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:2.6.1.2 (alanine aminotransferase)
26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Porphyria was induced in C57BL/10 mice with iron overload by a single oral dose (100 mg/kg) of hexachlorobenzene (HCB). Within 2 weeks hepatic uroporphyrinogen decarboxylase (EC 4.1.1.37) was inhibited, reaching a maximum (greater than 95%) at 6-8 weeks. There was no recovery by 14 weeks, despite a fall in liver HCB concentrations to only 6% of the day-3 value. The major rise in hepatic porphyrin levels occurred after 4 weeks and secondary inhibition of uroporphyrinogen synthase (EC 4.2.1.75) was inferred from the progressively greater proportion of uroporphyrin I present relative to the III isomer. Plasma alanine aminotransferase (EC 2.6.1.2) activity was also elevated. Although, in further studies, total microsomal cytochrome P-450 content and ethoxyphenoxazone de-ethylase activity reached a peak a few days after dosing and had declined significantly at the time of maximum inhibition of the decarboxylase, additional treatment of HCB-dosed mice with a cytochrome P1-450 inducer, beta-naphthoflavone, enhanced the inhibition, whereas piperonyl butoxide, an inhibitor of cytochrome P-450, partially protected. Uroporphyrinogen decarboxylase was not radiolabelled in vivo by [14C]HCB. There was no major difference in the ability to hydroxylate HCB between hepatic microsomes from induced C57BL/10 mice and those from the insensitive DBA/2 strain. By contrast, lipid peroxidation, in the presence of NADPH, was 8-fold greater in control C57BL/10 microsomes than in DBA/2 microsomes and was stimulated by iron treatment (although not by HCB). The results suggest that the inhibition of hepatic uroporphyrinogen decarboxylase is unlikely to be due to a direct effect of a metabolite of HCB but to another process requiring a specific cytochrome P-450 isoenzyme and an unknown iron species.
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PMID:Mechanistic studies of the inhibition of hepatic uroporphyrinogen decarboxylase in C57BL/10 mice by iron-hexachlorobenzene synergism. 380 Sep 66

The safety of pre-operative transcatheter arterial embolization (TAE), especially on the relation to hepatic regeneration following partial hepatectomy, was evaluated in rats. TAE was done through a catheter cannulated into hepatic artery under laparotomy. The remarkable elevation of S-GOT and S-GPT levels were demonstrated a day after TAE, which returned to normal on third post operative day. No influence of the difference of embolized materials was seen on the changes of transaminase levels. TAE severely decreased hepatic microsomal functional mass measured by [14C]-aminopyrine breath test (ABT) and the recovery of microsomal functional mass was shown on the 14th day after TAE. Histologically, recanalization could not be revealed in embolized arterioles even on the 21st day after TAE. But trabecular pattern of hepatic lobules was preserved after TAE. The serious inhibition of DNA synthesis of regenerating liver was demonstrated when TAE was performed within 14 days prior to partial hepatectomy (p less than 0.001-0.05). The period from TAE to partial hepatectomy had a influence on the survival rate after partial hepatectomy, and when appropriate interval was taken after TAE, the survival rate increased significantly (33%-50% in 24 hours interval and 88% in 14 days interval). In conclusion, preoperative TAE remarkably suppressed hepatic regeneration after partial hepatectomy, and appropriate time when suppressed hepatic functional mass, such as microsomal functional mass measured by ABT, returned to pre TAE value was required to perform hepatectomy in safety.
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PMID:[Effects of preoperative transcatheter arterial embolization (TAE) on the liver following partial hepatectomy in rats]. 382 17

Murine IFN(gamma) and human IFN(alpha)-AD:Bgl were compared over a limited dose range and after single and multiple dosing for their effect on male mouse liver oxidative and conjugative drug metabolizing enzymes. Both IFNs depressed the microsomal cytochrome P-450 concentration but did not alter cytosolic glutathione S-transferase nor microsomal UDP-glucuronosyltransferase activity. Both IFNs showed some slight hepatotoxicity (elevated serum ALT), alpha AD:Bgl more than gamma, especially after multiple dosing. While the IFNs did not produce significant increases in liver weight, they did increase the yield of microsomal protein. The increased endoplasmic reticulum may compensate for the decreased cytochrome P-450 concentration and so account for the lack of observed effect of the IFNs on hexobarbital sleep times in vivo. Overall, the minimal effects of murine gamma-IFN on the mouse liver were no different than those of human alpha AD:Bgl.
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PMID:Effect of murine gamma-interferon on the mouse liver and its drug-metabolizing enzymes: comparison with human hybrid alpha-interferon. 392 33

Weanling, male Sprague-Dawley rats given 10% ethanol in the drinking water and food ad lib. for up to 8 weeks consumed 17% of their calories as ethanol. The alanine aminotransferase (ALT), aspartate aminotransferase (AST), and liver histology by light microscopy were unaffected by this treatment. Similarly, hepatic microsomal NADPH-cytochrome c reductase, ethylmorphine N-demethylase and benzphetamine N-demethylase activities were also not affected by ethanol consumption. On the other hand, cytochrome P-450 content, aniline hydroxylase activity and acetaminophen metabolism as measured by both the cysteine conjugate and the [3H]acetaminophen covalently-bound to microsomal protein were increased significantly by ethanol consumption. The maximal effect was seen by 6 weeks. The 2- to 3-fold increase in aniline and acetaminophen metabolism, the absence of liver damage, and the similarity in weight gains and caloric intakes for controls and treated animals suggest that the rat on 10% ethanol in the drinking water is a reasonable model for studies of the effect of moderate alcohol consumption on specific biochemical pathways.
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PMID:Studies on the effect of chronic consumption of moderate amounts of ethanol on male rat hepatic microsomal drug-metabolizing activity. 393 44

Male Fischer 344 rats were exposed to halothane, enflurane or isoflurane vapour 20 p.p.m., or air, for up to 30 weeks. None of the anaesthetic agents led to hepatocellular necrosis. Exposure to halothane resulted in slight increases in serum alanine aminotransferase activity, an increase in the size of the liver, an increase in hepatic microsomal cytochrome P-450 content and a minimal amount of fatty change in the liver. None of these effects were observed during exposure to enflurane or isoflurane. Urinary fluoride excretion was increased during exposure to either enflurane or isoflurane. Using this increase as an index of anaesthetic biotransformation, we found that the extent of biotransformation of isoflurane was only slightly lower than that of enflurane.
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PMID:Effects of chronic inhalation of halothane, enflurane or isoflurane in rats. 396 17

Experiments were conducted to examine the role of zinc in the prevention of bromobenzene hepatoxicity in male rats. Bromobenzene (BB) (7.5 mmol/kg, ip) produced a marked hepatotoxicity as evidenced by increases in plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and a marked depression in hepatic glutathione (GSH) content 24 hr after administration. The administration of zinc (92 mumol Zn/kg, ip, at 48 and 24 hr prior to the bromobenzene) ameliorated the bromobenzene elevations in plasma AST (25%) and plasma ALT (50%) but did not alter the decreases in hepatic GSH. Following administration of [14C]BB, the radioactive label was distributed primarily in the cytosolic and lipid fractions derived from liver homogenates. Furthermore, the subcellular distribution of [14C]BB was not altered by zinc pretreatment. The extent of covalent binding of [14C]BB metabolites to hepatic tissue was significantly depressed in zinc-treated rats. Zinc induced the hepatic levels of metallothionein but [14C]BB did not bind to this sulfhydryl rich protein. Further experiments showed that zinc treatment depressed cytochrome P-450 content, the activity of NADPH cytochrome c reductase, and the metabolism of aniline, but not that of ethylmorphine. These studies suggest that the hepatoprotective effect of zinc against bromobenzene toxicity does not involve altered binding of the reactive toxic metabolite to glutathione or metallothionein, but it may be mediated by the inhibitory effect of zinc on the microsomal cytochrome P-450-dependent drug metabolizing system.
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PMID:Amelioration of bromobenzene hepatotoxicity in the male rat by zinc. 398

When male Sprague-Dawley rats were treated with sodium selenite (1 mg/kg, sc) 24 hr prior to or simultaneously with bromobenzene (2.5 mmol/kg, ip) and sacrificed 48 hr after the bromobenzene dose, increased levels of the activities of serum transaminases (serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) induced in the bromobenzene-treated rats were significantly reduced in the presence of selenium. However, no such reduction in the transaminases activities were observed when rats were either pretreated with selenite for 48 hr or pretreated with 0.1, 0.2, or 0.5 mg/kg of selenite. Although selenium alone had no effect on the hepatic microsomal drug metabolism, simultaneous treatment of selenite (1 mg/kg) with bromobenzene resulted only an increase in the activity of aniline hydroxylase after 48 hr as compared to that in the bromobenzene-treated group. When rats were given 2.5, 10, and 20 ppm of selenite in drinking water daily for 4 weeks prior to an ip injection of 2.5 mmol/kg of bromobenzene and were sacrificed 48 hr after bromobenzene administration, a reduction in the SGOT activities in all the pretreated groups and a reduction of SGPT activity in 20 ppm selenite-treated group were observed when compared with those in the bromobenzene-treated groups. A dose-dependent increase in hepatic GSH concentrations were observed due to such chronic selenium treatment. Treatment with selenite (1 mg/kg) 24 hr prior to bromobenzene injection (2.5 mmol/kg) increased initially both o and p-bromophenols in the rat urine at 0-7.5 hr without affecting urinary thioethers. On the contrary, the ratio of thioethers to p-bromophenol was significantly higher in both 2.5 and 10 ppm selenite-pretreated (4 weeks) rats as well as a significant increase in the ratio of thioethers to total phenolic metabolites in 10 ppm and an increase close to significant in 2.5 ppm selenite-treated rats were observed initially at 0-7.5 hr urine samples. These results indicate that acute selenium pretreatment under certain conditions, favors increased hydroxylation of the intermediate bromobenzene epoxides, whereas higher detoxification of the epoxides involving hepatic glutathione (GSH)/GSH transferases pathway is more favored due to increased biosynthesis of GSH in certain chronic selenium treated rats.
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PMID:Influence of selenium on the metabolism of bromobenzene and a possible relationship to its hepatotoxicity. 401 88

Male Wistar rats were exposed (six hours/day, five days/week) to 0, 50, 300 or 600 p.p.m. of ethylbenzene vapour in the air, and killed after 2, 5, 9 or 16 weeks of exposure. After 600 p.p.m., liver-microsomal protein but not cytochrome P-450 concn. was slightly increased; NADPH-cytochrome c reductase was increased maximally by 30% (1.3-fold), 7-ethoxycoumarin O-deethylase (1.8-fold) and UDPG-transferase (2.3-fold). The increase in liver-cytosolic D-glucuronolactone dehydrogenase paralleled the glucuronidation activity (less than or equal to 2-fold). In the kidneys, only 7-ethoxycoumarin O-deethylase (less than or equal to 3.5-fold) and UDPG-transferase (less than or equal to 1.8-fold) showed dose-related increases. Ethylbenzene exposure did not deplete hepatic glutathione (GSH); kidney GSH was slightly increased (less than or equal to 1.3-fold) according to dose. Urine excretion of thioethers was increased with dose, and at 600 p.p.m. was eight times control levels. At 600 p.p.m. there was no increase in serum alanine aminotransferase activity, and liver cells showed slight proliferation of smooth endoplasmic reticulum, slight degranulation and splitting of rough endoplasmic reticulum and enlarged mitochondria, but no necrosis.
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PMID:Biochemical and morphological effects of long-term inhalation exposure of rats to ethylbenzene. 402 64

Carbon tetrachloride (CCl4)-induced hepatotoxicity was potentiated by pretreatment with beta-phenethyl alcohol, abundantly present in sake. The injury was determined by serum GPT levels and histological examination. Similar results were observed in ethanol- and phenobarbital-pretreated rats. Acetaminophen-induced hepatotoxicity was not accentuated by beta-phenethyl alcohol or ethanol pretreatment. The activities of liver microsomal enzymes, such as cytochrome P-450, cytochrome b5 reductase, aniline hydroxylase and aminopyrine demethylase, were not altered in beta-phenethyl alcohol-pretreated rats. Thus, CCl4-induced hepatotoxicity potentiation by beta-phenethyl alcohol administration is postulated to be due to a mechanism other than increased free radical generation.
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PMID:Potentiation of carbon tetrachloride hepatotoxicity by beta-phenethyl alcohol. 608 1

The effect of single, acute (7 pulses/sec., 0.75 volt) and chronic (4 pulses/sec., 0.75 volt) electroacupuncture (EA) treatment on alternate days for a period of 21 days on hepatic functions of rats were studied at cellular and subcellular levels. The points used for EA were Shenshu, Dachangshu and Zusanli. After chronic treatment, (a) protein, RNA, phospholipid, and cholesterol contents of whole liver and liver microsomal fraction increased significantly, (b) liver microsomal G-6-Pase activity increased significantly, (c) microsomal lipid peroxidation value decreased, (d) lipase activity increased. After acute treatment, (e) phospholipid, and cholesterol contents of the whole liver and liver microsomal fraction increased significantly, (f) liver microsomal G-6-Pase activity increased significantly, (g) liver microsomal lipid peroxidation value decreased, (h) GPT and lipase activity of liver increased. The parameters unchanged in acute treatment were as follows: (i) protein, RNA content, (j) GOT activity of the liver, (k) SGOT and SGPT activity, (1) hepatic triglyceride. The parameters unchanged in chronic treatment were as follows: (m) GOT and GPT activity of the liver, (n) SGOT and SGPT activity, (o) hepatic triglyceride. No apparent harmful effect of EA on rat hepatic functions is obvious from present study.
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PMID:Electroacupuncture and its effect on rat hepatic functions. 613 42


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