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Objective To study the effects of epigallocatechin-3-gallate(EGCG) on noise-induced cochlear injuries.Methods A total of 45 guinea pigs were divided into three groups: the EGCG+noise exposure group, the normal saline+noise exposure group, and the control group.15 Guinea pigs in each group.For EGCG administration, the guinea pigs were given abdominal injection (25 mg/1 000 g) 1 day before and 1 hour before noise exposure (120 dB SPL, 4 h),where for the control group, the guinea pigs received nothing.The hearing function was detected by the auditory brainstem response (ABR) recording after noise exposure immediately, and at 1,3,7, and 14 days after noise exposure.On the 14th day, the cochlea were isolated, and the cells morphology of basal membrane and vascular stria, the outer hair cell movement protein (Prestin), and the 3-nitrotyrosine (3-NT) were examined by immunohistochemistry staminy.Results After noise exposure, ABR thresholds in the EGCG group were higher than that of in the control group(P<0.05), but lower than the normal saline group(P<0.05),though the differences between the other two groups became smaller from day 3.Immunohistochemistry (IHC) staining showed that the three rows of outer hair cells of the control group with Prestin protein stained were arranged neatlyand lack of cell absent, and 3-NT was mainly distributed in the cytoplasm and epidermis.Compared with the normal saline + noise group, after noise exposure, the outer hair cells of EGCG + noise group were in better shape, and prestin staining was clear.Besides, the basal membrane and vascular stria were slightly damaged, the cells arranged neatly and the 3-NT distribution was decreased.Conclusion Preventive intraperitoneal injection of EGCG may reduce cochlea damage caused by noise.
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<p><b>OBJECTIVE</b>To analyze the clinical characteristics of unilateral conductive hearing loss with intact tympanic membrane, and summarize the key diagnostic points, differential diagnosis and observe the effects of surgical treatment.</p><p><b>METHODS</b>We reviewed data from 82 patients with unilateral conductive hearing loss with intact tympanic membranes who accepted the exploratory tympanotomy from April 2011 to September 2013. There were 41 males and 41 females, aged from 7 to 66( averaged 26.5±13.7)years, with a history of one month to 50 years. The history, clinical symptoms, audiological evaluation, high resolution temporal bone CT, the results of surgical exploration and hearing reconstruction were analyzed.</p><p><b>RESULTS</b>The exploratory tympanotomy revealed 43 cases of congenital middle ear malformations (52.4%), 22 cases of otosclerosis (26.8%), eight cases of congenital cholesteatoma (9.8%), six cases of trauma induced conductive hearing loss (7.3%), three cases of congenital ossicular malformations with congenital cholesteatoma (3.7%). Progressive hearing loss was common in patients with otosclerosis and congenital cholesteatoma, and patients with congenital middle ear malformations described their hearing loss since childhood. High resolution temporal bone CT of congenital middle ear malformation, trauma induced conductive hearing loss, congenital cholesteatoma diagnosis rate was 40.0%, 50.0%, and 83.3% respectively. The preoperative air-conductive threshold of patients with absence of the oval window were increased to (66.9±1.1)dBHL, the preoperative bone-conductive threshold achieved (28.3±10.4)dBHL at 2 000 Hz. While patients with stapes fixation and that with ossicular chain discontinuity were (27.2±9.7)dBHL and (17.8±8.8)dBHL(P=0.000)respectively. Through the tympanic exploration with endaural incision under the microscope, different hearing reconstruction were applied according to different lesions. After the operation, the hearing level of 52 patients with return visit were improved, the mean air-conductive threshold were decreased from (60.0±11.4)dBHL to (32.2±12.1)dBHL(P=0.000); and the mean ABG were decreased from (43.2±12.0)dB to (16.3±9.4)dB(P=0.000).</p><p><b>CONCLUSIONS</b>Congenital middle ear malformations, otosclerosis, congenital cholesteatoma are the most common causes in unilateral conductive hearing loss with an intact tympanic membrane. The diagnosis rate can be improved by analyzing the clinical features. Through exploratory tympanotomy and hearing reconstruction, we can clarify the diagnosis and achieve a satisfying hearing recover.</p>