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 comparison of the cost of laboratory-made reagents with that of commercial kits was made for three serum-enzyme estimations and three serum-hormone estimations. The cost of reagents in kit form could only be justified on economic grounds for serum aspartate transaminase, alanine transaminase, and lactic dehydrogenase if the laboratory performed less than about 35 tests per day. It is unlikely that the use of kits for serum tri-iodothyronine, thyroxine, and thyrotrophic hormone can be justified on economic grounds for any workload. It is estimated that between 2 million pounds and 3 million pounds is spent unnecessarily by the National Health Service each year to purchase commercially prepared reagents for the six tests studied.
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PMID:Comparison of cost of preparing reagents in laboratory with cost of using commercial kits. 7 63

The overall performances of several enzyme reagent kits for alkaline phosphatase, creatine kinase, lactic dehydrogenase, and aspartate aminotransferase were evaluated using an ABA-100 Bichromatic Analyzer. Interassay precision using this instrument with commercial reagents compared well with published data for similar analyses performed at university hospitals and referral laboratories. Significantly poorer precision with lower limits of linearity was observed when reagents recommended for use at 30 C were used at 37 C. Significant differences in measured levels of creatine kinase, lactic dehydrogenase, and aspartate aminotransferase due to different lots of expendable cuvettes were found for elevated levels of these enzymes. All kit reagents met manufacturers' claims for stability; however, different absolute levels of lactic dehydrogenase were observed with one kit reagent on successive days. Slight hemolysis affected creatine kinase levels measured with some reagent kits significantly more than others.
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PMID:Evaluation of commercial enzyme reagent kits by use of a semiautomated chemistry analyzer. 47 90

The expert group "Drug Interference in Clinical Chemistry" of the Bureau of Reference, Directorate General for Research, Science and Education of the Commission of the European Communities, consisting of one participant of each member of the European Communities, presents this first report on the final results of its activities. Within the framework of a first stage basic program, the paper describes interferences of therapeutic and elevated doses of ascorbic acid on commonly used clinical chemical methods. This is the result of a bipartite study that was jointly planned, carried out and evaluated. Local and personal influences have been eliminated, as have variations due to methodology, measurement equipment and reagents, in order to be able to present distinct causal effects of ascorbic acid. No definite influence of ascorbic acid on analytical values for urea, cholesterol, calcium, protein, bilirubin, aspartate aminotransferase and alkaline phosphatase could be detected. At therapeutic concentrations, ascorbic acid distinctly interferes with the analysis of glucose, uric acid, creatinine and inorganic phosphate. The extent and direction of interferences vary, depending on the type of reaction, kit and apparatus. In some cases the influence of ascorbic acid results in severe disturbance of the analytical methods leading to useless values.
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PMID:Drug interference in clinical chemistry: studies on ascorbic acid. 62 9

Sources of variation in assays of aspartate aminotransferase (EC 2.6.1.1) activity were examined in an interlaboratory survey and through an examination of materials used as calibration materials in these assays. Four highly stable lyophilized specimens containing human cytoplasmic enzyme, with activities of 0, 22, 46, and 96 U/liter at 30 degrees C and optimal substrate concentrations, were assayed by 319 laboratories. Mean values obtained on these specimens by laboratories using 2,4-dinitrophenylhydrazine kits varied among manufacturers and deviated from values expected from this procedure. The average coefficient of variation (CV) with these kits was greater than 20%. Automated continuous-flow procedures with use of diazonium salt showed the best precision (av CV, less than 10%). However, the automated continuous-flow malate dehydrogenase/NADH coupled method produced an average CV greater than 20%. Results from each of the automated methods were related to a reference malate dehydrogenase/NADH coupled continuous kinetic assay method by temperature relationships alone. Mean values from manual diazonium salt procedures were 1.7-fold greater than similar reference values (av CV was 18%). The higher results were attributed to the use of poorly-defined units and to an artifact caused by chromophore stabilizers in this procedure when aqueous samples are used. The average CV in continuous kinetic methods varied among kit manufacturers, ranging from 6 to 28% for the specimen of highest activity. Variations in results were much larger at 366 nm than at 340 nm than at 340ity. Variations in results were much larger at 366 nm than at 340 nm. Interassay relationships of these methods are presented. Concentrations of pyruvate in commercially available calibration materials differed between manufacturers, varied in stability, and deviated from the expected concentration. For some colorimetric assays the precision attained on reported absorbance values for the enzyme specimens was of the same order of magnitude as that for pyruvate standards. Other sources of error are revealed by the interlaboratory survey. The value of commercially available sources of enzyme activity as calibration or control materials was assessed by evaluating the following properties: activity at suboptimal concentrations of L-aspartate or 2-oxoglutarate, temperature effects, preincubation lability owing to aspartate and phosphate, pyridoxal phosphate saturation, contamination with glutamate dehydrogenase, and manufacturer's rated activity. These properties are compared to those of human cytoplasmic enzyme in a human serum matrix.
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PMID:Interlaboratory proficiency, intermethod comparison, and calibrator suitability in assay of serum aspartate aminotransferase activity. 113 21

Forty-three kits for clinical chemical analysis of GOT (aspartate aminotransferase) were evaluated. The reference method was the kinetic method performed on the Abott ABA-100 Bichromatic Analyzer. Specific data are tabulated for each kit and include ease and speed of testing and performance data. Most kits failed to provide completely adequate labelling information. Reproducibility CV for the kits varied widely (4.20 to 21.26 for the normal pool and 1.57 to 20.51 for the high pool). Many kits gave significant numbers of false positive and false negative results on patient samples. There is a need for manufacturers to either derive their own normal ranges or to establish exact equivalency values with the method used to establish the normal values. No difference was demonstrated between performance by two skilled technologists. However, we did detect lot-to-lot variation and differences in performance between narrow bandpass and wide bandpass spectrophotometers.
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PMID:Performance of "kits" used for clinical chemical analysis of GOT (aspartate aminotransferase). 126 Oct 5

Two hundred and forty-three patients receiving renal replacement therapy (RRT) and 20 renal unit staff were tested for antibodies to hepatitis C (HCV). Three patients (1.2%) were positive by the first generation test kit, the lowest rate in patients receiving RRT reported in the literature to date. These three, and eight other patients tested positive by the second generation kit, a prevalence rate of 4.5%. Anti-HCV antibody positivity was associated with higher mean serum alanine aminotransferase (p = 0.0003) and aspartate aminotransferase (p = 0.018) levels. However, only one of the 11 anti-HCV positive patients had liver transaminase levels more than twice the upper limit of the laboratory reference range. Anti-HCV positivity was associated with a higher mean number of units of blood transfused (p = 0.035). None of 20 staff were anti-HCV positive. Twenty-five of 212 (11.7%) patients reported a history of liver disease; none of these were anti-HCV positive. Hepatitis B surface antigen was detected in eight of 215 (3.7%) patients, of which three were e antigen positive. There was evidence of past hepatitis B infection in 53 of 215 (24.7%) patients, more frequently in Maoris (p = 0.001). Overall, significantly raised liver transaminases were present in three of 198 (1.5%) patients and in no staff. This unit has a remarkably low prevalence of antibodies to HCV, an observation supported by the low rate of abnormal serum liver enzymes.
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PMID:Prevalence of antibodies to hepatitis C virus in patients receiving renal replacement therapy, and in the staff caring for them. 128 95

Serum chemistry values were obtained from 64 adult San Joaquin kit foxes (Vulpes macrotis mutica) in western Kern County, California (USA). The goal of the study was to establish normal chemistry values for this endangered species. No significant differences were found for mean values of alanine aminotransferase (217.1 IU/l), alkaline phosphatase (44.2 IU/l), cholesterol (145.6 mg/dl), total protein (5.8 g/dl), creatinine (0.63 mg/dl), calcium (8.2 mg/dl), albumin (3.0 g/dl), glucose (129.2 mg/dl), amylase (196.8 IU/l), sodium (153.7 mEq/l) and phosphorus (5.42 mg/dl) between sexes or seasons. Significant differences were noted for aspartate aminotransferase, blood urea nitrogen and potassium between seasons. Possible disturbances in normal hepatic and renal functions were noted.
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PMID:Serum chemistry values of the endangered San Joaquin kit fox (Vulpes macrotis mutica). 151 73

Serum human hepatocyte growth factor levels were measured using a newly developed enzyme-linked immunosorbent assay kit in patients with liver diseases. Serum human hepatocyte growth factor levels were increased in correlation with derangements of prothrombin time, total bilirubin and other parameters reflecting hepatocellular dysfunction in 112 patients with chronic liver disease. The levels were positively correlated with serum AST and ALT levels in 59 of these patients whose prothrombin times were within the normal range. Abnormally increased serum human hepatocyte growth factor levels were found in 100% of the determinations in 16 patients with fulminant hepatic failure and in 80% of the determinations in 16 patients with chronic hepatic failure. The levels greater than 1 ng/ml, however, were found in 94% of determinations in the former group, but only in 16% of the determinations in the latter group. This difference was seen irrespective of prothrombin time or hepatic coma grades. In patients with fulminant hepatic failure serum human hepatocyte growth factor levels were increased immediately after plasma exchange using heparin as the anticoagulant in 71% of the determinations. This increase disappeared 12 hr after discontinuation of plasma exchange. In 17 of 39 patients with chronic renal failure who had no liver disease, serum human hepatocyte growth factor levels were abnormally increased before hemodialysis using heparin, and the levels were elevated immediately after hemodialysis in all the patients. The increase of serum human hepatocyte growth factor levels in hepatic failure may be the result of hepatocellular dysfunction and necrosis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Significance of serum human hepatocyte growth factor levels in patients with hepatic failure. 153 Jul 86

In 154 blood samples from adult and pediatric liver transplant recipients with variable degrees of hepatic and renal dysfunction, the specific monoclonal antibody-based Sandimmune RIA kit gave CsA results that were highly correlated with HPLC values. In contrast, assay of CsA levels with the PARIA in 213 samples showed values that varied between 1.8 and 18.8 times those determined by HPLC. In adults, the extent of this variation in the CsA HPLC/PARIA ratio was highly correlated with values of BIL and to a lesser extent with serum ALP; additionally, in children, correlations with AST and GGT were noted.
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PMID:Blood cyclosporine concentrations in liver transplant recipients: assay method and influence of changed hepatic and renal function. 329 Dec 74

Kits of five different suppliers, composed according to the Dutch recommendations for determination of the enzyme activity of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, gamma-glutamyltransferase, alkaline phosphatase, and creatine kinase, were intercompared. Activity concentrations of the enzymes in human sera were measured under defined conditions, evaluated, and related to the actual composition of the kits. Concentrations of all kit components were determined by various analytical techniques. The overall results of the activity measurements and the composition of at least three kits inter-agree well. We found deviations as great as 10% in our analytical evaluation of the kits of the other two suppliers, which can partly be accounted for.
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PMID:Kits for enzyme determinations compared: relation between composition and quality. 614 61


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