IRON AND ASBESTOS-INDUCED DNA DAMAGE

这项研究的假设是，铁是导致 矿物纤维的致癌性。 纤维可以具有内在的铁， 例如青石棉，或者可以获得结合到表面的铁。 要么 内在的或后天获得的铁可能是活跃的表面，但动员 可以增加铁与O2的反应性，产生自由基， 会导致中毒和癌症 体外实验将集中在 两种方法对溶液或培养的巨噬细胞铁结合的影响 含铁量高的石棉、青石棉和铁石棉，以及 致癌矿物，含铁很少或没有，毛沸石。 四个参数 将被监测：表面成分和地形，表面 氧化还原活性，螯合剂的铁动员速率，以及 诱导铁催化DNA单链断裂的能力。表面 成分和形貌将通过X射线光电子 光谱学、俄歇电子光谱学和扫描力显微镜。 表面氧化还原活性铁的量将使用介导， 薄层电池循环伏安法 细胞内分布 中子活化青石棉中~（55）Fe在人肺上皮细胞中的分布 间皮细胞将与[55 Fe]转铁蛋白， 无毒铁源和有毒铁源[55 Fe]NTA。 的 10，000 x g上清液中的55 Fe量，在免疫沉淀中， 铁蛋白，血红素中，<10，000 MW级分（LMW）和亚细胞中 细胞器将被确定。 LMW螯合剂的性质将是 使用激光解吸飞行时间质谱法测定，质子 核磁共振和高效液相色谱法。 从中子活化的铁中动员成LMW形式的铁的量 青石棉，铁石棉，或毛沸石，卸载或装载铁，将是 比较它们与细胞毒性和铁蛋白合成的关系。

The hypothesis for the proposed research is that iron is responsible for the carcinogenicity of mineral fibers. Fibers can have intrinsic iron, e.g. crocidolite, or can acquire iron which binds to the surface. Either intrinsic or acquired iron may be active at the surface, but mobilization may increase the reactivity of the iron with O2 generating radicals that can cause toxicity and cancer. The in vitro experiments will focus on the effects of iron binding from solution or from cultured macrophages by two forms of asbestos of high iron content, crocidolite and amosite, and a carcinogenic mineral with little or no iron, erionite. Four parameters will be monitored: the surface composition and topography, the surface redox activity, the rate of iron mobilization by chelators, and the ability to induce iron-catalyzed DNA single-strand breaks. The surface composition and topography will be characterized by X-ray photoelectron spectroscopy, Auger electron spectroscopy, and scanning force microscopy. The amount of surface redox active iron will be determined using mediated, thin-layer cell cyclic voltammetry. The intracellular distribution of 55Fe from neutron activated crocidolite in human lung epithelial and mesothelial cells will be compared with that from [55Fe]transferrin, a nontoxic source of iron, and [55Fe]NTA, a toxic source of iron. The amounts of 55Fe in the 10,000 x g supernatant, in immunoprecipitated ferritin, in heme, in <10,000 MW fraction (LMW), and in subcellular organelles will be determined. The nature of the LMW chelator will be determined using laser desorption time-of-flight mass spectrometry, proton nuclear magnetic resonance, and high performance liquid chromatography. The amounts of iron mobilized into the LMW form from neutron-activated crocidolite, amosite, or erionite, unloaded or loaded with iron, will be compared for their relationship with cytotoxicity and ferritin synthesis.