Ultrastructural changes in the spiral organ of cochlea at various intervals after exposure to impulse noise were investigated. Guinea pigs were exposed to 10 impulses noise of 166 dB SPL peak level which had duration of 0.1 ms. Thirteen of the exposed animals were used to systematically measure threshold shift at regular intervals from 30 min to 30d post-exposure. The other fourteen animals who had been exposed to the same impulse noise were killed for transmission electron microscopy (TEM) examination at the same intervals, respectively. The recovery pattern of threshold shift showed a nonmonotonic type. There was a progressive deterioration of changes in the hair cells between 30 min and 8h after exposure. Intracellular degeneration reached a peak at 8h and marked edema and swelling leading to deformation of the outer hair cells (OHCs), fused stereocilia, large vesicles in cytoplasm and swollen submembraneous cisterns were found. After that time the extent of degeneration in the hair cells reduced. The time sequence of changes in the spiral organ of cochlea in the present study was associated with the recovery pattern of threshold shift.

Humans ; Occupational Health ; Occupational Health Services ; standards ; Population Surveillance ; Program Evaluation

ObjectiveTo explore the possible mechanisms of Shujin Jiannao Formula （舒筋健脑方） for cerebral palsy. MethodsThirty 7-day-old SD rats were randomly divided into normal group， model group， and Shujin Jiannao Formula group， with 10 rats in each group. The model group and Shujin Jiannao Formula group established a cerebral palsy model by the classic Rice-Vannucci method. After successful modeling， rats in Shujin Jiannao Formula group were given Shujin Jiannao Formula 16 g/（kg·d） by gavage， while the normal group and model group were given normal saline 10 ml/（kg·d） by gavage once a day. After one week of intervention， the rats' body weight was measured， and Zea-Longa scores， the righting reflex test， and the hindlimb suspension test were conducted for assessment； hematoxylin-eosin （HE） staining and Nissl staining were used to observe pathological changes in brain tissue， and the number of Nissl-positive neurons was counted； enzyme-linked immunosorbent assay （ELISA） was employed to measure levels of inflammatory cytokines in the brain tissue， specifically interleukin-1β （IL-1β） and tumor necrosis factor-α （TNF-α）； immunofluorescence was used to detect the expression levels of neurofilament protein 200 （NF200） and myelin basic protein （MBP） in brain tissue； Western Blot analysis was conducted to determine the protein levels of phosphoinositide 3-kinase （PI3K）， protein kinase B （Akt/PKB/Rac）， and mammalian target of rapamycin （mTOR） in brain tissue. ResultsCompared with the normal group， rats in the model group showed significantly higher Zea-Longa scores and lower scores in the hindlimb suspension test （P＜0.01）； pathological findings revealed loose structure in the cerebral cortex， hippocampal atrophy， and neuronal damage in brain tissue. Levels of IL-1β and TNF-α elevated， and the number of Nissl-stained positive neurons in the cortex and hippocampal CA1 region reduced， and immunofluorescence intensity of NF200 and MBP， as well as protein expression levels of PI3K and mTOR， significantly decreased （P＜0.05 or P＜0.01）. Compared with the model group， rats in Shujin Jiannao Formula group showed decreased Zea-Longa scores and increased hindlimb suspension test scores （P＜0.05）； pathological damage in brain tissue alleviated， levels of IL-1β and TNF-α reduced， the number of Nissl-stained positive neurons in the cortex and hippocampal CA1 region increased， and the immunofluorescence intensity of NF200 and MBP， as well as the protein levels of PI3K and mTOR， significantly elevated （P＜0.05 or P＜0.01）. There were no statistically significant differences among the groups in body weight， body-turning time， or AKT protein levels in brain tissue （P＞0.05）. ConclusionShujin Jiannao Formula can improve the neurological function of rats with cerebral palsy， exert neurorestorative effects， and its mechanism of action may be related to the reduction of inflammatory response in brain tissue and the activation of the PI3K/AKT/mTOR signaling pathway.