title: Increased dose-rate effect in V79-multicellular aggregates (spheroids). Relation to initial DNA lesions and repair.
abstract: Survival of exponentially growing V79 monolayer cells was measured after irradiation at low dose-rate (up to 1.1 Gy/h) and at high dose-rate (2.5 Gy/min) and compared to corresponding survival data of V79 spheroid cells. The so-called contact effect, the increased radioresistance of cells irradiated in spheroids, was expressed to a greater extent with low dose-rate exposure. Lesion fixation by hypertonic treatment was more pronounced in spheroid versus monolayer cells and abolished the contact effect. The reduced radiosensitivity of V79 spheroid cells could not be related to a reduced number of initial DNA lesions or a higher capacity to rejoin DNA breaks (measured by neutral elution). These findings suggest that the ratio of lesion repair to fixation/misrepair may differ between cells from spheroids and monolayer culture thus influencing the response of cells to dose-rate changes differentially.
authors.affiliation: Department of Clinical Radiology, University of Heidelberg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Frank
authors.forename: K J
authors.initials: KJ
authors.lastname: Weber
authors.forename: P
authors.initials: P
authors.lastname: Fritz
authors.forename: M
authors.initials: M
authors.lastname: Flentje
mesh_terms: D000818:Animals; D002449:Cell Aggregation; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D006224:Cricetinae; D003584:Cytological Techniques; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects*; D011829:Radiation Dosage; D011836:Radiation Tolerance; D012462:Saline Solution, Hypertonic / Q000494:pharmacology
chemical_list: D012462:Saline Solution, Hypertonic; D004247:DNA