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)

The acute hepatotoxicity and response of hepatic cytochrome P450 to treatment with the three isomers of dichlorobenzene (DCB) have been investigated. The objectives were to estimate the onset of toxicity and to further elucidate the role of cytochrome P450 in the metabolism and toxicity of these compounds. In a study design employing one animal per dose level, Fischer-344 rats were gavaged with up to 25 different dosages, then evaluated 24 h later. Hepatic necrosis, serum alanine aminotransferase, and serum aspartate aminotransferase exhibited similar patterns demonstrating that ortho-DCB (o-DCB) was the most toxic in terms of both earliest onset and degree of response at higher dosages. For these three endpoints, meta-DCB (m-DCB) exhibited a lesser toxicity. Para-DCB (p-DCB) did not cause changes in these three endpoints, but hepatic degenerative changes were found. Total hepatic cytochrome P450 responses were also different after treatment with each isomer. The o-DCB produced a dose-dependent decrease in P450 beginning at dosages lower than the onset of necrosis and appeared to be a suicide substrate for P450. The m-DCB treatment increased P450 at dosages below the onset of necrosis and decreased P450 at higher dosages, with the decline preceding the onset of hepatocyte death. Treatment with p-DCB increased P450 beginning at 380 mg/kg. The combination of toxicity and P450 profiles has provided a framework for interpreting literature data on the metabolism and toxicity of the DCBs in rats. It is also noteworthy that o-DCB and p-DCB were administered at dosages several times the oral rat LD-50 (RTECS) without any lethality.
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PMID:The differential hepatotoxicity and cytochrome P450 responses of Fischer-344 rats to the three isomers of dichlorobenzene. 129 13

Liver necrosis was produced in rats by administering 3 doses of a mixture of carbon tetrachloride + olive oil, 2 ml/kg, ip. The liver damage was evidenced by the elevated levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma glutamyl transpeptidase (gamma-GT) and by histopathological observations of liver sections. Aspartate and glutamate administration (100 mg/kg, ip) significantly reduced these elevated levels of AST, ALT, and gamma-GT. Carbon tetrachloride induced liver necrosis was also found to be significantly reduced in aspartate and glutamate pretreated animals as observed macroscopically and histologically.
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PMID:Effect of aspartate and glutamate on carbon tetrachloride induced liver damage in rats. 209 35

The mechanisms of bromobenzene hepatotoxicity in vivo were studied in mice. The relationships among glutathione (GSH) depletion, lipid peroxidation, loss of protein thiols, disturbed calcium homeostasis and liver necrosis were investigated. Liver necrosis (as estimated by the serum glutamate-pyruvate transaminase (SGPT) level) appeared between 9 and 12 hr and increased at 18 hr. Lipid peroxidation which was already detectable at 6 hr in some animals, increased thereafter showing a good correlation with the severity of liver necrosis. Despite a quite fast depletion of hepatic GSH, a significant decrease in protein thiols could be observed at 12-18 hr only. Loss of protein thiols in both whole liver and subcellular fractions (microsomes and mitochondria) was correlated with lipid peroxidation. Also a good inverse correlation was seen between lipid peroxidation and the calcium sequestration activity of liver microsomes and mitochondria. The treatment of mice with desferrioxamine (DFO) after bromobenzene-intoxication completely prevented lipid peroxidation, loss of protein thiols and liver necrosis in the animals sacrificed 15 hr after poisoning. When, however, the animals were examined at 24 hr, although the general correlation between lipid peroxidation and liver necrosis was held, in some animals (about 30% of the survivors) elevation of SGPT was observed in the virtual absence of lipid peroxidation. It seems likely therefore that the liver damage seen during the first phase of bromobenzene-intoxication is strictly related to lipid peroxidation. It is, however, possible that in some animals in which for some reason lipid peroxidation does not develop, another mechanism of liver necrosis unrelated to lipid peroxidation occurs at later times.
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PMID:Lipid peroxidation, protein thiols and calcium homeostasis in bromobenzene-induced liver damage. 367 24

A clinicopathological study was undertaken in 15 cases of massive hepatic necrosis after shock. The GOT and GPT level exceeded 1000 units in 10 cases. The 15 cases consisted of 3 diagnosed as fulminant hepatitis clinically and 12 diagnosed as disseminated intravascular coagulation (DIC) or multiple systemic organ failure (MOF) from the unremarkableness of liver dysfunction. It was noteworthy that sepsis and surgery were closely associated with these lesions. The weight of the liver at autopsy ranged from 800 to 2,700 g. Liver necrosis was macroscopically characterized by clear demarcation of the necrotic areas sharply separated from the surrounding liver parenchyma, showing the appearance of so-called "map-like necrosis". Microscopically, the lesions in these subjects showed mainly the pattern of centrilobular necrosis. As observed in the burn shock case (case 12), the shock which provoked in different phases of time seemed to have repeated its attack. These liver necroses were considered to result from severe systemic circulatory disturbance or intrahepatic circulatory disturbance. The possibility is indicated that the generalized or univisceral Shwartzman reaction, and repeated and combined severe shock participated in the pathogenesis. Fibrin thrombi aggrevate tissue perfusion and accelerate anoxia. Heparin therapy seemed effective in these cases if administered at an appropriate time.
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PMID:Fatal hepatic necrosis after shock. 371 91

We studied portal hemodynamic changes by using duplex Doppler in 10 pigs with hepatic artery embolization (HAE) and hepatic artery ligation (HAL) and in 5 with HAL only. Serum concentration of alkaline phosphatase, ALT, direct and indirect bilirubin were determined simultaneously. Hepatic angiography and hepatic vascular cast were performed in the 5 pigs, and pathological examination in others. Portal venous velocity (PVV) and portal blood flow (PBF) increased after HAE, ALP, ALT, direct indirect bilirubin slightly elevated (P > 0.05) in the two groups after operation and most of them decreased subsequently within 7 days. Linear regression of PBF with ALP, ALT, direct and indirect bilirubin occurred in the experimental group. Liver necrosis was seen in all pigs of the experimental group and only one in the control group. Angiography and vascular cast showed that hepatic artery collaterals occurred at the portal hilus in the two groups and were more rich in the control group. Extrahepatic and intrahepatic arterial collaterals were seen from 1 to 3 weeks after HAE. The estimation of PVV and PBF by duplex Doppler may reflect the development of collaterals indirectly and is helpful in assessing the effect of HAE.
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PMID:[Experimental study of portal hemodynamic changes after hepatic artery embolization]. 825 4

Liver necrosis was produced in rats by administering 3 doses o a mixture o carbon tetrachloide+olive oil, 2 ml/kg, ip. The liver damage was evidenced by the elevated levels serun aspartate aminotrans ferase (AST), alanine aminotransferase (AIT) and gamma glutamyl transpeptidase (gamma-GT) and by histopathological observations of liver sections. Nitrendipine, nimodipine and nisoldipine (1 mg/100 g of rat, ip) significantly reduced these elevated levels of AST, AIT and gamma-GT. Carbon tetrachloride induced liver necrosis was also found to be significantly reduced in nitrendipine, nimodipine and nisoldipine pre-treated animals as observed macroscopically and histologically.
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PMID:Protection of CCL4-induced liver damage in rats by some calcium channel blockers. 855 Jan 25

Toxicity studies were performed by exposing F344/N rats and B6C3F1 mice to 2- and 4-chloronitrobenzene (CNB) by whole-body inhalation 6 hr/day, 5 days/week, for 13 weeks. Animals were evaluated for clinical chemistry (rats), hematology (rats), histopathology, and body/organ weights. Exposure concentrations were 0, 1.1, 2.3, 4.5, 9, and 18 ppm for 2-CNB and 0, 1.5, 3, 6, 12, and 24 ppm for 4-CNB. All rats in the 2-CNB study survived until the end of the study. Two male mice in the 18-ppm group in the 2-CNB study, however, died during Week 12; no deaths attributable to 4-CNB exposure occurred in rats or mice. In both studies, the mean body weight gains of exposed animals were similar to those of the respective controls. In rats, inhalation exposure to 2- or 4-CNB resulted in methemoglobinemia leading to a regenerative anemia and a variety of tissue changes secondary to the oxidative erythrocyte injury. In the 2-CNB study, methemoglobinemia resulted in a normocytic, normochromic, responsive anemia, whereas with 4-CNB, the methemoglobinemia was more severe and resulted in a macrocytic, hyperchromic, responsive anemia. Alterations of erythrocyte morphology were observed in both studies; changes included Heinz bodies, poikilocytes, and polychromasia. In rats, both isomers caused increases in serum activities of alanine aminotransferase and sorbitol dehydrogenase and increased bile acid concentrations. Microscopic liver changes included hemosiderin deposition in Kupffer cells (rats and mice exposed to 4-CNB), hepatocytomegaly (mice), and cytoplasmic basophilia (rats). Hepatocellular necrosis and chronic inflammation observed in mice were rather specific to the 2-CNB isomer, as only slight evidence of focal necrosis in the liver was observed in mice exposed to 4-CNB. Splenic lesions included hemosiderin accumulation capsular fibrosis, and increased hematopoietic cell proliferation. Increased bone marrow hemosiderin and hematopoietic cell proliferation and kidney tubule hemosiderin deposition were also observed. Other findings, attributed to chemical exposure but not to the hematotoxicity, were described. Lesions included hyaline droplet nephropathy and degeneration of the testis in male rats exposed to 4-CNB, inflammation of the harderian gland in rats exposed to 4-CNB, hyperplasia of the nasal cavity epithelium in rats exposed to 2-CNB, and hyperplasia of the forestomach epithelium in mice exposed to 4-CNB; these lesions have not been described previously in studies with these chemicals. Based on the exposure concentrations evaluated, A no-observed-adverse-effect level (NOAEL) for histopathological injury in mice was 4.5 ppm for 2-chloronitrobenzene and 6 ppm for 4-chloronitrobenzene; a NOAEL was not determined for rats.
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PMID:Thirteen-week inhalation toxicity of 2- and 4-chloronitrobenzene in F344/N rats and B6C3F1 mice. 881 32

Apoptosis is a process of active cell death, distinct from necrosis and characterized by specific morphological and biochemical features. Although the acute hepatotoxic effects of cadmium (Cd) are well described, little is known about the occurrence of apoptosis in Cd toxicity. Therefore, mice were injected with 5-60 mumol/kg i.p. of Cd and their livers were removed 1.5-48 h later and examined by light microscopy. Cd induced both a time- and dose-dependent increase in apoptotic index, severity of necrosis, and mitotic index. Apoptotic index peaked at 9-14 h after Cd administration and then decreased. The time course of apoptotic DNA fragmentation index, monitored by quantification of oligonucleosomal DNA fragments, correlated with the results obtained by histopathological analysis and a commercial in situ apoptotic DNA detection kit. Liver necrosis, as demonstrated by histology and serum alanine aminotransferase and sorbitol dehydrogenase assays, was most severe 14-48 h after Cd injection. Apoptosis was decreasing by 24 h while necrosis persisted. Replacement of liver tissue by blood lakes (peliosis hepatis) was observed after 14 h. The mitotic index increased gradually with time, indicating compensatory liver cell regeneration. There was a progressive increase in the severity of necrosis, apoptotic index, and mitotic index with increasing dose of Cd. These data demonstrate that apoptosis is a major mode of elimination of critically damaged cells in acute Cd hepatotoxicity in the mouse, and it precedes necrosis.
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PMID:Cadmium-induced apoptosis in mouse liver. 957 89

Although, diet restriction (DR) has been shown to substantially increase longevity while reducing or delaying the onset of age-related diseases, little is known about the mechanisms underlying the beneficial effects of DR on acute toxic outcomes. An earlier study (S. K. Ramaiah et al., 1998, Toxicol. Appl. Pharmacol. 150, 12-21) revealed that a 35% DR compared to ad libitum (AL) feeding leads to a substantial increase in liver injury of thioacetamide (TA) at a low dose (50 mg/kg, i.p.). Higher liver injury was accompanied by enhanced survival. A prompt and enhanced tissue repair response in DR rats at the low dose (sixfold higher liver injury) occurred, whereas at equitoxic doses (50 mg/kg in DR and 600 mg/kg in AL rats) tissue repair in AL rats was substantially diminished and delayed. The extent of liver injury did not appear to be closely related to the extent of stimulated tissue repair response. The purpose of the present study was to investigate the time course (0-120 h) of liver injury and liver tissue repair at the high dose (600 mg TA/kg, i.p., lethal in AL rats) in AL and DR rats. Male Sprague-Dawley rats (225-275 g) were 35% diet restricted compared to their AL cohorts for 21 days and on day 22 they received a single dose of TA (600 mg/kg, i.p.). Liver injury was assessed by plasma ALT and by histopathological examination of liver sections. Tissue repair was assessed by [3H]thymidine incorporation into hepatonuclear DNA and proliferating cell nuclear antigen (PCNA) immunohistochemistry during 0-120 h after TA injection. In AL-fed rats hepatic necrosis was evident at 12 h, peaked at 60 h, and persisted thereafter until mortality (3 to 6 days). Peak liver injury was approximately twofold higher in DR rats compared to that seen in AL rats. Hepatic necrosis was evident at 36 h, peaked at 48 h, persisted until 96 h, and returned to normal by 120 h. Light microscopy of liver sections revealed progression of hepatic injury in AL rats whereas injury regressed completely leading to recovery of DR rats by 120 h. Progression of injury led to 90% mortality in AL rats vs 30% mortality in DR group. In the surviving AL rats, S-phase DNA synthesis was evident at 60 h, peaked at 72 h, and declined to base level by 120 h, whereas in DR rats S-phase DNA synthesis was evident at 36 h and was consistently higher until 96 h reaching control levels by 120 h. PCNA studies showed a corresponding increase in cells in S and M phase in the AL and DR groups. DR resulted in abolition of the delay in tissue repair associated with the lethal dose of TA in ad libitum rats. Temporal changes and higher tissue repair response in DR rats (earlier and prolonged) are the conduits that allow a significant number of diet restricted rats to escape lethal consequence.
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PMID:Temporal changes in tissue repair permit survival of diet-restricted rats from an acute lethal dose of thioacetamide. 984 30

The effect of aqueous leaf extract of Azadirachta indica (A. indica) was evaluated in paracetamol induced hepatotoxicity in rats. Liver necrosis was produced by administering single dose of paracetamol (2 g/kg, p.o.). The liver damage was evidenced by elevated levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transpeptidase (gamma-GT) and by histopathological observations of liver sections. Aqueous A. indica leaf extract (500 mg/kg, p.o.) significantly (P < 0.01) reduced these elevated levels of AST, ALT and gamma-GT. Paracetamol induced liver necrosis was also found to be reduced as observed macroscopically and histologically.
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PMID:Effect of Azadirachta indica (Neem) leaf aqueous extract on paracetamol-induced liver damage in rats. 1091 97


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