EVALUATION OF BRONCHOALVEOLAR LAVAGE PROFILING AS A SCREENING METHOD FOR PULMONARY DAMAGE INDUCED BY NITROGEN-DIOXIDE, FLY ASH, AND NITROGEN-DIOXIDE - FLY ASH COMBINATIONS
Abstract
Bronchoalveolar lavage fluid profiling (BALP) was used to detect pulmonary injury induced by acute inhalation of NO(,2) gas and fly ash alone and in combination. Also, BALP was utilized in an investigation into potential NO(,2)-fly ash synergism. The components measured in the BALP included lactate dehydrogenase, glucose-6-phosphate dehydrogenase, acid phosphatase, (beta)-glucuronidase, alkaline phosphatase, glutathione peroxidase, and glutathione reductase activity levels, sialic acid and total protein contents, and total and differential cell counts. BALP analysis was effective in detecting the multifocal necrotizing terminal bronchiolitis produced in three groups of hamsters exposed to increasing concentrations of NO(,2) gas (12, 17 and 22 ppm) for 48 continuous hours. BALP and histopathologic changes correlated well and followed a dose-related pattern. Increased numbers of neutrophils and macrophages were the most sensitive BALP indicators of NO(,2) damage. To evaluate the potential acute toxic effects of fly ash, three groups of hamsters were exposed to increasing concentrations of fly ash alone (0, 69, and 123 mg/m('3)). No significant BALP or histopathologic alterations were observed. To evaluate potential NO(,2)-fly ash synergism, three groups of hamsters were exposed to 0, 12, and 17 ppm NO(,2) for 48 continuous hours with the addition of 0, 115, and 105 mg/m('3) fly ash respectively during the initial 6 hours. No consistent significant BALP difference between hamsters exposed to NO(,2) + fly ash and NO(,2) alone were observed. However, lesions at the light microscopic level revealed significantly greater changes in NO(,2) + fly ash exposed hamsters. To further evaluate synergistic effects between these two inhalants, the acute inhalation (48 continuous hours) LC(,50) of NO(,2) gas alone and in combination with fly ash were determined and estimated to be 36 and 31 ppm respectively, which represented a slight but insignificant decrease in the NO(,2) + fly ash group. In summary, BALP was proven effective in detecting pulmonary injury induced by acute NO(,2) and NO(,2) + fly ash inhalation. Also, no false BALP indication of damage was found in fly ash alone exposures. However, BALP was not sensitive enough to detect the subtle NO(,2)-fly ash synergism as evidenced by histopathologic evaluation of tissues.
Degree
Ph.D.
Subject Area
Veterinary services
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