Abstract:Objective To investigate the effects of shear stress on integrin β 1 and F-actin in endothelial cells (EC) co-cultured with vascular smooth muscle cells ( VSMC ) . Methods The double-immuno-fluoro-cytochemistry, laser confocal scanning microscopy and image analysis methods were used in the study. One group of EC was treated with shear stress 2Pa for 1h?6h?12h and 24h. The other group was maintained under static conditions as a control. Results It is showed that integrin β 1 distributed scattering in cytomembrane and stained faintly, and F-actin located in cytoplasm without polarity and stained faintly also showed in the control. After pretreating EC with shear stress for different time ,we found that incresing time exposed to shear stress increased the staining of F-actin and integrin β 1. Integrin β 1 enchanced gradually with a maximum at 12h then decreased and tended to realign in the direction of F-actin. F-actin kept on increasing staining until 24h and tended to polymerize into strong stress fiber around the cell periphery and realign in the direction of flow. Conclusion The results suggested that integrin β 1 as an important adhesion molecular interaction with F-actin may play a key role in the mechanotransduction of co-cultured vascular endothelial cells .

Abstract:Objective To investigate the effect of different diameter powder on setting time and compressive stress of carbonated hydroxyapatite cement (CHC). Methods 400, 600 meshes and ultramicropowder were prepared by grind and ultramicropowder methods, and the effects on setting time and compressive stress were observed. Results The average diameter of ultramicropowder was 3.109μm, and the specific surface area was 2.288m 2/cm 3. Under 37℃ and 100% humidity, the setting time shorten along with the reduced diameter powder, and the compressive stress increased along with the reduced diameter powder. The initial setting time of ultramicropowder CHC was 3 minutes, and the final setting time was 8 minutes. The final compressive of ultramicropowder CHC stress was (51.042±3.728)MPa. Conclusion The results showed ultramicropowder CHC could solidify in situ with rational setting time and high compressive stress, which adapt to clinical application.

Abstract:Objective The purpose of this paper is to simulate the alterations of pressure-volume loop of left ventricle due to the changes of pre- and after-load and induced by cardiac valve diseases. Methods The simulations were performed by using Ursino model, which took into account the whole circulation system including heart, arterial and venous systems. The equations of flow across heart valves were modified in order to calculate the reverse flow in the condition of valves diseases. Results Firsly, the influences of pre-load, after-load of left ventricle and myocardial inotropism on ventricular pressure-volume loops were calculated. Based on these data, the pressure-volume loops with mitral obstruction, mitral inadequacy, aortic stenosis and both aortic stenosis and insufficiency were simulated. Conclusion The results showed that there are significant influences of heart valves disease on the left ventricle function. It also indicated that the clamped parameter model describing the whole cardiovascular system is an adequate tool to be applied to simulate not only vascular system, but also the heart function.

Abstract:Objective A circuit model of left coronary artery was created to analysis the theory of external counterpulstion (EECP) enhanced perfusion blood flow of ischemic myocardium. Methods From Newton's equation and the continuity equation, an equivalent analogue circuit model can be derived for each small segment of the coronary arteries. By replacing each segment with its analogue circuit model, a final model of left coronary artery can be constructed. Using Pspice simulation software, The model was simulated using experimentally measured aortic pressure. Results The model simulation shows that perfusion blood flow through left coronary artery were increased obviously with augmentations of perfusion pressure by EECP during diastolic period. Conclusion The results demonstrate that raising perfusion pressure with EECP can improve perfusion blood flow in left coronary artery.

Abstract:Objective To explore new method and its clinical significance, i.e. using the wavelets transform in combination with complex cepstrum to study neutrophil distribution by monitoring their cell membrane signals in blood. Methods "Virtual Box count" method was used to collect blood cell membrane signals, which was subsequently processed using the wavelets transform combined with the complex cepstrum analysis method. Results Based on data analysis, a new concept using "concentrated group"of blood cell membrane for studying states of blood cell distribution was established. This enabled to calculate the main maximum of wavelets transform in combination with the complex cepstrum, which served as an accurate parameter of the "concentrated group" interval of neutrophil distribution in the blood under the different circumstances.Conclusion This method is simply, can better reflect blood cell membrane microstructural characteristics of cell distribution state. It is a effective method to express the characteristics of the "concentrated group interval" in the blood cell membrane.

Abstract:Objective To provide clinical reference data on the stress-relaxation and creep- viscoelastic properties of renal arteries from fresh and healthy human cadavers. Method stress-relaxation and creep- viscoelastic tests were conducted for the renal arteries. Results The stress-relaxation and creep data were obtained. By regression analysis, the characteristics of the normalized stress-relaxation and the normalized creep behavior were established. Conclusion There was a big variation in the relaxation and creep behavior during the first 600 seconds of the testing. At 7200 seconds, the stress-relaxation and creep curve reached the equilibrium. At the time of 7200 seconds the measures of relaxation was 0.280 MPa and that of creep was 13.98%. These results suggested that the renal arteries belonged to solid biological materials characterized with viscoelastic properties.

Abstract:Objective To investigate the effects of pharyngeal respiratory pressure on the mechanical properties of soft palate in obstructive sleep apnea hypornea syndrome (OSAHS). Methods An animal model of OSAHS was developed from SD rats, and the elastic properties of the soft palate of the rat model were measured in vitro through uniaxial tensile experiments. Results To compare with the control one, the mechanical properties of the soft palate and the phenomenon of its remodeling related to OSAHS were discussed. Conclusion It was shown that pharyngeal respiratory pressure analogous to that of OSAHS episodes can cause the soft palate remodeling prone to OSAHS's formation and development.

Abstract:Objective To define the optimal internal fixation method by means of studying the strength of various internal fixations of simulated fractures on posterior acetabular wall. Methods Eighteen preserved cadaveric hip joints were divided into three groups randomly. The simulated big isolated posterior wall fracture models were created by osteotomy in the middle of the outer rim of posterior acetabulum and the greater sciatic notch. The models were fixed with one of the three different methods: two cortical screws (CS), reconstruction plate (RP) and reconstruction plate plus two cortical screws (CS+RP). Then tests were performed on each model with 90°flexion of the hip. Measure the displacements of the fragments and the loadings when the displacements were 3mm. Results The displacements of fragments increased as the loading increased. There have high significant difference between the CS and RP or RP+CS (P<0.01), but no significance between the RP and CS+RP (P>0.05). Conclusion The ideal method of internal fixation of posterior acetabular wall fracture is RP. The strength of CS cannot maintain the stability of the fragment while RP+CS is not stronger than RP only and it may add more operative trauma and difficulty to operation.

Abstract:Objective This study examined the healing of acute articular cartilage injuries under the influence of meniscectomy.Methods New Zealand white rabbits were used for experiment. Cylindrical articualr cartilage defect with exposure of subcondral bone was surgically generated on the bilateral medial femoral condyli. The meniscus of the right knee was removed while the left knee was used as contralateral control by preserving its meniscus. The healing of articular cartilage (AC) defects was evaluated gross morphologically and histologically using both light microscopy and transmission electron microscopy (TEM). Results Gross morphologically, the surface of articular cartilage defects in the contralateral control knee looked normal in structure apart from its pale appearance at 10 weeks; while the right knees showed irregular surface and some clefts and loss of AC surface layer histologically, articular-like cartilage was formed in the repaired defect, which might be regenerated by condrocytes proliferation originated from subcondrol bone in the contralateral control knee at 10 weeks. In contrast, there was degenerative sign of the repaired articular-like cartilage in the right knees, which was characterized with surface clefts (fibrilillation) and detachment of surface AC. TEM showed many apoptotic chondrocytes in the experiment group, while there was normal cellular structure found in the contralateral controlat 10 weeks. Conclusion Meniscectomy was able to induce apoptosis of condrocytes, surface clefts and detachment of the repaired articular cartilage defect. Meniscus is a very important anatomical structure, which execute relevant biological function, i.e. by providing mechanical stability to the knee joint to ensure repair of the acute articular cartilage injury.

Abstract:Objective To investigate the probabilities of clinical application of Pyrford technique.Biomechanical testing was performed to evaluate biomechanical characteristics of patella fractures which fixed with the combination of cerclage wiring and a tension band(Pyrford technique). Methods Using ox cadaveric knee joints, transverse osteotomies of the patella were performed, and the simulated fractures fixed with the following techniques: the combination of cerclage wiring and a tension band(Pyrford technique), tension band with kirschner pins, and cerclage with wires alone. The effectiveness of fixation was measured and compared. Results Pyrford technique, same to tension band with kirschner pins, was fit for the biomechanical characteristics of patella. Pyrford technique could meet the need of strength, rigidity and physiological function of the knee joint. Conclusion The patella fractures fixed with the combination of cerclage wiring and a tension band(Pyrford technique) had advantages such as excellent biomechanical capabilities, anatomical reduction, simple operation, firm fixation, and suitable to function exercise in early stage.

Abstract:Objective To evaluate the effect of hip joint replacement. Methods Based on three famous assess standards of hip joint replacement, and web technology, the computer can collect and analysis the data of the patient. Results The results show that this system succeeds in estimating the effect of the false hip joint replacement. Conclusion Use the estimate system based on Internet , it can improve the quality and the speed of the estimation of post-operation of hip joint replacement. The estimating result can be used conveniently in the communications of doctors.

Abstract:Objective To study the biomechanics of allograft bone tissue, and to provide a suitable preservation method for bone allograft. Methods The femora of fresh corpse were gradient frozen (-2℃/min) to -60℃ after the pretreatment. And then put them into the cryopreservation refrigerator of -80℃. One month later, the biomechanical tests were carried on. Results The results of the biomechanical test were close to the data of fresh bone in former research. Conclusion The biomechanical characteristics of gradient freezing and cryopreservation bone allograft were close to the fresh bone. The method of this preservation could provide gist to the intending further research.

Abstract:作者在文中先给出了计算机辅助手术导航系统的工作原理及分类 ,并对其主要研究内容及关键技术进行了较全面的论述 ,分析了基于CT的导航系统、基于X线荧光透视的导航系统以及开放式的导航系统的功能特点 ,并指出了各类关键技术的临床适用范围。实验及临床证明计算机辅助导航系统在提高外科手术准确性等方面起到了很好的作用

Abstract:降解以及在降解过程中伴随的力学性能的变化是骨组织工程支架材料至为重要的两个特性。随着材料科学的快速发展 ,目前已有数目繁多的骨组织工程支架材料问世。作者综述了各类可降解骨组织工程支架材料的降解方式、降解时间、降解特点以及在降解过程中材料本身的力学性能的变化 ,并对可降解骨组织工程纳米支架材料的前景进行了展望

Abstract:作者介绍了细胞力学领域中细胞分裂、细胞增殖方面的研究进展。着重介绍了基底加载各种参数对细胞增殖的影响 ,机械拉伸对细胞粘附及生长的影响 ,力学环境对血管内皮细胞分裂过程的影响