• Journal of Pharmaceutical Investigation
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• v.41 no.2
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• pp.95-102
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• 2011

An amphiphilic cationic branched methoxy poly (ethylene glycol)-branched polyethylenimine - poly(L-phenylalanine) (mPEG-bPEI-pPhe) block copolymer was successfully synthesized by ring-opening polymerization (ROP) of N-carboxyanhydride of L-phenylalanine (Phe-NCA) with mPEG-bPEI for the preparation of more stable polyelectrolyte complex (PEC) included a hydrophobic interaction. mPEG-bPEI was firstly prepared by the coupling of mPEG and bPEI using hexamethylene diisocyanate (HMDI). The structural properties of mPEG-bPEI-pPhe copolymers were confirmed by $^1H$ NMR. The copolymers exhibited a self-assemble behavior in water above critical aggregate concentration (CAC) in the range of 0.01-0.14 g/L. The CAC of copolymers obviously depended on the hydrophobic block content in the copolymers (the value decreased with the increase of the pPhe block content). The cationic copolymers have the ability to form multi-interaction complex (MIC) with bovine serum albumin (BSA) and plasmid DNA through multi-interaction (electrostatic and hydrophobic interaction). The physicochemical characterization of the complex was carried out by the measurement of zeta potential and particle size. Their zeta-potentials were positive (approximately +10 mV) and their sizes decreased with increasing pPhe contents in the copolymers (PPF/BSA wt% ratio = 2). The complex showed good stability at high ionic strength. Therefore, mPEG-bPEI-pPhe block copolymer was considered as a potential material to enhance the stability of complex including biotherapuetic drugs.

• Parasites, Hosts and Diseases
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• v.43 no.1 s.133
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• pp.27-32
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• 2005

Toxoplasma gondii tachyzoites were isolated from an ocular patient in the Republic of Korea and maintained in the laboratory (designated KI-1). In the present study, its genotype was determined by analyzing dense granule antigen 6 (GRA6) gene and surface antigen 2 (SAG2) gene as typing markers. Digestion of the amplification products of GRA6 and of the 5' and 3' ends of SAG2, respectively, with Mse I, Sau3A I, and Hha I, revealed that KI-1 is included in the genotype I, which includes the worldwide virulent RH strain. In addition, when the whole sequences of the coding regions of SAG1, rhoptry antigen 1 (ROP1), and GRA8 genes of KI-1 were compared with those of RH, minor nucleotide polymorphisms and amino acid substitutions were identified. These results show that KI-1 is a new geographical strain of T. gondii that can be included in the genotype I.

• Clinical and Experimental Pediatrics
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• v.52 no.8
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• pp.881-887
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• 2009

Purpose : The survival rate of very low birth weight infant (VLBWI) had increased as a result of advances in neonatal intensive care. We evaluated the changes in outcomes of VLBWI who admitted to the neonatal care unit of Hallym University Kangnam Sacred Heart Hospital. Methods : Retrospective review of 339 VLBWI who were born from 1st January 1997 to 31th December 2008 were performed. Outcomes including survival rate, birth weight (BW), gestational age (GA), morbidities, and mortality between period I (1997- 2003) and period II (2004-2008) were compared. Results : Overall incidence of VLBWI was 2.3% and it was significantly higher in period II(3.3%). Mean BW and GA were significantly decreased in period II (P<0.001, P=0.01). The survival rate increased from period I (59.1%) to period II (74.2%). BW-specific survival rate increased in 1,000-1,249 gm and GA-specific survival rate significantly increased in 27-28 weeks and 29-30 weeks. The incidences of respiratory distress syndrome (RDS), retinopathy of prematurity (ROP), sepsis, bronchopulmonary dysplasia (BPD), intraventricular hemorrhage, periventricular leukomalacia, and necorotizing enterocolitis were same except patent ductus arteriosus. Conclusion : The survival rate of VLBWI was increased in period II, especially in less than 1,000 gm and below 27 weeks. This may be due to recent dramatic improvement of neonatal care. But more efforts are needed to improve outcome during initial phase and to reduce long term complication such as BPD and ROP.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1800-1808
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• 2013

Dual-responsive amphiphilic block copolymers were synthesized by combining enzymatic ring-opening polymerization (eROP) of ${\varepsilon}$-caprolactone (CL) and ATRP of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). The obtained block copolymers were characterized by gel permeation chromatography (GPC), $^1H$ NMR and FTIR-IR. The critical micelle concentration (CMC) of copolymer was determined by fluorescence spectra, it can be found that with hydrophilic block (PDMAEMA) increasing, CMC value of the polymer sample increased accordingly, and the CMC value was 0.012 mg/mL, 0.025 mg/mL and 0.037 mg/mL for $PCL_{50}$-b-$PDMAEMA_{68}$, $PCL_{50}$-b-$PDMAEMA_{89}$, $PCL_{50}$-b-$PDMAEMA_{112}$, $PCL_{50}$-b-$PDMAEMA_{89}$ was chosen as drug carrier to study in vitro release profile of anti-cancer drug (taxol). The temperature and pH dependence of the values of hydrodynamic diameter (Dh) of micelles, and self-assembly of the resulting block copolymers in water were evaluated by dynamic light scattering (DLS). The result showed that with the temperature increasing and pH decreasing, the Dh decreased. Drug-loaded nanoparticles were fabricated using paclitaxel as model. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) had been explored to study the morphology of the hollow micelles and the nanoparticles, revealing well-dispersed spheres with the average diameters both around 80 nm. In vitro release kinetics of paclitaxel from the nanoparticles was also investigated in different conditions (pH and temperature, etc.), revealing that the drug release was triggered by temperature changes upon the lower critical solution temperature (LCST) at pH 7.4, and at $37^{\circ}C$ by an increase of pH.

• Neonatal Medicine
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• v.25 no.1
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• pp.29-36
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• 2018

Purpose: The purpose of this study was to investigate the outcome after changes in the treatment strategies for very low birth weight infant (VLBWI) in a single neonatal intensive care unit (NICU) center. Methods: We performed a retrospective review of 300 VLBWI born from 1st January 2010 to 31th December 2016. We compared the outcomes including survival rate, birth weight (BW), gestational age (GA), and morbidities between period I (2010-2013, P-I) and period II (2014-2016, P-II). Results: The average survival rate was not different between P-I and P-II. However, the survival rate of ${\leq}24$ weeks' GA, 25 weeks' GA, 26 weeks' GA were 57%, 69%, 93% respectively in P-II and 31%, 59%, 87% in P-I respectively. The survival rate of infants with birth weight <500 g, 500-749 g, 750-999 g were 100%, 55%, 90% respectively in P- II and 50%, 24%, 80%, respectively in P-I. The incidence of bronchopulmonary dysplasia (BPD) was higher in P-II than in P-I (P=0.012) and moderate-to-severe BPD was also higher in P-II (P=0.004). Incidence of patent ductus arteriosus (PDA) with treatment, necrotizing enterocolitis (stage ${\geq}2$), and abnormal brain sonography were significantly lower in P-II (P=0.027, P=0.032, P=0.005). Incidences of retinopathy of prematurity (ROP) with laser treatment and early sepsis were not different. Conclusion: The survival rate and complications of VLBWI were improved in period II, especially in less than 750 g and below 26 weeks, except incidence of BPD. Changes of NICU strategies were effective to improve mortality and morbidity in VLBWI.

• Neonatal Medicine
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• v.18 no.2
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• pp.228-233
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• 2011

Purpose: The aim of our study was to compare the efficacy and safety of ibuprofen and indomethacin in the prophylaxis of patent ductus arteriosus (PDA) in preterm infants and to determine whether ibuprofen could be an alternative agent in prophylactic use. Methods: A retrospective study including 37 preterm infants <1,500 g of birth weight, <34 weeks of gestation, whom were administrated indomethacin (n=17; January 2009-December 2009) or ibuprofen (n=20; January 2010-February 2011) within 24 hr after birth was conducted. The rate of ductal closure, need for surgical ligation, clinical outcomes such as necrotizing enterocolitis, intraventricular hemorrhage, bronchopulmonary dysplasia, retinopathy of prematurity (ROP) and death rate were compared. Results: There were no statistically significant differences between the two groups in mean gestational age, mean birth weight, Apgar score, sex, type of delivery, maternal dexamethasone treatment, frequency and duration of ventilator and surfactant treatment. The closure of PDA on day 7 of life was in 19 of 20 infants of the ibuprofen group and 13 of 17 infants of the indomethacin group (P=0.159). Between the two groups, there were no significant differences with respect to clinical outcomes. Conclusion: Ibuprofen has similar effects to indomethacin in the rate of PDA closure. Our study demonstrates that prophylactic ibuprofen is relatively effective without significant differences with respect to clinical outcomes compared with indomethacin. Therefore, ibuprofen may be used as an alternative agent in the prophylaxis of PDA in preterm infants.

• Polymer(Korea)
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• v.35 no.1
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• pp.52-59
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• 2011

L-PLA or D-PLA was synthesized in bulk at $140^{\circ}C$ by ring opening polymerization(ROP) of L-lactide or D-lactide as a monomer using tin(II) octoate and lauryl alcohol as a catalyst and an initiator with changing the amounts of catalyst(0.25~1.0 wt%) and initiator(0.l~0.5 wt%). And stereocomplex-PLA was prepared by L-PLA/D-PLA having a wide range of molecular weight(30000~90000 g/mol) and L-PLA/D-PLA blends having different mixing ratio ($X_D$). The melting temperature. thermal degradation temperature and thermal stability of stereocomplex-PLA were higher than those of homopolymers(L-PLA, D-PLA). We supposed that these improvements arose from a strong interaction between L-PLA and D-PLA. The improved mechanical properties and changes in morphology of LPLA/D-PLA blends were compared to those of homopolymers(L-PLA, D-PLA).

• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.135-147
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• 2017

We, for the first time, estimated daily and monthly surface nitrogen dioxide ($NO_2$) volume mixing ratio (VMR) using three regression models with $NO_2$ tropospheric vertical column density (OMIT-rop $NO_2$ VCD) data obtained from Ozone Monitoring Instrument (OMI) in Seoul in South Korea at OMI overpass time (13:45 local time). First linear regression model (M1) is a linear regression equation between OMI-Trop $NO_2$ VCD and in situ $NO_2$ VMR, whereas second linear regression model (M2) incorporates boundary layer height (BLH), temperature, and pressure obtained from Atmospheric Infrared Sounder (AIRS) and OMI-Trop $NO_2$ VCD. Last models (M3M & M3D) are a multiple linear regression equations which include OMI-Trop $NO_2$ VCD, BLH and various meteorological data. In this study, we determined three types of regression models for the training period between 2009 and 2011, and the performance of those regression models was evaluated via comparison with the surface $NO_2$ VMR data obtained from in situ measurements (in situ $NO_2$ VMR) in 2012. The monthly mean surface $NO_2$ VMRs estimated by M3M showed good agreements with those of in situ measurements(avg. R = 0.77). In terms of the daily (13:45LT) $NO_2$ estimation, the highest correlations were found between the daily surface $NO_2$ VMRs estimated by M3D and in-situ $NO_2$ VMRs (avg. R = 0.55). The estimated surface $NO_2$ VMRs by three modelstend to be underestimated. We also discussed the performance of these empirical modelsfor surface $NO_2$ VMR estimation with respect to otherstatistical data such asroot mean square error (RMSE), mean bias, mean absolute error (MAE), and percent difference. This present study shows a possibility of estimating surface $NO_2$ VMR using the satellite measurement.

• Korean Journal of Food Science and Technology
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• v.52 no.1
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• pp.1-10
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• 2020

The present study identified the restrictions on the use of sous-vide products in the Korean HMR market for small and medium-sized manufacturing companies. A detailed literature review revealed that the HMR market in Korea is close to saturation. Notably, the technologically advanced products produced using sous-vide seem to display significant potential to overcome market saturation. The sous-vide method differs from conventional cooking techniques and is characterized by maintenance of food texture along with flavor enhancement. However, due to the unfamiliarity of the manufacturers with this method and the unclear food safety regulations, mass food manufacturing companies do not agree on using this method; hence, sous-vide production is usually undertaken by small/medium sized companies catering primarily through online marketing portals. This study highlights the various restrictions to the implementation of sous-vide production, and discusses several practical implications of sous-vide production that would help users of this technique enter the HMR market.

• Neonatal Medicine
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• v.15 no.1
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• pp.44-53
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• 2008

Purpose : Epidemic keratoconjunctivitis (EKC) caused by adenovirus is a highly contagious disease, which has been reported as outbreaks involving adults in the community. However, there has been no report on EKC outbreak by adenovirus in a neonatal intensive care unit (NICU) in Korea. Aims of this study were to investigate the EKC outbreak by adenovirus type 8 in NICU and to confirm an effectiveness of polymerase chain reaction (PCR) for diagnosis. Methods : Conjunctival swab or nasopharyngeal aspirate specimens were taken from all patients and tested by viral culture and PCR. Adenovirus serotype was determined by sequencing of PCR product of selected region of hexon gene using the virus isolates or specimens. Results : An outbreak of EKC occurred which was involving 12 preterm infants in the NICU of the Seoul National University Children's Hospital between July 12th and August 1st, 2005. Three hospital staffs and one family member of the neonate were also affected. Adenovirus was detected in 12/12 (100%), 6/11 (54.5%) by PCR and virus culture, respectively. Eleven PCR-positive neonates were identified as serotype 8 by sequencing. The first affected 4 babies have had routine ROP (retinopathy of prematurity) examinations one week ago. While previous outbreaks were sustained for a few months, the event in our unit was controlled without complications in 3 weeks. Conclusion : We analyzed the EKC outbreak by adenovirus type 8 in NICU. Adenovirus serotype was identified by PCR and sequencing with high sensitivity for the first time in Korea, so we suggest this method can be very useful for rapid diagnosis and infection control.