Peel M, Marczynski B, Baur X
Department of Biology, Carleton University, Ottawa, Ontario, Canada.
J Toxicol Environ Health. 1997 Dec 26;52(6):517-26. doi: 10.1080/00984109708984078.
Inhalation of diisocyanate vapors is associated with immediate-type hypersensitivity reactions and direct toxic responses. The genotoxic effects of diisocyanates have not been clarified. The aim of this study was to examine the changes in DNA following in vitro exposure to three most commonly used diisocyanates (toluene diisocyanate, TDI; methylenediphenyl-4,4'-diisocyanate, MDI; and hexamethylene diisocyanate, HDI) and to compare their binding potential using melting behavior of DNA and electrophoresis studies in DNA. Following incubation of DNA with MDI (pure and mix) and HDI we found no differences in the melting behavior compared to the control calf thymus DNA. However, DNA treated with TDI showed differences in the shape of the native DNA curves due to changes in hyperchromicity and exhibited 14% more DNA reconstitution after renaturation. The small changes in the melting behavior of native DNA do not suggest the formation of DNA intrastrand cross-links but rather conformational changes of single- and double-stranded DNA. These conformational changes were further explored by agarose electrophoresis of native and denatured calf thymus DNA. Control and all diisocyanate-exposed DNA showed no differences in the size of native DNA fragments. Conversely, electrophoresis of TDI mix-incubated DNA, following denaturation, showed a distinct reduction in the double-stranded DNA fragment size compared to the control, MDI-denatured (pure and mix), and HDI-denatured DNA. These findings may help to better understand the mechanisms of the genotoxic effect of TDI.
吸入二异氰酸酯蒸汽与速发型超敏反应和直接毒性反应有关。二异氰酸酯的遗传毒性作用尚未阐明。本研究的目的是检测体外暴露于三种最常用的二异氰酸酯（甲苯二异氰酸酯，TDI；亚甲基二苯基-4,4'-二异氰酸酯，MDI；和六亚甲基二异氰酸酯，HDI）后DNA的变化，并利用DNA的熔解行为和电泳研究比较它们的结合潜力。将DNA与MDI（纯品和混合物）和HDI孵育后，我们发现与对照小牛胸腺DNA相比，熔解行为没有差异。然而，用TDI处理的DNA由于增色性变化而在天然DNA曲线形状上表现出差异，并且复性后DNA重构增加了14%。天然DNA熔解行为的微小变化并不表明形成了DNA链内交联，而是单链和双链DNA的构象变化。通过天然和变性小牛胸腺DNA的琼脂糖电泳进一步探究了这些构象变化。对照和所有暴露于二异氰酸酯的DNA在天然DNA片段大小上没有差异。相反，与对照、MDI变性（纯品和混合物）和HDI变性DNA相比，TDI混合物孵育的DNA变性后电泳显示双链DNA片段大小明显减小。这些发现可能有助于更好地理解TDI遗传毒性作用的机制。
