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Chae, Gyung Joon,Lee, Sang Bae,Jung, Ui Won,Lee, Yong Keun,Kim, Chong Kwan,Choi, Seong Ho Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.342 No.-
<P>The purpose of this study was to evaluate the osteogenesis of tetracycline blended chitosan membranes on the calvarial critical size defect in Sprague Dawley. An 8 mm surgical defect was created with a trephine bur in the area of the midsagittal suture. Forty rats were divided into four groups: negative control group, positive control group and two experimental groups. Three types of membranes were made and a comparative study was done. One type of non-woven membrane was made by chitosan for positive control. The other two types of non-woven membranes were made by immersing non-woven chitosan into either the tetracycline solution or the chitosan-tetracycline solution. Histologic analysis was done at 2 weeks and 8 weeks of healing periods. We concluded that that the use of tetracycline blended chitosan membrane on the calvarial defects in rats has a significant effect on the regeneration of bone tissue in itself. In addition it implicates that tetracycline blended chitosan membrane may be useful for guided tissue regeneration.</P>
Chae, Gyung-Joon,Jung, Ui-Won,Jung, Sung-Min,Lee, In-Seop,Cho, Kyoo-Sung,Kim, Chong-Kwan,Choi, Seong-Ho John Wiley Sons, Ltd. 2008 Surface and interface analysis Vol.40 No.3
<P>The development and expanded use of dental implants has been remarkably increased. The implant stability and osseointegration are important factors in the success of treatment. Commercially pure titanium and its alloys are the most commonly used materials for endosseous dental implants. Hydroxyapatite (HA), one of the calcium phosphate, has been studied for biomedical applications since it has similarity in chemistry with inorganic components of human bone and its biocompatibility. But the use of HA coated dental implants remain still controversial, because some reports suggest that the HA coating may separate from the substructure, undergo dissolution in tissue fluids, and contribute to rapid breakdown around the implants. HA coating can be applied on metal implants by numerous methods. Of several coating methods, ion beam-assisted deposition (IBAD) has shown to promise. This study was to compare the healing response of various nano-coating surface implants (by IBAD) placed in surgically created circumferential gaps 12 weeks postplacement.</P><P>In six mongrel dogs, all mandible premolars and the first molar were extracted and after an 8-week healing period, four kinds of implants were placed. 2 mm circumferential coronal defects around the implants were performed surgically with a customized step drill. Groups were divided according to the fixture surfaces. The dogs were sacrificed following a 12 week healing period. Specimens were analyzed histologically and histomorphometrically.</P><P>During the healing period, healing was uneventful and implants were well maintained. The bone-to-implant contact (BIC) for experimental groups —calcium phosphate coating implants with or without heat treatment- were much higher than the control group. The defect fill were also higher in the experimental groups. In the control group, the coronal part showed minimal bone fill and osseointegration.</P><P>Within the scope of this study, calcium phosphate coating using IBAD may improve the bone response and the calcium phosphate coating may therefore be suitable in implant design with complex surface geometries. Copyright © 2008 John Wiley & Sons, Ltd.</P>
Chae, Gyung-Joon,Lim, Hyun-Chang,Choi, Jung-Yoo,Chung, Sung-Min,Lee, In-Seop,Cho, Kyoo-Sung,Kim, Chong-Kwan,Choi, Seong-Ho Korean Academy of Periodontology 2008 Journal of Periodontal & Implant Science Vol.38 No.2
Purpose: The aim of this study is to compare the healing response of various Hydroxyapatite(HA) coated dental implants by Ion-Beam Assisted Deposition(IBAD) placed in the surgically created circumferential gap in dogs. Materials and methods: In four mongrel dogs, all mandibular premolars and the first molar were extracted. After an 8 weeks healing period, six submerged type implants were placed and the circumferential cylindrical 2mm coronal defects around the implants were made surgically with customized step drills. Groups were divided into six groups : anodized surface, anodized surface with 150nm HA and heat treatment, anodized surface with 300nm HA and heat treatment, anodized surface with 150nm HA and no heat treatment, and anodized surface with 150nm HA, heat treatment and bone graft, anodized surface with bone graft. The dogs were sacrificed following 12 weeks healing period. Specimens were analyzed histologically and histomorphometrically. Results: During the healing period, healing was uneventful and implants were well maintained. Anodized surface with HA coating and $430^{\circ}C$ heat treatment showed an improved regenerative characteristics. Most of the gaps were filled with newly regenerated bone. The implant surface was covered with bone layer as base for intensive bone formation and remodeling. In case that graft the alloplastic material to the gaps, most of the coronal gaps were filled with newly formed bone and remaining graft particles. The bone-implant contact and bone density parameters showed similar results with the histological findings. The bone graft group presented the best bone-implant contact value which had statistical significance. Conclusion: Within the scope of this study, nano-scale HA coated dental implants appeared to have significant effect on the development of new bone formation. And additional bone graft is an effective method in overcoming the gaps around the implants.
Kim, Joon-Il,Yun, Jeong-Ho,Chae, Gyung-Joon,Jung, Sung-Won,Kim, Chang-Sung,Cho, Kyoo-Sung Korean Academy of Periodontology 2008 Journal of Periodontal & Implant Science Vol.38 No.2
Purpose: The carrier for the delivery of bone morphogenetic proteins(BMPs) should also serve as a scaffold for new bone growth. In addition, predictable bone formation in terms of the volume and shape should be guaranteed. This study evaluated the ectopic bone formation of recombinant human BMP-2(rhBMP-2) using a micro macroporous biphasic calcium phosphate (MBCP: mixture of ${\beta}TCP$ and HA) block as a carrier in a rat subcutaneous assay model. Materials and Methods: Subcutaneous pockets were created on the back of 40 male Sprague-Dawley rats. In the pockets, rhBMP-2/MBCP and MBCP alone were implanted. The blocks were evaluated by histological and histometric parameters after a healing interval of 2 weeks (each 10 rats; MBCP and rhBMP-2/MBCP) or 8 weeks (each 10 rats; MBCP and rhBMP-2/MBCP). Results: The shape and volume of the block was maintained stable over the healing period. No histological bone forming activity was observed in the MBCP alone sites after 2 weeks and there was minimal new bone formation at 8 weeks. In the rhBMP-2/MBCP sites, new bone formation was evident in the macropores of the block. The new bone area at 8 weeks was greater than at 2 weeks. There was a further increase in the quantity of new bone with the more advanced stage of remodeling. Conclusions: A MBCP block could serve as a carrier system for predictable bone tissue engineering using rhBMPs.
사람의 혈관간세포에서 Cyclosporine이 반응성 신소종(Reactive Oxygen Species)과 세포의 기질 축적에 미치는 영향
김현준,강경원,강종명,이수진,채현기,공구 대한신장학회 2000 Kidney Research and Clinical Practice Vol.19 No.6
Objective: Treatment with cyclosporine(CsA) for a long-term period may induce renal glomerulosclersosis and interstitial fibrosis. Reactive oxygen species(ROS) seems to be involved in the process of glomerulosclersosis and interstitial fibrosis. We investigated the effect of CsA on the generation of ROS and extracellular matrix accumulation in cultured human mesangial cells. We also studied the relationship between ROS formation and extracellular matrix and the effect of antioxidant on ROS formation and/or extracellular matrix degradation. Methods: Mesangial cells were treated with varying dose of Cyclosporine(0, 2.5, 5, 7.5 and 10 μg/mL) and also with cyclosporine(5μg/mL) plus N-acetylcysteine(lmM). ROS was measured by flow cytometric analysis. mRNA expression of MMP-2, TIMP-2, MT1-MMP and collagen III was assessed by RT-PCR method. MMP-2 activity was measured by gelatin zymography. Results: No significant difference was noted in cell viability with each CsA concentration. CsA inhibited the cell proliferatn in a dose dependent manner and induced the expression of ROS. Antioxidant NAC reversed the effect of cyclosporine. CsA had no effect on the mRNA expression of collagen III, MMP-2, TIMP-2, MT1-MMP. However CsA decreased the MMP-2 activity in a dose dependent manner, which was also reversed by NAC. Conclusion: Cyclosporine-induced ROS may be associated with the extracellular matrix accumulation, that is glomerulosclersosis and interstitial fibrosis by inhibiting the cell proliferation and by decreasing the degradation of extracellular matrix. Antioxidant, at least in vitro, may prevent some of the adverse effects of CsA on renal function.