1.The Differential Developmental Neurotoxicity of Valproic Acid on Anterior and Posterior Neural Induction of Human Pluripotent Stem Cells
Jeongah KIM ; Si-Hyung PARK ; Woong SUN
International Journal of Stem Cells 2025;18(1):49-58
Valproic acid (VPA), widely used as an antiepileptic drug, exhibits developmental neurotoxicity when exposure occurs during early or late pregnancy, resulting in various conditions ranging from neural tube defects to autism spectrum disorders. However, toxicity during the very early stages of neural development has not been addressed. Therefore, we investigated the effects of VPA in a model where human pluripotent stem cells differentiate into anterior or posterior neural tissues. Exposure to VPA during the induction of neural stem cells induced different developmental toxic effects in a dose-dependent manner. For instance, VPA induced cell death more profoundly during anteriorly guided neural progenitor induction, while inhibition of cell proliferation and enhanced differentiation were observed during posteriorly guided neural induction. Furthermore, acute exposure to VPA during the posterior induction step also retarded the subsequent neurulation-like tube morphogenesis process in neural organoid culture. These results suggest that VPA exposure during very early embryonic development might exhibit cytotoxicity and subsequently disrupt neural differentiation and morphogenesis processes.
2.The Differential Developmental Neurotoxicity of Valproic Acid on Anterior and Posterior Neural Induction of Human Pluripotent Stem Cells
Jeongah KIM ; Si-Hyung PARK ; Woong SUN
International Journal of Stem Cells 2025;18(1):49-58
Valproic acid (VPA), widely used as an antiepileptic drug, exhibits developmental neurotoxicity when exposure occurs during early or late pregnancy, resulting in various conditions ranging from neural tube defects to autism spectrum disorders. However, toxicity during the very early stages of neural development has not been addressed. Therefore, we investigated the effects of VPA in a model where human pluripotent stem cells differentiate into anterior or posterior neural tissues. Exposure to VPA during the induction of neural stem cells induced different developmental toxic effects in a dose-dependent manner. For instance, VPA induced cell death more profoundly during anteriorly guided neural progenitor induction, while inhibition of cell proliferation and enhanced differentiation were observed during posteriorly guided neural induction. Furthermore, acute exposure to VPA during the posterior induction step also retarded the subsequent neurulation-like tube morphogenesis process in neural organoid culture. These results suggest that VPA exposure during very early embryonic development might exhibit cytotoxicity and subsequently disrupt neural differentiation and morphogenesis processes.
3.The Differential Developmental Neurotoxicity of Valproic Acid on Anterior and Posterior Neural Induction of Human Pluripotent Stem Cells
Jeongah KIM ; Si-Hyung PARK ; Woong SUN
International Journal of Stem Cells 2025;18(1):49-58
Valproic acid (VPA), widely used as an antiepileptic drug, exhibits developmental neurotoxicity when exposure occurs during early or late pregnancy, resulting in various conditions ranging from neural tube defects to autism spectrum disorders. However, toxicity during the very early stages of neural development has not been addressed. Therefore, we investigated the effects of VPA in a model where human pluripotent stem cells differentiate into anterior or posterior neural tissues. Exposure to VPA during the induction of neural stem cells induced different developmental toxic effects in a dose-dependent manner. For instance, VPA induced cell death more profoundly during anteriorly guided neural progenitor induction, while inhibition of cell proliferation and enhanced differentiation were observed during posteriorly guided neural induction. Furthermore, acute exposure to VPA during the posterior induction step also retarded the subsequent neurulation-like tube morphogenesis process in neural organoid culture. These results suggest that VPA exposure during very early embryonic development might exhibit cytotoxicity and subsequently disrupt neural differentiation and morphogenesis processes.
4.The prevention and response to infectious diseases in long-term care facilities in Korea: a nationwide survey
Sun Hee NA ; Joong Sik EOM ; Sun Bean KIM ; Hyung Jin YOON ; So Yeon YOO ; Kyeong Sook CHA ; Jong Rim CHOI ; Ji Youn CHOI ; Si Hyeon HAN ; Jin Ju PARK ; Tark KIM ; Jacob LEE
Epidemiology and Health 2024;46(1):e2024084-
OBJECTIVES:
Long-term care facilities (LTCFs) are communal environments for patients with chronic diseases or older adults, making them particularly susceptible to significant harm during infectious disease outbreaks. Nonetheless, LTCFs have historically been subject to less stringent infection prevention and control (IPC) mandates. This study aimed to assess the current state of LTCFs and to develop an IPC system tailored for these facilities following the coronavirus disease 2019 (COVID-19) pandemic.
METHODS:
We conducted an online survey of 11,366 LTCFs in Korea from December 30, 2022 to January 20, 2023, to evaluate the components of IPC in LTCFs. The infectious diseases targeted for IPC included COVID-19, influenza, and scabies. Additionally, we compared institution-based and home-based long-term care insurance facilities.
RESULTS:
Overall, 3,537 (31.1%) LTCFs responded to the survey, comprising 1,819 (51.4%) institution-based and 1,718 (48.6%) home-based facilities. A majority (87.4%, 2,376/2,720) of these facilities experienced COVID-19 outbreaks. However, only 42.2% of home-based facilities, in contrast to 90.6% of institution-based facilities, were equipped to manage concurrent COVID-19 cases. Similarly, while 92.1% of institution-based facilities were capable of managing influenza, only 50.5% of home-based facilities could do the same. The incidence of scabies was significantly higher in institution-based facilities than in home-based ones (26.1 vs. 4.3%). Additionally, 88.7% of institution-based facilities managed scabies cases effectively, compared to only 42.1% of home-based facilities.
CONCLUSIONS
Approximately half of the LTCFs had a basic capacity to respond to infectious diseases. However, there were differences in response capabilities between institution-based facilities and home-based facilities.
5.The prevention and response to infectious diseases in long-term care facilities in Korea: a nationwide survey
Sun Hee NA ; Joong Sik EOM ; Sun Bean KIM ; Hyung Jin YOON ; So Yeon YOO ; Kyeong Sook CHA ; Jong Rim CHOI ; Ji Youn CHOI ; Si Hyeon HAN ; Jin Ju PARK ; Tark KIM ; Jacob LEE
Epidemiology and Health 2024;46(1):e2024084-
OBJECTIVES:
Long-term care facilities (LTCFs) are communal environments for patients with chronic diseases or older adults, making them particularly susceptible to significant harm during infectious disease outbreaks. Nonetheless, LTCFs have historically been subject to less stringent infection prevention and control (IPC) mandates. This study aimed to assess the current state of LTCFs and to develop an IPC system tailored for these facilities following the coronavirus disease 2019 (COVID-19) pandemic.
METHODS:
We conducted an online survey of 11,366 LTCFs in Korea from December 30, 2022 to January 20, 2023, to evaluate the components of IPC in LTCFs. The infectious diseases targeted for IPC included COVID-19, influenza, and scabies. Additionally, we compared institution-based and home-based long-term care insurance facilities.
RESULTS:
Overall, 3,537 (31.1%) LTCFs responded to the survey, comprising 1,819 (51.4%) institution-based and 1,718 (48.6%) home-based facilities. A majority (87.4%, 2,376/2,720) of these facilities experienced COVID-19 outbreaks. However, only 42.2% of home-based facilities, in contrast to 90.6% of institution-based facilities, were equipped to manage concurrent COVID-19 cases. Similarly, while 92.1% of institution-based facilities were capable of managing influenza, only 50.5% of home-based facilities could do the same. The incidence of scabies was significantly higher in institution-based facilities than in home-based ones (26.1 vs. 4.3%). Additionally, 88.7% of institution-based facilities managed scabies cases effectively, compared to only 42.1% of home-based facilities.
CONCLUSIONS
Approximately half of the LTCFs had a basic capacity to respond to infectious diseases. However, there were differences in response capabilities between institution-based facilities and home-based facilities.
6.The prevention and response to infectious diseases in long-term care facilities in Korea: a nationwide survey
Sun Hee NA ; Joong Sik EOM ; Sun Bean KIM ; Hyung Jin YOON ; So Yeon YOO ; Kyeong Sook CHA ; Jong Rim CHOI ; Ji Youn CHOI ; Si Hyeon HAN ; Jin Ju PARK ; Tark KIM ; Jacob LEE
Epidemiology and Health 2024;46(1):e2024084-
OBJECTIVES:
Long-term care facilities (LTCFs) are communal environments for patients with chronic diseases or older adults, making them particularly susceptible to significant harm during infectious disease outbreaks. Nonetheless, LTCFs have historically been subject to less stringent infection prevention and control (IPC) mandates. This study aimed to assess the current state of LTCFs and to develop an IPC system tailored for these facilities following the coronavirus disease 2019 (COVID-19) pandemic.
METHODS:
We conducted an online survey of 11,366 LTCFs in Korea from December 30, 2022 to January 20, 2023, to evaluate the components of IPC in LTCFs. The infectious diseases targeted for IPC included COVID-19, influenza, and scabies. Additionally, we compared institution-based and home-based long-term care insurance facilities.
RESULTS:
Overall, 3,537 (31.1%) LTCFs responded to the survey, comprising 1,819 (51.4%) institution-based and 1,718 (48.6%) home-based facilities. A majority (87.4%, 2,376/2,720) of these facilities experienced COVID-19 outbreaks. However, only 42.2% of home-based facilities, in contrast to 90.6% of institution-based facilities, were equipped to manage concurrent COVID-19 cases. Similarly, while 92.1% of institution-based facilities were capable of managing influenza, only 50.5% of home-based facilities could do the same. The incidence of scabies was significantly higher in institution-based facilities than in home-based ones (26.1 vs. 4.3%). Additionally, 88.7% of institution-based facilities managed scabies cases effectively, compared to only 42.1% of home-based facilities.
CONCLUSIONS
Approximately half of the LTCFs had a basic capacity to respond to infectious diseases. However, there were differences in response capabilities between institution-based facilities and home-based facilities.
7.The prevention and response to infectious diseases in long-term care facilities in Korea: a nationwide survey
Sun Hee NA ; Joong Sik EOM ; Sun Bean KIM ; Hyung Jin YOON ; So Yeon YOO ; Kyeong Sook CHA ; Jong Rim CHOI ; Ji Youn CHOI ; Si Hyeon HAN ; Jin Ju PARK ; Tark KIM ; Jacob LEE
Epidemiology and Health 2024;46(1):e2024084-
OBJECTIVES:
Long-term care facilities (LTCFs) are communal environments for patients with chronic diseases or older adults, making them particularly susceptible to significant harm during infectious disease outbreaks. Nonetheless, LTCFs have historically been subject to less stringent infection prevention and control (IPC) mandates. This study aimed to assess the current state of LTCFs and to develop an IPC system tailored for these facilities following the coronavirus disease 2019 (COVID-19) pandemic.
METHODS:
We conducted an online survey of 11,366 LTCFs in Korea from December 30, 2022 to January 20, 2023, to evaluate the components of IPC in LTCFs. The infectious diseases targeted for IPC included COVID-19, influenza, and scabies. Additionally, we compared institution-based and home-based long-term care insurance facilities.
RESULTS:
Overall, 3,537 (31.1%) LTCFs responded to the survey, comprising 1,819 (51.4%) institution-based and 1,718 (48.6%) home-based facilities. A majority (87.4%, 2,376/2,720) of these facilities experienced COVID-19 outbreaks. However, only 42.2% of home-based facilities, in contrast to 90.6% of institution-based facilities, were equipped to manage concurrent COVID-19 cases. Similarly, while 92.1% of institution-based facilities were capable of managing influenza, only 50.5% of home-based facilities could do the same. The incidence of scabies was significantly higher in institution-based facilities than in home-based ones (26.1 vs. 4.3%). Additionally, 88.7% of institution-based facilities managed scabies cases effectively, compared to only 42.1% of home-based facilities.
CONCLUSIONS
Approximately half of the LTCFs had a basic capacity to respond to infectious diseases. However, there were differences in response capabilities between institution-based facilities and home-based facilities.
8.Prevention of Cytomegalovirus Infection in Solid Organ Transplant Recipients:Guidelines by the Korean Society of Infectious Diseases and the Korean Society for Transplantation
Kyungmin HUH ; Sang-Oh LEE ; Jungok KIM ; Su Jin LEE ; Pyoeng Gyun CHOE ; Ji-Man KANG ; Jaeseok YANG ; Heungsup SUNG ; Si-Ho KIM ; Chisook MOON ; Hyeri SEOK ; Hye Jin SHI ; Yu Mi WI ; Su Jin JEONG ; Wan Beom PARK ; Youn Jeong KIM ; Jongman KIM ; Hyung Joon AHN ; Nam Joong KIM ; Kyong Ran PECK ; Myoung Soo KIM ; Sang Il KIM
Infection and Chemotherapy 2024;56(1):101-121
Cytomegalovirus (CMV) is the most important opportunistic viral pathogen in solid organ transplant (SOT) recipients.The Korean guideline for the prevention of CMV infection in SOT recipients was developed jointly by the Korean Society for Infectious Diseases and the Korean Society of Transplantation. CMV serostatus of both donors and recipients should be screened before transplantation to best assess the risk of CMV infection after SOT. Seronegative recipients receiving organs from seropositive donors face the highest risk, followed by seropositive recipients. Either antiviral prophylaxis or preemptive therapy can be used to prevent CMV infection. While both strategies have been demonstrated to prevent CMV infection post-transplant, each has its own advantages and disadvantages. CMV serostatus, transplant organ, other risk factors, and practical issues should be considered for the selection of preventive measures. There is no universal viral load threshold to guide treatment in preemptive therapy. Each institution should define and validate its own threshold.Valganciclovir is the favored agent for both prophylaxis and preemptive therapy. The evaluation of CMV-specific cellmediated immunity and the monitoring of viral load kinetics are gaining interest, but there was insufficient evidence to issue recommendations. Specific considerations on pediatric transplant recipients are included.
9.Guidelines for Manufacturing and Application of Organoids: Brain
Taehwan KWAK ; Si-Hyung PARK ; Siyoung LEE ; Yujeong SHIN ; Ki-Jun YOON ; Seung-Woo CHO ; Jong-Chan PARK ; Seung-Ho YANG ; Heeyeong CHO ; Heh-In IM ; Sun-Ju AHN ; Woong SUN ; Ji Hun YANG
International Journal of Stem Cells 2024;17(2):158-181
This study offers a comprehensive overview of brain organoids for researchers. It combines expert opinions with technical summaries on organoid definitions, characteristics, culture methods, and quality control. This approach aims to enhance the utilization of brain organoids in research. Brain organoids, as three-dimensional human cell models mimicking the nervous system, hold immense promise for studying the human brain. They offer advantages over traditional methods, replicating anatomical structures, physiological features, and complex neuronal networks. Additionally, brain organoids can model nervous system development and interactions between cell types and the microenvironment. By providing a foundation for utilizing the most human-relevant tissue models, this work empowers researchers to overcome limitations of two-dimensional cultures and conduct advanced disease modeling research.
10.Extremely Severe Dysphagia Secondary to Tracheostomy: A Case Report
Daham KIM ; Bum-Seok LEE ; Si-Woon PARK ; Hyung-Wook HAN ; Namo JEON ; Hyeon-Woo JEON ; Doo Young KIM
Journal of the Korean Dysphagia Society 2023;13(1):65-70
We report an extremely severe case of dysphagia in an elderly patient. Tracheostomy alone was found to be the cause of severe upper esophageal opening dysfunction. An 84-year-old woman was admitted with dyspnea. During hospitalization, she had respiratory failure and underwent a tracheostomy. On day 41 in the hospital, she complained of dysphagia and was a swallowing evaluation was done at the rehabilitation department. We ruled out other etiologies of upper esophageal dysfunction through a brain magnetic resonance imaging (MRI) and endoscopic evaluation. Through follow-up tests, it was found retrospectively that extreme dysphagia could have occurred through the following mechanism: the airway was not protected at the time of the tracheostomy because the movement of the epiglottis did not appear to be normal. This was due to the reduction in laryngeal function affecting the upper esophageal opening after the tracheostomy, and at the same time, the power to push the bolus was weak. After 6 months, at the third test, she had improved enough to ingest a soft diet and fluid with thickeners, so she was able to start an oral diet without decannulation. It is thus important to recognize that tracheostomy alone can cause extremely severe aspiration. If these findings are observed in patients undergoing tracheostomy, it is necessary to check the movements of the epiglottis properly and evaluate whether the condition can be improved by rehabilitation treatment.

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