Untargeted Metabolomics Differentiates l-Carnitine Treated Septic Shock 1-Year Survivors and Nonsurvivors.

l-Carnitine is a candidate therapeutic for the treatment of septic shock, a condition that carries a ≥40% mortality. Responsiveness to l-carnitine may hinge on unique metabolic profiles that are not evident from the clinical phenotype. To define these profiles, we performed an untargeted metabolomic analysis of serum from 21 male sepsis patients enrolled in a placebo-controlled l-carnitine clinical trial. Although treatment with l-carnitine is known to induce changes in the sepsis metabolome, we found a distinct set of metabolites that differentiated 1-year survivors from nonsurvivors. Following feature alignment, we employed a new and innovative data reduction strategy followed by false discovery correction, and identified 63 metabolites that differentiated carnitine-treated 1-year survivors versus nonsurvivors. Following identification by MS/MS and database search, several metabolite markers of vascular inflammation were determined to be prominently elevated in the carnitine-treated nonsurvivor cohort, including fibrinopeptide A, allysine, and histamine. While preliminary, these results corroborate that metabolic profiles may be useful to differentiate l-carnitine treatment responsiveness. Furthermore, these data show that the metabolic signature of l-carnitine-treated nonsurvivors is associated with a severity of illness (e.g., vascular inflammation) that is not routinely clinically detected.

Fibrinopeptide A induces C-reactive protein expression through the ROS-ERK1/2/p38-NF-κB signal pathway in the human umbilical vascular endothelial cells.

Atherosclerosis is a chronic inflammatory disease of the arterial wall. Inflammation causes endothelial injury and dysfunction, which is an initial step of atherosclerosis. Fibrinopeptide A (FPA) is a biomarker of the activation of the coagulation system, and a high concentration of FPA in the blood occurs in patients with ischemic cardiocerebrovascular diseases. The present research observed that FPA stimulated the generation of C-reactive protein (CRP), IL-1ß, and IL-6 in human umbilical vascular endothelial cells (HUVECs); and anti-IL-1 ß and anti-IL-6 neutralizing antibodies did not alter FPA-induced CRP expression in HUVECs. The subchronic administration of FPA into rats increased the plasma FPA and CRP levels. Further studies showed that FPA stimulated superoxide anion generation, activated ERK1/2 and p38, promoted nuclear factor κB (NF-κB) nuclear translocation, and raised the NF-κB level in the nuclei of HUVECs. Antioxidant N-acetylcysteine (NAC), complex II inhibitor thenoyltrifluoroacetone (TTFA), and NADPH oxidase inhibitor diphenyleneiodonium (DPI) inhibited FPA-stimulated generation of superoxide anion, and NAC reduced FPA-induced expressions of the phosphorylated ERK1/2 and p38. NAC, TTFA, DPI, inhibitors of ERK1/2, p38, and NF-κB all downregulated FPA-induced CRP expression. These results indicate that FPA induces CRP expression in HUVECs via the ROS-ERK1/2/p38-NF-κB signal pathway. Moreover, this is the first report that FPA produces a proinflammatory effect on the vascular endothelial cells.

[The clotting tests and molecular markers in evaluating of coagulation alterations against the background of anti-thrombotic prevention by Dabigatran after large orthopedic operations].

The large orthopedic operations are associated with high risk of development of thrombosis of deep veins of lower extremities. Nowadays, new oral anticoagulants are widely applied for anti-thrombotic prevention. The coagulation alterations against the background of effect of Dabigatran, a direct inhibitor of thrombin were examined in 30 patients underwent endoprosthesis replacement of knee joint. The routine clotting indices, fibrinopeptid A, soluble fibrin-monomeric complexes, D-dimer. The samples of blood were selected before operation, after 30 minutes, and at 1st, 3d, 7th and 14th day after endoprosthesis replacement of knee joint. It is demonstrated that routine clotting tests and also detection of D-dimer and soluble fibrin-monomeric complexes provide no adequate evaluation of coagulation activity in patients underwent large orthopedic operation. The concentration of specific marker of fibrin formation of fibrinopeptid A continues to be increased no less than two weeks after endoprosthesis replacement of knee joint that testifies keeping hyper-coagulation and risk of thrombosis. The intake of Dabigatran etexilate in fixed dosage does not exclude development of thrombosis of deep veins of lower extremities that substantiates point of view concerning usefulness of individualization of anti-thrombotic prevention in case of application of new oral anti-coagulants.

Expression of a new serine protease from Crotalus durissus collilineatus venom in Pichia pastoris and functional comparison with the native enzyme.

Snake venom serine proteases (SVSPs) act primarily on plasma proteins related to blood clotting and are considered promising for the treatment of several hemostatic disorders. We report the heterologous expression of a serine protease from Crotalus durissus collilineatus, named collinein-1, in Pichia pastoris, as well as the enzymatic comparative characterization of the toxin in native and recombinant forms. The complementary DNA (cDNA) encoding collinein-1 was amplified from cDNA library of C. d. collilineatus venom gland and cloned into the pPICZαA vector. The recombinant plasmid was used to transform cells of KM71H P. pastoris. Heterologous expression was induced by methanol and yielded 56 mg of recombinant collinein-1 (rCollinein-1) per liter of culture. The native collinein-1 was purified from C. d. collilineatus venom, and its identity was confirmed by amino acid sequencing. The native and recombinant enzymes showed similar effects upon bovine fibrinogen by releasing preferentially fibrinopeptide A. Although both enzymes have induced plasma coagulation, native Colinein-1 has shown higher coagulant activity. The serine proteases were able to hydrolyze the chromogenic substrates S-2222, S-2238, and S2302. Both enzymes showed high stability on different pH and temperature, and their esterase activities were inhibited in the presence of Zn2+ and Cu2+. The serine proteases showed similar k cat/K m values in enzyme kinetics assays, suggesting no significant differences in efficiency of these proteins to hydrolyze the substrate. These results demonstrated that rCollinein-1 was expressed with functional integrity on the evaluated parameters. The success in producing a functionally active recombinant SVSP may generate perspectives to their future therapeutic applications.

Batroxobin binds fibrin with higher affinity and promotes clot expansion to a greater extent than thrombin.

Batroxobin is a thrombin-like serine protease from the venom of Bothrops atrox moojeni that clots fibrinogen. In contrast to thrombin, which releases fibrinopeptide A and B from the NH2-terminal domains of the Aα- and Bß-chains of fibrinogen, respectively, batroxobin only releases fibrinopeptide A. Because the mechanism responsible for these differences is unknown, we compared the interactions of batroxobin and thrombin with the predominant γA/γA isoform of fibrin(ogen) and the γA/γ' variant with an extended γ-chain. Thrombin binds to the γ'-chain and forms a higher affinity interaction with γA/γ'-fibrin(ogen) than γA/γA-fibrin(ogen). In contrast, batroxobin binds both fibrin(ogen) isoforms with similar high affinity (Kd values of about 0.5 µM) even though it does not interact with the γ'-chain. The batroxobin-binding sites on fibrin(ogen) only partially overlap with those of thrombin because thrombin attenuates, but does not abrogate, the interaction of γA/γA-fibrinogen with batroxobin. Furthermore, although both thrombin and batroxobin bind to the central E-region of fibrinogen with a Kd value of 2-5 µM, the α(17-51) and Bß(1-42) regions bind thrombin but not batroxobin. Once bound to fibrin, the capacity of batroxobin to promote fibrin accretion is 18-fold greater than that of thrombin, a finding that may explain the microvascular thrombosis that complicates envenomation by B. atrox moojeni. Therefore, batroxobin binds fibrin(ogen) in a manner distinct from thrombin, which may contribute to its higher affinity interaction, selective fibrinopeptide A release, and prothrombotic properties.

Relevance of fibrinolytic protein (D-dimer) and fibrinopeptide A as markers of sickle cell anaemia vaso-occlusive crisis.

AIMS AND OBJECTIVES: To determine the plasma concentration of fibrinolytic protein (D-dimer) and Fibrinopeptide A(FPA) in sickle cell anaemia (SCA) patients in steady state and vaso-occlusive crisis(VOC) for the purpose of determining their clinical value in assessing/or predicting the onset of VOC Subjects and Methods: A total of 25 (14 Males: 11Females) HbSS subjects in VOC , 24 (13M:11F) HbSS subjects in steady state between the ages of 10-40 years old and 30 (17M:13F) healthy HbAA volunteers, of the same age and sex with the subjects were recruited for the study. Haematological parameters{Haemoglobin (Hb), Haematocrit(HCT), White blood cell count(WBC) and Platelets(Plt)}, prothrombin time(PT), activated partial thromboplastin time(APTT), plasma concentrations of D-dimer and FPA were determined. RESULTS: Haemoglobin concentration of 6.22±1.75 g/dl and HCT of 18.45±6.43% for SCA subjects in VOC; Hb of 7.42±1.36 g/dl and HCT of 22.83 ±4.68% in steady state were significantly decreased(p <0.01) compared with Hb(13.0±1.04 g/dl and HCT( 41.09±3.50%) for HbAA controls. However, plasma FPA of 680.99 ± 411.37 ng/ml, WBC of 19.44±14.88 x109/L, Plt of 292.72±148.57 x109/L, APTT of 52.24±5.34sec. for SCA subjects in VOC and Plasma FPA of 449.67 ± 310.01 ng/ml, WBC of 11.84±7.67 x109/L, Plt of 292.72±148.57 x109/L, APTT of 47.76±4.80secs in steady state were significantly increased when compared with FPA(163.52 ± 86.26ng/ml), WBC(5.15±1.24 x109/L), Plt(173.44±59.90 x109/ L), APTT( 37.75±1.41secs) for HbAA controls. CONCLUSION: Fibrinolysis is not significantly increased in SCA either in the steady state or during VOC. Fibrinopeptide A assay appears to be of value in the assessment of VOC in sickle cell anaemia.

Visualization and identification of the structures formed during early stages of fibrin polymerization.

We determined the sequence of events and identified and quantitatively characterized the mobility of moving structures present during the early stages of fibrin-clot formation from the beginning of polymerization to the gel point. Three complementary techniques were used in parallel: spinning-disk confocal microscopy, transmission electron microscopy, and turbidity measurements. At the beginning of polymerization the major structures were monomers, whereas at the middle of the lag period there were monomers, oligomers, protofibrils (defined as structures that consisted of more than 8 monomers), and fibers. At the end of the lag period, there were primarily monomers and fibers, giving way to mainly fibers at the gel point. Diffusion rates were calculated from 2 different results, one based on sizes and another on the velocity of the observed structures, with similar results in the range of 3.8-0.1 µm²/s. At the gel point, the diffusion coefficients corresponded to very large, slow-moving structures and individual protofibrils. The smallest moving structures visible by confocal microscopy during fibrin polymerization were identified as protofibrils with a length of approximately 0.5 µm. The sequence of early events of clotting and the structures present are important for understanding hemostasis and thrombosis.

Fibrinopeptides A and B release in the process of surface fibrin formation.

Fibrinogen adsorption on a surface results in the modification of its functional characteristics. Our previous studies revealed that fibrinogen adsorbs onto surfaces essentially in 2 different orientations depending on its concentration in the solution: "side-on" at low concentrations and "end-on" at high concentrations. In the present study, we analyzed the thrombin-mediated release of fibrinopeptides A and B (FpA and FpB) from fibrinogen adsorbed in these orientations, as well as from surface-bound fibrinogen-fibrin complexes prepared by converting fibrinogen adsorbed in either orientation into fibrin and subsequently adding fibrinogen. The release of fibrinopeptides from surface-adsorbed fibrinogen and from surface-bound fibrinogen-fibrin complexes differed significantly compared with that from fibrinogen in solution. The release of FpB occurred without the delay (lag phase) characteristic of its release from fibrinogen in solution. The amount of FpB released from end-on adsorbed fibrinogen and from adsorbed fibrinogen-fibrin complexes was much higher than that of FpA. FpB is known as a potent chemoattractant, so its preferential release suggests a physiological purpose in the attraction of cells to the site of injury. The N-terminal portions of fibrin ß chains including residues Bß15-42, which are exposed after cleavage of FpB, have been implicated in many processes, including angiogenesis and inflammation.

Fibrinogen Sumperk II: dysfibrinogenemia in an individual with two coding mutations.

Fibrinogen­a 340-kDa glycoprotein­plays a crucial role in blood coagulation, platelet aggregation, wound healing, and other physiological processes. A mutation in fibrinogen may lead to congenital dysfibrinogenemia,a rare disease characterized by the functional deficiency of fibrinogen. About 580 cases of abnormal fibrinogens have been reported worldwide; thereof 335 cases in the fibrinogen Aa chain[1]. To our knowledge, only five cases of abnormal fibrinogens with two mutations [2­6] and one case of two different mutations in the same family [7] have been described earlier. A 52-year-old female was examined for bleeding. Routine hemostasis screening resulted in a diagnosis of dysfibrinogenemia. Functional testing revealed prolonged fibrin polymerization, prolonged lysis of the clot, abnormal fibrin morphology,and fibrinopeptides release. Genetic analysis showed two heterozygous nonsense mutations­previously described mutation AaGly13Glu and a novel mutation Aa Ser314Cys. The mutation Aa Gly13-Glu was found in her brother and niece, but there was no evidence in either of the mutation Aa Ser314Cys. While mutation Aa Gly13Glu is responsible for abnormal fibrinopeptide release and prolonged thrombin time, the novel mutation Aa Ser314Cys seems to affect fibrin morphology and fibrinolysis.

Thrombogenicity of a new injectable biocompatible elastomer for aneurysm exclusion, compared to expanded polytetrafluoroethylene in a human ex vivo model.

OBJECTIVES: Customized aortic repair (CAR) is a new concept for endovascular aortic aneurysm repair in which a non-polymerised elastomer is injected to fill the aneurysm sac around a balloon catheter. Amongst other variables, the thrombogenicity of the elastomer should be tested, before further clinical experiments can take place. The aim of this human ex vivo study was to measure the thrombogenicity of the elastomer and to compare it to expanded polytetrafluoroethylene (ePTFE). DESIGN AND MATERIALS: In a validated ex vivo model, non-anticoagulated blood was drawn from the antecubital veins of 10 healthy donors with a 19-gauge needle. It was drawn through elastomer tubes and through ePTFE Gore-Tex vascular grafts, both 60 cm long and with an inner diameter of 3 mm. METHODS: Fibrinopeptide A (FPA) and P-selectin expression was measured in blood samples, collected at the end of the grafts. After the experiments, the deposition of platelets and fibrin onto the grafts was visualised by scanning electron microscopy. RESULTS: For these graft types, a progressive increase in FPA production was observed in time. No significant difference was observed between the elastomer and ePTFE grafts (p > 0.05). No increase in P-selectin expression, and thereby no platelet activation, was observed in the perfusate of either grafts (p > 0.05). By scanning electron microscopy, numerous platelet aggregates were observed on the ePTFE grafts, whereas just a few adhered platelets and no aggregates were observed in the elastomer grafts. CONCLUSIONS: The elastomer in its current formulation has a low thrombogenicity, comparable to ePTFE, making it an ideal substance for endovascular aneurysm sac filling. Further research should clarify the feasibility of CAR in vivo.

[Functional analysis for dysfibrinogenemias, Toyama and Adachi, which have a mutation of Aalpha16Arg-->His (CGT-->CAT) with aberrant fibrinopeptide A release].

We found and identified four heterozygous dysfibrinogenemias with AalphaR16H(CGT-->CAT) mutation in two families by coagulation tests and direct sequence analysis for PCR-amplified DNA fragments. Two dysfibrinogens were designated as fibrinogen Toyama and Adachi, according to the place of residence of proposituses, respectively. Patients' fibrinogen purified from plasma using immunoaffinity-chromatography was subjected to thrombin- or batroxobin-catalyzed fibrin polymerization, fibrinopeptide A (FPA) release, and clottability test. AalphaR16H-fibrinogen showed impaired thrombin or batroxobin-catalyzed fibrin polymerization in comparison with normal control fibrinogen. It is interesting that the period of protofibril formation of Toyama propositus was longest in those of four affected people. The clottability of AalphaR16H-fibrinogen was 66-70% with thrombin and higher than with batroxobin, 35-50%. In the same condition with fibrin polymerization, thrombin and batroxobin did not cleave the Aalpha16H-17G peptide-bonding, resulting in no release of variant FPA. From these results, we speculated that elongation of the two-stranded protofibril formation would be terminated by participation of the heterodimer fibrinogen molecules composed with a normal and an aberrant Aalpha-chain, and it would result in a decrease in fibrin polymerization. We speculated that the difference in the extent of impairment of fibrin polymerization among the patients might be caused by the different amount of heterodimers. Moreover, we also speculated that batroxobin-induced clottability was lower than thrombin-induced clottability, because batroxobin cannot induce the so-called "B-knob-b-hole" interaction, which enhances fibrin formation.

Novel aspects of fibrin(ogen) fragments during inflammation.

Coagulation is fundamental for the confinement of infection and/or the inflammatory response to a limited area. Under pathological inflammatory conditions such as arthritis, multiple sclerosis or sepsis, an uncontrolled activation of the coagulation system contributes to inflammation, microvascular failure and organ dysfunction. Coagulation is initiated by the activation of thrombin, which, in turn, triggers fibrin formation by the release of fibrinopeptides. Fibrin is cleaved by plasmin, resulting in clot lysis and an accompanied generation of fibrin fragments such as D and E fragments. Various coagulation factors, including fibrinogen and/or fibrin [fibrin(ogen)] and also fibrin degradation products, modulate the inflammatory response by affecting leukocyte migration and cytokine production. Fibrin fragments are mostly proinflammatory, however, Bß15-42 in particular possesses potential antiinflammatory effects. Bß15-42 inhibits Rho-kinase activation by dissociating Fyn from Rho and, hence prevents stress-induced loss of endothelial barrier function and also leukocyte migration. This article summarizes the state-of-the-art in inflammatory modulation by fibrin(ogen) and fibrin fragments. However, further research is required to gain better understanding of the entire role fibrin fragments play during inflammation and, possibly, disease development.

A novel variant fibrinogen, AαE11del, demonstrating the importance of AαE11 residue in thrombin binding.

INTRODUCTION: We identified a novel heterozygous AαE11del variant in a patient with congenital dysfibrinogenemia. This mutation is located in fibrinopeptide A (FpA). We analyzed the effect of AαE11del on the catalyzation of thrombin and batroxobin and simulated the stability of the complex structure between the FpA fragment (AαG6-V20) peptide and thrombin. MATERIALS AND METHODS: We performed fibrin polymerization and examined the kinetics of FpA release catalyzed by thrombin and batroxobin using purified plasma fibrinogen. To clarify the association between the AαE11 residue and thrombin, we calculated binding free energy using molecular dynamics simulation trajectories. RESULTS: Increasing the thrombin concentration improved release of FpA from the patient's fibrinogen to approximately 90%, compared to the previous 50% of that of normal fibrinogen. Fibrin polymerization of variant fibrinogen also improved. In addition, greater impairment of variant FpA release from the patient's fibrinogen was observed with thrombin than with batroxobin. Moreover, the calculated binding free energy showed that the FpA fragment-thrombin complex became unstable due to the missing AαE11 residue. CONCLUSIONS: Our findings indicate that the AαE11 residue is involved in FpA release in thrombin catalyzation more than in batroxobin catalyzation, and that the AαE11 residue stabilizes FpA fragment-thrombin complex formation.

Association Between Hemostatic Profile and Migraine: A Mendelian Randomization Analysis.

OBJECTIVE: To assess support for a causal relationship between hemostatic measures and migraine susceptibility using genetic instrumental analysis. METHODS: Two-sample Mendelian randomization instrumental analyses leveraging available genome-wide association study (GWAS) summary statistics were applied to hemostatic measures as potentially causal for migraine and its subtypes, migraine with aura (MA) and migraine without aura (MO). Twelve blood-based measures of hemostasis were examined, including plasma level or activity of 8 hemostatic factors and 2 fibrinopeptides together with 2 hemostasis clinical tests. RESULTS: There were significant instrumental effects between increased coagulation factor VIII activity (FVIII; odds ratio [95% confidence interval] 1.05 [1.03, 1.08]/SD, p = 6.08 × 10-05), von Willebrand factor level (vWF; 1.05 [1.03, 1.08]/SD, p = 2.25 × 10-06), and phosphorylated fibrinopeptide A level (1.13 [1.07, 1.19]/SD, p = 5.44 × 10-06) with migraine susceptibility. When extended to migraine subtypes, FVIII, vWF, and phosphorylated fibrinopeptide A showed slightly stronger effects with MA than overall migraine. Fibrinogen level was inversely linked with MA (0.76 [0.64, 0.91]/SD, p = 2.32 × 10-03) but not overall migraine. None of the hemostatic factors was linked with MO. In sensitivity analysis, effects for fibrinogen and phosphorylated fibrinopeptide A were robust, whereas independent effects of FVIII and vWF could not be distinguished, and FVIII associations were potentially affected by pleiotropy at the ABO locus. Causal effects from migraine to the hemostatic measures were not supported in reverse Mendelian randomization. However, MA was not included due to lack of instruments. CONCLUSIONS: The findings support potential causality of increased FVIII, vWF, and phosphorylated fibrinopeptide A and decreased fibrinogen in migraine susceptibility, especially for MA, potentially revealing etiologic relationships between hemostasis and migraine.

Discrimination of isobaric leucine and isoleucine residues and analysis of post-translational modifications in peptides by MALDI in-source decay mass spectrometry combined with collisional cooling.

Collisional cooling employed in an orthogonal time-of-flight mass spectrometer (o-TOF MS) stabilizes fragment ions that are generated by matrix-assisted laser desorption ionization in-source decay (MALDI ISD). By variation of the buffer gas pressure, ISD and "post-source decay" (PSD) dissociation channels can be switched on and off to some extent. Under high-pressure conditions, ISD type fragments of post-translationally modified (PTM) peptides are generated that contain even labile bound side groups; the examples of a phosphorylated and an O-glycosylated peptide are shown. At elevated laser fluences, d- and w-type fragment ions of peptides are detected as a result of high-energy side chain cleavage. This allows for differentiation of the isobaric amino acid residues leucine and isoleucine. Reduction of the cooling efficiency by lowering the buffer gas pressure results in the loss of the d-/w-type species, presumably in secondary metastable dissociation processes. This also enhances cleavage of the side groups from the PTM peptides and can be used to corroborate identification of the modification site. Furthermore, these measuring conditions generate small amounts of fragments containing sequence information about the cyclic part of a disulfide peptide by inducing symmetric and asymmetric cleavage of the intramolecular S-S bond.

[Dysfunction of coagulation processes in patients after acute coronary syndrome--therapeutic implications]. / Zaburzenia procesów krzepniecia u chorych po ostrym zespole wiencowym--implikacje terapeutyczne.

In the guidelines for patients with acute coronary syndrome (ACS), reperfusion, antiplatelet treatment, completed with parenteral anticoagulant are the standard therapy. It is because ACS is the result of occlusion of related artery by thrombus compound mostly of platelets, with processes of aggregation and adhesion in its pathogenesis. However, many patients after ACS experience major adverse cardiovascular events (MACE) despite optimal long term antiplatelet therapy. The possible reasons seem to be not only the resistance to this drugs but also underestimated coagulation processes. This review describes the dysfunction of particular coagulation parameters in patients with coronary artery disease and their relationship with MACE after ACS.

The action of MBL-associated serine protease 1 (MASP1) on factor XIII and fibrinogen.

The complement system is an important recognition and effector mechanism of the innate immune system that upon activation leads to the elimination of foreign bodies. It can be activated through three pathways of which the lectin pathway is one. The lectin pathway relies on the binding of mannan-binding lectin (MBL) or the ficolins and the subsequent activation of the MBL-associated serine proteases (MASPs), namely, MASP1, 2 and 3 which all form complexes with both MBL and the ficolins. Major substrates have only been identified for MASP2 i.e. C4 and C2. For MASP1 only a few protein substrates which are cleaved at a low rate have been identified while none are known for MASP3. Since chromogenic substrate screenings have shown that MASP1 has thrombin-like activity, we wanted to investigate the catalytic potential of MASP1 towards two major proteins involved in the clotting process, fibrinogen and factor XIII, and compare the activity directly with that of thrombin. We found that rMASP1 and thrombin cleave factor XIII A-chain and the fibrinogen beta-chain at identical sites, but differ in cleavage of the fibrinogen alpha-chain. The thrombin turnover rate of factor XIII is approximately 650 times faster than that of rMASP1 at 37 degrees C, pH 7.4. rMASP1 cleavage of fibrinogen leads to the release of the proinflammatory peptide fibrinopeptide B. Thus rMASP1 has similar, but not identical specificity to thrombin and its catalytic activity for factor XIII and fibrinogen cleavage is much lower than that of thrombin. Nevertheless, rMASP1 can drive the formation of cross-linked fibrinogen. Since MASP1 is activated on contact of MBL or the ficolins with microorganisms, fibrinogen and factor XIII may be involved in the elimination of invading pathogens.

Fibrinopeptide B and aggregation of fibrinogen.

Removal of fibrinopeptide B from human fibrinogen by reaction with the procoagulant enzyme from copperhead snake venom below 25 degrees C resulted in tight aggregation of the fibrinogen, which, in turn, progressively blocked a concomitant but sluggish release of fibrinopeptide A by the enzyme. When the clots obtained at less than 25 degrees C were warmed, they dissociated into soluble aggregates and monomers. Release of fibrinopeptide A then resumed, and a secondary coagulation followed. The aggregation induced by release of fibrinopeptide B itself involves a plasmin-susceptible segment located just distal to B in the B beta chain of fibrinogen, a segment previously shown to be of little importance in the aggregation induced by release of fibrinopeptide A.

Serological Assessment of the Quality of Wound Healing Processes in Crohn's Disease.

BACKGROUND AND AIMS: Crohn's disease (CD) is a chronic inflammatory condition characterized by continuous mucosal damage and ongoing wound healing of the intestines. The fibrinolytic system is involved in early parts of the wound healing process. Fibrin is a key mediator of primary blood clot formation and is formed by cross-linking of fibrinogen. To gain insights into the dynamics of wound healing in CD patients we investigated the conversion of fibrinogen into fibrin by the pro-peptide FPA, the amount of factor XIII cross-linked fibrin and total fibrin clot. METHODS: Serum samples of 35 CD patients, 15 non-inflammatory bowel disease (non-IBD) patients and 39 age-matched healthy controls were analyzed for three novel neo-epitope markers: D-fragment and D-dimer, reflecting the degradation of total fibrin clot and factor XIII cross-linked fibrin, as well as FPA, reflecting synthesis of fibrin. RESULTS: Crohn's disease patients had a significantly lower D-dimer level (p=0.0001) compared to healthy controls. Crohn's disease and non-IBD patients had a significantly higher level of FPA (p<0.0001) and D-fragment/D-dimer ratio (p<0.0001 and p=0.02). FPA, D-dimer and D-fragment/D-dimer ratio could distinguish CD patients from healthy controls with area under the curve of 0.92 (95% CI 0.83-0.97), 0.78 (95% CI 0.67-0.87) and 0.85 (95% CI 0.75-0.93), respectively. CONCLUSION: Wound healing parameters were clearly changed in CD patients. FPA levels were higher in CD patients as compared to healthy controls, indicating more ongoing wound healing. D-dimer levels were lower in CD patients than in healthy controls, indicating impaired wound healing due to poor quality of factor XIII cross-linked fibrin and clot resolution.

Exercise-induced hemostatic activation in patients with dilated cardiomyopathy in sinus rhythm.

Abnormalities of baseline hemostatic variables have been related to a hypercoagulable state in patients with chronic heart failure (CHF). Given that physical exercise leads to an activation of coagulation physiologically, this study addressed the question of whether the exercise-induced hemostatic activation is enhanced in patients with CHF. Ten patients with dilated cardiomyopathy (ejection fraction < 40%) and 10 healthy individuals (matched for sex, age and body mass index) were subjected to a maximal exercise test on a bicycle ergometer. Healthy subjects performed a second exercise test at a submaximal intensity level, in which oxygen consumption (VO2) was adjusted to the peak oxygen consumption (VO2peak) of the corresponding patient. Exercise testing had only marginal effects on markers of thrombin formation in patients and healthy individuals alike. In patients with CHF, exercise-induced changes in fibrinopeptide A, an index of fibrin formation, paralleled those observed in controls after submaximal exercise whereas most pronounced changes occurred in healthy subjects after maximal exercise. Plasmin-antiplasmin complexes increased almost three-fold with maximal exercise in both groups, thus indicating a marked formation of plasmin. Maximal physical exercise does not induce an exaggerated formation of thrombin and fibrin in CHF patients. The fibrinolytic response to exercise in terms of plasmin formation is not compromised in patients with dilated cardiomyopathy.