Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Urinary lactate was analyzed in 53 normal children, 7 children with glucose-6-phosphatase-deficient glycogenosis, 1 child with fructose-1,6-diphosphatase deficiency and 1 child with pyruvate dehydrogenase deficiency. Lactate in 24-h urine was expressed as concentration, total excretion, excretion per kg body weight and per 1.73 m2 body surface, and as lactate/creatinine quotient. Of these parameters, the lactate concentration in 24-h urine showed the smallest variation in normal children (0.155 +/- 0.053 mM), whereas in patients with one of the above mentioned enzymopathies 10-300-fold elevations were found. The lactate/creatinine quotient, normal range 0.010 to 0.058 (mM/mM) was also used to correct for unnoticed losses of urine. Both parameters, used in conjunction with blood lactate analysis, are suitable for a first screening of patients with enzymopathies of carbohydrate metabolism, and for the follow-up study of the steady or unsteady state of the patient with an enzyme defect of carbohydrate metabolism.
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PMID:Urinary lactate excretion in normal children and in children with enzyme defects of carbohydrate metabolism. 17 40

The activity of certain hepatic enzymes involved in carbohydrate metabolism was measured in postmortem samples from six cases of Reye's syndrome. The activities of the two exclusively extramitochondrial enzymes, glucose-6-phosphatase and fructose-1,6-diphosphatase, were all within the normal range. Activities of pyruvate carboxylase and pyruvate dehydrogenase, both of which are exclusively mitochondrial enzymes, were below levels, shown by control tissue in every case, the average being 21.7% of the lowest control value for pyruvate carboxylase and 11.6% of that for pyruvate dehydrogenase. Impaired pyruvate metabolism appears to be another feature in Reye's syndrome.
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PMID:Deficient activity of hepatic pyruvate dehydrogenase and pyruvate carboxylase in Reye's syndrome. 19 89

The activities of five mitochondrial enzymes tested in liver from patients with Reye's syndrome were measured. Citrate synthase, glutamic dehydrogenase, succinic dehydrogenase, pyruvate carboxylase, and pyruvate dehydrogenase were all outside of the range shown by control samples and well below them in activity. The activity of two extramitochondrial enzymes, glucose-6-phosphatase, which is a microsomal enzyme, and fructose-1,6-diphosphatase, which is a soluble enzyme, were in the normal range in samples from Reye's syndrome patients. In both muscle and brain the activities of the mitochondrial enzyme, citrate synthase, glutamic dehydrogenase, and succinic dehydrogenase were all within the control range. Pyruvate dehydrogenase was found to be normal in muscle from these patients.
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PMID:Reye's syndrome: preservation of mitochondrial enzymes in brain and muscle compared with liver. 21 43

Hyperinsulinemia was produced in fetal rhesus monkeys for 21 days in the last third of gestation by subcutaneous pork insulin injected at 19 U a day. Plasma insulin concentrations in treated fetuses (N = 4) were 3525 microU/ml. There was no difference in paired pre- and post-treatment fetal plasma glucose concentration. Activity of the hepatic enzymes that promote glucose utilization (glucokinase and hexokinase) and glycolysis (phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase) was unaffected. Similarly, glycogen metabolism enzymes (active and inactive synthase and phosphorylase) were unaltered. Two gluconeogenic enzymes (PEPCK and glucose-6-phosphatase) were diminished in the treated group compared with controls. Fetal hyperinsulinemia enhanced lipogenic and NADPH-producing enzyme activities, as evidenced by a twofold increase in fatty acid synthase and in citrate cleavage enzyme activity. Malic enzyme was absent. Hyperinsulinemia with euglycemia (1) increases the activity of enzymes that participate in lipogenesis, (2) decreases some of those controlling gluconeogenesis, and (3) has no effect on the enzymes of glycolysis.
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PMID:Chronic hyperinsulinemia in the fetal rhesus monkey: effects on hepatic enzymes active in lipogenesis and carbohydrate metabolism. 22 50

Glucose transport and metabolism, and the effect of insulin thereon, was studied using suspensions of rat renal tubules enriched in the proximal component. [U-14C]Glucose oxidation is a saturable process (Km 3.1 +/- 0.2 mM; Vmax 14 +/- 0.2 mumole 14CO2 formed/g tissue protein per h). Glucose oxidation and [14C]lactate formation from glucose are inhibited in part by phlorizin and phloretin: the data suggest that the rate-limiting entry of glucose into the cell metabolic pool occurs by both the Na-glucose cotransport system (at the brush border) and the equilibrating, phloretin-sensitive system (at the basal-lateral membrane). Raising external glucose from 5 to 30 mM markedly increases aerobic and anaerobic lactate formation. Gluconeogenesis from lactate is not affected by variations of glucose concentrations. 24 h after streptozotocin administration, aerobic lactate formation is enhanced, as is the uptake of methyl alpha-D-glucoside by the tubules, while anaerobic glycolysis is depressed. Streptozotocin treatment (ST) increases both the Km and Vmax of glucose oxidation; gluconeogenesis and lactate oxidation are not affected. The effect of streptozotocin treatment on lactate formation are abolished by 1 mU/ml insulin. Streptozotocin treatment increases tissue hexokinase activity, decreases glucose-6-phosphatase, but has no significant effect on fructose-1,6-diphosphatase; phosphoenolpyruvate carboxykinase and pyruvate dehydrogenase. The data demonstrate fast streptozotocin-induced changes in cellular enzymes of carbohydrate metabolism. The enhancing effect of streptozotocin on methyl alpha-glucoside uptake is transient: 8 days after administration of the agent, no significant difference from controls is found. It is concluded that under the given experimental conditions insulin enhances the equilibrating glucose entry by the phloretin-sensitive pathway at the basal-lateral membrane, and transiently inhibits the Na-glucose cotransport system.
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PMID:Glucose transport and metabolism in rat renal proximal tubules: multicomponent effects of insulin. 293 29

The freshwater murrel, Channa punctatus, was exposed to a sublethal concentration of mercuric chloride (3 micrograms/liter) for 120 days and the following effects were examined: changes in the levels of glucose and lactic acid in blood and of glycogen and lactic acid in liver and muscles; rate of absorption of glucose from the intestine; and changes in the activities of glucose-6-phosphatase (G-6-Pase), hexokinase, lactate dehydrogenase (LDH), pyruvate dehydrogenase (PDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), glutamate dehydrogenase (GDH), L-amino acid oxidase (AO), and xanthine oxidase (XO) in brain, gills, intestine, kidney, liver, and muscles. Mercury-treated fish were hypoglycemic and hypolactemic. The glycogen content of liver and muscles remained unaltered but the muscle lactic acid level decreased significantly. The rate of intestinal absorption of glucose was reduced significantly by exposure to mercury. G-6-Pase activity was decreased in all the tissues. Hexokinase activity also decreased in mercury-exposed fish but it was significant only in intestine, kidney, and liver. The activities of LDH, PDH, SDH, and MDH also were decreased significantly except LDH in brain and MDH in kidney where an insignificant decrease and an insignificant increase, respectively, were recorded. GDH and AO activities were elevated in most of the tissues except GDH in gills, and AO in gills and muscles where a decrease was observed. XO activity in brain, gills, and kidneys was significantly elevated, but no marked alteration was noted in other tissues.
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PMID:Effect of mercuric chloride on some biochemical and physiological parameters of the freshwater murrel, Channa punctatus. 608 7

A substance capable of stimulating pyruvate dehydrogenase (PDH) and suppressing glucose-6-phosphatase (G-6-Pase) in a cell-free system was prepared from insulin-treated human placental plasma membranes and peripheral blood mononuclear cells by formic acid extraction. This material was partially purified by molecular-exclusion chromatography, ion-exchange chromatography, and hydroxylapatite chromatography. This was found to stimulate pyruvate dehydrogenase and inhibit glucose-6-phosphatase in a dose-dependent manner. The amount or ability of this substance to stimulate pyruvate dehydrogenase was increased in the proportion to the concentration of insulin. The stimulation of pyruvate dehydrogenase by the factor was eliminated when sodium fluoride was presented in the assay of the activation. This result implied that the activation of pyruvate dehydrogenase was mediated by the stimulation of the phosphatase of pyruvate dehydrogenase complex. Each material isolated from insulin-treated human placental plasma membranes and mononuclear cells shared a number of important characteristics of putative second messengers of insulin action as follows: (i) heat and acid stability; (ii) a similar molecular weight; (iii) increased activity of pyruvate dehydrogenase in a insulin-dependent manner; and (iv) stimulated pyruvate dehydrogenase by the sodium fluoride-sensitive mechanism. This human putative second messenger of insulin action was eluted from the anion-exchange resin AG1-X8 at an ionic strength of 0.3-0.4 M, as well as from the hydroxylapatite column at a phosphate concentration of 0.2-0.3 M.
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PMID:Partial purification from human mononuclear cells and placental plasma membranes of an insulin mediator which stimulates pyruvate dehydrogenase and suppresses glucose-6-phosphatase. 609 86

The congenital lactic acidosis form a heterogeneous group of inborn errors that includes defects of gluconeogenesis, the pyruvate dehydrogenase complex, the Krebs cycle and the respiratory chain. These disorders are not easily classified because of the absence of specific metabolites, difficulties in providing suitable tissue specimens and technical problems with the enzyme assays. The commonest causes of lactic acidosis due to inborn errors are the deficiencies of glucose-6-phosphatase and fructose bisphosphatase, which present with hypoglycaemia, lactic acidosis and hepatomegaly. Pyruvate carboxylase and phosphoenolpyruvate deficiencies vary considerably in both clinical expression and biochemical findings. Neurological symptoms predominate in defects of the pyruvate dehydrogenase complex, and some cases of the spinocerebellar ataxias may be due to partial defects of the pyruvate and 2-oxoglutarate dehydrogenase complexes.
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PMID:Problems in the congenital lactic acidoses. 628 Sep 37

Physiological concentrations of insulin suppressed rat liver microsomal glucose-6-phosphatase activity in vitro. To attest a hypothesis that a putative second messenger of insulin action (insulin mediator) mediated this process, we isolated the low molecular factor from insulin-treated plasma membranes of rat liver, which was acid- and heat-stable substance of a peptide nature. The insulin mediator which was proved to activate the mitochondria pyruvate dehydrogenase suppressed microsomal glucose-6-phosphatase. The insulin mediator was linked to suppression of the gluconeogenic enzyme through the control of non-specific phosphohydroxylase.
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PMID:A putative second messenger of insulin action regulates hepatic microsomal glucose-6-phosphatase. 632 Aug 31

Alterations in the activities of alkaline phosphatase, acid phosphatase, glucose-6-phosphatase, succinic dehydrogenase, pyruvic dehydrogenase and lactic dehydrogenase in liver a teleost fish, Channa punctatus were examined after 7, 15 and 30 days treatments with 5 micrograms/l mercuric chloride. Observations have shown specific effects of Hg on these enzymes for a particular period. However, alkaline phosphatase, acid phosphatase, glucose-6-phosphatase were progressively inhibited by this element. Greater accumulation of Hg in liver after a longer treatment and the respective change in enzyme activity clearly showed a dose-response relationship.
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PMID:Mercurial toxicity in the liver of a freshwater teleost Channa punctatus. 709 18


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