The prevalence of hearing loss in South Korea: data from a population-based study.

OBJECTIVES/HYPOTHESIS: In the present study, we aimed to determine the prevalence of hearing loss in the South Korean population and to understand the correlation between aging, sex, and hearing loss prevalence through the analysis of data collected from the Korea National Health and Nutrition Examination Survey (KNHANES). STUDY DESIGN: Cross-sectional epidemiological study. METHODS: The KNHANES is an ongoing population study that started in 1998. Examinations to detect diseases of the ear, nose, and throat, including audiological testing and otologic examinations, have been conducted since 2010. We included a total of 18,650 participants in the KNHANES, from 2010 to 2012, in the present study. Pure-tone audiometric testing was conducted in participants aged ≥ 12 years. The frequencies tested were 0.5, 1, 2, 3, 4, and 6 kHz. RESULTS: The prevalence of hearing loss in speech-relevant frequencies in the South Korean population was 9.31% for unilateral hearing loss and 13.42% for bilateral hearing loss. The overall hearing loss (unilateral or bilateral) was 22.73%. Male and older participants were more often affected by hearing loss than female and younger participants. High-frequency hearing loss appeared earlier than hearing loss at speech-relevant frequencies, and unilateral hearing loss showed a weaker correlation with aging than bilateral hearing loss. CONCLUSION: The prevalence of hearing loss in South Korea was higher in men and older participants according to the data collected from the KNHANES. The patterns of hearing loss differed between hearing loss at speech-relevant frequencies and at high frequencies.

Dental enamel structure is altered by expression of dominant negative RhoA in ameloblasts.

Using in vitrotooth germ cultures and analysis by confocal microscopy, ameloblasts treated with sodium fluoride were found to have elevated amounts of filamentous actin. Because this response is reduced by inhibitors of the Rho/ROCK signaling pathway, we generated mice that express dominant negative RhoA (RhoA(DN)) in ameloblasts for in vivo analysis. Expression of the EGFP-RhoA(DN) fusion protein was evaluated by RT-PCR and immunohistochemistry, and teeth were analyzed by scanning electron microscopy. The 3 strains expressed at either low (TgEGFP-RhoA(DN)-8), intermediate (TgEGFP-RhoA(DN)-2), or high (TgEGFP-RhoA(DN)-13) levels, and the molar teeth from the 3 strains had enamel hypoplasia and surface defects. We conclude that RhoA(DN) expressed in ameloblasts interferes with normal enamel development through the pathway that is induced by sodium fluoride.