头部贴敷式亚低温对HIBD新生大鼠脑组织线粒体ATP酶活性的影响

目的：研究头部贴敷式亚低温治疗对缺氧缺血脑损伤（hypoxic-ischemic brain damage, HIBD）新生大鼠的脑组织线粒体ATP酶活性的影响,以进一步探讨亚低温对缺氧缺血脑组织的保护机制。方法：将84只Wistar新生鼠随机分为4组：假手术常温对照组、假手术亚低温对照组、HIBD模型常温恢复组、HIBD模型亚低温治疗组。各组动物在HI后不同时间点（2,6,12 h）断头取脑,提取脑组织线粒体并测定其中Na+K+ATP酶和Ca2+ATP酶活性。结果①HIBD常温恢复组及亚低温治疗组在2,6,12 h时Ca2+ATP酶活性均呈下降趋势,分别为3.17±0.81,2.26±0.53,1.31±0.78 μmol/mgPr．h及5.25±0.61,4.59±0.81,4.61±0.62 μmol/mgPr．h,但亚低温治疗各组该酶活性均明显高于相应的常温组（P<0.01）。②HIBD常温及亚低温2 h组Na+K+ATP酶活性较之假手术组无明显改变,6 h、12 h组该酶活性明显低于假手术组,分别为3.76±0.78,3.12±0.53 μmol/mgPr．h及5.25±0.66、 4.74±0.80 μmol/mg Pr．h,但亚低温治疗组明显高于相应常温组（P<0.01）。结论 贴敷式局部亚低温可增加HIBD后脑线粒体ATP酶活性,保护脑组织。［中国当代儿科杂志,2007,9（4）：305-307］     

亚低温减轻新生大鼠缺氧缺血脑细胞凋亡的作用及机制研究

目的：细胞凋亡在新生儿缺氧缺血性脑病(HIE)的发病机制中起重要作用,亚低温治疗是HIE最有前途的治疗方法之一。通过观察缺氧缺血后凋亡通路上关键成分的变化,探讨亚低温减轻新生大鼠脑细胞凋亡的作用及机制。方法：采用7日龄SD清洁级大鼠, 建立新生大鼠HIBD标准模型。模型动物随机分为常温缺氧缺血组 (IN, 肛温=37℃)和亚低温缺氧缺血组 (IH,肛温=33℃)。采用TUNEL结合苏木素-伊红染色、神经元Nissl染色等方法检测脑细胞凋亡;Western blotting加免疫组织化学法观察线粒体及胞浆细胞色素C蛋白改变;分别用RT-PCR和显色底物法检测caspase-3 mRNA表达及其酶活性改变。结果：IN组海马CA1区TUNEL阳性锥体细胞明显增多,DNA电泳梯状条带明显;72 h亚低温治疗显著降低脑细胞凋亡发生率,与常温比较差异有显著性（6.4±1.7 vs 25.3±1.5,P<0.01）。IN组胞浆Cyt c水平6 h开始明显升高,72 h达高峰,而线粒体内Cyt c水平则出现相应的下降;亚低温治疗组胞浆Cyt c水平降低和对应线粒体Cyt c水平的升高,以24 h、48 h和72 h最为明显,与IN组比较差异有显著性（P＜0.05）。HIBD后24 h组结扎侧脑组织caspase-3 mRNA表达明显增加,亚低温治疗显著降低caspase-3 mRNA表达水平,以48 h、72 h 治疗组最明显（P＜0.05）,而caspase-3酶活性却在24 h达高峰,亚低温治疗可明显降低HIBD 后24 h 的caspase-3酶活性,与常温比较差异有显著性（2.42±0.5 RFU vs 34.7±3.2 RFU ,P＜ 0.01)。结论：亚低温治疗能够显著降低HIBD后细胞凋亡发生率,其机制可能作用于凋亡通路的多个部位：减少Cyt c释放,减轻或抑制caspase-3表达及其蛋白酶活性等。［中国当代儿科杂志,2007,9（1）：37-41］     

亚低温对新生猪缺氧缺血脑损伤振幅整合脑电图变化的影响

目的：研究亚低温对新生猪缺氧缺血性脑损伤(HIBD)振幅整合脑电图变化的影响,旨在用振幅整合脑电图这种无创性的检查方法判断亚低温的疗效。方法：34头5 ~7d的新生猪随机分为四组:常温正常组(n= 7)、低温正常组(n= 9)、缺氧缺血(HI)常温组(n= 9)和HI低温组(n= 9)。采用双侧颈总动脉阻断和机械通气吸入6%的氧气制备HIBD模型。HI后2h,低温组采用选择性头部亚低温治疗(维持鼻咽温度35℃±2℃,肛温36. 0℃±2℃)。常温组维持肛温在39℃左右。采用脑功能监测仪连续监测HI及亚低温后不同时间振幅整合脑电图振幅波谱带的变化,分析aEEG各种波形出现的比例。结果：正常新生猪aEEG表现为连续正常电压(CNV),HI24h后HI常温组连续低电压(CLV)、爆发抑制(BS)、平台(FT)比例较缺血前明显增高(P<0. 05),亚低温治疗组CLV、BS、FT比例增高的程度小于HI常温组(P<0. 05),HI后6d亚低温治疗组恢复至CNV的比例大于HI常温组(P<0. 05)。结论：亚低温可明显降低HI后严重aEEG异常波形(CLV, BS和FT)出现的比例,证实亚低温有神经保护作用。     

亚低温干预对缺氧缺血新生鼠脑源性神经营养因子mRNA表达的影响

目的 探讨亚低温对缺氧缺血脑损伤(HIBD)新生大鼠脑源性神经营养因子(BDNF)mRNA表达的影响.方法 新生7日龄Wistar大鼠84只,随机分为:假手术组(n=6),31 ℃亚低温干预组(n=36),非亚低温干预组(对照组,n=36)及正常对照组(n=6).于分组后6、12、24、48、72、96 h用原位杂交技术测定BDNF mRNA.用Tunel染色和免疫组化技术检测神经元凋亡数.结果 HIBD缺血再灌注后脑组织BDNFmRNA表达增加,亚低温组HIBD脑组织BDNFmRNA表达与未干预组比较差异有统计学意义,亚低温组脑组织海马、皮层区细胞凋亡数与未干预组比较差异有统计学意义.结论 亚低温可通过增加HIBD后脑组织海马、皮层BDNFmRNA的表达水平,抑制细胞凋亡而发挥脑保护作用.     

新生大鼠缺氧缺血性脑损伤的亚低温治疗

目的　研究亚低温对缺氧缺血性脑损伤的保护作用 ,探讨亚低温治疗的最佳时机、深度、持续时间。方法　Wistar 7日龄新生大鼠 ,随机分为 :1) 2 9℃低温干预组、34℃低温干预组、常温 (37℃ )恢复组、正常对照组 (假手术组 ) ;2 ) 2 4h低温干预组、4 8h低温干预组、72h低温干预组、常温 (37℃ )恢复组、正常对照组 (假手术组 ) ;3)缺氧缺血后 0min起始低温干预组、6 0min起始低温干预组、12 0min起始低温干预组、6h起始低温干预组、常温 (37℃ )恢复组、正常对照组 (假手术组 )。每组均 2 0只大鼠均于缺氧缺血后 78h处死 ,测定脑组织含水量及微管相关蛋白 2 (MAP 2 )免疫组织化学染色 ,计算脑损伤程度。结果　 1) 2 9℃低温干预效果优于 34℃低温干预效果。 2 ) 72h低温干预效果优于 2 4、4 8h低温干预。 3)缺氧缺血后立即低温干预效果好 ,延迟 6h的低温干预仍有效。结论　缺氧缺血后立即 2 9℃低温干预 72h有显著脑保护作用     

亚低温对新生鼠缺氧缺血性脑损伤神经细胞凋亡和胱天蛋白酶-3活性的影响

目的探讨亚低温对新生鼠缺氧缺血性脑损伤神经细胞凋亡和胱天蛋白酶-3(Caspase-3)活性的影响。方法7日龄SD大鼠分为假手术组、缺氧缺血性脑损伤常温组(HIBD组)和缺氧缺血性脑损伤亚低温处理组(亚低温组)。HIBD组行左颈总动脉结扎后.吸入氧氮混合气持续2h;亚低温组将HIBD新生鼠维持于31-32℃亚低温8h。用TUNEL法和荧光四肽底物(ACDEVDAMC)法分别检测假手术组、HIBD组和亚低温组的凋亡细胞百分率和Caspase-3活性水平。结果与HIBD组比较,亚低温组和假手术组的凋亡细胞百分率和Caspase-3活性水平显著降低。结论亚低温可减弱新生鼠HIBDCaspase-3活性.抑制神经细胞的凋亡。     

缺氧缺血脑损伤时新生大鼠脑皮质神经细胞能量代谢的改变

目的　近年来的一些研究表明 ,线粒体能量代谢异常是新生儿缺氧缺血性脑病 (HIE)发病机制的重要环节之一。该实验研究新生大鼠缺氧缺血性脑损伤 (HIBD)时脑皮质神经细胞内磷酸肌酸 (PCr)、ATP和总腺苷酸池 (ATP +ADP +AMP)的变化。方法　 7日龄Wistar大鼠随机分为假手术对照组 (n =6 )和HIBD组 (n =6 0 )。HIBD组新生鼠分别于缺氧缺血 (HI)后 0 ,2 ,4 ,6 ,8,1 0 ,1 2 ,2 4 ,4 8h和 72h断头 (每个时间点 6只 ) ,取左侧顶枕部脑皮质 ;假手术对照组新生鼠于假手术后 4h断头。用高效液相色谱方法检测脑皮质高能磷酸物质的含量。结果HIBD组新生鼠HI后 0hPCr,ATP和ATP +ADP +AMP即低于正常对照组 (P <0 .0 1或 0 .0 5 ) ,并于缺氧缺血后0～ 6h出现第 1次低谷 ,分别为对照组的 5 1 % ,71 % ,5 0 % ,缺氧缺血后 8～ 1 2h分别恢复到对照组的 92 % ,83%和83% ,与对照组比较差异无显著性 (P >0 .0 5 ) ;以后又下降到低于正常对照组 (P <0 .0 1 ) ,并于缺氧缺血后 2 4～4 8h下降到第 2次低谷 ,分别为对照组的 5 8% ,6 1 %和 32 %。结论　新生大鼠HIBD后 2 4～ 4 8h皮质神经细胞出现第 2次能量代谢衰竭 ,能量代谢变化可作为判断缺氧缺血性脑损伤干预手段是否有效的观察指标。     

亚低温对新生鼠缺氧缺血性脑损伤自由基影响的研究

目的　 研究亚低温对新生鼠缺氧缺血性脑损伤后自由基的影响。 方法 　 7日龄大鼠行左侧颈总动脉结扎后吸入8%氧气 2h ,制成缺氧缺血性脑损伤模型。动物随机分成五组 :假手术组、缺氧缺血组、缺氧缺血后 30min给予亚低温组、缺氧缺血后 1h给予亚低温组、缺氧缺血后 3h给予亚低温组。脑皮质细胞匀浆用于测定丙二醛 (MDA)含量和超氧化物歧化酶 (SOD)活性。 结果 　缺氧缺血组MDA含量明显高于假手术组 ,而亚低温各组MDA含量均低于缺氧缺血组 ,而且亚低温应用越早者MDA含量减少越明显。 结论 　亚低温可以通过减少自由基的产生发挥对缺氧缺血性脑损伤的保护作用     

低温治疗新生大鼠缺氧缺血性脑损伤起始时间的探讨

目的 探讨低温干预起始时间对新生大鼠缺氧缺血性脑损伤的影响。方法 Wistar 7日龄新生大鼠,随机分到:缺氧缺血后0 min、60 min、120 min、6 h起始亚低温干预组、常温(37℃)恢复组、正常对照组(假结扎组),每组30只。每组20只于缺氧缺血后78 h处死,10只用于测定脑组织含水量,10只经灌注固定,冠状切片进行微管相关蛋白-2(MAP-2)免疫组化染色,测定脑梗塞面积;另外10只于生后42d用迷宫实验检测其学习和记忆能力。结果 (1)亚低温干预各组大鼠脑组织含水量与常温恢复组相比显著减少(P<0.05);(2)亚低温干预各组大鼠脑梗塞面积与常温恢复组相比显著降低(P<0.05),且随着亚低温干预起始时间的延迟,梗塞面积逐渐增大;延迟6 h的干预仍有效;(3)亚低温干预各组大鼠学习和记忆能力显著高于常温恢复组(P<0.05)。结论亚低温干预效果与缺氧缺血后低温的起始时间有关,延迟6 h的亚低温干预仍有效。     

雄激素对新生大鼠缺氧缺血脑损伤的保护作用及机制研究(英文)

目的：雄激素对缺氧缺血后脑损伤有神经保护作用,但其作用机制尚不完全清楚。该研究探讨雄激素对缺氧缺血性脑损伤(HIBD)的保护作用及其可能的机制。方法：64只7日龄SD大鼠随机分为假手术组、HIBD对照组和雄激素干预组。通过结扎左颈总动脉和吸入8%氧气和92%氮气的混合气体制备新生鼠HIBD模型。假手术组仅做颈正中切口,游离左颈总动脉,不结扎,不行低氧处理。雄激素干预组在模型制成后即刻注射丙酸睾丸酮(25mg/kg)。缺氧缺血(HI)后6h、24h、72h、7d取脑组织制作石蜡切片,用免疫组化法观察Bcl-2和Bax蛋白在各组大鼠皮质和海马表达的动态变化。HI后6h、24h、48h断头取脑制作脑匀浆,测定SOD活性和MDA含量。结果：假手术组大鼠左脑的皮质及海马可见少量Bcl-2蛋白和Bax蛋白免疫阳性细胞表达,与HIBD对照组和雄激素干预组比较差异均有显著性意义(P<0.01)。雄激素干预组HI后6h、24h、72hBcl-2蛋白在皮层和海马的表达水平明显高于HIBD对照组(P<0.05或0.01)。雄激素干预组Bax蛋白的表达水平在HI后24h显著低于HIBD对照组(P<0.05),其他时间点两组Bax蛋白的表达无明显差别。与假手术组比较,HIBD对照组HI后6h大鼠脑组织中SOD活性明显降低,MDA含量明显增加(P<0.05)。HIBD对照组HI后24hSOD活性降至最低值,MDA含量升至最高。雄激素干预增加了SOD活性,雄激素干预组HI后6h、24h、48hSOD活性均明显高于HIBD对照组,差异有显著性意义(P<0.05或0.01)。雄激素干预亦导致了脑组织中MDA含量降低,雄激素干预组HI后6h、24hMDA含量均明显低于HIBD对照组,差异有显著性意义(分别P<0.05、P<0.01)。结论：雄激素发挥脑保护作用可能通过上调Bcl-2蛋白、下调Bax蛋白表达以及通过减少抗氧化剂的消耗和抑制氧自由基的生成,从而减轻缺氧缺血后神经细胞的损伤。     

A limited interval of delayed modest hypothermia for ischemic brain resuscitation is not beneficial in neonatal swine.

This investigation determined if a short interval of modest hypothermia (1 h) initiated 30 min after brain ischemia provided neuroprotection. The rationale for the time and duration of brain cooling reflects the likelihood that the implementation of neuroprotective strategies will occur at an interval shortly after ischemia, and that long-term maintenance of normothermia is a cornerstone of neonatal stabilization. Studies were performed in 22 ventilated neonatal mini-swine in a superconducting magnet to obtain 31P magnetic resonance spectra. After a control period all animals underwent 15 min of global brain ischemia and were maintained normothermic for the first 30 min post-ischemia. In one group of 11 swine normothermia was continued. In the other group of 11 swine, modest hypothermia was initiated at 30 min post-ischemia, continued for 1 h and followed by resumption of normothermia. Animals were subsequently weaned from ventiltor support, removed from the magnet, and underwent neurobehavioral and histologic assessment at 72 h post-ischemia. Both groups had similar severity of ischemia, as indicated by identical changes in arterial blood pressure and pH, alterations in brain beta-nucleotide triphosphate (% of control where control = 100%, 32 +/- 28 vs 27 +/- 26% for normothermic and hypothermic groups, respectively), and the extent of intraischemic brain acidosis (6.13 +/- 0.19 vs 6.14 +/- 0.14 for normothermic and hypothermic groups, respectively). In both groups the distribution of stages of encephalopathy were the same: 1 normal and 10 abnormal (4 mild, 2 moderate, and 4 severe) normothermic, and, 3 normal and 8 abnormal (4 mild, 2 moderate, and 2 severe) hypothermic animals. There was no difference in the extent of neuronal injury between groups. We conclude that a 1-h interval of modest hypothermia initiated at 30 min post-ischemia does not confer neuroprotection.     

Early head cooling in newborn piglets is neuroprotective even in the absence of profound systemic hypothermia

BACKGROUND: Selective head cooling in the newborn infant has been proposed as a neuroprotective treatment with a lower level of systemic adverse effect than that of systemic hypothermia. However, the efficacy is not confirmed as well as that of systemic hypothermia. In order to analyze the safety and efficacy of selective head cooling, 25 newborn piglets were randomly selected for either normothermic or hypothermic treatment. METHODS: Global hypoxic insult was induced by lowering the oxygen concentration to the maximal level to maintain the background electroencephalogram (EEG) voltage under 7 microV for 45 min. The core temperature of normothermic piglets was maintained between 38.5 degrees C and 39 degrees C, while prophylactic cooling was applied to the hypothermic piglets at the same time of the insult. Very mild systemic hypothermia by 1 degrees C was induced in addition to selective head cooling with 10 degrees C coolant temperature. Animals were killed for histopathological examination seven hours after the end of the insult. RESULTS: Two normothermic piglets died while all hypothermic piglets survived. Neuropathological findings were significantly severer in the normothermic group than in the hypothermic group. Intracranial pressure was significantly lower, and EEG recovery was significantly better in the hypothermic piglets. There was no significant difference in the lowest oxygen concentration, degrees of acidosis, blood lactate, and blood pressure between the groups, although heart rate was significantly lower in the hypothermic group. CONCLUSIONS: We have demonstrated that early head cooling was effective in preventing some of the earliest brain damage due to hypoxic insult even in the absence of profound systemic hypothermia.     

亚低温对HIBD新生鼠大脑皮质神经元NSE表达及血糖水平影响的研究

目的：通过亚低温对新生鼠缺氧缺血脑损伤(HIBD)大脑皮质神经元特异性烯醇化酶(NSE)及血糖水平影响的研究,探讨亚低温对HIBD的保护作用机制。方法：建立新生鼠HIBD标准化动物模型,将其随机分为对照组、31℃亚低温和34℃亚低温干预组及假手术组,应用免疫组化染色观察大脑皮质区NSE阳性神经元数目,并利用微量血糖监测仪测定血糖。结果：缺血缺氧后12 h,24 h亚低温干预组大脑皮质NSE阳性神经元数目均显著低于对照组［31℃亚低温组：(54.3±6.5) vs (82.3±6.0),(34.6±5.6) vs (53.3±5.6),P<0.05 或 0.01;34℃亚低温组：(56.8±7.1) vs (82.3±6.0),(32.9±4.9) vs (53.3±5.6),P<0.05］。缺氧缺血后12 h,24 h 血糖水平［31℃亚低温组：(5.74±1.52),(5.89±1.62) mmol/L;34℃亚低温组：(5.69±1.48),(5.91±1.53) mmol/L］亦显著高于对照组［(3.64±1.22),(4.16±1.54) mmol/L］(P<0.01)。31℃亚低温和34℃亚低温干预两组间各个时期大脑皮质区NSE阳性神经元数目及血糖水平差异无显著性(P>0.05)。结论：亚低温可通过抑制神经元内NSE活性及升高血糖水平,对HIBD新生鼠大脑皮质神经细胞起到保护作用。     

Hypothermia for 24 hours after asphyxic cardiac arrest in piglets provides striatal neuroprotection that is sustained 10 days after rewarming

The neuroprotective effect of hypothermia instituted after resuscitation from asphyxic cardiac arrest has not been studied in immature brain, particularly in a large animal model with recovery periods greater than 4 d. Moreover, protection from severe hypoxia seen with 3 h of hypothermia was reported to be lost when hypothermic duration was extended to 24 h in unsedated piglets, in contrast to the neuroprotection reported by 72 h of intrauterine head cooling in fetal sheep. Piglets (5-7 postnatal days) were subjected to asphyxic cardiac arrest followed by 24 h of either hypothermia (34 degrees C) or normothermia (38.5-39 degrees C). Comparisons were made with normothermic and hypothermic surgical sham animals without asphyxia. All of these groups were sedated, paralyzed, and mechanically ventilated for the first 24 h to prevent shivering and possible depletion of glucose stores. Hypothermia per se did not cause remarkable structural abnormalities. Ischemic damage was evaluated in putamen at 1 d of recovery without rewarming and at 11 d (10 d +/- SD after rewarming). Ischemic cytopathology affected 60 +/- 12% of neurons in putamen of normothermic animals compared with 9 +/- 6% in hypothermic animals at 1 d of recovery without rewarming. At 11 d of recovery from hypoxia-ischemia, the density of viable neurons (neuron profiles/mm2) in putamen was markedly reduced in normothermic animals (81 +/- 40) compared with hypothermic animals (287 +/- 22), which was the same as in sham normothermic (271 +/- 21), sham hypothermic (288 +/- 46) and na?ve animals (307 +/- 51). These data demonstrate that 24 h of hypothermia at 34 degrees C with sedation and muscle relaxation after asphyxic cardiac arrest prevents necrotic striatal neuronal cell death in immature brain before rewarming, and that the effect is sustained at 11 d after injury without deleterious side effects.     

Effect of hypothermic post-treatment on hypoxic-ischemic striatal injury, and normal striatal development, in neonatal rats: a stereological study

Fundamental questions remain about the optimal temperature, duration, and mode of delivery that provide the best striatal neuroprotection from hypothermia after perinatal hypoxia-ischemia. This study used stereological methods to investigate whether a mild (i.e. 2 degrees C) or a moderate (5 degrees C) decrease in whole body temperature, for 6 h immediately postinsult, was neuroprotective for striatal medium-spiny neurons after perinatal hypoxia-ischemia in the rat. This study also investigated whether moderate hypothermia had any effect on normal striatal development. Hypoxia-ischemia or sham hypoxia-ischemia was induced on postnatal day (PN) 7. Pups were kept either normothermic, mildly hypothermic, or moderately hypothermic for 6 h immediately postinsult. The absolute number of striatal medium-spiny neurons was calculated using modern stereological methods. There was no significant difference in the absolute number of medium-spiny neurons in the right striatum after either mild hypothermia or moderate hypothermia. There was also no significant difference in the absolute number of medium-spiny neurons between the control normothermic and the control moderately hypothermic pups. The latter results suggest that moderate hypothermia for 6 h immediately postinsult may be a safe treatment for striatal medium-spiny neurons. Yet, neither mild nor moderate hypothermia alone for 6 h immediately posthypoxia-ischemia is neuroprotective for striatal medium-spiny neurons.     

Cardiac output,pulmonary artery pressure,and patent ductus arteriosus during therapeutic cooling after global hypoxia-ischaemia

OBJECTIVE: To assess by Doppler echocardiography the effects of 24 hours of whole body mild hypothermia compared with normothermia on cardiac output (CO), pulmonary artery pressure (PAP), and the presence of a persistent ductus arteriosus (PDA) after a global hypoxic-ischaemic insult in unsedated newborn animals. DESIGN: Thirty five pigs (mean (SD) age 26.6 (12.1) hours and weight 1.6 (0.3) kg) were anaesthetised with halothane, mechanically ventilated, and subjected to a 45 minute global hypoxic-ischaemic insult. At the end of hypoxia, halothane was stopped; the pigs were randomised to either normathermia (39 degrees C) or hypothermia (35 degrees C) for 24 hours. Rewarming was carried out for 24-30 hours followed by 42 hours of normothermia. Unanaesthetised pigs were examined with a VingMed CFM 750 ultrasound scanner before and 3, 24, 30, and 48 hours after the hypoxic-ischaemic insult. Aortic valve diameter, forward peak flow velocities across the four valves, and the occurrence of a PDA were measured. Tricuspid regurgitation (TR) velocity was used to estimate the PAP. Stroke volume was calculated from the aortic flow. RESULTS: Twelve animals (seven normothermic, five hypothermic) had a PDA on one or more examinations, which showed no association with cooling or severity of insult. There were no differences in stroke volume or TR velocity between the hypothermic and normothermic animals at any time point after the insult. CO was, however, 45% lower at the end of cooling in the subgroup of hypothermic pigs that had received a severe insult compared with the pigs with mild and moderate insults. CO and TR velocity were transiently increased three hours after the insult: 0.38 (0.08) v 0.42 (0.08) litres/min/kg (p = 0.007) for CO; 3.0 (0.42) v 3.4 (0.43) m/s (p < 0.0001) for TR velocity (values are mean (SD)). CONCLUSIONS: The introduction of mild hypothermia while the pigs were unsedated did not affect the incidence of PDA nor did it lead to any changes in MABP or PAP. Stroke volume was also unaffected by temperature, but hypothermic piglets subjected to a severe hypoxic-ischaemic insult had reduced CO because the heart rate was lower. Global hypoxia-ischaemia leads to similar transient increases in CO and estimated PAP in unsedated normothermic and hypothermic pigs. There were no signs of metabolic compromise in any subgroup, suggesting that 24 hours of mild hypothermia had no adverse cardiovascular effect.     

实验性缺氧缺血新生猪脑线粒体DNA损伤的研究

目的：观察实验性缺氧缺血后新生猪不同时段脑线粒体DNA8003bp损伤,探讨缺氧缺血性脑损伤(hypoxicischemicbraindamage,HIBD)能量代谢障碍的分子生物学基础。方法：将3日龄新生猪(n=50)随机分为对照组和HIBD实验0,24,48,72h组。实验组结扎左侧颈总动脉并置于8%氧气2h制作HIBD动物模型,对照组行假手术。取各组动物左侧大脑海马区皮质提取脑线粒体DNA(mitochondrialDNA,mtDNA),LXPCR方法扩增检测200bp及8003bpmtDNA片段。PCR产物行琼脂糖凝胶电泳,结果以积分光密度(IOD)值表示。结果：8003bp片段缺氧缺血后0hIOD值22.616±2.276较对照组56.995±0.317显著降低(P<0.05),24h时IOD值为27.719±0.309和48h为49.491±3.233,有所恢复,仍低于对照组(P<0.05),72h时IOD值为55.972±2.236与对照组相比无统计学差异(P>0.05)。结论：缺氧缺血后新生猪脑海马区神经元mtDNA发生断裂性损伤,72h恢复至正常水平。缺氧缺血性mtDNA损伤可能与缺氧缺血情况下线粒体呼吸链复合物活性下降及迟发性神经元死亡有关。