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Biomedical subjects

A Dupont

Publications and source records attributed to A Dupont.

At least 217 records · Page 12Linked to original sources
PubMed1978

Enzymatic degradation of somatostatin by rat plasma and hypothalamus.

A highly sensitive and specific radioimmunoassay for somatostatin has been used to study inactivation of the neurohormone by plasma and hypothalamic peptidase(s). Specificity of the inactivation process was indicated by the absence of interference by addition of luteinizing hormone releasing hormone, thyrotropin-releasing hormone, oxytocin, or substance P. The inactivating ability of hypothalamic tissue and plasma was destroyed by heating and the protease inhibitor benzamidine prevented plasma activity, thus suggesting the enzymatic nature of the processes involved. The present data suggest that the inactivation of somatostatin by hypothalamus and plasma could be an important factor in the regulation of circulating somatostatin levels.

Animals↗
PubMed1977

Beta-endorphin: stimulation of growth hormone release in vivo.

Two micrograms of beta-endorphin (beta-lipotropin61-91) injected intraventricularly in rats that had been treated with antiserum against somatostatin led to a 6- and 10-fold stimulation of the concentration of plasma growth hormone (somatotropin) measured 10 and 20 min after injection of the peptide, whereas 400 mug of methionine-enkephalin led to a 4- to 6-fold increase of levels of plasma growth hormone at 10 min with a rapid return to basal levels at later time intervals. At doses of 5 and 25 mug, beta-endorphin led to a 20- to 30-fold stimulation of levels of plasma growth hormone, the maximal effect being measured between 20 and 30 min after injection. These data suggest the possible role of the endogenous opiate-like peptides in the control of growth hormone secretion.

Animals↗
PubMed1977

Traffic accidents involving psychiatric patients. Description of the material and general results.

The present investigation analyzes the characteristics of traffic accidents involving psychiatric patients and comprises all persons who during the period 1970-74 have been admitted to a psychiatric in-patient institution and who during the period 1972-74 have been involved in a traffic accident causing bodily injury. Accidents with psychiatric patients involved constitute about 5.7% of all traffic accidents reported in Denmark. Compared with the total group of accidents, they are characterized by an over-representation of women and of persons in the age group 25-54 years. Accidents with psychiatric patients are over-represented during the period July-September, and in areas densely built up. The accidents tend to be more complicated, and the psychiatric patients are more likely to get injured and be hopitalized due to the accident. The investigation is based exclusively on routinely collected data. The limitations with which the results are encumbered and the problems concerning methodology and comparison of different studies are discussed.

Accidents, Traffic↗
PubMed1977

Purification of plasma membrane fractions from the bovine pars intermedia and neurohypophyseal lobe and properties of associated adenylate cyclase.

A procedure for the isolation of plasma-membrane-enriched fractions from bovine 'pars intermedia' and neurohypophysis is described. Various fractions are isolated by differential centrifugation and discontinuous sucrose density gradients. The plasma-membrane-enriched fractions have a density in sucrose of 1.14 and 1.16 and the yields are 1.8 mg and 1.5 mg per gram of tissue for the pars intermedia and neural lobe, respectively. The fractions are characterized by electron microscopy and enzymatic assays. The plasma membrane fractions are mainly vesicular in nature and are free of nuclei, mitochondria, and microsomes when examined by electron microscopy. 5'-Nucleotidase (EC 3.1.3.5) and Mg2+-(Na+ + K+)-ATPase (EC 3.6.1.3) activities are concentrated in the plasma-membrane-enriched fraction. Also, adenylate cyclase (EC 4.61.1) shows a 5 to 10-fold purification in the isolated membrane fraction. NaF (10mM) gives a two to three-fold stimulation of enzymatic activity in all fractions studied The yields of adenylate cyclase, 5'-nucleotidase, and Mg2+-(Na+ +K+)-ATPase are about 6% in the membrane fraction.

Adenosine Triphosphatases↗
PubMed1977

Electron microscope immunohistochemical localization of substance P in the central nervous system of the rat.

Substance P is an undecapeptide that is distributed in many areas of the central nervous system. In order to clearly identify the structures and organelles containing substance P, an immunohistochemical localization of this peptide was performed at the ultrastructural level. Substance P was detected in dense core vesicles of many nerve endings in both the amygdaloid nucleus and the substantia gelatinosa of the spinal cord. These findings support the hypothesis that substance P could act as a neurotransmitter.

Amygdala↗
PubMed1977

Isolation of gamma-amino butyric acid from pig hypothalami and demonstration of its prolactin release-inhibiting (PIF) activity in vivo and in vitro.

A non-retarded fraction with prolactin-release inhibiting factor (PIF) activity obtained by chromatography of a concentrate of porcine hypothalami on carboxymethyl-cellulose was chromatographically distinct from catecholamines. This fraction was purified further by six steps involving chromatography on Sephadex G-25, countercurrent distribution, free-flow electrophoresis, and chromatography on triethylaminoethyl cellulose. The PIF-active substance was isolated and identified as gamma-amino-butyric acid (GABA) by: 1) amino acid analyses using sodium as well as lithium-based buffers for resolution of biological fluids, 2) thin-layer chromatography of underivatized material as well as phenylthiocarbamyl derivatives, and 3) mass spectroscopy. Natural and synthetic GABA inhibited prolactin, but not LH release in vitro from isolated rat pituitary halves at doses as low as 0.1 microgram/ml. The inhibition was proportional to the dose; natural and synthetic GABA possessed identical PIF activity. Synthetic GABA also decreased prolactin release in monolayer cultures of rat pituitary cells and inhibited TRH-stimulated prolactin release. The inhibition of prolactin release in vitro by GABA could not be blocked by perphenazine, which inhibits PIF activity of catecholamines. GABA also suppressed prolactin release in vivo, although large doses were needed. Either rapid iv injection or infusion of GABA in doses of 1 to 100 mg in rats significantly decreased serum prolactin levels, which were previously elevated by pretreatment with monoiodotyrosine perphenazine, chlorpromazine, haloperidol, or sulpiride. beta-hydroxy GABA significantly depressed prolactin release, but beta-(p-chlorophenyl)-GABA (Lioresal, CIBA) and 4 other analogs of GABA were not effective in vivo and/or in vitro. The results indicate that GABA can inhibit prolactin release by a direct action on the pituitary gland, but whether this effect is physiologically meaningful still remains to be determined.

Animals↗
PubMed1977

Stimulation of glucagon release by addition of anti-stomatostatin serum to islets of Langerhans in vitro.

Addition of anti-somatostatin serum to rat islets of Langerhans which had been previously maintained in organ culture for 48h, resulted in a marked stimulation of glucagon release with no change in the rate of insulin secretion during the entire 90 min period during which the secretion of both hormones was followed. Prior saturation of the anti-somatostatin serum with somatostatin prevented the stimulatory acting on glucagon release. These data strongly suggest a physiological role for endogenous somatostatin in the control of glucagon secretion.

Animals↗
PubMed1977

The development of the hypothalamo-pituitary axis in the neonatal rat: hypothalamic somatostatin and pituitary and serum growth hormone concentrations.

Using a specific radioimmunoassay technique for somatostatin (GHRIH), we have studied the ontogenesis of hypothalamic GHRIH in relation to pituitary and serum GH concentrations in immature rats. Hypothalamic GHRIH concentrations rose from minimal levels of 4.5 +/- 0.2 pg/microgram protein (mean +/- SEM) at 2 days to peak concentrations of 40.6 +/- 4.1 pg/microgram protein at 28 days followed by a progressive decline toward 50 days (7.0 +/- 0.8 pg/microgram protein). Pituitary GH concentration attained peak prepuberal values of 203.5 +/- 22.8 ng/microgram protein at 16 days with a further marked rise after puberty. Serum GH concentration was elevated to 2 days (53.3 +/- 5.7 ng/ml) and declined progressively to 5.9 +/- 1.5 ng/ml at 13 days. There was a highly significant inverse correlation between hypothalamic GHRIH and serum GH concentrations (r = 0.743, P less than 0.005). These data indicate that the hypothalamic regulatory mechanism for pituitary GH release develops during the neonatal period of the rat and suggest that GHRIH may play an important physiological role in this process.

Aging↗
PubMed1977

[Surgical problems of the primary sclerosing cholangitis (author's transl)].

The characteristics of the primary sclerosing cholangitis are a diffuse inflammation with fibrous thickening and narrowing of the biliar ducts. Two observations replying to strict characteristics are related. From attacks of angiocholitis, the disease generally progresses till a parmanent icterus and death occurs in a state of biliar cirrhosis. In the liver, the micro pathology consists in fibrous rings constricting the segmentary interlobular ducts. The diagnostic is mainly difficult and the prognostic is fatal in average time of 4 years of evolution althought we used corticoids that were administrated by local method as well as in the classical general way.

Adult↗