Noise-induced hearing loss (NIHL) is defined by a strong noise exposure led up the hair cells to damage which caused sensorineural hearing loss.The occurrence of NIHL is mainly related to oxidative damage, such as reactive oxygen species.Oxidative damage is mainly related to the ROS produced by noise exposure which can cause cochlear ischemia, hypoxia, and mitochondrial damage, resulting in hair cell death, further led to hearing loss.Prevention or treatment measures of NIHL is to reduce the formation of ROS and the removal of ROS.Antioxidants have been used in clinical treatment.This article reviews the effects of reactive oxygen species in NIHL to further explore the pathogenesis and prevention or treatment measures of NIHL.

Simplified dose calculation model with high computation efficiency is often used to generate the dose matrices for beamlets in the inverse planning of the intensity modulate radiation therapy. It is likely that this simplification could degrade the quality of the final treatment plans. This paper is aimed at testing the influence of such simplification in dose calculations of beamlets and accordingly proposing methods to avoid severe degradation of the plans. Two simulation instances were adopted. The primary dose calculation model without involvment of scattering effect was used to generate the dose matrices of beamlets. The differential convolution superposition dose calculation model that well accounts for scattering effect was used to calculate the final dose distributions for given intensity profiles. It is found that the simplification in dose matrices of beamlets degrades the dose levels in the edge area of the targets, however, the degradation could be diminished or even avoided by adding a suitable margin around the targets or by using the multiple-shifted-beamlet-matrices (MSBM) method that was proposed in our previous paper.
Humans ; Radiometry ; methods ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; statistics & numerical data ; Radiotherapy, Conformal ; methods ; Scattering, Radiation

Objective To investigate the protective effect of dexamethasone on hearing loss induced by canalwall-down mastoidectomy.Methods A total of 76 patients (76 ears) were randomized to dexamethasone group and non dexamethasone group with 38 patients in each group.For dexamethasone group,gelfoam soaked with dexamethasone (5 mg/ml) was topically applied to the round window niche at the end of the surgery,and dexamethasone was administrated intravenously at the dosage of 5 mg/50 kg immediately after the surgery.While for non-dexamethasone group,dexamctbasone was not used.The pure-tone audiograms were performed before mastoidectomy and 90 days after the surgery.Absolute bearing change was defined as the difference in hearing thresholds in decibels before and after the surgery.Results The changes of bone conduction thresholds in dexamethasone group were 8.3± 3.9 dB at 6 kHz,11.3±5.2 dB at 8 kHz,and 10.1±7.2 dB for HPTA (4-6-8 kHz high tone average).As in non-dexamethasone group,the changes of bone conduction thresholds were 13.7±4.6 dB at 6 kHz,25.1±5.4 dB at 8 kHz,19.3±9.7 dB for HPTA.There were significant differences in the changes of bone conduction thresholds between dexamethasone and non dexamethasone groups at frequencies of 6 kHz (P=0.039),8 kHz (P=0.007) and HPTA (P=0.009).Conclusion The results demonstrated that application of dexamethasone significantly reduced sensorineural high frequencies (6 kHz and 8 kHz) hearing loss after canal-wall down mastoidectomy,thus the use of dexamethasone is recommended.

Objective To study the protective effects of salvia miltiorrhiza on acute acoustic trauma (AAT) showed by temporary threshold shifts (TTS) induced by impulse noise.Methods A total of 62 male soldiers from a boot camp were randomly divided into the experimental group and the control group,each with 31 persons.The experimental group was treated with salvia miltiorrhiza,and the control group with placebo.Salvia miltiorrhiza was taken orally at the dosage of 780 mg each time,three times a day for 3 consecutive days before the live fire training and 1 day after the live fire training.The pure tone thresholds of right ears of these two groups were measured and compared 72 hours before live fire training and 6 hours after the live fire training.Results The puretone averages at 0.5,1 and 2 kHz of the right ears of the experimental group and the control group before live fire training were 16.32±6.12 dB and 16.21±5.42 dB,respectively,and the averages at 4,6 and 8 kHz were 14.22±5.16 dB and 14.89±5.38 dB,respectively.There were no significant differences between the 2 groups(P＞0.05).The PTAs of the right ears of the experimental group and the control group 6 hours after live fire training were 21.88±5.71 dB and 21.66±6.62 dB,respectively(P＞0.05),while the HPTAs were 25.89 ± 7.97 dB and 39.75 ± 7.84 dB,respectively(P＜0.01).There were significant differences in TTS between the two groups at 4,6 and 8 kHz(P＜ 0.01).Conclusion Salvia miltiorrhiza can reduce TTS at high frequencies induced by AAT.It has a potential preventive effect on AAT.