Tripterygium wilfordii polysaccharide induces differentiation of pancreatic stem cells into islet-like cell clusters / 中国组织工程研究

BACKGROUND: Inadequate sources of islet cells mean that islet cell transplantation for diabetes cannot meet the clinical demand.Therefore,in vitro induction of pancreatic stem cells to differentiate into islets has become a focus of research. OBJECTIVE:To study the effect of Tripterygium wilfordii polysaccharides on the differentiation of pancreatic stem cells from islets in mice, so as to explore the effect of traditional Chinese medicine on the differentiation of pancreatic stem cells into pancreatic beta cells. METHODS:Tripterygium wilfordii polysaccharide was used to induce the differentiation of purified mouse pancreatic stem cells into islets in vitro.The islet-like cell clusters then underwent morphologic observation, dithizone (DTZ) staining, and western blot analysis. RESULTS AND CONCLUSION: Cell morphology, cell growth characteristics and immunocytochemical staining showed that mouse pancreatic stem cells were obtained.They were induced by Tripterygium wilfordii polysaccharide into spherical islet-like structures, which had a spindly pedicle connected with the bottom of the culture flask, and were DTZ-stained to iron red. Western blot assay detected β-cytokine proteins in the islet-like cell clusters. These findings confirm that mouse pancreatic stem cells can be induced to differentiate into islet-like cell clusters containing β cells in vitro by Tripterygium wilfordii polysaccharide.

Effects of strut numbers on biomechanical properties of Z-shaped stent-grafts / 医用生物力学

Objective To analyze the influence from strut numbers on biomechanical properties of Z-shaped stentgrafts,especially on their radial support performance and flexibility,so as to provide theoretical support for the design and clinical selection of Z-shaped stent-grafts.Methods Z-shaped stent-grafts with 5,8,10,12 struts were established by finite element method to simulate the process of compression and bending behavior.Radial displacements were applied on surface of the stent-graft and opposite rotations were applied around the z-axis,until a bending angle of 40° was reached.Then parameters such as stent stress,radial support force,strains in graft,cross-section deflection,bending torque were extracted to evaluate the performance of different stentgrafts.Results Compared with stent-grafts with more strut numbers,5-strut stent-graft showed a better radial support performance with the maximum radial force during compression,and it also generated the smallest 68 N · mm torque and 67.5％ cross-section deflection.The tensile strain in graft of 5-strut stent-graft during the process of bending was relatively smaller.Conclusions The strut number of Z-shaped stent-grafts has a significant influence on biomechanical properties of the stent-grafts.Especially the Z-shaped stent-graft with relatively fewer strut numbers shows an advantage in evaluating radial support performance and flexibility such as the bending torque and the cross-section deflection,and is more suitable to be anchored and fit to the tortuous blood vessel,which will play a positive role in decreasing the complication such as endoleaks and thrombosis.The research findings can guide structure design of Z-shaped stent-grafts and optimal selection for surgery.

Effects of strut numbers on biomechanical properties of Z-shaped stent-grafts / 医用生物力学

Objective To analyze the influence from strut numbers on biomechanical properties of Z-shaped stentgrafts,especially on their radial support performance and flexibility,so as to provide theoretical support for the design and clinical selection of Z-shaped stent-grafts.Methods Z-shaped stent-grafts with 5,8,10,12 struts were established by finite element method to simulate the process of compression and bending behavior.Radial displacements were applied on surface of the stent-graft and opposite rotations were applied around the z-axis,until a bending angle of 40° was reached.Then parameters such as stent stress,radial support force,strains in graft,cross-section deflection,bending torque were extracted to evaluate the performance of different stentgrafts.Results Compared with stent-grafts with more strut numbers,5-strut stent-graft showed a better radial support performance with the maximum radial force during compression,and it also generated the smallest 68 N · mm torque and 67.5％ cross-section deflection.The tensile strain in graft of 5-strut stent-graft during the process of bending was relatively smaller.Conclusions The strut number of Z-shaped stent-grafts has a significant influence on biomechanical properties of the stent-grafts.Especially the Z-shaped stent-graft with relatively fewer strut numbers shows an advantage in evaluating radial support performance and flexibility such as the bending torque and the cross-section deflection,and is more suitable to be anchored and fit to the tortuous blood vessel,which will play a positive role in decreasing the complication such as endoleaks and thrombosis.The research findings can guide structure design of Z-shaped stent-grafts and optimal selection for surgery.

Effects of strut numbers on biomechanical properties of Z-shaped stent-grafts / 医用生物力学

Objective To analyze the influence from strut numbers on biomechanical properties of Z-shaped stent-grafts, especially on their radial support performance and flexibility, so as to provide theoretical support for the design and clinical selection of Z-shaped stent-grafts. Methods Z-shaped stent-grafts with 5, 8, 10, 12 struts were established by finite element method to simulate the process of compression and bending behavior. Radial displacements were applied on surface of the stent-graft and opposite rotations were applied around the z-axis, until a bending angle of 40°was reached. Then parameters such as stent stress, radial support force, strains in graft, cross-section deflection, bending torque were extracted to evaluate the performance of different stent-grafts. Results Compared with stent-grafts with more strut numbers, 5-strut stent-graft showed a better radial support performance with the maximum radial force during compression, and it also generated the smallest 68 N•mm torque and 67.5% cross-section deflection. The tensile strain in graft of 5-strut stent-graft during the process of bending was relatively smaller. Conclusions The struts number of Z-shaped stent-grafts has a significant influence on biomechanical properties of the stent-grafts. Especially the Z-shaped stent-graft with relatively fewer strut numbers shows an advantage in evaluating radial support performance and flexibility such as the bending torque and the cross-section deflection, and is more suitable to be anchored and fit to the tortuous blood vessel, which will play a positive role in decreasing the complication such as endoleaks and thrombosis. The research findings can guide structure design of Z-shaped stent-grafts and the operation to make an optimal selection.

Biomechanical comparison for two types of nitinol stent-grafts / 医用生物力学

Objective To study biomechanical properties of two types of cylindrical nitinol stent-grafts under working condition of self-expanding, full deployment and bending, and analyze effects of structural change on biomechanical indexes of the grafts by numerical simulation methods. MethodsFirstly, the finite element models of two annular stent-grafts (i.e. stent-graft Ⅰ, stent graft Ⅱ, and a connecting rod was added to each stent unit of stent-graft Ⅱ for reinforcement) and target vessels were built. The stent-graft was transported to target vessel by delivery sheath, which was then removed to self-expand the stent-graft, and the contact between the vessel and the stent-graft was established. Secondly, the arterial pressure of 6.65-19.95 kPa (50-150 mmHg) was applied to inner surface of the stent-graft when the stent graft was fully deployed. Thirdly, the angular displacement was applied to both ends of the stent-graft to bend and deform the stent-graft. Finally, the maximum Von Mises stress (VMS) of the deformed vessel, the maximum principal strain (MPS), the maximum VMS and structural changes of the stent-graft were analyzed. ResultsFor both the stent-graft Ⅰ and Ⅱ, when they were self-expanding, the maximum VMS on the vessel was 0.349 MPa and 0.371 MPa, respectively; when they were fully deployed, the mean strain was 0.086% and 0.053%, the alternating strain was 0.049% and 0.027%, the maximum VMS on the membrane was 2.098 MPa and 2.430 MPa, respectively; when they were bent, the MPS was 0.069% and 0.101%, respectively, with more serious deformation on stent-graft Ⅰ. ConclusionsThe strain and stress of two stent-grafts under each working condition were less than their own material yielding limit. Stent-graft Ⅱ showed larger radial force in self-expanding, smaller strain under arterial pressure and better flexibility in bending deformation due to its connecting rod between each stent unit. These research results would provide an analysis method for structure design and material selection of the stent-graft, as well as a more intuitive and accurate technique guidance for intervention operation of the stent-graft in clinic.

Correlation of CKP and VEGF expression and microvessel density to spiral CT manifestations of thymoma / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the correlation of cytokeratin pan (CKP), vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) to spiral CT manifestations of thymoma.</p><p><b>METHODS</b>Eighty-four thymoma patients were underwent spiral CT examination, and 40 of the patients also had enhanced CT examination. All the CT findings were carefully reviewed to analyze their correlation to the expressions of CKP, VEGF and MVD.</p><p><b>RESULTS</b>The enhancement on spiral CT images increased with the levels of VEGF expression and MVD counting (P<0.01). Significant correlations were observed between VEGF expression, MVD counting and such spiral CT findings as lobular contours, cusp-like or sawtooth-like margins and tumor invasions of the pleural membrane, pericardium and great vessels (P<0.05). CKP expression showed no obvious correlation to these findings by spiral CT.</p><p><b>CONCLUSION</b>Spiral CT can reflect the pathological characteristics of thymoma, and may serve as a noninvasive modality for preoperative evaluation of thymoma.</p>

Modification of the right subclavian vein catheterization and its anatomic basis and techniques / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Several million subclavian-vein catheters are placed in patients each year to enable caregivers to administer chemotherapy, total parenteral nutrition, or long-term antibiotics or to manage preoperative fluids. Subclavian venipuncture requires the position of a deep vein to be identified with only surface landmarks. But the traditional right subclavian vein (RSV) catheterization (primitive procedures) is not the answer for all patients. The precise location of the vein is not known, and it is important to select the most appropriate method to achieve central venous access safely in any given patient. To modify the primitive procedures of the RSV catheterization for greater success and reduce the complications, anatomic studies and ultrasonography were conducted and clinical applications were validated.</p><p><b>METHODS</b>Anatomical observation and measurement of the RSV and its adjacent structures were performed on 20 adult cadavers according to modified procedures. The RSV catheterization of 2900 cases was carried out by the modified procedure, 500 of these cases were observed by ultrasonography after the operation.</p><p><b>RESULTS</b>The anatomical studies and clinical application showed that the insertion point differs from the bodily form of fatness or leptosome. The clinical data revealed that in the 2900 cases which were performed with the modified approach, the success rate was 98.90% (2868 cases), the failure rate was 1.10% (32 cases), and the complication rate is 0.79% (23 cases), and the catheterization time is (31.2 +/- 10.5) minutes. Five hundred and sixty cases of the RSV catheterization were carried out by the recommended insertion procedure; the results were compared with the modified approach and the traditional approach. The successful rate of the traditional approach was 73.0%, of which the complication rate was 6.1%; the two approaches were significantly different (successful rate: chi(2) = 626.642, P < 0.01; complication rate: chi(2) = 80.708, P< 0.01).</p><p><b>CONCLUSIONS</b>The modified RSV catheterization is characterized with a higher success rate and less complications, and the insertion procedure differs from the bodily form of fatness or leptosome.</p>

The experimental study of the effect of dexamethasone,lidocaine and contrast medium on the activity of collagenase / 介入放射学杂志

Objective To study the effects of hormone,anesthetie and contrast medium on the activities of collagenase lysis.Methods Nuclear tissues were divided into equal amount for different groups and same units of collagenase were used for the lysis.The only difference in the control group from experimental groups was that there were no dexamethasone,lidocaine or omnipaque but existing in experimental groups.Twenty four hours later,the concentrations of the hydroxyproline were determined in different groups and the data were analyzed by statistical software with computer.Results 1.The concentrations of hydroxyproline in the dexamcthasone group,lidocaine group and omnipaque group were significantly lower than that of control group,especially that of lidocaine group,P value was＜0.05 or 0.01.2. The concentrations of hydroxyproline in the dexamethasone+lidocaine group,dexamethasone+omnipaque group,lidocaine+omnipaque group and dexamethasone+lidocaine+omnipaque group were significantly lower than that of control group;and simultaneously lower in dexamethasone group,lidocaine group,omnipaque group respectively;P value was also＜0.05 or 0.01.Conclusion Dexamethasone,lidocaine and omnipaque can individually inhibit the activity of collagenase at different degrees,so they shouldn't be used together with collagenase in treating the lumber disc herniation.