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)

We have studied the behaviour of total protein S, free protein S, protein C and C4b-binding protein fifteen neonates with severe infections, eight with septic shock and in a group of ten healthy newborns. Protein C was decreased in shock and septic patients, but only the shock group showed significant differences compared to normal neonates. Total protein S was normal in both groups of patients, although free protein S had significantly lower values in shock and nonshock infants. C4b-binding protein was higher than normal in septic and shock patients compared to the control group. Decreased values of protein C and free protein S can be explained by the activation of coagulation and their subsequent consumption. On the other hand, the increased levels of C4b-binding protein can affect the distribution of protein S in plasma, producing a shift in protein S to the complexed inactive form. These findings can contribute to an increased risk of microthrombosis during neonatal sepsis.
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PMID:Protein C, protein S and C4b-binding protein in neonatal severe infection and septic shock. 138 81

To obtain quantitative information on the in vivo activation of the protein C system during the acute phase of sepsis, several components of the protein C pathway were studied in 18 patients. Blood samples were obtained one day after diagnosis (day 1) and, in 11 patients, also on the fourth and tenth days after diagnosis (days 4 and 10). On day 1, patients showed laboratory signs of haemostatic alterations such as positive fibrinogen/fibrin degradation products, and increased thrombin:antithrombin-III (TAT) complex levels. Compared with the control group, patients on day 1 had significantly decreased (p < 0.001) antigenic protein C (69 +/- 28%) and protein C inhibitor (PCI) (33 +/- 22%) whereas a significant increase in the levels of activated protein C (APC) complexed with alpha 1-antitrypsin (alpha 1AT) (APC:alpha 1AT, 26 +/- 15 ng/mL) and APC:PCI complex (3.0 +/- 2.0 ng/mL), and in the level of plasma kallikrein (KK) complexes with PCI (KK:PCI) (31 +/- 22 ng/mL) was observed. There was a positive correlation between APC:alpha 1AT and TAT complex levels (r = 0.597, p = 0.009). In the follow-up a trend toward normal values in antigenic protein C and PCI, and in APC:PCI and KK:PCI complex levels was found. However, PCI remained significantly decreased compared to normal values. C4b-binding protein, alpha 1AT, and TAT and APC:alpha 1AT complexes did not show any significant variations during the course of the disease, suggesting the contribution of the inflammatory and haemostatic responses, in spite of the good recovery of the patients. This study shows that in the course of sepsis, patients experience a generalized activation of the protein C pathway which was more prominent on day 1, resulting in the consumption of protein C and PCI and in the increase of APC:inhibitor complexes. Moreover, these data provide further evidence that KK:PCI circulating complexes occur in vivo.
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PMID:Activation of the protein C pathway in acute sepsis. 749 7

This study evaluates the contact system, coagulation inhibitors and fibrinolysis in 23 full-term newborns with sepsis (8 with septic shock). The results were compared with a group of 20 healthy newborns. Blood samples were obtained at the time of clinical diagnosis and 3 days after the antibiotic therapy was started. The results showed that: severe infection was associated with activation of the contact system, depletion of anticoagulant proteins and elevation of C4b-binding protein levels. There was a shift in protein S to the complexed inactive form, and the thrombin-antithrombin complexes increased. These changes occurred in parallel to both activation and inhibition of fibrinolysis. These changes were more pronounced in the septic shock patients than in nonshock neonates. After therapy, this procoagulant state decreased among survivor patients while in those who died, the abnormalities in coagulation did not improve. Our study suggests that neonatal sepsis induces a hypercoagulable state that persists in nonsurvivor neonates despite a correct treatment.
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PMID:Coagulation, fibrinolytic and kallikrein systems in neonates with uncomplicated sepsis and septic shock. 827 17

Activation of the complement system was studied in baboons that were challenged with live Escherichia coli. In the group challenged with a lethal dose (n = 4), the complement activation parameters C3b/c, C4b/c, and C5b-9 increased 13, 5, and 12 times the baseline value, respectively, during the first 6 h after the E. coli infusion, whereas in the group challenged with a sublethal dose (n = 10), they increased only moderately, by 2 to 3 times the baseline value. However, in this latter group, a more pronounced activation occurred at 24 h. Subsequent experiments showed that this second phase in complement activation started at 6 h after the challenge, at which time infused microorganisms had been cleared from the circulation. The simultaneous increase in C-reactive protein with this second phase suggested an endogenous activation mechanism involving this acute-phase protein. Levels of inactivated (modified) C1 inhibitor also increased in both groups, with peak levels of 2.5 times the baseline value at 24 h in the sublethal group and of 4 times at 6 h after the challenge in the lethal group. Thus, activation of complement in this animal model for sepsis occurs in a biphasic pattern, the initial phase mediated by the bacteria and the later phase mediated by an endogenous mechanism possibly involving C-reactive protein. The differences in complement activation between animals with lethal or sublethal sepsis support the hypothesis that complement activation contributes to the lethal complications of sepsis.
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PMID:Activation of the complement system in baboons challenged with live Escherichia coli: correlation with mortality and evidence for a biphasic activation pattern. 840 18

In previous studies, we have shown that administration of monoclonal antibody (MoAb) C6B7 against human factor XII to baboons challenged with a lethal dose of Escherichia coli abrogates activation of the contact system and modulates secondary hypotension. To evaluate the contribution of activated contact proteases to the appearance of other inflammatory mediators in this experimental model of sepsis, we studied the effect of administration of MoAb C6B7 on activation of complement and fibrinolytic cascades, stimulation of neutrophil degranulation, and release of the proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Activation of the complement system, as reflected by circulating C3b/c and C4b/c levels, was significantly reduced in five animals that had received MoAb C6B7 before a lethal dose of E coli as compared with five control animals that had been given a lethal challenge only. Inhibition of contact activation also modulated the fibrinolytic response, since the release of tissue-type plasminogen activator (t-PA) and the appearance of plasmin-alpha2-antiplasmin (PAP) complexes into the circulation was significantly attenuated upon pretreatment with anti-factor XII MoAb. In contrast, plasma levels of plasminogen activator inhibitor (PAI) were modestly enhanced in the treatment group. Degranulation of neutrophils, as assessed by circulating elastase-alpha1-protease inhibitor complexes, and release of IL-6 but not of TNF-alpha was decreased in anti-factor XII-treated animals. Observed differences in the inflammatory response between treatment and control groups were not likely due to different challenges, since the number of E coli that had been infused, as well as circulating levels of endotoxin after the challenge, were similar for both groups. These data suggest that activation of the contact system modulates directly or indirectly various mediator systems involved in the inflammatory response during severe sepsis in nonhuman primates.
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PMID:Inhibition of factor XII in septic baboons attenuates the activation of complement and fibrinolytic systems and reduces the release of interleukin-6 and neutrophil elastase. 863 Mar 96

This review presents the rationale for and main results of coagulation inhibitor substitution during experimental and human sepsis. Activation of the contact system induces activation of the classical complement pathway with generation of anaphylatoxins, of the kinins pathway and of fibrinolysis. Physiologic inhibition depends on the C1-inhibitor (C1-Inh.). Septic patients exhibit a relative deficiency of biologically active C1-Inh. Substitution with concentrations of C1-Inh has been safely performed and preliminary results are consistent with a possible beneficial effect on hypotension and vasopressor requirement in septic shock. The extrinsic pathway is the main initial coagulation process involved in sepsis-induced DIC. Endothelial and monocyte generation of tissue factor (TF) is activated by bacterial products and endotoxin. Activation of TF is counteracted by a specific tissue factor pathway inhibitor (TFPI). The potential for TFPI substitution to inhibit the activation of the coagulation cascade in sepsis requires further study. Thrombin generation is inhibited by antithrombin III (AT III) and the protein C-protein S system. During sepsis, AT III is consumed and degraded by elastase. Animal studies have shown that DIC and death were prevented by high doses of AT III concentrates. Although a significant reduction in the duration of biological symptoms of DIC has been reported in most human studies, the usefulness of AT III substitution in human sepsis is still debated. None of the studies was able to document a statistically significant reduction in mortality. Protein C is activated by thrombomodulin and, with its cofactor protein S, inhibits factors Va and VIIIa. The free level of protein S depends on the level of the C4b binding protein (C4bBP), an acute-phase complement regulatory protein. During sepsis, protein C activity is significantly reduced, either by acute consumption or by thrombomodulin down-regulation, and increased levels of plasma C4bBP inhibit protein S. Infusion of activated protein C and protein S substitution both protect animals from the lethal effects of bacteria. Combining these different coagulation inhibitors should be carefully studied before its use in septic patients is recommended.
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PMID:Coagulation inhibitor substitution during sepsis. 863 34

We evaluated the effect of C1 inhibitor (C1-inh), an inhibitor of the classical pathway of complement and the contact system, on the physiologic and inflammatory response in baboons suffering from lethal Escherichia coli sepsis. Five animals pretreated with 500 U/kg C1-inh (treatment group; n = 5), followed by a 9-h continuous infusion of 200 U/kg C1-inh subsequent to bacterial challenge, were compared with five controls receiving E. coli alone. Of the treatment group, one animal survived and another lived beyond 48 h, whereas all control animals died within 27 h. In four of five treated animals, less severe pathology was observed in various target organs. C1-inh administration did not prevent the hemodynamic or hematologic changes observed upon E. coli infusion. The activation of fibrinolysis and the development of disseminated intravascular coagulation were essentially unaffected by C1-inh. However, C1-inh supplementation significantly reduced decreases in plasma levels of factor XII and prekallikrein and abrogated the systemic appearance of C4b/c, indicating substantial inhibition of activation of the contact system and the classical complement pathway, respectively. Furthermore, treated animals displayed a reduced elaboration of various cytokines including TNF, IL-10, IL-6, and IL-8. Thus, the administration of C1-inh may have a beneficial but modest effect on the clinical course and outcome of severe sepsis in nonhuman primates. We suggest that activated complement and/or contact system proteases may, at least in part, contribute to the attendant manifestations of septic shock through an augmentation of the cytokine response.
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PMID:Effect of C1 inhibitor on inflammatory and physiologic response patterns in primates suffering from lethal septic shock. 955 6

To assess the relationship between capillary leakage and inflammatory mediators during sepsis, blood samples were taken on hospital admission, as well as 24 and 72 h later, from 52 children (median age, 3.3 years) with severe meningococcal sepsis, of whom 38 survived and 14 died. Parameters related to cytokines (interleukin 6 [IL-6] IL-8, plasma phospholipase A2, and C-reactive protein [CRP]), to neutrophil degranulation (elastase and lactoferrin), to complement activation (C3a, C3b/c, C4b/c, and C3- and C4-CRP complexes), and to complement regulation (functional and inactivated C1 inhibitor and C4BP) were determined. The degree of capillary leakage was derived from the amount of plasma infused and the severity of disease by assessing the pediatric risk of mortality (PRISM) score. Levels of IL-6, IL-8, C3b/c, C3-CRP complexes, and C4BP on admission, adjusted for the duration of skin lesions, were significantly different in survivors and nonsurvivors (C3b/c levels were on average 2.2 times higher in nonsurvivors, and C3-CRP levels were 1.9 times higher in survivors). Mortality was independently related to the levels of C3b/c and C3-CRP complexes. In agreement with this, levels of complement activation products correlated well with the PRISM score or capillary leakage. Thus, these data show that complement activation in patients with severe meningococcal sepsis is associated with a poor outcome and a more severe disease course. Further studies should reveal whether complement activation may be a target for therapeutical intervention in this disease.
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PMID:Complement activation in relation to capillary leakage in children with septic shock and purpura. 978 43

Neisseria meningitidis (meningococcus) is an important cause of meningitis and sepsis. Currently, there is no effective vaccine against serogroup B meningococcal infection. Host defense against neisseriae requires the complement system (C) as indicated by the fact that individuals deficient in properdin or late C components (C6-9) have an increased susceptibility to recurrent neisserial infections. Because the classical pathway (CP) is required to initiate efficient complement activation on neisseriae, meningococci should be able to evade it to cause disease. To test this hypothesis, we studied the interactions of meningococci with the major CP inhibitor C4b-binding protein (C4bp). We tested C4bp binding to wild-type group B meningococcus strain (H44/76) and to 11 isogenic mutants thereof that differed in capsule expression, lipo-oligosaccharide sialylation, and/or expression of either porin (Por) A or PorB3. All strains expressing PorA bound radiolabeled C4bp, whereas the strains lacking PorA bound significantly less C4bp. Increased binding was observed under hypotonic conditions. Deleting PorB3 did not influence C4bp binding, but the presence of polysialic acid capsule reduced C4bp binding by 50%. Bound C4bp remained functionally active in that it promoted the inactivation of C4b by factor I. PorA-expressing strains were also more resistant to C lysis than PorA-negative strains in a serum bactericidal assay. Binding of C4bp thus helps Neisseria meningitidis to escape CP complement activation.
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PMID:Binding of the complement inhibitor C4bp to serogroup B Neisseria meningitidis. 1587 29

Mannose-binding lectin (MBL) is an innate immune system pattern recognition molecule that kills a wide range of pathogens via the lectin complement pathway. MBL deficiency is associated with severe infection but the best measure of this deficiency is undecided. We investigated the influence of MBL functional deficiency on the development of sepsis in 195 adult patients, 166 of whom had bloodstream infection and 35 had pneumonia. Results were compared with 236 blood donor controls. MBL function (C4b deposition) and levels were measured by enzyme-linked immunosorbent assay. Using receiver-operator characteristics of MBL function in healthy controls, we identified a level of <0.2 U microL(-1) as a highly discriminative marker of low MBL2 genotypes. Median MBL function was lower in sepsis patients (0.18 U microL(-1)) than in controls (0.48 U microL(-1), P<0.001). MBL functional deficiency was more common in sepsis patients than controls (P<0.001). MBL functional deficient patients had significantly higher sequential organ failure assessment (SOFA) scores and higher MBL function and levels were found in patients with SOFA scores predictive of good outcome. Deficiency of MBL function appears to be associated with bloodstream infection and the development of septic shock. High MBL levels may be protective against severe sepsis.
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PMID:Low mannose-binding lectin function is associated with sepsis in adult patients. 1706 81


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