Inducible nitric oxide synthase gene knockout mice have increased resistance to gut injury and bacterial translocation after an intestinal ischemia-reperfusion injury

OBJECTIVE: Intestinal ischemia-reperfusion after severe shock states is often associated with bacterial translocation and intestinal barrier dysfunction. Our previous studies showed that inducible nitric oxide synthase (iNOS) gene knockout mice were resistant to endotoxin-induced bacterial translocation and ileal mucosal damage. The goal of this study was to test whether iNOS mediates bacterial translocation after intestinal ischemia-reperfusion, using iNOS knockout mice (iNOS-/-) and their wild-type littermates (iNOS+/+). DESIGN: Prospective animal study with concurrent controls. SETTING: Small animal laboratory. SUBJECTS: Thirty-eight iNOS knockout mice and 51 wild-type littermates. INTERVENTIONS: iNOS+/+ mice or iNOS-/- mice were subjected to a sham operation or 30 mins of superior mesenteric artery occlusion followed by reperfusion. Twenty-four hours after reperfusion, bacterial translocation to mesenteric lymph nodes, ileal villous damage, and cecal bacterial population were evaluated. MEASUREMENTS AND MAIN RESULTS: Sham operation did not induce bacterial translocation, change cecal bacterial population levels, or cause ileal villous damage. Intestinal ischemia-reperfusion caused bacterial translocation in 72% of the iNOS+/+ mice but only 28% of the iNOS-/- mice. Both iNOS+/+ and iNOS-/- mice subjected to superior mesenteric artery occlusion (SMAO) in which bacterial translocation occurred had cecal bacterial population levels that were three logs higher than mice subjected to sham SMAO or mice subjected to SMAO in which bacterial translocation did not occur. The magnitude of villous injury was less in the iNOS-/- mice than the iNOS+/+ mice after SMAO, although the incidence of ileal villous damage was significantly higher in both the iNOS+/+ and iNOS-/- mice in which bacterial translocation occurred after SMAO than in the mice in which bacterial translocation did not occur after SMAO. iNOS+/+ mice subjected to SMAO had increased plasma concentrations of nitrite (NO2-) and nitrate (NO3-), and the plasma concentrations of NO2- and NO3- were highest in the mice in which bacterial translocation had occurred. CONCLUSION: iNOS knockout mice were more resistant to intestinal ischemia-reperfusion-induced bacterial translocation and mucosal injury than wild-type mice, suggesting that iNOS might play a role in intestinal ischemia-reperfusion-induced loss of gut barrier function.     

Gut luminal microdialysis of glycerol as a marker of intestinal ischemic injury and recovery

OBJECTIVE: To evaluate microdialysis as a method to assess different degrees of intestinal damage and recovery during ischemia and reperfusion; to evaluate information obtained from microdialysis catheters in the peritoneum, the gut wall, and the gut lumen. DESIGN: Randomized, controlled animal experiment. SETTING: University laboratory animal center. SUBJECTS: Twenty-seven domestic pigs. INTERVENTIONS: The superior mesenteric artery was cross-clamped for 60 mins (n = 14) or 120 mins (n = 10) followed by 2 or 4 hrs of reperfusion. Three pigs served as controls. MEASUREMENTS AND MAIN RESULTS: Intestinal mucosal integrity was assessed by morphometry, adenosine triphosphate in the gut wall, and permeability of C-polyethylene glycol. Lactate, glycerol, pyruvate, and glucose were measured by microdialysis. Changes in adenosine triphosphate, permeability, or lactate did not correlate to different extents of intestinal damage caused by 60 or 120 mins of ischemia. During the reperfusion period, pigs with 60 mins of intestinal ischemia showed a faster recovery of these variables than pigs with 120 mins of intestinal ischemia. Glycerol increased with increasing duration of the ischemic insult. After 60 mins of intestinal ischemia, glycerol in the gut lumen decreased toward baseline but remained high after 120 mins of intestinal ischemia. There was a good correlation between gut luminal glycerol and recovery of mucosal damage throughout the reperfusion period. In the peritoneal cavity, both glycerol and lactate decreased to baseline relatively shortly after onset of reperfusion independent of the duration of intestinal ischemia. CONCLUSIONS: Microdialysis of glycerol provides information about the extent and severity of intestinal damage after ischemia and about the ensuing recovery. The gut lumen is to be preferred as a site for placement of microdialysis catheters.     

酸性成纤维细胞生长因子促进大鼠肠缺血-再灌注损伤的修复

背景：细胞外调节蛋白激酶和酸性成纤维细胞生长因子受体2在肠缺血-再灌注损伤修复中的作用尚无研究报道。目的：观察大鼠肠缺血-再灌注损伤后外源性酸性成纤维细胞生长因子对细胞外调节蛋白激酶和酸性成纤维细胞生长因子受体2表达的影响,探讨细胞外调节蛋白激酶和酸性成纤维细胞生长因子受体2与酸性成纤维细胞生长因子促进创伤修复的关系。方法：以大鼠肠系膜上动脉夹闭45min造成肠缺血-再灌注损伤模型,于再灌注即刻应用酸性成纤维细胞生长因子行干预。分别于再灌注2,6,12,24h取大鼠小肠组织标本,利用免疫组化和RT-PCR检测酸性成纤维细胞生长因子受体的表达及免疫组化检测细胞外调节蛋白激酶表达的规律。结果与结论：在正常大鼠,酸性成纤维细胞生长因子受体2主要分布在小肠绒毛上皮细胞的肠腔侧、侧壁和小肠隐窝朝向隐窝腔的一侧细胞膜上。缺血-再灌注初期,酸性成纤维细胞生长因子受体2及细胞外调节蛋白激酶的表达未发生明显变化,但随着再灌注时间的延长表达水平逐渐提高,并于再灌注后6-12h达高峰。经酸性成纤维细胞生长因子治疗后,大鼠小肠组织小肠黏膜损伤程度减轻,酸性成纤维细胞生长因子受体2及细胞外调节蛋白激酶的表达量高于未治疗大鼠。结果表明缺血-再灌注损伤后,酸性成纤维细胞生长因子干预可上调酸性成纤维细胞生长因子受体2及细胞外调节蛋白激酶的表达,提示外源性酸性成纤维细胞生长因子通过促进内源性酸性成纤维细胞生长因子受体2和细胞外调节蛋白激酶的生成可能是其参与内脏损伤修复的机制之一。     

大黄对大鼠肠缺血再灌注所致肺损伤过程中内源性NO的影响

目的　在大鼠小肠缺血再灌注（ＩＩＲ） 模型上,研究内源性一氧化氮（ＮＯ）在ＩＩＲ所致肺损伤发病过程中的作用;观察大黄对ＮＯ的影响,探讨大黄防治肠源性肺损伤的机理。方法　ＳＤ大鼠随机分为肠缺血再灌注组、假手术组、大黄治疗组和安慰剂组监测平均动脉压（ＭＡＰ）。以１２５Ｉ标记小牛血清白蛋白（ＢＳＡ） 肺摄取指数作为评价肺毛细血管通透性的指标;采用镉还原柱层析和比色法分别测定各组动物不同时间血浆、肺及小肠组织内源性ＮＯ的含量。结果　大黄可明显改善ＩＩＲ导致的低血压状态;抑制血浆、肺及小肠组织内源性ＮＯ的释放（ Ｐ＜ ０－０５ 或Ｐ＜０－０１）;降低肺毛细血管通透性（ Ｐ＜ ０－０１） 。结论　早期应用大黄有助于防止大鼠肠源性肺损伤的发生,这种作用部分是通过抑制内源性ＮＯ大量释放实现的。     

Myocardial ischemia in intestinal postischemic shock: the effect of hypoxemic reperfusion

OBJECTIVE: The circulatory shock following intestinal ischemia-reperfusion injury has been attributed to hypovolemia. The purpose of the current study is to clarify the pathophysiology of this type of shock and to test the hypothesis that hypoxemic compared with normoxemic reperfusion improves hemodynamics. DESIGN: Randomized animal study. SETTING: Medical school laboratory. SUBJECTS: Twenty-one pigs. INTERVENTIONS: Pigs were subjected to 120 mins of intestinal ischemia by clamping the superior mesenteric artery. Upon declamping, the animals were randomized into two groups: a group that received hypoxemic reperfusion (HR group, n = 8) with a PaO2 = 30-35 and a control group reperfused with PaO2 = 100 mm Hg (control group, n = 13). MEASUREMENTS AND MAIN RESULTS: Measurements included mean arterial pressure, cardiac index, pulmonary artery occlusion pressure, and requirements for fluids and epinephrine. Biopsies from the terminal ileal mucosa were taken for malondialdehyde measurements at baseline, at 120 mins of ischemia, and at 30 and 60 mins of reperfusion. A piece of left ventricle was obtained after 120 mins of reperfusion for histologic studies. Five of 13 animals of the control group died in intractable shock; no animal of the HR group died (p =.11). The decrease in the mean arterial pressure during reperfusion was more pronounced in the control group (p <.008) despite the larger doses of epinephrine administered, compared with the HR group (p <.02). During reperfusion, both groups exhibited a decrease in cardiac index; this was more pronounced in the control group (p =.0007). Pulmonary artery occlusion pressure increased during reperfusion in both groups and was more pronounced in the control group (p =.04 at 60 mins). Although mixed venous blood oxygen saturation of the control animals was higher at 30 mins of reperfusion (p =.005), it declined after 60 mins and became lower than that of HR animals at the end of reperfusion (p <.02). The myocardial histopathologic injury score was higher in the control group (2.0 +/- 0.69 and 3.4 +/- 0.89 for the HR and control groups, respectively; p <.03). The concentrations of intestinal mucosa malondialdehyde were significantly higher in the control group at 60 mins of reperfusion (p <.03). CONCLUSIONS: Acute myocardial ischemia and left heart failure significantly contribute to the circulatory shock that follows intestinal ischemia/reperfusion injury and are attenuated by hypoxemic reperfusion.     

Regeneration of small bowel mucosa after intestinal ischemia.

BACKGROUND AND METHODS: The objective of this study was to evaluate the histologic reconstitution of the small intestinal mucosa after a standardized ischemic injury and to determine if the early repair process takes place by cell renewal or migration of existing mucosal cells. Therefore, male Wistar rats, weighing 190 to 320 g, were subjected to total warm intestinal ischemia by means of a hydrostatic pressure clamp for 45 or 90 mins. These rats were compared to sham-operated controls. Intestinal biopsies were obtained just before reperfusion and at various times up to 48 hrs thereafter. Mucosal injury was evaluated microscopically by a blinded examiner. RESULTS: Variable mucosal reconstitution occurred within 3 hrs, after 45 mins of ischemia, whereas mucosal repair required up to 18 hrs after 90 mins of ischemia. In a second series of experiments, 45 or 90 mins of ischemia and 5 hrs of reperfusion were followed by the iv administration of radioactively labeled thymidine. Intestinal biopsies were taken 1 hr later and prepared for autoradiography. No increase in mucosal mitoses was observed. CONCLUSIONS: The mucosal reconstitution occurred rapidly after 45 mins and 90 mins of total warm intestinal ischemia and primarily through mucosal cell migration.     

Nitric oxide mediates lung vascular permeability and lymph-borne IL-6 after an intestinal ischemic insult

Acute lung injury following intestinal I/R depends on neutrophil-endothelial cell interactions and on cytokines drained from the gut through the lymph. Among the mediators generated during I/R, increased serum levels of IL-6 and NO are also found and might be involved in acute lung injury. Once intestinal ischemia itself may be a factor of tissue injury, in this study, we investigated the presence of IL-6 in lymph after intestinal ischemia and its effects on human umbilical vein endothelial cells (HUVECs) detachment. The involvement of NO on the increase of lung and intestinal microvascular permeability and the lymph effects on HUVEC detachment were also studied. Upon anesthesia, male Wistar rats were subjected to occlusion of the superior mesenteric artery during 45 min, followed by 2-h intestinal reperfusion. Rats were treated with the nonselective NO synthase (NOS) inhibitor L-NAME (N(omega)-nitro-L-arginine methyl ester) or with the selective inhibitor of iNOS aminoguanidine 1 h before superior mesenteric artery occlusion. Whereas treatment with L-NAME during ischemia increased both IL-6 levels in lymph and lung microvascular permeability, aminoguanidine restored the augmented intestinal plasma extravasation due to ischemia and did not induce IL-6 in lymph. On the other hand, IL-6 and lymph of intestinal I/R detached the HUVECs, whereas lymph of ischemic rats upon L-NAME treatment when incubated with anti-IL-6 prevented HUVEC detachment. It is shown that the intestinal ischemia itself is sufficient to increase intestinal microvascular permeability with involvement of iNOS activation. Intestinal ischemia and absence of constitutive NOS activity leading to additional intestinal stress both cause release of IL-6 and increase of lung microvascular permeability. Because anti-IL-6 prevented the endothelial cell injury caused by lymph at the ischemia period, the lymph-borne IL-6 might be involved with endothelial cell activation. At the reperfusion period, this cytokine does not seem to be modulated by NO.     

Inhibition of coagulation and inflammation by activated protein C or antithrombin reduces intestinal ischemia/reperfusion injury in rats

OBJECTIVE: To examine whether administration of activated protein C or antithrombin reduces local splanchnic derangement of coagulation and inflammation and attenuates intestinal dysfunction and injury following intestinal ischemia/reperfusion. DESIGN: Randomized prospective animal study. SETTING: University research institute. SUBJECTS: Adult male Wistar rats, weighing 300-325 g (n = 72). INTERVENTIONS: Rats were subjected to superior mesenteric artery occlusion consisting of 20 or 40 mins of ischemia and 3 hrs of reperfusion. A randomized intravenous administration of vehicle (0.9% NaCl), heparin, antithrombin, or activated protein C was performed during ischemia, 15 mins before reperfusion. Coagulation and fibrinolysis variables obtained from portal blood were correlated with mucosal fibrin deposition (determined by anti-rat fibrin antibody staining), intestinal function (glucose/water clearance), and intestinal injury (histologic evaluation by Park/Chiu score). MEASUREMENTS AND MAIN RESULTS: Activated protein C- or antithrombin-treated animals demonstrated less ischemia/reperfusion-induced intestinal dysfunction and histologic changes compared with control animals, whereas intravenous administration of heparin only showed less histologic derangement. Activated protein C- or antithrombin-treated animals showed less thrombin generation, fibrin degradation products, and fibrin deposition compared with control animals, as confirmed by histologic examination, whereas heparin administration showed only a limited reduction of portal fibrin degradation product concentrations. Furthermore, activated protein C or antithrombin administration markedly inhibited the inflammatory response, as reflected by reduced interleukin-6 plasma concentrations to baseline values, whereas heparin had no effect. CONCLUSIONS: Administration of activated protein C or antithrombin inhibited local and systemic derangement of coagulation and inflammation following intestinal ischemia/reperfusion, diminished mucosal fibrin deposition, and attenuated ischemia/reperfusion-induced intestinal injury. These observations suggest that activated protein C or antithrombin reduces ischemia/reperfusion-induced intestinal injury, both through their anticoagulant and anti-inflammatory effects.     

外源性酸性成纤维细胞生长因子干预肠缺血-再灌注损伤中p38MAPK和成纤维细胞生长因子受体2的表达

背景:酸性成纤维细胞生长因子可以促进多种创面愈合,在内脏损伤修复中起重要促进作用。目的:观察外源性酸性成纤维细胞生长因子干预肠缺血-再灌注损伤大鼠后p38MAPK和成纤维细胞生长因子受体2的表达。方法:以大鼠肠系膜上动脉夹闭45min造成肠缺血-再灌注损伤模型,于再灌注即刻应用改构体酸性成纤维细胞生长因子进行干预。分别于再灌注2,6,12,24h取大鼠小肠组织标本,用于实验。结果与结论:在正常大鼠,成纤维细胞生长因子受体2主要分布在小肠绒毛上皮细胞的肠腔侧、侧壁和小肠隐窝朝向隐窝腔的一侧细胞膜上。缺血-再灌注初期,p38MAPK蛋白及成纤维细胞生长因子受体2蛋白和mRNA的表达未发生明显变化,随着再灌注时间的延长其逐渐增强,并于再灌注后6~12h达高峰。经酸性成纤维细胞生长因子治疗后,大鼠小肠组织p38MAPK蛋白及成纤维细胞生长因子受体2蛋白和mRNA的表达进一步增强,小肠黏膜损伤程度减轻。说明酸性成纤维细胞生长因子可通过上调成纤维细胞生长因子受体2和p38MAPK的表达促进肠缺血-再灌注损伤的修复。     

褪黑素对大鼠肠缺血/再灌注损伤保护作用的实验研究

目的　观察褪黑素对大鼠肠缺血 /再灌注损伤的保护作用。方法　成年雄性SD大鼠 6 0只分为假手术组 (10只 )、缺血 /再灌注组 (10只 )、缺血 /再灌注 溶媒组 (10只 )、缺血 /再灌注 褪黑素 10mg/kg组 (15只 )、缺血 /再灌注 褪黑素2 0mg/kg组 (15只 )。观察肠缺血 30min再灌注 6 0min后肠黏膜损伤程度 ,测定血中D -乳酸和内毒素水平 ,并测定小肠组织中丙二醛 (MDA)、一氧化氮 (NO)水平和诱生型一氧化氮合酶 (iNOS)活力。结果　运用褪黑素组肠黏膜损伤程度轻 ,MDA、NO、iNOS和D -乳酸、内毒素均低于缺血 /再灌注组和溶媒组 ,并呈剂量依赖效应。肠黏膜损伤程度与MDA、NO及D -乳酸呈正相关。结论　运用褪黑素对大鼠肠缺血 /再灌注损伤有保护作用 ,效应呈剂量依赖性。这种作用的部分原因可能是褪黑素抑制了NO的过度生成。     

Evaluation of intestinal preconditioning in a porcine model using classic ischemic preconditioning or lung recruitment maneuvers

To test the hypotheses that repeated brief intestinal ischemic insults would elicit an intestinal preconditioning response to a subsequent intestinal I/R injury and that a similar response would be elicited by repeated lung recruitment maneuvers (RMs). Randomized experimental controlled animal study. University hospital animal laboratory. Eighteen anesthetized pigs. Animals were randomized to one of three groups, with six animals in each group. Control group 75-min superior mesenteric artery (SMA) occlusion followed by 60-min reperfusion. Ischemic preconditioning group, three 5-min-long SMA occlusions preceding 75-min SMA occlusion and 60-min reperfusion. Recruitment maneuver (RM) group, three 2-min-long RMs preceding 75-min SMA occlusion and 60-min reperfusion. We measured systemic and mesenteric hemodynamic parameters, jejunal mucosal perfusion, net mesenteric lactate flux, jejunal tissue oxygen tension, and mesenteric oxygenation. Every 15 min, jejunal microdialysate samples were collected and analyzed for glucose, lactate, and glycerol. Jejunal tissue samples were collected postmortem. After occlusion of SMA, regional parameters in all groups indicated abolished perfusion and gradually increasing intraluminal microdialysate lactate and glycerol levels. At reperfusion, regional parameters indicated mesenteric hyperperfusion, whereas microdialysis markers of mucosal anaerobic metabolism and cell injury decreased, although not reaching baseline. Histological examination revealed severe mucosal injury in all groups. There were no significant differences between groups in the observed parameters. No protective preconditioning response could be observed when performing repeated brief intestinal ischemic insults or repeated lung RMs before an intestinal I/R injury.     

高渗盐水复苏缺血小肠对小肠免疫屏障和系统炎性反应综合征的影响

目的 本研究拟证实利用高渗盐水进行液体复苏可保护缺血-再灌注过程中的肠道黏膜屏障功能,并减轻该过程中机体系统性炎症反应综合征（SIRS）,从而为临床大出血、严重感染、大面积烧伤后肠功能障碍患者液体复苏方案的选择提供新的策略方法和理论依据.方法 ①选用清洁级雄性Sprague-Dawley（SD）大鼠,体重250 g-300 g,通过肠系膜上动脉夹闭法建立大鼠小肠缺血-再灌注损伤模型.②选用清洁级雄性Sprague-Dawley（SD）大鼠,随机分为假手术组（Sham组）,缺血-再灌注损伤组（IR组）和高渗盐水复苏组（HS组）.IR组夹闭肠系膜上动脉1h后开放并经尾静脉输入0.9％氯化钠溶液;HS组夹闭肠系膜上动脉1h后开放并经尾静脉输入7.5％氯化钠溶液;Sham组操作方法同IR组,但不进行肠系膜上动脉夹闭.再灌注6h后取标本.③免疫组化检测小肠粘膜内淋巴细胞（intra-epithelial lymphocyte,IEL）和固有层淋巴细胞（lamina propria lymphocytes,LPL）中T细胞亚群改变;流式细胞术检测大鼠外周血T细胞亚群及NK细胞.结果 ①肠黏膜上皮细胞层中的上皮内淋巴细胞（IEL）和位于疏松结缔组织中的固有层淋巴细胞（LPL）中CD4＋T细胞数量和CD8＋细胞数量,IR组和HS组显著高于Sham组,HS组显著高于IR组.②外周血T细胞亚群及NK分析：HS组CD3＋ CD8＋T细胞显著低于IR组和Sham组（P＜0.05）,HS组NK细胞比例显著低于IR组和NS组（P＜0.05）,余未见显著性差异.结论 利用高渗盐水复苏缺血小肠,可有效保护小肠免疫屏障,抑制全身炎性反应综合征.     

N-乙酰-L-半胱氨酸对肠道缺血-再灌注损伤及远处器官的保护作用

目的：观察补充Ｎ 乙酰 Ｌ 半胱氨酸（ＮＡＣ）在大鼠肠系膜上动脉夹闭致缺血 再灌注损伤时对肠、心和肺的保护作用。方法：大鼠肠系膜上动脉夹闭４５ 分钟后松夹,于松夹前或松夹后５ 分钟给予ＮＡＣ（５０ ｍ ｇ／ｋｇ）,测定松夹后２、４ 和６ 小时肠、心和肺组织总巯基（ＴＳＨ）、非蛋白巯基（ＮＰＳＨ）、丙二醛（ＭＤＡ）和髓过氧化物酶（ＭＰＯ）的改变。结果：给予ＮＡＣ可明显增加组织ＮＰＳＨ水平,降低ＭＤＡ 和ＭＰＯ含量;但松夹后给予ＮＡＣ者效果要优于松夹前给予者。结论：ＮＡＣ通过清除自由基对缺血 再灌注引起的肠和远处器官起到保护作用     

大黄对大鼠肠缺血再灌注致肺损伤中磷脂酶A2的影响

目的 在大鼠小肠缺血再灌注（ＩＩＲ）模型上,研究磷脂酶Ａ２（ＰＬＡ２）在ＩＩＲ所致肺损伤发病过程中的作用,观察大黄对ＰＬＡ２影响,探讨大黄防治肠源性肺损伤的机理。方法 ＳＤ大鼠随机分为肠缺血再灌注组、假手术组、大黄治疗组和安慰剂组。以＾１２５Ｉ标记小牛血清白蛋白（ＢＳＡ）肺摄取指数作为评价肺损伤的指标,以过氧化物酶（ＭＰＯ）作为评价多聚核白细胞（ＰＭＮ）在组织中聚集的指标,分别测定各组动物不同时间     

Pharmacological preconditioning protects lung injury induced by intestinal ischemia/reperfusion in rat

Intestinal ischemia/reperfusion (IIR) is a critical and triggering event in the development of distal organ dysfunction, frequently involving the lungs. Respiratory failure is a common cause of death and complications after intestinal I/R. Stress protein heme oxygenase-1 (HO-1) confers the protection against a variety of oxidant-induced cell and tissue injuries. The aim of this study was to investigate the hypothesis that the induced HO-1 expression by pharmacological preconditioning with anticancer drug doxorubicin (Dox) could protect the lung injury induced by intestinal I/R. Intravenous administration of Dox induced HO-1 expression in the lungs and high levels of the expression were sustained at least to 48 h after the injection. Therefore, as pharmacological preconditioning, a low dose of Dox was injected intravenously into rats at 48 h before the start of intestinal ischemia. Rats underwent intestinal I/R by superior mesenteric artery occlusion for 120 min followed by 120 min of reperfusion. Preconditioning with Dox significantly ameliorated the lung injury induced by the intestinal I/R. Administration of a specific inhibitor of HO activity reduced the efficacy of the preconditioning. Our results suggest that this improvement may be mediated at least in part by the HO-1 induction. These findings may offer interesting perspectives for patient management In Intestinal surgical operation and intestine transplantation.     

Pretreatment with bone morphogenetic protein-7 (BMP-7) mimics ischemia preconditioning following intestinal ischemia/reperfusion injury in the intestine and liver

Intestinal ischemia/reperfusion (I/R) injury has been shown to cause intestinal mucosal injury and adversely affect function. Ischemic preconditioning (IPC) has been shown to protect against intestinal I/R injury by reducing polymorphonuclear leukocyte infiltration, intestinal mucosal injury, and liver injury, and preserve intestinal transit. Bone morphogenetic protein 7 (BMP-7) has been shown to protect against I/R injury in the kidney and brain. Recently, microarray analysis has been used to examine the possible IPC candidate pathways. This work revealed that IPC may work through upregulation of BMP-7. The purpose of this study was to examine if pretreatment with BMP-7 would replicate the effects seen with IPC in the intestine and liver after intestinal I/R. Rats were randomized to six groups: sham, I/R (30 min of superior mesenteric artery occlusion and 6 h of R), IPC+R (three cycles of superior mesenteric artery occlusion for 4 min and R for 10 min), IPC+I/R, BMP-7+R (100 microm/kg recombinant human BMP-7), or BMP-7+I/R. A duodenal catheter was placed, and 30 min before sacrifice, fluorescein isothiocyanate-Dextran was injected. At sacrifice, dye concentrations were measured to determine intestinal transit. Ileal mucosal injury was determined by histology and myeloperoxidase activity was used as a marker of polymorphonuclear leukocyte infiltration. Serum levels of aspartate aminotransferase were measured at sacrifice to determine liver injury. Pretreatment with BMP-7 significantly improved intestinal transit and significantly decreased intestinal mucosal injury and serum aspartate aminotransferase levels, comparable to animals undergoing IPC. In conclusion, BMP-7 protected against intestinal I/R-induced intestinal and liver injury. Bone morphogenetic protein 7 may be a more logical surrogate to IPC in the prevention of injury in the setting of intestinal I/R.     

Physicochemical properties of perfluorochemical liquids influence ventilatory requirements,pulmonary mechanics,and microvascular permeability during partial liquid ventilation following intestinal ischemia/reperfusion injury

OBJECTIVE: To test the hypothesis that the physicochemical properties of perfluorochemical liquid used in partial liquid ventilation can influence ventilatory requirements, pulmonary mechanics, microvascular permeability, and vasoactive mediator release in the abnormal lung. DESIGN: Prospective, controlled animal study. SETTING: Research laboratory in a university setting.SUBJECTS Male Sprague-Dawley rats: sham and intestinal ischemia/reperfusion injury. INTERVENTIONS: Treatment with perfluorochemical partial liquid ventilation (PLV: PP-5 or H-130) or conventional mechanical ventilation (CMV) over 60 mins of superior mesenteric artery occlusion and 60 mins of reperfusion. MEASUREMENTS AND MAIN RESULTS: Gas exchange, ventilatory requirements, and pulmonary mechanics were measured in vivo. Subsequently, pulmonary vascular resistance, microvascular permeability, and thromboxane were measured by using the isolated perfused lung preparation. PLV with PP-5 required significantly (p <.05) higher positive end-expiratory pressure resulting in increased mean airway pressures and pulmonary vascular resistance in both sham and intestinal ischemia/reperfusion injured animals compared with those treated with CMV or PLV H-130. PLV PP-5 also resulted in significantly (p <.05) lower respiratory compliance and greater microvascular permeability compared with sham animals. Following intestinal ischemia/reperfusion injury, PLV H-130 treated animals had significantly higher (p <.05) respiratory compliance than those treated with PLV PP-5 and a significantly lower (p <.05) intestinal ischemia/reperfusion-mediated increase in microvascular permeability than those treated with CMV or PLV PP-5. Thromboxane levels were significantly higher (p <.01) in injured animals treated with CMV or PLV PP-5 compared with comparably treated shams, were significantly lower (p <.01) in both PLV groups than CMV, and were further attenuated (p <.01) by PLV H-130 compared with PLV PP-5 animals. CONCLUSION: We conclude that PLV with perfluorochemical liquids attenuates pulmonary sequelae resulting from remote organ injury and that the extent of lung protection depends on the physicochemical properties of the perfluorochemical liquids.     

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。     

Measurement of phosphatidylcholine hydroperoxide in mild ischemia-reperfusion injury in rat intestine

In the pathogenesis of intestinal ischemia-reperfusion injury, the measurement of lipid peroxides needs to be established. Sprague-Dawley rat intestines were assessed after 30 minutes of occlusion of the superior mesenteric artery followed by reperfusion at 30, 60, 120, 180, 360 minutes. Grade of the mucosal injury, accumulation of the activated neutrophils and ICAM-1 expression were transiently increased after reperfusion. Two measuring methods of mucosal lipid peroxides using thiobarbituric acid reacting substance (TBARS) and phosphatidylcholine hydroperoxide (PCOOH) were compared. PCOOH level was significantly increased after reperfusion, while the mucosal TBARS level showed no significant change. In conclusion, lipid peroxidation could be detected with high specificity and sensitivity by measuring the mucosal phosphatidylcholine hydroperoxide level.     

肠上皮细胞凋亡与肠缺血损伤及再生修复的实验研究

目的 探讨小肠黏膜缺血损伤及再生修复的特征及规律，以及与肠上皮细胞凋亡的关系。方法 应用小肠缺血再灌注模型，检测小肠缺血及再生修复过程中肠黏膜结构、黏膜隐窝上皮细胞分裂活性及黏膜上皮细胞凋亡的改变。结果 肠缺血再灌注lh，肠黏膜损害加重，黏膜上皮细胞凋亡明显增加，黏膜隐窝上皮细胞分裂活性降低；肠黏膜再生ld、3d组肠黏膜上皮细胞凋亡明显减少，黏膜隐窝上皮细胞分裂活性增加，并逐渐恢复至正常水平，肠黏膜结构逐渐恢复至正常。结论 肠上皮细胞凋亡在肠缺血再灌注损伤及肠再生修复过程中起重要作用。