Search PubMed⌕ Search

Biomedical subjects

C Robyn

Publications and source records attributed to C Robyn.

At least 55 records · Page 3Linked to original sources
PubMed1982

The relationship between episodic variations of plasma prolactin and REM-non-REM cyclicity is an artifact.

The concept of concomitance between nadirs and peaks of plasma levels of PRL and, respectively, rapid eye movement (REM) and non-REM stages in sleep was reevaluated using 24 nighttime profiles of plasma PRL collected at 15-min intervals and the corresponding polygraphic recordings of sleep. The subjects were 5 healthy young male adults. Data were examined using the methodology described in the original report, consisting of averaging across individual nights PRL levels during REM and non-REM sleep stages as well as using a detailed spike by spike analysis of each individual pair of hormonal and sleep profiles. We showed that in our subjects, there was no relation, other than a purely random one, between episodic PRL fluctuations in plasma and REM-non-REM cycles.

Adult↗
PubMed1981

Serum levels of prolactin and milk production in women during a lactation period of thirty months.

Serum prolactin was measured in single blood samples collected from 219 nursing mothers of the Kivu region (Zaïre) during 30 post-partum months. In addition the number of feeding episodes per day and the amount of milk given to the child in 24 h were recorded. The mean serum prolactin levels remained around 1000 mu/l during the first 15 months of lactation and fell during the next 3 months to 550 mu/l. A decline in milk production per day occurred during the second year, but it was less marked than that of prolactin. This decline seemed to be associated with the decline in suckling frequency as the quantity of milk given per feed remained almost unchanged throughout lactation. The average amount of milk given by mothers with serum prolactin levels in the range of values seen in non-lactating and non-pregnant women (about 500 mu/l) is nevertheless of some 35 g per feeding or 260 g per day. These results demonstrate that milk production can be maintained in women with normal levels of prolactin and suggest that prolactin plays a permissive role in established lactation.

Female↗
PubMed1981

Prolactin secretion in Cushing's disease.

PRL secretion was evaluated in 11 patients with Cushing's disease (7 women, 4 men). Basal morning levels were elevated when compared to normal subjects. PRL reactivity to TRH and hypoglycemia was normal in most patients. The 24-h mean PRL levels were elevated, with partial or total alteration of the nyctohemeral rhythm. Cure of Cushing's disease by selective pituitary adenomectomy restored a normal PRL secretion.

Adenoma↗
PubMed1981

Serum prolactin concentrations in mangabey (Cercocebus atys lunulatus) and patas (Erythrocebus patas) monkeys in response to stress, ketamine, TRH, sulpiride and levodopa.

An homologous radioimmunoassay for human serum prolactin was validated to measure serum prolactin in 10 mangabey and 7 patas monkeys. Mean basal levels of serum prolactin were almost identical in the males of both species and in immature and mature males. However, basal levels were higher in females than in males. Serum prolactin was enhanced by stress, i.v. injection of TRH and intramuscular injection of a potent dopamine antagonist (sulpiride). The rise in serum prolactin observed after i.m. injection of ketamine hydrochloride used as anaesthetic was of small amplitude and short duration. Oral administration of levodopa was followed by a significant fall in serum prolactin. Sexual maturity did not influence the responses to TRH or sulpiride. The mangabeys were more sensitive to sulpiride but less sensitive to levodopa than were the patas monkeys. The variations in serum prolactin levels observed in these monkeys under the influence of stress, TRH, sulpiride and levodopa are similar to those observed in man to the same stimuli, although the experimental conditions were quite different.

Animals↗
PubMed1981

Changes in concentrations of serum prolactin, FSH, oestradiol and progesterone and of the sex skin during the menstrual cycle in the mangabey monkey (Cercocebus atys lunulatus).

Daily blood samples were collected from 6 regularly menstruating mangabey monkeys. Because serum LH could not be measured by a radioimmunoassay for human LH, Day 0 was taken as the day of maximum serum oestradiol concentration. The hormone patterns were very similar to those of other cercopithecids and women. However, the peak of serum progesterone was lower in mangabeys than in women. There was no distinct peak of serum oestradiol during the luteal phase of mangabeys but the average levels were higher than during the early follicular phase, a pattern more similar to that in other non-human primates than in women. Serum prolactin rose by about 50%, 48 h after the serum oestradiol peak, then declined during the mid-luteal phase before rising at the end of the cycle. Changes in the sex skin dimensions followed the same pattern as the serum oestradiol concentrations.

Animals↗
PubMed1981

A simple and rapid solid-phase radioimmunoassay for serum progesterone, using the protein A of Staphylococcus aureus as immunoadsorbent.

A simple, rapid, and inexpensive radioimmunoassay method for serum progesterone is described, which uses a solid-phase technique for separation of antibody-bound from antibody-free progesterone. Rabbit antiprogesterone immunoglobulins are adsorbed on the protein A of formaldehyde- and heat-treated Staphylococcus aureus cells (Pansorbin; Calbiochem-Behring Corp., La Jolla, Calif.). The suspension of antibody-coated pansorbin retains all its binding activity (23% for 500 microliter of a 0.033% suspension) of 1-2-H(N)-progesterone (20,000 cpm in 100 microliter) when kept at +4 degrees or at -25 degrees C for at least 4 months. Dose-response curves obtained with ether-serum extracts and with the progesterone standard do not deviate significantly from parallelism. The progesterone standard gives identical dose-response curves whether diluted in the assay buffer or in a progesterone-free ether-serum extract. The sensitivity of the assay is 0.02 ng/assay tube. The intra-assay variation coefficient is 16%, and the routine interassay variation coefficient is 17%. The mean serum progesterone concentrations were 0.55 ng/ml during the follicular phase of the menstrual cycle and 12.5 ng/ml during the luteal phase. The average blank value for distilled water was 0.02 ng/assay tube.

Adolescent↗
PubMed1980

Hyperprolactinaemia during prolonged lactation: evidence for anovulatory cycles and inadequate corpus luteum.

Serum progesterone and prolactin were measured in single blood samples collected from 176 mothers during a lactation period of 2 years and from fifty-six non-lactating, non-pregnant and regularly menstruating women from the Kivu region (Zaïre). On the basis of serum progesterone levels, evidence of corpus luteum activity was obtained in 61% of non-lactating women; but only 20% of non-amenorrhoeic lactating mothers. This suggests an increased incidence of anovulatory cycles and/or cycles with short luteal phases among nursing mothers. The incidence of corpus luteum activity was 8% in amenorrhoeic lactating mothers. In this 8% recurrence of ovulation preceded return of menstruation. Mean serum progesterone was significantly higher and serum prolactin significantly lower in the non-lactating women than in the nursing mothers. This suggests that although ovulation occurs, corpus luteum activity is inadequate in hyperprolactinaemic nursing mothers.

Anovulation↗
PubMed1980

Immunoenzymatic localization of prolactin-like immunoreactivity in decidual cells of the endometrium from pregnant and nonpregnant women.

Prolactin-like immunoreactivity has been localized by an immunoenzymatic method in the decidual cells of the endometrium in cases of early (10 weeks) normal pregnancy, (12 weeks) molar pregnancy, (8--10 weeks) tubal pregnancy, and of a nonpregnant woman under progestogen (lynestrenol) treatment. A specific endocrine influence, predominantly progestogenic, rather than the implantation of trophoblastic tissue seems to be required for the appearance of prolactin-like immunoreactivity in the decidual cells of the endometrium.

Endometrium↗
PubMed1980

Prolactin and fructose in human seminal fluid.

Two hundred thirty-six semen specimens were obtained in the sterility clinic by masturbation after 3 days of abstinence. In a radioimmunoassay for prolactin (NIH, batch no. 5) the dose-response curve obtained with seminal fluid prolactin was parallel to that obtained with serum prolactin. The average seminal fluid prolactin was 780 microunits/ml (35 ng/ml), three times higher than serum prolactin concentration in men. No relationship was found between seminal prolactin concentration and sperm count (per ml or per ejaculate) or sperm motility. There was a significant and positive correlation between seminal prolactin concentration and fructose concentration. The relationship was of an exponential type. Seminal fructose increased progressively with seminal prolactin; however, for prolactin values above 850 microunits/ml, there was no further increase in seminal fructose. A similar relationship was observed between seminal prolactin concentration and volume of the semen specimens. These data support the concept that prolactin may play a key role in male fertility, perhaps by influencing the composition of the milieu where spermatozoa survive rather than by direct effect on spermatogenesis.

Fructose↗