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OBJECTIVE: Acute coronary syndrome (ACS) is one of the leading causes of mortality, globally. Atherosclerosis is an underlying factor in ACS process and coagulative cascade is activated secondary to atherosclerotic plaque rupture. Fibrinopeptide A (FPA) takes an active role in thrombus formation and is an indicator of coagulative process. We aimed to evaluate serum FPA level in patients with ACS. METHODS: Patients diagnosed with ACS and chronic coronary syndrome (CCS), with non-obstructive coronary artery disease as a control group, were included in the study. Blood samples and demographic data of all patients were obtained at admission. Obtained data were compared between ACS and control groups. RESULTS: The study consisted of 107 patients with ACS and 69 patients with CCS. ACS group was older (p<0.001) with male preponderance (p<0.001), more likely to had hypertension (p<0.001), and had a higher smoking rate (p<0.001). Serum FPA level was highest in the ST elevated myocardial infarction group (p<0.001). FPA>3.38 ng/mL predicted ACS with 89.7% sensitivity and 78% specificity (AUC: 0.825, 95% CI 0.745-0.905; p<0.001). CONCLUSION: Serum FPA may be used for the differential diagnosis of ACS. In addition, patients with increased FPA may be considered to be given more aggressive antithrombotic medication. [ABSTRACT FROM AUTHOR]

Simple Summary: To date, the five-year survival rate of early stages of non-small cell lung cancer (NSCLC) is still disappointing and reliable prognostic factors are mandatory. Here, we performed in-depth high-throughput analyses of plasma circulating markers, including exosomal microRNAs and peptidome to identify a prognostic score. The miRnome profile selected the Exo-miR-130a-3p as the most overexpressed in relapsed patients. Peptidome analysis identified four progressively more degraded forms of fibrinopeptide A (FpA), which were depleted in relapse patients. Notably, a stepwise algorithm selected Exo-miR-130a-3p and the greatest FpA (2–16) to build a prognostic score, where high-risk patients had 18 months of median disease-free survival. Overexpression of miR-130a-3p cells led to a deregulation of pathways such as angiogenesis as well as the coagulation and metalloprotease, which might be linked to FpA reduction. The risk score integrating circulating markers may help clinicians predict early-stage NSCLC patients who are more likely to relapse after surgery. To date, the 5-year overall survival rate of 60% for early-stage non-small cell lung cancer (NSCLC) is still unsatisfactory. Therefore, reliable prognostic factors are needed. Growing evidence shows that cancer progression may depend on an interconnection between cancer cells and the surrounding tumor microenvironment; hence, circulating molecules may represent promising markers of cancer recurrence. In order to identify a prognostic score, we performed in-depth high-throughput analyses of plasma circulating markers, including exosomal microRNAs (Exo-miR) and peptides, in 67 radically resected NSCLCs. The miRnome profile selected the Exo-miR-130a-3p as the most overexpressed in relapsed patients. Peptidome analysis identified four progressively more degraded forms of fibrinopeptide A (FpA), which were depleted in progressing patients. Notably, stepwise Cox regression analysis selected Exo-miR-130a-3p and the greatest FpA (2-16) to build a score predictive of recurrence, where high-risk patients had 18 months of median disease-free survival. Moreover, in vitro transfections showed that higher levels of miR-130a-3p lead to a deregulation of pathways involved in metastasis and angiogenesis, including the coagulation process and metalloprotease increase which might be linked to FpA reduction. In conclusion, by integrating circulating markers, the identified risk score may help clinicians predict early-stage NSCLC patients who are more likely to relapse after primary surgery. [ABSTRACT FROM AUTHOR]

Female mosquitoes engage in blood feeding from their hosts to facilitate egg maturation but cease feeding once a sufficient blood meal has been acquired. Abdominal distention has been proposed as a contributing factor; however, it has also been suggested that there are chemical controls. In this study, we focus on negative chemical regulators of blood feeding, particularly those present in the host blood. Serum derived from animal blood inhibits the feeding of ATP, a phagostimulant of blood feeding in Aedes aegypti. Fibrinopeptide A (FPA), a 16-amino acid peptide cleaved from fibrinogen during blood coagulation, serves as an inhibitory factor in the serum. Our findings suggest that blood-feeding arrest in female mosquitoes is triggered by the detection of FPA in the host blood, which increases as blood coagulation proceeds in the mosquito's midgut, highlighting the role of host-derived substances as negative regulators of mosquito behavior. [Display omitted] • Host blood serum prevents mosquitoes from ATP feeding • Fibrinopeptide A, a by-product of blood coagulation, hampers ATP feeding • Fibrinopeptide A levels in mosquitoes increase during blood feeding • Forced release of fibrinopeptide A by a toxic agent blocks mosquito blood feeding Sakuma et al. describe that fibrinopeptide A (FPA), produced during the coagulation of host blood, inhibits blood feeding of Aedes aegypti. The amount of FPA in the mosquito's body increases as feeding proceeds. These findings indicate that a negative regulator for mosquito blood feeding is present in the host blood. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background/Aims: Atherosclerosis is a chronic inflammatory disease in the artery walls. Fibrinopeptide A (FPA) is a biomarker of the activation of coagulation system, and a high concentration of FPA in blood occurs in patients with ischemic heart disease etc. However, there exist few studies on the pathological effects of FPA in cardiovascular system. Therefore, the present study examined the effect of FPA on CRP expression in VSMCs and the molecular mechanisms. Methods: mRNA and protein expression was identified by quantitative real-time PCR and Western blot, respectively. Reactive oxygen species (ROS) and the immunofluorescence staining were observed by a fluorescence microscope. Plasma FPA and CRP level was determined by ELISA. Results: FPA induced the expressions of CRP, IL-1β and IL-6 in VSMCs, and anti-IL-1β and anti-IL-6 neutralizing antibodies partially reduced FPA-induced CRP expression in VSMCs. The subchronic administration of FPA to rats increased FPA level in plasma and CRP expression in the aortic artery walls. The further studies showed that FPA promoted superoxide anion generation in VSMCs. Antioxidant NAC antagonized FPA-stimulated superoxide anion generation and inhibited FPA-induced CRP expression in VSMCs. FPA activated ERK1/2 and p38 phosphorylation, and PD98059 and SB203580 reduced FPA-induced CRP expression. Moreover, NAC inhibited the activation of ERK1/2 and p38. In addition, FPA enhanced NF-κB level in the nuclei of VSMCs, and PDTC reduced FPA-induced expression of CRP. Conclusions: FPA induces CRP expression in VSMCs via ROS-ERK1/2/p38-NF-κB signal pathway. This finding for the first time provides an experimental evidence for pro-inflammatory effect of FPA.

Objective It remains unclear whether atrial fibrillation (AF) alone determines systemic changes in hemocoagulation. Our aim was to examine the prothrombin fragment F1+2 and fibrinopeptide A (FPA) as early markers of coagulation activity still in the first twenty-four hours of paroxysmal AF (PAF) and to correlate them with the arrhythmia onset. Methods 51 non-anticoagulated patients (26 men, 25 women, aged 59.84±1.6 years) and 52 controls (26 men, 26 women, aged 59.50±1.46 years) were sequentially selected. F1+2 and FPA plasma levels were measured by enzyme-linked immunoassays. Results F1+2 was significantly higher in patients (292.61pmol/L±14.03pmol/L vs 183.40pmol/L±8.38pmol/L; p<0.001). FPA was also substantially higher (4.47ng/mL±0.25 ng/mL vs 3.09ng/mL±0.15ng/mL, p<0.001). Among the potential predictors for these deviations: age, gender, BMI, PAF duration and CHA2DS2-VASc score, it was established that higher F1+2 and FPA plasma levels were independently associated only with PAF duration (p<0.05). Moreover, longer episodes were associated with higher values of F1+2 (Adjusted R² = 0.68) and FPA (Adjusted R² = 0.70). Conclusion Increased coagulation activity was present still in the first twenty-four hours of PAF clinical presentation. The disease itself was associated with increasing hypercoagulability over time, suggesting its importance as an independent risk factor for thromboembolic events. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the importance of fibrinopeptide-A and fibrinopeptide-B, which occur during the formation of D-dimer, the most commonly used laboratory parameter, in the early diagnosis of acute mesenteric ischemia (AMI). Materials and methods: This experimental study was performed in 30 male pathogen-free Wistar albino rats. The experimental animals were divided into 3 equal groups: Control group (n = 10), Sham group (n = 10) and Ischemia group (n = 10). Blood samples were taken 0, 1, 3, and 6 h after the simulation of mesenteric ischemia. Results: Fibrinopeptide-A and fibrinopeptide-B levels increased significantly in the first 6 h in the ischemic group, similar to the increase in D-dimer levels. The statistical change between 0, 1, 3 and 6 h was more significant for fibrinopeptide-A and fibrinopeptide-B. Conclusion: Fibrinopeptide-A and fibrinopeptide-B may be markers that can be used for early diagnosis of mesenteric ischemia, early diagnosis is highly important for decreasing mortality and morbidity. [ABSTRACT FROM AUTHOR]

Background & 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. [ABSTRACT FROM AUTHOR]

Context: Head injury causes disseminated intravascular coagulation as the most severe complication which is associated with high mortality. Elevated levels of markers of fibrinolysis such as D-dimer and fibrinopeptide A (FPA) have been correlated with poor outcome in these patients. Aim: The study aimed to correlate the levels of plasma fibrinogen, D-dimer, and FPA with outcome in patients with isolated head trauma. Settings and Design: This cross-sectional descriptive study was conducted in the Departments of Pathology and Neurosurgery, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi, on 100 patients admitted within 12 h of isolated head trauma. Subjects and Methods: Plasma fibrinogen, D-dimer, and FPA were measured in 100 patients admitted within 12 h of isolated head trauma. While plasma fibrinogen and D-dimer were estimated in all patients, FPA was measured in 45 patients. Statistical Analysis: SPSS (20.2) software was used for mean, standard deviation, and median values of the quantitative parameters, and for all qualitative parameters, their frequencies were obtained. P < 0.05 was considered significant. Results: Elevated D-dimer (>250 ng/ml) and FPA (>3 ng/ml) were observed in 64% and 91.1% patients, respectively. Both D-dimer and FPA were elevated in 66.6% of patients. Disseminated intravascular coagulation (DIC) score, calculated using standard criteria, was ≥5 in 28% of patients indicating overt DIC. Hypofibrinogenemia was observed in 48% of patients. D-dimer, FPA, and DIC score was significantly (P < 0.001) higher and plasma fibrinogen significantly (P < 0.001) lower in nonsurvivors as compared to survivors. Elevated D-dimer and FPA and low fibrinogen levels were seen in patients irrespective of severity of injury. Conclusions: Elevated D-dimer and FPA were frequently observed in patients with isolated head trauma. As these markers rise soon after injury and indicate poor outcome, their measurement will help identify patients who will benefit with additional therapy, thus reducing morbidity and mortality. [ABSTRACT FROM AUTHOR]

The importance of antimicrobial peptides (AMPs) in relation to the survival of invertebrates is well known. The source and the mode of action on the insects' immune system of these molecules have been described from different perspectives. Insects produce their own AMPs as well as obtain these molecules from various sources, for example by absorption through the intestinal tract, as previously described for Boophilus microplus. Blood-sucking barber bug Triatoma infestans attracts social, economic and medical interest owing to its role in the transmission of Chagas disease. Despite new studies, descriptions of AMPs from this insect have remained elusive. Thus, the aims of this work were to characterize the antimicrobial potential of human fibrinopeptide A (FbPA) obtained from the T. infestans haemolymph and identify its natural source. Therefore, FbPA was isolated from the T. infestans haemolymph through liquid chromatography and identified by mass spectrometry. This peptide exhibited antimicrobial activity against Micrococcus luteus. Native FbPA from human blood and the synthetic FbPA also exhibited antimicrobial activity. The synthetic FbPA was conjugated with fluorescein isothiocyanate and offered to the insects. The haemolymph collected after 72 h exhibited fluorescence at the same wavelength as fluorescein isothiocyanate. Our experiments show that beyond intrinsic AMP production, T. infestans is able to co-opt molecules via internalization and may use them as AMPs for protection.

The importance of antimicrobial peptides (AMPs) in relation to the survival of invertebrates is well known. The source and the mode of action on the insects' immune system of these molecules have been described from different perspectives. Insects produce their own AMPs as well as obtain these molecules from various sources, for example by absorption through the intestinal tract, as previously described for Boophilus microplus. Blood-sucking barber bug Triatoma infestans attracts social, economic and medical interest owing to its role in the transmission of Chagas disease. Despite new studies, descriptions of AMPs from this insect have remained elusive. Thus, the aims of this work were to characterize the antimicrobial potential of human fibrinopeptide A (FbPA) obtained from the T. infestans haemolymph and identify its natural source. Therefore, FbPA was isolated from the T. infestans haemolymph through liquid chromatography and identified by mass spectrometry. This peptide exhibited antimicrobial activity against Micrococcus luteus. Native FbPA from human blood and the synthetic FbPA also exhibited antimicrobial activity. The synthetic FbPA was conjugated with fluorescein isothiocyanate and offered to the insects. The haemolymph collected after 72 h exhibited fluorescence at the same wavelength as fluorescein isothiocyanate. Our experiments show that beyond intrinsic AMP production, T. infestans is able to co-opt molecules via internalization and may use them as AMPs for protection. [ABSTRACT FROM AUTHOR]

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

Coagulation is a highly conserved process occurring after an injury to a blood vessel and resulting in hemostasis. In the thrombus microenvironment, finely orchestrated events restore vessel integrity through platelet activation, adhesion, and aggregation (primary hemostasis), followed by the coagulation cascades, thrombin generation, and fibrin clot deposition (secondary hemostasis). Several studies on cancer have provided insight into dramatic changes to coagulation-related events (i.e., fibrin clot deposition, fibrinolysis) during tumor pathogenesis, progression, and metastasis, in addition to a tumor-driven systemic activation of hemostasis and thrombosis (Trousseau's syndrome). Diverse molecular and cellular effectors participate in the cross talk between hemostasis and tumors. Here, we focus on some aspects of the interconnection between cancer biology and hemostatic components, with particular attention to some key coagulation-related proteins (e.g., tissue factor, thrombin, fibrinogen, and D-dimers) in the particular case of gastric cancer (GC). Recent advances in deciphering the complex molecular link between GC and the coagulation system are described, showing their important roles in better management of patients affected by GC. [ABSTRACT FROM AUTHOR]

Ankylosing spondylitis (AS) is an autoimmune rheumatic disease that mostly affects the axial skeleton. This study aimed to investigate reliable diagnostic serum biomarkers for AS. Serum samples were collected from 20 AS patients and 20 healthy controls (HCs) and analyzed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The differential metabolites between the AS patients and HCs were profiled using univariate and multivariate statistical analyses. Pathway analysis and a heat map were also conducted. Random forest (RF) analysis and the least absolute shrinkage and selection operator (LASSO) were used to establish predictive and diagnostic models. After controlling the variable importance in the projection (VIP) value > 1 and false discovery rate (FDR) < 0.05, a total of 61 differential metabolites were identified from 995 metabolites, which exhibited significant differences in the pathway analysis and heat map between the AS patients and HCs. RF as a predictive model also identified differential metabolites with 95% predictive accuracy and a high area under the curve (AUC) of 1. A diagnostic model comprising nine metabolites (cysteinylglycine disulfide, choline, N6, N6, N6-trimethyllysine, histidine, sphingosine, fibrinopeptide A, glycerol 3-phosphate, 1-linoleoyl-GPA (18:2), and fibrinopeptide A (3-16)) was generated using LASSO regression, capable of distinguishing HCs from AS with a high AUC of 1. Our results indicated that the UPLC-MS/MS analysis method is a powerful tool for identifying AS metabolite profiles. We developed a nine-metabolites-based model serving as a diagnostic tool to separate AS patients from HCs, and the identified diagnostic biomarkers appeared to have a diagnostic value for AS., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Fibrinogen is a secreted glycoprotein that is synthesized in the liver, although recent in situ hybridization data support its expression in the brain. It is involved in blood clotting and is released in the brain upon injury. Here, we report changes in the extracellular levels of fibrinogen α-chain-derived peptides in the brain after injections of saline and morphine. More specifically, in order to assess hippocampus-related working memory, an approach pairing in vivo microdialysis with mass spectrometry was used to characterize extracellular peptide release from the hippocampus of rats in response to saline or morphine injection coupled with a spontaneous alternation task. Two fibrinopeptide A-related peptides derived from the fibrinogen α-chain - fibrinopeptide A ( ADTGTTSEFIEAGGDIR) and a fibrinopeptide A-derived peptide ( DTGTTSEFIEAGGDIR) - were shown to be consistently elevated in the hippocampal microdialysate. Fibrinopeptide A was significantly upregulated in rats exposed to morphine and spontaneous alternation testing compared with rats exposed to saline and spontaneous alternation testing ( P < 0.001), morphine alone ( P < 0.01), or saline alone ( P < 0.01), respectively. The increase in fibrinopeptide A in rats subjected to morphine and a memory task suggests that a complex interaction between fibrinogen and morphine takes place in the hippocampus. [ABSTRACT FROM AUTHOR]

Abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitously distributed endocrine disruptors. To investigate peptide changes in the sera of rats chronically exposed to TCDD and to explore the association of these changes with liver morphology, TCDD was administrated to male rats at doses of 140, 350, and 875ng/kg/week for 29 weeks. Serum was collected and proteomic analysis was performed using automated Bruker Daltonics ClinProt with matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. One peptide at 1740.89 was found to be significantly decreased and further identified with nano LC–MS/MS system. The MS BLAST homology search engine reported the peptide to be a partial sequence of fibrinopeptide A. Liver fatty degeneration and necrosis were assessed by hematoxylin and eosin staining. Liver fatty degeneration and necrosis were both found to be significantly increased after TCDD exposure. Levels of fibrinopeptide A were significantly correlated with liver fatty degeneration and necrosis. [Copyright &y& Elsevier]

Abstract: Introduction: Various dysfibrinogenemias have been described worldwide. This paper describes two new cases of dysfibrinogenemia identified in the Czech Republic. Materials and methods: The proposita of fibrinogen Nový Jičín, a 12-year-old girl, presented with hemorrhagic complications, low Clauss fibrinogen level (0.3 g/l) and prolonged both thrombin (70.8 s) and reptilase (>180 s) time. Her mother and sister both presented with normal coagulation tests, normal fibrinogen level and reported no history of bleeding. The carriers of the fibrinogen Praha II were a 31-year-old man and his 11-year-old daughter. They both presented with low fibrinogen Clauss level (0.88 g/l) and prolonged thrombin and reptilase time. To identify the genetic mutation responsible for these dysfibrinogens, genomic DNA extracted from the blood was analyzed. The presence of the mutant chains in the circulation was determined by MALDI-TOF mass spectroscopy. Scanning electron micrographs of the patients'' fibrin clots were obtained. Results: The kinetics of fibrinopeptide release and fibrin polymerization were impaired for both fibrinogen Nový Jičín and Praha II. DNA sequencing showed heterogeneous fibrinogen Aα R16C mutation in the fibrinogen Nový Jičín case and heterogeneous fibrinogen Aα R16H in the fibrinogen Praha II case. The mutant chains were found to be expressed to the circulation by MALDI-TOF mass spectroscopy. Scanning electron micrographs of the patient''s fibrin clot were found to be abnormal. Conclusions: The case of dysfibrinogenemia Aα R16C-fibrinogen Nový Jičín and the case of dysfibrinogenemia Aα R16H were found by routine coagulation testing and were genetically identified. [Copyright &y& Elsevier]

Abstract: Fibrinogen adsorption and more recently fibrin formation at interfaces has been reported to depend on surface properties of the underlying substrate. To provide insight into the surface-dependent mechanism of fibrinopeptide A (FpA) release and fibrin formation, the accessibility and susceptibility of FpA to thrombin-catalyzed fibrinopeptide cleavage were examined using polyclonal anti-FpA IgG binding and surface plasmon resonance (SPR). The amount of accessible FpA on adsorbed fibrinogen was significantly influenced by surface properties of the underlying substrate (methyl- and carboxyl-terminated self-assembled monolayers). Roughly 2.7 times more FpA was available on fibrinogen adsorbed at the hydrophobic vs. negatively charged surface. Upon exposure of adsorbed fibrinogen to thrombin, 100% of the available FpA was enzymatically cleaved at both surfaces, indicating that the extent of FpA release and fibrin formation is a function of the surface-dependent FpA availability. The results presented herein suggest negatively charged surfaces impair FpA accessibility, and therefore lead to reduced FpA release and subsequent fibrin formation. As such, negatively charged surfaces may be useful in minimizing surface-induced thrombosis initiated via fibrin formation thereby aiding in the development of more biocompatible blood-contacting devices. [Copyright &y& Elsevier]

Abstract: High intake of saturated fat is a predictor of coronary heart disease mortality. The phenomenon of postprandial angina pectoris has been described many years ago. Although earlier studies have demonstrated postprandial activation of coagulation factors VII and XII, platelets and monocytes, conclusive evidence for intravascular fibrin formation after a fat-rich meal has not been reported yet. The present study included 33 healthy physicians (7 females, 26 males) with a mean age of 42 years (range 27–62 years), and 27 coronary heart disease patients (8 females, 19 males) with a mean age of 63 years (range 47–81 years). Of the coronary heart disease patients, 26/27 were treated with acetylsalicylic acid and 25/27 with lipid-lowering drugs simvastatin or atorvastatin. Blood samples were drawn 30–60min before and 30–60min after a dinner consisting of rye bread with liversausage and black pudding as hors d''oeuvre, lettuce with smoked bacon in a lard dressing, stuffed fried goose with red cabbage, potato dumplings and sweet chestnuts, and white and brown mousse au chocolat. Average intake per person was 3760kcal, with 125.9g protein, 238.0g fat and 268.9g carbohydrate. We measured a significant postprandial increase in fibrinopeptide A (FpA) levels from 1.14±1.23μg/l to 4.18±2.86μg/l (p <0.0001) in healthy probands, and 4.66±13.61μg/l to 12.80±15.04μg/l (p <0.0001) in coronary heart disease patients. Triglycerides increased from 137.6±60.5 to 201.5±75.0mg/dl in healthy probands and from 211.9±94.6 to 273.6±122.5mg/dl in coronary heart disease patients. Fat-rich meals may cause procoagulant episodes, which may promote vascular complications such as myocardial infarction, transient ischemia attacks in susceptible persons. [Copyright &y& Elsevier]

Abstract: The mechanisms involved in fibrin gel formation are reviewed. Furthermore, a new concept of the role of fibrinopeptide release in this process is presented. [Copyright &y& Elsevier]

Introduction: Clinical trials evaluating direct thrombin inhibitors in unstable coronary artery disease (CAD) have been disappointing. The hypothesis tested in the present study was that these agents may inhibit the anticoagulant effect of thrombin to a further extent than the procoagulant effect of thrombin. Materials and methods: We studied both reversible and irreversible thrombin inhibitors and compared the effects of each inhibitor on activated protein C (APC) generation vs. the effect on fibrinopeptide A (FPA) generation. A mixture of protein C, thrombin inhibitor, fibrinogen, fibrin polymerisation blocker and thrombin was incubated with thrombomodulin (TM)-expressing human saphenous vein endothelial cells (HSVECs). The inhibitors investigated were melagatran, inogatran, hirudin, hirugen, d-Phe-d-Pro-d-arginyl chloromethyl ketone (PPACK), and antithrombin (AT) alone or in combination with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). Results: All agents, except hirugen, inhibited APC and FPA generation in a dose-dependent manner. FPA inhibition/APC inhibition ratios, based on IC50 for inogatran, melagatran, hirudin, PPACK, AT, AT-UFH and AT-LMWH were 1.73, 0.85, 0.55, 2.1, 0.5, 0.65 and 3.1 respectively. Conclusions: All agents, except hirugen, inhibited APC and FPA generation approximately to a similar extent. Thus, it can be inferred that the poor efficacy of thrombin inhibitors in recent clinical trials in patients with unstable CAD is unlikely to be a consequence of their effects on the protein C system. [Copyright &y& Elsevier]

Bradykinin, RPPGFSPFG, has been reported to be an inhibitor of thrombin’s roles in blood clotting, platelet activation, and cellular permeability. The exact target, magnitude, and type of inhibition occurring are not well characterized. Based on the individual kinetic parameters calculated here, bradykinin is classified as a weak competitive inhibitor against hydrolysis of S-2238 and of a PAR4-like peptide. The Km values increased twofold in the presence of bradykinin, whereas the kcat values remained constant. The Ki values ranged from 170 to 326 μM. Other biochemical studies indicated that bradykinin inhibits release of fibrinopeptide A from fibrinogen. Furthermore, bradykinin hindered the time required for fibrin clot formation. The weak inhibitions observed in vitro suggest that the direct effects of bradykinin on the thrombin active site become significant only at high concentrations, levels that may be difficult to achieve physiologically. Clearly, bradykinin can target thrombin but whether this direct interaction can be achieved in vivo and is sufficient to elicit a response without contributions from other cofactors requires further investigation. [Copyright &y& Elsevier]

Introduction: The exchange of Aα 16, Arg for Cys or His is the most common molecular defect in dysfibrinogenemia directly affecting the thrombin cleavage site involved in fibrinopeptide A (FPA) release. Other amino acid exchanges within the fibrinopeptide A have been only rarely reported. Materials and methods: In clinically asymptomatic dysfibrinogenemic patients with low functional plasma fibrinogen (Fg) levels and prolonged thrombin time but normal or slightly prolonged batroxobin (reptilase) time, mutation analysis was carried out by direct sequencing of the coding regions of the three fibrinogen genes. Isolated fibrinogen was functionally characterized for thrombin- or batroxobin-induced fibrinopeptide release and fibrin formation. Fibrinogen and fibrinopeptides were structurally studied by electrophoretic techniques or high-performance liquid chromatography. Results and conclusions: Molecular analysis revealed heterozygosity for a novel missense mutation T1182C in the FGA gene causing the amino acid exchange Aα 9, Leu→Pro. Fibrin generation induced by thrombin was moderately impaired, whereas batroxobin-induced fibrin formation was almost normal. Release of the abnormal fibrinopeptide A by thrombin was delayed but fibrin monomer aggregation was almost normal. Cleavage of Aα chains by batroxobin was only slightly delayed. Fibrinopeptides A of the patient fibrinogen did not show any gross abnormality in chromatographic behaviour. This new molecular variant designated fibrinogen Magdeburg I supports the view that amino acid residue Leu-9 in the Aα chain as part of a small hydrophobic cluster is involved in the interaction with an apolar binding site of thrombin, thus adding to our understanding of the thrombin–fibrinogen interaction crucial in coagulation. [Copyright &y& Elsevier]

Objective: Effects of aprotinin in off-pump coronary artery bypass (OPCAB) surgery have not yet been described. This study analyses hemostasiologic changes and potential benefit in OPCAB patients treated with aprotinin. Methods: In a prospective, double-blind, randomized study 47 patients undergoing OPCAB surgery were investigated. Patients received either aprotinin (2×106 KIU loading dose and 0.5×106 KIU/h during surgery, n=22) or saline solution (control, n=25). Activated clotting time was adjusted to a target of 250 s intraoperatively. Blood samples were taken up to 18 h postoperatively: complete hematologic and hemostasiologic parameters including fibrinopeptide A (FPA) and D-dimer in a subgroup of 31 patients were analyzed. Blood loss, blood transfusion and other clinical data were collected. Results: Both groups showed comparable demographic and intraoperative variables. Forty-one (87%) patients of the whole study group received aspirin within 7 days prior to surgery. Number of grafts per patient were comparable (2.9±1.0 [mean±SD] in the aprotinin group and 2.8±1.2 in control, P=0.83). Blood loss during the first 18 h in intensive care unit was significantly reduced in patients treated with aprotinin (median [25th–75th percentiles]: 500 [395–755] ml vs. 930 [800–1170] ml, P<0.001). Postoperatively only two patients (10%) in the aprotinin group received packed red blood cells, whereas eight (35%) in the control group (P=0.07). Perioperatively FPA levels reflecting thrombin generation were elevated in both groups. The increase in D-dimer levels after surgery was significantly inhibited in the aprotinin group (P<0.001). Early clinical outcome was similar in both groups. Conclusions: Aprotinin significantly reduces blood loss in patients undergoing OPCAB surgery. Inhibition of enhanced fibrinolysis can be observed. FPA generation during and after OPCAB surgery seems not to be influenced by aprotinin. [Copyright &y& Elsevier]

Synthetic direct inhibitors of factor Xa are capable of prolonging the global anticoagulant assay times in a concentration-dependent fashion. The relative degree of thrombin generation inhibition at an equivalent prolongation is not similar to the results observed with heparins and oral anticoagulant drugs. In addition, the direct factor Xa inhibitors prolong the Russell's viper venom test (RVVT) and Heptest clotting times. Ecarin clotting time (ECT) and thrombin time (TT) remain unaffected. The kinetics of factor Xa inhibition are markedly different than those observed with pentasaccharide and heparins. Therefore, the methods developed for heparins and pentasaccharides may not be applicable for the monitoring of factor Xa inhibitors. To test the feasibility of using the prothrombin time (PT), International Normalized Ratio (INR), activated partial thromboplastin time (aPTT), Heptest, thrombin time, RWT, ECT, and a modified anti-Xa amidolytic assay, to monitor a synthetic factor Xa inhibitor, normal human pool plasma samples were spiked with a synthetic factor Xa inhibitor in the concentration range of 0 to 1 µg/mL and 0 to 25 µg/mL. Different laboratory tests were performed and INR and other ratios were calculated. The anticoagulant effects on whole blood were measured using the activated clotting time (ACT). Further studies on the effect of factor Xa inhibitor on platelet aggregation; factor II, VII, and X functional levels; and fibrinopeptide A (FPA) generation were carried out at equivalent INR levels in comparison to oral anticoagulant and antithrombin agents. FPA generation at equivalent anticoagulant level in comparison to heparin (twice the baseline) was also carried out. Factor Xa inhibitor produced a concentration-dependent prolongation of the ACT. ACT was doubled at a concentration of 4 to 5 µg/mL. There was a marked difference in the prolongation of the PT by a synthetic factor Xa inhibitor dependent on the ISI of the PT reagent... [ABSTRACT FROM AUTHOR]

Fibrinopeptide A (FPA) was systematically investigated in 74 patients with acute leukaemia at different stages of the disease (50 with non-lymphocytic leukaemia, ANLL; 24 with lymphocytic leukaemia, ALL). At diagnosis, 75% of the cases had high FPA levels (86% in ANLL and 54% in ALL) with significantly higher levels in ANLL than in ALL (13.4 vs 4.4 ng/ml; p<0.001). Patients with DIC (20 cases in ANLL and 1 case in ALL) had significantly higher levels ( p<0.001). FPA levels were neither correlated with fibrinogen or FDP levels nor with blast cell count. During chemotherapy, median FPA did not show significant changes whereas, at the end of therapy, a return toward normality was generally observed both in ALL and ANLL apart from the group of patients with acute promyelocytic leukaemia. Among the 24 patients who entered post-remission follow-up (13 ANLL and 11 ALL), 10 cases out of the 11 relapsing (6/6 with ANLL and 4/5 with ALL) had increased FPA 1 to 2 months before the ascertainment of the relapse. However, 16% and 9% of the samples obtained on different occasions, respectively from ANLL and ALL cases in maintained first remission, showed FPA above the normal limit. This study demonstrates that subclinical activation of blood coagulation, as indicated by high FPA level, is common both in lymphocytic and non-lymphocytic leukemia and suggests that this phenomenon is related to disease activity. [ABSTRACT FROM AUTHOR]

The effect of an immunotherapy with Corynebacterium parvum on the blood coagulation system was investigated in a randomized trial of 18 patients with metastatic breast cancer. All patients received cytostatic therapy. Additionally, C. parvum was given intravenously on day 15 of the cytostatic cycle (group I) or on day 1 (group II) or not at all (group III). Fibrinopeptide A increased within 2 h after intravenous administration of C. parvum in groups I and II and normalized after 24 h ( p<0.05). Platelet counts decreased continuously in all treatment groups ( p<0.05). Prothrombin time, fibrinogen concentration, factor VIII:C and factor VIIIR:Ag were not affected. The fibrinolytic activity showed a slight but not statistically significant increase after intravenous administration of C. parvum. The data suggest that plasma hypercoagulability is induced or enhanced in man even after small intravenous doses of C. parvum. [ABSTRACT FROM AUTHOR]