Beneficial effects of time-restricted feeding on gentamicin cytotoxicity in mouse cochlea and vestibular organs.

Objective: Time restricted feeding (TRF), which is an intermittent fasting protocol, has been reported to decrease the toxicity and mortality rate associated with systemic gentamicin (GM) administration. The aim of this study is to evaluate the effect of TRF on GM-induced vestibular and auditory function in mice. Methods: Japan Central Laboratory for Experimental Animals:Institute of Cancer Research (Jcl:ICR) mice were housed in a light-dark (LD) cycle (12:12) and were divided into three groups: (1) GM treatment at a dose of 220 mg/kg with TRF (feeding time: 8 h [9:00-17:00] during the light phase [7:00-19:00]) (GM + TRF group), (2) GM treatment at a dose of 220 mg/kg without TRF (GM group), and (3) saline injection with TRF (NS + TRF group). GM or saline was injected subcutaneously for 18 days (three courses of 5 days' injection + 2 days' rest, and an additional 3 days' injection). The auditory brainstem response (ABR) and vestibular evoked potential (VsEP) were tested after the treatments. The number of sensory hair cells in the cochlear organs and the vestibular organs were quantified using microscopic images. Results: All animals survived until the end of the experiment. One day after the last injection, GM + TRF mice showed significantly lower ABR thresholds at 4 kHz compared to GM mice, and there was no significant difference between the GM + TRF and NS + TRF groups. There was a significant difference of VsEP between GM and GM + TRF mice only in symmetric parabolic waves with linear acceleration and ramps waveform stimulation. GM + TRF mice showed significantly less outer and inner hair cell loss compared to GM mice. GM + TRF mice showed significantly less type II hair cell loss in the utricle and the ampulla compared to GM mice. Conclusion: TRF with daytime feeding reduced GM cytotoxicity in the cochlea and vestibular organs of ICR mice. Level of Evidence: NA.

Alteration of Vestibular Function in Pediatric Cochlear Implant Recipients.

Background: Vestibular dysfunction is a complication of cochlear implantation (CI). Reports on the evaluation of vestibular function before and after CI are limited, especially in children. We investigated the effect of CI on vestibular function in pediatric patients. Patients and Methods: We routinely evaluated vestibular function before but not immediately after CI. Therefore, patients who underwent sequential bilateral CI were enrolled in this study. Seventy-three children who underwent sequential CI from 2003 to 2020 at our hospital were included. Since the vestibular function of the first implanted ear was evaluated before the second surgery for the contralateral ear, post-CI evaluation timing differed among the cases. The evaluation included a caloric test, a cervical vestibular-evoked myogenic potential (cVEMP) test, and a damped rotation test. The objective variables included the results of these tests, and the explanatory variables included the age at surgery, cause of hearing loss, electrode type, and surgical approach used. The associations of these tests were analyzed. Results: cVEMP was the most affected after CI (36.1%), followed by the caloric test (23.6%), and damped rotation test (7.8%). Cochleostomy was significantly more harmful than a round window (RW) approach or an extended RW approach based on the results of the caloric test (p = 0.035) and damped rotation test (p = 0.029). Perimodiolar electrodes affected the caloric test results greater than straight electrodes (p = 0.041). There were no significant associations among these tests' results. Conclusions: Minimally invasive surgery in children using a round window approach or an extended round window approach with straight electrodes is desirable to preserve vestibular function after CI.

Caloric restriction reduces basal cell proliferation and results in the deterioration of neuroepithelial regeneration following olfactotoxic mucosal damage in mouse olfactory mucosa.

The effects of caloric restriction (CR) on cell dynamics and gene expression in the mouse olfactory neuroepithelium are evaluated. Eight-week-old male C57BL/6 mice were fed either control pellets (104 kcal/week) or CR pellets (67 kcal/week). The cytoarchitecture of the olfactory neuroepithelium in the uninjured condition and its regeneration after injury by an olfactotoxic chemical, methimazole, were compared between mice fed with the control and CR diets. In the uninjured condition, there were significantly fewer olfactory marker protein (OMP)-positive olfactory receptor neurons and Ki67-positive proliferating basal cells at 3 months in the CR group than in the control group. The number of Ki67-positive basal cells increased after methimazole-induced mucosal injury in both the control and the CR groups, but the increase was less robust in the CR group. The recovery of the neuroepithelium at 2 months after methimazole administration was less complete in the CR group than in the control group. These histological changes were region-specific. The decrease in the OMP-positive neurons was prominent in the anterior region of the olfactory mucosa. Gene expression analysis using a DNA microarray and quantitative real-time polymerase chain reaction demonstrated that the expression levels of two inflammatory cytokines, interleukin-6 and chemokine ligand 1, were elevated in the olfactory mucosa of the CR group compared with the control group. These findings suggest that CR may be disadvantageous to the maintenance of the olfactory neuroepithelium, especially when it is injured.

Macrophage recruitment, but not interleukin 1 beta activation, enhances noise-induced hearing damage.

It has been suggested that macrophages or inflammatory monocytes participate in the pathology of noise-induced hearing loss (NIHL), but it is unclear how extensively these cells contribute to the development of temporary and/or permanent NIHL. To address this question, we used clodronate liposomes to deplete macrophages and monocytes. After clodronate liposome injection, mice were exposed to 4-kHz octave band noise at 121 dB for 4 h. Compared to vehicle-injected controls, clodronate-treated mice exhibited significantly reduced permanent threshold shifts at 4 and 8 kHz and significantly smaller outer hair cell losses in the lower-apical cochlear turn. Following noise exposure, the stria vascularis had significantly more cells expressing the macrophage-specific protein F4/80, and this effect was significantly suppressed by clodronate treatment. These F4/80-positive cells expressed interleukin 1 beta (IL-1ß), which noise exposure activated. However, IL-1ß deficient mice did not exhibit significant resistance to intense noise when compared to wild-type mice. These findings suggest that macrophages that enter the cochlea after noise exposure are involved in NIHL, whereas IL-1ß inhibition does not reverse this cochlear damage. Therefore, macrophages may be a promising therapeutic target in human sensorineural hearing losses such as NIHL.

Denervation of nasal mucosa induced by posterior nasal neurectomy suppresses nasal secretion, not hypersensitivity, in an allergic rhinitis rat model.

The posterior nasal nerve is the dominant source of the parasympathetic, sympathetic, and sensory fibers that innervate the nasal respiratory mucosa. Therefore, a posterior nasal neurectomy (PNN) is thought to induce denervation of the nasal mucosa and relieve the nasal symptoms of allergic rhinitis. However, the underlying mechanisms and therapeutic action of PNN remain unknown. To investigate the impact of PNN-induced denervation of the nasal mucosa on allergic rhinitis, we developed a rat model of PNN and examined the effects of PNN on allergic rhinitis in ovalbumin-sensitized rats. This rat model of PNN was characterized by the depletion of nerve fibers, choline acetyltransferase, and neuropeptides (eg, substance P, calcitonin gene-related peptide, vasoactive intestinal peptide, and neuropeptide Y) in the nasal respiratory mucosa. These animals exhibited nasal gland and goblet cell hypertrophy in the septal mucosa and atrophy of the submucosal gland in the lateral nasal wall, as well as reduced nasal secretion due to deficient acetylcholine synthesis. In an ovalbumin-sensitized model of allergic rhinitis, PNN also induced the depletion of nerve fibers, choline acetyltransferase, and neuropeptides in the nasal mucosa and suppressed nasal secretion. However, PNN did not affect mucosal thickening, eosinophil and mast cell infiltration, interleukin-4 and interferon-γ mRNA expression, and allergic symptoms (ie, sneezing and nasal scratching). These results suggest that the peripheral nerves and corresponding neuropeptides regulate nasal secretion, but not hypersensitivity, in allergic rhinitis, and that allergic rhinitis-related mucosal reactions occur in a highly denervated mucosa after PNN. Posterior nasal neurectomy may be a therapeutic option for the treatment of hyperrhinorrhea, but not allergic rhinitis hypersensitivity.

Association of the upregulated expression of focal adhesion kinase with poor prognosis and tumor dissemination in hypopharyngeal cancer.

BACKGROUND: Focal adhesion kinase (FAK) plays an important role in tumor metastasis. The purpose of this study was to evaluate the significance of FAK expression in surgically treated patients with hypopharyngeal cancer. METHODS: We retrospectively reviewed the clinical charts of patients treated at our institution between 2004 and 2012 and identified 87 patients with hypopharyngeal cancer. FAK expression status was retrospectively evaluated using immunohistochemistry. RESULTS: FAK-positive patients displayed significantly worse disease-specific survival than FAK-negative patients (p = .001). Multivariate analyses revealed that FAK positivity and extracapsular spread (ECS) were independent, significant adverse prognostic factors. Furthermore, FAK positivity significantly correlated with the number of metastatic lymph nodes (p = .048), and FAK-positive patients displayed a higher incidence of distant metastases (p = .009). CONCLUSION: The current study demonstrated that upregulated FAK expression correlates with poor prognosis and tumor dissemination in surgically treated patients with hypopharyngeal cancer. © 2016 Wiley Periodicals, Inc. Head Neck 38:1164-1169, 2016.

Human Papillomavirus 16 Physical Status and the TP53 Codon 72 Polymorphism in Japanese HPV-Positive Oropharyngeal Cancer Patients.

BACKGROUND: In human papillomavirus (HPV)-induced carcinogenesis, the arginine (Arg) allele of the TP53 codon 72 polymorphism binds more efficiently to the HPV E6 oncoprotein than the proline (Pro) allele. We investigated the physical status of HPV-16 DNA and the TP53 codon 72 polymorphism in oropharyngeal squamous cell carcinoma (OPSCC). METHODS: Tumor samples from 70 p16-positive OPSCC patients were tested for HPV-16 physical status by examining the E2 and E6 open reading frames. The TP53 codon 72 polymorphism was screened by direct sequencing. RESULTS: Of 70 patients, 53 were E6 positive, 29 had integrated forms of HPV-16 DNA, and 24 had mixed or episomal forms. Furthermore, 44 carried the Arg/Arg or Arg/Pro genotype, 3 carried the Pro/Pro genotype, and in 6 patients we were unable to obtain sequencing data. CONCLUSIONS: HPV-16 physical status was heterogeneous in our OPSCC patients. Most OPSCC patients had the TP53 Arg/Arg or Arg/Pro genotype.

Prognostic value of p16 expression irrespective of human papillomavirus status in patients with oropharyngeal carcinoma.

OBJECTIVE: In a previous study, we reported the value of p16 expression and alcohol consumption in oropharyngeal carcinoma in Japan. We now report the clinical significance of human papillomavirus status and p16 expression in oropharyngeal carcinoma in Japan. METHODS: Over a 9-year period, a retrospective case comparison study of the pathology database was conducted at the University of Tokyo to identify tumor samples of oropharyngeal carcinoma. We performed immunohistochemistry for the p16 protein, in situ hybridization for human papillomavirus-deoxyribonucleic acid and polymerase chain reaction for the human papillomavirus-deoxyribonucleic acid oncogene E6 in oropharyngeal carcinoma in Japanese patients. We evaluated the human papillomavirus status in patients with oropharyngeal carcinoma to determine its prevalence and association with prognosis. We defined human papillomavirus(+) and human papillomavirus(-) oropharyngeal carcinoma cohorts as those with and without polymerase chain reaction for the human papillomavirus-deoxyribonucleic acid oncogene E6 or in situ hybridization-human papillomavirus. RESULTS: In oropharyngeal carcinoma, the prevalences of p16(+)human papillomavirus(+), p16(+)human papillomavirus(-), p16(-)human papillomavirus(+) and p16(-)human papillomavirus(-) were 32% (48/150), 7% (10/150), 2% (3/150) and 59% (89/150), respectively. Low tobacco and alcohol consumption, tonsil or base of tongue localization, but not age, were associated with p16(+)human papillomavirus(+). Low alcohol consumption was associated with p16(+)human papillomavirus(-). There was a significant difference in overall survival between p16(+)human papillomavirus(-) and p16(-)human papillomavirus(-) (P = 0.03). In multivariate Cox regression models, p16 was the independent prognostic factor, regardless of human papillomavirus status. CONCLUSION: p16 expression was a reliable prognostic biomarker regardless of human papillomavirus status.

Maxillary carcinosarcoma: Identification of a novel MET mutation in both carcinomatous and sarcomatous components through next generation sequencing.

BACKGROUND: Carcinosarcoma is a rare tumor with biphasic growth of the carcinomatous and sarcomatous components. Prognosis is generally poor and characterization of the molecular mechanisms may provide information for the development of novel antitumor agents and biomarkers. METHODS AND RESULTS: We present the case of 66-year-old man with a complaint of nasal obstruction. He was diagnosed with maxillary carcinosarcoma and coexisting papilloma. He underwent multimodal treatment but died of uncontrolled local disease 10 months after the initial presentation. Genetic testing using next-generation sequencing (NGS) revealed that both the carcinomatous and sarcomatous components carried a somatic mutation in the conserved domain of the mesenchymal-epithelial transition factor (MET) proto-oncogene. CONCLUSION: Our observation highlighted the importance of the MET gene in the oncogenesis of maxillary carcinosarcoma and is indicative of the common clonal origin of both malignant components. This suggested a possibility of treating MET mutation-positive carcinosarcomas with c-MET inhibitors.

Idiopathic latent vestibulopathy: a clinical entity as a cause of chronic postural instability.

The objective of this study is to describe a new clinical entity of idiopathic latent vestibulopathy (ILV), in which patients have unilateral or bilateral vestibulopathy combined with unsteadiness but without episodic vertigo, auditory disturbance, or a medical history suggesting the presence of vestibulopathy. A retrospective study of 1,233 consecutive new outpatients was conducted. Two-legged stance tasks were performed by 11 patients identified as having ILV in four conditions: eyes open with and without foam rubber, and eyes closed with and without foam rubber. We examined six parameters: the velocity of movement of the center of pressure (COP) with eyes closed/foam rubber, the envelopment area traced by the movement of the COP with eyes closed/foam rubber, Romberg's ratio of velocity and area with foam rubber, and the foam ratios of velocity and area with eyes closed. Multiple regression analyses were performed in order to explore the relationship between the presence of ILV and the six parameters recorded during foam posturography, while adjusting for the subjects' gender and age. The presence of ILV had a significantly positive relationship with the values of 4 of the 6 parameters. Even though six patients showed only unilateral vestibulopathy, their median value in all 6 parameters was greater than that of healthy controls. ILV could be a clinical entity accountable for postural instability.

Ocular vestibular evoked myogenic potentials in response to air-conducted sound and bone-conducted vibration in vestibular schwannoma.

OBJECTIVE: To clarify the origin and pathways of ocular vestibular evoked myogenic potentials (oVEMPs) to air-conducted sound (ACS), we compared the results of oVEMPs with ACS, with oVEMPs with bone-conducted vibration (BCV), cervical VEMPs (cVEMPs) with ACS, and the caloric test in patients with unilateral vestibular schwannoma (VS). STUDY DESIGN: Retrospective review. SETTING: Tertiary referral center. PATIENTS: Forty-five patients with untreated unilateral VS. MAIN OUTCOME MEASURE: Each patient underwent vestibular tests, including oVEMPs to ACS, oVEMPs to BCV, cVEMPs to ACS, and caloric tests. The correlations among these tests were evaluated. RESULTS: Of the 45 patients recruited, 28 patients (63%) showed reduced or absent oVEMPs to ACS solely on the affected side. There were no significant differences in abnormal response ratios among oVEMPs to ACS, oVEMPs to BCV, cVEMPs to ACS, or the caloric test. The results of oVEMPs to ACS had a significant correlation with those of oVEMPs to BCV and the caloric test (p < 0.05) but not with those of cVEMPs to ACS (p > 0.05). CONCLUSION: These findings support the hypothesis that oVEMP in response to ACS are predominantly mediated by the superior vestibular nerve and probably reflect the function of the utricle.

Factors affecting postural instability in Meniere's disease.

OBJECTIVE: To assess the influence of factors that can affect the postural instability of Ménière's disease (MD) patients. STUDY DESIGN: Case-control study. SETTING: Outpatient clinic in a university hospital. SUBJECTS AND METHODS: Fifty-four definite MD patients and 66 controls were included. Two-legged stance tasks were performed in 4 conditions: eyes open with and without foam rubber and eyes closed with and without foam rubber. We examined 6 variables: the velocity of movement of the center of pressure (COP), the envelopment area traced by the movement of the COP, Romberg's ratio of velocity and area, and the foam ratios of velocity and area. For patients, stepwise multiple regression analyses were performed to explore the relationship between the 6 variables and the following independent variables: gender, age, the presence of abnormal caloric and/or cervical vestibular evoked myogenic potential (cVEMP) responses, the time elapsed since the last vertigo attack, and the disease duration. RESULTS: The presence of MD had a significantly positive relationship with all 6 of the variables (P < .05). The presence of abnormal caloric and/or cVEMP responses had a significantly positive relationship with Romberg's ratio of velocity (P < .05) and area (P < .01). The shorter time interval from last vertigo attack to measurement had a significantly positive relationship with the foam ratio of area (P < .01). CONCLUSION: MD patients show poor postural performance, which is affected by the existence of their peripheral vestibular function and the shorter time interval from last vertigo attack to measurement.

Effect of vestibular dysfunction on the development of gross motor function in children with profound hearing loss.

OBJECTIVE: To evaluate the function of the superior and inferior vestibular nerve systems in children with profound sensorineural hearing loss, and to assess the influence of dysfunction of each vestibular nerve system on the development of gross motor function. STUDY DESIGN: Retrospective study. SETTING: A tertiary referral center. METHODS: Eighty-nine children (age range: 20-97 months) with profound sensorineural hearing loss who were due to undergo cochlear implant surgery were recruited. Function of the superior vestibular nerve system was evaluated by the damped rotation test and the caloric test, whereas functions of the inferior vestibular nerve systems were evaluated by the vestibular evoked myogenic potential (VEMP) test. Gross motor development was assessed using the age of acquisition of head control and independent walking. RESULTS: Among the children able to complete the vestibular function tests, abnormalities were found in 20% (16 of 84 children) in the damped rotation test, 41% (31 of 75 children) in the caloric test and 42% (26 of 62 children) in the VEMP test. Children who showed abnormal responses in the vestibular function tests showed significantly delayed acquisition of head control (p < 0.05) and independent walking (p < 0.05) in comparison with children with normal responses. The children who showed abnormal responses in all 3 vestibular tests showed the greatest delay in acquisition of gross motor function in comparison with the other groups. CONCLUSIONS: Children with profound hearing loss tend to have dysfunction in the superior as well as the inferior vestibular nerve systems. Both the superior and inferior vestibular nerve systems are important for the development of gross motor function in children.

The diagnostic value of vestibular-evoked myogenic potential in patients with vestibular schwannoma.

OBJECTIVE: This study examined the diagnostic value of the vestibular-evoked myogenic potential (VEMP) in comparison with the caloric test in patients with vestibular schwannoma (VS). METHODS: Data were retrospectively collected from 803 consecutive patients who visited our vertigo clinic and underwent vestibular tests. Amongst them, 78 patients were diagnosed as having untreated unilateral VS. VEMP was performed using click and short-tone burst stimulation. The caloric test was performed using ice water. The sensitivity and specificity of each test were evaluated. RESULTS: Of the 78 patients with VS, 63 had abnormal VEMPs as well as abnormal caloric responses. Of the 725 patients without VS, 382 had normal VEMPs and 416 had normal caloric responses. The sensitivity and specificity of VEMP were 80.8% (95% CI: 72.0-89.5%) and 52.7% (95% CI: 49.1-56.3%), respectively; those of the caloric test were 80.8% (95% CI: 72.0-89.5%) and 57.4% (95% CI: 53.8-61.0%), respectively. CONCLUSIONS: The sensitivity and specificity of VEMP and the caloric test showed no significant differences. SIGNIFICANCE: In patients with VS, although the specificity of VEMP was not very high, its sensitivity was high and comparable to that of the caloric test.

Reversible impairment of auditory callosal pathway in 5-fluorouracil-induced leukoencephalopathy: parallel changes in function and imaging.

OBJECTIVE: To report the course of functional and imaging recovery of the auditory callosal pathway in a patient with 5-fluorouracil-induced leukoencephalopathy. DESIGN: Case study. SETTING: University hospital. PATIENT: A 58-year-old man with hypopharyngeal cancer who developed 5-fluorouracil-induced leukoencephalopathy. MAIN OUTCOME MEASURES: Imaging (magnetic resonance imaging) and functional (dichotic listening test) evaluation on the auditory callosal pathway. RESULTS: The patient underwent systemic chemotherapy with pirarubicin, cisplatin, and 5-fluorouracil. On the last day of the regimen, the patient suddenly became restless and convulsive. On diffusion-weighted magnetic resonance images, the signal intensity at the splenium of the corpus callosum was very high. Fluid-attenuated inversion recovery images showed no abnormal findings at this time. Intravenous methylprednisolone sodium succinate and glycerin 10% was started immediately. On the ninth day after onset, the patient was free of neurologic symptoms. Although pure-tone audiograms and speech discrimination scores were normal, dichotic listening tests revealed significant left ear suppression, indicating severe injury of the auditory callosal pathway. On fluid-attenuated inversion recovery images, the signal intensity at the splenium was high, whereas the posterior trunk was normal. At 6 weeks after onset, dichotic listening test results returned to normal and hyperintensity at the splenium was much less marked on fluid-attenuated inversion recovery images. CONCLUSION: By using both functional and imaging modalities, this case study demonstrated, for the first time in a reversible manner, that the auditory callosal pathway runs through the most posterior part of the corpus callosum including the splenium. Diffusion-weighted magnetic resonance imaging was considered useful for early diagnosis of 5-fluorouracil-induced leukoencephalopathy.