Fractal analysis of chromatin as a potential indicator of human exposures to ionizing radiation

Abstract

The theory of fractals, proposed by the mathematician Mandelbrot (1975), has been applied to many fields in Biology, mainly due to the property of self-similarity observed in the natural world, such as in the DNA molecule and chromatin structure. Many researches have proven the applicability of this mathematical analysis for the identification of cells containing mutations, in the case of cancers, or due to exposures to chemicals and ultraviolet radiation, but until the present moment, no work was done with ionizing radiation. The aim of the present study was to investigate the use of fractal analysis for the identification of irradiated cells, and to discuss its potential use as an indicator of human exposures to ionizing radiation. For this, 200 cells were digitalized, where 100 were from a blood sample irradiated with an absorbed dose of 3 Gy of gamma radiation, and 100cells were non-irradiated. Fractal dimensions (FD) were calculated by the method of Box-Counting. It was possible to notice an increase in FDs of chromatin after exposure to ionizing radiation, and an overdispersion of the values of FD only in irradiated sample. Also, when the data was reorganized in crescent order, it was possible to clearly distinct the irradiated sample from the non-irradiated one. With this, we present an efficient method for the identification of irradiated human blood samples, in a fast and most simplified way, what can be of valuable importance in cases where there is a need of quick responses to human exposures to ionizing radiation.

Análise fractal como ferramenta complementar no diagnóstico de carcinoma mucoepidermóide (CME) e carcinoma espinocelular oral (CEC)

“…A dimensão fractal é obtida pelo método de contagem por caixas, no qual, a partir do uso de quadrantes que cobrem a imagem, são contabilizados o número de caixas que cobrem pelo menos um pixel da imagem (N(r)), conforme descrito em Xavier et al (2018). Repete-se o procedimento com caixas de tamanhos diferentes, e então é traçado um gráfico duplo log de N(r) em função de r (lado das caixas).…”

Biophysics of the Radiation Cytogenetic Damage

“…Studies that investigate cells in interphase are still scarse, and are limited nowadays to only one technique, the premature chromosome condensation (PCC). More recently, the global architecture of the chromatin was analysed by fractal analysis (XAVIER et al, 2018). The idea of this research was based on the fractal globule model, by Lieberman-Aiden (2009).…”

“…FD will be the slope of the regression line, generated by the logarithm of the quantity of boxes in function to the logarithm of the size of the boxes. By the measurement of fractal dimension of the chromatin of irradiated lymphocytes, compared to non-irradiated lymphocytes, it as possible to distinguish between irradiated and non-irradiated sample (XAVIER et al, 2018). This may be an alternative method for screening irradiated victms in cases of mass casualties, where a high number of individuals has to be evaluated in a short period of time.…”