A comparative study of urinary levels of multiple metals and neurotransmitter correlations between GDM and T2DM populations.

OBJECTIVE: The pathogenesis of GDM and T2DM are closely related to various metals in vivo, and changes in the concentration of these metal exposures can lead to neuropathy through the DNA damage pathway caused by the accumulation of ROS. METHOD: Urine samples were analyzed for heavy metals and trace elements by ICP-MS, neurotransmitter metabolites by HPLC, 8-OH-dG by HPLC-MS and metabolomics by UPLC-MS. RESULT: Cd and Hg were risk factors for T2DM. There was a positive correlation between 8-OH-dG and neurotransmitter metabolites in both two populations. For GDM, the metabolite with the largest down-regulation effect was desloratadine and the largest up-regulation effect was D-glycine. That tyrosine and carbon metabolites were upregulated in the GDM population and downregulated in the T2DM population. CONCLUSION: The BMI, urinary Cd and Hg endo-exposure levels correlated with elevated blood glucose, and the latter may cause changes in the DNA damage marker 8-OH-dG in both study populations and trigger common responses to neurological alterations changes in the neurotransmitter. Tyrosine, carbonin metabolites, alanine, aspartate, and glutamate were signature metabolites that were altered in both study populations. These indicators and markers have clinical implications for monitoring and prevention of neurological injury in patients with GDM and T2DM.

Stability of Three-Dimensional Printed Custom-Made Metaphyseal Cone for Tibial Bone Defects Reconstruction: A Finite Element Analysis and Biomechanical Study.

OBJECTIVES: The reconstruction of bone defects in tibial revision knee arthroplasty is challenging. In this study, we evaluated the primary stability of a novel three-dimensional (3D)-printed custom-made metaphyseal cone for Anderson Orthopedic Research Institute (AORI) IIb or III bone defect reconstruction in tibial revision knee arthroplasty using the combination of finite-element analysis and biomechanical experiments. METHODS: In the finite-element analysis, AORI II b and III medial tibial bone defects were designed at varying depths. A novel 3D-printed custom-made metaphyseal cone was designed and used to reconstruct the bone defect with or without a stem in simulated revision total knee arthroplasty (RTKA). A no-stem group and a stem group were established (based on whether a stem was used or not). Von Mises stress and micromotion were calculated with varying depths of bone defects, ranging from 5 mm to 35 mm, and then micromotions at the bone-implant interface were calculated and compared with the critical value of 150 µm. In the biomechanical experiment, the no-stem group was used, and the same bone defects were made in four synthetic tibias using patient-specific instruments. Micromotions at the bone-implant interface were investigated using a non-contact optical digital image correlation system and compared with the critical value of 150 µm. RESULTS: When the bone defect was <30 mm, micromotions at the bone-implant interface in the finite-element analysis were all below 150 µm both in the stem groups and no-stem groups, whereas those in the biomechanical experiment were also below 150 µm in the no-stem group. CONCLUSIONS: The 3D-printed custom-made metaphyseal cone in RTKA has excellent primary stability and does not require stems in reconstructing tibial AORI type IIb or III bone defects with a depth of <30 mm.

The effect of pore size on the mechanical properties, biodegradation and osteogenic effects of additively manufactured magnesium scaffolds after high temperature oxidation: An in vitro and in vivo study.

The effects of pore size in additively manufactured biodegradable porous magnesium on the mechanical properties and biodegradation of the scaffolds as well as new bone formation have rarely been reported. In this work, we found that high temperature oxidation improves the corrosion resistance of magnesium scaffold. And the effects of pore size on the mechanical characteristics and biodegradation of scaffolds, as well as new bone formation, were investigated using magnesium scaffolds with three different pore sizes, namely, 500, 800, and 1400 µm (P500, P800, and P1400). We discovered that the mechanical characteristics of the P500 group were much better than those of the other two groups. In vitro and in vivo investigations showed that WE43 magnesium alloy scaffolds supported the survival of mesenchymal stem cells and did not cause any local toxicity. Due to their larger specific surface area, the scaffolds in the P500 group released more magnesium ions within reasonable range and improved the osteogenic differentiation of bone mesenchymal stem cells compared with the other two scaffolds. In a rabbit femoral condyle defect model, the P500 group demonstrated unique performance in promoting new bone formation, indicating its great potential for use in bone defect regeneration therapy.

A pH-neutral bioactive glass coated 3D-printed porous Ti6Al4V scaffold with enhanced osseointegration.

Osseointegration is vital for the success of non-degradable implants like those made of titanium alloys. In order to promote osseointegration, implants are made porous, providing space for bone ingrowth. Despite extensive optimization of the pore geometry and porosity, bone ingrowth into implants is still marginal; further modification to promote bone ingrowth as well as osseointegration becomes paramount. In this study, a pH neutral bioactive glass with the composition of 10.8% P2O5-54.2% SiO2-35% CaO (mol%; hereinafter referred to as PSC) was successfully coated on 3D-printed porous Ti6Al4V scaffolds using an in situ sol-gel method. This PSC coating is strongly bonded to the substrate and quickly induces the formation of hydroxyapatite on the scaffold surface upon contact with body fluid. In vitro, the PSC-coated Ti6Al4V scaffolds showed superior biocompatibility, cell proliferation promotion, cell adhesion, osteogenic differentiation and mineralization compared to their bare counterparts, implying better osseointegration. In vivo experiments confirmed this expectation; after being implanted, the coated scaffolds had more bone ingrowth and osseointegration, and consequently, higher push-out strength was achieved, proving the validity of the proposed concept in this study. In conclusion, PSC coating on 3D-printed porous Ti6Al4V scaffolds can improve osteogenesis, bone ingrowth, and osseointegration. Together with the versatility of this in situ sol-gel coating method, titanium alloy implants with better biological performances may be developed for immediate clinical applications.

[Rapid femur modeling method based on statistical shape model].

The geometric bone model of patients is an important basis for individualized biomechanical modeling and analysis, formulation of surgical planning, design of surgical guide plate, and customization of artificial joint. In this study, a rapid three-dimensional (3D) reconstruction method based on statistical shape model was proposed for femur. Combined with the patient plain X-ray film data, rapid 3D modeling of individualized patient femur geometry was realized. The average error of 3D reconstruction was 1.597-1.842 mm, and the root mean square error was 1.453-2.341 mm. The average errors of femoral head diameter, cervical shaft angle, offset distance and anteversion angle of the reconstructed model were 0.597 mm, 1.163°, 1.389 mm and 1.354°, respectively. Compared with traditional modeling methods, the new method could achieve rapid 3D reconstruction of femur more accurately in a shorter time. This paper provides a new technology for rapid 3D modeling of bone geometry, which is helpful to promote rapid biomechanical analysis for patients, and provides a new idea for the selection of orthopedic implants and the rapid research and development of customized implants.

Kinetochore-associated protein 1 promotes the invasion and tumorigenicity of cervical cancer cells via matrix metalloproteinase-2 and matrix metalloproteinase-9.

Cervical cancer, a common cancer in women, has become a serious social burden. Kinetochore-associated protein 1 (KNTC1) that regulates the cell cycle by regulating mitosis is related to the malignant behavior of different types of tumors. However, its role in the development of cervical cancer remains unclear. In this study, we initially explored the role of KNTC1 in cervical cancer. KNTC1 expression and relevant information were downloaded from The Cancer Genome Atlas (TCGA) and dataset GSE63514 in the Gene Expression Omnibus (GEO) database for bioinformatics analyses. Cell proliferation was detected by cell counting kit-8 (CCK8) and colony formation assays. Wound healing and Transwell assays were used to evaluate cell migration and invasion abilities. Protein expression levels of matrix metallopeptidase 2 (MMP2) and matrix metallopeptidase 9 (MMP9) were measured by western blotting. Nude mouse models of subcutaneous xenograft tumor were constructed to analyze tumor growth in vivo. CCK8 and colony formation assay results demonstrated that the proliferation rate of SiHa and C-33A cells decreased when KNTC1 was silenced. Western blot and Transwell assays indicated that KNTC1 knockdown weakened the invasion and migration abilities of SiHa and C-33A cells and decreased the expression of MMP-2 and MMP-9. In-vivo experiments suggested that the inhibition of KNTC1 reduced tumor growth. Taken together, our study showed that KNTC1 plays an important role in cervical cancer. Further, we verified the promotional effect of KNTC1 on cervical cancer through in-vivo and in-vitro experiments and speculated that KNTC1 might mediate tumor invasion via MMP9 and MMP2.

Biodegradable magnesium alloy WE43 porous scaffolds fabricated by laser powder bed fusion for orthopedic applications: Process optimization, in vitro and in vivo investigation.

Laser powder bed fusion (L-PBF) of magnesium (Mg) alloy porous scaffolds is expected to solve the dual challenges from customized structures and biodegradable functions required for repairing bone defects. However, one of the key technical difficulties lies in the poor L-PBF process performance of Mg, contributed by the high susceptibility to oxidation, vaporization, thermal expansion, and powder attachment etc. This work investigated the influence of L-PBF energy input and scanning strategy on the formation quality of porous scaffolds by using WE43 powder, and characterized the microstructure, mechanical properties, biocompatibility, biodegradation and osteogenic effect of the as-built WE43 porous scaffolds. With the customized energy input and scanning strategy, the relative density of struts reached over 99.5%, and the geometrical error between the designed and the fabricated porosity declined to below 10%. Massive secondary phases including intermetallic precipitates and oxides were observed. The compressive strength (4.37-23.49 MPa) and elastic modulus (154.40-873.02 MPa) were comparable to those of cancellous bone. Good biocompatibility was observed by in vitro cell viability and in vivo implantation. The biodegradation of as-built porous scaffolds promoted the osteogenic effect, but the structural integrity devastated after 12 h by the immersion tests in Hank's solution and after 4 weeks by the implantation in rabbits' femur, indicating an excessively rapid degradation rate.

Correlation between Preoperative Serum Albumin-Globulin Ratio and Prognosis of Patients Undergoing Low Rectal Cancer Surgery.

BACKGROUND: To explore the correlation between preoperative serum albumin-globulin ratio (AGR) and the prognosis of patients undergoing low rectal cancer surgery. METHODS: A total of 152 patients treated from June 2013 to June 2015 were selected. They were divided into survival group (n = 128) and death group (n = 24). Their general clinical data and preoperative and postoperative serum albumin (ALB), globulin (GLB) levels, and AGR were compared. Multivariate logistic regression analysis was performed for influencing factors for postoperative death. A nomogram prediction model was established based on independent risk factors. The predictive value of AGR for clinical outcomes was analyzed by receiver operating characteristic (ROC) curve, and the optimal cut-off value was obtained. The correlation between AGR and postoperative clinical outcomes was analyzed. The patients were divided into group A and B according to cut-off value, survival curves were plotted by Kaplan-Meier method, and 5-year survival rates were compared. RESULTS: There were significant differences in tumor stage, cell differentiation, depth of tumor invasion, lymph node metastasis, chemotherapy, preoperative ALB, GLB, and AGR between the two groups, which were all independent risk factors for death. After operation, ALB and AGR significantly declined and were significantly lower in the death group than those in the survival group. The death group had significantly higher GLB level than that of the survival group. The optimal cut-off value of AGR for predicting death was 1.73. AGR was significantly correlated with postoperative clinical outcomes. The survival rate of patients with AGR > 1.73 significantly exceeded that of cases with AGR ≤ 1.73. CONCLUSIONS: The preoperative serum AGR is an independent risk factor for the postoperative clinical outcomes of patients with low rectal cancer and has a high predictive value. Lower AGR indicates higher risk of postoperative death.

Surface treatment of 3D printed porous Ti6Al4V implants by ultraviolet photofunctionalization for improved osseointegration.

Three-dimensional (3D)-printed porous Ti6Al4V implants play an important role in the reconstruction of bone defects. However, its osseointegration capacity needs to be further improved, and related methods are inadequate, especially lacking customized surface treatment technology. Consequently, we aimed to design an omnidirectional radiator based on ultraviolet (UV) photofunctionalization for the surface treatment of 3D-printed porous Ti6Al4V implants, and studied its osseointegration promotion effects in vitro and in vivo, while elucidating related mechanisms. Following UV treatment, the porous Ti6Al4V scaffolds exhibited significantly improved hydrophilicity, cytocompatibility, and alkaline phosphatase activity, while preserving their original mechanical properties. The increased osteointegration strength was further proven using a rabbit condyle defect model in vivo, in which UV treatment exhibited a high efficiency in the osteointegration enhancement of porous Ti6Al4V scaffolds by increasing bone ingrowth (BI), the bone-implant contact ratio (BICR), and the mineralized/osteoid bone ratio. The advantages of UV treatment for 3D-printed porous Ti6Al4V implants using the omnidirectional radiator in the study were as follows: 1) it can significantly improve the osseointegration capacity of porous titanium implants despite the blocking out of UV rays by the porous structure; 2) it can evenly treat the surface of porous implants while preserving their original topography or other morphological features; and 3) it is an easy-to-operate low-cost process, making it worthy of wide clinical application.

A simple prediction model of hyperuricemia for use in a rural setting.

Currently, the most widely used screening methods for hyperuricemia (HUA) involves invasive laboratory tests, which are lacking in many rural hospitals in China. This study explored the use of non-invasive physical examinations to construct a simple prediction model for HUA, in order to reduce the economic burden and invasive operations such as blood sampling, and provide some help for the health management of people in poor areas with backward medical resources. Data of 9252 adults from April to June 2017 in the Affiliated Hospital of Guilin Medical College were collected and divided randomly into a training set (n = 6364) and a validation set (n = 2888) at a ratio of 7:3. In the training set, non-invasive physical examination indicators of age, gender, body mass index (BMI) and prevalence of hypertension were included for logistic regression analysis, and a nomogram model was established. The classification and regression tree (CART) algorithm of the decision tree model was used to build a classification tree model. Receiver operating characteristic (ROC) curve, calibration curve and decision curve analyses (DCA) were used to test the distinction, accuracy and clinical applicability of the two models. The results showed age, gender, BMI and prevalence of hypertension were all related to the occurrence of HUA. The area under the ROC curve (AUC) of the nomogram model was 0.806 and 0.791 in training set and validation set, respectively. The AUC of the classification tree model was 0.802 and 0.794 in the two sets, respectively, but were not statistically different. The calibration curves and DCAs of the two models performed well on accuracy and clinical practicality, which suggested these models may be suitable to predict HUA for rural setting.

Three-dimensional-printed individualized porous implants: A new "implant-bone" interface fusion concept for large bone defect treatment.

Bone defect repairs are based on bone graft fusion or replacement. Current large bone defect treatments are inadequate and lack of reliable technology. Therefore, we aimed to investigate a simple technique using three-dimensional (3D)-printed individualized porous implants without any bone grafts, osteoinductive agents, or surface biofunctionalization to treat large bone defects, and systematically study its long-term therapeutic effects and osseointegration characteristics. Twenty-six patients with large bone defects caused by tumor, infection, or trauma received treatment with individualized porous implants; among them, three typical cases underwent a detailed study. Additionally, a large segmental femur defect sheep model was used to study the osseointegration characteristics. Immediate and long-term biomechanical stability was achieved, and the animal study revealed that the bone grew into the pores with gradual remodeling, resulting in a long-term mechanically stable implant-bone complex. Advantages of 3D-printed microporous implants for the repair of bone defects included 1) that the stabilization devices were immediately designed and constructed to achieve early postoperative mobility, and 2) that osseointegration between the host bone and implants was achieved without bone grafting. Our osseointegration method, in which the "implant-bone" interface fusion concept was used instead of "bone-bone" fusion, subverts the traditional idea of osseointegration.

A Nomogram Model that Predicts the Risk of Diabetic Nephropathy in Type 2 Diabetes Mellitus Patients: A Retrospective Study.

OBJECTIVE: To construct a novel nomogram model that predicts the risk of diabetic nephropathy (DN) incidence in Chinese patients with type 2 diabetes mellitus (T2DM). METHODS: Questionnaire surveys, physical examinations, routine blood tests, and biochemical index evaluations were conducted on 1095 patients with T2DM from Guilin. A least absolute contraction selection operator (LASSO) regression and multivariable logistic regression analysis were used to screen out DN risk factors. A logistic regression analysis incorporating the screened risk factors was used to establish a predictive nomogram model. The performance of the nomogram model was evaluated using the C-index, an area under the receiver operating characteristic curve (AUC), calibration plots, and a decision curve analysis. Bootstrapping was applied for internal validation. RESULTS: Independent predictors for DN incidence risk included gender, age, hypertension, medicine use, duration of diabetes, body mass index, blood urea nitrogen level, serum creatinine level, neutrophil to lymphocyte ratio, and red blood cell distribution width. The nomogram model exhibited moderate prediction ability with a C-index of 0.819 (95% confidence interval (CI): 0.783-0.853) and an AUC of 0.813 (95%CI: 0.778-0.848). The C-index from internal validation reached 0.796 (95%CI: 0.763-0.829). The decision curve analysis displayed that the DN risk nomogram was clinically applicable when the risk threshold was between 1 and 83%. CONCLUSION: Our novel and simple nomogram containing 10 factors may be useful in predicting DN incidence risk in T2DM patients.

Decrease in leptin mediates rat bone metabolism impairments during high-fat diet-induced catch-up growth by modulating the OPG/RANKL balance.

Due to catch-up growth (CUG), there are adverse effects on human health. However, there is little information about its influence on bone metabolism. This study aimed to investigate the effects of leptin on bone metabolism and formation during high-fat diet (HFD)-induced CUG. We randomly divided male Wistar rats (5 weeks old) into four groups: control (CTL), caloric restriction and normal chow (RN), caloric restriction (4 weeks), and HFD (RH), and RH + leptin antagonist (RH + LEPA). We monitored body weights, biochemical markers, and epididymal and perirenal fat in these rats. We then performed Hematoxylin and Eosin (H&E) staining to evaluate bone metabolism. We detected osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa b ligand (RANKL) by qRT-PCR and immunohistochemistry (IHC). We found that HFD increased the body weights in rats. In RN, RH, and RH + LEPA groups, major biochemical markers of bone metabolism in rat serum were significantly altered. We found that epididymal and perirenal fat tissues of RH and RH + LEPA groups were higher than those in the RN group. Severe bone formation impairment in the distal diaphysis and metaphysis of the left femora and lumbar vertebra was seen in the RH group compared to RN, which was even aggravated by a leptin antagonist. OPG in the left femora and lumbar vertebra was lower in RH than the RN group. The leptin antagonist decreased OPG during CUG in the RH group, whereas RANKL expression showed an opposite alteration. During HFD-induced CUG, bone formation was mediated by OPG and RANKL and was affected by the leptin content.

Serum Amyloid A: A Potential Biomarker Assessing Disease Activity in Systemic Lupus Erythematosus.

BACKGROUND This study aimed to investigate the association between levels of serum amyloid A (SAA) and the activity of systemic lupus erythematosus (SLE). MATERIAL AND METHODS The study included 135 patients with SLE, including 52 patients with active SLE and 83 patients with inactive SLE and 149 healthy controls. The degree of activity of SLE was assessed using the SLE Disease Activity Index 2000 (SLEDAI-2K). Serum SAA levels were measured using a Cobas 8000 c702 modular analyzer. RESULTS The levels of SAA were significantly increased in patients with active SLE compared with patients with inactive SLE (median IQR, 16.65 mg/L; range, 9.35-39.68 mg/L, and median IQR, 2.30 mg/L, range, 1.30-4.80 mg/L) (p<0.001). Levels of SAA were significantly correlated with the SLEDAI-2K scores, the erythrocyte sedimentation rate (ESR), and hypersensitive C-reactive protein (Hs-CRP) in patients with SLE (r=0.726, p<0.001; r=0.631, p<0.001; r=0.774, p<0.001, respectively). Multivariate logistic regression analysis showed that the SAA values were independently associated with active SLE when controlled for white blood cell (WBC) count, red blood cell distribution width (RDW), ESR, and Hs-CRP (OR=1.772; p=0.01; 95% CI, 1.101-2.851). Receiver operating characteristic (ROC) curve analysis for SAA was used to identify patients with active SLE with an area under the curve of 0.971, a sensitivity of 90.4%, and a specificity of 94.0%. CONCLUSIONS SAA levels were significantly correlated with disease activity in patients with SLE.

Biomechanics study of a 3D printed sacroiliac joint fixed modular hemipelvic endoprosthesis.

BACKGROUND: Reconstructing pelvic type II + III defect caused by bone tumors is challenging. The purpose of this study was to explore the in vitro biomechanical properties of a reconstructed pelvis after periacetabular resection using three-dimensional (3D) printed sacroiliac joint (SIJ) fixed modular hemipelvic endoprosthesis. METHODS: Type II/II + III pelvic resection was simulated on an artificial pelvic model. The bilateral acetabulum and pubis were constrained, and the pelvis was maintained in a human physiological standing position. A vertically continuous linear load was applied on the upper face of S1 until obvious unloading or fixed failure occurred. A noncontact optical 3D strain measuring system was used to measure the strains and displacements at the selected area. FINDINGS: The strain at the points of interest did not obviously differ between the intact and reconstructed pelvis models. The difference in the displacement on the reconstructed side was 0.237 mm, and that on the contralateral side was 0.245 mm. The maximum differences in the displacement at the acetabulum were 0.209 mm (vertical) and 0.324 mm (horizontal). A crack at the superior rim of the contralateral acetabulum occurred, and failure loading of 7.126 kN. INTERPRETATION: The prosthesis in this study showed satisfactory mechanical properties and structural stability. According to the mechanical evaluations, the 3D printed sacroiliac-stabilized hemipelvic endoprosthesis can be used to reconstruct a stable acetabular structure, and there was little influence on the mechanical properties of the surrounding bone structures. The prosthesis design is reasonable, and the mechanical distribution on the reconstructed side was similar to that on the contralateral side.

Additively Manufactured Macroporous Titanium with Silver-Releasing Micro-/Nanoporous Surface for Multipurpose Infection Control and Bone Repair - A Proof of Concept.

Restoring large-scale bone defects, where osteogenesis is slow while infections lurk, with biomaterials represents a formidable challenge in orthopedic clinics. Here, we propose a scaffold-based multipurpose anti-infection and bone repairing strategy to meet such restorative needs. To do this, personalized multifunctional titanium meshes were produced through an advanced additive manufacturing process and dual "TiO2-poly(dopamine)/Ag (nano)" post modifications, yielding macroporous constructs with micro-/nanoporous walls and nanosilver bullets immobilized/embedded therein. Ultrahigh loading capacity and durable release of Ag+ were accomplished. The scaffolds were active against planktonic/adherent bacteria (Gram-negative and positive) for up to 12 weeks. Additionally, they not only defended themselves from biofilm colonization but also helped destroy existing biofilms, especially in combination with antibiotics. Further, the osteoblasts/bacteria coculture study displayed that the engineered surfaces aided MG-63 cells to combat bacterial invasion. Meanwhile, the scaffolds elicited generally acceptable biocompatibility (cell adhesion, proliferation, and viability) and hastened osteoblast differentiation and maturation (alkaline phosphatase production, matrix secretion, and calcification), by synergy of micro-/nanoscale topological cues and bioactive catecholamine chemistry. Although done ex vivo, these studies reveal that our three-in-one strategy (infection prophylaxis, infection fighting, and bone repair) has great potential to simultaneously prevent/combat infections and bridge defected bone. This work provides new thoughts to the use of enabling technologies to design biomaterials that resolve unmet clinical needs.

[Crosslinking modification of ultra high molecular weight polyethylene during joint arthroplasty].

OBJECTIVE: To explore the optimal condition of crosslinking modification of ultra high molecular weight polyethylene (UHMWPE) by gamma ray irradiation. METHODS: The hip and knee joint samples of UHMWPE were tested with regards to friction and wear performance at different doses of (60)Co radiation and heat treatment. And the optimal condition of crosslinking was determined by wear performance and physicochemical properties. RESULTS: Under the condition of 75 kGy irradiation and 150 °C heat treatment, crosslinked UHMWPE showed the best performance. Acetabular sample wear rate decreased 63.24% and knee sample wear rate decreased 59.95% compared with conventional UHMWPE. The modified material had excellent mechanical properties of impact strength 83 kJ/m², tensile strength 50.32 MPa, yield strength 21.83 MPa and elongation at break 312%. Also the material showed excellent antifatigue and reliable chemical properties. CONCLUSION: The optimal condition of crosslinking modification of UHMWPE is 75 kGy irradiation after 150 °C heat treatment.

[COMPUTER ASSISTED DESIGN AND ELECTRON BEAMMELTING RAPID PROTOTYPING METAL THREE-DIMENSIONAL PRINTING TECHNOLOGY FOR PREPARATION OF INDIVIDUALIZED FEMORAL PROSTHESIS].

OBJECTIVE: To study the feasibility of preparation of the individualized femoral prosthesis through computer assisted design and electron beammelting rapid prototyping (EBM-RP) metal three-dimensional (3D) printing technology. METHODS: One adult male left femur specimen was used for scanning with 64-slice spiral CT; tomographic image data were imported into Mimics15.0 software to reconstruct femoral 3D model, then the 3D model of individualized femoral prosthesis was designed through UG8.0 software. Finally the 3D model data were imported into EBM-RP metal 3D printer to print the individualized sleeve. RESULTS: According to the 3D model of individualized prosthesis, customized sleeve was successfully prepared through the EBM-RP metal 3D printing technology, assembled with the standard handle component of SR modular femoral prosthesis to make the individualized femoral prosthesis. CONCLUSION: Customized femoral prosthesis accurately matching with metaphyseal cavity can be designed through the thin slice CT scanning and computer assisted design technology. Titanium alloy personalized prosthesis with complex 3D shape, pore surface, and good matching with metaphyseal cavity can be manufactured by the technology of EBM-RP metal 3D printing, and the technology has convenient, rapid, and accurate advantages.

[Improvement of the the thermostability of Penicillium expansum lipase by mutagenesis the random mutant ep8 at K55R].

In order to improve the thermostability of the Penicillium expansum Lipase (PEL), the lipase encoding genes was mutated by site-directed mutagenesis. A recombinant vector pAO815-ep8-K55R which contain double mutant genes was constructed by overlap extension PCR using the cDNA of a random-mutant lipase ep8 (a single site mutant) as the template and two special primers were used to generate another mutation site K55R. The recombinant vector was transformed into Pichia pastoris GS115 by electroporation and the recombinant mutant GS-pAO815-ep8- K55R can secret double-mutant lipase PEL-ep8-K55R-GS into the medium when it was induced by Methanol. The yield of the double-mutant lipase is 508 u/mL, which is 81% that of the wild type lipase PEL-GS (627 u/mL) and 55% that of random-mutant PEL-ep8-GS (924 u/mL). The specific activity of double-mutant lipase is 2309.1 u/mg, which is similar to random-mutant lipase PEL-ep8-GS and the wild type lipase PEL-GS. The optimum temperature of the double-mutant lipase is same with the wild type lipase PEL-GS and random-mutant lipase PEL-ep8-GS. While the Tm of the double-mutant lipase is 41.0 degrees C, 2.3 degrees C higher than the wild type lipase PEL-GS and 0.8% higher than the random-mutant lipase PEL-ep8-GS, indicating that the double-mutant lipase PEL-ep8-K55R-GS has higher thermostability.