Objective To study the role of microRNA(miR)-483-3p in reducing myocardial fibrosis in rats,and explore the relationship between its mechanism and autophagy.Methods A total of 24 male SD rats were randomly divided into sham operation group,model group,blank transfec-tion group and high expression group,with 6 rats in each group.The blank transfection group and the high-expression group were pretreated with a single injection of adeno-associated virus(AAV)-blank transfection and AAV-miR-483-3p(5×1011 vg)in the tail vein,respectively.In 14 d later,the sham group was injected with 2.5 ml/(kg·d)normal saline for 14 d,and rat model of myocardial fibrosis was established by 2 mg/ml isoproterenol[2.5 ml/(kg·d)]injection through tail vein for 14 consecutive days.Myocardial pathological damage,severity of myocardial fibrosis,and expression levels of collagen-Ⅰ,microtubule-associated protein light chain 3(LC3),autoph-agy-related protein 5(Atg5)and autophagy degradation substrate(P62)in cardiomyocytes were evaluated and measured.Results Compared with the sham operation group,the model group had obviously larger myocardial fibrosis area,higher positive expression of Collagen-Ⅰ,and increased protein levels of Atg5 and LC3-Ⅱ/LC3-Ⅰ,and decreased expression level of P62 protein(P＜0.05).The myocardial fibrosis area,positive expression of Collagen-Ⅰ,the expression levels of Atg5 and LC3-Ⅱ/LC3-Ⅰ protein[(13.64±1.51)％vs(27.47±1.55)％,(13.48±3.07)％vs(30.91±2.45)％,0.98±0.17 vs 1.24±0.28,0.66±0.05 vs 1.26±0.09,P＜0.05]were significant-ly decreased,and the expression level of P62 was notably increased(0.91±0.11 vs 0.74±0.06,P＜0.05)in the high expression group than the model group.Conclusion MiR-483-3p attenuates myocardial fibrosis in rats,and the mechanism may be related to the inhibition of cardiomyocyte autophagy.

Objective:To construct the postgraduate teaching case database of rotation in department of cardiology, and to explore its application effect.Methods:The postgraduate teaching case base of rotation in department of cardiology was constructed during April 2020 to December 2020. A total of 32 graduate students rotating in Department of Cardiology of Affiliated Hospital of Guilin Medical University from January 2021 to April 2021 were selected and randomly divided into two groups. The routine group adopted the traditional teaching method, and the research group applied the teaching case base on this basis, both for one month. The examination results, the changes of clinical practice ability before and after the teaching, and the satisfaction with the teaching mode were compared between the two groups. SPSS 22.0 was used for t test and chi-square test. Results:The final results of the theoretical examination and practical operation examination of the two groups were higher than those of the entrance examination ( P<0.05), and the results of the theoretical examination and practical operation examination of the research group were higher than those of the routine group ( P<0.05). The scores of clinical practice ability of inquiry, case analysis, diagnosis, treatment and follow-up in the two groups after teaching were higher than those before teaching ( P<0.05), and the scores of clinical practice ability in the research group after teaching were higher than those in the routine group ( P<0.05). The satisfaction scores on improving examination results, enhancing clinical practice ability, deepening professional understanding and enhancing professional confidence of the teaching mode of the research group were higher than those of the routine group ( P<0.05). Conclusion:The construction and application of postgraduate teaching case base of cardiology rotation can improve the examination results, enhance the clinical practice ability, and achieve the satisfaction of postgraduates.

Objective To explore the therapeutic effect of bicyclol(BIC)on rat model of myocardial fibrosis and its possible mechanism.Methods Twenty-four SPF male SD rats were randomly di-vided into sham group,model group,low-and high-dose groups,with 6 rats in each group.Except for the sham group,all other groups were injected with 5 mg/(kg·d)isoproterenol by tail vein to establish myocardial fibrosis model,and the low-and high-dose groups were administered by ga-vage with 100 and 200 mg/(kg·d)BIC,respectively for 14 consecutive days.HE staining and Masson staining were used respectively to observe the severity of myocardial injury and fibrosis.Western blot assay was employed to detect the protein expression of Collagen Ⅰ,Collagen Ⅲ,al-pha smooth muscle actin(α-SMA),methyltransferase-like protein 3(METTL3),α-ketoglutarate-dependent dioxygenase AlkB homolog 5(ALKBH5)and YTH domain family protein 1(YTHDF1)in rat myocardium.Results Compared with the sham group,myocardial cell necrosis and myocardial fibrosis were significantly more serious in the model group.Low-and high-dose BIC treatment reduced myocardial cell rupture and necrosis and myocardial fibrosis when com-pared with the model group.The expression levels of Collagen Ⅰ,Collagen Ⅲ,α-SMA,METTL3 and YTHDF1(P＜0.05)were significantly higher,and that of ALKBH5(0.58±0.02 vs 0.88±0.07,P＜0.05)was notably lower in the myocardial tissues of the model group than the sham group.While,both doses of BIC treatment significantly reversed above changes in protein levels(P＜0.05).Conclusion BIC can effectively alleviate myocardial structural damage and interstitial collagen deposition in rats with isoproterenol-induced myocardial fibrosis,and its mechanism may be related to m6A methylation modification.