Clayton G. Loosli

Ultrastructure of nerves and associated cells in bronchiolar epithelium of the mouse lung.

The nerves and their associated cells in the bronchiolar epithelium of the mouse lung were studied with the electron microscope. Single unmyelinated axons, some of which are enlarged and contain many small mitochondria, are closely associated with groups of specialized epithelial cells. These cells are identified by having numerous dense-cored granules in the basal cytoplasm. Portions of the apical surfaces of these cells are exposed to the bronchiolar lumen. The perinuclear cytoplasm contains bundles of branching microfilaments. Many of these cells bear a single cilium on their lateral surfaces adjacent to the bronchiolar lumen. These nerve-epithelial cell complexes probably function as sensory receptor units in the bronchioles.

Effects of Ozone on Cell Renewal in Pulmonary Alveoli of Aging Mice

Groups of aging male mice were exposed to different concentrations of ozone (O3) for six hours. Following exposure, the animals were killed at intervals of 1, 24, 48, and 72 hours. Prior to killing, cells synthesizing DNA were labeled with tritiated thymidine. Immediately after exposure, the number of cells that could be labeled with tritiated thymidine was significantly fewer than in the controls. Inhibition of cell labeling was approximately the same at each concentration of O3 tested. By 72 hours, most of the labeling indexes had increased, approaching or surpassing control levels. These results suggest that one of the initial responses of alveolar tissue to O3 is a reduction in DNA synthesis.

Pulmonary Changes in 7,000 Mice Following Prolonged Exposure to Ambient and Filtered Los Angeles Air

This report summarizes the incidence and appearance of lung tumors and pneumonitis in over 7,000 mice, following prolonged exposure to ambient as compared with filtered Los Angeles air. Mice in the ambient air colonies showed no difference in histologic appearance and no increase in incidence of lung tumors in two lung tumor susceptible and one lung tumor resistant strains; on the contrary, more lung adenomas in A/J mice were noted in the filtered air group. Acute bronchopneumonia and interstitial pneumonitis were qualitatively similar but quantitatively significantly more common in ambient air C57 black mice. The findings suggest that prolonged exposure to ambient Los Angeles air is associated in several strains of mice with an increased susceptibility to pulmonary infection but not to increased pulmonary neoplasia.

Airborne Influenza PR8-A Virus Infections in Actively Immunized Mice

Young adult white mice, immunized subcutaneously with formalized mouse-lung suspensions of influenza PR8-A virus (test mice), along with corresponding unimmunized (control) mice, were exposed to sublethal and highly lethal nebulized clouds of freshly harvested homologous virus. The control mice developed rapid and fatal pulmonary infections following exposure to the lethal cloud of virus and extensive and persisting pulmonary changes following exposure to sublethal clouds of virus. The test mice became only mildly ill and survived the lethal airborne infections, although the virus grew to high titer in the lungs. Pneumonic involvement was focal and confined to the bronchial air passages and adjacent alveoli. Resolution occurred and residual lung scarring was not seen in recovered mice. Circulating antibody, therefore, was highly effective not only in preventing death but residual lung pathology.

Electron-microscopic studies of the innervation of the pulmonary veins of the mouse

The innervation of the pulmonary veins was studied with electron microscopy. The adrenergic and cholinergic nerves were differentiated with potassium permanganate fixation. All three layers of the venous wall, namely, the tunica intima, media and adventitia, contained unmyelinated axons. Adrenergic and cholinergic axons were located near the cardiac muscle in the tunica media and near the smooth muscle in the tunica intima. The morphological relationships may explain the pharmacological and electrophysiological responses of the large pulmonary veins observed by others.

Histopathologic Findings in Rats Exposed to Ambient and Filtered Air

There is no significant difference in life span or weight at death of rats living in ambient vs filtered Los Angeles atmosphere; nor is there any discernible histologic effect upon lung tissue following prolonged exposure of rats to ambient Los Angeles atmosphere. There appears to be a more abrupt increase in the incidence of chronic nephritis male rats in ambient air, commencing at about 650 days of age, and the overall incidence of advanced chronic nephritis at spontaneous death is significantly greater in male rats exposed to ambient air. These findings raise the possibility that exogenous factors in the Los Angeles atmosphere may promote the development of this renal degenerative disease.

Postinfluenzal Pulmonary Lesions in Vitamin A Deficient Mice

There were no significant differences in lung virus growth and antibody responses in the NA, RA, and HA diet groups of mice. Epithelialization of the alveolar ducts and alveoli due to peripheral growth of regenerating bronchial epithelial cells was present in all postinfluenzal lesions regardless of diet. However, the postinfluenzal lesions in mice on an NA diet with no liver vitamin A showed extensive epithelial nodule formation with significantly more squamous metaplasia and keratinization than was seen in the lungs of mice on RA and HA diets. The importance of the vitamin A status of the mice in determining the extent of squamous metaplasia and keratinization in postinfluenzal lesions of mice was emphasized.