Exposure to Cerium Oxide Nanoparticles Is Associated With Activation of Mitogen-activated Protein Kinases Signaling and Apoptosis in Rat Lungs / 예방의학회지

OBJECTIVES: With recent advances in nanoparticle manufacturing and applications, potential exposure to nanoparticles in various settings is becoming increasing likely. No investigation has yet been performed to assess whether respiratory tract exposure to cerium oxide (CeO2) nanoparticles is associated with alterations in protein signaling, inflammation, and apoptosis in rat lungs. METHODS: Specific-pathogen-free male Sprague-Dawley rats were instilled with either vehicle (saline) or CeO2 nanoparticles at a dosage of 7.0 mg/kg and euthanized 1, 3, 14, 28, 56, or 90 days after exposure. Lung tissues were collected and evaluated for the expression of proteins associated with inflammation and cellular apoptosis. RESULTS: No change in lung weight was detected over the course of the study; however, cerium accumulation in the lungs, gross histological changes, an increased Bax to Bcl-2 ratio, elevated cleaved caspase-3 protein levels, increased phosphorylation of p38 MAPK, and diminished phosphorylation of ERK-1/2-MAPK were detected after CeO2 instillation (p<0.05). CONCLUSIONS: Taken together, these data suggest that high-dose respiratory exposure to CeO2 nanoparticles is associated with lung inflammation, the activation of signaling protein kinases, and cellular apoptosis, which may be indicative of a long-term localized inflammatory response.

Effects of doping with CeO[2] and calcination temperature on physicohcemical properties of NiO/Al[2]O[3] system

The effects of doping with CeO[2] and calcinations temperature on physicochemical properties of NiO/Al[2]O[3] system have been investigated using DTA, XRD, nitrogen adsorption measurements at - 196 [degree sign] C techniques and decomposition of H[2]O[2] at 30-50 [degree sign] C. The pure and variously doped mixed solids were subjected to heat treatment at 300, 400, 700, 900 and 1000 [degree sign] C. The amounts of dopant were 0.75, 1.5 and 3 mol% CeO[2]. The results revealed that the presence of NiO with aluminium oxide much enhanced the degree of crystallinity of the gamma-Al[2]O[3] phase. In contrast, the presence of Al[2]O[3] much retarded the crystallization process of the NiO phase. The specific surface areas were found to increase with increasing calcinations temperature from 300 to 400 [degree sign] C and with doping of the system under investigation with CeO[2]. The pure and variously doped solids, calcined at 300 and 400 [degree sign] C, were constituted of amorphous NiO dispersed in gamma-Al[2]O[3] Heating at 700[degree sign] C resulted in formation of poorly crystalline NiO and gamma-Al[2]O[3] phases beside CeO[2] for the doped solids. Crystalline NiAl[2]O[4] phase was formed starting from 900[degree sign] C as a result of solid-solid interaction between the reacted oxides. The degree of crystallinity of NiAl[2]O[4] increased with increasing the calcinations temperature from 900 to 1000 [degree sign]. An opposite effect was observed upon doping with CeO[2]. NiO/Al[2]O[3] system calcined at 300 and 400 [degree sign] has catalytic activity higher than individual NiO obtained at the same calcinations temperature. The catalytic activity of NiO/Al[2]O[3] system increased, progressively, with increasing the amount of CeO[2] dopant. The doping process did not modify the mechanism of the catalyzed reaction but changed the concentration of active sties without changing their energetic nature