Susceptibility of mouse cochlear hair cells to cisplatin ototoxicity largely depends on sensory mechanoelectrical transduction channels both Ex Vivo and In Vivo.

Cisplatin, a highly effective chemotherapeutic drug for various human cancers, induces irreversible sensorineural hearing loss as a side effect. Currently there are no highly effective clinical strategies for the prevention of cisplatin-induced ototoxicity. Previous studies have indicated that short-term cisplatin ototoxicity primarily affects the outer hair cells of the cochlea. Therefore, preventing the entry of cisplatin into hair cells may be a promising strategy to prevent cisplatin ototoxicity. This study aimed to investigate the entry route of cisplatin into mouse cochlear hair cells. The competitive inhibitor of organic cation transporter 2 (OCT2), cimetidine, and the sensory mechanoelectrical transduction (MET) channel blocker benzamil, demonstrated a protective effect against cisplatin toxicity in hair cells in cochlear explants. Sensory MET-deficient hair cells explanted from Tmc1Δ;Tmc2Δ mice were resistant to cisplatin toxicity. Cimetidine showed an additive protective effect against cisplatin toxicity in sensory MET-deficient hair cells. However, in the apical turn, cimetidine, benzamil, or genetic ablation of sensory MET channels showed limited protective effects, implying the presence of other entry routes for cisplatin to enter the hair cells in the apical turn. Systemic administration of cimetidine failed to protect cochlear hair cells from ototoxicity caused by systemically administered cisplatin. Notably, outer hair cells in MET-deficient mice exhibited no apparent deterioration after systemic administration of cisplatin, whereas the outer hair cells in wild-type mice showed remarkable deterioration. The susceptibility of mouse cochlear hair cells to cisplatin ototoxicity largely depends on the sensory MET channel both ex vivo and in vivo. This result justifies the development of new pharmaceuticals, such as a specific antagonists for sensory MET channels or custom-designed cisplatin analogs which are impermeable to sensory MET channels.

Advanced Magnetic Resonance Imaging Sheds Light on the Distinct Pathophysiology of Various Types of Acute Sensorineural Hearing Loss.

OBJECTIVE: To compare the findings of magnetic resonance imaging (MRI) with advanced protocols in patients with various types of acute sensorineural hearing loss (ASNHL). STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Two hundred eighty-seven patients with ASNHL. INTERVENTIONS: All patients underwent MRI scanning, including heavily T2-weighted three-dimensional fluid-attenuated inversion recovery before and 4 hours after the intravenous administration of gadolinium contrast medium (delayed 3D-FLAIR). A hybrid of the reversed image of the positive endolymph signal and the native image of the perilymph signal image was constructed to visualize the endolymphatic space. RESULTS: The detection rates of abnormal MRI findings vary significantly among different types of ASNHL. A hyperintense signal on delayed 3D-FLAIR was observed in all patients with intralabyrinthine schwannoma or vestibular schwannoma and 20.5% of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) but was rarely observed in definite Ménière's disease (MD, 2.6%). In contrast, endolymphatic hydrops (EH) was frequently observed in patients with definite MD (79.5%) but was observed much less frequently in patients with ISSNHL (11.0%). In patients with cochlear MD and ALHL, detection rates of cochlear EH were similar to those with definite MD, whereas detection rates of vestibular EH were significantly lower than in patients with definite MD. CONCLUSIONS: The significantly different detection rates of abnormal MRI findings among various types of ASNHL shed light on the distinct pathophysiology of each disorder. A diagnosis based on MRI findings with advanced protocols may help select treatment strategies and provide prognostic information for patients.

Slc26a4 expression prevents fluctuation of hearing in a mouse model of large vestibular aqueduct syndrome.

SLC26A4 mutations cause fluctuating and progressive hearing loss associated with enlargement of the vestibular aqueduct (EVA). SLC26A4 encodes a transmembrane anion exchanger called pendrin expressed in nonsensory epithelial cells of the lateral wall of cochlea, vestibular organs and endolymphatic sac. We previously described a transgenic mouse model of EVA with doxycycline (dox)-inducible expression of Slc26a4 in which administration of dox from conception to embryonic day 17.5 (DE17.5) resulted in hearing fluctuation between 1 and 3months of age. In the present study, we hypothesized that Slc26a4 is required to stabilize hearing in DE17.5 ears between 1 and 3months of age. We tested our hypothesis by evaluating the effect of postnatal re-induction of Slc26a4 expression on hearing. Readministration of dox to DE17.5 mice at postnatal day 6 (P6), but not at 1month of age, resulted in reduced click-evoked auditory brainstem response (ABR) thresholds, less fluctuation of hearing and a higher surface density of pendrin expression in spindle-shaped cells of the stria vascularis. Pendrin expression in spindle-shaped cells was inversely correlated with ABR thresholds. These findings suggest that stabilization of hearing by readministration of dox at P6 is mediated by pendrin expression in spindle-shaped cells. We conclude that early re-induction of Slc26a4 expression can prevent fluctuation of hearing in our Slc26a4-insufficient mouse model. Restoration of SLC26A4 expression and function could reduce or prevent fluctuation of hearing in EVA patients.

Two Novel Diphenolic Metabolites from the Inedible Mushroom Thelephora palmata.

During the search for bioactive secondary metabolites, thelepalmatins A and B (1 and 2) were isolated from the fresh fruiting bodies of Thelephra palmata, together with four known compounds (3-6). Their structures were elucidated using MS analyses, and extensive 2D-heteronuclear NMR data interpretation. Compounds 3, 4 and 6 showed antimicrobial activities against Staphylococcus aureus and Bacillus subtilis with MIC values of 21.7-70.4 µM.

ILDR1 null mice, a model of human deafness DFNB42, show structural aberrations of tricellular tight junctions and degeneration of auditory hair cells.

In the mammalian inner ear, bicellular and tricellular tight junctions (tTJs) seal the paracellular space between epithelial cells. Tricellulin and immunoglobulin-like (Ig-like) domain containing receptor 1 (ILDR1, also referred to as angulin-2) localize to tTJs of the sensory and non-sensory epithelia in the organ of Corti and vestibular end organs. Recessive mutations of TRIC (DFNB49) encoding tricellulin and ILDR1 (DFNB42) cause human nonsyndromic deafness. However, the pathophysiology of DFNB42 deafness remains unknown. ILDR1 was recently reported to be a lipoprotein receptor mediating the secretion of the fat-stimulated cholecystokinin (CCK) hormone in the small intestine, while ILDR1 in EpH4 mouse mammary epithelial cells in vitro was shown to recruit tricellulin to tTJs. Here we show that two different mouse Ildr1 mutant alleles have early-onset severe deafness associated with a rapid degeneration of cochlear hair cells (HCs) but have a normal endocochlear potential. ILDR1 is not required for recruitment of tricellulin to tTJs in the cochlea in vivo; however, tricellulin becomes mislocalized in the inner ear sensory epithelia of ILDR1 null mice after the first postnatal week. As revealed by freeze-fracture electron microscopy, ILDR1 contributes to the ultrastructure of inner ear tTJs. Taken together, our data provide insight into the pathophysiology of human DFNB42 deafness and demonstrate that ILDR1 is crucial for normal hearing by maintaining the structural and functional integrity of tTJs, which are critical for the survival of auditory neurosensory HCs.

Ex vivo visualization of the mouse otoconial layer compared with micro-computed tomography.

HYPOTHESIS: Micro-computed tomography (micro-CT) is useful for assessing the 3-dimensional (3D) morphology and age-related changes of the otoconial layer. BACKGROUND: Wriggle mouse Sagami (WMS) is a mutant of the plasma membrane Ca2+ ATPase type2 gene (Atp2b2) with deficits in the saccular otoconia. We examined the effectiveness of micro-CT in evaluating the otoconial layer of WMS and C57BL/6J mice. METHODS: Otic capsules of C57BL/6J mice at different fixation time were examined using micro-CT to evaluate the effects of the fixation time on the otoconial layer. Otic capsules of Atp2b2(wri/wri), Atp2b2(wri/+), and Atp2b2(+/+) mice at P14, P21, and the age of 3 months were used to analyze age-related changes in the otoconial layer. A series of cross-section and 3D reconstructed images of the otoconial layer were obtained. The micro-CT findings were compared with the otic capsule findings cleared in methyl salicylate using stereomicroscopy. RESULTS: Micro-CT produced high-resolution images of the otoconial layer, thereby providing information regarding the spatial configuration and 3D curvature. There were no changes between the different fixation times. In the Atp2b2(wri/+) and Atp2b2(+/+) mice, the saccular and utricular otoconial layers were normal among all age groups. In the Atp2b2(wri/wri) mice, the saccular otoconial layer decreased on P14 and was absent on P21, whereas the utricular otoconial layer disappeared at 3 months of age. CONCLUSION: We obtained precise information regarding the mouse otoconial layer with minimum artifacts. This method is expected to improve our understanding of the physiologic function and age-related changes in otolith organs.

Audiovestibular findings in patients with Vogt-Koyanagi-Harada disease.

CONCLUSION: The long-term follow-up study revealed a good audiovestibular prognosis in our patients with Vogt-Koyanagi-Harada disease (VKH) after adequate treatment. OBJECTIVES: To evaluate the audiovestibular findings and long-term prognosis of patients with VKH. METHODS: A total of 82 ears in 41 patients (9 males and 32 females, aged 18-78 years) with VKH were examined in the audiovestibular study. Of the 41 patients, 16 patients with follow-up periods of more than 12 months (13-158 months) were included in the long-term follow-up study. Audiovestibular examinations included pure-tone audiometry; positional, positioning, and spontaneous nystagmus tests; and a caloric test. RESULTS: Among the 41 patients, 28 (68%) complained of auditory symptoms at the initial visit and 28 (68%) showed sensorineural hearing loss (SNHL). Of the 24 patients who underwent nystagmus tests, only 3 (13%) presented with vestibular symptoms whereas 11 (46%) had nystagmus. Among 32 ears in 16 patients enrolled in the long-term follow-up study, 19 ears showed SNHL at the initial visit. The SNHL returned to normal in 14 ears (74%) and remained minimal in severity in the other 5 ears (26%) at the last visit. None of the patients showed persistent or repetitive vestibular symptoms.

A DFNA5 mutation identified in Japanese families with autosomal dominant hereditary hearing loss.

Mutations in DFNA5 lead to autosomal dominant nonsyndromic hereditary hearing loss (NSHHL). To date, four different mutations in DFNA5 have been reported to cause hearing loss. A 3 bp deletion mutation (c.991-15_991-13del) was identified in Chinese and Korean families with autosomal dominant NSHHL, which suggested that the 3 bp deletion mutation was derived from a single origin. In the present study, we performed genetic screening of mutations in the interval between intron 6 and exon 9 of DFNA5 in 65 Japanese patients with autosomal dominant NSHHL and identified the c.991-15_991-13del mutation in two patients. Furthermore, we compared the DFNA5-linked haplotypes consisting of intragenic SNPs between the reported Chinese and Korean families and found that the Japanese patients showed a shared region spanning 41,874 bp. This is the first report of DFNA5 mutations in Japanese patients with autosomal dominant NSHHL, supporting the suggestion that the 3 bp deletion mutation occurred in their ancestors.

[Treatments for otorhinolaryngological patients with psychiatric disorders].

There are few systems in place for patients with psychiatric disorders who need treatments for physical complications. In Tokyo, "The Tokyo metropolitan psychiatric emergency system" was established in 1981, and Ome Municipal General Hospital participated in it. Under this system, fifteen patients with psychiatric disorders were treated for otorhinolaryngological diseases in our department from April 2005 to March 2011. We reviewed the fifteen patients. The coexisting psychiatric disorders were schizophrenia in twelve patients, and mental retardation, Korsakoff's syndrome, and Alzheimer's dementia in one patient each, respectively. All the patients had been receiving psychiatric treatment. The otorhinolaryngological diseases were head and neck cancer in nine patients, chronic sinusitis in three patients, and benign salivary gland tumor, cholesteatoma, and epistaxis in one patient each, respectively. Among the fifteen patients, thirteen could complete their treatment, but two dropped out due to exacerbation of their psychiatric symptoms. The therapeutic course is uncertain in otorhinolaryngological diseases occurring concomitantly with psychiatric disorders, especially in head and neck cancer, because it may be difficult to prioritize the problem when determining the treatment options and delivering the treatment. Thus, we should treat patients with psychiatric disorders carefully on a case-by-case basis depending on their psychiatric symptoms. It is also important to cooperate with psychiatrists and patients' families.

DNA microarray analysis of transcriptional responses of rats housed on solid and grid cage flooring.

We performed DNA microarray analysis on the white blood cells (WBCs) of rats housed on solid and grid cage flooring. The expression levels of 50 genes were found to increase more than 2-fold in the WBCs on grid cage flooring, including many genes encoding proteins involved in inflammatory or immune responses. It is therefore suggested that the health and welfare of laboratory rats is likely to be improved by housing rats on solid floors.

Nicorandil prevents Gαq-induced progressive heart failure and ventricular arrhythmias in transgenic mice.

BACKGROUND: Beneficial effects of nicorandil on the treatment of hypertensive heart failure (HF) and ischemic heart disease have been suggested. However, whether nicorandil has inhibitory effects on HF and ventricular arrhythmias caused by the activation of G protein alpha q (Gα(q)) -coupled receptor (GPCR) signaling still remains unknown. We investigated these inhibitory effects of nicorandil in transgenic mice with transient cardiac expression of activated Gα(q) (Gα(q)-TG). METHODOLOGY/PRINCIPAL FINDINGS: Nicorandil (6 mg/kg/day) or vehicle was chronically administered to Gα(q)-TG from 8 to 32 weeks of age, and all experiments were performed in mice at the age of 32 weeks. Chronic nicorandil administration prevented the severe reduction of left ventricular fractional shortening and inhibited ventricular interstitial fibrosis in Gα(q)-TG. SUR-2B and SERCA2 gene expression was decreased in vehicle-treated Gα(q)-TG but not in nicorandil-treated Gα(q)-TG. eNOS gene expression was also increased in nicorandil-treated Gα(q)-TG compared with vehicle-treated Gα(q)-TG. Electrocardiogram demonstrated that premature ventricular contraction (PVC) was frequently (more than 20 beats/min) observed in 7 of 10 vehicle-treated Gα(q)-TG but in none of 10 nicorandil-treated Gα(q)-TG. The QT interval was significantly shorter in nicorandil-treated Gα(q)-TG than vehicle-treated Gα(q)-TG. Acute nicorandil administration shortened ventricular monophasic action potential duration and reduced the number of PVCs in Langendorff-perfused Gα(q)-TG mouse hearts. Moreover, HMR1098, a blocker of cardiac sarcolemmal K(ATP) channels, significantly attenuated the shortening of MAP duration induced by nicorandil in the Gα(q)-TG heart. CONCLUSIONS/SIGNIFICANCE: These findings suggest that nicorandil can prevent the development of HF and ventricular arrhythmia caused by the activation of GPCR signaling through the shortening of the QT interval, action potential duration, the normalization of SERCA2 gene expression. Nicorandil may also improve the impaired coronary circulation during HF.

Longitudinal study of 29 patients with Meniere's disease with follow-up of 10 years or more (In commemoration of Professor Emeritus Isamu Watanabe).

CONCLUSIONS: A final incidence of bilateral involvement was 20.7%. Episodic spells of vertigo were completely controlled in 23 of 29 patients, while 11 of 29 patients demonstrated over 70 dB hearing loss. OBJECTIVE: To analyze the clinical course of 29 patients with Meniere's disease during follow-up of 10 years or more. METHODS: The subjects were 29 patients with a mean follow-up of 18.3 years. The hearing level was measured by the pure tone average (PTA) of four frequencies at the initial and the final examination, and it was classified into four categories according to the American Academy of Otolaryngology-Head and Neck Society (AAO-HNS) criteria. The control of vertigo was evaluated by the modified AAO-HNS criteria. RESULTS: At enrolment two patients had bilateral involvement. In the period of follow-up, bilateral involvement emerged in four more patients. The hearing levels at the final examinations were as follows: 3 patients, <25 dB; 6 patients, 26-40 dB; 9 patients, 41-70 dB; and 11 patients, >70 dB. The control of vertigo according to the modified AAO-HNS guideline was class A in 23 patients, class B in 2 patients, and class C in 1 patient; the remaining 3 patients could not be evaluated.

Genes for difference in eosinophilic phenotype between MES and BN.MES-Cyba(mes) rats are on chromosomes 9, 5, and 1.

The Matsumoto Eosinophilia Shinshu (MES) rat strain develops hereditary blood eosinophilia due to the mutant Cyba(mes) gene. In contrast, BN.MES-Cyba(mes) congenic rats, in which the mutant Cyba(mes) gene introduced into the background of the BN strain, have a normal blood eosinophil level despite showing robust proliferation of eosinophils in the bone marrow. However, the congenic rats manifest focal necrosis with eosinophilic infiltration in the liver, a phenotype rarely observed in the original MES rat strain. To elucidate the genetic basis for the strain differences, (MES × BN.MES-Cyba(mes))F(2) rats were bred, and genetic analyses of phenotypes for eosinophilia were performed. Blood and bone marrow eosinophil levels in the F(2) rats showed broad distributions, suggesting that the traits were under the influence of multiple genes. Genetic association studies revealed that BN-derived marker loci on chromosomes 9 and 5 were responsible for the increase in eosinophil level in the bone marrow, decrease in blood eosinophil level, and the induction of focal necrosis with eosinophilic infiltration in the liver. The BN-derived allele of the marker gene on chromosome 1 was responsible for the decrease of both bone marrow and blood eosinophil levels. These data suggest the existence of genes characterizing/distinguishing the eosinophilic phenotypes of MES and BN.MES-Cyba(mes) on these chromosomes, and form the basis for positional cloning studies of the genes. These studies will advance the understanding of the mechanisms involved in eosinophil mobilization from the bone marrow and recruitment to the organs.

Audiovestibular findings in a branchio-oto syndrome patient with a SIX1 mutation.

CONCLUSION: A reported mutation in SIX1 was identified in a patient with familial hearing loss (HL), a left preauricular pit, and bilateral enlarged vestibular aqueducts (EVA). Although the characteristic symptoms of EVA including fluctuating HL and repetitive vertigo were not seen in the patient, further studies are needed to clarify the association between EVA and such symptoms. OBJECTIVES: To study the audiovestibular functions, and to identify the causative gene in a patient with branchio-oto syndrome. METHODS: We enrolled a 30-year-old female in whom HL was pointed out at the age of 6 years. She visited our department at the age of 21 years, and had not experienced any progression of her HL, tinnitus, or vertigo. Pure-tone audiograms showed bilateral moderate mixed HL with no apparent progression during a 9-year follow-up period. Audiovestibular examinations included distortion product otoacoustic emissions (DPOAEs), electrocochleography (ECochG), and electronystagmography (ENG). Direct sequencing was utilized to screen for SIX1, EYA1, SLC26A4, GJB2, and mitochondrial DNA MTRNR1 including 1555 position. RESULTS: The findings of DPOAEs, ECochG, and ENG indicated cochlear HL with no vestibular dysfunction. A previously reported mutation of a heterozygous c.386A > G (p.Y129C) in SIX1 was detected. No mutation was identified in EYA1, SLC26A4, GJB2, or MTRNR1.

BN.MES-Cyba(mes) congenic rats manifest focal necrosis with eosinophilic infiltration in the liver without blood eosinophilia.

The Matsumoto Eosinophilia Shinshu (MES) rat strain develops hereditary blood eosinophilia and eosinophil-related inflammatory lesions in organs due to the mutant Cyba(mes) gene. We hypothesized that a new eosinophilia model with a different phenotype could be established by changing the genetic background of rats. We bred and characterized a congenic strain, in which the mutant Cyba(mes) gene was introduced into the background of a BN strain (BN.MES-Cyba(mes)). The congenic rats showed robust proliferation of eosinophils in the bone marrow. Nonetheless, blood eosinophil levels of the rats remained within the normal range. In addition, the rats manifested focal necrosis with eosinophilic infiltration in the liver, a phenotype rarely observed in the original MES rat strain. These results imply the presence of genetic polymorphisms between MES and BN strains which modulate the mobilization of eosinophils to the peripheral circulation and organs. The newly established BN.MES-Cyba(mes) congenic rat strain, together with the original MES strain, will provide useful models for elucidating the molecular genetic mechanisms involved in the development and trafficking of eosinophils.

Pivotal Advance: Eosinophilia in the MES rat strain is caused by a loss-of-function mutation in the gene for cytochrome b(-245), alpha polypeptide (Cyba).

MES is a rat strain that spontaneously develops severe blood eosinophilia as a hereditary trait. Herein, we report that eosinophilia in MES rats is caused by a loss-of-function mutation in the gene for cytochrome b(-245), alpha polypeptide (Cyba; also known as p22(phox)), which is an essential component of the superoxide-generating NADPH oxidase complex. The MES rat has a deletion of four nucleotides, including the 5' splice donor GpT of intron 4 of the Cyba gene. As a consequence of the deletion, a 51-nucleotide sequence of intron 4 is incorporated into the Cyba transcripts. Leukocytes from the MES strain lack both CYBA protein and NADPH oxidase activity. Nevertheless, unlike patients with chronic granulomatous disease, who suffer from infections with pathogens due to similar genetic defects in NADPH oxidase, MES rats retain normal innate immune defense against Staphylococcus aureus infection. This is due to large quantities of peritoneal eosinophils in MES rats, which phagocytose and kill the bacteria. MES rat has a balance defect due to impaired formation of otoconia in the utricles and saccules. Eosinophilia of the MES rat was normalized by introduction of a normal Cyba transgene. The mechanisms by which impairment of NADPH oxidase leads to eosinophilia in the MES rat are elusive. However, our study highlights the essential role of NADPH oxidase in homeostatic regulation of innate immunity beyond conventional microbicidial functions.

Primary administration of Lactobacillus johnsonii NCC533 in weaning period suppresses the elevation of proinflammatory cytokines and CD86 gene expressions in skin lesions in NC/Nga mice.

The administration of probiotic lactic acid bacteria (LAB) has been studied for its potential to prevent atopic dermatitis (AD). The objective of this study was to assess the inhibitory mechanism of a skin lesion by LAB using an experimental model that we previously demonstrated in NC/Nga mice. Lactobacillus johnsonii NCC533 (La1) was administered orally to the La1 group from 20 to 22 days after birth, while phosphate-buffered saline was given to the control group. After the induction of skin lesions in 6-week-old mice, the expression of genes supposedly involved in AD was evaluated. Gene expression of the proinflammatory cytokines [interleukin-8 (IL-8), IL-12 and IL-23] was significantly enhanced in the lesional skin of the control group by the induction of the lesion, whereas gene expression of those in the La1 group was not elevated. Interestingly, expression of the costimulatory molecule CD86 showed a pattern similar to the expression of the cytokines in the lesional skin. Moreover, the La1 group showed a significantly lower gene expression of CD86 in Peyer's patches and mesenteric lymph nodes than the control group. The suppression of proinflammatory cytokines and CD86 by primary administration of La1 may significantly contribute to the inhibitory effect on the skin lesion.