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 livers from a total of 51 Sprague-Dawley rats treated with different doses of N-nitrosomorpholine (80-120 mg/l in the drinking water) for up to 14 weeks together with the livers of 28 control animals were histochemically investigated at the cessation of carcinogenic insult and at varying periods thereafter for their glycogen content, basophilia and activities of various enzymes of carbohydrate metabolism: glycogen synthetase, glycogen phosphorylase, glucose-6-phosphatase, glyceraldehyde-3-phosphate dehydrogenase and glucose-6-phosphate dehydrogenase. The enzymatic patterns of normal tissue, preneoplastic and neoplastic lesions were characterized and compared with reference to the morphologically defined stages of tumor development in the liver. The early appearing glycogen storing areas, localized in the peripheral and intermediate lobular regions, did not show significant changes in the histochemically demonstrable activities of the enzymes tested. After cessation of the carcinogen treatment the more pronounced glycogen storage foci which developed within the aforementioned regions of the liver acinus usually showed a reduction in the activities of phosphorylase and glucose-6-phosphatase while the activity of glucose-6-phosphate dehydrogenase, a key enzyme for the pentose phosphate pathway, was increased. The mixed cell foci, neoplastic nodules and tumors which emerged at later stages were characterized by a progressive shift away from glycogen metabolism towards glycolysis and the pentose phosphate pathway, as indicated by an increase in glyceraldehyde-3-phosphate dehydrogenase and glucose-6-phosphate dehydrogenase activities. These changes in enzyme pattern are supportive of a developmental sequence leading from glycogen storage foci through mixed cell foci and neoplastic nodules to hepatocellular carcinomas.
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PMID:Correlative histochemistry of some enzymes of carbohydrate metabolism in preneoplastic and neoplastic lesions in the rat liver. 629 53

Sprague-Dawley rats were treated with N-nitrosomorpholine (NNM) alone (7 weeks, 120 mg/l in drinking water), with NNM followed by phenobarbital (PB) (750 mg/l for 6 weeks) or PB alone. The livers from these animals were investigated for glycogen content and activities of glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, glycogen phosphorylase and glycogen synthetase. The following parameters proved to be significantly altered in the livers of rats treated with either NNM or PB or both compared with untreated controls: glycogen content was increased and the activities of glucose-6-phosphatase and glycogen synthetase were decreased. Although these data show some similarities in changes of glycogen metabolism of livers treated with NNM or PB, earlier histochemical investigations revealed important differences in the distribution of these alterations within the liver parenchyma.
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PMID:Influence of phenobarbital on glycogen metabolism of rat liver pretreated with N-nitrosomorpholine. 630 40

The livers of rats treated for 12 weeks with N-nitrosomorpholine (80 mg/1 drinking water) were investigated on the day of carcinogen withdrawal (12 + 0 weeks) and 8 weeks after cessation of treatment (12 + 8 weeks). The glycogen content in relation to the DNA and protein content of the liver and the activities of glycogen synthetase, glycogen phosphorylase, glucose-6-phosphatase, and glucose-6-phosphate dehydrogenase were determined in the liver homogenates. The glycogen content of the livers was slightly elevated at both times investigated. Phosphorylase and synthetase activities showed no clear alterations in livers of treated animals as compared with controls. Glucose-6-phosphatase activity was significantly reduced at 12 + 0 weeks and returned to normal values at 12 + 8 weeks. The activity of glucose-6-phosphate dehydrogenase was unchanged at 12 + 0 weeks, but exhibited a significant increase at 12 + 8 weeks. Polyacrylamide gel electrophoresis with staining of the gels by an assay specific for the glucose-6-phosphate-dehydrogenase-catalysed reaction revealed the same pattern of active bands in treated and untreated animals but with higher activities in two bands originating from extracts of nitrosomorpholine-treated livers.
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PMID:Biochemical correlation of glycogen content and activity of some enzymes of carbohydrate metabolism in rat liver during early stages of carcinogenesis. 713 Feb 54

An ultrastructural, morphologic and histochemical study was made on the livers of rats exposed to eight different acute stressors: fasting, cortisol injecions, reserpine injections, restraint, spinal cord transection, immersion in hot water, exposure to cold and forced muscular exercise in a revolving drum. After 48 hours of exposure to stress, electron microscopy of the liver revealed rough endoplasmic reticulum fragmentation and dilatation, glycogen depletion, and mitochondrial enlargment. The most striking change, however, was an increase in the number and size of autophagic vacuoles which were limited by single or multiple membranes. A cytochemical study revealed that in the former case, the vacuolar membranes did not show a glucose-6-phosphatase positive reaction, whereas they did in the latter case. The vacuoles contained acid phosphatase positive material as well as organelles in various stages of degradation. Following exposure to most of the stressors, a marked increase of plasma corticosterone was noted, with a lowered rectal temperature and the appearance of the typical stress triad (adrenal hypertrophy, thymicolymphatic involution and gastrointestinal ulcers). The severity of the morphologic changes appeared to parallel the degree of hypothermia caused by the stressor. The results suggest that autophagy in the liver may be an adaptive response to stressors at the subcellular level.
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PMID:Liver ultrastructure during acute stress. 743 33

We review whole-body radioautography for water-soluble substances and its applications studied to date in our laboratory. To transfer the whole-body section onto a glass slide, Japanese paper was inserted between frozen block and adhesive tape before sectioning. Then the section was dried together with the paper and adhesive tape in a cryotome and applied onto the glass slide coated with a mixture of egg-albumin and glycerin. The whole-body section was transferred to slide and contacted with the film in vacuum. By using these techniques, we review the glucose and taurine metabolism, the glucose-6-phosphatase activity and the insulin receptor.
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PMID:Recent progress in whole-body radioautography. 777 35

Glucuronoxylomannan (AC) from the fruiting bodies of Tremella fuciformis exhibited a significant dose-dependent hypoglycemic activity in normal mice and also showed a significant activity in streptozotocin-induced diabetic mice, by intraperitoneal (i.p.) administration. The activities of AC-derivatives such as a product of AC which side chains had been removed were lower than that of native AC. AC raised the plasma insulin level in normal mice. Administration of AC to normal mice significantly increased the activities of hepatic hexokinase and glucose-6-phosphatase dehydrogenase, but it decreased that of hepatic glucose-6-phosphatase. Furthermore, AC reduced the glycogen content in the liver, increased the total lipid in epididymal adipose tissue, and lowered the plasma cholesterol level. The foregoing results indicated that the hypoglycemic activity of AC in normal mice was at least responsible for the increase of insulin secretion and for the acceleration of glucose metabolism. Single oral administration at a dose of 50-300 mg/kg of AC did not affect the plasma glucose level in normal mice, but continuous oral administrations of the AC solution (0.75 g/l) instead of water for a long time was found to be effective on the plasma glucose level in both experiments of the mice injected once i.p. with streptozotocin (170 mg/kg) at 0 d of AC administration and streptozotocin-induced diabetic mice.
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PMID:[Polysaccharides in fungi. XXXIII. Hypoglycemic activity of an acidic polysaccharide (AC) from Tremella fuciformis]. 801 40

1. The effect of incorporating D2O into the incubation medium on glycolysis and gluconeogenesis by hepatocytes from fasted rats was examined. 2. The substitution by heavy water, D2O, at concentrations from 10 to 40%, stimulated glucose uptake, lactate production and CO2 yields from glucose. At 10 mM glucose, 40% D2O doubled glucose uptake, increased CO2 production by 40%, and increased lactate production by 350%. 3. The stimulation of lactate production decreased at higher glucose concentrations, but was still substantial even at 80 mM glucose. 4. There was no effect on CO2 production above glucose concentrations of 30 mM. 5. Ten percent D2O showed little inhibition of lactate uptake, its oxidation and gluconeogenesis. At 40% D2O the inhibition ranged from 10 to 20%. 6. No effect of D2O on the rate of glucokinase or glucose-6-phosphatase was observed. 7. The concentration of fructose, 2,6-P was not affected by D2O.
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PMID:The effect of D2O on glycolysis by rat hepatocytes. 828 24

Coccinia indica leaves were extracted with 60% ethanol, solvents were evaporated and the residue was suspended in water. This suspension was administered orally at a dose of 200 mg/kg body wt. after 18 h of fasting to normal fed and streptozotocin-induced male diabetic rats (180-250 g). After 90 min the rats were killed, and blood-glucose, hepatic glucose-6-phosphatase, fructose-1,6-bisphosphatase and glucose-6-phosphate dehydrogenase (G6PDH) and red-cell G6PDH were assayed. Blood sugar was depressed by 23% (P < 0.01) and 27% (P < 0.001) in the normal fed and streptozotocin-diabetic rats respectively compared with controls which were given distilled water. Hepatic glucose-6-phosphatase and fructose-1,6-bisphosphatase activities were depressed by 32% (P < 0.001) 30% (P < 0.05) respectively in the streptozotocin-diabetic rats, compared with 19% (P < 0.02) and 20% (P < 0.01) depression in the normal fed controls, whereas both the red-cell and hepatic G6PDH activities were found to be elevated by feeding the extract in the streptozotocin-diabetic and in the normal fed controls. Similar results were obtained with the 95%-ethanolic extract of Momordica charantia. Taken together, these results indicate that Coccinia indica and Momordica charantia extracts lowered blood glucose by depressing its synthesis, on the one hand through depression of the key gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and on the other by enhancing glucose oxidation by the shunt pathway through activation of its principal enzyme G6PDH.
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PMID:Hypoglycaemic activity of Coccinia indica and Momordica charantia in diabetic rats: depression of the hepatic gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and elevation of both liver and red-cell shunt enzyme glucose-6-phosphate dehydrogenase. 838 27

Porphyrins, in combination with light, offer an alternate approach to the treatment of cancer, in the form of photodynamic therapy (PDT). With a view to locate new porphyrins for use in PDT, we evaluated the ability of a novel water-soluble porphyrin, meso-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin (T4CPP) to induce photodamage in membranes, using rat hepatic microsomes as a model system. Hepatic microsomes treated with T4CPP and exposed to visible light showed significant lipid peroxidation, as assessed by the formation of conjugated dienes, lipid hydroperoxides, and thiobarbituric acid-reactive substances. The peroxidation induced was both time- and concentration-dependent. T4CPP plus light also resulted in the destruction of the microsomal enzymes adenosine triphosphatase and glucose-6-phosphatase. Analysis of the products of peroxidation and selective inhibition by specific inhibitors showed that the oxidative damage induced was mainly due to singlet oxygen and partly due to hydroxyl radical. The porphyrin T4CPP was efficiently labeled with 99mTc. When this 99mTc-labeled porphyrin was injected into a mammary-tumor-bearing rat, it accumulated in the tumor. Our studies suggest that T4CPP, due to its potential to localize in tumors and to induce membrane damage as exemplified by alteration in rat liver microsomes, may have possible applications in this new modality of cancer treatment.
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PMID:Photodynamic effects induced by meso-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin using rat hepatic microsomes as model membranes. 905 55

Female albino rats were exposed to methadone over a 35-day period by addition of the drug in their drinking water. The final dose of the drug was 1.8 mg/kg body weight per day. After this period, the drug was withdrawn from some animals for 30 days (postexposure). Compared to unexposed controls, serum glucose levels rose during exposure and returned to control levels postexposure. Oral glucose tolerance tests showed impairment in 35-day drug-exposed animals compared to controls and postexposure. The activities of three key enzymes of glycolysis and three key enzymes of gluconeogenesis were measured in liver during and at the end of the exposure period, as well as postexposure. Compared to unexposed controls and postexposure, specific activities of two glycolytic enzymes in livers of exposed animals-hexokinase and phosphofructokinase 1-were significantly reduced, whereas the activity of a third glycolytic enzyme-pyruvate kinase-was unchanged. The specific activities of two gluconeogenic enzymes-glucose-6-phosphatase and fructose-1,6-biphosphatase-were significantly elevated in the drug-exposed animals compared to controls, whereas the activity of a third enzyme-phosphoenolpyruvate carboxykinase-was unchanged. These data indicate that methadone addiction produces a metabolic state similar to insulin-resistant diabetes.
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PMID:Effect of methadone addiction on glucose metabolism in rats. 911 73


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