• Polymer(Korea)
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• v.24 no.6
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• pp.751-756
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• 2000

The copolymerization of ethylene (E) and cycloolefin (CO) was carried out with rac-Et(Ind)$_2$ZrC $l_2$ and MMAO cocatalyst system to examine the effect of CO structure on catalytic behaviors and properties of copolymer (COC). Various cycloolefins such as norbornene (N), 5-phenyl-2-norbornene (PN) and 5-vinyl-2-norbornene (VN) were used as comonomers. With increasing [CO]/[E] feed ratio, the catalytic activity decreased while the glass transition temperature of copolymer increased. With analysis of the structure of E/VN copolymer by FT-IR and $^{l3}$C-NMR, it was found that the cyclic C=C bond of VN comonomer is selectively polymerized and the vinyl C=C bond remains unreacted. The resulting vinyl C=C bond attached into copolymer provided the functionalization moiety using glycidyl methacrylate.e.

• Archives of Plastic Surgery
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• v.36 no.1
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• pp.46-50
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• 2009

Purpose: Finger injury by green onion cutting machine is one of the common hand injuries in the kitchen. It has a unique feature: there are multiple parellel laceration 3 - 5 mm wide. There are two directions of injuries(vertical, oblique). It may involve bone, tendon, nerve, and vessel injuries. We discuss its management and the long - term progress. Methods: We have treated six patients from 2003 to 2007. We carried out low tension approximation with thin suture materials to avoid ischemia and performed the additional operation as nail bed repair, tenorrhaphy, open reduction, vessel anastomosis, and composite graft. We reviewed the record of initial injury and collected the follow - up record. Results: They were all middle aged - women who had worked in the kitchen. Right hand was dominent over left hand. The ratio of the directions was 3 : 3 (vertical : oblique). They were all competely healed although there were three atrophy, four hyperesthesia, and one nail deformity. Conclusion: Finger injury by green onion cutting machine is a unique pattern of laceration with various accompanied injuries. It may look like a severe form of injury, but in most cases have relatively favorable progress. We have to perform careful examination of accompanied injuries and carry out the proper management. First and foremost, the user especially in the middle aged women should be warned to be careful in handling this risky machine.

• Journal of Chest Surgery
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• v.25 no.12
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• pp.1383-1390
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• 1992

This is the result of the annual statistic analysis of thoracic and cardiovascular surgical cases in 1991, Korea. 14,715 cases of surgery[thoracic 8,995/cardiovascular 5,720] were done by 53 institutes replied. The order of frequency of cell type in primary lung cancer was squamous [62.3%] / adeno [23.9%] / small [6.4%] / adenosquamous [3.0%], and in mediastinal tumor, neurogenic[27.l%] / thymoma [27.1%] / teratoma[26.4%] / congenital cystic[12.0%]. Surgery for tuberculosis was decreased to 15.8% of overall infectious disease from the recent 6 year`s average 35.7%. In general thoracic surgery, the single most frequent operation was closed thoracostomy[4,047 cases] for pleural pathology. The ratio of congenital to acquired heart disease was 2:1, and acyanotic to cyanotic was 3:1. The order of frequency of congenital acyanotic heart disease was VSD [45.6%] / ASD [25.6%] / PDA [20.4%] / PS [2.9%], and that of cyanotic heart disease was TOF [42.6%] / PA [12.9%] / TGA [9.9%] / DORV [8.8%]. In 1,364 cases of valvular surgery, single mitral pathology was the most frequent candidate[729 cases, 53.4%]. In 243 cases of coronary surgery, bypassing graft materials were great saphenous vein[41.6%], internal mammary [39.5%], and artificial vessel[18.9%]. There were no specific differences in aortic surgery, assisted device implantation, and antiarrhythmic surgery as compared to previous study. This nation-wide inquiry will be continued and reported annually by KTCS Society.

• Archives of Plastic Surgery
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• v.36 no.6
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• pp.720-726
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• 2009

Purpose: Fasciocutaneous flap with random pattern flap has limitation in mobility and length - width ratio. This characteristic is more pronounced in lower extremity which has relatively poor vascularity. Perforator based flap in lower extremity reconstruction has various advantages as a axial flap, allowing abundant blood supply and widening of mobility range. So if it is not a case of wide defect, free flap can be replaced by perforator based flap. Methods: From April 2007 to March 2009, 18 cases of perforator flap were performed. 8 had defect in upper 1/3 of calf, 6 in middle 1/3, and 4 in lower 1/3. In 10 cases island flap were used, 3 case had transposition flap, 2 cases used advancement flap, 2 case had propeller flap and 1 case had rotation flap. Results: 17 cases survived without flap necrosis. Partial flap necrosis occurred in 1 case, so secondary split thickness skin graft was done. Chronic wound with pseudomonas infection occurred in 1 case, but it was completely cured with conservative treatment. Conclusion: Perforator based flap is useful in lower extremity reconstruction because of relative freedom in changing the size and thickness of the flap depending on the recipient site, good mobility, and abundant vascularity. And donor site morbidity can be minimized. Lower extremity reconstruction using perforator based flap is a good method because it can minimize the complication and obtain effective result.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.607-611
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• 2007

To improve transfection efficiency, we prepared histidine-low molecular weight water-soluble chitosan (LMWSC) having the potential to form complex with DNA as a cationic polymer. Histidine-LMWSC was synthesized by the esterification reaction and removing phthaloyl group. The histidine-LMWSC was characterized using FT-IR, $^1H$ NMR spectra. Histidine-LMWSC was complexed with plasmid DNA (pDNA) in various polymer/DNA (N/P) weight ratios, and the complex was identified using gel retardation assay. The particle sizes of the hisitidine-LMWSC/DNA complexes were measured on a DLS instrument by fixing the histidine-LMWSC/DNA weight ratio of 10/1. Owing to the utilization of a large excess amount of cationic LMWSC against anionic DNA, the particle size of histidine-LMWSC/DNA complexes was in the range of 100~200 nm. Therefore, histidine-LMWSC will be useful in the development of gene carriers.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.1
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• pp.27-35
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• 2006

Purpose: This study was performed to investigate the expression of the transforming growth factor (TGF)-1, in a rat calvarium defect model using particulate dentin and/or plaster of Paris, and correlate the bone regeneration process with the histologic events. Materials and Methods: Thirty-two Sprague-Dawley rats were divided into 4 groups of 8 animals each. A 1.0 cm-sized calvarial defects were made and the defect was filled with different graft materials as follows : Group A, the defects were filled with a mixture of particulate dentin and plaster of Paris with a 2:1 ratio; Group B, the defects were filled with plaster of Paris only; Group C, defects were filled with particulate dentin only; Group D, untreated control group. The animals were sacrificed by 1, 2, 4, 8 weeks after implantation. Excised wound tissues were processed for histology, immunohistochemistry and RT-PCR for the analysis of TGF-1 expression. Results: Gene expression of TGF-1 was detected for all experimental groups. The highest gene expression was observed in the specimen taken at the first week after implantation in Group A. According to the histologic and immunohistochemical studies, TGF-1 positive osteoblast-like cells were found in the early stage of healing after the implantation of particulate dentin and plaster of Paris. Conclusion: These findings suggest that TGF-1 may be related to new bone formation at the early healing process after the implantation of particulate dentin and plaster of Paris.

• Clinical and Experimental Pediatrics
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• v.62 no.11
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• pp.422-427
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• 2019

Background: Polyomavirus BK (BKV) infection is an important cause of graft loss in kidney transplant patients. Purpose: The purpose of this study was to evaluate clinical findings and risk factors for BKV in pediatric patients after kidney transplantation. Methods: This retrospective single-center study included 31 pediatric kidney transplant recipients from January 2002 to December 2017. Two patients received 2 transplantations during the study period, and each transplant was analyzed independently. Total number of cases is 33 cases with 31 patients. BKV infection was confirmed from blood samples via periodic quantitative polymerase chain reaction. Results: The mean age at kidney transplantation was 11.0±4.7 years, and the male-to-female ratio was 2.7:1. Three patients had a past medical history of high-dose chemotherapy and autologous stem-cell transplantation for solid tumors. Nine patients (27.3%) developed BKV infection. The median period from kidney transplantation to BKV detection in blood was 5.6 months. There was no statistically significant difference in estimated glomerular filtration rate between patients with and those without BKV infection. Among 9 patients with BKV viremia, 7 were treated by reducing their immunosuppressant dose, and BKV was cleared in 6 of these 7 patients. In the other 2 BKV-positive patients, viremia improved without immunosuppressant reduction. Conclusion: BKV infection is common in children with kidney transplantation and might not have affected short-term renal function in our patient sample due to early immunosuppressant reduction at the time of BKV detection.

• Elastomers and Composites
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• v.47 no.2
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• pp.162-167
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• 2012

Surface modification of macromolecules renders a progressive and favorable method to enhance the properties of polymeric materials and improves conductivity, wettability, stability, adhesion, antibacterial properties, etc. of polymeric surfaces without deterioration of the polymer bulk properties. Polyolefins such as polyethylene and polypropylene were grafted with maleic anhydride(MAH) as a functional monomer in solution. Evidence for grafting was shown with FTIR measurement. The grafting ratio was determined from chemical titration. The higher MAH loading, the lower contact angle(${\theta}$) was obtained. With the increasing content of MAH, melting temperature($T_m$) of maleic anhydride grafted polymer decreased while decomposition temperature($T_d$) of maleic anhydride grafted polymer increased.

• Journal of Trauma and Injury
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• v.21 no.2
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• pp.128-135
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• 2008

Purpose: As the care of surgical patients becomes increasingly complex and catheter-based techniques are more frequently applied, the pattern of iatrogenic vascular injuries may be increasing. Major vascular injuries can jeopardize a patient's life or limb survival. The purpose of this study was to examine the current etiology and prognosis for iatrogenic vascular injuries. Methods: We reviewed medical records of 29 cases of iatrogenic vascular injury that were treated Seoul National University Bundang Hospital between October 2003 and October 2008. We studied clinical variables including demographics, cause of injury, clinical presentations, management and prognosis. Results: The mean age was 60.8 years (range: 25-86), and the male to female ratio was 1.9 : 1. The causes of injuries were operation related complication in 18 cases (62.1%), endovascular intervention and diagnostic angiography in 11 cases (37.9%). The types of vascular injury were partial severance in 14 cases, pseudoaneurysm in 8, arteriovenous fistula (AVF) in 3, thrombosis in 2, complete severance in 2. Especially, device related complication including percutaneous closing device were occurred in 9 and the others came from inadvertent physician's procedure. Primary repair were done in 12 cases, end-to-end anastomosis in 5, interposition graft in 4, ligation in 2, patch angioplasty in 1, peudoaneurysm excision and arteriorrhaphy in 1, hematoma evacuation in 1, and endovascular repair in 3. There were 2 cases of mortality, one of them due to hemorrhagic shock and the other due to septic shock. Conclusion: Proper selection of treatment modalities should be important to have better outcome according to the type of injury as well as anatomical location. Each physician should be familiar to new device as well as patient's topographical feature. Immediate referral to vascular specialist is also essential to reduce morbidity.

• Korean Journal of Transplantation
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• v.31 no.4
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• pp.200-206
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• 2017

Background: Risk factors for bone avascular necrosis (AVN), a common late complication after kidney transplantation (KT), are not well known. Methods: Patients that underwent living-donor KT at Asan Medical Center between January 2009 and July 2016 were included in this retrospective study to determine the incidence and risk factors for AVN after KT. Results: Among 1,570 patients that underwent living-donor KT, 33 (2.1%) developed AVN during a mean follow-up of 49.8±25.0 months. Additionally, AVN was diagnosed at a mean of 13.9±6.6 months after KT. The mean cumulative corticosteroid dose during the last follow-up in patients without AVN (9,108±3,400 mg) was higher than that that in patients with AVN (4,483±1,114 mg) until AVN development (P<0.01). More patients among those with AVN (n=4, 12.1%) underwent steroid pulse treatment because of biopsy-proven rejections during the first 6 months after KT than patients without AVN (n=68, 4.4%; P=0.04). Female (hazard ratio [HR], 2.29; P=0.04) and steroid pulse treatment during the first 6 months (HR, 2.31; P=0.02) were significant AVN risk factors as revealed by the Cox proportional multivariate analysis. However, no significant differences in rejection-free graft survival rates were observed between the two groups (P=0.67). Conclusions: Steroid pulse treatment within 6 months of KT and being female were independent risk factors for AVN development.