Objective:To investigate the role and mechanisms of cellular FLICE-like inhibitory protein (cFLIP) in mediating oxidative stress induced by myocardial ischemia-reperfusion injury (MI/RI) in rats.Methods:Forty-eight male Sprague-Dawley rats with body weight of 180-200 g, were randomly divided into 4 groups ( n=12 per group) using a random number table: sham operation group (sham group), ischemia-reperfusion group (I/R group), virus control group (I/R+Ad-NC group), and cFLIPL-overexpressing group (I/R+Ad-cFLIPL group). A myocardial ischemia-reperfusion injury (MI/RI) model was established by ligating the left anterior descending coronary artery for 30 min followed by 3 h of reperfusion. The left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) in rats were evaluated via echocardiography, and a biochemical analyzer was used to measure the serum lactate dehydrogenase (LDH) and creatine kinase isoenzyme (CK-MB) levels to evaluate the extent of myocardial injury. The 2,3,5- triphenyl tetrazolium chloride (TTC) staining method was used to detect the infarct area of the rat myocardium, and hematoxylin and eosin (HE) staining was performed to observe the morphology of the rat myocardial tissue. Commercial kits were used to measure the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-px), and malondialdehyde (MDA). Dihydroethidium (DHE) staining was used to assess the number of reactive oxygen species (ROS)-positive cells in the myocardial tissue. Western blot analysis was performed to evaluate the protein expression of cFLIPL, Nrf2, and HO-1. Results:During MI/RI, compared with the sham group, the protein expression of cFLIPL was significantly decreased in the I/R group, and compared with the I/R+Ad-NC group, the protein expression of cFLIPL was significantly increased in the I/R+Ad-cFLIPL group (both P<0.05). Compared with sham group, the level of LDH, CK-MB, MDA, ROS-positive cell count, and myocardial infarct size were significantly increased, whereas the LVEF, LVFS, SOD, and GSH-px were significantly decreased in I/R group (all P<0.05). Compared to the I/R+Ad-NC group, the level of LDH, CK-MB, MDA, ROS-positive cell count, and myocardial infarct area were significantly decreased, whereas the LVEF, LVFS, SOD, and GSH-px were significantly increased in I/R+Ad-cFLIPL group (all P<0.05). Western blot revealed that compared with the sham group, the protein expression of Nrf2 and HO-1 in I/R group were significantly increased, and compared with the I/R+Ad-NC group, the protein expression of Nrf2 and HO-1 in the I/R + Ad-cFLIPL group were significantly increased (all P<0.05). Conclusion:Overexpression of cFLIPL can alleviate myocardial ischemia-reperfusion injury (MI/RI) in rats by activating the Nrf2/HO-1 signaling pathway to inhibit oxidative stress.

Objective To investigate the feasibility of parallel capillary bundle arrays for physiomimetic impedance modeling and establish a parametric quantification framework,thereby providing a customizable impedance characterization methodology for diverse in-vitro mock circulation researches.Methods Based on the parallel flow resistance and Poiseuille equation,a tube resistance element with multiple parallel-aligned capillary glass tubes was designed and fabricated.The resistance values of the capillary-bundle and a ball valve were measured through constant flow experiments analogous to electrical resistance measurement method.Moreover,a simple lumped-parameter mock circulation loop was constructed and the pressure and flow rate for each node of the loop were measured under different input flow waveforms.An 0D-Windkessel model corresponding to the experiment was developed.The impedance and compliance were adjusted to match the simulated and experimental pressure and flow waveforms.The accuracy of the capillary bundle impedance in pulsatile experiments was verified by using the computational resistance values.Results The constant-flow impedance calibration experiments revealed that the capillary bundle impedance remained unaffected by flow rate variations over a wide flow range.When the capillary bundle impedance was integrated into the pulsatile circulatory system and the same impedance value obtained from the constant-flow calibration was applied in the computational model,the resulting pressure and flow waveforms showed good agreement with those measured in the pulsatile experiments.However,when the ball valves with nominally identical impedance values were inserted in the pulsatile system,the calculated impedance exhibited a two-fold difference,and significant discrepancies were observed between the simulated and experimental terminal flow waveforms.Conclusions The capillary bundle impedance maintains a constant value regardless of flow rate variations.Once the calibrated resistance value is determined through constant flow experiments,it can be directly applied to pulsatile systems.This approach can provide quantitative pulsatile flow conditions for testing various medical devices.

Objective To investigate the feasibility of parallel capillary bundle arrays for physiomimetic impedance modeling and establish a parametric quantification framework,thereby providing a customizable impedance characterization methodology for diverse in-vitro mock circulation researches.Methods Based on the parallel flow resistance and Poiseuille equation,a tube resistance element with multiple parallel-aligned capillary glass tubes was designed and fabricated.The resistance values of the capillary-bundle and a ball valve were measured through constant flow experiments analogous to electrical resistance measurement method.Moreover,a simple lumped-parameter mock circulation loop was constructed and the pressure and flow rate for each node of the loop were measured under different input flow waveforms.An 0D-Windkessel model corresponding to the experiment was developed.The impedance and compliance were adjusted to match the simulated and experimental pressure and flow waveforms.The accuracy of the capillary bundle impedance in pulsatile experiments was verified by using the computational resistance values.Results The constant-flow impedance calibration experiments revealed that the capillary bundle impedance remained unaffected by flow rate variations over a wide flow range.When the capillary bundle impedance was integrated into the pulsatile circulatory system and the same impedance value obtained from the constant-flow calibration was applied in the computational model,the resulting pressure and flow waveforms showed good agreement with those measured in the pulsatile experiments.However,when the ball valves with nominally identical impedance values were inserted in the pulsatile system,the calculated impedance exhibited a two-fold difference,and significant discrepancies were observed between the simulated and experimental terminal flow waveforms.Conclusions The capillary bundle impedance maintains a constant value regardless of flow rate variations.Once the calibrated resistance value is determined through constant flow experiments,it can be directly applied to pulsatile systems.This approach can provide quantitative pulsatile flow conditions for testing various medical devices.

Objective To investigate the influence of changes in blood flow parameters on pulse rate characteristics by taking the advantage of controllable parameters in an experimental cardiopulmonary bypass system.Methods A set of human circulatory system equipped with an in vitro wrist model was established.By changing parameters such as the heart rate,wrist flow,pressure,and system compliance,a photoplethysmography pulse wave signal was obtained from the wrist model,and the time-and frequency-domain indices of pulse rate variability were extracted.Results Changes in heart rate,pressure,and system compliance caused a change in pulse shape,but the time domain indices NN50 and PNN50,which indicate pulse rate variability,were zero,and the other indices and frequency domain indices were in the very low value category.Conclusions In the absence of heart rate variability,hemodynamic changes in heart rate,wrist flow,blood pressure,and system compliance did not produce significant pulse rate variability.This study can provide a reference for studies on pulse rate variability and heart rate using more convenient wrist acquisition equipment.