Objective To systematically evaluate the clinical effects of remote ischaemic preconditioning (RIPC) in elective vascular surgery. Methods Electronic searches were conducted in The Cochrane Library, PubMed, EMbase, Web of Science, CNKI, Wanfang Data, VIP Database, and CBM. Relevant randomized controlled trials (RCTs) were screened according to inclusion and exclusion criteria. Meta-analysis was performed using RevMan 5.3 software, and the risk of bias was assessed using the Cochrane risk of bias tool. Results A total of 15 studies involving 1 382 patients were included. The meta-analysis results showed no statistically significant difference between RIPC and non-RIPC groups in reducing perioperative mortality in elective vascular surgery (P>0.05). There were also no statistically significant differences between the two groups of vascular surgery patients regarding the incidence of myocardial infarction, renal injury, postoperative stroke, postoperative length of hospital stay, duration of surgery or total anesthesia time, or the incidence of limb injury, arrhythmia, heart failure, and pneumonia (P>0.05). Conclusion For patients undergoing elective vascular surgery, there are no significant differences between RIPC and non-RIPC in terms of perioperative mortality and other clinical endpoint outcomes.

Objective To observe the effect of melatonin (MT) on retinal apoptosis in rats with ischemia-reperfusion injury (RIRI).Methods A total of 54 male healthy Sprague-Dawley adult rats were randomly divided into the normal control (CON) group (6 rats), RIRI group (24 rats) and MT group (24 rats). The rats of RIRI and MT group were induced using suture-occluded methods to establish RIRI model. The rats of MT group were injected with MT in the left carotid artery 30 minutes after RIRI, and RIRI group was injected with the same amount of saline. On 6, 24 hours and 3, 7 days after RIRI, the morphological changes of retina were evaluated by hematoxylin and eosin (HE) staining; the effects of MT on retinal cell apoptosis and Nrf2,HO-1 proteins were examined by immunohistochemistry staining. The correlation between active Caspase-3 and Nrf2 protein, active Caspase-3 and HO-1 protein in MT group were analyzed by linear regression analysis. Results HE staining results showed that the morphology of retinal cells was regular and retinal cells were well arranged in the CON and MT group. In the RIRI group, both the thickness of inner retinal layer and the number of retinal ganglion cells (RGC) were decreased. On 6, 24 hours and 3, 7 days after RIRI, the thickness of inner retinal layer (F=16.710, 62.303, 68.389, 57.132;P<0.01) and RGC number (F=24.250, 11.624, 14.155, 32.442;P<0.05) in MT group were more than those in RIRI group. Immunohistochemistry staining results showed that less active Caspase-3+ cells were observed in MT group as compared with those in RIRI group at each time points (F=49.118, 134.173, 76.225, 18.385;P<0.01). There were more Nrf2+ (F=11.041, 31.480, 59.246, 6.740;P<0.05) and HO-1+ cells (F=128.993, 21.606, 51.349, 8.244;P<0.05) in MT group as compared with those in RIRI group at each time points. Linear regression analysis results showed that the difference of active Caspase-3+cells were all linearly correlated with the Nrf2+ cells and HO-1+cells in the MT group (r2=0.810, 0.730;P<0.01). Conclusion MT could reduce retinal cell apoptosis in RIRI rats, and its mechanism may be associated with increased Nrf2 and HO-1 expression, reduced active Caspase-3 expression.