Comparative studies of induction and repair of DNA double-strand breaks in X-irradiated alveolar macrophages and resting peripheral blood lymphocytes using constant-field gel electrophoresis.
Induction and repair of X-ray-induced DNA double-strand breaks (dsbs) was compared for normal broncho-alveolar macrophages and human peripheral blood lymphocytes, using CHO cells as a reference cell model. The cells, upon their separation, were processed in a similar manner. After X-irradiation, cell lysis and proteinase K treatment, the DNA samples were subjected to constant-field gel electrophoresis (CFGE) followed by fluorimetric densitometry for quantification of released DNA. Induction of dsbs after X-ray doses of 5-100 Gy was found to show no gross differences for all cell systems used. Repair of dsbs was studied after X-ray dose of 60 Gy for up to 24 h after irradiation. The repair curves obtained proved to be similar for bronchoalveolar macrophages and CHO cells (97% of all dsbs rejoined after 24 h). However, in blood lymphocytes from normal subjects and from bone marrow recipients, dsb repair proceeded rapidly only for 0.5-1 h post-irradiation, being followed by the gradual degradation of DNA at longer intervals. The kinetics of DNA degradation correlated with cytological features of pyknosis and necrosis.
Chukhlovin
A
A
N.N. Petrov Research Institute of Oncology, Russian Ministry of Public Health, Saint-Petersburg.
Dahm-Daphi
J
J
Gercken
G
G
Zander
A R
AR
Dikomey
E
E
D000818:Animals; D016466:CHO Cells; D002417:Cattle; D006224:Cricetinae; D004249:DNA Damage / Q000528:radiation effects*; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000528:radiation effects*; D016676:Macrophages, Alveolar / Q000528:radiation effects*; D014965:X-Rays