Abstract
Purpose In vivo effects of intermittent irradiation are influenced by recovery from sublethal damage (SLDR) and reoxygenation, so contribution of the two factors were investigated using murine tumors. Methods and materials 1-cm-diameter SCCVII tumors growing in the legs of C3H/HeN mice were used. First, effects of 5 fractions of 6 Gy given at intervals of 2.5–15 min were compared using an in vivo– in vitro assay, by clamping the tumor-bearing legs to exclude the influence of reoxygenation. In the second and third experiments, changes in the hypoxic fraction at 0–15 min after 13 or 5 Gy were assessed by a paired cell survival method. Fourth, effects of 5 fractions of 5 Gy given at intervals of 3–10 min under conditions of limited reoxygenation were compared using a growth delay assay. Results Cell survival from clamped tumors tended to increase with elongation of the intervals, but not significantly. The hypoxic fraction tended to decrease at 5–15 min from the level immediately after irradiation. Effects on tumor growth tended to decrease with elongation of the intervals. Conclusions Reoxygenation occurring within 5–15 min appeared to compensate for SLDR in SCCVII tumors. When reoxygenation was limited, the decrease of radiation effect occurred due to SLDR.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
