1.Acute Heart Failure Across the Ejection Fraction Spectrum: Phenotypes, Management, and Outcomes From Nationwide KorHF III Registry
Huijin LEE ; Eung Ju KIM ; Seong Woo HAN ; Seong-Mi PARK ; Hyung-Seop KIM ; Myung-Chan CHO ; Hyo-Suk AHN ; Mi-Seung SHIN ; Seok-Jae HWANG ; Jin-Ok JEONG ; Dong Heon YANG ; Junho HYUN ; Jin Oh CHOI ; Hae-Young LEE ; Byung-Su YOO ; Seok-Min KANG ; Dong-Ju CHOI ; Hyun-Jai CHO ;
International Journal of Heart Failure 2026;8(1):43-55
Background and Objectives:
Clinical characteristics and outcomes in acute heart failure (AHF) vary by phenotype. We assessed phenotype-specific features, treatment patterns, and outcomes in a nationwide Korean cohort.
Methods:
The Korean Heart Failure III registry prospectively enrolled 7,351 AHF admissions at 47 hospitals. Among 6,777 patients with available left ventricular ejection fraction (EF), phenotypes were defined as heart failure with reduced EF (HFrEF, ≤40%), mildly reduced EF (HFmrEF,41–49%), or preserved EF (HFpEF, ≥50%). The primary endpoint was a 12-month composite of all-cause death or heart transplantation, evaluated from index admission and, among hospital survivors, from discharge. We used inverse probability weighting (multinomial generalized boosted models with stabilized, trimmed weights) and weighted Cox proportional-hazards models to estimate hazard ratios (HRs).
Results:
Phenotype distribution was 58.9% HFrEF, 13.6% HFmrEF, and 27.5% HFpEF. Crude 12-month composite rates from index admission were 13.4% (HFrEF), 12.7% (HFmrEF), and 16.8% (HFpEF). After weighting, from index admission, HFmrEF (HR, 0.892; 95% confidence interval [CI], 0.731–1.088) and HFpEF (HR, 1.101; 95% CI, 0.939–1.291) did not differ from HFrEF; from discharge, HFpEF had modestly higher risk (HR, 1.207; 95% CI, 1.008–1.445) whereas HFmrEF did not (HR, 1.039; 95% CI, 0.844–1.279). Hyponatremia and chronic kidney disease were consistent adverse markers, while angiotensin-converting enzyme inhibitor/ angiotensin II receptor blocker use at discharge was protective.
Conclusions
Across the EF spectrum, phenotypes showed distinct profiles and risk. Postdischarge risk was modestly higher in HFpEF, supporting phenotype-tailored care and systematic discharge optimization in Korean patients with AHF.
2.Development of Korean Standardized Heart Failure Registry: Experience From Integration of KorAHF and KorHF III
Eui-Soon KIM ; Huijin LEE ; Jong-Chan YOUN ; Byung-Su YOO ; Hae-Young LEE ; Ju-Hee LEE ; Dong-Hyuk CHO ; Mi-Hyang JUNG ; Hye Sun LEE ; Hyun-Jai CHO
International Journal of Heart Failure 2026;8(1):1-11
Heart failure (HF) prevalence and associated socio-economic costs have risen rapidly in Korea, creating urgent demand for a national, standardized prospective registry to support quality monitoring, outcome comparison, and real-world evidence. Standardized data definitions are essential for valid comparisons across studies and healthcare settings. We created a unified national HF cohort by integrating the two largest Korean registries, KorAHF (2011–2014;n=5,625) and KorHF III (2018–2023; n=7,351), yielding 12,976 hospitalized HF patients. Because heterogeneous variable definitions impeded direct comparisons, we implemented a harmonization pipeline across demographic, clinical, imaging, biomarker, therapeutic, and outcome domains, aligned with international standards and reinforced by systematic data quality checks.A multidisciplinary panel then conducted a structured decision process to produce the Korean HF Standard Dataset, a tiered and interoperable variable set spanning six domains: demographics, presentation at admission, in-hospital events and comorbidities, discharge status, outpatient follow-up, and readmission events. This integrated platform and standardized variables enable precise identification of HF patient phenotypes and prognostic factors, establishing an evidence-based foundation for disease management. This supports an analysis of temporal changes in treatment patterns and outcomes, generates data to inform future clinical practice guidelines, and provides a practical basis for planning large, continuous, prospective HF registries. Furthermore, it also facilitates pragmatic, registry-based randomized clinical trials and unmet-needs assessments that can guide national health policy. Establishing a foundation for future linkage with national health databases, this platform will allow for enhanced accuracy, comparability, and representativeness, powering quality improvement initiatives and population-level monitoring of Korea’s growing HF burden.
3.Protective Effect of Brain Derived Neurotrophic Factor-Overexpressing Wharton’s Jelly-Derived Mesenchymal Stromal Cells in Severe Intraventricular Hemorrhage in Newborn Rats
So Yeon JUNG ; Misun YANG ; Young Eun KIM ; Dong Kyung SUNG ; Se In SUNG ; Chang-Woo LEE ; Yun Sil CHANG ; So Yoon AHN
International Journal of Stem Cells 2026;19(1):54-65
The brain-derived neurotrophic factor (BDNF) plays a crucial role in neuroprotection, and we have previously demonstrated BDNF-mediated neuroprotective effects in mesenchymal stromal cells (MSCs). The present study aimed to investigate whether BDNF-overexpressing MSCs enhance the therapeutic efficacy of naïve MSCs in a preclinical model of severe neonatal intraventricular hemorrhage (IVH). We exposed primary rat neuronal cells to 40 U of thrombin overnight in vitro. Subsequently, the neuronal cells were co-cultured with either naïve MSCs or BDNF-overexpressing MSCs (1×105 cells in 1 mL media) for 24 hours. Next, 300 μL of maternal blood was injected into bilateral ventricles on postnatal day (P)4 to induce severe IVH in newborn Sprague-Dawley male rats. At P6, either naïve MSCs or BDNF-overexpressing MSCs (1×105 cells in 10 μL saline) were transplanted intraventricularly. Behavioral function tests, including passive avoidance, followed by endpoint analyses of brain tissue and cerebrospinal fluid were performed at P35. BDNF-overexpressing MSCs enhanced the effects of naïve MSCs against cell death, cytotoxicity, and oxidative stress in vitro. Notably, naïve and BDNF-overexpressing MSCs did not attenuate post-hemorrhagic ventricular dilatation, neuronal cell death, or gliosis. However, BDNF-overexpressing MSCs attenuated microglial activation.Furthermore, inflammatory cytokine (interleukin [IL]-1α, IL-1β, IL-6, and tumor necrosis factor-α) levels and memory function assessed using a passive avoidance test significantly improved in the BDNF-overexpressing MSC transplanted group compared with the naïve MSC transplanted group. Our data suggest that BDNF-overexpressing MSCs may offer superior protective effects to naïve MSCs in a neonatal IVH model.
4.Extracellular Vesicles in Liver Disease: Redefining Diagnostic and Therapeutic Strategies
A-Reum KIM ; Minseok KANG ; Dong-Young KIM ; Kidus Haile YEMANEBERHAN ; Dongho CHOI
International Journal of Stem Cells 2026;19(1):20-40
Extracellular vesicles (EVs) are crucial mediators of intercellular communication, which facilitate the transfer of bioactive molecules such as proteins, lipids, and nucleic acids. Their high biocompatibility and intrinsic targeting abilities make them promising candidates for therapeutics, drug delivery, and disease biomarkers. In liver diseases, EVs are essential in liver regeneration, fibrosis modulation, and ischemia-reperfusion injury repair, and EV-derived biomarkers have shown potential for non-invasive disease monitoring, particularly in hepatitis B virus infection, non-alcoholic fatty liver disease, and hepatocellular carcinoma. This review provides a comprehensive overview of EV biology, cellular sources, isolation techniques, and strategies to enhance their therapeutic potential. Furthermore, we discuss the role of EVs in liver regeneration and their clinical application in biomarker discovery. Despite significant advancements in EV-based therapies, challenges such as scalability, standardization, immunogenicity, and regulatory approval remain key hurdles for clinical translation. Future research should focus on optimizing EV bioengineering, refining isolation methods, and addressing regulatory concerns to facilitate successful application of EVs in liver disease management and precision medicine.
5.Korean Thyroid Association Guidelines on the Management of Differentiated Thyroid Cancers; Part II. Follow-up Surveillance after Initial Treatment 2026
Eun Kyung LEE ; Seung Heon KANG ; Bon Seok KOO ; Mijin KIM ; Min Joo KIM ; Bo Hyun KIM ; Ji Won KIM ; Dong Gyu NA ; Sohyun PARK ; Ji-In BANG ; Kyorim BACK ; Youngduk SEO ; Young-Ik SON ; Young Shin SONG ; Dong Yeob SHIN ; Jong-Hyuk AHN ; Hwa Young AHN ; So Won OH ; Ho-Ryun WON ; Won Sang YOO ; Min Kyoung LEE ; Sang-Woo LEE ; Jeongmin LEE ; Ji Ye LEE ; Dong-Jun LIM ; Ki-Wook CHUNG ; Ari CHONG ; Jin Hyang JUNG ; Sun Wook CHO ; Yoon Young CHO ; Chae Moon HONG ; Young Joo PARK ;
International Journal of Thyroidology 2026;19(1):1-40
In patients with differentiated thyroid cancer (DTC), initial recurrence risk stratification based on clinical, histopathological, and perioperative data remains the key determinant for guiding management strategies during the first 1-2 years post-treatment. However, the adoption of ongoing risk stratification (ORS), which dynamically reassesses risk by integrating longitudinal clinical data and treatment response, enables more precise long-term prognostic assessment and facilitates highly individualized management. Building upon recent guidelines, the 2026 KTA guideline has been further refined by incorporating robust evidence from large-scale national cohorts and comprehensive systematic reviews. These updated recommendations outline contemporary concepts of ORS, risk-adapted TSH suppression targets, optimized surveillance modalities for recurrence detection, and disease-specific long-term follow-up strategies. Reflecting the paradigm shift toward de-escalated treatment, this revision integrates evolved perspectives on TSH suppression intensity, the clinical interpretation of thyroglobulin levels, and tailored follow-up intervals. These evidence-based recommendations aim to minimize unnecessary treatment and excessive surveillance in the large proportion of patients with excellent prognosis after initial therapy, while ensuring that each patient receives appropriately tailored and effective long-term management.
6.Assessment of Fat Fraction and Muscle Atrophy in the Supraspinatus Muscle:Optimal Sagittal Plane Selection in the Shoulder MRI
Chanyoung RHEE ; Hye Jin YOO ; Tae Kun KIM ; Hee Dong CHAE ; Ja-Young CHOI ; Sung Hwan HONG
Investigative Magnetic Resonance Imaging 2026;30(1):29-37
Purpose:
To assess the accuracy of supraspinatus muscle fat fraction and atrophy measured on the Y-view compared with the newly proposed fossa-view sagittal MRI plane.
Materials and Methods:
This study included 84 patients (36 male; mean age, 65.1 ± 10.1 years) who underwent shoulder MRI with extended oblique sagittal T1-weighted and three-dimensional (3D) six-echo Dixon imaging between December 2020 and November 2022. The reference fat fraction was calculated by integrating voxel-wise Dixon values, while supraspinatus muscle volume was quantified using a 3D nnU-Net algorithm and normalized to the scapular volume to derive the standardized muscle index (SMI). Fat fraction and cross-sectional area were quantified on the Y-view and fossaview and compared with the reference values. Subgroup analyses were performed using fatty degeneration and retraction grades.
Results:
Agreement with the reference fat fraction was significantly higher for the fossa-view (intraclass correlation coefficient [ICC], 0.923) than for the Y-view (ICC, 0.822;p = 0.006). The fossa-view showed smaller deviations and narrower limits of agreement.For SMI, the Y-view (ICC, 0.782) showed higher agreement than the fossa-view (ICC, 0.694), although the difference was not statistically significant (p = 0.219). Subgroup analyses showed better Y-view performance at lower retraction grades and better fossa-view performance at higher grades, although the differences were not statistically significant (all p > 0.05).
Conclusion
Both planes reliably quantified the fat fraction with greater accuracy in the fossa-view. However, single-plane assessment of muscle atrophy was less reliable, underscoring the need for MRI evaluation of the entire muscle.
7.Impact of a Shift Work Improvement System on Nurses' Work-Life Balance, Turnover Intention, and Teamwork
Journal of Korean Clinical Nursing Research 2026;32(1):45-53
Purpose:
This study aimed to compare work-life balance, turnover intention, and teamwork between nurses in wards participating in a shift work improvement pilot program and those in non-participating wards.
Methods:
In this comparative descriptive study, 201 nurses working at D University hospital located in B city, including 71 participants in the pilot program and 130 non-participants. Data were collected from August 1 to August 31, 2025, using a structured questionnaire. The collected data were analyzed using IBM SPSS Statistics 29.0 including descriptive statistics, t-tests, χ2 tests, and one-way ANOVA.
Results:
The results of this study indicated that participation in the shift improvement pilot program significantly enhanced nurses' work-life balance (t=2.03, p=.044), particularly in the work-leisure (t=2.42, p=.016) and work-growth (t=2.00, p=.047), whereas no significant differences were found in turnover intention or teamwork between the groups. Regarding individual characteristics, work-life balance was significantly higher among unmarried and male nurses (t=2.23, p=.029). Turnover intention was notably higher among those with a bachelor’s degree or lower (t=2.56, p=.012) and those with 3 to 5 years of experience in their current department (F=4.63, p=.012). Teamwork was reported at higher levels by nurses with less than 3 years of experience (F=3.45, p=.035).
Conclusion
Participation in the shift work improvement pilot program was associated with higher work-life balance, particularly in relation to leisure and professional growth. However, participation was not associated with differences in turnover intention or teamwork, suggesting that these outcomes may be influenced by factors beyond shift work arrangements.
8.Eyeball Donation and Management System
Jaeyoung KIM ; Chul Young CHOI ; Jae Yong KIM ; Roo Min JUN ; Eun Chul KIM ; Yong-Soo BYUN ; Jong Hwa JUN ; Dong Hyun KIM ; Yunjin LEE ; Hyung Keun LEE ; Mee Kum KIM
Journal of the Korean Ophthalmological Society 2026;67(2):33-46
Purpose:
To propose improvements for promoting eyeball donation and managing donated corneas, this study analyzed the current system in Korea and reviewed relevant Korean laws, international standards, and foreign practices.
Methods:
To understand the current situation in Korea, annual reports published by the Korean Network for Organ Sharing and existing Korean laws were examined. For the international context, references were made to the National Organ Transplant Act, 21 CFR Part 1271 (Code of Federal Regulations Title 21 Part 1271), Current Good Tissue Practice guidelines of the Food and Drug Administration, and the Medical Standards of the Eye Bank Association of America in the United States. Opinions on promoting eyeball donation, improving the monitoring system for donated corneas and revising laws related to cornea management were gathered. The perspectives of 31 experts affiliated with the Korea Cornea Society were collected through a survey.
Results:
Currently, there are no laws or regulations that can be appropriately applied to the cornea which has properties of both organs and tissue. Additionally, there is no law regulating imported corneas. Therefore, there is a need to legislate or revise the current law; all experts who conducted the survey agreed on this. Furthermore, the current system faces limitations in the efficient procurement, stable supply, and management of donor corneas, as well as in donation promotion. To address these issues, the establishment of independent legislation for managing donated corneas and a National Central Eye Bank was proposed. This central body would oversee continuous personnel training, education, and monitoring, along with ensuring stable procurement, processing, and supply of corneas within a structured management system. Sixty-eight percent of the surveyed experts agreed with this proposal.
Conclusions
To establish a safe and efficient Korean corneal supply and demand system, it is imperative to enact cornea-specific laws, including the establishment of a National Central Eye Bank.
9.A multi-city outbreak of Salmonella Enteritidis infections linked to bakery products, Republic of Korea
Da Seul KIM ; Soon-Young SEO ; Dong Hwi KIM ; Yeon Hee WOO ; Deborah LEE ; Se Jeong YANG ; Junyoung KIM ; Eunkyung SHIN ; Byungsun JUNG ; Eunmi LEE ; Min Jung LEE ; Young-Joon PARK
Osong Public Health and Research Perspectives 2026;17(1):61-71
Objectives:
In May 2025, clusters of salmonellosis were identified in 7 cities in the Republic of Korea, all associated with consumption of identical bakery products. This investigation aimed to characterize the outbreak, identify potential contributing factors, and inform strategies for preventing similar multi-facility foodborne outbreaks.
Methods:
A case series study was conducted among individuals who consumed Manufacturer H’s Product I and Product II on May 15–16, 2025 at 7 facilities (n = 1,235). Clinical specimens from symptomatic individuals, retained food samples, and environmental samples were collected and tested. Food-exposure histories were assessed, and active case finding was implemented across all supplied facilities. Traceback investigations were conducted at the manufacturer, distributor, and egg farms. Human and food isolates underwent pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS).
Results:
A total of 323 cases met the outbreak case definition (attack rate, 26.2%), of which 48 were laboratory-confirmed. Salmonella Enteritidis was isolated from both clinical specimens and retained bakery products. PFGE patterns were indistinguishable between human and food isolates, and WGS demonstrated high genetic relatedness. These findings confirmed a common-source outbreak linked to the implicated bakery products.
Conclusion
This outbreak underscores the value of integrating epidemiological investigation, active case finding, and molecular typing to identify common food vehicles in outbreaks involving widely distributed manufactured foods. Coordinated collaboration between public health and food safety authorities is essential for the effective detection, response, and prevention of multi-facility foodborne outbreaks.
10.Incidental White Matter Lesions in Pediatric Headache: Prevalence and Longitudinal Magnetic Resonance Imaging Findings
Young Hwan KIM ; Dong Won LEE ; Kye Hyang LEE
Annals of Child Neurology 2026;34(2):144-150
Purpose:
Brain magnetic resonance imaging (MRI) is commonly performed to exclude secondary causes of pediatric headache. Incidental findings are detected in approximately one-fifth of scans, and nonspecific white matter lesions (WMLs) have been reported in 0.7% to 47% of pediatric patients with headache. However, the natural history of these lesions remains unclear. This study aimed to determine the prevalence and radiologic course of WMLs in pediatric patients with headache.
Methods:
We retrospectively reviewed the clinical and MRI data of pediatric patients who underwent brain MRI for headache at a single tertiary-care center between September 2006 and July 2023. Patients with neurological or systemic conditions known to cause WMLs were excluded. MRI findings and clinical characteristics were analyzed descriptively.
Results:
Among the 515 enrolled patients (mean age, 10.7 years), abnormal MRI findings were observed in 126 (24.5%), including nonspecific WMLs in eight (1.6%). Most lesions were supratentorial (seven of eight), with a mean maximum diameter of 10.0 mm (range, 4.3 to 24.9). Follow-up MRI was available for three patients; two demonstrated interval increases in lesion extent on repeat imaging. During the same period, headache frequency or severity also increased, but no new neurological deficits were documented.
Conclusion
Nonspecific WMLs were rare in pediatric patients with headache. In a small subset with limited follow-up, interval radiologic changes were observed without neurological deterioration. Larger prospective studies are needed to clarify the natural history and clinical significance of WMLs in pediatric headache.

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