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)

For the biochemical characterization of a new transplantable hepatoma derived from the MC-29 virus-induced liver tumor, the macromolecular content and the inducibility of glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, and aryl hydrocarbon hydroxylase were compared in chicken liver and in this hepatoma. The alteration of the nucleocytoplasmic ratio was deduced from measurements of DNA, RNA, protein, and phospholipid contents of the whole cell homogenate and cell fractions. The increased nuclear and decreased cytoplasmic content of macromolecules suggests a dominancy of the nuclei in the tumor cells. Glucose-6-phosphatase and aryl hydrocarbon hydroxylase activities were lower by 60 and 80%, respectively, in the highly proliferating hepatoma than in the liver. In contrast, glucose-6-phosphate dehydrogenase activity increased in the hepatoma. However, enzyme inducers, such as methylcholanthrene, hydrocortisone, and insulin, were able to enhance the activity of these enzymes in the liver but had no stimulating effect on the hepatoma.
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PMID:Biochemistry and enzyme induction in MC-29 virus-induced transplantable avian hepatoma. 17 98

The disorder of gene expression in hepatomas was studied by following certain metabolic alterations (enzyme stimulation, nucleic acid labeling) after glucocorticoid treatment and analyzing the site of action of glucocorticoids. Compared to normal liver, the MC-29 virus-derived transplantable hepatoma (VTH) responded abnormally to glucocorticoids, which failed to stimulate the activity of certain enzymes (glucose-6-phosphatase, aryl hydrocarbon hydroxylase) or to inhibit DNA synthesis. Since the binding capacity of the cytosol steroid receptor was the same in liver and VTH but the interaction between the steroid receptor and DNA was reduced in VTH, it was concluded that structural alterations of chromatin nonhistones--including processed steroid receptor--may be responsible for the lack of physiological responses to steroids in VTH. Furthermore, the increased proportion or repetitive sequences in VTH DNA may be a feature of the disorder of gene regulation in malignant cells.
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PMID:Chromatin alterations and gene function disorder in MC-29 virus-derived hepatoma. 22 7

The administration of medroxyprogesterone acetate (MPA) and phenobarbital (PB) improves liver function in rats with liver damage. This was seen here as increased aryl hydrocarbon hydroxylase (AHH) activity after therapy with MPA or PB in rats with a chemical liver injury, produced by dimethylnitrosamine (DMN). Hepatic glucose-6-phosphatase (G6Pase) activity, an index of glucose metabolism was also normalized in the MPA treated rats. The present study further shows that MPA induced hepatic malic enzyme (ME) and isocitrate dehydrogenase (ICDH) activities and PB enhanced glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and ME activities in the DMN pretreated rats. This suggests that MPA and PB enhanced the capacity of altered liver tissue to generate NADPH, a cofactor in the monooxygenase system, which may, in part, enhance the restoration of drug hydroxylation in the rats. Since G6PDH, 6PGDH and ME participate in glucose metabolism, the finding that the compounds influenced these enzymes in distinct ways, may explain the different effects of MPA and PB on the restoration of glucose metabolism.
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PMID:Medroxyprogesterone acetate and phenobarbital induce NADPH producing enzyme activities in rats with a chemical liver injury. 300 83

Polycyclic hydrocarbon metabolism in male Sprague-Dawley rats following inhalation of aerosolized cadmium chloride (CdCl2) was examined. Constitutive activity of microsomal aryl hydrocarbon hydroxylase (AHH) (benzo(a)pyrene substrate) was monitored in lung and liver homogenates up to 10 days after exposure. Lung AHH activity was reduced by 85% during the first 2 days following cadmium inhalation, and did not return to normal levels until 7 days after exposure. Enzyme activity in the livers of cadmium-treated animals was similarly depressed (by 65%) within 24 hr. Cadmium inhalation also inhibited (by 50%) 3-methylcholanthrene (MC) induction of lung AHH when compared with MC-treated controls. No significant effect on AHH inducibility by MC was noted in liver homogenates from cadmium-exposed animals. Nonspecific microsomal damage appeared not to occur since glucose-6-phosphatase activity in lung was unaffected by cadmium treatment. Although the mechanism of cadmium's action remains unclear, it appears not to involve a direct interaction of the metal with enzyme. The alteration of AHH activity by cadmium may result from injury to a specific cell type within the lung, which may be a major site of pulmonary AHH activity, or may result from modulation of synthesis and/or degradation of heme proteins in the lung. These results suggest that cadmium, under these conditions, markedly reduces the constitutive and inducible activity of AHH in the lung.
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PMID:Lung aryl hydrocarbon hydroxylase: inhibition following cadmium chloride inhalation. 631 93

Four separate continuous lines of human hepatocytes (HH01, HH02, HH09, HH25) were developed from normal liver tissue by subjecting cocultures of human hepatocytes with rat liver epithelial cells in a highly enriched medium to frequent subculturing. The addition of conditioned medium from either the human hepatoma line Hep G2 or one of these stable human hepatocyte lines (HH09) appeared to facilitate establishment of line HH25. These human hepatocyte lines have been in continuous culture for 2 to 5 yr and consist of approximately 95% human cells by analysis of cell surface antigens. Cytogenetic analysis also confirmed the human origin of these cells and showed clonal origin with abnormal ploidy. Cells in these human hepatocyte lines retain morphological features of hepatocytes by both light and electron microscopy. They also retain glucose-6-phosphatase activity and secrete proteins characteristic of hepatocytes, such as albumin, alpha-fetoprotein and transferrin. After incubation with 13 mumol/L dibenz(a,h) anthracene for 24 hr, each line had detectable activity of aryl hydrocarbon hydroxylase, ethoxyresorufin O-deethylase and methoxyresorufin O-demethylase. Thus, these human hepatocyte lines retain important differentiated characteristics of hepatocytes. Derived from normal liver tissue, they appear to be immortalized. They provide a new model system for studying human hepatocellular drug metabolism. These lines may also be useful for studying the regulation of synthesis of albumin, alpha-fetoprotein and other proteins in human hepatocytes, determining the effects of cytokines and growth factors and designing systems to effect gene transfer into human hepatocytes for the purpose of gene therapy.
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PMID:Characterization of human hepatocyte lines derived from normal liver tissue. 751 62

Treating animals with combined radiation and thermal injuries with deproteinized plasma extract promotes the preservation of the coupling of mitochondrial oxidative phosphorylation processes, the enhancement of microsomal monooxygenase, NADPH-oxidase and glucose-6-phosphatase activity and the reduction of hepatic and cerebral lipid peroxidation rates, suggesting its high biological activity, therapeutical efficiency, and pathogenetic rationale for application.
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PMID:[Treatment with deproteinized plasma extract in animals with combined radiation-thermal injuries]. 761 1

Our earlier studies in vitro have shown that eugenol inhibits liver microsomal monooxygenase activities and carbon tetrachloride (CCl4)-induced lipid peroxidation (Free Rad. Res. 20, 253-266, 1994). The objective of the present investigation was to study the in vivo protective effect of eugenol against CCl4 toxicity. Eugenol (5 or 25 mg/kg body wt) given orally for 3 consecutive days did not alter the levels of serum glutamic oxalacetic transaminase (SGOT), microsomal enzymes such as cytochrome P450 reductase, glucose-6-phosphatase (G-6-Pase) xenobiotic-metabolizing enzymes (aminopyrine-N-demethylase, N-nitrosodimethylamine-demethylase and ethoxyresorufin-O-deethylase) and liver histology. Doses of eugenol (5 or 25 mg/kg) administered intragastrically to each rat on three consecutive days i.e. 48 hr, 24 hr and 30 min before a single oral dose of CCl4 (2.5 ml/kg body wt) prevented the rise in SGOT level without appreciable improvement in morphological changes in liver. Eugenol pretreatment also did not influence the decrease in microsomal cytochrome P450 content, G-6-Pase and xenobiotic-metabolizing enzymes brought about by CCl4. Since eugenol is metabolized and cleared rapidly from the body, the dose schedule was modified in another experiment. Eugenol (0.2, 1.0, 5.0 or 25 mg/kg) when given thrice orally i.e. prior to (-1 hr) along with (0 hr) and after (+3 hr) the i.p. administration of CCl4 (0.4 ml/kg) prevented significantly the rise in SGOT activity as well as liver necrosis. The protective effect was more evident at 1 mg and 5 mg eugenol doses. However, the decrease in microsomal G-6-Pase activity by CCl4 treatment was not prevented by eugenol suggesting that the damage to endoplasmic reticulum is not protected. The protective effect of eugenol against CCl4 induced hepatotoxicity is more evident when it is given concurrently or soon after rather than much before CCl4 treatment.
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PMID:The protective effects of eugenol on carbon tetrachloride induced hepatotoxicity in rats. 857 54