The sizes of the alveolar macrophage (AM) and interstitial macrophage (IM) populations in the lungs of adult Fischer-344 rats were determined during steady state. AM labeled with opsonized erythrocytes during an in situ phagocytic assay were lavaged from excised lungs. The lungs were then dispersed into single-cell suspensions with collagenase and mechanical agitation, and the remaining mononuclear phagocytes were identified following a second labeling step. The size of the AM population was 1.3 X 10(7) cells, or approximately equal to 3% of the total lung cell population. The AM were negative for cytoplasmic myeloperoxidase granules. The size of the IM population was 8 X 10(6) cells, or approximately equal to 2% of the total lung cell population. IM were also negative for myeloperoxidase and, like AM, demonstrated marked Fc gamma R-mediated phagocytic activity. The high cell yields (approximately equal to 4 X 10(8) cells/lung; viability, greater than 85%) and the percentages of type II cells (11%) and ciliated epithelial cells (less than 0.5%) indicated the enzymatic dispersion method resulted in a highly efficient and representative sampling of the lung parenchyma. The collagenase method used in this study to disperse the lung cells into single-cell suspensions, in conjunction with additional cell separation techniques, may be of potential use for isolating enriched populations of IM, as well as other lung cell types, for in vitro study.

Min-U-Sil5, a form of alpha quartz, has been shown to induce peripheral lung tumors in rats exposed to the dust by inhalation. The animals were exposed to a nominal particle concentration of 12.4 mg/m3 for 8 hr/day, 4 days/week, for 2 years. The induced tumors were large and peripheral, and, when examined by electron microscopy, were found to be composed predominantly of alveolar type II cells. These cells were found in papillary, acinar, and solid forms of the tumors and were characterized by lamellar inclusion bodies. This is in contrast to the mouse, in which the papillary form was associated with Clara cells and the acinar form was linked with the type II cell. In this study, the Clara cell was a minor component of the tumor mass. No clear risk is established in man linking silica exposure to increased lung tumor rates.

Seven rhesus monkeys (14 eyes) were exposed to 1064-nanometer radiation in single pulses of 25 to 35 picoseconds fromn a mode-locked Nd: YA G laser. Threshold injury resulted from single pulses with a mnean energy of 13 +/- 3 mnicrojoules. Electron microscopy of the retina revealed that damnage was highly localized in the photoreceptor and pigmented epithelial cells at the oluter retina. Membrane disruption, distorted outer segmtzents, and abnormnal melanin granules resembling fetal premelanosomnies were observed.

No abstract

This study assessed the relationship between nitrogen dioxide inhalation and the development of pulmonary emphysema and investigated how the severity of preexisting emphysema brought about by protease (elastase) instillation into the lung may be augmented by a subchronic exposure to a relatively high concentration of nitrogen dioxide. Lungs of adult Fischer-344 rats were evaluated for emphysematous changes after (1) a single intratracheal instillation of elastase (E), (2) a 25-d exposure to 35 ppm nitrogen dioxide (NO2), and (3) elastase instillation followed by 25-d exposure to 35 ppm NO2 (E + NO2). Rats instilled with sterile normal saline and subsequently exposed to filtered air served as a control group (NS). Residual volumes (RV) of the NO2 and NS groups were virtually identical, whereas the RV of the E and E + NO2 lungs (2.3 and 2.3 ml, respectively) were significantly greater than those of the NS and NO2 lungs (1.3 and 1.4 ml, respectively). Directionally similar changes in the excised lung volumes and total lung capacities were obtained with the E and E + NO2 groups; NO2 alone, however, did not alter these volumetric parameters. No differences in arterial blood gases and pH values, minute ventilation, or breathing frequencies were found among the experimental groups. The mean linear intercept values (MLI) obtained with the NS and NO2 exposed lungs were essentially identical with average values of approximately 62 micron. This morphometric parameter was substantially increased in the E- and E + NO2-exposed lungs; no significant differences, however, were found between the MLI values obtained with the E and E + NO2 lungs (approximately 95 and approximately 97 micron, respectively). From these data, as well as histologic examinations of lung sections for evidence of emphysema, we conclude that (1) a subchronic, moderately high level of NO2 exposure does not produce an irreversible emphysematous lesion in the rat model and (2) exposure of rats to 35 ppm for 25 d after elastase instillation into the lungs does not potentiate protease-induced emphysema or bring about a progression in preexisting emphysema.