奈替米星对豚鼠耳蜗毛细胞凋亡作用的影响

目的研究奈替米星对于豚鼠耳蜗毛细胞的凋亡作用。方法将豚鼠分为生理盐水对照组和奈替米星组,连续给药14 d,利用TUNEL法原位检测动物耳蜗毛细胞的凋亡情况。结果生理盐水对照组豚鼠耳蜗未见凋亡毛细胞,而奈替米星组豚鼠耳蜗基底回中第1、2排外毛细胞丢失,第3排外毛细胞呈阳性表达,第3回中第1排外毛细胞丢失,第2排外毛细胞呈阳性表达。第2回毛细胞中仅见第1排外毛细胞呈阳性表达。结论奈替米星作用于豚鼠耳蜗时可引起外毛细胞凋亡;奈替米星耳毒性的产生可能与其引起耳蜗毛细胞凋亡有关。     

2004新药与同类药物(4种)动物耳毒性实验观察

目的:观察氨基糖苷类新药2004与同类药物(4种)对动物的耳毒性.方法:120只白化豚鼠分别肌注同剂量的抗生素新药2004、庆大霉素、奈替米星、依替米星、威大霉素及生理盐水,21d后通过观察听性脑干反应阈值,通过眼震电图观察眼震抑制率(F),了解其听功能及前庭功能的变化;结合耳蜗铺片琥珀酸脱氢酶染色、火棉胶切片等方法观察耳蜗及前庭器官的形态学变化.结果:ABR阈移、耳蜗铺片毛细胞计数及内、外毛细胞的损害情况和病变范围、火棉胶切片观察结果同时表明这些药物的耳蜗毒性:庆大霉素>威大霉素>奈替米星>依替米星>新药2004.眼震抑制率(F)和前庭形态学结果表明这些药物的前庭毒性:威大霉素>庆大霉素>奈替米星>依替米星>新药2004.结论:氨基糖苷类新药2004在同类药物中的耳毒性是最小的.     

金纳多对奈替米星致耳毒性模型豚鼠的预防和治疗作用研究

目的:研究金纳多注射液对奈替米星导致豚鼠耳毒性的预防和治疗作用。方法:将48只豚鼠随机分成生理盐水对照组、奈替米星组、金纳多预防组和金纳多治疗组,以不同方式给药4wk后,比较各组豚鼠的耳廓反射阈、脑干诱发电位、Ⅲ波时间、血清铁离子浓度和SOD活性以及耳蜗毛细胞扫描电镜图。结果:4wk后金纳多预防组和金纳多治疗组的耳廓反射阈、脑干诱发电位、Ⅲ波时间分别为(33.75±4.20)dB、(25.63±3.71)dB、(3.91±0.18)ms和(27.27±4.54)dB、(32.95±4.30)dB、(4.30±0.16)ms,2组间比较存在显著性差异(P<0.01)。结论:金纳多注射液能预防和治疗奈替米星引起的豚鼠耳毒性,而且预防给药对耳毒性的改善作用大于治疗给药。     

鼓室内注射庆大霉素对耳蜗的毒性及刺五加的保护作用

目的探讨豚鼠局部应用用庆大霉素的耳蜗毒性作用,以及刺五加有无减轻庆大霉素耳蜗毒性的作用。方法选择健康豚鼠44只,随机分为三组:I为庆大霉素组,II为庆大霉素 刺五加组,III为生理盐水组;采用鼓膜穿刺法向豚鼠鼓室内注射药物,II组同时腹腔注射刺五加注射液;给药2周后检测三组动物的脑干诱发电位(ABR)的阈值变化,并取三组动物耳蜗底周标本行耳蜗铺片及切片,扫描及透射电镜检查。结果给药后I组ABR阈值与II组差异有显著性(P<0.01),耳蜗形态学观察示II组毛细胞受损程度较I组为轻。结论豚鼠鼓室内注射庆大霉素具有明显的耳蜗毒性,联合应用中药刺五加具有对抗庆大霉素耳毒性的作用。     

依替米星上市后安全性初步调查

注射用硫酸依替米星(Etimici,n爱大)是新一代氨基糖苷类抗生素,是我国自主研发并拥有自主知识产权的I类新药。爱大是在庆大霉素C1a的2-脱氧链霉胺1-N位上引入一个乙基而得到的衍生物,化学结构如图1所示。氨基糖苷类抗生素的主要不良反应是耳毒性和肾毒性。李兴启[1]等研究了3种氨基糖苷类抗生素对豚鼠耳蜗和前庭的影响,发现其影响大小依次为庆大霉素>阿米卡星>依替米星。王沛英[2]等比较了依替米星和奈替米星对豚鼠的耳毒性,结果二者对听性脑干诱发反应(ABR)阈值无显著影响,对前庭功能和耳蜗影响,奈替米星>依替米星。Kahlmeter[3]等报道…     

声损伤后豚鼠耳蜗热休克蛋白的表达

本文应用免疫组织化学技术,对110dBSPL 白噪声连续刺激3h 后豚鼠耳蜗内热休克蛋白72(HSP72)的表达进行了研究。结果发现声损伤后耳聋的豚鼠耳蜗三排外毛细胞HSP72呈阳性表达,正常对照豚鼠耳蜗未见阳性表达。认为热休克蛋白参与声损伤时耳蜗的应激反应,可能对毛细胞具有保护作用。     

赖氨酸阿司匹林对庆大霉素耳毒性的保护作用

目的探讨庆大霉素与赖氨酸阿司匹林混合用药对庆大霉素耳毒性的保护作用。方法健康♂豚鼠30只,随机分为3组:庆大霉素(GM)组、庆大霉素联合赖氨酸阿司匹林(GM LAP)组和对照组。GM组:12mg·kg-1,sc,qd;GM LAP组:GM 12 mg·kg-1 LAP 135 mg·kg-1,sc,qd。对照组:不给予任何药物。采用听性脑干反应(ABR)和耳蜗铺片观察用药前后听阈及耳蜗毛细胞形态学改变。结果GM组1、8 kHz ABR4 wk平均阈移与GM LAP组间差异有统计学意义(P<0．05)。耳蜗铺片结果显示,GM组底圈毛细胞有损伤,与正常组比较排列不整齐,毛细胞损伤向上逐渐减轻,与听阈升高的程度相平行;而GM LAP组的毛细胞排列整齐,无损伤。结论赖氨酸阿司匹林对庆大霉素耳毒性有保护作用。     

基因芯片技术研究威替米星及庆大霉素对HK-2细胞毒作用的机制

目的:研究威替米星和庆大霉素对体外培养的人肾小管上皮细胞系(HK-2)毒性作用的分子机制。方法:利用基因芯片技术检测3.2 mg.mL-1威替米星和庆大霉素作用于HK-2细胞48 h后基因表达的变化。结果:威替米星诱导HK-2细胞87个基因发生显著的上调,10个基因发生明显的下调。庆大霉素则引起62个基因表达显著上调,18个基因明显下调。差异表达的基因的功能涉及细胞生长增殖调控、凋亡、细胞周期、应激反应、转运及代谢酶等方面。结论:威替米星和庆大霉素改变细胞凋亡、应激反应及转运等相关基因表达可能参与其细胞毒性作用过程。     

庆大霉素对不同年龄组豚鼠的药动学与耳毒性研究

目的 :观察庆大霉素治疗剂量对幼年和成年豚鼠耳毒性的程度有无差异。方法 :幼年组、成年组豚鼠各 35只 ,对照组各 7只。按照与人类等效剂量肌肉注射庆大霉素 ,用高效液相法分析两组药动学特点 ;用光镜和电镜观察两组耳蜗损伤情况。结果 :单剂给药 2组均为二室开放模型 ,峰浓度和达峰时间差异无显著性 ;多次给药幼年组血药浓度明显高于同点成年组 ,存在明显体内药物蓄积 ;耳蜗损伤情况 ,幼年组较成年组重 ,且停药后毛细胞缺失数持续增加。结论 :等效人类治疗剂量的庆大霉素对幼年组豚鼠造成的耳毒性损害较成年组严重 ,且随用药时间延长而加重。幼年豚鼠的这种高敏性可能与药物从体内排出慢、易蓄积有关。     

5''-差向庆大霉素C1a及其衍生物的合成及生物活性的研究

以西索米星、奈替米星为母核 ,对双键进行选择催化氢化 ,得到氢化西索米星 ( 5′ 差向庆大霉素C1a)和新化合物氢化奈替米星 ( 5′ 差向依替米星 ) ,由于它们的空间构象发生改变导致抗菌活性的降低。     

Styrene induced alterations in biomarkers of exposure and effects in the cochlea: mechanisms of hearing loss.

It is known that styrene is ototoxic and causes cochlear damage starting from the middle turn. However, the cellular mechanism underlying styrene ototoxicity is still unclear. In this study, rats were exposed to styrene by gavage at different doses once a day for varying periods. Styrene levels in the cochlear tissues, styrene-induced permanent hearing loss, cochlear disruptions, and cell death pathways were determined. Styrene concentration in the cochlea varied along with the basilar membrane with the lowest level in the basal turn being consistent with the lowest styrene-induced threshold shift and hair cell loss in this region. After 3 weeks of exposure (5 days per week), a dose-dependent permanent hearing loss and a hair cell loss, especially in the midfrequency region, were observed. The styrene exposure at a dose of 200 mg/kg, which induced a blood level of 6.0 +/- 1.0 microg/g, caused an average of 4.4 +/- 0.5% OHC (outer hair cell) loss and 2-5 dB threshold shift in the cochlear region of 20-70% from the apex. A significant OHC loss was not observed until 7 days of exposure at a dose of 800 mg/kg. Deiters cells appeared to be the most vulnerable target of styrene. When condensed nuclei were observed in Deiters cells after a few days of styrene exposure (800 mg/kg), other cells were still intact. Apoptotic cell death appeared to be the main cell death pathway in the cochlea after styrene exposure. In the styrene-induced apoptotic OHCs, histochemical staining detected activated caspases-9 and 8, indicating that both mitochondrial-dependent pathway and death receptor-dependent pathway were involved in the styrene-induced cell death.     

Role of PGE-type receptor 4 in auditory function and noise-induced hearing loss in mice

This study explored the physiological roles of PGE-type receptor 4 (EP4) in auditory function. EP4-deficient mice exhibited slight hearing loss and a reduction of distortion-product otoacoustic emissions (DPOAEs) with loss of outer hair cells (OHCs) in cochleae. After exposure to intense noise, these mice showed significantly larger threshold shifts of auditory brain-stem responses (ABRs) and greater reductions of DPOAEs than wild-type mice. A significant increase of OHC loss was confirmed morphologically in the cochleae of EP4-deficient mice. Pharmacological inhibition of EP4 had a similar effect to genetic deletion, causing loss of both hearing and OHCs in C57BL/6 mice, indicating a critical role for EP4 signaling in the maintenance of auditory function. Pharmacological activation of EP4 significantly protected OHCs against noise trauma, and attenuated noise-induced hearing loss in C57BL/6 mice. These findings suggest that EP4 signaling is necessary for the maintenance of cochlear physiological function and for cochlear protection against noise-induced damage, in particular OHCs. EP4 might therefore be an effective target for cochlear disease therapeutics.     

卡那霉素对乙酰胆碱引起外毛细胞内钙离子浓度变化的影响

目的观察卡那霉素对乙酰胆碱升高外毛细胞内Ca2+浓度的影响,探讨卡那霉素耳毒性与耳蜗传出神经系统的关系。方法健康豚鼠15只断头处死,人工外淋巴液中分离活性良好的单离外毛细胞(OHC),分为空白对照组、乙酰胆碱(ACh)组和卡那霉素+ACh组。Fluo-3/AM负载30min,观察OHC内Ca2+荧光强度变化,即Ca2+浓度的变化。结果空白对照组OHC内Ca2+荧光强度基本不变。ACh组OHC内Ca2+荧光强度峰值平均升幅底部为3.06倍,顶部为1.61倍(n=6)。卡那霉素+ACh组OHC内Ca2+荧光强度峰值平均升幅底部为1.75倍,顶部为1.29倍(n=6)。结论卡那霉素能够明显抑制ACh引起的外毛细胞内Ca2+浓度升高的幅度。     

Perinatal cisplatin exposure induces cochlear apoptosis in newborn guinea pigs

The objective of this study was to evaluate the role of apoptosis in the development of the newborn cochlear structures and hearing loss caused by prenatal cis-diaminedichloroplatinum (cisplatin) exposure. Pregnant albino guinea pigs were intraperitoneally injected with 1.5 mg/kg body weight cisplatin once a day for seven consecutive days at gestational day (GD) 51 to GD 57. At postnatal day (PND) 14, pups were examined in the distortion product otoacoustic emission (DPOAE) task. The temporal bones were then removed and immunohistochemically stained for caspase 3, using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method. Cisplatin used during pregnancy could induce hearing loss in newborn and cochlear hair cell apoptosis. In conclusion, apoptosis may play an important role in the development of hearing impairment, caused by perinatal cisplatin exposure.     

Baicalin attenuates gentamicin‐induced cochlear hair cell ototoxicity

Gentamicin can lead to cochlear hair cells associated ototoxicity by inducing apoptosis and oxidative stress, which can be alleviated by baicalin, one flavonoid extracted from the root of Scutellaria baicalensis. The role of baicalin in protecting gentamicin‐induced hearing loss is unclear. Interference with oxidative stress was investigated in this study using House Ear Institute‐Organ of Corti1 (HEI‐OC1) cells, which were simultaneously treated with baicalin (0‐400 μm ) and gentamicin (0.2 or 1 mm ). MTT was used to assay cell viability and apoptosis was detected with Annexin V‐fluorescein isothiocyanate staining. The production of reactive oxygen species was indicated by 2,7‐dichlorofluorescein diacetate fluorescence intensity and mitochondrial depolarization was assayed by JC1‐mitochondrial membrane potential assay. Poly(ADP‐ribose) polymerase (PARP), cleaved‐caspase 3 and cleaved‐PARP expression were analyzed with western blot. Baicalin improved the viability of HEI‐OC1 cells and significantly reduced the oxidative stress and mitochondrial depolarization compared with the gentamicin treatment group. Gentamicin treatment increased the activation of PARP and caspase‐3, while such an increase could be downregulated by baicalin. Baicalin attenuates gentamicin‐induced cochlear hair cells ototoxicity, and such inhibition may be mediated by the regulation of reactive oxygen species production, mitochondrial depolarization, and caspase‐3 and PARP activation.     

Wnt通路对胰岛素样生长因子-1抑制小鼠毛细胞凋亡的作用

目的探讨胰岛素样生长因子-1(IGF-1)抑制小鼠毛细胞凋亡作用的调控机制。方法体外培养新生小鼠耳蜗基底膜。在分别含有正常对照培养液(A组)、0.5 mmol/L庆大霉素(GM)(B组)、0.5 mmol/L GM+1 ng/mL IGF(C组)、0.5 mmol/L GM+1 ng/mL IGF+5μg/mL wif(D组)、0.5 mmol/L GM+1 ng/mL IGF+10μg/mLwif(E组)、0.5 mmol/L GM+1 ng/mL IGF+15μg/mL wif(F组)的成分中培养24 h后收集细胞及固定。应用TUNEL法观察各组耳蜗毛细胞的凋亡情况。应用Western blot及Real-time PCR法观察Caspase-3的表达情况。结果 B组耳蜗毛细胞经刺激后,细胞凋亡数量及Caspase-3 mRNA和蛋白表达较A组明显上升(P<0.01),C组耳蜗毛细胞经IGF刺激后,细胞凋亡数量及Caspase-3mRNA和蛋白表达较B组明显下降(P<0.01),应用Wnt阻断剂(wif)后D、E及F组细胞凋亡数量及Caspase-3 mRNA和蛋白表达较C组升高,其中F组升高显著(P<0.01)。结论 IGF可能通过激活Wnt通路抑制毛细胞凋亡。     

Mercury (Hg2+) suppression of potassium currents of outer hair cells

The heavy metal mercury (Hg(2+)) is an insidious environmental pollutant that causes toxic effects on sensory systems. It is well known that the group IIB divalent cation Hg(2+) is an inhibitor of the group I monovalent potassium (K(+)) cation pore-forming channel in several biological preparations. Here, we used the whole cell patch clamp technique on freshly isolated outer hair cells (OHCs) of the guinea pig cochlea to record outward K(+) currents and inward K(+) currents treated with mercuric chloride (HgCl(2)). HgCl(2) affected K(+) currents in a voltage- and dose-dependent manner. The effects of HgCl(2) at 1.0-100 microM are more pronounced on onset peak current than on steady-state end current. HgCl(2) depolarized also the resting membrane potential. Although the effect of HgCl(2) at 1.0 microM was partially washed out over several minutes, the effects at 10 and 100 microM were irreversible to washout. Since K(+) channels of OHCs are targets for HgCl(2) ototoxicity, this may lead to auditory transduction problems, including a loss in hearing sensitivity. A better understanding of fundamental mechanisms underlying K(+) channelopathies in OHCs due to HgCl(2) poisoning may lead to better preventive or therapeutic agents.     

CO2激光对豚鼠耳蜗结构影响的实验研究

目的 研究低峰功率超脉冲CO2激光对豚鼠耳蜗结构的影响.方法 将24只豚鼠随机分为激光2W组、激光4 W组及对照组,每组8只,前两组分别以超脉冲CO2激光功率2 W、4 W行左耳蜗底周造孔,对照组只手术暴露耳蜗底周.术后21 d处死动物,应用耳蜗基底膜铺片、扫描电镜技术观察豚鼠耳蜗形态学的改变.结果 实验组与对照组的豚...