Silva C R, Valsa J O, Caniné M S, Caldeira-de-Araújo A, Bernardo-Filho M
Departamento de Biofísica e Biometria, Universidade do Estado do Rio de Janeiro, Brazil.
Yale J Biol Med. 1998 Jan-Feb;71(1):7-14.
Technetium-99m (99mTc) has been used in nuclear medicine and in biomedical research to label molecular and cellular structures employed as radiotracers. Here, we have evaluated, on a DNA repair proficient Escherichia coli strain, the 99mTc decay inactivation and the influence of the (i) pre-treatment with metal ion chelators or of the (ii) treatment with a free radical scavenger on the protection of the cells against the lethal effect of the 99mTc. As SnCl2 is frequently used as a reducing agent in the 99mTc-labeling process, we have also studied the capability of SnCl2 to alter the biological effects induced by the 99mTc decay. As we are exposed to either chemical or physical agents in the nature, we have decided to study a possible influence of the ultraviolet solar radiation in the biological phenomena induced by the 99mTc decay. Our data point out (i) a very important role of the Auger and/or conversion electrons in the cytotoxicity induced by the 99mTc decay; (ii) SnCl2, the metal ion chelators and the free radical scavenger protect the cells against the lethal effect of the 99mTc; and (iii) near-UV does not alter the lethal effect of the 99mTc decay.
锝-99m（99mTc）已被用于核医学和生物医学研究，以标记用作放射性示踪剂的分子和细胞结构。在此，我们在DNA修复能力正常的大肠杆菌菌株上评估了99mTc衰变失活情况，以及（i）用金属离子螯合剂预处理或（ii）用自由基清除剂处理对细胞抵御99mTc致死效应的影响。由于SnCl2在99mTc标记过程中常被用作还原剂，我们还研究了SnCl2改变99mTc衰变诱导的生物学效应的能力。鉴于我们在自然界中会接触到化学或物理因素，我们决定研究太阳紫外线辐射对99mTc衰变诱导的生物学现象可能产生的影响。我们的数据表明：（i）俄歇电子和/或内转换电子在99mTc衰变诱导的细胞毒性中起非常重要的作用；（ii）SnCl2、金属离子螯合剂和自由基清除剂可保护细胞免受99mTc的致死效应；（iii）近紫外线不会改变99mTc衰变的致死效应。
