RESUMO
Male guinea pigs were exposed to 750ppm or l000ppm or 1 500ppm toluene (8h/d, for 14d), and their hearing thresholds were tested by means of Madsen ERA 2250 system 3d and 14d after exposure. Hearing impairment was observed in all groups. The degree of impairment was related to the exposure concentration and had a tendency to further damage in two weeks. The results indicate that toluene can cause acute hearing impairment even if its concentration is as low as 750ppm and the impairment develops from bad to worse at least in two weeks.
RESUMO
Objective:[WT5BZ] The effects of exogenous vitamin C (VC) and glutathione (GSH) on ultraweak spontaneous luminescence of culturing pulmonary alveolus macrophages from rabbits were studiesd. [WT5FZ]Methods:[WT5BZ] In a special thermostat, which was passed through by airs with various concentrations of oxygen, the alveolar macrophages (AMs) were cultured in DMEM medium with VC or GSH, and the spontaneous luminescence of culturing AMs was examined by a luminometer. [WT5FZ]Results:[WT5BZ] when VC in medium was over 0.3 mmol/L, it could significantly enhance the oxidative luminescence of cells exposed to O 2 and cell death was resulted. However, when the cells were exposed to air without O 2 there was no significant effect. On the contrary,the lower concentration of VC (0.03 mmol/L) as well as GSH could reduce the spontaneous luminescence of cells exposed to a high concentration (99.1%) of O 2 in air. [WT5FZ]Conclusion:[WT5BZ] The results show that the spontaneous oxidation of culturing cells is an important reason for the ultraweak luminescence. High concentration of VC can promote cellular oxidative damage in vitro, but the exogenous GSH has a protective effect against oxidization in culturing cells.