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Results for “PROGESTATIONAL HORMONES”

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At least 253 records · Page 14Linked to original sources
PubMed1987

Differences in the association of the progesterone receptor ligated by antiprogestin RU38486 or progestin ORG 2058 to chromatin components.

We assessed the hypothesis that due to variations in the conformation of the progesterone receptor induced by the antiprogestin RU38486 compared to the progestin ORG 2058, differences may result in the association of the receptor with some of the chromatin components. The physical properties of the receptor-bound chromatin fragments released by micrococcal nuclease digestion were characterized by sucrose gradient sedimentation and by gel filtration on Agarose A-1.5m or Agarose A-5m columns. The nuclear fraction was isolated from T47D cells previously exposed to 0.1 microM [3H]RU38486 or 0.1 microM [3H]ORG 2058. Micrococcal nuclease digestion solubilized two receptor forms sedimenting at 4.4 S and 6.3 S for the antiprogestin bound receptor and only one receptor at 4.4 S for the progestin ligated receptor. High-salt buffer dissociated either the antiprogestin or the progestin-bound receptor to smaller receptor forms sedimenting at 3.5 S. Chemical cross-linking with the cross-linker 2-iminothiolane of the micrococcal nuclease solubilized receptor forms resulted in 6.7-S and 4.4-S forms sedimenting on 0.4 M KCl gradients for the antiprogestin and progestin ligated receptors, respectively. Stokes radii of 7.3 nm and 6.4 nm were determined by gel filtration in 0.4 M KCl for the 6.7-S and the 4.4-S receptor forms, respectively. Using the sedimentation coefficient and the Stokes radius, molecular weights of 202,000 and 116,000 were calculated for the antiprogestin and progestin ligated receptors. We conclude that the micrococcal nuclease solubilized antiprogestin ligated receptor is associated with additional or different chromatin components compared to the progestin bound receptor.

Cell Line↗
PubMed1979

The mechanism of coronary artery spasm: roles of oxygen, prostaglandins, sex hormones and smoking.

A reduced oxygen supply to the heart causes coronary vasodilatation in the first instance. But if the hypoxia is severe or prolonged, the dilatation passes off and coronary vasospasm develops leading to a vicious circle with a further reduction of myocardial oxygenation. The spasm is associated with increased outflow of prostaglandin (PG)-like material and can be prevented or reversed by inhibitors of PG synthesis such as indomethacin or antagonists of PG action such as chloroquine. The spasm does not appear to be caused by thromboxane (TX) A2 since selective inhibitors of TXA2 synthesis enhance the hypoxic spasm and by themselves can cause spasm even in oxygenated hearts. The mechanism may be related to loss of negative feedback control of the PG pathway by TXA2. Oxygen may enhance TXA2 production and reduce formation of vasoconstrictor PGs, while smoking, because of the formation of carboxyhaemoglobin, may have the opposite effect. Oestradiol and testosterone do not influence the hypoxic spasm but progesterone at physiological concentrations blocks it completely. Progesterone may be the protective female hormone and the increased susceptibility to myocardial infarction in women on oral contraceptives may be related to reduced formation of endogenous progesterone.

Coronary Circulation↗
PubMed1991

Idiometric assay, the third way: a noncompetitive immunoassay for small molecules.

A novel, noncompetitive immunoassay applicable to the measurement of small molecules including ovarian steroids is described. Using monoclonal antibodies with the ability to recognize both beta-typic and alpha-typic binding sites, a new simplified, sensitive, and specific immunoassay system has been developed. The initial work of this development is presented, along with preliminary results for a novel immunoassay for estradiol.

Antibodies, Anti-Idiotypic↗
PubMed1977

Uterine blood flow and its distribution after chronic estrogen and progesterone administration.

The rates and distributions of uterine blood flow (UBF) were measured in conscious castrated ewes during estradiol, progesterone, and combined-hormone regimens. Supplemental progesterone decreased the magnitude of UBF observed on estradiol alone. Progesterone favored distribution of UBF to the uterine caruncles and estradiol favored distribution to the myometrium and uterine cervix. Proportionate endometrial blood flows were similar on all hormone regimens. These observations suggest that estradiol secretion may not be responsible for the definitive increase in UBF observed during ovine pregnancy.

Animals↗
PubMed1987

A new delivery system for contraceptive steroids.

Long-acting forms of contraception that take advantage of the tissue compatibility of silicone rubber, a polymer of dimethylsiloxane, have been developed. The most advanced type of subdermal contraceptive capsule contains about 36 to 40 mg of levonorgestrel and is 30 mm in length and 2.4 mm in diameter (Norplant). The set of six implants is placed under the skin of the upper arm with a 10-gauge trocar with the use of a local anesthetic. The basis for the antifertility effect of these implants is continuous, low-dose progestogen therapy without the use of estrogen. The capsules release a total of approximately 39 micrograms of levonorgestrel each day. The blood progestogen level achieved through this microabsorption delivery system is 0.25 to 0.3 ng/ml. There is a sufficient supply of steroid in the capsules to maintain this blood progestogen level for 5 to 6 years. Since the capsules can be removed at any time, this contraceptive method is voluntarily reversible. The effectiveness of these subdermal implants has been evaluated in long-term studies that have progressed for well over 5 years. Therefore one clinic visit eliminates nearly 2000 days of concern over having to remember to take a pill on schedule. There has been sufficient experience to assure that fertility recurs promptly after removal of the subdermal implants.

Clinical Trials as Topic↗
PubMed1987

Antifertility actions of the progesterone antagonist RU 486 include direct inhibition of placental hormone secretion.

the antifertility effects of the potent antiprogestin RU 486 (mifepristone) during early pregnancy have been attributed to its blockade of progesterone receptors in the endometrium. Studies in cultured syncytiotrophoblasts have revealed an additional action of RU 486 at the placental level, where it impairs the production of human chorionic gonadotropin (hCG), human placental lactogen (hPL), and progesterone. RU 486 (10 nmol-10 mumol/l) attenuated the production of all three placental hormones, in a dose-related manner, and its effects on hCG and hPL were reversed by addition of exogenous progesterone. The specific inhibitory effects of RU 486 on placental hormone secretion indicate that its antifertility actions are attributable to competitive inhibition of progesterone action in the trophoblast as well as in the endometrium.

Abortifacient Agents↗
PubMed1988

Termination of early pregnancy by the 3 beta-hydroxysteroid dehydrogenase inhibitor epostane.

Progesterone is essential to sustain pregnancy in the first eight weeks. Its synthesis requires the enzyme 3 beta-hydroxysteroid dehydrogenase (3-HSD). We tested the efficacy of an orally administered 3-HSD inhibitor, epostane, in terminating unwanted early pregnancy. Fifty women in the fifth through eight weeks of pregnancy took epostane (200 mg orally every six hours) for seven days. By day 14, pregnancy had been terminated in 42 of the 50 patients (84 percent). Eight women (16 percent) did not abort and underwent dilation and curettage. Vaginal blood loss occurred on average on the third day of epostane treatment, and abortion on the fifth day. Two patients had incomplete abortions; one required a transfusion because of blood loss. Nausea was frequent (in 86 percent), but 76 percent of the participants concluded that epostane was preferable to dilation and curettage. The mean (+/- SD) pretreatment progesterone level (76 +/- 16 nmol per liter) decreased by day 7 (to 16 +/- 11 nmol per liter) and day 14 (to 10 +/- 9 nmol per liter) in those who aborted; levels of human chorionic gonadotropin also decreased from the mean at base line (73 +/- 72 kIU per liter) to 18 +/- 7 kIU per liter on day 7 and 9 +/- 5 kIU per liter on day 14. In those who did not abort after epostane treatment, progesterone levels decreased only slightly by day 7 (to 52 +/- 21 nmol per liter) and rose again (to 81 +/- 18 nmol per liter) by day 14. Among women who responded to epostane, normal menstrual periods had resumed by day 42 after the beginning of treatment in 72 percent. We conclude that epostane taken orally is an effective and safe method for the noninvasive termination of undesired early pregnancy.

3-Hydroxysteroid Dehydrogenases↗
PubMed1987

Nasal absorption of progesterone in women.

Absorption profiles were obtained from women following the administration of ointment containing 20, 30 and 40 mg of progesterone to the nasal mucosa. There were no significant differences in area-under-curves between groups receiving the drug in one nostril but when 40 mg doses were divided between two nostrils there was a significantly greater area-under-curve suggesting that the area of mucosa applied with the drug is more important than dosage.

Absorption↗
PubMed1989

Induction of abortion in early first trimester human pregnancy using epostane.

The role of epostane (Sterling Winthrop, Guildford, UK), a competitive inhibitor of the 3 beta hydroxysteroid dehydrogenase enzyme system (3 beta-HSD), as an abortifacient agent in early human pregnancy has been studied in 54 women. All were less than 49 days from their last menstrual period. Thirty were treated with 200 mg of epostane every 8 h for 7 days and 24 were given 200 mg every 6 h for 7 days. This caused a sustained reduction in circulating progesterone concentrations, a smaller fall in 17 beta-oestradiol and no effect on serum cortisol. Abortion occurred in 21 women (70%) in the lower dosage group and in 20 women (87%) in the higher dosage group. Abortion was incomplete in 6 of these 41 women. A worsening of pregnancy nausea and vomiting was noted by 66% of women in the first group and 84% in the second. There was no delay in the resumption of normal menstruation following abortion. This study confirms the potential of epostane as an effective inhibitor of ovarian and placental steroidogenesis and as a potent abortifacient agent in early human pregnancy.

Abortifacient Agents↗