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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Only 35-50% of the label accumulated after incubation of cultured Sertoli cells with 3H-testosterone was readily extractable with 0.4 M KCl during a 1 h exposure. The degree of extractability was relatively constant over the pH range 7.0-8.5 but could be increased by prolonged (15 h) exposure. While 0.1 M KCl extracted a measurable amount of label, 0.4 M KCl was significantly more efficient. Furthermore, a higher proportion of the material extracted with 0.4 M KCl was associated with macromolecular species. After a 45 min exposure to 3H-testosterone, the nuclear fraction contained primarily labeled testosterone and its 5 alpha-reduced metabolites. The relative distribution of these metabolites between salt-resistant and readily extractable forms varied between experiments. In contrast, 3H-R1881 (17 beta-hydroxy-17-methylestra-4,9,11-trien-3-one) remained essentially intact in the nuclear fraction but also was only 35% extractable with 0.4 M KCl. In conclusion, although the quantitative aspects of salt extractability appear to depend to some extent upon the extraction conditions, it is apparent that the Sertoli cell nuclear fraction accumulates a significant amount of androgen in a form which is relatively resistant to removal with 0.4 M KCl. The biological significance of this phenomenon remains to be established.
Steroids 1979 Oct
PMID:Effect of ionic strength on the interaction of androgens with Sertoli cell nuclei. 4 73

The urinary excretion of 3beta,16beta-dihydroxy-5-androsten-17-one (16beta-OH-DHEA) is increased in patients with low renin essential hypertension. This steroid and its isomer 3beta,17beta-dihydroxy-5-androsten-16-one (16-oxo-A) have also been reported to have mineralocorticoid activity in adrenalectomized rats. These findings have led to the postulate that excessive secretion of 16beta-OH-DHEA may be responsible for the production of low renin essential hypertension. In this study unilaterally nephrectomized salt loaded rats injected once a week with 30 mg of 11-desoxycorticosterone acetate per/kg of body weight for 2 month periods developed hypertension. Rats given similar amounts of 16beta-OH-DHEA or 16-oxo-A and rats given no steroids did not develop hypertension. We conclude that it is unlikely that 16beta-OH-DHEA and 16-oxo-A are direct causative factors in the production of low renin essential hypertension.
Steroids 1977 Jan
PMID:Blood pressure changes following chronic administration to rats of 3beta,16beta-dihydroxy-5-androsten-17-one, 3beta,17beta-dihydroxy-5-androsten-16-one and 21-hydroxy-4-pregnene-3,20-dione-21-acetate. 13 80

Addition of soluble supernatant to testis microsomes results in 42% increase in steroid 17,20-lyase activity and a 65% increase in 17alpha-hydroxylase activity. This stimulatory activity could be partially purified by salt fractionation. The activating factor(s) was not removed by dialysis nor did it appear to be lipid. It was destroyed by trypsin. Differential effects of heat were observed with the hydroxylase and lyase activators. The activation did not affect Km but only increased Vmax. The supernatant could be added to each enzyme to the point of maturation. No binding of steroids by the supernatant could be detected. Corpus luteum and placental supernatant did not stimulate enzymic activity, but supernatant from an adrenal adenoma was active.
Steroids 1978 Oct
PMID:Stimulatory effect of soluble supernatant on hydroxylase activity of rat testis microsomes. 30 70

The 7- and 12-monosulfates of chenodeoxycholic acid, deoxycholic acid, and cholic acid were prepared by sulfation of the protected bile acids with sulfur trioxide-triethylamine in pyridine overnight and were isolated by precipitation as the p-toluidinium salt after removing the protecting group(s). The taurine conjugates were obtained by conjugating the bile acid sulfates with taurine in hot dimethylformamide (DMF) in the presence of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ). A new procedure of preparing glycine conjugated bile acid sulfates by direct conjugation of the bile acid sulfate triethylammonium salt with ethyl glycinate in boiling chloroform in the presence of EEDQ is also described. The advantage of these procedures over other procedures are their simplicity and their higher yields (tyically above 90%) The thin layer chromatographic mobilities of these sulfates are presented. The influence of side chain and hydroxyl group configurations on the properties of bile acid sulfates is briefly discussed.
Steroids 1979 Feb
PMID:Bile acid sulfates. III. Synthesis of 7- and 12-monosulfates of bile acids and their conjugates using a sulfur trioxide-triethylamine complex. 46 91

The isomeric monosulfates of chenodeoxycholate, deoxycholate, and their taurine or glycine conjugates, were synthesized and characterized. Reaction with chlorosulfonic acid in pyridine for 2 minutes mainly afforded the 3-monosulfates. To prepare the 7- or the 12-monosulfates, the 3-hydroxyl group was protected by carbethoxylation prior to sulfation of the 7- or 12-hydroxyl group for 24 h to 5 days; after sulfation, the protecting 3-carbethoxy function was removed by mild alkaline hydrolysis. The crude bile salt monosulfates were purified by chromatography on silica gel and on Sephadex LH-20 and were crystallized from methanolethanol-ethyl acetate. The results of elemental analysis demonstrated that the compounds were disodium dihydroxy bile salt monosulfates. Thin layer chromatography of the sulfates, and gas-liquid chromatography after oxidation and solvolysis, showed that the substances were pure and that the sulfate group was at the expected position.
Steroids 1977 Nov
PMID:Synthesis and characteristics of the specific monosulfates of chenodeoxycholate, deoxycholate and their taurine or glycine conjugates. 61 27

A nuclear exchange assay was developed for brain estrogen receptors. The assay employs an extraction procedure which solubilizes essentially all of the estradiol from brain cell nuclei: purified cell nuclei are evenly dispersed in a hypotonic buffer prior to the addition of an equal volume of 0.8M KC1. Experiments with an in vivo injection of 3H-estradiol established that this procedure extracts even normally salt-resistant binding. For exchange, aliquots of the extract are incubated with 3H-estradiol or 3h-estradiol plus 100-fold excess unlabeled estradiol. Bound 3H-estradiol is separated from free 3H-estradiol on Sephdex LH-20 columns. Loss of estradiol binding activity can occur with brain nuclear extracts under conditions required for exchange. This loss of binding is inhibited by the addition of bacitracin to the incubation buffer. The exchange is complete within 5 hrs at 25 degrees C and specific binding activity is stable for at least 16 hrs. The assay was validated by comparing levels of macromolecular-bound radioactivity after an in vivo injection of 3H-estradiol and levels determined by exchange after an injection of unlabeled estradiol. Scatchard analysis confirmed the high affinity nature of the binding measured by exchange.
Steroids 1977 Nov
PMID:An exchange assay for estrogen receptors in cell nuclei of the adult rat brain. 61 33

The binding in vitro of tritiated aldosterone to domestic duck (Anas platyrhynchos) kidney tissue has been investigated. Using tissue from animals on a normal diet, tritiated aldosterone was specifically bound to kidney cytosol with an apparent equilibrium dissociation constant of about 9 nM and number of binding sites in the 20 fmol/mg protein range. These values did not show statistically significant changes when the cytosol originated from animals with salt activated nasal glands. Kidney cytosols labeled with tritiated aldosterone sedimented with a single peak at 8S in a linear sucrose gradient (10--30%) and this peak was quenched by excess, radioinert aldosterone. Following incubation of labeled cytosols with crude nuclei, the cytosols became depleted of the label and aldosterone was translocated to the Tris-soluble and Tris-insoluble, 0.4 M KC1 soluble nuclear fractions. Kidney cytosols metabolized aldosterone extensively to a compound presumed to be 3alpha,5beta-tetrahydroaldosterone. However, only unchanged aldosterone became receptor-bound. It was concluded that the duck kidney possesses aldosterone receptors, though competition studies indicated that the specificity of these receptors might be different from those described in the mammalian kidney.
Steroids
PMID:Corticosteroid receptors in the avian kidney. 70 13

The effects of cholecystectomy upon bile salt kinetics were studied in normal guinea pigs. After cholecystectomy, bile salt pool size decreased, fractional daily turnover rate increased, and the rate of bile salt synthesis was unchanged. These data indicate that an increased frequency of bile salt enterohepatic cycling is sufficient to produce alterations in bile salt kinetics. Abnormalities of bile salt synthesis need not be present in order for a reduction in pool size to occur.
Steroids 1978 Sep
PMID:Effects of cholecystectomy upon bile salt kinetics in the guinea pig. 71 17

Comparative studies of the effects of fasting on the total bile salt pool sizes of intact and cholecystectomized hamsters and rats were made. Rats, a species which has no gallbladder, are able to maintain the size of their total bile salt pool during 24, 48 and 72 hour fasts by an undetermined effective mechanism. Intact hamsters fasted 24, 48 and 72 hrs maintained and even increased the size of their bile salt pool. Bile salt conservation was effected by storage of the salts in the gallbladder, and to some extent, the small intestine. Cholecystectomized hamsters apparently lack any mechanism to effect bile salt conservation during fasting since their bile salt pool size decreased precipitously during 24 and 48 hr fasts.
Steroids 1977 May
PMID:Comparative studies of the effects of fasting on bile salt pool sizes of hamsters and rats. 89 35

Since there is a much longer uterine nuclear retention of the U-11, 100A (antiestrogen) receptor complex (UARC) than of the estradiol receptor complex (ERC) at 4-12 hrs after injection, experiments were designed to determine if there is a difference between the relative nuclear affinities for the two RCs as determined by extraction with various ionic strength mediums. Although the UARC was retained longer in the nuclear fraction in vivo, the UARC was completely extractable with 0.3M KCl or 50mM spermine, whereas the ERC demonstrates a salt-resistant form. This suggests that the ERC is more tightly bound to nuclear components through this salt-resistant form of the receptor. In addition, various intercalating agents were used to distinguish the different nuclear chromatin DNA sites where the UARC and ERC may be binding. With actinomycin D (50 uM) more ERC than UARC was retained in the nuclear fraction. However, with ethidium bromide (100uM) less ERC than UARC was retained. Also, the ERC selectively released by ethidium bromide is precisely that fraction not released by salt. These results indicate that the UARC and ERC bind to different chromatin loci.
Steroids 1976 Aug
PMID:Antiestrogen action: differential nuclear retention and extractability of the estrogen receptor. 97 36


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