title: Effects of irradiated medium with or without cells on bystander cell responses.
abstract: Recent studies have indicated that extranuclear or extracellular targets are important in mediating the bystander genotoxic effects of alpha-particles. In the present study, human-hamster hybrid (A(L)) cells were plated on either one or both sides of double-mylar dishes 2-4 days before irradiation, depending on the density requirement of experiments. One side (with or without cells) was irradiated with alpha-particles (from 0.1 to 100 Gy) using the track segment mode of a 4 MeV Van de Graaff accelerator. After irradiation, cells were kept in the dishes for either 1 or 48 h. The non-irradiated cells were then collected and assayed for both survival and mutation. When one side with cells was irradiated by alpha-particles (1, 10 and 100 Gy), the surviving fraction among the non-irradiated cells was significantly lower than that of control after 48 h co-culture. However, such a change was not detected after 1h co-culture or when medium alone was irradiated. Furthermore, co-cultivation with irradiated cells had no significant effect on the spontaneous mutagenic yield of non-irradiated cells collected from the other half of the double-mylar dishes. These results suggested that irradiated cells released certain cytotoxic factor(s) into the culture medium that killed the non-irradiated cells. However, such factor(s) had little effect on mutation induction. Our results suggest that different bystander end points may involve different mechanisms with different cell types.
authors.affiliation: Center for Radiological Research, Vanderbilt Clinic 11-201, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, USA. hz63@columbia.edu
authors.forename: Hongning
authors.initials: H
authors.lastname: Zhou
authors.forename: Masao
authors.initials: M
authors.lastname: Suzuki
authors.forename: Charles R
authors.initials: CR
authors.lastname: Geard
authors.forename: Tom K
authors.initials: TK
authors.lastname: Hei
mesh_terms: D000818:Animals; D024201:Bystander Effect / Q000528:radiation effects*; D016466:CHO Cells; D002450:Cell Communication / Q000528:radiation effects; D002460:Cell Line / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D003470:Culture Media / Q000528:radiation effects*; D006801:Humans; D006822:Hybrid Cells / Q000528:radiation effects*; D009154:Mutation / Q000528:radiation effects; D011829:Radiation Dosage
chemical_list: D003470:Culture Media