In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） follow...In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） following cerebral infarction. The pathological changes were divided into three phases： early cerebral infarction, middle cerebral infarction, and late cerebral infarction. In the early cerebral infarction phase （less than 2 hours post-infarction）, there was evidence of intracellular edema, which improved after reperfusion. This improvement was defined as the ischemic penumbra. In this phase, a high DWI signal and a low apparent diffusion coefficient were observed in the right basal ganglia region. By contrast, there were no abnormal T2WI and T2FLAIR signals. For the middle cerebral infarction phase （2-4 hours post-infarction）, a mixed edema was observed. After reperfusion, there was a mild improvement in cell edema, while the angioedema became more serious. A high DWI signal and a low apparent diffusion coefficient signal were observed, and some rats showed high T2WI and T2FLAIR signals. For the late cerebral infarction phase （4-6 hours post-infarction）, significant angioedema was visible in the infarction site. After reperfusion, there was a significant increase in angioedema, while there was evidence of hemorrhage and necrosis. A mixed signal was observed on DWI, while a high apparent diffusion coefficient signal, a high T2WI signal, and a high T2FLAIR signal were also observed. All 86 cerebral infarction patients were subjected to T2WI, T2FLAIR, and DWI. MRI results of clinic data similar to the early infarction phase of animal experiments were found in 51 patients, for which 10 patients （10/51） had an onset time greater than 6 hours. A total of 35 patients had MRI results similar to the middle and late infarction phase of animal experiments, of which eight patients （8/35） had an onset time less than 6 hours. These data suggest that defining the ＂therapeutic time window＂ as the time 6 hours after infarction may not be suitable for all patients. Integrated application of MRI sequences including T2WI, T2FLAIR, DW-MRI, and apparent diffusion coefficient mapping should be used to examine the ischemic penumbra, which may provide valuable information for identifying the ＂therapeutic time window＂.展开更多
Background The neuroprotective effect of the cyclooxygenase （COX） inhibitor has been demonstrated in acute and chronic neurodegenerative processes. But its function under cerebral ischemic conditions is unclear. Thi...Background The neuroprotective effect of the cyclooxygenase （COX） inhibitor has been demonstrated in acute and chronic neurodegenerative processes. But its function under cerebral ischemic conditions is unclear. This study was designed to evaluate the neuroprotective efficacy of emulsified flurbiprofen axetil （FA, COX inhibitor） and its therapeutic time window in a model of transient middle cerebral artery occlusion （MCAO） in rats. Methods Forty-eight male SD rats were randomly assigned into six groups （n=8 in each group）; three FA groups, vehicle, sham and ischemia/reperfusion （I/R） groups. Three doses of FA （5, 10 or 20 mg/kg, intravenous infusion） were administered just after cerebral ischemia/reperfusion （I/R）. The degree of neurological outcome was measured by the neurologic deficit score （NDS） at 24, 48 and 72 hours after I/R. Mean brain infarct volume percentage （MBIVP） was determined with 2,3,5-triphenyltetrazolium chloride （TTC） staining at 72 hours after I/R. In three other groups （n=8 in each group）, the selected dosage of 10 mg/kg was administrated intravenously at 6, 12 and 24 hours after I/R. Results The three different doses of FA improved NDS at 24, 48 and 72 hours after I/R and significantly reduced MBIVP. However, the degree of MBIVP in the FA 20 mg/kg group differed from that in FA 10 mg/kg group. Of interest is the finding that the neuroprotective effect conferred by 10 mg/kg of FA was also observed when treatment was delayed until 12-24 hours after ischemia reperfusion. Conclusion COX inhibitor FA is a promising therapeutic strategy for cerebral ischemia and its therapeutic time window could last for 12-24 hours after cerebral ischemia reperfusion, which would help in lessening the initial ischemic brain damage.展开更多
BACKGROUND： Aquaporin-4 （AQP-4） over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However, few reports hav...BACKGROUND： Aquaporin-4 （AQP-4） over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However, few reports have addressed the neuroprotective mechanisms and therapeutic times following cerebral ischemic reperfusion injury. OBJECTIVE： To explore the neuroprotective effects and ideal treatment window for picroside Ⅱ treatment of middle cerebral artery occlusion and reperfusion injury in rats. DESIGN, TIME AND SETTING; A randomized, controlled, animal experiment was performed at Institute of Cerebrovascular Diseases, Qingdao University Medical College from September 2008 to May 2009. MATERIALS： Picroside II was purchased from Tianjin Kuiqing Medical Technology, China. METHODS： A total of 165 adult, healthy, male, Wistar rats were randomly assigned to sham-surgery （n = 15）, model （n = 75）, and treatment groups （n = 75）. Rats in the model and treatment groups underwent middle cerebral artery occlusion and reperfusion through the use of an intraluminal monofilament suture on the left external-internal carotid artery, The treatment group was injected with 1.0% picroside Ⅱ （10 mg/kg） into the tail vein, and the model and sham-surgery groups were injected with 0.1 mol/L phosphate buffered saline （250 μL）. MAIN OUTCOME MEASURES： Neurological functional scores were evaluated using the Longa＇s method; cerebral infarction volume was detected through the use of tetrazolium chlodde staining; cellular apoptosis was determined through the use of the in situ end-labeling method; aquaporin-4 expression was measured using fluorescence labeling analysis and reverse transcription polymerase chain reaction technique. RESULTS： At 0.5 hour following cerebral ischemic injury, neurological functional scores were low, and a small infarction focus was detected in the ischemic cortex of the model group. Along with prolonged ischemia and an increased number of apoptosis-positive cells, AQP-4 mRNA and protein expression was increased. At 1-2 hours after ischemia, neurological scores and infarction sizes were significantly increased in the model group. Apoptotic-positive cells were widespread in the ipsilateral cortex and stdatum. In addition, AQP-4 mRNA and protein expression levels were increased. Picroside II treatment significantly decreased neurological scores and infarction volume, and reduced AQP-4 mRNA and protein expression levels compared with the model group （P 〈 0.05 or P 〈 0.01）. At 1 hour after ischemia, the therapeutic effect of picroside Ⅱ was notable （P 〈 0.01）. CONCLUSION： Picroside Ⅱ played a protective role in cerebral ischemic reperfusion injury by inhibiting apoptosis and regulating AQP-4 expression. The best therapeutic time window was 1 hour after cerebral ischemic reperfusion.展开更多
Traumatic brain injury has a complex pathophysiology that produces both rapid and delayed brain damage. Rapid damage initiates immediately after injury. Treatment of traumatic brain injury is typically delayed many ho...Traumatic brain injury has a complex pathophysiology that produces both rapid and delayed brain damage. Rapid damage initiates immediately after injury. Treatment of traumatic brain injury is typically delayed many hours, thus only delayed damage can be targeted with drugs. Delayed traumatic brain injury includes neuroinflammation, oxidative damage, apoptosis, and glutamate toxicity. Both the speed and complexity of traumatic brain injury pathophysiology present large obstacles to drug development. Repurposing of Food and Drug Administration-approved drugs may be a highly efficient approach to get therapeutics to the clinic. This review examines the preclinical outcomes of minocycline and N-acetylcysteine as individual drugs and compares them to the minocycline plus N-acetylcysteine combination. Both minocycline and N-acetylcysteine are Food and Drug Administration-approved drugs with pleiotropic therapeutic effects. As individual drugs, minocycline and N-acetylcysteine are well tolerated, with known pharmacokinetics, and enter the brain through an intact blood-brain barrier. At concentrations greater than needed for antimicrobial action, minocycline is a potent anti-inflammatory minocycline, also acts as an antioxidant and inhibits multiple enzymes that promote brain injury including metalloproteases, caspases, and polyADP-ribose-polymerase-1. N-acetylcysteine alone is also an antioxidant. It increases brain glutathione, prevents lipid oxidation, and protects mitochondria. N-acetylcysteine also acts as an anti-inflammatory as well as increases extracellular glutamate by activating the X;cystine-glutamate antitransporter. These multiple actions of minocycline and N-acetylcysteine have made them attractive candidates to treat traumatic brain injury. When first dosed within the one hour after injury, either minocycline or N-acetylcysteine improves a diverse set of therapeutic outcome measures in multiple traumatic brain injury animal models. A small number of clinical trials for traumatic brain injury have established the safety of minocycline or N-acetylcysteine and suggested that either drug has some efficacy. Preclinical studies have shown that minocycline plus N-acetylcysteine have positive synergy resulting in therapeutic effects and a more prolonged therapeutic time window not seen with the individual drugs. This review compares the actions of minocycline and N-acetylcysteine, individually and in combination. Evidence supports that the combination has greater utility to treat traumatic brain injury than the individual drugs.展开更多
Background The optimal time window for the administration of hypothermia following cerebral ischemia has been studied for decades, with disparity outcomes. In this study, the efficacy of mild brain hypothermia beginni...Background The optimal time window for the administration of hypothermia following cerebral ischemia has been studied for decades, with disparity outcomes. In this study, the efficacy of mild brain hypothermia beginning at different time intervals on brain endogenous antioxidant enzyme and energy metabolites was investigated in a model of global cerebral ischemia. Methods Forty-eight male Sprague-Dawley rats were divided into a sham-operated group, a normothermia （37℃-38℃） ischemic group and a mild hypothermic （31℃-32℃） ischemia groups. Rats in the last group were subdivided into four groups： 240 minutes of hypothermia, 30 minutes of normothermia plus 210 minutes of hypothermia, 60 minutes of normothermia plus 180 minutes of hypothermia and 90 minutes of normothermia plus 150 minutes of hypothermia （n=8）. Global cerebral ischemia was established using the Pulsinelli four-vessel occlusion model for 20 minutes and mild hypothermia was applied after 20 minutes of ischemia. Brain.tissue was collected following 20 minutes of cerebral ischemia and 240 minutes of reperfusion, and used to measure the levels of superoxide dismutase （SOD）, glutathione peroxidase （GSH-Px）, reduced glutathione （GSH） and adenosine triphosphate （ATP）. Results Mild hypothermia that was started within 0 to 60 minutes delayed the consumption of SOD, GSH-Px, GSH, and ATP （P 〈0.05 or P 〈0.01） in ischemic tissue, as compared to a normothermic ischemia group. In contrast, mild hypothermia beginning at 90 minutes had little effect on the levels of SOD, GSH-Px, GSH, and ATP （P〉0.05）. Conclusions Postischemic mild brain hypothermia can significantly delay the consumption of endogenous antioxidant enzymes and energy metabolites, which are critical to the process of cerebral protection by mild hypothermia. These results show that mild hypothermia limits ischemic injury if started within 60 minutes, but loses its protective effects when delayed until 90 minutes following cerebral ischemia.展开更多
基金supported by the National Natural Science Foundation of China,No.30960399,and No.81160181
文摘In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） following cerebral infarction. The pathological changes were divided into three phases： early cerebral infarction, middle cerebral infarction, and late cerebral infarction. In the early cerebral infarction phase （less than 2 hours post-infarction）, there was evidence of intracellular edema, which improved after reperfusion. This improvement was defined as the ischemic penumbra. In this phase, a high DWI signal and a low apparent diffusion coefficient were observed in the right basal ganglia region. By contrast, there were no abnormal T2WI and T2FLAIR signals. For the middle cerebral infarction phase （2-4 hours post-infarction）, a mixed edema was observed. After reperfusion, there was a mild improvement in cell edema, while the angioedema became more serious. A high DWI signal and a low apparent diffusion coefficient signal were observed, and some rats showed high T2WI and T2FLAIR signals. For the late cerebral infarction phase （4-6 hours post-infarction）, significant angioedema was visible in the infarction site. After reperfusion, there was a significant increase in angioedema, while there was evidence of hemorrhage and necrosis. A mixed signal was observed on DWI, while a high apparent diffusion coefficient signal, a high T2WI signal, and a high T2FLAIR signal were also observed. All 86 cerebral infarction patients were subjected to T2WI, T2FLAIR, and DWI. MRI results of clinic data similar to the early infarction phase of animal experiments were found in 51 patients, for which 10 patients （10/51） had an onset time greater than 6 hours. A total of 35 patients had MRI results similar to the middle and late infarction phase of animal experiments, of which eight patients （8/35） had an onset time less than 6 hours. These data suggest that defining the ＂therapeutic time window＂ as the time 6 hours after infarction may not be suitable for all patients. Integrated application of MRI sequences including T2WI, T2FLAIR, DW-MRI, and apparent diffusion coefficient mapping should be used to examine the ischemic penumbra, which may provide valuable information for identifying the ＂therapeutic time window＂.
基金This study was supported by a grant from the National Nature Science Foundation of China （No. 30872445）.
文摘Background The neuroprotective effect of the cyclooxygenase （COX） inhibitor has been demonstrated in acute and chronic neurodegenerative processes. But its function under cerebral ischemic conditions is unclear. This study was designed to evaluate the neuroprotective efficacy of emulsified flurbiprofen axetil （FA, COX inhibitor） and its therapeutic time window in a model of transient middle cerebral artery occlusion （MCAO） in rats. Methods Forty-eight male SD rats were randomly assigned into six groups （n=8 in each group）; three FA groups, vehicle, sham and ischemia/reperfusion （I/R） groups. Three doses of FA （5, 10 or 20 mg/kg, intravenous infusion） were administered just after cerebral ischemia/reperfusion （I/R）. The degree of neurological outcome was measured by the neurologic deficit score （NDS） at 24, 48 and 72 hours after I/R. Mean brain infarct volume percentage （MBIVP） was determined with 2,3,5-triphenyltetrazolium chloride （TTC） staining at 72 hours after I/R. In three other groups （n=8 in each group）, the selected dosage of 10 mg/kg was administrated intravenously at 6, 12 and 24 hours after I/R. Results The three different doses of FA improved NDS at 24, 48 and 72 hours after I/R and significantly reduced MBIVP. However, the degree of MBIVP in the FA 20 mg/kg group differed from that in FA 10 mg/kg group. Of interest is the finding that the neuroprotective effect conferred by 10 mg/kg of FA was also observed when treatment was delayed until 12-24 hours after ischemia reperfusion. Conclusion COX inhibitor FA is a promising therapeutic strategy for cerebral ischemia and its therapeutic time window could last for 12-24 hours after cerebral ischemia reperfusion, which would help in lessening the initial ischemic brain damage.
基金the National Natural Science Foundation of China,No. 30873391
文摘BACKGROUND： Aquaporin-4 （AQP-4） over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However, few reports have addressed the neuroprotective mechanisms and therapeutic times following cerebral ischemic reperfusion injury. OBJECTIVE： To explore the neuroprotective effects and ideal treatment window for picroside Ⅱ treatment of middle cerebral artery occlusion and reperfusion injury in rats. DESIGN, TIME AND SETTING; A randomized, controlled, animal experiment was performed at Institute of Cerebrovascular Diseases, Qingdao University Medical College from September 2008 to May 2009. MATERIALS： Picroside II was purchased from Tianjin Kuiqing Medical Technology, China. METHODS： A total of 165 adult, healthy, male, Wistar rats were randomly assigned to sham-surgery （n = 15）, model （n = 75）, and treatment groups （n = 75）. Rats in the model and treatment groups underwent middle cerebral artery occlusion and reperfusion through the use of an intraluminal monofilament suture on the left external-internal carotid artery, The treatment group was injected with 1.0% picroside Ⅱ （10 mg/kg） into the tail vein, and the model and sham-surgery groups were injected with 0.1 mol/L phosphate buffered saline （250 μL）. MAIN OUTCOME MEASURES： Neurological functional scores were evaluated using the Longa＇s method; cerebral infarction volume was detected through the use of tetrazolium chlodde staining; cellular apoptosis was determined through the use of the in situ end-labeling method; aquaporin-4 expression was measured using fluorescence labeling analysis and reverse transcription polymerase chain reaction technique. RESULTS： At 0.5 hour following cerebral ischemic injury, neurological functional scores were low, and a small infarction focus was detected in the ischemic cortex of the model group. Along with prolonged ischemia and an increased number of apoptosis-positive cells, AQP-4 mRNA and protein expression was increased. At 1-2 hours after ischemia, neurological scores and infarction sizes were significantly increased in the model group. Apoptotic-positive cells were widespread in the ipsilateral cortex and stdatum. In addition, AQP-4 mRNA and protein expression levels were increased. Picroside II treatment significantly decreased neurological scores and infarction volume, and reduced AQP-4 mRNA and protein expression levels compared with the model group （P 〈 0.05 or P 〈 0.01）. At 1 hour after ischemia, the therapeutic effect of picroside Ⅱ was notable （P 〈 0.01）. CONCLUSION： Picroside Ⅱ played a protective role in cerebral ischemic reperfusion injury by inhibiting apoptosis and regulating AQP-4 expression. The best therapeutic time window was 1 hour after cerebral ischemic reperfusion.
基金funded by an award “Minocycline plus N-acetylcysteine improves brain structure and function after experimental brain injury with clinically useful time window”(NS108190) to PJB
文摘Traumatic brain injury has a complex pathophysiology that produces both rapid and delayed brain damage. Rapid damage initiates immediately after injury. Treatment of traumatic brain injury is typically delayed many hours, thus only delayed damage can be targeted with drugs. Delayed traumatic brain injury includes neuroinflammation, oxidative damage, apoptosis, and glutamate toxicity. Both the speed and complexity of traumatic brain injury pathophysiology present large obstacles to drug development. Repurposing of Food and Drug Administration-approved drugs may be a highly efficient approach to get therapeutics to the clinic. This review examines the preclinical outcomes of minocycline and N-acetylcysteine as individual drugs and compares them to the minocycline plus N-acetylcysteine combination. Both minocycline and N-acetylcysteine are Food and Drug Administration-approved drugs with pleiotropic therapeutic effects. As individual drugs, minocycline and N-acetylcysteine are well tolerated, with known pharmacokinetics, and enter the brain through an intact blood-brain barrier. At concentrations greater than needed for antimicrobial action, minocycline is a potent anti-inflammatory minocycline, also acts as an antioxidant and inhibits multiple enzymes that promote brain injury including metalloproteases, caspases, and polyADP-ribose-polymerase-1. N-acetylcysteine alone is also an antioxidant. It increases brain glutathione, prevents lipid oxidation, and protects mitochondria. N-acetylcysteine also acts as an anti-inflammatory as well as increases extracellular glutamate by activating the X;cystine-glutamate antitransporter. These multiple actions of minocycline and N-acetylcysteine have made them attractive candidates to treat traumatic brain injury. When first dosed within the one hour after injury, either minocycline or N-acetylcysteine improves a diverse set of therapeutic outcome measures in multiple traumatic brain injury animal models. A small number of clinical trials for traumatic brain injury have established the safety of minocycline or N-acetylcysteine and suggested that either drug has some efficacy. Preclinical studies have shown that minocycline plus N-acetylcysteine have positive synergy resulting in therapeutic effects and a more prolonged therapeutic time window not seen with the individual drugs. This review compares the actions of minocycline and N-acetylcysteine, individually and in combination. Evidence supports that the combination has greater utility to treat traumatic brain injury than the individual drugs.
文摘Background The optimal time window for the administration of hypothermia following cerebral ischemia has been studied for decades, with disparity outcomes. In this study, the efficacy of mild brain hypothermia beginning at different time intervals on brain endogenous antioxidant enzyme and energy metabolites was investigated in a model of global cerebral ischemia. Methods Forty-eight male Sprague-Dawley rats were divided into a sham-operated group, a normothermia （37℃-38℃） ischemic group and a mild hypothermic （31℃-32℃） ischemia groups. Rats in the last group were subdivided into four groups： 240 minutes of hypothermia, 30 minutes of normothermia plus 210 minutes of hypothermia, 60 minutes of normothermia plus 180 minutes of hypothermia and 90 minutes of normothermia plus 150 minutes of hypothermia （n=8）. Global cerebral ischemia was established using the Pulsinelli four-vessel occlusion model for 20 minutes and mild hypothermia was applied after 20 minutes of ischemia. Brain.tissue was collected following 20 minutes of cerebral ischemia and 240 minutes of reperfusion, and used to measure the levels of superoxide dismutase （SOD）, glutathione peroxidase （GSH-Px）, reduced glutathione （GSH） and adenosine triphosphate （ATP）. Results Mild hypothermia that was started within 0 to 60 minutes delayed the consumption of SOD, GSH-Px, GSH, and ATP （P 〈0.05 or P 〈0.01） in ischemic tissue, as compared to a normothermic ischemia group. In contrast, mild hypothermia beginning at 90 minutes had little effect on the levels of SOD, GSH-Px, GSH, and ATP （P〉0.05）. Conclusions Postischemic mild brain hypothermia can significantly delay the consumption of endogenous antioxidant enzymes and energy metabolites, which are critical to the process of cerebral protection by mild hypothermia. These results show that mild hypothermia limits ischemic injury if started within 60 minutes, but loses its protective effects when delayed until 90 minutes following cerebral ischemia.
