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Biomedical subjects

J B Adams

Publications and source records attributed to J B Adams.

At least 73 records · Page 4Linked to original sources
PubMed1983

Enzymic synthesis of steroid sulfates XVI. Specificity and regulation of human adrenal hydroxysteroid sulfotransferase.

Pure hydroxysteroid sulfotransferase (EC 2.8.2.2) of human adrenal glands possesses a wide substrate specificity towards steroids. This wide specificity has now been found to extend to simple alcohols; normal aliphatic alcohols from C3 onwards acting as substrates with C9 showing the highest rate. Increased rate was accompanied by a decrease in Km. In marked contrast to the sulfurylation of steroids such as dehydroepiandrosterone, which exhibit wave-like kinetics, the kinetics with simple alcohols were of the normal Michaelis-Menten type. By means of enzyme antibody and enzyme stability studies evidence was provided that one and the same enzyme was responsible for sulfurylation of hydroxyls on the 3- and 17- positions of steroids and simple alcohols. The data lend support to previous evidence that the enzyme controls the secretion of dehydroepiandrosterone sulfate via steroid-specific binding sites, enabling self-regulation in response to ACTH action.

Adrenal Glands↗
PubMed1983

Dehydroepiandrosterone sulfotransferase localization in human adrenal glands: a light and electron microscopic study.

Dehydroepiandrosterone sulfate is the major secretory product of the human adrenal cortex. The enzyme responsible for the sulfurylation, which has been isolated previously, possesses kinetic properties suggesting that it plays an important regulatory role in dehydroepiandrosterone sulfate secretion. In order to study the localization of the enzyme in the respective zones and cells of the cortex, an antibody to the pure enzyme was raised and the immunoglobulin G fraction employed in the peroxidase-antiperoxidase method. Staining was confined to the zona reticularis but was unevenly distributed throughout the cells. Electron microscopic examination of sections prepared from fresh adrenal tissue fixed in glutaraldehyde, revealed that the enzyme was predominantly clustered around lipid droplets. It is suggested that this may reflect an association of organelles, cholesterol being transported from lipid droplets to surrounding mitochondria, and pregnenolone then being converted to dehydroepiandrosterone in the adjacent endoplasmic reticulum and thence immediately sulfurylated.

Adrenal Glands↗
PubMed1982

Enzymic synthesis of steroid sulphates. XV. Structural domains of oestrogen sulphotransferase.

Pure preparations of oestrogen sulphotransferase (3'-phosphoadenylylsulphate:oestrone sulphotransferase, EC 2.8.2.4), exhibiting the normal four-isoenzyme pattern on gel electrophoresis, revealed limited proteolytic splits in the protein chain when examined by SDS-polyacrylamide gel electrophoresis. In addition to the normal 74000 molecular weight (74 kDa) protein band, an additional major band was seen at 36 kDa, often accompanied by band at 24kDa and 12kDa. Such preparations, either alone, or after reduction and S-carboxymethylation, showed an extremely strong resistance to dissociation, a concentration of 2% SDS being required for dissociation on Sephadex G-100 column chromatography. These lower molecular weight fragments, isolated by several techniques employing dissociative conditions, all showed a remarkable ability to reassociate to a species of approx. Mr 70000 when examined by SDS-polyacrylamide gel electrophoresis. In addition, the 12kDa fragment yielded dimeric, trimeric, tetrameric, pentameric and hexameric forms. Results of amino acid analyses and tryptic digestion fingerprints of the 36kDa, 24kDa and 12kDa fragments, in conjunction with N-terminal amino acid determinations, suggested in initial protease cleavage at a susceptible region midway in the chain. One, or both, of the resultant 36kDa lobes was then further attacked to yield the 12kDa and 24kDa species - the latter again being capable of cleavage to two 12kDa species. Tryptic maps indicated that the 12kDa, 36kDa and 72kDa species were discrete polypeptide chains and not composed of subunits of the 12kDa species. These data suggest that the enzyme contains a number of domains and that strong interaction occurs between them. If these domains possess oestrogen-binding properties this would explain the most unusual wave-like kinetics exhibited by the enzyme consistent with a rate equation of degree greater than 4. Such properties also provide evidence further to that previously reported which suggests that the enzyme may be genetically related to serum albumin.

Amino Acids↗
PubMed1982

Estrogen sulfurylation as an alternative indicator of hormone dependence in human breast cancer.

Estrogen receptor (ER) levels, formation of 3'-phosphoadenosine-5'phosphosulfate (PAPS), and sulfate transfer to estradiol-178, have been determined in 62 human primary carcinoma cytosol preparations. Whilst no differences between ER positive and ER negative tumors were found in the synthesis of [35S]PAPS, formation of estradiol-3-[35S]sulfate catalysed by estrogen sulfotransferase was significantly higher in ER positive tumors [84 +/- 10 (mean +/- S.E.M.) versus 32 +/- 9 pmole estradiol-3-sulfate per mg protein per 2 hr for ER positive and ER negative tumors, respectively, p less than 0.02]. By choosing a discriminating value for estrogen sulfurylation of 40 pmole per mg protein per 2 hr, then 16/19 (84%) of the ER negative tumors were below this point. Since previous data had shown that 20/23 (87%) progesterone receptor negative tumors were also below this value (Pewnim, Adams and Ho, CANCER RES. 40, 1360 (1980), an alternative simple method, having a high potential for the evaluation of hormone responsiveness in mammary cancer, is suggested.

Breast Neoplasms↗
PubMed1982

Induction of estrogen sulfotransferase in the human endometrium by progesterone in organ culture.

It has been established that progesterone will induce 17 beta-estradiol (E2) dehydrogenase in the human endometrium. Whether it plays a similar role in the induction of estrogen sulfotransferase is not known, although this is likely, since estrone sulfate is the main metabolite of E2 when incubated with secretory, but not proliferative, human endometrium. We have now examined the influence of progesterone on both enzymes in endometrial tissue in organ culture. Estrogen sulfotransferase activity was not detectable in the cytosol of proliferative tissue when cultured in the absence of hormone, but was induced by culture in the presence of progesterone to a value (mean +/- SEM) of 19.7 +/- 5.3 pmol E2-3-sulfate h-1 mg cytosol protein-1. A significant (P less than 0.05) induction of E2 dehydrogenase activity was also observed in the same tissues [from 3.7 +/- 1.9 to 10.4 +/- 2.7 (mean +/- SEM) nmol estrone h-1 mg microsomal protein-1]. Corresponding values for secretory endometrium, when cultured under identical conditions in the absence of progesterone, were 20.3 +/- 11.6 pmole h-1 mg-1 and 31.1 +/- 25.1 nmol h-1 mg-1 for estrogen sulfotransferase and E2 dehydrogenase, respectively. Values not significantly different from these were obtained when progesterone was present in the cultures. These data indicate that progesterone secretion during the luteal phase is responsible for the induction of both E2 dehydrogenase and sulfotransferase activities in the endometrium. It is likely that these enzymes are closely coupled, resulting in the rapid metabolism of E2 by formation and excretion of estrone sulfate.

Chromatography, Thin Layer↗
PubMed1981

Enzymic synthesis of steroid sulphates. XIV. Properties of human adrenal steroid alcohol sulphotransferase.

Pure steroid alcohol sulphotransferase (EC 2.8.2.-) has the property of sulphurylating hydroxyl groups on different positions of the steroid ring. It has now been established that although only monosulphates are formed from substrates such as 3,17-diols, the position of the sulphate group depends on the relative configuration of the hydroxyl groups. Androst-5-ene-3 beta,17 beta-diol, for example, is sulphurylated mainly at the 17-position. In addition, compounds such as epitestosterone and 17 alpha-estradiol are sulphurylated at much higher rates than their respective 17 beta-epimers. It is believed that the steroid can approach the sulphurylation site via (i) ring A with the beta-side upwards, and in this mode a 3 beta-hydroxyl is sulphurylated at a higher rate than a 3 alpha-hydroxyl, or (ii) ring D with the beta-side downwards, and in this mode a 17 alpha-hydroxyl group is oriented in an analogous fashion to the 3 beta-hydroxyl in (i). The enzyme exhibits non-Michaelis-Menten kinetics within physiological concentrations (0-2 micro M) of the substrate dehydroepiandrosterone and evidence was obtained for the presence of multiple interacting steroid-binding sites. A regulatory role for the enzyme in the secretion of dehydroepiandrosterone from the human adrenal gland is proposed.

Adrenal Glands↗
PubMed1980

Enzymic synthesis of steroid sulphates. XIII. Isolation and properties of dehydroepiandrosterone sulphotransferase from human foetal adrenals.

Human foetal adrenals have provided a rich source of steroid alcohol sulphotransferase (EC 2.8.2.-). The latter was isolated in pure form in one step by affinity chromatography on an (NH4)2SO4 cut derived from the cytosol fraction of the glands. The yield was 6-fold higher than that obtained from adult human adrenals. General properties of the enzyme are given and it appears to be identical to that obtained previously from adult human adrenals.

Adrenal Glands↗
PubMed1980

Effect of hormone manipulation on oxidation, reduction and sulphurylation of dehydroepiandrosterone and oestrone in DMBA-induced rat mammary tumours.

Using the DMBA-induced mammary tumour as a model, the effect of hormone manipulation on steroid sulphurylation and on oxidative and reductive metabolism has been investigated. Oestradiol-17 beta, or oestradiol-17 beta + progesterone, administered to oophorectomized animals, had no effect on adenosine-3'-phosphate-5'-phosphosulphate formation in the tumours. Dehydroepiandrosterone sulphotransferase was also unaffected. A large increase in oestrogen sulphotransferase following administration of oestrogen + progesterone was observed in some but not all tumours, and the overall results were not statically significant. The major metabolities of dehydroepiandrosterone, by both human and carcinogen-induced rat mammary tumours in vitro, are 7-oxygenated derivatives. Oestrogen administration led to a significantly decreased production of total 7-oxygenated derivatives of dehydroepiandrosterone. Conversion to 5-androstene-3 beta, 17 beta-diol was unaffected by the hormones. The rate of formation of oestradiol-17 beta from oestrone was increased 5-fold in growing tumours from animals receiving oestrogen, or oestrogen + progesterone, compared to regressing tumours in oophorectomized control animals.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1980

Dehydroepiandrosterone and androst-5-ene-3 beta,17 beta-diol in human mammary cancer cytosolic and nuclear compartments and their relationship to estrogen receptor.

Dehydroepiandrosterone (DHEA) and 5-androstene-3 beta,17 beta-diol (ADIOL) were determined by radioimmunoassay in human primary mammary cancer cytosol preparations. The range and means +/- S.D. (ng/g, wet weight, of tissue) in individual tumors were: DHE, 12.3 +/- 14.4, n = 34; and ADIOL, 2.7 +/- 2.1, n = 43. In 23 tumors in which both steroids were measured in the same extract, they were significantly correlated, and in these tumors the ratio of ADIOL to DHEA was lower in estrogen receptor (ERC)-negative than in ERC-positive tumors, but this difference was not significant. The ratio of ADIOL to DHEA was 5-fold higher in purified nuclei obtained from pooled primary mammary cancer tissue compared to that in the cytosol. DHEA was present in the cytosol of tumors from premenopausal women in significantly higher concentrations than in cytosols of postmenopausal women [0.73 +/- 0.49 ng/mg cytosol protein (n = 14) versus 0.35 +/- 0.35 (n = 19); p < 0.02], whereas the concentrations of ADIOL were similar [0.12 +/- 0.09 ng/mg cytosol protein (n = 18) and 0.10 +/- 0.11 (n = 25), for pre- and postmenopausal women, respectively]. In ERC-positive tumors, there was a negative correlation between ERC concentration and cytosol ADIOL levels in both premenopausal (r = -0.46, n = 10) and postmenopausal (r = -0.24; n = 20) subjects and also DHEA levels in postmenopausal women only (r = -0.30; n = 12). However, none of these correlations reached statistical significance. In view of the known high affinity of ADIOL for ERC (Kd approximately 6 nM) and its estrogen-like activity in vivo, these data suggest that the concentration of ADIOL in the tumor cytosols is sufficiently high to translocate ERC and provoke an estrogen response.

Androstenediol↗
PubMed1980

A relationship between estrogen sulfurylation and estrogen and progesterone receptor status in human mammary carcinoma.

It was previously demonstrated that a correlation existed between estrogen receptor (ER) status and levels of estrogen sulfotransferase in human mammary cancer, high levels being associated with ER-positive and low levels with ER-negative tumors. We have now examined these same parameters, along with progesterone receptor (PGR) status, in 44 primary human mammary tumors. Tumors which were both ER-positive and PGR-positive (n = 21), showed significantly higher levels of estrogen sulfotransferase compared to ER-positive PGR-negative (n = 12) and ER-negative PGR-negative (n = 11) tumors. These values (pmol estradiol sulfate per mg protein per 2 hr) were 72 +/- 12 (S.E.), 25 +/- 5, and 11 +/- 4 (p less than 0.01 and less than 0.005, respectively). There was no significant difference between ER-positive PGR-negative and ER-negative PGR-negative tumors. The possible involvement of PGR in the regulation of estrogen sulfotransferase is discussed.

Adult↗
PubMed1979

A correlation between estrogen sulfotransferase levels and estrogen receptor status in human primary breast carcinoma.

Estrogen sulfotransferase (EC 2.8.2.4) activity and estrogen receptor levels were measured in 32 human primary breast cancer cytosol preparations. Two types of tumors were identified: type 1, in which estrogen sulfotransferase levels were low (less than 40 pmol 17 beta-estradiol 3-sulfate formed per mg protein per 2 hr) and were independent of [35S]adenosine 3'-phosphate 5'-phosphosulfate production from [35S]sulfate and adenosine triphosphate, and type 2, in which estrogen sulfotransferase levels ranged from 50 to 200 pmol 17 beta-estradiol 3-sulfate per mg protein per 2 hr and were correlated with [35S]adenosine 3'-phosphate 5'-phosphosulfate formation (r = 0.70; p less than 0.005). In type 1 tumors, 11 of 16 were estrogen receptor negative; in type 2 tumors, 2 of 16 were receptor negative. Estrogen sulfotransferase levels in receptor-negative tumors were significantly lower than the levels in receptor-positive tumors (p = 0.025).

Breast Neoplasms↗
PubMed1978

Discontinuous transition of myelin structure at the junction between central and peripheral components of the eighth cranial nerve, as disclosed by X-ray diffraction.

Scanning along human acoustovestibular nerves from cross-sections closely proximal to the brain to locations distinctly peripheral thereto, by means of small-angle X-ray diffraction, has disclosed transitional junctions at which the myelin structure typical of central nervous system (CNS) axons gives way to one characteristic of peripheral (PNS) fibers. The junctions correspond to regions along the nerves, previously recognized histologically, at which the satellite cells responsible for axon myelination change character, from the oligodendrocytes of the CNS to the Schwann cells of the PNS. Thus the structural discontinuity between the CNS and PNS myelins can be ascribed to differences in the biosynthetic processes of the respective satellite cells. Junctions of this kind are to be expected in all cranial and spinal roots near the locations where they leave the CNS.

Humans↗
PubMed1978

Products of dehydroepiandrosterone metabolism by human mammary tumors and their influence on estradiol receptor binding.

The high concentrations of dehydroepiandrosterone and its 3beta-sulfate in the blood are potential preocursors for further metabolism by normal and tumorous human mammary tissue. In vitro metabolism of 7n-3H- and 1,2,6,7(n)-3H-dehydroepiandrosterone by fifteen mammary tumors was examined. Some 10--50% of the radioactivity recovered was in the form of 7-oxygenated derivatives: the major metabolite being 7alpha-hydroxydehydroepiandrosterone accompanied by lesser amounts of the 7beta-epimer. 5-Androstene-3beta,17beta-diol was formed in all but one case. Evidence showed that the high yield of 7alpha-hydroxy derivative resulted from direct action of a 7alpha-hydroxylase capable of using both dehydroepiandrosterone and 5-androstene-3beta,17beta-diol as substrates. Although 5-androstene-3beta,17beta-diol competed with estradiol-17beta for the estrogen receptor, this property was considerably reduced as a consequence of the introduction of a 7alpha-hydroxyl or 16alpha-hydroxyl group. Dehydroepiandrosterone, which competed less effectively for the estrogen receptor site, showed almost no affinity for the site upon the introduction of a 7alhpa-hydrocyl group. A regulatory role for the 7alpha-hydroxylase is outlined.

Androstenediols↗