Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in (16)O relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid.

An enrichment of oxygen-16 of about 8% relative to the Earth has been found in a chondrule from the Acfer 214 carbonaceous chondrite. In contrast, isotopic abundances of major cations, Mg and Si, are similar to those of the Earth. These suggest that oxygen isotopic heterogeneity in the early solar system was much larger ever thought and assist mass-independent-isotopic fractionation for the origin. Because the chondrule has solar abundance for refractory and normal lithophile elements, we propose that silicate dusts in the early solar system were initially enriched in 16 O corresponding to the 16 O-rich reservoir.

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Liver transplantation can halt the progression of peripheral neuropathy in FAP patients.

The purpose of this study is to compare the state of teeth in young adults who had consumed fluoridated water from birth to 5-8 yr of age with the subjects who had non-fluoridated water. The sample consisted of 117 18-22-yr-old female nursing school students. The data obtained in dental examinations were sorted according to their place of residence, and then divided into groups depending on whether their place of residence had been supplied with fluoridated water or not. The fluoride concentration in the water had been 0.7-1.0 ppm in the six water supply systems which were under the control of the US military base. In the subjects who had fluoridated water, the following differences were found when compared to the control subjects: missing teeth and highly progressed caries occurred less frequently; significantly lower caries prevalence was present on free smooth and approximal surfaces; the overall DMFT differences in favor of the fluoridated subjects were small and non-significant.