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Biomedical subjects

C Robyn

Publications and source records attributed to C Robyn.

At least 91 records · Page 5Linked to original sources
PubMed1977

[Oestriol effect upon prolactinaemia in postmenopausal women (author's transl)].

Six postmenopausal women were treated at two ocasions with an oral dose of, respectively, 2 mg and 6 mg oestriol per day for 14 days; at least one month interval separated the two treatment periods. Blood was collected for prolactin measurement (homologous human radioimmunoassay) every other day during each treatment period as well as during a 14 days control period in the same subjects. Mean prolactin level during oestriol administration, regardless of the dose, was statistically not significantly different from that observed during the control period.

Administration, Oral↗
PubMed1977

[Neuroendocrine investigation of the follicular phase: spontaneous and after estrogen stimulation (author's transl)].

Estrogen stimulation on days 7, 8, 9 of the menstrual cycle induces disturbances of the usual clinical and hormonal patterns. Alpha rythm (8-12 Hz) variation curve, studied by mathematical analysis, is modified, and delayed ovulation happened at its nadir. It is concluded that EEG appears as a tool for clinical neuroendocrine correlations and that this preliminary study may indicate that this estrogen positive feedback is received at the neurovegetative level.

Alpha Rhythm↗
PubMed1976

Serum-prolactin in long-lasting lactation amenorrhoea.

Basal serum-prolactin concentrations were high until 15 months post partum in nursing mothers in Central Africa (Lwiro). They were significantly lower in menstruating than in amenorrhoeic nursing mothers. These results support the hypothesis that prolactin is involved in the long-lasting amenorrhoea which occurs in regions where breast-feeding is prolonged for up to 2 years after delivery.

Africa, Central↗
PubMed1976

Pituitary and extrapituitary effects of somatostatin in normal man.

The effects of synthetic linear somatostatin on basal circulating levels on several pituitary and pancreatic hormones, and of glucose and free fatty acids (FFA) were studied in 6 normal men after an overnight fast. A priming intravenous infusion of 250 mug of somatostatin in 18 sec was followed by a constant infusion of 500 mug over a period of 60 min. A decrease in plasma values of GH, prolactin, TSH, insulin and glucagon and in blood glucose was observed during somatostatin infusion, while FFA levels increased progressively. Plasma IRI and blood glucose increased rapidly when the somatostatin infusion was stopped, while FFA decreased progressively; GH, prolactin, TSH and glucagon remained low as compared to basal levels for one hour after the end of the infusion, i.e. until the end of the experiment. A slight but significant increase of LH and ACTH was observed after the end of the infusion.

Adrenocorticotropic Hormone↗
PubMed1976

Comparative immunoenzymatic localization of prolactin and growth hormone in human and rat pituitaries.

Twelve human and twelve rat pituitaries were stained by an immunohistochemical method using a rabbit anti-ovine prolactin serum, a rabbit anti-human growth hormone serum and a sheep anti-rabbit immunoglobulin serum conjugated with horseradish peroxidase. On the same pituitary section, growth hormone cells were stained brown by using 3-3'-diaminobenzidine as peroxidase substrate, and prolactin cells were stained purplish blue by using 4-chloro-1-naphtol. Growth hormone cells outnumbered prolactin cells, especially in human pituitaries where the proportion is at least 10:1. No cells containing both brown granules stained for growth hormone and blue granules stained for prolactin were found in any of the sections examined. In the fetal pituitaries, there was no apparent hypertrophy of the prolactin cells, although the circulating levels of the hromone are known to be as high in the fetus at term as in the mother and much higher than in nonpregnant women.

Adult↗
PubMed1976

Influence of low dose oestrogen on circulating prolactin. LH and FSH levels in post-menopausal women.

The effect on serum prolactin, LH and FSH levels of 25 mug ethinyloestradiol administered daily per os during 27 consecutive days was investigated in 5 post-menopausal women aged 52-78. Blood samples were collected before, during and after treatment. The hormones were assayed in serum by radioimmunological methods. Both LH and FSH decreased progressively and significantly from 120 and 115 mIU/ml before treatment to 52 and 51 mIU/ml, respectively after three weeks of oestrogen administration. Two weeks after interruption of treatment, LH (90mIU/ml) and FSH (112 mIU/ml) were significantly higher than during the last week of treatment. Mean prolactin level increased from 127 muU/ml before treatment to 237 muU/ml after 10 days of oestrogen administration (P less than 0.001). This increase was significant after 4 to 8 days and the levels remained about twice as high as the control values for the rest of the treatment period. Two weeks after interruption of treatment, serum prolactin had fallen (136 muU/ml) to the pre-treatment levels. Such results raise the question of possible effects of elevated levels of this hormone during long term oestrogen medication in post-menopausal women on the development of breast cancer.

Administration, Oral↗
PubMed1976

Effects of testosterone on gonadotrophin responses to synthetic LH and FSH releasing hormone (LRH) in normal men.

LRH tests were performed in 6 adult men with intravenous injections of 25 mug, before and one week after an intramuscular injection of 250 mg testosterone oenanthate (Testoviron Depot). One week after intramuscular injection of Testoviron the tonic secretion of LH was completely suppressed, but the reactivity or the reserve capacity of LH secretion, as tested by LRH, remained unchanged. In contrast, the tonic secretion of FSH and the reactivity of FSH secretion to LRH were both partly suppressed. Three months after the Testoviron injection, the basal levels of LH were still significantly lower than the control values, but the basal levels of FSH were identical to the control values. These data indicate that, in man, the feedback action of testosterone on gonadotrophin secretion could be exerted, at least for LH, at the hypothalamic level rather than at the pituitary level . No significant effects of LRH were noted on the circulating levels of growth hormone and sugar. There was a distinct rise in serum prolactin, which was occasionally significant, within 30 min after LRH injection; this is considered to be without physiological significance.

Adult↗
PubMed1976

Treatment of fibrocystic disease of the breast with a prolactin inhibitor: 2-Br-alpha-ergocryptine (CB-154).

In order to evaluate the importance of prolactin in the pathogenesis and clinical evolution of fibrocystic disease of the breast, serum prolactin levels were determined in 7 patients affected by this condition before and during treatment with a prolactin inhibitor, 2-Br-alpha-ergocryptine (CB-154). Serum prolactin levels were found to be low or normal before treatment. During treatment with CB-154 there was an improvement in all patients but 2. The results of the study do not allow any conclusion on the possible relation between serum prolactin levels and fibrocystic disease of the breast but they indicate that CB-154 may be useful for treating patients with this disorder.

Adolescent↗
PubMed1975

Gonadotrophin hormone releasing tests in women receiving hormonal contraception.

Gonadotrophin secretion by the pituitary was tested by i.v. injections of synthetic LH and FSH releasing hormone (LHRH) in five normal women between day 21 and day 25 of the luteal phase of the cycle, in twelve women receiving contraception with i.m. injection of medroxyprogesterone acetate and in eight women taking combined oral contraceptives of different varieties. Treatment with oral contraceptives led to a decrease or even to complete suppression of the response and possibly the reserve capacity of both LH and FSH secretions. Treatment with medroxyprogesterone acetate for several years lowered basal serum LH and FSH as did oral contraceptives but had much less effect on the responses to LRH. In long-term steroid contraception, progestogens alone seem to exert much less deleterious effect on gonadotrophin function than when used in combination with an oestrogen.

Adult↗
PubMed1975

Effects of glucocorticoids on pituitary hormonal responses to hypoglycemia. Inhibition of prolactin release.

The characteristics of pituitary hormonal responses to insulin-induced hypoglycemia were investigated in 16 normal men. In all subjects, levels of blood sugar fell below 35 mg/100 ml. A statistically significant increase in mean plasma levels of prolactin, ACTH, cortisol and growth hormone was observed. Prolactin levels increased in all subjects but one; individual peak values were 1.4 minus 8.4 times greater than base levels. The kinetics of prolactin, GH and ACTH responses were similar; in particular, the onset of release (25 min) of prolactin, GH and ACTH was similar. After dexamethasone administration, insulin tolerance tests wererepeated in a number of subjects using adequate amounts of insulin to achieve hypoglycemia equivalent to that obtained in the control experiments. The administration of 1 mg of dexamethasone the evening before the test suppressed basal levels of ACTH and cortisol and the ACTH-but not the cortisol-response to hypoglycemia. Both basal levels of prolactin and prolactin response to hypoglycemia were significantly lowered but growth hormone response was not modified by administration of 1 mg of dexamethasone. The administration of larger doses of dexamethasone (1 mg every 6 h for 2 days) almost completely suppressed basal levels of ACTH, cortisol and prolactin, as well as the hypoglycemia-induced release of these hormones. In contrast, the growth hormone response to hypoglycemia was only partially inhibited. These findings demonstrate that both basal secretion and hypoglycemia-induced release of prolactin, ACTH, cortisol and growth hormone are suppressible by glucocorticoids.

Adolescent↗
PubMed1975

The influence of exogenous estrogen on the circadian periodicity of circulating prolactin in women.

Ethinylestradiol (400 pg/day) does not only stimulate prolactin release in normal cycling women but also modifies the pattern of the circadian periodicity of circulating prolactin: the nocurnal rise is of reduced amplitude but covers a larger part of the nyctohemeral period as compared to the situation during a control period in the same subjects. The values start rising long before sleep, i.e., -t 2 pm, under estrogen treatment and during sleep, i.e., at 4 am, during the control period. In both cases, however, the values remain high until 8 am and are minimal at 12 am.

Adolescent↗
PubMed1975

Effect of methylergobasine maleate on serum gonadotrophin and prolactin in humans.

Intramuscular injection of 0.2 mg methylergobasine maleate3) (Methergin, Sandoz) in women on day 3 post-partum, in regularly menstruating women and in adult men, is followed within 30 to 75 min by a 50% decrease in serum prolactin concentration: the levels remain low until 180 min and increase between 180 and 240 min. The amplitude of the decrease is the same when prolactin is measured in terms of the same serum prolactin standard by a homologous ovine assay and by a homologous human assay. However, in the case of regularly menstruating women and of men serum prolactin concentration is some three times higher when estimated by the ovine assay than when estimated by the human assay. This difference between assay results obtained by the two radioimmunoassay methods could be due to heterogeneity of serum prolactin. However, non-specific effects of serum are not excluded. In regularly menstruating women and in men, intramuscular injection of 0.2 mg methylergobasine maleate is followed within 45 to 75 min by a 50% decrease in immunoreactive serum LH concentration without concomtant change in immunoreactive FSH. The depression of LH secretion lasts for 1 to 2 h. The circulating levels of HCG in post-partum women are not modified after intramuscular injection of Methergin. In humans as in animals and in in vitro studies, inhibition of prolactin and LH release induced by ergot drugs are likely due to both an indirect effect via the hypothalamus and to a direct effect on the pituitary cells.

Adult↗
PubMed1975

[Prevention of the malignant form of trophoblastic disease after a hydatidiform mole: systematic or selective chemotherapy].

After a mole has been evacuated there are two ways of treating the condition: routine chemotherapy from the beginning or chemotherapy reserved for selected cases. They offer the same chances of cure. Seeing that the risk of malignancy in our country is 5 per cent and that selective chemotherapy only exposes a small number of patients to the risk of such treatment, we have adopted the scheme of follow-up suggested by Bagshawe and recommended by OERTC. The follow-up is based on radio-immune assay for HCG carried out at regular intervals for two years. Only cases where the level of HCG is higher than 25,000 international units per litre, one month after curettage, or cases where the rise in HCG is associated with metastases, are treated with chemotherapy. In our experience, which is based on 20 cases, we acknowledge the value of radio-immune assaying. It is superior to immunological tests used for pregnancy diagnosis in sensitivity. It also appears to us that systematic treatment routinely administered and treatment based on raised levels of HCG two months after evacuation of a mole are useless. Only 3 cases were treated with chemotherapy out of the 20 cases that were followed up. We have had no malignancy after 2 and 3 years of checking back on the patients. Treatment given routinely from the start would have been unnecessary exposure to the risks of chemotherapy for 17 patients. Had we taken into account the abnormal rise in HCG after 8 weeks we would still have treated 7 patients instead of 3 with the same results as far as cure. We have worked out a graph for the drop in the levels of HCG after a mole has been evacuated. This may serve as a base for criteria for treatment in the future. Cases where the levels of HCG are above the 95 percentile are considered as at risk to evolve into malignant forms of disease. Consequently earlier treatment can be started (before the 6th month) without altering the number of patients who are going to be treated.

Choriocarcinoma↗
PubMed1975

[Prolactin and breast cancer].

In the animal, prolactin favours growth of breast tumours. Prolonged hyperprolactinemia occurring after the action of a carcinogenic agent increases the incidence of these tumours, but hyperprolactinemia, induced before the application of such an agent, reduces it. In women, there is also evidence in favour of the influence of prolactin on growth and on the incidence of breast carcinomas, but this evidence is still very indirect and sometimes contradictory. Serum levels of prolactin in women with carcinoma of the breast are identical to those observed in a female population of comparable age. In cases of generalised carcinoma, hysterectomy and ovariectomy induce remissions. These operations should be followed by a fall in prolactinemia. They also reduce the incidence of carcinoma of the breast in women. A full term pregnancy before the age of thirty years, apparently protects the mammary gland from the etiological agent. Now, in women, the secretion of prolactin is considerably increased during pregnancy.

Adult↗