Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The metabolism of 7alpha-3H-dehydroepiandrosterone was studied in six human breast carcinomas in vitro. All mammary tumors transformed DHA to testosterone, dihydrotestosterone, 5alpha-androstane-3alpha, 17beta-diol and 5alpha-androstane-3,17-dione. Of the tumors investigated, three estrogen receptor-negative tumors converted DHA to estradiol and only one estrogen receptor-positive tumor produced estradiol from DHA. Observations on the relationship of androgen metabolism and hormone dependency are discussed.
Steroids 1975 Oct
PMID:Metabolism of dehydroepiandrosterone by hormone dependent and hormone independent human breast carcinoma. 17 46

Tritiated 4-androstene-3,17-dione and testosterone were incubated with submaxillary gland homogenates of male and female rats. The metabolism was predominately reductive. In 15 and 180 min incubations submaxillary tissue converted 4-androstene-3,17-dione chiefly to androsterone. Less testosterone, 17 beta-hydroxy-5 alpha-androstan-3-one, 5 alpha-androstane-3,17-dione, 5 alpha-androstane-3 alpha, 17 beta-diol, and 4-androstene-3 alpha, 17 beta-diol were also identified. Testosterone was converted to the same products plus 4-androstene-3,17-dione. 5 alpha-Androstane-3 alpha, 17 beta-diol was the major testosterone metabolite. Qualitatively the metabolism by male and female submaxillary gland was similar.
Steroids 1979 Feb
PMID:In vitro metabolism of 4-androstene-3,17-dione and testosterone by rat submaxillary gland. 46 93

4beta,5-Epoxy-5beta-androstane-3,17-dione (1a), 17beta-hydroxy-4beta,5-epoxy-5beta-androstan-3-one (1b) and 17beta-acetoxy-4beta,5-epoxy-5beta-androstan-3-one (1c) were treated with anhydrous hydrogen fluoride in pyridine (70% solution) at 55 detrees and yielded the corresponding 4-en-4-ols, e.g. 4-hydroxy-4-androstene-3,17-dione (2a). As the reaction temperature was lowered each epoxide formed a second product which, at -75 degrees, was the major component of the reaction mixture and was identified as the 5alpha-fluoro-4alpha-ol derivative of the parent enone, e.g. 4alpha-hydroxy-5-fluoro-5alpha-androstane-3,17-dione (3a). These fluorohydrins are thermally unstable, losing hydrogen fluoride. The acetates of -he fluorohydrins were also prepared, characterized, and shown to be more stable than the parent alcohols.
Steroids 1978 Jan
PMID:Reactions of 4beta,5-epoxy-5beta-androstan-3-ones with hydrogen fluoride in pyridine. 66 57

The metabolism of 1,2-3H-androstenedione was studied in 2 cell lines, MCF-7 (estrogen responsive) and BT-20 (estrogen nonresponsive) over 48 hrs. Water soluble and unconjugated metabolites were separated by solvent partition and the former was submitted to chromatography on Sephadex LH-20 and enzyme hydrolysis. The resulting unconjugated steroids were separated by paper chromatography and identities were established by reverse isotope dilution. The unconjugated steroids initially obtained were separated by chromatography and identified by reverse isotope dilution. About 70% of the androstenedione was metabolized by both cell lines. However, the respective conversions to conjugates by MCF-7 and BT-20 were 31% and 0.32%. In the former, glucosiduronates predominated (94%) and consisted of androsterone (55%), etiocholanolone (9.4%) and androstanediol (5alpha-androstane-3alpha,17beta-diol) (9.3%). Androsterone comprised most of the unconjugated metabolites in both cell lines. Androstanediol was found in both cell lines, 2% in MCF-7 and 12% in BT-20. Testosterone, 5alpha-androstane-3,17-dione and 3beta-hydroxy-5alpha-androstan-17-one were isolated only from MCF-7. The metabolism of 3H-estriol was studied in a similar way. Both cell lines produced about equal amounts of estriol-3-sulfate (9%) and a compound with properties of estriol-3-glucosiduronate (0.15--0.5%). The results worthy of emphasis are: 1. The far greater conjugation of androgens exhibited by the MCF-7 cell lines as compared to the BT-20 cell lines; 2. In MCF-7, the high conversion of androstenedione to etiocholanolone (glucosiduronate form), a metabolite reported to form only in liver and sebaceous cysts; 3. The possible formation in both cell lines of estriol-3-glucosiduronate, normally a metabolite of the intestine.
Steroids 1978 Dec
PMID:Steroid metabolism in human breast cancer cell lines. 73 1

A radioimmunoassay using an antiserum produced against 6beta-hydroxy-4-androstene-3,17-dione-6-succinyl-BSA conjugate is described which permits the rapid determination of 4-androstene-3,17-dione in multiple serum samples that are purified by column chromatography on neutral alumina. Steroids which reacted significantly with the antiserum were found to be 5alpha-androstane-3,17-dione, 5beta-androstane-3,17-dione, and 6beta-hydroxy-4-androstene-3,17-dione. After column chromatography on alumina, however, the only significantly cross-reacting steroids were the 5alpha and 5beta-androstane-3,17-diones, while cross-reactivity from other steroids was reduced to less than 1%.
Steroids 1977 Jun
PMID:An improved radioimmunoassay for 4-androstene-3,17-dione. 91 Feb 47

Testosterone, 4-androstene-3,17-dione, 19-hydroxy-4-androstene-3,17-dione, 4alpha-5-oxido-5alpha-androstane-3,17-dione and 4beta-5-oxido-5beta-androstane-3,17-dione were compared as substrates for aromatization by the small particle fraction from sow ovaries. Relative conversion rates were: 19-hydroxy-4-androstene-3,17-dione:4-androstene-3,17-dione: testosterone: 4alpha-5-oxido-5alpha- and 4beta-5-oxido-5beta-androstane-3,17-dione; 100:32:20:congruent to O. Apparent Michaelis constants were 4.4 muM for 4-androstene-3,17-dione and 12 muM for testosterone. Maximum velocities were 0.20 pmoles/mg protein per min for androstenedione [1] and 0.16 for testosterone. The substrate preferences of the aromatizing system found in ovary are similar to those of the enzyme found in placenta.
Steroids 1976 Aug
PMID:Steroid aromatization by a small particle fraction from porcine ovaries. 97 38

Neural tissues from adult, castrated male guinea pigs were examined for their capability to concentrate and metabolize [1,2-3H]testosterone (T) and [1,2-3H]dihydrotestosterone (DHT), both in vitro and in vivo. In vitro uptake of DHT and T was greater in the hypothalamus and anterior pituitary than in the cerebral cortex. With DHT as the substrate, the 800 times g particulate concentration of this compound was highest in the hypothalamus, although in this tissue, particulate concentration was less than that of the cytoplasm. In the cerebral cortex 5alpha-androstane-3,17-dione was the most abundant metabolite, whereas 5alpha-androstane-3,17-dione, 5alpha-androstane-3alpha,17beta-diol, and 5alpha-androstane-3beta,17beta-diol were all present in equivalent amounts in the hypothalamus and pituitary. Incubation with T resulted in the formation of DHT, 4-androstene-3,17-dione, and a compound with the mobility of 5alpha-(or 5beta-)androstane-3,17-dione. The radioactivity associated with DHT was the most prevalent in the pituitary (1.3%), and least prevalent in the cerebral cortex (0.6%), and in all cases cytoplasmic concentration of this compound exceeded the concentration in the particulate fraction. Recrystallization failed to confirm the presence of estradiol-17beta. Although there were no apparent tissue differences in the uptake of DHT or T 1 hour after their injection, intracellular distribution varied. In all tissues examined, that percentage of total radioactivity attributable to DHT was greatest in the 800 times g particulate preparations, particularly in the hypothalamus. Thus neural tissues in the guinea pig, as in other species, exhibit differential uptake and metabolism of androgen through which physiological and behavioral effects may be mediated.
Steroids 1975 Feb
PMID:Neural uptake and metabolism of testosterone and dihydrotestosterone in the guinea pig. 111 64

Steroids inhibit the exchange transport of glucose in human erythrocytes. The extent of inhibition is roughly correlated to the affinity of the steroids to the membrane lipids. All C-21-steroids tested show a competitive inhibition while the C-19-steriods show different types of inhibition. 5Beta-androstane-3,17-dione acts as a competitive inhibitor. The inhibition by testosterone is of mixed type, while with androst-4-ene-3,17-dione and 5alpha-androstane-3,17-dione a non-competitive inhibition is observed. In this case two inhibitor molecules can be bound per transport molecule. The "non-competitive" inhibitors compete also to some extent with the glucose binding. This effect, however, is at high inhibitor concentrations masked by the more powerful non-competitive inhibition. Competitive and non-competitive inhibitors compete with each other. The structural requirements for the different types of inhibition are discussed.
 ...
PMID:Interaction of steroids with the transport system of glucose in human erythrocytes. 120 39

The synthesis of 11-oxatestosterone from 11-oxa-5 alpha-androstane-3,17-dione, which is available from hecogenin, is described. The product shows, in comparison with the natural hormone, diminished androgenic and anabolic activities.
Steroids
PMID:Steroids and related products. LIV. The synthesis of 11-oxa steroids. VI. The synthesis of 11-oxatestosterone. 366 Apr 39

Interstitial cells derived from intact immature rats were cultured as monolayers. Their response to gonadotropins was evaluated by radioimmunoassay of 3',5'-cyclic AMP and steroids in the medium. Steroids were measured either directly (testosterone and progesterone) or after previous oxidation and thin layer chromatographic purification of the steroid extracts (4-androstene-3,17-dione, 5 alpha-androstane-3,17-dione, progesterone, 5 alpha-pregnane-3,20-dione). It could be demonstrated that these cells respond to gonadotropins with increased secretion of C19- and C21-steroids for at least 10 days. The total amount of steroids secreted in the medium, however, decreases markedly. During the first days of culture C19-steroid production falls dramatically whereas the secretion of C21 derivatives increases. A major fraction of the extracted steroids has undergone 5 alpha-reduction. A characteristic feature of cultured interstitial cells is the bell-shaped profile of the dose-response curve for gonadotropin stimulated androgen production. This profile is the result of a steroidogenic lesion situated at the level of the 17 alpha-hydroxylase and/or 17,20-desmolase and induced by high concentrations of gonadotropins. Daily changes with medium supplemented with LH or FSH, initiated on day 3 of culture, prevent a further loss of steroidogenic potential, restore the ability to produce C19-derivatives, and tend to normalize the dose-response curve for gonadotropin stimulated production of androgens.
 ...
PMID:Androgen and progestogen production in cultured interstitial cells derived from immature rat testis. 629 Jul 87


1 2 3 Next >>