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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Steroids have been coupled to pyrimidines to give potentially target-specific anti-tumor agents. We report here on the molecular structures of two such adducts. 21-(1H-uracil-1-yl)-pregn-4-ene-3,20-dione and 21-(1H-thymin-1-yl)-pregn-4-ene-17 alpha-ol-3,20-dione. The structures of these have been determined by X-ray crystallographic techniques. The uracil substituent of the former compound is observed to be oriented below the alpha-face in the plane of the steroid skeleton. In contrast, upon introduction of a 17 alpha-hydroxyl group, as in the latter compound, the base substituent is found to be in a perpendicular orientation bent towards the beta-face of the steroid skeleton. In the uracil derivative the bases stack between steroid portions of other molecules. In the thymine adduct this does not occur. Only steroid--steroid stacking is observed. The molecule conformations are correlated with the differences in receptor affinity for these two steroid adducts.
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PMID:The structures of two potential antitumor steroid--base adducts. 686 11

The translocation of progesterone receptor from the cytosol into the nucleus was studied under "in vivo" and "in vitro" conditions in the uteri of guinea pig fetuses exposed to progesterone or a synthetic progestin, R5020. Progesterone treatment of estrogen-primed fetuses leads to a rapid (before 1h) transfer of cytosol progesterone receptor into the nucleus which is, however, short-lived (less than 3h). A rapid decrease in the retention of the estrogen receptor in the nucleus also occurs. In the "in vitro" incubations of whole fetal uteri, translocation of progesterone receptor is temperature-dependent and specific for progesterone and R5020; estradiol and cortisol have no effect. Putative progesterone receptors can also be induced in explants of fetal guinea pig uteri in organ culture which translocate from the cytosol into the nucleus under the same "in vitro" conditions as in whole uteri. Fetal uterine progesterone receptor, either stimulated "in vivo" by estrogen-priming or induced in organ culture, translocates from the cytosol into the nucleus and this process seems to be accompanied by a decrease in retention of the estrogen receptor in the nucleus which appears to be the mechanism by which progesterone antagonises estrogen action in fetal guinea pig uterus.
Steroids 1982 Apr
PMID:Characteristics of the nuclear translocation of progesterone receptor in fetal guinea pig uterus "in vivo", "in vitro" and in organ culture. 689 Nov 22

The synthesis, secretion and metabolism of progesterone have been examined in six human teratoma-derived cell lines with the objective of determining if they exhibit trophoblast-related or other specific steroidogenic functions. Progesterone was synthesised in nanogram amounts (per 10(6) cells/day) by the cell line SuSa, as measured by radioimmunoassay, and in lesser amounts by line LICR-LON HX-39. Lines Tera 1, Tera 2, T3B1 and PA-1 did not secrete detectable progesterone. All teratomas, however, metabolized added progesterone in microgram amounts (per 10(6) cells/day). In all cases the major metabolite was a polar compound, identified by reversed phase HPLC, TLC and GC-MS as 3 beta, 6 alpha-dihydroxy-5 alpha-pregnan-20-one. This pattern of metabolism was not confined to the teratomas as equivalent amounts of this polar metabolite were formed by cultures of adult differentiated human epithelial and fibroblast cells. When progesterone and its metabolites, separated by HPLC, were included in the estimation, the delta 5-3 beta-hydroxysteroid dehydrogenase-isomerase activity of SuSa was equivalent to 47ng pregnenolone (3 beta-hydroxy-5-pregnen-20-one) metabolised/mg protein/day, that of HX-39 to 9ng/ml protein/day and those of other teratomas to less than 3.5ng/mg protein/day.
Steroids 1981 Dec
PMID:Progesterone synthesis, secretion and metabolism by human teratoma-derived cell-lines. 695 May 73

There is indirect evidence that cortisol synthesis in the fetal rhesus monkey adrenal gland is limited at Day 135 of gestation but increases thereafter. This study was conducted to ascertain whether a reduced synthetic capacity is caused by a deficiency in 17-, 21- or 11-hydroxylase activity. For the sake of comparison 11- and 21-hydroxylases were also estimated in adult adrenals. 11-, 21-Hydroxylases were measured in the entire adrenal by the oxidation of NADPH by mitochondria and microsomes, respectively. 17-Hydroxylase was evaluated in outer and inner regions of the fetal gland by the formation of [3H]17-hydroxyprogesterone, -11-deoxycortisol, -cortisol and -androstenedione from [3H]progesterone. The maximum velocity of both the 11- and 21-hydroxylase was similar in fetal and adult glands indicating that corticoid formation in the fetus is not constrained by levels of these enzymes. [3H]Progesterone was extensively metabolized to -17-hydroxyprogesterone, -androstenedione, -11-deoxycortisol and -cortisol by homogenates from both regions of the fetal adrenal. The ratio of [3H]-cortisol to [3H]11-deoxycortisol was consistently higher in incubations of the inner glandular area. Together, these findings indicate that 17-hydroxylase is also active at Day 135 and that the 11-hydroxylase may be more concentrated in the fetal cortex. These data suggest in addition that the restriction in cortisol formation occurs at a step prior to the metabolism of progesterone to cortisol.
Steroids 1982 Oct
PMID:Corticoid formation by the monkey fetal adrenal: evaluation of 17-, 21-, and 11-hydroxylase activities. 717 Jul 54

Injection of estradiol to ovariectomised rats caused significant increase in the activity of glucosamine 6-phosphate synthase of uterus. Progesterone did not cause any increase in the activity of the enzyme; however, it antagonised the effect of estradiol. It was observed that the enzyme is predominantly localised in the endometrium of uterus.
Steroids 1981 May
PMID:Effect of estradiol and progesterone on glucosamine 6-phosphate synthase in the uterus of rat. 719 98

The purpose of this study was to determine the short-term effects of progesterone action on estrogen receptor (Re) levels in the rat uterus. Ovariectomized, adrenalectomized rats were maintained on subcutaneous Silastic implants containing crystalline estradiol. Progesterone treatment with serum estradiol maintenance caused a rapid decrease (within 4 h) of total Re, attributable to loss of nuclear Re without a significant change in cytosol Re levels. Removal of estradiol implants resulted in an increase in total Re and cytosol Re at all time periods studied without a significant decrease in nuclear Re until 8 h. Combined estradiol withdrawal and progesterone treatment resulted in lower total Re levels and a more rapid decrease in nuclear Re than with estradiol withdrawal alone. These results demonstrate that progesterone rapidly and selectively decreases nuclear Re levels in rat uterus and suggest that this process is not dependent on cytosol Re or serum estradiol levels.
Steroids 1981 Apr
PMID:Progesterone regulation of estrogen receptor in the rat uterus: a primary inhibitory influence on the nuclear fraction. 724 90

The effect of progesterone on transcription was investigated in the uterus of the ovariectomized rat. Progesterone rapidly depressed both RNA polymerase A and B activities for up to 6 h after steroid administration. Both enzyme activities returned to control values 24 h after steroid treatment. In contrast, in the estrogen-primed rat uterus, progesterone was capable of stimulating RNA polymerase B activity 30 min after hormone treatment. The cellular entities or mechanisms which progesterone uses to alter transcription in cell nucleus remain to be determined.
Steroids 1981 Nov
PMID:The effect of progesterone on RNA polymerases in the rat uterus. 732 84

Progesterone-BSA (bovine serum albumin) conjugates which contain up to 47 steroid molecules linked to a BSA molecule have been prepared by the activated ester method, the conjugation step being carried out in reversed micellar solutions of sodium di(2-ethylhexyl) sulphosuccinate (AOT) in octane. The number of incorporated steroid molecules increases on passing to increased water/AOT ratios at the given activated steroid/BSA ratio. The results show that the reversed micellar medium would be useful for preparation of conjugates of hydrophobic steroids with proteins in respect to simplicity and ease in obtaining conjugates with high steroid/protein ratios.
Steroids 1993 Nov
PMID:Preparation of conjugates of progesterone with bovine serum albumin in the reversed micellar medium. 750 59

Two follicular compartments, granulosa (G) and theca interna (T) cells isolated from porcine ovaries were cultured alone or in co-culture (GT). Cells were grown as monolayers in a control medium without hormone and in a media supplemented with arginine-vasotocin (AVT) at a concentration of either 10(-7)M or 2 x 10(-7)M. Progesterone (P4), estrogen (E2) and androgen (A) concentrations in the culture media were taken as measures of the effect of AVT on the function of follicular cells. Steroids were analysed by radioimmunoassay. AVT action in this culture system was expressed as a decrease in progesterone secretion by cultures of granulosa cells alone, and especially as a change in the pattern of estradiol and androgen secretion by co-cultures. Control T and G cells cultured alone secreted small amounts of A (238.0pg/10(5) cells, 27.3pg/10(5) cells, respectively), and E2 (272.5pg/10(5) cells, 10.6pg/10(5) cells, respectively) while in co-culture these two cell types interacted and the result of this positive interaction was a significant increase in secretion of these two steroids (941.0pg/10(5) cells androgen secretion and 854.1pg/10(5) cells estradiol secretion). This phenomenon is similar to that observed in the intact follicle in vivo. AVT introduced to the culture medium impaired the effect of this positive interaction of mixed G and T cells on the production of high levels of E2 and A by untreated co-cultures.
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PMID:Evidence for inhibition of steroid hormone secretion by arginine vasotocin (AVT) in tissue culture of isolated ovarian follicular cells. 784 65

The secretion of progesterone and 20 alpha-dihydroprogesterone (20 alpha-DHP) during the estrous cycle and the effects of prostaglandin F2 alpha (PGF2 alpha) and 20 alpha-DHP on the secretion of these two steroids during the midluteal phase in goats were studied. The mean progesterone concentration in the peripheral plasma was extremely low (< 0.01 ng/mL) on the day of estrus. The concentration increased to a maximum (7.80 ng/mL) on about day 10 after estrus, and decreased rapidly during the last 3 days of the cycle. The plasma concentration of 20 alpha-DHP also was low (0.86 ng/mL) on the day of estrus, but increased gradually after estrus and decreased gradually in the last 5 days of the cycle (to 3.22 ng/mL). The ratio of progesterone to 20 alpha-DHP was > 1 after day 2 of estrus, but decreased and fell to < 1 during the last 3 days of the cycle. An injection of 3 mg of PGF2 alpha decreased the secretion of progesterone within 30 min, but affected the secretion of 20 alpha-DHP little until 2 h. The ratio of progesterone to 20 alpha-DHP fell to < 1 after 24 h. Three of the five goats given such an injection came into estrus within 2 days, and the other two came into estrus within 3 days. An injection of 15 mg of 20 alpha-DHP did not affect progesterone secretion or the estrous cycle length. These results indicate that in the goat after estrus, there is much 20 alpha-DHP in the peripheral plasma. Progesterone may be catabolized to the biologically inactive steroid, 20 alpha-DHP, during luteolysis.
Steroids 1994 Dec
PMID:Secretion of progesterone and 20 alpha-dihydroprogesterone during the estrous cycle in goats. 790 Jan 64


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