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:2.6.1.1 (aspartate aminotransferase)
21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A sensitive and specific sandwich enzyme immunoassay (EIA) for human cytosolic aspartate aminotransferase (c-AST) has been developed. Serum was incubated with anti-c-AST antibody-coated polystyrene beads, and further incubated with anti-c-AST antibody-peroxidase conjugate. The peroxidase activity bound to the polystyrene bead was proportional to the amount of c-AST. The method allows measurement of serum c-AST ranging from 50-2,000 micrograms/l. No cross-reactivity with m-AST or other serum components was observed. Recovery, within-day precision, and day-to-day precision were good. The levels of c-AST obtained by the proposed EIA were compared with those based on enzyme activity. The results suggest that there is a considerable excess of immunologically active but catalytically inactive c-AST in normal and patient's sera, and that variable specific activities of c-AST are may be found in sera from different individuals.
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PMID:Enzyme immunoassay of human cytosolic aspartate aminotransferase. 639 41

The rabbit antiserum and mouse monoclonal hybridoma antibody against porcine cytosolic aspartate aminotransferase (c-AAT) (or cytosolic glutamic oxaloacetic transaminase (c-GOT)) were produced and compared for the localization of c-AAT in rat liver. An indirect immunocytochemical technique was performed using peroxidase-conjugated goat immunoglobulin (Ig) G anti-rabbit IgG and peroxidase-conjugated rabbit IgG anti-mouse IgG as the second antibody. Rats were perfused with paraformaldehyde-lysine-periodate fixative and the liver fragments were immersed in 4% paraformaldehyde and transferred to 10% dimethyl sulfoxide overnight and subjected to cryostat sectioning. The rabbit IgG antibody, 3 individual monoclonal antibodies, and a mixture of these 3 monoclonal antibodies were applied to the tissue sections, respectively, using the same concentration. Under the same experimental conditions, the c-AAT was localized in each individual hepatocyte by both monoclonal and polyclonal antibodies. However, a mixture of three monoclonal antibodies gave stronger staining than a single monoclonal antibody; although two antibodies yield more intense staining than just one, it was still less intense than for three. The conventional rabbit polyclonal antibody against c-AAT produced more reaction product than the combined three monoclonal antibodies. It is concluded that for immunocytochemical study, the use of a single monoclonal antibody is sensitive enough to localize its tissue antigen under the present experimental condition. To obtain a stronger reaction product, a combination of several monoclonal antibodies, at least three or more, may give better staining.
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PMID:A comparative study of polyclonal and monoclonal antibodies for immunocytochemical localization of cytosolic aspartate aminotransferase in rat liver. 685 5

There is substantial evidence supporting the role of aspartate or glutamate as the neurotransmitter of the auditory nerve. The concentration of aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1), an enzyme associated with the metabolism of these amino acids, is high in axons and terminals of the auditory nerve. Antibodies were raised against aspartate aminotransferase and used in immunocytochemical studies to determine its localization in the cochlear nucleus of the guinea pig. Indirect immunofluorescence techniques were used for light microscopic localization of aspartate aminotransferase-like immunoreactivity in normal guinea pigs and guinea pigs with auditory nerve lesions. Fluorescent rings of aspartate aminotransferase-like immunoreactivity were seen around spherical cells in the anteroventral cochlear nucleus. In animals with auditory nerve lesions, rings were no longer seen in the ipsilateral cochlear nucleus. Immunoreactivity was also seen on cells in the posteroventral cochlear nucleus and in auditory nerve fibers. Ultrastructural studies were done in the rostral anteroventral cochlear nucleus, using the peroxidase-antiperoxidase technique. Aspartate aminotransferase-like immunoreactivity was seen at axosomatic synapses on large spherical cells in terminals with the morphological characteristics of auditory nerve terminals. Other classes of terminals on the soma of large spherical cells showed no immunoreactivity. It was concluded that aspartate aminotransferase-like immunoreactivity is present in axons and terminals of the auditory nerve. These findings indicate that aspartate aminotransferase-like immunoreactivity may serve as a marker at terminals where aspartate or glutamate is a neurotransmitter.
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PMID:Immunocytochemical localization of aspartate aminotransferase immunoreactivity in cochlear nucleus of the guinea pig. 694 43

A biochemical system was devised to identify aneuploids of Nicotiana tabacum. Leaf tissue from 6 nullihaploids, 4 nullisomics, and 10 monosomics was analyzed electrophoretically on slab acrylamide gels. The staining systems used were for peroxidase, esterase, superoxide dismutase, malate dehydrogenase, and glutamate oxaloacetate transaminase. Nullihaploids and nullisomics could be distinguished from each other and from haploid or disomic types by their unique isozyme banding patterns. The banding patterns of the monosomics closely resembled those of the disomic. Morphologically similar aneuploids from different populations had similar isozyme banding patterns.
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PMID:Identification of aneuploids in Nicotiana tabacum by isozyme banding patterns. 711 87

1. Glutatione peroxidase activity (EC 1.11.1.9) and erythrocyte stability were measured in Friesian bull calves which were given for 36 weeks semi-purified diets either adequate or low in selenium or vitamin E or both. 2. Dietary Se or vitamin E content had no effect on growth rate and haematlogical values. None of the calves exhibited clinical deficiency symptoms and serum aspartate amino transferase (EC 2.6.1.1) and creatine phosphokinase (EC 2.7.3.2) activities remained normal. Heart and skeletal muscles of all calves appeared macroscopically and microscopically normal ato autopsy. 3. Glutathione peroxidase activity in plasma, blood and other tissues, except the testis, was significantly lower in calves receiving low dietary Se but was independent of dietary vitamin E content. 4. Plasma vitamin E levels decreased rapidly and to very low levels in calves given low vitamin E diets irrespective of the Se content of the diet. 5. A low dietary vitamin E intake increased the susceptibility of erythrocytes to auto- and peroxidative haemolysis whereas a low Se intake in the presence of adequate vitamin E did not. However, erythrocytes from calves receiving low Se and low vitamin E were more susceptible to peroxidative haemolysis than erythrocytes from calves receiving low vitamin E and adequate Se. The effect of dietary vitamin E content on osmotic haemolysis induced by hypotonic saline was variable. 6. The results suggest that measurement of blood glutathione peroxidase activity and the susceptibility of erythrocytes to auto- or peroxidative haemolysis could be used for the differential diagnosis of subclinical Se and vitamin E deficiency in ruminants.
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PMID:Glutathione peroxidase activity and erythrocyte stability in calves differing in selenium and vitamin E status. 728

We investigated whether bile salts (BS) with different hydrophobic-hydrophilic properties interact with ethanol on bile secretion, enzyme (aspartate transaminase [AST], lactate dehydrogenase [LDH]) release in the perfusate, liver ultrastructure, and vesicular exocytosis in the isolated perfused rat liver. Ethanol (0.1 or 1%) promoted a rapid decrease of bile flow and BS secretion in livers perfused with taurocholate (TCA), the physiologic BS in the rat (-28% decrease of baseline values with 0.1% and -34% with 1% ethanol). The inhibitory effect of ethanol on bile flow and BS secretion was significantly (P < .02) attenuated by perfusing liver with the hydrophilic BS, tauroursodeoxycholate (TUDCA), and it was exacerbated (P < .02) by perfusion with the hydrophobic BS, taurodeoxycholate (TDCA). The release of AST and LDH in the perfusate was unaffected by 0.1% ethanol, but increased threefold to fivefold by 1% ethanol in TCA-perfused livers. This cytolitic effect of ethanol was not observed in TUDCA-perfused livers, but it was enhanced (P < .03) by perfusion with TDCA. No ultrastructural abnormalities were found in either TCA- or TUDCA-perfused livers, with or without 1% ethanol. Only minimal changes were found in livers perfused with TDCA alone, but, in the presence of TDCA, 1% ethanol induces marked mitochondrial damage. The biliary excretion of the fluid phase marker horseradish peroxidase was inhibited by ethanol, an effect reversed by TUDCA (P < .02) and exacerbated by TDCA (P < .04). In conclusion, this study demonstrates that hydrophilic BS such as TUDCA counteract the inhibitory effect of ethanol on bile secretion and vesicular exocytosis as well as the ethanol-induced cytolitic effect in the isolated perfused rat liver. In the presence of hydrophobic BS such as TDCA, the exposure to ethanol promotes a marked inhibition of bile secretion and vesicular exocytosis as well as prominent mitochondrial damage.
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PMID:Functional and ultrastructural features of ethanol/bile salts interaction in the isolated perfused rat liver. 770 87

This study was designed to examine the role of Kupffer cells in polymorphonuclear neutrophils (PMN) activation and infiltration after severe total hepatic ischemia. Male rats pretreated with either normal saline (NS group; n = 58) or gadolinium chloride (7 mg/kg; GC group, n = 57) for 2 days were subjected to 90 min total hepatic ischemia. In addition to 7-day survival rate, aspartate aminotransferase (AST), PMN liver infiltration, plasma myeloperoxidase (MPO), and interleukin-1 (IL-1) levels were serially measured from the end of ischemia to 360 min after reperfusion. Survival rate of the GC group significantly improved to 67% (P < 0.01), whereas that of the NS group remained at 20%. Extremely high AST levels (5,372 +/- 231 IU/liter) were obtained in the NS group, which correlated with the degree of hepatic necrosis. Very high IL-1 (270.3 +/- 91.2 pg/ml) and MPO (1.7 +/- 0.4 U/ml) levels were also seen in the NS group. The GC group significantly inhibited increases in AST, IL-1, and MPO levels as well as PMN infiltration in the liver compared to the NS group (P < 0.05). Our study demonstrated that Kupffer cell activation has an important role in the development of reperfusion injury after total hepatic ischemia through IL-1 release, and PMN activation and infiltration.
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PMID:Role of Kupffer cells in neutrophil activation and infiltration following total hepatic ischemia and reperfusion. 805 66

The purposes of this study were to clarify the role of neutrophilic proteases in the pathogenesis of hepatic ischemia/reperfusion injury and to determine whether urinary trypsin inhibitor (UTI) pretreatment attenuated liver ischemia/reperfusion injury in rats. Livers from male Sprague-Dawley rats were subjected to 90 min of no-flow warm ischemia followed by 120 min of reperfusion. Rats were divided into a UTI group and a control group. In the control group, 120-min reperfusion of the liver produced a significant increase in myeloperoxidase activity, a significant decrease in ATP and energy charge, and a marked increase in the serum aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase levels. In the UTI group, the myeloperoxidase activity was significantly attenuated (P < 0.01), ATP and energy charge were significantly improved (P < 0.01 and P < 0.05, respectively), and the elevation in serum aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase was also markedly suppressed (P < 0.05, P < 0.01, and P < 0.05, respectively) compared with the control group. Sections through the livers of control rats showed severe hepatocyte necrosis with neutrophil infiltration. In the UTI group, there was slight congestion and hepatocyte necrosis. The survival rate after 90-min liver ischemia was significantly improved compared with that in the control group (P < 0.05). The results of this study suggest that pretreatment with UTI significantly attenuates liver reperfusion injury, perhaps by inhibiting neutrophil proteases.
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PMID:Effect of protease inhibitor on ischemia/reperfusion injury of the rat liver. 827 98

We developed an efficient enzyme-linked immunosorbent assay (ELISA) system for measurement of human liver-type arginase in serum. A conjugate of the Fab' fragment of anti-human liver (recombinant) arginase IgG and horseradish peroxidase was used as the second antibody. This assay is highly specific, sensitive, and reproducible, enabling us to detect arginase at concentrations as low as several micrograms per liter without any prior processing of serum. The reaction is linear up to 200 micrograms/L. The arginase concentration in serum, as determined by this method, increased markedly and temporarily at the time of surgical operation or later injury to the liver. The increase was accompanied or followed by increases in serum concentrations of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, suggesting that the arginase emerged from damaged hepatocytes. In view of a limited tissue distribution of liver-type arginase, our ELISA system may be useful in diagnosis of various hepatic disorders as well as follow-up of postoperative conditions of patients.
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PMID:Enzyme immunoassay of liver-type arginase and its potential clinical application. 838 7

We investigated whether anticoagulation would diminish ischemia-reperfusion injury of the liver. Liver ischemia was induced in rats by occluding the portal vein for 30 min. Anticoagulant was injected intravenously 10 min before occlusion. Serum concentrations of cytokine-induced neutrophil chemoattractant (CINC) in untreated rats increased following reperfusion, reaching a peak at 6 hr, then decreasing gradually to control levels by 24 hr. CINC levels in rats pretreated with heparin (50 units/kg), AT-III (250 units/kg), or DEGR-Xa (10 mg/kg) peaked at 3 hr after reperfusion and declined to baseline within 12 hr; peak CINC values were significantly lower than in untreated control rats. Expression of CINC mRNA in liver tissue paralleled the CINC serum levels. Both myeloperoxidase activity and the number of neutrophils in the liver were decreased in the anticoagulant groups. In addition, significant correlations were observed between the maximum values of AST, ALT, and LDH versus the peak CINC levels following ischemia-reperfusion. These results indicate that the release of CINC after ischemia-reperfusion of the liver is mediated by activation of coagulation within the hepatic microcirculation.
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PMID:Anticoagulant pretreatment attenuates production of cytokine-induced neutrophil chemoattractant following ischemia-reperfusion of rat liver. 868 28


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