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Objective To evaluate the effects of locked plates with different screw layouts on stability of the internal fixation system for femoral shaft fracture, so as to provide guidance for clinical study on screw layout of the internal fixation system for femoral shaft fracture. Methods Orthogonal test design method was used with 4 groups of screws at 3 parametric levels. Biomechanical properties of the internal fixation system for femoral shaft fracture under 9 screw layouts were analyzed respectively by the finite element method, and 4 inspection indices, namely, the maximum equivalent stress of the plate, the screw and the femur, and the maximum axial displacement of the internal fixation system were obtained from each group of the experiment, and the orthogonal test weight matrix analysis method was conducted for data analysis. Results The influences of different screw parameters on stability of the internal fixation system varied, and the maximum weights of the 4 sets of screw parameters in stability of the internal fixation system were 13.86%, 7.57%, 7.53% and 5.91%, respectively. Conclusions The best scheme for screw layout in orthogonal test is the screw with none-fixed threaded holes in the first group, the single cortical screws with fixed threaded holes in the second group and the double cortical screws with fixed threaded holes in the third and fourth group.
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Objective To explore the effects of screw configurations on bone healing, so as to provide the basis for related fracture treatment. Methods The process of bone healing under different screw configurations was studied by finite element method, and the change in the process of callus growth during healing periods was simulated by interfragmentary strain theory (IFS). The iterative process for renewing callus modulus in every finite element was conducted by the second-developed ABAQUS based on Python scripting language, thus the process of fracture healing was simulated. Results The effect from different numbers of screws on bone healing was smaller than that from different working length of bone plates. On the premise of stable fixation, given the certain working length of bone plates, the effect from different screw numbers on stress distributions in plates or screws was relatively small, while the effect from different working length on stress distributions in plates or screws was relatively large, and the stress distribution in plates was larger than that in screws at different working length. Conclusions It is necessary to take more consideration on working length of bone plates than the number of screws when they are under a stable fixed situation, and it is a wise choice to reduce the screw numbers and choose a suitable working length for bone healing process.
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BACKGROUND:Conventional ophthalmic delivery of ciliary neurotrophic factor (CNTF) is extremely difficult to pass the blood-retinal barrier, resulting in a very low bioavailability and the need of long-term drug delivery. To solve the problem, the CNTF can be encapsulated in a semi-permeable membrane to form a microcapsule, which may then achieve the release of bioactive substances encapsulated, or bioactive molecules secreted by living cels and smal molecular metabolites through semi-permeability of the special membrane. OBJECTIVE:To prepare a special structural CNTF sustained-release microcapsule. METHODS: A selected poly(ether sulfone) holow fiber was cut into 1 cm long with its two ends sealed by 1181-M medical adhesive using UV curing. To prepare CNTF encapsulated microcapsule, one end was first sealed, and then the CNTF was loaded to poly(ether sulfone) microcapsule from the other end which then was sealed. The leaching liquor of sustained-release microcapsule was co-cultured with mouse fibroblast L929, to observe the cytotoxicity of the microcapsule. The sustained-release microcapsule was co-cultured with mouse retinal pigment epithelial cels, to observe the celladhesion ability of the microcapsule. The CNTF sustained-release microcapsule was immersed in physiological saline, to observe the degradability. Moreover,in vitro release behavior of immunoglobulin and CNTF were evaluated. RESULTS AND CONCLSION:The CNTF sustained-release microcapsule had an inner diameter of about 398 μm and a membrane thickness of about 145 μm. The microcapsule presents a lot of macropores in the outer wal and many 10 nanometers micropores in the inner wal. The sustained-release microcapsule was not degraded in saline within 4 months, indicating good cellcompatibility. The microcapsule can selectively release CNTF while protecting against invading of antibodies (IgG), showing its good selective permeability. Meanwhile, the sustained-release microcapsule improved the initial burst release of traditional drug delivery vesicles. The microcapsule presents a mild sudden release in the middle stage, and then a sustained release.
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ObjectiveTo screen the items of Advanced Cancer patient Needs Questionnaire (ACNQ)and develop a short version.MethodsA total of 80 cancer patients of middle and advanced stage were recruited.The items were screened with variation degree method and factor analysis method,combined with clinical meaning of the items.The reliability and validity of newly-development scale were confirmed with new sample of 60 cancer patients.ResnltsThrough statistical methods 12 items were removed from the original scale,forming a short version of Advanced Cancer patient Needs Questionnaire:ACNQ-29.The correlation coefficient of split half reliability was 0.913.The Cronbach′s α coefficient of all items was 0.923.Through principal components and factor analysis,7 principal components were gained including basically the 4 dimensions of physiological,psychological,spiritual and social domain with accumulation contribution of 75.478％.ConclusionsNew scale has good reliability and validity,and more easily for patients to complete.It has feasibility and practicability.
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Objective To compare the efficiency of χ~2-Fisher's exact test which is one of the competitive null hypothesis approaches with SAM-GS which belongs toself-contained null hypothesis approaches. Methods The two methods were used to analyze a simulation experiment which contained five different scenarios. The results were compared with the simulated initialization,and assessing indexes were calculated to compare the efficiency. Results Under the same conditions,SAM-GS always have higher power than that of χ~2-fisher's exact test. However, the final inference is equivalent, namely if the difference between the two groups are smaller than 0.30,the two methods can not be better to identify differences between them. By contrary, when the differences between the two phenotypes are larger than 0.30, the two ways can both identify differences. Conclusion SAM-GS tends to have slightly higher power thanχ~2-Fisher' s exact test. The two methods can be used for screening enrichment gene sets of gene expression profile.χ~2-Fisher's exact test has the important advantage of being able to analyze multi-class phenotype.
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A stochastic model of intracellular calcium oscillations is put forward by taking into account the random opening-closing of Ca2+ channels in endoplasmic reticulum (ER) membrane. The numerical results of the stochastic model show simple and complex calcium oscillations, which accord with the experiment results.
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Humanos , Canais de Cálcio , Metabolismo , Sinalização do Cálcio , Retículo Endoplasmático , Metabolismo , Espaço Intracelular , Cinética , Matemática , Modelos Biológicos , Processos EstocásticosRESUMO
A stochastic model of intracellular calcium oscillations is put forward by taking into account the random opening-closing of Ca2+ channels in endoplasmic reticulum (ER) membrane. The numerical results of the stochastic model show simple and complex calcium oscillations, which accord with the experiment results.