Double-strand break (DSB) misrejoinings, observed
with pulsed-field gel electrophoresis (PFGE)
after x-irradiation of human cells at very
high doses (80--160 Gy),
are related to chromosome aberration dose-response relations at
moderate doses (1--5 Gy) by the
Sax-Markov binary eurejoining/misrejoining (SMBE) model. The SMBE model
applies Sax's breakage-and-reunion scenario to a subset of DSBs
active in binary misrejoining and in binary eurejoining
(accidental restitution).
The model is numerically consistent with both chromosome
aberration data and the PFGE data
if proximity effects (restrictions on the range
of DSB free end interactions) are present.
Proximity effects are modeled by
partitioning the cell's nucleus into approximately 400
interaction sites, with two active DSB free ends capable of rejoining
only if they were produced within the same
site. Neglecting one-track action, the SMBE model
predicts a quadratic-linear (QL) low LET dose-response relation for
DSB misrejoining, 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.
Radiation Research, 149, 59-67, 1998.
Tomas Radivoyevitch*, David G. Hoel*,
Allen M. Chen+
and Rainer K. Sachs+.
*Department of Biometry and Epidemiology,
Medical University of South Carolina,
Charleston, SC 29425;
+Department of Mathematics,
University of California, Berkeley, CA 94720.
Corresponding author: Tomas Radivoyevitch, Department of Biometry and
Epidemiology,
Medical University of South Carolina,
Charleston, SC 29425 USA;
tel: 803-766-7064; fax: 803-792-0539; e-mail: radivot@musc.edu.
Hi-dose