The present paper analyzes common mistakes in exemplification in the writing part of Band 4 College English Test.It discusses pertinence,appropriateness,typicality,logic and novelty of exemplification instead of dwelling on mistakes in spelling,wording and grammar,and offers some practical strategies of exemplification.

BACKGROUND: The area of myocardial infarction is the determinative factor of acute myocardial infarction prognosis. Amelioration of blood transportation and replacement therapy can reduce infarction area. Bone marrow mesenchymal stem cells can differentiate into cardiovascular tissue and are easy to obtain. After cultured and expanded in vitro, they can become the ideal cells for cardiovascular replacement therapy.OBJECTIVE: To evaluate the therapeutic effect of intracoronary transplantation of bone marrow mesenchymal stem cells in the treatment of myocardial infarction. DESIGN: Self-control observation taking the patients as subjects.SETTING: Department of Cardiology, Department of Nuclear Medicine,Echocardiogram Room, Nanjing First Hospital Affiliated to Nanjing Medical University.PARTICIPANTS: Totally 20 patients with acute myocardial infarction who received the therapy of bone marrow mesenchymal stem cells transplantation in the Department of Cardiology, Nanjing First Hospital Affiliated to Nanjing Medical University during March 2003 to March 2004 were recurited. Informed consents were obtained from the patients, and the complete postoperative follow up was over 3 months. The patients include 15 male and 5 female, and they were aged (64±10) years.METHODS: All the patients underwent percutaneous coronary intervention (PCI) to treat infarction-related blood vessel. Autologous bone marrow was taken from the patients, then stem cells were extracted to be performed in vitro induction, differentiation and proliferation, and transplanted infarction-related blood vessel through coronary artery at the mean number of (21.7±30.14)× 107 within 2 weeks. Before and 3 months after transplantation of stem cells, patients underwent gated dual-isotopic myocardial perfusion/metabolic imaging (18-fluoro-2-deoxy-glucose, 18F-FDG) examination. Survived and necrotic myocardia were predicted and infarction area was obtained. At the same time, wall motion and heart function index were evaluated with ultrasound cardiography (UCG)examination, and they were re-checked 3 months after operation to evaluate the amelioration of wall motion and heart function index. A 5-point scale was used in the evaluation of gated dual-isotopic myocardial perfusion/metabolic imaging (18F-FDG) examination: point 0: normal, 1: sparse, 2:obviously sparse, 3: defected. Evaluative standard of UCG: point 1: normal,2: reduced, 3: obviously reduced, 4: no ventricular wall motion or paradoxical motion; Wall motion with 2 points or more than 2 points suggests it is improved.MAIN OUTCOME MEASURES: ① Results of gated dual-isotopic myocardial perfusion/ metabolic imaging (18F-FDG-SPECT); ②Infarctionrelated myocardial segment score and heart function index before and after stem cell transplantation of patients in ECG follow-up observation.RESULTS: All the 20 patients participated in the result analysis.Results of gated dual-isotopic myocardial perrusion/metabolic imaging (18F-FDG-SPECT): The myocardial perfusion defect area of 20 patients was significantly reduced after therapy than before therapy [(33±15)%,-(44±18)% ,P ＜ 0.05]; Metabolie defect area was significantly reduced after therapy than before therapy [(33±17)%, (43±21)% ,P ＜ 0.05];Before therapy, there were 199 segments, in which blood flow reperfusion was matched to glycometabolism defect, and they were determined as necrotic myocardium. After therapy, blood flow perfusion metabolism was improved in 79 segments, but blood flow perfusion and glycometabolism were not improved significantly in 120 segments (P ＜ 0.05). Results of UCG: ejection fraction of patients was significantly larger after therapy than before therapy [(53±8)%, (42±7)% ,P ＜ 0.05].CONCLUSION: Intracoronary transplantation of human bone marrow mesenchymal stem cells for treating myocardial infarction is simple to operate. After therapy, the infarction area is obviously reduced, myocardial blood flow perfusion and metabolism of necrotic area improve, myocardial segments without survival determined before operation reduce sigrificantly and the heart function of patients improve.

OBJECTIVETo investigate the possible biological function and mechanism of miR-143 in the metastasis of human nasopharyngeal carcinoma (NPC).

METHODSUsing bioinformatics to predict the target gene of miR-143, the 3'UTR and mutant 3'UTR of GLI3 gene was cloned into psiCHECK-2 vector. Dual-luciferase reporter gene assay was employed to examine the repression of the GLI3 gene. miR-143 and GLI3 expression levels in 5-8F cells transfected with miR-143 mimics, inhibitor, or siGLI3 were examined, and the changes in the cell migration ability was assessed by Transwell invasion assay.

RESULTSBioinformatics prediction indicated the Hh pathway transcription gene GLI3 as a target gene of miR-143, and dual-luciferase reporter assay showed that miR-143 directly combined with the 3'UTR of GLI3. qRT-PCR and Western blotting demonstrated that the expression of miR-143 in 5-8F cells was negatively correlated to GLI3 and suppressed the migration of 5-8F cells.

CONCLUSIONMiR-143 can inhibit the invasion of NPC cells by negative regulation of GLI3 gene, which sheds light on the role of miR-143 and Hh pathway in NPC.

Carcinoma ; Cell Line, Tumor ; Cell Movement ; genetics ; Cell Proliferation ; Gene Expression Regulation, Neoplastic ; Genes, Reporter ; Humans ; Kruppel-Like Transcription Factors ; genetics ; MicroRNAs ; genetics ; Nasopharyngeal Neoplasms ; genetics ; pathology ; Nerve Tissue Proteins ; genetics ; Zinc Finger Protein Gli3

OBJECTIVETo detect miR-143 expression in human nasopharyngeal carcinoma (NPC) cell lines and explore the role of miR-143 in regulating the adhesion ability of NPC cells.

METHODSFluorescence quantitative RT-PCR was used to detect miR-143 expression levels in 5 NPC cell lines (CEN1, CNE2, HONE1, 5-8F, and 6-10B) and an immortalized human nasopharyngeal epithelial cell line (NP69). The retrovirus plasmid pMSCV-puro-miR-143 was constructed and the packaged retroviruses pMSCV-puro and pMSCV-puro-miR-143 were infected in 5-8F cells to establish a cell line with stable miR-143 overexpression, whose adhesion ability was tested with adhesion assay.

RESULTSThe expression of miR-143 was down- regulated in the NPC cell lines, and the highly metastatic NPC cell line 5-8F had a expression of only 3.0% of the control level, as compared with the level of 63.59% in the tumorigenic but nonmetastatic NPC cell line 6-10B. The transfected 5-8F cells showed a 1080-fold increase of miR-143 expression (P<0.05) with a significantly lowered adhesion ability.

CONCLUSIONmiR-143 plays a role in regulating the invasiveness and metastasis of NPC, and overexpression of miR-143 causes a significant reduction of the adhesion ability of the highly metastatic NPC cell line 5-8F.

Carcinoma ; Cell Adhesion ; Cell Line, Tumor ; Cell Movement ; Humans ; MicroRNAs ; metabolism ; Nasopharyngeal Neoplasms ; metabolism ; pathology