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 of rats given either the peroxisome proliferating hepatocarcinogen di(2-ethylhexyl)phthalate (DEHP) following initiation by 2-acetylaminofluorene (AAF) or the neoplasm promoter phenobarbital (PB) were studied for changes in 8 histochemical properties. Male F344 rats were fed 200 ppm AAF for 7 weeks to induce hepatocellular altered foci, and were then fed diets containing either no chemical, 12,000 ppm DEHP or 500 ppm PB for 24 weeks. In hepatocytes, DEHP increased alkaline phosphatase activity throughout the lobule, but reduced gamma-glutamyltransferase (GGT) activity in periportal hepatocytes. PB, in contrast, increased GGT activity in periportal hepatocytes. In foci that were induced by AAF, DEHP reduced the histochemical activity of GGT and did not increase the number, mean volume or volume % of foci detected by deficiencies in iron storage, glucose-6-phosphatase, adenosine triphosphatase or fibronectin. PB enhanced the expression of all 8 phenotypic abnormalities in foci such that either more profiles were detected or the area of foci was increased.
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PMID:Effects of the peroxisome proliferator di(2-ethylhexyl)phthalate on enzymes in rat liver and on carcinogen-induced liver altered foci in comparison to the promoter phenobarbital. 197 53

In order to evaluate the usefulness of key gluconeogenic enzymes, in relation to the markers commonly used (alkaline phosphatase and gamma-glutamyl transpeptidase) for the diagnose of cholestasis the serum activity of phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose-6-phosphatase has been measured in rats with bile-duct ligation. Among the gluconeogenic enzymes studied only phosphoenolpyruvate carboxykinase activity increased significantly in the first 48 hours after cholestasis, decreasing thereafter to normal values. Both alkaline phosphatase and gamma-glutamyl transpeptidase activities showed a very significant increase which persisted throughout the experiment. These results seem to indicate that in spite of the high organ specificity of these enzymes they do not appear to be useful for the diagnosis of cholestasis.
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PMID:Evaluation of key gluconeogenic enzymes in experimental biliary obstruction. 198 72

The purpose of this study was to determine if the dietary antioxidant selenium could inhibit hepatocarcinogenesis induced by peroxisome proliferators, which are hypothesized to induce tumors by increased production of hydrogen peroxide or other reactive oxygen species. Rats were fed diets containing the peroxisome proliferator ciprofibrate and one of three concentrations (0.04, 0.2, or 1.0 ppm) of selenium for 6 or 21 months. The incidence of hepatic tumors and the number and volume of gamma-glutamyl transpeptidase-positive, ATPase-negative, glucose-6-phosphatase-negative, and glucose-6-phosphatase-positive foci at 21 months were lower in rats fed higher levels of selenium (no foci or tumors were seen at 6 mo). Indices of oxidative damage in the liver (thiobarbituric acid reactants, conjugated dienes, and lipid-soluble fluorescence products), however, were not decreased in rats fed the high-selenium diet. Therefore, selenium was protective against ciprofibrate-induced hepatocarcinogenesis, but not by reducing the degree of oxidative damage. The liver selenium and glutathione concentrations, and liver selenium-dependent glutathione peroxidase activity, increased as dietary selenium increased. Therefore, inhibition of carcinogenesis by selenium was correlated with increased levels of glutathione and glutathione peroxidase, but these did not inhibit the indices of oxidative damage. Peroxisomal beta-oxidation also increased with the dietary selenium content; it therefore does not appear to be a factor in the inhibition of hepatocarcinogenesis in rats fed higher levels of selenium.
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PMID:Effect of dietary selenium on the induction of altered hepatic foci and hepatic tumors by the peroxisome proliferator ciprofibrate. 208 22

It is shown that peroxidation of phosphatidylcholine (PC) is enhanced in liver of mice fed a hepatocarcinogenic choline-deficient diet containing 0.1% w/w ethionine. Mice were divided into 4 groups and fed for 4 weeks one of the following diets: choline-supplemented; choline-supplemented containing ethionine; choline-deficient; and choline-deficient containing ethionine. Phosphatidylcholine hydroperoxide (PCOOH) of liver lipids was measured by high performance liquid chromatography using a chemiluminescence detector. Mice fed a choline-deficient diet containing ethionine showed 6-fold higher PCOOH levels than the choline-supplemented control mice: the PCOOH/PC molar ratios of liver lipids were 32.3 X 10(-5) and 5.6 X 10(-5), respectively. In addition to this remarkable degree of lipid peroxidation in liver of mice fed the choline-deficient diet containing ethionine, we also observed a significant liver fatty infiltration, a decrease in plasma and liver alpha-tocopherol, and an increase in liver injury-indicative enzyme activities. Also, marker enzymes for hepatocarcinogenesis, glucose-6-phosphatase and gamma-glutamyl transpeptidase were affected. These data suggest that enhanced hydroperoxidation of phosphatidylcholine may participate in hepatocarcinogenesis provoked by choline deficiency in the presence of ethionine.
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PMID:Liver phosphatidylcholine hydroperoxidation provoked by ethionine-containing choline-deficient diet in mice. 225 May 95

Among the therapeutic alternatives to orthotopic liver transplantation, hepatocyte transplantation (HT) offers the best potential in a number of liver diseases, mainly inborn errors of metabolism. Nevertheless, HT presents several inconveniences such as the scarce knowledge of the functionality of the transplanted hepatocytes, which has given rise to controversy about the specificity or unspecificity of the transplant, and the lack of a suitable system for preserving the cells. This study was designed to test a system for cryopreserving hepatocytes and to assess their functionality over prolonged periods after their ectopic transplantation. A medium and a freezing schedule which are reproducible and yield elevated viability have been used, and a number of hepatospecific parameters have been assessed: the activity of ornithine carbamoyltransferase--an enzyme of primary importance in the urea cycle--lipogenesis, gluconeogenesis, glucose-6-phosphatase and cytochrome oxidase activities, the presence of albumin--as an index of plasma protein synthesis--and IDA uptake and metabolism, showing the UDP-glucuronyl transferase activity. As dedifferentiation markers, gamma-glutamyl transpeptidase and alpha-fetoprotein have been studied. From the results, it can be deduced that hepatocytes can be cryopreserved and transplanted and that under these conditions they maintain hepatic features for a long time. Following transplantation, several specific liver functions appear or are enhanced in the spleen. Freshly isolated and cryopreserved transplanted hepatocytes have similar behaviors, although a difference in the expression of the function can be observed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Auxiliary liver by transplanted frozen-thawed hepatocytes. 229 77

The ability of methyl-deficient, amino-acid-defined diets to produce enzyme-altered foci was quantitatively determined in the livers of rats treated both with and without an initiating dose of diethylnitrosamine (DEN). Male weanling F-344 rats were fed a complete, amino-acid-defined diet for 1 week. They were then injected i.p. with a single dose of DEN (20 mg/kg body weight) and fed the complete diet for an additional week. Forty animals in each dose group were then maintained for 5-38 weeks on the complete diet (diet 1) or one of the three methyl-deficient diets customarily used in this laboratory: diet 2, devoid of methionine and choline; diet 3, devoid of methionine only; and diet 4, devoid of choline only. In diets 2 and 3, methionine was replaced by equimolar amounts of its metabolic precursor, DL-homocystine. Ten animals per group were killed 8, 12, 17, 24 and 41 weeks after DEN initiation. For 2 weeks prior to being killed, each group was maintained on the complete diet to minimize the histological abnormalities due to acute toxicity of the diets. Serial sections of the livers were obtained, stained sequentially for gamma-glutamyltranspeptidase, ATPase and glucose-6-phosphatase, and the quantitation of the focal lesions scored by these markers was carried out by quantitative stereology. The results indicated that, regardless of the enzyme marker(s) examined, there was a general correspondence between the volume and number of altered hepatic foci (AHF) formed and the previously described tumor-promoting activities of each diet. Thus, while all DEN-treated groups contained significant numbers of AHF 24 weeks after initiation, only the diet-2-fed animals displayed such foci at 8 weeks. Similarly, among the uninitiated rats, only those fed diet 2 exhibited the presence of AHF throughout the experimental period. Interestingly, the livers of uninitiated, choline-deficient rats showed a small number of AHF at 24 and 42 weeks; these foci were not observed at all in the corresponding DEN-untreated animals fed diet 3, deficient in methionine only. The results provide evidence that the carcinogenic effects of the methionine- and choline-deficient diet result more from its strongly promoting effect than from any initiating activity by the diet.
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PMID:The effect of choline and methionine deficiencies on the number and volume percentage of altered hepatic foci in the presence or absence of diethylnitrosamine initiation in rat liver. 230 54

Liver carcinogenesis was induced in rats by aflatoxin B1 (AFB1) enhanced by a choline-deficient diet. In Experiment 1, the ornithine decarboxylase inhibitor, alpha-difluoromethylornithine (DFMO), was administered by gavage to one group only during AFB1 administration; another group received DFMO during AFB1 administration and for 2 months after carcinogen administration. These two groups were compared to two control groups, one given AFB1 and fed the choline-deficient diet and another fed the deficient diet only. In a second experiment, DFMO was administered at a concentration of 2% in the water for 3 weeks and then at 1% for the remainder of the study. Rats from each group in Experiment 1 were killed at 2, 8, and 10 months after AFB1 administration and the development of tumors was followed by histology; autoradiography of [3H]thymidine incorporation into DNA; enzyme histochemistry; and alpha-fetoprotein determination. The group given DFMO during AFB1 administration was not significantly different from the AFB1-treated control group at 2 and 8 months after AFB1 administration. However, at 10 months following AFB1 and DFMO administration, the [3H]thymidine-labeling index and glucose-6-phosphatase staining were significantly increased. This group had three animals bearing hepatocellular carcinomas as compared to none in the controls. The group given DFMO for 2 months after AFB1 administration had a significantly depressed growth rate 2 months later, but this difference was not apparent after 8 months. After 10 months, there was a significantly increased [3H] thymidine-labeling index and increased volume fraction of gamma-glutamyltranspeptidase in the AFB1-DFMO-treated group as compared to the controls. DFMO appeared to inhibit growth under some conditions, but if administration was discontinued after AFB1 exposure, it appeared to enhance tumorigenesis. In Experiment 2, where a larger dose of AFB1 was used and DFMO was administered in the water from start to finish of the experiment, DFMO inhibited tumor induction and depressed the appearance of markers examined during carcinogenesis. These data indicate that the regimen used for DFMO administration can markedly affect tumor induction.
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PMID:Effects of the irreversible ornithine decarboxylase inhibitor, alpha-difluoromethylornithine, aflatoxin B1, and choline deficiency on hepatocarcinogenesis. 241 77

Portacaval shunt (PCS) operations were performed on male inbred SD rats. The activity of liver gamma-glutamyltranspeptidase (GGT) increased a few days after the operation and remained high after several months. However, the activity was only present in periportal areas of liver lobules and was mainly restricted to the endothelial lining cells of periportal blood vessels. Phenobarbital sodium (CAS: 57-03-7) administration did not change the distribution of GGT. The activity of liver glucose-6-phosphatase disappeared in the centrilobular areas a few days after the operation but was present in the periportal areas. The distribution of this activity returned to normal after several months. The capacity of liver cells to store glycogen was significantly decreased following the PCS operation. Morphologic changes in hepatocytes observed after the PCS operation did not show similarities to those seen in preneoplastic livers. The nuclei of the small compact hepatocytes found in the animals with PCS were irregular in shape and stained intensively with hematoxylin and eosin. The large pale-staining cells in the periphery of liver lobes were GGT negative and their nuclei had a normal morphology. Neither morphologic nor histochemical changes consistent with preneoplastic and/or neoplastic stage were observed after 10 months in the liver when the PCS operation was performed on rats having received an ip dose (10 mg/kg) of diethylnitrosamine (CAS: 55-18-5) 2 weeks prior to the operation.
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PMID:Histochemical changes in livers from portacaval-shunted rats. 242 Oct 39

The relationships between the gross appearance, histologic types, and cytochemical characteristics of hepatocellular neoplasms were studied in B6C3F1 mice given the liver carcinogen diethylnitrosamine either alone or followed by the organochlorine pesticides, 4,4'-dichlorodiphenyltrichloroethane, chlordane, or heptachlor as promoting agents. Hepatocellular neoplasms were categorized according to their cytoplasmic staining properties with hematoxylin and eosin. Acidophilic neoplasms more often displayed increased activity of alkaline phosphatase than did basophilic neoplasms. The activities of glucose-6-phosphatase and adenosine triphosphatase were decreased in both acidophilic and basophilic neoplasms. There was no difference in the activities of these enzymes or gamma-glutamyltranspeptidase between adenomas and carcinomas, although most neoplasms did not display gamma-glutamyltranspeptidase. Chlordane or heptachlor exposure increased the alkaline phosphatase activity in neoplastic cells, but not that of other enzymes. The majority of neoplasms displayed a deficiency of iron accumulation. The macroscopic appearance of neoplasms was closely related to their cytoplasmic staining properties and cytochemical characteristics.
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PMID:Morphologic and cytochemical properties of mouse liver neoplasms induced by diethylnitrosamine and promoted by 4,4'-dichlorodiphenyltrichloroethane, chlordane, or heptachlor. 242 23

The Solt-Farber protocol, in the absence of an initiating agent, was used to examine the precursor-product relationship between oval cells and hepatocytes in rat liver. The animals were administered 2-acetylaminofluorene (AAF) by gavage for 2 wk combined with partial hepatectomy 1 wk after administering AAF Two dose levels of AAF were used: 9- and 21-mg total dose for animals in Groups I and II, respectively. [3H]Thymidine was administered i.p. to one-half of the animals at Day 6 post-partial hepatectomy. Animals were sacrificed 7, 9, 11, and 13 days after surgery. Only oval cells became labeled on Day 7 in both groups. On Day 9 both labeled oval cells and labeled basophilic hepatocytes were present in Group I, whereas in Group II only oval cells remained labeled. On Days 11 and 13 both oval cells and basophilic hepatocytes were labeled in both groups. The total amount of radioactivity in Group II livers remained the same on Day 9 when only labeled oval cells were present and on Days 11 and 13 when both labeled oval cells and labeled basophilic hepatocytes were present. The calculated half-life for basophilic hepatocytes was about 50 h. The differentiation of oval cells into basophilic hepatocytes was delayed in Group II as compared to Group I, and the higher dose of AAF also induced the formation of both intestinal metaplasia and bile duct formation. In situ hybridization with an alpha-fetoprotein probe showed a strong expression in groups of typical oval cells and in cells arranged in duct-like structures. In addition a transient expression of AFP was also observed in the areas of basophilic hepatocytes 9 to 11 days after partial hepatectomy. Administration of AAF decreased the level of albumin mRNA in preexisting hepatocytes and caused a significant decrease of serum albumin. In contrast, oval cells showed a strong albumin expression, and basophilic hepatocytes formed islands of albumin-expressing cells. Oval cells and the foci of early basophilic hepatocytes lacked glucose-6-phosphatase activity. At Day 13 significant numbers of basophilic hepatocytes were positive for glucose-6-phosphatase. Oval cells were strongly gamma-glutamyltranspeptidase positive, whereas the foci of basophilic hepatocytes were negative for gamma-glutamyltranspeptidase. Only occasionally were transiently gamma-glutamyltranspeptidase-positive hepatocytes observed in basophilic foci. In summary our data indicate that oval cells can differentiate to hepatocytes and may have an important physiological function as a source of major serum proteins when hepatocytes are unable to synthesize these proteins.
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PMID:In vivo differentiation of rat liver oval cells into hepatocytes. 246 57


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