Endothelial Cell-Derived von Willebrand Factor Is the Major Determinant That Mediates von Willebrand Factor-Dependent Acute Ischemic Stroke by Promoting Postischemic Thrombo-Inflammation.

OBJECTIVE: von Willebrand factor (VWF), which is synthesized in endothelial cells and megakaryocytes, is known to worsen stroke outcome. In vitro studies suggest that platelet-derived VWF (Plt-VWF) is biochemically different from the endothelial cell-derived VWF (EC-VWF). However, little is known about relative contribution of different pools of VWF in stroke. APPROACH AND RESULTS: Using bone marrow transplantation, we generated chimeric Plt-VWF mice, Plt-VWF mice that lack ADAMTS13 in platelets and plasma (Plt-VWF/Adamts13(-/-)), and EC-VWF mice to determine relative contribution of different pools of VWF in stroke. In brain ischemia/reperfusion injury model, we found that infarct size and postischemic intracerebral thrombo-inflammation (fibrin(ogen) deposition, neutrophil infiltration, interleukin-1ß, and tumor necrosis factor-α levels) within lesions were comparable between EC-VWF and wild-type mice. Infarct size and postischemic thrombo-inflammation were comparable between Plt-VWF and Plt-VWF/Adamts13(-/-) mice, but decreased compared with EC-VWF and wild-type mice (P<0.05) and increased compared with Vwf(-/-) mice (P<0.05). Susceptibility to FeCl3 injury-induced carotid artery thrombosis was comparable between wild-type and EC-VWF mice, whereas Plt-VWF and Plt-VWF/Adamts13(-/-) mice exhibited defective thrombosis. Although most of the injured vessels did not occlude, slope over time showed that thrombus growth rate was increased in both Plt-VWF and Plt-VWF/Adamts13(-/-) mice compared with Vwf(-/-) mice (P<0.05), but decreased compared with wild-type or EC-VWF mice. CONCLUSIONS: Plt-VWF, either in presence or absence of ADAMTS13, partially contributes to VWF-dependent injury and postischemic thrombo-inflammation after stroke. EC-VWF is the major determinant that mediates VWF-dependent ischemic stroke by promoting postischemic thrombo-inflammation.

TLR4-HMGB1-, MyD88- and TRIF-dependent signaling in mouse intestinal ischemia/reperfusion injury.

AIM: To characterize high-mobility group protein 1-toll-like receptor 4 (HMGB1-TLR4) and downstream signaling pathways in intestinal ischemia/reperfusion (I/R) injury. METHODS: Forty specific-pathogen-free male C57BL/6 mice were randomly divided into five groups (n = 8 per group): sham, control, anti-HMGB1, anti-myeloid differentiation gene 88 (MyD88), and anti-translocating-chain-associating membrane protein (TRIF) antibody groups. Vehicle with the control IgG antibody, anti-HMGB1, anti-MyD88, or anti-TRIF antibodies (all 1 mg/kg, 0.025%) were injected via the caudal vein 30 min prior to ischemia. After anesthetization, the abdominal wall was opened and the superior mesenteric artery was exposed, followed by 60 min mesenteric ischemia and then 60 min reperfusion. For the sham group, the abdominal wall was opened for 120 min without I/R. Levels of serum nuclear factor (NF)-κB p65, interleukin (IL)-6, and tumor necrosis factor (TNF)-α were measured, along with myeloperoxidase activity in the lung and liver. In addition,morphologic changes that occurred in the lung and intestinal tissues were evaluated. Levels of mRNA transcripts encoding HMGB1 and NF-κB were measured by real-time quantitative PCR, and levels of HMGB1 and NF-κB protein were measured by Western blot. Results were analyzed using one-way analysis of variance. RESULTS: Blocking HMGB1, MyD88, and TRIF expression by injecting anti-HMGB1, anti-MyD88, or anti-TRIF antibodies prior to ischemia reduced the levels of inflammatory cytokines in serum; NF-κB p65: 104.64 ± 11.89, 228.53 ± 24.85, 145.00 ± 33.63, 191.12 ± 13.22, and 183.73 ± 10.81 (P < 0.05); IL-6: 50.02 ± 6.33, 104.91 ± 31.18, 62.28 ± 6.73, 85.90 ± 17.37, and 78.14 ± 7.38 (P < 0.05); TNF-α, 43.79 ± 4.18, 70.81 ± 6.97, 52.76 ± 5.71, 63.19 ± 5.47, and 59.70 ± 4.63 (P < 0.05) for the sham, control, anti-HMGB1, anti-MyD88, and anti-TRIF groups, respectively (all in pg/mL).Antibodies also alleviated tissue injury in the lung and small intestine compared with the control group in the mouse intestinal I/R model. The administration of anti-HMGB1, anti-MyD88, and anti-TRIF antibodies markedly reduced damage caused by I/R, for which anti-HMGB1 antibody had the most obvious effect. CONCLUSION: HMGB1 and its downstream signaling pathway play important roles in the mouse intestinal I/R injury, and the effect of the TRIF-dependent pathway is slightly greater.

Role of calreticulin mutations in the aetiological diagnosis of splanchnic vein thrombosis.

BACKGROUND & AIMS: Myeloproliferative neoplasms are the most common aetiological cause of splanchnic vein thrombosis (SVT). In these patients, the JAK2V617F mutation has facilitated the diagnosis of an underlying myeloproliferative neoplasm (MPN). Recently, somatic mutations of the calreticulin (CALR) gene have been identified in MPN patients lacking the JAK2 mutation. The aim of the present study was to ascertain whether CALR mutations could also play a role in the diagnosis of masked MPN in SVT. METHODS: We included 209 patients with SVT (140 with PVT and 69 with Budd-Chiari syndrome) who had a complete aetiological diagnostic work-out. They were investigated for CALR mutations. RESULTS: CALR mutations were found in 4 of the 209 patients (1.9%). They represented 5.4% of patients with an underlying MPN of whom all had already been diagnosed with a MPN using conventional criteria including bone marrow biopsy findings. CONCLUSIONS: In the screening of underlying MPNs in patients with SVT, given its high frequency in these disorders, the JAK2 mutation must be evaluated first and, if negative, CALR mutations should also be investigated. This approach would increase the diagnostic yield of masked MPNs by reducing the need for additional studies.

Intraperitoneal metabolic consequences of supraceliac aortic balloon occlusion in an experimental animal study using microdialysis.

BACKGROUND: To investigate the effects of supraceliac aortic balloon occlusion (ABO) and superior mesenteric artery (SMA) occlusion on abdominal visceral metabolism in an animal model using intraperitoneal microdialysis (IPM) and laser Doppler flowmetry. METHODS: A total of 9 pigs were subjected to ABO and 7 animals were subjected to SMA occlusion for 1 hour followed by 3 hours of reperfusion. Seven animals served as controls. Hemodynamic data, arterial blood samples, urinary output, and intestinal mucosal blood flow (IBF) were followed hourly. Intraperitoneal (i.p) glucose, glycerol, lactate, and pyruvate concentrations and lactate-to-pyruvate (l/p) ratio were measured using IPM. RESULTS: Compared with the baseline, ABO reduced IBF by 76% and decreased urinary output. SMA occlusion reduced IBF by 75% without affecting urinary output. ABO increased the i.p l/p ratio from 18 at baseline, peaking at 46 in early reperfusion. SMA occlusion and reperfusion tended to increase the i.p l/p ratio, peaking at 36 in early reperfusion. ABO increased the i.p glycerol concentration from 87 µM at baseline to 579 µM after 3 hours of reperfusion. SMA occlusion and reperfusion increased the i.p glycerol concentration but to a lesser degree. CONCLUSIONS: Supraceliac ABO caused severe hemodynamic, renal, and systemic metabolic disturbances compared with SMA occlusion, most likely because of the more extensive ischemia-reperfusion injury. The intra-abdominal metabolism, measured by microdialysis, was affected by both ABO and SMA occlusion but the most severe disturbances were caused by ABO. The i.p l/p ratios and the glycerol concentrations increased during ischemia and reperfusion and may serve as markers of these events and indicate anaerobic metabolism and cell damages respectively.

MiR-874 promotes intestinal barrier dysfunction through targeting AQP3 following intestinal ischemic injury.

Intestinal ischemic injury is a significant clinical problem arising from diseases or as a complication of abdominal surgery. Our previous study showed aquaporin 3 is involved in intestinal barrier impairment. Here, we revealed that intestinal ischemia induced a time-dependent increase of miR-874 expression and a time-dependent decrease of AQP3 expression, and the level of miR-874 expression was inversely related to AQP3 protein expression. In addition, miR-874 promoted the paracellular permeability in vitro through targeting 3'UTR of AQP3. Two of the tight junction proteins, Occludin and Claudin-1, were found to be involved in miR-874-induced intestinal barrier dysfunction.

Effects of exogenous vasoactive intestinal peptide on mesenteric lymph pathway during early intestinal ischemia-reperfusion injury in rats.

Mesenteric lymph pathway serves as the primary route by which gut injury leads to systemic inflammation and distant organ injury. The inflammation of the intestinal tract is partially mediated by vasoactive intestinal peptide (VIP). Therefore, the aim of this study was to test whether exogenous VIP affects mesenteric lymph pathway during early intestinal ischemia-reperfusion (IIR) injury. Rats were randomized into control, control+VIP, IIR and IIR+VIP groups. The observation of mesenteric lymph flow was carried out by cannulation of mesenteric lymphatics. The distribution of in vivo lymphocyte trafficking was performed by (51)Cr labeled lymphocytes and was measured by γ-counter. Endotoxin concentration was assayed using the limulus test kit and TNF-α level was detected by ELISA. When IIR injury treated with VIP, the volumes of lymph flow increased by 80%, which caused the number of lymphocytes exiting in mesenteric lymphatic increased by 50% while the proportion of (51)Cr-lymphocytes in Peyer's patches, intestinal effector tissues, mesenteric nodes, large intestine, stomach decreased by 58%, 51%, 58%, 63%, 64% respectively at the 6th h after reperfusion following intestinal ischemia. Meanwhile, endotoxin and TNF-α levels in intestinal lymph decreased by 51% and 83%. These results suggest that exogenous VIP ameliorates IIR induced splanchnic organ damage via inhibition of toxic mediators reaching systemic circulation and reinforcement of the effective immune responses in gut-associated lymphoid tissues (GALT).

Pentoxifylline protects the small intestine after severe ischemia and reperfusion.

OBJECTIVES: Pentoxifylline, a methylxanthine derivative with significant hemorheologic properties, is used for claudication in patients with peripheral vascular disease, and experimentally for ischemic injury to organs because of its antioxidant and antiinflammatory effects. We used a rat model of severe small intestinal ischemia and reperfusion to determine the ability of pentoxifylline in improving survival, molecular response, and pathological protection. MATERIALS AND METHODS: We used 6 groups of male Wistar rats (n=25 each). The superior mesenteric artery was occluded for 120 minutes. Laboratory and tissue studies were done on 5 animals, 1 hour after reperfusion, and animal survival was assessed at 7 days. There were 2 control groups that received normal saline, either before ischemia or during reperfusion. The 4 treated groups received pentoxifylline 1 or 10 mg/kg at the same times mentioned above. Laboratory studies included measuring serum lactic acid dehydrogenase, tumor necrosis factor-α, interleukin-1ß, and interleukin-6.Intestinal tissue malondialdehyde and myeloperoxidase in small intestine tissue also were measured. Histology and laser vascular blood flow at baseline and reperfusion were obtained, and survival was determined 7 days after ischemia. RESULTS: A significant survival benefit in the animals treated with 10 mg/kg of pentoxifylline at reperfusion was noted. This coincided with a reduction in biochemical markers of cell damage - specifically, serum lactic acid dehydrogenase, and tissue malondialdehyde, ischemia, and reperfusion. Additionally, we saw decreased levels of tumor necrosis factor-α, interleukin-1ß, and interleukin-6. Improved postreperfusion blood flow shown by laser Doppler technology also was seen in the treated groups. Histologically, we observed less neutrophil infiltration in the intestine of ischemic-treated rats. Also seen in the control animals were increased necrotic lesions in the microvilli with a higher presence of lysozyme in the Paneth cells. Survival was significantly better at 7 days (70% vs 40%) when we compared the pentoxifylline group treated at reperfusion (10 mg/kg) to the ischemic controls. CONCLUSIONS: Pentoxifylline had a significant protective effect on severely ischemic bowel when administered during reperfusion at a dosage of 10 mg/kg. Better survival, improved histology, and molecular response should urge consideration of the consideration of applying these findings in some general surgery and transplant conditions.

Ischemic postconditioning attenuate reperfusion injury of small intestine: impact of mitochondrial permeability transition.

BACKGROUND: Ischemic postconditioning (IPoC) modulates the reperfusion maneuver to mitigate ischemia-reperfusion (I/R) injury. This study aims to investigate the effects and protective mechanism of IPoC on intestinal I/R injury. METHODS: Intestinal I/R was induced by occluding the superior mesenteric artery for 30 min followed by reperfusion for 60 min on male Wistar rats. IPoC was elicited by three cycles of 30-sec reperfusion and reocclusion of superior mesenteric artery at the initiation of reperfusion. Carboxyatractyloside (CATR), a mitochondrial permeability transition pore (mPTP) opener, and N-methyl-4-isoleucine cyclosporine (NIM811), an mPTP inhibitor, were administered separately in selected groups. The serum and intestinal sections were collected for analysis. RESULTS: IPoC and the administration of NIM811 significantly diminished the expression of intestinal-type fatty acid-binding protein and lactate dehydrogenase (3427±236.8 U/L for I/R, 1190.5±36.7 U/L for IPoC, 1399.3±295.6 U/L for I/R+NIM811, and 2002±370.9 IU/L for IPoC+CATR) in portal blood, the release of cytosolic cytochrome c, and the cleaved caspase 9 expression in intestinal mucosa after intestinal I/R injury (P<0.05). Histopathologically, IPoC and NIM811 mitigated mucosal damage after I/R as well (Chiu's score, 3.8±0.4 for I/R, 0.2±0.2 for IPoC, 0.4±0.2 for I/R+NIM811, and 4.2±0.2 for IPoC+CATR; apoptotic index, 59.5%±4.6% for I/R, 15.7%±15.7% for I/R+IPoC, 3.5%±3.5% for I/R+NIM811, and 67.1%±9.3% in IPoC+CATR). CATR negated the protection conferred by IPoC. CONCLUSIONS: IPoC and NIM811 attenuate intestinal I/R injury. The addition of CATR negated the effects of IPoC, indicating that the protective mechanism of IPoC was associated with the modulation of mPTP opening.

Analysis of exhaled volatile compounds following acute superior mesenteric artery occlusion in a pilot rat study.

BACKGROUND: Prompt diagnosis and treatment of acute mesenteric ischemia (AMI) requires a high index of suspicion for timely management. Poor clinical outcomes and delays in surgical treatment are demonstrated even in modern clinical series. Recognition of exhaled volatile organic compounds (VOCs) specific to AMI may facilitate early detection and diagnosis and improve patient outcomes. METHODS: Adult Wistar rats (n = 5) were intubated and anesthetized, and control tracheostomy breath samples were collected using Tedlar gas sample bags. Intestinal ischemia was induced by placing an occlusive clip across the superior mesenteric artery, and breath samples were collected after 1 hour of intestinal ischemia and after 15 minutes of intestinal reperfusion. Gas chromatography was used to identify and measure levels of VOCs obtained, and measured retention indices were compared with known values in the Kovats retention index database. RESULTS: Multiple retention indices (n = 41) were noted on gas chromatography, representing a variety of VOCs detected. Z,Z-farnesol (C15H26O), an isoprenoid, was the only compound detected that was undetectable during the control phase (median = 0 cts/sec) but which significantly elevated during the ischemic (median = 34 cts/sec, range = 25-37) and reperfusion (median = 148 cts/sec, range = 42-246) phases. Three other isoprenoid compounds (E,E-alpha-farnesene, germacrene A, and Z,Z-4,6,8-megastigmatriene) were also detected in all five animals, but their levels did not differ significantly between control, ischemic, and reperfusion phases. CONCLUSIONS: This pilot study demonstrates the feasibility of analyzing exhaled VOCs using a novel rat model for AMI. These findings may be useful for the development and identification of similar assays for the rapid diagnosis of AMI.

Carbon monoxide liberated from CO-releasing molecule (CORM-2) attenuates ischemia/reperfusion (I/R)-induced inflammation in the small intestine.

CORM-released CO has been shown to be beneficial in resolution of acute inflammation. The acute phase of intestinal ischemia-reperfusion (I/R) injury is characterized by oxidative stress-related inflammation and leukocyte recruitment. In this study, we assessed the effects and potential mechanisms of CORM-2-released CO in modulation of inflammatory response in the small intestine following I/R-challenge. To this end mice (C57Bl/6) small intestine were challenged with ischemia by occluding superior mesenteric artery (SMA) for 45 min. CORM-2 (8 mg/kg; i.v.) was administered immediately before SMA occlusion. Sham operated mice were injected with vehicle (0.25% DMSO). Inflammatory response in the small intestine (jejunum) was assessed 4 h following reperfusion by measuring tissue levels of TNF-alpha protein (ELISA), adhesion molecules E-selectin and ICAM-1 (Western blot), NF-kappaB activation (EMSA), along with PMN tissue accumulation (MPO assay) and leukocyte rolling/adhesion in the microcirculation of jejunum (intravital microscopy). The obtained results indicate that tissue levels of TNF-alpha, E-selectin and ICAM-1 protein expression, activation of NF-kappaB, and subsequent accumulation of PMN were elevated in I/R-challenged jejunum. The above changes were significantly attenuated in CORM-2-treated mice. Taken together these findings indicate that CORM-2-released CO confers anti-inflammatory effects by interfering with NF-kappaB activation and subsequent up-regulation of vascular pro-adhesive phenotype in I/R-challenged small intestine.

[Hepato-renal syndrome and problem of protein-energy metabolism correction during urgent surgery of the abdominal organs].

Early connecting of hardware detoxification methods allow more efficient use of amino acid preparations for action. The use of efferent technology provides a full correction of protein and energy metabolism in the immediate surgical patients with complicated diseases of the abdominal cavity. This will reduce bed-day in patient and surgical mortality.

Immediate but not delayed postconditioning during reperfusion attenuates acute lung injury induced by intestinal ischemia/reperfusion in rats: comparison with ischemic preconditioning.

BACKGROUND: A previous study has shown that brief period of repetitive superior mesenteric artery (SMA) occlusion and reperfusion applied at the onset of reperfusion, ischemic postconditioning (IPo), attenuates intestinal injury after intestinal ischemia/reperfusion (II/R). This study tested the hypothesis that IPo would attenuate II/R-induced acute lung injury, which is comparable to ischemic preconditioning (IPC) and the brief period of postconditioning applied at the onset of reperfusion is critical to pulmonary protection by IPo. METHODS: Rat II/R injury was produced by clamping SMA for 60 min followed by 60 min of reperfusion. The rats were randomly allocated into one of five groups based upon the intervention (n = 8): sham operation (Sham): sham surgical preparation including isolation of the SMA without occlusion was performed; Injury: there was no intervention either before or after SMA occlusion; ischemia preconditioning (IPC): the SMA was occluded for 10 min followed by 10 min of reperfusion before prolonged occlusion; ischemia postconditioning (IPo): three cycles of 30 sec reperfusion-30 sec reocclusion were imposed immediately upon reperfusion (3 min total intervention); delayed postconditioning: clamping was completely released for full reperfusion for 3 min (the duration of the IPo algorithm), after which three cycles of 30 sec occlusion and reperfusion were applied. RESULTS: Histologic results showed severe damage in rat lungs in the injury group evidenced by increased lung wet/dry weight ratio and pulmonary permeability index, which was accompanied by increases in the levels of plasma TNFalpha and IL-6, the pulmonary malondialdehyde (MDA), and the pulmonary myeloperoxidase (MPO) activity and a decrease in superoxide dismutase (SOD) activity. IPo, not delayed IPo, could significantly attenuate lung injury and improve the above variables, which was comparable to IPC. CONCLUSIONS: IPo at onset of reperfusion reduces acute lung injury induced by II/R, which may be mediated, in part, by inhibiting oxidant generation, neutrophils filtration, and proinflammatory mediators releases. The early period of reperfusion in the rat model is critical to pulmonary protection by IPo. IPo may improve outcome in clinical conditions associated with II/R.

The correlation of the D-dimer test and biphasic computed tomography with mesenteric computed tomography angiography in the diagnosis of acute mesenteric ischemia.

BACKGROUND: Early diagnosis is the main factor to improve the outcome of acute mesenteric ischemia (AMI). The goal of this study was to assess the correlation of the D-dimer test and biphasic computed tomography (CT) with mesenteric CT angiography for the diagnosis of AMI. METHODS: Selected consecutive patients with a clinical suspicion of AMI were admitted to the study. Blood samples were taken before biphasic CT with mesenteric CT angiography examination. RESULTS: The sensitivity and specificity values of biphasic CT with mesenteric CT angiography were 92.9% and 89.5%, respectively. The sensitivity and specificity of D-dimer testing for the diagnosis of AMI were 94.7% and 78.6%, respectively. D-dimer levels higher than 3.17 microg fibrinogen equivalent units/mL were more specific (P < .0001) and acted similarly to the biphasic CT with mesenteric CT angiography in the diagnosis of AMI. CONCLUSIONS: In the setting of early diagnosis of AMI, the D-dimer test may improve our ability to diagnose patients in whom we cannot use multidetector row CT with CT angiography.

Intestinal ischemia/reperfusion-induced bacterial translocation and lung injury in atherosclerotic rats with hypoadiponectinemia.

BACKGROUND: Intestinal ischemia/reperfusion causes intestinal mucosal injury, which may result in bacterial translocation (BT) and multiple organ failure. Lung injury is a common complication after intestinal ischemia/reperfusion. Adiponectin is an antiinflammatory adipokine, and it plays an important role in the development of metabolic syndrome in hypoadiponectinemia. In atherosclerosis with hypoadiponectinemia, BT also may aggravate injuries induced by intestinal ischemia/reperfusion. METHODS: Wistar rats were divided into 3 groups: Normal group (normal diet), Chol group (2% high cholesterol diet), and Chol+1400W group (Chol group plus 1400W, an inducible nitric oxide [iNOS] inhibitor, at 1 mg/kg intraperitoneally 30 minutes preoperatively). The serum concentrations of lipids and adiponectin and vascular responses were measured. After midline laparotomy (time, T0), the superior mesenteric artery was occluded with a microvascular clamp for 30 minutes, followed by 360 minutes of reperfusion (T1). Intestinal injury was assessed from microcirculatory flow, histology, serum diamine oxidase activity, and permeability. Lung injury was assessed by histology, pulmonary permeability index (PPI), and wet-to-dry lung weight (W/D) ratio. Intestinal and lung nitric oxide (NO) concentrations were also measured. BT was assessed by serum peptidoglycan (PG) concentration. RESULTS: The Chol and Chol+1400W groups developed hyperlipidemia and hypoadiponectinemia; the 2 groups also had vascular endothelial dysfunction without histological changes, indicating early atherosclerosis. These groups also showed poor recovery of intestinal microcirculatory flow at T1. The serum diamine oxidase activity, histological intestinal damage, and permeability were elevated at T1 in the Chol group; however, these findings were not significant in the Normal and Chol+1400W groups. Histological lung damage and lung PPI and W/D ratio were increased only in the Chol group. Intestinal and lung NO concentrations were significantly elevated at T1 in the Chol group. The serum PG concentration was elevated significantly in the Chol group. CONCLUSION: In atherosclerotic rats with hypoadiponectinemia, intestinal microcirculatory flow does not recover adequately after intestinal ischemia/reperfusion because of endothelial dysfunction. Atherosclerosis with hypoadiponectinemia increased the incidence of BT further by aggravating intestinal mucosal injury and, moreover, it aggravated lung injury. Although inhibition of iNOS does not lead to adequate recovery of intestinal microcirculatory flow, it reduces injury by decreasing the amount of NO derived from high enzymatic iNOS activity in the intestine.

Effects of pentoxifylline and n-acetylcysteine on injuries caused by ischemia and reperfusion of splanchnic organs in rats.

AIM: Occlusion and reperfusion of splanchnic arteries cause local and systemic changes due to the release of cytotoxic substances and the interaction between neutrophils and endothelial cells. This study evaluated the role of pentoxifylline (PTX) and n-acetylcysteine (NAC) in the reduction of ischemia, reperfusion shock and associated intestinal injury. METHODS: Sixty rats were divided into 6 groups of 10 animals. Rats in three groups underwent mesenteric ischemia for 30 minutes followed by 120 minutes of reperfusion, and were treated with saline (SAL-5 mL/kg/h), pentoxifylline (PTX-50 mg/kg) or n-acetylcysteine (NAC-430 mg/kg/h). The other 3 groups underwent sham ischemia and reperfusion (I/R) and received the same treatments. Hemodynamic, biochemical and histological parameters were evaluated. RESULTS: No significant hemodynamic or intestinal histological changes were seen in any sham group. No histological changes were found in the lung or liver of animals in the different groups. There was a progressive decrease in mean arterial blood pressure, from mean of 111.53 mmHg (30 minutes of ischemia) to 44.30+/-19.91 mmHg in SAL-I/R, 34.52+/-17.22 mmHg in PTX-I/R and 33.81+/-8.39 mmHg in NAC-I/R (P<0.05). In all I/R groups, there was a progressive decrease in: aortic blood flow, from median baseline of 19.00 mL/min to 2.50+/-5.25 mL/min in SAL-I/R; 2.95+/-6.40 mL/min in PTX-I/R and 3.35+/-3.40 mL/min in NAC-I/R (P<0.05); in the heart rate, from mean baseline of 311.74 bpm to 233.33+/-83.88 bpm in SAL-I/R, 243.20+/-73.25 bpm in PTX-I/R and 244.92+/-76.05 bpm in NAC-I/R (P<0.05); and esophageal temperature, from mean baseline of 33.68 degrees C to 30.53+/-2.05 degrees C in SAL-I/R, 30.69+/-2.21 degrees C in PTX-I/R and 31.43+/-1.03 degrees C in NAC-I/R (P<0.05). In the other hand, there was an attenuation of mucosal damage in the small intestine of the animals receiving PTX, and only in the ileum of the animals receiving NAC. No changes were found in ileum or plasma malondialdehyde levels in any group. CONCLUSIONS: PTX was more efficient in reducing histological lesions than NAC, but neither treatment prevented hemodynamic changes during splanchnic organs I/R.

Time-dependent alterations in serum NO concentration after oral administration of L-arginine, L-NAME, and allopurinol in intestinal ischemia/reperfusion.

OBJECTIVE: To study the effect of oral administration of a nitric oxide (NO) donor L-arginine (L-Arg), a NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) and an inhibitor of xanthine oxidase, allopurinol (Allo), on serum NO concentration and catalase activity after intestinal ischemia/reperfusion (I/R) in rats. METHODS: Male Wistar rats receivedper os L-Arg (800 mg/kg) or L-NAME (50 mg/kg) or Allo (100 mg/kg) 24 hrs, 12 hrs and 1 hr before underwent 1 hr occlusion of superior mesenteric artery followed by 1 hr of reperfusion (L-Arg(IR1), L-NAME(IR1) and Allo(IR1) respectively) or 1 hr occlusion followed by 8 hrs of reperfusion (L-Arg(IR8), L-NAME(IR8) and Allo(IR8) respectively). There was one group underwent 1 hr occlusion (I), a group underwent 1 hr occlusion followed by 1 hr reperfusion (IR1), a group subjected to 1 hr occlusion followed by 8 hrs of reperfusion (IR8) and a last group that served as control (C). Serum NO concentration and catalase activity were measured. RESULTS: After 1 hr of reperfusion serum NO concentration was elevated in IR1 and L-Arg(IR1) groups compared with group C but not in L-NAME(IR1) and Allo(IR1) group. Catalase activity was enhanced in L-NAME(IR1) group. Interestingly, serum NO concentration was increased after 8 hrs of reperfusion in all groups (IR8, L-Arg(IR8), L-NAME(IR8) and Allo(IR8)) compared with control while catalase activity did not show significant difference in any group. CONCLUSIONS: The results of the present study show that NO concentration is elevated in serum after intestinal I/R and the elevation sustained after administration of L-Arg but not after administration of L-NAME or Allo after 1 hr reperfusion. However, after 8 hrs of reperfusion NO concentration was increased in all groups studied, focusing attention on its possible important role in a complicated situation such as intestinal I/R that involves intestine and other organs. Serum catalase activity does not seem to be affected by per os supplementation of L-Arg or Allo in intestinal I/R.

Effects of the TREM-1 pathway modulation during mesenteric ischemia-reperfusion in rats.

OBJECTIVES: The triggering receptor expressed on myeloid cells (TREM)-1, a receptor expressed on the surface of neutrophils and monocytes/macrophages, synergizes with the Toll-like receptors in amplifying the inflammatory response mediated by microbial components. Because the pathogenesis of ischemia-reperfusion-induced gastrointestinal tissue injury and multiple organ failure implies leukocyte activation and bacterial translocation, we hypothesized that the TREM-1 pathway modulation would prove beneficial in this setting. DESIGN: Animal study. SETTING: Research laboratory. SUBJECTS: Adult male Wistar rats (250-300 g). INTERVENTIONS: Rats were subjected to intestinal ischemia-reperfusion induced by occlusion of the superior mesenteric artery during 60 mins and reperfused for 180 mins. At the time of reperfusion, animals were administered with LP17 (a synthetic TREM-1 inhibitor), a control peptide, or a vehicle (normal saline). Plasma concentrations of tumor necrosis factor-alpha, interleukin-6, and soluble TREM-1 were measured by enzyme-linked immunosorbent assay. Hepatic activation of the transcriptional factor nuclear factor-kappaB was assessed by electrophoretic mobility shift assay. Hepatic oxidant-antioxidant balance was estimated by measurement of lipid peroxidation and catalase activity. Ileal mucosal permeability was estimated by fluorescein dextran-4 clearance and bacterial translocation by mesenteric lymph nodes culture. MEASUREMENTS AND MAIN RESULTS: Ischemia-reperfusion was associated with cardiovascular collapse, lactic acidosis, and systemic and hepatic inflammatory response that were partly prevented by LP17 administration. Liver lipid peroxidation and catalase depletion were attenuated by LP17. Ischemia-reperfusion induced a marked increase in ileal mucosal permeability and an associated bacterial translocation that was also prevented by TREM-1 modulation. LP17 delayed mortality. CONCLUSIONS: The modulation of the TREM-1 pathway by the means of a synthetic peptide may be useful during acute mesenteric ischemia.

Avaliação inicial dos gradientes sistêmicos e regionais da pCO2 como marcadores de hipoperfusão mesentérica / Initial evaluation of systemic and regional pCO2 gradients as markers of mesenteric hypoperfusion

RACIONAL: Apesar dos recentes avanços nos métodos de imagem e no cuidado dos doentes críticos, a taxa de mortalidade do abdome agudo vascular nas últimas duas décadas continua praticamente inalterada. OBJETIVOS: Avaliar as alterações imediatas dos gradientes regionais da pCO2 induzidas pela isquemia e reperfusão mesentérica. Determinar se outros marcadores sistêmicos de hipoperfusão esplâncnica são capazes de detectar precocemente as alterações circulatórias ocorridas na mucosa intestinal após oclusão da artéria mesentérica superior. MÉTODOS: Foram utilizados sete cães machos sem raça definida (20,6 ± 1,1 kg), submetidos a oclusão da artéria mesentérica superior por 45 minutos, sendo os animais observados por período adicional de 2 horas após a reperfusão. Variáveis hemodinâmicas sistêmicas foram avaliadas por meio de cateter arterial e Swan-Ganz. A perfusão do sistema digestório foi avaliada pela medida do fluxo sangüíneo da veia mesentérica superior e da serosa jejunal (fluxômetro ultra-sônico). Oferta, taxa de extração e consumo intestinal de oxigênio (DO2intest, TEO2intest e VO2intest, respectivamente), pH intramucoso (tonometria a gás) e os gradientes veia mesentérica-arterial e mucosa-arterial da pCO2 (Dvm-a pCO2 e Dt-a pCO2, respectivamente), foram calculados. RESULTADOS: A oclusão da artéria mesentérica superior não esteve associada a alterações hemodinâmicas sistêmicas, mas pôde-se observar aumento significativo do Dvm-a pCO2 (1,7 ± 0,5 para 5,7 ± 1,8 mm Hg) e do Dt-a pCO2 (8,2 ± 4,8 para 48,7 ± 4,6 mm Hg). Na fase de reperfusão observou-se redução da DO2intest (67,7 ± 9,9 para 38,8 ± 5,3 mL/min) e conseqüente aumento da TEO2intest de 5,0 ± 1,1 por cento para 12,4 ± 2,7 por cento. Não houve correlação entre os gradientes da pCO2 analisados. CONCLUSAO: A tonometria permite detectar de maneira precoce a redução de fluxo intestinal. Além disso, pudemos demonstrar que as variações dos gradientes regionais e/ou sistêmicos da pCO2 não são capazes de avaliar a magnitude da redução de fluxo da mucosa intestinal durante o fenômeno de isquemia e reperfusão mesentérica.

[Therapeutic effect of zinc sulfate on lung injury during superior mesenteric artery occlusion(SMAO) shock].

AIM: To study preventive and therapeutic effect of zinc sulfate on lung injury during superior mesenteric artery occlusion (SMAO) shock and their mechanism of action. METHODS: Model of rabbit SMAO shock was made. The effect of zinc sulfate on the malondialdehyde (MDA) in erythrocyte membrane and plasma, oxidase (XOD) in plasma, superoxide dismutase (SOD) in erythrocyte and MDA, SOD and pulmonary surfactant (PS) in lung tissues homogenate were observed. RESULTS: The administration of zinc sulfate decreased MDA and XOD, prevented the reduction of SOD and PS, and alleviated lung injury. CONCLUSION: It is suggested that lung is injured during SMAO shock and zinc sulfate possesses preventive and therapeutic effect, through stabilized membrane.

Cardioprotection at a distance: mesenteric artery occlusion protects the myocardium via an opioid sensitive mechanism.

Preconditioning in remote organs protects the myocardium; however, mediators of the protection remain unknown. Protection of the heart is linked to opioids; therefore, we hypothesized that mesenteric preconditioning (MPC) releases endogenous opioids that protect the myocardium from ischemic injury. In an intact rat model of myocardial infarction, all rats underwent 30 min of coronary artery occlusion followed by 2 h of reperfusion. Prior to coronary artery occlusion, control rats were subjected to sham surgery in which the mesenteric artery was isolated but not occluded both with and without naloxone (10mg/kg) pretreatment. Experimental groups underwent isolation and occlusion of the mesenteric artery for 15 min followed by a 10 min reperfusion period with and without naloxone pretreatment. At the end of 2 h of coronary reperfusion, myocardial infarct size (IS) was determined by tetrazolium staining and expressed as a percent of the area at risk (AAR). Control rats had an IS/AAR of 57.3+/-2. MPC resulted in a significant reduction in infarct size compared to controls (32.2+/-3, P<0.001). Pretreatment with naloxone significantly attenuated the protective effects of MPC (53.8+/-4, P<0.0002). Therefore, it appears that MPC releases endogenous opioids that protect the myocardium from ischemic injury.