Localization of sirtuins (SIRT1-7) in the aged mouse inner ear

Conclusion: The expression of sirtuin in vestibular end organs and cochlea responds differently to age-related changes. Down-regulation of SIRT1, 3, and 5 in the cochlea may weaken the protective activity regarding degeneration of the organ of Corti as well as of spiral ganglion cells, resulting in the development of age-related hearing loss. An increase in SIRT 1, 4, or 5 in vestibular tissue could indicate an increased need of detoxification of reactive oxygen species and an increased anti-ageing potential. Objective: To analyse the expression of sirtuins (SIRT1-7) in the normal young and old mouse inner ears. Methods: Young (8 weeks) and old (22 months) CBA/J mice were used in this study. Localization of SIRT1-7 in the inner ear, i.e. cochlea, vestibular end organs, and vestibular ganglion, was investigated using real-time PCR and immunohistochemistry. Results: In the vestibular end organs, the expression of SIRT1, 2, 4, 5 (both mRNA and protein), SIRT6, and 7 (only mRNA) was found to be increased, while a slightly decreased immunoreactivity was observed in SIRT3. In the cochlea, the expression of SIRT1, 3, and 5 (both mRNA and protein) was decreased in the old mice, whereas no noticeable difference was observed regarding SIRT2, 4, 6, or 7.     

Hearing loss and depressive symptoms in elderly patients

Aims: Hearing loss is a common disability that has a profound impact on communication and daily functioning in the elderly. The present study assesses the effects of hearing aids on mood, quality of life and caregiver burden when hearing loss, comorbidity and depressive symptoms coexist in the elderly. Methods: A total of 15 patients aged older than 70 years suffering from hearing loss and depressive mood were recruited. Comorbidity was evaluated by the Cumulative Illness Rating Scale, functional ability by the Activities of Daily Living scale and the Lawton Instrumental Activities of Daily Living scale, cognitive capacity by the Mini‐mental State Examination and the Clock Drawing Test, psychological status by the Center for Epidemiological Studies‐Depression scale, and quality of life by the Short Form (36) Health Survey. Caregiver burden was appraised by the Caregiver Burden Inventory. Testing was carried out at baseline and at 1‐, 3‐ and 6‐month intervals, assessing the use of binaural digital and programmable hearing aids. Results: Reduction in depressive symptoms and improved quality of life at statistically significant levels were observed early on with the use of hearing aids. In particular, general health (P < 0.02), vitality (P < 0.03), social functioning (P < 0.05), emotional stability (P < 0.05) and mental health (P < 0.03) all changed for the better, and were maintained for the study duration. The degree of caregiver burden also declined, remaining low throughout the study. Conclusions: The benefits of digital hearing aids in relation to depressive symptoms, general health and social interactivity, but also in the caregiver – patient relationship, were clearly shown in the study. The elderly without cognitive decline and no substantial functional deficits should be encouraged to use hearing aids to improve their quality of life. Geriatr Gerontol Int 2012; 12: 440–445.     

Changes in frequency representation in the auditory system of mice with age-related hearing impairment

Aging C57BL/6 mice show a progressive decline in sensitivity to sound, beginning with high frequencies. In the inferior colliculus (IC), tonotopic organization — the orderly representation of frequency from low to high along the dorsoventral dimension — shows marked changes. No neurons respond to high frequencies, most respond best to a restricted range of frequencies, and ventral neurons become responsive to low frequencies. These age-related response alterations have implications for hearing problems of aging humans.     

Subjective hearing-related quality-of-life is a major factor in the decision to continue using hearing aids among older persons

Conclusion: Audiological parameters alone do not determine the choice to use hearing aids (HA). Subjective hearing-related QoL is a major factor that determines whether or not an older person will continue to wear HA.

Objective: This study aimed to identify which audiological parameters and quality-of-life (QoL) measures determine whether or not older persons will continue wearing HA.

Methods: Charts of 157 patients aged ≥65 years who attended the HA service unit at the Otolaryngology Department were retrospectively reviewed. After HA fitting and a trial, the patients were divided into groups, depending upon whether or not they wanted to continue wearing the HA (users, 58.2%; non-users, 41.8%) and then audiological parameters were compared between them. At least 4 months after the HA fitting, the self-reported QoL questionnaire, Hearing Handicap Inventory for the Elderly (HHIE), was mailed to all 157 patients and HHIE scores were compared between HA users and non-users.

Result: Speech discrimination score and dynamic range did not significantly differ between HA users and non-users. A difference in the average hearing threshold was marginally significant. The response rate to the HHIE was 65.2%. Total HHIE and emotional scores were higher (more impaired) among HA users than non-users.     

老年性耳聋的研究进展

随着机体的衰老退化,代谢发生障碍,导致老年性耳聋,老年性耳聋的发生、发展与很多因素有关,目前缺乏有效的药物治疗手段。本文从基础研究及临床治疗康复方面做一综述。     

PNUTS 在 D-半乳糖诱导老化小鼠耳蜗中的表达

目的 观察 D-半乳糖诱导的老化小鼠耳蜗中蛋白磷酸酶 1 核目标亚基（PNUTS）的表达。 方法 6 周龄清洁级昆明小鼠 20 只随机分为对照组和 D-半乳糖组, 每组 10 只。 D-半乳糖组小鼠颈背部皮下注射 D-半乳糖 800 mg/（kg·d）; 对照组颈背部注射等量生理盐水, 均为每日 1 次, 连续 8 周。 造模完成后, 进行听脑干反应（ABR）测试检测小鼠听力变化; 取 2 组小鼠耳蜗, 采用 Western blot 检测 PNUTS 及 p53 蛋白表达; 免疫组织化学观察 PNUTS 蛋白在耳蜗毛细胞、螺旋神经节细胞及血管纹中的表达与分布情况。 结果 D-半乳糖组小鼠在 8、12、24 kHz 这 3 个频率下的 ABR 阈值与对照组差异均无统计学意义。 PNUTS 蛋白在小鼠耳蜗毛细胞、螺旋神经节细胞及血管纹细胞中有表达,且 D-半乳糖组小鼠耳蜗中 PNUTS 蛋白的阳性表达水平较对照组显著降低（P＜ 0.05）;而 p53 蛋白表达水平则显著升高（P＜ 0.01）。 结论 PNUTS 在小鼠耳蜗中有表达, 且 D-半乳糖能够诱导老化小鼠耳蜗中 PNUTS 表达下调。     

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.     

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.     

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.