30-year trends of hip and vertebral fracture incidence in Japan: a systematic review and meta-analysis.

INTRODUCTION: A previous review study showed the trends of declining age- and sex-adjusted incidence of hip fractures in almost all the countries, except Austria and Japan, in the most recent of the periods studied. However, the expansion of devices for diagnosis and drugs for fracture prevention in Japan was roughly the same as in the other countries. This study aimed to conduct a comprehensive systematic review and meta-analyses of incidence rates (IRs) of osteoporotic fractures reported over 30-years in multiple communities in Japan and to evaluate secular trends. MATERIALS AND METHODS: We searched MEDLINE for observational studies reporting IRs of osteoporotic fractures in the general population. Additional studies were identified by hand searches of reference lists of published studies. Two reviewers and 1 expert independently assessed study eligibility. Pooled analyses of IRs were conducted by a random-effect model. Data from 3 periods (1985-1999, 2000-2009, and from 2010) were compared. RESULTS: Of 47 eligible studies, 21 with IRs or information enabling recalculation of IRs in the population aged 50 years and older were included. IRs of hip fractures per 100,000 person-years significantly increased over time in men: 1985-1999, 0.79 (95% CI 0.71-0.87); 2000-2009, 1.18 (95% CI 1.09-1.28); and 2010 onwards, 1.31 (95% CI 1.17-1.45). They also significantly increased in women: 2.23 (95% CI 1.89-2.58); 3.99 (95% CI 3.70-4.28); and 4.39 (95% CI 4.00-4.78), respectively. CONCLUSION: IRs of hip fractures continuously increased in the past 30-years in men and women despite improved the diagnosis, treatment, and care. Such data from Japan, a leading aging society, provide important information for other countries.

Synthesis and characterization of nanoemulsion-mediated core crosslinked nanoparticles, and in vivo pharmacokinetics depending on the structural characteristics.

For designing nanoparticles as drug carriers, a covalently crosslinked structure is necessary for the structural stability in vivo. In this study, we prepared core crosslinked nanoparticles through the formation of nanoemulsions stabilized by poly(ethylene glycol) (PEG)-bearing surfactants. The structural characteristics of these particles were carefully evaluated using small-angle scattering techniques including dynamic, static, X-ray, and neutron scattering. The particles demonstrated high stability even in vivo, with the suppression of premature drug release owing to the crosslinked structure. Interestingly, the ability to retain encapsulated molecules was dependent on the molecular weight of PEG in vivo, presumably due to the difference in the crowding density of PEG chains at the outermost surface. This suggests that conferring structural stability via a core crosslinked structure is surely important, but we also need to consider controlling the crowding density of the hydrophilic polymer chains in the particle shell when designing drug carriers.