 5 μCi of [3H]-AA and 200 μg radioinert arachidonic acid for 24 h at 37°C in an atmosphere of 50% N2:45% O2:5% CO2. For incubation controls, 5 μCi of [3H]-AA were added to 15 ml MEM and incubated at the same time as tissues from each cow. To evaluate metabolism of [3H]-AA, [3H]-AA and its metabolites were extracted from aliquots of MEM and separated on columns of Sephadex LH-20. Most (78.3 ± 3.2%) of the radioactivity (dpm) in the incubation controls was recovered as [3H]-AA, indicating that there was little breakdown of [3H]-AA in the absence of tissue. Blastocysts produced compounds that migrated with [3H]-13,14-dihydro-15-keto-PGF2α ([2H]-PGFM), [3H]-PGE2 and [3H]-PGF2α. Endometrial slices metabolized very little of the [3H]-AA. Data from groups 1 and 4 were combined (group ) for analysis because the distribution of dpm did not differ between the two groups. In group 3, blastocysts and endometrial slices incubated together tended(P<.10) to produced more [3H]-PGE2 than did group , there tended to be less (P<.10)_[3H]-PGF2α, and there was more (P<.05) [3H]-PGFM than in group . Neither endometrial secretions nor endometrial slices altered the proportion of [3H]-AA metabolized by blastocysts. Endometrial slices appear capable of metabolizing [3H]-PGF2α synthesized by blastocysts, and capable of directing blastocyst metabolism of [3H]-AA away from synthesis of [3H]-PGF2α and toward synthesis of [3H]-PGE2. It is postulated that the endometrium has an important role in regulating the amounts and ratios of prostaglandins in th uterine lumen during early prenancy in cows. 相似文献
8.
The release of endogenous catecholamines (CA) from rat brain slices containing the nucleus tractus solitarius (NTS) was measured using a sensitive radioenzymatic assay. KCl (35 to 75 mM) induced a dose-related increase in norepinephrine (NE) release. Dopamine (DA) release was maximal with 50 mM KCl. An increase in epinephrine (E) release was only observed with 75 mM KCl. NE and E release was totally calcium-dependent whereas DA release was only partially calcium-dependent. Subsequent administrations of KCl released less CA. The calcium dependency of the KCl induced release of E, NE, and DA suggests a neurotransmitter function in the NTS for these CA. A difference in storage sites and/or mechanisms may be responsible for the observed differences in sensitivity to KCl and to extracellular calcium. 相似文献
9.
This case report addresses the occurrence of Brucellosis and its effect on the cattle in developing countries. Three Zebu bulls () are presented and the clinical and pathologic signs are described. Conception rates declined following an abortion storm in one herd and without prior abortions in another herd. Semen collected by electro-ejaculation was found to be azoospermic or with very few spermatozoa. was isolated from seminal vesicles, testes and epididymides. Organs affected and showing microscopic lesions were testes, epididymides and seminal vesicles. The latter were not consistently affected. None of the bulls showed impairment of libido or breeding capacity. 相似文献
10.
Uterine stage embryos collected from the hamster (8-cell) and cow (morula, early blastocyst) were monitored for development (embryo culture) and (embryo transfer) following premature removal of the zona pellucida.Removal of the zona pellucida did not significantly affect development to the blastocyst stage of (1) 8-cell hamster embryos (zonae removed by a combined enzymic-mechanical procedure), (2) bovine morulae (zonae removed by mechanical means only) (3) early bovine blastocysts (zonae removed by the enzymic-mechanical technique).Zona-free hamster embryos formed significantly fewer viable fetuses than did zona-intact embryos. The lower incidence of fetal development observed following transfer of zona-free 8-cell hamster embryos may have resulted in part from the formation of chimeras by fusion of these embryos . Such fusion was observed to occur between zona-free embryos placed in close proximity. The proportion of pregnancies resulting from transfer of bovine blastocysts cultured from zona-free morulae was similar to that of zona-intact embryos.In this study we have demonstrated that (1) enzymic and mechanical procedures used to remove zonae pellucidae from uterine-stage hamster and bovine embryos do not adversely affect subsequent development of these embryos and and (2) zonae pellucidae are not required for normal development of these embryos. These findings have implications for microsurgery of mammalian embryos and for embryo transfer. 相似文献
11.
Guanylate cyclase from crude homogenates of vegetative has been characterized. It has a pH optimum of 8.0, temperature optimum of 25°C and requires 1 mM dithiothreitol for optimal activity. It strongly prefers Mn++ to Mg++ as divalent cation, requires Mn++ in excess of GTP for detectable activity, and is inhibited by high Mn++ concentrations. It has an apparent Km for GTP of approximately 517 μM at 1 mM excess Mn++.The specific activity of guanylate cyclase in vegetative homogenates is 50–80 pmoles cGMP formed/min/mg protein. Most of the vegetative activity is found in the supernatant of a 100,000 x g spin (S100). The enzyme is relatively unstable. It loses 40% of its activity after 3 hours storage on ice. Enzyme activity was measured from cells that had been shaken in phosphate buffer for various times. It was found that the specific activity changed little for at least 8 hours. Cyclic AMP at 10?4 M did not affect the guanylate cyclase activity from crude homogenates of vegetative or 6 hour phosphate-shaken cells. 相似文献
12.
The ability of various prostaglandins (PGs) to affect the anamnestic immune response of keyhole limpet hemocyanin (KLH)-primed rabbit popliteal lymph node cells was investigated. Of the four PGs studied (PGA1, PGE2 and PGF2α), PGE1 was found to have a stimulatory effect, whereas PGA1, PGE2 and PGF2α were ineffective in stimulating or inhibiting the anamnestic response. Under the conditions studied, a 3.5-fold increase in antibody production was obtained in PGE1-treated, KLH-stimulated cultures. Maximum enhancement was obtained when 0.2 μg of PGE1 were added at the time of culture initiation and were allowed to remain in contact with the lymph node cells for 24 hours. 相似文献
13.
Evelyn A. Devine Mary C. Moran Peter J. Jederlinic Anthony J. Mazaitis Henry J. Vogel 《Biochemical and biophysical research communications》1975,67(4):1589-1593
The transducing phage λd, carrying a portion of the chromosome including , is derived from the heat-inducible, lysis-defective strain λy199, which has the and deletions. Cleavage of λy199 DNA by RI endonuclease, followed by agarose slab gel electrophoresis, results in bands corresponding to the known C, D, E, and F segments of λ, and a segment A′ (A plus B minus minus , the cleavage site between A and B being eliminated). Cleavage of λd DNA by RI yields the expected D, E, and F segments of λ and four other segments, termed 14-1 through 14-4, whose length is 17.5, 6.2, 3.0, and 2.0 kilobases, respectively, as determined by electron microscopy and corroborated by electrophoretic mobility. Heteroduplex analysis shows that the cluster is on the 14-1 segment. 相似文献
14.
OKY-1581 is an effective inhibitor of thromboxane synthesis and . The generation of thromboxane B2 (TxB2), prostaglandin E (PGE) and prostaglandin F (PGF) was measured following clotting and during platelet aggregation induced by collagen. The presence of OKY 1581 either or caused a reduction in TxB2 generation during clotting and platelet aggregation with a concomitant increase in PGE and PGF. The effect could be observed two hours after oral or subcutaneous administration of 5 to 100 mg per rabbit and lasted for 24 to 48 hours. The reduction in TxB2 was not accompanied by an inhibition of clotting or platelet aggregation. OKY-1581 appears to be a suitable agent for studying the role of TxB2 in atherosclerosis. 相似文献
15.
Metabolism of radiolabeled arachidonic acid (1AA) by blastocysts and endometrial slices recovered from five gilts 16 days after detection of estrus was studies . Blastocysts from each gilt were divided into four 216 ± 18 mg, and each portion was placed into a separate petri dish containing 15 ml modified minimum essential medium (MEM)_. The incubates from each gilt received either 25, 50, 100 or 200 μg radioinert arachidonic acid (AA). Endometrium was dissected from each uterin horn, sliced and duplicate 509 ± 3 mg portions from each gilt were placed into petri dishes containing 15 ml MEM and 200 μm AA. All incubates received 5 νCi of 1AA (either [14C]-arichidonic acid or [3H]-arichidonic acid). The incubates were rocked at 37°C for 24 h in an atmosphere of 50% n2:45% O2:5% CO2. After incubation, tissues and MEM were separated by centrifugation. Metabolism of 1AA was assessed in extracts of MEM and tissue homogenates by separating 1AA and its metabolites on columns of Sephades LH-20. Blastocysts produced compounds that migrated with [3H]-13,14-dihydro-15-keto-PGF2α (1PGFM), [3H]-PGE2 (1PGE2) and [3H]-PGF2α (1PGF2α). The greatest (P<.05) proportion (35.7 ± 1.8%) of the radioactivity in blastocyst MEM was recovered as PGE2. In blastocyst homogenates, most (66.2 ± 3.3%; P<0.05) of the radioactivity was in a nonporal peak assumed to be arachidonate esters. The concentration of AA ni MEM did not alter metabolism of 1AA by blastocysts. Endometrial slices produced 1PGFM and 1PGE2 but only in small amounts, and they were capable of producing nonpolar, probably esterified, forms of 1AA. It was concluded that porcine blastocysts produced and metabolized prostaglandins and that they make a contribution to the uterine milieu during early pregnancy. 相似文献
16.
Eric E. Bancroft Henry N. Blount Fred M. Hawkridge 《Biochemical and biophysical research communications》1981,101(4):1331-1336
The recently reported method of derivative cyclic voltabsorptometry has been applied to horse heart cytochrome at fluoride doped tin oxide optically transparent electrodes. The advantages of the derivative cyclic voltabsorptometric method compared to voltammetric methods in analytical, kinetic and mechanistic studies are discussed. 相似文献
17.
Daniel H. Riddick Anthony A. Luciano William F. Kusmik Ila A. Maslar 《Life sciences》1978,23(19):1913-1921
Relatively large amounts of immunoreactive prolactin were measured in homogenates of human decidual tissue obtained immediately after delivery of normal term pregnancies. In order to study the release and possible synthesis of prolactin by this tissue, explants of decidua were incubated for 24 hours at 37°C in oxygenated Gey's buffer containing 20% fetal calf serum. When cycloheximide was added to the medium in concentrations sufficient to prevent protein synthesis, 85–90% of the prolactin present in the tissue was released into the medium during the first 3 hours of incubation. No additional prolactin accumulated in either the medium or the tissue during the remainder of the incubation period. In the absence of cycloheximide, the prolactin concentration in the medium increased progressively during incubation, so that after 24 hours the total amount of hormone present in the tissue and medium was significantly greater than that in the tissue and medium prior to incubation (37.6 ± 9.6 ng/ml at 0 time vs 82.2 ± 7.7 ng/ml at 24 hours). When 3H-1-leucine (100 u Ci) was supplied during incubation, radioactive proteins were detected in the medium at 24 hr, 14–20% of which were specifically precipitated by antiserum to human pituitary prolactin. When aliquots of this medium were chromatographed on Sephadex G-100, 80–95% of the 3H-proteins precipitated by antiserum to pituitary prolactin eluted in the same position as did purified, iodinated pituitary prolactin. These data indicate that a species of prolactin which is identical to pituitary prolactin by the criteria of immunoprecipitation and gel chromatography is synthesized by human decidual tissue . 相似文献
18.
Josie M. Nichols G.A.M. Cross 《Biochemical and biophysical research communications》1976,71(3):796-802
Kinetoplast DNA from the order Kinetoplastidae (trypanosomatids) exists as large associations (molecular weight 4 × 1010), made up of about 104 small, probably circular, molecules, commonly known as ‘minicircles’. These minicircles were originally thought to be identical in base composition, suggesting that the coding capacity of kinetoplast DNA is very restricted. However, linear molecules have also been observed in preparations of kinetoplast DNA, which, if they contain unique sequences, could represent additional genetic information. This linear DNA has been assumed to be derived from the kinetoplast, but the possibility of it being nuclear contamination has not been definitely ruled out. Work presented in this paper demonstrates that nuclear DNA contamination may indeed be present in kinetoplast DNA prepared by a commonly used method. 相似文献
19.
Judith A. Richter 《Life sciences》1977,20(4):701-713
The effect of X537A on acetylcholine (ACh) release was examined in superfused slices of rat cerebrum and striatum. The ionophore (30 μM) induced a transient release of ACh which was not dependent on calcium in the medium. Also in contrast to K+-stimulated release, X537A-induced release was not sustained by 10?5M choline in the superfusion medium and not inhibited by 5 × 10?4M pentobarbital. The ionophore did not transport ACh or choline from an aqueous to an organic phase. Both K+ and X537A inhibited 1 μM (3H) choline uptake into striatal synaptosomes but this effect of X537A was more extensive and less reversible than that caused by K+. X537A did not inhibit choline acetyltransferase activity. 相似文献
20.
George M. Stancel Judy S. Ireland Venkat R. Mukku Alice K. Robison 《Life sciences》1980,27(12):1111-1117
The pesticide o,p'-DDT stimulates the production of a specific uterine protein, the so-called induced protein or IP, normally associated with an estrogenic response of the uterus. stimulation of IP production is observed 1 hour after the administration of 250 mg/kg of o,p'-DDT to immature rats. stimulation of IP production is observed after a 1 hour incubation of uteri with 100 μM o,p'-DDT. This response is blocked by Actinomycin D. In contrast to o,p'-DDT, which binds to the cytoplasmic estrogen receptor and stimulates IP production, p,p'-DDT which does not bind well to the estrogen receptor does not stimulate IP production . These findings represent the first report of an estrogenic effect of o,p'-DDT in a completely system. 相似文献