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Biomedical subjects

G Pelletier

Publications and source records attributed to G Pelletier.

At least 559 records · Page 31Linked to original sources
PubMed1983

Immunological characterization of endorphins, adrenocorticotropin, and melanotropins in frog hypothalamus.

To gain more information about the nature and regulation of opiomelanocorticotropic peptides in the frog diencephalon, radioimmunological determinations of alpha- and beta-MSH. ACTH, beta- and gamma-endorphins have been performed in hypothalamic extracts. Sephadex G-50 gel filtration revealed a single peak of alpha-MSH-like immunoreactivity (alpha-MSH-LI) comigrating with synthetic alpha-MSH. Two peaks of ACTH-LI were observed; the major one eluting slightly before human ACTH. Using a porcine beta-endorphin antiserum which exhibited 45% cross-reaction (on a molar basis) with ovine beta-LPH, one major peak of beta-endorphin-LI and two additional components were observed in the elution profile; none of these peaks coeluted with synthetic porcine beta-endorphin. No significant beta-MSH or gamma-endorphin-LI was detected. To investigate a possible role of glucocorticoids on the level of opiomelanocorticotropic peptides in frog hypothalamus, 60 male frogs were treated with dexamethasone (300 micrograms/day) during 8 days. Dexamethasone treatment did not modify the chromatographic distribution and the total amount of alpha-MSH-LI and ACTH-LI in hypothalamic extracts. A slight (15%) increase in beta-endorphin-LI was even observed after 8 days of dexamethasone treatment. From these results it is concluded that three classes of opiomelanocorticotropic peptides are present in the frog hypothalamus in the following order of concentration: beta-endorphin-LI greater than alpha-MSH greater than ACTH. In addition, circulating glucocorticoids which significantly reduce the concentration of opiomelanocorticotropic hormones in the distal lobe of the frog pituitary (S. Jégou, M. C. Tonon, F. Leboulenger, C. Delarue, J. Côté, G. Pelletier, and H. Vaudry (1981a). In "Adv. Physiol. Sci.' E. Stark, G. B. Makara, Zs. Acs, and E. Endröczi, eds., Vol. 13, pp. 129-133. Pergamon, Budapest.) do not modify the amount of these peptides in the hypothalamus.

Adrenocorticotropic Hormone↗
PubMed1983

alpha 2u-Globulin is present in the rat anterior pituitary.

The possibility that the pituitary gland may contain as yet undiscovered regulatory factors is intriguing. Recent reports have suggested the presence, in the anterior pituitary, or a number of proteins of extrapituitary origin. alpha 2u-Globulin, a rat serum and urinary protein, previously shown to be synthesized in the submaxillary gland and in the liver under anterior pituitary control, has now been localized by immunocytochemistry in the cytoplasm of some cells of the anterior pituitary. No alpha 2u-globulin could be detected in either the intermediate or posterior pituitary. The presence of alpha 2u-globulin was confirmed and quantitated by radioimmunoassay. Using RNA blot analysis and cloned alpha 2u-globulin cDNA probes, we could not detect alpha 2u-globulin mRNA sequences in pituitary RNA, indicating that alpha 2u-globulin is not synthesized therein. The presence of alpha 2u-globulin, presumably of circulatory origin, in certain anterior pituitary cells suggests that it may play a role in anterior pituitary function.

Aging↗
PubMed1983

Identification of ending containing dopamine and vasopressin in the rat posterior pituitary by a combination of radioautography and immunocytochemistry at the ultrastructural level.

In order to study the morphological relationship between the dopaminergic and the vasopressinergic endings in the rat posterior pituitary, a combination of radioautography and immunocytochemistry techniques was applied to the same ultrathin section of the posterior pituitary. Immunocytochemical localization (peroxidase-antiperoxidase technique) of vasopressin was first applied, followed by the radioautography detection of [3H] dopamine that had been injected 30 and 60 min before fixation. This double labeling technique has established that the dopaminergic endings that contain both dense core vesicles (60-100 nm in diameter) and small clear vesicles are always found in close proximity to vasopressinergic neurosecretory endings, suggesting an interaction between these two systems. This relatively easy approach should be very useful to study the connections between different neurotransmitter systems in the nervous system.

Animals↗
PubMed1983

Catecholaminergic control of alpha-melanocyte-stimulating hormone (alpha MSH) release by frog neurointermediate lobe in vitro: evidence for direct stimulation of alpha MSH release by thyrotropin-releasing hormone.

The role of dopaminergic and adrenergic innervation of the intermediate lobe of amphibian pituitary in the release of alpha MSH has been studied in vitro. Neurointermediate lobes of frog (Rana ridibunda Pallas) have been perifused in amphibian culture medium (ACM) for 5-7 h. alpha MSH released in the effluent perifusate was measured by means of a sensitive and specific RIA. No significant morphological alteration of neurointermediate lobe cells was observed during the perifusion experiment, even at the electron microscopic level. The existence of dopaminergic receptors, responsible for an inhibition of frog melanotrophs, was shown using the dopaminergic agonists apomorphine (10(-6) M) and bromo-2-ergocryptine (10(-8) and 10(-7) M), which initiated a marked reduction of alpha MSH secretion. The effect of apomorphine was obliterated by the dopaminergic antagonist haloperidol. Haloperidol itself induced a dose-related stimulation, and the monoamine oxidase inhibitor nialamide (4 x 10(-3) M) inhibited alpha MSH secretion. In addition, haloperidol led to a complete reversal of the inhibitory effect of nialamide on alpha MSH secretion. These results demonstrate the existence, in the parenchyme of the intermediate lobe, of dopaminergic nerve fibers that are functionally active. The beta-adrenergic agonist isoproterenol was responsible for a dose-related stimulation of alpha MSH secretion; the stimulatory effect was reversed by the beta-adrenergic antagonist propranolol. TRH is a potent stimulator of alpha MSH secretion in amphibians. Since haloperidol and propranolol did not abolish the stimulation of alpha MSH release induced by TRH, it appeared that TRH action was not mediated via an inhibition of dopamine release or via a stimulation of adrenergic nerve fibers.

Animals↗
PubMed1983

Effect of age and glucocorticoid administration on the proteolytic activity of gastric mucosa: a comparative study in the young rat, calf and piglet.

The proteolytic activity of gastric mucosa markedly increased from 2 to 4 wk of age in rats and from birth to 8 wk in pigs. In calves it was at adult level at birth, then decreased until d 14 and remained at a relatively low level up to d 56 of age. Early postnatal glucocorticoid injections increased (P less than .05) the proteolytic activity of gastric mucosa in rats, decreased (P less than .05) the abomasal proteolytic activity in calves and had no significant effect in pigs. The high levels of proteolytic activity observed in the rat at earlier ages after glucocorticoid treatment suggested a precocious maturation of the gastric mucosa. Injections of different doses of hydrocortisone acetate and dexamethasone to calves and rats indicated that proteolytic activity of gastric mucosa is only sensitive to high doses (i.e., nonphysiological) of glucocorticoids. The response of gastric mucosa to glucocorticoid injections depended on the animal's age; maximum response was obtained in the early postnatal period while minimal response was observed after weaning.

Abomasum↗
PubMed1983

Effects of administration of glucocorticoids on pancreas and growth of dairy calves.

The possibility of reducing calf weaning age by accelerating development of the pancreas of dairy calves with hormone administration was studied. Hydrocortisone acetate or dexamethasone was injected at 3 or 17 days of age to determine their effects on the pancreas. Hydrocortisone acetate injections (50 mg/kg body weight) to 3-day-old calves increased within 4 days the pancreas weight, amylase and chymotrypsin activities, and proteins, ribonucleic acid, and deoxyribonucleic acid contents. However, the glucocorticoid injection had no effect on activities of digestive enzymes of the 21-day-old calves. The pancreas hypertrophied in the 7-day-old calves following hormonal treatment. In the 21-day-old calves administration of glucocorticoids brought about hyperplasia of the pancreas but no hypertrophy of the tissue. This response of the pancreas to injections of glucocorticoids in the 7-day-old calves was interpreted as an acceleration of normal development of the tissue. Hydrocortisone acetate injection to 3-day-old calves had no effect on feed consumption but had a small depressive effect on growth of calves at 14 and 21 days of age.

Age Factors↗
PubMed1983

[Acute alcoholic hepatitis and death of cirrhotic patients].

Alcoholic hepatitis (AH) seems to be less frequent and to play a lesser role in the death of cirrhotic patients than previously acknowledged. The purpose of this work was: 1) to study the cause of death of cirrhotic patients 2) to determine the prevalence of AH among these patients and 3) to describe the clinical and laboratory features of cirrhotic patients with AH. The data were collected from a series of 107 necropsies in cirrhotic patients without hepatocellular carcinoma. The statistical analyses were carried out with an IRIS 80 computer. Severe liver failure with jaundice and encephalopathy, hemorrhage and uncontrolled infection with septic shock represented 84 p. 100 of the causes of death in patients with cirrhosis. Seventy-nine out of 107 patients (74 p. 100) had no AH (group 1), and 28 (26 p. 100) had AH (group 2): AH was mild in 15 cases and severe in 13 cases. All patients with AH died from a complication directly related to their liver disease while 21.5 p. 100 of patients without AH died from a complication not related to cirrhosis. The clinical and laboratory features of the patients without AH and cirrhosis differed from those of patients without AH by: a more frequent presence of fever (p less than 0.01), the absence of important weight loss (p less than 0.001), the total absence of abstinence (p less than 0.05), a higher value of ASAT/ALAT ratio, of serum levels of total bilirubin (p less than 0.01) and conjugated bilirubin (p less than 0.05), gamma glutamyl transpeptidase (p less than 0.001) and total cholesterol (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1983

[Rhythmic echographic palpation. Echosismography. A new technic of differentiating benign and malignant tumors by ultrasonic study of tissue elasticity].

The echographic rhythmic palpation (echosismography) is a new method which completes classical sonography. It studies the elastic behaviour of the tissues after their mechanical excitation which are analysed in the T.M. mode. When displayed in classical sonographic technique the lesion is located with calipers. Calipers allow the recognizing of the tumor level at any moment in time motion mode. Vibrations are then applied on the skin as near as possible to the lesion. A regular frequency of 1,5 impulsion per second at a constant pressure of 500 gr on 4 cm2 is used. The response of resonating tissues to vibratory excitation is recorded and characterized by the amplitude of the oscillations (sinusoïdal shape). Benign tumors always gave sinusoïdal type oscillations. Most of this kind of tumors were semi-liquid or solid. Malignant tumors gave typical flat curves in 84% cases. Some malignant tumors (16%) gave benign type sinusoïdal oscillations. They had a small size, less then 2 cm diameter. Some of them where to superficial so they had easily induced oscillations over the excitation level. Echosismography enables to improve the diagnosis when compared with classical sonography in about 20% of cases.

Diagnosis, Differential↗