Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.1 (aspartate aminotransferase)
 21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Legumes obtain a substantial portion of their nitrogen (N) from symbiotic N2 fixation in root nodules. The glutamine synthetase (GS, EC 6.3.1.2)/glutamate synthase (GOGAT) cycle is responsible for the initial N assimilation. This report describes the analysis of a transgenic alfalfa (Medicago sativa L.) line containing an antisense NADH-GOGAT (EC 1.4.1.14) under the control of the nodule-enhanced aspartate amino-transferase (AAT-2) promoter. In one transgenic line, NADH-GOGAT enzyme activity was reduced to approximately 50%, with a corresponding reduction in protein and mRNA. The transcript abundance for cytosolic GS, ferredoxin-dependent GOGAT (EC 1.4.7.1), AAT-2 (EC 2.6.1.1), asparagine synthase (EC 6.3.5.4), and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) were unaffected, as were enzyme activities for AAT, PEPC and GS. Antisense NADH-GOGAT plants grown under symbiotic conditions were moderately chlorotic and reduced in growth and N content, even though symbiotic N2 fixation was not significantly reduced. The addition of nitrate relieved the chlorosis and restored growth and N content. Surprisingly, the antisense NADH-GOGAT plants were male sterile resulting from inviable pollen. A reduction in NADH-GOGAT enzyme activity and transcript abundance in the antisense plants was measured during the early stages of flower development. Inheritance of the transgene was stable and resulted in progeny with a range of NADH-GOGAT activity. These data indicate that NADH-GOGAT plays a critical role in the assimilation of symbiotically fixed N and during pollen development.
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PMID:Decreased NADH glutamate synthase activity in nodules and flowers of alfalfa (Medicago sativa L.) transformed with an antisense glutamate synthase transgene. 1093 93

Abamectin is widely used as an insecticide and an anthelmintic. A previous report indicated that abamectin was used to commit suicide and led to death in Taiwan. This investigation focused on the toxicological effects of abamectin on serum aspartate aminotransferase (AST) and nitrate/nitrite (NO) levels in rats. After rats were gavaged with abamectin ranging from 1 to 20 mg/kg/body weight, AST and NO levels were examined within 12 h. AST and NO levels were elevated in abamectin-dosed rats in a dose-dependent manner. The least increase of AST corresponded to the highest enhancement of NO release at 6 h. A negative correlation coefficient (r=-0.55) between AST and NO was found. Both NG-nitro-L-arginine-methyl ester and aminoguanidine, inhibitors of nitric oxide synthase, increased the AST level induced by abamectin. These findings suggest that NO may be involved in the alteration of AST release induced by abamectin in rats.
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PMID:Abamectin effects on aspartate aminotransferase and nitric oxide in rats. 1152 77

The effects of betaine or taurine on hepatotoxicity induced by lipopolysaccharide (LPS) were examined in adult male SD rats. Rats were provided with drinking water containing either 1% betaine or taurine for 2 weeks prior to challenge with LPS (5 mg/kg, iv). Supplementation with betaine or taurine protected the animals from induction of LPS hepatotoxicity as measured by changes in aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities and total bilirubin levels in serum, and hepatic glutathione contents. LPS challenge increased serum TNF-alpha and nitrate/nitrite in rats, which were reduced by betaine or taurine intake. Taurine depletion induced by supply of drinking water containing 3% beta-alanine for 7 days did not enhance the LPS-induced hepatic damage or the decrease in hepatic glutathione level. The results indicate that intake of betaine or taurine attenuates the LPS-induced hepatotoxicity resulting from activation of Kupffer cells.
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PMID:Attenuation of bacterial lipopolysaccharide-induced hepatotoxicity by betaine or taurine in rats. 1189 13

In a recent study in rats, alanine aminotransferase (ALT), the preferred plasma biomarker of hepatocellular injury in rats, was ineffective at detecting marked hepatic necrosis produced by acetaminophen (Human and Experimental Toxicology 19, 277-83, 2000). In contrast, glutamate dehydrogenase (GLDH) was markedly elevated. Accordingly, these enzymes were comprehensively evaluated as plasma biomarkers of hepatocellular injury in rats using several other models of hepatic injury, including partial hepatectomy and exposure to methapyrilene, dexamethasone, cyproterone, isoniazid, lead nitrate, and Wyeth-14643. Other enzymes also evaluated were aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), and the hepatobiliary marker alkaline phosphatase (ALP). Compared to plasma ALT increases, plasma GLDH increases were up to 10-fold greater, up to 3-fold more persistent, and occurred at times following hepatocellular injury when plasma ALT was not increased. Plasma GLDH activity was not inhibited by the test compounds, whereas ALT was substantially inhibited by both isoniazid and lead nitrate. While plasma GLDH activity was unaffected by induction, ALT was induced by cyproterone and dexamethasone, and ALP was induced by Wyeth-14643 and partial hepatectomy. GLDH was concluded to be a more effective biomarker of acute hepatic injury than ALT, AST, SDH or ALP in the rat, based primarily on the large increase following hepatocellular injury, prolonged persistence in the blood following injury, high sensitivity for detection of injury (including pre-necrotic injury), high tissue specificity, and lower susceptibility to inhibition or induction.
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PMID:Advantages of glutamate dehydrogenase as a blood biomarker of acute hepatic injury in rats. 1214 42

The efficacy of Tiron (4,5-dihydroxybenzene 1,3-disulfonic acid disodium salt) was examined in the treatment of beryllium-induced maternal and developmental toxicity in rats. Single administration of beryllium nitrate at a dose of 50 mg/kg (i.m.) on day 13 of gestation caused reductions in fetal and placental weights, the number of implantation sites and number of corpora lutea, as well as causing post-implantation loss, stunted growth, increase in the number of resorptions, and also a disturbed sex ratio. Maternal toxicity was demonstrated by reduction in body weight gain. Administration of beryllium also showed significant alteration in the hematological and biochemical indices of the mother as well as the fetus. Marked decreases were recorded in hemoglobin percentage, blood sugar levels, serum protein contents and serum alkaline phosphatase activity. By contrast, significant elevation was found in the activity of transaminases (aspartate aminotransferase and alanine aminotransferase). Tissue protein contents, glycogen contents, activities of alkaline phosphatase, adenosine triphosphatase and succinic dehydrogenase of kidney, lungs and uterus, and maternal and fetal liver all showed significantly decreased values after beryllium exposure, and remarkable elevation was observed in acid phosphatase, glucose-6-phosphatase and hepatic lipid peroxidation. These parameters were restored considerably with administration of 471 mg/kg i.m. Tiron from days 14 to 18 of gestation. Atomic absorption spectrophotometry also revealed a high concentration of beryllium in different organs of pregnant rats. Interestingly, a small amount of metal ion was also detected in the fetus and reduced accumulation of beryllium was noticed after Tiron treatment.
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PMID:Protective effect of Tiron (4,5-dihydroxybenzene-1,3-disulfonic acid disodium salt) against beryllium-induced maternal and fetal toxicity in rats. 1218 11

An important biochemical feature of autotrophs, land plants and algae, is their incorporation of inorganic nitrogen, nitrate and ammonium, into the carbon skeleton. Nitrate and ammonium are converted into glutamine and glutamate to produce organic nitrogen compounds, for example proteins and nucleic acids. Ammonium is not only a preferred nitrogen source but also a key metabolite, situated at the junction between carbon metabolism and nitrogen assimilation, because nitrogen compounds can choose an alternative pathway according to the stages of their growth and environmental conditions. The enzymes involved in the reactions are nitrate reductase (EC 1.6.6.1-2), nitrite reductase (EC 1.7.7.1), glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 1.4.1.13-14, 1.4.7.1), glutamate dehydrogenase (EC 1.4.1.2-4), aspartate aminotransferase (EC 2.6.1.1), asparagine synthase (EC 6.3.5.4), and phosphoenolpyruvate carboxylase (EC 4.1.1.31). Many of these enzymes exist in multiple forms in different subcellular compartments within different organs and tissues, and play sometimes overlapping and sometimes distinctive roles. Here, we summarize the biochemical characteristics and the physiological roles of these enzymes. We also analyse the molecular evolution of glutamine synthetase, glutamate synthase and glutamate dehydrogenase, and discuss the evolutionary relationships of these three enzymes.
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PMID:Nitrogen-assimilating enzymes in land plants and algae: phylogenic and physiological perspectives. 1220 56

Using a rat model of septic shock we studied the effects of Evodia rutaecarpa, a Chinese herbal medicine with antimicrobial and anti-inflammatory activity, on haemodynamic parameters, biochemical markers of organ function and nitric oxide (NO) production. Anaesthetized rats challenged with a high dosage of endotoxin (Escherichia coli lipopolysaccharide; LPS; 50 mg kg(-1), i.v.) for 6 h showed a severe decrease in mean arterial pressure. This was accompanied by delayed bradycardia, vascular hyporeactivity to phenylephrine and increase in plasma levels of lactate dehydrogenase, aspartate aminotransferase, bilirubin and creatinine, as well as NOx (NO2- plus NO3-). Pretreatment with ethanol extract of E. rutaecarpa (25, 50 and 100 mg kg(-1), i.v.), 1 h before LPS, dose-dependently prevented the circulation failure, vascular hyporeactivity to phenylephrine, prevented liver dysfunction and reduced the NOx over-production in plasma in endotoxaemic rats. A selective inducible NO-synthase (iNOS) inhibitor, aminoguanidine (15 mg kg(-1), i.v.), also effectively ameliorated the above pathophysiological phenomenon associated with endotoxaemia so that the normal condition was approached. Endotoxaemia for 6 h resulted in a significant increase in iNOS activity in the liver homogenate, which was attenuated significantly by E. rutaecarpa pretreatment. In summary, E. rutaecarpa, at the dosages used, exerted these beneficial effects probably through inhibition of iNOS activity and subsequent modulation of the release of NO. These significant results may offer E. rutaecarpa as a candidate for the treatment of this model of endotoxaemia.
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PMID:Evodia rutaecarpa protects against circulation failure and organ dysfunction in endotoxaemic rats through modulating nitric oxide release. 1239 3

The efficacy of two chelating agents (Tiron and calcium disodium EDTA) in the treatment of beryllium induced blood biochemistry and hepatic histopathological alteration was investigated at different duration in female albino rats. Single administration of beryllium nitrate at a dose of 50 mg/kg (im) showed significant decrease in haemoglobin percentage, blood sugar level, protein contents and activity of alkaline phosphatase. On the contrary significant elevation was found in the activity of transaminases (AST and ALT). Tiron was found to be more effective than CaNa2EDTA in reducing the beryllium induced haematological alterations and histopathological lesions in liver. These findings were further confirmed by AAS thus, in which reduced beryllium body burden was seen in liver and blood with Tiron.
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PMID:Comparative effectiveness of Tiron (4,5-dihydroxy benzene 1,3-disulphonic acid disodium salt) and CaNa2EDTA with time after beryllium poisoning. 1255 11

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were grown for 68 days in a growth chamber in nutrient solutions with ammonium, nitrate or ammonium nitrate as the nitrogen source. Among the nitrogen sources tested, whole-seedling biomass, relative growth rate (RGR), root and shoot elongation, and number of lateral roots, were greatest in seedlings grown with ammonium. In the absence of nitrogen, plant growth and formation of lateral roots were poor. Initially, glutamine synthetase, NAD-glutamate dehydrogenase and aspartate aminotransferase activities were high in young roots and shoots, but all three enzymatic activities decreased after one month of culture. In root apices, glutamine synthetase and aspartate aminotransferase activities were higher than NAD-glutamate dehydrogenase activity. Enzymatic activities were often higher in ammonium-fed seedlings than in seedings supplied with the other forms of nitrogen. Activities of all three enzymes were significantly reduced in seedlings grown in the absence of nitrogen. The beneficial effect of ammonium is discussed on the basis of its involvement in the assimilation pathways of Douglas-fir.
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PMID:Effects of nitrogen source on growth and activity of nitrogen-assimilating enzymes in Douglas-fir seedlings. 1265 84

Biochemical changes, total proteins, glycogen, aspartate and alanine (AAT and ALAT) amino transferases were studied with exposure of sublethal concentrations of NH3-N, NO2-N and NO3-N to the freshwater fish Catla catla (Hamilton), Labeo rohita (Hamilton) and Cirrhinus mrigala (Hamilton). Depletion in the food reserves and enzyme activity was observed in all the three fish species exposed to these toxicants. Hence, the concentrations of NH3, NO2 and NO3 in water need to be monitored in water quality in aquaculture practices.
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PMID:Studies of some biochemical changes in the tissues of Catla catla (Hamilton), Labeo rohita (Hamilton) and Cirrhinus mrigala (Hamilton) exposed to NH3-N, NO2-N and NO3-N. 1267 77


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