Adenoviral-mediated Hath1-EGFP gene transfer into guinea pig cochlea through intact round window membrane

Objective To study expression of adenoviral-mediated Hath1-EGFP gene in the guinea pig cochlea after transfer through intact round window membrane(RWM), and to assess its effects on hearing. Methods Twenty adult guinea pigs were used, of which: 12 were surgically inoculated with Ad-Hath1-EGFP in the bony groove of round window niche, and 8 with artificial perilymph. Auditory brainstem response(ABR) thresholds were determined in all animals before and 5 days after surgery. On post-surgery day 5 and day 14, animals were sacrificed and whole mounts of cochlea and frozen sections were examined. Results ABR tests showed no significant change of hearing after the surgery. Strong fluorescence staining in the cochleae was seen in Ad-Hath1-EGFP groups. The highest levels of gene expression were seen in the post-surgery day 5 group with little decrease on post-surgery day 14.The contralateral cochlea and those in the control groups were free of fluorescence staining. Conclusion The transgenic Hath1-EGFP can be effectively delivered into the inner ear through intact RWM, in an atraumatic manner.

Saturated hydrogen saline protects against noise-induced hearing loss

Objective To study effects of saturated hydrogen saline in preventing noise-induced hearing loss. Methods Fifteen guinea pigs were randomly divided into 3 groups (5 each), group one was for control, group two was treated with normal saline and group three was treated with saturated hydrogen saline, which was given intraperitoneally at 1 hour before noise exposure at 1 ml/100 g. One hundred rounds of impulse noise (157 dB SPL peak) were delivered as noise exposure. Immediately after exposure to impulse noise and on Days 1, 2, 4 and 8 following exposure, auditory brainstem response(ABR) thresholds were measured. Outer hair cell morphological changes and succinate dehydrogenase(SDH) activity were examined on Day 8 post-exposure. Results Immediately after noise exposure, ABR thresholds in saturated hydrogen saline treated animals were lower than the non-treated animals (P < 0.05). Microscopy showed little SDH staining, cell swelling and irregular cell arrangement in the non-treated or normal saline treated animals. Whereas in the saturated hydrogen saline treated animals, there was deep SDH staining with significantly reduced cell loss and more regular cellular arrangement compared to the other two groups. The surviving cells counts was 45.17 ±12.15 for non-treated animals, 44.50 ±10.02 for normal saline treated animals and,116.50±2.38 for animals treated with saturated hydrogen saline. While the count was similar between non-treated and normal saline treated animals, it was significantly higher in saturated hydrogen saline treated animals(P < 0.05). Conclusions Intraperitoneal injection of saturated hydrogen saline appears to protect the cochlea against noise-induced damage.

Measurement of Ca^(2+) Flow in Cochlear Cells Using Non-Invasive Micro-Test Technique

Objective To test Calcium ion(Ca2+) flow at the head and end of outer hair cells(OHCs) in resting state and in response to Nimodipine treatment.Methods Non-invasive micro-test techniques were used to study Ca2+ in isolated OHCs in adult guinea pigs.Results Four types of Ca2+ transport were identified in OHCs on basilar membrane tissue fragments:influx at the head of with efflux at the bottom(type 1):efflux at the head of OHCs with influx at the bottom(type 2);influx at the both head and bottom(type 3);and efflux at the both head and bottom(type 4).However,only type 1 and type 3 of Ca2+ ion transport were detected in the cochlea.We propose that Ca2+ ion transport exists in adult guinea pig cochlear OHCs in resting state and is variable.Ca2 + flow in OHC can be inhibited by Nimodipine in resting state.

Death mode-dependent reduction in succinate dehydrogenase activity in hair cells of aging rat cochleae

背景我们的以前的研究证明了 apoptosis 和坏死涉及毛细胞(HC ) 在老化 cochleae 的致病。更好理解为 HC 死亡的规定负责的生物机制，我们检验了 succinate 脱氢酶(同步数字系列)的活动， mitochondrial bioenergetic 酶在听觉的 brainstem 反应阀值在 4 点由音调爆炸得到了的老化 cochleae.Methods 的 HC ， 10 和 20 kHz 在幼仔( 2-3 月)和老化( 22-23 月)被测量 Wistar 老鼠。同步数字系列活动用 nitroblue tetrazolium monosodium 盐与比色的试金被评估。Corti 的标记同步数字系列的机关是双的与 propidium 染色了碘化物，设置的 DNA 荧光灯为 HC 原子核的说明的探查。所有标本与荧光显微镜学被检验，共焦的 microscopy.Results 老化老鼠与是的阀值移动展出了 ABR 阀值的重要举起在 20 kHz，在 10 kHz 的 28 dB，和在 4 kHz 的 25 dB 的 34 dB。与在耳蜗的功能的减小一致，老化 cochleae 展出了染色紧张在的同步数字系列的减小顶端并且 cochleae 的基础结束很多 apoptotic，坏死、失踪的 HC 是明显的。在染色的同步数字系列的减小以一种 cell-death-mode 依赖者方式出现了。明确地，标记的同步数字系列留在 apoptotic HC。相反，染色的同步数字系列显著地在变老的蜗在坏死的 HCs.Conclusions 被减少或不在，同步数字系列活动在经历 apoptosis 的 HC 被保存，但是实质地在坏死被减少。这些结果建议那 mitochondrial 精力充沛的功能在老化 cochleae 的致病涉及房间死亡小径的规定。