Objective:To evaluate the effect of metformin preconditioning on adenosine monophosphate-activated protein kinase(AMPK)/PTEN-induced putative protein kinase(PINK1) signaling pathway during ischemia-reperfusion (I/R) injury in diabetic rats.Methods:Thirty-six clean-grade healthy male Sprague-Dawley rats, aged 6 weeks, weighing 120-160 g, were divided into 3 groups ( n=12 each) by the random number table method: diabetic sham operation group (DS group), diabetic myocardial I/R group (DI/R group) and diabetic myocardial I/R+ metformin preconditioning group(DI/R+ Met group). After 4 weeks of feeding a high-fat and high-glucose diet, the model of type 2 diabetes mellitus was induced by a single intraperitoneal injection of 1% streptozotocin 40 mg/kg. The myocardial I/R injury was induced by blocking the anterior descending branch of the left coronary artery for 30 min followed by 120-min reperfusion in anesthetized animals. In DI/R+ Met group, metformin 200 mg/kg was given by intragastric gavage once a day within 1 week before myocardial ischemia. Blood samples from the femoral vein were collected at 120 min of reperfusion for determination of the serum creatine kinase isoenzymes (CK-MB) and cardiac troponin I (cTnI) concentrations by enzyme-linked immunosorbent assay. Then the rats were sacrificed and myocardial tissues were obtained for examination of the pathological changes(by HE staining) and for determination of the percentage of myocardial infarct size (by the double staining of Ewan blue and TTC) and expression of myocardial autophagy-related protein Beclin-1, PTEN-induced putative kinase 1 (PINK1), phosphorylated 5′-adenosine monophosphate-activating protein kinase (p-AMPK), and ratio of microtubule-associated protein 1 light chain 3Ⅱ/Ⅰ (LC3Ⅱ/Ⅰ) (by Western blot). Results:Compared with DS group, the percentage of myocardial infarct size and serum CK-MB and cTnI concentrations were significantly increased, the expression of Beclin-1, p-AMPK and PINK1 in myocardial tissues was up-regulated, the ratio of LC3II/I was increased( P<0.05), and the pathological changes were aggravated in DI/R group and DI/R+ Met group. Compared with DI/R group, the percentage of myocardial infarct size and serum CK-MB and cTnI concentrations were significantly decreased, the expression of Beclin-1, p-AMPK and PINK1 in myocardial tissues was up-regulated, the ratio of LC3Ⅱ/Ⅰ was increased ( P<0.05), and the pathological changes were significantly reduced in DI/R+ Met group. Conclusions:The mechanism by which metformin preconditioning reduces myocardial I/R injury is related to activation of AMPK/PINK1 signaling pathway and up-regulation of mitochondrial autophagy in diabetic rats.

Purpose: This study investigated whether professional identity predicts learning burnout among Chinese nursing students, and whether resilience moderates this relationship. Methods: This cross-sectional study recruited 635 students from a nursing college at a medical university in Hefei, China. Data were collected using the professional identity questionnaire, learning burnout scale for college students, and 10-item Connor-Davidson Resilience Scale. Pearson’s correlation analysis was used to investigate the relationships between variables. The mediation effect was evaluated using linear regression and the bootstrap method in SPSS. Results: Nursing students exhibited intermediate learning burnout levels (score: 54.95 ± 10.42). Professional identity was positively correlated with psychological resilience (r = .42, p < .001), whereas learning burnout was negatively correlated with professional identity (r = - .54, p < .001) and psychological resilience (r = -.57, p < .001). Psychological resilience mediated the relationship between professional identity and learning burntout to the tune of 32.8%. Conclusion Psychological resilience mediates the relationship between professional identity and learning burnout. Thus, nursing educators can mitigate student burnout by developing their students' professional identities and psychological resilience.

Purpose: This study investigated whether professional identity predicts learning burnout among Chinese nursing students, and whether resilience moderates this relationship. Methods: This cross-sectional study recruited 635 students from a nursing college at a medical university in Hefei, China. Data were collected using the professional identity questionnaire, learning burnout scale for college students, and 10-item Connor-Davidson Resilience Scale. Pearson’s correlation analysis was used to investigate the relationships between variables. The mediation effect was evaluated using linear regression and the bootstrap method in SPSS. Results: Nursing students exhibited intermediate learning burnout levels (score: 54.95 ± 10.42). Professional identity was positively correlated with psychological resilience (r = .42, p < .001), whereas learning burnout was negatively correlated with professional identity (r = - .54, p < .001) and psychological resilience (r = -.57, p < .001). Psychological resilience mediated the relationship between professional identity and learning burntout to the tune of 32.8%. Conclusion Psychological resilience mediates the relationship between professional identity and learning burnout. Thus, nursing educators can mitigate student burnout by developing their students' professional identities and psychological resilience.

Purpose: This study investigated whether professional identity predicts learning burnout among Chinese nursing students, and whether resilience moderates this relationship. Methods: This cross-sectional study recruited 635 students from a nursing college at a medical university in Hefei, China. Data were collected using the professional identity questionnaire, learning burnout scale for college students, and 10-item Connor-Davidson Resilience Scale. Pearson’s correlation analysis was used to investigate the relationships between variables. The mediation effect was evaluated using linear regression and the bootstrap method in SPSS. Results: Nursing students exhibited intermediate learning burnout levels (score: 54.95 ± 10.42). Professional identity was positively correlated with psychological resilience (r = .42, p < .001), whereas learning burnout was negatively correlated with professional identity (r = - .54, p < .001) and psychological resilience (r = -.57, p < .001). Psychological resilience mediated the relationship between professional identity and learning burntout to the tune of 32.8%. Conclusion Psychological resilience mediates the relationship between professional identity and learning burnout. Thus, nursing educators can mitigate student burnout by developing their students' professional identities and psychological resilience.

Purpose: This study investigated whether professional identity predicts learning burnout among Chinese nursing students, and whether resilience moderates this relationship. Methods: This cross-sectional study recruited 635 students from a nursing college at a medical university in Hefei, China. Data were collected using the professional identity questionnaire, learning burnout scale for college students, and 10-item Connor-Davidson Resilience Scale. Pearson’s correlation analysis was used to investigate the relationships between variables. The mediation effect was evaluated using linear regression and the bootstrap method in SPSS. Results: Nursing students exhibited intermediate learning burnout levels (score: 54.95 ± 10.42). Professional identity was positively correlated with psychological resilience (r = .42, p < .001), whereas learning burnout was negatively correlated with professional identity (r = - .54, p < .001) and psychological resilience (r = -.57, p < .001). Psychological resilience mediated the relationship between professional identity and learning burntout to the tune of 32.8%. Conclusion Psychological resilience mediates the relationship between professional identity and learning burnout. Thus, nursing educators can mitigate student burnout by developing their students' professional identities and psychological resilience.