Effect of printing orientation on physical and mechanical properties of 3D printing prosthodontic base resin materials / 北京大学学报(医学版)

Objective:To analyze the influence of forming direction on the surface characteristics,elastic modulus,bending strength and fracture toughness of printed parts and the relationship between forming direction and force direction,and to provide scientific basis and guidance for the clinical applica-tion of oral denture base resin materials.Methods:The 3D printing technology was used to print denture base resin samples.The shape and size of the samples referred to the current standard for testing conven-tional denture base materials.The samples used for physical performance testing were cylindrical(with a diameter of 15 mm and a thickness of 1 mm)and printed at different angles along the Z axis(0°,45°,90°).Scanning electron microscope was used to observe the microscopic topography of the different sam-ples.The color stability of different samples was observed by color stabilizer.The surface roughness of the samples was analyzed by using surface roughness tester.The Vickers hardness was measured to ana-lyze the hardness of the samples.The samples used for mechanical performance testing were rectangular(elastic modulus and bending strength:A length of 64 mm,a width of 10 mm,and a height of 3.3 mm;fracture toughness:A length of 39 mm,a width of 8 mm,and a height of 4 mm),divided into two groups:W group and H group.The W group was printed from the bottom up along the Z axis with the length × width as the bottom surface parallel to the X,Y axis plane,while the H group printed from the bottom up along the Z axis with the length × height as the bottom surface parallel to the X,Y axis plane.The forming angles of both groups were equally divided into 0°,45°,and 90°.The elastic modulus,bending strength and fracture toughness of different samples were studied through universal mechanical testing machine.SPSS 22.0 software was used for statistical analysis.Results:The microscopic topogra-phy and roughness of different samples were closely related to the printing direction,with significant differences between the 0°,45°,and 90° specimens.The 0° specimens had the smoothest surface(roughness＜1 μm).The surface of the 45 ° specimen was the roughest(roughness＞3 μm).The microhardness of the 0° sample was the best[(196.13±0.20)MPa],with a significant difference com-pared with the 90° sample[(186.62±4.81)MPa,P＜0.05].The mechanical properties of different samples were also closely related to the printing direction.The elastic modulus,bending strength,and fracture toughness of the 45° samples in the W group were the highest compared with the other groups.The results of elastic modulus showed that in the H group,the 45° specimens had the highest elastic mo-dulus,which was significantly different from the 0° and 90° specimens(P＜0.05).The elastic modulus of 0° and 45° specimens in the W group were higher than those in 90° specimens(P＜0.05).The bending strength results showed that there was no significant difference between the specimens from dif-ferent angles in the H group.The bending strength of the 90° specimens in the W group was the smallest,and there was a significant difference between 90° and the 0° and 45° specimens(P＜0.05);And the bendind strength of the 0° and 45° specimens in the W group was significantly higher than that of the 0° and 45° specimens in the H group(P＜0.05).The fracture toughness results showed that the fracture toughness of the H group specimens was lower than 1.9 MPa m1/2,which was specified in the denture base standard.The 45° samples in the W group were the highest,with significant differences compared with the 0° and 90° samples(P＜0.05).And the 90° samples of the W group specimens were lower than 1.9 MPa m1/2.And the fracture toughness of the 45° specimen in the W group was significantly higher than that of all the specimens in the H group(P＜0.05).Conclusion:The 0° samples had rela-tively better physical properties.The 45° samples had the best mechanical properties.But the fracture toughness of specimens(H group and 90° samples of W group)did not yet meet clinical requirements.That indicated that the characteristics of the 3D printing denture base resin were affected by the printing direction.Only when the performance of the printed samples in all directions met the minimum require-ments of the standard,they could be used in clinical practice.

Effects of nano-zirconium dioxide on osteogenic differentiation of ectomesenchymal stem cells in nasal mucosa / 中国组织工程研究

BACKGROUND:Nano-zirconium dioxide has good application potential in the field of bone tissue repair.Studying the effect of nano-zirconium dioxide on osteogenic differentiation will help to promote the clinical application of nano-zirconium dioxide in the treatment of bone defects. OBJECTIVE:To explore the effect of nano-zirconium dioxide on the osteogenic differentiation of ectomesenchymal stem cells in the nasal mucosa. METHODS:Ectomesenchymal stem cells derived from rat nasal mucosa were isolated and cultured,and the biotoxicity of nano-zirconium dioxide to the cells was detected by CCK-8 assay.The biosafety concentration was selected according to the cytotoxicity,and the cells were randomly divided into a control group,a nano-zirconium dioxide group,and a nano-hydroxyapatite group.Osteogenic differentiation of cells was directionally induced in each group.On day 7 of induced differentiation,alkaline phosphatase staining was performed.qRT-PCR and western blot assay were used to detect the expression of early osteogenic markers(Runx2 and Osx).On day 21 of induced differentiation,alizarin red staining was conducted.qRT-PCR and western blot assay were utilized to determine the expression levels of late osteogenic markers(OPN and OCN). RESULTS AND CONCLUSION:(1)The median lethal concentration of nano-zirconium dioxide on ectomesenchymal stem cells in nasal mucosa was 0.6 mg/mL.In the experiment,the mass concentration of 200 μg/mL was selected for intervention.Zirconium dioxide had no significant effect on the proliferation of the cells.(2)Compared with the control group,the alkaline phosphatase staining of the cells in the nano-zirconium dioxide group was more obvious and the level of cell mineralization was higher,but there was no significant difference compared with the nano-hydroxyapatite.(3)Compared with the control group,the expression of bone-related genes and proteins increased significantly,but there was no significant difference compared with nano-hydroxyapatite.(4)The results show that nano-zirconium dioxide has good biological safety and can promote the osteogenic differentiation of ectomesenchymal stem cells in the nasal mucosa.This promoting effect is equivalent to that of nano-hydroxyapatite.

Drug target discovery by magnetic nanoparticles coupled mass spectrometry / 药物分析学报

Drug target discovery is the basis of drug screening.It elucidates the cause of disease and the mechanism of drug action,which is the essential of drug innovation.Target discovery performed in biological sys-tems is complicated as proteins are in low abundance and endogenous compounds may interfere with drug binding.Therefore,methods to track drug-target interactions in biological matrices are urgently required.In this work,a Fe3O4 nanoparticle-based approach was developed for drug-target screening in biofluids.A known ligand-protein complex was selected as a principle-to-proof example to validate the feasibility.After incubation in cell lysates,ligand-modified Fe3O4 nanoparticles bound to the target protein and formed complexes that were separated from the lysates by a magnet for further analysis.The large surface-to-volume ratio of the nanoparticles provides more active sites for the modification of chemical drugs.It enhances the opportunity for ligand-protein interactions,which is beneficial for capturing target proteins,especially for those with low abundance.Additionally,a one-step magnetic separation simplifies the pre-processing of ligand-protein complexes,so it effectively reduces the endogenous interference.Therefore,the present nanoparticle-based approach has the potential to be used for drug target screening in biological systems.

miR-29a in Exosomes from Bone Marrow Mesenchymal Stem Cells Inhibit Fibrosis during Endometrial Repair of Intrauterine Adhesion

Background and Objectives@#Bone marrow mesenchymal stem cells (BMSCs) is an ideal source of stem cells in the treatment of intrauterine adhesion. Exosomes are a type of membrane vesicle and the diameter is 30∼100 nm. Exosomes can take their contents into the target cells, releasing and exerting their functions. In this study, we intend to study the role of human BMSC-derived exosomes (BMSC-Exo) in promoting endometrial damage repair in the treatment of IUA. @*Methods@#We used the magnetic bead affinity method to extract BMSC-Exo and analyzed its biological character. Then we co-cultured the BMSCs-Exo with endometrial cells to detect its effect. We injected BMSCs-Exo into the IUA mouse model. We over-expressed miR-29a in BMSCs-Exo by transient transfection, then used RT-PCR to analyze the expression of the related genes. @*Results@#BMSCs-Exo expressed exosome-specific proteins CD9, CD63, and CD81. BMSCs-Exo could bring the contents into the target cells. BMSCs-Exo can promote endometrial repair in vitro or in vivo. BMSCs-Exo overexpressing miR-29a can reduce αSMA, Collagen I, SMAD2, and SMAD3. @*Conclusions@#In this study, we successfully isolated BMSCs-Exo and proved its character and biological activity. BMSCs-Exo can promote cell proliferation and cell migration in vitro and can repair damaged endometrium in the IUA model. The presence of miR-29a in BMSCs-Exo may be an important factor in its resistance to fibrosis during endometrial repair of IUA. This study provides new ideas for the treatment of patients with IUA and has important clinical research significance.

Correlation between K-ras gene mutation and clinicopathological characteristics and prognosis of colorectal cancer patients with different primary sites / 肿瘤研究与临床

Objective To analyze the correlation between K-ras gene mutation and clinicopathological characteristics and prognosis of colorectal cancer patients with different primary sites.Methods The clinical and pathological records of 69 patients who were pathologically confirmed as colorectal cancer and tested K-ras gene status at Wuxi People's Hospital Affiliated to Nanjing Medical University between May 2007 and August 2017 were adopted.The correlation between clinicopathological characteristics and prognosis of colorectal cancer patients with different primary sites and K-ras gene mutation status were retrospectively analyzed.And the patients were visited to adopt the prognosis data and perform the Kaplan-Meier survival analysis.Results The K-ras mutation rate was 50.7％(35/69),including 40.0％(12/30)in left-side colon cancer,73.3％(11/15)in right-side colon cancer and 50.0％(12/24)in rectal cancer.The mutation rate of K-ras gene in patients ≥ 60 years old [61.5％(24/39)vs.36.7％(11/30),χ2= 4.197,P = 0.041] or serum CA19-9 raising up abnormally was conspicuously high [65.6％(19/29)vs.37.5％(15/40),χ 2= 5.486,P =0.019].Other clinicopathological characteristics,such as gender,lesion location,histological classification,TNM stage,serum CEA expression,clinical features had no correlation with K-ras gene mutation status(all P＞ 0.05).And no relationship was found between prognosis and overall survival of colorectal cancer patients with different primary sites and K-ras gene mutation status(χ 2= 0.001,P = 0.997; χ 2= 0.583,P =0.445).In general,the 5-year survival rate of left-side colon cancer patients was highest(76.9％),followed by rectal cancer(69.7％),and right-side colon cancer was lowest(31.3％).The primary site of colorectal cancer was related to the overall survival of patients(χ2=11.004,P =0.004).Conclusions K-ras gene mutation in colorectal cancer is closely related to age and serum CA19-9 levels of the patients.The prognosis of left-side colon cancer is best,rectal cancer second,and right-side colon cancer poorest.Whether K-ras gene mutation is the prognostic factor of colorectal cancer is not clear.Testing the K-ras gene status and serum tumor index expression,distinguish the primary site and age group will provide the theory basis and promote the clinical targeted therapy and improve the survival of colorectal cancer patients.