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)

Formation of the N-(deoxyguanosin-8-yl)-aminofluorene adduct was studied in enzyme-altered foci induced by four different liver carcinogenesis models. Foci were detected and scored for enzyme phenotype by a computer-aided image overlay technique. Localization of the enzymes gamma-glutamyl transpeptidase, canalicular ATPase and glucose-6-phosphatase was performed by enzyme histochemistry, allowing identification of foci of seven different phenotypes. Patterns of foci obtained by image overlay were compared to in situ 2-acetylaminofluorene--DNA adduct distribution obtained by immunofluorescence. Foci were induced by the following models: (1) chronic feeding of 0.02% 2-acetylaminofluorene (2-AAF) for 8 weeks; (2) intubation of diethylnitrosamine (DEN) (10 mg/kg) 24 h after a 70% partial hepatectomy (PH), followed 8 weeks later by a diet containing 0.05% phenobarbital for 9 months; (3) intubation of DEN (10 mg/kg) 24 h after PH, followed by a diet containing 0.01% ciprofibrate for 5 months, and after an additional 4 months a diet containing 0.05% phenobarbital for 2 months; (4) maintenance for 7.5, 16.5 or 19.5 months after transplantation of DEN/2-AAF/PH ('Solt-Farber' protocol) donor liver cells into host rats receiving a brief 2-AAF/PH selective regimen then no further treatment until sacrifice. To test the capacity of both foci and morphologically normal livers to form DNA adducts, the animals in models 2-4 received a diet containing 0.02% 2-AAF for 5 or 6 days before sacrifice. In all of the enzyme-altered foci identified in models 1-3 there were no DNA adducts visible by immunofluorescence. Scattered groups of positive cells were occasionally seen in the otherwise dark foci induced by model 4. For technical reasons some enzyme-altered foci were not identifiable on the fluorescence-stained slides. In liver serial sections from rats in models 1-4, there were 75, 304, 125 and 68 enzyme-altered foci of seven different phenotypes which were identified as AF-DNA negative. In models 1 and 4 there were some additional adduct-negative foci not associated with any of the seven identified focus phenotypes. These studies demonstrate that loss of the ability to form DNA adducts in hepatic enzyme-altered foci is a common and very early biochemical adaptation to xenobiotic exposure in different hepatocarcinogenesis models. This adaptation also is retained by the majority of foci in later stages of hepatocarcinogenesis.
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PMID:Lack of acetylaminofluorene--DNA adduct formation in enzyme-altered foci of rat liver. 289 93

A rapid increase in the fraction of small liver cells was observed in the liver of rats during the early stage of hepatocarcinogenesis by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). The change in cell population was represented by the decrease in glucose-6-phosphatase activity and by the increase in number of gamma-glutamyltranspeptidase-positive cells. When DNA synthesis of liver cells from rats fed 3'-Me-DAB was measured by autoradiography in primary culture, it began to increase 2 weeks after the start of the carcinogen feeding, reaching a plateau level after 3 weeks. Liver cells from rats fed 3'-Me-DAB for 2 weeks or over demonstrated a remarkable resistance to the cytotoxic effect of the carcinogen (0.24 mM) in primary culture. Furthermore, liver cells from rats fed 3'-Me-DAB for 3 weeks or over proliferated in the presence of the carcinogen in primary culture. When liver cells from 3'-Me-DAB-fed and control rats were transplanted into syngeneic rat spleens, the former cells proliferated more vigorously than did the latter. The growth potential of liver cells from 3'-Me-DAB-fed rats tended to be enhanced with time in the carcinogen feeding. Hepatocellular carcinomas developed in the host spleens implanted with liver cells from a rat fed 3'-Me-DAB for 8 weeks. As described above, liver cells from rats fed 3'-Me-DAB demonstrated much greater proliferative ability than normal control cells in vivo and in vitro.
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PMID:In vivo and in vitro test for growth potential of liver cells from rats during early stage of hepatocarcinogenesis by 3'-methyl-4-dimethylaminoazobenzene. 292 Dec 69

Sonic disrupted mitoplasts from 3-methylcholanthrene (MCA) treated rats can catalyze the formation of benzo(a)pyrene (BaP) adducts with calf thymus DNA in the presence of an NADPH generating system. The mitoplasts used in this study contained less than 1% microsomal marker enzymes: rotenone insensitive NADPH cytochrome c reductase and glucose-6-phosphatase. The rates of BaP metabolism and DNA adduct formation per nanomole cytochrome P-450 were different for MCA induced mitochondrial and microsomal enzymes. The major B(a)P DNA adducts formed in incubations with lysed mitoplasts were derived from reaction of 9-OH-B(a)P-4,5 oxide with deoxyguanosine. The results suggest a potential role of mitochondrial monooxygenase activity in the covalent binding of B(a)P to mitochondrial DNA.
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PMID:Formation of benzo(alpha)pyrene metabolites and DNA adducts catalyzed by a rat liver mitochondrial monooxygenase system. 299 32

Cultured hepatocytes from adult Fischer 344 rats were transformed by virion or cloned simian virus 40 (SV40) DNA using the calcium phosphate method. Transformation by SV40 occurred in either serum-supplemented medium or chemically defined medium (CDM). The frequency was greatest in serum-supplemented medium but transformants did not remain differentiated. In contrast, SV40 transformants developed less frequently in CDM, but retained differentiated functions. The frequency of transformation was enhanced by treatments that stimulated cell proliferation, in particular supplementing CDM with epidermal growth factor. Hepatocytes transformed in CDM were epithelial in morphology, secreted albumin, transferrin, hemopexin, and expressed the enzyme glucose-6-phosphatase, all characteristics of normal liver. Transformants did not produce detectable levels of alpha-fetoprotein, a marker of fetal or abnormal liver. We conclude that (a) hepatocytes can be transformed by transfection with SV40 DNA; (b) the frequency of transformation is enhanced by stimulating DNA synthesis; and (c) the transformed cells retain specific functions of normal hepatocytes in situ. Using this system it will be possible to study transformation of hepatocytes by viral and cellular oncogenes and to determine their effects on hepatocellular differentiation.
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PMID:Transformation of rat hepatocytes by transfection with simian virus 40 DNA to yield proliferating differentiated cells. 301 81

The effects of 8-(2-dimethylaminoethyl)-3-oxo-4-phenyl-1-thia-4,8-diazaspiro [4, 5] decane dihydrochloride monohydrate (Y-8845) on carbon tetrachloride (CCl4)-induced liver injury were investigated in rats. CCl4-induced attenuation of the plasma cyclic AMP (cAMP) response to glucagon stimulation was significantly prevented by pretreatment with Y-8845. Y-8845 also effectively suppressed the increases in the activities of serum transaminases as well as the decreases in microsomal glucose-6-phosphatase activity and microsomal cytochrome P-450 concentrations induced by CCl4. In rats at 72 hr after CCl4 administration, the plasma cAMP response to glucagon, microsomal glucose-6-phosphatase activity and P-450 concentration were all below the control level. Y-8845 treatment after CCl4 administration rectified these reductions to nearly normal levels. Furthermore, Y-8845 stimulated DNA synthesis during liver regeneration after CCl4 intoxication. These results demonstrate that Y-8845 has a protective effect against CCl4-induced injury in the liver and a stimulating effect on the recovery of the damaged liver.
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PMID:Effects of 8-(2-dimethylaminoethyl)-3-oxo-4-phenyl-1-thia-4,8-diazaspiro [4,5] decane dihydrochloride monohydrate (Y-8845) on carbon tetrachloride-induced liver injury. 301 90

Spermatogenically active testes of rat challenged by 100 mg/kg body weight of p- Chlorophenylalanine for 45 days displayed marked and drastic changes in the seminiferous epithelium. Degenerative changes followed by immense necrosis of germ cells lead to complete breakdown of seminiferous tubules. Leydig cells, however, remained unaffected histologically in the treated animals. Among the accessory sex organs, epididymis alone showed a marked decrease in its weight. A biochemical study in the drug treated rats revealed a significant accumulation of glycogen in the testes accompanied by increase in the activities of enzymes like the succinic dehydrogenase, glucose-6-phosphatase, ATP-ase and acid phosphatases. However, a marked decrease was noticed in the activities of enzymes like alkaline phosphatase, phosphohexose isomerase and lactate dehydrogenase. No significant change was found in the protein, DNA and RNA concentrations in the drug treated testes. The histological and biochemical changes induced in the testes by p-CPA suggest the deleterious effect of the drug on the seminiferous tubules of the testes.
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PMID:Effect of para-chlorophenylalanine on male rats: histopathological and biochemical changes in the testes. 303 Sep 34

To investigate the molecular basis of dosage compensation in Drosophila, a recombinant lambda phage containing the Drosophila melanogaster glucose-6-phosphatase dehydrogenase (G6PD) gene was isolated by differential screening of a Drosophila genomic lambda library with poly(A)+RNA obtained from polyribosomes enriched for or depleted of G6PD mRNA sequences. Of 44 000 plaques screened, a single phage, lambda DmG21, showed hybridization with the enriched poly(A)+RNA but not the depleted one. Confirmation that the Drosophila DNA fragment cloned in lambda DmG21 contains the G6PD gene sequence is based on the following observations. lambda DmG21 DNA shows hybridization only to the 18D region of the salivary gland X-chromosome, which is the known cytological locus for the G6PD gene. In vitro translation of the poly(A)+mRNA selected by hybridization to lambda DmG21 DNA sequences shows a polypeptide product of apparent Mr 55 000, identical to that of the monomeric unit of G6PD. When the putative coding sequence of G6PD is cloned into the expression vector lambda gt11, recombinant plaques are recognized by anti-G6PD immunoglobulin. A transcriptional map of the G6PD gene shows that it is divided into two exons, 0.9 kb (exon I) and 1.8 kb (exon II) long, which are separated by a 2.4-kb intron. The G6PD mRNA is 2.0 kb in length and the steady-state level of the mRNA is similar in both sexes. Measurement of the copy number of the G6PD gene in males and females shows the gene to be present once per X-chromosome in both sexes. No amplification of the gene sequence was observed in males. These results are, therefore, in agreement with the previous suggestion that dosage compensation is the result of enhanced transcription of X-linked genes in males.
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PMID:Isolation and characterization of the glucose-6-phosphate dehydrogenase gene of Drosophila melanogaster. 316 84

Compound LY171883 caused dose-related and reversible hepatomegaly in male Fischer 344 rats. Histological examination revealed hepatocellular hypertrophy with no other evidence of liver disease. There were only minor changes in serum glucose, total bilirubin, alkaline phosphatase, and alanine transaminase which were generally unrelated to dose and dissociable from the hepatomegaly. Total liver DNA increased but the DNA concentration decreased, indicating that liver growth involved a combination of hypertrophy and hyperplasia. Total liver protein and RNA increased. Hepatic mitochondrial protein content increased but cytochrome oxidase activity was not changed. There were minor changes in mitochondrial respiratory parameters; however, all the values were in the normal range and there was no indication of mitochondrial toxicity. Microsomal protein, drug-metabolizing activity, and cytochrome P-450 increased, but glucose-6-phosphatase activity was not changed. The induction of drug-metabolizing enzymes and absence of toxicity were evidence that the hepatomegaly was an adaptation to an increased functional load in the liver. An increase in catalase activity suggested that the response may have also involved peroxisomes. In addition to rats, LY171883 administration caused hepatomegaly in mice and hamsters at daily exposures exceeding 100 mg/kg. The response was not observed in guinea pigs, beagle dogs, or rhesus monkeys given maximum tolerated doses, indicating LY171883-induced hepatomegaly is not a response common to all species. The doses required to elicit hepatomegaly greatly exceeded doses that produce pharmacological efficacy in animals and those that are expected to be used clinically. Since humans will not receive doses comparable to those given rodents, and considering that the primate species tested did not experience hepatomegaly, it is unlikely that the effect observed in rodents can be extrapolated to humans.
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PMID:Characterization of liver enlargement induced by compound LY171883 in rats. 384 Jan 8

Two carcinogenic aromatic amines with different organotropism were tested for syncarcinogenic effects in rat liver in an initiation-promotion experiment. Trans-4-acetylaminostilbene (AAS) and 2-acetylaminofluorene (AAF) were administered as initiators in four doses each either alone or sequentially combined in both orders. The promotion phase was started by partial hepatectomy and continued by adding phenobarbital (250 p.p.m.) to the drinking water for 26 weeks. The number/cm2 of tissue section and average size of hyperplastic foci, glucose-6-phosphatase-deficient and gamma-glutamyl-transpeptidase-positive foci were determined and a total area of lesions calculated during the promotion phase after 18 and 31 weeks, and in the post-promotion phase after 42 and 47 weeks. The synergistic effects of AAS and AAF were clearly more than additive if compared with the sum of the effects exerted by each compound individually. The sequence in which both initiators were administered remarkably influenced the development of lesions. They developed more rapidly and persisted longer in the post-promotion phase when AAS was administered first and AAF second. In the final stage, enzyme altered foci increased in the livers of both combination groups, but to a greater extent in the AAS-AAF group. It is concluded that the two arylamides damage DNA independently. In addition, however, the results suggest that AAS acts predominantly as an initiator, and AAF as a weak initiator and a strong promoter in what is considered the initiation phase of this experiment.
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PMID:Syncarcinogenic effects on the initiation of rat liver tumors by trans-4-acetylaminostilbene and 2-acetylaminofluorene. 402 33

The endogenous synthesis of cholesterol in hepatocyte nodules, induced in male Wistar rats, by a single dose of the hepatocarcinogen diethylnitrosamine followed by a selection procedure, was investigated and was compared with that in surrounding and control tissue. In addition, the activity of enzymes related to carbohydrate metabolism (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glucose-6-phosphatase and pyruvate kinase), was measured. Hepatocyte nodules showed a striking increase in their capacity for synthesizing cholesterol, in comparison to surrounding and control tissues, and an enhancement in the activity of the pentose phosphate pathway, as indicated by increased activity of glucose-6-phosphate dehydrogenase and of 6-phosphogluconate dehydrogenase, and a concomitant decrease of glucose-6-phosphatase. The stimulation of cholesterol synthesis and of the pentose phosphate pathway was associated with increased incorporation of labelled thymidine into DNA. These data indicate that, among other metabolic disturbances, enhancement of cholesterol synthesis and of the pentose phosphate pathway, is accompanied by an increased proliferative capacity of hepatocyte nodules.
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PMID:Enhancement of cholesterol synthesis and pentose phosphate pathway activity in proliferating hepatocyte nodules. 402 34


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