Comparison of frequency-specific hearing outcomes after endoscopic and microscopic tympanoplasty.

BACKGROUND: Hearing results of endoscopic and microscopic tympanoplasty have been compared using the average pure tone threshold which could conceal subtle differences at a specific frequency. OBJECTIVES: To compare frequency-specific hearing outcomes of endoscopic and microscopic tympanoplasty. MATERIAL AND METHODS: The study included 42 patients who underwent endoscopic or microscopic type I tympanoplasty. The medical charts of these patients were reviewed retrospectively. We evaluated the pure tone audiometry at 250, 500, 1000, 2000 and 4000 Hz, including bone conduction (BC), air conduction (AC) and air-bone gap (ABG) before and after the surgery. The main outcome measures were frequency-specific pre- and post-operative hearing thresholds and the corresponding changes. We also assessed the graft success rate and surgical complications. RESULTS: BC revealed a significant aggravation at 4000 Hz in microscopic tympanoplasty group, but no significant differences between the two groups at any frequencies. Both groups showed improvements in AC and ABG at all frequencies, without significant differences between the two groups at any single frequency. The maximum improvement of AC and ABG was found at 250 Hz. The graft success rate and operative complications were also similar. CONCLUSIONS AND SIGNIFICANCE: The frequency-specific hearing outcomes of endoscopic and microscopic tympanoplasty are similar.

Acid stimulation-induced semi-pluripotent characteristics in human somatic cells.

BACKGROUND: Clinical trials of cell-based therapies using induced pluripotent stem (iPS) cells have already been started for several neurological diseases. OBJECTIVE: The purpose of the present study was to explore the characteristics and differentiation of somatic cells in vitro undergoing a low pH treatment, so as to provide new therapeutic strategies for treating sensorineural hearing loss. METHODS: Somatic cells were treated with low pH solution to alter their characteristics. In addition, a mouse model of the cochlear lesion was constructed using bilirubin. Subsequently, the characteristics and therapeutic effect of somatic cells undergoing low pH treatment were examined by morphology, alkaline phosphatase (AKP) activity, immunofluorescence assay and q-PCR. RESULTS: The cells in the experimental group grew better than those in the control group. The AKP activity in the experimental group was higher than that in the control group. The expression of Nanog and Oct4 was both positive in the two groups. When the cells were changed to neurobasal medium, the marker of nestin was positive. CONCLUSION: The human somatic cells undergoing a low pH treatment showed the similar characteristics as those of iPS cells, although the functions and therapeutic effect of these altered human somatic cells need to be further studied.

Aging and the peripheral vestibular system.

Whereas much has been learned about age-related auditory changes in the inner ear, relatively little is known about the aging effects on the vestibular part of the inner ear-the peripheral vestibular system. Here we review relevant literature with regard to the prevalence of vestibular dysfunction, vestibular functional and structural changes in the elderly. The prevalence of vestibular dysfunction increases with age. Functionally, as age increases, VEMP amplitudes decrease, VEMP thresholds increase, VOR gain of HIT decreases. Due to the complexity of the vestibular system, variations in subject age and measurement techniques, findings in VEMP latency and caloric tests are conflicting. To address this, a direct measure of the peripheral vestibular system should be applied. Structurally, age-related loss in vestibular ganglion and otoconia have been noted; hair cell changes are not well defined; while subcellular changes remain to be explored. Defining how the onset of vestibular dysfunction correlates with structural degeneration will offer insights into the mechanisms underlying vestibular aging.

Molecular mechanisms underlying the protective effects of hydrogen-saturated saline on noise-induced hearing loss.

OBJECTIVES: This study aimed to explore the molecular mechanism of the protective effects of hydrogen-saturated saline on NIHL. METHODS: Guinea pigs were divided into three groups: hydrogen-saturated saline; normal saline; and control. For saline administration, the guinea pigs were given daily abdominal injections 3 d before and 1 h before noise exposure. ABR were tested to examine cochlear physiology changes. The changes of 8-hydroxy-desoxyguanosine (8-HOdG), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), intercellular cell adhesion molecule-1 (ICAM-1) and high mobility group box-1 protein (HMGB1) in the cochlea were also examined. RESULTS: The results showed that pre-treatment with hydrogen-saturated saline could significantly attenuate noise-induced hearing loss. The concentration of 8-HOdG was also significantly decreased in the hydrogen-saturated saline group compared with the normal saline group. After noise exposure, the concentrations of IL-1, IL-6, TNF-α, and ICAM-1 in the cochlea of guinea pigs in the hydrogen-saturated saline group were dramatically reduced compared to those in the normal saline group. The concentrations of HMGB-1 and IL-10 in the hydrogen-saturated saline group were significantly higher than in those in the normal saline group immediately and at 7 d after noise exposure. CONCLUSIONS: This study revealed for the first time the protective effects of hydrogen-saturated saline on noise-induced hearing loss (NIHL) are related to both the anti-oxidative activity and anti-inflammatory activity.

A de novo silencer causes elimination of MITF-M expression and profound hearing loss in pigs.

BACKGROUND: Genesis of novel gene regulatory modules is largely responsible for morphological and functional evolution. De novo generation of novel cis-regulatory elements (CREs) is much rarer than genomic events that alter existing CREs such as transposition, promoter switching or co-option. Only one case of de novo generation has been reported to date, in fish and without involvement of phenotype alteration. Yet, this event likely occurs in other animals and helps drive genetic/phenotypic variation. RESULTS: Using a porcine model of spontaneous hearing loss not previously characterized we performed gene mapping and mutation screening to determine the genetic foundation of the phenotype. We identified a mutation in the non-regulatory region of the melanocyte-specific promoter of microphthalmia-associated transcription factor (MITF) gene that generated a novel silencer. The consequent elimination of expression of the MITF-M isoform led to early degeneration of the intermediate cells of the cochlear stria vascularis and profound hearing loss, as well as depigmentation, all of which resemble the typical phenotype of Waardenburg syndrome in humans. The mutation exclusively affected MITF-M and no other isoforms. The essential function of Mitf-m in hearing development was further validated using a knock-out mouse model. CONCLUSIONS: Elimination of the MITF-M isoform alone is sufficient to cause deafness and depigmentation. To our knowledge, this study provides the first evidence of a de novo CRE in mammals that produces a systemic functional effect.

Transplantation of human umbilical cord mesenchymal stem cells in cochlea to repair sensorineural hearing.

To examine if transplantation of human umbilical cord mesenchymal stem cells (UMSC) into cochlea can be used to repair sensorineural hearing. Here we transplanted the fifth and sixth generations of UMSCs through the subarachnoid cavity of congenital deaf albino pigs. Auditory brainstem responses (ABR) were measured before and after UMSC transplantation. Cochlear samples were collected at 2 hrs, 3 days, 1, 2, 3, 4 and 8 weeks after transplantation. Immunohistochemistry was used to detect the proliferated cell nuclear antigen (PCNA). The UMSCs were found in different regions of the cochlea, including the stria vascularis, the basal membrane and the spiral ganglions, 3 days to 4 weeks after the transplantation. UMSCs and their DNA were found also in the areas of the brain, the heart, the liver, the kidney and the lung. ABR tests displayed a new waveform in the congenital deaf albino pigs after the UMSCs transplantation. We conclude that human UMSCs injected into the subarachnoid space can migrate into the inner ear, the central nervous system and the periphery organs. The presence of UMSCs in the cochlea maybe associated with changes of ABR waveforms in the congenital deaf albino pigs.

[Meta-analysis on autogenous fat injection for unilateral vocal cord paralysis].

OBJECTIVE: This study conduct a qualitative synthesis and quantitative meta-analysis of VFAFI, aimed to study whether it is a useful treatment for UVCP. METHOD: Electronic databases PubMed, YZ365. COM, WANFANG DATA, CMJD, CHKD,CNKI were searched using relevant keywords. Reported treatment outcomes were clustered into three categories,i. e. subjective, perceptual,acoustic,aerodynamic,and stroboscopic. Meta-analyses were performed on studies with numerical results using random effects model. RESULT: Five articles were identified with a total of 404 patients. All the studies reported significant improvements or decrease after VFAFI in each category of outcome measurements. Meta-analysis demonstrated a significant increase or decrease in all categories. Adverse effects include slight inflammatory reponse can resolve spontaneously within 1 month. The recurrence rate after VFAFI was high due to the self absorption. NNE and Jitter of post-operation is lower than pre-operation,there is no significantly change between the control group and experimental group; F0, Shimmer and MPT of post-operation is higher than pre-operation, there is no significantly change between the control group and experimental group. CONCLUSION: The invasiveness and morbidity of VFAFI are low and the side effects are self-limited. Meta-analyses demonstrated significant improvements or decreased from both objective and subjective measurements. Further controlled studies with longer follow-up periods and more person were included may evaluate the effectiveness of VFAFI more reliably.

[Meta-analysis on effectiveness of prelingually deaf patients at different ages following cochlear implantation].

OBJECTIVE: To assess the clinical effeetiveness of prelingually deaf children after cochlear implantation at different ages so as to provide reasonable expectations for the patients and guidance for the clinical treatment. METHOD: Electronic databases PubMed, YZ365. COM, WANFANG DATA, CMJD, CHKD, CNKI were searched using relevant keywords. Extracted data included author, year of publication, diagnosis, et al. Reported treatment outcomes were clustered into speech discrimination and hearing abilities. Meta-analyses were performed on studies with numerical results using random or fixed effects model. RESULT: There were eight randomized control studies including 442 patients. Comparing speech perception of prelingually deaf children after cochlear implantation younger than three years old (experimental group) and 3-6 years old (control group), three and six months after operation showed that experimental group performed significantly worse than control group; 12 months after operation showed that experimental group performed significantly better than control group. Comparing hearing abilities, three and six months after operation showed that experimental group performed significantly worse than control group; 12 months after operation showed showed that experimental group performed significantly better than control group. Comparing speech perception of younger or older than 4. 5 years old children showed that after 1.5-2 years of operation children implanted younger than 4.5 years of age performed significantly better than children implanted older than 4.5 years old. Comparing speech perception of 7-12 years old children showed that after 3, 6, 12 months of operation patients of 7-12 years old performed significantly better than those children older than 12 years old. Comparing speech perception of implantation younger or older than 18 years old (7-14 yeas old was group A, > 14-18 yeas old was group B, older than 18 yeas old was group C) showed that after one and four years of operation A > B > C, and there were significant differences among them. Comparing warble tone threshold average (WTA) showed that after one year of operation A < B < C, and there were significant differences among them. However, after four years of operation, there was no significant difference among them. CONCLUSION: Prelinguistically deafened patients younger than three years old with cochlear implantation, insisting on scienctific rehabilitation training for a long period of time can receive the optimal recovery effect. The older patients are suggested as early as possible receiving cochlear implantation. The longer they are implanted, the better results they will receive. Moreover, the younger age they are implanted, the faster postoperative language progress they will receive. Further controlled studies with longer follow-up periods and more person included may make the effectiveness of cochlear implantaion more reliable.

Clinical observation on hearing conditions of centenarians in northern district of China.

CONCLUSION: The hearing conditions of the centenarians were quite poor as regards hearing thresholds and speech detection ability. OBJECTIVE: To investigate hearing conditions of centenarians. METHODS: A total of 54 centenarians in Rizhao and Linyi Districts in Shandong Province were investigated to assess hearing conditions of centenerians comprehensively by questionnaire investigation, pure-tone audiometry, acoustic immitance, intelligence evaluation, and speech detection scores. Also, 135 individuals were recruited as controls and divided into four groups according to their age: 45-59 years, 60-69 years, 70-79 years, and 80-89 years. RESULTS: The hearing thresholds of the centenarians were dramatically higher than those of the control group (p < 0.05) and all centenarians suffered moderate to profound hearing loss according to the World Health Organization (WHO) criteria. Few centenarians had normal level of speech detection scores. All centenarians showed descending hearing curve, and the hearing threshold of the male centenarians at 8000 Hz was higher than that of the females (p = 0.047). There was a significant air-bone conduction gap in the centenarians (p < 0.05).

Cartilage engineering using chondrocyte cell sheets and its application in reconstruction of microtia.

The imperfections of scaffold materials have hindered the clinical application of cartilage tissue engineering. The recently developed cell-sheet technique is adopted to engineer tissues without scaffold materials, thus is considered being potentially able to overcome the problems concerning the scaffold imperfections. This study constructed monolayer and bilayer chondrocyte cell sheets and harvested the sheets with cell scraper instead of temperature-responsive culture dishes. The properties of the cultured chondrocyte cell sheets and the feasibility of cartilage engineering using the chondrocyte cell sheets was further investigated via in vitro and in vivo study. Primary extracellular matrix (ECM) formation and type II collagen expression was detected in the cell sheets during in vitro culture. After implanted into nude mice for 8 weeks, mature cartilage discs were harvested. The morphology of newly formed cartilage was similar in the constructs originated from monolayer and bilayer chondrocyte cell sheet. The chondrocytes were located within evenly distributed ovoid lacunae. Robust ECM formation and intense expression of type II collagen was observed surrounding the evenly distributed chondrocytes in the neocartilages. Biochemical analysis showed that the DNA contents of the neocartilages were higher than native human costal cartilage; while the contents of the main component of ECM, glycosaminoglycan and hydroxyproline, were similar to native human costal cartilage. In conclusion, the chondrocyte cell sheet constructed using the simple and low-cost technique is basically the same with the cell sheet cultured and harvested in temperature-responsive culture dishes, and can be used for cartilage tissue engineering.

Mutations in the mitochondrial 12S rRNA gene in elderly Chinese people.

CONCLUSION: Our data indicate that the mitochondrial 12S rRNA gene, and particularly the A827G mutation, may be associated with susceptibility to age-related hearing loss. OBJECTIVE: Hearing loss associated with aging is common among elderly persons. In all genetic backgrounds, mitochondrial DNA (mtDNA) mutations may be one of the most important factors contributing to aging and age-related hearing loss. The mitochondrial 12S rRNA is a hot spot for deafness-associated mutations in Chinese populations. The purpose of the present study was to elucidate the relationship of 12S rRNA gene polymorphisms and age-related hearing loss. METHODS: The 12S rRNA gene polymorphisms were detected by direct sequencing. Statistical analyses were performed to assess the associations between age-related hearing loss and 12S rRNA gene variants. RESULTS: We report here a systematic mutational screening of the mitochondrial 12S rRNA gene in 662 elderly subjects from the general population with various hearing threshold levels (211 controls and 451 age-related hearing loss subjects). Mutational screening of the mitochondrial 12S rRNA gene identified 55 nucleotide changes, including 4 mutations localized at highly conserved sites and 51 known variants. Of the known deafness-associated mutations in the mitochondrial 12S rRNA gene, the incidence of the A1555G mutation was 0.15%, A827G was 4.38%, T1095C was 0.45%, and T1005C was 3.78%. The incidence of the other known variants was 0.15-99.85%. We found statistically significant differences in the proportions of subjects with the A827G mutation among the various age-related hearing loss groups and normal controls.

Effect of Binghuang ear drop treatment on otitis externa in guinea pigs.

To investigate the pharmacodynamic effects of Binghuang ear drop on acute suppurative otitis externa in guinea pig model. Thirty guinea pigs were randomly divided into three groups, with ten animals in each group. Group A animals had normal ear canal and Binghuang ear drops (two drops, B.I.D) were applied in both ears for 7 days; Group B animals had induced otitis externa and received identical prescription as group A; Group C had normal ear canal and were treated with normal saline (two drops, B.I.D) for 7 days. After the treatments, the external morphology of ear canals was observed and the paraffin sections of external auditory canal were prepared and examined under the microscope. The inflammatory manifestation and cell infiltration into the skin of group B was significantly attenuated after the Binghuang ear drops treatment. In contrast, no allergy or side effects were produced by Binghuang ear drops application in the animals with normal ear canals. Binghuang ear drops could be used to treat acute otitis externa by eliciting anti-bacterial effects.

Hydrogen-saturated saline protects intensive narrow band noise-induced hearing loss in guinea pigs through an antioxidant effect.

The purpose of the current study was to evaluate hydrogen-saturated saline protecting intensive narrow band noise-induced hearing loss. Guinea pigs were divided into three groups: hydrogen-saturated saline; normal saline; and control. For saline administration, the guinea pigs were given daily abdominal injections (1 ml/100 g) 3 days before and 1 h before narrow band noise exposure (2.5-3.5 kHz 130 dB SPL, 1 h). The guinea pigs in the control group received no treatment. The hearing function was assessed by the auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) recording. The changes of free radicals in the cochlea before noise exposure, and immediately and 7 days after noise exposure were also examined. By Scanning electron microscopy and succinate dehydrogenase staining, we found that pre-treatment with hydrogen-saturated saline significantly reduced noise-induced hair cell damage and hearing loss. We also found that the malondialdehyde, lipid peroxidation, and hydroxyl levels were significantly lower in the hydrogen-saturated saline group after noise trauma, indicating that hydrogen-saturated saline can decrease the amount of harmful free radicals caused by noise trauma. Our findings suggest that hydrogen-saturated saline is effective in preventing intensive narrow band noise-induced hearing loss through the antioxidant effect.

Analysis of the heteroplasmy level and transmitted features in hearing-loss pedigrees with mitochondrial 12S rRNA A1555G mutation.

BACKGROUND: Mitochondrial cytopathies are characterized by a large variability of clinical phenotypes and severity. The amount of mutant mitochondrial DNA (mtDNA) in a cell, called the heteroplasmy level, is an important determinant of the degree of mitochondrial dysfunction and therefore disease severity. Understanding the distribution of heteroplasmy levels across a group of offspring is an important step in understanding the inheritance of diseases. Recently, the mtDNA A1555G mutation was found to be associated with non-syndromic and drug-induced hearing loss. RESULTS: Here, we report five pedigrees with multiple members having the A1555G mutation and showing diverse clinical manifestations and different heteroplasmy levels. Clinical evaluations revealed that the hearing impairment phenotypes varied with respect to the severity of hearing loss, age of onset of hearing loss, and pattern of audiometric configuration. These five Chinese pedigrees had different penetrance of hearing loss, ranging from 10-52%. A molecular study showed that the average heteroplasmy rates of the five pedigrees were 31.98% (0-91.35%), 78.28% (32.8-96.08%), 87.99% (82.32-94.65%), 93.34% (91.02-95.05%), and 93.57% (91.38-94.24%). There was no gradual tendency of heteroplasmy to increase or decrease along with transmission. A study of the relationship between clinical features and genetic background found that the percentage of deafness was 0 when the heteroplasmy level was less than 50%, 25% when the heteroplasmy level was 50-80%, 47.06% when the heteroplasmy level was 80-90%, and 57.58% when the heteroplasmy level exceeded 90%. The risk of deafness rose with the heteroplasmy level. CONCLUSIONS: The results suggest that there are large random shifts in the heteroplasmy level between mothers and offspring with the A1555G mutation; heteroplasmy could disappear randomly when the heteroplasmy level of the pedigree was low enough, and no regular pattern was found. The heteroplasmy level may be one of the factors influencing the penetrance of deafness caused by the mtDNA A1555G mutation.

[Meta-analysis of the efficacy of cochlear implantation in deaf patients with inner ear malformation].

OBJECTIVE: Assess and compare the clinical efficacy and safety of cochlear implantation in deaf patients with inner ear malformation and in the ones with normal inner ear structure, so that to clarify whether it is effective to restore hearing for the deaf patients with inner ear malformation. METHOD: The literature with relevant key words were retrieved in the databases including PubMed, YZ365. com, WANFANG data, CMJD, CHKD and CNKI with language limited to Chinese and English. Extracted data included author, year of publication, diagnosis, treatment, et al. The clinical efficacy of cochlear implantation was assessed by the complications, electrode impedance, behavior T-level, hearing abilities and speech discrimination. Meta-analysis was performed using random or fixed effects model according to the heterogeneity of data. RESULT: There were 11 randomized control studies involving 655 patients included in this study. There was no statistically significant difference among the deaf patients in mixed inner ear-malformation group, Mondini group and large vestibular aqueduct syndrome group in the aspects of postoperative complications, electrode impedance, behavior T-level, hearing abilities and speech discrimination. CONCLUSION: Cochlear implantation could be the way of treatment and rehabilitation for deaf patients with inner ear malformation. Further controlled studies with longer follow-up periods and more multiracial cases included may help to evaluate the efficacy of cochlear implantation for deaf patients with inner ear malformation more reliably.

Clinical investigation on the beneficial effects of the Chinese medicinal herb Gushen Pian on sensorineural deafness and tinnitus.

The objective is to study the therapeutic effects of Gushen Pian on sensorineural deafness according to the Phase II clinical trial protocol, as approved for novel traditional Chinese medicines by Ministry of Health of PRC. This is a double blind study in which 120 patients were allocated randomly into treatment and control groups and an open treatment group (40 cases in each group). Patients in the treatment groups were administrated with Gushen Pian and controls received placebo. Routine examination of blood and urine, hepatic and renal function tests and pure tone audiometry were performed before and after treatment. Clinical symptoms and therapeutic outcomes were compared and evaluated. For double-blind treatment group, the total effective rate of deafness was 42.2% and total relieved rate of deafness was 4.6%; for double-blind control group, the total effective rate of deafness was 18.7% and total relieved rate of deafness was 0%; for simple treatment group, the total effective rate of deafness was 58.7% and total relieved rate of deafness was 6.3%. For double-blind treatment group, the total effective rate of tinnitus was 89.2% and total relieved rate of tinnitus was 59.5%; for double-blind control group, the total effective rate of tinnitus was 30.8% and total relieved rate of tinnitus was 5.1%; for simple treatment group, the total effective rate of tinnitus was 74.3% and total relieved rate of tinnitus was 57.1%. The double-blind treatment showed statistically significant differences from control group. The medication could effectively alleviate aural fullness, dizziness, lassitude of loins and knees, dysphoria with feverish sensation in chest, insomnia, and fatigue, etc. No adverse effect was reported during treatment; no abnormal results were reported in blood, urine, faces, heart function, liver function and kidney function examination. Gushen Pian had beneficial effect on deafness and tinnitus and could effectively alleviate aural fullness, insomnia, etc., without any adverse effects.

Mitochondria toxin-induced acute cochlear cell death indicates cellular activity-correlated energy consumption.

The different cell types within the cochlea may have a specific contribution to the pathological changes during metabolism failure, which may provide clues for developing novel strategies for inner ear therapy. In order to evaluate activity-correlated cell death during metabolism failure in the cochlea, 3-nitropropionic acid was used to irreversibly inhibit the respiratory chain. Dose-response of the cochlear cells to 3-nitropropionic acid was analyzed in vitro. 3-Nitropropionic acid was administered onto the round window of guinea pigs. Cell death was identified by terminal transferase labeling the free 3'OH breaks in the DNA strands in vivo and propidium iodide nuclear permeation in vitro. As a result, 23.6 and 96.3 % cell death were induced by 10 and 100 mM 3-nitropropionic acid, respectively, in vitro. In the guinea pigs, 500 mM 3-nitropropionic acid induced vestibular dysfunction and severe to profound hearing losses. The cells that are the most sensitive to 3-nitropropionic acid treatment include the stria marginal and intermediate cells, epithelial cells of the Reissner's membrane, and spiral ligament fibrocytes (types II and V). Moderate sensitive cells were satellite fibrocytes of the spiral limbic central zone, osteocytes of the cochlear shell, hair cells, and spiral ganglion cells. Reduction of neurofilament in the soma and periphery processes of spiral ganglion cells occurred after the exposure. These results may be relevant to the mechanisms of injury in sudden onset sensorineural hearing loss and hazardous substance exposure-induced hearing loss.

The differentiation of mesenchymal stem cells into inner ear hair cell-like cells in vitro.

CONCLUSION: Bone marrow mesenchymal stem cells (MSCs) have the ability to differentiate into hair cells, and this method of culturing MSCs provides a useful tool for studies on mammalian cochlear hair cell regeneration. OBJECTIVE: To investigate a method to induce bone marrow MSCs to differentiate into inner ear hair cells. METHODS: Rat bone marrow MSCs were isolated from healthy rats and cultured in vitro. To make sure that the cultured cells were bone marrow MSCs, the expression of MSC markers such as SH2, CD31, CD34, and CD44 genes on the cultured cells was assessed by RT-PCR. Adipogenic cells and osteogenic cells were induced by the differentiation of the cultured cells, respectively, suggesting that the cultured cells have the characteristic of pluripotent differentiation. Then they were induced to differentiate into neural stem cells and hair cell progenitor cells. Immunohistochemistry experiments were carried out to detect the expression of molecular markers. Scanning electron microscope samples were prepared for observation of the morphology of the cells. RESULTS: Rat bone marrow MSCs were successfully isolated, purified, cultured, and identified in vitro. They were also successfully induced to differentiate into neural progenitor cells and then hair cell-like cells that expressed myosin VIIa.

Functional mutation of SMAC/DIABLO, encoding a mitochondrial proapoptotic protein, causes human progressive hearing loss DFNA64.

SMAC/DIABLO is a mitochondrial proapoptotic protein that is released from mitochondria during apoptosis and counters the inhibitory activities of inhibitor of apoptosis proteins, IAPs. By linkage analysis and candidate screening, we identified a heterozygous SMAC/DIABLO mutation, c.377C>T (p.Ser126Leu, refers to p.Ser71Leu in the mature protein) in a six-generation Chinese kindred characterized by dominant progressive nonsyndromic hearing loss, designated as DFNA64. SMAC/DIABLO is highly expressed in human embryonic ears and is enriched in the developing mouse inner-ear hair cells, suggesting it has a role in the development and homeostasis of hair cells. We used a functional study to demonstrate that the SMAC/DIABLO(S71L) mutant, while retaining the proapoptotic function, triggers significant degradation of both wild-type and mutant SMAC/DIABLO and renders host mitochondria susceptible to calcium-induced loss of the membrane potential. Our work identifies DFNA64 as the human genetic disorder associated with SMAC/DIABLO malfunction and suggests that mutant SMAC/DIABLO(S71L) might cause mitochondrial dysfunction.

Expression and clinical significance of cathepsin B and stefin A in laryngeal cancer.

The aim of this study was to investigate the roles of the cathepsin B cysteine protease and its endogenous inhibitor stefin A in laryngeal cancer. Immunohistochemistry was employed to detect the expression of cathepsin B and stefin A in 84 patients with laryngeal cancer, respectively. The protein expression of stefin A was negatively associated with lymphatic metastasis, recurrence of laryngeal cancer and the survival rate, which was not observed with cathepsin B protein expression. Both down-regulation of cathepsin B and up-regulation of stefin A in vitro significantly inhibited the migration, invasion and proliferation of laryngeal cancer cells, respectively. Our results strongly suggest that stefin A may be a potential predictor of laryngeal cancer and may be used in the molecular diagnosis and gene therapy of laryngeal cancer. Cathepsin B may be used as a promising therapeutic target in the treatment of laryngeal cancer.