BACKGROUND: Rapid and complete reperfusion has been widely adopted in the treatment of patients with acute myocardial infarction(AMI), but this process sometimes can cause severe reperfusion injury. This study aimed t...BACKGROUND: Rapid and complete reperfusion has been widely adopted in the treatment of patients with acute myocardial infarction(AMI), but this process sometimes can cause severe reperfusion injury. This study aimed to investigate different patterns of post-conditioning in acute myocardial ischemia-reperfusion injury, and to detect the role of mitogen activated protein kinase(MAPK) during the injury.METHODS: Rats were randomly divided into five groups: sham group, reperfusion injury(R/I) group, gradually decreased reperfusion group(GDR group, 30/10-25/15-15/25-10/30 seconds of reperfusion/ischemia), equal reperfusion group(ER group, 20/20 seconds reperfusion/ischemia, 4 cycles), and gradually increased reperfusion group(GIR group, 10/30-15/25-25/15-30/10 seconds of reperfusion/ischemia). Acute myocardial infarction and ischemic post-conditioning models were established in the rats. Six hours after reperfusion, 3 rats from each group were sacrificed and myocardial tissues were taken to measure the expressions of phosphorylation of extracellular signalregulated protein kinase(P-ERK), phosphorylated c-Jun N-terminal kinase(P-JNK), mitogen-activated protein kinase p38(p38 MAPK), tumor necrosis factor-α(TNF-α), caspases-8 in the myocardial tissue, and cytochrome c in the cytosol using Western blot. Hemodynamics was measured at 24 hours after reperfusion, the blood was drawn for the determination of cardiac enzymes, and the heart tissue was collected for the measurement of apoptosis using TUNEL. One-way analysis of variance and the Q test were employed to determine differences in individual variables between the 5 groups.RESULTS: Three post-conditioning patterns were found to provide cardioprotection(P<0.05) compared with R/I without postconditioning. GIR provided the best cardioprotection effect, followed by ER and then GDR. Apoptotic index and serum marker levels were reduced more signifi cantly in GIR than in ER(P<0.05). The enhanced cardioprotection provided by GIR was accompanied with significantly increased levels of P-ERK 1/2(1.82±0.22 vs. 1.54±0.32, P<0.05), and lower levels of p-JNK, p38 MAPK, TNF-α, caspase-8, caspase-9 and cytochrome in the cytoplasm(P<0.05), compared with ER. The infarct size was smaller in the GIR group than in the ER group, but this difference was not significant(16.30%±5.22% vs. 20.57%±6.32%, P<0.05). All the measured variables were improved more signifi cantly in the GIR group than in the GDR group(P<0.05).CONCLUSION: Gradually increased reperfusion in post-conditioning could attenuate reperfusion injury more significantly than routine method, thereby the MAPK pathway plays an important role in this process.展开更多
Neutral red is kind of biologic colourant and acidity-basicity indicator. Radiation degradation of neutral red in aqueous solution was done by γ-Ray. The removal rate of chemical oxygen demand, total organic carbon, ...Neutral red is kind of biologic colourant and acidity-basicity indicator. Radiation degradation of neutral red in aqueous solution was done by γ-Ray. The removal rate of chemical oxygen demand, total organic carbon, chroma and the changing of pH value were studied under various conditions. With the increase of absorbed doses, the chemical oxygen demand and chroma decreased conspicuously. The absorbed dose rate has little effect on the degradation of neutral red. When the absorbed doses are the same, the chemical oxygen demand and chroma decreased more obviously with the increase of neutral red concentration. Weak basic condition and proper H2O2 addiation are propitious to removal of chemical oxygen demand of neutral red.展开更多
Background： Calreticulin （CRT） is major Ca^2＋-binding chaperone mainly resident in the endoplasmic reticulum （ER） lumen. Recently, it has been shown that non-ER CRT regulates a wide array of cellular responses. ...Background： Calreticulin （CRT） is major Ca^2＋-binding chaperone mainly resident in the endoplasmic reticulum （ER） lumen. Recently, it has been shown that non-ER CRT regulates a wide array of cellular responses. We previously found that CRT was up-regulated during hypoxia/ reoxygenation （H/R） and this study was aimed to investigate whether CRT nuclear translocation aggravates ER stress （ERS）-associated apoptosis during H/R injury in neonatal rat cardiomyocytes. Methods： Apoptosis rate and lactate dehydrogenase （LDH） leakage in culture medium were measured as indices of cell injury. lmmunofluorescence staining showed the morphological changes of ER and intracellular translocation of CRT. Western blotting or reverse transcription polymerase chain reaction was used to detect the expression of target molecules. Results： Compared with control, H/R increased apoptosis rate and LDH activity. The ER became condensed and bubbled, and CRT translocated to the nucleus. Western blotting showed up-regulation of CRT, Nrf2, activating transcription factor 4 （ATF4）, CHOP and caspase-12 expression after H/R. Exogenous CRT overexpression induced by plasmid transfection before H/R increased cell apoptosis, LDH leakage, ER disorder, CRT nuclear translocation and the expression of ERS-associated molecules. However, administration of the ERS inhibitor, taurine, or CRT siRNA alleviated cell injury, ER disorder, and inhibited ERS-associated apoptosis. Conclusions： Our results indicated that during H/R stress, CRT translocation increases cell apoptosis and LDH leakage, aggravates ER disorder, up-regulates expression of nuclear transcription factors, Nrf2 and ATF4, and activates ERS-associated apoptosis.展开更多
基金Acknowledgements This work was supported by International Science and Technology Cooperation Project （2010DFA31690）, National Natural Science Foundation of China （81030063 and 81170140） and China Postdoctoral Science Foundation （2014M562608）. The authors declare no conflict of interests regarding the publication of this paper.
基金supported by grants from the National Science Foundation of China(30740080)Dean fund of the General Hospital of Jinan Military Command(2011Q08)
文摘BACKGROUND: Rapid and complete reperfusion has been widely adopted in the treatment of patients with acute myocardial infarction(AMI), but this process sometimes can cause severe reperfusion injury. This study aimed to investigate different patterns of post-conditioning in acute myocardial ischemia-reperfusion injury, and to detect the role of mitogen activated protein kinase(MAPK) during the injury.METHODS: Rats were randomly divided into five groups: sham group, reperfusion injury(R/I) group, gradually decreased reperfusion group(GDR group, 30/10-25/15-15/25-10/30 seconds of reperfusion/ischemia), equal reperfusion group(ER group, 20/20 seconds reperfusion/ischemia, 4 cycles), and gradually increased reperfusion group(GIR group, 10/30-15/25-25/15-30/10 seconds of reperfusion/ischemia). Acute myocardial infarction and ischemic post-conditioning models were established in the rats. Six hours after reperfusion, 3 rats from each group were sacrificed and myocardial tissues were taken to measure the expressions of phosphorylation of extracellular signalregulated protein kinase(P-ERK), phosphorylated c-Jun N-terminal kinase(P-JNK), mitogen-activated protein kinase p38(p38 MAPK), tumor necrosis factor-α(TNF-α), caspases-8 in the myocardial tissue, and cytochrome c in the cytosol using Western blot. Hemodynamics was measured at 24 hours after reperfusion, the blood was drawn for the determination of cardiac enzymes, and the heart tissue was collected for the measurement of apoptosis using TUNEL. One-way analysis of variance and the Q test were employed to determine differences in individual variables between the 5 groups.RESULTS: Three post-conditioning patterns were found to provide cardioprotection(P<0.05) compared with R/I without postconditioning. GIR provided the best cardioprotection effect, followed by ER and then GDR. Apoptotic index and serum marker levels were reduced more signifi cantly in GIR than in ER(P<0.05). The enhanced cardioprotection provided by GIR was accompanied with significantly increased levels of P-ERK 1/2(1.82±0.22 vs. 1.54±0.32, P<0.05), and lower levels of p-JNK, p38 MAPK, TNF-α, caspase-8, caspase-9 and cytochrome in the cytoplasm(P<0.05), compared with ER. The infarct size was smaller in the GIR group than in the ER group, but this difference was not significant(16.30%±5.22% vs. 20.57%±6.32%, P<0.05). All the measured variables were improved more signifi cantly in the GIR group than in the GDR group(P<0.05).CONCLUSION: Gradually increased reperfusion in post-conditioning could attenuate reperfusion injury more significantly than routine method, thereby the MAPK pathway plays an important role in this process.
文摘Neutral red is kind of biologic colourant and acidity-basicity indicator. Radiation degradation of neutral red in aqueous solution was done by γ-Ray. The removal rate of chemical oxygen demand, total organic carbon, chroma and the changing of pH value were studied under various conditions. With the increase of absorbed doses, the chemical oxygen demand and chroma decreased conspicuously. The absorbed dose rate has little effect on the degradation of neutral red. When the absorbed doses are the same, the chemical oxygen demand and chroma decreased more obviously with the increase of neutral red concentration. Weak basic condition and proper H2O2 addiation are propitious to removal of chemical oxygen demand of neutral red.
基金This study was supported by the National Natural Science Foundation of China （No. 81170140 and No. 31471094）.
文摘Background： Calreticulin （CRT） is major Ca^2＋-binding chaperone mainly resident in the endoplasmic reticulum （ER） lumen. Recently, it has been shown that non-ER CRT regulates a wide array of cellular responses. We previously found that CRT was up-regulated during hypoxia/ reoxygenation （H/R） and this study was aimed to investigate whether CRT nuclear translocation aggravates ER stress （ERS）-associated apoptosis during H/R injury in neonatal rat cardiomyocytes. Methods： Apoptosis rate and lactate dehydrogenase （LDH） leakage in culture medium were measured as indices of cell injury. lmmunofluorescence staining showed the morphological changes of ER and intracellular translocation of CRT. Western blotting or reverse transcription polymerase chain reaction was used to detect the expression of target molecules. Results： Compared with control, H/R increased apoptosis rate and LDH activity. The ER became condensed and bubbled, and CRT translocated to the nucleus. Western blotting showed up-regulation of CRT, Nrf2, activating transcription factor 4 （ATF4）, CHOP and caspase-12 expression after H/R. Exogenous CRT overexpression induced by plasmid transfection before H/R increased cell apoptosis, LDH leakage, ER disorder, CRT nuclear translocation and the expression of ERS-associated molecules. However, administration of the ERS inhibitor, taurine, or CRT siRNA alleviated cell injury, ER disorder, and inhibited ERS-associated apoptosis. Conclusions： Our results indicated that during H/R stress, CRT translocation increases cell apoptosis and LDH leakage, aggravates ER disorder, up-regulates expression of nuclear transcription factors, Nrf2 and ATF4, and activates ERS-associated apoptosis.
