Reversal of the effect of albumin on gut barrier function in burn by the inhibition of inducible isoform of nitric oxide synthase

HYPOTHESIS: The use of albumin in the early resuscitation formula after major burn has been forbidden because of its damaging effect on the gut barrier function. We hypothesize that inhibition of the inducible isoform of nitric oxide synthase to stabilize endothelial permeability and to retain albumin in the vascular space will ameliorate the major trauma-induced gut barrier dysfunction. DESIGN, INTERVENTIONS, AND MAIN OUTCOME MEASURES: In experiment 1, specific pathogen-free rats undergoing 35% total body surface area burn or sham burn were given equal volumes (7.5 mL/kg) of isotonic sodium chloride solution or albumin from femoral veins for fluid resuscitation at 0, 4, or 8 hours after burn. In experiment 2, intraperitoneal S-methylisothiourea sulfate (7.5 mg/kg) was given immediately after burn to rats from different groups, as in experiment 1 (SMT groups). At 24 hours after burn, the intestinal mucosa was assayed for myeloperoxidase activity as an index for neutrophil sequestration, the distribution of fluorescein isothiocyanate-dextran across the lumen of small intestine was determined to evaluate the intestinal permeability, and bacterial translocation (BT) to the mesenteric lymph nodes (MLNs) and histological findings in the ileum were also examined. RESULTS: Compared with sham burn, burn induced significant increases in intestinal mucosa myeloperoxidase activity, intestinal permeability, BT to the MLNs, and villi sloughing in rats. Albumin administration at 0 or 4 hours after burn enhanced the increases in neutrophil sequestration, permeability, and villi sloughing compared with saline injection at the same times. In contrast, injection of albumin in the burn-SMT group did not aggravate these changes in intestinal myeloperoxidase activity, intestinal permeability, BT to the MLNs, and villi edema. Burn-SMT rats with albumin injections at 4 or 8 hours after burn showed significant 35% and 52% decreases, respectively, in intestinal permeability compared with burn-SMT-saline rats. Use of albumin at 8 hours after burn in combination with S-methylisothiourea significantly attenuated BT to the MLNs and reduced villi edema. CONCLUSIONS: Early albumin resuscitation aggravated the burn-induced gut damage. Albumin administration and inhibition of the inducible isoform of nitric oxide synthase in combination decreased burn-induced gut barrier dysfunction and reversed the damaging effect of albumin on gut barrier function and decreased BT.     

Ligustrazine attenuates acute lung injury after burn trauma

Acute lung injury is a common complication in patients with extensive burns in which the burned area exceeds 30% of the total body surface area (TBSA). This study was undertaken to evaluate the effect of Ligustrazine on burn-induced lung injury as well as the release of interleukin-8 (IL-8) in rats to characterize the role of Ligustrazine and IL-8 in lung injury after burn trauma. Sprague-dawley rats were divided into three groups: (1) sham group, rats who underwent sham burn; (2) control group, rats given third-degree burns over 30% TBSA and lactated Ringer solution for resuscitation; and (3) Ligustrazine group, rats given burn injury and lactated Ringer's solution with Ligustrazine inside for resuscitation. Pulmonary injury was assessed at 24 h by pulmonary capillary permeability determined with fluorescein isothiocyanate-labeled albumin and lung histologic analysis, and lung myeloperoxidase (MPO) activity as well as lung wet/dry weight ratio. The IL-8 levels were measured in serum by enzyme-linked immunosorbent assay. These studies showed that burn trauma results in increased pulmonary leakage permeability and lung wet/dry ratio, elevated serum IL-8 levels and MPO activity, and worsened histologic condition. Ligustrazine inhibited these changes, prevented burn-mediated lung injury, and the production of IL-8. This will likely provide further evidence for ligustrazine as a therapeutic strategy in burn-induced lung injury.     

2-Mercaptoethane sulfonate (MESNA) protects against burn-induced renal injury in rats

Animal models of thermal injury implicate oxygen radicals as causative agents in local wound response and distant organ injury following burn. In this study we investigated the putative protective effects of 2-mercaptoethane sulfonate (MESNA) against oxidative kidney damage in rats with thermal injury. Under ether anaesthesia, shaved dorsum of the rats was exposed to 90 degrees C bath for 10s to induce burn injury. Rats were decapitated either 6 or 24h after burn injury. MESNA was administered i.p. immediately after burn injury. MESNA injections were repeated once more 12h after the first injection in the 24h burn group. In the control group the same protocol was applied except that the dorsum was dipped in a 25 degrees C water bath for 10s. Kidney tissues were taken for the determination of malondialdehyde (MDA) and glutathione (GSH) levels, protein oxidation (PO), myeloperoxidase (MPO) activity and collagen contents. Creatinine, urea concentrations (BUN) and lactate dehydrogenase (LDH) in blood were measured for the evaluation of renal functions and tissue damage, respectively. Tissues were also examined microscopically. Severe skin scald injury (30% of total body surface area) caused significant decrease in GSH level, significant increase in MDA level, protein oxidation (PO), MPO activity and collagen content of renal tissue. Serum creatinine was slightly increased at the early phase of thermal trauma but not changed in 24h groups. On the other hand BUN and LDH were significantly elevated by thermal trauma in both 6 and 24h of burn groups. Treatment of rats with MESNA significantly increased the GSH level and decreased the MDA level, PO, MPO activity, collagen contents, BUN and LDH. Since MESNA reversed the oxidant responses seen in burn injury, it seems likely that MESNA could protect against thermal trauma-induced renal damage.     

高渗氯化钠羟乙基淀粉复合液对失血性休克肺的保护作用

目的观察用高渗氯化钠羟乙基淀粉复合液(7.5%氯化钠 6%羟乙基淀粉200/0.5,HHS)小容量复苏对失血性休克后肺损伤的影响。方法雄性SD大鼠随机分为五组:正常对照组(CON组,n=6):不放血不补液;其他大鼠通过放血使MAP降至45mmHg并维持120min,然后分为:休克组(SH组,n=6),不补液复苏;HHS组(n=8),用HHS5ml/kg静脉滴注;7.5%氯化钠高渗溶液组(HTS组,n=6),用7.5%NaCl5ml/kg静脉滴注;复方乳酸钠组(LR组,n=7),用3倍失血量的复方乳酸钠静脉滴注。观察休克2h末、补液结束即刻、15、30、60、120、180min时MAP、CVP的变化,测定补液结束2、24h存活动物的氧合指数和肺水含量、肺髓过氧化物酶(MPO)水平、肺损伤评分。结果在补液结束120、180min,HTS组MAP、CVP低于HHS和LR组(P<0.05);在补液结束24h,HHS组氧合指数、肺水含量、肺MPO水平、肺损伤评分优于HTS和LR组(P<0.05)。结论用HHS小容量复苏失血性休克,维持血流动力学稳定时间更长;对肺组织的保护作用优于7.5%氯化钠高渗溶液或复方乳酸钠。     

A monoclonal antibody against cytokine-induced neutrophil chemoattractant attenuates injury in the small intestine in a model of ruptured abdominal aortic aneurysm

PURPOSE: Ruptured abdominal aortic aneurysm (RAAA) continues to be a major source of aneurysm-related morbidity and mortality. Neutrophils have been implicated in RAAA repair-induced organ injury; however, the agents responsible for neutrophil activation and organ sequestration have not been identified. This study investigated the role of cytokine-induced neutrophil chemoattractant (CINC) in organ injury in an RAAA model. METHODS: Rats were subjected to 1 hour of hemorrhagic shock with resuscitation, followed by 45 minutes of lower torso ischemia and 2 hours of reperfusion, and randomly were selected to receive saline solution or anti-rat CINC monoclonal antibody at the start of hemorrhagic shock. Another group of animals underwent sham operation, and served as a control group. Intestinal and lung permeability, intestinal and lung myeloperoxidase (MPO) activity, intestinal and lung CINC, and tumor necrosis factor-alpha (TNF-alpha) levels, resuscitation fluid requirements, and histologic mucosal injury were evaluated in all groups. RESULTS: The RAAA model resulted in increased lung and intestinal permeability to radiolabeled albumin and lung MPO activity (P <.01), with increases in intestinal TNF-alpha (P <.001) and CINC (P <.01) levels, when compared with sham-operated animals. Treatment with anti-rat CINC monoclonal antibody attenuated the increases in intestinal permeability and histologic mucosal injury (P <.01), gut TNF-alpha level (P <.001), and resuscitation fluid volume required (P <.05), without significantly affecting lung and intestinal MPO activity, lung permeability, and intestinal CINC level (P = NS), compared with animals given saline solution. CONCLUSION: Neutralization of CINC by the anti-rat CINC monoclonal antibody attenuated intestinal injury and induction of intestinal TNF-alpha, but failed to significantly attenuate remote pulmonary injury in this model of RAAA.     

Specific inhibition of iNOS decreases the intestinal mucosal peroxynitrite level and improves the barrier function after thermal injury

Failure of GI tract mucosa to act as a barrier against bacterial translocation (BT) has been proposed as a potential source of sepsis and subsequent multiple organ failure post thermal injury. Nitric oxide (NO) is an inorganic radical produced by NO synthase (NOS) from -arginine. Gut mucosal constitutive NOS (cNOS) provides protection for itself. In contrast to cNOS, inducible NOS (iNOS) releases far greater amounts of NO, promotes oxidative reactions and is responsible for tissue injury. Peroxynitrite formed by the rapid reaction between superoxide and NO, is a toxic substance that contributes to tissue injury in a number of biological systems. This study was designed to investigate the effect of iNOS specific inhibitor S-methylisothiourea (SMT) on the postburn intestinal mucosal barrier function and the possible mechanism of SMT's action. Female SPF Sprague–Dawley rats underwent 35% total body surface area (TBSA) or sham burn. Either SMT or the same volume of saline was given (5 mg/kg, i.p. q 12 h) for 2 days to assess the effect of iNOS inhibition. On postburn day 2, the intestinal mucosal cNOS and iNOS activity were assayed by using Griess' reagent, the mesenteric lymph node (MLN), spleen and liver were collected and cultured for BT assay and the cellular localization of nitrotyrosine, a marker for peroxynitrite activity, was examined by immunostaining. After thermal injury in rats, administration of SMT for 2 days decreased the intestinal mucosal iNOS activity/tNOS activity ratio and the BT incidence. Nitrotyrosine immunostaining of the intestinal mucosa showed a decrease in the SMT-treated group. These findings suggest that SMT, a specific inhibitor for iNOS improves the barrier function after burn by suppression of the intestinal mucosal iNOS activity. The decrease in NO production resulted in decreased formation of peroxynitrite and subsequently decreased damage of mucosal tissue.     

Postresuscitation tissue neutrophil infiltration is time-dependent and organ-specific

BACKGROUND: Hemorrhagic shock with conventional resuscitation (CR) primes circulating neutrophils and activates vascular endothelium for increased systemic inflammation, superoxide release, and end-organ damage. Adjunctive direct peritoneal resuscitation (DPR) with intraperitoneal instillation of a clinical peritoneal dialysis solution decreases systemic inflammation and edema formation by enhancing tissue perfusion. The aim of this study is to determine the effect of adjunctive DPR on neutrophil and fluid sequestration. METHODS: Anesthetized rats were hemorrhaged to 40% mean arterial pressure for 60 min. Animals were randomized for CR with the return of the shed blood plus two volumes of saline, or CR plus adjunctive DPR with 30 mL of intraperitoneal injection of a clinical peritoneal dialysis solution. Tissue myeloperoxidase (MPO) level, a marker of neutrophil sequestration, and total water content were assessed in the gut, lung, and liver in sham animals and at time-points 1, 2, 4, and 24 h postresuscitation. RESULTS: Resuscitation from hemorrhagic shock increases MPO level in all tissues in a near-linear fashion during the first 4 h following resuscitation. This occurs irrespective of the resuscitation regimen used. Tissue MPO level returned to baseline at 24 h following resuscitation except in the liver where CR and not adjunctive DPR caused a significant rebound increase. Adjunctive DPR prevented the CR-mediated obligatory fluid sequestration in the gut and lung and maintained a relative normal tissue water in these organs compared with CR alone (n = 7, F = 10.1, P < 0.01). CONCLUSION: Hemorrhagic shock and resuscitation produces time-dependent organ-specific trends of neutrophil sequestration as measured with tissue levels of myeloperoxidase, a marker of neutrophil infiltration. Modulation of the splanchnic blood flow by direct peritoneal resuscitation did not alter the time-dependent neutrophil infiltration in end-organs, suggesting a subordinate role of blood rheology in the hemorrhage-induced neutrophil sequestration. Vulnerable window for neutrophil-mediated tissue damage exists during the first 4 h following resuscitation from hemorrhagic shock in rats. Direct peritoneal resuscitation prevents the early obligatory fluid sequestration and promotes early fluid mobilization.     

不同液体腹腔复苏对失血性休克大鼠肠道炎性反应的影响

目的 探讨不同液体腹腔复苏对失血性休克大鼠肠道炎性反应的影响.方法 清洁级健康雄性SD大鼠50只,体重200～250 g,随机分为5组(n=10):假手术组(S组)仅行手术操作,不制备失血性休克模型;采用股动脉置管放血法制备大鼠失血性休克模型,常规静脉复苏组(CVR组)失血性休克1 h后,经左侧股静脉匀速回输自体血及相当于2倍失血量的生理盐水行常规静脉复苏;不同液体腹腔复苏组(DPR1～3组)行常规静脉复苏,同时分别腹腔输注生理盐水、6%羟乙基淀粉130/0.4、2.5%腹膜透析液20 ml行腹腔复苏.输注时间均为30 min.右颈总动脉连接多功能监测仪持续监测平均动脉压;于复苏后2 h时股动脉采血,测定乳酸浓度,取小肠组织检测髓过氧化物酶(MPO)活性,采用免疫组化法检测小肠组织肿瘤坏死因子α(TNF-α)表达水平,光镜下观察小肠黏膜组织形态,计算小肠黏膜上皮损伤指数.结果 与S组比较,其余各组大鼠复苏后平均动脉压差异无统计学意义(P>0.05),动脉血乳酸浓度、小肠组织MPO活性、TNF-α表达水平及小肠黏膜上皮损伤指数升高(P<0.05或0.01);与CVR组比较,DPR3组动脉血乳酸浓度、小肠组织MPO活性、TNF-α表达水平及小肠黏膜上皮损伤指数降低(P<0.05).结论 采用2.5%腹膜透析液20 ml行腹腔复苏可有效抑制肠道炎性反应,从而对失血性休克大鼠产生保护作用.     

Melatonin improves oxidative organ damage in a rat model of thermal injury

Animal models of burn injury indicate oxygen radicals as causative agents in the local wound response, as well as in the development of burn shock and distant organ injury. This study was designed to determine the possible protective effect of melatonin treatment against oxidative damage in the liver, lung and intestine induced by burn injury. Under ether anaesthesia, the shaved dorsum of rats was exposed to a 90 degrees C bath for 10s to induce burn injury. Rats were decapitated either 3 or 24h after burn injury. Melatonin was administered i.p. immediately after burn injury. In the 24h burn group, melatonin injections were repeated for two more occasions. In the sham group the same protocol was applied except that the dorsum was dipped in a 25 degrees C water bath for 10s. Liver, lung and intestine tissues were taken for the determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and protein oxidation (PO). Severe skin scald injury (30% of total body surface area) caused a significant decrease in GSH level, significant increases in MDA and PO levels, and MPO activity at postburn 3 and 24h. Treatment of rats with melatonin (10mg/kg) significantly elevated the reduced GSH levels while it decreased MDA and PO levels as well as MPO activity.     

Systemic perfluorocarbons suppress the acute lung inflammation after gastric acid aspiration in rats

Perflurocarbons (PFCs) are used during liquid ventilation and as hemoglobin substitutes. PFCs reduce free radical generation and damage to the lung during liquid ventilation. Thus, we examined the effects of parenteral administration of PFCs on lung injury after acid aspiration. Rats were treated with intraperitoneal injection of either FC-77 or IV injection of Fluosol. Controls received intraperitoneal or IV normal saline (NS) before or at the time of injury and then were injured by instillation of NS + HCl (pH = 1.25) into their lungs via a tracheotomy. The animals were exposed to air or 98% oxygen, breathing spontaneously. The rats were injected with 0.05 microCi of (125)I-albumin (bovine serum albumin) before injury. The extent of lung injury was assessed 5 h postinjury by compliance and lung albumin permeability index measurement. Myeloperoxidase (MPO) activity and histologic examination were used to assess neutrophilic infiltration. Both FC-77 and Fluosol decreased the permeability index compared with controls (1.05 +/- 0.08; 1.08 +/- 0. 12, respectively, versus 1.34 +/- 0.21) and improved lung compliance after intratracheal instillation of 1.2 mL/kg of HCl/NS, pH = 1.25 + hyperoxia injury (P < 0.05). Lung MPO activity decreased in the FC-77 group and was associated with a concomitant decrease in neutrophil infiltration. MPO activity of the spleen increased after FC-77 treatment. The administration of FC-77 decreased the severity of lung permeability changes associated with acid in the presence or absence of hyperoxia exposure. These data suggest that attenuation of neutrophilic infiltration by PFCs decreases lung injury. IMPLICATIONS: Intraperitoneally administered perfluorocarbons in rats attenuate the neutrophilic infiltration in the lung after acid aspiration, thereby decreasing the alveolar protein leakage and improving pulmonary compliance.     

Insulin protects against damage to pulmonary endothelial tight junctions after thermal injury: Relationship with zonula occludens‐1, F‐actin,and AKT activity

Intensive insulin therapy during critical illness protects the endothelium and thereby prevents organ failure. This study tested the hypothesis that insulin directly affects the attenuation of burn injury‐induced damage to pulmonary endothelial tight junction and investigated the underlying mechanisms. Sprague Dawley rats with severe burn injury were randomized to treatment with insulin dissolved in normal saline (maintenance of blood glucose at a level between 5.0 and 7.0 mmol/L) or normal saline alone (in vivo treatment). Pulmonary damage was evaluated. Rat pulmonary microvascular endothelial cells were treated with 20% burn serum or 20% burn serum + insulin (in vitro treatment). Selected cultures were pretreated with phosphatidylinositol 3‐kinase/protein kinase B (AKT) inhibitor (LY294002). Permeability was assessed by migration of bovine serum albumin across cell monolayers. Cells were stained with rhodamine phalloidin and were examined. Cell extracts were obtained to assess zonula occludens‐1, occludin, and phosphorylated AKT levels by immunoblotting. Treatment with insulin attenuated the pulmonary edema, hemorrhage, and inflammatory cell infiltration of rats with severe burn injury. Burn serum significantly enhanced monolayer permeability to albumin, whereas treatment with insulin (10^?7 mol/L) limited this effect. Meanwhile, insulin (10^?7 mol/L) reduced burn serum‐induced F‐actin stress fiber formation and decreased zonula occludens‐1 expression. LY294002 decreased cytoplasmic AKT phosphorylation and inhibited the protection effects of insulin. Through the phosphatidylinositol 3‐kinase/AKT pathway, insulin independent of glucose toxicity can attenuate increased pulmonary endothelial permeability induced by burn injury. The effect is attributed to the attenuation of the architectural disruption of protein components of the endothelial tight junction. This result is useful in inhibiting multiple organ failure after burn injury.     

Nitric oxide does not cause extravasation in endotoxemic rats

BACKGROUND: Nitric oxide (NO) formed from inducible NO synthase (iNOS) is assumed to promote vascular permeability in sepsis and endotoxemia. METHODS: Thirty-seven anesthetized rats were examined for the effects of endotoxin. After randomization, 17 animals had lipopolysaccharide (LPS) administered and 20 rats served as controls and were given the corresponding volume of saline. The observation period was 5 hours after administration of endotoxin. Mean arterial blood pressure, heart rate, and hematocrit were recorded in all animals, and transcapillary exchange of albumin, tissue water content, immunohistochemistry for nitric oxide synthase, and blood gases were investigated in subsets of animals. RESULTS: When anesthetized rats were studied for 5 hours after endotoxin (LPS), the sequestration of albumin decreased in the intestine (double-isotope method) and there was no increased water content (freeze-drying technique) when the elevated tissue plasma volume of the LPS-treated rats was corrected for. Immunohistochemical methods showed a similar distribution and intensity of staining for endothelial NOS and neuronal NOS in LPS and control groups. In the lung of the LPS-treated rats, there was a significantly larger number of infiltrating, inflammatory cells staining for iNOS. There was no iNOS demonstrated in vascular structures or heart. CONCLUSION: At 5 hours after LPS, there was no increased loss of water or albumin from the circulation. This challenges the notion that NO causes vascular damage in endotoxemia and extravasation as an obligatory sequela to endotoxemia.     

Scavenging of Peroxynitrite Reduces Renal Ischemia/Reperfusion Injury

Introduction. Nitric oxide (NO) and peroxynitrite (OONO—) are implicated in the pathophysiology of renal ischemia/reperfusion (I/R). The aim of this study was to investigate and compare the efficiency of S-methylisothiourea (SMT), an iNOS inhibitor, and mercaptoethylguanidine (MEG), a scavenger of peroxynitrite, on renal dysfunction and injury induced by I/R of rat kidney. Materials and Methods. Thirty-two male Sprague-Dawley rats were divided into four groups: sham-operated, I/R, I/R+SMT, and I/R+MEG. Rats were given SMT (10 mg/kg ip) or MEG (10 mg/kg ip) 6 h prior to I/R and at the beginning of reperfusion. All rats except sham-operated underwent 60 min of bilateral renal ischemia followed by 6 h of reperfusion. After reperfusion, kidneys and blood were obtained for evaluation. Superoxide dismutase, glutathione peroxidase, malondialdehide, protein carbonyl content, and nitrite/nitrate level (NO_x) were determined in the renal tissue. Serum creatinine (S_Cr), blood urea nitrogen (BUN), and aspartate aminotransferase (AST) were determined in the blood. Additionally, renal sections were used for histological grade of renal injury. Results. SMT and MEG significantly reduced the I/R-induced increases in S_Cr, BUN, and AST. Both SMT and MEG attenuated the tissue NO_x levels, indicating reduced NO production. In addition, SMT and MEG markedly reduced elevated oxidative stress product, restored decreased antioxidant enzymes, and attenuated histological alterations. Interestingly, MEG exerted a greater renoprotective effect than SMT. Conclusions. These data support the finding that iNOS and peroxynitrite are involved in the renal I/R injury, and suggest that a scavenger of peroxynitrite might be more effective than iNOS inhibitors as a therapeutic intervention.     

Pulmonary edema in an isolated lobe after inhalation injury

In order to know the regularity of forming edema after thermal injury, we performed experiments of pulmonary edema in isolated lobes with steam and obtained direct continuous measurements of transudation as it occurs. Transvascular flux (Qf) and gain weight (Gw) of the lobe increased immediately and the peak value of exudation occurred within half an hour after inhalation injury. Studies in protein content, colloid osmotic pressure of bronchus exudate and water content of lung, reconfirmed increase in pulmonary capillary permeability. Marked hemoconcentration was revealed. Plasma leaked 145 ml (32.5%), plasma protein leaked 2.9 g (15%) during the experiment. According to pressure of artery (Pa), vein (Pv), arterial occlusion (Pao), venous occlusion (Pvo), double occlusion (Pdo) and blood flow through the lobe (QT), the total vascular (Rt) arterial (Ra), middle compartment (Rmid), and venous (Rv) resistances were calculated. All the resistances indicated an increase and QT showed a decrease after inhalation injury. The experimental results suggested that tissue ischemia is significant after thermal injury and resuscitation should be started as early as possible and should include whole blood or plasma in resuscitation regimes during burn shock phase.     

Controversies in the fluid management of post-traumatic lung disease

The appropriate intravenous therapy for injured patients is controversial. Use of colloid-containing solutions has been advocated in an attempt to maintain intravascular colloid osmotic pressure, minimize pulmonary oedema and draw fluid out of areas of contused lung. Studies of animals with lymph fistulas in the lung do not support such therapy and there is no difference between lung water volumes in animals resuscitated for 3 hours with colloid as opposed to crystalloid solutions after a standardized traumatic insult (colloid = 8.4 + 0.8 ml/kg; crystalloid = 7.5 + 0.6 ml/kg). Increased pulmonary capillary permeability makes such therapeutic attempts to 'dry out' the lungs even less effective. Studies in human patients of the rate of extravasation of labelled albumin from the pulmonary intravascular space indicate that increased permeability of pulmonary capillaries occurs early after injury and remains elevated in many severely injured patients. Low plasma colloid osmotic pressures do not correlate with increases in extravascular lung water. A shift to the use of vigorous crystalloid resuscitation of injured patients at our institution has resulted in decreases in both mortality rate (1976-1979, 35 per cent; 1979-1981, 28 per cent) and the rate of dialysis-dependent renal failure (1976-1979, 6 per cent; 1979-1981, 2 per cent). Current evidence supports the use of crystalloid solutions together with blood for resuscitation after injury.     

Leukotriene receptor blocker montelukast protects against burn-induced oxidative injury of the skin and remote organs

Thermal injury elicits several systemic consequences, among them the systemic inflammatory response where the generation of reactive oxygen radicals and lipid peroxidation play important roles. In the present study, we investigated whether the leukotriene receptor blocker montelukast is protective against burn-induced remote organ injury. Under brief ether anaesthesia, shaved dorsum of the rats was exposed to 90 degrees C (burn group) or 25 degrees C (control group) water bath for 10 s. Montelukast (10 mg/kg) or saline was administered intraperitoneally immediately after and at the 12th hour of the burn injury. Rats were decapitated 24 h after burn injury and the tissue samples from lung, liver, kidney and skin were taken for the determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen contents. Tissues were also examined microscopically. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels and creatinine, urea (BUN) concentrations were determined to assess liver and kidney function, respectively. Tumor necrosis factor-alpha (TNF-alpha) and lactate dehydrogenase (LDH) were also assayed in serum samples. Severe skin scald injury (30% of total body surface area) caused a significant decrease in GSH level, which was accompanied with significant increases in MDA level, MPO activity and collagen content of tissues. Similarly, serum ALT, AST and BUN levels, as well as LDH and TNF-alpha, were elevated in the burn group as compared to control group. On the other hand, montelukast treatment reversed all these biochemical indices, as well as histopathological alterations, which were induced by thermal trauma. Findings of the present study suggest that montelukast possesses an anti-inflammatory effect on burn-induced damage in remote organs and protects against oxidative organ damage by a neutrophil-dependent mechanism.     

Effect of early wound excision on changes in plasma nitric oxide and endothelin-1 level after burn injury: an experimental study in rats

The purpose of this study was to evaluate effects of early wound excision on changes in NO and endothelin-1 (ET-1) level in the plasma after extensive burn injury. The effects on vascular permeability and hepatic blood flow (HBF) were also assessed. Male Wistar rats were used for this study. A 30% total body surface area (TBSA) third-degree burn was made on the back. Then animals were divided into four groups. Burn group (n = 13), burn alone; infusion group (n = 13), burn injury and fluid resuscitation; early excision group (n = 13), burn injury, total wound excision at 30 min after the injury followed with immediate allogenic skin graft and fluid resuscitation; and the sham group (n = 15). The sham group and the early excision group did not show significant changes in the NO and ET-1 level in plasma during experimental period, while the burn group and the infusion group showed significant increase in the NO and ET-1. The early excision group also did not show hypovolemia, and the significant decrease in the HBF. These data suggest that the increased NO and ET-1 in plasma following thermal injury were originated from burned tissue and the removal of these injured tissue has beneficial effect on the vascular permeability and the changes in HBF.     

The effect of N-acetylcysteine on oxidative stress in intestine and bacterial translocation after thermal injury

Ischemia due to transient splanchnic vasoconstriction following major burns causes oxidative and/or nitrosative damage in intestinal tissue followed by reperfusion injury. Thus, burn injury leads to breakdown in the intestinal mucosal barrier which can induce bacterial translocation (BT). As an antioxidant and anti-inflammatory agent the protective effects of N-acetylcysteine (NAC) are documented in several studies. This study was designed to determine the effect of NAC treatment on the oxidative stress in the intestine and BT after burn injury. To evaluate this, 32 Wistar rats were randomly divided into four groups as sham (n = 8), burn (n = 8), pre-burn, NAC injection (150 mg kg⁻¹, intraperitoneally) 15 min before thermal injury (n = 8), post-burn, NAC injection (150 mg kg⁻¹, intraperitoneally) 2 h after thermal injury. Under anesthesia, the shaved dorsal skin of rats was exposed to boiling water for 12 s to induce burn injury in a standardized manner. Twenty-four hours later, tissue samples from mesenteric lymph nodes (MLN), spleen, and liver were obtained under sterile conditions for microbiological analysis and ileum samples were harvested for biochemical analysis. In the burn group, the incidence of isolating bacteria in MLN, spleen, and liver specimens was significantly higher than other groups. NAC treatment prevented burn-induced BT in both pre- and post-burn groups. Thermal injury caused a significant decrease in glutathione (GSH) level, significant increases in malondialdehyde (MDA) and myeloperoxidase (MPO) activity at post-burn 24th hour. Treatment of rats with NAC significantly elevated the reduced GSH levels while decreasing MDA levels and MPO activity. These data suggested that NAC has a crucial cytoprotective role in intestinal mucosal barrier and preventive effects against burn injury-induced BT.     

Rosiglitazone, a PPAR-gamma ligand, protects against burn-induced oxidative injury of remote organs

Severe burn induces the activation of an inflammatory cascade that contributes to the development of subsequent immunosuppression, increased susceptibility to sepsis, as well as generation of reactive oxygen radicals and lipid peroxidation, leading to multiple organ failure. In the present study, we investigated whether rosiglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligand is protective against burn-induced remote organ injury. Under brief ether anaesthesia, shaved dorsum of the rats were exposed to 90 degrees C (burn group) or 25 degrees C (control group) water bath for 10s. Rosiglitazone (4 mg/kg) or saline was administered intraperitoneally immediately after and at the 12th hour of the burn. Rats were decapitated 24h after injury and the tissue samples from lung, liver, and kidney were taken for the determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen contents. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels, and creatinine, blood urea concentrations (BUN) were determined to assess liver and kidney function, respectively. Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and lactate dehydrogenase (LDH) were also assayed. Severe skin scald injury (30% of total body surface area) caused a significant decrease in GSH level, and significant increases in MDA level, MPO activity and collagen content of tissues. Similarly, serum ALT, AST and BUN levels, as well as LDH, IL-1 beta and TNF-alpha were elevated in the burn group as compared to the control group. Rosiglitazone treatment reversed all these biochemical indices. According to the findings of the present study, rosiglitazone possesses a anti-inflammatory effect that prevents burn-induced damage in remote organs and protects against organ damage.     

冬眠合剂对严重烫伤大鼠肺损伤的保护作用

目的 观察早期应用冬眠合剂对严重烫伤大鼠肺损伤是否具有保护作用. 方法建立Ⅲ度烫伤大鼠模型,随机分为冬眠合剂组和对照组(未用冬眠合剂),每组36只.分别在伤后3、5、7、10 d测定大鼠动脉血氧分压,检测肺组织中过氧化物酶(MPO)活性、丙二醛(MDA)含量、肿瘤坏死因子α(TNF-α)及γ干扰素(IFN-γ)蛋白表达,动态观察伤后肺组织病理学变化. 结果与对照组大鼠伤后3 d动脉血氧分压(8.86±0.23)kPa(1 kPa=7.5 mm Hg)比较,冬眠合剂组该时相点明显升高[(12.58±0.41)kPa,P<0.01].冬眠合剂组大鼠伤后各时相点肺组织MPO活性和MDA含量下降(P<0.05或P<0.01);伤后3、5、7 d肺组织TNF-α表达显著下调(P<0.05或P<0.01),伤后5、7、10 d肺组织IFN-γ的表达亦显著下调(P<0.01).冬眠合剂组大鼠肺泡间质水肿减轻,炎性细胞浸润减少. 结论大鼠烫伤后及时复苏并给予冬眠合剂,能适度抑制机体应激反应并下调促炎因子表达,改善早期肺功能.