Determining Invasion Depth in Superficial Pharyngeal Carcinoma by Transoral Ultrasonography

OBJECTIVES

To examine the clinical usefulness of transoral ultrasonography (US) in determining the invasion depth of superficial pharyngeal carcinoma (SPC). Determining the invasion depth of SPC is crucial for transoral surgery including determining treatment strategy. This study aimed to examine the usefulness of transoral US in determining the invasion depth of SPC.

METHODS

Forty-six patients with 51 lesions who underwent both magnifying endoscopy with narrow-band imaging (ME-NBI) and transoral US were included. The primary outcomes were the sensitivity, specificity, positive (PPV), and negative predictive values (NPV) of ME-NBI and transoral US findings for pathological tumor depth in SPCs.

RESULTS

The accuracy (82.4%), sensitivity (85.2%), PPV (82.1%), and NPV (82.6%) rates of US for subepithelial propria (SEP) were higher than those of ME-NBI and macroscopic classification, indicating that transoral US is superior to ME-NBI in determining the invasion depth. All cases where the SEP was clearly invaded (SEP deep) could be diagnosed as SEP by transoral US.

CONCLUSIONS

Transoral US may be useful in determining the invasion depth of SPCs.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:2192-2197, 2023.

A 14-year nationwide epidemiological analysis of delayed endolymphatic hydrops in Japan

BACKGROUND

Delayed endolymphatic hydrops (DEH) is an inner ear disease that causes recurrent vertigo in the ipsilateral ear or fluctuating hearing in the contralateral ear due to endolymphatic hydrops secondary to preceding deafness. There are few reports of large, multicentre studies investigating the clinical-epidemiological characteristics of DEH.

OBJECTIVE

This study aimed to clarify the characteristics of DEH in Japan.

METHODS

Clinical data on 662 patients with DEH were analysed by nationwide, multicentre surveys conducted by the Peripheral Vestibular Disorders Research Group of Japan.

RESULTS

The proportion of ipsilateral DEH (IDEH) was slightly higher than that of contralateral DEH (CDEH) at 55.4%. The time delay between onset of precedent deafness and onset of DEH was significantly longer for CDEH than for IDEH. The most common cause of precedent deafness was a disease of unknown cause with onset in early childhood (33.1%). Epidemiological characteristics were not significantly different between CDEH with and without vertigo.

CONCLUSION

DEH appearing to be caused by viral labyrinthitis has a high rate of onset within 40 years of precedent deafness. Clinical and epidemiological characteristics of IDEH, CDEH with vertigo, and CDEH without vertigo were very similar.

SIGNIFICANCE

The clinical-epidemiological characteristics of DEH in Japan were clarified.

Baseline neutrophil-to-lymphocyte ratio (NLR) is associated with clinical outcome in recurrent or metastatic head and neck cancer patients treated with nivolumab

Background: Nivolumab has been approved for recurrent or metastatic head and neck cancer (R/M HNC) on March 2017 in Japan. Recently, many researchers have been actively studying the prognostic and predictive markers. However, they have not been clarified. In this study, we evaluate the prognostic and predictive markers of the anticancer effect of nivolumab.Objective: This study assessed baseline neutrophil-to-lymphocyte ratio (NLR) as a prognostic and predictive marker for nivolumab efficacy in patients with recurrent/metastatic head and neck cancer (R/M HNC).Material and methods: This retrospective cohort study used medical records of patients with R/M HNC treated with nivolumab from May 2017 to January 2018 at a university hospital in Japan.Results: Twenty-nine patients (median age, 64 years) were included. In univariate analyses, baseline NLR ≥5 was significantly associated with overall survival (HR 4.88; p = .045) and progressive disease (HR 5.0; p = .046). More patients with baseline NLR ≥5 changed from nivolumab to best supportive care, compared to patients with baseline NLR <5 (64.3% vs 26.7%, respectively).Conclusions and significance: Baseline NLR was associated with clinical benefit from nivolumab in patients with R/M HNC. We propose that baseline NLR be used as a predictive or prognostic marker for nivolumab efficacy in these patients.

Localization of melatonin and its receptors (melatonin 1a and 1b receptors) in the mouse inner ear

Background: In the inner ear, evidence has been gathered indicating that melatonin plays important roles in inner ear physiology and pathophysiology. However, no attempt has been made previously to investigate the localization or expression of melatonin and its receptors in the whole inner ear. Aims/objectives: To analyze the presence of melatonin and its receptors in the normal mouse inner ear. Material and methods: C57BL6/J mice were used in this study. The localizations of melatonin, MT1a and MT1b in the inner ear, i.e. cochlea, vestibular end organs, vestibular ganglion and endolymphatic sac (ES), were studied by immunohistochemistry. Results: The organ of Corti, spiral ganglion, vestibular ganglion, vestibular sensory cells, vestibular dark and transitional cells, and ES epithelial cells showed an immunofluorescence reaction to melatonin, MT1a and MT1b. Conclusion and significance: The present findings show that melatonin and its receptors (MT1a and MT1b) are present in the inner ear, thus supporting the hypothesis that melatonin plays a physiological role in the inner ear.

Low-dose dexamethasone with fosaprepitant and palonosetron to prevent cisplatin-induced nausea and vomiting in head and neck cancer patients

OBJECTIVE

To determine if a lower dose of dexamethasone can be used in combination with fosaprepitant and palonosetron for cisplatin-induced nausea and vomiting in head and neck cancer patients, we conducted a single-center, two-arm, cross-over comparison study.

METHODS

Patients were randomly assigned to either standard dose dexamethasone group: intravenous 9.9 mg on day 1 and 6.6 mg on days 2-4 or low-dose dexamethasone group: intravenous 3.3 mg on days 1-4 for the first course and crossed over to the other treatment for the second course. The primary endpoint was complete response (CR) in the overall period.

RESULTS

Twenty-five patients were screened for the study and 22 were evaluable. Eleven patients were randomly assigned to the standard dose dexamethasone group and 12 patients to the low-dose dexamethasone group. The CR rate in the overall period was 86% in the standard dose group and 73% in the low-dose group, showing no significant difference (p = .61).

CONCLUSION

The efficacy of low-dose dexamethasone with fosaprepitant and palonosetron was not inferior to that of the standard dose dexamethasone in the highly emetogenic cisplatin-based treatment for head and neck cancer patients.

Gastric-type H+,K+-ATPase in mouse vestibular end organs

CONCLUSION

Gastric type H⁺,K⁺-ATPase in the vestibular end organs may be of importance for K⁺ circulation and may also be related to pH regulation in vestibular end organs and endolymphatic sac.

OBJECTIVE

To analyze the expression of gastric-type H⁺,K⁺-ATPase in normal mouse vestibular end organs.

METHODS

8 weeks old CBA/J mice were used in this study. The presence of gastric-type H⁺,K⁺-ATPase α and β in the vestibular end organs, viz. utricle, saccule, ampulla, vestibular ganglion, and endolymphatic sac, was investigated using immunohistochemistry.

RESULTS

In the vestibular end organs, H⁺,K⁺-ATPase α and β were almost identical. H⁺,K⁺-ATPase was expressed in sensory cells, the basolateral surface of dark cells, fibrocytes, in vestibular ganglion cells, and in the upper region of the endolymphatic sac epithelial cells.

Localization of histamine (H1, H2, H3 and H4) receptors in mouse inner ear

Conclusion The present findings show that all four types of histamine receptors (H1R, H2R, H3R, and H4R) are present in the inner ear, thus supporting the hypothesis that histamine plays a physiological role in the inner ear. Objective To analyse the presence of histamine receptors in the normal mouse inner ear. Methods CBA/J mice were used in this study. The localization of H1R, H2R, H3R, and H4R in the inner ear, i.e. cochlea, vestibular end organs, vestibular ganglion, and endolymphatic sac, was studied by real-time PCR and immunohistochemistry. Results The mRNA for each receptor sub-type was detected in the inner ear. In the immunohistochemical study, the organ of Corti, spiral ganglion, vestibular ganglion, vestibular sensory epithelium, and endolymphatic sac cells showed an immunofluorescent reaction to all histamine receptors.

Localization of sirtuins (SIRT1-7) in the aged mouse inner ear

CONCLUSION

The expression of sirtuin in vestibular end organs and cochlea responds differently to age-related changes. Down-regulation of SIRT1, 3, and 5 in the cochlea may weaken the protective activity regarding degeneration of the organ of Corti as well as of spiral ganglion cells, resulting in the development of age-related hearing loss. An increase in SIRT 1, 4, or 5 in vestibular tissue could indicate an increased need of detoxification of reactive oxygen species and an increased anti-ageing potential.

OBJECTIVE

To analyse the expression of sirtuins (SIRT1-7) in the normal young and old mouse inner ears.

METHODS

Young (8 weeks) and old (22 months) CBA/J mice were used in this study. Localization of SIRT1-7 in the inner ear, i.e. cochlea, vestibular end organs, and vestibular ganglion, was investigated using real-time PCR and immunohistochemistry.

RESULTS

In the vestibular end organs, the expression of SIRT1, 2, 4, 5 (both mRNA and protein), SIRT6, and 7 (only mRNA) was found to be increased, while a slightly decreased immunoreactivity was observed in SIRT3. In the cochlea, the expression of SIRT1, 3, and 5 (both mRNA and protein) was decreased in the old mice, whereas no noticeable difference was observed regarding SIRT2, 4, 6, or 7.

Long-term administration of vasopressin can cause Ménière's disease in mice

CONCLUSION

A new murine model of Ménière's disease has been developed, based on long-term administration of vasopressin. Induction of vestibular dysfunction in the present animal model can cause additional stress, by reducing inner ear blood flow. Latanoprost, a selective agonist for the FP prostanoid receptor, may become a new remedy for Ménière's disease.

OBJECTIVE

The purpose of this study was to develop a more suitable animal model, with a closer resemblance to the pathophysiological process in Ménière's disease.

METHODS

Adult CBA/J or ICR mice were treated by subcutaneous injection of vasopressin for 5 days up to 8 weeks. Morphological analyses were performed of the cochlea, vestibular end organs and endolymphatic sac. The effect of latanoprost on the development of endolymphatic hydrops was also examined.

RESULTS

All experimental animals showed mild to moderate endolymphatic hydrops, increasing in severity as the vasopressin treatment was prolonged. Animals treated with vasopressin for 8 weeks showed severe endolymphatic hydrops with partial loss of outer hair cells and spiral ganglion cells. These animals also had a reversible vestibular dysfunction following intratympanic injection of epinephrine. Latanoprost inhibited the development of endolymphatic hydrops caused by vasopressin.

Localization of sirtuins in the mouse inner ear

CONCLUSION

It is suggested that SIRT1 and 3, and probably SIRT4 and 5, play an important role in the neuroprotection of the inner ear. SIRT2 may be related to neuroprotection and myelin sheath formation, while SIRT6 seems to have a significant role in maintaining the energy balance by metabolic regulation.

OBJECTIVE

To analyze the expression of sirtuins (SIRT1-7) in the normal mouse inner ear.

METHODS

CBA/J mice were used for this study. The localization of SIRT1-7 in the inner ear, i.e. cochlea, vestibular end organs, and endolymphatic sac, was investigated using real-time PCR and immunohistochemistry.

RESULTS

We found high levels of mRNA of all seven sirtuins in the inner ear. In the immunohistochemical study, SIRT1-7 were abundant in many inner ear structures, i.e. stria vascularis, inner and outer hair cells, spiral ganglion cells, vestibular sensory and ganglion cells, vestibular dark and transitional cells, and the endolymphatic sac.

Localization of aquaporins in the mouse vestibular end organs

CONCLUSION

We found that aquaporins (AQPs) in the fluid transporting cells, such as vestibular dark cells and endolymphatic sac epithelial cells, seem to be of importance in fluid transport in the inner ear, while those in the sensory and ganglion cells may play a functional role in sensory cell transduction.

OBJECTIVE

Expression of AQPs (0-12) was analyzed in normal mouse vestibular end organs.

METHODS

CBA/J mice were used in this study. Localization of AQPs 0-12 in the vestibular end organs and endolymphatic sac was investigated by immunohistochemistry.

RESULTS

The AQPs were found abundantly distributed in many structures in the vestibular end organs, i.e. vestibular sensory and supporting cells, vestibular dark cells, vestibular ganglion cells, and the endolymphatic sac.

Expression of Trefoil factor family peptides in the nasal allergic mucosa

OBJECTIVE

Trefoil factor family peptides (TFFs) are the secretory products of mucous cells and are closely associated with mucins. TFFs appear to be important in mucosal healing processes. Although TFF1/3 are expressed in the human respiratory tract, their role in the nasal mucosa is not thoroughly understood. We investigated the association between TFFs and mucins and the role TFFs in the human nasal mucosa.

MATERIAL AND METHODS

Patients undergoing turbinectomy were included and it was determined whether patients had nasal allergies or not. The localization of TFF1/3, MUC5AC/5B expression was investigated using immunohistochemistry. The levels of the mRNA transcripts were examined using quantitative real-time PCR.

RESULTS

TFF1/3 had a similar pattern of localization in epithelial goblet cells and submucosal glandular cells. TFF1/3 co-localized with MUC5AC in the epithelium, and co-localized with MUC5B in the epithelium and the submucosal glandular cells. The levels of TFF1/3 and MUC5B mRNA in allergic patients were significantly increased.

CONCLUSION

Our results suggest that TFF1/3 may associate with MUC5AC and MUC5B in the nasal mucosa, and that up-regulation of TFF1/3 and MUC5B may play an important role in the clinical condition of the nasal allergic mucosa.

Expression of prostanoid receptors (EP1, 2, 3, and 4) in normal and methimazole-treated mouse olfactory epithelium

CONCLUSION

Prostanoid receptors (EP1, EP2, EP3, and EP4) are expressed in the olfactory epithelium (OE), and the EP4 prostanoid receptor may play an important role in the OE.

OBJECTIVE

The purpose of the present study was to investigate the expression and localization of the four types of prostanoid receptors (EP1, EP2, EP3, and EP4) in the OE of normal and methimazole-treated mice to gain more complete knowledge about the functional significance of the prostanoid receptors in OE.

METHODS

CBA/J mice were used in this study. The localization of the prostanoid receptors (EP1, EP2, EP3, and EP4) in the OE was investigated by immunohistochemistry. The changes in expression of prostanoid receptors were studied in methimazole-treated mice. Furthermore, the effect of EP agonists on the methimazole-induced degeneration of OE was assessed by morphological analysis and by assessment of apoptosis.

RESULTS

All four types of EP receptors were recognized in mouse OE. Expression of EP4 in the OE was significantly reduced after methimazole treatment. In the methimazole-treated mice, an EP4 agonist reduced OE damage and apoptosis.

Localization of aquaporins 1, 2, and 3 and vasopressin type 2 receptor in the mouse inner ear

CONCLUSION

It is suggested that aquaporins (AQPs) 1, 2, and 3, and vasopressin type 2 receptors (V2Rs) in the fluid transporting cells, such as stria vascularis, vestibular dark and transitional cells, and endolymphatic sac epithelial cells, have an important role in fluid transport in the inner ear, while those in the sensory and ganglion cells may play a functional role in the sensory cell transduction system.

OBJECTIVE

To analyze expression of AQP1, AQP2, and AQP3 as well as V2Rs in the normal mouse inner ear.

METHODS

CBA/J mice were used in this study. Localization of AQP1, AQP2, AQP3, and V2Rs in the inner ear, i.e. cochlea, vestibular end organs, and endolymphatic sac, was investigated by immunohistochemistry.

RESULTS

The results show that AQP1, AQP2, AQP3, and V2Rs are abundantly distributed in many inner ear structures, i.e. stria vascularis, inner and outer hair cells, spiral ganglion cells, vestibular sensory and ganglion cells, vestibular dark and transitional cells, and the endolymphatic sac.

Localization of prostanoid receptors in the mouse inner ear

CONCLUSION

EP4, EP2, and IP prostanoid receptors exert an otoprotective function and FP may be important for fluid homeostasis in the inner ear.

OBJECTIVE

To investigate the expression of prostanoid receptors in the normal mouse inner ear.

METHODS

CBA/J mice were used in this study. The localization of prostanoid receptors, i.e. DP, EP1, EP2, EP3, EP4, FP, IP, and TP, in the inner ear, i.e. the cochlea, vestibular end organs, endolymphatic sac, was studied by immunohistochemical techniques.

RESULTS

The EP4, IP, and FP prostanoid receptors were found to be abundantly distributed in many inner ear structures, i.e. stria vascularis, inner and outer hair cells, spiral ganglion cells, vestibular sensory and ganglion cells, and the endolymphatic sac. EP2 and EP3 are also localized in the inner ear whereas DP, EP1, and TP are only weakly expressed.

Expression of transient receptor potential channel vanilloid (TRPV) 1&#x2013;4, melastin (TRPM) 5 and 8, and ankyrin (TRPA1) in the normal and methimazole-treated mouse olfactory epithelium

Conclusion: It is suggested that TRPV1, 2, 3, and 4, TRPM5 and 8, and TRPA1 may play several roles in the olfactory epithelium (OE), contributing to olfactory chemosensation, olfactory adaptation, olfactory-trigeminal interaction, and OE fluid homeostasis. In patients with olfactory disturbance, TRPV1 and TRPM8 may be closely related to a high rate of recognition of curry and menthol odors, while TRPV2 may also play a crucial role in the regeneration of olfactory receptor neurons. Objective: Expression of TRPV1–4, TRPM5 and 8, and TRPA1 in the normal and methimazole-treated mouse OE was analyzed. Methods: The localization of TRPV1–4, TRPM5 and 8, and TRPA1 in the OE of normal and methimazole-treated CBA/J mice was investigated by immunohistochemistry. Results: Normal OE showed a positive immunofluorescent reaction to TRPV1–4, TRPM5 and 8, and TRPA1. In lamina propria, the nerve fibers displayed TRPV 1, 2, and 3, TRPM8 and TRPA1. In the pathological condition, the expression of TRPV3, TRPV4, TRPM5, and TRPA1 was markedly reduced and took a long time to recover. In contrast, expression of TRPM8 was scarcely affected, even in the pathological condition, while TRPV1 and TRPV2 showed early recovery following methimazole treatment.

Clinical characteristics of delayed endolymphatic hydrops in Japan: A nationwide survey by the Peripheral Vestibular Disorder Research Committee of Japan

CONCLUSION

Similarly to almost all delayed endolymphatic hydrops (DEH) cases with both precedent sudden deafness and mumps deafness, two-thirds of DEH cases with precedent deafness of unknown cause with onset in early childhood developed DEH symptoms within 40 years after the precedent deafness. In spite of the diagnosis of precedent deafness, viral labyrinthitis may build up the late endolymphatic hydrops in most DEH cases up to four decades.

OBJECTIVE

To clarify the characteristics of DEH in Japan.

METHODS

Clinical information on 198 DEH cases was collected by nationwide, multicenter surveys conducted by the Peripheral Vestibular Disorders Research Committee of Japan.

RESULTS

The incidence of the ipsilateral type of DEH was 47.5%, which was almost equal to that of the contralateral type. In both types of DEH, the most common diagnosis of precedent deafness was deafness of unknown cause with onset in early childhood: 43.9% in both types of DEH. Sudden deafness and mumps deafness were the subsequent diagnoses of precedent deafness. The distribution of time delay of the onset between precedent deafness of unknown cause with onset in early childhood and DEH was different from that between precedent sudden and mumps deafness and DEH.

Expression of transient receptor potential channel mucolipin (TRPML) and polycystine (TRPP) in the mouse inner ear

CONCLUSIONS

TRPML3 may play distinct roles in the inner ear, such as stereociliar organization, sensory cell transduction, and inner ear fluid homeostasis, and TRPP3 may be important for fluid homeostasis in the inner ear.

OBJECTIVE

To study the expression of TRPML1-3 and TRPP2, 3, and 5 in the mouse inner ear.

MATERIALS AND METHODS

Localization of TRPML1-3 and TRPP2, 3, and 5 in the inner ear of CBA/J mice was investigated by immunohistochemistry.

RESULTS

TRPML1-3 immunoreactivity was evident in the stria vascularis, spiral prominence, and spiral ligament. TRPML immunoreactivity was also observed in outer and inner hair cells, supporting cells, and spiral ganglion cells. The vestibular end organs, vestibular sensory cells, dark cells, and ganglion cells all showed immunoreactivity to TRPML. TRPP2 immunoreactivity was evident in the outer lining of the lateral wall of the cochlea, spiral ganglion cells, vestibular sensory cells, and ganglion cells. TRPP3 immunoreactivity was present in stria vascularis, spiral ganglion cells, vestibular sensory cells, dark cells, and ganglion cells. Faint TRPP5 immunoreactivity was observed in the spiral ganglion cells and vestibular ganglion cells.

Effects of age and sex on the expression of estrogen receptor alpha and beta in the mouse inner ear

CONCLUSION

Estrogen receptor (ER) alpha and beta were expressed in the inner ear, and expression decreased with increasing age. ERalpha may alter cochlear and vestibular sensory transduction, and ERbeta may have a neuroprotective function in the inner ear.

OBJECTIVE

Expression of ERalpha and ERbeta in the mouse inner ear and its alterations with sex and aging were analyzed.

MATERIALS AND METHODS

Male and female CBA/J mice aged 8 weeks and 24 months were used. The localization and the intensity of ERalpha and ERbeta immunoreactivity in the inner ear of young and old mice of both sexes were investigated by immunohistochemistry.

RESULTS

ERalpha and ERbeta were co-expressed in the inner ear, i.e. in the nuclei of stria vascularis, outer and inner hair cells, spiral ganglion cells and vestibular ganglion cells, vestibular dark cells and endolymphatic sac. Strial marginal cells, outer hair cells and type II ganglion cells showed less expression of ERalpha. No gender- or age-related difference was noted in the expression pattern of ERalpha or ERbeta, but fluorescence intensity of ERalpha was stronger in young female mice than in young male mice. In contrast, ERbeta revealed no significant difference. In the old mice, fluorescence intensities of both ERalpha and ERbeta were significantly decreased in both sexes.

Expression of transient receptor potential vanilloid (TRPV) families 1, 2, 3 and 4 in the mouse olfactory epithelium

We investigated the expression of transient receptor potential vanilloid (TRPV)-1-4 in the mouse olfactory epithelium (OE) in comparison to its expression in respiratory epithelium. CBA/J mice were used. The localization of TRPV-1, -2, -3 and -4 in the nasal mucosa was investigated using immunohistochemistry and a double staining study for TRPV-1 and -2 and SP was also carried out. TRPV-1-4, were expressed variably in the OE with a diffuse pattern in lamina propria, and were expressed in respiratory epithelium with strong positive expression in glandular cells of lamina propria. The double-staining study revealed coexpression of TRPV-1 and -2 and substance P (SP) in the trigeminal nerve fibers of the OE. Coexpression of TRPV-1 and SP was marked around the blood vessels and seromucinous gland of respiratory epithelium while TRPV-2 showed no co-localization. TRPV-1-4 were found to be localized in the mouse OE and respiratory epithelium. Our results suggest that TRPVs may play multiple roles in the OE, contributing to olfactory adaptation, olfactory/trigeminal interactions in nasal chemoreception and OE homeostasis; they may also be involved in olfactory transduction as well as olfactory dysfunction secondary to sinonasal inflammatory disease. TRPVs in respiratory mucosa may play a significant role in nasal nociception, ciliary movement and the regulation of mucous secretion.

Age-dependent changes in the expression of klotho protein, TRPV5 and TRPV6 in mouse inner ear

CONCLUSIONS

Klotho protein content decreases with increasing age, which weakens resistance to oxidative stress, resulting in induced cell death as well as modulating endolymph fluid homeostasis. Down-regulation of klotho also leads to down-regulation of TRPV5 and TRPV6, resulting in modified Ca(2+) homeostasis in the inner ear, dysfunction of sensory cell transduction and causing hearing loss and/or vestibular disorders.

OBJECTIVE

Expression of klotho, TRPV5 and TRPV6 in the mouse inner ear and age-related changes were analysed.

MATERIALS AND METHODS

CBA/J mice aged 8 weeks and 24 months were used in this study. The localization of klotho, TRPV5 and TRPV6 in the inner ear of young and old mice was investigated by immunohistochemistry.

RESULTS

Immunostaining for klotho was observed in stria vascularis, outer and inner hair cells (OHCs and IHCs), and in vestibular sensory cells and dark cells, and less intensely in the spiral and vestibular ganglion cells. Expression of TRPV5 was found in stria vascularis, organ of Corti, vestibular sensory cells and dark cells, and less intensely in the spiral and vestibular ganglion cells. Expression of TRPV6 was found in supporting cells of the organ of Corti, with weak labelling in OHCs and IHCs. Weak fluorescence was also noted in stria vascularis, and faint fluorescence in the spiral ligament. Vestibular sensory and dark cells as well as vestibular ganglion cells showed weak fluorescence. In the old animals, the expression patterns of klotho, TRPV5 and TRPV6 were identical with those in young animals, although fluorescence intensity was significantly weaker.

Expression of canonical transient receptor potential channel (TRPC) 1-7 in the mouse inner ear

CONCLUSION

It is suggested that TRPCs play a functional role in the sensory cell transduction system in the inner ear.

OBJECTIVE

To study expression of TRPC 1-7 in the mouse inner ear.

MATERIALS AND METHODS

The localization of TRPC 1-7 in the inner ear of CBA/J mice was investigated by immunohistochemistry.

RESULTS

TRPC immunoreactivity was observed generally in the inner ear, e.g. in the lateral wall of the cochlea, organ of Corti, spiral ganglion, vestibular end organs and vestibular ganglion. The immunofluorescent reaction to TRPC 3, 4, 5, and 7 in the stria vascularis was more intense than in the spiral prominence or spiral ligament. In the organ of Corti, TRPC immunoreactivity was observed in the outer hair cells (OHCs), inner hair cells (IHCs) and some supporting cells. TRPC 1-7 were all present in the ganglion cell body, TRPC 1 and 3 showing intense fluorescence, TRPC 2 and 7 moderate fluorescence and TRPC 4, 5 and 6 weak staining in ganglion fibres. In the vestibular end organs, vestibular hair cells (VHCs) showed immunoreactivity to all TRPCs. Nerve fibres in the subepithelial tissue were stained by TRPC 1, 3, 5, 6 and 7. Immunofluorescence to TRPC 1, 3, 4, 5, 6 and 7 was observed in the dark cells. In the vestibular ganglion, TRPC 1-7 were all present in the ganglion cell body. TRPC 1-4 and 7 elicited immunofluorescence in ganglion fibres.

Expression of transient receptor potential channel melastin (TRPM) 1-8 and TRPA1 (ankyrin) in mouse inner ear

CONCLUSIONS

It has been shown that TRPMs may play a functional role in sensory cell physiology, fluid homeostasis, sensory cell death, and thermosensation in the inner ear, while TRPA1 plays an important role in sensory transduction.

OBJECTIVE

To study expression of TRPM1-8 and TRPA1 in the mouse inner ear.

MATERIALS AND METHODS

The localization of TRPM1-8 and TRPA1 in the inner ear of normal and gentamicin-treated CBA/J mice was investigated by immunohistochemistry.

RESULTS

The stria vascularis displayed a positive immunofluorescent reaction to TRPM1, 2, 3, 6, and 7. In the organ of Corti, outer and inner hair cells (OHCs and IHCs) showed positive immunofluorescence to TRPM1, 2, 3, 6, 7, and 8. Spiral ganglion cells were immunoreactive to TRPM1, 2, 3, 6, 7, and 8. The nerve fibers in the spiral ganglion cells and the nerves innervating the OHCs or IHCs were noticeably immunofluorescent to TRPM8 and TRPA1. In the vestibular end organs, vestibular sensory cells showed immunofluorescence to TRPM1, 2, 3, 6, and 7. The vestibular dark cells showed immunofluorescence to TRPM1, 3, 6, and 7; only the apical portion reacted to TRPM4. The nerve fibers innervating the vestibular sensory cells were distinctly reactive to TRPM8 and TRPA1, while the vestibular ganglion cells reacted to TRPM1, 2, 3, 6, 7, and 8.

The statoconial membrane of the guinea pig utricular macula. Scanning electron microscopic investigation combined with the freeze-fracturing technique

The superstructure of the guinea pig utricular macula was investigated using scanning electron microscopy combined with the freeze-fracturing technique. The statoconial membrane was composed of the otoconial layer, otolithic membrane and subcupular meshwork. The otolithic membrane consisted of closely arranged filaments with beaded appearance and densely packed globular matrix near the otoconial layer. The subcupular meshwork consisted of long branching filaments cross-bridged to one another. The filaments were continuous with those of the otolithic membrane on one side and with the surface of the epithelium on the other, which fills the space between the otolithic membrane and the macular surface. The otolithic membrane would function as a rigid plate and equally distribute the shear force of the otoconial layer to all the ciliary bundles. The subcupular meshwork may play an important role in transmitting the shear strain of the otolithic membrane to all the ciliary bundles and may also exert an additional dampening effect to prevent unwanted vibration.

Expression of transient receptor potential vanilloid (TRPV) 1, 2, 3, and 4 in mouse inner ear

CONCLUSION

It is suggested that transient receptor potential vanilloids (TRPVs) may play a functional role in cell physiology and TRPV-4 and -2 may play an important part in fluid homeostasis in the inner ear.

OBJECTIVE

Expression of TRPV-1, -2, -3, and -4 in the normal mouse inner ear was studied.

MATERIALS AND METHODS

CBA/J mice were used in this study. The localization of TRPV-1, -2, -3, and -4 in the inner ear, i.e. cochlea, vestibular end organs, and endolymphatic sac, was investigated by immunohistochemistry.

RESULTS

TRPV-1, -2, and -3 were co-expressed in hair cells and supporting cells of the organ of Corti, in spiral ganglion cells, sensory cells in vestibular end organs, vestibular ganglion cells, and sensory nerve fibers. TRPV-2 was also detected in the stria vascularis, dark cells, and endolymphatic sac. TRPV-4 was expressed in hair cells and supporting cells of the organ of Corti, in marginal cells of the stria vascularis, spiral ganglion cells, vestibular sensory cells, vestibular dark cells, vestibular ganglion cells, and epithelial cells of the endolymphatic sac.

Localization of transient receptor potential vanilloid (TRPV) in the human larynx

CONCLUSION

Transient receptor potential vanilloid (TRPV) 1, 2, 3, and 4 were expressed in the human larynx, which may act as laryngeal nociceptors perceiving luminal noxious stimuli, play an important role in thermal sensation and osmotic sensation, and are also related to some pathological conditions and prevention of aspiration.

OBJECTIVE

Expression of TRPV1, 2, 3, and 4 in the human larynx was analyzed.

MATERIALS AND METHODS

Specimens of human epiglottic epithelium obtained from six patients were used in this study. The localization of TRPV1, 2, 3, and 4 in the laryngeal epithelium was investigated by immunohistochemistry.

RESULTS

Immunohistochemical study revealed the presence of TRPV1, 2, 3, and 4 in the laryngeal epithelial cells. Chemoradiotherapy may reduce the expression of TRPV1, 2, 3, and 4, which might be a result of the mucositis and neuropathy in laryngeal epithelium.

Effect of inner ear blood flow changes in Ménière's model mice

CONCLUSIONS

The endolymphatic sac (ES) is important for inner ear fluid homeostasis. A dysfunctional ES can cause vertigo attacks following additional stress such as a sudden change in endolymphatic volume and/or pressure, or restricted inner ear blood flow.

OBJECTIVE

The purpose of this study was to elucidate the mechanism of vertigo attacks in Ménière's disease.

MATERIALS AND METHODS

Adult CBA/J mice were given an intratympanic injection of lipopolysaccharide and an intraperitoneal injection of aldosterone. These 'model' animals had epinephrine or sodium nitroprusside (SNP) instilled into the middle ear cavity. Cochleae, vestibules, and endolymphatic sacs were studied morphologically by light microscopy.

RESULTS

The injection of epinephrine into the model animals reduced the endolymphatic hydrops in the cochlea, but also produced mild hydrops in the vestibule, which was never observed in untreated (control) animals. The ES did not react to epinephrine in the normal way. Injection of SNP did not cause any changes.

Changes in transient receptor potential vanilloid (TRPV) 1, 2, 3 and 4 expression in mouse inner ear following gentamicin challenge

CONCLUSION

It is suggested that transient receptor potential vanilloid (TRPV)-1 and -2 may be of pathological significance for sensory cells and ganglions, while TRPV-3 and -4 may play an important part in neuroprotection of the inner ear.

OBJECTIVE

Changes in the expression of TRPV-1, -2, -3, and -4 in gentamicin (GM)-treated mouse inner ear were studied.

MATERIALS AND METHODS

CBA/J mice were used in this study. The localization of TRPV-1, -2, -3, and -4 in the inner ear of both untreated and GM-treated CBA/J animals (intratympanic injection of 5 mg GM) was investigated by immunohistochemistry.

RESULTS

TRPV-1, -2, and -3 were co-expressed in the inner ear sensory and ganglion cells, while TRPV-4 was also expressed in the stria vascularis and vestibular dark cells. Following GM treatment, the intensity of immunofluorescent reaction to TRPV-1 and TRPV-2 increased, while that to TRPV-3 and TRPV-4 decreased.

Changes in the characteristics of definite Meniere's disease over time in Japan: a long-term survey by the Peripheral Vestibular Disorder Research Committee of Japan, formerly the Meniere's Disease Research Committee of Japan

CONCLUSION

The incidence of new cases of Meniere's disease (MD) in elderly patients aged 60 years or more was found to have increased over time after correction for age distribution in the overall population. Job- and care-related fatigue may be involved in the recent increase in elderly-onset cases because physical and mental fatigue can induce onset of the disease.

OBJECTIVES

Changes over time in the epidemiologic characteristics of MD in Japan were analyzed.

MATERIALS AND METHODS

Between 1975 and 2006, four nationwide, multi-center surveys of MD were conducted by the Meniere's Disease Research Committee of Japan (1975-1976) and the Peripheral Vestibular Disorders Research Committee of Japan (1982-1984, 1990, and 2001-2006). Information was collected by the committee members on a total of 1368 de novo cases of definite MD, 520 reported in the first survey, 290 in the second survey, 148 in the third survey, and 410 in the fourth survey.

RESULTS

Clear changes were seen over time in the population-adjusted sex distribution of the disease and population-adjusted age at onset. The number of definite MD cases in females increased over time relative to the number of cases in males. The proportion of cases in which onset occurred at 60 years of age or more increased over time when the number of cases in each age group was adjusted for changes in age distribution of the population over time. From the time of the third survey, there was a slight increase in the proportion of cases with bilateral involvement.

Protective effect of edaravone against tobramycin-induced ototoxicity

CONCLUSION

It is suggested that simultaneous treatment with the radical scavenger edaravone has an effective protective effect against tobramycin ototoxicity in rat. Even if the edaravone treatment is postponed for 7 days, it can still prevent hearing loss, but a 14 day delay cannot protect from ototoxicity.

OBJECTIVES

With the aim of alleviating hearing loss caused by aminoglycoside ototoxicity, we performed a trial to assess the hearing protective efficacy of the radical scavenger edaravone.

MATERIALS AND METHODS

In part one of the study, 21 male Sprague-Dawley albino rats were used; 2 rats served as controls for the safety of edaravone. Eight rats each received 10 subcutaneous injections (s.c.) of tobramycin (160 mg/kg b.w.) once daily and saline injection intraperitoneally for 2 weeks. Eleven rats were given 10 s.c. tobramycin injections simultaneously with an intraperitoneal injection of edaravone (3 mg/kg b.w.). In part two, tobramycin was injected in 13 rats (as above). Five of these received two edaravone injections 7 days later and four rats similarly 14 days later. Auditory brainstem response (ABR) was used to assess hearing.

RESULTS

All rats treated only with tobramycin showed a deterioration of hearing. None of the rats given simultaneous treatment with tobramycin and edaravone demonstrated hearing loss. A 7 day delay in edaravone injection still prevented hearing loss, but a 14 day delay had only a temporary prophylactic effect.

Radical scavengers for elderly patients with age-related hearing loss

CONCLUSION

The results of this study suggest that treatment with radical scavengers has the potential to become an effective new therapy for age-related hearing loss.

OBJECTIVE

To assess the efficacy of treatment with radical scavengers for age-related hearing loss.

SUBJECTS AND METHODS

Rebamipide (300 mg/day), alpha-lipoic acid (60 mg/day), and vitamin C (600 mg/day) were given orally for at least 8 weeks to 46 elderly patients with age-related hearing loss.

RESULTS

Hearing levels after treatment were significantly improved at all frequencies.

Effect of inner ear blood flow changes on the endolymphatic sac

CONCLUSIONS

That the endolymphatic sac (ES) reacts to changes in inner ear blood flow may be important for homeostasis of the inner ear fluid volume and pressure.

OBJECTIVES

To elucidate the effect of changes in inner ear blood flow on the ES and to learn more about the volume and pressure regulatory function of the ES.

MATERIALS AND METHODS

Epinephrine or sodium nitroprusside (SNP) was injected into the middle ear cavity of adult CBA/J mice. The ES were analyzed morphologically by light microscopy.

RESULTS

Epinephrine reduced the luminal size of the ES leading to an accumulation of intraluminal homogeneous substance. Injection of SNP increased the size of the ES lumen, accompanied by a collapse of the lateral intercellular space (LIS) and dense perisaccular tissue. These changes were almost reversed 4 h after injection.

Effects of hydrogen peroxide on vestibular hair cells in the guinea pig: importance of cell membrane impairment preceding cell death

CONCLUSION

Our findings indicate that oxidative stress induces morphological changes in vestibular hair cells and subsequently leads to cell death after 2.5 h.

OBJECTIVES

The aim of this study was to confirm the direct effects of oxidative stress on vestibular hair cells.

MATERIALS AND METHODS

Vestibular hair cells isolated from guinea pigs were loaded with 1 or 10 mM H2O2, and morphological changes were observed. In addition, in a viability/cytotoxicity assay system, the numbers of dead cells in isolated cristae ampullares were counted 1, 3, and 5 h after loading with H2O2 or artificial perilymph (control).

RESULTS

Reactive oxygen, in the form of H2O2, directly affects the cell membrane of isolated vestibular hair cells and causes swelling of the cell body, bleb formation, and shortening of the neck region. Morphological changes occur within 30 min after loading with H2O2, but a significant increase in the number of dead cells is noted only after 3 h.

Spatiotemporal expression of cochlin in the inner ear of rats during postnatal development

Cochlin (encoded by COCH) constitutes 70% of non-collagenous protein in the inner ear, and the expression of cochlin is highly specific to the inner ear. Eleven missense mutation and one in-frame deletion have been reported in the COCH gene, causing hereditary progressive sensorineural hearing loss and vestibular dysfunction, DFNA9. These data imply that cochlin should bear an essential and crucial role in the inner ear function. However, the role of cochlin has not been fully clarified. We have investigated the spatiotemporal expression of cochlin in the inner ear of rats during postnatal development to better understand the functional role of cochlin. By immunohistochemistry, cochlin expression was faint in the cochlea and vestibule on the 6th day after birth (DAB6). At DAB70, strong expression of cochlin was detected in the spiral limbus and spiral ligament within the cochlea, and in the stromata of the maculae of otolithic organs and crista ampullaris within the vestibule. Immunoreactivity for cochlin increased during the postnatal development. Western blot analysis also showed an increase in the expression of cochlin isoforms. Furthermore, the dominant isoform of cochlin expressed changed from p63s to p40s between DAB24 and DAB70. These results suggest that the expression of cochlin may be related to the maturation of inner ear function, and the change in isoforms of cochlin expressed will provide important insight into the understanding of both cochlin function and formation of cochlin isoforms. This is the first to report about the spatiotemporal expression of cochlin in the developing rat inner ear.

Localization of transient receptor potential channel vanilloid subfamilies in the mouse larynx

CONCLUSION

Laryngeal epithelium contains TRPV1, 2, 3 and 4, which may act as laryngeal nociceptors perceiving luminal noxious stimuli, play an important role in thermal sensation, osmotic sensation, and are also related to pathological conditions, such as inflammatory response, genesis of cough, asthma.

OBJECTIVE

Expression of TRPV1, 2, 3 and 4 in the normal CBA/J mouse larynx was analysed.

MATERIALS AND METHODS

CBA/J mice were used in this study. The localizations of TRPV1, 2, 3 and 4 in the laryngeal epithelium were investigated by immunohistochemistry.

RESULTS

Immunohistochemical study revealed the presence of TRPV1, 2, 3 and 4 in the laryngeal epithelial cells. TRPV1 and TRPV2 were often co-localized with substance P, while the co-localization of substance P and TRPV3 was rare and TRPV4 was not co-localized with substance P.

Effect of acute endolymphatic hydrops overload on the endolymphatic sac

CONCLUSIONS

Homeostasis of endolymph volume is a complex mechanism, in which the endolymphatic sac (ES) may play an important role.

OBJECTIVES

To elucidate the effect of acute endolymphatic hydrops (EH) on the ES and to gain further information about the volume and pressure regulative function of the ES.

MATERIALS AND METHODS

Distilled water was injected into the middle ear cavity of adult CBA/J mice. The ESs were studied morphologically by light and transmission electron microscopy.

RESULTS

Mild EH was found, particularly in the upper turn of the cochlea. Acute EH led to an increase in the size of the ES lumen, accompanied by collapse of the lateral intercellular spaces and dense perisaccular tissue, changes which had reversed 2 h after the injection.

A new animal model for Ménière's disease

CONCLUSION

A new murine model for the study of Ménière's disease has been developed by treatment with both lipopolysaccharide (LPS) and aldosterone. Induction of vestibular dysfunction in the hydropic animal model may entail additional stress such as reduced inner ear blood flow, and sudden acute changes in endolymph volume and/or pressure.

OBJECTIVE

The purpose of this study was to develop a more suitable animal model, showing closer resemblance to the pathophysiological process in Ménière's disease.

MATERIALS AND METHODS

Adult CBA/J mice were treated by intratympanic injection of LPS, intraperitoneal injection of aldosterone, or injection of both LPS and aldosterone. Morphological analyses were performed in the cochlea and endolymphatic sac.

RESULTS

All experimental animals showed mild to moderate endolymphatic hydrops. Those treated with both LPS and aldosterone showed reversible vestibular dysfunction after the intratympanic injection of epinephrine.

Protective effect of edaravone against endolymphatic hydrops

CONCLUSION

Our findings suggest that edaravone prevented the production of reactive oxygen species (ROS). Edaravone also delayed the formation of endolymphatic hydrops in guinea pigs, but had no effect on endolymphatic hydrops.

OBJECTIVE

To analyse the protective effect of a free radical scavenger, edaravone, on endolymphatic hydrops.

MATERIALS AND METHODS

Guinea pigs were subjected to surgical obliteration of the endolymphatic duct (ED). For the detection of ROS, group 1 received intraperitoneal injections of edaravone (3 mg/kg/day) for 2 days, group 2 received edaravone for 2 weeks, group 3 saline for 2 days, and group 4 saline for 2 weeks. ROS production by the organ of Corti and stria vascularis was examined by using dihydrotetramethylrosamine. For the morphological analysis, guinea pigs were divided into five groups, i.e. 2 or 4 weeks after ED obliteration, 2 weeks with edaravone, first or last 2 weeks with edaravone and sacrificed 4 weeks after ED obliteration. Increases in the ratios of the cross-sectional area of scala media were analysed quantitatively to assess the degree of endolymphatic hydrops among the above-mentioned five groups of the hydropic cochlea.

RESULTS

ROS was detected both in the organ of Corti and in the lateral wall of cochleae 2 days after ED obliteration. Edaravone prevented the production of ROS and also attenuated the formation of endolymphatic hydrops in the acute hydrops group.

Expressions of Aquaporin-2, Vasopressin Type 2 Receptor, Transient Receptor Potential Channel Vanilloid (TRPV)1, and TRPV4 in the Human Endolymphatic Sac

OBJECTIVE

To localize aquaporin (AQP)2, vasopressin type 2 receptor (V2-R), and transient receptor potential channel vanilloid subfamily 1, 4 (TRPV1, TRPV4) in the human endolymphatic sac (ES).

METHODS

Three samples of human ES were sampled during the removal of vestibular schwannoma by way of the translabyrinthine approach. The samples were immediately fixed in 4% paraformaldehyde and embedded in OCT compound; immunohistochemistry was performed with AQP2, V2-R, TRPV1, and TRPV4 polyclonal antibodies.

RESULTS

AQP2, V2-R, TRPV1, and TRPV4 proteins were detected in the epithelial layer of the ES but were not observed in connective tissue around the ES. TRPV1 was also expressed in blood vascular endothelial cells of the connective tissue of ES.

CONCLUSIONS

AQP2, V2-R, and TRPV4 were expressed in the luminal epithelium of human ES. The same characteristic distribution of water and ion channels is seen in the kidney, where a significant amount of fluid is filtrated and resorbed. ES probably plays an active role in the homeostasis of the endolymph.

Ménière's disease: a long-term follow-up study of bilateral hearing levels

CONCLUSION

It is suggested that a holistic factor - such as psychological stress--is involved in Menière's disease (MD) and that the pathological changes in MD may be a result not only of endolymphatic hydrops but also of disorders affecting the entire cochlea.

PATIENTS AND METHODS

Changes in the hearing of 51 patients with unilateral MD were investigated to ascertain the correlation between changes in hearing loss (a) in the affected ear vs the contralateral ear and (b) at low frequencies vs high frequencies.

RESULTS

About half of the MD patients showed a significant positive correlation between the hearing level in the affected ear and that in the contralateral ear and also between the average hearing level at lower frequencies and that at 8 kHz. These tendencies were more pronounced in patients with severe fluctuation of hearing and/or severe hearing loss.

Protective effect of edaravone against the ototoxicity of Pseudomonas aeruginosa exotoxin A

CONCLUSION

Our findings suggest that edaravone can protect against cochlear damage caused by Pseudomonas aeruginosa exotoxin A (PaExoA).

OBJECTIVE

To analyze the protective effect of a free radical scavenger, edaravone, against the ototoxicity resulting from exposure of the middle ear to PaExoA.

MATERIAL AND METHODS

In nine groups of albino rats the following solutions were instilled either via the tympanic membrane into the round window niche [intratympanically (i.t.)] or intravenously (i.v.): edaravone (i.v.); edaravone (i.t.); PaExoA (i.t.) + edaravone (i.t.; simultaneously); PaExoA (i.t.) + edaravone (i.t.; 1 h after); PaExoA (i.t.) + edaravone (i.t.; 24 h after); PaExoA (i.t.) + edaravone (i.v.; simultaneously); PaExoA (i.t.) + edaravone (i.v.; 1 h after); PaExoA (i.t.) + edaravone (i.v.; 24 h after); PaExoA (i.t.) + saline (i.v.). Frequency-specific (2-20 kHz) auditory brainstem responses were measured to determine hearing thresholds before and 2, 5 and 10 days after instillation.

RESULTS

PaExoA had penetrated from the middle ear into the cochlea and caused hearing loss. This impairment was blocked by intratympanic injection of edaravone when given simultaneously or 1 h after the first instillation of PaExoA, or by intravenous injection of edaravone when given simultaneously. There were significant differences in protective effect between the intratympanic and intravenous routes.

Expression of Cochlin in the Vestibular Organ of Rats

The COCH gene mutated in autosomal dominant sensorineural deafness (DFNA9) encodes cochlin, a major constituent of the inner ear extracellular matrix. Cochlin constitutes 70% of the inner ear protein and cochlin isoforms can be classified into three subgroups, p63s, p44s and p40s. Symptoms of some DFNA9 patients are consistent with those of Ménière's disease. Here, we report the expression of cochlin in the vestibular organ of rats using isoform-specific antibodies that recognize all three isoforms. Cochlin is highly expressed in the stromata of the maculae of otolithic organs and cristae of semicircular canals, and in the channels in the bony labyrinth that transmit the dendritic innervation to the cristae and maculae. Cochlin cannot be detected in the sensory cells, dark cells, nor in the acellular structures, otolithic membrane or in the cupula. These findings support the theory that deposition of acidophilic substance in the inner ear caused by mutation of cochlin can induce a secondary retrograde dendritic degeneration of the vestibular nerves.