Biomedical subjects
Publications and source records attributed to G Pelletier.
Explore the source record for details and available documents.
Using an antiserum to porcine ACTH and the unlabeled antibody preoxidase-antiperoxidase technique, we have found that ACTH is present in neuronal cell bodies located exclusively in the arcuate nucleus of the human hypothalamus. ACTH-containing fibers are distributed extensively throughout the hypothalamus with a greatest density in the periventricular nucleus. No concentration of ACTH fibers could be observed in the neurovascular zone of the pituitary stalk.
The effects of incubation of rat anterior pituitary cells in monolayer culture with 10(-6) M colchicine have been investigated during time-intervals extending from 1 to 96 hours. Prolactin release, as measured by radioimmunoassay, was rapidly inhibited by colchicine, this inhibition being accompanied by increased cellular prolactin content for up to 24 hours of treatment and followed by decreased values of cellular prolactin concentration at later time-intervals. Immunocytochemical localization showed an increased positive reaction for prolactin up to 24 hours after colchicine treatment, whereas transmission electron microscopy demonstrated, in parallel, an increased number of intracellular prolactin secretory granules during the same interval. Longer periods of treatment (24-96 hours) resulted in the appearance of more lysosomes, autophagic vacuoles and microfilaments in the cells, whereas the number of Golgi elements was decreased. Following four hours of colchicine treatment and at later stages, microtubules could no longer be observed in the sections. Scanning electron microscopic data showed that colchicine treatment induced dramatic changes in the cell surface morphology: at short time intervals (4 and 8 hours), the number of microvilli decreased and the cell surface became folded, whereas, later, "bleb"-like protrusions of variable dimensions partially covered the cell surface and seemed to be released from it. These data show a good correlation between secretory activity of prolactin-producing cells and morphological changes induced by colchicine treatment.
This report describes a 70-year-old woman with biventricular failure following an anteroseptal infarction complicated by interventricular septal rupture. Treatment with nitroprusside followed by oral hydralazine eliminated the failure and reduced the shunt from 2.75 to 1 to 1.7 to 1. She is asymptomatic post-discharge. Chronic medical therapy including oral vasodilators may be an acceptable alternative to surgery in a small minority of patients with this complication of myocardial infarction.
To study the biosynthesis and intracellular migration of glycoproteins in the adrenal gland, adult mice were injected intravenously with L-(3H)-fucose and killed from 10 min to 14 days after injection. Semi-thin sections of the adrenal glands were then processed for radioautography. Incorporation of labeled fucose occurred in the steroid-secreting cells of the three zones of the cortex as well as in the adrenalin (A) and noradrenalin (NA) cells of the medulla. At short intervals after injection, the main site of incorporation was the paranuclear region of the cells, suggesting uptake by the Golgi apparatus. Subsequently, labeled glycoproteins migrated from the paranuclear region to other cell sites. The labeling pattern observed in the adrenocortical parenchyme strongly suggests that the glycoproteins are transferred to lysosomes, lipofuscin granules and the cell coat (glycocalyx). Counts of silver grains clearly indicate that these glycoproteins undergo renewal. The qualitative and quantitative analysis of the radioautographs also suggest that glycoproteins, acting as intracellular carriers of steroids, may be released to the extracellular environment together with the hormones. Most of the glycoproteins synthesized by the A and NA cells of the adrenal medulla seem to be transferred to secretion granules in which they may play some role in the cytophysiology of these structures. It is likely that glycoproteins are released from the cells during exocytosis of secretory granules.
Explore the source record for details and available documents.
The localization of enkephalins by immunofluorescence has already shown that these pentapeptides are largely distributed in the central nervous system. In order to clearly identify the structures and organelles containing enkephalins, an immunohistochemical localization of Leu-enkephalin was performed at the ultrastructural level. Leu-enkephalin was detected in dense core vesicles (70--100 nm in diameter) of many nerve fibers in the substantia gelatinosa of the spinal cord, the globus pallidus and the nucleus papabrachialis. These findings support the hypothesis that Leu-enkephalin could act as a neuromodulator.
Using two different specific antisera directed against alpha-melanocyte-stimulating hormone (alpha-MSH), the immunoperoxidase localization of alpha-MSH was performed on sections of the rat brain. With one antiserum, some nerve fibers stained for alpha-MSH were seen close to the apex of ependymal cells near the lumen of the lateral and third ventricles. With the other antiserum, alpha-MSH positive nerve fibers were localized in the pai mater. These results indicate that two different specific antisera directed against a same nolecule can probably recognize different antigenic sites of this molecule. Our findings also suggest a possible source of release for the alpha-MSH present in the cerebrospinal fluid (CSF).
Somatostatin (SRIF), the hypothalmic hormone which inhibits the secretion of growth hormone by the pituitary, has been localized immunohistochemically in the rat hypothalamus after intracerebral injection of colchicine. The number of cell bodies staining for SRIF was increased in the periventricular nucleus while the number of nerve fibers was decreased in the median eminence after treatment. The number of secretory granules containing SRIF in the nerve cell bodies was increased in the treated animals, suggesting a correlation between the number of specific secretory granules and intensity of the immunohistochemical reaction. These observations are in agreement with the hypothesis that SRIF cell bodies in the periventricular nucleus send their axons into the median eminence.
Monolayer cell cultures of embryonic chicken pancreas contain functionally active insulin, glucagon and somatostatin-containing cells as evidenced by immunohistochemical and radioimmunoassay techniques. Hormone release is in relation to the number of each cell type present and responds to known specific secretory stimuli. The relatively high numbers of D-cells and amounts of immunoreactive somatostatin released by this preparation makes this system a suitable model for studies of somatostatin function and secretion.
In an attempt to identify the cells and organellel containing ACTH and beta-lipotropin in the rat brain, an immunocytochemical localization of these two peptides was performed at the electron microscopic level. Both ACTH and beta-lipotropin were localized in dense core vesicles of about 60-80 nm in diameter. Using serial sections, it has been possible to demonstrate that these peptides are contained not only in the same neuronal cell bodies, but also in the same dense core vesicles.
ACTH and some of its fragments have been shown to play a role in a variety of adaptative mechanisms. To clearly identify the nervous structures containing ACTH in the rat brain, an immunohistochemical localization of this peptide was conducted at both light and electron microscopic levels. Nervous fibers staining for ACTH were found to be largely distributed throughout regions of hypothalamus, thalamus, and midbrain. Positive fibers could also be occasionally observed in the spinal cord. Immunostained neuronal cell bodies were only detected in the arcuate nucleus. Essentially, the same results were obtained 2 and 8 weeks after hypophysectomy. In animals pretreated with colchicine, the intensity in the staining of cell bodies was markedly increased, making possible the detection of a larger number of cell bodies. At the electron microscopic level, it was demonstrated that ACTH is contained in dense core vesicles present in nervous fibers and endings. These results indicate that ACTH of nonpituitary origin is synthesized in the central nervous system and could probably be considered as a neurotransmitter of still undefined function.
Gel filtration on Sephadex G-75 of rat gastric mucosal preparation shows two peaks of proteolytic activity. These peaks differ at different ages of animals. The proteolytic activity of the gastric mucosa is spread over a wider range of pH in younger animals than older ones with a shift from higher pH towards lower pH values with increasing age. Hydrocortisone injection to nine day-old rats results in qualitative changes of gastric mucosal proteases, the proteolytic activity pattern of young treated animals being similar to that of untreated adult rat.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.