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( Jung Bok Lee ),( Sung Min Jeong ),( Kyoung Jun Kim ),( Dong Hyun Cho ),( Il Keun Kwon ),( In Chan Yoon ),( Kui Won Choi ),( Jun Kyo Francis Suh ),( Jae Hong Park ),( Yong Duk Park ),( Jong Hyuk Chun 한국조직공학·재생의학회 2009 조직공학과 재생의학 Vol.6 No.1
Dexamethasone(DEX), a synthetic steroidal anti-inflammatory drug, is an efficient and dependable drug that induces osteogenic differentiation. The aim of this study is to fabricate the DEX loaded PLGA nanofibers by electrospinning method. Adipose-derived stem cells(ADSCs) were seeded into the nanofiber and the sustained release of DEX from PLGA nanofiber scaffolds promoted their osteogenic differentiation. The properties of DEX loaded PLGA nanofiber scaffold were characterized by scanning electron microscopy(SEM) and the release kinetics of DEX from PLGA nanofibers in vitro(1 h to 14 days) was evaluated by high performed liquid chromatography(HPLC). To evaluate the cellular response of the ADSCs seeded onto DEX loaded PLGA nanofiber, we performed F-actin, cytotoxicity, alkaline phosphatase activity, alizarin red S, von Kossa staining and immunocytochemistry assays for osteogenic differentiation. DEX loaded PLGA nanofiber scaffold was observed to have sustained release in vitro during experimental periods. The cytotoxicity test of the DEX loaded PLGA nanofiber scaffold indicated there was almost no-toxic effects in regards to proliferation and differentiation of adiposederived stem cells(ADSCs) as compared with a control. Alkaline phosphatase activity and alizarin red S were more significantly increased after 14days with increased DEX concentration of PLGA nanofiber scaffold than with PLGA nanofiber only. Also, von Kossa staining results confirmed a larger area of calcium deposition with increased DEX concentration of PLGA nanofiber scaffold. We observed that osteocalcin was also increased with increasing DEX concentration. These results demonstrate that DEX acts as an osteogenic inductive factor, and increased DEX concentration promoted more osteogenic differentiation of ADSCs. In conclusion, DEX loaded PLGA nanofiber would be valuable tool for bone tissue regeneration.
JUNG, Won Kyo,KITCHEN, Newell R.,SUDDUTH, Kenneth A.,KREMER, Robert J. Society of the Science of Soil and Manure, Japan 2008 Soil science and plant nutrition Vol.54 No.6
Crop management has the potential to either enhance or degrade soil quality, which in turn impacts on crop production and the environment. Few studies have investigated how crop management affects soil quality over different landscape positions. The objective of the present study was to investigate how 12 years of annual cropping system (ACS) and conservation reserve program (CRP) practices impacted soil quality indicators at summit, backslope and footslope landscape positions of a claypan soil in north-central Missouri. Claypan soils are particularly poorly drained because of a restrictive high-clay subsoil layer and are vulnerable to high water erosion. Three replicates of four management systems were established in 1991 in a randomized complete block design, with landscape position as a split-block treatment. The management systems were investigated: (1) annual cropping system 1 (ACS1) was a mulch tillage (typically ≥ 30% of soil covered with residue after tillage operations) corn (Zea mays L.)?soybean (Glycine max (L.) Merr.) rotation system, (2) annual cropping system 2 (ACS2) was a no-till corn?soybean rotation system, (3) annual cropping system 3 (ACS3) was a no-till corn?soybean?wheat (Triticum aestivum L.) rotation system, with a cover crop following wheat, (4) CRP was a continuous cool-season grass and legume system. In 2002, soil cores (at depths of 0?7.5, 7.5?15 and 15?30 cm) were collected by landscape position and analyzed for physical, chemical and biological soil quality properties. No interactions were observed between landscape and crop management. Relative to management effects, soil organic carbon (SOC) significantly increased with 12 years of CRP management, but not with the other management systems. At the 0?7.5-cm soil depth in the CRP system, SOC increased over this period by 33% and soil total nitrogen storage increased by 34%. Soil aggregate stability was approximately 40% higher in the no-till management systems (ACS2 and ACS3) than in the tilled system (ACS1). Soil aggregation under CRP management was more than double that of the three grain-cropping systems. Soil bulk density at the shallow sampling depth was greater in ACS3 than in ACS1 and ACS2. In contrast to studies on other soil types, these results indicate only minor changes to claypan soil quality after 12 years of no-till management. The landscape had minor effects on the soil properties. Of note, SOC was significantly lower in the 7.5?15-cm soil depth at the footslope compared with the other landscape positions. We attribute this to wetter and more humid conditions at this position and extended periods of high microbial activity and SOC mineralization. We conclude that claypan soils degraded by historical cropping practices will benefit most from the adoption of CRP or CRP-like management.