Oak-Sung Choo

Autophagic flux, a possible mechanism for delayed gentamicin-induced ototoxicity.

Aminoglycoside antibiotics including gentamicin (GM) induce delayed ototoxic effects such as hearing loss after long-term use, unlike the early-onset ototoxicity caused by cisplatin. The purpose of the study was to identify the mechanism of the delayed GM-induced ototoxicity by exploring the role of autophagy in vitro and in vivo. Treating HEI-OC1 auditory cells with GM led to a time-dependent increase of the autophagosome marker LC3-II, which was accompanied by cell death. In contrast, cisplatin and penicillin caused a rapid increase and had no effect on LC3-II levels, respectively. LC3-II-expressing autophagosomes co-localized with the labeled GM. GM-treated autophagosomes expressed reduced levels of Rab7, which is necessary for the fusion of autophagosomes with lysosomes. When the autophagic flux enhancer rapamycin was applied to GM-treated cells, Rab7 and the lysosomal enzyme cathepsin D were upregulated, and increased cell survival was observed. In animal studies, the intraperitoneal injection of GM worsened hearing thresholds and induced the accumulation of LC3 in the organ of Corti. This hearing impairment was attenuated by rapamycin. These findings suggest that the delayed onset-ototoxicity of GM may be closely related to the accumulation of autophagosomes via impaired autophagy. This GM-induced auditory cell death could be inhibited by enhancing autophagic flux.

Steroid intracochlear distribution differs by administration method: Systemic versus intratympanic injection: Intracochlear Distribution of Steroid

Steroids have been widely used to treat inner‐ear diseases such as sudden sensorineural hearing loss, tinnitus, and Menieres disease. They can be given via either systemic or intratympanic (IT) injection. The purpose of the present study was to explore differences in intracochlear steroid distribution by the administration method employed (systemic vs. IT injection).

Differences in clinical characteristics and prognosis of sudden low- and high-frequency hearing loss

We compared the clinical characteristics between acute low‐ and high‐frequency hearing loss (LF and HF, respectively) patients, and the efficacy of three different treatment protocols (systemic steroids, intratympanic steroid injection, and combination therapy).

Osteogenesis for postoperative temporal bone defects using human ear adipose-derived stromal cells and tissue engineering: an animal model study

Mastoidectomy, the removal of infected mastoid bones, is a common surgical procedure for the treatment of chronic otitis media. Persistent and recurrent otorrhea and accumulation of keratin debris following open cavity mastoidectomy are still bothersome issues for both patients and otologists. In this study, we used human ear adipose-derived stromal cells (hEASCs) in combination with polycaprolactone (PCL) scaffolds and osteogenic differentiation medium (ODM) to regenerate temporal bone defects. The hEASCs showed stem cell phenotypes, and these characteristics were maintained up to passage 5. Mastoid bulla and cranial bone defects were induced in Sprague-Dawley rats using AgNO3 and burr hole drilling, respectively, and the rats were then divided into five groups: (1) control, (2) hEASCs, (3) hEASCs + ODM, (4) hEASCs + PCL scaffolds, and (5) hEASCs + PCL scaffolds + ODM. Osteogenesis was evaluated by micro-computed tomography and histology. Compared with the control group, the groups transplanted with hEASCs and PCL scaffolds had significantly higher bone formation along the periphery of the mastoid bulla area. Moreover, ODM synergistically enhanced bone formation in mastoid bulla defects. Our results suggest that combining hEASCs with PCL scaffolds represents a promising method for anatomical and functional reconstruction of postoperative temporal bone defects following mastoidectomy.

Temporary closure of congenital tracheoesophageal fistula with Fogarty catheter.

INTRODUCTION Congenital tracheoesophageal fistula (TEF) is a common anomaly, occurring in one of every 2,500 live births. Greater than 90% of cases involve esophageal atresia (EA). The most common form of TEF with EA is the upper esophagus ending as a blind pouch and TEF connecting to distal esophagus a few millimeters above the carina. The exact cause is not yet completely understood. In recent years, the survival rate of the patients with TEF improved up to 90% due to advances in neonatal intensive care, nutritional support, and newborn anesthesia. However, in rare cases, persistent aspiration and recurrent pneumonia caused by the existing fistula induce poor medical conditions, despite intensive care and support, disabling the neonates to withstand corrective surgery performed under general anesthesia for several hours. For these patients, it is very important to allow sufficient time to recover lung function and improve their medical condition. The Fogarty catheter, developed by Dr. Thomas J. Fogarty in 1963, is a type of catheter that is used for various medical applications including removal of thrombi or emboli from blood vessels, or removal of stones from the urinary tract and gall bladder. The Fogarty catheter includes a small inflatable balloon at the catheter tip. Once the catheter has been inserted and placed, the balloon is inflated with air or a sterile fluid. It has been used to seal off various fistulas, including carotid cavernous fisulta, arteriovenous fistula, and bronchopleural fistula. We conceived the idea that the ballooning of a Fogarty catheter can provide durable blockage of the fistula opening for the temporary separation of the airway and gastrointestinal (GI) tract. Here, we present our experience with bronchoscopic insertion of a Fogarty catheter for temporary occlusion of TEF to facilitate ventilation and medical care until corrective surgery of the anomaly.

Two Cases of Acute Mastoiditis with Subperiosteal Abscess

The incidence of mastoiditis in pediatric age has consistently increased over the last two decades due to increase of antibiotic-resistant bacteria. Compared to young patients, occurrence of acute otitis media complications such as acute mastoiditis and subperiosteal abscess is relatively low in adults. Various treatments for acute mastoiditis with subperiosteal abscess such as tympanostomy tube insertion, intravenous antibiotics, and postauricular incision and drainage have avoided the morbidity and necessity of mastoid surgery. Recently, many studies have indicated mastoidectomy only in cases of severe complications or failure of disease improvement after antibiotic treatment and myringotomy. In this report, we present two cases of successful treatment of subperiosteal abscess and discuss the management of acute mastoiditis with subperiosteal abscess in both child and adult.

Cascade recurring deep networks for audible range prediction

BackgroundHearing Aids amplify sounds at certain frequencies to help patients, who have hearing loss, to improve the quality of life. Variables affecting hearing improvement include the characteristics of the patients’ hearing loss, the characteristics of the hearing aids, and the characteristics of the frequencies. Although the two former characteristics have been studied, there are only limited studies predicting hearing gain, after wearing Hearing Aids, with utilizing all three characteristics. Therefore, we propose a new machine learning algorithm that can present the degree of hearing improvement expected from the wearing of hearing aids.MethodsThe proposed algorithm consists of cascade structure, recurrent structure and deep network structure. For cascade structure, it reflects correlations between frequency bands. For recurrent structure, output variables in one particular network of frequency bands are reused as input variables for other networks. Furthermore, it is of deep network structure with many hidden layers. We denote such networks as cascade recurring deep network where training consists of two phases; cascade phase and tuning phase.ResultsWhen applied to medical records of 2,182 patients treated for hearing loss, the proposed algorithm reduced the error rate by 58% from the other neural networks.ConclusionsThe proposed algorithm is a novel algorithm that can be utilized for signal or sequential data. Clinically, the proposed algorithm can serve as a medical assistance tool that fulfill the patients’ satisfaction.

Infratemporal fossa cellulitis caused by a remnant iatrogenic foreign body after a bimaxillary operation.

Infratemporal fossa cellulitis is rare and mostly occurs because of sinusitis and dental procedures. Furthermore, cellulitis caused by iatrogenic foreign bodies is very rare. A 28-year-old woman who had previously undergone cosmetic bimaxillary operation visited our hospital complaining of left facial swelling, oppressive pain, and nasal obstruction since 2 years. She had been attending another clinic, but despite having additional procedures and taking medications, her symptoms persisted. A subsequent operation was performed, during which we found a remnant surgical gauze from the previous operation, which was decomposed and trapped around the necrotic soft tissue and had eroded the bony structure around the pterygoid fossa. The material was successfully removed by endoscopic surgery, and the necrotic tissue was debrided. After the operation, all symptoms disappeared, and the patient was discharged without sequelae. During any procedure, surgeons must meticulously check for remnant material. Additionally, physicians must carefully note patient history and perform a physical examination, even in patients without serious symptoms. We report a case of advanced infratemporal fossa cellulitis due to remnant gauze material during a previous operation that was undetected.

Efficacy of Tympanoplasty Without Mastoidectomy for Treating Chronic Otitis Media in Patients With Mastoid Cavity Opacification in Temporal Bone Computed Tomography Findings

Objectives Combined mastoidectomy is generally preferred to tympanoplasty alone when treating patients with chronic otitis media (COM), particularly when temporal bone computed tomography (TBCT) shows that the mastoid cavity contains opacification of soft tissue density. However, in cases with Eustachian tube dysfunction, a mastoid cavity volume may be a burden to its function. We hypothesized that tympanoplasty alone might be better than tympanoplasty combined with mastoidectomy because soft tissue in the mastoid cavity is a sequel to a protective physiological response. Thus, we explored the efficacy of tympanoplasty without mastoidectomy in COM patients exhibiting mastoid air cell opacification on TBCT. Methods Between 2010 and 2014, a total of 33 patients, diagnosed with COM and with evidence of mastoid cavity opacification on TBCT, underwent tympanoplasty without mastoidectomy. All ears had been dry for ≥3 months before surgery. All procedures were performed by the same surgeon. We retrospectively analyzed the preoperative otoscopic findings, pre- and postoperative pure tone averages (PTAs; the mean of the values at 0.5, 1, 2, and 4 kHz), surgical procedures, and complications or recurrence. Results Of the 33 patients, 28 (84.8%) exhibited hearing improvement after surgery. The mean pre- and postoperative PTAs were 46.9±21.2 dB and 29.4±17.0 dB, respectively (P<0.001). The air-bone gap decreased from 25.7±10.7 dB to 10.3±8.7 dB (P<0.001). Thirty-two patients (97.0%) did not develop any COM recurrence or cholesteatoma; one patient developed attic retraction of the tympanic membrane. Other minor complications were transient otorrhea caused by myringitis (two cases) and a pinpoint perforation (one case). Conclusion Tympanoplasty alone, i.e., without mastoidectomy, may adequately control COM, if it shows dry-up status for at least 3 months even though mastoid cavity opacification is detected in TBCT.

Drugs for hyperlipidaemia may slow the progression of hearing loss in the elderly: A drug repurposing study

Hearing loss in the elderly causes communication difficulties, decreased quality of life, isolation, loneliness and frustration. The aim of this study was to identify the modifiable variables that may affect the progression of hearing loss in the elderly. A case‐control study was conducted using two data sets. Data were extracted from the health examination survey of Ajou University Hospital (2010‐2014) and the Korea National Health and Nutrition Examination Survey (2009‐2012) data sets. Audiometry data were evaluated according to variables such as age, sex and drug use for underlying diseases. Logistic regression analysis was performed on the entire study population, and middle‐aged and elderly groups using odds ratios (ORs). Factors including older age, female gender and diabetes mellitus were significantly associated with hearing levels in all age groups (OR [95% confidence interval, 95% CI], 0.375 [0.388‐0.415], 1.202 [1.195‐1.208], and 1.427 [1.183‐1.721], respectively). However, when the results from the middle‐aged and elderly groups were compared, medication for hyperlipidaemia had a significantly positive effect on the preservation of hearing in the elderly group (OR [95% CI], 0.713 [0.567‐0.897]), but not in the middle‐aged group (OR [95% CI], 0.967 [0.791‐1.183]). People, especially those in the elderly group, exposed to medication for hyperlipidaemia are likely to have better hearing than those not exposed to such drugs. Thus, drugs prescribed for hyperlipidaemia may maintain hearing in the elderly. However, to overcome potential confounding—by unmeasured variables—that is present in this study, further studies must be performed with more elaborate research design and methodology.