Dynamic changes of inflammation in ligation-induced rat periodontitis model

Objective:To study the dynamic changes of inflammation in rat models of periodontitis induced by ligation.Methods:Twenty-one healthy male SD rats were selected and randomly divided into 7 groups,namely normal control group and ligation group A-F(the ligation group A-F were ligated 1,3,5,7,14 and 21 days respectively,and then sacrificed).In addition to the normal control group,ligature was used to ligate the neck of the right maxillary first molar.The experimental periodontitis model was established in rats.By observing the changes in rat body weight within 21 days,we explored the intervention of ligature wires on inflammation.The impact of the process,through monitoring the debris index simplified(DIS),Sulcus Bleeding Index(SBI),Tooth Mobility(TM),to evaluate the periodontal inflammation of the target tooth within 21 days of ligation.In addition,in order to more accurately assess the dynamic changes of the alveolar bone during the inflammatory phase,we use CBCT Observe the alveolar bone resorption.Results:The body weight of the ligation group decreased during the 3 days after ligation,and compared with the normal control group,there was no statistically significant difference in body weight growth rate in the ligation group from 3 to 21 days(P≥0.05),indicating that due to the intervention of the ligation wire,the rat will have a 3-day adaptability phenomenon.The ligation of silk after day will not affect the growth and development of rats.The DIS on the ligated side was higher than that of the normal control on the first,third,fifth,and seventh days after the ligation.The side increased significantly(P<0.05),and the DIS value increased in the first 3 days,and gradually decreased on the 5th day,until the 21st day after ligation,compared with the normal control group,the difference was not statistically significant(P≥0.05);SDI on the ligation side increased significantly on the 5th day,and gradually decreased after reaching the peak on the 7th day(P<0.05),until there was no statistical difference between the ligation side and the normal control group on the 21st day(P≥0.05);The day began to change and gradually increased until the 21st day,which was statistically significant compared with the normal control group(P<0.05);the CEJ-ABC distance of the ligation group A,B,and C was not statistically significant compared with the normal controlgroup(P>0.05),the CEJ-ABC distance of the ligated group D,E,and F was significantly higher than that of the normal control group(P<0.05),and bone resorption was more significant in group F compared with D and E groups(P<0.01).Conclusion:Three days after the ligation of the ligature,it affects the molar eating in rats,and induces inflammation.Ligation-induced experimental periodontitis is in the acute inflammatory phase during 3-7 days of ligation,and turns to chronic inflammatory phase in 14-21 days.Our study provides a more precise definition of the occurrence and development of ligation-induced periodontitis in rats,which provides a new direction for the subsequent study of periodontitis models and provides a basis for better and more accurate clinical research.

Platelet-rich fibrin-induced bone marrow mesenchymal stem cell differentiation into osteoblast-like cells and neural cells

Bone marrow mesenchymal stem cells were allowed to develop for 14 days in a platelet-rich fibrin environment.Results demonstrated that platelet-rich fibrin significantly promoted bone marrow mesenchymal stem cell proliferation.In addition,there was a dose-dependent increase in Runt-related transcription factor-2 and bone morphogenetic protein-2 mRNA expression,as well as neuron-specific enolase and glial acidic protein.Results showed that platelet-rich fibrin promoted bone marrow mesenchymal stem cell proliferation and differentiation of osteoblast-like cells and neural cells in a dose-dependent manner.

Calcium phosphate cements for bone engineering and their biological properties

Calcium phosphate cements （CPCs） are frequently used to repair bone defects. Since their discovery in the 1980s, extensive research has been conducted to improve their properties, and emerging evidence supports their increased application in bone tissue engineering. Much effort has been made to enhance the biological performance of CPCs, including their biocompatibility, osteoconductivity, osteoinductivity, biodegradability, bioactivity, and interactions with cells. This review article focuses on the major recent developments in CPCs, including 3D printing, injectability, stem cell delivery, growth factor and drug delivery, and pre- vascularization of CPC scaffolds via co-culture and tri-culture techniques to enhance angiogenesis and osteogenesis.

Enolic Schiff Base Zinc Amide Complexes： Highly Active Catalysts for Ring-Opening Polymerization of Lactide and ε-Caprolactone

A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-caprolactone, exhibiting notably high activity at ambient temperature, The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading （0.025 mol%） within 18 rain. The influence of various monomers as well as the polymerization mechanism have also been discussed.

Studies on Surface Properties and Cell Adhesion Properties of BSA Modified DBM Scaffold

As a scaffold material for bone tissue engineering, demineralized bone matrix(DBM) has such a limited ability to load cells and growth factors that the surface of the DBM scaffold was modified with bovine serum albumin(BSA) with different concentrations to improve the protein stmcture and physicochemical properties of the scaffold surface so as to enhance the adhesion of the cells. And the appropriate BSA concentration was explored. Compared with DBM, the scaffold with BSA coating had a smaller pore size and a lower porosity, also, the degradation rate was accelerated and the hydrophilic property was improved. Cells adhesion was observed inside the DBM seaffold before and after it had been modified, and the BSA modified scaffold had a good cell compatibility. Wlien the concentration of BSA was 20 mg/mL, the adhesion ability of the cells to modified scaffold was significantly increased, and the cell proliferation was facilitated.

Synthesis and Properties of PGS-Li Scaffold

Lithium ion-doped polyglycerol sebacate scaftbld（PGS）-Li was synthesized by adding lithium ions to po- lyglycerol sebacate（PGS） during its crosslinking process due to the specific effects of lithium ions on periodontal li- gament cells, cementoblasts and the eminent performance of PGS. The molecular mass, composition, structure, porosity, thermal properties, and hydrophilicity of the composite were characterized by gel permeation chromatogra- phy（GPC）, Fourier transform infrared spectroscopy（FTIR）, inductively coupled plasma optical emission spectrome- ter（ICP-OES）, scanning electron microscopy（SEM）, X-ray photoelectron spectroscopy（XPS）, thermogravimetric analyzer（TGA） and contact angle measurments, and the degradation of the material was evaluated by in vitro degra- dation experiments. The biological activity of PGS-Li scaffold was detected by calcein-AM staining and cytotoxicity test. The results indicate that PGS-Li scaffold has been successfully synthesized, which has similar composition and structure to PGS, but slightly larger molecular weight. In addition, the porosity and pore size of PGS-Li scaffold ba- sically meet the requirements of engineering scaffold materials and the seaffold shows better performance in terms of hydrophilicity and thermal stability than PGS. In vitro degradation experimental results show that the degradation rate of PGS-Li scaffold is higher than that of PGS. What＇s more, the results of cytotoxicity test and cell staining show that there is no significant difference in the proliferation and cell morphology of cementoblasts.

Synthesis of Novel Thiazoline Catalysts and Their Application in Michael Addition Reaction

Several novel chiral thiazoline catalysts containing thiazoline, thiourea and proline were efficiently synthesized from commercially available L-cysteine. These ligands were subsequently applied to the asymmetric Michael reaction between cyclohexanone and various β-nitrostyrene. The result shows that the optimal catalyst for this reaction is ligand 18d, the organocatalyst with thiazoline, thiourea and chiral proline motif, which efficiently promotes the enantioselective conjugate addition of cyclohexanone to various nitroalkenes to yield the corresponding addition products in high to excellent yields with enantiomeric excess（e.e.） up to 95% and diastereoselectivity ratio（dr.） up to 99：1.

Synthesis and Pharmacodynamics of Ibuprofen-l-acetoxyethyl Ester

lbuprofen（IBU） and its derivatives are widely used m treating many diseases, such as depression, glome- rulonephritis, fever caused by common cold or influenza, and rheumatoid arthritis. While in clinical trials, IBU was found to have many side effects. To weaken and prevent these side effects, a derivative called ibupro- fen-l-acetoxyethyl ester was synthesized in this paper. The maximum concentration（Cmax） in a shorter time was com- pared with IBU at the same dose.

Greener Gd-doped ZnAglnS3 Quantum Dots for Fluorescent and Magnetic Resonance Imaging Applications

The combination of fluorescent imaging and magnetic resonance imaging（MRI） techniques has attracted intense attention due to the complementary imaging ability of the two modalities. Optical imaging, especially fluorescence imaging, has good sensitivity, but poor tissue penetration ability, while MRI offers anatomical details and 3D information of soft tissue with high quality in a non-invasive manner. Therefore, MRI/fluorescence dual-imaging technique should have exciting clinical potential in some application fields.

Poly（L-lactide）-grafted Bioglass/Poly（lactide-co-glycolide） Scaffolds with Supercritical CO2 Foaming Reprocessing for Bone Tissue Engineering

The bioglass particles/poly（lactide-co-glycolide）（BG/PLGA） scaffold has been extensively explored for biomedical applications due to its excellent advantages of mechanical property and controllable degradation rate. In ottr previous studies, the BG nanoparticle sttrface-grafted with poly（L-lactide）（PLLA） could substantially improve the phase compatibility between the polymer matrix and the inorganic phase and the biocompatibility of the scaffolds. However, using the traditional preparation methods to prepare the composite scaffold can barely achieve a high po- rosity and porous connectivity. In this work, the PLLA-grafted bioglass/PLGA（g-BG/PLGA） scaffolds were prepared by supercritical carbon dioxide foaming（Sc-CO2） with before or after particulate leaching（PL） method（Sc-CO2-PL or PL-Sc-CO2 method, PL/Sc-CO2 methods） and their applications in bone replacement and tissue engineering were investigated. The porosities of the g-BG/PLGA scaffolds prepared by the PL/Sc-CO2 methods were higher than 90%, and their mechanical properties had similar values with human cancellous bone. The proliferations of osteoblasts on the scaffolds were dependent on different preparation methods. The PL/Sc-CO2 methods significantly increased the proliferations of the cells. Computed tomography（CT） three-dimensional（3D） reconstruction tomographies of the implantation study for repairing calvarium defects of rabbits demonstrated that the calvarium defects were almost completely filled by the osteotylus in PL/Sc-CO2 method group at 12 week post-surgery, while there was little callus formation in PL method group and untreated control group. These results indicate that the g-BG/PLGA scaffolds prepared by the PL/Sc-CO2 methods exhibit rapid mineralization and osteoconductivity and are the optimal composites for bone repair.