Tisljar-Lentulis G, Henneberg P, Feinendegen L E, Commerford S L
Radiat Res. 1983 Apr;94(1):41-50.
The effect of oxygen, expressed as the oxygen enhancement ratio (OER), on the number of single-strand breaks (SSB) and double-strand breaks (DSB) induced in DNA by the radioactive decay of tritium was measured in human T1 cells whose DNA had been labeled with tritium at carbon atom number 6 of thymidine. Decays were accumulated in vivo under aerobic conditions at 0-1 degrees C and at -196 degrees C and in a nitrogen atmosphere at 0-1 degrees C. The number of SSB and DSB produced was analyzed by sucrose gradient centrifugation. For each tritium decay there were 0.25 DSB in cells exposed to air at 0-1 degrees C and 0.07 in cells kept under nitrogen, indicating an OER of 3.6, a value expected for such low-LET radiation. However, for each tritium decay there were 1.25 SSB in cells exposed to air at 0-1 degrees C and 0.76 in cells kept under nitrogen indicating an OER of only 1.7. The corresponding values for 60Co gamma radiation, expressed as SSB per 100 eV absorbed energy, were 4.5 and 1.0, giving an OER of 4.5. The low OER value found for SSB induced by tritium decay can be explained if 31% of the total SSB produced in air result from transmutation by a mechanism which does not produce DSB and is unaffected by oxygen.
在DNA的胸腺嘧啶第6位碳原子用氚标记的人T1细胞中，测定了以氧增强比（OER）表示的氧对氚放射性衰变诱导的DNA中单链断裂（SSB）和双链断裂（DSB）数量的影响。衰变在0 - 1℃和-196℃的有氧条件下以及在0 - 1℃的氮气气氛中体内累积。通过蔗糖梯度离心分析产生的SSB和DSB数量。对于每次氚衰变，在0 - 1℃暴露于空气中的细胞中有0.25个DSB，在氮气中保存的细胞中有0.07个DSB，表明OER为3.6，这是这种低传能线密度辐射预期的值。然而，对于每次氚衰变，在0 - 1℃暴露于空气中的细胞中有1.25个SSB，在氮气中保存的细胞中有0.76个SSB，表明OER仅为1.7。以每100 eV吸收能量的SSB表示的60Coγ辐射的相应值为4.5和1.0，OER为4.5。如果空气中产生的总SSB中有31%是由一种不产生DSB且不受氧影响的嬗变机制产生的，那么就可以解释氚衰变诱导的SSB的低OER值。
