Age-related degradation of tectorial membrane dynamics with loss of CEACAM16.

Studies of genetic disorders of sensorineural hearing loss have been instrumental in delineating mechanisms that underlie the remarkable sensitivity and selectivity that are hallmarks of mammalian hearing. For example, genetic modifications of TECTA and TECTB, which are principal proteins that comprise the tectorial membrane (TM), have been shown to alter auditory thresholds and frequency tuning in ways that can be understood in terms of changes in the mechanical properties of the TM. Here, we investigate effects of genetic modification targeting CEACAM16, a third important TM protein. Loss of CEACAM16 has been recently shown to lead to progressive reductions in sensitivity. Whereas age-related hearing losses have previously been linked to changes in sensory receptor cells, the role of the TM in progressive hearing loss is largely unknown. Here, we show that TM stiffness and viscosity are significantly reduced in adult mice that lack functional CEACAM16 relative to age-matched wild-type controls. By contrast, these same mechanical properties of TMs from juvenile mice that lack functional CEACAM16 are more similar to those of wild-type mice. Thus, changes in hearing phenotype align with changes in TM material properties and can be understood in terms of the same TM wave properties that were previously used to characterize modifications of TECTA and TECTB. These results demonstrate that CEACAM16 is essential for maintaining TM mechanical and wave properties, which in turn are necessary for sustaining the remarkable sensitivity and selectivity of mammalian hearing with increasing age.

A fluorescent photoimmunoconjugate for imaging of cholesteatoma.

Cholesteatoma is a potentially serious complication of chronic ear infections and requires surgical intervention for definitive management. Long-term complications include a frequent need for repeat surgical intervention for disease recurrence, and techniques to improve efficacy of single-stage surgery are an important area of continued research. This study investigates a novel application of the photosensitizer immune conjugate (PIC) cetuximab-benzoporphyrin derivative (Cet-BPD) for in vitro localization of human cholesteatoma tissue, coupled with an in vivo safety study for middle ear application of Cet-BPD in a murine model. In fresh human cholesteatoma tissues, Cet-BPD demonstrates selective localization to the hyperplastic squamous cell tissue associated with cholesteatoma, without localizing to other tissues such as middle ear mucosa. Applied to the murine middle ear, Cet-BPD does not demonstrate any deleterious effect on murine hearing when assessed by any of auditory brainstem response (ABR) thresholds, distortion product otoacoustic emission thresholds, or ABR wave I amplitudes. These findings demonstrate the technical promise and encouraging safety profile for the use of PICs for intraoperative localization and treatment of cholesteatoma.

State of Sweat: Emerging Wearable Systems for Real-Time, Noninvasive Sweat Sensing and Analytics.

Skin-interfaced wearable systems with integrated colorimetric assays, microfluidic channels, and electrochemical sensors offer powerful capabilities for noninvasive, real-time sweat analysis. This Perspective details recent progress in the development and translation of novel wearable sensors for personalized assessment of sweat dynamics and biomarkers, with precise sampling and real-time analysis. Sensor accuracy, system ruggedness, and large-scale deployment in remote environments represent key opportunity areas, enabling broad deployment in the context of field studies, clinical trials, and recent commercialization. On-body measurements in these contexts show good agreement compared to conventional laboratory-based sweat analysis approaches. These device demonstrations highlight the utility of biochemical sensing platforms for personalized assessment of performance, wellness, and health across a broad range of applications.

Conductive Hearing Loss in the Hyp Mouse Model of X-Linked Hypophosphatemia Is Accompanied by Hypomineralization of the Auditory Ossicles.

X-linked hypophosphatemia (XLH) is a hereditary musculoskeletal disorder caused by loss-of-function mutations in the PHEX gene. In XLH, increased circulating fibroblast growth factor 23 (FGF23) levels cause renal phosphate wasting and low concentrations of 1,25-dihydroxyvitamin D, leading to an early clinical manifestation of rickets. Importantly, hearing loss is commonly observed in XLH patients. We present here data from two XLH patients with marked conductive hearing loss. To decipher the underlying pathophysiology of hearing loss in XLH, we utilized the Hyp mouse model of XLH and measured auditory brain stem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) to functionally assess hearing. As evidenced by the increased ABR/DPOAE threshold shifts in the mid-frequency range, these measurements indicated a predominantly conductive hearing loss in Hyp mice compared to wild-type (WT) mice. Therefore, we carried out an in-depth histomorphometric and scanning electron microscopic analysis of the auditory ossicles. Quantitative backscattered electron imaging (qBEI) indicated a severe hypomineralization of the ossicles in Hyp mice, evidenced by lower calcium content (CaMean) and higher void volume (ie, porosity) compared to WT mice. Histologically, voids correlated with unmineralized bone (ie, osteoid), and the osteoid volume per bone volume (OV/BV) was markedly higher in Hyp mice than WT mice. The density of osteocyte lacunae was lower in Hyp mice than in WT mice, whereas osteocyte lacunae were enlarged. Taken together, our findings highlight the importance of ossicular mineralization for hearing conduction and point toward the potential benefit of improving mineralization to prevent hearing loss in XLH. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).