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Objective:To evaluate the relationship between protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathway-mediated endoplasmic reticulum stress and the reduction of cerebral ischemia-reperfusion (I/R) injury by dexmedetomidine in mice by the in vivo experiment and the cell experiment. Methods:In the in vivo experiment, 20 healthy clean-grade male mice, aged 6-8 weeks, weighing 20-30 g, were divided into 4 groups ( n=5 each) using a random number table method: sham operation group (group S), sham operation+ dexmedetomidine group (group SD), cerebral I/R group (group IR) and cerebral I/R+ dexmedetomidine group (group IRD). Cerebral I/R was established by two-vessel occlusion plus hypotension.Dexmedetomidine 25 μg/kg was intraperitoneally injected at 10 min of ischemia in group IRD and at the corresponding time point in group SD.Neurological function was assessed using modified neurological severity score at 1 h of reperfusion.The animals were then sacrificed and brain tissues were taken for determination of the expression of endoplasmic reticulum stress-related proteins such as immunoglobulin heavy chain-binding protein (BIP), eukaryotic translation initiation factor 2α (EIF-2α), phosphorylated EIF-2α (p-EIF-2α), PERK and phosphorylated PERK (p-PERK) (by Wester blot). In the cell experiment, a mouse hippocampal neuronal cell line was selected and divided into 4 groups ( n=12 each) using a random number table method: control group (group C), oxygen-glucose deprivation/restoration (OGD/R) group (group OGD/R), OGD/R+ dexmedetomidine group (group OGD/R+ D) and OGD/R+ ISRIB (PERK pathway inhibitor) group (group OGD/R+ ISRIB). Cells were exposed to 94%N 2-5%CO 2-1%O 2 and incubated in a low-glucose DMEM medium for 6 h followed by restoration to establish OGD/R model.At 30 min before OGD, dexmedetomidine (final concentration 5 mmol/L) was added in group OGD/R+ D, and ISRIB (final concentration 10 mmol/L) was added in group OGD/R+ ISRIB.After 12-h restoration was completed, the cell survival rate was detected by CCK-8 assay.At 24 of restoration, the expression of endoplasmic reticulum stress-related proteins was determined by Wester blot. Results:In the in vivo experiment, compared with group S, neurobehavioral score was significantly increased and the expression of BIP, p-EIF-2α and p-PERK in brain tissues was up-regulated in group IR ( P<0.05). Compared with group IR, neurobehavioral score was significantly decreased and the expression of BIP, p-EIF-2α and p-PERK in brain tissues was down-regulated in group IRD ( P<0.05). In the cell experiment, compared with group C, the expression of BIP, p-EIF-2α, PERK and p-PERK was significantly up-regulated, and the cell survival rate was decreased in group OGD/R ( P<0.05). Compared with group OGD/R, the expression of BIP, p-EIF-2α, PERK and p-PERK was significantly down-regulated, and the cell survival rate was increased in OGD/R+ D, OGD/R+ ISRIB groups ( P<0.05). Compared with group OGD/R+ ISRIB, the expression of PERK was significantly down-regulated ( P<0.05) and no significant change was found in the other parameters in group OGD/R+ D ( P>0.05). Conclusion:The mechanism by which dexmedetomidine reduces cerebral I/R injury may be related to inhibiting PERK pathway-mediated endoplasmic reticulum stress in mice.
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Objective:To evaluate the relationship between silence information regulator 1 (SIRT1) and signal transducers and activators of transcription 3 (STAT3) acetylation during high glucose-induced cardiac microvascular endothelial cell injury.Methods:Cardiac microvascular endothelial cells of Sprague-Dawley rats were cultured.The cells at the logarithmic growth phase were selected and divided into 3 groups ( n=24 each) using a random number table method: control group (C group), high glucose group (HG group) and high glucose+ SIRT1 agonist SRT1720 group (HG+ SRT group). The cardiac microvascular endothelial cells were seeded in a 6- or 96-well cell culture plate at a density of 2×10 5 cells/ml.When the cell density reached 50%, the culture medium was then replaced with high-glucose (glucose 33 mmol/L) DMEM culture medium containing with 10% fetal bovine serum and 1% double antibody in HG and HG+ SRT groups.In group HG+ SRT, 20 μmol/L SRT1720 was added simultaneously, and the cells were cultured at 37 ℃ in an incubator with 5% CO 2 for 24 h. The cell viability was determined by CCK-8 assay, the activity of superoxide dismutase (SOD) was detected using a spectrophotometer, the levels of lactic dehydrogenase (LDH), interleukin-6 (IL-6) and tumor necrosis factor-β (TNF-β) in the supernatant were detected by enzyme-linked immunosorbent assay, and the expression of SIRT1, acetylated STAT3 (ac-STAT3) and phosphorylated STAT3 (p-STAT3) was determined by Western blot. Results:Compared with C group, the cell viability and SOD activity were significantly decreased, levels of LDH, IL-6 and TNF-β in the supernatant were increased, expression of SIRT1 was down-regulated, and expression of ac-STAT3 and p-STAT3 was up-regulated in group HG and group HG+ SRT ( P<0.05). Compared with group HG, the cell viability and SOD activity were significantly increased, levels of LDH, IL-6 and TNF-β in the supernatant were decreased, expression of SIRT1 was up-regulated, and expression of ac-STAT3 and p-STAT3 was down-regulated in group HG+ SRT ( P<0.05). Conclusion:SIRT1 can alleviate high glucose-induced cardiac microvascular endothelial cell injury by promoting STAT3 deacetylation.
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Objective:To evaluate the role of protein O-linked beta-N-acetylglucosaminylation (O-GlcNAcylation) modification in oxidative stress injury in nerve cells of mice subjected to oxygen-glucose deprivation and restoration (OGD/R).Methods:The standard mouse hippocampal neuron cell line was inoculated on a culture plate or dish at a density of 5×10 4 cells/ml and divided into 4 groups ( n=20 each) using a random number table method: normal group (N group), O-(connection)N-acetylglucosamine hydrolase (OGA) inhibitor Thiamet G group (T group), OGD/R group (D/R group) and Thiamet G+ OGD/R complex sugar group (T-D/R group). The cells were exposed to a mixed gas of 94% N 2-5% CO 2-1% O 2 for 6 h in a low-glucose medium, then medium was replaced with a common medium for restoring oxygen and glucose, and the cells were cultured for 12 h. Thiamet G at a final concentration of 1 mmol/L was added to the culture medium at 4 h before OGD/R in T-D/R group, and the medium was replaced with a medium containing Thiamet G at a final concentration of 1 mmol/L at 4 h before extraction of cellular proteins.After oxygen and glucose restoration was completed, the accumulation of cellular ROS was measured using DCFH-DA staining, mitochondrial membrane potential was measured using Jc-1 staining, O-GlcNAc modification was determined by immunofluorescence, and the expression of nuclear factor E2-related factor 2 (Nrf2), c-Jun N-terminal kinase (JNK), phosphorylated JNK (p-JNK), and p53 tumor suppressor gene (p53) was detected using Western blot. Results:Compared with group N, the expression of O-GlcNAc in nerve cells was significantly up-regulated in group T, and the accumulation of ROS in nerve cells was significantly increased, JC-1 monomer was increased, JC-1 polymer was decreased, Nrf2 expression was down-regulated, and the expression of p-JNK and p53 was up-regulated in group D/R, and the expression of O-GlcNAc in nerve cells was up-regulated, the accumulation of ROS was increased, the polymerization of JC-1 monomer and JC-1 was increased, Nrf2 expression was down-regulated, and the expression of p-JNK and p53 was up-regulated in group T-D/R ( P<0.05). Compared with group D/R, the expression of O-GlcNAc in nerve cells was significantly up-regulated, the accumulation of ROS was decreased, JC-1 monomer was decreased, JC-1 polymer was increased, the expression of Nrf2 was up-regulated, and the expression of p-JNK and p53 was down-regulated in group T-D/R ( P<0.05). Conclusion:When mouse nerve cells are subjected to OGD/R, the protein O-GlcNAc modification as an endogenous protective mechanism is enhanced, which can reduce oxidative stress injury, and the mechanism may be related to regulating the Nrf2-mediated JNK pathway.
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Objective:To evaluate the role of c-Abl in myocardial ischemia-reperfusion (I/R) injury in diabetic rats.Methods:Sixty male SPF-grade healthy Sprague-Dawley rats, aged 7-9 weeks, weighing 210-230 g, were divided into 6 groups by a random number table method: sham operation group (S group, n=6), myocardial I/R group (IR group, n=12), diabetic sham operation group (DS group, n=6), diabetic myocardial I/R group (DIR group, n=12), diabetic myocardial I/R plus AVV9-siRNA-c-Abl group (DIR+ c-Abl group, n=12), and diabetic myocardial I/R plus AVV9-GFP group (DIR+ GFP group, n=12). One percent streptozotocin 60 mg/kg was intraperitoneally injected to induce type 1 diabetes mellitus.AVV9-siRNA-c-Abl and AVV9-GFP 1×10 12 mg/kg were slowly injected at 4 weeks after establishing the model in DIR+ c-Abl and DIR+ GFP groups.Myocardial ischemia was induced by 30 min occlusion of left anterior descending branch (LAD) of coronary artery followed by 2 h reperfusion at 8 weeks after establishing the model.At the end of reperfusion, left ventricular systolic pressure (LVSP) and the maximum rate of increase and decrease of left ventricular systolic pressure (±dp/dt max) were monitored, and blood samples were collected for determination of the concentrations of serum lactic dehydrogenase (LDH) and creatine kinase-MB (CK-MB) (by enzyme-linked immunosorbent assay)and myocardial infarct size (except group S and group DS). Myocardial tissues were obtained for determination of the apoptosis index of cardiomyocytes(by TUNEL staining), expression of c-Abl, p53 and activated caspase-3 (by Western blot), and binding of c-Abl and p53 (c-Abl/p53) (by co-immunoprecipitation method). Results:LVSP and ±dp/dt max were significantly decreased, serum LDH and CK-MB concentrations were increased, apoptosis index and c-Abl/p53 were increased, and the expression of c-Abl, p53 and activated caspase-3 was up-regulated in group IR when compared with group S and in group DIR as compared with group DS ( P<0.05). Compared with group DIR, the LVSP and ± dp/dt max were significantly increased, serum LDH and CK-MB concentrations were decreased, myocardial infarct size was decreased, apoptosis index and c-Abl/p53 were decreased, and the expression of c-Abl, p53 and activated caspase-3 was down-regulated in group DIR+ c-Abl ( P<0.05), and no significant change was found in the parameters mentioned above in group DIR+ GFP ( P>0.05). Conclusion:c-Abl is involved in the pathophysiological process of myocardial I/R injury probably by activating p53 signaling pathway in diabetic rats.
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Objective To compare the effect of pedicles screw fixation through entry point of the “人" shape crest and traditional entry point (Weinstein method). Methods Ninety-two patients of lumbar spine disorders were treated by pedicles screw fixation combined with bone grafting through posterior approach. The screws were placed through the traditional entry point among 45 patients (group A, transverse process method, 186 screws), the others were through entry point of the “人" shape crest (group B, “人" shape crest method, 196 screws). The condition of accuracy of screw placement, operation time, bleeding amount and injury were compared. Results All patients accepted the examination of X-ray and CT scan after operation. The rate of screw bad placement was 6.5% in group A and 2.0% in group B, the incidence of injury of nerve and blood vessel was 8.9% in group A and 2.1% in group B. The accuracy of screw placement, operational time and bleeding amount in group B were significantly better than those in group A (P