The aim of this article is to study the effect of tumor necrosis factor alpha (TNF-α) on the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in keratoconus fibroblasts in vitro. Normal cornea and keratoconus fibroblasts were extracted using enzyme digestion method and were cultured in the medium containing TNF-α (0, 10 and 100 ng/mL). The expression of MMPs proteins in the supernatant of corneal fibroblasts and the expression of TIMPs in the normal cornea and keratoconus fibroblasts were detected by Western blot and real-time quantitative polymerase chain reaction respectively. The active form of MMP1 could be detected in the supernatant of keratoconus fibroblasts and upregulated by TNF-α. TNF-α could increase the protein expression of MMP2, MMP3, MMP9 in the supernatant of keratoconus fibroblasts and decrease the gene expression of TIMP1, TIMP2 in keratoconus fibroblasts. The increased MMPs and the decreased TIMPs can increase the degradation of the extracellular matrix. TNF-α may play an important role in the occurrence and development of keratoconus by regulating the expression of MMPs/TIMPs.
We developed a three-dimensional finite element model of the pelvis. According to Letournel methods, we established a pelvis model of T-shaped fracture with its three different fixation systems, i.e. double column reconstruction plates, anterior column plate combined with posterior column screws and anterior column plate combined with quadrilateral area screws. It was found that the pelvic model was effective and could be used to simulate the mechanical behavior of the pelvis. Three fixation systems had great therapeutic effect on the T-shaped fracture. All fixation systems could increase the stiffness of the model, decrease the stress concentration level and decrease the displacement difference along the fracture line. The quadrilateral area screws, which were drilled into cortical bone, could generate beneficial effect on the T-type fracture. Therefore, the third fixation system mentioned above (i.e. the anterior column plate combined with quadrilateral area screws) has the best biomechanical stability to the T-type fracture.