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:1.8.1.4 (diaphorase)
2,754 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The reduction and the potential autoxidation of quinoid compounds may be viewed as taking place in three cell compartments. In microsomal fractions (endoplasmic reticulum) one-electron reduction by NAPDH-cytochrome P450 reductase leads to the formation of semiquinones which rapidly react with oxygen to form the parent quinone and superoxide anions. The formation of superoxide through this futile cycle leads ultimately to other damaging species (H2O2 and .OH). A similar futile cycle in mitochondria involves NADH dehydrogenase. In this instance, mitochondria initiation of such a cycle with quinones results not only in the formation of toxic radical species but also in the diversion of electrons from phosphorylating pathways. The consequent diminution of cellular ATP may have as important a consequence with respect to the toxicity of quinones as the generation of radicals. Finally, cytosolic DT diaphorase, which carries out a two-electron reduction of quinones to more stable hydroquinones, may compete with the one-electron systems and participate in the detoxification of quinones by supplying hydroquinones for conjugation reactions. The extent of quinone-induced damage may thus vary from cell to cell depending on the integration of these pathways.
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PMID:Futile redox cycling: implications for oxygen radical toxicity. 631 61

The usual histologic pattern in acute viral hepatitis (AVH) includes cellular abnormalities predominantly in the perivenular (zone 3) hepatocytes and changes interpreted as representing regenerative activity in the periportal (zone 1) hepatocytes. Enzyme histochemical and ultrastructural studies of livers of 12 patients with AVH were undertaken to see whether these features support the concept of regeneration of hepatocytes in zone 1. The swollen hepatocytes in the perivenular areas were hydropic, with dilated or eccentric rough endoplasmic reticulum and decreased or vesicular smooth endoplasmic reticulum; correspondingly, the glucose-6-phosphatase activity (reflecting, when present, intact and functional endoplasmic reticulum) was markedly decreased. Succinic dehydrogenase and diphosphopyridine nucleotide diaphorase activities, representing mitochondrial enzymes, were limited to the perinuclear or pericanalicular cytoplasm of swollen hepatocytes. gamma-Glutamyl transpeptidase activity was increased. The periportal hydropic hepatocytes were small and arranged in clusters displacing sinusoids. Ultrastructurally, these hepatocytes had nearly normal organelles but scanty smooth endoplasmic reticulum. Activities of the enzymes glucose-6-phosphatase, succinic dehydrogenase, and diphosphopyridine nucleotide diaphorase were weak, although glycogen was abundant. gamma-Glutamyl transpeptidase activity was scanty in these hepatocytes. These findings from enzyme histochemical and electron microscopic studies could be interpreted as evidence of functional deterioration of perivenular swollen hepatocytes and relative functional immaturity of periportal hydropic clustered hepatocytes, suggesting regeneration of zone 1 hepatocytes.
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PMID:Acute viral hepatitis: morphologic and functional correlations in human livers. 669 43

Thirty adrenal glands from patients with adreno-leukodystrophy (ALD) have been studied by light microscopy, three by enzyme histochemistry, three by electron microscopy and two by tissue culture. Cytoplasmic ballooning and striations result from proliferation of smooth endoplasmic reticulum and accumulations of lamellar-lipid profiles and clear clefts (crystalloids). Striated adrenocortical cells, the only pathognomonic adrenal lesion in ALD, display cytoplasmic lamellae, decreased amounts of rough endoplasmic reticulum and depression of several enzymes (alpha-glycerophosphate dehydrogenase, 3 beta-hydroxysteroid dehydrogenase and TPNH diaphorase). The striated cells also demonstrate decreased ability to adapt to changes in microenvironment, both in vivo and in vitro. A blunted response by striated cells to focal peripheral cytolysis leads to cytoplasmic erosion, atrophy and macrovacuoles. ACTH has a pivotal role in the evolution of these lesions. We propose that the pathognomonic lamellae of ALD basically represent bilayers or bimolecular leaflets of very long chain saturated fatty acids, while lamellar-lipid profiles and clefts contain cholesterol esterified to these abnormal fatty acids. The similarity of lamellar-lipid profiles of ALD to cytoplasmic lesions induced by long chain saturated fatty acids suggests that the very long chain saturated fatty acids isolated in ALD are cytotoxic and are responsible for adrenocortical cell dysfunction in this disease.
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PMID:A correlative study of the adrenal cortex in adreno-leukodystrophy--evidence for a fatal intoxication with very long chain saturated fatty acids. 746 18

The 2-(2'-benzothiazolyl)-5-styryl-3-(4'-phthalhydrazidyl) tetrazolium chloride (BSPT)-tetrazolium salt technique for the electron microscopic demonstration of reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) was used to localize nitric oxide synthase in the normal and excitotoxically lesioned rat hippocampus. The reaction product BSPT-formazan was shown to stain membranes predominantly of the endoplasmic reticulum. Apart from singular heavily labeled interneurons, the majority of neurons including pyramidal and granular cells and a few astroglial cells, light microscopically 'unstained', showed labeled membrane portions, but to a by far lesser extent. In lesioned areas some prominantly stained neurons rich in labeled membranes and surrounded by cell debris seemed to be largely preserved. An increased number of ultrahistochemically NADPH-d-stained glial cells, in particular astrocytes, was seen.
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PMID:Glutamate agonist-induced hippocampal lesion and nitric oxide synthase/NADPH-diaphorase: a light and electron microscopical study in the rat. 750 2

This study investigated the localization of NADPH-dependent diaphorase activity within vascular endothelial cells in the rat brain. Light microscope observations showed that in addition to neurons and neuronal processes stained histochemically for NADPH-dependent diaphorase activity, endothelial cells in many medium to large diameter (20-100 microns) blood vessels were also stained. These vessels were either attached to the pial surface or contained within the substance of the tissue. In vascular endothelia, the formazan end-product of the diaphorase reaction was deposited as discrete clusters of darkly stained punctae that were located around the nucleus of these cells. Correlated light- and electron-microscopical examination revealed that the sites of formazan deposition occurred in regions of endothelial cytoplasm devoid of smooth and rough endoplasmic reticulum and of mitochondria. Since endothelial NADPH dependent diaphorase activity co-localizes with the activity of nitric oxide synthase (the synthetic enzyme for nitric oxide) these observations suggest that in vascular endothelial cells nitric oxide synthase may be a highly localized soluble cytosolic enzyme not structurally associated with any subcellular organelle. In addition, specific regions of the smooth muscle cells encircling the larger diameter blood vessels clearly demonstrated NADPH dependent diaphorase activity. Unmyelinated fibres and fibre-plexi surrounding blood vessels on the pial surface were also stained. The results of this study show specific NADPH dependent diaphorase activity in vascular endothelial cells in the rat brain. Therefore, together with neurons, endothelial cells may control nitric oxide-dependent vasodilation thereby regulating local blood flow in the brain.
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PMID:Histochemical localization of NADPH-dependent diaphorase (nitric oxide synthase) activity in vascular endothelial cells in the rat brain. 750 99

This is the first report on the ultrastructural distribution of nicotinamide adenine dinucleotide phosphate-diaphorase activity and neuronal isoform (Type I) of nitric oxide synthase immunoreactivity in perivascular nerves (axons) and vascular endothelial cells. In the Sprague-Dawley rat cerebral basilar artery, positive labelling for nicotinamide adenine dinucleotide phosphate-diaphorase and nitric oxide synthase was localized in axons and the endothelium. Over half (approximately 53%) of the axon profiles examined were positive for nicotinamide adenine dinucleotide phosphate-diaphorase. Labelling of nicotinamide adenine dinucleotide phosphate-diaphorase activity in the axons and endothelial cells was mostly distributed in patches within the cytoplasm. In endothelial cells, a relation between the nicotinamide adenine dinucleotide phosphate-diaphorase-labelling and cytoplasmic vesicle-like structures was seen. In both axons and the endothelium, nitric oxide synthase immunoreactivity was seen throughout the cell cytoplasm and in association with the membranes of mitochondria, endoplasmic reticulum and cytoplasmic/synaptic vesicles (the lumen/content of the vesicles was negative for nitric oxide synthase). Also, microtubules were labelled in nitric oxide synthase positive axon profiles. The nitric oxide synthase-positive axon varicosities were characterized by the presence of spherical agranular vesicles with a diameter of 40-50 nm. Approximately 30% of the axon profiles examined were positive for nitric oxide synthase. The nicotinamide adenine dinucleotide phosphate-diaphorase-positive endothelial cells (approximately 20% of all observed endothelial cell profiles) were more frequently seen than those positive for nitric oxide synthase (approximately 7%). It is suggested that nitric oxide released from both perivascular nerves and endothelial cells may be involved in vasomotor control of cerebral circulation.
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PMID:An ultrastructural study of NADPH-diaphorase and nitric oxide synthase in the perivascular nerves and vascular endothelium of the rat basilar artery. 751 50

NADPH-diaphorase activity, which has been previously reported to be associated with the enzyme nitric oxide synthase (NOS), was localized cytochemically in the pancreatic islets of normal rats. All islet cells types, i.e. insulin-, glucagon-, somatostatin- and pancreatic polypeptide-immunoreactive cells, expressed NAD-PH-diaphorase histochemical activity, whereas the exocrine tissue was almost negative. In streptozotocin-treated rats, only the surviving non-beta cells in the islet periphery were stained. Isolated beta and non-beta cells also expressed intense NADPH-diaphorase activity. By electron microscopy, the enzyme was localized primarily on membranes of the endoplasmic reticulum and nuclear envelope, as previously reported for neurons. In addition the enzyme activity was found in the cis-region of the Golgi complex. These results suggest that the four types of endocrine cells of the islets of Langerhans may contain the NOS-enzyme and thus constitutively produce nitric oxide.
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PMID:Cytochemical localization of NADPH-diaphorase in the four types of pancreatic islet cell. 752 33

The activity of reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) was examined histochemically in the rat cerebellar cortex at the light and electron microscopical level. Different staining patterns were observed depending on the technique used. Electron dense reaction product was seen on distinct membrane portions of the endoplasmic reticulum including the nuclear envelope in most of the neurons and in endothelial cells. Electron microscopically no activity staining was seen in glial cells, including Bergmann cells. The addition of the detergent Triton X-100, usually applied in the light microscopical diaphorase histochemistry, led to a striking diminution in membrane staining. In such preparations inspected electron microscopically formazan formed small granules which were evenly distributed over the cytoplasm.
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PMID:Localization of NADPH-diaphorase/nitric oxide synthase activity in the rat cerebellar cortex: a light and electron microscopical study. 753 9

The recent discovery of the identify of nitric oxide synthase with the reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) has powerfully stimulated the anatomical localization of sites of nitric oxide synthesis in the nervous system. In the present study the widely used light microscopical technique for NADPH-d staining was adapted to the electron microscopical level by applying the tetrazolium salt 2-(2'-benzothiazolyl)-5-styryl-3-(4'-phthalhydrazidyl)tetrazolium chloride (BSPT) which produces an electron-dense reaction product, BSPT-formazan. Predominantly membranes of the endoplasmic reticulum were stained. Apart from singular heavily labeled neurons, a majority of nerve cells, light microscopically "unstained", shows sporadically formazan deposits, and, likewise, but regionally different, a few astroglial cells. Lesions induced by the glutamate agonists quinolinic acid and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) display surviving neurons, which are predominantly stained for NADPH-d. Astroglial cells within lesioned areas exhibit increased amounts of reaction product, apparently as a consequence of enzyme induction.
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PMID:Nitric oxide synthase in the brain: light and electron microscopical findings based on the NADPH-diaphorase reaction. 753 22

Nicotinamide-adenine-dinucleotide phosphate-diaphorase positive cells in the chick thymus were studied at the electron-microscopic level. The formazan, a marker for the enzyme nitric oxide synthase, labelled cystic, undifferentiated, endocrine-like and myoid cells in the medulla. Some lymphoid and reticulo-epithelial cells were also lightly labelled. The reaction product was predominantly bound to the membranes of the endoplasmic reticulum in all the cells labelled and also to the nuclear envelope and outer membrane of mitochondria. The Golgi apparatus and the plasma membrane were free of the reaction product.
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PMID:Ultrastructural localisation of NADPH-diaphorase in the chick thymic medulla. 753 55


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