Microscopic Versus Endoscopic Ear Surgery for Early-Stage Glomus Tympanicum Tumors.

Purpose: Glomus tympanicum tumors are benign primary tumors of the middle ear that can be completely removed using modern surgery. We compared endoscopic ear surgery (EES) to traditional microscopic ear surgery (MES) in terms of the removal of early-stage glomus tympanicum tumors. Methods: We retrospectively reviewed 25 cases treated from 2003 to 2021 that were of Grade I or II based on the Glasscock-Jackson classification system. Overall, 18 cases underwent MES: 8 via trans-tympanic bone and 10 via canal-wall-down or canal-wall-up tympanomastoidectomy (CWDT or CWUT) and 7 underwent EES. We compared surgery durations, the lengths and costs of hospitalization, postoperative complications, and relapse rates between the two groups and among the three specific operation ways. Results: The postoperative follow-up period ranged from 1 to 19 years. There was no between-group difference in operative time or the length or cost of hospitalization. Operative time and cost of hospitalization did not show a statistically significant correlation to the three surgical procedures, whereas it was found that the group of MES via the trans-tympanic bone had shorter length of hospitalization when compared with CWUT or CWDT group. All tumors were completely resected; pulsatile tinnitus improved in all patients, and there was no major complication. Two patients who underwent CWUT or CWDT (one each) relapsed; no patient relapsed in the EES group. Conclusion: MES via the trans-tympanic bone and EES via the ear canal safely and reliably remove early-stage tumors without excessive patient discomfort.

Key Genes and Endoscopic Radical Surgery in Primary Middle Ear Oncocytic Papillomas.

OBJECTIVE: Papillomas originating from the Schneiderian epithelium within the middle ear are extremely rare and may be associated with a high rate of recurrence and malignant transformation. Oncocytic papillomas represent the rarest pathological subtype of such tumors. The current investigation aimed to determine whether there exists a distinct mechanism underlying the incidence of oncocytic papillomas arising primarily within the middle ear, and to explore potential treatment strategies to ensure complete removal and prevent recurrence. STUDY DESIGN: Search of the English literature for cases of middle ear papilloma and RNA sequencing analysis of three samples from one new case presenting at the Eye and ENT Hospital, Fudan University (Shanghai, China), with recurrent middle ear oncocytic papilloma, along with two normal mucosal samples. SETTING: Academic, tertiary referral hospital. PATIENT AND INTERVENTIONS: The patient underwent open mastoidectomy and endoscopic tympanoplasty twice in 6 years. Histopathology confirmed oncocytic papilloma in middle ear. The patient has been free of the disease at 18 months of follow-up without radiation, whereas the RNA-seq analysis of the samples in endoscopic operations remained nonmalignant. RESULTS: Only four cases of primary middle ear oncocytic papillomas have been reported. Recurrent masses usually originate from around the eustachian tube, which may explain the pathogenesis of this lesion. RNA-seq analysis was used to identify 1,317 (UP, 239; DOWN, 1078) differentially expressed genes between papillomas and normal mucosa. The involvement of some hub proteins (e.g., FN1, CXCL8, L10, JUN, and FOS) in the pathogenesis of primary middle ear papillomas was found to align with the observed clinical features. CONCLUSION: The middle ear oncocytic papillomas were extremely rare and remained incompletely understood. The findings of this first RNA-seq analysis of this rare tumor may serve to enhance comprehension of and aid in the management of middle ear papillomas.

Full Endoscopic Resection of Intralabyrinthine Schwannomas: A Case Series.

Objective: To investigate the technique and efficacy of fully endoscope resection of intralabyrinthine schwannomas (ILS) by transcanal transpromontorial endoscopic approach (TTEA). Study Design: Retrospective case review. Setting: Hospital. Patients: All patients who were affected by ILS, without extension to the internal auditory canal and underwent surgery with TTEA in our hospital in 2020. Intervention(s): Therapeutic. Main Outcome Measure(s): Recovery status, postoperative complications and remaining symptoms after surgery. Results: Three patients were included, all of which underwent gross total resections. The follow-up period was from 10 months to 2 years. No intraoperative and postoperative major complications were observed. There was no facial paralysis or cerebrospinal fluid leakage postoperatively. The hospitalization time of TTEA was 5 days. Three patients' vertigo was relieved after 1 week without receiving vestibular therapy. Only 1 patient complained of transient episodes of vertigo when climbing or holding heavy objects. Conclusions: TTEA has the advantages of clear vision to identify the anatomical structure, enabling complete tumor resection, reduced operation time, and faster postoperative recovery.Level of Evidence: IV.

The co-pyrolysis of waste urea-formaldehyde resin with pine sawdust: co-pyrolysis behavior, pyrocarbon and its adsorption performance for Cr (VI).

Urea-formaldehyde (UF) resin is difficult to degrade and classified as hazardous organic waste. To address this concern, the co-pyrolysis behavior of UF resin with pine sawdust (PS) was studied, and the adsorption properties of pyrocarbon were evaluated with Cr (VI). Thermogravimetric analysis revealed that adding a small amount of PS can improve the pyrolysis behavior of UF resin. Based on the Flynn Wall Ozawa (FWO) method, the kinetics and activation energy values were estimated. It was observed that when the amount of UF resin exceeded twice that of PS, the activation energy of the reaction decreased, and they acted synergistically. The characterization of pyrocarbon samples showed that the specific surface area increased with the increase of temperature, while the content of functional groups showed the opposite trend. Intermittent adsorption experiments showed that 5UF + PS400 achieved 95% removal of 50 mg/L Cr (VI) at 0.6 g/L dosage and at pH 2. The adsorption process was consistent with the Langmuir isotherm and pseudo-second-order kinetics, and the maximum adsorption was 143.66 mg/g at 30 ℃. Furthermore, the adsorption process consisted of electrostatic adsorption, chelation, and redox reaction. Overall, this study provides a useful reference for the co-pyrolysis of UF resin and the adsorption capacity of pyrocarbon.

The transcriptome characteristics of vestibular organs from delayed endolymphatic hydrops patients (Meniere's disease).

OBJECTIVES: To identify genes that are related to delayed endolymphatic hydrops (DEH) in patients by RNA-Seq analysis. DESIGN: Observational study. SETTING: Eye & ENT Hospital, Fudan University (Shanghai, China). PARTICIPANTS: We collected the entire vestibular system from four patients with DEH who underwent labyrinthectomy. Three control samples were collected from patients with acoustic neuroma or facial neuroma treated via the translabyrinthine approach. High-throughput RNA-Seq analysis was performed to investigate gene expression in the pathological vestibular system. MAIN OUTCOME MEASURES: Our bioinformatic analysis identified 17 genes that were upregulated and eight genes that were downregulated in patients with DEH compared with the controls. RESULTS: The altered gene expression profile suggested that DEH is closely related to neuropathy and autoimmune disease. In addition, many of the differentially regulated genes were involved in cell adhesion, suggesting a role of cell adhesion in DEH. Immunofluorescence analysis confirmed the expression of PMP2 and CLDN19 in the cytoplasm of hair cells and scattered expression of MPZ at cell junctions. The protein expression levels were higher in specimens from patients with Ménière's disease and DEH compared with controls. CONCLUSIONS: The protein expression profile of vestibular organs in patients with endolymphatic hydrops exhibited a degree of similarity to that of Ménière's disease. Endolymphatic hydrops is characterised by autoimmune abnormalities. DEH and Ménière's disease are likely to be different manifestations of the same disease, with disparate clinical symptoms. RNA-Seq is a useful analytical tool to characterise the vestibular pathology based on its transcriptome.

Planar cell polarity governs the alignment of the nasopharyngeal epithelium in mammals.

Planar cell polarity (PCP) signalling specifies the orientation of epithelial cells and regulates directional beating of motile cilia of multiciliated epithelial cells. Clinically, defects in cilia function are associated with nasopharyngeal symptoms. The polarity of the nasopharyngeal epithelium is poorly understood. Here, we demonstrated PCP in the nasopharyngeal epithelium. Multiciliated cells (MCCs) were uniformly aligned with their long axis parallel to the tissue axis of the nasopharynx (NP). In addition, PCP proteins exhibited an asymmetrical localisation between adjacent cells. Motile cilia were uniformly aligned in the same direction within both individual cells and neighbouring cells, which manifested as cilial polarity in MCCs. Mutation of Vangl2, a mammalian homologue of the Drosophila PCP gene, resulted in significant disruption of the orientation of epithelial cells. Finally, keratin-5-positive basal cells constantly replenished the luminal ciliated cells; the new dynamic ciliated cells were also oriented parallel to the tissue axis. These results indicate a role for the PCP pathway in the uniform orientation of dynamically replenished epithelial cells in the NP.

Myringoplasty With an Ultrathin Cartilage-Perichondrium Complex Graft Versus Temporalis Fascia Graft: A Propensity Score-Matched Analysis.

OBJECTIVE: To compare endoscopic myringoplasty using the cartilage-perichondrium complex as a graft (test group) with temporalis fascia microscopic myringoplasty (control group). STUDY DESIGN: A retrospective cohort study. SETTING: Department of Otorhinolaryngology in a tertiary Chinese hospital. METHODS: Data were collected on patients between 2017 and 2019. To balance the baseline characteristics between groups, we performed a propensity score-matched analysis, and 44 patients were included in each group. Hearing improvement and eardrum closure rates were compared, and risk factors affecting them were analyzed. RESULTS: In the control and test groups, 90.90% and 86.36% of patients had a mean air-bone gap ≤20 dB after the surgery, respectively (P = .843). The air conduction (AC) threshold gain at each frequency was similar in the 2 groups (P > .05). The closure rates were 95.45% and 93.18%, respectively (P = .645). The air-bone gap improved significantly after surgery, F(1, 61) = 6.729, P = .012. Age, group, middle ear mucosal status, and location of the perforation did not affect the change in air-bone gap or the drum closure rate (P > .05). However, there was an interaction between the change in air-bone gap and the size of the perforation, F(1, 61) = 11.067, P = 0001. CONCLUSION: Endoscopic myringoplasty using a cartilage-perichondrium complex graft is comparable with traditional surgery. Age, location of the perforation, and middle ear mucosal status did not significantly affect the change in air-bone gap or the drum closure rate. A perforation size ≥50% was always associated with a better air-bone gap improvement.

The microbiomes of adenoid and middle ear in children with otitis media with effusion and hypertrophy from a tertiary hospital in China.

INTRODUCTION: Otitis media with effusion (OME) is one of the most common pediatric diseases worldwide. Several studies have analyzed the diversity of the microbiomes found in the middle ear effusions (MEEs) of populations from developed countries. However, no microbiological studies of MEEs from Chinese children with OME have been reported. This study investigated the middle ear and adenoid microbiological profiles of children with OME, and compared the microbial flora of the adenoid between children with and without otitis media. METHODS: MEEs and adenoid swabs were acquired from 15 children undergoing ventilation tube insertion and adenoidectomy. Adenoid swabs from 15 patients with no ear disease were used as controls. Samples were analyzed by 16S rRNA sequencing. Operational taxonomic units (OTUs) abundance information were normalized. Alpha diversity analyses were used to assess the richness and diversity of the microbial community for each sample. Beta diversity analyses were used to determine the inter-group variability between microbiome structure. RESULTS: Based on the mean relative abundance, the MEEs were dominated by Haemophilus (14.75%), Staphylococcus (9.37%) and Halomonas (7.85%), and the bacterial compositions of the adenoids in the OME groups were dominated by Haemophilus (21.87%), Streptococcus (19.65%), and Neisseria (5.8%). The bacterial compositions in the adenoids of the controls were dominated by Haemophilus (15.96%), Streptococcus (13.33%), and Moraxella (12.28%). Alpha diversity analyses showed that there were no significant differences in microbiome richness or diversity between the middle ear effusions (TM) and adenoids (TA) of OME subjects. Adenoid samples from OME patients (TA) and control patients (CA) were also similar. Beta diversity analyses showed that the microbiomes of the adenoids in OME patients were also similar to that of controls. However, the microbiome structure of middle ear effusions was dissimilar to those of the adenoids in OME patients according to beta diversity analyses. CONCLUSIONS: Our results confirmed the microbial diversity of MEEs among Chinese children. However, the dissimilar microbiome composition between samples taken from the surface of the adenoids and from the middle ear effusions challenges the conventional theory that the adenoid serves as a microbial reservoir in children with otitis media with effusion.

Concurrent Occurrence of Congenital Ossicular Anomaly and Localized Cholesteatoma: Series of 10 Cases.

OBJECTIVE: The objective of this study is to describe the clinical features, managements and outcomes of a rare coexistence of congenital ossicular anomaly and localized cholesteatoma. A literature review on these cases and each congenital disorder is also presented. METHODS: A retrospective chart review was performed on patients diagnosed with congenital ossicular anomaly with concurrent localized cholesteatoma from 2008 to 2017. Clinical data of these patients were collected. RESULTS: A total of 10 patients were identified. All patients presented with unilateral hearing loss. Pure-tone audiometry showed conductive hearing loss in all affected ears with an average air conduction (AC) threshold of 59 dB. High-resolution computed tomography scans of the temporal bone diagnosed ossicular anomaly for 90% (9/10); however, only 50% (5/10) had a diagnosis of localized cholesteatoma. A transcanal exploratory tympanotomy under the microscope was performed to discover whether the localized tiny-sized cholesteatoma around the ossicular chain did not have direct contact with the ossicular chain, which could be diagnosed as congenital cholesteatoma. We removed the localized cholesteatoma and reconstructed the ossicular chain in each patient. All localized cholesteatomas were found in the posterior-superior quadrant of the middle ear. Ossicular chain anomalies were associated with the incus and/or the stapes in all cases. Hearing improvement was achieved in each of the 6 patients who were followed up postoperatively, with an average AC threshold of 35 dB. The clinical features of congenital ossicular anomaly with concurrent congenital cholesteatoma were compared with those of each congenital disorder. The pathogenesis of each condition was also discussed. CONCLUSIONS: Congenital ossicular anomaly with concurrent congenital cholesteatoma is rare. It shares similar clinical features with congenital ossicular anomaly occurring alone, therefore awareness should be raised for a possible concurrent congenital cholesteatoma which was easy to miss in the diagnosis (50%) by the radiologist. A patient's hearing level can be improved by removal of the cholesteatoma and reconstruction of the ossicular chain. Localized cholesteatoma does not usually show residuals or recurrence.

The Atoh1 expression levels are correlated with the arrangement, ciliary morphology, and electrophysiological characteristics of ectopic hair cell-like cells.

Previous reports have suggested that the level and duration of Atoh1 expression are correlated with the survival, arrangement and stereociliary bundle-related morphology of hair cells during development, but whether Atoh1 expression levels are correlated with the arrangement, bundle formation and electrophysiological characteristics of newly formed hair cells is unknown. To address this question, cultured cochlear explants obtained from neonatal rats were treated with different titers of a human adenovirus serotype 5 (Ad5) vector encoding Atoh1 and/or EGFP (EGFP-Atoh1+/-). The results showed that higher EGFP-Atoh1 concentrations led to higher initial Atoh1 mRNA expression levels and induced greater numbers of ectopic hair cell-like cells (EHCLCs) in the lesser epithelial ridge (LER). Furthermore, gradual increases in the number of EHCLCs were associated with the progressive conversion of the LER region similarly to that of hair cells during development. Some of the cilia on EHCLCs with higher Atoh1 expression were regularly arranged in a manner similar to that of normal hair bundles. As demonstrated through patch clamp recordings, high Atoh1 expression was associated with significantly decreased proportions of cells with Ih currents, significantly reduced proportions of transient potassium channel currents, and potassium channel currents with a greatly increased mean amplitude, which indicated that EHCLCs with high Atoh1 expression were more mature than those with low Atoh1 expression. Overall, the evidence suggests that the Atoh1 expression levels affect not only the arrangement and ciliary morphology of hair cells but also the electrophysiological characteristics of Atoh1-induced EHCLCs, and these findings provide important guidance for future therapies aimed at treating deafness.

Deep Learning in Automated Region Proposal and Diagnosis of Chronic Otitis Media Based on Computed Tomography.

OBJECTIVES: The purpose of this study was to develop a deep-learning framework for the diagnosis of chronic otitis media (COM) based on temporal bone computed tomography (CT) scans. DESIGN: A total of 562 COM patients with 672 temporal bone CT scans of both ears were included. The final dataset consisted of 1147 ears, and each of them was assigned with a ground truth label from one of the 3 conditions: normal, chronic suppurative otitis media, and cholesteatoma. A random selection of 85% dataset (n = 975) was used for training and validation. The framework contained two deep-learning networks with distinct functions: a region proposal network for extracting regions of interest from 2-dimensional CT slices; and a classification network for diagnosis of COM based on the extracted regions. The performance of this framework was evaluated on the remaining 15% dataset (n = 172) and compared with that of 6 clinical experts who read the same CT images only. The panel included 2 otologists, 3 otolaryngologists, and 1 radiologist. RESULTS: The area under the receiver operating characteristic curve of the artificial intelligence model in classifying COM versus normal was 0.92, with sensitivity (83.3%) and specificity (91.4%) exceeding the averages of clinical experts (81.1% and 88.8%, respectively). In a 3-class classification task, this network had higher overall accuracy (76.7% versus 73.8%), higher recall rates in identifying chronic suppurative otitis media (75% versus 70%) and cholesteatoma (76% versus 53%) cases, and superior consistency in duplicated cases (100% versus 81%) compared with clinical experts. CONCLUSIONS: This article presented a deep-learning framework that automatically extracted the region of interest from two-dimensional temporal bone CT slices and made diagnosis of COM. The performance of this model was comparable and, in some cases, superior to that of clinical experts. These results implied a promising prospect for clinical application of artificial intelligence in the diagnosis of COM based on CT images.

The Role of the Notch Signal Pathway in Mucosal Cell Metaplasia in Mouse Acute Otitis Media.

Otitis media (OM) is a major cause of morbidity in pediatric and adult patients. This inflammatory condition is characterized by mucous cell hyperplasia that is thought to produce mucins from the middle ear mucosa. We are interested in the role of Notch signalling pathway in this inflammatory process. Using an acute otitis media (AOM) mouse model through injection of Streptococcus Pneumoniae into the middle ear, histopathologic examination and quantitative RT-PCR, acute inflammation with the thickness of mucosa, Goblet cell hyperplasia, and cilia loss were determined and gene expression related to the Notch signaling pathway were evaluated. Upregulation of the mucous cell markers, Argr2 and Muc5AC, and downregulation of the cilia cell marker, Foxj1 and Dnai2, were observed in AOM. In addition, genes encoding Notch receptors and ligands (Notch1, Notch2, Notch3, Notch4 and Dll1) and the Notch target genes (Hes1, Hes5, Hey1, NRARP) in AOM decreased significantly. The expression of the Notch1 and Jagged1 also showed down-regulation throughout the mouse middle ear epithelium. Taken together, this study suggests that downregulation of the Notch signaling pathway is involved in the mucosa hyperplasia during AOM.

Afferent synaptogenesis between ectopic hair-cell-like cells and neurites of spiral ganglion induced by Atoh1 in mammals in vitro.

Newly formed ectopic hair-cell-like cells (EHCLCs) induced by overexpression of atonal homolog 1 (Atoh1) in vitro were found to possess features of endogenous hair cells (HCs) in previous reports and in the present study. However, limited information is available regarding whether EHCLCs and native spiral ganglion neurons (SGNs) form afferent synapses, which are important for the restoration of hearing. In the current study, we focused on the afferent synaptogenesis between EHCLCs and SGN-derived dendrites. Cochlear explants of auditory epithelia with native SGNs retained were cultured in vitro, and human adenovirus serotype 5 (Ad5) vectors encoding Atoh1 were used to overexpress Atoh1 and induce EHCLCs. We observed that the neurites of the original SGNs extended toward the lesser epithelial ridge (LER) and innervated the EHCLCs. Immunohistochemical analyses revealed the expression of presynaptic ribbon C-terminal-binding protein 2 (CtBP2) and postsynaptic density protein (PSD)-95 in the nerve endings of SGN-derived neurons adjacent to EHCLCs. PSD-95 was located directly opposite CtBP2-positive puncta in the terminals of branches of SGNs, demonstrating that the neurites of SGNs formed afferent-like synaptic connections with EHCLCs. However, the expression of glutamate receptor type 2 (GluR2) could not be detected in the terminals of branches of SGNs surrounding EHCLCs. In addition, we found that the presynaptic ribbon (CtBP2) formation in EHCLCs preceded neural innervation. Furthermore, CtBP2-positive puncta increased and then decreased in EHCLCs, similar to the changes observed in endogenous HCs in terms of their number and distribution. Our finding of the generation of cochlear afferent synapses between EHCLCs and original SGNs will lay the foundation for regenerative approaches to restoring hearing after hair cell loss.

Cilia distribution and polarity in the epithelial lining of the mouse middle ear cavity.

The middle ear conducts sound to the cochlea for hearing. Otitis media (OM) is the most common illness in childhood. Moreover, chronic OM with effusion (COME) is the leading cause of conductive hearing loss. Clinically, COME is highly associated with Primary Ciliary Dyskinesia, implicating significant contributions of cilia dysfunction to COME. The understanding of middle ear cilia properties that are critical to OM susceptibility, however, is limited. Here, we confirmed the presence of a ciliated region near the Eustachian tube orifice at the ventral region of the middle ear cavity, consisting mostly of a lumen layer of multi-ciliated and a layer of Keratin-5-positive basal cells. We also found that the motile cilia are polarized coordinately and display a planar cell polarity. Surprisingly, we also found a region of multi-ciliated cells that line the posterior dorsal pole of the middle ear cavity which was previously thought to contain only non-ciliated cells. Our study provided a more complete understanding of cilia distribution and revealed for the first time coordinated polarity of cilia in the epithelium of the mammalian middle ear, thus illustrating novel structural features that are likely critical for middle ear functions and related to OM susceptibility.

Notch pathway inhibitor DAPT enhances Atoh1 activity to generate new hair cells in situ in rat cochleae.

Atoh1 overexpression in cochlear epithelium induces new hair cell formation. Use of adenovirus-mediated Atoh1 overexpression has mainly focused on the rat lesser epithelial ridge and induces ectopic hair cell regeneration. The sensory region of rat cochlea is difficult to transfect, thus new hair cells are rarely produced in situ in rat cochlear explants. After culturing rat cochleae in medium containing 10% fetal bovine serum, adenovirus successfully infected the sensory region as the width of the supporting cell area was significantly increased. Adenovirus encoding Atoh1 infected the sensory region and induced hair cell formation in situ. Combined application of the Notch inhibitor DAPT and Atoh1 increased the Atoh1 expression level and decreased hes1 and hes5 levels, further promoting hair cell generation. Our results demonstrate that DAPT enhances Atoh1 activity to promote hair cell regeneration in rat cochlear sensory epithelium in vitro.

Notch signaling is active in normal mouse middle ear epithelial cells.

Mucous cell metaplasia/hyperplasia in the middle ear epithelium is associated with the occurrence of otitis media with effusion during infections. However, the mechanism by which Notch signaling regulates cell fate in the middle ear epithelium is unclear. The aim of the present study was to elucidate this mechanism by investigating the localization of Notch receptors, such as Notch1 and Notch2, and Notch ligands, such as Jagged1, in the normal mouse middle ear epithelium (NMMEE) using immunofluorescence. Furthermore, the mRNA expression levels of Notch receptors and ligands were evaluated using reverse transcription polymerase chain reaction (PCR). The effects of the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine tert-butyl ester (DAPT) on epithelial cell proliferation were determined using 5-ethynyl-2'-deoxyuridine (EdU) staining and immunofluorescence staining of the apoptosis marker caspase-3 and the epithelial proliferation marker pan-cytokeratine. In addition, the differentiation of the NMMEE cells was characterized by evaluating the mRNA expression levels of the mucous cell-associated genes Arg2, Muc2, Spdef, Spink4 and Tff1 using quantitative PCR. Notch1, Notch2 and Jagged1 were observed to be co-localized throughout the mouse middle ear epithelium. Furthermore, Notch1-4, Jagged1, Jagged2, Dll1 and Dll4 mRNAs were expressed in the NMMEE cells. The inhibition of Notch by DAPT resulted in fewer EdU-positive cells and the upregulation of the expression levels of various mucous cell-associated genes. The results indicate that DAPT suppresses the proliferation of NMMEE cells while promoting their differentiation into mucous cells. Therefore, DAPT may provide a specific therapeutic strategy for the reversal of multiple pathological processes that are associated with epithelium thickening in the middle ear.

Analysis of the Damage Mechanism Related to CO2 Laser Cochleostomy on Guinea Pig Cochlea.

Different types of lasers have been used in inner ear surgery. Therefore, it is of the utmost importance to avoid damage to the inner ear (e.g., hyperthermia and acoustic effects) caused by the use of such lasers. The aim of this study was to use a high powered fibre-enabled CO2 laser (10 W, 606 J/cm2) to perform cochleostomies on guinea pig cochlea and to investigate the possible laser-induced damage mechanisms. The temperature changes in the round window membrane, auditory evoked brainstem response, and morphological of the hair cells were measured and recorded before and after laser application. All of the outcomes differed in comparison with the control group. A rise in temperature and subsequent increased hearing loss were observed in animals that underwent surgery with a 10 W CO2 laser. These findings correlated with increased injury to the cochlear ultrastructure and a higher positive expression of E-cadherin and ß-catenin in the damaged organ of Corti. We assume that enhanced cell-cell adhesion and the activated ß-catenin-related canonical Wnt-signalling pathway may play a role in the protection of the cochlea to prevent further damage.

Role of the planar cell polarity pathway in regulating ectopic hair cell-like cells induced by Math1 and testosterone treatment.

Planar cell polarity (PCP) signaling regulates cochlear extension and coordinates orientation of sensory hair cells in the inner ear. Retroviral-mediated introduction of the Math1 transcription factor leads to the transdifferentiation of some mature supporting cells into hair cells. Testosterone, a gonadal sex steroid hormone, is associated with neuroprotection and regeneration in Central Nervous System (CNS) development. Experiments were performed in vitro using Ad5-EGFP-Math1/Ad5-Math1 in neonatal mouse cochleas. Establishment of ectopic hair-cell like cell(HCLC) polarity in the lesser epithelial ridge (LER) with or without testosterone-3-(O-carboxymethyl) oxime bovine serum albumin (testosterone-BSA) treatment was investigated to determine the role of the PCP pathway in regulating ectopic regenerated (HCLCs) through induction by Math1 and testosterone treatment. After Math1 infection, new ectopic regenerated HCLCs were detected in the LER. After the HCLCs developed actin-rich stereocilia, the basal bodies moved from the center to the distal side. Moreover, the narrower, non-sensory LER region meant that the convergent extension (CE) was also established after transfection with Math1. After 9 days of in vitro testosterone-BSA treatment, more Edu(+), Sox2(+), and HCLC cells were observed in the LER with an accompanying downregulation of E-cadherin. Interestingly, the CE of the Ad5-EGFP-math1 treated LER is altered, but the intrinsic cellular polarity of the HCLCs is not obviously changed. In summary, our results indicate that PCP signaling is involved in the development of ectopic HCLCs and the CE of the ectopic sensory region is altered by testosterone-BSA through downregulation of cell-cell adhesion. Testosterone-BSA and Math1 treatment could promote an increase in HCLCs in the LER through proliferation and transdifferentiation.

Changes in ADF/destrin expression in the development of hair cells following Atoh1-induced ectopic regeneration.

The aim of this study was to investigate the effects of actin depolymerizing factor (ADF)/destrin and position changes of kinetosomes in the development of hair cells following Atoh1-induced ectopic regeneration in the basilar membrane of mice. We observed through immunofluorescence at various time-points the expression of ADF/destrin and the specific kinetosome marker, γ-tubulin, in hair cells following ectopic regeneration induced by adenovirus transfection, overexpression of Atoh1 and in vitro culture. Changes of ADF/destrin distribution and kinetosome position during in vitro culture of new hair cells [Myo7a(+)] following Atoh1-induced ectopic regeneration are consistent with the changes in ADF/destrin expression and the polar migration of kinetosomes in hair cells of the cochlear sensory epithelium in normal development. ADF/destrin is involved in the development of the auditory epithelium and the development and structural rearrangement of ectopically regenerated hair cells in mammals. The kinetosomes of hair cells following Atoh1-induced ectopic regeneration show positional changes in vitro at different time-points.