Fig. 9
Lpo and Mmp12 levels in alveolar tissue. Rats were exposed to clean air, 3.0 mg/m3 CeO2 nanoparticles or 50.0 mg/m3 BaSO4 nanoparticles. a Lpo and b Mmp12 levels were determined immunohistochemically after one, 28 and 90 days exposure. Values are expressed as positive area per total tissue, normalized to the control group, mean + SD, *p < 0.05 vs. clean air control, n ≤ 5; Kruskal–Wallis–ANOVA with Mann–Whitney U-test as post hoc analysis