Objectives: . The recent expansion of eligibility for cochlear implantation (CI) by the U.S. Food and Drug Administration (FDA) to include infants as young as 9 months has reignited debates concerning the clinically appropriate cut-off age for pediatric CI. Our study compared the early postoperative trajectories of receptive and expressive language development in children who received CI before 9 months of age with those who received it between 9 and 12 months. This study involved a unique pediatric cohort with documented etiology, where the timing of CI was based on objective criteria and efforts were made to minimize the influence of parental socioeconomic status. Methods: . A retrospective review of 98 pediatric implantees recruited at a tertiary referral center was conducted. The timing of CI was based on auditory and language criteria focused on the extent of delay corresponding to the bottom 1st percentile of language development among age-matched controls, with patients categorized into very early (CI at <9 months), early (CI at 9–12 months) and delayed (CI at 12–18 months) CI groups. Postoperative receptive/expressive language development was assessed using the Sequenced Language Scale for Infants receptive and expressive standardized scores and percentiles. Results: . Only the very early CI group showed significant improvements in receptive language starting at 3 months post-CI, aligning with normal-hearing peers by 9 months and maintaining this level until age 2 years. During this period (<2 years), all improvements were more pronounced in receptive language than in expressive language. Conclusion . CI before 9 months of age significantly improved receptive language development compared to later CI, with improvements sustained at least up to the age of 2. This study supports the consideration of earlier CI, beyond pediatric Food and Drug Administration labeling criteria (>9 months), in children with profound deafness who have a clear deafness etiology and language development delays (<1st percentile).

Background/Aims: Synchronous multiple gastric cancer (SMGC) accounts for approximately 6% to 14% of gastric cancer (GC) cases. This study aimed to identify risk factors for SMGC. Methods: A total of 14,603 patients diagnosed with GC were prospectively enrolled. Data including age, sex, body mass index, smoking, alcohol consumption, family history, p53 expression, microsatellite instability, cancer classification, lymph node metastasis, and treatment were collected. Risk factors were analyzed using logistic regression analysis between a single GC and SMGC. Results: The incidence of SMGC was 4.04%, and that of early GC (EGC) and advanced GC (AGC) was 5.43% and 3.11%, respectively. Patients with SMGC were older (65.33 years vs 61.75 years, p<0.001) and more likely to be male. Lymph node metastasis was found in 27% of patients with SMGC and 32% of patients with single GC. Multivariate analysis showed that SMGC was associated with sex (male odds ratio [OR], 1.669; 95% confidence interval [CI], 1.223 to 2.278; p=0.001), age (≥65 years OR, 1.532; 95% CI, 1.169 to 2.008; p=0.002), and EGC (OR, 1.929; 95% CI, 1.432 to 2.600; p<0.001). Survival rates were affected by Lauren classification, sex, tumor size, cancer type, distant metastasis, and venous invasion but were not related to the number of GCs. However, the survival rate of AGC with SMGC was very high. Conclusions SMGC had unique characteristics such as male sex, older age, and EGC, and the survival rate of AGC, in which the intestinal type was much more frequent, was very good (Trial registration number: NCT04973631).

Thyroid nodules represent a prevalent condition that is detectable via palpation or ultrasound. In recent years, there has been a paradigm shift toward enhanced diagnostic precision and less aggressive therapeutic approaches, highlighting the growing necessity for tailored clinical recommendations to optimize patient outcomes. The Korean Thyroid Association (KTA) has developed guidelines for managing patients with thyroid nodules, following a comprehensive review by task force members of the relevant literature identified via electronic database searches. The recommendations are provided with a level of recommendation for each section. The guidelines encompass thyroid cancer screening in high-risk groups, appropriate diagnostic methods for thyroid nodules, role of pathologic and molecular marker testing in making a diagnosis, long-term follow-up and treatment of benign thyroid nodules, and special considerations for pregnant women. The major revisions that were made in the 2023 guidelines were the definition of high-risk groups for thyroid cancer screening, application of the revised Korean Thyroid Imaging Reporting and Data System (K-TIRADS), addition of the role of core needle biopsy and molecular marker tests, application of active surveillance in patients with low-risk papillary thyroid microcarcinoma, and updated indications for nonsurgical treatment of benign thyroid nodules. In the 2024 revision of the KTA guidelines for thyroid cancer, the evidence for some recommendations has been updated to address the tumor size in the context of active surveillance in patients with low-risk thyroid cancer and the surgical size cutoff. These evidence-based recommendations serve to inform clinical decision-making in the management of thyroid nodules, thereby facilitating the delivery of optimal and efficacious treatments to patients.

Differentiated thyroid cancer demonstrates a wide range of clinical presentations, from very indolent cases to those with an aggressive prognosis. Therefore, diagnosing and treating each cancer appropriately based on its risk status is important. The Korean Thyroid Association (KTA) has provided and amended the clinical guidelines for thyroid cancer management since 2007. The main changes in this revised 2024 guideline include 1) individualization of surgical extent according to pathological tests and clinical findings, 2) application of active surveillance in low-risk papillary thyroid microcarcinoma, 3) indications for minimally invasive surgery, 4) adoption of World Health Organization pathological diagnostic criteria and definition of terminology in Korean, 5) update on literature evidence of recurrence risk for initial risk stratification, 6) addition of the role of molecular testing, 7) addition of definition of initial risk stratification and targeting thyroid stimulating hormone (TSH) concentrations according to ongoing risk stratification (ORS), 8) addition of treatment of perioperative hypoparathyroidism, 9) update on systemic chemotherapy, and 10) addition of treatment for pediatric patients with thyroid cancer.

BACKGROUND: Currently, there is no apparent treatment for sarcopenia, which is characterized by diminished myoblast function. We aimed to manufacture exosomes that retain the myogenic differentiation capacity of human fetal cartilagederived progenitor cells (hFCPCs) and investigate their muscle regenerative efficacy in myoblasts and a sarcopenia rat model. METHODS: The muscle regeneration potential of exosomes (F-Exo) secreted during myogenic differentiation of hFCPCs was compared to human bone marrow mesenchymal stem cells-derived (hBMSCs) exosomes (B-Exo) in myoblasts and sarcopenia rat model. The effect of F-Exo was analyzed through known microRNAs (miRNAs) analysis. The mechanism of action of F-Exo was confirmed by measuring the expression of proteins involved in the Wnt signaling pathway. RESULTS: F-Exo and B-Exo showed similar exosome characteristics. However, F-Exo induced the expression of muscle markers (MyoD, MyoG, and MyHC) and myotube formation in myoblasts more effectively than B-Exo. Moreover, F-Exo induced greater increases in muscle fiber cross-sectional area and muscle mass compared to B-Exo in a sarcopenia rat. The miR-145-5p, relevant to muscle regeneration, was found in high concentrations in the F-Exo, and RNase pretreatment reduced the efficacy of exosomes. The effects of F-Exo on the expression of myogenic markers in myoblasts were paralleled by the miR-145-5p mimics, while the inhibitor partially negated this effect. F-Exo was involved in the Wnt signaling pathway by enhancing the expression of Wnt5a and b-catenin. CONCLUSION F-Exo improved muscle regeneration by activating the Wnt signaling pathway via abundant miR-145-5p, mimicking the remarkable myogenic differentiation potential of hFCPCs.

Background/Aims: There are few reports regarding mixed carcinoma, defined as a mixture of glandular and poorly cohesive components, in patients with gastric cancer (GC). The aim of this study was to evaluate the proportion and characteristics of mixed carcinoma in GC patients. Methods: A total of 7,215 patients diagnosed with GC at Seoul National University Bundang Hospital were enrolled from March 2011 to February 2020. GC was divided into four groups (wellmoderately differentiated GC, poorly differentiated GC, poorly cohesive carcinoma, and mixed carcinoma). The proportion of each GC type and the clinicopathological features were analyzed and divided into early GC and advanced GC. Results: The proportion of mixed carcinoma was 10.9% (n=787). In early GC, submucosal invasion was the most common in poorly differentiated (53.7%), and mixed carcinoma ranked second (41.1%). Mixed carcinoma showed the highest proportion of lymph node metastasis in early GC (23.0%) and advanced GC (78.3%). In advanced GC, the rate of distant metastasis was 3.6% and 3.9% in well-moderately differentiated GC and mixed carcinoma, respectively, lower than that in poorly differentiated GC (6.4%) and poorly cohesive carcinoma (5.7%), without statistical significance. Conclusions Mixed carcinoma was associated with lymph node metastasis compared to other histological GC subtypes. And it showed relatively common submucosal invasion in early GC, but the rates of venous invasion and distant metastasis were lower in advanced GC. Further research is needed to uncover the mechanism underlying these characteristics of mixed carcinoma (Trial registration number: NCT04973631).

Background: The Omicron variant has become the most prevalent SARS-CoV-2 variant. Omicron is known to induce milder lesions compared to the original Wuhan strain. Fatal infection of the Wuhan strain into the brain has been well documented in COVID-19 mouse models and human COVID-19 cases, but apparent infections into the brain by Omicron have not been reported in human adult cases or animal models. In this study, we investigated whether Omicron could spread to the brain using K18-hACE2 mice susceptible to SARS-CoV-2 infection. Results: K18-hACE2 mice were intranasally infected with 1 × 105 PFU of the original Wuhan strain and the Omicron variant of SARS-CoV-2. A follow-up was conducted 7 days post infection. All Wuhan-infected mice showed > 20% body weight loss, defined as the lethal condition, whereas two out of five Omicron-infected mice (40%) lost > 20% body weight. Histopathological analysis based on H&E staining revealed inflammatory responses in the brains of these two Omicron-infected mice. Immunostaining analysis of viral nucleocapsid protein revealed severe infection of neuron cells in the brains of these two Omicron-infected mice. Lymphoid depletion and apoptosis were observed in the spleen of Omicron-infected mice with brain infection. Conclusion Lethal conditions, such as severe body weight loss and encephalopathy, can occur in Omicron-infected K18-hACE2 mice. Our study reports, for the first time, that Omicron can induce brain infection with lymphoid depletion in the mouse COVID-19 model.

Thyroid nodules are a prevalent condition that can be detected through palpation or ultrasound. However, a small fraction of these nodules can be cancerous, and even benign nodules can cause symptoms if they grow and compress surrounding tissue. As such, it is important to monitor thyroid nodules and determine appropriate treatment options. In recent years, there has been a shift towards enhancing diagnostic accuracy and less aggressive treatment options. As a result, there is a growing need for the development of appropriate recommendations for their clinical application to ensure optimal patient outcomes. The present clinical practice guideline was developed by extracting the nodule section from the prior version of guidelines and updating it to fit the Korean circumstances. Task force members reviewed relevant studies selected after electronic database searching, and the recommendations are provided with a level of recommendation for each section. The revised guideline includes recommendations for thyroid cancer screening in high-risk groups, appropriate diagnostic methods for thyroid nodules, the role of pathological and molecular marker tests in diagnosis, long-term follow-up and treatment of benign thyroid nodules, and special considerations for pregnant women. The major changes in this revision are the definition of high-risk groups for thyroid cancer screening, the application of the revised Korean Thyroid Imaging Reporting and Data System (K-TIRADS), the addition of the role of core needle biopsy and molecular marker tests, the application of active surveillance in low-risk papillary thyroid microcarcinoma, and updated indications for non-surgical treatment of benign thyroid nodules. These evidence-based recommendations are expected to assist in clinical decision-making for thyroid nodule management, ensuring that patients receive the most appropriate and effective treatment options.

Purpose: The purpose of this study was to investigate the effectiveness of the elastic compression stockings and Kinesio taping on muscle activity and mechanical properties in healthy women during the heel raise exercise that causes muscle fatigue. Methods: Participants were divided into the elastic compression stockings group (ESG, n= 8), Kinesio taping group (KTG, n= 8), and control group (CG, n= 8). All participants performed the heel raise exercise to cause muscle fatigue. Muscle activity, stiffness, and the muscle tone of the gastrocnemius and tibialis anterior were measured before and after the heel raise exercise. Results: In the gastrocnemius, muscle activity was significantly increased after the heel raise exercise in both the ESG and KTG (p< 0.05).There was a significant difference in the change in the gastrocnemius muscle activity between the groups (p< 0.05). Post hoc analysis showed that the ESG exhibited a significantly greater change in gastrocnemius muscle activity than the CG (p< 0.05). The muscle stiffness of the gastrocnemius was significantly decreased after the heel raise exercise in the ESG (p< 0.05). The muscle tone of the gastrocnemius was significantly increased after the heel raise exercise in the control group (p< 0.05). There were no significant differences in the change in the gastrocnemius stiffness and muscle tone between the groups (p> 0.05). In the tibialis anterior, there were no significant differences in muscle activity, stiffness, and muscle tone between and within the groups (p> 0.05). Conclusion Our findings suggest that the use of elastic compression stockings and Kinesio taping during the heel raise exercise are beneficial and delay muscle fatigue in the gastrocnemius.

Background/Aims: Although a management fee for hospitalist service was established in Korea, the number of hospitalists required for the system to run remains outmatched. Methods: In January 2020 and February 2022, before and after the establishment of the hospitalist fee system respectively, cross-sectional online surveys were conducted among internal medicine board-certified hospitalists. Results: There were 59 and 64 respondents in the 2020 and 2022 surveys, respectively. The percentage of respondents who cited financial benefits as a motive for becoming a hospitalist was higher in the 2022 survey than in the 2020 survey (34.4% vs. 10.2%; p = 0.001). The annual salary of respondents was also higher in the 2022 survey than in the 2020 survey (mean, 182.9 vs. 163.0 million in South Korean Won; p = 0.006). A total of 81.3% of the respondents were willing to continue a hospitalist career in the 2022 survey. In multivariate regression analysis, the possibility of being appointed as a professor was found to be an independent predictive factor of continuing a hospitalist career (odds ratio, 4.00; 95% confidence interval, 1.09–14.75; p = 0.037). Conclusions Since the establishment of the hospitalist fee system, monetary compensation has improved for hospitalists. The possibility of being appointed as a professor could predict long-term work as hospitalists.