Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Transcortin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed1982

A binding-protein for aldosterone in human plasma.

Equilibrium dialysis of fresh human plasma revealed that aldosterone was bound to plasma proteins other than albumin. The apparent association constant of aldosterone to nonalbumin plasma proteins was one order of magnitude larger than that reported for aldosterone to corticosteroid-binding globulin (CBG), while its binding capacity was smaller than that of CBG. Bound aldosterone was not completely dissociated when the binding capacity of CBG was saturated with a large amount of cortisol. The addition of aldosterone under these experimental conditions further displaced its binding to nonalbumin plasma proteins. Progesterone inhibited binding of aldosterone but not to the same extent as cortisol did. Column electrophoresis of dialyzed plasma demonstrated, in addition to the peak of aldosterone binding to CBG and albumin, a peak of aldosterone comigrating with alpha 1-globulin. When the fractions containing this peak were pooled and subjected to equilibrium gel filtration on Sephadex G-200, bound aldosterone was eluted between CBG and albumin. Desialylated plasma also showed a peak of aldosterone binding different from the peaks corresponding to CBG and albumin on gel filtration. This aldosterone-binding protein was a glycoprotein precipitable with 60% saturation of ammonium sulfate and completely inactivated by heating at 60 degrees C for 30 min. These results suggest the existence of an aldosterone-binding protein in human plasma different from CBG, albumin and alpha 1-acid glycoprotein.

Binding, Competitive↗
PubMed1983

The determination of maternal and foetal rat plasma corticosterone concentration in late pregnancy by competitive protein binding analysis.

A procedure for the determination of corticosterone in 20 microliters of rat plasma, in maternal and foetal late pregnancy with a protein binding radioassay, is described. The method is suitable in a range of 0.5-3 ng of corticosterone. An amount of 0.5 ng can be detected with a coefficient of variation for duplicate of 13%. This procedure seems to be specific for glucocorticosteroids. The comparison of the results obtained with fluorimetry and the competitive protein binding radioassay show the reliability of both methods although the protein binding radioassay is much more sensitive.

Animals↗
PubMed1984

Human corticosteroid binding globulin is secreted by a hepatoma-derived cell line.

We used a sensitive radioimmunoassay for corticosteroid-binding-globulin (CBG) to demonstrate that a human hepatoma-derived cell line secretes a protein which: (a) the radioimmunoassay cannot distinguish from CBG; (b) has the same Stokes' radius as CBG; (c) is absorbed by a steroid affinity column which is specific for CBG.

Carcinoma, Hepatocellular↗
PubMed1984

Characterization of human spleen tumor glucocorticoid receptors using [3H]cortisol as ligand.

The present report describes an assay system allowing the quantification and characterization of [3H]cortisol binding to glucocorticoid receptors in bloodrich human tissue. The essence of this assay lies in the selective binding of 17 beta-carboxylic acids of natural corticoids to corticosteroid binding globulin (CBG). In the presence of 1240 nmol/l 11 beta-hydroxy-3-oxo-4-androstene-17 beta-carboxylic acid only glucocorticoid receptors were detectable with the expected properties: high affinity for synthetic and natural glucocorticoids, but failure to bind to the respective 17 beta-carboxylic acids, apparent Kd's at 0-4 degrees C for [3H]cortisol of approx 30 nmol/l, Nmax similar to those determined with [3H]dexamethasone and the typical sequence of relative binding affinities (dexamethasone greater than cortisol greater than progesterone greater than 17 beta-methyl-testosterone, estradiol).

Binding, Competitive↗
PubMed1985

Rat corticosteroid-binding globulin (CBG) biosynthesis by fetal hepatocytes in culture.

The ability of fetal liver to synthesize and secrete corticosteroid-binding globulin (CBG) was investigated using primary cultures of hepatocytes transplanted from 15- and 18-day-old rat fetuses. Analysis of culture medium, after labelling with [14C]leucine, by crossed immunoelectrophoresis, clearly demonstrated CBG, albumin and alpha-fetoprotein (AFP) secretion. The relative rate of CBG secretion was more important at the younger stage. Indirect immunofluorescence permitted localization of CBG in fetal hepatocytes. The results suggest that the high level of CBG found in fetal serum is mainly produced by the liver of the fetus itself.

Animals↗
PubMed1986

Anatomical resolution of two types of corticosterone receptor sites in rat brain with in vitro autoradiography and computerized image analysis.

The rat brain contains two receptor systems for corticosterone (CORT): the glucocorticoid (GR) and corticosterone or mineralocorticoid-like (CR) receptor sites. We have studied the localization of these receptors by in vitro autoradiography and by in vitro cytosol binding assays in microdissected brain areas. In vitro autoradiography revealed that CR receptor sites are almost entirely restricted to the septal-hippocampal complex, whereas the presence of GR extends throughout the brain. Highest levels of GR are present in the lateral septum, hippocampal, cortical and thalamic regions and the paraventricular nucleus. In vitro determination of binding of 3H-labelled steroids to CR and GR in cytosol of "punched out" brain tissue revealed a similar neuroanatomical distribution as observed with the autoradiographic analysis. In addition, it was found that CORT binds to CR (KD approximately 0.5 nM) with 5-10-fold higher affinity than to GR (KD approximately 2.5-5 nM).

Androstanols↗
PubMed1986

Mineralcorticoid receptor from rat kidney. Interaction with heparin and purification to a CBG-free stage.

Purification of the mineralcorticoid receptor is a particularly challenging problem. This receptor is present in target tissues at concentrations lower and is less stable than any other steroid receptor. Addition of molybdate ions (20 mM) to rat kidney cytosol enhances stability of mineralcorticoid-specific binding sites: the inactivation rate at 0 degrees C decreases from 7.2 to 1.7% per hour in the absence of aldosterone, and from 1.8 to 0.3% per hour in the presence of hormone. Rates of inactivation in the presence of molybdate are thus compatible with purification procedures. Also, the corticosteroid-binding globulin (CBG) is an important contaminating component of kidney cytosol because it cannot be specifically blocked preliminarily to affinity chromatography. We show that when kidney cytosol is incubated with heparin covalently linked to Sepharose (Sepharose-heparin), after 30 min at 0 degrees C more than 80% of the mineralcorticoid-specific binding sites interact strongly with Sepharose-heparin while CBG is not bound at all. The mineralcorticoid-specific binding sites can be recovered from Sepharose-heparin by washing with heparin (2 mg/ml; recovery up to 90%), KCl (0.3 M; recovery up to 90%); and, less efficiently, with total liver RNA (2 mg/ml; recovery up to 55%) and dextran sulfate (2 mg/ml; recovery up to 40%); little or no recovery is achieved with chondroitin sulfate, sonicated DNA, pyridoxal-5-phosphate, dextran, d-glucosamine and d-glucuronic acid. With demonstration that also the mineral-corticoid receptor binds to heparin, this property has become a general hallmark of steroid receptors. If the "heparin" binding site of steroid receptors is of physiological significance it remains to be established. By application of the newly found property of the mineralcorticoid receptor, an overall 10-fold purified, CBG-free preparation of this receptor can be obtained from kidney cytosol with a single chromatography on Sepharose-heparin.

Aldosterone↗
PubMed1987

Inhibition by cortisol of human natural killer (NK) cell activity.

The effects of cortisol on the natural killer (NK) activity of human peripheral blood mononuclear (PBM) cells were studied in vitro using a direct 4-h 51Cr-release assay and K 562 cell line as a target. Preincubation for 20 h of PBM cells drawn from healthy donors with 1 X 10(-8) to 1 X 10(-5) M cortisol resulted in a significant decrease of NK cell activity. The magnitude of the suppression was directly related to the steroid concentration and inversely related to the number of effector cells. Cortisol was able to minimize the enhancement of NK cytotoxicity obtainable in the presence of immune interferon (IFN-gamma). A significantly higher suppression was achieved after sequential exposure of PBM cells to cortisol and equimolar levels of prostaglandin E2 (PgE2). The concomitant incubation with theophylline and isobutyl-methylxanthine failed to enhance the cortisol-induced suppression, whereas PgE2-dependent inhibition significantly increased after exposure of PBM cells to methyl-xanthines. The inhibitory effect of cortisol was partially or totally prevented by the concomitant incubation with equimolar amounts of 11-deoxycortisol and RU 486 but not of progesterone. Treatment of NK effectors with a monoclonal anti-human corticosteroid-binding globulin (CBG) antibody produced an enhancement of the spontaneous NK activity and a partial suppression of cortisol-mediated effects. Our results suggest that endogenous glucocorticoids play a role in the regulation of NK cell-mediated cytotoxicity. Since the effect of cortisol was additive to that of PgE2 and was not changed by phosphodiesterase inhibitors, it is conceivable that the hormone acts at a level different from the adenylate cyclase-phosphodiesterase system. Data obtained with the use of antiglucocorticoids and the anti-CBG antibody are compatible with a role both of high-affinity glucocorticoid receptors and of CBG in mediating cortisol action on the human NK cell activity.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Clinical use of unbound plasma cortisol as calculated from total cortisol and corticosteroid-binding globulin.

A method to calculate unbound cortisol from total cortisol (measured by competitive protein binding) and CBG (measured by radial immunodiffusion) based on the binding equilibrium has been evaluated. The calculated results (y) correlate well with those (x) obtained by centrifugal ultrafiltration at 37 degrees C (y = 1.04 x - 2.11 ng/ml; r = 0.975; n = 150). The concentration of CBG is similar in normal men (37.7 +/- 3.5 (SD) micrograms/ml; n = 12) and women (39.5 +/- 3.7 (SD) micrograms/ml; n = 7) and shows no diurnal variation, but marked diurnal variation is observed for total cortisol (193.7 +/- 35.0 (SD) ng/ml at 08.00 h vs 43.2 +/- 23.3 (SD) ng/ml at 22.00 h; n = 19) and particularly for unbound cortisol (16.5 +/- 5.6 (SD) ng/ml at 08.00 h vs 2.3 +/- 1.8 (SD) ng/ml at 22.00 h; n = 19). The concentration of CBG (89.1 +/- 11.2 (SD) micrograms/ml) and of total cortisol (395.6 +/- 103.3 (SD) ng/ml at 08.00 h; 110.3 +/- 16.6 (SD) ng/ml at 22.00 h) are clearly elevated in estrogen treated women (n = 11) but unbound cortisol levels (17.2 +/- 7.7 (SD) ng/ml at 08.00 h; 2.5 +/- 0.5 (SD) ng/ml at 22.00 h) are similar to the control group. The concentration of CBG is significantly decreased in patients with Cushing's syndrome (33.2 +/- 5.6 micrograms/ml; n = 17) and unbound cortisol is relatively more elevated than total cortisol in these patients. In adrenal insufficiently CBG is normal, but total and unbound cortisol are markedly decreased. There is a significant decrease of CBG in hyperthyroidism (35.7 +/- 5.5 micrograms/ml; n = 22), in cirrhosis (32.0 +/- 8.0 micrograms/ml; n = 14) and in renal disease and a significant increase in patients treated with antiepileptic drugs (47.5 +/- 6.3 micrograms/ml; n = 14), but total and unbound cortisol are normal in all these conditions. We conclude that unbound cortisol can be calculated in a simple and reliable way from total cortisol and CBG and permits a better evaluation of adrenal function, particularly in patients with altered CBG concentrations.

Circadian Rhythm↗
PubMed1987

Contraceptive steroid treatment affects steroid binding proteins and the percentage of free 17 beta-estradiol and testosterone in the cynomolgus monkey (Macaca fascicularis).

The levels of steroid binding globulins were characterized in cynomolgus monkeys that were treated with contraceptive steroid preparations delivered either by intravaginal rings (CVR) or orally (OC) in the diet. Levonorgestrel (dNG) was the bioactive progestin and the estrogen was either 17 beta-estradiol (E2) in the CVR treatment or ethinyl estradiol (EE) in the OC treatment. Both contraceptive treatments lowered sex hormone binding globulin (SHBG) levels below those observed in males (P less than 0.05) and normal females (P less than 0.01). Corticosteroid binding globulin (CBG) was elevated (P less than 0.01) in the OC treatment, demonstrating the potency of EE. The distribution of E2 and testosterone (T) between binding to SHBG or albumin and the unbound fraction was calculated after the determination of the percentage of free steroid by centrifugal ultrafiltration. Both contraceptive treatments increased the percentage of free T and E2 (P less than 0.01) in the subset of monkeys that were evaluated, but the percentage bound to SHBG and albumin were different only for the CVR group (P less than 0.05). Decreased total T concentrations in the treatment groups offset any increase in free T concentrations associated with an increase in the percentage of free T. The differences in the distribution of binding to SHBG associated with these contraceptive steroid treatments was influenced more by the reduction in the binding capacity of SHBG than by the displacement of E2 and T from SHBG by dNG.

Administration, Oral↗
PubMed1988

A simple method for the purification of murine corticosteroid binding globulin: characterization of a monomer.

A fast and reproducible two-step method with high resolution was developed for purification of murine corticosteroid-binding globulin (CBG). The first step was liquid chromatography on a Sephacryl-S-200 column, and the CBG-containing residual was subsequently chromatographed by fast protein liquid chromatography (FPLC). This enabled us to quickly obtain a highly purified protein and the apparently isolated CBG was tested for its purity by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis (SDS-PAGE) and sedimentation equilibrium centrifugation. The CBG concentration in pregnant mouse serum was estimated to 0.78 g/l (1.5% of the total protein). The monomeric organization of the protein was demonstrated by mercaptoethanol treatment. No NH2-terminal amino acid could be detected, probably owing to a blocked amino acid. The mol. wt (Mr) of murine CBG was determined to be 52,000 and the sedimentation constant S20 degrees, w to 3.9 S by analytical ultracentrifugation. The protein showed 5 bands when subjected to isoelectric focusing: 3 bands with apparent isoelectric points (pI) between pH 3.15-3.25 and two between pH 3.40-3.50.

Amino Acids↗