Objective：To discuss the DNA-strand breaks at early stage of middle cerebral artery occlusion/reperfusion (MCAO/R). Methods: Neurons number and morphologic change were observed by Nissl stain method, and DNA strand b...Objective：To discuss the DNA-strand breaks at early stage of middle cerebral artery occlusion/reperfusion (MCAO/R). Methods: Neurons number and morphologic change were observed by Nissl stain method, and DNA strand breaks were in situ detected by using DNA polymerase- I Klenow fragment-mediat-ed nick end-labelling method (Klenow method). Results: Six hours after reperfusion, a few neurons in dam-aged regions appeared morphologic changes while a few Klenow-positive cells were detected (P<0. 01). Twenty-four hours after reperfusion lots of neurons showed morphologic change while the number of Klenow-positive cells immediately and remarkably increased (P<0. 01). Seventy-two hours after reperfusion the number of neurons decreased significantly and the number of Klenow-positive cells was also less than that in 24 h (P<0. 05). Conclusion: ① 24 h after reperfusion when the number of Klenow-positive cells reached peak value, DNA single-strand breaks (SSBs) took place in many Klenow-positive cells, and presumed that DNA SSBs might be an important step in DNA-damage procession which might be induced by free radicals. ② At the same time when lots of DNA SSBs were produced, many neurons in the damaged regions showed morphological change, which indicated that lots of neurons had already progressed to irreversible damages when DNA SSBs took place.展开更多
Objective To evaluate the efficacy and the mechanism of application of selective head cooling on neuronal morphological damage during postischemic reperfusion in a rabbit model.Methods 168 New Zealand rabbits were r...Objective To evaluate the efficacy and the mechanism of application of selective head cooling on neuronal morphological damage during postischemic reperfusion in a rabbit model.Methods 168 New Zealand rabbits were randomized into three groups. Group Ⅰ [n=24, (38±0.5)℃, non-ischemic control]; Group Ⅱ [n=72, (38±0.5)℃, normothermic reperfusion]; Group Ⅲ [n=72, (28±0.5)℃, selective head cooling, initiated at the beginning of reperfusion). Animals in three subgroups (n=24, each) of Group Ⅱ and Group Ⅲ had reperfused lasting for 30, 180 and 360 min respectively. Using computerized image analysis technique on morphological changes of nucleus, the degree of neuronal damage in 12 regions were differentiated into type A (normal), type B (mild damaged), type C (severely damaged) and type D (necrotic). Fourteen biochemical parameters in brain tissues were measured.[KH*2/5D]Results As compared with Group Ⅰ, the counts of type A neuron decreased progressively, and those of type B, C and D increased significantly in Group Ⅱ during reperfusion (P【0.01). In Group Ⅱ, vasoactive intestinal peptide, b-endorphine, prostacyclin, T 3 and Na +, K +-ATPase were correlated with the changes of type A; b-endorphine and thromboxane with type B; glucose and vasopressin with type C; Na +, K +-ATPase, glutamic acid, T 3 and vasoactive intestinal peptide with type D (P【0.05). As compared with Group Ⅱ, the counts of type A increased, and those of type C and D significantly decreased in Group Ⅲ (P【0.01). In Group Ⅲ, Ca 2+ , Mg 2+ -ATPase were correlated with the changes of type A, C and D (P【0.01). Conclusion Selective head cooling for sex hours during postischemic reperfusion does improve neuronal morphological outcomes in terms of morphological changes.展开更多
文摘Objective：To discuss the DNA-strand breaks at early stage of middle cerebral artery occlusion/reperfusion (MCAO/R). Methods: Neurons number and morphologic change were observed by Nissl stain method, and DNA strand breaks were in situ detected by using DNA polymerase- I Klenow fragment-mediat-ed nick end-labelling method (Klenow method). Results: Six hours after reperfusion, a few neurons in dam-aged regions appeared morphologic changes while a few Klenow-positive cells were detected (P<0. 01). Twenty-four hours after reperfusion lots of neurons showed morphologic change while the number of Klenow-positive cells immediately and remarkably increased (P<0. 01). Seventy-two hours after reperfusion the number of neurons decreased significantly and the number of Klenow-positive cells was also less than that in 24 h (P<0. 05). Conclusion: ① 24 h after reperfusion when the number of Klenow-positive cells reached peak value, DNA single-strand breaks (SSBs) took place in many Klenow-positive cells, and presumed that DNA SSBs might be an important step in DNA-damage procession which might be induced by free radicals. ② At the same time when lots of DNA SSBs were produced, many neurons in the damaged regions showed morphological change, which indicated that lots of neurons had already progressed to irreversible damages when DNA SSBs took place.
文摘Objective To evaluate the efficacy and the mechanism of application of selective head cooling on neuronal morphological damage during postischemic reperfusion in a rabbit model.Methods 168 New Zealand rabbits were randomized into three groups. Group Ⅰ [n=24, (38±0.5)℃, non-ischemic control]; Group Ⅱ [n=72, (38±0.5)℃, normothermic reperfusion]; Group Ⅲ [n=72, (28±0.5)℃, selective head cooling, initiated at the beginning of reperfusion). Animals in three subgroups (n=24, each) of Group Ⅱ and Group Ⅲ had reperfused lasting for 30, 180 and 360 min respectively. Using computerized image analysis technique on morphological changes of nucleus, the degree of neuronal damage in 12 regions were differentiated into type A (normal), type B (mild damaged), type C (severely damaged) and type D (necrotic). Fourteen biochemical parameters in brain tissues were measured.[KH*2/5D]Results As compared with Group Ⅰ, the counts of type A neuron decreased progressively, and those of type B, C and D increased significantly in Group Ⅱ during reperfusion (P【0.01). In Group Ⅱ, vasoactive intestinal peptide, b-endorphine, prostacyclin, T 3 and Na +, K +-ATPase were correlated with the changes of type A; b-endorphine and thromboxane with type B; glucose and vasopressin with type C; Na +, K +-ATPase, glutamic acid, T 3 and vasoactive intestinal peptide with type D (P【0.05). As compared with Group Ⅱ, the counts of type A increased, and those of type C and D significantly decreased in Group Ⅲ (P【0.01). In Group Ⅲ, Ca 2+ , Mg 2+ -ATPase were correlated with the changes of type A, C and D (P【0.01). Conclusion Selective head cooling for sex hours during postischemic reperfusion does improve neuronal morphological outcomes in terms of morphological changes.
