豚鼠噪声暴露后畸变产物耳声发射与外毛细胞的改变

为观察豚鼠噪声暴露后畸变产物耳声发射（ＤＰＯＡＥ）与内耳毛细胞的改变，将１６只健康豚鼠分为３组，正常对照组３只，噪声后即刻组３只，７ｄ组１０只。暴露于１１５ｄＢ ＳＰＬ模拟潜艇机舱噪声中４ｈ，暴露后即刻及７ｄ检测ＤＯＰＡＥ听力图及Ｉ／Ｏ函数曲线，光镜及扫描电镜观察耳蜗毛细胞的改变。暴露即刻组ＤＰＯＡＥ振幅消失（Ｐ〈０．０１），７ｄ后又恢复至暴震前的基线水平（Ｐ〉０．０５）。光镜及扫描电镜显示耳蜗２     

畸变产物耳声发射影响因素研究进展

畸亦物耳声发射（DPOAE）是由外毛细胞主动运动产生并从一定程度上反映外毛细胞的功能。由于DPOAE测量容易，客观、无损伤，可作为评价耳蜗功能的有效手段。但DPOAE的测试结果受多种因素影响。本文对近年来报道的有关影响因素从参数，仪器以及各种病理因素等诸方面进行了综述，并对其可能的影响机制及临床意义进行了初步探讨。     

次声波对豚鼠畸变产物耳声发射幅度的影响

目的观察强次声波暴露后豚鼠畸变产物耳声发射(DPOAE)的变化情况.方法将15只豚鼠置于频率8Hz、强度为135dB SPL的次声声场中连续暴露90分钟.分别于强次声波暴露前及暴露后即刻(2h内)、2天和5天做畸变产物耳声发射测试.结果强次声波暴露后豚鼠DPOAE的幅度值在各个频率段与暴露前相比均有明显的降低(p＜0.01),随着时间的推移,各个频率的幅度虽有一定的恢复,但仍明显低于暴露前水平(p＜0.01).结论强次声波可导致豚鼠耳蜗外毛细胞功能明显减退.     

不同放射剂量及时间对Balb/c小鼠畸变产物耳声发射和听性脑干反应的影响

目的　探讨不同剂量放射线照射及时间对小鼠畸变产物耳声发射（distortion product otoacoustic emission,DPOAE）、听性脑干反应（auditory brainstem response,ABR）的影响。方法 选取70只健康的Balb/c小鼠随机分成4组,对照组和3个实验组,实验组分别给予一次性8、12、16 Gy放射线剂量的照射,每个实验组随机分成2个小组,分别在照射后第3、7天对小鼠行DPOAE及ABR检测。结果　实验组小鼠分别接受8、12、16 Gy照射剂量后第3天DPOAE幅值与对照组比较无明显改变（P >0.05）;照射后第7天不同照射剂量组小鼠8、10、12 kHz的DPOAE幅值均较正常对照组小鼠显著降低（P <0.05）;正常对照组与各照射组小鼠的DPOAE幅值随着剂量的增加依次逐渐降低,在8、10、12 kHz有统计学意义（P <0.05）,在4、6 kHz无统计学意义（P >0.05）。分别给予小鼠8、12、16 Gy放射剂量后行ABR检测发现照射后第3天反应阈出现短暂的提高,照射后第7天反应阈恢复正常,呈波动性改变,照射第3天反应阈的改变与对照组比较有统计学意义;I、II潜伏期在照射后第3天较正常对照组时间显著延长（P <0.05）,在照射后第7天潜伏期恢复正常,与对照组比较没有明显改变（P >0.05）。 结论　放射线一次性照射后第7天可导致小鼠高频听功能出现损伤,但是耳蜗以上的听觉神经通路可能是短暂的可逆性功能障碍。     

畸变产物耳声发射影响因素研究进展

畸变产物耳声发射 (DPOAE)是由外毛细胞主动运动产生并从一定程度上反映外毛细胞的功能。由于DPOAE测量容易、客观、无损伤 ,可作为评价耳蜗功能的有效手段。但 DPOAE的测试结果受多种因素影响。本文对近年来报道的有关影响因素从参数、仪器以及各种病理因素等诸方面进行了综述 ,并对其可能的影响机制及临床意义进行了初步探讨     

Wistar大鼠畸变产物耳声发射长期稳定性观察

目的：观察Wistar大鼠畸变产物耳声发射（DPOAE）长期稳定性。方法：对12只（21耳）健康、无耳疾病Wistar大鼠，分别于产后2、4、8、16周时测试F2为553、783、1105、1560、2211、3125、4416、6250、837Hz各点DPOAE（2f1-f2,f2/f1=1.2,L1=L2=70dB SPL)幅值。结果：除2周龄Wistar大鼠在F2为553、783、1105Hz三点DPOAE幅值较其后各周低，且差异有显著性意义（P＜0．05）外，其他各周龄在各频率点DPOAE幅值差异均无显著性意义（P＞0．05）。结论：4－16周龄Wistar大鼠DPOAE幅值在各频率点相对稳定，DPOAE可作为4－16周龄Wistar大鼠听力跟踪实验的指标，以此判断相应时期内耳蜗功能的改变。     

不同缺铁期大鼠畸变产物耳声发射的改变

目的　观察不同饲养期铁缺乏大鼠畸变产物耳声发射 (DPOAE)的改变 ,探讨铁缺乏引起听毛细胞损伤的可能机制。方法　幼龄Wistar大鼠 ,随机分组 ,缺铁饮食饲养法复制铁缺乏动物模型 33只 ,标准饮食饲养 33只作对照。每组分别于喂养第 4、8、12周各随机取 11只测双耳DPOAE幅值。结果　铁缺组第 4周平均DPOAE幅值中、高频率段下移 ,在 2、4kHz两点下移具有显著性意义 (P <0 .0 5 )。第 8周比第 4周中高频率段下移明显 ,在 1.4、2、3、4、6、8kHz各点差异具有显著性意义 (P <0 .0 5 )。第 12周与第 8周对比 ,DPOAE幅值各点相近 (P >0 .0 5 )。结论　铁缺乏大鼠DPOAE幅值下降具有时间特征性     

早产儿畸变产物耳声发射特征研究

目的　研究早产儿畸变产物耳声发射 (distortionproductotoacousticemissions,DPOAE)幅值及检测通过率随孕龄 (postconceptionalage ,PCA)变化的趋势 ,探讨以耳蜗为主的外周听觉系统的发育过程。方法　PCA2 8～ 36周的早产儿 31人 (5 9耳 )和PCA37～ 4 1周的足月新生儿 19人 (35耳 )在出生后 3天～ 1周行DPOAE初测 ,对DPOAE初测未通过耳在 1周后进行复测 ,若复测未通过 ,于一周后再行复测 ,将全部测试结果按检测时PCA分成PCA <30周、PCA 30～周、PCA 32～周、PCA 34～周及PCA≥ 37周组 ,分析DPOAE幅值及通过率与检测时PCA的关系。结果　孕龄 <30周至 >37周 ,DPOAE通过率、各频率幅值呈现逐渐上升的趋势 ,且在孕龄 35周后趋于稳定。孕龄 <30周组通过率为 2 5 % ,≥ 37周组为 10 0 %。结论　外周听觉系统功能随PCA增加逐步完善 ,至PCA35周后发育趋于稳定 ,对PCA36周之前的早产儿行DPOAE检测时 ,其阳性结果 (未通过 )可能是生理性的 ,并非永久性听力障碍 ;早产儿的筛查时机宜选择理论上的PCA接近或达到足月的时间     

鼓膜穿孔对畸变产物耳声发射的影响

本文研究鼓膜穿孔对畸变产物耳声发射(DPOAEs)的影响。用豚鼠做成不同大小和不同部位的鼓膜穿孔模型 ,有些模拟伴有外淋巴瘘或听骨链中断 ,以研究对 DPOAEs的影响。用 Grason- StadlerGS16 0系统测定最常用的 2 f1- f2 DPOAE。先记录鼓膜完整时的基准水平。然后在鼓膜前后或后上切开 ,鼓膜穿孔的大小由 2 5 %扩大到 5 0 %、75 %和 10 0 % ,分别行耳声发射测定。因为 2 0 0 0 Hz以下的低频声刺激时 ,手术室的噪声对 DPOAE测定有明显影响 ,故测试频率均用 2 0 0 0 Hz以上。该作者在 12耳各种大小鼓膜穿孔、5耳外淋巴瘘和 4耳听骨链…     

Adaptation of Distortion Product Otoacoustic Emission in Humans

Previous studies of animals observed a phenomenon of adaptation of distortion product otoacoustic emission (DPOAE) and found that the phenomenon was mediated to a large extent by the medial olivocochlear (MOC) reflex. The present study investigated DPOAE adaptation in humans. The following stimuli were used: f2/f1 = 1.2; f2 = 2, 4, or 5.65 kHz; L2 = 50-65 dB SPL re 20 microPa rms, L1 - L2 = 0-15 dB, where L1 and L2 represent levels of the f1 and f2 tones, respectively; duration of two-tone burst = 5.5 s; interburst gap = 20 or 30 s; number of repetitions = 40 or 64. We analyzed the 2f1 - f2 DPOAE as a function of time using a method of heterodyne envelope detection. The subjects were 20 humans aged from 15 to 54 years (median = 21 years) with normal hearing. We observed that (1) humans exhibited DPOAE adaptation phenomenon; (2) the time course of DPOAE level was characterized by a 2-exponential function; (3) distributions of the fast and slow time constants were well separated with their median values being 69 ms and 1.51 s, respectively; (4) distributions of the magnitudes of the fast and slow adaptation components were largely overlapped with their median values being 0.65 and 0.40 dB, respectively; and (5) the combined magnitude of the adaptation ranged from 0.4 to 3.0 dB with a median of 1.10 dB. To our knowledge, the present study is the first published article to describe adaptation of DPOAE in humans. These results should help advance the basic knowledge of human cochlear mechanics operating under the control of the MOC feedback system and contribute to the development of practical applications such as identifying people at high risk of acoustical injury and a clinical test of the functional status of the MOC system.     

外毛细胞基底侧膜动力蛋白分布均一性的研究

目的 探讨OHC基底部是否存在动力蛋白(Prestin)的表达及其在侧膜三层结构中的定位.方法 分别取正常C57小鼠、Wistar大鼠及豚鼠耳蜗的单离外毛细胞,在激光共聚焦显微镜下,利用Prestin特异性抗体与细胞膜标记di-8-ANEPPS双染,对Prestin在单离OHC上的表达与分布情况进行观察.结果 ①OHC基底侧膜存在Prestin抗体的阳性染色,OHC底端亦见阳性染色;②与细胞膜标记di-8-ANEPPS染色相比,Prestin抗体的阳性染色位于细胞膜的外侧;③经低渗细胞外液处理后,OHC侧膜中的质膜层可与内层表皮下池(subsurfac cisternae,SSC)和中层质膜下小梁(cortical lattice,CL)分离,在激光共聚焦显微镜下,外毛细胞膜最外层的质膜层上可见明显的Prestin抗体阳性染色.结论 动力蛋白(Prestin)分布于外毛细胞膜中最外层的质膜层上,在细胞基底部细胞膜上亦有表达.     

畸变产物耳声发射临床应用价值的探讨

研究了７３例（１３９耳）纯音听阈正常耳及各种感音神经性聋耳的ＤＰＯＡＥ，发现ＤＰＯＡＥ对耳蜗功能异常的改变早于纯音测听，并可精确地反映耳蜗毛细胞在相关频率上的功能状态；ＤＰＯＡＥ幅值及引出率随纯音听阈的提高而下降，当纯音听阈＞５０ｄＢ（ＨＬ）时，ＤＰＯＡＥ幅值明显降低或缺失；蜗后病变耳ＤＰＯＡＥ正常，当蜗后病变累及耳蜗时，ＤＰＯＡＥ幅值可异常，其异常程度与纯音听阈不平行。认为ＤＰＯＡＥ有广泛临床应用价值。     

大鼠畸变产物耳声发射的基本特性

目的　探讨正常大鼠畸变产物耳声发射 (DPOAE)的基本特征。方法　采用CELESTA - 5 0 3型耳声发射分析仪对 4 0只 ( 80耳 )健康大鼠行DPOAE“听力图”和输入 输出曲线及阈值测试。结果　各频率的DPOAE检出率均为 10 0 % ;1kHz的DPOAE幅值为 17.6 0± 5 .96dBSPL ,反应阈值为 36 .6 7± 3.83dBSPL ;2kHz以上DPOAE幅值均大于 2 5dBSPL ,反应阈值低于 1kHz;I O曲线表明各频率DPOAE幅值随初始音的强度上升而增加 ,两者间存在极为显著的相关性 ;同频率、同强度时 ,DPOAE幅值、反应阈值两耳间差异均无显著性 (P >0 .0 5 )。结论　大鼠的DPOAE检出率高 ,幅值大 ,各项指标反应稳定 ,为实验动物的筛选及实验提供参考资料     

The Role of Cholinergic Transmission in Outer Hair Cell Functioning Evaluated by Distortion Product Otoacoustic Emissions in Myasthenic Patients

Outer hair cells (OHCs) are the source of otoacoustic emissions, following a tropomyosin-miosin-dependent contraction, which are regulated by the olivocochlear bundle via the release of acetylcholine (ACh). ACh acts on ACh receptors (AChR) located on the OHC post-synaptic membrane. In myasthenia gravis (M.G.) neuromuscular transmission is reduced due to the action of AChR autoantibodies. It has previously been shown that M.G. induces a reduction in transient evoked otoacoustic emissions (TEOAEs), which is reversed after administration of a cholinesterase (AChE) inhibitor. Distortion product otoacoustic emissions (DPOAEs) were recorded before and 60 min after oral administration of 60 mg pyridostigmine bromide in 25 patients with normal hearing affected by M.G. The results were compared with those from 25 age-matched normal controls. Mean values of DPOAE amplitude in myasthenic patients were significantly (p&lt;0.05) lower at all frequencies before drug administration. All patients showed an overall significant (p&lt;0.05) increase in DPOAE amplitude after drug administration, although without reaching the control values. Such a recovery was more evident and highly significant (p&lt;0.01) for middle and high frequencies and could be explained by a higher concentration of ACh receptors in the basal and middle cochlear turns. These data seem to confirm the role of ACh in the neurotransmission of the auditory efferent system and may represent a new in vivo model for the investigation of the physiology of this system.     

Functional Prestin Transduction of Immature Outer Hair Cells from Normal and Prestin-Null Mice

Prestin is a membrane protein in the outer hair cell (OHC) that has been shown to be essential for electromotility. OHCs from prestin-null mice do not express prestin, do not have a nonlinear capacitance (the electrical signature of electromotility), and are smaller in size than wild-type OHCs. We sought to determine whether prestin-null OHCs can be transduced to incorporate functional prestin protein in a normal fashion. A recombinant helper-dependent adenovirus expressing prestin and green fluorescent protein (HDAd-prestin-GFP) was created and tested in human embryonic kidney cells (HEK cells). Transduced HEK cells demonstrated membrane expression of prestin and nonlinear capacitance. HDAd-prestin-GFP was then applied to cochlear sensory epithelium explants harvested from wild-type and prestin-null mice at postnatal days 2-3, the age at which native prestin is just beginning to become functional in wild-type mice. At postnatal days 4-5, we investigated transduced OHCs for (1) their prestin expression pattern as revealed by immunofluorescence; (2) their cell surface area as measured by linear capacitance; and (3) their prestin function as indicated by nonlinear capacitance. HDAd-prestin-GFP efficiently transduced OHCs of both genotypes and prestin protein localized to the plasma membrane. Whole-cell voltage clamp studies revealed a nonlinear capacitance in transduced wild-type and prestin-null OHCs, but not in non-transduced cells of either genotype. Prestin transduction did not increase the linear capacitance (cell surface area) for either genotype. In peak nonlinear capacitance, voltage at peak nonlinear capacitance, charge density of the nonlinear capacitance, and shape of the voltage-capacitance curves, the transduced cells of the two genotypes resembled each other and previously reported data from adult wild-type mouse OHCs. Thus, prestin introduced into prestin-deficient OHCs segregates normally to the cell membrane and generates a normal nonlinear capacitance, indicative of normal prestin function.     

高频畸变产物耳声发射在新生儿听力筛查中的应用

目的 探讨高频畸变产物耳声发射(high frequency DPOAE,HFDPOAE)在新生儿听力筛查中的特点及应用价值.方法 对261例(522耳)新生儿(正常对照组93例186耳及疾病组168例336耳)同时进行常频畸变产物耳声发射(conventional frequency DPOAE,CFDPOAE)和HFDPOAE听力筛查测试,分别比较采用CFD-POAE和HFDPOAE的初筛阳性率以及不同组新生儿各频率DPOAE的平均幅值,并进行统计学分析.结果 对照组CFDPOAE的阳性率显著高于HFDPOAE(P=0.000),疾病组采用CFDPOAE和HFDPOAE的阳性率无显著性差异(P＞0.05);采用CFDPOAE时,对照组与疾病组的筛查阳性率无显著性差异(P＞0.05);采用HFD-POAE时,疾病组的筛查阳性率显著高于对照组(P=0.007).DPOAE的幅值在2、8、12和16 kHz频率时各组间有统计学差异;各组DPOAE平均幅值:对照组最高,早产儿和非听损伤危险因素相关疾病组仅次于对照组,其次为新生儿窒息组和黄疸组,具有二种及以上听损伤危险因素相关疾病组最小;各组新生儿频率-幅值函数曲线呈双峰型,在4 kHz为峰值低谷,在2和8～12 kHz分别为二个峰值.结论 HFDPOAE能较敏感地反映听觉的受损情况,并能降低CFDPOAE听力筛查的假阳性率,对高频听力障碍的早期发现可能具有一定的应用价值.     

Contralateral Suppression of Distortion Product Otoacoustic Emission in Children with Auditory Processing Disorders

Previous research has demonstrated that the amplitude of evoked emissions decreases in human sub-jects when the contralateral ear is stimulated by noise. The medial olivocochlear bundle (MOCB) is be-lieved to control this phenomenon. Recent research has examined this effect in individuals with auditory pro-cessing disorders (APD), specifically with difficulty understanding speech in noise. Results showed tran-sient evoked otoacoustic emissions (TEOAEs) were not affected by contralateral stimulation in these sub-jects. Much clinical research has measured the function of the MOCB through TEOAEs.This study will use an alternative technique, distortion product otoacoustic emissions (DPOAEs), to examine this phenomenon and evaluate the function of the MOCB. DPOAEs of individuals in a control group with normal hearing and no significant auditory processing difficulties were compared to the DPOAEs of children with signifi-cant auditory processing difficulties.Results showed that the suppression effect was observed in the control group at 2 kHz with 3 kHz of narrowband noise. For the auditory processing disorders group, no significant suppression was observed.Overall, DPOAEs showed suppression with contralateral noise, while the APD group levels increased overall.These results provide further evidence that the MOCB may have reduced function in children with APD.     

Distortion Product Otoacoustic Emission and Auditory Brainstem Responses in the Echidna (Tachyglossus aculeatus)

The auditory function of four wild-caught echidnas was measured using distortion product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs). Emission audiograms were constructed by finding the stimulus levels required to produce a criterion emission amplitude at a given stimulus frequency. For an emission amplitude of -10 dB SPL, the median "best threshold" was 28 dB SPL, and this minimum threshold occurred between 4 and 8 kHz for all animals. The relative effective range of auditory function was defined by the frequencies at which the audiogram was 30 dB above its best threshold. For the emission audiograms, the median lower-frequency limit was 2.3 kHz, the upper limit was 18.4 kHz, and the effective range was 2.7 octaves. The audiogram as measured by ABR was also found to be strongly "U" shaped with similar low- and high-frequency limits, i.e., from 1.6 to 13.9 kHz, with an effective range of 3.1 octaves. These results suggest that the echidna has a behavioral hearing sensitivity comparable to that of typical therian mammals (e.g., rabbits and gerbils) but with a significantly narrower frequency range. DPOAE responses were also measured in selected animals as a function of the variation of all four stimulus parameters (frequencies and intensities of both stimulus tones). Overall, the measured emission responses establish that the echidna does have a cochlear amplifier, and that it could be the same type as in therian mammals. The amplification mechanism in the echidna, currently unidentified, clearly operates to frequencies above 20 kHz, higher than the hearing function observed in any birds or reptiles but lower than for typical therian mammals. This raises the possibility that at least some aspects of the mammalian cochlear amplifier developed early in evolution, before the divergence of the monotremes (echidna and platypus) from the mainstream therian mammals (marsupials and placentals). In this respect, the presence or absence of outer hair cell electromotility in monotremes would have important consequences for understanding the function and evolution of the vertebrate inner ear.