The aim of this research is to investigate the preparation method of valve membrane in transcatheter bio- prosthetic valve, and to study the effect of chemical modification and cutting technology to tensile property and suture force property of valve membrane. We carried out a series of processes to perform the tests, such as firstly to test the crosslinking degree of valve membrane using ninhydrin method, then to test the tensile property and suture force property by using Instron's biomechanicAl testing equipment, and then to observe the collagen fiber orientation in valve membrane using Instron's biomechanical testing equipment and using field emission scanning electron microscopy. The study indicated that after the chemical modification, the crosslinking degree, tensile strength and suture force strength increasing rate of valve membrane were 93.78% ± 3. 2%, (8.24 ± 0.79) MPa, 102%, respectively. The valve membrane had a better biomechanical property and would be expected to become valve membrane in transcatheter bioprosthesis valve.
Bioprosthesis ; Collagen ; chemistry ; Heart Valve Prosthesis ; Microscopy, Electron, Scanning ; Tensile Strength

Objective After the implantation,coronary stent is expected at least to keep its integrity and maintain the predicated function for over 10 years or 4e8 cycles under the pulsatile loading conditions,so the fatigue property of the stent should be evaluated.Method The finite method was used to analyze the stress distribution of different phases and evaluate the fatigue life according to Goodman criteria,meanwhile,the accelerated fatigue experiment was also performed.Results It can be concluded that the dangerous points are all but located in the lateral inner surface of stent curvature.Conclusions The results prove that the fatigue property can be simulated through the finite element analysis,which can provide the theoretical guidance for the stent design.

Magnesium stents have gained increasing interest as an ideal stent of future intervention. In order to study the deformation behavior of magnesium alloy stents in the interventional treatment, the finite element method was used to analysis the effects of different crimp and expansion dimensions on the mechanical properties (maximum stress, radial recoil rate, longitudinal shortening rate and radial strength). The results showed that crimping and expanding have a minimal influence on the stent radial strength. When the expansion size is same, the maximum equivalent stress and recoil rate decrease with the crimp size. When the crimp size is same, in contrast with the radial recoil rate, the maximum equivalent stress and longitudinal shortening rate increase with the expansion size. In addition the paper verified the radial strength-radial displacement curve obtained by FEM. Results are basically consistent, indicating the finite element method can efficiently provide researchers with reliable, high-quality design.
Alloys ; Finite Element Analysis ; Magnesium ; Stents

The finite element method was used for simulating the mechanical performance and fatigue safety of three different structures of Nitinol stent. According to the actual situation, after proposing reasonable assumptions and simplification, the geometry model and finite element model establishment, material mode selection and boundary condition setting are completed. The strain and fatigue life of different stent edges wide (omega) or strut angle (theta) are computed. The result can provide a valuable reference for the optimal design of stent.
Alloys ; Finite Element Analysis ; Prosthesis Design ; Stents

Objective To evaluate the flexibility and efficacy of the Willis covered stent in the treatment of distal internal carotid artery(DICA)aneurysms.Methods The study was approved by the anthors' institutional review board,and the research was conducted by the authors' institution and the MicroPort Medical Company(Shanghai,China).Thirty-one patients with 33 DICA aneurysms were considered for treatment with a Willis covered stent.The angiographic assessments were categorized as complete or incomplete occlusion.The data on technical Success,initial and final angiographic results,mortality,morbidity,and final clinical outcome were collected,and follow-up was performed at 1,3,6,and 12 months and yearly after the procedures.Results Navigation and deployment of the covered stents were succssfnl in 97.6%(41 of 42;95%confidence interval[CI]:93%,102%)of the attempted stent placement procedures.The initial angiographic results showed a complete occlusion in 23 patients with 25 aneurysms(of 32 aneurysms,78.1%[95%CI:63%,93%])and an incomplete occlusion in seven patients with seven aneurysms(21.9%).The angiographic follow-up(mean,14 months[95% CI:12,15 months])findings exhibited a complete occlusion in 27 patients with 29 aneurysms(of 31 aneurysms,93.5%[95%CI:84%,103%])and an incomplete occlusion in two aneurysms(6.5%),with a mild in-stent stenosis in two patients.The clinical follow-up(mean,27 months[95% CI:23,30 months])demonstrated that 15 patients experienced a full recovery and 14 patients improved.Conclusion The preliminary results demonstrate good flexibility and efficacy of the Willis covered stent in the treatment of DICA aneurysms in selected patients:longer follow-up and expanded clinical trials are needed.

Aim To evaluate the potency of anti-D. acutus venom IgY neutralizing the main activities of D. acutus venom.Methods After mixing the different a-mounts of IgY with snake venom and incubating togeth-er,the main activities of snake venom were assayed by biochemical methods.Results The in vitro assays in-dicated that anti-D.acutus venom IgY obviously neu-tralized the activities of PLA2 ,5′-nucleotidase,hyalu-ronidase,metalloprotease and serine proteinase (fi-brinogenase)in D.acutus venom.Mouse experiments showed that the ED50 value of IgY for mouse was 1 131.09 μg.Conclusion Anti-D.acutus venom IgY antibodies have good effects in neutralizing D.acutus venom without the toxicities themselves.

The character and application status of interventional thrombectomy devices for acute ischemic stroke (AIS) are briefly introduced and the development trend is also analyzed.
Brain Ischemia ; drug therapy ; surgery ; Humans ; Stroke ; drug therapy ; surgery ; Thrombectomy ; instrumentation ; Thrombolytic Therapy ; instrumentation

BACKGROUND: Our previous findings indicate that inflammation-activated bone marrow mesenchymal stem cell conditioned medium (MSC-CM) contribute to repairing the structure and function of the small intestine after radiation-induced acute intestinal injury. However, it is unclear whether the repair effect can be achieved by regulating small intestinal stem cells. OBJECTIVE: To investigate the effects of inflammation-activated bone marrow MSC-CM on the small intestinal epithelial stem cells after acute radiation-induced intestinal injury and to further discuss the repairing mechanism. METHODS: Bone marrow mesenchymal stem cells of Sprague-Dawley rats were separated, cultured and identified. Then, the bone marrow mesenchymal stem cells were co-cultured with normal or radiation-induced IEC-6 cell lines in the Transwell system for 24 hours. Inflammation-activated bone marrow mesenchymal stem cells were cultured alone for 48 hours. Non-activated MSC-CM (MSC-CMNOR) and MSC-CM under radiation-induced inflammatory condition (MSC-CMIR) were collected. Adult Sprague-Dawley rats (provided by the Experimental Center of Sun Yat-Sen University North Campus) were randomly divided into four groups with 20 rats in each group: control group, radiation group, radiation+MSC-CMNOR group and radiation+MSC-CMIR group. The rats in the latter three groups were exposed to one-off 14 Gy whole abdominal radiation to make a rat model of acute radiation-induced small intestinal injury. Three-day continuous administration beginning within 4 hours after successful modeling was given via the tail vein and intraperitoneal implantation of Alzet micro-osmotic pumps: EMEM-F12 (200 μL/d) for the radiation group, MSC-CMNOR for radiation+MSC-CMNOR group and MSC-CMIR for radiation+MSC-CMIR group. There was 2 mL of concentrated conditioned medium in the pump which was released at a constant rate of 10 μL/h into the abdominal cavity after implantation. Intestinal samples were collected at 1, 3, 5, 7 days after radiation for immunochemistry staining, western blot and qRT-PCR detection. RESULTS AND CONCLUSION: (1) On the 3rd day after radiation, Lgr5 positive cells, which were actively proliferating on the base of crypts, became significantly reduced compared with the normal control group, and there was nearly no existing Lgr5 positive cells. However, after infusion of MSC-CMIR, Lgr5 positive intestinal stem cells were significantly increased compared with the radiation group, while in the radiation+MSCNOR group, there was no significant increase in Lgr5 positive intestinal stem cells. (2) On the 3rd day after radiation injury, Bmi1 positive intestinal stem cells were almost invisible. After infusion of MSC-CMIR, Bmi1 positive intestinal stem cells increased significantly, and it was observed not only in the +4 cell position but also in the common position used to be Lgr5 stem cells, indicating that Bmi1 stem cells could differentiate into Lgr5 positive cells to act its repairing effect. (3) Western blot and qRT-PCR further confirmed that the radiation+MSC-CMIR group was significantly higher on the Lgr5 expression level than the radiation group and the radiation+MSC-CMNOR group, and it returned to the normal level on the 7th day after the continuous high expression level. The repair effect of radiation+MSC-CMNOR group was weaker, and only on the 7th day, the expression level of Lgr5 was statistically different from the radiation group. To conclude, inflammation-activated bone marrow MSC-CM exert a protective effect on the small intestinal epithelial stem cells after acute radiation-induced intestinal injury