Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There are still controversies concerning the concept and diagnosis of multiple systems organ failure (MSOF), since the term does not precisely define its true nature, and its differential diagnosis with other irrelevant clinical conditions, such as senile dysfunction of organs, agonal state, etc, remains unclarified. Our studies on both human burn patients and rat model by means of electron spin resonance (ESR) showed that there was an excessive generation of free oxygen radicals resulting in lipid peroxidation of cell membrane of various tissues. The intestine seemed to be particularly sensitive to hypoperfusion-reperfusion injury, as diamine oxidase activity of the ileum was lowered and translocation of bacteria occurred, indicating failure of intestinal mucosal barrier function. Concomitant determinations of plasma endotoxin (LPS) and tumor necrosis factor alpha (TNFa) levels showed significant elevation, especially in patients who finally developed MSOF. The data suggested that intestinally derived bacteria and/or LPS exacerbate the systemic responses initiated by ischemia reperfusion injury and the presence of large amounts of devitalized tissue. Early diagnosis is important in order to improve the prognosis. However, current criteria of diagnosis for MSOF do not conduce to an early diagnosis, as they only describe the end stage manifestations, while our therapeutic strategy should be directed against different levels of initiators, systemic mediators, and effectors of injury. Therefore, it is important to emphasize the role of septic responses in the development of the syndrome. We propose that the name of the syndrome be changed to "sepsis with organ dysfunction" or "mediator injury of organs".
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PMID:The concept and diagnosis of multiple systems organ failure. 780 37

Endotoxemia occurs when intestinal ischemia allows bacterial lipopolysaccharide to translocate from colonic flora into the bloodstream, which triggers release of cytokines that can cause hypotension, rigors, fever, shock, and even death. Recently, blood endotoxin levels were shown to be higher in athletes needing medical attention (330 pg.ml-1) than in their competitors with similar performances (81 pg.ml-1). Though there were no data showing that these athletes had elevated core temperatures or severe illness, speculation followed that endotoxin may play a causal role in heat stroke. We examined the relationship between endotoxemia and mild post-exertional illness in 39 cyclists after a 100-mile ride. Thirteen cyclists had at least one of the following: orthostatic hypotension, rigors, nausea, vomiting, diarrhea, or syncope. Only 2/26 case-controls had any of these symptoms. Data were collected on vital signs, hemoglobin, sodium, creatine kinase, creatinine, and uric acid. Endotoxin titer was determined by chromogenic assay; tumor necrosis factor alpha (TNF-alpha) titer was determined by ELISA. One ill cyclist had an endotoxin level of 330 pg.ml-1, one control had an endotoxin level of 150 pg.ml-1, but endotoxin level was < or = 64 pg.ml-1 in all others. Comparison of pre- and post-ride data showed that controls increased creatine kinase activity (154 +/- 34 vs 561 +/- 191 IU.dl, P < 0.05), creatinine concentration (1.5 +/- 0.0 vs 1.6 +/- 0.0 mg.dl-1, P < 0.05), and uric acid concentration (5.4 +/- 0.3 vs 6.3 +/- 0.3 mg.dl-1, P < 0.05). Ill cyclists had lower serum sodium than post-ride controls (138 +/- 2 vs 142 +/- 0.6 mEq.l-1, P < 0.05), but there were no differences between groups in CK, creatinine, or uric acid. These findings suggest that endotoxemia may complicate, but does not cause mild post-exertional illness in cyclists.
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PMID:Exercise-associated collapse in cyclists is unrelated to endotoxemia. 853 21

The liver is highly susceptible to a number of pathological insults, including ischemia/reperfusion injury. We have previously employed an animal model of hepatic ischemia/reperfusion injury, and have shown that this injury induces the production and release of hepatic-derived tumor necrosis factor alpha (TNF-alpha), which mediates, in part, local liver injury following hepatic reperfusion. In the present study, we have extended these previous observations to assess whether an interrelationship exists between TNF-alpha and the neutrophil chemoattractant/activating factor, epithelial neutrophil activating protein, that may account for some of the pathology of neutrophil-mediated ischemia/reperfusion-induced liver injury. We observed that hepatic ischemia/reperfusion injury leads to: (1) a coincident increase in hepatic neutrophil sequestration, elevated serum alanine aminotransferase (ALT) levels, and hepatic production of epithelial neutrophil activating protein; (2) passive immunization with neutralizing antibodies to TNF-alpha resulted in significant suppression of hepatic-derived epithelial neutrophil activating protein; and (3) neutralization of epithelial neutrophil activating protein by passive immunization significantly attenuated neutrophil sequestration in the liver and serum ALT levels. These findings support the notion that local expression of hepatic epithelial neutrophil activating protein produced in response to TNF-alpha is an important mediator of the local neutrophil-dependent hepatic injury associated with hepatic ischemia/reperfusion.
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PMID:The role of cytokine networks in the local liver injury following hepatic ischemia/reperfusion in the rat. 861 30

Animal studies suggest that acute phase reactant cytokines and polymorphonuclear leukocytes (PMN) may play a critical role in ischemia-reperfusion injury. To evaluate whether similar mechanisms are operative in human liver, six cirrhotic and nine noncirrhotic patients undergoing right hepatectomy were randomized for utilization of hepatic vascular exclusion (HVE) as a model of ischemia-reperfusion injury. Portal and systemic levels of acute reactant cytokines (interleukin 6 [IL-6], interleukin 1 [IL-1], tumor necrosis factor alpha [TNF-alpha]) and neutrophil adhesion in serial liver biopsy specimens were studied. Correlations among mediators, leukocyte adhesion, and markers of liver injury were also evaluated. Hepatic vascular exclusion resulted in substantial and reproducible changes in portal and arterial IL-6 levels in both cirrhotic and noncirrhotic patients. Portal and systemic cytokine levels were comparable in most instances, whereas levels were usually higher in cirrhotic patients than in noncirrhotic patients. Negative correlations were found between IL-6 levels at the time of reperfusion and later TNF-alpha levels. IL-6 levels correlated negatively with numerous markers of hepatocellular injury and the number of postoperative complications. Hepatic vascular exclusion increased neutrophils adhesion after reperfusion in cirrhotic patients but not in noncirrhotic patients. In cirrhotic patients, the degree of leukocyte adhesion after reperfusion correlated with several postoperative markers of liver injury. This study in humans shows that acute reactant cytokines are released during liver ischemia and, interestingly, that IL-6 levels strongly correlate with clinical and laboratory measures of injury. Further studies to evaluate possible causal relationship with hepatic injury are warranted, with emphasis on the role of IL-6 and PMN adhesion.
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PMID:Acute reactant cytokines and neutrophil adhesion after warm ischemia in cirrhotic and noncirrhotic human livers. 867 64

Although platelet-activating factor (PAF) is implicated as an important mediator in the pathogenesis of hepatic ischemia-reperfusion (IR) injury, the precise mechanism of its action has not been studied. We examined the hypothesis that PAF may influence neutrophils by promoting the production of tumor necrosis factor alpha (TNF-alpha) and cytokine-induced neutrophil chemoattractant (CINC), a member of the interleukin-8 (IL-8) family, and may be associated with liver and lung injury during the early phase of reperfusion after total hepatic ischemia. Rats pretreated with a specific PAF receptor antagonist exhibited suppression of the increase in plasma TNF-alpha and CINC levels, as well as the priming of peripheral neutrophils for superoxide production after reperfusion when compared with animals pretreated with physiological saline. These effects resulted in a reduction of plasma liver enzymes and of hepatic and pulmonary neutrophil sequestration, as well as an increased survival rate. There was a strong correlation between the time course of CINC release and hepatic or pulmonary neutrophil sequestration. We concluded that PAF activates neutrophils, either directly or by promoting the production of TNF-alpha and CINC, and is involved in hepatic IR injury.
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PMID:Involvement of platelet-activating factor in cytokine production and neutrophil activation after hepatic ischemia-reperfusion. 867 90

The surface expression of beta2-integrins was investigated in leukocytes from patients undergoing ischemia induced by tourniquet application for elective hand surgery. Blood samples were obtained before initiation, at the end of ischemia, and after 15 minutes of reperfusion from ischemic and contralateral arms of five patients. Comparable expression of CD18, CD11a, CD11b, and CD11c could be detected by immunofluorescence in leukocytes from samples drawn from either arm before tourniquet application. In contrast, a significant increase in the expression of CD18 was detectable in monocytes, granulocytes, and lymphocytes from the ischemic arm compared with that in the nonischemic contralateral control, at the end of the ischemia time (80 +/- 16 minutes). A significantly increased expression of CD11b, but not CD11a or CD11c, determinants was also observed in granulocytes and monocytes. Concomitantly, a significant reduction in the percentages of granulocytes in samples from ischemic areas was detectable. After 15 minutes of reperfusion, differences in the expression of these adhesion molecules were no longer significant. The expression of the genes encoding interleukins IL-1alpha, IL-1beta, and IL-6 and tumor necrosis factor alpha (TNFalpha) proinflammatory cytokines was also studied by reverse polymerase chain reaction (rPCR) in peripheral blood mononuclear cells (PBMCs) obtained from the same samples in three patients. IL-1beta or IL-6 gene expression was never observed. Expression of IL-1alpha and TNFalpha genes, as detected in two patients, was not related with induction of ischemia. However, in these patients expression of one or both these genes was observed in samples derived from the ischemic but not the control arm after 15 minutes of reperfusion. These data document that overexpression of adhesion molecules and sequestration of leukocytes take place following short ischemia times, as routinely applied clinically for minor surgical procedures.
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PMID:Increased surface expression of CD18 and CD11b in leukocytes after tourniquet ischemia during elective hand surgery. 899 75

The injury resulting from cold ischemia and warm reperfusion during liver transplantation is a major clinical problem that limits graft success. Kupffer cell activation plays a pivotal role in reperfusion injury, and Kupffer cell products, including free radicals and tumor necrosis factor alpha (TNF-alpha), are implicated as damaging agents. However, the second messengers and signaling pathways that are activated by the stress of hepatic ischemia/reperfusion remain unknown. The purpose of this study is to assess the activation of the three known vertebrate mitogen activated protein kinase (MAPKs) and the activating protein 1 (AP-1) transcription factor in response to ischemia and reperfusion in the transplanted rat liver. There was a potent, sustained induction of c-jun N-terminal kinase (JNK), but not of the related MAPKs extracellular signal-regulated kinases (ERK) or p38, upon reperfusion after transplantation. TNF-alpha messenger RNA (mRNA) levels and transcription factors AP-1 and nuclear factor-kappaB (NF-kappaB) were induced in the liver after 60 minutes of reperfusion. Finally, there was an elevation of ceramide, but not diacylglycerol or sphingosine, in the transplanted liver. Ceramide is a second messenger generated by TNF-alpha treatment and is an activator of JNK. Because JNK activation preceded the elevations in ceramide and TNF-alpha mRNA, these results suggest that increased hepatic TNF-alpha and ceramide may perpetuate JNK induction, but that they are not the initiating signals of JNK activation during reperfusion injury in the transplanted liver.
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PMID:Reperfusion after liver transplantation in rats differentially activates the mitogen-activated protein kinases. 914 52

The mechanisms that cause carotid atherosclerotic plaque to become symptomatic remain unclear. Evidence suggests that mediators of inflammation not only are instrumental in the formation of plaque but also may be involved in the rapid progression of atheromatous lesions, leading to plaque fissuring and intraluminal thrombosis. This article reviews the current evidence for the role of inflammatory mediators in atherosclerotic plaque production and maturation. It also includes studies performed in our laboratory to determine if known components of the inflammatory pathway, including cytokines and leukocyte adhesion molecules, are preferentially expressed on symptomatic versus asymptomatic carotid plaques. Carotid plaques from symptomatic and asymptomatic patients undergoing carotid endarterectomy with lesions of greater than 70% stenosis were snap-frozen and stored at -70 degrees C until analysis. Immunofluorescent studies were performed to measure endothelial expression of intercellular adhesion molecule-1 (ICAM-1). ICAM-1 expression was measured in a blinded fashion as percent of luminal endothelial surface of plaque sections. In situ hybridization also was performed to measure expression of message for tumor necrosis factor alpha (TNF-alpha) and ICAM-1 in the plaque by comparing mean optical density between the symptomatic and asymptomatic patients. There was increased expression of ICAM-1 on the endothelial surface in high-grade regions (28%) versus low-grade regions (11%), of plaques from symptomatic patients. There was also a trend toward greater expression of ICAM-1 in the high-grade region of symptomatic plaques versus the high-grade region of asymptomatic plaques. In situ hybridization revealed increased mRNA for TNF-alpha and ICAM-1 in the body of the plaque, preferentially in the high-grade region of plaques from symptomatic patients. The data obtained suggest that a local increase of endothelial inflammatory mediator expression correlates with the clinical setting of thromboembolic ischemia and may play a role in conversion of atheromatous plaque to a prothrombotic state. The data also indicate that this line of investigation deserves further exploration because it may be useful in identifying new mechanisms in patients at risk for stroke and in suggesting possible novel strategies for intervention.
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PMID:Expression of inflammatory mediators and adhesion molecules in human atherosclerotic plaque. 937 Nov 43

During the ischemia/reperfusion phenomenon, adhesion molecules seem to play a critical role in the recruitment of neutrophils to sites of eventual tissue injury. E-selectin is an endothelium-derived molecule that mediates adhesion of neutrophils to activated endothelial cells. In vitro expression of E-selectin, after exposure to stimuli such as endotoxin, interleukin 1, or tumor necrosis factor alpha is maximal at 4 to 6 h, followed by a decline toward basal levels at 24 to 48 h. Characterizing the temporal expression of E-selectin in an in vivo model of skin flap ischemia-reperfusion would help to determine the optimal approach to eventual pharmacologic blockade. This intervention may prove therapeutically beneficial in attenuating flap injury. This study, using the standard porcine buttock skin flap model, was designed to evaluate immunohistochemically the expression of E-selectin in flaps subjected to (1) arterial ischemia (8 h)-reperfusion (18 h), (2) venous ischemia (8 h)-reperfusion (18 h), and (3) distal ischemia (26 h). Four flaps were examined per group, with 8 biopsies being collected sequentially over the 26-h study period from each flap. Blinded, semi-quantitative histologic scoring revealed the following results: (1) E-selectin is absent in normal porcine skin; (2) with arterial ischemia/reperfusion, E-selectin expression in flaps was maximal at 1 h of reperfusion, declining thereafter; (3) with venous ischemia/reperfusion, E-selectin expression peaked during the first hour of ischemia, with subsequent decline; and (4) within a flap designed to sustain distal ischemia, E-selectin expression is relatively more intense in regions of the flap distant from the vascular pedicle, and maximal at 6 h after flap elevation. Our conclusion, therefore, is that the kinetics of E-selectin expression within the tissues of porcine skin flaps differs depending on the type of ischemic insult sustained. Interpretation of these findings, correlating possible pathophysiologic differences in the different models of ischemia, is offered.
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PMID:Kinetics of E-selectin expression in surgical flaps. 951 61

Interleukin-6 (IL-6) is an acute reactant cytokine with anti-inflammatory properties, which has been found to prevent injury in a model of acute hepatitis in mice through downregulation of tumor necrosis factor alpha (TNF-alpha); to correlate inversely with markers of hepatocellular injury in patients with liver ischemia; and to initiate liver regeneration in mice. In this study, we investigated the role of IL-6 in rodent models of hepatic warm ischemia/reperfusion (WI/Rp) injury. IL-6-deficient mice (-/-) were subjected to hepatic WI and compared with C57BL/6 mice, as well as IL-6 -/- mice pretreated with recombinant IL-6 (rIL-6). The effects of rIL-6 following various periods of ischemia were further studied in models of hepatic ischemia in rats. IL-6 -/- mice had increased reperfusion injury as assessed by transaminase levels and a tissue necrosis scoring system when compared with controls, an effect prevented by pretreatment with rIL-6. Similarly, rats pretreated with rIL-6 had reduced reperfusion injury and better survival than controls in each respective WI group. Tissue TNF-alpha expression measured by Northern blot analysis and serum C-reactive protein (CRP) levels, a marker of inflammation, were significantly reduced in animals pretreated with rIL-6. Administration of antibodies to TNF-alpha reproduced the beneficial effect of rIL-6. Hepatocyte proliferation, as assessed by a scoring method for mitotic index and proliferating nuclear cell antigen staining, was markedly increased in rIL-6-treated rats when compared with controls. In conclusion, this study suggests that IL-6 could play an important role in limiting hepatic warm ischemia/reperfusion (WI/Rp) injury, probably through its anti-inflammatory properties, modulation of TNF-alpha, and/or promotion of liver regeneration. rIL-6 might become an important cytokine in clinical situations associated with WI/Rp injury.
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PMID:Interleukin-6 protects liver against warm ischemia/reperfusion injury and promotes hepatocyte proliferation in the rodent. 939 92


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