1,721,046 research outputs found
Reactive Oxygen Scavenger Effect of Pyrimidines, Benzotriazoles and Related Compounds
No full textFree radicals and reactive oxygen metabolites have been implicated as important pathologic mediators in many clinical disorders and diseases. An efficient method of detecting the free radical scavenger effect is through xanthine oxidase (XO) inhibition. The inhibition efficiency on XO has been detected as the rate of uric acid production, which has max 295 nm. Sulfasalazine showed potent inhibiting activity on XO (IC50 = 25.11muM ; Ki = 50.88muM) and induced a mixed-type (noncompetitive-uncompetitive) inhibition of the substrate xanthine. 2-mercapto-4(3H)- quinazolinone (16) and 2-mercaptopyrimidine (4) displayed inhibiting activity on XO with IC 50 = 98.71 and 136.14muM, while apparent inhibition constants (K) were 158 .38 and 62. 46muM respectively. However benzotriazoles showed weak inhibitory effect. The spin-trapping method with 5,5- dimethyl-1-pyrroline N-oxide (DMPO) by electron spin resonance (ESR) detected the presence of O2(-) and OH. It showed that the percentage inhibition for formation of DMPO- OOH for 2-mercapto-pyrimidine and sulfasalazine were 64.78 and 35.09 , but for hydroxylation were 49.51, 38.55, 37.29 for 2-mercapto-4(3H)- quinazolinone, sulfasalazine and 2- mercaptopyrimidine at 500muM, respectively
Optimum Intensities of Ultrasound for Pge(2) Secretion and Growth of Osteoblasts
No full textThis study compared the effects of different intensity ultrasound (US) on osteoblasts in the far-field model with effects of the near-field model from the literature, to understand the relations between prostaglandin E-2 (PGE(2)) and osteoblast growth. We used an in vitro model to investigate the effects of 1-MHz, pulsed 1:4, and five different spatial-average temporal-peak intensity (150, 300, 600, 1200 and 2400 mW/cm(2)) US stimulations in far-field exposure (240 mm) on osteoblasts for 15 min. Optimum intensity in this study was 600 mW/cm(2), and cell density and PGE (2) secretion could be significantly stimulated at this intensity. This research may indicate that the growth of osteoblasts by US stimulation was , at least partly, due to increases in the synthesis and secretion of PGE( 2). This well-controlled model can lead to further research on the biologic mechanisms for US. (C) 2002 World Federation for Ultrasound in Medicine Biology
Comparsion of Open Vs Closed Intramedullary Nailing of Femur by Utilizing Interlocking Nail
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Prevascularized bone graft cultured in sintered porous β-Ca2P2O7 with 5 wt% Na4P2O7·10H2O addition ceramic chamber
No full textThe Effect of Ca/P Concentration and Temperature of Simulated Body Fluid on the Growth of Hydroxyapatite Coating on Alkali-Treated 316l Stainless Steel
No full text316L-SS is one of the important materials both in orthopaedics and dentistry for bone screw/plate, intra- medullary rod. fixation wire, HIP joint, and knee joint. However. the biocompatibility and bone-bonding ability troubled researches for years. In the study, a simple chemical method was tried so as to establish and induce a bioactive HA layer on the surface of 316L stainless steel. When the metallic substrates treated with 10 M NaOH aqueous solution and Subsequently heated at 600 C. a thin sodium chromium oxide layer was formed on the surfaces as the linking layer for HA and 316L-SS. After 316L-SS treated with alkali solution, it would soak into a simulated body fluid with higher concentration of calcium and phosphorous ions to increase the possibility Of nucleation of HA. However. the iron oxide and iron chromium oxides were formed on the surface when calcium and phosphorous ions increased. This resulted in loosening the HA layer. When the alkali-treated 316L-SS was soaked into SBF tit a temperature of 80degreesC, it could form a dense and uniform bone-like hydroxyapatite la,,er oil the surface. In the research, the mechanism of the formation of sodium chromium oxide and HA would also be described by the analysis of X-ray diffractometer, scanning electron microscope, energy-dispersion spectrophotometer. and Fourier transformation infrared. (C) 2002 Elsevier Science Ltd. All rights reserved
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