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At least 361 records · Page 20Linked to original sources
PubMed1995

The temporal profile of increased transaminase levels in patients with acetaminophen-induced liver dysfunction.

STUDY OBJECTIVE: It is often taught that acetaminophen-induced liver dysfunction occurs only after a latent period of 24 to 48 hours. This study was designed to evaluate the temporal profile of transaminase levels in patients with acetaminophen-induced hepatotoxicity. DESIGN: Prospective data collection using standard poison control center data sheets. PARTICIPANTS: Hospitalized patients with acetaminophen exposure who were reported to the Long Island Poison Control Center between January 1993 and June 1994. Patients who presented within 24 hours of ingestion and in whom increased aspartate aminotransferase (AST) levels developed during hospitalization were included in the data analysis. Patients who presented more than 24 hours after ingestion, who had ingested another potentially hepatotoxic agent, or who had ingested acetaminophen over a period of more than 2 hours were excluded. RESULTS: Of 1,825 patients with reported acetaminophen exposure, 779 had potentially toxic ingestions and were examined in an emergency department. Of 291 patients with toxic acetaminophen levels who were admitted, 36 (12%) had increased levels of AST at some point during hospitalization. All received oral N-acetylcysteine within 2.5 hours of presentation. In 11 of 19 patients who met all inclusion criteria (58%), AST levels were noted to be increased in the 24 hours after ingestion. The median peak AST level was 422 IU/L (range, 74 to 8,538 IU/L). AST levels peaked within 48 hours in 4 patients (21%) and within 72 hours in 18 patients (95%). Six of eight patients with peak AST levels greater than 1,000 IU/L had increased transaminase levels during the 24 hours after acetaminophen ingestion. CONCLUSION: Acetaminophen poisoning may cause the serum transaminase level to increase during the 24 hours after ingestion.

Acetaminophen↗
PubMed2001

Analysis of arylsulfatases A and B, acid phosphatase, lactate dehydrogenase, and aspartate transaminase in chronic periapical lesions of endodontic origin.

Attempts were made to detect and measure the activities of arylsulfatases. A&B acid phosphatase, lactate dehydrogenase, and glutamate oxaloacetate transaminase (aspartate transaminase) enzymes in human chronic lesions of endodontic origin. Thirteen periapical lesions of endodontic origin and 11 noninflamed control periapical tissues were obtained. The specimens were carried to the laboratory on liquid nitrogen and kept at -70 degrees C. Samples were thawed, homogenized, and then assayed for enzyme activities. The specific activities of arylsulfatase A (nmol/hr/mg protein) were 55.0+/-10.7 (chronic lesions) vs. 3.4+/-2.2 (controls) (p < 0.01). Arylsulfatase B specific activities (nmol/hr/mg protein) were 50.3+/-6.4 (chronic lesions) vs 91.8+/-18.4 (controls). Total acid phosphatase activities (mU/mg protein) were 45.8+/-6.6 (chronic lesions) vs. 26.8+/-3.1 (controls). Lactate dehydrogenase activities (Berger-Broida units/mg protein) of the chronic periapical lesions were significantly higher than the control group (362+/-63.2) vs. (140+/-46.0) (p < 0.05). There was no significant difference between the specific activities of aspartate transaminase in chronic lesions and the control group (68.0+/-14.5) vs. (53.0+/-10.4) mU/mg protein).

Acid Phosphatase↗
PubMed1977

Subcellular Localization and Developmental Changes of Aspartate-alpha-Ketoglutarate Transaminase Isozymes in the Cotyledons of Cucumber Seedlings.

The total activity of aspartate-alpha-ketoglutarate transaminase in the cotyledons of cucumber (Cucumis sativus L.) seeds increased 17-fold during the first 2 days of germination in darkness and then declined gradually to 20% of the peak activity after 10 days. Exposure of the seedlings to light at day 3 accelerated the decline. The enzyme in the cotyledon extracts from seedlings at various ages was resolved into six distinct isozymes by starch gel electrophoresis. Isozymes 1 and 2 were glyoxysomal isozymes with different developmental patterns. Isozyme 1 followed the developmental pattern of the total enzyme activity in darkness, and was rapidly eliminated upon illumination. Isozyme 2 increased in activity to a peak at day 2 and declined rapidly thereafter, and disappeared completely at day 6; this developmental pattern was independent of light. No major difference in the optimal pH for activity, substrate specificity, and reversibility was observed between isozymes 1 and 2. The combined developmental pattern of isozymes 1 and 2 during germination correlated with that of the glyoxysomes. Isozyme 3 was located in the cytosol and its developmental pattern followed that of the total activity. Isozymes 4,5, and 6 were plastid isozymes and appeared only after 2 days of germination. Unlike many other chloroplast enzymes, the appearance of the chloroplast transaminase isozymes was under temporal control and was independent of illumination. No enzyme activity was detected in isolated mitochondria. The findings illustrate a complicated cellular control system for the appearance of various organelle-specific transaminase isozymes and thus the amino acid metabolism during germination.

Journal Article↗
PubMed2006

D-dopa is unidirectionally converted to L-dopa by D-amino acid oxidase, followed by dopa transaminase.

1. Many studies have shown that administration of d-3, 4-dihydroxyphenylalanine (D-dopa) produces contralateral rotation in hemi-parkinsonian animals comparable to L-dopa, with less potency and slower onset. It was postulated that D-dopa was converted to L-dopa to produce these effects. 2. To investigate the postulated chiral inversion of D-dopa to L-dopa and the related mechanism, an enantiomeric separation method for D- and L-dopa using HPLC was first established. Then, rat kidney homogenates containing D-dopa or L-dopa were incubated and subjected to HPLC to detect traces of respective enantiomer generation. The mechanism of the chiral inversion of d-dopa was explored by direct measurement of the production of L-dopa in kidney homogenates. D-dopa incubations containing different concentrations of an inhibitor of D-amino acid oxidase (DAAO) and an inhibitor of dopa transaminase were measured for L-dopa generation using HPLC. The role of DAAO in the chiral inversion of D-dopa to L-dopa was further investigated by using purified DAAO and mutant ddY/DAAO- mouse kidney lacking DAAO activity. 3. In rat kidney homogenate, D-dopa was, indeed, converted to L-dopa, whereas L-dopa was not converted to D-dopa. Sodium benzoate, a selective inhibitor of DAAO, blocked L-dopa generation in a concentration-dependant manner. In contrast with kidney homogenates of wild-type ddY/DAAO+ mice, those of mutant ddY/DAAO- mice lacking DAAO activity did not convert D-dopa to L-dopa unless exogenous DAAO protein was added. Conversely, when carbidopa, an inhibitor of dopa transaminase, was added to the homogenates, significant inhibition of L-dopa production was noted. 4. These results prove the proposal that d-dopa undergoes unidirectional chiral inversion and further suggest that D-dopa is first oxidatively deaminated by DAAO to its alpha-keto acid and then transaminated by dopa transaminase to L-dopa.

Animals↗
PubMed1989

Variations in serum sorbitol dehydrogenase, aspartate transaminase, and isoenzyme 5 of lactate dehydrogenase activities in horses given carbon tetrachloride.

Seven horses were given 0.5 mg of carbon tetrachloride/kg of body weight via a nasogastric tube. Subsequent hepatocellular damage was monitored by serum enzyme determinations of sorbitol dehydrogenase, isoenzyme 5 of lactate dehydrogenase, and aspartate transaminase activities. Creatinine kinase activity was evaluated as an indicator of muscle cell damage. Sorbitol dehydrogenase, isoenzyme 5 of lactate dehydrogenase, and aspartate transaminase activities were significantly (P less than 0.05) increased by 24 hours after carbon tetrachloride administration. Isoenzyme 5 of lactate dehydrogenase and sorbitol dehydrogenase activities returned to baseline several days before aspartate transaminase activity returned to baseline. Creatine kinase activity remained unchanged.

Animals↗
PubMedDate not supplied

Urinary aspartate transaminase (AST) activity and detection of its inhibitors in normal urine.

Urinary aspartate-transaminase activity in the whole urine was found to be mean +/- S.D. = 8.46 +/- 0.69 l.U/l when measured immediately after urine collection. About 50% loss in enzyme activity was observed after 18 hours dialysis. An overall 176% increase in enzyme activity followed by Sephadex G-25 (fine) whole urine fractionation and a highly significant (P less than .001) partial inhibition by earlier Sephadex fractions and maximum inhibition by earlier Sephadex fractions and maximum inhibition of enzyme by fraction 7 have suggested the presence of both high and low molecular weight urinary inhibitors of aspartate-transaminase. Urea and ammonia presence and inhibitor activity in fraction 6 to 8 bear a close parallelism; both the substances produced 31% inhibition of partially purified goat liver GOT at concentrations approximating normal human urine. Therefore, low enzyme activity and its substantial loss in the whole urine and during dialysis may be due to the concomitant inhibitory effects of urea, ammonia and unidentified nature of high molecular weight substance(s). The present method may be effective in separating inhibitors and overcoming the disadvantages of dialysis in determining true urinary aspartate-transaminase activity.

Adult↗
PubMed1994

Determination of free D-amino acids with a bacterial transaminase: their depletion leads to inhibition of bacterial growth.

A general procedure is described to determine the common free D-amino acids except D-proline in mixtures that also contain L-amino acids. The system employs exogenous pure bacterial D-amino acid transaminase coupled with 2-oxohexanoate, which accepts the amino group from D-amino acids to form D-norleucine. This amino acid is readily quantified by amino acid analysis since it elutes in a position not occupied by any of the common amino acids. Formation of norleucine denotes the presence of some D-amino acid(s) whose identity can be established by a corresponding decrease in the susceptible amino acid(s) after treatment. The utility of the procedure is demonstrated by determination of the amounts of free D-alanine and free D-glutamate in extracts of Escherichia coli JM-103 grown on minimal medium; D-alanine was the major D-amino acid. By the same principle, 2-oxohexanoate through coupling with endogenous bacterial D-amino acid transaminase is shown to be capable of inhibiting the growth of E. coli by depleting it of the D-alanine and D-glutamate.

Amino Acids↗
PubMed1975

Transaminase level (GOT, GPT) in rats under treatment with diethylnitrosamine.

Transaminase levels (GOT, GPT) of Sprague-Dawley-rats were not increased during long-term oral application of diethylnitrosamine (DENA) in doses of 0.1 and 3.0 mg/kg/day respectively. Only rise of the daily dose to 12.0 mg/kg/ (4% of LD50) resulted in a significant increase of enzymatic activities after 2-3 months of treatment. By the determination of transaminases the process of liver cancerization cannot be discovered. The present method is also too insensitive to indicate the formation of smaller quantities of nitroso compounds from their precursors (amines plus nitrite) in vivo.

Alanine Transaminase↗
PubMed1980

Two forms of GABA transaminase in pig brain: purification and properties.

Two forms of GABA transaminase which could be distinguished by ion-exchange chromatography have been separated and purified in pig brain. The two forms have different Km values for alpha-ketoglutarate and show different degrees of inhibition by various salts. Although the two forms are separable, they have identical antigenic properties, pH optima, and NH2 terminal amino acid composition, and they appear to be of the same molecular size. The biological significance or the relationship between multiple forms of GABA transaminase is not yet understood.

4-Aminobutyrate Transaminase↗
PubMed1981

induction and derepression of arginase and ornithine transaminase in different strains of Saccharomyces cerevisiae.

The syntheses of arginase and ornithine transaminase were studied in two strains of Saccharomyces cerevisiae, viz. strain B and strain alpha-sigma 1278b. Derepression of both enzymes during nitrogen starvation was shown only by strain B, non-specific induction of arginase only by strain alpha-sigma 1278b. This different response of both strains studied reveals substantial differences in the regulation of enzyme synthesis among yeast strains of one and the same species. The specific enzyme activities observed in chemostat cultures with arginine as the nitrogen source and different sugars, at variable carbon to nitrogen ratios, did not indicate the involvement of carbon catabolite repression in the regulation of arginase and ornithine transaminase syntheses. Specific arginase activities observed in the continuous cultures varied widely and did not show a correlation with the intracellular arginine concentration. Extracellular steady-state arginine concentrations higher than about 1.0 mM, in addition to abundant energy supply, were found to be required for high production of arginase. It is suggested that, besides intracellular arginine, extracellular arginine may provide an induction signal necessary for full-scale induction of arginase synthesis. A possible intermediary role of arginine permeases or of other membrane proteins is discussed.

Arginase↗
PubMed1976

Improved histological localization of GABA-transaminase activity in rat cerebellar cortex after aldehyde fixation.

A method for the chemical fixation of the enzyme GABA-transaminase in nervous tissue is described. It is shown that after perfusion with a formaldehyde/glutaraldehyde fixative, activity of the enzyme in cerebellar cortex is demonstrable whilst cellular morphology is preserved. Results from the improved technique have shown new sites of GABA-transaminase activity in cerebellar cortex. In view of these results a special function for glial cells in this area of brain has been suggested.

4-Aminobutyrate Transaminase↗
PubMed1997

Docosahexaenoic acid-rich fish oil does not enhance the elevation of serum transaminase and liver triacylglycerol induced by carbon tetrachloride in mice.

Carbon tetrachloride (CCl4) is metabolized to trichloromethyl radical and induces liver injury with elevated serum transaminase and increased hepatic triacylglycerols (TG). To answer the question whether dietary polyunsaturated fatty acids (PUFA) enhance free radical-mediated liver injury, a docosahexaenoic acid (DHA)-rich fish oil (FO) or a saturated and monounsaturated fatty acid-rich beef tallow diet was fed to mice for 4 wk and then CCl4 was administered. When thiobarbituric acid-reactive substances (TBARS) were measured in the absence of antioxidant the FO diet and CCl4 treatment markedly increased liver TBARS values synergistically, apparently supporting the interpretation that the highly autoxidizable DHA accelerates lipid peroxidation induced by CCl4. However,no such marked interaction was observed between diet and CCl4 treatment in liver TBARS values measured in the presence of an antioxidant in the assay mixtures as well as in conjugated diene contents. Furthermore, the FO diet did not enhance CCl4-induced elevation of serum transaminase but lowered liver TG levels. The proportion of DHA,the most easily autoxidizable among common PUFA, was increased but those of eicosanoid precursors were decreased in liver phospholipids by CCl4 treatment, possibly reflecting the inflammation-related mobilization of eicosanoid precursors but not lipid peroxidation. These results indicate that dietary enrichment with DHA does not enhance CCl4-induced liver injury through the so-called free radical-mediated propagative autoxidation of DHA in mice.

Alanine Transaminase↗
PubMed1978

Comparison of the structural characteristics of the 4-aminobutyrate:2-oxoglutarate transaminases from rat and human brain, and of their affinities for certain inhibitors.

4-Aminobutyrate:2-oxoglutarate (4-aminobutyrate:2-oxoglutarate amino-transferase, EC 2.6.1.19) from human brain has been purified 2500-fold with respect to the initial homogenate. The enzyme, which appears to be pure by polyacrylamide gel electrophoresis, N-terminal analysis and immunodiffusion, was compared to rat brain 4-aminobutyrate transaminase, purified to the same extent in an earlier study [15]. The two enzymes, which have approximately the same molecular weight, show large differences in their tryptic fingerprints and in the peptides produced by cyanogen bromide cleavage. The Km values (limit) for 4-aminobutyrate are different, the human enzyme having four times greater affinity for this substrate. A series of branched-chain fatty acids (including n-dipropylacetate), which are structural analogues of 4-aminobutyrate and inhibit rat brain 4-aminobutyrate transaminase, are less powerful inhibitors of the human enzyme.

4-Aminobutyrate Transaminase↗
PubMed1982

A histochemical study of GABA-transaminase in the efferents of the pallidum.

Kainic acid lesions of the globus pallidus reduce the histochemically detectable GABA-transaminase activity in the ipsilateral subthalamic nucleus. A similar decrease in enzyme activity occurs in the lateral habenula following lesions of the entopeduncular nucleus. Previous results on the localization of GABA-transaminase in efferents of the striatum indicated that such histochemistry may be a useful adjunct for the demonstration of GABA pathways. The present data are consistent with some previous literature indicating that these two pallidal efferents may contain GABA.

4-Aminobutyrate Transaminase↗
PubMed1977

L-Ornithine-ketoacid-transaminase deficiency in cultured fibroblasts of a patient with hyperornithinaemia and gyrate atrophy of the choroid and retina.

L-Ornithine-ketoacid-transaminase deficiency was established in cultured fibroblasts obtained from a patient with hyperornithinaemia (mean ornithine level in serum approximately 100 mumol/l) and gyrate atrophy of the choroid and retina. The deficiency was found both the L-ornithine concentrations of 3.0 mM (about twice the KM value) and 12 mM, indicating that the enzymic defect was not due to a decreased affinity for this substrate. The reliability of the colorimetric assay of ornithine-ketoacid-transaminase activity was established radiochemically. Performance of the radiochemical assay revealed the presence of an impurity in the substrate DL-[2-14C]ornithine - HCl being a strong inhibitor of the enzyme. The passage level and the subcultivation time of the fibroblasts did not influence the enzymic activity.

Amino Acids↗
PubMed1983

Effect of phenolic compounds on in vivo activity of transaminases in certain tissues of the fish, Notopterus notopterus.

Chronic effects of phenol (P), 2,4-dinitrophenol (DNP), and pentachlorophenol (PCP) individually and in three combinations, viz. (PCP + DNP)/P (highly antagonistic), (DNP + P)/PCP (additive), and (P + DNP)/PCP (highly synergistic) on in vivo activity of glutamic oxalacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) in brain, liver, kidney, and gills of Notopterus notopterus were studied at subacute levels (1/10, 1/15, and 1/20 of 96-hr LC50) following exposure for 15 and 30 days. Significant stimulation in activity of GOT and GPT was observed in all the tissues at different concentrations of phenolic compounds after both the time intervals. However, stimulation in activity of both GOT and GPT was maximum (140.67% in GOT, 142.68% in GPT) in liver at 1/10 concentration of the (P + DNP)/PCP combination after 30 days, but minimum in gills, in case of GOT (17.29%) at 1/20 of P after 15 days and in case of GPT (7.68%) at 1/20 of the (PCP + DNP)/P combination after 30 days. Stimulatory effect of phenolic compounds on the activity of these enzymes indicates possibly the increased conversion of amino acids into keto acids and vice versa, thus resulting in the disturbance of protein metabolism.

2,4-Dinitrophenol↗
PubMed1980

The pharmacohistochemical demonstration of GABA-transaminase.

A method for the histochemical demonstration of cells with the capacity to synthesize the enzyme GABA-transaminase is described. Intraventricular injection of ethanolamine-O-sulfate irreversibly inhibits brain GABA-transaminase activity. Within 17 h after the injection sufficient new enzyme is synthesized to allow histochemical visualization of positive soma against unstained neuropil. The implications of this technique for the anatomy of GABA systems is discussed.

4-Aminobutyrate Transaminase↗