Mechanical analysis on treatment of vertebral artery stenosis by stents with different links / 医用生物力学

Objective To investigate the mechanical effect of stents with different links on the treatment of vertebral artery stenosis, and provide scientific guidelines for the design of stent structure and clinical procedure of stenting intervention. Methods Models of three kinds of stents with different types of links (namely, L-stent, V-stent and S-stent according to the shape of links) and vertebral artery with stenosis were established by using Pro/Engineering, then the same boundary conditions were exerted on the three models to simulate the stent deployed in the vertebral artery by finite element analysis using ABAQUS. Results Compared with L-stent and V-stent, S-stent had a better compliance, generating smaller stress in the arterial wall, causing relatively weak vascular straightening. Due to smaller stress and axial shortening generated in the stent strut, S-stent made less lesion on the arterial wall. Conclusions The therapeutic effect of S-stent is the best among the three kinds of stents, which could reduce in-stent-restenosis, and has good prospect in clinical application.

Hemodynamic simulation of vertebral artery stenosis treated by stents with different links / 医用生物力学

Objective To investigate the hemodynamic effect of stents with different types of links on treating vertebral artery stenosis, and provide scientific guidelines for the design of stent structure and the clinical procedure of stent intervention. Methods Models of vertebral artery with stenosis and three kinds of stents with different types of links (named as L-stent, V-stent and S-stentaccording to the shapes) were constructed by using Pro/Engineering. The expansions of these stents in the stenotic vertebral artery were simulated using ABAQUS, and three finite element models of the stented vertebral artery were then established for fluid flow analysis, and hemodynamic simulation was performed using ANSYS-CFX. Results Compared with V-link and S-link stent, L-link stent had smaller area of low wall shear stress distributions and smaller blood stagnation area. Conclusions With better hemodynamic effect, L-stent can potentially reduce the possibility of in-stent restenosis and provide scientific references for the choice of stent, the design of stent structure and surgical planning of stent intervention.

Identification of human small supernumerary marker chromosomes and discussion of its research value / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the origin of human small supernumerary marker chromosomes (sSMCs) using fluorescent in situ hybridization (FISH) combined with G-banding karyotype analysis, and to discuss their mechanisms of formation and research value.</p><p><b>METHODS</b>Cep-FISH and SubcenM-FISH were used to analyze sSMCs in 3 patients for whom the result of G-banding was 47,XN,+mar.</p><p><b>RESULTS</b>The FISH result of case 1 was 47,XY,+mar.ish inv dup(22)(q11.1)(D22Z4++,D14/22Z1+, RP11-172D7-). The marker has formed exclusively by heterochromatin. A boy was delivered later with no apparent clinical abnormalities. The FISH result of case 2 was 47,XX,+mar.ish r(10)(p11.2q11.2) (cep10+, RP11-232C13+, RP11-178A10+)[25]/46,XX[10]. The marker has formed by heterochromatin and nearby centromere. A girl was delivered later with no clinical abnormalities. The FISH result of case 3 was 47,XY,+mar.ish inv dup(22)(q11.1)(D22Z4+,D14/22Z1+). The marker has also formed exclusively by euchromatin. Fetal abnormalities were detected by type B ultrasonography, but were not necessarily related with the marker.</p><p><b>CONCLUSION</b>The diversity of sSMCs has posed a great challenge for prenatal diagnosis. Identification of sSMCs will require combined karyotype analysis and FISH or other molecular techniques such as microarray based comparative genomic hybridization or sequencing. For its specific structure, the sSMCs may also provide a valuable tool for gene mapping, heterochromatin research and gene therapy.</p>

Fluid structure interaction analysis based on patient-specific internal carotid artery aneurysm model / 医用生物力学

Objective To analyze the distribution characteristics of blood flow and wall shear stress with the consideration of elasticity of the artery wall and to investigate the biomechanical factors inducing aneurismal rupture. Methods The three-dimensional patient-specific internal carotid artery aneurysm model was constructed based on two-dimensional medical scan images. The artery wall model was created based on the statistical data of human body. According to the condition of the pulsatile blood flow in human body, hemodynamics in internal carotid aneurysm with fluid structure interaction was simulated using finite volume method and finite element method. Results An obvious vortex flow in aneurismal cavity was found with the direction unchanged during a cardiac cycle. There was a region at the aneurismal neck and aneurismal dome where the value of wall shear stress was relatively high. It also found two regions in the aneurismal neck and the aneurismal dome where the value of Von Mises Stress reached the maximum locally. In view of the material strength, it should be easy to have aneurismal rupture in these areas. Conclusions The distribution characteristics of vascular wall stress can be obtained by the calculation of fluid structure interaction to further predict the possible position of aneurismal rupture.

Effect on aneurysmal pressure after stent intervention treatment for aneurysm accompanied by stenosis / 医用生物力学

Objective To investigate the effect on aneurysmal pressure after stent intervention treatment for aneurysm accompanied by stenosis. Methods Computational fluid dynamics (CFD) analyses were carried out to make comparative study on aneurysm models with and without stenosis. Three models (M1, M2, M3) were constructed to compare the pressure variations. M1 was the aneurysm model with no stenosis and no stent, M2 was forming from M1 model with a preaneurysm stenosis, and M3 was the M2 model with stent implantation at the place of the aneurysm. Results For comparison between M2 and M1, pressure increase in the aneurismal sac caused by a mild stenosis (50%) was about 1.399 9 kPa(10.3 mmHg) with the peak systole, and the average pressure increase in a cardiac cycle was about 0.572 kPa(4.3 mmHg). For comparison between M2 and M3, pressure increase in the aneurismal sac was about 1.037 kPa(7.8 mmHg) at peak systole in a cardiac cycle, and the average pressure increase in the aneurismal sac in a cardiac cycle was about 0.399 kPa(3 mmHg). Conclusions A mild stenosis could not result in the sharp pressure increase with stent intervention applied to the treatment of aneurysm accompanied by stenosis harbored on a tortuous intracranial artery. The geometry of the parent vessel and its aneurysmal/stenotic diseases do have influence on the pressure variation at the place of aneurysm.

Numerical research of hemodynamic effects on internal carotid aneurysm with five types of stents / 医用生物力学

Objective To investigate effects of endovascular stents with different structures and wire cross section shapes on the treatment of internal carotid aneurysm and its influence on hemodynamics and flexibility. Method Based on the same model of internal carotid aneurysm, five models with different stent intervention treatment were constructed, which had different stent structions or wire cross section shapes while their porosity rates were approximately the same. Numerical simulations were performed using finite volume method to get quantitative information of biomechanics. Results Among the five models, the mean flow rate in aneurismal cavity decreased maximally in the model with stent of rectangular cross section. Wall shear stress in aneurismal dome and aneurismal neck were found to decrease much more in models with circular cross section and rectangular spiral stent. The flexibility of mesh stent was far better than that of the spiral stent. Conclusions Mesh stent with rectangular cross section has better biomechanical influence on the treatment of internal carotid aneurysm. These findings may help clinicians to select a proper stent when treating arterial aneurysm.

Progress in mechanism of microcystin toxicity / 浙江大学学报·医学版

Microcystin is one of the monocyclic heptapeptides produced primarily by microcystis aeruginosa. Recent studies suggest that microcystin can induce cell apoptosis, as well as oxidative stress and mitochondrial alteration. Studies also indicate that Bcl-2 family and p53 may play an important role in the apoptosis induced by microcystin.

Expression of P53 and Bax in rat liver induced by microcystin LR in vivo / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To examine the expression of P53, Bcl-2 and Bax proteins in rat liver after exposed to microcystin LR.</p><p><b>METHODS</b>SD rats received microsystin LR by gastric perfusion. The expression of P53, Bax and Bcl-2 in liver was detected by Western blot.</p><p><b>RESULTS</b>The expression of P53 and Bax in each treatment group increased significantly compared with that in control group(P<0.05), with the exception of 0.1 microg/kg LR exposure group. Moreover, with exposure levels increasing the expression of P53 and Bax increased gradually; while no changes of the expression of Bcl-2 were observed.</p><p><b>CONCLUSION</b>P53 and Bax may play important roles in microcystin LR induced apoptosis, but Bcl-2 seems not be involved in this process.</p>