Morphology of the octopus cell area of the cochlear nucleus in young and aging C57BL/6J and CBA/J mice

The influence of aging and age-related cochlear impairment on the ventral cochlear nucleus was evaluated by measuring morphological properties of the octopus cell area (OCA) in five age groups of inbred C57BL/6J and CBA/J mice (young adult to very old). The former strain demonstrates progressive cochlear sensorineural pathology and hearing loss during middle age; the latter has only modest sensorineural pathology late in life. Histological sections of the OCA were evaluated with serial sections and several strains for neurons, glia, and fibers, and Golgi impregnations were also used. Aging was associated with a decrease in volume of the OCA, a loss of neurons, slight decrease in neuron size, increased packing density of glial cells, and changes in dendrites ranging from minor to total loss of primary branches. The greatest changes occurred in extreme old age, beyond the median lifespan. Age-related changes were not exacerbated by sensorineural pathology in aging C57BL/6J mice. Individual octopus cells varied greatly in the extent of age-related abnormality.     

老年性聋病人红细胞变形能力的测定

①目的测定老年性聋病人和健康老年人的红细胞变形能力（ＲＣＤ），探讨老年性聋发生和发展的原因，为临床上有效地控制和延缓老年性聋提供理论依据。②方法应用ＢＬ－８８－Ｃ型激光衍射仪，测定肘静脉血的ＲＣＤ．③结果老年性聋组的ＲＣＤ（ＤＩ＝０．３６４±０．０２２）明显低于健康对照组（ＤＩ＝０．４０１±０．０２１），两组比较差异有极显著性（ｔ＝９．７６１，Ｐ＜０．００１）；重度高频听力下降组的ＲＣＤ（ＤＩ＝０．３５８±０．０２１）低于轻中度者（ＤＩ＝０．２７１±０．０２２），两组比较，差异有显著性（ｔ＝２．５２８，Ｐ＜０．０５）。④结论ＲＣＤ降低可能是导致和加重老年性聋发生和发展的原因之一。     

老年大鼠听力与耳蜗组织化学,免疫组织化学变化实验观察

自然老年大鼠（２８月龄）和成年鼠（３月龄），用７Ｓｌｌ－Ａ型电反应测试仪确定听阈并记录Ｉ波潜伏期和Ｉ－Ｖ波间期，耳蜗琥珀酸氢酶（ＳＤＨ）、ＰＡＳ、坚牢蓝组化染色和神经特异性和烯醇化酶（ＮＳＥ），Ｓ－１００的免疫组化当色（ＡＢＣ）法，分别观察耳蜗毛细胞、神经节细胞、听神经纤维及鞘膜变化。结果：老年大鼠听性脑干反应阈值升高，ＳＤＨ活性减弱，节细胞人可见多个脂褐素颗粒，神经纤维排列稀疏，节细胞内ＮＳＥ免     

Race and sex differences in age-related hearing loss: the Health, Aging and Body Composition Study

OBJECTIVES: To determine the prevalence of and risk factors for hearing loss in a sample of 2,052 older adults (aged 73-84; 46.9% male, 37.3% black) enrolled in the Health, Aging and Body Composition (Health ABC) Study. DESIGN: Cross-sectional analysis of a longitudinal cohort study. SETTING: Pittsburgh, Pennsylvania, and Memphis, Tennessee, areas. PARTICIPANTS: Random sample of Medicare beneficiary subjects enrolled in the Health ABC program from 1997 to 1998. They included 2,052 individuals: 660 white men (32.2%), 631 white women (30.8%), 310 black men (15.1%), and 451 black women (22.0%). Participants ranged in age from 73 to 84, with a mean age of 77.5. MEASUREMENTS: Hearing sensitivity was measured using pure-tone threshold testing. Hearing loss was defined based on two averages of hearing thresholds: 500, 1,000, and 2,000 Hz greater than 25-decibel (dB) hearing level (HL) (hearing loss); and 2,000, 4,000, and 8,000 Hz greater than 40-dB HL (high-frequency hearing loss). Potential hearing loss correlates, including demographics, medical history, ototoxic medication use, occupational noise exposure, and lifestyle factors, were collected via questionnaire. RESULTS: The prevalence of hearing loss was 59.9%; the prevalence of high-frequency hearing loss was 76.9%. Hearing loss was most common in white men, followed by white women, black men, and black women. Older age, white race, diabetes mellitus, cerebrovascular disease, smoking, poorer cognitive status, occupational noise exposure, and ear surgery were associated with hearing loss after multivariable adjustment. Race- and sex-specific risk factors included higher blood pressure and occupational noise exposure (white men), poorer cognitive status and smoking (black women), and low total hip bone mineral density (black men). Possible protective factors included salicylate use (overall sample, black men) and moderate alcohol intake (black women). CONCLUSION: Hearing loss was extremely common in this population. Because many of the identified hearing loss risk factors are modifiable, some of the burden associated with hearing loss in older people should be preventable.     

The mechanism of hearing loss in Paget's disease of bone

OBJECTIVES/HYPOTHESIS: The mechanism of hearing loss (HL) in Paget's disease of bone was investigated. The present study was a systematic, prospective, controlled set of clinical investigations to test the hypothesis that there is a general underlying mechanism of HL in Paget's disease of bone and to gain additional insights into the auditory and otologic dynamics of this disease. Specific questions were 1) whether the mechanism is cochlear or retrocochlear and 2) whether the bone mineral density of the cochlear capsule is related to hearing levels. STUDY DESIGN: Several double-blinded, cross-sectional, prospective, correlational studies were conducted in a population of elderly human subjects with skull involvement with Paget's disease versus a control population of elderly subjects free of Paget's disease. Demographic and clinical data were recorded. Longitudinal observations were made in subjects under treatment. METHODS: Subjects were recruited from a Paget's disease clinic. Pure-tone auditory thresholds, word recognition, and auditory brainstem responses (ABRs) were recorded. The dimensions of the internal auditory canals were measured using computed tomographic (CT) images and digital image analysis. The precision, accuracy, and temporal stability of methods to measure the bone mineral density of the cochlear capsule and an adjacent area of nonotic capsule bone were validated and applied. Correlations were sought between hearing levels and cochlear capsule bone mineral density. RESULTS: ABRs were recorded in 64 ears with radiographically confirmed Paget's disease involving the skull. Responses were absent in eight ears, all of which had elevated high pure-tone thresholds. ABRs were interpreted as normal in 56 ears; none were abnormal. The mid-length diameter and minimum diameter of the internal auditory canal of 68 temporal bones from subjects with Paget's disease were found to have no statistically significant relationship to hearing thresholds. The Pearson product-moment correlation coefficients (age- and sex-adjusted) in the group with Paget's disease involving the temporal bone were -0.63 for left ears and -0.73 for right ears for high-frequency air conduction pure-tone thresholds (mean of 1, 2, and 4 kHz) versus cochlear capsule density. Correlation coefficients (age- and sex-adjusted) between cochlear capsule density and air-bone gap (mean at 0.5 and 1 kHz) for the affected group were -0.67 for left ears and -0.63 for right ears. All correlations between hearing thresholds and cochlear capsule density in pagetic subjects were significant at P <.001. The regressions were consistent throughout the ranges of hearing level. There were no significant correlations between cochlear capsule mean density and hearing level in the volunteer subjects. CONCLUSIONS: The evidence supports the existence of a general, underlying, cochlear mechanism of pagetic HL that is closely related to loss of bone mineral density in the cochlear capsule. This mechanism accounts well for both the high-frequency sensorineural HL and the air-bone gap. Early identification, radiographic diagnosis of temporal bone involvement, and vigorous treatment with third-generation bisphosponates are important to limit the development and progression of pagetic HL.     

Effects of aging on peripheral and central auditory processing in rats

Hearing loss is a hallmark sign in the elderly population. Decline in auditory perception provokes deficits in the ability to localize sound sources and reduces speech perception, particularly in noise. In addition to a loss of peripheral hearing sensitivity, changes in more complex central structures have also been demonstrated. Related to these, this study examines the auditory directional maps in the deep layers of the superior colliculus of the rat. Hence, anesthetized Sprague–Dawley adult (10 months) and aged (22 months) rats underwent distortion product of otoacoustic emissions (DPOAEs) to assess cochlear function. Then, auditory brainstem responses (ABRs) were assessed, followed by extracellular single‐unit recordings to determine age‐related effects on central auditory functions. DPOAE amplitude levels were decreased in aged rats although they were still present between 3.0 and 24.0 kHz. ABR level thresholds in aged rats were significantly elevated at an early (cochlear nucleus – wave II) stage in the auditory brainstem. In the superior colliculus, thresholds were increased and the tuning widths of the directional receptive fields were significantly wider. Moreover, no systematic directional spatial arrangement was present among the neurons of the aged rats, implying that the topographical organization of the auditory directional map was abolished. These results suggest that the deterioration of the auditory directional spatial map can, to some extent, be attributable to age‐related dysfunction at more central, perceptual stages of auditory processing.     

Down-regulation of the large conductance Ca2+-activated K+ channel expression in C57BL/6J cochlea

Conclusion: The large conductance Ca²⁺-activated K^+?channels (BK) expression is decreased in the cochleae of age-related hearing loss (AHL) mice. BK channel may be associated with AHL.

Objective: AHL is the most common among elderly persons. BK channels act as sensors for membrane voltage and intracellular Ca^2+?and are essential for hearing. To investigate the distribution of BK channel in the cochleae of C57BL/6J mice, and the relationship between the expression of BK channel and the etiology of AHL.

Methods: BK expression was studied in the cochleae of C57BL/6J mice at various ages (4, 12, 26, 52 weeks). The expressions of BK at the protein and mRNA levels were detected by immunofluorescence technique, western blot and quantitative real time PCR.

Results: In comparison with 4-week-old mice, BK expressions in the cochleae at 12, 26 and 52 weeks of age were significantly and gradually decreased at both the protein and the mRNA levels. The immunofluorescence technique showed the BK channel was located in the hair cells and cells of the spiral ganglion, spiral ligament and stria vascularis and its expression also decreased with aging.     

多学科协作干预对老年性耳聋佩戴助听器者生活质量的影响

目的探讨多学科协作(MDT)干预对老年性耳聋佩戴助听器者生活质量的影响。方法将53例老年性耳聋患者随机分为干预组28例,对照组25例,干预组成立由耳鼻喉科医师、配验师、康复师、专科护士、社区护士、心理咨询师等组成的MDT团队,对照组采用社区常规健康教育。1个月后比较2组的相关知识掌握率、助听器佩戴依从性,3个月后比较2组的生活质量。结果 1个月后干预组相关知识掌握率、助听器佩戴依从性均高于对照组(P0.05),3个月后生活质量方面的改善也显著优于对照组(P0.05)。结论 MDT模式下的路径干预能提高老年性耳聋患者相关知识掌握率、助听器佩戴依从性,改善生活质量。     

葛根对老年性聋大鼠的治疗作用

目的:研究葛根对老年性聋大鼠的治疗作用.方法:选取月龄22～24个月Wistar大鼠32 只,随机分为4 组,每组8 只.对4组大鼠皮下注射不同剂量的葛根提取液,共4周,观察各组大鼠ABR的改变,比较各组动物血液流变学指标.结果:注射葛根后老年性聋大鼠反应阈明显改善(P<0.05),血液流变学指标较对照组明显好转(P<0.05),且葛根注射剂量为2 g/(kg*d)效果最佳(P<0.01),不良反应较轻.结论:葛根能明显改善老年性聋大鼠听力.本研究为阐明老年性聋的发病机制及临床上治疗老年性聋提供了理论依据.     

中国老年聋的研究现状和对策

老年聋严重影响老年人的语言交流和生活质量.在中国,老年聋及其后果已引起足够重视.虽然老年聋的预防和治疗的研究取得了不少进展,但是由于缺乏该病流行病学的人口统计学的系统研究,有关老年聋的有效治疗、听力的恢复和临床管理方面仍存在许多问题.本文根据国内已发表的论文,分析了中国老年聋的研究现状和对策,提出了老年聋的防治研究应重视听觉中枢处理过程障碍(central auditory processing disorder,CAPD)流行病学,老年聋和认知障碍的相关性研究.助听器的使用是老年聋获得听力的重要途径.最后,作者讨论了国内老年聋研究滞后的原因和解决的方法.