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:2.6.1.1 (aspartate aminotransferase)
21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extract of Salvia Miltiorrhiza (SM) has been widely used in traditional Chinese medicine for treating liver diseases. Recent experimental evidence indicates that it has anti-tumor potential. In this study, the effect of SM on alfatoxin B1 (AFB1)-induced hepatocarcinogenesis was investigated in male Fischer 344 rats. AFB1 (40 microg/100 g body wt, by gavage) was administered once a week for 24 weeks. In SM treatment group, rats were given SM (0.25g/100g body wt, 5 days/week by gavage) for a total of 28 weeks, including 4 weeks before and 24 weeks during AFB1 exposure. Results showed that the elevation of serum alanine aminotransferase and aspartate aminotransferase activities due to AFB1 dosing was almost completely abolished by the treatment of SM, indicating that SM could prevent AFB1-induced liver cell injury. It was further observed that SM substantially reduced glutathione S-transferase placenta form (GST-P) positive foci formation and GST-P mRNA expression caused by AFB1, which clearly suggests that SM is effective in preventing AFB1-induced hepatocarcinogenesis. Furthermore, the inhibition on AFB1 hepatocarcinigenesis was associated with a corresponding decrease in AFB1-DNA adducts formation as well as AFB1-induced oxidative DNA damage (8-hydroxydeoxyguanosine) in rat liver. Our results also indicate that the protective effect of SM might be mediated through dual mechanisms: (i) the enhancement of AFB1 detoxification pathway, especially the induction of GST-Yc2 mRNA expression, and (ii) the antioxidant property of SM.
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PMID:Protection of salvia miltiorrhiza against aflatoxin-B1-induced hepatocarcinogenesis in Fischer 344 rats dual mechanisms involved. 1144 22

Streptozotocin (STZ) has drawn attention as a potential source of oxidative stress, which induces genotoxicity. We investigated the effects of STZ on DNA damage in the liver and kidney, as well as the protective effects of antioxidants, by using the alkaline single-cell gel electrophoresis assay, and by measuring the ratio of 8-hydroxy-2'-deoxyguanosine (8-OHdG) to dG. A single intraperitoneal injection of STZ (150 mg/kg) increased serum levels of glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and blood urea nitrogen (BUN), and also caused DNA damage in the liver and kidney, which recovered slowly with time. Antioxidants,(ascorbic acid, trolox and probucol) prevented the STZ-induced elevation of DNA damage in the liver and kidney and inhibited the increase in serum levels of AST, ALT and BUN. Thus ascorbic acid, trolox, and probucol protected the mice against STZ-induced DNA damage that might contribute to the development of hepatic or renal disease.
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PMID:DNA damage and the effect of antioxidants in streptozotocin-treated mice. 1206 20

Methionine metabolism is regulated by folate, and both folate deficiency and abnormal hepatic methionine metabolism are recognized features of alcoholic liver disease (ALD). Previously, histological features of ALD were induced in castrated male micropigs fed diets containing ethanol at 40% of kilocalories for 12 months, whereas in male micropigs fed the same diets for 12 months abnormal methionine metabolism and hepatocellular apoptosis developed. Folate deficiency may promote the development of ALD by accentuating abnormal methionine metabolism. Intact male micropigs received eucaloric diets that were folate sufficient, folate deficient, or each containing 40% of kilocalories as ethanol for 14 weeks. Folate deficiency alone reduced hepatic folates by one half, and ethanol feeding alone reduced methionine synthase, S-adenosylmethionine (SAM), and glutathione (GSH) levels and elevated plasma malondialdehyde (MDA) levels. The combined regimen elevated plasma homocysteine, hepatic S-adenosylhomocysteine (SAH), urinary 8-hydroxy-2-deoxyguanosine (oxy(8)dG), an index of DNA oxidation, and serum aspartate aminotransferase (AST) levels. Terminal hepatic histopathologic characteristics included typical features of steatonecrosis and focal inflammation in pigs fed the combined diet, with no changes in the other groups. Hepatic SAM levels correlated with those of GSH, whereas urinary oxy(8)dG and plasma MDA levels correlated with the SAM:SAH ratio and to hepatic GSH. The results demonstrate the linkage of abnormal methionine metabolism to products of DNA and lipid oxidation and to liver injury. The finding of steatonecrosis and focal inflammation only in the combined diet group supports the suggestion that folate deficiency promotes and folate sufficiency protects against the early onset of methionine cycle-mediated ALD.
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PMID:Folate deficiency, methionine metabolism, and alcoholic liver disease. 1216 45

The role of reactive oxygen species in liver fibrogenesis is not yet clarified. The aim of this study was to investigate oxidative-stress-related changes in cirrhotic rats. Cirrhosis was induced by bile duct ligation in Sprague-Dawley rats. Plasma malondialdehyde (MDA), hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG), hepatic mitochondrial respiratory functions and gene transcripts were measured at 2 and 4 weeks after surgery in bile-duct-ligated (BDL) and sham-operated-operated rats. The results showed progressive increases in the levels of plasma MDA, hepatic 8-OHdG and procollagen I and III mRNA expression, and progressive impairment of hepatic mitochondrial respiratory function in BDL rats at 2 and 4 weeks after ligation compared with sham-operated rats. Moreover, at 4 weeks after ligation, BDL rats exhibited reduced plasma glutathione and vitamin E levels, impaired hepatic mitochondrial electron transport enzyme activities and oxidative phosphorylation function. In addition, hepatic mRNA expression of transforming growth factor-beta1 was increased. Hepatomegaly, abnormal plasma alanine transaminase and aspartate transaminase levels, and portal hypertension were noted in BDL rats. Our results suggest that bile duct ligation in the rat induces mitochondrial dysfunction and biochemical and molecular changes related to oxidative stress in the liver.
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PMID:Oxidative-stress-related changes in the livers of bile-duct-ligated rats. 1259 53

We carried out this experiment to evaluate the relationship between isoforms of cytochrome P450 (P450) and liver injury in lipopolysaccharide (LPS)-induced endotoxemic rats. Male rats were intraperitoneally administered phenobarbital (PB), a P450 inducer, for 3 days, and 1 day later, they were intravenously given LPS. PB significantly increased P450 levels (200% of control levels) and the activities (300-400% of control) of the specific isoforms (CYP), CYP3A2 and CYP2B1, in male rats. Plasma AST and ALT increased slightly more in PB-treated rats than in PB-nontreated (control) rats with LPS treatment. Furthermore, either troleandomycin or ketoconazole, specific CYP3A inhibitors, significantly inhibited LPS-induced liver injury in control and PB-treated male rats. To evaluate the oxidative stress in LPS-treated rats, in situ superoxide radical detection using dihydroethidium (DHE), hydroxy-2-nonenal (HNE)-modified proteins in liver microsomes and 8-hydroxydeoxyguanosine (8-OHdG) in liver nuclei were measured in control and PB-treated rats. DHE signal intensity, levels of HNE-modified proteins, and 8-OHdG increased significantly in PB-treated rats. LPS further increased DHE intensity, HNE-modified proteins, and 8-OHdG levels in normal and PB-treated groups. CYP3A inhibitors also inhibited the increases in these items. Our results indicate that the induction or preservation of CYP isoforms further promotes LPS-induced liver injury through mechanisms related to oxidative stress. In particular, CYP3A2 of P450 isoforms made an important contribution to this LPS-induced liver injury.
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PMID:CYP3A induction aggravates endotoxemic liver injury via reactive oxygen species in male rats. 1528 27

Our goal was to elucidate roles of Nrf2 in in vivo defense against pentachlorophenol (PCP), an environmental pollutant and hepatocarcinogen in mice. We examined oxidative stress and cell proliferation, along with other hepatotoxicological parameters, in the livers of nrf2-deficient (wild:+/+, heterozygous:+/-, homozygous:-/-) animals fed PCP in their diet at doses of 0, 150, 300, 600, or 1200 ppm for 4 weeks. For measurement of methoxyresorufin-O-demethylase (CYP 1A2), NAD(P):quinone oxidoreductase 1 (NQO1), and UDP-glucuronosyltransferase (UDP-GT), an additional study was performed with all but the 150-ppm dose. Significant elevation of 8-hydroxydeoxyguanosine (8-OH-dG) levels in the liver DNA was observed only in -/- mice treated with PCP at 1200 ppm. Levels of thiobarbituric-acid-reactive substances (TBARS) were also raised significantly compared to those of the relevant +/+ mice. Bromodeoxyuridine labeling indices (BrdU-LIs) of hepatocytes in -/- mice were significantly higher at all doses than those in the relevant +/+ mice. Relative liver weights were unchanged in mice lacking Nrf2, whereas liver weight in +/+ and +/- mice was increased. Significant elevations of serum ALP activity, but not ALT and AST activity, occurred at 600 ppm and above in -/- mice compared to the relevant +/+ mice. Histopathologically, centrilobular hepatocyte necrosis was severe in the -/- mice that received 600 ppm. Although CYP 1A2 activity was elevated in all treated mice, increases in NQO1 levels and UDP-GT activities did not occur only in -/- mice. These data suggest that Nrf2 plays a key role in prevention of PCP-induced oxidative stress and cell proliferation.
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PMID:A crucial role of Nrf2 in in vivo defense against oxidative damage by an environmental pollutant, pentachlorophenol. 1635 18

Using the urinary 8-hydroxydeoxyguanosine (8-OHdG) concentration, effects of participation in a two-day ultramarathon race period on oxidative DNA damage were investigated in Japanese nonprofessional runners. Before the first day (baseline), after the first day (mid-race) of 40-km running, and after the second day (post-race) of 90 km running, biomaterials were successfully sampled from 95 participants (males, 79; females, 16) who completed the full race. We analyzed urine for 8-OHdG and blood for aspartate aminotransferase (AST), creatine phosphokinase (CPK) and myoglobin, and evaluated fluctuation in the values at three sampling time points. Adjusted baseline urinary 8-OHdG levels (microg/g creatinine) (mean +/- standard deviation) showed no significant differences between males and females, at 2.85 +/- 1.17 and 3.04 +/- 1.56, respectively. In males, mid-race urinary 8-OHdG levels rose to 3.29 +/- 1.15 (p < 0.01), but then returned to 2.73 +/- 1.16 at the post-race time point (p < 0.01). In females, a similar increase to 3.32 +/- 1.47 and subsequent decline to 2.80 +/- 1.47 were noted. In contrast, AST, CPK and myoglobin were increased at both mid- and post-time points and particularly the latter, independent of the sex. Extreme prolonged exercise in a two-day ultramarathon race period causes oxidative DNA damage but antioxidant repair systems are apparently induced to protect against oxidative DNA stress with physical exercise.
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PMID:Changes of urinary 8-hydroxydeoxyguanosine levels during a two-day ultramarathon race period in Japanese non-professional runners. 1761 24

The association between aflatoxin B1 (AFB1) exposure and oxidative stress was extensively examined in 84 adolescents from an area at high risk for hepatocellular carcinoma in China. Plasma level of aflatoxin B1-albumin adducts (AAAs) was associated with AFB1 excretion in urine (r = 0.394, P < 0.001). Urinary AFB1 was also associated with both the urinary excretion of 8-hydroxydeoxyguanosine (8-OHdG) (r > or = 0.479, P < 0.001) and 8-OHdG and hOGG1 levels in peripheral leukocytes (r > or = 0.308, P < or = 0.005). Similarly, AAA was significantly associated with both the urinary excretion of 8-OHdG (r > or = 0.259, P < or = 0.018) and the 8-OHdG and hOGG1 levels in peripheral leukocytes (r > or = 0.313, P < or = 0.004). In addition, urinary 8-OHdG was correlated with both the level of DNA 8-OHdG (r > or = 0.24, P < or = 0.05) and the expression of hOGG1 in peripheral leukocytes (r > or = 0.429, P < 0.001). Protein carbonyl content (PCC) level was significantly associated with not only the level of DNA 8-OHdG (r > or = 0.366, P < 0.001) and the urinary 8-OHdG (r > or = 0.258, P < or = 0.018) but also the expression of hOGG1 in peripheral leukocytes (r = 0.485, P < 0.001). A significant but weak association was found between high-performance liquid chromatograph-electrochemical detection (HPLC-ECD) and enzyme-linked immunosorbent assay (ELISA) for urinary 8-OHdG (r = 0.334, P = 0.002) and between HPLC-ECD and flow cytometry assays for 8-OHdG in leucocytes (r = 0.395, P < 0.001). Significant associations were observed between AAA and PCC and liver function indices (alanine aminotransferase and aspartate aminotransferase). These findings suggest significant contribution from AFB1 exposure to oxidative stress and subsequent repair among adolescents that may impose substantial risk for hepatocarcinogenesis in adulthood in this region.
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PMID:Evaluation of oxidative stress in a group of adolescents exposed to a high level of aflatoxin B1--a multi-center and multi-biomarker study. 1772 71

Oxidative stress due to iron deposition in hepatocytes or Kupffer cells contributes to the initiation and perpetuation of liver injury. The aim of this study was to clarify the association between dietary iron and liver injuries in rats. Liver injury was initiated by the administration of thioacetamide or ligation of the common bile duct in rats fed a control diet (CD) or iron-deficient diet (ID). In the acute liver injury model induced by thioacetamide, serum levels of aspartate aminotransferase and alanine aminotransferase, as well as hepatic levels of lipid peroxide and 4-hydroxynonenal, were significantly decreased in the ID group. The expression of 8-hydroxydeoxyguanosine and terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling positivity showed a similar tendency. The expression of interleukin-1beta and monocyte chemotactic protein-1 mRNA was suppressed in the ID group. In liver fibrosis induced by an 8-wk thioacetamide administration, ID suppressed collagen deposition and smooth muscle alpha-actin expression. The expressions of collagen 1A2, transforming growth factor beta, and platelet-derived growth factor receptor beta mRNA were all significantly decreased in the ID group. Liver fibrosis was additionally suppressed in the bile-duct ligation model by ID. In culture experiments, deferoxamine attenuated the activation process of rat hepatic stellate cells, a dominant producer of collagen in the liver. In conclusion, reduced dietary iron is considered to be beneficial in improving acute and chronic liver injuries by reducing oxidative stress. The results obtained in this study support the clinical usefulness of an iron-reduced diet for the improvement of liver disorders induced by chronic hepatitis C and alcoholic/nonalcoholic steatohepatitis.
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PMID:Attenuation of acute and chronic liver injury in rats by iron-deficient diet. 1803 66

Hepatic ischaemia-reperfusion injury is a serious problem that occurs during various surgical operations such as liver transplantation, surgical revascularization, and partial organ resection. Different pharmacological agents have been used for the protection of organ function and for extending the tolerable ischaemic interval after the ischaemic insult. We aimed to determine the presence of 8-hydroxydeoxyguanosine (8-OHdG) in the DNA from liver undergoing ischaemia-reperfusion, and also to evaluate the protective effects of N-acetylcysteine (NAC) and EGb761 (Ginkgo biloba extract) against hepatic oxidative DNA damage. A total of 40 rats were divided into four groups of 10 animals each (sham-operation group, control group, NAC group, and EGb761 group). Oxidative damage to DNA was evaluated by measuring the increase in 8-OHdG formation in liver tissue and also the effects of NAC and EGb761 pretreatment. Hepatic ischaemia for 90 min followed by reperfusion caused a marked increase in tissue levels of 8-OHdG, thiobarbituric acid-reactive substance, serum ALT, AST and LDH activities compared to sham-operated group. Pretreatment with both NAC and EGb761 clearly diminished 8-OHdG formation and lipid peroxidation. These findings suggest that antioxidant molecules such as NAC and EGb761 may be useful in preventing postischaemic reperfusion injury in hepatic tissue.
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PMID:Protective effects of N-acetylcysteine and Ginkgo biloba extract on ischaemia-reperfusion-induced hepatic DNA damage in rats. 1881 May 89


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