Ki Young Kwon

Korea Advanced Institute of Science and Technology, Sŏul, Seoul, South Korea

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Publications (19)38.51 Total impact

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    ABSTRACT: A simple study using a fixed amount of mesoporous carbon (MSU-F-C) was performed for the comparison of pyranose oxidase (POx) and glucose oxidase (GOx) in their electrochemical performance under biosensor and biofuel cell operating modes. Even though the ratio of POx to GOx in the glucose oxidation activity per unit weight of MSU-F-C was 0.35, the ratios of POx to GOx in sensitivity and power density were reversed to be 6.2 and 1.4, respectively. POx with broad substrate specificity and an option of large scale production using recombinant E. coli has a great potential for various electrochemical applications, including biofuel cells.
    Electroanalysis 09/2014; · 2.82 Impact Factor
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    ABSTRACT: We investigated the clinical outcome of bone marrow (BM) involvement in patients with diffuse large B-cell lymphoma (DLBCL) who received rituximab-based therapy. A total of 567 consecutive patients with newly diagnosed DLBCL treated with rituximab-CHOP (RCHOP) between November 2001 and March 2010 were included in the current study. All of the patients underwent a BM study at the initial staging and the clinical characteristics and prognosis of these patients with or without BM involvement were analyzed retrospectively. The total cohort included 567 patients. The overall incidence of BM involvement was 8.5%. With a median follow-up duration of 33.2 months (range, 0.1 to 80.7 months) for patients who were alive at the last follow-up, the five-year overall survival (OS) and event-free survival (EFS) rate in patients without BM involvement (76.3% and 67.5%, p<0.001) was statistically higher than that in patients with BM involvement (44.3% and 40.1%, p<0.001). In multivariate analysis, among total patients, BM involvement showed a significant association with OS and EFS. In univariate and multivariate analyses, even among stage IV patients, a significant association with worse EFS was observed in the BM involvement group. BM involvement at diagnosis affected the survival of patients with DLBCL who received RCHOP. Although use of RCHOP can result in significant improvement of the therapeutic effect of DLBCL, BM involvement is still a negative prognostic factor of DLBCL patients in the era of rituximab.
    Cancer Research and Treatment 06/2013; 45(2):112-7. · 1.96 Impact Factor
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    ABSTRACT: Enzymatic biofuel cells (BFC) have a great potential as a small power source, but their practical applications are being hampered by short lifetime and low power density. This study describes the direct immobilization of glucose oxidase (GOx) onto the carbon paper in the form of highly stable and active enzyme precipitation coatings (EPCs), which can improve the lifetime and power density of BFCs. EPCs were fabricated directly onto the carbon paper via a three-step process: covalent attachment (CA), enzyme precipitation, and chemical crosslinking. GOx-immobilized carbon papers via the CA and EPC approaches were used as an enzyme anode and their electrochemical activities were tested under the BFC-operating mode. The BFCs with CA and EPC enzyme anodes produced the maximum power densities of 50 and 250 µW/cm(2) , respectively. The BFC with the EPC enzyme anode showed a stable current density output of >700 µA/cm(2) at 0.18 V under continuous operation for over 45 h. When a maple syrup was used as a fuel under ambient conditions, it also produced a stable current density of >10 µA/cm(2) at 0.18 V for over 25 h. It is anticipated that the direct immobilization of EPC on hierarchical-structured electrodes with a large surface area would further improve the power density of BFCs that can make their applications more feasible.
    Biotechnology and Bioengineering 08/2011; 109(2):318-24. · 4.16 Impact Factor
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    ABSTRACT: In this study, we directly immobilize glucose oxidase (GOx) onto the carbon paper using two different enzyme immobilization techniques: (1) Covalent Attachment (CA) and (2) Enzyme Precipitation and Crosslining (EPC). We use these carbon papers with immobilized GOx as the enzyme anode electrode for fabricating an airbreathing enzymatic biofuel cell (BFC). A total size of our biofuel cell is similar to a size of U.S. penny. Performances of biofuel cells are tested under the ambient operating conditions using 200 mM of glucose solution containing 10 mM benzoquinone (BQ). No buffer solutions are used for our study to mimic the real-world application. Under these operating conditions, our biofuel cell with CA and EPC enzyme anode electrodes can produce a maximum power density of 8.4 and 110 uW/cm2, respectively. From the constant voltage test of our biofuel cell with the EPC enzyme anode, it shows a stable current density output of > 700uA/cm2 at 0.18V over 45 hours. When the biofuel cell with the EPC enzyme anode operated with a real maple syrup under the ambient conditions, it produces a stable current density of >10 uA/cm2 at 0.18V over 25 hours.
    2010 AIChE Annual Meeting; 11/2010
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    ABSTRACT: Nanoscale enzyme reactors (NERs) of glucose oxidase in conductive mesoporous carbons were prepared in a two-step process of enzyme adsorption and follow-up enzyme crosslinking. MSU-F-C, a mesoprous carbon, has a bottleneck pore structure with mesocellular pores of 26 nm connected with window mesopores of 17 nm. This structure enables the ship-in-a-bottle mechanism of NERs, which effectively prevents the crosslinked enzymes in mesocellular pores from leaching through the smaller window mesopores. This NER approach not only stabilized the enzyme but also expedited electron transfer between the enzyme and the conductive MSU-F-C by maintaining a short distance between them. In a comparative study with GOx that was simply adsorbed without crosslinking, the NER approach was proven to be effective in improving the sensitivity of glucose biosensors and the power density of biofuel cells. The power density of biofuel cells could be further improved by manipulating several factors, such as by adding a mediator, changing the order of adsorption and crosslinking, and inserting a gold mesh as an electron collector.
    Biosensors & Bioelectronics 10/2010; 26(2):655-60. · 6.45 Impact Factor
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    ABSTRACT: We experienced a rare case of solitary syphilitic osteomyelitis of the skull without any other clinical signs or symptoms of syphilis. A 20-year-old man was referred due to intermittent headache and mild tenderness at the right parietal area of the skull with a palpable coin-sized lesion of softened cortical bone. On radiological studies, the lesion was a radiolucent well enhanced mass (17 mm in diameter). The erythrocyte sedimentation rate (52 mm/h) and C-reactive protein (2.24 mg/dL) were elevated on admission. Serum venereal disease research laboratory (VDRL) and Treponema pallidum haemagglutination assay (TPHA) tests were positive. There were no clinical signs or symptoms of syphilis. After treatment with benzathine penicillin, we removed the lesion and performed cranioplasty. The pathologic finding of the skull lesion was fibrous proliferation with lymphoplasmocytic infiltration forming an osteolytic lesion. In addition, a spirochete was identified using the Warthin-starry stain. The polymerase chain reaction study showed a positive band for Treponema pallidum. Solitary osteomyelitis of the skull can be the initial presenting pathological lesion of syphilis.
    Journal of Korean Neurosurgical Society 07/2010; 48(1):85-7. · 0.60 Impact Factor
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    ABSTRACT: Single-walled carbon nanotube (SWCNT) network films with high network density were prepared by vacuum-filtering a suspension of SWCNTs, and used as a host of enzyme precipitate coating of glucose oxidase (EPC-GOx). EPC-GOx was fabricated into the SWCNT network films in a two-step process of enzyme precipitation and crosslinking. High GOx loading in a form of EPC expedited the generation of electrons while the good connectivity of conductive SWCNTs in the network structure increased the electron transfer rate. According to amperometric measurements, the sensitivities of GOx/SWCNT electrodes, governed by both generation and transfer of electrons, were significantly enhanced by filling up the open pores of SWCNT films with the EPC-GOx when compared to the approaches of covalent-attachment (CA) and enzyme coating (EC) with no step of enzyme precipitation. For example, the sensitivities of CA, EC and EPC-GOx were 0.039, 0.140, and 5.72 μA mM−1, respectively. High sensitivity of EPC-GOx was maintained under iterative uses for 10 days. The deposition of gold nanoparticles into SWCNT films has resulted in high-performance glucose sensors with a remarkable sensitivity of 24.5 μA mM−1, which can be explained by further expedited electron transfer due to deposited gold nanoparticles.Graphical abstractResearch highlights► Highly porous SWCNT network film enables high enzyme loading. ► High network density of SWCNT film reduces the electron transfer resistance. ► Enzyme precipitate coating in SWCNT film achieves high glucose sensitivity. ► Gold nanoparticle deposition further enhances the sensitivity of enzyme electrode.
    Carbon. 01/2010; 48(15):4504-4509.
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    ABSTRACT: This study was conducted to investigate the correlation between the degrees of injury on brain magnetic resonance imaging (MRI) and the time interval to recovery of consciousness in patients with diffuse axonal injury. From January 2004 to December 2008, 25 patients with diffuse axonal injury were treated at our hospital. We retrospectively investigated the patients' medical records and radiological findings. We divided the patients into three groups according to the grade of MRI finding : grade I, small scattered lesions on the white matter of the cerebral hemisphere; grade II, focal lesions on the corpus callosum; and grade III, additional focal lesions on the brain stem. Seven patients belonged to the grade I group; 10 to the grade II group; and 8 to the grade III group. The mean Glasgow Coma Scale (GCS) score of all patients at the time of admission was 7.28. Recovery of consciousness was observed in 23 of the 25 patients; the remaining two patients never regained consciousness. The time interval to recovery of consciousness (awake status) ranged from 1 day to 125 days (mean 22.1 days) : grade I group patients, within approximately 1 week (mean 3.7 days); grade II group patients, within approximately 2 weeks (mean 12.5 days); and grade III group patients, within approximately 2 months (mean 59.5 days). Our study results suggest a correlation between the mean time interval to recovery of consciousness in patients with diffuse axonal injuries and the degrees of brain injuries seen on MRI. Patients with grade I and II diffuse axonal injuries recovered consciousness within 2 weeks, while patients with grade III injuries required approximately 2 months.
    Journal of Korean Neurosurgical Society 09/2009; 46(3):205-9. · 0.60 Impact Factor
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    ABSTRACT: Spontaneous spinal epidural hematoma (SSEH) is a relatively rare but significant spinal condition. Urgent surgical evacuation of a hematoma is generally indicated to prevent serious permanent neurological deficits. We encountered three cases of spontaneous spinal epidural hematomas associated with motor weakness that were treated successfully by surgical intervention.
    Journal of Korean Neurosurgical Society 08/2008; 44(1):40-2. · 0.56 Impact Factor
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    ABSTRACT: An irinotecan and cisplatin (IP) combination is one of active regimen used in treatment of extensive stage disease (ED) small cell lung cancer (SCLC). However, a 4-week cycle of irinotecan treatment can result in significant myelosuppression and diarrhea. Therefore, the present study was conducted to evaluate the efficacy and safety of biweekly IP in patients with ED SCLC. Patients with previously untreated ED SCLC received intravenous irinotecan at a dose of 60mg/m(2) and cisplatin at a dose of 30mg/m(2) on days 1 and 15 every 4 weeks. Thirty-five patients were enrolled in this study. Three complete responses and 23 partial responses were confirmed, giving an overall response rate of 74.3%. After a median follow-up of 15.1 months, the median time to progression and overall survival were 7.7 months and 12.2 months, respectively. Grade 3/4 neutropenia occurred in seven patients and grade 3 febrile neutropenia was observed in one patient. Grade 3 diarrhea occurred in two patients. The combination chemotherapy of biweekly IP was found to be well tolerated and effective in patients with ED SCLC. Further evaluation of the combination of IP at the dose and schedule in this study is warranted in ED SCLC patients.
    Lung Cancer 02/2008; 59(1):76-80. · 3.39 Impact Factor
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    ABSTRACT: No definitive recommendation is available concerning optimal antithrombotic therapy in pregnant women with a mechanical heart valve. The purpose of the current study was to evaluate the clinical results of nadroparin treatment with respect to pregnancy outcome and maternal complications. From 1997 to 2005, 31 pregnancies were reviewed in 25 women. Nadroparin (7,500 U, twice daily) was used in 23 pregnancies between 6 and 12 weeks of gestation and close-to-term only, and coumarin derivatives were used with aspirin at other times. Eight pregnant women treated with coumarin derivatives throughout pregnancy were compared to evaluate the safety and efficacy of nadroparin. No maternal death or bleeding complication occurred in either of the two groups, and frequencies of maternal thromboembolism including valve thrombosis (8.7% vs. 12.5%, p>0.05) were similar. However, the frequencies of live born (91.3% vs. 50%, p=0.01) and healthy babies (90.4% vs. 25%, p<0.01) were significantly higher, and the fetal loss rate was significantly lower (8.7% vs. 50%, p=0.01) in the nadroparin-treated group. Regarding the efficacy and safety of antithrombotic treatment in pregnant women with prosthetic heart valves, nadroparin treatment during the first trimester is an acceptable regimen and produces better results than coumarin derivatives.
    Journal of Korean Medical Science 04/2007; 22(2):258-61. · 1.25 Impact Factor
  • Small 09/2006; 2(8-9):1010-5. · 7.82 Impact Factor
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    ABSTRACT: Apoptosis pathways are known to be involved in the pathogenesis of peripheral T-cell lymphomas (PTCLs). As such, the current study attempted to investigate the overexpression of Bcl-2, Bax, or p53 with respect to the progression of PTCL. Paraffin-embedded specimens from 74 patients were analyzed immunohistochemically for Bcl-2, Bax, or p53 overexpression including PTCL-unspecified (n=45), extranodal natural killer cell/T-cell lymphoma (n=10), angioimmunoblastic T-cell lymphoma (n=7), anaplastic large cell lymphoma (n=7), and cutaneous T-cell lymphoma (n=5). The Bcl-2 overexpression was exhibited in 33 (45%), Bax, 17 (23%), and p53, 33 patients (45%). Bcl-2 overexpression was strongly associated with advanced stage (p=0.021) and higher international prognostic indices (IPI) (p=0.038). Bcl-2(+)/p53(+) group was found to be associated with advanced stage (p=0.008) and higher IPI (p=0.001), compared with the other groups. The independent expression of Bcl-2 or p53 was not correlated with survival. Meanwhile, when confined to Bcl-2 overexpressing groups, p53 overexpression was significantly associated with poor survival (p=0.05), as the 3-year OS rate was 82.5% for Bcl-2(+)/p53- cases, yet only 32.9% for Bcl-2(+)/p53(+) cases. Multivariate analyses for OS found the Bcl-2/p53 co-expression (p=0.004) as independent prognostic factor, together with advanced stage (p<0.001) and higher prognostic index for PTCL (p=0.008). Bcl-2 overexpression seemed to correlate with the progression of PTCL interacting with a p53-dependent pathway.
    Annals of Hematology 09/2006; 85(9):575-81. · 2.87 Impact Factor
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    ABSTRACT: The present study evaluated the expression and mutations of c-kit in peripheral T-cell lymphomas (PTCLs), except for extra-nodal NK/T cell lymphomas, as a potential target for treatment with imatinib mesylate. Fifty-two patients diagnosed with PTCLs (peripheral T-cell lymhoma, unspecified, 38 cases; angioimmunoblastic T-cell, 7 cases; anaplastic large cell, 7 cases) were enrolled. The immunohistochemistry was performed using standard procedures with anti-c-kit monoclonal IgG, while the c-kit mutations were analysed on paraffin-embedded specimens using PCR-single-stranded conformational polymorphism followed by direct DNA sequencing. The median age of the patients was 52 years (19 to approximately 75 years) with a male-to-female ratio of 69%:31%. Weak expression of c-kit was found in 16 (30.8%) patients, while only 3 (5.8%) patients exhibited mutations in exon 11 or exon 13. The c-kit mutations in exon 11 occurred at codon 558 (AAG --> TAG; Lys --> Stop) and at codon 571 (CTA --> ATA; Leu --> Ile), respectively, while the mutation in exon 13 occurred at codon 634 (CGG --> CGA; Arg --> Arg). The current study only found c-kit mutations in a few patients with PTCLs, except for extra-nodal NK/T cell lymphomas. Therefore, c-kit would not seem to be a good target for a new therapeutic approach to PTCLs.
    Leukemia and Lymphoma 02/2006; 47(2):267-70. · 2.61 Impact Factor
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    ABSTRACT: The current phase II study was conducted to evaluate the response rate and safety of a combination regimen of biweekly irinotecan plus cisplatin in pretreated patients with advanced gastric cancer. Patients with previously treated metastatic or recurrent gastric cancer received intravenous irinotecan 70 mg/m2 and cisplatin 30 mg/m2 on day 1 and 15 every 4-week cycle. Thirty-two patients were enrolled in the current study. Of these, 31 patients were assessable for efficacy and all for toxicity. No complete response and 5 partial responses were confirmed, giving an overall response rate of 15.6% (95% CI; 2.3-28.9%). The median time to progression and median overall survival for all patients was 113 days and 184 days, respectively. Grade 3/4 neutropenia occurred in 6 patients (18.8%), yet no febrile neutropenia was observed. In addition, grade 3 anorexia was observed in 4 patients (12.5%) and grade 3 diarrhea occurred in 2 patients (6.2%). The combination chemotherapy of biweekly irinotecan and cisplatin was found to be moderately effective and well tolerated in pretreated patients with advanced gastric cancer. Accordingly, this regimen can be regarded as an important second-line treatment option for advanced gastric cancer.
    Journal of Korean Medical Science 01/2006; 20(6):966-70. · 1.25 Impact Factor
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    ABSTRACT: Although many treatments for advanced gastric cancer have been developed, only poor treatment results have generally been obtained. We performed a prospective study on the combination chemotherapy of paclitaxel and cisplatin (PC). The primary objectives of the study were elucidating the disease response and evaluating the drug regimen's safety. Patients with metastatic or recurrent gastric cancer received intravenous paclitaxel 175 mg/m2, and cisplatin 70 mg/m2 on day 1. This cycle was repeated every 3 weeks. From January 2000 to March 2004, 37 patients from 3 different hospitals were enrolled in this study. A total of 135 treatment cycles (median: 3 cycles) were administered. The responses were evaluable in 34 patients; 24 patients received this regimen as their first-line treatment for metastatic cancer and the other patients received it as their second-line treatment for recurrent cancer. The objective response rate (RR) was 26.5% (95% CI: 11.7-41.3) with two complete responses, and stable disease was observed in 41.1% of the patients. Importantly, an RR of 33.3% (95% CI: 0.6-66.0) was achieved for the eight patients who received this regimen as a first-line treatment. The median follow up duration was 14 months for all the patients, and the median time to progression was 6 months (95% CI: 1.9-10.2). The overall survival time was 8.9 months (95% CI: 7.0-11.0) with a 1-year survival rate of 18.7% (95% CI: 5.6-31.8). The most common toxicity was neutropenia. PC exhibited promising activity against gastric cancer for the previously untreated patients as a first-line treatment with an acceptable toxicity profile.
    The Korean Journal of Internal Medicine 07/2005; 20(2):135-40.
  • The Korean journal of hematology 01/2005; 40(1).
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    ABSTRACT: Substantial pain is experienced by a lot of patients with cancer, and undertreated pain significantly undermines their quality of life. Despite international and national guidelines on cancer pain management, the practical effectiveness of management is still problematic. We did a prospective cross-sectional survey on pain prevalence, pain intensity, its impact on daily activity, and adequacy of pain management in 823 patients treated by medical oncologists and radiologic oncologists. At the time of the survey, 29.7% of the patients had pain that was moderate or severe. Performance status and tumor extent were significant predictors of pain presence and its intensity. Pain severity and the proportion of the patients whose function is impaired are highly associated. Among the patients with pain, only 37% rated pain relief as satisfactory. Forty-one percent of the patients with pain received inadequate pain management. Physicians did not adjust the analgesic prescription in about 53% of the patients who reported severe pain. These results demonstrate the alarming degree of undertreatment of pain in patients with cancer in Korea, and indicate the need to improve the management of cancer-related pain. Future research should elucidate the factors that impede adequate pain management in order to overcome obstacles to adequate treatment.
    Oncology 02/2003; 64(3):237-44. · 2.17 Impact Factor
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    ABSTRACT: S The single molecule approach is potentially of great technological interest as a complementary means to obtain information about protein conformation or molecular interaction. The measurement for molecular interaction in single molecule level requires that the molecule in the question is immobilized by binding to an appropriate surface. W have developed a novel fabrication method of nano-patterned array of bio-molecules with ultra-high density, using self-assembly of block-copolymers. Compared to previous lithographic methods, self-assembly of block-copolymers makes it easier to fabrication of patterns with ~ 10 nanometer feature size and to reduce the number of processing steps. In this work, we have detected a single molecule array on the basis of immunoreaction using protein conjugated gold nanoparticle. In this manner, BCP structure played an important role as confining molecules in single molecule level to a hole avoiding intermolecular interaction or nonspecific binding.