Search

BIBT986 is a dual inhibitor of factors Xa and IIa. The aim of this study was to compare with placebo the effect of three doses of BIBT986 on coagulation, platelet activation, and inflammation. This was a prospective, randomized, double-blind, placebo-controlled, parallel-group dose escalation trial in 48 healthy male volunteers. Participants received one of three doses of BIBT986 or placebo intravenously together with a bolus infusion of 2 ng/kg lipopolysaccharide (LPS). BIBT986 dose-dependently changed global coagulation parameters and in vivo markers of thrombin generation and action: BIBT986 doses, which prolonged activated partial thromboplastin time by 100%, completely suppressed the LPS-induced increases in prothrombin fragment, thrombin-antithrombin complexes, and D-dimer, which were 6.1-, 14.5, and 3.5-fold in the placebo group, respectively. BIBT986 did not influence inflammation, fibrinolysis, or platelet activation. Therefore, BIBT986 is a potent anticoagulant in the human endotoxemia model.

Background: Thrombelastography (TEG) is a whole blood assay to evaluate the viscoelastic properties during blood clot formation and clot lysis. Rotation thrombelastography (e.g. ROTEM) has overcome some of the limitations of classical TEG and is used as a point-of-care device in several clinical settings of coagulation disorders. Endotoxemia leads to systemic activation of the coagulation system and fibrinolysis in humans., Objectives: We validated whether ROTEM is sensitive to endotoxin induced, tissue factor-triggered coagulation and fibrinolysis and if its measures correlate with biohumoral markers of coagulation and fibrinolysis., Patients and Methods: Twenty healthy male volunteers participated in this randomized placebo-controlled trial. Volunteers received either 2 ng kg(-1) National Reference Endotoxin or saline., Results: Endotoxemia significantly shortened ROTEM clotting time (CT) by 36% (CI 0.26-0.46; P < 0.05) with a strong inverse correlation with the peak plasma levels of prothrombin fragments (F(1 + 2)) (r = -0.83, P < 0.05). Additionally, endotoxin infusion enhanced maximal lysis (ML) 3.9-fold (CI: 2.5-5.2) compared with placebo or baseline after 2 h (P < 0.05). Peak ML and peak tissue plasminogen activator (t-PA) values correlated excellently (r = 0.82, P < 0.05). ROTEM parameters clot formation time and maximal clot firmness were not affected by LPS infusion, whereas platelet function analyzer (PFA-100) closure times decreased., Conclusions: Rotation thrombelastography (ROTEM) detects systemic changes of in vivo coagulation activation, and importantly it is a point of care device, which is sensitive to changes in fibrinolysis in humans. The ex vivo measures CT and ML correlate very well with established in vivo markers of coagulation activation (F(1 + 2)) and fibrinolysis (t-PA), respectively.

Re(x)W(1-x)O3.H2O and Re(x)W(1-x)O3 phases are prepared by a new organometallic chimie douce concept employing the organometallic precursor methyltrioxorhenium.

Background: Interleukin 6 (IL-6) is a pleiotropic cytokine that plays an essential role in the pathogenesis of acute and chronic infections. As the role of the IL-6 G(-174)C polymorphism in determining serum concentrations of IL-6 is controversial, we studied the genotype-specific IL-6 response in a well-standardized model of systemic inflammation., Methods: A total of 76 healthy young males (age range, 19-35 years) received a single bolus of 2 ng/kg endotoxin [lipopolysaccharide (LPS)] intravenously. Plasma IL-6 was measured by enzyme immunoassay at 0, 2, 6, and 24 h after LPS infusion, and the IL-6 promoter genotype was analyzed by a mutagenic separated PCR assay., Results: IL-6 increased 300-fold 2 h after LPS challenge and returned almost to normal within 24 h. Neither basal IL-6 nor the IL-6 response to LPS was significantly affected by the IL-6 promoter genotype., Conclusions: The IL-6 G(-174)C promoter polymorphism does not significantly influence basal concentrations of IL-6 or peak IL-6 in human endotoxemia.

P-selectin glycoprotein ligand-1 (PSGL-1, CD162), the counter-receptor for P-selectin and possibly E- and L-selectin, mediates rolling of leukocytes during inflammation and, thus, plays a pivotal role in hemostasis and inflammation. PSGL-1 is constitutively expressed on circulating leukocytes. Until recently, PSGL-1 has been considered not to be regulated upon cell activation. As modulation of PSGL-1 has only recently been reported for three proinflammatory substances, PSGL-1 regulation was examined during systemic inflammation in humans. Nine healthy human volunteers received a bolus of 2 ng/kg LPS i.v. Endotoxin infusion down-modulated PSGL-1 expression on neutrophils, with a maximum at 6-8 hr (-22%; P =0.001 vs. baseline and placebo), which correlated with peak neutrophilia. Similar PSGL-1 down-regulation was observed on monocytes. sPSGL-1 plasma levels increased trendwise after LPS infusion (+12% at 6 hr; P =0.10). In vitro LPS stimulation of whole blood significantly down-regulated PSGL-1 on neutrophils (-43%) and monocytes (-35%) as early as 2 hr ( P <0.05; n =5) in both EDTA and lepirudin anticoagulated samples. In summary, PSGL-1 is down-modulated on neutrophils and monocytes during endotoxemia in humans. PSGL-1 down-regulation could potentially facilitate the development of neutrophilia.

Whereas bleeding is the most frequent adverse event encountered in patients receiving glycoprotein (GP) IIb/IIIa inhibitors, there are currently no recommendations for how to treat such patients. The present study tested the hypothesis that infusion of desmopressin (DDAVP) reverses the in vitro platelet dysfunction induced by GPIIb/IIIa inhibitors (+l-aspirin). Study group 1 (10 healthy volunteers) received a DDAVP infusion to establish dose-response curves for the in vitro inhibition of platelet function by eptifibatide, abciximab, and tirofiban together with l-aspirin before and after DDAVP. In a randomized, double-blind, placebo-controlled, crossover study (group 2) volunteers received l-aspirin and a standard eptifibatide infusion. Thereafter, DDAVP or a physiologic saline infusion was given over 30 minutes. In group 1, all GPIIb/IIIa inhibitors prolonged collagen-epinephrine (CEPI) and collagen-adenosine diphosphate (CADP) closure times (CTs), measured with the platelet function analyzer 100 (PFA-100). DDAVP caused a shift in the concentration response curves to the right of all 3 GPIIb/IIIa inhibitors. In group 2, DDAVP accelerated the normalization of CADP-CT and CEPI-CT after the stop of eptifibatide infusion with a maximum effect at 1.5 hours to 2 hours. In contrast, CEPI-CT remained above normal in the placebo group for more than 4 hours. In conclusion, DDAVP accelerates normalization of the in vitro platelet dysfunction induced by GPIIb/IIIa inhibitors (+l-aspirin).

A potential role of Fas/FasL in sepsis is suggested by recent clinical studies showing that Fas and FasL could serve as markers for severity of sepsis. We sought to determine the effect of endotoxin infusion on expression of Fas and FasL. Healthy volunteers (n = 30) received 2 ng/kg endotoxin i.v. Endotoxin infusion decreased Fas expression on neutrophils and monocytes by 15-20% at 2-4 h in vivo and also in vitro. A rebound increase in Fas (30%) was seen on neutrophils at 24 h, and soluble FasL levels increased by 100% at 24 h. Fas mRNA levels increased 6-fold 4-6 h after endotoxin infusion as measured by real-time polymerase chain reaction. In contrast, FasL-mRNA levels in circulating leukocytes decreased by >80% 2h after lipopolysaccharide infusion. In summary, low-grade endotoxemia induces early down-modulation of Fas on leukocytes, followed by a several-fold increase in Fas-mRNA expression leading to later Fas surface upregulation on neutrophils. The upregulation of Fas expression, Fas mRNA, and later in FasL and sFas levels in endotoxemia replicates the increased fas levels found in septic patients.

Thrombin is a coagulation protease that activates platelets, endothelial cells, leukocytes and mesenchymal cells. Thrombin signaling is mediated at least in part by protease-activated receptors (PARs). As little is known about the in vivo regulation of PAR1, this study aimed to characterize the effects of systemic thrombin formation during human endotoxemia on the regulation of PAR1 and the associated responsiveness of human platelets to thrombin receptor activating peptide (TRAP). Endotoxin (2 ng/kg) was infused into 40 healthy men to study the regulation of PAR1 in systemic human inflammation. The SPAN12 antibody was used to determine the in vivo regulation of PAR1. To measure whether modulation of the PAR1 receptor may be associated with altered platelet reactivity, whole blood was stimulated with TRAP ex vivo. Thrombin generation was determined by prothrombin (F(1+2)) fragment. F(1+2) levels increased almost 9-fold from 0.5+/-0.1 nmol/L to 4.5+/-1.9 nmol/L at 4 h (p<0.001). PAR1 decreased by approximately 8% (p<0.001) within 2 h after endotoxin infusion and stayed at those levels until 6 h. Concomitantly, TRAP induced P-selectin expression maximally decreased by 18% (p<0.001) at 6 h. In conclusion, PAR1 expression is down-regulated on platelets during systemic thrombin formation induced by inflammation in humans which results in decreased responsiveness to subsequent stimulation of the PAR1 receptor.

The modulation of Toll-like receptors (TLR) 1, 2 and 4 was studied during experimental human endotoxaemia. Healthy volunteers received 2 ng/kg of lipopolysaccharide (LPS) endotoxin (n = 10). TLR1, 2 and 4 expression occurred on monocytes and neutrophils, with monocytes expressing higher baseline levels of TLR2. LPS infusion downmodulated TLR4 expression on neutrophils, with maximal downregulation occurring at 24 h (-62% from baseline; P < 0.03 versus baseline). Monocyte TLRs were upregulated in vivo (TLR1 and 2), and in vitro (TLR1, 2 and 4) 8 h after LPS bolus (P < 0.05 versus baseline). Therefore, neutrophils and monocytes differentially express surface TLRs, and endotoxaemia differentially regulates TLR expression.

Background: Inhibition of the tissue factor-factor VIIa pathway attenuated the activation of coagulation and prevented death in a gram-negative bacteremia primate model of sepsis. This lethal animal model suggested that tissue factor also influences inflammatory cascades., Methods: This trial examined the pharmacodynamic effects of active site-inhibited factor VIIa (FFR-recombinant factor VIIa [rFVIIa]; ASIS) on endotoxin-induced procoagulant, fibrinolytic, and inflammatory responses in healthy humans. A double-blind, randomized, placebo-controlled, parallel-group study was conducted in 12 healthy male volunteers. Subjects received a bolus infusion of 2-ng/kg endotoxin, followed by a bolus infusion of ASIS (400 microg/kg) or placebo 10 minutes later., Results: Endotoxin injection induced inflammation, activation of coagulation, and activation and subsequent inhibition of fibrinolysis. ASIS infusion completely blocked thrombin and fibrin generation, as measured by plasma levels of prothrombin fragment (no increase in the ASIS group, as compared with a 13-fold increase in the placebo group at 4 hours; P <.01), soluble fibrin, and fibrin split product D-dimer. ASIS did not alter endotoxin-induced changes in the fibrinolytic system, cytokine levels, or markers of endothelial (E-selectin, thrombomodulin) or platelet (P-selectin) activation., Conclusions: In summary, ASIS effectively and selectively attenuates tissue factor-induced thrombin generation. Because ASIS was well tolerated, this study provides seminal data to further characterize its anticoagulant and putative anti-inflammatory effects in critically ill patients.