Jung Keun Hyun - Academia.edu (original) (raw)

Papers by Jung Keun Hyun

Sensors

Motion classification can be performed using biometric signals recorded by electroencephalography... more Motion classification can be performed using biometric signals recorded by electroencephalography (EEG) or electromyography (EMG) with noninvasive surface electrodes for the control of prosthetic arms. However, current single-modal EEG and EMG based motion classification techniques are limited owing to the complexity and noise of EEG signals, and the electrode placement bias, and low-resolution of EMG signals. We herein propose a novel system of two-dimensional (2D) input image feature multimodal fusion based on an EEG/EMG-signal transfer learning (TL) paradigm for detection of hand movements in transforearm amputees. A feature extraction method in the frequency domain of the EEG and EMG signals was adopted to establish a 2D image. The input images were used for training on a model based on the convolutional neural network algorithm and TL, which requires 2D images as input data. For the purpose of data acquisition, five transforearm amputees and nine healthy controls were recruited...

Annals of Rehabilitation Medicine, 2020

Objective To investigate the comprehensive outcomes in aphasic patients, including their cognitiv... more Objective To investigate the comprehensive outcomes in aphasic patients, including their cognitive and functional status after ischemic or hemorrhagic stroke. It also aimed to clarify whether aphasia is a prognostic factor for cognitive and functional improvements in stroke patients.Methods Sixty-seven ischemic or hemorrhagic stroke patients in the subacute stage who had been diagnosed with aphasia using the Korean version of Frenchay Aphasia Screening Test (K-FAST) were included in the study. Forty-six stroke patients without aphasia were used as controls. All patients were examined with the Korean version of the Western Aphasia Battery (K-WAB). Cognitive and functional assessments of the patients including the Korean version of Mini-Mental State Examination (K-MMSE), and the Korean version of Modified Barthel Index (K-MBI) were performed during admission and 4 weeks after the initial assessments.Results The initial and follow-up total K-MMSE and K-MBI scores were significantly low...

Journal of korean Academy of Child and Adolescent Psychiatry, 2013

Botulinum toxin, a neurotoxin, is known to be an inhibitor of cholinergic neuromuscular transmiss... more Botulinum toxin, a neurotoxin, is known to be an inhibitor of cholinergic neuromuscular transmission. Recently, it was reported that the administration of botulinum toxin is effective for the treatment of focal neurological motor disorders such as cervical dystonia, blepharospasm, hemifacial spasm, spasmodic dysphonia, and writer's cramp. Several case studies reported that the botulinum toxin was administered for the treatment of motor tic or vocal tic. It was found that this toxin reduces the frequency and severity of the tic as well as the premonitory urge and symptoms. In our case study, a noticeable decrease of motor tic symptom was observed after an intramuscular injection of 300mg of botulinum toxin in an 18-year-old patient with Tourette's disorder who showed only a little improvement of motor tic and vocal tic symptoms after treatment with antipsychotic drugs for several years. This case is reported in our study and literature survey was undertaken for reviewing similar cases. In our study, an 18-year-old boy diagnosed with Tourette's disorder based on Diagnostic and Statistical Manual of Mental Disorders, fourth edition presented with the following scores : the Clinical Global Impression scale, Yale Global Tic Severity Scale (motor/vocal/severity), Premonitory Urge Score, Korean Attention-Deficit Hyperactivity Disorder Rating scale, and Kovac Depression scale which were performed prior to the treatment were 5, 21/5/50, 100, 17, and 18 points, respectively. Two weeks after the injection of botulinum toxin, the scores were 4, 17/5/40, 50, 16, and 19 points, respectively. Eight weeks after the injection of botulinum toxin, they had become 3, 15/5/30, 25, 16, and 20 points, respectively, which clearly indicates a noticeable decrease of motor tic symptom.

Archives of Hand and Microsurgery, 2019

Purpose: Peripheral nerve allograft can be an acceptable alternative, but it has not yet become c... more Purpose: Peripheral nerve allograft can be an acceptable alternative, but it has not yet become clinically useful because of immune response to foreign tissue. With significant advances in the research and tissue engineering, various alternatives to nerve autograft including synthetic nerve conduit and decellularization have been used, but their therapeutic effects were not satisfactory. The purpose of this study was to confirm the effectiveness of cryopreservation of the allograft nerve as a useful nerve-graft substitute. Methods: A total of 39 Sprague-Dawley rats (recipient) and 13 Lewis rats (donor) weighing 200 g to 300 g were used in this study. Animals were randomly divided 3 groups and received ipsilateral sciatic nerve graft: autograft (group 1), allograft (group 2), and cryopreserved nerve allograft (group 3), Nerve regeneration was evaluated at sixteen weeks on the basis of the animal weight, ankle contracture angle, compound muscle action potential, isometric tetanic muscle force, wet muscle weight of the tibialis anterior muscle, and the histomorphometry. Results: Cryopreserved nerve allograft (group 3) showed superior motor recovery than allograft group (group 2), which was comparable to those of autograft (group 1). Conclusion: Pretreatment of nerve allograft using cryopreservation decreased rejection caused by immune response of the donor and improved motor nerve recovery. In clinical perspective, use of a pretreated nerve allograft can be an alternative to the autograft.

Cell Reports, 2019

Highlights d Individually expressed BKSM generate iNSCs without a transient pluripotent state d P... more Highlights d Individually expressed BKSM generate iNSCs without a transient pluripotent state d Polycistronic BKSM expression produces a Brn4-Klf4 fusion protein d The Brn4-Klf4 fusion protein gains the ability to induce pluripotency d A shift in Brn4 binding from OctOct to SoxOct motif enables induction of pluripotency

Annals of rehabilitation medicine, 2018

Prolonged intubation is known to bring on postextubation dysphagia (PED) in some patients. We hav... more Prolonged intubation is known to bring on postextubation dysphagia (PED) in some patients. We have noted that there were some studies to investigate specific type and pattern of PED, which showed large variety of different swallowing abnormalities as mechanisms of PED that are multifactorial. There are several options of treatment in accordance with the management of these abnormalities. A botulinum toxin (BoT) injection into the upper esophageal sphincter (UES) can improve swallowing functions for patients with this disorder, by working to help the muscle relax. In this case, the conventional treatment was not effective in patients with PED, whereas the BoT injection made a great improvement for these patients. This study suggests that the UES pathology could be the main cause of PED.

Annals of rehabilitation medicine, 2017

To delineate the effect of early cranioplasty on the recovery of cognitive and functional impairm... more To delineate the effect of early cranioplasty on the recovery of cognitive and functional impairments in patients who received decompressive craniectomy after traumatic brain injury or spontaneous cerebral hemorrhage. Twenty-four patients who had received cranioplasty were selected and divided according to the period from decompressive craniectomy to cranioplasty into early (≤90 days) and late (>90 days) groups. The Korean version of the Mini-Mental State Examination (K-MMSE), Korean version of the Modified Barthel Index (K-MBI), and Functional Independence Measure (FIM) were evaluated at admission just after decompressive craniectomy and during the follow-up period after cranioplasty. Twelve patients were included in the early group, and another 13 patients were included in the late group. The age, gender, type of lesion, and initial K-MMSE, K-MBI, and FIM did not significantly differ between two groups. However, the total gain scores of the K-MMSE and FIM in the early group (4....

Stem cells international, 2016

Neural stem cells (NSCs) have a high potency for differentiation to neurons and glial cells for r... more Neural stem cells (NSCs) have a high potency for differentiation to neurons and glial cells for replacement of damaged cells and paracrine effects for the regeneration and remyelination of host axons. Dental pulp is known to have a potential to differentiate into neural-like cells; therefore, dental pulp may be used as an autologous cell source for neural repair. In this study, we selectively expanded stem cells from human dental pulp in an initial culture using NSC media under xeno- and serum-free conditions. At the initial step of primary culture, human dental pulp was divided into two groups according to the culture media: 10% fetal bovine serum medium group (FBS group) and NSC culture medium group (NSC group). In the NSC group relative to the FBS group, the expression of NSC markers and the concentrations of leukemia inhibitory factor, nerve growth factor, and stem cell factor were higher, although their expression levels were lower than those of human fetal NSCs. The transplant...

The Korean Journal of Hematology, 2008

A 67-year-old man developed swelling of the right leg with inguinal and abdominal pain over a per... more A 67-year-old man developed swelling of the right leg with inguinal and abdominal pain over a period of 5 days. Excisional biopsy of the left supraclavicular lymph nodes revealed the diffuse, large B cell type of malignant lymphoma. After chemotherapy, he complained of a tingling sensation and weakness in the left upper extremity, and then this progressed to quadriplegia. Electrodiagnostic testing demonstrated the characteristic findings of demyelination, which was consistent with Guillain-Barre syndrome (GBS). Non-Hodgkin's Lymphoma (NHL) leading to GBS, as was observed in the present case, suggests that physicians should be aware of GBS and non-Hodgkin's lymphoma as the full spectrum of these diseaseshas not been fully defined.

Annals of rehabilitation medicine, 2015

To elucidate the association between glycemic control status and clinical outcomes in patients wi... more To elucidate the association between glycemic control status and clinical outcomes in patients with acute ischemic stroke limited to the deep branch of the middle cerebral artery (MCA). We evaluated 65 subjects with first-ever ischemic stroke of the deep branches of the MCA, which was confirmed by magnetic resonance angiography. All subjects had blood hemoglobin A1c (HbA1c) measured at admission. They were classified into two groups according to the level of HbA1c (low <7.0% or high ≥7.0%). Neurological impairment and functional status were evaluated using the National Institutes of Health Stroke Scale (NIHSS), Functional Independence Measure (FIM), Korean version of Modified Barthel Index (K-MBI), Korean version of Mini-Mental State Examination (MMSE-K), and the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) at admission and discharge. Body mass index, serum glucose, homocysteine and cholesterol levels were also measured at admission. The two groups did not show a...

Annals of Rehabilitation Medicine, 2015

Objective To investigate the association of family history of stroke with functional outcomes in ... more Objective To investigate the association of family history of stroke with functional outcomes in stroke patients in Korea. Methods A case-control study was conducted. A total of 170 patients who were admitted to a rehabilitation unit were included. Risk factors for stroke such as age, sex, diabetes mellitus, hypertension, atrial fibrillation, smoking, high blood cholesterol and homocysteine level, obesity, and family history of stroke were taken into account. Stroke subtypes were the following: large vessel infarct, small vessel infarct, embolic infarct, subarachnoid hemorrhage, and intracranial hemorrhage. Stroke severity as assessed with the National Institutes of Health Stroke Scale (NIHSS), functional outcomes using the Korean version of the Modified Barthel index (K-MBI), Functional Independence Measurement (FIM), and cognitive function using the Korean version of Mini-Mental State Examination (K-MMSE) were assessed at admission and discharge. Results Subjects with a family history of stroke were more likely to have an ischemic stroke (90.7%) than were those without a family history (70.9%). The K-MBI, FIM, NIHSS, and K-MMSE scores did not show significant differences between patients with or without family history. Conclusion Family history of stroke was significantly associated with ischemic stroke, but not with functional outcomes. Other prognostic factors of stroke were not distributed differently between patients included in this study with or without a family history of stroke.

Journal of biological engineering, 2015

In the field of biomedical engineering, many studies have focused on the possible applications of... more In the field of biomedical engineering, many studies have focused on the possible applications of graphene and related nanomaterials due to their potential for use as scaffolds, coating materials and delivery carriers. On the other hand, electrospun nanofiber matrices composed of diverse biocompatible polymers have attracted tremendous attention for tissue engineering and regenerative medicine. However, their combination is intriguing and still challenging. In the present study, we fabricated nanofiber matrices composed of M13 bacteriophage with RGD peptide displayed on its surface (RGD-M13 phage) and poly(lactic-co-glycolic acid, PLGA) and characterized their physicochemical properties. In addition, the effect of graphene oxide (GO) on the cellular behaviors of C2C12 myoblasts, which were cultured on PLGA decorated with RGD-M13 phage (RGD/PLGA) nanofiber matrices, was investigated. Our results revealed that the RGD/PLGA nanofiber matrices have suitable physicochemical properties as...

Journal of nanobiotechnology, Jan 12, 2015

Electrospinning is a simple and effective method for fabricating micro- and nanofiber matrices. E... more Electrospinning is a simple and effective method for fabricating micro- and nanofiber matrices. Electrospun fibre matrices have numerous advantages for use as tissue engineering scaffolds, such as high surface area-to-volume ratio, mass production capability and structural similarity to the natural extracellular matrix (ECM). Therefore, electrospun matrices, which are composed of biocompatible polymers and various biomaterials, have been developed as biomimetic scaffolds for the tissue engineering applications. In particular, graphene oxide (GO) has recently been considered as a novel biomaterial for skeletal muscle regeneration because it can promote the growth and differentiation of myoblasts. Therefore, the aim of the present study was to fabricate the hybrid fibre matrices that stimulate myoblasts differentiation for skeletal muscle regeneration. Hybrid fibre matrices composed of poly(lactic-co-glycolic acid, PLGA) and collagen (Col) impregnated with GO (GO-PLGA-Col) were succes...

Annals of Rehabilitation Medicine, 2011

Collet-Sicard syndrome is a rare condition characterized by the unilateral paralysis of the 9th t... more Collet-Sicard syndrome is a rare condition characterized by the unilateral paralysis of the 9th through 12th cranial nerves. We describe a case of a 46-year-old man who presented with dysphagia after a falling down injury. Computed tomography demonstrated burst fracture of the atlas. Physical examination revealed decreased gag reflex on the left side, decreased laryngeal elevation, tongue deviation to the left side, and atrophy of the left trapezius muscle. Videofl uoroscopic swallowing study (VFSS) revealed frequent aspirations of a massive amount of thick liquid and incomplete opening of the upper esophageal sphincter during the pharyngeal phase. We report a rare case of Collet-Sicard syndrome caused by Jeff erson fracture.

Acta biomaterialia, 2015

Carbon nanotubes (CNTs), with their unique and unprecedented properties, have become very popular... more Carbon nanotubes (CNTs), with their unique and unprecedented properties, have become very popular for the repair of tissues, particularly for those requiring electrical stimuli. Whilst most reports have demonstrated in vitro neural cell responses of the CNTs, few studies have been performed on the in vivo efficacy of CNT-interfaced biomaterials in the repair and regeneration of neural tissues. Thus, we report here for the first time the in vivo functions of CNT-interfaced nerve conduits in the regeneration of transected rat sciatic nerve. Aminated CNTs were chemically tethered onto the surface of aligned phosphate glass microfibers (PGFs) and CNT-interfaced PGFs (CNT-PGFs) were successfully placed into three-dimensional poly(L/D-lactic acid) (PLDLA) tubes. An in vitro study confirmed that neurites of dorsal root ganglion outgrew actively along the aligned CNT-PGFs and that the CNT interfacing significantly increased the maximal neurite length. Sixteen weeks after implantation of a C...

Annals of rehabilitation medicine, 2012

To investigate swallowing laterality in hemiplegic patients with stroke and recovery of dysphagia... more To investigate swallowing laterality in hemiplegic patients with stroke and recovery of dysphagia according to the laterality. The sample was comprised of 46 dysphagic patients with hemiplegia after their first stroke. The sample's videofluoroscopic swallowing study (VFSS) was reviewed. Swallowing laterality was determined by the anterior-posterior view of VFSS. We measured width difference of barium sulfate liquid flow in the pharyngoesophageal segment. If there was double or more the width of that from the opposite width in the pharyngoesophageal segment more than twice on three trials of swallowing, then it was judged as having laterality. Subjects were assigned to no laterality (NL), laterality that is ipsilateral to hemiplegic side (LI), and laterality that is contralateral to hemiplegic side (LC) groups. We measured the following: prevalence of aspiration, the 8-point penetration-aspiration scale, and the functional dysphagia scale of the subjects at baseline and follow up...

Annals of Rehabilitation Medicine, 2013

Objective To clarify the relationship of skin temperature changes to clinical, radiologic, and el... more Objective To clarify the relationship of skin temperature changes to clinical, radiologic, and electrophysiological findings in unilateral lumbosacral radiculopathy and to delineate the possible temperature-change mechanisms involved. Methods One hundred and one patients who had clinical symptoms and for whom there were physical findings suggestive or indicative of unilateral lumbosacral radiculopathy, along with 27 normal controls, were selected for the study, and the thermal-pattern results of digital infrared thermographic imaging (DITI) performed on the back and lower extremities were analyzed. Local temperatures were assessed by comparing the mean temperature differences (ΔT) in 30 regions of interest (ROIs), and abnormal thermal patterns were divided into seven regions. To aid the diagnosis of radiculopathy, magnetic resonance imaging (MRI) and electrophysiological tests were also carried out. Results The incidence of disc herniation on MRI was 86%; 43% of patients showed electrophysiological abnormalities. On DITI, 97% of the patients showed abnormal ΔT in at least one of the 30 ROIs, and 79% showed hypothermia on the involved side. Seventy-eight percent of the patients also showed abnormal thermal patterns in at least one of the seven regions. Patients who had motor weakness or lateral-type disc herniation showed some correlations with abnormal DITI findings. However, neither pain severity nor other physical or electrophysiological findings were related to the DITI findings. Conclusion Skin temperature change following lumbosacral radiculopathy was related to some clinical and MRI findings, suggesting muscle atrophy. DITI, despite its limitations, might be useful as a complementary tool in the diagnosis of unilateral lumbosacral radiculopathy.

Annals of rehabilitation medicine, 2014

To delineate cervical radiculopathy that is found in combination with traumatic cervical spinal c... more To delineate cervical radiculopathy that is found in combination with traumatic cervical spinal cord injury (SCI) and to determine whether attendant cervical radiculopathy affects the prognosis and functional outcome for SCI patients. A total of 66 patients diagnosed with traumatic cervical SCI were selected for neurological assessment (using the International Standards for the Neurological Classification of Spinal Cord Injury [ISNCSCI]) and functional evaluation (based on the Korean version Modified Barthel Index [K-MBI] and Functional Independence Measure [FIM]) at admission and upon discharge. All of the subjects received a preliminary electrophysiological assessment, according to which they were divided into two groups as follows: those with cervical radiculopathy (the SCI/Rad group) and those without (the SCI group). A total of 32 patients with cervical SCI (48.5%) had cervical radiculopathy. The initial ISNCSCI scores for sensory and motor, K-MBI, and total FIM did not signifi...

PLoS ONE, 2013

Transcription factor-based reprogramming can lead to the successful switching of cell fates. We h... more Transcription factor-based reprogramming can lead to the successful switching of cell fates. We have recently reported that mouse embryonic fibroblasts (MEFs) can be directly reprogrammed into induced neural stem cells (iNSCs) after the forced expression of Brn4, Sox2, Klf4, and Myc. Here, we tested whether iNSCs could be further reprogrammed into induced pluripotent stem cells (iPSCs). The two factors Oct4 and Klf4 were sufficient to induce pluripotency in iNSCs. Immunocytochemistry and gene expression analysis showed that iNSC-derived iPSCs (iNdiPSCs) are similar to embryonic stem cells at the molecular level. In addition, iNdiPSCs could differentiate into cells of all three germ layers, both in vitro and in vivo, proving that iNdiPSCs are bona fide pluripotent cells. Furthermore, analysis of the global gene expression profile showed that iNdiPSCs, in contrast to iNSCs, do not retain any MEF transcriptional memory even at early passages after reprogramming. Overall, our results demonstrate that iNSCs can be reprogrammed to pluripotency and suggest that cell fate can be redirected numerous times. Importantly, our findings indicate that the induced pluripotent cell state may erase the donor-cell type epigenetic memory more efficiently than other induced somatic cell fates.

Journal of The Royal Society Interface, 2011

Three-dimensional gel matrices provide specialized microenvironments that mimic native tissues an... more Three-dimensional gel matrices provide specialized microenvironments that mimic native tissues and enable stem cells to grow and differentiate into specific cell types. Here, we show that collagen three-dimensional gel matrices prepared in combination with adhesive proteins, such as fibronectin (FN) and laminin (LN), provide significant cues to the differentiation into neuronal lineage of mesenchymal stem cells (MSCs) derived from rat bone marrow. When cultured within either a three-dimensional collagen gel alone or one containing either FN or LN, and free of nerve growth factor (NGF), the MSCs showed the development of numerous neurite outgrowths. These were, however, not readily observed in two-dimensional culture without the use of NGF. Immunofluorescence staining, western blot and fluorescence-activated cell sorting analyses demonstrated that a large population of cells was positive for NeuN and glial fibrillary acidic protein, which are specific to neuronal cells, when cultured...