Audiologic Characteristics of Hearing and Tinnitus in Occupational Noise-Induced Hearing Loss.

BACKGROUND: To analyze the characteristics of patients with noise-induced hearing loss (NIHL) by comparing audiologic test findings between groups with and without tinnitus. METHODS: This study involved patients with noise-induced hearing loss (NIHL) who presented to the otolaryngology clinic between January 2016 and April 2019. Tests including 3 pure-tone audiometry (PTA) tests at intervals greater than 1 week, and auditory brainstem response (ABR) were evaluated and patients were screened for tinnitus. The tinnitus patients had otoacoustic emission. Comparison was done between the tinnitus group and the group without tinnitus. RESULTS: Of the 730 subjects with NIHL, 389 had tinnitus. PTA showed significantly higher thresholds at 2 kHz to 8 kHz in the tinnitus group. Although ABR tests tended to show more prolonged I, III, and V latency in the tinnitus group, the differences were not statistically significant. Distortion product otoacoustic emissions (DPOAE) showed more abnormalities at 3 kHz, and 4 kHz than at 1 kHz and 2 kHz. Transient otoacoustic emission (TEOAE) showed abnormal findings in both ears. CONCLUSION: In NIHL, hearing loss was more severe in patients with, than without tinnitus. DPOAE showed more abnormalities at 3 kHz, 4 kHz, and 6 kHz than at 1 kHz and 2 kHz, and TEOAE was abnormal at all frequencies.

Stereoselective dihydroxylation reactions of gamma-amino-alpha,beta-unsaturated esters via their aryl ketimine derivatives.

OsO4-catalysed dihydroxylation reactions of the aryl ketimine derivatives of (E)-gamma-amino-alpha,beta-unsaturated esters gave anti selectivity ranging from 6.7 : 1 to 19 : 1, whereas the opposite syn selectivity was consistently observed with those of (Z)-gamma-amino-alpha,beta-unsaturated esters (5.4 : 1 to > 100 : 1).