조경설계 교육을 위한 VRML-WEB 활용 연구

학위논문(석사)--서울대학교 대학원 :생태조경학과,2003.Maste

통계와 규칙에 기반한 2단계 한국어 품사 태깅 시스템

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Growth factor-free cultured rat bone marrow derived mesenchymal stem cells towards hepatic progenitor cell differentiation

Induction of mesenchymal stem cells (MSCs) differentiation by growth factors is not likely to be acceptable for clinical application. In this study, MSCs and hepatocytes isolated from male Sprague-Dawley rats were indirectly co-cultured by sharing media, without any growth factor, for 14 days. Differentiation was investigated by detection of hepatic markers, albumin, α-fetoprotein (AFP), cytokeratin-18 (CK18), and bile ductal epithelial cell marker cytokeratin-19 (CK19) on reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence staining, and Western blot. Periodic acid-schiff (PAS) staining, low density lipoproteins (LDL) uptake analysis, and urea assay were performed to detect metabolic activities of differentiated cells. MSCs in co-culture group showed positive expression for albumin, AFP, and CK19, but little for CK18. Data indicates that co-cultured MSCs were differentiated into oval cell stage, the hepatic progenitor, but not directly toward complete hepatocytes. Our finding suggests that indirect co-culture system has potential to generate regenerative hepatocytes by hepatic progenitor cells differentiated from MSCsope

A polyethylene glycol grafted bi-layered polyurethane scaffold: preliminary study of a new candidate prosthesis for repair of a partial tracheal defect

The purpose of this study was to develop an artificial prosthesis for use in the reconstruction of a tracheal defect due to trauma, malignancy, stenosis, or other causes. Bi-layered porous-dense film polyurethane (PU) was manufactured for the main framework. Polyethylene glycol (PEG) was grafted onto the inner surface of the PU scaffold to act as a surfactant. The scaffold was transplanted into three beagles. An endoscopic examination was performed for the evaluation of the formation granulation tissue, to evaluate the status of the respiratory mucosa and the amount of crust at 1, 4, 8, and 12 weeks after surgery. A histological examination was also performed at 4, 8, and 12 weeks after surgery. All three beagles studied survived to the expected date. The endoscopic examination showed formation of granulation tissue; the crust was not very severe and the circular tracheal framework was well preserved. The histological examination showed that a large amount of fibrous tissue had grown through the pores of the porous scaffold. Pseudostratified columnar ciliated mucosa was also noted on the surface of scaffold, as visualized by scanning electron microscopy. The use of a bi-layered polyethylene grafted polyurethane scaffold is a good candidate prosthesis for tracheal reconstructionope