Search PubMed⌕ Search

Biomedical subjects

F Bayard

Publications and source records attributed to F Bayard.

At least 127 records · Page 7Linked to original sources
PubMed1979

17 beta-hydroxysteroid dehydrogenase in monkey endometrium: characterization of enzyme activity, and effects of estradiol alone or in combination with progesterone.

17 beta-Hydroxysteroid dehydrogenase (HSD) was studied in endometrium removed surgically from intact female monkeys in the luteal phase of the menstrual cycle. Also castrated monkeys (N=20) implanted with estradiol (E2) and progesterone (P) in silastic capsules were used to investigate the hormonal dependence of this enzyme in endometrium. The activity was characterized by an optimal pH between 9 and 10, a Km for E2 of 14.2 x 10(-6)M, a Vmax of 0.9 x 10(-6)M x min-1 in Tris-HCl buffer 50 mM pH 9. Using these conditions, we found linearity with time and protein concentration. Subcellular fractionation of endometrial homogenate showed a maximal activity in the 105,000 x g ultracentrifugation microsomal pellet and a very low activity in cytosol. HSD activity increased slightly, but distinctly, with E2 capsules alone, and a marked HSD stimulation (10 fold) occurred after P administration in combination with E2. There are strong similarities between this enzyme and the one described in human endometrium.

17-Hydroxysteroid Dehydrogenases↗
PubMed1979

Estrogen and progestin regulation of the progesterone receptor concentration in human endometrium.

The concentration of the progesterone receptor (PR), both cytosol and nuclear, has been measured in the endometrium of 31 normal menstruating women during the 2 phases of their menstrual cycle and compared with the plasma 17 beta-estradiol and progesterone concentrations. There was no relationship between PR concentrations and the plasma steroid levels when the 2 phases of the cycle were considered; however, a statistically significant correlation (r = 0.70; P less than 0.005) was observed between PR concentration and plasma 17 beta-estradiol when only the follicular phase was considered. PR was then measured in the endometrium of 14 postmenopausal patients treated with ethinylestradiol at increasing doses with or without association of chlormadinone acetate. Ethinylestradiol was shown to increase PR concentration (P less than 0.05), and chlormadinone acetate was found to prevent this increase. These data suggest that in humans, as in other mammalian species, the endometrial PR concentration is under estrogen and progestin control.

Chlormadinone Acetate↗
PubMed1979

Oestrogen and progesterone receptor concentrations in human endometrium during gestation.

The concentrations of endometrial oestrogen and progesterone receptors, both in cytosol and in nuclei, have been studied at 8--10 weeks and at 38--40 weeks of gestation. At these two periods the concentration of oestrogen receptors is comparable with the concentration observed during the late secretory phase of the menstrual cycle. At 8--10 weeks of gestation, concentration of progesterone receptors is also comparable with the concentration observed during the secretory phase of the menstrual cycle, but at term there is a significant increase (P less than 0.05) and the concentration is then comparable with the concentration observed in the pre-ovulatory period of the menstrual cycle. The receptor binding sites are always predominantly found in nuclei and the increase in progesterone nuclear receptor at term suggests that in man the progesterone withdrawal is not a necessary step in the mechanism of uterine activation during parturition as it is in other species.

Cell Nucleus↗
PubMed1979

Androgen receptors in the rat epididymis and their hormonal control.

The concentrations of cytoplasmic receptor sites for androgens in the caput, corpus and cauda epididymidis, and the effect of ligation of the efferent ducts and testosterone treatment after bilateral castration on the concentration of receptors in the caput have been measured. Androgen receptors in the ventral prostate have been measured in the same animals for comparison. The caput has the highest concentration of receptor sites, the corpus the lowest. The ligation of the efferent ducts has no effect on this concentration which is dependent on testicular androgens. The present data do not yet allow explanation of the differential response of the different regions of the epididymis and of the other accessory glands to the administration of androgens.

Animals↗
PubMed1978

5alpha-Reductase and 3alpha-hydroxysteroid oxidoreductase enzyme activities in epididymis and their control by androgen and the rete testis fluid.

The 5alpha-reductase and 3alpha-hydroxysteroid oxidoreductase enzyme activities have been measured in epididymal tissues and the control of these activities by androgens and the rete testis fluid appreciated. The highest 5alpha-reductase enzyme activity was found in the caput, the lowest in the corpus epididymidis. Androgens have a positive control on the 5alpha-reductase but no effect on the 3alpha-hydroxysteroid oxidoreductase activity. Ligation of the efferent ducts decreased significantly both enzyme activities in the caput but not in the corpus or in the cauda epididymidis.

3-Hydroxysteroid Dehydrogenases↗
PubMed1978

Cytoplasmic and nuclear estradiol and progesterone receptors in human endometrium.

Estradiol and progesterone receptors have been characterized in normal human endometrial biopsy samples. The cytosol and nuclei were prepared from 150-250-mg samples, either processed immediately or kept in liquid nitrogen. The total concentration of estradiol-and progesterone-binding sites (available or occupied with endogenous hormone) were measured in both fractions. Results were best expressed in femto-moles per mg DNA, or in sites per cell, assuming an even distribution of receptor throughout the endometrial samples. The contribution to total binding of non-saturable binding components and of plasma proteins (transcortin or sex steroid-binding protein) was taken into account. Measurements were obtained in more than 300 patients, among whom 54 had completely normal menstrual cycles on the basis of clinical, hormonal, and histological features. Total estradiol and progesterone receptors were highest in the late proliferative phase (about 8,000 and 12,000 sites/cell, respectively) and were very significantly lower in the late secretory phase. During the proliferative phase, estradiol receptors were increased only in the nuclear fraction, whereas progesterone receptors were increased mainly in the cytoplasm. In the early luteal phase, estradiol and progesterone receptors decreased in the cytosol, whereas they remained high in the nuclei. Both receptors were at their lowest level in cytosol and nuclei in the late secretory phase. The changes of total estradiol and progesterone receptor sites and of their respective subcellular distributions seem to depend upon the plasma levels of both hormones and to follow the same cause and effect relationships as those demonstrated experimentally in laboratory animals.

Cell Nucleus↗
PubMed1978

Measurement of the corticosteroid-binding globulin, progesterone, and progesterone "receptor" content in human endometrium.

The corticosteroid-binding globulin (CBG) content has been determined in cytosols prepared from human endometrium taken at different phases of the menstrual cycle, at 8-10 weeks gestation, and during treatment with an oral contraceptive. The data were compared to the progesterone "receptor" and the progesterone concentration in the same tissue extracts. The plasma contamination was estimated by the serum albumin content. It was observed that CBG is a constant contaminant of the endometrial cytosols. All of the CBG content can be considered to be of plasma origin. The cytoplasmic progesterone "receptor" content is between 21-33% of the CBG concentration during the menstrual cycle and is only 1% during pregnancy. The cytosol progesterone concentration is much higher in endometrium than would be expected from the plasma contamination and the level of the progesterone "receptor".

Cell Nucleus↗
PubMed1978

[Presence of nuclear triiodothyronine (T3) receptors in mouse fibroblasts].

The present preliminary data obtained from intact fibroblasts of adult mice (polyploid stem L 929) suggest that this cell system possesses high-affinity and saturable nuclear binding sites for triiodothyronine. As estimated by the Scatchard analysis, the equilibrium dissociation constant is approximately 2 X 10(-10) moles, the maximal binding capacity is about 2 000 sites for T3 per cell nucleus.

Animals↗