• The Korean Journal of Mycology
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• v.41 no.4
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• pp.218-224
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• 2013

Of 1,100 yeast strains which were isolated from various Korean fermented foods, screened for phosphate solubilization, five strains showed the ability to solubilize tricalcium phosphate. The 26S rDNA domain D1-D2 sequence analysis revealed the identification of strain Y393 and Y524 as Pichia anomala (99.8 and 100% identity, respectively), Y669 as Pichia farinosa (100% identity), Y901 as Candida versatilis (100% identity), and Y1101 as Pichia subpelliculosa (100% identity). All the phosphate solubilizing strains showed mesophilic characteristics. The temperature range for growth of 4 strains was $20{\sim}35^{\circ}C$ and P. farinosa Y669 was able to grow up to $45^{\circ}C$. The strain C. versatilis Y907 was able to grow at pH range of 5.0~6.0 and showed halophilic characteristics with tolerance to 15% of NaCl concentration. The Phosphate solubilizing yeast strains were survived well in bed soil for 8 weeks which were maintained densities of $10^7{\sim}10^8$ cfu/g. The highest phosphate solubilizing activity was observed in P. subpelliculosa Y1101. It solubilized 697.2 ug/mL of phosphorus from tricalcium phosphate with decrease in pH from 6.8 to 4.37 after 11 days of inoculation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1273-1281
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• 2014

Tissue engineering is an emerging research field that has the potential to restore, regenerate and repair damaged bone tissue and organs. Tricalcium phosphate and hydroxyapatite biomaterials-based calcium phosphate are excellent materials that have both osteoconduction and biocompatibility for bone tissue regeneration. In this study, solution structures were successfully fabricated using a fused deposition modeling system based on deposition and heating devices. The morphology characteristics of the bioceramic scaffolds sintered at a temperature of $1,300^{\circ}C$ were analyzed by scanning electron microscopy. The effects of various blended TCP/HA ratio on the microstructure and shrinkage were studied. The mechanical properties of the scaffolds were measured using a compression testing machine from stress-strain curves on the crosshead velocity of 1 mm/min. The fabricated scaffolds were evaluated by cell proliferation tests of MG-63 cells. The results of this study suggest that the blended TCP(75 wt%)/HA(25 wt%) scaffold is an appropriate scaffold for bone tissue regeneration.

• The korean journal of orthodontics
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• v.44 no.3
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• pp.113-118
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• 2014

Objective: The purpose of this in vitro study was to examine the effects of fluoridated, casein phosphopeptide-amorphous calcium phosphate complex (CPP-ACP)-containing, and functionalized ${\beta}$-tricalcium phosphate (fTCP)-containing toothpastes on remineralization of white spot lesions (WSLs) by using Quantitative light-induced fluorescence (QLF-D) Biluminator$^{TM}$ 2. Methods: Forty-eight premolars, extracted for orthodontic reasons from 12 patients, with artificially induced WSLs were randomly and equally assigned to four treatment groups: fluoride (1,000 ppm), CPP-ACP, fTCP (with sodium fluoride), and control (deionized water) groups. Specimens were treated twice daily for 2 weeks and stored in saliva solution (1:1 mixture of artificial and human stimulated saliva) otherwise. QLF-D Biluminator$^{TM}$ 2 was used to measure changes in fluorescence, indicating alterations in the mineral contents of the WSLs, immediately before and after the 2 weeks of treatment. Results: Fluorescence greatly increased in the fTCP and CPP-ACP groups compared with the fluoride and control groups, which did not show significant differences. Conclusions: fTCP- and CPP-ACP-containing toothpastes seem to be more effective in reducing WSLs than 1,000-ppm fluoride-containing toothpastes.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.1
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• pp.38-50
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• 2013

Purpose: The aim of this study is to evaluate the effect and potential of electron beam (E-beam) irradiation treatment to the synthetic bony mixtures composed of hydroxyapatite (HA; Bongros$^{(R)}$, Bio@ Co., Korea) and tricalcium phosphate (${\beta}$-TCP, Sigma-Aldrich Co., USA), mixed at various ratios and of type I collagen (Rat tail, BD Biosciences Co., Sweden) as an organic matrix. Methods: We used 1.0~2.0 MeV linear accelerator and 2.0 MeV superconductive linear accelerator (power 100 KW, pressure 115 kPa, temperature $-30{\sim}120^{\circ}C$, sensor sensitivity 0.1~1.2 mV/kPa, generating power sensitivity 44.75 mV/kPa, supply voltage $5{\pm}0.25$ V) with different irradiation dose, such as 1, 30 and 60 kGy. Structural changes in this synthetic bone material were studied in vitro, by scanning electron microscopy (SEM), elementary analysis and field emission scanning electron microscope (FE-SEM), attenuated total reflection (ATR), and electron spectroscopy for chemical analysis (ESCA). Results: The large particular size of HA was changed after E-beam irradiation, to which small particle of TCP was engaged with organic collagen components in SEM findings. Conclusion: The important new in vitro data to be applicable as the substitutes of artificial bone materials in dental and medical fields will be able to be summarized.

• Journal of the Korean Society of Radiology
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• v.5 no.1
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• pp.11-18
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• 2011

The periosteum contains multipotent cells that can differentiate into osteoblasts and chondrocytes. Cultured periosteum-derived cells (PDCs) have an osteogenic capacity. The purpose of this study was to evaluate the interaction of PDCs with bone graft biomaterial. After cell isolation from the calvarial periosteum of Sprague-Dawley rats, cultured PDCs were placed in critical-sized calvarial defects with beta-tricalcium phosphate (${\beta}$-TCP). All rats were sacrificed 8 weeks after bone graft surgery, and the bone regenerative ability of bone grafting sides was evaluated by plain radiography, micro-computed tomography (CT), and histological examination. PDCs grafted with ${\beta}$-TCP displayed enhanced calcification in the defect site, density of regenerated bone and new bone formation within the defect and its boundaries. Furthermore, these PDCs more efficiently regenerated new bone as compared to grafted ${\beta}$-TCP only. The results suggest that cultured PDCs have the potential to promote osteogenesis in bone defects.

• 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.

• Archives of Craniofacial Surgery
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• v.19 no.3
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• pp.181-189
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• 2018

Background: Autogenous bone grafts have several limitations including donor-site problems and insufficient bone volume. To address these limitations, research on bone regeneration is being conducted actively. In this study, we investigate the effects of a three-dimensionally (3D) printed polycaprolactone (PCL)/tricalcium phosphate (TCP) scaffold on the osteogenic differentiation potential of adipose tissue-derived stem cells (ADSCs) and bone marrow-derived stem cells (BMSCs). Methods: We investigated the extent of osteogenic differentiation on the first and tenth day and fourth week after cell culture. Cytotoxicity of the 3D printed $PCL/{\beta}-TCP$ scaffold was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, prior to osteogenic differentiation analysis. ADSCs and BMSCs were divided into three groups: C, only cultured cells; M, cells cultured in the 3D printed $PCL/{\beta}-TCP$ scaffold; D, cells cultured in the 3D printed $PCL/{\beta}-TCP$ scaffold with a bone differentiation medium. Alkaline phosphatase (ALP) activity assay, von Kossa staining, reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting were performed for comparative analysis. Results: ALP assay and von Kossa staining revealed that group M had higher levels of osteogenic differentiation compared to group C. RT-PCR showed that gene expression was higher in group M than in group C, indicating that, compared to group C, osteogenic differentiation was more extensive in group M. Expression levels of proteins involved in ossification were higher in group M, as per the Western blotting results. Conclusion: Osteogenic differentiation was increased in mesenchymal stromal cells (MSCs) cultured in the 3D printed PCL/TCP scaffold compared to the control group. Osteogenic differentiation activity of MSCs cultured in the 3D printed PCL/TCP scaffold was lower than that of cells cultured on the scaffold in bone differentiation medium. Collectively, these results indicate that the 3D printed PCL/TCP scaffold promoted osteogenic differentiation of MSCs and may be widely used for bone tissue engineering.

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.57-67
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• 2002

The effect of $\beta$-TCP and PHA as additives on initial setting time, compressive strength and surface micro-structure after in vitro test of bone cement in TTCP and DCPA system was investigated. The median particle sizes of TTCP, $\beta$-TCP, DCPA and PHA for bone cement were about 3, 5, 0.9 and 4${\mu}{\textrm}{m}$, respectively. Initial setting time and compressive strength of bone cement with various composition was measured by Vicat test and Universal Testing Machine, and surface morphology and crystalline phases of bone cements were observed and analyzed by SEM and x-ray diffractometer. Initial setting time was not affected by composition but by powder/liquid ratio, and cement with PHA required double amount of solution for paste as much as one without PHA, especially. It was thought that $\beta$-TCP and PHA in bone cements was not related to setting reaction. Thus, the addition of $\beta$-TCP and PHA in bone cements decreased compressive strength and inhabited HAP from being produced on surface in vitro test. In conclusion, it was not expected that $\beta$-TCP and PHA in TTCP-DCPD bone cements enhanced the strength and bioacitivity.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.278-286
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• 1995

Phosphate-solubilizing microorganisms were isolated from agricultural area in Korea, and the solubilizing potential of microorganisms was evaluated in vitro. Of the several microorganisms Pseudomonas putida, Penicillium sp., and Aspergillus niger showed solubilization in all phosphatic compounds such as hydroxyapatite, tricalcium phosphate, aluminium phosphate and rock phosphate tested. Inorganic P solubilization was directly related to the pH drop by each microorganisms. Aspergillus niger was found to be more active in solubilizing phosphate than Pseudomonas putida and Penicillium sp.. The maximum concentration of phosphorus released from each of aluminium phosphate, hydroxyapatite and tri-calcium phosphate by Aspergillus niger in liquid culture was 776ppm, 665ppm and 593ppm, respectively when $KNO_3$ was added as nitrogen source. For rock phosphate, it was 411ppm with ammonium sulfate as nitrogen source.

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2006.05a
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• pp.204-204
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• 2006