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The comet assay in nanotoxicology research.Nanoscale particles can have impressive and useful characteristics, but the same properties may be problematic for human health. From this perspective it is critical to assess the ability of nanoparticles to cause DNA damage. This review focuses on the use of the comet assay in nanotoxicology research. In the alkaline version of the assay, DNA strand breaks and alkali-labile sites are detected and oxidatively damaged DNA can be analyzed using the enzyme formamidopyrimidine glycosylase. The article reviews studies that have used the comet assay to investigate the toxicity of manufactured nanoparticles. It is shown that at least 46 cellular in vitro studies and several in vivo studies have used the comet assay and that the majority of the nanoparticles tested cause DNA strand breaks or oxidative DNA lesions. This is not surprising considering the sensitivity of the method and the reactivity of many nanomaterials. Interactions between the particles and the assay cannot be totally excluded and need further consideration. It is concluded that studies including several particle types, to enable the assessment of their relative potency, are valuable as are studies focusing both on comet assay end points and mutagenicity. Finally, the article discusses the potential future use of the comet assay in human biomonitoring studies, which could provide valuable information for hazard identification of nanoparticles.
LC-QTOF/MS metabolomic profiles in human plasma after a 5-week high dietary fiber intake.The objective was to investigate the alterations of plasma metabolome profiles to identify exposure and effect markers of dietary fiber intake. Subjects (n = 25) aged 58.6 (1.1) years (mean and SD) with a body mass index of 26.6 (0.5) kg/m(2) were given a high fiber (HF) and a low fiber (LF) diet, in a 5-week randomized controlled crossover intervention. The HF diet consisted of oat bran, rye bran, and sugar beet fiber incorporated into test food products, whereas the LF diet was made of equivalent food products to the HF diet, but without adding fibers. Blood plasma samples were collected at the start and end of each intervention period and analyzed by LC-QTOF/MS. In total, 6 features in positive mode and 14 features in negative mode were significantly different between the HF and the LF diet (p < 0.01, q < 0.05). Two markers, 2,6-dihydroxybenzoic acid and 2-aminophenol sulfate, were increased after HF diet, along with a tentatively identified saponin derived from oat avenacosides. The untargeted metabolomics approach enabled the identification of two new markers of dietary fiber intake in human plasma. Further studies will be needed to verify if these markers could serve as compliance markers of fiber intake.