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M Parmentier

Publications and source records attributed to M Parmentier.

At least 181 records · Page 10Linked to original sources
PubMed1988

Localization and secretion of newly synthesized and stored renin: two compartments and secretory mechanisms.

Intracellular pathways of renin secretion were examined by use of rat renal cortical slices. Renin was labeled with [35S]methionine by incubating the cortical slices for 2 h. The labeled immunoprecipitable renin was found in microsomal fraction (F1) but not in the renin granule fraction (F2). The newly synthesized and radiolabeled renin was secreted from the incubated slices into the medium. The rate of secretion of the labeled renin activity was not increased by 10(-6) M isoproterenol, whereas secretion of total renin activity was markedly stimulated. The isoelectric focusing patterns of renin in F1 and F2 were compared with those secreted with or without isoproterenol. The pattern of F1 was similar to that secreted in the medium without stimulation. These studies suggest that a constitutive pathway exists for renin secretion from the kidney and that the constitutive (nonstimulable) pathway is responsible for the secretion of newly synthesized renin and that it is not stimulated by a beta-adrenergic mechanism.

Animals↗
PubMed1987

Human 27-kDa calbindin complementary DNA sequence. Evolutionary and functional implications.

Human 27-kDa calbindin cDNA clones were selected by antibody screening from lambda gt11 brain libraries. The sequence revealed an open reading frame coding for a protein of 261 amino acids, containing four active calcium-binding domains, and two modified domains that had presumably lost their calcium-binding capability. Comparison with chick and bovine calbindins showed that the protein was highly conserved in evolution (evolutionary rate: 0.3 x 10(-9) amino acid-1 year-1) and that active and inactive domains were equally conserved. From the data we postulate that calbindin has an important physiological function involving protein--protein interactions. Comparison of calcium-binding domains from various proteins suggested that all members of the troponin C superfamily derive from a common two-domained ancestor, but that duplications leading to calbindin and to the four-domained calcium-binding proteins took place independently on different branches of the evolutionary tree. Preliminary data showed that another calcium-binding protein, homologous to calbindin, is present in the brain and encoded by a different gene.

Amino Acid Sequence↗
PubMed1987

Calbindin in vertebrate classes: immunohistochemical localization and Western blot analysis.

Calbindin immunoreactivity was investigated in various vertebrates. Positive labeling was observed in the absorptive cells of the duodenum of all birds and reptiles but not in mammals, amphibia, or fish. Staining was present in the kidney distal convoluted tubule from amphibia and higher vertebrates. Fish kidney was negative. In the central nervous system of all species investigated, cellular bodies and fibers were Calbindin positive. Their distribution was quite broad and correlates well with the previously reported mapping for chick and rat. Western blot analysis revealed two Calbindins in brain from mammals, birds, reptiles, and amphibia (27,000 and 29,000 Da). Only one band was detected in fish. We conclude that Calbindin from the evolutionary point of view is primarily a neuronal protein, with a highly conservative character.

Amphibians↗
PubMed1987

Calcium binding protein immunoreactivity in pigeon retina.

Pigeon retina has been mapped immunocytochemically for vitamin D-dependent calcium-binding protein (D-CaBP). Immunoreactivity was found in the cones of the yellow field, but not in photoreceptors of the red field. The D-CaBP-containing cones were a subpopulation of those in the yellow field having straight fibres leading to their synaptic terminals. D-CaBP immunoreactivity was also found in horizontal cells, the amount present varying according to position along the retina, and in some amacrine cells. Immunoblots of pigeon retinal proteins separated by SDS-polyacrylamide gel electrophoresis indicated two D-CaBP forms, having apparent molecular weights of 27000 and 29000. Both these forms of D-CaBP have been found previously in rat and pigeon brain.

Animals↗
PubMed1986

Ultrastructural localization of brain 'vitamin D-dependent' calcium binding proteins.

Rat brain vitamin D-dependent calcium-binding protein (D-CaBP) was assessed for vitamin D dependency, calcium binding and ultrastructural localization within neurons. No evidence of vitamin D dependency could be derived from the experiments on vitamin D-deficient rats. A 95% pure extract of the 27-kDa brain D-CaBP was shown to bind 45Ca on nitrocellulose membrane after sodium dodecyl sulphate-electrophoresis, specifically on the 27-kDa CaBP band. Immunogold staining with electron microscopy allowed detection of D-CaBP into Purkinje cells and climbing fibers of the cerebellum. The immunoreactivity was found to be hyaloplasmic and never membrane-bound. It was present in neuronal soma, neurites and postsynaptic as well as presynaptic terminals. These findings rule out D-CaBP as a possible neurotransmitter and bring further support to the hypothesis that the protein functions as a cytosolic calcium buffer. Immunohistochemical detection of D-CaBP is proposed as a means for morphologic detection of neurons with high calcium metabolism.

Animals↗
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

The storage form of renin in renin granules from rat kidney cortex.

Renin granules were partially purified from rat kidney cortex, and a storage form of renin in the granules was examined. Renin granules were isolated by discontinuous Percoll density gradient centrifugation followed by continuous Percoll density gradient centrifugation. The partially purified fraction was free from mitochondria and microsomes, as judged by the absence of marker enzymes of these organelles, but contained some lysosomal enzyme activities. The specific renin activity was 0.58 mg angiotensin I/hr/mg protein, 500 times as active as the original homogenate. Immunochemical staining with specific antisera against rat kidney renin revealed that about 10% of the granules recovered in the partially purified fractions were stained strongly. The stored renin was not activated either by acidification or by trypsin treatment, indicating that stored renin was in the fully active form. By sodium dodecyl sulfate gel electrophoresis, the stored renin had two different molecular weights, 38,000 and 36,000, and these molecular weights were not reduced by dithiothreitol or 2-mercaptoethanol, suggesting that these renins are single-chain types as opposed to the two-chain type found in male mouse submaxillary gland. These results suggest that active renins with two different molecular weights may be released from renin granules of juxtaglomerular cells.

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↗
PubMed1985

Biochemical studies of rat atrial natriuretic factor.

The natriuretic substances were purified from rat atrium (ANF, atrial natriuretic factor) and were shown to be identical with the inhibitor of norepinephrine-induced contraction of smooth muscle. Their four native forms were isolated. Amino acid sequence analyses showed they are peptides with 35, 31, 30 and 25 amino acid residues respectively and contain a ring structure consisting of 17 amino acid residues and a disulfide bridge. The presence of a high molecular weight prohormone was shown. cDNA coding for the precursor was cloned and used to deduce the amino acid sequence of the preprohormone. Genomic DNA for ANF was cloned and the presence of two introns were found. Several ANF peptides were synthesized. Structure-function studies showed that the ring structure is essential for the activity. Antibodies produced against the synthetic 25 amino acid residue ANF were used to develop radioimmunoassay. The presence of ANF in rat plasma was demonstrated as evidence that ANF is a circulating hormone. ANF was also found in the hypothalamus of rats. The quantitative determination of the synthetic ability of ANF has been determined by the application of ANF cDNA for the quantification of ANF messenger RNA. Immunohistochemical methods localized ANF in cardiac atriocytes, gonadotrophs in anterior pituitary and adrenal medulla (chromaffin cells). A strong immuno-reactivity was found in dark cells of the collecting ducts of the kidney. ANF increases cyclic GMP in target cells suggesting that cyclic GMP may be the intracellular mediator of ANF action.

Adrenal Cortex↗
PubMed1984

Cloning of genomic DNA for human atrial natriuretic factor.

A human genomic DNA clone for atrial natriuretic factor (ANF) gene was isolated from a human gene library using the previously cloned cDNA for rat ANF as a probe. Partial nucleotide sequencing of the cloned DNA revealed the location of a 120-bp long intron between Lys-41 and Asn-42 of the ANF precursor. Restriction mapping also suggested the existence of at least one other intron in or proximal to the 3' -untranslated region.

Amino Acid Sequence↗
PubMed1984

Demonstration of renin activity in purified rat Leydig cells: evidence for the existence of an endogenous inactive (latent) form of enzyme.

Previous histochemical studies demonstrated the specific localization of immunoreactive renin-like substance in Leydig cells of rat testes. The studies reported herein demonstrate a specific renin enzyme activity in the two purified populations of Leydig cells (I and II) of mature rat testes. Leydig cells of both populations also exhibited an inactive (latent) renin which was activated by the sulfhydryl reagents dithiothreitol, beta-mercaptoethanol, glutathione, and cysteine but not by limited proteolysis by trypsin, which is a characteristic activating agent for prorenin or inactive renin of the zymogen type. The activation of latent renin by dithiothreitol produced approximately 5-and 10-fold increases in renin activity in Leydig cell populations I and II, respectively. Active and latent renin showed strong affinity to an antirat renin immunoglobulin-Sepharose column, indicating a close immunological relationship of latent renin to active renin. Both active and latent renin from Leydig cell populations (I and II) exhibited the pH optimum of 6.0. The gel filtration of Leydig cell extracts characteristically revealed that the apparent mol wts of active and latent renin were 39,000 and 48,000, respectively. Both active and latent renin in Leydig cells remained almost at similar levels through four continuous subcultures. The activity of latent renin slightly increased during the four consecutive subcultures, while active renin levels remained almost constant.

Animals↗
PubMed1983

Vitamin D metabolism in nephrotic rats.

Vitamin D metabolites were measured in sera of normal, vitamin D deficient and nonazotemic nephrotic rats. The concentrations of all metabolites were reduced in nephrotic and vitamin D deficient animals although 1,25-dihydroxyvitamin D values remained relatively normal in the nephrotic group. Twenty-four hours after the intravenous injection of tritiated 25-hydroxycholecalciferol, approximately 34% of the injected radioactivity appeared in the urine of the nephrotic animals compared with 0.4% in the controls. In extracts from nephrotic sera subjected to high performance liquid chromatography, the percentage of radioactive counts comigrating with 1,25-dihydroxycholecalciferol and 24,25-dihydroxycholecalciferol was significantly increased. The various metabolites were present in urine in approximately the same ratios as in serum. Dynamic histomorphometry of tibial metaphyses showed no abnormality. Urinary losses of vitamin D metabolites constitute the major cause for low serum values in nephrotic rats. The apparent synthetic rates are not impaired.

24,25-Dihydroxyvitamin D 3↗
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↗
PubMed1979

Compared localizations of prolactin-like and adrenocorticotropin immunoreactivities within the brain of the rat.

By an immunoperoxidase (PAP) technique, ACTH- and prolactin-like substances were detected in neurons of several hypothalamic nuclei in young and adult rats. Neurons in the arcuate and ventromedial nuclei were simultaneously both ACTH-like and PRL-like positive. Labelled fibres were followed to their fields of projections. Intensity of labelling was not influenced by experimental procedures known to change PRL and ACTH content of the pituitary. Colchicine enhanced labelling of perikarya while lowering that of fibres. The results support neuronal synthesis of hormonal ACTH and PRL related molecules and their involvement in the control of autonomic nerve functions.

Adrenocorticotropic Hormone↗
PubMed1979

Cellular localization of a prolactin-like antigen in the rat brain.

The distribution of immunoreactive neurones and fibres was studied in rat brain using an antiserum to rat prolactin. Neurones containing the immunoreactive material were localized in the arcuate, ventromedial, premamillary, supraoptic and paraventricular nuclei of the hypothalamus. Immunoreactive nerve fibres were widely distributed within the brain. No differences were observed in labelling between male and female rats, or as a consequence of hypophysectomy.

Animals↗
PubMed1979

[Cutaneous and subcutaneous blood flow measurement in rabbit's ear by epicutaneous diffusion of xenon 133. Influence of the arteriovenous anastomosis].

The cutaneous and subcutaneous blood flow measurement by a diffusible inert gas concerns theorically capillary nutritional flow. In clinical routine, where pathological openning of arteriovenous anastomosis is suspected, the blood flows measured by Xenon technic are often increased. The function of the shunts are displayed on the epuration curve obtained on a region where there are numerous: rabbit's ear.

Animals↗