Electromechanical Effects of Bone Remodeling Based on Edge Smoothed Finite Element Method / 医用生物力学

Objective Aiming at solving the problem of poor accuracy for numerical solution of traditional finite element method (FEM) in numerical analysis on piezoelectric effects of bone remodelling, a model with an edge-based smoothed FEM (ES-FEM) was proposed. Methods The bone model was discretized by triangular elements, and the smoothing domain was constructed based on edges of the existing mesh element. Based on gradient smoothing technique, the smoothed strain gradient and the smoothed electric field gradient were obtained, and the discrete equations of the system were constructed under the framework of smoothed Galerkin weakform. Results The changes of bone mineral density (BMD) and the distributions of electric potential under piezoelectric effects in the process of bone remodelling were reflected by using the above model. Compared with FEM, ES-FEM could improve the accuracy of simulation result for bone remodelling to a certain extent. Conclusions The proposed ES-FEM can simulate the process of bone remodelling more accurately. The accurate prediction for piezoelectric effect of bone reconstruction by this method provides an effective theoretical basis for clinical research of bone diseases.

Occurrence of deep venous thrombosis in adult burn patients and its risk factors / 中华烧伤杂志

Objective@#To investigate the occurrence and risk factors of deep venous thrombosis (DVT) in adult burn patients.@*Methods@#The clinical data of 1 219 adult burn patients admitted to the Department of Burns of Zhengzhou First People′s Hospital from January 1, 2015 to August 31, 2016, conforming to the study criteria, were analyzed retrospectively by the method of case-control study, including 811 males and 408 females, aged 18-102 years. According to whether DVT occurred during hospitalization or not, the patients were divided into group DVT (n=12) and non-DVT group (n=1 207). The incidence of DVT, the diagnosis time of DVT, affected limbs, and DVT classification were counted and recorded. The gender, age, total burn area, D-dimer, lower limb burn, full-thickness burn, femoral vein indwelling central venous catheter (CVC) , inhalation injury, sepsis/infection shock, surgical operation, and infusion of concentrated red blood cells of patients between the two groups were compared with chi-square test, and then the indicators with statistically significant differences between the two groups were processed by multivariate binary logistic regression analysis to screen the independent risk factors of DVT in the adult burn patients.@*Results@#(1) The incidence of DVT of adult burn patients was 0.98% (12/1 219), and DVT was diagnosed 24-138 days after injury, with a median of 61.5 days. DVT occurred in the right lower limb of 2 patients, left lower limb of 8 patients, and bilateral lower limbs of 2 patients, and DVT classification included 6 cases of mixed type and 6 cases of peripheral type. (2) There were no statistically significant differences in gender, age, and full-thickness burn of patients between the two groups ( χ2=1.524, 0.021, 3.115, P>0.05). There were statistically significant differences in total burn area, lower limb burn, inhalation injury, sepsis/infection shock, D-dimer, femoral vein indwelling CVC, surgical operation, and infusion of concentrated red blood cells among patients between the two groups (χ2=17.975, 6.206, 3.987, 8.875, 5.447, 15.124, 10.735, 14.031, P<0.05 or P<0.01). (3) Total burn area, D-dimer, and femoral vein indwelling CVC were independent risk factors for DVT in adult burn patients (odds ratio=10.927, 4.762, 9.394, 95% confidence interval=3.078-38.789, 1.197-18.934, 2.631-33.540, P<0.05 or P<0.01).@*Conclusions@#The incidence of DVT in adult burn patients is relatively low, and the diagnosis time of DVT is 3 weeks after burn, with DVT classification of mixed type and peripheral type. The total burn area, femoral vein indwelling CVC, and D-dimer are independent risk factors for predicting DVT in adult burn patients.

Synthesis and identification of nanosilver-hybridized PLGA microsphere loaded with simvastatin / 国际生物医学工程杂志

Objective:To prepare nanosilver-hybridized polylactic acid-glycolic acid copolymer (PLGA) microspheres loaded with simvastatin (SIM), and to evaluate its sustained release effect in vitro. Methods:The emulsification-solvent evaporation method was used to prepare SIM-loaded PLGA microspheres. Silk fibroin (SF) was used to modify the surface of SIM-loaded PLGA microspheres by hydrophobic interaction. Then, the microspheres were continually modified by electrostatic adsorption to chitosan (CTS) and nano-silver (AgNPs) to prepare SF-AgNPs-CTS-SF-SIM-PLGA microspheres. Scanning electron microscope, Fourier transform infrared spectrometer, energy spectrometer, Zeta potential meter were used to analyze the SIM-loaded microspheres. The external release properties of the SIM-loaded microspheres were also investigated.Results:The average diameter of the prepared PLGA microspheres was about 9.67 μm. The results of Fourier transform infrared spectroscopy and energy spectroscopy showed that the AgNPs-CTS-SF-SIM-PLGA microspheres have been successfully constructed. The Zeta potential results indicated that the SIM-loaded microspheres were all in a stable state. The in vitro release results showed that the SF-AgNPs-CTS-SF-SIM-PLGA microspheres had a good in vitro release effect, could delay the drug release rate and prolong the drug release time. Conclusions:The SF-AgNPs-CTS-SF-SIM-PLGA microspheres have antibacterial and osteogenic effects, and exhibit a good in vitro release effect. They can be used for local sustained-release administration in the oral cavity, which make makes them potentially useful in the treatment of periodontitis.

Interventional therapy of deep venous thrombosis of lower limb after burn: initial experience in 13 cases / 介入放射学杂志

Objective To discuss the curative effect and specificity of interventional therapy for deep venous thrombosis (DVT) of lower limb in burned patients.Methods The clinical data of 13 patients with lower limb DVT after burn,including 7 males and 6 females with a median age of 46.1 years (37-67 years),were retrospectively analyzed.The causes of burn included flame burn (n=9),electric injury (n=2) and hydrothermal bum (n=2).The burned area was 1％-88％ of the total body surface,with a mean of (37.08± 30.60) ％.Lower limb DVT complicated by lower limb bum was observed in 11 patients,among them bum of both lower limbs was seen in 8 patients.Lower limb DVT associated with inhalation injury was found in 5 patients.Clinically,lower limb DVT was usually detected in 13-72 days after burn,with a mean of (38.69± 16.83) days.Interventional treatment was carried out in all 13 patients,and the curative effect was assessed.Results Technical success of interventional treatment was obtained in all 13 patients.Both inferior vena cava filter placement via right internal jugular vein approach (n=3) or via unaffected-side femoral vein approach (n=10) and anticoagulant therapy were conducted.Catheter-directed thrombolysis was employed in 7 patients,intravenous thrombolysis was adopted in 4 patients,and no thrombolysis therapy was used in 2 patients.No pulmonary embolism occurred.The curative effect rate of interventional treatment was 84.6％(11/ 13).Conclusion For the treatment of lower limb DVT after burn,interventional therapy is safe and reliable,but the selection of puncture site and the use or not use of indwelling catheter for thrombolysis should be carefully taken into consideration.

LRIG1 Enhances Chemosensitivity by Modulating BCL-2 Expression and Receptor Tyrosine Kinase Signaling in Glioma Cells

PURPOSE: Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) are an inhibitor of receptor tyrosine kinases (RTKs) that was discovered in recent years, and many studies showed that LRIG1 is a tumor suppressor gene and may be related to tumor drug resistance. In this study, we explored whether LRIG1 protein expression can improve the chemosensitivity of glioma cells and what was its mechanism. MATERIALS AND METHODS: We collected 93 cases of glioma tissues and detected the expression of LRIG1 and BCL-2. We constructed a multidrug resistance cell line U251/multidrug resistance (MDR) and examined the change of LRIG1 and BCL-2 at mRNA and protein expression levels. LRIG1 expression was upregulated in U251/MDR cells and we detected the change of multidrug resistance. Meanwhile, we changed the expression of LRIG1 and BCL-2 and explored the relationship between LRIG1 and BCL-2. Finally, we also explored the relationship between LRIG1 and RTKs. RESULTS: LRIG1 was negatively correlated with BCL-2 expression in glioma tissue and U251/MDR cells, and upregulation of LRIG1 can enhance chemosensitivity and inhibit BCL-2 expression. Furthermore, LRIG1 was negatively correlated with RTKs in U251/MDR cells. CONCLUSION: These results demonstrated that LRIG1 can improve chemosensitivity by modulating BCL-2 expression and RTK signaling in glioma cells.

Glioma Stem Cell-Targeted Dendritic Cells as a Tumor Vaccine Against Malignant Glioma

PURPOSE: Cancer stem cells have recently been thought to be closely related to tumor development and reoccurrence. It may be a promising way to cure malignant glioma by using glioma stem cell-targeted dendritic cells as a tumor vaccine. In this study, we explored whether pulsing dendritic cells with antigens of glioma stem cells was a potent way to induce specific cytotoxic T lymphocytes and anti-tumor immunity. MATERIALS AND METHODS: Cancer stem cells were cultured from glioma cell line U251. Lysate of glioma stem cells was obtained by the repeated freezing and thawing method. Dendritic cells (DCs) were induced and cultured from the murine bone marrow cells, the biological characteristics were detected by electron microscope and flow cytometry. The DC vaccine was obtained by mixing DCs with lysate of glioma stem cells. The DC vaccine was charactirizated through the mixed lymphocyte responses and cell killing experiment in vitro. Level of interferon-gamma (IFN-gamma) in the supernatant was checked by ELISA. RESULTS: After stimulation of lysate of glioma stem cell, expression of surface molecules of DC was up-regulated, including CD80, CD86, CD11C and MHC-II. DCs pulsed with lysate of glioma stem cells were more effective than the control group in stimulating original glioma cells-specific cytotoxic T lymphocytes responses, killing glioma cells and boosting the secretion of IFN-gamma in vitro. CONCLUSION: The results demonstrated DCs loaded with antigens derived from glioma stem cells can effectively stimulate naive T cells to form specific cytotoxic T cells, kill glioma cells cultured in vitro.