The molecular mechanisms underpinning auditory neuropathy / 中华耳鼻咽喉头颈外科杂志

Auditory neuropathy (AN) is a hearing disorder where cochlear inner hair cell and/or the auditory nerve function is disrupted while outer hair cell function is normal. It can affect people of all ages, from infancy to adulthood. People with auditory neuropathy may have normal hearing threshold, or hearing loss ranging from mild to severe; they always have poor speech-perception abilities. It is a heterogeneous disorder which can have either congenital or acquired causes. AN may result from specific loss of cochlear inner hair cells, disordered release of neurotransmitters by inner hair cell ribbon synapses, deafferentation accompanying loss of auditory nerve fibers, neural dys-synchrony or conduction block as a result of demyelination of nerve fibers and auditory nerve hypoplasia. Although the definition of AN includes the central part, its incidence is low, and the etiology and pathology are not clear. The present review aimed to provide an overview of the genetic conditions associated with AN and highlight the neural and synaptic mechanism of AN. Possible strategy for treatments of AN was also discussed.

Screening of microRNAs targeting Notch signaling pathway implicated in inner ear development and the role of microRNA-384-5p / 中华耳鼻咽喉头颈外科杂志

Objective@#To screen the key microRNAs targeting Notch signaling pathway in inner ear and investigate its potential regulating function.@*Methods@#The interaction network and the Core-Notch network, involved with key genes in Notch signal pathway and differential-expressed microRNAs in inner ear, were constructed by bioinformatics methods. The important microRNAs in regulating Notch signaling pathway were screened via topological and GO analysis, followed by in vivo and in vitro investigation.@*Results@#MiRNA-384-5p was identified as a key regulator specifically expressed in mouse brain and inner ear, which could down-regulate Notch1. The Notch1 expression was found significantly down-regulated in miRNA-384-5p-mimic-transfected HeLa cells. The dual-luciferase reporter gene assay further confirmed the effect of miRNA-384-5p on the down-regulation of Notch1 and Dll4 in Notch signaling pathway.@*Conclusions@#The Core-Notch network is constructed to screen microRNAs implicated in inner ear development, and miRNA-384-5p is screened and verified to be target-regulating the Notch signaling pathway, which could be the potential target in the regeneration of impaired hair cells.

The experimental study on endoplasmic reticulum stress-participated outer hair cell apoptosis in cadherin 23 gene mutant mice / 中华耳鼻咽喉头颈外科杂志

Objective@#To test the mechanism and upstream pathway of outer hair cell apoptosis in Cadherin 23 (Cdh23) gene mutant mice.@*Method@#The mutant Cdh23erl/erl(erl) mice were collected as the study group, while the C57BL/6J (B6) mice were chosen as the control group. A total of 70 mice per group were used in this study. The study group and control group underwent auditory-evoked brainstem response (ABR) tests at the same age. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to detect outer hair cell(OHC) apoptosis. The qRT-PCR was conducted to test the expression of ER stress markers immunoglobulin-binding protein (BiP) and C/EBP homologous protein (CHOP) mRNA. The expression and location of BiP and CHOP protein in OHC were detected by immunostaining. The expression of BiP protein in cochleae was identified by Western blot. The expression and location of CDH23 protein in OHC were discovered by immunostaining.@*Results@#The ABR thresholds in erl mice were significantly higher than those in B6 mice at the age of 1 and 3 months (both P<0.05). The surface preparation with TUNEL staining confirmed OHC apoptosis in erl mouse cochleae which showed a higher TUNEL positive cell ratio than B6 mouse(t=11.291, P<0.01). The ER stress marker Bip and Chop mRNA were upregulated in the erl mouse inner ear, when compared with those in the B6 mouse(both P<0.05). The BiP protein extracted from the erl mouse cochleae was significantly higher than that of B6 mouse measured by Western blot (t=3.66, P=0.02). Immunostaining showed that BiP and CHOP were highly detected in the OHC in erl mouse cochleae, and was mainly detected in the perinuclear region of OHC. However, a bare BiP and CHOP signal were shown in B6 mouse cochleae. The CDH23 protein was specifically localized at the top of the OHC in B6 mice, indicating the localization of the tip links in hair bundle stereocilia. On the contrary, the CDH23erl protein was found to be localized from the top to the nuclei of the OHC in erl mice. Portions of the CDH23erl proteins failed to reach the top of the hair bundles and remained in the OHC cytoplasm.@*Conclusion@#As the downstream response of the Cdh23 gene mutation, portions of the mutant CDH23erl protein was accumulated in ER lumen resulting in the increase of ER loading and ultimately triggered ER stress and hair cell apoptosis in erl mouse cochleae.

Identification and analysis of the proteins interacted with Prestin in cochlear outer hair cells of guinea pig / 中华耳鼻咽喉头颈外科杂志

Objective@#To explore the regulation and mechanism of Prestin protein by identifying the proteins interacted with Prestin in cochlear outer hair cell(OHC) and analyzing their biological function.@*Methods@#Co-immunoprecipitation combined mass spectrometry technology was used to isolate and identify the proteins interacted with Prestin protein of OHC, bioinformatics was used to construct Prestin protein interaction network. The proteins interacted with Prestin in OHC of guinea pig were determined by matching primary interaction mass spectrometry with protein interaction network, and annotated their functions.@*Results@#The results of co-immunoprecipitation combined with mass spectrometry showed that 116 kinds of credible proteins could interact with Prestin. By constructing Prestin protein interaction network, matching the results of mass spectrometry and analyzing of sub-cellular localization, eight kinds of proteins were confirmed that they interacted with Prestin directly, namely EEF2, HSP90AB1, FN1, FLNA, EEF1A1, HSP90B1, ATP5A1, and ERH, respectively, which were mainly involved in the synthesis and transportation, transmembrane folding and localization, structural stability and signal transduction of Prestin protein.@*Conclusion@#EEF2, HSP90AB1, FN1, FLNA, EEF1A1, HSP90B1, ATP5A1 and ERH provide molecular basis for sensory amplification function of OHCs by participating in biotransformation, transmembrane folding and localization, signal transduction and other biological processes of Prestin protein.

Otoacoustic emissions in young adults exposed to drums noise of a college band / Estudo das emissões otoacústicas em indivíduos expostos a ruído de bateria universitária

ABSTRACT Purpose: to identify cochlear dysfunction and occurrence of tinnitus in young adults exposed to drums noise of a college band. Methods: the sample included 50 subjects: 25 musicians (study group) and 25 non-musicians (control group). The procedures included anamnesis, pure tone audiometry, acoustic impedance and Transient Evoked Otoacoustic Emissions, Distortion Product Otoacoustic Emissions and Distortion Product Otoacoustic Emissions Input-Output function. Results: positive correlation between the occurrence of tinnitus and the variables exposure time and use of personal stereos was found. Overall, the study group showed significantly lower Transient Evoked Otoacoustic Emissions, when compared to the control group. In the study group, there was a tendency toward worse response in 6 kHz(f2) in Distortion Product Otoacoustic Emissions in both ears. The Distortion Product Otoacoustic Emissions Input-Output function did not differ between groups nor did its slope. Conclusion: in general, otoacoustic emissions were worse in noise-exposed young people (study group) when compared to the unexposed (control group), indicating that the test may be important in early identification of cochlear changes.

RESUMO Objetivo: verificar a ocorrência de alterações da função coclear e de zumbido em indivíduos expostos a ruído de uma bateria universitária. Métodos: a amostra foi composta 50 sujeitos distribuídos em dois grupos: 25 músicos (grupo estudo) e 25 não músicos (grupo controle). Os procedimentos incluíram anamnese, audiometria tonal, vocal, medidas de imitância acústica e Emissões Otoacústicas Evocadas por Estímulo Transiente, produto de distorção e curva de crescimento. Resultados: na anamnese foi identificada correlação positiva entre a ocorrência de zumbido e as variáveis tempo de ensaio e o uso de estéreos pessoais. O grupo estudo apresentou valores de resposta geral das Emissões Otoacústicas Evocadas por Estímulo Transiente significativamente menores, quando comparada ao grupo controle. No grupo estudo, foi observada uma tendência de piores respostas na f2 de 6 kHz no Produto de distorção, em ambas as orelhas. As Curvas de crescimento não diferiram entre os grupos. Não houve diferença entre os grupos com relação aos valores de slope e respostas das curvas de crescimento e Produto de Distorção. Conclusão: as respostas das emissões otoacústicas foram piores nos jovens expostos (grupo estudo), quando comparados aos não expostos (grupo controle) indicando que podem ser um importante instrumento de identificação de alterações iniciais da atividade mecânica da cóclea.

Atoh1 as a Coordinator of Sensory Hair Cell Development and Regeneration in the Cochlea / 전남의대학술지

Cochlear sensory hair cells (HCs) are crucial for hearing as mechanoreceptors of the auditory systems. Clarification of transcriptional regulation for the cochlear sensory HC development is crucial for the improvement of cell replacement therapies for hearing loss. Transcription factor Atoh1 is the key player during HC development and regeneration. In this review, we will focus on Atoh1 and its related signaling pathways (Notch, fibroblast growth factor, and Wnt/β-catenin signaling) involved in the development of cochlear sensory HCs. We will also discuss the potential applicability of these signals for the induction of HC regeneration.

Atoh1 as a Coordinator of Sensory Hair Cell Development and Regeneration in the Cochlea / 전남의대학술지

Cochlear sensory hair cells (HCs) are crucial for hearing as mechanoreceptors of the auditory systems. Clarification of transcriptional regulation for the cochlear sensory HC development is crucial for the improvement of cell replacement therapies for hearing loss. Transcription factor Atoh1 is the key player during HC development and regeneration. In this review, we will focus on Atoh1 and its related signaling pathways (Notch, fibroblast growth factor, and Wnt/β-catenin signaling) involved in the development of cochlear sensory HCs. We will also discuss the potential applicability of these signals for the induction of HC regeneration.

Avaliação eletroacústica da via eferente olivococlear em indivíduos com queixa de zumbido / Electroacoustic evaluation of the olivocochlear efferent pathway in subjects with tinnitus complaint

RESUMO Objetivo: investigar o efeito supressor das emissões otoacústicas por estímulos transientes em indivíduos com queixa zumbido e audiometria normal e analisar sua relação com as variáveis idade, sexo, lateralidade do zumbido e grau de incômodo. Métodos: foram avaliados 60 sujeitos, 14 do gênero masculino e 46 do gênero feminino, entre 20 e 59 anos de idade, sendo 30 com queixa de zumbido (grupo experimental) e 30 sem zumbido (grupo controle). Foi realizada a pesquisa da supressão das emissões otoacústicas por estímulos transientes, para ruído branco de 50 dBNA, na condição contralateral nas bandas de frequência de 700, 1000, 1400, 2000, 2800 and 4000Hz. Resultado: no grupo experimental, a supressão das emissões otoacústicas transientes média variou de 2,14 a 4,38. No grupo controle o valor médio da supressão das emissões otoacústicas transientes variou de 2,27 a 4,88. Conclusão: os valores de supressão das emissões otoacústicas foram semelhantes nos indivíduos com e sem zumbido, embora o grupo com o sintoma tenha tido resultados menores, sugerindo pior desempenho do Complexo Olivar Superior.

ABSTRACT Purpose: to investigate the suppressive effect of transient-evoked otoacoustic emissions in subjects with tinnitus complaint and normal audiometry and to analyze the relation to age, gender, laterality of tinnitus and its degree of discomfort. Methods: we assessed 60 subjects, 14 males and 46 females, aged between 20 and 59 years, 30 with tinnitus (experimental group) and 30 without tinnitus complaint (control group). The suppression of transient-evoked otoacoustic emissions was investigated with contralateral white noise at 50 dBHL at the frequency bands of 700, 1000, 1400, 2000, 2800 and 4000Hz. Results: the mean value for the suppression of transient-evoked otoacoustic emissions in the experimental group ranged from 2.14 to 4.38. In the control group, the mean value for suppression of transient-evoked otoacoustic emissions ranged from 2.27 to 4.88. Conclusion: suppression values of otoacoustic emissions were similar in subjects with and without tinnitus, although the results of the tinnitus group were lower, suggesting worse performance of the Superior Olivary Complex.

Neural-Induced Human Mesenchymal Stem Cells Promote Cochlear Cell Regeneration in Deaf Guinea Pigs

OBJECTIVES: In mammals, cochlear hair cell loss is irreversible and may result in a permanent sensorineural hearing loss. Secondary to this hair cell loss, a progressive loss of spiral ganglion neurons (SGNs) is presented. In this study, we have investigated the effects of neural-induced human mesenchymal stem cells (NI-hMSCs) from human bone marrow on sensory neuronal regeneration from neomycin treated deafened guinea pig cochleae. METHODS: HMSCs were isolated from the bone marrow which was obtained from the mastoid process during mastoidectomy for ear surgery. Following neural induction with basic fibroblast growth factor and forskolin, we studied the several neural marker and performed electrophysiological analysis. NI-hMSCs were transplanted into the neomycin treated deafened guinea pig cochlea. Engraftment of NI-hMSCs was evaluated immunohistologically at 8 weeks after transplantation. RESULTS: Following neural differentiation, hMSCs expressed high levels of neural markers, ionic channel markers, which are important in neural function, and tetrodotoxin-sensitive voltage-dependent sodium currents. After transplantation into the scala tympani of damaged cochlea, NI-hMSCs-injected animals exhibited a significant increase in the number of SGNs compared to Hanks balanced salt solution-injected animals. Transplanted NI-hMSCs were found within the perilymphatic space, the organ of Corti, along the cochlear nerve fibers, and in the spiral ganglion. Furthermore, the grafted NI-hMSCs migrated into the spiral ganglion where they expressed the neuron-specific marker, NeuN. CONCLUSION: The results show the potential of NI-hMSCs to give rise to replace the lost cochlear cells in hearing loss mammals.

Noise-Induced Hearing Loss / 한양의대학술지

Noise-induced hearing loss (NIHL) is the second most common cause of permanent hearing impairment after age-related hearing loss. NIHL is influenced by environmental and genetic factors and the effects of noise can be exacerbated by the administration of ototoxic drugs or exposure to chemicals. The pathophysiology of NIHL is classified as either mechanical injury or metabolic (or biochemical) injury. Exposure of cochleae to intense sounds has been found to disrupt the stereocilia on the hair cells by separating the tip links and to depolymerize actin filaments, resulting in a disturbance in signal transduction. Major mechanisms of metabolic injuries include accumulation of reactive oxygen species enhanced by oxidative stress, cochlear ischemia followed by reperfusion injury, and excitotoxicity to auditory neuron induced by excessive release of the cochlear afferent neurotransmitter, glutamate. Many studies involving therapeutic or preventive trial with antioxidants, JNK inhibitors, and NMDA antagonists have shown partial effectiveness. However, protection from noise before cochlear injury occurs is very important because damaged hair cells and auditory neurons in the mammalian cochleae are unable to regenerate.

Avaliação audiológica em crianças com baixo nível de exposição cumulativa ao chumbo / Audiological evaluation in children with cumulative low-level of lead exposure

Objetivo verificar a ocorrência de perda auditiva sensorioneural em crianças com baixo nível de exposição cumulativa ao chumbo. Métodos 156 crianças intoxicadas por chumbo, 94 do sexo masculino e 62 do sexo feminino, na faixa etária entre 18 meses a 14 anos e 5 meses, foram submetidas a análise longitudinal do nível de Plumbemia em sangue, bem como audiometria tonal liminar e emissões otoacústicas evocadas por estímulo transiente. Resultados a população pesquisada apresentou um valor médio de Plumbemia estimada de 12,2±5,7mg/dL (faixa entre 2,4-33mg/dL); todas as crianças apresentaram resposta normal na audiometria tonal liminar em 20 dBNA nas frequências testadas, 0,5; 1; 2 e 4 kHz, para ambas as orelhas; as emissões otoacústicas evocadas por estímulo transiente estiveram presentes para todas as frequências bilateralmente, nas 79 crianças pesquisadas. Conclusão não foi constatada perda auditiva sensorioneural em crianças com histórico de baixo nível de exposição cumulativa por chumbo, assim como não foi encontrada lesão de células ciliadas externas na cóclea, mesmo que subclínicas. .

Purpose to verify the occurrence of sensorineural hearing loss in children with low level of cumulative lead exposure. Methods 156 lead-poisoned children, 94 males and 62 females, ranging in age from 18 months old to 14 years and 5 months old were subjected to analysis of longitudinal lead level in blood as well as pure tone audiometry and transient evoked otoacoustic emissions. Results the population studied had a mean estimated blood lead level of 12,2±5,7mg/dL (range between 2,4 and 33mg/dL); all children had a normal response in pure tone audiometry at 20 dBHL in the frequencies tested, 0.5, 1, 2 and 4 kHz, in both ears; the transient evoked otoacoustic emissions were presented for all frequencies bilaterally in 79 children surveyed. Conclusion there has been no hearing loss in children with a history of low cumulative lead exposure, as there was no injury of cochlear outer hair cells, even if subclinical. .

Maturação auditiva periférica: análise das amplitudes das emissões otoacústicas produto de distorção em neonatos pré-termo e a termo / Peripheral auditory maturation: analysis of the amplitudes of the distortion product otoacoustic emissions in preterm and term neonates

Objetivo : Comparar neonatos prematuros e a termo quanto à presença e amplitude das Emissões Otoacústicas Produto de Distorção (EOAPD), bem como caracterizá-los em relação aos indicadores de risco para perda auditiva. Métodos : Estudo realizado por análise das EOAPD (frequências de 2000, 3000, 4000, 6000 e 8000 Hz) e dos indicadores de risco para perda auditiva. Os neonatos foram agrupados segundo a idade gestacional. Os resultados foram analisados empregando-se testes ANOVA, Kruskal-Wallis e Qui-quadrado (5%). Resultados : A amostra constituiu-se de 109 neonatos (218 orelhas), com distribuição homogênea quanto ao gênero e a classificação a termo/pré-termo. Foi observado alto risco para perda auditiva em 40,4% dos lactentes. Dos indicadores de risco para deficiência auditiva, os mais frequentes foram a permanência em incubadora e internação em UTI superiores a cinco dias. As EOAPD mostraram-se presentes em 209 orelhas (95,9%). A ausência de respostas às EOAPD foi significativamente mais recorrente nos grupos com menor idade gestacional. Verificou-se aumento das amplitudes das EOAPD de acordo com o aumento da idade gestacional, exceto para a frequência de 8000 Hz na orelha esquerda. Não foi observada diferença entre orelhas e gêneros quanto à presença e amplitude das EOAPD. Conclusão : Há diferença entre os grupos pré-termo e a termo, quanto à presença e amplitude das EOAPD: maior probabilidade de falha nos grupos com menor idade gestacional e aumento (não linear) das amplitudes, conforme a idade gestacional torna-se maior. Os achados sugerem o fenômeno de maturação do sistema auditivo periférico. .

Purpose : To compare preterm and term neonates in relation to the presence and amplitude of Distortion Product Otoacoustic Emissions (DPOAEs), as well as to characterize them regarding risk indicators for hearing loss. Methods : Study realized by the analysis of the DPOAEs (frequencies of 2000, 3000, 4000, 6000 and 8000 Hz) and risk indicators for hearing loss. The neonates were grouped according to the gestational age. The results were analyzed by ANOVA, Kruskal-Wallis and Chi-square tests (5%). Results : The sample consisted of 109 neonates (218 ears) in homogenous distribution related to gender and preterm/term classification. A high risk for hearing loss was observed in 40.4% of the infants. From the risk indicators for hearing loss, the most common were the duration of the stay in incubators and intensive care units (ICU) longer than five days. The DPOAEs were present in 209 ears (95.9%). The absence of responses to DPOEAs was significantly more frequent in groups with lower gestational age. It was observed an increase of the amplitudes of the DPOEAs with the increase of the gestational age, except for the frequency of 8000 Hz in the left ear. There were no differences between ears and genders regarding the presence and amplitude of the DPOAEs. Conclusion : There are differences between preterm and term groups in relation to the presence and amplitude of the DPOAEs: higher probability of failure in the groups with lower gestational age and (nonlinear) increase of the amplitudes with the increase of the gestational age. The findings suggest the phenomenon of maturation of the peripheral auditory system. .

Adipose-derived mesenchymal stem cells differentiate into inner ear hair cells in guinea pigs induced by progressive addition of cytokines / 中国组织工程研究

BACKGROUND:Sensorineural hearing loss is mainly caused by missing or damaged hair cells in the inner ear. Application of adipose-derived mesenchymal stem cells to regenerate inner ear hair cells is an effective treatment for hearing loss. OBJECTIVE:To explore the feasibility of in vitro inducing adipose-derived mesenchymal stem cells to differentiate into inner ear hair cel-like cells in guinea pigs. METHODS:Adipose-derived mesenchymal stem cells from guinea pigs were isolated and cultured to the 3rd generation. cellphenotype was detected using flow cytometry. Cytokines were added for induction and differentiation by stages, including epidermal growth factor, basic fibroblast growth factor, insulin-like growth factor-1, al-trans retinoic acid, brain-derived neurotrophic factor, neurotrophin 3. RESULTS AND CONCLUSION:Adipose-derived mesenchymal stem cells of guinea pigs cultured in vitro were fusiform and showed a swirled adherent growth. Passage 3 cells were positive for CDCD29 and CD44, but negative for CD34 and CD45. After induction, the cells were positive for nestin and GFAP positive at early stage;after 10-day continuous induction, the cells expressed Myosin VIIa and Math1, specific markers of hair cells, indicating that cytokines can directly induce adipose-derived mesenchymal stem cells to differentiating into inner ear hair cells in guinea pigs.

Crianças com fenilcetonúria: avaliação audiológica básica e supressão das otoemissões / Children with phenylketonuria: basic audiological evaluation and suppression of otoacoustic emissions

OBJETIVO: Avaliar a via auditiva de crianças com fenilcetonúria tratadas precocemente, por meio de audiometria, imitanciometria e supressão das emissões otoacústicas transientes. MÉTODOS:Estudo prospectivo transversal comparativo com amostra composta por 28 crianças, sendo 12 com fenilcetonúria e 16 sem a doença. Foi realizada a pesquisa dos limiares de audibilidade por via aérea e óssea, logoaudiometria, imitanciometria e supressão das emissões otoacústicas transientes. RESULTADOS: A audiometria e a logoaudiometria estiveram normais em todos os participantes. Foram encontrados piores resultados para o índice de reconhecimento de fala (IRF) no grupo com fenilcetonúria. A imitanciometria revelou curva normal para todas as crianças, mas a pesquisa dos reflexos estapedianos demonstrou que as crianças do grupo com fenilcetonúria apresentaram aumento nos seus limiares nas frequências de 2 e 4 kHz. A supressão das emissões otoacústicas transientes não revelou diferença na comparação entre os grupos. CONCLUSÃO: A avaliação audiológica básica não identifica alterações na audição das crianças com fenilcetonúria, mas há pior discriminação ao IRF e aumento nos limiares de reflexos estapedianos nessas crianças, podendo indicar distúrbios do processamento auditivo. O estudo da supressão das otoemissões demonstra integridade do sistema eferente olivococlear medial nas crianças com fenilcetonúria.

PURPOSE: To evaluate the auditory pathways of children with early-treated phenylketonuria through audiometry, immitance tests, and suppression of transient otoacoustic emissions. METHODS: Prospective cross-sectional study with sample composed by 28 children: 12 with phenylketonuria and 16 without the disease. Participants underwent auditory evaluations composed of air- and bone-conduction pure-tone audiometry, speech audiometry, immittance tests and suppression of transient otoacoustic emissions. RESULTS: All participants presented normal results in pure-tone and speech audiometry; however, speech discrimination scores were lower on the phenylketonuria group. Immitance tests revealed normal tympanograms for all children, but stapedial reflex thresholds demonstrated higher thresholds in 2 and 4 kHz for children with phenylketonuria. The suppresion of transient otoacoustic emissions did not show difference in the comparison between groups. CONCLUSION: The basic audiologic assessment do not identify hearing disorders in children with phenylketonuria; however, speech discrimination scores were lower and stapedial reflexes were higher in these children, which may indicate auditory processing disorders. The study of the suppression of transient otoacoustic emissions demonstrated integrity of the olivocochlear efferent system in children with phenylketonuria.