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E Mezey

Publications and source records attributed to E Mezey.

At least 91 records · Page 5Linked to original sources
PubMed1995

Regulation of rat alcohol dehydrogenase by cyclic AMP in primary hepatocyte culture.

Alcohol dehydrogenase (ADH) is enhanced separately by epinephrine and by glucagon in primary rat hepatocyte culture. This study determined whether cyclic AMP, a common mediator for some of the actions of the above hormones, increases ADH. Administration of theophylline, a cyclic AMP phosphodiesterase inhibitor which increases endogenous cyclic AMP, in a dose of 100 mg/kg to rats for 5 days, increased ADH activity. Dibutyryl cyclic AMP (10 microM) added to primary hepatocytes in culture increased ADH mRNA and ADH activity at 12 and 24 h, respectively, after its addition. The increase in ADH mRNA was preceded by an increase in the expression of C/EBP beta mRNA and in C/EBP beta protein. Dibutyryl cyclic AMP, in transient transfection experiments of primary rat hepatocyte culture, activated an ADH promoter gene construct containing the C/EBP binding site, but failed to activate a construct containing a 4-bp mutation at this site. These results show that cyclic AMP induces ADH and suggests that this effect is mediated by C/EBP beta binding to the C/EBP site. The previously demonstrated induction of ADH by epinephrine and glucagon may be mediated by a common pathway via an increase in cyclic AMP.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

Extrapituitary expression of the rat V1b vasopressin receptor gene.

[Arg8]vasopressin (AVP) stimulates adrenocorticotropic hormone release from the anterior pituitary by acting on the V1b AVP receptor. This receptor can be distinguished from the vascular/hepatic V1a and renal V2 AVP receptors by its differential binding affinities for structural analogous of AVP. Recent studies have shown that the cloned V1a and V2 receptors are structurally related. We have isolated a clone encoding the V1b receptor from a rat pituitary cDNA library using polymerase chain reaction (PCR)-based methodology. The rat V1b receptor is a protein of 421 amino acids that has 37-50% identity with the V1a and V2 receptors. Homology is particularly high in the seven putative membrane-spanning domains of these guanine nucleotide-binding protein-coupled receptors. Expression of the recombinant receptor in mammalian cells shows the same binding specificity for AVP agonists and antagonists as the rat pituitary V1b receptor. AVP-stimulated phosphotidylinositol hydrolysis and intracellular Ca2+ mobilization in Chinese hamster ovary or COS-7 cells expressing the cloned receptor suggest second messenger signaling through phospholipase C. RNA blot analysis, reverse transcription PCR, and in situ hybridization studies reveal that V1b receptor mRNA is expressed in the majority of pituitary corticotropes as well as in multiple brain regions and a number of peripheral tissues, including kidney, thymus, heart, lung, spleen, uterus, and breast. Thus, the V1b receptor must mediate some of the diverse biological effects of AVP in the pituitary as well as other organs.

Amino Acid Sequence↗
PubMed1995

Molecular neurobiology and pharmacology of the vasopressin/oxytocin receptor family.

1. VP and OT mediate their wealth of effects via 4 receptor subtypes V1a, V1b, V2, and OT receptors. 2. We here review recent insights in the pharmacological properties, structure activity relationships, species differences in ligand specificity, expression patterns, and signal transduction of VP/OT receptor. 3. Furthermore, the existence of additional VP/OT receptor subtypes is discussed.

Amino Acid Sequence↗
PubMed1995

Analysis of aldehyde oxidase and xanthine dehydrogenase/oxidase as possible candidate genes for autosomal recessive familial amyotrophic lateral sclerosis.

Recently, point mutations in superoxide dismutase 1 (SOD1) have been shown to lead to a subset of autosomal dominantly inherited familial amyotrophic lateral sclerosis (ALS). These findings have led to the hypothesis that defects in oxygen radical metabolism may be involved in the pathogenesis of ALS. Therefore, we decided to analyze other enzymes involved in oxygen radical metabolism for possible involvement in other forms of ALS. We report here analysis of two genes encoding the molybdenum hydroxylases aldehyde oxidase (AO) and xanthine dehydrogenase/oxidase (XDH) for involvement in ALS. Of particular interest, one gene identified as encoding aldehyde oxidase is shown to map to 2q33, a region recently shown to contain a gene responsible for a familial form of ALS with autosomal recessive inheritance (FALS-AR). The AO gene appears to be located within 280,000 bp of simple sequence repeat marker D2S116, which shows no recombination with the FALS-AR locus. The AO gene is highly expressed in glial cells of human spinal cord. In addition, we mapped a gene for XDH to 2p22, a region previously shown to contain a highly homologous but different form of XDH. Neither of these XDH genes appears to be highly expressed in human spinal cord. This evidence suggests that AO may be a candidate gene for FALS-AR.

Aldehyde Oxidase↗
PubMed1995

PACAP acts through VIP type 2 receptors in the rat testis.

Pituitary adenylate cyclase-activating peptide (PACAP) is present and synthesized in the testis in large amounts. Messenger RNA encoding the peptide is expressed in a stage specific manner in the developing germ cells. PACAP regulates a variety of physiological actions, among them, paracrine modulation of spermatogenesis. The PACAP peptides are potential ligands of at least three receptor types, the type I PACAP receptor, VIP1 and VIP2 receptors. Although PACAP27 binding sites have found in the testis, the receptor at which it acts has not been identified. We used in situ hybridization with riboprobes to identify the PACAP binding receptor present in the testis. Neither type I PACAP receptor, nor VIP1 receptor mRNA was present within the germ cells. Using the VIP2 receptor probe there was strong labelling within some cross sections of the seminiferous tubuli, while others were not labelled. The in situ results were also confirmed using reverse-transcription PCR (RT-PCR). Our data suggest that PACAP mediates its possible paracrine effect in the testis through the VIP2 receptor.

Animals↗
PubMed1995

Is there a third peripheral catecholaminergic system? Endogenous dopamine as an autocrine/paracrine substance derived from plasma DOPA and inactivated by conjugation.

In mammals, the sympathetic neurotransmitter is norepinephrine (NE), and the main adrenomedullary hormone is epinephrine (EPI). The sources and physiological roles of the third endogenous catecholamine, dopamine (DA), outside the brain have been obscure. Several lines of evidence suggest that in the periphery, rather than DA serving only as the precursor for the active compounds, released from sympathetic nerves and the adrenal medulla, DA may also act as an autocrine/paracrine regulator of local organ function. Thus, in the kidneys, most of DA formation appears to be from proximal tubular uptake of plasma DOPA, and binding of locally formed DA to dopaminergic receptors decreases Na/K ATPase activity and thereby accentuates natriuresis. In the gastric mucosa, DA may modulate sodium absorption and acid secretion. Recent clinical and laboratory animal evidence has indicated that the lungs and mesenteric organs contribute substantially to total body production and metabolism of DA. Generation of DA in non-noradrenergic, non-adrenergic cells can explain why human urine contains higher concentrations of DA and its metabolites than of NE and its metabolites. The vast preponderance of plasma DA in humans is sulfoconjugated. Since patients with sympathoneural failure have normal plasma levels of DA sulfate, one may speculate that the sulfoconjugating mechanism is relatively independent of sympathetic nerves and acts to localize DA effects and inactivate DA entering the circulation. These considerations lead to the concept of a third peripheral catecholaminergic system, where DA derived from plasma DOPA acts as an autocrine/paracrine substance and is inactivated by conjugation.

Animals↗
PubMed1995

Effects of acetaldehyde on nuclear protein binding to the nuclear factor I consensus sequence in the alpha 2(I) collagen promoter.

Acetaldehyde has been shown to increase collagen production in cultured rat myofibroblastlike cells and to activate the mouse alpha 2(I) collagen promoter in transfected NIH 3T3 cells. Nuclear factor I (NF-I), a CCAAT binding transcription factor, is known to bind and activate the alpha 1(I) and alpha 2(I) collagen genes. Activation of the alpha 2(I) collagen promoter was not observed when the NF-I binding site of the promoter was deleted. In this study, we determined if acetaldehyde influences the binding of NF-I to the alpha 2(I) collagen promoter. Nuclear proteins extracted from NIH 3T3 cells, or myofibroblastlike cells, 36 hours after the addition of acetaldehyde (200 mumol/L) in serum-free media showed increased binding to the consensus sequence of the NF-I binding site by DNase I protection analysis and by electrophoretic mobility shift assay (EMSA) as compared with control nuclear extracts that were not exposed to acetaldehyde. Furthermore, nuclear proteins extracted from myofibroblastlike cells that had been previously exposed to acetaldehyde had a marked increase in NF-I protein, as shown by Western blot with NF-I antibodies. Antisera to NF-I resulted in a slow migrating DNA-protein-antibody complex (supershift) on EMSA. However, the NF-I antibody did not supershift all the DNA-protein complexes, and the supershift band was not increased with nuclear proteins from acetaldehyde-treated cells despite the increased binding of these nuclear protein preparations to the NF-I oligo. Therefore, nuclear proteins, in addition to NF-I, bind to the NF-I consensus sequence and may have their binding altered by acetaldehyde.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1994

The adult enhancer factor-1, a Drosophila melanogaster transcriptional repressor, modulates the promoter activity of the rat class-I alcohol dehydrogenase-encoding gene.

Expression of the Drosophila melanogaster alcohol dehydrogenase-encoding gene (ADH) in the adult fat body is controlled by the ADH adult enhancer site (AAE). The D. melanogaster transcription repressor, adult enhancer factor-1 (AEF-1), binds to AAE at a site which overlaps with a sequence recognized by the mammalian transcription factor, CCAAT/enhancer-binding protein alpha [C/EBP alpha; Falb and Maniatis, Genes Dev. 6 (1992a) 454-465]. C/EBP alpha also activates the promoter of the rat class-I ADH gene in a sequence-specific manner [Potter et al., Arch. Biochem. Biophys. 285 (1991a) 246-251]. In this study, we explored the possibility that D. melanogaster AEF-1 influences transcription of the rat class-I ADH. By DNase I footprint analysis, bacterially produced AEF-1 protects a region of DNA between nucleotides (nt) -22 and -36 of the rat class-I ADH promoter (pADH), just 5' to the binding site of C/EBP alpha, a result confirmed by the electrophoretic mobility shift assay (EMSA). Co-transfection of a rat pADH-CAT reporter construct with expression vectors containing C/EBP alpha, AEF-1, or both, indicates that AEF-1 inhibits induction of the rat pADH by C/EBP alpha. Moreover, rat liver nuclear extracts appear to contain AEF-1-like-binding activities to AAE by EMSA. These experiments suggest an evolutionarily conserved mechanism by which AEF-1 modulates expression of the D. melanogaster and rat ADH genes.

Alcohol Dehydrogenase↗
PubMed1994

Acetaldehyde activates the promoter of the mouse alpha 2(I) collagen gene.

The mechanism whereby ethanol ingestion results in hepatic fibrosis remains unknown. Acetaldehyde has been shown to increase alpha 1(I) collagen gene transcription in human fibroblasts and in rat myofibroblastlike cells (Ito cells) in culture. In this study, the effect of acetaldehyde was determined on the activation of the alpha 2(I) collagen promoter. A plasmid containing the mouse alpha 2(I) collagen promoter region (-2000 to 54), fused to the coding sequence of the reporter gene chloramphenicol acetyl transferase and similar plasmid constructs containing deletions in the collagen promoter, were transfected into NIH 3T3 fibroblasts in culture. Acetaldehyde (200 mumol/L) and transforming growth factor-beta 1 (5 ng/ml) activated the wild type promoter. The combination of acetaldehyde and transforming growth factor-beta 1 did not result in a greater effect than either alone. Acetaldehyde inhibited, whereas transforming growth factor-beta 1 did not activate, the promoter, with a -352 to -104 deletion. By contrast, acetaldehyde had no effect, whereas transforming growth factor-beta 1 resulted in a small decrease in the activity of the promoter, with a -501 to -352 deletion. This study shows that acetaldehyde and transforming growth factor-beta 1 independently activate the mouse alpha 2(I) collagen promoter and that this activation is mediated by the same proximal region of the promoter.

Acetaldehyde↗
PubMed1994

Distribution and regulation of the candidate prohormone processing enzymes SPC2 and SPC3 in adult rat brain.

A number of candidate mammalian prohormone processing enzymes related to the yeast Kex2 endoprotease have been cloned and demonstrated to cleave several prohormone precursors at single, pairs and tetra basic amino acid processing sites. We have mapped the distribution of the mRNAs encoding two of these endoproteases in adult rat brain. SPC3 message levels showed a more restricted distribution and generally lower levels than SPC2 transcripts. The highest levels of SPC2 mRNA were found in the pyramidal cells of the hippocampus, several thalamic nuclei, the habenula and selected nuclei in the hypothalamus. SPC3 mRNA was most abundant in dentate gyrus granule cells, the habenula and selected hypothalamic nuclei. In the hypothalamus overlapping and unique distributions of the two transcripts were seen in the paraventricular nucleus with SPC3 mRNA predominantly expressed in lateral magnocellular cells. Both SPC2 and SPC3 mRNA were upregulated in the paraventricular and supraoptic hypothalamic nuclei following chronic salt loading. Combined immunocytochemistry/in situ hybridization histochemistry demonstrated that SPC2 and SPC3 transcripts were both expressed in the vasopressinergic subpopulation of magnocellular neurons in the supraoptic nucleus. SPC3 mRNA, but not SPC2 transcripts, also colocalized with immunoreactive vasopressin-associated neurophysin in the suprachiasmatic nucleus. These results remain consistent with roles for SPC2 and SPC3 in the biosynthesis of neuropeptides and for a specific role for SPC3 in the processing of provasopressin. Increased levels of SPC2 and SPC3 transcripts following a chronic osmotic stimulus suggests these proteases are coregulated with prohormone substrates and may be useful as an indicator of peptidergic activity.

Amino Acid Sequence↗
PubMed1994

A frequent ala 4 to val superoxide dismutase-1 mutation is associated with a rapidly progressive familial amyotrophic lateral sclerosis.

Familial amyotrophic lateral sclerosis (FALS), a degenerative disorder of motor neurons, is associated with mutations in the Cu/Zn superoxide dismutase gene SOD1 in some affected families. We confirm a recently reported ala4-->val mutation in exon 1 of the SOD1 gene and report that this mutation is both the most commonly detected of all SOD1 mutations and among the most clinically severe. By comparison with our other FALS families, the exon 1 mutation is associated with reduced survival time after onset: 1.2 years, as compared to 2.5 years for all other FALS patients. We also demonstrate that SOD1 is prominently expressed in normal motor neurons and that neural expression of SOD1 is not prevented by this exon 1 mutation. Assays of SOD1 enzymatic activity in extracts from red blood cells, lymphoblastoid cells, and brain tissues revealed an approximately 50% reduction in activity of cytosolic SOD1 in patients with this mutation compared to normal individuals. By contrast, patients with sporadic ALS had normal levels of SOD1 enzymatic activity. Why this SOD1 mutation causes motor neuron death in FALS remains to be established. While it may be that FALS is a consequence of loss of SOD1 function, it is also possible that motor neuron death in this dominantly inherited disease occurs because the mutations confer an additional, cytotoxic function on the SOD1 protein.

Age of Onset↗
PubMed1994

Effects of Helicobacter pylori infection and gastritis on gastric alcohol dehydrogenase activity.

Sex and age differences in gastric alcohol dehydrogenase activity in relation to abnormalities of gastric histology and Helicobacter pylori infection were determined in 63 patients (32 men and 31 women) undergoing upper endoscopy for gastrointestinal symptoms. No sex difference was found in gastric alcohol dehydrogenase activity. Males older than 50 years had lower enzyme activity than younger males. Patients with H. pylori and/or moderate to severe chronic and acute inflammation and epithelial mucin depletion had lower alcohol dehydrogenase activity in the antrum, but not in the fundus. H. pylori was found more frequently in the older male patients. Antral alcohol dehydrogenase was most decreased in older patients of both sexes with H. pylori infection. In conclusion, H. pylori infection and/or chronic active gastritis are important causes of low gastric alcohol dehydrogenase activity.

Adult↗
PubMed1994

Potential problems in using [35S]-dATP-tailed oligonucleotides for detecting mRNAs in certain cells of the immune system.

In this study we examined the cause of unusually intense signals obtained in immune cells by in situ hybridization histochemistry using 35S-labeled oligonucleotides. We verified that the phenomenon is an amplification of a specific signal due to a series of chemical interactions after the probe binds to a specific mRNA in the tissue. The presence of oxidative enzymes in the tissue seems to be necessary for this reaction to occur. Therefore, most cells of the immune system (e.g., macrophages, neutrophil and eosinophil leukocytes), being rich in oxidative enzymes, will show some signal amplification. The intensification of the signal can be avoided if MgCl2 is substituted for CoCl2 in the synthesis of [35S]-thiophosphate-labeled probes, if 2,3-dimercaptopropanol [British anti-Lewisite (BAL)] is added to the hybridization buffer, or if [33P]-phosphate is used instead of [35S]-thiophosphate in the labeling of the probes.

Adenosine Triphosphate↗
PubMed1994

Two receptors for vasoactive intestinal polypeptide with similar specificity and complementary distributions.

Vasoactive intestinal polypeptide (VIP) has a variety of physiological effects. Pharmacological evidence suggesting that VIP acts via multiple receptors has been confirmed by the cloning of two VIP receptors (VIP1 and VIP2) with very different amino acid sequences. At both the VIP1 and the VIP2 receptor VIP, PHI, PACAP38, and PACAP27 have similar potency to each other. Only the VIP1 receptor is activated by secretin. The messenger RNAs (mRNAs) for the two receptors have completely different distributions as mapped by in situ hybridization histochemistry. VIP1 receptor mRNA is predominantly found in the lung, small intestine, thymus, and within the brain in the cerebral cortex and hippocampus. VIP2 receptor mRNA is present in a number of areas where VIP acts but VIP1 receptor mRNA is not present, including the stomach and testes. In the CNS VIP2 receptor mRNA is exclusively present in areas associated with neuroendocrine function, including several hypothalamic nuclei. In the periphery, it is also present in the pituitary and in pancreatic islets.

Animals↗
PubMed1994

Evidence for free radical-mediated lipid peroxidation at reperfusion of human orthotopic liver transplants.

BACKGROUND: Generation of toxic oxygen metabolites at reperfusion may contribute to the injury sustained as a consequence of harvest and ischemic preservation of organ allografts. Because there is a paucity of evidence that this mechanism is operative in human beings, we measured the generation of ethane into the exhaled breath as a biomarker of free radical-mediated lipid peroxidation in human liver transplantation. METHODS: A novel technique that increased the previous standard of sensitivity 100-fold was used to measure picomole quantities of ethane in exhaled breath of eight recipients undergoing human orthotopic liver transplantation. RESULTS: Ethane production correlated closely with the specific events of liver transplantation including the initial reperfusion of the allografts. In every case a twofold to threefold increase in ethane production was superimposed on a stable baseline immediately after reestablishment of portal vein blood flow through the donor liver. CONCLUSIONS: Ethane production was interpreted as evidence of hepatic lipid peroxidation, presumably mediated by toxic metabolites of oxygen occurring at reperfusion. This noninvasive approach allowed localization of the time point at which lipid peroxidation occurred and may facilitate quantification of lipid peroxidation mediated by free radicals and other toxic oxygen metabolites during operation.

Adult↗
PubMed1993

Regulation of the rat class I alcohol dehydrogenase gene by growth hormone.

Growth hormone (GH) increases the transcription of the rat class I alcohol dehydrogenase (ADH) gene. Two transcription factors, the CCAAT/enhancer binding protein (C/EBP) and the liver activator protein (LAP), were previously shown to bind to the ADH promoter at nucleotide positions -11 to -22 relative to the start-site of transcription and to activate the ADH promoter in co-transfection experiments. In this study, exposure of cultured rat hepatocytes to GH (1 micrograms/ml) for 4 days increased LAP mRNA, but not C/EBP mRNA, in conjunction with an increase in ADH mRNA. GH, in transient transfection experiments of primary rat hepatocyte cultures, activated an ADH promoter-reporter gene construct containing the C/EBP binding site, but failed to activate a construct containing a 4-bp mutation at this site. These results suggest that the effect of GH in enhancing ADH promoter activity is mediated by LAP binding to the C/EBP site.

Alcohol Dehydrogenase↗