Factors influencing heterogeneity of radiation-induced DNA-damage measured by the alkaline comet assay

Radiation Oncology

Table 4 Correlation between %Tail DNA and variance

Factor	Changes of amount of
	%Tail DNA	Variance
Single irradiation vs. no irradiation	↑	↑
Single irradiation and repair	↓	↓
Double irradiation vs. no irradiation	↑	↑
Double irradiation and repair	↓	↓
Double vs. single irradiation (+/- repair)	No change	↑
Loss of antioxidants and chromatin	↑↑	↑↑
Addition of antioxidants	↓	↓

Positive correlation of %Tail DNA and variance according to measurements of Table 2 and 3 were indicated by arrows. The only measurements with no change in damage but increase in heterogeneity were comparisons of single vs. double fractionated irradiation. Therefore, this parameter could potentially work as a differentiator of radiation sensitivity.
Abbreviations: ↑↑= very strong increase, ↑=increase, ↓=decrease.

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