Biomedical subjects
Publications and source records attributed to F Naghizadeh.
2-Hydroxybutyrate is enzymically oxidized by the LDH of human serum. Optimal concentrations of hydrogen ion, substrate and coenzyme for this oxidation by sera from patients with disease of the heart or liver have been determined at 37 degrees C. The linearity of this reaction is limited to a point at which an assay procedure employing a 2-hydroxyburyrate substrate seems unsuitable.
The reduction of pyruvate, 2-oxobutyrate, hydroxy-pyruvate and glyoxylate under optimal conditions at 37 degrees by extracts of human heart, kidney, pancreas, skeletal muscle and liver has been examined. The ratios of reduction rates, particularly of glyoxylate and 2-oxobutyrate reveal a capacity to differentiate the isoenzyme composition of the tissue extracts.
1. The lactate dehydrogenase activity of 89 sera from patients suffering myocardial infarction and of 55 sera from patients with hepatocellular damage was assayed under optimal conditions using pyruvate, alpha-oxobutyrate, hydroxypyruvate and glyoxylate as substrates. Activity was also measured with lactate as substrate at different pH values. 2. The ratios of activities under these different assay conditions were calculated for both series of patients. Correct differentiations for single ratios ranged from virtually nil for hydroxypyruvate/alpha-oxobutyrate to is greater than 93 per cent for glyoxylate/hydroxypyruvate and glyoxylate/alpha-oxobutyrate. This was little improved by the use of multiple ratios involving up to seven separate assays. 3. The activity ratio of hydroxypyruvate to pyruvate which is consistently greater than unity was found to be inverted in a case of morphine poisoning.
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