CCDC154 Mutant Caused Abnormal Remodeling of the Otic Capsule and Hearing Loss in Mice

Quantitative Threshold Determination of Auditory Brainstem Responses in Mouse Models

The auditory brainstem response (ABR) is a scalp recording of potentials produced by sound stimulation, and is commonly used as an indicator of auditory function. However, the ABR threshold, which is the lowest audible sound pressure, cannot be objectively determined since it is determined visually using a measurer, and this has been a problem for several decades. Although various algorithms have been developed to objectively determine ABR thresholds, they remain lacking in terms of accuracy, efficiency, and convenience. Accordingly, we proposed an improved algorithm based on the mutual covariance at adjacent sound pressure levels. An ideal ABR waveform with clearly defined waves I-V was created; moreover, using this waveform as a standard template, the experimentally obtained ABR waveform was inspected for disturbances based on mutual covariance. The ABR testing was repeated if the value was below the established cross-covariance reference value. Our proposed method allowed more efficient objective determination of ABR thresholds and a smaller burden on experimental animals.

Bone-turnover biomarkers as potential prognostic factors in sudden sensorineural hearing loss: A prospective cohort study

Objectives

This study aims to explore the relationship between bone-turnover biomarkers and the recovery of SSNHL to provide clues for further improvements in etiological research and predictors.

Methods

The medical history, hearing thresholds, biomarkers of bone-turnover, and related hormones of 117 SSNHL patients were collected prospectively between August 2018 and December 2021. Linear correlation and logistic regression models were applied to examine the association between bone-turnover biomarkers and the prognosis of SSNHL.

Results

Age, the incidence of vertigo, pure tone average of the impaired frequencies (PTAimpairedfre), and the levels of bone turnover [including alkaline phosphatase (ALP), β-carboxy terminal crosslinked telopeptide of type 1 collagen (β-CTX), and N-terminal-midfragment of osteocalcin (N-MID)] were higher in the nonresponders than responders (P < 0.05). Logistic regression showed that the age (OR = 1.035, P = 0.027), time to treatment (OR = 1.157, P = 0.038), PTAimpairedfre (OR = 1.031, P = 0.008), and β-CTX (OR = 1.004, P = 0.001) were independent risk factors for the prognosis of SSNHL. In the women SSNHL subgroup, age, postmenopause percentage, PTAimpairedfre, the activity of ALP, levels of β-CTX, and N-MID were significantly higher in the nonresponders than the responders (P < 0.05). Compared to the men SSNHL subgroup, β-CTX has a higher correlation coefficient and predictive efficiency in the women SSNHL subgroup, and logistic regression showed that β-CTX (OR = 1.004, P = 0.004) was an independent risk factor for the women SSNHL.

Conclusions

Bone-turnover biomarkers are risk factors for poor prognosis in SSNHL, especially β-CTX. The differences were significant in women SSNHL, which may be related to the rapid regression of estrogen after menopause that leads to the occurrence of osteoporosis with a high conversion rate.

Unexpected Motherhood-Triggered Hearing Loss in the Two-Pore Channel (TPC) Mutant Mouse

Calcium signaling is crucial for many physiological processes and can mobilize intracellular calcium stores in response to environmental sensory stimuli. The endolysosomal two-pore channel (TPC), regulated by the second messenger nicotinic acid adenine dinucleotide phosphate (NAADP), is one of the key components in calcium signaling. However, its role in neuronal physiology remains largely unknown. Here, we investigated to what extent the acoustic thresholds differed between the WT mice and the TPC KO mice. We determined the thresholds based on the auditory brainstem responses (ABRs) at five frequencies (between 4 and 32 kHz) and found no threshold difference between the WT and KO in virgin female mice. Surprisingly, in lactating mothers (at P9–P10), the thresholds were higher from 8 to 32 kHz in the TPC KO mice compared to the WT mice. This result indicates that in the TPC KO mice, physiological events occurring during parturition altered the detection of sounds already at the brainstem level, or even earlier.