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식각된 비귀금속합금과 법랑질을 복합레진계 시멘트로 접착시킨 경우의 접착인장강도에 관한 연구
박헌석,이선형,양재호,장완식,Park, Heon-Seok,Lee, Sun-Hyung,Yang, Jae-Ho,Chang, Wan-Shik 대한치과보철학회 1986 대한치과보철학회지 Vol.24 No.1
The purpose of this study was to compare the tensile bond strength of Comspan and Panavia as a luting materials between electrochemically etched Ni-Cr-Be alloy castings and acid etchea human tooth enamel. Tensile bond strength was evaluated using an Instron testing machine at a crosshead speed of 2mm/min. The following conclusions can be drawn frfm this study ; 1. The tensile bond strength of etched-metal resin-bonded specimen was $179.0{\pm}42.5kg/cm^2$ in case of Comspan and $169.6{\pm}41.4kg/cm^2$ in case of Panavia. 2. The tensile bond strength was not significantly different between Comspan, using with bonding agent, and Panavia, using without bonding agent.
이종 췌도 이식을 위한 Ba²+-알진산 미세피막화 췌도 형성
박헌석 ( Heon Seok Park ),함동식 ( Dong Sik Ham ),유영혜 ( Young Hye You ),신주영 ( Ju Young Shin ),김지원 ( Ji Won Kim ),조재형 ( Jae Hyoung Jo ),김온유 ( On You Kim ),강길선 ( Gil Son Khang ),윤건호 ( Kun Ho Yoon ) 한국조직공학과 재생의학회 2010 조직공학과 재생의학 Vol.7 No.5
Islet transplantation is one of the promising treatment strategies for the cure of diabetes. However, the hurdles such as shortage of human tissue, immune rejection and recurrence of autoimmunity should be overcome for successful islet transplantation. Xeno-transplantation can be a solution to shortage of human sources. Immune isolation by microencapsulation of islet with alginate polymer could escape the immune injuries. Microencapsulated xenoislet transplantation is a one of the ideal strategies to cure the diabetes. Here, we introduce microencapsulation of islets for successful xenogenic islet transplantation. We achieved optimization of encapsulating condition. First, we demonstrated viability and insulin secreting capacity of encapsulated islets in vitro. We confirmed their ability of maintaining normoglycemia and escaping immune rejection after rat or porcine islet transplantation to diabetic mouse models.
김민정,박헌석,김지원,이은영,이마리,유영혜,강길손,박정규,윤건호 대한내분비학회 2021 Endocrinology and metabolism Vol.36 No.1
Background: The microencapsulation is an ideal solution to overcome immune rejection without immunosuppressive treatment. Poor biocompatibility and small molecular antigens secreted from encapsulated islets induce fibrosis infiltration. Therefore, the aims of this study were to improve the biocompatibility of microcapsules by dexamethasone coating and to verify its effect after xenogeneic transplantation in a streptozotocin-induced diabetes mice. Methods: Dexamethasone 21-phosphate (Dexa) was dissolved in 1% chitosan and was cross-linked with the alginate microcapsule surface. Insulin secretion and viability assays were performed 14 days after microencapsulation. Dexa-containing chitosan-coated alginate (Dexa-chitosan) or alginate microencapsulated porcine islets were transplanted into diabetic mice. The fibrosis infiltration score was calculated from the harvested microcapsules. The harvested microcapsules were stained with trichrome and for insulin and macrophages. Results: No significant differences in glucose-stimulated insulin secretion and islet viability were noted among naked, alginate, and Dexa-chitosan microencapsulated islets. After transplantation of microencapsulated porcine islets, nonfasting blood glucose were normalized in both the Dexa-chitosan and alginate groups until 231 days. The average glucose after transplantation were lower in the Dexa-chitosan group than the alginate group. Pericapsular fibrosis and inflammatory cell infiltration of microcapsules were significantly reduced in Dexa-chitosan compared with alginate microcapsules. Dithizone and insulin were positive in Dexa-chitosan capsules. Although fibrosis and macrophage infiltration was noted on the surface, some alginate microcapsules were stained with insulin. Conclusion: Dexa coating on microcapsules significantly suppressed the fibrotic reaction on the capsule surface after transplantation of xenogenic islets containing microcapsules without any harmful effects on the function and survival of the islets.
천경진,박헌석,이은영,김민정,유영혜,이마리,김지원,윤건호 대한당뇨병학회 2022 Diabetes and Metabolism Journal Vol.46 No.5
Background: Neonatal porcine pancreatic cell clusters (NPCCs) have been proposed as an alternative source of β cells for islet transplantation because of their low cost and growth potential after transplantation. However, the delayed glucose lowering effect due to the immaturity of NPCCs and immunologic rejection remain as a barrier to NPCC’s clinical application. Here, we demonstrate accelerated differentiation and immune-tolerant NPCCs by <i>in vitro</i> chemical treatment and microencapsulation.Methods: NPCCs isolated from 3-day-old piglets were cultured in F-10 media and then microencapsulated with alginate on day 5. Differentiation of NPCCs is facilitated by media supplemented with activin receptor-like kinase 5 inhibitor II, triiodothyronine and exendin-4 for 2 weeks. Marginal number of microencapsulated NPCCs to cure diabetes with and without differentiation were transplanted into diabetic mice and observed for 8 weeks.Results: The proportion of insulin-positive cells and insulin mRNA levels of NPCCs were significantly increased <i>in vitro</i> in the differentiated group compared with the undifferentiated group. Blood glucose levels decreased eventually after transplantation of microencapsulated NPCCs in diabetic mice and normalized after 7 weeks in the differentiated group. In addition, the differentiated group showed nearly normal glucose tolerance at 8 weeks after transplantation. In contrast, neither blood glucose levels nor glucose tolerance were improved in the undifferentiated group. Retrieved graft in the differentiated group showed greater insulin response to high glucose compared with the undifferentiated group.Conclusion: <i>in vitro</i> differentiation of microencapsulated immature NPCCs increased the proportion of insulin-positive cells and improved transplant efficacy in diabetic mice without immune rejection.
유영혜,함동식,박헌석,이마리,김지원,윤건호 대한당뇨병학회 2011 Diabetes and Metabolism Journal Vol.35 No.2
Background: A limitation in the number of insulin-producing pancreatic beta-cells is a special feature of diabetes. The identification of alternative sources for the induction of insulin-producing surrogate beta-cells is a matter of profound importance. PDX-1/VP16, BETA2/NeuroD, and MafA overexpression have been shown to influence the differentiation and proliferation of pancreatic stem cells. However, few studies have been conducted using adult animal pancreatic stem cells. Methods: Adult pig pancreatic cells were prepared from the non-endocrine fraction of adult pig pancreata. Porcine neonatal pancreas cell clusters (NPCCs) were prepared from neonatal pigs aged 1-2 days. The dispersed pancreatic cells were infected with PDX-1/VP16, BETA2/NeuroD, and MafA adenoviruses. After infection, these cells were transplanted under the kidney capsules of normoglycemic nude mice. Results: The adenovirus-mediated overexpression of PDX-1, BETA2/NeuroD and MafA induced insulin gene expression in NPCCs,but not in adult pig pancreatic cells. Immunocytochemistry revealed that the number of insulin-positive cells in NPCCs and adult pig pancreatic cells was approximately 2.6- and 1.1-fold greater than those in the green fluorescent protein control group,respectively. At four weeks after transplantation, the relative volume of insulin-positive cells in the grafts increased in the NPCCs,but not in the adult porcine pancreatic cells. Conclusion: These data indicate that PDX-1, BETA2/NeuroD, and MafA facilitate the beta-cell differentiation of NPCCs, but not adult pig pancreatic cells. Therefore PDX-1, BETA2/NeuroD, and MafA-induced NPCCs can be considered good sources for the induction of pancreatic beta-cells, and may also have some utility in the treatment of diabetes.
양혜경,함동식,박헌석,Marie Rhee,유영혜,김민정,김지원,이승환,홍태호,최병길,조재형,윤건호 대한의학회 2015 Journal of Korean medical science Vol.30 No.7
Pancreatic islet transplantation is a physiologically advantageous and minimally invasive procedure for the treatment of type 1 diabetes mellitus. Here, we describe the first reported case of successful allogeneic islet transplantation alone, using single-donor, marginal-dose islets in a Korean patient. A 59-yr-old patient with type 1 diabetes mellitus, who suffered from recurrent severe hypoglycemia, received 4,163 islet equivalents/kg from a single brain-death donor. Isolated islets were infused intraportally without any complications. The immunosuppressive regimen was based on the Edmonton protocol, but the maintenance dosage was reduced because of mucositis and leukopenia. Although insulin independence was not achieved, the patient showed stabilized blood glucose concentration, reduced insulin dosage and reversal of hypoglycemic unawareness, even with marginal dose of islets and reduced immunosuppressant. Islet transplantation may successfully improve endogenous insulin production and glycemic stability in subjects with type 1 diabetes mellitus.
수영강의 수질오탁과 그것이 광안리 해수용장에 미치는 영향에 대하여
원종훈,이배정,심무경,박헌석 한국수산학회 1979 한국수산과학회지 Vol.12 No.4
This research was conducted to evaluate the effects of polluted Suyeong River water on the water quality of Kwangan-Ri bathing beach. The quantity of pollutant loading of Suyeong River was determined in January 1979, and the directions of tidal currents and chemical constituents of the Suyeong Bay water were observed in May 1979. The results are as follows : The quantity of total pollutant loading which was discharged into Suyeong Bay is : 75.2ton/day; COD 96.9ton/day; SS 20.5ton/day; ammonia-nitrogen 12.4ton/day; nitrate-nitrogen 430kg/day; nitrite-nitrogen 85.1kg/day; phosphate-phosphorus 594kg/day and total heavey metals 3.01ton/day. Considering the tidal current, the polluted waters of Suyeong River flow off the Kwangan-Ri beach during the ebb tides, and flow into the Kwangan Ri beach during the flood tides. Consequently, the water quality of Kangan-Ri bathing beach is not suitable for bathing.