Hearing in ethnically different longshoremen

Assessment of auditory function in hepatitis “C” patients managed by combination of sofosbuvir and daclatsavir

Background

To evaluate the effect of daclatasvir and sofosbuvir on auditory function in hepatitis C patients. Thirty hepatitis C virus (HCV) patients were included in this study with age ranged from 22 to 55 years. All patients underwent full audiological evaluation before beginning and after completion of their treatment with combination of daclatasvir and sofosbuvir.

Result

When the results of audiological data were compared before and after treatment, we found that; there were statistically significant differences in the pure tone audiometry (PTA) threshold and ART bilaterally mainly in the high frequency region. Transient evoked otoacoustic emission (TEOAE) reproducibility showed a statistically significant difference bilateral. However, there was no statistically significant difference in the Auditory Brainstem Response (ABR) findings.

Conclusion and recommendations

The combination therapy of daclatasvir and sofosbuvir used in patients with HCV led to deterioration in the hearing threshold in the basic audiological tests (PTA and immitancemetry). In addition, it had an adverse effect on the cochlear OHCs, with no affection on auditory nerve, brain stem functions or in sub-thalamic function, it seems that it had no effect, we cannot confirm. The study evaluate hearing at the end of treatment immediately. We recommend performing a routine monitoring of auditory functions in HCV patients treated with daclatasvir and sofosbuvir combination by specialist for early detection of auditory changes to avoid further damage to auditory system.

The rat as a model for studying noise injury and otoprotection

A major challenge for those studying noise-induced injury pre-clinically is the selection of an animal model. Noise injury models are particularly relevant in an age when people are constantly bombarded by loud noise due to occupation and/or recreation. The rat has been widely used for noise-related morphological, physiological, biochemical, and molecular assessment. Noise exposure resulting in a temporary (TTS) or permanent threshold shift (PTS) yields trauma in peripheral and central auditory related pathways. While the precise nature of noise-related injuries continues to be delineated, both PTS and TTS (with or without hidden hearing loss) result in homeostatic changes implicated in conditions such as tinnitus and hyperacusis. Compared to mice, rats generally tolerate exposure to loud sounds reasonably well, often without exhibiting other physical non-inner ear related symptoms such as death, loss of consciousness, or seizures [Skradski, Clark, Jiang, White, Fu, and Ptacek (2001). Neuron 31, 537-544; Faingold (2002). Hear. Res. 168, 223-237; Firstova, Abaimov, Surina, Poletaeva, Fedotova, and Kovalev (2012). Bull Exp. Biol. Med. 154, 196-198; De Sarro, Russo, Citraro, and Meldrum (2017). Epilepsy Behav. 71, 165-173]. This ability of the rat to thrive following noise exposure permits study of long-term effects. Like the mouse, the rat also offers a well-characterized genome allowing genetic manipulations (i.e., knock-out, viral-based gene expression modulation, and optogenetics). Rat models of noise-related injury also provide valuable information for understanding mechanistic changes to identify therapeutic targets for treatment. This article provides a framework for selection of the rat as a model for noise injury studies.

Racial and gender effects on pure-tone thresholds and distortion-product otoacoustic emissions (DPOAEs) in normal-hearing young adults

This study examined racial and gender effects on behavioral thresholds and distortion-product otoacoustic emissions (DPOAEs) in the same subjects. Pure-tone behavioral thresholds and DPOAEs were measured in 60 young normal-hearing adult subjects (20 Caucasian, 20 Asian, 20 African-American, with ten females and ten males in each group). Behavioral thresholds were measured from 1000 through 16,000 Hz using Békèsy tracking. A DPOAE frequency sweep was measured with primary stimulus levels of L(1)/L(2)=60/45 dB SPL, and an f(2)/f(1) of 1.2 at discrete f(2) frequencies between 2000 through 12,000 Hz for each subject. Significant racial and gender differences in behavioral thresholds were found at 14,000 and 16,000 Hz, with the African Americans and females having the best hearing sensitivity. Based on the current results, similar findings for DPOAE frequency sweeps can be expected amongst different racial groups given that no significant differences were identified between the groups. To further define the effects of race and gender on auditory measures, future studies should include larger numbers of subjects, measurement of body size and middle ear reflectance, and examine emission generators.

Cisplatininduzierte Hörstörungen bei Kindern in Abhängigkeit von der Pigmentierung der Iris

BACKGROUND

Cisplatin is commonly used as a chemotherapeutic agent in the treatment of solid tumors. Ototoxicity is an important side-effect. Melanin in the inner ear either plays an otoprotective role or has a negative influence on hearing. The concentration of cochlear melanin correlates with its concentration in the iris.

PATIENTS AND METHODS

We retrospectively examined 65 children (37 males, 28 females, average age 7.5 years) treated with cisplatin at the University Clinic of Muenster, Germany. We checked whether their eye color could be inferred from the prevalence and extent of cisplatin-induced hearing loss.

RESULTS

We found a hearing loss of >20 dB in 29 light-eyed and in 21 dark-eyed patients. Seven light-eyed and eight dark-eyed patients did not suffer from hearing impairment. Using the chi(2)-test on these four parameters, we found no significant connection between iris pigmentation and the prevalence or extent of hearing loss, although light-eyed children (80.6%) suffered more from hearing loss than dark-eyed children (72.4%). After the end of therapy with cisplatin, the prevalence of hearing loss was 83.3% in children up to 6 years and 71.4% in children older than 6 years. The average cumulative dose of cisplatin was 372 mg/m(2) of body surface in children with hearing loss, compared to 390 mg/m(2) in children without hearing loss.

CONCLUSION

We found no significant correlation between iris pigmentation (eye color) and hearing loss. Cisplatin-induced hearing loss occurs frequently and requires repeated monitoring.

Cochlear function in young and adult Fischer 344 rats

Fischer 344 (F344) rats are often used as an animal model for investigation of the mechanisms underlying age-related hearing loss. The aim of this study was to assess cochlear function in young (1-month-old) and adult (6-month-old) F344 rats using recording of otoacoustic emissions and auditory brainstem responses (ABRs). The results were compared with control groups of Long Evans (LE) rats of the same ages. The results demonstrate a significant increase in the hearing threshold in F344 rats in comparison with LE rats, expressed mainly at low frequencies (1-2 kHz). In F344 rats, transient evoked otoacoustic emissions were not measurable and distortion product otoacoustic emissions could be detected within a frequency range of 2.4-6.3 kHz. Tympanometric measurements did not reveal any differences in middle ear parameters between F344 and LE rats. The amplitudes of click-evoked ABRs were significantly lower in 6-month-old F344 rats than in LE rats, but other parameters of the ABRs were almost identical in both rat strains. The results demonstrate a significant deficit in low-frequency hearing and altered otoacoustic emissions in both young and adult F344 rats, suggesting a defect of the inner ear sensory epithelium at the apical part of the cochlea.

Effects of tone burst frequency and intensity on the auditory brainstem response (ABR) from albino and pigmented rats

Young adult male Sprague-Dawley (SD) and Long-Evans (LE) rats were evaluated using the auditory brainstem response (ABR). ABRs were evoked by stimuli with intensities ranging from 15 to 100 dB peSPL. Stimuli were tone bursts of 2000, 4000 and 8000 Hz. As stimulus intensity decreased from 100 to 15 dB, the ABR peak latencies prolonged, interpeak latencies (IPLs) shortened and amplitudes decreased. As stimulus frequency decreased from 8000 to 2000 Hz, ABR latencies prolonged, amplitudes decreased and ABR thresholds increased. The longest IPLs were in response to the 4000 Hz tone bursts. SD rats had ABRs with shorter peak latencies, larger amplitudes and lower thresholds than LE rats. The IPLs usually did not show significant strain-dependent differences. Our observations on stimulus intensity and frequency are consistent with previous reports. Our observations also suggest that the SD (albino) rat has better auditory acuity than the LE (pigmented) rat over the frequency range of 2000 to 8000 Hz. This implies that previous concerns about the use of albino animals in audiological research are somewhat overstated.

The influence of inner ear melanin on susceptibility to TTS in humans

In order to investigate the function of the inner ear melanin, the relationship between skin pigmentation and noise-induced temporary hearing loss (TTS) was studied. Forty-four normal-hearing Caucasian subjects were divided into three groups according to their sun sensitivity. Hearing thresholds before and after exposure were ascertained with a computerized sweep frequency audiometer in the frequency range 2-8 kHz. The noise exposure consisted of a 1/3-octave band-filtered noise with a centre frequency of 2 kHz at 105 dB SPL for 10 min. The mean TTS in the frequency range 2-8 kHz showed statistically significant differences between the three groups, i.e. the most pigmented subjects developed least TTS, and the least pigmented subjects most TTS.

Audiologic abnormalities in cases of vitiligo

The audiologic function in 50 patients affected by vitiligo was studied. Eight patients (16%) had sensorineural hypoacusis when first seen by us. The relationships between melanocytes of the inner ear and auditory function are discussed.

Melanin capacity to accumulate drugs in the internal ear. A study on lidocaine, bupivacaine and chlorpromazine

The distribution and retention of labelled lidocaine, bupivacaine, and chlorpromazine to melanin in the internal ear after intravenous and intraperitoneal injection were examined by whole-body autoradiography. Both young pigmented hooded rats and albino rats were studied. In the pigmented rats chlorpromazine showed the greatest accumulation, which was more pronounced in the cochlea than in the vestibular portion. The other two substances were evenly distributed in the internal ear. After a single injection of chlorpromazine and of bupivacaine these substances were still bound to the melanin of the internal ear after 14 days, which was the longest survival time. Lidocaine, on the other hand, had disappeared after only 4 days. Strong uptake and retention of the three substances were observed in the eyes of pigmented animals. In albino animals there was very weak, transient uptake in the internal ear of chlorpromazine and bupivacaine, but not of lidocaine. In studies in vitro on isolated bovine eye melanin there was considerably greater adsorption of chlorpromazine than of lidocaine and bupivacaine. An uptake was noted in the human eye in experiments in vitro. Clinical tests revealed no acute or late damage to hearing or sight after large doses of lidocaine. The participation of melanin in different basal labyrinthine functions such as the energy transfer mechanism and the sound protective mechanism is discussed in the light of the results obtained. Further, the theory is put forward that the melanin affinity of certain substances can be of both therapeutic and ototoxic importance.

Albinism and auditory function in the laboratory mouse. II. Effects of acoustic priming and cross-fostering

Albino (c/c) and nonalbino (+/c and +/+) congenic C57BL/6J mice were examined for the effects of acoustic prestimulation (priming) on audiogenic seizures. While no genotypic-specific effects were noticed 1 day after priming, major effects were observed in separate groups of mice tested 5 days after priming. The c/c mice were most susceptible to audiogenic seizures, and no differences were observed between +/c and +/+ mice. While cross-fostering did not change this relationship, it provided protection from acoustic trauma is considered inconclusive because of the interaction of innate- and priming-induced audiogenic seizures in the +/c and c/c mice.

Albinism and auditory function in the laboratory mouse. I. Effects of single-gene substitutions on auditory physiology, audiogenic seizures, and developmental processes

The effects of single-gene albino (c/c) mutations on auditory behavior and physiology were examined in congenic C57BL/6J mice. At 16 days of age, the c gene was additively associated with both reduced auditory functioning and lower body weight: 16-day-old c/c mice had higher auditory evoked potential (AEP) thresholds than +/c mice, which, in turn, had higher thresholds than +/+ mice; +/c mice were also intermediate with regard to body weight. Since these differences had nearly disappeared by 21 days of age, it was concluded that the c genes worked in an additive fashion to delay development during the period previously (Henry, 1967) found critical for inducing susceptibility to audiogenic seizures. At 16 days of age, albino mice (c/c) displayed susceptibility to audiogenic seizures, but nonalbino genotypes (+/c and +/+) were immune to the convulsive effects of sound. This behavior appeared to be a recessive trait at this age. But 5 days later, the behavioral phenotype exhibited incomplete dominance, with the +/c genotype displaying audiogenic seizures intermediate to those seen in the susceptible c/c and the nonsusceptible +/+ genotypes. These behaviors were compared to the thresholds and peak-to-peak amplitudes of the AEP, as seen in the input-output functions. It is suggested that differential development of the auditory systems in these genotypes is causally related to susceptibility to audiogenic seizures.