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421 result(s) for "Kang, Byung Chul"
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Cochlear Implantation in Postlingually Deaf Adults is Time-sensitive Towards Positive Outcome: Prediction using Advanced Machine Learning Techniques
Given our aging society and the prevalence of age-related hearing loss that often develops during adulthood, hearing loss is a common public health issue affecting almost all older adults. Moderate-to-moderately severe hearing loss can usually be corrected with hearing aids; however, severe-to-profound hearing loss often requires a cochlear implant (CI). However, post-operative CI results vary, and the performance of the previous prediction models is limited, indicating that a new approach is needed. For postlingually deaf adults (n de120) who received CI with full insertion, we predicted CI outcomes using a Random-Forest Regression (RFR) model and investigated the effect of preoperative factors on CI outcomes. Postoperative word recognition scores (WRS) served as the dependent variable to predict. Predictors included duration of deafness (DoD), age at CI operation (ageCI), duration of hearing-aid use (DoHA), preoperative hearing threshold and sentence recognition score. Prediction accuracy was evaluated using mean absolute error (MAE) and Pearson’s correlation coefficient r between the true WRS and predicted WRS. The fitting using a linear model resulted in prediction of WRS with r  = 0.7 and MAE = 15.6 ± 9. RFR outperformed the linear model ( r  = 0.96, MAE = 6.1 ± 4.7, p < 0.00001). Cross-hospital data validation showed reliable performance using RFR ( r  = 0.91, MAE = 9.6 ± 5.2). The contribution of DoD to prediction was the highest (MAE increase when omitted: 14.8), followed by ageCI (8.9) and DoHA (7.5). After CI, patients with DoD < 10 years presented better WRSs and smaller variations (p < 0.01) than those with longer DoD. Better WRS was also explained by younger age at CI and longer-term DoHA. Machine learning demonstrated a robust prediction performance for CI outcomes in postlingually deaf adults across different institutes, providing a reference value for counseling patients considering CI. Health care providers should be aware that the patients with severe-to-profound hearing loss who cannot have benefit from hearing aids need to proceed with CI as soon as possible and should continue using hearing aids until after CI operation.
Dexamethasone treatment of murine auditory hair cells and cochlear explants attenuates tumor necrosis factor-α-initiated apoptotic damage
The most common cause of sensorineural hearing loss is damage of auditory hair cells. Tumor necrosis factor-alpha (TNF-α) is closely associated with sensorineural hearing loss. The present study examined the preconditioning effect of dexamethasone (DEX) on TNF-α-induced ototoxicity in mouse auditory hair cells (HEI-OC1) and cochlear explants. Treatment of HEI-OC1 with 10 ng/ml TNF-α for 24 h decreased cell viability, increased the accumulation of reactive oxygen species (ROS), and induced caspase-mediated apoptotic signaling pathways. Pretreatment with 10 nM DEX for 6 h before TNF-α exposure restored cell viability, decreased ROS accumulation, and attenuated apoptotic signaling activation induced by TNF-α. Incubation of cochlear explants with 20 ng/ml TNF-α for 24 h resulted in significant loss of both inner hair cells (IHCs) and outer hair cells (OHCs) and an increase in apoptotic activation accessed by annexin V staining. The cochlear explants pre-incubated with 10 nM DEX attenuated TNF-α ototoxicity in both IHCs and OHCs and apoptotic cell death. These results indicated that DEX plays a protective role in ototoxicity induced by TNF-α through attenuation of caspase-dependent apoptosis signaling pathway and ROS accumulation.
Percutaneous Treatment of Central Venous Stenosis in Hemodialysis Patients: Long-Term Outcomes
The purpose of this study was to evaluate the long-term outcomes of endovascular treatment of central venous stenosis in patients with arteriovenous fistulas (AVFs) for hemodialysis. Five hundred sixty-three patients with AVFs who were referred for a fistulogram were enrolled in this study. Among them, 44 patients showed stenosis ( n  = 35) or occlusions ( n  = 9) in the central vein. For the initial treatment, 26 patients underwent percutaneous transluminal angioplasty (PTA) and 15 patients underwent stent placements. Periods between AVF formation and first intervention ranged from 3 to 144 months. Each patient was followed for 14 to 60 months. Procedures were successful in 41 of 44 patients (93.2%). Primary patency rates for PTA at 12 and 36 months were 52.1% and 20.0%, and assisted primary patency rates were 77.8% and 33.3%, respectively. Primary patency rates for stent at 12 and 36 months were 46.7% and 6.7%, and assisted primary patency rates were 60.0% and 20.0%, respectively. Fifteen of 26 patients with PTAs underwent repeated interventions because of restenosis. Fourteen of 15 patients with a stent underwent repeated interventions because of restenosis and combined migration ( n  = 1) and shortening ( n  = 6) of the first stent. There was no significant difference in patency between PTAs and stent placement ( p  > 0.05). Average AVF patency duration was 61.8 months and average number of endovascular treatments was 2.12. In conclusion, endovascular treatments of central venous stenosis could lengthen the available period of AVFs. There was no significant difference in patency between PTAs and stent placement.
Tumor necrosis in magnetic resonance imaging predicts urothelial carcinoma with squamous differentiation in muscle-invasive bladder carcinoma
PurposeThis study investigated radiologic features on preoperative MRI to differentiate urothelial carcinoma with squamous differentiation (UCSD) from conventional urothelial carcinoma (UC) in muscle-invasive bladder carcinoma.MethodsNinety-nine patients who underwent radical cystectomy and a preoperative bladder MRI scan within three months before surgery were retrospectively enrolled. Various MRI features, including tumor length, location, multiplicity, long-to-short axis ratio, morphology, radiologic stage, and degree of severe necrosis, were analyzed. Univariable and multivariable logistic regression analyses were performed to identify MRI features predictive of UCSD. The diagnostic performance of a significant MRI feature was assessed using 5-fold cross-validation.ResultsAmong the MRI features, significant radiologic findings associated with UCSD in the univariable analysis included heterogeneous tumor signal intensity in T2-weighted images (odds ratio [OR], 3.365; 95% confidence interval [CI], 1.213–9.986; P = 0.022) and contrast-enhanced T1-weighted images (OR, 4.428; 95% CI, 1.519–12.730; P = 0.007), as well as marked (≥ 50%) severe necrosis (OR, 17.100; 95% CI, 4.699–73.563; P < 0.001). In the multivariable analysis, marked (≥ 50%) severe necrosis (odds ratio [OR], 13.755; 95% confidence interval [CI], 2.796–89.118; P = 0.004) was a significant predictor of UCSD. Marked (≥ 50%) severe necrosis showed a high specificity of 95.0% with a precision of 65.0% for diagnosing UCSD based on 5-fold cross-validation.ConclusionPreoperative bladder MRI revealing marked severe necrosis may be indicative of UCSD and can assist in distinguishing it from conventional UC.
Peripheral zone thickness in preoperative MRI is predictive of Trifecta achievement after Holmium laser enucleation of the prostate (HoLEP)
PurposeTo investigate various anatomical features of the prostate using preoperative MRI and patients’ clinical factors to identify predictors of successful Holmium:YAG laser enucleation of the prostate (HoLEP).Methods71 patients who had received HoLEP and undergone a 3.0-T prostate MRI scan within 6 months before surgery were retrospectively enrolled. MRI features (e.g., total prostate and transitional zone volume, peripheral zone thickness [PZT], BPH patterns, prostatic urethral angle, intravesical prostatic protrusion, etc.) and clinical data (e.g., age, body mass index, surgical technique, etc.) were analyzed using univariable and multivariable logistic regression to identify predictors of successful HoLEP. Successful HoLEP was defined as achieving the Trifecta, characterized by the contemporary absence of postoperative complications within 3 months, a 3-month postoperative maximum flow rate (Qmax) > 15 mL/s, and no urinary incontinence at 3 months postoperatively.ResultsTrifecta achievement at 3 months post-surgery was observed in 37 (52%) patients. Patients with Trifecta achievement exhibited a lower preoperative IPSS-quality of life score (QoL) (4.1 vs. 4.5, P = 0.016) and a thinner preoperative peripheral zone thickness (PZT) on MRI (7.9 vs.10.3 mm, P < 0.001). In the multivariable regression analysis, a preoperative IPSS-QoL score < 5 (OR 3.98; 95% CI, 1.21–13.07; P = 0.017) and PZT < 9 mm (OR 11.51; 95% CI, 3.51–37.74; P < 0.001) were significant predictors of Trifecta achievement after HoLEP.ConclusionsAlongside the preoperative QoL score, PZT measurement in prostate MRI can serve as an objective predictor of successful HoLEP. Our results underscore an additional utility of prostate MRI beyond its role in excluding concurrent prostate cancer.
Postoperative results of ventilation tube insertion: a retrospective multicenter study for suggestion of grading system of otitis media with effusion
Background In otitis media with effusion (OME), it is important to know when to surgically intervene and when careful monitoring is more appropriate. This study aimed to visualize and classify the clinical manifestations of OME and the correlation between the new grading system and postoperative results after ventilation tube insertion (VTI). Methods We classified the collective 1,012 ears from 506 patients into six groups: grade 0 (no effusion), grade I (scant effusion, but abnormal), grade II (effusion less than half of the tympanic cavity), grade III (effusion over half of the tympanic cavity, with air bubbles), grade IV (complete effusion), and grade V (retracted tympanic membrane or hemotympanum without air bubbles). Results The mean age at VTI was 5.2 (±2.9) years and mean duration between diagnosis and operation was 4.1 (±1.8) months. Between the grades, the nature of the middle ear effusion was also significantly different ( p  < 0.001). The duration of ventilation tube retention after VTI was significantly different when compared between two groups: grade I-IV and grade V ( p  = 0.019). Our results showed that the recurrence rate, as well as rate of revision VTI, increased as the grade increased ( p  < 0.001). Conclusions The new grading system of OME using endoscopic otoscope evaluation had a significant correlation with the age at VTI, the nature of middle ear effusion, the recurrence rate of OME, and the rate of revision VTI.
Fluoroscopic subtraction Eustachian tubography: initial feasibility test in a cadaver model
ObjectivesTo evaluate the technical feasibility of direct Eustachian tube catheterisation and subtraction Eustachian tubography in a cadaver model.MethodsA total of 12 separate sessions were performed on both sides of the Eustachian tube (ET) in six human cadavers. Cadavers were positioned for the submentovertical view on a fluoroscopy table. Endoscopy-guided ET selection was used in the first three cadavers, whereas fluoroscopy-guided ET selection was used in the remaining three. Eustachian tubography was performed by injecting 2 ml of contrast media through a 5-Fr catheter. We recorded the success of ET selection, number of attempts, procedure time, and tubography quality using native and subtraction images (range, 0–3).ResultsBoth endoscopy- and fluoroscopy-guided selections were successfully performed in five of six sessions (83.3%). There were no statistically significant differences between the endoscopy- and fluoroscopy-guided procedures in terms of the number of attempts, procedure time, rate of immediate contrast leak to the middle ear cavity, and quality of tubography (p > 0.05). An excellent quality of tubography was obtained in 83.3% (10 of 12 sessions) of subtraction images and in 33.3% (4 of 12 sessions) of native images. The tubography quality score was significantly higher for the subtraction images than for the native images (p = 0.04).ConclusionSubtraction Eustachian tubography using direct catheterisation seems to be technically feasible. The entire ET can be well visualised; thus, this technique can be used as a simple tool for assessment of ET function and anatomy.Key Points• Direct catheterisation of the Eustachian tube is technically feasible.• The entire Eustachian tube could be well visualised by direct Eustachian tubography.• Subtraction Eustachian tubography images have better image quality than native images.• Subtraction Eustachian tubography can provide objective assessment of ET function and anatomy.
EPHA3 Contributes to Epigenetic Suppression of PTEN in Radioresistant Head and Neck Cancer
EPHA3, a member of the EPH family, is overexpressed in various cancers. We demonstrated previously that EPHA3 is associated with radiation resistance in head and neck cancer via the PTEN/Akt/EMT pathway; the inhibition of EPHA3 significantly enhances the efficacy of radiotherapy in vitro and in vivo. In this study, we investigated the mechanisms of PTEN regulation through EPHA3-related signaling. Increased DNA methyltransferase 1 (DNMT1) and enhancer of zeste homolog 2 (EZH2) levels, along with increased histone H3 lysine 27 trimethylation (H3K27me3) levels, correlated with decreased levels of PTEN in radioresistant head and neck cancer cells. Furthermore, PTEN is regulated in two ways: DNMT1-mediated DNA methylation, and EZH2-mediated histone methylation through EPHA3/C-myc signaling. Our results suggest that EPHA3 could display a novel regulatory mechanism for the epigenetic regulation of PTEN in radioresistant head and neck cancer cells.
Usefulness of Computed Tomography in the Etiologic Evaluation of Adult Unilateral Vocal Fold Paralysis
Background Unilateral vocal fold paralysis (UVFP) may present as an uncommon complication of extralaryngeal neoplasms, requiring diagnostic scrutiny to seek occult tumors or diseases. The aim of this study was to examine the utility of computed tomography (CT) in evaluating adult UVFP of unknown etiology. Methods From January 2010 to December 2011, UVFP was diagnosed in 822 patients at our tertiary-care center. In 634 patients, a readily identifiable cause of the UVFP was evident and therefore there was no need for any imaging; in the remaining 188 patients, the etiology could not be determined. Among this latter group, 153 patients underwent chest radiography (CXR) and contrast-enhanced CT imaging from the skull base to the midchest. Results In 36 of the 153 (23.5 %) patients, CT revealed the cause of the UVFP: lung cancer in 12 patients, thyroid carcinoma in 7 patients, skull-base tumor in 4 patients, aortic aneurysm in 4 patients, esophageal cancer in 3 patients, thymus tumor in 2 patients, pericardial effusion in 1 patient, and other neck lesions in 3 patients. CXR and neck ultrasonography also identified the etiology in 14 and 12 patients, respectively. During follow-up after the initial CT, none of the patients with idiopathic UVFP was determined to have an underlying disease that would have explained the paralysis. Conclusion CT is a useful single-imaging method for evaluating the etiology of adult UVFP. This approach may reveal occult tumors or previously undiagnosed diseases as the cause of the paralysis, thus improving patient care.
Treatment outcomes and prognostic factors in external auditory canal squamous cell carcinoma
External auditory canal carcinoma (EACC) is a rare and aggressive malignancy with substantial variability in prognosis depending on tumor stage and adjacent structure involvement. We retrospectively reviewed 56 patients with histologically confirmed squamous cell carcinoma of the external auditory canal treated at a tertiary referral center between 2000 and 2022. Clinical data including demographics, tumor stage, treatment modalities, surgical approach, and survival outcomes were analyzed. Kaplan–Meier survival curves and Cox proportional hazards regression were used to identify prognostic factors for overall survival (OS) and disease-specific survival (DSS). Of the 56 patients (mean age 61.6 years; 46.4% female), 30 had early-stage (T1–T2) and 26 had advanced-stage (T3–T4) tumors. The 5-year OS rates were 100.0% for early-stage, 60.0% for T3, and 42.0% for T4 disease. Advanced T-stage, nodal metastasis, and abutment to vascular structures such as the carotid artery or jugular bulb were significantly associated with worse outcomes. In multivariate analysis, younger age, vascular abutment, and nodal metastasis were independent negative prognostic factors. En bloc resection with clear margins was associated with improved survival. These findings emphasize the importance of early diagnosis and meticulous surgical planning to achieve complete resection and optimize outcomes in patients with EACC.