Modelagem estocástica aplicada ao Efeito Bystander Radioinduzido em culturas celulares e processos epidêmicos

Abstract

In this work we propose two Markovian stochastic models useful in the quantification of damage (e.g., cell death and mutations) in unirradiated cells which occupy the same environment e.g., culture medium or tissues containing directly irradiated cells with ionizing radiations like X rays and alpha particles. The fit of these models to experimental data yields the half-life of at least one factor among the ensemble of possible candidates to trigger these damages. These models furnish the variance of quantities such as cell survival and the cellular transformation frequency. We also study a markovian epidemic model with spatial structure. The principal new feature of this model is that the infection is transmitted by factors released from cells rather than via direct contact. This model is analyzed with two mean-field theory descriptions, one of which ignores correlations between the cellular state and the factorconcentration, and another that treats such correlations in an approximate manner. Monte Carlo simulations of the spread of infection on the square lattice yield values for the critical exponents and the fractal dimension consistent with the dynamic percolation universality class.