title: A novel automated assay for malate dehydrogenase isoenzymes.
abstract: We have developed a new automated method for the determination of malate dehydrogenase (MDH) isoenzymes in serum employing guanidine hydrochloride. Our proposed method showed good reproducibility; within-run precision coefficient of variations (CVs) were less than 2.5 (mean 13.6-42.9 U/L) for total MDH (T-MDH) and less than 6.7% (mean 6.3-23.5 U/L) for mitochondrial MDH (m-MDH) (n = 10). The upper detection limit of the proposed method exhibited good linearity up to 1,000 U/L for both T-MDH and m-MDH. In the proposed m-MDH reagent, the presence of up to 2,000 U/L of cytosolic MDH(c-MDH) activity had no effect on the outcome of m-MDH assay. Results of our proposed method (y) correlated well with those of the electrophoretic method (x) giving the regression equation: y = 1.46 x + 6.87 (N = 30); r = 0.99. Normal concentrations of various anticoagulants and bilirubin did not affect the assay results. Both ascorbic acid and glucose exhibited a slight positive interference with the proposed assay. Clinically, we found that m-MDH activity in serum had greater diagnostic predictive value than T-MDH activity for judging successful outcome of reperfusion therapy; the prognosis was poor when the m-MDH/T-MDH ratio was greater than 20%.
authors.affiliation: Department of Laboratory Medicine, Kumamoto University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sugiuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Uji
authors.forename: Y
authors.initials: Y
authors.lastname: Shirahase
authors.forename: H
authors.initials: H
authors.lastname: Okabe
mesh_terms: D000328:Adult; D003067:Coenzymes / Q000032:analysis / Q000097:blood; D004586:Electrophoresis; D005260:Female; D019791:Guanidine; D006146:Guanidines; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000032:analysis* / Q000097:blood; D007770:L-Lactate Dehydrogenase / Q000097:blood / Q000378:metabolism; D016014:Linear Models; D008291:Malate Dehydrogenase / Q000032:analysis* / Q000097:blood; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000201:enzymology; D010072:Oxamic Acid / Q000494:pharmacology; D011379:Prognosis; D011489:Protein Denaturation; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D003067:Coenzymes; D006146:Guanidines; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; D019791:Guanidine; D010072:Oxamic Acid