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With the extensive application of titanium dioxide nanoparticles (TiO2 NPs), their impacts on calcium homeostasis have aroused extensive attention from scholars. However, there are still some controversies in relevant reports. Therefore, a systematic review was performed followed by a meta-analysis to explore whether TiO2 NPs could induce the imbalance in calcium homeostasis in vivo and in vitro through Revman5.4 and Stata15.0 in this research. Fourteen studies were included through detailed database retrieval and literature screening. Results indicated that the calcium levels were significantly increased and the activity of Ca2+-ATPase was significantly decreased by TiO2 NPs in vivo and in vitro. Subgroup analysis of the studies in vivo showed that TiO2 NPs exposure caused a significant increase in calcium levels in rats, exposure to large-sized TiO2 NPs (>10 nm) and long-term (>30 days) exposure could significantly increase calcium levels, and the activity of Ca2+-ATPase showed a concentration-dependent downward trend. Subgroup analysis of the studies in vitro revealed that intracellular calcium levels increased significantly in animal cells, exposure to small-sized TiO2 NPs (≤10 nm) and high concentration (>10 μg/mL) exposure could induce a significant increase in Ca2+ concentration, and the activity of Ca2+-ATPase also showed a concentration-dependent downward trend. This research showed that the physicochemical properties of TiO2 NPs and the experimental scheme could affect calcium homeostasis [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiNPs) have been widely used in nanotechnology, and more attention has been paid to their safety evaluation. However, there are still inconsistent conclusions about the genotoxicity of SiNPs. A systematic review was conducted to explore whether SiNPs have genotoxicity followed by a meta-analysis of in vivo and in vitro murine genotoxicity tests. A total of 26 eligible studies were identified in this meta-analysis through a detailed process of inclusion and exclusion, which included 9 in vivo studies, 15 in vitro studies, and 2 in both. The results of in vitro studies showed that SiNPs exposure significantly increased the indicators of the comet assay, such as tail DNA content (T DNA%), tail length (TL), and olive tail moment (OTM). Indicators of mutagenicity had not been affected in vitro studies, such as mutation frequency (MF) and micronucleus (MN) frequency. There was a significant increase in MN frequency, but there was no influence on T DNA% in vivo. Results of subgroup analysis indicated that size and treatment time of SiNPs were the associated factors in vitro genotoxicity. The size of SiNPs, <21 nm, induced more DNA damage than larger sized SiNPs. It could induce MN formation when the treatment time of SiNPs was <12 h, and even more DNA damage when the exposure time over 12 h. SiNPs can induce genotoxicity both in vivo and in vitro. Comet assay may be more sensitive to detect in vitro genotoxicity, and MN frequency may be more suitable to detect in vivo genotoxicity. [ABSTRACT FROM AUTHOR]