bluuebunny/crossref_metadata_2025_split huggingface dataset:
Congenital Deficiency of Vitamin K Dependent Coagulation Factors in Two Families Presents as a Genetic Defect of the Vitamin K-Epoxide-Reductase-Complex
Authors: von Brederlow B. , Fregin A. , Rost S. , Wolz W. , Eberl W. , Eber S. , Lenz E. , Schwaab R. , Brackmann H. H. , Effenberger W. , Harbrecht U. , Schurgers L. J. , Vermeer C. , Müller C. R. , Oldenburg J. 
Published: March 2018

SummaryHereditary combined deficiency of the vitamin K dependent coagulation factors is a rare bleeding disorder. To date, only eleven families have been reported in the literature. The phenotype varies considerably with respect to bleeding tendency, response to vitamin K substitution and the presence of skeletal abnormalities, suggesting genetic heterogeneity. In only two of the reported families the cause of the disease has been elucidated as either a defect in the γ-carboxylase enzyme (1) or in a protein of the vitamin K 2,3-epoxide reductase (VKOR) complex (2).Here we present a detailed phenotypic description of two new families with an autosomal recessive deficiency of all vitamin K dependent coagulation factors. In both families offspring had experienced severe or even fatal perinatal intracerebral haemorrhage. The affected children exhibit a mild deficiency of the vitamin K dependent coagulation factors that could be completely corrected by oral substitution of vitamin K.Sequencing and haplotype analysis excluded a defect within the γ-carboxylase gene. The finding of highly increased amounts of vitamin K epoxide in all affected members of both families indicated a defect in a protein of the VKOR-multienzyme-complex. Further genetic analysis of such families will provide the basis for a more detailed understanding of the structure-function relation of the enzymes involved in vitamin K metabolism.
Capillary Microscopic and Rheological Dimensions for the Diagnosis of von Willebrand Disease in Comparison to other Haemorrhagic Diatheses
Authors: Latza Reinhard , Mürsdorf Stefan , Mrowietz Christof , Kiesewetter Holger , Wenzel Ernst , Jung Friedrich , Koscielny Jürgen 
Published: March 2018

SummaryIt is known that angiodysplasia influence macrocirculation as well as microcirculation in patients with vWD. In the present study it was examined if intravital capillary microscopic dimensions (morphologic and dynamic) in skin (nailfold) in combination with rheologic parameters could give indications for the presence of vWD in patients with haemorrhagic diathesis.Patients with vWD (n = 100; 92 type 1: definite type 1:78 and possible type 1:14; 8 type 2A) have in comparison to patients with other haemorrhagic diathesis [thrombocytopathy (n = 122), thrombocytopenia (n = 101), severe haemophilia A (n = 50) and severe haemophilia B (n = 20), congenital dysfibrinogenaemia (n = 22), oral anticoagulation with phenprocoumone (n = 112)] and to apparently healthy subjects (n = 100) a significantly increased capillary torquation (median index: 3.5), a venolar and an arteriolar capillary dilatation (median: 16.5 µm; median: 15.1 µm) and the highest part of microscopic bleedings (extravasates) with 40% in the video capillary microscopy as morphological changes. Only the congenital dysfibrinogenaemia appears with a larger dilatation in venolar capillaries (median: 14.5 µm). Microscopic bleedings are much less common in other haemorrhagic diatheses with a frequency between 4% and 13%.In the vWD a significantly reduced duration of reactive hyperaemia (median: 150 sec). This is the only dynamic change that can be taken as a possible hint for a loss of flexibility within the precapillary vessels. A significantly reduced plasma viscosity (< 1.25 mPas) is typical for the vWD due to the increase of the shear stress in blood plasma because of the reduction of vWF-activities. Changes of the capillary morphology (dilatation, extravasates, capillary torquation) and the hypoplasmaviscosity are most sensitive for the vWD (75%, 65%, 40%, 80%) with a fairly high specifity (up to 93%) and a positive predictive value of 99%.As a conclusion it seems reasonable to discuss the introduction of video capillary microscopy as a screening test for haemostasiological and angiological centers.
Characterization of Unfractionated Heparin: Comparison of Materials from the last 50 Years
Authors: Gray Elaine , Barrowcliffe Trevor , Mulloy Barbara 
Published: March 2018

SummaryPhysicochemical and anticoagulant characteristics of 27 samples from recent batches of commercially produced unfractionated heparin have been determined as part of the process of establishment of the 5th International Standard Unfractionated Heparin. They have been compared with current heparin standards (European Pharmacopoeia, United States Pharmacopoeia, Chinese), with the 4th International Standard Unfractionated Heparin, and with the three predecessor International Standards. The results indicate that the 4th International Standard Unfractionated Heparin, established in 1982, has significantly lower molecular weight and specific activity than recently produced heparin; this is also true of all preceding International Standard Heparins and of the United States Pharmacopoeial standard. The composition of commercial unfractionated heparin may therefore have changed over time; reasons for this are discussed.
An Assay to Quantify the Two Plasma Isoforms of Factor V
Authors: Hoekema Lico , Tans Guido , Rosing Jan 
Published: March 2018

SummaryBlood coagulation factor V (FV) circulates in the blood in two forms, designated FV1 and FV2. In model systems containing purified proteins FV1 appears to be more thrombogenic than FV2. Recently, we reported that in plasma from carriers of the R2 haplotype, a polymorphism which encodes several amino acid changes in FV and which is associated with an increased risk of thrombosis, the FV1/FV2 ratio is shifted in favor of the more thrombogenic form FV1. Here we describe in detail the assay that enables quantification of the plasma levels of FV1 and FV2. FV present in highly diluted plasma samples was activated with thrombin and the FVa generated was subsequently quantified in two prothrombinase-based assay systems. In the first assay, which is performed at saturating amounts of FXa and phospholipid vesicles with a high mole fraction phosphatidylserine, FVa1 and FVa2 express the same cofactor activity in prothrombin activation. Hence, this assay quantifies the total FV level (FV1 + FV2) present in plasma. In the second assay, which is performed at suboptimal amounts of FXa and phospholipid vesicles with a low mole fraction phosphatidylserine, FVa2 has approximately an 8-fold higher cofactor activity than FVa1. Therefore, the response in this assay depends on the relative amounts of FV1 and FV2 in the plasma sample. Calibration curves made with samples containing known concentrations of purified FVa1 and FVa2 subsequently allowed calculation of the amounts of FV1 and FV2 present in plasma.
Tranexamic Acid Inhibits Fibrinolysis, Shortens the Bleeding Time and Improves Platelet Function in Patients with Chronic Renal Failure
Authors: Panes Olga , Muñoz Blanca , Pais Edgar , Tagle Rodrigo , González Fernando , Mezzano Sergio , Barriga Francisco , Pereira Jaime , Mezzano Diego 
Published: March 2018

Summary
Background: A defect in platelet function is the main determinant of the prolonged bleeding time in chronic renal failure (CRF). We previously reported a significant correlation between platelet abnormalities and elevated plasma markers of plasmin and thrombin generation. Our aim was to explore the effect of inhibiting both plasmin action with tranexamic acid (TA) and thrombin production with low molecular weight heparin (LMWH), on the bleeding time (BT) and platelet function in patients with CRF. Methods: 37 patients with CRF (mean creatinine 8.6 ± 4.4 mg/dl) under conservative treatment, with prolonged BT, entered this study and received TA during 6 days, with (n = 24) and without LMWH (n = 13). BT, platelet aggregation/secretion, platelet granule contents, von Willebrand factor and parameters of coagulation and fibrinolysis were recorded before and at the end of treatment. Results: The BT was shortened in 26/37 (67%) patients. This effect was associated with significant improvement of platelet aggregation and secretion, with decrease to a normal range of fibrin/fibrinogen degradation products, mild increase in plasmin-antiplasmin complexes and pronounced reduction of circulating plasminogen. No differences were seen among patients with or without LMWH. No serious side effects or complications were observed. Interpretation: These findings indicate that the activation of fibrinolysis plays a significant role in the defect of primary hemostasis in patients with CRF. Inhibition of plasmin activity with TA shortens the BT and improves platelet function in the majority of patients with severe disease.
Anti Xa Monitoring during Treatment with Low Molecular Weight Heparin or Danaparoid: Inter-assay Variability
Authors: Iampietro R. , Woolley A. M. , Preston F. E. , Kitchen S. 
Published: March 2018

SummaryIf laboratory monitoring of low molecular weight heparin (LMWH) therapy is required the test of choice is the anti Xa activity assay. The relationship between anti Xa results obtained using different techniques is unknown. The aim of the present study was to compare anti Xa results obtained with eight different commercially available anti Xa activity assays (five chromogenic and three clotting based assays) in samples from patients receiving either therapeutic or prophylactic LMWH (enoxaparin or dalteparin) or danaparoid.We have demonstrated that highly significant differences exist between results obtained using different techniques. The mean anti Xa activity in patients receiving treatment or prophylaxis with enoxaparin ranged from 0.28 to 0.64 iu/ml. A similar relationship was present in samples from patients treated with dalteparin, mean anti Xa results ranging from 0.43 to 0.69 iu/ml. The Heptest clotting assay as used here in combination with the Automated Coagulation Laboratory instrument, was associated with lower results than other clotting or chromogenic techniques. In patients receiving danaparoid for heparin induced thrombocytopaenia (HIT) mean results with three clotting based assays were 0.30 to 0.36 u/ml, compared to mean results of 0.47 to 0.65 u/ml for chromogenic assays.Our data clearly indicate that the selection of anti Xa assay method could influence patient management since the dose required to achieve the therapeutic range would differ according to the assay employed. This is particularly important since the frequency of hamorrhagic side effects has been shown by others to be dose dependant, irrespective of the concomitant anti Xa activity results. In danaparoid therapy the clotting assays studied here should not be employed for monitoring without a modified target range, unless it can be demonstrated that the higher doses required to achieve the therapeutic range are safe.
Pretreatment with Soluble Thrombomodulin Prevents Intrasinusoidal Coagulation and Liver Dysfunction following Extensive Hepatectomy in Cirrhotic Rats
Authors: Kaido Toshimi , Yoshikawa Akira , Seto Shin-ichi , Yamaoka Shoji , Furuyama Hiroaki , Arii Shigeki , Imamura Masayuki , Takahashi Yasuo 
Published: March 2018

SummaryThe major cause of posthepatectomy liver dysfunction is supposed to be microcirculatory disturbance caused by imbalance of intrasinusoidal coagulation equilibrium. Thrombomodulin (TM) is a potent anticoagulant expressed on the endothelial cell surface that regulates the coagulation system by binding thrombin and accelerating the thrombin-catalyzed activation of protein C. Therefore, we examined the effect of soluble TM purified from human urine (UTM) on intrasinusoidal coagulation in cirrhotic rats. Dimethylnitrosamine-induced cirrhotic rats underwent 70% hepatectomy and received endotoxin 48 h after. UTM or vehicle alone was intravenously administered to each rat 30 min before endotoxin injection. UTM treatment attenuated the increases in cytosolic enzymes and serum hyaluronic acid level. The UTM supply improved the survival rate of the rats at 12 h after endotoxin challenge. Histologically, intrasinusoidal fibrin depositions and massive hepatocellular necrosis observed in control rats were scarcely found in UTM-treated rats. Immunohistochemical examination revealed that marked TM stains in sinusoidal endothelial cells were well preserved in UTM-treated rats. In conclusion, UTM administration prevented intrasinusoidal fibrin depositions and attenuated posthepatectomy liver dysfunction in cirrhotic rats.
Cloning and Expression of Canine Glycoprotein Ibα
Authors: Morateck Patricia , Fahs Scot , Warltier David , Montgomery Robert , Kenny Dermot 
Published: March 2018

SummaryThe interaction of the glycoprotein (GP) Ib-IX-V complex with von Willebrand factor (vWF) is critical in initiation of haemostasis and thrombosis through platelet adhesion to damaged endothelium. The binding site for vWF resides within the GPIbα subunit of the complex. To further define the physiological function of platelet GPIbα we cloned and expressed the canine GPIbα cDNA. A canine platelet cDNA library was constructed and screened with a randomly primed 32P-labeled 1041-base-pair restriction fragment of the human GPIbα cDNA. Analysis of 23 clones demonstrated that the canine GPIbα cDNA is 2530 nucleotides in length and includes a short 5’ untranslated segment of 42 nucleotides followed by a signal peptide of 16 amino acids, a mature peptide of 645 amino acids and a 3’ noncoding region of 455 nucleotides. A single intron of 142 nucleotides, 6 nucleotides upstream from the ATG translation initiation codon was identified in the canine gene in a similar location to that present in the human gene.Chinese hamster ovary cells that stably express human GPIbα and GPIX were transfected with the canine GPIbα cDNA. Canine GPIbα was expressed on the surface of these cells and bound vWF in the presence of botrocetin. The binding of vWF was inhibited by an anti-vWF human monoclonal antibody known to inhibit vWF binding to GPIbα. The results of this investigation will allow the development of reagents to study the physiological function of GPIbα in an animal model.
Thrombomodulin: A New Marker for Placental Abruption
Authors: Chan Daniel , Bruzek Debra , Copel Joshua , Hsu Chaur-Dong , Magriples Urania 
Published: March 2018

SummaryThrombomodulin (TM), a marker of endothelial cell damage, has been localized to the placental syncytiotrophoblast. A prospective cohort study of twenty-five pregnant women who were admitted with a clinical diagnosis of placental abruption was undertaken. Abruption was confirmed after delivery in eight cases (Group 1). Group 2 consisted of seventeen patients with no clinical or pathologic evidence of placental abruption after delivery. TM was significantly elevated in Group 1 (71.59 ± 5.35 vs. 48.29 ± 3.53 ng/ml, p = 0.001). The sensitivity and specificity of TM ≥60 ng/ml as a marker for abruption was 87.5 and 76.5%, respectively. In comparison, the sensitivity of an abnormal coagulation profile, maternal Kleihauer-Betke and ultrasound in patients with abruption was 0, 16.7 and 28.6%, respectively. TM is a highly sensitive and specific marker for acute placental abruption.
Monocyte Plasminogen Activator Inhibitor 2 (PAI-2) Inhibits u-PA-mediated Fibrin Clot Lysis and Is Cross-linked to Fibrin
Authors: Robbie Linda , Kinghorn Seonag , Exley Rachel , Booth Nuala , Ritchie Helen 
Published: March 2018

SummaryPlasminogen activator inhibitor 2 (PAI-2) is a major product of activated human monocytes. Here we show that monocytes inhibited u-PA- but not t-PA-mediated fibrinolysis, by secreting PAI-2 into an overlying fibrin clot. Extracts of arterial and venous human thrombi were found to contain active PAI-2. PAI-2 was cross-linked to fibrin in a reaction catalyzed by two major transglutaminases (TG), tissue TG and factor XIII. The activity of PAI-2 was not affected by such cross-linking. Cross-linking of PAI-2 to fibrin was inhibited by Tridegin, a specific inhibitor of TG, and also by EDTA and iodoacetamide. The use of competitive peptides mimicking the loop between helices C and D of PAI-2 identified Gln 83 and 86 as residues important in cross-linking. This study defines a mechanism by which PAI-2 is localized to fibrin, where it acts as an effective inhibitor of u-PA-mediated fibrinolysis.
Epinephrine Promotes IL-8 Production in Human Leukocytes via an Effect on Platelets
Authors: Østerud Bjarne , Engstad Charlotte , Lund Trine 
Published: March 2018

SummaryInterleukin-8 (IL-8) is generally accepted to be an important mediator of a number of acute and chronic inflammatory diseases and is produced by monocytes upon stimulation by lipopolysaccharide (LPS). Epinephrine has been reported by several groups to suppress activation of monocytes in response to LPS, and the aim of the present study was to examine the effect of epinephrine on LPS induced IL-8 production using whole blood as a model system. Epinephrine increased LPS induced IL-8 production in a dose-dependent manner in the whole concentration range (0.001–100 μM) and 1 μM epinephrine increased IL-8 levels with 125%. Epinephrine per se had no effect on IL-8 levels. The potentiating effect of epinephrine was mediated by blood platelets, since IL-8 levels in samples containing platelets and stimulated with LPS and epinephrine (1–100 μM) were significantly higher (p <0.05) than in control samples containing no platelets. This effect of platelets seemed to be due to platelet release products, since addition of 25 μl platelet lysate supernatant to whole blood increased LPS induced IL-8 production with 100% and a similar effect was observed in freshly isolated mononuclear cells resuspended in plasma. Upon addition of 50 μg/ml of the carboxyterminal peptide of platelet factor 4 (PF4(58-70)) to whole blood, LPS stimulated IL-8 levels were increased with 115%, whereas in mononuclear cells, 20 μg/ml PF4(58-70) enhanced IL-8 production with 40%. We demonstrate for the first time that epinephrine promotes LPS induced production of IL-8 in whole blood via an effect on blood platelets. This potentiating effect of platelets is shown to be due to platelet granule contents, and platelet factor 4 (PF4) is suggested to be one of several platelet granule proteins promoting LPS induced IL-8 production in whole blood.
Multicenter Evaluation of Lyophilized and Deep-frozen Plasmas for Assignment of the International Normalized Ratio
Authors: Houbouyan-Reveillard L. L. , Aillaud M. F. , Denson K. W. E. , Droullé C. , Johnston M. , Kitchen S. , Lindahl T. L. , Marren M. , Martinuzzo M. E. , Tripodi A. , Vergnes C. , van den Besselaar A. M. H. P. 
Published: March 2018

SummaryThe interlaboratory variation of the International Normalized Ratio (INR) in various external quality assessment schemes is still relatively high. This is partly caused by inaccuracy of manufacturers’ stated International Sensitivity Index (ISI) and/or local instrumentation effects. The interlaboratory variation and accuracy of INR determinations may be improved by a local calibration procedure based on lyophilized plasmas with assigned INRs. The purpose of the present study was to determine INR values for different types of lyophilized plasmas to be used for local calibration. A total of 13 lyophilized plasmas (one normal, six from coumarin-treated patients, six artificially depleted) were analyzed by 10 laboratories, each using five calibrated prothrombin time (PT) systems. INRs were calculated for each plasma using each laboratory’s specific ISI and mean normal prothrombin time values. In the same way, five deep-frozen pooled plasmas from coumarin-treated patients were analyzed. There were significant INR differences for the lyophilized plasmas between the prothrombin time systems. The differences were relatively small for the deep-frozen coumarin plasmas (CV 2.6-3.3%) and three lyophilized coumarin plasmas from one manufacturer (CV 3.7-4.8%). Important INR differences were observed for three lyophilized coumarin plasmas from another manufacturer (CV 9.5-14.1%) and several artificially depleted plasmas (CV 5.3-12.8%). The citrate concentrations in the artificially depleted plasmas were lower than those in the normal and coumarin plasmas. These differences should be considered in the selection and certification of plasmas as calibrants for local calibration of PT systems. The lyophilized plasmas’ INR values obtained in the present study will be used for a field study of local PT calibration to assess their efficacy.
A New Factor Xa Inhibitor (Lefaxin) from the Haementeria depressa Leech
Authors: Faria Fernanda , Kelen Eva Maria , Sampaio Claudio , Bon Cassian , Duval Nathalie , Chudzinski-Tavassi Ana Marisa 
Published: March 2018

SummaryThe salivary complex of the leech Haementeria depressa produces potent anticoagulant components. Among them, a protein named lefaxin inhibits factor Xa (FXa). Lefaxin was purified to homogeneity from dissected salivary complexes by gel filtration in Sephadex G-150 followed by two ion exchange chromatography steps in Mono-Q. Inhibition of FXa by lefaxin was demonstrated by the inhibition of its amidolytic activity, measured with chromogenic substrate S-2765 (apparent KI of 4 nM), and of its ability to inhibit thrombin generation in the prothrombinase complex (EC50 of 40 nM). Lefaxin has a molecular weight of 30 kDa and an isoelectric point of 5.7. It is made of a polypeptide chain whose N-terminal sequence shows no similarity with that of other FXa inhibitors (antistasin and ghilianten) isolated from leech saliva. On the other hand, the N-terminal sequence of lefaxin presents significant sequence similarity with nitric oxide carrier proteins myohemerythrin from the annelid Nereis diversicolor and prolixin S from the tick Rhodnius prolixus. Interestingly, prolixin S also proved to be an anticoagulant protein acting on FXa.
Relationship between Visceral Fat and PAI-1 in Overweight Men and Women before and after Weight Loss
Authors: Kockx M. , Leenen R. , Seidell J. , Princen H. M. G. , Kooistra T. 
Published: March 2018

SummaryThis study was aimed at evaluating the relationship between visceral fat accumulation and plasma plasminogen activator inhibitor-1 (PAI-1) levels in healthy, obese men and women undergoing weight loss therapy. The subjects, 25 men and 25 premenopausal women, aged between 26 and 49 years, with an initial body mass index between 28 and 38 kg/m2, received a controlled diet for 13 weeks providing a 4.2 MJ/day energy deficit. Magnetic resonance imaging was used to measure visceral and subcutaneous abdominal fat. Our results show that before weight loss visceral fat was significantly correlated with PAI-1 in men (r = 0.45; p <0.05), but not in women (r = -0.15; ns). The association between visceral fat and PAI-1 in men remained significant after adjustment for age and total fat mass, and multiple linear regression analysis showed a significant independent contribution of visceral fat to plasma PAI-1 levels. Both visceral fat areas and PAI-1 levels decreased significantly with weight loss in both men and women. Changes in visceral fat area were related to changes in PAI-1 in women (r = -0.43; p = 0.05) but not in men (r = -0.01; ns); however, this association in women disappeared after adjustment for total fat mass. We conclude that there is a relationship between visceral fat and PAI-1 in obese men but not in obese women, and that PAI-1 levels decrease substantially (52%) by weight loss, but this change is not related to changes in visceral fat mass per se.