20Q: Tinnitus and Hyperacusis - Beyond the Ear

As auditory neuroscientists, we are mainly concerned with the way in which the different dimensions of sound (e.g., intensity, frequency and time) activate specific regions of the peripheral or central auditory system. We become “auditory-centric” and ignore the fact that most regions of the central auditory pathway receive inputs and send outputs to many nonauditory centers involved with emotion, memory, body position, vision, touch and likely many other regions. By integrating many different types of information, we are able to carry out complex activities such as turning our head, torso and eyes towards a loud warning sound that induces fear or anxiety and increases our heart rate.

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20Q: Tinnitus and Hyperacusis - Beyond the Ear

As auditory neuroscientists, we are mainly concerned with the way in which the different dimensions of sound (e.g., intensity, frequency and time) activate specific regions of the peripheral or central auditory system. We become “auditory-centric” and ignore the fact that most regions of the central auditory pathway receive inputs and send outputs to many nonauditory centers involved with emotion, memory, body position, vision, touch and likely many other regions. By integrating many different types of information, we are able to carry out complex activities such as turning our head, torso and eyes towards a loud warning sound that induces fear or anxiety and increases our heart rate.

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20Q: Tinnitus and Hyperacusis - Beyond the Ear

As auditory neuroscientists, we are mainly concerned with the way in which the different dimensions of sound (e.g., intensity, frequency and time) activate specific regions of the peripheral or central auditory system. We become “auditory-centric” and ignore the fact that most regions of the central auditory pathway receive inputs and send outputs to many nonauditory centers involved with emotion, memory, body position, vision, touch and likely many other regions. By integrating many different types of information, we are able to carry out complex activities such as turning our head, torso and eyes towards a loud warning sound that induces fear or anxiety and increases our heart rate.

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Effects of high intensity noise on the vestibular system in rats.

Related Articles

Effects of high intensity noise on the vestibular system in rats.

Hear Res. 2016 Mar 9;

Authors: Stewart C, Yu Y, Huang J, Maklad A, Tang X, Allison J, Mustain W, Zhou W, Zhu H

Abstract
Some individuals with noise-induced hearing loss (NIHL) also report balance problems. These accompanying vestibular complaints are not well understood. The present study used a rat model to examine the effects of noise exposure on the vestibular system. Rats were exposed to continuous broadband white noise (0-24kHz) at an intensity of 116dB sound pressure level (SPL) via insert ear phones in one ear for three hours under isoflurane anesthesia. Seven days after the exposure, a significant increase in ABR threshold (43.3+1.9dB) was observed in the noise-exposed ears, indicating hearing loss. Effects of noise exposure on vestibular function were assessed by three approaches. First, fluorescein-conjugated phalloidin staining was used to assess vestibular stereocilia following noise exposure. This analysis revealed substantial sensory stereocilia bundle loss in the saccular and utricular maculae as well as in the anterior and horizontal semicircular canal cristae, but not in the posterior semicircular canal cristae. Second, single unit recording of vestibular afferent activity was performed under pentobarbital anesthesia. A total of 548 afferents were recorded from 10 noise-treated rats and 12 control rats. Noise exposure produced a moderate reduction in baseline firing rates of regular otolith afferents and anterior semicircular canal afferents. Also a moderate change was noted in the gain and phase of the horizontal and anterior semicircular canal afferent's response to sinusoidal head rotation (1 and 2Hz, 45 degrees/s peak velocity). Third, noise exposure did not result in significant changes in gain or phase of the horizontal rotational and translational vestibular-ocular reflex (VOR). These results suggest that noise exposure not only causes hearing loss, but also causes substantial damage in the peripheral vestibular system in the absence of immediate clinically measurable vestibular signs. These peripheral deficits, however, may lead to vestibular disorders over time.

PMID: 26970474 [PubMed - as supplied by publisher]

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Protective effects of the seaweed phlorotannin polyphenolic compound dieckol on gentamicin-induced damage in auditory hair cells.

Related Articles

Protective effects of the seaweed phlorotannin polyphenolic compound dieckol on gentamicin-induced damage in auditory hair cells.

Int J Pediatr Otorhinolaryngol. 2016 Apr;83:31-6

Authors: Chang MY, Byon SH, Shin HC, Han SE, Kim JY, Byun JY, Lee JD, Park MK

Abstract
OBJECTIVES: Drug-induced ototoxicity from compounds such as aminoglycosides and platinum can damage the inner ear resulting in hearing loss, tinnitus or balance problems and may be caused by the formation of reactive oxygen species (ROS). Dieckol is a phlorotannin polyphenolic compound with strong antioxidant effects found in edible brown algae. This study investigated the protective effects of dieckol on drug-induced ototoxicity in cochlear cultures obtained from neonatal mice.
METHODS: Cochlear explants were pretreated with dieckol and exposed to gentamicin for 48h. The explants were then fixed and stained with fluorescein isothiocyanate-phalloidin and the intact hair cells counted. The free radical scavenging activity of dieckol was assessed using a 1,1-diphenyl-2-picrylhydrazyl assay. E. coli (Escherichia coli) cultures were used to evaluate the effect of dieckol on the antibiotic activity of gentamicin.
RESULTS: Gentamicin treatment resulted in dose-dependent hair cell loss that was partially protected by dieckol. Moreover, at concentrations >67μM dieckol had significant radical scavenging activity. Dieckol did not compromise the antibiotic effect of gentamicin.
CONCLUSIONS: These findings suggest that dieckol can be used as a therapeutic agent that reduces the damage caused by drug-induced ototoxicity.

PMID: 26968049 [PubMed - in process]

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Effects of high intensity noise on the vestibular system in rats.

Related Articles

Effects of high intensity noise on the vestibular system in rats.

Hear Res. 2016 Mar 9;

Authors: Stewart C, Yu Y, Huang J, Maklad A, Tang X, Allison J, Mustain W, Zhou W, Zhu H

Abstract
Some individuals with noise-induced hearing loss (NIHL) also report balance problems. These accompanying vestibular complaints are not well understood. The present study used a rat model to examine the effects of noise exposure on the vestibular system. Rats were exposed to continuous broadband white noise (0-24kHz) at an intensity of 116dB sound pressure level (SPL) via insert ear phones in one ear for three hours under isoflurane anesthesia. Seven days after the exposure, a significant increase in ABR threshold (43.3+1.9dB) was observed in the noise-exposed ears, indicating hearing loss. Effects of noise exposure on vestibular function were assessed by three approaches. First, fluorescein-conjugated phalloidin staining was used to assess vestibular stereocilia following noise exposure. This analysis revealed substantial sensory stereocilia bundle loss in the saccular and utricular maculae as well as in the anterior and horizontal semicircular canal cristae, but not in the posterior semicircular canal cristae. Second, single unit recording of vestibular afferent activity was performed under pentobarbital anesthesia. A total of 548 afferents were recorded from 10 noise-treated rats and 12 control rats. Noise exposure produced a moderate reduction in baseline firing rates of regular otolith afferents and anterior semicircular canal afferents. Also a moderate change was noted in the gain and phase of the horizontal and anterior semicircular canal afferent's response to sinusoidal head rotation (1 and 2Hz, 45 degrees/s peak velocity). Third, noise exposure did not result in significant changes in gain or phase of the horizontal rotational and translational vestibular-ocular reflex (VOR). These results suggest that noise exposure not only causes hearing loss, but also causes substantial damage in the peripheral vestibular system in the absence of immediate clinically measurable vestibular signs. These peripheral deficits, however, may lead to vestibular disorders over time.

PMID: 26970474 [PubMed - as supplied by publisher]

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Protective effects of the seaweed phlorotannin polyphenolic compound dieckol on gentamicin-induced damage in auditory hair cells.

Related Articles

Protective effects of the seaweed phlorotannin polyphenolic compound dieckol on gentamicin-induced damage in auditory hair cells.

Int J Pediatr Otorhinolaryngol. 2016 Apr;83:31-6

Authors: Chang MY, Byon SH, Shin HC, Han SE, Kim JY, Byun JY, Lee JD, Park MK

Abstract
OBJECTIVES: Drug-induced ototoxicity from compounds such as aminoglycosides and platinum can damage the inner ear resulting in hearing loss, tinnitus or balance problems and may be caused by the formation of reactive oxygen species (ROS). Dieckol is a phlorotannin polyphenolic compound with strong antioxidant effects found in edible brown algae. This study investigated the protective effects of dieckol on drug-induced ototoxicity in cochlear cultures obtained from neonatal mice.
METHODS: Cochlear explants were pretreated with dieckol and exposed to gentamicin for 48h. The explants were then fixed and stained with fluorescein isothiocyanate-phalloidin and the intact hair cells counted. The free radical scavenging activity of dieckol was assessed using a 1,1-diphenyl-2-picrylhydrazyl assay. E. coli (Escherichia coli) cultures were used to evaluate the effect of dieckol on the antibiotic activity of gentamicin.
RESULTS: Gentamicin treatment resulted in dose-dependent hair cell loss that was partially protected by dieckol. Moreover, at concentrations >67μM dieckol had significant radical scavenging activity. Dieckol did not compromise the antibiotic effect of gentamicin.
CONCLUSIONS: These findings suggest that dieckol can be used as a therapeutic agent that reduces the damage caused by drug-induced ototoxicity.

PMID: 26968049 [PubMed - in process]

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Expanding the Genotypic Spectrum of Perrault syndrome.

Expanding the Genotypic Spectrum of Perrault syndrome.

Clin Genet. 2016 Mar 11;

Authors: Demain LA, Urquhart JE, O'Sullivan J, Williams SG, Bhaskar SS, Jenkinson EM, Lourenco CM, Heiberg A, Pearce SH, Shalev SA, Yue WW, Mackinnon S, Munro KJ, Newbury-Ecob R, Becker K, Kim MJ, O' Keefe RT, Newman WG

Abstract
Perrault syndrome is a rare autosomal recessive disorder characterised by sensorineural hearing loss (SNHL) in both sexes and primary ovarian insufficiency in 46, XX karyotype females. Biallelic variants in five genes are reported to be causative: HSD17B4, HARS2, LARS2, CLPP and C10orf2. Here we present eight families affected by Perrault syndrome. In five families we identified novel or previously reported variants in HSD17B4, LARS2, CLPP and C10orf2. The proband from each family was whole exome sequenced and variants confirmed by Sanger sequencing. A female was compound heterozygous for a known, p.(Gly16Ser) and novel, p.(Val82Phe) variant in D-bifunctional protein (HSD17B4). A family was homozygous for mtLeuRS (LARS2) p.(Thr522Asn), previously associated with Perrault syndrome. A further family was compound heterozygous for mtLeuRS, p.(Thr522Asn) and a novel variant, p.(Met117Ile). Affected individuals with LARS2 variants had low frequency SNHL, a feature previously described in Perrault syndrome. A female with significant neurological disability was compound heterozygous for p.(Arg323Gln) and p.(Asn399Ser) variants in Twinkle (C10orf2). A male was homozygous for a novel variant in CLPP, p.(Cys144Arg). In three families there were no putative pathogenic variants in these genes confirming additional disease-causing genes remain unidentified. We have expanded the spectrum of disease-causing variants associated with Perrault syndrome.

PMID: 26970254 [PubMed - as supplied by publisher]

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Comprehensive genetic testing in the clinical evaluation of 1119 patients with hearing loss.

Comprehensive genetic testing in the clinical evaluation of 1119 patients with hearing loss.

Hum Genet. 2016 Mar 11;

Authors: Sloan-Heggen CM, Bierer AO, Shearer AE, Kolbe DL, Nishimura CJ, Frees KL, Ephraim SS, Shibata SB, Booth KT, Campbell CA, Ranum PT, Weaver AE, Black-Ziegelbein EA, Wang D, Azaiez H, Smith RJ

Abstract
Hearing loss is the most common sensory deficit in humans, affecting 1 in 500 newborns. Due to its genetic heterogeneity, comprehensive diagnostic testing has not previously been completed in a large multiethnic cohort. To determine the aggregate contribution inheritance makes to non-syndromic hearing loss, we performed comprehensive clinical genetic testing with targeted genomic enrichment and massively parallel sequencing on 1119 sequentially accrued patients. No patient was excluded based on phenotype, inheritance or previous testing. Testing resulted in identification of the underlying genetic cause for hearing loss in 440 patients (39 %). Pathogenic variants were found in 49 genes and included missense variants (49 %), large copy number changes (18 %), small insertions and deletions (18 %), nonsense variants (8 %), splice-site alterations (6 %), and promoter variants (<1 %). The diagnostic rate varied considerably based on phenotype and was highest for patients with a positive family history of hearing loss or when the loss was congenital and symmetric. The spectrum of implicated genes showed wide ethnic variability. These findings support the more efficient utilization of medical resources through the development of evidence-based algorithms for the diagnosis of hearing loss.

PMID: 26969326 [PubMed - as supplied by publisher]

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Novel compound heterozygous mutations in MYO7A gene associated with autosomal recessive sensorineural hearing loss in a Chinese family.

Novel compound heterozygous mutations in MYO7A gene associated with autosomal recessive sensorineural hearing loss in a Chinese family.

Int J Pediatr Otorhinolaryngol. 2016 Apr;83:179-85

Authors: Ma Y, Xiao Y, Zhang F, Han Y, Li J, Xu L, Bai X, Wang H

Abstract
OBJECTIVES: Mutations in MYO7A gene have been reported to be associated with Usher Syndrome type 1B (USH1B) and nonsyndromic hearing loss (DFNB2, DFNA11). Most mutations in MYO7A gene caused USH1B, whereas only a few reported mutations led to DFNB2 and DFNA11. The current study was designed to investigate the mutations among a Chinese family with autosomal recessive hearing loss.
METHODS: In this study, we present the clinical, genetic and molecular characteristics of a Chinese family. Targeted capture of 127 known deafness genes and next-generation sequencing were employed to study the genetic causes of two siblings in the Chinese family. Sanger sequencing was employed to examine those variant mutations in the members of this family and other ethnicity-matched controls.
RESULTS: We identified the novel compound heterozygous mutant alleles of MYO7A gene: a novel missense mutation c.3671C>A (p.A1224D) and a reported insert mutation c.390_391insC (p.P131PfsX9). Variants were further confirmed by Sanger sequencing. These two compound heterozygous variants were co-segregated with autosomal recessive hearing loss phenotype. The gene mutation analysis and protein sequence alignment further supported that the novel compound heterozygous mutations were pathogenic.
CONCLUSION: The novel compound heterozygous mutations (c.3671C>A and c.390_391insC) in MYO7A gene identified in this study were responsible for the autosomal recessive sensorineural hearing loss of this Chinese family.

PMID: 26968074 [PubMed - in process]

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