Ogami Akira, Morimoto Yasuo, Yamato Hiroshi, Oyabu Takako, Kajiwara Takayoshi, Tanaka Isamu
Department of Environmental Health Engineering, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan.
Inhal Toxicol. 2004 Oct-Nov;16(11-12):793-800. doi: 10.1080/08958370490476749.
We evaluate the morphometric point counting method (PCM) for qualitatively analyzing pulmonary inflammation and collagen deposits (i.e., fibrosis) in the assessment of the biological hazards of inhaled respirable particles at a realistic dose comparable to that of exposure in the work environment. Rats were exposed by intratracheal instillation to a 2-mg dose, which is close to the estimated overdose at which macrophage clearance is impared, of each of 3 kinds of particulate matter: crystalline silica, crocidolite asbestos, and titanium dioxide. The lung tissue was evaluated at 3 days, 1 wk, and 1, 3, and 6 mo after exposure. Digital images taken of the lung tissue after processing and staining of the lung sections were examined by the PCM under light microscopy. Evidence of inflammation along with progressive inflammatory changes occurred with crystalline silica and crocidolite, which are well-known hazardous particle types. In contrast, lung tissue from rats exposed to titanium dioxide particles demonstrated a decreasing pattern of histopathological change with increasing retention time. Differences in repair patterns of TiO(2) versus crocidolite and silica following the 2-mg dose exposure suggest that the PCM scoring system may be a useful and sensitive tool for qualitatively evaluating the biological hazards of new particle types, for which no toxicological information exists for low-dose exposure, by using the results from assessment of fibrogenic particle types (such as crocidolite and crystalline silica) as well as particle types with low toxicity (such as TiO(2)) as reference points.
我们评估形态计量学点计数法（PCM），用于在与工作环境中暴露剂量相当的实际剂量下，定性分析吸入可吸入颗粒物的生物危害时的肺部炎症和胶原沉积（即纤维化）。通过气管内滴注，使大鼠暴露于2毫克剂量的3种颗粒物中的每一种：结晶二氧化硅、青石棉和二氧化钛，该剂量接近估计的巨噬细胞清除功能受损的过量剂量。在暴露后3天、1周以及1、3和6个月对肺组织进行评估。在光学显微镜下，通过PCM检查肺切片处理和染色后拍摄的肺组织数字图像。结晶二氧化硅和青石棉（已知的有害颗粒类型）出现了炎症迹象以及渐进性炎症变化。相比之下，暴露于二氧化钛颗粒的大鼠的肺组织显示出组织病理学变化随滞留时间增加而减少的模式。2毫克剂量暴露后，二氧化钛与青石棉和二氧化硅的修复模式差异表明，PCM评分系统可能是一种有用且敏感的工具，通过将纤维生成性颗粒类型（如青石棉和结晶二氧化硅）以及低毒性颗粒类型（如二氧化钛）的评估结果作为参考点，来定性评估新颗粒类型的生物危害，对于这些新颗粒类型，尚无低剂量暴露的毒理学信息。
