Effects of pathogen reduction technology and storage duration on the ability of cryoprecipitate to rescue induced coagulopathies in vitro.

BACKGROUND: Fibrinogen concentrates and cryoprecipitate are currently used for fibrinogen supplementation in bleeding patients with dysfibrinogenemia. Both products provide an abundant source of fibrinogen but take greater than 10 min to prepare for administration. Fibrinogen concentrates lack coagulation factors (i.e., factor VIII [FVIII], factor XIII [FXIII], von Willebrand factor [VWF]) important for robust hemostatic function. Cryoprecipitate products contain these factors but have short shelf lives (<6 h). Pathogen reduction (PR) of cryoprecipitate would provide a shelf-stable immediately available adjunct containing factors important for rescuing hemostatic dysfunction. STUDY DESIGN AND METHODS: Hemostatic adjunct study products were psoralen-treated PR-cryoprecipitated fibrinogen complex (PR-Cryo FC), cryoprecipitate (Cryo), and fibrinogen concentrates (FibCon). PR-Cryo FC and Cryo were stored for 10 days at 20-24°C. Adjuncts were added to coagulopathies (dilutional, 3:7 whole blood [WB]:normal saline; or lytic, WB + 75 ng/ml tissue plasminogen activator), and hemostatic function was assessed by rotational thromboelastometry and thrombin generation. RESULTS: PR of cryoprecipitate did not reduce levels of FVIII, FXIII, or VWF. PR-Cryo FC rescued dilutional coagulopathy similarly to Cryo, while generating significantly more thrombin than FibCon, which also rescued dilutional coagulopathy. Storage out to 10 days at 20-24°C did not diminish the hemostatic function of PR-Cryo FC. DISCUSSION: PR-Cryo FC provides similar and/or improved hemostatic rescue compared to FibCon in dilutional coagulopathies, and this rescue ability is stable over 10 days of storage. In hemorrhaging patients, where every minute delay is associated with a 5% increase in mortality, the immediate availability of PR-Cryo FC has the potential to improve outcomes.

Spray-dried plasma deficient in high-molecular-weight multimers of von Willebrand factor retains hemostatic properties.

BACKGROUND: Dried plasmas can overcome logistical barriers that prevent fresh frozen plasma (FFP) usage in acute resuscitation, but processing of these products can detrimentally alter the composition. Spray-dried plasma (SpDP) from single units is deficient in high-molecular-weight multimers of von Willebrand factor (vWF), a critical facilitator of platelet adhesion and thrombus formation. We hypothesized that converting high-molecular-weight multimers to smaller-molecular-weight multimers would retain vWF's capacity to mediate platelet adhesion. STUDY DESIGN AND METHODS: SpDP obtained from untreated FFP was reconstituted with glycine-hydrochloric acid (HCl) and glycine (20 mM:50 mM) or pretreated with glycine-HCl (20 mM) or glycine-glycine-HCl (20 mM:50 mM) and reconstituted with water. In vitro hemostatic potential of SpDPs versus FFP or FFP spiked with 70 mM of glycine was evaluated, leading to a more detailed in vitro study of glycine-HCl-glycine (20 mM:50 mM) pretreated SpDP. Plasmas were combined with RBCs and platelets to observe global coagulation response. RESULTS: While vWF-ristocetin cofactor activity is significantly decreased (-41.13%; p < .0001) in SpDP, a model of vWF-mediated platelet adhesion to collagen under flow showed enhanced function (+13%; p < .01). Fewer microparticles, particularly of platelet origin, were observed in SpDP versus FFP (p < .0001). Small but significant differences in thromboelastography results were observed, although SpDP and FFP were within normal ranges. CONCLUSION: Comparable coagulability was observed in FFP and SpDP. The apparent paradox between vWF-ristocetin cofactor assay and vWF-mediated platelet adhesion may be explained by the increase in smaller multimers of vWF in SpDP, producing different outcomes in these assays.

Haemostatic changes in urogenital schistosomiasis haematobium: a case-control study in Gabonese schoolchildren.

In many tropical areas schistosomiasis is a major health problem causing hepatosplenic, intestinal or urogenital complaints. Hepatosplenic schistosomiasis mansoni is also characterized by blood coagulation abnormalities. Liver pathology plays a role in the development of haemostatic changes and the parasitic infection may directly affect coagulation. However, these contributing factors cannot be studied separately in hepatosplenic schistosomiasis infections. This pilot study provides insight in haemostatic changes in urinary schistosomiasis by studying coagulation parameters in schistosomiasis haematobium-infected Gabonese schoolchildren. Selection on urinary schistosomiasis patients without hepatosplenic complaints allows for the investigation of the direct effects of the parasite on haemostasis. Levels of von Willebrand Factor (VWF) antigen, active VWF and osteoprotegerin were elevated, indicating inflammation-mediated endothelial activation. In contrast to hepatosplenic schistosomiasis, thrombin-antithrombin complex and D-dimer levels were not affected. Despite its small sample size, this study clearly indicates that Schistosoma haematobium directly alters the activation status of the endothelium, without initiation of coagulation.

Gelatin-Based Hemostatic Agents: Histopathologic Differences.

PURPOSE: To delineate the histopathologic appearance of gelatin-based hemostatic agents, Surgiflo, Gelfoam, and Floseal, which are used by ophthalmic plastic surgeons, and which may incidentally be found as foreign materials in histopathologic tissue samples. METHODS: Histopathologic analysis was performed with hematoxylin-eosin, periodic acid-Schiff, Masson trichrome, and elastin staining on tissue samples in which gelatin-based agents were found. To better characterize these materials, similar analyses were performed on in vitro samples of commonly used gelatin-based hemostatic agents. RESULTS: Surgiflo and Gelfoam are composed of small stellate pieces of gelatin with a smooth, homogeneous quality. In tissues, they are faintly positive with periodic acid-Schiff staining, amphophilic with Masson trichrome staining, and ink-black with elastin staining. Floseal has a distinctly different morphology of large rectangular sheets, yet almost identical in vitro staining properties. DISCUSSION: While the morphology of the gelatin-based hemostatic agents is consistent under various conditions, the staining properties of these materials differ based on whether they have been in contact with human tissue. CONCLUSIONS: Gelatin-derived hemostatic agents are best identified based on their morphologic characteristics. Elastin staining highlights these materials prominently within tissue samples and may be helpful in distinguishing them from other foreign materials.

Magnetic Resonance Imaging Appearance and Mechanism of Action of Five Hemostatic Agents Used in Neurosurgery.

OBJECTIVE: To describe the magnetic resonance (MR) image appearance of 5 hemostatic agents placed in the brain, and to review their clinical application. STUDY DESIGN: Descriptive ex vivo and in vivo study. ANIMALS: Canine cadavers (n=4), client-owned dogs (n=4). METHODS: Heads from 4 canine cadavers were used, each with 5 hemostatic agents placed in specific locations in the brain. Hemostatic agents were used in their native form in 2 cadaveric brains, and in 2 others the materials were saturated with fresh whole blood prior to placement to mimic application in a field of active hemorrhage. The heads underwent MR imaging and the images were reviewed. Postoperative MRI images from 4 dogs undergoing brain tumor resection were retrospectively reviewed and compared to the images from the cadavers. All clinical cases and cadaveric specimens underwent surgical closure prior to MR imaging including placement of titanium mesh over the craniotomy defect with a dural graft of porcine small intestinal submucosa (SIS) sealed with Tisseel (fibrin sealant). RESULTS: The SIS and Tisseel used in the dural graft were consistently indistinguishable from the surrounding tissues on MR images. The MR imaging appearance of the remaining 4 hemostatic agents (Gelfoam, Avitene, Surgicel, and Floseal) placed on the surface or in the parenchyma of canine brain, varied with MR sequence weighting and blood saturation. CONCLUSION: Accurate evaluation of the degree of brain tumor resection on postoperative MR images requires careful differentiation between hemorrhage, residual tumor, and hemostatic agents implanted.

[Composition of 359 kidney stones from the East region of Algeria]. / Détermination de la composition de 359 calculs du haut appareil urinaire collectés dans la région Est-algérien.

PURPOSE: Determine stones composition of the upper urinary tract in the eastern region of Algeria. METHODS: Our study focuses on a set of 359 stones of the upper urinary tract collected between January 2007 and December 2012 at hospitals in the eastern region of Algeria and analyzed by Fourier transform infrared spectroscopy. RESULTS: The male/female ratio was only 1.32. Calcium oxalate prevailed in 68.5% of stones and 49.3% of nuclei, mainly as whewellite (51.8% of stones and 37.9% of nuclei vs 16.7% and 11.4% respectively for weddellite). Carbapatite prevailed in 15% of stones and 29.8% of nuclei. The struvite, identified in 11.1% of calculi, prevailed in 3.9% of stones and 3.1% of nuclei. Among purines, uric acid prevailed with frequencies quite close to 8.9% and 7% respectively in the stone and in the nucleus while the ammonium urate prevailed in only 0.3% of stones and 3.3% of nuclei. The cystine frequency was 3.6% in both stone and nucleus. The frequency of stone with umbilication was 26.2%. Whewellite was the main component of umbilicated stones with Randall's plaque. CONCLUSION: Our results suggest that stones of the urinary tract in the Algerian east region resemble those observed in industrialized countries. Some features such as stones location, the whewellite prevalence, the frequencies of main components in both the stone and the nucleus as well as the formation of stones on renal papilla confirm this trend. LEVEL OF EVIDENCE: 4.

High-performance liquid chromatographic determination of Ethamsylate in urine and tablets.

A simple, selective, sensitive, accurate, and precise method was developed for determination of ethamsylate (ET) in human urine and in ET tablets using RP-HPLC. The method uses a C18 (5 pm particle size) column at ambient temperature with the mobile phase 14.7 mM potassium dihydrogen phosphate (pH 4.6)-8.15 mM tetraheptylammonium bromide in acetonitrile (50 + 50, v/v) at a flow rate of 1.0 mL/min. Quantitation was achieved with UV detection at 300 nm, based on peak area with a linear calibration curve in the concentration range of 0.1-100 microg/mL. The proposed method was applied for the determination of the urinary excretion pattern of ET as the cumulative amounts excreted have been calculated without pretreatment of urine samples. The proposed method was completely validated according to U.S. Food and Drug administration guidelines.

Preparation of Nile tilapia skin collagen powder by low-temperature and comprehensive evaluation of hemostasis and wound healing.

Nile tilapia (hereinafter referred to as tilapia) is a species with high economic value and extensive cultivation. In this study, the low-temperature Nile tilapia skin collagen powder (TSCP) was prepared by liquid nitrogen freeze pulverization. After physical and chemical analysis of its properties, it was found that its characteristics were similar to those of type I collagen. The three-dimensional helix structure of protein peptide is good and non denatured. It shows that cryogenic temperature guarantees the activity of TSCP. In addition, TSCP has good biocompatibility. Specifically, it has good blood compatibility, lacks cytotoxicity, will not cause intradermal stimulation and acute systemic toxicity, and has no obvious rejection after implantation. In the rat liver hemorrhage model and wound repair model, compared with the commercially available bovine collagen powder (BSCP), TSCP has better blood coagulation ability: the shortest hemostatic time (135 s) and wound healing efficiency: the wound healing is obvious on the 14th day. The results of this study indicate that the TSCP is an ideal candidate for hemostatic agents and wound healing dressings.

Acquired FXIII Deficiency is Associated with High Morbidity.

BACKGROUND: A factor XIII (FXIII) level >30% is considered necessary to prevent spontaneous bleeding. Bleeding is also a risk in patients with acquired FXIII deficiency, but the hemostatic level of FXIII in this context remains to be determined. METHODS: We retrospectively analyzed all patients diagnosed with acquired FXIII deficiency at a large hospital over 3 years (study ID NCT04416594, http://www.clinicaltrials.gov) and assessed clinical data to identify the best cut-off point for FXIII activity to distinguish between low and high risk of major bleeding in a mixed medical and surgical population. RESULTS: Of the 97 patients who experienced bleeding despite a normal coagulation test, 43.2% had FXIII activity <70%. FXIII activity was significantly lower in surgical patients and patients admitted to the intensive care unit (ICU). Low FXIII activity was significantly associated with long ICU stays and a high incidence of major bleeding. CONCLUSION: Acquired FXIII deficiency is associated with high morbidity. The hemostatic level of FXIII in the setting of acquired FXIII deficiency might be above 30%.

A comparison of fibrinogen measurement methods with fibrin clot elasticity assessed by thromboelastometry, before and after administration of fibrinogen concentrate in cardiac surgery patients.

BACKGROUND: Fibrinogen concentrate administration can be guided by measuring fibrinogen concentration or quality of the fibrin-based clot. This study compared different fibrinogen concentration measurement methods with maximum clot firmness (MCF) of the fibrin clot, assessed by thromboelastometry (FIBTEM), in 33 cardiovascular surgery patients receiving fibrinogen concentrate for hemostatic therapy. STUDY DESIGN AND METHODS: Blood samples were collected after cardiopulmonary bypass (CPB) and after fibrinogen concentrate administration. FIBTEM MCF was measured using a rotational thromboelastometry device (ROTEM, Tem International). Fibrinogen concentration was measured using photo-optical (CA-7000, Siemens Healthcare Diagnostics), mechanical (KC-10 steel ball, Schnitger and Gross hook, Amelung GmbH), and electromechanical (STA-R, Diagnostica Stago) coagulometers. Assessments included agreement between fibrinogen concentration measurements and correlations between fibrinogen concentration and FIBTEM MCF. RESULTS: After CPB, correlations were significant (p < 0.001) between FIBTEM MCF and fibrinogen concentration determined by steel ball (r = 0.71), hook (r = 0.73), STA-R (r = 0.81), and CA-7000 (r = 0.82) coagulometers. After fibrinogen concentrate administration, agreement between fibrinogen measurement methods was severely impaired, and correlations with FIBTEM MCF were 0.39 (steel ball), 0.33 (hook), 0.59 (STA-R), and 0.33 (CA-7000). CONCLUSION: Agreement between fibrinogen concentration measurement methods decreased considerably after fibrinogen concentrate administration. All methods correlated acceptably with FIBTEM MCF at the end of CPB, but not after hemostatic therapy. Further investigation is needed to explain these findings.

The effect of prion reduction in solvent/detergent-treated plasma on haemostatic variables.

BACKGROUND: Octapharma PPGmbH has recently modified its manufacturing process for solvent/detergent-treated plasma to incorporate a prion reduction step, in which a 3 log reduction has been demonstrated. The current study was undertaken to assess the impact of this procedure on haemostatic variables in the new product OctaplasLG in comparison with standard Octaplas. METHODS: Production batches of standard Octaplas (n=4) and OctaplasLG (n=16) were assessed for levels of coagulation factors, physiological protease inhibitors, markers of activation and procoagulant microparticles. Global haemostasis was assessed by a thrombin generation test (TGT) and rotational thromboelastometry (ROTEM). RESULTS: Mean levels of factors: II, V, VII, IX, X, XI, XII and XIII, VWF:Ag, antithrombin, protein C and free protein S were all >75 u/dl. ADAMTS-13 activity levels were normal. Factor VIII and VWF:RCo were >55 u/dl. TGT and ROTEM were similar in both preparations, and microparticles were present at negligible levels. Two units of OctaplasLG had slightly elevated levels of Prothrombin Fragments 1+2, but D-Dimer and thrombin-antithrombin complexes were normal in all batches. CONCLUSION: These studies indicate that the affinity chromatography procedure used in OctaplasLG does not appear to adversely affect the proven haemostatic quality of Octaplas, while offering a selective reduction in the concentration of pathological prion proteins.

Microparticles in vascular diseases.

Cellular microparticles (MP) are small membrane vesicles that are released from cells upon activation or apoptosis. They constitute a heterogeneous population of submicron elements differing in cellular origin, number, size, antigenic composition and functional properties. Circulating MP provide an additional procoagulant phospholipid surface enabling the assembly of the clotting enzyme complexes and thrombin generation. Their procoagulant properties rely on the exposure of phosphatidylserine and on the possible presence of tissue factor, the main initiator of blood coagulation. Microparticles constitute the main reservoir of blood-borne tissue factor. Derived from various cells, most notably platelets, erythrocytes, leucocytes and endothelial cells, circulating MP are detectable in the circulation of healthy subjects. Elevated levels are encountered in diseases with vascular involvement and hypercoagulability such as disseminated intravascular coagulation, diabetes, immune-mediated thrombosis, kidney diseases, acute coronary syndromes or systemic inflammatory disease, where they appear indicative of a poor clinical outcome. Converging evidence from experimental and clinical data underlines an involvement of procoagulant MP in the initiation/dissemination of procoagulant and inflammatory responses. In these clinical settings, the pharmacological modulation of MP level or activity provides challenging issues.

[Characteristics of encrustation of ureteric stents in patients with urinary stones]. / Caractéristiques des incrustations des endoprothèses urétérales chez les patients lithiasiques.

INTRODUCTION: The goal of this prospective study was to characterize ureteral stents encrustation in stone formers. MATERIAL AND METHODS: We report the results of a study based on 658 double-J stents (412 men and 246 women) collected from patients with in situ urinary calculi. The mean age was 48.2+/-16.0 years without differences between genders. Ureteral stent encrustation was analysed by infrared spectroscopy. Results are expressed according to the main component. RESULTS: The mean indwelling time was 73.5+/-73.2 days. The main component in stent encrustations was calcium oxalate (43.8%), essentially the monohydrate form (27.1%), followed by proteins (27.4%), calcium phosphates (16.4% with 8.4% brushite), and uric acid (5.2%). Struvite, detected on 49 stents, was the main component in 2.4% of cases. Significant differences according to gender and age were found: calcium oxalate monohydrate, which represented 24.5% in 20 to 29 years old men class increased to 37.0% in 50 to 59 years class and then decreased in older patients. Calcium oxalate dihydrate increased with age up to 70 years in women while it felt dramatically in man beyond 50 years old. Brushite was more abundant in young men (20.4% in patients aged 20-29 years) and was decreasing beyond this age while it remained in stable proportion for all age classes in women. Increasing prevalence of uric acid encrustations with age was observed, especially in men beyond the age of 70 years. Mineral encrustations increased with the indwelling time, the part of mineral being preponderant after 15 days: 7,3% of the stents had become massively encrusted within 113 days mean period. The comparison between biomaterials showed that silicone stents were significantly less encrusted than polyurethane stents. CONCLUSION: Stent encrustation constitutes a serious complication of ureteral stent use in stone formers. Lithogenic factors should be considered for the prevention of stent encrustation in these patients.

Hemostatic biomarkers in cancer progression.

Malignant disease is characterized by a hemostatic imbalance, usually shifted towards a procoagulant direction, and a high incidence of thrombotic complications. The mechanisms of hemostasis that are critically involved in thrombosis are also implicated in tumor progression, angiogenesis, and metastatic spread. As there is a close relationship between cancer and the clotting system, circulating biomarkers of activation of various hemostasis compartments (i.e. coagulation, fibrinolysis, platelets, endothelium, and other blood cells) have been extensively studied to predict cancer outcomes along with predicting the thrombotic risk. In this review, we will summarize the results of published studies and will focus on ongoing research and future directions of clotting activation bioproducts as biomarkers of cancer disease and progression.

Deteriorating Hemostatic Functions of Adult Female Wistar Rats Mediated by Activities of Non-Steroidal AntiInflammatory Drugs (NSAIDs) - Piroxicam and Vitamin E.

The status of hemostatic parameters, are useful physiological markers of organ and tissue damage anddysfunction. This study investigated the effect of Piroxicam on some hemostatic parameters of albino Wistar rats. Twentyfour (24) female albino Wistar rats were used for this study, they were randomly divided into four (4) groups of six (6) ratseach. Group A served as control, Group B and C were rats treated with 0.1 mg/kg and 0.2 mg/kg piroxicam while Group Dserved as 0.2 mg/kg piroxicam treated rats administered with Vitamin E. The experiment lasted for a period of 4 weeks, afterwhich the rats were euthanized. Blood sample was collected for measurement of bleeding time, clotting time, fibrinogenlevel and platelets count. One-way ANOVA was used to compare, means and a p<0.05 was considered significant. RESULT: Data generated showed that Piroxicam significantly (p<0.05) decreased the clotting time, platelets count and fibrinogen level.Piroxicam also significantly (p<0.05) increased the bleeding time level of the rats. Co-administration of Vitamin Esignificantly (p<0.05) increased the bleeding time, it also significantly decreased the clotting time, fibrinogen level andplatelets counts. CONCLUSION: This study therefore shows that Piroxicam impairs hemostasis while Vitamin E administrationfurther enhances the activities of Piroxicam on hemostatic parameters.

Determination of Menaquinone-7 by a Simplified Reversed Phase- HPLC Method.

BACKGROUND: An efficient and accurate HPLC method was developed for the determination of menaquinone-7 (MK-7) in microbial fermentation using 2-propanol and n-hexane as extraction solvents as well as the eluent. METHODS: Extraction was carried out with 2-propanol and n-hexane (2:1, v/v) after enzymatic hydrolysis with 1% (w/v) lipase and ethanol water treatment prior to quantification in order to remove interfering lipids and denatured proteins. Chromatographic separation of MK-7 was accomplished isocratically on a C 18 Gemini column using a mobile phase mixture of 2- propanol: n-hexane (2:1, v/v) with a flow rate of 0.5 mL/min. UV detection was carried out from 200-400 nm and the chromatogram was extracted at a wavelength of 248 nm. A linear response was shown by the method with a coefficient of determination (R2) value of 0.9982. RESULTS: The recoveries of MK-7 were greater than 94% and the intra and inter day R.S.D values were less than 2%, demonstrating the accuracy of the method. The lower limit of detection (LOD) and the limit of quantification (LOQ) were 0.1 µg/mL and 0.29 µg/mL, respectively. CONCLUSION: The general usefulness of the described method is demonstrated by the application of this method in the analysis of MK-7 from Bacillus species. Under these conditions, the analysis of MK-7 was achieved in less than 8 minutes with a retention time of 7.19 ± 0.1 minutes.

Prothrombin time and activated partial thromboplastin time reference intervals in dogs, by gender and age group using the Start®4 (Stago) / Intervalos de referência para o tempo de protrombina e tempo de tromboplastina parcial ativada no cão de acordo com a idade e o gênero utilizando o Start ® 4 (Stago)

Prothrombin time (PT) and the activated partial thromboplastin time (aPTT) are useful tools for the diagnosis and monitoring of coagulation disorders in Veterinary Medicine. Our objectives were: to establish reference intervals (RI) for PT and a PTT for the dog using the Start®4 (Stago), to compare the obtained RI with literature; to evaluate the effects of gender and age on the coagulation profile. Plasma samples of 122 healthy dogs (57 males; 65 females) aged between 4 months and 18 years, divided into three age groups (0-2 years old; 3-10 years old; > 10 years old) and grouped in to males and females were analysed. The RI were estimated following the ASVCP guidelines with the Reference Value Advisor software. The RI were: PT 6.7'' to 10.8''; aPTT 9.0'' to 14.8''. PT was significantly higher in females than in males. Dogs aged 10 years or older have significantly higher mean aPTT times than younger dogs. RI comparison showed a considerable percentage of cases outside the reference RI of the literature (PT - 79.3%; aPTT - 77.1%), demonstrating the need of each laboratory to calculate its own RI. The RI established in this study are applicable for the coagulation profile assessment in dogs.

O tempo de protrombina (TP) e o tempo de tromboplastina parcial ativada (TTPa) são ferramentas úteis para o diagnóstico e monitorização das alterações da coagulação em Medicina Veterinária. Os objetivos deste estudo foram: estabelecer intervalos de referência (IR) para TP e TTPa para o cão utilizando o Start®4 (Stago), de modo a comparar os IR obtidos com a literatura; avaliar os efeitos do sexo e da idade no perfil da coagulação. Foram usadas amostras de plasma de 122 cães saudáveis (57 machos; 65 fêmeas) com idades entre quatro meses e 18 anos, divididos em três grupos (0-2 anos; 3-10 anos; > 10 anos) e agrupados em machos e fêmeas. Os IR foram calculados seguindo as diretrizes da ASVCP com o software Reference Value Advisor. Os IR obtidos foram: PT 6,7 '' a 10,8 ''; TTPa 9,0 '' a 14,8 ''. O TP foi significativamente maior nas fêmeas do que nos machos. Os cães com 10 anos ou mais apresentaram tempos médios de TTPa significativamente maiores do que cães mais jovens. A comparação de IR mostrou uma percentagem considerável de casos fora do IR de referência da literatura (TP - 79,3%; TTPa - 77,1%), confirmando a necessidade de cada laboratório calcular seu próprio IR. Os IR estabelecidos neste estudo são aplicáveis na avaliação do perfil hemostático em cães.

Inactivated antithrombins as fondaparinux antidotes: a promising alternative to haemostatic agents as assessed in vitro in a thrombin-generation assay.

In the absence of specific antidote to fondaparinux, two modified forms of antithrombin (AT), one recombinant inactive (ri-AT) and the other chemically inactivated (chi-AT), were designed to antagonise AT-mediated anticoagulants, e. g. heparins or fondaparinux. These inactive ATs were previously proven to effectively neutralise anticoagulant activity associated with heparin derivatives in vitro and in vivo, as assessed by direct measurement of anti-FXa activity. This study was undertaken to evaluate in vitro the effectivity of inactive ATs to reverse anticoagulation by heparin derivatives and to compare them with non-specific fondaparinux reversal agents, like recombinant-activated factor VII (rFVIIa) or activated prothrombin-complex concentrate (aPCC), in a thrombin-generation assay (TGA). Addition of fondaparinux (3 µg/ml) to normal plasma inhibited thrombin generation by prolonging lag time (LT) as much as 244 % and lowering endogenous thrombin potential (ETP) to 17 % of their control (normal plasma) values. Fondaparinux-anticoagulant activity was reversed by ri-AT and chi-AT, as reflected by the corrections of LT up to 117 % and 114 % of its control value, and ETP recovery to 78 % and 63 %, respectively. Unlike ri-AT that had no effect on thrombin generation in normal plasma, chi-AT retained anticoagulant activity that minimises its reversal capacity. However, both ATs were more effective than rFVIIa or aPCC at neutralising fondaparinux and, unlike non-specific antidotes, inactive ATs specifically reversed AT-mediated anticoagulant activities, as suggested by their absence of procoagulant activity in anticoagulant-free plasma.

Altered fibrin clot structure in the healthy relatives of patients with premature coronary artery disease.

BACKGROUND: A family history of premature coronary artery disease (CAD) is an independent cardiovascular risk factor. Fibrin clots composed of dense fiber networks are found in young CAD patients and may occur in the relatives of such individuals. METHODS AND RESULTS: The ex vivo fibrin structure of 100 healthy male relatives of patients with premature CAD and 100 age-matched control subjects was assessed by measurement of permeability (K(s)), fiber mass-length ratio ( micro ), and turbidity (lag phase and maximum absorbency [max DeltaAbs]). Scanning electron microscopy was performed on selected samples. Relatives and controls shared similar levels of conventional cardiovascular risk factors. K(s) was lower in relatives than in controls, 12.2 (11.1 to 13.3) versus 15.2 (14.0 to 16.5) x10(-9) cm(2) (P<0.001), associated with a smaller decrease in micro, 8.5 (7.7 to 9.2) versus 9.7 (8.9 to 10.5) x 10(13) Da/cm (P<0.05), respectively. Lag phase was shorter in relatives than in controls, 39 (37 to 41) versus 47 (44 to 50) seconds (P<0.001), and max DeltaAbs was higher in relatives, 0.78 (0.74 to 0.82) versus 0.71 (0.67 to 0.74) in controls (P=0.02), which indicates the presence of thicker fibers in relatives. After adjustment for fibrinogen levels, lag phase and K(s) remained significantly different between relatives and control subjects. Scanning electron microscopy images confirmed increased fiber diameter in relatives, possibly of reduced density. Factor XIII Val34Leu and fibrinogen Aalpha Thr312Ala and Bbeta -455 G/A showed no association with clot structure. CONCLUSIONS: The male relatives of patients with premature CAD form fibrin clots that begin polymerization more quickly, have thicker fibers, and are less permeable than those of control subjects.

[Fibrinogen. An old hemostatic protein with a new function: non-invasive marker of subclinical atherosclerosis]. / Fibrinógeno. Vieja proteína hemostática con nueva función: marcador no invasivo de aterosclerosis subclínica.

The formation of a fibrin clot is one of the key events in atherothrombotic vascular diseases, such as myocardial infarction, ischemic stroke and peripheral arterial disease. Fibrin is formed from a circulating precursor, fibrinogen, by the action of thrombin. Both genetic and environmental factors are important determinants of the circulating fibrinogen levels. Epidemiologic studies have demonstrated a role for this hemostatic protein in the prediction of cardiovascular disease. As an acute-phase reactant, fibrinogen is also a marker of inflammation. Likewise, recent studies from our group have shown that increased fibrinogen levels represent a marker of subclinical atherosclerosis, likely to be useful in the identification of asymptomatic subjects at risk for cardiovascular disease.