PARENT SESSION
1:30 PM to 3:30 PM
Wednesday, April 24, 2002
Poster Session 32 Dose Fractionation, Dose Rate Effects
Room: Nevada Exhibition Center
(P37-361) Media from AL cells exposed to 
rays (<6 Gy) does not alter survival but abolishes the decreased mutant induction normally seen with fractionated doses.
Ueno, Akiko*,1, Vannais, Diane1, Waldren, Charles1, 1 Dep of Radiological Health Sciences, Ft. Collins, CO
ABSTRACT-
We found earlier that dose fractionation can reduce the yield of CD59- mutants in AL human-hamster cells. We here examined if media from irradiated AL cells affects fractionated dose recovery of killing & mutation. Conditioned media were prepared in three ways: (A) 4 days on confluent, unirradiated cells; (B) As (A) but cells & medium given 2 Gy/day for 4 days; (C) As A, but one 6 Gy dose. These cells were discarded; the medium reused as below. Virgin AL cells in media A,B or C were given: (1) no irradiation; (2) one 3 Gy dose; (3) a fractionated dose of 4 x 0.75 Gy. These cells were trypsinized and replated to quantify survival & incidence of CD59- mutants. We found: (i) survival at 3 Gy & the increase in survival with fractionation were the same in all media; but (ii) media from irradiated plates (B,C)abolished the fractionated dose reduction. Involvement of long-lived radicals (described by Watanabe & colleagues) is being investigated. Supported by: NIH/NCI; NASA/NSCORT.
KEYWORDS: mutation, conditioned media, gamma rays