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Objective To evaluate biomechanical properties of the personalized titanium alloy short femoral prosthesis by finite element analysis. Methods Based on the validated femoral finite element model, the base of the femoral neck was simulated, and by inserting different short femoral prostheses, four total hip replacement (THR) models, namely, the SMF stem model (Model A), BE1 stem model (Model B), MINI stem model (Model C) and personalized stem model (Model D) were established, respectively. The same loads and constraints were applied to four groups of models, and the von Mises stress distribution and deformation were calculated and analyzed, so as to compare mechanical stability of each model. Results The deformation of all THR models was smaller than that of the femur model under physiological state. The deformation of Model B was close to that of Model C, and the deformation of Model A was close to that of Model D. The peak stress of Model C was higher than that of the other 3 models, reaching 9555 MPa. The overall stress trend was Model C > Model B > Model D> Model A > Model under physiological state. Conclusions The peak stress, stress distribution of personalized short femoral stem were similar to that of SMF stem, with reasonable stress distribution, small stress shielding of the proximal femur, minimum overall deformation and shear stress of the prosthesis, and its effectiveness and stability could meet the requirements of human biomechanics, which could provide references for joint surgeons and prosthesis researchers.
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Objective To observe the changes and significance of the protein expression levels of nuclear factor-κB p65 (NF-κB p65), transforming long factor-β1 (TGF-β1) and apoptosis-related factors Bcl-2 and Bax in myocardial tissue of Bama miniature pig model of diabetic cardiomyopathy (DCM). Methods Ten healthy male Guangxi Bama miniature pigs, aged 4 to 5 months old, were selected and divided into control group and model group according to the random number table method, with 5 pigs in each group. After 12 hours of fasting in the two groups, the DCM model was replicated by intravenous injection of streptozotocin (STZ) 150 mg/kg; for the Bama miniature pigs in the control group, citric acid-sodium citrate buffer 150 mg/kg was injected intravenously. After 10 months of modeling, the basic conditions of the two groups of animals were observed and their fasting blood glucose (FPG) levels were detected. The protein expression levels of NF-κB p65, TGF-β1, Bcl-2 and Bax in myocardial tissue of two groups were detected by Western Blot and the pathological changes of myocardial tissue were observed under electron microscope. Results In the model group, 4 models were successfully established, and 1 died. The model pigs had symptoms such as polydipsia, polyphagia, polyuria and decreased body weight. The FPG level in the model group was significantly higher than that in the control group (mmol/L: 25.53±3.75 vs. 4.68±0.77, P < 0.01). Compared with the control group, the protein expression levels of NF-κB p65, Bax and TGF-β1 in the myocardial tissue of model group were significantly increased (NF-κB p65/GAPDH: 0.46±0.05 vs. 0.38±0.02, Bax/GAPDH: 0.46±0.01 vs. 0.35±0.01, TGF-β1/GAPDH: 0.39±0.01 vs. 0.33±0.01, all P < 0.05) and the expression level of Bcl-2 protein was significantly decreased (Bcl-2/GAPDH: 0.33±0.01 vs. 0.42±0.01, P < 0.01). Electron microscopy results showed that the myofibrils of myocardial tissue in the DCM model group were disordered, and the number of mitochondria in the gap was significantly reduced. A large number of mitochondria with vacuolar degeneration were observed. Conclusions The DCM model of Bama miniature pigs can be successfully replicated after 10 months of high-dose STZ disposable ear vein injection. The DCM model miniature pigs have obvious glucose metabolism disorder, and their myocardial tissue has inflammatory reaction, cardiomyocyte apoptosis and fibrosis.
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Objective: To establish an electrochemical method for the determination of phenol. Methods: An electrochemical workstation with three electrodes system was used with glassy carbon electrode as working electrode, Ag/AgCl as reference electrode and Pt as counter electrode. Cyclic voltammetry and differential pulse voltammetry were used for the determination of phenol. Results:Under the condition of 4% Na2SO4as the supporting electrolyte, phenol showed an obvious oxidation peak on the glassy carbon elec-trode. The peak current increased linearly with the concentration of phenol within the range of 0. 8 μg·ml-1-10. 2 μg·ml-1( r=0. 997 5). The lower limit of detection was 0. 20 μg·ml-1. The average recovery was 101. 2% (RSD=2. 2% , n=6). Conclusion:The method is simple and accurate, and can be used for the determination of phenol.
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BACKGROUND:Electron beam melting rapid prototyping technology, has the characteristic of shaping precisely and complexly, is a new type of rapid prototyping technology using metal powder. Now, it has shown unique advantages in the fields of aerospace, automotive and medical implant equipments. OBJECTIVE: To explore the properties of the product, the customization ability of orthopedic implants through electron beam melting rapid prototyping, especial y the ability of inducing bone ingrowth. METHODS:We retrieved PubMed Database, China Journal Ful-text Database, and China National Knowledge Infrastructure, as wel as Dongfang Daily, World Science, and Chinese Journal of Orthopaedics by hand, and assembly documents in Chinese and English. Retrieval time was up to September 2013. Inclusion criteria: ① articles concerning electron beam melting rapid prototyping technology; ② articles addressing surgical implants. A total of 50 articles were included. RESULTS AND CONCLUSION:Electron beam melting state Ti6Al4V orthopedic implant has a good comprehensive performance, since the three-dimensional porous structure via electron beam melting rapid prototyping, which has a characteristic of customization, can induce bone ingrowth.
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Objective To assess pathological features of muscles as well as microvascular changes between muscle fibers in patients with dermatomyositis (DM),and to analyze pathological differences in muscles between DM and polymyositis (PM).Methods Specimens were obtained from involved muscles of 16 patients with DM,5 patients with PM,and from normal muscles of 9 patients with bone trauma (controls).Routine histopathological examination and immunohistochemical staining for CD34 and CD61 were conducted.Results Of the 16 patients with DM,6 (37.5％) had perifascicular atrophy,3 ( 18.8 ％) had an obvious inflammatory cell infiltration around microvessels between muscle fibers.Perifascicular atrophy was absent in muscle specimens from patients with PM or bone trauma.The number of CD34-positive microvessels between muscle fibers was reduced in patients with DM,but normal in those with PM.CD61 was positive in perifascicular area of 10 patients (5 moderately positive and 5 weakly positive) with DM,with an expression rate of 62.5％,however,only 1 case of PM was weakly positive for CD61,and all the controls were negative.Conclusions There is a decrease in the number of microvessels but an enhancement of neovascularization between muscle fibers in involved muscles of patients with DM,which may serve as a pathological marker to distinguish DM from PM.
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OBJECTIVE: The success of joint prosthesis greatly depends on the materials, which should be a perfect combination of physics, chemistry, biomechanics and clinical sciences in choice of them. In addition, the effect of manufacture technology can not be neglected. So, it is significant to probe into the systematic basis in materials selection of joint prosthesis.DATA SOURCES: A computer-based search was conducted in Pubmed database for articles about joint prosthesis published before April 2006 with the key words of "artificial joint materials, biomaterial", and the language was limited to English. Meanwhile, Chinese Journal Full-text Database (CJFD) and Wanfang database were looked for relevant literatures published before April 2006 with the key words of "artificial joint material, biomedical material", and the language was limited to Chinese. Besides,the standards for materials were searched in Chinese service net for standard consultation with the key words of "implants for surgery" in both Chinese and English. At the same time, relevant books were also manually searched.STUDY SELECTION: Data were checked in the first trial, and related articles according to the criteria of research were looked for the full text.Inclusion criteria: ① Requirements for artificial joint material. ② Relevant standards for artificial joint of surgical implants. Exclusion criteria: Repetitive studies were excluded.DATA EXTRACTION: A total of 390 domestic and overseas articles,which were in relation to the mechanical properties of artificial joint material and bone and measurement of the overall dimensions of knee joint,were collected. There were still 242 relevant standards, while the repetitive studies and similar researches were excluded. Ten typical articles and 25 standards in collection were summed up and reviewed.DATA SYNTHESIS: ①Close combination of physics, chemistry, biomechanics and clinical sciences is sufficiently embodied in the selection of the materials. ② Two aspects must be taken into consideration: Requirements for function of the implant and the responses inside the human body.③ Main types of materials for joint prosthesis: biomedical metallic material, biomedical inorganic material of nonmetal, bioceramic, biomedical compound materials and so on. All kinds of materials that have been adopted should accord with the international or state or trade standards.④ The final determination of materials should meet the comprehensive requirements of standards, laws and regulations, as well as strategic targeting. CONCLUSION: Based on engineering, the fundamental principles of materials selection for joint prosthesis are illustrated from the following angles: clinical requirements for materials of replacement, attentions in joint prosthesis design, commonly used biomedicine materials performance, requirements of product registration and laws & regulations related to the materials, the strategy in the choice of material standard etc. As a result, a valuable system approach is provided for joint-prosthesis designers to select materials.