Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.5.2 (NQO1)
6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rabbits being repeatedly poisoned with small doses of sodium cyanide, the activity of succinic dehydrogenase in the tissues does not essentially change. The activity of NAD.H2-cytochrome-c-reductase and NAD.H2-diaphorase in the brain, myocardium and kidneys increases. Under histotoxic hypoxia the level of iron in the tissues increases by 52-93%, that of copper--by 28-36%, of zinc--by 21-74% and of cobalt by 28-40%. There existed a positive correlation between the content of iron and the activity of NAD-dependent enzymes. In nonlethal form of histotoxic hypoxia the content of nonhemin iron and the activity of NAD.H2-cytochrome-c-reductase in the mitochondria of the brain increases by 25% and 17%, respectively, and a direct correlation is revealed between them.
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PMID:[Iron, copper, zinc and cobalt content and activity of respiratory metalloenzymes in animal tissues under toxic hypoxia]. 68 69

Slow waves in the small intestine seem to arise in plexuses of neurites with interstitial cells of Cajal. In the colon, slow waves appear to arise at the circular muscle - submucosal interface. We therefore sought a plexus at this surface in the colon in the cat, dog, ferret, opossum, rabbit, rat, guinea-pig and man. Segments from all levels of the colon were stained by the Champy-Maillet osmic acid-zinc iodide method and cut into serial 25 micron sections in the plane of the muscle layers. A dense network of neurites with abundant interstitial cells of Cajal was found at the circular muscle - submucosal interface in all species except rabbit. Neurites in this plexus appeared to arise from the deep plexus of the submucosa (Schabadasch's or Henle's plexus). It was not found in the small intestine and stomach. A similar plexus was found in the interstices of the myenteric plexus in the colon. Interstitial cells of Cajal in both plexuses were positive for the NADH-diaphorase stain, but not for silver impregnation. The possible roles of the plexuses of neurites and interstitial cells of Cajal at the circular muscle - submucosal interface and at the plane of the myenteric plexus in the generation of rhythmic activity in the colon are discussed.
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PMID:Intrinsic nerves in the mammalian colon: confirmation of a plexus at the circular muscle-submucosal interface. 245 50

Recent studies have suggested that large amounts of free zinc may be coreleased during excitatory synaptic transmission at glutamatergic synapses, and may act postsynaptically to decrease actions mediated by N-methyl-D-aspartate (NMDA) receptors, while often increasing neuroexcitation mediated by quisqualate receptors. The present study examined the ability of zinc to alter excitatory amino acid (EAA) neurotoxicity. Murine cortical cell cultures were exposed to EAAs for 5 min in defined solutions, and neuronal cell injury was examined the following day both morphologically and by lactate dehydrogenase assay. Inclusion of 30-500 microM zinc in the exposure solution produced a zinc concentration-dependent, noncompetitive attenuation of NMDA-induced neuronal injury, with an ED50 of about 80 microM. In contrast, zinc produced the same concentration-dependent potentiation of quisqualate neurotoxicity; and with 500 microM zinc, a small potentiation of kainate neurotoxicity was suggested. The effect of zinc on the neurotoxicity of the broad-spectrum agonist glutamate was consistent with these effects on specific agonists, as well as with a previous study showing that glutamate neurotoxicity normally depends predominantly on NMDA-receptor activation. Zinc produced a concentration-dependent reduction in glutamate-induced neuronal injury in a fashion similar to that seen with NMDA, but less effectively. In addition, despite this overall protective effect, zinc paradoxically increased the glutamate-induced destruction of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d)-containing neurons, a subpopulation that was shown in the preceding paper (Koh and Choi, 1988) to exhibit resistance to NMDA receptor-mediated neurotoxicity, and vulnerability to non-NMDA receptor-mediated neurotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Zinc alters excitatory amino acid neurotoxicity on cortical neurons. 338 93

The aim of this study was to describe the architecture of a ganglionated nerve plexus found in the loose connective tissue surrounding the pulmonary vein of the mouse. The input to this plexus was from the vagus nerves and from the stellate ganglia. A large ganglion containing more than 200 neurons was commonly found near the primary bifurcation of the pulmonary vein. The neurons were studied by NADH-diaphorase, zinc iodide-osmium and glyoxylic acid-induced catecholamine fluorescence methods at the light microscopic level, by scanning electron microscopy after the removal of connective tissue, and by transmission electron microscopy. The shape of the neuronal cell bodies was generally a smooth ellipsoid with the average major axis about twice the minor axis. The measured maximum cell diameter ranged from 14 to 42 micron (mean 26 micron). The profile area of individual neurons, as measured from wholemount preparations, ranged from 100 to 800 micron2 (mean 340 micron2) and the calculated neuronal volume ranged from 500 to 12,000 micron3 (mean 3300 micron3). Although there was this wide spread in neuronal size, histograms of cell size showed no separate populations of neurons. Almost all of the ganglionic neuronal cell bodies showed no catecholamine-specific fluorescence, but about 1% of the neurons exhibited a weak green fluorescence. Only a few noradrenergic nerve fibres were seen within the ganglia and these were associated with intraganglionic blood vessels. Small, intensely fluorescent cells were only rarely associated with the ganglia. Neurons and satellite cells formed units which were surrounded by an intraganglionic connective tissue space and a perineurium. Some of the intraganglionic capillaries were fenestrated. Neurons were entirely surrounded by satellite cells and did not appear to have any long dendrites. The generally smooth neuronal cell bodies had short spine-like processes, which were confined to within the satellite cell sheath. Preganglionic nerve fibres formed pericellular baskets of varicose fibres around neurons and made synapses either directly on the cell body or on somatic spines in about equal numbers. No synapses were found in the neuropil at a distance from the neuronal cell body. A few nerve processes were deeply embedded within the neuronal cell body. Clusters of vesicles were found in the cytoplasm of most neurons and were associated with subplasmalemmal densities. These synapse-like structures were mostly directed towards satellite cells, but some were associated with incoming synapses.
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PMID:Fine structure of the autonomic ganglia of the mouse pulmonary vein. 362 38

NAD(P)H-dependent C-nitrosoreductase of porcine heart cytosol was purified 12,000-fold in the presence of NADH with an overall yield of 2.2%. The purification procedure included ammonium sulfate fractionation, gel filtration with Sephadex G-100, ion-exchange chromatography on DEAE-Sephadex A-50, hydrophobic chromatography on Octyl-Sepharose CL-4B, and gel filtration with Sephadex G-200. The purity of the preparation was approximately 90% and the molecular weight of the enzyme estimated by gel filtration was about 60,000. The purified enzyme was composed of two molecular forms, nitrosoreductases 1 and 2, having isoelectric points of 8.45 and 8.6, respectively. A significant amount of zinc was found in the preparation by X-ray fluorescence analysis. The enzyme as it was prepared was colorless, but, after oxidation with p-nitrosophenol followed by gel filtration in the absence of NADH, it showed the absorption spectrum of a flavoprotein. Spectral data indicated the presence of 1 mol of flavin per mol of the enzyme. The molecular turnover number was calculated to be 10,000 nmol p-nitrosophenol reduced to p-aminophenol per min per nmol enzyme at pH 5.8 and 22 degrees C. The activity was inhibited by p-chloromercuribenzoate by 50% at a concentration of 3 x 10(-5) M. Besides the nitrosoreductase activity, the purified preparation showed NAD(P)H-dependent menadione reductase activity. The activities were both strongly inhibited by dicumarol and markedly activated by serum albumin and by Tween 20. These results indicate the probable identity of this enzyme with soluble NAD(P)H dehydrogenase (quinone) [EC 1.6.99.2].
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PMID:Studies on the enzymatic reduction of C-nitroso compounds. V. Molecular properties of porcine heart C-nitrosoreductase and identity of this enzyme with NAD(P)H dehydrogenase. 675 11

The mechanism of reduction of p-nitrosophenol (pNSP) catalyzed by horse liver alcohol dehydrogenase (HADH) and human pi-alcohol dehydrogenase (pi-ADH) has been compared in transient and steady-state experiments. Our results indicate that pNSP reduction catalyzed by these two ADH proceeds by different mechanisms. In one mechanism, shown by Equation 1, pNSP is reduced to p-aminophenol (pAP) via two enzymatic steps (Steps 1 and 3), which are mediated by the nonenzymatic dehydration of p-N-hydroxyaminophenol (pN-OHAP) to 1,4-benzoquinoneimine (BQI) (Step 2). [formula: see text] Pathway (I) is proposed mainly for pi-ADH but can be catalyzed by HADH. However, Step 3 is catalyzed approximately 2 orders of magnitude more slowly by HADH than by pi-ADH. This conclusion is confirmed by the results, which indicate that pi-ADH very efficiently catalyzes the reduction of BQI and 1,4-benzoquinone (BQ) to the corresponding hydroquinones. The kinetic constants determined at pH 7.4 suggest that pi-ADH is a more efficient quinone reductase and nitroso reductase than it is an ethanol oxidase or acetaldehyde reductase. An alternative mechanism of pNSP reduction, shown by Equation 2, is suggested for HADH. In this mechanism, formation of the p-hydroxybenzylnitrenium ion (pNH+P) occurs at the active-site zinc ion of the enzyme (Step 2) and accelerates further nonenzymatic reduction to pAP or hydrolysis to BQ (Step 3). [formula: see text]
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PMID:Mechanism of p-nitrosophenol reduction catalyzed by horse liver and human pi-alcohol dehydrogenase (ADH). Human pi-ADH as a quinone reductase. 798 27

Established cell lines derived from newborn livers of c14CoS/c14CoS and cch/cch mice have been shown to be genetically resistant (14CoS/14CoS cells) or susceptible (ch/ch cells) to menadione toxicity. These differences are due in part to relatively higher levels of reduced glutathione (GSH) and NAD(P)H:menadione oxidoreductase (NMO1) activity in the 14CoS/14CoS cells. The indolic membrane-stabilizing antioxidant 5,10-dihydroindeno[1,2-b]indole (DHII) was shown previously to protect against various hepatotoxicants in vivo and in primary rat hepatocytes. This report describes how the 14CoS/14CoS and ch/ch cell lines provide a valuable experimental system to distinguish the mechanism of chemoprotection by DHII from menadione toxicity. The addition of 25 microM DHII produced a time-dependent decrease in menadione-mediated cell death in 14CoS/14CoS cells, with little effect on ch/ch cell viability. The maximum protective effect occurred at 24 hr, although the concentration of DHII remained constant for 48 hr. The protective effect of DHII correlated with enhanced glutathione levels (234% increase at 24hr), as well as induction of four enzymes involved in the detoxification and excretion of menadione: NAD(P)H:menadione oxidoreductase (NMO1, quinone reductase), glutathione reductase, glutathione transferase (GST1A1), and UDP glucuronosyltransferase (UGT1*06), with 24-hr maximum induction of 707, 201, 171 and 198%, respectively. Other biotransformation enzymes not directly involved in menadione metabolism (glutathione peroxidase, cytochromes P4501A1 and P4501A2, copper-, zinc-dependent superoxide dismutase, and NADPH cytochrome c oxidoreductase) were not induced by DHII. Menadione-stimulated superoxide production was inhibited 50% by DHII only in 14CoS/14CoS cells, and the inhibition required 24-hr preincubation. Pretreatment with DHII also protected both cell types against the menadione-mediated depletion of GSH, and the increase in percent (oxidized glutathione GSSG), an indicator of oxidative stress. These results suggest that DHII does not protect against menadione toxicity by virtue of its antioxidant or membrane-stabilizing properties. Rather, it acts by inducing a protective enzyme profile that migates redox cycling and facilitates excretion of menadione.
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PMID:Mechanisms of protection from menadione toxicity by 5,10-dihydroindeno[1,2,-b]indole in a sensitive and resistant mouse hepatocyte line. 824 Apr 1

One mechanism by which chemicals cause cellular injury is the formation of reactive oxygen species. In vitro studies have shown that metallothionein (MT), a small metal-binding, sulfhydryl-rich, readily inducible protein, can scavenge reactive oxygen species, especially hydroxyl radicals. Nevertheless, whether or not MT protects against oxidative stress in the intact animal is not known. Experimental induction of MT could help to clarify this question, however, it is unclear whether agents that induce MT also influence known antioxidant systems. Therefore, the present study was designed to determine whether the well-known MT inducers are specific for induction of MT or whether they might also influence other hepatic systems that protect against oxidative stress. Male rats were administered cadmium chloride (Cd; 30 mumol/kg, s.c.), zinc chloride (Zn; 1000 mumol/kg, s.c.), alpha-hederin (alpha-H, 30 mumol/kg, s.c.) or lipopolysaccharide (LPS; 1 mg/kg, s.c.) 24 h prior to measurement of antioxidant systems. Zn and alpha-H increased hepatic GSH concentration 20% and 55%, respectively. Cd significantly increased, whereas LPS reduced, the activities of selenium-dependent glutathione peroxidase and glutathione reductase. Glutathione S-transferases were not altered by any of the inducers. Cd also increased DT-diaphorase activity. Cd, Zn and alpha-H all decreased catalase activity 20-35%, while the activity of superoxide dismutase was unaffected by the inducers. The amount of total cytochrome P450 enzymes and cytochrome b5 were decreased by LPS, Cd and alpha-H, while Zn appeared to have no effect. The activities of P450 enzymes towards testosterone oxidation were also decreased by LPS, Cd and alpha-H. In conclusion, all four MT inducers examined affect systems known to protect cells against oxidative stress. Therefore, using these chemicals to determine the in vivo role of MT in protecting against oxidative stress poses difficulties.
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PMID:Effect of several metallothionein inducers on oxidative stress defense mechanisms in rats. 856 Apr 99

Adequate, high and deficient dietary levels of zinc (Zn) were compared in seizure-susceptible EL mice with respect to convulsions and to nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase-positive hippocampal neurons. Diaphorase positivity is associated with nitric oxide (NO) production. Convulsive seizures in the EL mice given the various diets did not differ over 1-4 weeks, but convulsions in EL mice given the Zn-deficient diet for 4 weeks were more effectively suppressed by injection of zonisamide (ZNS) (75 mg/kg intraperitoneally) than in mice receiving high- or adequate-Zn diet for the same period. Numbers of NADPH diaphorase-positive neurons in the CA1/CA2 region of the hippocampal formation were significantly higher in mice given the Zn-deficient diet for 4 weeks than in mice fed adequate Zn. Mice receiving the high-Zn diet for the same period had significantly fewer NADPH diaphorase-positive neurons in the subiculum than mice with adequate Zn. These results suggest that Zn deficiency inhibits convulsive seizures of EL mice, and that dietary Zn influences numbers of NO producing neurons in the hippocampal formation.
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PMID:Influence of dietary zinc on convulsive seizures and hippocampal NADPH diaphorase-positive neurons in seizure susceptible EL mouse. 957 68

The purpose of this study was to determine whether nitric oxide (NO) is present in clinically normal horses under basal conditions and if it increases secondary to naturally acquired small intestinal strangulation obstruction. Thirty-one horses were used; 20 horses with naturally acquired small intestinal strangulation obstruction and 11 clinically normal horses with no signs of gastrointestinal tract disease. Jugular venous blood, abdominal fluid, and urine were collected for NO quantification. Plasma, abdominal fluid, and urine were stored at -70 degrees C until analyzed for NO using a chemiluminescent method. Biopsy specimens collected from the affected jejunal segment, during anesthesia or after immediately after euthanasia, or from the midjejunum of control horses, were divided into subsections for fixation in zinc formalin and cryopreservation in OCT gel. Nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) diaphorase histochemical stains were performed on cryopreserved tissues and inducible nitric oxide synthase (iNOS) and nitrotyrosine immunohistochemical stains were performed on formalin-fixed, paraffin-embedded tissues. There were significantly greater plasma and abdominal fluid NO concentrations in affected horses as compared with controls, but there were no significant differences between horses for urine NO concentrations. There was a significant decrease in NADPH diaphorase stain in mucosal epithelium, vasculature, and leukocytes, and in submucosal plexi in affected horses compared with control horses. There was a significant increase in iNOS staining in mucosal and submucosal leukocytes and in mucosal leukocyte nitrotyrosine staining of the affected compared with control horses. Endothelial NOS and neuronal NOS are present under basal conditions in the jejunum of horses and probably mediate physiologic or cytoprotective effects. Plasma and abdominal fluid, but not urine, NO concentrations increase subsequent to small intestinal strangulation obstruction; this may be associated with increased mucosal and submucosal iNOS staining in leukocytes, which was likely due to increased expression subsequent to stimuli associated with ischemia. The increased nitrotyrosine staining in mucosal leukocytes of affected horses likely reflects the presence of peroxynitrite subsequent to increased NO and superoxide production and may reflect a cytotoxic role of NO in small intestinal strangulation obstruction in horses.
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PMID:Detection and comparison of nitric oxide in clinically normal horses and those with naturally acquired small intestinal strangulation obstruction. 1053 1


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