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Biomedical subjects

F Bayard

Publications and source records attributed to F Bayard.

At least 145 records · Page 8Linked to original sources
PubMed1976

Testosterone and dihydrotestosterone concentrations in plasma, epididymal tissues, and seminal fluid of adult rats.

The concentration of testosterone (T) and 5alpha-dihydrotestosterone (DHT) in plasma, seminal fluid, and epididymis of male Wistar rats have been determined by radioimmunoassay. The DHT/T ratio rose from 0.1 in blood to 1 in testicular fluid and 4 in epididymal fluid. This ratio is 2 in tissues of "caput" epididymis and 1 in "cauda" epididymis. These data indicate a transformation of T to DHT in the epididymal tissue, particularly at the "caput" level.

Animals↗
PubMed1975

[Estradiol and progesterone receptors in human endometrium during the menstrual cycle].

The concentrations of estradiol and progesterone receptors are measured in the cytoplasmic and nuclear fractions of endometrial samples obtained by biopsy throughout the menstrual cycle. The standardized micromethod accounts for the sites occupied by endogenous hormones and for interference by androgen receptors and plasma binding proteins. In normal women, the cellular concentration of estradiol receptor increases early in the cycle and decreases steadily after ovulation. The progesterone receptor is maximum between the 10th and 15th day of the cycle and decreases during the luteal phase. The nuclear/cytoplasmic ratios of both receptors follow the variations of circulating hormones. These data constitute a new basis for physiopathological and pharmacological investigations on the hormonal control of the human uterus.

Biopsy↗
PubMed1975

Endometrial progesterone concentrations during the menstrual cycle.

Endometrial progesterone concentrations have been determined during the menstrual cycle and compared to plasma progesterone and estradiol-17 beta concentration. There is a good relationship between endometrial and plasma progesterone concentrations but none between endometrial progesterone and estradiol-17 beta concentration.

Corpus Luteum↗
PubMed1975

Motility of the oviduct and uterus of the cow during the oestrous cycle.

Recordings of electrical activity of the oviduct and uterus were obtained during three oestrous cycles in cows fitted with an extra-cellular multi-electrode assembly. The stages of the cycle were identified by the appearance of the cervico-vaginal secretions and changes in the peripheral plasma level of progesterone were determined by radioimmunoassay. A gradual transition from local non-propagating electrical activity to propagating electrical activity with increase in the duration of contractions and then of their amplitude occurred 48 hr before the onset of oestrus. The transition coincided with a rapid decrease in progesterone level from 5 to 10 ng/ml to less than 0-1 to 0-4 ng/ml. This phenomenon was recorded from all uterine electrode sites, but was most marked at the uterotubal junction. Two days before oestrus, trains of potentials and bursts of activity became progressively grouped, apparently randomly, into prolonged phases in the distal portion of the oviduct and over the entire myometrium. During oestrus, the phases of activity became synchronized at these sites and both their amplitude and frequency reached a maximum. The strength but not the frequency of the phases diminished progressively 3 days after oestrus, followed by relative inactivity. The last remaining zone of activity was the uterotubal junction. During oestrus, the activities of the oviduct and the uterus were modified by oxytocin and adrenaline, the effect of the former being more marked on the uterus and that of the latter on the oviduct.

Animals↗
PubMed1975

[Role of ACTH in regulation of aldosterone secretion].

During the nycthemeral cycle, ACTH modulated the aldosterone production and increases plasmatic level at the end of night. The chronic stimulant effect of angiotensin II is a permissive factor of ACTH influence on aldosterone formation.

Adrenocorticotropic Hormone↗
PubMed1975

Testicular function in XYY men.

A previous survey of 48 subjects with XYY chromosome complement showed a wide scatter of values for plasma concentration of testosterone and luteinizing hormone (LH). To account for this scattering and in view of the impulsive behavior often attributed to XYY subjects, it was postulated that paroxysmal activity in the cerebral cortex produced paroxysmal stimulation at the level of the hypothalamus. To investigate this possibility, plasma concentrations of testosterone, dihydrotestosterone, follicle stimulating hormone (FSH), and LH were determined on seven consecutive days in four XYY subjects and five XY control men as well as bimonthly for four months in two XYY detainees and three XY control detainees. The variability of plasma androgen and gonadotropin levels in XYY subjects was similar to that of XY control men. The results thus do not support the above hypothesis as an explanation of the widely scattered plasma androgen values in XYY individuals. The "XYY syndrome" is probably heterogeneous and includes a number of patients with some degree of hypogonadism. Testicular biopsy, sperm count, and meiotic studies were carried out in eight XYY men. In one case the meiotic study showed two Y-chromatin bodies. Results of these various investigations support the diagnosis of maturation arrest of the germ cells with consequent oligospermia. Low fertility is therefore expected to be frequent among XYY subjects, although when fertilization does occur, it can result in normal XY or in XYY infants.

Adolescent↗
PubMed1975

[Plasma concentrations of LH and of sex steroids during the normal menstrual cycle and during contraceptive treatment].

The authors have studied the long-term effects of combined oestrogen-progestogen on the secretion of gonadotrophins and on ovarian function. Estimation of the radio-immune levels of the plasma concentrations of the pituitary luteinizing hormone (LH), of oestradiol (E2), of progesterone (P) and of 20 alpha hydroxyprogesterone (20 alpha OHP) and of testosterone (T) served as a base for this study. A test cycle and 8 cycles in which a combination of 50 micrograms of ethinyl-oestradiol and 0.5 mg of norgestrel were administered were studied in 4 normal volunteer women. A pituitary stimulation test using 50 micrograms of gonadotrophin "releasing factor" (LH-RH) was given during the 7th cycle. Ovarian stimulation using human menopausal gonadotrophins (HMG) was given during the 8th cycle of treatment in 3 of the women and in 3 other subjects. Pituitary secretion of LH and ovarian secretion of E2 and P are partially inhibited. Pituitary response to the injection of LH-RH stays normal but 5 out 6 patients had no response to stimulation by gonadotrophins. These results allow us to conclude that the lowering of production of gonadotrophins during treatment with combination oestrogen and progestagens is responsible for inhibition of ovarian activity, and that there is a delay before the latter respond to stimulation by either endogenous or exogenous gonadotrophins.

Adult↗