Free Radic Biol Med. 2003 Apr 15;34(8):1089-99. doi: 10.1016/s0891-5849(03)00041-8.
The European Standards Committee on Oxidative DNA Damage (ESCODD) was set up to resolve problems in the measurement of DNA oxidation that have resulted in varying estimates of the extent of this damage in humans. HeLa cells, sent to members for analysis, were either untreated, or treated with light in the presence of a photosensitizer to induce different amounts of 8-oxo-7,8-dihydroguanine (8-oxoGua) in DNA. Laboratories employing HPLC with electrochemical detection were able to measure the induced damage with similar efficiency; dose response gradients for seven of the eight sets of results were almost identical. GC-MS and HPLC-MS/MS, employed in three laboratories, did not convincingly detect the dose response. An alternative approach to measuring base oxidation employs the enzyme formamidopyrimidine DNA N-glycosylase (FPG) to convert 8-oxoGua to strand breaks, which are then measured by alkaline unwinding, alkaline elution, or the comet assay. Ten laboratories used this approach; five were able to detect the dose response in cells treated with photosensitizer plus light (at lower doses than for chromatographic methods, because the enzymic methods are more sensitive and less prone to spurious oxidation). Median values for 8-oxoGua (or FPG-sensitive sites) in untreated cells were 4.01 per 10(6) guanines for chromatographic methods, and 0.53 per 10(6) guanines for techniques based on FPG.
欧洲氧化DNA损伤标准委员会（ESCODD）的成立是为了解决DNA氧化测量中出现的问题，这些问题导致了对人类这种损伤程度的不同估计。分发给成员进行分析的HeLa细胞，要么未处理，要么在存在光敏剂的情况下接受光照，以在DNA中诱导不同量的8-氧代-7,8-二氢鸟嘌呤（8-氧代鸟嘌呤，8-oxoGua）。采用高效液相色谱电化学检测的实验室能够以相似的效率测量诱导损伤；八组结果中的七组剂量反应梯度几乎相同。三个实验室使用的气相色谱-质谱联用仪（GC-MS）和高效液相色谱-串联质谱联用仪（HPLC-MS/MS）未能令人信服地检测到剂量反应。测量碱基氧化的另一种方法是使用甲酰胺嘧啶DNA N-糖基化酶（FPG）将8-氧代鸟嘌呤转化为链断裂，然后通过碱性解旋、碱性洗脱或彗星试验进行测量。十个实验室使用了这种方法；五个实验室能够检测到用光敏剂加光照处理的细胞中的剂量反应（剂量低于色谱法，因为酶法更灵敏且不易出现假氧化）。对于色谱法，未处理细胞中每10⁶个鸟嘌呤的8-氧代鸟嘌呤（或FPG敏感位点）中位数为4.01，对于基于FPG的技术，该中位数为每10⁶个鸟嘌呤0.53。
