Repopulation in mouse oral mucosa: changes in the effect of dose fractionation.
OBJECTIVE
To define the fractionation effect, including the magnitude and kinetics of dose compensation, on days 3 and 8 after a single priming dose of 8 Gy.


METHODS
Graded radiation doses were given to the snouts of C3H/Neu mice in 1 to 5 fractions within a time period of < or = 36 h, or in four fractions with intervals from 5 min to 4 h. Each protocol was terminated by a top-up dose of 2.5 Gy to a 3 x 3 mm2 test area in order to precipitate the subclinical damage induced by the snout treatment and to generate the full dose response.


RESULTS
No significant increase in isoeffective dose by increasing fraction numbers or by increasing interfraction intervals could be detected at each time point after the priming treatment. This indicates that the effect of dose fractionation was entirely lost.


CONCLUSIONS
The loss of fractionation effect may be interpreted as a substantial impairment of the processes underlying recovery from sublethal damage as a consequence of a repopulation-inducing priming dose given 3 days or 8 days in advance.
Dörr
W
W
Klinik und Poliklinik für Strahlentherapie und Radioonkologie, Medizinische Fakultät Carl Gustav Carus der Technischen Universität, Dresden, UK.
Brankovic
K
K
Hartmann
B
B
D000818:Animals; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009061:Mouth Mucosa / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects*; D011833:Radiation Injuries, Experimental; D011836:Radiation Tolerance / Q000528:radiation effects; D012038:Regeneration / Q000528:radiation effects*; D012737:Sex Factors; D014059:Tongue / Q000166:cytology / Q000502:physiology / Q000528:radiation effects