title: Detrimental and protective bystander effects: a model approach.
abstract: This work integrates two important cellular responses to low doses, detrimental bystander effects and apoptosis-mediated protective bystander effects, into a multistage model for chromosome aberrations and in vitro neoplastic transformation: the State-Vector Model. The new models were tested on representative data sets that show supralinear or U-shaped dose responses. The original model without the new low-dose features was also tested for consistency with LNT-shaped dose responses. Reductions of in vitro neoplastic transformation frequencies below the spontaneous level have been reported after exposure of cells to low doses of low-LET radiation. In the current study, this protective effect is explained with bystander-induced apoptosis. An important data set that shows a low-dose detrimental bystander effect for chromosome aberrations was successfully fitted by additional terms within the cell initiation stage. It was found that this approach is equivalent to bystander-induced clonal expansion of initiated cells. This study is an important step toward a comprehensive model that contains all essential biological mechanisms that can influence dose-response curves at low doses.
authors.affiliation: Department of Materials Engineering and Physics and Biophysics, University of Salzburg, Salzburg, Austria. helmut.schoellnberger@sbg.ac.at
authors.forename: H
authors.initials: H
authors.lastname: Schöllnberger
authors.forename: R E J
authors.initials: RE
authors.lastname: Mitchel
authors.forename: J L
authors.initials: JL
authors.lastname: Redpath
authors.forename: D J
authors.initials: DJ
authors.lastname: Crawford-Brown
authors.forename: W
authors.initials: W
authors.lastname: Hofmann
mesh_terms: D024201:Bystander Effect / Q000502:physiology* / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects*; D002471:Cell Transformation, Neoplastic / Q000528:radiation effects*; D003198:Computer Simulation; D019610:Cytoprotection / Q000502:physiology* / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D008954:Models, Biological; D011829:Radiation Dosage