Hearing loss (HL) is the most common sensory disorder, affecting all age groups, ethnicities, and gen-ders. According to World Health Organization (WHO) estimates in 2005, 278 million people worldwide have moderate to profound HL in both ears. Results of the 2002 National Health Interview Survey indicate that nearly 31 million of all non-institutionalized adults (aged 18 and over) in the United States have trouble hearing. Epidemiological studies have estimated that approximately 50%of profound HL can be attributed to genetic causes. With over 60 genes implicated in nonsyndromic hearing loss, it is also an extremely het-erogeneous trait. Recent progress in identifying genes responsible for hearing loss enables otolaryngologists and other clinicians to apply molecular diagnosis by genetic testing. The advent of the $1000 genome has the potential to revolutionize the identification of genes and their mutations underlying genetic disorders. This is especially true for extremely heterogeneous Mendelian conditions such as deafness, where the muta-tion, and indeed the gene, may be private. The recent technological advances in target-enrichment methods and next generation sequencing offer a unique opportunity to break through the barriers of limitations im-posed by gene arrays. These approaches now allow for the complete analysis of all known deafness-causing genes and will result in a new wave of discoveries of the remaining genes for Mendelian disorders. This re-view focuses on describing genotype-phenotype correlations of the most frequent genes including GJB2, which is responsible for more than half of cases, followed by other common genes and on discussing the im-pact of genomic advances for comprehensive genetic testing and gene discovery in hereditary hearing loss.
作者： 刊期： 2013年第01期
Growing evidence has been found to suggest that early development of the central auditory system is dependent on acoustic stimuli. Peripheral damage caused by noise exposure and ototoxic drugs can induce functional and anatomical changes along the auditory pathways. The inferior colliculus (IC) is a unique structure in the auditory system located between the primary auditory nuclei of the brainstem and the thala-mus. Damage to the IC inhibitory circuitry may affect central auditory processing and sound perception. Here, we review some of the striking electrophysiological changes in the IC that occur after noise exposure and ototoxic drug treatment. A common occurrence that emerges in the IC after peripheral damage is hyper-excitability of sound-evoked response. The hyperexcitability of the IC is likely related with reduced inhibi-tory response that requires normal peripheral inputs. Early age hearing loss can result in a long lasting in-creased susceptibility to audiogenic seizure which is related to hyperactivity in the IC evoked by loud sounds. Our studies suggest that hearing loss can cause increased IC neuron responsiveness which may be related to tinnitus, hyperacusis, and audiogenic seizure.
作者： 刊期： 2013年第01期
Noise-induced hearing loss is a common cause of acquired hearing loss in the adult population. Acoustic overstimulation causes cochlear damage through mechanical stress to the tissue. Consequently, complex molec-ular changes are initiated, and these changes lead to morphological and biological alterations in the cochlea, which in turn compromise the cochlear function and cause hearing loss. In the past 10 years, there have been significant advances in our understanding of the molecular mechanisms of noise-induced hearing loss. These advances are attributed, in part, to the development of high-throughput technologies for the global analyses of molecular changes. In this review, we briefly describe the newly developed methods for investigating the mo-lecular responses of the cochlea to acoustic trauma and the knowledge generated from these studies. We also discuss the strengths and limitations of each technique and the major challenges to investigate cochlear degen-eration following acoustic injury.
作者： 刊期： 2013年第01期
Hearing loss and tinnitus are among the most common consequences of long term noise exposure and re-main an under-addressed heath issue in most developing nations including China. The rapid industrializa-tion and life style changes in China increase the concern over noise exposure and noise induced hearing loss (NIHL). Research on NIHL in China is limited. The current paper reviews studies published in English and Chinese language literatures regarding noise exposure and NIHL in China. Their implication on the Chi-nese population is discussed. The possible utility of a research model such as the Dangerous Decibels? as a means to increase understanding of the scope of NIHL among the Chinese population, to educate the gener-al public in China (especially the young) about NIHL and its prevention, and to study effects of language and cultural factors on international information dissemination and behavioral interventions is proposed.
作者： 刊期： 2013年第01期
作者： 刊期： 2013年第01期
Mutations in mitochondrial tRNA genes have been shown to be associated with maternally inherited syn-dromic and non-syndromic deafness. Among those, mutations such as tRNALeu(UUR) 3243A>G associated with syndromic deafness are often present in heteroplasmy, and the non-syndromic deafness-associated tRNA mu-tations including tRNASer(UCN) 7445A>G are often in homoplasmy or in high levels of heteroplasmy. These tRNA mutations are the primary factors underlying the development of hearing loss. However, other tRNA mutations such as tRNAThr 15927G>A and tRNASer(UCN) 7444G>A are insufficient to produce a deafness phe-notype, but always act in synergy with the primary mitochondrial DNA mutations, and can modulate their phenotypic manifestation. These tRNA mutations may alter the structure and function of the corresponding mitochondrial tRNAs and cause failures in tRNAs metabolism. Thereby, the impairment of mitochondrial protein synthesis and subsequent defects in respiration caused by these tRNA mutations, results in mitochon-drial dysfunctions and eventually leads to the development of hearing loss. Here, we summarized the deaf-ness-associated mitochondrial tRNA mutations and discussed the pathophysiology of these mitochondrial tRNA mutations, and we hope these data will provide a foundation for the early diagnosis, management, and treatment of maternally inherited deafness.
作者： 刊期： 2013年第01期
Currently, most people with modern multichannel cochlear implant systems can understand speech in qui-et environment very well. However, studies in recent decades reported a lack of satisfaction in music percep-tion with cochlear implants. This article reviews the literature on music ability of cochlear implant users by presenting a systematic outline of the capabilities and limitations of cochlear implant recipients with regard to their music perception as well as production. The review also evaluates the similarities and differences be-tween electric hearing and acoustic hearing regarding music perception. We summarize the research results in terms of the individual components of music (e.g., rhythm, pitch, and timbre). Finally, we briefly intro-duce the vocal singing of prelingually-deafened children with cochlear implants as evaluated by acoustic measures.
作者： 刊期： 2013年第01期
Oxaliplatin, an anticancer drug commonly used to treat colorectal cancer and other tumors, has a number of serious side effects, most notably neuropathy and ototoxicity. To gain insights into its ototoxic profile, oxaliplatin was applied to rat cochlear organ cultures. Consistent with it neurotoxic propensity, oxaliplatin selectively damaged nerve fibers at a very low dose 1 μM. In contrast, the dose required to damage hair cells and spiral ganglion neurons was 50 fold higher (50 μM). Oxailiplatin-induced cochlear lesions initial-ly increased with dose, but unexpectedly decreased at very high doses. This non-linear dose response could be related to depressed oxaliplatin uptake via active transport mechanisms. Previous studies have demon-strated that axonal degeneration involves biologically active processes which can be greatly attenuated by nicotinamide adenine dinucleotide (NAD+). To determine if NAD+would protect spiral ganglion axons and the hair cells from oxaliplatin damage, cochlear cultures were treated with oxaliplatin alone at doses of 10 μM or 50 μM respectively as controls or combined with 20 mM NAD+. Treatment with 10 μM oxaliplatin for 48 hours resulted in minor damage to auditory nerve fibers, but spared cochlear hair cells. However, when cochlear cultures were treated with 10 μM oxaliplatin plus 20 mM NAD+, most auditory nerve fibers were intact. 50 μM oxaliplatin destroyed most of spiral ganglion neurons and cochlear hair cells with apop-totic characteristics of cell fragmentations. However, 50 μM oxaliplatin plus 20 mM NAD+treatment great-ly reduced neuronal degenerations and hair cell missing. The results suggested that NAD+provides signifi-cant protection against oxaliplatin-induced neurotoxicity and ototoxicity, which may be due to its actions of antioxidant, antiapoptosis, and energy supply.
作者： 刊期： 2013年第01期
Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.
作者： 刊期： 2013年第01期
The waltzing guinea pig may be a good model to investigate if genetic factor can change the sensitivity in noise-induced hearing loss. A total of 34 waltzig guinea pigs were studied and we found that there is no any significant increased sensitivity to noise trauma if the age-induced hearing loss was considered in waltz-ing guinea pig.
作者： 刊期： 2013年第01期
