A finite element modeling of posterior atlantoaxial fixation and biomechanical analysis of C2 intralaminar screw fixation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The objective of this study was to use three-dimensional finite element (FE) models to analyze the stability and the biomechanics of two upper cervical fixation methods: the C2 intralaminar screw method and the C2 pedicle screw method.</p><p><b>METHODS</b>From computed tomography images, a nonlinear three-dimensional FE model from C0 (occiput) to C3 was developed with anatomic detail. The C2 intralaminar screw and the C2 pedicle screw systems were added to the model, in parallel to establish the interlaminar model and the pedicle model. The two models were operated with all possible states of motion and physiological loads to simulate normal movement.</p><p><b>RESULTS</b>Both the C2 intralaminar screw method and the C2 pedicle screw method significantly reduced motion compared with the intact model. There were no statistically significant differences between the two methods. The Von Mises stresses of the internal and external laminar walls were similar between the two methods. Stability was also similar.</p><p><b>CONCLUSIONS</b>The C2 intralaminar screw method can complement but cannot completely replace the C2 pedicle screw method. Clinicians would need to assess and decide which approach to adopt for the best therapeutic effect.</p>

Inhibition of arsenic trioxide for the capability of migration and invasion in Ewing' s sarcoma cell in vitro / 肿瘤研究与临床

ObjectiveTo investigate the effect of arsenic trioxide (As2O3) on the metastasis capability of Ewing's sarcoma ceils. MethodsMTT assays were performed to choose appropriate concentrations of As2O3 (＜ 2 μmol/L) for the experiments.Migration and invasion assays were performed to assess the effect of As2O3 on the metastasis of Ewing's sarcoma cells. Changes in matrix metalloproteinase(MMP)-9 expressions were detected by gel zymography assay and the phosphoinositide 3-kinase/AKT(PI3K-AKT)pathway was investigated using Western blot. ResultsThe amount of Ewing's sarcoma cells across basal membrane of Transwell in migration and invasion assay decreased gradually with the increase in As2O3 concentration. The average quantities of A-673 across the membrane after treatment by gradual concentrations accounted for 54.3 ％,49.0 ％ and 17.0 ％ of that of untreated group respectively in migration assay (F=112.78,P ＜ 0.01), while 52.7 ％, 32.3 ％ and 10.3 ％ in invasion assay(F =183.76, P ＜ 0.01). Similarly, the percentage of RD-ES was 46.0 ％,39.0 ％ and 8.0 ％ in migration assay (F =408.25,P ＜ 0.01) and 58.7 ％,22.3 ％ and 9.0 ％ in invasion assay (F =373.25, P ＜ 0.01)respectively. The difference had statistics significance.The expression of MMP-9 was suppressed by As2O3 treatment according to gel zymography assay.Western blot assay showed that PI3K-AKT pathway was inhibited and nuclear factor kappa B(NF-κB)was inactivated.ConclusionLow-concentration As2O3 may inhibit metastasis capability of Ewing's sarcoma cells.