RESUMO
Organoselenium compounds belonging to the class of monoselenides, such as selenomethionine (SeM) and methylselenocysteine (MSeCys) and diselenides including selenocystine (SeCys) and selenopropionic acid (SePA), were examined for their comparative radioprotective effects using in vitro models. Effects of these compounds on the inhibition of gamma-radiation induced lipid peroxidation in liposomes, protein carbonylation in bovine serum albumin (BSA) and strand breaks in pBR322 plasmid DNA, assessed, respectively, by the formation of thiobarbituric acid reactive substances, formation of 2,2'-dinitrophenyl hydrazine (DNPH) carbonyl complex and horizontal gel electrophoresis, were used to compare their radioprotective ability. The IC 50 values for SeCys, SePA, SeM and MSeCys for lipid peroxidation were 27 +/- 1, 33 +/- 2, 200 +/- 8 and 163 +/- 4 microM, respectively, and the values for inhibition of protein carbonylation were >200, 300 +/- 6, 464 +/- 8 and 436 +/- 3 microM, respectively. Inhibition of DNA strand break formation was tested at 200 microM for all the compounds and SePA and SeCys exhibited a protective effect on DNA, while SeM and MSeCys did not lead to any protection. The in vitro cytotoxicity studies in normal and tumor cells revealed that MSeCys and SeM were not cytotoxic to lymphocytes and EL4 tumor cells at the concentrations employed. In contrast, SeCys was toxic, with a higher effect on tumor cells than lymphocytes. Our studies suggest that the non-toxic diselenides like SePA should be explored as protective agents against gamma-irradiation induced damage.
Assuntos
Compostos Organosselênicos/farmacologia , Protetores contra Radiação/farmacologia , Animais , Bovinos , Linhagem Celular Tumoral , Cisteína/administração & dosagem , Cisteína/análogos & derivados , Cisteína/química , Cisteína/farmacologia , Cistina/administração & dosagem , Cistina/análogos & derivados , Cistina/química , Cistina/farmacologia , DNA/química , DNA/efeitos dos fármacos , DNA/efeitos da radiação , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , Raios gama/efeitos adversos , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos da radiação , Lipossomos/química , Lipossomos/efeitos da radiação , Linfócitos/efeitos dos fármacos , Linfócitos/efeitos da radiação , Linfoma/tratamento farmacológico , Linfoma/radioterapia , Camundongos , Camundongos Endogâmicos C57BL , Compostos Organosselênicos/administração & dosagem , Compostos Organosselênicos/química , Carbonilação Proteica/efeitos dos fármacos , Carbonilação Proteica/efeitos da radiação , Protetores contra Radiação/administração & dosagem , Protetores contra Radiação/química , Selenocisteína/análogos & derivados , Selenometionina/administração & dosagem , Selenometionina/química , Selenometionina/farmacologia , Soroalbumina Bovina/efeitos dos fármacos , Soroalbumina Bovina/efeitos da radiação , Substâncias Reativas com Ácido Tiobarbitúrico/química , Neoplasias do Timo/tratamento farmacológico , Neoplasias do Timo/radioterapiaRESUMO
We report a 30-year-old man with superior vena cava syndrome due to fibrosis from a previously irradiated malignant thymoma. The patient presented 4 years after the initial treatment, after having been lost to follow-up. Investigations revealed total obstruction of the superior vena cava, and right subclavian and right internal jugular vein. The patient underwent an extra-anatomic bypass (ringed polytetrafluoroethylene graft 10-mm diameter) between the left internal jugular vein and the left femoral vein brought in a subcutaneous tunnel over the anterior chest and abdominal wall. Entry to the thoracic cavity was avoided due to extensive fibrotic changes visualized in the computed tomographic chest scan. Follow-up Doppler at 2 months, 6 months, 1 year, and 3 years showed a patent graft. An internal jugular vein to the femoral vein bypass is a simple method for palliation of superior vena cava syndrome.