Objectives: Few studies examined the association between deterioration of masticatory ability assessed by objective marker and physical function. Therefore, we examined the association between salivary flow rate which is one of the objective and surrogate marker of masticatory ability and lower Timed Up & Go (TUG) performance which is one of major measurement of physical function among aging Japanese. Methods: This cross-sectional study enrolled 464 Japanese aged 60e84 years old. Participants chewed tasteless and odorless gum for 5 min, calculated stimulated salivary flow rate (g/min) during all chews.The 3 m TUG was conducted, and 75th percentile value (6.8 s for men and 7.0 s for women) or higher was defined as lower TUG performance. Logistic regression analysis was used to examine the association between stimulated salivary flow rate and lower TUG performance. Results: We found that the stimulated salivary flow rate tended to be negatively associated with the TUG time. We also observed significant negative association between stimulated salivary flow rate and lower TUG performance; the multivariable-adjusted OR (95% confidence interval, CIs) of lower TUG performance for the highest quartile of stimulated salivary flow rate compared with the lowest quartile was0.34 (0.16e0.69, P for trend ¼ 0.02). Further adjusting for BMI, the association was attenuated but remaind significant; the OR (95% CIs) in highest quartile was 0.37 (0.18e0.76, P for trend ¼ 0.04). Conclusions Higher stimulated salivary flow, which means well masticatory ability, was inversely associated with lower TUG performance in the aging Japanese population.

OBJECTIVETeeth can serve as records of environmental exposure to heavy metals during their formation. We applied a new technology - synchrotron radiation microbeams (SRXRF) - for analysis of heavy metals in human permanent teeth in modern and historical samples.

METHODSEach tooth was cut in half. A longitudinal section 200 mum in thickness was subjected to the determination of the heavy metal content by SRXRF or conventional analytical methods (ICP-MS analysis or reduction-aeration atomic absorption spectrometry). The relative concentrations of Pb, Hg, Cu and Zn measured by SRXRF were translated in concentrations (in g of heavy metal/g of enamel) using calibration curves by the two analytical methods.

RESULTSConcentrations in teeth in the modern females (n = 5) were 1.2 +/- 0.5 mug/g (n = 5) for Pb; 1.7 +/- 0.2 ng/g for Hg; 0.9 +/- 1.1 mug/g for Cu; 150 +/- 24.6 mug/g for Zn. The levels of Pb were highest in the teeth samples obtained from the humans of the Edo era (1603-1868 AD: ) (0.5-4.0 mug/g, n = 4). No trend was observed in this study in the Hg content in teeth during 3,000 years. The concentrations of Cu were highest in teeth of two medieval craftsmen (57.0 and 220 mug/g). The levels of Zn were higher in modern subjects (P < 0.05) than those in the Jomon (~1000 BC: ) to Edo periods [113.2 +/- 27.4 (mug/g, n = 11)]. Reconstruction of developmental exposure history to lead in a famous court painter of the Edo period (18th century) revealed high levels of Pb (7.1-22.0 mug/g) in his childhood.

CONCLUSIONSSRXRF is useful a method for reconstructing human exposures in very long trends.