Losartan Prevents Maladaptive Auditory-Somatosensory Plasticity After Hearing Loss via Transforming Growth Factor-β Signaling Suppression

OBJECTIVES: Hearing loss disrupts the balance of auditory-somatosensory inputs in the cochlear nucleus (CN) of the brainstem, which has been suggested to be a mechanism of tinnitus. This disruption results from maladaptive auditory-somatosensory plasticity, which is a form of axonal sprouting. Axonal sprouting is promoted by transforming growth factor (TGF)-β signaling, which can be inhibited by losartan. We investigated whether losartan prevents maladaptive auditory-somatosensory plasticity after hearing loss. METHODS: The study consisted of two stages: determining the time course of auditory-somatosensory plasticity following hearing loss and preventing auditory-somatosensory plasticity using losartan. In the first stage, rats were randomly divided into two groups: a control group that underwent a sham operation and a deaf group that underwent cochlea ablation on the left side. CNs were harvested 1 and 2 weeks after surgery. In the second stage, rats were randomly divided into either a saline group that underwent cochlear ablation on the left side and received normal saline or a losartan group that underwent cochlear ablation on the left side and received losartan. CNs were harvested 2 weeks after surgery. Hearing was estimated with auditory brainstem responses (ABRs). Western blotting was performed for vesicular glutamate transporter 1 (VGLUT1), reflecting auditory input; vesicular glutamate transporter 2 (VGLUT2), reflecting somatosensory input; growth-associated protein 43 (GAP-43), reflecting axonal sprouting; and p-Smad2/3. RESULTS: Baseline ABR thresholds before surgery ranged from 20 to 35 dB sound pressure level. After cochlear ablation, ABR thresholds were higher than 80 dB. In the first experiment, VGLUT2/VGLUT1 ratios did not differ significantly between the control and deaf groups 1 week after surgery. At 2 weeks after surgery, the deaf group had a significantly higher VGLUT2/VGLUT1 ratio compared to the control group. In the second experiment, the losartan group had a significantly lower VGLUT2/VGLUT1 ratio along with significantly lower p-Smad3 and GAP-43 levels compared to the saline group. CONCLUSION: Losartan might prevent axonal sprouting after hearing loss by blocking TGF-β signaling thereby preventing maladaptive auditory-somatosensory plasticity.

The Protective Effect of Egb 761 Against 3-Nitropropionic Acid-Induced Hearing Loss: The Role of Sirtuin 1

OBJECTIVES: Local administration of 3-nitropropionic acid (3-NP) to the inner ear induces sensorineural hearing loss. Several studies have shown the otoprotective effects of ginkgo biloba extract EGb 761. Moreover, EGb 761 has been reported to activate Sirtuin 1 (SIRT1). The present study was designed to investigate whether EGb 761 prevents 3-NP-induced sensorineural hearing loss and determine its effects on the expression of SIRT1. METHODS: Sprague Dawley rats were divided into four experimental groups: control group receiving vehicle of 3-NP, EGb group receiving EGb 761, 3-NP group receiving 3-NP, and EGb+3-NP group receiving EGb 761 and 3-NP. EGb 761 was given orally for 5 days. The 3-NP solution was injected into the tympanum 3 days after the start of EGb 761 administration. The auditory brainstem response was recorded before and after the injection. At 4 weeks after the administration of 3-NP or vehicle of 3-NP, cochleae were harvested, and hematoxylin and eosin staining and immunohistochemistry for SIRT1 antibody were performed. RESULTS: EGb+3-NP group showed significantly lower threshold shifts than 3-NP group. There was a significant preservation of type II fibrocytes and spiral ganglion cells in EGb+3-NP group than in 3-NP group. In EGb+3-NP group, there was a significantly greater number of SIRT1 immunopositive type II fibrocytes and spiral ganglion cells than in 3-NP group. Calculating the percentage of SIRT1 immunoreactive type II fibrocytes and spiral ganglion cells in viable type II fibrocytes and spiral ganglion cells, respectively, EGb+3-NP group showed significantly higher SIRT1 immunoreactive cells than 3-NP group. CONCLUSION: These results suggest that EGb 761 may prevent hearing loss induced by 3-NP in an acute ototoxic animal model, which appears to be related with SIRT1 expression.

Bilateral Cochlear Implantation in Facioscapulohumeral Muscular Dystrophy Presenting Sensorineural Hearing Loss / 대한이비인후과학회지

Facioscapulohumeral muscular dystrophy (FSHD) presents a muscular weakness in the face, shoulder girdle, and legs. In addition, bilateral, progressive, high-frequency sensorineural hearing loss (SNHL) can be expressed. A 3-year-old boy visited with bilateral facial paralysis and bilateral hearing loss. Audiological evaluations revealed bilateral, progressive, sloping SNHL and bilateral hearing aids was used for more than 3 years. Cochlear implantation was carried out on left side when he was 6 years old and on right side when he was 7 years old. Seven months after cochlear implantation on left side, his shoulder muscle weakness was found and the genetic analysis showed decreased D4Z4 repeat size in 4qA allele confirming a diagnosis of FSHD. After auditory rehabilitation using electroacoustic stimulation, his hearing and speech perception were much improved. This case suggests that cochlear implantation can be beneficial in patients with SNHL associated with FSHD.

Comparison of Free-Beam- and Fiber-Type CO₂ Laser Delivery Systems in Stapes Surgery

BACKGROUND AND OBJECTIVES: A free-beam-type CO₂ laser, which use a micromanipulator mounted on a microscope as the delivery system, has the merit of not being affected by hand tremor at the time of shooting. However, this delivery system has several disadvantages, including a restricted operation range and a risk of incorrect focusing. A fiber-type CO₂ laser uses a hand-held delivery system and has the opposite merits and demerits. We compared the results of stapes surgery with free-beam and fiber type delivery systems. SUBJECTS AND METHODS: The study enrolled 36 patients who underwent stapedotomy with free-beam- (n=26) or fiber- (n=10) type CO₂ lasers. The air-bone (AB) gap closure, bone conduction (BC) change, and operating time were evaluated. The AB gap closure was calculated by subtracting the preoperative BC thresholds from the postoperative air conduction thresholds. The BC change was calculated by subtracting the postoperative BC thresholds from the preoperative BC thresholds. RESULTS: The mean operating time was significantly (p=0.035) shorter in the fiber-type group (72.5±8.2 min) than in the free-beam-type group (80.5±11.4 min). The mean AB gap closure did not differ significantly (p=0.297) between the free-beamand fiber-type groups (5.8±10.1 and 1.4±6.8 dB, respectively). The mean BC change did not differ significantly (p=0.873) between the free-beam- and fiber-type groups (2.4±6.9 and 2.8±5.3 dB, respectively). The hearing outcomes did not differ significantly between the two groups. CONCLUSIONS: Operating times were significantly shorter using the fiber-type CO₂ laser, while hearing outcomes did not differ significantly between the two groups.

The Quality of Health Information on Allergic Rhinitis, Rhinitis, and Sinusitis Available on the Internet

PURPOSE: The internet has become one of the most important media outlets used to obtain health information. Therefore, the quality of health information available on the internet is very important. We evaluated the quality of internet-derived health information on allergic rhinitis, rhinitis and sinusitis and compared these results to those of previous studies performed five years ago. METHODS: The terms "allergic rhinitis (AR)", "rhinitis" and "sinusitis" were searched among the four most commonly used search engines in South Korea. These websites were evaluated according to the author, the Journal of the American Medical Association (JAMA) benchmarks, the DISCERN questionnaire and the Allergic rhinitis and its Impact on Asthma (ARIA) 2008 Update. RESULTS: A total of 120 websites were obtained and analyzed. For all diseases, "Oriental physician" had the largest portion (almost half of all websites), followed by "Western physician". Based on analyses using the JAMA benchmark, "Attribution" and "Disclosure" were ignored in almost all surveyed websites. According to the scores of the DISCERN question, the majority of websites did not supply appropriate references for their health information, and information on the negative aspects of treatment such as risks and uncertainty was not provided in several websites. In an analysis based on the ARIA 2008 Update concepts, 65% of websites pertaining to health information on AR contained unreliable information. CONCLUSIONS: The quality of health information on the internet was not acceptable. Thus, governmental regulation or control to improve the quality of health information is required.

Strategy for the Customized Mass Screening of Genetic Sensorineural Hearing Loss in Koreans

Hearing loss is one of the most common sensorineural disorder. More than half of congenital bilateral profound deafness cases have been estimated to be attributed to genetic cause. Identification of genetic cause can provide valuable information. We developed new diagnostic strategy combining phenotype-driven candidate gene approach and targeted exome sequencing to find out the causative mutation of hearing loss. The causative mutation detection rates of this strategy were 78.1% and 54.8% in Korean multiplex families and sporadic severe to profound hearing loss families, respectively. The most frequent causative genes of Korean multiplex families were SLC26A4 and POU3F4. The other causative genes were MRNR1, WFS1, COCH, TECTA, MYO6, COL11A2, EYA4, GJB3, OTOF, STRC, MYO3A, and GJB2. The most frequent causative gene of Korean sporadic severe to profound hearing loss families was SLC26A4 followed by GJB2, CHD7, and CDH23. Based upon the results, the value of this strategy as a diagnostic tool seems to be promising. Although whole genome and exome sequencing have advanced as the development of next-generation sequencing, this new strategy could be a good screening and diagnostic tool to find the causative mutations.

Post-Intubation Tracheoesophageal Fistula with Posterior Glottic Web

Tracheoesophageal fistula (TEF) after prolonged intubation could present as chronic aspiration and could be mistaken as unilateral or bilateral vocal fold palsy, especially when there was combined posterior glottic synechia. We present a case of post-intubation TEF which was successfully treated with tracheal resection and anastomosis with primary esophageal closure. The accompanying posterior glottic web was treated by endoscopic technique of web lysis, with topical application of mitomycin C solution.