• Biomedical Science Letters
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• v.29 no.3
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• pp.95-102
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• 2023

The inner ear constitutes a complex organ responsible for auditory perception and equilibrium. It comprises diverse cellular entities operating collaboratively to perceive and transmit sensory information to the brain. Inner ear disease is a sophisticated and multifactorial scenario substantially impacting the quality of life of affected individuals. Gaining insights into the developmental process of the inner ear is crucial for diagnosing and treating inner ear diseases, which can lead to hearing loss and impaired balance. Recent research in inner ear development and associated pathophysiology has focused on several pivotal domains, including identifying new genes and signaling pathways involved in inner ear development, using stem cells for inner ear regeneration, and developing novel therapies for inner ear diseases. Recent advances in genetics research have shed new light on the fundamental etiologies of inner ear diseases, with a growing body of evidence suggesting that genetic mutations might exert a pivotal influence on the development and progression of this condition. In this review, we have delved into certain common genetic mutations linked to inner ear disorders. We also discussed ongoing research endeavors and future directions for understanding the genetic mechanisms underlying this condition and potential therapeutic avenues.

• Molecules and Cells
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• v.41 no.7
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• pp.695-702
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• 2018

The inner ear is a complex sensory organ responsible for hearing and balance. Formation of the inner ear is dependent on tight regulation of spatial and temporal expression of genes that direct a series of developmental processes. Recently, epigenetic regulation has emerged as a crucial regulator of the development of various organs. However, what roles higher-order chromatin organization and its regulator molecules play in inner ear development are unclear. CCCTC-binding factor (CTCF) is a highly conserved 11-zinc finger protein that regulates the three-dimensional architecture of chromatin, and is involved in various gene regulation processes. To delineate the role of CTCF in inner ear development, the present study investigated inner ear-specific Ctcf knockout mouse embryos (Pax2-Cre; $Ctcf^{fl/fl}$). The loss of Ctcf resulted in multiple defects of inner ear development and severely compromised otic neurogenesis, which was partly due to a loss of Neurog1 expression. Furthermore, reduced Neurog1 gene expression by CTCF knockdown was found to be associated with changes in histone modification at the gene's promoter, as well as its upstream enhancer. The results of the present study demonstrate that CTCF plays an essential role in otic neurogenesis by modulating histone modification in the Neurog1 locus.

• BMB Reports
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• v.50 no.10
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• pp.487-495
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• 2017

Mammalian inner ear comprises of six sensory organs; cochlea, utricle, saccule, and three semicircular canals. The cochlea contains sensory epithelium known as the organ of Corti which senses sound through mechanosensory hair cells. Mammalian inner ear undergoes series of morphogenesis during development beginning thickening of ectoderm nearby hindbrain. These events require tight regulation of multiple signaling cascades including FGF, Wnt, Notch and Bmp signaling. In this review, we will discuss the role of newly emerging signaling, FGF signaling, for its roles required for cochlear development.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.193-198
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• 2022

Contrast enhanced magnetic resonance imaging using gadolinium-based contrast agent (GBCA) is a very useful in vivo technique to visualize the inner ear pathology including endolymphatic hydrops. Although systemic intravenous (IV) administration can visualize the perilymph space, the visualization was possible by indirect passage of contrast agent through blood-perilymph barrier. All animal experimental procedures were performed under anesthesia with 5% isoflurane. Lipopolysaccharide (LPS) was instilled into the left tympanic cavity through the tympanic membrane using a sterile 27gauge needle to induce hydrops model. Tucker-Davis Technologies system was used to measure Auditory Brainstem Responses (ABRs). For intracerebroven-tricular (ICV) administration, 25 µmol of GADOVIST (Bayer, Berlin, Germany) was used and diluted GADOVIST injection was 10 µl. MR imaging was acquired with a 9.4 Tesla MRI scanner. Transmit-receive volume coil with 40 mm inner diameter and 75 mm out diameter was used. ICV administration well demonstrated the strong enhancement along the cerebrospinal fluid (CSF) microcirculation pathway including CSF fluid in the subarachnoid space and CSF space of the inner ear structures. On the other hand, IV administration showed no contrast enhancement along the CSF microcirculation pathway and showed weak enhancement in the inner ear structures. In case of rat hydrops model, ICV administration showed that the reduced contrast enhancement in the perilymph space of the hydrops induced inner ear compared to the contrast enhancement in the perilymph space of the normal inner ear. New systemic ICV administration method provide contrast enhancement of GBCA in the inner ear through CSF microcirculation pathway.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.535-544
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• 1996

In this paper, we analyzed the coil-magnet type vibrating transducer for the implantable middle ear hearing aid which is appropriate for patient's hearing level, and an experimental transducer system is designed For the objective and quantitative analysis of the transducer, a theoretical equivalent model containing coil, magneto and inner ear is developed To perform effective evaluation of the transducer, a transforming ratio Tr is introduced and its range that is suitable for practical implantable middle ear hearing device is foun4 The result of applying physical parameters of ear system to the proposed analytical model shows that frequency response of the coil magrlet type vibrator is predominantly governed by resistive impedance of the coil rather than inertia effect of the magnet and the inner parameters. In addition, we realized an experimental middle ear hearing aid system to show the theoretical validity of designed system and this will provide the basis of the development for actually implantable system.

• Korean Journal of Computational Design and Engineering
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• v.14 no.2
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• pp.87-95
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• 2009

This paper describes the design of the ossicular replacement prosthesis for the people who have problem of hearing because of middle ear disease. Also the simulation results of the designed product for verification by finite element analysis software (ABAQUS) are presented. New model is applied to middle ear FE analysis which was generated in previous study. The full replacements of ossicular prosthesis for ossicles (malleus, incus and stapes) are made of Hydroxyapatite and Titanium. Although other existing prosthesis models consider only sound amplification effect, current type has damper system which is operating on the audible frequencies. High frequency sound transmitted to inner ear can be reduced and the prosthesis and inner ear can be prevented from damage.

• Journal of Sensor Science and Technology
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• v.24 no.6
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• pp.373-378
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• 2015

The structure of the human ear is divided into the outer ear, the middle ear, and the inner ear. The inner ear includes the cochlea that plays a very important role in hearing. Recently, the development of an artificial cochlear device for the hearing impaired with cochlear damage has been actively researched. Research has been carried out on the biomimetic piezoelectric thin film ABM (Artificial Basilar Membrane) in particular. In an effort to improve the frequency separation performance of the existing piezoelectric thin film ABM, this paper presents the design, fabrication, and characterization of the production and performance of a partially etched-type ABM material. $O_2$ plasma etching equipment was used to partially etch a piezoelectric thin film ABM to make it more flexible. The mechanical-behavior characterization of the manufactured partially etched-type ABM showed that the overall separation frequency range shifted to a lower frequency range more suitable for audible frequency bandwidths and it displayed an improved frequency separation performance. In addition, the maximum magnitude of the vibration displacement at the first local resonant frequency was enhanced by three times from 38 nm to 112 nm. It is expected that the newly designed, partially etched-type ABM will improve the issue of cross-talk between nearby electrodes and that the manufactured partially etched-type ABM will be utilized for next-generation ABM research.

• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.74-77
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• 2011

We report a novel extension of 840 nm wavelength- based spectral domain optical tomography to in vivo/real-time human middle ear diagnosis. The system was designed to access the middle ear region with a specifically dedicated handheld probe. The real-time displaying feature was mandatory for in vivo imaging human subject with the handheld probe, and the system could provide about 20 frames per second for 2048 pixels by 1000 A-scans without using any graphics process units under the Labview platform. The inner ear structure of a healthy male volunteer was imaged with the developed system with the axial and lateral resolutions of $15\;{\mu}m$ and $30\;{\mu}m$, respectively. The application of the OCT technology to early diagnose otitis media(OM) is very promising and could be another extensive branch in the OCT field because it provides the depth resolved image including tympanic membrane (TM) and structures below TM whereas the conventional otoscope technique only gives asurface image of the TM.

• Development and Reproduction
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• v.23 no.2
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• pp.171-181
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• 2019

To produce healthy and stable seed production, we need to obtain information and understand vision that affects behavior of red spotted grouper. We examined their expression and retinal development during the juvenile development. Short-wavelength sensitive opsin (SWS2), a cone photoreceptor, began to be expressed from lens and ear vesicle formation stage and its expression increased until 10 days after hatching (dah). In case of middle-wavelength sensitive opsin (MWS), its expression was detected at 3 dah and reached the highest level at 21 dah. The expression of long-wavelength sensitive opsin (LWS) was first observed from 3 dah and their expression decreased thereafter. Rhodopsin, a rod photoreceptor, was found to be expressed from 2 dah and its expression reached the highest level at 50 dah. The outer nuclear layer (ONL), inner nuclear layer (INL) and ganglion cell layer began to differentiate at 2 dah, while choroid first appeared at 4 dah so that the eyes became black. These results indicate that the development of retina mostly completes around 4 dah. It seems that the development of the retina and the expression of the opsin genes are closely related to the behavior such as hunting prey, considering that the timing of the completion of the development of the retina, the timing of gene expression, and the timing of completion of yolk absorption are similar.

• BMB Reports
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• v.41 no.5
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• pp.345-352
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• 2008

The cerebral microvessels possess barrier characteristics which are tightly sealed excluding many toxic substances and protecting neural tissues. The specialized blood-neural barriers as well as the cerebral microvascular barrier are recognized in the retina, inner ear, spinal cord, and cerebrospinal fluid. Microvascular endothelial cells in the brain closely interact with other components such as astrocytes, pericytes, perivascular microglia and neurons to form functional 'neurovascular unit'. Communication between endothelial cells and other surrounding cells enhances the barrier functions, consequently resulting in maintenance and elaboration of proper brain homeostasis. Furthermore, the disruption of the neurovascular unit is closely involved in cerebrovascular disorders. In this review, we focus on the location and function of these various blood-neural barriers, and the importance of the cell-to-cell communication for development and maintenance of the barrier integrity at the neurovascular unit. We also demonstrate the close relation between the alteration of the blood-neural barriers and cerebrovascular disorders.