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)

Pure rat liver heavy mitochondrial fractions, in which the absence of significant microsomal contamination was confirmed by electron microscopy and by the lack of glucose-6-phosphatase activity, were used to demonstrate the effect of paraquat on mitochondrial ultrastructure in the presence of external NADH. Starved mitochondria (orthodox conformation) did not show O2 uptake or structural injury from either paraquat alone or NADH alone. Marked O2 uptake and structural breakage occurred only when paraquat and NADH were added in combination. These alterations were resistant to rotenone and malate plus glutamate or NADPH could not substitute for NADH. Paraquat was reduced anaerobically by the mitochondria in the presence of NADH, but not of NADPH. The addition of superoxide dismutase, ferricytochrome c or p-benzoquinone protected against the breakage of mitochondria caused by paraquat plus NADH. These results demonstrate that mitochondria may produce paraquat radicals in the presence of extramitochondrial NADH and thus generate superoxide anion radicals, resulting in structural injury to the mitochondria, by mechanisms that may involve the mitochondrial outer membrane rather than the electron transfer chain. These mitochondrial mechanisms in paraquat toxicity seemed to be more probable in vivo than are microsomal mechanisms; the latter are postulated to function in detoxication because phenobarbital diminished paraquat toxicity and SKF 525-A or cobaltous ions enhanced the toxicity.
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PMID:Paraquat damage of rat liver mitochondria by superoxide production depends on extramitochondrial NADH. 134 81

Extreme copper deficiency has been shown to enhance CCl4-induced injury in rats. CCl4 hepatotoxicity was studied in rats with copper deficiency moderated by limiting deficiency periods to 5 or 6 weeks, using minimally adequate dietary zinc and including a marginal copper diet. Also, housing some rats in groups of six, rather than individually, was found to moderate the effects of low copper intake. Weanling male rats were fed copper at either 6, 2, or 0.2 mg/kg diet (adequate, marginal, deficient). Copper-zinc superoxide dismutase activity levels for singly and group-housed marginal rats were 80% and 93%, respectively, of adequate values. Values for deficient rats were 35% (singles) and 47% (group). In singly housed rats, a CCl4 dose of 400 microliters/kg intraperitoneally increased serum sorbitol dehydrogenase activities, indicators of cell membrane hepatotoxicity, in inverse proportion to dietary copper. A lower dose (100 microliters/kg) also produced smaller sorbitol dehydrogenase increases in adequate rats compared with deficients, but produced lowest increases in the marginals. The latter pattern also occurred in group-housed rats given the higher CCl4 dose, but the difference for adequate and marginal rats was not significant. The higher CCl4 dose, in singly housed rats, decreased liver glucose-6-phosphatase activities independently of copper intake. These activities are inversely proportional to microsomal lipid damage. In conclusion, moderate copper deficiency enhanced CCl4 hepatotoxicity, but the effect depended on injury criteria, CCl4 dose, and actual copper status as assessed by copper-zinc superoxide dismutase activities.
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PMID:Effects of moderate copper deficiency on carbon tetrachloride-induced hepatotoxicity in rats. 185 May 23

Dietary restriction extends maximum life span in rodents by unknown mechanisms. We compared livers from 12- and 24-mo-old mice fed control (C, approximately 95 kcal/wk) or restricted (R, approximately 55 kcal/wk) amounts of diet since 3 wk of age. We hypothesized that dietary restriction might alter the activity levels of enzymes with possible relevance to aging processes. The enzymes included several xenobiotic metabolizers, radical scavengers (catalase, superoxide dismutase, glutathione peroxidase), superoxide sources (xanthine oxidase, peroxisomal beta-oxidation of palmitoyl-CoA) and glucose-6-phosphatase. Lipid peroxidation (LP) was also measured. Comparing 12- and 24-mo-old mice, the strongest diet or age effect was an increased catalase activity for group R (42% higher at 12 mo, 64% at 24 mo). LP was clearly lower in group R at 12 mo (a 30% decrease) and somewhat lower (13%) at 24 mo than in group C. Similarly, in 12-mo-old C and R mice injected with either the P-450 inducer beta-naphthoflavone (beta-NF in corn oil) or with corn oil alone. R mice showed higher catalase activity (40-44%) and lower LP (43-46%) in both beta-NF-injected and vehicle-injected groups. These data suggest that if free radical damage is involved in aging, it may be a particular kind of damage, that is, that in part prevented by a selective increase in catalase activity.
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PMID:Influences of dietary restriction and age on liver enzyme activities and lipid peroxidation in mice. 303 Dec 54

1. The NADPH-dependent lipid peroxidation process was studied with microsomes and also the effects of addition of superoxide dismutase, catalase and thiourea. Only catalase and thiourea were able to inhibit lipid peroxidation. It seems that the initiating radical is the OH. radical formed by the Fenton reaction. 2. During lipid peroxidation glucose-6-phosphatase is inactivated, whilst the microsomal enzyme palmitoyl-CoA hydrolase is practically not affected. Because glucose-6-phosphatase activity decreases during ageing and palmitoyl-CoA hydrolase does not, a possible relationship with the ageing process is thought to exist. 3. Chromolipids are formed by the NADPH-dependent lipid peroxidation. These chromolipids have the same excitation-emission spectra as described for lipofuscin. The formation of these chromolipids is blocked by the addition of catalase and thiourea. 4. High-molecular weight proteins are formed during the NADPH-dependent lipid peroxidation. This process can be associated with the inactivation of enzymes. Also polymerisation is prevented by catalase and thiourea.
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PMID:Lipid peroxidation of rat liver microsomes. 611 5

The anti-cancer efficacy of dietary beta-carotene (BC, 120 mg/kg diet, daily) was evaluated during diethylnitrosamine (DEN, 200 mg/kg body weight)-induced hepatocarcinogenesis in male Sprague-Dawley rats. BC treatment was carried out throughout the study, before initiation or selection/promotion phase of hepatocarcinogenesis in a defined experimental protocol. In red blood cells (RBC) and microsomal fractions from hepatic nodular and non-nodular surrounding parenchyma, the enzymatic lipid peroxidation increased significantly by more than 3-fold, 9- to 10-fold and 4- to 7-fold respectively 18 weeks following initiation by DEN as compared to normal control animals. RBC membrane protein damage was estimated by alanine release and was found to increase more than 5-fold in the same time period in DEN control rats. A decrease in hepatic cytosolic and microsomal glucose-6-phosphatase activities was observed, whereas the activities of the oxygen-derived free-radical scavenger enzymes, like cytosolic catalase and superoxide dismutase, were shown to increase significantly at the same time point. However, BC exposure in the different phases to hepatocarcinogenesis substantially changed all the above parameters in limiting the action of DEN. Results showed that the most significant beneficial effect of BC during hepatocarcinogenesis was exerted mainly in long term continuous and/or the initiation phase of carcinogenicity, rather than in the selection/promotion phase. Moreover, the volumetric and numerical densities of the preneoplastic lesions were all appreciably reduced by exposure to BC. We conclude that long term intake of BC could reduce cancer risk by preventing hepatic lipid peroxidation and RBC membrane protein damage due to its antioxidant actions.
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PMID:Beta-carotene prevents lipid peroxidation and red blood cell membrane protein damage in experimental hepatocarcinogenesis. 859 Apr 36

To investigate the pathogenesis of retina lesions caused by intraocular pressure elevation, activities and distribution of enzymes in retina including lactic dehydrogenase (LDH), succinate dehydrogenase (SDH), adenosinetriphosphatase (AT-Pase), acid phosphatase (ACP), cholinesterase (ChE), cytochrome oxidase (CCO), nucleotidase (5'-Nase) and glucose-6-phosphatase (G6Pase) were determined histochemically in 30 rabbits. It was found that 1) in the early stage of intraocular pressure elevation, the activities of LDH, SDH, ATPase, ACP, and ChE in retina were increased, while the activities of CCO, 5'-Nase decreased; 2) in the late stage of intraocular pressure elevation, the activities of all these enzymes but ACP, which showed a reduced activity, were close to the normal level; 3) in superoxide dismutase.(SOD-CCE) treated group, except the slight increase of LDH and G6Pase activities, the activities of the remaining enzymes were near to normal. Our results suggest that the various histochemical changes in retina induced by intraocular pressure elevation were compensatory in the early stage and were beneficial to the supply of energy needed in retinal tissue and cellular metabolism; while in the late stage, the lesion of retina cells developed due to decompensation. SOD-CCE could alleviate the retinal lesions caused by intraocular pressure elevation, and can be used as auxiliary drug for the treatment of intraocular pressure elevation.
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PMID:Enzymatic histochemistry of retina with experimental intraocular pressure elevation in rabbits. 873 48

Cellular redox status and membrane protein activities were analyzed in kidneys from rats with ischemic acute renal failure (ARF). ARF was induced by clamping the left renal artery for 50 min. A parallel group of control animals was processed. In the ischemic group urea plasma levels were statistically increased as compared with the control group. Studies employing whole kidney homogenates revealed that ischemia produces an increment in lipid peroxidation levels and a reduction in glutathione concentration and in superoxide dismutase and glutathione peroxidase activities. Since lipid peroxidation may alter the function of membrane proteins we determined succinate cytochrome c reductase (SuccR), sodium-potassium ATPase (Na-K-ATPase), glucose-6-phosphatase (G-6-Pase) and alkaline phosphatase (ALP) activities in whole renal homogenates. Only G-6-Pase and ALP activities were modified by ischemia. Since ALP is a brush border membrane (BBM) enzyme and BBM is one of the main target structures in ARF, we assessed some parameters of BBM functionality. ALP, gamma-glutamyl transferase (gamma-GT) and 5'-nucleotidase (5'-NT) showed diminished activities in BBM from ischemic kidneys. Ischemia also modified the Vmax of paraaminohippuric acid (PAH) uptake without altering Km. An increment of lipid peroxidation and membrane fluidity in BBM was observed after the treatment. Total membrane proteins and protein recoveries in BBM were similar in both experimental groups. Sialic acid and sulfhydryl levels were similar in BBM from ischemic kidney and control ones. In summary, ARF induced by renal artery clamping for 50 min takes place with a significant increase in urea plasma levels. A decrease in the antioxidant defense system is detected. This induces lipid peroxidation in whole renal tissue, which may justify the diminished activities of some membrane enzymes such as G-6-Pase and ALP. A specific analysis of BBM function reveals a significant increment of lipid peroxidation which may be the cause of an increased membrane fluidity. This latter parameter might be, at least in part, responsible for the damaged function of apical ALP, 5'-NT, gamma-GT and PAH carrier.
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PMID:Impairment of cellular redox status and membrane protein activities in kidneys from rats with ischemic acute renal failure. 968 97

The effects of Ocimum sanctum leaf extract on the changes in the concentrations of serum triiodothyronine (T3), thyroxine (T4) and serum cholesterol; in the activities of hepatic glucose-6-phosphatase (G-6-P), superoxide dismutase (SOD) and catalase (CAT); hepatic lipid peroxidation (LPO) and on the changes in the weight of the sex organs were investigated. While the plant extract at the dose of 0.5 g kg-1 body wt. for 15 days significantly decreased serum T4 concentrations, hepatic LPO and G-6-P activity, the activities of endogenous antioxidant enzymes, SOD and CAT were increased by the drug. However, no marked changes were observed in serum T3 level, T3/T4 ratio and in the concentration of serum cholesterol. It appears that Ocimum sanctum leaf extract is antithyroidic as well as antioxidative in nature.
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PMID:Ocimum sanctum leaf extract in the regulation of thyroid function in the male mouse. 972 97

The importance of ashwagandha root extract in the regulation of thyroid function with special reference to type-I iodothyronine 5'-monodeiodinase activity in mice liver has been investigated. Although the root extract (1.4 g kg(-1)) administered daily for 20 days by gastric intubation increased serum 3,3',5-triiodothyronine (T3) and tetraiodothyronine (T4) concentrations and hepatic glucose-6-phosphatase activity, hepatic iodothyronine 5'-monodeiodinase activity did not change significantly. Furthermore, ashwagandha root extract significantly reduced hepatic lipid peroxidation, whereas the activity of antioxidant enzymes such as superoxide dismutase and catalase were increased. These findings reveal that the ashwagandha root extract stimulates thyroidal activity and also enhances the antiperoxidation of hepatic tissue.
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PMID:Changes in thyroid hormone concentrations after administration of ashwagandha root extract to adult male mice. 981 Nov 69

In this investigation we attempted to find out the hitherto unstudied adverse effects of neem (Azardirachta indica) leaf extract on the thyroid function of male mice. Neem leaf extract was orally administered in two different doses (40 mg and 100 mg kg(-1)day(-1)for 20 days). The extract exhibited differential effects. While the higher dose decreased serum tri-iodothyonine (T(3)) and increased serum thyroxine (T(4)) concentrations, no significant alterations of levels were observed in the lower dose group, indicating that the high concentrations of neem extract can be inhibitory to thyroid function, particularly in the conversion of T(4)to T(3), the major source of T(3)generation. A concomitant increase in hepatic lipid peroxidation (LPO) and a decrease in glucose-6-phosphatase (G-6-Pase) activity in the higher dosed group also indicated the adverse effect of neem extract despite an enhancement in the activities of two defensive enzymes, superoxide dismutase (SOD) and catalase (CAT). Thus, it appears that the higher concentration of neem extract may not be safe with respect to thyroid function and lipid peroxidation.
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PMID:How safe is neem extract with respect to thyroid function in male mice? 1070 65


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