共查询到20条相似文献,搜索用时 9 毫秒
1.
James C. Coffey 《Steroids》1973,22(2):247-257
Tritiated 4-androstene-3,17-dione and testosterone were incubated with submaxillary gland homogenates of 6 month old male mice. In 15 and 180 minute incubations fortified with NADPH, submaxillary tissue converted 4-androstene-3,17-dione predominantly to androsterone and, to a lesser extent, testosterone, 17β-hydroxy-5α-androstan-3-one and 5α-androstane-3α, 17β-diol. Testosterone was converted primarily to 5α-androstane-3α, 17β-diol when exogenous NADPH was available; trace amounts of 4-androstene-3,17-dione, 17β-hydroxy-5α-androstan-3-one and androsterone were also formed. When a NADPH-generating system was omitted from the incubation medium both 4-androstene-3,17-dione and testosterone were poorly metabolized by submaxillary tissue; the amounts of reduced metabolites accumulating were markedly reduced. 相似文献
2.
Peter J. Natale Carrie Ireland John M. Buchanan 《Biochemical and biophysical research communications》1975,66(4):1287-1293
Messenger RNA for two T4 specific enzymes, deoxynucleotide kinase and α glucosyltransferase, have been sized by sedimentation on sucrose density gradients. The sedimentation constants of transferase and kinase mRNAs formed were 21.5S and 14.5S respectively, regardless of the duration of incubation up to 20 min. Although the kinase mRNA isolated from cells infected with T4 phage for 10 min was the same size as found (14.5S), the transferase mRNA was found in a segment approximating the size of the kinase mRNA (14.5S). The experiments indicate that α glucosyltransferase mRNA is formed first as a polycistronic message and is then processed to the smaller unit. 相似文献
3.
Robert A. Schatz Timothy E. Wilens Otto Z. Sellinger 《Biochemical and biophysical research communications》1981,98(4):1097-1107
The administration of adenosine together with homocysteine resulted in a dose-related elevation of cerebral S-adenosyl-L-homocysteine without concomitant perturbation of S-adenosyl-L-methionine levels. The adenosine + homocysteine treatment also decreased the incorporation of labile and stable methyl groups into brain proteins. Brain [3H]-phosphatidyl N,N-dimethylethanolamine and [3H]-phosphatidylcholine were also significantly decreased while [3H]-phosphatidyl-N-monomethylethanolamine remained unchanged. The data indicate that elevated brain S-adenosylhomocysteine can markedly and selectively inhibit the methylation of brain proteins and phospholipids. 相似文献
4.
E.A. Hosein M. Lapalme E.B. Vadas 《Biochemical and biophysical research communications》1977,78(1):194-201
Differential scanning calorimetry of crude brain mitochondrial lipids obtained from control and morphine treated rats was carried out and the lipid phase transition measured. Morphine treatment resulted in a significant decrease in the temperature range and enthalpy of the phase transition. This effect was found to be dose dependent and reversible both and by naloxone. Studies with levorphanol and dextrorphan demonstrated stereospecificity. Furthermore, the ether precipitable fraction of total lipid extracts was shown to mediate the opiate response. 相似文献
5.
André Dupont Lionel Cusan Marie Garon Gabriel Alvarado-Urbina Fernand Labrie 《Life sciences》1977,21(7):907-914
Thirty sec after the intrajugular injection of [3H] methionine-enkephalin (met-enkephalin) in the rat, the radioactivity was already distributed in an apparent volume of 53 ml and the metabolic clearance rate calculated from the characteristics of the plasma disappearance curve was 10 ml/min. As shown by partition chromatography plasma extracts obtained 15 sec after injection of [3H] met-enkephalin, only 5% of the total radioactivity migrated as the intact pentapeptide, while no detectable intact pentapeptide remained 2 min after injection, thus indicating a half-life of [3H] met-enkephalin of the order of 2 to 4 sec. Incubation of rat cerebral tissue with [3H] met-enkephalin indicates that the first step in the breakdown of met-enkephalin in both plasma and brain tissue is cleavage of the Tyr-Gly amide bond. These data offer an explanation for the low activity of met-enkephalin after intraventricular or intravenous administration. 相似文献
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Robert R. Rando F.W. Bangerter 《Biochemical and biophysical research communications》1977,76(4):1276-1281
The naturally occurring amino acid gabaculine ((?)-5-amino-1,3 cyclohexadiene carboxylic acid) is a potent irreversible inhibitor of mouse brain γ-aminobutyric acid (GABA)-α-ketoglutaric acid transaminase. When administered I.P. gabaculine, irreversibly inhibits the mouse brain enzyme in a time dependent fashion. Concomitant with this inhibition is a rise in endogenous brain GABA levels. Administration of gabaculine at a concentration of 100 mg/kg mouse leads to the complete inhibition of the enzyme after 4 hrs. Brain levels of GABA continually rise after the administration of the drug. After 20 hrs they are 15–20 times higher than levels in the untreated animals. 相似文献
8.
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
9.
The specific synthesis of F mRNA directed by the F gene carried on the specialized transducing bacteriophage F, performed , is described with the use of an S180 extract from a strain carrying R?. Synthesis of F mRNA is biphasic at approximately 7 minutes. The regulation of F mRNA synthesis by the specific arginine holorepressor present in an S180 extract prepared from a strain carrying the R+ allele is described. 相似文献
10.
R.M. Sharpe D.G. Doogan I. Cooper 《Biochemical and biophysical research communications》1982,106(4):1210-1217
Injection of a luteinizing hormone-releasing hormone (LHRH) agonist into 55-day-old male rats which had been hypophysectomized 3 days earlier resulted in a 10- to 30-fold increase in the levels of testosterone in serum and testicular interstitial fluid (IF) in the 4h following injection. The levels achieved were within or above the normal range for intact untreated rats of this age. In similar animals, injection of LHRH agonist also enhanced the serum testosterone response to injected hCG at , but not at later times after injection, and by 24h reduced IF levels of testosterone suggested that LHRH agonist had begun to inhibit stimulation by hCG. , dispersed Leydig cells from untreated hypophysectomized rats showed a 2-fold increase in testosterone responsiveness to LHRH agonist when compared to cells from intact rats, and this change was associated with an 80% increase in the number of Leydig cell LHRH-receptors. 相似文献
11.
D.H. Coy F.Labrie.M. Savary E.J. Coy A.V. Schally 《Biochemical and biophysical research communications》1975,67(2):576-582
The LH-releasing activity of eight superactive analogs of LH-RH was measured in pituitary cells in primary culture. Introduction of the C-terminal ethylamide modification into [D-Ala6]- and [D-Leu6]-LH-RH (two peptides already 3 times more active than LH-RH) increases their activities 10-fold. [D-Phe6]- and [D-Trp6]-LH-RH are 90 and 100 times more active than LH-RH, respectively. The ethylamide derivatives of these two compounds are however approximately six times less active than the parent peptides. 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.
G. Brunet S. Charleson A.W. Ford-Hutchinson 《Prostaglandins & other lipid mediators》1985,29(6):921-932
Chopped lung from inbred hyperreactive rats was challenged with antigen following active on passive sensitization and supernatants were assayed for the presence of leukotrienes (LTs) by radioimmunoassay. Dose-related increases in the release of LTC4- and LTB4-immunoreactive material were obtained with significantly more material being released following passive sensitization. Chromatographic analysis indicated the presence of LTB4, LTC4 and LTE4. When LT release inbredred rats was compared to Sprague-Dawley or Fischer rats, the amounts released were as follows: Inbred > Sprague-Dawley > Fischer. It was concluded that the release of LTs in the three strains correlated with the degree of non-specific bronchial hyperreactivity. 相似文献
14.
Prostaglandin synthesis in rat embryo tissue: The effect of non-steroidal anti-inflammatory drug and
Kenneth L. Klein Kenneth E. Clark William J. Scott 《Prostaglandins & other lipid mediators》1984,27(5):659-672
Aspirin and salicylate are well-known but poorly understood teratogens in laboratory animals. Because aspirin inhibits PG synthesis, we systematically examined PG synthesis in rat embryo homogenates, the inhibition of PG synthesis and by various non-steroidal anti-inflammatory drugs, and tested the hypothesis that the inhibition of PG synthesis is responsible for aspirin-induced limb defects in rats. We report that embryonic rat homogenates synthesis 6-keto-PGF1α, PGE, and PGF in large amounts from endogenous substrate, that aspirin and other non-steroidal anti-inflammatory drugs inhibit PG synthesis but not necessarily , and that contrary to our original hypothesis, the inhibition of PG synthesis is likely not responsible for aspirin-induced limb defects in rats. 相似文献
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16.
Metoclopramide, a potent antagonist to apomorphine, was used to the rats to determine its effect on the release of prolactin. A single i.p. injection of metoclopramide at 10 or 100 μg/100 g b.w. under urethane anesthesia increased serum prolactin levels by 1.6 or 7.2 fold, respectively, compared with basa levels. This prolactin increase was completely abolished by 2-bromo-α-ergocryptine (CB-154).These data suggest that metoclopramide stimulates prolactin secretion in rat and this secretion is abolished by dopaminergic stimulant. 相似文献
17.
In the mixed venous blood of anaesthetized, heparinized cats prostacyclin de-aggregated platelet thrombi, which were formed on the surface of blood-superfused collagen strips or on the surface of blood-superfused aortic strips from atherosclerotic rabbits. The reversal of platelet aggregation by prostacyclin was still achieved 3 hrs after the formation of platelet clumps. After an intravenous injection of prostacyclin the ID50 for its de-aggregatory action was 7.5 μg/kg. Theophylline ethyldiamine (aminophylline), at a dose of 3 mg/kg i.v., did not reverse platelet aggregation but it enhanced the duration of the de-aggregatory action of prostacyclin; it had little effect on the hypotensive action of prostacyclin. It is concluded that prostacyclin disintegrates platelet clumps long after they are formed in heparinized blood and that its anti-platelet action, but not hypotensive action, is selectively potentiated by a phosphodiesterase inhibitor. The above experimental data indicate the possibility of the combined use of theophylline and prostacyclin in arterial thrombosis. 相似文献
18.
Sandra S. Ristow Jean R. Starkey G.Michael Hass 《Biochemical and biophysical research communications》1982,105(4):1315-1321
The effect of the addition of small quantities of alcohols to cocultures of natural killer effector cells from mice and BDIX rats with YAC-1 tumor cell targets has been studied. The order of inhibition of NK cell-mediated killing is 1-butanol > 1-propanol > 2-propanol > ethanol > methanol. The inhibition of killing due to the addition of alcohol correlates with decreases of effector-target cell binding. Therefore caution should be exercised in interpreting results of cellular experiments in which these alcohols have been used to solubilize inhibitors. 相似文献
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20.
Andreas Gescher Maurizio DIncalci Roberto Fanelli Pierluigi Farina 《Life sciences》1980,26(2):147-154
N-Hydroxymethylpentamethylmelamine (HMPMM) was identified by HPLC and by GLC-MS after derivatization, as a metabolite of the anticancer drug hexamethylmelamine (HMM) in incubation mixtures with fortified mouse liver 9000 × g and microsomal preparations. HMPMM formation was dependent on the presence of NADPH and oxygen. N-demethylated metabolites were also found. HMPMM displays appreciable chemical stability and 29% was recovered after 60 min incubation in buffer. HMPMM constituted more than 50% of total HMM metabolites in 30 min incubations. The known chemical reactivity of carbinolamines means that HMPMM could be involved in the pharmacological or toxic effects of HMM. 相似文献