The stiffness characteristics of hybrid Ilizarov fixators

The use of hybrid Ilizarov models around femoral area is gaining clinical popularity lately. Hybrid systems show different mechanical properties. The purpose of this report is to examine the stiffness characteristics of the C-arch and half-pins on the hybrid Ilizarov fixators. Eight models that included standard Ilizarov and hybrid models were applied to six femoral sawbones. The distal part of fixation was composed of a two-ring frame applied identically to all bones. The difference of the configuration was at the proximal part, where half-pins with or without C-arches were either added to the proximal two-ring frame OF replaced the proximal one- or two-ring frame. Osteotomy was performed in the femoral diaphysis and the bone was distracted 2 cm. The stability of the system was tested with the axial compression testing machine. Displacements between the adjacent fracture sides were measured with the video extensometer in three dimensions. We found that proximal half-pin applications alone had less stiffness, but half-pins with C-arch had more stiffness than the model including only half-pins. Additional half-pins onto one- OF two-ring frames had more longitudinal stiffness, but this system showed weak resistance against transverse displacement. (c) 2008 Elsevier Ltd. All rights reserved

Effects of simvastatin on matrix metalloproteinase regulation in IL-1 beta-induced SW1353 cells

The present study shows the basis for the anti-inflammatory effects of statins in interleukin 1 beta (IL-15) induced SW1353 chondrosarcoma cell-line. The cells were pre-treated with simvastatin (5 mu M, 10 mu M, and 50 mu M), followed by IL-1 beta (5 ng/mL) stimulation. Effects of simvastatin on cell viability and cytotoxicity of chondrocytes were measured with WST-1 and lactate dehydrogenase (LDH) assays, respectively. Under inflammatory conditions, in the absence/presence of simvastatin, the changes in matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-1 (TIMP-1) expression levels were examined. Expression levels of MMP-1, -2, -3, -9, -13, and TIMP-1 and -2 were examined by qPCR. MMP-1, -9, -13, TIMP-1, and -2 levels were also determined by Western blotting. Gelatin zymography was performed to analyze the released and intracellular MMP-2 and MMP-9 activity levels. The results showed that simvastatin downregulated the degradation related genes MMP3, MMP-13, MMP-2, MMP-9 and TIMP-2 in a dose-dependent manner