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:3.1.3.9 (glucose-6-phosphatase)
3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The metabolic disturbances in glucose-6-phosphatase deficiency (von Gierke's disease) are the consequence of hypoglycemia, occurring mostly during the night. Continuous provision of glucose is the aim of every recently introduced treatment procedure. We studied the influence of continuous ambulatory peritoneal dialysis (CAPD) on the metabolic disturbances in a 42-year-old female patient with von Gierke's disease and end-stage renal disease. During six months of CAPD, there were no dialysis-related complications. The metabolic acidosis didn't worsen: arterial bicarbonate and lactate were not changed. Mean glycemia was 118.6 +/- 14.4 mg%. Total lipemia, cholesterol and triglycerides were not different from those before CAPD, despite the fact that all hypolipidaemic drugs were stopped. Three different exchange procedures were compared during the night: no dialysis, one exchange with a 2 L solution without buffer containing glucose 15 g/L and containing glucose 42.5 g/L. The results show that the 4.25% glucose solution prevents hypoglycaemia, and diminishes the increase in lactate and pyruvate concentration. Intraperitoneal glucose normalizes the plasma free fatty acid concentration. A very important result is the disappearance of hypo-insulinism. We conclude that, from a clinical point of view, CAPD is a well-tolerated treatment in von Gierke's disease. The limited results provide some evidence that the use of a 4.25% glucose solution as an overnight exchange, instead of the usual 1.5% solution, can prevent at least partly the glycogenolysis and consequently the metabolic disturbances of von Gierke's disease.
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PMID:Continuous ambulatory peritoneal dialysis (CAPD) in a patient with glucose-6-phosphatase deficiency. 248 95

Studies were performed to determine whether hypoglycemia or the glucagon response to hypoglycemia increases uric acid production in glycogen storage disease type I (glucose-6-phosphatase deficiency). Three adults with this disease had hyperuricemia (serum urate, 11.3-12.4 mg/dl) and reduced renal clearance of urate (renal urate clearance, 1.1-3.1 ml/min). These abnormalities were improved in one patient by intravenous glucose infusion for 1 mo, suggesting a role for hypoglycemia and its attendant effects on urate metabolism and excretion. A pharmacologic dose of glucagon caused a rise in serum urate from 11.4 to 13.0 mg/dl, a ninefold increase in urinary excretion of oxypurines, a 65% increase in urinary radioactivity derived from radioactively labeled adenine nucleotides, and a 90% increase in urinary uric acid excretion. These changes indicate that intravenous glucagon increases ATP breakdown to its degradation products and thereby stimulates uric acid production. To observe whether physiologic changes in serum glucagon modulate ATP degradation, uric acid production was compared during saline and somatostatin infusions. Serum urate, urinary oxypurine, radioactivity, and uric acid excretion increased during saline infusion as patients became hypoglycemic. Infusion of somatostatin suppressed these increases despite hypoglycemia and decreased the elevated plasma glucagon levels from a mean of 81.3 to 52.2 pg/ml. These data suggest that hypoglycemia can stimulate uric acid synthesis in glucose-6-phosphatase deficiency. Glucagon contributes to this response by activating ATP degradation to uric acid.
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PMID:Hyperuricemia in glycogen storage disease type I. Contributions by hypoglycemia and hyperglucagonemia to increased urate production. 285 25

Salmon (Oncorhynchus kisutch) somatostatin (sSS; 4 or 8 ng/g body wt) or synthetic Gillichthys urotensin II (UII; 2 or 4 ng/g body wt) were injected intraperitoneally into juvenile freshwater coho salmon. Both sSS and UII caused a dose-dependent increase in plasma free fatty acids (FFA) which diminished with time. sSS induced an initial (1 hr) transient hyperglycemia. By contrast, UII tended to induce hypoglycemia, this effect being significant 5 hr after injection of the higher dose. Both sSS and UII depressed plasma insulin titers 1 hr after injection. By 3 hr, the sSS-associated insulin depression was no longer observed. UII treatment induced a hyperinsulinemia which was present 3 and 5 hr after peptide administration. Although no decreases in liver total lipid concentration or in mesenteric fat total tissue mass were observed, lipolytic enzyme activity within each depot was significantly enhanced by both peptides. Neither sSS nor UII altered 3H2O incorporation into fatty acids or neutral lipids. However, enhanced lipogenesis, particularly by UII, was indicated by increased NADPH production resulting from glucose-6-phosphate dehydrogenase activity. Both sSS and UII enhanced glucose mobilization, as indicated by decreased liver glycogen content and increased liver glucose-6-phosphatase activity. UII, but not sSS, stimulated glycogen synthetase activity. These results suggest that both sSS and UII stimulate hyperlipidemia by enhancing depot lipase activity and that although both factors are potentially gluconeogenetic, sSS seems to be glycogenolytic and hyperglycemic, whereas UII may channel glucose to FFA synthesis.
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PMID:Effects of somatostatin-25 and urotensin II on lipid and carbohydrate metabolism of coho salmon, Oncorhynchus kisutch. 288 97

The effect of fetal hypoglycemia and hypoinsulinemia on fetal rat hepatic glucose-6-phosphatase activity was studied. Fetal hypoglycemia and hypoinsulinemia were produced by inducing maternal hyperinsulinemia and hypoglycemia secondary to the exogenous administration of insulin via implantation of osmotically driven minipumps on day 15 of gestation into 15 experimental animals. 13 animals served as sham-operated controls. Cesarean sections were performed on day 20 or 21 of gestation under pentobarbital anesthesia. Liver glucose-6-phosphatase activity was increased in the hypoinsulinemic fetuses. In contrast, the hyperinsulinemic mothers had suppressed hepatic glucose-6-phosphatase activity. Hypoinsulinemia would appear to be the primary stimulus for enhanced fetal glucose-6-phosphatase in this model.
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PMID:Induction in utero of hepatic glucose-6-phosphatase by fetal hypoinsulinemia. 298 86

The evaluation of hepatic degradation of glycogen in patients with different chronic liver diseases was carried out on the basis of: a) specific activities of hepatic enzymes involved in catabolism of glycogen; b) level of glycogen in liver biopsies; c) concentration of glucose and cAMP in serum after the intravenous administration of glucagon. In 13 out of 35 patients investigated the activity of glucose-6-phosphatase was decreased to 14-50% of the control value. In the livers of 3 patients glycogen phosphorylase activity was decreased to 10% of the control value. In patients with the significantly low activities of hepatic glucose-6-phosphatase and phosphorylase a, however, normal catabolism of glycogen in the liver was observed, neither hypoglycemia nor abnormal glycogen storage in liver biopsies nor abnormal response to glucagon being found. In the group of patients with decreased and normal activities of glucose-6-phosphatase and phosphorylase a, biochemical parameters in the serum (i.e. markers of liver damage) were not detectable. Possible causes of the selective and asymptomatic decrease in the activities of glucose-6-phosphatase and phosphorylase a are discussed.
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PMID:Asymptomatic decreased activities of hepatic glucose-6-phosphatase and glycogen phosphorylase in a number of children with chronic liver disease. 300 Sep 5

Treatment of rats with hypoglycaemic doses of hypoglycin has been shown to abolish the relative detritiation of [2-3H,U-14C]glucose [Osmundsen, Billington, Taylor & Sherratt (1978) Biochem. J. 170, 337-342], indicating that both the Cori and the glucose/glucose 6-phosphate cycles were inhibited in vivo. This inhibition was confirmed and, in addition, it was shown that the conversion in vivo of both [14C]lactate and [14C]fructose into glucose was decreased after hypoglycin treatment. These results suggest that hypoglycin poisoning results in the inhibition in vivo of glucose-6-phosphatase activity, which participates in the overall inhibition of gluconeogenesis and hypoglycaemia. Clofibrate feeding apparently protected the rats against the inhibition of the fructose-to-glucose conversion by hypoglycin. However, in isolated hepatocytes prepared from hypoglycin-treated rats, the conversion of [14C]fructose into glucose and the recycling of [2-3H,U-14C]glucose were not different from that in control hepatocytes. This suggests that the inhibition was lost during preparation of the hepatocytes. The direct measurement of glucose-6-phosphatase activity showed that it was inhibited when measured in concentrated, but not dilute, homogenates prepared from hypoglycin-treated rats.
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PMID:Inhibition of gluconeogenesis by hypoglycin in the rat. Evidence for inhibition of glucose-6-phosphatase in vivo. 303 Feb 85

Liver metabolism of two patients (aged 15 and 23 yr) was studied by P-31 magnetic resonance spectroscopy at 1.9 tesla. The P-31 spectra of liver showed the resonances of phosphomonoesters (including sugar phosphates), inorganic phosphate (Pi), phosphodiesters (e.g. glycerophosphorylcholine, glycerophosporylethanolamine), and ATP. These resonances were quantified by expressing their peak areas in mM (assuming that ATP concentrations in normal liver is 2.5 mM) or as a ratio relative to the area of the phosphodiester resonance. After an overnight fast liver phosphomonoesters in patients were 2.6 and 1.6 AU, respectively (controls 1.1 +/- 0.5, mean +/- 2 SD, n = 17). At the same time liver Pi was decreased in patients to 1.3 and 1.0, respectively (controls 1.8 +/- 0.8). Based on chemical shift measurements the increase in phosphomonoesters could be attributed to accumulation of sugar phosphates (mainly glycolytic intermediates). After 1 g/kg oral glucose, hepatic sugar phosphates decreased in patients by 64 and 40%, respectively, and reached normal levels (on the absolute intensity scale); whereas liver Pi increased by 130 and 40%, respectively. Liver Pi levels remained elevated in both patients 30 min after ingestion of glucose. Liver sugar phosphates and Pi did not change in control subjects (n = 4) after glucose. In contrast to some previous reports, we have found accumulation of glycolytic intermediates in the liver of glucose-6-phosphatase-deficient patients during fasting. In these patients high levels may enhance the activity of residual glucose-6-phosphatase thus increasing hepatic glucose production and reducing the degree of hypoglycemia during fasting.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Study of liver metabolism in glucose-6-phosphatase deficiency (glycogen storage disease type 1A) by P-31 magnetic resonance spectroscopy. 316 98

A four-month-old boy affected by glycogen storage disease type I is presented. The child suffered from hepatomegaly, lactic acidosis, fasting hypoglycemia and failure to thrive. He had repeated infectious and cyclic neutropenia. Immunoglobulin and chemotactic neutrophil motility was impaired. Liver biopsy showed increased amounts of glycogen in hepatic cells as assessed by morphological and biochemical grounds. The activity of glucose-6-phosphatase as well as other glycogenolytic enzymes was normal in the frozen liver. The aforementioned characteristics suggested the diagnosis of glycogen storage disease type Ib. The child was first treated by enteral continuous feeding and later on by frequent meals during the daytime and enteral continuous feeding during the night time, improving the hypoglycemia as well as the other biochemical and metabolic abnormalities.
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PMID:[Present-day status of glycogenosis Ib. Report of a new case]. 319 58

Patients with deficient activity of hepatic glucose-6-phosphatase (glycogen storage disease type I [GSD-I]) have fasting-induced hypoglycemia, lactic acidemia, hyperuricemia, hyperlipidemia, and a markedly increased capacity for ethanol elimination. The mechanism(s) responsible for the rapid ethanol elimination is not known but has been thought to be directly related to the enzyme defect. We postulated however, that the increased elimination of ethanol was an adaptive phenomenon that would revert toward normal with correction of other blood abnormalities by long-term maintenance of normal blood glucose concentration. Six patients were observed before treatment (group A), and four of the six were observed again 3 to 6 months after dietary treatment had normalized all blood abnormalities (group B). Patients received 16 ml/m2 absolute ethanol as a 5% solution in 0.9% sodium chloride over a 20-minute period. The rate of ethanol elimination was significantly greater (P less than 0.03) in group A than in group B (55.1 +/- 11.1 vs. 37.5 +/- 8.6 mg/dl/hr). Changes in lactate level after ethanol were also significant between the two groups (P less than 0.005). Group A showed a decrease from 9.4 +/- 0.5 to 6.4 +/- 0.4 mEq/L, whereas group B showed an increase in lactate level from 2.7 +/- 0.2 to 4.4 +/- 0.64 mEq/L. Ethanol induced no significant change in blood glucose concentration in group A, whereas there was a significant increase (P less than 0.03) in group B from 93 +/- 6 to 123 +/- 9 mg/dl.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rapid ethanol elimination in patients with type I glycogen storage disease is an adaptive change resulting from recurrent hypoglycemia. 345 5

1. The effect of adrenalectomy on the adjustments of carbohydrate metabolism to fasting was studied in rats fed a high-protein, carbohydrate-free (HP) diet. 2. Fasting for 24 h induced a 20% decrease of blood glucose levels in intact rats on the balanced, control (C) diet, but did not affect the blood glucose levels of rats adapted to the HP diet. After adrenalectomy, HP rats lost their capacity to maintain constant blood glucose levels during fasting, but the reduction in blood glucose (30% after 24 h) took longer to appear and was 50% smaller than in adrenalectomized C-rats. 3. Intact rats on the control diet responded to fasting with increased in vitro hepatic gluconeogenic capacity as well as increased phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase activities. Adrenalectomized C-rats also responded to fasting with increased gluconeogenesis and PEPCK activity. In contrast, for both intact and adrenalectomized HP-fed rats, liver gluconeogenesis and PEPCK activity, which were already high in the fed state, did not change or even decreased slightly after fasting. 4. After food restriction, the rates of glucose replacement by adrenalectomized rats on the control diet were higher than those of intact animals on the same diet. This effect was not observed in HP-fed rats, in which the rates of glucose replacement were even slightly lower in adrenalectomized than in intact animals. 5. These data suggest that the mechanism of fasting-induced hypoglycemia after adrenal removal is different for HP and control rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of adrenalectomy on glucose homeostasis in rats fed a high-protein, carbohydrate-free diet. 369 60


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