Increased intestinal permeability associated with infection in burn patients

Thermal injury may be associated with disruption of normal gut barrier integrity. To test this hypothesis, we assessed intestinal permeability with the nonmetabolizable, poorly absorbed disaccharide lactulose, which is efficiently excluded by the normal intestinal mucosa. Permeability studies were performed in 15 burned patients (aged 18 to 67 years; mean burn size, 40%) and 11 healthy controls. Lactulose, 10 g, was administered enterally, together with 5 g of mannitol as a control, and urinary excretion rates were determined. Lactulose excretion and the lactulose/mannitol excretion ratio increased threefold (160 +/- 30 vs 57 +/- 7 mumol and 0.113 +/- 0.033 vs 0.035 +/- 0.005) in the infected patients (sepsis score, 10 +/- 2; burn size, 38% +/- 6%). In contrast, noninfected burn patients (sepsis score, 0) had permeability values similar to those of controls (66 +/- 10 mumol and 0.036 +/- 0.007). Permeability increased as the severity of infection increased. Infection in burn patients is associated with increased bowel permeability. The intestine may be a primary source of sepsis. Alternatively, the systemic response to infection may alter gut barrier function, which could facilitate translocation of bacteria and absorption of endotoxin.     

Intestinal and systemic endotoxaemia after laparotomic or laparoscopic cholecystectomy

Since laparoscopic cholecystectomy (LC) is widely recognised as being a "mild" or minimally invasive kind surgery, the aim of this prospective non-randomised study was to investigate the effect of intestinal manipulation on intestinal permeability and endotoxaemia in patients undergoing elective cholecystectomy, comparing the laparoscopic and laparotomic approaches. The intestine is susceptible to operations at remote locations, and the barrier function is altered during intestinal manipulation, leading to bacterial or endotoxin translocation into the systemic circulation. Fifty-three patients undergoing elective cholecystectomy were divided into two groups on the basis of laparotomic (n = 27) or laparoscopic (n = 26) approach. Intestinal permeability was measured preoperatively, and on day 1 and day 3 after surgery using the lactulose/mannitol absorption test. Serial venous samples were taken at 0, 30, 60, 90, 120 and 180 minutes, and at 12, 24 and 48 hours after surgery, for endotoxin measurement using the chromogenic limulus amoebocyte lysate assay. Intestinal permeability was significantly increased on day 1 [0.106 +/- 0.0005 (mean +/- S.E.M.)] in the laparotomic group compared to the preoperative level (0.019 +/- 0.005, p < 0.05) and to the laparoscopic group on day 1 (0.019 +/- 0.005, p < 0.05) which showed no change in comparison with the preoperative level. A significantly higher concentration of systemic endotoxin was detected intraoperatively in the laparotomic group of patients in comparison with the laparoscopic group (p < 0.05). There was significant positive correlation between systemic endotoxaemia and intestinal permeability (rs = 0.958; p = 0.001). An increase in intestinal permeability and degree of systemic endotoxaemia are observed during laparotomic cholecystectomy. This suggets that intestinal manipulation may impair the mucosal barrier function of the gut and contribute to the systemic inflammatory response seen in open cholecystectomy.     

Intestinal permeability and systemic endotoxemia after laparotomic or laparoscopic cholecystectomy

OBJECTIVE: Because laparoscopic cholecystectomy (LC) is widely recognized as a "mild" or "mini-invasive" kind of surgery, in this prospective nonrandomized study, we investigated the effect of intestinal manipulation on intestinal permeability and endotoxemia, in patients undergoing elective cholecystectomy by comparing the laparoscopic with the laparotomic approach. SUMMARY BACKGROUND DATA: The intestine is susceptible to operations at remote locations, and the barrier function is altered during intestinal manipulation, leading to bacterial or endotoxin translocation into the systemic circulation. METHODS: Forty-three patients undergoing elective cholecystectomy were divided into either the laparotomic (n = 22) or laparoscopic (n = 21) approach. Intestinal permeability was measured preoperatively and at day 1 and day 3 after surgery using the lactulose/mannitol absorption test. Serial venous blood samples were taken at 0, 30, 60, 90, 120, and 180 minutes, and at 12, 24, and 48 hours after surgery, for endotoxin measurement using the chromogenic limulus amoebocyte lysate assay. RESULTS: Intestinal permeability was significantly increased at day 1 [0.106 +/- 0.005 (mean +/- SEM)] in the laparotomic group compared with the preoperative level (0.019 +/- 0.005, P < 0.05) and to the laparoscopic group at day 1 (0.019 +/- 0.005, P < 0.05), which showed no change in comparison with the preoperative level. A significantly higher concentration of systemic endotoxin was detected intraoperatively in the laparotomic group of patients in comparison to the laparoscopic group (P < 0.05). There was a significant positive correlation between systemic endotoxemia and intestinal permeability (r(s) = 0.958; P = 0.001). CONCLUSIONS: An increase in intestinal permeability and a greater degree of systemic endotoxemia are observed during laparotomic cholecystectomy. This suggests that intestinal manipulation may impair gut mucosal barrier function and contribute to the systemic inflammatory response see in open cholecystectomy.     

Intestinal permeability is increased in burn patients shortly after injury

There is increasing direct experimental and indirect clinical evidence to indicate that under certain conditions intestinal barrier function may be lost in trauma victims. No direct measurements, however, have been performed in patients to determine whether intestinal permeability is increased shortly after a major thermal injury in the absence of infection. Fifteen hemodynamically stable burn patients with burns on more than 20% of their body surface (39% +/- 12%) had their intestinal permeability measured within 24 hours of injury with use of the two nonmetabolizable sugars lactulose and mannitol as permeability markers. Lactulose absorption was fourfold higher in the patients (223 +/- 54 mumol) than in the controls (58 +/- 11 mumole; p less than 0.02), whereas the lactulose/mannitol ratio was threefold higher (5.2 vs 1.7; p less than 0.05). Thus intestinal permeability was increased in patients with moderate to major burn injuries shortly after injury.     

肝细胞生长因子对移植小肠通透性及细菌易位的作用

目的探讨肝细胞生长因子（hepatocyte growth factor,HGF）对移植小肠通透性及细菌易位的作用。方法以Wistar大鼠20只为受体,SD大鼠20只为供体行异位全小肠移植,并以环孢素A（6mg/kg.d）肌注抑制排斥反应。HGF组（n=10）用微量输液泵持续均匀输入HGF（150μg/kg.d）,对照组（n=10）输入等量生理盐水,随机选取同批正常Wistar大鼠作为正常基准（n=10）。第7天两组实验动物均分别以乳果糖/甘露醇液2ml（含乳果糖100mg、甘露醇50mg）行移植小肠灌注,采集24h尿液检测乳果糖、甘露醇含量及乳果糖/甘露醇比值;第8天采集移植小肠肠系膜淋巴结及门静脉血行细菌培养,小肠组织学观察。结果对照组尿液中乳果糖含量为0.0931%±0.0085%,乳果糖/甘露醇比值为0.132±0.021,与正常基准0.0150%±0.0020%和0.020±0.005比较,差异均有统计学意义（P〈0.05）;HGF组乳果糖含量为0.0396%±0.0090%,乳果糖/甘露醇比值为0.056±0.013,与正常基准比较差异均有统计学意义（P〈0.05）,且低于对照组（P〈0.05）。HGF组移植小肠肠系膜淋巴结细菌阳性率为10%,对照组为60%,差异有统计学意义（P〈0.05）。HGF组门静脉血细菌阳性率为10%,对照组为20%,差异无统计学意义（P〉0.05）。两组移植小肠组织学观察仅见少量炎性细胞浸润。结论HGF能够降低同种移植小肠的通透性及细菌易位率,改善小肠黏膜屏障功能。     

Host immune responses and intestinal permeability in patients with jaundice

BACKGROUND: Systemic endotoxaemia is implicated in the development of complications associated with obstructive jaundice. The aims of these studies were to assess the systemic immune response to intervention in patients with jaundice and to compare the effects of surgical and non-surgical biliary drainage on host immune function and gut barrier function. METHODS: In the first study, 18 jaundiced and 12 control patients were studied to assess systemic immune responses before and after intervention. In the second study, immune responses and gut barrier function were assessed following surgical and non-operative biliary decompression in 45 patients with jaundice. RESULTS: Endotoxin antibody concentrations fell significantly in patients with jaundice immediately after surgical intervention, but not after non-operative biliary drainage. This decrease was associated with a significant increase in serum P(55) soluble tumour necrosis factor (sTNF) receptor concentration (5.3 versus 10.5 ng/ml; P < 0.001), urinary excretion of P(55) TNF receptors (21.4 versus 78.8 ng/ml; P = 0.002) and intestinal permeability (lactulose : mannitol ratio 0.032 versus 0.082; P = 0.048). Intestinal permeability was significantly increased in patients with jaundice compared with controls (0.033 versus 0.015; P = 0.002). CONCLUSION: These data suggest that obstructive jaundice is associated with impaired gut barrier function and activation of host immune function that is exacerbated by intervention. Surgery causes an exaggerated pathophysiological disturbance not seen with non-operative biliary drainage procedures.     

Changes in Intestinal Permeability after Roux-en-Y Gastric Bypass

Background

Roux-en-Y gastric bypass (RYGB) interferes considerably with the anatomy and physiology of the gastrointestinal tract. The study of intestinal permeability can provide important information regarding changes in the structure and function of the mucosal barrier after the procedure.

Methods

The urinary excretion rates of lactulose and mannitol after oral intake of both substances were evaluated. We also evaluated the lactulose/mannitol excretion ratio. Tests were performed during the preoperative period (T0), at the first postoperative month (T1), and at the sixth postoperative month (T6).

Results

The study included 16 morbidly obese patients. The excretion rate of mannitol was significantly lower at T1 compared with T0 and T6 (p?=?0.003). There was no significant difference in the excretion rates of lactulose or in the lactulose/mannitol ratio during the three periods. Six patients (37.5 %) exhibited a considerable increase in the excretion rate of lactulose at T6 (4–73 times higher than the preoperative value), accompanied by proportional variations in the lactulose/mannitol ratio.

Conclusions

The significant increase in mannitol excretion rate from T1 to T6 most likely reflects the occurrence of intestinal adaptation (mucosal hyperplasia), which would tend to minimize the malabsorption of macronutrients. A subgroup of patients who undergo RYGB exhibit pronounced increase in their intestinal permeability (assessed by the lactulose/mannitol ratio and the lactulose excretion rate) at T6.     

Intestinal Manipulation During Elective Aortic Aneurysm Surgery Leads to Portal Endotoxaemia and Mucosal Barrier Dysfunction

OBJECTIVES: to investigate the effect of intestinal manipulation on intestinal permeability and endotoxaemia during elective abdominal aortic aneurysm (AAA) surgery. DESIGN: prospective randomised controlled study. PATIENTS AND METHODS: fourteen patients undergoing elective infrarenal AAA repair were randomised into either the transperitoneal (n=7) or extraperitoneal approach (n=7). Intestinal permeability was measured preoperatively (PO), and at day 1 (D1) and day 3 (D3) after surgery using the lactulose/mannitol absorption test. Portal and systemic blood samples were taken before clamping, at completion of proximal and distal anastomoses and immediately before abdominal wound closure, for endotoxin measurement using the chromogenic limulus amoebocyte lysate assay. RESULTS: intestinal permeability was significantly increased at D1 (0.107+/-0.04 (mean+/-S.E.M.)) in the transperitoneal group compared to the PO level (0.020+/-0.004, p<0.05) and to the extraperitoneal group at D1 (0.020+/-0.004, p<0.05) which showed no change in comparison with the PO level. No correlation was seen between increased intestinal permeability and aortic clamp time, operation time, amount of blood lost or transfused. However, a significantly higher concentration of portal endotoxin was detected intraoperatively in the transperitoneal group of patients in comparison to the extraperitoneal group (p<0.05). There was a significant positive correlation between portal endotoxaemia and intestinal permeability (r(s)=0.955 p=0.001). CONCLUSION: an increase in intestinal permeability and a greater degree of portal endotoxaemia are observed during transperitoneal approach to the aorta. This suggests that intestinal manipulation may impair gut mucosal barrier function and contribute to the systemic inflammatory response seen in AAA surgery.     

Cytokine regulation of intestinal glutamine utilization.

The effects of cytokines on intestinal glutamine metabolism were studied to gain further insight into the regulation of altered glutamine metabolism that occurs during severe infection. One hundred thirteen adult rats were given a single dose of interleukin-1 (IL-1, 50 micrograms/kg), tumor necrosis factor (TNF, 50 micrograms/kg or 150 micrograms/kg), or saline (controls), and flux studies were performed 4 or 12 hours later. Intestinal blood flow was not different between control and cytokine-treated animals at either time point. At the 4-hour time point, arterial glutamine fell by 16% to 21% in the cytokine-treated animals (p less than 0.05); at the 12-hour time point, the arterial glutamine concentration had returned to normal. Intestinal glutamine extraction decreased in the animals treated with IL-1 at both time points (4 hours: 13% +/- 1.3% in IL-1 versus 20% +/- 1.6% in controls, p less than 0.05; and 12 hours: 9% +/- 2% in IL-1 versus 17% +/- 2% in controls, p less than 0.05). Consequently, net intestinal glutamine uptake fell in the animals treated with IL-1 at both time points (p less than 0.05). Similarly, the activity of mucosal glutaminase, the principal enzyme of glutamine hydrolysis in the gut, fell by 50% in the 4-hour study (6.1 +/- 0.6 mumol/h/mg protein in IL-1 versus 9.6 +/- 0.8 mumol/h/mg protein in controls, p less than 0.01) and by 40% in the 12-hour study (5.4 +/- 0.5 mumol/h/mg protein in IL-1 versus 8.8 +/- 0.4 mumol/h/mg protein in controls, p less than 0.05). Concomitant with the aforementioned decrease in gut glutamine metabolism was a 25% incidence of positive blood cultures for gram-negative organisms in IL-1 treated rats studied at the 12-hour time point (p = 0.05 versus controls). In the doses administered and at the time points studied, TNF had no effects on the parameters of gut glutamine metabolism examined. The results indicate that IL-1 is a potential mediator of the alterations in gut glutamine metabolism observed in sepsis and endotoxemia.     

Glutamine improves intestinal barrier function in experimental biliary obstruction

OBJECTIVE: To determine the effects of enteral administration of glutamine on intestinal barrier function in experimental biliary obstruction. BACKGROUND: Extrahepatic biliary obstruction is associated with the failure of intestinal barrier function, allowing bacteria and other substances from the intestine to enter the circulation and initiate a systemic inflammatory response, causing impairment of multiple organs. The amino acid glutamine has been shown to improve intestinal barrier function in other conditions, but its effects in biliary obstruction have not been fully examined. METHODS: This study examined the effects of enteral administration of glutamine on intestinal permeability and on bacterial translocation from the intestine in a rodent model of biliary obstruction. RESULTS: Glutamine was shown to reduce intestinal permeability measured as percentage excretion of 14C 7 days after biliary obstruction (0.35+/-0.03 vs. 0.56+/-0.085% in controls, p=0.028), and glutamine administration was also associated with a decreased incidence of bacterial translocation to extra-intestinal sites (p=0.03). Radiolabelled bacterial studies also demonstrated reduced translocation of bacterial fragments to extra-intestinal sites in glutamine-treated animals (p=0.01). There was also some evidence of decreased exposure to endotoxin, reduced systemic inflammation and increased bacterial killing by the immune system in glutamine-treated animals. CONCLUSIONS: Glutamine modulates intestinal permeability and reduces bacterial translocation in an animal model of experimental biliary obstruction and may increase bacterial killing by the immune system.     

Alterations in intestinal permeability after thermal injury.

Alterations in intestinal permeability have been postulated to occur after thermal injury. We evaluated the status of intestinal permeability during the first 2 postburn weeks in 15 subjects by measuring the differential excretion of enterally administered lactulose and mannitol. The mean age and burn size of the patients were 32.7 +/- 3.6 years and 53.3% +/- 5.1% of the total body surface area, respectively. Ten healthy volunteers were also studied. The lactulose-mannitol excretion ratio was 0.159 +/- 0.017 for the patients and 0.017 +/- 0.003 for controls. The increased ratio did not correlate with burn size or postburn day. Patients who developed significant clinical infections during their first 2 postburn weeks had lactulose-mannitol ratios on postburn day 2 that were significantly higher than those of controls and patients who did not develop infections. This suggests a relationship between susceptibility to infection and early alterations in intestinal permeability.     

Angiotensin II inhibitor DuP753 attenuates burn- and endotoxin-induced gut ischemia, lipid peroxidation, mucosal permeability, and bacterial translocation

OBJECTIVE: To investigate the role of angiotensin II as a mediator of burn- and sepsis-induced gut ischemia and reperfusion injury and to determine whether treatment with the angiotensin II inhibitor DuP753 can attenuate mucosal injury and bacterial translocation in a burn/endotoxemia porcine model. SUMMARY BACKGROUND DATA: Thermal injuries and endotoxemia have been shown to induce ischemia and reperfusion injury to the intestine, leading to increased mucosal permeability and bacterial translocation. Angiotensin II, the production of which has been reported to increase after burn, is thought to be one of the primary mediators of postburn mesenteric vasoconstriction. METHODS: An ultrasonic flow probe was inserted into the superior mesenteric artery and a catheter into the superior mesenteric vein in 21 female pigs. After 5 days, all animals were anesthetized, and 14 received 40% total body surface area third-degree burn. DuP753 was administered intravenously at 1 microg/kg to seven pigs immediately after burn. Eighteen hours after burn, 100 microg/kg Escherichia coli lipopolysaccharide (LPS) was intravenously administered. Systemic and splanchnic hemodynamics were measured and blood samples were drawn for blood gas analysis. Plasma conjugated dienes (PCDs), an index of lipid peroxidation, were measured every 6 hours. Intestinal permeability was assessed every 6 hours by measuring the lactulose/mannitol excretion ratio. At the end of the study (42 hours), tissue samples were harvested for bacteriologic cultures. RESULTS: Burn caused a significant decrease in mesenteric blood flow, to approximately 58% of baseline. Postburn endotoxemia significantly reduced the blood flow in the superior mesenteric artery to 53% of baseline. Treatment with DuP753 prevented postburn vasoconstriction and subsequently abrogated the impact of postburn endotoxemia on blood flow in the superior mesenteric artery. Mesenteric oxygen supply was significantly reduced after burn and endotoxin to 60% and 51% of baseline levels, respectively. DuP753 administration significantly improved mesenteric oxygen supply after both insults. Burn- and LPS-induced mesenteric hypoxia, as indicated by decreased mesenteric oxygen consumption, was also ameliorated by DuP753 treatment. PCD levels were significantly elevated 8 hours after burn. LPS caused a higher and prolonged increase in PCD levels. Treatment with DuP753 significantly reduced PCD levels after burn and after LPS. Intestinal permeability, as assessed by the lactulose/mannitol ratio, showed 6-fold and 12-fold increases after thermal injury and LPS, respectively. In contrast, the lactulose/mannitol ratio was only doubled in DuP753-treated animals. Bacterial translocation was significantly increased after burn and endotoxin. The incidence of bacterial translocation in the DuP753-treated animals was similar to that in the sham group. CONCLUSIONS: Angiotensin II appears to play a pivotal role in the burn- and endotoxin-induced intestinal ischemia and reperfusion injury, with subsequent increases in permeability and bacterial translocation. Postburn administration of the angiotensin II receptor antagonist DuP753 significantly reduces the extent of these events.     

Relationship between disruption of the unstirred mucus layer and intestinal restitution in loss of gut barrier function after trauma hemorrhagic shock

BACKGROUND: The factors involved in shock-induced loss of gut barrier function remain to be defined fully and studies investigating gut injury have focused primarily on the systemic side of the intestine. METHODS: Male Sprague-Dawley rats were subjected to a laparotomy (trauma) and 90 minutes of trauma sham shock (T/SS) or actual trauma (laparotomy) hemorrhagic shock (T/HS) (30 mm Hg). At 0, 30, 60, or 180 minutes after the end of shock and volume resuscitation (reperfusion), the animals were killed and samples of the ileum were collected for intestinal morphologic analysis, analysis of the unstirred mucus layer, and for barrier function by measuring permeability to flourescein dextran. RESULTS: T/HS-induced morphologic evidence of mucosal injury as well as epithelial apoptosis was present at the end of the shock period and maximal after 60 minutes of reperfusion. At 3 hours after reperfusion, the degree of villous injury and enterocyte apoptosis had decreased. In contrast to the morphologic appearance of the villi, disruption of the mucus layer became progressively more severe over time and was manifest as a decrease in mucus thickness, progressive loss of coverage of the luminal surface by the mucus layer, and a change in mucus appearance from a dense to a loose structure. Studies of intestinal permeability documented that T/HS-induced loss of gut barrier function persisted throughout the 3-hour reperfusion period and were associated with injury to the mucus layer as well as the villi. CONCLUSIONS: T/HS leads to changes in the intestinal mucus layer as well as increased villous injury, apoptosis, and gut permeability. Additionally, increased gut permeability was associated with loss of the intestinal mucus layer suggesting that T/HS-induced injury to the mucus layer may contribute to the loss of gut barrier function.     

谷氨酰胺在重型颅脑损伤患者营养支持中的应用

目的研究谷氨酰胺强化营养治疗对重型颅脑损伤患者救治和营养支持巾的作用。方法对52例重型颅脑损伤患者分组进行谷氨酰胺强化营养治疗和常规营养治疗,测定其乳果糖排泄率和血浆内毒素水平并进行统计学处理,分析谷氨酰胺对脑外伤后肠黏膜屏障功能的影响,和在营养支持治疗中的作用。结果脑损伤患者早期内毒素水平明显升高,而在运用谷氨酰胺结合的肠内营养支持治疗下,其血浆内毒素水平要低于对照组,乳果糖排泄率明显较低。结论谷氨酰胺强化的营养支持能够保护肠粘膜屏障,并在颅脑损伤的救治中发挥作用。     

Resuscitation-induced gut edema and intestinal dysfunction

BACKGROUND: Mesenteric venous hypertension and subsequent gut edema play a pivotal role in the development of intra-abdominal hypertension. Although gut edema is one cause of intra-abdominal hypertension, its impact on gut function is unknown. The purpose of this study was to create a model of acute hydrostatic gut edema and to evaluate its effect on gut motility and barrier function. METHODS: The first study, group A, evaluated the effect of gut edema on transit over time using 20 mL/kg 0.9% saline. The second study, group B, focused on the 12-hour time period using 80 mL/kg 0.9% saline. Rats were randomized to superior mesenteric vein partial occlusion (venous hypertension) or sham surgery. At 6, 12, and 24 hours, group A underwent intestinal transit and tissue water weight measurements. At 12 hours, group B underwent tissue water, transit, ileal permeability and resistance, lactate and myeloperoxidase activity, and mucosal injury measurements. RESULTS: Venous hypertension with fluid resuscitation caused acute hydrostatic gut edema, delayed intestinal transit, increased mucosal permeability to macromolecules, and decreased tissue resistance over time. Mucosal injury was minimal in mesenteric venous hypertension. CONCLUSION: Acute mesenteric venous hypertension and resuscitation-induced gut edema, in the absence of ischemia/reperfusion injury, is associated with delayed intestinal transit and altered gut barrier function.     

Dexamethasone reduces gut permeability in pediatric cardiac surgery

OBJECTIVES: Little attention has been paid to the effect of the systemic inflammatory response syndrome on intestinal dysfunction in the postoperative period. Several proinflammatory cytokines have been reported to increase the permeability of intestinal mucosa in vitro. We investigated the effect of dexamethasone on gut permeability in pediatric patients undergoing cardiac surgery by using the dual sugar permeability test and absorption of 2 other saccharides. METHODS: Thirty-four patients scheduled for cardiac surgery with cardiopulmonary bypass were prospectively randomized to either act as control subjects or to receive dexamethasone (1 mg . kg -1) during induction of anesthesia. Intestinal permeability was measured with 3-O-methyl-D-glucose, D-xylose, L-rhamnose, and lactulose administered orally after induction of anesthesia and 12 and 24 hours later. RESULTS: Lactulose/rhamnose ratios were increased from the outset in both groups (mean 0.57 [95% confidence interval, 0.24-0.91] for the control group and 0.76 [95% confidence interval, 0.35-1.17] for patients receiving dexamethasone). Although the ratios decreased 12 hours (0.29 [95% confidence interval, 0.17-0.42]) and 24 hours later (0.17 [95% confidence interval, 0.08-0.15]) in the dexamethasone group, in the control group there was a rise at 12 hours (0.77 [95% confidence interval, 0-1.64]), with a slight reduction 24 hours later (0.46 [95% confidence interval, 0.06-0.85]). CONCLUSIONS: Infants and children undergoing cardiac surgery with cardiopulmonary bypass show a significant reduction in gut permeability when dexamethasone is used during induction of anesthesia. Dexamethasone does not affect the intestinal barrier at the functional level, as assessed on the basis of 3-O-methyl-D-glucose and D-xylose absorption.     

Effects of early enteral feeding on the prevention of enterogenic infection in severely burned patients

The aim of the study was to analyse the effects of early enteral feeding on the prevention of enterogenic infection in severely burned patients. A total of 22 patients with severe burns were randomly divided into an early enteral feeding group (EF) and a delayed enteral feeding group (DF). The levels of serum endotoxin and TNF-alpha were dynamically detected in the members of both groups, and two unmetabolized sugars (lactulose and mannitol) were orally administered to these patients 1, 3 and 5 days postburn. Intestinal permeability was evaluated by detecting the concentrations of lactulose and mannitol in the urine and the lactulose-mannitol ratio (L/M) ratio. The levels of serum endotoxin and TNF-alpha in severely burned patients were significantly higher than in normal subjects (P<0.01). The endotoxin level was positively related to the TNF-alpha level (rEF=0.93, P<0.01; rDF=0.80, P<0.05). The urinary lactulose levels in both groups were significantly higher than in normal (P<0.01), the urinary mannitol levels showed no obvious changes (P>0.05). The urinary L/M ratios in both groups were significantly higher than in normal subjects (P<0.01). The urinary L/M ratio was positively related to the serum endotoxin level (r=0.95, P<0.01). The urinary lactulose levels and the urinary L/M ratios in the EF group were significantly lower than in the DF group (P<0.01). The levels of serum endotoxin and TNF-alpha in the EF group were significantly lower than in the DF group (P<0.01). It is suggested that intestinal permeability was markedly higher after burns than normal, and was positively related to the gut-derived endotoxemia. Early enteral feeding may decrease intestinal permeability, preserve the intestinal mucosal barrier and have a beneficial effect on the reduction of enterogenic infection.     

重症急性胰腺炎患者早期肠屏障失功能与炎症反应

目的 探讨早期重症急性胰腺炎（SAP）患者肠屏障功能障碍与机体炎症反应的相关性.方法 对2010年1月至2012年12月入选本研究的46例SAP进行研究.在入选后第1天、第3天、第7天和第14天测定患者内毒素水平,尿液中乳果糖与甘露醇之比（L/M）,D-乳酸盐含量,肿瘤坏死因子（TNF）-α,白介素（IL）-6和IL-10水平.结果 早期SAP（最初的14 d内）患者的内毒素含量、L/M、D-乳酸盐浓度及TNF-α、IL-6和IL-10均降低.至第14天均降至最低水平,与第3、7天比较,存在显著差异（P＜0.01）.Spearman Rank Corre1ation分析发现肠屏障功能指标（内毒素含量、L/M、D-乳酸盐浓度）与炎症因子（TNF-α、IL-6和IL-10）之间存在正相关性（P＜0.01）.结论 早期SAP患者存在的炎症反应与肠黏膜屏障失功能有直接相关性.重视早期保护肠黏膜屏障功能是有效治疗SAP的重要因素.     

大鼠失血性休克肠粘膜形态学与功能变化

目的 探讨失血性休克肠缺血/再灌注损伤后,粘膜屏障功能与形态学的变化。方法 制作大鼠失血性休克模型,以休克复苏后0h、1h、3h、6h、12h、24h时间段取回肠组织标本,通过光镜和电镜下进行肠粘膜的形态学改变的观察,包括组织学检查、肠粘膜及绒毛厚度测量、粘膜损伤指数评定;同时在肝门静脉血作内毒素测定及复苏后1h、3h、6h的尿液作乳果糖/甘露醇比值检测以分析肠粘膜屏障功能的改变。结果 肠粘膜损伤主要表现出凋亡、坏死的两种细胞死亡形式。复苏0h组粘膜上皮就发生明显损伤改变,1h进一步加重,3h组出现修复现象,6h部分空肠及回肠绒毛已修复,12h时大部分肠粘膜结构基本恢复正常;内毒素和乳果糖/甘露醇比值在6h组达到高峰,仅24h组才恢复正常。结论 失血性休克缺血-再灌注后,肠粘膜屏障早期受累,表现为回肠粘膜细胞凋亡及坏死的两种损伤形式;肠粘膜具有强大的修复潜能;肠屏障功能的恢复滞后于形态学修复。     

Lack of correlation between failure of gut barrier function and septic complications after major upper gastrointestinal surgery

OBJECTIVE: To determine the influence of abnormal gut barrier function on the risk of septic complications in patients undergoing major resectional surgery for upper gastrointestinal cancer. SUMMARY BACKGROUND DATA: A failure of the gut mucosal barrier to exclude bacteria and endotoxin from the portal and systemic circulation is incriminated in the development of sepsis and multiple organ failure. Although the experimental data is compelling, corroborative evidence from studies in humans is sparse. This study attempted to correlate both preoperative gut barrier dysfunction and the pattern of change after surgery with septic outcome. METHODS: Sixty-eight patients undergoing curative resectional surgery for upper gastrointestinal cancer were monitored for 30-day septic morbidity (intraabdominal abscesses/empyema and pneumonia). Intestinal permeability, serum IgM and IgG anti-endotoxin antibodies (EndoCAb), and serum C-reactive protein were measured before surgery and on postoperative days 1 and 7. RESULTS: Increased intestinal permeability before surgery did not predict septic outcome. Major surgery was associated with increased intestinal permeability and evidence of endotoxin exposure. Comparing sepsis and nonsepsis groups, however, there was no significant difference in intestinal permeability, endotoxin exposure, and the acute phase response after surgery. CONCLUSIONS: This study demonstrates that gut barrier dysfunction occurs after surgery, but the magnitude of change does not differentiate patients in whom sepsis develops and those in whom it does not. Preoperative increased intestinal permeability had no predictive value for sepsis. This study failed to support the thesis that gut barrier dysfunction is directly linked to sepsis.