Efficient Bone Conduction Hearing Device With a Novel Piezoelectric Transducer Using Skin as an Electrode.

Objective: Bone conduction hearing aids are the only non-surgical devices used for conductive hearing loss. However, they are impractical for lifelong use since they require close contact of the transducer with the head skin, causing skin erosion and discomfort. Bone conduction hearing implants and active middle ear implants do not present these issues; however, they require surgery and can sometimes cause issues in the skin surrounding the devices.

Neck and superior mediastinal granular cell tumor excised via a combined approach.

Granular cell tumor (GCT) is an uncommon tumor of Schwann cell origin. GCT occurs in various sites throughout the body, but mediastinal GCT is very rare. We present an extremely rare case of GCT of the neck and superior mediastinum.

[A case of metastatic salivary duct carcinoma successfully treated with trastuzumab-based targeted therapy].

Salivary duct carcinoma is a malignant salivary neoplasm with a poor prognosis. Effective treatment for remote metastases has not been recognized. We report herein on a case of this tumor overexpressing HER2 successfully treated with trastuzumab-based molecular targeted therapy.

[Successful treatment of dysphagia due to Wallenberg syndrome using intermittent air stretching method with balloon catheter: a case report].

A 69-year-old woman presented with dysphagia due to Wallenberg syndrome. Videofluorography revealed unilateral dysfunction of the cricopharyngeal muscle, which caused stenosis of the esophageal entrance on the affected side. Pharyngeal fiberscopy indicated that glottal function and the cough reflex were preserved and that the pharyngeal reflex was lost.

Afferent deprivation elicits a transcriptional response associated with neuronal survival after a critical period in the mouse cochlear nucleus.

The mechanisms underlying enhanced plasticity of synaptic connections and susceptibilities to manipulations of afferent activity in developing sensory systems are not well understood. One example is the rapid and dramatic neuron death that occurs after removal of afferent input to the cochlear nucleus (CN) of young mammals and birds. The molecular basis of this critical period of neuronal vulnerability and the transition to survival independent of afferent input remains to be defined.

Destiny of autologous bone marrow-derived stromal cells implanted in the vocal fold.

Objectives: The aim of this study was to investigate the destiny of implanted autologous bone marrow-derived stromal cells (BSCs) containing mesenchymal stem cells. We previously reported the successful regeneration of an injured vocal fold through implantation of BSCs in a canine model. However, the fate of the implanted BSCs was not examined.

A new method for drug application to the inner ear.

Inner ear sensory cells are very susceptible to injuries and recovery after damage is very difficult. Recently several drugs including neurotrophic factors have been reported to protect against inner ear injury. The purpose of this experimental study is to find new methods for applying drugs to the inner ear that effectively protect against inner ear damage.

Novel strategy for treatment of inner ears using a biodegradable gel.

Objective: The present study aimed to evaluate the efficacy of a biodegradable hydrogel as a drug-delivery medium for the inner ear. Brain-derived neurotrophic factor (BDNF) was chosen as the agent to be administered.

Method: First, we used an enzyme-linked immunosorbent assay to measure BDNF concentrations in the cochlear fluid after placing a hydrogel containing this agent onto the round-window membrane of the ear.

Engraftment of embryonic stem cell-derived neurons into the cochlear modiolus.

This study aimed to evaluate the potential of embryonic stem cell-derived neural progenitors for use as transplants for the replacement of the auditory primary neurons, spiral ganglion neurons. Mouse embryonic stem cell-derived neural progenitors were implanted into the base of the cochlear modiolus of normal or deafened guinea pigs, which contains spiral ganglion neurons and cochlear nerve fibers. Histological analysis demonstrated the survival and neural differentiation of transplants in the cochlear modiolus and active neurite outgrowth of transplants toward host peripheral or central auditory systems.

Disruption and restoration of cell-cell junctions in mouse vestibular epithelia following aminoglycoside treatment.

The intracellular junction complexes, which consist of tight junctions (TJ), adherens junctions (AJ), and desmosomes, mediate cell-cell adhesion in epithelial cells. E-cadherin, which is a major component of AJ, plays a role not only in the maintenance of cell-cell junctions, but also in repressing cell proliferation. In this study, we examined changes of E-cadherin expression in mouse vestibular epithelia following local application of neomycin using immunohistochemistry and western blotting, and morphology of cell-cell junctions by transmission electron microscopy (TEM).

Nuclear translocation of beta-catenin in developing auditory epithelia of mice.

Beta-catenin, a protein component of adherens junctions, plays a role in the signalling pathway for cell proliferation. In this study, we examined the cellular distribution of beta-catenin in developing auditory epithelia of mice. Immunohistochemistry for Ki67 and cyclin D indicated active cell proliferation in premature auditory epithelia.

Role of reactive radicals in degeneration of the auditory system of mice following cisplatin treatment.

Objective: It has been suggested that reactive radical species are involved in the mechanism of cisplatin-induced hearing loss. However, the nature of the free radicals involved is not fully understood. We examined the effects of two highly reactive species, hydroxyl radicals and peroxynitrite, on the auditory system of mice following cisplatin treatment.

Aging effects on vestibulo-ocular responses in C57BL/6 mice: comparison with alteration in auditory function.

Age-related changes in auditory function are well documented in animal models; however, this is not the case as regards vestibular function. In this study, we evaluated age-related changes in vestibulo-ocular responses in C57BL/6 mice that are considered as a model of presbycusis. The functional data were substantiated by the findings of histological analysis of vestibular and auditory peripherals.

Elevation of superoxide dismutase increases acoustic trauma from noise exposure.

The generation of superoxide has been implicated as a cause of cochlear damage from excessive noise. Cu/Zn superoxide dismutase (SOD1) generally will protect against superoxide-mediated tissue injury but protection by this enzyme against noise trauma is controversial. This study assessed auditory function in C57BL/6 mice overexpressing SOD1 or treated with lecithinized SOD1 (PC-SOD1).

Mechanisms of apoptosis induced by cisplatin in marginal cells in mouse stria vascularis.

Degeneration of the stria vascularis (SV) is amongst the major causes of cisplatin (CDDP)-induced hearing impairment. The pathways of apoptosis occurring in the SV due to CDDP were examined using a mouse experimental model. Temporal bones of adult C57BL/6 mice were collected on days 3, 7 and 14 after the local application of CDDP.

Transplantation of bone marrow stromal cells into the cochlea of chinchillas.

This study aimed to evaluate the potential of bone marrow stromal cells for treatment of inner ear diseases. Autologous marrow cells labeled with Dil were implanted into the inner ear of five gentamicin-treated chinchillas. Histological analysis 3 weeks later revealed robust survival of grafted marrow cells in multiple regions within the cochlea.

Signaling pathway for apoptosis of vestibular hair cells of mice due to aminoglycosides.

Previous studies on regeneration of mammalian vestibular hair cells have indicated the potential for self-repair of damaged hair cells. The rescue of damaged hair cells from cell death may therefore increase regenerated hair cells in affected vestibular epithelia. The role of apoptosis in the degradation of vestibular hair cells following aminoglycoside treatment has been elucidated.

Transplantation of neural stem cells into the modiolus of mouse cochleae injured by cisplatin.

This study aimed to examine the possibility of restoration of spiral ganglion neurons, which transmit sound stimulation to the brain, by transplantation of fetal neural stem cells (NSCs) into the modiolus of cochleae. Fetal mouse NSCs expressing green fluorescence were injected into the modiolus of cisplatin-treated cochleae of mice. The temporal bones were collected 14 days after transplantation, and provided histological examination.

Fates of mouse embryonic stem cells transplanted into the inner ears of adult mice and embryonic chickens.

The potential of embryonic stem (ES) cells to differentiate into inner ear hair cells was examined in this study. Undifferentiated mouse ES cells transplanted into neomycin-damaged mouse inner ears were evaluated by immunohistochemistry 4 weeks after transplantation. Some ES cells were positive for E-cadherin or NCAM, and most transplanted cells were positive for SSEA3 and Ki67.

Surgical techniques for cell transplantation into the mouse cochlea.

This study investigated surgical procedures for cell transplantation into the mouse inner ear. Female C57BL/6 mice were used as recipient animals. Fetal mouse neural stem cells expressing green fluorescence were used as donor cells.

Induction of cell proliferation and beta-catenin expression in rat utricles in vitro.

Limited regenerative response occurs in mammalian vestibular epithelia, although vestibular hair cell regeneration in mammals has been demonstrated under a variety of experimental conditions. Beta-catenin is known to play an important role in both cell-cell adhesion and signal transduction associated with cell proliferation. This study evaluated cell proliferation activity in mammalian vestibular epithelia in organotypic culture and examined the involvement of beta-catenin in cell proliferation in vestibular epithelia.

Expression of beta-catenin in developing auditory epithelia of mice.

This study investigated the role of beta-catenin in the development of mouse auditory epithelia. Inner ears obtained from embryonic and newborn mice were used. Expression of beta-catenin was examined together with the expression of Ki-67, a marker for proliferating cells, or myosin VIIa, a marker for differentiated hair cells.

Fate of neural stem cells grafted into injured inner ears of mice.

Loss of sensory hair cells in the inner ear is a major cause of permanent hearing loss, since regeneration of hair cells rarely occurs in mammals. The aim of this study was to examine the potential of neural stem cell transplantation to restore inner ear hair cells in mice. Fetal neural stem cells were transplanted into the mouse inner ear after drug-induced injury.

A novel model for rapid induction of apoptosis in spiral ganglions of mice.

Objectives/hypothesis: The survival of the spiral ganglion (SG) is a critical issue in preservation of hearing. Research on topics related to this issue requires a mouse experimental model because such a model has advantages including use of genetic information and knockout or "knockin" mice. Thus, the aim of the study was to establish a mouse model for induction of apoptosis of SG neurons with a definite time course.

Role of the F-box protein Skp2 in cell proliferation in the developing auditory system in mice.

The F-box protein, Skp2 positively regulates the G1-S transition by controlling the stability of several G1 regulators, including p27. To evaluate the role of Skp2 in the mammalian developing auditory systems, the expression of Skp2 was examined together with the expression of p27 in auditory systems. Our data show expression of Skp2 in auditory epithelia and neurons at an early stage of development.