Unit:
Κατεύθυνση Ιατρική Φυσική-ΑκτινοφυσικήLibrary of the School of Health Sciences
Author:
Gkikoudi Angeliki
Supervisors info:
Γεωργία Τερζούδη, Ερευνήτρια Α', ΙΠΡΕΤΕΑ, ΕΚΕΦΕ "Δημόκριτος"
Μαρία Παραβατού, Ερευνήτρια Α', ΙΠΡΕΤΕΑ, ΕΚΕΦΕ "Δημόκριτος"
Πηνελόπη Μπουζιώτη, Ερευνήτρια Α', ΙΠΡΕΤΕΑ, ΕΚΕΦΕ "Δημόκριτος"
Original Title:
Μελέτη της επίδρασης γ-ακτινοβολίας χαμηλών δόσεων με μεθόδους κυτταρογενετικής και μοριακής γενετικής
Translated title:
Study of low dose gamma-radiation effect with cytogenetic and molecular methos
Summary:
Our daily lives are full of exposures in many sources of ionizing and non-ionizing radiation. The interaction of ionizing radiation with biological materials has tremendous results in individuals’ health. That is the main reason that led the scientific community to investigate the exact results that come from the exposure in ionizing radiation. The main goals over the decades was to find the correlation between the exposure and the increase of chromosomal abnormalities, genomic instability and aneuploidy, as they contribute to the mechanism of carcinogenesis after exposure to radiation, to establish the main principles of radiation protection and to take in advantage the results of the interaction of ionizing radiation with biological materials for therapeutic purposes.
In recent years, the use of ionizing radiation for diagnostic purposes has been increased and that results to the expansion of the ionizing radiation effects research in the low dose scale. Annually, a large portion of people getting exposed to low doses of ionizing radiation as they undergo diagnos-tic testing that involves ionizing radiation but the biological effects of the low dose exposures has not been fully elucidated.
The present study was structured in this direction, as the topic is the investigation of the low dose ionizig radiation effect in biological materials with cytogenetics and molecular genetics methods such as the Micronucleus (MN) method, the phosphorylated histone γ-Η2ΑΧ method (γ-H2AX foci) and the fluorescence in situ hybridization (FISH) method. More specifically, the study was divided in three sections and in each section one of the three methods is included. Peripheral blood sam-ples were obtained from 5 healthy donors, and irradiated with low doses of radiation.
The first series of experiments involves the application of the micronucleus method for all 5 in vitro exposured samples with 0,05 and 1 Gy. The results of the analysis showed that the micronu-cleus method does not detect a statistically significant increase in chromosomal lesions for a low radiation dose (50 mGy). Also, the results of the analysis showed that there is a large variation in the number micronucleus in both control and low irradiated samples.
The second series of experiments includes the most sensitive method for the detection of the low dose ionizing radiation results, the method of phosphorylated histone γ-Η2ΑΧ . This method was used for the analysis of samples that obtained from all 5 healthy donors after their in vitro expo-sure to low radiation dose of 0.05 Gy. The results of the analysis showed that there was a statisti-cally significant increase in gamma-induced γ-H2AX foci compared to non-irradiated samples (control) right after the exposure and 24 hours post exposure with a total decrease of the counted γ-H2AX foci due to repair after 24 hours. An important result regarding the repair of DSBs is the large variation of repair among donors as the analysis of the samples 24 hours after radiation showed.
The last series of experiments focused on the study of induced chromosomal instability after expo-sure to low doses of radiation by the method of detecting asymmetric cell divisions. For this pur-pose, a combination of the Micronucleus method and the fluorescence in situ hybridization meth-od (i-CBMN) was applied for the first 3 healthy donors after irradiation of the samples with 0.05 and 2 Gy doses, for two different time points after exposure (72 and 96 hours after irradiation). According to preliminary results that obtained from the third series of experiments, there is not a statistically significant dose-dependent increase in asymmetric cell divisions after exposure to low radiation dose for any of the three time points.
In conclusion, in order to have a better overview of the effects of low radiation doses and the con-sequent risk for both patients and radiation workers, further research in the direction of associa-tion the induction and repair of γ-H2AX foci with biological effects at the cellular level is needed.
Furthermore, the analysis of asymmetric cell divisions after several cell cycles and their correla-tion with chromosomal instability and aneuploidy can contribute effectively in the understanding of the mechanisms of radiation carcinogenesis.
Main subject category:
Health Sciences
Keywords:
Gamma radiation, Low doses, Ionizing radiation, Cytogenetics methods, Radiation effects
