The determination of thiobarbituric acid reactants (TBARs) is a widely used method for investigating overall lipid peroxidation. An assay kit that could be used with plasma and lipid fractions would facilitate standardization of the method. The results reported here indicate that the malondialdehyde (MDA) kit manufactured by Sobioda (Grenoble, France) complies with criteria of good analytical practices. The detection limit was 0.11 mumol of MDA per liter of plasma. The within-run (CV = 1.8-3.3%) and between-run (CV = 3.3-4.4%) precisions were acceptable. The analytical recovery of MDA after supplementing human plasma samples with tetraethoxypropane standards varied from 88% to 100%. The mean (SD) lipoperoxide concentration determined in 32 healthy adults, ages 20-40 years, was 2.51 (0.25) mumol/L. No significant sex-related difference was noted: 2.57 (0.28) in men vs 2.44 (0.20) mumol/L in women. Applying the method to lipid fractions showed that lipoprotein fractions contain relatively little MDA: 0.07 (0.03) mumol/L of plasma for very-low-density lipoproteins and 0.19 (0.10) mumol/L for low-density lipoproteins.

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MATERIALS AND METHODSSkin fibroblasts were cultivated in Ham F10 medium supplemented with 15 % fetal calf serum, antibioticantimycotic solution, in 5% carbon dioxide at 37°C. Cells were harvested by trypsin, rinsed three times, suspended in deionized water and lysed by freezing and thawing in an acetone dry-ice bath. Lysates were centrifuged at 2000 g and supernatants were collected for further investigation. Protein concentration was determined by the method of Lowry and copper and zinc by flameless atomic absorption.