Histological alterations in male A/J XXXX following nose-only exposure to @entity286 smoke.

@entity32 @entity286 @entity19 @entity5 @entity1373 @entity75 @entity4648
The incidence and multiplicity of grossly observed and microscopic lesions of the respiratory tract of A/J @entity19 exposed nose-only to mainstream smoke (50, 200, or 400 mg total particulate matter/m3 from 2R4F cigarettes) was compared to those of filtered air controls. Animals were necropsied at the end of exposure (5 mo) or following 4 or 7 mo of recovery. Lungs were visually inspected for @entity5 at all necropsies and examined histopathologically at 9 and 12 mo. At 5 mo no @entity5 were recorded. No significant elevations in @entity5 incidence or multiplicity were recorded although at 9 mo multiplicity was elevated in the mid-exposure group (0.90 versus 0.55 @entity5 per animal for controls). At 12 mo, multiplicity was increased over the 9-mo necropsy at all exposures except 200 mg/m3; however, there were no dose-related trends in multiplicity or incidence. Histopathological alterations included @entity1373 , @entity4648 , and @entity32 of the nose and larynx and proliferative lesions of the lungs. At 9 mo, the multiplicity of focal lung lesions was 1.4 per animal in controls but averaged 1.0 among smoke-exposed groups. There was an inverse relation (p < .059) between smoke concentration and the percentage of @entity75 at 9 mo. At 12 mo the high-exposure group had slightly increased multiplicity of 2.3 lesions compared with 1.6 among controls, while the percentage of hyperplasic lesions was similar between groups. Nose-only inhalation of mainstream @entity286 smoke resulted in chronic inflammatory changes of the respiratory tract yet failed to produce statistically significant changes in @entity5 incidence or multiplicity.
