Effects of carboxymethyl chitosan on the blood system of rats.

Carboxymethyl chitosan (CM-chitosan), a derivative of chitosan, was extensively studied in the biomedical materials field for its beneficial biological properties of hemostasis and stimulation of healing. However, studies examining the safety of CM-chitosan in the blood system are lacking. In this study CM-chitosan was implanted into the abdominal cavity of rats to determine blood indexes at different times and to evaluate the effects of CM-chitosan on the blood system of rats. Coagulation function was reflected by thrombin time (TT), prothrombin time (PT), activated partial thromboplatin time (APTT), fibrinogen (FIB) and platelet factor 4 (PF4) indexes; anti-coagulation performance was assessed by the index of antithrombinIII (ATIII); fibrinolytic function was reflected by plasminogen (PLG) and fibrin degradation product (FDP) indexes; and blood viscosity (BV) and plasma viscosity (PV) indexes reflected hemorheology. Results showed that CM-chitosan has no significant effects on the blood system of rats, and provides experimental basis for CM-chitosan to be applied in the field of biomedical materials.

Construction of multi-layered Zn-modified TiO2 coating by ultrasound-auxiliary micro-arc oxidation: Microstructure and biological property.

Surfaces with desirable cytocompatibility and bactericidal ability are favoured for orthopaedic implants to stimulate osteogenic activity and to prevent implant-associated infection. In this work, we creatively introduce ultrasonic vibration (UV) to micro-arc oxidation (MAO) process and explore its influence on the microstructure, corrosion property and biological responses of Zn-modified TiO2 coating. With the introduction of UV, a uniform surface layer with homogeneously-distributed clusters could be produced as the outer layer, which possesses a fusion band with the underlying TiO2. The microstructural modification associated with UV results in the enhanced corrosion resistance, increased adhesive strength and improved biological performances of the resultant coating relative to that with the absence of UV. Hence, the ultrasonic auxiliary micro-arc oxidation (UMAO) is regarded as a promising surface modification method to produce Ti-based orthopaedic implants of high quality.

Cell Catalysis of Citrate to Itaconate by Engineered Halomonas bluephagenesis.

Itaconic acid (IA), an important five-carbon unsaturated dicarboxylic acid, is one of the top 12 renewable chemicals with an urgent need to reduce industrial production costs. Halomonas bluephagenesis, which possesses the potential for cost-effective bioproduction of chemicals and organic acids due to its ability to grow under open nonsterile conditions and high tolerance to organic acid salts, was genetically engineered and used to produce IA from citrate by a cell catalytic strategy. Here, two essential genes (cis-aconitate decarboxylase encoding gene cadA and aconitase (ACN) encoding gene acn) were introduced into H. bluephagenesis to construct an IA biosynthesis pathway. Further engineering modifications including coexpression of molecular chaperones GroESL, increasing the copy number of the gene encoding rate-limiting enzyme ACN, and weakening the competing pathway were implemented. Under the optimized condition for the cell catalytic system, the engineered strain TAZI-08 produced 451.45 mM (58.73 g/L) IA from 500 mM citrate, with 93.24% conversion in 36 h and a productivity of 1.63 g/(L h). An intermittent feeding strategy further increased the IA titer to 488.86 mM (63.60 g/L). The IA titer and citrate conversion in H. bluephagenesis are the highest among heterologous hosts reported so far, demonstrating that this strain is a suitable chassis for hyperproduction of IA.

Synthesis, microstructure, anti-corrosion property and biological performances of Mn-incorporated Ca-P/TiO2 composite coating fabricated via micro-arc oxidation.

In this work, a Mn-incorporated Ca-P/TiO2 composite coating was produced through the facile one-step micro-arc oxidation (MAO) method. It is revealed that only when the concentration of Na2Mn-EDTA reaches 0.02 mol/L, the Ca-P phase could form on Mn-incorporated TiO2 coating, which is associated with the combined effect of EDTA complex and Mn species. The Ca-P phase is amorphous, which may contain hydroxyapatite phases whereas the underlying Mn-incorporated TiO2 coating contains two separate layers, including the Mn-rich outer layer and Mn-depleted inner layer. The biological investigation of the Mn-incorporated Ca-P/TiO2 composite coating suggests that it exhibits desirable osteogenesis with certain capability to inhibit the growth of S. aureus bacteria. Hence, a promising composite coating with superior bone formability could be produced using the one-step micro-arc oxidation method in the electrolyte containing Na2Mn-EDTA.

[Effect of NF-κB on the expression of interleukin-6 induced by lipopolysaccharides of Porphyromonas endodontalis in MC3T3-E1 cells].

PURPOSE: To investigate the effect of NF-κB signaling on the expression of interleukin-6(IL-6) induced by lipopolysaccharides(LPS) extracted from Porphyromonas endodontalis(P.e) in MC3T3-El cells. METHODS: MC3T3-E1 cells were pretreated with BAY-117082 for 1 h, and then were treated with 10 mg/L P.e-LPS for different times. The translocation of NF-κB was observed by immunofluorescence. The expression of IL-6 was detected by reverse transcription polymerse chain reaction (RT-PCR) and enzyme-linked immuno sorbent assay (ELISA). Statistical analysis was performed using multi-way ANOVA and Dunnett's t test with SPSS 13.0 software package. RESULTS: The staining of NF-κB was mostly in cytoplasm in untreated cells. Rapid translocation of NF-κB into nucleus was observed in the cells stimulated for 30 min and mostly relocalization of NF-κB from nucleus to cytoplasm was observed after 60 min. Pretreatment with 10 µmol/L BAY-117082 for 1h significantly inhibited P.e-LPS-induced translocation of NF-κB .The mRNA and proteins of IL-6 decreased significantly after pretreatment with 10 µmol/L BAY-117082 and the expression of IL-6 proteins was reduced from (774.983±6.585) ng/L to (377.384±14.620) ng/L (P<0.01). The group of treatment with BAY-117082 alone had no significant difference from the blank control group. CONCLUSIONS: P.e-LPS can induce translocation of NF-κB in mouse osteoblast MC3T3-El, and P.e-LPS may induce the expression of IL-6 in mouse osteoblast through the signaling of NF-κB.

[Animal experimental study of biodegradable magnesium alloy stapler for gastrointestinal anastomosis].

OBJECTIVE: To explore the safety and feasibility of biodegradable magnesium alloy stapler based on the result of animal experimental study for gastrointestinal anastomosis. METHODS: Sixteen beagle dogs were equally and randomly divided into experimental (magnesium alloy) group and control (titanium alloy) group. A gastrojejunal and a colonic anastomosis were performed in each beagle dog. The anastomosis time, postoperative complications, body weight, blasting pressure of anastomosis and serum glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, creatinine, blood urea nitrogen, and serum magnesium were compared between the two groups. The healing of anastomosis and degradation of magnesium alloy were observed. The histopathological features of heart, liver, spleen and kidney were examined in the two groups. RESULTS: There were no significant differences in anastomosis time, body weight, postoperative complications, anastomotic bursting pressure between the two groups. The anastomosis was healed well, and no dramatic inflammatory cell infiltration was observed. Magnesium alloy could be degraded completely in the animal body within 90 days. There were no significant differences in serum glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, creatinine, blood urea nitrogen and serum magnesium between the two groups. Histopathological examination showed that the degradation of magnesium alloy did not harm the important organs (liver, kidney, heart, brain and spleen). CONCLUSIONS: Magnesium alloy stapler is safe and feasible for gastrointestinal anastomosis in beagle dogs. The degradation of magnesium alloy does not harm the healing of anastomosis and other important organs. Magnesium alloy stapler may be a candidate of biodegradable and safe material of stapler for gastrointestinal anastomosis in human.

[Effect of lipopolysaccharides extracted from Porphyromonas endodontalis on the expression of p38 and ERK1/2 in osteoblast].

PURPOSE: To investigate the effect of lipopolysaccharides (LPS) extracted from Porphyromonas endodontalis(P.e) on the expression of p38 and ERK1/2 in osteoblast. METHODS: MC3T3-E1 cells were stimulated with 10 µg/mL P.e-LPS for 0,5,15,30,60,180 min. The phosphorylation of p38 and ERK1/2 was measured by Western blot. Statistical analysis was performed using one- way ANOVA and Dunnett t test with SPSS11.0 software package. RESULTS: 10 µg/mL LPS could significantly activate p38 MAPK. The peak of phosphorylated p38 was detected at 5 to 30 min(P<0.01) and returned to baseline within 60 min; the level of phosphorylated ERK1/2 increased after the stimulation of LPS for 5 min and reached maximum at 15 min (P<0.01) and declined after 30 min. CONCLUSIONS: P.e-LPS can induce the expression of p38 and ERK1/2 in osteoblast MC3T3-E1, which indicates that P.e-LPS may play an important role in osteoblast through p38 and ERK1/2.

[Effects of lipopolysaccharides from various Porphyromonas on the expression of CD14 and TLRs in mouse osteoblast].

PURPOSE: To observe the effect of lipopolysaccharides(LPS) extracted from Porphyromonas endodontalis(P.e) and Porphyromonas gingivals(P.g) on the expression of CD14 and TLRs in osteoblast. METHODS: MC3T3-E1 cells were stimulated with 10µg/mL P.e-LPS and P.g-LPS. The change of CD14,TLR2 and TLR4 mRNA was observed at different time point (0,1,3,6,12,24h) using RT-PCR,and the expression of CD14,TLR2 and TLR4 protein was measured by flow cytometry at 24-hour. Statistical analysis was performed using one-way ANOVA and Dunnett t test with SPSS11.0 software package. RESULTS: MC3T3-E1 cells were stimulated with 10µg/mL P.e-LPS for 1h,the expression of CD14 and TLR4 mRNA increased significantly. There was no increase of TLR2 mRNA with stimulation of P.e-LPS. The CD14,TLR2 and TLR4 mRNA expression increased significantly after stimulation with 10µg/mL P.g-LPS. Flow cytometry showed that CD14 and TLR4 protein increased significantly after stimulation with 10µg/mL P.e-LPS. CD14,TLR2 and TLR4 protein increased significantly after treatment with 10µg/mL P.g-LPS. CONCLUSIONS: CD14,TLR4 receptors are involved in P.e-LPS effect and CD14,TLR2 and TLR4 receptors are involved in P.g-LPS effect in mouse osteoblast.