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PubMed2004

Scrutiny of the glutamine-fructose-6-phosphate transaminase 1 (GFPT1) locus reveals conserved haplotype block structure not associated with diabetic nephropathy.

Glutamine-fructose-6-phosphate transaminase 1 (GFAT) is the rate-limiting enzyme of the hexosamine pathway that has been implicated in the pathogenesis of diabetic nephropathy. As such, we hypothesized that GFPT1, which encodes for GFAT, may confer genetic susceptibility to this complication among Caucasians. Screening of all known functional regions of GFPT1 revealed six single nucleotide polymorphisms (SNPs) that were located in the promoter, introns, and 3' untranslated region. The approximately 60 kb GFPT1 locus was encompassed in a single conserved haplotype block, and two tagging SNPs were sufficient to capture >90% of the haplotype diversity. Analysis of these SNPs in a case-control study made up of type 1 diabetic subjects (324 case subjects with diabetic nephropathy and 289 control subjects with normoalbuminuria despite >15 years of diabetes) revealed no significant association even after stratification by sex, diabetes duration, glucose control, and blood pressure. Similar results were obtained among type 2 diabetic subjects (202 case and 114 control subjects). Genetic variation in GFPT1 is thus unlikely to have a major impact on susceptibility to diabetic nephropathy.

3' Untranslated Regions↗

PubMed1980

Effect of voluntary exercise and dietary protein levels on the activity of serum glutamic pyruvic transaminase and the morphological picture of liver in mice.

In the present investigation, effects of voluntary exercise on serum glutamic pyruvic transaminase (SGPT) activity and histological alterations of liver tissue of mice fed 4%, 6% and 20% casein diet were examined. AGPT activity showed decreasing values accompanied by dietary protein level increases. In 4% casein diet groups, SGPT activity of the exercise group was markedly lower than that of the non-exercise group. Furthermore, there was a negative correlation between SGPT and LCAT activity. In histological evaluation, the non-exercise group on 4% casein diet revealed diffuse fatty degeneration of the liver, but the exercise group did not show such changes.

Alanine Transaminase↗

PubMed1996

Dietary wheat gluten alleviates the elevation of serum transaminase activities in D-galactosamine-injected rats.

The effects of dietary protein on the elevation of activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in D-galactosamine-injected rats were investigated. The rats fed with experimental diets containing test protein sources for 2 weeks were injected with D-galactosamine (0.8 g.kg-1 body weight). The activities of AST and ALT in serum were assayed after 20 h. According to the results, these enzyme activities in the rats fed 40% casein diet were higher than those of 5, 10, or 20% casein groups. In the 40% gluten group, these enzyme activities were lower than in the 40% casein group. This difference was not considered to be caused by the deficit of L-lysine and L-threonine in gluten. The extent of the reduction of UTP and UDP-glucose in liver by D-galactosamine was almost the same in the 40% gluten and 40% casein groups. These results suggest that levels and quality of dietary protein affect the susceptibility of animals to the hepatotoxin D-galactosamine and dietary gluten was found to alleviate the elevation of serum transaminases in rats by the drug.

Alanine Transaminase↗

PubMed1992

Synthesis of a potential bifunctional mimic of transaminases.

As a potential bifunctional mimic of transaminases 3,7-dimethyl-10-[3-(4- aminomethyl-5-hydroxy-6-methyl-3-pyridyl)propyl]-3,7,10- triazatricyclo[3.3.3.0(1,5)] undecane (I) has been synthesized by attaching 3,7-dimethyl-3,7,10-triazatricyclo [3.3.3.0(1,5)]undecane (II) to a pyridoxamine nucleus via an all-carbon chain. The chain length between the pyridine ring and II is restricted to three atom units so that the possibility for II to act bifunctionally during the transamination is maximized. In its protonated form, the nitrogen closest to the pyridine ring cannot deliver the proton intramolecularly to the alpha-carbon of the developing amino acid. To make the synthetic route generally applicable, introduction of the side-arm base is arranged at a later stage of the synthesis so that different di- or poly-amines can easily be used in place of II to prepare other target molecules that might possess bifunctional catalytic activity. This arrangement also greatly reduces the polarity and water-solubility of the intermediates and the purification of these compounds thus becomes much easier. The method of introducing the amino functionality at the C-4 methylene group described herein provides an alternative to that currently in use (reduction of oximes).

Aza Compounds↗

PubMed1998

[Characteristics of the carriers of antibodies to hepatitis C virus with normal transaminases levels in HIV infected patients].

BACKGROUND: To know the characteristics of the carriers of antibodies to hepatitis C virus (HCV) with persistently normal transaminases levels ("carriers") in coinfected with HIV, the incidence of the real viral activity and the factors that could determine it. PATIENTS AND METHODS: We analyzed 114 patients with criteria for chronic hepatitis C, 41 with detectable antibodies (anti-HCV), but without chemical evidence of a deteriorations of the liver function, all of them infected with HIV. In 6 patients was possible to determine the genotype of the HCV (INNO-LiPA HCV Innogenetics. Belgica) and in 32 the HCV-RNA (Amplicor HCV Roche Diagnostics). We compared the characteristics that could be differential between both groups, investigating the possible factors that could define the group of "carriers" with detectable viral activity. RESULTS: From the 32 "carriers" in which we could determine the HCV-RNA, 15 (46.8%) had a positive result. The incidence of women in the "carriers" group was higher (41.4% vs 22.8%) (p < 0.05). The serum levels of gammaglobulin (gr/dl) was higher in the chronic hepatitis group (2.23 +/- 0.6 vs 1.9 +/- 0.5) (p < 0.01); however, these levels were higher for the 15 patients RNA (-) patients (2.19 +/- 0.7 vs 1.66 +/- 0.41) (p < 0.01). The genotype distribution of HCV found in the "carriers" group with detectable viremia was: genotype 1(5 patients), subtype la (3 patients), subtype lb (2 patients) an genotype 3 (3 patients). There was no significant difference with respect to age, sex, degree of immunosuppression or the length of the infection with HCV. CONCLUSIONS: Approximately half of our "carriers" of anti-HCV without evidence of changes in the liver function, infected with HIV, show detectable viremia and so probably liver biopsy would be indicated. Women are more often "carriers" and the high levels of gammaglobulin could define the existence of a real viral activity.

Adult↗

PubMed1999

The irreversible gamma-aminobutyric acid (GABA) transaminase inhibitor gamma-vinyl-GABA blocks cocaine self-administration in rats.

gamma-Vinyl gamma-aminobutyric acid (GABA) (GVG) is an irreversible inhibitor of GABA transaminase, the primary enzyme involved in GABA metabolism. Acute administration of GVG increases brain GABA levels and blocks cocaine-induced locomotor activity, cocaine-induced lowering of brain stimulation reward thresholds, and cocaine-induced conditioned place preference. To further evaluate the effects of GVG on cocaine-induced reward, we examined its effects on cocaine self-administration in male Wistar rats on fixed ratio 5 and progressive ratio schedules of reinforcement. Additionally, the effects of GVG on operant responding for a food reward were examined on the same two schedules to determine whether the effects of GVG were specific to cocaine reward or generalized to other types of reward. GVG dose dependently decreased responding for cocaine on both schedules of reinforcement, suggesting that GVG attenuated the reward value of the cocaine. Responding for food was also decreased by GVG, suggesting that the effects of increased GABA levels induced by GVG may have a general effect on central reward systems. Data from this and other studies indicate that GVG does not induce motor impairment, decrease spontaneous locomotor activity, or induce catalepsy. Taken together, these data suggest that increases in GABAergic activity induced by GVG have an attenuating effect on centrally mediated reward systems and that the GABA system may be a useful target in the development of new therapeutic strategies for cocaine addiction.

4-Aminobutyrate Transaminase↗

PubMed1999

Asymmetric synthesis of chiral amines with omega-transaminase.

The asymmetric synthesis of chiral amines using prochiral ketones was carried out with (S)-specific omega-transaminase (omega-TA) from Vibrio fluvialis JS17. This reaction is inhibited severely by both products, (S)-amine and deaminated ketone. In addition, thermodynamic equilibrium strongly favored the reverse reaction. L-Alanine proved to be the best amino donor based on easy removal of the products. Optimal pH of the reactions with both whole cells and cell-free extract was 7. Amino acceptor reactivities of ketone substrates and reaction profiles of the asymmetric synthesis showed that the initial rate as well as the reaction yield were lower when the resulting (S)-amine from a prochiral ketone substrate was a more reactive amino donor. The yield could be increased dramatically by removing pyruvate, which is a more inhibitory product than (S)-alpha-methylbenzylamine [(S)-alpha-MBA] when acetophenone and L-alanine are used as an amino acceptor and donor, respectively. The removal of pyruvate was carried out by incorporating lactate dehydrogenase (LDH) in cell-free extract or by using whole cells. The whole cell reaction yielded a much better result. When 25 mM benzylacetone and 30 mM acetophenone were used as an amino acceptor with 300 mM L-alanine, 90.2% and 92.1% of the reaction yields after 1 day were obtained with whole cells, respectively. Enantiomeric excesses of both (S)-alpha-MBA and (S)-1-methyl-3-phenylpropylamine [(S)-MPPA] were all above 99%.

Alanine↗

PubMed1999

Occurrence of GABA-transaminase in the thymus gland of juvenile and aged rats.

The occurrence and distribution of GABA-transaminase (GABA-t) activity were examined in the thymus of juvenile, adult and aged rats, using enzyme-histochemical and biochemical methods. Quantitative image analysis showed that specific GABA-t reactivity was localized in the wall of the arteries and, to a lesser extent, to the veins. Only a low activity could be observed in association with the subcapsular and medullary part of the parenchyma of the thymus. Many structures resembling nerve fibers also showed low positive reactivity. Biochemical results gave the following decreasing order of GABA-t activity: arteries, veins, whole thymus and parenchyma. Histoenzymatic staining and related values of quantitative analysis of images, are in agreement with the biochemical results; moreover, they demonstrated that the intensity of histoenzymatic staining for GABA-t in thymus of rats strongly decreases with age. GABA-t in thymic tissue is concentrated in blood vessels and particularly in the arteries. Therefore, our findings do not support the earlier assumptions that GABA-t is exclusively concentrated in cerebral vessels. Moreover, the decrease of GABA-t activity during age in thymic tissues may be related to the decrease of thymic microvessels as consequence of the thymic involution. On the contrary, the thymic macrovessels show an elevated staining in all ages with an apparent increase due to the thymic involution.

4-Aminobutyrate Transaminase↗

PubMed2000

Bioactivation of selenocysteine Se-conjugates by a highly purified rat renal cysteine conjugate beta-lyase/glutamine transaminase K.

Selenocysteine Se-conjugates have recently been proposed as potential prodrugs to target pharmacologically active selenol compounds to the kidney. Although rat renal cytosol displayed a high activity of beta-elimination activity toward these substrates, the enzymes involved in this activation pathway as yet have not been identified. In the present study, the possible involvement of cysteine conjugate beta-lyase/glutamine transaminase K (beta-lyase/GTK) in cytosolic activity was investigated. To this end, the enzyme kinetics of 15 differentially substituted selenocysteine Se-conjugates and 11 cysteine S-conjugates was determined using highly purified rat renal beta-lyase/GTK. The results demonstrate that most selenocysteine Se-conjugates are beta-eliminated at a very high activity by purified beta-lyase/GTK, implicating an important role of this protein in the previously reported beta-elimination reactions in rat renal cytosol. As indicated by the rapid consumption of alpha-keto-gamma-methiolbutyric acid, purified beta-lyase/GTK also catalyzed transamination reactions, which appeared to even exceed that of beta-elimination. The corresponding sulfur analogs also showed significant transamination but were beta-eliminated at an extremely low rate. Comparison of the obtained enzyme kinetic data of purified beta-lyase/GTK with previously obtained data from rat renal cytosol showed a poor correlation. By determining the activity profiles of cytosolic fractions applied to anion exchange fast protein liquid chromatography and gel filtration chromatography, the involvement of multiple enzymes in the beta-elimination of selenocysteine Se-conjugates in rat renal cytosol was demonstrated. The identity and characteristics of these alternative selenocysteine conjugate beta-lyases, however, remain to be established.

Animals↗

PubMed1975

[Detection of hepatic lesions in patients with multiple injuries. Value of the determination of blood glutamo-pyruvic transaminase].

Serum glutamic pyruvic transaminase (S.G.P.T.) was measured in a series of 39 patients with multiple injuries in order to test its value in detecting liver lesion. An increase above five times the upper limit of the normal value was found in 15 out of the 20 patients having a liver injury and in all of those in whom S.G.P.T. was measured within the first 24 hours following the trauma. In contrast, a similar elevation was observed only in two out of the 19 patients without liver injury. It is suggested that S.G.P.T. determination should be routinely performed in patients with multiple injuries when abdominal signs are poor or concealed by associated lesions. A marked elevation of S.G.P.T. seems in any case suggestive enough to advise a liver arteriogram if hemodynamic conditions allow to perform it.

Abdominal Injuries↗

PubMed2001

GABA transaminase inhibition induces spontaneous and enhances depolarization-evoked GABA efflux via reversal of the GABA transporter.

The GABA transporter can reverse with depolarization, causing nonvesicular GABA release. However, this is thought to occur only under pathological conditions. Patch-clamp recordings were made from rat hippocampal neurons in primary cell cultures. Inhibition of GABA transaminase with the anticonvulsant gamma-vinyl GABA (vigabatrin; 0.05-100 microm) resulted in a large leak current that was blocked by bicuculline (50 microm). This leak current occurred in the absence of extracellular calcium and was blocked by the GABA transporter antagonist SKF-89976a (5 microm). These results indicate that vigabatrin induces spontaneous GABA efflux from neighboring cells via reversal of GABA transporters, subsequently leading to the stimulation of GABA(A) receptors on the recorded neuron. The leak current increased slowly over 4 d of treatment with 100 microm vigabatrin, at which time it reached an equivalent conductance of 9.0 +/- 4.9 nS. Blockade of glutamic acid decarboxylase with semicarbazide (2 mm) decreased the leak current that was induced by vigabatrin by 47%. In untreated cells, carrier-mediated GABA efflux did not occur spontaneously but was induced by an increase in [K(+)](o) from 3 to as little as 6 mm. Vigabatrin enhanced this depolarization-evoked nonvesicular GABA release and also enhanced the heteroexchange release of GABA induced by nipecotate. Thus, the GABA transporter normally operates near its equilibrium and can be easily induced to reverse by an increase in cytosolic [GABA] or mild depolarization. We propose that this transporter-mediated nonvesicular GABA release plays an important role in neuronal inhibition under both physiological and pathophysiological conditions and is the target of some anticonvulsants.

4-Aminobutyrate Transaminase↗

PubMedDate not supplied

Frequency of hepatitis C virus antibodies and elevated serum alanine transaminase levels in Ghanaian blood donors.

The objective of the study was to determine the frequency of Hepatitis C Virus (HCV) positivity in blood donors and investigate the possibility of using serum alanine transaminase (ALT) elevation as a surrogate marker. Blood samples from 1300 healthy blood donors were screened for HCV antibodies by an ELISA technique. The serum ALT was also assayed in 725 of them. 68 (5.2%) were positive for HCV antibodies. In the ALT assay 23 (3.2%) had elevated values and only 13 of this number had ALT values of 80 I.U and above. Only two positive HCV donors had elevated serum ALT. It is concluded that 5.2 per cent of blood donors had HCV antibodies and ALT assay cannot be used as a surrogate marker.

Alanine Transaminase↗

PubMed2001

Comparative studies on the GABA-transaminase immunoreactivity in rat and gerbil brains.

Gamma-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the central nervous system (CNS). Degradation of GABA in the CNS is catalyzed by the action of GABA transaminase (GABA-T). However, the neuroanatomical characteristics of GABA-T in the gerbil, which is a useful experimental animal in neuroscience, are still unknown. Therefore, we performed a comparative analysis of the distribution of GABA-T in rat and gerbil brains using immunohistochemistry. GABA-T immunoreactive neurons were observed in the regions which contained GABAergic neurons of both animals: corpus striatum; substantia nigra, pars reticulata; septal nucleus; and accumbens nucleus. GABA-T + neurons were restricted to layers III and V in the rat. Unlike the rat GABA-T + neurons were observed in layers II, III, and V of the gerbil cerebral cortex. These results suggest that the expression of GABA-T in the gerbil brain may be similar to that in the rat brain, except in the cerebral cortex.

4-Aminobutyrate Transaminase↗

PubMed2001

Molecular cloning and functional expression of bovine brain GABA transaminase.

We isolated a cDNA that encodes the bovine brain gamma-aminobutyrate transaminase (GABA-T; EC 2.6.1.19) from the lambda gt 11 cDNA library, which showed a high degree of sequence similarity to the corresponding enzymes from various sources. Northern blot analysis revealed two differentially expressed GABA-T transcripts of approximately 2.0 and 6.0 kb in the bovine tissues. Southern blot analysis indicates that the two GABA-T transcripts are encoded in a greater-than 10-kb, single-copy gene. Bovine GABA-T cDNA was expressed in E. coli using the pGEX bacterial- expression vector system. The overexpressed GABA-T was enzymatically active after purification, and it had very similar kinetic parameters when compared with those of other mammalian GABA-Ts.

4-Aminobutyrate Transaminase↗

PubMed2002

TTV infection and its relation to serum transaminases in apparently healthy blood donors and in patients with clotting disorders who have been investigated previously for hepatitis C virus and GBV-C/HGV infection in Belgium.

A novel DNA virus, TT virus (TTV), has been proposed as a possible etiologic agent for non A-E hepatitis. The aim of the present study was to determine the prevalence of TTV infection using PCR in healthy blood donors and in patients with clotting disorders who have been investigated previously for GBV-C/HGV and HCV infection in Belgium. In this study, PCR using primers proposed by Takahashi et al. [(1998) Hepatology Research 12:233-239] proved far more sensitive than those used by Okamoto et al. [(1998) Journal of Medical Virology 56:128-132]. The sequence of the PCR products showed 87% identity to the published sequence. TTV was present in 29.7% of healthy blood donors, a figure intermediate between the low rate of infection observed in Scotland and the high rates in the Far East. TTV was detected in 46.5% of 127 patients studied with clotting disorders as compared to 79.5% for HCV and 11.8% for GBV-C/HGV infection. However, there was no impact on the level of serum transaminases. Treatment with interferon for HCV infection co-infected with TTV suppressed temporarily serum TTV DNA. Therefore, it was concluded that TTV DNA is detected frequently in serum of healthy blood donors in Belgium and more often in patients with clotting disorders. TTV does not cause liver disease or contribute to the severity of liver disease.

Adolescent↗

PubMed1992

Transamination of some sulphur- or selenium-containing amino acids by bovine liver glutamine transaminase.

S-(3-aminopropyl)cysteine and Se-(3-aminopropyl)selenocysteine are deaminated by bovine liver glutamine transaminase. The corresponding alpha-keto acids, S-(3-aminopropyl)-thiopyruvic acid and Se-(3-aminopropyl)selenopyruvic acid, are produced which spontaneously cyclize to ketimine derivatives. They have been identified by comparing their UV absorption spectra and some chemical or chromatographic properties with chemically synthesized authentic samples. Also S-(2-aminoethyl)homocysteine is the substrate for the enzyme. Kinetic parameters determined in comparison to thialysine and selenalysine show that neither the presence of a sulphur or a selenium atom nor the relative position of the atom in the carbon chain appreciably affects the substrate specificity of the enzyme. However, the length of the carbon chain has some influence on it.

Amino Acids↗

PubMed1959

Anicteric virus hepatitis in a closed environment as shown by serum transaminase activity.

Although it has long been recognized that cases of virus hepatitis without jaundice outnumber those with jaundice, particularly among children, only recently-with the introduction of tests to determine the activity of serum transaminases-has it become possible to assess with any accuracy the real frequency of the anicteric forms. In the present paper, the authors report on an investigation in an institution for children in Rome. Some 1000 serum enzyme determinations were made on 104 children and 11 adults; detailed results are given. It was found that among the children anicteric hepatitis predominated over icteric hepatitis in a ratio of 30: 1 and that the total frequency of virus hepatitis of both forms was strikingly high. The clinical and epidemiological implications of these and associated findings are discussed.

Adult↗

PubMed1992

Glutamate pyruvate transaminase as an indicator of infection with Plasmodium falciparum.

A correlation is shown between the presence of trophozoites and/or gametocytes of Plasmodium falciparum in thick and/or thin blood films, with the enzyme glutamate pyruvate transaminase (GPT) and a marked increase in serum GPT as a probable consequence of the presence of malaria parasite inferred. It is suggested that serum GPT levels may be used as a reliable marker for malaria infection, but only complementary to microscopic detection of falciparum malaria, rather than being specifically diagnostic.

Alanine Transaminase↗