Oxygen radicals generated at reflow induce peroxidation of membrane lipids in reperfused hearts.

To test whether generation of oxygen radicals during postischemic reperfusion might promote peroxidation of cardiac membrane lipids, four groups of Langendorff-perfused rabbit hearts were processed at the end of (a) control perfusion, (b) 30 min of total global ischemia at 37 degrees C without reperfusion, (c) 30 min of ischemia followed by reperfusion with standard perfusate, (d) 30 min of ischemia followed by reperfusion with the oxygen radical scavenger human recombinant superoxide dismutase (h-SOD). The left ventricle was homogenized and tissue content of malonyldialdehyde (MDA), an end product of lipid peroxidation, was measured on the whole homogenate as well as on various subcellular fractions. Reperfusion was accompanied by a significant increase in MDA content of the whole homogenate and of the fraction enriched in mitochondria and lysosomes. This phenomenon was not observed in hearts subjected to ischemia but not reperfused, and was similarly absent in those hearts which received h-SOD at reflow. Reperfused hearts also had significantly greater levels of conjugated dienes (another marker of lipid peroxidation) in the mitochondrial-lysosomal fraction. Again, this phenomenon did not occur in ischemic hearts or in reperfused hearts treated with h-SOD. Unlike the effect on tissue MDA and conjugated dienes, reperfusion did not significantly stimulate release of MDA in the cardiac effluent. Treatment with h-SOD was also associated with significant improvement in the recovery of cardiac function. In conclusion, these data directly demonstrate that postischemic reperfusion results in enhanced lipid peroxidation of cardiac membranes, which can be blocked by h-SOD, and therefore is most likely secondary to oxygen radical generation at reflow.     

依达拉奉对家兔失血性休克缺血-再灌注损伤的保护作用

目的 观察兔失血性休克再灌注过程中血浆丙二醛(MDA)、一氧化氮(NO)与超氧化物岐化酶(SOD)水平的动态变化,以及肺脏、肾脏病理改变;并探讨依达拉奉的保护作用.方法 29只家兔全身肝素化后随机分为三组:假手术组(C组,n=7)、失血性休克再灌注组(I/R组,n = 10)和依达拉奉保护组(L/R-edaravone组,n=12).后两组制作失血性休克再灌注模型,在10 min内通过左股动脉放血,维持平均动脉压(MAP)40 mmHg达到60 min.I/R-edar-avone组静脉应用依达拉奉.然后开始复苏,要求在60 min内回输全部失血和等量生理盐水,使MAP维持在失血前70%以上.休克后10 h L/R-edaravone组静脉再次应用依达拉奉.在复苏后20 h处死所有家兔,同时取所有兔的右肺部分组织和右肾部分组织作病理检查.分别测休克前、休克1 h、再灌注后1 h、5 h及20 h血浆MDA、SOD、NO含量.结果 休克前三组动物血浆MDA、NO及SOD含量均无显著统计学差异.休克后I/R组家兔血浆MOA(5.35±0.29)μmol/L及NO(27.75±2.88) μmol/L水平均较C组的[(4.44±0.59)μmol/L,(25.01±4.95) μmol/L]要高,而I/R组的SOD水平(194.58±14.42)U/ml 较C组(210.86±24.54)U/ml要低(P均<0.01).复苏后20 h这些变化更加明显,I/R组MDA和NO水平持续增加[(5.69±0.24)μmol/L,(28.01±3.10)μmol/L,P<0.05],而SOD水平继续下降[(151.83±9.36)U/ml,P<0.05].与I/R组比较,I/R-edaravone组的MDA水平显著降低[(3.48±0.23) μmol/L,P<0.01],SOD水平明显升高[(195.10±11.87)U/ml,P<0.01].病理检查提示依达拉奉可以减轻肺脏和肾脏病理损害.结论 依达拉奉通过清除自由基,有效减轻失血性休克再灌注过程中重要脏器的损害.     

血液稀释和缺血预处理对猪心脏缺血再灌注损伤的保护作用

目的在猪心肌缺血再灌注模型上,观察等容血液稀释和缺血预处理对再灌注损伤心肌的保护作用. 方法 18头小型猪建立急性心肌缺血模型,随机分为 3组对照组 (组Ⅰ, n=6),缺血预处理组 (组Ⅱ, n=6),缺血预处理加血液稀释组 (组Ⅲ, n=6),测定心排血量( CO) ,混合静脉血氧饱和度( SvO2,) 、冠状动脉血流量,计算心肌氧供,氧耗量.于钳扎前、解除钳扎后 20,60 min分别测定血浆中丙二醛 (MDA),SOD活性、磷酸激酶( CPK)及肌酸磷酸激酶同功酶( CK-MB) ,自左心耳剪下标本,测定 HSP 70 mRNA表达率. 结果①缺缺血 20 min 时 3组 MAP、 CI及 SVRI明显减低( P< 0.01) ,但 I组下降幅度明显大于 II,III组.再灌注 60 min时, II组 ,III组 HR明显低于对照值( P< 0.01) ,III组 HR的变化则无统计学意义, I组 MAP,CI的下降幅度明显大 I组和 II组 (P< 0.05).②再灌注 20 min及 60 min时, III组的冠脉血流量明显大于 I组( P< 0.05).③再灌注 20 min和 60 min时, 3组 CPK, CPK-MB均较对照值明显升高( P< 0.05- 0.01) ,组 I的升高幅度明显大于组 II, 组 III.组Ⅰ SOD值在再灌注 20 min, 60 min时逐步降低( P< 0.05),组 II, 组 III SOD值有升高趋势,与对照值比较,无统计学意义.再灌注 60 min时,组Ⅰ MDA值明显高于组Ⅱ,组Ⅲ.④组Ⅰ HSP 70 mRNA表达低于组Ⅱ和组Ⅲ. 结论等容血液稀释可明显增强预适应拮抗心肌缺血再灌注造成的心肌损伤.     

肺表面活性物质稀释剂延迟肺灌洗治疗烟雾吸入性损伤

目的 探讨外源性肺表面活性物质(PS)稀释剂延迟肺灌洗对大鼠严重烟雾吸入伤后内源性PS功能障碍和急性呼吸衰竭的治疗效果.方法 90只Wistar大鼠随机分为5组:Ⅰ组,正常对照(n=14);Ⅱ组,烟雾吸入(n=27);Ⅲ组,烟雾+PS灌洗+机械通气(MV),n=21;Ⅳ组,烟雾+盐水灌洗+MV,n=10;V组,烟雾+MV,n=18.伤后2 h经气管插管注入含PS(100ms/ks)的等渗盐水30 ml/kg或等量盐水行肺灌洗,MV 4 h,观察24 h;检测动脉血气、肺水量、静态肺顺应性(Cst)、支气管肺泡灌洗液(BAIF)蛋白含量、BALF表面张力特性和24 h病死率等.结果 致伤动物伤后立即出现严重缺氧和一氧化碳中毒;Ⅱ组发生急性呼吸衰竭、高通透性肺水肿和PS功能障碍;Ⅲ组Cst和BALF表面张力特性显著改善(P<0.05),但氧合能力、肺水量和BALF蛋白含量无明显好转(P>0.05).Ⅳ、V组疗效不佳.结论 外源性PS稀释剂延迟肺灌洗可一定程度恢复烟雾吸入所致内源性PS功能抑制,改善肺功能,但不能显著减轻高通透性肺水肿和呼吸衰竭,不能降低早期病死率.     

高碳酸血症对急性肺损伤氧自由基生成的影响

目的 观察高碳酸血症对兔急性肺损伤(ALI)模型是否具有保护作用,并观察其对ALI时氧自由基生成的影响,探讨高碳酸血症对ALI可能的作用机制.方法 于中国医科大学药理学实验室将22只新西兰大白兔随机分为对照组(C组,n=6)、非高CO2通气组(N组,n=8)、高CO2(8%CO2)通气组(H组,n=8).将动物气管切开,进行机械通气.N组和H组通过静脉注射油酸(0.1 ml/kg)复制ALI模型.C组给予生理盐水(0.1 ml/kg).监测肺组织呼吸力学指标、血气分析指标的变化.继续机械通气至3 h,将动物处死,取出心肺,检测肺组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,测定肺组织湿质量/干质量比、肺通透指数等指标并观察肺组织病理学改变.结果 H组气道峰压显著低于N组,动态胸肺顺应性显著高于N组,动脉血氧分压H组明显高于N组(P＜0.05).肺组织中MDA含量H组明显低于N组(P＜O.05);SOD活性H组明显高于N组(P＜0.05);肺湿质量/干质量比及肺通透指数H组明显低于N组(P＜0.05).H组病理组织学改变较N组明显减轻.结论 机械通气时吸入8%的CO2所致高碳酸血症对ALI动物模型有一定的保护作用,其机制可能与提高了肺组织中SOD活力,减轻了脂质过氧化有关.     

Aminoterminal procollagen III peptide elevation in alcoholics who are selenium and vitamin E deficient

Serum aminoterminal procollagen III peptide (PIIIP) was measured in 36 alcoholic subjects. There was a significant elevation of PIIIP in subjects with proven liver disease (median 17.5 ng/ml, n = 24) compared to those without liver disease (median 4.7 ng/ml, n = 12). Those subjects with raised serum transaminase values (AST) had elevated PIIIP values (median 13.7 ng/ml, n = 22) compared to those with normal transaminase values (median 3.7 ng/ml, n = 14). In those alcoholic subjects who were deficient in both selenium and vitamin E there was a significant elevation (p less than 0.01) of PIIIP values (median 26.4 ng/ml, n = 7) compared to subjects with normal levels (median 7 ng/ml, n = 11). Subjects deficient in selenium alone had PIIIP values in an intermediate range. Selenium and vitamin E, as important free radical scavengers, may protect the liver in alcoholic subjects from oxidative damage leading to hepatic fibrosis.     

The effects of thromboxane synthase inhibition on reperfusion injury and endothelin-1,2 levels in allograft kidney transplantation in rats

Thromboxane A₂ is a proaggregative vasoconstrictor that is synthesized and released in reperfusion injury. We aimed to investigate the effects of thromboxane synthase inhibitor, UK 38485, on endothelin-1,2 (ET) response of the renal endothelium and lipid peroxidation and protein oxidation in the early period of kidney transplantation. Four groups (n =8) of Sprague-Dawley rats were designed as Group I (sham nephrectomy), Group II (auto-transplantation), Group III (allotransplantation) and Group IV (allotransplantation group in which the allografts were perfused with UK 38485. All subjects underwent right nephrectomy after transplantation. The grafts were flushed with 4 ml of ice-cold Ringer’s lactate and in Group IV 10 μg of UK 38485 was added into the solution for each kidney. In allotransplantation groups, the kidneys were harvested from allogeneic white Wistar albino rats. The kidney grafts were allowed 120 min of reperfusion after 40 min of cold ischemic period. ET-1,2 plasma concentrations in the renal vein blood and diene conjugates (DC), hydroxyalkanals (HAA), hydroxyalkenals (HAE) and malondialdehyde (MDA) levels as the products of lipid peroxidation, protein carbonyls and protein sulfhydryls as the indicators of protein oxidation were analyzed in kidney tissue. Plasma ET-1,2 concentrations increased significantly in Group II and Group III (P<0.01) when compared to Group I but decreased in Group IV in comparison with Group III (P<0.05). DC, HAA, HAE and MDA levels increased in Groups II and III (P<0.001). Significant protein oxidation occurred only in Group III (P<0.01). Perfusion of the allografts with UK 38485 prevented lipid peroxidation and protein oxidation in Group IV. Histopathological changes were mild in the last group. We concluded that, in kidney transplantation, local administration of UK 38485 has cytopreservative effects on the allografts and this effect can be related to ET-1,2 concentrations.     

Antioxidant enzyme activities and malondialdehyde levels related to aging

BACKGROUND: Free oxygen radicals have been proposed as important causative agents of aging. We have evaluated age-related changes in antioxidant enzyme activities and lipid peroxidation. METHODS: We measured erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and plasma malondialdehyde (MDA) levels. One hundred and seventy six healthy subjects were divided into five groups: Group 1 (n = 25; 0.2-1 year-old), Group 2 (n = 28; 2-11 years), Group 3 (n = 23: 12-24 years), Group 4 (n = 40; 25-40 years), Group 5 (n = 60: 41-69 years). RESULTS: SOD activities in Group 5 were significantly lower than in the other groups (P < 0.001). GPx and CAT activities and MDA levels in Group 5 were significantly higher than the other groups (P < 0.001, respectively). CAT activity in Group 4 was significantly higher than group 1 and group 2 (respectively, P < 0.001), and in group 3 was high compared to Group 2 (P < 0.001). There were negative correlations between SOD activities and age (P < 0.001). Conversely, there were positive correlations between CAT, GPx and MDA levels and age (P < 0.001). CAT activities of women in Group 2 were found to be high compared to the men (P < 0.05). MDA levels of women in Group 5 were higher than in the male groups (P < 0.001). CONCLUSIONS: We found age-related differences in erythrocyte antioxidant enzyme activities. Furthermore, peroxidative injury is raised in the aging process.     

大黄对大鼠肠缺血再灌注所致肺损伤的作用

背景:肠道因素尤其是肠缺血再灌注可导致远隔器官损伤是创伤。中药大黄能通过清除氧自由基,促进肠粘膜内杯状细胞增生,抑制肠道内细菌过度繁殖和肠道内毒素吸收及活血化瘀、改善微循环等途径发挥良好的肠黏膜屏障保护作用,进而可能发挥防治肺损伤的作用。目的:观察大黄对肠缺血-再灌注所致肺损伤的防治效应,以及对肿瘤坏死因子和磷脂酶A2的影响。设计:随机对照观察。单位:解放军兰州军区乌鲁木齐总医院急诊科。材料:实验于2003-02/07在解放军第二军医大学完成。选取SD大鼠80只,随机分为肠缺血再灌注组24只,假手术组16只,治疗组24只,生理盐水组16只四组。方法:肠缺血-再灌注组,术前禁食,麻醉,然后经腹正中切口,分离肠系膜上动脉,无创血管夹夹闭之,缝合切口;45min后取出动物夹,恢复血供。治疗组造模同肠缺血再灌注组,恢复血供前30min经胃管灌入精黄片600mg/kg混悬液,。生理盐水组造模同肠缺血再灌注组,于恢复血供前30min经胃管灌入等量的生理盐水。假手术组除不夹闭肠系膜上动脉外,其余手术过程均同肠缺血-再灌注组。以病理学改变及125Ⅰ标记牛血清白蛋白肺摄取指数作为评价肺损伤的指标,分别测定各组动物不同时间肺组织TNF含量及血清、肺及小肠组织PLA2活性。主要观察指标:观察125Ⅰ标记牛血清白蛋白肺摄取指数,血浆、肺组织肿瘤坏死因子含量,血清、肺及小肠组织磷脂酶A2活性。结果:①肺组织病理形态学变化:假手术组未见明显异常;肠缺血再灌注组6h后肺间质出现水肿,并有中性粒细胞浸润,可见肺泡水肿,有少量出血及纤维蛋白渗出。治疗组仅见轻度肺间质水肿及少量中性粒细胞。②肺组织超微病理变化:假手术组未见明显变化。肠缺血再灌注组6h后,可见肺毛细血管内皮细胞肿胀,中性粒细胞向肺间质及肺泡腔渗出。治疗组无上述变化。③肺组织肿瘤坏死因子变化:假手术组和治疗组(再灌注组30min)明显低于肠缺血再灌注组(再灌注30min)(0.235±0.114,1.374±0.550,16.315±4.587,P<0.01)。④125Ⅰ-BSA肺摄取指数:治疗组明显低于肠缺血-再灌注组和生理盐水组(P<0.01),与假手术组差异无显著性(P>0.05)。结论:早期应用大黄有助于防治肠源性肺损伤的发生。进而发挥组织病程向多器官功能不全综合征发展的重要作用,这种作用可能是通过抑制TNF和PLA2等介质的释放实现的。     

左旋精氨酸对兔肺缺血/再灌注损伤时细胞凋亡的影响

目的观察左旋精氨酸对免肺缺血／再灌注损伤中细胞凋亡的影响。方法复制单侧免肺缺血／再灌注损伤模型．随机分为三组：对照组（C组）、缺血／再灌注组（I／R组）和左旋精氨酸组（L—Arg组），每组10只。再灌注180min时取肺组织，观察超氧化物歧化酶（SOD）活性、丙二醛（MDA）浓度、一氧化氮（NO）含量、肺湿干比（W／D）、肺泡损伤数定量评价指标（IQA）及肺组织细胞凋亡指数（At）。结果I／R组与C组比较，SOD活性、NO含量明显降低（P〈0．01），MDA、W／D、IQA、AI明显升高（P〈0．01），L—Arg组与I／R组相比较，SOD活性、NO含量均明显升高（P〈0．01），MDA、W／D、IQA、AI不同程度降低（P〈0．05）。结论左旋精氨酸可通过提高体内NO水平、降低氧自由基水平、减轻脂质过氧化反应，抑制肺组织细胞凋亡，从而减轻肺损伤。     

异丙酚对大鼠肾缺血-再灌注后肺损伤的影响

目的:探讨异丙酚对肾缺血-再灌注后肺损伤是否具有保护作用,以及在不同时间点给予异丙酚,其保护作用是否有差异。方法:Wistar大鼠48只,随机分为假手术对照组(C组)、肾缺血-再灌注组(R组),以及异丙酚用药组[分别在缺血前1h(P1组)、缺血即刻(P2组)、再灌注即刻(P3组)和再灌注后1h(P4组)给予异丙酚],共6组,异丙酚输注速度为20mg/(kg·h),共3h。制作肾缺血-再灌注模型。实验结束即刻取动物血样及肺组织,测定超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量以及肺组织形态学变化。结果:与C组相比,R组红细胞及肺组织的SOD活性明显降低(均P<0.01),血清及肺组织的MDA含量明显升高(均P<0.01),光镜下,R组肺组织结构明显受损;与R组相比,各用药组除P4组外,均有所改善;各用药组间变化也有差异。结论:肾缺血-再灌注会引起肺损伤;异丙酚对肾缺血-再灌注所造成的肺损伤有良好的保护作用;给药时间点不同,对异丙酚的保护作用有影响。     

7-硝基吲唑在烟雾吸入性肺损伤中的作用

目的 探讨神经型一氧化氮合酶（nNOS）抑制剂7-硝基吲唑（7-NI）在烟雾吸入性肺损伤中的作用。方法 40只SD雄性大鼠被随机分为正常对照组（n=8）、烟雾吸入性肺损伤模型组（n=16）和7-NI治疗组（n=16），建立烟雾吸入性肺损伤模型。7-NI治疗组在致伤后立即腹腔注射7-NI 20mg／kg（溶于2ml花生油中）；正常对照组及模型组腹腔注射2ml花生油。分别于伤后2、6、12和24h时间点监测动脉血气分析；并分批处死大鼠，取肺组织测肺含水量，制备肺组织匀浆检测超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、各型一氧化氮合酶（NOS）活性及肿瘤坏死因子-α（TNF—α）和一氧化氮（NO）含量。光镜下观察肺组织病理学变化。结果 与模型组比较，7～NI治疗组各时间点动脉血氧分压均显著升高（P均〈0．05），肺组织含水量显著降低（P〈0．05），肺组织中SOD及CAT活性均明显升高（P均〈0．05），nNOS活性及NO含量均明显降低（P均〈0．05）。治疗组2h和6h肺组织中TNF—α含量均较模型组降低（P均〈0．05）。光镜下7-NI治疗组较模型组损伤程度减轻，炎性细胞浸润减少，肺间质内未见点状出血。结论 7-NI对烟雾吸人性肺损伤有较好的保护作用，可提高动脉血氧分压，减轻肺水肿程度，增加组织抗氧化能力，并减轻组织炎性细胞浸润。     

线粒体ATP敏感钾通道开放剂对大鼠肺缺血-再灌注损伤的保护作用

目的 探讨线粒体ATP敏感钾通道开放剂二氮嗪(DE)对肺缺血-再灌注损伤(I/R)的保护作用.方法 建立大鼠肺I/R模型,随机设立假手术(sham)组、I/R组、DE组、线粒体ATP敏感钾通道阻断剂5-羟基葵酸(5-HD)组,每组10只,观察各组肺组织病理形态学变化,测定肺湿/干质量比,检测肺组织髓过氧化物酶(MPO)活性、丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性.结果 与sham组比较,I/R组肺组织出现明显损伤性病理形态学变化,肺湿/干质量比明显增加(P<0.05),肺组织MPO活性显著增高、MDA含量显著增加和SOD活性显著降低(P<0.05).与I/R组比较,DE组肺组织损伤明显减轻,肺湿/干质量比降低(P<0.05),肺组织MPO活性降低、MDA含量减少、SOD活性增高(P< 0.05).5-HD组各观察指标与I/R组差异无统计学意义(P>0.05).结论 线粒体ATP敏感钾通道开放剂DE可通过抑制中性粒细胞聚集、减少自由基产生、增强抗氧化能力对大鼠肺缺血-再灌注损伤产生明显保护作用,该保护作用可被线粒体ATP敏感钾通道阻断剂5-HD所拮抗.     

Aerosolized beta(2)-adrenergic agonists achieve therapeutic levels in the pulmonary edema fluid of ventilated patients with acute respiratory failure

OBJECTIVE: Experimental studies demonstrate that beta-adrenergic agonists markedly stimulate alveolar fluid clearance if concentrations of 10(-6) M are achieved in alveolar fluid. However, no studies have determined whether aerosolized beta-adrenergic agonists are delivered to the distal air spaces of the lung in therapeutic concentrations in patients with pulmonary edema. DESIGN AND SETTING: This retrospective study measured albuterol levels in the pulmonary edema fluid and plasma from mechanically ventilated patients with pulmonary edema from a hydrostatic mechanism ( n=10) or from acute lung injury ( n=12). MEASUREMENTS AND RESULTS: After a total aerosolized albuterol dose of 4.2+/-3.2 mg in the prior 6 h the median pulmonary edema fluid albuterol level was 1,250 ng/ml (10(-6) M) in patients with hydrostatic pulmonary edema; after 3.5+/-2.6 mg the figure was 1,240 ng/ml (10(-6) M) in patients with pulmonary edema from acute lung injury. Plasma albuterol levels were much lower, with a median of 5.2 ng/ml (0.01 x 10(-6) M) in patients with hydrostatic pulmonary edema and 3.1 ng/ml (0.01 x 10(-6) M) in patients with pulmonary edema from acute lung injury. CONCLUSIONS: These results provide the first evidence that levels of beta-adrenergic agonists that are physiologically efficacious in experimental models can be achieved with conventional delivery systems in ventilated, critically ill patients with acute respiratory failure from pulmonary edema.     

Nifedipine and diltiazem reduce pulmonary edema formation during postischemic reperfusion of the rabbit lung

A protective effect of calcium antagonists in pulmonary preservation for transplantation has been observed recently. This report focuses on the potential use of diltiazem and nifedipine in the early phase of reperfusion after normothermic pulmonary ischemia. Rabbits weighing 4–5 kg were tracheotomized and ventilated with 50% oxygen. In a control group (group I,n=7), the hilus of the right lung was clamped for 210 min without ischemia of the left lung. Lung ischemia was created in a second group (n=7) by clamping the left hilum for 2 h. Subsequently, reperfusion of the left lung was maintained for 210 min, while the right hilus was kept occluded. In group III (n=6) and group IV (n=8) the conditions were the same as in group II, but either diltiazem (62.5 μg/kg i.v., group III) or nifedipine (3 μg/kg i.v., group IV) was administered during the first 20 min of reperfusion. After 210 min of reperfusion, the pulmunary vascular resistance was elevated in group II (×: 5120 dyn·sec·cm⁻⁵), group III (5518 dyn·sec·cm⁻⁵), and group IV (4324 dyn·sec·cm⁻⁵), compared with group I (3390; n.s.). Arterial oxygenation showed no significant differences among group I (×: 257 mmHg), group II (261 mmHg), group III (208 mmHg), and group IV (247 mmHg). Pulmonary ischemia resulted in an increased extravascular lung water content in group II as compared to group I (73 and 64 g/g wet weight;P<0.0125 vs group I). No such increase was seen in groups III and IV (53 and 54 g/g wet weight respectively;P<0.001 vs group II). In this model of normothermic left lung ischemia, the application of diltiazem or nifedipine during the early phase of reperfusion limits formation of pulmonary edema. In constrast to previous findings using verapamil, both substances do not show significant influence on pulmonary vascular resistance. They may be of use in clinical lung transplantation by reducing fluid accumulation in the lung parenchyma.     

The changes of superoxide dismutase, catalase and glutathione peroxidase activities in erythrocytes of active and passive smokers.

Cigarette smoking has been implicated in the pathogenesis of ischemic heart disease, emphysema, obstructive lung disease and neoplastic disorders. More than 1000 constituents of smoke, including many oxidants, pro-oxidants, free radicals and reducing agents, have been identified. The activities of erythrocyte superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), which are the important components of antioxidant defense system, were measured in 100 healthy volunteers. This study included heavy smokers (consuming cigarettes > or = 20 per day; n=30, group I), light smokers (consuming cigarettes<20 per day; n=30, group II), passive smokers (exposed to cigarette smoke in the indoor environment; n=20, group III), and non-smokers (n=20, the control group). While activities of SOD and CAT in erythro cytes were significantly lower in groups I, II and III than in the control group (p<0.01 for all), mean erythrocyte GSH-Px activity in group III was higher than that in groups l, II and in controls. These results suggest that the increased oxidative stress occurs in smokers, owing to the free radicals present in smoke. It might cause a decrease in antioxidant enzyme activities and oxidant/antioxidant imbalance. We also observed that passive smokers were affected by the environmental smoke to the same extent as active smokers.     

External113Inm and99Tcm radiation detection of lung edema induced by oleic acid in the guinea pig

The establishment of a small animal model for studies of lung injury is in great demand. Therefore, a double radioisotope labeling method was applied to study the dynamics of lung injury with protein-rich edema in the anesthetized guinea pig. One external scintillation detector was placed over the lung and another over the heart, where they continuously sampled the energy spectrum of 113Inm labeled transferrin, a macromolecular marker, and 99Tcm labeled red blood cells (RBC), a blood pool marker. Lung injury was induced by i.v. oleic acid in doses of 0.03 and 0.06 ml/kg b.wt. infused for 10 min. We calculated the rate of increase of accumulated 113Inm-transferrin in the lung corrected for blood pool changes. Macromolecular leakage showed a graded response in regression line-slope (RLS) to oleic acid. Both oleic acid groups showed significantly different RLSs as compared to the saline control (mean +/- SD x 10(-3) min-1; 0.03 ml: 3.86 +/- 1.01 (n = 7); 0.06 ml: 10.75 +/- 4.06 (n = 6), and control 1.12 +/- 1.19 (n = 6]. Assays of changes of acid-base balance, cell dynamics, and lung wet-dry weight were in accordance with the occurrence of lung edema. The RLS was well correlated with the lung wet-dry weight (r = 0.98). We conclude that measurements of pulmonary edema in guinea pigs can be performed quantitatively with the aid of external detection of radiolabeled transferrin and RBC:s. Thus, the method could be useful in further studies on mechanisms and/or treatment of protein-rich lung edema.     

Clusterin protects the lung from leukocyte-induced injury

Clusterin (CLU) is a multifunctional 75- to 80-kDa glycoprotein that is upregulated during cellular stress and might represent a defense mechanism during local cellular damage. Mechanisms discussed are antiapoptotic, antioxidative, and anticomplement properties as well as chaperone-like features protecting stressed proteins. The aim of this study was to investigate potential protective effects of CLU on pulmonary vasculature after in situ PMN activation in isolated rabbit lungs. The experiments were performed on 24 isolated and ventilated rabbit lungs that were perfused with 200 mL of Krebs-Henseleit-10% blood buffer with a constant flow of 150 mL/min in a recirculating system. It was tested whether pretreatment with CLU (2.5 microg/ml; n = 8) or catalase (CAT, 5000 U/ml; n = 8) before N-formyl-Met-Leu-Phe (fMLP; 10(-8) M) injection influenced pulmonary artery pressure (PAP) peak airway pressures (PAW) and edema formation as compared with controls (n = 8). Baseline values of PAP were 9-11 mmHg and PAW 11-13 cm H2O. Application of fMLP resulted in an acute significant (P < 0.01) increase of PAP (48 +/- 29 mmHg) within 2 min in the control group and PAW increased to 35 +/- 7 cm H2O within 30 min. Pretreatment with CLU completely suppressed the PAP and PAW response as a result of the fMLP challenge (P < 0.001), whereas a transient PAW increase up to 27 +/- 15 mmHg was observed after CAT. Complement factor C3a release was suppressed by CAT, whereas CLU blocked the complement cascade at the level of C5b-9 formation. Moreover, generation of thromboxane A(2) was reduced after CLU and CAT. Lung edema occurred in the fMLP group but was absent (P < 0.001) after CLU and CAT treatment. Both CLU and CAT prevented fMLP-induced lung injury. Stabilizing effects of CLU, point towards complement regulating features at the level of the terminal complement sequence. Elevated levels of CLU during inflammation could reflect a compensatory organ protective mechanism. Further studies are required to elucidate the clinical impact of the observed organ-protective properties of CLU.     

The development of acute respiratory distress syndrome after gut ischemia/reperfusion injury followed by fecal peritonitis in pigs: a clinically relevant model

Numerous clinical trials using anti-inflammatory agents for patients with acute respiratory distress syndrome (ARDS) have failed despite efficacy in acute animal models. This underscores the necessity of developing a clinically relevant model of ARDS. Initially, we attempted to induce lung injury in pigs by fecal peritonitis only. When this was unsuccessful, we designed a two-hit model of ischemia/reperfusion (I/R) injury followed by fecal peritonitis to create a clinically applicable model of ARDS. The initial study consisted of Yorkshire swine [group 1, fecal clot (FC), n = 4] that were followed clinically after intraperitoneal placement of a fecal (0.5 mL/kg) blood (2 mL/kg) clot. Blood was sampled daily for cultures, a complete blood count, a lactate level, and various cytokine expression determined by enzyme-linked immunosorbent assay (ELISA). Pigs were treated with antibiotics and fluids, placed on a ventilator before sacrifice to obtain hemodynamic and pulmonary parameters, and underwent histologic lung assessment. Additionally, bronchoalveolar lavage fluid was obtained for protein concentration and cytokine levels. Once it was evident that no lung injury had occurred, we designed a more severe model. A second group of Yorkshire swine [group 2, superior mesenteric artery (SMA) + FC, n = 4] underwent SMA occlusion for 30 min (I/R) followed by intraperitoneal placement of a FC as in the initial group. These pigs were monitored more invasively and continuously in an intensive care setting for 48 h and followed, treated, and assessed in a similar fashion to group 1. Group 1 (FC) pigs survived 9 days and showed signs of sepsis (bacteremia with polymicrobial organisms), an inflammatory response in the form of elevated cytokines, yet no physiologic or histologic evidence of lung injury. Group 2 (SMA + FC) pigs demonstrated more severe sepsis, a significantly increased cytokine response compared with animals in the FC group, and physiologic signs of progressive pulmonary injury. Pigs in the SMA + FC group were sacrificed at 48 h after clinical deterioration (significant decline in oxygenation) and demonstrated pathologic evidence of lung injury indicated by increased bronchoalveolar lavage fluid protein, diffuse and thickened alveolar septae, hyaline membrane formation, and pulmonary edema. The addition of a second "hit" (SMA occlusion, I/R) to a FC sepsis model resulted in severe lung injury that developed within a 3-day period. To our knowledge, this is the first large animal experiment that definitively and consistently causes insidious onset ARDS in pigs. By closely paralleling the clinical development of pulmonary injury, this model should prove invaluable in the study of human ARDS.     

Effects of polyethylene glycol-linked superoxide dismutase and catalase during in vivo lung ischemia and reperfusion

We have previously demonstrated that reperfusion of a rabbit lung following 24 hours of in vivo pulmonary artery occlusion results in bilateral lung edema and lung inflammation and in systemic leukopenia. We tested whether this in vivo ischemia/reperfusion lung injury in the rabbit could be prevented by the administration of superoxide dismutase (SOD) and catalase (CAT). Polyethylene glycol-linked SOD (PEG-SOD) and CAT (PEG-CAT) were administered to five rabbits, PEG-SOD alone to four rabbits, and neither to nine untreated control rabbits, and the left pulmonary artery was then occluded with a microvascular clamp. Enzyme activity measured at the time of reperfusion 24 hours later demonstrated plasma CAT activity of 1,127 ± 601 U/mL for SOD/CAT-treated rabbits versus 193 ± 25 U / mL for untreated rabbits (P < .05) and SOD activity of 97 ± 25 U/mLfor SOD-treated rabbits versus no measurable activity in untreated rabbits. Following 4 hours of reperfusion, wet to dry ratios were 6.15 ± 0.27 for the reperfused left lungs and 5.55 ± 0.20 for the right lungs. Analysis of variance demonstrated a significant effect of reperfusion on left versus right wet to dry ratios (P < .05) but no effect of enzyme treatment. Lung sections scored by a blinded observer for histologic evidence of lung injury similarly showed a left-to-right difference but no difference between treated and untreated animals in degree of injury to the reperfused left lung. However, the contralateral lung was relatively less injured in treated rabbits. The two groups also differed in that an immediate leukopenia developed following reperfusion in the untreated and PEG-SOD-treated rabbits but not in the rabbits treated with both PEG-SOD and PEG-CAT. We conclude that SOD and CAT prevent the systemic leukopenia that accompanies pulmonary artery reperfusion, but do not prevent the injury to the reperfused lung. The sparing effect on the contralateral lung suggests that the mechanism of injury for that lung differs from the mechanism of injury to the occluded lung.