1.Establishing a Cre/loxP-based genetic manipulation system for Acanthamoeba: Targeted genome editing and stable reporter expression
Ja Moon AUNG ; So-Young JOO ; Byoung-Kuk NA ; Seunghyeok BANG ; Minsang SHIN ; Youn-Kyoung GOO ; Yeonchul HONG
Parasites, Hosts and Diseases 2025;63(1):25-36
Acanthamoeba is an opportunistic pathogen responsible for granulomatous amoebic encephalitis and amoebic keratitis. Despite its clinical significance, effective treatments remain challenging due to a limited understanding of its pathogenic mechanism. This study developed a genetic manipulation system in Acanthamoeba to facilitate gene function and drug screening studies. We applied the Cre/loxP system to integrate the gene encoding the tdTomato fluorescent protein into the genome of Acanthamoeba castellanii via homologous recombination. The polyubiquitin gene and its untranslated regions were identified and verified, after which the tdTomato gene was cloned between the untranslated regions of the polyubiquitin gene. The construct was then introduced into the Acanthamoeba genome using a modified pLPBLP vector containing loxP sites. Cre recombinase was utilized to remove the neomycin resistance cassette flanked by loxP sites, and genetically modified cells were selected by clonal dilution. The integration of the tdTomato gene, confirmed through PCR and fluorescence microscopy, showed stable expression in both trophozoites and cysts without the need for antibiotic selection. We demonstrated the feasibility of antibiotic-free reporter gene expression in Acanthamoeba. The system provides a valuable tool for functional genomics, allowing us to explore gene functions in Acanthamoeba and develop reliable drug screening models. Furthermore, the ability to express genes without the continuous use of selection markers opens up new possibilities for studying the pathobiology of this pathogen and advancing the development of novel therapeutic strategies against Acanthamoeba infections.
2.A New Agenda for Optimizing Roles and Infrastructure in a Mental Health Service Model for South Korea
Eunsoo KIM ; Hyeon-Ah LEE ; Yu-Ri LEE ; In Suk LEE ; Kyoung-Sae NA ; Seung-Hee AHN ; Chul-Hyun CHO ; Hwoyeon SEO ; Soo Bong JUNG ; Sung Joon CHO ; Hwa-Young LEE
Psychiatry Investigation 2025;22(1):26-39
Objective:
As the demand for community mental health services continues to grow, the need for well-equipped and organized services has become apparent. This study aimed to optimize the roles and infrastructure of mental health services, by establishing, among other initiatives, standardized operating models.
Methods:
The study was conducted in multiple phases from May 12, 2021, to December 29, 2021. Stakeholders within South Korea and metropolitan mental health welfare centers were targeted, but addiction management support centers, including officials, patients, and their families, were integrated as well. A literature review and survey, focus group interviews, a Delphi survey, and expert consultation contributed to comprehensive revisions and improvements of the mental health service model.
Results:
The proposed model for community mental health welfare centers emphasizes the expansion of personnel and infrastructure, with a focus on severe mental illnesses and suicide prevention. The model for metropolitan mental health welfare centers delineates essential tasks in areas such as project planning and establishment, community research, and education about severe mental illnesses. The establishment of a 24-hour emergency intervention center was a crucial feature. In the integrated addiction support center model, the need to promote addiction management is defined as an essential task and the establishment of national governance for addiction policies is recommended.
Conclusion
This study proposed standard operating models for three types of mental health service centers. To meet the increasing need for community care, robust mental health service delivery systems are of primary importance.
3.Therapeutic Approach to Epilepsy in Patients with Mitochondrial Diseases
Yonsei Medical Journal 2025;66(3):131-140
Mitochondrial diseases (MDs) are genetic disorders with diverse phenotypes that affect high-energy-demand organs, notably the central nervous system and muscles. Epilepsy is a common comorbidity, affecting 40%–60% of patients with MDs and significantly reducing their quality of life. This review discusses the different treatment modalities for epilepsy in patients with MDs. Advances in genetic sequencing have identified specific mutations in mitochondrial and nuclear DNA, enabling more precise diagnoses and tailored therapeutic strategies. Anti-seizure medications and dietary interventions, such as ketogenic diets and their variants, have been effective in reducing seizures and improving mitochondrial function. Emerging treatments include gene therapy, mitochondrial transplantation, and antioxidants such as EPI-743, which protect mitochondrial integrity and improve neurological function. Additionally, therapies that promote mitochondrial biogenesis, such as bezafibrate and epicatechin, are being explored for their potential to enhance mitochondrial proliferation and energy production. Gene therapy aims to correct genetic defects underlying MDs. Techniques like mitochondrial gene replacement and using viral vectors to deliver functional genes have shown promise in preclinical studies. Mitochondrial transplantation, an emerging experimental technique, involves transferring healthy mitochondria into cells with dysfunctional mitochondria. This technique has been demonstrated to restore mitochondrial function and energy metabolism in preclinical models. Patient-derived induced pluripotent stem cells can model specific mitochondrial dysfunctions in vitro, allowing for the testing of various treatments tailored to individual genetic and biochemical profiles. The future of mitochondrial medicine is promising, with the development of more targeted and personalized therapeutic strategies offering hope for improved management and prognosis of mitochondrial epilepsy.
4.Comparison of tissue-based and plasma-based testing for EGFR mutation in non–small cell lung cancer patients
Yoon Kyung KANG ; Dong Hoon SHIN ; Joon Young PARK ; Chung Su HWANG ; Hyun Jung LEE ; Jung Hee LEE ; Jee Yeon KIM ; JooYoung NA
Journal of Pathology and Translational Medicine 2025;59(1):60-67
Background:
Epidermal growth factor receptor (EGFR) gene mutation testing is crucial for the administration of tyrosine kinase inhibitors to treat non–small cell lung cancer. In addition to traditional tissue-based tests, liquid biopsies using plasma are increasingly utilized, particularly for detecting T790M mutations. This study compared tissue- and plasma-based EGFR testing methods.
Methods:
A total of 248 patients were tested for EGFR mutations using tissue and plasma samples from 2018 to 2023 at Pusan National University Yangsan Hospital. Tissue tests were performed using PANAmutyper, and plasma tests were performed using the Cobas EGFR Mutation Test v2.
Results:
All 248 patients underwent tissue-based EGFR testing, and 245 (98.8%) showed positive results. Of the 408 plasma tests, 237 (58.1%) were positive. For the T790M mutation, tissue biopsies were performed 87 times in 69 patients, and 30 positive cases (38.6%) were detected. Plasma testing for the T790M mutation was conducted 333 times in 207 patients, yielding 62 positive results (18.6%). Of these, 57 (27.5%) were confirmed to have the mutation via plasma testing. Combined tissue and plasma tests for the T790M mutation were positive in nine patients (13.4%), while 17 (25.4%) were positive in tissue only and 12 (17.9%) in plasma only. This mutation was not detected in 28 patients (43.3%).
Conclusions
Although the tissue- and plasma-based tests showed a sensitivity of 37.3% and 32.8%, respectively, combined testing increased the detection rate to 56.7%. Thus, neither test demonstrated superiority, rather, they were complementary.
5.The Effects of Nicotine on Re-endothelialization, Inflammation, and Neoatherosclerosis After Drug-Eluting Stent Implantation in a Porcine Model
Seok OH ; Ju Han KIM ; Saleem AHMAD ; Yu Jeong JIN ; Mi Hyang NA ; Munki KIM ; Jeong Ha KIM ; Dae Sung PARK ; Dae Young HYUN ; Kyung Hoon CHO ; Min Chul KIM ; Doo Sun SIM ; Young Joon HONG ; Seung-won LEE ; Youngkeun AHN ; Myung Ho JEONG
Korean Circulation Journal 2025;55(1):50-64
Background and Objectives:
Cigarette smoking is a major risk factor for atherosclerosis.Nicotine, a crucial constituent of tobacco, contributes to atherosclerosis development and progression. However, evidence of the association between nicotine and neointima formation is limited. We aimed to evaluate whether nicotine enhances neointimal hyperplasia in the native epicardial coronary arteries of pigs after percutaneous coronary intervention (PCI) with drug-eluting stents (DES).
Methods:
After coronary angiography (CAG) and quantitative coronary angiography (QCA), we implanted 20 DES into 20 pigs allocated to 2 groups: no-nicotine (n=10) and nicotine (n=10) groups. Post-PCI CAG and QCA were performed immediately. Follow-up CAG, QCA, optical coherence tomography (OCT), and histopathological analyses were performed 2 months post-PCI.
Results:
Despite intergroup similarities in the baseline QCA findings, OCT analysis showed that the nicotine group had a smaller mean stent and lumen areas, a larger mean neointimal area, greater percent area stenosis, and higher peri-strut fibrin and inflammation scores than the no-nicotine group. In immunofluorescence analysis, the nicotine group displayed higher expression of CD68 and α-smooth muscle actin but lower CD31 expression than the no-nicotine group.
Conclusions
Nicotine inhibited re-endothelialization and promoted inflammation and NIH after PCI with DES in a porcine model.
6.Fatal Pulmonary Embolism Due to Deep Vein Thrombosis after Severe Acute Respiratory Syndrome Coronavirus 2 Infection
Bokyung HA ; Joo-Young NA ; Min-Jung KIM
Korean Journal of Legal Medicine 2025;49(1):16-20
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection contribute to platelet activation and thrombus formation. Severe coronavirus disease 2019 (COVID-19) is characterized by an increased risk of thromboembolic events that can lead to adverse outcomes in patients with severe disease manifestations. We present the case of a 41-year-old man who died from a pulmonary embolism and review the connection between SARS-CoV-2 infection, increased platelet counts, and the resulting fatal thrombosis. Total knee replacement surgery was performed and the patient was able to ambulate for a few days postoperatively. The platelet count exceeded the upper limit between postoperative days six and nine, reaching 708,000/μL on day 20. SARS-CoV-2 was confirmed 14 days after surgery, and the patient died 23 days after surgery while hospitalized. Autopsy revealed a fatal pulmonary embolism and deep vein thrombosis. If blood clots are caused by increased platelet counts due to COVID-19, it is essential to understand this relationship and prepare for complications that may arise after infection. Several recent studies have shown a link between COVID-19 and coagulation. We propose several considerations for autopsies of unexpected fatal pulmonary embolism during the SARS-CoV-2 endemic period.
7.Quantifying Brain Atrophy Using a CSF-Focused Segmentation Approach
Kyoung Yoon LIM ; Seongbeom PARK ; Duk L. NA ; Sang Won SEO ; Min Young CHUN ; Kichang KWAK ;
Dementia and Neurocognitive Disorders 2025;24(2):115-125
Background:
and Purpose: Brain atrophy, characterized by sulcal widening and ventricular enlargement, is a hallmark of neurodegenerative diseases such as Alzheimer’s disease. Visual assessments are subjective and variable, while automated methods struggle with subtle intensity differences and standardization, highlighting limitations in both approaches. This study aimed to develop and evaluate a novel method focusing on cerebrospinal fluid (CSF) regions by assessing segmentation accuracy, detecting stage-specific atrophy patterns, and testing generalizability to unstandardized datasets.
Methods:
We utilized T1-weighted magnetic resonance imaging data from 3,315 participants from Samsung Medical Center and 1,439 participants from other hospitals. Segmentation accuracy was evaluated using the Dice similarity coefficient (DSC), and W-scores were calculated for each region of interest (ROI) to assess stage-specific atrophy patterns.
Results:
The segmentation demonstrated high accuracy, with average DSC values exceeding 0.9 for ventricular and hippocampal regions and above 0.8 for cortical regions. Significant differences in W-scores were observed across cognitive stages (cognitively unimpaired, mild cognitive impairment, dementia of Alzheimer’s type) for all ROIs (all, p<0.05). Similar trends were observed in the images from other hospitals, confirming the algorithm’s generalizability to datasets without prior standardization.
Conclusions
This study demonstrates the robustness and clinical applicability of a novel CSF-focused segmentation method for assessing brain atrophy. The method provides a scalable and objective framework for evaluating structural changes across cognitive stages and holds potential for broader application in neurodegenerative disease research and clinical practice.
8.Reproducibility of Plasma Biomarker Measurements Across Laboratories:Insights Into ptau217, GFAP, and NfL
Heekyoung KANG ; Sook-Young WOO ; Daeun SHIN ; Sohyun YIM ; Eun Hye LEE ; Hyunchul RYU ; Bora CHU ; Henrik ZETTERBERG ; Kaj BLENNOW ; Jihwan YUN ; Duk L NA ; Hee Jin KIM ; Hyemin JANG ; Jun Pyo KIM ;
Dementia and Neurocognitive Disorders 2025;24(2):91-101
Background:
and Purpose: Plasma biomarkers, including phosphorylated tau (ptau217), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL), are promising tools for detecting Alzheimer’s disease (AD) pathology. However, cross-laboratory reproducibility remains a challenge, even when using identical analytical platforms such as single-molecule array (Simoa). This study aimed to compare plasma biomarker measurements (ptau217, GFAP, and NfL) between 2 laboratories, the University of Gothenburg (UGOT) and DNAlink, and evaluate their associations with amyloid positron emission tomography (PET) imaging.
Methods:
Plasma biomarkers were measured using Simoa platforms at both laboratories:the UGOT and DNAlink Incorporation. Diagnostic performance for predicting amyloid PET positivity, cross-laboratory agreement, and the impact of normalization techniques were assessed. Bland-Altman plots and correlation analyses were employed to evaluate agreement and variability.
Results:
Plasma ptau217 concentrations exhibited strong correlations with amyloid PET global centiloid values, with comparable diagnostic performance between laboratories (area under the curve=0.94 for UGOT and 0.95 for DNAlink). Cross-laboratory agreement for ptau217 was excellent (r=0.96), improving further after natural log transformation. GFAP and NfL also demonstrated moderate to strong correlations (r=0.86 for GFAP and r=0.99 for NfL), with normalization reducing variability.
Conclusions
Plasma biomarker measurements were consistent across laboratories using identical Simoa platforms, with strong diagnostic performance and improved agreement after normalization. These findings support the scalability of plasma biomarkers for multicenter studies and underscore their potential for standardized applications in AD research and clinical practice.
9.Clinical Practice Guidelines for Dementia: Recommendations for Cholinesterase Inhibitors and Memantine
Yeshin KIM ; Dong Woo KANG ; Geon Ha KIM ; Ko Woon KIM ; Hee-Jin KIM ; Seunghee NA ; Kee Hyung PARK ; Young Ho PARK ; Gihwan BYEON ; Jeewon SUH ; Joon Hyun SHIN ; YongSoo SHIM ; YoungSoon YANG ; Yoo Hyun UM ; Seong-il OH ; Sheng-Min WANG ; Bora YOON ; Sun Min LEE ; Juyoun LEE ; Jin San LEE ; Jae-Sung LIM ; Young Hee JUNG ; Juhee CHIN ; Hyemin JANG ; Miyoung CHOI ; Yun Jeong HONG ; Hak Young RHEE ; Jae-Won JANG ;
Dementia and Neurocognitive Disorders 2025;24(1):1-23
Background:
and Purpose: This clinical practice guideline provides evidence-based recommendations for treatment of dementia, focusing on cholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists for Alzheimer’s disease (AD) and other types of dementia.
Methods:
Using the Population, Intervention, Comparison, Outcomes (PICO) framework, we developed key clinical questions and conducted systematic literature reviews. A multidisciplinary panel of experts, organized by the Korean Dementia Association, evaluated randomized controlled trials and observational studies. Recommendations were graded for evidence quality and strength using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology.
Results:
Three main recommendations are presented: (1) For AD, cholinesterase inhibitors (donepezil, rivastigmine, galantamine) are strongly recommended for improving cognition and daily function based on moderate evidence; (2) Cholinesterase inhibitors are conditionally recommended for vascular dementia and Parkinson’s disease dementia, with a strong recommendation for Lewy body dementia; (3) For moderate to severe AD, NMDA receptor antagonist (memantine) is strongly recommended, demonstrating significant cognitive and functional improvements. Both drug classes showed favorable safety profiles with manageable side effects.
Conclusions
This guideline offers standardized, evidence-based pharmacologic recommendations for dementia management, with specific guidance on cholinesterase inhibitors and NMDA receptor antagonists. It aims to support clinical decision-making and improve patient outcomes in dementia care. Further updates will address emerging treatments, including amyloid-targeting therapies, to reflect advances in dementia management.
10.Effect of Helicobacter pylori Eradication on Metabolic Parameters and Body Composition including Skeletal Muscle Mass: A Matched Case-Control Study
Suh Eun BAE ; Kee Don CHOI ; Jaewon CHOE ; Min Jung LEE ; Seonok KIM ; Ji Young CHOI ; Hana PARK ; Jaeil KIM ; Hye Won PARK ; Hye-Sook CHANG ; Hee Kyong NA ; Ji Yong AHN ; Kee Wook JUNG ; Jeong Hoon LEE ; Do Hoon KIM ; Ho June SONG ; Gin Hyug LEE ; Hwoon-Yong JUNG
Gut and Liver 2025;19(3):346-354
Background/Aims:
Findings on the impact of Helicobacter pylori eradication on metabolic parameters are inconsistent. This study aimed to evaluate the effects of H. pylori eradication on metabolic parameters and body composition, including body fat mass and skeletal muscle mass.
Methods:
We retrospectively reviewed the data of asymptomatic patients who underwent health screenings, including bioelectrical impedance analysis, before and after H. pylori eradication between 2005 and 2021. After matching individuals based on key factors, we compared lipid profiles, metabolic parameters, and body composition between 823 patients from the eradicated group and 823 patients from the non-eradicated groups.
Results:
Blood pressure, erythrocyte sedimentation rate, and glycated hemoglobin values were significantly lower in the eradicated group than in the non-eradicated group. However, changes in body mass index (BMI), body fat mass, appendicular skeletal muscle mass (ASM), waist circumference, and lipid profiles were not significantly different between the two groups. In a subgroup analysis of individuals aged >45 years, blood pressure, erythrocyte sedimentation rate, and glycated hemoglobin changes were significantly lower in the eradicated group than in the noneradicated group. BMI values were significantly higher in the eradicated group than in the noneradicated group; however, no significant differences were observed between the two groups regarding changes in body weight, body fat mass, ASM, or waist circumference. Total cholesterol and low-density lipoprotein cholesterol levels were significantly lower in the eradicated group than in non-eradicated group.
Conclusions
H. pylori eradication significantly reduced blood pressure, glucose levels, and systemic inflammation and improved lipid profiles in patients aged >45 years. BMI, body fat mass, ASM, and waist circumference did not significantly differ between patients in the eradicated group and those in the non-eradicated group.

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