摘要:

This study was designed to confirm the identity of the enzyme involved in the appearance of a nuclear metabolite of 6a—methyl progesterone (6MP) in mouse kidney but not in prostate-seminal vesicle. 6MP and progesterone competed for metabolism by the kidney enzyme. Using progesterone as substrate, the results of recrystallization of the product with 20a-hydroxy progesterone supported the identification of the enzyme as 20a-hydroxysteroid dehydrogenase (20aHSD). The enzyme had a substrate specificity similar to that reported for 20aHSD in other tissues. Renal enzyme activity was higher in female than in male CD-1 mice while activity was generally lower and without a sex difference in a random bred colony. Renal enzyme activity varied slightly with the estrous cycle, being highest at proestrus and lowest on day 2 of diestrus. Little enzyme activity was detected in prostate-seminal vesicles. It appears that 20aHSD is an important factor in regulating the differential presence of the 20a-metabolite of 6MP in kidney and prostate-seminal vesicle nuclei.

ISSN:0743-5800    

DOI:10.1080/07435808709023658

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Using partially purified trypsin-solubilized porcine thyroid peroxidase (TPO), an antiserum was developed which inhibited enzyme activity in vitro, and which cross-reacted with partially purified rat TPO. Using rat thyroid minces, this antiserum was utilized to detect radiolabeled TPO in vitro. Newly synthesized rat TPO was observed in the presence of TSH (10 mU/ml), an effect which was completely blocked by co-incubation with cycloheximide. TPO biosynthesis was detected within 6 h of incubation, consistent within a rapid effect of TSH on thyroidal protein biosynthesis.

ISSN:0743-5800    

DOI:10.1080/07435808709023659

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Circulating testosterone levels have generally been reported to increase during short term, intense running or bicycle ergometer exercise. Swimming differs from such activity because of the strenuous arm activity and because it is conducted in a liquid medium in the horizontal position with the weight totally supported. To investigate whether such differences modify the serum testosterone response to exercise, we measured serum testosterone levels before and after a maximal intensity swimming test in ten elite male and ten elite female swimmers. Levels of circulating testosterone fell in 19 of 20 swimmers in contrast to previous reports of exercise in the vertical position. In women mean testosterone levels declined by 39.4% from baseline values and in males, mean testosterone levels declined by 19.0%. Since the incremental protocol was similar to in design to maximal intensity tests conducted on a treadmill or bicycle ergometer, these data suggest that the differing physical circumstances of swimming lead to a qualitatively different testosterone reponse to exercise.

ISSN:0743-5800    

DOI:10.1080/07435808709023660

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

A single injection of either 5 or 10 mg/kg 8-methoxypsoralen (8-MOP) was given intraperitoneally to male rats at the end of the 14 h light phase (at 2000 h). Two h later (at 2200 h), when the normal nocturnal surge of N-acetyltransferase (NAT) activity and melatonin content in the pineal gland had begun in vehicle-injected controls, mean pineal NAT after the 10 mg/kg 8-MOP was 1.8-fold higher than that after vehicle, though pineal melatonin content did not differ between vehicle- and drug-injected rats. By 4 h into the dark period (at 2400 h), the NAT activity in both 8-MOP injected groups of rats was greater than that in vehicle treated animals; again, however, 8-MOP treatment did not influence the pineal melatonin content. At 0200 h (6 h into the dark period), the difference between the NAT activity in pineals of rats treated with 5 mg/kg 8-MOP and the vehicle was not statistically significant, but the animals that received 10 mg/kg drug still had statistically elevated levels of the serotonin acetylating enzyme. At 0200 h the pineal melatonin levels were equivalent among the three treatment groups. Rats given 5mg/kg 8-MOP always had NAT values intermediate between those of rats injected with vehicle and those that received 10 mg/kg 8-MOP suggesting that the NAT response to the drug was dose related. These results show that the pineal response to psoralen involves an elevation of NAT activity without a commensurate change in the melatonin content of the gland.

ISSN:0743-5800    

DOI:10.1080/07435808709023661

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Chloroquine increased the binding of125I-labeled insulin to rat hepatoma cells (R-Y121B) at 4°C. The effect of chloroquine on insulin binding was amplified at 23°C, and a large increase in cell-associated radioactivity was observed. Scatchard analysis showed that chloroquine increased the affinity of insulin for cells at both 4°C and 23°C, and that this increase eventually caused the accumulation of insulin internalized by cells at 23°C.

ISSN:0743-5800    

DOI:10.1080/07435808709023662

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Effects of 3,3′,5-triiodo-L-thyronine (T3) and dexamethasone (Dex) on the abundance of proteins resolvable by two-dimensional gel electrophoresis were examined in cultured human skin fibroblasts. Confluent cultures were incubated in medium supplemented with thyroidectomized calf serum and were treated with either T3(100 nM), Dex (100 nM) or both hormones for 2 days and then labelled with [3] leucine for 1 day. Most of the>100 resolvable radiolabelled proteins were unaffected by hormone treatment. However, both hormones could increase or decrease the abundance of a limited number (∼10) of specific proteins. Some of these affected proteins appear to be coregulated. This result is consistent with effects demonstrated previously in pituitary adenoma cultures and suggests that both hormones regulate protein metabolism in human fibroblasts. This may be an ideal model for studying the nature of resistance to thyroid and glucocorticoid hormones.

ISSN:0743-5800    

DOI:10.1080/07435808709023663

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Available androgen binding to soluble proteins from the cytosol of human endometrium was studied using the dextran coated charcoal adsorption method and sucrose density centrifugation analysis. Specific binding of [3H]-5α-dihydrotestosterone ([3H]-DHT) was observed with both methods. The apparent dissociation constant (Kα), for DHT binding is 1.3×0.2 (SEM) nM and the binding capacity 177×42 (SEM) fmol/mg protein. Sucrose density ultracentrifugation identifies specific [3H]-DHT binding that sediments at 4S and 8S. The stability of the androgen receptor in human endometrium is increased by the addition of 10% glycerol to the homogenization buffer. The addition of trypsin or pronase and heating at 60°C reduces specific binding which demonstrates that the specific [3H]-DHT binder is a protein. The uptake of [3H] DHT in endometrial tissue minces indicated that 20% of the bound radioactivity was nuclear. Steroid specificity suggests that the binding protein from the uterus is specific for androgens. These observations indicate that androgen binding protein in the human uterus has the characteristics of the androgen receptor.

ISSN:0743-5800    

DOI:10.1080/07435808709023664

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

We examined the ability of four commonly used culture media to support prolactin (PRL), growth hormone (GH), and adrenocorticotropic hormone (ACTH) release, as well as the inhibitory PRL response to dopamine. After a week of primary culture, rat anterior pituitary cells from both genders were studied over a 4 hour period. Whereas ACTH secretion was similar across the various media, PRL and GH release were lessened with M199 and F10, respectively. Dopamine inhibited PRL release under all media conditions which was inconsistant with the reported lack of a dopamine effect with RPMI-1640 medium. These data confirm the postulate that media culture conditions can determine the degree of expression of constituitive phenotypes in anterior pituitary cells.

ISSN:0743-5800    

DOI:10.1080/07435808709023665

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0743-5800    

DOI:10.3109/07435808709023666

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor