Association of Conductive Hearing Loss with the Structural Changes in the Organ of Corti

ORL ◽  
2021 ◽  
pp. 1-8
Author(s):  
Sinan Eroglu ◽  
Rasit Cevizci ◽  
Handan Turan Dizdar ◽  
Hasan Deniz Tansuker ◽  
Erdogan Bulut ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inner Ear ◽  
Cell Morphology ◽  
Hair Cells ◽  
Structural Changes ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

<b><i>Objective:</i></b> The aim of the study was to evaluate the association of conductive hearing loss (CHL) with the structural changes in the organ of Corti. <b><i>Methods:</i></b> Twenty ears of 10 healthy adult Wistar albino rats were included in the study. The right ears (<i>n</i> = 10) of the animals served as controls (group 1), and no surgical intervention was performed in these ears. A tympanic membrane perforation without annulus removal was performed under operative microscope on the left ears (<i>n</i> = 5) in 5 of 10 animals (group 2). A tympanic membrane perforation with annulus removal was performed under operative microscope on the left ears (<i>n</i> = 5) of the remaining 5 animals (group 3). Auditory brainstem response testing was performed in the animals before the interventions. After 3 months, the animals were sacrificed, their temporal bones were removed, and inner ears were investigated using scanning electron microscopy (SEM). The organ of Corti was evaluated from the cochlear base to apex in the modiolar axis, and the parameters were scored semiquantitatively. <b><i>Results:</i></b> In group 1, the pre- and post-intervention hearing thresholds were similar (<i>p</i> &#x3e; 0.05). In group 2, a hearing decrease of at least 5 dB was encountered in all test frequencies (<i>p</i> &#x3e; 0.05). In group 3, at the frequency range of 2–32 kHz, there was a significant hearing loss after 3 months (<i>p</i> &#x3c; 0.01). After 3 months, the hearing thresholds in group 2 and 3 were higher than group 1 (<i>p</i> &#x3c; 0.01). The hearing threshold in group 3 was higher than group 2 (<i>p</i> &#x3c; 0.01). On SEM evaluation, the general cell morphology and stereocilia of the outer hair cells were preserved in all segments of the cochlea in group 1 with a mean SEM score of 0.2. There was segmental degeneration in the general cell morphology and outer hair cells in group 2 with a mean SEM score of 2.2. There was widespread degeneration in the general cell morphology and outer hair cells in group 3 with a mean SEM score of 3.2. The SEM scores of group 2 and 3 were significantly higher than group 1 (<i>p</i> &#x3c; 0.05). The SEM scores of group 3 were significantly higher than group 2 (<i>p</i> &#x3c; 0.05). <b><i>Conclusion:</i></b> CHL may be associated with an inner ear damage. The severity of damage appears to be associated with severity and duration of CHL. Early correction of CHL is advocated in order to reverse or prevent progression of the inner ear damage, which will enhance the success rates of hearing restoration surgeries. Subjective differences and compliance of the hearing aid users may be due to the impact of CHL on inner ear structures.

scholarly journals Aquaporin-6 Expression in the Cochlear Sensory Epithelium Is Downregulated by Salicylates

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Paola Perin ◽  
Simona Tritto ◽  
Laura Botta ◽  
Jacopo Maria Fontana ◽  
Giulia Gastaldi ◽  
...  
Keyword(s):  
Inner Ear ◽  
Expression Pattern ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Sensory Epithelium ◽  
Outer Hair Cells ◽  
Rt Pcr ◽  
Supporting Cells ◽  
Sensory Epithelia ◽  
Mechanical Compliance

We characterize the expression pattern of aquaporin-6 in the mouse inner ear by RT-PCR and immunohistochemistry. Our data show that in the inner ear aquaporin-6 is expressed, in both vestibular and acoustic sensory epithelia, by the supporting cells directly contacting hair cells. In particular, in the Organ of Corti, expression was strongest in Deiters' cells, which provide both a mechanical link between outer hair cells (OHCs) and the Organ of Corti, and an entry point for ion recycle pathways. Since aquaporin-6 is permeable to both water and anions, these results suggest its possible involvement in regulating OHC motility, directly through modulation of water and chloride flow or by changing mechanical compliance in Deiters' cells. In further support of this role, treating mice with salicylates, which impair OHC electromotility, dramatically reduced aquaporin-6 expression in the inner ear epithelia but not in control tissues, suggesting a role for this protein in modulating OHCs' responses.

scholarly journals Static length changes of cochlear outer hair cells can tune low-frequency hearing

2017 ◽  
Author(s):  
Nikola Ciganović ◽  
Rebecca L. Warren ◽  
Batu Keçeli ◽  
Stefan Jacob ◽  
Anders Fridberger ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Frequency Selectivity ◽  
Apical Region ◽  
Low Frequencies ◽  
Inner Hair Cells ◽  
Length Changes ◽  
The Brain

AbstractThe cochlea not only transduces sound-induced vibration into neural spikes, it also amplifies weak sound to boost its detection. Actuators of this active process are sensory outer hair cells in the organ of Corti, whereas the inner hair cells transduce the resulting motion into electric signals that propagate via the auditory nerve to the brain. However, how the outer hair cells modulate the stimulus to the inner hair cells remains unclear. Here, we combine theoretical modeling and experimental measurements near the cochlear apex to study the way in which length changes of the outer hair cells deform the organ of Corti. We develop a geometry-based kinematic model of the apical organ of Corti that reproduces salient, yet counter-intuitive features of the organ’s motion. Our analysis further uncovers a mechanism by which a static length change of the outer hair cells can sensitively tune the signal transmitted to the sensory inner hair cells. When the outer hair cells are in an elongated state, stimulation of inner hair cells is largely inhibited, whereas outer hair cell contraction leads to a substantial enhancement of sound-evoked motion near the hair bundles. This novel mechanism for regulating the sensitivity of the hearing organ applies to the low frequencies that are most important for the perception of speech and music. We suggest that the proposed mechanism might underlie frequency discrimination at low auditory frequencies, as well as our ability to selectively attend auditory signals in noisy surroundings.Author summaryOuter hair cells are highly specialized force producers inside the inner ear: they can change length when stimulated electrically. However, how exactly this electromotile effect contributes to the astonishing sensitivity and frequency selectivity of the inner ear has remained unclear. Here we show for the first time that static length changes of outer hair cells can sensitively regulate how much of a sound signal is passed on to the inner hair cells that forward the signal to the brain. Our analysis holds for the apical region of the inner ear that is responsible for detecting the low frequencies that matter most in speech and music. This shows a mechanisms for how frequency-selectivity can be achieved at low frequencies. It also opens a path for the efferent neural system to regulate hearing sensitivity.

scholarly journals A Natural Occurring Mouse Model with Adgrv1 Mutation of Usher Syndrome 2C and Characterization of its Recombinant Inbred Strains

2018 ◽  
Vol 47 (5) ◽  
pp. 1883-1897 ◽  
Author(s):  
Weiming Yan ◽  
Pan Long ◽  
Tao Chen ◽  
Wei Liu ◽  
Lu Yao ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inner Ear ◽  
Retinal Degeneration ◽  
Western Blotting ◽  
Hair Cells ◽  
Recombinant Inbred ◽  
Usher Syndrome ◽  
Inbred Strains ◽  
Outer Hair Cells ◽  
Recombinant Inbred Strains

Background/Aims: Our laboratory discovered a Kunming mouse with enormous electroretinogram (ERG) defects. Its auditory brainstem response (ABR) threshold was significantly elevated and closely resembled the features of Usher syndrome (USH). This study sought to cross these USH-like mice (named KMush/ush mice) with CBA/CaJ mice to establish recombinant inbred strains and identify their phenotypes and genotypes. Methods: KMush/ush mice were crossed with CBA/CaJ mice to establish inbred strains by sibling mating. ERG, ABR, ocular fundus morphology, histological examinations of the retina and inner ear, quantitative real-time polymerase chain reaction, western blotting, and exon sequencing were performed to assess the phenotypes and genotypes of the offspring strains. Results: The F1 hybrids from crossing KMush/ush and CBA/CaJ mice had normal ERG and ABR responses. The F2 offspring from intercrossing the F1 mice showed a segregation of the retinitis pigmentosa (RP) and hearing loss phenotypes. The CBA-1ush/ush mice had an RP phenotype that was characterized by a vanished ERG waveform and loss of the outer nuclear layer. Their Pde6b gene had a nonsense mutation that resulted in the failure of protein production in western blotting. However, the ABR threshold of this strain of mice was normal. The CBA-2ush/ush mice had normal retinal function and architecture. Their ABR threshold was increased, with a dramatic degeneration of the stereocilia bundles in the outer hair cells of the inner ear. Whole exome sequencing and exon sequencing revealed a deletion of one base pair in exon 31 of the Adgrv1 gene, which would result in the premature termination of protein encoding. The level of Adgrv1 mRNA was reduced in the CBA-2ush/ush mice. The CBA-3ush/ush mice had phenotypes of RP, elevated ABR threshold, and degeneration of the stereocilia bundles in the outer hair cells. They were closely associated with the nonsense mutations of Pde6b and Adgrv1, respectively. Conclusion: We isolated a mouse strain with hearing loss from inbred mice with retinal degeneration and established it as a recombinant inbred strain with a spontaneous mutation in Adgrv1, the human Usher syndrome 2C gene. The retinal degeneration was cause by a mutation in Pde6b, while the hearing loss was caused by a mutation in Adgrv1.

scholarly journals Elmod3 knockout leads to progressive hearing loss and abnormalities in cochlear hair cell stereocilia

2019 ◽  
Vol 28 (24) ◽  
pp. 4103-4112 ◽  
Author(s):  
Wu Li ◽  
Yong Feng ◽  
Anhai Chen ◽  
Taoxi Li ◽  
Sida Huang ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Actin Cytoskeleton ◽  
Hearing Impairment ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Vestibular Function ◽  
Outer Hair Cells ◽  
Auditory Function ◽  
Cochlear Hair Cells

Abstract ELMOD3, an ARL2 GTPase-activating protein, is implicated in causing hearing impairment in humans. However, the specific role of ELMOD3 in auditory function is still far from being elucidated. In the present study, we used the CRISPR/Cas9 technology to establish an Elmod3 knockout mice line in the C57BL/6 background (hereinafter referred to as Elmod3−/− mice) and investigated the role of Elmod3 in the cochlea and auditory function. Elmod3−/− mice started to exhibit hearing loss from 2 months of age, and the deafness progressed with aging, while the vestibular function of Elmod3−/− mice was normal. We also observed that Elmod3−/− mice showed thinning and receding hair cells in the organ of Corti and much lower expression of F-actin cytoskeleton in the cochlea compared with wild-type mice. The deafness associated with the mutation may be caused by cochlear hair cells dysfunction, which manifests with shortening and fusion of inner hair cells stereocilia and progressive degeneration of outer hair cells stereocilia. Our finding associates Elmod3 deficiencies with stereocilia dysmorphologies and reveals that they might play roles in the actin cytoskeleton dynamics in cochlear hair cells, and thus relate to hearing impairment.

scholarly journals Prevalence of Hearing Loss in Type 2 Diabetes Mellitus and Its Association with Severity of Diabetic Neuropathy

2022 ◽  
Author(s):  
Abin M Abraham ◽  
Ashish Varghese ◽  
Jubbin Jagan Jacob
Keyword(s):  
Type 2 Diabetes ◽  
Hearing Loss ◽  
Diabetic Neuropathy ◽  
Hearing Threshold ◽  
Self Report ◽  
Increased Risk ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Abstract Purpose This study assessed the prevalence of hearing loss (HL) in patients with Type 2 Diabetes (T2DM) and its relationship with the presence and severity of diabetic neuropathy. Methods Patients between the ages of 30 to 60 years (both ages inclusive) with T2DM were recruited and divided into three groups. Group 1 included patients without neuropathy. Group 2 had patients with mild neuropathy. Group 3 had patients with moderate and severe neuropathy. After informed consent hearing threshold was assessed using pure tone audiometry (PTA). Results Of the 200 patients recruited, the prevalence of hearing loss was overall 81%. The prevalence was 66.7% in group 1, 80.9% in group 2 and 87.6% in group 3 (p=0.009). Among patients with moderate to severe neuropathy (group 3) 33.3% had clinically significant hearing loss (p=0.015). Age, gender, presence of neuropathy and severity of neuropathy were associated with increased risk of developing hearing loss. Severity of hearing loss worsened with increase in severity of neuropathy. Conclusions Age, gender and severity of neuropathy were associated with increased risk of developing hearing loss. Screening for hearing loss in patients with moderate to severe diabetic neuropathy using self-report questionnaires can help in timely diagnosis and treatment.

scholarly journals Dynamic of radiographic and ultrasonographic indices of hip joints in patients with ankylosing spondylitis under treatment with tumor necrotic factor ― alpha inhibitors

2020 ◽  
Vol 2 (37) ◽  
pp. 54-58
Author(s):  
A. V. Petrov ◽  
Y. O. Shevnina ◽  
A. S. Gaffarova ◽  
A. A. Petrov
Keyword(s):  
Ankylosing Spondylitis ◽  
Synovial Membrane ◽  
Structural Changes ◽  
Dynamic Monitoring ◽  
Hip Joints ◽  
Hip Arthritis ◽  
Factor Alpha ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Background. Inflammation of the hip joints in ankylosing spondylitis (AS) is a frequent and severe manifestation of the disease, which in 7–8 % of patients is accompanied by the requirements of hip joints prosthesis. In the treatment of hip arthritis associated with AS non-steroidal anti-inflammatory drugs (NSAIDs), sulfasalazine (SSZ) and tumor necrosis factor-alpha blockers were used. However, the influence of these treatment on the dynamics of structural changes in hip joints is not studied.Purpose. To evaluate the dynamics of clinical, radiologic and ultrasonographic indices of hip joints in patients with AS who take different treatment methods for 12 months: NSAIDs, SSZ and adalimumab (ADA).Materials and methods. Dynamic monitoring of 78 patients with AS (corresponding to the New York modified criteria of 1984), who also had clinical, ultrasonographic and radiographic signs of inflammation of hip joints. The patients were divided into three groups: patients of the group 1 (n = 25) were been receiving NSAIDs; patients of group 2 (n = 26) had started to take SSZ (2–3 grams per day) on background of NSAIDs; patients of group 3 (n = 27) were started to take ADA (subcutaneously, 40 mg once every 2 weeks) on the background of NSAID. In addition to the generally accepted clinical and laboratory studies, all patients were being underwent by X-ray examination with an evaluation of the BASRI-Hip index and ultrasonography of hip joints during 12 months of follow-up.Results and discussion. In patients of group 2 treatment with SSZ during 12 months had been resulted in a decrease in the severity of pain from the visual analogue scale (VAS) at hip joint motion (26.1 [13.9, 42.7] vs 69.3 [56.8, 79, 3]), CRP (4.4 [1.5, 6.9] mg/L vs 15.2 [8.3, 21.8] mg/L) and a decrease in the thickness of the hip synovial membrane (6.7 [5.8, 8.5] mm vs 9.6 [7.9, 11.8] mm) compared with the initial data. In patients of the group 3 treatment with ADA had been lead to decreasing of pain VAS (14.2 [5.2, 26.7], vs. 72.1 [65.3, 89.1], BASDAI and ASDASCRP (1.7 [1.1, 3.1] and 1.4 [1.1, 2.2] vs. 7.5 [5.9, 8.6] and 3.1 [2.6, 3.9]), CRP (2.7 [0.2, 5.8] mg/L vs. 24.3 [17.4, 35.9]) and decrease in the thickness of hip synovial membrane (6.3 [5.0, 7.7] mm vs. 9.9 [8.1, 12.6] mm) and an increase of the thickness of the hyaline cartilage covering the head of the femur in comparison with group 1 (0.15 [0.09; 0.22] mm vs. —0.08 [–0.12, —0.04] mm). The effect of both drugs on the dynamics of the radiographic index BASRI-Hip and the formation of new osteophytes in hip joints was not noted.Conclusion. Inclusion of SSZ and ADA in a complex of treatment of patients with hip arthritis associated with AS leads to a decrease of synovitis of hip joints. Usage of ADA is accompanies by ultrasonographic signs of the restoration of hip joints cartilage.

scholarly journals Immunohistochemistry localises myosin-7a to cochlear efferent boutons

2022 ◽  
Vol 7 ◽  
pp. 1
Author(s):  
Piotr Sirko ◽  
Andrei S. Kozlov
Keyword(s):  
Hearing Loss ◽  
Vestibular System ◽  
Hair Cells ◽  
Usher Syndrome ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Actin Binding ◽  
Adult Rat ◽  
Cochlear Gain ◽  
Medial Olivocochlear

Background: Myosin 7a is an actin-binding motor protein involved in the formation of hair-cell stereocilia both in the cochlea and in the vestibular system. Mutations in myosin 7a are linked to congenital hearing loss and are present in 50% of Type-1 Usher syndrome patients who suffer from progressive hearing loss and vestibular system dysfunction. Methods: Myosin 7a is often used to visualise sensory hair cells due to its well characterised and localised expression profile. We thus conducted myosin-7a immunostaining across all three turns of the adult rat organ of Corti to visualise hair cells. Results: As expected, we observed myosin 7a staining in both inner and outer hair cells. Unexpectedly, we also observed strong myosin 7a staining in the medial olivocochlear efferent synaptic boutons contacting the outer hair cells. Efferent bouton myosin-7a staining was present across all three turns of the cochlea. We verified this localisation by co-staining with a known efferent bouton marker, the vesicular acetylcholine transporter. Conclusions: In addition to its role in stereocilia formation and maintenance, myosin 7a or certain myosin-7a expression variants might play a role in efferent synaptic transmission in the cochlea and thus ultimately influence cochlear gain regulation. Our immunohistochemistry results should be validated with other methods to confirm these serendipitous findings.

Macrophage inflammatory proteins in cytomegalovirus-related inner ear injury

2007 ◽  
Vol 137 (4) ◽  
pp. 612-618 ◽  
Author(s):  
Scott A. Schraff ◽  
Mark R. Schleiss ◽  
David K. Brown ◽  
Jareen Meinzen-Derr ◽  
K. Yeon Choi ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inner Ear ◽  
Inflammatory Protein ◽  
Group 3 ◽  
Inflammatory Proteins ◽  
Virally Encoded ◽  
Group 2 ◽  
Ear Injury ◽  
Temporal Bones ◽  
Macrophage Inflammatory Protein

Objective Inner ear inflammation triggered by CMV infection may play a role in CMV-related auditory pathogenesis. The purpose of the study was to determine if a virally encoded macrophage inflammatory protein played a role in CMV-related hearing loss. Design Mutagenesis was performed with deletion of a guinea pig CMV macrophage inflammatory protein. Intracochlear inoculations were performed on three groups of animals (n = 18). Group 1 received sterile viral media, Group 2 received wild-type CMV virus, and Group 3 received “knockout” (KO) virus with a deleted immunomodulation gene. Baseline and postinoculation ABRs were obtained. ELISA and PCR were performed and temporal bones examined. Subjects Eighteen guinea pigs. Results The KO group had significantly better hearing than the WT group. There were no significant differences between the KO and sham groups. The WT group had significant hearing loss at all frequencies. Inflammation and fibrosis were noted in the WT temporal bones only. Conclusions Virally encoded macrophage inflammatory proteins appear to play a significant role in CMV-related hearing loss.

scholarly journals Cognitive and brain structural changes in long-term oligodendroglial tumor survivors

2019 ◽  
Vol 21 (11) ◽  
pp. 1470-1479 ◽  
Author(s):  
Nuria Cayuela ◽  
Esteban Jaramillo-Jiménez ◽  
Estela Càmara ◽  
Carles Majós ◽  
Noemi Vidal ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Structural Changes ◽  
Volumetric Analysis ◽  
World Health ◽  
Cross Sectional ◽  
Oligodendroglial Tumor ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Abstract Background We identify cognitive impairment and MRI structural brain changes in long-term oligodendroglial tumor survivors treated with radiation therapy (RT) alone (21%) or with chemotherapy (CT) (79%). Methods Oligodendroglial tumor patients (based on the World Health Organization [WHO] 2007 classification) who completed RT ± CT at least 2 years before the study initiation, were classified into 3 groups according to the time treatment was completed: Group 1 = 2–5 years (n = 22), Group 2 = 6–10 years (n = 13), and Group 3 >10 years (n = 13). All patients had a cross-sectional neuropsychological evaluation (n = 48) and a longitudinal volumetric analysis (gray matter [GM; n = 34]) between postsurgical and last follow-up MRI. White matter (WM) changes on MRI were assessed using a qualitative scale. Results There were no differences regarding tumor or treatment-related characteristics between groups. Six of 22 patients (27.3%) in Group 1; 5/13 (38.5%) in Group 2; and 9/13 (69.2%) in Group 3 had cognitive impairment that was considered severe in 3/22 patients (13.6%) in Group 1; 4/13 (30.8%) in Group 2; and 6/13 (46.2%) in Group 3. Patients in Groups 2 and 3 showed significant GM atrophy and more leukoencephalopathy than Group 1. Cognitive deficits were associated with brain atrophy and WM changes. Conclusions Long-term oligodendroglial tumor survivors who underwent standard RT ± CT treatment, mainly >5 years of its completion, present cognitive impairment, especially on memory and executive functions, associated with late GM and WM damage, thus highlighting the need of developing future strategies in patients with oligodendroglial tumor and long expected survival.

Hearing loss caused by progressive degeneration of cochlear hair cells in mice deficient for the Barhl1 homeobox gene

Development ◽  
2002 ◽  
Vol 129 (14) ◽  
pp. 3523-3532 ◽  
Author(s):  
Shengguo Li ◽  
Sandy M. Price ◽  
Hugh Cahill ◽  
David K. Ryugo ◽  
Michael M. Shen ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Inner Ear ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Cochlear Hair Cells ◽  
Sensory Hair ◽  
Progressive Degeneration ◽  
Age Related ◽  
Sensory Hair Cells

The cochlea of the mammalian inner ear contains three rows of outer hair cells and a single row of inner hair cells. These hair cell receptors reside in the organ of Corti and function to transduce mechanical stimuli into electrical signals that mediate hearing. To date, the molecular mechanisms underlying the maintenance of these delicate sensory hair cells are unknown. We report that targeted disruption of Barhl1, a mouse homolog of the Drosophila BarH homeobox genes, results in severe to profound hearing loss, providing a unique model for the study of age-related human deafness disorders. Barhl1 is expressed in all sensory hair cells during inner ear development, 2 days after the onset of hair cell generation. Loss of Barhl1 function in mice results in age-related progressive degeneration of both outer and inner hair cells in the organ of Corti, following two reciprocal longitudinal gradients. Our data together indicate an essential role for Barhl1 in the long-term maintenance of cochlear hair cells, but not in the determination or differentiation of these cells.

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