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CURATOR
A pinboard by
Thiwanka Weerakkody

Scientific Officer, Sri Lanka Atomic Energy Board

PINBOARD SUMMARY

The aim of this proposal is to assess background radiation in relation to both cytogenetic dosimetry

Summary
This study aims to assess background frequency of micronuclei formation and chromosomal aberrations in persons living in Ragama and Norochcholai using biodosimetry. Biodosimetry is a technique used to assess exposure to radiation which is superior to physical dosimetry. It gives a clearer picture of individual variation of susceptibility to radiation as well as the ability to perform biodosimetry for human risk assessment. This study is important to establish baseline levels of micronuclei formation and chromosomal aberrations especially as a nuclear power plant is to be commissioned in nearby India recently. Biodosimetry has been used to detect external and internal exposure to ionising radiations in scenarios of accidental and occupational exposure wherever nuclear power plants are present (IAEA, 2012). This study proposes to study samples of 92 subjects (in the age range of 20-60 years), comprising 46 from Norochcholai (area closest to the power plant) and 46 (matched for gender, age and life style) from Ragama (as a control). Background radiation levels in the atmosphere will be recorded by a Geiger counter with the assistance of the Atomic Energy Authority and trace elements in soil and water samples will be assessed using Gamma spectrometry and X- Ray Flouresence technique, respectively. Venous blood samples will be obtained and processed at the Biodosimetry laboratory at the Faculty of Medicine, University of Kelaniya. 1000 binucleate cells will be assessed and the mean spontaneous micronuclei formation will be estimated. 200 metaphases will be analyzed for chromosomal aberrations. The results of this study can be used as baseline data to monitor exposure to radiation in the selected population in the future.

4 ITEMS PINNED

The first in vivo multiparametric comparison of different radiation exposure biomarkers in human blood.

Abstract: The increasing risk of acute large-scale radiological/nuclear exposures of population underlines the necessity of developing new, rapid and high throughput biodosimetric tools for estimation of received dose and initial triage. We aimed to compare the induction and persistence of different radiation exposure biomarkers in human peripheral blood in vivo. Blood samples of patients with indicated radiotherapy (RT) undergoing partial body irradiation (PBI) were obtained soon before the first treatment and then after 24 h, 48 h, and 5 weeks; i.e. after 1, 2, and 25 fractionated RT procedures. We collected circulating peripheral blood from ten patients with tumor of endometrium (1.8 Gy per fraction) and eight patients with tumor of head and neck (2.0-2.121 Gy per fraction). Incidence of dicentrics and micronuclei was monitored as well as determination of apoptosis and the transcription level of selected radiation-responsive genes. Since mitochondrial DNA (mtDNA) has been reported to be a potential indicator of radiation damage in vitro, we also assessed mtDNA content and deletions by novel multiplex quantitative PCR. Cytogenetic data confirmed linear dose-dependent increase in dicentrics (p < 0.01) and micronuclei (p < 0.001) in peripheral blood mononuclear cells after PBI. Significant up-regulations of five previously identified transcriptional biomarkers of radiation exposure (PHPT1, CCNG1, CDKN1A, GADD45, and SESN1) were also found (p < 0.01). No statistical change in mtDNA deletion levels was detected; however, our data indicate that the total mtDNA content decreased with increasing number of RT fractions. Interestingly, the number of micronuclei appears to correlate with late radiation toxicity (r2 = 0.9025) in endometrial patients suggesting the possibility of predicting the severity of RT-related toxicity by monitoring this parameter. Overall, these data represent, to our best knowledge, the first study providing a multiparametric comparison of radiation biomarkers in human blood in vivo, which have potential for improving biological dosimetry.

Pub.: 24 Feb '18, Pinned: 11 Apr '18