[Effect of sodium alginate-g-deferoxamine/chitosan microspheres on osteogenic differentiation of rat bone mesenchymal stem cells].

PURPOSE: To explore the effect of sodium alginate-g-deferoxamine/chitosan (SA-g-DFO/CS) microspheres on proliferation and osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs). METHODS: A kind of SA-g-DFO/CS microsphere was developed through electrostatic interaction between porous chitosan microspheres and sodium alginate chemically grafted on the surface of DFO. Its morphology, porosity rate, pore size and sustained release of DFO in vitro were examined. Rat BMSCs were isolated and co-cultured with microspheres in osteogenic differentiation medium. MTT assay was used to study the influence of cell proliferation, and Calcein-AM/PI staining was used to observe the cell viability. Alkaline phosphatase (ALP) activity assay was conducted. PCR was used to detect the expression of genes related to angiogenesis and osteogenesis. Statistical analysis was performed using SPSS 22.0 software package. RESULTS: The SA-g-DFO/CS porous microspheres were successfully prepared with a sustained re6lease of DFO. Compared with SA/CS microspheres, the SA-g-DFO/CS microspheres were conducive to cell proliferation and differentiation, with the increases in expression level of ALP, related angiogenesis genes HIF-1α, VEGF and osteogenesis genes COLI, OCN. CONCLUSIONS: The SA-g-DFO/CS porous microspheres can provide a new choice for the development of alveolar bone regeneration.

[Nitrogen Metabolism and Flora Characteristics of Bacteria Algae Complex System].

In order to denitrify the urban tail water deeply and control the eutrophication of surface water, the molecular biology methods were used to study the nitrogen metabolism performance of the denitrification complex flora and the algal-bacteria symbiotic system. The results showed that the nitrogen metabolism complex flora was high ammonification and denitrification performance. The removal effect of ammonia nitrogen of group JZ was very well in urban tailwater, and the degradation rate was as high as 95%. The removal effect of total nitrogen of group JZ was better than that of group J in the experimental water distribution. High-throughput sequencing showed that the main dominant flora and proportion of group J were Firmicutes 44.53%, Proteobacteria 43.41%, Actinobacteria 5.37%, Bacteroidetes 3.04%, and Chloroflexi 1.35%. The main dominant bacterial groups in the group JZ were 33.89% Cyanobacteria, 25.34% Chloroflexi, 19.38% Proteobacteria, 10.02% Firmicutes, and 4.20% Acidobacteria. The dominant species in group J were compared with those in group JZ; the proportions were 82% and 18% in Firmicutes, 69% and 31% in Proteobacteria, 1% and 99% in Cyanobacteria, 5.1% and 95% in Chloroflexi, 73% and 27% in Actinobacteria. It was concluded that the removal effect of ammonia nitrogen of group JZ was high in the urban tailwater. With the addition and growth of Micrococcus in group J, the nitrogen metabolism flora in group JZ changed accordingly, so as to adapt to the environment in which the dominant algae formed. It forms a new nitrogen metabolism system of bacteria and algae with Micrococcus. This research provides a theoretical and data basis for the application of algal-bacterial co-metabolism systems.

[Effects of Water Supply Quality and Social Activity on the Microbial Community in Baiyangdian Wetland].

To clarify the impact of water quality and social activity in the Baiyangdian wetland on the biological community, the change characteristics of bacterial, fungal, and archaeal communities in different areas of the Dian District were studied. Samples were collected at the entrance of Fuhe District (NBB), tourist areas with frequent human social activities (NBD), residential breeding areas (NBX), and village sparse areas (NBN). The physical and chemical characteristics and biological communities of the samples were evaluated. The results of the study show that the COD concentration of organic pollutants in the NBB was 12.35 mg·L-1, and the total nitrogen concentration was 10.12 mg·L-1, that the concentration was highest. Moreover, the water quality in NBD and NBX was better than that of NBB. The NBN area exhibited the best water quality, with COD and total nitrogen concentration values of 6.9 mg·L-1 and 1.82 mg·L-1, respectively. Many types of NBB bacteria were recorded, with a diversity index of 5.86, and NBN diversity index exceeding 4.78. The dominant bacterial flora in all samples was the Proteobacteria, which accounts for 68.8% of the total bacterial communities in NBN samples. The diversity index of fungi in NBB was only 2.14. There were many types of fungi in NBN, with a diversity index of 3.23. Chytridiomycota was found in the NBD and NBN, accounting for 5.4% and 9.8% of the total number of fungi, respectively. The Chytridiomycota was main decomposer of hard to degrade organic carbon. The diversity of archaea of NBN was the lowest among all the samples. Crenarchaeota was the dominant phylum, which accounts for 39.0%, 51.9%, 47.3%, and 30.1% of NBB, NBD, NBX, and NBN samples, respectively. The number of Halobacterota was lower than Crenarchaeota. The main factor of eutrophication and microbial community changes in Baiyangdian wetland was the results of the combined action of external and internal pollution. Both external and internal pollution increased the organic matter, nitrogen and phosphorus content in the water, and the microbial community structure has changed significantly. The contents of organic matter, nitrogen, and phosphorus in water were increased and the microbial community structures were changed significantly by the increase of both external and internal pollution.

[The role of Bmal1 in regulating the aging of mesenchymal stem cells via Wnt/ß-catenin signaling pathway].

PURPOSE: To investigate whether Bmal1 and Wnt/ß-catenin signaling pathway has synergistic or antagonistic effects on the aging of mouse bone marrow-derived mesenchymal stem cells (BMSCs). METHODS: The cells were divided into two groups. The expression of ß - catenin and TCF1 in the transfected group and the blank group were detected by real-time fluorescent quantitative PCR and Western blot. The data were statistically analyzed using SPSS 19.0 software package. RESULTS: Recombinant Bmal1 lentiviral vector was successfully constructed. The expression of ß-catenin was enhanced after Bmal1 was transfected(P<0.05), which was different from that of TCF1. There was no significant difference in TCF1. CONCLUSSIONS: Bmal1 has a synergistic effect on the aging changes of MSCs in mice directly or indirectly regulated by Wnt/ß-catenin signaling pathway.

[Comparative study of enamel discoloration related to bonding with different orthodontic adhesives and cleaning-up with different procedures].

PURPOSE: The aim of this study was to compare if there was any difference in the enamel discoloration after staining when three orthodontic adhesives and 4 enamel clean-up methods were tested. METHODS: Three types of orthodontic adhesives were used: chemically cured resin, light-cured resin and resin-modified glass-ionomer cement. A total of 120 human extracted premolars were included. Ten teeth of each orthodontic adhesive were randomly cleaned-up with 1 of 4 different procedures and stained in coffee for 7 days: carbide bur (TC), carbide bur and Sof-Lex polishers (TC＋SL), carbide bur and One Gloss polishers (TC＋OG), carbide bur and PoGo polishers (TC＋PG). Colour measurements were made with Crystaleye dental spectrophotometer at baseline and after storage in a coffee solution for 1 week. Two way ANOVA and Bonferroni test were used for statistical analysis with SPSS 13.0 software package. RESULTS: The colour change values of adhesive materials in the TC group were the greatest. The lowest ΔE* values were obtained from the TC＋SL group. However, there was no significant difference between the TC＋SL and TC＋PG group (P>0.05). The resin-modified glass-ionomer cement group showed the lowest colour differences and chemically cured resin group showed the highest ΔE* values among all orthodontic adhesives (P<0.05). CONCLUSIONS: The colour change of enamel surface is affected by the type of adhesive materials and clean-up procedures.

[Effects of different resin removal methods on shear bond strength of rebonded orthodontic brackets].

PURPOSE: To compare the shear bond strength (SBS) of rebonded orthodontic metal brackets with different resin removal methods. METHODS: Forty extracted premolars were chosen as samples and divided into 4 experimental groups. The teeth were bonded with brackets. The brackets from 3 groups were debonded while adhesive remnants were removed from bracket bases by methods of grinding, sandblasting, and direct flaming, respectively and then rebonded. The SBS values of all rebonded brackets were determined after pH cycling experiment for 30 days. Some rebonded bracket bases were selected and observed under scanning electron microscope (SEM). The data was analyzed by one-way ANOVA test using SPSS 13.0 software package. RESULTS: Statistical analysis revealed a significant difference of SBS values among the 4 experimental groups (P<0.05). The SBS values of the group by direct flaming was significantly lower compared to the other groups (P<0.05). There was no significant difference of SBS values among the other groups. CONCLUSIONS: The rebonded brackets after resin removal by grinding and sandblasting have a similar SBS compared to the initial brackets adhesive.

[Clinical evaluation of glass fiber-reinforced composites for fixed orthodontic lingual retainers].

PURPOSE: The purpose of this clinical evaluation was to assess the clinical effect of application of everStick Ortho glass fiber-reinforced composites for orthodontic lingual retainer. METHODS: A total of 12 patients underwent orthodontic treatment using glass fiber-reinforced composites for fixed orthodontic lingual retainers. During a 24-month follow-up period after application of retainers, the condition of lingual retainers and the periodontal status were examined every 6 months. Gingival index and sulcus bleeding index were analyzed by nonparametric tests with SPSS 13.0 software package. RESULTS: During 24-month follow-up period, 11 orthodontic lingual retainers were stable without fracture while the periodontal tissue revealed no significant changes in all 12 patients. CONCLUSIONS: The application of everStick Ortho glass fiber-reinforced composites for orthodontic lingual retainer is a viable alternative to conventional retainer used in orthodontic treatment.

[Enamel surface roughness after interproximal enamel reduction with different methods in vitro].

PURPOSE: To assess the surface roughness after application of interproximal enamel reduction(IER) with different methods under a pH cycling experiment in vitro. METHODS: Thirty healthy premolars were used after removal for orthodontic reasons and divided into three groups. One proximal surface underwent IER as the experimental surface while the other was untreated as control. Each group underwent IER according to one of the following techniques: tungsten carbide bur and Sof-Lex disks (group 1); tungsten carbide bur and 10% maleic acid on Sof-Lex disk (group 2); tungsten carbide bur, Sof-Lex disks and fluor protector (group 3). All samples were treated using the pH cycling experiment everyday for 60 days. Enamel surface roughness value (Ra) was measured with profilemetry and morphology was observed under scanning electron microscopy (SEM). Statistical analysis was performed using SPSS 13.0 software package by means of paired t test or one way ANOVA. RESULTS: Ra of the experimental surface increased significantly than that of control in each group (P < 0.01). There was no significant difference among the experimental surfaces among the three groups (P > 0.05). SEM images demonstrated that enamel surfaces were smoother in the group 2 and group 3 compared with the experimental surfaces in group 1. CONCLUSIONS: IER significantly increases surface roughness of the proximal enamel. The application of topical fluride on the enamel surface seems to be advantageous.

[The effect of different polishing methods on enamel after interproximal enamel reduction].

PURPOSE: The aim of this study is to compare the effect of the enamel demineralization degree after interproximal enamel reduction (IER) on extracted teeth with different polishing methods. METHODS: 20 extracted premolars were chosen as samples. In one premolar, a randomized approximal surface was selected as control surface while the other as experimental surface. After IER, the control surface was physically polished and the experimental surface was chemically polished. All samples were treated under the pH cycling experiment for 60 days. Then the enamel demineralization degree was measured with laser fluorescence diagnostic equipment. The data was analyzed by paired t test using SPSS10.0 software package. Some samples were selected to observe the enamel surface morphology through scanning electron microscope (SEM). RESULTS: The enamel demineralization degree of the control group increased significantly than that of the experimental group(P<0.01). SEM images demonstrated that the enamel surface was smoother in the experimental group than the control group. CONCLUSION: Compared with physical polishing,chemical polishing can increase the smooth degree of enamel surface and reduce the risk of enamel demineralization after IER.