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Biomedical subjects

G Pelletier

Publications and source records attributed to G Pelletier.

At least 505 records · Page 28Linked to original sources
PubMed1986

Increased compound 48/80 induced local histamine release from nonlesional skin of patients with chronic urticaria.

Histamine released from skin mast cells in normal skin sites of patients with idiopathic chronic urticaria (CU) and normal volunteers was assessed with the skin chamber technique. Small amounts of histamine were spontaneously and continuously released during the 4-hour observation in both groups but were twofold greater in patients with CU. In addition, histamine levels were significantly more elevated in sites challenged with compound 48/80 than in unstimulated sites. Patients with CU differed from normal volunteers in that histamine release induced by 48/80 compound was significantly greater at 1 and 2 hours after challenge. The number of mast cells and the histamine content of the skin did not differ in the two groups. These observations could suggest a functional defect at the mast cell level rather than a difference in their numbers.

Adolescent↗
PubMed1986

Distribution of epidermal growth factor receptors in the rat ovary.

The distribution of epidermal growth factor (EGF) was studied in the ovary using light microscope radioautography which was performed at different time intervals (2-60 min) after intravenous (i.v.) injection of [125I]EGF into adult rat at random stages of the estrous cycle and also after topical localization of iodinated EGF on slide-mounted frozen ovarian sections. After i.v. injection of label, the labeling was mostly observed in the theca interna cells of secondary, preovulatory and atretic follicles and luteal cells of corpus luteum. Primordial and primary follicles did not show any significant labeling. The time-course study performed on luteal cells showed that, 2 min after injection, most silver grains were found at the periphery of the cells. At the 10 min time interval, silver grains were found both at the periphery and over the cytoplasm of these cells. The number of grains was very reduced over the cytoplasm at the 60 min time interval. In the in vitro study, a positive radioautographic reaction was seen in the same cellular elements as found in vivo, with the additional labeling of the granulosa cells of growing and preovulatory follicles. Control experiments indicated that the radioautographic labeling was due to specific interaction of [125I]EGF with its receptor. These results clearly indicate that EGF binding sites are present in luteal, thecal and granulosa cells, and provide support for the inhibitory and stimulatory actions of EGF on different parameters of ovarian cells.

Animals↗
PubMed1986

Autoradiographic localization of beta-adrenergic receptors in the rabbit pituitary.

The localization and characterization of beta-adrenergic receptors in the rabbit pituitary have been studied using [125I]cyanopindolol as a specific ligand. Slide-mounted frozen sections were used for the autoradiographic localization and characterization of beta-adrenergic receptors. The displacement curves obtained from optical density of radioautograms or counting of scraped off sections demonstrated that beta-adrenergic receptors were mostly of the beta 2-subtype and highly concentrated in the intermediate lobe. Low concentrations of beta 2-adrenergic receptors were also found to be uniformly distributed in the anterior and posterior lobes. These results suggest that epinephrine and/or norepinephrine might play a physiological role in the regulation of the secretion of not only the intermediate lobe but also the anterior and posterior lobes of the rabbit pituitary.

Animals↗
PubMed1986

Influence of pregnancy, lactation, litter size and diet energy density on the pancreas of sows.

In a first experiment, each of 52 sows having raised one litter was randomly assigned to one of the five following groups: control (nongravid) for pregnancy (CP), 110 d pregnancy (P110), control (nongravid) for lactation (CL), 4 wk lactation with 8 (L8) and with 12 (L12) piglets. In a second experiment, each of 36 sows having raised three litters was randomly assigned to the following groups: control group (nongravid) fed a low energy density 1% tallow diet (CLED) and two lactation groups, one fed the low energy density diet (LLED) and the other fed a high energy density 10% tallow diet (LHED). At slaughter the pancreas was excised, freed from fat and weighed. Fragments were homogenized for evaluation of protein, amylase, chymotrypsin, RNA and DNA content. Pancreas weight was not affected by pregnancy, lactation or litter size. Pancreatic cellular mass (15.2%), amylase (42.6%) and chymotrypsin (34.6%) concentrations were smaller among pregnant sows (P110) than among their controls (CP). Amylase concentration tended to be lower among the L12 than among the L8 sows (P = 0.067). Sows fed the high energy diet (LHED) had greater pancreas weight (15.3) and chymotrypsin activity (48.1%) than those fed the low energy diet (LLED). Pregnancy, lactation, litter size and dietary energy density during lactation all had a significant effect on the pancreas of the sow.

Animal Feed↗
PubMed1986

Distribution of epidermal growth factor binding sites in the adult rat liver.

The localization of epidermal growth factor (EGF) receptors was studied in the liver by use of light microscope autoradiography performed at different time intervals (2-60 min) after intravenous injection of 125I-EGF into adult rat. The results revealed a substantial binding of EGF to parenchymal cells of the liver. Control experiments indicated that the autoradiographic labeling was due to specific interaction of 125I-EGF with its receptor. A very steep portal-to-central lobular concentration gradient for 125I-EGF uptake was observed. The time course study performed on parenchymal cells of periportal regions of lobules showed that, at the 2-min time interval, most silver grains were found at the periphery of these cells and that the maximal values were reached 7 min after injection. After, the number of grains decreased progressively and their localization in the cytoplasm indicated the internalization of the ligand. The present results demonstrate that EGF injected into the general circulation preferentially binds to hepatocytes located in the periportal area and is rapidly internalized.

Animals↗
PubMed1986

Family dysfunction and the psychological impact of child sexual abuse.

This paper presents the view that family dysfunction in intra- and extra-familial child sexual abuse can be considered apart from the sexual trauma and can be seen as having important independent psychological consequences. Family dynamics are discussed as they relate to both types of sexual abuse and as they relate to the context of disclosure of the events. A direct link is suggested between such dynamics and the psychological problems experienced by the child victims. Recommendations for research and therapy are also made.

Adolescent↗
PubMed1986

Internalization and subcellular distribution of radiolabeled somatostatin-28 in mouse anterior pituitary tumor cells.

The ACTH-secreting mouse AtT-20/D16-16 (AtT-20) tumor corticotroph possesses receptors for the tetradecapeptide somatostatin (S-14) to which the 14-amino acid N-terminal extension somatostatin-28 (S-28) also binds. When AtT-20 cells are exposed to either S-14 or S-28 for extended periods of time, a marked decrease in S-14 receptor density is observed. Since receptor down-regulation is frequently associated with internalization of ligand and/or receptor, the present study was designed to establish whether AtT-20 cells could in fact internalize S-28 and to determine the subcellular localization of internalized peptide. Cells were incubated in the presence of [Leu8, D-Trp22,125I-Tyr25] S-28 for 1, 4, and 18 h; washed with PBS; and harvested. Cell pellets were fixed, sectioned, and analyzed by light and electron microscopic autoradiography. Uptake of radiolabeled S-28 (90% of all cells) was inhibited by 80% when unlabeled S-14 was coincubated with [125I]S-28. Of the cell compartments examined, plasma membrane, secretory granules, lysosomes, Golgi apparatus, and nuclear membrane all had distinct time-dependent labeling patterns. Plasma membranes were maximally labeled 1 h after exposure to [125 I] S-28. Secretory granule and lysosomal labeling was observed within 1 h, but was maximal after 18 h of exposure. Labeling of the granule compartment preceded that of the Golgi apparatus. The nuclear compartment (membranes plus nuclei) was also labeled significantly after 18 h of incubation. However, the nuclear membrane itself was labeled after only 1 h of exposure to the ligand. The data suggest that radiolabel is transferred from the plasma membrane to the intracellular organelles as a function of exposure time. Labeling of the secretory compartment suggests that granules may bind and protect internalized peptide from lysosomal degradation. Appearance of label in the nuclear compartment suggests that S-28 (and S-14) may have effects on transcriptional activity in AtT-20 cells.

Animals↗
PubMed1986

Distribution of epidermal growth factor binding sites in the adult rat adrenal gland by light microscope autoradiography.

The distribution of epidermal growth factor (EGF) receptors was studied in the adrenal gland using light microscope autoradiography which was carried out 2 min after intravenous (iv) injection of [125I]EGF into adult rat. At the light microscope level, the labelling was found over the cells of the capsule and adrenal medullary chromaffin cells. No specific labelling of the steroid-secreting cells was observed. Control experiments indicated that the autoradiography reaction was due to specific interaction of [125I]EGF with its receptor. These results clearly indicate that EGF receptors are present in the majority of the adrenal medulla cells. They suggest that EGF may exert a physiological role in the regulation of rat adrenal medulla.

Adrenal Glands↗
PubMed1986

Radioautographic localization and regulation of the insulin receptors in rat testis.

Luteinizing hormone (LH) is involved in maintenance of the insulin receptor in rat Leydig cells. In the cryptorchid model, spontaneous LH elevation increases insulin binding in Leydig cell membrane; this result is confirmed by the number of insulin receptors determined by radioautography. Administration of testosterone or LH-RH to control or cryptorchid rats lower insulin binding in testis membranes indicating the key role of LH. Isolated Leydig cells respond in vitro to LH by increasing their insulin binding. Localization and specificity of this binding has been studied by radioautography and we have demonstrated the preferential localization of insulin receptor in Leydig cells vs tubular cells. We conclude that insulin plays a synergistic role with LH on steroidogenesis via a specific membrane receptor which number appears modulated by pituitary LH.

Animals↗
PubMed1986

Immunological and non-immunological release of leukotrienes and histamine from human nasal polyps.

Nasal polyps were obtained from 22 patients undergoing polyp surgery. They were chopped into fragments of approximately 2 mm2, washed free of blood, and passively sensitized with serum from timothy allergen sensitive patients (RAST 30-40%), then, challenged with timothy allergen. Analysis of the incubation medium after a 30 min challenge as assessed by reversed phase high performance liquid chromatography and bioassay revealed the presence of leukotriene (LT) LTB4, LTC4, LTD4 and LTE4 (29 +/- 9, 6.6 +/- 3, 62 +/- 13 & 86 +/- 23 pmol/g tissue wet weight, respectively). The human nasal polyps also released histamine which reached a maximum after approximately 5 min (2.8 +/- 1.28 nmol/g tissue), as measured by radioenzymatic assay. A similar profile of leukotrienes and histamine release was observed when the nasal polyps were stimulated with ionophore A23187. However, the ionophore stimulated release was greater than that observed for the antigen challenge. When human polyps were stimulated with a mixture of the ionophore and arachidonic acid, all the above products as well as 5-hydroxy-eicosatetraenoic acid (5-HETE), 12-HETE, and 15-HETE were detected in the medium. These data, taken together, demonstrate that human nasal polyps are able to release significant amounts of leukotrienes and histamine upon both immunological and non-immunological stimulations and that these responses might significantly contribute to the symptoms of allergic rhinitis.

Allergens↗
PubMed1986

[Relation between serum markers of hepatitis B virus and alpha fetoprotein in hepatocellular carcinoma in France].

Prevalences of serum markers of hepatitis B virus and alphafetoprotein levels were investigated in 96 patients with hepatocellular carcinoma. Serum HBs Ag was present in 17 patients (17.5 p. 100), anti-HBc antibody alone in 10 patients (10.5 p. 100), and anti-HBs antibody with or without associated anti-HBc antibody in 32 patients (33.5 p. 100). Serum alphafetoprotein levels were increased (greater than 20 ng/ml) in 71 patients (74 p. 100). Serum alphafetoprotein levels were significantly higher in patients with than in patients without serum HBs Ag. Serum alphafetoprotein levels above 1,000 ng/ml were more frequently found in patients with serum HBs Ag or anti-HBc antibody than in other patients. These results suggest the presence of a link between HBs Ag and alphafetoprotein in hepatocellular carcinoma.

Adult↗
PubMed1986

[Alpha-melanotropin in the frog brain: regional distribution, quantification and subcellular distribution].

The distribution of alpha-MSH containing neurons was studied by immunofluorescence in the brain of the frog Rana ridibunda. Most immunoreactive cell bodies were found in the ventral hypothalamic area. A rich network of fluorescent fibers was observed in the ventral infundibular region, coursing towards the preoptic area and the ventral telencephalon. Some fibers, directed backwards, project into median eminence. By means of a specific radioimmunoassay, the concentrations of alpha-MSH immunoreactive material has been determined in 10 different regions of the brain. The highest concentrations were observed in the infundibular and the preoptic regions. Using the immunogold technique, electron microscopy showed that immunostaining was restricted to 70-100 nm dense core vesicles in positive cell bodies and fibers. These results suggest that, in addition to well known hormonal (melanotropic) activity, alpha-MSH could play the role of a neurotransmitter in the frog brain.

Animals↗
PubMed1986

[Localization and identification of neuropeptide Y (NPY) in the brain of an anuran amphibian].

A neuropeptide Y (NPY)-like peptide has been localized in the frog brain by the direct immunofluorescence method. Subcellular localization of NPY has been studied by PAP immunocytochemistry and the immunogold technique. Using a specific radioimmunoassay technique, NPY-like peptide has been quantified in various brain areas and the immunoreactive material was characterized by Sephadex G-50 gel filtration and high performance liquid chromatography. The results indicate that frog NPY is closely related to the porcine molecule and largely distributed in the frog brain. This peptide may play both neurotransmitter and neuroendocrine functions in amphibia.

Animals↗
PubMed1986

[The surgical alternative in the treatment of terminal cardiomyopathies: cardiac transplantation].

Between April 1983 and November 1985, 14 patients have undergone a heart transplant, or 10 men and 4 women, aged from 17 to 55 years. The surgical indication was a cardiomyopathy in terminal evolutive phase, of which the etiology was ischemia in 8 cases, congestion in 5 cases and rheumatism in one case. There was one operative death (7.1%) from acute rejection and a late death secondary to chronic rejection. The actuarial rate of survival at one and 2 years was 81.9%. Post-operative complications, most frequent at an early stage, were arterial hypertension (9 cases), rejection (8 cases) and renal insufficiency (6 cases). During an average post-operative evolution of 13 months, 17 rejection episodes occurred in 10 patients (71.4%) and 5 patients (35.7%) presented with 7 infectious episodes, one of them severe. Cyclosporin's toxicity appeared in the immediate post-operative period by an always reversible increase of the bilirubin and creatinin levels. On a long term, all patients present with arterial hypertension, accompanied by a moderate renal insufficiency (creatinin between 2.2 and 2.4 mg%). Among the survivors, 9 patients (75%) remain completely asymptomatic and have resumed normal physical activities. Cardiac transplantation has therefore become a valid therapeutic alternative, able to greatly improve survival and the functional condition of patients with terminal cardiomyopathy.

Adolescent↗
PubMed1986

[Value of molluscum pendulum in the diagnosis of colorectal neoplastic lesions].

A routine search for skin tags was made before performing colonoscopy in 220 patients, whose mean age was 61.8 years. Sixty-one p. 100 of patients were male. The reasons for colonoscopy were digestive symptoms (95 cases), past history of malignant disease of the colon (MDC) or rectum (67 cases) or other symptoms (58 cases). Eighty-five patients had one or more skin tags, while 78 patients had one or more MDC. MDC in patients with skin tags was more frequent than in patients without skin tags (43.5 p. 100 vs. 30.4 p. 100 respectively, p less than 0.05). However this relationship was age-dependent. No significant relationship was found between the discovery of skin tags and the number of MDC, the carcinomatous nature of the lesion or not, or its degree of dysplasia. In 153 patients without personal history of MDC there was no significant relationship between the existence of skin tags and the discovery of colorectal lesions at colonoscopy. In this series of 220 patients, the sensitivity and specificity of skin tags associated with MDC on colonoscopy was poor (0.47 and 0.66 respectively).

Colonic Neoplasms↗
PubMed1985

Studies on the release of leukotrienes and histamine by human lung parenchymal and bronchial fragments upon immunologic and nonimmunologic stimulation. Effects of nordihydroguaiaretic acid, aspirin, and sodium cromoglycate.

Fragments of human lung parenchyma or bronchi were studied by high performance liquid chromatography, gas chromatography-mass spectrometry, and bioassay for the biosynthesis of 5-lipoxygenase metabolites of arachidonic acid, and by radioenzymatic assay for the release of histamine, upon immunologic and nonimmunologic stimulation. Human lung parenchyma were passively sensitized with serum from timothy-positive allergic patients (radioallergosorbent test, 30-40%) and challenged with 0.5 microgram/ml of timothy allergen. Analysis of the incubation media showed the presence of LTB4, LTC4, LTD4, LTE4, and histamine. Maximum release of LTB4 and LTD4 was observed after 15 min of challenge (92.8 +/- 21, and 67.8 +/- 14 pmol/g tissue wet weight, respectively; mean +/- SEM) whereas maximum release of LTC4 was observed after 5 min of challenge (25 +/- 7.1 pmol). In parallel to leukotriene formation, histamine was released rapidly and reached a maximum after approximately 15 min of challenge (2.85 +/- 0.76 nmol/g tissue). When fragments of human lung parenchyma were stimulated with ionophore A23187 (4 microM), we observed a profile of leukotriene and histamine release similar to that seen in response to the allergen. Ionophore A23187 stimulated the release of two- to fivefold greater amounts of leukotrienes and histamine than did the allergen. Release of LTC4 and histamine was maximal after 5 min of stimulation (83 +/- 22.2 and 5.2 +/- 0.95 nmol/g tissue, respectively), whereas LTB4 and LTD4 release reached a maximum after 15 min (438 +/- 66.6 and 205 +/- 68 nmol/g tissue, respectively). In addition, human lung parenchyma metabolized LTB4 into omega-OH-LTB4 and omega-COOH-LTB4. This tissue also released 5-hydroxy-eicosatetraenoic acid (5-Hete), 12-Hete, and 15-Hete. Fragments of human lung bronchi also released a similar profile of leukotrienes (except LTC4) and histamine when challenged with the allergen or ionophore A23187. Maximum release of LTB4 and LTD4 by allergen or ionophore stimulation was observed after approximately 15 min (40 +/- 7.5 and 21 +/- 8 pmol/g tissue, respectively, upon allergen challenge; 100 +/- 13 and 47 +/- 10.6 pmol/g tissue, respectively, upon ionophore stimulation). The maximum release of histamine by bronchi was observed after approximately 15 min of allergen challenge and 5 min of ionophore stimulation (2.25 +/- 0.65 and 3.15 +/- 0.9 nmol/g tissue, respectively). The release of leukotrienes but not of histamine by human lung parenchyma upon both allergen and ionophore challenge was inhibited by nordihydroguaiaretic acid (NDGA) (ID50, 2 X 10(-6)M).(ABSTRACT TRUNCATED AT 400 WORDS)

Adjuvants, Immunologic↗