Protective effect of peperphentonamine injection through the otocyst against gentamicin- induced cochlear damage in guinea pigs / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the relationship of gentamicin-induced cochlear damage with autophagy-related protein LC3, beclin1, Na(+-)K(+-)2Cl(-) cotransporter (NKCC1) mRNA and endothelin-1 (ET-1), and investigate the protective mechanism of PPTA against gentamicin-induced cochlear damage.</p><p><b>METHODS</b>Sixty guinea pigs were randomly divided into control group (with saline and artificial perilymph injections), model group (with gentamicin and artificial perilymph injections), concurrent treatment group (with gentamicin and PPTA injections), model control group (with artificial perilymph injection 7 days after gentamicin injection) and delayed treatment group (with PPTA injection 7 days after gentamicin injection). Saline and gentamicin (160 mg/kg) were injected intraperitoneally, and artificial perilymph and PPTA were injected into the otocysts on a daily basis for 7 consecutive days. Hearing impairment of the guinea pigs was analyzed with ABR, and the protein expressions of beclin1 and LC3 in cochlear tissue were tested. The expression of NKCC1 mRNA was detected with RT-PCR, and the expression of ET-1 was detected immunohistochemically.</p><p><b>RESULTS</b>The ABR thresholds in the model group and model control group were similar (P>0.05) , but significantly higher than those in the other 3 groups (P<0.05); the threshold was significantly lower in concurrent treatment group than in delayed treatment group (P<0.05). Compared with those in the other 4 groups, the expressions of LC3 II, beclin1, and NKCC1 mRNA were significantly increased in the model group (P<0.05); and those in delayed treatment group were significantly lower than those in the model control group (P<0.05). The expressions of ET-1 in the Corti organ, striavascularis and spiral ganglion were significantly higher in the model group but significantly lower in the control group than those in the other 4 groups; ET-1 expression was significantly lower in delayed treatment group than in the model control group.</p><p><b>CONCLUSION</b>PPTA offers protection against gantamicin-induced cochlear damage in guinea pigs by inhibiting cell autophagy and suppressing of NKCC1 and ET-1 expressions. Early intervention with PPTA produces better therapeutic effect, suggesting that gantamicin causes irreversible injury of the auditory cells.</p>

Tragus cartilage tympanoplasty for treatment of adhesive otitis media / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the efficacy of cartilage tympanoplasty in the treatment of adhesive otitis media.</p><p><b>METHODS</b>From June to October, 2008, 18 patients with adhesive otitis media (18 ears) were treated with tragus cartilage tympanoplasty. The air-bone gap changes and the self-perceived symptomatic improvement were evaluated at 1 month and 1 year after the operation.</p><p><b>RESULTS</b>All the patients showed dry ear within 6 weeks after the operation. Tympanic membrane healing was achieved in 17 cases, and 1 case presented with a inferior-anterior fissure in the tympanic membrane. With the average preoperative air-bone gap (at 0.25, 0.5, 1.0, and 2.0 kHz) of 44.65 dB, the patients showed an obvious decrease of the air-bone gap by over 10 dB at 1 month after the operation and by over 25 dB at one year. Symptomatic improvements were achieved in these cases, including alleviated ear discomforts (3/15 cases), total tinnitus relief (1/11 cases), and alleviated tinnitus (10/11 cases). High-frequency tinnitus was noted in 1 case (1/7 cases), and the tympanic membrane appeared normal in 17 cases.</p><p><b>CONCLUSION</b>Tympanic membrane reconstruction using the tragus cartilage can be feasible for treatment of secretory otitis media, but the surgical indications should be carefully controlled.</p>

Therapeutic effect of insulin-like growth factor-1 injection into the inner ears through scala tympani fenestration on gentamicin-induced hearing loss in guinea pigs / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the therapeutic effect of insulin-like growth factor-1 (IGF-1) injection into the inner ears through a scala tympani fenestration on sensorineural deafness in a guinea pig model of gentamicin-induced hearing loss.</p><p><b>METHODS</b>Twenty guinea pigs with gentamicin-induced hearing loss were randomized equally into IGF-1 group and control group. In both groups, scala tympani fenestration was performed for injection of IGF-1 (10 microl) or artificial perilymphatic fluid (10 microl). Auditory brainstem responses (ABR) test was performed before and 7 and 14 days after surgery, respectively, and the cochlea was removed by decollation of 3 guinea pigs from each group after ABR test for observing the changes in the hair cells using scanning electron microscope.</p><p><b>RESULTS</b>Significant reduction in the ABR response threshold (RT) occurred in IGF-1 group 7 and 14 days after the surgery, and on day 14, ABR RT showed significant difference between IGF-1 group and the control group. Scanning electron microscopy revealed severer damages of the hair cells in the control group, and in the IGF-1 group, finger-like microvilli was detected on the surface of the damaged hair cells.</p><p><b>CONCLUSION</b>IGF-1 injection in the inner ear through the scala tympani fenestration may ameliorate the damages of the auditory function and relieve sustained toxicity of gentamicin in guinea pigs possibly by protection and partial repair of the damaged cochlea hair cells as well as protection of the afferent nerves.</p>

Auditory brainstem response in normal guinea pigs and those with gentamicin-induced hearing loss under awake and anesthetic conditions / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the alterations of auditory brainstem response (ABR) in guinea pigs with gentamicin-induced hearing loss under awake and anesthetic conditions.</p><p><b>METHODS</b>We recorded the ABR in 20 normal guinea pigs and 20 with gentamicin-induced hearing loss before and after anesthesia for statistical analysis.</p><p><b>RESULTS</b>No significant difference was observed in the waveform, response threshold (RT), I and III peak latencies (PL), I-III interpeak latencies (IPL) of ABR between awake and anesthetic conditions in normal guinea pigs (P>0.05), nor did gentamicin-induced hearing loss showed obvious impact on the ABR parameters (P>0.05).</p><p><b>CONCLUSION</b>No significant ABR alterations occur under awake and anesthetic conditions in either normal guinea pigs or those with hearing loss, therefore ABR test can be performed without anesthesia to ensure the success and error minimization of the experiment.</p>