[Carbonyl groups content on the basis of protein peroxidation analysis with total antioxidant status in blood of children with cancers].

Toxic oxygen free radicals have been implicated as important pathologic mediators in carcinogenesis. Several reports have found antioxidants and enzymes related to the antioxidants function at increased or decreased levels in blood of patients with cancers. In previous publications we observed that antioxidant barrier can be different in healthy children and children with cancers. This time we were looking for a stable marker of damaging effect of free radicals reactions in association with antioxidant barrier in blood. Carbonyl group level in proteins has been introduced as a good marker of oxidative stress damage. For this study we selected 60 children at the age of 3 to 16, who had been diagnosed as suffering from cancers: malignant (m) bone tumors (t) (n = 25), m. brain t. (n = 20), lymphoma malignum (n = 5), m. liver t. (n = 5) and m. germ cell t. (n = 5). The control group consisted of 40 age-matched healthy children (22 boys and 18 girls). We investigated the concentration of carbonyl groups (CG) in serum spectrofotometrically, according to the method of Levine. Plasma total antioxidant status (TAS) was estimated colorometrically with radical cation ABTS (2,2'-Azino di-[3-ethylbenzthiazoline sulphonatel]), erythrocyte glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities were assessed according to the method of Paglia & Valentine and Minami & Yoshikawa respectively (Kits of Randox Laboratories Ltd.). In this study the content of CG in plasma proteins has shown a significant increase (1.60 +/- 0.77 vs 0.78 +/- 0.15 nmol/mg protein, p < 0.001) and erythrocyte GSH-Px activity has shown a significant decrease (16.3 +/- 7.9 vs 25.1 +/- 15.8 U/gHb, p < 0.02) in children with malignant tumors. No differences were observed in SOD activity and TAS between sick and healthy children. A possible interpretation of this data suggests an inadequate antioxidants' protection in children with cancers. The relationship between the oxidative damage and carcinogenesis requires further investigations.