Biomedical subjects

Eui-Cheol Nam

Publications and source records attributed to Eui-Cheol Nam.

4 recordsLinked to original sources

PubMed2005

Electrocochleography is more sensitive than distortion-product otoacoustic emission test for detecting noise-induced temporary threshold shift.

OBJECTIVE: We investigated and compared the usefulness of the electrocochleography and distortion product otoacoustic emission tests for detecting the earliest noise-induced damage by analyzing the sensitivity and specificity of the 2 tests. STUDY DESIGN: A prospective study. METHODS: After listening to music at 90.3 +/- 4.2 dB in the same night-club for 2 hours continuously, 23 healthy normal ears experienced a temporary threshold shift exceeding 5 dB. Pure-tone audiometry, the distortion product otoacoustic emission test, and electrocochleography were performed before, immediately after, and 24 hours after the exposure. RESULTS: Before exposure, the measured distortion product/noise floor was 9.8 +/- 10.4, 23.5 +/- 6.4, 18.7 +/- 6.4, and 19.1 +/- 5.6 dB sound pressure level (SPL) at frequencies of 1, 2, 3, and 4 kHz, respectively. Immediately after exposure, it decreased significantly at 2, 3, and 4 kHz to 16.6 +/- 7.6, 12.5 +/- 6.8, and 14.8 +/- 7.7 dB SPL, respectively. Marked increases in the amplitude of the summating potential and summating potential/action potential ratio were recorded from 0.15 +/- 0.06 to 0.32 +/- 0.11 and 0.23 +/- 0.06 to 0.44 +/- 0.08, respectively. The respective sensitivity and specificity of electrocochleography were 76.7% to 88.5% and 91.0% to 100%. Those of the distortion product otoacoustic emission test were 54.8% to 62.2% and 75.5% to 87.0%, respectively. CONCLUSION: Electrocochleography appears to provide more sensitive and specific information than the distortion product otoacoustic emission test for detecting a noise-induced temporary threshold shift.

Adult↗

PubMed2005

Is it necessary to differentiate tinnitus from auditory hallucination in schizophrenic patients?

Although the definitions of subjective tinnitus and auditory hallucination are very similar, the origins and underlying causes of each symptom clearly differ. This study examined whether the differentiation of tinnitus from auditory hallucination is necessary for the proper management of these symptoms in schizophrenic patients. We investigated the characteristics of auditory hallucinations in 15 schizophrenic patients, and measured their pure-tone hearing levels and auditory brainstem responses (ABR). The average hearing level was 20.6 +/- 16.2 dB, with a mild decrease at high frequencies. We classified the patients into three groups: pure hallucination, tinnitus, and hallucination plus tinnitus. Eight patients (53.3 per cent) complained of pure hallucination and only one of them had a mild hearing loss. Hearing deficits were observed in six of seven tinnitus patients. Abnormal findings of ABR were found only in the pure hallucination group. The results suggest that tinnitus should be differentiated from auditory hallucination in the evaluation of schizophrenic patients.

Adult↗

PubMed2004

The effect of cellular retinoic acid binding protein-I expression on the CYP26-mediated catabolism of all-trans retinoic acid and cell proliferation in head and neck squamous cell carcinoma.

The aim of this study was to confirm if catabolism of all-trans retinoic acid (RA) is enhanced by type I cellular retinoic acid binding protein (CRABP-I) expression and to investigate the effect of this enhanced catabolism on cell proliferation of the head and neck squamous cell carcinoma (HNSCC) cell line, AMC-HN-7. We also analyzed the effects of CRABP-I on RA-induced retinoic acid receptor (RAR) activity. The expression of the CRABP-I in stably transfected AMC-HN-7 cell lines (HN7-BPIa and HN7-BPIb) resulted in a lower sensitivity to administered RA compared with that of controls in a clonogenic assay. HN7-BPIs cells showed an increased amount of polar metabolites of RA in thin-layer chromatography. The transcriptional activity of the reporter plasmid RARE(DR5)-tk-CAT after the treatment of RA was lesser in HN7-BPIs than in controls. These results suggest that the increased CYP26-mediated catabolism of RA by CRABP-I transfection might decrease the amount of RA that is accessible to the nuclear receptors and make HNSCC cells resistant to RA.

Blotting, Western↗

PubMed2004

Extratympanic electrocochleographic changes on noise-induced temporary threshold shift.

OBJECTIVE: Electrocochleography (ECoG) is a sensitive evoked-response test for evaluating changes in cochlear function. We investigated the extratympanic ECoG in a noise-induced temporary threshold shift (TTS) to evaluate the usefulness of ECoG in the early detection of noise-induced hearing loss (NIHL). STUDY DESIGN AND METHODS: In a prospective analysis, 15 healthy ears were exposed to 90.3- to 105.0-dB noise for 3 hours in the same computer-game arcade. Pure-tone audiometry and ECoG were performed before, immediately after, and 24 hours after the exposure. RESULTS: Before the exposure, the average hearing level was 5.8 +/- 2.7 dB, which increased significantly to 12.8 +/- 2.8 dB immediately after exposure. A marked increment in the SP/AP (summating potential/action potential) ratio was observed with the TTS. The mean ratio was 0.22 +/- 0.11 before the exposure, 0.46 +/- 0.18 in the TTS phase, and 0.20 +/- 0.11 after resolution. CONCLUSION: The results of this study suggest that the SP/AP ratio is useful for the early detection and monitoring of NIHL.

Action Potentials↗