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CARBONYL CONTENT OF DIESEL EXHAUST FROM TWO SOURCES AND POSSIBLE IMPLICATIONS FOR CELL RESPONSES
Citation:
Madden, M. C., J. Stonehuerner, AND L. A. Dailey. CARBONYL CONTENT OF DIESEL EXHAUST FROM TWO SOURCES AND POSSIBLE IMPLICATIONS FOR CELL RESPONSES. Presented at Society of Toxicology, Nashville, TN, March17-21, 2001.
Description:
Diesel exhaust is known to cause health effects including increases in lung inflammation and altered immunological parameters. The diesel exhausts used in our studies were collected into ice-cooled PBS from a diesel engine running at idle speed (DE2A) or at full load (DE5A). Previous work has shown that DE5A causes more cytotoxicity and greater increases in inflammatory mediators in cultured human airway epithelial cells than DE2A. Some carbonyls are cytotoxic to epithelial cells and increase inflammatory mediator production. We therefore examined whether the carbonyl content of the exhausts were involved in the responses of the epithelial cells to diesel exhaust exposure. A method was developed for simultaneous determination of C2 to C12 aldehydes by HPLC/MS. Diesel exhausts were derivatized with 2,4-dinitrophenylhydrazine and derivatives isolated by hexane extraction and evaporation under nitrogen. Using quantitation of the peak at 365 nm in the UV/VIS spectra as an indication of the total level of carbonyl compounds in the reconstituted extracts, DE2A was found to contain a >10X higher level of total carbonyl compounds than DE5A, indicating an inverse correlation between toxicity and total carbonyl content. Reconstituted extracts were injected into an HPLC/MS with a C18 column using ESI negative ion detection with selective ion monitoring. HPLC/MS results were consistent with the UV/VIS result in that levels of polar aldehydes with retention times (RT) similar to C2 to C4 averaged ~10X higher in DE2A than in DE5A. However, DE5A contained higher levels of intermediate polarity aldehydes with RT similar to C7 to C10 than did DE2A. These data suggest that carbonyls of intermediate polarity in the diesel exhausts may be important in epithelial cell-mediated responses of the. These observations underscore the importance of sensitive and selective analytical methods such as HPLC/MS in linking components of complex mixtures to biological effects. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.