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Biomedical subjects

G Pelletier

Publications and source records attributed to G Pelletier.

At least 487 records · Page 27Linked to original sources
PubMed1987

Suppression by relevant allergen of the spontaneous in vitro production of rye group I specific IgE antibodies by human peripheral blood lymphocytes.

The production in vitro of rye Group I specific IgE antibodies (rye I specific IgE Ab) by human peripheral blood lymphocytes (PBL) was examined. A sensitive enzyme-linked immunosorbent assay was developed which allowed the detection of rye I specific IgE Ab without interference from other immunoglobulin classes. A significant net synthesis of rye I specific IgE Ab by PBL from atopic subjects was detected only during the pollen season, which could not be observed with PBL from non-atopic donors whenever tested. This active synthesis in vitro of IgE antibodies by PBL from atopic patients in season was suppressed when PBL were pre-incubated with the relevant antigen. Furthermore, we are reporting data suggesting an inhibition of the passive release of preformed rye I specific IgE Ab from cells by the specific allergen.

Antibody Specificity↗
PubMed1987

[Prognosis of acute viral hepatitis in patients with alcoholic cirrhosis].

We report 20 cases of alcoholic cirrhosis with superimposed episodes of acute viral hepatitis. Four had acute type B hepatitis and 16, presumed non A non B hepatitis. Before hepatitis, 17 patients had stopped drinking and only four had a complicated cirrhosis. Eighteen patients had received a blood transfusion within the 6 months before the occurrence of hepatitis (mean: 52 days). All patients developed jaundice, 7 encephalopathy, and 5 ascites. The ASAT/ALAT ratio was greater than 1 in 18 patients. Two patients died of hepatic failure. Follow-up was known in 17 of the 18 surviving patients: in all patients jaundice disappeared and transaminases returned to values less than 3 times the upper limits of normal. In our experience, the prognosis is good when viral hepatitis occurs in patients with non complicated alcoholic cirrhosis.

Acute Disease↗
PubMed1986

Localization of atrial natriuretic factor (ANF)-immunoreactive material in the hypothalamo-pituitary complex of the frog.

The presence of atrial natriuretic factor (ANF)-like material in the hypothalamo-pituitary complex of the frog (Rana ridibunda) was studied by means of indirect immunofluorescence and immunogold techniques. In the hypothalamus, numerous ANF-positive cell bodies were located in the preoptic nucleus, the lateral forebrain bundle and the dorsal infundibular nucleus. The ventral infundibular area and the median eminence contained only ANF-immunoreactive fibers. A dense network of fibers and nerve terminals was observed in the neural lobe of the pituitary. Scarce nerve endings were also noted in the intermediate lobe whereas ANF-like immunoreactivity was totally absent in the anterior lobe of the pituitary. At the ultrastructural level, positive material appeared restricted to dense core vesicles (about 100 nm in diameter). These results demonstrate that an ANF-like substance is contained in nerve terminals of the frog pars nervosa, and support the hypothesis that ANF may exert a physiological role in the control of release of neurohypophyseal peptides.

Animals↗
PubMed1986

Demonstration of a neuropeptide Y (NPY)-like immunoreactivity in the pigeon retina.

The distribution of neuropeptide Y (NPY)-like immunoreactivity in the pigeon retina was investigated by fluorescence immunohistochemistry. NPY-positive cells were found in central and peripheral retina. NPY somata were located in the proximal portion of the inner nuclear layer and their processes directed to the inner plexiform layer where they ramified in 3 immunoreactive bands. NPY might play a role as a neurotransmitter or neuromodulator in the pigeon retina.

Animals↗
PubMed1986

Neuropeptide Y in the intermediate lobe of the frog pituitary acts as an alpha-MSH-release inhibiting factor.

The presence of neuropeptide tyrosine (NPY) in the intermediate lobe of the frog pituitary was demonstrated using indirect immunofluorescence, the immunogold technique and a specific radioimmunoassay combined with high pressure liquid chromatography (HPLC). A high density of NPY-containing fibers, was found among the parenchymal cells of the intermediate lobe. These fibers originated from the ventral infundibular nucleus, travelled via the median eminence to the pars intermedia. At the electron microscopic level, NPY-like material was found exclusively in nerve fibers where the product of the immunoreaction was associated to dense-core vesicles. High concentrations of NPY-like peptide were found in neurointermediate lobe extracts. After Sephadex G-50 gel filtration the major peak of immunoreactive material appeared to co-elute with synthetic porcine NPY. Conversely, HPLC analysis revealed that the NPY-like peptide of the frog pituitary had a retention time shorter than the porcine NPY. The localization of NPY-like material in the pars intermedia suggested a possible role of NPY in the regulation of melanotropic cell secretion. In fact, graded concentrations of synthetic NPY induced a dose-dependent inhibition of alpha-melanotropin (alpha-MSH) release in vitro. The lack of effect of a dopaminergic antagonist on NPY-induced alpha-MSH release inhibition demonstrated that the local dopaminergic system could not account for the NPY action. These results indicate that NPY located in the hypothalamo-hypophyseal system of the frog may act as a melanotropin-release inhibiting factor.

Animals↗
PubMed1986

The role of dopamine in the control of neuropeptide Y neurons in the rat arcuate nucleus.

In order to determine the role of dopamine (DA) on neuropeptide Y (NPY) neurons in the arcuate nucleus of the rat hypothalamus, we evaluated the effects of alpha-methylparatyrosine (alpha-MPT), an inhibitor of catecholamines biosynthesis, and haloperidol, a dopaminergic antagonist, on NPY immunoreactive neurons. The two drugs used produced in the arcuate nucleus the appearance of a large number of NPY-containing neuronal bodies which are normally absent in control animals. The density of stained fibers were not significantly modified. These results suggest that DA can exert some negative regulation of NPY neurons activity in the arcuate nucleus.

Animals↗
PubMed1986

Striatal neuropeptide Y neurones are under the influence of the nigrostriatal dopaminergic pathway: immunohistochemical evidence.

Selective unilateral 6-hydroxydopamine lesion of the nigrostriatal dopaminergic neurones in rats resulted, 12 to 90 days later, in a marked increase in the number of neuropeptide Y (NPY)-immunoreactive perikarya in the ipsilateral deafferented striatum compared to the contralateral intact side in the same animal and to both sides in control animals. The staining intensity of most positive cells also appeared to be enhanced in the deafferented striatum. These effects which can be interpreted as resulting from an increase in the intraneuronal levels of NPY may be accounted for by an increased production or a decreased metabolization of the peptide in the striatum deafferented from its dopaminergic input. The results therefore provide morphological evidence that the NPY-containing neuronal system of the striatum may undergo tonic influence from nigrostriatal dopaminergic afferents.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Allergenicity and cross-reactivity of rye grass pollen extracts revealed by monoclonal antibodies.

Using monoclonal antibodies the immunogenic and allergenic characteristics of rye Group I were redefined by SDS-PAGE analysis and immunoblotting. The purified rye Group I from NIH possesses a major component of approximately 34000 Da against which most of the sera from grass-sensitive patients and none from non-atopic volunteers contain specific IgE antibodies. Monoclonal antibodies to rye Group I were raised and used to purify the antigen and to verify the cross-reactivity between grass extracts. The 3 monoclonal antibodies studied recognized different components of timothy grass and 2 of them recognized kentucky june grass but none recognized components of ragweed extracts.

Allergens↗
PubMed1986

Effects of monosodium L-glutamate administration on neuropeptide Y-containing neurons in the rat hypothalamus.

Immunocytochemical localization of neuropeptide Y (NPY) was performed in the hypothalamus of rats of which the arcuate nucleus had been destroyed with monosodium L-glutamate in the neonatal period. The treatment produced a disappearance of most of the NPY cell bodies normally found in the arcuate nucleus. The concentration of fibers was decreased in the paraventricular nucleus, but not in the other hypothalamic nuclei. The treatment also induced the appearance of a large number of immunoreactive cell bodies in the paraventricular nucleus. These results strongly suggest that arcuate NPY neurons are projecting to the paraventricular nucleus and that the arcuate nucleus probably exerts some inhibitory tonic influence on NPY paraventricular neurons.

Animals↗
PubMed1986

Localization and identification of alpha-melanocyte-stimulating hormone (alpha-MSH) in the frog brain.

The distribution of alpha-melanocyte-stimulating hormone (alpha-MSH) in the central nervous system of the frog Rana ridibunda was determined by immunofluorescence using a highly specific antiserum. alpha-MSH-like containing perikarya were localized in the infundibular region, mainly in the ventral hypothalamic nucleus. A rich plexus of immunoreactive fibers directed towards the ventral telencephalic region was detected. Reverse-phase high-performance liquid chromatography and radioimmunoassay were used to characterize alpha-MSH-like peptides in the frog brain. Chromatographic separation revealed that immunoreactive alpha-MSH coeluted with synthetic des-N alpha-acetyl alpha-MSH, authentic alpha-MSH and their sulfoxide derivatives. The heterogeneity of alpha-MSH-like material in the frog brain was in marked contrast with the figure observed in the intermediate lobe of the pituitary gland where only des-N alpha-acetyl alpha-MSH is present. These findings support the existence of discrete alpha-MSH immunoreactive neurons in the frog brain containing both desacetyl and authentic alpha-MSH.

Animals↗
PubMed1986

Light-microscopic immunocytochemical localization of growth hormone-releasing factor in the human hypothalamus.

The distribution of growth hormone-releasing factor (GRF)-like immunoreactivity in the human hypothalamus was studied by light-microscopic immunocytochemistry. With antibodies that we developed against synthetic human pancreatic GRF (hpGRF), we localized GRF immunoreactivity in neuronal cell bodies that were observed only in the infundibular (arcuate) nucleus. Immunostained nerve fibers were found in large numbers in the neurovascular zone of the median eminence, in the proximal portion of the pituitary stalk and in periventricular areas. These localizations are in agreement with those of studies recently performed in other species and strongly suggest that GRF can be released into the capillaries of the pituitary portal plexus to reach the anterior pituitary gland. The projections of GRF neurons in extra-infundibular regions suggest that GRF can also act as a neuromodulator or neurotransmitter in the hypothalamus.

Adult↗
PubMed1986

Chronic active hepatitis associated with liver-kidney microsomal antibody of an autoimmune type. Two familial cases.

We report the findings in two sisters with active cirrhosis and an anti-liver-kidney microsomal antibody (anti-LKM) of the autoimmune type. This unusual disease is characterized by the presence of high levels of antibodies that react with the smooth and rough endoplasmic reticulum of the liver and other tissues. Our patients had the usual features of chronic hepatitis associated with presence of antibodies: they were young girls, they had anti-LKM antibodies of autoimmune type persisting at a high titer during the whole course of the disease, but with no smooth muscle antibodies; one had a low level of IgA. The occurrence of two cases in the same family has not yet been reported and is probably not coincidental because of the rare occurrence of this disease.

Adolescent↗
PubMed1986

Prospective study of clinical and biochemical features of symptomatic choledocholithiasis.

One hundred consecutive patients were prospectively studied to assess the clinical and biochemical features of symptomatic choledocholithiasis. Biochemical tests were performed during the three days following the onset of symptoms. Pain was the most frequent symptom of choledocholithiasis, observed in 75% of the patients, but rarely occurred alone (12%). Clinical symptoms were not different according to age. High serum gamma glutamyl transpeptidase and alkaline phosphatase were the most frequent biochemical abnormalities in patients with symptomatic choledocholithiasis: they were increased in 94 and 91% of cases, respectively. Only one patient had no biochemical abnormality. Serum transaminases could reach very high levels just as in hepatitis. Biochemical data did not differ regardless of whether the common bile duct was enlarged or not. Biochemical abnormalities had been studied over the first 10 days of spontaneous evolution in 25 patients while choledocholithiasis persisted: serum bilirubin and transaminases significantly decreased while serum gamma glutamyl transpeptidase, alkaline phosphatase, and amylase remained unchanged. These results indicate that, in patients with suggestive symptoms, choledocholithiasis is unlikely in the absence of biochemical abnormalities in the first three days following the onset of symptoms.

Adult↗
PubMed1986

pH of ascitic fluid: diagnostic and prognostic value in cirrhotic and noncirrhotic patients.

The pH measurements of 185 samples of ascitic fluid in 169 cirrhotic and 16 noncirrhotic patients were analyzed to assess their diagnostic and prognostic value. The 169 cirrhotic patients were divided into four groups: sterile ascites (group 1), spontaneous bacterial peritonitis (group 2), probable spontaneous bacterial peritonitis (group 3), and bacterascites (group 4). Mean ascitic fluid pH values were lower (p less than 0.001) in patients of groups 2 (7.24 +/- 0.17) and 3 (7.34 +/- 0.11) than in patients of groups 1 (7.44 +/- 0.06) and 4 (7.45 +/- 0.08), but there was an important overlap between these groups. Mean arterial-ascitic fluid pH gradient values were higher (p less than 0.001) in patients of groups 2 (0.21 +/- 0.16) and 3 (0.10 +/- 0.13) than in patients of groups 1 (0.02 +/- 0.05) and 4 (0.02 +/- 0.05). This gradient had a better discriminant power than ascitic fluid pH alone. Sensitivity, specificity, positive and negative predictive value, and diagnostic accuracy for the diagnosis of certain or probable spontaneous bacterial peritonitis were, respectively, 47%, 99%, 88%, 89%, and 89% for ascitic fluid pH values less than 7.32; 66%, 99%, 91%, 93%, and 92% for arterial-ascitic fluid pH gradient values greater than 0.10; and 97%, 96%, 86%, 99%, and 96% for polymorphonuclear cell count greater than 75/microliter. Ascitic fluid pH values appeared to have a high prognostic value, as 6 of 7 cirrhotic patients with ascitic fluid pH values less than 7.15 died rapidly. Low ascitic fluid pH values were found in patients with malignant and pancreatic ascites and tuberculous peritonitis but not in patients with cardiac ascites. We conclude that in cirrhotic patients with certain or probable spontaneous bacterial peritonitis (a) arterial-ascitic fluid pH gradient measurements had a slightly higher diagnostic value than ascitic fluid pH measurements but a slightly lower diagnostic value than polymorphonuclear cell count and (b) ascitic fluid pH measurements had a high prognostic value. In noncirrhotic patients, ascitic fluid pH and arterial-ascitic fluid pH gradient measurements had a poor diagnostic value.

Adolescent↗
PubMed1986

Comparative effects of corticotropin-releasing factor, arginine vasopressin, and related neuropeptides on the secretion of ACTH and alpha-MSH by frog anterior pituitary cells and neurointermediate lobes in vitro.

The ability of corticoliberin (CRF), urotensin I, sauvagine, arginine-vasopressin (AVP), and mesotocin to stimulate ACTH release by frog anterior pituitary cells and alpha-melanotropin (MSH) by frog neurointermediate lobe was studied in vitro using a perifusion technique. CRF and AVP were found to be potent stimulators of ACTH secretion, whereas urotensin I and sauvagine were totally inactive. In opposition to recent findings in the rat. CRF did not modify alpha-MSH secretion by the frog neurointermediate lobe. Mesotocin, which is present in the parenchymal cells of the frog pars intermedia, had no effect on alpha-MSH release in vitro. No potentiation of CRF-induced ACTH release was observed when anterior pituitary cells were incubated with a combination of AVP and CRF. Together with the recent elucidation of a CRF-like molecule in the frog diencephalon, these results suggest that, in Amphibia, CRF and AVP exert their stimulatory action specifically on distal lobe corticotrophs.

Adrenocorticotropic Hormone↗