1.A Novel Visualization Method for Sleep Spindles Based on Source Localization of High Density EEG.
Soohyun LEE ; Seunghwan KIM ; Jee Hyun CHOI
Experimental Neurobiology 2017;26(6):362-368
Equivalent dipole source localization is a well-established approach to localizing the electrical activity in electroencephalogram (EEG). So far, source localization has been used primarily in localizing the epileptic source in human epileptic patients. Currently, source localization techniques have been applied to account for localizing epileptic source among the epileptic patients. Here, we present the first application of source localization in the field of sleep spindle in mouse brain. The spatial distribution of cortical potential was obtained by high density EEG and then the anterior and posterior sleep spindles were classified based on the K-mean clustering algorithm. To solve the forward problem, a realistic geometry brain model was produced based on boundary element method (BEM) using mouse MRI. Then, we applied four different source estimation algorithms (minimum norm, eLORETA, sLORETA, and LORETA) to estimate the spatial location of equivalent dipole source of sleep spindles. The estimated sources of anterior and posterior spindles were plotted in a cine-mode that revealed different topographic patterns of spindle propagation. The characterization of sleep spindles may be better be distinguished by our novel visualization method.
Animals
;
Brain
;
Electroencephalography*
;
Humans
;
Insulator Elements
;
Magnetic Resonance Imaging
;
Methods*
;
Mice
2.NADPH oxidase inhibitor development for diabetic nephropathy through water tank model
Hye Eun LEE ; Seunghwan SHIM ; Yongseok CHOI ; Yun Soo BAE
Kidney Research and Clinical Practice 2022;41(Suppl 2):S89-S98
Oxidative stress can cause generation of uncontrolled reactive oxygen species (ROS) and lead to cytotoxic damage to cells and tissues. Recently, it has been shown that transient ROS generation can serve as a secondary messenger in receptor-mediated cell signaling. Although excessive levels of ROS are harmful, moderated levels of ROS are essential for normal physiological function. Therefore, regulating cellular ROS levels should be an important concept for development of novel therapeutics for treating diseases. The overexpression and hyperactivation of NADPH oxidase (Nox) can induce high levels of ROS, which are strongly associated with diabetic nephropathy. This review discusses the theoretical basis for development of the Nox inhibitor as a regulator of ROS homeostasis to provide emerging therapeutic opportunities for diabetic nephropathy.
3.Intermittent, Non Cyclic Severe Mechanical Aortic Valve Regurgitation.
Jong Hyun CHOI ; Jung Hyun CHOI ; Seunghwan SONG ; Myung Yong LEE
Journal of Cardiovascular Ultrasound 2013;21(4):189-191
Mechanical aortic prosthesis dysfunction can result from thrombosis or pannus formation. We describe an unusual case of intermittent, non cyclic mechanical aortic prosthesis dysfunction due to pannus formation with thrombus in the absence of systolic restriction of disk excursion, that presented with intermittent severe aortic regurgitation.
Aortic Valve Insufficiency
;
Aortic Valve*
;
Echocardiography
;
Prostheses and Implants
;
Thrombosis
4.Upper Limb Ischemia: Clinical Experiences of Acute and Chronic Upper Limb Ischemia in a Single Center.
Miju BAE ; Sung Woon CHUNG ; Chung Won LEE ; Jinseok CHOI ; Seunghwan SONG ; Sang Pil KIM
The Korean Journal of Thoracic and Cardiovascular Surgery 2015;48(4):246-251
BACKGROUND: Upper limb ischemia is less common than lower limb ischemia, and relatively few cases have been reported. This paper reviews the epidemiology, etiology, and clinical characteristics of upper limb ischemia and analyzes the factors affecting functional sequelae after treatment. METHODS: The records of 35 patients with acute and chronic upper limb ischemia who underwent treatment from January 2007 to December 2012 were retrospectively reviewed. RESULTS: The median age was 55.03 years, and the number of male patients was 24 (68.6%). The most common etiology was embolism of cardiac origin, followed by thrombosis with secondary trauma, and the brachial artery was the most common location for a lesion causing obstruction. Computed tomography angiography was the first-line diagnostic tool in our center. Twenty-eight operations were performed, and conservative therapy was implemented in seven cases. Five deaths (14.3%) occurred during follow-up. Twenty patients (57.1%) complained of functional sequelae after treatment. Functional sequelae were found to be more likely in patients with a longer duration of symptoms (odds ratio, 1.251; p=0.046) and higher lactate dehydrogenase (LDH) levels (odds ratio, 1.001; p=0.031). CONCLUSION: An increased duration of symptoms and higher initial serum LDH levels were associated with the more frequent occurrence of functional sequelae. The prognosis of upper limb ischemia is associated with prompt and proper treatment and can also be predicted by initial serum LDH levels.
Angiography
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Brachial Artery
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Embolism
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Epidemiology
;
Follow-Up Studies
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Humans
;
Ischemia*
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L-Lactate Dehydrogenase
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Lower Extremity
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Male
;
Prognosis
;
Retrospective Studies
;
Thrombosis
;
Upper Extremity*
5.Postnatal Left Ventricular Outflow Tract Obstruction Caused by Multiple Rhabdomyoma Tumors.
Seunghwan SONG ; Tae Gook JUN ; Min Suk CHOI ; Ji Hyuk YANG
The Korean Journal of Thoracic and Cardiovascular Surgery 2010;43(6):725-728
Rhabdomyoma is the most common benign cardiac neoplasm in neonates. Most patients with rhabdomyoma experienced spontaneous regression. Yet some of them need surgical therapy because of hemodynamic problems of the heart such as arrhythmia, outflow tract obstruction and valvular dysfunction. We found multiple masses in both ventricles on the patient's fetal echocardiogram. Heart failure caused by severe left ventricular outflow tract obstruction quickly presented after birth. The mass interfering with the outflow tract was resected via the transaortic approach at the first day of birth. Postoperative echocardiography showed complete release of the outflow tract obstruction. He was discharged on the postoperative day 8. During the 3 years of follow up, we found that the sizes of the remnant masses had gradually decreased.
Arrhythmias, Cardiac
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Echocardiography
;
Follow-Up Studies
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Heart
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Heart Failure
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Heart Neoplasms
;
Hemodynamics
;
Humans
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Infant, Newborn
;
Parturition
;
Rhabdomyoma
6.Evaluation of Zone 2 Thoracic Endovascular Aortic Repair Performed with and without Prophylactic Embolization of the Left Subclavian Artery in Patients with Traumatic Aortic Injury
Miju BAE ; Chang Ho JEON ; Hoon KWON ; Jin Hyeok KIM ; Seon Uoo CHOI ; Seunghwan SONG
Korean Journal of Radiology 2021;22(4):577-583
Objective:
To report the authors’ experience in performing thoracic endovascular aortic repair (TEVAR) for zone 2 lesions after traumatic aortic injury (TAI).
Materials and Methods:
This retrospective review included 10 patients who underwent zone 2 TEVAR after identification of aortic isthmus injury by CT angiography (CTA) upon arrival at the emergency room of a regional trauma center from 2016 to 2019. Patients were classified into two groups: those who underwent left subclavian artery (LSA) embolization concurrently with the main TEVAR procedure, and those in whom LSA embolization was not performed during the main procedure, but was planned as a bailout treatment if type II endoleak was noted on follow-up CTA images. Pre-procedural and procedurerelated factors and post-procedure prognosis were compared between the groups.
Results:
There were no differences in pre-procedural factors, occurrence of endoleaks, and post-procedure prognosis (including mortality) between patients in the two groups. The duration of the procedure was shorter in the non-LSA embolization group (61 minutes vs. 27 minutes, p = 0.012). During follow-up, type II endoleak did not occur in either group.
Conclusion
Delaying preventative LSA embolization until stabilization of the patient would be desirable when performing zone 2 TEVAR for TAI, in the absence of endoleak on the completion aortography image taken after complete deployment of the stent graft.
7.Global Cerebral Ischemia-induced Depression Accompanies Alteration of Neuronal Excitability in the Infralimbic Cortex Layer 2/3 Pyramidal Neurons
Dong Cheol JANG ; Seunghwan CHOI ; Geehoon CHUNG ; Sun Kwang KIM
Experimental Neurobiology 2023;32(4):302-312
Cerebral ischemia can lead to a range of sequelae, including depression. The pathogenesis of depression involves neuronal change of the medial prefrontal cortex (mPFC). However, how cerebral ischemia-induced changes manifest across subregions and layers of the mPFC is not well understood. In this study, we induced cerebral ischemia in mice via transient bilateral common carotid artery occlusion (tBCCAO) and observed depressive-like behavior. Using whole-cell patch clamp recording, we identified changes in the excitability of pyramidal neurons in the prelimbic cortex (PL) and infralimbic cortex (IL), the subregions of mPFC. Compared to sham control mice, tBCCAO mice showed significantly reduced neuronal excitability in IL layer 2/3 but not layer 5 pyramidal neurons, accompanied by increased rheobase current and decreased input resistance. In contrast, no changes were observed in the excitability of PL layer 2/3 and layer 5 pyramidal neurons. Our results provide a new direction for studying the pathogenesis of depression following ischemic damage by showing that cerebral ischemia induces subregion- and layer-specific changes in the mPFC pyramidal neurons.
8.Evaluation of Zone 2 Thoracic Endovascular Aortic Repair Performed with and without Prophylactic Embolization of the Left Subclavian Artery in Patients with Traumatic Aortic Injury
Miju BAE ; Chang Ho JEON ; Hoon KWON ; Jin Hyeok KIM ; Seon Uoo CHOI ; Seunghwan SONG
Korean Journal of Radiology 2021;22(4):577-583
Objective:
To report the authors’ experience in performing thoracic endovascular aortic repair (TEVAR) for zone 2 lesions after traumatic aortic injury (TAI).
Materials and Methods:
This retrospective review included 10 patients who underwent zone 2 TEVAR after identification of aortic isthmus injury by CT angiography (CTA) upon arrival at the emergency room of a regional trauma center from 2016 to 2019. Patients were classified into two groups: those who underwent left subclavian artery (LSA) embolization concurrently with the main TEVAR procedure, and those in whom LSA embolization was not performed during the main procedure, but was planned as a bailout treatment if type II endoleak was noted on follow-up CTA images. Pre-procedural and procedurerelated factors and post-procedure prognosis were compared between the groups.
Results:
There were no differences in pre-procedural factors, occurrence of endoleaks, and post-procedure prognosis (including mortality) between patients in the two groups. The duration of the procedure was shorter in the non-LSA embolization group (61 minutes vs. 27 minutes, p = 0.012). During follow-up, type II endoleak did not occur in either group.
Conclusion
Delaying preventative LSA embolization until stabilization of the patient would be desirable when performing zone 2 TEVAR for TAI, in the absence of endoleak on the completion aortography image taken after complete deployment of the stent graft.
9.Low-frequency auricular vagus nerve stimulation facilitates cerebrospinal fluid influx by promoting vasomotion
Seunghwan CHOI ; In Seon BAEK ; Kyungjoon LEE ; Sun Kwang KIM
The Korean Journal of Physiology and Pharmacology 2025;29(1):109-116
Auricular vagus nerve stimulation (aVNS) is one of the promising neuromodulation techniques due to its non-invasiveness, convenience, and effectiveness. aVNS has been suggested as a potential treatment for neurodegenerative diseases showing impaired cerebrospinal fluid (CSF) dynamics. Improving CSF flow has been proposed as a key mechanism of the therapeutic effect on neurodegenerative diseases. However, aVNS parameters have been set empirically and the effective parameter that maximize the effect remains elusive. Here we show that 30 minutes of low-frequency aVNS increased arterial vasomotion events and enhanced cortical CSF influx along the branches of middle cerebral arteries. By using in vivo two photon imaging or widefield fluorescence microscopy with plasma and CSF tracers for visualizing blood vessels and perivascular spaces, arterial vasomotion and cortical CSF influx dynamics were acquired. The low-frequency (2 Hz) aVNS, but not middleand high-frequency (40 and 100 Hz) aVNS, significantly increased the number of vasomotion events compared to the sham group. Accordingly, in the CSF imaging, 2 Hz of aVNS markedly enhanced the CSF influx. Our findings demonstrate that lowfrequency aVNS is the effective parameter in respect to modulating vasomotion and CSF influx, resulting in brain clearance effect.
10.Low-frequency auricular vagus nerve stimulation facilitates cerebrospinal fluid influx by promoting vasomotion
Seunghwan CHOI ; In Seon BAEK ; Kyungjoon LEE ; Sun Kwang KIM
The Korean Journal of Physiology and Pharmacology 2025;29(1):109-116
Auricular vagus nerve stimulation (aVNS) is one of the promising neuromodulation techniques due to its non-invasiveness, convenience, and effectiveness. aVNS has been suggested as a potential treatment for neurodegenerative diseases showing impaired cerebrospinal fluid (CSF) dynamics. Improving CSF flow has been proposed as a key mechanism of the therapeutic effect on neurodegenerative diseases. However, aVNS parameters have been set empirically and the effective parameter that maximize the effect remains elusive. Here we show that 30 minutes of low-frequency aVNS increased arterial vasomotion events and enhanced cortical CSF influx along the branches of middle cerebral arteries. By using in vivo two photon imaging or widefield fluorescence microscopy with plasma and CSF tracers for visualizing blood vessels and perivascular spaces, arterial vasomotion and cortical CSF influx dynamics were acquired. The low-frequency (2 Hz) aVNS, but not middleand high-frequency (40 and 100 Hz) aVNS, significantly increased the number of vasomotion events compared to the sham group. Accordingly, in the CSF imaging, 2 Hz of aVNS markedly enhanced the CSF influx. Our findings demonstrate that lowfrequency aVNS is the effective parameter in respect to modulating vasomotion and CSF influx, resulting in brain clearance effect.