ABSTRACT
Objective In order to avoid early restenosis after drug-eluting stent (DES) implantation, the retrievable structure of the NiTi alloy stent and its biomechanical analysis were studied. Methods The geometric models of the retrievable vascular stent and the retrieval system were established. The retrieval part of the stent consisted of four symmetrically distributed tendons, which were designed as circular meshes. The distribution of the maximum strain during stent compression and its uniformity during compression and self-expansion were analyzed, and the simulation experiments of the retrieval process were also performed. Results The maximum strain of the stent was 3.7% and the index of non-uniformity (INU) was 0.62% when the stent was compressed to the minimum size. While the IBU was 1.31% after the self-expansion process completed. The maximum strain was 1.2% when half of the stent was retrieved into the outer sheath. Conclusions The stent could be safely and successfully retrieved into the outer sheath as the strain was within the bearable range of the material and the compression and self-expansion process was relatively uniform. The research findings provide important references for structural design, biomechanical analysis and potential clinical applications of the novel retrievable vascular stent.
ABSTRACT
OBJECTIVE:To investigate the effects of saikosaponin-d(SSd) on tissue plasminogen activator(TPA),plasminogen activator inhibitor(PAI),malonaldehyde(MDA) and NO in rats with liver fibrosis induced by dimethylnitrosamine(DMN).METHODS:Eighteen SD healthy rats were randomized to control group(NS ip qd for 4 weeks),model group(10mg? kg-1 DMN ip 3 times per week for 4 weeks) and SSd-treated group(10mg? kg-1 DMN ip 3 times per week + SSd 1.8 mg? kg-1 ip for 28 consecutive days).All rats were killed 1h after the last time of administration,blood samples were taken from abdominal aorta and liver samples were taken for the observation of pathology and detection of indices of TPA,PAI,MDA and NO etc.RESULTS:SSd could lessen the degree of liver fibrosis and improve the fibrinolytic activities of TPA and PAI,meanwhile,it showed clearance effect on MDA and marked protective effect on hepatic cells.There were significant differences between SSd-treated group and the model group.CONCLUSION:SSd exhibited protective function on experimental hepatic fibrosis in rats,which may be attributed to the improving of fibrinolytic activity,eliminating of lipid peroxidation and enhancing of NO level.