Repair of gamma-irradiation-induced DNA single-strand breaks in human bone marrow cells: effects of a second irradiation.
Human bone marrow mononuclear cells were isolated by density gradient centrifugation and irradiated with a 137Cs source. The extent of irradiation-induced single-strand breaks (SSBs) and alkali labile sites as well as their repair was investigated by using the alkaline single-cell gel electrophoresis (SCGE) technique, or comet assay. A dose-dependent increase in the length of DNA migration was seen when cells were exposed to 0, 2.43 and 5.43 Gy of gamma-irradiation. Complete repair of DNA SSBs was observed over 24 h after a dose of 2.43 Gy. Second challenges of 0, 2.43 and 5.43 Gy resulted in similar SSBs as with the first irradiation. Furthermore, the DNA repair kinetics of two cell populations, one previously unirradiated and the other having received 2.43 Gy 24 h earlier, was indistinguishable. This means that most human bone marrow cells retain their genetic stability after a dose of 2.43 Gy if SSBs are used as an endpoint.
Lankinen
M H
MH
Department of Clinical Chemistry, Tampere University Hospital, Finland.
Vilpo
J A
JA
D001853:Bone Marrow / Q000528:radiation effects*; D001854:Bone Marrow Cells; D002478:Cells, Cultured / Q000528:radiation effects; D002499:Centrifugation, Density Gradient; D002588:Cesium Radioisotopes / Q000009:adverse effects / Q000494:pharmacology; D053938:DNA Fragmentation / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004586:Electrophoresis; D006801:Humans; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000528:radiation effects; D008856:Microscopy, Fluorescence
D002588:Cesium Radioisotopes