Noise-induced trauma produces a temporal pattern of change in blood levels of the outer hair cell biomarker prestin

Publication date: Available online 30 November 2018

Source: Hearing Research

Author(s): Kourosh Parham, Maheep Sohal, Mathieu Petremann, Charlotte Romanet, Audrey Broussy, Christophe Tran Van Ba, Jonas Dyhrfjeld-Johnsen

Abstract

Biomarkers in easy-to-access body fluid compartments, such as blood, are commonly used to assess health of various organ systems in clinical medicine. At present, no such biomarkers are available to inform on the health of the inner ear. Previously, we proposed the outer-hair-cell-specific protein prestin, as a possible biomarker and provided proof of concept in noise- and cisplatin-induced hearing loss. Our ototoxicity data suggest that circulatory prestin changes after inner ear injury are not static and that there is a temporal pattern of change that needs to be further characterized before practical information can be extracted. To achieve this goal, we set out to 1) describe the time course of change in prestin after intense noise exposure, and 2) determine if the temporal patterns and prestin levels are sensitive to severity of injury. After assessing auditory brainstem thresholds and distortion product otoacoustic emission levels, rats were exposed to intense octave band noise for 2 hours at either 110 or 120 dB SPL. Auditory function was re-assessed 1 and 14 days later. Blood samples were collected at baseline, 4, 24, 48, 72 hrs and 7 and 14 days post exposure and prestin concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Functional measures showed temporary hearing loss 1 day after exposure in the 110 dB SPL group, but permanent loss through Day 14 in the 120 dB SPL group. Prestin levels temporarily increased 5% at 4 hrs after 120 dB SPL exposure, but not in the 110 dB SPL group. There was a gradual decline in prestin levels in both groups thereafter, with prestin being below baseline on Day 14 by 5% in the 110 dB group (NS) and more than 10% in the 120 dB SPL group (p = 0.043). These results suggest that there is a temporal pattern of change in serum prestin level after noise-induced hearing loss that is related to severity of hearing loss. Circulatory levels of prestin may be able to act as surrogate biomarker for hearing loss involving OHC loss.

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Noise-induced trauma produces a temporal pattern of change in blood levels of the outer hair cell biomarker prestin

Publication date: Available online 30 November 2018

Source: Hearing Research

Author(s): Kourosh Parham, Maheep Sohal, Mathieu Petremann, Charlotte Romanet, Audrey Broussy, Christophe Tran Van Ba, Jonas Dyhrfjeld-Johnsen

Abstract

Biomarkers in easy-to-access body fluid compartments, such as blood, are commonly used to assess health of various organ systems in clinical medicine. At present, no such biomarkers are available to inform on the health of the inner ear. Previously, we proposed the outer-hair-cell-specific protein prestin, as a possible biomarker and provided proof of concept in noise- and cisplatin-induced hearing loss. Our ototoxicity data suggest that circulatory prestin changes after inner ear injury are not static and that there is a temporal pattern of change that needs to be further characterized before practical information can be extracted. To achieve this goal, we set out to 1) describe the time course of change in prestin after intense noise exposure, and 2) determine if the temporal patterns and prestin levels are sensitive to severity of injury. After assessing auditory brainstem thresholds and distortion product otoacoustic emission levels, rats were exposed to intense octave band noise for 2 hours at either 110 or 120 dB SPL. Auditory function was re-assessed 1 and 14 days later. Blood samples were collected at baseline, 4, 24, 48, 72 hrs and 7 and 14 days post exposure and prestin concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Functional measures showed temporary hearing loss 1 day after exposure in the 110 dB SPL group, but permanent loss through Day 14 in the 120 dB SPL group. Prestin levels temporarily increased 5% at 4 hrs after 120 dB SPL exposure, but not in the 110 dB SPL group. There was a gradual decline in prestin levels in both groups thereafter, with prestin being below baseline on Day 14 by 5% in the 110 dB group (NS) and more than 10% in the 120 dB SPL group (p = 0.043). These results suggest that there is a temporal pattern of change in serum prestin level after noise-induced hearing loss that is related to severity of hearing loss. Circulatory levels of prestin may be able to act as surrogate biomarker for hearing loss involving OHC loss.

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Prediction of power output at different running velocities through the two-point method with the Stryd™ power meter

Publication date: Available online 30 November 2018

Source: Gait & Posture

Author(s): Felipe García-Pinillos, Pedro Á. Latorre-Román, Luis E. Roche-Seruendo, Amador García-Ramos

Abstract

Background

The force- and power-velocity (F-V and P-V, respectively) relationships have been extensively studied in recent years. However, its use and application in endurance running events is limited.

Research question

This study aimed to determine if the P-V relationship in endurance runners fits a linear model when running at submaximal velocities, as well as to examine the feasibility of the “two-point method” for estimating power values at different running velocities.

Methods

Eighteen endurance runners performed, on a motorized treadmill, an incremental running protocol to exhaustion. Power output was obtained at each stage with the Stryd™ power meter. The P-V relationship was determined from a multiple-point method (10, 12, 14, and 17 km·h^-1) as well as from three two-point methods based on proximal (10 and 12 km·h^-1), intermediate (10 and 14 km·h^-1) and distal (10 and 17 km·h^-1) velocities.

Results

The P-V relationship was highly linear ( r = 0.999). The ANOVAs revealed significant, although generally trivial (effect size < 0.20), differences between measured and estimated power values at all the velocities tested. Very high correlations ( r = 0.92) were observed between measured and estimated power values from the 4 methods, while only the multiple-point method ( r² = 0.091) and two-point method distal ( r² = 0.092) did not show heteroscedasticity of the error.

Significance

The two-point method based on distant velocities (i.e., 10 and 17 km·h^-1) is able to provide power output with the same accuracy than the multiple-point method. Therefore, since the two-point method is quicker and less prone to fatigue, we recommend the assessment of power output under only two distant velocities to obtain an accurate estimation of power under a wide range of submaximal running velocities.

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Researchers Identify Key Gene Associated with Age-Related Hearing Loss

​Researchers have discovered the gene that acts as a key regulator for outer hair cell, the loss of which is the major cause of age-related hearing loss. (Nature. 2018 Nov;563(7733):696-700.) They identified Ikzf2 as an essential transcription factor in mice that is required for outer hair cell (OHC) functional maturation and hearing. Ikzf2 encodes the protein helios, found in postnatal mouse OHCs and when OHCs begins to mature, establishing that helios is a key component in OHC specification. The researchers also found that a mutation in Ikzf2 caused early-onset sensorineural hearing loss and significantly reduced electromotility, the ability of OHCs to amplify low-level sounds and function properly. Findings from this study will help researchers better understand this unique type of cell needed for hearing and potentially develop treatments for age-related hearing loss.

Published: 11/30/2018 11:47:00 AM

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Prediction of power output at different running velocities through the two-point method with the Stryd™ power meter

Publication date: Available online 30 November 2018

Source: Gait & Posture

Author(s): Felipe García-Pinillos, Pedro Á. Latorre-Román, Luis E. Roche-Seruendo, Amador García-Ramos

Abstract

Background

The force- and power-velocity (F-V and P-V, respectively) relationships have been extensively studied in recent years. However, its use and application in endurance running events is limited.

Research question

This study aimed to determine if the P-V relationship in endurance runners fits a linear model when running at submaximal velocities, as well as to examine the feasibility of the “two-point method” for estimating power values at different running velocities.

Methods

Eighteen endurance runners performed, on a motorized treadmill, an incremental running protocol to exhaustion. Power output was obtained at each stage with the Stryd™ power meter. The P-V relationship was determined from a multiple-point method (10, 12, 14, and 17 km·h^-1) as well as from three two-point methods based on proximal (10 and 12 km·h^-1), intermediate (10 and 14 km·h^-1) and distal (10 and 17 km·h^-1) velocities.

Results

The P-V relationship was highly linear ( r = 0.999). The ANOVAs revealed significant, although generally trivial (effect size < 0.20), differences between measured and estimated power values at all the velocities tested. Very high correlations ( r = 0.92) were observed between measured and estimated power values from the 4 methods, while only the multiple-point method ( r² = 0.091) and two-point method distal ( r² = 0.092) did not show heteroscedasticity of the error.

Significance

The two-point method based on distant velocities (i.e., 10 and 17 km·h^-1) is able to provide power output with the same accuracy than the multiple-point method. Therefore, since the two-point method is quicker and less prone to fatigue, we recommend the assessment of power output under only two distant velocities to obtain an accurate estimation of power under a wide range of submaximal running velocities.

from #Audiology via ola Kala on Inoreader https://ift.tt/2FSvVAN
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Researchers Identify Key Gene Associated with Age-Related Hearing Loss

​Researchers have discovered the gene that acts as a key regulator for outer hair cell, the loss of which is the major cause of age-related hearing loss. (Nature. 2018 Nov;563(7733):696-700.) They identified Ikzf2 as an essential transcription factor in mice that is required for outer hair cell (OHC) functional maturation and hearing. Ikzf2 encodes the protein helios, found in postnatal mouse OHCs and when OHCs begins to mature, establishing that helios is a key component in OHC specification. The researchers also found that a mutation in Ikzf2 caused early-onset sensorineural hearing loss and significantly reduced electromotility, the ability of OHCs to amplify low-level sounds and function properly. Findings from this study will help researchers better understand this unique type of cell needed for hearing and potentially develop treatments for age-related hearing loss.

Published: 11/30/2018 11:47:00 AM

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