川芎嗪对卡那霉素耳中毒抗氧化作用的研究

通过检测豚鼠耳蜗组织超氧化物歧化酶（SOD）活力、丙二醛（MDA）含量、听神经复合动作电位（CAP）及扫描电镜观察，评价川芎嗪对卡那霉素（KM）耳中毒的抗氧化作用。结果显示：KM能 明显增加SOD活力、MDA含量及CAP阈值。同时应用KM和川芎嗪后，与KM组对比，听力有改善，SOD活力、MDA含量显著下降；与正常组相比，SOD、MDA无明显变化，听力轻度下降。推测脂质过氧化反应参与了KM耳中毒的过程。并探讨了川芎嗪对KM耳中毒抗氧化作用的可能机制。     

磷霉素在减轻卡那霉素耳中毒过程中的作用

本文采用磷霉素笔卡那霉素联合应用，经扫描电镜、透射电镜、耳蜗铺片和组织化学反应观察，了解磷霉素减轻卡那霉素耳毒性的机制以及卡那霉素所致耳毒性的发展过程。通过实验可以看到磷霉素有保护溶酶体膜的作用，所以能减轻卡那霉素的耳毒性，但由于它不能直接对抗AmAn耳毒性作用机制，因而不能完全预防其耳毒性。     

经大鼠面神经管引导耳蜗生物电反应

耳蜗生物电包括耳蜗内淋巴直流电位(EP),耳蜗微音器电位(CM),总和电位(SP),及听神经复合动作电位(CAP),这些不同的电位成份分别起源于耳蜗内不同的组织器官。除了EP是反映血管纹功能状态的静息电位之外,其它耳蜗生物电位都是声刺激诱发的耳蜗内不同组织细胞的电反应。因此,记录耳蜗生物电是直接反映耳蜗功能的最佳观察指标。许多传统的耳蜗生物电引导方法由于把电极置放到中耳腔内难免损伤中耳组织和结构而大都仅适用于急性或亚急性动物实验却不利于开展慢性实验的长期记录和观察。尤其在大鼠目前还缺少一种稳定可靠的长时期观察耳蜗生物电的引导方法。本实验将银丝电极经大鼠茎乳孔插入到面神经管水平段,由于面神经管水平段与耳蜗仅以很薄的骨壁相隔,因此可以从近距离引导出良好的耳蜗生物电反应。同时,由于电极埋藏在面神经管内而无需打开中耳腔,因此也避免了中耳粘膜或听骨链损伤以及因此而可能发生的术后中耳感染。我们在电极植入到同一动物测试耳面神经管水平段后不同时间测试的CAP和CM以及SP波形清晰并具有可靠的重复性,但是在不同动物之间的耳蜗生物电振幅却存在一定的差异,提示本方法引导的耳蜗生物电更适合于对同一测试耳进行实验前后的比较和观察。经面神经管这一天然骨性管道把引导耳蜗生物电的电极巧妙地植入到耳蜗隔壁,为更有效直接观察耳蜗各个组织器官对声刺激的反应提供了有益的参考经验。本文还就各种耳蜗生物电反应的特点及其相互内在联系以及与ABR之间的关系展开了讨论。     

葛根素减轻卡那霉素耳中毒的实验研究

目的观察葛根素在减轻豚鼠卡那霉素耳中毒中的作用.方法豚鼠30只随机分为两组对照组15只,肌注卡那霉素400mg/(kg     

卡那霉素耳中毒后豚鼠耳蜗细胞凋亡的研究

目的探讨卡那霉素耳中毒后耳蜗毛细胞有无凋亡.方法取听力正常豚鼠12只,实验组6只,对照组6只分别给予4000mg·kg-1·     

庆大霉素和卡那霉素耳中毒后雏鸡耳蜗毛细胞的再生

给２天龄纯种罗丝鸡分别肌注庆寺霉素（ＧＭ）和卡那霉素（ＫＭ）１０天，于停药当天、第１、２、３和４周处死小鸡，取出内耳基底乳头（ＢＰ）用扫描电镜和光镜观察，发现从ＢＰ的基底到中部有广泛性损害，毛细胞损失率约占４０％，在１周后受损部位表皮板上出现丛生的有微绒毛的再生毛细胞，随恢复期延长，再生毛细胞表面积增大，动纤毛和静纤毛束长出，３至４周受损部位已完全被发育成熟的再生毛细胞填补，ＢＰ形态恢复。     

卡那霉素耳中毒后鹌鹑耳蜗毛细胞损伤与再生的观察

４０天龄鹌鹑连续１０天肌注卡那霉素造成耳中毒后，分别于停药后１天或１、２、３、４和６周进行听神经动作电位测试及扫描电镜观察。发现停药后１天动物毛细胞大量破坏，听功能严重受损，同时还出现了新生毛细胞。随着时间推移，新生毛细胞逐渐增多，听功能也随之改善，直至停药后第６周耳蜗形态基本恢复正常时，高频听阈仍明显高于对照组。本实验结果表明，鹌鹑听毛细胞受损后几乎可完全再生，而且再生毛细胞具有感音功能，但功能改善明显迟于形态恢复。     

庆大霉素和卡那霉素耳中毒后雏鸡耳蜗毛细胞的再生

给２大龄纯种罗丝鸡分别肌注庆大霉素（ＧＭ）和卡那霉素（ＫＭ）１０天，于停药当天、第１、２、３和４周处死小鸡，取出内耳基底乳头（ＢＰ）用扫描电镜和光镜观察，发现从ＢＰ的基底到中部有广泛性损害，毛细胞损失率约占４０％，在１周后受损部位表皮板上出现丛生的有微绒毛的再生毛细胞，随恢复期延长，再生毛细胞表面积增大，动纤毛和静纤毛来长出，３至４周受损部位已完全被发育成熟的再生毛细胞填补，ＢＰ形态恢复。     

卡那霉素耳中毒后豚鼠耳蜗热休克蛋白的表达

目的　观察卡那霉素对热休克蛋白 70 (HSP70 )在豚鼠耳蜗中表达的影响。方法　取听力正常豚鼠随机分为实验组和对照组各 5只 ,分别给予 2 5 0mg·kg-1·d-1卡那霉素和生理盐水肌注 ,10天后处死。左耳铺片 ,右耳石蜡包埋切片。用免疫组织化学方法检测各组石蜡切片HSP70表达情况 ,通过计算机图像分析系统分析HSP70表达强度。结果　对照组中Corti器、血管纹、螺旋韧带、内螺旋缘、螺旋神经节HSP70表达呈弱阳性 ;耳蜗铺片显示内 ,外毛细胞正常。实验组中Corti器、血管纹、螺旋韧带、内螺旋缘HSP70表达呈强阳性 ,而在螺旋神经节呈弱阳性 ;耳蜗铺片显示外毛细胞大部分缺损。结论　卡那霉素能够诱导HSP70在豚鼠耳蜗中表达     

甲状腺素对豚鼠耳蜗毛细胞的保护作用

应用耳蜗外淋巴灌流技术、微电极技术及扫描、透射电镜技术，观察先服甲状腺素（10mg)三次后行外淋巴灌流卡那霉素（10^-3g/ml)1小时的豚鼠实验组（T／K）蜗内电位（EP），耳蜗微音电位（CM）和毛细胞的亚微结构变化，并与单纯灌流卡那霉素（10^-3g/ml)的豚鼠对照组（KM）进行比较，发现3组动物EP无明显差异；实验组（T／K）的CM下降较对照组（KM）少，两者有显著差异；实验组动物外毛细胞损伤较对照组动物轻，提示甲状腺素可能直接作用于听毛细胞，减轻卡那霉素对内耳的毒副作用。     

Cochlear Adaptation In Guinea Pigs

(1) In response to stimulus trains, the amplitude, latency and width of the N₁ component of the round-window-recorded action potentials (AP) reach an equilibrium value after about 5 stimuli. This final value is expressed in percent of the first response and depends on the stimulus intensity, stimulus duration and interstimulus interval (ISI). The equilibrium value is generally reached in an exponential way, the time constant of which also depends on the various stimulus parameters.

(2) The adaptation properties of the AP (i.e., those depending on the ISI) measured in this way are identical to those of action potentials recorded in single-nerve-fiber experiments. It is concluded that the AP reflects the properties of the nerve-fiber population by means of a weighted sum of the single-nerve-fiber contributions.

(3) It is possible to describe the N₁ component of the AP as sum of two partly overlappling Gaussian distribution functions. These two functions reflect the properties of two populations of nerve fibers which have a marked difference in their input-output and adaptation properties.

(4) Desynchronizing factor during adaptation, resulting in an N₁ broadening and a longer latency, arise from random fluctuations in both sunapse and nerve-cell membrane. These processes, however, must be identical for the two populations. For intensities ≥ 30 dB, population II dominates; and for intensities ≤ 70 dB, population I accounts for the major part of the compound response. In these two intensity regions, the parameter dependency of N₁ on stimulus intensity and ISI can be derived from single-nerve-fiber properties alone.

(5) In the intermediate intensity range, we observe anomalous behaviour of the N₁ parameters. It is suggested that a spatial desynchronization between the two populations, reflected in a latency difference, accounts for this behaviour.

(6) The two populations of nerve fibers might be identified with the radial and spiral afferent nerve fibers.     

Bioelectric Correlates of Kanamycin Intoxication

Young guinea pigs were given a series of subcutaneous injections of kanamycin (400 mg/kg body weight for 8-14 days) and after at least a two-week waiting period various electrical responses from the cochlea were measured. After the experiments the cochlea was perfused with osmic acid, surface preparations were used to obtain sensory (hair) cell counts, and cochleograms were prepared. In this report the relationship between the various electrical in dices of cochlear function (cochlear microphonic: CM. summating potential: SP, and whole nerve action potential: AP) and the degree and configuration of sensory cell damage is discussed. The electrode potentials were obtained with the differential electrode technique and localized CM and SP responses were collected from the first and often the third cochlear turns. Both the differential (DIF) and the average (AVE) SP components were studied. The results reveral that the CM production of inner hair cells alone is about 30-40 dB below that of the outer hair cells, and there is a 90° phase difference between the CM outputs of the two groups. The low intensity segment of the AP input-output function is missing in these cases, while they achieve near normal magnitude at high intensities. The inner hair cells apparently do not produce a positive DIF SP component     

豚鼠自发性耳声发射和自发性耳蜗微音电位的观察

对8只豚鼠的自发性耳声发射(SOAE)和自发性微音电位(SCM)进行观察,其中3只豚鼠的SOAE有二次及三次谐波.用外部纯音作为f_2,SOAE作为f_1,6只豚鼠产生了畸变产物耳声发射(2f_1-f_2).对侧宽带噪声刺激可抑制SOAE,肌注士的宁后可增强SOAE.SOAE的抑制性调谐曲线与双音抑制现象相似.结果提示,SOAE与SCM是外毛细胞的自发性电能动性振荡的产物,其自发性电能动性振荡模式及其听力学特性与外界声刺激引起的听觉特性一样,也受到传出神经系统的调控.     

Investigation of Topical Ciprofloxacin Ototoxicity in Guinea Pigs

Antibiotic eardrops mostly contain potentially ototoxic aminoglycosides. Ciprofloxacin is an alternative, and there is limited experience in its topical use. To investigate the topical ototoxicity of ciprofloxacin, 11 guinea pigs have been operated on. Transbullae silicone drug delivery tubes were placed to both ears of the animals. After the operation the guinea pigs were divided into two groups. The first group of animals received 0.2 ml of 4% gentamicin in one ear and 0.2 ml of 0.9% sodium chloride solution in the other. The second group received 0.2 ml of 0.2% ciprofloxacin in the test ear and 0.2 ml of 0.9% sodium chloride solution in the control ear. All drugs were given once a day on 7 consecutive days. Auditory brainstem response thresholds were recorded using click, 4 and 8 kHz logon stimuli before and after the operation, and after topical drug application. Results were statistically compared using Wilcoxon matched pairs signed-ranks test. Comparison of the thresholds before and after the operation, physiological saline application, as well as ciprofloxacin application yielded no statistically significant differences, whereas application of gentamicin resulted in total hearing loss. The results indicate that topical use of 0.2% ciprofloxacin is not ototoxic in guinea pigs.     

Effects of Neuropeptide Y on Cochlear Blood Flow in Guinea Pigs

The aim of this study was to clarify the effects of neuropeptide Y (NPY) on cochlear blood flow (CBF) in pigmented guinea pigs. NPY was administered with or without noradrenaline (NA) by systemic perfusion or perilymphatic local perfusion, and CBF was measured using a laser Doppler flowmeter. The systemic and perilymphatic administrations of NPY with NA induced greater prolongation of the increase in and recovery of CBF than the administration of NA or NPY alone. Continuous reduction in CBF induced by NPY may play an important role in the pathogenesis of stress-induced sensorineural hearing losses, such as sudden deafness.     

急性缺氧对豚鼠40Hz听觉相关电位的影响

目的：探讨急性缺氧条件下豚鼠40Hz听觉相关电位的改变。方法：利用气管持管辅助呼吸并给予不同浓度低氧气体建立动物模型,观察在不同程度的急性缺氧条件下,豚鼠40Hz听觉相关电位的改变,结果轻度缺氧条件下40Hz听觉相关电位各项参数无明显改变,加重缺氧则其阈值升高,各波平均振幅降低,P1波潜伏期延长,结论：40Hz听觉相关电位在轻度缺氧条件下比较稳定,这可能与40Hz听觉相关电位本身的特性有关,严重缺氧则表现为抑制。