Clotting Factor Fibrinogen Research Articles

Haloperidol alters the behavioral, hematological and biochemical parameters of freshwater African catfish, Clarias gariepinus (Burchell 1822)

The presence of drugs and their metabolites in surface waters and municipal effluents has been reported in several studies, but their impacts on aquatic organisms are not yet well studied. The present study investigated the effects of exposure to the antipsychotic drug, haloperidol on the behavioral, hematological and biochemical parameters in juvenile Clarias gariepinus. The fishes were exposed to 0.12, 0.24 and 0.48 mg/L haloperidol for 15 days and later withdrawn from the toxicant and allowed to recover for 5 days. Blood was sampled on days 1, 5, 10, 15, and after the 5-day recovery for hematological and biochemical analysis. The pack cell volume (PCV), red blood cells (RBC), hemoglobin (Hb), reticulocytes and lymphocyte counts were significantly reduced in the exposed fish. The neutrophil counts were increased while that of monocytes, basophils and eosinophils were not affected by the drug. The mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were not different from the control on exposure to the drug. The activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and acid phosphatase (ACP); and serum creatinine, bile acid and bilirubin were increased on 15-day exposure to the drug. The activity of the clotting factor fibrinogen was reduced compared to the control after exposure to the drug. Haloperidol at concentrations used on 15-day exposure were toxic to fish, but the effect appeared short-lived, as it dissipated on 5-day withdrawal from the drug. While further studies are needed to ascertain the impact of prolonged exposure to environmentally relevant concentrations, caution is advised to avoid eco-toxicological damage to aquatic organisms.

Fibrin(ogen)-Pathogen Interactions Support Antimicrobial Host Defense Following Staphylococcus Aureus Peritonitis Infection

Staphylococcus aureus is a common gram-positive bacterium that is a frequent cause of community and hospital-acquired infections. The emergence of antibiotic resistant S. aureus hashighlighted a renewed need to better understand host-pathogen interactions for defining novel treatment strategies. The clotting factor fibrinogen is a target of several S. aureus virulence factors. Clumping factor A (ClfA) is a well characterized fibrin(ogen) binding protein known to mediate bacterial adhesion and clumping in blood plasma and has been shown to play an important role in several types of S aureus infections. Studies using Fib-/- (fibrinogen deficient) and FibAEK (mice expressing fibrinogen unable to form a fibrin polymer) indicated that fibrinogen and subsequent fibrin polymer formation are critical for clearance of USA300 S. aureus following peritonitis. Here, we tested the hypothesis that ClfA-fibrin(ogen)interactions are a key mechanistic feature of host antimicrobial function following S. aureus peritonitis. Analyses were performed with FibγΔ5 mutant mice, which express a mutant form of fibrinogen lacking the final 5 amino acids of the g chain encoding the bacterial ClfA binding motif. In vitro studies confirmed that fibrinogenWT supported robust bacterial adhesion and clumping whereas a complete absence of adhesion and clumping was observed using fibrinogenγΔ5. Infection studies of WT and FibγΔ5 mice revealed that ClfA-mediated, fibrin(ogen)- S. aureus interactions are an important determinant of host antimicrobial function in the context of peritonitis. Taken together, these data indicate that direct, ClfA-mediated binding of bacteria to fibrin(ogen) is a critical mechanistic component of host antimicrobial function following S. aureus peritonitis. DisclosuresNo relevant conflicts of interest to declare.

Sensitivity and reproducibility improvements in a human plasma immunoassay with removal of clotting factors

Interferences in human plasma immunoassay are severe challenge that affects the sensitivity and reproducibility of the assay. The clotting factor fibrinogen is a negatively charged protein and is one of the most common sources of interference in immunoassays, and its removal increases the sensitivity and reproducibility. Here, we present a highly sensitive and reproducible method for the detection of prostate specific antigen (PSA) in human plasma immunoassays. Protamine sulfate, a highly positively charged protein, was used to precipitate fibrinogen via ionic interaction to improve the sensitivity and reproducibility of human plasma immunoassay. In a sandwich ELISA for PSA using plasma and protamine-treated plasma samples, the limit of detection was improved from 413 pg/mL in plasma to 235 pg/mL in protamine-treated plasma samples, and the coefficient of variation known as a measure of reproducibility was significantly lowered by protamine treatment. The use of protamine sulfate in human plasma immunoassays for detection of PSA using quartz crystal microbalance (QCM) biosensors resulted in increased sensitivity and reproducibility by about 2-fold and 3-fold, respectively, relative to when not using protamine sulfate. Based on these results, protamine sulfate was the best choice to increase the sensitivity and reproducibility in immunoassays using plasma samples.

Selective cleavage of fibrinogen by diverse proteinases initiates innate allergic and antifungal immunity through CD11b

Proteinases are essential drivers of allergic airway disease and innate antifungal immunity in part through their ability cleave the clotting factor fibrinogen (FBG) into fibrinogen cleavage products (FCPs) that signal through Toll-like receptor 4 (TLR4). However, the mechanism by which FCPs engage TLR4 remains unknown. Here, we show that the proteinases from Aspergillus melleus (PAM) and other allergenic organisms rapidly hydrolyze FBG to yield relatively few FCPs that drive distinct antifungal mechanisms through TLR4. Functional FCPs, termed cryptokines, were characterized by rapid loss of the FBG α chain with substantial preservation of the β and γ chains, including a γ chain sequence (Fibγ390-396) that binds the integrin Mac-1 (CD11b/CD18). PAM-derived cryptokines could be generated from multiple FBG domains, and the ability of cryptokines to induce fungistasis in vitro and innate allergic airway disease in vivo strongly depended on both Mac-1 and the Mac-1-binding domain of FBG (Fibγ390-396). Our findings illustrate the essential concept of proteinase-activated immune responses and for the first time link Mac-1, cryptokines, and TLR4 to innate antifungal immunity and allergic airway disease.

Structural and Functional Study on the Interaction of Human Plasminogen and Protein H from Haemophilus Influenzae Type F

Haemophilus influenzae serotype f (Hif) resides in human respiratory tract, is an emerging pathogen causes invasive diseases. Recently, we annotated the whole genome of an invasive Hif isolate and showed that Hif simultaneously interacts with factor H and vitronectin by using the surface protein H (PH). Here, upon screening with various human plasma proteins, we found that PH can also interact with plasminogen, an important coagulation regulator of the blood. Plasminogen bound at a bacterial surface can be converted into plasmin and degrades complement factors such as C3b and C5 and thus suppresses the host innate immunity. In order to study the structural interaction between PH and human plasminogen, we cloned the lph gene encoding the protein PH in pETM30 vector and optimized the expression and purification of untagged recombinant PH. The dissociation constant (Kd) of the interaction between recombinant PH and plasminogen was 2.7 μM as measured by Biolayer interferometry and Microscale thermophoresis. We demonstrate that Hif can bind plasminogen, which is converted to plasmin that degrades complement factor C3b, C5 and blood clotting factor fibrinogen. We are now crystallizing PH, and the PH-plasminogen complex. Our study will spot light on deeper understanding of Hif virulence.

Fibrinogen concentrate versus placebo for treatment of postpartum haemorrhage: study protocol for a randomised controlled trial.

BackgroundPostpartum haemorrhage (PPH) is a major cause of maternal morbidity. Bleeding is caused by a combination of physical causes, such as failure of the uterus to contract or operations, and is made worse by impairment of the blood clotting system. A number of studies have shown that low levels of the blood clotting factor fibrinogen are associated with progression of bleeding, the need for invasive interventions and transfusions of red blood cells and fresh frozen plasma (FFP). This trial will investigate whether early infusion of fibrinogen concentrate during a major PPH, with the aim of correcting a low fibrinogen to a level that is normal for delivery, based on the Fibtem test, reduces the total number of allogeneic blood products (red blood cells, FFP, cryoprecipitate and platelets) transfused after study medication until discharge, compared to placebo.Methods/designThis is a prospective, randomised, double-blind placebo controlled trial. Women will enter an observational phase and if their Fibtem levels fall they will be randomised in the interventional phase. A total of 60 women will be randomised and women are eligible for the trial if they meet all of the following inclusion criteria: age 18 years or over, gestation ≥24 + 0 weeks, haemorrhage of about 1500 ml and on-going bleeding without another complication or haemorrhage of about 1000 ml and caesarean section/uterine atony/placental abruption/placenta praevia/cardiovascular instability or microvascular oozing. Participants with a Fibtem A5 < 16 mm will be randomly allocated to receive either a bolus infusion of fibrinogen concentrate or placebo (isotonic saline). The dose of fibrinogen concentrate or placebo will be calculated based on the woman’s ideal body weight for height and the measured Fibtem A5 with the aim of increasing the Fibtem A5 to 23 mm.DiscussionThe trial aims to provide evidence on the efficacy and safety of fibrinogen concentrate during acute bleeding in an obstetric setting.Trial registrationISRCTN ref: ISRCTN46295339 (01.07.2013); EudraCT: 2012-005511-11 (28.11.2012), UKCRN ref: 13940.

Cleavage of Fibrinogen by Proteinases Elicits Allergic Responses Through Toll-Like Receptor 4

Proteinases and the innate immune receptor Toll-like receptor 4 (TLR4) are essential for expression of allergic inflammation and diseases such as asthma. A mechanism that links these inflammatory mediators is essential for explaining the fundamental basis of allergic disease but has been elusive. Here, we demonstrate that TLR4 is activated by airway proteinase activity to initiate both allergic airway disease and antifungal immunity. These outcomes were induced by proteinase cleavage of the clotting protein fibrinogen, yielding fibrinogen cleavage products that acted as TLR4 ligands on airway epithelial cells and macrophages. Thus, allergic airway inflammation represents an antifungal defensive strategy that is driven by fibrinogen cleavage and TLR4 activation. These findings clarify the molecular basis of allergic disease and suggest new therapeutic strategies.

Quality of freeze‐dried (lyophilized) quarantined single‐donor plasma

Transfusion of plasma is a basic treatment for complex coagulopathies as well as in major blood loss. Early transfusion of plasma after trauma with major hemorrhage has been recommended by retrospective studies. However, the use of plasma is often hampered by the need to maintain a cold chain and the time needed for thawing fresh-frozen plasma (FFP). With freeze-dried (lyophilized) plasma (FDP) both difficulties can be avoided. Here, we describe the production, quality characteristics, and our experiences with FDP. Quarantine plasma samples were freeze-dried. The clotting factors fibrinogen, Factor (F)V, FVIII, FXI, von Willebrand factor (vWF), protein S, antithrombin, plasminogen, and plasmin inhibitor were determined after manufacturing and after storage at room temperature and refrigeration. Reported adverse transfusion events were evaluated and compared to that of FFP. Clinical effectiveness was estimated by inquiry among experienced users. Lyophilization resulted in a loss of coagulation factor activity between 0% and up to 20% to 25% (FVIII, vWF). When stored refrigerated, coagulation factors did not lose more than 10% of their activities. Storage at room temperature for 24 months mainly affected vWF/ristocetin cofactor activity and fibrinogen activity. From 2007 to 2011 more than 230,000 units of FDP were delivered. There were no reports about clinical ineffectiveness. The frequency of transfusion reactions was not different from that of FFP. Lyophilized plasma showed characteristics similar to FFP. Since FDP requires neither complex logistics nor time-consuming thawing, it allows rapid treatment of coagulopathies.

Structure of the Angiopoietin-2 Receptor Binding Domain and Identification of Surfaces Involved in Tie2 Recognition

The angiopoietins comprise a small class of secreted glycoproteins that play crucial roles in the maturation and maintenance of the mammalian vascular and lymphatic systems. They exert their effects through a member of the tyrosine kinase receptor family, Tie2. Angiopoietin/Tie2 signaling is unique among tyrosine kinase receptor-ligand systems in that distinct angiopoietin ligands, although highly homologous, can function as agonists or antagonists in a context-dependent manner. In an effort to understand this molecular dichotomy, we have crystallized and determined the 2.4 A crystal structure of the Angiopoietin-2 (Ang2) receptor binding region. The structure reveals a fibrinogen fold with a unique C-terminal P domain. Conservation analysis and structure-based mutagenesis identify a groove on the Ang2 molecular surface that mediates receptor recognition.

Postprandial Lipaemia, Haemostasis, Inflammatory Response and other Emerging Risk Factors for Cardiovascular Disease: The Influence of Fatty Meals

Adverse changes in postprandial metabolism may promote the development of cardiovascular disease (CVD) through a range of mechanisms. Since a large proportion of our day is spent in the postprandial state it is important to understand these post meal changes with respect to both the amount and type of nutrient consumed. Of particular importance appear to be the fatty meals, commonly eaten and which can induce significant postprandial lipaemia, accumulation of potentially atherogenic triglyceride-rich lipoprotein (TRL) remnants and formation of highly oxidisable small, dense low-density lipoproteins (LDL). In addition to these relatively well established lipaemic effects there is growing evidence that high-fat foods also have adverse effects on a number of the emerging CVD risk factors including haemostasis, mediators of inflammation and endothelial function. This review will consider the acute effects of high-fat feeding, investigating any differential effects of saturated and unsaturated fatty acids, on postprandial lipaemic profile, haemostatic clotting factors fibrinogen and factor VII, acute phase C-reactive protein (C-RP), inflammatory cytokines interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α), and vascular reactivity.

The effects of genotype and infant weight on adult plasma levels of fibrinogen, factor VII, and LDL cholesterol are additive.

High circulating levels of cholesterol, particularly low density lipoprotein (LDL) cholesterol and the clotting factors fibrinogen and factor VII, are associated with increased risk of myocardial infarction. Variations in the...

Association of Sex Hormones and Adiposity with Plasma Levels of Fibrinogen and PAI-1 in Postmenopausal Women

Blood levels of the clotting factor fibrinogen and tissue plasminogen activator inhibitor-1 (PAI-1), a primary inhibitor of fibrinolysis, have been positively linked to risk of coronary heart disease. The authors have reported previously that plasma fibrinogen appears to rise after menopause and to be reduced with use of postmenopausal hormonal therapy. There is also evidence to suggest that sex hormones may influence PAI-1. To examine whether plasma fibrinogen and PAI-1 antigen levels differ among older postmenopausal women according to use of hormone therapy and by blood level of estrogen and androgens, these variables were assessed among 277 healthy women aged 65-82 years, one half of whom were receiving therapy. The study population was drawn from the Study of Osteoporotic Fractures, Pittsburgh, Pennsylvania, during 1986-1988. Overall, results showed median PAI-1 levels to be lower on average with oral and transdermal use of hormone therapy (25.0 vs. 33.5 ng/ml, p < 0.01) and mean fibrinogen levels to be lower (279 vs. 295 mg/dl, p < 0.02) with use of oral estrogen (but not transdermal) therapy compared with women not receiving therapy. Among women not receiving therapy, PAI-1 and fibrinogen levels were not related to endogenous sex hormone levels, with the exception of a modest positive relation between PAI-1 and serum estrone concentrations (rs = 0.29). In addition, a markedly higher PAI-1 level was found for women with a preponderance of upper body fat, independent of obesity. In sum, results showed that older women receiving postmenopausal hormone therapy had more favorable plasma levels of the hemostatic factors PAI-1 and fibrinogen than did those not receiving therapy, which can be explained in large part by differences between the two groups in obesity and body fat distribution.

Cord blood clotting factors in neonates of smoking and non-smoking mothers.

Since smoking is known to influence hemostasis, the possible impact of maternal smoking on hemostatic variables in the newborn was studied. Cord blood clotting factors fibrinogen, factor VII, factor VIII:c and factor XIII were measured in 151 newborns. A significant reduction in birth weight and a rise in the placental/birth weight ratio was found in newborns of smoking mothers, which is in agreement with the literature. No differences in cord blood clotting factors were found between the smoking and non-smoking groups. A possible explanation for this, at least for lack of difference in fibrinogen levels, may be that fetal lungs were not directly exposed to smoke.