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 guinea-pigs protractedly exposed per os to sulphur in a daily dose of 200 mg/kg body weight show, depending on the exposure period, in their livers, varied intensity of histochemical enzymatic reactions and different ALAT activity in blood serum. After 30 days' exposure to sulphur the intensity of enzymatic reactions is almost similar to that in controls or somewhat lower, whereas in the blood serum there is an increase in the activity of alanine aminotransferase. After the lapse of 90, 180 and 270 days of exposure, the animals' livers are observed to disclose a rise in reactions to the activity of mitochondrial, lysosomal enzymes as well as G-6-P-ase, esterase AS and ATP-ase, whereas in blood serum AspAT and ALAT reveal no difference in the activity level with regard to the control value.
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PMID:[Liver enzymes in the guinea pig after chronic oral administration of elemental sulfur]. 629 64

To study the relationship between lipid peroxidation and cellular damage we studied three compounds known to evoke lipid peroxidation (cumene hydroperoxide, CHP), hepatocellular injury (thioacetamide, TAA) or both (carbon tetrachloride, CCl4). Phenobarbital-induced male rats were treated with one of the three agents and lipid peroxidation was monitored via the measurement of exhaled ethane. Treatment with both, CCl4 and CHP resulted in an increased ethane expiration, whereas TAA did not. When liver-specific serum enzyme activities (GPT, SDH) were investigated 24 h later, however, hepatotoxicity was evident only in rats treated with either CCl4 or TAA. The ATP-dependent Ca2+-sequestration activity of microsomal membranes, suggested to be a final common pathway leading to cellular death, was studied in microsomes isolated from rats treated with either agent. 2 h after treatment with CCl4 or TAA a clear inhibition was seen which persisted after 24 h in the case of CCl4 only. CHP did not affect the Ca2- -pump activity. Thus, a clear correlation between cellular damage and lipid peroxidation cannot be expected in every case. An impairment of the microsomal calcium-pump, however, seems to be a crucial event which leads to hepatocellular injury.
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PMID:Interrelationship between in vivo lipid peroxidation, microsomal Ca2+-sequestration activity and hepatotoxicity in rats treated with carbon tetrachloride, cumene hydroperoxide or thioacetamide. 662 17

The biochemical and morphological effects of 2, 10 and 100 mM of D-galactosamine (GalN) were studied in isolated rat hepatocytes during 2 h of incubation. Lactate dehydrogenase (LDH), alanine aminotransferase (ALAT) and cell viability did not change, whatever the concentration used. The variations observed, which were dose dependent, included a large drop in ATP levels and inhibition of RNA and protein synthesis. A very high concentration of GalN was necessary, however, to induce a significant decline in methionine adenosyltransferase activity compared to control cells. The use of L-[methyl-14C]methionine during cell incubation with GalN demonstrated a decrease of S-adenosyl-L-methionine (SAMe) and an accumulation of L-methionine content related to the GalN concentration. These results suggested that an hepatotoxic agent such as GalN was able to induce disturbances of methionine metabolism. Some of the ultrastructural changes observed were different from those previously found in vivo, in rats given GalN intraperitoneally, underlining the marked difference between in vivo and in vitro intoxication.
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PMID:Methionine metabolism and ultrastructural changes with D-galactosamine in isolated rat hepatocytes. 674 76

The author carried out a dynamic study on the metabolic changes in liver under the influence of nicotinic acid, administered singly by intramuscular injection in a dose of 2mM/kg of body weight. She examined at the 1th, 3th, 6th and 24th hour the changes in the levels of nicotine-amide coenzymes (NAD, NAD-H and NADP), adenine nucleotides (ATP, ADP and AMP), the metabolic lactate and pyruvate and the enzymes LDH, MDH, GOT and GPT. The obtained data were compared with those of the control groups, treated with saline and killed at the same intervals as the experimental animals. Furthermore she made also a comparison with an intact group, presented as O group, whose values served as basal. The obtained data showed that after application of the nicotinic acid (NA) complex metabolic changes occurred in liver, due to its basic effects-stimulation of biosynthesis of nicotinamide coenzymes and inhibition of lipolysis in the fatty tissue. Most probably the effect on the biosynthesis of NAD was primary, which showed later substantial regulatory influence both on lipolysis in the fatty acid and on the metabolization of mobilizing lipids on behalf of the liver. Parallel occurring metabolic processes in the aorta and in the vascular wall in general, stimulation of the biological oxidation and bioenergetics formed the whole antilipolytic and antiarteriogenic action of nicotinic acid.
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PMID:[Metabolic changes in the liver as affected by nicotinic acid]. 730 22

Possible liver damage induced by chemicals or drugs must be detected early during drug development or industrial exposure, although damage is still difficult to predict, especially when immunotoxicity is involved. Liver toxicity may result from cytolysis, steatosis, cholestasis, phospholipidosis, or vascular lesions, most the outcome of a disadvantageous balance between chemicals or metabolites vs protective mechanisms, resulting from chemical dosage, genetic factors, or the immunoallergic status of the patient. Drug metabolism, lipid peroxidation, and thiol oxidation are frequently involved in liver toxicities. Classical guidelines in toxicology propose many methods for liver toxicity assessment: histology; chemical changes in hepatic tissue (lipids, glutathione, enzymes); physiological changes in biosynthesis (proteins, glycoproteins); excretion function (fructose); drug metabolism; and concentrations of related enzymes (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and gamma-glutamyltransferase) in blood. In vitro studies in human or animal hepatocytes or tumor-derived cell lines are useful in detecting hepatocellular lesions by cell viability, glutathione concentration, amount of lactate dehydrogenase released, cellular ATP, morphology (blebs), and drug metabolism.
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PMID:Manifestations of chemically induced liver damage. 749 49

Chlordecone (Kepone) amplification of CCl4 toxicity occurs at small, nontoxic levels of chlordecone and CCl4 and results in highly increased irreversible hepatotoxicity culminating in lethality. Although it is generally assumed that CCl4 lethality is due to hepatic failure, no definitive studies are available in the literature bridging massive liver failure and death. The present studies were designed to evaluate whether hepatic failure is the cause of the lethality during chlordecone-amplified CCl4 toxicity. Male Sprague-Dawley rats were maintained on control or a chlordecone (10 ppm) diet for 15 days and injected with CCl4 (100 microliters/kg, ip) on Day 16. Rats were killed at 0, 6, 12, 24, 36, and 48 hr after CCl4 challenge. Hepatic failure was evaluated by measuring plasma glucose, ammonia, bilirubin, aspartate transaminase (AST), alanine transaminase (ALT), sorbitol dehydrogenase (SDH), hepatic ATP, glycogen, and by histological and histomorphometric analyses. Plasma creatinine, urea, and kidney histopathology were also assessed for possible renal injury. As expected CCl4 administration to chlordecone-pretreated rats resulted in 20% lethality by 36 hr, which progressed with time, and all rats died within 72 hr. A significant and progressive hypoglycemia was observed with a 60% reduction in plasma glucose at 48 hr. Hepatic glycogen content dropped precipitously. Similarly, hepatic ATP levels remained suppressed (80% of control) at all the time points studied. Plasma ammonia levels were significantly elevated, and by 48 hr, a threefold increase was observed. Plasma ALT, AST, SDH, and bilirubin increased progressively until the death of rats receiving the chlordecone + CCl4 combination.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatic failure leads to lethality of chlordecone-amplified hepatotoxicity of carbon tetrachloride. 750 40

In the adipose tissue, besides fatty acid synthesis (FA-S) from glucose, which includes several mitochondrial steps, FA-S from glutamate has been demonstrated. FA-S from glutamate takes place in the cytosol through the backward pathway of Krebs cycle (BPKC) and is due to the sequential action of (1) alanine aminotransferase (ALT, EC 2.6.1.2), which is presence of pyruvate converts glutamate to oxoglutarate; (2) isocitrate dehydrogenase (NADP) (ICDH, EC 1.1.1.42), which converts oxoglutarate to isocitrate; (3) aconitate hydratase (ACO, EC 4.2.1.3), which transforms isocitrate to citrate: and (4) ATP citrate-lyase (ATP-CL, EC 4.1.3.8), which splits citrate to yield the acetyl-CoA needed for FA-S. We studied the enzymes involved in BPKC in homogenates of human adipose tissue. In normal subjects, the cytosolic activity (mumol/min/g protein) was: ALT = 10.3 +/- 1.1, ICDH = 29.5 +/- 2.8, ACO = 2.05 +/- 0.23, and ATP-CL = 1.2 +/- 0.2. Mitochondria contained less or no activity, values being 20, 9, 11, and 0% of total for ATL, ICDH, ACO, and ATP-CL, respectively. BPKC enzymes are more active than the enzymes limiting FA-S from glucose, i.e., phosphofructokinase (EC 2.7.1.11), pyruvate carboxylase (EC 6.4.1.1), and pyruvate dehydrogenase (EC 1.2.4.1). In the obese patients, cytosolic ALT and ATP-CL were increased (12.9 +/- 0.7, P < 0.05, and 2.28 +/- 0.27, P < 0.01, respectively) compared to normal, while ICDH was not changed (ACO could not be studied). Similar changes were obtained by expressing enzyme activity per fat cell number.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Fatty acid synthesis from glutamate in the adipose tissue of normal subjects and obese patients: an enzyme study. 755 12

The liver has been judged relatively resistant to ischemia, but prolonged inflow occlusion at normothermic conditions can produce evidence of reversible or irreversible hepatocellular damage. Cytoprotective agents have been used both experimentally and clinically to afford extended viability of hepatocytes under reduced perfusion. One agent, prostaglandin E1, has been described clinically as effective in sustaining liver function under ischemic conditions. We have sought to verify this observation in an experimental model using prolonged normothermic inflow occlusion. Twenty miniature pigs were anesthetized and subjected to subtotal normothermic hepatic inflow occlusion (portal vein, hepatic artery, choledochal vessels) to allow for sufficient splanchnic decompression. Half of the animals received pretreatment with prostaglandin E1 (alprostadil) 500 micrograms intravenously. Inflow occlusion was maintained for 2 hours followed by reperfusion and killing 24 hours later. As a measure of functional preservation, the tissue adenine nucleotides adenosine monophosphate, diphosphate, and triphosphate (AMP, ADP, ATP) were measured in ischemic liver by freeze-clamping and high-performance liquid chromatography during occlusion and after reperfusion. Cytosolic enzyme determinations (aspartate transaminase, alanine transaminase, lactate dehydrogenase) were also made before occlusion and after reperfusion. As a possible indicator of cellular injury, blood ionized Ca++ was measured before inflow occlusion and after reperfusion. Although no difference was found in levels of AMP and ADP between prostaglandin E1 and control animals, ATP levels rose significantly higher during recovery in prostaglandin E1 animals at 60 minutes and 24 hours after reperfusion (13.97 +/- 1.29 and 13.60 +/- 0.91 mumoles/gm dry weight prostaglandin E1 vs. 9.25 +/- 0.97 and 9.80 +/- 0.85 mumoles/gm dry weight co control, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effect of prostaglandin E1 on liver adenine nucleotides and cytoplasmic enzymes in a porcine model of normothermic hepatic ischemia. 759 Jun 75

The in vivo effects of ascorbic acid on the reoxygenated liver tissue were examined, with regard to the following effects: (i) the effects of scavenging radicals and/or reducing peroxidative reactions, and (ii) the effects of the chelation with low-molecular-weight iron and increasing its reactivity (radical production). Ascorbic acid is one of the water-soluble vitamins known to have various physiological effects involving both chelating and reducing properties at once. Lipid peroxidation of the reoxygenated liver tissue estimated by the production of TBARS (thiobarbituric acid-reactive substance) and LPO (lipid hydroperoxides) was suppressed effectively by the preischemic intraperitoneal administration of ascorbic acid. Ascorbic acid also showed this anti-oxidant effect in a dose-dependent manner. The analysis of the levels of ascorbic acid and glutathione of the liver tissue revealed that ascorbic acid works as an anti-oxidant probably by being oxydized finally to dehydroascorbic acid just after the reoxygenation. The latter was reduced to ascorbic acid again, coupled with the conversion of GSH to GSSG in the postischemic time course. The predominant effect of ascorbic acid on the reoxygenated liver tissue seems to be caused by the scavenging radicals and/or reducing peroxidative reactions, rather than by chelating iron and increasing its reactivity (radical production). Cellular integrity (estimated by the release of GOT, GPT, and LDH) and the energy state of the postischemic liver tissue (estimated by the tissue ATP level) were also well preserved by the administration of ascorbic acid.
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PMID:The in vivo cytoprotection of ascorbic acid against ischemia/reoxygenation injury of rat liver. 773 75

This study aimed at analyzing the involvement of platelet activating factor (PAF) in ischemia/reperfusion injury (I/R) of the liver. Male Wistar rats under pentobarbital anesthesia were subjected to 60 min of normothermic ischemia of the left and median liver lobes, followed by 30 min of reperfusion in vivo. Blood pressure and body temperature were controlled throughout the experiment. Preischemic injection of a specific PAF antagonist (BN52021, 5 mg/kg body mass) resulted in significant reduction of postischemic enzyme loss into the serum from the vascular endothelium (purine nucleoside phosphorylase: 56.9 +/- 11.4 vs 86.6 +/- 20.4 U/l**) and the hepatic parenchyme (alanine aminotransferase: 176 +/- 60 vs 519 +/- 180 U/l***), accompanied by a significant increase of hepatic bile production (1.28 +/- .32 vs 0.80 +/- 0.16 microliter/g/min*) and tissue levels of ATP (6.12 +/- 1.73 vs 4.21 +/- 1.30 mumol/g*). Laser Doppler flowmetry revealed a significant improvement by BN52021 of left lobular erythrocyte flux recovery from 27 +/- 25 to 78 +/- 19% of respective preischemic control values. The data give evidence for an implication of PAF in I/R damage to the vascular endothelium and in impaired parenchymal function of the liver, probably due to altered microvascular reperfusion. Treatment with PAF antagonists should improve results after liver surgery under ischemic conditions. (*;**;***: P < 0.05; 0.01; 0.001).
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PMID:Involvement of platelet activating factor in microcirculatory disturbances after global hepatic ischemia. 774 67


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