0.05).Conclusion: For teeth with perforation in root canal therapy,the Propex,Raypex 5 and Root ZX electronic apex locators can detect the perforation with high accuracy.

Resident standardization training is a major part of education of medical students after graduation , and is extremely important for high-level physician training and raising the quality of medical treatment. We trained the residents comprehensively according to the characteristics of echocardiography in terms of theoretical knowledge, clinical manipulative skills, clinical thinking ability, scientific research ability and communication and team cooperation ability, and carried out the relative examination according to the training. On the basis of practice, we explored the establishment of a standardized training mode and evaluation system suitable for echocardiography resident doctors in China.

Aim To explore the anti-apoptotic function of cardiac progenitor cells(CPCs)-derived exosome in vitro.Method CPCs were isolated from mouse heart using Magnetic Cell Sorting(MACS)system.Flow Cy-tometry(FC)determine the purity of stem cell surface antigen-1 positive(Sca-1 +)CPCs.Exosome was puri-fied from conditional medium,and confirmed by West-ern blot using CD63 as a marker,Nanoparticle Traffic-king Analysis(NTA)was used to detect the diameters and concentration of exosome.Then the cells were di-vided into control groups and CPC-exosome pre-protec-tion groups.H2 O2 was added into H9c2 cells to induce oxidative stress.Western blot was adopted to determine the expression of cleaved caspase-3.Results ① Im-munofluorescence showed that CPCs isolated by MACS were positively expressing Sca-1 protein;FC analysis showed that typical purity of Sca-1 +CPCs from the first
preparations was more than 95%.② WB demonstrated that CD63 of exosome isolated from CCMwas positively expressed,and NTA results showed that the diameters of exosome were (82.33 ±3.06)nm(n =3).Micro-scope detected PKH-26 labeled exosome appeared in the cytoplasma of H9c2 cells.③ Western blot showed the CPC-exosome pre-protection groups significantly down-regulated the levels of cleaved caspase-3 com-pared to the control groups(P <0.05).Conclusion CPC can secrete exosome which carries many important cargos,which can effectively gather in H9c2 cells. CPC-exosome can protect H9c2 cells from the oxidative stress induced by H2 O2 .Our results highlight a new perspective strategy for cardiac disease.

AIM: To screen the cytotoxicity of degradable calcium metaphosphate (dCMP) compared with hydroxyapatite (HA). The proliferation and differentiation abilities of human marrow mesenchymal stem cells (MSC) were used to exhibit the cytotoxicity. METHODS: The cell morphology of MSC was analysed after direct contact with dCMP at different time points by scanning electron microscopy analysis. The degradation products of dCMP and HA were analysed with inductively coupled plasma torch and ion chromatography. The cytotoxic effect of degradation products of dCMP was evaluated by FACS, quantitative assay of ALP and ARS, respectively. RESULTS: dCMP enhanced the proliferation of MSC, but didn't interfere the osteogenic differentiation process of MSC and its mineralization. HA inhibited the proliferation of MSC and the mineralization of osteogenic differentiated MSC, while it did not interfere the osteogenic differentiation process of MSC. CONCLUSION: dCMP had a better cytocompatibility with MSC than HA, which might allow for its use as skeleton scaffolds.

[ ABSTRACT] AIM:To investigate the role of encapsulated protein transfected into human bone marrow mesen-chymal stem cells ( hBMSCs) by polyethyleneimine ( PEI) , and to optimize the best mole ratio of PEI-proteins.METH-ODS:6 groups of DNase I-PEI complexes were constructed and the best mole ratio was explored by laser scattering analy-sis.The appearance of complexes was presented under transmission electron microscope.Meanwhile, 4 groups of construc-ted GFP-PEI complexes were utilized to transfect into the hBMSCs, which were isolated and expand in vitro.The fluores-cence intensity of transfected cells was observed under confocal microscope.In addition, the cytotoxicity of the complexes on the cell proliferation was detected by MTT assay.The activity of the intracellular proteins was testified by aβ-galactosi-dase staining experiment.RESULTS:When the mole ratio of PEI and protein was adjusted to 4∶1, the complex transfec-tion efficiency was the best, and β-galactosidase color test turned blue.CONCLUSION:PEI has the character of encap-sulating various proteins to nano-complexes.The proteins transfected into bone marrow mesenchymal stem cells are con-firmed to have functional activity.As a protein carrier, PEI is of high efficiency and low toxicity, thus providing a new way for stem cell reprogramming.

Objective To explore the application of optical coherence tomography in vascular tissue engineering culture by dynamic monitoring its changes.Methods Human umbilical artery smooth muscle cells were isolated and culture by tissue block method.After passage culture and cell surface markers evaluation, smooth muscle cells were seeded onto polyglycolic acid scaffold and placed into the bioreactor based on Luo-Ye pump with pulsatile stress for three-dimensional culture.At 1、4、 7 、10、14、17、21 days in culture, the image data was obtained by optical coherence tomography technology.The ability of imaging TEBV via OCT was analyzed combined with histopathological observation.Results As the incubation time extended,OCT clearly showed PGA gradual degradation, decreased composite scaffold thickness and the wall structure from loose to tight.At 21 days in culture, the vessel mimics had smooth surface with extracellular matrix evenly distributed and achieved complete reconstruction in the PGA scaffold.Combining with histopathological staining, the blood vessel mimics were similar to natural blood vessels.OCT measured TEBV thickness compared with histopathological measurement had good correlation (r =0.922,P ＜ 0.05).Conclusion Optical coherence tomography could clearly image microstructures of tissue engineered blood vessels cultured in three-dimensional culture system based on Luo-Ye pump, delineate the reconstruction of TEBV-like tissue in the bioreactor and provide as a dynamic and convenient monitoring tool in vascular tissue engineering.

Objective To investigate the effect of Xing-Zhi-Yi-Nao (XZYN) particles on the expressions of Nogo and OMgp proteins in brain of rats after acute carbon monoxide (CO) poisoning.Methods A total of 120 Sprague-Dawley rats were randomly divided into normal group,CO poisoning group and XZYN particles treatment group (40 rats in each group).The rats in CO poisoning group and treatment group of acute CO poisoning were established by using an animal chamber,and then received hyperbaric oxygen therapy.Meanwhile,rats in treatment group were further given additional XZYN particles twice a day by gavage.At 1 day,1 week,1 month and 2 months after CO poisoning,the neurobehavioral score of rats was evaluated by a Morris water maze test and a shuttle box test,and the expressions of neurite outgrowth inhibitor (Nogo) and oligodendrocyte-myelin glycoprotein (OMgp) were investigated in rat brain tissue by immunohistochemistry staining and western blotting assay,respectively.Results Compared with those in normal control group((11.6±8.4)s,(41.8±4.4)%,(16.1±2.3)s,and (1.2±0.2)s),the escape latency in CO group was significantly prolonged ((14.1±6.1)s),and the T1/ T total was obviously decreased (23.6±2.4) %,the escape time ((26.3±3.8)s),the active escape latency ((2.3±0.3)s) were notably extended at 1 d (P<0.05).The cognitive dysfunction caused by CO poisoning was more obvious in the later stage of poisoning (from 1 week to 2 months,P<0.05).Compared with those in CO group,the escape latency was significantly shortened (from (3.5±0.6)s to (3.1±0.5)s),the T1/ T total was gradually increased (from (29.7±3.2)% to (36.7±3.2)%),the escape time (from (39.7±5.4)s to (18.1±2.0)s) and the active escape latency were obviously decreased (from (4.3±0.4)s to (2.1±0.2)s) in the later stage (>1 week) in Xing-Zhi-Yi-Nao treatment group (P<0.05).The expressions of Nogo and Omgp proteins in brain tissue in CO poisoning group were gradually increased as time went by.The increased expressions of Nogo and Omgp proteins were still observed at 1 month after CO poisoning.By contrast,XZYN particles could significantly improve cognitive function,reduce the expression of Nogo protein,and there was statistical difference compared with the poisoning group (P<0.05).However,the level of Omgp protein in XZYN treatment group was slightly lower than that in CO poisoning group,but there was no difference between the two groups (P>0.05).Conclusion The expression of Nogo and Omgp proteins may be associated with brain injury and demyelination in rats induced by CO poisoning.XZYN particles can down-regulate the expression of Nogo,and pave a way for the treatment of acute brain damage and delayed encephalopathy after CO poisoning.

Objective To investigate right ventricular(RV) dyssynchrony in patients with pulmonary hypertension(PH)by strain imaging.Methods Sixty PH patients were divided into three groups according to the pulmonary artery systolic pressure(PASP),20 healthy volunteers served as control group.RV structures parameters included RV end-diastolic area(RVEDA),end-systolic area(RVESA),the ratio of RV diameter and LV diameter(RVTD/LVTD).RV function parameters included RV fractional area change (RVFAC)and Tei index.RV strain parameters included the maxmal differences of the peak systolic strain(Max-ΔPST)and the maxmal differences of the time to peak systolic strain(Max-ΔT_(Q-S))of each segment.Results Compared with control group, Max-ΔT_(Q-S) and Max-ΔPST of PH groups were significantly larger (P<0.01).Max-ΔT_(Q-S) had strong correlations with PASP and RV structure and function parameters(P<0.01).Max-ΔPST had good correlations with PASP and Tei-index(P<0.05,P<0.01).Conclusions PH patients exhibit right ventricular dyssynchrony which correlates with right ventricular function and structure parameters.Right ventricular dyssynchrony parameters could evaluate right ventricular function in PH patients early by strain imaging.

Aim To investigate whether human umbili-cal cord mesenchymal stem cells(hUC-MSCs)exposed to inflammatory conditions could release large amounts of exosomes to induce regulatory T cells(Treg).Meth-ods hUC-MSCs were isolated by enzyme digestion method.(In vitro)interferonγ(IFN-γ)was added in-to hUC-MSCs to mimic inflammatory microenviron-ments,then exosomes were extracted from the superna-tant of normal conditional medium or IFN-γpretreated hUC-MSCs.Both sources of exosomes,Nor-hUC-exo and IFN-γ-stimulated hUC-exo, were identified by Nanoparticle Trafficking Analysis (NTA )and Western blot for the exosome-enriched protein CD63 .Next,hu-man peripheral blood mononuclear cells (PBMCs ) stimulated with PHA were respectively co-cultured with hUC-MSCs,IFN-γ-pretreated-hUC-MSCs,hUC-MSCs exosomes or IFN-γ-stimulated-hUC-MSCs exosomes for 5 days to assess the exosomes-T cells communication. The proliferation rate of PBMCs and frequency of CD4 +/CD25 +/Foxp3 + Treg were measured by flow cytometry.Results The isolated cells from human um-bilical cord tissue,which were positive for CD73, CD44,CD29,CD90 and HLA-ABC,but were nega-tive for CD31 and CD34,were mesenchymal stem cells indeed.After IFN-γtreatment,hUC-MSCs secreted nu-merous exosomes(P<0.05 ).Morerover,there was a significantly higher level of CD63 ,but no difference in diameter between Nor-hUC-exo and IFN-γ-stimulated hUC-exo.IFN-γ-stimulated hUC-exo had a superior a-bility compared with Nor-hUC-exo to suppress the pro-liferation of PHA stimulated PBMCs due to their upreg-ulation of the percentage of Treg (1 1.53 ±0.88% vs 6.60 ±0.56%,P <0.01 ).Conclusion hUC-MSCs could promote the expression of Treg to modulate im-munosuppression through exosomes,especially for IFN-γ-licenced exosomes,which might carry much immu-notherapeutic potential.

Human acute premyeloid leukemia cell cDNA expression library was constructed to screen acute premyeloid leukemia tumor antigen. Total RNA and purified mRNA were extracted from human premyeloid cell line NB4. First and second strands of cDNA were synthesized by reverse transcription. After blunting, the cDNA fragments were ligated with EcoR I adapters. Then the cDNAs were digested with Xho I, and less than 400 bp cDNA fragment was removed by Sephacryl-S400 spin column, the remaining were ligated with lambdaZAP vector. The recombinants were packaged in vitro, and a small portion of packaged phage was used to infect E. coli XL1-Blue-MRF' for titration. The recombinants were examined by color selection. In order to evaluate the size of cDNA inserts and the diversity of library, the pBK-CMV phagemid was excised from the ZAP express vector by using ExAssist helper phage with XLOLR strain, and then the pBK-CMV phagemid was digested by Xho I and EcoR I. The results showed that the NB4 cell line cDNA library consisting of 1.65 x 10(6) recombinant bacteriophages was constructed with the recombinant ratio of 99.6%. The average length of the recombinant exogenous inserts was about 1.7 kb. It was concluded that the constructed cDNA library are deserved to screen target clones.
Bacteriophages/genetics ; DNA, Complementary/*biosynthesis ; *DNA, Neoplasm/biosynthesis ; DNA, Recombinant/biosynthesis ; *Gene Library ; Genetic Vectors ; Leukemia, Promyelocytic, Acute/*genetics ; Leukemia, Promyelocytic, Acute/metabolism ; Leukemia, Promyelocytic, Acute/pathology ; RNA-Directed DNA Polymerase/metabolism ; Transcription, Genetic/genetics