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Modeling early physical and chemical events for DNA damage induced by photons and tritium beta particles

Abstract

A method has been developed to model production of single-strand breaks (SSB) and double-strand breaks (DSB) in Deoxyribo Nucleic Acid (DNA) by ionizing radiations. Modeling is carried out by Monte Carlo means and includes consideration of direct energy depositions in DNA molecules, production of chemical species following water radiolysis, diffusion of chemical species, and their interactions with each other and DNA. Computer-generated electron tracks in liquid water are used to model energy deposition and to derive the initial localization of chemical species. Atomistic representation of the DNA with a first hydration shell is used to derive direct energy depositions in DNA molecules and the resulting consequences, and to derive coordinates of reactive sites for modeling of the chemical stage of radiation damage. Diffusion of chemical species is followed in time, and the reactions of species with each other and DNA are considered to occur in an encounter-controlled manner. Time of diffusion follow-up is restricted to 10{sup -12}- 10{sup -9} s, which yields a diffusion length of hydroxyl radicals comparable to that in the cellular environment. DNA SSB are assumed to result from any direct energy depositions in the sugar/phosphate moiety, ionizations in water molecules bound to sugar/phosphate and hydroxyl attacks  More>>
Authors:
Moiseenko, V; [1]  Waker, A J; [2]  Prestwich, W V [1] 
  1. McMaster Univ., Dept. of Physics and Astronomy, Hamilton, Ontario (Canada)
  2. Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)
Publication Date:
Feb 01, 1998
Product Type:
Technical Report
Report Number:
AECL-11850; COG-97-374-I
Reference Number:
EDB-00:108617
Resource Relation:
Other Information: 145 refs., 12 tabs., 9 figs; PBD: Feb 1998
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRONMENTAL POLLUTANT EFFECTS ON LIVING ORGANISMS AND BIOLOGICAL MATERIALS; BIOLOGICAL RADIATION EFFECTS; CHROMOSOMAL ABERRATIONS; DNA; IONIZING RADIATIONS; PHOTONS; RADIATION INJURIES; RADIOLOGY; RBE; TRITIUM
OSTI ID:
20056641
Research Organizations:
Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)
Country of Origin:
Canada
Language:
English
Other Identifying Numbers:
TRN: CA0000195017420
Availability:
Available from INIS in electronic form
Submitting Site:
CANN
Size:
66 pages
Announcement Date:
Dec 18, 2000

Citation Formats

Moiseenko, V, Waker, A J, and Prestwich, W V. Modeling early physical and chemical events for DNA damage induced by photons and tritium beta particles. Canada: N. p., 1998. Web.
Moiseenko, V, Waker, A J, & Prestwich, W V. Modeling early physical and chemical events for DNA damage induced by photons and tritium beta particles. Canada.
Moiseenko, V, Waker, A J, and Prestwich, W V. 1998. "Modeling early physical and chemical events for DNA damage induced by photons and tritium beta particles." Canada.
@misc{etde_20056641,
title = {Modeling early physical and chemical events for DNA damage induced by photons and tritium beta particles}
author = {Moiseenko, V, Waker, A J, and Prestwich, W V}
abstractNote = {A method has been developed to model production of single-strand breaks (SSB) and double-strand breaks (DSB) in Deoxyribo Nucleic Acid (DNA) by ionizing radiations. Modeling is carried out by Monte Carlo means and includes consideration of direct energy depositions in DNA molecules, production of chemical species following water radiolysis, diffusion of chemical species, and their interactions with each other and DNA. Computer-generated electron tracks in liquid water are used to model energy deposition and to derive the initial localization of chemical species. Atomistic representation of the DNA with a first hydration shell is used to derive direct energy depositions in DNA molecules and the resulting consequences, and to derive coordinates of reactive sites for modeling of the chemical stage of radiation damage. Diffusion of chemical species is followed in time, and the reactions of species with each other and DNA are considered to occur in an encounter-controlled manner. Time of diffusion follow-up is restricted to 10{sup -12}- 10{sup -9} s, which yields a diffusion length of hydroxyl radicals comparable to that in the cellular environment. DNA SSB are assumed to result from any direct energy depositions in the sugar/phosphate moiety, ionizations in water molecules bound to sugar/phosphate and hydroxyl attacks on deoxyribose. DSB are assumed to result from two SSB on opposite strands separated by 10 or fewer base pairs. Photon radiations in the energy range 70 keV-1 MeV and tritium beta particles are considered. It is shown that for naked DNA in B-form (the configuration thought to be most biologically relevant) the effectiveness of tritium for SSB and DSB production is, within statistical uncertainties, comparable to photon radiation with energies in the range 70 keV-1 MeV, although a tendency for increased DSB production has been observed for 70 keV photons that represent orthovoltage X-rays and for tritium beta particles. It is predicted that hydroxyl radicals react with a much higher probability with bases (80% probability) than with sugar (20%). DNA breaks are virtually always combined with base damage, which contributes to break complexity. More than half of the DSB under the considered conditions (naked DNA, diffusion follow-up limited to 10{sup -9} s) are hydroxyl radical mediated. (author)}
place = {Canada}
year = {1998}
month = {Feb}
}