Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adult Respiratory Distress Syndrome (ARDS) is a feared complication of trauma or sepsis, characterized by an interstitial and alveolar edema due to increased pulmonary microvascular permeability. In ARDS polymorphonuclear granulocytes (PMN) aggregate and accumulate in the pulmonary microvessels and activation of the complement system, especially C5a, is suggested to be of importance supporting this aggregation. Such complement activated PMN can increase vascular permeability, probably by initiating endothelial cell (EC) damage. Addition of PMN and C5a to cultured EC monolayers in vitro produced both morphological and functional EC damage. A similar EC damage could be reproduced in the absence of white cells by exposing EC monolayers to oxygen free radicals induced by xanthine and xanthine oxidase or hydrogen peroxide. High dose corticosteroid (HDC) administration has been advocated in shock and ARDS and it has been experimentally demonstrated that methylprednisolone or hydrocortisone at a concentration corresponding approximately to a dose of 30 mg/kg i.v. inhibited both PMN aggregation and adhesion to the endothelium. On the other hand, no effect of HDC on PMN thromboxane synthesis or cell membrane morphology alterations was found. It has been suggested that HDC increases PMN hydrophobicity and thus reduces the tendency of the white cells to adhere to the endothelium of the microvasculature. Furthermore, it has been demonstrated that HDC can inhibit PMN production of oxygen free radicals. Platelets seem to play a role in ARDS. Serotonin released from platelets increased the cytotoxic effect of PMN on EC more than 100% in vitro, and activated PMN seemed to recruit platelets and release vasoactive substances. On the other hand, platelet serotonin enhanced the adhesion of complement stimulated PMN to EC, thus creating a vicious circle. To conclude, complement activated PMN aggregate and adhere to the pulmonary microvascular EC which are injured by e.g. PMN-generated oxygen free radicals. Platelet aggregation and release of serotonin augments this injury and activated PMN probably stimulate platelet aggregation and release. Agents capable of diminishing PMN activation and aggregation, e.g. HDC, might be of value in attenuating these cell-cell interactions in ARDS.
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PMID:High dose corticosteroids and cell-cell interactions. 391 7

The effect of the antioxidant N-acetyl-L-cysteine was studied in a model of polymicrobial sepsis induced in CD-1 mice by cecal ligation and puncture. N-Acetyl-L-cysteine significantly improved survival during the 6 days following sepsis induction and caused lower liver toxicity. This effect was not related to free radicals generated by xanthine oxidase which was significantly induced in liver after cecal ligation and puncture. A specific inhibitor of xanthine oxidase, allopurinol, significantly reduced this enzyme and reduced the early survival rate. The effect of N-acetyl-L-cysteine was not related either to a reduction in tumor necrosis factor production or to a modulation of nitrites or to liver glutathione content. These results show that the induction of xanthine oxidase is not deleterious in this model of sepsis and suggest that N-acetyl-L-cysteine works as a direct antioxidant and scavenger of free radicals generated from other sources.
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PMID:Effect of N-acetyl-L-cysteine on sepsis in mice. 779 76

The commonly used immunosuppressive regimen after orthotopic heart transplantation consists of cyclosporine (CsA), azathioprine (AZA), and steroids. Although AZA therapy is generally regarded as unproblematic, its use can be associated with severe side effects, particularly myelosuppression. Since AZA is a prodrug, which must first be metabolized to its active metabolites, AZA therapy, in contrast to CsA therapy, cannot be controlled by measuring blood levels of this drug. Because of the myelosuppressive properties of the AZA metabolites, the 6-thioguanine nucleotides (6-TGN), the white blood cell count is usually monitored in patients on AZA therapy, and AZA is discontinued if neutropenia appears. In a group of 20 consecutive heart recipients, 6-TGN concentrations ranged from < 30 to 2,211 pmol/8 x 10(8) red blood cells (RBCs); levels < or = 450 pmol/8 x 10(8) RBCs were not associated with AZA-induced myelosuppression. Three cases of neutropenia were experienced, two of them with a fatal outcome. One patient died in septicemia owing to total myelosuppression. In this case an excessively high erythrocyte 6-TGN concentration (2,211 pmol/8 x 10(8) RBCs) was associated with a complete deficiency of thiopurine methyltransferase (TPMT), one of the main AZA detoxifying enzymes. The second patient, who had high RBC TPMT activity, developed neutropenia during rehabilitation, and AZA was withdrawn. Coincidentally, in this case the CsA blood level was only 132 g/L, and the RBC 6-TGN level was very low (maximum 46 pmol/8 x 10(8) RBCs). This patient rapidly developed cardiogenic shock with clinical signs of acute rejection and was given a second transplant on an emergency basis, but finally died from rejection of the second graft. Retrospectively, it was determined that neutropenia in this patient was not related to AZA toxicity. A high 6-TGN level (698 pmol/8 x 10(8) RBCs) was also seen in a third patient with mild neutropenia, who required allopurinol, an inhibitor of xanthine oxidase, the other major detoxifying enzyme for AZA. In this patient AZA therapy could be individually adapted by RBC 6-TGN monitoring. Based on our experience, we suggest that RBC 6-TGN monitoring allows for better individualization of treatment with AZA and may help avoid fatal complications.
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PMID:Should 6-thioguanine nucleotides be monitored in heart transplant recipients given azathioprine? 873 60

Nitric oxide release is induced in many cells, including vascular endothelium, as part of the host response to inflammation. Nitric oxide synthase activity is increased in patients with sepsis, associated with increased oxidant demands and decreased antioxidant protection. We used a human vascular endothelial cell line to investigate the influence of antioxidants on nitric oxide synthase activity. Cells were cultured to confluence and incubated with interferon gamma, tumor necrosis factor, and lipopolysaccharide in the combined presence of the antioxidants ascorbic acid, Trolox, catalase, or superoxide dismutase, singly and in combination, for 48 h. Additionally, some cells were incubated with hypoxanthine-xanthine oxidase or a nitric oxide donor. Nitric oxide synthase activity was upregulated by cytokine exposure (p < .0005). Ascorbic acid and superoxide dismutase/ catalase resulted in decreased enzyme activity (p < .05). Superoxide anion release from xanthine oxidase caused increased activity (p < .05) and exogenous nitric oxide tended to suppress synthase activity. We suggest that antioxidants scavenge superoxide anion, enabling feedback inhibition of nitric oxide synthase activity by nitric oxide, and thus reducing enzyme activity. Exogenous nitric oxide also has a similar effect. Superoxide generation suppresses this feedback inhibition. This study has important implications in patients with sepsis in whom nitric oxide synthase inhibitor therapy is currently under investigation.
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PMID:Regulation of nitric oxide synthase activity in cultured human endothelial cells: effect of antioxidants. 879 Oct 97

Acute respiratory distress syndrome in adults (ARDS) carries a high mortality. Patients with ARDS experience severe oxidative stress from neutrophil activation, and from treatment with high inspired oxygen concentrations (F(I)O2). Oxidative stress arises from an increased generation of reactive oxygen species (ROS) which overwhelm existing antioxidant defenses. Patients who do not survive ARDS sustain much greater levels of oxidative molecular damage, suggesting that they are less able to protect themselves against increased oxidative stress. We measured plasma levels of pro-oxidant substrates for xanthine oxidase, namely hypoxanthine and xanthine, and correlated them with the loss of plasma protein thiol groups. All patients with ARDS had higher levels of hypoxanthine (37.48 +/- 3.1 microM in nonsurvivors, 15.24 +/- 2.09 microM in survivors) compared with patients undergoing pulmonary resection (9.22 +/- 1.89 microM), patients in intensive care with sepsis but no lung injury (1.12 +/- 0.69 microM) and normal healthy control subjects (1.43 +/- 0.38 microM). The difference in plasma hypoxanthine levels between survivors and nonsurvivors of ARDS was highly significant (p < 0.001) and showed a negative correlation with loss of protein thiol groups. Xanthine levels were also higher in patients with ARDS but were not significantly different between ARDS survivors and nonsurvivors. Nonsurvivors of ARDS appear to experience higher levels of oxidative stress and damage than do survivors.
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PMID:Plasma hypoxanthine levels in ARDS: implications for oxidative stress, morbidity, and mortality. 903 82

Decreases in the alveolar O2 tension commonly follow gram-negative bacteremic shock that progresses to the acute respiratory distress syndrome (ARDS). To examine the effects of alveolar hypoxia and reoxygenation (H/R) on postbacteremic pulmonary cytokine expression, lungs from Sprague-Dawley rats (n = 43) were perfused over 180 min after hematogenous infection with 10(9) live Escherichia coli serotype O55:B5 (EC) or infusion of 0.9% NaCl (NS). Compared with normoxic EC and NS controls, EC + H/R and NS + H/R lungs received 90 min of constant-flow hypoxia followed by 60 min of reoxygenation. Perfusates were cultured and analyzed for TNF-alpha, IL-1alpha, IL-1beta, and PGE2 while monitoring pulmonary artery pressure (Ppa). Changes in the filtration coefficient (Kf) were evaluated at 180 min when cytokine mRNA levels were assessed in lung homogenates. Transcripts of the anti-inflammatory cytokine TGF-beta1 and of inducible cyclooxygenase (COX-2) were similarly analyzed. For equivalent EC clearance, Ppa, and Kf as in normoxic EC, postbacteremic H/R increased TNF-alpha gene expression and doubled the export of TNF-alpha from the lungs, an effect not blocked by allopurinol. IL-1alpha transcripts were also increased in EC + H/R versus EC lungs, in contrast to the lack of change in IL-1beta, TGF-beta, or COX-2 mRNA levels, or in cell-associated or circulating IL-1beta and PGE2. Thus, gram-negative bacteremic lung infection and secondary alveolar H/R upregulate the expression of specific inflammatory cytokines compared with pulmonary infection under normoxic conditions, independently of xanthine oxidase-induced O2 radicals. These findings identify the alveolar PO2 as a potent immunomodulatory signal whose reductions early after gram-negative sepsis may enhance lung inflammation in ARDS.
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PMID:Upregulation of postbacteremic TNF-alpha and IL-1alpha gene expression by alveolar hypoxia/reoxygenation in perfused rat lungs. 947 82

The isoprostanes are a group of biologically active arachidonic acid metabolites initially thought to be formed under conditions of oxidative stress and independently of cyclooxygenase. However, recent studies have demonstrated isoprostane production under conditions in which cyclooxygenase is intentionally activated/induced. Here we describe for the first time formation of isoprostanes by human vascular cells via independent pathways of oxidative stress and cyclooxygenase induction. We compared the release of the isoprostane with that of the traditional prostaglandin, prostaglandin E2. Cyclooxygenase-2 induction was confirmed by Western blot. When cells were stimulated with cytokines, the release of isoprostanes was inhibited by the cyclooxygenase-1 and -2 inhibitor indomethacin as well by as the cyclooxygenase-2 selective inhibitor L-745,337. However, treatment of cells with the superoxide-producing enzyme xanthine oxidase also resulted in isoprostane release, which was not affected by cyclooxygenase inhibition, unlike PGE2 release under the same condition. Thus, two independent pathways relating to oxidative stress and cyclooxygenase-2 induction form isoprostanes. These findings may have particular importance in diseases such as sepsis and ARDS in which oxidant stress occurs and cyclooxygenase is induced.
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PMID:Isoprostanes and PGE2 production in human isolated pulmonary artery smooth muscle cells: concomitant and differential release. 1033 84

The purpose of this review-hypothesis is to discuss the literature which had proposed the concept that the mechanisms by which infectious and inflammatory processes induce cell and tissue injury, in vivo, might paradoxically involve a deleterious synergistic 'cross-talk', among microbial- and host-derived pro-inflammatory agonists. This argument is based on studies of the mechanisms of tissue damage caused by catalase-negative group A hemolytic streptococci and also on a large body of evidence describing synergistic interactions among a multiplicity of agonists leading to cell and tissue damage in inflammatory and infectious processes. A very rapid cell damage (necrosis), accompanied by the release of large amounts of arachidonic acid and metabolites, could be induced when subtoxic amounts of oxidants (superoxide, oxidants generated by xanthine-xanthine oxidase, HOCl, NO), synergized with subtoxic amounts of a large series of membrane-perforating agents (streptococcal and other bacterial-derived hemolysins, phospholipases A2 and C, lysophosphatides, cationic proteins, fatty acids, xenobiotics, the attack complex of complement and certain cytokines). Subtoxic amounts of proteinases (elastase, cathepsin G, plasmin, trypsin) very dramatically further enhanced cell damage induced by combinations between oxidants and the membrane perforators. Thus, irrespective of the source of agonists, whether derived from microorganisms or from the hosts, a triad comprised of an oxidant, a membrane perforator, and a proteinase constitutes a potent cytolytic cocktail the activity of which may be further enhanced by certain cytokines. The role played by non-biodegradable microbial cell wall components (lipopolysaccharide, lipoteichoic acid, peptidoglycan) released following polycation- and antibiotic-induced bacteriolysis in the activation of macrophages to release oxidants, cytolytic cytokines and NO is also discussed in relation to the pathophysiology of granulomatous inflammation and sepsis. The recent failures to prevent septic shock by the administration of only single antagonists is disconcerting. It suggests, however, that since tissue damage in post-infectious syndromes is caused by synergistic interactions among a multiplicity of agents, only cocktails of appropriate antagonists, if administered at the early phase of infection and to patients at high risk, might prevent the development of post-infectious syndromes.
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PMID:Can we learn from the pathogenetic strategies of group A hemolytic streptococci how tissues are injured and organs fail in post-infectious and inflammatory sequelae? 1049 63

Septicaemia is a major threat to survival during the early stages of life. There are several reports that suggest that reactive oxygen species (ROs) play a role in a wide variety of diseases. We estimated the activity of xanthine oxidase (XO), malondialdehyde (MDA) content, creatine phosphokinase (CPK) activity, activities of key enzymatic antioxidants, such as superoxide dismutase (SOD), glutathione peroxidase (GPx) and peroxidase (PO), and non-enzymatic antioxidants, viz. uric acid (UA) and albumin (ALB), in 30 neonates with sepsis and 20 age-matched controls. The babies were categorized as preterm/term, early onset/late onset, and shock/without shock, as per clinical and laboratory investigations. The study was carried out to evaluate the status of antioxidant enzymes and non-enzymatic antioxidants with a view to suggesting the introduction of antioxidant therapy in neonatal sepsis. The activities of serum XO, CPK, SOD and GPx, and the content of MDA were found to be significantly elevated in the neonates with sepsis when compared with controls. Conversely, the activity of PO and the levels of UA and ALB were decreased. The septic, full-term neonates registered significantly higher CPK activity (70%) than the preterm septic neonates. However, infants with late-onset and shock sepsis had a significant decrease in CPK activity (p < 0.05) compared with their corresponding sub-groups. Likewise, UA levels were found to be 28% depressed (p < 0.05) in the babies with late-onset sepsis and 51% increased (p < 0.001) in babies with shock compared with their respective sub-groups. Neonates with septic shock also registered a significant elevation in GPx activity (28%) compared with those without shock. This study suggests increased production of ROs in neonates with sepsis, as evidenced by the positive regulation of XO, SOD and GPx activity. The elevation of antioxidant enzymes, however, was not so effective as to protect from cellular damage and thereby result in higher MDA production. It is evident that antioxidant therapy might be useful in the management of neonates with sepsis but further detailed clinico-biochemical investigations are required to define effective antioxidant therapy.
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PMID:Alterations in antioxidant status during neonatal sepsis. 1082 10

Reductions in hepatic O(2) delivery are common early after gram-negative bacteremic sepsis owing to cardiopulmonary dysfunction and derangements in sinusoidal perfusion. Although gram-negative endotoxin and cellular hypoxia independently enhance activation of nuclear factor-kappaB (NF-kappaB) via generation of reactive O(2) species (ROS), the combination of these stimuli downregulates hepatic TNF-alpha gene expression. Here we tested the hypothesis that hypoxic suppression of postbacteremic TNF-alpha gene expression is transcriptionally mediated by reduced activation of NF-kappaB. Buffer-perfused rat livers (n = 52) were studied over 180 min after intraportal infection at t = 0 with 10(9) live Escherichia coli (EC), serotype O55:B5, or 0.9% NaCl controls under normoxic conditions, compared with 0.5 h of constant-flow hypoxia (PO(2) approximately 41 +/- 7 Torr) beginning at t = 30 min, followed by 120 min of reoxygenation. In parallel studies, tissue was obtained at peak hypoxia (t = 60 min). To determine the role of xanthine oxidase (XO)-induced ROS in modulating NF-kappaB activity after hypoxia/reoxygenation (H/R), livers were pretreated with the XO inhibitor allopurinol, with results confirmed in organs of tungstate-fed animals. Electrophoretic mobility shift assays were performed on nuclear extracts of whole liver lysates using (32)P-labeled oligonucleotides specific for NF-kappaB. Compared with normoxic EC controls, hypoxia reduced postbacteremic NF-kappaB nuclear translocation and TNF-alpha bioactivity, independent of reoxygenation, tissue levels of reduced glutathione, or posthypoxic O(2) consumption. XO inhibition reversed the hypoxic suppression of NF-kappaB nuclear translocation and ameliorated decreases in cell-associated TNF-alpha. Thus decreases in hepatic O(2) delivery reduce postbacteremic nuclear translocation of NF-kappaB and hepatic TNF-alpha biosynthesis by signaling mechanisms involving low-level generation of XO-mediated ROS.
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PMID:Brief hypoxic stress suppresses postbacteremic NF-kappaB activation and TNF-alpha bioactivity in perfused liver. 1089 70


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