PLEURAL DOSIMETRY AND BIOMARKERS OF RESPONSE TO FIBERS

职业性接触石棉纤维与增加 发生间皮瘤、胸膜恶性肿瘤的风险 或腹膜衬里。过去石棉的广泛使用提高了 公众担心环境暴露也可能导致间皮瘤。 暴露后发生恶性间皮瘤的风险评估 对石棉或其他纤维来说是困难的，因为纤维的最小剂量 产生这些肿瘤所需的条件尚不清楚。当前的啮齿动物模型 间皮瘤并不令人满意，因为它们使用极高剂量的 直接通过腹膜或胸膜腔内注射的纤维 而不是吸入。拟议研究的目标是 建立一种新的动物模型以确定生物有效剂量 启动青石棉开发所需的石棉纤维 间皮瘤。纤维剂量测量将表示为 使用组织在胸膜衬里沉积并持续存在的纤维 消化、透射电子显微镜和视频增强 差示干涉对比光学显微镜观察纤维的研究 潜在的目标细胞群体(具体目标1)。两种回应 潜在的靶细胞将被确认为特异和敏感的生物细胞 对沉积在胸膜中的石棉纤维的反应标志物。第一, 石棉纤维诱发染色体损伤的分子标记将是 利用生物素化DNA探针和原位杂交技术开发。一只老鼠 着丝粒DNA探针将用于检测染色体非整倍体和 结构异常。P53抑癌基因杂合性缺失 用间接免疫荧光法对中期染色体进行基因定位 扩散和相间核(具体目标2)。第二，数量上的 间皮细胞损伤和增殖的标志物将被开发 使用形态测量法(具体目标3)。纤维剂量学与生物标志物 将比较胸腔内注射和胸膜内注射后的反应 吸入青石棉纤维。这些实验将评估 纤维沉积的数量之间是否存在相关性 胸膜，它们的持久性，以及人口倍增的次数 恶性间皮瘤出现前的组织学表现(特定目标 #4和5)。最终，这个新的模型可以用来推断 人体暴露于石棉和人造石棉的剂量-反应关系 矿物纤维，以便更准确地评估发展的风险 恶性间皮瘤。

Occupational exposure to asbestos fibers is associated with an increased risk of developing mesotheliomas, malignant tumors arising from the pleural or peritoneal linings. Widespread use of asbestos in the past raises public concern that environmental exposure may also produce mesotheliomas. Assessment of the risk of developing malignant mesothelioma after exposure to asbestos or other fibers is difficult because the minimum dose of fibers required to produce these tumors is unknown. Current rodent models of mesothelioma are unsatisfactory because they use extremely high doses of fibers delivered directly by intraperitoneal or intrapleural injection instead of inhalation. The objective of the proposed research is to develop a new animal model to determine the biologic effective dose of crocidolite asbestos fibers required to initiate the development of mesotheliomas. Fiber dosimetry will be expressed as the total number of fibers that deposit and persist in the pleural lining using tissue digestion, transmission electron microscopy, and video-enhanced differential interference contrast light microscopy to visualize fibers in potential target cell populations (Specific Aim #1). Two responses of potential target cells will be validated as specific and sensitive biologic markers of response to asbestos fibers deposited in the pleura. First, molecular markers for chromosomal damage induced by asbestos fibers will be developed using biotinylated DNA probes and in-situ hybridization. A mouse centromeric DNA probe will be used to detect chromosomal aneuploidy and structural aberrations. Loss of heterozygosity at the p53 tumor suppressor gene locus will be visualized by indirect immunofluorescence on metaphase spreads and interphase nuclei (Specific Aim #2). Second, quantitative markers of mesothelial cell injury and proliferation will be developed using morphometry (Specific Aim #3). Fiber dosimetry and biologic markers of response will be compared following intrapleural injection and inhalation of crocidolite asbestos fibers. These experiments will assess whether there is a correlation between the number of fibers deposited in the pleura, their persistence, and the number of population doubling times before the histologic appearance of malignant mesothelioma (Specific Aims #4 and 5). Ultimately, this new model could be used to extrapolate dose-response relationships to human exposure to asbestos and man-made mineral fibers in order to assess more accurately the risk of developing malignant mesotheliomas.