LncRNA TUG1 competitively binds to miR-340 to accelerate myocardial ischemia-reperfusion injury.

The aberrant expression of long noncoding RNA (lncRNA) taurine-upregulated gene 1 (TUG1) has been previously associated with myocardial ischemia-reperfusion injury (MIRI), but the underlying molecular mechanisms remain elusive. The current study aimed to clarify the functional role of TUG1/microRNA (miR)-340/histone deacetylase 4 (HDAC4)/ß-catenin/glucose transporter type 1 (GLUT1) axes in MIRI. The database-based analyses performed predicted the downstream factors of lncRNA TUG1. In the MIRI mouse models and hypoxia/reoxygenation (H/R)-induced cardiomyocyte models, the expression of TUG1/miR-340/HDAC4/ß-catenin/GLUT1 was manipulated to examine their effects on the infarction area, cardiomyocyte viability and apoptosis employing the Evans blue/TTC double staining, CCK-8 and TUNEL assays. Furthermore, the dual luciferase reporter and RIP assays verified the binding affinity of miR-340 to TUG1 and HDAC4. Subsequently, a negative correlation between miR-340 and TUG1 or HDAC4 expression was identified in myocardial tissues of MIRI mice and H/R-induced cardiomyocyte models, along with a positive correlation between TUG1 and HDAC4. Additionally, it was established that TUG1 bound to miR-340, and miR-340 targeted HDAC4. TUG1 upregulated HDAC4 expression, thereby promoting MIRI in the mouse models. HDAC4 was proven to repress the expression of ß-catenin and its target gene GLUT1. Moreover, the in vivo experiments validated that the inhibition of TUG1/miR-340/HDAC4/ß-catenin/GLUT1 axes alleviated MIRI in mice. Collectively, the current study uncovered the role of TUG1/miR-340/HDAC4/ß-catenin/GLUT1 axes in MIRI mouse models and H/R-induced cardiomyocyte models which may be a potential therapeutic target for MIRI treatment.

Analysis of the Learning Curve in Mitral Valve Replacement Through the Right Anterolateral Minithoracotomy Approach: A Surgeon's Experience with the First 100 Patients.

BACKGROUND: To apply the cumulative sum (CUSUM) failure analysis to assess the performance of a single surgeon during mitral valve replacement via the right anterolateral minithoracotomy (RAMT) approach and to analyse the learning curve for the procedure. METHODS: A total of 100 mitral valve replacements were performed using the RAMT approach from June 2011 to April 2013 by a single surgeon with no prior experience of this technique. Patients were divided into five blocks according to the operation date. The perioperative data were collected prospectively and analysed using descriptive statistics and CUSUM failure analysis. RESULTS: No significant differences in the background factors among the five periods were observed, except for a small increase in patient age from periods 1 to 5 (p=0.004). The surgeon's performance improved with time; a decrease in the cross-clamp time, operative time, and blood loss was observed (p<0.001). However, no significant difference in the number of failed cases was observed among the periods. All failure cases were evaluated by the CUSUM failure analysis and the CUSUM curve reflected a learning curve associated with this new procedure. The surgeon crossed the lower 80% boundary after about 33 operations, which indicates that better results can be obtained after this point. CONCLUSIONS: Minimally invasive mitral valve surgery using the RAMT approach can be performed by a new surgeon. Furthermore, CUSUM curve analysis is a simple statistical method to implement continuous individual performance monitoring.

Extended vertical transseptal approach versus transseptal approach for mitral valve operation.

BACKGROUND: Adequate exposure of the mitral valve is a critical factor of success for either replacement or repair of the mitral valve. In the present study, we evaluated the merits of the extended vertical transseptal approach in comparison with the transseptal approach for mitral valve operations. METHODS: A total of 72 consecutive patients operated on for mitral procedures were allocated to either group A (those operated on through an extended vertical transseptal approach [n = 38]) or group B (whose mitral valve exposure was achieved through a right atrium transseptal approach [n = 34]). The operation time, aortic cross-clamp time, first 24-hour drainage volume after the operation, and the rhythms pre- and postsurgery were compared between the 2 groups. RESULTS: The mean operation time and mean cross-clamp time in group A were longer than that in group B and the drainage volume was greater in the first 24 hours, but the differences were not statistically significant. There was no surgical reexploration for bleeding in either group. For the 13 patients who had normal sinus rhythm preoperatively in group A, 2 (15.4%) developed episodes of atrial fibrillation and 1 (7.7%) developed temporary sinus bradycardia requiring temporary pacing in the immediate and early postoperative period. In group B, 2(15.4%) of patients with normal sinus rhythm before surgery developed atrial fibrillation that continued until 1 week after surgery. CONCLUSION: The extended vertical transseptal approach not only affords excellent exposure of the mitral valve, but also is safe for maintaining sinus node function compared with the transseptal approach.