No abstract

No abstract

Diesel exhaust particulate material (DPM) was assayed for induction of chromosomal aberrations (CA), micronucleus (MN) formation, and 6-thioguanine-resistant (TG9 gene mutation in V79 cells as a dispersion in dipalmitoyl phosphatidylcholine (DPPC) in physiological saline, a simulated pulmonary surfactant. Filter-collected automobile DPM provided for the study was not organic solvent extracted, but was directly mixed into DPPC in saline dispersion as a model of pulmonary surfactant conditioning of a soot particle depositing in a lung alveolus. A statistically significant difference was found between treated and control groups at all concentrations tested in a CA assay. Assay for MN induction also gave a positive response: Above 50 microg/ml, the frequencies of micronucleated cells (MNC) were about 2 times higher than those in the control group. The forward gene mutation assay did not show a positive response when cells were treated with up to 136 microg DPM/ml for 24 h, as dispersion in DPPC in saline. Some comparison assays were run on direct dispersions of the DPM into dimethyl sulfoxide, with results equivalent to those seen with a DPPC-saline preparation: DPM in dimethyl sulfoxide (DMSO) was positive for MN induction but was negative for forward gene mutation in V79 cells. The positive clastogenicity results are consistent with other studies of DPM dispersed into DPPC-saline surfactant that have shown activity in mammalian cells for sister chromatid exchange, unscheduled DNA synthesis, and MN induction. The forward gene mutation negative results are consistent with studies of that assay applied to V79 cells challenged with DPM solvent extract.

Micronucleus formation and chromosomal aberration (CA) in V79 cells were compared for their sensitivity in response to ethylene oxide (EtO) treatment. The results indicate that EtO exposure for 30 min induced CAs in V79 cells at the concentration of 3,500 ppm or higher. A statistically significant difference (P less than 0.01) was found between treated and control groups at all concentrations tested based on percent aberrant cells. The increase was dose-dependent with a correlation coefficient of 0.88. The aberrations found include chromatid and isochromatid breaks, fragments, minutes, and exchanges. Results of the micronucleus assay both in mononucleated and binucleated cells showed a slight but not statistically significant increase in micronuclei with doses between 457 to 4115 ppm. At the highest concentration tested (12344 ppm) EtO caused a significant increase in the micronucleus frequency (P less than 0.05).

No abstract