The Experimental And Clinical Study Of Hypothermia On Acute Cerebrovascular Disease

Part OnePurpose:To investigate the effect of mild hypothermia on the content of Ca2+ Mg2+、EAA(excitatory amino acids,EAA)in rat brain tissue and ET(endothelins, ET) in plasma after acute cerebral infarction.Methods:Forty-eight Sprague-Dawley rats were randomly assigned into trial group and control group.Using the method of reformed line-thrombosis,the cerebral infarction models were established.The rats in the trial-group were cooled by mild hypothermia for half an hour,while those in the control group were subjected to no disposal.Every group was divided into 4 sub-groups according to the post-infarction disposal time.Every sub-group was composed of 6 SD rats and killed at the time points of 1 hour,2 hours,4 hours and 8 hours after infarction,respectively.Then the contents of Ca2+、Mg2+、EAA in rat brain tissues and ET in plasma were measured.Results:The contents of Ca2+(μg／mg,x±s)in rat brain tissues of the control group in 1h,2h,4h,8h were 122.61±5.55,120.73±5.21,127.37±8.40,132.53±6. 32；The contents of Ca2+(μg/mg,x±s)in rat brain tissues of the hypothermia group in 1 h,2h,4h,8h were80.11±3.3,78.1±5.07,76.30±6.82,77.65±4.38；The contents of Mg2+(μg/mg,x±s)in rat brain tissues of the control group in 1h,2h,4h, 8h were 66.93±233,65.77±1.85,63.42±3.39,61.54±3.25；The contents of Mg2+(μg／mg,x±s)in rat brain tissues of the hypothermia group in 1h,2h,4h,8h were 88.29±2.52,87.50±2.17,85.10±4.96,86.25±4.12；The contents of EAA(u mol/mg,x±s)in rat brain tissues of the control group in 1h,2h,4h,8h were 30.49±2.72,36.63±2.52,38.49±2.27,39.73±1.92；The contents of EAA(μmol/mg,x±s)in rat brain tissues of the hypothermia group in 1h,2h,4h,8h were 15.68±3.23, 15.68±3.23,18.05±2.38,19.67±1.77；The contents of ET(ng/L,x±s)in rat plasma of the control group in 1h,2h,4h,8h were 71.61±4.66,90.13±7.07,96.80± 15.51,128.20±23.47; The contents of ET (ng/L, x±s) in rat plasma of the hypothermia group in 1h,2h,4h,8h were 48.58±6.60,50.90±11.35,52.04±8.12, 57.45±4.99。The post-infarction content of Ca2+、EAA and ET of trial group increased mildly and Mg2+reduced very little. There was a significant statistical difference between the trial group and the control group.Conclusions:Mild hypothermia may significantly reverse the increase of the content of Ca2+ and EAA and the fall of Mg2+and the increment of ET in plasma as well after acute cerebral infarction in experimental animals. So as a result, mild hypothermia possesses protective effect on brain.Part twoPurpose:To investigate the effect of mild hypothermia on the content of myeloperoxidase(MPO) and cyclooxygenase-2(COX-2) in rats brain tissue after reperfusion with acute cerebral ischemia.Methods:Forty-eight Wistar rats were randomly assigned into trial group and control group.The focal cerebral ischemia and reperfusion models were induced by a suture occlusion of the left middle cerebral artery.The rats in the trial-group were cooled by mild hypothermia,while those in the control group were subjected to no disposal.Every group was divided into 4 subgroups according to the post reperfusion time.Every sub-group was composed of 6 rats and killed at the time points of 4 hour,8 hour,12 hour and 16 hour after reperfusion respectively.Then the content of MPO activity was detected by a commercial MPO kit.The expression of COX-2 were detected by immuno-Western blot and immunohistochemical method.Results:The relative values of MPO in the cortex and striatum of the control group in 4h,8h,12h,16h were 0.1782±0.0251,0.2236±0.0363,0.2469±0.0482, 0.2658±0.0586 and 0.2682±0.0460,0.2765±0.0459,0.2217±0.0356,0.1906± 0.0321; The relative values of MPO in the striatum of the trial group in 4h,8h,12h,16h were 0.0275±0.0038,0.0983±0.0122,0.1057±0.0362,0.132±0.0412 and 0.0883±0.0238,0.0952±0.0217,0.0840±0.0264,0.0632±0.0202. Compared of the values of MPO in the same time of the two groups,there was a significantly difference (P<0.01).The relative values of COX-2 in the cortex of the control group in 4h,8h,12h,16h were 1.5083±0.1160,1.5691±0.2712,1.7953±0.3322,1.8108±0.3669 and 2.367±0.2219,2.5033±0.2606,2.2785±0.2252, 1.9333±0.2100; The relative values of COX-2 in the striatum of the trial group in 4h,8h,12h,16h were 0.6407±0.0902,0.8135±0.1247,0.9509±0.1345,0.9782±0.1534 and 1.0501±0.2667,1.1430±0.2578,1.135±0.2656,0.9735±0.2353. Compared with the values of COX-2 in the same time of the two groups,there was also a significantly difference (P<0.01)Conclusion:Inflammatory reaction might lead to secondary brain injury after cerebral ischemia and reperfusion.Mild hypothermia can restrain the increase of the content of MPO and the expression of COX-2, alleviate the inflammatory reaction,reduce the secondary injury after cerebral ischemia and reperfusion in experimental animals.So as a result, mild hypotermia possesses protective effects on brain suffered from ischemia.Part threePurpose:To investigate the Changes in phagocytic index,phagocytic rate,level of serum, high C-reactive protein and tumor necrosis factor on mild hypothermia in rats after acute cerebral infarction.Methods:Fifty-four Sprague-Dawley rats were randomly assigned into mild hypothermia treatment group,cerebral infarction control group and normal control group. Using the method of reformed line thrombosis, the cerebral infarction models were established.The rats in the mild hypothermia treatment group, were cooled by mild hypothermia for half an hour,while those in the cerebral infarction control group and normal control group were subjected to no mild hypothermia. Every group was divided into 2 subgroups. Every subgroup was composed of 6SD rats. Changes in phagocytic index,phagocytic rate,level of serum, high C-reactive protein and tumor necrosis factor from 12h、24h and 36h after cerebral infarction were measured.Results:The phagocytic index, phagocytic rate,level of serum high C-reactive protein and tumor necrosis factor in the mild hypothermia treatment group were lower than those in cerebral infarction control group and normal control group.There were significant statistical differences between the mild hypothermia treatment group, cerebral infarction control group and normal control group.Conclusion:Mild hypothermia may significantly reverse the increase of phagocytic index,phagocytic rate,level of serum high C-reactive protein and tumor necrosis after acute cerebral infarction in experimental rats. So as a result, mild hypothermia possesses protective effects on brain after infarction.Part fourPurpose:To observe the effect of mild hypothermia treatment on severe cerebrovascular disease.Methods:60 cases with severe cerebrovascular disease were randomly assigned to hypothermia group and control group. In hypothermia group the patients were cooled to 34-35℃,in the control group the patients were treated by routine methods. In the hypothermia group,the Glasgow coma scores were measured before cooling,at 2 days,5 days,7 days,and the neurological function score was measured before cooling,at 2 weeks,4 weeks,12 weeks after cooling. The same score was measured at the same time in the control group,and the mortality rate in two group were recorded.Results:The scores of GCS and neurological function were found significantly different between mild hypothermia group and control group. The mortality rate in hypothermia group and control group were 7.33% and 28.12% respectively (P<0.05).Conclusion:Mild hypothermia can offer neuroprotection for the patients with severe cerebrovascular disease,reduce their mortality rate,and improve their prognosis.