Grxcr2 is required for stereocilia morphogenesis in the cochlea.

Grxcr2 is required for stereocilia morphogenesis in the cochlea.

PLoS One. 2018;13(8):e0201713

Authors: Avenarius MR, Jung JY, Askew C, Jones SM, Hunker KL, Azaiez H, Rehman AU, Schraders M, Najmabadi H, Kremer H, Smith RJH, Géléoc GSG, Dolan DF, Raphael Y, Kohrman DC

Abstract
Hearing and balance depend upon the precise morphogenesis and mechanosensory function of stereocilia, the specialized structures on the apical surface of sensory hair cells in the inner ear. Previous studies of Grxcr1 mutant mice indicated a critical role for this gene in control of stereocilia dimensions during development. In this study, we analyzed expression of the paralog Grxcr2 in the mouse and evaluated auditory and vestibular function of strains carrying targeted mutations of the gene. Peak expression of Grxcr2 occurs during early postnatal development of the inner ear and GRXCR2 is localized to stereocilia in both the cochlea and in vestibular organs. Homozygous Grxcr2 deletion mutants exhibit significant hearing loss by 3 weeks of age that is associated with developmental defects in stereocilia bundle orientation and organization. Despite these bundle defects, the mechanotransduction apparatus assembles in relatively normal fashion as determined by whole cell electrophysiological evaluation and FM1-43 uptake. Although Grxcr2 mutants do not exhibit overt vestibular dysfunction, evaluation of vestibular evoked potentials revealed subtle defects of the mutants in response to linear accelerations. In addition, reduced Grxcr2 expression in a hypomorphic mutant strain is associated with progressive hearing loss and bundle defects. The stereocilia localization of GRXCR2, together with the bundle pathologies observed in the mutants, indicate that GRXCR2 plays an intrinsic role in bundle orientation, organization, and sensory function in the inner ear during development and at maturity.

PMID: 30157177 [PubMed - in process]

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Grxcr2 is required for stereocilia morphogenesis in the cochlea.

Grxcr2 is required for stereocilia morphogenesis in the cochlea.

PLoS One. 2018;13(8):e0201713

Authors: Avenarius MR, Jung JY, Askew C, Jones SM, Hunker KL, Azaiez H, Rehman AU, Schraders M, Najmabadi H, Kremer H, Smith RJH, Géléoc GSG, Dolan DF, Raphael Y, Kohrman DC

Abstract
Hearing and balance depend upon the precise morphogenesis and mechanosensory function of stereocilia, the specialized structures on the apical surface of sensory hair cells in the inner ear. Previous studies of Grxcr1 mutant mice indicated a critical role for this gene in control of stereocilia dimensions during development. In this study, we analyzed expression of the paralog Grxcr2 in the mouse and evaluated auditory and vestibular function of strains carrying targeted mutations of the gene. Peak expression of Grxcr2 occurs during early postnatal development of the inner ear and GRXCR2 is localized to stereocilia in both the cochlea and in vestibular organs. Homozygous Grxcr2 deletion mutants exhibit significant hearing loss by 3 weeks of age that is associated with developmental defects in stereocilia bundle orientation and organization. Despite these bundle defects, the mechanotransduction apparatus assembles in relatively normal fashion as determined by whole cell electrophysiological evaluation and FM1-43 uptake. Although Grxcr2 mutants do not exhibit overt vestibular dysfunction, evaluation of vestibular evoked potentials revealed subtle defects of the mutants in response to linear accelerations. In addition, reduced Grxcr2 expression in a hypomorphic mutant strain is associated with progressive hearing loss and bundle defects. The stereocilia localization of GRXCR2, together with the bundle pathologies observed in the mutants, indicate that GRXCR2 plays an intrinsic role in bundle orientation, organization, and sensory function in the inner ear during development and at maturity.

PMID: 30157177 [PubMed - in process]

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Hearing Protector Attenuation and Noise Exposure Among Metal Manufacturing Workers

Objectives: This study utilized personal noise measurements and fit-testing to evaluate the association between noise exposures and personal attenuation rating (PAR) values among participating workers, and second, to compare the attenuated exposure levels received by the workers and the British Standards Institute’s recommended noise exposure range of 70 to 80 dBA. Design: We measured hearing protection device (HPD) attenuation among a sample of 91 workers at 2 US metal manufacturing facilities, through performance of personal noise dosimetry measurements and HPD fit-testing over multiple work shifts. We compared this testing with participant questionnaires and annual audiometric hearing threshold results. Results: The average 8-hr time-weighted average noise exposures for study participants was 79.8 dBA (SD = 7.0 dBA), and the average PAR from fit-testing was 20.1 dB (±6.7 dB). While differences existed between sites, 84% of the 251 PAR measurements resulted in effective protection levels below the recommended 70 dBA (indicating overprotection), while workers were underprotected (i.e., effective exposures >80 dBA) during

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Hearing Protector Attenuation and Noise Exposure Among Metal Manufacturing Workers

Objectives: This study utilized personal noise measurements and fit-testing to evaluate the association between noise exposures and personal attenuation rating (PAR) values among participating workers, and second, to compare the attenuated exposure levels received by the workers and the British Standards Institute’s recommended noise exposure range of 70 to 80 dBA. Design: We measured hearing protection device (HPD) attenuation among a sample of 91 workers at 2 US metal manufacturing facilities, through performance of personal noise dosimetry measurements and HPD fit-testing over multiple work shifts. We compared this testing with participant questionnaires and annual audiometric hearing threshold results. Results: The average 8-hr time-weighted average noise exposures for study participants was 79.8 dBA (SD = 7.0 dBA), and the average PAR from fit-testing was 20.1 dB (±6.7 dB). While differences existed between sites, 84% of the 251 PAR measurements resulted in effective protection levels below the recommended 70 dBA (indicating overprotection), while workers were underprotected (i.e., effective exposures >80 dBA) during

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Hearing Loss on the Rise among Oil and Gas Drilling Workers

New data shows that hearing loss is on the rise among oil and gas drilling workers despite their increased use of ear protection.

According to Canada's WorkSafeBC, the workers' hearing test data, collected by their employers, revealed increased incidences of hearing loss, from 33 percent in 2012 to 45 percent in 2017. Notably, 65 percent of the workers diagnosed with noise-induced hearing loss (NIHL; 194 out of 294) were under 35 years old. Adding another level of concern is the finding that the percentage of workers using earplugs has actually increased from 94 to 98 percent.

"In British Columbia, employers are required under the Workers Compensation Act to provide annual hearing tests to their employees who work in hazardous noise (85dBA Lex)," explained Sasha Brown, an occupational audiologist at WorkSafeBC.

"These hearing test results are submitted to WorkSafeBC, and that data, which can be separated by industry or occupation, is continuously analyzed. Attention is paid to hearing test results that show a 15dB notch at 3, 4 or 6 kHz, or a deterioration between tests of 15 dB at 3 or 4 kHz."

WorkSafeBC, an independent statutory agency focused on the prevention of occupational injuries and diseases, receives around 170,000 hearing tests per year, and the percentage of those with hearing loss consistent with NIHL has remained about 13 percent across industries. "The high rate of hearing loss found in the oil and gas industry is much higher, above 30 percent, and for those in oil or gas drilling sector, even higher at 45 percent. This finding is concerning and warranted further investigation," Brown told The Hearing Journal.  

The increased cases of NIHL despite the increased use of hearing protection may be attributed to different reasons, on top of which is the improper use of foam earplugs.

"The earplugs or earmuffs might be the wrong size, inserted or worn incorrectly, not worn for long enough, or they may not be providing enough protection for the duration and intensity of noise exposure," Brown noted.

In their report, WorkSafeBC provides measures for employers to prevent NIHL among their workers, including the monitoring of workers' proper use of sufficient and appropriate hearing protection, encouraging workers to get regular hearing tests, and identifying potential engineering controls to mitigate lessen the risk of noise exposure. "Monitoring one's hearing is also important, and comparing the results from year-to-year to see if there are any changes," said Brown. In addition, she highlights some basic but vital strategies for employers, audiologists, and hearing health professionals, who all play an important role in ensuring the hearing health of workers regularly exposed to noise.

"Educating workers is important. Workers exposed to hazardous noise levels should understand that simply wearing hearing protection might not be enough. The hearing protection must be the right size, and the wearer must be able to fit it properly and wear at all times while in hazardous noise. It must be placed before entering the noisy area, and not removed until leaving the area," stressed Brown. "Obviously, this is also important for noisy hobbies and activities outside work too."

"Workers should be taught what to look for and understand the implications. Unfortunately, hearing tests are the only way to determine if their hearing is being protected. I say 'unfortunately' because this is a lagging indicator and means that some hearing loss has occurred," said Brown. "If audiologists and hearing health professionals can help raise awareness about NIHL and how to prevent it, that alone would contribute to improving the hearing health of oil and gas, and all, workers."

Published: 8/29/2018 1:54:00 PM

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Hearing Loss on the Rise among Oil and Gas Drilling Workers

New data shows that hearing loss is on the rise among oil and gas drilling workers despite their increased use of ear protection.

According to Canada's WorkSafeBC, the workers' hearing test data, collected by their employers, revealed increased incidences of hearing loss, from 33 percent in 2012 to 45 percent in 2017. Notably, 65 percent of the workers diagnosed with noise-induced hearing loss (NIHL; 194 out of 294) were under 35 years old. Adding another level of concern is the finding that the percentage of workers using earplugs has actually increased from 94 to 98 percent.

"In British Columbia, employers are required under the Workers Compensation Act to provide annual hearing tests to their employees who work in hazardous noise (85dBA Lex)," explained Sasha Brown, an occupational audiologist at WorkSafeBC.

"These hearing test results are submitted to WorkSafeBC, and that data, which can be separated by industry or occupation, is continuously analyzed. Attention is paid to hearing test results that show a 15dB notch at 3, 4 or 6 kHz, or a deterioration between tests of 15 dB at 3 or 4 kHz."

WorkSafeBC, an independent statutory agency focused on the prevention of occupational injuries and diseases, receives around 170,000 hearing tests per year, and the percentage of those with hearing loss consistent with NIHL has remained about 13 percent across industries. "The high rate of hearing loss found in the oil and gas industry is much higher, above 30 percent, and for those in oil or gas drilling sector, even higher at 45 percent. This finding is concerning and warranted further investigation," Brown told The Hearing Journal.  

The increased cases of NIHL despite the increased use of hearing protection may be attributed to different reasons, on top of which is the improper use of foam earplugs.

"The earplugs or earmuffs might be the wrong size, inserted or worn incorrectly, not worn for long enough, or they may not be providing enough protection for the duration and intensity of noise exposure," Brown noted.

In their report, WorkSafeBC provides measures for employers to prevent NIHL among their workers, including the monitoring of workers' proper use of sufficient and appropriate hearing protection, encouraging workers to get regular hearing tests, and identifying potential engineering controls to mitigate lessen the risk of noise exposure. "Monitoring one's hearing is also important, and comparing the results from year-to-year to see if there are any changes," said Brown. In addition, she highlights some basic but vital strategies for employers, audiologists, and hearing health professionals, who all play an important role in ensuring the hearing health of workers regularly exposed to noise.

"Educating workers is important. Workers exposed to hazardous noise levels should understand that simply wearing hearing protection might not be enough. The hearing protection must be the right size, and the wearer must be able to fit it properly and wear at all times while in hazardous noise. It must be placed before entering the noisy area, and not removed until leaving the area," stressed Brown. "Obviously, this is also important for noisy hobbies and activities outside work too."

"Workers should be taught what to look for and understand the implications. Unfortunately, hearing tests are the only way to determine if their hearing is being protected. I say 'unfortunately' because this is a lagging indicator and means that some hearing loss has occurred," said Brown. "If audiologists and hearing health professionals can help raise awareness about NIHL and how to prevent it, that alone would contribute to improving the hearing health of oil and gas, and all, workers."

Published: 8/29/2018 1:54:00 PM

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