Objective To specifically extract and analyze nascent proteins synthesized by bone marrow mesenchymal stem cells(BMSCs)after transplantation into ischemic hearts using a technique employing mutant methionyl-tRNA synthetase(MetRSL247G)for nascent protein labeling,in order to explore the potential mechanisms of action in BMSCs post-transplantation.Methods Point mutation at position 274 of the MetRS gene in BMSCs was induced via lentiviral infection to enable azidonorleucine(ANL)-mediated labeling of nascent proteins in BMSCs.The labeling efficiency was verified by means of fluorescent non-canonical amino-acid tagging(FUNCAT).Thirty healthy female C57BL/6J mice(8-10 weeks old)were divided into control and experimental groups,with 15 mice in each group.The acute myocardial infarction model was constructed by ligating the left anterior descending coronary artery in experimental group,while control mice underwent only thoracotomy without coronary ligation.After modeling,both groups received intramyocardial injections of MetRSL247G-modified BMSCs(MetRSL247G-BMSCs)at 3 different sites in the peri-infarct ischemic region.Mice were intraperitoneally injected with ANL every 6 hours for 4 times on postoperative days 0,2,and 6(n=5 for each time point)respectively,euthanized 24 h after the last injection,and cardiac tissues were isolated.The newly synthesized and labeled proteins produced by BMSCs after transplantation into the myocardium of experimental and control groups were collected,using an enrichment technique for ANL-tagged proteins and liquid chromatography-tandem mass spectrometry(LC-MS)analysis.Gene ontology(GO)analysis,Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis,protein-protein interaction(PPI)analysis,and heatmap visualization analysis were performed to identify differentially expressed proteins at the 3 time points and screen key pathways and genes.Results Under fluorescence microscopy,the MetRSL247G lentivirus-infected BMSCs were observed to be labelled with mCherry signals,confirming the successful construction of the MetRSL247G-BMSCs cell line.Green fluorescent signals were detected only in nascent proteins in culture medium containing both MetRSL247G-BMSCs and ANL,validating the sensitivity and specificity of the labeling method.GO analysis revealed that differentially expressed proteins were primarily involved in basic cellular biological processes such as extracellular exosome formation,extracellular matrix organization,and focal adhesion.KEGG and PPI analyses indicated that the differential proteins were mainly involved in complement and coagulation cascade pathway,actin cytoskeleton regulation pathway,and apoptosis pathway.Heatmap analysis showed significantly upregulated expression of anti-apoptosis and cell adhesion-related factors in experimental group on day 1(P＜0.05),upregulated anti-apoptotic factors,pro-apoptotic factors,and cell adhesion-related factors on day 3(P＜0.05),and upregulated anti-apoptotic factors,cell differentiation-related factors,and cell adhesion-related factors on day 7(P＜0.05)compared with control group.Expression of apoptosis-inducing factor 1 was significantly downregulated on days 1 and 7(P＜0.05).On day 3,most differentially expressed proteins,including anti-apoptosis factors(Protein S100-A11,Clusterin,Gelsolin),pro-apoptosis factor(Cathepsin B),cell differentiation-related factor(Transgelin-2),and cell adhesion-related factors(Cofilin-1,Periostin,Fibronectin)were significantly upregulated(P＜0.05).Conclusions The MetRSL247G mutation enables BMSCs to incorporate ANL and synthesize labeled proteins,confirming the feasibility of this nascent protein labeling technique.Nascent proteins of BMSCs in ischemic myocardium primarily contribute to extracellular exosome secretion and extracellular matrix organization.BMSCs may adapt to and respond to ischemic and hypoxic environments by influencing complement and coagulation cascades,activating inflammatory factors,regulating actin cytoskeleton structure,and modulating apoptosis,thereby maintaining the survival of BMSCs.

【Objective】To explore the feasibility and simplicity of intelligent automatic registration ultrasound-CT/ MR fusion imaging based on liver surface in localization of focal liver lesions. 【Methods】 Thirty patients with detected focal liver lesions by contrast- enhanced CT or MR were enrolled for ultrasound- CT/MR fusion imaging using the PercuNav fusion imaging system in PHILPS EPIQ7. Both intelligent automatic registration ultrasound- CT/MR fusion imaging based on liver surface（intelligent method）and the conventional internal plane method（manual method）were used for ultrasound-CT/MR fusion imaging. The success rate of registration，the initial registration error and the times of fine-tuning were compared between these two methods.【Results】In all 30 patients，the success rates of registration were both 96.67%（29/30）using intelligent method and manual method. There was no significant difference between these two methods when compared the initial registration error and the times of fine- tuning （P>0.05）. According to the further stratified analysis，in 10 lesions in the left liver，the initial registration error of the manual method was less than that of intelligent method，the difference was statistically significant（P=0.00）. Although the times of fine-tuning of the manual method was less than that of intelligent method，there was no statistically significant difference（P=0.09）；In 20 lesions in the right liver，the initial registration error and the times of fine-tuning of the intelligent method were superior to those of the manual method. The differences were statistically significant （P<0.05）. 【Conclusion】 Intelligent automatic registration ultrasound- CT/MR fusion imaging based on liver surface is a feasible method with high success rate for ultrasound-CT/MR fusion imaging. Compared with the conventional internal plane method，the fusion imaging process is more simple and efficient for the lesions in right liver. It helps to reduce experience dependence of fusion imaging for the operators.

[Objective]To investigate the effect of human umbilical cord mesenchymal stem cells on infected state of human alve?olar type Ⅱ epithelial cells.[Methods]Human alveolar type Ⅱ epithelial cells A549(1×105/mL)2 mL and PA(3×104 CFU/mL)2 mL has grown after 6 hours,add hUCMSC(1 × 106/mL)2 mL as the experimental group,add equal amounts of phosphate buffer (PBS)for infection,A549 and PBS and the medium has grown as the control group. A549 cells morphological changes between the compared groups(Transmission electron microscope,TEM),A549 cell viability(new CCK-8 cell proliferation assay Kit),A549 cells apoptosis(Annexin V-FITC/PI double staining flow cytometry)and the expression of A549 pulmonary surfactant A(SP-A) (Western blot).[Results]Transmission electron microscope cell morphology observation displayed ,infection group A549 cell dam?aged obviously,cell quality appeared empty bubble degeneration,chromatin height agglutination,visible apoptosis bodies;experi?ment group cell package film structure full,nuclear film full,nucleolus obviously,nuclear chromatin electronic density low,chroma? tin uniform,no apoptotic bodies;control group A549 cell structure full,membrane surface micro-fluff rich,nuclear film full,nucle?ar week clearance structure normal,chromatin uniform;infection group and control group compared,Infection group A549 cell sur?vival significantly reduced[(70.35±2.89)% and(97.37±2.07)%,n=3,P<0.01],apoptosis rate significantly increased[(8.63%± 0.16)%and(2.55±0.11)%,n=3,P<0.01],In the infected group,PA could damage A549 cells and decrease the amount of SP-A ex?pression(n=5,P<0.05). In the experiment group,the protective effect of hUCMSC on the A549 cells after infection may increase the expression of SP-A(n=5,P<0.05);[Conclusions]HUCMSC inhibits the infection of A549 cells apoptosis and protection of A549 cells secrete SP-A.