Jiunn Liang Wu

N-Acetyl-cysteine against noise-induced temporary threshold shift in male workers

Previous animal studies showed protective effects of antioxidant medicines against noise-induced hearing loss (NIHL). It is unclear whether antioxidants would protect humans from NIHL. We conducted a study to determine whether N-Acetyl-cysteine (NAC) protected men against noise-induced temporary threshold shift (TTS), and whether subgroups with genetic polymorphisms of glutathione S-transferase (GST) T1 and M1 responded to NAC differently. In this prospective, double-blind, crossover study, 53 male workers were randomly assigned to receive either NAC (1200 mg/day, 14 days) during the first period and placebo during the second period, or placebo during the first period and NAC during the second period. Dosing periods were separated by a washout period of 2 weeks. The hearing threshold changes were determined before and after each dosing period. Pre-shift hearing threshold for high frequencies was 19.1 dB. Daily exposure to noise ranged from 88.4 to 89.4 dB. The noise levels of different frequencies ranged from 80.0 to 89.4 dB with a peak-value at 4 kHz. NAC significantly reduced TTS (p = 0.03). When the participants were grouped by GST M1/T1 genotypes, the NAC effect was only significant among workers with null genotypes in both GSTM1 and GSTT1 (p = 0.004). NAC may prevent noise-induced TTS among occupationally noise-exposed men. The protective effect of NAC was more prominent in subjects with both GSTM1-null and GSTT1-null genotypes. (clinicaltrials.gov Identifier: NCT00552786).

Speech perception of Mandarin Chinese speaking young children after cochlear implant use: effect of age at implantation

OBJECTIVE The purposes of this study were to examine (1). whether the benefit of cochlear implants in Mandarin-speaking congenitally deaf children persists over a 2-year follow-up period, and (2). whether the age of the child at implantation affects the acquisition of speech perception by young deafened children. METHOD Sixteen congenitally deaf children received implants of Nucleus CI24M devices. Speech perception tests were conducted using the Mandarin Auditory Perception Test Battery at 6-month intervals after connection of the device. We determined the benefit of cochlear implants by monitoring percent correct scores between 12 and 24 months after implantation. Regression analysis was used to correlate the measures of progress and the age at implantation. RESULTS In the comparison of performance at 12 and 24 months post-connection, subjects performed significantly better at 24 than at 12 months in spondee, vowel, and consonant tests (P<0.05). In phrase and sentence tests, the mean score improved over time with device use, but the difference was not significant (P=0.066 and 0.067, respectively). However, no obvious improvement in average score was found in tone tests (P=0.386). Progress (improvement in speech perception) at 12 and 24 months had moderate negative correlations with age at implantation in spondee, vowel, phrase and sentence tests (P<0.05), but no correlation with age in consonant (P=0.20) and tone tests (P=0.26). CONCLUSION The result, in accordance with the reports on Western language-speaking children, showed cochlear implants increasingly benefit Mandarin-speaking congenitally deaf children over a 2-year post-implantation period. Because age at implantation negatively correlates with improved speech perception after implantation, congenitally affected children with profound deafness (if they cannot obtain enough benefit from hearing aids) should receive implants as early as possible.

The interplay between alcohol consumption, oral hygiene, ALDH2 and ADH1B in the risk of head and neck cancer

Alcohol consumption is an established risk factor for head and neck cancer (HNC). The major carcinogen from alcohol is acetaldehyde, which may be produced by humans or by oral microorganisms through the metabolism of ethanol. To account for the different sources of acetaldehyde production, the current study examined the interplay between alcohol consumption, oral hygiene (as a proxy measure for the growth of oral microorganisms), and alcohol‐metabolizing genes (ADH1B and ALDH2) in the risk of HNC. We found that both the fast (*2/*2) and the slow (*1/*1 + *1/*2) ADH1B genotypes increased the risk of HNC due to alcohol consumption, and this association differed according to the slow/non‐functional ALDH2 genotypes (*1/*2 + *2/*2) or poor oral hygiene. In persons with the fast ADH1B genotype, the HNC risk associated with alcohol drinking was increased for those with the slow/non‐functional ALDH2 genotypes. For those with the slow ADH1B genotypes, oral hygiene appeared to play an important role; the highest magnitude of an increased HNC risk in alcohol drinkers occurred among those with the worst oral hygiene. This is the first study to show that the association between alcohol drinking and HNC risk may be modified by the interplay between genetic polymorphisms of ADH1B and ALDH2 and oral hygiene. Although it is important to promote abstinence from or reduction of alcohol drinking to decrease the occurrence of HNC, improving oral hygiene practices may provide additional benefit.

Effects of Computer-Assisted Speech Training on Mandarin-Speaking Hearing-Impaired Children

The present study investigated whether moderate amounts of computer-assisted speech training can improve the speech recognition performance of hearing-impaired children. Ten Mandarin-speaking children (3 hearing aid users and 7 cochlear implant users) participated in the study. Training was conducted at home using a personal computer for half an hour per day, 5 days per week, for a period of 10 weeks. Results showed significant improvements in subjects’ vowel, consonant, and tone recognition performance after training. The improved performance was largely retained for 2 months after training was completed. These results suggest that moderate amounts of auditory training, using a computer-based auditory rehabilitation tool with minimal supervision, can be effective in improving the speech performance of hearing-impaired children.

Differential changes in Fos-immunoreactivity at the auditory brainstem after chronic injections of salicylate in rats.

In human, salicylate-induced tinnitus sometimes occurs a few days after its administration, but the chronic effects of salicylate in animal models are not fully known. In this study, we revealed the distribution of active cells in the rat auditory brainstem by staining an activity marker Fos-protein after multiple daily injections of salicylate. Experimental animals were first given five daily doses of sodium salicylate (250 mg/kg, i.p.). On day 6 they were placed inside a sound room for 8 h before sacrifice. Immunohistochemistry showed a significant increase in the number of Fos-positive cells at the inferior colliculus (IC), particularly its central division. At the cochlear nucleus (CN), only a few Fos-stains were found at the dorsal nucleus while no Fos-stain appeared at the ventral nucleus. The scarcity of Fos-stains at the CN reflected more a lack of external sound inputs than an adaptation in Fos-expression. Since Fos-stains in CN could still be induced on day 6 following brief tonal stimulation. Results are consistent with the hypothesis that salicylate-induced tinnitus is a phantom sound perception related to overactivity of cells at the IC.

Glutathione S-transferase M1, T1, and P1 polymorphisms as susceptibility factors for noise-induced temporary threshold shift.

The generation of reactive oxygen species (ROS) is thought to be part of the mechanism underlying noise-induced hearing loss (NIHL). Glutathione is an important cellular antioxidant that limits cell damage by ROS. We aimed to determine the effect of genetic polymorphisms of glutathione S-transferase (GST) T1, GSTM1, and GSTP1, on temporary threshold shift (TTS) in 58 noise-exposed male workers from a steel factory. The pre-shift hearing impairment at high frequency (HF, average of 3, 4, and 6kHz) was 30.7dB HL (S.D.=19.3). The amount of daily noise exposure was 83.0dBA (S.D.=5.0). Noise-induced TTS at HF by pure-tone audiometry (PTA) was related to the daily noise exposure (p<0.05). Based on combinatory analysis, we found that individuals carrying all genotypes with GSTT1 null, GSTM1 null, and GSTP1 Ile(105)/Ile(105) were more susceptible to NIHL. These results suggest that pre-shift hearing impairment and daily noise exposure had impacts on TTS at HF by PTA. In addition, GST genetic polymorphisms may modify the susceptibility to noise-induced TTS.

Tone discrimination and speech perception benefit in Mandarin-speaking children fit with HiRes fidelity 120 sound processing

Objective: To compare tone discrimination, speech perception, and general listening benefit in Mandarin-speaking children using standard HiRes and after 1, 3, and 6 months of HiRes 120 use. The HiResolution Bionic Ear is an implantable prosthesis designed to provide access to sound and to improve perception of speech via electrical stimulation of the auditory nerve. The newest sound-processing strategy is HiRes with Fidelity 120 (HiRes 120). In HiRes 120, the input signal is analyzed in greater spectral detail than with original HiRes to achieve a maximum of 120 spectral bands. HiRes 120 is expected to provide more benefit than the original HiRes because of the increased spectral resolution. Setting: Cochlear implant/tertiary referral center. Subjects: Seven children, aged 5 to 12 years, who had been implanted with a CII or 90K implant with a fully inserted electrode array and at least 10 contiguous programmable electrodes. Design: Tone discrimination, consonant identification, the Mandarin lexical neighborhood test (M-LNT), and the speech perception in noise (SPIN) tests were administered in 4 sessions: at a baseline visit with standard HiRes before being fit with HiRes 120 and at 1, 3, and 6 months after using HiRes 120. Each subject and his or her parents also completed a strategy preference questionnaire after using HiRes 120 for 6 months. Results: Statistically significant improvements from baseline with HiRes to 6 months with HiRes 120 were found for tone discrimination (61.4 to 73.2%, p = 0.006) and for SPIN low predictability (65.7 to 74.7%, p = 0.039). Mean score changes of 47.4 to 50.4% (p = 0.499) for consonant perception, 82.9 to 86.4% for M-LNT (easy words; p = 0.322), 77.1 to 81.0% for M-LNT (hard words; p = 0.423), and 72.3 to 78.5% for SPIN high predictability (p = 0.427) showed trends for improvement but were not statistically significant. Questionnaire results indicated that all children and parents preferred HiRes 120 to HiRes. Strength of preference was 8.9 for children and 8.1 for parents on a scale of 1 to 10 (1 = weak preference, 10 = strong preference). Conclusion: Taken together, the improved tone discrimination and speech perception results, along with subjective improvements in speech fluency, discrimination, and music appreciation, indicate a trend toward superior listening benefit with HiRes 120 compared with standard HiRes in Mandarin-speaking children.

Relationships among speech perception, self-rated tinnitus loudness and disability in tinnitus patients with normal pure-tone thresholds of hearing

Exactly how speech perception and tinnitus perception are related remains unclear. This study investigated how tinnitus alone affects speech perception and the relationship between speech perception, tinnitus loudness, and tinnitus disability. The Mandarin Speech Perception in Noise Test (MSPIN), Tinnitus Loudness Scaling (TLS), and Tinnitus Handicap Inventory (THI) were utilized to assess 20 tinnitus patients with normal hearing. The tinnitus group had a significantly lower MSPIN score than the control group (p < 0.01). TLS and THI scores were strongly correlated (r2: 0.534∼0.627, p < 0.05). Correlations between MSPIN and TLS or THI scores were not significant. Tinnitus loudness correlated well with tinnitus-related disability. Neither tinnitus loudness nor disability was strongly correlated with speech perception. In noisy environments, tinnitus sufferers had significantly poorer ability to recognize speech than control subjects.

Prevalence of hearing impairment in an adult population in southern Taiwan

The objective of this study was to estimate the prevalence of hearing impairment in a representative adult population in southern Taiwan and compare the results to those of similar studies in other countries. A stratified systematic cluster sample of 1140 residents, aged ≥20 years, of Tainan City was studied from 2001 to 2003. The test battery included otoscopy, pure-tone audiometry, and a questionnaire covering relevant personal, occupational, and family history. The hearing threshold level (HTL) was defined as the better ear pure-tone average (BPTA) (i.e. the average of hearing thresholds at frequencies 500, 1000, 2000, and 4000 Hz). The prevalence of hearing impairment was 21.4% (95% confidence interval: 19.3–23.7%) at BPTA ≥25 dB HTL. Middle ear disease was a significant risk factor for hearing impairment in addition to age and gender. The overall prevalence of hearing impairment may be higher in Taiwan (17.1%) than in western populations (11.5%), but differences in the definition of hearing impairment severity and variation in sex distribution among studies may account for this higher prevalence.

Tea Consumption and Risk of Head and Neck Cancer

Background The current study evaluated the association between tea consumption and head and neck cancer (HNC) in Taiwan, where tea is a major agricultural product and a popular beverage. Methods Interviews regarding tea consumption (frequency, duration, and types) were conducted with 396 HNC cases and 413 controls. Unconditional logistic regression was performed to estimate the odds ratio (OR) and 95% confidence interval (CI) of HNC risk associated with tea drinking, adjusted for sex, age, education, cigarette smoking, betel quid chewing, and alcohol drinking. Results A reduced HNC risk associated with tea drinking (OR for every cup per day = 0.96, 95% CI: 0.93–0.99; OR for ≧5 cups per day = 0.60, 95% CI: 0.39–0.94) was observed. The association was especially significant for pharyngeal cancer (OR for every cup per day = 0.93, 95% CI: 0.88–0.98; OR for ≧5 cups per day = 0.32, 95% CI: 0.16–0.66). A significant inverse association between HNC and tea consumption was observed particularly for green tea. Conclusions This study suggests that tea drinking may reduce the risk of HNC. The anticancer property of tea, if proven, may offer a natural chemopreventive measure to reduce the occurrence of HNC.