ObjectiveTo investigate the feasibility of magnamosis rings designed based on magnetic compression technique in esophageal anastomosis reconstruction.MethodsAccording to the anatomical characteristics of esophagus in SD rats, the esophageal magnamosis rings were designed. SD rats were used as animal models (n=10, 5 males and 5 females) to complete the magnetic anastomosis reconstruction of the cervical esophagus using magnamosis rings, and the operation time, animal survival, postoperative complications, magnetic rings excretion time were recorded. Two weeks after operation, the rats were killed, and the esophageal anastomotic specimens were obtained. The blasting pressure of the anastomotic site was measured and the formation of the anastomotic site was observed with naked eyes.ResultsEsophageal magnamosis was successfully performed in 10 SD rats, and the median operation time was 11 (8-13) min. All rats survived without anastomotic leakage, anastomotic stenosis, or magnetic rings incarceration. The magnetic rings were discharged after 8 (5-10) days and the burst pressure was higher than 300 mm Hg. Visual observation showed that the anastomotic muscle healed well and the mucosa was smooth.ConclusionThe magnetic compression technique can be used for anastomosis reconstruction of esophagus, which has the advantages of simple operation and reliable anastomosis effect, and has clinical application prospect.
Objective To investigate the expression of miR-31a-5p in myocardial infarction (MI) mice and its potential mechanism. Methods A dataset was downloaded from the gene expression database, and miR-31a-5p and its predicted target gene hypoxia-inducible factor-1α (HIF-1α) were screened using bioinformatics methods. The MI model was established by ligating the left anterior descending branch of the coronary artery in C57BL/6J male mice which were randomly divided into sham and MI groups (n=6 in each group). The in vitro hypoxic cell model was induced by treatment of H9c2 cells with cobalt chloride (CoCl2) and divided into a control group, a model group, a NC group, a miR-31a-5p mimic group and a miR-31a-5p inhibitor group. The degree of myocardial tissue fibrosis was stained by Masson and analyzed. The expression levels of miR-31a-5p and HIF-1α mRNA in mouse myocardial tissues and H9c2 cells were detected by qRT-PCR. Western blotting was used to detect the expression levels of B-cell lymphoma 2 (Bcl-2), cleaved-caspase 3 apoptotic protein in mouse myocardial tissues and HIF-1α and apoptotic protein in H9c2 cells, respectively. The dual luciferase reporter gene assay was used to verify the targeting relationship between miR-31a-5p and HIF-1α. Results Masson staining showed significantly increased fibrosis in MI mice (P<0.000 1); miR-31a-5p, cleaved-caspase 3 were significantly elevated and Bcl-2 was decreased in MI mice and CoCl2 treated H9c2 (P<0.05). The results of dual luciferase reporter assay showed that the relative luciferase activity of miR-31a-5p mimic cotransfected with HIF-1α-3'-UTR WT plasmid was reduced (P<0.000 1); miR-31a-5p mimic decreased HIF-1α expression and increased apoptotic protein levels in CoCl2 induced H9c2 cells (both P<0.05), while miR-31a-5p exerted the opposite effect. Conclusion miR-31a-5p can aggravate apoptosis in myocardial ischemia by targeting HIF-1α.
Randomized controlled trials (RCTs) are often limited because of ethical or operational reasons. Quasi-experimental studies could be an alternative to RCTs to make causal inferences without randomization by controlling the confounding effects of the study. This paper introduced the general statistical analysis methods of quasi-experimental design through basic ideas, characteristics, limitations and applications in medicine, including difference-in-difference models, instrumental variables, regression discontinuity design, interrupted time series, and so on, and to provide references for future research.