脑温对大脑灶性脑缺血再灌注损伤的影响

目的 研究预高温和缺血时轻度高温、亚低温对脑缺血再灌注损伤组织脂质过氧化和缺血脑组织病变的影响。方法 75只Wistar大鼠按不同脑温和缺血条件被随机分为生化组（5组，n=7)和病理组（5组，n=8),采用Nagasawa脑缺血模型，观察脑缺血再灌注损伤组织超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH－Px)、还原型谷胱甘肽（GSH）、丙二醛（MDA）及缺血脑组织病理变化。结果 轻度高温加重常温脑缺血组织SOD、GSH的降低和MDA的增高，使GSH－Px呈降低趋势，而亚低温相反；预高温对常温脑缺血各项指标影响不显。轻度高温组脑缺血病理损伤最重，亚低温和预高温有改善脑缺血损伤的作用。结论 高温加重而亚低温抑制脑血损伤，分别与其增加或减少内源性抗氧化酶消耗、降低或增强缺血脑组织清除氧自由基的能力有关；预高温对缺血脑组织有保护作用，未能肯定此作用与内源性抗氧化酶消耗减少和缺血脑组织清除氧自由基的能力增强有关。     

不同脑温状态地西泮对大鼠脑缺血再灌注氧自由基的影响

目的观察轻度高温、常温、亚低温状态下,地西泮对大鼠脑缺血组织SOD、GSH-Px、GSH及MDA的影响。方法建立大鼠可复流大脑中动脉闭塞模型,诱导目标脑温,分别测定各组SOD、GSH-Px、GSH及MDA含量。结果①与常温假手术组比较,常温脑缺血对照组SOD、GSH-Px、GSH均显著降低（P〈0.001）,MDA显著增高（P〈0.001）。②与常温脑缺血对照组比较,常温地西泮组GSH-Px、GSH均显著增高（P〈0.01-0.001）,MDA显著降低（P〈0.001）。③与常温地西泮组比较,轻度高温地西泮组SOD、GSH-Px、GSH均显著降低（P〈0.001）,MDA显著增高（P〈0.001）;亚低温地西泮组SOD、GSH-Px、GSH均显著增高（P〈0.001）,MDA显著降低（P〈0.001）。结论①常温脑缺血组织SOD、GSH-Px、GSH降低,MDA增高,可能对缺血脑组织产生不利影响。②脑缺血时给予地西泮,在轻度高温状态下不能增高SOD、GSH-Px、GSH水平及不能降低MDA水平,在常温状态下可增高GSH-Px、GSH水平及降低MDA水平,在亚低温状态下可进一步增高SOD、GSH-Px、GSH水平及降低MDA水平。提示轻度高温状态下地西泮可能不具有抑制脑缺血再灌注损伤的作用,常温状态下地西泮可能具有抑制脑缺血再灌注损伤的作用,亚低温状态下地西泮可能具有显著的抑制脑缺血再灌注损伤的作用。     

老年大鼠全脑缺血再灌注所致神经元凋亡及氧化损伤的机制

目的　观察老年大鼠全脑缺血再灌注后神经元凋亡的规律 ,并探讨氧化损伤的机制。方法　利用四血管结扎法 ,建立老年大鼠全脑缺血再灌注模型 ,分别于缺血再灌注后 6h、1、3、5、7d计数海马锥体神经元存活数 ,原位末端标记法计数凋亡神经元数 ,电镜观察超微结构变化 ,并测定脑组织丙二醛 (MDA)含量和超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶 (GSH Px)活性。结果　老年大鼠全脑缺血再灌注后海马CA1区神经元凋亡损伤在再灌注后第 3天损伤最重 ,存活神经元数显著减少 ,电镜显示有凋亡改变。脑组织SOD和GSH Px活性降低 ,MDA含量升高 ,再灌注后 3d最为明显。结论　全脑缺血再灌注神经元凋亡损伤与氧自由基水平升高 ,抗氧化酶活性降低有关。     

银杏叶提取物对不同脑温状态大鼠缺血脑组织病理影响的研究

目的探讨银杏叶提取物(GBE)对不同脑温状态下大鼠缺血脑组织病理改变的影响。方法将24只Wistar大鼠随机分为常温假手术组、常温脑缺血对照组、亚低温脑缺血组、轻度高温银杏叶组、常温银杏叶组、亚低温银杏叶组(n=4),建立各组大鼠大脑中动脉缺血2h/再灌注4h模型,采用光镜、电镜观察各组大鼠缺血脑组织病理改变特点。结果亚低温银杏叶组、亚低温脑缺血组、常温银杏叶组、常温脑缺血对照组、轻度高温银杏叶组等各组大鼠缺血脑组织病理损伤范围及程度呈依次加重趋势。结论 GBE对脑缺血的保护作用受不同脑温影响,37.0～37.5℃常温状态下GBE的神经保护作用有限,而32.0～32.5℃亚低温状态下GBE对脑缺血的保护作用增强;亚低温和GBE联合干预,增强对脑缺血的保护。     

地西泮联合亚低温对大鼠脑缺血损伤病理的影响

目的 探讨地西泮联合亚低温治疗对大鼠局灶脑缺血组织病理损伤的影响.方法 20只Wistar大鼠随机分为假手术组、脑缺血对照组、轻度高温地西泮组、常温地西泮组及亚低温地西泮组(每组4只).用线栓法制作大鼠脑缺血模型,地西泮组在缺血前30 min及缺血后2 h腹腔注射地西泮(10 mg/kg).诱导目标脑温,采用光镜、电镜观察各组病理特点.结果 轻度高温、常温、亚低温状态下地西泮治疗组随脑温降低,缺血脑组织病理损伤依次减轻,地西泮联合亚低温治疗明显改善缺血脑组织病理学特征.结论 地西泮联合亚低温治疗对脑缺血的保护作用增强.     

地西泮对大鼠不同脑温脑缺血组织γ-氨基丁酸的影响

目的研究轻度高温、常温、亚低温状态下,地西泮对大鼠脑缺血组织γ-氨基丁酸（GABA）的影响。方法建立大鼠可复流大脑中动脉闭塞模型,诱导目标脑温,用HPLC荧光法检测脑缺血组织GABA含量。结果与常温假手术组比较,常温脑缺血对照组GABA无显著改变,而常温地西泮组GABA显著增高（P〈0.01）。与常温脑缺血对照组比较,常温及轻度高温地西泮组GABA无显著改变,而亚低温地西泮组GABA显著增高（P〈0.001）。与常温地西泮组比较,轻度高温地西泮组GABA无显著改变,而亚低温地西泮组GABA显著增高（P〈0.001）。结论常温脑缺血时,GABA无显著增高,可能对缺血脑组织产生不利影响。在常温及轻度高温状态下给予地西泮,均不能显著增高缺血脑组织GABA水平,且GABA水平随脑温的升高而稍有降低,没能显示出地西泮有“抑制性保护”作用,其“抑制性保护”作用似乎有限。亚低温状态下给予地西泮,可显著增高缺血脑组织GABA水平,显示出地西泮有“抑制性保护”作用,因此亚低温可能有利于增强地西泮的神经保护作用。     

抗纤灵冲剂对肾缺血再灌注的实验研究

目的 :研究中成药抗纤灵冲剂对于缺血再灌注大鼠组织中超氧化物歧化酶 (SOD )、谷胱甘肽过氧化物酶 (GSH -PX )、丙二醛 (MDA )的影响 ,进一步探讨抗纤灵冲剂抗氧自由基的作用机制。方法 :使用南京聚力生物医学工程研究所提供的试剂盒测定大鼠缺血再灌注肾组织中SOD、MDA、GSH -PX含量的变化及抗纤灵冲剂、大黄、丹参对其的影响。结果 :大鼠缺血再灌注肾组织中的SOD、GSH -PX显著降低 ,MDA显著增高 ,而抗纤灵冲剂及大黄、丹参均能明显提高组织SOD、GSH -PX ,降低MDA含量。结论 :抗纤灵冲剂及大黄、丹参能明显提高肾组织中SOD、GSH -PX ,降低MDA含量 ,这可能是其治疗慢性肾功能不全的主要机制之一。     

VE拮抗氟对大鼠脑氧化损伤的实验观察

目的 研究不同浓度NaF对大鼠脑的氧化损伤作用及VE的保护作用。方法 大鼠脑匀浆施加不同浓度NaF及VE处理因素后，分别测定脂质过氧化产物丙二醛(MDA)和抗氧化酶(SOD)、谷胱甘肽过氧化物酶(GSH—Px)的活性。结果 不同浓度NaF与大鼠脑匀浆在37℃水浴1h时，随着NaF浓度的增加，MDA逐渐升高；并且能抑制大鼠脑匀浆的SOD、GSH—Px活性；VE能拮抗NaF诱导的大鼠脑匀浆脂质过氧化作用，提高GSH—Px活性。结论 NaF对大鼠脑损伤的机制可能与其抑制抗氧化酶的活性，造成脑组织氧化损伤作用增强有关。     

局灶脑缺血再灌注脑温对抑制性氮基酸的影响

目的 研究轻度、亚低温对局灶脑缺血抑制性氨基酸的影响。方法 建立大鼠大脑中动脉缺血再灌注模型,诱导目标脑温,用HPLC荧光法检测脑组织GABA含量。结果 轻度高温组GABA短暂增高后下降,亚低温组GABA持续增高。结论 轻度高温使脑内GABA水平下调,在加重缺血神经元损伤方面起着不容忽视的作用：亚低温使GABA水平持续上调,在保护缺血神经元方面起重要作用。     

肢体反复短暂缺血预处理在大鼠脑缺血再灌注损伤中的保护作用

目的 探讨肢体反复短暂缺血预处理(LIP)在大鼠脑缺血再灌注损伤中可能的脑保护机制.方法 随机将42只成年健康雄性Wistar大鼠分为7组,假手术组、脑缺血组、脑缺血再灌注组、预处理0 h组、预处理6 h组、预处理12 h组、预处理24 h组.采用线栓法制备大脑中动脉缺血及缺血再灌注模型,重复夹闭大鼠双侧股动脉4 次(每次10 min,间隔10 min) 作为LIP,采用生化方法测定各组脑组织中丙二醛(MDA)、超氧化物歧化酶(SOD)、三磷酸腺苷(ATP)酶的含量;HE染色观察大鼠脑组织的病理改变.结果 肢体反复短暂缺血预处理组可明显减少MDA的含量,升高SOD活性,增加ATP含量,尤以预处理0 h和6 h组为著,同其余预处理组及对照组相比差异有统计学意义(P<0.05).结论 肢体缺血预处理可提高脑缺血大鼠的SOD活性、降低MDA含量、促进ATP的生成,推知反复短暂的肢体缺血预处理对大鼠脑缺血再灌注损伤有保护作用,它可通过提高脑组织抗氧化酶活性、提高线粒体能量,抑制氧自由基产生及脂质过氧化反应来发挥作用.     

脑温变化对大鼠局灶脑缺血再灌注组织兴奋性氨基酸的影响

目的　研究轻度高温、亚低温对局灶脑缺血组织兴奋性氨基酸 (EAA)的影响。方法　建立大鼠大脑中动脉缺血再灌注线栓模型 ,诱导目标脑温 ,用HPLC荧光法检测脑组织谷氨酸 (Glu)、天冬氨酸 (Asp)、甘氨酸 (Gly)含量。结果　轻度高温组Glu、Asp、Gly明显增高 ;亚低温组则明显降低。结论　轻度高温促进EAA增高 ,在持续增加Glu“兴奋毒性”方面起重要作用 ;亚低温抑制EAA增高 ,在降低Glu“兴奋毒性”方面起重要作用。     

局部亚低温对大鼠局灶脑缺血再灌注后β淀粉样蛋白表达及梗死体积的影响

目的观察病变侧缺血至再灌注期亚低温（32～33℃）对大鼠局灶性脑缺血再灌注后梗死体积和β淀粉样蛋白（β—amyloid protein,Aβ）表达的影响。方法采用改良线栓法建立大鼠大脑中动脉缺血再灌注模型,随机分为假手术组、常温缺血组和亚低温缺血组,两个缺血组各分为5个亚组：分别于缺血后2、3、6、8、12h进行再灌注4h后处死,其中亚低温组于缺血后30min实施病灶侧脑部亚低温并持续至再灌注期。处死大鼠前进行神经功能缺陷评分,TTC染色及运用计算机图像分析技术观察各组大鼠脑梗死体积,采用免疫组织化学法检测Aβ表达,末端脱核苷酸转移酶介导的dUTP缺口末端标记技术（TUNEL）观察神经细胞凋亡情况。结果与常温缺血组比较,亚低温缺血组大鼠脑梗死体积明显减少,Aβ阳性细胞数量明显减少（P〈0．05）,凋亡的神经细胞明显减少（P〈0．05）。神经功能缺陷评分亚低温缺血组明显低于相应时间点常温缺血组（P〈0．05或P〈0．01）。结论病变侧亚低温对脑缺血有保护作用,其机制可能为亚低温抑制Aβ表达,进而抑制神经元凋亡,减少脑梗死体积,促进脑缺血后神经功能恢复。     

亚低温对脑缺血再灌注损伤的保护作用机制

目的探索亚低温对脑缺血再灌注(I/R)损伤的保护作用机制。方法将36只雄性SD大鼠随机分为假手术组、重组组织型纤溶酶原激活剂(rt-PA)组、模型组、I/R+亚低温组、I/R+rt-PA组、I/R+亚低温+rt-PA组,每组各6只。通过构建大鼠的缺血再灌注模型,进行神经功能半定量缺损评分;大鼠血脑屏障渗透实验,比较各组血脑屏障保护作用的差异;免疫组化检测大鼠脑组织中t-PA和组织型纤溶酶原激活物抑制剂(PAI-1)的表达;Western blot检测p-MEK1/2和p-ERK1/2的表达。结果两个亚低温处理大鼠模型组神经损伤情况均低于模型组(P0. 05);亚低温治疗可以降低血脑屏障的通透性; rt-PA组和I/R+rt-PA组大鼠脑组织中t-PA和PAI-1的表达量明显增加,其余各组表达量均较低; rt-PA组和I/R+rt-PA组的p-MEK1/2和p-ERK1/2表达量显著增加,而亚低温处理后可明显降低p-MEK1/2和p-ERK1/2表达量。结论亚低温对脑缺血再灌注损伤的保护作用与降低血脑屏障的通透性、降低大鼠脑组织缺血再灌注后t-PA和PAI-1的表达以及降低p-MEK1/2和p-ERK1/2含量有关。     

Attenuation of focal cerebral ischemic injury in transgenic mice overexpressing CuZn superoxide dismutase.

Oxygen-derived free radicals have been implicated in the pathogenesis of vasogenic edema and infarction caused by ischemia and reperfusion injury. In earlier studies, exogenously supplied liposome-entrapped CuZn superoxide dismutase (CuZn-SOD) ameliorated ischemic brain edema and infarction in rats following focal cerebral ischemia. To ascertain directly the role of SOD in the protection against superoxide radical-induced injury, we measured infarct size and water content 24 hr following focal cerebral ischemia in nontransgenic mice and in transgenic mice bearing the human SOD1 gene. These transgenic mice have 3.1-fold higher cellular CuZn-SOD activity in the brain than do their nontransgenic littermates. We also measured antioxidant levels (reduced glutathione and reduced ascorbate) of contralateral cortex, infarct cortex, surrounding cortex, and striatum. Infarct size and brain edema were significantly decreased in transgenic mice compared with nontransgenic mice. Reduced glutathione and reduced ascorbate levels decreased in the ischemic hemisphere, but levels in surrounding cortex and striatum were significantly higher in transgenic mice than in nontransgenic mice. These results indicate that increased endogenous SOD activity in brain reduces the level of ischemic damage and support the concept that superoxide radicals play an important role in the pathogenesis of infarction and edema following focal cerebral ischemia.     

亚低温通过下调分化抑制因子2保护脑缺血再灌注损伤大鼠

目的 探讨亚低温对脑缺血再灌注大鼠的保护作用以及对分化抑制因子2(inhibitor of differentiation 2,Id2)蛋白表达的影响.方法 72只成年雄性大鼠随机分为假手术组、常温组和亚低温组.应用线栓法制备大脑中动脉闭塞模型,亚低温组给予低温处理[肛温(33±1)℃,鼓膜温度(31±1)℃].分别在缺血再灌注6、12、24和72 h时采用改良神经功能损伤严重程度评分(modified Neurological Severity Score,mNSS)评价神经功能缺损,氯化三苯基四氮唑检测梗死体积,蛋白质印迹法检测缺血皮质Id2表达水平.结果 缺血再灌注6、12、24和72 h时,亚低温组mNSS评分均显著高于常温组,梗死体积均显著小于常温组(P均<0.001).蛋白质印迹分析显示,亚低温组脑缺血再灌注6、12、24和72 h时缺血皮质Id2蛋白表达水平显著低于常温组(P均<0.05).结论 亚低温能减轻脑缺血再灌注后神经功能缺损和缩小梗死体积,其机制可能与下调Id2蛋白表达水平有关.     

Melatonin provides neuroprotection by reducing oxidative stress and HSP70 expression during chronic cerebral hypoperfusion in ovariectomized rats

Abstract:  Oxidative stress is believed to contribute to functional and histopathologic disturbances associated with chronic cerebral hypoperfusion (CCH) in rats. Melatonin has protective effects against cerebral ischemia/reperfusion injury. This effect has mainly been attributed to its antioxidant properties. In the present study, we evaluate the effects of melatonin on chronic cerebral hypoperfused rats and examined its possible influence on oxidative stress, superoxide dismutase (SOD) activity, reduced glutathione (GSH) levels, and heat shock protein (HSP) 70 induction. CCH was induced by permanent bilateral common carotid artery occlusion in ovariectomized female rats. Extensive neuronal loss in the hippocampus at day 14 following CCH was observed. The ischemic changes were preceded by increases in malondialdehyde (MDA) concentration and HSP70 induction as well as reductions in GSH and SOD. Melatonin treatment restored the levels of MDA, SOD, GSH, and HSP70 induction as compared to the ischemic group. Histopathologic analysis confirmed the protective effect of melatonin against CCH-induced morphologic alterations. Taken together, our results document that melatonin provides neuroprotective effects in CCH by attenuating oxidative stress and stress protein expression in neurons. This suggests melatonin may be helpful for the treatment of vascular dementia and cerebrovascular insufficiency.     

Protective effects of ischemic preconditioning on lung ischemia reperfusion injury: an in-vivo rabbit study

BACKGROUND: The goal of this study was to determine the effect of ischemic preconditioning on the extent of normothermic lung ischemia reperfusion injury in rabbits in vivo. METHODS: Thirty male Japanese white rabbits were randomized into two groups. Fifteen rabbits were treated with ischemic preconditioning (their left lung hilus clamped for 10 minutes and released for 15 minutes (group IP)). Fifteen rabbits were not treated with ischemic preconditioning (group C). Then the left lung hilus of both groups were occluded for 60 minutes and reperfused for 60 minutes. Mean arterial pressure, mean pulmonary artery pressure, and core temperature were recorded. Femoral artery blood samples and lung tissue samples were collected after ischemic preconditioning and after 60 minutes of reperfusion. RESULTS: The lung tissue showed little injury after ischemic preconditioning. After 60 minutes of reperfusion, the angiotensin II (A II) and arterial oxygen tension (PaO2) levels in group IP were significantly higher than those in group C, mean pulmonary artery pressure in group IP was significantly lower than that in group C, the wet/dry ratio and malondialdehyde content of lung tissue in group IP was significantly lower than that in group C, the superoxide dismutase contents of lung tissue in group IP was significantly higher than that in group C, and histological findings showed less damage in group IP than in group C. CONCLUSION: Lung ischemic preconditioning could reduce normothermic rabbit lung ischemia-reperfusion injury. The possible mechanisms are increased production of endogenous A II and reduced formation of oxygen free radicals during lung ischemia for 60 minutes followed by reperfusion for 60 minutes.     

Management of temperature during and after cardiac surgery

Neurologic injury is a devastating complication of cardiac surgery. Cerebral cooling is an important aspect of hypothermic cardiopulmonary bypass in some patients, because hypothermia is the only reliable method of neuroprotection against injuries related to cerebral ischemia. Hypothermia may afford neuroprotection by a variety of mechanisms, including reduction in cerebral metabolic rate, decreased excitatory transmitter release, reduced ion influx, and reduced vascular permeability. Conversely, hyperthermia, even if mild (2-3 degrees C), is harmful; it aggravates ischemic neuronal injury and accelerates neuronal death. In patients with acute strokes, hyperthermia worsens prognosis with respect to stroke severity, infarct size, mortality, and outcome in survivors. The degree of temperature discrepancy among standard monitoring sites in individual patients is often striking. The differences between jugular bulb temperature and rectal or bladder temperature are particularly large. Blood temperature in the arterial line leading from the oxygenator may be the most consistently accurate indicator of cerebral temperature. When hypothermia is used to protect vital organs during cardiopulmonary bypass, the cooling phase should be adequate, and the rewarming phase must be carefully managed. Hyperthermia may be as hazardous during the postoperative period as during surgery, exacerbating the extent of tissue injury if an overt stroke has occurred. Postoperative hyperthermia correlates with a greater degree of cognitive dysfunction measured 6 weeks after cardiac surgery. In conclusion, cardiac anesthesiologists can reduce the risk of inadvertent hyperthermia by selecting the best sites for temperature monitoring, carefully controlling the rewarming process, and continuing temperature monitoring during the postoperative period.     

Role of ischemic preconditioning on ischemia-reperfusion injury of the lung.

STUDY OBJECTIVES: Ischemia-reperfusion injury of the lung frequently occurs after cardiopulmonary bypass, after pulmonary thromboembolectomy, and especially during lung transplantation. The protective effects of preconditioning on the heart, liver, bones, and various other organs have been previously evaluated. In this comparative study, we used isolated guinea pig lungs to show the effects of preconditioning on lung ischemia. METHODS: The lungs (n = 10 in each group) were mounted on a modified Langendorff perfusion apparatus and perfused by Krebs-Henseleit solution for 30 min. We applied an ischemic preconditioning (5 min ischemia + 5 min perfusion, two times) in the experimental group. After 3 h of normothermic ischemia, the lungs were reperfused for 30 min. Pulmonary artery pressures and malondialdehyde (MDA) and glutathione (GSH) levels of the tissue and the perfusate were measured before and after the ischemic period and also at the end of reperfusion. Electron microscopic evaluation was done on randomly selected lungs of three animals in each group at the end of the experiment. RESULTS: Both MDA and GSH levels of tissue and perfusate decreased in the experimental group after reperfusion, although the reduction in GSH levels did not reach statistical significance. The increase in pulmonary artery pressure was lower in the preconditioning group after reperfusion. CONCLUSIONS: Our data showed that ischemic preconditioning of the lung may have a protective effect in ischemic-reperfusion injury.