Poly(ADP-ribose)-synthesis and excision repair in light sensitive skin disorders.

Several data suggest a relationship of poly(ADP-ribose) (PAR) synthesis to DNA repair and the influence of some trace elements on the semiconservative and unscheduled DNA synthesis (UDS). Previously we found certain alterations in the UV-light induced UDS and in the contents of trace elements in the lymphocytes of patients with light sensitive skin disorders. In the recent study in polymorphic light eruption, cutaneous porphyrias and xeroderma pigmentosum the PAR synthesis and zinc, copper and manganese contents in the chromatin of the lymphocytes (measured by neutron activation analysis) were investigated.

In vitro study of paraquat effects on malondialdehyde formation in thymus cells.

The present experiments have shown that paraquat enhanced both O2- production and oxidation of exogenous NADPH in thymus cells by NADPH-dependent enzyme system. The effects of paraquat on malondialdehyde formation were also NADPH-dependent and opposite in the absence and in the presence of ferrous ions: Paraquat inhibited the NADPH-dependent malondialdehyde formation in the absence of Fe2+; it activated this formation in the presence of Fe2+ and had no effect on the nonenzymic Fe2+- and Fe2+-ascorbate-stimulated lipid peroxidation. It is suggested that the activating effect of paraquat on the enzymic NADPH-dependent MDA formation in the presence of Fe2+ is due to the formation of a powerful oxidant product (FeO2)+ or to some Fe2+-paraquat radical complex, acting similarly to the ADP-chelated ferrous ions.

Studies on the DNA-excision repair in lymphocytes of patients with recurrent Herpes simplex.

Investigations of the semiconservative DNA replication and the excision repair in lymphocytes of patients with recurrent herpes simplex showed defects that could lead to mutations in the DNA with following lower immuncompetence and possibility for activation of already present oncogenic virus formations within the cellular DNA.