Table 1

 Median DNA damage measured by the standard comet assay and the Fapy-DNA-glycosylase- modified comet assay before and after methylene blue and indigo carmine dye spraying in the two groups of patients

Patient groupnMedian DNA damage (IQR) before spraying (%)Median DNA damage (IQR) after spraying (%)p Value (Wilcoxon’s test)
FPG, Fapy-DNA-glycosylase; IC, indigo carmine; IQR, interquartile range; MB, methylene blue.
Biopsy samples were digested with 100 µl of 0.5% pronase and 100 µl of 0.3% collagenase in 800 µl DMEM at 37°C for 1 h, to create a single-cell suspension for comet assay analysis.
IC spraying (standard comet assay)107.2 (5.1–15.8)5.3 (4.1–11.7)0.084
IC spraying (FPG-modified comet assay)10.5 (6.0–32.1)12.3 (5.9–17.3)0.492
MB spraying (standard comet assay)105.9 (4.9–8.1)12.0 (5.2–19.8)0.014
MB spraying (FPG-modified comet assay)9.8 (7.5–14.0)34.3 (23.9–58.8)0.002