Up-regulated novel-miR-17 promotes hypothermic reperfusion arrhythmias by negatively targeting Gja1 and mediating activation of the PKC/c-Jun signaling pathway.

BACKGROUND: Hypothermic ischemia-reperfusion arrhythmia is a common complication of cardiothoracic surgery under cardiopulmonary bypass, but few studies have focused on this type of arrhythmia. Our prior study discovered reduced myocardial Cx43 protein levels may be linked to hypothermic reperfusion arrhythmias. However, more detailed molecular mechanism research is required. METHOD: The microRNA and mRNA expression levels in myocardial tissues were detected by real-time quantitative PCR (RT-qPCR). Besides, the occurrence of hypothermic reperfusion arrhythmias and changes in myocardial electrical conduction were assessed by electrocardiography and ventricular epicardial activation mapping. Furthermore, bioinformatics analysis, applying antagonists of miRNA, western blotting, immunohistochemistry, a dual luciferase assay, and pearson correlation analysis were performed to investigate the underlying molecular mechanisms. RESULTS: The expression level of novel-miR-17 was up-regulated in hypothermic ischemia-reperfusion myocardial tissues. Inhibition of novel-miR-17 upregulation ameliorated cardiomyocyte edema, reduced apoptosis, increased myocardial electrical conduction velocity, and shortened the duration of reperfusion arrhythmias. Mechanistic studies showed that novel-miR-17 reduced the expression of Cx43 by directly targeting Gja1 while mediating the activation of the PKC/c-Jun signaling pathway. CONCLUSION: Up-regulated novel-miR-17 is a newly discovered pro-arrhythmic microRNA that may serve as a potential therapeutic target and biomarker for hypothermic reperfusion arrhythmias.

A BRAF mutation-associated gene risk model for predicting the prognosis of melanoma.

BRAF mutation plays an important role in the pathogenesis and progression of melanoma and is correlated to the prognosis of melanoma patients. However, fewer studies have attempted to develop a BRAF mutation-associated gene risk model for predicting the prognosis of melanoma. The current research explores BRAF mutation-related biological features in melanoma and establishes a prognostic signature. First, we identified three significantly enriched KEGG pathways (glycosphingolipid biosynthesis - ganglio series, ether lipid metabolism, and glycosaminoglycan biosynthesis - keratan sulfate) and corresponding genes in the BRAF mutant group by gene set enrichment analysis. We then developed a prognostic signature based on 7 BRAF-associated genes (PLA2G2D, FUT8, PLA2G4E, PLA2G5, PLA2G1B, B3GNT2, and ST3GAL5) and assessed its prediction accuracy using ROC curve analysis. Finally, the nomogram was established according to the prognostic signature and independent clinical characteristics to predict the survival of melanoma patients. Furthermore, we found higher proportions of naive B cells, plasma cells, CD8 T cells, CD4 memory-activated T cells, and regulatory T cells in the low-risk group. Whereas lower proportions of M0, M1, and M2 macrophages and resting NK cells were observed in the high-risk group. The analysis also showed a significantly higher expression of immune checkpoint molecules (PD-1, PD-L1, CTLA4, BTLA, CD28, CD80, CD86, HAVCR2, ICOS, LAG3, and TIGIT) in the low-risk group. Our results provide novel insights into the effect of BRAF mutation on melanoma growth and indicate a promising direction toward immunotherapy and precision medicine in melanoma patients.

Molecular chaperones HSP40, HSP70, STIP1, and HSP90 are involved in stabilization of Cx43.

To investigate the involvement of stress induced phosphoprotein 1 (STIP1), heat shock protein (HSP) 70, and HSP90 in ubiquitination of connexin 43 (Cx43) in rat H9c2 cardiomyocytes. Co-immunoprecipitation was used to detect protein-protein interactions and Cx43 ubiquitination. Immunofluorescence was used for protein co-localization. The protein binding, Cx43 protein expression, and Cx43 ubiquitination were reanalyzed in H9c2 cells with modified STIP1 and/or HSP90 expression. STIP1 bound to HSP70 and HSP90, and Cx43 bound to HSP40, HSP70, and HSP90 in normal H9c2 cardiomyocytes. Overexpression of STIP1 promoted the transition of Cx43-HSP70 to Cx43-HSP90 and inhibited Cx43 ubiquitination; knockdown of STIP1 resulted in the opposite effects. Inhibition of HSP90 counteracted the inhibitory effect of STIP1 overexpression on Cx43 ubiquitination. STIP1 suppresses Cx43 ubiquitination in H9c2 cardiomyocytes by promoting the transition of Cx43-HSP70 to Cx43-HSP90.

The potential roles of stress-induced phosphoprotein 1 and connexin 43 in rats with reperfusion arrhythmia.

OBJECTIVE: Connexin 43 (Cx43) is a critical gene for maintaining myocardial homeostasis. Interestingly, Cx43 and stress-induced phosphoprotein 1 (STIP1) were recorded to be lowly expressed in ischemia/reperfusion (I/R). However, their impacts on reperfusion arrhythmia (RA) remain to be explored. Our study aimed to find out the related underlying mechanisms. METHODS: After the establishment of an isolated heart model through Langendorff perfusion, the heart rate, conduction activation time, conduction velocity, and conduction direction of the left ventricle were evaluated, along with the apoptotic rate detection in the collected myocardial tissues. After the construction of a hypoxia/reoxygenation (H/R)-induced cellular model, cell apoptosis, intercellular communication, cell viability, and the content of reactive oxygen species, superoxide dismutase, malondialdehyde, and lactic dehydrogenase were measured. The expression of Cx43 and STIP1 was determined in both rat heart and cell models. The bindings of STIP3 and Cx43 to  heat shock protein 90 (HSP90) and heat shock protein 70 (HSP70) were verified. RESULTS: Relative to the corresponding controls, Cx43 and STIP1 were decreased in myocardial tissues of RA rats and H/R-stimulated H9C2 cells, where Cx43-binding HSP70 and HSP90 were respectively increased and decreased, and ubiquitination level of Cx43 was enhanced. STIP1 overexpression promoted protein expression of Cx43, intercellular communication, and cell viability, and reduced cell apoptosis and oxidative stress in H/R-stimulated H9C2 cells. CONCLUSION: STIP1 promoted Cx43 expression to improve intercellular communication and reduce oxidative stress in H/R-stimulated H9C2 cells.

Cardiac Electrophysiological Changes and Downregulated Connexin 43 Prompts Reperfusion Arrhythmias Induced by Hypothermic Ischemia-Reperfusion Injury in Isolated Rat Hearts.

The purpose of this study was to determine the utility of the monophasic action potential (MAP) changes as an arrhythmic biomarker in hypothermic ischemia-reperfusion. The hypothermic ischemia-reperfusion model was subjected to 60 min of cardioplegic arrest while the isolated rat hearts were preserved with a multidose cold K-H solution at 4 °C. During the reperfusion period, the heart's arrhythmia and monophasic action potential were also monitored. The myocardial damage was assessed using HE and TTC stains. Immunohistochemistry and Western blotting were used to assess the expression and distribution of Connexin 43 (Cx43) and Akt. Collectively, prolonged action potential durations, increased dispersion of repolarization, and downregulated and lateralized Cx43 all contribute to the derangement of electrical impulse propagation that may underlie arrhythmogenesis in the cold ischemic heart following cardioplegic arrest. MAP might be used as a biomarker for arrhythmias caused by hypothermic ischemia-reperfusion.

A Comparison of the Effect of Sevoflurane and Propofol on Ventricular Repolarisation after Preoperative Cefuroxime Infusion.

The aim of this study is to investigate the changes in QT, QTc, and Tp-e intervals and Tp-e/QT ratio on surface electrocardiogram (ECG) signals during anaesthesia induction using propofol or sevoflurane after preoperative cefuroxime infusion. Some 120 cases of gynaecological patients are randomly divided into propofol (P) and sevoflurane (S) groups (n=60). After cefuroxime (1.5 g) was infused in the two groups of patients, propofol target controlled infusion (TCI) was conducted in the P group for 5 min to realise a plasma concentration of 4 µg/ml while patients in the S group inhaled anaesthesia by infusing 1.3 MAC sevoflurane for 6 min. The 12-lead ECGs were separately collected before infusing cefuroxime (T1), after infusing cefuroxime (T2), and after infusing propofol or sevoflurane (T3) to measure QT and Tp-e intervals, calculate QTc and Tp-e/QT, and record MAP and HR. Finally, we demonstrated that QT, QTc, and Tp-e intervals and Tp-e/QT ratio had no change (P > 0.05) after cefuroxime infusion in the two groups of patients compared with that before infusing antibiotics. Moreover, after conducting preoperative cefuroxime infusion, using propofol and sevoflurane had no influence on Tp-e interval, but sevoflurane can significantly prolong QT and QTc intervals (P < 0.05).

Neuraxial adjuvants for prevention of perioperative shivering during cesarean section: A network meta-analysis following the PRISMA guidelines.

BACKGROUND: Perioperative shivering is clinically common during cesarean sections under neuraxial anesthesia, and several neuraxial adjuvants are reported to have preventive effects on it. However, the results of current studies are controversial and the effects of these neuraxial adjuvants remain unclear. AIM: To evaluate the effects of neuraxial adjuvants on perioperative shivering during cesarean sections, thus providing an optimal choice for clinical application. METHODS: A systematic review and network meta-analysis were conducted following the PRISMA (Preferred Reported Items for Systematic Review and Meta-analysis) guidelines. Analyses were performed using Review Manager 5.3 and Stata 14.0. We searched PubMed, EMBASE, Web of Science, and Cochrane Central databases for eligible clinical trials assessing the effects of neuraxial adjuvants on perioperative shivering and other adverse events during cesarean sections. Perioperative shivering was defined as the primary endpoint, and nausea, vomiting, pruritus, hypotension, and bradycardia were the secondary outcomes. RESULTS: Twenty-six studies using 9 neuraxial adjuvants for obstetric anesthesia during caesarean sections were included. The results showed that, compared with placebo, pethidine, fentanyl, dexmedetomidine, and sufentanil significantly reduced the incidence of perioperative shivering. Among the four neuraxial adjuvants, pethidine was the most effective one for shivering prevention (OR = 0.15, 95%CI: 0.07-0.35, surface under the cumulative ranking curve 83.9), but with a high incidence of nausea (OR = 3.15, 95%CI: 1.04-9.57) and vomiting (OR = 3.71, 95%CI: 1.81-7.58). The efficacy of fentanyl for shivering prevention was slightly inferior to pethidine (OR = 0.20, 95%CI: 0.09-0.43), however, it significantly decreased the incidence of nausea (OR = 0.34, 95%CI: 0.15-0.79) and vomiting (OR = 0.25, 95%CI: 0.11-0.56). In addition, compared with sufentanil, fentanyl showed no impact on haemodynamic stability and the incidence of pruritus. CONCLUSION: Pethidine, fentanyl, dexmedetomidine, and sufentanil appear to be effective for preventing perioperative shivering in puerperae undergoing cesarean sections. Considering the risk-benefit profiles of the included neuraxial adjuvants, fentanyl is probably the optimal choice.