RESUMO
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. UV induced PAR synthesis was generally lower in the cells of polymorphic light eruption and especially in xeroderma pigmentosum with a reduced repair capacity whereas in cutaneous porphyrias no difference was observed. Some correlations occurred between the contents of trace elements studied and UDS as well in each group tested. It seems that PAR investigations throw new light upon our understanding of the pathomechanism of photodermatoses.
Assuntos
Reparo do DNA , Transtornos de Fotossensibilidade/metabolismo , Poli Adenosina Difosfato Ribose/biossíntese , Dano ao DNA , Humanos , Linfócitos/metabolismo , Porfirias/metabolismo , Dermatopatias/metabolismo , Raios Ultravioleta , Xeroderma Pigmentoso/metabolismoRESUMO
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.
Assuntos
Malonatos/biossíntese , Malondialdeído/biossíntese , Paraquat/farmacologia , Timo/efeitos dos fármacos , Adrenocromo/metabolismo , Animais , Compostos Ferrosos/farmacologia , Masculino , NADP/metabolismo , Oxirredução , Ratos , Ratos Endogâmicos , Superóxidos/metabolismo , Timo/metabolismoRESUMO
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.
Assuntos
Reparo do DNA , Herpes Simples/sangue , Linfócitos/metabolismo , Adolescente , Adulto , Idoso , Criança , Reparo do DNA/efeitos da radiação , Replicação do DNA/efeitos da radiação , Feminino , Humanos , Linfócitos/efeitos da radiação , Masculino , Pessoa de Meia-Idade , Mutação , Recidiva , Raios UltravioletaRESUMO
The effect of radiation induced single-strand breaks in nuclear DNA and the repair of this damages on the sedimentation properties of nucleoids obtained from rat spleen, rat thymus and rat Yoshida tumour cells was studied. A dose dependent effect of ethidium bromide intercalation on the behaviour of supercoiled DNA could be demonstrated. The repair process of radiation induced single-strand breaks in the DNA of Yoshida tumour cells was delayed in the presence of prostaglandin E2 in the incubation medium. Additionally some in vivo repair experiments were carried out on cells of whole body irradiated rats.
