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 433 records · Page 24Linked to original sources
PubMed1986

The dose-dependent systemic availability of prednisone: one reason for the reduced biological effect of alternate-day prednisone.

An analysis of the literature was performed, revealing that in many studies both the desired and the undesired effects are decreased in alternate-day prednisone regimens as compared with the daily regimens. In the present report evidence is given that part of the diminished biological effect of dose-spacing regimens is attributable to a decreased total exposure to prednisolone. Following a high dose of 0.8 mg kg-1 of oral prednisone or prednisolone the plasma concentration vs time curves of total prednisolone, unbound prednisolone and prednisolone bound to albumin or transcortin were always less than four times higher than following a low dose of 0.2 mg kg-1 of prednisone or prednisolone. This dose-dependent systemic availability of prednisolone explains partly the diminished biological effect when the same total amount of prednisone or prednisolone is divided into several small doses as opposed to a single oral dose.

Administration, Oral↗
PubMed1981

Human corticosteroid binding globulin.

The literature on corticosteroid binding globulin (transcortin) in the human is reviewed under the following headings: physicochemical properties, biosynthesis, measurement, and physiological, pharmacological and pathological variations with particular emphasis of the effects of pregnancy and oral contraceptives. Finally, the physiological implications of corticosteroid binding globulin are discussed.

Adrenal Cortex Diseases↗
PubMed1984

Increased plasma concentration of N-terminal beta-lipotrophin and unbound cortisol during pregnancy.

The plasma concentration of N-terminal beta-lipotrophin (beta-LPH), total and protein unbound cortisol, progesterone and the transcortin (CBG) binding parameters have been measured in 21 women in the early follicular phase and in 70 pregnant women at various stages of pregnancy. Results showed that the plasma CBG binding capacity and the concentrations of total cortisol and progesterone increased significantly at each trimester of pregnancy while the plasma concentration of unbound cortisol increased significantly only in the 2nd and the 3rd trimesters of pregnancy. In addition, a significant increase of N-terminal beta-LPH level was observed during the 3rd trimester. By chromatography, it is demonstrated that during the 3rd trimester of pregnancy the beta-LPH/gamma-LPH molar ratio decreases dramatically and that the increase of N-terminal beta-LPH concentration is mainly due to a two fold increase in gamma-LPH concentration.

Female↗
PubMed1981

Isolation and characterization of binder IIIA, a new protein which binds corticosteroid anions.

A new protein binding corticosteroid metabolites has been purified over 300-fold from liver cytosols of adrenalectomized rats, treated for 45 min in vivo with [1,2-3H]cortisol. Purification was accomplished by column chromatography on Sephadex G-25, DEAE-Sephadex A-50, Sephadex G-75, and hydroxylapatite. The protein has a Stokes radius of 2.27 nm by gel filtration and an apparent sedimentation coefficient of 3.0 S by sucrose gradient centrifugation. The calculated molecular weight is 30,700. The bound steroid was extracted and has been shown by Sephadex LH-20 chromatography to be a monosulfate derivative of cortisol. Using liver cytosol from adrenalectomized rats pretreated in vivo for 45 min with [1,2-3H]cortisol plus 1000-fold excess competing steroid, cortisol derivatives and progesterone were shown to be the most active competitors. Testosterone and 17 beta-estradiol were least active as competitors. The synthetic steroids, dexamethasone and triamcinolone, produced little or no competition. The protein has been named corticosteroid-anion binder IIIA in keeping with its elution position from a DEAE-Sephadex A-50 column, compared to other binding proteins. Binder IIIA has been separated chromatographically from the glutathione S-transferases (including ligandin) and protein z described by Arias [Levi, A.J., Gatmaitan, Z. and Arias, I.M. (1969) J. Clin. Invest. 48, 21856-21866], both of which have been shown to bind anionic metabolites. It has been resolved from the activities of transcortin, cortisone 5 beta-reductase, and 3 alpha-hydroxysteroid dehydrogenase.

Adrenalectomy↗
PubMed1985

Chick oviduct glucocorticosteroid receptor. Specific binding of the synthetic steroid RU 486 and immunological studies with antibodies to chick oviduct progesterone receptor.

The glucocorticosteroid receptor (GR) has been studied in oviduct cytosol prepared from estrogen-primed, 4-week-withdrawn chicken. The equilibrium dissociation constant was 6 nM for dexamethasone, and 18 300 receptor sites/cell were measured assuming that all cells contain identical concentrations of GR. Dexamethasone, used in most studies investigating glucocorticosteroid action, was found not to be the best GR ligand. The affinities of several natural and synthetic glucocorticosteroids for GR increased in the following order: cortisol less than deoxycorticosterone less than dexamethasone less than corticosterone less than triamcinolone acetonide. The synthetic steroid RU 486 was the most specific ligand of GR (its affinity was approximately equal to 10-fold higher than that of triamcinolone acetonide), while it did not bind either to plasma transcortin (which binds dexamethasone nor, surprisingly, to progesterone receptor (PR), contrary to what occurs in mammalian species. The molybdate-stabilized, 8-S form of GR was prepared from withdrawn chick oviduct, whole chick embryo or cultured chick embryo fibroblasts (which do not contain PR), and was labeled with either [3H]dexamethasone or [3H]RU 486. The sedimentation coefficient of radioactive ligand--8-S GR complexes was shifted towards heavier forms after incubation with polyclonal (IgG-G3) or monoclonal (BF4) antibodies generated against the molybdate-stabilized, 8-S form of the chick oviduct PR. Since neither IgG-G3 nor BF4 interacted with the steroid binding 4-S form of GR, it is suggested that these antibodies recognized a non-steroid binding protein common to molybdate-stabilized, 8-S forms of GR and PR.

Animals↗
PubMed1974

Interaction of gelatin with stereospecific binding proteins and its enhancement of competitive binding assays.

The effect of gelatin (0.5 g/l) on binding curves at high dilution of three classes of stereo-specific binding proteins was studied. These included two antibodies (to oestradiol and aldosterone), six transins (horse and dog transcortins, human thyroxine-binding globulin, human sex steroid-binding globulin, and guinea pig transprogestin), and one receptor (bovine adrenal protein kinase). Gelatin increased the apparent binding of all these proteins, particularly at the highest dilutions and sometimes in a striking manner. While much of this action can be attributed to its decreasing the adhesion of the dilute binding protein to glass, gelatin also increased the apparent uptake of some tracers by certain adsorbents. Similar findings were obtained using human gamma globulin (2 g/l). These effects resulted in increased sensitivity and improved reproducibility in the assays employing them.

Aldosterone↗
PubMed1975

Feedback inhibition of adrenocorticotropin release by corticosterone infusions in the adrenalectomized rat.

Advantage was taken of a specific and sensitive bioassay for rat plasma adrenocorticotropin (ACTH) based on the dispersion of rat adrenal cells with trysin, to investigate the relationship between plasma corticosterone concentration and inhibition of ACTH release under steady-state conditions achieved by graded rates (0-5.12 mug/min per 100 g body weight) of intravenous infusion of the steroid for 45 min in 28-day adrenalectomized rats. In contrast to prior reports involving suppression of stress-induced ACTH release, the inhibitory effect of corticosterone was shown, under our experimental conditions, to be exerted also on the basal rate of ACTH secretion. Indeed, a slight though not significant decrease of plasma ACTH concentration was observed with the corticosterone infusion rate of 0.64 mg/min per 100 g body weight, and further progressive and highly significant drops in concentration were recorded for infusion rates of 2.56 and 5.12 mg/min per 100 g body weight. An increase of the metabolic clearance rate of corticosterone, observed as a function of the infusion rate, was ascribed to saturation by the steroid of the plasma transcortin binding sites.

Adrenal Cortex↗
PubMed1982

Significance of ACTH4-10 in the control of hippocampal corticosterone receptor capacity of hypophysectomized rats.

The effect of hypophysectomy on the number of corticosterone receptor sites was investigated in three rat brain regions and was compared with the effect of long-term adrenalectomy. Subsequently, the effect on receptor capacity was measured after the hypophysectomized rats had received as substitution therapy ACTH1-24 and smaller peptide fragments lacking corticotropic activity. All rats (sham and hypophysectomy) were adrenalectomized 24 h prior to sacrifice for depletion of endogenous adrenal hormones and replacement therapy was discontinued at that time. Extensive perfusion with saline was carried out at the time of sacrifice. 3H-corticosterone binding was measured in cytosol by means of an in vitro assay. 2 weeks after hypophysectomy, the apparent maximal binding capacity (Bmax) of the corticosterone receptor system was increased by 60, 36 and 72% in hippocampus, hypothalamus and septum, respectively. The increase in Bmax in the hippocampus of hypophysectomized rats was 30% higher than the increase in animals adrenalectomized 2 weeks previously. Replacement with ACTH1-24 markedly decreased the binding capacity in all brain regions investigated. Replacement with the behaviorally active ACTH4-10 sequence reduced the number of corticosterone receptor sites in the hippocampus by 21%, while the behaviorally inactive ACTH11-24 sequence was ineffective. Des-glycinamide-arginine-vasopressin was also ineffective. There were no alterations in binding affinity for corticosterone in hippocampal cytosol after the surgical procedures or after the different replacement therapies. It is concluded that the neurotropic ACTH4-10 sequence reduces the number of corticosterone receptor sites in the hippocampus of the hypophysectomized rat. The action of ACTH4-10 was specific for the hippocampus and was not observed in other brain regions or plasma transcortin.

Adrenalectomy↗
PubMed1995

Antiestrogenic properties of raloxifene.

This 21-day, open-label study evaluated the effects of raloxifene and tamoxifen on estrogen-induced changes in serum levels of anterior pituitary hormones (prolactin, luteinizing hormone, and follicle-stimulating hormone), sex steroids (testosterone, estradiol), and binding globulins [thyroid binding globulin (T3 resin uptake), transcortin, sex steroid binding globulin]. Seventeen healthy male volunteers completed the study after being randomized to one of three treatments: raloxifene, tamoxifen, or placebo. Six subjects received raloxifene (200 mg daily) for 10 days, 6 subjects received tamoxifen [20 mg twice a day (b.i.d.)] for 10 days, and 5 subjects received placebo for 10 days. All subjects received ethinyl estradiol (20 micrograms b.i.d.) for 7 days starting 3 days after initiation of study drug or placebo treatment. Results of the primary analysis of this study indicate that for six of the seven analyzable parameters of estrogen action (excluding luteinizing hormone) raloxifene blunted the estrogen response; this effect was significant only for T3 resin uptake. Tamoxifen administration significantly blunted or reversed the estrogen effect in all six of these parameters. Raloxifene, an effective antiestrogen in animal models, is also antiestrogenic in humans.

Adult↗
PubMed1981

Lung tissue progesterone in the human fetus and neonate.

During fetal life human lungs have a high progesterone concentration (average 380 ng/g at 14 weeks of gestation and 635 ng/g at 32 weeks). At 30 h of age, this concentration had decreased to 185 ng/g. During the first 72 h of life, some infants with respiratory distress syndrome (RDS) had a higher amount of progesterone in their lungs than infants with diseases other than RDS. In newborns with RDS, serum transcortin (binding progesterone) was close to the normal value, but serum progesterone concentration 57% below normal. The hypothesis that, in addition to surfactant, lung tissue smooth muscle (regulated among other things by progesterone and prostaglandins) may control lung function at birth is strengthened by the fact that RDS can be provoked by progesterone in the rabbit and that fatty acids and prostaglandins are abnormal in human RDS.

Female↗
PubMed1980

Biochemical characterization of peritoneal fluid in women during the menstrual cycle.

Peritoneal fluid was collected at laparoscopy in women during the menstrual cycle and was assayed for protein and steroid hormone content. The total protein concentration in peritoneal fluid and the concentrations of the steroid hormone-binding proteins, transcortin and sex hormone-binding globulin, the polypeptide hormones, LH, FSH, and PRL, correlated with the plasma concentration but were lower; they were, respectively, 68%, 71%, 68%, 42%, and 34% of the plasma concentration. The concentrations of steroid hormones secreted by the ovary, i.e. 17 beta-estradiol, progesterone, androstenedione, and testosterone, were always equal or higher in peritoneal fluid than in plasma. In contrast, the concentrations of cortisol, a nonovarian steroid hormone, was 40% lower in peritoneal fluid than in plasma. No cyclic variations were observed in the peritoneal fluid concentrations of androstenedione and testosterone, two steroid hormones secreted by the stromal component of the ovary. On the contrary, the concentrations of 17 beta-estradiol and progesterone secreted by the follicular apparatus of the ovary increased sharply in peritoneal fluid after ovulation, reaching values of 44000 pg/ml and 3000 ng/ml, respectively. They declined progressively, whereas in plasma, peak concentrations were achieved only in the midluteal phase. In conclusion, the concentrations of 17 beta-estradiol and progesterone are much higher in peritoneal fluid than in plasma for at least 1 week after ovulation. We suggest that the secretion of the early, not yet vascularized, corpus luteum is directed preferentially toward the peritoneal cavity, creating a specific hormonal environment for the released oocyte and the oviduct.

Ascitic Fluid↗
PubMed1981

Lack of specificity of cortisol determinations in human urine.

The specificity of 7 different binding proteins (4 antibodies and 3 transins) was investigated in human urine. Pregnant and nonpregnant urine samples were extracted and chromatographed, and values were compared before and after chromatography. Without chromatography, all methods grossly overestimated the amount of cortisol present. Four methods gave higher values than the other 3 even after chromatography, possibly due to cross-reactivity with 20-dihydrocortisone which coelutes in part with cortisol. Interference also occurred in both the less polar and the more polar regions of the chromatograms with all assay systems. Values for a series of 20 urines were closely similar for the RTAs but widely divergent for the RIAs. Close correlations were found for all of the RTAs with each other and with the RIAs if simple methylene chloride extraction was used. A high degree of correlation was also found between extracted and unextracted urine values in the 4 systems studied. Cortisol values by RTA (dog transcortin) after chromatography on Sephadex LH-20 gave mean values of 20.5 +/- 9.7 microgram/day in men, 14.0 +/- 5.7 micrograms/day in cycling women, and 38.0 +/- 24.5 micrograms/day in women in late pregnancy (n = 6 in each group). It is concluded that there is no simple practical method currently available for true cortisol in urine, but that the measurement of adrenal corticoids in urine can afford an accurate reflection of adrenocortical function provided there is no gross metabolic abnormality present and that the normal range is carefully established for each particular method used.

Child↗
PubMed1981

Binding of steroids by proteins in follicular fluid of the human ovary.

Steroid-protein interactions were studied in the antral fluid of preovulatory follicles of the human ovary. Two high affinity binding systems are described. These steroid-binding proteins do not differ from those identified in the plasma of women (transcortin and sex binding protein), as indicated by similar specificity, binding affinity, and electrophoretic pattern. Their concentrations in the fluid are either similar to or lower than those in plasma. Since the steroid concentrations in antral fluid are approximately 20- to 100-fold higher than the binding capacities of the specific steroid binders, the buffer role that many authors attribute to the proteins which bind steroids is unlikely in antral fluid.

Body Fluids↗
PubMed1983

Prednisolone disposition and protein binding in oral contraceptive users.

Combined estrogen-progestogen oral contraceptives (OC) have been shown to alter the metabolism of certain drugs, including corticosteroids, as well as affect circulating protein concentrations. To assess these effects with regard to prednisolone, the pharmacokinetics and protein binding of this steroid were evaluated in eight female OC users and compared with results from eight male and five female non-OC users. All volunteers received 40 mg prednisolone, iv, and steroid concentrations were measured by high pressure liquid chromatography. Plasma clearance of total prednisolone in females on OC was 96 +/- 9 (SD) ml/min X 1.73 m2, significantly (P less than 0.001) lower than those in both male and female controls (205 +/- 46 and 187 +/- 22 ml/min X 1.73 m2). The prednisolone half-life and mean residence time were longer, while the steady state volume of distribution was smaller for OC users. Unbound prednisolone was measured by equilibrium dialysis, and pharmacokinetic and protein binding parameters were calculated from free prednisolone concentrations. A significantly higher (2-fold) concentration of transcortin was found in OC users. Evaluation of free prednisolone parameters showed a significantly lower clearance and decreased volume of distribution, without alteration of the mean residence time for the OC users. Dual OC effects on binding and elimination of prednisolone occur with the net result of a 2-fold increase in the area under the free concentration-time curve, indicative of a marked reduction in the biotransformation rate of the steroid.

Adult↗
PubMed1981

Oestrogen-like effects of tamoxifen on the concentration of proteins in plasma.

The concentrations of 11 plasma proteins were determined by electroimmunoassay in 6 female and one male patient before and after treatment for 1-4 months with tamoxifen (30 mg/day) for advanced cancer. The concentrations of transcortin, sex hormone binding globulin, pregnancy zone protein, apolipoprotein AI and thyroxine binding globulin increased significantly. The concentrations of orosomucoid and haptoglobin decreased significantly. The concentration of albumin, transferrin, prealbumin and retinol-binding protein showed no significant change. The changes after treatment with tamoxifen were thus similar to those which occur after the administration of oestrogens or during pregnancy although they were quantitatively less pronounced. There were also differences in the pattern of change between treatment with tamoxifen and during pregnancy. There was no apparent relationship between response to treatment and changes in concentration of plasma proteins.

Adult↗
PubMed1988

Ethinylestradiol and desogestrel, alone or in combination with two doses of estriol. Effects on plasma proteins.

Nineteen fertile women were treated with three differently composed oral contraceptives in a cross-over study and were randomly allocated to begin with one of the three preparations. The tablets contained 0.030 mg ethinylestradiol +0.15 mg desogestrel alone (A) or in combination with either 0.5 mg estriol (B) or 2 mg estriol (C). After two treatment cycles on each preparation, blood samples were obtained and analysed for ceruloplasmin, SHBG, prealbumin, transcortin and thyroxine-binding globulin. No differences were found in the induction of liver protein synthesis. It was concluded that the addition of estriol in doses of 0.5 or 2 mg did not influence the effects induced by ethinylestradiol.

Adolescent↗
PubMed1975

[Hydroxycorticosteroids and the binding capacity of transcrotin in sarcoma 45].

In sarcoma 45 growth the concentration of all fractions of 11-oxycorticosteroids (11--OCS) was found to be increased. Maximum increase in concentration of total and bound 11--OCS was noted on the 7th and 10th day after transplantation. The content of total and bound 11 -- OCS on the 15th and 20th day of tumor growth was close to control values, however, the concentration of free 11 -- OCS exceeded the control level. At the 30th day of the experiment the values of total and bound 11 -- OCS were reliably decreased. While the free hormone content was within control limits. In a progressing malignant growth the binding capacity of transcortin is reduced up to 18.5% (the 30th day of the experiment) that makes 25% of the control value. The content of bound exogenic corticosterone in vitro ranged from 7.7 to 45.2 Mg% in the process of sarcorna 45 growth.

11-Hydroxycorticosteroids↗
PubMed1975

Rapid, specific assay for plasma cortisol by competitive protein binding.

We describe a modified competitive protein-binding method for assay of plasma cortisol. Plasma samples are deproteinized by dilution with an ethanol/phosphate buffer, followed by heating at 100 degrees C for 2 min. Horse serum is used as the source of transcortin. Free radioactivity is separated from the protein-bound component by partition into liquid scintillation counting within 60 min. The assay has better specificity and precision than a competitive protein-binding assay in which ethanol extraction and Florisil adsorbent are used, and results correlate well with those of a specific radioimmunoassay method.

Binding, Competitive↗