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Biomedical subjects

E Dahlberg

Publications and source records attributed to E Dahlberg.

33 records · Page 2Linked to original sources
PubMed1982

Characterization of the cytosolic estrogen receptor in rat skeletal muscle.

A charcoal assay and the synthetic estrogen [6,7-3H]R 2858 (17 alpha-ethynyl-11 beta-methoxyestradiol-17 beta) were used to show that rat skeletal muscle cytosol contains an estrogen receptor, which was characterized with regard to association and dissociation rate-constants at several temperatures. The degradation kinetics was also studied, and was more rapid in the absence than in the presence of ligand. Association, dissociation and degradation were all temperature-dependent. The apparent equilibrium dissociation constant (Kd), however, was not temperature-dependent, and was about 0.1-1.0 nM, whether calculated from the rate constants or determined by Scatchard analysis. Estradiol-17 beta and R 2858 were compared as ligands for Scatchard analysis; the maximum number of binding sites being about the same (120 and 110 fmol/g tissue, respectively, but the Kd was lower for estradiol-17 beta (0.16 nM) than for R 2858 (0.73 nM). Ligand specificity studies (using [3H]R 2858 as well as [3H]estradiol-17 beta) showed that R 2858 binds to an estrogen receptor in rat skeletal muscle. The estrogen receptor interacted both with heparin and with DNA covalently coupled to agarose, and was eluted from either column by NaCl. Chromatography of crude cytosol on heparin-agarose or DNA-agarose lead to an at least 10-fold or 25-fold purification of the estrogen receptor, respectively. DNA-agarose chromatography or ammonium sulfate precipitation did not separate the estrogen receptor from the androgen or glucocorticoid receptors in rat muscle.

Animals↗
PubMed1981

Instrument for distraction by limited surgery in scoliosis treatment.

A principle for secondary instrumental spinal distraction by a rod appliance of the Knodt and Harrington types is described. The principle entails of the rotation of the screw rod by wire traction. The wire is, in a secondary procedure, unwound from a wire barrel mounted onto the screw rod in the primary operative procedure. The study describes the devices employed, modified according to the wire traction--instrument distraction principle. Previous results from intra-vital studies of the Harrington instrumentation have been reported from experiments performed. Thus, a final distraction force of 18 kp effected for correction of a scoliosis curvature, was taken as a value of distraction prior to secondary instrumental distraction by wire traction. In the extra vital study, the wire traction was adjusted to surmount a compressive force of 20 kpby means of a Bessmann weight scale. Wire traction created a distraction force of 39.5 kp, and a metric distraction, from the position resulting from 20 kp distraction to that resulting from 39.5 kp distraction, of 2.8 mm, which was considered to affect the prevailing scoliosis geometry to a considerable and sufficient extent.

Humans↗
PubMed1981

Regulation of the androgen and glucocorticoid receptors in rat and mouse skeletal muscle cytosol.

Using a charcoal technique, we determined the relative binding affinity of some anabolic compounds for the androgen and glucocorticoid receptors in cytosol from rat skeletal muscle. Only a few of the compounds analyzed competed for the receptor-binding sites. The androgen and glucocorticoid receptors were analyzed in rat and mouse skeletal muscle cytosols by Scatchard analysis. In rats grouped according to sex and age, the cytosolic protein content was about the same in all groups, but the DNA content decreased with increased weight of the animal regardless of sex (male, female, or castrated male). The glucocorticoid receptor did not differ in concentration (2-3 pmol/g tissue) or ligand affinity (Kd, 10-40 nM) among the groups, but the androgen receptor concentration decreased with increased weight and age of the animals, more in the case of males than in the case of females or castrates. The Kd for the androgen receptor increased with age in males but was constantly about 0.2 nM for castrates or females. In adult intact rats, the androgen and glucocorticoid receptor concentrations in muscle cytosol from females were about 100 and 3000 fmol/g tissue, respectively, the corresponding values for males being about 50 and 2000 fmol/g tissue, respectively. Short term castration or adrenalectomy increased the concentration of and ligand affinity for the androgen and glucocorticoid receptors, respectively. After long term castration of male rats, the concentration of both receptors increased during 5 weeks to about the female level, only to decrease later. Neonatally castrated male rats had about the same androgen receptor concentrations and Kd values as female rats. Female mice had higher androgen receptor concentrations (approximately 700 fmol/g tissue) than rats. Intact male mice had about 200 fmol androgen receptor-binding sites/g tissue, and the same amount was found in mice bearing the testicular feminization (Tfm) mutant gene. In summary, the concentrations of androgen and glucocorticoid receptors in rat skeletal muscle are regulated at least by the testes. The presence of androgen receptors in skeletal muscle from Tfm mice is surprising and may motivate a reinvestigation of the regulation of androgen receptors in Tfm animals.

Animals↗
PubMed1981

Androgen and glucocorticoid receptors in porcine skeletal muscle.

The presence of free androgen and glucocorticoid receptors was demonstrated in the rectus femoris muscle of the pig. No detectable free androgen receptors were observed in intact male pigs. Androgen receptor characteristics in castrates and gilts were related to the growth rate of the lean meat in the ham. The amount of free androgen receptor was less (P less than .05) and the androgen was more tightly bound to its receptor (P less than .05) in pigs with above-average ham growth. Moreover, a higher DNA content (P less than .01) was also found in these pigs, giving a lower (P less than .05) protein to DNA ratio. The anabolic action of androgens is likely to be mediated via androgen receptors in skeletal muscle cytosol. The amounts of free glucocorticoid receptors found were influenced by the pH of the cytosolic fraction. The relationships between cytosolic pH and both the amount of glucocorticoid receptor (positive; P less than .01) and plasma levels of cortisol (negative; P less than .05) might reflect the stress to which the pigs are exposed at slaughter.

Animals↗
PubMed1980

Comparison of the R-3327H rat prostatic adenocarcinoma to human benign prostatic hyperplasia and metastatic carcinoma of the prostate with regard to steroid hormone receptors.

Quantitative analyses of cytosolic steroid hormone receptors were performed on nine tumors from the transplantable rat prostatic adenocarcinoma R-3327H. Androgen receptors and estrogen receptors were found in eight of nine and five of six tumors, respectively. None of the tumours analyzed contained detectable progestin or glucocorticoid receptors (four and seven tumors, respectively). The apparent equilibrium dissociation constants for the androgen and estrogen receptors were 0.7-4.3 nM and 0.6-1.8 nM, respectively. The apparent equilibrium Bmax values (maximum number of binding sites) were 1,500-25,000 fmoles/gm tissue for the androgen receptor and 640 to 5,800 fmoles/gm tissue for the estrogen receptor. A comparison between the receptor contents of the R-3327H rat tumor and human benign prostatic hyperplasia and metastatic carcinoma of the prostate showed that the rat tumor was different from the human tissues in several respects. Hence, the search for an optimal animal model for prostatic carcinoma in man must be continued.

Adenocarcinoma↗
PubMed1980

Characterization and quantification of the androgen and glucocorticoid receptors in cytosol from rat skeletal muscle.

The binding of the radioactive synthetic hormonal steroids [3H]dexamethasone (9 alpha-fluoro-11 beta, 17 alpha, 21-trihydroxy-16 alpha-methyl-1,4-pregnadiene-3,20-dione) and [3H]methyltrienolone (17 beta-hydroxy-17 alpha-methyl-4,9,11-estratien-3-one) to cytosol from rat skeletal muscle was studied using dextran-coated charcoal to separate unbound and receptor-bound steroid. The rates of association, dissociation, and degradation of the complexes of dexamethasone and methyltrienolone with receptor were highly dependent on temperature. The temperature dependence of association was greater for dexamethasone, and that of degradation was greater for methyltrienolone. Dissociation rates were insignificant for both steroid-receptor complexes compared to association and degradation rates. The apparent equilibrium dissociation constants for the binding of dexamethasone and methyltrienolone to their receptor binding sites were about 7 and 0.3 nM, respectively, regardless of temperature (0. 15 or 23 degrees C). The lack of influence of temperature on the equilibrium constants indicate that the binding was of hydrophobic character, and the corresponding free energy changes upon binding of dexamethasone and methyltrienolone to their respective binding sites were -41 and -49 kJ mol-1 under equilibrium conditions at 0 degrees C. The apparent maximum number of binding sites determined from Scatchard plots under these conditions was about 1900 fmol/g of tissue, 3500 fmol/mg of DNA or 30 fmol/mg of protein in the case of the dexamethasone receptor, and the corresponding figures for the methyltrienolone were about 100 fmol/g of tissue, 200 fmol/mg of DNA or 2 fmol/mg of protein. The ligand specificities of the binding sites for dexamethasone and methyltrienolone were typical of a glucocorticoid and an androgen receptor, respectively. Both steroid-receptor complexes were retained on DNA-cellulose columns, and were eluted by NaCl at an ionic strength of 0.1. The DNA-cellulose step purified about 20 times, and was used to allow gel exclusion chromatography and electrofocusing. Both steroid-receptor complexes were excluded from a column of Sephadex G-150. Electrofocusing in preparative columns gave reproducible patterns consisting of three peaks for each receptor. The apparent isoelectric points were 5.4, 5.6 and 6.2 for the glucocorticoid receptor, and 5.9, 6.2 and 8.5 for the androgen receptor.

Animals↗
PubMed1979

Steroid receptor content in cytosol from normal and hyperplastic human prostates.

Analyses of steroid hormone receptors were performed using a dextran-coated charcoal technique in cytosolic preparations from 40 cases of benign prostatic hyperplasia (BPH) and 10 normal human prostates. Binding data were calculated according to Scathchard. In all BPH specimens, receptors for the synthetic androgen methyltrienolone (MT) were found (mean maximum number of binding sites, 566 fmol/mg DNA; mean Kd, 0.61 nM), and 25 of 28 samples contained progestin [17 alpha, 21-dimethyl-19-nor-4.8-pregnadiene-3,20-dione (R5020)] receptors (mean maximum number of binding sites, 420 fmol/mg DNA; mean Kd, 0.39 nM). No specimen contained glucocorticoid [dexamethasone (9 alpha-fluoro-16 alpha-methyl-11 beta, 17 alpha, 21-trihydroxy-1,4-pregnadiene-3,20-dione); n = 16] or estrogen [17 beta-estradiol or 11 beta-methoxy-17 alpha-ethynyl-17 beta-estradiol (R2858); n = 26] receptors. No correlations were found between receptor content and age of the patients, weight of adenomas, or percentage of different cell types within the specimens. MT receptors were found in all normal prostates, while 5 of the specimens lacked progestin receptors. Estrogen receptors were found in 3 of the normal prostates, whereas none contained glucocorticoid receptors. The ligand specificity of the MT receptor in a normal prostate with minor amounts of progestin receptors was typical of an androgen receptor, and the ligand specificity of the R5020 receptor in a BPH specimen was typical of a progestin receptor. MT and R5020 had approximately the same affinity for the progestin receptor, whereas the relative binding affinity of R5020 for the androgen receptor was below 0.02 compared to that of MT. The androgen receptor was found to be more stable during repeated freezing and thawing than the progestin receptor.

Binding, Competitive↗