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BACKGROUND: Micro-arc oxidation (MAO) treatment can improve the biological properties of titanium alloy implants. Previous studies mostly focused on the evaluation of titanium alloy plate, while the effects of the MAO-modified 3D titanium scaffold on the cell growth and differentiation were rarely reported. OBJECTIVE: To investigate the effect of MAO coating on the biological performance of cells seeded onto the 3D-printed porous titanium alloy scaffold. METHODS: Rat bone marrow mesenchymal stem cells were seeded onto the MAO-modified Ti6Al4V alloy scaffolds (experimental group) and unmodified scaffolds (control group). After 4 and 7 days of culture, cell/scaffold constructs were retrieved and processed for the assessment of cell morphology by using scanning electron microscopy, cytoskeletal staining analysis and cell viability assay were also evaluated. At 4, 7 and 11 days of culture, the levels of alkaline phosphatase and osteocalcin in the cell supernatant were detected. At 1, 4, 7 and 11 days of culture, the cell proliferation rate was measured using the MTT assay. RESULTS AND CONCLUSION: (1) At 4 and 7 days of culture, live/dead staining showed that the bone marrow mesenchymal stem cells grew well on the two kinds of scaffolds. The analysis of cytoskeleton staining showed that the cytoskeleton of the experimental group was stereo and polygonal, while the cells on the scaffold surface in the control group were flat and spindle-shaped, spreading along the macro structure of the scaffolds. Under the scanning electron microscopy, the cells in the experimental group arranged closely and spread in a good condition, with interconnected lamellipodia and filopodia that firmly adhered to the scaffold surface in an anchor-shaped structure; in the control group, less filopodia interconnected, less extracellular matrix, and flat and sheet-like cells were observed. (2) With the time increase, the levels of alkaline phosphatase and osteocalcin increased gradually in both groups. The alkaline phosphatase level in the experimental group was significantly higher than that in the control group at 7 and 11 days of culture (P < 0.05), while the osteocalcin level was higher in the experimental group than the control group at 11 days of culture (P < 0.05). (3) With the prolongation of culture time, the number of cells in the two groups increased gradually. The number of cells cultured in the experimental group was significantly higher than that in the control group at 7 and 11 days of culture (P < 0.05). To conclude, the MAO-modified titanium alloy scaffold is favorable for cell adhesion, proliferation and differentiation.
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Objective:To explore the influence of high altitude hypoxia on the phagocytosis and killing functions of peritoneal macrophages in mice by establishing mouse model in high altitude hypoxic environment.Methods:①After exposure of mice to an altitude of 4 200 m,2 200 m and 400 m for 30 d respectively,flow cytometry was used to detect the phagocytosis and killing functions of peritoneal macrophages on staphylococcus aureus labeled with FITC.②The respiratory burst level of the cultured macrophage in mice was detected in 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescent probe method. ③The concentration of NO2- as a stable oxidative metabolite of NO in the supernatant of the cultured macrophages was measured with ELISA kits;④The release level of IL-6 and TNF-α in the cultured mice macrophage supernatant was also determined with ELISA kits.Results:After exposed under high altitude hypoxia for 30 d,compared with the control group (400 m),the phagocytosis,respiratory burst level and NO release in high altitude groups (4 200 m and 2 200 m) were all than those in the control group(400 m) (P<0.05).While the concentration of IL-6 and TNF-α in the Mφ cultured supernatant showed an obvious increase (P<0.05).Conclusion:Exposure under high altitude hypoxia (at altitude of 4 200 m and 2 200 m) for 30 d compromised the phagocytosis and oxygen dependent cytolyticactivity functions,and also raised the cytokines secretion level of IL-6 and TNF-α in Mφ,thereby affecting the innate immune response ability of Mφ in body.
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The 3,4-Dichlorobenzotrifluoride (3,4-DCBTE) was dehalogenated with oxidation treatment by heterogeneous Fenton-like system, using nanoscale Fe304/CeO2 as a catalyst. This nanoscale catalyst was prepared by the impregnated method. As a highly active new heterogeneous Fenton-like catalyst, nanoscale Fe304/CeO2 not only has the characteristics of the traditional Fenton-like catalyst but also can prevent the secondary pollution which caused by Fe2+. To find the optimum catalytic conditions for nanoscale Fe3O4/CeO2, the influence factors were investigated. The results indicated that the degradation ratio of 3,4-DCBTE was significantly improved by adding nanoscale Fe3O4/CeO2, with the removal ratio reaching 97.76% in 120 minutes and 79.85% in 20 minutes. As the temperature increasing, the catalytic effect of nanoscale Fe3O4/CeO2 catalyst had been constantly improved obviously. As the pH decreased, the degradation ratio of 3,4-DCBTE increased. With the increase of dosage of hydrogen peroxide (H2O2), the degradation efficiency of 3,4-DCBTE initially increased and then decreased, because oxygen (O2) was generated in preferential self-reaction when an excess of (H2O2) was added. The optimum removal efficiency was observed with the dosage of 15 mg x L(-1). With the increased amount of catalyst, there was a same trend as dosage of hydrogen peroxide (H2O2). The degradation ratio of 3,4-DCBTE initially increased and then decreased, the optimum amount of catalyst was 0.5 g x L(-1). The results also suggested that the reaction process followed the first-order kinetics and the thermodynamic analysis demonstrated that the reaction was only needed low reaction activation energy.