MARCIA AUGUSTA DA SILVA
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Artigo IPEN-doc 07134 Evaluation of the effect of 90Sr β-radiation on human blood cells by chromosome aberration and single cell gel electrophoresis (comet assay) analysis2001 - OLIVEIRA, E.M.; SUZUKI, M.F.; NASCIMENTO, P.A.; SILVA, M.A.; OKAZAKI, K.Among various environmental genotoxins, ionizing radiation has received special attention because of its mutagenic, carcinogenic and teratogenic potential. In this context and considering the scarcity of literature data, the objective of the present study was to evaluate the effect of 90Sr β-radiation on human cells. Blood cells from five healthy donors were irradiated in vitro with doses of 0.2-5.0 Gy from a 90Sr source (0.2 Gy/min) and processed for chromosome aberration analysis and for comet assay. The cytogenetic results showed that the most frequently found aberration types were acentric fragments, double minutes and dicentrics. The α and β coefficients of the linear-quadratic model, that best fitted the data obtained, showed that 90Sr β-radiation was less efficient in inducing chromosome aberrations than other types of low linear energy transfer (LET) radiation such as 3H β-particles, 60Co γ-rays, 137Cs and 192Ir and X-rays. Apparently, 90Sr β-radiation in the dose range investigated had no effect on the modal chromosome number of irradiated cells or on cell cycle kinetics. Concerning the comet assay, there was an increase in DNA migration as a function of radiation dose as evaluated by an image analysis system (tail moment) or by visual classification (DNA damage). The dose-response relation adequately fitted the non-linear regression model. In contrast to the cytogenetic data, 90Sr β-radiation induced more DNA damage than 60Co γ-radiation when the material was analyzed immediately after exposures. A possible influence of selective death of cells damaged by radiation was suggested.Artigo IPEN-doc 08666 Induction of micronuclei by 153Sm-EDTMP in peripheral blood lymphocytes in vitro2002 - SUZUKI, M.F.; SILVA, M.A.; GUIMARAES, M.I.C.C.; OKAZAKI, K.The purpose of this study was to evaluate the degree of cytological radiation damage to lymphocytes induced by beta particle (71% E max = 810 keV) and gamma rays (29% E max = 103 keV) of 153Sm (T½ = 46.3 h). Samarium-153 ethylene diamine tetramethylene phosphonate (153Sm-EDTMP) has been successfully applied as a radiopharmaceutical for palliation of metastatic bone pain at dose of 37 MBq/kg (1mCi/kg) intravenously. Blood samples from four healthy donors and three patients with no previous radiotherapy were exposed to 370, 555 (equivalent to the activity administrated in vivo) and 1110 kBq/mL during one hour in vitro. Then the lymphocytes were cultured for cytokinesis block micronucleus assay that has received increased attention for biological monitoring of radiation exposure. The MN induction in binucleated cells (BNC) at 370 and 555 kBq/mL was not significantly increased and showed no difference between the groups. This result may be explained as a consequence of the sensibility of this technique. The radiation damage to peripheral blood lymphocytes (PBL) exposed to 1110 kBq/mL may be considered to be equivalent to that observed after an external irradiation with 60Co at doses of 0.38 Gy in healthy donors (MN/BNC = 0.053 ± 0.041) and 0.51 Gy in patients (MN/BNC = 0.069 ± 0.040). This study showed that the use of 153 Sm-EDTMP induced no significant increase in the micronucleation of PBL at radioactive concentration lower than 555 kBq/mL (37MBq/kg) and also that the radiosensitivity of the patients was higher at 1110 kBq/mL than that of the healthy donors.