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PubMed1979

The effect of pre-incubation and direct procedure for the alanine transaminase assay in two kits compared.

The kinetic measurement of serum alanine transaminase was carried out on two enzyme kits (Roche and Calbiochem), done as a direct method and a pre-incubation method. Variable results from commercial control sera and patient sera by these four procedures were obtained. Pre-incubation enzyme values were generally lower than the direct values (mean difference 10%), but there were marked differences between the results from the two kits. This finding has important significance especially for laboratories participating in external QC Programmes. Frequent precision checks of the method and a local reference range are therefore necessary.

Alanine Transaminase↗
PubMed1985

Affinity chromatography of B6-vitamin-dependent enzymes: purification of pig-heart branched-chain amino acid transaminase.

Pig-heart branched-chain amino acid transaminase (EC 2.6.1.42) was purified to near homogeneity with a yield of 27%. A prepurification was performed by heat treatment, gel chromatography and DEAE-Sepharose methods. For the final step, several affinity gels were tested and the one containing cycloserine coupled to CNBr-activated Sepharose 4B was selected. This effected an additional five-fold purification with a yield of 60%. The present affinity results are compared with corresponding studies with other aminotransferases in an attempt to find possible universal techniques for their purification.

Animals↗
PubMed2000

Hepatitis C virus infection and alanine transaminase levels in the general population: a survey in a southern Italian town.

BACKGROUND/AIM: The aim of the study was to estimate the prevalence, risk factors and genotype distribution of hepatitis C virus (HCV) in the general population older than 5 years of age in a southern Italian town. The positive predictive value of alanine transaminase (ALT) screening in identifying HCV positive subjects was also assessed. METHODS: Cluster random sampling from the census of the general population was used. ELISA and RIBA tests assessed the presence of anti-HCV; nested reverse transcription polymerase chain reaction (RT-PCR) was used to identify HCV-RNA; genotyping was performed by INNO-LIPA III. The association linking anti-HCV seropositivity with potential risk factors was assessed by multiple logistic regression analysis. RESULTS: Among the 488 subjects enrolled, 79 (16.2%) were anti-HCV positive. The prevalence increased from 1.2% in subjects 6-29 years of age to 42.1% in those > or = 60 years. Forty percent of these positive subjects also had abnormal ALT level and 54.4% were HCV RNA positive by PCR. The positive predictive value of the ALT test in identifying anti-HCV positive subjects was 65%; however, it was 46.7% in subjects younger than 60 years of age and 90.5% in those 60 or older. Genotype 1b was detected in 74% of subjects, type 2c in 23.3%, and type 1a in 2.3%. The only two variables significantly associated with HCV seropositivity in multivariate analysis were age older than 45 years (O.R. 8.5; CI 95%=3.0-24.1) and past use of glass syringes (O.R. 3.4; CI 95%=1.5-7.6). CONCLUSIONS: These findings confirm that HCV infection is endemic in southern Italy, particularly among the elderly. Percutaneous exposure, such as injections with nondisposable, multiple-use, glass syringes used in the past for medical purposes may have played a major role in the spread of HCV infection. ALT screening is not useful in detecting HCV positive subjects in the general population, particularly among subjects who could benefit from antiviral therapy.

Adolescent↗
PubMed2000

Interleukin 1beta and GABA-transaminase activity in rat thymus.

The occurrence and distribution of 4-aminobutyrate:2 oxoglutarate transaminase (GABA-t) activity were examined in the rat thymus of normal and immunostimulated rats using biochemical and histoenzymatical methods. Specific GABA-t reactivity was confined primarily to the arteries and, to a lesser extent, to the veins. Only a few activities could be observed in association with the subcapsular and medullar part of the parenchyma and nerve fibers. GABA-t was considered a linking enzyme between the immune and the nervous system and it was studied with the aim of analyzing the relationships between these two systems. Our findings indicate that the GABA-t activity in the thymus is specifically located in the wall of the blood vessels. Moreover, our results demonstrate the presence of a GABA-t activity in the peripheral blood vessels. Treatment with interleukin 1beta induces an increase of protein content of the amounts of GABA-t biochemically assayed and of the levels of histoenzymatically stained GABA-t. Furthermore, staining of the different structures of the thymus in treated or untreated rats shows that the significant modifications concern the parenchyma, the structures resembling nerve fibers and finally, the whole thymus. On the contrary, the highest activity of the GABA-t is located in the walls of arteries, veins and lymphatic vessels.

4-Aminobutyrate Transaminase↗
PubMed2001

The alteration of gamma-aminobutyric acid-transaminase expression in the gerbil hippocampus induced by seizure.

It is well established that GABA degradation may play a key role in epileptogenesis. However, whether or not the expression of GABA-transaminase (GABA-T), which catalyzes GABA degradation and participates in the neuronal metabolism via GABA shunt, changes chronologically after on-set of seizure remains to be clarified. To identify the change of GABA-T expression in seizure, GABA-T expression in the gerbil hippocampus, associated with different sequelae of spontaneous seizures, was investigated. The distribution pattern of GABA-T immunoreactive neurons in the hippocampus between the seizure-resistant and pre-seizure group of seizure sensitive gerbils was similar. Interestingly, at 30 min postictal, the enhancement of GABA-T immunoreactivity in the perikarya was apparently observed. This contrasted with the decline in GABA-T immunoreactivity in the granular and pyramidal layer. At 12-24 h postictal, GABA-T immunoreactivity in the hilar neurons had declined significantly. However, the GABA-T immunoreactivity in the granular layer increased. These findings suggest that in the gerbil, the alteration in GABA-T expressions may play an important role in the self-recovery mechanism from seizure attack via both GABA degradation and regulation of neuronal metabolism.

4-Aminobutyrate Transaminase↗
PubMed1998

Expression of GABA transaminase immunoreactivity in interneurons of the rat neostriatum.

Immunoreactivity for gamma-aminobutyric acid transaminase (GABA-T), a degradation enzyme for GABA, was localized by immunocytochemistry in the rat neostriatum and the globus pallidus using a monoclonal antibody. Immunoreactivity for GABA-T was found primarily in interneurons and in the neuropilar elements in the neostriatum. Many of GABA-T-immunoreactive neurons were found to display parvalbumin immunoreactivity. This indicates many of the GABA-T-immunoreactive neurons are striatal GABAergic interneurons. Occasionally, GABA-T-immunoreactive glial cells were found. In the globus pallidus, many pallidal neurons also displayed GABA-T immunoreactivity and many of the immunoreactive neurons were seen to express parvalbumin immunoreactivity. Immunoreactivity for GABA-T was also detected in the neuropil of the globus pallidus. The present results indicate the GABAergic interneurons in the neostriatum and a subpopulation of pallidal neurons play an important role in metabolic degradation of GABA in the basal ganglia.

4-Aminobutyrate Transaminase↗
PubMed2000

gamma-aminobutyric acid-transaminase activity in the human thymus after administration of interferons.

The purpose of this article is to study the amounts of gamma-aminobutyric acid-transaminase (GABA-t) during immune response in the human thymus. GABA-t was studied by biochemical and histochemical methods in 7 immunostimulated (treated) and 7 non-immunostimulated (untreated) patients (4 young adult, age range: 24-36 years; 3 older adult, age range: 56-66 years). Immunostimulation was performed using interferon drugs for 6 months. After the histoenzymatic staining of GABA-t activity, the slides containing the samples of thymus of treated and untreated patients underwent quantitative analysis of images. The present results provide direct evidence that the immune response increases the level of GABA-t contained in vessels, parenchyma and nerve fibers of the thymus. Treatment with interferon is also capable of increasing the protein content of the thymus. The biochemical data together with the histoenzymatic results provide evidence for a localization of GABA-t in the thymic gland. Moreover, gamma-aminobutyric acid can be considered as one of the linking molecules between the immune and nervous functions of the human thymus.

4-Aminobutyrate Transaminase↗
PubMed1999

Occurrence of gamma-aminobutyric acid-transaminase activity in nerve fibers of human thymus.

The specific localization of gamma-aminobutyric acid-transaminase (GABA-t) in the thymus of young and elderly men was studied. Our results show a specific vascular localization of GABA-t in the human thymus, and deal with the amount and distribution of GABA-t and its changes with age. Samples of human thymus were harvested throughout of 12 autopsies in infants (n = 3), as well as young (n = 3), adult (n = 3) and elderly (n = 3) men. Histologic staining of the human thymus was performed with eosin-orange, while histologic staining of nerve fibers was performed with the Bodian method. Histochemical and biochemical demonstration of GABA-t, including protein dosage, was performed by the methods of Van Gelder and Jung, respectively. Finally, quantitative analysis of images was performed. Staining with eosin-orange reveals the micro-anatomical details of the thymic micro-environment. The Bodian method shows the nerve fibers and neurofibrils. Histochemical staining for GABA-t shows an increase of this enzyme with age and a marked localization in the nerve fibers of the thymus in infant, young, adult, and elderly men, as well as specific vascular localization of this enzyme. These biochemical data are in accordance with the histoenzymatic results and confirm all of our previous observations. Finally, quantitative analysis of images performed on slices let us confirm all the morphological changes induced by age. We can conclude that GABA is an inhibitory neurotransmitter of the human thymus, while GABA-t plays an important role in GABA metabolism.

4-Aminobutyrate Transaminase↗
PubMed2000

Elevation of the gamma-aminobutyric acid transaminase expression in the gerbil CA1 area after ischemia-reperfusion damage.

gamma-Aminobutyric acid-transaminase (GABA-T) plays an important role in the metabolism of GABA, particularly in the neurons or glial cells. The present study was undertaken to determine the alteration of GABA-T expression in the gerbil hippocampus after ischemia-reperfusion. In the sham, GABA-T(+) neurons were scattered in the hippocampus proper and dentate gyrus. The intensity of the GABA-T immunoreactivity had nearly disappeared in the interneurons at 12 h after ischemia. In contrast, 24 h post-ischemia the dramatic augmentation of GABA-T immunoreactivity in the pyramidal cells was observed in the CA1 area but not in the CA2 or CA3 areas. Forty-eight hours after ischemia-reperfusion, its immunoreactivity was preserved in the CA1 neurons. These results suggest that the over-expression of GABA-T in the CA1 area may be related to delayed neuronal death after ischemia-reperfusion insult.

4-Aminobutyrate Transaminase↗
PubMed1998

Localization of GABA transaminase immunoreactivity in the rat substantia nigra pars reticulata.

Precise cellular localization of gamma-aminobutyric acid transaminase (GABA(T)), a degrading enzyme for the neurotransmitter GABA, was determined in the rat substantia nigra (SN) by immunocytochemical experiments using a recently developed monoclonal antibody. In order to characterize the GABA(T)-immunoreactive neurons, double immunocytochemistry was also performed using tyrosine hydroxylase (TH) as a neurochemical marker for dopaminergic neurons in the substantia nigra pars compacta (SNc). Immunoreactivity for GABA(T) was primarily localized in perikarya of the SN. There were only a few GABA(T)-immunoreactive neurons found to display TH immunoreactivity. Most of the GABA(T)-immunoreactive neurons were then identified as reticulata neurons. These results indicate that reticulata neurons are the major nigral neurons that express GABA(T) immunoreactivity and there may be functional compartmentalization of the GABA metabolism in the rat substantia nigra pars reticulata (SNr).

4-Aminobutyrate Transaminase↗
PubMed2002

Transaminase and alkaline phosphatase activity in the serum of burn patients treated with highly purified tannic acid.

The effects of local treatment with highly purified tannic acid (HPTA) on serum transaminase and alkaline phosphatase activity in burn patients were studied, retrospectively. Temporary elevations in the activity of gamma-glutamyl transferase (GGT), aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and alkaline phosphatase (AP) were observed in both HPTA-treated patients and their matched controls. No statistically significant difference was found between the two patient-groups with respect to the mean enzyme activities, calculated as the areas under the curve between 5 and 15 days post-burn (PBD). These results seem to indicate that HPTA does not cause hepatotoxicity, at least when applied to a burned area corresponding to approximately 10% of the total body surface. This is in agreement with the widespread and frequent use of HPTA in the food, cosmetic and pharmaceutical industries.

Administration, Topical↗
PubMed2002

Use of a GABA-transaminase agonist for treatment of infantile autism.

This paper describes the use of a GABA-transaminase agonist for the treatment of infantile autism. An approximate one third reduction of GABA and ammonia levels for an autistic patient with noticeable improvement of verbal/language skills and a reduction of repetitious ritualistic self-stimulatory behavior (stimming) was observed. A reduction of the plasma GABA (by administrating a GABA-T agonist, Imipramine) probably results in more axon(s)-to-oligodendrocyte signaling in the corpus callosum and it is postulated that this could result in a reduction of the autistic features for the patient.

4-Aminobutyrate Transaminase↗
PubMed2000

A role of nitric oxide as an inhibitor of gamma-aminobutyric acid transaminase in rat brain.

The present study has been aimed to investigate the effect of nitric oxide (NO) on the concentration of gamma-aminobutyric acid (GABA) in rat brain. The concentrations of GABA and glutamate and the activities of glutamic acid decarboxylase (GAD) and gamma-aminobutyric acid transaminase (GABA-T) were determined in groups of animals 5 and 30 min after intraperitoneal injection of a NO-increasing dose (1,000 mg/kg) of its precursor, L-arginine and a dose (50 mg/kg) of N-nitro-L-arginine methyl ester (L-NAME) that inhibits NO synthesis from L-arginine. L-arginine-induced elevation of NO concentration was accompanied by an increased concentration of GABA in the brain. GABA-T activity was inhibited in these animals. NO-decreasing action of L-NAME coincided with a reduction in the concentration of GABA and an enhancement of GABA-T activity. Both L-arginine and L-NAME did not alter the activity of GAD and the concentration of glutamate. An interpretation of these data suggests that NO has a GABA-T-inhibiting role in the brain.

4-Aminobutyrate Transaminase↗
PubMedDate not supplied

Branched-chain transaminase and keto acid dehydrogenase activities in burned rats: evidence for a differential adaptation according to sex.

Female and male rats show differences in nitrogen metabolism after trauma, and the contribution of the branched-chain amino acid oxidizing pathway following thermal injury was evaluated. Female and male rats were subdivided into baseline, burned and unburned, pair-fed groups. Burned and pair-fed rats were sacrificed on days 1, 2, and 3 postburn, and branched-chain amino acid transaminase (BCTA), branched-chain alpha-keto acid dehydrogenase (BCKDH) activated and total, and succinate dehydrogenase (SDH) activities were measured in red and white muscle and in liver, BCTA was not measured in liver. Baseline and pair-fed groups had similar enzyme activities. Changes following thermal injury were: (1) elevated SDH in all tissues for both sexes; (2) increased BCTA activity in red and white muscles from male rats; and (3) increased percentage of activated BCKDH in red and white muscles on days 2 and 3 for male rats. All other activities were unchanged. These findings agree with previous post trauma differences in urinary nitrogen losses in female and male rats. The results show that the enzymes for oxidation of the branched-chain amino acids in males respond to injury while those do not in females.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed2003

Uptake of GABA and activity of GABA-transaminase in platelets from epileptic patients.

The aim of the present study was to assess the activity of GABA-transaminase (GABA-T) and the kinetic parameters of GABA uptake in platelets from patients with distinct epileptic syndromes. We studied 14 patients with juvenile myoclonic epilepsy (JME), 19 patients with refractory localization-related epilepsy (RLE) and 20 healthy volunteers who were matched for age and sex. Acute effects of valproate (VPA) and lamotrigine (LTG) on the uptake of GABA and the activity of GABA-T in platelets in vitro were also analyzed. The mean activity of GABA-T in JME patients was significantly higher than in control subjects, whereas RLE patients did not significantly differ from controls. The capacity of GABA uptake was least in JME patients, intermediate in RLE patients and highest in controls. In vitro VPA (concentrations 150-1200 microM) or LTG (concentrations 1-100 microM) had no significant effects on GABA uptake. Our results indicate marked differences in the platelet uptake of GABA and the activity of catabolic enzyme GABA-T between patients with generalized and localization-related epileptic syndromes. The observed peripheral alterations may indicate an impairment in the function of brain GABAergic systems.

4-Aminobutyrate Transaminase↗
PubMed1997

Basic aspects of GABA-transmission in alcoholism, with particular reference to GABA-transaminase.

Neuronal dysfunction is the neurobiological basis for alcoholic behaviour, and ethanol craving seems related to hypofunction of the GABA-ergic activity. Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS). In several studies, GABA has been shown to be an important target of ethanol in the CNS, partly, as a consequence of damage to membrane-bound enzymes and receptors. GABA is involved in mediating pre- and post-synaptic inhibition of neuronal activity. It is speculated that the initial excitatory effects of ethanol may be due to inhibition of GABA-ergic activity whereas the sedative effects of the higher doses may be mediated by the activation of this inhibitory system. In the CNS, GABA is synthesised from glutamic acid by the enzyme glutamate decarboxylase (GAD) and catabolized into succinic semialdehyde by the enzyme GABA-transaminase (GABA-T), which are pyridoxal phosphate (PLP) dependent enzymes. Platelet GABA-T was characterized as being similar to central GABA-T. Inhibition of GABA-T with certain potent and selective compounds markedly increases the levels of brain GABA. Experimentally, acute ethanol treatment does not alter GABA-T activity whereas chronic treatment produces an increase in the activity, though, with some reservations since a bimodal effect has been found in chronically ethanol-treated rats. Thus, as it will be discussed below, it may be suggested that GABA-T inhibitors (e.g. vigabatrin) could have a potential role in the treatment of alcoholism and in some of the problems of ethanol withdrawal and of other drugs of abuse. Related studies on metabolism and concentrations of GABA are also promising and show a greater increase in our understanding of the aetiology and treatment of ethanol dependence and withdrawal. In general, this article also reviews both the animal and clinical observations in the field of alcoholism with regard to the GABA system.

4-Aminobutyrate Transaminase↗
PubMed2001

[Differential diagnosis of elevated transaminases].

Elevated serum levels of transaminases must always be considered as an abnormal finding. Drugs and toxins must be eliminated first as possible hepatotoxic agents or co-factors. Antiviral hepatitis A IgM determination is the first test to perform. However, other viruses with spontaneous benign courses are the most frequent cause. Only if the initial presentation is severe, or if liver tests remain abnormal after several weeks, can other rare diseases be sought. Liver biopsy is rarely necessary to reach a diagnosis.

Biopsy↗
PubMed2001

Dehydrogenases and transaminases in asymmetric synthesis.

Improved stereoselectivity in dehydrogenase-mediated reductions has been achieved by rationally designed gene overexpression and knockouts in Saccharomyces cerevisiae cells and by isolating and characterizing novel dehydrogenases from other organisms. Transaminases have been used to prepare unnatural amines and amino acids in good yields, particularly when the equilibria are shifted by selective product removal.

Amines↗