T. Radivoyevitch et al., MISREJOINING OF DOUBLE-STRAND BREAKS AFTER X-IRRADIATION - RELATING MODERATE TO VERY HIGH-DOSES BY A MARKOV MODEL, Radiation research, 149(1), 1998, pp. 59-67
Citations number
26
Categorie Soggetti
Biology Miscellaneous","Radiology,Nuclear Medicine & Medical Imaging
Misrejoining of double-strand breaks (DSBs) detected with pulsed-field
gel electrophoresis (PFGE) after X irradiation of human cells at very
high doses (80-160 Gy) is related to dose-response relationships for
chromosome aberrations at moderate doses (1-5 Gy) by the Sax-Markov bi
nary eurejoining/misrejoining (SMBE) model. The SMBE model applies Sax
's breakage-and-reunion hypothesis to a subset of DSBs active in binar
y misrejoining and in binary eurejoining (accidental restitution). The
model is numerically consistent with both data on chromosome aberrati
ons and the data obtained by PFGE if proximity effects (restrictions o
n the range of interactions of DSB free ends) are present. Proximity e
ffects are modeled by partitioning the cell's nucleus into approximate
ly 400 interaction sites, with two active DSB free ends capable of rej
oining only if they were produced within the same site. Neglecting one
-track action, the SMBE model predicts a quadratic-linear dose-respons
e relationship for DSB misrejoining after exposure to low-LET radiatio
n; i.e., there is a quadratic response at moderate doses which becomes
linear as the dose becomes large, rather than vice versa. The linear
region results because at very high doses almost all of the active DSB
free ends misrejoin rather than eurejoin. (C) 1998 by Radiation Resea
rch Society.