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This report describes tests of a standard practice for quantifying the performance of implantable middle ear hearing devices (also known as implantable hearing aids). The standard and these tests were initiated by the Food and Drug Administration of the United States Government. The tests involved measurements on two hearing devices, one commercially available and the other home built, that were implanted into ears removed from human cadavers. The tests were conducted to investigate the utility of the practice and its outcome measures: the equivalent ear canal sound pressure transfer function that relates electrically driven middle ear velocities to the equivalent sound pressure needed to produce those velocities, and the maximum effective ear canal sound pressure. The practice calls for measurements in cadaveric ears in order to account for the varied anatomy and function of different human middle ears.

The multifunctional protein phosphoglucose isomerase, also known as neuroleukin, autocrine motility factor, and differentiation and maturation mediator, has different roles inside and outside the cell. In the cytoplasm, it catalyzes the second step in glycolysis. Outside the cell, it serves as a nerve growth factor and cytokine. We have determined the three-dimensional structure of rabbit muscle phosphoglucose isomerase complexed with the competitive inhibitor D-gluconate 6-phosphate by X-ray crystallography at 2.5 A resolution. The structure shows that the enzyme is a dimer with two alpha/beta-sandwich domains in each subunit. The location of the bound D-gluconate 6-phosphate inhibitor leads to the identification of residues involved in substrate specificity (Ser209, Ser159, Thr214, Thr217, and Thr211). The results of previously published kinetic studies suggest that a lysine and a histidine are involved in the catalytic mechanism. The crystal structure suggests active site residues Lys518 and His388 might be these residues. In addition, the positions of amino acid residues that are substituted in the genetic disease nonspherocytic hemolytic anemia suggest how these substitutions can result in altered catalysis or protein stability.

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Cochlear implants allow individuals with severe-to-profound hearing loss access to sound and spoken language. The number of older adults in the United States who are potential candidates for cochlear implantation is approximately 150,000 and will continue to increase with the aging of the population. Should cochlear implantation (CI) be routinely recommended for these older adults, and do these individuals benefit from CI? We reviewed our 12 year experience with cochlear implantation in adults ≥60 years (n = 445) at Johns Hopkins to investigate the impact of CI on speech understanding and to identify factors associated with speech performance. Complete data on speech outcomes at baseline and 1 year post-CI were available for 83 individuals. Our results demonstrate that cochlear implantation in adults ≥60 years consistently improved speech understanding scores with a mean increase of 60. 0% (S. D. 24. 1) on HINT sentences in quiet . The magnitude of the gain in speech scores was negatively associated with age at implantation such that for every increasing year of age at CI the gain in speech scores was 1. 3 percentage points less (95% CI: 0. 6 – 1. 9) after adjusting for age at hearing loss onset. Conversely, individuals with higher pre-CI speech scores (HINT scores between 40–60%) had significantly greater post-CI speech scores by a mean of 10. 0 percentage points (95% CI: 0. 4 – 19. 6) than those with lower pre-CI speech scores (HINT <40%) after adjusting for age at CI and age at hearing loss onset. These results suggest that older adult CI candidates who are younger at implantation and with higher preoperative speech scores obtain the highest speech understanding scores after cochlear implantation with possible implications for current Medicare policy. Finally, we provide an extended discussion of the epidemiology and impact of hearing loss in older adults. Future research of CI in older adults should expand beyond simple speech outcomes to take into account the broad cognitive, social, and physical functioning outcomes that are likely detrimentally impacted by hearing loss and may be mitigated by cochlear implantation.

Epidemiologic studies of hearing loss in adults have demonstrated that the odds of hearing loss are substantially lower in black than in white individuals. The basis of this association is unknown. We hypothesized that skin pigmentation as a marker of melanocytic functioning mediates this observed association and that skin pigmentation is associated with hearing loss independent of race/ethnicity. We analyzed cross-sectional data from 1,258 adults (20-59 years) in the 2003-2004 cycle of the National Health and Nutritional Examination Survey who had assessment of Fitzpatrick skin type and pure-tone audiometric testing. Audiometric thresholds in the worse hearing ear were used to calculate speech-(0.5-4 kHz) and high-frequency (3-8 kHz) pure-tone averages (PTA). Regression models were stratified by Fitzpatrick skin type or race/ethnicity to examine the association of each factor with hearing loss independent of the other. Models were adjusted for potential confounders (demographic, medical, and noise exposure covariates). Among all participants, race/ethnicity was associated with hearing thresholds (black participants with the best hearing followed by Hispanics and then white individuals), but these associations were not significant in analyses stratified by skin color. In contrast, in race-stratified analyses, darker-skinned Hispanics had better hearing than lighterskinned Hispanics by an average of −2.5 dB hearing level (HL; 95% CI, −4.8 to −0.2) and −3.1 dB HL (95% CI, −5.3 to −0.8) for speech and high-frequency PTA, respectively. Associations between skin color and hearing loss were not significant in white and black participants. Our results demonstrate that skin pigmentation is independently associated with hearing loss in Hispanics and suggest that skin pigmentation as a marker of melanocytic functioning may mediate the strong association observed between race/ethnicity and hearing loss.

Superior semicircular canal dehiscence is now a well-established entity in the medical literature. Surgical repair is effective at relieving patients' vestibular symptoms. Lateral semicircular canal dehiscence is usually associated with chronic otitis media. Posterior semicircular canal dehiscence is a rare entity, with similar clinical presentations and treatment options as the other canal dehiscences.