TYROSINE METABOLISM, ANTIOXIDANT STATUS AND SOME PARAMETERS OF FREE-RADICAL LIPID PEROXIDATION IN CHILDREN SUFFERING FROM MELANOMA AND PIGMENTED NEVI
Blood plasma content of tyrosine and malonic dialdehyde (MDA), the product of lipid peroxidation was measured in children with pigmented nevi and melanoma as well as in healthy children. Antioxidant status was estimated by measuring the glutathione level as well as the activity of catalase, superoxide dismutase (SOD), glutathione peroxidase (GP), and glutathione reductase (GR) in erythrocytes. Excretion of tyrosine and its metabolites was also analysed. Significant deficiency of antioxidant status was found out in children with melanoma and pigmented nevi. Pigmented nevi seem to predetermine the pathological deviations of tyrosine metabolism towards oxidative pathway of tyrosine breakdown. At the same time, the usual correlations between the parameters of tyrosine metabolism, antioxidant status and free-radical lipid peroxidation turned out to be damaged in this group of children. The results obtained suggest that the children with pigmented nevi are therefore to be considered as the group at high oncological risk. Following the above-stated parameters could be useful in long-term monitoring of children with marginal nevi.
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