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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown that gut ischemia/reperfusion (I/R) causes liver dysfunction in vivo (increased [I125]albumin leak, decreased mitochondrial redox potential). Our purpose was to investigate liver dysfunction due to gut I/R in an ex vivo model where oxygen delivery (DO2) could be controlled. Rats underwent laparotomy (sham) or 45 min of superior mesenteric artery (SMA) occlusion (I/R) and 6 hr later the gut and liver were isolated in situ. Pressures were monitored while recirculating blood was perfused via the hepatic artery (2.5 ml/min) for 90 min and the SMA (7.5 ml/min) for the first 30 min, then the portal vein (7.5 ml/min) for 60 min. Both gut and liver DO2 and VO2 (Fick method) were maintained throughout the study period in the gut I/R as well as sham groups. Despite maintenance of liver VO2, however, gut I/R resulted in a marked and persistent reduction in bile flow. In conclusion, dysfunctional bile production after gut I/R is not due to impaired VO2, but rather gut-liver signaling yet to be defined.
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PMID:Gut ischemia/reperfusion-induced liver dysfunction occurs despite sustained oxygen consumption. 161 10

The generation of free oxygen radicals is presumed as a substantial pathogenetic principle in reperfusion injury. Although demonstrated in gut, muscle and kidneys its role in liver reperfusion injury is still under investigation. In an experimental rat model of warm liver ischemia of 60 min and 8 h reperfusion electron resonance spectroscopy assessed the increased generation of free radicals in early reperfusion period, leading to a decrease of polyunsaturated free fatty acids in liver tissue within 15 min of reperfusion. Histologically, single cell death, local and patchy necrosis of hepatic lobuli could be observed after 8 h reperfusion (n = 6). These histologic signs of liver injury could be attenuated by administration of superoxide-dismutase in combination with catalase but not by allopurinol. Best results could be obtained by deferoxamine. This indicates that increased generation of free oxygen radicals in reperfusion is not caused by the known conversion of xanthine-dehydrogenase to -oxidase but is mediated by an increased generation of hydroxyl-radicals, which can be scavenged by deferoxamine.
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PMID:Oxygen radicals in liver ischemia and reperfusion--experimental data. 166 85

Xanthine oxidase (XO)-derived oxygen radicals are thought to play an important role in the intestinal injury resulting from ischemia and reperfusion. In vitro data shows enhanced XO activity in the presence of histamine. Histamine is known to be released during intestinal ischemia and reperfusion. The purpose of this study was to evaluate the relationship between histamine and XO in vivo in intestinal ischemia/reperfusion injury. Using an established model of gut ischemia and reperfusion, portal venous plasma was obtained and assayed for histamine levels, XO activity, and xanthine dehydrogenase (XD) activity following injury. Intestinal ischemia for 120 minutes resulted in a 200% increase in plasma histamine levels (263.4 +/- 36.9 nmol/mL control, v 548.7 +/- 35.1 nmol/mL experimental, P less than .05). Reperfusion for 15 minutes resulted in a further increase in plasma histamine (to 658.3 +/- 33.9 nmol/mL), compared with 120 minutes of ischemia alone. No significant change in plasma XO activity resulted after simple ischemia for 120 minutes. However, XO activity doubled within 15 minutes of reperfusion of the ischemic intestine (6.37 +/- 0.53 nmol O2- per milliliter per minute v 3.12 +/- 0.25 nmol O2- per milliliter per minute, P less than .05). Reperfusion for 60 minutes resulted in the maximal observed increase in plasma XO activity (9.49 +/- 0.67 nmol O2- per milliliter per minute). Analysis of XD activity demonstrated no significant decrease compared with controls until 120 minutes of ischemia and 60 minutes of reperfusion (1.62 +/- 0.49 nmol uric acid per milliliter per minute at 60 minutes of reperfusion, versus 5.02 +/- 0.52 nmol uric acid per milliliter per minute control, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Histamine: a promoter of xanthine oxidase activity in intestinal ischemia/reperfusion. 168 83

Denervation of the gut, resulting in altered bowel function, has been viewed as an impediment to the clinical success of small intestinal transplantation. This study examined the effect of complete extrinsic denervation of the jejunum and ileum on tissue levels of VIP, SP, and 5-HT in a rat model of small intestinal transplantation. Orthotopic total small bowel isograft transplants were performed in 18 Lewis inbred rats. Sham operations consisted of occluding the superior mesenteric artery of 18 Lewis rats for 10 minutes to provide comparable degrees of ischemia. Six rats from each group were sacrificed 1, 2, and 4 weeks following transplantation or sham operation. The jejunum and ileum were removed and extracted in acid for measurement of VIP, SP, and 5-HT by radioimmunoassay. There were no statistically significant differences in the jejunal or ileal content of VIP or 5-HT or the jejunal content of SP between the transplant and sham groups. An initial decrease in ileal SP content at 1 week following transplantation was no longer evident by the fourth week. We conclude that the extrinsic denervation of small intestinal transplantation has minimal effects on the intestinal content of VIP, SP, and 5-HT and should not significantly affect physiologic function controlled by these gastrointestinal hormones.
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PMID:Effect of transplantation on tissue levels of substance P, vasoactive intestinal polypeptide, and serotonin in rat small intestine. 169 79

Reactive oxygen intermediates (ROI) play a major role in the mucosal damage developing during the reperfusion period following intestinal ischemia. We have shown previously that histamine (H) release is related to the ROI generated by xanthine oxidase during intestinal ischemia-reperfusion. The present study sought to determine the possible chain of events leading to H liberation. The artery supplying a segment of the ileum was occluded for 2 hr in 51 anesthetized dogs, and plasma levels of H were determined radioenzymatically in the venous effluent. Catalase was applied to scavenge hydrogen peroxide; dimethylsulfoxide and mannitol were used as hydroxyl radical scavengers; the role of catalytically active iron was assessed by using desferrioxamine. Pretreatment with either catalase or desferrioxamine, but not with dimethyl sulfoxide or mannitol, was effective in reducing the postocclusive H release. The results provide further in vivo evidence that ROI are causative agents in H liberation during reperfusion of the ischemic gut. Hydrogen peroxide can interact with catalytically active iron and generate highly reactive oxidants, which in turn are responsible for H release. The exact nature of these oxidants is still uncertain.
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PMID:Histamine release during intestinal ischemia-reperfusion: role of iron ions and hydrogen peroxide. 172 54

Small bowel obstruction is a common disorder in surgical practice. The major morbidity of bowel obstruction relates to intestinal distension and ischemia. We hypothesized that octreotide, a potent inhibitor of gut secretion, would reduce mortality in a mouse model of lethal small bowel obstruction. C57 mice were anesthetized with urethane and prepared with either proximal jejunal or distal ileal obstruction. After 8 hours, surviving mice were randomized to receive either octreotide (100 micrograms/kg) or saline subcutaneously every 8 hours. Octreotide significantly improved survival in mice with proximal obstruction by life table analysis. Mean survival increased from 31 +/- 3 to 41 +/- 4 hours. In distal obstruction, octreotide treatment resulted in a trend towards improved survival; however, this trend failed to reach statistical significance by life table analysis. The improvement in survival in this mouse model suggests that octreotide may be a valuable adjunct in the treatment of patients with small bowel obstruction.
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PMID:Improvement in survival of mice with proximal small bowel obstruction treated with octreotide. 173 78

Forty dogs were divided randomly into four groups. The portal circulation was reduced to 50%-60% for one hour by partially occluding the superior mesenteric artery (SMA) for the purpose of determining the relationship between the reperfusion injury, bacterial translocation, and multiple system organ failure. Escherichia coli 0111 B4 (1 x 10(10)/kg) was fed to each animal 12 hours before operation. Group I constituted the controls, in which a sham operation was done. The experimental procedure was completed in all the animals of the other three groups. The group-II animals received no further manipulation. Rubia yunnanensis, an antioxidant, was given to the animals in group III. Amikacin was given to the animals in group IV. The results showed that the animals in group II developed bacteremia, hypoxemia, and hypotension compared with the animals in group I. The levels of superoxide dismutase (SOD) in whole blood were markedly lowered in group-II animals, with malondialdehyde (MDA) values significantly elevated after reperfusion when compared with group I. Plasma levels of anaphylatoxin C5a and thromboxane B2 (TXB2) were significantly raised in group-II animals beginning from reperfusion when compared with the animals in group I, group III, and group IV. Pathologic changes in the intestine, liver, and lung were marked only in the group-II animals, including acute necrosis of the intestinal mucosa, granulocyte infiltration, and bacterial invasion of the liver and lung. These results suggested that bowel ischemia and reperfusion may promote gut barrier failure and bacterial translocation, then contribute to the development of MSOF by allowing bacteria or endotoxin normally contained within the gut to reach the portal and systemic circulations, where it fuels the septic process. Oxygen free radicals, anaphylatoxin, and thromboxane may be potential factors in the development of gut barrier failure and MSOF.
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PMID:Bacterial translocation and multiple system organ failure in bowel ischemia and reperfusion. 174 Jul 93

Ischemia and reperfusion injury of the gut mucosa after severe injury have been shown to allow endogenous gastrointestinal tract microorganisms to pass into systemic areas (bacterial translocation); this has been hypothesized as a source of burn-wound contamination. To study this phenomenon, 53 pediatric patients with burns underwent routine fecal culture at the time of admission. These cultures were compared with wound cultures that were obtained at the time of admission and throughout their hospitalization. Patients were grouped according to burn size: Small (1% to 20% total body surface area burned), Moderate (21% to 50%), and Severe (greater than 50%). The incidence of corresponding isolates was determined for each group and compared by analysis of variance. No difference in the frequency of corresponding isolates could be demonstrated between the Small (4.0%) and Moderate (7.7%) groups, whereas the Severe group (53.3%) demonstrated a significantly larger incidence of corresponding isolates (p less than 0.0001). Translocation of gut flora after severe burn injury may account for some instances of burn-wound contamination.
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PMID:Influence of burn size on the incidence of contamination of burn wounds by fecal organisms. 177 3

Portal circulation was reduced to 50-60% for one hour by partial occlusion of the superior mesenteric artery for the purpose of studying the relationship between reperfusion injury, bacterial translocation and multiple system organ failure. Forty dogs were divided randomly into four groups, and 1 x 10(10)/kg E. coli O111B4 were fed to each animal 12 hours before operation. Group I constituted the controls, in which sham operations were performed. The experimental procedure was completed in all the animals of the other three groups. Rubia yunnanensis, an anti-oxidant, was given to group III. Amikacin was given to group IV. The results showed that group II was characterized by bacteremia, hypoxemia, and hypotension as compared with group I. The levels of superoxide dismutase (SOD) in the whole blood were markedly lowered and malondialdehyde (MDA) values significantly elevated in group II after reperfusion compared with group I. Plasma levels of anaphylatoxin C5a and B2 (TXB2) were significantly raised in group II beginning with the reperfusion when compared with groups I, III and IV. Pathological changes in the intestine, liver and lung were remarkable only in group II, including acute necrosis of the intestinal mucosa, granulocyte infiltration, hemorrhage and edema of the lung, degenerative changes of myocardial and hepatic cells, and bacterial invasion of the blood, liver and lung. These results suggested that bowel ischemia and reperfusion may promote gut barrier failure and bacterial translocation, then contribute to the development to multiple system organ failure (MSOF) by allowing bacteria or endotoxin normally contained within the gut to reach the portal and systemic circulations where it fuels the septic process. Oxygen free radicals, anaphylatoxin and thromboxane may be potential factors in the development of gut barrier failure and MSOF.
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PMID:Bacterial translocation and multiple system organ failure in bowel ischemia and reperfusion. 180 29

The effects of intestinal transplantation on the physiologic functions of the gut are not well understood. Our aim was to determine the effect of a large animal model of small intestinal transplantation (disruption of all neural and lymphatic continuity) on selected absorptive functions of the jejunoileum. Seven dogs were studied before and at 1, 4, and 12 weeks after a model of jejunoileal autotransplantation, which avoids confounding factors of immune rejection, immunosuppression, and harvest ischemia. Jejunal function was assessed by quantitative [3H]-folate and D-xylose absorption and ileal function by quantitative 57Co-vitamin B12 absorption. The role of lymphatic continuity was assessed by fecal fat recovery following 5 days of a controlled, high fat diet (75 g/day). All dogs developed a profuse, watery diarrhea that persisted for 6 to 12 weeks and lost about 15% body weight; however, absorption of D-xylose, folate, and vitamin B12 was unaffected at any time point. Fat absorption postoperatively was only mildly abnormal (less than or equal to 8 g/day) at all time points in five of seven dogs despite complete lymphatic disruption. We concluded that jejunoileal autotransplantation does not markedly affect these specific jejunoileal absorptive functions. Fat absorption in most dogs surprisingly remains almost normal. Anatomic and physiologic consequences of intestinal transplantation do not appear to induce global abnormalities in all absorptive functions in the nonrejecting jejunoileum.
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PMID:Jejunal and ileal absorptive function after a model of canine jejunoileal autotransplantation. 188 Nov 37


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