• Journal of Chest Surgery
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• v.35 no.5
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• pp.369-374
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• 2002

Background: Proper construction of vascular access and adequate maintenance are essential for the prognosis of the hemodialysis patients. Though arteriovenous fistula using autogenous vessel is the first of choice, the incidence of arteriovenous fistula using artificial graft is gradually increasing. The aim of this study was to analyse the patency rates between autogenous and artificial fistula, among artificial graft types, according to the accompanied disease. Material and Method: A retrospective study was conducted on 186 patients who underwent 292 arteriovenous fistula operations for hemodialysis at Korea University Guro Hospital between 1996 and 2000. Mean age of the patients was 54.37 $\pm$ 12.79years, and the male: female ratio 99:87. Result: Among 292 operations, there were 156 autogenous fistula and 116 graft fistula. The other 20 operations were thrombectomy, takedown of graft, revision, and balloon dilatation. Patency rates of autogenous fistula were 92.78 $\pm$ 2.35% at 1 year and 39.03$\pm$9.08% at 5 years, and those of graft fistula were 96.09 $\pm$ 2.22% at 1 year and 16.45 $\pm$ 10.15% at 5 scars. However, there was no statistical significance between the two operations. The patients who had hypertension, diabetes or both had no statistical significance in the patency rate compared to that of patients without underlying disease. In addition, the type of graft used did not affect the patency rate. Second operation was needed in 62 patients and third operation in 31 patients, but their patency rate again had no statistical significance compared to that of the first operation. Conclusion: The patency of the artificial graft fistula was comparable to the autogenous fistula, but the patency according to types of graft need to be studied further. Furthermore, the underlying diseases did not affect the fistula patency.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.318-323
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• 2014

In order to analyze the effect of maleic anhydride (MAH) content and styrene monomer (SM)/MAH mole ratio on reactive extrusion of maleic anhydride grafted random polypropylenes (MAH-g-rPP), MAH-g-rPPs were prepared by using a twin screw extruder. MAH contents were 0.5, 1.0, 3.0, and 5.0 phr and SM/initiator mole ratio was 0.0, 1.0, and 2.0. Dicumyl peroxide (DCP) was used as an initiator. The graft degree of MAH was confirmed by the existence of carbonyl group (C = O) stretching peak at $1700cm^{-1}$ from FT-IR spectrum. The degree of graft reaction increased up to 3.0 phr MAH and showed the optimum value at 1.0 SM/MAH mole ratio from the area ratio of C = O and C-H stretching peak. Thermal and crystallization properties of MAH-g-rPP and PP/MAH-g-rPP/pulp composites were investigated by DSC, TGA, XRD, and POM. There was a decrease in non-isothermal crystallization temperature of PP/MAH-g-PP/pulp composites. Based on tensile properties and SEM pictures for the fractured surface of PP/MAH-g-PP/pulp composites, MAH content of 1.0 wt% and SM/MAH mole ratio of 1.0 were the optimum formulation as the compatibilizer. The rheological properties of the composites were measured by dynamic Rheometer to compare the processability of the composites with and without compatibilizer. The power law index showed slightly low value at the composites with compatibilizer.

• Journal of Chest Surgery
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• v.20 no.4
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• pp.780-785
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• 1987

Pulmonary atresia with VSD is uncommon congenital anomaly with high mortality in neonatal period. Recently we experienced surgical correction of 2 cases of pulmonary atresia with VSD. The first case was 7-year old female patient and diagnosed as pulmonary atresia with VSD combined PDA. So, total correction was undertaken which consisted of PDA ligation, patch repair of VSD, transannular enlargement of RVOT with woven Dacron vascular graft, and closure of PFO. Postoperative systemic Rt. ventricular and radial artery pressure ratio was 0.44 and her postoperative course was uneventful. The second case was 6-year old male patient diagnosed as pulmonary atresia with VSD and large systemic-pulmonary collateral arteries. There were two large systemic-pulmonary collaterals, one was simply controlled by ligation, but the other was considered to supply Rt. upper lung. So end to side anastomosis was performed to the RVOT patch. Postoperative systolic Rt. ventricular and radial artery pressure ratio was 0.54. During the follow up period he showed clinical picture of Rt. heart failure, which is relatively well controlled with anticongestive therapy.

• Korean Membrane Journal
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• v.6 no.1
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• pp.37-43
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• 2004

Comb-type graft hydrogels composed of alginate and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to manifest rapid temperature and pH sensitivity. To appear the electro-sensitivity, the polyaniline, conducting polymer, was added into the matrix. The swelling kinetics and ratios were compared under the various compositions of polyaniline. The swelling behaviors revealed that conducting polymer/hydrogel composites could control the swelling ratio and kinetics. The addition of polyaniline in the matrix improved the thermal stability in comparison with that of the hydrogel without polyaniline. In temperature sensitivity, the adding the polyaniline into the matrix decreased the degree of change in the swelling ratio. The swelling ratios continuously increased with increasing pH values. The drug release rate from the hydrogel increased with the adding the polyaniline and the applying the direct voltage to the hydrogels.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.36-42
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• 1997

Though myocardial perfusion was usually expected to improve after coronary artery bypass graft(CABG) surgery, some myocardial segments were aggravated after operation, as we compared perfusion changes on postoperative SPECT with preoperative ones. In this study, we evaluated perfusion changes after operation in rest and stress myocardial SPECT in 44 patients (M:F=25:19, age 57.1 $year{\pm}8.2$) who had CABG before and 3 months after operation. We tried to find out possible causes for perfusion aggravation with multivariate logistic regression analysis regarding whether bypass graft was artery or vein and which coronary artery territory was operated. Among 616 myocardial segments which were operated, 89(14.4%) aggravated after operation. In the univariate analysis, myocardial segments in the left circumflex arteries(LCx) aggravated more often(p<0.01) than others and segments having operative angioplasty did less often(p<0.01). Multivariate logistic regression revealed that LCx was risk factor for perfusion aggravation [odds ratio=2.54 (95% confidence interval : 1.53-4.22, p<0.01)]. However, this was not the case when we analysed in terms of arterial territories. Among 106 coronary arterial territories which were operated, 27(25.5%) aggravated. The territories having aggravated had similar characteristics regarding whether they received arterial or venous grafts, angioplasty and whether the operated territories were left anterior descending, right coronary or left circumflex arteries. In conclusion, myocardial segments in the left circumflex artery tended to aggravate more often after bypass surgery than the others. In short-term comparison of perfusion after surgery, we could not find any tendency that arterial or venous graft was associated with more frequency of the aggravation of perfusion after operation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.1
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• pp.36-48
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• 2008

To repair bone defects in the oral and maxillofacial field, bone grafts including autografts, allografts, and artificial bone are used in clinical dentistry despite several disadvantages. The purpose of this study was to evaluate new bone formation and healing in rat calvarial bone defects using hydroxyapatite (HA, $Ca_{10}[PO_4]_6[OH]_2,\;Bongros^{(R)}$, Bio@ Co., KOREA) and tricalcium phosphate (${\beta}-TCP,\;Ca_3[PO_4]_2$, Sigma-Aldrich Co., USA) mixed at various ratios. Additionally, this study evaluated the effects of type I collagen (Rat tail, BD Biosciences Co., Sweden) as a basement membrane organic matrix. A total of twenty, 8-week-old, male Sprague-Dawley rats, weighing 250-300g, were divided equally into a control group (n=2) and nine experimental groups (n=2, each). Bilateral, standardized transosseous circular calvarial defects, 5.0 mm in diameter, were created. In each experimental group, the defect was filled with HA and TCP at a ratio of 100:0, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, and 0:100 with or without type I collagen. Rats were sacrificed 4 and 8 weeks post-operation for radiographic (standardized plain film, Kodak Co., USA), histomorphologic (H&E [Hematoxylin and Eosin], MT [Masson Trichrome]), immunohistochemical staining (for BMP-2, -4, VEGF, and vWF), and elementary analysis (Atomic absorption spectrophotometer, Perkin Elmer AAnalyst $100^{(R)}$). As the HA proportion increased, denser radiopacity was seen in most groups at 4 and 8 weeks. In general radiopacity in type I collagen groups was greater than the non-collagen groups, especially in the 100% HA group at 8 weeks. No new bone formation was seen in calvarial defects in any group at 4 weeks. Bridging bone formation from the defect margin was marked at 8 weeks in most type I collagen groups. Although immunohistochemical findings with BMP-2, -4, and VEGF were not significantly different, marked vWF immunoreactivity was present. vWF staining was especially strong in endothelial cells in newly formed bone margins in the 100:0, 80:20, and 70:30 ratio type I collagen groups at 8 weeks. The calcium compositions from the elementary analysis were not statistically significant. Many types of artificial bone have been used as bone graft materials, but most of them can only be applied as an inorganic material. This study confirmed improved bony regeneration by adding organic type I collagen to inorganic HA and TCP mixtures. Therefore, these new artificial bone graft materials, which are under strict storage and distribution systems, will be suggested to be available to clinical dentistry demands.

• Polymer(Korea)
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• v.29 no.2
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• pp.135-139
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• 2005

In this study, poly(ethylene imine) (PEI) modified by methoxypoly(ethylene glycol) (mPEG) and folate as a gene carrier was synthesized to decrease cytotoxicity and to improve in vivo targeting. mPEG was modified by glutaric anhydride (GA) to endow carboxylic end group, followed by the activation reaction with EDC (N-ethyl-N'-(3-dimethyl-aminopropyl) carbodiimide) and NHS (N-hydroxysuccinimide). The activated carboxylic end group of mPEG was reacted with the amines of PEI to give mPEG graft PEI. The mPEG-folate-graft-PEI was synthesized by the reaction of mPEG-PEI with folate pre-activated by EDC/NHS. The obtained copolymers were characterized by $^1H-NMR$ and FT-IR. Gel retardation assay and fluorescence measurement indicated that DNA formed the complexes with the synthesized copolymers above N/P charge ratio 2. The size of complexes was ranging from 100 nm to 300 m. In conclusion, we confirmed that the synthesized copolymer have the possibility as a DNA carrier.

• Journal of Periodontal and Implant Science
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• v.36 no.4
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• pp.797-808
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• 2006

Objective : The purpose of this study was to evaluate the physicochemical properties and cytocompatibility of microporous, spherical biphasic calcium phosphate(BCP) ceramics with a 60/40 $hydroxyapatite/{\beta}$ -tricalcium phosphate weight ratio for application as a bone graft substitute. Materials and Methods : Microporous, spherical BCP granules(MGSB) were prepared and their basic characteristics were compared with commercially available BCP(MBCP; Biomatlante, France) and deproteinized bovine bone mineral(Bio-Oss; GBistlich-Pharma, Switzerland, BBP; Oscotec. Korea), Their physicochemical properties were evaluated by scanning electron microscopy, X-ray diffractometry, Fourier-transform infrared spectroscopy, inductively coupled plasma atomic emission spectrometer, and Brunauer-Emmett-Teller method. Cell viability and proliferation of MC3T3-El cells on different graft materials were evaluated. Results : MGSB granules showed a chemical composition and crystallinity similar with those in MBCP, they showed surface structure characteristic of three dimensionally, well-interconnected micropores. The results of MTT assay showed increases in cell viablity with increasing incubation times. At 4d of incubation, MGSB, MBCP and BBP showed similar values in optical density, but Bio-Oss exhibited significantly lower optical density compared to other bone substitutes(p <0,05). MGSB showed significantly greater cell number compared to other bone substitutes at 3, 5, and 7d of incubation(p <0,05), which were similar with those in polystyrene culture plates. Conclusion: These results indicated the suitable physicochemical properties of MGSB granules for application as an effective bone graft substitute. which provided compatible environment for osteoblast cell growth. However, further detailed studies are needed to confirm its biological effects on bone formation in vivo.

• Korean Journal of Transplantation
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• v.31 no.4
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• pp.182-192
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• 2017

Background: In recent years, introduction of novel immunosuppressive agents and its proper implementation for clinical practice have contributed to improving clinical outcomes of kidney transplantation (KT). Here, we report clinical outcomes of KTs and related risk factors. Methods: From July 1998 to June 2016, 354 KTs (182 from living and 172 from deceased donors) have been performed at Ulsan University Hospital. We retrospectively reviewed the clinical characteristics and outcomes of KT recipients, then estimated graft and patient survival rate were estimated and analyzed risk factors using Cox-regression. Results: The median follow-up period was 53 months (range; 3 to 220 months). The mean ages of recipients and donors were 45.0 years (SD, 12.5) and 44.7 years (SD, 13.6) years, respectively. During follow-up, 18 grafts were lost and 5- and 10-year death-censored graft survival was 96.7% and 91.5%, respectively. Biopsy-proven acute rejection (BPAR) occurred in 71 patients (55 cases of acute cellular rejection and 16 of antibody-mediated rejection). Cox-regression analysis showed that BPAR was a risk factor related to graft loss (hazard ratio [HR], 14.38; 95% confidence interval [CI], 3.79 to 54.53; P<0.001). In addition, 15 patients died, and the 5- and 10-year patient survival was 97.2% and 91.9%, respectively. Age ≥60 years (HR, 6.03; 95% CI, 1.12 to 32.61; P=0.037) and diabetes (HR, 6.18; 95% CI, 1.35 to 28.22; P=0.019) were significantly related to patient survival. Conclusions: We experienced excellent clinical outcomes of KT in terms of graft failure and patient survival despite the relatively high proportion of deceased donors. Long-term and short-term clinical outcomes have improved in the last two decades.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.395-405
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• 1994

The various functional groups, such as hydroxyl(-OH), carboxyl(-COOH) and quinonic oxygen(OC<) on the carbon black(abbreviated to CB) surface were activated with n-butyl lithium solution in n-hexane and then acrylate and methacrylate monomers were graft polymerized onto these activated anionic sites and CB-grafted polymers were obtained. To separate homopolymers from reaction mixture, non-solvent precipitation method or centrifugal separating method were applied. Subsequently, conversion, grafting ratio and efficiency were determined at various reaction temperatures and times. In case of acrylates, the grafting ratio showed 20~30% but methacrylates showed 150~200%. Also the anion polymerizations between CB and monomers were nearly reached to equilibrium state within one or two hours under each reaction temperatures but conversion and grafting ratio were increased a little with reaction temperature increase. In colloidal dispersion stability test, before heat-drying, the all CB-grafted polymers showed good dispersed stability in good solvents for acrylic and methacrylic homopolymers. Futhermore, CB-polymethacrylates were found to show excellent collidal properties for good solvents of methacrylic homopolymer even after heat-drying. Identification of the grafted polyacrylates and polymethacrylates onto the CB surface was performed by FT-IR spectroscopy. In addition, electric resistance values of CB-grafted polymers were measured by Four-probe method, and the increase of the grafting ratio showed the increase of the surface resistance.