Effects of dexmedetomidine on malondialdehyde and proinflammatory cytokines after tourniquet-induced ischemia-reperfusion injury in total knee arthroplasty

Protective effects of dexmedetomidine on the ischemic myocardium in patients undergoing rheumatic heart valve replacement surgery

The aim of the present study was to compare the effects of two methods of dexmedetomidine (Dex) administration on myocardial injury, inflammation and stress in ischemic myocardium during rheumatic heart valve replacement. In total, 90 patients were included in the present study and were divided into the following three groups: i) Dex group (1.0 µg/kg Dex pre-administered 10 min prior to anesthesia, then 0.5 µg/kg/h Dex for maintenance); ii) Dex pre-conditioning group (Pre-Dex; 1.0 µg/kg Dex administered 10 min prior to anesthesia, then saline for maintenance); and iii) control group (saline 10 min prior to anesthesia and saline during maintenance), with 30 patients in each group. Heart rate (HR) and mean artery pressure (MAP) were recorded at eight time-points: i) T1, pre-medication; ii) T2, 10 min post-medication; iii) T3, immediately post-intubation; iv) T4, upon skin incision; v) T5, upon sawing the sternum; vi) T6, immediately post-cardiopulmonary bypass; vii) T7, immediately post-operation; and viii) T8, 24 h post-operation. The serum cardiac troponin I (cTnI), interleukin (IL)-8, IL-10 and malondialdehyde (MDA) levels were also detected at T1, T6, T7 and T8. Blood glucose levels were detected at T1, T5, T6 and T7. In comparison with the control group, patients in the Dex group exhibited a significant increase in cardiac function, as indicated by an increase in HR, MAP and IL-10 levels, and a significant decrease in cTnI, IL-8, MDA and glucose levels. Both Dex perfusion and Dex preconditioning were able to reduce myocardial injury, inflammation, oxidative stress and stress response in rheumatic heart valve replacement surgery. However, Dex perfusion during the whole surgery was more effective than Dex preconditioning treatment. The study was registered with the Chinese Clinical Trial Registry (ChiCTR; no. ChiCTR-INR-17011955).

MicroRNA-153-3p increases autophagy in sevoflurane-preconditioned mice to protect against ischaemic/reperfusion injury after knee arthroplasty

The use of tourniquet during total knee arthroplasty (TKA) can result in ischaemia/reperfusion injury (IRI). Of interest, microRNAs (miRs) are reported to be involved in various kinds of IRI due to their ability in modulating autophagy. Therefore, the study aimed to investigate the effect of miR‐153‐3p on autophagy in IRI in vitro and in vivo under sevoflurane preconditioning. In the in vitro model, chondrocytes from naive mice were treated with 0% FBS alone or in combination with sevoflurane. Additionally, in vivo assays were conducted in mouse models with tourniquet‐induced IRI after TKA under or without sevoflurane preconditioning. The pathological observation in vivo validated that sevoflurane preconditioning protected the knee joint against IRI. Moreover, miR‐153‐3p expression was diminished in chondrocytes of the in vitro model and in cartilage tissue of the in vivo model, but its expression was appreciably up‐regulated in the presence of sevoflurane preconditioning. Mechanistic study showed that miR‐153‐3p disrupted the interaction between Bcl‐2 and Beclin1 by targeting Bcl‐2, thereby facilitating autophagy in chondrocytes under sevoflurane preconditioning. Furthermore, the experiments in human chondrocytes also verified the protective effects of miR‐153‐3p against IRI were realized through inhibiting Bcl‐2. Collectively, miR‐153‐3p overexpression blocks the interaction between Bcl‐2 and Beclin1 via down‐regulation of Bcl‐2 to promote autophagy of chondrocytes, thus protecting knee joint against IRI after TKA under sevoflurane preconditioning.