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Titanium dioxide (TiO2) is a common food additive used to enhance the white color, brightness, and sometimes flavor of a variety of food products. In this study 7 food grade TiO2 materials (E171), 24 food products, and 3 personal care products were investigated for their TiO2 content and the number-based size distribution of TiO2 particles present in these products. Three principally different methods have been used to determine the number-based size distribution of TiO2 particles: electron microscopy, asymmetric flow field-flow fractionation combined with inductively coupled mass spectrometry, and single-particle inductively coupled mass spectrometry. The results show that all E171 materials have similar size distributions with primary particle sizes in the range of 60-300 nm. Depending on the analytical method used, 10-15% of the particles in these materials had sizes below 100 nm. In 24 of the 27 foods and personal care products detectable amounts of titanium were found ranging from 0.02 to 9.0 mg TiO2/g product. The number-based size distributions for TiO2 particles in the food and personal care products showed that 5-10% of the particles in these products had sizes below 100 nm, comparable to that found in the E171 materials. Comparable size distributions were found using the three principally different analytical methods. Although the applied methods are considered state of the art, they showed practical size limits for TiO2 particles in the range of 20-50 nm, which may introduce a significant bias in the size distribution because particles <20 nm are excluded. This shows the inability of current state of the art methods to support the European Union recommendation for the definition of nanomaterials.

Tea remains the most consumed drink in the world after water, well ahead of coffee, beer, wine and carbonated soft drinks. An accumulated number of population studies suggests that consumption of green and black tea beverages may bring positive health effects (1). One hypothesis explaining such effects is that the high levels of flavonoids in tea can protect cells and tissues from oxidative damage by scavenging oxygen-free radicals. Chemically, the flavonoids found in green and black tea are very effective radical scavengers. The tea flavonoids may therefore be active as antioxidants in the digestive tract or in other tissues after uptake. A substantial number of human intervention studies with green and black tea demonstrates a significant increase in plasma antioxidant capacity in humans approximately 1 h after consumption of moderate amounts of tea (1-6 cups/d). There are initial indications that the enhanced blood antioxidant potential leads to reduced oxidative damage to macromolecules such as DNA and lipids. However, the measurement of oxidative damage through biomarkers needs to be further established. In conclusion, tea flavonoids are potent antioxidants that are absorbed from the gut after consumption. Tea consumption consistently leads to a significant increase in the antioxidant capacity of the blood. Beneficial effects of increased antioxidant capacity in the body may be the reduction of oxidative damage to important biomolecules. The scientific support is strongest for the protection of DNA from oxidative damage after black or green tea consumption. However, the quality of the studies now available is insufficient to draw firm conclusions. Therefore, further evidence from human intervention studies is required.

In vertebrates, the formation of raft lipid microdomains plays an important part in both polarized protein sorting and signal transduction. To establish a system in which raft-dependent processes could be studied genetically, we have analyzed the protein and lipid composition of these microdomains in Drosophila melanogaster. Using mass spectrometry, we identified the phospholipids, sphingolipids, and sterols present in Drosophila membranes. Despite chemical differences between Drosophila and mammalian lipids, their structure suggests that the biophysical properties that allow raft formation have been preserved. Consistent with this, we have identified a detergent-insoluble fraction of Drosophila membranes that, like mammalian rafts, is rich in sterol, sphingolipids, and glycosylphosphatidylinositol-linked proteins. We show that the sterol-linked Hedgehog Nterminal fragment associates specifically with this detergent-insoluble membrane fraction. Our findings demonstrate that raft formation is preserved across widely separated phyla in organisms with different lipid structures. They further suggest sterol modification as a novel mechanism for targeting proteins to raft membranes and raise the possibility that signaling and polarized intracellular transport of Hedgehog are based on raft association.Recent evidence suggests that lipids in mammalian membranes are not uniformly miscible, but that lateral separation of specific lipid species leads to the formation of specialized phase domains called rafts. In mammals, the association of membrane proteins with raft lipid microdomains has emerged as an important regulator of polarized intracellular sorting and signal transduction (1, 2).Raft formation is based on the tendency of cholesterol to organize the bilayer into cholesterol-rich liquid ordered and cholesterol-poor liquid disordered domains (3), a process that is enhanced by the preferential interaction of cholesterol with sphingolipids and the fact that sphingolipids have higher melting temperatures than phospholipids (Ref. 4; reviewed in Ref. 5). Rafts form when the sphingolipid/cholesterol-rich phase separates from the phospholipid-rich phase that constitutes the rest of the membrane. In model membranes, the formation of the liquid ordered phase correlates with the acquisition of insolubility in the nonionic detergent Triton X-100 (6). Insolubility in Triton X-100 or in Triton X-114, a related detergent, has been used as a criterion for isolation of rafts from cellular membranes (7,8).We decided to establish a system to study rafts in a genetic model organism with well characterized development: Drosophila melanogaster. Genetics would provide a powerful tool with which to identify molecules involved in raft formation, trafficking, and function. Furthermore, since raft formation is thought to play important roles in cell polarization and signal transduction, examining their functions in Drosophila may provide insights into the control of important developmental processes.We began by asking whether Drosophila mem...