The Protective Effects of Allopurinol, PAF Antagonist, LT Inhibitor, Superoxide Dismutase-Polyethylene Glycol, and Dexamethasone on Noise Induced Shift of Hearing Threshold in Guinea Pigs / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Prevention of noise induced hearing loss (NIHL) can be achieved by environmental control, however, recently, there are some suggestions for the protective effects of various drugs. To find an effective drug on the protection of NIHL, we investigated the protective effects of allopurinol, platelet activating factor (PAF) antagonist, leukotriene (LT) inhibitor, superoxide dismutase-polyethylene glycol (SOD-PEG), and dexamethasone on the noise induced threshold shift in guinea pigs. MAERIALS AND METHODS: Thirty healthy guinea pigs (60 ears) were divided into control and different treatment groups to consist of five guinea pigs each. Guinea pigs were exposed to 100 dBA white noise for eight hours. Auditory Brainstem Response (ABR) were recorded before and after the noise exposure. RESULTS: Changes in ABR thresholds were 48.1+/-9.6 dB SPL in the control group, 33.1+/-3.7 dB SPL in the allopurinol group, 39.37+/-17.8 dB SPL in the PAF antagonist group, 36.25+/-10.26 dB SPL in the LT inhibitor group, 38.0+/-13.98 dB SPL in the SOD-PEG group and 46.9+/-8.8 dB SPL in the dexamethasone group. Only the allopurinol group demonstrated significantly different threshold change compared to the control group. CONCLUSION: The results of this study suggest that allopurinol may be effective in protection of noise induced threshold shift, whereas PAF antagonist, LT inhibitor, SOD, dexamethasone may not be as effective.

Effect of Platelet-activating Factor on Hearing and Cochlear Hair Cells in Guinea Pigs / 대한이비인후과학회지

BACKGROUND AND OBJECTIVE: Inflammatory mediators released in the middle ear cavity appear to play an important role in the pathogenesis of otitis media and can cause functional as well as morphological changes in the inner ear. Recent studies have also implicated platelet-activating factor (PAF) to be involved in the pathogenesis of otitis media with effusion in addition to prostaglandines (PGs) and leukotrienes (LTs). PAF appears to be important in the acute inflammatory process of otitis media. The purpose of this study is to determine the effects of PAF placed on round window membrane (RWM) on hearing and cochlear hair cells in guinea pigs. MATERIALS AND METHODS: Control group and PAF group received RWM application of phosphate buffered saline (PBS) and PAF 1 ng/ml, respectively. Using auditory brainstem response (ABR), the hearing threshold of both group was measured every 2 hours duirng the 8 hours after placement of PBS or PAF. At the end of the eight hour, the harvested cochlears were prepared for scanning electron microscopy (SEM) study. RESULTS: There were mild to moderate increase in the ABR threshold from 2 to 8 hours after the application of PAF on the RWM in PAF group. When the threshold levels of the PAF group and the control group were compared, statistically significant differences were observed between the two groups (p<0.05). In SEM study, both inner and outer hair cells were found to be damaged. CONCLUSION: The exogenous PAF-induced hearing loss may have been due to the cochlear hair cell damage caused by these exogenous PAF. Thus, PAF may play an important role in the sensorineural hearing loss in otitis media with effusion.

Monitoring by ABR, TEOAE and DPOAE of Noise Induced Hearing Loss in Guinea Pig / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Noise-induced hearing loss (NIHL) is associated with the damage in outer hair cell (OHC). Otoacoustic emmision (OAE) is sensitive to the detection of damage in OHC. We intended to evaluate the usefulness of transient evoked OAE (TEOAE) and distortion product OAE (DPOAE) on early detection and monitoring of NIHL in guinea pigs. MATERIALS AND METHODS: Ten healthy guinea pigs were exposed to 90+/-3 dBA white noise 8 hours daily for 9 days. Daily measurements of auditory brainstem response (ABR), TEOAE and DPOAE were performed before the noise exposure and daily after the noise exposure. RESULTS: ABR threshold became poorer gradually until the 8th day of post noise exposure, and some recovery on the 9th day. Wave reproducibility on TEOAE demonstrated an abrupt decrement on the 6th post-exposure day, and a tendency of recovery from the 7th day. While the echo amplitudes in f2=2002 Hz and f2=4004 Hz showed similar pattern of change with ABR threshold, the echo amplitude of f2=6348 Hz showed marked decrease on the 5th day compared to two other frequencies (f2=2002 Hz, 4004 Hz). CONCLUSION: The results of this study suggest that wave reproducibility in TEOAE and echo amplitude in high frequency in DPOAE may have applicability for early detection and monitoring of NIHL.

Usefulness of Motor Control Test (MCT) to Evaluate Balance Function in Diabetic Patients with Neuropathy / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: It is important to adequately estimate the functional handicap of the patient with polyneuropathy. Computerized dynamic posturography (CDP) can be utilized in those patients to evaluate balance performance. But, so far, the majority of data are about sensory organization test (SOT) and the efficacy of motor control test (MCT) is not established. We performed this study in an attempt to estimate balance function in diabetic neuropathy patients using MCT, thereby confirm the usefulness of MCT in evaluating balance ability. SUBJECTS AND METHODS: Seventeen diabetic neuropathy patients (DM-NP), 9 non-neuropathy diabetic patients (DM-nonNP), and 22 non-diabetic normal persons as controls (nonDM) were included in this study. Postural responses to horizontal translation were assessed according to the MCT paradigm. The results were compared with the sway energy obtained during toes-up or toes-down perturbation. RESULTS: Latencies of backward translation were prolonged in DM-NP but not in DM-nonNP. Latencies of forward translation were prolonged both in DM-NP and DM-nonNP. No definite correlation could be drawn between the MCT and EMG latencies. DM-NP showed increased sway energy in toes-up and toes-down perturbation. MCT latencies and sway energy in perturbation showed significant correlation. CONCLUSION: MCT proved to be useful in evaluating balance performance in the patients with defective postural response as in diabetic neuropathy.