缺血后处理减轻肠缺血再灌注引起的肝损伤的机制研究

目的：探讨缺血后处理减轻肠缺血再灌注引起的肝损伤的作用机制,为外科防治缺血再灌注损伤提供策略。方法将36只SD大鼠随机分为假手术组（SO组,仅手术显露肠系膜上动脉）、缺血再灌注组（IR组,阻断肠系膜上动脉60min,再灌注120min）、缺血后处理组（IP组,阻断肠系膜上动脉60min后行3个循环的灌注30s/阻断30s,再持续灌注117min）,每组12只。建立模型2h后采集各组大鼠动、静脉血及部分小肠、肝组织,检测血肿瘤坏死因子α（TNF-α）、白细胞介素10（IL-10）、丙氨酸氨基转氨酶（ALT）、天门冬氨酸氨基转移酶（AST）水平,测定血清及肝组织内丙二醛（MDA）、髓过氧化酶（MPO）水平,光学显微镜下观察小肠及肝脏病理学改变,免疫组织化学法检测肝脏组织中核因子κBp65（NF-κBp65）和缺氧诱导因子1α（HIF-1α）的表达变化。结果与SO组比较,IR组小肠、肝脏病理损伤加重,肝组织NF-κBp65和HIF-1α的表达显著升高,血清和肝组织中MDA、MPO水平及血清TNF-α、IL-10、ALT和AST水平升高;与IR组比较,IP组小肠、肝脏损伤减轻,肝组织NF-κBp65表达下降而HIF-1α的表达显著升高,血清和肝组织中MDA、MPO水平及血清TNF-α、ALT和AST水平均显著下降,血清IL-10水平增加,差异均有统计学意义（P＜0.05）。结论缺血后处理可以促进抗炎因子的激活,抑制NF-κB信号通路调控的炎症级联反应,上调HIF-1α的表达,减轻小肠缺血再灌注引起的肝损伤。     

Effects of in vivo freezing and mannitol in intestinal ischaemia-reperfusion injury

PURPOSE: The main purpose of this study was to investigate whether in vivo freezing and mannitol administration can protect the small intestine against ischaemia-reperfusion (I-R) injury. METHODS: Fifty male Sprague-Dawley rats (200-225 g) were divided into 5 groups each containing 10 rats; group SO, sham operation group; group I, mesenteric ischaemia group; group R, ischaemia-reperfusion (I-R); group FR, I-R plus in vivo freezing; group MR, I-R plus mannitol treatment. Intestinal ischaemia for 30 min and reperfusion for 60 min were applied. Ileum specimens were obtained to determine the tissue levels of malondialdehyde (MDA) and histological changes. RESULTS: The mucosal injury scores of group R were significantly higher than those of the group I (P<0.0001). The mucosal injury scores in the groups FR and MR were significantly lower than the group R (P<0.0001 and P<0.0001, respectively). In the group FR, mucosal injury scores were not significantly different from those of group I (P=0.123). However, mucosal injury scores of group MR were significantly less when compared to those of group I (P=0.01). Mean MDA levels of group R were significantly higher than those of the group I (P<0.0001). Mean MDA levels of groups FR and MR were significantly lower than those of group R (P<0.0001 and P<0.0001, respectively). In addition, MDA levels of group FR were significantly higher than those of group MR (P<0.0001). CONCLUSION: In conclusion, these observations suggest that the in vivo freezing of SMA and the pre-treatment with mannitol before reperfusion period may be useful in preventing intestinal reperfusion injury.     

15-F2t-isoprostane在大鼠肠缺血再灌注损伤中的作用

目的 评价异构前列腺素15-F2t-isoprostane在大鼠肠缺血再灌注损伤中的作用.方法 健康雄性SD大鼠32只,体重230 ～ 255 g,采用随机数字表法,将其随机分为4组(n=8):假手术组(S组)、肠缺血再灌注组(I/R组)、血栓烷A2(TXA2)受体拮抗剂SQ-29548组(SQ组)和二甲基亚砜组(DMSO组).采用阻断肠系膜上动脉60 min,再灌注120 min的方法制备肠缺血再灌注损伤模型.SQ组及DMSO组分别于夹闭肠系膜上动脉前30 min腹部皮下注射SQ-29548或二甲基亚砜2μmol/kg.于再灌注120 min时取肠段,观察肠粘膜形态学,并行Chiu评分,取肠粘膜组织,检测髓过氧化物酶(MPO)、超氧化物歧化酶(SOD)活性和丙二醛(MDA)、乳酸(LD)含量;采集动脉血样,检测血清二胺氧化酶( DAO)活性及15-F2t-isoprostane、内皮素-1(ET-1)和血栓烷B2(TXB2)浓度.结果 与S组比较,其余各组Chiu评分、DAO活性、15-F2t-isoprostane及TXB2浓度均升高(P＜0.05),SQ组LD和MDA含量、MPO和SOD活性及ET-1浓度差异无统计学意义(P＞0.05);与I/R组比较,SQ组Chiu评分、LD含量、DAO和MPO活性及ET-1浓度降低,SOD活性升高(P＜0.05).结论 15-F2t-isoprostane可通过激活TXA2受体,增加ET-1生成及促进中性粒细胞在肠粘膜聚集参与大鼠肠缺血再灌注损伤过程.     

Effects of anti-shock agents on the re-opened superior mesenteric artery flow

We investigated intestinal blood circulation after re-opening of a fixed-time occlusion of the superior mesenteric artery (SMA) in rabbits. The SMA root was occluded for 60 minutes, after which blood pressure and SMA flow were monitored for one hundred minutes under the administration with fluid infusion of three anti-shock agents; dopamine, phenoxybenzamine and dexamethasone. The intestinal wall tissue circulation in parallel with SMA flow was also studied. Blood pressure and SMA flow decreased after release of the SMA occlusion (SMAO), as compared those during pre-occlusive time in the control group. Fluid infusion alone did not improve blood pressure and SMA flow. Pre-administration of dexamethasone with fluid infusion improved blood pressure, SMA flow and the survival rate. Phenoxybenzamine with fluid infusion improved SMA flow, despite the low blood pressure. Circulatory damage to the intestinal wall was more extensive than that to SMA flow. These findings suggest that the severity and mortality of SMAO shock was not caused by plasma loss but rather by toxic metabolites and endotoxin from the ischemic intestine.     

Smooth muscle actin as a novel serologic marker of severe intestinal damage in rat intestinal ischemia–reperfusion and human necrotising enterocolitis

Background

Despite emergence of markers of intestinal mucosal damage such as intestinal fatty-acid binding protein (i-FABP), there are no specific markers of damage extending into the muscle layers. We hypothesized that smooth muscle actin (SMA) released from the intestinal muscularis would be detectable in plasma after severe intestinal injury.

Materials and methods

Serial blood samples were collected from rats (n = 10) undergoing intestinal ischemia–reperfusion injury (IRI) and controls (n = 5). Additionally, admission and/or preoperative plasma samples were collected from twelve neonates with necrotizing enterocolitis (NEC), and five age- and weight-matched controls. Plasma ileal fatty-acid binding protein (rat) or i-FABP (human) were measured by enzyme-linked immunosorbent assay, and plasma SMA was detected by western blotting.

Results

Plasma ileal fatty-acid binding protein was low in both the control group and IRI at baseline, but became rapidly elevated in the IRI group even during ischemia. SMA was detected in reperfusion plasma samples of all IRI rats, but in none of the control samples. Plasma i-FABP was higher in infants with NEC than age- and weight-matched controls. Although i-FABP was higher in infants with severe surgical disease compared with focal disease, there was no difference between the operative and nonoperative groups. SMA was detected in the plasma of all four neonates with severe surgical NEC, but not in those with focal disease or those who were successfully conservatively managed.

Conclusions

SMA is detectable in plasma after severe intestinal injury and maybe a clinically useful maker of intestinal muscle damage.     

胆胰和胃冲剂对大鼠急性胰腺炎早期小肠粘膜抗氧化损伤的保护

目的：观察大鼠急性胰腺炎早期肠粘膜损伤及胆胰和胃冲剂对小肠粘膜的保护效应及其可能的机制。方法：选择SD大鼠96只，制作急性胰腺炎模型，并设假手术组和胆胰和胃冲剂治疗组，分别于术后2、6、12、24h检测各组动物小肠粘膜的超氧化物歧化酶（SOD）、丙二醛（MDA）和分泌型免疫球蛋白A（sIgA）的含量。结果：急性胰腺炎各组的SOD、MDA、sIgA含量与假手术组各时段相比有明显差异（P＜0．05）；治疗2h组与急性胰腺炎2h组各指标相比无明显差异（P＞0．05）；治疗6、12、24h组与急性胰腺炎组各时段相比有显著差异（P＜0．05）；结论：急性胰腺炎时可引起肠粘膜损伤，胆胰和胃冲剂能增强肠粘膜对氧自由基的清除力，提高肠粘膜的免疫机能。     

Role of granulocyte-macrophage colony-stimulating factor on apoptosis induced by ischemia-reperfusion in the intestinal epithelium

BACKGROUND: To evaluate the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on ischemia-reperfusion-induced apoptosis in the intestinal epithelium. METHODS: In this study, 50 male Wistar albino rats were used. After midline laparotomy superior mesenteric artery (SMA) was identified only in the sham group, while 60 min of ischemia and 2 h of reperfusion were performed in the control group. In the treatment groups, after 15, 30 and 60 min of ischemia, respectively, 1 microg/kg GM-CSF was administered subcutaneously, followed by 2 h of reperfusion. Malondialdehyde (MDA), campothecin (CAM), an indicator of DNA fragmentation, and histopathology were evaluated in the intestinal mucosa. RESULTS: Tissue MDA levels were found significantly high in all groups at various times of ischemia and 2 h of reperfusion compared with the sham group (p < 0.001). Administration of GM-CSF following 60 min of ischemia caused a significant increase in the MDA levels compared with the control group (6430 +/- 725 vs. 4174 +/- 565 nmol/g protein for jejunum. 7576 +/- 618 vs. 4938 +/- 809 nmol/g protein for ileum, p < 0.05). Intestinal ischemia and reperfusion resulted in a significant increase in tissue CAM levels (p < 0.05). The highest CAM value was found in the group in which 60 min of ischemia and 2 h of reperfusion were performed (50 +/- 3.2 ng/ml for jejunum, 52.8 +/- 2.7 ng/mg for ileum). Compared with the control group, GM-CSF administration following 1 h of ischemia aggravated the tissue injury. CONCLUSIONS: Apoptosis was induced in the small intestine by ischemia-reperfusion. GM-CSF increased the apoptosis of intestinal epithelial cells and exacerbated mucosal injury due to ischemia-reperfusion.     

卡巴胆碱对烧创伤后肠道功能障碍影响的研究

目的观察肠道内给予卡巴胆碱对兔肠部分缺血再灌注(I/R)损伤及重度烧伤患者肠道功能障碍的影响。方法将50只大白兔制成肠部分I/R损伤模型后,随机分为肠部分I/R损伤组(25只)、卡巴胆碱组[25只,于肠系膜上动脉(SMA)阻断后1h肠内注入3g/L卡巴胆碱(3μg/kg)]；另取25只设为假手术组,仅分离SMA,不阻断；取5只作为正常对照组,不致伤,处死后留取标本待测。检测兔SMA阻断前后及肠道内给予卡巴胆碱后肠黏膜的血流量。各致伤组均在处理后2、4、6、8、24、48、72h留取静脉血测定其血浆二胺氧化酶(DAO)活性及D-乳酸和D-木糖含量。并行葡聚糖蓝排出实验,以检测胃肠道吸收功能。同时选择大面积烧伤[烧伤总面积(84±12)%TBSA]患者8例,在患者肠呜音＜2次/min或腹胀明显时,口服1g/L卡巴胆碱(15μg/kg),观察给药后每分钟肠鸣音次数及腹胀情况。结果SMA阻断后肠部分I/R损伤组肠黏膜血流量为(48±6)PU,较正常对照组[(102±5)PU]明显减少,而肠道内注入卡巴胆碱后1h血流量增至(77±3)PU。肠缺血后肠部分I/R损伤组血浆DAO活性及D-乳酸含量开始升高,处理后24h达峰值[(4．63±0．27)U/ml、(7．9±2．4)mg/L],以后逐渐下降,但仍高于正常对照组[(0．89±0．14)U/ml、(2．0±1．1)mg/L,P＜0．05]。卡巴胆碱组的变化基本同肠部分I/R损伤组,但变化幅度较小；而假手术组则无明显变化(P＞0．05)。在给予D-木糖后2h,肠部分I/R损伤组血浆D-木糖含量显著降低,但处理后6h肠部分I/R损伤组及卡巴胆碱组明显升高,以后逐渐下降；假手术组略有波动。SMA处理后2h肠部分I/R损伤组葡聚糖蓝未见排出,处理后6h其运动距离逐渐增加,但处理后24h其运动距离仍明显短于正常值(P＜0．05),48～72h基本恢复正常；卡巴胆碱组注入葡聚糖蓝后即可见其排出,其运动距离明显增加,处理后6h达峰值(43±6)cm,以后逐渐缩短接近正常(28±3)cm。给药前患者肠呜音较弱(1．6±1．1)次/min,给药后10 min明显增强为(6．9±1．7)次/min,30 min时为(8．3±2．4)次/min,给药后1h患者肠鸣音仍较活跃,为(6．1±1．3)次/min。给药后2h患者腹胀明显减轻,其中有6例患者开始排便。结论肠内给予卡巴胆碱可增加兔肠黏膜血流量,改善其肠道运动、吸收、屏障功能；大面积烧伤患者口服卡巴胆碱,可改善其肠道功能障碍。     

P-selectin knockout mice have improved outcomes with both warm ischemia and small bowel transplantation

AIM: To analyze the role of P-selectin in intestinal ischemia and reperfusion injury (IRI) using murine models. METHODS: A model of warm IRI wherein the SMA was occluded for 100 minutes was undertaken in the following groups (10 mice per group): Group 1 (control) wild-type (WT) C57BL6, no treatment; Group 2: 0.4 mg/kg of r-PSGL1-lg 10 minutes before and after clamping; Group 3: PSGL KO mice. Survival was assessed at 7 days; the intestine was assayed for histopathology, apoptosis, myeloperoxidase (MPO), IL1, and TNF. A second model of cold IRI followed by intestinal transplantation (IT) was undertaken in the following groups (two mice per group): Group A WT --> WT: Group B PSGL KO --> WT (1-hour ischemia); Group C: PSGL KO --> WT (2 hour ischemia). Survival only was assessed. RESULTS: Survival was 50% in group 1, 90% in group 2, and 100% in group 3. Graded histopathology and crypt apoptosis demonstrated significantly less injury in groups B and C. MPO was not different between groups. IL1 and TNF were significantly reduce in groups 2 and 3. Following IT, survival was <12 hours in group A, >7 days in group B, and <72 hours in group C. CONCLUSION: This study clearly demonstrates the importance of P-selectin in warm and cold IRI in that the blockade of P-selectin using rPSGL1-lg or the absence of P-selectin using KO mice confers a survival advantage and reduction in tissue injury. The mechanism is unclear but appears to be independent of neutrophil infiltration.     

The role of melatonin in prevention of intestinal ischemia-reperfusion injury in rats

BACKGROUND/PURPOSE: The aim of this study was to determine the effect of melatonin, a hormone that is known as an antioxidant, on the prevention of tissue damage during mesenteric ischemia/reperfusion (I/R). METHODS: A total of 40 young Wistar-albino rats were divided equally into 4 groups with varied treatment. Group 1 was control (sham), group 2 was I/R, group 3 was I/R plus melatonin (10 mg/kg) and group 4 was I/R plus melatonin (20 mg/kg). I/R was realized as follows: after laparatomy, a microvascular atraumatic clip was placed across the superior mesenteric artery (SMA) under general anaesthesia, and it was removed after ischemia for 30 minutes. The first dose of melatonin was applied intraperitoneally at the start of reperfusion. The second and third doses were applied intramuscularly on the first and second day. Only SMA dissection under general anaesthesia was carried out in the control group rats. On the third day of the study all the rats were killed, and their bowels were removed. Malondialdehyde (MDA) levels were assayed as an index of lipid peroxidation reflecting free radical reaction in the intestine. Histopathologic analysis was made using light microscopy in a blind fashion. RESULTS: The levels of tissue MDA were found to be significantly lower in groups 3 and 4 compared with group 2 (P < .05). The MDA levels of group 4 did not differ significantly from that of the control group (P > .05). The histopathologic results were consistent with the MDA levels. CONCLUSION: These results suggest that melatonin has a strong antioxidant effect in preventing intestinal I/R damage, and that this effect is exerted in a dose-dependent manner.     

The sequence of development of intestinal tissue injury after strangulation ischemia and reperfusion

Tissue injury at reperfusion has been reported after partial ischemia. However, previous attempts to demonstrate a component of injury caused by reperfusion after total ischemia have failed. This study was performed to evaluate the hypothesis that in such situations the extent of the tissue injury caused by ischemia itself prevented detection of a reperfusion component. Rats were subjected to near-total intestinal ischemia by means of a hydrostatic pressure clamp that produced preferential venous occlusion (strangulation) for periods from 1 to 90 minutes. Tissue injury was evaluated microscopically by a blinded examiner. Ischemic periods of 20 minutes or less did not induce detectable tissue injury. Longer durations of ischemia caused villous injury: the longer the period of ischemia, the more extensive the tissue injury. However, there was no exacerbation of injury seen after reperfusion, regardless of the duration of ischemia. In a separate series of rats, total arterial occlusion was employed without concomitant venous congestion. Such isolation arterial occlusion of 40 to 60 minutes' duration was followed by a statistically significant exacerbation of tissue injury at reperfusion. Thus total intestinal ischemia may be followed by reperfusion injury if there is no concomitant congestion and if ischemic injury is not too extensive.     

大鼠肝缺血及再灌注所致小肠过氧化损伤及丹参的保护作用

目的 观察大鼠肝缺血再灌注小肠过氧化损伤及丹参预处理的保护作用.方法 首先将SD大鼠随机分为正常对照组(CO组)、假手术组(SO组)、缺血再灌注组(IR组)、丹参预处理组(SM组),分别在肝缺血30、45、60 min时取上段空肠进行大体病理学检测;然后在肝缺血45 min条件下,动物亦随机分为4组(CO组、SO组、IR组、SM组),按再灌注后不同时间(0、3、12、24、72 h)分为5个亚组,每组5只.SM组在阻断第一肝门30 min前经尾静脉推注丹参注射液6 g/kg加生理盐水40 ml/kg,其余各组按40 ml/kg给予生理盐水尾静脉注入,SO组开腹后仅解剖肝门,不钳夹肝蒂.分别在再灌注0、3、12、24、72 h取上段空肠行病理学检查、丙二醛(MDA)含量测定、髓过氧化物酶(MPO)活性测定.结果 空肠黏膜损伤评分随肝缺血时限延长而加重;在肝缺血45 min再灌注不同时限点SM组空肠黏膜损伤较IR组明显减轻,且肠组织MDA含量、MPO活性均低于IR组(P<0.05).结论 肝缺血再灌注所致小肠明显淤血性损伤,MDA含量、MPO活性升高,丹参预处理对肝缺血再灌注所致小肠损伤具有保护作用.     

Ergothioneine modulates proinflammatory cytokines and heat shock protein 70 in mesenteric ischemia and reperfusion injury

BACKGROUND AND AIM: Ergothioneine (EGT) is a natural compound that is synthesized by soil bacteria in fungal substrates and exhibits antioxidant functions in many cell models. The purpose of this study was to investigate the effect of EGT on mesenteric ischemia and reperfusion injury. MATERIALS AND METHODS: Rats were supplemented with or without l-ergothioneine (10 mg/kg/d) for 15 days prior to intestinal ischemia. Animals were subjected to ischemia induced by clamping the superior mesenteric artery for 60 min followed by reperfusion. Serum tumor necrosis factor (TNF)-alpha and interleukin-1beta (IL-1beta) levels, tissue malondialdehide (MDA), myleoperoxidase (MPO), and heat shock protein (HSP) 70 levels, as well as histological findings, were evaluated after 1, 2, and 4 h of reperfusion. RESULTS: Serum TNF-alpha and IL-1beta levels, and tissue MDA and MPO activities at 1, 2 and 4 h after reperfusion in the EGT group, were significantly lower than the control group (P < 0.05). Tissue HSP-70 levels of the study group were significantly greater than the control group at any time point of reperfusion. No significant differences in tissue damage including morphological changes ranging from villous denudation to focal necrosis, ulceration, hemorrhage, and architectural disintegration at 1 and 2 h after reperfusion exist between the two groups; however, after 4 h of reperfusion, the tissue damage based on histopathologic scores by Chiu was considerably lower in the study group (P < 0.05). After 4 h of reperfusion, focal epithelial lifting and occasional areas of denuded villi could be seen in the samples of the treated animals, thus preserving villous height and mucosal architecture. CONCLUSION: EGT attenuates mesenteric ischemia reperfusion injury in rat intestine by increasing tissue HSP-70 and decreasing TNF-alpha, IL-1beta, MDA, and MPO levels. EGT also improves morphological alterations, which occurred after IR injury after prolonged periods of reperfusion.     

Increased plasma malondialdehyde in patients with small intestinal strangulation obstruction

Plasma malondialdehyde (MDA) was evaluated as an index of lipid peroxidation in 20 patients with small intestinal obstruction, with or without strangulation. The gut proved to be strangulated in nine cases--irreversibly in five and reversibly in four--while 11 patients had simple obstruction. The MDA levels in these cases were compared with values obtained from 29 healthy control subjects. The mean MDA level in the control group was 2.3 +/- 0.7 (range 1.5-4.0) mumol/l. In the patients with strangulation obstruction the MDA concentration was 6.7 +/- 1.6 mumol/l, and in those with simple obstruction it was 2.9 +/- 0.5 mumol/l. The difference between the MDA level in strangulation and in the other investigated groups was statistically significant. Values above 4 mumol/l were found in all the patients with intestinal strangulation, whereas those with simple obstruction had lower values. The heightened MDA level in patients with intestinal strangulation may be used for diagnostic purposes.     

Protective effects of glucagon-like peptide 2 on intestinal ischemia-reperfusion rats

Our objective was to evaluate the protective effects of glucagon-like peptide 2 (GLP-2) on intestinal ischemia/reperfusion (I/R) rats. Thirty-two rats were randomly assigned to four experimental groups, each of 8: Group A, sham rats underwent laparotomy only, without superior mesenteric artery (SMA) occlusion; Group B, I/R animals underwent laparotomy and occlusion of the SMA for 60 minutes followed by 120 minutes of reperfusion; Group C, I/R animals underwent intestinal I/R, and received pretreatment with GLP-2 for 3 days preoperatively; and Group D, I/R animals underwent intestinal I/R, received pretreatment with GLP-2 as above, and during the reperfusion phase were injected intravenously with GLP-2. After the reperfusion of intestinal ischemia, samples of intestinal mucosa, mesenteric lymph nodes (MLN) and blood were prepared for determination. In the pretreatment rats with GLP-2 (group C), Chiu's scores, bacterial colony counts, serum D-lactate, intestinal mucosal MDA and ET-1, and serum endotoxin, TNF-alpha and IL-6 were significantly reduced compared with intestinal I/R rats (group B). Administration of GLP-2 during the reperfusion phase following pretreatment (group D) showed further protective effects in comparison with the pretreatment rats (group C). We conclude that treatment with GLP-2 attenuates intestinal I/R injury, reduces bacterial translocation, inhibits the release of oxygen free radicals and ET-1, and may well inhibit the production of proinflammatory cytokines.     

缺血预处理-后处理对大鼠肠缺血再灌注损伤的影响

目的 评价缺血预处理.后处理对大鼠肠缺血再灌注损伤的影响.方法 清洁级成年雄性SD大鼠40只.体重225～275 g,随机分为5组(n=8):假手术组(S组)仅分离肠系膜上动脉(SMA),不夹闭;肠缺血再灌注组(IIR组)采用夹闭SMA 60 min,再灌注60 min的方法制备肠缺血再灌注损伤模型;缺血预处理组(IPr组)夹闭SMA 10 min,再灌注10 min,余同IIR组;缺血后处理组(IPo 组)夹闭SMA 60 min后,再灌注30 s,缺血30 s,反复3次,再灌注60 min;缺血预处理.后处理组(IPr-IPo组)先行缺血预处理,再行缺血后处理,操作过程同IPr组和IPo组.于再灌注60 min时各组取肠粘膜组织,观察肠粘膜形态并行Chiu评分,检测丙二醛(MDA)含量,超氧化物歧化酶(SOD)及髓过氧化物酶(MPO)活性,同时采集动脉血样检测血浆肿瘤坏死因子α(TNF-α)及白细胞介素6(IL-6)浓度.结果 与S组比较,其余各组Chiu评分、MDA含量、MPO活性、血浆TNF-α与IL-6浓度升高,SOD活性降低(P<0.05).与IIR组比较,IPr组、IPo组及IPr-IPo组Chiu评分、MDA含量、MPO活性、血浆TNF-α和IL-6浓度降低.SOD活性升高(P<0.01).与IPr组和IPo组比较,IPr-IPo组Chiu评分和MDA含量降低,SOD活性升高(P<0.05).IPr组与IPo组各指标比较差异无统计学意义(P>0.05).结论 缺血预处理-后处理可减轻大鼠肠缺血再灌注损伤,较单独应用时效果好.     

Human breast milk-derived exosomes protect against intestinal ischemia and reperfusion injury in neonatal rats

BackgroundIntestinal ischemia and reperfusion (IR) injury like that seen in midgut volvulus can be life-threatening in the pediatric population. Human breast milk-derived exosomes (HMDEs) can prevent intestinal inflammation in experimental necrotizing enterocolitis and other intestinal diseases. The aim of this study is to investigate the effects of HMDEs on intestinal damage related to IR injury.MethodsExosomes were isolated from human breast milk by ultracentrifugation then confirmed by Nanoparticle tracking analysis and detection of exosome membrane markers. 2-weeks old Sprague Dawley rats were randomly divided into 4 groups: a) Sham (n = 8) with laparotomy alone, b) Sham with HMDEs administration by gavage (n = 8), c) Intestinal IR injury (n = 8) by occlusion of the superior mesenteric artery (SMA) for 30 min followed by reperfusion, and d) Intestinal IR by SMA occlusion with HMDEs administration by gavage (n = 8). Six hours after laparotomy, animals were euthanized, and the ilea (10 cm to cecum) were harvested. Mucosal injury was scored histologically. The intestines were further examined for inflammatory cytokine TNFα, and epithelial proliferation marker Ki67.ResultsCompared to sham, the small intestine of IR rats had more intestinal damage, increased expression of inflammatory cytokine TNFα and decreased intestinal proliferation. HMDEs significantly counteracted all these changes.ConclusionsHuman breast milk-derived exosomes protect the intestine against damage by IR injury. This beneficial effect is associated with decreased intestinal inflammation and enhanced epithelial proliferation. This study implicates the potential novel application of HMDEs in preventing intestinal damage in infants with intestinal IR injury.     

Free Radical Scavenging Activity of Fullerenol on the Ischemia-reperfusion Intestine in Dogs

Fullerenol, a water-soluble C₆₀-fullerene derivative, has been demonstrated to have the capability to scavenge free radicals in vitro and in vivo. The purpose of this study was to investigate whether fullerenol can scavenge the free radicals that are massively induced during ischemia-reperfusion (I/R) injury of the small intestine, either preventively or therapeutically. Clamping the superior mesenteric artery and vein for 60 minutes to induce I/R injury was performed on male mongrel dogs. Thirty dogs were divided into three groups (10 in each): The control (C) group received no medication; the preventive (P) group received fullerenol (1 mg/kg) intravenously 30 minutes before ischemia; the therapeutic (T) group received the same dose of fullerenol immediately after reperfusion. This study was an experimental randomized trial. Intestinal segments were obtained 10, 20, 30, and 60 minutes after reperfusion; and blood samples and specimens of major organs were taken 60 minutes after reperfusion. Concentrations of lipid peroxidation products, including conjugated diene (CD) and malondialdehyde (MDA), and the level of glutathione (GSH) in intestinal tissue were determined. Serum indicators of liver and renal function were measured. Histologic examination of the small intestine and major organs were also performed. A significant increase in intestinal MDA and CD contents was detected at 30 and 60 minutes after reperfusion. The tissue GSH content, in contrast, was decreased 60 minutes after reperfusion. Administration of fullerenol diminished these changes both preventively and therapeutically. Liver and renal functions were within normal limits in all groups. Moreover no obvious histopathologic additional damage could be found in either the P or the T group. It is suggested that fullerenol can be considered a powerful scavenger for the free radicals induced by I/R injury of the small intestine.     

The use of intraperitoneal xenon for early diagnosis of acute mesenteric ischemia

We evaluated the technique of intraperitoneal use of xenon Xe 133, previously described for the diagnosis of early intestinal strangulation obstruction in rats and dogs, for the recognition of acute mesenteric vascular occlusion in these animals. 133Xe was injected intraperitoneally into five groups of six rats: control, sham operation, superior mesenteric artery (SMA) ligation, superior mesenteric vein ligation, and portal vein ligation. Residual gamma-activity was monitored by external counting and camera imaging. At 30 minutes after injection, the activity was significantly higher in the rats from the three groups with vascular ligation than in the control and sham operation animals (P less than 0.001). gamma-Camera images reflected these findings, with positive images only in the rats that underwent vascular ligation. "Blinded" readings of the 30 sets of scans confirmed the diagnostic accuracy of the images. Results were essentially the same in a second series of experiments in eight control dogs and six dogs with balloon occlusion of the SMA. Concentrations of isotope in ischemic intestine ranged from 10(3) to 10(5) times the levels in adjacent normal bowel. These levels and the positive images appeared early, prior to the development of tissue necrosis. The intraperitoneal use of 133Xe therefore continues to show promise for the recognition of patients with early intestinal ischemia.     

Ischaemic preconditioning improves microvascular perfusion and oxygenation following reperfusion injury of the intestine

BACKGROUND: Ischaemia-reperfusion (IR) injury of the intestine occurs commonly during abdominal surgery. Ischaemic preconditioning (IPC) provides a way of protecting the organ from damage inflicted by IR. This study was designed to evaluate the beneficial effect of IPC, focusing on the intestinal microcirculation and oxygenation in intestinal IR injury. METHODS: Rats were allocated to three groups. Animals in the IR and IPC groups underwent 30 min of intestinal ischaemia followed by 2 h of reperfusion. In the IPC group this was preceded by 10 min of ischaemia and 10 min of reperfusion. Animals in the third group underwent laparotomy but no vascular occlusion. Intestinal microvascular perfusion, oxygenation and portal venous blood flow (PVF) were monitored continuously. At the end of the reperfusion period, blood samples were obtained for measurement of lactate dehydrogenase (LDH) and biopsies of ileum for histological evaluation. RESULTS:: IPC improved intestinal microvascular perfusion and tissue oxygenation significantly at the end of the reperfusion period (P < 0.001). PVF improved significantly in the IPC compared with the IR group (P = 0.005). The serum LDH concentration was significantly lower in the IPC than the IR group (mean(s.e.m.) 667.1(86.8) versus 1973.8(306.5) U/l; P < 0.001) Histological examination showed that ileal mucosa was significantly less injured in the IPC group. CONCLUSIONS: This study demonstrated that IPC improves intestinal microvascular perfusion and oxygenation.