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Biomedical subjects

J Besson

Publications and source records attributed to J Besson.

At least 55 records · Page 3Linked to original sources
PubMed1984

[Comparative study of 2 assay methods for serum isoniazid in 413 patients: microbiological method and high performance liquid chromatography].

Serum INH was assayed by 2 techniques over 4 years in 413 patients following the administration of a single test dose of 300 mg of isoniazid. The microbiological method measures the inhibitory activity of the serum on the growth of mycobacteria. The pharmacological method consists of high performance liquid chromatography with ultra-violet detection (HPLC). The mean difference in the assays performed by the 2 methods in each subject was 0.061 mcg/ml and the global correlation between the 2 assays was 0.76. Liquid chromatography also allows the simultaneous assay of acetyl INH. Thirty-three per cent of the subjects who received a test dose of 300 mg of INH had a serum INH concentration of between 1 and 2 mcg/ml at the third hour. This study therefore confirms the usefulness of a pre-treatment assay of INH and the good correlation of the results obtained with the 2 methods.

Adult↗
PubMed1983

Release of vasoactive intestinal peptide from rat jejuno-ileum in vitro. Effect of various depolarizing agents.

Vasoactive intestinal peptide (VIP) can be released in vitro from intestinal slices under veratridine and batrachotoxin depolarization, whereas potassium depolarization has no effect. The lack of an effect of potassium observed in this peripheral preparation is different from the positive action described for it in the CNS. The present data suggest that VIP can be released through different mechanisms in the peripheral and central nervous system.

Animals↗
PubMed1983

Vasoactive intestinal polypeptide: presence in neuroblastoma X glioma hybrid cells.

Extracts of neuroblastoma X glioma hybrid cells 108CC15 and their parental lines were investigated for the presence of vasoactive intestinal polypeptide (VIP). With the aid of a radioimmunoassay and a receptor binding assay, VIP activity was found in the hybrid cells, to a lesser extent in neuroblastoma cells, but not in glioma cells. These results suggest a neuronal function of VIP. Since the hybrid cells also contain acetylcholine and opioids, they may be useful in studies of co-release of neurohormones.

Animals↗
PubMed1983

[The genetic code and cyclic codes].

The genetic code can be considered as degenerated from a minimal cyclic code, whose maximal chain is given. We study the relation of this code with the cyclic code corresponding to the 64 triplets. Finally we compare the minimal code to that obtained from a binary cyclic code.

Adenine↗
PubMed1982

Release of vasoactive intestinal peptide from rat brain slices by various depolarizing agents.

The release of vasoactive intestinal peptide (VIP) from rat brain cortical and amygdala slices was studied by using various depolarizing agents such as potassium (K+), veratridine (VER) and batrachotoxin (BTX). The basal release of VIP observed is of the same order of magnitude for both structures and represents less than 0.1% of the tissue content per minute measured by a specific radioimmunoassay. Maximal stimulation obtained with 56 mMK+, 50 microM VER and 1 microM BTX corresponds to a mean 3-fold increase above the basal release of VIP in both cortex and amygdala. When the incubation medium did not contain any calcium, the action of potassium on the release of VIP was suppressed. When tetrodotoxin (1 microM) was added to the incubation medium, the veratridine- and batrachotoxin-induced release of VIP was inhibited whereas K+-induced release was unaffected. These results support the hypothesis that VIP can be a neurotransmitter in the central nervous system.

Amygdala↗
PubMed1982

A new neuroregulator: the vasoactive intestinal peptide or VIP.

VIP is a neuroregulator occurring in the central and peripheral nervous system which exhibits the function of neurotransmitter in the brain, neuroendocrine substance at the pituitary level, and neuroparacrine substance in peripheral organs. The structure and the specificity of the molecule as studied by antibody and receptor, and its location in brain and peripheral organs are summarized as well as its numerous biological effects. The method used to demonstrate the involvement of VIP in a physiological regulation is described and illustrated by two examples: the effect of VIP on gut epithelium and the neuroendocrine action of VIP in inducing prolactin release from pituitary cells. The consequence of this recent progress in the knowledge of VIP release and action in human physiology and disease is indicated.

Adenylyl Cyclases↗
PubMed1982

Ultrastructural evidence for endogenous vasoactive intestinal peptide-like immunoreactivity in the pituitary gland.

The immunocytological method was used to investigate whether vasoactive intestinal peptide (VIP) is present in the pituitary gland and to localize the peptide at the cellular and subcellular levels. Pituitaries of Wistar male and female rats (Iffa Credo) were fixed in glutaraldehyde 2.5% and postosmicated and frozen in liquid nitrogen. Ultrathin slices, obtained by cryo-ultramicrotomy were incubated with the antiserum. The antigen-antibody reaction was detected by peroxidase-antiperoxidase complexes revealed by 4-chloro-1-naphtol. The prolactin (PRL)-secreting cells were identified by using an anti-oPRL antiserum. The PRL immunoreactivity was localized in secretory granules of irregular shapes. An anti-VIP serum was used which neither cross-reacted with the several fragments of VIP molecule nor with peptides from gut or hypothalamus. The VIP immunoreactivity obtained with this antiserum, was observed in PRL cells only but never in so-matotropic, gonadotropic, corticotropic and thyrotropic cells. The immunoreactivity was localized in the cytoplasmic matrix between and around the secretory granules but not in the organelles, and in the nucleus distributed all over the euchromatin near to the heterochromatin regions. No reaction was observed by using either nonimmune serum or anti-VIP antiserum incubated with VIP. No modification of VIP immunoreactivity was observed by using anti-VIP antiserum incubated with somatostatin, gonado- or thyroliberin. These data (1) provide immunocytological evidence for presence of VIP in pituitary gland; (2) indicate the presence of this peptide in one particular pituitary cell type, and (3) support the hypothesis that VIP could have a direct effect on the control of PRL secretion.

Animals↗
PubMed1981

Gonadotrophin release by gonadotrophs incubated with gonadotrophin-releasing hormone is independent of intracellular cAMP accumulation.

Rat pituitary cells were dispersed with trypsin and separated by sedimentation at unit gravity. The distributions of prolactin (Prl), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were determined, and two enriched cell populations (mammotrophs and gonadotrophs) were subsequently cultured. During a 4 h incubation, gonadotrophin-releasing hormone (GnRH) stimulated the release of LH and of FSH by both the unfractionated population and the enriched gonadotrophs; the magnitude of this stimulation increased with the length of the pre-culture periods, and the amount of LH released into the medium correlated strongly with the amount of FSH, whatever the length of the pre-culture period. The cellular cAMP content was also enhanced during the 4 h incubation, but no correlation was found between the hormone release and the cAMP accumulation. Furthermore, during the first 30 min of incubation with GnRH there was no increase of cellular cAMP, whatever cell population used. We conclude that the gonadotrophin release was independent of the cAMP accumulation observed in pituitary cells several hours after stimulation by GnRH; consequently, the late increase in the nucleotide is suggested to be a non-specific secondary process.

Animals↗
PubMed1980

[Dexamethasone regulation of the prolactin release induced by vasoactive intestinal peptide (VIP)].

The regulation of prolactin (PRL) secretion induced by the vasoactive intestinal peptide (VIP) has been studied on purified male Rat Pituitary PRL cells obtained by means of velocity sedimentation at unit gravity. Dexamethasone (10(-9) M) in the incubation medium inhibits the stimulatory effect of VIP (10(-7) M) on PRL release. This result suggests that glucocorticoids play an important role in the regulation of VIP effects at the effects at the pituitary level.

Animals↗
PubMed1980

Effect of vasoactive intestinal peptide (VIP) on the release of adenohypophyseal hormones from purified cells obtained by unit gravity sedimentation. Inhibition by dexamethasone of vip-induced prolactin release.

The effect of vasoactive intestinal peptide (VIP) on the release of prolactin (PRL), gonadotropins (LH and FSH), growth hormone (GH) and corticotropin (ACTH) was studied using purified rat anterior pituitary cells obtained by means of velocity sedimentation at unit gravity. VIP, at concentrations ranging from 10(-10) to 10(-7) M, stimulated PRL secretion in a dose-dependent manner with an ED50 of 2 nM and a maximal response of 530% of control values. In contrast, similar concentrations of VIP did not affect the release of either LH, FSH, GH or ACTH from the corresponding enriched cell populations. Addition of dexamethasone (10(-9) M) to both preincubation and incubation medium of PRL cells completely inhibited VIP-induced PRL release. The present results further support the hypothesis that VIP is of physiological importance in the control of PRL secretion and demonstrate that corticosteroids can modify the responsiveness of PRL cells to VIP.

Animals↗
PubMed1980

Effect of steroids on vasoactive intestinal peptide in discrete brain regions and peripheral tissues.

The effect of castration and adrenalectomy was studied on vasoactive intestinal peptide (VIP) concentrations in various brain and peripheral structures of male rats. Castration has no effect on any of the structures studied, whereas 4 weeks adrenalectomy (ADX) decreases VIP concentrations in the hippocampus and increases them in the adenohypophysis, two structures known to contain large amounts of glucocorticoid receptors. Corticosterone administration restores VIP levels to control values only in the dorsal hippocampus. In contrast, dexamethasone counteracts both the decrease and the increase of VIP concentrations obtained after ADX in the hippocampus and in the adenohypophysis respectively. The present results suggest that corticosteroids can be involved in the regulation of VIP actions both in the brain and in the adenohypophysis.

Adrenalectomy↗
PubMed1979

Vasoactive intestinal peptide inhibits release of somatostatin from hypothalamus in vitro.

The effect of vasoactive intestinal peptide (VIP) was studied on the release of somatostatin (SRIF) from slices of several regions of the rat brain in vitro. VIP induced a dose-dependent inhibition of SRIF release from mediobasal hypothalamic slices but did not interfere with SRIF release from preoptic area, amygdala or cortex. VIP inhibition had an apparent affinity: Kd = 6.8 +/- 3.9 x 10(-11) M. Secretin had a similar effect but at 600-fold higher concentrations (Kd secretin = 4.2 +/- 0.6 x 10(-8) M). Gucagon was ineffective in concentrations ranging from 10(-10) M to 10(-7) M. The data are consistent with a role of VIP in the hypothalamic control of growth hormone secretion.

Animals↗
PubMed1979

[Vasoactive intestinal peptide (VIP): specific receptors and adenylate cyclase activation in a human prolactin-secreting pituitary tumor].

Receptors for the Vasoactive Intestinal Peptide (VIP) were characterized in particles enriched in plasma membranes obtained from a human prolactin-secreting pituiatry tumor. Native VIP inhibited competitively the binding of 125I-VIP to the particles and stimulated cyclic AMP production; both these effects were observed at concentrations of VIP as low as 10(-11)-10(-10) M, which are compatible with VIP concentrations in the hypothalamopituitary portal blood.

Adenylyl Cyclases↗