The Relation of Sound Level Tolerance to Tinnitus Ears in Human.

BACKGROUND: The aim of this study was to evaluate the relationship between sound level tolerance and tinnitus in humans. METHODS: We compared the loudness discomfort levels at 500 and 3000 Hz pure tones in 33 subjects with bilateral tinnitus and 33 subjects with unilateral tinnitus with normal and symmetric hearing thresholds and those of age- and sex-matched control subjects. RESULTS: Both the tinnitus ears (108.18 ± 10.22 dB HL and 103.03 ± 11.04 dB HL) and non-tinnitus ears (108.94 ± 12.61 dB HL and 104.24 ± 11.60 dB HL) in the unilateral tinnitus subjects showed significantly lower loudness discomfort levels at 500 and 3000 Hz than the control ears (115.91 ± 6.78 dB HL and 111.52 ± 8.88 dB HL, P < .008; α=0.05/6=0.008), whereas there was no difference in the loudness discomfort levels of the tinnitus ears of the bilateral tinnitus subjects (111.52 ± 10.42 dB HL or 106.36 ± 11.34 dB HL) and the control ears. CONCLUSION: These results support the hypothesis that the reduced loudness discomfort levels in tinnitus subjects with normal and symmetric hearing thresholds are associated with a hidden injury to the cochlea that induces the development of tinnitus, especially on one side. Whether tinnitus is perceived unilaterally or bilaterally depends on the status of the auditory system, which may be reflected in the sound level tolerance and loudness discomfort levels.

A rapid, efficient, and facile solution for dental hypersensitivity: The tannin-iron complex.

Dental hypersensitivity due to exposure of dentinal tubules under the enamel layer to saliva is a very popular and highly elusive technology priority in dentistry. Blocking water flow within exposed dentinal tubules is a key principle for curing dental hypersensitivity. Some salts used in "at home" solutions remineralize the tubules inside by concentrating saliva ingredients. An "in-office" option of applying dense resin sealants on the tubule entrance has only localized effects on well-defined sore spots. We report a self-assembled film that was formed by facile, rapid (4 min), and efficient (approximately 0.5 g/L concentration) dip-coating of teeth in an aqueous solution containing a tannic acid-iron(III) complex. It quickly and effectively occluded the dentinal tubules of human teeth. It withstood intense tooth brushing and induced hydroxyapatite remineralisation within the dentinal tubules. This strategy holds great promise for future applications as an effective and user-friendly desensitizer for managing dental hypersensitivity.

Cellular mechanisms of mutations in Kv7.1: auditory functions in Jervell and Lange-Nielsen syndrome vs. Romano-Ward syndrome.

As a result of cell-specific functions of voltage-activated K(+) channels, such as Kv7.1, mutations in this channel produce profound cardiac and auditory defects. At the same time, the massive diversity of K(+) channels allows for compensatory substitution of mutant channels by other functional channels of their type to minimize defective phenotypes. Kv7.1 represents a clear example of such functional dichotomy. While several point mutations in the channel result in a cardio-auditory syndrome called Jervell and Lange-Nielsen syndrome (JLNS), about 100-fold mutations result in long QT syndrome (LQTS) denoted as Romano-Ward syndrome (RWS), which has an intact auditory phenotype. To determine whether the cellular mechanisms for the diverse phenotypic outcome of Kv7.1 mutations, are dependent on the tissue-specific function of the channel and/or specialized functions of the channel, we made series of point mutations in hKv7.1 ascribed to JLNS and RWS. For JLNS mutations, all except W248F yielded non-functional channels when expressed alone. Although W248F at the end of the S4 domain yielded a functional current, it underwent marked inactivation at positive voltages, rendering the channel non-functional. We demonstrate that by definition, none of the JLNS mutants operated in a dominant negative (DN) fashion. Instead, the JLNS mutants have impaired membrane trafficking, trapped in the endoplasmic reticulum (ER) and Cis-Golgi. The RWS mutants exhibited varied functional phenotypes. However, they can be summed up as exhibiting DN effects. Phenotypic differences between JLNS and RWS may stem from tissue-specific functional requirements of cardiac vs. inner ear non-sensory cells.