Publications by authors named "Kyu-Hwan Park"

33 Publications

Electrocardiographic Manifestations in Patients with COVID-19: Daegu in South Korea.

Korean Circ J 2021 Oct;51(10):851-862

Division of Cardiology, Daegu Catholic University College of Medicine, Daegu, Korea.

Background And Objectives: As the coronavirus disease 2019 (COVID-19) spreads worldwide, cardiac injury in patients infected with COVID-19 becomes a significant concern. Thus, this study investigates the impact of several electrocardiogram (ECG) parameters and disease severity in COVID-19 patients.

Methods: Seven medical centers in Daegu admitted 822 patients with COVID-19 between February and April 2020. This study examined 267 patients among them who underwent an ECG test and evaluated their biochemical parameters like C-reactive protein (CRP), log N-terminal pro-B-type Natriuretic Peptide (NT-proBNP), cardiac enzyme, and ECG parameters (heart rate, PR interval, QRS interval, T inversion, QT interval, and Tpe [the interval between peak to end in a T wave]).

Results: Those patients were divided into 3 groups of mild (100 patients), moderate (89 patients), and severe (78 patients) according to clinical severity score. The level of CRP, log NT-proBNP, and creatinine kinase-myocardial band were significantly increased in severe patients. Meanwhile, severe patients exhibited prolonged QT intervals (QTc) and Tpe (Tpe-c) compared to mild or moderate patients. Moreover, deceased patients (58; 21.7%) showed increased dispersion of QTc and Tpe-c compared with surviving patients (78.2±41.1 vs. 40.8±24.6 ms and 60.2±37.3 vs. 40.8±24.5 ms, both p<0.05, respectively). The QTc dispersion of more than 56.1 ms could predict the mortality in multivariate analysis (odd ratio, 11.55; 95% confidence interval, 3.746-42.306).

Conclusions: COVID-19 infections could involve cardiac injuries, especially cardiac repolarization abnormalities. A prolonged QTc dispersion could be an independent predictable factor of mortality.
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http://dx.doi.org/10.4070/kcj.2021.0116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8484995PMC
October 2021

Expanded Polystyrene Beads Coated with Intumescent Flame Retardant Material to Achieve Fire Safety Standards.

Polymers (Basel) 2021 Aug 10;13(16). Epub 2021 Aug 10.

School of Chemical Engineering, Chonnam National University, Gwangju 61186, Korea.

The compatibility and coating ratio between flame retardant materials and expanded polystyrene (EPS) foam is a major impediment to achieving satisfactory flame retardant performance. In this study, we prepared a water-based intumescent flame retardant system and methylene diphenyl diisocyanate (MDI)-coated expandable polystyrene microspheres by a simple coating approach. We investigated the compatibility, coating ratio, and fire performance of EPS- and MDI-coated EPS foam using a water-based intumescent flame retardant system. The microscopic study revealed that the water-based intumescent flame retardant materials were successfully incorporated with and without MDI-coated EPS microspheres. The cone calorimeter tests (CCTs) of the MDI-coated EPS containing water-based intumescent flame retardant materials exhibited better flame retardant performance with a lower total heat release (THR) 7.3 MJ/m, peak heat release rate (PHRR) 57.6 kW/m, fire growth rate (FIGRA) 2027.067 W/ms, and total smoke production (TSP) 0.133 m. Our results demonstrated that the MDI-coated EPS containing water-based intumescent flame retardant materials achieved flame retarding properties as per fire safety standards.
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http://dx.doi.org/10.3390/polym13162662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8398555PMC
August 2021

Compression Molding of Thermoplastic Polyurethane Foam Sheets with Beads Expanded by Supercritical CO Foaming.

Polymers (Basel) 2021 Feb 22;13(4). Epub 2021 Feb 22.

Department of Polymer Science and Engineering, Dankook University, 152 Jukjeon-ro, Suji-gu, Yongin-si, Gyeonggi-do 16889, Korea.

Expanded thermoplastic polyurethane (ETPU) beads were prepared by a supercritical CO foaming process and compression molded to manufacture foam sheets. The effect of the cell structure of the foamed beads on the properties of the foam sheets was studied. Higher foaming pressure resulted in a greater number of cells and thus, smaller cell size, while increasing the foaming temperature at a fixed pressure lowered the viscosity to result in fewer cells and a larger cell size, increasing the expansion ratio of the ETPU. Although the processing window in which the cell structure of the ETPU beads can be maintained was very limited compared to that of steam chest molding, compression molding of ETPU beads to produce foam sheets was possible by controlling the compression pressure and temperature to obtain sintering of the bead surfaces. Properties of the foam sheets are influenced by the expansion ratio of the beads and the increase in the expansion ratio increased the foam resilience, decreased the hardness, and increased the tensile strength and elongation at break.
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http://dx.doi.org/10.3390/polym13040656DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7926550PMC
February 2021

Late complication of the Nuss procedure: recurrent cardiac tamponade.

Yeungnam Univ J Med 2019 09 13;36(3):260-264. Epub 2019 Jun 13.

Department of Emergency Medicine, Yeungnam University Medical Center, Daegu, Korea.

Pectus excavatum (PE) is known as one of the most common congenital deformities of the anterior chest wall. The Nuss procedure is an effective surgical therapy to correct PE. Here, we report a case of recurrent cardiac tamponade due to hemopericardium that occurred after 16 months following the Nuss procedure. The cause of recurrent hemopericardium was thought to be local, repetitive irritation of the pericardium by the Nuss steel bar. We should keep in mind that this serious complication can occur after the Nuss procedure, even in the late phase.
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http://dx.doi.org/10.12701/yujm.2019.00241DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6784654PMC
September 2019

Self-assembly kinetics of debranched short-chain glucans from waxy maize starch to form spherical microparticles and its applications.

Colloids Surf B Biointerfaces 2019 Apr 8;176:352-359. Epub 2019 Jan 8.

Institute of Life Sciences and Resources & Department of Food Science and Biotechnology, College of Life Sciences, Kyung Hee University, Yongin, 17104, South Korea. Electronic address:

Starch microparticles (SMPs) of well-defined size and morphology were synthesized through pullulanase-mediated debranching of waxy maize starch followed by spontaneous re-assembly of the resulting short-chain glucan molecules in aqueous solution. Enzymatic debranching of amylopectins from native starch generated two major fractions corresponding to a smaller glucan and partially digested larger amylopectin molecules. The ratio of short-chain glucan (SCG) over partially digested amylopectin (PDAp) turned out to be the deterministic factors for the size and crystallinity of SMPs, of which the ratio could be controlled by the concentration of debranching enzyme. The PDAp fraction was closely associated with the creation of nuclei, determining the growth kinetics of SMPs which led to the formation of SMPs with a diameter ranging from 0.52.5 μm. In addition, we demonstrated that iron oxide nanoparticles (IONPs) were successfully incorporated into the starch microstructure by introducing them during the self-assembly reaction, conferring desired functionality onto the final SMPs. The incorporated IONPs rendered the SMPs an excellent magnetic sensitivity, which were successfully applied for the separation and concentration of target bacteria upon conjugation of specific antibody on the surface of SMPs. The simple processes and biocompatible nature of starch would make this approach attractive for many applications in the area of food, medicine and other related materials sciences.
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http://dx.doi.org/10.1016/j.colsurfb.2019.01.002DOI Listing
April 2019

Corrigendum: Hemorheologic Alterations in Patients with Type 2 Diabetes Mellitus Presented with an Acute Myocardial Infarction.

Diabetes Metab J 2018 06;42(3):254

Department of Clinical Pathology, School of Medicine, Kyungpook National University, Daegu, Korea.

This corrects the article on p. 155 in vol. 42, PMID: 29676545.
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http://dx.doi.org/10.4093/dmj.2018.0096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6015959PMC
June 2018

Hemorheologic Alterations in Patients with Type 2 Diabetes Mellitus Presented with an Acute Myocardial Infarction.

Diabetes Metab J 2018 Apr;42(2):155-163

Department of Chemical Pathology, Kyungpook National University Hospital, Kyungpook National University School of Medicine, Daegu, Korea.

Background: Hemorheologic indices are known to be related to vascular complications in variable clinical settings. However, little is known about the associations between hemorheologic parameters and acute myocardial infarction (AMI) in type 2 diabetes mellitus (T2DM). The purpose of this study was to demonstrate the changes of hemorheologic environment inside of blood using hemorheologic parameters, especially the elongation index (EI) and critical shear stress (CSS) in diabetics with versus without AMI.

Methods: A total of 195 patients with T2DM were enrolled. Patients were divided into the study group with AMI (AMI+, n=77) and control group (AMI-, n=118) who had no history of coronary artery disease. Hemorheologic parameters such as EI and CSS were measured and compared between the two groups.

Results: The EI was lower (30.44%±1.77% in AMI+ and 31.47%±1.48% in AMI-, P<0.001) but the level of CSS was higher (316.13±108.20 mPa in AMI+ and 286.80±85.34 mPa in AMI-, P=0.040) in the AMI+. The CSS was significantly related to the erythrocyte sedimentation rate (R²=0.497, P<0.001) and use of dipeptidyl peptidase-4 inhibitors (R²=0.574, P=0.048).

Conclusion: Diabetics with AMI resulted in adverse hemorheologic changes with lower EI and higher CSS compared to diabetic subjects without AMI. Evaluation of the hemorheologic parameters may provide valuable supplementary information for managing patients with AMI and T2DM.
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http://dx.doi.org/10.4093/dmj.2018.42.2.155DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5911519PMC
April 2018

Microbial Biosynthesis of Silver Nanoparticles in Different Culture Media.

J Agric Food Chem 2018 Jan 22;66(4):957-962. Epub 2018 Jan 22.

Graduate School of Biotechnology and Department of Food Science and Biotechnology, College of Life Sciences, Kyung Hee University , Yongin 17104, Korea.

Microbial biosynthesis of metal nanoparticles has been extensively studied for the applications in biomedical sciences and engineering. However, the mechanism for their synthesis through microorganism is not completely understood. In this study, several culture media were investigated for their roles in the microbial biosynthesis of silver nanoparticles (AgNPs). The size and morphology of the synthesized AgNPs were analyzed by UV-vis spectroscopy, Fourier-transform-infrared (FT-IR), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The results demonstrated that nutrient broth (NB) and Mueller-Hinton broth (MHB) among tested media effectively reduced silver ions to form AgNPs with different particle size and shape. Although the involved microorganism enhanced the reduction of silver ions, the size and shape of the particles were shown to mainly depend on the culture media. Our findings suggest that the growth media of bacterial culture play an important role in the synthesis of metallic nanoparticles with regard to their size and shape. We believe our findings would provide useful information for further exploration of microbial biosynthesis of AgNPs and their biomedical applications.
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http://dx.doi.org/10.1021/acs.jafc.7b05092DOI Listing
January 2018

Discordant Relationships between Systemic Inflammatory Markers and Burden of Oxidative Stress in Patients with Atrial Fibrillation.

Korean Circ J 2017 Sep 14;47(5):752-761. Epub 2017 Aug 14.

Division of Cardiology, Department of Internal Medicine, Yeungnam University Medical Center, Daegu, Korea.

Background And Objectives: Oxidative stress (OS) plays an important role in the pathophysiology of atrial fibrillation (AF) by amplifying the inflammatory cascade, wherein augmented inflammation facilitates the atrial electrical remodeling process. Few studies have investigated the possible link between systemic inflammation and OS in AF.

Subjects And Methods: A total of 220 consecutive patients with AF (117 patients) or healthy controls (103 patients) were enrolled. Among the 117 AF patients, 65 paroxysmal AF (PaAF) and 52 persistent AF (PeAF) patients were included. The level of 8-iso-prostaglandin F2α (8-iso-PGF2α) was measured as a marker of OS burden. We evaluated the correlations between 3 systemic inflammatory markers, high-sensitivity C-reactive protein (hsCRP), neutrophil to lymphocyte ratio (NLR), and red cell distribution width (RDW), and 8-iso-PGF2α.

Results: The 8-iso-PGF2α concentration in both PaAF and PeAF patients was higher than that of controls (p<0.001 and p=0.024, respectively). The NLR and RDW of PeAF patients were higher than those of both control and PaAF patients (p=0.041 and p=0.031 for NLR, p=0.057 and p=0.031 for RDW, respectively). There were no correlations between specific inflammatory markers and the 8-iso-PGF2α in AF. The 8-iso-PGF2α level decreased gradually with an increase in AF duration (p=0.008), contrary to the graded increase in hsCRP. Multiple regression analysis indicated that AF duration persisted as a significant determinant of 8-iso-PGF2α (β=-0.249, p=0.044).

Conclusion: Systemic inflammatory marker levels were not proportional to the levels of 8-iso-PGF2α, an OS marker, in AF.
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http://dx.doi.org/10.4070/kcj.2017.0024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5614951PMC
September 2017

Migration of Large Thrombus From the Left Atrial Appendage During Transesophageal Echocardiography in a Stroke Patient.

Circ J 2017 12 8;82(1):297-298. Epub 2017 Jun 8.

Division of Cardiology, Department of Internal Medicine, Yeungnam University Medical Center.

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http://dx.doi.org/10.1253/circj.CJ-16-1301DOI Listing
December 2017

Effectiveness of Implantable Cardioverter-Defibrillator Therapy for Heart Failure Patients according to Ischemic or Non-Ischemic Etiology in Korea.

Korean Circ J 2017 Jan 27;47(1):72-81. Epub 2016 Dec 27.

Division of Cardiology, Department of Internal Medicine, Yeungnam University Medical Center, Daegu, Korea.

Background And Objectives: This study was performed to describe clinical characteristics of patients with left ventriculars (LV) dysfunction and implantable cardioverter-defibrillator (ICD), and to evaluate the effect of ICD therapy on survival in Yeongnam province of Korea.

Subjects And Methods: From a community-based device registry (9 centers, Yeongnam province, from November 1999 to September 2012), 146 patients with LV dysfunction and an ICD implanted for primary or secondary prophylaxis, were analyzed. The patients were divided into two groups, based on the etiology (73 with ischemic cardiomyopathy and 73 with non-ischemic cardiomyopathy), and indication for the device implantation (36 for primary prevention and 110 for secondary prevention). The cumulative first shock rate, all cause death, and type and mode of death, were determined according to the etiology and indication.

Results: Over a mean follow-up of 3.5 years, the overall ICD shock rate was about 39.0%. ICD shock therapy was significantly more frequent in the secondary prevention group (46.4% vs. 16.7%, p=0.002). The cumulative probability of a first appropriate shock was higher in the secondary prevention group (p=0.015). There was no significant difference in the all-cause death, cardiac death, and mode of death between the groups according to the etiology and indication.

Conclusion: Studies from this multicenter regional registry data shows that in both ischemic and non-ischemic cardiomyopathy patients, the ICD shock therapy rate was higher in the secondary prevention group than primary prevention group.
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http://dx.doi.org/10.4070/kcj.2016.0242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5287190PMC
January 2017

Effect of short-chain fatty acids on the formation of amylose microparticles by amylosucrase.

Carbohydr Polym 2016 Oct 3;151:606-613. Epub 2016 Jun 3.

Graduate School of Biotechnology & Department of Food Science and Biotechnology, College of Life Sciences, Kyung Hee University, Yongin, Republic of Korea. Electronic address:

Amylose microparticles can be produced by self-assembly of amylose molecules through an amylosucrase-mediated synthesis. Here we investigated the role of short-chain fatty acids in the formation of amylose microparticles and the fate of these fatty acids at the end of the reaction. The rate of self-assembly and production yields of amylose microparticles were significantly enhanced in the presence of fatty acids. The effect was dependent on the length of the fatty acid carbon tail; butanoic acid (C4) was the most effective, followed by hexanoic acid (C6) and octanoic acid (C8). The amylose microparticles were investigated by carrying out SEM, XRD, Raman, NMR, FT-IR and DSC analysis. The size, morphology and crystal structure of the resulting amylose microparticles were comparable with those of amylose microparticles produced without fatty acids. The results indicated the carboxyl group of the fatty acid to be responsible for promoting the self-assembly of amylose chains to form microparticles. The fatty acids were eventually removed from the microstructure through the tight association of amylose double helices to form the amylose microparticles.
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http://dx.doi.org/10.1016/j.carbpol.2016.05.105DOI Listing
October 2016

Stent Graft Using Kilt Technique for an Abdominal Aortic Aneurysm with a Severely Angulated Neck.

Heart Lung Circ 2016 Mar;25(3):e48-52

Endovascular aneurysm repair has become a standard treatment for abdominal aortic aneurysm (AAA). However a severely angulated aneurysmal neck is one of the most common anatomical limitations of endovascular repair, and is associated with poor outcomes. We successfully treated a patient who had an abdominal aortic aneurysm with a severely angulated aortic neck using kilt technique with thoracic stent graft. The technique might be an excellent alternative strategy to overcome anatomical obstacles like a hostile aortic neck.
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http://dx.doi.org/10.1016/j.hlc.2015.08.020DOI Listing
March 2016

Five-year clinical outcomes of drug-eluting stents according to on-label and off-label use.

Korean J Intern Med 2016 Jul 25;31(4):678-84. Epub 2016 Mar 25.

Division of Cardiology, Department of Internal Medicine, Daegu Veterans Hospital, Daegu, Korea.

Background/aims: To compare the clinical outcomes of 'on-label' and 'off-label' drug-eluting stents (DESs) over a 5-year follow-up period.

Methods: A total of 929 patients that underwent percutaneous coronary intervention with DESs were enrolled. Patients were divided into two groups according to on-label (n = 449) and off-label (n = 480) indications. Off-label use was defined as implantation of DESs for acute myocardial infarction (MI), very small vessel, a long stenotic lesion, chronic total occlusion, a bifurcation lesion, an ostial lesion, left main coronary artery disease, multivessel disease, a saphenous vein graft lesion, and a lesion with thrombus. Endpoints were composite of major adverse cardiac events (MACEs), which included all-cause death, ischemic-driven target vessel revascularization (Id-TVR), MI, and stent thrombosis (ST). Clinical outcomes in the two groups were compared for up to 5 years postimplantation.

Results: At 1 year postimplantation, the off-label group had higher incidences of total MACEs (8.2% vs. 3.7%, p = 0.005), Id-TVR (5.0% vs. 1.6%, p = 0.004), and ST (1.7% vs. 0.3%, p = 0.042), and at 5 years postimplantation, the off-label group continued to have higher incidences of total MACEs (17.5% vs. 9.4%, p < 0.001), Id-TVR (13.1% vs. 5.8%, p = 0.024), and ST (2.1% vs. 0.3%, p = 0.021). Multivessel disease and diabetes were found to be independent risk factors of MACE in patients with an off-label indication.

Conclusions: Patients treated with an on-label DES had better long-term clinical outcomes than those treated with an off-label DES.
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http://dx.doi.org/10.3904/kjim.2015.045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939495PMC
July 2016

Increased variability of the coupling interval of premature ventricular contractions as a predictor of cardiac mortality in patients with left ventricular dysfunction.

Circ J 2015 10;79(11):2360-6. Epub 2015 Sep 10.

Cardiovascular Division, College of Medicine, Yeungnam University Medical Center.

Background: The characteristics and prognostic value of the variability of premature ventricular contraction (PVC) coupling intervals (CIs) for cardiac mortality are not yet decisive.

Methods and results: In 133 consecutive patients (58±14 years old, 53 women) who had left ventricular dysfunction (LVD: ejection fraction <50%) and frequent PVCs (≥10/h) who underwent 24-h ambulatory electrocardiography (AECG) recording and (123)I-metaiodobenzylguanidine myocardial single-photon emission computed tomography simultaneously, the heart rate turbulence onset, slope, and T-wave alternans were analyzed from the 24-h AECG. The CI of the PVCs (MEANNV), standard deviation of the CI of the PVCs (SDNV) as an index of the variability of the PVC CI, and their ratio to the preceding N-N intervals (SDNV/SDNN) were calculated from constructed Poincaré plots using the annotated 24-h AECG QRS data. The primary endpoint was cardiac mortality. The mean follow-up period was 63 months. Among 133 patients, 114 survived (group 1) and 19 (14%, group 2) died during the follow-up. The MEANNVand SDNVwere higher in group 2 (539±104 vs. 599±114 ms, P=0.021; 64±34 vs. 83±37 ms, P=0.022, respectively). The SDNV, PVC count, and delayed heart/mediastinum ratio remained as significant predictors of cardiac mortality in the binary logistic regression analysis.

Conclusions: These results suggest that the SDNVcould be another adjunctive parameter for predicting cardiac mortality in LVD.
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http://dx.doi.org/10.1253/circj.CJ-15-0732DOI Listing
August 2016

"Optimal" cutoff value of heart rate; appraisal based on heart rate variability and C-reactive protein.

Int J Cardiol 2014 Sep 12;176(2):497-9. Epub 2014 Jul 12.

Cardiovascular Division, Internal Medicine, Yeungnam University Hospital, Daegu 705-717, South Korea. Electronic address:

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http://dx.doi.org/10.1016/j.ijcard.2014.07.061DOI Listing
September 2014

Metabolic changes in serum steroids induced by total-body irradiation of female C57B/6 mice.

J Steroid Biochem Mol Biol 2014 May 21;141:52-9. Epub 2014 Jan 21.

Future Convergence Research Division, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea. Electronic address:

The short- and long-term effects of a single exposure to gamma radiation on steroid metabolism were investigated in mice. Gas chromatography-mass spectrometry was used to generate quantitative profiles of serum steroid levels in mice that had undergone total-body irradiation (TBI) at doses of 0Gy, 1Gy, and 4Gy. Following TBI, serum samples were collected at the pre-dose time point and 1, 3, 6, and 9 months after TBI. Serum levels of progestins, progesterone, 5β-DHP, 5α-DHP, and 20α-DHP showed a significant down-regulation following short-term exposure to 4Gy, with the exception of 20α-DHP, which was significantly decreased at each of the time points measured. The corticosteroids 5α-THDOC and 5α-DHB were significantly elevated at each of the time points measured after exposure to either 1 or 4Gy. Among the sterols, 24S-OH-cholestoerol showed a dose-related elevation after irradiation that reached significance in the high dose group at the 6- and 9-month time points.
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http://dx.doi.org/10.1016/j.jsbmb.2014.01.004DOI Listing
May 2014

One-pot synthesis of trimetallic [email protected] core-shell nanoparticles with high catalytic performance.

ACS Nano 2013 Sep 8;7(9):7945-55. Epub 2013 Aug 8.

Department of Chemistry and KI for the NanoCentury, KAIST , Daejeon 305-701, Korea, and Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701, Korea.

The development of an efficient synthesis method to produce multimetallic nanoparticles (NPs) with a desirable structure is strongly required to clarify the structure-composition-property relationship of NPs and to investigate their possible applications. However, the controlled synthesis of NPs consisting of multiple (n ≥ 3) noble metal components has been relatively unexplored in comparison to bimetallic NPs. In the present work, we have demonstrated a facile one-pot aqueous approach for the controlled synthesis of trimetallic [email protected] core-shell NPs with a well-defined octahedral Au core and a highly crystalline dendritic Pd-Pt alloy shell ([email protected] NPs). The simultaneous reduction of multiple metal precursors with dual reducing agents, namely, ascorbic acid and hydrazine, gave a fine control over the nucleation and growth kinetics of NPs, resulting in the formation of novel [email protected] NPs. The prepared NPs showed excellent catalytic performance for methanol electrooxidation, which can be attributed to their optimized binding strength toward adsorbate molecules due to the improved charge transfer between core and shell of the NPs. The present strategy can offer a convenient and valuable way to fabricate multicomponent nanostructures with desired structures and functions.
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http://dx.doi.org/10.1021/nn403027jDOI Listing
September 2013

Simultaneous molecular formula determinations of natural compounds in a plant extract using 15 T Fourier transform ion cyclotron resonance mass spectrometry.

Plant Methods 2013 30;9:15. Epub 2013 May 30.

Division of Mass Spectrometry Research, Korea Basic Science Institute, Ochang, Chungcheongbuk-Do 363-883, South Korea.

Background: Plant extracts are a reservoir of pharmacologically active substances; however, conventional analytical methods can analyze only a small portion of an extract. Here, we report a high-throughput analytical method capable of determining most phytochemicals in a plant extract and of providing their molecular formulae from a single experiment using ultra-high-resolution electrospray ionization mass spectrometry (UHR ESI MS). UHR mass profiling was used to analyze natural compounds in a 70% ethanol ginseng extract, which was directly infused into a 15 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer for less than 10 min without a separation process.

Results: The UHR FT-ICR MS yielded a mass accuracy of 0.5 ppm and a mass resolving power (m/Δm) of 1,000,000-270,000 for the range m/z 290-1,100. The mass resolution was sufficient to resolve the isotopic fine structure (IFS) of many compounds in the extract. After noise removal from 1,552 peaks, 405 compounds were detected. The molecular formulae of 123 compounds, including 33 ginsenosides, were determined using the observed IFS, exact monoisotopic mass, and exact mass difference. Liquid chromatography (LC)/FT-ICR MS of the extract was performed to compare the high-throughput performance of UHR ESI FT-ICR MS. The LC/FT-ICR MS detected only 129 compounds, including 19 ginsenosides. The result showed that UHR ESI FT-ICR MS identified three times more compounds than LC/FT-ICR MS and in a relatively shorter time. The molecular formula determination by UHR FT-ICR MS was validated by LC and tandem MS analyses of three known ginsenosides.

Conclusions: UHR mass profiling of a plant extract by 15 T FT-ICR MS showed that multiple compounds were simultaneously detected and their molecular formulae were decisively determined by a single experiment with ultra-high mass resolution and mass accuracy. Simultaneous molecular determination of multiple natural products by UHR ESI FT-ICR MS would be a powerful method to profile a wide range of natural compounds.
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http://dx.doi.org/10.1186/1746-4811-9-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3706383PMC
May 2014

One-pot synthesis of CeO₂-supported Pd-Cu-alloy nanocubes with high catalytic activity.

Chemistry 2013 Jun 10;19(25):8053-7. Epub 2013 May 10.

Department of Chemistry and KI for the NanoCentury, KAIST, Daejeon, 305-701, Korea.

Cerium and nanocubes: CeO₂-supported Pd-Cu-alloy nanocubes (Pd-Cu NCs/CeO₂) with high content and good dispersion of the Pd-Cu NCs were prepared in high yields by heating a solution containing Pd, Cu, and Ce precursors. The prepared Pd-Cu NCs/CeO₂ have excellent catalytic activity and stability toward formic acid electro-oxidation due to the synergism between the Pd-Cu-alloy catalysts and the CeO₂ support.
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http://dx.doi.org/10.1002/chem.201301188DOI Listing
June 2013

Clarification of a peak at m/z 1634 from tryptically digested cytochrome c.

J Mass Spectrom 2012 Dec;47(12):1576-81

A peptide peak at m/z 1634 in the mass spectrum of tryptically digested cytochrome c has been ambiguously assigned to either a peptide IFVQKCAQCHTVEK or a peptide CAQCHTVEK combined with a heme group (CAQCHTVEK + heme (Fe(III))). A comprehensive investigation was performed to clearly identify the origin of the peak. Tryptic digests of cytochrome c were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), liquid chromatography-tandem MS (LC-MS/MS), LC-ultraviolet (LC-UV), and MALDI Fourier transform-ion cyclotron resonance (FT-ICR) MS. The use of instruments with extremely high mass accuracy revealed the mass difference between the IFVQKCAQCHTVEK and the (CAQCHTVEK + heme (Fe(III))) ions. Fragmentation of the peptide associated with the unknown peak yielded a heme ion and other fragment ions originating from a (CAQCHTVEK + heme (Fe(III))) ion. Furthermore, an absorption peak at 395 nm confirmed the presence of a heme group in the unknown peptide. High mass accuracy analyses of MS and MS/MS spectra, in addition to three-dimensional UV contour mapping, showed that the peak at m/z 1634 is due to a (CAQCHTVEK + heme (Fe(III))) ion and not from protonated IFVQKCAQCHTVEK.
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http://dx.doi.org/10.1002/jms.3119DOI Listing
December 2012

Characterization of the left atrial vortex flow by two-dimensional transesophageal contrast echocardiography using particle image velocimetry.

Ultrasound Med Biol 2013 Jan 15;39(1):62-71. Epub 2012 Oct 15.

Division of Cardiology, Yeungnam University, Daegu, Korea.

This article is the first clinical investigation of the quantitative left atrial (LA) vortex flow by two-dimensional (2-D) transesophageal contrast echocardiography (2-D-TECE) using vector particle image velocimetry (PIV). The aims of this study were to assess the feasibility of LA vortex flow analysis and to characterize and quantify the LA vortex flow in controls and in patients with atrial fibrillation (AF). Thirty-five controls and 30 patients with AF underwent transesophageal contrast echocardiography. The velocity vector was estimated by particle image velocimetry. The morphology and pulsatility of the LA vortex flow were compared between the control and AF groups. In all patients, quantitative LA vortex flow analysis was feasible. In the control group, multiple, pulsatile, compact and elliptical-shaped vortices were seen in the periphery of the LA. These vortices were persistently maintained and vectors were directed toward the atrioventricular inflow. In the AF group, a large, merged, lower pulsatile and round-shaped vortex was observed in the center of the LA. In comparisons of vortex parameters, the relative strength was significantly lower in the AF group (1.624 ± 0.501 vs. 2.105 ± 0.226, p < 0.001). It is feasible to characterize and quantify the LA vortex flow by transesophageal contrast echocardiography in patients with AF, which offers a new method to obtain additional information on LA hemodynamics. The approach has the potential for early detection of the LA dysfunction and in decisions regarding treatment strategy and guiding anticoagulation treatment in patients with AF.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2012.08.013DOI Listing
January 2013

One-pot synthesis of monodisperse 5 nm Pd-Ni nanoalloys for electrocatalytic ethanol oxidation.

ACS Appl Mater Interfaces 2012 Aug 25;4(8):4208-14. Epub 2012 Jul 25.

Department of Chemistry and KI for the NanoCentury, KAIST, Daejeon 305-701, Korea.

Highly monodisperse 5 nm Pd-Ni alloy nanoparticles (NPs) were prepared by the reduction of Pd(acac)(2)/Ni(acac)(2) mixtures with tert-butylamine-borane complex (TBAB) in the presence of oleic acid (OA) and oleylamine (OAm). Employing TBAB as an effective reductant and OA/OAm combination as an effective stabilizing agent is crucial to the formation of monodisperse Pd-Ni NPs. Experimental results collectively verify that the Pd-Ni alloy NPs form through the sequential nucleation-interdiffusion process and the simultaneous reduction of both metal precursors by the one-pot protocol is the key to the formation of homogeneous NPs. The Pd-Ni NPs were well-dispersed on carbon supports and chemically dealloyed after acetic acid washing through the selective dissolution of the less noble Ni component. The Pd-Ni NP catalysts exhibited much higher electrocatalytic activity and stability for ethanol oxidation than those of a commercial Pd/C catalyst.
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http://dx.doi.org/10.1021/am300923sDOI Listing
August 2012

Synthesis and photocatalytic properties of Cu2S-Pd4S hybrid nanoplates.

Chemistry 2012 May 29;18(19):5874-8. Epub 2012 Mar 29.

Department of Chemistry and KI for the NanoCentury, KAIST, Daejeon, 305-701, Korea.

Hex appeal! Cu(2)S-Pd(4)S hybrid nanocrystals with a novel hexagonal nanoplate structure were prepared in high yield by a simple one-pot synthetic method (see figure). Successful synthesis of this unique structure was achieved through a consecutive thermolysis process. The Cu(2)S-Pd(4)S hybrid nanoplates exhibited substantially higher photocatalytic activities than pure Cu(2)S nanoplates.
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http://dx.doi.org/10.1002/chem.201200025DOI Listing
May 2012

Analysis of cancer cell lipids using matrix-assisted laser desorption/ionization 15-T Fourier transform ion cyclotron resonance mass spectrometry.

Rapid Commun Mass Spectrom 2012 Mar;26(6):621-30

Department of Chemistry, Chungnam National University, Daejeon, Republic of Korea.

A combination of methodologies using the extremely high mass accuracy and resolution of 15-T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) was introduced for the identification of intact cancer cell phospholipids. Lipids from a malignant glioma cell line were initially analyzed at a resolution of >200,000 and identified by setting the mass tolerance to ±1 mDa using matrix-assisted laser desorption/ionization (MALDI) 15-T FT-ICR MS in positive ion mode. In most cases, a database search of potential lipid candidates using the exact masses of the lipids yielded only one possible chemical composition. Extremely high mass accuracy (<0.1 ppm) was then attained by using previously identified lipids as internal standards. This, combined with an extremely high resolution (>800,000), yielded well-resolved isotopic fine structures allowing for the identification of lipids by MALDI 15-T FT-ICR MS without using tandem mass spectrometric (MS/MS) analysis. Using this method, a total of 38 unique lipids were successfully identified.
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http://dx.doi.org/10.1002/rcm.6140DOI Listing
March 2012

Aneurysm of sinus of valsalva dissecting into the interventricular septum after aortic valve replacement: diagnosis by echocardiography and magnetic resonance imaging and treatment with surgical sealant.

Korean Circ J 2011 Aug 31;41(8):464-8. Epub 2011 Aug 31.

Division of Cardiology, Department of Internal Medicine, College of Medicine, Yeungnam University, Daegu, Korea.

Aneurysm of the sinus of Valsalva that causes dissection of the interventricular septum is an extremely rare entity. In this report we describe a case of aneurysm of the sinus of Valsalva dissecting into the interventricular septum, from the base to mid septum, after aortic valve replacement. After the diagnosis was made by transthoracic echocardiography and magnetic resonance imaging, the patient was successfully treated with surgical sealant-mediated occlusion of the aneurysmal sac and cardiac resynchronization therapy used for the first time.
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http://dx.doi.org/10.4070/kcj.2011.41.8.464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3173667PMC
August 2011

A facile one-pot synthesis and enhanced formic acid oxidation of monodisperse Pd-Cu nanocatalysts.

Chem Asian J 2011 Jun 20;6(6):1515-9. Epub 2011 Apr 20.

Department of Chemistry and KI for the NanoCentury, KAIST, Daejeon 305-701, Korea.

Highly monodisperse spherical 3 nm Pd-Cu alloy nanoparticles (NPs) were synthesized in high yield through the coreduction of [Pd(acac)(2)] (acac=acetylacetonate) and [Cu(acac)(2)] in nonhydrolytic solutions by using trioctylamine and oleic acid. The relative compositions of Pd and Cu could be tuned by controlling the molar ratios between the metal precursors in the raw solutions. The carbon-supported Pd-Cu NPs (Pd-Cu/C) were chemically dealloyed by acetic acid washing, which resulted in the formation of porous structures. The prepared Pd-Cu/C catalysts exhibited at least threefold enhancement of Pd mass activities compared with a commercial Pd/C catalyst toward formic acid oxidation in an acidic medium, and also showed outstanding electrocatalytic stabilities. The improved electrocatalytic properties of the Pd-Cu NPs are attributed to the presence of a large number of active sites on their surfaces owing to their small particle sizes and chemically dealloyed porous structures.
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http://dx.doi.org/10.1002/asia.201000808DOI Listing
June 2011

Massive left atrial calcification associated with mitral valve replacement.

J Cardiovasc Ultrasound 2010 Dec 31;18(4):151-3. Epub 2010 Dec 31.

Division of Cardiology, Department of Internal Medicine, College of Medicine, Yeungnam University, Daegu, Korea.

Calcification of the left atrium can be observed in patients with a long-lasting rheumatic heart disease. However, massive calcification of the atrial wall, so called porcelain or coconut atrium is very rare and has been generally reported only as incidental radiographic findings. We report a case of massive and firm calcifications at the left atrium in patient who underwent mitral valve replacement.
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http://dx.doi.org/10.4250/jcu.2010.18.4.151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021895PMC
December 2010

Identification of trimethylation at C-terminal lysine of pilin in the cyanobacterium Synechocystis PCC 6803.

Biochem Biophys Res Commun 2011 Jan 3;404(2):587-92. Epub 2010 Dec 3.

Mass Spectrometry Research Center, Korea Basic Science Institute, Ochang 363-883, South Korea.

Various post-translational modifications (PTMs) of pilin in Synechocystis sp. PCC 6803 have been proposed. In this study, we investigated previously unidentified PTMs of pilin by mass spectrometry (MS). MALDI-TOF MS and TOF/TOF MS showed that the molecular mass of the C-terminal lysine of pilin was increased by 42Da, which could represent acetylation (ΔM=42.0470) or trimethylation (ΔM=42.0106). To discriminate between these isobaric modifications, the molecular mass of the C-terminal tryptic peptide was measured using 15T Fourier transform ion cyclotron resonance (FT-ICR) MS. The high magnetic field FT-ICR provided sub-ppm mass accuracy, revealing that the C-terminal lysine was modified by trimethylation. We could also detect the existence of mono- and di-methylation of the C-terminal lysine. Cells expressing a pilin point mutant with glutamine replacing the C-terminal lysine showed dramatically reduced motility and short pili. These findings suggest that trimethylation of pilin at the C-terminal lysine may be essential for the biogenesis of functional pili.
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http://dx.doi.org/10.1016/j.bbrc.2010.11.133DOI Listing
January 2011
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