Predictive value of local control by 4'-[methyl-11C]-thiotymidine PET volume parameters in p16-negative oropharyngeal, hypopharyngeal, and supraglottic squamous cell carcinoma.

PURPOSE: We investigated the potential of baseline 4'-[methyl- 11 C]-thiothymidine ([ 11 C]4DST) PET for predicting loco-regional control of head and neck squamous cell carcinoma (HNSCC). METHODS: A retrospective analysis was performed using volumetric parameters, such as SUVmax, proliferative tumor volume (PTV), and total lesion proliferation (TLP), of pretreatment [ 11 C]4DST PET for 91 patients with HNSCC with primary lesions in the oral cavity, hypopharynx, supraglottis, and oropharynx, which included p16-negative patients. PTV and TLP were calculated for primary lesions and metastatic lymph nodes combined. We examined the association among the parameters and relapse-free survival and whether case selection focused on biological characteristics improved the accuracy of prognosis prediction. RESULTS: The area under the curves (AUCs) using PTV and TLP were high for the oropharyngeal/hypopharyngeal/supraglottis groups (0.91 and 0.87, respectively), whereas that of SUVmax was 0.66 ( P  < 0.01). On the other hand, the oral group had lower AUCs for PTV and TLP (0.72 and 0.77, respectively). When all cases were examined, the AUCs using PTV and TLP were 0.84 and 0.83, respectively. CONCLUSION: Baseline [ 11 C]4DST PET/CT volume-based parameters can provide important prognostic information with p16-negative oropharyngeal, hypopharyngeal, and supraglottic cancer patients.

Estimated incidence and characteristics of vestibular neuritis in Japan: A nationwide survey.

OBJECTIVE: To assess the annual incidence of vestibular neuritis (VN) in the Japanese population. METHODS: We conducted a mail-based survey targeting otolaryngologic clinics and hospitals across Japan to estimate the annual number of patients who were newly-diagnosed with VN during the one-year period of 2021. Using a stratified sampling method, we selected 1,107 departments and asked them to report the number of new patients with VN and their demographics. The total number of VN patients was estimated by multiplying the reported numbers by the reciprocal of the sampling rate and response rate. RESULTS: The overall survey response rate was 40.5 % (448 departments). The estimated number of newly-diagnosed VN patients in 2021 was 8,861 (95 % confidential interval [CI], 2,290-15,432) The annual incidence of VN was 7.05 per 100,000 population in Japan. The male-to-female ratio of VN patients was 0.96, and the mean age was 60.3 ± 16.1 years (range 11-94 years). CONCLUSIONS: The annual incidence of VN in Japan in 2021 had almost doubled and the mean age had become older compared to the previous study in 1993 (annual incidence; 3.5 per 100,000 per year; mean age: 45 years).

The Utility of Glasgow Prognostic Score and Palliative Prognostic Index in Patients With Head and Neck Squamous Cell Carcinoma Under Palliative Care.

OBJECTIVES: Palliative care patients with head and neck squamous cell carcinoma (HNSCC) often experience dysphagia and airway trouble; thus, each patient requires a specific palliative care plan based on their prognostication. However, no established specific prognostic tool performed on the day of starting end-of-life care is available for such patients. We assessed the accuracy of Glasgow prognostic score (GPS) and palliative prognostic index (PPI) and their combination to establish a specified prognostic tool for patients with HNSCC in end-of-life setting. METHODS: A retrospective clinical chart review was undertaken on patients with HNSCC in end-of life setting who were decided in Kagawa University Hospital and National Hospital Organization Shikoku Cancer Center between April 2011 and March 2019. The patients were divided into 2 categories according to GPS (0-1 and 2) and PPI (groups A-B and C). These were combined into 4 categories (PPI group A-B and GPS score 0-1: good; PPI group A-B and GPS score 2: intermediate; PPI group C and GPS score 2: poor; and PPI group C and GPS score 0-1: others). The survival curves were compared for the former 3 categories. RESULTS: The median survival of the scores 0-1 and 2 on GPS were 114 (72-148) and 39 (25-52) days, respectively (P < .01). These of groups A-B and C on PPI were 79 (64-99) and 16 (9-29) days, respectively (P < .01). The median survival of the good, intermediate, and poor categories was 127 (73-149), 64 (44-80), and 15 (9-27) days, respectively (P < .01 among all categories). CONCLUSIONS: In this study, the survival of terminally ill patients with HNSCC can be predicted by the GPS, PPI, and their combination with sufficient probability.

Low-salt diet increases mRNA expression of aldosterone-regulated transporters in the intermediate portion of the endolymphatic sac.

The endolymphatic sac is a small sac-shaped organ at the end of the membranous labyrinth of the inner ear. The endolymphatic sac absorbs the endolymph, in which the ion balance is crucial for inner ear homeostasis. Of the three sections of the endolymphatic sac, the intermediate portion is the center of endolymph absorption, particularly sodium transport, and is thought to be regulated by aldosterone. Disorders of the endolymphatic sac may cause an excess of endolymph (endolymphatic hydrops), a histological observation in Meniere's disease. A low-salt diet is an effective treatment for Meniere's disease, and is based on the assumption that the absorption of endolymph in the endolymphatic sac abates endolymphatic hydrops through a physiological increase in aldosterone level. However, the molecular basis of endolymph absorption in each portion of the endolymphatic sac is largely unknown because of difficulties in gene expression analysis, resulting from its small size and intricate structure. The present study combined reverse transcription-quantitative polymerase chain reaction and laser capture microdissection techniques to analyze the difference of gene expression of the aldosterone-controlled epithelial Na+ channel, thiazide-sensitive Na+-Cl- cotransporter, and Na+, K+-ATPase genes in the three individual portions of the endolymphatic sac in a rat model. A low-salt diet increased the expression of aldosterone-controlled ion transporters, particularly in the intermediate portion of the endolymphatic sac. Our findings will contribute to the understanding of the physiological function of the endolymphatic sac and the pathophysiology of Meniere's disease.

Comparison of the accuracy of clinical prediction of survival and palliative prognostic index for patients with head and neck squamous cell carcinoma in the end-of-life setting.

OBJECTIVE: In the end-of-life stage of head and neck squamous cell carcinoma (HNSCC), predicting survival is essential to determine treatment procedure and place of care. Several reports have compared actual survival (AS) and clinical prediction of survival (CPS), a subjective prognostic prediction by attending physicians. However, specific studies focusing on patients with HNSCC are limited. Likewise, a comparison of the accuracy of CPS and palliative prognostic index (PPI), a prognostic tool using subjective assessment, has not been sufficiently investigated. This study aimed to clarify the correlation between AS and CPS/PPI and compare the accuracy of CPS and PPI in end-stage HNSCC. METHODS: This retrospective study included patients with HNSCC in the end-of-life setting. Patients were recruited from the National Hospital Organization Shikoku Cancer Center between April 2011 and March 2019. Data on basic demography and clinical parameters when patients decided to start end-of-life care at the head and neck oncology division were collected. We examined the correlation between AS and CPS using Spearman's correlation coefficients. The area under the receiver operating characteristic curve of CPS and PPI for 30-day survival prediction were compared for predictive accuracy. RESULTS: Among 98 eligible patients, 59 patients were enrolled in this study and analyzed. Of the 59 patients, CPS and PPI were calculated for 30 patients, whereas, only the PPI was calculated for 29 patients. The median AS and CPS were 35 (IQR: 9-73) days and 30 (IQR: 7-83) days, respectively. CPS and PPI (30 cases) were moderately correlated (r = 0.72, p<0.01). AS and CPS/PPI (30 cases) were significantly correlated (p<0.01) and showed a strong correlation (r = 0.86 and 0.80, respectively). In the 30-day survival prediction, the AUROCs of CPS and PPI (30 cases) were 0.967 (95%CI: 0.919-1) and 0.884 (95%CI: 0.767-1), respectively. Both CPS and PPI (30 cases) showed high accuracy in predicting the 30-day prognosis, with no significant difference (p = 0.077). The AUROC of PPI (59 cases) was 0.840 (95%CI: 0.711-0.969). CONCLUSIONS: AS and CPS/PPI showed significant correlations. The high accuracy of CPS may have been influenced by the fact that multiple head and neck cancer specialists at a comprehensive cancer center estimated CPS. Both CPS and PPI showed high prognostic accuracy in predicting 30-day survival. This suggests that PPI is useful in centers among physicians and healthcare workers unfamiliar with head and neck cancer.

Estimated prevalence and characteristics of bilateral vestibulopathy diagnosed in Japan: A nationwide survey.

OBJECTIVE: To assess the prevalence and annual incidence of bilateral vestibulopathy (BV) diagnosed in the Japanese adult population. METHODS: We conducted a mail-based survey targeting otolaryngologic clinics and hospitals across Japan to estimate the annual number of patients who were diagnosed as having bilateral vestibulopathy after vestibular function tests during a 12-month period ending March 2019. Using a stratified sampling method, we selected 1,106 departments and asked them to report the number of patients with BV and their demographics. The total number of patients was estimated by multiplying the reported numbers by the reciprocal of the sampling rate and response rate. RESULTS: The overall survey response rate was 51.4% (568 departments). The estimated number of patients diagnoses with BV in 2018 was 1,063 (95% confidential interval [CI], 127-1,998) which included 407 patients (95% CI: 134-680) newly-diagnosed with BV. The prevalence and annual incidence of BV in Japan were 0.84 and 0.32, respectively per 100,000 population in Japan. The male-to-female ratio of BV patients was 1.29, and the mean age was 63.7 ± 16.4 years (range 18-84 years). The most frequent etiologies of BV were Meniere's disease (11.4%), meningitis (3.4%), and ototoxic agents (3%). CONCLUSIONS: Patients who were diagnosed as having BV were extremely rare in Japan.

Temporal Adjusters Can Reduce Pain During the Video Head Impulse Test for Patients With Mongoloid Facial Features, Without Increasing the Slippage-Induced Artifacts.

BACKGROUND: The aim of this study was to determine whether the extent and intensity of pain caused by wearing goggles during the video head impulse test (vHIT) could be reduced by adjusting the direction in which the band pulls the goggles, without increasing the number of artifacts recorded during vHIT. METHODS: vHIT tests were performed in 65 healthy adult subjects, and the Visual Analog Scale (VAS) and Numerical Rating Scale (NRS) were used to evaluate pain intensity. Temporal adjusters were used to adjust the direction in which the band pulls the goggles, without decreasing the tightness of the temple straps. Artifacts were compared by calculating the instantaneous gains at 40 ms, 60 ms, and 80 ms of head movement. RESULTS: Maximum VAS and NRS of pain were significantly reduced from 22.0 ± 2.3 to 13.0 ± 1.7 and from 3.0 ± 0.2 to 2.0 ± 0.2 (both P < .0001). The VAS score without adjusters was significantly correlated with the improvement of the VAS score with temporal adjusters (P < .0001, r = 0.61). The higher the VAS score without adjusters, the greater the improvement in the VAS score with temporal adjusters. The instantaneous gains were close to 1.0 under both conditions. CONCLUSION: The pain induced by the goggle was significantly mitigated with temporal adjusters in the bilateral temple strap. Using temporal adjusters is a useful and easy solution to reduce discomfort during vHIT, while maintaining the tightness of the strap to decrease the slippageinduced artifacts.

Two cases of refractory eosinophilic granulomatosis with polyangiitis wherein mepolizumab was effective against pulmonary and ear lesions.

Recently, mepolizumab, an interleukin (IL)-5 inhibitor, has been indicated for the treatment of eosinophilic granulomatosis with polyangiitis (EGPA) refractory to standard therapies. However, no reports have compared the efficacy of mepolizumab according to symptoms and organ lesions. Herein, we report two cases in which mepolizumab was highly effective in the management of EGPA with lung lesions and otitis media refractory to treatment with multiple immunosuppressive agents. These two cases suggest that mepolizumab is effective in treating pulmonary and ear lesions in EGPA.

Unpleasantness of Amplified Environmental Sound Used in Tinnitus Sound Therapy: A Preliminary Study of Clinical Assessment.

OBJECTIVES: In this study, our aim was to use environmental sounds amplified in the frequency region corresponding to the tinnitus frequency of individual patients and apply them as sound therapy in tinnitus retraining therapy (TRT). In this pilot study, we 1) investigated the unpleasantness of processed environmental sounds using the amplification, attenuation, and removal in different frequency regions; 2) compared the unpleasantness of processed sounds for older and younger groups of participants; and 3) determined the amplification level appropriate for a clinical test. MATERIALS AND METHODS: We processed the sound of a river with three types of modification (amplified, attenuated, and notched) at a one-octave width of seven central frequencies, in the range 250-8000 Hz. Amplified and attenuated sounds were processed with five positive gains (+6, +12, +15.6, +18, and +20 dB) and two negative gains (-6 and -12 dB). Twenty-three older participants and 23 younger participants rated the unpleasantness of sounds using a visual analog scale. RESULTS: We found that, in the older group, there was no difference in unpleasantness among the three modifications. Older participants rated the level of unpleasantness as lower than younger participants for processed sounds in the high-frequency region. There were no marked differences among the amplification levels in the group of older participants. CONCLUSION: Based on the results, we decided that our clinical study would target older patients who had a tinnitus frequency over 4000 Hz and would compare the effect of an amplified sound with a 20 dB gain at the frequency corresponding to individual tinnitus with notched sound.

Tricellulin Expression and its Deletion Effects in the Endolymphatic Sac.

OBJECTIVES: Tricellulin is a tight junction (TJ)-forming protein that participates in the sealing function of tricellular TJs. Tricellulin-knockout (Tric-/-) mice show progressive hearing loss with degeneration of hair cells in the cochlea without physiological or physical disorders. In the present study, we investigated the tricellulin expression and its deletion effects in the endolymphatic sac (ES) using Tric-/- mice. MATERIALS AND METHODS: The ES epithelia from wild-type (WT) mice were laser-microdissected, and RT-PCR was performed. The ES sections from Tric-/- and WT mice were immunostained with an anti-tricellulin antibody. Hematoxylin and eosin staining was performed for morphological examination. The inner ear of Tric-/- mice was perfused with biotinylation reagents, and the ES sections were observed for tracer permeability assay after applying streptavidin-Alexa Fluor 488 conjugate. RESULTS: The tricellulin expression was confirmed by RT-PCR and by immunohistochemistry in the WT ES. The ES in Tric-/- mice showed normal morphology and revealed no biotin leakage from the lumen. CONCLUSION: The ES in Tric-/- mice showed no changes in morphology or disruption in macromolecular barrier function. The effects of solute leakages in the ES of Tric-/- mice may be very limited and compensatable, or that the ES epithelia may have other sealing system covering the lack of tricellulin.

The difference in endolymphatic hydrostatic pressure elevation induced by isoproterenol between the ampulla and the cochlea.

OBJECTIVE: The purpose of the study was to investigate the difference in the responses of endolymphatic hydrostatic pressure to isoproterenol, ß-adrenergic receptor agonist, between pars superior and pars inferior. METHODS: The hydrostatic pressure of endolymph and perilymph and endolymphatic potential in the ampulla and the cochlea during the intravenous administration of isoproterenol were recorded using a servo-null system in guinea pigs. RESULTS: The hydrostatic pressure of endolymph and perilymph in the ampulla and cochlea was similar in magnitude. Isoproterenol significantly increased hydrostatic pressure of ampullar and cochlear endolymph and perilymph with no change in the ampullar endolymphatic potential and endocochlear potential, respectively. The isoproterenol-induced maximum change of endolymphatic hydrostatic pressure in ampulla was significantly (p<0.01) smaller than that in the cochlea. In ears with an obstructed endolymphatic sac, the action of isoproterenol on endolymphatic hydrostatic pressure in the ampulla disappeared like that in the cochlea. CONCLUSION: Isoproterenol elevates endolymphatic hydrostatic pressure in different manner between the vestibule and the cochlea.

Hormonal changes following a low-salt diet in patients with Ménière's disease.

OBJECTIVE: A low-salt diet has been the main treatment modality for Ménière's disease (MD) since the 1930s, although the mechanisms behind this therapy have not yet been elucidated. Salt reduction is associated with a physiological increase in plasma aldosterone concentration. Several experimental reports have suggested that aldosterone may increase endolymph absorption in the inner ear, particularly in the endolymphatic sac. Therefore, aldosterone elevations due to a low-salt diet may increase endolymph absorption in the endolymphatic sac. In this study, urinary sodium excretion, plasma aldosterone, and other hormones were measured during low-salt diet therapy in patients with MD. METHODS: We included 13 patients with unilateral definite MD diagnosed at the Kagawa University Hospital. A national registered dietitian provided nutritional guidance initially for 14 enrolled patients with MD and prescribed them a low-salt diet (2g Na/day). Twenty-four hour urine was sampled at baseline, at 2, 4, 6, and 8 weeks, and at 6, 12, 18, and 24 months after initiating the low-salt diet. Urine osmotic pressure, and Na, K, and Cl levels were measured, and 24-h urinary Na, K, and Cl excretion was estimated. Aldosterone, cortisol, hormones (including anti-diuretic hormone), Na, K, and Cl in the blood were measured, alongside plasma osmotic pressure. A total of 13 patients followed the low salt diet therapy for more than 2 years, while one patient dropped out. RESULTS: Group 1 (n=7) included patients with a mean urinary sodium excretion amount lower than 3g/day and Group 2 (n=6) included those with more than 3g/day. Vertiginous states of all Group 1 patients comprised complete control (Class A, 100%), while Group 2 patients included Class A (four patients, 66%), Class C (one patient, 17%), and Class D (one patients, 17%). Plasma aldosterone concentrations significantly increased during the 2-year low-salt diet; concentrations in Group 1 tended to be higher than that in Group 2. Hearing improvements after 2 years in Group 1 were significantly better than that in Group 2. The plasma concentration of the hormones except aldosterone was not significantly changed during 2-year low-salt diet. CONCLUSION: A low-salt diet was an effective treatment for patients with Ménière's disease. This treatment will have a greater effect, when sodium intake is reduced to less than 3g/day. A low-salt diet may induce an increase in the plasma aldosterone concentration that can activate ion transport and absorbing endolymph in the endolymphatic sac.

Ion transport its regulation in the endolymphatic sac: suggestions for clinical aspects of Meniere's disease.

Ion transport and its regulation in the endolymphatic sac (ES) are reviewed on the basis of recent lines of evidence. The morphological and physiological findings demonstrate that epithelial cells in the intermediate portion of the ES are more functional in ion transport than those in the other portions. Several ion channels, ion transporters, ion exchangers, and so on have been reported to be present in epithelial cells of ES intermediate portion. An imaging study has shown that mitochondria-rich cells in the ES intermediate portion have a higher activity of Na+, K+-ATPase and a higher Na+ permeability than other type of cells, implying that molecules related to Na+ transport, such as epithelial sodium channel (ENaC), Na+-K+-2Cl- cotransporter 2 (NKCC2) and thiazide-sensitive Na+-Cl- cotransporter (NCC), may be present in mitochondria-rich cells. Accumulated lines of evidence suggests that Na+ transport is most important in the ES, and that mitochondria-rich cells play crucial roles in Na+ transport in the ES. Several lines of evidence support the hypothesis that aldosterone may regulate Na+ transport in ES, resulting in endolymph volume regulation. The presence of molecules related to acid/base transport, such as H+-ATPase, Na+-H+ exchanger (NHE), pendrin (SLC26A4), Cl--HCO3- exchanger (SLC4A2), and carbonic anhydrase in ES epithelial cells, suggests that acid/base transport is another important one in the ES. Recent basic and clinical studies suggest that aldosterone may be involved in the effect of salt-reduced diet treatment in Meniere's disease.

Usefulness of multislice-CT using multiplanar reconstruction in the preoperative assessment of the ossicular lesions in the middle ear diseases.

OBJECTIVE: The aim of the study is to evaluate the usefulness of multislice computed tomography (MSCT) using multiplanar reconstruction (MPR) in obtaining preoperative information on the ossicular lesions of middle ear diseases by comparing the ossicular findings of MPR images with the operative findings. METHODS: Sixty-two ears and 10 ears with preoperative middle ear diseases underwent 4- and 64-detector row CT of the temporal bone in Kagawa University Hospital, respectively. MPR images of three ossicles were created at the planes parallel to the long axis of ossicles. RESULTS: The findings of the three ossicles in MPR images were compatible with their operative findings in approximately 91% of 72 ears with various middle ear diseases. There was no significant difference in the coincidence rate of both findings between 4- and 64-detector row CT scanners. The ears with no soft tissue shadows around the ossicles had the coincidence rate of 96-100% in each ossicular part, whereas the coincidence rate was lower in the ears with soft tissue shadows around the ossicles. CONCLUSION: MPR imagings of the ossicles provide accurate preoperative information on the ossicular lesions in middle ear diseases. The 4-detector CT is still a useful device for imaging of the ossicles.

Deletion of Tricellulin Causes Progressive Hearing Loss Associated with Degeneration of Cochlear Hair Cells.

Tricellulin (also known as MARVELD2) is considered as a central component of tricellular tight junctions and is distributed among various epithelial tissues. Although mutations in the gene encoding tricellulin are known to cause deafness in humans (DFNB49) and mice, the influence of its systemic deletion in vivo remains unknown. When we generated tricellulin-knockout mice (Tric(-/-)), we found an early-onset rapidly progressive hearing loss associated with the degeneration of hair cells (HCs); however, their body size and overall appearance were normal. Tric(-/-) mice did not show any morphological change pertaining to other organs such as the gastrointestinal tract, liver, kidney, thyroid gland and heart. The endocochlear potential (EP) was normal in Tric(-/-) mice, suggesting that the tight junction barrier is maintained in the stria vascularis, where EP is generated. The degeneration of HCs, which occurred after the maturation of EP, was prevented in the culture medium with an ion concentration similar to that of the perilymph. These data demonstrate the specific requirement of tricellulin for maintaining ion homeostasis around cochlear HCs to ensure their survival. The Tric(-/-) mouse provides a new model for understanding the distinct roles of tricellulin in different epithelial systems as well as in the pathogenesis of DFNB49.

Accelerated hyperfractionated radiotherapy for small cell carcinoma of the nasopharynx.

BACKGROUND: The purpose of this study was to report the treatment outcome of a patient with nasopharyngeal small cell carcinoma. METHODS: The patient received concurrent chemoradiotherapy (CRT). Chemotherapy consisted of 4 cycles of cisplatin and etoposide. Accelerated hyperfractionated radiotherapy (RT) was performed with a dose of 45 Gy in 30 fractions over 3 weeks for the nasopharynx and upper neck region, whereas conventional fractionated RT was performed with a dose of 50 Gy in 25 fractions over 5 weeks for the lower neck region. RESULTS: Complete response was achieved 1 month after the completion of CRT. Prophylactic cranial irradiation was not performed. Isolated brain metastasis was diagnosed 18 months after the completion of CRT. Finally, the patient died because of the brain and cord metastases 32 months after the completion of CRT. CONCLUSION: The administration of prophylactic cranial irradiation may be considered for nasopharyngeal small cell carcinoma.

Clinical outcomes of nedaplatin and S-1 treatment with concurrent radiotherapy in advanced head and neck cancer.

CONCLUSION: Nedaplatin and S-1 treatment with concurrent radiotherapy was effective, with acceptable toxicities. This regimen does not require extensive intravenous hydration and continuous infusion. Nedaplatin and S-1 may contribute to better clinical outcomes and improve quality of life for patients. OBJECTIVES: We retrospectively analyzed the clinical efficacy and toxicity of concurrent chemoradiotherapy with nedaplatin and S-1 for head and neck squamous cell cancer. METHODS: Forty-six patients with oropharyngeal, hypopharyngeal, and laryngeal cancer were treated with S-1 on days 1 through 14 and nedaplatin on day 1 every 4 weeks for two cycles of radiotherapy. Therapeutic responses and adverse events were assessed. RESULTS: Primary site tumors and neck lymph nodes exhibited complete response rates of 91% and 64.3%, respectively. The 4-year relapse-free survival and overall survival rates were 76.2% and 85.3%, respectively. The main grade 3 and 4 toxicities were mucositis (30%), leukopenia (30%), anorexia (22%), dermatitis (15%), and thrombocytopenia (9%).

Prox1 expression in the endolymphatic sac revealed by whole-mount fluorescent imaging of Prox1-GFP transgenic mice.

This study describes a technical breakthrough in endolymphatic sac research, made possible by the use of the recently generated Prox1-GFP transgenic mouse model. Whole-mount imaging techniques through the decalcified temporal bone and three-dimensional observations of Prox1-GFP mouse tissue revealed the positive labeling of the endolymphatic sac in adult stage, and allowed, for the first time, the GFP-based identification of endolymphatic sac epithelial cells. Prox1 expression was observed in all parts of the endolymphatic sac epithelia. In intermediate portion of the endolymphatic sac, mitochondria-rich cells did not express Prox1, although ribosome-rich cells showed strong GFP labeling. The anatomical relationship between the endolymphatic sac and the surrounding vasculature was directly observed. In the endolymphatic sac, expression of Prox1 may suggest progenitor cell-like pluripotency or developmental similarity to systemic lymphatic vessels in other organs. This whole-mount imaging technique of the endolymphatic sac can be combined with other conventional histological, sectioning, and labeling techniques and will be very useful for future endolymphatic sac research.

Cystic fibrosis transmembrane conductance regulator in the endolymphatic sac of the rat.

OBJECTIVE: Na(+) and Cl(-) are dominant ions in the endolymphatic fluid in the endolymphatic sac and are important for volume regulation in the endolymphatic sac. An epithelial sodium channel (ENaC) and other Na(+) transporters have been identified in the endolymphatic sac epithelia, and they are involved in the regulation of endolymph. Although the presence of Cl(-) channels in the endolymphatic sac epithelia has been speculated, no Cl(-) channels have been identified. In this study, we confirmed the expression of cystic fibrosis transmembrane conductance regulator (CFTR) in the endolymphatic sac by reverse transcriptase polymerase chain reaction (RT-PCR) and by immunohistochemical staining. METHODS: Pure mRNA from endolymphatic sac epithelia was prepared using laser capture microdissection (LCM) and examined using RT-PCR. Localization of CFTR and ENaC in the endolymphatic sac was examined using immunohistochemistry. RESULTS: mRNA of the CFTR was expressed in the endolymphatic sac. Immunohistochemical analysis showed the expression of the CFTR on apical side of the endolymphatic sac epithelia and co-localization with the ENaC. CONCLUSION: RT-PCR and immunohistochemistry were used to identify the expression of CFTR in the endolymphatic sac epithelia, which gives us a clue for understanding Cl(-) transport in the endolymphatic sac. These results suggest a pathway for Cl(-), possibly through interaction with the ENaC, which may regulate the endolymph in the endolymphatic sac.

Localization and proliferation of lymphatic vessels in the tympanic membrane in normal state and regeneration.

We clarified the localization of lymphatic vessels in the tympanic membrane and proliferation of lymphatic vessels during regeneration after perforation of the tympanic membrane by using whole-mount imaging of the tympanic membrane of Prox1 GFP mice. In the pars tensa, lymphatic vessel loops surrounded the malleus handle and annulus tympanicus. Apart from these locations, lymphatic vessel loops were not observed in the pars tensa in the normal tympanic membrane. Lymphatic vessel loops surrounding the malleus handle were connected to the lymphatic vessel loops in the pars flaccida and around the tensor tympani muscle. Many lymphatic vessel loops were detected in the pars flaccida. After perforation of the tympanic membrane, abundant lymphatic regeneration was observed in the pars tensa, and these regenerated lymphatic vessels extended from the lymphatic vessels surrounding the malleus at day 7. These results suggest that site-specific lymphatic vessels play an important role in the tympanic membrane.