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Objective To develop an in vitro vascular tensile stress loading device and study the distributions of tensile stress and tensile strain on the elastic basement membrane (silicone sheet). Method The in vitro vascular tensile stress loading device which simulated the human hemodynamic environment was developed based on the elastic basement membrane deformation loading technology. The images of grid points before and after the stretch of the silicon sheet were recorded by camera and transformed into the digital images. The characteristics for the location of the grid points were calculated by using Matlab software, so as to obtain the strain distribution on the silicon sheet. Experiments were conducted on the silicon sheet by using the universal material testing machine, so as to calculate the mechanical parameters of the silicon sheet. The finite element model was established according to the mechanical parameters, and the distribution of tensile stress and tensile strain on the silicon sheet was simulated and calculated. The experimental results and simulative results were then compared. Results The finite element results were basically in accordance with the experimental results. The maximum value of tensile stress and tensile strain appeared on the loading point, while the stress and strain in intermediate area were comparatively homogeneous. 60% of the intermediate area in the silicone sheet could be regarded as homogeneous strain fields Conclusions The research finding can provide experimental techniques for the dynamic culture of vascular endothelial cells and the research on cell mechanics in the future.
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Objective To study the effect of myocardial bridge oppression on blood flow, positive pressure, circumferential stress and shear stress of the coronary artery. Methods The original myocardial bridge simulative device was greatly improved to be able to measure multi-hemodynamic parameters, such as normal stress, circumferential stress and shear stress, so as to exactly simulate real blood dynamics environment with the common effect of several stresses, and comprehensively investigate the relationship between hemodynamics and atherosclerosis of mural coronary artery under the combined effects of several stresses. Results The results from the myocardial bridge simulative device indicated that the hemodynamic abnormalities were mainly located in the proximal end of mural coronary artery, and the mean and oscillation values of normal stress at the proximal end were increased by 27.8% and 139%, respectively, showing a significant increase with the intensification of myocardial bridge oppression. Conclusions It is myocardial oppression that causes the hemodynamic abnormity of proximal coronary artery, which is quite important for understanding the hemodynamic mechanism of coronary atherosclerotic diseases and valuable for studying pathological effects and treatments of the myocardial bridge in clinic.
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The aim of this study was to investigate whether several clinical variables can affect the pregnancy rate of intracervical insemination [ICI] using cryopreserved donor spermatozoa. In this retrospective study, age, years of infertility, cervicitis, urinary luteinizing hormone [LH] surge, insemination number, uterus position, endometrial thickness and morphology, maximal follicle diameter, and the number of dominant follicles on the day of human chorionic gonadotropin [HCG] administration were retrospectively analyzed in 501 women who underwent their first ICI cycle using cryopreserved donor spermatozoa. Increased age, length of infertility [>5 years], retroverted uterine position, and endometrial thickness [<7 mm or >14 mm] were associated with lower rates of pregnancy. In older women with infertile periods longer than five years, especially those with a retroverted uterus, intrauterine insemination [IUI] combined with ovarian stimulation should be recommended. In vitro fertilization with donor spermatozoa [IVFD] should be offered earlier to achieve a much higher success rate.