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)

Diversion of portal blood in congenital portosystemic shunts (CPSS) results in liver atrophy and passage of toxins into the systemic circulation causing hepatic encephalopathy. In some dogs, there is indirect evidence for hepatic insufficiency, but histologic findings are equivocal. This study determined whether hepatocyte integrity in PSS is comprised at a subcellular level using analytical subcellular fractionation of liver biopsies. Six dogs with CPSS had hypoproteinemia (6/6), increased serum alkaline phosphatase (6/6) and alanine aminotransferase (4/6) activity, hypocholesterolemia (6/6), and decreased blood urea (2/6). Liver biopsy specimens had increased activities (mU/mg protein) of alkaline phosphatase (17.9 +/- 10.1; controls 5.1 +/- 5.3: P less than 0.01), but not of other plasma membrane enzymes. There were increased activities of endoplasmic reticular (neutral alpha-glucosidase: 1.67 +/- 0.7; controls 0.86 +/- 0.2: P less than 0.01) and lysosomal enzymes (N-acetyl-beta-glucosaminidase: 12.6 +/- 2.3; controls 6.24 +/- 2.7: P less than 0.01; alpha-mannosidase: 0.85 +/- 0.5; controls 0.39 +/- 0.3: P less than 0.05). Subcellular fractionation on reorientating sucrose density gradients showed a high-density peak of alkaline phosphatase suggestive of a specific increase in the biliary canalicular component of enzyme activity. Neutral alpha-glucosidase was shifted to denser fractions, indicative of an increase in the proportion of rough-to-smooth endoplasmic reticulum and consistent with enhanced synthesis of membranous enzymes. There was also evidence for increased fragility of intracellular organelles, particularly lysosomes. In contrast, histology showed either no abnormalities or minor degenerative changes compatible with hepatic underperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatic organelle pathology in dogs with congenital portosystemic shunts. 161 98

The antihepatotoxic properties of uridine-diphosphoglucose (UDPG, Toxepasi) have been evaluated in a well-established model of liver damage, the liver fluke infection (experimental fascioliasis in the rat), which causes a dramatic loss of the microsomal drug-metabolizing monooxygenase (MFO) and glucuronosyltransferase (GT) enzyme systems as a consequence of peroxidative damage to microsomal membrane lipids. Administration of 100 mg/kg UDPG i.p. to the infested rat for the entire course of the infection (40 days) positively affects the parameters reflecting the integrity of the liver cell (serum glutamate-pyruvate, GPT and glutamate-oxaloacetate, GOT, transaminases) and the detoxifying capacity of the liver (cytochrome P-450, cytochrome b5, cytochrome P-450-dependent p-nitroanisole O-demethylase and aniline hydroxylase activities, and the p-nitrophenol glucuronidation) and greatly reduces the lipid peroxidative phenomen in membranes from whole liver (tissue malonic dialdehyde content) and in membranes of the microsomal fraction (conjugated diene absorption). As a consequence of this, the total lipid and phospholipid contents of the liver are restored, there is minimal loss of latency of GT enzyme(s), cytochrome P-450 conversion to cytochrome P-420 is fairly negligible and total liver glutathione content is also restored. Therefore, UDPG restores liver function by protecting the endoplasmic reticulum membranes from the oxidative stress resulting from activation of the CN-insensitive respiratory burst of the phagocytic cells consequent to Fasciola hepatica invasion, migration and growth. It is very likely that UDPG acts as an effective antilipoperoxidative agent through both direct (as demonstrated by our in vitro experiments) and indirect mechanisms (stimulation of the glycolytic pathway, and hence of the reducing equivalents----glutathione----vitamin E supply).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Antihepatotoxic properties of uridine-diphosphoglucose in liver fluke infection. Experimental fascioliasis in the rat. 211 87

The present investigation examines the possibility that Cd and ethanol have a significant toxicological interaction. This examination was warranted as exposure to either chemical is known to compromise human health. Inasmuch as both chemicals affect the morphology, biochemistry, and physiology of liver, it seemed reasonable to consider liver as a possible site of interaction. Specifically, the hypothesis that ethanol alters the hepatotoxic action of Cd was evaluated. Accordingly, male rats were injected iv with hepatotoxic (3.0 mg/kg) or lethal (4.5 mg/kg) dosages of Cd, 24 hr after single-dose ethanol administration (7 g/kg, po). Cd-induced hepatotoxicity was assessed by measuring the activities of alanine aminotransferase, aspartate aminotransferase, and sorbitol dehydrogenase in serum collected 10 hr after Cd injection. Lethality was assessed by recording the number of survivors over a 7-day period. Prior exposure to ethanol substantially reduced the lethal and hepatotoxic properties of Cd. Two mechanisms were evaluated in an effort to explain ethanol-induced suppression of Cd hepatotoxicity. Ethanol pretreatment was postulated to: (1) enhance Cd excretion in bile thereby decreasing hepatic Cd content and/or (2) reduce the interaction between Cd and target sites in liver such as organelles and cytosolic high-molecular-weight (HMW) proteins. The first proposed mechanism was incorrect as the biliary excretion of Cd was nearly abolished and the concentration of Cd in whole liver increased (33%) as a result of ethanol exposure. The second proposed mechanism was a plausible explanation of ethanol-induced suppression of Cd hepatotoxicity because ethanol pretreatment decreased (approximately 60%) the content of Cd in nuclei, mitochondria, and endoplasmic reticulum, and nearly eliminated the association of Cd with cytosolic HMW proteins. Reduction in the concentration of Cd in potential target sites of intoxication was caused by a metallothionein-promoted sequestration of Cd in cytosol.
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PMID:Ethanol decreases cadmium hepatotoxicity in rats: possible role of hepatic metallothionein induction. 226 92

The clinical characteristics, laboratory results, and liver biopsy findings of seven workers with toxic liver injury associated with exposure to several solvents, including substantial levels of the widely used solvent dimethylformamide, are presented. Three patients had short exposure (less than 3 months), four long exposure (greater than 1 year). Among those with brief exposure, symptoms included anorexia, abdominal pain, and disulfiram-type reaction. Aminotransferases were markedly elevated with the ratio of alanine aminotransferase to aspartate aminotransferase always greater than 1. Liver biopsy showed focal hepatocellular necrosis and microvesicular steatosis with prominence of smooth endoplasmic reticulum, complex lysosomes, and pleomorphic mitochondria with crystalline inclusions. Among workers with long exposure, symptoms were minimal and enzyme elevations modest. Biopsies showed macrovesicular steatosis, pleomorphic mitochondria without crystalloids, and prominent smooth endoplasmic reticulum, but no evidence of persisting acute injury or fibrosis. Abnormal aminotransferases in both groups may persist for months after removal from exposure, but progression to cirrhosis in continually exposed workers was not observed. We conclude that exposure of these workers to solvents, chiefly dimethylformamide, may result in two variants of toxic liver injury with subtle clinical, laboratory, and morphological features. This may be readily overlooked if occupational history and biopsy histology are not carefully evaluated.
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PMID:Clinical and pathological characteristics of hepatotoxicity associated with occupational exposure to dimethylformamide. 237 79

The chronic oral toxicity of propiverine hydrochloride (P-4), a new anti-pollakiuria agent, was studied in beagle dogs. Groups of 6 males and 6 females were treated with P-4 at doses of 0, 0.3, 1, 3, 9 mg/kg/day for one year and thereafter 2 animals of both sexes in each group were placed on withdrawal for one month. During administration and recovery period, no death occurred in any dosed animals. As a toxic sign, only the frequency of vomiting was increased in animals of 1, 3 and 9 mg/kg/day groups. Body weight, food and water consumption were not affected by the P-4 administration. In serum chemical examinations, gamma-GTP activity was increased in both sexes of 9 mg/kg/day group at 6 month of administration. Further decrease in total and free cholesterol, triglyceride and phospholipid, increase in GPT activity were detected in some animals of 9 mg/kg/day group at 12 month of administration. In addition decreasing tendency in levels of albumin was noted in males of 9 mg/kg/day group at 9 and 12 month of administration. And also, a gradual increase in total protein level and a gradual decrease in alkaline phosphatase activity were seen in control group, but in females or males of 9 mg/kg/day group, those changes were mild. Urine pH rised slightly in females of 3 mg/kg/day group and in both sexes of 9 mg/kg/day group. No specific findings attributable to P-4 treatment were detected in ECG, heart rate, funduscopy, hematology, fecal occult blood test and necropsy. The absolute and/or relative liver weight in males of 3 and 9 mg/kg/day groups were significantly increased. Light-microscopically, the hypertrophy of hepatocytes characterized by homogenization and enlargement of cytoplasmic space, and concentric inclusions in hepatocytic cytoplasm were detected in both sexes of 3 and 9 mg/kg/day groups. Corresponding to these microscopical findings, the following changes were observed electron-microscopically, the proliferation of smooth surfaced endoplasmic reticulum in hepatocytes in both sexes of 1, 3 and 9 mg/kg/day groups, lamellar bodies in hepatocytes in females of 3 mg/kg/day group, and in both sexes of 9 mg/kg/day group, and annulate lamellae in hepatocytes were detected in one female of 9 mg/kg/day group. After the recovery period, the above mentioned abnormalities were markedly attenuated or disappeared except the changes in hepatocytes. From these results, it seemed that 9 mg/kg/day of P-4 might be safety dose.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[One-year chronic oral toxicity study of propiverine hydrochloride in dogs followed by one-month recovery]. 260 51

In isolated, hemoglobin-free perfused livers of fasted rats, formaldehyde at an initial concentration of 10 mmol/l produced toxicity as evidenced by a release of enzymes (GPT, SDH) and of glutathione (mainly GSSG) into the perfusate, an accumulation of calcium in the liver, and a depletion of hepatic glutathione. Formaldehyde also led to an enhanced release of malondialdehyde into the perfusate, indicating peroxidative processes and decreased hepatic oxygen consumption by about 50-70%. The electron microscopic investigation of formaldehyde-exposed livers showed a destruction of the mitochondria (ruptured membranes, loss of the cristae) and some damage of the rough endoplasmic reticulum. Feeding the rats prior to surgery attenuated the hepatotoxic effects of 10 mmol/l formaldehyde. At an initial concentration of 3 mmol/l, formaldehyde did not release enzymes from livers of fed or fasted rats but only from those whose glutathione content had been depleted by treatment with phorone (250 mg/kg ip 2 h earlier). Formaldehyde liberated glucose and lactate from the livers of fed but not from those of fasted rats, indicating anaerobic energy supply in the fed state. The hepatotoxic action of formaldehyde is not due to its metabolism to formate or to the 10% methanol added as a stabilizing agent to the commercially available 37% solution named formalin. In conclusion, by destruction of mitochondria, formaldehyde inhibits aerobic energy supply and thereby presumably produces hepatocellular damage.
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PMID:Mechanistic study on formaldehyde-induced hepatotoxicity. 275 59

The concentration of serum immunoreactive prolyl 4-hydroxylase (S-IRPH) was determined in patients with various liver diseases by the radioimmunoassay developed previously. S-IRPH values were elevated in acute hepatitis (p less than 0.01), hepatocellular carcinoma (p less than 0.05), metastatic liver neoplasm (p less than 0.01) and cholestatic diseases (p less than 0.001), but no significant elevation was seen in chronic hepatitis or liver cirrhosis. The mean value of S-IRPH was highest in cholestatic diseases, and next highest in acute hepatitis. In addition to acute hepatitis, S-IRPH was increased in other conditions of hepatocellular damage such as exacerbation of chronic hepatitis or immediately after transcatheter arterial embolization of hepatocellular carcinoma. In cases of hepatocellular damage S-IRPH varied concurrent with cytoplasmic enzyme (AST, ALT and LDH) levels and in cases of cholestatic diseases with biliary enzyme (Al-P and gamma GTP) levels. These properties appear to be unique among serum enzymes. The characteristics of S-IRPH were considered to be related to its unique subcellular localization within the cell, ie the membrane of rough endoplasmic reticulum.
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PMID:Studies on serum immunoreactive prolyl 4-hydroxylase in liver diseases--its elevation both in hepatocellular damage and cholestatic diseases. 284 41

Primidone, phenytoin, or phenytoin and primidone in combination were given to healthy Beagle dogs for 6 months. Serum biochemical changes in dogs given primidone alone or phenytoin and primidone in combination for the entire 6-month test period included increased activities of alanine aminotransferase, alkaline phosphatase (AP), and gamma-glutamyltransferase, and decreased concentrations of albumin and cholesterol. Changes in dogs given phenytoin alone were limited to increased AP activity and decreased albumin concentration. Sulfobromophthalein excretion and conjugated bile acid concentration were within normal limits. All dogs given primidone alone or phenytoin alone remained clinically healthy throughout the treatment period. Three of 8 dogs given both drugs in combination became clinically ill after 9, 14, and 15 weeks of treatment, and were euthanatized. Two of the dogs developed clinical jaundice. In addition to the serum biochemical abnormalities observed in clinically healthy dogs, these dogs developed hyperbilirubinemia, delayed sulfobromophthalein excretion, and increased conjugated bile acid concentrations. Histologic examination of the liver showed intracanalicular casts of bile pigment typical of intrahepatic cholestasis in all 3 dogs. Histologic findings characteristic of treated dogs included hepatocellular hypertrophy attributable to hyperplasia of the smooth endoplasmic reticulum. Single-cell necrosis and multifocal lipidosis were observed in individuals of all treatment groups. Electron microscopy of the liver showed dilated bile canaliculi and damaged sinusoidal epithelium in dogs given both drugs. The elevated serum AP activity, associated with anticonvulsant drug therapy, was found to be exclusively the liver isoenzyme by cellulose acetate electrophoresis. The hepatic AP was localized to primarily the canalicular membranes by enzyme histochemistry. There was a statistically significant positive correlation between the AP activities of liver and serum. The results of this study indicate that long-term administration of anticonvulsant drugs to dogs is associated with clinical, serum biochemical, and histologic evidence of hepatic dysfunction. High drug dosage contributed most to abnormal serum biochemical test results, and combining phenytoin with primidone was responsible for more severe electron microscopic lesions of the liver of surviving dogs and for the death of 3 dogs.
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PMID:Effects of long-term primidone and phenytoin administration on canine hepatic function and morphology. 285 43

Hepatocytes from 12-day-old rats, pre- and post-natally exposed to alcohol, together with those from pair-fed controls, were isolated and subfractionated in six cell subpopulations on Percoll density gradients. These cells were characterized using a combination of biochemical and stereological methods. The low density cells (F2) mainly showed biochemical and stereological features of perivenous hepatocytes, whereas the heavier cells (F6) were primarily periportal hepatocytes. The alcohol-metabolizing enzymes, alcohol dehydrogenase and aldehyde dehydrogenase (high and low Km) showed more activity in the F2 fraction. Alcohol-altered mitochondria and Golgi apparatus occurred mainly in F2 cells, whereas the endoplasmic reticulum and lysosomes appeared to be more altered in the F6 hepatocytes. Alcohol also induced the appearance of some small hepatocytes, with a well-developed rough endoplasmic reticulum and an increased number of mitochondria. Biochemical data indicated that glutamate dehydrogenase and alanine aminotransferase were more affected in F2 cells from alcohol-treated rats, and that the activity of the ethanol-metabolizing enzymes was alos reduced in these hepatocytes. Our results indicate that alcohol exposure during zonal development in the liver could have a selective effect on specific cell components depending on the acinar zone, and that the perivenous hepatocytes appear to be more damaged under these conditions.
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PMID:A biochemical and stereological study of neonatal rat hepatocyte subpopulations. Effect of pre- and postnatal exposure to ethanol. 289 91

An increase in relative liver weight, the total liver DNA content, hepatocyte volume and the total surface area of the membranes of mitochondria and the granular and smooth endoplasmic reticulum of hepatocytes, but a decrease in the size of the nuclei, were found in adult male rats fed three weeks on a high protein diet compared with animals given a standard laboratory diet. Serum transaminase (ALT, AST) and alkaline phosphatase activity was practically the same as the control values. Rats fed three weeks on a low protein diet showed a decrease in relative liver weight, in the total liver DNA content, in hepatocyte and nuclear volume and in ploidy, and also in the surface area of the membranes of the mitochondria and the smooth and granular endoplasmic reticulum; conversely, the number of binucleate hepatocytes rose. Serum ALT, AST and alkaline phosphatase activity was mildly, but statistically significantly elevated.
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PMID:Effect of long-term administration of a high protein or low protein diet on rat liver. Morphological and biochemical findings. 294 5


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