Search PubMed⌕ Search

Biomedical subjects

R Pochet

Publications and source records attributed to R Pochet.

At least 73 records · Page 4Linked to original sources
PubMed1986

Vitamin D-dependent calcium binding protein immunoreactivity in human retina.

Using immunohistochemistry, vitamin D-dependent calcium binding protein (D-CaBP) has been detected in human retina. In the photoreceptor layer the cones are positive but the rods are negative. In the inner nuclear layer, horizontal cells and some bipolar cells are D-CaBP. In the ganglion cell layer both small and large somata are immunoreactive for D-CaBP. Beaded fibres from the outer plexiform, inner plexiform and fibre layers are also positive.

Cells↗
PubMed1986

Calcium movements in aortae from arthritic rats.

40Ca content, 45Ca uptake, influx and efflux were measured in aortae from arthritic rats. 40Ca content measured by atomic absorption spectrometry was higher in aortae from arthritic than from normal controls. 45Ca uptake, inflow and outflow were also enhanced in aortae from arthritic rats whether under basal or stimulated conditions (e.g. in the presence of high potassium or noradrenaline). Verapamil failed to inhibit basal 45Ca uptake but normally inhibited 45Ca inflow stimulated by high potassium or noradrenaline in both aortic preparations. No histological difference was detected by optical microscopy between normal and arthritic aortae. It is concluded that aortae from adjuvant arthritic rats are apparently characterized by a higher intracellular Ca++ content resulting from enhanced Ca++ inflow through at least three Ca++ pathways. This higher intracellular content may explain why aortae from arthritic rats are less dependent on extracellular Ca++ than aortae from normal rats when stimulated by agonists like serotonin and noradrenaline.

Animals↗
PubMed1985

Rat brain synthesizes two 'vitamin D-dependent' calcium-binding proteins.

Two proteins from rat brain reacting against anti-chick intestinal vitamin D-dependent calcium-binding protein were characterized in terms of their mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and their molecular size. The proteins were present in the isolated cytoplasm and were produced following translation of brain mRNA in the rabbit reticulocyte lysate system. Their apparent molecular weight was 29,000 and 27,000 daltons whereas rat kidney contained only one protein cross-reacting with this antiserum and with a molecular weight of 27,000 daltons.

Animals↗
PubMed1983

A 45 000 molecular weight human renin precursor is synthesized in a cell-free translation system.

Human kidney mRNA species were isolated and fractionated through a continuous sucrose gradient ultracentrifugation. mRNA fractions were translated by using a rabbit reticulocyte lysate and [35S]methionine as tracer. Double immunoprecipitation was carried out with highly specific anti-human renin and anti-rabbit gamma-globulin antisera. A 15S mRNA has been found to direct synthesis of a 45 000 molecular weight protein immunoprecipitable with anti-human renin. This protein is considered to be the ultimate precursor of renin (pre-prorenin).

Enzyme Precursors↗
PubMed1983

Pituitary-dependent renin-like immunoreactivity in the rat testis.

By means of a specific anti-rat renin antiserum, immunohistochemical staining was observed restricted to Leydig cells of rat testis. Specificity of the staining was ascertained by the absence of reaction with nonimmune serum or with the antiserum preincubated with rat renin. Specific staining of Leydig cells was absent in newborn rats; it developed with the onset of puberty. Staining was suppressed or abolished by hypophysectomy and estrogen treatment and was reduced by gonadotropin stimulation. Vasectomy destroyed the seminiferous epithelium but did not impair renin-like immunoreactivity of the interstitial tissue. It is concluded that Leydig cells contain a pituitary-dependent renin-like substance.

Age Factors↗
PubMed1983

The human heart beta-adrenergic receptors. II. Coupling of beta 2-adrenergic receptors with the adenylate cyclase system.

The beta-adrenergic stimulation of adenylate cyclase in membranes from human auricles, ventricles, and fetal heart was compared with the binding properties of beta-adrenergic receptors in human auricles. In terms of adenylate cyclase activation, three full agonists (isoproterenol, epinephrine, and norepinephrine), four partial agonists (procaterol, salbutamol, fenoterol, and zinterol), and four antagonists (propranolol, metoprolol, atenolol, and practolol) were tested. The beta-adrenergic activation of adenylate cyclase in membranes from rat heart (with a majority of beta 1-adrenergic receptors), rat erythrocytes, and rat reticulocytes (with a homogeneous population of beta 2-adrenergic receptors) served as reference. The reactivity of human heart adenylate cyclase, estimated by the Kact or Ki values of 11 beta-adrenergic agents, indicated that the activation of this enzyme occurred through receptors of the beta 2-subtype only. Receptors of the beta 1-subtype (50% of the total population) were not coupled to the enzyme.

Adenylyl Cyclases↗
PubMed1981

Radioautographic localization of prolactin messenger RNA on histological sections by in situ hybridization.

In situ hybridization of complementary [H3]DNA ([H3]cDNA) synthetized from purified rat prolactin messenger RNA (rPRL mRNA) was performed to specifically identify on histologic sections of rat hypophysis cells expressing the PRL gene. Radioautographic labelling occurred over weakly acidophilic cells, while other acidophils, with darker cytoplasm did not contain more silver grains than blood vessels.

Animals↗
PubMed1980

Induction and properties of beta-adrenergic receptors during erythroid differentiation of Friend leukemic cells.

beta-Adrenergic receptors on Friend erythroleukemic cells were identified by the use of 125I-labeled hydroxybenzylpindolol, a potent beta-adrenergic antagonist. Binding of this ligand was saturable and stereospecific. The relative orders of potency of isoproterenol, epinephrine, and norepinephrine to displace bound hydroxybenzylpindolol indicate that the Friend cells have beta 2-adrenergic receptors. After culture for 6 days in the presence of dimethyl sulfoxide or hexamethylene bisacetamide, both undifferentiated and differentiated cells have a similar number of receptors (1500 per cell), but the density of beta receptors on the cell surface increases during the process of erythroid differentiation. Incubation of the Friend cells for 24 hr with high concentrations of butyric acid, dimethyl sulfoxide, or hexamethylenebisacetamide resulted in a striking increase of th number of beta-catecholamine receptors. The induction of beta-adrenergic receptors also occurred in the presence of the tumor promoter 12-O-tetradecanoylphorbol 13-acetate and dexamethasone.

Acetamides↗
PubMed1979

Dissociation by cooling of hormone and cholera toxin activation of adenylate cyclase in intact cells.

Cholera toxin, through adenylate cyclase activation reproduced cyclic AMP-mediated effects of thyroid-stimulating hormone (TSH) in dog thyroid slices, i.e. protein iodination, [1-14C]glucose-oxidation and hormone secretion. Iodide and carbamylcholine decreased the cyclic AMP accumulation induced by cholera toxin as well as by TSH, which supports the hypothesis of an action of these agents beyond the steps of hormone-receptor and receptor-adenylate cyclase interaction. Cooling to 20 degrees C did not impair the TSH induced cyclic AMP accumulation in thyroid slices, but completely suppressed the cholera toxin effect. This observation has been extended to other hormones and target tissues, such as the parathyroid hormone (PTH) (kidney cortex), adrenocorticotropic hormone (ACTH) (adrenal cortex) and luteinizing hormone (LH) (ovary systems). As in thyroid, cooling dissociated the cholera toxin and hormonal effects on cyclic AMP accumulation. In homogenate, cooling decreased cyclic AMP generation in the presence of cholera toxin but at 20 degrees C and 16 degrees C a cholera toxin stimulation was still observed. These results bear strongly against the hypothesis that the glycoprotein hormones TSH and LH acetivate adenylate cyclase by a mechanism identical to cholera toxin.

Adenylyl Cyclases↗
PubMed1979

Distribution of beta-adrenergic receptors on human lymphocyte subpopulations.

A technique is described allowing the quantification and the characterization of specific beta-adrenergic receptors in intact living human lymphocytes. 125I-Iodohydroxybenzylpindolol, a potent beta-adrenergic antagonist was used to label specific binding sites on unfractionated lymphoid cells and on purified subpopulations of T (F1 and F2) and B cells. F1 and F2 were obtained by filtration through nylon wool column as previously described (Delespesse et al., 1976), they differ in their response to mitogens, and in their interactions with adherent cells and B cells. 125I-HYP binding to unfractionated lymphocytes was a saturable, stereospecific and rapid process with a dissociation constant of 2.5 10(-10) M and a binding capacity of 400--600 sites/cell. Bindings on unfractionated lymphocytes, purified B cells and T cells of the F2 fraction were similar. No detectable binding was noted on T cells from the F1 fraction. Enriched T cells obtained by a rosetting technique displayed 200 receptors/cell.

Adrenergic beta-Agonists↗
PubMed1976

Kinetics of adenosine 3':5'-monophosphate accumulation in dog thyroid slices.

Dog thyroid slices have been stimulated in vitro by thyrotropin. The kinetics of adenosine 3':5'-monophosphate (cyclic AMP) accumulation due to the activation of adenylate cyclase were measured. Experimental results have been interpreted by means of a numerical simulation based on a theoretical description of the overall process which consists of three steps: (a) the penetration of thyrotropin in the slices, (b) the binding of the hormone to the specific receptor and the consequent activation of adenylate cyclase, (c) the kinetics of cyclic AMP accumulation in each cell due to the interplay between synthesis and degradation. The numerical values of the parameters needed for the simulation were deduced from separate experiments. Diffusion of thyrotropin in the slices has been calculated from the kinetics of efflux of [3H]sucrose, and with or without albumin. Adenylate cyclase activity and activation by thyrotropin in homogenates and purified membranes were measured. Binding experiments of cyclic AMP on crude extract of dog thyroid lead to the conclusion that the maximal capacity of the specific binding site is close to the cyclic AMP content in resting thyroid cells. The purpose of this paper is to verify the validity of the current concepts about the mechanisms taking place in this process by comparing experimental results and theoretical simulation. It results from the study that for this system the time between the activation of adenylate cyclase and half maximal cyclic AMPaccumulation is equal to 3 min 45 s and the pool of cyclic AMP is renewed three times per minute. It has been also stressed that the thickness of the slices as well as inhibitors of phosphodiesterases change the apparent kinetics of cyclic AMP accumulation.

Adenylyl Cyclases↗