水杨酸钠降低庆大霉素所致耳蜗自由基含量的实验研究

目的 采用电子顺磁共振法观察水杨酸钠对庆大霉素注射过程中耳蜗组织羟自由基呈增加的预防作用。方法 耳廓反射良好的豚鼠随机分成３组,庆大霉素组、庆大霉素＋水杨酸钠组和正常对照组。取标本前和标本制备时向耳蜗组织加入自由基捕捉剂５,５－ｄｉｍｅｔｈｙｌ－ｐｙｒｒｏｌｉｎｅ－１－ｏｘｉｄｅ（ＤＭＰＯ）,用ＥＰＲ直接检测耳蜗组织中自由基含量。结果 正常对照组耳蜗组织可测出较弱的羟（ＯＨ）自由基信号,庆大霉素注     

庆大霉素对内侧橄榄耳蜗传出神经毒性作用的形态学观察

目的 观察庆大霉素慢性耳中毒前后蒙古沙鼠人侧橄榄耳蜗传出神经的形态改变及其与细胞损害的关系,以探讨ＭＯＣ传出神经在氨基糖甙类抗生素慢性耳中毒中的重要性。方法 采用改良的乙酰胆碱酯酶组化染色和甲苯胺蓝＝苏木素染色法,全耳蜗铺片观察健康对照组和庆大霉素组耳蜗ＭＯＣ传出神经和外毛细胞的分布特征,并测量耳蜗ＭＯＣ传了神经纤维、末梢及ＯＨＣ的数量。结果 停经后３周出现耳蜗ＭＯＣ纤维和末梢损害,损害程度随时间     

庆大霉素对内侧橄榄耳蜗传出神经毒性作用的形态学观察

目的观察庆大霉素慢性耳中毒前后蒙古沙鼠内侧橄榄耳蜗（ｍｅｄｉａｌｏｌｉｖｏｃｏｃｈｌｅａｒ,ＭＯＣ）传出神经的形态改变及其与毛细胞损害的关系,以探讨ＭＯＣ传出神经在氨基糖甙类抗生素慢性耳中毒中的重要性。方法采用改良的乙酰胆碱酯酶组化染色和甲苯胺蓝苏木素染色法,全耳蜗铺片观察健康对照组和庆大霉素组耳蜗ＭＯＣ传出神经和外毛细胞（ｏｕｔｅｒｈａｉｒｃｅｌ,ＯＨＣ）的分布特征,并测量耳蜗ＭＯＣ传出神经纤维、末梢及ＯＨＣ的数量。结果停药后３周出现耳蜗ＭＯＣ纤维和末梢损害,损害程度随观察时间延长而加重,１１周最明显,且损害部位主要在耳蜗底回,与毛细胞损害的特征一致。结论耳蜗ＭＯＣ传出神经可能在庆大霉素慢性耳中毒时ＯＨＣ的损害中起重要作用。     

聚天冬氨酸对庆大霉素抑制耳蜗肌醇脂质信使系统的影响

目的 观察聚天冬氨酸(polyaspartic acid,PAA)对庆大霉素(gentamicin,GM)抑制耳蜗肌醇脂质信使系统的影响,进一步探讨PAA对庆大霉素耳毒性拮抗作用机制。方法 采用[~3H]-肌醇参入法和高效液相色谱分析法(high performance liquid chromatography,HPLC)测定不同给药组、不同给药时间豚鼠耳蜗组织肌醇磷酸酯(inositolphosphates,IPs)、多磷酸肌醇磷脂(polyphosphatidylinositol,PPI)及磷脂酶 C(PPI phospholipase C,PLC)。结果 ①给药1天后不同给药组间耳蜗组织IPs、PPI及PLC均无显著性差异(P>0.05)。②给药5天后单用GM组耳蜗组织PPI增加、Ips和PLC减低,与PAA+GM组及其他二对照组间有显著性差异(P<0.01)。③给药10天后单用GM组耳蜗组织PPI、IPs及PLC与PAA+GM组及其他二对照组间有显著性差异(P<0.01),但与单用GM5天相比,PPI变化不明显,IPs和PLC升高。结论 PAA对GM抑制耳蜗肌醇磷酸酯信使系统有拮抗作用,从而起到对GM耳毒性连锁反应早期阶段的保护作用。     

聚DL—天冬氨酸对庆大霉素耳毒性拮抗作用的实验研究

目的 研究聚ＤＬ－天冬氨酸（ＰＡＡ）对Ｆ－３４４大鼠庆大霉素（ＧＭ）耳毒性的拮抗作用。方法 选用健康Ｆ－３４４大鼠５０只,随机分４组：Ｉ为ＧＭ、Ⅱ为ＰＡＡ＋ＧＭ、Ⅲ为ＰＡＡ、Ⅳ为生理盐水对照组;通过观测４组大鼠不同时期、不同频率听性脑干反应（ＡＢＲ）阈值的改变;计数耳蜗毛细胞死亡率,以观察ＰＡＡ对Ｆ－３４４大鼠ＧＭ耳蜗毒性的拮抗作用;用双向扩散血清培养基检测法观察ＰＡＡ对ＧＭ抗菌活性的影响。结果     

聚DL-天冬氨酸对庆大霉素耳毒性拮抗作用的实验研究

目的　研究聚ＤＬ天冬氨酸（ｐｏｌｙ ＤＬａｓｐａｒｔｉｃ ａｃｉｄ,ＰＡＡ） 对Ｆ３４４ 大鼠庆大霉素（ｇｅｎｔａｍｉｃｉｎ,ＧＭ） 耳毒性的拮抗作用。方法　选用健康Ｆ３４４ 大鼠５０ 只,随机分４ 组：Ⅰ为ＧＭ、Ⅱ为ＰＡＡ＋ ＧＭ、Ⅲ为ＰＡＡ、Ⅳ为生理盐水对照组;通过观测４ 组大鼠不同时期、不同频率听性脑干反应（ａｕｄｉｔｏｒｙ ｂｒａｉｎｓｔｅｍ ｒｅｓｐｏｎｓ,ＡＢＲ）阈值的改变;计数耳蜗毛细胞死亡率,以观察ＰＡＡ对Ｆ３４４ 大鼠ＧＭ 耳蜗毒性的拮抗作用;用双向扩散血清培养基检测法观察ＰＡＡ 对ＧＭ 抗菌活性的影响。结果　Ⅰ组短纯音１０ ｋＨｚ、８ ｋＨｚ ＡＢＲ阈值与其他３ 组差异有显著性（ Ｐ＜ ０．０１） ,给药１８ ｄ 耳蜗毛细胞死亡率与其他３ 组间差异也有显著性（ Ｐ＜０ ．０１）。结论　ＰＡＡ对庆大霉素的耳毒性具有拮抗作用,且不减低其抗菌活性。     

黄芩苷抑制庆大霉素致小鼠听神经细胞损伤的实验研究

目的探讨黄芩苷(baicalin, BA)对庆大霉素(gentamicin, GM)致小鼠耳蜗螺旋神经节(spiral ganglion, SG)细胞毒性的拮抗作用.方法用MTT法检测庆大霉素对SG细胞的毒性作用,用紫外分光光度法测定各实验组SG细胞总超氧化物歧化酶(T-SOD)活性,谷胱甘肽过氧化物酶(GSH-PX)活性和丙二醛(MDA)含量.结果黄芩苷能显著抑制GM所致的SG细胞中T-SOD和GSH-PX活性降低及MDA含量升高.结论黄芩苷通过清除耳蜗螺旋神经节细胞内氧自由基和抑制脂质过氧化反应,拮抗庆大霉素耳毒性作用.     

庆大霉素致豚鼠耳蜗毛细胞凋亡时Caspase-3的表达

目的探讨庆大霉素所致耳蜗外毛细胞的损伤特点及耳毒性机制。方法豚鼠随机分3个组,分别腹腔注射庆大霉素、庆大霉素加速尿、生理盐水各连续6天,比较用药前后各组豚鼠畸变产物耳声发射（distortion product otoacoustic emissions,DPOAE）变化、耳蜗铺片、毛细胞凋亡情况及Caspase-3在毛细胞的表达。结果注射庆大霉素和庆大霉素加速尿2个组,用药后DPOAE明显下降,耳蜗铺片见毛细胞损伤明显,细胞凋亡发生及Caspase-3免疫复合物阳性表达。结论庆大霉素可致豚鼠耳蜗毛细胞损伤并加速凋亡,Caspase-3在毛细胞凋亡过程中起重要作用。     

氨基糖甙类抗生素致聋家系线粒体DNA1555G点突变分析

目的考察１５５５Ｇ点突变与氨基糖甙类抗生素致聋的对应关系，建立相应的基因诊断方法提供依据。方法收集了３个有明确氨基糖甙类抗生素应用史的母系遗传耳聋家系１３人（包括聋人和听力正常者）的外周静脉血标本，聚合酶链反应扩增线粒体ＤＮＡ，Ａｌｗ２６Ｉ限制性内切酶分析、ＤＮＡ斑点杂交和ＤＮＡ序列分析检测１５５５Ｇ点突变。结果家系１和３的７份样品均为１５５５Ｇ点突变阳性，家系２的６份样品为１５５５Ｇ点突变阴性。结论发现１个１５５５Ｇ点突变阴性的氨基糖甙类抗生素致聋家系，说明线粒体ＤＮＡ１５５５Ｇ点突变不是氨基糖甙类抗生素遗传易感性唯一的分子基础。     

Experimental study on polyaspartic acid inhibition of gentamicin-induced generation of reactive oxygen species in guinea pig cochlea]

OBJECTIVE: To observe the polyaspartic acid(PAA) inhibition of gentamicin-induced reactive oxygen species generation in cochlea of guinea pig and to investigate the protective mechanism of polyaspartic acid on gentamicin ototoxicity. METHODS: Eighty-eight guinea pigs were divided randomly into four groups (GM, PAA + GM, PAA, and Saline). Gentamicin-induced reactive oxygen species (ROS) formation in cochlear tissue was detected directly with electron paramagnetic resonance (EPR) spectrometry at 1st, 5th and 10th day after administration of the drugs. At the same time, ABRs of guinea pigs were recorded and ultrastructural changes of lysosomes in the cochlear hair cells were observed with transmission electron microscopy. RESULTS: 1. At 1st day after administration of PAA and GM, there was some increase in EPR spectrometry in group GM and PAA + GM, There was no significant difference of ABR thresholds and ultrastructural changes of lysosomes in the cochlear hair cells among four groups(P > 0.05). 2. At 5th day, there was significant increase in of EPR spectrometry in group I (37.74 +/- 4.10, P < 0.01). At 10th day after administration of PAA and GM, there was no significant difference in EPR spectrometry among four groups (P > 0.05). In GM group, ultrastructural changes of lysosomes beneath cuticular plate of cochlear hair cells were more significant at 10th day than those at 5th day, including the increased number and volume of lysosome. In group GM, the longer the gentamicin administrated, the more significant increase in ABR thresholds had been noted. CONCLUSION: PAA significantly inhibits gentamicin-induced reactive oxygen species generation in cochlea of guinea pig, which showed that PAA has protective effect on gentamicin-ototoxicity and -phospholipidosis in guinea pigs.     

豚鼠耳蜗的转基因表达及其意义

目的:探讨耳蜗转基因表达的方法及意义。方法:经圆窗将复制缺陷重组腺病毒(含β-半乳糖苷酶基因,Ad.LacZ)注入豚鼠一侧耳蜗(接种耳)鼓阶,1周后观察接种耳及对侧耳蜗(非接种耳)转基因表达及听力情况。结果:接种耳蜗及对侧耳蜗均有Ad.LacZ表达,其分布相似,但对侧耳蜗中Ad.LacZ基因表达相对较弱,双侧耳接种Ad.LacZ前后听力无明显改变。结论:对侧耳蜗的转基因表达可能对某些内耳疾病的转基因治疗具有重要意义。     

γ-Aminobutyric acid receptor activation of outer hair cells in the guinea pig cochlea

Summary Gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter of the central nervous system, may also be released from olivocochlear efferent nerves reaching the outer hair cells of the cochlea. In the present study the cell potential of isolated outer hair cells of the third and fourth turns of the guinea pig cochlea was measured with patch-clamp electrodes. GABA-receptor agonists and antagonists were applied extracellularly. The cell membrane hyperpolarized in a reversible manner with increasing concentrations of extracellular GABA. Half-maximal hyperpolarization (2 mV) was achieved with approximately 10^7– M GABA. Desensitization was not observed. The hyperpolarizing effect of GABA was potentiated by the benzodiazepine clorazepate and was blocked by picrotoxin.     

A functional and histological study of the combined effects of gentamicin and aminooxyacetic acid on the organ of Corti of the guinea pig

Summary Aminooxyacetic acid (AOAA) is a transaminase inhibitor that has been shown to protect the inner ear from loud noises. This study was done to determine if it can also protect against the cochleotoxic action of gentamicin. Four groups of guinea pigs were injected with gentamicin in doses approximating a clinical therapeutic dose and then in ototoxic doses. Thereafter animals were treated with parenteral AOAA. The effect on hearing was investigated using Preyer's reflex measurements. All animals were sacrificed and their cochleas were examined histologically using the surface preparation technique and mid-modiolar semithin sections. Histocochleograms were plotted to compare the effects of treatment in the animal groups. There was no difference seen among the groups tested. Cochlear damage was nearly equal in all animals, and AOAA was not found to protect the cochlea against gentamicininduced ototoxicity of gentamicin. The mechanism of the ototoxicity produced is discussed on the basis of the findings. Additionally, hair cell degeneration was studied after therapeutic doses of gentamicin. Changes seen were found to be equal to or less than 5% of the hair cells and were scattered throughout the entire cochlea.This work was performed in the ENT Department, University of Tübingen, in a cooperative research project between Egypt and the Federal Republic of Germany (Channel System)Supported by a grant from the Deutsche Forschungsgemeinschaft (PL 79/3)