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)

Male Fischer 344 rats were used to investigate the hepatic effects of exposure to halothane under normoxic conditions (FIO2 = 0.21) in isoniazid-treated rats. Animals were treated with saline or isoniazid (50 mg/kg) for 7 days and then were exposed to either 1% halothane or air for 2 hr. One-half of the rats from each treatment and exposure group were killed 24 hr postexposure; the remaining were killed 4 days postexposure. Twenty-four hours following halothane exposure, serum transaminase levels were significantly elevated in isoniazid- compared with saline-treated rats (i.e., aspartate aminotransferase = twofold; alanine aminotransferase = seven-fold). Cholesterol levels were significantly depressed by halothane exposure in both saline- and isoniazid-treated rats. Other serum parameters indicative of hepatic and renal function were not different: alkaline phosphatase, total protein, total bilirubin, hematocrit, uric acid, creatinine, urea nitrogen, Na+, K+, Ca2+, and inorganic phosphate. Neither saline-treated nor isoniazid-treated rats exposed to air exhibited histologic evidence of hepatic damage. Halothane-exposed rats, however, showed a circumscribed disruption of cellular morphology. The most severe lesions were observed with isoniazid-treated animals with extensive pericentral hepatocellular necrosis and infiltration by leucocytes and Kupffer cells. Serum concentrations of two products of the oxidative metabolism of halothane, trifluoroacetic acid and bromide, were significantly elevated in isoniazid- compared with saline-treated rats. Serum levels of fluoride, a product of reductive metabolism, were not different. These results strongly suggest that hepatic injury following halothane administration can be produced by intermediates of oxidative metabolism.
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PMID:Halothane hepatotoxicity in Fischer 344 rats pretreated with isoniazid. 356 16

Aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) activity was measured in a group of 81 healthy subjects over 70 years of age and another of 180 younger persons, in order to investigate histograms and means of aminotransferase values in both groups and the variation in stimulation of these enzyme activities by pyridoxal 5'-phosphate (P5P) added in vitro. It was found that ASAT and ALAT mean values were significantly higher in both groups in the presence of P5P, than in the absence of P5P. ASAT and ALAT mean values obtained with and without P5P in old people were similar to those found in young subjects. In addition, mean stimulation percentages by P5P were identical in both groups.
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PMID:Aminotransferases in elderly people: influence of pyridoxal 5'-phosphate addition on the determination of serum aminotransferases in healthy elderly subjects. 357 54

A previously described digitonin-perfusion technique [Quistorff, Grunnet & Cornell (1985) Biochem. J. 226, 289-297], by which intracellular material of rat liver could be liberated, has been refined, now allowing release of cytosol of high purity from both periportal and perivenous parts of the same liver. The cytosolic fractions are obtained by perfusing the liver for short intervals (10-20 s) with digitonin (4-5 mg/ml), first in the normal perfusion direction and then, after an interval of 1-2 min, in the retrograde direction, the eluate being collected during and after both intervals. The technique is termed 'dual-digitonin-pulse perfusion'. The eluate fractions showed a peak specific activity of the cytosolic enzymes alanine aminotransferase (ALAT), lactate dehydrogenase (LDH) and pyruvate kinase (PK) of 3-5-fold higher than obtained in a biopsy from the same liver. For glutamine synthetase (GS) a 10-fold higher specific activity was obtained. Zonation, defined as the ratio of the specific activities in periportal and perivenous eluates, of ALAT, LDH and PK was 10, 1.7 and 0.70 respectively. Zonation of GS was less than 0.01. These factors may be modified by a slight zonation of cytosolic protein of 1.2-1.3. Peak concentrations in the eluate of ATP, ADP, Pi, NAD+ and glycerol 3-phosphate were 32.5 +/- 11.4, 19.9 +/- 4.3, 71.9 +/- 25.4, 2.41 +/- 0.83 and 6.84 +/- 2.74 nmol/mg of protein for periportal eluates. There was no difference between periportal and perivenous eluates except for glycerol 3-phosphate, which was significantly higher in perivenous eluates, 12.8 +/- 4.5 nmol/mg of protein.
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PMID:Dual-digitonin-pulse perfusion. Concurrent sampling of periportal and perivenous cytosol of rat liver for determination of metabolites and enzyme activities. 360 84

When aspartate- and alanine transaminase (AST and ALT, respectively) activities were studied in homogenates of rat cerebellum, brain cortex and brain stem (using a modified procedure by Raitman and Frenkel), addition of 50 microM pyridoxal-5-phosphate (PALP) increased 2-3-fold the activity studied. With an increase in PALP concentration from 6.25 microM up to 200 microM AST- and ALT-activities increased dose-dependently, while at 100-200 microM concentration of PALP saturation of the reaction occurred and 200 microM of PALP decreased the AST activity. 10 min preincubation of these homogenates without and in presence of 0.25 mM PALP led to a distinct increase in amount of ketoderivatives reacting positively with 2,4-dinitrophenyl hydrazine, most markedly elevated in the sample containing PALP. At the same time, prolongation of the preincubation period under standard conditions in presence of an excess of the substrates and 50 microM PALP did not cause any increase in AST- and ALT-activities. During studies of the transaminase activity in brain biopsy, in the material obtained after neurosurgical operations as well as in medico-biological experiments, the activity should be estimated using two sets of conditions: under standard conditions and in presence of 50-100 microM PALP but without preincubation with PALP.
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PMID:[The use of pyridoxal-5-phosphate in determining aminotransferase activity in brain tissue]. 363 9

Since ethanol consumption decreases hepatic aminotransferase activities in vivo, mechanisms of ethanol-mediated transaminase inhibition were explored in vitro using mitochondria-depleted rat liver homogenates. When homogenates were incubated at 37 degrees with 50 mM ethanol for 1 hr, alanine aminotransferase decreased by 20%, while aspartate aminotransferase was unchanged. After 2 hr, aspartate aminotransferase decreased by 20% and by 3 hr, alanine and aspartate aminotransferases were decreased by 31 and 23%, respectively. Levels of acetaldehyde generated during ethanol oxidation were 525 +/- 47 microM at 1 hr, 855 +/- 14 microM at 2 hr, and 1293 +/- 140 microM at 3 hr. Although inhibition of alcohol oxidation with methylpyrazole or cyanide markedly decreased ethanol-mediated transaminase inhibition, neither incubation with acetate nor generation of reducing equivalents by oxidation of lactate, malate, xylitol, or sorbitol altered the activity of either enzyme. However, semicarbazide, an aldehyde scavenger, prevented inhibition of both aminotransferases by ethanol. Moreover, incubation with 5 mM acetaldehyde for 1 hr inhibited alanine and aspartate aminotransferases by 36 and 26%, respectively. Cyanamide, an aldehyde dehydrogenase inhibitor, had little effect on ethanol-mediated transaminase inhibition. Thus, metabolism of ethanol by rat liver homogenates produces transaminase inhibition similar to that described in vivo and this effect requires acetaldehyde generation but not acetaldehyde oxidation. Since addition of pyridoxal 5'-phosphate to assay mixes did not reverse ethanol effects, aminotransferase inhibition does not result from displacement of vitamin B6 coenzymes.
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PMID:Evidence for the generation of transaminase inhibitor(s) during ethanol metabolism by rat liver homogenates: a potential mechanism for alcohol toxicity. 366 1

1. Glutamate dehydrogenase, aspartate transaminase and alanine transaminase were present in the gill, liver and muscle tissues of Periophthalmodon schlosseri and Boleophthalmus boddaerti. Both transaminases were found in the cytosol and mitochondria. 2. A complete purine nucleotide cycle was not present in the tissues studied. 3. Glutamine synthetase was not detected. Phosphate-dependent glutaminase was detected in both the cytosol and mitochondria. 4. Aspartate was the major substrate of ammoniagenesis in the mudskippers, though glutamate and glutamine were also oxidised. 5. Transdeamination was the major pathway for ammoniagenesis in the mudskippers studied.
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PMID:Ammoniagenesis in mudskippers Boleophthalmus boddaerti and Periophthalmodon schlosseri. 366 40

Using fully mechanized analytical equipment, interference by haemolysis in the determination of 26 clinical chemical parameters was determined quantitatively by adding haemolysate to serum. Haemoglobin concentrations up to 6.6 g/l caused essentially no interference in the following determinations: albumin (immuno-nephelometric), alpha-amylase, calcium, chloride, cholesterol, cholinesterase, creatinine, iron, glucose, glutamate dehydrogenase, uric acid, urea, sodium, inorganic phosphate, total protein, transferrin and triglycerides. In the presence of haemoglobin, erroneously high values were found for: lactate dehydrogenase (haemoglobin higher than 0.2 g/l), aspartate aminotransferase, potassium and acid phosphate (haemoglobin higher than 1.5 g/l), creatine kinase (haemoglobin higher than 2.5 g/l) and alanine aminotransferase (haemoglobin higher than 3.4 g/l). Erroneously low values were found for bilirubin (haemoglobin higher than 0.8 g/l), alkaline phosphatase and albumin (by electrophoresis) (haemoglobin higher than 1.5 g/l) and gamma-glutamyltransferase (haemoglobin higher than 3.0 g/l).
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PMID:Haemolysis as an interference factor in clinical chemistry. 371 97

To further evaluate the role of tryptophan and vitamin B6 in bladder carcinogenesis, male Fischer 344 rats were fed 0.2% N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) in semipurified diet or were given semipurified diet alone for 4 weeks. One week later, rats from each group were assigned for the remainder of the experiment to one of four experimental diets, labeled as follows: group 1, control semipurified; group 2, L-tryptophan excess (2%); group 3, vitamin B6-deficient (1.0 mg/kg diet); or group 4, L-tryptophan excess, plus vitamin B6-deficient diet. All surviving rats were killed at 80 weeks of the experiment. Throughout the study, body weights were reduced in the groups fed FANFT and, at 70 and 80 weeks, body weights were reduced in the groups given tryptophan excess. The incidence of urinary bladder carcinoma was highest in the group treated with FANFT, followed by diet with control tryptophan and vitamin B6 levels (40%). The disease incidence was reduced in the vitamin B6-deficient group (13%) and of an intermediate range in the groups fed a tryptophan excess with or without vitamin B6 deficiency (28-29%). Tumors at other sites were greatest in number in FANFT-treated rats fed vitamin B6-deficient diet with excess tryptophan and were significantly fewer in FANFT-treated rats fed vitamin B6-deficient diet alone. Animals given diet deficient in vitamin B6 consistently had depressed levels of alanine aminotransferase activity and plasma pyridoxyl phosphate. FANFT pretreatment decreased alanine aminotransferase activities in rats in some groups and the feeding of tryptophan had variable effects on alanine aminotransferase and plasma pyridoxyl phosphate levels. Urinary tryptophan metabolites were influenced by all treatments, but the results did not correlate with tumor yields. Urinary bladder ornithine decarboxylase activity was not altered in vitamin B6-deficient female rats. These results do not support the hypothesis that increased dietary L-tryptophan promotes bladder carcinogenesis in rats, but other dietary factors might modify the process following FANFT initiation.
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PMID:Effect of L-tryptophan excess and vitamin B6 deficiency on rat urinary bladder cancer promotion. 381 36

Screening by enzyme electrophoresis of isolates of New World Leishmania from different geographic areas revealed a number of stocks with enzyme profiles different from those produced by reference strains of described subspecies of L. mexicana, L. braziliensis, and L. donovani. Analysis by six enzymes (aspartate aminotransferase; alanine aminotransferase; malate dehydrogenase; glucose-6-phosphate dehydrogenase; phosphoglucomutase; and glucose-phosphate isomerase) showed that these stocks have identical enzyme profiles and form a distinct zymodeme grouping. These observations were confirmed using the technique of schizodeme analysis and by comparing the k-DNA fingerprints produced by the restriction enzymes MspI, BspRI and AluI. The stocks were further analyzed by monoclonal antibodies and did not react with any of a large panel of L. mexicana, L. braziliensis, and L. donovani species- and/or subspecies-specific monoclonal antibodies using either an indirect radioimmune binding assay or immunofluorescence. These stocks did, however, react with a panel of monoclonal antibodies specific for L. major (formerly L. tropica major). Furthermore, the stocks could not be differentiated from L. major reference strains by enzyme electrophoresis nor could they be distinguished qualitatively from L. major based on their reactivity patterns using 10 Old World cutaneous species- and subspecies-specific monoclonal antibodies. Kinetoplast DNA restriction enzyme profiles, however, were different between these stocks and L. major reference strains. The implications of these results are discussed including the existence of other L. major-like stocks currently misidentified or uncharacterized.
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PMID:Brazilian Leishmania stocks phenotypically similar to Leishmania major. 383 94

The interactions of nucleotides with phosphoenolpyruvate carboxykinase were studied by using the stereospecific thiophosphate analogues of GDP and GTP. The metal ion dependent stereoselectivity of these analogues was determined by using steady-state kinetics. The RP and SP isomers of guanosine 5'-O-(1-thiodiphosphate) (GDP alpha S) were substrates with low turnover, and a small preference for the RP isomer was observed. Neither the enzyme-metal nor the nucleotide-metal complex elicited any substantial change in the selectivity. Guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) exhibited no substrate activity for the enzyme, regardless of the cations. This nucleotide was a competitive inhibitor against GDP, however. Both RP and SP diastereomers of guanosine 5'-O-(1-thiotriphosphate) (GTP alpha S) were good substrates for phosphoenolpyruvate carboxykinase; in several cases, depending upon the cation, kcat and/or Vm/Km for the RP isomer is greater than for the substrate GTP. The enzyme-metal complex but not the nucleotide-metal complex affects the relative Km and the Vmax values. In contrast, guanosine 5'-O-(2-thiotriphosphate) (GTP beta S) (SP) is a much better substrate (greater than 50 times) than is GTP beta S (RP). The metal ions have little effect on the selectivity. These results suggest a specific interaction of the beta-phosphate of the nucleotide with the protein. The analogue guanosine 5'-O-(3-thiotriphosphate) (GPT gamma S) serves as a substrate to yield GDP and thiophosphoenolpyruvate. The latter was detected by 31P NMR and was shown to slowly hydrolyze to form phosphoenolpyruvate.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Guanosine thiophosphate derivatives as substrate analogues for phosphoenolpyruvate carboxykinase. 391 4


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