The antioxidant effects of copper sulphate on the actions of a phorbol ester and a xanthine-xanthine oxidase superoxide-anion generating system in murine epidermal cells

Environmental and health impacts of fine and ultrafine metallic particles: assessment of threat scores

This study proposes global threat scores to prioritize the harmfulness of anthropogenic fine and ultrafine metallic particles (FMP) emitted into the atmosphere at the global scale. (Eco)toxicity of physicochemically characterized FMP oxides for metals currently observed in the atmosphere (CdO, CuO, PbO, PbSO(4), Sb(2)O(3), and ZnO) was assessed by performing complementary in vitro tests: ecotoxicity, human bioaccessibility, cytotoxicity, and oxidative potential. Using an innovative methodology based on the combination of (eco)toxicity and physicochemical results, the following hazard classification of the particles is proposed: CdCl2~CdO>CuO>PbO>ZnO>PbSO(4)>Sb(2)O(3). Both cadmium compounds exhibited the highest threat score due to their high cytotoxicity and bioaccessible dose, whatever their solubility and speciation, suggesting that cadmium toxicity is due to its chemical form rather than its physical form. In contrast, the Sb(2)O(3) threat score was the lowest due to particles with low specific area and solubility, with no effects except a slight oxidative stress. As FMP physicochemical properties reveal differences in specific area, crystallization systems, dissolution process, and speciation, various mechanisms may influence their biological impact. Finally, this newly developed and global approach could be widely used in various contexts of pollution by complex metal particles and may improve risk management.

Effects of N-acyl dehydroalanines on phorbol ester-elicited tumor development and other events in mouse skin

The free radical scavengers N-acyl dehydroalanines (AD compounds) were examined for their effect on several 12-O-tetradecanoylphorbol-13-acetate (TPA) elicited events in mouse skin. The induction of oxidant production by TPA in isolated mouse epidermal cells was reduced by approximately 70% by 1 mM paramethoxyphenyl-acetyl dehydroalanine (AD5) and 80% by 1 mM parasulfoxyphenyl-acetyl dehydroalanine (AD19). These AD compounds also completely suppressed the TPA-dependent stimulation of prostaglandin E2 synthesis in primary cultures of epidermal cells. Single and multiple topical applications on the dorsal skin of SENCAR mice of either AD5 or AD 19 inhibited TPA-induced epidermal hyperplasia but failed to inhibit epidermal ornithine decarboxylase induction. When used with TPA on initiated mice, AD19 did not inhibit papilloma formation; however, after 40 weeks of promotion, the carcinoma incidence was reduced by 50% in the AD19 group. These results suggest that reactive oxygens may be more important to the conversion of benign to malignant tumors than in the initial development of the benign tumors.