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This study examines absolute hair cell numbers in the cristae of C57BL/6J mice and CBA/CaJ mice from weaning to adulthood as well as the dose required for 3,3'-iminodiproprionitrile (IDPN)-injury of the cristae in C57BL/6J mice and CBA/CaJ mice, the two mouse strains most commonly used by inner ear researchers. In cristae of CBA/CaJ and C57BL/6J mice, no loss of hair cells was observed up to 24 weeks. In both strains, dose-dependent loss of hair cells was observed 7 days after IDPN treatment of 2-month-old mice (IC = 16.1 mmol/kg in C57BL/6J mice vs. 25.21 mmol/kg in CBA/CaJ mice). Four-month-old C57BL/6J mice exposed to IDPN developed dose-dependent vestibular dysfunction as indicated by increased activity and circling behavior in open field tests and by failure to swim 7 days after treatment. IDPN-hair cell injury in C57BL/6J mice and CBA/CaJ mice represents a fast and predictable experimental model for the study of vestibular degeneration and a platform for the testing of vestibular therapies.

Objectives Moving into a retirement community may be precipitated by or bring about changes in health status. We hypothesized that moving into a retirement community would be associated with a decline in self-rated health (SRH), but that health-related factors would mitigate this association. Methods We analyzed data from 58,272 participants in Cohort 3 of the Medicare Health Outcome Survey. Individuals answered questions regarding living status in 2000 and 2002. Those who moved into a retirement community were compared with those who did not. The primary outcome was change in SRH. We created adjusted and unadjusted models. Results 2,520 (4.4%) individuals moved into retirement communities between 2000 and 2002. There were no substantial differences in the mean change in SRH between those who moved and those who did not. In adjusted and unadjusted models, moving was not significantly associated with changes in SRH. In an analysis stratified by SRH, only those with the best SRH had a significant decline in SRH during the move. Discussion SRH mainly remained stable for most people regardless of moving into a retirement community. These findings argue against environmental context being a main determinant of self-perceived health status among older adults.