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:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vitro, streptozotocin (1.0-2.0 mM) fails to exert any immediate effect on the activity of FAD-glycerophosphate dehydrogenase in either pancreatic islet homogenate or freshly isolated intact islets. However, when injected in vivo, streptozotocin (40 mg/kg body weight) lowers the specific activity of the FAD-linked enzyme in islet homogenates within 24 h, whilst causing little change in 2-ketoglutarate dehydrogenase and increasing glutamate dehydrogenase islet activity. In animals which became frankly hyperglycaemic as the result of the injection of streptozotocin, the activity of islet FAD-glycerophosphate dehydrogenase, measured 2 weeks after administration of the B-cell cytotoxic agent, was decreased to 10-20% of its control value. Neither insulin treatment nor riboflavin supplementation affected this enzymic defect. Even when the animals injected with streptozotocin remained virtually euglycaemic, the activity of islet FAD-glycerophosphate dehydrogenase was markedly decreased. This coincided with a preferential impairment of aerobic glycolysis, as judged from the ratio between D-[3,4-14C]glucose oxidation and D-[5-3H] glucose utilization by the islets. It is proposed, therefore, that the administration of sub-diabetogenic amounts of streptozotocin to adult rats represents an alternative and easier approach to the study of B-cell dysfunction in this model of type 2 (non-insulin-dependent) diabetes than does streptozotocin injection in neonatal rats.
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PMID:Streptozotocin-induced FAD-glycerophosphate dehydrogenase suppression in pancreatic islets. Relationship with the severity and duration of hyperglycaemia and resistance to insulin or riboflavin treatment. 832 33

Flow cytometric measurements of the activities of lactate dehydrogenase, glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, glycerol-3-phosphate dehydrogenase, succinate dehydrogenase and glutamate dehydrogenase in single Ehrlich ascites tumour cells are described using a tetrazolium salt/fluorescent formazan reaction. Applying cyano-ditolyl-tetrazolium chloride (CTC) as redox dye indicating enzyme reaction, and DAPI as a fluorochrome for nuclear DNA staining, the bivariate flow cytometric assay of enzyme activity and cell cycle analysis was established. Furthermore, adopting the calibration procedure reported formerly, consisting of biochemical determination and flow cytometry of the same sample performed parallelly, the enzyme activities were expressed in biochemical units. The dehydrogenase activities found in Ehrlich ascites cells were 97.5 fmol H2 per average positive cell during 5 min for lactate dehydrogenase, 69.0, 10.6, 25.3, 29.7, and 19.0 fmol H2 per average positive cell during 20 min for glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, glycerol-3-phosphate dehydrogenase, succinate dehydrogenase and glutamate dehydrogenase, respectively. This quantitative procedure can offer an alternative analytic tool for enzyme cytology.
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PMID:Enzyme activities of six different dehydrogenases in Ehrlich ascites cells measured by flow cytometry. 835 66

The activity of FAD-linked glycerophosphate dehydrogenase (m-GDH), as well as that of glutamate dehydrogenase and both glutamate-oxalacetate and glutamate-pyruvate transaminases, were measured in islet, liver, and splenocyte homogenates from 6- to 7-week-old female nonobese diabetic mice (NOD) and age- and sex-matched control mice. Despite incipient insulitis and euglycemia, the NOD mice displayed both high islet insulin content and elevated insulinemia. The activity of m-GDH, expressed relative to protein content, was not decreased in islets of NOD mice, despite the fact that such a specific activity is lower in splenic lymphocytes than islet cells. In liver homogenates, the activity of m-GDH was even higher in NOD than control mice. It is proposed, therefore, that in this model of insulin-dependent diabetes no primary decrease in islet m-GDH activity occurs, at variance with the situation recently documented in several animal models of non-insulin-dependent diabetes.
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PMID:FAD-linked glycerophosphate dehydrogenase activity in islets, liver, and splenocytes of NOD mice. 837 36

The mitochondrial enzyme FAD-linked glycerophosphate dehydrogenase plays a key role in the glucose-sensing device of the insulin-producing pancreatic B-cell. Its activity was found to be decreased in islet, but not liver, homogenates of BL/Ks-db/db mice, in which diabetes mellitus represents an inherited disease. The decreased activity of FAD-linked glycerophosphate dehydrogenase contrasted with a normal activity of glutamate dehydrogenase and 2-ketoglutarate dehydrogenase in the islets of db/db mice. It is proposed that a site-specific defect of FAD-linked glycerophosphate dehydrogenase in the pancreatic B-cell might represent a far-from-uncommon causal or contributing factor in the pathogenesis of non-insulin-dependent diabetes mellitus.
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PMID:FAD-linked glycerophosphate dehydrogenase deficiency in pancreatic islets of mice with hereditary diabetes. 842 47

Purified rat pancreatic insulin-producing B-cells, which display a 12-fold higher activity of FAD-linked glycerophosphate dehydrogenase than other islet endocrine cells, were exposed for 30 min to 2 mM streptozotocin and subsequently cultured for 2 days in the absence or presence of 2 mM nicotinamide. Streptozotocin decreased by 54% the number of B-cells and, in surviving cells, lowered by 75% the activity of FAD-linked glycerophosphate dehydrogenase, whilst failing to affect that of glutamate dehydrogenase. This coincided with a 42-51% reduction of insulin secretion, when expressed relative to either the DNA or hormonal content of surviving cells. After exposure to streptozotocin, the presence of nicotinamide in the culture medium reduced cell death by 44% and also reduced the deleterious effects of streptozotocin upon both the enzymic and secretory activities of surviving cells. These findings indicate that the decreased activity of FAD-linked glycerophosphate dehydrogenase previously documented in pancreatic islets from streptozotocin-injected rats, as well as the protective effect of nicotinamide thereupon, are not attributable solely to changes in the number of B-cells but also to an altered enzymic activity in surviving B-cells. The latter anomaly may account, in part at least, for an impaired B-cell secretory response to D-glucose.
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PMID:Effect of streptozotocin and nicotinamide upon FAD-glycerophosphate dehydrogenase activity and insulin release in purified pancreatic B-cells. 848 53

The activities of hexokinase isoenzymes, lactate dehydrogenase, cytosolic NAD-linked glycerophosphate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, and glutamate dehydrogenase were measured in homogenates of rat purified pancreatic B and non-B islet cells. In B cell homogenates, the maximal activity of hexokinase and glucokinase was one to two orders of magnitude lower than that of lactate dehydrogenase. The activity of the mitochondrial FAD-linked glycerophosphate dehydrogenase was also much lower than that of the cytosolic NAD-linked glycerophosphate dehydrogenase . A comparable hierarchy in the activity of these enzymes was observed in non-B islet cells. These findings reinforce the view that the preferential stimulation of oxidative glycolysis observed in insulin-producing cells, when exposed to high concentrations of D-glucose, is attributable to a Ca2+-induced activation of the mitochondrial FAD-linked glycerophosphate dehydrogenase, rather than to saturation of the catalytic activity of lactate dehydrogenase.
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PMID:Relevance of lactate dehydrogenase activity to the control of oxidative glycolysis in pancreatic islet B-cells. 861 12

The activities of FAD-linked glycerophosphate dehydrogenase (m-GDH), glutamate dehydrogenase (GlDH), glutamate-pyruvate transaminase (GPT) and glutamate-oxalacetate transaminase (GOT) were measured in purified populations of CD3+ lymphocytes from 55 control subjects, 62 type-2 diabetics and 50 non-diabetic relatives of the latter patients. The activity of m-GDH was measured by both a radioisotopic procedure and colourimetric technique. As judged from these measurements and relative to the paired value for GlDH, the incidence of abnormally low m-GDH activity was significantly higher in type-2 diabetics than in control subjects. Moreover, the paired ratio in reaction velocity between the colourimetric and radioisotopic assay of m-GDH was abnormally high in patients with low m-GDH activity. Low m-GDH activity often coincided with increased GPT activity in plasma or high GPT/GOT ratio in lymphocytes. No obvious clustering of these anomalies was found in relatives of diabetic patients. These findings suggest that an inherited or acquired genomic defect of m-GDH in lymphocytes, and possibly in pancreatic B-cells, may participate to the pathogenesis of non-insulin-dependent diabetes mellitus.
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PMID:FAD-glycerophosphate dehydrogenase activity in lymphocytes of type-2 diabetic patients and their relatives. 879 98

The activities of the mitochondrial FAD-linked glycerophosphate dehydrogenase (m-GDH), glutamate dehydrogenase, alpha-ketoglutarate dehydrogenase, glutamate-pyruvate transaminase (GPT) and glutamate-oxaloacetate transaminase were measured in islet and liver homogenates from fetal, neonatal, adult male, adult female, pregnant and lactating rats. Either parallel or dissociated ontogenic changes were observed in islet and liver homogenates. The activity of islet m-GDH was slightly, albeit not significantly, lower in neonates than in adult rats, comparable in male and female adult animals, unaffected by pregnancy, and increased during lactation. It was much higher in fetal or adult islets cultured for 7 days than in freshly isolated islets from adult rats. In cultured islets from adult rats, the increase in m-GDH activity coincided with a dramatic decrease of GPT activity, a situation the mirror image of that found in several animal models of non-insulin-dependent diabetes mellitus. The intrinsic properties of m-GDH, as judged by comparison of measurements made by either a radioisotopic or a colorimetric procedure, were not identical in islet and liver homogenates and differed between fetal and adult islets, suggesting the existence of distinct iso-enzymes. These findings illustrate adaptive changes of islet enzymes, with exclusive or partial mitochondrial location, in ontogenic situations characterized by a remodelling of fuel homeostasis.
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PMID:Ontogeny of FAD-linked glycerophosphate dehydrogenase in rat pancreatic islets. 879 9

An abnormally low activity of mitochondrial FAD-linked glycerophosphate dehydrogenase (m-GDH), relative to the paired measurement of glutamate dehydrogenase, was found in CD3+ lymphocytes from 4 out of 14 mothers with gestational diabetes mellitus, but in none of 36 control mothers. The low m-GDH activity coincided with an abnormally high incidence of familial history for non-insulin-dependent diabetes. These findings are compatible with the view that an inherited or acquired defect of m-GDH may participate to the pathogenesis of beta-cell dysfunction in a subgroup of patients with gestational diabetes.
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PMID:Low mitochondrial glycerophosphate dehydrogenase activity in lymphocytes of women with gestational diabetes. 910

In terms of glucose sensing by pancreatic islet beta-cells, emphasis is currently placed on both the role of glucokinase, with negligible activity of low-Km hexokinase(s), and the prevalence of the oxidative over non-oxidative modality of glycolysis, a situation tentatively attributed, in part at least, to a low activity of lactate dehydrogenase. Conflicting information is available, however, on the activity of both low-Km hexokinase(s) and lactate dehydrogenase in purified beta-cell homogenates. This issue was reinvestigated, therefore, in two populations of purified rat islet beta-cells selected on the basis of their low (betaL) or high (betaH) content in reduced pyridine nucleotides. The size and protein content of betaH cells represented about twice that of betaL cells. Such was also the case for low-Km hexokinase(s), lactate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, glutamate dehydrogenase and glutamate-alanine and glutamate-aspartate transaminases. Whether in betaH or betaL cells, the activity of low-Km hexokinase(s) was at least as high as or higher than that of glucokinase. In both betaH and betaL, the activity of lactate dehydrogenase exceeded that required to catalyze the full reduction of glucose-derived pyruvate to L-lactate, as estimated from the rate of D-glucose phosphorylation under physiological conditions. These findings thus argue against a low expression of either low-Km hexokinase(s) or lactate dehydrogenase as major determinants of the glucose-sensing device in beta-cells.
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PMID:Enzymic activities in two populations of purified rat islet beta-cells. 1149 57


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