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G Pelletier

Publications and source records attributed to G Pelletier.

At least 541 records · Page 30Linked to original sources
PubMed1984

Immunocytochemical localization of neuropeptide Y (NPY) in the human hypothalamus.

In order to study the distribution of neuropeptide Y-like immunoreactivity in the human hypothalamus, an immunocytochemical localization of this peptide was performed. Using antibodies developed against synthetic porcine neuropeptide Y (NPY), we have been able to localize immunoreactivity in neuronal cell bodies located exclusively in the infundibular nucleus. Immunostained fibers were found in several regions in the hypothalamus with a high concentration in the periventricular areas. Fibers were also found in the neurovascular zone of the median eminence, the pituitary stalk and the posterior pituitary. These results suggest that immunoreactive material related to porcine NPY is present in the human hypothalamus, with a distribution similar to that observed in the rat.

Aged↗
PubMed1984

Electron microscope immunocytochemical localization of neuropeptide Y (NPY) in the rat brain.

In order to identify the neuronal structures as well as the intracellular organelles which contain the newly discovered brain peptide, neuropeptide Y (NPY), we have localized this peptide by immunoelectron microscopy in brain areas containing high levels of NPY. Ultrastructural studies using both the pre- and post-embedding immunoperoxidase techniques have shown that NPY-like immunoreactivity could be observed in neuronal cell bodies, dendrites and axonal processes. In terminals, the reaction product was associated with the large dense core vesicles. Only a small percentage of the positive terminals were seen making synaptic contacts. These results support the hypothesis that NPY can act as a neurotransmitter or neuromodulator.

Animals↗
PubMed1984

Blood transfusions in renal dialysis patients. Effect on cellular immune response.

The effect of blood transfusions, given in low number (less than 5), on the immune response of renal dialysis patients was studied. A significantly lowered response of lymphocytes to mitogen stimulation was observed in patients after as few as one, two or three transfusions, depending on the patient. This led to an increased delta 48/delta 0 ratio reflected by the enhanced response of the cells following delayed addition of suboptimal dose of mitogen. There was no modification of the ratio of helper/inducer to suppressor/cytotoxic T cells subsets (OKT4/OKT8). The use of such simple in vitro tests in a strict protocol of transfusions could allow an adequate follow-up thereby limiting the risks of sensitization. These results demonstrate that important phenomena affecting patients' immune response are turned on following even a low number of transfusions in the majority of uremic patients. This could probably be related to the beneficial effects of blood transfusions on the kidney allograft survival already described.

Adult↗
PubMed1984

Radioautographic study of binding and internalization of corticotropin-releasing factor by rat anterior pituitary corticotrophs.

In order to identify the anterior pituitary cell type(s) containing corticotropin-releasing factor (CRF) receptors and to study the internalization processes of this peptide by the target cells, radioautography was performed on rat anterior pituitaries removed at specific intervals (2-60 min) after intracarotid injection of [125I]iodo-CRF into intact and adrenalectomized female rats. In intact animals, all corticotrophs were labeled, whereas in the adrenalectomized animals about 80% of the hypertrophied corticotrophs (adrenalectomy cells) were. In control animals injected with both iodinated CRF and an excess of unlabeled peptide, no specific reaction could be detected. The time-course study in intact animals showed that 2 min after injection most silver grains were found over or within 160 nm of the plasma membrane. At the 5-min time intervals, grains were observed both over the plasma membrane and within the cytoplasm, associated with lysosomes, and the Golgi apparatus. Fifteen minutes after injection, grains were mostly found over lysosomes and the Golgi apparatus, whereas at the longest time intervals (30 and 60 min) almost no labeling could be detected. The results obtained in this study indicate that in the anterior pituitary CRF receptors are restricted to corticotrophs (as identified by electron microscopy) and that, after binding to the plasma membrane, CRF is rapidly internalized to Golgi elements and lysosomes.

Animals↗
PubMed1984

Characterization and localization of vasoactive intestinal peptide receptors in the rat lung.

Experiments were performed to characterize vasoactive intestinal peptide (VIP) receptors in rat lung and to study their localization by means of light and electron microscope autoradiography. [125I]Iodo-VIP binding to lung homogenate was inhibited by synthetic VIP, [Val5]secretin, secretin, and 7-27 secretin with half-maximal inhibition (ID50) values of 1.62, 13, 121 nmol/liter and up to 0.1 mmol/liter, respectively. The relative potency of [Val5]secretin and 7-27 secretin to displace the tracer indicated that [125I]iodo-VIP binds to specific VIP receptors. Kinetic studies showed two sites of binding, a site of high affinity with equilibrium dissociation constant (KD) values of 0.32 +/- 0.09 nM and Bmax of 88.7 +/- 28.6 fmol/mg protein and a lower affinity binding site with a KD value of 23.0 +/- 2.9 mM and Bmax of 584 +/- 136.9 fmol/mg protein. The localization of VIP receptors was performed by radioautography both in vivo after iv injection of [125I]iodo-VIP and in vitro by the direct application of the radiolabeled peptide to cryostat sections of unfixed lung tissue. After iv injection of label, silver grains were detected only over alveoli. Electron microscopy indicated that radioactivity was mostly associated with alveolar capillaries. In vitro localization studies showed specific binding not only to alveoli but also to bronchi. These studies suggest that VIP can act at different sites and that the peptide could gain access to alveoli via the general circulation.

Animals↗
PubMed1984

[The coexistence of neuropeptides and catecholamines in the adrenal gland. Research on paracrine effects on adrenal cortex cells].

The aim of the present review was to compare in mammals and amphibians the data concerning the presence of neuropeptides in the chromaffin cells and the possible action of these substances on adrenocortical cell function. Major homologies are to be found concerning the coexistence in chromaffin granules of catecholamines, Met-and Leu-enkephalins, and their precursor, proenkephalin A. However, the inhibitory action that might be exerted by enkephalins in vitro on corticosteroid production in mammalian adrenal gland, does not occur in amphibia. Dynorphin has been isolated in bovine adrenal medulla extracts; the presence of this opioid peptide has not been reported yet in amphibian interrenal tissue. All chromaffin cells of the frog interrenal gland contain VIP-like immunoreactivity whereas this neuropeptide is not contained in the adrenal medulla of mammals, exept in certain pheochromocytomas. In the frog, VIP, Metenkephalin and catecholamines are co-sequestered in the same chromaffin granules. In addition, synthetic porcine or chicken VIP stimulate in vitro the secretion of corticosteroids by frog interrenal fragments. In mammals, the steroidogenic action of VIP has been observed exclusively in tumor cell lines. The existence of somatostatin has been demonstrated in the human adrenal medulla and in pheochromocytomas, but not in amphibia. Somatostatin has been found to inhibit the response of adrenocortical cells to angiotensin II in mammals. A similar effect of somatostatin was not observed in amphibia. The coexistence of VIP and catecholamines in frog chromaffin granules and the stimulatory effect exerted by VIP on corticosteroidogenesis suggest that, in these animals, VIP may be co-liberated with noradrenaline during stress conditions, and thus may act locally on adrenocortical cells to stimulate corticosteroid secretion.

Adrenal Cortex↗
PubMed1984

[Occurrence and nature of hyperamylasemia in chronic alcoholics].

The purpose of this work was: a) the prospective study of the prevalence of hyperamylasemia in 100 patients with chronic alcoholism; b) the determination of the serum isoamylase distribution in patients with hyperamylasemia by an inhibitor assay; c) the search of the origin of elevated serum isoamylase S. Moderate hyperamylasemia was found in 15 patients. The importance of alcohol abuse, the prevalences of cirrhosis and smokers were not statistically different from those observed in normoamylasemic patients. After one week of hospitalization, serum amylase was still elevated in 11 of 14 alcoholic patients. Hyperamylasemia was due to an increase in the isoamylase P in 5 cases, in the isoamylase S in 7 cases, and in both forms in 3 cases. Activities of serum lipase and isoamylase P were roughly parallel. Only two out of 8 patients with elevated isoamylase P had chronic pancreatitis. The salivary origin of elevated isoamylase S was suspected in only one out of 10 patients. This work shows that the origin of moderate hyperamylasemia, observed in alcoholic patients, is often extrapancreatic. It is suggested that the dosage of serum lipase simpler than that of isoamylases, may be routinely used in chronic alcoholic patients for diagnostic purposes.

Adult↗
PubMed1984

[Adenoma of the liver in man].

The authors report the case of a 28-year-old man with a solitary adenoma of the liver. The tumor was detected because of a raised erythrocyte sedimentation rate and serum fibrinogen. Review of the literature shows that adenoma of the liver is an uncommon tumor in man since only 30 other cases have been reported. The tumor is often multiple (55 p. 100) and the clinical manifestations are quite different from those observed in women: the adenoma is often asymptomatic (45 p. 100) and rupture is rare (10 p. 100). Androgens seem to be implicated in the development of adenoma in man since 8 out of 31 patients had received androgens for a long period of time; androgens also seem to favor the tumor's rupture.

Adult↗
PubMed1984

[Phenotype study of blood T lymphocytes in alcoholic hepatopathies].

Peripheral blood T lymphocytes and T lymphocytes subsets have been quantified by an indirect immunofluorescence technique using monoclonal antibodies, in 10 patients with fatty liver, 8 with acute alcoholic hepatitis (AAH), 10 with inactive cirrhosis and 7 with cirrhosis and AAH. Twenty normal subjects were studied as controls. As compared to controls (1.81 +/- 0.56 10(9)/l), we found a reduced number of peripheral T lymphocytes (OKT3+) in patients with inactive cirrhosis (0.98 +/- 0.45, p less than 0.001) and in patients with cirrhosis and AAH (1.22 +/- 0.51, p less than 0.02). The OKT4 to OKT8 ratio was normal in patients with fatty liver or inactive cirrhosis, but it was significantly higher in patients with AAH with or without cirrhosis (2.83 +/- 0.79, p less than 0.01, and 2.10 +/- 0.56, p less than 0,02, respectively) than in controls (1.68 +/- 0.24). In both groups, this increased ratio was due to a decreased proportion of OKT8+ circulating lymphocytes (19.2 +/- 6.7 p. 100, p less than 0.01, and 21.8 +/- 4.6 p. 100, p less than 0.02, respectively) when compared to controls (27.1 +/- 4.1 p. 100). The T-cell imbalance observed in patients with liver cell necrosis may be of importance in the pathogenesis of alcoholic liver disease.

Adult↗
PubMed1984

[Enemas].

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Enema↗
PubMed1984

[Value of echotomography for the diagnosis of lithiasis of the common bile duct].

The accuracy of ultrasonography (US) for the diagnosis of cholelithiasis and for dilatation of the intra- and extra-hepatic biliary tree is well known. However, the value of US for the diagnosis of common bile duct stones remains poorly defined. We performed a prospective study in 100 patients who were referred for endoscopic retrograde cholangiopancreatography (ERCP); all the examinations were carried out by the same sonographist in the 24 h preceding the ERCP. Fifty patients had choledocholithiasis, 20 patients had obstruction of the bile ducts without lithiasis and the common bile duct (CBD) was free in 30 patients. The sensitivity of US for the diagnosis of choledocholithiasis was 40 p. 100, the specificity 90 p. 100. The positive and negative predictive values of the "CBD stone" sign was 80 p. 100 and 60 p. 100 respectively. In a total of 30 false negatives, the CBD could not be explored in 4 cases, dilatation of the CBD was missed in one case, and obstruction of the CBD by an other disease was diagnosed in 2; in all the other cases, US was able to appreciate the CBD size as well as the ERCP. In the 20 patients with an obstructed CBD but without choledocholithiasis, US diagnosed a stone in 5 cases. Age, serum bilirubin, existence of a previous cholecystectomy, technical difficulties, stone size were comparable in patients with true positive tests and in patients with false negative tests. However the diagnosis of choledocholithiasis was more frequently achieved in patients with dilated CBD over 10 mm (p less than 0.05) and in patients with multiple stones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

[Stenosis of the left hepatic duct with intrahepatic lithiasis: treatment by the percutaneous transhepatic approach].

The authors report the case of a 78-year-old woman suffering from cholangitis secondary to intrahepatic biliary stricture and intrahepatic lithiasis. Successful management consisted of successive percutaneous transhepatic internal-external biliary drainage, balloon dilatation of the stricture and gallstone mobilisation and removal through the stricture. No complications were noted.

Aged↗
PubMed1983

Demonstration of contacts between proopiomelanocortin neurons in the rat hypothalamus.

The relationships between proopiocortin neurons have been studied in the rat hypothalamic arcuate nucleus by immunocytochemistry. At the light microscopic level, contacts between immunostained endings and cell bodies or dendrites were frequently observed. At the electron microscopic level, stained nerve terminals were seen making symmetrical synaptic contacts with labeled dendrites and cell bodies. These observations are the first indication that neurons producing the same peptides can have contacts between themselves. This provides morphological evidence for autoregulation of neuropeptide systems.

Adrenocorticotropic Hormone↗
PubMed1983

Immunocytochemical localization of corticotropin-releasing factor-like immunoreactivity in the human hypothalamus.

In order to study the distribution of corticotropin-releasing factor-like immunoreactivity (CRF-LI) in the human hypothalamus, an immunocytochemical localization of this neurohormone was performed. Using antibodies developed against ovine CRF, we have localized CRF-LI in parvicellular neuronal cell bodies in the paraventricular nucleus. Immunostained fibers were observed in the median eminence, the pituitary stalk and the posterior pituitary. These results suggest that immunoreactive material related to ovine CRF is present in the human hypothalamus with a distribution similar to that observed in the rat.

Corticotropin-Releasing Hormone↗
PubMed1983

Coexistence of vasoactive intestinal peptide and enkephalins in the adrenal chromaffin granules of the frog.

The chromaffin cells of the frog adrenal gland were studied at the electron microscopic level by means of the immunoperoxidase technique. Using specific antibodies against Met-enkephalin, Leu-enkephalin and vasoactive intestinal peptide (VIP), the coexistence of the three neuropeptides in the chromaffin cells was demonstrated. Furthermore, all three peptides were co-located in the 200-400 nm dense-core vesicles which also stained for dopamine-beta-hydroxylase. These results, which suggest concomitant release of catecholamines and neuropeptides by the chromaffin cells, support the concept that VIP is involved in the stimulation of adrenal steroid secretion during stress conditions.

Adrenal Medulla↗
PubMed1983

Biological and immunological characterization of alpha-melanocyte-stimulating hormone (alpha-MSH) in two neuronal systems of the rat brain.

Recent immunocytochemical studies have demonstrated the existence of two different neuronal systems containing alpha-MSH-like material in the brain: one originating from the arcuate nucleus and the other one from the dorsolateral hypothalamus. The aim of the present study was to further characterize alpha-MSH in these two discrete regions of the rat diencephalon. Intracerebroventricular administration of colchicine resulted in a marked decrease in the number of ACTH and beta-endorphin nerve fibers and a significant reduction in ACTH and beta-endorphin content in the dorsolateral hypothalamus. Conversely, colchicine treatment did not alter alpha-MSH, ACTH or beta-endorphin content in the arcuate nucleus and did not significantly affect alpha-MSH concentration in the dorsal region. Reverse-phase high-performance liquid chromatography showed that the major alpha-MSH-like compound localized in the dorsal hypothalamus co-migrated exactly with synthetic alpha-MSH, whereas the arcuate nucleus contained 5 peptides cross-reacting with alpha-MSH antibodies, 4 of them being different from standard alpha-MSH. Significant amounts of biologically active melanotropin, which migrated on Sephadex G-25 columns like synthetic alpha-MSH, were also detected in both the arcuate nucleus and dorsolateral hypothalamus. Taken together, these data demonstrate that the alpha-MSH cell bodies located in the dorsolateral hypothalamus specifically produce authentic alpha-MSH, whereas the alpha-MSH cell bodies in the arcuate nucleus also contain ACTH, beta-endorphin and several peptides immunologically related but not identical to alpha-MSH.

Adrenocorticotropic Hormone↗