持续高氧对新生鼠肺组织一氧化氮、一氧化氮合酶及病理学的动态影响

目的探讨持续吸入高氧后新生大鼠肺组织一氧化氮(NO)含量、一氧化氮合酶(NOS)活力的动态变化及病理学改变。方法足月新生鼠生后12h内分别持续吸入90%±5%的高氧和空气,于1、3、7、14、21d,分别检测肺组织NO含量、NOS活性以及动态观察病理改变。结果(1)NO含量:在7、14和21d,高氧组水平高于空气组,数值分别为(99.38±7.80)vs(88.78±8.00),P<0.05;(128.18±33.78)vs(93.30±16.73),P<0.05;(170.66±34.00)vs(106.37±25.11),P<0.01。(2)NOS活力:在高氧暴露3d时高于空气组,(20.56±2.56)vs(18.25±0.71),P<0.05;并持续至21d,数值分别为(24.09±2.48)vs(21.10±2.38),P<0.05;(25.07±2.06)vs(20.27±4.15),P<0.05;(27.06±4.79)vs(20.45±2.53),P<0.01。(3)病理学:吸高氧3d时炎症反应为主,7d时炎症反应更明显,开始出现肺间隔增宽,肺泡发育受阻,14d和21d间质增生、肺泡化降低越来越明显。结论持续吸入高氧可致新生鼠发生与人类BPD有类似的病理改变;肺组织病理损伤逐渐加重时,肺组织NO含量和NOS活性增加,提示NO可能在BPD中有重要作用。     

慢性肺疾病早产鼠的肺组织中HoxB5 mRNA表达及其对肺发育的影响

目的 探讨高氧致慢性肺疾病(CLD)早产鼠的肺组织HoxB5基因表达规律及其对肺发育抑制的影响机制.方法 将孕21 d剖宫取出的新生鼠(即早产鼠)80只随机分为实验组及对照组(每组均为40只),采用高浓度氧诱导早产鼠CLD模型,分别于实验后1、3、7、14、21 d采集肺组织,应用反转录聚合酶链反应(RT-PCR)等技术,测定肺组织HoxB5、AQP-5、SP-B mRNA水平,并同期观察肺发育的评价指标放射状肺泡计数(RAC)的变化.结果 生后1 d和3 d,实验组和对照组的HoxB5、AQP-5及SP-B mRNA水平和RAC均差异无统计学意义(P＞0.05);生后7 d,与对照组比较,实验组RAC开始减少(6.35±0.83vs.7.67 ±0.52),HoxB5(0.98±0.14vs.1.20±0.16)及AQP-5(0.78±0.11vs1.04±0.19)mRNA也明显降低(P＜0.05)、SP-B(1.34±0.04vs1.04±0.11)反而明显升高(P＜0.05);生后14 d,实验组RAC逐渐减少,HoxB5及AQP-5 mRNA持续下降,21 d,HoxB5(0.64±0.11vs.1.18±0.13)及AQP-5(0.67±0.12vs.0.97±0.01)mRNA降至最低(P＜0.01),而SP-B(1.43±0.07vs.1.12±0.09)mRNA升至最高(P＜0.01);实验组肺组织HoxB5 mRNA水平及RAC呈明显正相关(γ=0.685,P＜0.01).结论 暴露高氧中早产鼠的肺组织HoxB5基因呈低水平表达,其表达降低可能导致的Ⅱ型肺泡上皮细胞向Ⅰ型肺泡上皮细胞的分化障碍与CLD肺发育停滞密切相关.     

地塞米松对高氧肺损伤新生大鼠肺水通道蛋白1表达的影响

目的 探讨地塞米松对新生大鼠高氧肺损伤时水通道蛋白1(AQP1)表达的影响及其对肺损伤的可能保护机制.方法 新生Wistar大鼠32只随机分为空气组、高氧组、空气+地塞米松组、高氧+地塞米松组.第3天取肺组织,采用逆转录-聚合酶链反应(RT-PCR)和免疫组织化学法检测AQP1的mRNA表达和分布变化;并对肺湿/干重比(W/D)、支气管肺泡灌洗液(BALF)中的蛋白含量、肺通透指数及组织病理学改变进行对比分析.结果 高氧暴露第3天肺组织出现出血、炎性细胞浸润和水肿,肺W/D、BALF蛋白含量、肺通透指数明显升高;地塞米松干预组肺损伤程度减轻,测定值降低.空气组、高氧组、高氧+地塞米松组AQP1 mRNA相对吸光度比值分别为0.70±0.04、0.42±0.03、1.04±0.04,各组间差异有显著性(P<0.05);与空气组相比,高氧组AQP1 mRNA表达明显降低,高氧+地塞米松组AQP1 mRNA表达显著上调;AQP1蛋白表达与其mRNA变化一致.结论 高氧肺损伤时大鼠肺AQP1表达下调;地塞米松干预对肺损伤有保护作用,上调肺AQP1的表达可能是其作用机制之一.     

U74389G对高氧暴露新生大鼠肺内巨噬细胞聚集和肺发育的影响

目的观察抗氧化剂-U74389G对高氧暴露新生大鼠肺内自由基产物、巨噬细胞聚集、硝基酪氨酸形成以及肺细胞增殖活性的影响,研究高氧性肺损伤发生机制及各种介质的相互关系,探讨抗氧化干预的作用.方法采用Sprague Dawley新生大鼠95%O2暴露7 d建立急性高氧肺损伤模型.应用气相色谱-质谱联用技术测定肺组织羟自由基,酶联免疫法测定脂质过氧化产物8-异前列腺烷,免疫组织化学法测定肺内巨噬细胞聚集和硝基化酪氨酸形成,3H-TdR掺入法(放射自显影)测定肺细胞增殖状况.结果 95%高浓度氧暴露可致新生大鼠严重肺损伤,肺组织羟自由基(2,3-DHBA与2,5-DHBA分别为 49.2±3.5 pmol/mg、55.8±2.3 pmol/mg)及脂质过氧化产物(8-异前列腺烷含量为546.6±32.2 pg/mg) 与空气对照组比较均显著增加 (P＜0.05),肺内巨噬细胞聚集明显,蛋白质酪氨酸发生显著硝基化,肺上皮细胞增殖停滞.抗氧化剂U74389G可降低肺组织自由基及其衍生物产生(2,3-DHBA、2,5-DHBA与8-异前列腺烷水平分别为37.9±2.4 pmol/mg、31.3±1.9 pmol/mg和358.5±24.1 pg/mg,P＜0.05),减少巨噬细胞聚集和蛋白质硝基化,肺上皮细胞增殖部分恢复,但未能显著改善高氧所致的肺实质病理形态学变化,且对正常肺细胞增殖有一定影响.结论高氧暴露通过增加肺内自由基产物及炎性细胞浸润等机制导致肺损伤,抗氧化干预可抑制或阻断其过程而具有治疗应用前景,但应充分考虑抗氧化对正常细胞增殖分化的影响.     

外源性抗转化生长因子-β1抗体对新生大鼠高浓度氧致肺纤维化的影响

目的 观察不同剂量的外源性抗转化生长因子-β1（TGF-β1）抗体作用下，TGF -β1在新生SD大鼠高浓度氧（高氧，>95%O2）致肺纤维化中的表达，了解不同剂量的外源性抗TGF -β1抗体在高氧致肺纤维化中的作用。方法 将120只足月新生SD大鼠随机分为6组：空气对照组（Ⅰ组），高氧组（Ⅱ组），高氧+抗TGF -β1抗体 0.1 mg·kg-1组（Ⅲ组），高氧+抗TGF -β1抗体 0.2 mg·kg-1组（Ⅳ组），高氧+抗TGF -β1抗体 0.4 mg·kg-1组（Ⅴ组），高氧+抗TGF -β1抗体 0.8 mg·kg1组（Ⅵ组），每组20只。观察及检测高氧暴露3、7、14和28 d各组大鼠肺组织病理改变以及TGF -β1免疫组化染色。结果 Ⅱ、Ⅲ、Ⅳ组3和7 d时表现为明显的急性炎症改变，肺组织水肿、渗出、出血和肺泡间隔轻度增厚，14 d时急性炎症减轻，而肺组织中TGF -β1表达呈强阳性；28 d时出现明显的胶原沉积，形成纤维化。Ⅴ、Ⅵ组3、7、14和28 d时相点TGF -β1的表达明显减弱，与Ⅰ组差异无统计学意义；病理改变示早期有轻度炎症反应， 14和28 d无明显成纤维细胞增生及胶原生成，未形成肺纤维化。结论 新生SD大鼠连续吸入高氧后可导致急、慢性肺损伤。高氧暴露可刺激肺部产生过量的TGF -β1，TGF -β1是与纤维化关系最密切的TGF-β亚型，可促进成纤维细胞分化、生长和增殖。高氧暴露时给予适当剂量外源性抗TGF -β1抗体可减轻新生SD大鼠急性肺损伤，从而减轻肺纤维化。应用外源性抗TGF -β1抗体干预对高氧致肺纤维化损伤有保护作用。     

Prominent white matter lesions develop in Mongolian gerbils treated with 100% normobaric oxygen after global brain ischemia

Summary Carotid arteries were occluded bilaterally for 15 min in two groups of Mongolian gerbils. The first group received 100% oxygen during the first 3 h of reperfusion. During that period, room air was given to the second group. After 3 h, both groups received room air. Brains of gerbils that died within 14 days after occlusion were removed, fixed in formalin and embedded in paraffin. Gerbils that survived 15–28 days were perfused with formalin before their brains were removed and embedded in paraffin. Adjacent, serially cut sections were stained with luxol fast blue (LFB)-H&E, cresyl violet, according to the Bodian method, or immunocytochemically with antisera raised against myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP). In brain sections of gerbils receiving 3 h of 100% oxygen, there were circumscribed white matter lesions in the corpus striatum, lateral thalamus, mesencephalon and posterior limb of the internal capsule. Myelin sheaths were swollen, fragmented and were less intensely stained by MBP antiserum. MBP and LFB-stained myelin fragments were present extracellularly and in macrophages. Many axons in these areas appeared undamaged. Previously described ischemic changes were found in gray matter and some areas of white matter in both groups. However, neurons in the deeper laminae of the cerebral cortex appeared to be better preserved in gerbils given oxygen. The results suggest that hyperoxia, if present immediately after transient brain ischemia, may damage myelin more severely than other cellular elements.     

Oxygen free radicals and lungs

Some of the metabolites resulting from the monovalent reduction of O₂, superoxide anion and hydroxyl radical, are O₂ radicals, whereas H₂O₂, which is not a radical since having no unpaired electron, is also an active O₂ intermediate. These O₂ metabolites are formed intracellularly as a result of normal metabolism. Their production can increase following exposure to high O₂ concentration, radiations or certain drugs. An increased amount of extracellular O₂ metabolites occurs after activation of certain inflammatory cells or during the course of the hypoxanthine-xanthine oxidase reaction. To counteract this oxidative stress, antioxidant defenses exist, whether enzymatic (superoxide dismutase, glutathione peroxidase, catalase, etc.) or nonenzymatic (GSH, vitamin E and C, etc.). Oxidative injury can result from an imbalance between oxidative stress and the defense mechanisms. The main targets are protein, DNA and lipids. The cellular response of the lung is stereotyped and involves cell injury (especially endothelial c cells and type I pneumocytes), inflammatory reaction and repair processes.     

氨溴索对高氧肺损伤的保护作用

目的观察氨溴索对高氧肺损伤的保护作用。方法将63例长时间吸氧的新生儿随机分为两组,对照组32例,给予常规治疗;观察组31例,在常规治疗的基础上加用氨溴索。结果观察组发生支气管肺发育不良等肺损伤并发症1例占3.2%,对照组7例占21.9%,两组比较差异有统计学意义(χ2=4.45,P<0.05),平均吸氧时间和机械通气时间观察组分别为(9.1±5.9)d和(3.0±0.8)d,对照组为(12.9±7.1)d和(3.0±12.2)d,两组比较,t分别为,P均<0.05,有显著性差异,观察组优于对照组。结论氨溴索可以减轻高氧引起的肺损伤,减少吸氧和机械通气的时间。     

Thioredoxin-1 protects against hyperoxia-induced apoptosis in cells of the alveolar walls

BACKGROUND: The mechanisms of hyperoxia-induced lung injury remain poorly defined. Thioredoxin-1 (TRX-1) is a small ubiquitous protein that acts as an important radical scavenger. We investigated the effect of TRX-1 on apoptosis in hyperoxia-induced lung injury. METHODS: Mice were exposed to 98% O(2) to produce a model of hyperoxia-induced lung injury. Using transgenic mice overexpressing human TRX-1 (hTRX-1), we assessed lung structure (n=4 per group), immunohistochemical staining for 8-hydroxy-deoxyguanosine (n=4 per group), TUNEL staining (n=5 per group), cytokine (n=5 per group) of IL-1beta and IL-6, and protein (n=6 per group) and m-RNA levels (n=4 per group) (or both) of cytochrome c, Bcl-2, Bax, p21, and p53 in the lungs. RESULTS: After exposure to hyperoxia, hTRX-1 transgenic mice had significantly decreased alveolar damage. The apoptotic index was significantly lower in hTRX-1 transgenic mice than in wild-type (WT) mice after exposure to hyperoxia. Protein expression of cytochrome c in the lung was significantly lower in hTRX-1 transgenic mice than in WT mice after exposure to hyperoxia. Protein expression and m-RNA levels of Bcl-2 in the lung were significantly higher in hTRX-1 transgenic mice than in WT mice after exposure to hyperoxia. TRX-1 had no effect on the protein and m-RNA levels of Bax and p21. The protein and m-RNA levels of p53 was unaffected by hyperoxia in hTRX-1 transgenic mice. The cytokine level of IL-6 was significantly higher in hTRX-1 transgenic mice than in WT mice after exposure to hyperoxia. TRX-1 had no effect on cytokine level of IL-1beta. CONCLUSIONS: These findings suggest that overexpression of hTRX-1 protects against hyperoxia-induced apoptosis in cells of the alveolar walls. The up-regulating Bcl-2 protein is considered to be one of antiapoptotic effects of TRX-1 in hyperoxia-induced lung injury.     

前列腺素E1在高氧肺损伤中的保护作用

目的：研究前列腺素El对高氧诱导的急性肺损伤是否有保护作用。方法：40只雄性SD大鼠被随机分成四组。分别予腹腔注射生理盐水或前列腺素El(PGEl)后暴露于21％O2或95％O272h，分别测定支气管肺泡灌洗液(BALF)中的总蛋白(TP)、乳酸脱氢酶(LDH)、粒细胞数及血清总蛋白，并作肺组织形态学观察。结果：PGEl腹腔注射组暴露于高氧后BALF中的TP，LDH及粒细胞数量较使用生理盐水的高氧暴露组显著下降，而血清总蛋白无显著性差异。肺组织石蜡包埋切片HE染色，光镜下观察高氧暴露组肺组织水肿。结论：高氧可诱导急性肺损伤：PGEl对高氧诱导的肺损伤有保护作用。