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Biomedical subjects

J Bertrand

Publications and source records attributed to J Bertrand.

At least 109 records · Page 6Linked to original sources
PubMed1985

Comparative study of histological and kinetic variations of the digestive mucosa and pancreatic parenchyma after hypophysectomy in the rat. Light and electron microscopic study.

Variations of the pancreatic parenchyma, the gastric mucosa and the intestinal mucosa were studied in adult male Wistar rats on day 8 and 15 after hypophysectomy. All results were compared with those obtained in pair-fed control rats. Hypophysectomy affected small intestine as well as gastric mucosa. Hypotrophy was observed on day 8 as most of the morphological parameters reached the maximal decrease. By contrast, hypoplasy occurred on day 15, when the labeling index (LI) decreased significantly. In the intestine, however, a decrease of the LI was observed only for the upper proliferative cells of the crypts. In the gastric mucosa, the LI was reduced only in the proliferative zone containing progenitor cells (isthmic region). Consequently, the cell differentiation is not similarly affected on all levels of the digestive tract.

Animals↗
PubMed1985

Increased dopaminergic inhibition of prolactin in the hypoprolactinaemic IPL nude rat.

In this study, aimed at investigating whether dopaminergic regulation of prolactin could be implicated in the hypoprolactinaemia observed in the IPL nude rat, dopaminergic inhibition of prolactin was suppressed using a catecholamine synthesis inhibitor alpha-methyltyrosine (MT) and a dopaminergic antagonist sulpiride. Adult male rats (IPL nude and normal) were injected through implanted atrial cannulae with either MT (250 mg/kg) or physiological saline (control). Rats were decapitated 2 h after the injection. Plasma prolactin levels, compared with basal values, increased by 15.6 +/- 1.9 (S.E.M.)- and 5.89 +/- 0.6-fold in IPL nude and normal rats respectively. This difference was highly significant. The pituitary prolactin content was decreased in both groups. In a second experiment, adult male IPL nude or normal rats were injected with either sulpiride (1 mg/kg) or saline and decapitated 2, 4, 8, 12, 14 and 24 h later. Plasma prolactin levels, compared with basal values, were increased in rats injected with sulpiride by 9.2 +/- 1.8 and 3.4 +/- 0.7-fold in IPL nude and normal rats respectively. The pituitary prolactin content was reduced more in IPL nude than in normal sulpiride-injected rats. These data suggest that prolactin secretion, as well as synthesis, is under an increased dopaminergic inhibition in the male IPL nude rat.

Animals↗
PubMed1985

[Human monoclonal antibodies against surface antigens of Langerhans cells from lymphocytes of diabetics transformed by Epstein-Barr virus].

Human monoclonal antibody against islet cell surface antigens was generated from a pre-diabetic patient's peripheral blood lymphocytes transformed with Epstein-Barr virus. Reactivity of these transformed lymphocytes was evaluated using indirect immunofluorescence on rat islet cell suspensions and frozen sections of human pancreas. Several lymphoblastoid cell lines that react with islet cell surface were obtained. Preliminary immunoblots with enriched rat islet cell membrane antigens suggest a reactivity toward a 64 kdalton antigen.

Animals↗
PubMed1985

[Kinetics of the testicular steroidogenic response to stimulation by placental gonadotropin hormone. VI. Enzyme deficiencies of testicular biosynthesis].

The kinetics of the responses of plasma testosterone (T) its precursors and estrogens to a single injection of human chorionic gonadotropin (hCG) was studied in 9 46 XY subjects affected with one of 4 inborn errors of testicular biosynthesis. In the adults (n = 4), the kinetics and profile of the hormonal responses to hCG were qualitatively comparable to those previously described in normal adult men, and the profile of response characteristic of the hCG-induced steroidogenic desensitization was observed, suggesting that the 17,20 desmolase blockade induced by hCG is superimposed to the inborn enzymatic defect. In the prepubertal patients (n = 5), testicular desensitization was not observed, as in prepubertal controls. However, T precursors, each marker of a given enzymatic blockade, significantly rose several fold 2-5 days after the hCG injection, while they do not in normal children. The results also show that an hCG test is necessary for a clear-cut diagnosis of a given enzymatic block in children, but is not in adults. The single hCG injection protocol used in this study offers a sophisticated way of a qualitative analysis of the testicular secretory products, but is not a must.

17-Hydroxysteroid Dehydrogenases↗
PubMed1985

[Somatocrinin and children in 1984. Application to the etiological diagnosis of somatotropin deficiencies].

A single acute IV injection (1 microgram/kg) of the synthetic replicate of Somatocrinin (GRF) in 40 children with growth hormone (GH) deficiency induces a marked plasma GH increase, although heterogeneous. Clinical tolerance is excellent. Compared to Propranolol + Glucagon (P + G), GRF induces a better GH response. It also discriminates better idiopathic GH deficiency (n = 13), where mean GH peak = 6.5 ng/ml (3.3 after P + G) from GH deficiency secondary to a brain tumor (n = 24) where mean GH peak = 15.5 ng/ml (5.0 after P + G) GRF induces a slight Prolactin (Prl) increase, more obvious when basal Prl is elevated. However there is no correlation between GH and Prl responses to GRF even with basal hyperprolactinemia. GH response to GRF seems to slowly decrease after radiation therapy. GRF is a new potent, well tolerated secretagogue of GH and improves the diagnostic quality of the etiology of GH deficiency.

Adolescent↗
PubMed1984

Prolactin receptors in the rat mammary gland. Change during the estrous cycle.

Ovine prolactin (o-PRL) binding to mammary gland membranes was studied during the estrous cycle in the rat. Groups of rats were decapitated throughout the 4-day estrous cycle at 10 h00 on the days of diestrus I, diestrus II and estrus and at 10 h00, 12 h00, 16 h00 during the day of proestrus. Daily vaginal smears were taken to determine the stage of the estrous cycle which was also controlled by PRL and LH serum levels. Prolactin receptors were quantified in the 100 000 g pellet. For one Scatchard analysis, mammary gland membranes from 5 animals were pooled. Results given are the mean of 4 or 5 pools. Results obtained showed that the apparent affinity constant (KA) remained unchanged during the days of diestrus II and at all the times studied of proestrus and showed a slight but significant decrease on the days of estrus and diestrus I (or metestrus). The binding capacity did not vary from the day of diestrus II to the proestrus 16h00 (11.3 +/- 2.8 fmoles/mg protein) but sharply increased on the day of estrus (190.4 +/- 35.9 fmoles/mg protein). Binding capacity remained elevated on the day of diestrus I. This increase of PRL receptors on the day of estrous would appear to be an important step in preparing mammary gland for pregnancy and lactation.

Animals↗
PubMed1984

Prolactin receptors in the hypoprolactinemic male rat (IPL nude rat): measurement in testis and induction in liver.

In order to evaluate the importance of PRL in the regulation of its own receptors, characteristics of specific binding for PRL were studied in membrane preparations from liver and testis of a new hypoprolactinemic male rat, the IPL nude male rat, and this was compared to those found for normal male rats. Under basal conditions, hepatic specific binding of PRL in IPL nude rats, as in normal rats was not detectable. Following castration, it became detectable in both groups, and was 6.99 +/- 0.78% and 6.34 +/- 0.87% for IPL nude and normal rats respectively. Under such conditions, the apparent affinity constant (Ka) and the binding capacity (Nmax) obtained were also similar for both groups (Ka) = 1.36 +/- 0.14.10(9) M-1, Nmax = 102 +/- 14 fmol/mg protein in IPL and Ka = 1.34 +/- 0.28.10(9) M-1, Nmax = 97 +/- 11 fmol/mg protein in normal rats) although a decrease in serum levels of PRL was observed in both groups. This decrease was greater for IPL nude rats. As already reported, estradiol injection following castration was able to further increase the percentage of PRL hepatic specific binding (4 times). Furthermore, our results demonstrated that the affinity constant was significantly increased by estradiol injection in both groups. On the other hand, for testicular PRL binding characteristics, a statistically significant difference was found between IPL nude and normal rats. The PRL specific binding percentage was 7.01 +/- 0.85% for the IPL nude rat and 10.07 +/- 0.64% for the normal rat. By Scatchard analysis, the Ka of testicular membranes for labelled oPRL was similar in both groups, while the capacity differed (Nmax = 9.82 +/- 1.25 fmol/mg protein for IPL nude rat and Nmax = 26.06 +/- 4.39 fmol/mg protein for normal rats). These data established the fact that IPL nude male rats presented characteristics of hepatic PRL receptors similar to those of normal rats, while their testicular oPRL binding significantly differed. These findings therefore suggest that in genetic hypoprolactinemic rats (IPL nude rats), PRL might be more involved in the regulation of testicular PRL receptors than in that of hepatic receptors.

Animals↗
PubMed1984

Demonstration of an antiglucocorticoid action of progesterone on the corticosterone inhibition of beta-endorphin release by rat anterior pituitary in primary culture.

The effects of progesterone or 17 alpha-hydroxyprogesterone on corticosterone regulation of beta-endorphin (beta-end) release have been studied in vitro using primary culture of rat anterior pituitaries. Incubation of pituitary cells with ovine corticotropin-releasing factor (CRF) for 2 h resulted in a dose-dependent increase in beta-end release. Maximal stimulation was obtained with 200 ng/ml CRF. Preincubation for 2 h with corticosterone resulted in a dose-dependent inhibition of CRF-induced beta-end release. When the cultures were preincubated for 2 h with 200 ng/ml corticosterone and increasing concentrations (1, 10, 100, 1,000, and 10,000 ng/ml) of progesterone, a significant decrease in the corticosterone feedback action was observed with 100 ng/ml progesterone. Complete inhibition of the action of 200 ng/ml corticosterone was achieved with 10,000 ng/ml progesterone. Moreover, when the cultures were preincubated with increasing concentrations of corticosterone in the presence of 100 ng/ml progesterone, the ED50 of corticosterone increased significantly from 212 +/- 36 to 940 +/- 42 ng/ml (mean +/- SEM; P less than 0.01). Under the same conditions, 17 alpha-hydroxyprogesterone had no effect. These data demonstrate that progesterone antagonizes the corticosterone feedback inhibition of beta-end release by rat anterior pituitary.

Animals↗
PubMed1984

[Spontaneous rupture of an aneurysm of the splenic artery in pregnancy. Apropos of a new case].

The authors report a case of a two para who was admitted as an emergency after collapsing at the end of her pregnancy. Various clinical examinations carried out on admission showed that she was in a state of hypovolemic shock with a marked drop in her blood pressure and a fast pulse as well as pain in the left hypochondrium radiating up to her shoulder. From the obstetrical point of view, there had been no bleeding and no uterine contractions and the fetal heart tracing showed a rate of 135. After intensive efforts at resuscitation an urgent laparotomy was carried out with as a first step Caesarian section which confirmed that there was no pathology in the placenta or uterus, followed by exploration of the abdominal cavity which revealed a large retro-peritoneal haematoma together with a ruptured aneurysm in the hilum of the spleen. Splenectomy was carried out after haemostasis of the splenic pedicle had been performed and this allowed her to recover without complications. Following this case the authors looked up the world literature and confirmed that the pathology was classic but very rare indeed, there being only 66 published cases. As far as its aetiology was concerned this aneurysm is not the same as a classical splenic aneurysm. The development of the aneurysm seems to take place during the pregnancy and the reason for this arterial aneurysm and its rupture in unknown. A theory has been advanced that circulatory and haemodynamic factors acquired in pregnancy reveal the congenital factor that is already present.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

[Kinetics of the testicular steroidogenic response to stimulation with placental gonadotropin in the prepuberal boy].

The kinetics of the plasma level responses of steroid hormones to a single injection of human chorionic gonadotrophin (hCG) (100 Ul/kg) was studied for one week in 7 prepubertal boys. Plasma testosterone levels progressively increased up to 8.22 +/- 1.33 nmol/l, usually at the 100th hour. The kinetics of dihydrotestosterone was quite similar. On the other and, progesterone, 17 alpha-hydroxyprogesterone and delta 4-androstenedione did not change significantly; 17 beta-estradiol slightly increased 5 to 7 days later. This profile of response is deeply different from those observed in adults, in whom are observed an early response (24 hrs) of 17 alpha-hydroxyprogesterone and estradiol and a two-phase response of testosterone. These results show that the hCG-induced steroidogenic desensitization is present only in patients previously exposed to a certain level of gonadotrophic stimulation (endogenous or exogenous).

Adolescent↗
PubMed1983

Unresponsiveness of prolactin to repeated injection of sulpiride in man.

The prolactin (PRL) response to repeated injections of sulpiride, a dopamine antagonist, was evaluated in 18 healthy young men. Each subject received one or two injections of sulpiride 1 mg/kg i.m. The first injection was always given at 9 a.m. and the second after 2, 8, 24 or 48 h. Blood samples were taken through an indwelling venous catheter every 20 min during the first hour following the injection and then hourly for 12 h. The first sulpiride injection increased serum PRL level 10-fold the peak being reached after 20 or 40 min. The second injection up to 24 h had no effect on serum PRL, but when two sulpiride injections were given at a 48 h-interval, both caused a sharp increase in PRL. To conclude, PRL cells in man, after a sulpiride injection, may therefore be unresponsive to a second sulpiride injection for more than 24 h.

Adult↗
PubMed1983

A new hypoprolactinemic rat strain. Prolactin, luteinizing hormone, follicle-stimulating hormone, testosterone and corticosterone levels in males and effects of two anesthetics.

A new strain of rat, the IPL nude rat, derived by spontaneous mutation from the Sprague-Dawley strain, is characterized by a lack of hair, delayed puberty and a total lack of lactation. To characterize partially the endocrine system in this rat, serum levels of prolactin (Prl), luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone and corticosterone were quantified. The content of gonadotropins and Prl in the pituitary gland was also measured. Blood samples were collected following decapitation or by cardiac puncture after ether or ketamine anesthesia. Serum levels of Prl were decreased by approximately 50% in IPL nude compared to normal Sprague-Dawley rats, regardless of the method used for collection of the samples. There were also significantly reduced levels of testosterone, LH and FSH in the serum collected from IPL nude rats. Levels of corticosterone in serum were similar in IPL nude and normal rats. There was the same relative response to anesthesia in the levels of all the hormones measured when the data from IPL nude and normal rats were compared. The quantities of LH, FSH and Prl contained in the pituitary of the IPL nude rats were not significantly different from those observed in normal rats. These data suggest that the serum hormone deficiencies observed in the nude IPL rat may be due to an altered regulation of hormone production by hypothalamic factors.

Anesthetics↗
PubMed1983

Postreceptorial refractoriness of prolactin release mechanisms.

While a first injection of the antidopaminergic benzamide drug, sulpiride, induced a large rise in plasma prolactin (PRL) levels in chronically cannulated adult male rats, a second injection given 2 h later was totally inactive although the pituitary content of the hormone was still 76% of the initial value. When the second injection was given 8 h after the first it was slightly effective, but when administered 24 h later it was as effective as the first. The second of two consecutive injections of haloperidol given at 2-h intervals, or an injection of morphine given 2 h after sulpiride, were incapable of inducing a release of PRL. Two hours after an injection of sulpiride, a 30-min period of immobilization stress induced a significant rise in plasma PRL levels. A significant rise in plasma PRL levels was also observed when larger doses of sulpiride were given 2 h after a first injection of the drug. Apomorphine was at least as effective an inhibitor of PRL secretion when given 2 h after sulpiride than when injected after saline. In vitro studies of dopaminergic binding sites revealed the presence, in pituitary glands of sulpiride-treated rats, of receptors not modified by the drug. These data suggest that the only plausible explanation for the ineffectiveness of the second of two consecutive injections of sulpiride is the development of a state of refractoriness of the mechanisms that subserve the release of PRL induced by suppression of the inhibitory dopaminergic tonus.

Animals↗
PubMed1983

Testicular responsiveness to hCG of the ovine fetus in the last third of gestation.

The in vivo and in vitro testicular responsiveness to hCG of hemicastrated lamb fetuses 95-99, 110-118 and 130-141 days of gestational age was studied. Basal plasma testosterone (T) levels were similar at all ages (less than 0.25 ng/ml), while the mean testicular concentrations of dehydroepiandrosterone sulfate (DHA-S), 17 alpha-hydroxyprogesterone (17-OHP) and T were higher in 95- to 99-day-fold fetuses. Plasma T levels and the concentration of T, DHA-S, 17-OHP, androstenedione (A) and cyclic adenosine 3'5'-monophosphate (cAMP) were increased by hCG in the hemicastrated animal at all ages. cAMP and T production by enriched preparations of dispersed interstitial cells from control testes was increased by hCG in all groups. In fetuses pretreated with hCG in vivo the addition of hCG in vitro failed to modify cAMP and T production. 100 micrograms of LHRH to a 130-day-old fetus increased plasma LH and T levels. From these experiments, it is suggested that the low plasma LH and T levels found throughout the last trimester of fetal life reflect a relative lack of endogenous LHRH synthesis and/or release, rather than reduced testicular steroidogenic capacity.

17-alpha-Hydroxyprogesterone↗